WorldWideScience

Sample records for larger molecular size

  1. The mean-size dependence of the exchange narrowing in molecular J-aggregates

    International Nuclear Information System (INIS)

    Chen Yulu; Zhao Jijun

    2011-01-01

    The effect of segment-size fluctuations on exchange narrowing in a molecular J-aggregate of site-energy disordered distributions is studied using a one-dimensional Frenkel-exciton model. It is found that the segment-size disorder leads to the width of the absorption spectra deviating from the scaling law, σ 4/3 of the site-energy disordered standard deviation σ, being suitable for the system only with the site-energy disorder. In larger σ, the segment-size disorder has little influence on the linear absorption spectra. With increasing segment mean-length, the absorption line width monotonically increases, and then approaches a saturated value. By comparing a system of larger mean-length segment with a smaller one, both with the same segment-size disorder, it is found that the absorption line width of the former is broadened, and the exchange narrowing effect is reduced. The present result shows that the correlation effect can be partially maintained for the system with larger mean-length segment. -- Research Highlights: → Segment fluctuations affect the exchange narrowing of molecular J-aggregates. → The width of the absorption spectra is found to deviate from the scaling law. → Increase in segment size causes increase in the width and then saturates. → Exchange narrowing is reduced for larger mean-size segment. → Correlation can be kept partly in the larger size segment.

  2. Effects of anion size and concentration on electrolyte invasion into molecular-sized nanopores

    International Nuclear Information System (INIS)

    Liu Ling; Chen Xi; Kim, Taewan; Han Aijie; Qiao Yu

    2010-01-01

    When an electrolyte solution is pressurized into a molecular-sized nanopore, oppositely charged ions are strongly inclined to aggregate, which effectively reduces the ion solubility to zero. Inside the restrictive confinement, a unique quasi-periodic structure is formed where the paired ion couples are periodically separated by a number of water molecules. As the anion size or ion concentration varies, the geometrical characteristics of the confined ion structure would change considerably, leading to a significant variation in the transport pressure. Both experimental and simulation results indicate that, contradictory to the prediction of conventional theory, infiltration pressure decreases as the anions become larger.

  3. Juvenile exposure to predator cues induces a larger egg size in fish

    Science.gov (United States)

    Segers, Francisca H. I. D.; Taborsky, Barbara

    2012-01-01

    When females anticipate a hazardous environment for their offspring, they can increase offspring survival by producing larger young. Early environmental experience determines egg size in different animal taxa. We predicted that a higher perceived predation risk by juveniles would cause an increase in the sizes of eggs that they produce as adults. To test this, we exposed juveniles of the mouthbrooding cichlid Eretmodus cyanostictus in a split-brood experiment either to cues of a natural predator or to a control situation. After maturation, females that had been confronted with predators produced heavier eggs, whereas clutch size itself was not affected by the treatment. This effect cannot be explained by a differential female body size because the predator treatment did not influence growth trajectories. The observed increase of egg mass is likely to be adaptive, as heavier eggs gave rise to larger young and in fish, juvenile predation risk drops sharply with increasing body size. This study provides the first evidence that predator cues perceived by females early in life positively affect egg mass, suggesting that these cues allow her to predict the predation risk for her offspring. PMID:21976689

  4. Size selectivity of commercial (300 MC) and larger square mesh top ...

    African Journals Online (AJOL)

    In the present study, size selectivity of a commercial (300 MC) and a larger square mesh top panel (LSMTPC) codend for blue whiting (Micromesistius poutassou) were tested on a commercial trawl net in the international waters between Turkey and Greece. Trawling, performed during daylight was carried out at depths ...

  5. Larger ATV engine size correlates with an increased rate of traumatic brain injury.

    Science.gov (United States)

    Butts, C Caleb; Rostas, Jack W; Lee, Y L; Gonzalez, Richard P; Brevard, Sidney B; Frotan, M Amin; Ahmed, Naveed; Simmons, Jon D

    2015-04-01

    Since the introduction of all-terrain vehicles (ATV) to the United States in 1971, injuries and mortalities related to their use have increased significantly. Furthermore, these vehicles have become larger and more powerful. As there are no helmet requirements or limitations on engine-size in the State of Alabama, we hypothesised that larger engine size would correlate with an increased incidence of traumatic brain injury (TBI) in patients following an ATV crash. Patient and ATV data were prospectively collected on all ATV crashes presenting to a level one trauma centre from September 2010 to May 2013. Collected data included: demographics, age of driver, ATV engine size, presence of helmet, injuries, and outcomes. The data were grouped according to the ATV engine size in cubic centimetres (cc). For the purposes of this study, TBI was defined as any type of intracranial haemorrhage on the initial computed tomography scan. There were 61 patients identified during the study period. Two patients (3%) were wearing a helmet at the time of injury. Patients on an ATV with an engine size of 350 cc or greater had higher Injury Severity Scores (13.9 vs. 7.5, p ≤ 0.05) and an increased incidence of TBI (26% vs. 0%, p ≤ 0.05) when compared to patients on ATV's with an engine size less than 350 cc. Patients on an ATV with an engine size of 350 cc or greater were more likely to have a TBI. The use of a helmet was rarely present in this cohort. Legislative efforts to implement rider protection laws for ATVs are warranted. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. Molecular size distribution of Np(V)-humate

    International Nuclear Information System (INIS)

    Sakamoto, Yoshiaki; Nagao, Seiya; Tanaka, Tadao

    1996-10-01

    Molecular size distributions of humic acid and Np(V)-humate were studied as a function of pH and an ionic strength by an ultrafiltration method. Small particle (10,000-30,000 daltons) of humic acid increased slightly with increases in solution pH. The ion strength dependence of the molecular size distribution was clearly observed for humic acid. The abundance ratio of humic acid in the range from 10,000 to 30,000 daltons increased with the ionic strength from 0.015 M to 0.105 M, in place of the decreasing of that in range from 30,000 to 100,000 daltons. Most of neptunium(V) in the 200 mg/l of the humic acid solution was fractionated into 10,000-30,000 daltons. The abundance ratio of neptunium(V) in the 10,000-30,000 daltons was not clearly dependent on pH and the ionic strength of the solution, in spite of the changing in the molecular size distribution of humic acid by the ionic strength. These results imply that the molecular size distribution of Np(V)-humate does not simply obey by that of the humic acid. Stability constant of Np(V)-humate was measured as a function of the molecular size of the humic acid. The stability constant of Np(V)-humate in the range from 10,000 to 30,000 daltons was highest value comparing with the constants in the molecular size ranges of 100,000 daltons-0.45μm, 30,000-100,000, 5,000-10,000 daltons and under 5,000 daltons. These results may indicate that the Np(V) complexation with humic acid is dominated by the interaction of neptunyl ion with the humic acid in the specific molecular size range. (author)

  7. Molecular diversity patterns among various phytoplankton size-fractions in West Greenland in late summer

    Science.gov (United States)

    Elferink, Stephanie; Neuhaus, Stefan; Wohlrab, Sylke; Toebe, Kerstin; Voß, Daniela; Gottschling, Marc; Lundholm, Nina; Krock, Bernd; Koch, Boris P.; Zielinski, Oliver; Cembella, Allan; John, Uwe

    2017-03-01

    Arctic regions have experienced pronounced biological and biophysical transformations as a result of global change processes over the last several decades. Current hypotheses propose an elevated impact of those environmental changes on the biodiversity, community composition and metabolic processes of species. The effects on ecosystem function and services, particularly when invasive or toxigenic harmful species become dominant, can be expressed over a wide range of temporal and spatial scales in plankton communities. Our study focused on the comparison of molecular biodiversity of three size-fractions (micro-, nano-, picoplankton) in the coastal pelagic zone of West Greenland and their association with environmental parameters. Molecular diversity was assessed via parallel amplicon sequencing the 28S rRNA hypervariable D1/D2 region. We showed that biodiversity distribution within the area of Uummannaq Fjord, Vaigat Strait and Disko Bay differed markedly within and among size-fractions. In general, we observed a higher diversity within the picoplankton size fraction compared to the nano- and microplankton. In multidimensional scaling analysis, community composition of all three size fractions correlated with cell size, silicate and phosphate, chlorophyll a (chl a) and dinophysistoxin (DTX). Individually, each size fraction community composition also correlated with other different environmental parameters, i.e. temperature and nitrate. We observed a more homogeneous community of the picoplankton across all stations compared to the larger size classes, despite different prevailing environmental conditions of the sampling areas. This suggests that habitat niche occupation for larger-celled species may lead to higher functional trait plasticity expressed as an enhanced range of phenotypes, whereas smaller organisms may compensate for lower potential plasticity with higher diversity. The presence of recently identified toxigenic harmful algal bloom (HAB) species (such

  8. When larger brains do not have more neurons: Increased numbers of cells are compensated by decreased average cell size across mouse individuals

    Directory of Open Access Journals (Sweden)

    Suzana eHerculano-Houzel

    2015-06-01

    Full Text Available There is a strong trend toward increased brain size in mammalian evolution, with larger brains composed of more and larger neurons than smaller brains across species within each mammalian order. Does the evolution of increased numbers of brain neurons, and thus larger brain size, occur simply through the selection of individuals with more and larger neurons, and thus larger brains, within a population? That is, do individuals with larger brains also have more, and larger, neurons than individuals with smaller brains, such that allometric relationships across species are simply an extension of intraspecific scaling? Here we show that this is not the case across adult male mice of a similar age. Rather, increased numbers of neurons across individuals are accompanied by increased numbers of other cells and smaller average cell size of both types, in a trade-off that explains how increased brain mass does not necessarily ensue. Fundamental regulatory mechanisms thus must exist that tie numbers of neurons to numbers of other cells and to average cell size within individual brains. Finally, our results indicate that changes in brain size in evolution are not an extension of individual variation in numbers of neurons, but rather occur through step changes that must simultaneously increase numbers of neurons and cause cell size to increase, rather than decrease.

  9. Ventricular arrhythmia burst is an independent indicator of larger infarct size even in optimal reperfusion in STEMI

    NARCIS (Netherlands)

    van der Weg, Kirian; Majidi, Mohamed; Haeck, Joost D. E.; Tijssen, Jan G. P.; Green, Cynthia L.; Koch, Karel T.; Kuijt, Wichert J.; Krucoff, Mitchell W.; Gorgels, Anton P. M.; de Winter, Robbert J.

    2016-01-01

    We hypothesized that ventricular arrhythmia (VA) bursts during reperfusion phase are a marker of larger infarct size despite optimal epicardial and microvascular perfusion. 126 STEMI patients were studied with 24h continuous, 12-lead Holter monitoring. Myocardial blush grade (MBG) was determined and

  10. Weapons make the man (larger: formidability is represented as size and strength in humans.

    Directory of Open Access Journals (Sweden)

    Daniel M T Fessler

    Full Text Available In order to determine how to act in situations of potential agonistic conflict, individuals must assess multiple features of a prospective foe that contribute to the foe's resource-holding potential, or formidability. Across diverse species, physical size and strength are key determinants of formidability, and the same is often true for humans. However, in many species, formidability is also influenced by other factors, such as sex, coalitional size, and, in humans, access to weaponry. Decision-making involving assessments of multiple features is enhanced by the use of a single summary variable that encapsulates the contributions of these features. Given both a the phylogenetic antiquity of the importance of size and strength as determinants of formidability, and b redundant experiences during development that underscore the contributions of size and strength to formidability, we hypothesize that size and strength constitute the conceptual dimensions of a representation used to summarize multiple diverse determinants of a prospective foe's formidability. Here, we test this hypothesis in humans by examining the effects of a potential foe's access to weaponry on estimations of that individual's size and strength. We demonstrate that knowing that an individual possesses a gun or a large kitchen knife leads observers to conceptualize him as taller, and generally larger and more muscular, than individuals who possess only tools or similarly mundane objects. We also document that such patterns are not explicable in terms of any actual correlation between gun ownership and physical size, nor can they be explained in terms of cultural schemas or other background knowledge linking particular objects to individuals of particular size and strength. These findings pave the way for a fuller understanding of the evolution of the cognitive systems whereby humans--and likely many other social vertebrates--navigate social hierarchies.

  11. TaGS5-3A, a grain size gene selected during wheat improvement for larger kernel and yield.

    Science.gov (United States)

    Ma, Lin; Li, Tian; Hao, Chenyang; Wang, Yuquan; Chen, Xinhong; Zhang, Xueyong

    2016-05-01

    Grain size is a dominant component of grain weight in cereals. Earlier studies have shown that OsGS5 plays a major role in regulating both grain size and weight in rice via promotion of cell division. In this study, we isolated TaGS5 homoeologues in wheat and mapped them on chromosomes 3A, 3B and 3D. Temporal and spatial expression analysis showed that TaGS5 homoeologues were preferentially expressed in young spikes and developing grains. Two alleles of TaGS5-3A, TaGS5-3A-T and TaGS5-3A-G were identified in wheat accessions, and a functional marker was developed to discriminate them. Association analysis revealed that TaGS5-3A-T was significantly correlated with larger grain size and higher thousand kernel weight. Biochemical assays showed that TaGS5-3A-T possesses a higher enzymatic activity than TaGS5-3A-G. Transgenic rice lines overexpressing TaGS5-3A-T also exhibited larger grain size and higher thousand kernel weight than TaGS5-3A-G lines, and the transcript levels of cell cycle-related genes in TaGS5-3A-T lines were higher than those in TaGS5-3A-G lines. Furthermore, systematic evolution analysis in diploid, tetraploid and hexaploid wheat showed that TaGS5-3A underwent strong artificial selection during wheat polyploidization events and the frequency changes of two alleles demonstrated that TaGS5-3A-T was favoured in global modern wheat cultivars. These results suggest that TaGS5-3A is a positive regulator of grain size and its favoured allele TaGS5-3A-T exhibits a larger potential application in wheat high-yield breeding. © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  12. MASSIVE GALAXIES ARE LARGER IN DENSE ENVIRONMENTS: ENVIRONMENTAL DEPENDENCE OF MASS–SIZE RELATION OF EARLY-TYPE GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Yongmin; Im, Myungshin; Kim, Jae-Woo, E-mail: yymx2@astro.snu.ac.kr, E-mail: mim@astro.snu.ac.kr [Center for the Exploration of the Origin of the Universe (CEOU), Astronomy Program, Department of Physics and Astronomy, Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul, 151-742 (Korea, Republic of)

    2017-01-01

    Under the Λ cold dark matter (ΛCDM) cosmological models, massive galaxies are expected to be larger in denser environments through frequent hierarchical mergers with other galaxies. Yet, observational studies of low-redshift early-type galaxies have shown no such trend, standing as a puzzle to solve during the past decade. We analyzed 73,116 early-type galaxies at 0.1 ≤  z  < 0.15, adopting a robust nonparametric size measurement technique and extending the analysis to many massive galaxies. We find for the first time that local early-type galaxies heavier than 10{sup 11.2} M {sub ⊙} show a clear environmental dependence in mass–size relation, in such a way that galaxies are as much as 20%–40% larger in the densest environments than in underdense environments. Splitting the sample into the brightest cluster galaxies (BCGs) and non-BCGs does not affect the result. This result agrees with the ΛCDM cosmological simulations and suggests that mergers played a significant role in the growth of massive galaxies in dense environments as expected in theory.

  13. Evaluation of Kirkwood-Buff integrals via finite size scaling: a large scale molecular dynamics study

    Science.gov (United States)

    Dednam, W.; Botha, A. E.

    2015-01-01

    Solvation of bio-molecules in water is severely affected by the presence of co-solvent within the hydration shell of the solute structure. Furthermore, since solute molecules can range from small molecules, such as methane, to very large protein structures, it is imperative to understand the detailed structure-function relationship on the microscopic level. For example, it is useful know the conformational transitions that occur in protein structures. Although such an understanding can be obtained through large-scale molecular dynamic simulations, it is often the case that such simulations would require excessively large simulation times. In this context, Kirkwood-Buff theory, which connects the microscopic pair-wise molecular distributions to global thermodynamic properties, together with the recently developed technique, called finite size scaling, may provide a better method to reduce system sizes, and hence also the computational times. In this paper, we present molecular dynamics trial simulations of biologically relevant low-concentration solvents, solvated by aqueous co-solvent solutions. In particular we compare two different methods of calculating the relevant Kirkwood-Buff integrals. The first (traditional) method computes running integrals over the radial distribution functions, which must be obtained from large system-size NVT or NpT simulations. The second, newer method, employs finite size scaling to obtain the Kirkwood-Buff integrals directly by counting the particle number fluctuations in small, open sub-volumes embedded within a larger reservoir that can be well approximated by a much smaller simulation cell. In agreement with previous studies, which made a similar comparison for aqueous co-solvent solutions, without the additional solvent, we conclude that the finite size scaling method is also applicable to the present case, since it can produce computationally more efficient results which are equivalent to the more costly radial distribution

  14. Evaluation of Kirkwood-Buff integrals via finite size scaling: a large scale molecular dynamics study

    International Nuclear Information System (INIS)

    Dednam, W; Botha, A E

    2015-01-01

    Solvation of bio-molecules in water is severely affected by the presence of co-solvent within the hydration shell of the solute structure. Furthermore, since solute molecules can range from small molecules, such as methane, to very large protein structures, it is imperative to understand the detailed structure-function relationship on the microscopic level. For example, it is useful know the conformational transitions that occur in protein structures. Although such an understanding can be obtained through large-scale molecular dynamic simulations, it is often the case that such simulations would require excessively large simulation times. In this context, Kirkwood-Buff theory, which connects the microscopic pair-wise molecular distributions to global thermodynamic properties, together with the recently developed technique, called finite size scaling, may provide a better method to reduce system sizes, and hence also the computational times. In this paper, we present molecular dynamics trial simulations of biologically relevant low-concentration solvents, solvated by aqueous co-solvent solutions. In particular we compare two different methods of calculating the relevant Kirkwood-Buff integrals. The first (traditional) method computes running integrals over the radial distribution functions, which must be obtained from large system-size NVT or NpT simulations. The second, newer method, employs finite size scaling to obtain the Kirkwood-Buff integrals directly by counting the particle number fluctuations in small, open sub-volumes embedded within a larger reservoir that can be well approximated by a much smaller simulation cell. In agreement with previous studies, which made a similar comparison for aqueous co-solvent solutions, without the additional solvent, we conclude that the finite size scaling method is also applicable to the present case, since it can produce computationally more efficient results which are equivalent to the more costly radial distribution

  15. Obturator externus was larger, while obturator internus size was similar in ballet dancers compared to nondancing athletes.

    Science.gov (United States)

    Mayes, Susan; Ferris, April-Rose; Smith, Peter; Cook, Jill

    2018-06-02

    To compare the cross-sectional area (CSA) of hip external rotators, obturator externus (OE) and obturator internus (OI), in ballet dancers and nondancing athletes, and evaluate the relationship between obturator muscle size and hip pain. Case-control study. Elite ballet and sport. 33 male and female professional ballet dancers and 33 age and sex-matched athletes. CSA's of OE and OI measured on magnetic resonance imaging (MRI) of one hip. Hip pain was scored with the Copenhagen Hip and Groin Outcome Score (HAGOS): HAGOS pain score of 100 was defined as no pain and a score less than 100 was defined as pain. Participants weight and height. Estimated marginal mean CSA of OE was 14% larger in dancers than athletes (p = 0.01, ηp2 = 0.1); the size of OI was similar (p > 0.05). Men and women in both groups had similar sized OI and OE. There was no interaction between the estimated marginal mean CSA of either obturator and hip pain. It appears that ballet selectively increases muscle size of OE, but not OI. Obturator size was not related to mild hip pain, as OE and OI size was similar in dancers and athletes with and without pain. Copyright © 2018. Published by Elsevier Ltd.

  16. Influence of the apparent molecular size of humic substances on the efficiency of coagulation using Fenton's reagent

    Directory of Open Access Journals (Sweden)

    MARCELO DE JULIO

    2013-06-01

    Full Text Available This work used Fenton's reagent as a coagulating agent in the treatment of water samples with high true colour caused by humic substances (HS extracted from peat. In addition, the effects of the apparent molecular size of HS on coagulation, flocculation and flotation were studied. To that end, four distinct water samples having the same true colour were prepared using HS with different molecular sizes, which were obtained by ultrafiltration fractioning. Through optimisation of coagulant dosage and coagulation pH, as well as posterior construction of coagulation diagrams for each water sample, it was verified that the sample prepared with the smallest apparent molecular size of HS was the most difficult to treat, requiring higher coagulant (Fenton's reagent dosages than samples prepared with larger HS molecular sizes. Furthermore, filtration experiments after dissolved air flotation (DAF were carried out in an attempt to simulate conventional treatment. The most representative results in filtered water were: apparent colour ≤ 3 HU; turbidity Este trabalho empregou o reagente de Fenton como agente coagulante no tratamento de águas contendo cor elevada causada pela introdução de substâncias húmicas extraídas de turfa. Além disto, foi estudado o efeito do tamanho molecular aparente das substâncias húmicas na eficiência da coagulação, floculação e flotação de águas; para isto foram preparadas quatro águas distintas apresentado a mesma cor verdadeira, mas com substâncias húmicas de diferentes tamanhos moleculares, obtidas por fracionamento por ultrafiltração. Por meio da otimização da dosagem de coagulante e respectivo pH de coagulação e posterior construção dos diagramas de coagulação para cada água de estudo, verificou-se que a água preparada com as substâncias húmicas de menor tamanho molecular aparente apresentou maior grau de dificuldade para tratamento, requerendo dosagens de coagulante (reagente de Fenton bem

  17. Artificial selection on relative brain size in the guppy reveals costs and benefits of evolving a larger brain.

    Science.gov (United States)

    Kotrschal, Alexander; Rogell, Björn; Bundsen, Andreas; Svensson, Beatrice; Zajitschek, Susanne; Brännström, Ioana; Immler, Simone; Maklakov, Alexei A; Kolm, Niclas

    2013-01-21

    The large variation in brain size that exists in the animal kingdom has been suggested to have evolved through the balance between selective advantages of greater cognitive ability and the prohibitively high energy demands of a larger brain (the "expensive-tissue hypothesis"). Despite over a century of research on the evolution of brain size, empirical support for the trade-off between cognitive ability and energetic costs is based exclusively on correlative evidence, and the theory remains controversial. Here we provide experimental evidence for costs and benefits of increased brain size. We used artificial selection for large and small brain size relative to body size in a live-bearing fish, the guppy (Poecilia reticulata), and found that relative brain size evolved rapidly in response to divergent selection in both sexes. Large-brained females outperformed small-brained females in a numerical learning assay designed to test cognitive ability. Moreover, large-brained lines, especially males, developed smaller guts, as predicted by the expensive-tissue hypothesis, and produced fewer offspring. We propose that the evolution of brain size is mediated by a functional trade-off between increased cognitive ability and reproductive performance and discuss the implications of these findings for vertebrate brain evolution. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Biomimetic supercontainers for size-selective electrochemical sensing of molecular ions

    Science.gov (United States)

    Netzer, Nathan L.; Must, Indrek; Qiao, Yupu; Zhang, Shi-Li; Wang, Zhenqiang; Zhang, Zhen

    2017-04-01

    New ionophores are essential for advancing the art of selective ion sensing. Metal-organic supercontainers (MOSCs), a new family of biomimetic coordination capsules designed using sulfonylcalix[4]arenes as container precursors, are known for their tunable molecular recognition capabilities towards an array of guests. Herein, we demonstrate the use of MOSCs as a new class of size-selective ionophores dedicated to electrochemical sensing of molecular ions. Specifically, a MOSC molecule with its cavities matching the size of methylene blue (MB+), a versatile organic molecule used for bio-recognition, was incorporated into a polymeric mixed-matrix membrane and used as an ion-selective electrode. This MOSC-incorporated electrode showed a near-Nernstian potentiometric response to MB+ in the nano- to micro-molar range. The exceptional size-selectivity was also evident through contrast studies. To demonstrate the practical utility of our approach, a simulated wastewater experiment was conducted using water from the Fyris River (Sweden). It not only showed a near-Nernstian response to MB+ but also revealed a possible method for potentiometric titration of the redox indicator. Our study thus represents a new paradigm for the rational design of ionophores that can rapidly and precisely monitor molecular ions relevant to environmental, biomedical, and other related areas.

  19. Active liquid-like behavior of nucleoli determines their size and shape in Xenopus laevis oocytes.

    Science.gov (United States)

    Brangwynne, Clifford P; Mitchison, Timothy J; Hyman, Anthony A

    2011-03-15

    For most intracellular structures with larger than molecular dimensions, little is known about the connection between underlying molecular activities and higher order organization such as size and shape. Here, we show that both the size and shape of the amphibian oocyte nucleolus ultimately arise because nucleoli behave as liquid-like droplets of RNA and protein, exhibiting characteristic viscous fluid dynamics even on timescales of Nucleoli exhibit a broad distribution of sizes with a characteristic power law, which we show is a consequence of spontaneous coalescence events. These results have implications for the function of nucleoli in ribosome subunit processing and provide a physical link between activity within a macromolecular assembly and its physical properties on larger length scales.

  20. Constant size descriptors for accurate machine learning models of molecular properties

    Science.gov (United States)

    Collins, Christopher R.; Gordon, Geoffrey J.; von Lilienfeld, O. Anatole; Yaron, David J.

    2018-06-01

    Two different classes of molecular representations for use in machine learning of thermodynamic and electronic properties are studied. The representations are evaluated by monitoring the performance of linear and kernel ridge regression models on well-studied data sets of small organic molecules. One class of representations studied here counts the occurrence of bonding patterns in the molecule. These require only the connectivity of atoms in the molecule as may be obtained from a line diagram or a SMILES string. The second class utilizes the three-dimensional structure of the molecule. These include the Coulomb matrix and Bag of Bonds, which list the inter-atomic distances present in the molecule, and Encoded Bonds, which encode such lists into a feature vector whose length is independent of molecular size. Encoded Bonds' features introduced here have the advantage of leading to models that may be trained on smaller molecules and then used successfully on larger molecules. A wide range of feature sets are constructed by selecting, at each rank, either a graph or geometry-based feature. Here, rank refers to the number of atoms involved in the feature, e.g., atom counts are rank 1, while Encoded Bonds are rank 2. For atomization energies in the QM7 data set, the best graph-based feature set gives a mean absolute error of 3.4 kcal/mol. Inclusion of 3D geometry substantially enhances the performance, with Encoded Bonds giving 2.4 kcal/mol, when used alone, and 1.19 kcal/mol, when combined with graph features.

  1. Effect of particle size on the glass transition.

    Science.gov (United States)

    Larsen, Ryan J; Zukoski, Charles F

    2011-05-01

    The glass transition temperature of a broad class of molecules is shown to depend on molecular size. This dependency results from the size dependence of the pair potential. A generalized equation of state is used to estimate how the volume fraction at the glass transition depends on the size of the molecule, for rigid molecule glass-formers. The model shows that at a given pressure and temperature there is a size-induced glass transition: For molecules larger than a critical size, the volume fraction required to support the effective pressure due to particle attractions is above that which characterizes the glassy state. This observation establishes the boundary between nanoparticles, which exist in liquid form only as dispersions in low molecular weight solvents and large molecules which form liquids that have viscosities below those characterized by the glassy state.

  2. Molecular dynamics simulation of bubble nucleation in explosive boiling

    International Nuclear Information System (INIS)

    Zou Yu; Chinese Academy of Sciences, Beijing; Huai Xiulan; Liang Shiqiang

    2009-01-01

    Molecular dynamics (MD) simulation is carried out for the bubble nucleation of liquid nitrogen in explosive boiling. The heat is transferred into the simulation system by rescaling the velocity of the molecules. The results indicate that the initial equilibrium temperature of liquid and molecular cluster size affect the energy conversion in the process of bubble nucleation. The potential energy of the system violently varies at the beginning of the bubble nucleation, and then varies around a fixed value. At the end of bubble nucleation, the potential energy of the system slowly increases. In the bubble nucleation of explosive boiling, the lower the initial equilibrium temperature, the larger the size of the molecular cluster, and the more the heat transferred into the system of the simulation cell, causing the increase potential energy in a larger range. (authors)

  3. Effects of molecular size and chemical factor on plasma gene transfection

    Science.gov (United States)

    Ikeda, Yoshihisa; Motomura, Hideki; Kido, Yugo; Satoh, Susumu; Jinno, Masafumi

    2016-07-01

    In order to clarify the mechanism of plasma gene transfection, the relationship between transfection efficiency and transferred molecular size was investigated. Molecules with low molecular mass (less than 50 kDa; dye or dye-labeled oligonucleotide) and high molecular mass (more than 1 MDa; plasmid DNA or fragment of plasmid DNA) were transferred to L-929 cells. It was found that the transfection efficiency decreases with increasing in transferred molecular size and also depends on the tertiary structure of transferred molecules. Moreover, it was suggested the transfection mechanism is different between the molecules with low (less than 50 kDa) and high molecular mass (higher than 1 MDa). For the amount of gene transfection after plasma irradiation, which is comparable to that during plasma irradiation, it is shown that H2O2 molecules are the main contributor. The transfection efficiency decreased to 0.40 ± 0.22 upon scavenging the H2O2 generated by plasma irradiation using the catalase. On the other hand, when the H2O2 solution is dropped into the cell suspension without plasma irradiation, the transfection efficiency is almost 0%. In these results, it is also suggested that there is a synergetic effect of H2O2 with electrical factors or other reactive species generated by plasma irradiation.

  4. The pack size effect: Influence on consumer perceptions of portion sizes

    NARCIS (Netherlands)

    Hieke, Sophie; Palascha, Aikaterini; Jola, Corinne; Wills, Josephine; Raats, Monique M.

    2016-01-01

    Larger portions as well as larger packs can lead to larger prospective consumption estimates, larger servings and increased consumption, described as 'portion-size effects' and 'pack size effects'. Although related, the effects of pack sizes on portion estimates have received less attention. While

  5. High-pressure size exclusion chromatography analysis of dissolved organic matter isolated by tangential-flow ultra filtration

    Science.gov (United States)

    Everett, C.R.; Chin, Y.-P.; Aiken, G.R.

    1999-01-01

    A 1,000-Dalton tangential-flow ultrafiltration (TFUF) membrane was used to isolate dissolved organic matter (DOM) from several freshwater environments. The TFUF unit used in this study was able to completely retain a polystyrene sulfonate 1,800-Dalton standard. Unaltered and TFUF-fractionated DOM molecular weights were assayed by high-pressure size exclusion chromatography (HPSEC). The weight-averaged molecular weights of the retentates were larger than those of the raw water samples, whereas the filtrates were all significantly smaller and approximately the same size or smaller than the manufacturer-specified pore size of the membrane. Moreover, at 280 nm the molar absorptivity of the DOM retained by the ultrafilter is significantly larger than the material in the filtrate. This observation suggests that most of the chromophoric components are associated with the higher molecular weight fraction of the DOM pool. Multivalent metals in the aqueous matrix also affected the molecular weights of the DOM molecules. Typically, proton-exchanged DOM retentates were smaller than untreated samples. This TFUF system appears to be an effective means of isolating aquatic DOM by size, but the ultimate size of the retentates may be affected by the presence of metals and by configurational properties unique to the DOM phase.

  6. Hybrid Josephson-CMOS Memory in Advanced Technologies and Larger Sizes

    International Nuclear Information System (INIS)

    Liu, Q; Van Duzer, T; Fujiwara, K; Yoshikawa, N

    2006-01-01

    Recent progress on demonstrating components of the 64 kb Josephson-CMOS hybrid memory has encouraged exploration of the advancement possible with use of advanced technologies for both the Josephson and CMOS parts of the memory, as well as considerations of the effect of memory size on access time and power dissipation. The simulations to be reported depend on the use of an approximate model for 90 nm CMOS at 4 K. This model is an extension of the one we developed for 0.25 μm CMOS and have already verified. For the Josephson parts, we have chosen 20 kA/cm 2 technology, which was recently demonstrated. The calculations show that power dissipation and access time increase rather slowly with increasing size of the memory

  7. Molecular evidence for Lessepsian invasion of soritids (larger symbiont bearing benthic foraminifera.

    Directory of Open Access Journals (Sweden)

    Gily Merkado

    Full Text Available The Mediterranean Sea is considered as one of the hotspots of marine bioinvasions, largely due to the influx of tropical species migrating through the Suez Canal, so-called Lessepsian migrants. Several cases of Lessepsian migration have been documented recently, however, little is known about the ecological characteristics of the migrating species and their aptitude to colonize the new areas. This study focused on Red Sea soritids, larger symbiont-bearing benthic foraminifera (LBF that are indicative of tropical and subtropical environments and were recently found in the Israeli coast of the Eastern Mediterranean. We combined molecular phylogenetic analyses of soritids and their algal symbionts as well as network analysis of Sorites orbiculus Forskål to compare populations from the Gulf of Elat (northern Red Sea and from a known hotspot in Shikmona (northern Israel that consists of a single population of S. orbiculus. Our phylogenetic analyses show that all specimens found in Shikmona are genetically identical to a population of S. orbiculus living on a similar shallow water pebbles habitat in the Gulf of Elat. Our analyses also show that the symbionts found in Shikmona and Elat soritids belong to the Symbiodinium clade F5, which is common in the Red Sea and also present in the Indian Ocean and Caribbean Sea. Our study therefore provides the first genetic and ecological evidences that indicate that modern population of soritids found on the Mediterranean coast of Israel is probably Lessepsian, and is less likely the descendant of a native ancient Mediterranean species.

  8. Editorial Commentary: The Larger Holes or Larger Number of Holes We Drill in the Coracoid, the Weaker the Coracoid Becomes.

    Science.gov (United States)

    Brady, Paul

    2016-06-01

    The larger holes or larger number of holes we drill in the coracoid, the weaker the coracoid becomes. Thus, minimizing bone holes (both size and number) is required to lower risk of coracoid process fracture, in patients in whom transosseous shoulder acromioclavicular joint reconstruction is indicated. A single 2.4-mm-diameter tunnel drilled through both the clavicle and the coracoid lowers the risk of fracture, but the risk cannot be entirely eliminated. Copyright © 2016 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

  9. Size and shape of soil humic acids estimated by viscosity and molecular weight.

    Science.gov (United States)

    Kawahigashi, Masayuki; Sumida, Hiroaki; Yamamoto, Kazuhiko

    2005-04-15

    Ultrafiltration fractions of three soil humic acids were characterized by viscometry and high performance size-exclusion chromatography (HPSEC) in order to estimate shapes and hydrodynamic sizes. Intrinsic viscosities under given solute/solvent/temperature conditions were obtained by extrapolating the concentration dependence of reduced viscosities to zero concentration. Molecular mass (weight average molecular weight (M (w)) and number average molecular weight (M (n))) and hydrodynamic radius (R(H)) were determined by HPSEC using pullulan as calibrant. Values of M (w) and M (n) ranged from 15 to 118 x 10(3) and from 9 to 50 x 10(3) (g mol(-1)), respectively. Polydispersity, as indicated by M (w)/M (n), increased with increasing filter size from 1.5 to 2.4. The hydrodynamic radii (R(H)) ranged between 2.2 and 6.4 nm. For each humic acid, M (w) and [eta] were related. Mark-Houwink coefficients calculated on the basis of the M (w)-[eta] relationships suggested restricted flexible chains for two of the humic acids and a branched structure for the third humic acid. Those structures probably behave as hydrated sphere colloids in a good solvent. Hydrodynamic radii of fractions calculated from [eta] using Einstein's equation, which is applicable to hydrated sphere colloids, ranged from 2.2 to 7.1 nm. These dimensions are fit to the size of nanospaces on and between clay minerals and micropores in soil particle aggregates. On the other hand, the good agreement of R(H) values obtained by applying Einstein's equation with those directly determined by HPSEC suggests that pullulan is a suitable calibrant for estimation of molecular mass and size of humic acids by HPSEC.

  10. Influence of the molecular structure on indentation size effect in polymers

    International Nuclear Information System (INIS)

    Han, Chung-Souk

    2010-01-01

    Size dependent deformation of polymers has been observed by various researchers in various experimental settings including micro beam bending, foams and indentation testing. Here in this article the indentation size effect in polymers is examined which manifests itself in increased hardness at decreasing indentation depths. Based on previously suggested rationale of size dependent deformation and depth dependent hardness model the depth dependent hardness of various polymers are analyzed. It is found that polymers containing aromatic rings in their molecular structure exhibit depth dependent hardness above the micron length scale. For polymers not containing aromatic rings polymers the indentation size effect starts at smaller indentation depths if they are present at all.

  11. Molecular sizes of lichen ice nucleation sites determined by gamma radiation inactivation analysis

    International Nuclear Information System (INIS)

    Kieft, T.L.; Ruscetti, T.

    1992-01-01

    It has previously been shown that some species of lichen fungi contain proteinaceous ice nuclei which are active at temperatures as warm as −2 °C. This experiment was undertaken to determine the molecular sizes of ice nuclei in the lichen fungus Rhizoplaca chrysoleuca and to compare them to bacterial ice nuclei from Pseudomonas syringae. Gamma radiation inactivation analysis was used to determine molecular weights. Radiation inactivation analysis is based on target theory, which states that the likelihood of a molecule being inactivated by gamma rays increases as its size increases. Three different sources of ice nuclei from the lichen R. chrysoleuca were tested: field-collected lichens, extract of lichen fungus, and a pure culture of the fungus R. chrysoleuca. P. syringae strain Cit7 was used as a source of bacterial ice nuclei. Samples were lyophilized, irradiated with gamma doses ranging from 0 to 10.4 Mrads, and then tested for ice nucleation activity using a droplet-freezing assay. Data for all four types of samples were in rough agreement; sizes of nucleation sites increased logarithmically with increasing temperatures of ice nucleation activity. Molecular weights of nucleation sites active between −3 and −4 °C from the bacteria and from the field-collected lichens were approximately 1.0 × 10 6 Da. Nuclei from the lichen fungus and in the lichen extract appeared to be slightly smaller but followed the same log-normal pattern with temperature of ice nucleation activity. The data for both the bacterial and lichen ice nuclei are in agreement with ice nucleation theory which states that the size of ice nucleation sites increases logarithmically as the temperature of nucleation increases linearly. This suggests that although some differences exist between bacterial and lichen ice nucleation sites, their molecular sizes are quite similar

  12. Why have microsaccades become larger?

    DEFF Research Database (Denmark)

    Hansen, Dan Witzner; Nyström, Marcus; Andersson, Richard

    2014-01-01

    -trackers compared to the systems used in the classical studies, in combination with the lack of a systematic algorithmic treatment of the overshoot. We hope that awareness of these discrepancies in microsaccade dynamics across eye structures will lead to more generally accepted definitions of microsaccades....... experts. The main reason was that the overshoots were not systematically detected by the algorithm and therefore not accurately accounted for. We conclude that one reason to why the reported size of microsaccades has increased is due to the larger overshoots produced by the modern pupil-based eye...

  13. Unexpected Molecular Sieving Properties of Zeolitic Imidazolate Framework-8

    KAUST Repository

    Zhang, Chen; Lively, Ryan P.; Zhang, Ke; Johnson, Justin R.; Karvan, Oguz; Koros, William J.

    2012-01-01

    We studied molecular sieving properties of zeolitic imidazolate framework-8 (ZIF-8) by estimating the thermodynamically corrected diffusivities of probe molecules at 35 °C. From helium (2.6 Å) to iso-C 4H 10 (5.0 Å), the corrected diffusivity drops 14 orders of magnitude. Our results further suggest that the effective aperture size of ZIF-8 for molecular sieving is in the range of 4.0 to 4.2 Å, which is significantly larger than the XRD-derived value (3.4 Å) and between the well-known aperture size of zeolite 4A (3.8 Å) and 5A (4.3 Å). Interestingly, because of aperture flexibility, the studied C 4 hydrocarbon molecules that are larger than this effective aperture size still adsorb in the micropores of ZIF-8 with kinetic selectivities for iso-C 4H 8/iso-C 4H 10 of 180 and n-C 4H 10/iso-C 4H 10 of 2.5 × 10 6. These unexpected molecular sieving properties open up new opportunities for ZIF materials for separations that cannot be economically achieved by traditional microporous adsorbents such as synthetic zeolites. © 2012 American Chemical Society.

  14. Unexpected Molecular Sieving Properties of Zeolitic Imidazolate Framework-8

    KAUST Repository

    Zhang, Chen

    2012-08-16

    We studied molecular sieving properties of zeolitic imidazolate framework-8 (ZIF-8) by estimating the thermodynamically corrected diffusivities of probe molecules at 35 °C. From helium (2.6 Å) to iso-C 4H 10 (5.0 Å), the corrected diffusivity drops 14 orders of magnitude. Our results further suggest that the effective aperture size of ZIF-8 for molecular sieving is in the range of 4.0 to 4.2 Å, which is significantly larger than the XRD-derived value (3.4 Å) and between the well-known aperture size of zeolite 4A (3.8 Å) and 5A (4.3 Å). Interestingly, because of aperture flexibility, the studied C 4 hydrocarbon molecules that are larger than this effective aperture size still adsorb in the micropores of ZIF-8 with kinetic selectivities for iso-C 4H 8/iso-C 4H 10 of 180 and n-C 4H 10/iso-C 4H 10 of 2.5 × 10 6. These unexpected molecular sieving properties open up new opportunities for ZIF materials for separations that cannot be economically achieved by traditional microporous adsorbents such as synthetic zeolites. © 2012 American Chemical Society.

  15. Size exclusion chromatography with superficially porous particles.

    Science.gov (United States)

    Schure, Mark R; Moran, Robert E

    2017-01-13

    A comparison is made using size-exclusion chromatography (SEC) of synthetic polymers between fully porous particles (FPPs) and superficially porous particles (SPPs) with similar particle diameters, pore sizes and equal flow rates. Polystyrene molecular weight standards with a mobile phase of tetrahydrofuran are utilized for all measurements conducted with standard HPLC equipment. Although it is traditionally thought that larger pore volume is thermodynamically advantageous in SEC for better separations, SPPs have kinetic advantages and these will be shown to compensate for the loss in pore volume compared to FPPs. The comparison metrics include the elution range (smaller with SPPs), the plate count (larger for SPPs), the rate production of theoretical plates (larger for SPPs) and the specific resolution (larger with FPPs). Advantages to using SPPs for SEC are discussed such that similar separations can be conducted faster using SPPs. SEC using SPPs offers similar peak capacities to that using FPPs but with faster operation. This also suggests that SEC conducted in the second dimension of a two-dimensional liquid chromatograph may benefit with reduced run time and with equivalently reduced peak width making SPPs advantageous for sampling the first dimension by the second dimension separator. Additional advantages are discussed for biomolecules along with a discussion of optimization criteria for size-based separations. Copyright © 2016 Elsevier B.V. All rights reserved.

  16. Effect of linear alcohol molecular size on the self-assembly of fullerene whiskers

    International Nuclear Information System (INIS)

    Amer, Maher S.; Todd, T. Kyle; Busbee, John D.

    2011-01-01

    Highlights: → The longer the alcohol molecule, the shorter the length of the assembled whisker. → Interaction between alcohol and fullerene solvent is the key factor. → The stronger the alcohol/solvent interaction, the longer the whisker. - Abstract: The recent development of self-assembled fullerene whiskers and wires has created an enormous potential and resolved a serious challenge for utilizing such unique class of carbon material in advanced nano-scale, molecular-based electronic, optical, and thermal devices. In this paper we investigate, the self-assembly of C 60 molecules into one-dimensional whiskers using a series of linear alcohols H(CH 2 ) n OH, with n changing from 1 (methanol) to 3 (isopropyl alcohol), to elucidate the effect of alcohol molecular size on the size distribution of the self-assemble fullerene whiskers. Our results show that the length of the produced fullerene whiskers is affected by the molecular size of the alcohol used in the process. The crucial role played by solvent/alcohol interaction in the assembly process is discussed. In addition, Raman spectroscopy measurements support the notion that the self-assembled whiskers are primarily held by depletion forces and no evidence of fullerene polymerization was observed.

  17. Diffusion of two-dimensional epitaxial clusters on metal (100) surfaces: Facile versus nucleation-mediated behavior and their merging for larger sizes

    International Nuclear Information System (INIS)

    Lai, King C.; Liu, Da-Jiang; Evans, James W.

    2017-01-01

    For diffusion of two-dimensional homoepitaxial clusters of N atoms on metal(100) surfaces mediated by edge atom hopping, macroscale continuum theory suggests that the diffusion coefficient scales like DN ~ N -β with β = 3/2. However, we find quite different and diverse behavior in multiple size regimes. These include: (i) facile diffusion for small sizes N < 9; (ii) slow nucleation-mediated diffusion with small β < 1 for “perfect” sizes N = N p = L 2 or L(L+1), for L = 3, 4,… having unique ground state shapes, for moderate sizes 9 ≤ N ≤ O(10 2 ); the same also applies for N = N p +3, N p + 4,… (iii) facile diffusion but with large β > 2 for N = Np + 1 and N p + 2 also for moderate sizes 9 ≤ N ≤ O(10 2 ); (iv) merging of the above distinct branches and subsequent anomalous scaling with 1 ≲ β < 3/2, reflecting the quasi-facetted structure of clusters, for larger N = O(10 2 ) to N = O(10 3 ); and (v) classic scaling with β = 3/2 for very large N = O(103) and above. The specified size ranges apply for typical model parameters. We focus on the moderate size regime where show that diffusivity cycles quasi-periodically from the slowest branch for N p + 3 (not Np) to the fastest branch for Np + 1. Behavior is quantified by Kinetic Monte Carlo simulation of an appropriate stochastic lattice-gas model. However, precise analysis must account for a strong enhancement of diffusivity for short time increments due to back-correlation in the cluster motion. Further understanding of this enhancement, of anomalous size scaling behavior, and of the merging of various branches, is facilitated by combinatorial analysis of the number of the ground state and low-lying excited state cluster configurations, and also of kink populations.

  18. Molecular-Sized DNA or RNA Sequencing Machine | NCI Technology Transfer Center | TTC

    Science.gov (United States)

    The National Cancer Institute's Gene Regulation and Chromosome Biology Laboratory is seeking statements of capability or interest from parties interested in collaborative research to co-develop a molecular-sized DNA or RNA sequencing machine.

  19. The one-sample PARAFAC approach reveals molecular size distributions of fluorescent components in dissolved organic matter

    DEFF Research Database (Denmark)

    Wünsch, Urban; Murphy, Kathleen R.; Stedmon, Colin

    2017-01-01

    Molecular size plays an important role in dissolved organic matter (DOM) biogeochemistry, but its relationship with the fluorescent fraction of DOM (FDOM) remains poorly resolved. Here high-performance size exclusion chromatography (HPSEC) was coupled to fluorescence emission-excitation (EEM...... but not their spectral properties. Thus, in contrast to absorption measurements, bulk fluorescence is unlikely to reliably indicate the average molecular size of DOM. The one-sample approach enables robust and independent cross-site comparisons without large-scale sampling efforts and introduces new analytical...... opportunities for elucidating the origins and biogeochemical properties of FDOM...

  20. Particle Size Affects Concentration-Dependent Cytotoxicity of Chitosan Nanoparticles towards Mouse Hematopoietic Stem Cells

    International Nuclear Information System (INIS)

    Zaki, S. S. O.; Ibrahim, M. N.; Katas, H.

    2015-01-01

    Chitosan nanoparticles (CSNPs) have been extensively applied in medical and pharmaceutical fields as promising drug delivery systems. Despite that, the safety of CSNPs remains inadequate and needs further investigation, particularly on hematopoietic stem cells (HSCs). CSNPs were prepared by ionic gelation method and later were characterized for their physical characteristics (particle size and zeta potential). Cytotoxicity of CSNPs was assessed by MTT assay. Particle size was highly influenced by chitosan concentration and molecular weight (medium and high molecular weight (MMW and HMW)). Higher chitosan concentration and molecular weight produced larger nanoparticles. Zeta potential of CSNPs was not significantly affected by chitosan concentrations and molecular weights used in the present study. MMW had a better stability than HMW CSNPs as their particle size and zeta potential were not significantly altered after autoclaving. Cytotoxicity of CSNPs was influenced by zeta potential and particle size. On the other hand, chitosan concentration and molecular weight indirectly influenced cytotoxicity by affecting particle size and zeta potential of CSNPs. In conclusion, cytotoxicity of CSNPs was mainly attributed to their physical characteristics and this opens a strategy to ensure the safety of CSNPs applications in stem cell technology.

  1. Electronic shift register memory based on molecular electron-transfer reactions

    Science.gov (United States)

    Hopfield, J. J.; Onuchic, Jose Nelson; Beratan, David N.

    1989-01-01

    The design of a shift register memory at the molecular level is described in detail. The memory elements are based on a chain of electron-transfer molecules incorporated on a very large scale integrated (VLSI) substrate, and the information is shifted by photoinduced electron-transfer reactions. The design requirements for such a system are discussed, and several realistic strategies for synthesizing these systems are presented. The immediate advantage of such a hybrid molecular/VLSI device would arise from the possible information storage density. The prospect of considerable savings of energy per bit processed also exists. This molecular shift register memory element design solves the conceptual problems associated with integrating molecular size components with larger (micron) size features on a chip.

  2. Larger Bowl Size Increases the Amount of Cereal Children Request, Consume, and Waste

    NARCIS (Netherlands)

    Wansink, Brian; van Ittersum, Koert; Payne, Collin R.

    Objective To examine whether larger bowls bias children toward requesting more food from the adults who serve them. Study design Study 1 was a between-subject design involving 69 preschool-age children who were randomized to receive either a small (8 oz) or large (16 oz) cereal bowl and were asked

  3. Understanding the Synthesis and Properties of Molecular Silver Nanoparticles

    Science.gov (United States)

    Ashenfelter, Brian A.

    Molecular nanoparticles have emerged as an interesting class of materials whose atomically precise structures and discrete properties set them apart from their larger counterparts. Molecular silver nanoparticles are of particular interest because they provide a host of advantages as optical materials for possible use in sensing and imaging applications. However, relatively little is known about molecular silver nanoparticles including the details of their formation and their optical and mechanical properties. Size control remains a longstanding challenge in the production of glutathionate (SG) protected silver nanoparticles. Singular Ag:SG nanoparticle products have been difficult to obtain directly, but size focusing of larger distributions through attrition has been found to lead to useful isolation of particular species. Here, we present a methodology for controlling the size of Ag:SG molecular nanoparticles that leverages the stability of the most robust species. These results were then used to develop a facile approach for achieving two of the most stable species in the Ag:SG system. Molecular metal nanoparticles are known to be much more fluorescent than larger plasmonic nanoparticles, however the nature and origin of this fluorescence are not fully understood. Fluorescence can originate from either the quantum states within the metal core or mixed ligand states at the inorganic-organic interface. We have presented compelling evidence that fluorescence from molecular silver glutathionate nanoparticles has its origin in interfacial electronic states. Fluorescence spectra were found to be independent of size, with very similar wavelength and bandwidth, although the quantum yield was not. Excitation spectra indicated that the strongest fluorescence had its origin in that part of the spectrum that is dominated by ligand-related states. Further, excitations to strictly core states and to higher lying d-band states had little to no contribution to the fluorescence

  4. Dairy farmers with larger herd sizes adopt more precision dairy technologies.

    Science.gov (United States)

    Gargiulo, J I; Eastwood, C R; Garcia, S C; Lyons, N A

    2018-06-01

    An increase in the average herd size on Australian dairy farms has also increased the labor and animal management pressure on farmers, thus potentially encouraging the adoption of precision technologies for enhanced management control. A survey was undertaken in 2015 in Australia to identify the relationship between herd size, current precision technology adoption, and perception of the future of precision technologies. Additionally, differences between farmers and service providers in relation to perception of future precision technology adoption were also investigated. Responses from 199 dairy farmers, and 102 service providers, were collected between May and August 2015 via an anonymous Internet-based questionnaire. Of the 199 dairy farmer responses, 10.4% corresponded to farms that had fewer than 150 cows, 37.7% had 151 to 300 cows, 35.5% had 301 to 500 cows; 6.0% had 501 to 700 cows, and 10.4% had more than 701 cows. The results showed that farmers with more than 500 cows adopted between 2 and 5 times more specific precision technologies, such as automatic cup removers, automatic milk plant wash systems, electronic cow identification systems and herd management software, when compared with smaller farms. Only minor differences were detected in perception of the future of precision technologies between either herd size or farmers and service providers. In particular, service providers expected a higher adoption of automatic milking and walk over weighing systems than farmers. Currently, the adoption of precision technology has mostly been of the type that reduces labor needs; however, respondents indicated that by 2025 adoption of data capturing technology for monitoring farm system parameters would be increased. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  5. Bioavailability of Carbon Nanomaterial-Adsorbed Polycyclic Aromatic Hydrocarbons to Pimphales promelas: Influence of Adsorbate Molecular Size and Configuration.

    Science.gov (United States)

    Linard, Erica N; Apul, Onur G; Karanfil, Tanju; van den Hurk, Peter; Klaine, Stephen J

    2017-08-15

    Despite carbon nanomaterials' (CNMs) potential to alter the bioavailability of adsorbed contaminants, information characterizing the relationship between adsorption behavior and bioavailability of CNM-adsorbed contaminants is still limited. To investigate the influence of CNM morphology and organic contaminant (OC) physicochemical properties on this relationship, adsorption isotherms were generated for a suite of polycyclic aromatic hydrocarbons (PAHs) on multiwalled carbon nanotubes (MWCNTs) and exfoliated graphene (GN) in conjunction with determining the bioavailability of the adsorbed PAHs to Pimphales promelas using bile analysis via fluorescence spectroscopy. Although it appeared that GN adsorbed PAHs indiscriminately compared to MWCNTs, the subsequent bioavailability of GN-adsorbed PAHs was more sensitive to PAH morphology than MWCNTs. GN was effective at reducing bioavailability of linear PAHs by ∼70%, but had little impact on angular PAHs. MWCNTs were sensitive to molecular size, where bioavailability of two-ringed naphthalene was reduced by ∼80%, while bioavailability of the larger PAHs was reduced by less than 50%. Furthermore, the reduction in bioavailability of CNM-adsorbed PAHs was negatively correlated with the amount of CNM surface area covered by the adsorbed-PAHs. This study shows that the variability in bioavailability of CNM-adsorbed PAHs is largely driven by PAH size, configuration and surface area coverage.

  6. Experiments for the Undergraduate Laboratory that Illustrate the Size-Exclusion Properties of Zeolite Molecular Sieves

    Science.gov (United States)

    Cooke, Jason; Henderson, Eric J.

    2009-01-01

    Experiments are presented that demonstrate the size-exclusion properties of zeolites and reveal the reason for naming zeolites "molecular sieves". If an IR spectrometer is available, the adsorption or exclusion of alcohols of varying sizes from dichloromethane or chloroform solutions can be readily demonstrated by monitoring changes in the…

  7. Visual exposure to large and small portion sizes and perceptions of portion size normality: Three experimental studies.

    Science.gov (United States)

    Robinson, Eric; Oldham, Melissa; Cuckson, Imogen; Brunstrom, Jeffrey M; Rogers, Peter J; Hardman, Charlotte A

    2016-03-01

    Portion sizes of many foods have increased in recent times. In three studies we examined the effect that repeated visual exposure to larger versus smaller food portion sizes has on perceptions of what constitutes a normal-sized food portion and measures of portion size selection. In studies 1 and 2 participants were visually exposed to images of large or small portions of spaghetti bolognese, before making evaluations about an image of an intermediate sized portion of the same food. In study 3 participants were exposed to images of large or small portions of a snack food before selecting a portion size of snack food to consume. Across the three studies, visual exposure to larger as opposed to smaller portion sizes resulted in participants considering a normal portion of food to be larger than a reference intermediate sized portion. In studies 1 and 2 visual exposure to larger portion sizes also increased the size of self-reported ideal meal size. In study 3 visual exposure to larger portion sizes of a snack food did not affect how much of that food participants subsequently served themselves and ate. Visual exposure to larger portion sizes may adjust visual perceptions of what constitutes a 'normal' sized portion. However, we did not find evidence that visual exposure to larger portions altered snack food intake. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Song repertoire size correlates with measures of body size in Eurasian blackbirds

    DEFF Research Database (Denmark)

    Hesler, Nana; Mundry, Roger; Sacher, Thomas

    2012-01-01

    In most oscine bird species males possess a repertoire of different song patterns. The size of these repertoires is assumed to serve as an honest signal of male quality. The Eurasian blackbird’s (Turdus merula) song contains a large repertoire of different element types with a flexible song...... organisation. Here we investigated whether repertoire size in Eurasian blackbirds correlates with measures of body size, namely length of wing, 8th primary, beak and tarsus. So far, very few studies have investigated species with large repertoires and a flexible song organisation in this context. We found...... positive correlations, meaning that larger males had larger repertoires. Larger males may have better fighting abilities and, thus, advantages in territorial defence. Larger structural body size may also reflect better conditions during early development. Therefore, under the assumption that body size...

  9. Trees of unusual size: biased inference of early bursts from large molecular phylogenies.

    Directory of Open Access Journals (Sweden)

    Matthew W Pennell

    Full Text Available An early burst of speciation followed by a subsequent slowdown in the rate of diversification is commonly inferred from molecular phylogenies. This pattern is consistent with some verbal theory of ecological opportunity and adaptive radiations. One often-overlooked source of bias in these studies is that of sampling at the level of whole clades, as researchers tend to choose large, speciose clades to study. In this paper, we investigate the performance of common methods across the distribution of clade sizes that can be generated by a constant-rate birth-death process. Clades which are larger than expected for a given constant-rate branching process tend to show a pattern of an early burst even when both speciation and extinction rates are constant through time. All methods evaluated were susceptible to detecting this false signature when extinction was low. Under moderate extinction, both the [Formula: see text]-statistic and diversity-dependent models did not detect such a slowdown but only because the signature of a slowdown was masked by subsequent extinction. Some models which estimate time-varying speciation rates are able to detect early bursts under higher extinction rates, but are extremely prone to sampling bias. We suggest that examining clades in isolation may result in spurious inferences that rates of diversification have changed through time.

  10. Tunable separations based on a molecular size effect for biomolecules by poly(ethylene glycol) gel-based capillary electrophoresis.

    Science.gov (United States)

    Kubo, Takuya; Nishimura, Naoki; Furuta, Hayato; Kubota, Kei; Naito, Toyohiro; Otsuka, Koji

    2017-11-10

    We report novel capillary gel electrophoresis (CGE) with poly(ethylene glycol) (PEG)-based hydrogels for the effective separations of biomolecules containing sugars and DNAs based on a molecular size effect. The gel capillaries were prepared in a fused silica capillary modified with 3-(trimethoxysilyl)propylmethacrylate using a variety of the PEG-based hydrogels. After the fundamental evaluations in CGE regarding the separation based on the molecular size effect depending on the crosslinking density, the optimized capillary provided the efficient separation of glucose ladder (G1 to G20). In addition, another capillary showed the successful separation of DNA ladder in the range of 10-1100 base pair, which is superior to an authentic acrylamide-based gel capillary. For both glucose and DNA ladders, the separation ranges against the molecular size were simply controllable by alteration of the concentration and/or units of ethylene oxide in the PEG-based crosslinker. Finally, we demonstrated the separations of real samples, which included sugars carved out from monoclonal antibodies, mAbs, and then the efficient separations based on the molecular size effect were achieved. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Surgical outcome of primary clipping for anterior circulation aneurysms of size 2 centimeters or larger.

    Science.gov (United States)

    Furtado, Sunil V; Saikiran, Narayanam A; Thakar, Sumit; Dadlani, Ravi; Mohan, Dilip; Aryan, Saritha; Hegde, Alangar S

    2014-07-01

    Aneurysms of the anterior circulation larger than 2cm have a complex relationship to the anterior skull base, requiring a multi-modality management approach. This retrospective study of 54 patients with such aneurysms who underwent clipping between 2001 and 2012 analyzes clinical and surgical data, aneurysm characteristics and correlates them with respect to the Glasgow outcome score at follow-up and immediate post-operative clinical status. Patients with an outcome score of 5 or 4 were categorized as "good", while those with score 3-1 were "poor". Fisher's exact test and paired T-test (p<0.5) were used to test statistical significance for discrete and continuous variables respectively. 44 (81.4%) patients had a good outcome. Patients with non-ophthalmic/paraclinoid aneurysms had significantly lower incidence of adverse intra-operative events (p=0.035). Patients older than 50 years (p=0.045), with adverse intra-operative events (p=0.015) and post-operative infarction (p<0.001) had a poor outcome compared to those younger than 50 years age and those without adverse intra-operative events or infarctions. The grouped age variable had maximum influence on patient outcome. Location and size of aneurysm did not have an overall impact on surgical outcome. There were 4 mortalities. Primary clipping of proximal non-cavernous aneurysms on the internal carotid artery is associated with adverse intra-operative events. A multi-modality treatment approach in these aneurysms should be individualized, more so in patients older than 50 years. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. SME routes for innovation collaboration with larger enterprises

    DEFF Research Database (Denmark)

    Brink, Tove

    2017-01-01

    The research in this paper reveals how Small and Medium-sized Enterprises (SMEs) can contribute to industry competiveness through collaboration with larger enterprises. The research is based on a longitudinal qualitative case study starting in 2011 with 10 SME offshore wind farm suppliers...... and follow-up interviews in 2013. The research continued with a second approach in 2014 within operation and maintenance (O&M) through focus group interviews and subsequent individual interviews with 20 enterprises and a seminar in May 2015. The findings reveal opportunities and challenges for SMEs according...... to three different routes for cooperation and collaboration with larger enterprises: demand-driven cooperation, supplier-driven cooperation and partnerdriven collaboration. The SME contribution to innovation and competiveness is different within the three routes and ranges from providing specific knowledge...

  13. Demonstrating the value of larger ensembles in forecasting physical systems

    Directory of Open Access Journals (Sweden)

    Reason L. Machete

    2016-12-01

    Full Text Available Ensemble simulation propagates a collection of initial states forward in time in a Monte Carlo fashion. Depending on the fidelity of the model and the properties of the initial ensemble, the goal of ensemble simulation can range from merely quantifying variations in the sensitivity of the model all the way to providing actionable probability forecasts of the future. Whatever the goal is, success depends on the properties of the ensemble, and there is a longstanding discussion in meteorology as to the size of initial condition ensemble most appropriate for Numerical Weather Prediction. In terms of resource allocation: how is one to divide finite computing resources between model complexity, ensemble size, data assimilation and other components of the forecast system. One wishes to avoid undersampling information available from the model's dynamics, yet one also wishes to use the highest fidelity model available. Arguably, a higher fidelity model can better exploit a larger ensemble; nevertheless it is often suggested that a relatively small ensemble, say ~16 members, is sufficient and that larger ensembles are not an effective investment of resources. This claim is shown to be dubious when the goal is probabilistic forecasting, even in settings where the forecast model is informative but imperfect. Probability forecasts for a ‘simple’ physical system are evaluated at different lead times; ensembles of up to 256 members are considered. The pure density estimation context (where ensemble members are drawn from the same underlying distribution as the target differs from the forecasting context, where one is given a high fidelity (but imperfect model. In the forecasting context, the information provided by additional members depends also on the fidelity of the model, the ensemble formation scheme (data assimilation, the ensemble interpretation and the nature of the observational noise. The effect of increasing the ensemble size is quantified by

  14. Kepler Mission: a Discovery-Class Mission Designed to Determine the Frequency of Earth-Size and Larger Planets Around Solar-Like Stars

    Science.gov (United States)

    Borucki, William; Koch, David; Lissauer, Jack; Basri, Gibor; Caldwell, John; Cochran, William; Dunham, Edward W.; Gilliland, Ronald; Caldwell, Douglas; Kondo, Yoji; hide

    2002-01-01

    The first step in discovering the extent of life in our galaxy is to determine the number of terrestrial planets in the habitable zone (HZ). The Kepler Mission is designed around a 0.95 in aperture Schmidt-type telescope with an array of 42 CCDs designed to continuously monitor the brightness of 100,000 solar-like stars to detect the transits of Earth-size and larger planets. The photometer is scheduled to be launched into heliocentric orbit in 2007. Measurements of the depth and repetition time of transits provide the size of the planet relative to the star and its orbital period. When combined with ground-based spectroscopy of these stars to fix the stellar parameters, the true planet radius and orbit scale, hence the position relative to the HZ are determined. These spectra are also used to discover the relationships between the characteristics of planets and the stars they orbit. In particular, the association of planet size and occurrence frequency with stellar mass and metallicity will be investigated. At the end of the four year mission, hundreds of terrestrial planets should be discovered in and near the HZ of their stars if such planets are common. Extending the mission to six years doubles the expected number of Earth-size planets in the HZ. A null result would imply that terrestrial planets in the HZ occur in less than 1% of the stars and that life might be quite rare. Based on the results of the current Doppler-velocity discoveries, detection of a thousand giant planets is expected. Information on their albedos and densities of those giants showing transits will be obtained.

  15. Rates of molecular evolution in tree ferns are associated with body size, environmental temperature, and biological productivity.

    Science.gov (United States)

    Barrera-Redondo, Josué; Ramírez-Barahona, Santiago; Eguiarte, Luis E

    2018-05-01

    Variation in rates of molecular evolution (heterotachy) is a common phenomenon among plants. Although multiple theoretical models have been proposed, fundamental questions remain regarding the combined effects of ecological and morphological traits on rate heterogeneity. Here, we used tree ferns to explore the correlation between rates of molecular evolution in chloroplast DNA sequences and several morphological and environmental factors within a Bayesian framework. We revealed direct and indirect effects of body size, biological productivity, and temperature on substitution rates, where smaller tree ferns living in warmer and less productive environments tend to have faster rates of molecular evolution. In addition, we found that variation in the ratio of nonsynonymous to synonymous substitution rates (dN/dS) in the chloroplast rbcL gene was significantly correlated with ecological and morphological variables. Heterotachy in tree ferns may be influenced by effective population size associated with variation in body size and productivity. Macroevolutionary hypotheses should go beyond explaining heterotachy in terms of mutation rates and instead, should integrate population-level factors to better understand the processes affecting the tempo of evolution at the molecular level. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

  16. Association of radionuclides with different molecular size fractions in soil solution: implications for plant uptake

    International Nuclear Information System (INIS)

    Nisbet, A.F.; Shaw, S.; Salbu, B.

    1993-01-01

    The feasibility of using hollow fibre ultrafiltration to determine the molecular size distribution of radionuclides in soil solution was investigated. The physical and chemical composition of soil plays a vital role in determining radionuclide uptake by plant roots. Soil solution samples were extracted from loam, peat and sand soils that had been artificially contaminated with 137 Cs, 90 Sr, 239 Pu and 241 Am six years previously as part of a five-year lysimeter study on radionuclide uptake to crops. Ultrafiltration of soil solution was performed using hollow fibre cartridges with a nominal molecular weight cut off of 3 and 10 kD. The association of 137 Cs, 90 Sr, 239 Pu and 241 Am with different molecular size fractions of the soil solution is discussed in terms of radionuclide bioavailability to cabbage grown in the same three soils. 137 Cs and 90 Sr were present in low molecular weight forms and as such were mobile in soil and potentially available for uptake by the cabbage. In contrast, a large proportion (61-87%) of the 239 Pu and 241 Am were associated with colloidal and high molecular weight material and therefore less available for uptake by plant roots. The contribution from low molecular weight species of 239 Pu and 241 Am to the total activity in soil solution decreased in the order loam ≥ peat ≥ sand. Association of radionuclides with low molecular weight species of less than 3 kD did not, however, automatically imply availability to plants. (author)

  17. Molecular size evolution of oligomers in organic aerosols collected in urban atmospheres and generated in a smog chamber.

    Science.gov (United States)

    Kalberer, Markus; Sax, Mirjam; Samburova, Vera

    2006-10-01

    Only a minor fraction of the total organic aerosol mass can be resolved on a molecular level. High molecular weight compounds in organic aerosols have recently gained much attention because this class of compound potentially explains a major fraction of the unexplained organic aerosol mass. These compounds have been identified with different mass spectrometric methods, and compounds with molecular masses up to 1000 Da are found in secondary organic aerosols (SOA) generated from aromatic and terpene precursors in smog chamber experiments. Here, we apply matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) to SOA particles from two biogenic precursors, alpha-pinene and isoprene. Similar oligomer patterns are found in these two SOA systems, but also in SOA from trimethylbenzene, an anthropogenic SOA precursor. However, different maxima molecular sizes were measured for these three SOA systems. While oligomers in alpha-pinene and isoprene have sizes mostly below 600-700 Da, they grow up to about 1000 Da in trimethylbenzene-SOA. The final molecular size of the oligomers is reached early during the particle aging process, whereas other particle properties related to aging, such as the overall acid concentration or the oligomer concentration, increase continuously over a much longer time scale. This kinetic behavior of the oligomer molecular size growth can be explained by a chain growth kinetic regime. Similar oligomer mass patterns were measured in aqueous extracts of ambient aerosol samples (measured with the same technique). Distinct differences between summer and winter were observed. In summer a few single mass peaks were measured with much higher intensity than in winter, pointing to a possible difference in the formation processes of these compounds in winter and summer.

  18. Comparable investigation of the molecular size distribution and the amount of humic substances isolated from ONKALO, Olkiluoto, 2011

    International Nuclear Information System (INIS)

    Luste, S.; Maekelae, J.; Manninen, P.

    2012-06-01

    The humic substances (HS) at groundwater from ONKALO, Olkiluoto were studied in order to determine the apparent molecular size distribution and the amount of humic substances. Humic substances were isolated from the water sample using DAX-8 resin and eluted with 0.1 M NaOH. The molecular size distribution was defined using high performance size exclusion chromatography (HPSEC) and ultraviolet (UV) and refractive index (RI) detector. In the SEC calibration (polystyrene sulfonate) sodium salts (PSS) were employed. Different eluents (NaNO 3 , Na-acetate and asetonitrile) with phosphate buffer and distinct ionic strengths were studied in order to optimize the determination method. The amount of humic substances was determined using total organic carbon (TOC) measurements. The results were compared with the previous ones in order to find out the variation of different methods (HPSEC) and to follow up the HS quantity (TOC). The method developed during the study is considered to be suitable for the HS molecular size distribution follow up, although the method development is suggested to be continued. (orig.)

  19. Comparable investigation of the molecular size distribution and the amount of humic substances isolated from ONKALO, Olkiluoto, 2011

    Energy Technology Data Exchange (ETDEWEB)

    Luste, S.; Maekelae, J.; Manninen, P. [Ramboll Finland Oy, Espoo (Finland)

    2012-06-15

    The humic substances (HS) at groundwater from ONKALO, Olkiluoto were studied in order to determine the apparent molecular size distribution and the amount of humic substances. Humic substances were isolated from the water sample using DAX-8 resin and eluted with 0.1 M NaOH. The molecular size distribution was defined using high performance size exclusion chromatography (HPSEC) and ultraviolet (UV) and refractive index (RI) detector. In the SEC calibration (polystyrene sulfonate) sodium salts (PSS) were employed. Different eluents (NaNO{sub 3}, Na-acetate and asetonitrile) with phosphate buffer and distinct ionic strengths were studied in order to optimize the determination method. The amount of humic substances was determined using total organic carbon (TOC) measurements. The results were compared with the previous ones in order to find out the variation of different methods (HPSEC) and to follow up the HS quantity (TOC). The method developed during the study is considered to be suitable for the HS molecular size distribution follow up, although the method development is suggested to be continued. (orig.)

  20. Unicortical critical size defect of rabbit tibia is larger than 8 mm

    DEFF Research Database (Denmark)

    Aaboe, M; Pinholt, E M; Hjørting-Hansen, E

    1994-01-01

    The critical-size defect is important as an experimental model to test bone repair materials. Guided tissue regeneration is an established method for tissue regeneration within periodontal surgery. Bony defects covered by a membrane are allowed to be filled by bony tissue. Healing of 8-mm...

  1. Size-dependent single electron transfer and semi-metal-to-insulator transitions in molecular metal oxide electronics

    Science.gov (United States)

    Balliou, Angelika; Bouroushian, Mirtat; Douvas, Antonios M.; Skoulatakis, George; Kennou, Stella; Glezos, Nikos

    2018-07-01

    All-inorganic self-arranged molecular transition metal oxide hyperstructures based on polyoxometalate molecules (POMs) are fabricated and tested as electronically tunable components in emerging electronic devices. POM hyperstructures reveal great potential as charging nodes of tunable charging level for molecular memories and as enhancers of interfacial electron/hole injection for photovoltaic stacks. STM, UPS, UV–vis spectroscopy and AFM measurements show that this functionality stems from the films’ ability to structurally tune their HOMO–LUMO levels and electron localization length at room temperature. By adapting POM nanocluster size in solution, self-doping and current modulation of four orders of magnitude is monitored on a single nanocluster on SiO2 at voltages as low as 3 Volt. Structurally driven insulator-to-semi-metal transitions and size-dependent current regulation through single electron tunneling are demonstrated and examined with respect to the stereochemical and electronic structure of the molecular entities. This extends the value of self-assembly as a tool for correlation length and electronic properties tuning and demonstrate POM hyperstructures’ plausibility for on-chip molecular electronics operative at room temperature.

  2. Size-dependent single electron transfer and semi-metal-to-insulator transitions in molecular metal oxide electronics.

    Science.gov (United States)

    Balliou, Angelika; Bouroushian, Mirtat; Douvas, Antonios M; Skoulatakis, George; Kennou, Stella; Glezos, Nikos

    2018-07-06

    All-inorganic self-arranged molecular transition metal oxide hyperstructures based on polyoxometalate molecules (POMs) are fabricated and tested as electronically tunable components in emerging electronic devices. POM hyperstructures reveal great potential as charging nodes of tunable charging level for molecular memories and as enhancers of interfacial electron/hole injection for photovoltaic stacks. STM, UPS, UV-vis spectroscopy and AFM measurements show that this functionality stems from the films' ability to structurally tune their HOMO-LUMO levels and electron localization length at room temperature. By adapting POM nanocluster size in solution, self-doping and current modulation of four orders of magnitude is monitored on a single nanocluster on SiO 2 at voltages as low as 3 Volt. Structurally driven insulator-to-semi-metal transitions and size-dependent current regulation through single electron tunneling are demonstrated and examined with respect to the stereochemical and electronic structure of the molecular entities. This extends the value of self-assembly as a tool for correlation length and electronic properties tuning and demonstrate POM hyperstructures' plausibility for on-chip molecular electronics operative at room temperature.

  3. Coalescence preference and droplet size inequality during fluid phase segregation

    Science.gov (United States)

    Roy, Sutapa

    2018-02-01

    Using molecular dynamics simulations and scaling arguments, we investigate the coalescence preference dynamics of liquid droplets in a phase-segregating off-critical, single-component fluid. It is observed that the preferential distance of the product drop from its larger parent, during a coalescence event, gets smaller for large parent size inequality. The relative coalescence position exhibits a power-law dependence on the parent size ratio with an exponent q ≃ 3.1 . This value of q is in strong contrast with earlier reports 2.1 and 5.1 in the literature. The dissimilarity is explained by considering the underlying coalescence mechanisms.

  4. Standard Practice for Continuous Sizing and Counting of Airborne Particles in Dust-Controlled Areas and Clean Rooms Using Instruments Capable of Detecting Single Sub-Micrometre and Larger Particles

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 This practice covers the determination of the particle concentration, by number, and the size distribution of airborne particles in dust-controlled areas and clean rooms, for particles in the size range of approximately 0.01 to 5.0 m. Particle concentrations not exceeding 3.5 106 particles/m3 (100 000/ft 3) are covered for all particles equal to and larger than the minimum size measured. 1.2 This practice uses an airborne single particle counting device (SPC) whose operation is based on measuring the signal produced by an individual particle passing through the sensing zone. The signal must be directly or indirectly related to particle size. Note 1The SPC type is not specified here. The SPC can be a conventional optical particle counter (OPC), an aerodynamic particle sizer, a condensation nucleus counter (CNC) operating in conjunction with a diffusion battery or differential mobility analyzer, or any other device capable of counting and sizing single particles in the size range of concern and of sampling...

  5. Container size influences snack food intake independently of portion size.

    Science.gov (United States)

    Marchiori, David; Corneille, Olivier; Klein, Olivier

    2012-06-01

    While larger containers have been found to increase food intake, it is unclear whether this effect is driven by container size, portion size, or their combination, as these variables are usually confounded. The study was advertised as examining the effects of snack food consumption on information processing and participants were served M&M's for free consumption in individual cubicles while watching a TV show. Participants were served (1) a medium portion of M&M's in a small (n=30) or (2) in a large container (n=29), or (3) a large portion in a large container (n=29). The larger container increased intake by 129% (199 kcal) despite holding portion size constant, while controlling for different confounding variables. This research suggests that larger containers stimulate food intake over and above their impact on portion size. Copyright © 2012 Elsevier Ltd. All rights reserved.

  6. [Determination of the distribution of relative molecular mass of organic matter by high pressure size exclusion chromatography with UV and TOC detectors].

    Science.gov (United States)

    Zhang, Han; Dong, Bing-Zhi

    2012-09-01

    An on-line high pressure size exclusion chromatography (HPSEC) with UV and TOC detectors was adapted to examine the distribution of relative molecular mass of natural organic matter (NOM). Through synchronous determination of UV254 and TOC responses in a wide range of relative molecular mass, it was possible to accurately characterize the structure of NOM, especially for some non-aromatic and non-conjugated double bond organics which have low response to UV. It was found that, TOC detector was capable of detecting all kinds of organic matters, including sucrose, sodium alginate and other hydrophilic organic compounds. The sample volume had a positively linear correlation with the TOC response, indicating that the larger volume would produce stronger responses. The effect of ion strength was relatively low, shown by the small decrease of peak area (1.2% ) from none to 0.2 mol x L(-1) NaCl. The pH value of tested samples should be adjusted to neutral or acidic because when the samples were alkaline, the results might be inaccurate. Compared to the sample solvents adopted as ultrapure water, the samples prepared by mobile phase solvents had less interference to salt boundary peak. The on-line HPSEC-UV-TOC can be used accurately to characterize the distribution of relative molecular mass and its four fractions in River Xiang.

  7. Squamate hatchling size and the evolutionary causes of negative offspring size allometry.

    Science.gov (United States)

    Meiri, S; Feldman, A; Kratochvíl, L

    2015-02-01

    Although fecundity selection is ubiquitous, in an overwhelming majority of animal lineages, small species produce smaller number of offspring per clutch. In this context, egg, hatchling and neonate sizes are absolutely larger, but smaller relative to adult body size in larger species. The evolutionary causes of this widespread phenomenon are not fully explored. The negative offspring size allometry can result from processes limiting maximal egg/offspring size forcing larger species to produce relatively smaller offspring ('upper limit'), or from a limit on minimal egg/offspring size forcing smaller species to produce relatively larger offspring ('lower limit'). Several reptile lineages have invariant clutch sizes, where females always lay either one or two eggs per clutch. These lineages offer an interesting perspective on the general evolutionary forces driving negative offspring size allometry, because an important selective factor, fecundity selection in a single clutch, is eliminated here. Under the upper limit hypotheses, large offspring should be selected against in lineages with invariant clutch sizes as well, and these lineages should therefore exhibit the same, or shallower, offspring size allometry as lineages with variable clutch size. On the other hand, the lower limit hypotheses would allow lineages with invariant clutch sizes to have steeper offspring size allometries. Using an extensive data set on the hatchling and female sizes of > 1800 species of squamates, we document that negative offspring size allometry is widespread in lizards and snakes with variable clutch sizes and that some lineages with invariant clutch sizes have unusually steep offspring size allometries. These findings suggest that the negative offspring size allometry is driven by a constraint on minimal offspring size, which scales with a negative allometry. © 2014 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2014 European Society For Evolutionary

  8. Functional and physical molecular size of the chicken hepatic lectin determined by radiation inactivation and sedimentation equilibrium analysis

    International Nuclear Information System (INIS)

    Steer, C.J.; Osborne, J.C. Jr.; Kempner, E.S.

    1990-01-01

    Radiation inactivation and sedimentation equilibrium analysis were used to determine the functional and physical size of the chicken hepatic membrane receptor that binds N-acetylglucosamine-terminated glycoproteins. Purified plasma membranes from chicken liver were irradiated with high energy electrons and assayed for 125I-agalactoorosomucoid binding. Increasing the dose of ionizing radiation resulted in a monoexponential decay in binding activity due to a progressive loss of binding sites. The molecular mass of the chicken lectin, determined in situ by target analysis, was 69,000 +/- 9,000 Da. When the same irradiated membranes were solubilized in Brij 58 and assayed, the binding protein exhibited a target size of 62,000 +/- 4,000 Da; in Triton X-100, the functional size of the receptor was 85,000 +/- 10,000 Da. Sedimentation equilibrium measurements of the purified binding protein yielded a lower limit molecular weight of 79,000 +/- 7,000. However, the solubilized lectin was detected as a heterogeneous population of oligomers with molecular weights as high as 450,000. Addition of calcium or calcium plus N-acetylglucosamine decreased the higher molecular weight species, but the lower limit molecular weights remained invariant. Similar results were determined when the chicken lectin was solubilized in Brij 58, C12E9, or 3-[(3-cholamidopropyl)dimethylammonio]-1-propane-sulfonic acid (CHAPS). Results from the present study suggest that in the plasma membrane, the functional species of the chicken hepatic lectin exists as a trimer. However, in detergent solution, the purified receptor forms a heterogeneous population of irreversible oligomers that exhibit binding activity proportional to size

  9. Kepler Mission: A Wide-FOV Photometer Designed to Determine the Frequency of Earth-Size and Larger Planets Around Solar-like stars

    Science.gov (United States)

    Borucki, William; Koch, David; Lissauer, Jack; Basri, Gibor; Caldwell, John; Cochran, William; Dunham, Edward W.; Gilliland, Ronald; Jenkins, Jon M.; Caldwell, Douglas; hide

    2002-01-01

    The first step in discovering the extent of life in our galaxy is to determine the number of terrestrial planets in the habitable zone (HZ). The Kepler Mission is designed around a 0.95 m aperture Schmidt-type telescope with an array of 42 CCDs designed to continuously monitor the brightness of 100,000 solar-like stars to detect the transits of Earth-size and larger planets. The photometer is scheduled to be launched into heliocentric orbit in 2007. Measurements of the depth and repetition time of transits provide the size of the planet relative to the star and its orbital period. When combined with ground-based spectroscopy of these stars to fix the stellar parameters, the true planet radius and orbit scale, hence the position relative to the HZ are determined. These spectra are also used to discover the relationships between the characteristics of planets and the stars they orbit. In particular, the association of planet size and occurrence frequency with stellar mass and metallicity will be investigated. At the end of the four year mission, hundreds of terrestrial planets should be discovered in and near the HZ of their stars if such planets are common. A null result would imply that terrestrial planets in the HZ occur in less than 1% of the stars and that life might be quite rare. Based on the results of the current doppler-velocity discoveries, detection of a thousand giant planets is expected. Information on their albedos and densities of those giants showing transits will be obtained.

  10. Quantitative structure-activity relationship (QSAR) models for polycyclic aromatic hydrocarbons (PAHs) dissipation in rhizosphere based on molecular structure and effect size

    International Nuclear Information System (INIS)

    Ma Bin; Chen Huaihai; Xu Minmin; Hayat, Tahir; He Yan; Xu Jianming

    2010-01-01

    Rhizoremediation is a significant form of bioremediation for polycyclic aromatic hydrocarbons (PAHs). This study examined the role of molecular structure in determining the rhizosphere effect on PAHs dissipation. Effect size in meta-analysis was employed as activity dataset for building quantitative structure-activity relationship (QSAR) models and accumulative effect sizes of 16 PAHs were used for validation of these models. Based on the genetic algorithm combined with partial least square regression, models for comprehensive dataset, Poaceae dataset, and Fabaceae dataset were built. The results showed that information indices, calculated as information content of molecules based on the calculation of equivalence classes from the molecular graph, were the most important molecular structural indices for QSAR models of rhizosphere effect on PAHs dissipation. The QSAR model, based on the molecular structure indices and effect size, has potential to be used in studying and predicting the rhizosphere effect of PAHs dissipation. - Effect size based on meta-analysis was used for building PAHs dissipation quantitative structure-activity relationship (QSAR) models.

  11. Quantitative structure-activity relationship (QSAR) models for polycyclic aromatic hydrocarbons (PAHs) dissipation in rhizosphere based on molecular structure and effect size

    Energy Technology Data Exchange (ETDEWEB)

    Ma Bin; Chen Huaihai; Xu Minmin; Hayat, Tahir [Zhejiang Provincial Key Laboratory of Subtropical Soil and Plant Nutrition, College of Environmental and Natural Resource Sciences, Zhejiang University, Hangzhou 310029 (China); He Yan, E-mail: yhe2006@zju.edu.c [Zhejiang Provincial Key Laboratory of Subtropical Soil and Plant Nutrition, College of Environmental and Natural Resource Sciences, Zhejiang University, Hangzhou 310029 (China); Xu Jianming, E-mail: jmxu@zju.edu.c [Zhejiang Provincial Key Laboratory of Subtropical Soil and Plant Nutrition, College of Environmental and Natural Resource Sciences, Zhejiang University, Hangzhou 310029 (China)

    2010-08-15

    Rhizoremediation is a significant form of bioremediation for polycyclic aromatic hydrocarbons (PAHs). This study examined the role of molecular structure in determining the rhizosphere effect on PAHs dissipation. Effect size in meta-analysis was employed as activity dataset for building quantitative structure-activity relationship (QSAR) models and accumulative effect sizes of 16 PAHs were used for validation of these models. Based on the genetic algorithm combined with partial least square regression, models for comprehensive dataset, Poaceae dataset, and Fabaceae dataset were built. The results showed that information indices, calculated as information content of molecules based on the calculation of equivalence classes from the molecular graph, were the most important molecular structural indices for QSAR models of rhizosphere effect on PAHs dissipation. The QSAR model, based on the molecular structure indices and effect size, has potential to be used in studying and predicting the rhizosphere effect of PAHs dissipation. - Effect size based on meta-analysis was used for building PAHs dissipation quantitative structure-activity relationship (QSAR) models.

  12. On the validity of the Navier-Stokes equations for nanoscale liquid flows: The role of channel size

    Directory of Open Access Journals (Sweden)

    Chong Liu

    2011-09-01

    Full Text Available In this work, we investigate the validity of the Navier-Stokes (NS equations for nanoscale liquid flows through molecular dynamics simulations. We focus on the role of channel size by considering the fluid-wall interaction. Liquid flows between two planar parallel walls driven by an external force with channel size ranging from 2 to 80 nm are studied. The volumetric flux is computed and the dependence of the volumetric flux on the channel size is explained both qualitatively and quantitatively. It is found that the flow is sensitive to the fluid-wall binding energy and the classical fluid mechanics falls apart in small nanochannels. However, the wall effects become insignificant and the NS equations are valid when the channel size is larger than about 150 molecular diameters (∼ 50 nm.

  13. Comparison between smaller ruptured intracranial aneurysm and larger un-ruptured intracranial aneurysm: gene expression profile analysis.

    Science.gov (United States)

    Li, Hao; Li, Haowen; Yue, Haiyan; Wang, Wen; Yu, Lanbing; ShuoWang; Cao, Yong; Zhao, Jizong

    2017-07-01

    As it grows in size, an intracranial aneurysm (IA) is prone to rupture. In this study, we compared two extreme groups of IAs, ruptured IAs (RIAs) smaller than 10 mm and un-ruptured IAs (UIAs) larger than 10 mm, to investigate the genes involved in the facilitation and prevention of IA rupture. The aneurismal walls of 6 smaller saccular RIAs (size smaller than 10 mm), 6 larger saccular UIAs (size larger than 10 mm) and 12 paired control arteries were obtained during surgery. The transcription profiles of these samples were studied by microarray analysis. RT-qPCR was used to confirm the expression of the genes of interest. In addition, functional group analysis of the differentially expressed genes was performed. Between smaller RIAs and larger UIAs, 101 genes and 179 genes were significantly over-expressed, respectively. In addition, functional group analysis demonstrated that the up-regulated genes in smaller RIAs mainly participated in the cellular response to metal ions and inorganic substances, while most of the up-regulated genes in larger UIAs were involved in inflammation and extracellular matrix (ECM) organization. Moreover, compared with control arteries, inflammation was up-regulated and muscle-related biological processes were down-regulated in both smaller RIAs and larger UIAs. The genes involved in the cellular response to metal ions and inorganic substances may facilitate the rupture of IAs. In addition, the healing process, involving inflammation and ECM organization, may protect IAs from rupture.

  14. Larger men have larger prostates: Detection bias in epidemiologic studies of obesity and prostate cancer risk.

    Science.gov (United States)

    Rundle, Andrew; Wang, Yun; Sadasivan, Sudha; Chitale, Dhananjay A; Gupta, Nilesh S; Tang, Deliang; Rybicki, Benjamin A

    2017-06-01

    Obesity is associated with risk of aggressive prostate cancer (PCa), but not with over-all PCa risk. However, obese men have larger prostates which may lower biopsy accuracy and cause a systematic bias toward the null in epidemiologic studies of over-all risk. Within a cohort of 6692 men followed-up after a biopsy or transurethral resection of the prostate (TURP) with benign findings, a nested case-control study was conducted of 495 prostate cancer cases and controls matched on age, race, follow-up duration, biopsy versus TURP, and procedure date. Data on body mass index and prostate volume at the time of the initial procedure were abstracted from medical records. Prior to consideration of differences in prostate volume, overweight (OR = 1.41; 95%CI 1.01, 1.97), and obese status (OR = 1.59; 95%CI 1.09, 2.33) at the time of the original benign biopsy or TURP were associated with PCa incidence during follow-up. Prostate volume did not significantly moderate the association between body-size and PCa, however it did act as an inverse confounder; adjustment for prostate volume increased the effect size for overweight by 22% (adjusted OR = 1.52; 95%CI 1.08, 2.14) and for obese status by 23% (adjusted OR = 1.77; 95%CI 1.20, 2.62). Larger prostate volume at the time of the original benign biopsy or TURP was inversely associated with PCa incidence during follow-up (OR = 0.92 per 10 cc difference in volume; 95%CI 0.88, 0.97). In analyses that stratified case-control pairs by tumor aggressiveness of the case, prostate volume acted as an inverse confounder in analyses of non-aggressive PCa but not in analyses of aggressive PCa. In studies of obesity and PCa, differences in prostate volume cause a bias toward the null, particularly in analyses of non-aggressive PCa. A pervasive underestimation of the association between obesity and overall PCa risk may exist in the literature. © 2017 Wiley Periodicals, Inc.

  15. Nanometer size wear debris generated from ultra high molecular weight polyethylene in vivo

    Czech Academy of Sciences Publication Activity Database

    Lapčíková, Monika; Šlouf, Miroslav; Dybal, Jiří; Zolotarevova, E.; Entlicher, G.; Pokorný, D.; Gallo, J.; Sosna, A.

    2009-01-01

    Roč. 266, 1-2 (2009), s. 349-355 ISSN 0043-1648 R&D Projects: GA MŠk 2B06096 Institutional research plan: CEZ:AV0Z40500505 Keywords : ultra high molecular weight polyethylene * nanometer size wear debris * morphology of wear particles Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.771, year: 2009

  16. Particle size dependence of biogenic secondary organic aerosol molecular composition

    Science.gov (United States)

    Tu, Peijun; Johnston, Murray V.

    2017-06-01

    Formation of secondary organic aerosol (SOA) is initiated by the oxidation of volatile organic compounds (VOCs) in the gas phase whose products subsequently partition to the particle phase. Non-volatile molecules have a negligible evaporation rate and grow particles at their condensation rate. Semi-volatile molecules have a significant evaporation rate and grow particles at a much slower rate than their condensation rate. Particle phase chemistry may enhance particle growth if it transforms partitioned semi-volatile molecules into non-volatile products. In principle, changes in molecular composition as a function of particle size allow non-volatile molecules that have condensed from the gas phase (a surface-limited process) to be distinguished from those produced by particle phase reaction (a volume-limited process). In this work, SOA was produced by β-pinene ozonolysis in a flow tube reactor. Aerosol exiting the reactor was size-selected with a differential mobility analyzer, and individual particle sizes between 35 and 110 nm in diameter were characterized by on- and offline mass spectrometry. Both the average oxygen-to-carbon (O / C) ratio and carbon oxidation state (OSc) were found to decrease with increasing particle size, while the relative signal intensity of oligomers increased with increasing particle size. These results are consistent with oligomer formation primarily in the particle phase (accretion reactions, which become more favored as the volume-to-surface-area ratio of the particle increases). Analysis of a series of polydisperse SOA samples showed similar dependencies: as the mass loading increased (and average volume-to-surface-area ratio increased), the average O / C ratio and OSc decreased, while the relative intensity of oligomer ions increased. The results illustrate the potential impact that particle phase chemistry can have on biogenic SOA formation and the particle size range where this chemistry becomes important.

  17. Particle size dependence of biogenic secondary organic aerosol molecular composition

    Directory of Open Access Journals (Sweden)

    P. Tu

    2017-06-01

    Full Text Available Formation of secondary organic aerosol (SOA is initiated by the oxidation of volatile organic compounds (VOCs in the gas phase whose products subsequently partition to the particle phase. Non-volatile molecules have a negligible evaporation rate and grow particles at their condensation rate. Semi-volatile molecules have a significant evaporation rate and grow particles at a much slower rate than their condensation rate. Particle phase chemistry may enhance particle growth if it transforms partitioned semi-volatile molecules into non-volatile products. In principle, changes in molecular composition as a function of particle size allow non-volatile molecules that have condensed from the gas phase (a surface-limited process to be distinguished from those produced by particle phase reaction (a volume-limited process. In this work, SOA was produced by β-pinene ozonolysis in a flow tube reactor. Aerosol exiting the reactor was size-selected with a differential mobility analyzer, and individual particle sizes between 35 and 110 nm in diameter were characterized by on- and offline mass spectrometry. Both the average oxygen-to-carbon (O ∕ C ratio and carbon oxidation state (OSc were found to decrease with increasing particle size, while the relative signal intensity of oligomers increased with increasing particle size. These results are consistent with oligomer formation primarily in the particle phase (accretion reactions, which become more favored as the volume-to-surface-area ratio of the particle increases. Analysis of a series of polydisperse SOA samples showed similar dependencies: as the mass loading increased (and average volume-to-surface-area ratio increased, the average O ∕ C ratio and OSc decreased, while the relative intensity of oligomer ions increased. The results illustrate the potential impact that particle phase chemistry can have on biogenic SOA formation and the particle size range where this chemistry becomes

  18. Size and molecular weight determination of polysaccharides by means of nano electrospray gas-phase electrophoretic mobility molecular analysis (nES GEMMA).

    Science.gov (United States)

    Weiss, Victor U; Golesne, Monika; Friedbacher, Gernot; Alban, Susanne; Szymanski, Wladyslaw W; Marchetti-Deschmann, Martina; Allmaier, Günter

    2018-02-21

    Size, size distribution and molecular weight (MW) determination of nanoparticles and that are for example large polymers, are of great interest and pose an analytical challenge. In this context, nano electrospray gas-phase electrophoretic mobility molecular analysis (nES GEMMA) is a valuable tool with growing impact. Separation of single-charged analytes according to their electrophoretic mobility diameter (EMD) starting from single-digit EMDs up to several hundred nm diameters is possible. In case of spherical analytes, the EMD corresponds to the dry nanoparticle size. Additionally, the instrument is capable of number-based, single-particle detection following the recommendation of the European Commission for nanoparticle characterization (2011/696/EU). In case an EMD/MW correlation for a particular compound class (based on availability of well-defined standards) exists, a nanoparticle's MW can be determined from its EMD. In the present study, we focused on nES GEMMA of linear and branched, water-soluble polysaccharides forming nanoparticles and were able to obtain spectra for both analyte classes regarding single-charged species. Based on EMDs for corresponding analytes, an excellent EMD/MW correlation could be obtained in case of the branched natural polymer (dextran). This enables the determination of dextran MWs from nES GEMMA spectra despite high analyte polydispersity and in a size/MW range, where classical mass spectrometry is limited. EMD/MW correlations based on linear (pullulans, oat-ß-glucans) polymers were significantly different, possibly indicating challenges in the exact MW determination of these compounds by, for example, chromatographic and light scattering means. Despite these observations, nES GEMMA of linear, monosaccharide-based polymers enabled the determination of size and size-distribution of such dry bionanoparticles. © 2018 The Authors. Electrophoresis published by Wiley-VCH Verlag GmbH & Co. KGaA.

  19. A Caenorhabditis elegans wild type defies the temperature-size rule owing to a single nucleotide polymorphism in tra-3.

    Directory of Open Access Journals (Sweden)

    Jan E Kammenga

    2007-03-01

    Full Text Available Ectotherms rely for their body heat on surrounding temperatures. A key question in biology is why most ectotherms mature at a larger size at lower temperatures, a phenomenon known as the temperature-size rule. Since temperature affects virtually all processes in a living organism, current theories to explain this phenomenon are diverse and complex and assert often from opposing assumptions. Although widely studied, the molecular genetic control of the temperature-size rule is unknown. We found that the Caenorhabditis elegans wild-type N2 complied with the temperature-size rule, whereas wild-type CB4856 defied it. Using a candidate gene approach based on an N2 x CB4856 recombinant inbred panel in combination with mutant analysis, complementation, and transgenic studies, we show that a single nucleotide polymorphism in tra-3 leads to mutation F96L in the encoded calpain-like protease. This mutation attenuates the ability of CB4856 to grow larger at low temperature. Homology modelling predicts that F96L reduces TRA-3 activity by destabilizing the DII-A domain. The data show that size adaptation of ectotherms to temperature changes may be less complex than previously thought because a subtle wild-type polymorphism modulates the temperature responsiveness of body size. These findings provide a novel step toward the molecular understanding of the temperature-size rule, which has puzzled biologists for decades.

  20. Protecting the larger fish: an ecological, economical and evolutionary analysis using a demographic model

    DEFF Research Database (Denmark)

    Verdiell, Nuria Calduch

    . Recently, there is increasing evidence that this size-selective fishing reduces the chances of maintaining populations at levels sufficient to produce maximum sustainable yields, the chances of recovery/rebuilding populations that have been depleted/collapsed and may causes rapid evolutionary changes...... and the consequent changes in yield. We attempt to evaluate the capability of the larger fish to mitigate the evolutionary change on life-history traits caused by fishing, while also maintaining a sustainable annual yield. This is achieved by calculating the expected selection response on three life-history traits......Many marine fish stocks are reported as overfished on a global scale. This overfishing not only removes fish biomass, but also causes dramatic changes in the age and size structure of fish stocks. In particular, targeting of the larger individuals truncates the age and size structure of stocks...

  1. Size and composition dependence of the frozen structures in Co-based bimetallic clusters

    International Nuclear Information System (INIS)

    Li, Guojian; Wang, Qiang; Cao, Yongze; Du, Jiaojiao; He, Jicheng

    2012-01-01

    This Letter studies the size-dependent freezing of Co, Co–Ni, and Co–Cu clusters by using molecular dynamics with embedded atom method. Size effect occurs in these three types of clusters. The clusters with large sizes always freeze to form their bulk-like structures. However, the frozen structures for small sizes are generally related to their compositions. The icosahedral clusters are formed for Co clusters (for ⩽3.2 nm diameter) and also for Co–Ni clusters but at a larger size range (for ⩽4.08 nm). Upon the Co–Cu clusters, decahedral structure is obtained for small size (for 2.47 nm). The released energy induced the structural transformation plays a key role in the frozen structures. These results indicate that the preformed clusters with special structures can be tuned by controlling their compositions and sizes. -- Highlights: ► The size effect occurs in the Co, Co–Ni, and Co–Cu clusters. ► The clusters with large sizes always freeze to form their bulk-like structures. ► The frozen structures for small sizes are generally related to their compositions. ► Icosahedron is formed for Co and also for Co–Ni but at a larger size range. ► Upon the Co–Cu clusters, decahedral structure is obtained for small size.

  2. Density-functional errors in ionization potential with increasing system size

    Energy Technology Data Exchange (ETDEWEB)

    Whittleton, Sarah R.; Sosa Vazquez, Xochitl A.; Isborn, Christine M., E-mail: cisborn@ucmerced.edu [Chemistry and Chemical Biology, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California 95343 (United States); Johnson, Erin R., E-mail: erin.johnson@dal.ca [Chemistry and Chemical Biology, School of Natural Sciences, University of California, Merced, 5200 North Lake Road, Merced, California 95343 (United States); Department of Chemistry, Dalhousie University, 6274 Coburg Road, Halifax, Nova Scotia B3H 4R2 (Canada)

    2015-05-14

    This work investigates the effects of molecular size on the accuracy of density-functional ionization potentials for a set of 28 hydrocarbons, including series of alkanes, alkenes, and oligoacenes. As the system size increases, delocalization error introduces a systematic underestimation of the ionization potential, which is rationalized by considering the fractional-charge behavior of the electronic energies. The computation of the ionization potential with many density-functional approximations is not size-extensive due to excessive delocalization of the incipient positive charge. While inclusion of exact exchange reduces the observed errors, system-specific tuning of long-range corrected functionals does not generally improve accuracy. These results emphasize that good performance of a functional for small molecules is not necessarily transferable to larger systems.

  3. The Larger Linear N-Heteroacenes

    KAUST Repository

    Bunz, Uwe H. F.

    2015-01-01

    © 2015 American Chemical Society. ConspectusThe close structural and chemical relationship of N-heteroacenes to pentacene suggests their broad applicability in organic electronic devices, such as thin-film transistors. The superb materials science properties of azaacenes result from their improved resistance toward oxidation and their potential for electron transport, both of which have been demonstrated recently. The introduction of nitrogen atoms into the aromatic perimeter of acenes stabilizes their frontier molecular orbitals and increases their electron affinity. The HOMO-LUMO gaps in azaacenes in which the nitrogen atoms are symmetrically placed are similar to those of the acenes. The judiciously placed nitrogen atoms induce an "umpolung" of the electronic behavior of these pentacene-like molecules, i.e., instead of hole mobility in thin-film transistors, azaacenes are electron-transporting materials. The fundamental synthetic approaches toward larger azaacenes are described and discussed. Several synthetic methodologies have been exploited, and some have been newly developed to assemble substituted azaacenes. The oldest methods are condensation-based. Aromatic o-diamines are coupled with o-dihydroxyarenes in the melt without solvent. This method works well for unsubstituted azaacenes only. The attachment of substituents to the starting materials renders these "fire and sword" methods less useful. The starting materials decompose under these conditions. The direct condensation of substituted o-diamines with o-quinones proceeds well in some cases. Fluorinated benzene rings next to a pyrazine unit are introduced by nucleophilic aromatic substitution employing hexafluorobenzene. However, with these well-established synthetic methodologies, a number of azaacene topologies cannot be synthesized. The Pd-catalyzed coupling of aromatic halides and aromatic diamines has therefore emerged as versatile tool for azaacene synthesis. Now substituted diaza- and

  4. The Larger Linear N-Heteroacenes

    KAUST Repository

    Bunz, Uwe H. F.

    2015-06-16

    © 2015 American Chemical Society. ConspectusThe close structural and chemical relationship of N-heteroacenes to pentacene suggests their broad applicability in organic electronic devices, such as thin-film transistors. The superb materials science properties of azaacenes result from their improved resistance toward oxidation and their potential for electron transport, both of which have been demonstrated recently. The introduction of nitrogen atoms into the aromatic perimeter of acenes stabilizes their frontier molecular orbitals and increases their electron affinity. The HOMO-LUMO gaps in azaacenes in which the nitrogen atoms are symmetrically placed are similar to those of the acenes. The judiciously placed nitrogen atoms induce an "umpolung" of the electronic behavior of these pentacene-like molecules, i.e., instead of hole mobility in thin-film transistors, azaacenes are electron-transporting materials. The fundamental synthetic approaches toward larger azaacenes are described and discussed. Several synthetic methodologies have been exploited, and some have been newly developed to assemble substituted azaacenes. The oldest methods are condensation-based. Aromatic o-diamines are coupled with o-dihydroxyarenes in the melt without solvent. This method works well for unsubstituted azaacenes only. The attachment of substituents to the starting materials renders these "fire and sword" methods less useful. The starting materials decompose under these conditions. The direct condensation of substituted o-diamines with o-quinones proceeds well in some cases. Fluorinated benzene rings next to a pyrazine unit are introduced by nucleophilic aromatic substitution employing hexafluorobenzene. However, with these well-established synthetic methodologies, a number of azaacene topologies cannot be synthesized. The Pd-catalyzed coupling of aromatic halides and aromatic diamines has therefore emerged as versatile tool for azaacene synthesis. Now substituted diaza- and

  5. Size-dependent penetrant diffusion in polymer glasses.

    Science.gov (United States)

    Meng, Dong; Zhang, Kai; Kumar, Sanat K

    2018-05-18

    Molecular Dynamics simulations are used to understand the underpinning basis of the transport of gas-like solutes in deeply quenched polymeric glasses. As found in previous work, small solutes, with sizes smaller than 0.15 times the chain monomer size, move as might be expected in a medium with large pores. In contrast, the motion of larger solutes is activated and is strongly facilitated by matrix motion. In particular, solute motion is coupled to the local elastic fluctuations of the matrix as characterized by the Debye-Waller factor. While similar ideas have been previously proposed for the viscosity of supercooled liquids above their glass transition, to our knowledge, this is the first illustration of this concept in the context of solute mass transport in deeply quenched polymer glasses.

  6. A Splash to Nano-Sized Inorganic Energy-Materials by the Low-Temperature Molecular Precursor Approach.

    Science.gov (United States)

    Driess, Matthias; Panda, Chakadola; Menezes, Prashanth Wilfried

    2018-05-07

    The low-temperature synthesis of inorganic materials and their interfaces at the atomic and molecular level provides numerous opportunities for the design and improvement of inorganic materials in heterogeneous catalysis for sustainable chemical energy conversion or other energy-saving areas. Using suitable molecular precursors for functional inorganic nanomaterial synthesis allows for facile control over uniform particle size distribution, stoichiometry, and leads to desired chemical and physical properties. This minireview outlines some advantages of the molecular precursor approach in light of selected recent developments of molecule-to-nanomaterials synthesis for renewable energy applications, relevant for the oxygen evolution reaction (OER), hydrogen evolution reaction (HER) and overall water-splitting. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Lactone size dependent reactivity in Candida antarctica lipase B: A molecular dynamics and docking study

    NARCIS (Netherlands)

    Veld, M.A.J.; Fransson, L.; Palmans, A.R.A.; Meijer, E.W.; Hult, K.

    2009-01-01

    Size matters: Lactones have extensively been studied as monomers in enzymatic polymerization reactions. Large lactones showed an unexpectedly high reactivity in these reactions. A combination of docking and molecular dynamics studies have been used to explain this high reactivity in terms of

  8. Insights into the role of protein molecule size and structure on interfacial properties using designed sequences

    Science.gov (United States)

    Dwyer, Mirjana Dimitrijev; He, Lizhong; James, Michael; Nelson, Andrew; Middelberg, Anton P. J.

    2013-01-01

    Mixtures of a large, structured protein with a smaller, unstructured component are inherently complex and hard to characterize at interfaces, leading to difficulties in understanding their interfacial behaviours and, therefore, formulation optimization. Here, we investigated interfacial properties of such a mixed system. Simplicity was achieved using designed sequences in which chemical differences had been eliminated to isolate the effect of molecular size and structure, namely a short unstructured peptide (DAMP1) and its longer structured protein concatamer (DAMP4). Interfacial tension measurements suggested that the size and bulk structuring of the larger molecule led to much slower adsorption kinetics. Neutron reflectometry at equilibrium revealed that both molecules adsorbed as a monolayer to the air–water interface (indicating unfolding of DAMP4 to give a chain of four connected DAMP1 molecules), with a concentration ratio equal to that in the bulk. This suggests the overall free energy of adsorption is equal despite differences in size and bulk structure. At small interfacial extensional strains, only molecule packing influenced the stress response. At larger strains, the effect of size became apparent, with DAMP4 registering a higher stress response and interfacial elasticity. When both components were present at the interface, most stress-dissipating movement was achieved by DAMP1. This work thus provides insights into the role of proteins' molecular size and structure on their interfacial properties, and the designed sequences introduced here can serve as effective tools for interfacial studies of proteins and polymers. PMID:23303222

  9. Size and number of DNA molecules from Chinese hamster ovary cells determined by molecular autoradiography

    International Nuclear Information System (INIS)

    Todd, M.B.

    1980-06-01

    A new method for visualization of separable subunits of DNA is described. Autoradiography of tritium-labeled DNA from one or a few nuclei, lysed with detergent, moderate salt, and proteases, and gently deposited on a filter, allows determination of subunit molecular weight, size distribution, number per nucleus, and organization. The shape of the size distribution of CHO subunit images is similar to that of CHO mitotic chromosomes, and the numbers of subunits per nucleus supports a model of eight subunits per chromosome

  10. Equilibrium partitioning of macromolecules in confining geometries: Improved universality with a new molecular size parameter

    DEFF Research Database (Denmark)

    Wang, Yanwei; Peters, Günther H.J.; Hansen, Flemming Yssing

    2008-01-01

    structures (CABS), allows the computation of equilibrium partition coefficients as a function of confinement size solely based on a single sampling of the configuration space of a macromolecule in bulk. Superior in computational speed to previous computational methods, CABS is capable of handling slits...... parameter for characterization of spatial confinement effects on macromolecules. Results for the equilibrium partition coefficient in the weak confinement regime depend only on the ratio ofR-s to the confinement size regardless of molecular details....

  11. Action video game players and deaf observers have larger Goldmann visual fields.

    Science.gov (United States)

    Buckley, David; Codina, Charlotte; Bhardwaj, Palvi; Pascalis, Olivier

    2010-03-05

    We used Goldmann kinetic perimetry to compare how training and congenital auditory deprivation may affect the size of the visual field. We measured the ability of action video game players and deaf observers to detect small moving lights at various locations in the central (around 30 degrees from fixation) and peripheral (around 60 degrees ) visual fields. Experiment 1 found that 10 habitual video game players showed significantly larger central and peripheral field areas than 10 controls. In Experiment 2 we found that 13 congenitally deaf observers had significantly larger visual fields than 13 hearing controls for both the peripheral and central fields. Here the greatest differences were found in the lower parts of the fields. Comparison of the two groups showed that whereas VGP players have a more uniform increase in field size in both central and peripheral fields deaf observers show non-uniform increases with greatest increases in lower parts of the visual field.

  12. Larger groups of passerines are more efficient problem solvers in the wild

    Science.gov (United States)

    Morand-Ferron, Julie; Quinn, John L.

    2011-01-01

    Group living commonly helps organisms face challenging environmental conditions. Although a known phenomenon in humans, recent findings suggest that a benefit of group living in animals generally might be increased innovative problem-solving efficiency. This benefit has never been demonstrated in a natural context, however, and the mechanisms underlying improved efficiency are largely unknown. We examined the problem-solving performance of great and blue tits at automated devices and found that efficiency increased with flock size. This relationship held when restricting the analysis to naive individuals, demonstrating that larger groups increased innovation efficiency. In addition to this effect of naive flock size, the presence of at least one experienced bird increased the frequency of solving, and larger flocks were more likely to contain experienced birds. These findings provide empirical evidence for the “pool of competence” hypothesis in nonhuman animals. The probability of success also differed consistently between individuals, a necessary condition for the pool of competence hypothesis. Solvers had a higher probability of success when foraging with a larger number of companions and when using devices located near rather than further from protective tree cover, suggesting a role for reduced predation risk on problem-solving efficiency. In contrast to traditional group living theory, individuals joining larger flocks benefited from a higher seed intake, suggesting that group living facilitated exploitation of a novel food source through improved problem-solving efficiency. Together our results suggest that both ecological and social factors, through reduced predation risk and increased pool of competence, mediate innovation in natural populations. PMID:21930936

  13. Larger eggs in resident brown trout living in sympatry with anadromous brown trout

    DEFF Research Database (Denmark)

    Olofsson, H.; Mosegaard, Henrik

    1999-01-01

    Freshwater resident brown trout (Salmo trutta L.) in the stream Jorlandaan (southwestern Sweden) had larger eggs (range of actual mean egg wet weights, 65.9-108.5 mg) than both sympatric migratory trout (76.8-84.2 mg) and trout from five other Swedish streams with allopatric resident (23.7-80.1 mg......) or migratory populations (44.5-121.9 mg), after accounting for differences in body size. In Jorlandaan, some resident females even had a larger absolute mean egg weight than any of the migratory females found in the stream Resident trout had low absolute fecundity, and our data suggest that resident females...... in Jorlandan produce large eggs at the expense of their fecundity The extremely large relative egg size in resident Jorlandaan females suggests that the production of large offspring enhances fitness, possibly through increased fry survival....

  14. The relations between forest fragmentation and bird community body size and biodiversity and bird community body size.

    OpenAIRE

    Hopman, F.

    2017-01-01

    Bachelor thesis Future Planet Studies, major biologie ABSTRACT Animal species with a larger body-size tend to have larger home ranges than small-bodied animals. Therefore it is likely that they are more affected by habitat fragmentation than small-bodied species. Body size of birds also seems to have a negative relation with species richness. This research has therefore looked into whether birds with a larger body-size are more sensitive to habitat fragmentation caused by forest...

  15. Cooling rate and size effects on the medium-range structure of multicomponent oxide glasses simulated by molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Tilocca, Antonio [Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (United Kingdom)

    2013-09-21

    A set of molecular dynamics simulations were performed to investigate the effect of cooling rate and system size on the medium-range structure of melt-derived multicomponent silicate glasses, represented by the quaternary 45S5 Bioglass composition. Given the significant impact of the glass degradation on applications of these materials in biomedicine and nuclear waste disposal, bulk structural features which directly affect the glass dissolution process are of particular interest. Connectivity of the silicate matrix, ion clustering and nanosegregation, distribution of ring and chain structural patterns represent critical features in this context, which can be directly extracted from the models. A key issue is represented by the effect of the computational approach on the corresponding glass models, especially in light of recent indications questioning the suitability of conventional MD approaches (that is, involving melt-and-quench of systems containing ∼10{sup 3} atoms at cooling rates of 5-10 K/ps) when applied to model these glasses. The analysis presented here compares MD models obtained with conventional and nonconventional cooling rates and system sizes, highlighting the trend and range of convergence of specific structural features in the medium range. The present results show that time-consuming computational approaches involving much lower cooling rates and/or significantly larger system sizes are in most cases not necessary in order to obtain a reliable description of the medium-range structure of multicomponent glasses. We identify the convergence range for specific properties and use them to discuss models of several glass compositions for which a possible influence of cooling-rate or size effects had been previously hypothesized. The trends highlighted here represent an important reference to obtain reliable models of multicomponent glasses and extract converged medium-range structural features which affect the glass degradation and thus their

  16. Cooling rate and size effects on the medium-range structure of multicomponent oxide glasses simulated by molecular dynamics

    International Nuclear Information System (INIS)

    Tilocca, Antonio

    2013-01-01

    A set of molecular dynamics simulations were performed to investigate the effect of cooling rate and system size on the medium-range structure of melt-derived multicomponent silicate glasses, represented by the quaternary 45S5 Bioglass composition. Given the significant impact of the glass degradation on applications of these materials in biomedicine and nuclear waste disposal, bulk structural features which directly affect the glass dissolution process are of particular interest. Connectivity of the silicate matrix, ion clustering and nanosegregation, distribution of ring and chain structural patterns represent critical features in this context, which can be directly extracted from the models. A key issue is represented by the effect of the computational approach on the corresponding glass models, especially in light of recent indications questioning the suitability of conventional MD approaches (that is, involving melt-and-quench of systems containing ∼10 3 atoms at cooling rates of 5-10 K/ps) when applied to model these glasses. The analysis presented here compares MD models obtained with conventional and nonconventional cooling rates and system sizes, highlighting the trend and range of convergence of specific structural features in the medium range. The present results show that time-consuming computational approaches involving much lower cooling rates and/or significantly larger system sizes are in most cases not necessary in order to obtain a reliable description of the medium-range structure of multicomponent glasses. We identify the convergence range for specific properties and use them to discuss models of several glass compositions for which a possible influence of cooling-rate or size effects had been previously hypothesized. The trends highlighted here represent an important reference to obtain reliable models of multicomponent glasses and extract converged medium-range structural features which affect the glass degradation and thus their application

  17. Comparable investigation of the molecular size distribution and the amount of humic substances isolated from ONKALO, Olkiluoto, 2010

    International Nuclear Information System (INIS)

    Vilhunen, S.; Manninen, P.

    2010-11-01

    The humic substances at groundwater from Onkalo, Olkiluoto were studied in order to determine the molecular size distribution and the amount of humic substances. Humic substances were isolated from the water sample using DAX-8 resin and eluted with 0.1 M NaOH. The molecular size distribution was defined using high performance size exclusion chromatography (HPSEC) and ultraviolet (UV) or reflactive index (RI) detector. Two calibration standard sets (poly(styrene sulfonate) sodium salt (PSS) or polyethylene glycol (PEG) standards) with distinct structures as well as two eluents (0.05 M NaNO3 or 0.01 M Na-acetate) were studied and the results were compared with the previous ones. The calibration standards and eluents were found to have major effect on the measured parameters. The amount of humic substances was determined using total organic carbon (TOC) measurements. (orig.)

  18. Residue contacts predicted by evolutionary covariance extend the application of ab initio molecular replacement to larger and more challenging protein folds

    Directory of Open Access Journals (Sweden)

    Felix Simkovic

    2016-07-01

    Full Text Available For many protein families, the deluge of new sequence information together with new statistical protocols now allow the accurate prediction of contacting residues from sequence information alone. This offers the possibility of more accurate ab initio (non-homology-based structure prediction. Such models can be used in structure solution by molecular replacement (MR where the target fold is novel or is only distantly related to known structures. Here, AMPLE, an MR pipeline that assembles search-model ensembles from ab initio structure predictions (`decoys', is employed to assess the value of contact-assisted ab initio models to the crystallographer. It is demonstrated that evolutionary covariance-derived residue–residue contact predictions improve the quality of ab initio models and, consequently, the success rate of MR using search models derived from them. For targets containing β-structure, decoy quality and MR performance were further improved by the use of a β-strand contact-filtering protocol. Such contact-guided decoys achieved 14 structure solutions from 21 attempted protein targets, compared with nine for simple Rosetta decoys. Previously encountered limitations were superseded in two key respects. Firstly, much larger targets of up to 221 residues in length were solved, which is far larger than the previously benchmarked threshold of 120 residues. Secondly, contact-guided decoys significantly improved success with β-sheet-rich proteins. Overall, the improved performance of contact-guided decoys suggests that MR is now applicable to a significantly wider range of protein targets than were previously tractable, and points to a direct benefit to structural biology from the recent remarkable advances in sequencing.

  19. Dust captures effectiveness of scrubber systems on mechanical miners operating in larger roadways.

    CSIR Research Space (South Africa)

    Hole, BJ

    1998-03-01

    Full Text Available The project was directed towards bord and pillar working by mechanised miners operating in larger section roadways, where the problem of scrubber capture tends to be greatest owing to the limited size of the zone of influence around exhaust...

  20. Study on Size-Dependent Young’s Modulus of a Silicon Nano beam by Molecular Dynamics Simulation

    International Nuclear Information System (INIS)

    Yu, H.; Sun, C.; Zhang, W.W.; Lei, S.Y.; Huang, K.A.

    2013-01-01

    Young’s modulus of a silicon nano beam with a rectangular cross-section is studied by molecular dynamics method. Dynamic simulations are performed for doubly clamped silicon nano beams with lengths ranging from 4.888 to 12.491 nm and cross-sections ranging from 1.22 nm ×1.22 nm to 3.39 nm × 3.39 nm. The results show that Young’s moduli of such small silicon nano beams are much higher than the value of Young’s modulus for bulk silicon. Moreover, the resonant frequency and Young’s modulus of the Si nano beam are strongly dependent not only on the size of the nano beam but also on surface effects. Young’s modulus increases significantly with the decreasing of the thickness of the silicon nano beam. This result qualitatively agrees with one of the conclusions based on a semi continuum model, in which the surface relaxation and the surface tension were taken into consideration. The impacts of the surface reconstruction with (2 ×1) dimmers on the resonant frequency and Young’s modulus are studied in this paper too. It is shown that the surface reconstruction makes the silicon nano beam stiffer than the one without the surface reconstruction, resulting in a higher resonant frequency and a larger Young’s modulus

  1. Portion size and intended consumption. Evidence for a pre-consumption portion size effect in males?

    Science.gov (United States)

    Robinson, Eric; te Raa, Wesselien; Hardman, Charlotte A

    2015-08-01

    Larger portions increase energy intake (the 'portion size effect'); however, the mechanisms behind this effect are unclear. Although pre-meal intentions are thought to be an important determinant of energy intake, little research has examined how much of a meal individuals intend to eat when served standard versus larger portion sizes. Three studies examined the effect of manipulating portion size on intended food consumption. In Studies 1 (spaghetti bolognese) and 2 (curry and rice) male participants were shown an image of either a standard or a larger meal and indicated how much of the meal they intended to consume. In Study 3 male and female participants were served either a standard or a larger portion of ice cream for dessert, they indicated how much they intended to consume and then ate as much of the ice cream as they desired. Regardless of being shown standard or large portion sizes, in Studies 1 and 2 participants reported that they intended to eat the majority of the meal, equating to a large difference in intended energy consumption between portion size conditions (a 'pre-consumption portion size effect'). This finding was replicated in male participants in Study 3, although females intended to eat a smaller proportion of the larger portion of ice cream, compared to the standard portion. Both male and female participants tended to eat in accordance with their pre-meal intentions and a portion size effect on actual consumption was subsequently observed in males, but not in females. The portion size effect may be observed when measuring pre-meal intended consumption in males. Copyright © 2015. Published by Elsevier Ltd.

  2. Separation of both fibrous and globular proteins on the basis of molecular weight using high-performance size exclusion chromatography.

    Science.gov (United States)

    Barden, J A

    1983-11-01

    A high-performance size exclusion liquid chromatographic system has been used to separate proteins with different shapes solely on the basis of their molecular weights. After the effects of ionic and hydrophobic interactions with the stationary phase have been overcome, protein elution is normally governed by their effective size in solution. Conditions are described under which proteins, with isoelectric points within the normal operating pH range of the columns, are eluted independent of their Stokes' radii. Even fibrous proteins with axial ratios of 50 elute according to their known molecular weights over the range 2000-2,000,000.

  3. On the Da Vinci size effect in tensile strengths of nanowires: A molecular dynamics study

    Science.gov (United States)

    Zhao, Ziyu; Liu, Jinxing; Soh, Ai Kah

    2018-01-01

    In recent decades, size effects caused by grain size, strain gradient, typical defects etc., have been widely investigated. Nevertheless, the dependence of tensile strength on the specimen length, addressed by Da Vinci around 500 hundred years ago, has received rather limited attention, even though it is one unavoidable question to answer if people attempt to bring materials' amazing nano-scale strengths up to macro-level. Therefore, we make efforts to study tensile behaviors of copper nanowires with a common cross-section and various lengths by employing the molecular dynamics simulations. Surprisingly, a strong size effect of Da Vinci type indeed arises. We have shown the influences of lattice orientation, temperature and prescribed notch on such a Da Vinci size effect. Two different theoretical explanations are briefly proposed for a qualitative understanding. Finally, a simple scaling rule is summarized to cover the tendencies observed.

  4. Size-density relations in dark clouds: Non-LTE effects

    International Nuclear Information System (INIS)

    Maloney, P.

    1986-01-01

    One of the major goals of molecular astronomy has been to understand the physics and dynamics of dense interstellar clouds. Because the interpretation of observations of giant molecular clouds is complicated by their very complex structure and the dynamical effects of star formation, a number of studies have concentrated on dark clouds. Leung, Kutner and Mead (1982) (hereafter LKM) and Myers (1983), in studies of CO and NH 3 emission, concluded that dark clouds exhibit significant correlations between linewidth and cloud radius of the form delta v varies as R(0.5) and between mean density and radius of the form n varies as R(-1), as originally suggested by Larson (1981). This result suggests that these objects are in virial equilibrium. However, the mean densities inferred from the CO data of LKM are based on an local thermodynamic equilibrium (LTE) analysis of their 13CO data. At the very low mean densities inferred by LKM for the larger clouds in their samples, the assumption of LTE becomes very questionable. As most of the range in R in the density-size correlation comes from the clouds observed in CO, it seems worthwhile to examine how non-LTE effects will influence the derived densities. Microturbulent models of inhomogeneous clouds of varying central concentration with the linewidth-size and mean density-size relations found by Myers show sub-thermal excitation of the 13CO line in the larger clouds, with the result that LTE analysis considerbly underestimates the actual column density. A more general approach which doesn't require detailed modeling of the clouds is to consider whether the observed T/sub R/*(13CO)/T/sub R/*(12CO) ratios in the clouds studied by LKM are in the range where the LTE-derived optical depths be seriously in error due to sub-thermal excitation of the 13CO molecule

  5. Glenosphere size in reverse shoulder arthroplasty: is larger better for external rotation and abduction strength?

    Science.gov (United States)

    Müller, Andreas M; Born, Marian; Jung, Christian; Flury, Matthias; Kolling, Christoph; Schwyzer, Hans-Kaspar; Audigé, Laurent

    2018-01-01

    The role of glenosphere size in reverse shoulder arthroplasty (RSA) may be important in prosthetic stability, joint kinematics, rotator cuff tension and excursion, scapular impingement, humeral lateralization, deltoid wrap, and the occurrence of "notching." This study compared short- and midterm clinical and radiographic outcomes for 2 different glenosphere sizes of a single RSA type with respect to implant positioning, glenoid size, and morphology. This retrospective analysis included 68 RSA procedures that were prospectively documented in a local register during a 5-year postoperative period. Two glenosphere diameter sizes of 36 mm (n = 33) and 44 mm (n = 35) were used. Standard radiographs were made preoperatively (ie, baseline) and at 6, 12, 24, and 60 months after surgery. Range of motion, strength, the Constant-Murley score, and the Shoulder Pain and Disability Index were also assessed at all follow-up visits. The effect of glenosphere size on measured outcomes was adjusted for baseline values, patient gender, and humeral head diameter. No significant differences were found in the functional scores between treatment groups at all follow-up assessments. At the 12-month follow-up, patients with a 44-mm glenosphere had greater external rotation in adduction (mean difference, 12°; P = .001) and abduction strength (mean difference, 1.4 kg; P = .026) compared with those with the smaller implant. These differences remained at 60 months. Scapular notching was observed in 38% of all patients, without any relevant difference between the groups. An increase in glenosphere diameter leads to a clinically moderate but significant increase in external rotation in adduction and abduction strength at midterm follow-up. Copyright © 2017 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  6. THE MASS-SIZE RELATION FROM CLOUDS TO CORES. I. A NEW PROBE OF STRUCTURE IN MOLECULAR CLOUDS

    International Nuclear Information System (INIS)

    Kauffmann, J.; Shetty, R.; Goodman, A. A.; Pillai, T.; Myers, P. C.

    2010-01-01

    We use a new contour-based map analysis technique to measure the mass and size of molecular cloud fragments continuously over a wide range of spatial scales (0.05 ≤ r/pc ≤ 10), i.e., from the scale of dense cores to those of entire clouds. The present paper presents the method via a detailed exploration of the Perseus molecular cloud. Dust extinction and emission data are combined to yield reliable scale-dependent measurements of mass. This scale-independent analysis approach is useful for several reasons. First, it provides a more comprehensive characterization of a map (i.e., not biased toward a particular spatial scale). Such a lack of bias is extremely useful for the joint analysis of many data sets taken with different spatial resolution. This includes comparisons between different cloud complexes. Second, the multi-scale mass-size data constitute a unique resource to derive slopes of mass-size laws (via power-law fits). Such slopes provide singular constraints on large-scale density gradients in clouds.

  7. Larger aftershocks happen farther away: nonseparability of magnitude and spatial distributions of aftershocks

    Science.gov (United States)

    Van Der Elst, Nicholas; Shaw, Bruce E.

    2015-01-01

    Aftershocks may be driven by stress concentrations left by the main shock rupture or by elastic stress transfer to adjacent fault sections or strands. Aftershocks that occur within the initial rupture may be limited in size, because the scale of the stress concentrations should be smaller than the primary rupture itself. On the other hand, aftershocks that occur on adjacent fault segments outside the primary rupture may have no such size limitation. Here we use high-precision double-difference relocated earthquake catalogs to demonstrate that larger aftershocks occur farther away than smaller aftershocks, when measured from the centroid of early aftershock activity—a proxy for the initial rupture. Aftershocks as large as or larger than the initiating event nucleate almost exclusively in the outer regions of the aftershock zone. This observation is interpreted as a signature of elastic rebound in the earthquake catalog and can be used to improve forecasting of large aftershocks.

  8. On the Da Vinci size effect in tensile strengths of nanowires: A molecular dynamics study

    Directory of Open Access Journals (Sweden)

    Ziyu Zhao

    2018-01-01

    Full Text Available In recent decades, size effects caused by grain size, strain gradient, typical defects etc., have been widely investigated. Nevertheless, the dependence of tensile strength on the specimen length, addressed by Da Vinci around 500 hundred years ago, has received rather limited attention, even though it is one unavoidable question to answer if people attempt to bring materials’ amazing nano-scale strengths up to macro-level. Therefore, we make efforts to study tensile behaviors of copper nanowires with a common cross-section and various lengths by employing the molecular dynamics simulations. Surprisingly, a strong size effect of Da Vinci type indeed arises. We have shown the influences of lattice orientation, temperature and prescribed notch on such a Da Vinci size effect. Two different theoretical explanations are briefly proposed for a qualitative understanding. Finally, a simple scaling rule is summarized to cover the tendencies observed.

  9. More 'altruistic' punishment in larger societies.

    Science.gov (United States)

    Marlowe, Frank W; Berbesque, J Colette

    2008-03-07

    If individuals will cooperate with cooperators, and punish non-cooperators even at a cost to themselves, then this strong reciprocity could minimize the cheating that undermines cooperation. Based upon numerous economic experiments, some have proposed that human cooperation is explained by strong reciprocity and norm enforcement. Second-party punishment is when you punish someone who defected on you; third-party punishment is when you punish someone who defected on someone else. Third-party punishment is an effective way to enforce the norms of strong reciprocity and promote cooperation. Here we present new results that expand on a previous report from a large cross-cultural project. This project has already shown that there is considerable cross-cultural variation in punishment and cooperation. Here we test the hypothesis that population size (and complexity) predicts the level of third-party punishment. Our results show that people in larger, more complex societies engage in significantly more third-party punishment than people in small-scale societies.

  10. Oocyte size, egg index, and body lipid content in relation to body size in the solitary bee Megachile rotundata.

    Science.gov (United States)

    O'Neill, Kevin M; Delphia, Casey M; O'Neill, Ruth P

    2014-01-01

    Females of solitary, nest-provisioning bees have relatively low fecundity, but produce large eggs as part of their overall strategy of investing substantially in each offspring. In intraspecific comparisons of several species of solitary, nest-provisioning bees and wasps, the size of the mature eggs produced increases with female body size. We further examined oocyte size-body size correlations in the solitary bee Megachile rotundata (F.), an important crop pollinator. We hypothesized that larger females carry larger basal oocytes (i.e., those next in line to be oviposited) but that body size-oocyte size correlations would be absent soon after emergence, before their first eggs fully matured. Because egg production is likely affected by the quantity of stored lipids carried over from the bees' immature stages, we also tested the hypothesis that female body size is correlated with the body lipid content at adult emergence, the time during which oocyte growth accelerates. We found significant correlations of body size with oocyte size variables chosen to reflect: (1) the magnitude of the investment in the next egg to be laid (i.e., the length and volume of the basal oocyte) and (2) the longer term potential to produce mature oocytes (i.e., the summed lengths and volumes of the three largest oocytes in each female). Positive correlations existed throughout the nesting season, even during the first week following adult emergence. The ability to produce and carry larger oocytes may be linked to larger females starting the nesting season with greater lipid stores (which we document here) or to greater space within the abdomen of larger females. Compared to other species of solitary bees, M. rotundata appears to have (1) smaller oocytes than solitary nest-provisioning bees in general, (2) comparable oocyte sizes relative to congeners, and (3) larger oocytes than related brood parasitic megachilids.

  11. Molecular polymorphism of a cell surface proteoglycan: distinct structures on simple and stratified epithelia.

    Science.gov (United States)

    Sanderson, R D; Bernfield, M

    1988-12-01

    Epithelial cells are organized into either a single layer (simple epithelia) or multiple layers (stratified epithelia). Maintenance of these cellular organizations requires distinct adhesive mechanisms involving many cell surface molecules. One such molecule is a cell surface proteoglycan, named syndecan, that contains both heparan sulfate and chondroitin sulfate chains. This proteoglycan binds cells to fibrillar collagens and fibronectin and thus acts as a receptor for interstitial matrix. The proteoglycan is restricted to the basolateral surface of simple epithelial cells, but is located over the entire surface of stratified epithelial cells, even those surfaces not contacting matrix. We now show that the distinct localization in simple and stratified epithelia correlates with a distinct proteoglycan structure. The proteoglycan from simple epithelia (modal molecular size, 160 kDa) is larger than that from stratified epithelia (modal molecular size, 92 kDa), but their core proteins are identical in size and immunoreactivity. The proteoglycan from simple epithelia has more and larger heparan sulfate and chondroitin sulfate chains than the proteoglycan from stratified epithelia. Thus, the cell surface proteoglycan shows a tissue-specific structural polymorphism due to distinct posttranslational modifications. This polymorphism likely reflects distinct proteoglycan functions in simple and stratified epithelia, potentially meeting the different adhesive requirements of the cells in these different organizations.

  12. Base stock policies with degraded service to larger orders

    DEFF Research Database (Denmark)

    Du, Bisheng; Larsen, Christian

    We study an inventory system controlled by a base stock policy assuming a compound renewal demand process. We extend the base stock policy by incorporating rules for degrading the service of larger orders. Two specific rules are considered, denoted Postpone(q,t) and Split(q), respectively. The aim...... of using these rules is to achieve a given order fill rate of the regular orders (those of size less than or equal to the parameter q) having less inventory. We develop mathematical expressions for the performance measures order fill rate (of the regular orders) and average on-hand inventory level. Based...

  13. Does size matter? Study of performance of pseudo-ELISAs based on molecularly imprinted polymer nanoparticles prepared for analytes of different sizes.

    Science.gov (United States)

    Cáceres, C; Canfarotta, F; Chianella, I; Pereira, E; Moczko, E; Esen, C; Guerreiro, A; Piletska, E; Whitcombe, M J; Piletsky, S A

    2016-02-21

    The aim of this work is to evaluate whether the size of the analyte used as template for the synthesis of molecularly imprinted polymer nanoparticles (nanoMIPs) can affect their performance in pseudo-enzyme linked immunosorbent assays (pseudo-ELISAs). Successful demonstration of a nanoMIPs-based pseudo-ELISA for vancomycin (1449.3 g mol(-1)) was demonstrated earlier. In the present investigation, the following analytes were selected: horseradish peroxidase (HRP, 44 kDa), cytochrome C (Cyt C, 12 kDa) biotin (244.31 g mol(-1)) and melamine (126.12 g mol(-1)). NanoMIPs with a similar composition for all analytes were synthesised by persulfate-initiated polymerisation in water. In addition, core-shell nanoMIPs coated with polyethylene glycol (PEG) and imprinted for melamine were produced in organics and tested. The polymerisation of the nanoparticles was done using a solid-phase approach with the correspondent template immobilised on glass beads. The performance of the nanoMIPs used as replacement for antibodies in direct pseudo-ELISA (for the enzymes) and competitive pseudo-ELISA for the smaller analytes was investigated. For the competitive mode we rely on competition for the binding to the nanoparticles between free analyte and corresponding analyte-HRP conjugate. The results revealed that the best performances were obtained for nanoMIPs synthesised in aqueous media for the larger analytes. In addition, this approach was successful for biotin but completely failed for the smallest template melamine. This problem was solved using nanoMIP prepared by UV polymerisation in an organic media with a PEG shell. This study demonstrates that the preparation of nanoMIP by solid-phase approach can produce material with high affinity and potential to replace antibodies in ELISA tests for both large and small analytes. This makes this technology versatile and applicable to practically any target analyte and diagnostic field.

  14. A specialist toxicity database (TRACE) is more effective than its larger, commercially available counterparts

    NARCIS (Netherlands)

    Anderson, C.A.; Copestake, P.T.; Robinson, L.

    2000-01-01

    The retrieval precision and recall of a specialist bibliographic toxicity database (TRACE) and a range of widely available bibliographic databases used to identify toxicity papers were compared. The analysis indicated that the larger size and resources of the major bibliographic databases did not,

  15. Absorption spectroscopy of colored dissolved organic carbon in Georgia (USA rivers: the impact of molecular size distribution

    Directory of Open Access Journals (Sweden)

    Michelle McELVAINE

    2003-02-01

    Full Text Available Dissolved organic carbon (DOC was collected in six rivers that transect the coastal plain of Georgia in July 1999 and February 2000. DOC concentrations ranged from 4.9 to 40.7 g m-3 and from 7.1 to 40.5 g m-3, respectively. The absorption coefficient at 440 nm was highly correlated with DOC concentration, suggesting that the optical parameter may be utilized for rapid estimation of DOC in these waters. The isolated DOC was separated into fractions of operationally defined molecular size, using an ultrafiltration technique that yielded three fractions: 50 ("large" kilodalton. The smallest fraction was the most abundant (>50% in 4 rivers in July and in all rivers in February, and considerably more abundant than in previous years. The wavelength-dependent absorption of the total DOC and its fractions showed approximately uniform shape of a curve declining exponentially with the increase of wavelength. The average slope of logarithmically transformed curves was 0.0151 and 0.0159 nm-1, for the material collected in July and February, respectively and showed a dependence on DOC molecular size. In unfractionated DOC samples, the mass-specific light absorption determined at 440 nm was on average 0.33 m2 g-1 in July, and 0.26 m2 g-1 in February. The mass-specific absorption coefficient in all fractions ranged between 0.085 and 1.347 m2 g-1 in July and between 0.085 and 1.877 m2 g-1 in February, and was positively correlated with the molecular size of the measured samples. The results of the reported study clearly suggest that the specific absorption coefficient of the yellow substance is an outcome of the relative contribution of its different size fractions.

  16. Portion size: a qualitative study of consumers' attitudes toward point-of-purchase interventions aimed at portion size.

    Science.gov (United States)

    Vermeer, Willemijn M; Steenhuis, Ingrid H M; Seidell, Jacob C

    2010-02-01

    This qualitative study assessed consumers' opinions of food portion sizes and their attitudes toward portion-size interventions located in various point-of-purchase settings targeting overweight and obese people. Eight semi-structured focus group discussions were conducted with 49 participants. Constructs from the diffusion of innovations theory were included in the interview guide. Each focus group was recorded and transcribed verbatim. Data were coded and analyzed with Atlas.ti 5.2 using the framework approach. Results showed that many participants thought that portion sizes of various products have increased during the past decades and are larger than acceptable. The majority also indicated that value for money is important when purchasing and that large portion sizes offer more value for money than small portion sizes. Furthermore, many experienced difficulties with self-regulating the consumption of large portion sizes. Among the portion-size interventions that were discussed, participants had most positive attitudes toward a larger availability of portion sizes and pricing strategies, followed by serving-size labeling. In general, reducing package serving sizes as an intervention strategy to control food intake met resistance. The study concludes that consumers consider interventions consisting of a larger variety of available portion sizes, pricing strategies and serving-size labeling as most acceptable to implement.

  17. Poverty and household size

    NARCIS (Netherlands)

    Lanjouw, P.; Ravallion, M.

    1995-01-01

    The widely held view that larger families tend to be poorer in developing countries has influenced research and policy. The scope for size economies in consumption cautions against this view. The authors find that the correlation between poverty and size vanishes in Pakistan when the size elasticity

  18. Selective molecular sieving through porous graphene.

    Science.gov (United States)

    Koenig, Steven P; Wang, Luda; Pellegrino, John; Bunch, J Scott

    2012-11-01

    Membranes act as selective barriers and play an important role in processes such as cellular compartmentalization and industrial-scale chemical and gas purification. The ideal membrane should be as thin as possible to maximize flux, mechanically robust to prevent fracture, and have well-defined pore sizes to increase selectivity. Graphene is an excellent starting point for developing size-selective membranes because of its atomic thickness, high mechanical strength, relative inertness and impermeability to all standard gases. However, pores that can exclude larger molecules but allow smaller molecules to pass through would have to be introduced into the material. Here, we show that ultraviolet-induced oxidative etching can create pores in micrometre-sized graphene membranes, and the resulting membranes can be used as molecular sieves. A pressurized blister test and mechanical resonance are used to measure the transport of a range of gases (H(2), CO(2), Ar, N(2), CH(4) and SF(6)) through the pores. The experimentally measured leak rate, separation factors and Raman spectrum agree well with models based on effusion through a small number of ångstrom-sized pores.

  19. Influence of template/functional monomer/cross‐linking monomer ratio on particle size and binding properties of molecularly imprinted nanoparticles

    DEFF Research Database (Denmark)

    Yoshimatsu, Keiichi; Yamazaki, Tomohiko; Chronakis, Ioannis S.

    2012-01-01

    A series of molecularly imprinted polymer nanoparticles have been synthesized employing various template/functional monomer/crosslinking monomer ratio and characterized in detail to elucidate the correlation between the synthetic conditions used and the properties (e.g., particle size and templat...... tuning of particle size and binding properties are required to fit practical applications. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012...

  20. BODY SIZE AND HAREM SIZE IN MALE RED-WINGED BLACKBIRDS: MANIPULATING SELECTION WITH SEX-SPECIFIC FEEDERS.

    Science.gov (United States)

    Rohwer, Sievert; Langston, Nancy; Gori, Dave

    1996-10-01

    We experimentally manipulated the strength of selection in the field on red-winged blackbirds (Agelaius phoeniceus) to test hypotheses about contrasting selective forces that favor either large or small males in sexually size dimorphic birds. Selander (1972) argued that sexual selection favors larger males, while survival selection eventually stabilizes male size because larger males do not survive as well as smaller males during harsh winters. Searcy (1979a) proposed instead that sexual selection may be self limiting: male size might be stabilized not by overwinter mortality, but by breeding-season sexual selection that favors smaller males. Under conditions of energetic stress, smaller males should be able to display more and thus achieve higher reproductive success. Using feeders that provisioned males or females but not both, we produced conditions that mimicked the extremes of natural conditions. We found experimental support for the hypothesis that when food is abundant, sexual selection favors larger males. But even under conditions of severe energetic stress, smaller males did not gain larger harems, as the self-limiting hypothesis predicted. Larger males were more energetically stressed than smaller males, but in ways that affected their future reproductive output rather than their current reproductive performance. Stressed males that returned had smaller wings and tails than those that did not return; among returning stressed males, relative harem sizes were inversely related to wing and tail length. Thus, male body size may be stabilized not by survival costs during the non-breeding season, nor by energetic costs during the breeding season, but by costs of future reproduction that larger males pay for their increased breeding-season effort. © 1996 The Society for the Study of Evolution.

  1. Oocyte size, egg index, and body lipid content in relation to body size in the solitary bee Megachile rotundata

    Directory of Open Access Journals (Sweden)

    Kevin M. O’Neill

    2014-03-01

    Full Text Available Females of solitary, nest-provisioning bees have relatively low fecundity, but produce large eggs as part of their overall strategy of investing substantially in each offspring. In intraspecific comparisons of several species of solitary, nest-provisioning bees and wasps, the size of the mature eggs produced increases with female body size. We further examined oocyte size–body size correlations in the solitary bee Megachile rotundata (F., an important crop pollinator. We hypothesized that larger females carry larger basal oocytes (i.e., those next in line to be oviposited but that body size–oocyte size correlations would be absent soon after emergence, before their first eggs fully matured. Because egg production is likely affected by the quantity of stored lipids carried over from the bees’ immature stages, we also tested the hypothesis that female body size is correlated with the body lipid content at adult emergence, the time during which oocyte growth accelerates. We found significant correlations of body size with oocyte size variables chosen to reflect: (1 the magnitude of the investment in the next egg to be laid (i.e., the length and volume of the basal oocyte and (2 the longer term potential to produce mature oocytes (i.e., the summed lengths and volumes of the three largest oocytes in each female. Positive correlations existed throughout the nesting season, even during the first week following adult emergence. The ability to produce and carry larger oocytes may be linked to larger females starting the nesting season with greater lipid stores (which we document here or to greater space within the abdomen of larger females. Compared to other species of solitary bees, M. rotundata appears to have (1 smaller oocytes than solitary nest-provisioning bees in general, (2 comparable oocyte sizes relative to congeners, and (3 larger oocytes than related brood parasitic megachilids.

  2. The nearly neutral and selection theories of molecular evolution under the fisher geometrical framework: substitution rate, population size, and complexity.

    Science.gov (United States)

    Razeto-Barry, Pablo; Díaz, Javier; Vásquez, Rodrigo A

    2012-06-01

    The general theories of molecular evolution depend on relatively arbitrary assumptions about the relative distribution and rate of advantageous, deleterious, neutral, and nearly neutral mutations. The Fisher geometrical model (FGM) has been used to make distributions of mutations biologically interpretable. We explored an FGM-based molecular model to represent molecular evolutionary processes typically studied by nearly neutral and selection models, but in which distributions and relative rates of mutations with different selection coefficients are a consequence of biologically interpretable parameters, such as the average size of the phenotypic effect of mutations and the number of traits (complexity) of organisms. A variant of the FGM-based model that we called the static regime (SR) represents evolution as a nearly neutral process in which substitution rates are determined by a dynamic substitution process in which the population's phenotype remains around a suboptimum equilibrium fitness produced by a balance between slightly deleterious and slightly advantageous compensatory substitutions. As in previous nearly neutral models, the SR predicts a negative relationship between molecular evolutionary rate and population size; however, SR does not have the unrealistic properties of previous nearly neutral models such as the narrow window of selection strengths in which they work. In addition, the SR suggests that compensatory mutations cannot explain the high rate of fixations driven by positive selection currently found in DNA sequences, contrary to what has been previously suggested. We also developed a generalization of SR in which the optimum phenotype can change stochastically due to environmental or physiological shifts, which we called the variable regime (VR). VR models evolution as an interplay between adaptive processes and nearly neutral steady-state processes. When strong environmental fluctuations are incorporated, the process becomes a selection model

  3. Molecular clock in neutral protein evolution

    Directory of Open Access Journals (Sweden)

    Wilke Claus O

    2004-08-01

    Full Text Available Abstract Background A frequent observation in molecular evolution is that amino-acid substitution rates show an index of dispersion (that is, ratio of variance to mean substantially larger than one. This observation has been termed the overdispersed molecular clock. On the basis of in silico protein-evolution experiments, Bastolla and coworkers recently proposed an explanation for this observation: Proteins drift in neutral space, and can temporarily get trapped in regions of substantially reduced neutrality. In these regions, substitution rates are suppressed, which results in an overall substitution process that is not Poissonian. However, the simulation method of Bastolla et al. is representative only for cases in which the product of mutation rate μ and population size Ne is small. How the substitution process behaves when μNe is large is not known. Results Here, I study the behavior of the molecular clock in in silico protein evolution as a function of mutation rate and population size. I find that the index of dispersion decays with increasing μNe, and approaches 1 for large μNe . This observation can be explained with the selective pressure for mutational robustness, which is effective when μNe is large. This pressure keeps the population out of low-neutrality traps, and thus steadies the ticking of the molecular clock. Conclusions The molecular clock in neutral protein evolution can fall into two distinct regimes, a strongly overdispersed one for small μNe, and a mostly Poissonian one for large μNe. The former is relevant for the majority of organisms in the plant and animal kingdom, and the latter may be relevant for RNA viruses.

  4. Global warming may disproportionately affect larger adults in a predatory coral reef fish

    KAUST Repository

    Messmer, Vanessa

    2016-11-03

    Global warming is expected to reduce body sizes of ectothermic animals. Although the underlying mechanisms of size reductions remain poorly understood, effects appear stronger at latitudinal extremes (poles and tropics) and in aquatic rather than terrestrial systems. To shed light on this phenomenon, we examined the size dependence of critical thermal maxima (CTmax) and aerobic metabolism in a commercially important tropical reef fish, the leopard coral grouper (Plectropomus leopardus) following acclimation to current-day (28.5 °C) vs. projected end-of-century (33 °C) summer temperatures for the northern Great Barrier Reef (GBR). CTmax declined from 38.3 to 37.5 °C with increasing body mass in adult fish (0.45-2.82 kg), indicating that larger individuals are more thermally sensitive than smaller conspecifics. This may be explained by a restricted capacity for large fish to increase mass-specific maximum metabolic rate (MMR) at 33 °C compared with 28.5 °C. Indeed, temperature influenced the relationship between metabolism and body mass (0.02-2.38 kg), whereby the scaling exponent for MMR increased from 0.74 ± 0.02 at 28.5 °C to 0.79 ± 0.01 at 33 °C, and the corresponding exponents for standard metabolic rate (SMR) were 0.75 ± 0.04 and 0.80 ± 0.03. The increase in metabolic scaling exponents at higher temperatures suggests that energy budgets may be disproportionately impacted in larger fish and contribute to reduced maximum adult size. Such climate-induced reductions in body size would have important ramifications for fisheries productivity, but are also likely to have knock-on effects for trophodynamics and functioning of ecosystems.

  5. Global warming may disproportionately affect larger adults in a predatory coral reef fish

    KAUST Repository

    Messmer, Vanessa; Pratchett, Morgan S.; Hoey, Andrew S.; Tobin, Andrew J.; Coker, Darren James; Cooke, Steven J.; Clark, Timothy D.

    2016-01-01

    Global warming is expected to reduce body sizes of ectothermic animals. Although the underlying mechanisms of size reductions remain poorly understood, effects appear stronger at latitudinal extremes (poles and tropics) and in aquatic rather than terrestrial systems. To shed light on this phenomenon, we examined the size dependence of critical thermal maxima (CTmax) and aerobic metabolism in a commercially important tropical reef fish, the leopard coral grouper (Plectropomus leopardus) following acclimation to current-day (28.5 °C) vs. projected end-of-century (33 °C) summer temperatures for the northern Great Barrier Reef (GBR). CTmax declined from 38.3 to 37.5 °C with increasing body mass in adult fish (0.45-2.82 kg), indicating that larger individuals are more thermally sensitive than smaller conspecifics. This may be explained by a restricted capacity for large fish to increase mass-specific maximum metabolic rate (MMR) at 33 °C compared with 28.5 °C. Indeed, temperature influenced the relationship between metabolism and body mass (0.02-2.38 kg), whereby the scaling exponent for MMR increased from 0.74 ± 0.02 at 28.5 °C to 0.79 ± 0.01 at 33 °C, and the corresponding exponents for standard metabolic rate (SMR) were 0.75 ± 0.04 and 0.80 ± 0.03. The increase in metabolic scaling exponents at higher temperatures suggests that energy budgets may be disproportionately impacted in larger fish and contribute to reduced maximum adult size. Such climate-induced reductions in body size would have important ramifications for fisheries productivity, but are also likely to have knock-on effects for trophodynamics and functioning of ecosystems.

  6. Global warming may disproportionately affect larger adults in a predatory coral reef fish.

    Science.gov (United States)

    Messmer, Vanessa; Pratchett, Morgan S; Hoey, Andrew S; Tobin, Andrew J; Coker, Darren J; Cooke, Steven J; Clark, Timothy D

    2017-06-01

    Global warming is expected to reduce body sizes of ectothermic animals. Although the underlying mechanisms of size reductions remain poorly understood, effects appear stronger at latitudinal extremes (poles and tropics) and in aquatic rather than terrestrial systems. To shed light on this phenomenon, we examined the size dependence of critical thermal maxima (CTmax) and aerobic metabolism in a commercially important tropical reef fish, the leopard coral grouper (Plectropomus leopardus) following acclimation to current-day (28.5 °C) vs. projected end-of-century (33 °C) summer temperatures for the northern Great Barrier Reef (GBR). CTmax declined from 38.3 to 37.5 °C with increasing body mass in adult fish (0.45-2.82 kg), indicating that larger individuals are more thermally sensitive than smaller conspecifics. This may be explained by a restricted capacity for large fish to increase mass-specific maximum metabolic rate (MMR) at 33 °C compared with 28.5 °C. Indeed, temperature influenced the relationship between metabolism and body mass (0.02-2.38 kg), whereby the scaling exponent for MMR increased from 0.74 ± 0.02 at 28.5 °C to 0.79 ± 0.01 at 33 °C, and the corresponding exponents for standard metabolic rate (SMR) were 0.75 ± 0.04 and 0.80 ± 0.03. The increase in metabolic scaling exponents at higher temperatures suggests that energy budgets may be disproportionately impacted in larger fish and contribute to reduced maximum adult size. Such climate-induced reductions in body size would have important ramifications for fisheries productivity, but are also likely to have knock-on effects for trophodynamics and functioning of ecosystems. © 2016 John Wiley & Sons Ltd.

  7. The effects of size, shape, and surface composition on the diffusive behaviors of nanoparticles at/across water–oil interfaces via molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Wei; Jiao, Yang; Dai, Lenore L., E-mail: Lenore.Dai@asu.edu [Arizona State University, School of Engineering of Matter, Transport, and Energy (United States)

    2016-04-15

    We have employed molecular dynamics simulations to systematically investigate the effects of nanoparticles’ structural and chemical properties on their diffusive behaviors at/across the water–benzene interface. Four different nanoparticles were studied: modified hydrocarbon nanoparticles with a mean diameter of 1.2 nm (1.2HCPs), modified hydrocarbon nanoparticles with a mean diameter of 0.6 nm (0.6HCPs), single-walled carbon nanotubes (SWCNTs), and buckyballs. We found that the diffusion coefficients of 0.6 and 1.2HCP were larger than the corresponding values predicted using the Stokes–Einstein (SE) equation and attributed this deviation to the small particle size and the anisotropy of the interface system. In addition, the observed directional diffusive behaviors for various particles were well-correlated with the derivative of the potential of mean force (PMF), which might indicate an effective driving force for the particles along the direction perpendicular to the interface. We also found that nanoparticles with isotropic shape and uniform surface, e.g., buckyballs, tend to have smaller diffusion coefficients than those of nanoparticles with comparable dimensions but anisotropic shapes and non-uniform surface composition, e.g., SWCNT and 0.6HCP. One possible hypothesis for this behavior is that the “perfect” isotropic shape and uniform surface of buckyballs result in a better-defined “solvation shell” (i.e., a shell of solution molecules), which leads to a larger “effective radius” of the particle, and thus, a reduced diffusion coefficient.

  8. The prognostic role of tumor size in early breast cancer in the era of molecular biology.

    Directory of Open Access Journals (Sweden)

    Anaid Anna Kasangian

    Full Text Available The prognosis of early breast cancer (EBC depends on patient and tumor characteristics. The association between tumor size, the largest diameter in TNM staging, and prognosis is well recognized. According to TNM, tumors classified as T2, could have very different volumes; e.g. a tumor of 2.1 cm has a volume of 4500 mm3, while a tumor of 4.9 cm has a volume of 60.000 mm3 even belonging to the same class. The aim of the study is to establish if the prognostic role of tumor size, expressed as diameter and volume, has been overshadowed by other factors.The primary objective is to evaluate the association between tumor dimensions and overall survival (OS / disease free survival (DFS, in our institution from January 1st 2005 to September 30th 2013 in a surgical T1-T2 population. Volume was evaluated with the measurement of three half-diameters of the tumor (a, b and c, and calculated using the following formula: 4/3π x a x b x c.341 patients with T1-T2 EBC were included. 86.5% were treated with conservative surgery. 85.1% had a Luminal subtype, 9.1% were Triple negative and 7.4% were HER2 positive. Median volume was 942 mm3 (range 0.52-31.651.2. 44 patients (12.9% relapsed and 23 patients died. With a median follow-up of 6.5 years, the univariate analysis for DFS showed an association between age, tumor size, volume, histological grading and molecular subtype. The multivariate analysis confirmed the statistically significant association only for molecular subtype (p 0.005, with a worse prognosis for Triple negative and HER2 positive subtypes compared with Luminal (HR: 2.65; 95%CI: 1.34-5.22. Likewise for OS, an association was shown by the multivariate analysis solely for molecular subtype (HER2 and Triple negative vs. Luminal. HR: 2.83; 95% CI:1.46-5.49; p 0.002.In our study, the only parameter that strongly influences survival is molecular subtype. These findings encourage clinicians to choose adjuvant treatment not based on dimensional criteria

  9. The prognostic role of tumor size in early breast cancer in the era of molecular biology.

    Science.gov (United States)

    Kasangian, Anaid Anna; Gherardi, Giorgio; Biagioli, Elena; Torri, Valter; Moretti, Anna; Bernardin, Elena; Cordovana, Andrea; Farina, Gabriella; Bramati, Annalisa; Piva, Sheila; Dazzani, Maria Chiara; Paternò, Emanuela; La Verde, Nicla Maria

    2017-01-01

    The prognosis of early breast cancer (EBC) depends on patient and tumor characteristics. The association between tumor size, the largest diameter in TNM staging, and prognosis is well recognized. According to TNM, tumors classified as T2, could have very different volumes; e.g. a tumor of 2.1 cm has a volume of 4500 mm3, while a tumor of 4.9 cm has a volume of 60.000 mm3 even belonging to the same class. The aim of the study is to establish if the prognostic role of tumor size, expressed as diameter and volume, has been overshadowed by other factors. The primary objective is to evaluate the association between tumor dimensions and overall survival (OS) / disease free survival (DFS), in our institution from January 1st 2005 to September 30th 2013 in a surgical T1-T2 population. Volume was evaluated with the measurement of three half-diameters of the tumor (a, b and c), and calculated using the following formula: 4/3π x a x b x c. 341 patients with T1-T2 EBC were included. 86.5% were treated with conservative surgery. 85.1% had a Luminal subtype, 9.1% were Triple negative and 7.4% were HER2 positive. Median volume was 942 mm3 (range 0.52-31.651.2). 44 patients (12.9%) relapsed and 23 patients died. With a median follow-up of 6.5 years, the univariate analysis for DFS showed an association between age, tumor size, volume, histological grading and molecular subtype. The multivariate analysis confirmed the statistically significant association only for molecular subtype (p 0.005), with a worse prognosis for Triple negative and HER2 positive subtypes compared with Luminal (HR: 2.65; 95%CI: 1.34-5.22). Likewise for OS, an association was shown by the multivariate analysis solely for molecular subtype (HER2 and Triple negative vs. Luminal. HR: 2.83; 95% CI:1.46-5.49; p 0.002). In our study, the only parameter that strongly influences survival is molecular subtype. These findings encourage clinicians to choose adjuvant treatment not based on dimensional criteria but on

  10. Calibration of denaturing agarose gels for molecular weight estimation of DNA: size determination of the single-stranded genomes of parvoviruses

    Energy Technology Data Exchange (ETDEWEB)

    Snyder, C.E. (Oak Ridge National Lab., TN); Schmoyer, R.L.; Bates, R.C.; Mitra, S.

    1982-01-01

    Vertical slab gel electrophoresis of DNA with CH/sub 3/HgOH-containing agarose produces sharp bands whose mobilities are suitable for size estimation of single-stranded DNA containing 600 to 20,000 bases. The relationship of electrophoretic mobility to size of DNA over this range is a smooth, S-shaped function, and an empirical model was developed to express the relationship. The model involves terms in squared and reciprocal mobilities, and produced excellent fit of known standard markers to measured mobilities. It was used to estimate the sizes of six parvovirus DNAs: Kilham rat virus (KRV), H-1, LuIII, and minute virus of mice (MVM) DNAs had molecular weights of 1.66 to 1.70 x 10/sup 6/, while the molecular weight of bovine parvovirus (BPV) DNA was 1.84 x 10/sup 6/ and that of adenoassociated virus (AAV) DNA was 1.52 x 10/sup 6/.

  11. Measuring the molecular dimensions of wine tannins: comparison of small-angle X-ray scattering, gel-permeation chromatography and mean degree of polymerization.

    Science.gov (United States)

    McRae, Jacqui M; Kirby, Nigel; Mertens, Haydyn D T; Kassara, Stella; Smith, Paul A

    2014-07-23

    The molecular size of wine tannins can influence astringency, and yet it has been unclear as to whether the standard methods for determining average tannin molecular weight (MW), including gel-permeation chromatography (GPC) and depolymerization reactions, are actually related to the size of the tannin in wine-like conditions. Small-angle X-ray scattering (SAXS) was therefore used to determine the molecular sizes and corresponding MWs of wine tannin samples from 3 and 7 year old Cabernet Sauvignon wine in a variety of wine-like matrixes: 5-15% and 100% ethanol; 0-200 mM NaCl and pH 3.0-4.0, and compared to those measured using the standard methods. The SAXS results indicated that the tannin samples from the older wine were larger than those of the younger wine and that wine composition did not greatly impact on tannin molecular size. The average tannin MWs as determined by GPC correlated strongly with the SAXS results, suggesting that this method does give a good indication of tannin molecular size in wine-like conditions. The MW as determined from the depolymerization reactions did not correlate as strongly with the SAXS results. To our knowledge, SAXS measurements have not previously been attempted for wine tannins.

  12. Size-density relations in dark clouds: Non-LTE effects

    Science.gov (United States)

    Maloney, P.

    1986-01-01

    One of the major goals of molecular astronomy has been to understand the physics and dynamics of dense interstellar clouds. Because the interpretation of observations of giant molecular clouds is complicated by their very complex structure and the dynamical effects of star formation, a number of studies have concentrated on dark clouds. Leung, Kutner and Mead (1982) (hereafter LKM) and Myers (1983), in studies of CO and NH3 emission, concluded that dark clouds exhibit significant correlations between linewidth and cloud radius of the form delta v varies as R(0.5) and between mean density and radius of the form n varies as R(-1), as originally suggested by Larson (1981). This result suggests that these objects are in virial equilibrium. However, the mean densities inferred from the CO data of LKM are based on an local thermodynamic equilibrium (LTE) analysis of their 13CO data. At the very low mean densities inferred by LKM for the larger clouds in their samples, the assumption of LTE becomes very questionable. As most of the range in R in the density-size correlation comes from the clouds observed in CO, it seems worthwhile to examine how non-LTE effects will influence the derived densities. One way to assess the validity of LTE-derived densities is to construct cloud models and then to interpret them in the same way as the observed data. Microturbulent models of inhomogeneous clouds of varying central concentration with the linewidth-size and mean density-size relations found by Myers show sub-thermal excitation of the 13CO line in the larger clouds, with the result that LTE analysis considerbly underestimates the actual column density. A more general approach which doesn't require detailed modeling of the clouds is to consider whether the observed T sub R*(13CO)/T sub R*(12CO) ratios in the clouds studied by LKM are in the range where the LTE-derived optical depths (and hence column densities) can be seriously in error due to sub-thermal excitation of the 13CO

  13. More ‘altruistic’ punishment in larger societies

    Science.gov (United States)

    Marlowe, Frank W; Berbesque, J. Colette; Barr, Abigail; Barrett, Clark; Bolyanatz, Alexander; Cardenas, Juan Camilo; Ensminger, Jean; Gurven, Michael; Gwako, Edwins; Henrich, Joseph; Henrich, Natalie; Lesorogol, Carolyn; McElreath, Richard; Tracer, David

    2007-01-01

    If individuals will cooperate with cooperators, and punish non-cooperators even at a cost to themselves, then this strong reciprocity could minimize the cheating that undermines cooperation. Based upon numerous economic experiments, some have proposed that human cooperation is explained by strong reciprocity and norm enforcement. Second-party punishment is when you punish someone who defected on you; third-party punishment is when you punish someone who defected on someone else. Third-party punishment is an effective way to enforce the norms of strong reciprocity and promote cooperation. Here we present new results that expand on a previous report from a large cross-cultural project. This project has already shown that there is considerable cross-cultural variation in punishment and cooperation. Here we test the hypothesis that population size (and complexity) predicts the level of third-party punishment. Our results show that people in larger, more complex societies engage in significantly more third-party punishment than people in small-scale societies. PMID:18089534

  14. A general model for the scaling of offspring size and adult size.

    Science.gov (United States)

    Falster, Daniel S; Moles, Angela T; Westoby, Mark

    2008-09-01

    Understanding evolutionary coordination among different life-history traits is a key challenge for ecology and evolution. Here we develop a general quantitative model predicting how offspring size should scale with adult size by combining a simple model for life-history evolution with a frequency-dependent survivorship model. The key innovation is that larger offspring are afforded three different advantages during ontogeny: higher survivorship per time, a shortened juvenile phase, and advantage during size-competitive growth. In this model, it turns out that size-asymmetric advantage during competition is the factor driving evolution toward larger offspring sizes. For simplified and limiting cases, the model is shown to produce the same predictions as the previously existing theory on which it is founded. The explicit treatment of different survival advantages has biologically important new effects, mainly through an interaction between total maternal investment in reproduction and the duration of competitive growth. This goes on to explain alternative allometries between log offspring size and log adult size, as observed in mammals (slope = 0.95) and plants (slope = 0.54). Further, it suggests how these differences relate quantitatively to specific biological processes during recruitment. In these ways, the model generalizes across previous theory and provides explanations for some differences between major taxa.

  15. Degree of Response to Homeopathic Potencies Correlates with Dipole Moment Size in Molecular Detectors: Implications for Understanding the Fundamental Nature of Serially Diluted and Succussed Solutions.

    Science.gov (United States)

    Cartwright, Steven J

    2018-02-01

     The use of solvatochromic dyes to investigate homeopathic potencies holds out the promise of understanding the nature of serially succussed and diluted solutions at a fundamental physicochemical level. Recent studies have shown that a range of different dyes interact with potencies and, moreover, the nature of the interaction is beginning to allow certain specific characteristics of potencies to be delineated.  The study reported in this article takes previous investigations further and aims to understand more about the nature of the interaction between potencies and solvatochromic dyes. To this end, the UV-visible spectra of a wide range of potential detectors of potencies have been examined using methodologies previously described.  Results presented demonstrate that solvatochromic dyes are a sub-group of a larger class of compounds capable of demonstrating interactions with potencies. In particular, amino acids containing an aromatic bridge also show marked optical changes in the presence of potencies. Several specific features of molecular detectors can now be shown to be necessary for significant interactions with homeopathic potencies. These include systems with a large dipole moment, electron delocalisation, polarizability and molecular rigidity.  Analysis of the optical changes occurring on interaction with potencies suggests that in all cases potencies increase the polarity of molecular detectors to a degree that correlates with the size of the compound's permanent or ground dipole moment. These results can be explained by inferring that potencies themselves have polarity. Possible candidates for the identity of potencies, based on these and previously reported results, are discussed. The Faculty of Homeopathy.

  16. The effect of solvent upon molecularly thin rotaxane film formation

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, Alan A. [Nanoscale Function Group, Centre for Research on Adaptive Nanostructures and Nanodevices, University of Dublin, Trinity College, Dublin 2 (Ireland)]. E-mail: farrelaa@tcd.ie; Kay, Euan R. [School of Chemistry, University of Edinburgh, The King' s Buildings, West Mains Road, Edinburgh EH9 3 JJ (United Kingdom); Bottari, Giovanni [School of Chemistry, University of Edinburgh, The King' s Buildings, West Mains Road, Edinburgh EH9 3 JJ (United Kingdom); Leigh, David A. [School of Chemistry, University of Edinburgh, The King' s Buildings, West Mains Road, Edinburgh EH9 3 JJ (United Kingdom); Jarvis, Suzanne P. [Nanoscale Function Group, Centre for Research on Adaptive Nanostructures and Nanodevices, University of Dublin, Trinity College, Dublin 2 (Ireland)

    2007-05-15

    We have investigated variations in molecularly thin rotaxane films deposited by solvent evaporation, using atomic force microscopy (AFM). Small changes in rotaxane structure result in significant differences in film morphology. The addition of exo-pyridyl moietes to the rotaxane macrocycle results in uniform domains having orientations corresponding to the underlying substrate lattice, while a larger, less symmetric molecule results in a greater lattice mismatch and smaller domain sizes. We have measured differences in film heights both as a function of the solvent of deposition and as a function of surface coverage of rotaxanes. Based on these observations we describe how the use of solvents with higher hydrogen-bond basicity results in films which are more likely to favour sub-molecular motion.

  17. Body size and predatory performance in wolves: is bigger better?

    Science.gov (United States)

    MacNulty, Daniel R; Smith, Douglas W; Mech, L David; Eberly, Lynn E

    2009-05-01

    1. Large body size hinders locomotor performance in ways that may lead to trade-offs in predator foraging ability that limit the net predatory benefit of larger size. For example, size-related improvements in handling prey may come at the expense of pursuing prey and thus negate any enhancement in overall predatory performance due to increasing size. 2. This hypothesis was tested with longitudinal data from repeated observations of 94 individually known wolves (Canis lupus) hunting elk (Cervus elaphus) in Yellowstone National Park, USA. Wolf size was estimated from an individually based sex-specific growth model derived from body mass measurements of 304 wolves. 3. Larger size granted individual wolves a net predatory advantage despite substantial variation in its effect on the performance of different predatory tasks; larger size improved performance of a strength-related task (grappling and subduing elk) but failed to improve performance of a locomotor-related task (selecting an elk from a group) for wolves > 39 kg. 4. Sexual dimorphism in wolf size also explained why males outperformed females in each of the three tasks considered (attacking, selecting, and killing). 5. These findings support the generalization that bigger predators are overall better hunters, but they also indicate that increasing size ultimately limits elements of predatory behaviour that require superior locomotor performance. We argue that this could potentially narrow the dietary niche of larger carnivores as well as limit the evolution of larger size if prey are substantially more difficult to pursue than to handle.

  18. Molecular size estimation of plasma membrane β-glucan synthase from red beet root

    International Nuclear Information System (INIS)

    Sloan, M.E.; Eiberger, L.L.; Wasserman, B.P.

    1986-01-01

    Cellulose and cell wall β-D-glucans in higher plants are thought to be synthesized by the plasma membrane enzyme, β-glucan synthase. This enzyme has never been purified to homogeneity, hence its subunit composition is unknown. Partial purification of red beet root glucan synthase by glycerol density gradient centrifugation followed by SDS-PAGE yielded a highly enriched subunit of 68 kDa. Radiation inactivation of plasma membranes gave a molecular size the 450 kDa for the holoenzyme complex. This suggests that glucan synthase consists of 6 to 7 subunits and confirms electron microscope studies showing that glucan synthases exist as multi-subunit complexes embedded within the membrane

  19. Molecularly imprinted macroporous monoliths for solid-phase extraction: Effect of pore size and column length on recognition properties.

    Science.gov (United States)

    Vlakh, E G; Stepanova, M A; Korneeva, Yu M; Tennikova, T B

    2016-09-01

    The series of macroporous monolithic molecularly imprinted monoliths differed by pore size, column length (volume) and amount of template used for imprinting was synthesized using methacrylic acid and glycerol dimethacrylate as co-monomers and antibiotic ciprofloxacin as a template. The prepared monoliths were characterized regarding to their permeability, pore size, porosity, and resistance to the flow of a mobile phase. The surface morphology was also analyzed. The slight dependence of imprinting factor on flow rate, as well as its independence on pore size of macroporous molecularly imprinted monolithic media was observed. The column obtained at different conditions exhibited different affinity of ciprofloxacin to the imprinted sites that was characterized with Kdiss values in the range of 10(-5)-10(-4)M. The solid-phase extraction of ciprofloxacin from such biological liquids as human blood serum, human urine and cow milk serum was performed using the developed monolithic columns. In all cases, the extraction was found to be 95.0-98.6%. Additionally, the comparison of extraction of three fluoroqinolone analogues, e.g. ciprofloxacin, levofloxacin and moxifloxacin, from human blood plasma was carried out. Contrary to ciprofloxacin extracted with more than 95%, this parameter did not exceed 40% for its analogues. Copyright © 2016 Elsevier B.V. All rights reserved.

  20. Size effect on local magnetic moments in ferrimagnetic molecular complexes: an XMCD investigation

    International Nuclear Information System (INIS)

    Champion, G.; Villain, F.; Cartier dit Moulin, C.; Arrio, M.-A.; Sainctavit, P.; Zacchigna, M.; Zangrando, M.; Finazzi, M.; Parmigiani, F.; Mathoniere, C.

    2003-01-01

    Molecular chemistry allows to synthesize new magnetic systems with controlled properties such as size, magnetization or anisotropy. The theoretical study of the magnetic properties of small molecules (from 2 to 10 metallic cations per molecule) predicts that the magnetization at saturation of each ion does not reach the expected value for uncoupled ions when the magnetic interaction is antiferromagnetic. The quantum origin of this effect is due to the linear combination of several spin states building the wave function of the ground state and clusters of finite size and of finite spin value exhibit this property. When single crystals are available, spin densities on each atom can be experimentally given by polarized neutron diffraction (PND) experiments. In the case of bimetallic MnCu powdered samples, we will show that x-ray magnetic circular dichroism (XMCD) spectroscopy can be used to follow the evolution of the spin distribution on the Mn II and Cu II sites when passing from a dinuclear MnCu unit to a one dimensional (MnCu) n compound. (author)

  1. Size Evolution and Stochastic Models: Explaining Ostracod Size through Probabilistic Distributions

    Science.gov (United States)

    Krawczyk, M.; Decker, S.; Heim, N. A.; Payne, J.

    2014-12-01

    The biovolume of animals has functioned as an important benchmark for measuring evolution throughout geologic time. In our project, we examined the observed average body size of ostracods over time in order to understand the mechanism of size evolution in these marine organisms. The body size of ostracods has varied since the beginning of the Ordovician, where the first true ostracods appeared. We created a stochastic branching model to create possible evolutionary trees of ostracod size. Using stratigraphic ranges for ostracods compiled from over 750 genera in the Treatise on Invertebrate Paleontology, we calculated overall speciation and extinction rates for our model. At each timestep in our model, new lineages can evolve or existing lineages can become extinct. Newly evolved lineages are assigned sizes based on their parent genera. We parameterized our model to generate neutral and directional changes in ostracod size to compare with the observed data. New sizes were chosen via a normal distribution, and the neutral model selected new sizes differentials centered on zero, allowing for an equal chance of larger or smaller ostracods at each speciation. Conversely, the directional model centered the distribution on a negative value, giving a larger chance of smaller ostracods. Our data strongly suggests that the overall direction of ostracod evolution has been following a model that directionally pushes mean ostracod size down, shying away from a neutral model. Our model was able to match the magnitude of size decrease. Our models had a constant linear decrease while the actual data had a much more rapid initial rate followed by a constant size. The nuance of the observed trends ultimately suggests a more complex method of size evolution. In conclusion, probabilistic methods can provide valuable insight into possible evolutionary mechanisms determining size evolution in ostracods.

  2. Modelling the effect of size-asymmetric competition on size inequality

    DEFF Research Database (Denmark)

    Rasmussen, Camilla Ruø; Weiner, Jacob

    2017-01-01

    Abstract The concept of size asymmetry in resource competition among plants, in which larger individuals obtain a disproportionate share of contested resources, appears to be very straightforward, but the effects of size asymmetry on growth and size variation among individuals have proved...... to be controversial. It has often been assumed that competition among individual plants in a population has to be size-asymmetric to result in higher size inequality than in the absence of competition, but here we question this inference. Using very simple, individual-based models, we investigate how size symmetry...... of competition affects the development in size inequality between two competing plants and show that increased size inequality due to competition is not always strong evidence for size-asymmetric competition. Even absolute symmetric competition, in which all plants receive the same amount of resources...

  3. Class size versus class composition

    DEFF Research Database (Denmark)

    Jones, Sam

    Raising schooling quality in low-income countries is a pressing challenge. Substantial research has considered the impact of cutting class sizes on skills acquisition. Considerably less attention has been given to the extent to which peer effects, which refer to class composition, also may affect...... bias from omitted variables, the preferred IV results indicate considerable negative effects due to larger class sizes and larger numbers of overage-for-grade peers. The latter, driven by the highly prevalent practices of grade repetition and academic redshirting, should be considered an important...

  4. The body size of the oil-collecting bee Tetrapedia diversipes (Apidae)

    OpenAIRE

    Pinto da Silva,Carlos; Silva,Adriana; Duran Cordeiro,Guaraci; Alves dos Santos ,Isabel

    2015-01-01

    The body size of bees can affect their fitness in many ways. There is an indirect relationship between the size of the mother and the size of her progeny. This is so because large mothers use larger nests and brood cells and have higher foraging capacity than small mothers, and consequently large mothers supply a larger amount of food to their larvae, which grow larger. We analyzed the relationship between body size of individual oil-collecting bees of the species Tetrapedia diversipes and th...

  5. Effect of gamma-irradiation on rice seed DNA. Pt. 1. Yield and molecular size of DNA extracted from irradiated rice seeds

    International Nuclear Information System (INIS)

    Kawamura, Yoko; Konishi, Akihiro; Yamada, Takashi; Saito, Yukio

    1995-01-01

    The effect of gamma-irradiation on the DNA of hulled rice seeds was investigated. The cetyltrimethylammonium bromide (CTAB) method was preferred for the extraction of DNA from rice seeds because of its high quality and good yield. The yield of DNA that was determined by gel electrophoresis, decreased as the irradiation dose increased from 1 kGy. DNA extracted from rice seeds irradiated with a 30 kGy dose showed a molecular size of less than 20 kb, while that from unirradiated rice showed more than 100 kb in electrophoretic profiles. It can be assumed that the decrease in yield was mainly induced by the crosslinking between protein and DNA, and the reduction in molecular size was induced by double-strand breaks. (J.P.N.)

  6. Body size and predatory performance in wolves: Is bigger better?

    Science.gov (United States)

    MacNulty, D.R.; Smith, D.W.; Mech, L.D.; Eberly, L.E.

    2009-01-01

    Large body size hinders locomotor performance in ways that may lead to trade-offs in predator foraging ability that limit the net predatory benefit of larger size. For example, size-related improvements in handling prey may come at the expense of pursuing prey and thus negate any enhancement in overall predatory performance due to increasing size. 2. This hypothesis was tested with longitudinal data from repeated observations of 94 individually known wolves (Canis lupus) hunting elk (Cervus elaphus) in Yellowstone National Park, USA. Wolf size was estimated from an individually based sex-specific growth model derived from body mass measurements of 304 wolves. 3. Larger size granted individual wolves a net predatory advantage despite substantial variation in its effect on the performance of different predatory tasks; larger size improved performance of a strength-related task (grappling and subduing elk) but failed to improve performance of a locomotor-related task (selecting an elk from a group) for wolves > 39 kg. 4. Sexual dimorphism in wolf size also explained why males outperformed females in each of the three tasks considered (attacking, selecting, and killing). 5. These findings support the generalization that bigger predators are overall better hunters, but they also indicate that increasing size ultimately limits elements of predatory behaviour that require superior locomotor performance. We argue that this could potentially narrow the dietary niche of larger carnivores as well as limit the evolution of larger size if prey are substantially more difficult to pursue than to handle. ?? 2009 British Ecological Society.

  7. Stereotactic Radiosurgery with Neoadjuvant Embolization of Larger Arteriovenous Malformations: An Institutional Experience

    Directory of Open Access Journals (Sweden)

    Richard Dalyai

    2014-01-01

    Full Text Available Objective. This study investigates the safety and efficacy of a multimodality approach combining staged endovascular embolizations with subsequent SRS for the management of larger AVMs. Methods. Ninety-five patients with larger AVMs were treated with staged endovascular embolization followed by SRS between 1996 and 2011. Results. The median volume of AVM in this series was 28 cm3 and 47 patients (48% were Spetzler-Martin grade IV or V. Twenty-seven patients initially presented with hemorrhage. Sixty-one patients underwent multiple embolizations while a single SRS session was performed in 64 patients. The median follow-up after SRS session was 32 months (range 9–136 months. Overall procedural complications occurred in 14 patients. There were 13 minor neurologic complications and 1 major complication (due to embolization while four patients had posttreatment hemorrhage. Thirty-eight patients (40% were cured radiographically. The postradiosurgery actuarial rate of obliteration was 45% at 5 years, 56% at 7 years, and 63% at 10 years. In multivariate analysis, larger AVM size, deep venous drainage, and the increasing number of embolization/SRS sessions were negative predictors of obliteration. The number of embolizations correlated positively with the number of stereotactic radiosurgeries (P<0.005. Conclusions. Multimodality endovascular and radiosurgical approach is an efficacious treatment strategy for large AVM.

  8. Influence of grain size on the mechanical properties of nano-crystalline copper; insights from molecular dynamics simulation

    Science.gov (United States)

    Rida, A.; Makke, A.; Rouhaud, E.; Micoulaut, M.

    2017-10-01

    We use molecular dynamics simulations to study the mechanical properties of a columnar nanocrystalline copper with a mean grain size between 8.91 nm and 24 nm. The used samples were generated by using a melting cooling method. These samples were submitted to uniaxial tensile test. The results reveal the presence of a critical mean grain size between 16 and 20 nm, where there is an inversion in the conventional Hall-Petch tendency. This inversion is illustrated by the increase of flow stress with the increase of the mean grain size. This transition is caused by shifting of the deformation mechanism from dislocations to a combination of grain boundaries sliding and dislocations. Moreover, the effect of temperature on the mechanical properties of nanocrystalline copper has been investigated. The results show a decrease of the flow stress and Young's modulus when the temperature increases.

  9. Mammal extinctions, body size, and paleotemperature.

    Science.gov (United States)

    Bown, T M; Holroyd, P A; Rose, K D

    1994-10-25

    There is a general inverse relationship between the natural logarithm of tooth area (a body size indicator) of some fossil mammals and paleotemperature during approximately 2.9 million years of the early Eocene in the Bighorn Basin of northwest Wyoming. When mean temperatures became warmer, tooth areas tended to become smaller. During colder times, larger species predominated; these generally became larger or remained the same size. Paleotemperature trends also markedly affected patterns of local (and, perhaps, regional) extinction and immigration. New species appeared as immigrants during or near the hottest (smaller forms) and coldest (larger forms) intervals. Paleotemperature trend reversals commonly resulted in the ultimate extinction of both small forms (during cooling intervals) and larger forms (during warming intervals). These immigrations and extinctions mark faunal turnovers that were also modulated by sharp increases in sediment accumulation rate.

  10. Ectopically expressing MdPIP1;3, an aquaporin gene, increased fruit size and enhanced drought tolerance of transgenic tomatoes.

    Science.gov (United States)

    Wang, Lin; Li, Qing-Tian; Lei, Qiong; Feng, Chao; Zheng, Xiaodong; Zhou, Fangfang; Li, Lingzi; Liu, Xuan; Wang, Zhi; Kong, Jin

    2017-12-19

    Water deficit severely reduces apple growth and production, is detrimental to fruit quality and size. This problem is exacerbated as global warming is implicated in producing more severe drought stress. Thus water-efficiency has becomes the major target for apple breeding. A desired apple tree can absorb and transport water efficiently, which not only confers improved drought tolerance, but also guarantees fruit size for higher income returns. Aquaporins, as water channels, control water transportation across membranes and can regulate water flow by changing their amount and activity. The exploration of molecular mechanism of water efficiency and the gene wealth will pave a way for molecular breeding of drought tolerant apple tree. In the current study, we screened out a drought inducible aquaporin gene MdPIP1;3, which specifically enhanced its expression during fruit expansion in 'Fuji' apple (Malus domestica Borkh. cv. Red Fuji). It localized on plasma membranes and belonged to PIP1 subfamily. The tolerance to drought stress enhanced in transgenic tomato plants ectopically expressing MdPIP1;3, showing that the rate of losing water in isolated transgenic leaves was slower than wild type, and stomata of transgenic plants closed sensitively to respond to drought compared with wild type. Besides, length and diameter of transgenic tomato fruits increased faster than wild type, and in final, fruit sizes and fresh weights of transgenic tomatoes were bigger than wild type. Specially, in cell levels, fruit cell size from transgenic tomatoes was larger than wild type, showing that cell number per mm 2 in transgenic fruits was less than wild type. Altogether, ectopically expressing MdPIP1;3 enhanced drought tolerance of transgenic tomatoes partially via reduced water loss controlled by stomata closure in leaves. In addition, the transgenic tomato fruits are larger and heavier with larger cells via more efficient water transportation across membranes. Our research will

  11. Molecular dynamics simulation of cyclodextrin aggregation and extraction of Anthracene from non-aqueous liquid phase

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Xinzhe [Shenzhen Key Laboratory for Coastal Ocean Dynamic and Environment, Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); School of Environment, Tsinghua University, Beijing 100084 (China); Wu, Guozhong [Shenzhen Key Laboratory for Coastal Ocean Dynamic and Environment, Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China); Chen, Daoyi, E-mail: chen.daoyi@sz.tsinghua.edu.cn [Shenzhen Key Laboratory for Coastal Ocean Dynamic and Environment, Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China)

    2016-12-15

    Cyclodextrin (CD) extraction is widely used for the remediation of polycyclic aromatic hydrocarbons (PAH) pollution, but it remains unclear about the influence of CD aggregation on the PAH transport from non-aqueous liquid phase to water. The atomistic adsorption and complexation of PAHs (32 anthracenes) by CD aggregates (48 β-cyclodextrins) were studied by molecular dynamics simulations at hundreds of nanoseconds time scale. Results indicated that high temperature promoted the βCD aggregation in bulk oil, which was not found in bulk water. Nevertheless, the fractions of anthracenes entrapped inside the βCDs cavity in both scenarios were significantly increased when temperature increased from 298 to 328 K. Free energy calculation for the sub-steps of CD extraction demonstrated that the anthracenes could be extracted when the βCDs arrived at the water-oil interface or after the βCDs entered the bulk oil. The former was kinetic-controlled while the latter was thermodynamic-limited process. Results also highlighted the formation of porous structures by CD aggregates in water, which was able to sequestrate PAH clusters with the size obviously larger than the cavity diameter of individual CD. This provided an opportunity for the extraction of recalcitrant PAHs with molecular size larger than anthracenes by cyclodextrins.

  12. Single Cell Analysis Linking Ribosomal (r)DNA and rRNA Copy Numbers to Cell Size and Growth Rate Provides Insights into Molecular Protistan Ecology.

    Science.gov (United States)

    Fu, Rao; Gong, Jun

    2017-11-01

    Ribosomal (r)RNA and rDNA have been golden molecular markers in microbial ecology. However, it remains poorly understood how ribotype copy number (CN)-based characteristics are linked with diversity, abundance, and activity of protist populations and communities observed at organismal levels. Here, we applied a single-cell approach to quantify ribotype CNs in two ciliate species reared at different temperatures. We found that in actively growing cells, the per-cell rDNA and rRNA CNs scaled with cell volume (CV) to 0.44 and 0.58 powers, respectively. The modeled rDNA and rRNA concentrations thus appear to be much higher in smaller than in larger cells. The observed rRNA:rDNA ratio scaled with CV 0.14 . The maximum growth rate could be well predicted by a combination of per-cell ribotype CN and temperature. Our empirical data and modeling on single-cell ribotype scaling are in agreement with both the metabolic theory of ecology and the growth rate hypothesis, providing a quantitative framework for linking cellular rDNA and rRNA CNs with body size, growth (activity), and biomass stoichiometry. This study also demonstrates that the expression rate of rRNA genes is constrained by cell size, and favors biomass rather than abundance-based interpretation of quantitative ribotype data in population and community ecology of protists. © 2017 The Authors. Journal of Eukaryotic Microbiology published by Wiley Periodicals, Inc. on behalf of International Society of Protistologists.

  13. Wetting kinetics of water nano-droplet containing non-surfactant nanoparticles: A molecular dynamics study

    International Nuclear Information System (INIS)

    Lu, Gui; Hu, Han; Sun, Ying; Duan, Yuanyuan

    2013-01-01

    In this Letter, dynamic wetting of water nano-droplets containing non-surfactant gold nanoparticles on a gold substrate is examined via molecular dynamics simulations. The results show that the addition of non-surfactant nanoparticles hinders the nano-second droplet wetting process, attributed to the increases in both surface tension of the nanofluid and friction between nanofluid and substrate. The droplet wetting kinetics decreases with increasing nanoparticle loading and water-particle interaction energy. The observed wetting suppression and the absence of nanoparticle ordering near the contact line of nano-sized droplets differ from the wetting behaviors reported from nanofluid droplets of micron size or larger

  14. Determination of the Molecular Weight of Low-Molecular-Weight Heparins by Using High-Pressure Size Exclusion Chromatography on Line with a Triple Detector Array and Conventional Methods

    Directory of Open Access Journals (Sweden)

    Antonella Bisio

    2015-03-01

    Full Text Available The evaluation of weight average molecular weight (Mw and molecular weight distribution represents one of the most controversial aspects concerning the characterization of low molecular weight heparins (LMWHs. As the most commonly used method for the measurement of such parameters is high performance size exclusion chromatography (HP-SEC, the soundness of results mainly depends on the appropriate calibration of the chromatographic columns used. With the aim of meeting the requirement of proper Mw standards for LMWHs, in the present work the determination of molecular weight parameters (Mw and Mn by HP-SEC combined with a triple detector array (TDA was performed. The HP-SEC/TDA technique permits the evaluation of polymeric samples by exploiting the combined and simultaneous action of three on-line detectors: light scattering detectors (LALLS/RALLS; refractometer and viscometer. Three commercial LMWH samples, enoxaparin, tinzaparin and dalteparin, a γ-ray depolymerized heparin (γ-Hep and its chromatographic fractions, and a synthetic pentasaccharide were analysed by HP-SEC/TDA. The same samples were analysed also with a conventional HP-SEC method employing refractive index (RI and UV detectors and two different chromatographic column set, silica gel and polymeric gel columns. In both chromatographic systems, two different calibration curves were built up by using (i γ-Hep chromatographic fractions and the corresponding Mw parameters obtained via HP-SEC/TDA; (ii the whole γ-Hep preparation with broad Mw dispersion and the corresponding cumulative distribution function calculated via HP-SEC/TDA. In addition, also a chromatographic column calibration according to European Pharmacopoeia indication was built up. By comparing all the obtained results, some important differences among Mw and size distribution values of the three LMWHs were found with the five different calibration methods and with HP-SEC/TDA method. In particular, the detection of

  15. New Regimes of Implosions of Larger Sized Wire Arrays With and Without Modified Central Plane at 1.5-1.7 MA Zebra

    Science.gov (United States)

    Safronova, A. S.; Kantsyrev, V. L.; Esaulov, A. A.; Weller, M. E.; Shrestha, I.; Shlyaptseva, V. V.; Stafford, A.; Keim, S. F.; Petkov, E. E.; Lorance, M.; Chuvatin, A. S.; Coverdale, C. A.; Jones, B.

    2013-10-01

    The recent experiments at 1.5-1.7 MA on Zebra at UNR with larger sized planar wires arrays (compared to the wire loads at 1 MA current) have demonstrated higher linear radiation yield and electron temperatures as well as advantages of better diagnostics access to observable plasma regions. Such multi-planar wire arrays had two outer wire planes from mid-Z material to create a global magnetic field (gmf) and mid-Z plasma flow between them. Also, they included a modified central plane with a few Al wires at the edges to influence gmf and to create Al plasma flow in the perpendicular direction. The stationary shock waves which existed over tens of ns on shadow images and the early x-ray emissions before the PCD peak on time-gated spectra were observed. The most recent experiments with similar loads but without the central wires demonstrated a very different regime of implosion with asymmetrical jets and no precursor formation. This work was supported by NNSA under DOE Cooperative Agreement DE-NA0001984 and in part by DE-FC52-06NA27616. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the U.S. Department of Energy's National Nuclear Security Administration under Contract DE-AC04-94AL85000.

  16. Molecular structure of dextran sulphate sodium in aqueous environment

    Science.gov (United States)

    Yu, Miao; Every, Hayley A.; Jiskoot, Wim; Witkamp, Geert-Jan; Buijs, Wim

    2018-03-01

    Here we propose a 3D-molecular structural model for dextran sulphate sodium (DSS) in a neutral aqueous environment based on the results of a molecular modelling study. The DSS structure is dominated by the stereochemistry of the 1,6-linked α-glucose units and the presence of two sulphate groups on each α-glucose unit. The structure of DSS can be best described as a helix with various patterns of di-sulphate substitution on the glucose rings. The presence of a side chain does not alter the 3D-structure of the linear main chain much, but affects the overall spatial dimension of the polymer. The simulated polymers have a diameter similar to or in some cases even larger than model α-hemolysin nano-pores for macromolecule transport in many biological processes, indicating a size-limited translocation through such pores. All results of the molecular modelling study are in line with previously reported experimental data. This study establishes the three-dimensional structure of DSS and summarizes the spatial dimension of the polymer, serving as the basis for a better understanding on the molecular level of DSS-involved electrostatic interaction processes with biological components like proteins and cell pores.

  17. Speaker Input Variability Does Not Explain Why Larger Populations Have Simpler Languages.

    Science.gov (United States)

    Atkinson, Mark; Kirby, Simon; Smith, Kenny

    2015-01-01

    A learner's linguistic input is more variable if it comes from a greater number of speakers. Higher speaker input variability has been shown to facilitate the acquisition of phonemic boundaries, since data drawn from multiple speakers provides more information about the distribution of phonemes in a speech community. It has also been proposed that speaker input variability may have a systematic influence on individual-level learning of morphology, which can in turn influence the group-level characteristics of a language. Languages spoken by larger groups of people have less complex morphology than those spoken in smaller communities. While a mechanism by which the number of speakers could have such an effect is yet to be convincingly identified, differences in speaker input variability, which is thought to be larger in larger groups, may provide an explanation. By hindering the acquisition, and hence faithful cross-generational transfer, of complex morphology, higher speaker input variability may result in structural simplification. We assess this claim in two experiments which investigate the effect of such variability on language learning, considering its influence on a learner's ability to segment a continuous speech stream and acquire a morphologically complex miniature language. We ultimately find no evidence to support the proposal that speaker input variability influences language learning and so cannot support the hypothesis that it explains how population size determines the structural properties of language.

  18. A molecular-sized optical logic circuit for digital modulation of a fluorescence signal

    Science.gov (United States)

    Nishimura, Takahiro; Tsuchida, Karin; Ogura, Yusuke; Tanida, Jun

    2018-03-01

    Fluorescence measurement allows simultaneous detection of multiple molecular species by using spectrally distinct fluorescence probes. However, due to the broad spectra of fluorescence emission, the multiplicity of fluorescence measurement is generally limited. To overcome this limitation, we propose a method to digitally modulate fluorescence output signals with a molecular-sized optical logic circuit by using optical control of fluorescence resonance energy transfer (FRET). The circuit receives a set of optical inputs represented with different light wavelengths, and then it switches high and low fluorescence intensity from a reporting molecule according to the result of the logic operation. By using combinational optical inputs in readout of fluorescence signals, the number of biomolecular species that can be identified is increased. To implement the FRET-based circuits, we designed two types of basic elements, YES and NOT switches. An YES switch produces a high-level output intensity when receiving a designated light wavelength input and a low-level intensity without the light irradiation. A NOT switch operates inversely to the YES switch. In experiments, we investigated the operation of the YES and NOT switches that receive a 532-nm light input and modulate the fluorescence intensity of Alexa Fluor 488. The experimental result demonstrates that the switches can modulate fluorescence signals according to the optical input.

  19. GS6, a member of the GRAS gene family, negatively regulates grain size in rice.

    Science.gov (United States)

    Sun, Lianjun; Li, Xiaojiao; Fu, Yongcai; Zhu, Zuofeng; Tan, Lubin; Liu, Fengxia; Sun, Xianyou; Sun, Xuewen; Sun, Chuanqing

    2013-10-01

    Grain size is an important yield-related trait in rice. Intensive artificial selection for grain size during domestication is evidenced by the larger grains of most of today's cultivars compared with their wild relatives. However, the molecular genetic control of rice grain size is still not well characterized. Here, we report the identification and cloning of Grain Size 6 (GS6), which plays an important role in reducing grain size in rice. A premature stop at the +348 position in the coding sequence (CDS) of GS6 increased grain width and weight significantly. Alignment of the CDS regions of GS6 in 90 rice materials revealed three GS6 alleles. Most japonica varieties (95%) harbor the Type I haplotype, and 62.9% of indica varieties harbor the Type II haplotype. Association analysis revealed that the Type I haplotype tends to increase the width and weight of grains more than either of the Type II or Type III haplotypes. Further investigation of genetic diversity and the evolutionary mechanisms of GS6 showed that the GS6 gene was strongly selected in japonica cultivars. In addition, a "ggc" repeat region identified in the region that encodes the GRAS domain of GS6 played an important historic role in the domestication of grain size in rice. Knowledge of the function of GS6 might aid efforts to elucidate the molecular mechanisms that control grain development and evolution in rice plants, and could facilitate the genetic improvement of rice yield. © 2013 Institute of Botany, Chinese Academy of Sciences.

  20. Explicit all-atom modeling of realistically sized ligand-capped nanocrystals

    KAUST Repository

    Kaushik, Ananth P.

    2012-01-01

    We present a study of an explicit all-atom representation of nanocrystals of experimentally relevant sizes (up to 6 nm), capped with alkyl chain ligands, in vacuum. We employ all-atom molecular dynamics simulation methods in concert with a well-tested intermolecular potential model, MM3 (molecular mechanics 3), for the studies presented here. These studies include determining the preferred conformation of an isolated single nanocrystal (NC), pairs of isolated NCs, and (presaging studies of superlattice arrays) unit cells of NC superlattices. We observe that very small NCs (3 nm) behave differently in a superlattice as compared to larger NCs (6 nm and above) due to the conformations adopted by the capping ligands on the NC surface. Short ligands adopt a uniform distribution of orientational preferences, including some that lie against the face of the nanocrystal. In contrast, longer ligands prefer to interdigitate. We also study the effect of changing ligand length and ligand coverage on the NCs on the preferred ligand configurations. Since explicit all-atom modeling constrains the maximum system size that can be studied, we discuss issues related to coarse-graining the representation of the ligands, including a comparison of two commonly used coarse-grained models. We find that care has to be exercised in the choice of coarse-grained model. The data provided by these realistically sized ligand-capped NCs, determined using explicit all-atom models, should serve as a reference standard for future models of coarse-graining ligands using united atom models, especially for self-assembly processes. © 2012 American Institute of Physics.

  1. The discrepancy between emotional vs. rational estimates of body size, actual size, and ideal body ratings: theoretical and clinical implications.

    Science.gov (United States)

    Thompson, J K; Dolce, J J

    1989-05-01

    Thirty-two asymptomatic college females were assessed on multiple aspects of body image. Subjects' estimation of the size of three body sites (waist, hips, thighs) was affected by instructional protocol. Emotional ratings, based on how they "felt" about their body, elicited ratings that were larger than actual and ideal size measures. Size ratings based on rational instructions were no different from actual sizes, but were larger than ideal ratings. There were no differences between actual and ideal sizes. The results are discussed with regard to methodological issues involved in body image research. In addition, a working hypothesis that differentiates affective/emotional from cognitive/rational aspects of body size estimation is offered to complement current theories of body image. Implications of the findings for the understanding of body image and its relationship to eating disorders are discussed.

  2. Molecular dynamics simulation of equilibrium configurations of plasmas containing multi-species dusts

    International Nuclear Information System (INIS)

    Liu, Yanhong; Chew, Lock Yue

    2007-01-01

    Equilibrium configurations of dusty plasmas with grains of different sizes, which interact through a screened Coulomb force field and confined by a two-dimensional quadratic potential, are studied using molecular dynamics simulation. The system configuration depends on the sizes, masses and charges of the grain species as well as the screening strength of the background plasma. The consideration of the grain size has established a different equilibrium configuration relative to that of point grains. In the new configurations, grains of different species separate into different shells, with the grains of larger mass and charge located away from the system center, forming a shell that surrounds the grains of smaller mass and charge at the system center. This configuration occurs beyond a critical grain radius, and its structure and size are determined by the competing effects between the inter-grain electrostatic repulsive force, the screening effect of the plasma and the mass-dependent confinement force of the quadratic potential

  3. A change in competitive context reverses sexual selection on male size.

    Science.gov (United States)

    Kasumovic, M M; Andrade, M C B

    2009-02-01

    In studies of sexual selection, larger size is often argued to increase male fitness, and relatively smaller males are explained by genetic and/or environmental variation. We demonstrate that a size-development life-history trade-off could underlie the maintenance of a broad, unimodal distribution of size in male redback spiders (Latrodectus hasselti). Larger males are superior in direct competition, but redback males mature rapidly at small size in the presence of females. In field enclosures, we simulated two competitive contexts favouring development of divergent male sizes. Relatively smaller males lost when competing directly, but had 10 times higher fitness than relatively larger males when given the temporal advantage of rapid development. Linear selection gradients confirmed the reversal of selection on size, showing that it is critical to consider life-history decisions underlying the development of traits related to fitness.

  4. ALMA REVEALS THE ANATOMY OF THE mm-SIZED DUST AND MOLECULAR GAS IN THE HD 97048 DISK

    Energy Technology Data Exchange (ETDEWEB)

    Walsh, Catherine; Maud, Luke T. [Leiden Observatory, Leiden University, P.O. Box 9531, 2300 RA Leiden (Netherlands); Juhász, Attila [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Meeus, Gwendolyn [Departamento de Física Teórica, Universidad Autonoma de Madrid, Campus Cantoblanco, E-28049 Madrid (Spain); Dent, William R. F. [Joint ALMA Observatory (JAO), Alonso de Córdova 3107, Vitacura, Santiago (Chile); Aikawa, Yuri [Center for Computer Sciences, University of Tsukuba, 305-8577 Tsukuba (Japan); Millar, Tom J. [School of Mathematics and Physics, Queen’s University Belfast, University Road, Belfast BT7 1NN (United Kingdom); Nomura, Hideko, E-mail: cwalsh@strw.leidenuniv.nl, E-mail: c.walsh1@leeds.ac.uk [Department of Earth and Planetary Science, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, 152-8551 Tokyo (Japan)

    2016-11-10

    Transitional disks show a lack of excess emission at infrared wavelengths due to a large dust cavity, that is often corroborated by spatially resolved observations at ∼ mm wavelengths. We present the first spatially resolved ∼ mm-wavelength images of the disk around the Herbig Ae/Be star, HD 97048. Scattered light images show that the disk extends to ≈640 au. ALMA data reveal a circular-symmetric dusty disk extending to ≈350 au, and a molecular disk traced in CO J = 3-2 emission, extending to ≈750 au. The CO emission arises from a flared layer with an opening angle ≈30°–40°. HD 97048 is another source for which the large (∼ mm-sized) dust grains are more centrally concentrated than the small (∼ μ m-sized) grains and molecular gas, likely due to radial drift. The images and visibility data modeling suggest a decrement in continuum emission within ≈50 au, consistent with the cavity size determined from mid-infrared imaging (34 ± 4 au). The extracted continuum intensity profiles show ring-like structures with peaks at ≈50, 150, and 300 au, with associated gaps at ≈100 and 250 au. This structure should be confirmed in higher-resolution images (FWHM ≈ 10–20 au). These data confirm the classification of HD 97048 as a transitional disk that also possesses multiple ring-like structures in the dust continuum emission. Additional data are required at multiple and well-separated frequencies to fully characterize the disk structure, and thereby constrain the mechanism(s) responsible for sculpting the HD 97048 disk.

  5. ALMA Reveals the Anatomy of the mm-sized Dust and Molecular Gas in the HD 97048 Disk

    Science.gov (United States)

    Walsh, Catherine; Juhász, Attila; Meeus, Gwendolyn; Dent, William R. F.; Maud, Luke T.; Aikawa, Yuri; Millar, Tom J.; Nomura, Hideko

    2016-11-01

    Transitional disks show a lack of excess emission at infrared wavelengths due to a large dust cavity, that is often corroborated by spatially resolved observations at ˜ mm wavelengths. We present the first spatially resolved ˜ mm-wavelength images of the disk around the Herbig Ae/Be star, HD 97048. Scattered light images show that the disk extends to ≈640 au. ALMA data reveal a circular-symmetric dusty disk extending to ≈350 au, and a molecular disk traced in CO J = 3-2 emission, extending to ≈750 au. The CO emission arises from a flared layer with an opening angle ≈30°-40°. HD 97048 is another source for which the large (˜ mm-sized) dust grains are more centrally concentrated than the small (˜μm-sized) grains and molecular gas, likely due to radial drift. The images and visibility data modeling suggest a decrement in continuum emission within ≈50 au, consistent with the cavity size determined from mid-infrared imaging (34 ± 4 au). The extracted continuum intensity profiles show ring-like structures with peaks at ≈50, 150, and 300 au, with associated gaps at ≈100 and 250 au. This structure should be confirmed in higher-resolution images (FWHM ≈ 10-20 au). These data confirm the classification of HD 97048 as a transitional disk that also possesses multiple ring-like structures in the dust continuum emission. Additional data are required at multiple and well-separated frequencies to fully characterize the disk structure, and thereby constrain the mechanism(s) responsible for sculpting the HD 97048 disk.

  6. ALMA REVEALS THE ANATOMY OF THE mm-SIZED DUST AND MOLECULAR GAS IN THE HD 97048 DISK

    International Nuclear Information System (INIS)

    Walsh, Catherine; Maud, Luke T.; Juhász, Attila; Meeus, Gwendolyn; Dent, William R. F.; Aikawa, Yuri; Millar, Tom J.; Nomura, Hideko

    2016-01-01

    Transitional disks show a lack of excess emission at infrared wavelengths due to a large dust cavity, that is often corroborated by spatially resolved observations at ∼ mm wavelengths. We present the first spatially resolved ∼ mm-wavelength images of the disk around the Herbig Ae/Be star, HD 97048. Scattered light images show that the disk extends to ≈640 au. ALMA data reveal a circular-symmetric dusty disk extending to ≈350 au, and a molecular disk traced in CO J = 3-2 emission, extending to ≈750 au. The CO emission arises from a flared layer with an opening angle ≈30°–40°. HD 97048 is another source for which the large (∼ mm-sized) dust grains are more centrally concentrated than the small (∼ μ m-sized) grains and molecular gas, likely due to radial drift. The images and visibility data modeling suggest a decrement in continuum emission within ≈50 au, consistent with the cavity size determined from mid-infrared imaging (34 ± 4 au). The extracted continuum intensity profiles show ring-like structures with peaks at ≈50, 150, and 300 au, with associated gaps at ≈100 and 250 au. This structure should be confirmed in higher-resolution images (FWHM ≈ 10–20 au). These data confirm the classification of HD 97048 as a transitional disk that also possesses multiple ring-like structures in the dust continuum emission. Additional data are required at multiple and well-separated frequencies to fully characterize the disk structure, and thereby constrain the mechanism(s) responsible for sculpting the HD 97048 disk.

  7. Polymer friction Molecular Dynamics

    DEFF Research Database (Denmark)

    Sivebæk, Ion Marius; Samoilov, Vladimir N.; Persson, Bo N. J.

    We present molecular dynamics friction calculations for confined hydrocarbon solids with molecular lengths from 20 to 1400 carbon atoms. Two cases are considered: a) polymer sliding against a hard substrate, and b) polymer sliding on polymer. In the first setup the shear stresses are relatively...... independent of molecular length. For polymer sliding on polymer the friction is significantly larger, and dependent on the molecular chain length. In both cases, the shear stresses are proportional to the squeezing pressure and finite at zero load, indicating an adhesional contribution to the friction force....

  8. The influence of molecular architecture and solvent type on the size and structure of poly(benzyl ether) dendrimers by SANS

    NARCIS (Netherlands)

    Evmenenko, G.; Bauer, B.J.; Kleppinger, R.; Forier, B.; Dehaen, W.; Amis, E.J.; Mischenko, N.; Reynaers, H.

    2001-01-01

    The size of poly(benzyl ether) dendrimers with different molecular architectures was measured by small angle neutron scattering (SANS). Both polar and non-polar solvents were used to measure the effect of solvent type. The radius of gyration (Rg) of all of the dendrimers follows a scaling law of Rg

  9. Population genomics of eusocial insects: the costs of a vertebrate-like effective population size.

    Science.gov (United States)

    Romiguier, J; Lourenco, J; Gayral, P; Faivre, N; Weinert, L A; Ravel, S; Ballenghien, M; Cahais, V; Bernard, A; Loire, E; Keller, L; Galtier, N

    2014-03-01

    The evolution of reproductive division of labour and social life in social insects has lead to the emergence of several life-history traits and adaptations typical of larger organisms: social insect colonies can reach masses of several kilograms, they start reproducing only when they are several years old, and can live for decades. These features and the monopolization of reproduction by only one or few individuals in a colony should affect molecular evolution by reducing the effective population size. We tested this prediction by analysing genome-wide patterns of coding sequence polymorphism and divergence in eusocial vs. noneusocial insects based on newly generated RNA-seq data. We report very low amounts of genetic polymorphism and an elevated ratio of nonsynonymous to synonymous changes – a marker of the effective population size – in four distinct species of eusocial insects, which were more similar to vertebrates than to solitary insects regarding molecular evolutionary processes. Moreover, the ratio of nonsynonymous to synonymous substitutions was positively correlated with the level of social complexity across ant species. These results are fully consistent with the hypothesis of a reduced effective population size and an increased genetic load in eusocial insects, indicating that the evolution of social life has important consequences at both the genomic and population levels. © 2014 The Authors. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

  10. Plant Size and Competitive Dynamics along Nutrient Gradients.

    Science.gov (United States)

    Goldberg, Deborah E; Martina, Jason P; Elgersma, Kenneth J; Currie, William S

    2017-08-01

    Resource competition theory in plants has focused largely on resource acquisition traits that are independent of size, such as traits of individual leaves or roots or proportional allocation to different functions. However, plants also differ in maximum potential size, which could outweigh differences in module-level traits. We used a community ecosystem model called mondrian to investigate whether larger size inevitably increases competitive ability and how size interacts with nitrogen supply. Contrary to the conventional wisdom that bigger is better, we found that invader success and competitive ability are unimodal functions of maximum potential size, such that plants that are too large (or too small) are disproportionately suppressed by competition. Optimal size increases with nitrogen supply, even when plants compete for nitrogen only in a size-symmetric manner, although adding size-asymmetric competition for light does substantially increase the advantage of larger size at high nitrogen. These complex interactions of plant size and nitrogen supply lead to strong nonlinearities such that small differences in nitrogen can result in large differences in plant invasion success and the influence of competition along productivity gradients.

  11. Extraction Kinetics and Molecular Size Fractionation of Humic Substances From Two Brazilian Soils

    Directory of Open Access Journals (Sweden)

    Dick Deborah Pinheiro

    1999-01-01

    Full Text Available In the present study, the extraction behaviour of humic substances (HS from an Oxisol and a Mollisol from South Brazil, by using 0.1 and 0.5 mol L-1 NaOH and 0.15 mol L-1 neutral pyrophosphate solutions, respectively, was systematically studied. The kinetics and efficiency of HS extraction were evaluated by means of UV/Vis spectroscopy. The isolated humic acids (HA and fulvic acids (FA were size-classified by multistage ultrafiltration (six fractions in the molecular weight range of 1 to 100 kDa. The obtained data show that the HS extraction yield depended not only on the extractant, but also on the soil type. Within 3 h approximately 90% of the soluble HS could be extracted following complex extraction kinetics by both methods and none or little structural modification was verified as observed from their stable extinction ratio E350/E550. In the Mollisol the pyrophosphate extraction was more effective, suggesting that a great part of HS occurred as macromolecules bonded to clay minerals and aggregated between themselves through cationic bridges. In the Oxisol a higher HS yield was verified with the alkaline method, presumably due to HS fixation onto the oxide surface by H-bonds and/or surface complexation reactions. In general, HS extracted by the pyrophosphate procedure showed higher molecular weights than those extracted by NaOH.

  12. Zooplankton size selection relative to gill raker spacing in rainbow trout

    Science.gov (United States)

    Budy, P.; Haddix, T.; Schneidervin, R.

    2005-01-01

    Rainbow trout Oncorhynchus mykiss are one of the most widely stocked salmonids worldwide, often based on the assumption that they will effectively utilize abundant invertebrate food resources. We evaluated the potential for feeding morphology to affect prey selection by rainbow trout using a combination of laboratory feeding experiments and field observations in Flaming Gorge Reservoir, Utah-Wyoming. For rainbow trout collected from the reservoir, inter-gill raker spacing averaged 1.09 mm and there was low variation among fish overall (SD = 0.28). Ninety-seven percent of all zooplankton observed in the diets of rainbow trout collected in the reservoir were larger than the interraker spacing, while only 29% of the zooplankton found in the environment were larger than the interraker spacing. Over the size range of rainbow trout evaluated here (200-475 mm), interraker spacing increased moderately with increasing fish length; however, the size of zooplankton found in the diet did not increase with increasing fish length. In laboratory experiments, rainbow trout consumed the largest zooplankton available; the mean size of zooplankton observed in the diets was significantly larger than the mean size of zooplankton available. Electivity indices for both laboratory and field observations indicated strong selection for larger-sized zooplankton. The size threshold at which electivity switched from selection against smaller-sized zooplankton to selection for larger-sized zooplankton closely corresponded to the mean interraker spacing for both groups (???1-1.2 mm). The combination of results observed here indicates that rainbow trout morphology limits the retention of different-sized zooplankton prey and reinforces the importance of understanding how effectively rainbow trout can utilize the type and sizes of different prey available in a given system. These considerations may improve our ability to predict the potential for growth and survival of rainbow trout within and

  13. Polymorphism of fibrillar structures depending on the size of assembled Aβ17-42 peptides

    Science.gov (United States)

    Cheon, Mookyung; Kang, Mooseok; Chang, Iksoo

    2016-01-01

    The size of assembled Aβ17-42 peptides can determine polymorphism during oligomerization and fibrillization, but the mechanism of this effect is unknown. Starting from separate random monomers, various fibrillar oligomers with distinct structural characteristics were identified using discontinuous molecular dynamics simulations based on a coarse-grained protein model. From the structures observed in the simulations, two characteristic oligomer sizes emerged, trimer and paranuclei, which generated distinct structural patterns during fibrillization. A majority of the simulations for trimers and tetramers formed non-fibrillar oligomers, which primarily progress to off-pathway oligomers. Pentamers and hexamers were significantly converted into U-shape fibrillar structures, meaning that these oligomers, called paranuclei, might be potent on-pathway intermediates in fibril formation. Fibrillar oligomers larger than hexamers generated substantial polymorphism in which hybrid structures were readily formed and homogeneous fibrillar structures appeared infrequently. PMID:27901087

  14. Body Size, Fecundity, and Sexual Size Dimorphism in the Neotropical Cricket Macroanaxipha macilenta (Saussure) (Orthoptera: Gryllidae).

    Science.gov (United States)

    Cueva Del Castillo, R

    2015-04-01

    Body size is directly or indirectly correlated with fitness. Body size, which conveys maximal fitness, often differs between sexes. Sexual size dimorphism (SSD) evolves because body size tends to be related to reproductive success through different pathways in males and females. In general, female insects are larger than males, suggesting that natural selection for high female fecundity could be stronger than sexual selection in males. I assessed the role of body size and fecundity in SSD in the Neotropical cricket Macroanaxipha macilenta (Saussure). This species shows a SSD bias toward males. Females did not present a correlation between number of eggs and body size. Nonetheless, there were fluctuations in the number of eggs carried by females during the sampling period, and the size of females that were collected carrying eggs was larger than that of females collected with no eggs. Since mating induces vitellogenesis in some cricket species, differences in female body size might suggest male mate choice. Sexual selection in the body size of males of M. macilenta may possibly be stronger than the selection of female fecundity. Even so, no mating behavior was observed during the field observations, including audible male calling or courtship songs, yet males may produce ultrasonic calls due to their size. If female body size in M. macilenta is not directly related to fecundity, the lack of a correlated response to selection on female body size could represent an alternate evolutionary pathway in the evolution of body size and SSD in insects.

  15. Molecular dynamics study on microstructure of near grain boundary distortion region in small grain size nano- NiAl alloy

    International Nuclear Information System (INIS)

    Wang, J.Y.; Wang, X.W.; Rifkin, J.; Li, D.X.

    2001-12-01

    Using the molecular dynamics simulation method, the microstructure of distortion region near curved amorphous-like grain boundary in nano-NiAl alloy is studied. The results showed that due to the internal elastic force of high energy grain boundary, distortion layer exists between grain and grain boundary. The lattice expansion and structure factor decreasing are observed in this region. Stacking fault in sample with grain size 3.8nm is clearly observed across the distortion region at the site very close to grain. The influences of different grain sizes on average distortion degree and volume fractions of distortion region, grain and grain boundary are also discussed. (author)

  16. [Effect sizes, statistical power and sample sizes in "the Japanese Journal of Psychology"].

    Science.gov (United States)

    Suzukawa, Yumi; Toyoda, Hideki

    2012-04-01

    This study analyzed the statistical power of research studies published in the "Japanese Journal of Psychology" in 2008 and 2009. Sample effect sizes and sample statistical powers were calculated for each statistical test and analyzed with respect to the analytical methods and the fields of the studies. The results show that in the fields like perception, cognition or learning, the effect sizes were relatively large, although the sample sizes were small. At the same time, because of the small sample sizes, some meaningful effects could not be detected. In the other fields, because of the large sample sizes, meaningless effects could be detected. This implies that researchers who could not get large enough effect sizes would use larger samples to obtain significant results.

  17. Evaporation of liquid droplets of nano- and micro-meter size as a function of molecular mass and intermolecular interactions: experiments and molecular dynamics simulations.

    Science.gov (United States)

    Hołyst, Robert; Litniewski, Marek; Jakubczyk, Daniel

    2017-09-13

    Transport of heat to the surface of a liquid is a limiting step in the evaporation of liquids into an inert gas. Molecular dynamics (MD) simulations of a two component Lennard-Jones (LJ) fluid revealed two modes of energy transport from a vapour to an interface of an evaporating droplet of liquid. Heat is transported according to the equation of temperature diffusion, far from the droplet of radius R. The heat flux, in this region, is proportional to temperature gradient and heat conductivity in the vapour. However at some distance from the interface, Aλ, (where λ is the mean free path in the gas), the temperature has a discontinuity and heat is transported ballistically i.e. by direct individual collisions of gas molecules with the interface. This ballistic transport reduces the heat flux (and consequently the mass flux) by the factor R/(R + Aλ) in comparison to the flux obtained from temperature diffusion. Thus it slows down the evaporation of droplets of sizes R ∼ Aλ and smaller (practically for sizes from 10 3 nm down to 1 nm). We analyzed parameter A as a function of interactions between molecules and their masses. The rescaled parameter, A(k B T b /ε 11 ) 1/2 , is a linear function of the ratio of the molecular mass of the liquid molecules to the molecular mass of the gas molecules, m 1 /m 2 (for a series of chemically similar compounds). Here ε 11 is the interaction parameter between molecules in the liquid (proportional to the enthalpy of evaporation) and T b is the temperature of the gas in the bulk. We tested the predictions of MD simulations in experiments performed on droplets of ethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol. They were suspended in an electrodynamic trap and evaporated into dry nitrogen gas. A changes from ∼1 (for ethylene glycol) to approximately 10 (for tetraethylene glycol) and has the same dependence on molecular parameters as obtained for the LJ fluid in MD simulations. The value of x = A

  18. Relation between the ion size and pore size for an electric double-layer capacitor.

    Science.gov (United States)

    Largeot, Celine; Portet, Cristelle; Chmiola, John; Taberna, Pierre-Louis; Gogotsi, Yury; Simon, Patrice

    2008-03-05

    The research on electrochemical double layer capacitors (EDLC), also known as supercapacitors or ultracapacitors, is quickly expanding because their power delivery performance fills the gap between dielectric capacitors and traditional batteries. However, many fundamental questions, such as the relations between the pore size of carbon electrodes, ion size of the electrolyte, and the capacitance have not yet been fully answered. We show that the pore size leading to the maximum double-layer capacitance of a TiC-derived carbon electrode in a solvent-free ethyl-methylimmidazolium-bis(trifluoro-methane-sulfonyl)imide (EMI-TFSI) ionic liquid is roughly equal to the ion size (approximately 0.7 nm). The capacitance values of TiC-CDC produced at 500 degrees C are more than 160 F/g and 85 F/cm(3) at 60 degrees C, while standard activated carbons with larger pores and a broader pore size distribution present capacitance values lower than 100 F/g and 50 F/cm(3) in ionic liquids. A significant drop in capacitance has been observed in pores that were larger or smaller than the ion size by just an angstrom, suggesting that the pore size must be tuned with sub-angstrom accuracy when selecting a carbon/ion couple. This work suggests a general approach to EDLC design leading to the maximum energy density, which has been now proved for both solvated organic salts and solvent-free liquid electrolytes.

  19. Visual exposure to large and small portion sizes and perceptions of portion size normality: Three experimental studies

    OpenAIRE

    Robinson, Eric; Oldham, Melissa; Cuckson, Imogen; Brunstrom, Jeffrey M.; Rogers, Peter J.; Hardman, Charlotte A.

    2016-01-01

    Portion sizes of many foods have increased in recent times. In three studies we examined the effect that repeated visual exposure to larger versus smaller food portion sizes has on perceptions of what constitutes a normal-sized food portion and measures of portion size selection. In studies 1 and 2 participants were visually exposed to images of large or small portions of spaghetti bolognese, before making evaluations about an image of an intermediate sized portion of the same food. In study ...

  20. Mean size estimation yields left-side bias: Role of attention on perceptual averaging.

    Science.gov (United States)

    Li, Kuei-An; Yeh, Su-Ling

    2017-11-01

    The human visual system can estimate mean size of a set of items effectively; however, little is known about whether information on each visual field contributes equally to the mean size estimation. In this study, we examined whether a left-side bias (LSB)-perceptual judgment tends to depend more heavily on left visual field's inputs-affects mean size estimation. Participants were instructed to estimate the mean size of 16 spots. In half of the trials, the mean size of the spots on the left side was larger than that on the right side (the left-larger condition) and vice versa (the right-larger condition). Our results illustrated an LSB: A larger estimated mean size was found in the left-larger condition than in the right-larger condition (Experiment 1), and the LSB vanished when participants' attention was effectively cued to the right side (Experiment 2b). Furthermore, the magnitude of LSB increased with stimulus-onset asynchrony (SOA), when spots on the left side were presented earlier than the right side. In contrast, the LSB vanished and then induced a reversed effect with SOA when spots on the right side were presented earlier (Experiment 3). This study offers the first piece of evidence suggesting that LSB does have a significant influence on mean size estimation of a group of items, which is induced by a leftward attentional bias that enhances the prior entry effect on the left side.

  1. De novo DNA sequence driven bulk segregant analysis can pinpoint candicate loci for Total Glycoalkaloid (TGA) content in potato without prior knowledge of molecular markers

    DEFF Research Database (Denmark)

    Kaminski, Kacper Piotr; Sønderkær, Mads; Petersen, Annabeth Høgh

    is discarded based on the absence of desired molecular marker already at the seed or seedling stage. However, the number of molecular markers known in potato with appropriate linkage to agronomical traits is presently insufficient to establish a comprehensive MAS breeding platform for potato.......Potato breeding is a slow and costly affair, primarily done as a classical "mate and phenotype" approach using relatively small populations. In contrast, Marker Assisted Selection (MAS) allows cost-effective screening of much larger effective populations sizes because most of the offspring...

  2. On the Peculiar Molecular Shape and Size Dependence of the Dynamics of Fluids confined in a Small-Pore Metal-Organic Framework

    KAUST Repository

    Skarmoutsos, Ioannis

    2018-05-15

    Force field based-Molecular dynamics simulations were deployed to systematically explore the dynamics of confined molecules of different shapes and sizes, i.e. linear (CO2 and N2) and spherical (CH4) fluids, in a model small pore system, i.e. the Metal-Organic Framework SIFSIX-2-Cu-i. These computations unveil an unprecedented molecular symmetry dependence of the translational and rotational dynamics of fluids confined in channel-like nanoporous materials. In particular this peculiar behaviour is reflected by the extremely slow decay of the Legendre reorientational correlation functions of even-parity order for the linear fluids which is associated to jump-like orientation flips, while the spherical fluid shows a very fast decay taking place in a sub-picosecond time scale. Such a fundamental understanding is relevant to diverse disciplines such as in chemistry, physics, biology and materials science where diatomic or polyatomic molecules of different shapes/sizes diffuse through nanopores.

  3. Magnetic high throughput screening system for the development of nano-sized molecularly imprinted polymers for controlled delivery of curcumin.

    Science.gov (United States)

    Piletska, Elena V; Abd, Bashar H; Krakowiak, Agata S; Parmar, Anitha; Pink, Demi L; Wall, Katie S; Wharton, Luke; Moczko, Ewa; Whitcombe, Michael J; Karim, Kal; Piletsky, Sergey A

    2015-05-07

    Curcumin is a versatile anti-inflammatory and anti-cancer agent known for its low bioavailability, which could be improved by developing materials capable of binding and releasing drug in a controlled fashion. The present study describes the preparation of magnetic nano-sized Molecularly Imprinted Polymers (nanoMIPs) for the controlled delivery of curcumin and their high throughput characterisation using microtitre plates modified with magnetic inserts. NanoMIPs were synthesised using functional monomers chosen with the aid of molecular modelling. The rate of release of curcumin from five polymers was studied under aqueous conditions and was found to correlate well with the binding energies obtained computationally. The presence of specific monomers was shown to be significant in ensuring effective binding of curcumin and to the rate of release obtained. Characterisation of the polymer particles was carried out using dynamic light scattering (DLS) technique and scanning electron microscopy (SEM) in order to establish the relationship between irradiation time and particle size. The protocols optimised during this study could be used as a blueprint for the development of nanoMIPs capable of the controlled release of potentially any compound of interest.

  4. The cavity-nest ant Temnothorax crassispinus prefers larger nests.

    Science.gov (United States)

    Mitrus, S

    Colonies of the ant Temnothorax crassispinus inhabit mostly cavities in wood and hollow acorns. Typically in the field, nest sites that can be used by the ant are a limited resource. In a field experiment, it was investigated whether the ants prefer a specific size of nest, when different ones are available. In July 2011, a total of 160 artificial nests were placed in a beech-pine forest. Four artificial nests (pieces of wood with volume cavities, ca 415, 605, 730, and 980 mm 3 , respectively) were located on each square meter of the experimental plot. One year later, shortly before the emergence of new sexuals, the nests were collected. In July 2012, colonies inhabited more frequently bigger nests. Among queenright colonies, the ones which inhabited bigger nests had more workers. However, there was no relationship between volume of nest and number of workers for queenless colonies. Queenright colonies from bigger nests produced more sexual individuals, but there was no correlation between number of workers and sex allocation ratio, or between volume of nest and sex allocation ratio. In a laboratory experiment where ant colonies were kept in 470 and 860 mm 3 nests, larger colonies allocated more energy to produce sexual individuals. The results of this study show the selectivity of T. crassispinus ants regarding the size of nest cavity, and that the nest volume has an impact on life history parameters.

  5. Molecular characterization of multivalent bioconjugates by size-exclusion chromatography (SEC) with multi-angle laser light scattering (MALS)

    Science.gov (United States)

    Pollock, Jacob F.; Ashton, Randolph S.; Rode, Nikhil A.; Schaffer, David V.; Healy, Kevin E.

    2013-01-01

    The degree of substitution and valency of bioconjugate reaction products are often poorly judged or require multiple time- and product- consuming chemical characterization methods. These aspects become critical when analyzing and optimizing the potency of costly polyvalent bioactive conjugates. In this study, size-exclusion chromatography with multi-angle laser light scattering was paired with refractive index detection and ultraviolet spectroscopy (SEC-MALS-RI-UV) to characterize the reaction efficiency, degree of substitution, and valency of the products of conjugation of either peptides or proteins to a biopolymer scaffold, i.e., hyaluronic acid (HyA). Molecular characterization was more complete compared to estimates from a protein quantification assay, and exploitation of this method led to more accurate deduction of the molecular structures of polymer bioconjugates. Information obtained using this technique can improve macromolecular engineering design principles and better understand multivalent macromolecular interactions in biological systems. PMID:22794081

  6. Determination of nanoparticle size distribution together with density or molecular weight by 2D analytical ultracentrifugation

    KAUST Repository

    Carney, Randy P.; Kim, Jin Young; Qian, Huifeng; Jin, Rongchao; Mehenni, Hakim; Stellacci, Francesco; Bakr, Osman

    2011-01-01

    Nanoparticles are finding many research and industrial applications, yet their characterization remains a challenge. Their cores are often polydisperse and coated by a stabilizing shell that varies in size and composition. No single technique can characterize both the size distribution and the nature of the shell. Advances in analytical ultracentrifugation allow for the extraction of the sedimentation (s) and diffusion coefficients (D). Here we report an approach to transform the s and D distributions of nanoparticles in solution into precise molecular weight (M), density (?P) and particle diameter (dp) distributions. M for mixtures of discrete nanocrystals is found within 4% of the known quantities. The accuracy and the density information we achieve on nanoparticles are unparalleled. A single experimental run is sufficient for full nanoparticle characterization, without the need for standards or other auxiliary measurements. We believe that our method is of general applicability and we discuss its limitations. 2011 Macmillan Publishers Limited. All rights reserved.

  7. Determination of nanoparticle size distribution together with density or molecular weight by 2D analytical ultracentrifugation

    KAUST Repository

    Carney, Randy P.

    2011-06-07

    Nanoparticles are finding many research and industrial applications, yet their characterization remains a challenge. Their cores are often polydisperse and coated by a stabilizing shell that varies in size and composition. No single technique can characterize both the size distribution and the nature of the shell. Advances in analytical ultracentrifugation allow for the extraction of the sedimentation (s) and diffusion coefficients (D). Here we report an approach to transform the s and D distributions of nanoparticles in solution into precise molecular weight (M), density (?P) and particle diameter (dp) distributions. M for mixtures of discrete nanocrystals is found within 4% of the known quantities. The accuracy and the density information we achieve on nanoparticles are unparalleled. A single experimental run is sufficient for full nanoparticle characterization, without the need for standards or other auxiliary measurements. We believe that our method is of general applicability and we discuss its limitations. 2011 Macmillan Publishers Limited. All rights reserved.

  8. Methods for obtaining true particle size distributions from cross section measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lord, Kristina Alyse [Iowa State Univ., Ames, IA (United States)

    2013-01-01

    Sectioning methods are frequently used to measure grain sizes in materials. These methods do not provide accurate grain sizes for two reasons. First, the sizes of features observed on random sections are always smaller than the true sizes of solid spherical shaped objects, as noted by Wicksell [1]. This is the case because the section very rarely passes through the center of solid spherical shaped objects randomly dispersed throughout a material. The sizes of features observed on random sections are inversely related to the distance of the center of the solid object from the section [1]. Second, on a plane section through the solid material, larger sized features are more frequently observed than smaller ones due to the larger probability for a section to come into contact with the larger sized portion of the spheres than the smaller sized portion. As a result, it is necessary to find a method that takes into account these reasons for inaccurate particle size measurements, while providing a correction factor for accurately determining true particle size measurements. I present a method for deducing true grain size distributions from those determined from specimen cross sections, either by measurement of equivalent grain diameters or linear intercepts.

  9. Pressure Enhancement in Confined Fluids: Effect of Molecular Shape and Fluid-Wall Interactions.

    Science.gov (United States)

    Srivastava, Deepti; Santiso, Erik E; Gubbins, Keith E

    2017-10-24

    Recently, several experimental and simulation studies have found that phenomena that normally occur at extremely high pressures in a bulk phase can occur in nanophases confined within porous materials at much lower bulk phase pressures, thus providing an alternative route to study high-pressure phenomena. In this work, we examine the effect on the tangential pressure of varying the molecular shape, strength of the fluid-wall interactions, and pore width, for carbon slit-shaped pores. We find that, for multisite molecules, the presence of additional rotational degrees of freedom leads to unique changes in the shape of the tangential pressure profile, especially in larger pores. We show that, due to the direct relationship between the molecular density and the fluid-wall interactions, the latter have a large impact on the pressure tensor. The molecular shape and pore size have a notable impact on the layering of molecules in the pore, greatly influencing both the shape and scale of the tangential pressure profile.

  10. Social thermoregulation as a potential mechanism linking sociality and fitness: Barbary macaques with more social partners form larger huddles.

    Science.gov (United States)

    Campbell, Liz A D; Tkaczynski, Patrick J; Lehmann, Julia; Mouna, Mohamed; Majolo, Bonaventura

    2018-04-17

    Individuals with more or stronger social bonds experience enhanced survival and reproduction in various species, though the mechanisms mediating these effects are unclear. Social thermoregulation is a common behaviour across many species which reduces cold stress exposure, body heat loss, and homeostatic energy costs, allowing greater energetic investment in growth, reproduction, and survival, with larger aggregations providing greater benefits. If more social individuals form larger thermoregulation aggregations due to having more potential partners, this would provide a direct link between sociality and fitness. We conducted the first test of this hypothesis by studying social relationships and winter sleeping huddles in wild Barbary macaques (Macaca sylvanus), wherein individuals with more social partners experience greater probability of winter survival. Precipitation and low temperature increased huddle sizes, supporting previous research that huddle size influences thermoregulation and energetics. Huddling relationships were predicted by social (grooming) relationships. Individuals with more social partners therefore formed larger huddles, suggesting reduced energy expenditure and exposure to environmental stressors than less social individuals, potentially explaining how sociality affects survival in this population. This is the first evidence that social thermoregulation may be a direct proximate mechanism by which increased sociality enhances fitness, which may be widely applicable across taxa.

  11. Bimodal Nanoparticle Size Distributions Produced by Laser Ablation of Microparticles in Aerosols

    International Nuclear Information System (INIS)

    Nichols, William T.; Malyavanatham, Gokul; Henneke, Dale E.; O'Brien, Daniel T.; Becker, Michael F.; Keto, John W.

    2002-01-01

    Silver nanoparticles were produced by laser ablation of a continuously flowing aerosol of microparticles in nitrogen at varying laser fluences. Transmission electron micrographs were analyzed to determine the effect of laser fluence on the nanoparticle size distribution. These distributions exhibited bimodality with a large number of particles in a mode at small sizes (3-6-nm) and a second, less populated mode at larger sizes (11-16-nm). Both modes shifted to larger sizes with increasing laser fluence, with the small size mode shifting by 35% and the larger size mode by 25% over a fluence range of 0.3-4.2-J/cm 2 . Size histograms for each mode were found to be well represented by log-normal distributions. The distribution of mass displayed a striking shift from the large to the small size mode with increasing laser fluence. These results are discussed in terms of a model of nanoparticle formation from two distinct laser-solid interactions. Initially, laser vaporization of material from the surface leads to condensation of nanoparticles in the ambient gas. Material evaporation occurs until the plasma breakdown threshold of the microparticles is reached, generating a shock wave that propagates through the remaining material. Rapid condensation of the vapor in the low-pressure region occurs behind the traveling shock wave. Measurement of particle size distributions versus gas pressure in the ablation region, as well as, versus microparticle feedstock size confirmed the assignment of the larger size mode to surface-vaporization and the smaller size mode to shock-formed nanoparticles

  12. Molecular Dynamics Studies of Thermal Induced Chemistry in Tatb

    Science.gov (United States)

    Quenneville, J.; Germann, T. C.; Thompson, A. P.; Kober, E. M.

    2007-12-01

    A reactive force field (ReaxFF) is used with molecular dynamics to probe the chemistry induced by intense heating (`accelerated cook-off') of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). Large-system simulations are desired for TATB because of the high degree of carbon clustering expected in this material. Using small, 32-molecule simulations, we calculate the reaction rate as a function of temperature and compare the Arrhenius-predicted activation energy with experiment. Decomposition product evolution (mainly N2, H2O, CO2 and graphitic carbon clusters) is followed using a 576-molecule larger simulation, which also illustrates the effect of system size on both carbon clustering and reaction rate.

  13. Sexual differences in post-hatching Saunders's gulls: size, locomotor activity, and foraging skill.

    Science.gov (United States)

    Yoon, Jongmin; Lee, Seung-Hee; Joo, Eun-Jin; Na, Ki-Jeong; Park, Shi-Ryong

    2013-04-01

    Various selection pressures induce the degree and direction of sexual size dimorphism in animals. Selection favors either larger males for contests over mates or resources, or smaller males are favored for maneuverability; whereas larger females are favored for higher fecundity, or smaller females for earlier maturation for reproduction. In the genus of Larus (seagulls), adult males are generally known to be larger in size than adult females. However, the ontogeny of sexual size dimorphism is not well understood, compared to that in adults. The present study investigates the ontogeny of sexual size dimorphism in Saunders's gulls (Larus saundersi) in captivity. We artificially incubated fresh eggs collected in Incheon, South Korea, and measured body size, locomotor activity, and foraging skill in post-hatching chicks in captivity. Our results indicated that the sexual differences in size and locomotor activity occurred with the post-hatching development. Also, larger males exhibited greater foraging skills for food acquisition than smaller females at 200 days of age. Future studies should assess how the adaptive significance of the sexual size dimorphism in juveniles is linked with sexual divergence in survival rates, intrasexual contests, or parental effort in sexes.

  14. An analytical procedure to evaluate electronic integrals for molecular quantum mechanical calculations

    International Nuclear Information System (INIS)

    Mundim, Kleber C.

    2004-01-01

    Full text: We propose an alternative methodology for the calculation of electronic integrals, through an analytical function based on the generalized Gaussian function (q Gaussian), where a single q Gaussian replaces the usual linear combination of Gaussian functions for different basis set. Moreover, the integrals become analytical functions of the interatomic distances. Therefore, when estimating certain quantities such as molecular energy, g Gaussian avoid new calculations of the integrals: they are simply another value of the corresponding function. The procedure proposed here is particularly advantageous, when compared with the usual one, because it reduces drastically the number of two-electronic integrals used in the construction of the Fock matrix, enabling the use of the quantum mechanics in the description of macro-molecular systems. This advantage increases when the size of the molecular systems become larger and more complex. While in the usual approach CPU time increases with n4, in the one proposed here the CPU time scales linearly with n. This catastrophic dependence of the rank the Hamiltonian or Fock matrix with n4 two-electron integrals is a severe bottleneck for petaFLOPS computing time. Its is important to emphasize that this methodology is equally applicable to systems of any sizes, including biomolecules, solid materials and solutions, within the HF, post-HF and DFT theories. (author)

  15. Contributions of molecular size, charge distribution, and specific amino acids to the iron-binding capacity of sea cucumber (Stichopus japonicus) ovum hydrolysates.

    Science.gov (United States)

    Sun, Na; Cui, Pengbo; Jin, Ziqi; Wu, Haitao; Wang, Yixing; Lin, Songyi

    2017-09-01

    This study investigated the contributions of molecular size, charge distribution and specific amino acids to the iron-binding capacity of sea cucumber (Stichopus japonicus) ovum hydrolysates (SCOHs), and further explored their iron-binding sites. It was demonstrated that enzyme type and degree of hydrolysis (DH) significantly influenced the iron-binding capacity of the SCOHs. The SCOHs produced by alcalase at a DH of 25.9% possessed the highest iron-binding capacity at 92.1%. As the hydrolysis time increased, the molecular size of the SCOHs decreased, the negative charges increased, and the hydrophilic amino acids were exposed to the surface, facilitating iron binding. Furthermore, the Fourier transform infrared spectra, combined with amino acid composition analysis, revealed that iron bound to the SCOHs primarily through interactions with carboxyl oxygen of Asp, guanidine nitrogen of Arg or nitrogen atoms in imidazole group of His. The formed SCOHs-iron complexes exhibited a fold and crystal structure with spherical particles. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. The Evolution of Clutch Size in Hosts of Avian Brood Parasites.

    Science.gov (United States)

    Medina, Iliana; Langmore, Naomi E; Lanfear, Robert; Kokko, Hanna

    2017-11-01

    Coevolution with avian brood parasites shapes a range of traits in their hosts, including morphology, behavior, and breeding systems. Here we explore whether brood parasitism is also associated with the evolution of host clutch size. Several studies have proposed that hosts of highly virulent parasites could decrease the costs of parasitism by evolving a smaller clutch size, because hosts with smaller clutches will lose fewer progeny when their clutch is parasitized. We describe a model of the evolution of clutch size, which challenges this logic and shows instead that an increase in clutch size (or no change) should evolve in hosts. We test this prediction using a broad-scale comparative analysis to ask whether there are differences in clutch size within hosts and between hosts and nonhosts. Consistent with our model, this analysis revealed that host species do not have smaller clutches and that hosts that incur larger costs from raising a parasite lay larger clutches. We suggest that brood parasitism might be an influential factor in clutch-size evolution and could potentially select for the evolution of larger clutches in host species.

  17. The Dynamical Imprint of Lost Protoplanets on the Trans-Neptunian Populations, and Limits on the Primordial Size Distribution of Trans-Neptunian Objects at Pluto and Larger Sizes.

    Science.gov (United States)

    Shannon, Andrew Brian; Dawson, Rebekah

    2018-04-01

    Planet formation remains a poorly understood process, in part because of our limited access to the intermediate phases of planetesimal and protoplanet growth. Today, the vast majority of the accessible remaining planetesimals and protoplanets reside within the Hot Trans-Neptunian Object population. This population has been depleted by 99% - 99.9% over the course of the Solar system's history, and as such the present day size-number distribution may be incomplete at the large size end. We show that such lost protoplanets would have left signatures in the dynamics of the present-day Trans-Neptunian Populations, and their primordial number can thus be statistically limited by considering the survival of ultra-wide binary TNOs, the Cold Classical Kuiper belt, and the resonant populations. We compare those limits to the predicted size-number distribution of various planetesimal and proto-planet growth models.

  18. Cation solvation with quantum chemical effects modeled by a size-consistent multi-partitioning quantum mechanics/molecular mechanics method.

    Science.gov (United States)

    Watanabe, Hiroshi C; Kubillus, Maximilian; Kubař, Tomáš; Stach, Robert; Mizaikoff, Boris; Ishikita, Hiroshi

    2017-07-21

    In the condensed phase, quantum chemical properties such as many-body effects and intermolecular charge fluctuations are critical determinants of the solvation structure and dynamics. Thus, a quantum mechanical (QM) molecular description is required for both solute and solvent to incorporate these properties. However, it is challenging to conduct molecular dynamics (MD) simulations for condensed systems of sufficient scale when adapting QM potentials. To overcome this problem, we recently developed the size-consistent multi-partitioning (SCMP) quantum mechanics/molecular mechanics (QM/MM) method and realized stable and accurate MD simulations, using the QM potential to a benchmark system. In the present study, as the first application of the SCMP method, we have investigated the structures and dynamics of Na + , K + , and Ca 2+ solutions based on nanosecond-scale sampling, a sampling 100-times longer than that of conventional QM-based samplings. Furthermore, we have evaluated two dynamic properties, the diffusion coefficient and difference spectra, with high statistical certainty. Furthermore the calculation of these properties has not previously been possible within the conventional QM/MM framework. Based on our analysis, we have quantitatively evaluated the quantum chemical solvation effects, which show distinct differences between the cations.

  19. Self-reduction and size controlled synthesis of silver nanoparticles on carbon nanospheres by grafting triazine-based molecular layer for conductivity improvement

    Science.gov (United States)

    Sang, Jing; Aisawa, Sumio; Hirahara, Hidetoshi; Kudo, Takahiro; Mori, Kunio

    2016-02-01

    A facile, self-reduction and size controlled synthesis method has been explored to fabricate silver nanoparticles (Ag NPs) on carbon nanosphere (CNs) under mild conditions. Without using predeposition of seed metals and reducing agent, a uniform and complete layer of Ag NPs was formed through grafting a molecular layer on CNs surfaces under UV irradiation. The size and thickness of Ag NPs were effectively tuned by adjusting the UV irradiation time. This direct formation of Ag NPs was attributed to self seed in aqueous Ag(NH3)2+ complex solution through a triazine-based silane coupling agent molecular layer, even at 25 °C. Scanning electron microscopy (SEM), Transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS) were employed to characterize the Ag NPs' properties. A substantial conductivity improvement of prepared Ag NPs on carbon nanosphere was demonstrated. The presented method is simple and environmentally friendly and thus should be of significant value for the industrial fabrication of Ag NPs on carbon nanosphere in conduct electricity paint and coating applications.

  20. A model for optimal offspring size in fish, including live-bearing and parental effects.

    Science.gov (United States)

    Jørgensen, Christian; Auer, Sonya K; Reznick, David N

    2011-05-01

    Since Smith and Fretwell's seminal article in 1974 on the optimal offspring size, most theory has assumed a trade-off between offspring number and offspring fitness, where larger offspring have better survival or fitness, but with diminishing returns. In this article, we use two ubiquitous biological mechanisms to derive the shape of this trade-off: the offspring's growth rate combined with its size-dependent mortality (predation). For a large parameter region, we obtain the same sigmoid relationship between offspring size and offspring survival as Smith and Fretwell, but we also identify parameter regions where the optimal offspring size is as small or as large as possible. With increasing growth rate, the optimal offspring size is smaller. We then integrate our model with strategies of parental care. Egg guarding that reduces egg mortality favors smaller or larger offspring, depending on how mortality scales with size. For live-bearers, the survival of offspring to birth is a function of maternal survival; if the mother's survival increases with her size, then the model predicts that larger mothers should produce larger offspring. When using parameters for Trinidadian guppies Poecilia reticulata, differences in both growth and size-dependent predation are required to predict observed differences in offspring size between wild populations from high- and low-predation environments.

  1. Are larger and/or more symmetrical Drosophila melanogaster (Diptera, Drosophilidae males more successful in matings in nature?

    Directory of Open Access Journals (Sweden)

    Sofija Pavković-Lučić

    Full Text Available Are larger and/or more symmetrical Drosophila melanogaster (Diptera, Drosophilidae males more successful in matings in nature? Sexual selection in Drosophila melanogaster, related to body size and fluctuating asymmetry in wing length and number of sex comb teeth in males, was tested in natural conditions. Males collected in copula were significantly larger than those collected as a single, while no difference in mean number of sex comb teeth between copulating and single males was observed. On the other hand, single males had greater asymmetry both for wing length and number of sex comb teeth than their mating counterparts. It looks like that symmetry of these bilateral traits also may play a role in sexual selection in this dipteran species in nature.

  2. Physical Selectivity of Molecularly Imprinted polymers evaluated through free volume size distributions derived from Positron Lifetime Spectroscopy

    Science.gov (United States)

    Pasang, T.; Ranganathaiah, C.

    2015-06-01

    The technique of imprinting molecules of various sizes in a stable structure of polymer matrix has derived multitudes of applications. Once the template molecule is extracted from the polymer matrix, it leaves behind a cavity which is physically (size and shape) and chemically (functional binding site) compatible to the particular template molecule. Positron Annihilation Lifetime Spectroscopy (PALS) is a well known technique to measure cavity sizes precisely in the nanoscale and is not being used in the field of MIPs effectively. This method is capable of measuring nanopores and hence suitable to understand the physical selectivity of the MIPs better. With this idea in mind, we have prepared molecular imprinted polymers (MIPs) with methacrylicacid (MAA) as monomer and EGDMA as cross linker in different molar ratio for three different size template molecules, viz. 4-Chlorophenol (4CP)(2.29 Å), 2-Nephthol (2NP) (3.36 Å) and Phenolphthalein (PP) (4.47Å). FTIR and the dye chemical reactions are used to confirm the complete extraction of the template molecules from the polymer matrix. The free volume size and its distribution have been derived from the measured o-Ps lifetime spectra. Based on the free volume distribution analysis, the percentage of functional cavities for the three template molecules are determined. Percentage of functional binding cavities for 4-CP molecules has been found out to be 70.2% and the rest are native cavities. Similarly for 2NP it is 81.5% and nearly 100% for PP. Therefore, PALS method proves to be very precise and accurate for determining the physical selectivity of MIPs.

  3. Eye Size, Fovea, and Foraging Ecology in Accipitriform Raptors.

    Science.gov (United States)

    Potier, Simon; Mitkus, Mindaugas; Bonadonna, Francesco; Duriez, Olivier; Isard, Pierre-François; Dulaurent, Thomas; Mentek, Marielle; Kelber, Almut

    2017-01-01

    Birds with larger eyes are predicted to have higher spatial resolution because of their larger retinal image. Raptors are well known for their acute vision, mediated by their deep central fovea. Because foraging strategies may demand specific visual adaptations, eye size and fovea may differ between species with different foraging ecology. We tested whether predators (actively hunting mobile prey) and carrion eaters (eating dead prey) from the order Accipitriformes differ in eye size, foveal depth, and retinal thickness using spectral domain optical coherence tomography and comparative phylogenetic methods. We found that (1) all studied predators (except one) had a central and a temporal fovea, but all carrion eaters had only the central fovea; (2) eye size scaled with body mass both in predators and carrion eaters; (3) predators had larger eyes relative to body mass and a thicker retina at the edge of the fovea than carrion eaters, but there was no difference in the depth of the central fovea between the groups. Finally, we found that (4) larger eyes generally had a deeper central fovea. These results suggest that the visual system of raptors within the order Accipitriformes may be highly adapted to the foraging strategy, except for the foveal depth, which seems mostly dependent upon the eye size. © 2017 S. Karger AG, Basel.

  4. Smart moves: effects of relative brain size on establishment success of invasive amphibians and reptiles.

    Science.gov (United States)

    Amiel, Joshua J; Tingley, Reid; Shine, Richard

    2011-04-06

    Brain size relative to body size varies considerably among animals, but the ecological consequences of that variation remain poorly understood. Plausibly, larger brains confer increased behavioural flexibility, and an ability to respond to novel challenges. In keeping with that hypothesis, successful invasive species of birds and mammals that flourish after translocation to a new area tend to have larger brains than do unsuccessful invaders. We found the same pattern in ectothermic terrestrial vertebrates. Brain size relative to body size was larger in species of amphibians and reptiles reported to be successful invaders, compared to species that failed to thrive after translocation to new sites. This pattern was found in six of seven global biogeographic realms; the exception (where relatively larger brains did not facilitate invasion success) was Australasia. Establishment success was also higher in amphibian and reptile families with larger relative brain sizes. Future work could usefully explore whether invasion success is differentially associated with enlargement of specific parts of the brain (as predicted by the functional role of the forebrain in promoting behavioural flexibility), or with a general size increase (suggesting that invasion success is facilitated by enhanced perceptual and motor skills, as well as cognitive ability).

  5. Children's accuracy of portion size estimation using digital food images: effects of interface design and size of image on computer screen.

    Science.gov (United States)

    Baranowski, Tom; Baranowski, Janice C; Watson, Kathleen B; Martin, Shelby; Beltran, Alicia; Islam, Noemi; Dadabhoy, Hafza; Adame, Su-heyla; Cullen, Karen; Thompson, Debbe; Buday, Richard; Subar, Amy

    2011-03-01

    To test the effect of image size and presence of size cues on the accuracy of portion size estimation by children. Children were randomly assigned to seeing images with or without food size cues (utensils and checked tablecloth) and were presented with sixteen food models (foods commonly eaten by children) in varying portion sizes, one at a time. They estimated each food model's portion size by selecting a digital food image. The same food images were presented in two ways: (i) as small, graduated portion size images all on one screen or (ii) by scrolling across large, graduated portion size images, one per sequential screen. Laboratory-based with computer and food models. Volunteer multi-ethnic sample of 120 children, equally distributed by gender and ages (8 to 13 years) in 2008-2009. Average percentage of correctly classified foods was 60·3 %. There were no differences in accuracy by any design factor or demographic characteristic. Multiple small pictures on the screen at once took half the time to estimate portion size compared with scrolling through large pictures. Larger pictures had more overestimation of size. Multiple images of successively larger portion sizes of a food on one computer screen facilitated quicker portion size responses with no decrease in accuracy. This is the method of choice for portion size estimation on a computer.

  6. The correlation between supermarket size and national obesity prevalence.

    Science.gov (United States)

    Cameron, Adrian J; Waterlander, Wilma E; Svastisalee, Chalida M

    2014-01-01

    Supermarkets provide healthy and affordable food options while simultaneously heavily promoting energy-dense, nutrient-poor foods and drinks. Store size may impact body weight via multiple mechanisms. Large stores encourage purchasing of more food in a single visit, and in larger packages. In addition they provide greater product choice (usually at lower prices) and allow greater exposure to foods of all types. These characteristics may promote purchasing and consumption. Our objective was to assess the relationship between supermarket size and obesity, which has rarely been assessed. Data on supermarket size (measured as total aisle length in metres) was from 170 stores in eight developed countries with Western-style diets. Data for national obesity prevalence was obtained from the UK National Obesity Observatory. We found a strong correlation between average store size and national obesity prevalence (r = 0.96). Explanations for the association between store size and national obesity prevalence may include larger and less frequent shopping trips and greater choice and exposure to foods in countries with larger stores. Large supermarkets may represent a food system that focuses on quantity ahead of quality and therefore may be an important and novel environmental indicator of a pattern of behaviour that encourages obesity.

  7. Size-fractionated dissolved primary production and carbohydrate composition of the coccolithophore Emiliania huxleyi

    Science.gov (United States)

    Borchard, C.; Engel, A.

    2015-02-01

    Extracellular release (ER) by phytoplankton is the major source of fresh dissolved organic carbon (DOC) in marine ecosystems and accompanies primary production during all growth phases. Little is known, so far, on size and composition of released molecules, and to which extent ER occurs passively, by leakage, or actively, by exudation. Here, we report on ER by the widespread and bloom-forming coccolithophore Emiliania huxleyi grown under steady-state conditions in phosphorus-controlled chemostats (N:P = 29, growth rate of μ = 0.2 d-1) at present-day and high-CO2 concentrations. 14C incubations were performed to determine primary production (PP), comprised of particulate (PO14C) and dissolved organic carbon (DO14C). Concentration and composition of particulate combined carbohydrates (pCCHO) and high-molecular-weight (>1 kDa, HMW) dissolved combined carbohydrates (dCCHO) were determined by ion chromatography. Information on size distribution of ER products was obtained by investigating distinct size classes (10 kDa was significantly different, with a higher mol% of arabinose. The mol% of acidic sugars increased and that of glucose decreased with increasing size of HMW-dCCHO. We conclude that larger polysaccharides follow different production and release pathways than smaller molecules, potentially serving distinct ecological and biogeochemical functions.

  8. Imaging samples larger than the field of view: the SLS experience

    Science.gov (United States)

    Vogiatzis Oikonomidis, Ioannis; Lovric, Goran; Cremona, Tiziana P.; Arcadu, Filippo; Patera, Alessandra; Schittny, Johannes C.; Stampanoni, Marco

    2017-06-01

    Volumetric datasets with micrometer spatial and sub-second temporal resolutions are nowadays routinely acquired using synchrotron X-ray tomographic microscopy (SRXTM). Although SRXTM technology allows the examination of multiple samples with short scan times, many specimens are larger than the field-of-view (FOV) provided by the detector. The extension of the FOV in the direction perpendicular to the rotation axis remains non-trivial. We present a method that can efficiently increase the FOV merging volumetric datasets obtained by region-of-interest tomographies in different 3D positions of the sample with a minimal amount of artefacts and with the ability to handle large amounts of data. The method has been successfully applied for the three-dimensional imaging of a small number of mouse lung acini of intact animals, where pixel sizes down to the micrometer range and short exposure times are required.

  9. Effect of Grain Size on Differential Desorption of Volatile Species and on Non-ideal MHD Diffusivity

    Science.gov (United States)

    Zhao, Bo; Caselli, Paola; Li, Zhi-Yun

    2018-05-01

    We developed a chemical network for modeling the chemistry and non-ideal MHD effects from the collapsing dense molecular clouds to protostellar disks. First, we re-formulated the cosmic-ray desorption rate by considering the variations of desorption rate over the grain size distribution. We find that the differential desorption of volatile species is amplified by the grains larger than 0.1 μm, because larger grains are heated to a lower temperature by cosmic-rays and hence more sensitive to the variations in binding energies. As a result, atomic nitrogen N is ˜2 orders of magnitude more abundant than CO; N2H+ also becomes a few times more abundant than HCO+ due to the increased gas-phase N2. However, the changes in ionization fraction due to freeze-out and desorption only have minor effects on the non-ideal MHD diffusivities. Our chemical network confirms that the very small grains (VSGs: below a few 100 Å) weakens the efficiency of both ambipolar diffusion and Hall effect. In collapsing dense cores, a maximum ambipolar diffusion is achieved when truncating the MRN size distribution at 0.1 μm, and for a maximum Hall effect, the truncation occurs at 0.04 μm. We conclude that the grain size distribution is crucial to the differential depletion between CO and N2 related molecules, as well as to the non-ideal MHD diffusivities in dense cores.

  10. Do class size effects differ across grades?

    DEFF Research Database (Denmark)

    Nandrup, Anne Brink

    size cap that creates exogenous variation in class sizes. Significant (albeit modest) negative effects of class size increases are found for children on primary school levels. The effects on math abilities are statistically different across primary and secondary school. Larger classes do not affect......This paper contributes to the class size literature by analyzing whether short-run class size effects are constant across grade levels in compulsory school. Results are based on administrative data on all pupils enroled in Danish public schools. Identification is based on a government-imposed class...

  11. The effect of alcohols on red blood cell mechanical properties and membrane fluidity depends on their molecular size.

    Science.gov (United States)

    Sonmez, Melda; Ince, Huseyin Yavuz; Yalcin, Ozlem; Ajdžanović, Vladimir; Spasojević, Ivan; Meiselman, Herbert J; Baskurt, Oguz K

    2013-01-01

    The role of membrane fluidity in determining red blood cell (RBC) deformability has been suggested by a number of studies. The present investigation evaluated alterations of RBC membrane fluidity, deformability and stability in the presence of four linear alcohols (methanol, ethanol, propanol and butanol) using ektacytometry and electron paramagnetic resonance (EPR) spectroscopy. All alcohols had a biphasic effect on deformability such that it increased then decreased with increasing concentration; the critical concentration for reversal was an inverse function of molecular size. EPR results showed biphasic changes of near-surface fluidity (i.e., increase then decrease) and a decreased fluidity of the lipid core; rank order of effectiveness was butanol > propanol > ethanol > methanol, with a significant correlation between near-surface fluidity and deformability (r = 0.697; palcohol enhanced the impairment of RBC deformability caused by subjecting cells to 100 Pa shear stress for 300 s, with significant differences from control being observed at higher concentrations of all four alcohols. The level of hemolysis was dependent on molecular size and concentration, whereas echinocytic shape transformation (i.e., biconcave disc to crenated morphology) was observed only for ethanol and propanol. These results are in accordance with available data obtained on model membranes. They document the presence of mechanical links between RBC deformability and near-surface membrane fluidity, chain length-dependence of the ability of alcohols to alter RBC mechanical behavior, and the biphasic response of RBC deformability and near-surface membrane fluidity to increasing alcohol concentrations.

  12. Country size, currency unions, and international asset returns

    OpenAIRE

    Hassan, Tarek A.

    2015-01-01

    The fact that economies differ in size has important implications for international asset returns. I solve for the spread on international bonds and stocks in an endowment economy with complete asset markets and non-traded goods. The model predicts that larger countries have lower real interest rates because their bonds provide insurance against shocks that affect a larger fraction of the world economy. Larger countries' bonds must therefore pay lower excess returns in equilibrium and uncover...

  13. Smart Moves: Effects of Relative Brain Size on Establishment Success of Invasive Amphibians and Reptiles

    Science.gov (United States)

    Amiel, Joshua J.; Tingley, Reid; Shine, Richard

    2011-01-01

    Brain size relative to body size varies considerably among animals, but the ecological consequences of that variation remain poorly understood. Plausibly, larger brains confer increased behavioural flexibility, and an ability to respond to novel challenges. In keeping with that hypothesis, successful invasive species of birds and mammals that flourish after translocation to a new area tend to have larger brains than do unsuccessful invaders. We found the same pattern in ectothermic terrestrial vertebrates. Brain size relative to body size was larger in species of amphibians and reptiles reported to be successful invaders, compared to species that failed to thrive after translocation to new sites. This pattern was found in six of seven global biogeographic realms; the exception (where relatively larger brains did not facilitate invasion success) was Australasia. Establishment success was also higher in amphibian and reptile families with larger relative brain sizes. Future work could usefully explore whether invasion success is differentially associated with enlargement of specific parts of the brain (as predicted by the functional role of the forebrain in promoting behavioural flexibility), or with a general size increase (suggesting that invasion success is facilitated by enhanced perceptual and motor skills, as well as cognitive ability). PMID:21494328

  14. Smart moves: effects of relative brain size on establishment success of invasive amphibians and reptiles.

    Directory of Open Access Journals (Sweden)

    Joshua J Amiel

    2011-04-01

    Full Text Available Brain size relative to body size varies considerably among animals, but the ecological consequences of that variation remain poorly understood. Plausibly, larger brains confer increased behavioural flexibility, and an ability to respond to novel challenges. In keeping with that hypothesis, successful invasive species of birds and mammals that flourish after translocation to a new area tend to have larger brains than do unsuccessful invaders. We found the same pattern in ectothermic terrestrial vertebrates. Brain size relative to body size was larger in species of amphibians and reptiles reported to be successful invaders, compared to species that failed to thrive after translocation to new sites. This pattern was found in six of seven global biogeographic realms; the exception (where relatively larger brains did not facilitate invasion success was Australasia. Establishment success was also higher in amphibian and reptile families with larger relative brain sizes. Future work could usefully explore whether invasion success is differentially associated with enlargement of specific parts of the brain (as predicted by the functional role of the forebrain in promoting behavioural flexibility, or with a general size increase (suggesting that invasion success is facilitated by enhanced perceptual and motor skills, as well as cognitive ability.

  15. Promotion of alternative-sized personal protective equipment.

    Science.gov (United States)

    Flynn, Michael A; Keller, Brenna; DeLaney, Sheli C

    2017-12-01

    With more diversity in the workforce, companies are producing PPE such as hard hats, safety glasses, coveralls, foot protection, and safety harnesses for a larger range of body shapes and sizes. However, gray literature reports suggest that barriers exist to getting alternate sized PPE from the manufacturer to the workers who need it. The purpose of this study is to determine the extent to which alternative-sized PPE is marketed. A web-based review of seven major manufacturers of PPE was conducted to determine: (a) whether or not they offer alternative-sized products, (b) if these products are clearly labeled, and (c) if images used to display PPE are representative of a diverse workforce. Of the seven PPE manufacturers investigated, six had at least one product that was marketed as gender and/or size alternatives however, alternative sizes were more common for larger body types. Alternative-sized products rarely included size charts, and the models used to display PPE were overwhelmingly white males of average size. Despite the growing availability of alternative-sized PPE, it can be difficult to find these products, which suggests that they are rarely promoted or labeled as alternative-sized. Our study indicates that companies should expand their product lines and more aggressively market and promote these items. Guidance on how to properly fit their products would also be extremely helpful to the end-user. Manufacturers could improve the availability of alternative-sized PPE and increase their promotion of these products on their websites and in their catalogs. Individual companies and safety professionals may assist in this process by demonstrating demand for alternative-sized PPE. Published by Elsevier Ltd.

  16. Size determinations of colloidal fat emulsions

    DEFF Research Database (Denmark)

    Kuntsche, Judith; Klaus, Katrin; Steiniger, Frank

    2009-01-01

    Size and size distributions of colloidal dispersions are of crucial importance for their performance and safety. In the present study, commercially available fat emulsions (Lipofundin N, Lipofundin MCT and Lipidem) were analyzed by photon correlation spectroscopy, laser diffraction with adequate...... was checked with mixtures of monodisperse polystyrene nanospheres. In addition, the ultrastructure of Lipofundin N and Lipofundin MCT was investigated by cryo-electron microscopy. All different particle sizing methods gave different mean sizes and size distributions but overall, results were in reasonable...... agreement. By all methods, a larger mean droplet size (between 350 and 400 nm) as well as a broader distribution was measured for Lipofundin N compared to Lipofundin MCT and Lipidem (mean droplet size between about 280 and 320 nm). Size distributions of Lipofundin MCT and Lipidem were very similar...

  17. Diffusion of two-dimensional epitaxial clusters on metal (100) surfaces: Facile versus nucleation-mediated behavior and their merging for larger sizes

    Science.gov (United States)

    Lai, King C.; Liu, Da-Jiang; Evans, James W.

    2017-12-01

    For diffusion of two-dimensional homoepitaxial clusters of N atoms on metal (100) surfaces mediated by edge atom hopping, macroscale continuum theory suggests that the diffusion coefficient scales like DN˜ N-β with β =3 /2 . However, we find quite different and diverse behavior in multiple size regimes. These include: (i) facile diffusion for small sizes N mediated diffusion with small β 2 for N =Np+1 and Np+2 also for moderate sizes 9 ≤N ≤O (102) ; (iv) merging of the above distinct branches and subsequent anomalous scaling with 1 ≲β analysis must account for a strong enhancement of diffusivity for short time increments due to back correlation in the cluster motion. Further understanding of this enhancement, of anomalous size scaling behavior, and of the merging of various branches, is facilitated by combinatorial analysis of the number of the ground-state and low-lying excited state cluster configurations, and also of kink populations.

  18. Size-dependent melting modes and behaviors of Ag nanoparticles: a molecular dynamics study

    Science.gov (United States)

    Liang, Tianshou; Zhou, Dejian; Wu, Zhaohua; Shi, Pengpeng

    2017-12-01

    The size-dependent melting behaviors and mechanisms of Ag nanoparticles (NPs) with diameters of 3.5-16 nm were investigated by molecular dynamics (MD). Two distinct melting modes, non-premelting and premelting with transition ranges of about 7-8 nm, for Ag NPs were demonstrated via the evolution of distribution and transition of atomic physical states during annealing. The small Ag NPs (3.5-7 nm) melt abruptly without a stable liquid shell before the melting point, which is characterized as non-premelting. A solid-solid crystal transformation is conducted through the migration of adatoms on the surface of Ag NPs with diameters of 3.5-6 nm before the initial melting, which is mainly responsible for slightly increasing the melting point of Ag NPs. On the other hand, surface premelting of Ag NPs with diameters of 8-16 nm propagates from the outer shell to the inner core with initial anisotropy and late isotropy as the temperature increases, and the close-packed facets {111} melt by a side-consumed way which is responsible for facets {111} melting in advance relative to the crystallographic plane {111}. Once a stable liquid shell is formed, its size-independent minimum thickness is obtained, and a three-layer structure of atomic physical states is set up. Lastly, the theory of point defect-pair (vacancy-interstitial) severing as the mechanism of formation and movement of the solid-liquid interface was also confirmed. Our study provides a basic understanding and theoretical guidance for the research, production and application of Ag NPs.

  19. Study on Compatibility of Polymer Hydrodynamic Size and Pore Throat Size for Honggang Reservoir

    Directory of Open Access Journals (Sweden)

    Dan-Dan Yin

    2014-01-01

    Full Text Available Long core flow experiment was conducted to study problems like excessive injection pressure and effective lag of oil wells during the polymer flooding in Honggang reservoir in Jilin oilfield. According to the changes in viscosity and hydrodynamic dimensions before and after polymer solution was injected into porous media, the compatibility of polymer hydrodynamic dimension and the pore throat size was studied in this experiment. On the basis of the median of radius R of pore throats in rocks with different permeability, dynamic light scattering method (DLS was adopted to measure the hydrodynamic size Rh of polymer solution with different molecular weights. The results state that three kinds of 1500 mg/L concentration polymer solution with 2000 × 104, 1500 × 104, and 1000 × 104 molecular weight matched well with the pore throat in rocks with permeability of 300 mD, 180 mD, and 75 mD in sequence. In this case, the ratios of core pore throat radius median to the size of polymer molecular clew R/Rh are 6.16, 5.74, and 6.04. For Honggang oil reservoir in Jilin, when that ratio ranges from 5.5 to 6.0, the compatibility of polymer and the pore structure will be relatively better.

  20. Defined-size DNA triple crossover construct for molecular electronics: modification, positioning and conductance properties.

    Science.gov (United States)

    Linko, Veikko; Leppiniemi, Jenni; Paasonen, Seppo-Tapio; Hytönen, Vesa P; Toppari, J Jussi

    2011-07-08

    We present a novel, defined-size, small and rigid DNA template, a so-called B-A-B complex, based on DNA triple crossover motifs (TX tiles), which can be utilized in molecular scale patterning for nanoelectronics, plasmonics and sensing applications. The feasibility of the designed construct is demonstrated by functionalizing the TX tiles with one biotin-triethylene glycol (TEG) and efficiently decorating them with streptavidin, and furthermore by positioning and anchoring single thiol-modified B-A-B complexes to certain locations on a chip via dielectrophoretic trapping. Finally, we characterize the conductance properties of the non-functionalized construct, first by measuring DC conductivity and second by utilizing AC impedance spectroscopy in order to describe the conductivity mechanism of a single B-A-B complex using a detailed equivalent circuit model. This analysis also reveals further information about the conductivity of DNA structures in general.

  1. The Small Nuclear Genomes of Selaginella Are Associated with a Low Rate of Genome Size Evolution.

    Science.gov (United States)

    Baniaga, Anthony E; Arrigo, Nils; Barker, Michael S

    2016-06-03

    The haploid nuclear genome size (1C DNA) of vascular land plants varies over several orders of magnitude. Much of this observed diversity in genome size is due to the proliferation and deletion of transposable elements. To date, all vascular land plant lineages with extremely small nuclear genomes represent recently derived states, having ancestors with much larger genome sizes. The Selaginellaceae represent an ancient lineage with extremely small genomes. It is unclear how small nuclear genomes evolved in Selaginella We compared the rates of nuclear genome size evolution in Selaginella and major vascular plant clades in a comparative phylogenetic framework. For the analyses, we collected 29 new flow cytometry estimates of haploid genome size in Selaginella to augment publicly available data. Selaginella possess some of the smallest known haploid nuclear genome sizes, as well as the lowest rate of genome size evolution observed across all vascular land plants included in our analyses. Additionally, our analyses provide strong support for a history of haploid nuclear genome size stasis in Selaginella Our results indicate that Selaginella, similar to other early diverging lineages of vascular land plants, has relatively low rates of genome size evolution. Further, our analyses highlight that a rapid transition to a small genome size is only one route to an extremely small genome. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  2. Sauropod dinosaurs evolved moderately sized genomes unrelated to body size.

    Science.gov (United States)

    Organ, Chris L; Brusatte, Stephen L; Stein, Koen

    2009-12-22

    Sauropodomorph dinosaurs include the largest land animals to have ever lived, some reaching up to 10 times the mass of an African elephant. Despite their status defining the upper range for body size in land animals, it remains unknown whether sauropodomorphs evolved larger-sized genomes than non-avian theropods, their sister taxon, or whether a relationship exists between genome size and body size in dinosaurs, two questions critical for understanding broad patterns of genome evolution in dinosaurs. Here we report inferences of genome size for 10 sauropodomorph taxa. The estimates are derived from a Bayesian phylogenetic generalized least squares approach that generates posterior distributions of regression models relating genome size to osteocyte lacunae volume in extant tetrapods. We estimate that the average genome size of sauropodomorphs was 2.02 pg (range of species means: 1.77-2.21 pg), a value in the upper range of extant birds (mean = 1.42 pg, range: 0.97-2.16 pg) and near the average for extant non-avian reptiles (mean = 2.24 pg, range: 1.05-5.44 pg). The results suggest that the variation in size and architecture of genomes in extinct dinosaurs was lower than the variation found in mammals. A substantial difference in genome size separates the two major clades within dinosaurs, Ornithischia (large genomes) and Saurischia (moderate to small genomes). We find no relationship between body size and estimated genome size in extinct dinosaurs, which suggests that neutral forces did not dominate the evolution of genome size in this group.

  3. Ultrahigh Molecular Weight Linear Block Copolymers: Rapid Access by Reversible-Deactivation Radical Polymerization and Self- Assembly into Large Domain Nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Mapas, Jose Kenneth D.; Thomay, Tim; Cartwright, Alexander N.; Ilavsky, Jan; Rzayev, Javid

    2016-05-05

    Block copolymer (BCP) derived periodic nanostructures with domain sizes larger than 150 nm present a versatile platform for the fabrication of photonic materials. So far, the access to such materials has been limited to highly synthetically involved protocols. Herein, we report a simple, “user-friendly” method for the preparation of ultrahigh molecular weight linear poly(solketal methacrylate-b-styrene) block copolymers by a combination of Cu-wire-mediated ATRP and RAFT polymerizations. The synthesized copolymers with molecular weights up to 1.6 million g/mol and moderate dispersities readily assemble into highly ordered cylindrical or lamella microstructures with domain sizes as large as 292 nm, as determined by ultra-small-angle x-ray scattering and scanning electron microscopy analyses. Solvent cast films of the synthesized block copolymers exhibit stop bands in the visible spectrum correlated to their domain spacings. The described method opens new avenues for facilitated fabrication and the advancement of fundamental understanding of BCP-derived photonic nanomaterials for a variety of applications.

  4. Quantitative analysis of CTEM images of small dislocation loops in Al and stacking fault tetrahedra in Cu generated by molecular dynamics simulation

    International Nuclear Information System (INIS)

    Schaeublin, R.; Almazouzi, A.; Dai, Y.; Osetsky, Yu.N.; Victoria, M.

    2000-01-01

    The visibility of conventional transmission electron microscopy (CTEM) images of small crystalline defects generated by molecular dynamics (MD) simulation is investigated. Faulted interstitial dislocation loops in Al smaller than 2 nm in diameter and stacking fault tetrahedra (SFT) in Cu smaller than 4 nm in side are assessed. A recent approach allowing to simulate the CTEM images of computer generated samples described by their atomic positions is applied to obtain bright field and weak beam images. For the dislocation loop-like cluster it appears that the simulated image is comparable to experimental images. The contrast of the g(3.1g) near weak beam image decreases with decreasing size of the cluster but is still 20% of the background intensity for a 2 interstitial cluster. This indicates a visibility at the limit of the experimental background noise. In addition, the cluster image size, which is here always larger than the real size, saturates at about 1 nm when the cluster real size decreases below 1 nm, which corresponds to a cluster of 8 interstitials. For the SFT in Cu the g(6.1g) weak beam image is comparable to experimental images. It appears that the image size is larger than the real size by 20%. A large loss of the contrast features that allows to identify an SFT is observed on the image of the smallest SFT (21 vacancies)

  5. Spatially Extended and High-Velocity Dispersion Molecular Component in Spiral Galaxies: Single-Dish Versus Interferometric Observations

    Science.gov (United States)

    Caldú-Primo, Anahi; Schruba, Andreas; Walter, Fabian; Leroy, Adam; Bolatto, Alberto D.; Vogel, Stuart

    2015-02-01

    Recent studies of the molecular medium in nearby galaxies have provided mounting evidence that the molecular gas can exist in two phases: one that is clumpy and organized as molecular clouds and another one that is more diffuse. This last component has a higher velocity dispersion than the clumpy one. In order to investigate these two molecular components further, we compare the fluxes and line widths of CO in NGC 4736 and NGC 5055, two nearby spiral galaxies for which high-quality interferometric as well as single-dish data sets are available. Our analysis leads to two main results: (1) employing three different methods, we determine the flux recovery of the interferometer as compared to the single-dish to be within a range of 35%-74% for NGC 4736 and 81%-92% for NGC 5055, and (2) when focusing on high (S/N ≥ 5) lines of sight (LOSs), the single-dish line widths are larger by ˜(40 ± 20)% than the ones derived from interferometric data, which is in agreement with stacking all LOSs. These results point to a molecular gas component that is distributed over spatial scales larger than 30″(˜1 kpc), and is therefore filtered out by the interferometer. The available observations do not allow us to distinguish between a truly diffuse gas morphology and a uniform distribution of small clouds that are separated by less than the synthesized beam size (˜3″ or ˜100 pc), as they would both be invisible for the interferometer. This high velocity dispersion component has a dispersion similar to what is found in the atomic medium, as traced through observations of the H i line.

  6. Size exclusion chromatography for semipreparative scale separation of Au38(SR)24 and Au40(SR)24 and larger clusters.

    Science.gov (United States)

    Knoppe, Stefan; Boudon, Julien; Dolamic, Igor; Dass, Amala; Bürgi, Thomas

    2011-07-01

    Size exclusion chromatography (SEC) on a semipreparative scale (10 mg and more) was used to size-select ultrasmall gold nanoclusters (<2 nm) from polydisperse mixtures. In particular, the ubiquitous byproducts of the etching process toward Au(38)(SR)(24) (SR, thiolate) clusters were separated and gained in high monodispersity (based on mass spectrometry). The isolated fractions were characterized by UV-vis spectroscopy, MALDI mass spectrometry, HPLC, and electron microscopy. Most notably, the separation of Au(38)(SR)(24) and Au(40)(SR)(24) clusters is demonstrated.

  7. Larger fig wasps are more careful about which figs to enter--with good reason.

    Science.gov (United States)

    Liu, Cong; Yang, Da-Rong; Compton, Stephen G; Peng, Yan-Qiong

    2013-01-01

    Floral longevity reflects a balance between gains in pollinator visitation and the costs of flower maintenance. Because rewards to pollinators change over time, older flowers may be less attractive, reducing the value of extended longevity. Un-pollinated figs, the inflorescences of Ficus species, can remain receptive for long periods, but figs that are older when entered by their host-specific fig wasp pollinators produce fewer seeds and fig wasp offspring. Our field experiments with Ficushispida, a dioecious fig tree, examined how the length of time that receptive figs have remained un-pollinated influences the behaviour and reproductive success of its short-lived fig wasp pollinator, Ceratosolensolmsi marchali. The results were consistent in three different seasons, and on male and female trees, although receptivity was greatly extended during colder months. Pollinators took longer to find the ostioles of older figs, and longer to penetrate them. They also became increasingly unwilling to enter figs as they aged, and increasing numbers of the wasps became trapped in the ostiolar bracts. Larger individuals were particularly unwilling to enter older figs, resulting in older figs being pollinated by smaller wasps. On female trees, where figs produce only seeds, seed production declined rapidly with fig age. On male trees, the numbers and size of fig wasp offspring declined, and a higher proportion were male. Older male figs are harder to enter, especially for larger individuals, and offer poorer quality oviposition opportunities. This study opens an interesting new perspective on the coevolution of figs and their pollinators, especially factors influencing pollinator body size and emphasises the subtleties of interactions between mutualists.

  8. Molecular Formula and Molecular Weight - NBDC NikkajiRDF | LSDB Archive [Life Science Database Archive metadata

    Lifescience Database Archive (English)

    Full Text Available List Contact us NBDC NikkajiRDF Molecular Formula and Molecular Weight Data detail Data name Molecular Formula and Molecul...- Description of data contents This RDF data includes molecular formula and molecular weight of chemical sub...ikkajiRDF_MFMW.tar.gz File size: 404 MB Simple search URL - Data acquisition method The data was converted from data of molecul...ar formulas and molecular weights in Basic Information ( http://dbarchive.biosciencedbc.j... Policy | Contact Us Molecular Formula and Molecular Weight - NBDC NikkajiRDF | LSDB Archive ...

  9. Size-dependent magnetic properties of branchlike nickel oxide nanocrystals

    Directory of Open Access Journals (Sweden)

    Dan Liu

    2017-01-01

    Full Text Available Branchlike nickel oxide nanocrystals with narrow size distribution are obtained by a solution growth method. The size-dependent of magnetic properties of the nickel oxides were investigated. The results of magnetic characterization indicate that the NiO nanocrystals with size below 12.8 nm show very weak ferromagnetic state at room temperature due to the uncompensated spins. Both of the average blocking temperature (Tb and the irreversible temperature (Tirr increase with the increase of nanoparticle sizes, while both the remnant magnetization and the coercivity at 300 K increase with the decrease of the particle sizes. Moreover, the disappearance of two-magnon (2M band and redshift of one-phonon longitudinal (1LO and two-phonon LO in vibrational properties due to size reduction are observed. Compared to the one with the spherical morphological, it is also found that nano-structured nickel oxides with the branchlike morphology have larger remnant magnetization and the coercivity at 5 K due to their larger surface-to-volume ratio and greater degree of broken symmetry at the surface or the higher proportion of broken bonds.

  10. Molecularly Imprinted Polymers: Thermodynamic and Kinetic Considerations on the Specific Sorption and Molecular Recognition

    Directory of Open Access Journals (Sweden)

    Kejun Tong

    2008-04-01

    Full Text Available This article presents a work aiming at thermodynamically and kinetically interpreting the specific sorption and recognition by a molecularly imprinted polymer. Using Boc-L-Phe-OH as a template, the imprinted material was prepared. The result indicates that the prepared polymer can well discriminate the imprint species from its analogue (Boc-D-Phe-OH, so as to adsorb more for the former but less for the latter. Kinetic analysis indicates that this specific sorption, in nature, can be a result of a preferential promotion. The imprint within the polymer causes a larger adsorption rate for the template than for the analogue. Thermodynamic study also implies that the molecular induction from the specific imprint to the template is larger than to the analogue, which thus makes the polymer capable of preferentially alluring the template to bind.

  11. Sizing of intergranular stress corrosion cracking using low frequency ultrasound

    International Nuclear Information System (INIS)

    Fuller, M.D.; Avioli, M.J.; Rose, J.L.

    1985-01-01

    Based upon the work thus far accomplished on low frequency sizing, the following conclusions can be drawn: the potential of low frequency ultrasound for the sizing of IGSCC seams encouraging as demonstrated in this work. If minimal walking is expected, larger values of crack height/wavelength ratios should not affect the reliability of estimates; notch data points out the validity of signal amplitude for sizing. With care in frequency consideration, the technique can be extended to cracks; when wavelength is greater than flaw size, importance of orientation and reflector shape diminishes although less so for deeper cracks; when beam profile is larger than the defect size, echo amplitude is proportional to defect area when using shear wave probes and corner reflectors; other factors, in addition to crack size, affect signal amplitude. Reference data to compensate for depth and material (HAZ) is a must; additional crack samples should be studied in order to further develop and characterize the use of low frequency ultrasonics

  12. Understanding the role of pore size homogeneity in the water transport through graphene layers

    Science.gov (United States)

    Su, Jiaye; Zhao, Yunzhen; Fang, Chang

    2018-06-01

    Graphene is a versatile 2D material and attracts an increasing amount of attention from a broad scientific community, including novel nanofluidic devices. In this work, we use molecular dynamics simulations to study the pressure driven water transport through graphene layers, focusing on the pore size homogeneity, realized by the arrangement of two pore sizes. For a given layer number, we find that water flux exhibits an excellent linear behavior with pressure, in agreement with the prediction of the Hagen–Poiseuille equation. Interestingly, the flux for concentrated pore size distribution is around two times larger than that of a uniform distribution. More surprisingly, under a given pressure, the water flux changes in an opposite way for these two distributions, where the flux ratio almost increases linearly with the layer number. For the largest layer number, more distributions suggest the same conclusion that higher water flux can be attained for more concentrated pore size distributions. Similar differences for the water translocation time and occupancy are also identified. The major reason for these results should clearly be due to the hydrogen bond and density profile distributions. Our results are helpful to delineate the exquisite role of pore size homogeneity, and should have great implications for the design of high flux nanofluidic devices and inversely the detection of pore structures.

  13. Stable Size Distribution of Amyloid Plaques Over the Course of Alzheimer Disease

    Science.gov (United States)

    Serrano-Pozo, Alberto; Mielke, Matthew L.; Muzitansky, Alona; Gómez-Isla, Teresa; Growdon, John H.; Bacskai, Brian J.; Betensky, Rebecca A.; Frosch, Matthew P.; Hyman, Bradley T.

    2012-01-01

    Amyloid-β plaques are a key pathological feature of Alzheimer disease (AD), but whether plaque sizes increase or stabilize over the course of AD is unknown. We measured the size distribution of total immunoreactive (10D5-positive) and dense-core (Thioflavine-S-positive) plaques in the temporal neocortex of a large group of AD and plaque-bearing age-matched non-demented subjects to test the hypothesis that amyloid plaques continue to grow along with the progression of the disease. The size of amyloid-β (10D5)-positive plaques did not differ between groups whereas dense-core plaques from the AD group were slightly larger than those in the non-demented group (~25%–30%, p = 0.01). Within the AD group, dense-core plaque size did not independently correlate with duration of clinical disease (from 4 to 21 years, p = 0.68), whereas 10D5-positive plaque size correlated negatively with disease duration (p = 0.01). By contrast, an earlier age of symptom onset strongly predicted a larger postmortem plaque size; this effect was independent of disease duration and the presence of the APOEε4 allele (p = 0.0001). We conclude that plaques vary in size among patients, with larger size distributions correlating with an earlier age of onset, but plaques do not substantially increase in size over the clinical course of the disease. PMID:22805771

  14. Effects of habitat features on size-biased predation on salmon by bears.

    Science.gov (United States)

    Andersson, Luke C; Reynolds, John D

    2017-05-01

    Predators can drive trait divergence among populations of prey by imposing differential selection on prey traits. Habitat characteristics can mediate predator selectivity by providing refuge for prey. We quantified the effects of stream characteristics on biases in the sizes of spawning salmon caught by bears (Ursus arctos and U. americanus) on the central coast of British Columbia, Canada by measuring size-biased predation on spawning chum (Oncorhynchus keta) and pink (O. gorbuscha) salmon in 12 streams with varying habitat characteristics. We tested the hypotheses that bears would catch larger than average salmon (size-biased predation) and that this bias toward larger fish would be higher in streams that provide less protection to spawning salmon from predation (e.g., less pools, wood, undercut banks). We then we tested for how such size biases in turn translate into differences among populations in the sizes of the fish. Bears caught larger-than-average salmon as the spawning season progressed and as predicted, this was most pronounced in streams with fewer refugia for the fish (i.e., wood and undercut banks). Salmon were marginally smaller in streams with more pronounced size-biased predation but this predictor was less reliable than physical characteristics of streams, with larger fish in wider, deeper streams. These results support the hypothesis that selective forces imposed by predators can be mediated by habitat characteristics, with potential consequences for physical traits of prey.

  15. The effect of alcohols on red blood cell mechanical properties and membrane fluidity depends on their molecular size.

    Directory of Open Access Journals (Sweden)

    Melda Sonmez

    Full Text Available The role of membrane fluidity in determining red blood cell (RBC deformability has been suggested by a number of studies. The present investigation evaluated alterations of RBC membrane fluidity, deformability and stability in the presence of four linear alcohols (methanol, ethanol, propanol and butanol using ektacytometry and electron paramagnetic resonance (EPR spectroscopy. All alcohols had a biphasic effect on deformability such that it increased then decreased with increasing concentration; the critical concentration for reversal was an inverse function of molecular size. EPR results showed biphasic changes of near-surface fluidity (i.e., increase then decrease and a decreased fluidity of the lipid core; rank order of effectiveness was butanol > propanol > ethanol > methanol, with a significant correlation between near-surface fluidity and deformability (r = 0.697; p<0.01. The presence of alcohol enhanced the impairment of RBC deformability caused by subjecting cells to 100 Pa shear stress for 300 s, with significant differences from control being observed at higher concentrations of all four alcohols. The level of hemolysis was dependent on molecular size and concentration, whereas echinocytic shape transformation (i.e., biconcave disc to crenated morphology was observed only for ethanol and propanol. These results are in accordance with available data obtained on model membranes. They document the presence of mechanical links between RBC deformability and near-surface membrane fluidity, chain length-dependence of the ability of alcohols to alter RBC mechanical behavior, and the biphasic response of RBC deformability and near-surface membrane fluidity to increasing alcohol concentrations.

  16. Controlling the Molecular Weight of Lignosulfonates by an Alkaline Oxidative Treatment at Moderate Temperatures and Atmospheric Pressure: A Size-Exclusion and Reverse-Phase Chromatography Study

    Directory of Open Access Journals (Sweden)

    Chamseddine Guizani

    2017-11-01

    Full Text Available The molecular weights of lignosulfonates (LSs are modified by a rather simple process involving an alkaline oxidative treatment at moderate temperatures (70–90 °C and atmospheric pressure. Starting from LSs with an average molecular weight of 90,000 Da, and using such a treatment, one can prepare controlled molecular weight LSs in the range of 30,000 to 3500 Da based on the average mass molecular weight. The LS depolymerisation was monitored via reverse-phase and size-exclusion chromatography. It has been shown that the combination of O2, H2O2 and Cu as a catalyst in alkaline conditions at 80 °C induces a high LS depolymerisation. The depolymerisation was systemically accompanied by a vanillin production, the yields of which reached 1.4 wt % (weight percentage on LS raw basis in such conditions. Also, the average molecular weight and vanillin concentration were correlated and depended linearly on the temperature and reaction duration.

  17. Effects of incident cluster size, substrate temperature, and incident energy on bombardment of Ni clusters onto Cu (0 0 1) surface studied using molecular dynamics simulation

    International Nuclear Information System (INIS)

    Lin, Shiang-Jiun; Wu, Cheng-Da; Fang, Te-Hua; Chen, Guan-Hung

    2012-01-01

    The bombardment process of a Ni cluster onto a Cu (0 0 1) surface is studied using molecular dynamics (MD) simulations based on the tight-binding second-moment approximation (TB-SMA) many-body potential. The effects of incident cluster size, substrate temperature, and incident energy are evaluated in terms of molecular trajectories, kinetic energy, stress, self-diffusion coefficient, and sputtering yield. The simulation results clearly show that the penetration depth and Cu surface damage increase with increasing incident cluster size for a given incident energy per atom. The self-diffusion coefficient and the penetration depth of a cluster significantly increase with increasing substrate temperature. An incident cluster can be scattered into molecules or atoms that become embedded in the surface after incidence. When the incident energy is increased, the number of volcano-like defects and the penetration depth increase. A high sputtering yield can be obtained by increasing the incident energy at high temperature. The sputtering yield significantly increases with cluster size when the incident energy is above 5 eV/atom.

  18. Temporal profile of body temperature in acute ischemic stroke: relation to infarct size and outcome.

    Science.gov (United States)

    Geurts, Marjolein; Scheijmans, Féline E V; van Seeters, Tom; Biessels, Geert J; Kappelle, L Jaap; Velthuis, Birgitta K; van der Worp, H Bart

    2016-11-21

    High body temperatures after ischemic stroke have been associated with larger infarct size, but the temporal profile of this relation is unknown. We assess the relation between temporal profile of body temperature and infarct size and functional outcome in patients with acute ischemic stroke. In 419 patients with acute ischemic stroke we assessed the relation between body temperature on admission and during the first 3 days with both infarct size and functional outcome. Infarct size was measured in milliliters on CT or MRI after 3 days. Poor functional outcome was defined as a modified Rankin Scale score ≥3 at 3 months. Body temperature on admission was not associated with infarct size or poor outcome in adjusted analyses. By contrast, each additional 1.0 °C in body temperature on day 1 was associated with 0.31 ml larger infarct size (95% confidence interval (CI) 0.04-0.59), on day 2 with 1.13 ml larger infarct size(95% CI, 0.83-1.43), and on day 3 with 0.80 ml larger infarct size (95% CI, 0.48-1.12), in adjusted linear regression analyses. Higher peak body temperatures on days two and three were also associated with poor outcome (adjusted relative risks per additional 1.0 °C in body temperature, 1.52 (95% CI, 1.17-1.99) and 1.47 (95% CI, 1.22-1.77), respectively). Higher peak body temperatures during the first days after ischemic stroke, rather than on admission, are associated with larger infarct size and poor functional outcome. This suggests that prevention of high temperatures may improve outcome if continued for at least 3 days.

  19. Indoor radon progeny aerosol size measurements in urban, suburban, and rural regions

    International Nuclear Information System (INIS)

    Tu, K.W.; Knutson, E.O.; George, A.C.

    1991-01-01

    By using direct and indirect methods, the authors conducted size distribution measurements of radon progeny particles in a variety of indoor environments in urban, suburban, and rural areas. The radon progeny particle size distribution owing to indoor activities has two definable source categories: (1) gas combustion from stoves and kerosene heaters - particles were found to be smaller than 0.1 μm in diameter, mostly in the range 0.02-0.08 μm; and (2) cigarette smoking and food frying - particles were found to be larger, in the size range 0.1-0.2 μm. The radon progeny particle size distribution, without significant indoor activities, such as cooking, was found to be larger in rural areas than in urban or suburban areas. The modal diameters of the size spectra in the rural areas were two to three times larger than those in urban or suburban areas, around 0.3-0.4 bs. 0.1-0.2 μm. Results obtained by applying the attachment theory to the measured number-weighted size spectra from an electrical aerosol size analyzer support this finding. These results, if confirmed by more extensive studies, will be useful for the assessment of the risk from the inhalation of radon progeny in various indoor environments

  20. Synthesis and electrochemical properties of different sizes of the CuO particles

    International Nuclear Information System (INIS)

    Zhang Xiaojun; Zhang Dongen; Ni Xiaomin; Song Jimei; Zheng Huagui

    2008-01-01

    Well-dispersed cupric oxide (CuO) nanoparticles with the size from 10 to 100 nm were successfully synthesized by thermal decomposition of CuC 2 O 4 precursor at 400 deg. C. The prepared CuO nanoparticles of different sizes used as anode materials for Li ion battery all exhibit high electrochemical capacity at the first discharge. However, with the particles size changing, an interesting phenomenon appears. That is, the larger size of the particles is, the discharge capacity of the first time smaller is, while that of the second time is larger. At the same time, the mechanism of the above phenomenon is discussed in this paper. Surprisingly, we have synthesized the copper nanoparticles with different sizes by the CuO of different sizes as the electrodes

  1. Size-dependent multispectral photoacoustic response of solid and hollow gold nanoparticles

    International Nuclear Information System (INIS)

    Gutrath, Benjamin S; Buchkremer, Anne; Timper, Jan; Leifert, Annika; Simon, Ulrich; Beckmann, Martin F; Schmitz, Georg; Eckert, Thomas; Richtering, Walter

    2012-01-01

    Photoacoustic (PA) imaging attracts a great deal of attention as an innovative modality for longitudinal, non-invasive, functional and molecular imaging in oncology. Gold nanoparticles (AuNPs) are identified as superior, NIR-absorbing PA contrast agents for biomedical applications. Until now, no systematic comparison of the optical extinction and PA efficiency of water-soluble AuNPs of various geometries and small sizes has been performed. Here spherical AuNPs with core diameters of 1.0, 1.4 and 11.2 nm, nanorods with longitudinal/transversal elongation of 38/9 and 44/12 nm and hollow nanospheres with outer/inner diameters of 33/19, 57/30, 68/45 and 85/56 nm were synthesized. The diode laser set-up with excitations at 650, 808, 850 and 905 nm allowed us to correlate the molar PA signal intensity with the molar extinction of the respective AuNPs. Deviations were explained by differences in heat transfer from the particle to the medium and, for larger particles, by the scattering of light. The molar PA intensity of 1.0 nm AuNPs was comparable to the commonly used organic dye methylene blue, and rapidly increased with the lateral size of AuNPs. (paper)

  2. Nano-Sized Cyclodextrin-Based Molecularly Imprinted Polymer Adsorbents for Perfluorinated Compounds—A Mini-Review

    Directory of Open Access Journals (Sweden)

    Abdalla H. Karoyo

    2015-06-01

    Full Text Available Recent efforts have been directed towards the design of efficient and contaminant selective remediation technology for the removal of perfluorinated compounds (PFCs from soils, sediments, and aquatic environments. While there is a general consensus on adsorption-based processes as the most suitable methodology for the removal of PFCs from aquatic environments, challenges exist regarding the optimal materials design of sorbents for selective uptake of PFCs. This article reviews the sorptive uptake of PFCs using cyclodextrin (CD-based polymer adsorbents with nano- to micron-sized structural attributes. The relationship between synthesis of adsorbent materials and their structure relate to the overall sorption properties. Hence, the adsorptive uptake properties of CD-based molecularly imprinted polymers (CD-MIPs are reviewed and compared with conventional MIPs. Further comparison is made with non-imprinted polymers (NIPs that are based on cross-linking of pre-polymer units such as chitosan with epichlorohydrin in the absence of a molecular template. In general, MIPs offer the advantage of selectivity, chemical tunability, high stability and mechanical strength, ease of regeneration, and overall lower cost compared to NIPs. In particular, CD-MIPs offer the added advantage of possessing multiple binding sites with unique physicochemical properties such as tunable surface properties and morphology that may vary considerably. This mini-review provides a rationale for the design of unique polymer adsorbent materials that employ an intrinsic porogen via incorporation of a macrocyclic compound in the polymer framework to afford adsorbent materials with tunable physicochemical properties and unique nanostructure properties.

  3. Nano-Sized Cyclodextrin-Based Molecularly Imprinted Polymer Adsorbents for Perfluorinated Compounds—A Mini-Review

    Science.gov (United States)

    Karoyo, Abdalla H.; Wilson, Lee D.

    2015-01-01

    Recent efforts have been directed towards the design of efficient and contaminant selective remediation technology for the removal of perfluorinated compounds (PFCs) from soils, sediments, and aquatic environments. While there is a general consensus on adsorption-based processes as the most suitable methodology for the removal of PFCs from aquatic environments, challenges exist regarding the optimal materials design of sorbents for selective uptake of PFCs. This article reviews the sorptive uptake of PFCs using cyclodextrin (CD)-based polymer adsorbents with nano- to micron-sized structural attributes. The relationship between synthesis of adsorbent materials and their structure relate to the overall sorption properties. Hence, the adsorptive uptake properties of CD-based molecularly imprinted polymers (CD-MIPs) are reviewed and compared with conventional MIPs. Further comparison is made with non-imprinted polymers (NIPs) that are based on cross-linking of pre-polymer units such as chitosan with epichlorohydrin in the absence of a molecular template. In general, MIPs offer the advantage of selectivity, chemical tunability, high stability and mechanical strength, ease of regeneration, and overall lower cost compared to NIPs. In particular, CD-MIPs offer the added advantage of possessing multiple binding sites with unique physicochemical properties such as tunable surface properties and morphology that may vary considerably. This mini-review provides a rationale for the design of unique polymer adsorbent materials that employ an intrinsic porogen via incorporation of a macrocyclic compound in the polymer framework to afford adsorbent materials with tunable physicochemical properties and unique nanostructure properties. PMID:28347047

  4. Intravascular near-infrared fluorescence molecular imaging of atherosclerosis: toward coronary arterial visualization of biologically high-risk plaques

    Science.gov (United States)

    Calfon, Marcella A.; Vinegoni, Claudio; Ntziachristos, Vasilis; Jaffer, Farouc A.

    2010-01-01

    New imaging methods are urgently needed to identify high-risk atherosclerotic lesions prior to the onset of myocardial infarction, stroke, and ischemic limbs. Molecular imaging offers a new approach to visualize key biological features that characterize high-risk plaques associated with cardiovascular events. While substantial progress has been realized in clinical molecular imaging of plaques in larger arterial vessels (carotid, aorta, iliac), there remains a compelling, unmet need to develop molecular imaging strategies targeted to high-risk plaques in human coronary arteries. We present recent developments in intravascular near-IR fluorescence catheter-based strategies for in vivo detection of plaque inflammation in coronary-sized arteries. In particular, the biological, light transmission, imaging agent, and engineering principles that underlie a new intravascular near-IR fluorescence sensing method are discussed. Intravascular near-IR fluorescence catheters appear highly translatable to the cardiac catheterization laboratory, and thus may offer a new in vivo method to detect high-risk coronary plaques and to assess novel atherosclerosis biologics.

  5. Normal kidney size and renal cortical thickness of the Korean adults

    International Nuclear Information System (INIS)

    Chung, Hee Kyung; Hahm, Chang Kok

    1974-01-01

    1. The kidney size and cortical thickness were measured from intravenous pyelograms of healthy Korean adults of 250 males and 250 females. 2. The measured size and cortical thickness of kidney were following figure (mm). 3. The size of kidney of male is a little larger than female both in vertical length and horizontal width. 4. The renal cortical thickness were not significant in differences between male and female, right and left, in each poles. 5. In the study of distribution of length differences between pairs of kidneys in our series, the length of right kidney is larger in 18.6%, and width in 27.2%. 6. Comparative study is carried out measuring the length of first lumbar vertebral bodies including 4 intervertebral spaces. 7. The site of kidney is larger in the group of greater length of vertebral height. 8. The renal cortical thickness have no significant differences in according to the differences of length of vertebral height, in each poles. 9. Comparing with the western authors, the kidney size of the Korean adult is not smaller than western

  6. Finite size effects in neutron star and nuclear matter simulations

    Energy Technology Data Exchange (ETDEWEB)

    Giménez Molinelli, P.A., E-mail: pagm@df.uba.ar; Dorso, C.O.

    2015-01-15

    In this work we study molecular dynamics simulations of symmetric nuclear and neutron star matter using a semi-classical nucleon interaction model. Our aim is to gain insight on the nature of the so-called “finite size effects”, unavoidable in this kind of simulations, and to understand what they actually affect. To do so, we explore different geometries for the periodic boundary conditions imposed on the simulation cell: cube, hexagonal prism and truncated octahedron. For nuclear matter simulations we show that, at sub-saturation densities and low temperatures, the solutions are non-homogeneous structures reminiscent of the “nuclear pasta” phases expected in neutron star matter simulations, but only one structure per cell and shaped by specific artificial aspects of the simulations—for the same physical conditions (i.e. number density and temperature) different cells yield different solutions. The particular shape of the solution at low enough temperature and a given density can be predicted analytically by surface minimization. We also show that even if this behavior is due to the imposition of periodic boundary conditions on finite systems, this does not mean that it vanishes for very large systems, and it is actually independent of the system size. We conclude that, for nuclear matter simulations, the cells' size sets the only characteristic length scale for the inhomogeneities, and the geometry of the periodic cell determines the shape of those inhomogeneities. To model neutron star matter we add a screened Coulomb interaction between protons, and perform simulations in the three cell geometries. Our simulations indeed produce the well known nuclear pasta, with (in most cases) several structures per cell. However, we find that for systems not too large results are affected by finite size in different ways depending on the geometry of the cell. In particular, at the same certain physical conditions and system size, the hexagonal prism yields a

  7. Evolution of body size in Galapagos marine iguanas.

    Science.gov (United States)

    Wikelski, Martin

    2005-10-07

    Body size is one of the most important traits of organisms and allows predictions of an individual's morphology, physiology, behaviour and life history. However, explaining the evolution of complex traits such as body size is difficult because a plethora of other traits influence body size. Here I review what we know about the evolution of body size in a group of island reptiles and try to generalize about the mechanisms that shape body size. Galapagos marine iguanas occupy all 13 larger islands in this Pacific archipelago and have maximum island body weights between 900 and 12 000g. The distribution of body sizes does not match mitochondrial clades, indicating that body size evolves independently of genetic relatedness. Marine iguanas lack intra- and inter-specific food competition and predators are not size-specific, discounting these factors as selective agents influencing body size. Instead I hypothesize that body size reflects the trade-offs between sexual and natural selection. We found that sexual selection continuously favours larger body sizes. Large males establish display territories and some gain over-proportional reproductive success in the iguanas' mating aggregations. Females select males based on size and activity and are thus responsible for the observed mating skew. However, large individuals are strongly selected against during El Niño-related famines when dietary algae disappear from the intertidal foraging areas. We showed that differences in algae sward ('pasture') heights and thermal constraints on large size are causally responsible for differences in maximum body size among populations. I hypothesize that body size in many animal species reflects a trade-off between foraging constraints and sexual selection and suggest that future research could focus on physiological and genetic mechanisms determining body size in wild animals. Furthermore, evolutionary stable body size distributions within populations should be analysed to better

  8. Body size, performance and fitness in galapagos marine iguanas.

    Science.gov (United States)

    Wikelski, Martin; Romero, L Michael

    2003-07-01

    Complex organismal traits such as body size are influenced by innumerable selective pressures, making the prediction of evolutionary trajectories for those traits difficult. A potentially powerful way to predict fitness in natural systems is to study the composite response of individuals in terms of performance measures, such as foraging or reproductive performance. Once key performance measures are identified in this top-down approach, we can determine the underlying physiological mechanisms and gain predictive power over long-term evolutionary processes. Here we use marine iguanas as a model system where body size differs by more than one order of magnitude between island populations. We identified foraging efficiency as the main performance measure that constrains body size. Mechanistically, foraging performance is determined by food pasture height and the thermal environment, influencing intake and digestion. Stress hormones may be a flexible way of influencing an individual's response to low-food situations that may be caused by high population density, famines, or anthropogenic disturbances like oil spills. Reproductive performance, on the other hand, increases with body size and is mediated by higher survival of larger hatchlings from larger females and increased mating success of larger males. Reproductive performance of males may be adjusted via plastic hormonal feedback mechanisms that allow individuals to assess their social rank annually within the current population size structure. When integrated, these data suggest that reproductive performance favors increased body size (influenced by reproductive hormones), with an overall limit imposed by foraging performance (influenced by stress hormones). Based on our mechanistic understanding of individual performances we predicted an evolutionary increase in maximum body size caused by global warming trends. We support this prediction using specimens collected during 1905. We also show in a common

  9. Evaluation of actual vs expected photodynamic therapy spot size.

    Science.gov (United States)

    Ranchod, Tushar M; Brucker, Alexander J; Liu, Chengcheng; Cukras, Catherine A; Hopkins, Tim B; Ying, Gui-Shuang

    2009-05-01

    To determine the accuracy of the photodynamic therapy (PDT) laser spot size on the retina as generated by 2 Food and Drug Administration (FDA)-approved lasers. Prospective observational case series. Fundus photographs were taken of 1 eye of each of 10 subjects with the WinStation 4000 fundus photography system (OIS; Ophthalmic Imaging Systems, Sacramento, California, USA); disc size was calculated using OIS software. Slit-lamp photographs were taken of the PDT laser spot focused on the retina adjacent to the optic disc, using various spot sizes in combination with 3 different contact lenses and 2 different lasers. Spot size at the retina was determined by measuring the ratio of disc diameter to spot diameter in Adobe Photoshop (San Jose, California, USA) and applying this ratio to the OIS disc measurements. Spot size at the retina averaged 87% of expected spot size for the Coherent Opal laser (Coherent Inc, Santa Clara, California, USA) and 104% of expected spot size for the Zeiss Visulas laser (Carl Zeiss Meditec Inc, Dublin, California, USA)(P = .002). Multivariate analysis demonstrated that percentage of expected spot size decreased with larger spot diameter (P = .01 for Coherent laser; P = .02 for Zeiss laser). PDT spot size at the retina appears to be consistently smaller than expected for the Coherent laser while the spot size was consistently within 10% of expected size for the Zeiss laser. The deviation from expected size increased with larger spot size using the Coherent laser.

  10. Heritability of Wing Size and Shape of the Rice and Corn Strains of Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae).

    Science.gov (United States)

    Cañas-Hoyos, N; Márquez, E J; Saldamando-Benjumea, C I

    2016-08-01

    Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) represents a pest of economic importance in all Western Hemisphere. This polyphagous species has diverged into two populations that have been mainly recognized with various mitochondrial and nuclear molecular markers and named "the rice" and "the corn" strains. In Colombia, both strains have evolved prezygotic and postzygotic isolation. They differ in tolerance to Bacillus thuringiensis (Cry1Ac and Cry1Ab endotoxins) and the insecticides lambda-cyhalothrin and methomyl. In 2014, a wing morphometric analysis made in 159 individuals from a colony showed that both strains significantly differ in wing shape. The species also exhibits sexual dimorphism in the rice strain as in females wing size is larger than in males. Here, we continued this work with another wing morphometric approach in laboratory-reared strains to calculate wing size and shape heritabilities using a full-sib design and in wild populations to determine if this method distinguishes these strains. Our results show that male heritabilities of both traits were higher than female ones. Wild populations were significantly different in wing shape and size. These results suggest that wing morphometrics can be used as an alternative method to molecular markers to differentiate adults from laboratory-reared populations and wild populations of this pest, particularly in males of this species. Finally, Q ST values obtained for wing size and shape further demonstrated that both strains are genetically differentiated in nature.

  11. The relationship between UT reported size and actual size of the defects in rotor forgings

    International Nuclear Information System (INIS)

    Seong, Un Hak; Kim, Jeong Tae; Park, Yun Sik

    2003-01-01

    In order to evaluate the reliability of rotor forgings, it is very important to know the actual size of the defects in the rotor forgings. The determination of the defect size requires the accurate non-destructive measurement. However, there may be some differences between the reported size with the ultrasonic non-destructive testing method and the actual size of defects. These differences may be a severe cause of errors in evaluation of rotor forgings. So, the calculated size with 'Master Curve' considering safety factor, which is usually larger than the reported size, has been used in evaluation of rotor forgings. The relation between the EFBH (Equivalent Flat Bottom Hole) size measured by non-destructive method and the actual size by destructive method in many rotors manufactured at Doosan was investigated. In this investigation 'Master Curve' compensating the differences between UT reported size and actual size of defects in our rotor forgings was obtainable. The applicability of this 'Master Curve' as a way of calculating the actual defect size was also investigated. For the evaluation of rotor forgings, it is expected that this 'Master Curve' may be used to determine the accurate actual size of defects.

  12. The relationship between UT reported size and actual size of the defects in rotor forgings

    International Nuclear Information System (INIS)

    Seong, Un Hak; Kim, Jeong Tae; Park, Yun Sik

    2003-01-01

    In order to evaluate the reliability of rotor forgings, it is very important to know the actual size of the defects in the rotor forgings. The determination of the defect size requires the accurate non-destructive measurement. However, there may be some difference between the reported size with ultrasonic non-destructive testing method and the actual size of defects. These differences may be a severe cause of errors in evaluation of rotor forgings. So, the calculated size with 'Master Curve' considering safety factor, which is usually larger than the reported size, has been used in evaluation of rotor forgings. The relation between the EFBH (Equivalent Flat Bottom Hole) size measured by non-destructive method and the actual size by destructive method in many rotors manufactured at Doosan was investigated. In this investigation, 'Master Curve' compensating the differences between UT reported size and actual size of defects in our rotor forgings was obtainable. The applicability of this 'Master Curve' as a way of calculating the actual defect size was also investigated. For the evaluation of rotor forgings, it is expected that this 'Master Curve' may be used to determine the accurate actual size of defects.

  13. Combining Pickering Emulsion Polymerization with Molecular Imprinting to Prepare Polymer Microspheres for Selective Solid-Phase Extraction of Malachite Green

    Directory of Open Access Journals (Sweden)

    Weixin Liang

    2017-08-01

    Full Text Available Malachite green (MG is currently posing a carcinogenic threat to the safety of human lives; therefore, it is highly desirable to develop an effective method for fast trace detection of MG. Herein, for the first time, this paper presents a systematic study on polymer microspheres, being prepared by combined Pickering emulsion polymerization and molecular imprinting, to detect and purify MG. The microspheres, molecularly imprinted with MG, show enhanced adsorption selectivity to MG, despite a somewhat lowered adsorption capacity, as compared to the counterpart without molecular imprinting. Structural features and adsorption performance of these microspheres are elucidated by different characterizations and kinetic and thermodynamic analyses. The surface of the molecularly imprinted polymer microspheres (M-PMs exhibits regular pores of uniform pore size distribution, endowing M-PMs with impressive adsorption selectivity to MG. In contrast, the microspheres without molecular imprinting show a larger average particle diameter and an uneven porous surface (with roughness and a large pore size, causing a lower adsorption selectivity to MG despite a higher adsorption capacity. Various adsorption conditions are investigated, such as pH and initial concentration of the solution with MG, for optimizing the adsorption performance of M-PMs in selectively tackling MG. The adsorption kinetics and thermodynamics are deeply discussed and analyzed, so as to provide a full picture of the adsorption behaviors of the polymer microspheres with and without the molecular imprinting. Significantly, M-PMs show promising solid-phase extraction column applications for recovering MG in a continuous extraction manner.

  14. DISSOLVED ORGANIC-MATTER, CADMIUM, COPPER AND ZINC IN PIG SLURRY-SIZE AND SOIL SOLUTION-SIZE EXCLUSION CHROMATOGRAPHY FRACTIONS

    NARCIS (Netherlands)

    DELCASTILHO, P; DALENBERG, JW; BRUNT, K; BRUINS, AP

    1993-01-01

    Sephadex size exclusion chromatography was used to prepare molecular size fractions from liquid pig slurry, before and after aerobic interaction with a loamy-sand soil. In the liquid fractions organic matter was characterized and some components were identified. The distribution of zinc and copper

  15. Correlation Between Echinoidea Size and Threat Level

    Science.gov (United States)

    Bakshi, S.; Lee, A.; Heim, N.; Payne, J.

    2017-12-01

    Echinoidea (or sea urchins), are small, spiny, globular, animals that populate the seafloors of nearly the entire planet. Echinoidea have existed on Earth since the Ordovician period, and from their archaic origin there is much to be learned about the relationship between Echinoidea body size and how it affects the survivability of the individual. The goal of this project is to determine how Echinoidea dimensions such as body volume, area, and length compare across extinct and extant species by plotting Echinoidea data in R. We will use stratigraphic data as a source to find which species of sea urchin from our data is extinct. We will then create three sets of three histograms of the size data for each type of measurement. One set will include histograms for sea urchin length, area, and volume. The other set will include histograms for extinct sea urchin length, area, and volume. The last set will include histograms for extant sea urchin length, area, and volume. Our data showed that extant sea urchins had a larger size, and extinct sea urchins were smaller. Our length data showed that the average length of all sea urchins were 54.95791 mm, the average length of extinct sea urchins were 51.0337 mm, and the average length of extant sea urchins were 66.12774 mm. There is a generally increasing trend of size over time, except for a small outlier about 350 million years ago, where echinoderm extinction selected towards larger species and biovolume was abnormally high. Our data also showed that over the past 200 million years, echinoderm extinction selectivity drove slightly smaller sea urchins towards extinction, further supporting the idea that a larger size was and still is advantageous for echinoderms.

  16. Effects of patch size on feeding associations in muriquis (Brachyteles arachnoides).

    Science.gov (United States)

    Strier, K B

    1989-01-01

    Data were collected on one group of muriquis, or woolly spider monkeys (Brachyteles arachnoides) during a 14-month study at Fazenda Montes Claros, Minas Gerais, Brazil to examine the effects of food patch size on muriqui feeding associations. Muriqui food patches were larger than expected from the availability of patch sizes in the forest; fruit patches were significantly larger than leaf patches. Feeding aggregate size, the maximum number of simultaneous occupants, and patch occupancy time were positively related to the size of fruit patches. However, a greater number of individuals fed at leaf sources than expected from the size of these patches. Adult females tended to feed alone in patches more often than males, whereas males tended to feed in single-sexed groups more often than females. Yet in neither case were these differences statistically significant.

  17. Comparative characterization of humic substances extracted from freshwater and peat of different apparent molecular sizes

    Directory of Open Access Journals (Sweden)

    Eliane Sloboda Rigobello

    2017-09-01

    Full Text Available This paper compares the structural characteristics of aquatic humic substances (AHS with humic substances from peat (HSP through different analytical techniques, including elemental analysis, solid state 13C cross polarization/magic-angle-spinning nuclear magnetic resonance spectroscopy (13C CP-MAS NMR, ultraviolet/visible (UV/Vis spectroscopy and Fourier transform infrared (FTIR spectroscopy and total organic carbon (TOC. The AHS were extracted from water collected in a tributary of the Itapanhaú River (Bertioga/SP using XAD 8 resin, and the HSP were extracted from peat collected in the Mogi Guaçu River bank (Luis Antonio/SP with a KOH solution. After dialysis, both AHS and HSP extracts were filtered in membrane of 0.45 µm pore size (Fraction F1: < 0.45 µm and fractioned by ultrafiltration in different apparent molecular sizes (AMS (F2: 100 kDa-0.45 μm; F3: 30 kDa-100 kDa and F4: < 30 kDa. The extracts with the lowest AMS (F3 and F4 showed a higher number of aliphatic carbons than aromatic carbons, a higher concentration of groups containing oxygen and a higher percentage of fulvic acids (FA than humic acids (HA for both AHS and HSP. However, the AHS presented higher FA than HA content in relation to the HSP and distinct structural properties.

  18. Energetic tradeoffs control the size distribution of aquatic mammals

    Science.gov (United States)

    Gearty, William; McClain, Craig R.; Payne, Jonathan L.

    2018-04-01

    Four extant lineages of mammals have invaded and diversified in the water: Sirenia, Cetacea, Pinnipedia, and Lutrinae. Most of these aquatic clades are larger bodied, on average, than their closest land-dwelling relatives, but the extent to which potential ecological, biomechanical, and physiological controls contributed to this pattern remains untested quantitatively. Here, we use previously published data on the body masses of 3,859 living and 2,999 fossil mammal species to examine the evolutionary trajectories of body size in aquatic mammals through both comparative phylogenetic analysis and examination of the fossil record. Both methods indicate that the evolution of an aquatic lifestyle is driving three of the four extant aquatic mammal clades toward a size attractor at ˜500 kg. The existence of this body size attractor and the relatively rapid selection toward, and limited deviation from, this attractor rule out most hypothesized drivers of size increase. These three independent body size increases and a shared aquatic optimum size are consistent with control by differences in the scaling of energetic intake and cost functions with body size between the terrestrial and aquatic realms. Under this energetic model, thermoregulatory costs constrain minimum size, whereas limitations on feeding efficiency constrain maximum size. The optimum size occurs at an intermediate value where thermoregulatory costs are low but feeding efficiency remains high. Rather than being released from size pressures, water-dwelling mammals are driven and confined to larger body sizes by the strict energetic demands of the aquatic medium.

  19. LINEAR RELATION FOR WIND-BLOWN BUBBLE SIZES OF MAIN-SEQUENCE OB STARS IN A MOLECULAR ENVIRONMENT AND IMPLICATION FOR SUPERNOVA PROGENITORS

    Energy Technology Data Exchange (ETDEWEB)

    Chen Yang; Zhou Ping [Department of Astronomy, Nanjing University, Nanjing 210093 (China); Chu Youhua [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States)

    2013-05-20

    We find a linear relationship between the size of a massive star's main-sequence bubble in a molecular environment and the star's initial mass: R{sub b} Almost-Equal-To 1.22 M/M{sub Sun} - 9.16 pc, assuming a constant interclump pressure. Since stars in the mass range of 8 to 25-30 M{sub Sun} will end their evolution in the red supergiant phase without launching a Wolf-Rayet wind, the main-sequence wind-blown bubbles are mainly responsible for the extent of molecular gas cavities, while the effect of the photoionization is comparatively small. This linear relation can thus be used to infer the masses of the massive star progenitors of supernova remnants (SNRs) that are discovered to evolve in molecular cavities, while few other means are available for inferring the properties of SNR progenitors. We have used this method to estimate the initial masses of the progenitors of eight SNRs: Kes 69, Kes 75, Kes 78, 3C 396, 3C 397, HC 40, Vela, and RX J1713-3946.

  20. Myonuclear domain size and myosin isoform expression in muscle fibres from mammals representing a 100,000-fold difference in body size.

    Science.gov (United States)

    Liu, Jing-Xia; Höglund, Anna-Stina; Karlsson, Patrick; Lindblad, Joakim; Qaisar, Rizwan; Aare, Sudhakar; Bengtsson, Ewert; Larsson, Lars

    2009-01-01

    This comparative study of myonuclear domain (MND) size in mammalian species representing a 100,000-fold difference in body mass, ranging from 25 g to 2500 kg, was undertaken to improve our understanding of myonuclear organization in skeletal muscle fibres. Myonuclear domain size was calculated from three-dimensional reconstructions in a total of 235 single muscle fibre segments at a fixed sarcomere length. Irrespective of species, the largest MND size was observed in muscle fibres expressing fast myosin heavy chain (MyHC) isoforms, but in the two smallest mammalian species studied (mouse and rat), MND size was not larger in the fast-twitch fibres expressing the IIA MyHC isofom than in the slow-twitch type I fibres. In the larger mammals, the type I fibres always had the smallest average MND size, but contrary to mouse and rat muscles, type IIA fibres had lower mitochondrial enzyme activities than type I fibres. Myonuclear domain size was highly dependent on body mass in the two muscle fibre types expressed in all species, i.e. types I and IIA. Myonuclear domain size increased in muscle fibres expressing both the beta/slow (type I; r = 0.84, P fast IIA MyHC isoform (r = 0.90; P muscle fibre type, independent of species. However, myosin isoform expression is not the sole protein determining MND size, and other protein systems, such as mitochondrial proteins, may be equally or more important determinants of MND size.

  1. Concerted evolution of body mass and cell size: similar patterns among species of birds (Galliformes) and mammals (Rodentia)

    Science.gov (United States)

    Dragosz-Kluska, Dominika; Pis, Tomasz; Pawlik, Katarzyna; Kapustka, Filip; Kilarski, Wincenty M.; Kozłowski, Jan

    2018-01-01

    ABSTRACT Cell size plays a role in body size evolution and environmental adaptations. Addressing these roles, we studied body mass and cell size in Galliformes birds and Rodentia mammals, and collected published data on their genome sizes. In birds, we measured erythrocyte nuclei and basal metabolic rates (BMRs). In birds and mammals, larger species consistently evolved larger cells for five cell types (erythrocytes, enterocytes, chondrocytes, skin epithelial cells, and kidney proximal tubule cells) and evolved smaller hepatocytes. We found no evidence that cell size differences originated through genome size changes. We conclude that the organism-wide coordination of cell size changes might be an evolutionarily conservative characteristic, and the convergent evolutionary body size and cell size changes in Galliformes and Rodentia suggest the adaptive significance of cell size. Recent theory predicts that species evolving larger cells waste less energy on tissue maintenance but have reduced capacities to deliver oxygen to mitochondria and metabolize resources. Indeed, birds with larger size of the abovementioned cell types and smaller hepatocytes have evolved lower mass-specific BMRs. We propose that the inconsistent pattern in hepatocytes derives from the efficient delivery system to hepatocytes, combined with their intense involvement in supracellular function and anabolic activity. PMID:29540429

  2. Concerted evolution of body mass and cell size: similar patterns among species of birds (Galliformes and mammals (Rodentia

    Directory of Open Access Journals (Sweden)

    Marcin Czarnoleski

    2018-04-01

    Full Text Available Cell size plays a role in body size evolution and environmental adaptations. Addressing these roles, we studied body mass and cell size in Galliformes birds and Rodentia mammals, and collected published data on their genome sizes. In birds, we measured erythrocyte nuclei and basal metabolic rates (BMRs. In birds and mammals, larger species consistently evolved larger cells for five cell types (erythrocytes, enterocytes, chondrocytes, skin epithelial cells, and kidney proximal tubule cells and evolved smaller hepatocytes. We found no evidence that cell size differences originated through genome size changes. We conclude that the organism-wide coordination of cell size changes might be an evolutionarily conservative characteristic, and the convergent evolutionary body size and cell size changes in Galliformes and Rodentia suggest the adaptive significance of cell size. Recent theory predicts that species evolving larger cells waste less energy on tissue maintenance but have reduced capacities to deliver oxygen to mitochondria and metabolize resources. Indeed, birds with larger size of the abovementioned cell types and smaller hepatocytes have evolved lower mass-specific BMRs. We propose that the inconsistent pattern in hepatocytes derives from the efficient delivery system to hepatocytes, combined with their intense involvement in supracellular function and anabolic activity.

  3. Nano- and Micro-sized Molecularly Imprinted Polymer Particles on Solid Surfaces

    OpenAIRE

    Kamra, Tripta

    2015-01-01

    Molecularly imprinted polymers (MIPs) are artificial receptors made by imprinting template molecules in a polymer matrix followed by their removal through washing to obtain a specific and selective template cavities. This property of the MIPs have made them a very efficient material for diverse applications such as chromatography, purification, drug sensing, etc. Recently, zero-dimensional polymer materials, in the present case molecularly imprinted polymer nanoparticles (MIP nanoparticles), ...

  4. A hybrid particle–field molecular dynamics approach: a route toward efficient coarse-grained models for biomembranes

    International Nuclear Information System (INIS)

    Milano, Giuseppe; De Nicola, Antonio; Kawakatsu, Toshihiro

    2013-01-01

    This paper gives an overview of the coarse-grained models of phospholipids recently developed by the authors in the frame of a hybrid particle–field molecular dynamics technique. This technique employs a special class of coarse-grained models that are gaining popularity because they allow simulations of large scale systems and, at the same time, they provide sufficiently detailed chemistry for the mapping scheme adopted. The comparison of the computational costs of our approach with standard molecular dynamics simulations is a function of the system size and the number of processors employed in the parallel calculations. Due to the low amount of data exchange, the larger the number of processors, the better are the performances of the hybrid particle–field models. This feature makes these models very promising ones in the exploration of several problems in biophysics. (paper)

  5. Allometry of sexual size dimorphism in domestic dog.

    Directory of Open Access Journals (Sweden)

    Daniel Frynta

    Full Text Available The tendency for male-larger sexual size dimorphism (SSD to scale with body size - a pattern termed Rensch's rule - has been empirically supported in many animal lineages. Nevertheless, its theoretical elucidation is a subject of debate. Here, we exploited the extreme morphological variability of domestic dog (Canis familiaris to gain insights into evolutionary causes of this rule.We studied SSD and its allometry among 74 breeds ranging in height from less than 19 cm in Chihuahua to about 84 cm in Irish wolfhound. In total, the dataset included 6,221 individuals. We demonstrate that most dog breeds are male-larger, and SSD in large breeds is comparable to SSD of their wolf ancestor. Among breeds, SSD becomes smaller with decreasing body size. The smallest breeds are nearly monomorphic.SSD among dog breeds follows the pattern consistent with Rensch's rule. The variability of body size and corresponding changes in SSD among breeds of a domestic animal shaped by artificial selection can help to better understand processes leading to emergence of Rensch's rule.

  6. Interpretations of family size distributions: The Datura example

    Science.gov (United States)

    Henych, Tomáš; Holsapple, Keith A.

    2018-04-01

    Young asteroid families are unique sources of information about fragmentation physics and the structure of their parent bodies, since their physical properties have not changed much since their birth. Families have different properties such as age, size, taxonomy, collision severity and others, and understanding the effect of those properties on our observations of the size-frequency distribution (SFD) of family fragments can give us important insights into the hypervelocity collision processes at scales we cannot achieve in our laboratories. Here we take as an example the very young Datura family, with a small 8-km parent body, and compare its size distribution to other families, with both large and small parent bodies, and created by both catastrophic and cratering formation events. We conclude that most likely explanation for the shallower size distribution compared to larger families is a more pronounced observational bias because of its small size. Its size distribution is perfectly normal when its parent body size is taken into account. We also discuss some other possibilities. In addition, we study another common feature: an offset or "bump" in the distribution occurring for a few of the larger elements. We hypothesize that it can be explained by a newly described regime of cratering, "spall cratering", which controls the majority of impact craters on the surface of small asteroids like Datura.

  7. Object size effects on initial lifting forces under microgravity conditions

    NARCIS (Netherlands)

    Kingma, I.; Savelsbergh, G.J.P.; Toussaint, H.M.

    1999-01-01

    Individuals usually report for two objects of equal mass but different volume that the larger object feels lighter. This so-called size-weight illusion has been investigated for more than a century. The illusion is accompanied by increased forces, used to lift the larger object, resulting in a

  8. Size distributions and dispersions along a 485-year chronosequence for sand dune vegetation.

    Science.gov (United States)

    Waugh, Jennifer M; Aarssen, Lonnie W

    2012-04-01

    Using a sand dune chronosequence that spans 485 years of primary succession, we collected nearest-neighbor vegetation data to test two predictions associated with the traditional "size-advantage" hypothesis for plant competitive ability: (1) the relative representation of larger species should increase in later stages of succession; and (2) resident species that are near neighbors should, over successional time, become more similar in plant body size and/or seed size than expected by random assembly. The first prediction was supported over the time period between mid to later succession, but the second prediction was not; that is, there was no temporal pattern across the chronosequence indicating that either larger resident species, or larger seeded resident species, increasingly exclude smaller ones from local neighborhoods over time. Rather, neighboring species were generally more different from each other in seed sizes than expected by random assembly. As larger species accumulate over time, some relatively small species are lost from later stages of succession, but species size distributions nevertheless remain strongly right-skewed-even in late succession-and species of disparate sizes are just as likely as in early succession to coexist as immediate neighbors. This local-scale coexistence of disparate sized neighbors might be accounted for-as in traditional interpretations-in terms of species differences in "physical-space-niches" (e.g., involving different rooting depths), combined with possible facilitation effects. We propose, however, that this coexistence may also occur because competitive ability involves more than just a size advantage, with traits associated with survival (tolerance of intense competition) and fecundity (offspring production despite intense competition) being at least equally important.

  9. Spatially extended and high-velocity dispersion molecular component in spiral galaxies: Single-dish versus interferometric observations

    International Nuclear Information System (INIS)

    Caldú-Primo, Anahi; Walter, Fabian; Schruba, Andreas; Leroy, Adam; Bolatto, Alberto D.; Vogel, Stuart

    2015-01-01

    Recent studies of the molecular medium in nearby galaxies have provided mounting evidence that the molecular gas can exist in two phases: one that is clumpy and organized as molecular clouds and another one that is more diffuse. This last component has a higher velocity dispersion than the clumpy one. In order to investigate these two molecular components further, we compare the fluxes and line widths of CO in NGC 4736 and NGC 5055, two nearby spiral galaxies for which high-quality interferometric as well as single-dish data sets are available. Our analysis leads to two main results: (1) employing three different methods, we determine the flux recovery of the interferometer as compared to the single-dish to be within a range of 35%–74% for NGC 4736 and 81%–92% for NGC 5055, and (2) when focusing on high (S/N ≥ 5) lines of sight (LOSs), the single-dish line widths are larger by ∼(40 ± 20)% than the ones derived from interferometric data, which is in agreement with stacking all LOSs. These results point to a molecular gas component that is distributed over spatial scales larger than 30″(∼1 kpc), and is therefore filtered out by the interferometer. The available observations do not allow us to distinguish between a truly diffuse gas morphology and a uniform distribution of small clouds that are separated by less than the synthesized beam size (∼3″ or ∼100 pc), as they would both be invisible for the interferometer. This high velocity dispersion component has a dispersion similar to what is found in the atomic medium, as traced through observations of the H i line.

  10. Simulation of the measure of the microparticle size distribution in two dimensions

    International Nuclear Information System (INIS)

    Lameiras, F.S.; Pinheiro, P.

    1987-01-01

    Different size distributions of plane figures were generated in a computer as a simply connected network. These size distributions were measured by the Saltykov method for two dimensions. The comparison between the generated and measured distributions showed that the Saltkov method tends to measure larger scattering than the real one and to move the maximum of the real distribution to larger diameters. These erros were determined by means of the ratio of the perimeter of the figures per unit area directly measured and the perimeter calculated from the size distribution obtained by using the SaltyKov method. (Author) [pt

  11. Radiation-induced chemical reaction of methane in the presence of X-and Y-type molecular sieves

    International Nuclear Information System (INIS)

    Shimizu, Y.; Nagai, S.

    1990-01-01

    The radiolysis of methane was investigated in the presence of X (13X) and Y (SK-40) type molecular sieves at 300 0 C. Product analysis showed that irradiation of methane over 13X and SK-40 produces hydrogen and hydrocarbons up to C 5 . The yields of hydrocarbons, except for ethylene, over 13X and SK-40 slightly increased with irradiation time. The yields of the main hydrocarbon products over SK-40 were larger than those in the absence of molecular sieve in contrast to those over 13X. It was found that no 13X shows catalytic activity for the radiolysis of methane; on the other hand, SK-40 shows it. The relations between the proportion of hydrocarbon yield of each carbon number to the hydrocarbon total yield over 13X and SK-40 and the carbon number were the same as those in the absence of molecular sieve. It was proved by comparison of these results with those over A-type molecular sieve (5A) that the order of the catalytic activities of the molecular sieves for the radiolysis of methane differs considerably from that found in thermal catalytic reactions. These results are discussed in terms of the concept of energy transfer and the relation between the pore size of the molecular sieves and the molecular diameters of the hydrocarbons produced. (author)

  12. Maternal effects of egg size on emu Dromaius novaehollandiae egg composition and hatchling phenotype.

    Science.gov (United States)

    Dzialowski, Edward M; Sotherland, Paul R

    2004-02-01

    Parental investment in eggs and, consequently, in offspring can profoundly influence the phenotype, survival and ultimately evolutionary fitness of an organism. Avian eggs are excellent model systems to examine maternal allocation of energy translated through egg size variation. We used the natural range in emu Dromaius novaehollandiae egg size, from 400 g to >700 g, to examine the influence of maternal investment in eggs on the morphology and physiology of hatchlings. Female emus provisioned larger eggs with a greater absolute amount of energy, nutrients and water in the yolk and albumen. Variation in maternal investment was reflected in differences in hatchling size, which increased isometrically with egg size. Egg size also influenced the physiology of developing emu embryos, such that late-term embryonic metabolic rate was positively correlated with egg size and embryos developing in larger eggs consumed more yolk during development. Large eggs produced hatchlings that were both heavier (yolk-free wet and dry mass) and structurally larger (tibiotarsus and culmen lengths) than hatchlings emerging from smaller eggs. As with many other precocial birds, larger hatchlings also contained more water, which was reflected in a greater blood volume. However, blood osmolality, hemoglobin content and hematocrit did not vary with hatchling mass. Emu maternal investment in offspring, measured by egg size and composition, is significantly correlated with the morphology and physiology of hatchlings and, in turn, may influence the success of these organisms during the first days of the juvenile stage.

  13. Geographical variation in body size and sexual size dimorphism in an Australian lizard, Boulenger's Skink (Morethia boulengeri).

    Science.gov (United States)

    Michael, Damian R; Banks, Sam C; Piggott, Maxine P; Cunningham, Ross B; Crane, Mason; MacGregor, Christopher; McBurney, Lachlan; Lindenmayer, David B

    2014-01-01

    Ecogeographical rules help explain spatial and temporal patterns in intraspecific body size. However, many of these rules, when applied to ectothermic organisms such as reptiles, are controversial and require further investigation. To explore factors that influence body size in reptiles, we performed a heuristic study to examine body size variation in an Australian lizard, Boulenger's Skink Morethia boulengeri from agricultural landscapes in southern New South Wales, south-eastern Australia. We collected tissue and morphological data on 337 adult lizards across a broad elevation and climate gradient. We used a model-selection procedure to determine if environmental or ecological variables best explained body size variation. We explored the relationship between morphology and phylogenetic structure before modeling candidate variables from four broad domains: (1) geography (latitude, longitude and elevation), (2) climate (temperature and rainfall), (3) habitat (vegetation type, number of logs and ground cover attributes), and (4) management (land use and grazing history). Broad phylogenetic structure was evident, but on a scale larger than our study area. Lizards were sexually dimorphic, whereby females had longer snout-vent length than males, providing support for the fecundity selection hypothesis. Body size variation in M. boulengeri was correlated with temperature and rainfall, a pattern consistent with larger individuals occupying cooler and more productive parts of the landscape. Climate change forecasts, which predict warmer temperature and increased aridity, may result in reduced lizard biomass and decoupling of trophic interactions with potential implications for community organization and ecosystem function.

  14. Ultraviolet (UV) disinfection of grey water: particle size effects.

    Science.gov (United States)

    Winward, G P; Avery, L M; Stephenson, T; Jefferson, B

    2008-02-01

    The impact of water quality on the ultraviolet (UV) disinfection of grey water was investigated with reference to urban water reuse. Direct UV disinfection of grey water did not meet the stringent California State Title 22 criteria for unrestricted urban water reuse due to the presence of particulate material ranging from or = 2000 microm in size. Grey water was manipulated by settling to produce fractions of varying particle size distributions and blending was employed post-disinfection to extract particle-associated coliforms (PACs). The efficacy of UV disinfection was found to be linked to the particle size of the grey water fractions. The larger particle size fractions with a mean particle size of 262 microm and above were observed to shield more coliforms from UV light than did the smaller particles with a mean particle size below 119 microm. Up to 70% of total coliforms in the larger particle size fractions were particle-associated following a UV dose (fluence) of 260 mJ.cm(-2) and would remain undetected by standard coliform enumeration techniques. Implications for urban water reuse are discussed and recommendations made for grey water treatment to ensure removal of particle-associated indicator bacteria and pathogens prior to UV disinfection.

  15. Production of sized particles of uranium oxides and uranium oxyfluorides

    International Nuclear Information System (INIS)

    Knudsen, I.E.; Randall, C.C.

    1976-01-01

    A process is claimed for converting uranium hexafluoride (UF 6 ) to uranium dioxide (UO 2 ) of a relatively large particle size in a fluidized bed reactor by mixing uranium hexafluoride with a mixture of steam and hydrogen and by preliminary reacting in an ejector gaseous uranium hexafluoride with steam and hydrogen to form a mixture of uranium and oxide and uranium oxyfluoride seed particles of varying sizes, separating the larger particles from the smaller particles in a cyclone separator, recycling the smaller seed particles through the ejector to increase their size, and introducing the larger seed particles from the cyclone separator into a fluidized bed reactor where the seed particles serve as nuclei on which coarser particles of uranium dioxide are formed. 9 claims, 2 drawing figures

  16. MR evaluation of postmenopausal ovarian size. Comparison with surgical specimen

    International Nuclear Information System (INIS)

    Joja, Ikuo; Ishida, Kana; Matsushita, Toshi; Mimura, Seiichi; Yamaguchi, Takuya; Akagi, Noriaki; Miyagi, Yasunari; Hara, Takeshi; Kanazawa, Susumu

    2008-01-01

    We investigated ovarian size after menopause using magnetic resonance (MR) imaging and gross specimens obtained from patients with uterine cancer after menopause in whom normal ovaries were confirmed at the time of surgery. The relationships between size of ovarian long axis and age, the number of years since menopause, and age at menopause were statistically evaluated for 130 ovaries observed in short-axis T 2 -weighted MR images of the uterine corpus and in 147 ovarian gross specimens. No significant relationships were found between size of ovarian long axis and these 3 factors. When the sizes of the ovaries in MR images were compared with those in gross specimens, the latter were larger, with a statistically significant difference. Similarly, when the sizes of the ovaries observed or not observed in MR images were compared in gross specimens, the former were larger, with a statistically significant difference. These results indicate that the size of the ovarian long axis observed in MR images does not accurately reflect the true size of the long axis, but ovarian size strongly affects visualization of the ovaries in MR images after menopause. In addition, these results indicate that there are no significant relationships between ovarian size after menopause and age, the number of years since menopause, or age at menopause. (author)

  17. High pressure size exclusion chromatography (HPSEC) determination of dissolved organic matter molecular weight revisited: Accounting for changes in stationary phases, analytical standards, and isolation methods

    Science.gov (United States)

    McAdams, Brandon C.; Aiken, George R.; McKnight, Diane M.; Arnold, William A.; Chin, Yu-Ping

    2018-01-01

    We reassessed the molecular weight of dissolved organic matter (DOM) determined by high pressure size exclusion chromatography (HPSEC) using measurements made with different columns and various generations of polystyrenesulfonate (PSS) molecular weight standards. Molecular weight measurements made with a newer generation HPSEC column and PSS standards from more recent lots are roughly 200 to 400 Da lower than initial measurements made in the early 1990s. These updated numbers match DOM molecular weights measured by colligative methods and fall within a range of values calculated from hydroxyl radical kinetics. These changes suggest improved accuracy of HPSEC molecular weight measurements that we attribute to improved accuracy of PSS standards and changes in the column packing. We also isolated DOM from wetlands in the Prairie Pothole Region (PPR) using XAD-8, a cation exchange resin, and PPL, a styrene-divinylbenzene media, and observed little difference in molecular weight and specific UV absorbance at 280 nm (SUVA280) between the two solid phase extraction resins, suggesting they capture similar DOM moieties. PPR DOM also showed lower SUVA280 at similar weights compared to DOM isolates from a global range of environments, which we attribute to oxidized sulfur in PPR DOM that would increase molecular weight without affecting SUVA280.

  18. High Pressure Size Exclusion Chromatography (HPSEC) Determination of Dissolved Organic Matter Molecular Weight Revisited: Accounting for Changes in Stationary Phases, Analytical Standards, and Isolation Methods.

    Science.gov (United States)

    McAdams, Brandon C; Aiken, George R; McKnight, Diane M; Arnold, William A; Chin, Yu-Ping

    2018-01-16

    We reassessed the molecular weight of dissolved organic matter (DOM) determined by high pressure size exclusion chromatography (HPSEC) using measurements made with different columns and various generations of polystyrenesulfonate (PSS) molecular weight standards. Molecular weight measurements made with a newer generation HPSEC column and PSS standards from more recent lots are roughly 200 to 400 Da lower than initial measurements made in the early 1990s. These updated numbers match DOM molecular weights measured by colligative methods and fall within a range of values calculated from hydroxyl radical kinetics. These changes suggest improved accuracy of HPSEC molecular weight measurements that we attribute to improved accuracy of PSS standards and changes in the column packing. We also isolated DOM from wetlands in the Prairie Pothole Region (PPR) using XAD-8, a cation exchange resin, and PPL, a styrene-divinylbenzene media, and observed little difference in molecular weight and specific UV absorbance at 280 nm (SUVA 280 ) between the two solid phase extraction resins, suggesting they capture similar DOM moieties. PPR DOM also showed lower SUVA 280 at similar weights compared to DOM isolates from a global range of environments, which we attribute to oxidized sulfur in PPR DOM that would increase molecular weight without affecting SUVA 280 .

  19. Ecological correlates of relative brain size in some South African ...

    African Journals Online (AJOL)

    Relative brain size (size of the brain once body size effects have been removed) has been calculated for 16 species of rodent from South Africa and is shown to vary with six species having a positive RBS (that is a brain larger than expected) and 10 a negative RBS. Arboreal species such as Paraxerus cepapi and ...

  20. In silico predictions of LH2 ring sizes from the crystal structure of a single subunit using molecular dynamics simulations.

    Science.gov (United States)

    Janosi, Lorant; Keer, Harindar; Cogdell, Richard J; Ritz, Thorsten; Kosztin, Ioan

    2011-07-01

    Most of the currently known light-harvesting complexes 2 (LH2) rings are formed by 8 or 9 subunits. As of now, questions like "what factors govern the LH2 ring size?" and "are there other ring sizes possible?" remain largely unanswered. Here, we investigate by means of molecular dynamics (MD) simulations and stochastic modeling the possibility of predicting the size of an LH2 ring from the sole knowledge of the high resolution crystal structure of a single subunit. Starting with single subunits of two LH2 rings with known size, that is, an 8-ring from Rs. moliscianum (MOLI) and a 9-ring from Rps. acidophila (ACI), and one with unknown size (referred to as X), we build atomic models of subunit dimers corresponding to assumed 8-, 9-, and 10-ring geometries. After inserting each of the dimers into a lipid-water environment, we determine the preferred angle between the corresponding subunits by three methods: (1) energy minimization, (2) free MD simulations, and (3) potential of mean force calculations. We find that the results from all three methods are consistent with each other, and when taken together, it allows one to predict with reasonable level of confidence the sizes of the corresponding ring structures. One finds that X and ACI very likely form a 9-ring, while MOLI is more likely to form an 8-ring than a 9-ring. Finally, we discuss both the merits and limitations of all three prediction methods. Copyright © 2011 Wiley-Liss, Inc.

  1. A general solution for optimal egg size during external fertilization, extended scope for intermediate optimal egg size and the introduction of Don Ottavio 'tango'

    NARCIS (Netherlands)

    Luttikhuizen, PC; Honkoop, PJC; Drent, J; van der Meer, J

    2004-01-01

    Egg sizes of marine invertebrates vary greatly, both within and between species. Among the proposed causes of this are a trade-off between egg size, egg number and survival probability of offspring, and a selection pressure exerted by sperm limitation during external fertilization. Although larger

  2. The Roles of Size and Size Difference in Australian and Chinese Inter-firm Collaborations

    Directory of Open Access Journals (Sweden)

    Yu Zhang

    Full Text Available There has been considerable debate on the contribution and significance of firm size to the establishment, operation and success of business collaboration. One important source of this debate arises from differing definitions of firm size used in previous research. This paper uses firm size categories and size differences between collaborating firms to examine their contribution to the formation and performance of inter-firmcollaboration in Australia and China. Both qualitative case study and quantitative data analyses are adopted in this paper. Results from both the qualitative case study and quantitative study in Australia and China show that size plays a significant positive role in the formation and performance of business collaboration. Firmsprefer collaborating with larger partners. Bigger firms are more likely to achieve success collaborations. However, size difference plays a negative role in business collaboration. Collaborating with a bigger partner makes it harder to succeed. On the other hand, size and size difference play very different roles in performanceand outcomes of business collaboration in different countries.This paper compares the roles of firm size and size difference in Australian and Chinese inter-firm collaboration. The results provide important strategic implications for business managers, industry regulators, and policy decision makers regarding international business collaboration.

  3. Single-larger-portion-size and dual-column nutrition labeling may help consumers make more healthful food choices.

    Science.gov (United States)

    Lando, Amy M; Lo, Serena C

    2013-02-01

    The Food and Drug Administration is considering changes to the Nutrition Facts label to help consumers make more healthful choices. To examine the effects of modifications to the Nutrition Facts label on foods that can be listed as having 1 or 2 servings per container, but are reasonably consumed at a single eating occasion. Participants were randomly assigned to study conditions that varied on label format, product, and nutrition profile. Data were collected via an online consumer panel. Adults aged 18 years and older were recruited from Synovate's online household panel. Data were collected during August 2011. A total of 32,897 invitations were sent for a final sample of 9,493 interviews. Participants were randomly assigned to one of 10 label formats classified into three groups: listing 2 servings per container with a single column, listing 2 servings per container with a dual column, and listing a single serving per container. Within these groups there were versions that enlarged the font size for "calories," removed "calories from fat," and changed the wording for serving size declaration. The single product task measured product healthfulness, the amount of calories and various nutrients per serving and per container, and label perceptions. The product comparison task measured ability to identify the healthier product and the product with fewer calories per container and per serving. Analysis of covariance models with Tukey-Kramer tests were used. Covariates included general label use, age, sex, level of education, and race/ethnicity. Single-serving and dual-column formats performed better and scored higher on most outcome measures. For products that contain 2 servings but are customarily consumed at a single eating occasion, using a single-serving or dual-column labeling approach may help consumers make healthier food choices. Published by Elsevier Inc.

  4. Molecular Cloud Structures and Massive Star Formation in N159

    Science.gov (United States)

    Nayak, O.; Meixner, M.; Fukui, Y.; Tachihara, K.; Onishi, T.; Saigo, K.; Tokuda, K.; Harada, R.

    2018-02-01

    The N159 star-forming region is one of the most massive giant molecular clouds (GMCs) in the Large Magellanic Cloud (LMC). We show the 12CO, 13CO, CS molecular gas lines observed with ALMA in N159 west (N159W) and N159 east (N159E). We relate the structure of the gas clumps to the properties of 24 massive young stellar objects (YSOs) that include 10 newly identified YSOs based on our search. We use dendrogram analysis to identify properties of the molecular clumps, such as flux, mass, linewidth, size, and virial parameter. We relate the YSO properties to the molecular gas properties. We find that the CS gas clumps have a steeper size–linewidth relation than the 12CO or 13CO gas clumps. This larger slope could potentially occur if the CS gas is tracing shocks. The virial parameters of the 13CO gas clumps in N159W and N159E are low (<1). The threshold for massive star formation in N159W is 501 M ⊙ pc‑2, and the threshold for massive star formation in N159E is 794 M ⊙ pc‑2. We find that 13CO is more photodissociated in N159E than N159W. The most massive YSO in N159E has cleared out a molecular gas hole in its vicinity. All the massive YSO candidates in N159E have a more evolved spectral energy distribution type in comparison to the YSO candidates in N159W. These differences lead us to conclude that the giant molecular cloud complex in N159E is more evolved than the giant molecular cloud complex in N159W.

  5. Surface based detection schemes for molecular interferometry experiments - implications and possible applications

    Science.gov (United States)

    Juffmann, Thomas; Milic, Adriana; Muellneritsch, Michael; Arndt, Markus

    2011-03-01

    Surface based detection schemes for molecular interferometry experiments might be crucial in the search for the quantum properties of larger and larger objects since they provide single particle sensitivity. Here we report on molecular interferograms of different biomolecules imaged using fluorescence microscopy. Being able to watch the build-up of an interferogram live and in situ reveals the matter-wave behavior of these complex molecules in an unprecedented way. We examine several problems encountered due to van-der-Waals forces between the molecules and the diffraction grating and discuss possible ways to circumvent these. Especially the advent of ultra-thin (1-100 atomic layers) diffraction masks might path the way towards molecular holography. We also discuss other possible applications such as coherent molecular microscopy.

  6. THE MAGELLANIC MOPRA ASSESSMENT (MAGMA). I. THE MOLECULAR CLOUD POPULATION OF THE LARGE MAGELLANIC CLOUD

    International Nuclear Information System (INIS)

    Wong, Tony; Chu, You-Hua; Gruendl, Robert A.; Looney, Leslie W.; Seale, Jonathan; Welty, Daniel E.; Hughes, Annie; Maddison, Sarah; Ott, Jürgen; Muller, Erik; Fukui, Yasuo; Kawamura, Akiko; Mizuno, Yoji; Pineda, Jorge L.; Bernard, Jean-Philippe; Paradis, Deborah; Henkel, Christian; Klein, Ulrich

    2011-01-01

    We present the properties of an extensive sample of molecular clouds in the Large Magellanic Cloud (LMC) mapped at 11 pc resolution in the CO(1-0) line. Targets were chosen based on a limiting CO flux and peak brightness as measured by the NANTEN survey. The observations were conducted with the ATNF Mopra Telescope as part of the Magellanic Mopra Assessment. We identify clouds as regions of connected CO emission and find that the distributions of cloud sizes, fluxes, and masses are sensitive to the choice of decomposition parameters. In all cases, however, the luminosity function of CO clouds is steeper than dN/dL∝L –2 , suggesting that a substantial fraction of mass is in low-mass clouds. A correlation between size and linewidth, while apparent for the largest emission structures, breaks down when those structures are decomposed into smaller structures. We argue that the correlation between virial mass and CO luminosity is the result of comparing two covariant quantities, with the correlation appearing tighter on larger scales where a size-linewidth relation holds. The virial parameter (the ratio of a cloud's kinetic to self-gravitational energy) shows a wide range of values and exhibits no clear trends with the CO luminosity or the likelihood of hosting young stellar object (YSO) candidates, casting further doubt on the assumption of virialization for molecular clouds in the LMC. Higher CO luminosity increases the likelihood of a cloud harboring a YSO candidate, and more luminous YSOs are more likely to be coincident with detectable CO emission, confirming the close link between giant molecular clouds and massive star formation.

  7. Molecular sieving through a graphene nanopore: non-equilibrium molecular dynamics simulation

    Institute of Scientific and Technical Information of China (English)

    Chengzhen Sun; Bofeng Bai

    2017-01-01

    Two-dimensional graphene nanopores have shown great promise as ultra-permeable molecular sieves based on their size-sieving effects.We design a nitrogen/hydrogen modified graphene nanopore and conduct a transient non-equilibrium molecular dynamics simulation on its molecular sieving effects.The distinct time-varying molecular crossing numbers show that this special nanopore can efficiently sieve CO2 and H2S molecules from CH4 molecules with high selectivity.By analyzing the molecular structure and pore functionalization-related molecular orientation and permeable zone in the nanopore,density distribution in the molecular adsorption layer on the graphene surface,as well as other features,the molecular sieving mechanisms of graphene nanopores are revealed.Finally,several implications on the design of highly-efficient graphene nanopores,especially for determining the porosity and chemical functionalization,as gas separation membranes are summarized based on the identified phenomena and mechanisms.

  8. 78 FR 37404 - Small Business Size Standards: Support Activities for Mining

    Science.gov (United States)

    2013-06-20

    ... assistance programs, SBA establishes small business size definitions (referred to as size standards) for... million should be the limit of a small business definition and anything larger than that, such as that SBA... Business Act (15 U.S.C. 632(a)) (Act) requires that small business size definitions vary to reflect...

  9. Effects of system size and cooling rate on the structure and properties of sodium borosilicate glasses from molecular dynamics simulations.

    Science.gov (United States)

    Deng, Lu; Du, Jincheng

    2018-01-14

    Borosilicate glasses form an important glass forming system in both glass science and technologies. The structure and property changes of borosilicate glasses as a function of thermal history in terms of cooling rate during glass formation and simulation system sizes used in classical molecular dynamics (MD) simulation were investigated with recently developed composition dependent partial charge potentials. Short and medium range structural features such as boron coordination, Si and B Q n distributions, and ring size distributions were analyzed to elucidate the effects of cooling rate and simulation system size on these structure features and selected glass properties such as glass transition temperature, vibration density of states, and mechanical properties. Neutron structure factors, neutron broadened pair distribution functions, and vibrational density of states were calculated and compared with results from experiments as well as ab initio calculations to validate the structure models. The results clearly indicate that both cooling rate and system size play an important role on the structures of these glasses, mainly by affecting the 3 B and 4 B distributions and consequently properties of the glasses. It was also found that different structure features and properties converge at different sizes or cooling rates; thus convergence tests are needed in simulations of the borosilicate glasses depending on the targeted properties. The results also shed light on the complex thermal history dependence on structure and properties in borosilicate glasses and the protocols in MD simulations of these and other glass materials.

  10. Effects of system size and cooling rate on the structure and properties of sodium borosilicate glasses from molecular dynamics simulations

    Science.gov (United States)

    Deng, Lu; Du, Jincheng

    2018-01-01

    Borosilicate glasses form an important glass forming system in both glass science and technologies. The structure and property changes of borosilicate glasses as a function of thermal history in terms of cooling rate during glass formation and simulation system sizes used in classical molecular dynamics (MD) simulation were investigated with recently developed composition dependent partial charge potentials. Short and medium range structural features such as boron coordination, Si and B Qn distributions, and ring size distributions were analyzed to elucidate the effects of cooling rate and simulation system size on these structure features and selected glass properties such as glass transition temperature, vibration density of states, and mechanical properties. Neutron structure factors, neutron broadened pair distribution functions, and vibrational density of states were calculated and compared with results from experiments as well as ab initio calculations to validate the structure models. The results clearly indicate that both cooling rate and system size play an important role on the structures of these glasses, mainly by affecting the 3B and 4B distributions and consequently properties of the glasses. It was also found that different structure features and properties converge at different sizes or cooling rates; thus convergence tests are needed in simulations of the borosilicate glasses depending on the targeted properties. The results also shed light on the complex thermal history dependence on structure and properties in borosilicate glasses and the protocols in MD simulations of these and other glass materials.

  11. Size Matters: Penis Size and Sexual Position in Gay Porn Profiles.

    Science.gov (United States)

    Brennan, Joseph

    2018-01-01

    This article combines qualitative and quantitative textual approaches to the representation of penis size and sexual position of performers in 10 of the most visited gay pornography Web sites currently in operation. Specifically, in excess of 6,900 performer profiles sourced from 10 commercial Web sites are analyzed. Textual analysis of the profile descriptions is combined with a quantitative representation of disclosed penis size and sexual position, which is presented visually by two figures. The figures confirm that these sites generally market themselves as featuring penises that are extraordinarily large and find a sample-wide correlation between smaller penis sizes (5-6.5 inches) and receptive sexual acts (bottoming), and larger (8.5-13 inches) with penetrative acts (topping). These observations are supported through the qualitative textual readings of how the performers are described on these popular sites, revealing the narratives and marketing strategies that shape the construction of popular porn brands, performers, and profitable fantasies.

  12. Measurements of the size dependence of the concentration of nonvolatile material in fog droplets

    Science.gov (United States)

    Ogren, J. A.; Noone, K. J.; Hallberg, A.; Heintzenberg, J.; Schell, D.; Berner, A.; Solly, I.; Kruisz, C.; Reischl, G.; Arends, B. G.; Wobrock, W.

    1992-11-01

    Measurements of the size dependence of the mass concentration of nonvolatile material dissolved and suspended in fog droplets were obtained with three complementary approaches, covering a size range from c. 1 50µm diameter: a counterflow virtual impactor, an eight-stage aerosol impactor, and a two-stage fogwater impactor. Concentrations were observed to decrease with size over the entire range, contrary to expectations of increasing concentrations at larger sizes. It is possible that the larger droplets had solute concentrations that increased with increasing size, but that the increase was too weak for the measurements to resolve. Future studies should consider the hypothesis that the droplets were coated with a surface-active substance that hindered their uptake of water.

  13. Observation of propane cluster size distributions during nucleation and growth in a Laval expansion

    Energy Technology Data Exchange (ETDEWEB)

    Ferreiro, Jorge J.; Chakrabarty, Satrajit; Schläppi, Bernhard; Signorell, Ruth [Laboratory of Physical Chemistry, ETH Zürich, Vladimir-Prelog Weg 2, CH-8093 Zürich (Switzerland)

    2016-12-07

    We report on molecular-level studies of the condensation of propane gas and propane/ethane gas mixtures in the uniform (constant pressure and temperature) postnozzle flow of Laval expansions using soft single-photon ionization by vacuum ultraviolet light and mass spectrometric detection. The whole process, from the nucleation to the growth to molecular aggregates of sizes of several nanometers (∼5 nm), can be monitored at the molecular level with high time-resolution (∼3 μs) for a broad range of pressures and temperatures. For each time, pressure, and temperature, a whole mass spectrum is recorded, which allows one to determine the critical cluster size range for nucleation as well as the kinetics and mechanisms of cluster-size specific growth. The detailed information about the size, composition, and population of individual molecular clusters upon condensation provides unique experimental data for comparison with future molecular-level simulations.

  14. Consequences of sex-specific growth on sibling competition in black-headed gulls : A sexually-size dimorphic species with scramble competition

    NARCIS (Netherlands)

    Mueller, Wendt; Groothuis, Ton G. G.; Dijkstra, Cor

    2007-01-01

    Biased mortality of the larger sex during the early developmental period has been reported for a number of size-dimorphic bird species. This can partly be explained by the fact that growing to larger size renders the larger sex more vulnerable to food shortage. However, since sibling rivalry is

  15. Food web structure shaped by habitat size and climate across a latitudinal gradient.

    Science.gov (United States)

    Romero, Gustavo Q; Piccoli, Gustavo C O; de Omena, Paula M; Gonçalves-Souza, Thiago

    2016-10-01

    Habitat size and climate are known to affect the trophic structure and dynamics of communities, but their interactive effects are poorly understood. Organisms from different trophic levels vary in terms of metabolic requirements and heat dissipation. Indeed, larger species such as keystone predators require more stable climatic conditions than their prey. Likewise, habitat size disproportionally affects large-sized predators, which require larger home ranges and are thus restricted to larger habitats. Therefore, food web structure in patchy ecosystems is expected to be shaped by habitat size and climate variations. Here we investigate this prediction using natural aquatic microcosm (bromeliad phytotelmata) food webs composed of litter resources (mainly detritus), detritivores, mesopredators, and top predators (damselflies). We surveyed 240 bromeliads of varying sizes (water retention capacity) across 12 open restingas in SE Brazil spread across a wide range of tropical latitudes (-12.6° to -27.6°, ca. 2,000 km) and climates (Δ mean annual temperature = 5.3°C). We found a strong increase in predator-to-detritivore mass ratio with habitat size, which was representative of a typical inverted trophic pyramid in larger ecosystems. However, this relationship was contingent among the restingas; slopes of linear models were steeper in more stable and favorable climates, leading to inverted trophic pyramids (and top-down control) being more pronounced in environments with more favorable climatic conditions. By contrast, detritivore-resource and mesopredator-detritivore mass ratios were not affected by habitat size or climate variations across latitudes. Our results highlight that the combined effects of habitat size, climate and predator composition are pivotal to understanding the impacts of multiple environmental factors on food web structure and dynamics. © 2016 by the Ecological Society of America.

  16. Is a larger refuge always better? Dispersal and dose in pesticide resistance evolution.

    Science.gov (United States)

    Takahashi, Daisuke; Yamanaka, Takehiko; Sudo, Masaaki; Andow, David A

    2017-06-01

    The evolution of resistance against pesticides is an important problem of modern agriculture. The high-dose/refuge strategy, which divides the landscape into treated and nontreated (refuge) patches, has proven effective at delaying resistance evolution. However, theoretical understanding is still incomplete, especially for combinations of limited dispersal and partially recessive resistance. We reformulate a two-patch model based on the Comins model and derive a simple quadratic approximation to analyze the effects of limited dispersal, refuge size, and dominance for high efficacy treatments on the rate of evolution. When a small but substantial number of heterozygotes can survive in the treated patch, a larger refuge always reduces the rate of resistance evolution. However, when dominance is small enough, the evolutionary dynamics in the refuge population, which is indirectly driven by migrants from the treated patch, mainly describes the resistance evolution in the landscape. In this case, for small refuges, increasing the refuge size will increase the rate of resistance evolution. Our analysis distils major driving forces from the model, and can provide a framework for understanding directional selection in source-sink environments. © 2017 The Author(s). Evolution published by Wiley Periodicals, Inc. on behalf of The Society for the Study of Evolution.

  17. A multifunctional role of trialkylbenzenes for the preparation of aqueous colloidal mesostructured/mesoporous silica nanoparticles with controlled pore size, particle diameter, and morphology

    Science.gov (United States)

    Yamada, Hironori; Ujiie, Hiroto; Urata, Chihiro; Yamamoto, Eisuke; Yamauchi, Yusuke; Kuroda, Kazuyuki

    2015-11-01

    Both the pore size and particle diameter of aqueous colloidal mesostructured/mesoporous silica nanoparticles (CMSS/CMPS) derived from tetrapropoxysilane were effectively and easily controlled by the addition of trialkylbenzenes (TAB). Aqueous highly dispersed CMPS with large pores were successfully obtained through removal of surfactants and TAB by a dialysis process. The pore size (from 4 nm to 8 nm) and particle diameter (from 50 nm to 380 nm) were more effectively enlarged by the addition of 1,3,5-triisopropylbenzene (TIPB) than 1,3,5-trimethylbenzene (TMB), and the enlargement did not cause the variation of the mesostructure and particle morphology. The larger molecular size and higher hydrophobicity of TIPB than TMB induce the incorporation of TIPB into micelles without the structural change. When TMB was used as TAB, the pore size of CMSS was also enlarged while the mesostructure and particle morphology were varied. Interestingly, when tetramethoxysilane and TIPB were used, CMSS with a very small particle diameter (20 nm) with concave surfaces and large mesopores were obtained, which may strongly be related to the initial nucleation of CMSS. A judicious choice of TAB and Si sources is quite important to control the mesostructure, size of mesopores, particle diameter, and morphology.Both the pore size and particle diameter of aqueous colloidal mesostructured/mesoporous silica nanoparticles (CMSS/CMPS) derived from tetrapropoxysilane were effectively and easily controlled by the addition of trialkylbenzenes (TAB). Aqueous highly dispersed CMPS with large pores were successfully obtained through removal of surfactants and TAB by a dialysis process. The pore size (from 4 nm to 8 nm) and particle diameter (from 50 nm to 380 nm) were more effectively enlarged by the addition of 1,3,5-triisopropylbenzene (TIPB) than 1,3,5-trimethylbenzene (TMB), and the enlargement did not cause the variation of the mesostructure and particle morphology. The larger molecular size

  18. 6 Tips for Managing Portion Size

    Science.gov (United States)

    Eating healthy is about enjoying your food while also managing portion size. Most people eat and drink more than their bodies need especially when they are served larger portions. So, choosing smaller portions to begin with is important for maintaining your overall health and well-being.

  19. Influence of size and temperature on the phase stability and thermophysical properties of anatase TiO2 nanoparticles: molecular dynamics simulation

    International Nuclear Information System (INIS)

    Okeke, George; Hammond, Robert B.; Joseph Antony, S.

    2013-01-01

    Nanoparticles have attracted the attention of researchers in a number of multidisciplinary fields as they possess enhanced structural and physical properties, which make them desirable to a wide range of industries. These enhancements have mostly been attributed to their large surface area-to-volume ratio. However, the effect of temperature on the structural and surface properties of nanoparticles of different sizes is still not well understood, an aspect addressed in the present work. Using molecular dynamics simulations, we have performed investigations on anatase TiO 2 nanoparticles with sizes ranging between 2 and 6 nm and at different temperatures. Structural and surface properties including surface energies are reported for the different nanoparticle sizes, temperature and simulation time step. Comparisons of surface energies for the different nanoparticle sizes show that surface energy increases to a maximum (optimum value) especially for temperatures between 300 and 1,500 K, as the particle size increases after which no further significant increase is observed. Studies conducted on the change of final structure with respect to the initial structure of the particles, revealed that atomic structural disordering is more visible at the surface layer compared to the bulk or core of the final structure. Further studies conducted on the sphericity of the nanoparticles showed that the particles became less spherical with increase in temperature.

  20. Only half right: species with female-biased sexual size dimorphism consistently break Rensch's rule.

    Directory of Open Access Journals (Sweden)

    Thomas J Webb

    2007-09-01

    Full Text Available Most animal species display Sexual Size Dimorphism (SSD: males and females consistently attain different sizes, most frequently with females being larger than males. However the selective mechanisms driving patterns of SSD remain controversial. 'Rensch's rule' proposes a general scaling phenomenon for all taxa, whereby SSD increases with average body size when males are larger than females, and decreases with body size when females are larger than males. Rensch's rule appears to be general in the former case, but there is little evidence for the rule when females are larger then males.Using comprehensive data for 1291 species of birds across 30 families, we find strong support for Rensch's rule in families where males are typically larger than females, but no overall support for the rule in families with female-biased SSD. Reviewing previous studies of a broad range of taxa (arthropods, reptiles, fish and birds showing predominantly female-biased SSD, we conclude that Rensch's conjecture is the exception rather than the rule in such species.The absence of consistent scaling of SSD in taxa with female-biased SSD, the most prevalent direction of dimorphism, calls into question previous general evolutionary explanations for Rensch's rule. We propose that, unlike several other ecological scaling relationships, Rensch's rule does not exist as an independent scaling phenomenon.

  1. Thymus size at 6 months of age and subsequent child mortality.

    Science.gov (United States)

    Garly, May-Lill; Trautner, Sisse Lecanda; Marx, Charlotte; Danebod, Kamilla; Nielsen, Jens; Ravn, Henrik; Martins, Cesário Lourenco; Balé, Carlito; Aaby, Peter; Lisse, Ida Maria

    2008-11-01

    To examine determinants of thymus size at age 6 months and investigate whether thymus size at this age is a determinant of subsequent mortality. Thymus size was measured by transsternal sonography in 923 6-month-old children participating in a measles vaccination trial in Guinea-Bissau. Thymus size was strongly associated with anthropometric measurements. Boys had larger thymuses than girls, controlling for anthropometry. Crying during sonography made the thymus appear smaller. Children who were not vaccinated with Bacille Calmette-Guérin (BCG) or were vaccinated with BCG in the preceding 4 weeks before inclusion into the study had larger thymuses. Children who had malaria or had been treated with chloroquine or Quinimax in the previous week before inclusion had smaller thymuses. Controlled for background factors associated with thymus size and mortality, small thymus size remained a strong and independent risk factor for mortality (hazard ratio = 0.31; 95% confidence interval = 0.18 to 0.52). Small thymus size at age 6 months is a strong risk factor for mortality. To prevent unnecessary deaths, it is important to identify preventable factors predisposing to small thymus size.

  2. Molecular Level Design Principle behind Optimal Sizes of Photosynthetic LH2 Complex: Taming Disorder through Cooperation of Hydrogen Bonding and Quantum Delocalization.

    Science.gov (United States)

    Jang, Seogjoo; Rivera, Eva; Montemayor, Daniel

    2015-03-19

    The light harvesting 2 (LH2) antenna complex from purple photosynthetic bacteria is an efficient natural excitation energy carrier with well-known symmetric structure, but the molecular level design principle governing its structure-function relationship is unknown. Our all-atomistic simulations of nonnatural analogues of LH2 as well as those of a natural LH2 suggest that nonnatural sizes of LH2-like complexes could be built. However, stable and consistent hydrogen bonding (HB) between bacteriochlorophyll and the protein is shown to be possible only near naturally occurring sizes, leading to significantly smaller disorder than for nonnatural ones. Extensive quantum calculations of intercomplex exciton transfer dynamics, sampled for a large set of disorder, reveal that taming the negative effect of disorder through a reliable HB as well as quantum delocalization of the exciton is a critical mechanism that makes LH2 highly functional, which also explains why the natural sizes of LH2 are indeed optimal.

  3. Molecular dynamics simulation studies of mid-size liquid n-Alkanes, C12–C160

    International Nuclear Information System (INIS)

    Kwon, Tae Woo; Lee, Song Hi

    2015-01-01

    In this study, we report the results of molecular dynamics simulations (MD) for model systems of mid-size liquid n-alkanes (C 12 –C 160 ) at several temperatures (⁓2700 K) in canonical ensembles to calculate structural and dynamic properties (viscosity η, self-diffusion constant D, and monomeric friction constant ζ). For the small n-alkanes for n ≤ 80, the chains are clearly ≥ 1, which leads to the conclusion that the liquid n-alkanes are far away from the Rouse regime, but for the n-alkanes for n ≥ 120, the chains are ⁓ 1 and they are Gaussian. It is found that the long chains of these n-alkanes at high temperatures show abnormalities in density, viscosity, and monomeric friction constant. The mass and temperature dependences of structural and dynamic properties (η, D, and ζ) are discussed

  4. ON THE RELATIVE SIZES OF PLANETS WITHIN KEPLER MULTIPLE-CANDIDATE SYSTEMS

    International Nuclear Information System (INIS)

    Ciardi, David R.; Fabrycky, Daniel C.; Ford, Eric B.; Ragozzine, Darin; Gautier, T. N. III; Howell, Steve B.; Lissauer, Jack J.; Rowe, Jason F.

    2013-01-01

    We present a study of the relative sizes of planets within the multiple-candidate systems discovered with the Kepler mission. We have compared the size of each planet to the size of every other planet within a given planetary system after correcting the sample for detection and geometric biases. We find that for planet pairs for which one or both objects are approximately Neptune-sized or larger, the larger planet is most often the planet with the longer period. No such size-location correlation is seen for pairs of planets when both planets are smaller than Neptune. Specifically, if at least one planet in a planet pair has a radius of ∼> 3 R ⊕ , 68% ± 6% of the planet pairs have the inner planet smaller than the outer planet, while no preferred sequential ordering of the planets is observed if both planets in a pair are smaller than ∼ ⊕ .

  5. Body size affects the strength of social interactions and spatial organization of a schooling fish (Pseudomugil signifer)

    Science.gov (United States)

    Romenskyy, Maksym; Herbert-Read, James E.; Ward, Ashley J. W.; Sumpter, David J. T.

    2017-04-01

    While a rich variety of self-propelled particle models propose to explain the collective motion of fish and other animals, rigorous statistical comparison between models and data remains a challenge. Plausible models should be flexible enough to capture changes in the collective behaviour of animal groups at their different developmental stages and group sizes. Here, we analyse the statistical properties of schooling fish (Pseudomugil signifer) through a combination of experiments and simulations. We make novel use of a Boltzmann inversion method, usually applied in molecular dynamics, to identify the effective potential of the mean force of fish interactions. Specifically, we show that larger fish have a larger repulsion zone, but stronger attraction, resulting in greater alignment in their collective motion. We model the collective dynamics of schools using a self-propelled particle model, modified to include varying particle speed and a local repulsion rule. We demonstrate that the statistical properties of the fish schools are reproduced by our model, thereby capturing a number of features of the behaviour and development of schooling fish.

  6. Size-dependent effects of low level cadmium and zinc exposure on the metabolome of the Asian clam, Corbicula fluminea

    International Nuclear Information System (INIS)

    Spann, Nicole; Aldridge, David C.; Griffin, Julian L.; Jones, Oliver A.H.

    2011-01-01

    Highlights: Small and large Corbicula fluminea were exposed to cadmium and zinc spiked sediment. Metabolomic changes in the freshwater clams were determined by NMR and GC–MS. Metabolic perturbations were related to amino acid and energy related metabolism. Small and large clams were differentiated by their metabolic composition. Size classes showed opposite responses to metal stress. - Abstract: The toxic effects of low level metal contamination in sediments are currently poorly understood. We exposed different sized Asian clams, Corbicula fluminea, to sediment spiked with environmentally relevant concentrations of either zinc, cadmium or a zinc–cadmium mixture for one week. This freshwater bivalve is well suited for sediment toxicity tests as it lives partly buried in the sediment and utilises sediment particles as a food resource. After one week, the whole tissue composition of low molecular weight metabolites was analysed by nuclear magnetic resonance spectroscopy (NMR) and gas chromatography–mass spectrometry (GC–MS). The condition index (ratio of tissue dry weight to volume inside the shell valves) was also measured. Small and large clams were clearly differentiated by their metabolic composition and the two size classes showed opposite responses to the mixture spiked sediment. No effects of zinc alone on the metabolome were found and cadmium only influenced the smaller size class. The main perturbations were seen in amino acid and energy metabolism, with small clams using amino acids as an energy resource and larger clams primarily drawing on their larger storage reserves of carbohydrates. Our study demonstrates that metabolomics is a useful technique to test for low level toxicity which does not manifest in mortality or condition index changes. The differing effects between the two size classes stress that it is important to consider age/size when conducting metabolomic and ecotoxicology assessments, since testing for the effects on only one size

  7. Size-dependent effects of low level cadmium and zinc exposure on the metabolome of the Asian clam, Corbicula fluminea

    Energy Technology Data Exchange (ETDEWEB)

    Spann, Nicole, E-mail: nicole.spann@web.de [Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ (United Kingdom); Aldridge, David C., E-mail: da113@cam.ac.uk [Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ (United Kingdom); Griffin, Julian L., E-mail: jlg40@mole.bio.cam.ac.uk [Sanger Building, Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA (United Kingdom); Jones, Oliver A.H., E-mail: o.jones@gmail.com [Sanger Building, Department of Biochemistry, University of Cambridge, 80 Tennis Court Road, Cambridge CB2 1GA (United Kingdom)

    2011-10-15

    Highlights: Small and large Corbicula fluminea were exposed to cadmium and zinc spiked sediment. Metabolomic changes in the freshwater clams were determined by NMR and GC-MS. Metabolic perturbations were related to amino acid and energy related metabolism. Small and large clams were differentiated by their metabolic composition. Size classes showed opposite responses to metal stress. - Abstract: The toxic effects of low level metal contamination in sediments are currently poorly understood. We exposed different sized Asian clams, Corbicula fluminea, to sediment spiked with environmentally relevant concentrations of either zinc, cadmium or a zinc-cadmium mixture for one week. This freshwater bivalve is well suited for sediment toxicity tests as it lives partly buried in the sediment and utilises sediment particles as a food resource. After one week, the whole tissue composition of low molecular weight metabolites was analysed by nuclear magnetic resonance spectroscopy (NMR) and gas chromatography-mass spectrometry (GC-MS). The condition index (ratio of tissue dry weight to volume inside the shell valves) was also measured. Small and large clams were clearly differentiated by their metabolic composition and the two size classes showed opposite responses to the mixture spiked sediment. No effects of zinc alone on the metabolome were found and cadmium only influenced the smaller size class. The main perturbations were seen in amino acid and energy metabolism, with small clams using amino acids as an energy resource and larger clams primarily drawing on their larger storage reserves of carbohydrates. Our study demonstrates that metabolomics is a useful technique to test for low level toxicity which does not manifest in mortality or condition index changes. The differing effects between the two size classes stress that it is important to consider age/size when conducting metabolomic and ecotoxicology assessments, since testing for the effects on only one size class makes

  8. Proteomic identification of gender molecular markers in Bothrops jararaca venom.

    Science.gov (United States)

    Zelanis, André; Menezes, Milene C; Kitano, Eduardo S; Liberato, Tarcísio; Tashima, Alexandre K; Pinto, Antonio F M; Sherman, Nicholas E; Ho, Paulo L; Fox, Jay W; Serrano, Solange M T

    2016-04-29

    Variation in the snake venom proteome is a well-documented phenomenon; however, sex-based variation in the venom proteome/peptidome is poorly understood. Bothrops jararaca shows significant sexual size dimorphism and here we report a comparative proteomic/peptidomic analysis of venoms from male and female specimens and correlate it with the evaluation of important venom features. We demonstrate that adult male and female venoms have distinct profiles of proteolytic activity upon fibrinogen and gelatin. These differences were clearly reflected in their different profiles of SDS-PAGE, two-dimensional electrophoresis and glycosylated proteins. Identification of differential protein bands and spots between male or female venoms revealed gender-specific molecular markers. However, the proteome comparison by in-solution trypsin digestion and label-free quantification analysis showed that the overall profiles of male and female venoms are similar at the polypeptide chain level but show striking variation regarding their attached carbohydrate moieties. The analysis of the peptidomes of male and female venoms revealed different contents of peptides, while the bradykinin potentiating peptides (BPPs) showed rather similar profiles. Furthermore we confirmed the ubiquitous presence of four BPPs that lack the C-terminal Q-I-P-P sequence only in the female venom as gender molecular markers. As a result of these studies we demonstrate that the sexual size dimorphism is associated with differences in the venom proteome/peptidome in B. jararaca species. Moreover, gender-based variations contributed by different glycosylation levels in toxins impact venom complexity. Bothrops jararaca is primarily a nocturnal and generalist snake species, however, it exhibits a notable ontogenetic shift in diet and in venom proteome upon neonate to adult transition. As is common in the Bothrops genus, B. jararaca shows significant sexual dimorphism in snout-vent length and weight, with females being

  9. Offspring fitness and individual optimization of clutch size

    Science.gov (United States)

    Both, C.; Tinbergen, J. M.; Noordwijk, A. J. van

    1998-01-01

    Within-year variation in clutch size has been claimed to be an adaptation to variation in the individual capacity to raise offspring. We tested this hypothesis by manipulating brood size to one common size, and predicted that if clutch size is individually optimized, then birds with originally large clutches have a higher fitness than birds with originally small clutches. No evidence was found that fitness was related to the original clutch size, and in this population clutch size is thus not related to the parental capacity to raise offspring. However, offspring from larger original clutches recruited better than their nest mates that came from smaller original clutches. This suggests that early maternal or genetic variation in viability is related to clutch size.

  10. Dolphin underwater bait-balling behaviors in relation to group and prey ball sizes.

    Science.gov (United States)

    Vaughn-Hirshorn, Robin L; Muzi, Elisa; Richardson, Jessica L; Fox, Gabriella J; Hansen, Lauren N; Salley, Alyce M; Dudzinski, Kathleen M; Würsig, Bernd

    2013-09-01

    We characterized dusky dolphin (Lagenorhynchus obscurus) feeding behaviors recorded on underwater video, and related behaviors to variation in prey ball sizes, dolphin group sizes, and study site (Argentina versus New Zealand, NZ). Herding behaviors most often involved dolphins swimming around the side or under prey balls, but dolphins in Argentina more often swam under prey balls (48% of passes) than did dolphins in NZ (34% of passes). This result may have been due to differences in group sizes between sites, since groups are larger in Argentina. Additionally, in NZ, group size was positively correlated with proportion of passes that occurred under prey balls (pdolphins in Argentina more often swam through prey balls (8% of attempts) than did dolphins in NZ (4% of attempts). This result may have been due to differences in prey ball sizes between sites, since dolphins fed on larger prey balls in Argentina (>74m(2)) than in NZ (maximum 33m(2)). Additionally, in NZ, dolphins were more likely to swim through prey balls to capture fish when they fed on larger prey balls (p=0.025). Copyright © 2013 Elsevier B.V. All rights reserved.

  11. Molecular clouds in M31 and M33

    International Nuclear Information System (INIS)

    Blitz, L.

    1985-01-01

    In order to determine the properties of the molecular clouds in nearby spiral galaxies, 49 H II regions in M31 and 6 H II regions in M33 were observed using the J = 1→0 transition of CO. Of these, 17 were detected in M31 and two in M33. For the CO detection in M31, = 0.14 K, = 12.5 km s -1 , and = 2.1 K km s -1 . The two detections in M33, which are toward the giant H II regions NGC 604 and NGC 595, are somewhat weaker than the mean values for clouds in M31, neither T(/sub R/ nor ΔV shows any gradient with galactic radius, but is a decreasing function of radius. The mean values of and are considerably larger than the values that would be obtained by extrapolating local giant molecular clouds to the distance of M31. It is suggested that most of the CO emission is from small clouds in the beam which overwhelm the emission from the giant molecular clouds. Some observational tests of this suggestion are proposed. Like the molecular clouds in the Milky Way, the giant molecular clouds in M31 appear to be tidally limited. In M33 the larger inclination angle would make the observed contribution from small molecular clouds less significant, which is consistent with the observations

  12. The Size Distribution of Stardust Injected into the ISM

    Science.gov (United States)

    Krueger, D.; Sedlmayr, E.

    1996-01-01

    A multi-component method for the description of the evolution of the grain size distribution in consideration of a size dependent grain drift and growth rate is applied in order to model dust driven winds around cool C-stars. Grain drift introduces several modifications concerning dust growth: on one hand the residence time in the region of efficient growth is reduced, on the other hand the growth efficiency is higher due to an increased collisional rate. For carbon grains the surface density of radical sites is increased, but on the other hand there is a reduction of the sticking efficiency of the growth species for drift velocities larger than a few km/s. It is found that the consideration of drift results in a considerable distortion of the size distribution as compared to the case of zero drift velocity. Generally, there are less, but larger grains if drift is included.

  13. Effects of Meaning and Symmetry on Judgments of Size

    DEFF Research Database (Denmark)

    Reber, Rolf; Christensen, Bo T.; Meier, Beat

    2014-01-01

    to be judged as larger than asymmetric numbers (e.g., 43). However, recent research found that symmetric numbers were judged to be smaller than asymmetric numbers. This finding suggests that the mechanisms underlying size judgments may differ in meaningful and meaningless materials. Supporting this notion, we...... showed in Experiment 1 that meaning increased judged size, whereas symmetry decreased judged size. In the next two experiments, we excluded several alternative explanations for the differences in size judgments between meaningful and meaningless materials in earlier studies. This finding contradicts...

  14. Size dependent thermal hysteresis in spin crossover nanoparticles reflected within a Monte Carlo based Ising-like model

    International Nuclear Information System (INIS)

    Atitoaie, Alexandru; Tanasa, Radu; Enachescu, Cristian

    2012-01-01

    Spin crossover compounds are photo-magnetic bistable molecular magnets with two states in thermodynamic competition: the diamagnetic low-spin state and paramagnetic high-spin state. The thermal transition between the two states is often accompanied by a wide hysteresis, premise for possible application of these materials as recording media. In this paper we study the influence of the system's size on the thermal hysteresis loops using Monte Carlo simulations based on an Arrhenius dynamics applied for an Ising like model with long- and short-range interactions. We show that using appropriate boundary conditions it is possible to reproduce both the drop of hysteresis width with decreasing particle size, the hysteresis shift towards lower temperatures and the incomplete transition, as in the available experimental data. The case of larger systems composed by several sublattices is equally treated reproducing the shrinkage of the hysteresis loop's width experimentally observed. - Highlights: ► A study concerning size effects in spin crossover nanoparticles hysteresis is presented. ► An Ising like model with short- and long-range interactions and Arrhenius dynamics is employed. ► In open boundary system the hysteresis width decreases with particle size. ► With appropriate environment, hysteresis loop is shifted towards lower temperature and transition is incomplete.

  15. Introgression of a Rare Haplotype from Southeastern Africa to Breed California Blackeyes with Larger Seeds

    Directory of Open Access Journals (Sweden)

    Mitchell R Lucas

    2015-03-01

    Full Text Available Seed size distinguishes most crops from their wild relatives and is an important quality trait for the grain legume cowpea. In order to breed cowpea varieties with larger seeds we introgressed a rare haplotype associated with large seeds at the Css-1 locus from an African buff seed type cultivar, IT82E-18 (18.5g/100 seeds, into a blackeye seed type cultivar, CB27 (22g/100 seed. Four RILs derived from these two parents were chosen for marker-assisted breeding based on SNP genotyping with a goal of stacking large seed haplotypes into a CB27 background. Foreground and background selection were performed during two cycles of backcrossing based on genome-wide SNP markers. The average seed size of introgression lines homozygous for haplotypes associated with large seeds was 28.7g/100 seed and 24.8g/100 seed for cycles 1 and 2, respectively. One cycle 1 introgression line with desirable seed quality was selfed for two generations to make families with very large seeds (28-35g/100 seeds. Field-based performance trials helped identify breeding lines that not only have large seeds but are also desirable in terms of yield, maturity, and plant architecture when compared to industry standards. A principal component analysis was used to explore the relationships between the parents relative to a core set of landraces and improved varieties based on high-density SNP data. The geographic distribution of haplotypes at the Css-1 locus suggest the haplotype associated with large seeds is unique to accessions collected from Southeastern Africa. Therefore this QTL has a strong potential to develop larger seeded varieties for other growing regions which is demonstrated in this work using a California pedigree.

  16. Acceleration of cluster and molecular ions by TIARA 3 MV tandem accelerator

    CERN Document Server

    Saitoh, Y; Tajima, S

    2000-01-01

    We succeeded in accelerating molecular and cluster ions (B sub 2 sub - sub 4 , C sub 2 sub - sub 1 sub 0 , O sub 2 , Al sub 2 sub - sub 4 , Si sub 2 sub - sub 4 , Cu sub 2 sub - sub 3 , Au sub 2 sub - sub 3 , LiF, and AlO) to MeV energies with high-intensity beam currents by means of a 3 MV tandem accelerator in the TIARA facility. These cluster ions were generated by a cesium sputter-type negative ion source. We tested three types of carbon sputter cathodes in which graphite powder was compressed with different pressures. The pressure difference affected the generating ratio of clusters generated to single atom ions extracted from the source and it appeared that the high-density cathode was suitable. We also investigated the optimum gas pressure for charge exchange in the tandem high-voltage terminal. Clusters of larger size tend to require lower pressure than do smaller ones. In addition, we were able to obtain doubly charged AlO molecular ions. (authors)

  17. Reestablishment of radiographic kidney size in Miniature Schnauzer dogs.

    Science.gov (United States)

    Sohn, Jungmin; Yun, Sookyung; Lee, Jeosoon; Chang, Dongwoo; Choi, Mincheol; Yoon, Junghee

    2017-01-10

    Kidney size may be altered in renal diseases, and the detection of kidney size alteration has diagnostic and prognostic values. We hypothesized that radiographic kidney size, the kidney length to the second lumbar vertebra (L2) length ratio, in normal Miniature Schnauzer dogs may be overestimated due to their shorter vertebral length. This study was conducted to evaluate radiographic and ultrasonographic kidney size and L2 length in clinically normal Miniature Schnauzers and other dog breeds to evaluate the effect of vertebral length on radiographic kidney size and to reestablish radiographic kidney size in normal Miniature Schnauzers. Abdominal radiographs and ultrasonograms from 49 Miniature Schnauzers and 54 other breeds without clinical evidence of renal disease and lumbar vertebral abnormality were retrospectively evaluated. Radiographic kidney size, in the Miniature Schnauzer (3.31 ± 0.26) was significantly larger than that in other breeds (2.94 ± 0.27). Relative L2 length, the L2 length to width ratio, in the Miniature Schnauzer (1.11 ± 0.06) was significantly shorter than that in other breeds (1.21 ± 0.09). However, ultrasonographic kidney sizes, kidney length to aorta diameter ratios, were within or very close to normal range both in the Miniature Schnauzer (6.75 ± 0.67) and other breeds (7.16 ± 1.01). Thus, Miniature Schnauzer dogs have breed-specific short vertebrae and consequently a larger radiographic kidney size, which was greater than standard reference in normal adult dogs. Care should be taken when evaluating radiographic kidney size in Miniature Schnauzers to prevent falsely diagnosed renomegaly.

  18. Sexual dimorphism in size, age, maturation, and growth characteristics of boarfish (Capros aper) in the Northeast Atlantic

    DEFF Research Database (Denmark)

    Hüssy, Karin; Coad, Julie Olivia; Farrell, Edward D.

    2012-01-01

    Sexual dimorphism in size, age, maturation, and growth characteristics of boarfish (Capros aper) in the Northeast Atlantic – ICES Journal of Marine Science, 69: 1729–1735.Boarfish (Capros aper) have, in recent years, become of increasing commercial importance due to their apparent increase...... stock with sexual dimorphism, where females are, on average, larger than males. No seasonal effects occur in size distribution and sex ratio, indicating that females and males stay together in shoals throughout the year. Females become increasingly dominant in abundance at larger sizes and older ages...... in abundance in the Northeast Atlantic. This study presents detailed biological information relevant to understanding stock structure and dynamics. Boarfish are a long-lived species that reach a maximum age of >30 years. The size distribution is skewed towards larger sizes, as expected from an unexploited...

  19. Plasticity in sexual size dimorphism and Rensch's rule in Mediterranean blennies (Blenniidae)

    NARCIS (Netherlands)

    Lengkeek, W.; Didderen, K.; Cote, I. M.; van der Zee, E. M.; Snoek, R. C.; Reynolds, J. D.

    2008-01-01

    Comparative analyses of sexual size dimorphism (SSD) across species have led to the discovery of Rensch's rule. This rule states that SSD increases with body size when males are the largest sex, but decreases with increasing size when females are larger. Within-species comparisons of SSD in fish are

  20. The impact of death awareness on sizes of self-representational objects.

    Science.gov (United States)

    McCabe, Simon; Vail, Kenneth E; Arndt, Jamie

    2018-01-01

    People seem to have a tendency to increase the relative size of self-representational objects. Prior research suggests that motivational factors may fuel that tendency, so the present research built from terror management theory to examine whether existential motivations - engendered by concerns about death - may have similar implications for self-relevant size biases. Specifically, across two studies (total N = 288), we hypothesized that reminders of death would lead participants to inflate the size of self-representational objects. Both studies suggested that relative to reminders of pain, mortality salience led participants to construct larger clay sculptures of themselves (vs. others; Study 1) and a larger ostensible video game avatar for the self (vs. others; Study 2). © 2017 The British Psychological Society.

  1. Sexual selection on male size drives the evolution of male-biased sexual size dimorphism via the prolongation of male development.

    Science.gov (United States)

    Rohner, Patrick T; Blanckenhorn, Wolf U; Puniamoorthy, Nalini

    2016-06-01

    Sexual size dimorphism (SSD) arises when the net effects of natural and sexual selection on body size differ between the sexes. Quantitative SSD variation between taxa is common, but directional intraspecific SSD reversals are rare. We combined micro- and macroevolutionary approaches to study geographic SSD variation in closely related black scavenger flies. Common garden experiments revealed stark intra- and interspecific variation: Sepsis biflexuosa is monomorphic across the Holarctic, while S. cynipsea (only in Europe) consistently exhibits female-biased SSD. Interestingly, S. neocynipsea displays contrasting SSD in Europe (females larger) and North America (males larger), a pattern opposite to the geographic reversal in SSD of S. punctum documented in a previous study. In accordance with the differential equilibrium model for the evolution of SSD, the intensity of sexual selection on male size varied between continents (weaker in Europe), whereas fecundity selection on female body size did not. Subsequent comparative analyses of 49 taxa documented at least six independent origins of male-biased SSD in Sepsidae, which is likely caused by sexual selection on male size and mediated by bimaturism. Therefore, reversals in SSD and the associated changes in larval development might be much more common and rapid and less constrained than currently assumed. © 2016 The Author(s). Evolution © 2016 The Society for the Study of Evolution.

  2. Does wine glass size influence sales for on-site consumption? A multiple treatment reversal design

    Directory of Open Access Journals (Sweden)

    Rachel Pechey

    2016-06-01

    Full Text Available Abstract Background Wine glass size can influence both perceptions of portion size and the amount poured, but its impact upon purchasing and consumption is unknown. This study aimed to examine the impact of wine glass size on wine sales for on-site consumption, keeping portion size constant. Methods In one establishment (with separate bar and restaurant areas in Cambridge, England, wine glass size (Standard; Larger; Smaller was changed over eight fortnightly periods. The bar and restaurant differ in wine sales by the glass vs. by the bottle (93 % vs. 63 % by the glass respectively. Results Daily wine volume purchased was 9.4 % (95 % CI: 1.9, 17.5 higher when sold in larger compared to standard-sized glasses. This effect seemed principally driven by sales in the bar area (bar: 14.4 % [3.3, 26.7]; restaurant: 8.2 % [−2.5, 20.1]. Findings were inconclusive as to whether sales were different with smaller vs. standard-sized glasses. Conclusions The size of glasses in which wine is sold, keeping the portion size constant, can affect consumption, with larger glasses increasing consumption. The hypothesised mechanisms for these differential effects need to be tested in a replication study. If replicated, policy implications could include considering glass size amongst alcohol licensing requirements. Trial registration ISRCTN registry: ISRCTN12018175 . Registered 12th May 2015.

  3. Cultural constructions of "obesity": understanding body size, social class and gender in Morocco.

    Science.gov (United States)

    Batnitzky, Adina K

    2011-01-01

    This article presents data from an in-depth qualitative study of overweight and diabetic women in Morocco, a North African country experiencing a rapid increase in obesity according to national statistics. This case study explores the heterogeneous relationship among health, culture and religion in Morocco by highlighting the relationship between the intricacies of women's everyday lives and their body sizes. My findings suggest that although the Body Mass Index (BMI) of adult women has been documented to have increased in Morocco along with other macroeconomic changes (i.e., increases in urbanization, etc.), "obesity" has yet to be universally medicalized in the Moroccan context. As such women do not generally utilize a medicalized concept of obesity in reference to their larger body sizes. Rather, cultural constructions of "obesity" are understood through cultural understandings of a larger body size, religious beliefs about health and illness, and the nature of women's religious participation. This stands in contrast to dominant accounts about the region that promote an overall veneration of a larger body size for women. Copyright © 2010 Elsevier Ltd. All rights reserved.

  4. Towards high-throughput molecular detection of Plasmodium: new approaches and molecular markers

    Directory of Open Access Journals (Sweden)

    Rogier Christophe

    2009-04-01

    molecular methods. Dot18S and CYTB, the new methods reported herein are highly sensitive, allow parasite DNA extraction as well as genus- and species-specific diagnosis of several hundreds of samples, and are amenable to high-throughput scaling up for larger sample sizes. Such methods provide novel information on malaria prevalence and epidemiology and are suited for active malaria detection. The usefulness of such sensitive malaria diagnosis tools, especially in low endemic areas where eradication plans are now on-going, is discussed in this paper.

  5. Estimating Search Engine Index Size Variability

    DEFF Research Database (Denmark)

    Van den Bosch, Antal; Bogers, Toine; De Kunder, Maurice

    2016-01-01

    One of the determining factors of the quality of Web search engines is the size of their index. In addition to its influence on search result quality, the size of the indexed Web can also tell us something about which parts of the WWW are directly accessible to the everyday user. We propose a novel...... method of estimating the size of a Web search engine’s index by extrapolating from document frequencies of words observed in a large static corpus of Web pages. In addition, we provide a unique longitudinal perspective on the size of Google and Bing’s indices over a nine-year period, from March 2006...... until January 2015. We find that index size estimates of these two search engines tend to vary dramatically over time, with Google generally possessing a larger index than Bing. This result raises doubts about the reliability of previous one-off estimates of the size of the indexed Web. We find...

  6. Properties of liquid clusters in large-scale molecular dynamics nucleation simulations

    International Nuclear Information System (INIS)

    Angélil, Raymond; Diemand, Jürg; Tanaka, Kyoko K.; Tanaka, Hidekazu

    2014-01-01

    We have performed large-scale Lennard-Jones molecular dynamics simulations of homogeneous vapor-to-liquid nucleation, with 10 9 atoms. This large number allows us to resolve extremely low nucleation rates, and also provides excellent statistics for cluster properties over a wide range of cluster sizes. The nucleation rates, cluster growth rates, and size distributions are presented in Diemand et al. [J. Chem. Phys. 139, 74309 (2013)], while this paper analyses the properties of the clusters. We explore the cluster temperatures, density profiles, potential energies, and shapes. A thorough understanding of the properties of the clusters is crucial to the formulation of nucleation models. Significant latent heat is retained by stable clusters, by as much as ΔkT = 0.1ε for clusters with size i = 100. We find that the clusters deviate remarkably from spherical—with ellipsoidal axis ratios for critical cluster sizes typically within b/c = 0.7 ± 0.05 and a/c = 0.5 ± 0.05. We examine cluster spin angular momentum, and find that it plays a negligible role in the cluster dynamics. The interfaces of large, stable clusters are thinner than planar equilibrium interfaces by 10%−30%. At the critical cluster size, the cluster central densities are between 5% and 30% lower than the bulk liquid expectations. These lower densities imply larger-than-expected surface areas, which increase the energy cost to form a surface, which lowers nucleation rates

  7. Determination of Flaw Size from Thermographic Data

    Science.gov (United States)

    Winfree, William P.; Howell, Patricia A.; Zalameda, Joseph N.

    2014-01-01

    Conventional methods for reducing the pulsed thermographic responses of delaminations tend to overestimate the size of the flaw. Since the heat diffuses in the plane parallel to the surface, the resulting temperature profile over the flaw is larger than the flaw. A variational method is presented for reducing the thermographic data to produce an estimated size for the flaw that is much closer to the true size of the flaw. The size is determined from the spatial thermal response of the exterior surface above the flaw and a constraint on the length of the contour surrounding the flaw. The technique is applied to experimental data acquired on a flat bottom hole composite specimen.

  8. Breaking Haller's rule: brain-body size isometry in a minute parasitic wasp.

    NARCIS (Netherlands)

    Woude, van der E.; Smid, H.M.; Chittka, L.; Huigens, M.E.

    2013-01-01

    Throughout the animal kingdom, Haller's rule holds that smaller individuals have larger brains relative to their body than larger-bodied individuals. Such brain-body size allometry is documented for all animals studied to date, ranging from small ants to the largest mammals. However, through

  9. New aids for the non-invasive prenatal diagnosis of achondroplasia: dysmorphic features, charts of fetal size and molecular confirmation using cell-free fetal DNA in maternal plasma

    NARCIS (Netherlands)

    Chitty, L. S.; Griffin, D. R.; Meaney, C.; Barrett, A.; Khalil, A.; Pajkrt, E.; Cole, T. J.

    2011-01-01

    To improve the prenatal diagnosis of achondroplasia by constructing charts of fetal size, defining frequency of sonographic features and exploring the role of non-invasive molecular diagnosis based on cell-free fetal deoxyribonucleic acid (DNA) in maternal plasma. Data on fetuses with a confirmed

  10. Genome Size, Molecular Phylogeny, and Evolutionary History of the Tribe Aquilarieae (Thymelaeaceae, the Natural Source of Agarwood

    Directory of Open Access Journals (Sweden)

    Azman H. Farah

    2018-05-01

    Full Text Available The tribe Aquilarieae of the family Thymelaeaceae consists of two genera, Aquilaria and Gyrinops, with a total of 30 species, distributed from northeast India, through southeast Asia and the south of China, to Papua New Guinea. They are an important botanical resource for fragrant agarwood, a prized product derived from injured or infected stems of these species. The aim of this study was to estimate the genome size of selected Aquilaria species and comprehend the evolutionary history of Aquilarieae speciation through molecular phylogeny. Five non-coding chloroplast DNA regions and a nuclear region were sequenced from 12 Aquilaria and three Gyrinops species. Phylogenetic trees constructed using combined chloroplast DNA sequences revealed relationships of the studied 15 members in Aquilarieae, while nuclear ribosomal DNA internal transcribed spacer (ITS sequences showed a paraphyletic relationship between Aquilaria species from Indochina and Malesian. We exposed, for the first time, the estimated divergence time for Aquilarieae speciation, which was speculated to happen during the Miocene Epoch. The ancestral split and biogeographic pattern of studied species were discussed. Results showed no large variation in the 2C-values for the five Aquilaria species (1.35–2.23 pg. Further investigation into the genome size may provide additional information regarding ancestral traits and its evolution history.

  11. Depicted serving size: cereal packaging pictures exaggerate serving sizes and promote overserving.

    Science.gov (United States)

    Tal, Aner; Niemann, Stina; Wansink, Brian

    2017-02-06

    Extensive work has focused on the effects of nutrition label information on consumer behavior on the one hand, and on the effects of packaging graphics on the other hand. However, little work has examined how serving suggestion depictions - graphics relating to serving size - influence the quantity consumers serve themselves. The current work examines the prevalence of exaggerated serving size depictions on product packaging (study 1) and its effects on food serving in the context of cereal (study 2). Study 1 was an observational field survey of cereal packaging. Study 2 was a mixed experimental cross-sectional design conducted at a U.S. university, with 51 student participants. Study 1 coded 158 US breakfast cereals and compared the serving sizes depicted on the front of the box with the suggested serving size stated on the nutrition facts panel. Study 2 measured the amount of cereal poured from exaggerated or accurate serving size depictions. Study 1 compared average servings via t-tests. Study 2 used a mixed model with cereal type as the repeated measure and a compound symmetry covariance matrix. Study 1 demonstrated that portion size depictions on the front of 158 cereal boxes were 65.84% larger (221 vs. 134 calories) than the recommended portions on nutrition facts panels of those cereals. Study 2 showed that boxes that depicted exaggerated serving sizes led people to pour 20% more cereal compared to pouring from modified boxes that depicted a single-size portion of cereal matching suggested serving size. This was 45% over the suggested serving size. Biases in depicted serving size depicted on cereal packaging are prevalent in the marketplace. Such biases may lead to overserving, which may consequently lead to overeating. Companies should depict the recommended serving sizes, or otherwise indicate that the depicted portion represents an exaggerated serving size.

  12. Depicted serving size: cereal packaging pictures exaggerate serving sizes and promote overserving

    Directory of Open Access Journals (Sweden)

    Aner Tal

    2017-02-01

    Full Text Available Abstract Background Extensive work has focused on the effects of nutrition label information on consumer behavior on the one hand, and on the effects of packaging graphics on the other hand. However, little work has examined how serving suggestion depictions - graphics relating to serving size - influence the quantity consumers serve themselves. The current work examines the prevalence of exaggerated serving size depictions on product packaging (study 1 and its effects on food serving in the context of cereal (study 2. Methods Study 1 was an observational field survey of cereal packaging. Study 2 was a mixed experimental cross-sectional design conducted at a U.S. university, with 51 student participants. Study 1 coded 158 US breakfast cereals and compared the serving sizes depicted on the front of the box with the suggested serving size stated on the nutrition facts panel. Study 2 measured the amount of cereal poured from exaggerated or accurate serving size depictions. Study 1 compared average servings via t-tests. Study 2 used a mixed model with cereal type as the repeated measure and a compound symmetry covariance matrix. Results Study 1 demonstrated that portion size depictions on the front of 158 cereal boxes were 64.7% larger (221 vs. 134 calories than the recommended portions on nutrition facts panels of those cereals. Study 2 showed that boxes that depicted exaggerated serving sizes led people to pour 17.8% more cereal compared to pouring from modified boxes that depicted a single-size portion of cereal matching suggested serving size. This was 42% over the suggested serving size. Conclusions Biases in depicted serving size depicted on cereal packaging are prevalent in the marketplace. Such biases may lead to overserving, which may consequently lead to overeating. Companies should depict the recommended serving sizes, or otherwise indicate that the depicted portion represents an exaggerated serving size.

  13. 7 CFR 52.1851 - Sizes of raisins with seeds-layer or cluster.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Sizes of raisins with seeds-layer or cluster. 52.1851...-Raisins with Seeds § 52.1851 Sizes of raisins with seeds—layer or cluster. The size of Layer or Cluster... measurement as applicable to layer or cluster raisins with seeds are: (a) 3 Crown size or larger. “3 Crown...

  14. Different Amounts of DNA in Newborn Cells of Escherichia coli Preclude a Role for the Chromosome in Size Control According to the "Adder" Model.

    Science.gov (United States)

    Huls, Peter G; Vischer, Norbert O E; Woldringh, Conrad L

    2018-01-01

    According to the recently-revived adder model for cell size control, newborn cells of Escherichia coli will grow and divide after having added a constant size or length, ΔL , irrespective of their size at birth. Assuming exponential elongation, this implies that large newborns will divide earlier than small ones. The molecular basis for the constant size increment is still unknown. As DNA replication and cell growth are coordinated, the constant ΔL could be based on duplication of an equal amount of DNA, ΔG , present in newborn cells. To test this idea, we measured amounts of DNA and lengths of nucleoids in DAPI-stained cells growing in batch culture at slow and fast rates. Deeply-constricted cells were divided in two subpopulations of longer and shorter lengths than average; these were considered to represent large and small prospective daughter cells, respectively. While at slow growth, large and small prospective daughter cells contained similar amounts of DNA, fast growing cells with multiforked replicating chromosomes, showed a significantly higher amount of DNA (20%) in the larger cells. This observation precludes the hypothesis that Δ L is based on the synthesis of a constant ΔG . Growth curves were constructed for siblings generated by asymmetric division and growing according to the adder model. Under the assumption that all cells at the same growth rate exhibit the same time between initiation of DNA replication and cell division (i.e., constant C+D -period), the constructions predict that initiation occurs at different sizes ( Li ) and that, at fast growth, large newborn cells transiently contain more DNA than small newborns, in accordance with the observations. Because the state of segregation, measured as the distance between separated nucleoids, was found to be more advanced in larger deeply-constricted cells, we propose that in larger newborns nucleoid separation occurs faster and at a shorter length, allowing them to divide earlier. We propose

  15. Molecular Structural Transformation of 2:1 Clay Minerals by a Constant-Pressure Molecular Dynamics Simulation Method

    International Nuclear Information System (INIS)

    Wang, J.; Gutierre, M.S.

    2010-01-01

    This paper presents results of a molecular dynamics simulation study of dehydrated 2:1 clay minerals using the Parrinello-Rahman constant-pressure molecular dynamics method. The method is capable of simulating a system under the most general applied stress conditions by considering the changes of MD cell size and shape. Given the advantage of the method, it is the major goal of the paper to investigate the influence of imposed cell boundary conditions on the molecular structural transformation of 2:1 clay minerals under different normal pressures. Simulation results show that the degrees of freedom of the simulation cell (i.e., whether the cell size or shape change is allowed) determines the final equilibrated crystal structure of clay minerals. Both the MD method and the static method have successfully revealed unforeseen structural transformations of clay minerals upon relaxation under different normal pressures. It is found that large shear distortions of clay minerals occur when full allowance is given to the cell size and shape change. A complete elimination of the interlayer spacing is observed in a static simulation. However, when only the cell size change is allowed, interlayer spacing is retained, but large internal shear stresses also exist.

  16. Molecular dynamics simulations and docking enable to explore the biophysical factors controlling the yields of engineered nanobodies

    Science.gov (United States)

    Soler, Miguel A.; De Marco, Ario; Fortuna, Sara

    2016-10-01

    Nanobodies (VHHs) have proved to be valuable substitutes of conventional antibodies for molecular recognition. Their small size represents a precious advantage for rational mutagenesis based on modelling. Here we address the problem of predicting how Camelidae nanobody sequences can tolerate mutations by developing a simulation protocol based on all-atom molecular dynamics and whole-molecule docking. The method was tested on two sets of nanobodies characterized experimentally for their biophysical features. One set contained point mutations introduced to humanize a wild type sequence, in the second the CDRs were swapped between single-domain frameworks with Camelidae and human hallmarks. The method resulted in accurate scoring approaches to predict experimental yields and enabled to identify the structural modifications induced by mutations. This work is a promising tool for the in silico development of single-domain antibodies and opens the opportunity to customize single functional domains of larger macromolecules.

  17. Microbe-associated molecular pattern (MAMP) signatures, synergy, size and charge

    DEFF Research Database (Denmark)

    Aslam, Shazia N.; Erbs, Gitte; Morrissey, Kate L.

    2009-01-01

    Triggering of defences by microbes has mainly been investigated using single elicitors or microbe-associated molecular patterns (MAMPs), but MAMPs are released in planta as complex mixtures together with endogenous oligogalacturonan (OGA) elicitor. We investigated the early responses in Arabidops...

  18. Molecular dynamics simulation, ab initio calculation, and size-selected anion photoelectron spectroscopy study of initial hydration processes of calcium chloride.

    Science.gov (United States)

    He, Zhili; Feng, Gang; Yang, Bin; Yang, Lijiang; Liu, Cheng-Wen; Xu, Hong-Guang; Xu, Xi-Ling; Zheng, Wei-Jun; Gao, Yi Qin

    2018-06-14

    To understand the initial hydration processes of CaCl 2 , we performed molecular simulations employing the force field based on the theory of electronic continuum correction with rescaling. Integrated tempering sampling molecular dynamics were combined with ab initio calculations to overcome the sampling challenge in cluster structure search and refinement. The calculated vertical detachment energies of CaCl 2 (H 2 O) n - (n = 0-8) were compared with the values obtained from photoelectron spectra, and consistency was found between the experiment and computation. Separation of the Cl-Ca ion pair is investigated in CaCl 2 (H 2 O) n - anions, where the first Ca-Cl ionic bond required 4 water molecules, and both Ca-Cl bonds are broken when the number of water molecules is larger than 7. For neutral CaCl 2 (H 2 O) n clusters, breaking of the first Ca-Cl bond starts at n = 5, and 8 water molecules are not enough to separate the two ion pairs. Comparing with the observations on magnesium chloride, it shows that separating one ion pair in CaCl 2 (H 2 O) n requires fewer water molecules than those for MgCl 2 (H 2 O) n . Coincidentally, the solubility of calcium chloride is higher than that of magnesium chloride in bulk solutions.

  19. Contrasted patterns of molecular evolution in dominant and recessive self-incompatibility haplotypes in Arabidopsis.

    Directory of Open Access Journals (Sweden)

    Pauline M Goubet

    Full Text Available Self-incompatibility has been considered by geneticists a model system for reproductive biology and balancing selection, but our understanding of the genetic basis and evolution of this molecular lock-and-key system has remained limited by the extreme level of sequence divergence among haplotypes, resulting in a lack of appropriate genomic sequences. In this study, we report and analyze the full sequence of eleven distinct haplotypes of the self-incompatibility locus (S-locus in two closely related Arabidopsis species, obtained from individual BAC libraries. We use this extensive dataset to highlight sharply contrasted patterns of molecular evolution of each of the two genes controlling self-incompatibility themselves, as well as of the genomic region surrounding them. We find strong collinearity of the flanking regions among haplotypes on each side of the S-locus together with high levels of sequence similarity. In contrast, the S-locus region itself shows spectacularly deep gene genealogies, high variability in size and gene organization, as well as complete absence of sequence similarity in intergenic sequences and striking accumulation of transposable elements. Of particular interest, we demonstrate that dominant and recessive S-haplotypes experience sharply contrasted patterns of molecular evolution. Indeed, dominant haplotypes exhibit larger size and a much higher density of transposable elements, being matched only by that in the centromere. Overall, these properties highlight that the S-locus presents many striking similarities with other regions involved in the determination of mating-types, such as sex chromosomes in animals or in plants, or the mating-type locus in fungi and green algae.

  20. Comparison of feeding behavior between two different-sized groups of Japanese macaques (Macaca fuscata yakui).

    Science.gov (United States)

    Kurihara, Yosuke; Hanya, Goro

    2015-05-13

    Group-living animals face intragroup scramble and intergroup contest competitions. Many studies have shown that larger groups bear the costs of intragroup scramble competition, which negatively affects the reproductive success of females. Unlike most primate species, Japanese macaques in the Yakushima coastal forest show increased reproductive success with group size. However, it remains unclear how group size affects the behavior of macaques. The present study examined the effects of group size on the feeding behavior of Japanese macaques in the Yakushima coastal forest. We investigated 9-13 adult females from two different-sized groups via focal animal sampling during October 2012-August 2013. We compared the feeding behavior, including patch use, between the two groups. The larger group had a larger home range and spent more time feeding, especially on mature leaves. This suggests that intragroup feeding competition should be more intense in the larger group than in the smaller group. The feeding of mature leaves might enable the larger group to increase the number of co-feeding individuals. Contrary to the predictions that the larger group travels longer distances and spends more time moving, the smaller group traveled longer distances, and spent more time moving, although the number of visited patches did not differ between the two groups. The immediate consequences of the loss of inter-group encounters could accumulate as daily travel costs, considering that group size is associated with inter-group dominance and that intergroup aggressive encounters occur frequently in the Yakushima coastal forest. This suggests that the smaller group has increased travel costs as a result of intergroup contest competition, which leads to decline in reproductive success. Am. J. Primatol. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  1. Age- and size-dependent mating performance and fertility in a pelagic copepod, Temora longicornis

    DEFF Research Database (Denmark)

    Sichlau, Mie Hylstofte; Kiørboe, Thomas

    2011-01-01

    Prepress abstract: In many species, size and age have been shown to be strong determinants of the reproductive success for both sexes. Here we examine age- and size dependent reproductive performance (egg- and sperm production, mating success) in a pelagic copepod. Compared to smaller males, larger...... males produce larger spermatophores containing more spermatozoa, and fertilize a larger fraction of available females. Females mating with large males produce more offspring than those mating with small males. Similarly, large females have higher egg production rates as well as a higher life-time egg...... fertilize females for only about eight days after they mature. The strong size- and age-dependent fertility observed in this species is conducive to the development of sexual selection via mate choice for young and large partners, as has been shown in one other copepod species...

  2. Import Penetration, Export Orientation and Plant Size in Indonesian Manufacturing

    OpenAIRE

    Sadayuki TAKII

    2014-01-01

    This paper empirically examines differential impacts of globalisation on plant size among plants with different characteristics, including initial plant size, import and export status, and ownership. After accounting for other characteristics, results of this analysis suggest that both import penetration and export orientation do not have differential impacts on the size of larger and smaller plants. This is contrary to fears that only relatively large plants can benefit from globalisation wh...

  3. Prognostic Importance of Small Prostate Size in Men Receiving Definitive Prostate Brachytherapy

    International Nuclear Information System (INIS)

    Taira, Al V.; Merrick, Gregory S.; Galbreath, Robert W.; Butler, Wayne M.; Adamovich, Edward; Wallner, Kent E.

    2012-01-01

    Purpose: To assess whether small prostate size is an adverse prognostic factor in men undergoing brachytherapy in the same manner in which it seems to be for men undergoing radical prostatectomy. Methods and Materials: From April 1995 to June 2008, 2024 patients underwent brachytherapy by a single brachytherapist. Median follow-up was 7.4 years. The role of small prostate size (≤20 cm 3 ) as a prognostic factor for biochemical progression-free survival, cause-specific survival, and all-cause mortality was investigated. The differences in survival between men with small and larger prostates were compared using Kaplan-Meier curves and log-rank tests. Results: Median prostate size for the entire cohort was 32.7 cm 3 . For the 167 men with small prostates, median prostate size was 17.4 cm 3 . There was no difference in biochemical progression-free survival (95.2% vs 96.2%, P=.603), cause-specific survival (97.7% vs 98.3%, P=.546), or all-cause mortality (78.0% vs 77.2%, P=.838) at 10 years for men with small prostates compared with men with larger prostates. On univariate and multivariate analysis, small prostate size was not associated with any of the primary outcome measures. Conclusion: Men with small prostates treated with brachytherapy have excellent outcomes and are at no higher risk of treatment failure than men with larger glands. High-quality implants with adequate margins seem sufficient to address the increased adverse risk factors associated with small prostate size.

  4. Big bees do a better job: intraspecific size variation influences pollination effectiveness

    Directory of Open Access Journals (Sweden)

    Pat Willmer

    2014-09-01

    Full Text Available 1. Bumblebees (Bombus spp. are efficient pollinators of many flowering plants, yet the pollen deposition performance of individual bees has not been investigated. Worker bumblebees exhibit large intraspecific and intra-nest size variation, in contrast with other eusocial bees; and their size influences collection and deposition of pollen grains. 2. Laboratory studies with B. terrestris workers and Vinca minor flowers showed that pollination effectiveness PE, as measured from pollen grains deposited on stigmas in single visits (SVD, was significantly positively related to bee size; larger bees deposited more grains, while the smallest individuals, with proportionally shorter tongues, were unable to collect or deposit pollen in these flowers. Individuals did not increase their pollen deposition over time, so handling experience does not influence SVD in Vinca minor. 3. Field studies using Geranium sanguineum and Echium vulgare, and multiple visiting species, confirmed that individual size affects SVD. All bumblebee species showed positive SVD/size effects, though even the smallest individuals did deposit pollen. Apis with its limited size variation showed no such detectable effect when visiting Geranium flowers. Two abundant hoverfly species also showed size effects, particularly when feeding for nectar on Echium. 4. Mean size of foragers also varied diurnally, with larger individuals active earlier and later, so that pollination effectiveness varies through a day; flowers routinely pollinated by bees may best be served by early morning dehiscence and visits from larger individuals. 5. Thus, while there are well-documented species-level variations in pollination effectiveness, the fine-scale individual differences between foragers should also be taken into account when assessing the reproductive outputs of biotically-pollinated plants.

  5. Effect of meal size and body size on specific dynamic action and gastric processing in decapod crustaceans.

    Science.gov (United States)

    McGaw, Iain J; Curtis, Daniel L

    2013-11-01

    Meal size and animal size are important factors affecting the characteristics of the specific dynamic action (SDA) response across a variety of taxa. The effects of these two variables on the SDA of decapod crustaceans are based on just a couple of articles, and are not wholly consistent with the responses reported for other aquatic ectotherms. Therefore, the effects of meal size and animal size on the characteristics of SDA response were investigated in a variety of decapod crustaceans from different families. A 6 fold increase in meal size (0.5%-3% body mass) resulted a pronounced increase in the duration of increased oxygen consumption, resulting in an increase in the SDA of Callinectes sapidus, Cancer gracilis, Hemigrapsus nudus, Homarus americanus, Pugettia producta and Procambarus clarkii. Unlike many other aquatic ectotherms a substantial increase between meal sizes was required, with meal size close to their upper feeding limit (3% body mass), before changes were evident. In many organisms increases in both duration and scope contribute to the overall SDA, here changes in scope as a function of meal size were weak, suggesting that a similar amount of energy is required to upregulate gastric processes, regardless of meal size. The SDA characteristics were less likely to be influenced by the size of the animal, and there was no difference in the SDA (kJ) as a function of size in H. americanus or Cancer irroratus when analysed as mass specific values. In several fish species characteristics of the SDA response are more closely related to the transit times of food, rather than the size of a meal. To determine if a similar trend occurred in crustaceans, the transit rates of different sized meals were followed through the digestive system using a fluoroscope. Although there was a trend towards larger meals taking longer to pass through the gut, this was only statistically significant for P. clarkii. There were some changes in transit times as a function of animal

  6. ChemCam Passive Sky Spectroscopy at Gale Crater, Mars: Interannual Variability in Dust Aerosol Particle Size, Missing Water Vapor, and the Molecular Oxygen Problem

    Science.gov (United States)

    McConnochie, T. H.; Smith, M. D.; Wolff, M. J.; Bender, S. C.; Lemmon, M. T.; Wiens, R. C.; Maurice, S.; Gasnault, O.; Lasue, J.; Meslin, P. Y.; Harri, A. M.; Genzer, M.; Kemppinen, O.; Martinez, G.; DeFlores, L. P.; Blaney, D. L.; Johnson, J. R.; Bell, J. F., III; Trainer, M. G.; Lefèvre, F.; Atreya, S. K.; Mahaffy, P. R.; Wong, M. H.; Franz, H. B.; Guzewich, S.; Villanueva, G. L.; Khayat, A. S.

    2017-12-01

    The Mars Science Laboratory's (MSL) ChemCam spectrometer measures atmospheric aerosol properties and gas abundances by operating in passive mode and observing scattered sky light at two different elevation angles. We have previously [e. g. 1, 2] presented the methodology and results of these ChemCam Passive Sky observations. Here we will focus on three of the more surprising results that we have obtained: (1) depletion of the column water vapor at Gale Crater relative to that of the surrounding region combined with a strong enhancement of the local column water vapor relative to pre-dawn in-situ measurements, (2) an interannual change in the effective particle size of dust aerosol during the aphelion season, and (3) apparent seasonal and interannual variability in molecular oxygen that differs significantly from the expected behavior of a non-condensable trace gas and differs significantly from global climate model expectations. The ChemCam passive sky water vapor measurements are quite robust but their interpretation depends on the details of measurements as well as on the types of water vapor vertical distributions that can be produced by climate models. We have a high degree of confidence in the dust particle size changes but since aerosol results in general are subject to a variety of potential systematic effects our particle size results would benefit from confirmation by other techniques [c.f. 3]. For the ChemCam passive sky molecular oxygen results we are still working to constrain the uncertainties well enough to confirm the observed surprising behavior, motivated by similarly surprising atmospheric molecular oxygen variability observed by MSL's Sample Analysis at Mars (SAM) instrument [4]. REFERENCES: [1] McConnochie, et al. (2017), Icarus (submitted). [2] McConnochie, et al. (2017), abstract # 3201, The 6th International Workshop on the Mars Atmosphere: Granada, Spain. [3] Vicente-Retortillo et al. (2017), GRL, 44. [4] Trainer et al. (2017), 2017 AGU Fall

  7. THE MASSIVE SATELLITE POPULATION OF MILKY-WAY-SIZED GALAXIES

    International Nuclear Information System (INIS)

    Rodríguez-Puebla, Aldo; Avila-Reese, Vladimir; Drory, Niv

    2013-01-01

    Several occupational distributions for satellite galaxies more massive than m * ≈ 4 × 10 7 M ☉ around Milky-Way (MW)-sized hosts are presented and used to predict the internal dynamics of these satellites as a function of m * . For the analysis, a large galaxy group mock catalog is constructed on the basis of (sub)halo-to-stellar mass relations fully constrained with currently available observations, namely the galaxy stellar mass function decomposed into centrals and satellites, and the two-point correlation functions at different masses. We find that 6.6% of MW-sized galaxies host two satellites in the mass range of the Small and Large Magellanic Clouds (SMC and LMC, respectively). The probabilities of the MW-sized galaxies having one satellite equal to or larger than the LMC, two satellites equal to or larger than the SMC, or three satellites equal to or larger than Sagittarius (Sgr) are ≈0.26, 0.14, and 0.14, respectively. The cumulative satellite mass function of the MW, N s (≥m * ) , down to the mass of the Fornax dwarf is within the 1σ distribution of all the MW-sized galaxies. We find that MW-sized hosts with three satellites more massive than Sgr (as the MW) are among the most common cases. However, the most and second most massive satellites in these systems are smaller than the LMC and SMC by roughly 0.7 and 0.8 dex, respectively. We conclude that the distribution N s (≥m * ) for MW-sized galaxies is quite broad, the particular case of the MW being of low frequency but not an outlier. The halo mass of MW-sized galaxies correlates only weakly with N s (≥m * ). Then, it is not possible to accurately determine the MW halo mass by means of its N s (≥m * ); from our catalog, we constrain a lower limit of 1.38 × 10 12 M ☉ at the 1σ level. Our analysis strongly suggests that the abundance of massive subhalos should agree with the abundance of massive satellites in all MW-sized hosts, i.e., there is not a missing (massive) satellite problem

  8. Investigation of active vibration drilling using acoustic emission and cutting size analysis

    Directory of Open Access Journals (Sweden)

    Yingjian Xiao

    2018-04-01

    Full Text Available This paper describes an investigation of active bit vibration on the penetration mechanisms and bit-rock interaction for drilling with a diamond impregnated coring bit. A series of drill-off tests (DOTs were conducted where the drilling rate-of-penetration (ROP was measured at a series of step-wise increasing static bit thrusts or weight-on-bits (WOBs. Two active DOTs were conducted by applying 60 Hz axial vibration at the bit-rock interface using an electromagnetic vibrating table mounted underneath the drilling samples, and a passive DOT was conducted where the bit was allowed to vibrate naturally with lower amplitude due to the compliance of the drilling sample mountings. During drilling, an acoustic emission (AE system was used to record the AE signals generated by the diamond cutter penetration and the cuttings were collected for grain size analysis. The instrumented drilling system recorded the dynamic motions of the bit-rock interface using a laser displacement sensor, a load cell, and an LVDT (linear variable differential transformer recorded the dynamic WOB and the ROP, respectively. Calibration with the drilling system showed that rotary speed was approximately the same at any given WOB, facilitating comparison of the results at the same WOB. Analysis of the experimental results shows that the ROP of the bit at any given WOB increased with higher amplitude of axial bit-rock vibration, and the drill cuttings increased in size with a higher ROP. Spectral analysis of the AEs indicated that the higher ROP and larger cutting size were correlated with a higher AE energy and a lower AE frequency. This indicated that larger fractures were being created to generate larger cutting size. Overall, these results indicate that a greater magnitude of axial bit-rock vibration produces larger fractures and generates larger cuttings which, at the same rotary speed, results in a higher ROP. Keywords: Active bit vibration, Diamond coring drilling, Drill

  9. Sample size determination for mediation analysis of longitudinal data.

    Science.gov (United States)

    Pan, Haitao; Liu, Suyu; Miao, Danmin; Yuan, Ying

    2018-03-27

    Sample size planning for longitudinal data is crucial when designing mediation studies because sufficient statistical power is not only required in grant applications and peer-reviewed publications, but is essential to reliable research results. However, sample size determination is not straightforward for mediation analysis of longitudinal design. To facilitate planning the sample size for longitudinal mediation studies with a multilevel mediation model, this article provides the sample size required to achieve 80% power by simulations under various sizes of the mediation effect, within-subject correlations and numbers of repeated measures. The sample size calculation is based on three commonly used mediation tests: Sobel's method, distribution of product method and the bootstrap method. Among the three methods of testing the mediation effects, Sobel's method required the largest sample size to achieve 80% power. Bootstrapping and the distribution of the product method performed similarly and were more powerful than Sobel's method, as reflected by the relatively smaller sample sizes. For all three methods, the sample size required to achieve 80% power depended on the value of the ICC (i.e., within-subject correlation). A larger value of ICC typically required a larger sample size to achieve 80% power. Simulation results also illustrated the advantage of the longitudinal study design. The sample size tables for most encountered scenarios in practice have also been published for convenient use. Extensive simulations study showed that the distribution of the product method and bootstrapping method have superior performance to the Sobel's method, but the product method was recommended to use in practice in terms of less computation time load compared to the bootstrapping method. A R package has been developed for the product method of sample size determination in mediation longitudinal study design.

  10. Rapid Convergence of Energy and Free Energy Profiles with Quantum Mechanical Size in Quantum Mechanical-Molecular Mechanical Simulations of Proton Transfer in DNA.

    Science.gov (United States)

    Das, Susanta; Nam, Kwangho; Major, Dan Thomas

    2018-03-13

    In recent years, a number of quantum mechanical-molecular mechanical (QM/MM) enzyme studies have investigated the dependence of reaction energetics on the size of the QM region using energy and free energy calculations. In this study, we revisit the question of QM region size dependence in QM/MM simulations within the context of energy and free energy calculations using a proton transfer in a DNA base pair as a test case. In the simulations, the QM region was treated with a dispersion-corrected AM1/d-PhoT Hamiltonian, which was developed to accurately describe phosphoryl and proton transfer reactions, in conjunction with an electrostatic embedding scheme using the particle-mesh Ewald summation method. With this rigorous QM/MM potential, we performed rather extensive QM/MM sampling, and found that the free energy reaction profiles converge rapidly with respect to the QM region size within ca. ±1 kcal/mol. This finding suggests that the strategy of QM/MM simulations with reasonably sized and selected QM regions, which has been employed for over four decades, is a valid approach for modeling complex biomolecular systems. We point to possible causes for the sensitivity of the energy and free energy calculations to the size of the QM region, and potential implications.

  11. Is Parental Involvement Lower at Larger Schools?

    Science.gov (United States)

    Walsh, Patrick

    2010-01-01

    Parents who volunteer, or who lobby for improvements in school quality, are generally seen as providing a school-wide public good. If so, straightforward public-good theory predicts that free-riding will reduce average involvement at larger schools. This study uses longitudinal data to follow families over time, as their children move from middle…

  12. Stepwise transformation of the molecular building blocks in a porphyrin-encapsulating metal-organic material

    KAUST Repository

    Zhang, ZhenJie

    2013-04-24

    When immersed in solutions containing Cu(II) cations, the microporous metal-organic material P11 ([Cd4(BPT)4]·[Cd(C 44H36N8)(S)]·[S], BPT = biphenyl-3,4′,5-tricarboxylate) undergoes a transformation of its [Cd 2(COO)6]2- molecular building blocks (MBBs) into novel tetranuclear [Cu4X2(COO)6(S) 2] MBBs to form P11-Cu. The transformation occurs in single-crystal to single-crystal fashion, and its stepwise mechanism was studied by varying the Cd2+/Cu2+ ratio of the solution in which crystals of P11 were immersed. P11-16/1 (Cd in framework retained, Cd in encapsulated porphyrins exchanged) and other intermediate phases were thereby isolated and structurally characterized. P11-16/1 and P11-Cu retain the microporosity of P11, and the relatively larger MBBs in P11-Cu permit a 20% unit cell expansion and afford a higher surface area and a larger pore size. © 2013 American Chemical Society.

  13. Electronic transport properties of phenylacetylene molecular junctions

    International Nuclear Information System (INIS)

    Liu Wen; Cheng Jie; Yan Cui-Xia; Li Hai-Hong; Wang Yong-Juan; Liu De-Sheng

    2011-01-01

    Electronic transport properties of a kind of phenylacetylene compound— (4-mercaptophenyl)-phenylacetylene are calculated by the first-principles method in the framework of density functional theory and the nonequilibrium Green's function formalism. The molecular junction shows an obvious rectifying behaviour at a bias voltage larger than 1.0 V. The rectification effect is attributed to the asymmetry of the interface contacts. Moreover, at a bias voltage larger than 2.0 V, which is not referred to in a relevant experiment [Fang L, Park J Y, Ma H, Jen A K Y and Salmeron M 2007 Langmuir 23 11522], we find a negative differential resistance phenomenon. The negative differential resistance effect may originate from the change of the delocalization degree of the molecular orbitals induced by the bias. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  14. Enhancing Irreversible Electroporation by Manipulating Cellular Biophysics with a Molecular Adjuvant.

    Science.gov (United States)

    Ivey, Jill W; Latouche, Eduardo L; Richards, Megan L; Lesser, Glenn J; Debinski, Waldemar; Davalos, Rafael V; Verbridge, Scott S

    2017-07-25

    Pulsed electric fields applied to cells have been used as an invaluable research tool to enhance delivery of genes or other intracellular cargo, as well as for tumor treatment via electrochemotherapy or tissue ablation. These processes involve the buildup of charge across the cell membrane, with subsequent alteration of transmembrane potential that is a function of cell biophysics and geometry. For traditional electroporation parameters, larger cells experience a greater degree of membrane potential alteration. However, we have recently demonstrated that the nuclear/cytoplasm ratio (NCR), rather than cell size, is a key predictor of response for cells treated with high-frequency irreversible electroporation (IRE). In this study, we leverage a targeted molecular therapy, ephrinA1, known to markedly collapse the cytoplasm of cells expressing the EphA2 receptor, to investigate how biophysical cellular changes resulting from NCR manipulation affect the response to IRE at varying frequencies. We present evidence that the increase in the NCR mitigates the cell death response to conventional electroporation pulsed-electric fields (∼100 μs), consistent with the previously noted size dependence. However, this same molecular treatment enhanced the cell death response to high-frequency electric fields (∼1 μs). This finding demonstrates the importance of considering cellular biophysics and frequency-dependent effects in developing electroporation protocols, and our approach provides, to our knowledge, a novel and direct experimental methodology to quantify the relationship between cell morphology, pulse frequency, and electroporation response. Finally, this novel, to our knowledge, combinatorial approach may provide a paradigm to enhance in vivo tumor ablation through a molecular manipulation of cellular morphology before IRE application. Copyright © 2017 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  15. More Than Filaments and Cores: Statistical Study of Structure Formation and Dynamics in Nearby Molecular Clouds

    Science.gov (United States)

    Chen, How-Huan; Goodman, Alyssa

    2018-01-01

    In the past decade, multiple attempts at understanding the connection between filaments and star forming cores have been made using observations across the entire epectrum. However, the filaments and the cores are usually treated as predefined--and well-defined--entities, instead of structures that often come at different sizes, shapes, with substantially different dynamics, and inter-connected at different scales. In my dissertation, I present an array of studies using different statistical methods, including the dendrogram and the probability distribution function (PDF), of structures at different size scales within nearby molecular clouds. These structures are identified using observations of different density tracers, and where possible, in the multi-dimensional parameter space of key dynamic properties--the LSR velocity, the velocity dispersion, and the column density. The goal is to give an overview of structure formation in nearby star-forming clouds, as well as of the dynamics in these structures. I find that the overall statistical properties of a larger structure is often the summation/superposition of sub-structures within, and that there could be significant variations due to local physical processes. I also find that the star formation process within molecular clouds could in fact take place in a non-monolithic manner, connecting potentially merging and/or transient structures, at different scales.

  16. Microwave radiation hydrothermal synthesis and characterization of micro- and mesoporous composite molecular sieve Y/SBA-15

    Directory of Open Access Journals (Sweden)

    Wenyuan Wu

    2017-05-01

    Full Text Available A microwave radiation hydrothermal method to control synthesis of micro- and mesoporous Y/SBA-15 composite molecular sieves was reported. The synthesized SBA-15 and Y/SBA-15 were characterized by scanning electron microscopy (SEM and N2 adsorption–desorption. The three kinds of different concentrations of hydrochloric acid (0.75 M, 2 M and 3.25 M were used to investigate the effect on Y/SBA-15. The analysis results of the composite products indicated that the optimization synthesis condition employed zeolite type Y and TEOS as silicon sources under 0.75 M hydrochloric acid by the microwave radiation hydrothermal synthesis method. The N2 adsorption–desorption test results of micro–mesoporous composite molecular sieve type Y/SBA-15 in mesoporous extent indicated that SBET is 355.529 m2/g, D‾BET is 4.050 nm, and mesoporous aperture focuses on the distribution region of 5.3 nm. It was found that the received composite product has an appropriate proportion of smaller size, larger size pore structure and the thicker pore wall. In addition, its internal channels have a high degree of order and smooth flow in long-range channels.

  17. Mother-Offspring Relations: Prey Quality and Maternal Size Affect Egg Size of an Acariphagous Lady Beetle in Culture

    Directory of Open Access Journals (Sweden)

    Eric W. Riddick

    2012-01-01

    Full Text Available We investigated mother-offspring relations in a lady beetle Stethorus punctillum Weise that utilizes spider mites as prey. Our objectives were to determine if (1 prey quality affects egg size, (2 maternal size correlates with egg size, and (3 egg size affects hatching success. We fed predators spider mites Tetranychus urticae Koch from lima bean Phaseolus lunatus L. foliage in the laboratory. Mothers of unknown body size offered high rather than low quality spider mites since birth produced larger eggs. Mothers of known body size offered only high quality spider mites, produced eggs of variable size, but mean egg size correlated positively with hind femur length. Mothers laid their eggs singly, rather than in batches, and eggs were large relative to femur size. Egg size did not affect hatch success; mean hatch rate exceeded 95% regardless of egg size. In conclusion, the quality of prey consumed by S. punctillum mothers while in the larval stage can affect their size as adults and, consequently, the size of their eggs. The behavior of laying eggs singly, the positive relationship between maternal size and mean egg size, and the high rate of egg hatch suggest that S. punctillum mothers invest heavily in offspring.

  18. From the point-of-purchase perspective: a qualitative study of the feasibility of interventions aimed at portion-size.

    Science.gov (United States)

    Vermeer, Willemijn M; Steenhuis, Ingrid H M; Seidell, Jacob C

    2009-04-01

    Food portion-sizes might be a promising starting point for interventions targeting obesity. The purpose of this qualitative study was to assess how representatives of point-of-purchase settings perceived the feasibility of interventions aimed at portion-size. Semi-structured interviews were conducted with 22 representatives of various point-of-purchase settings. Constructs derived from the diffusion of innovations theory were incorporated into the interview guide. Each interview was recorded and transcribed verbatim. Data were coded and analysed with Atlas.ti 5.2 using the framework approach. According to the participants, offering a larger variety of portion-sizes had the most relative advantages, and reducing portions was the most disadvantageous. The participants also considered portion-size reduction and linear pricing of portion-sizes to be risky. Lastly, a larger variety of portion-sizes, pricing strategies and portion-size labelling were seen as the most complex interventions. In general, participants considered offering a larger variety of portion-sizes, portion-size labelling and, to a lesser extent, pricing strategies with respect to portion-sizes as most feasible to implement. Interventions aimed at portion-size were seen as innovative by most participants. Developing adequate communication strategies about portion-size interventions with both decision-makers in point-of-purchase settings and the general public is crucial for successful implementation.

  19. Molecular dynamics simulations of the effect of shape and size of SiO2 nanoparticle dopants on insulation paper cellulose

    Directory of Open Access Journals (Sweden)

    Chao Tang

    2016-12-01

    Full Text Available The effect of silica nanoparticle (Nano-SiO2 dopants on insulation paper cellulose, and the interaction between them, was investigated using molecular dynamics simulations. The mechanical properties, interactions, and cellulose-Nano-SiO2 compatibility of composite models of cellulose doped with Nano-SiO2 were studied. An increase in Nano-SiO2 size leads to a decrease in the mechanical properties, and a decrease in the anti-deformation ability of the composite model. The binding energies and bond energies per surface area of the composite models indicate that the bonding interaction between spherical Nano-SiO2 and cellulose is the strongest among the four different Nano-SiO2 shapes that are investigated. The solubilities of the four composite models decrease with increasing Nano-SiO2 size, and the difference between the solubility of pure cellulose and those of the composite models increases with increasing Nano-SiO2 size. Good doping effects with the highest cellulose-Nano-SiO2 compatibility are achieved for the cellulose model doped with spherical Nano-SiO2 of 10 Å in diameter. These findings provide a method for modifying the mechanical properties of cellulose by doping, perhaps for improving insulation dielectrics.

  20. Decreases in beetle body size linked to climate change and warming temperatures.

    Science.gov (United States)

    Tseng, Michelle; Kaur, Katrina M; Soleimani Pari, Sina; Sarai, Karnjit; Chan, Denessa; Yao, Christine H; Porto, Paula; Toor, Anmol; Toor, Harpawantaj S; Fograscher, Katrina

    2018-05-01

    Body size is a fundamental ecological trait and is correlated with population dynamics, community structure and function, and ecosystem fluxes. Laboratory data from broad taxonomic groups suggest that a widespread response to a warming world may be an overall decrease in organism body size. However, given the myriad of biotic and abiotic factors that can also influence organism body size in the wild, it is unclear whether results from these laboratory assays hold in nature. Here we use datasets spanning 30 to 100 years to examine whether the body size of wild-caught beetles has changed over time, whether body size changes are correlated with increased temperatures, and we frame these results using predictions derived from a quantitative review of laboratory responses of 22 beetle species to temperature. We found that 95% of laboratory-reared beetles decreased in size with increased rearing temperature, with larger-bodied species shrinking disproportionately more than smaller-bodied beetles. In addition, the museum datasets revealed that larger-bodied beetle species have decreased in size over time, that mean beetle body size explains much of the interspecific variation in beetle responses to temperature, and that long-term beetle size changes are explained by increases in autumn temperature and decreases in spring temperature in this region. Our data demonstrate that the relationship between body size and temperature of wild-caught beetles matches relatively well with results from laboratory studies, and that variation in this relationship is largely explained by interspecific variation in mean beetle body size. This long-term beetle dataset is one of the most comprehensive arthropod body size datasets compiled to date, it improves predictions regarding the shrinking of organisms with global climate change, and together with the meta-analysis data, call for new hypotheses to explain why larger-bodied organisms may be more sensitive to temperature. © 2018 The

  1. Molecular dynamics simulation of potentiometric sensor response: the effect of biomolecules, surface morphology and surface charge.

    Science.gov (United States)

    Lowe, B M; Skylaris, C-K; Green, N G; Shibuta, Y; Sakata, T

    2018-05-10

    The silica-water interface is critical to many modern technologies in chemical engineering and biosensing. One technology used commonly in biosensors, the potentiometric sensor, operates by measuring the changes in electric potential due to changes in the interfacial electric field. Predictive modelling of this response caused by surface binding of biomolecules remains highly challenging. In this work, through the most extensive molecular dynamics simulation of the silica-water interfacial potential and electric field to date, we report a novel prediction and explanation of the effects of nano-morphology on sensor response. Amorphous silica demonstrated a larger potentiometric response than an equivalent crystalline silica model due to increased sodium adsorption, in agreement with experiments showing improved sensor response with nano-texturing. We provide proof-of-concept that molecular dynamics can be used as a complementary tool for potentiometric biosensor response prediction. Effects that are conventionally neglected, such as surface morphology, water polarisation, biomolecule dynamics and finite-size effects, are explicitly modelled.

  2. Genome size variation in the genus Avena.

    Science.gov (United States)

    Yan, Honghai; Martin, Sara L; Bekele, Wubishet A; Latta, Robert G; Diederichsen, Axel; Peng, Yuanying; Tinker, Nicholas A

    2016-03-01

    Genome size is an indicator of evolutionary distance and a metric for genome characterization. Here, we report accurate estimates of genome size in 99 accessions from 26 species of Avena. We demonstrate that the average genome size of C genome diploid species (2C = 10.26 pg) is 15% larger than that of A genome species (2C = 8.95 pg), and that this difference likely accounts for a progression of size among tetraploid species, where AB genome configuration had similar genome sizes (average 2C = 25.74 pg). Genome size was mostly consistent within species and in general agreement with current information about evolutionary distance among species. Results also suggest that most of the polyploid species in Avena have experienced genome downsizing in relation to their diploid progenitors. Genome size measurements could provide additional quality control for species identification in germplasm collections, especially in cases where diploid and polyploid species have similar morphology.

  3. A simple shear limited, single size, time dependent flocculation model

    Science.gov (United States)

    Kuprenas, R.; Tran, D. A.; Strom, K.

    2017-12-01

    This research focuses on the modeling of flocculation of cohesive sediment due to turbulent shear, specifically, investigating the dependency of flocculation on the concentration of cohesive sediment. Flocculation is important in larger sediment transport models as cohesive particles can create aggregates which are orders of magnitude larger than their unflocculated state. As the settling velocity of each particle is determined by the sediment size, density, and shape, accounting for this aggregation is important in determining where the sediment is deposited. This study provides a new formulation for flocculation of cohesive sediment by modifying the Winterwerp (1998) flocculation model (W98) so that it limits floc size to that of the Kolmogorov micro length scale. The W98 model is a simple approach that calculates the average floc size as a function of time. Because of its simplicity, the W98 model is ideal for implementing into larger sediment transport models; however, the model tends to over predict the dependency of the floc size on concentration. It was found that the modification of the coefficients within the original model did not allow for the model to capture the dependency on concentration. Therefore, a new term within the breakup kernel of the W98 formulation was added. The new formulation results is a single size, shear limited, and time dependent flocculation model that is able to effectively capture the dependency of the equilibrium size of flocs on both suspended sediment concentration and the time to equilibrium. The overall behavior of the new model is explored and showed align well with other studies on flocculation. Winterwerp, J. C. (1998). A simple model for turbulence induced flocculation of cohesive sediment. .Journal of Hydraulic Research, 36(3):309-326.

  4. Finite Size Scaling of Perceptron

    OpenAIRE

    Korutcheva, Elka; Tonchev, N.

    2000-01-01

    We study the first-order transition in the model of a simple perceptron with continuous weights and large, bit finite value of the inputs. Making the analogy with the usual finite-size physical systems, we calculate the shift and the rounding exponents near the transition point. In the case of a general perceptron with larger variety of inputs, the analysis only gives bounds for the exponents.

  5. Effect of particle size on thermal decomposition of alkali metal picrates

    International Nuclear Information System (INIS)

    Liu, Rui; Zhang, Tonglai; Yang, Li; Zhou, Zunning

    2014-01-01

    Graphical abstract: The smaller-sized picrate has greater gas emission than do its larger counterpart. The small size effect reduces the thermal decomposition activation energy, accelerates the reaction rate, and promotes the reaction activity. - Highlights: • Picrates were prepared into three micron sizes by microemulsion synthesis. • Thermal decomposition kinetics and thermodynamics were studied by DPTA and DSC. • Smaller-sized picrate has higher activity and faster reaction rate. • Particle size effect on thermal decomposition kinetics and thermodynamics was revealed. - Abstract: Three alkali metal picrates, KPA, RbPA and CsPA, were prepared into three micron sizes by microemulsion synthesis, and their thermal decomposition behaviors were investigated by DPTA at different temperatures and by DSC at different heating rates. The smaller-sized picrate has greater gas emission and smaller kinetic and thermodynamic parameters than do its larger counterpart. It can be attributed to the decreasing particle size which leads to the high surface energy, the fast mass and heat transfer, and the increasing active sites on the reaction interface. The small size effect and surface effect cause the autocatalysis which reduces the activation energy and promotes the reaction activity. The particle size does not affect the reaction mechanism. However, the picrates with different central alkali metals exhibit different reaction mechanisms even though they are of the same size. This is because the central metal determines the bond energy and consequently affects the stability of picrate

  6. Effect of particle size on thermal decomposition of alkali metal picrates

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Rui; Zhang, Tonglai, E-mail: ztlbit@bit.edu.cn; Yang, Li; Zhou, Zunning

    2014-05-01

    Graphical abstract: The smaller-sized picrate has greater gas emission than do its larger counterpart. The small size effect reduces the thermal decomposition activation energy, accelerates the reaction rate, and promotes the reaction activity. - Highlights: • Picrates were prepared into three micron sizes by microemulsion synthesis. • Thermal decomposition kinetics and thermodynamics were studied by DPTA and DSC. • Smaller-sized picrate has higher activity and faster reaction rate. • Particle size effect on thermal decomposition kinetics and thermodynamics was revealed. - Abstract: Three alkali metal picrates, KPA, RbPA and CsPA, were prepared into three micron sizes by microemulsion synthesis, and their thermal decomposition behaviors were investigated by DPTA at different temperatures and by DSC at different heating rates. The smaller-sized picrate has greater gas emission and smaller kinetic and thermodynamic parameters than do its larger counterpart. It can be attributed to the decreasing particle size which leads to the high surface energy, the fast mass and heat transfer, and the increasing active sites on the reaction interface. The small size effect and surface effect cause the autocatalysis which reduces the activation energy and promotes the reaction activity. The particle size does not affect the reaction mechanism. However, the picrates with different central alkali metals exhibit different reaction mechanisms even though they are of the same size. This is because the central metal determines the bond energy and consequently affects the stability of picrate.

  7. New aids for the non-invasive prenatal diagnosis of achondroplasia: dysmorphic features, charts of fetal size and molecular confirmation using cell-free fetal DNA in maternal plasma.

    Science.gov (United States)

    Chitty, L S; Griffin, D R; Meaney, C; Barrett, A; Khalil, A; Pajkrt, E; Cole, T J

    2011-03-01

    To improve the prenatal diagnosis of achondroplasia by constructing charts of fetal size, defining frequency of sonographic features and exploring the role of non-invasive molecular diagnosis based on cell-free fetal deoxyribonucleic acid (DNA) in maternal plasma. Data on fetuses with a confirmed diagnosis of achondroplasia were obtained from our databases, records reviewed, sonographic features and measurements determined and charts of fetal size constructed using the LMS (lambda-mu-sigma) method and compared with charts used in normal pregnancies. Cases referred to our regional genetics laboratory for molecular diagnosis using cell-free fetal DNA were identified and results reviewed. Twenty-six cases were scanned in our unit. Fetal size charts showed that femur length was usually on or below the 3(rd) centile by 25 weeks' gestation, and always below the 3(rd) by 30 weeks. Head circumference was above the 50(th) centile, increasing to above the 95(th) when compared with normal for the majority of fetuses. The abdominal circumference was also increased but to a lesser extent. Commonly reported sonographic features were bowing of the femora, frontal bossing, short fingers, a small chest and polyhydramnios. Analysis of cell-free fetal DNA in six pregnancies confirmed the presence of the c.1138G > A mutation in the FGRF3 gene in four cases with achondroplasia, but not the two subsequently found to be growth restricted. These data should improve the accuracy of diagnosis of achondroplasia based on sonographic findings, and have implications for targeted molecular confirmation that can reliably and safely be carried out using cell-free fetal DNA. Copyright © 2011 ISUOG. Published by John Wiley & Sons, Ltd.

  8. Molecular scale

    Directory of Open Access Journals (Sweden)

    Christopher H. Childers

    2016-03-01

    Full Text Available This manuscript demonstrates the molecular scale cure rate dependence of di-functional epoxide based thermoset polymers cured with amines. A series of cure heating ramp rates were used to determine the influence of ramp rate on the glass transition temperature (Tg and sub-Tg transitions and the average free volume hole size in these systems. The networks were comprised of 3,3′-diaminodiphenyl sulfone (33DDS and diglycidyl ether of bisphenol F (DGEBF and were cured at ramp rates ranging from 0.5 to 20 °C/min. Differential scanning calorimetry (DSC and NIR spectroscopy were used to explore the cure ramp rate dependence of the polymer network growth, whereas broadband dielectric spectroscopy (BDS and free volume hole size measurements were used to interrogate networks’ molecular level structural variations upon curing at variable heating ramp rates. It was found that although the Tg of the polymer matrices was similar, the NIR and DSC measurements revealed a strong correlation for how these networks grow in relation to the cure heating ramp rate. The free volume analysis and BDS results for the cured samples suggest differences in the molecular architecture of the matrix polymers due to cure heating rate dependence.

  9. Sample-size dependence of diversity indices and the determination of sufficient sample size in a high-diversity deep-sea environment

    OpenAIRE

    Soetaert, K.; Heip, C.H.R.

    1990-01-01

    Diversity indices, although designed for comparative purposes, often cannot be used as such, due to their sample-size dependence. It is argued here that this dependence is more pronounced in high diversity than in low diversity assemblages and that indices more sensitive to rarer species require larger sample sizes to estimate diversity with reasonable precision than indices which put more weight on commoner species. This was tested for Hill's diversity number N sub(0) to N sub( proportional ...

  10. Prey size selection and cannibalistic behaviour of juvenile barramundi Lates calcarifer.

    Science.gov (United States)

    Ribeiro, F F; Qin, J G

    2015-05-01

    This study assessed the cannibalistic behaviour of juvenile barramundi Lates calcarifer and examined the relationship between prey size selection and energy gain of cannibals. Prey handling time and capture success by cannibals were used to estimate the ratio of energy gain to energy cost in prey selection. Cannibals selected smaller prey despite its capability of ingesting larger prey individuals. In behavioural analysis, prey handling time significantly increased with prey size, but it was not significantly affected by cannibal size. Conversely, capture success significantly decreased with the increase of both prey and cannibal sizes. The profitability indices showed that the smaller prey provides the most energy return for cannibals of all size classes. These results indicate that L. calcarifer cannibals select smaller prey for more profitable return. The behavioural analysis, however, indicates that L. calcarifer cannibals attack prey of all size at a similar rate but ingest smaller prey more often, suggesting that prey size selection is passively orientated rather than at the predator's choice. The increase of prey escape ability and morphological constraint contribute to the reduction of intracohort cannibalism as fish grow larger. This study contributes to the understanding of intracohort cannibalism and development of strategies to reduce fish cannibalistic mortalities. © 2015 The Fisheries Society of the British Isles.

  11. Family Medicine Panel Size with Care Teams: Impact on Quality.

    Science.gov (United States)

    Angstman, Kurt B; Horn, Jennifer L; Bernard, Matthew E; Kresin, Molly M; Klavetter, Eric W; Maxson, Julie; Willis, Floyd B; Grover, Michael L; Bryan, Michael J; Thacher, Tom D

    2016-01-01

    The demand for comprehensive primary health care continues to expand. The development of team-based practice allows for improved capacity within a collective, collaborative environment. Our hypothesis was to determine the relationship between panel size and access, quality, patient satisfaction, and cost in a large family medicine group practice using a team-based care model. Data were retrospectively collected from 36 family physicians and included total panel size of patients, percentage of time spent on patient care, cost of care, access metrics, diabetic quality metrics, patient satisfaction surveys, and patient care complexity scores. We used linear regression analysis to assess the relationship between adjusted physician panel size, panel complexity, and outcomes. The third available appointments (P size. Patient satisfaction, cost, and percentage fill rate were not affected by panel size. A physician-adjusted panel size larger than the current mean (2959 patients) was associated with a greater likelihood of poor-quality rankings (≤25th percentile) compared with those with a less than average panel size (odds ratio [OR], 7.61; 95% confidence interval [CI], 1.13-51.46). Increased panel size was associated with a longer time to the third available appointment (OR, 10.9; 95% CI, 1.36-87.26) compared with physicians with panel sizes smaller than the mean. We demonstrated a negative impact of larger panel size on diabetic quality results and available appointment access. Evaluation of a family medicine practice parameters while controlling for panel size and patient complexity may help determine the optimal panel size for a practice. © Copyright 2016 by the American Board of Family Medicine.

  12. Immediate radical trachelectomy versus neoadjuvant chemotherapy followed by conservative surgery for patients with stage IB1 cervical cancer with tumors 2cm or larger: A literature review and analysis of oncological and obstetrical outcomes.

    Science.gov (United States)

    Pareja, Rene; Rendón, Gabriel J; Vasquez, Monica; Echeverri, Lina; Sanz-Lomana, Carlos Millán; Ramirez, Pedro T

    2015-06-01

    Radical trachelectomy is the treatment of choice in women with early-stage cervical cancer wishing to preserve fertility. Radical trachelectomy can be performed with a vaginal, abdominal, or laparoscopic/robotic approach. Vaginal radical trachelectomy (VRT) is generally not offered to patients with tumors 2cm or larger because of a high recurrence rate. There are no conclusive recommendations regarding the safety of abdominal radical trachelectomy (ART) or laparoscopic radical trachelectomy (LRT) in such patients. Several investigators have used neoadjuvant chemotherapy in patients with tumors 2 to 4cm to reduce tumor size so that fertility preservation may be offered. However, to our knowledge, no published study has compared outcomes between patients with cervical tumors 2cm or larger who underwent immediate radical trachelectomy and those who underwent neoadjuvant chemotherapy followed by radical trachelectomy. We conducted a literature review to compare outcomes with these 2 approaches. Our main endpoints for evaluation were oncological and obstetrical outcomes. The fertility preservation rate was 82.7%, 85.1%, 89%; and 91.1% for ART (tumors larger than >2cm), ART (all sizes), NACT followed by surgery and VRT (all sizes); respectively. The global pregnancy rate was 16.2%, 24% and 30.7% for ART, VRT, and NACT followed by surgery; respectively. The recurrence rate was 3.8%, 4.2%, 6%, 7.6% and 17% for ART (all sizes), VRT (all sizes), ART (tumors>2cm), NACT followed by surgery, and VRT (tumors>2cm). These outcomes must be considered when offering a fertility sparing technique to patients with a tumor larger than 2cm. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Fucosylated chondroitin sulfate oligosaccharides exert anticoagulant activity by targeting at intrinsic tenase complex with low FXII activation: Importance of sulfation pattern and molecular size.

    Science.gov (United States)

    Li, Junhui; Li, Shan; Yan, Lufeng; Ding, Tian; Linhardt, Robert J; Yu, Yanlei; Liu, Xinyue; Liu, Donghong; Ye, Xingqian; Chen, Shiguo

    2017-10-20

    Fucosylated chondroitin sulfates (fCSs) are structurally unusual glycosaminoglycans isolated from sea cucumbers that exhibit potent anticoagulant activity. These fCSs were isolated from sea cucumber, Isostichopus badionotus and Pearsonothuria graeffei. Fenton reaction followed by gel filtration chromatography afforded fCS oligosaccharides, with different sulfation patterns identified by mass and NMR spectroscopy, and these were used to clarify the relationship between the structures and the anticoagulant activities of fCSs. In vitro activities were measured by activated partial thromboplastin time (APTT), thrombin time (TT), thrombin and factor Xa inhibition, and activation of FXII. The results showed that free radicals preferentially acted on GlcA residues affording oligosaccharides that were purified from both fCSs. The inhibition of thrombin and factor X activities, mediated through antithrombin III and heparin cofactor II of fCSs oligosaccharides were affected by their molecular weight and fucose branches. Oligosaccharides with different sulfation patterns of the fucose branching had a similar ability to inhibit the FXa by the intrinsic factor Xase (factor IXa-VIIIa complex). Oligosaccharides with 2,4-O-sulfo fucose branches from fCS-Ib showed higher activities than ones with 3,4-O-disulfo branches obtained from fCS-Pg. Furthermore, a heptasaccharide is the minimum size oligosaccharide required for anticoagulation and FXII activation. This activity was absent for fCS oligosaccharides smaller than nonasaccharides. Molecular size and fucose branch sulfation are important for anticoagulant activity and reduction of size can reverse the activation of FXII caused by native fCSs. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  14. Dynamical stability of the one-dimensional rigid Brownian rotator: the role of the rotator’s spatial size and shape

    Science.gov (United States)

    Jeknić-Dugić, Jasmina; Petrović, Igor; Arsenijević, Momir; Dugić, Miroljub

    2018-05-01

    We investigate dynamical stability of a single propeller-like shaped molecular cogwheel modelled as the fixed-axis rigid rotator. In the realistic situations, rotation of the finite-size cogwheel is subject to the environmentally-induced Brownian-motion effect that we describe by utilizing the quantum Caldeira-Leggett master equation. Assuming the initially narrow (classical-like) standard deviations for the angle and the angular momentum of the rotator, we investigate the dynamics of the first and second moments depending on the size, i.e. on the number of blades of both the free rotator as well as of the rotator in the external harmonic field. The larger the standard deviations, the less stable (i.e. less predictable) rotation. We detect the absence of the simple and straightforward rules for utilizing the rotator’s stability. Instead, a number of the size-related criteria appear whose combinations may provide the optimal rules for the rotator dynamical stability and possibly control. In the realistic situations, the quantum-mechanical corrections, albeit individually small, may effectively prove non-negligible, and also revealing subtlety of the transition from the quantum to the classical dynamics of the rotator. As to the latter, we detect a strong size-dependence of the transition to the classical dynamics beyond the quantum decoherence process.

  15. Relationship between self-discrepancy and worries about penis size in men with body dysmorphic disorder.

    Science.gov (United States)

    Veale, David; Miles, Sarah; Read, Julie; Bramley, Sally; Troglia, Andrea; Carmona, Lina; Fiorito, Chiara; Wells, Hannah; Wylie, Kevan; Muir, Gordon

    2016-06-01

    We explored self-discrepancy in men with body dysmorphic disorder (BDD) concerned about penis size, men without BDD but anxious about penis size, and controls. Men with BDD (n=26) were compared to those with small penis anxiety (SPA; n=31) and controls (n=33), objectively (by measuring) and investigating self-discrepancy: actual size, ideal size, and size they felt they should be according to self and other. Most men under-estimated their penis size, with the BDD group showing the greatest discrepancy between perceived and ideal size. The SPA group showed a larger discrepancy than controls. This was replicated for the perceptions of others, suggesting the BDD group internalised the belief that they should have a larger penis size. There was a significant correlation between symptoms of BDD and this discrepancy. This self-actual and self-ideal/self-should discrepancy and the role of comparing could be targeted in therapy. Copyright © 2016. Published by Elsevier Ltd.

  16. Sizing solar home systems for optimal development impact

    International Nuclear Information System (INIS)

    Bond, M.; Fuller, R.J.; Aye, Lu

    2012-01-01

    The paper compares the development impact of three different sized solar home systems (SHS) (10, 40 and 80 W p ) installed in rural East Timor. It describes research aimed to determine whether the higher cost of the larger systems was justified by additional household benefits. To assess the development impact of these different sizes of SHS the research used a combination of participatory and quantitative tools. Participatory exercises were conducted with seventy-seven small groups of SHS users in twenty-four rural communities and supplemented with a household survey of 195 SHS users. The combined results of these evaluation processes enabled the three sizes of SHS to be compared for two types of benefits—those associated with carrying out important household tasks and attributes of SHS which were advantageous compared to the use of non-electric lighting sources. The research findings showed that the small, 10 W p SHS provided much of the development impact of the larger systems. It suggests three significant implications for the design of SHS programs in contexts such as East Timor: provide more small systems rather than fewer large ones; provide lighting in the kitchen wherever possible; and carefully match SHS operating costs to the incomes of rural users. - Highlights: ► We compare development benefits for 3 sizes of solar home systems—10, 40 and 80 W p . ► Benefit assessment uses a combination of qualitative and quantitative approaches. ► Small systems are found to provide much of the benefits of the larger systems. ► To maximise benefits systems should be fitted with luminaires in kitchen areas. ► Financial benefits are important to users and may not accrue for large systems.

  17. Measuring the size of an earthquake

    Science.gov (United States)

    Spence, W.; Sipkin, S.A.; Choy, G.L.

    1989-01-01

    Earthquakes range broadly in size. A rock-burst in an Idaho silver mine may involve the fracture of 1 meter of rock; the 1965 Rat Island earthquake in the Aleutian arc involved a 650-kilometer length of the Earth's crust. Earthquakes can be even smaller and even larger. If an earthquake is felt or causes perceptible surface damage, then its intensity of shaking can be subjectively estimated. But many large earthquakes occur in oceanic areas or at great focal depths and are either simply not felt or their felt pattern does not really indicate their true size.

  18. Comb polymer architecture and particle size effects on the behavior of biphasic nanoparticle inks for direct-write assembly

    Science.gov (United States)

    Yoshikawa, Jun

    Biphasic nanoparticle mixtures composed of attractive and repulsive colloidal species enable the direct-write assembly of 3D structures with much finer features than those produced by pure colloidal gels. These mixtures rely on the use of comb polymer dispersants to render one particle population stable, while the other population is attractive. In this thesis, we systematically investigate the effects of comb polymer architecture and particle size ratio on the behavior of biphasic nanoparticle inks with the overarching aim of further advancing the direct-write assembly of 3D colloidal structures. We first investigated the effects of both pure polyelectrolytes, poly(acrylic acid) (PAA) and poly(methacrylic acid) (PMAA), and comb polymer dispersants composed of a PMAA backbone with methoxy-poly(ethylene oxide) (mPEO) teeth of varying molecular weights on the stability of barium titanate (BaTiO 3) suspensions. While each dispersant imparts stability to BaTiO 3 nanoparticles at low ionic strength (teeth (MWteeth = 2000) provides stability at higher ionic strengths over a broad range of particle sizes and counterion valencies. These results provide guidelines for tailoring the molecular architecture and functionality of comb polymer dispersants for optimal stabilization of the repulsive particle population within the biphasic inks. Next, particle size effects on the rheological properties of biphasic nanoparticle suspensions are studied. Shear elastic modulus, shear yield stress, and compressive yield stress are measured for mixtures of varying total volume fraction, attractive-to-repulsive volume fraction, and particle size ratio between attractive and repulsive species. Our observations indicate that the repulsive particles hinder the formation of the attractive gel network. The time required for shear elastic modulus to approach a steady-state value increases with the fraction of repulsive species. Furthermore, this behavior becomes more significant with increasing

  19. Sustainability and Small to Medium Sized Enterprises--How to Engage Them

    Science.gov (United States)

    Condon, Linda

    2004-01-01

    Small and medium sized enterprises (SMEs) have a major advantage over larger organisations in regard to addressing sustainability issues--their size means they are able to react very quickly to changes in the business environment. They are disadvantaged, however, by lack of information on marketplace changes that make sustainability an opportunity…

  20. Atomic size effect on the formation of ionized cluster beam epitaxy in Lennard-Jones systems

    International Nuclear Information System (INIS)

    Hsieh Horngming; Averback, R.S.

    1991-01-01

    Ionized cluster beam deposition is studied by molecular dynamics simulations in which the atomic size of incident cluster atoms is different from the size of substrate atoms. Lennard-Jones interatomic potentials are used for the two-component system. The results provide the morphologies of the overlayers for various atomic sizes and are compared to simulation results of molecular beam epitaxy. (orig.)

  1. The Effects of Particle Size on the Surface Properties of an HVOF Coating of WC-Co

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Tong Yul; Yoon, Jae Hong; Yoon, Sang Hwan; Joo, Yun Kon [Changwon National University, Changwon (Korea, Republic of); Choi, Won Ho; Son, Young Bok [Xinix Metallizing Co., Ltd, Gyungnam (Korea, Republic of)

    2017-04-15

    The effects of particle size on the surface properties of HVOF spray coating were studied to improve of the durability of metal components. Micro and nano sized WC-12Co powders were coated on the surface of Inconel718, and the effects of particle size on surface properties were studied. Surface hardness was reduced when the particle sizes of the powder were decreased, because the larger specific surface area of the smaller particles caused greater heat absorption and decomposition of the hard WC to less hard W{sub 2}C and graphite. Porosity was increased by decreasing the particle size, because the larger specific surface area of the smaller particles caused a greater decomposition of WC to W{sub 2}C and free carbon. The free carbon formed carbon oxide gases which created the porous surface. The friction coefficient was reduced by decreasing the particle size because the larger specific surface area of the smaller particles produced more free carbon free Co and Co oxide which acted as solid lubricants. The friction coefficient increased when the surface temperature was increased from 25 to 500 ℃, due to local cold welding. To improve the durability of metal mechanical components, WC-Co coating with the proper particle size is recommended.

  2. An assessment of glass microspheres for use as number-based aerodynamic size standards

    International Nuclear Information System (INIS)

    Ball, M.H.E.; Marshall, I.A.; Mitchell, J.P.; Rideal, G.

    1989-08-01

    Polydisperse, non-porous microspheres are required with well-defined aerodynamic properties to determine if enhanced settling of micron-sized aerosol particles occurs in the presence of larger particles (gravitational agglomeration). Glass spheres with claimed unimodal narrow distributions were evaluated using a TSI Aerodynamic Particle Sizer (APS33B). The size fractions containing particles in the range from 1 to 5 μm aerodynamic diameter were truly unimodal, but the fractions which were supposed to consist solely of particles larger than 5 μm aerodynamic diameter contained a significant proportion of submicron particles. (author)

  3. Quantifying the effect of colony size and food distribution on harvester ant foraging.

    Directory of Open Access Journals (Sweden)

    Tatiana P Flanagan

    Full Text Available Desert seed-harvester ants, genus Pogonomyrmex, are central place foragers that search for resources collectively. We quantify how seed harvesters exploit the spatial distribution of seeds to improve their rate of seed collection. We find that foraging rates are significantly influenced by the clumpiness of experimental seed baits. Colonies collected seeds from larger piles faster than randomly distributed seeds. We developed a method to compare foraging rates on clumped versus random seeds across three Pogonomyrmex species that differ substantially in forager population size. The increase in foraging rate when food was clumped in larger piles was indistinguishable across the three species, suggesting that species with larger colonies are no better than species with smaller colonies at collecting clumped seeds. These findings contradict the theoretical expectation that larger groups are more efficient at exploiting clumped resources, thus contributing to our understanding of the importance of the spatial distribution of food sources and colony size for communication and organization in social insects.

  4. Mesh size in Lichtenstein repair: a systematic review and meta-analysis to determine the importance of mesh size.

    Science.gov (United States)

    Seker, D; Oztuna, D; Kulacoglu, H; Genc, Y; Akcil, M

    2013-04-01

    Small mesh size has been recognized as one of the factors responsible for recurrence after Lichtenstein hernia repair due to insufficient coverage or mesh shrinkage. The Lichtenstein Hernia Institute recommends a 7 × 15 cm mesh that can be trimmed up to 2 cm from the lateral side. We performed a systematic review to determine surgeons' mesh size preference for the Lichtenstein hernia repair and made a meta-analysis to determine the effect of mesh size, mesh type, and length of follow-up time on recurrence. Two medical databases, PubMed and ISI Web of Science, were systematically searched using the key word "Lichtenstein repair." All full text papers were selected. Publications mentioning mesh size were brought for further analysis. A mesh surface area of 90 cm(2) was accepted as the threshold for defining the mesh as small or large. Also, a subgroup analysis for recurrence pooled proportion according to the mesh size, mesh type, and follow-up period was done. In total, 514 papers were obtained. There were no prospective or retrospective clinical studies comparing mesh size and clinical outcome. A total of 141 papers were duplicated in both databases. As a result, 373 papers were obtained. The full text was available in over 95 % of papers. Only 41 (11.2 %) papers discussed mesh size. In 29 studies, a mesh larger than 90 cm(2) was used. The most frequently preferred commercial mesh size was 7.5 × 15 cm. No papers mentioned the size of the mesh after trimming. There was no information about the relationship between mesh size and patient BMI. The pooled proportion in recurrence for small meshes was 0.0019 (95 % confidence interval: 0.007-0.0036), favoring large meshes to decrease the chance of recurrence. Recurrence becomes more marked when follow-up period is longer than 1 year (p < 0.001). Heavy meshes also decreased recurrence (p = 0.015). This systematic review demonstrates that the size of the mesh used in Lichtenstein hernia repair is rarely

  5. Organometallic approach to polymer-protected antibacterial silver nanoparticles: optimal nanoparticle size-selection for bacteria interaction

    Energy Technology Data Exchange (ETDEWEB)

    Crespo, Julian; Garcia-Barrasa, Jorge; Lopez-de-Luzuriaga, Jose M.; Monge, Miguel, E-mail: miguel.monge@unirioja.es; Olmos, M. Elena [Universidad de La Rioja, Centro de Investigacion en Sintesis Quimica (CISQ), Departamento de Quimica (Spain); Saenz, Yolanda; Torres, Carmen [Centro de Investigacion Biomedica de La Rioja, Area de Microbiologia Molecular (Spain)

    2012-12-15

    The optimal size-specific affinity of silver nanoparticles (Ag NPs) towards E. coli bacteria has been studied. For this purpose, Ag NPs coated with polyvinylpyrrolidone (PVP) and cellulose acetate (CA) have been prepared using an organometallic approach. The complex NBu{sub 4}[Ag(C{sub 6}F{sub 5}){sub 2}] has been treated with AgClO{sub 4} in a 1:1 molar ratio giving rise to the nanoparticle precursor [Ag(C{sub 6}F{sub 5})] in solution. Addition of an excess of PVP (1) or CA (2) and 5 h of reflux in tetrahydrofuran (THF) at 66 Degree-Sign C leads to Ag NPs of small size (4.8 {+-} 3.0 nm for PVP-Ag NPs and 3.0 {+-} 1.2 nm for CA-Ag NPs) that coexist in both cases with larger nanoparticles between 7 and 25 nm. Both nanomaterials display a high antibacterial effectiveness against E. coli. The TEM analysis of the nanoparticle-bacterial cell membrane interaction shows an optimal size-specific affinity for PVP-Ag NPs of 5.4 {+-} 0.7 nm in the presence of larger size silver nanoparticles.Graphical AbstractAn organometallic approach permits the synthesis of small size silver nanoparticles (ca 5 nm) as a main population in the presence of larger size nanoparticles. Optimal silver nanoparticle size-selection (5.4 nm) for the interaction with the bacterial membrane is achieved.

  6. An improved permanent magnet quadrupole design with larger good field region for high intensity proton linacs

    Energy Technology Data Exchange (ETDEWEB)

    Mathew, Jose V., E-mail: josev.mathew@gmail.com; Rao, S.V.L.S.; Krishnagopal, S.; Singh, P.

    2013-11-01

    The Low Energy High Intensity Proton Accelerator (LEHIPA), being developed at the Bhabha Atomic Research Centre (BARC) will produce a 20 MeV, 30 mA, continuous wave (CW) proton beam. At these low velocities, space-charge forces dominate, and could lead to larger beam sizes and beam halos. Hence in the design of the focusing lattice of the LEHIPA drift tube linac (DTL) using permanent magnet quadrupoles (PMQs), a larger good field region is preferred. Here we study, using the two dimensional (2D) and three dimensional (3D) simulation codes PANDIRA and RADIA, four different types of cylindrical PMQ designs: 16-segment trapezoidal Halbach configuration, bullet-nosed geometry and 8- and 16-segment rectangular geometries. The trapezoidal Halbach geometry is used in a variety of accelerators since it provides very high field gradients in small bores, while the bullet-nosed geometry, which is a combination of the trapezoidal and rectangular designs, is used in some DTLs. This study shows that a larger good field region is possible in the 16-segment rectangular design as compared to the Halbach and bullet-nosed designs, making it more attractive for high-intensity proton linacs. An improvement in good-field region by ∼16% over the Halbach design is obtained in the optimized 16-segment rectangular design, although the field gradient is lower by ∼20%. Tolerance studies show that the rectangular segment PMQ design is substantially less sensitive to the easy axis orientation errors and hence will be a better choice for DTLs. -- Highlights: • An improved permanent magnet quadrupole (PMQ) design with larger good field region is proposed. • We investigate four PMQ designs, including the widely used Halbach and bullet nosed designs. • Analytical calculations are backed by 2D as well as 3D numerical solvers, PANDIRA and RADIA. • The optimized 16 segment rectangular PMQ design is identified to exhibit the largest good field region. • The effect of easy axis orientation

  7. An improved permanent magnet quadrupole design with larger good field region for high intensity proton linacs

    International Nuclear Information System (INIS)

    Mathew, Jose V.; Rao, S.V.L.S.; Krishnagopal, S.; Singh, P.

    2013-01-01

    The Low Energy High Intensity Proton Accelerator (LEHIPA), being developed at the Bhabha Atomic Research Centre (BARC) will produce a 20 MeV, 30 mA, continuous wave (CW) proton beam. At these low velocities, space-charge forces dominate, and could lead to larger beam sizes and beam halos. Hence in the design of the focusing lattice of the LEHIPA drift tube linac (DTL) using permanent magnet quadrupoles (PMQs), a larger good field region is preferred. Here we study, using the two dimensional (2D) and three dimensional (3D) simulation codes PANDIRA and RADIA, four different types of cylindrical PMQ designs: 16-segment trapezoidal Halbach configuration, bullet-nosed geometry and 8- and 16-segment rectangular geometries. The trapezoidal Halbach geometry is used in a variety of accelerators since it provides very high field gradients in small bores, while the bullet-nosed geometry, which is a combination of the trapezoidal and rectangular designs, is used in some DTLs. This study shows that a larger good field region is possible in the 16-segment rectangular design as compared to the Halbach and bullet-nosed designs, making it more attractive for high-intensity proton linacs. An improvement in good-field region by ∼16% over the Halbach design is obtained in the optimized 16-segment rectangular design, although the field gradient is lower by ∼20%. Tolerance studies show that the rectangular segment PMQ design is substantially less sensitive to the easy axis orientation errors and hence will be a better choice for DTLs. -- Highlights: • An improved permanent magnet quadrupole (PMQ) design with larger good field region is proposed. • We investigate four PMQ designs, including the widely used Halbach and bullet nosed designs. • Analytical calculations are backed by 2D as well as 3D numerical solvers, PANDIRA and RADIA. • The optimized 16 segment rectangular PMQ design is identified to exhibit the largest good field region. • The effect of easy axis orientation

  8. Effect of initial grain size on dynamic recrystallization in high purity austenitic stainless steels

    International Nuclear Information System (INIS)

    El Wahabi, M.; Gavard, L.; Montheillet, F.; Cabrera, J.M.; Prado, J.M.

    2005-01-01

    The influence of initial microstructure on discontinuous dynamic recrystallization (DDRX) has been investigated by using high purity and ultra high purity austenitic stainless steels with various initial grain sizes. After uniaxial compression tests at constant strain rates and various temperatures, the steady state microstructure or the state corresponding to the maximum strain (ε = 1) attained in the test was analyzed by scanning electron microscopy aided with automated electron back scattering diffraction. Recrystallized grain size d rec and twin boundary fraction f TB measurements were carried out. The mechanical behavior was also investigated by comparing experimental stress-strain curves with various initial grain sizes. DDRX kinetics was described by the classical Avrami equation. It was concluded that larger initial grain sizes promoted a delay in the DDRX onset in the two alloys. It was also observed that the softening process progressed faster for smaller initial grain sizes. The effect of initial grain size is larger in the HP material and becomes more pronounced at low temperature

  9. Microcavity single virus detection and sizing with molecular sensitivity

    Science.gov (United States)

    Dantham, V. R.; Holler, S.; Kolchenko, V.; Wan, Z.; Arnold, S.

    2013-02-01

    We report the label-free detection and sizing of the smallest individual RNA virus, MS2 by a spherical microcavity. Mass of this virus is ~6 ag and produces a theoretical resonance shift ~0.25 fm upon adsorbing an individual virus at the equator of the bare microcavity, which is well below the r.m.s background noise of 2 fm. However, detection was accomplished with ease (S/N = 8, Q = 4x105) using a single dipole stimulated plasmonic-nanoshell as a microcavity wavelength shift enhancer. Analytical expressions based on the "reactive sensing principle" are developed to extract the radius of the virus from the measured signals. Estimated limit of detection for these experiments was ~0.4 ag or 240 kDa below the size of all known viruses, largest globular and elongated proteins [Phosphofructokinase (345 kDa) and Fibrinogen (390 kDa), respectively].

  10. Impact of aortic root size on left ventricular afterload and stroke volume.

    Science.gov (United States)

    Sahlén, Anders; Hamid, Nadira; Amanullah, Mohammed Rizwan; Fam, Jiang Ming; Yeo, Khung Keong; Lau, Yee How; Lam, Carolyn S P; Ding, Zee Pin

    2016-07-01

    The left ventricle (LV) ejects blood into the proximal aorta. Age and hypertension are associated with stiffening and dilation of the aortic root, typically viewed as indicative of adverse remodeling. Based on analytical considerations, we hypothesized that a larger aortic root should be associated with lower global afterload (effective arterial elastance, EA) and larger stroke volume (SV). Moreover, as antihypertensive drugs differ in their effect on central blood pressure, we examined the role of antihypertensive drugs for the relation between aortic root size and afterload. We studied a large group of patients (n = 1250; 61 ± 12 years; 78 % males; 64 % hypertensives) from a single-center registry with known or suspected coronary artery disease. Aortic root size was measured by echocardiography as the diameter of the tubular portion of the ascending aorta. LV outflow tract Doppler was used to record SV. In the population as a whole, after adjusting for key covariates in separate regression models, aortic root size was an independent determinant of both SV and EA. This association was found to be heterogeneous and stronger in patients taking a calcium channel blocker (CCB; 10.6 % of entire population; aortic root size accounted for 8 % of the explained variance of EA). Larger aortic root size is an independent determinant of EA and SV. This association was heterogeneous and stronger in patients on CCB therapy.

  11. Glenoid version and size: does gender, ethnicity, or body size play a role?

    Science.gov (United States)

    Piponov, Hristo Ivanov; Savin, David; Shah, Neal; Esposito, Domenic; Schwartz, Brian; Moretti, Vincent; Goldberg, Benjamin

    2016-11-01

    Variations in glenoid morphology among patients of different gender, body habitus, and ethnicity have been of interest for surgeons. Understanding these anatomical variations is a critical step in restoring normal glenohumeral structure during shoulder reconstruction surgery. Retrospective review of 108 patient shoulder CT scans was performed and glenoid version, AP diameter and height were measured. Statistical multiple regression models were used to investigate the ability of gender and ethnicity to predict glenoid AP diameter, height, and version independently of patient weight and height. The mean glenoid AP diameter was 24.7 ± 3.5, the mean glenoid height was 31.7 ± 3.7, and the mean glenoid version was 0.05 ± 9.05. According to our regression models, males would be expected to exhibit 8.4° more glenoid retroversion than females (p = 0.003) and have 2.9 mm larger glenoid height compared to females (p = 0.002). The predicted male glenoid AP diameter was 3.4 mm higher than that in females (p variations in glenoid size and version are observed among ethnicities, larger sample size ethnic groups will be necessary to explore the precise relations. Surgeons should consider gender and ethnic variations in the pre-operative planning and surgical restoration of the native glenohumeral relationship. Anatomic Study.

  12. Switching dynamics in reaction networks induced by molecular discreteness

    International Nuclear Information System (INIS)

    Togashi, Yuichi; Kaneko, Kunihiko

    2007-01-01

    To study the fluctuations and dynamics in chemical reaction processes, stochastic differential equations based on the rate equation involving chemical concentrations are often adopted. When the number of molecules is very small, however, the discreteness in the number of molecules cannot be neglected since the number of molecules must be an integer. This discreteness can be important in biochemical reactions, where the total number of molecules is not significantly larger than the number of chemical species. To elucidate the effects of such discreteness, we study autocatalytic reaction systems comprising several chemical species through stochastic particle simulations. The generation of novel states is observed; it is caused by the extinction of some molecular species due to the discreteness in their number. We demonstrate that the reaction dynamics are switched by a single molecule, which leads to the reconstruction of the acting network structure. We also show the strong dependence of the chemical concentrations on the system size, which is caused by transitions to discreteness-induced novel states

  13. Size-dependent modification of asteroid family Yarkovsky V-shapes

    Science.gov (United States)

    Bolin, B. T.; Morbidelli, A.; Walsh, K. J.

    2018-04-01

    Context. The thermal properties of the surfaces of asteroids determine the magnitude of the drift rate cause by the Yarkovsky force. In the general case of Main Belt asteroids, the Yarkovsky force is indirectly proportional to the thermal inertia, Γ. Aim. Following the proposed relationship between Γ and asteroid diameter D, we find that asteroids' Yarkovsky drift rates might have a more complex size dependence than previous thought, leading to a curved family V-shape boundary in semi-major axis, a, vs. 1/D space. This implies that asteroids are drifting faster at larger sizes than previously considered decreasing on average the known ages of asteroid families. Methods: The V-Shape curvature is determined for >25 families located throughout the Main Belt to quantify the Yarkovsky size-dependent drift rate. Results: We find that there is no correlation between family age and V-shape curvature. In addition, the V-shape curvature decreases for asteroid families with larger heliocentric distances suggesting that the relationship between Γ and D is weaker in the outer MB possibly due to homogenous surface roughness among family members.

  14. Finite-size scaling a collection of reprints

    CERN Document Server

    1988-01-01

    Over the past few years, finite-size scaling has become an increasingly important tool in studies of critical systems. This is partly due to an increased understanding of finite-size effects by analytical means, and partly due to our ability to treat larger systems with large computers. The aim of this volume was to collect those papers which have been important for this progress and which illustrate novel applications of the method. The emphasis has been placed on relatively recent developments, including the use of the &egr;-expansion and of conformal methods.

  15. Phospholipid-assisted synthesis of size-controlled gold nanoparticles

    International Nuclear Information System (INIS)

    He Peng; Zhu Xinyuan

    2007-01-01

    Morphology and size control of gold nanoparticles (AuNPs) by phospholipids (PLs) has been reported. It was found that gold entities could form nanostructures with different sizes controlled by PLs in an aqueous solution. During the preparation of 1.5 nm gold seeds, AuNPs were obtained from the reduction of gold complex by sodium borohydride and capped by citrate for stabilization. With the different ratios between seed solution and growth solution, which was composed by gold complex and PLs, gold seeds grew into larger nanoparticles step by step until enough large size up to 30 nm. The main discovery of this work is that common biomolecules, such as PLs can be used to control nanoparticle size. This conclusion has been confirmed by transmission electron micrographs, particle size analysis, and UV-vis spectra

  16. Size-dependent interaction of silica nanoparticles with lysozyme and bovine serum albumin proteins

    Science.gov (United States)

    Yadav, Indresh; Aswal, Vinod K.; Kohlbrecher, Joachim

    2016-05-01

    The interaction of three different sized (diameter 10, 18, and 28 nm) anionic silica nanoparticles with two model proteins—cationic lysozyme [molecular weight (MW) 14.7 kDa)] and anionic bovine serum albumin (BSA) (MW 66.4 kDa) has been studied by UV-vis spectroscopy, dynamic light scattering (DLS), and small-angle neutron scattering (SANS). The adsorption behavior of proteins on the nanoparticles, measured by UV-vis spectroscopy, is found to be very different for lysozyme and BSA. Lysozyme adsorbs strongly on the nanoparticles and shows exponential behavior as a function of lysozyme concentration irrespective of the nanoparticle size. The total amount of adsorbed lysozyme, as governed by the surface-to-volume ratio, increases on lowering the size of the nanoparticles for a fixed volume fraction of the nanoparticles. On the other hand, BSA does not show any adsorption for all the different sizes of the nanoparticles. Despite having different interactions, both proteins induce similar phase behavior where the nanoparticle-protein system transforms from one phase (clear) to two phase (turbid) as a function of protein concentration. The phase behavior is modified towards the lower concentrations for both proteins with increasing the nanoparticle size. DLS suggests that the phase behavior arises as a result of the nanoparticles' aggregation on the addition of proteins. The size-dependent modifications in the interaction potential, responsible for the phase behavior, have been determined by SANS data as modeled using the two-Yukawa potential accounting for the repulsive and attractive interactions in the systems. The protein-induced interaction between the nanoparticles is found to be short-range attraction for lysozyme and long-range attraction for BSA. The magnitude of attractive interaction irrespective of protein type is enhanced with increase in the size of the nanoparticles. The total (attractive+repulsive) potential leading to two-phase formation is found to be

  17. Recombining overlapping BACs into a single larger BAC

    Directory of Open Access Journals (Sweden)

    Huxley Clare

    2004-01-01

    Full Text Available Abstract Background BAC clones containing entire mammalian genes including all the transcribed region and long range controlling elements are very useful for functional analysis. Sequenced BACs are available for most of the human and mouse genomes and in many cases these contain intact genes. However, large genes often span more than one BAC, and single BACs covering the entire region of interest are not available. Here we describe a system for linking two or more overlapping BACs into a single clone by homologous recombination. Results The method was used to link a 61-kb insert carrying the final 5 exons of the human CFTR gene onto a 160-kb BAC carrying the first 22 exons. Two rounds of homologous recombination were carried out in the EL350 strain of bacteria which can be induced for the Red genes. In the first round, the inserts of the two overlapping BACs were subcloned into modified BAC vectors using homologous recombination. In the second round, the BAC to be added was linearised with the very rare-cutting enzyme I-PpoI and electroporated into recombination efficient EL350 bacteria carrying the other BAC. Recombined BACs were identified by antibiotic selection and PCR screening and 10% of clones contained the correctly recombined 220-kb BAC. Conclusion The system can be used to link the inserts from any overlapping BAC or PAC clones. The original orientation of the inserts is not important and desired regions of the inserts can be selected. The size limit for the fragments recombined may be larger than the 61 kb used here and multiple BACs in a contig could be combined by alternating use of the two pBACLink vectors. This system should be of use to many investigators wishing to carry out functional analysis on large mammalian genes which are not available in single BAC clones.

  18. Atomic structure and thermal stability of interfaces between metallic glass and embedding nano-crystallites revealed by molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Gao, X.Z.; Yang, G.Q.; Xu, B.; Qi, C.; Kong, L.T., E-mail: konglt@sjtu.edu.cn; Li, J.F.

    2015-10-25

    Molecular dynamics simulations were performed to investigate the atomic structure and thermal stability of interfaces formed between amorphous Cu{sub 50}Zr{sub 50} matrix and embedding B2 CuZr nano-crystallites. The interfaces are found to be rather abrupt, and their widths show negligible dependence on the nano-crystallite size. Local atomic configuration in the interfacial region is dominated by geometry characterized by Voronoi polyhedra <0,5,2,6> and <0,4,4,6>, and the contents of these polyhedra also exhibit apparent size dependence, which in turn results in an increasing trend in the interfacial energy against the nano-crystallite size. Annealing of the interface models at elevated temperatures will also enrich these characterizing polyhedra. While when the temperature is as high as the glass transition temperature of the matrix, growth of the nano-crystallites will be appreciable. The growth activation energy also shows size dependence, which is lower for larger nano-crystallites, suggesting that large nano-crystallites are prone to grow upon thermal disturbance. - Highlights: • Special clusters characterizing the local geometry are abundant in the interfaces. • Their content varies with the size of the embedding nano-crystallite. • In turn, size dependences in interfacial thermodynamics and kinetics are observed.

  19. Study on Relation between Hydrodynamic Feature Size of HPAM and Pore Size of Reservoir Rock in Daqing Oilfield

    Directory of Open Access Journals (Sweden)

    Qing Fang

    2015-01-01

    Full Text Available The flow mechanism of the injected fluid was studied by the constant pressure core displacement experiments in the paper. It is assumed under condition of the constant pressure gradient in deep formation based on the characteristic of pressure gradient distribution between the injection and production wells and the mobility of different polymer systems in deep reservoir. Moreover, the flow rate of steady stream was quantitatively analyzed and the critical flow pressure gradient of different injection parameters polymer solutions in different permeability cores was measured. The result showed that polymer hydrodynamic feature size increases with the increasing molecular weight. If the concentration of polymer solutions overlaps beyond critical concentration, then molecular chains entanglement will be occur and cause the augment of its hydrodynamic feature size. The polymer hydrodynamic feature size decreased as the salinity of the dilution water increased. When the median radius of the core pore and throat was 5–10 times of the polymer system hydrodynamic feature size, the polymer solution had a better compatibility with the microscopic pore structure of the reservoir. The estimation of polymer solutions mobility in the porous media can be used to guide the polymer displacement plan and select the optimum injection parameters.

  20. The 'Natural Laboratory', a tool for deciphering growth, lifetime and population dynamics in larger benthic foraminifera

    Science.gov (United States)

    Hohenegger, Johann

    2015-04-01

    The shells of symbiont-bearing larger benthic Foraminifera (LBF) represent the response to physiological requirements in dependence of environmental conditions. All compartments of the shell such as chambers and chamberlets accommodate the growth of the cell protoplasm and are adaptations for housing photosymbiotic algae. Investigations on the biology of LBF were predominantly based on laboratory studies. The lifetime of LBF under natural conditions is still unclear. LBF, which can build >100 chambers during their lifetime, are thought to live at least one year under natural conditions. This is supported by studies on population dynamics of eulittoral foraminifera. In species characterized by a time-restricted single reproduction period the mean size of specimens increases from small to large during lifetime simultaneously reducing individual number. This becomes more complex when two or more reproduction times are present within a one-year cycle leading to a mixture of abundant small individuals with few large specimens during the year, while keeping mean size more or less constant. This mixture is typical for most sublittoral megalospheric (gamonts or schizonts) LBF. Nothing is known on the lifetime of agamonts, the diploid asexually reproducing generation. In all hyaline LBF it is thought to be significantly longer than 1 year based on the large size and considering the mean chamber building rate of the gamont/schizonts. Observations on LBF under natural conditions have not been performed yet in the deeper sublittoral. This reflects the difficulties due to intense hydrodynamics that hinder deploying technical equipment for studies in the natural environment. Therefore, studying growth, lifetime and reproduction of sublittoral LBF under natural conditions can be performed using the so-called 'natural laboratory' in comparison with laboratory investigations. The best sampling method in the upper sublittoral from 5 to 70 m depth is by SCUBA diving. Irregular

  1. Evolution of brain region volumes during artificial selection for relative brain size.

    Science.gov (United States)

    Kotrschal, Alexander; Zeng, Hong-Li; van der Bijl, Wouter; Öhman-Mägi, Caroline; Kotrschal, Kurt; Pelckmans, Kristiaan; Kolm, Niclas

    2017-12-01

    The vertebrate brain shows an extremely conserved layout across taxa. Still, the relative sizes of separate brain regions vary markedly between species. One interesting pattern is that larger brains seem associated with increased relative sizes only of certain brain regions, for instance telencephalon and cerebellum. Till now, the evolutionary association between separate brain regions and overall brain size is based on comparative evidence and remains experimentally untested. Here, we test the evolutionary response of brain regions to directional selection on brain size in guppies (Poecilia reticulata) selected for large and small relative brain size. In these animals, artificial selection led to a fast response in relative brain size, while body size remained unchanged. We use microcomputer tomography to investigate how the volumes of 11 main brain regions respond to selection for larger versus smaller brains. We found no differences in relative brain region volumes between large- and small-brained animals and only minor sex-specific variation. Also, selection did not change allometric scaling between brain and brain region sizes. Our results suggest that brain regions respond similarly to strong directional selection on relative brain size, which indicates that brain anatomy variation in contemporary species most likely stem from direct selection on key regions. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  2. Optimization of the size and yield of graphene oxide sheets in the exfoliation step

    OpenAIRE

    Botas, Cristina; Pérez, A.M. (Ana); Álvarez, Patricia; Santamaría, Ricardo; Granda, Marcos; Blanco, Clara; Menéndez, Rosa

    2017-01-01

    In this paper we demonstrate that the yield and size of the graphene oxide sheets (GO) obtained by sonication of graphite oxide (GrO) can be optimized not only by selecting the appropriate exfoliation conditions but also as a function of the crystalline structure of the parent graphite. A larger crystal size in the parent graphite favors GrO exfoliation and yields larger sheets in shorter sonication times, independently of the oxygen content of the GrO. A maximum yield of GO is obtained in al...

  3. Microgravity Science Experiment of Marangoni Convection occurred in Larger Liquid Bridge on KIBO

    Science.gov (United States)

    Matsumoto, Satoshi; Yoda, Shinichi; Tanaka, Tetsuo

    Marangoni convection is a fluid motion induced by local variations of surface tension along a free surface which is caused by temperature and/or concentration differences. Marangoni convection plays important roll in such applications as crystal growth from melt, welding, con-tainerless material processing, and so on. One of the promising techniques to grow a high quality crystal is a floating-zone method which exists cylindrical melting part at heated region. This liquid part like a column is sustained between solid rods and it has free surface on the side. For investigation of Marangoni convection, a liquid bridge configuration with heated top and cooled bottom is often employed to simplify phenomena. Much work has been performed on Marangoni convection in the past, both experimentally and theoretically. Most of the ex-perimental investigations were conducted in normal gravity but some results from microgravity experiments are now available. However, problems to be solved are still remained in scientific view point. The effect of liquid bridge size on critical Marangoni number to determine the onset of oscillatory flow is one of important subjects. To investigate size effect, the experiment with changing wide range of diameter is needed. Under terrestrial conditions, large size of liquid bridge enhances to induce buoyancy convection. Much larger liquid bridge is deformed its shape or finally liquid bridge could not keep between disks because of its self-weight. So, microgravity experiment is required to make clear the size effect and to obtain precise data. We carried out Marangoni experiment under microgravity condition in Japanese Experiment Module "KIBO". A 50 mm diameter liquid bridge was formed and temperature difference between supporting rods was imposed to induce thermocapillary flow. Convective motion was observed in detail using several cameras, infrared camera and temperature sensors. Silicone oil of 5cSt was employed as a working fluid, which Prandtl

  4. Three-month-old human infants use vocal cues of body size.

    Science.gov (United States)

    Pietraszewski, David; Wertz, Annie E; Bryant, Gregory A; Wynn, Karen

    2017-06-14

    Differences in vocal fundamental ( F 0 ) and average formant ( F n ) frequencies covary with body size in most terrestrial mammals, such that larger organisms tend to produce lower frequency sounds than smaller organisms, both between species and also across different sex and life-stage morphs within species. Here we examined whether three-month-old human infants are sensitive to the relationship between body size and sound frequencies. Using a violation-of-expectation paradigm, we found that infants looked longer at stimuli inconsistent with the relationship-that is, a smaller organism producing lower frequency sounds, and a larger organism producing higher frequency sounds-than at stimuli that were consistent with it. This effect was stronger for fundamental frequency than it was for average formant frequency. These results suggest that by three months of age, human infants are already sensitive to the biologically relevant covariation between vocalization frequencies and visual cues to body size. This ability may be a consequence of developmental adaptations for building a phenotype capable of identifying and representing an organism's size, sex and life-stage. © 2017 The Author(s).

  5. Decadal Variation in Raindrop Size Distributions in Busan, Korea

    Directory of Open Access Journals (Sweden)

    Cheol-Hwan You

    2015-01-01

    Full Text Available This paper investigated the variability of raindrop size distributions (DSDs in Busan, Korea, using data from two different disdrometers: a precipitation occurrence sensor system (POSS and a particle size velocity (Parsivel optical disdrometer. DSDs were simulated using a gamma model to assess the intercomparability of these two techniques. Annual rainfall amount was higher in 2012 than in 2002, as were the annually averaged Dm (which was 0.1 mm greater in 2012 and the frequency of convective rain. Severe rainfall (greater than 20 mm h−1 occurred more frequently and with a larger Dm in 2012. The values of Dm from July, August, and December, 2012, were much greater than from other months when compared with 2002. Larger raindrops contributed to the higher rain rates that were observed in the morning during 2012, whereas relatively smaller raindrops dominated in the afternoon. These results suggest that the increase in raindrop size that has been observed in Busan may continue in the future; however, more research will be required if we are to fully understand this phenomenon. Rainfall variables are highly dependent on drop size and so should be recalculated using the newest DSDs to allow more accurate polarimetric radar rainfall estimation.

  6. Structure and size of ions electrochemically doped in conducting polymer

    Science.gov (United States)

    Kaneto, Keiichi; Hata, Fumito; Uto, Sadahito

    2018-05-01

    Among electroactive polymers (EAPs) for softactuators, conducting polymers have been intensively studied because of the large strain and stress caused by a low voltage operation. A larger deformation is desirable to extend their cycle life by reducing the operation voltage, and this is advantageous for their potential use in wider applications. The deformation is generated by the insertion of ions by electrochemical oxidation; hence, the magnitude of the strain depends on the bulkiness of the ions in the electrolytes. It is important, therefore, to clarify the structure and size of the ions during the electrochemical cycle, in order to achieve better performance of actuation. Anion and cation sizes (radii) in polypyrrole (PPy) film have been estimated using the precise measurement of strain against the amount of charge injected during the electrochemical cycles, assuming isotropic deformation of the film. The anion size was estimated using an anion-drive film, which was electrodeposited in TBABF4/methyl benzoate. The film was electrochemically cycled in sodium electrolytes, and the strain was measured simultaneously using a laser displacement meter. The cation size was obtained using a cation-drive film, being electropolymerized in aqueous dodecylbenzene sulfonic (DBS) acid. The cation-drive film was cycled in chloride electrolytes and measured the strain. The Cl-, Br-, NO3- , BF4- , and ClO4- radii were found to be approximately 235, 245, 250, 270 and 290 pm, respectively. The radii of K+, Na+ and Li+ were approximately 230, 237 and 274 pm, respectively. The results were discussed and took the crystalline ion radius and hydrated ion radius (Stokes radius) into consideration. It was found that the structure and size of the anions were slightly larger than the crystalline ion radius. Contrary to the anions, the cation radii were close to the hydrated ion radius, being larger than the crystalline ion radius.

  7. Meal size is a critical driver of weight gain in early childhood

    NARCIS (Netherlands)

    Syrad, H.; Llewellyn, C.H.; Johnson, L.; Boniface, D.; Jebb, S.A.; Jaarsveld, C.H.M. van; Wardle, J.

    2016-01-01

    Larger serving sizes and more frequent eating episodes have been implicated in the rising prevalence of obesity at a population level. This study examines the relative contributions of meal size and frequency to weight gain in a large sample of British children. Using 3-day diet diaries from 1939

  8. Rule reversal: Ecogeographical patterns of body size variation in the common treeshrew (Mammalia, Scandentia)

    Science.gov (United States)

    Sargis, Eric J.; Millien, Virginie; Woodman, Neal; Olson, Link E.

    2018-01-01

    There are a number of ecogeographical “rules” that describe patterns of geographical variation among organisms. The island rule predicts that populations of larger mammals on islands evolve smaller mean body size than their mainland counterparts, whereas smaller‐bodied mammals evolve larger size. Bergmann's rule predicts that populations of a species in colder climates (generally at higher latitudes) have larger mean body sizes than conspecifics in warmer climates (at lower latitudes). These two rules are rarely tested together and neither has been rigorously tested in treeshrews, a clade of small‐bodied mammals in their own order (Scandentia) broadly distributed in mainland Southeast Asia and on islands throughout much of the Sunda Shelf. The common treeshrew, Tupaia glis, is an excellent candidate for study and was used to test these two rules simultaneously for the first time in treeshrews. This species is distributed on the Malay Peninsula and several offshore islands east, west, and south of the mainland. Using craniodental dimensions as a proxy for body size, we investigated how island size, distance from the mainland, and maximum sea depth between the mainland and the islands relate to body size of 13 insular T. glis populations while also controlling for latitude and correlation among variables. We found a strong negative effect of latitude on body size in the common treeshrew, indicating the inverse of Bergmann's rule. We did not detect any overall difference in body size between the island and mainland populations. However, there was an effect of island area and maximum sea depth on body size among island populations. Although there is a strong latitudinal effect on body size, neither Bergmann's rule nor the island rule applies to the common treeshrew. The results of our analyses demonstrate the necessity of assessing multiple variables simultaneously in studies of ecogeographical rules.

  9. Molecular dynamics simulations of short-range force systems on 1024-node hypercubes

    International Nuclear Information System (INIS)

    Plimpton, S.J.

    1990-01-01

    In this paper, two parallel algorithms for classical molecular dynamics are presented. The first assigns each processor to a subset of particles; the second assigns each to a fixed region of 3d space. The algorithms are implemented on 1024-node hypercubes for problems characterized by short-range forces, diffusion (so that each particle's neighbors change in time), and problem size ranging from 250 to 10000 particles. Timings for the algorithms on the 1024-node NCUBE/ten and the newer NCUBE 2 hypercubes are given. The latter is found to be competitive with a CRAY-XMP, running an optimized serial algorithm. For smaller problems the NCUBE 2 and CRAY-XMP are roughly the same; for larger ones the NCUBE 2 is up to twice as fast. Parallel efficiencies of the algorithms and communication parameters for the two hypercubes are also examined

  10. Physician job satisfaction related to actual and preferred job size.

    Science.gov (United States)

    Schmit Jongbloed, Lodewijk J; Cohen-Schotanus, Janke; Borleffs, Jan C C; Stewart, Roy E; Schönrock-Adema, Johanna

    2017-05-11

    Job satisfaction is essential for physicians' well-being and patient care. The work ethic of long days and hard work that has been advocated for decades is acknowledged as a threat for physicians' job satisfaction, well-being, and patient safety. Our aim was to determine the actual and preferred job size of physicians and to investigate how these and the differences between them influence physicians' job satisfaction. Data were retrieved from a larger, longitudinal study among physicians starting medical training at Groningen University in 1982/83/92/93 (N = 597). Data from 506 participants (85%) were available for this study. We used regression analysis to investigate the influence of job size on physicians' job satisfaction (13 aspects) and ANOVA to examine differences in job satisfaction between physicians wishing to retain, reduce or increase job size. The majority of the respondents (57%) had an actual job size less than 1.0 FTE. More than 80% of all respondents preferred not to work full-time in the future. Respondents' average actual and preferred job sizes were .85 FTE and .81 FTE, respectively. On average, respondents who wished to work less (35% of respondents) preferred a job size reduction of 0.18 FTE and those who wished to work more (12%) preferred an increase in job size of 0.16 FTE. Job size influenced satisfaction with balance work-private hours most (β = -.351). Physicians who preferred larger job sizes were - compared to the other groups of physicians - least satisfied with professional accomplishments. A considerable group of physicians reported a gap between actual and preferred job size. Realizing physicians' preferences as to job size will hardly affect total workforce, but may greatly benefit individual physicians as well as their patients and society. Therefore, it seems time for a shift in work ethic.

  11. Self-assembled isoporous block copolymer membranes with tuned pore sizes

    KAUST Repository

    Yu, Haizhou

    2014-07-23

    The combination of nonsolvent-induced phase separation and the self-assembly of block copolymers can lead to asymmetric membranes with a thin highly ordered isoporous skin layer. The effective pore size of such membranes is usually larger than 15 nm. We reduced the pore size of these membranes by electroless gold deposition. We demonstrate that the pore sizes can be controlled precisely between 3 and 20 nm leading to a tunable sharp size discrimination in filtration processes. Besides fractionation of nanoparticles and biomaterials, controlled drug delivery is an attractive potential application. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Self-assembled isoporous block copolymer membranes with tuned pore sizes

    KAUST Repository

    Yu, Haizhou; Qiu, Xiaoyan; Nunes, Suzanapereira; Peinemann, Klaus-Viktor

    2014-01-01

    The combination of nonsolvent-induced phase separation and the self-assembly of block copolymers can lead to asymmetric membranes with a thin highly ordered isoporous skin layer. The effective pore size of such membranes is usually larger than 15 nm. We reduced the pore size of these membranes by electroless gold deposition. We demonstrate that the pore sizes can be controlled precisely between 3 and 20 nm leading to a tunable sharp size discrimination in filtration processes. Besides fractionation of nanoparticles and biomaterials, controlled drug delivery is an attractive potential application. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Prediction and validation of diffusion coefficients in a model drug delivery system using microsecond atomistic molecular dynamics simulation and vapour sorption analysis.

    Science.gov (United States)

    Forrey, Christopher; Saylor, David M; Silverstein, Joshua S; Douglas, Jack F; Davis, Eric M; Elabd, Yossef A

    2014-10-14

    Diffusion of small to medium sized molecules in polymeric medical device materials underlies a broad range of public health concerns related to unintended leaching from or uptake into implantable medical devices. However, obtaining accurate diffusion coefficients for such systems at physiological temperature represents a formidable challenge, both experimentally and computationally. While molecular dynamics simulation has been used to accurately predict the diffusion coefficients, D, of a handful of gases in various polymers, this success has not been extended to molecules larger than gases, e.g., condensable vapours, liquids, and drugs. We present atomistic molecular dynamics simulation predictions of diffusion in a model drug eluting system that represent a dramatic improvement in accuracy compared to previous simulation predictions for comparable systems. We find that, for simulations of insufficient duration, sub-diffusive dynamics can lead to dramatic over-prediction of D. We present useful metrics for monitoring the extent of sub-diffusive dynamics and explore how these metrics correlate to error in D. We also identify a relationship between diffusion and fast dynamics in our system, which may serve as a means to more rapidly predict diffusion in slowly diffusing systems. Our work provides important precedent and essential insights for utilizing atomistic molecular dynamics simulations to predict diffusion coefficients of small to medium sized molecules in condensed soft matter systems.

  14. Size-Selective Modes of Aeolian Transport on Earth and Mars

    Science.gov (United States)

    Swann, C.; Ewing, R. C.; Sherman, D. J.; McLean, C. J.

    2016-12-01

    Aeolian sand transport is a dominant driver of surface change and dust emission on Mars. Estimates of aeolian sand transport on Earth and Mars rely on terrestrial transport models that do not differentiate between transport modes (e.g., creep vs. saltation), which limits estimates of the critical threshold for transport and the total sand flux during a transport event. A gap remains in understanding how the different modes contribute to the total sand flux. Experiments conducted at the MARtian Surface WInd Tunnel separated modes of transport for uniform and mixed grain size surfaces at Earth and Martian atmospheric pressures. Crushed walnut shells with a density of 1.0 gm/cm3 were used. Experiments resolved grain size distributions for creeping and saltating grains over 3 uniform surfaces, U1, U2, and U3, with median grain sizes of 308 µm, 721 µm, and 1294 µm, and a mixed grain size surface, M1, with median grain sizes of 519 µm. A mesh trap located 5 cm above the test bed and a surface creep trap were deployed to capture particles moving as saltation and creep. Grains that entered the creep trap at angles ≥ 75° were categorized as moving in creep mode only. Only U1 and M1 surfaces captured enough surface creep at both Earth and Mars pressure for statistically significant grain size analysis. Our experiments show that size selective transport differs between Earth and Mars conditions. The median grain size of particles moving in creep for both uniform and mixed surfaces are larger under Earth conditions. (U1Earth = 385 µm vs. U1Mars = 355 µm; M1Earth = 762 vs. M1Mars = 697 µm ). However, particles moving in saltation were larger under Mars conditions (U1Earth = 282 µm; U1Mars = 309 µm; M1Earth = 347 µm; M1Mars = 454 µm ). Similar to terrestrial experiments, the median size of surface creep is larger than the median grain size of saltation. Median sizes of U1, U2, U3 at Mars conditions for creep was 355 µm, 774 µm and 1574 µm. Saltation at Mars

  15. Clutch frequency affects the offspring size-number trade-off in lizards.

    Directory of Open Access Journals (Sweden)

    Zheng Wang

    2011-01-01

    Full Text Available Studies of lizards have shown that offspring size cannot be altered by manipulating clutch size in species with a high clutch frequency. This raises a question of whether clutch frequency has a key role in influencing the offspring size-number trade-off in lizards.To test the hypothesis that females reproducing more frequently are less likely to tradeoff offspring size against offspring number, we applied the follicle ablation technique to female Eremias argus (Lacertidae from Handan (HD and Gonghe (GH, the two populations that differ in clutch frequency. Follicle ablation resulted in enlargement of egg size in GH females, but not in HD females. GH females switched from producing a larger number of smaller eggs in the first clutch to a smaller number of larger eggs in the second clutch; HD females showed a similar pattern of seasonal shifts in egg size, but kept clutch size constant between the first two clutches. Thus, the egg size-number trade-off was evident in GH females, but not in HD females.As HD females (mean  = 3.1 clutches per year reproduce more frequently than do GH females (mean  = 1.6 clutches per year, our data therefore validate the hypothesis tested. Our data also provide an inference that maximization of maternal fitness could be achieved in females by diverting a large enough, rather than a higher-than-usual, fraction of the available energy to individual offspring in a given reproductive episode.

  16. Measuring agglomerate size distribution and dependence of localized surface plasmon resonance absorbance on gold nanoparticle agglomerate size using analytical ultracentrifugation.

    Science.gov (United States)

    Zook, Justin M; Rastogi, Vinayak; Maccuspie, Robert I; Keene, Athena M; Fagan, Jeffrey

    2011-10-25

    Agglomeration of nanoparticles during measurements in relevant biological and environmental media is a frequent problem in nanomaterial property characterization. The primary problem is typically that any changes to the size distribution can dramatically affect the potential nanotoxicity or other size-determined properties, such as the absorbance signal in a biosensor measurement. Herein we demonstrate analytical ultracentrifugation (AUC) as a powerful method for measuring two critical characteristics of nanoparticle (NP) agglomerates in situ in biological media: the NP agglomerate size distribution, and the localized surface plasmon resonance (LSPR) absorbance spectrum of precise sizes of gold NP agglomerates. To characterize the size distribution, we present a theoretical framework for calculating the hydrodynamic diameter distribution of NP agglomerates from their sedimentation coefficient distribution. We measure sedimentation rates for monomers, dimers, and trimers, as well as for larger agglomerates with up to 600 NPs. The AUC size distributions were found generally to be broader than the size distributions estimated from dynamic light scattering and diffusion-limited colloidal aggregation theory, an alternative bulk measurement method that relies on several assumptions. In addition, the measured sedimentation coefficients can be used in nanotoxicity studies to predict how quickly the agglomerates sediment out of solution under normal gravitational forces, such as in the environment. We also calculate the absorbance spectra for monomer, dimer, trimer, and larger gold NP agglomerates up to 600 NPs, to enable a better understanding of LSPR biosensors. Finally, we validate a new method that uses these spectra to deconvolute the net absorbance spectrum of an unknown bulk sample and approximate the proportions of monomers, dimers, and trimers in a polydisperse sample of small agglomerates, so that every sample does not need to be measured by AUC. These results

  17. Size, rarity and charisma: valuing African wildlife trophies.

    Directory of Open Access Journals (Sweden)

    Paul J Johnson

    Full Text Available We explore variation in the prices paid by recreational hunters of trophy animals in Africa and its possible causes, including perceived rarity. Previous work has raised the possibility that extinction can result if demand rises fast enough as a species becomes rarer. We attempt to disentangle this from other inter-correlated influences affecting price. Species with larger body sizes and larger trophies were more valuable. Value increased less steeply as a function of size for bovids than for felids and the effect was consistent across countries. Power laws, ubiquitous in physical and social systems, described the trends. The exponent was approximately 0.4 for bovids, compared with approximately 1.0 for felids. Rarity (as indexed by IUCN score influenced the value of bovid trophies - price was higher for species in categories denoting higher global threat. There was substantial variation in price among and within families not explained by either size or rarity. This may be attributable to a 'charisma' effect, which seems likely to be a general attribute of human perceptions of wildlife. Species where prices were higher than predicted by size or rarity are ranked high in published accounts of desirability by hunters. We conclude that the valuation of these species is explicable to a large extent by body size and perceived rarity, and that differences in valuation between taxonomic groups are related to less easily quantified 'charisma' effects. These findings are relevant for conservationists considering the threat status of species exploited in open access markets, and where license quotas are adjusted in response to changes in perceived rarity.

  18. Electron screening in molecular fusion reactions

    International Nuclear Information System (INIS)

    Shoppa, T.D.

    1996-01-01

    Recent laboratory experiments have measured fusion cross sections at center-of-mass energies low enough for the effects of atomic and molecular electrons to be important. To extract the cross section for bare nuclei from these data (as required for astrophysical applications), it is necessary to understand these screening effects. We study electron screening effects in the low-energy collisions of Z=1 nuclei with hydrogen molecules. Our model is based on a dynamical evolution of the electron wave functions within the TDHF scheme, while the motion of the nuclei is treated classically. We find that at the currently accessible energies the screening effects depend strongly on the molecular orientation. The screening is found to be larger for molecular targets than for atomic targets, due to the reflection symmetry in the latter. The results agree fairly well with data measured for deuteron collisions on molecular deuterium and tritium targets. (orig.)

  19. Fully integrated high-speed intravascular optical coherence tomography/near-infrared fluorescence structural/molecular imaging in vivo using a clinically available near-infrared fluorescence-emitting indocyanine green to detect inflamed lipid-rich atheromata in coronary-sized vessels.

    Science.gov (United States)

    Lee, Sunki; Lee, Min Woo; Cho, Han Saem; Song, Joon Woo; Nam, Hyeong Soo; Oh, Dong Joo; Park, Kyeongsoon; Oh, Wang-Yuhl; Yoo, Hongki; Kim, Jin Won

    2014-08-01

    Lipid-rich inflamed coronary plaques are prone to rupture. The purpose of this study was to assess lipid-rich inflamed plaques in vivo using fully integrated high-speed optical coherence tomography (OCT)/near-infrared fluorescence (NIRF) molecular imaging with a Food and Drug Administration-approved indocyanine green (ICG). An integrated high-speed intravascular OCT/NIRF imaging catheter and a dual-modal OCT/NIRF system were constructed based on a clinical OCT platform. For imaging lipid-rich inflamed plaques, the Food and Drug Administration-approved NIRF-emitting ICG (2.25 mg/kg) or saline was injected intravenously into rabbit models with experimental atheromata induced by balloon injury and 12- to 14-week high-cholesterol diets. Twenty minutes after injection, in vivo OCT/NIRF imaging of the infrarenal aorta and iliac arteries was acquired only under contrast flushing through catheter (pullback speed up to ≤20 mm/s). NIRF signals were strongly detected in the OCT-visualized atheromata of the ICG-injected rabbits. The in vivo NIRF target-to-background ratio was significantly larger in the ICG-injected rabbits than in the saline-injected controls (Pfluorescence reflectance imaging, which correlated well with the in vivo target-to-background ratios (Pfluorescence microscopy, and histopathology also corroborated the in vivo imaging findings. Integrated OCT/NIRF structural/molecular imaging with a Food and Drug Administration -approved ICG accurately identified lipid-rich inflamed atheromata in coronary-sized vessels. This highly translatable dual-modal imaging approach could enhance our capabilities to detect high-risk coronary plaques. © 2014 American Heart Association, Inc.

  20. Black hole mass measurement using molecular gas kinematics: what ALMA can do

    Science.gov (United States)

    Yoon, Ilsang

    2017-04-01

    We study the limits of the spatial and velocity resolution of radio interferometry to infer the mass of supermassive black holes (SMBHs) in galactic centres using the kinematics of circum-nuclear molecular gas, by considering the shapes of the galaxy surface brightness profile, signal-to-noise ratios (S/Ns) of the position-velocity diagram (PVD) and systematic errors due to the spatial and velocity structure of the molecular gas. We argue that for fixed galaxy stellar mass and SMBH mass, the spatial and velocity scales that need to be resolved increase and decrease, respectively, with decreasing Sérsic index of the galaxy surface brightness profile. We validate our arguments using simulated PVDs for varying beam size and velocity channel width. Furthermore, we consider the systematic effects on the inference of the SMBH mass by simulating PVDs including the spatial and velocity structure of the molecular gas, which demonstrates that their impacts are not significant for a PVD with good S/N unless the spatial and velocity scale associated with the systematic effects are comparable to or larger than the angular resolution and velocity channel width of the PVD from pure circular motion. Also, we caution that a bias in a galaxy surface brightness profile owing to the poor resolution of a galaxy photometric image can largely bias the SMBH mass by an order of magnitude. This study shows the promise and the limits of ALMA observations for measuring SMBH mass using molecular gas kinematics and provides a useful technical justification for an ALMA proposal with the science goal of measuring SMBH mass.

  1. Penis size interacts with body shape and height to influence male attractiveness.

    Science.gov (United States)

    Mautz, Brian S; Wong, Bob B M; Peters, Richard A; Jennions, Michael D

    2013-04-23

    Compelling evidence from many animal taxa indicates that male genitalia are often under postcopulatory sexual selection for characteristics that increase a male's relative fertilization success. There could, however, also be direct precopulatory female mate choice based on male genital traits. Before clothing, the nonretractable human penis would have been conspicuous to potential mates. This observation has generated suggestions that human penis size partly evolved because of female choice. Here we show, based upon female assessment of digitally projected life-size, computer-generated images, that penis size interacts with body shape and height to determine male sexual attractiveness. Positive linear selection was detected for penis size, but the marginal increase in attractiveness eventually declined with greater penis size (i.e., quadratic selection). Penis size had a stronger effect on attractiveness in taller men than in shorter men. There was a similar increase in the positive effect of penis size on attractiveness with a more masculine body shape (i.e., greater shoulder-to-hip ratio). Surprisingly, larger penis size and greater height had almost equivalent positive effects on male attractiveness. Our results support the hypothesis that female mate choice could have driven the evolution of larger penises in humans. More broadly, our results show that precopulatory sexual selection can play a role in the evolution of genital traits.

  2. Transmembrane molecular transport during versus after extremely large, nanosecond electric pulses.

    Science.gov (United States)

    Smith, Kyle C; Weaver, James C

    2011-08-19

    Recently there has been intense and growing interest in the non-thermal biological effects of nanosecond electric pulses, particularly apoptosis induction. These effects have been hypothesized to result from the widespread creation of small, lipidic pores in the plasma and organelle membranes of cells (supra-electroporation) and, more specifically, ionic and molecular transport through these pores. Here we show that transport occurs overwhelmingly after pulsing. First, we show that the electrical drift distance for typical charged solutes during nanosecond pulses (up to 100 ns), even those with very large magnitudes (up to 10 MV/m), ranges from only a fraction of the membrane thickness (5 nm) to several membrane thicknesses. This is much smaller than the diameter of a typical cell (∼16 μm), which implies that molecular drift transport during nanosecond pulses is necessarily minimal. This implication is not dependent on assumptions about pore density or the molecular flux through pores. Second, we show that molecular transport resulting from post-pulse diffusion through minimum-size pores is orders of magnitude larger than electrical drift-driven transport during nanosecond pulses. While field-assisted charge entry and the magnitude of flux favor transport during nanosecond pulses, these effects are too small to overcome the orders of magnitude more time available for post-pulse transport. Therefore, the basic conclusion that essentially all transmembrane molecular transport occurs post-pulse holds across the plausible range of relevant parameters. Our analysis shows that a primary direct consequence of nanosecond electric pulses is the creation (or maintenance) of large populations of small pores in cell membranes that govern post-pulse transmembrane transport of small ions and molecules. Copyright © 2011 Elsevier Inc. All rights reserved.

  3. Predicting the performance of molecularly imprinted polymers: Selective extraction of caffeine by molecularly imprinted solid phase extraction

    Energy Technology Data Exchange (ETDEWEB)

    Farrington, Keith [School of Chemical Sciences, Dublin City University, Glasnevin, Dublin 9 (Ireland); Magner, Edmond [Materials and Surface Science Institute, Chemical and Environmental Sciences Department, University of Limerick, Limerick (Ireland); Regan, Fiona [School of Chemical Sciences, Dublin City University, Glasnevin, Dublin 9 (Ireland)]. E-mail: fiona.regan@dcu.ie

    2006-04-27

    A rational design approach was taken to the planning and synthesis of a molecularly imprinted polymer capable of extracting caffeine (the template molecule) from a standard solution of caffeine and further from a food sample containing caffeine. Data from NMR titration experiments in conjunction with a molecular modelling approach was used in predicting the relative ratios of template to functional monomer and furthermore determined both the choice of solvent (porogen) and the amount used for the study. In addition the molecular modelling program yielded information regarding the thermodynamic stability of the pre-polymerisation complex. Post-polymerisation analysis of the polymer itself by analysis of the pore size distribution by BET yielded significant information regarding the nature of the size and distribution of the pores within the polymer matrix. Here is proposed a stepwise procedure for the development and testing of a molecularly imprinted polymer using a well-studied compound-caffeine as a model system. It is shown that both the physical characteristics of a molecularly imprinted polymer (MIP) and the analysis of the pre-polymerisation complex can yield vital information, which can predict how well a given MIP will perform.

  4. Predicting the performance of molecularly imprinted polymers: Selective extraction of caffeine by molecularly imprinted solid phase extraction

    International Nuclear Information System (INIS)

    Farrington, Keith; Magner, Edmond; Regan, Fiona

    2006-01-01

    A rational design approach was taken to the planning and synthesis of a molecularly imprinted polymer capable of extracting caffeine (the template molecule) from a standard solution of caffeine and further from a food sample containing caffeine. Data from NMR titration experiments in conjunction with a molecular modelling approach was used in predicting the relative ratios of template to functional monomer and furthermore determined both the choice of solvent (porogen) and the amount used for the study. In addition the molecular modelling program yielded information regarding the thermodynamic stability of the pre-polymerisation complex. Post-polymerisation analysis of the polymer itself by analysis of the pore size distribution by BET yielded significant information regarding the nature of the size and distribution of the pores within the polymer matrix. Here is proposed a stepwise procedure for the development and testing of a molecularly imprinted polymer using a well-studied compound-caffeine as a model system. It is shown that both the physical characteristics of a molecularly imprinted polymer (MIP) and the analysis of the pre-polymerisation complex can yield vital information, which can predict how well a given MIP will perform

  5. Portion distortion: typical portion sizes selected by young adults.

    Science.gov (United States)

    Schwartz, Jaime; Byrd-Bredbenner, Carol

    2006-09-01

    The incidence of obesity has increased in parallel with increasing portion sizes of individually packaged and ready-to-eat prepared foods as well as foods served at restaurants. Portion distortion (perceiving large portion sizes as appropriate amounts to eat at a single eating occasion) may contribute to increasing energy intakes and expanding waistlines. The purpose of this study was to determine typical portion sizes that young adults select, how typical portion sizes compare with reference portion sizes (based in this study on the Nutrition Labeling and Education Act's quantities of food customarily eaten per eating occasion), and whether the size of typical portions has changed over time. Young adults (n=177, 75% female, age range 16 to 26 years) at a major northeastern university. Participants served themselves typical portion sizes of eight foods at breakfast (n=63) or six foods at lunch or dinner (n=62, n=52, respectively). Typical portion-size selections were unobtrusively weighed. A unit score was calculated by awarding 1 point for each food with a typical portion size that was within 25% larger or smaller than the reference portion; larger or smaller portions were given 0 points. Thus, each participant's unit score could range from 0 to 8 at breakfast or 0 to 6 at lunch and dinner. Analysis of variance or t tests were used to determine whether typical and reference portion sizes differed, and whether typical portion sizes changed over time. Mean unit scores (+/-standard deviation) were 3.63+/-1.27 and 1.89+/-1.14, for breakfast and lunch/dinner, respectively, indicating little agreement between typical and reference portion sizes. Typical portions sizes in this study tended to be significantly different from those selected by young adults in a similar study conducted 2 decades ago. Portion distortion seems to affect the portion sizes selected by young adults for some foods. This phenomenon has the potential to hinder weight loss, weight maintenance, and

  6. Uniform molecularly imprinted microspheres and nanoparticles prepared by precipitation polymerization: The control of particle size suitable for different analytical applications

    International Nuclear Information System (INIS)

    Yoshimatsu, Keiichi; Reimhult, Kristina; Krozer, Anatol; Mosbach, Klaus; Sode, Koji; Ye Lei

    2007-01-01

    Molecularly imprinted polymers (MIPs) are being increasingly used as selective adsorbents in different analytical applications. To satisfy the different application purposes, MIPs with well controlled physical forms in different size ranges are highly desirable. For examples, MIP nanoparticles are very suitable to be used to develop binding assays and for microfluidic separations, whereas MIP beads with diameter of 1.5-3 μm can be more appropriate to use in new analytical liquid chromatography systems. Previous studies have demonstrated that imprinted microspheres and nanoparticles can be synthesized using a simple precipitation polymerization method. Despite that the synthetic method is straightforward, the final particle size obtained has been difficult to adjust for a given template. In this work, we initiated to study new synthetic conditions to obtain MIP beads with controllable size in the nano- to micro-meter range, using racemic propranolol as a model template. Varying the composition of the cross-linking monomer allowed the particle size of the MIP beads to be altered in the range of 130 nm to 2.4 μm, whereas the favorable binding property of the imprinted beads remained intact. The chiral recognition sites were further characterized with equilibrium binding analysis using tritium-labeled (S)-propranolol as a tracer. In general, the imprinted sites displayed a high chiral selectivity: the apparent affinity of the (S)-imprinted sites for (S)-propranolol was 20 times that of for (R)-propranolol. Compared to previously reported irregular particles, the chiral selectivity of competitive radioligand binding assays developed from the present imprinted beads has been increased by six to seven folds in an optimized aqueous solvent

  7. Gold Nanoparticles Size Design and Control by Poly(N,N′-diethylaminoethyl methacrylate

    Directory of Open Access Journals (Sweden)

    Norma A. Cortez-Lemus

    2015-01-01

    Full Text Available Poly(N,N′-diethylaminoethyl methacrylate (PDEAEM with different molecular weights was used to stabilize gold nanoparticles (AuNPs obtained by in situ reduction of tetrachloroauric acid using citrates under acidic conditions and in organic/alcoholic medium. The influence of the pH value on gold nanoparticle size in the presence of PDEAEM was investigated. Results show that the pH of the reacting mixture has a dramatic effect on the size, polydispersity, and morphology of the resulting AuNPs. Moreover, the size of the nanoparticles (NPs may be modified by changing the solution’s pH or by changing the solvent type. Electron microscope images showed that the sizes of AuNPs coated with PDEAEM were not sensitive to the variation of the polymer molecular weight in the range between 9000 and 29300 g/mol; however their aggregation behavior depended strongly on the polymer molecular weight as revealed by dynamic light scattering studies. AuNPs stabilized with PDEAEM (AuNP@PDEAEM are stable in water at acidic pH and in organic polar solvents.

  8. CT provides precise size assessment of implanted titanium alloy pedicle screws.

    Science.gov (United States)

    Elliott, Michael J; Slakey, Joseph B

    2014-05-01

    After performing instrumented spinal fusion with pedicle screws, postoperative imaging using CT to assess screw position may be necessary. Stainless steel implants produce significant metal artifact on CT, and the degree of distortion is at least partially dependent on the cross-sectional area of the implanted device. If the same effect occurs with titanium alloy implants, ability to precisely measure proximity of screws to adjacent structures may be adversely affected as screw size increases. We therefore asked whether (1) CT provides precise measurements of true screw widths; and (2) precision degrades based on the size of the titanium implant imaged. CT scans performed on 20 patients after instrumented spinal fusion for scoliosis were reviewed. The sizes of 151 titanium alloy pedicle screws were measured and compared with known screw size. The amount of metal bloom artifact was determined for each of the four screw sizes. ANOVA with Tukey's post hoc test were performed to evaluate differences in scatter, and Spearman's rho coefficient was used to measure relationship between screw size and scatter. All screws measured larger than their known size, but even with larger 7-mm screws the size differential was less than 1 mm. The four different screw sizes produced scatter amounts that were different from each other (p titanium alloy pedicle screws produces minimal artifact, thus making this the preferred imaging modality to assess screw position after surgery. Although the amount of artifact increases with the volume of titanium present, the degree of distortion is minimal and is usually less than 1 mm.

  9. Increased Back-Bonding Explains Step-Edge Reactivity and Particle Size Effect for CO Activation on Ru Nanoparticles.

    Science.gov (United States)

    Foppa, Lucas; Copéret, Christophe; Comas-Vives, Aleix

    2016-12-28

    Carbon monoxide is a ubiquitous molecule, a key feedstock and intermediate in chemical processes. Its adsorption and activation, typically carried out on metallic nanoparticles (NPs), are strongly dependent on the particle size. In particular, small NPs, which in principle contain more corner and step-edge atoms, are surprisingly less reactive than larger ones. Hereby, first-principles calculations on explicit Ru NP models (1-2 nm) show that both small and large NPs can present step-edge sites (e.g., B 5 and B 6 sites). However, such sites display strong particle-size-dependent reactivity because of very subtle differences in local chemical bonding. State-of-the-art crystal orbital Hamilton population analysis allows a detailed molecular orbital picture of adsorbed CO on step-edges, which can be classified as flat (η 1 coordination) and concave (η 2 coordination) sites. Our analysis shows that the CO π-metal d π hybrid band responsible for the electron back-donation is better represented by an oxygen lone pair on flat sites, whereas it is delocalized on both C and O atoms on concave sites, increasing the back-bonding on these sites compared to flat step-edges or low-index surface sites. The bonding analysis also rationalizes why CO cleavage is easier on step-edge sites of large NPs compared to small ones irrespective of the site geometry. The lower reactivity of small NPs is due to the smaller extent of the Ru-O interaction in the η 2 adsorption mode, which destabilizes the η 2 transition-state structure for CO direct cleavage. Our findings provide a molecular understanding of the reactivity of CO on NPs, which is consistent with the observed particle size effect.

  10. Molecular modeling study of agglomeration of [6,6]-phenyl-C61-butyric acid methyl ester in solvents.

    Science.gov (United States)

    Mortuza, S M; Banerjee, Soumik

    2012-12-28

    The molecular interactions between solvent and nanoparticles during photoactive layer formation in organic photovoltaic (OPV) cells influence the morphology of the photoactive layer and hence determine the power conversion efficiency. Prediction of optimal synthesis parameters in OPVs, such as choice of solvent, processing temperature, and nanoparticle concentration, requires fundamental understanding of the mechanisms that govern the agglomeration of nanoparticles in solvents. In this study, we used molecular dynamics simulations to simulate a commonly used organic nanoparticle, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM), in various solvents to correlate solvent-nanoparticle interactions with the size of the agglomerate structure of PCBM. We analyzed the effects of concentration of PCBM and operating temperature on the molecular rearrangement and agglomeration of PCBM in three solvents: (i) toluene, (ii) indane, and (iii) toluene-indane mixture. We evaluated the agglomeration behavior of PCBM by determining sizes of the largest clusters of PCBM and the corresponding size distributions. To obtain further insight into the agglomerate structure of PCBMs, we evaluated radial distribution functions (RDFs) and coordination numbers of the various moieties of PCBMs with respect to solvent atoms as well as with respect to that of other PCBMs. Our simulations demonstrate that PCBMs form larger clusters in toluene while they are relatively dispersed in indane, which indicates the greater solubility of PCBM in indane than in toluene. In toluene-indane mixture, PCBMs are clustered to a greater extent than in indane and less than that in toluene. To correlate agglomerate size to nanoparticle-solvent interactions, we also evaluated the potential of mean force (PMF) of the fullerene moiety of PCBM in toluene and indane. Our results also show that the cluster size of PCBM molecules increases with the increase of concentration of PCBM and the processing temperature. To

  11. Atomic size effect on critical cooling rate and glass formation

    International Nuclear Information System (INIS)

    Jalali, Payman; Li Mo

    2005-01-01

    Atomic size effect on critical cooling rate and glass formability in a model binary system is investigated using molecular dynamics simulation. To isolate atomic size effect from the rest of the factors that critically influence the glass formation, a hard sphere model is employed in conjunction with a newly developed densification method. The glass formability is defined as a set of optimal conditions that result in the slowest cooling rate of the glass-forming liquid. Critical cooling rates are identified from extensive molecular dynamics simulations. A kinetic glass-forming diagram is mapped out that marks the boundary between the glass-forming regions and competing crystalline phases in terms of the parameters of the atomic size ratio and alloy concentration. It is found that the potency of the atomic size difference on glass formation is influenced greatly by the competing metastable and equilibrium crystalline phases in the system, and the kinetic processes leading to the formation of these phases. The mechanisms of the atomic size effect on topological instability of crystal packing and glass formation are discussed

  12. On size effects in fracture

    International Nuclear Information System (INIS)

    Sinclair, G.B.

    1985-01-01

    This paper discusses the dependence of fracture stress on size. This conclusion is based on classical energy arguments. For an in-plane scaled specimen pair, the larger the specimen the smaller the fracture stress. In contrast the same theory gives a different dependence for out-of-plane specimen and the dependence involves plane stress, strain, fracture stresses and Poisson's ratio. The objective of this paper is to examine how well these predictions are actually complied with

  13. Early exposure to nonlethal predation risk by size-selective predators increases somatic growth and decreases size at adulthood in threespined sticklebacks

    NARCIS (Netherlands)

    Bell, A. M.; Dingemanse, N. J.; Hankison, S. J.; Langenhof, M. B. W.; Rollins, K.

    Predation has an important influence on life history traits in many organisms, especially when they are young. When cues of trout were present, juvenile sticklebacks grew faster. The increase in body size as a result of exposure to cues of predators was adaptive because larger individuals were more

  14. Molecular Structure of Human-Liver Glycogen.

    Directory of Open Access Journals (Sweden)

    Bin Deng

    Full Text Available Glycogen is a highly branched glucose polymer which is involved in maintaining blood-sugar homeostasis. Liver glycogen contains large composite α particles made up of linked β particles. Previous studies have shown that the binding which links β particles into α particles is impaired in diabetic mice. The present study reports the first molecular structural characterization of human-liver glycogen from non-diabetic patients, using transmission electron microscopy for morphology and size-exclusion chromatography for the molecular size distribution; the latter is also studied as a function of time during acid hydrolysis in vitro, which is sensitive to certain structural features, particularly glycosidic vs. proteinaceous linkages. The results are compared with those seen in mice and pigs. The molecular structural change during acid hydrolysis is similar in each case, and indicates that the linkage of β into α particles is not glycosidic. This result, and the similar morphology in each case, together imply that human liver glycogen has similar molecular structure to those of mice and pigs. This knowledge will be useful for future diabetes drug targets.

  15. Food photographs in portion size estimation among adolescent Mozambican girls.

    Science.gov (United States)

    Korkalo, Liisa; Erkkola, Maijaliisa; Fidalgo, Lourdes; Nevalainen, Jaakko; Mutanen, Marja

    2013-09-01

    To assess the validity of food photographs in portion size estimation among adolescent girls in Mozambique. The study was carried out in preparation for the larger ZANE study, which used the 24 h dietary recall method. Life-sized photographs of three portion sizes of two staple foods and three sauces were produced. Participants ate weighed portions of one staple food and one sauce. After the meal, they were asked to estimate the amount of food with the aid of the food photographs. Zambezia Province, Mozambique. Ninety-nine girls aged 13–18 years. The mean differences between estimated and actual portion sizes relative to the actual portion size ranged from 219% to 8% for different foods. The respective mean difference for all foods combined was 25% (95% CI 212, 2 %). Especially larger portions of the staple foods were often underestimated. For the staple foods, between 62% and 64% of the participants were classified into the same thirds of the distribution of estimated and actual food consumption and for sauces, the percentages ranged from 38% to 63%. Bland–Altman plots showed wide limits of agreement. Using life-sized food photographs among adolescent Mozambican girls resulted in a rather large variation in the accuracy of individuals’ estimates. The ability to rank individuals according to their consumption was, however, satisfactory for most foods. There seems to be a need to further develop and test food photographs used in different populations in Sub-Saharan Africa to improve the accuracy of portion size estimates.

  16. When the proton becomes larger

    CERN Multimedia

    CERN Bulletin

    2011-01-01

    The TOTEM experiment at the LHC has just confirmed that, at high energy, protons behave as if they were becoming larger. In more technical terms, their total cross-section – a parameter linked to the proton-proton interaction probability – increases with energy. This phenomenon, expected from previous measurements performed at much lower energy, has now been confirmed for the first time at the LHC’s unprecedented energy.   One arm of a TOTEM T2 detector during its installation at interaction point 5. A composite particle like the proton is a complex system that in no way resembles a static Lego construction: sub-components move inside and interactions keep the whole thing together, but in a very dynamic way. This partly explains why even the very common proton can still be hiding secrets about its nature, decades after its discovery. One way of studying the inner properties of protons is to observe how they interact with each other, which, in technical terms, i...

  17. Small angle neutron scattering measurements of magnetic cluster sizes in magnetic recorging disks

    CERN Document Server

    Toney, M

    2003-01-01

    We describe Small Angle Neutron Scattering measurements of the magnetic cluster size distributions for several longitudinal magnetic recording media. We find that the average magnetic cluster size is slightly larger than the average physical grain size, that there is a broad distribution of cluster sizes, and that the cluster size is inversely correlated to the media signal-to-noise ratio. These results show that intergranular magnetic coupling in these media is small and they provide empirical data for the cluster-size distribution that can be incorporated into models of magnetic recording.

  18. Breast tumor size assessment: comparison of conventional ultrasound and contrast-enhanced ultrasound.

    Science.gov (United States)

    Jiang, Yu-Xin; Liu, He; Liu, Ji-Bin; Zhu, Qing-Li; Sun, Qiang; Chang, Xiao-Yan

    2007-12-01

    Accurate assessment of tumor size is necessary when selecting patients for breast-conserving surgery. In the study of breast contrast-enhanced ultrasound (CEUS), we found that tumor size discrepancy between CEUS and conventional ultrasound (US) existed in some breast lesions, for which the reasons are not clear. Breast CEUS examinations were performed in 104 patients with breast lesions. The measurement of the 104 breast tumors on conventional US was obtained and compared with the measurement on CEUS. A difference in measuring tumor size of >3 mm for tumors up to 1.7 cm and 4 mm for tumors >or=1.7 cm, was defined as a significant discrepancy between conventional US and CEUS. The histopathological examination of size discrepancy was performed and the margin characteristics of breast cancers with larger measurements were compared with those with unchanged measurements. Among the 104 lesions (43 malignant, 60 benign, 1 borderline), the size of 27 breast cancers and one granulomatous mastitis appeared larger at CEUS. Pathologic examinations of the region corresponding to the measurement discrepancy were mainly ductal carcinomas in situ (DCIS), invasive carcinoma with a DCIS component, adenosis with lobular hyperplasia in breast cancers and inflammatory cell infiltration in one granulomatous mastitis. Well-defined margin characteristics were significantly different between breast cancers with larger measurements at CEUS and those with unchanged measurements of size (p = 0.002), whereas no significant difference was found between the two groups in ill-defined, spiculated, hyperechoic halo, microlobulated and angulated margins (p = 0.463, 0.117, 0.194, 0.666 and 0.780, respectively). This initial study suggests that significant discrepancy of breast lesion measurement between conventional US and CEUS is more likely presented in breast cancer than benign lesions. The pathologic findings corresponding to the region of size increased at CEUS are malignant in most malignant

  19. Size-Dependent Regulation of Intracellular Trafficking of Polystyrene Nanoparticle-Based Drug-Delivery Systems.

    Science.gov (United States)

    Wang, Ting; Wang, Lu; Li, Xiaoming; Hu, Xingjie; Han, Yuping; Luo, Yao; Wang, Zejun; Li, Qian; Aldalbahi, Ali; Wang, Lihua; Song, Shiping; Fan, Chunhai; Zhao, Yun; Wang, Maolin; Chen, Nan

    2017-06-07

    Nanoparticles (NPs) have shown great promise as intracellular imaging probes or nanocarriers and are increasingly being used in biomedical applications. A detailed understanding of how NPs get "in and out" of cells is important for developing new nanomaterials with improved selectivity and less cytotoxicity. Both physical and chemical characteristics have been proven to regulate the cellular uptake of NPs. However, the exocytosis process and its regulation are less explored. Herein, we investigated the size-regulated endocytosis and exocytosis of carboxylated polystyrene (PS) NPs. PS NPs with a smaller size were endocytosed mainly through the clathrin-dependent pathway, whereas PS NPs with a larger size preferred caveolae-mediated endocytosis. Furthermore, our results revealed exocytosis of larger PS NPs and tracked the dynamic process at the single-particle level. These results indicate that particle size is a key factor for the regulation of intracellular trafficking of NPs and provide new insight into the development of more effective cellular nanocarriers.

  20. Women's Preferences for Penis Size: A New Research Method Using Selection among 3D Models.

    Science.gov (United States)

    Prause, Nicole; Park, Jaymie; Leung, Shannon; Miller, Geoffrey

    2015-01-01

    Women's preferences for penis size may affect men's comfort with their own bodies and may have implications for sexual health. Studies of women's penis size preferences typically have relied on their abstract ratings or selecting amongst 2D, flaccid images. This study used haptic stimuli to allow assessment of women's size recall accuracy for the first time, as well as examine their preferences for erect penis sizes in different relationship contexts. Women (N = 75) selected amongst 33, 3D models. Women recalled model size accurately using this method, although they made more errors with respect to penis length than circumference. Women preferred a penis of slightly larger circumference and length for one-time (length = 6.4 inches/16.3 cm, circumference = 5.0 inches/12.7 cm) versus long-term (length = 6.3 inches/16.0 cm, circumference = 4.8 inches/12.2 cm) sexual partners. These first estimates of erect penis size preferences using 3D models suggest women accurately recall size and prefer penises only slightly larger than average.

  1. Women's Preferences for Penis Size: A New Research Method Using Selection among 3D Models.

    Directory of Open Access Journals (Sweden)

    Nicole Prause

    Full Text Available Women's preferences for penis size may affect men's comfort with their own bodies and may have implications for sexual health. Studies of women's penis size preferences typically have relied on their abstract ratings or selecting amongst 2D, flaccid images. This study used haptic stimuli to allow assessment of women's size recall accuracy for the first time, as well as examine their preferences for erect penis sizes in different relationship contexts. Women (N = 75 selected amongst 33, 3D models. Women recalled model size accurately using this method, although they made more errors with respect to penis length than circumference. Women preferred a penis of slightly larger circumference and length for one-time (length = 6.4 inches/16.3 cm, circumference = 5.0 inches/12.7 cm versus long-term (length = 6.3 inches/16.0 cm, circumference = 4.8 inches/12.2 cm sexual partners. These first estimates of erect penis size preferences using 3D models suggest women accurately recall size and prefer penises only slightly larger than average.

  2. System-size corrections for self-diffusion coefficients calculated from molecular dynamics simulations: The case of CO{sub 2}, n-alkanes, and poly(ethylene glycol) dimethyl ethers

    Energy Technology Data Exchange (ETDEWEB)

    Moultos, Othonas A.; Economou, Ioannis G. [Chemical Engineering Program, Texas A& M University at Qatar, P.O. Box 23847, Doha (Qatar); Zhang, Yong; Maginn, Edward J., E-mail: ed@nd.edu [Department of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Tsimpanogiannis, Ioannis N. [Chemical Engineering Program, Texas A& M University at Qatar, P.O. Box 23847, Doha (Qatar); Environmental Research Laboratory, National Center for Scientific Research “Demokritos,” 15310 Aghia Paraskevi Attikis (Greece)

    2016-08-21

    Molecular dynamics simulations were carried out to study the self-diffusion coefficients of CO{sub 2}, methane, propane, n-hexane, n-hexadecane, and various poly(ethylene glycol) dimethyl ethers (glymes in short, CH{sub 3}O–(CH{sub 2}CH{sub 2}O){sub n}–CH{sub 3} with n = 1, 2, 3, and 4, labeled as G1, G2, G3, and G4, respectively) at different conditions. Various system sizes were examined. The widely used Yeh and Hummer [J. Phys. Chem. B 108, 15873 (2004)] correction for the prediction of diffusion coefficient at the thermodynamic limit was applied and shown to be accurate in all cases compared to extrapolated values at infinite system size. The magnitude of correction, in all cases examined, is significant, with the smallest systems examined giving for some cases a self-diffusion coefficient approximately 15% lower than the infinite system-size extrapolated value. The results suggest that finite size corrections to computed self-diffusivities must be used in order to obtain accurate results.

  3. Accelerating Smaller Cutbacks to Delay Larger Ones?

    DEFF Research Database (Denmark)

    Tepe, Markus; Vanhuysse, Pieter

    2012-01-01

    . Investigating both medium and large cutbacks in ageing welfare states, we test whether, in addition to conventional demographic and economic variables, political-institutional variables capturing partisanship (political ideology), electioneering (political cycle), and institutional constraints (political...... effects of unemployment and population aging: these socio-demographic variables tend to delay large-size cutbacks, but to accelerate medium-size cutbacks in pension generosity, possibly because they function as alarm bell signals urging policymakers to take still feasible incremental action through...

  4. Glomerular sieving of high molecular weight proteins in proteinuric rats

    International Nuclear Information System (INIS)

    Bertolatus, J.A.; Abuyousef, M.; Hunsicker, L.G.

    1987-01-01

    To characterize the permeability of the glomerular capillary wall to high molecular weight proteins in normal and proteinuric rats, we determined the glomerular sieving coefficients (GSC) of radioiodinated marker proteins of known size and charge by means of a paired label, tissue accumulation method previously validated in this laboratory. In one group of rats (Series A) the GSCs of 125 I-anionic IgG (aIgG-molecular weight [mol wt] 150,000, pI 4.9) and 131 I-neutral IgG (nIgG-pI 7.4 to 7.6) were measured simultaneously. In Series B, the GSC of a second anionic marker, 131 I-human ceruloplasmin (Crp-mol wt 137,000, pI 4.9) was compared to that of 125 I-nIgG. As in the previous report, the labeled proteins were not degraded or deiodinated during the 20 minute clearance period for GSC determination. Within Series A and B, three subgroups of rats were studied: control saline-infused rats, rats made acutely proteinuric by infusion of the polycation hexadimethrine (HDM), and rats with chronic doxorubicin (Adriamycin-Adria) nephrosis. In the control rats, GSCs for the anionic markers aIgG (Series A) or Crp (Series B) were significantly greater than that of nIgG (both series). These large proteins crossed the filtration barrier by a different pathway from that available to smaller neutral molecules the size of albumin, which in our previous study had a much higher GSC than a native, anionic albumin marker. In a third group of control rats only (Series C), the GSCs of native anionic bovine albumin (BSA) and nIgG were compared directly. The GSC of BSA (0.0029) was only slightly larger than the GSC of nIgG (0.0025), indicating that most of the native albumin crosses the glomerular capillary wall via a nonselective pathway similar to that available to nIgG. The results in the control groups are compatible with recently-described heteroporous models of glomerular size selectivity

  5. A Longitudinal Analysis of Search Engine Index Size

    DEFF Research Database (Denmark)

    Van den Bosch, Antal; Bogers, Toine; De Kunder, Maurice

    2015-01-01

    One of the determining factors of the quality of Web search engines is the size of their index. In addition to its influence on search result quality, the size of the indexed Web can also tell us something about which parts of the WWW are directly accessible to the everyday user. We propose a novel...... method of estimating the size of a Web search engine’s index by extrapolating from document frequencies of words observed in a large static corpus of Web pages. In addition, we provide a unique longitudinal perspective on the size of Google and Bing’s indexes over a nine-year period, from March 2006...... until January 2015. We find that index size estimates of these two search engines tend to vary dramatically over time, with Google generally possessing a larger index than Bing. This result raises doubts about the reliability of previous one-off estimates of the size of the indexed Web. We find...

  6. Evolution of students’ friendship networks: Examining the influence of group size

    Directory of Open Access Journals (Sweden)

    Valentina Sokolovska

    2017-01-01

    Full Text Available  The main aim of this study was to examine the effect of the network size on formation and evolution of students’ friendship relations. Data was collected from two groups of sociology freshmen: a group from the University of Belgrade, which represents a larger group, and a group from the University of Novi Sad, which represents a smaller group. The data was collected in three periods of one academic year. We analyzed the structural features of students’ networks and constructed a stochastic model of network evolution in order to explore how friendships form and change during one year. The results showed that structural features of the larger and the smaller group differ in each stage of friendship formation. At the beginning of group forming, small world structure was noticeable in the larger group, although full small world structure was not confirmed in both groups. Furthermore, transitivity of triads had effect on the evolution of the larger network, while balance or structural equivalence had effect on the evolution of the smaller network. Results of the structural analysis are in line with findings of the network evolution model and together they provide an insight into how friendship evolves in groups of different sizes.

  7. Portion sizes and obesity: responses of fast-food companies.

    Science.gov (United States)

    Young, Lisa R; Nestle, Marion

    2007-07-01

    Because the sizes of food portions, especially of fast food, have increased in parallel with rising rates of overweight, health authorities have called on fast-food chains to decrease the sizes of menu items. From 2002 to 2006, we examined responses of fast-food chains to such calls by determining the current sizes of sodas, French fries, and hamburgers at three leading chains and comparing them to sizes observed in 1998 and 2002. Although McDonald's recently phased out its largest offerings, current items are similar to 1998 sizes and greatly exceed those offered when the company opened in 1955. Burger King and Wendy's have increased portion sizes, even while health authorities are calling for portion size reductions. Fast-food portions in the United States are larger than in Europe. These observations suggest that voluntary efforts by fast-food companies to reduce portion sizes are unlikely to be effective, and that policy approaches are needed to reduce energy intake from fast food.

  8. Grain Size of Recall Practice for Lengthy Text Material: Fragile and Mysterious Effects on Memory

    Science.gov (United States)

    Wissman, Kathryn T.; Rawson, Katherine A.

    2015-01-01

    The current research evaluated the extent to which the grain size of recall practice for lengthy text material affects recall during practice and subsequent memory. The "grain size hypothesis" states that a smaller vs. larger grain size will increase retrieval success during practice that in turn will enhance subsequent memory for…

  9. Size effect in tension perpendicular to the grain

    DEFF Research Database (Denmark)

    Pedersen, Martin Bo Uhre; Clorius, Christian Odin; Damkilde, Lars

    1999-01-01

    The strength in tension perpendicular to the grain is known to decrease with an increase in the stressed volume. Usually this size effect is explained on a stochastic basis, that is an explanation relying on an increased probability of encountering a strength reducing flaw when the volume...... of the material under stress is increased. This paper presents a small experimental investigation on specimens with well defined structural orientation of the material. The experiments exhibit a larger size effect than expected and furthermore the data and the nature of the failures encountered suggest...... that the size effect can be explained on a deterministic basis. Arguments for such a simple deterministic explanation of size effect is found in finite element modelling using the orthotropic stiffness characteristics in the transverse plane of wood....

  10. Molecular control of brain size: Regulators of neural stem cell life, death and beyond

    International Nuclear Information System (INIS)

    Joseph, Bertrand; Hermanson, Ola

    2010-01-01

    The proper development of the brain and other organs depends on multiple parameters, including strictly controlled expansion of specific progenitor pools. The regulation of such expansion events includes enzymatic activities that govern the correct number of specific cells to be generated via an orchestrated control of cell proliferation, cell cycle exit, differentiation, cell death etc. Certain proteins in turn exert direct control of these enzymatic activities and thus progenitor pool expansion and organ size. The members of the Cip/Kip family (p21Cip1/p27Kip1/p57Kip2) are well-known regulators of cell cycle exit that interact with and inhibit the activity of cyclin-CDK complexes, whereas members of the p53/p63/p73 family are traditionally associated with regulation of cell death. It has however become clear that the roles for these proteins are not as clear-cut as initially thought. In this review, we discuss the roles for proteins of the Cip/Kip and p53/p63/p73 families in the regulation of cell cycle control, differentiation, and death of neural stem cells. We suggest that these proteins act as molecular interfaces, or 'pilots', to assure the correct assembly of protein complexes with enzymatic activities at the right place at the right time, thereby regulating essential decisions in multiple cellular events.

  11. Molecular control of brain size: Regulators of neural stem cell life, death and beyond

    Energy Technology Data Exchange (ETDEWEB)

    Joseph, Bertrand [Department of Oncology-Pathology, Cancer Centrum Karolinska (CCK), Karolinska Institutet, Stockholm (Sweden); Hermanson, Ola, E-mail: ola.hermanson@ki.se [Linnaeus Center in Developmental Biology for Regenerative Medicine (DBRM), Department of Neuroscience, Karolinska Institutet, Stockholm (Sweden)

    2010-05-01

    The proper development of the brain and other organs depends on multiple parameters, including strictly controlled expansion of specific progenitor pools. The regulation of such expansion events includes enzymatic activities that govern the correct number of specific cells to be generated via an orchestrated control of cell proliferation, cell cycle exit, differentiation, cell death etc. Certain proteins in turn exert direct control of these enzymatic activities and thus progenitor pool expansion and organ size. The members of the Cip/Kip family (p21Cip1/p27Kip1/p57Kip2) are well-known regulators of cell cycle exit that interact with and inhibit the activity of cyclin-CDK complexes, whereas members of the p53/p63/p73 family are traditionally associated with regulation of cell death. It has however become clear that the roles for these proteins are not as clear-cut as initially thought. In this review, we discuss the roles for proteins of the Cip/Kip and p53/p63/p73 families in the regulation of cell cycle control, differentiation, and death of neural stem cells. We suggest that these proteins act as molecular interfaces, or 'pilots', to assure the correct assembly of protein complexes with enzymatic activities at the right place at the right time, thereby regulating essential decisions in multiple cellular events.

  12. Effects of crystal size on the mechanical properties of a lithium disilicate glass-ceramic

    Energy Technology Data Exchange (ETDEWEB)

    Li, D. [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, 28 West Xianning Road, Xi’an 710049 (China); Guo, J.W.; Wang, X.S; Zhang, S.F. [State Key Laboratory of Military Stomatology, Department of Prosthodontics, School of Stomatology, Fourth Military Medical University, 145 West Changle Road, Xi’an 710032 (China); He, L., E-mail: helin@mail.xjtu.edu.cn [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, 28 West Xianning Road, Xi’an 710049 (China)

    2016-07-04

    Crystal size of lithium disilicate (LD) phase in a LD glass-ceramic was changed by thermally controlled crystallization of a precursory LD glass at different temperatures. Effects of the crystal size on the mechanical properties of the glass-ceramic were investigated. It was found that the flexural strength presented a hump-like variation trend with increasing the crystal size, the hardness monotonously decreased at the same time. It was further confirmed that micro residual compressive stresses existed inside the LD crystals due to the thermal expansion mismatch between the glass matrix and the crystalline phase. The levels of the residual stresses increased with increasing the crystal size. The crystal size performed dual effects on the flexural strength of the glass-ceramic: an “interlocking effect” caused by larger-sized LD crystals and a “micro residual stress effect” related to the balancing tensile stresses in the glass matrix. Higher residual tensile stresses in the glass matrix induced by larger-sized LD crystals would counteract the “interlocking effect” of the crystals, causing the strength degradation. The hardness of the glass-ceramic was mainly controlled by the “micro residual stress effect”.

  13. Size scaling of static friction.

    Science.gov (United States)

    Braun, O M; Manini, Nicola; Tosatti, Erio

    2013-02-22

    Sliding friction across a thin soft lubricant film typically occurs by stick slip, the lubricant fully solidifying at stick, yielding and flowing at slip. The static friction force per unit area preceding slip is known from molecular dynamics (MD) simulations to decrease with increasing contact area. That makes the large-size fate of stick slip unclear and unknown; its possible vanishing is important as it would herald smooth sliding with a dramatic drop of kinetic friction at large size. Here we formulate a scaling law of the static friction force, which for a soft lubricant is predicted to decrease as f(m)+Δf/A(γ) for increasing contact area A, with γ>0. Our main finding is that the value of f(m), controlling the survival of stick slip at large size, can be evaluated by simulations of comparably small size. MD simulations of soft lubricant sliding are presented, which verify this theory.

  14. Congregational Size and Attitudes towards Racial Inequality among Church Attendees in America

    Directory of Open Access Journals (Sweden)

    Ryon J. Cobb

    2015-06-01

    Full Text Available Research suggests that congregational characteristics are associated with the racial attitudes of American churchgoers. This study examines the relationship between congregational size and beliefs about the Black/White socioeconomic gap among religious adherents. Method. Drawing upon data from the General Social Survey and the National Congregations Study, we fit binary logistic regression models to estimate the association between congregational size and Americans’ explanations of Black/White economic inequality. Results. Findings reveal that attendees of larger congregations are less likely than attendees of smaller congregations to explain racial inequality as the result of the racial discrimination. The likelihood of explaining racial inequality in terms of personal motivation does not vary by congregation size. Conclusion. Despite the growing diversity in larger congregations in America, such congregations may steer attendees’ views about racial inequality away from systemic/structural factors, which may attenuate the ability of such congregations to bridge racial divisions.

  15. Facile Synthesis of Micron-Sized Hollow Silver Spheres as Substrates for Surface-Enhanced Raman Scattering

    Directory of Open Access Journals (Sweden)

    Lixin Xia

    2014-01-01

    Full Text Available A well-designed type of micron-sized hollow silver sphere was successfully synthesized by a simple hard-template method to be used as substrates for surface-enhanced Raman scattering. 4 Å molecular sieves were employed as a removable solid template. [Ag(NH32]+ was absorbed as the precursor on the surface of the molecular sieve. Formaldehyde was selected as a reducing agent to reduce [Ag(NH32]+, resulting in the formation of a micron-sized silver shell on the surface of the 4 Å molecular sieves. The micron-sized hollow silver spheres were obtained by removing the molecular sieve template. SEM and XRD were used to characterize the structure of the micron-sized hollow silver spheres. The as-prepared micro-silver spheres exhibited robust SERS activity in the presence of adsorbed 4-mercaptobenzoic acid (4-MBA with excitation at 632.8 nm, and the enhancement factor reached ~1.5 × 106. This synthetic process represents a promising method for preparing various hollow metal nanoparticles.

  16. Self-assembled isoporous block copolymer membranes with tuned pore sizes.

    Science.gov (United States)

    Yu, Haizhou; Qiu, Xiaoyan; Nunes, Suzana P; Peinemann, Klaus-Viktor

    2014-09-15

    The combination of nonsolvent-induced phase separation and the self-assembly of block copolymers can lead to asymmetric membranes with a thin highly ordered isoporous skin layer. The effective pore size of such membranes is usually larger than 15 nm. We reduced the pore size of these membranes by electroless gold deposition. We demonstrate that the pore sizes can be controlled precisely between 3 and 20 nm leading to a tunable sharp size discrimination in filtration processes. Besides fractionation of nanoparticles and biomaterials, controlled drug delivery is an attractive potential application. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Gas Sensors Based on Molecular Imprinting Technology

    OpenAIRE

    Zhang, Yumin; Zhang, Jin; Liu, Qingju

    2017-01-01

    Molecular imprinting technology (MIT); often described as a method of designing a material to remember a target molecular structure (template); is a technique for the creation of molecularly imprinted polymers (MIPs) with custom-made binding sites complementary to the target molecules in shape; size and functional groups. MIT has been successfully applied to analyze; separate and detect macromolecular organic compounds. Furthermore; it has been increasingly applied in assays of biological mac...

  18. Fine-grained versus categorical: Pupil size differentiates between strategies for spatial working memory performance.

    Science.gov (United States)

    Starc, Martina; Anticevic, Alan; Repovš, Grega

    2017-05-01

    Pupillometry provides an accessible option to track working memory processes with high temporal resolution. Several studies showed that pupil size increases with the number of items held in working memory; however, no study has explored whether pupil size also reflects the quality of working memory representations. To address this question, we used a spatial working memory task to investigate the relationship of pupil size with spatial precision of responses and indicators of reliance on generalized spatial categories. We asked 30 participants (15 female, aged 19-31) to remember the position of targets presented at various locations along a hidden radial grid. After a delay, participants indicated the remembered location with a high-precision joystick providing a parametric measure of trial-to-trial accuracy. We recorded participants' pupil dilations continuously during task performance. Results showed a significant relation between pupil dilation during preparation/early encoding and the precision of responses, possibly reflecting the attentional resources devoted to memory encoding. In contrast, pupil dilation at late maintenance and response predicted larger shifts of responses toward prototypical locations, possibly reflecting larger reliance on categorical representation. On an intraindividual level, smaller pupil dilations during encoding predicted larger dilations during late maintenance and response. On an interindividual level, participants relying more on categorical representation also produced larger precision errors. The results confirm the link between pupil size and the quality of spatial working memory representation. They suggest compensatory strategies of spatial working memory performance-loss of precise spatial representation likely increases reliance on generalized spatial categories. © 2017 Society for Psychophysiological Research.

  19. The effect of low molecular weight multifunctional additives on heavy oil viscosity

    Energy Technology Data Exchange (ETDEWEB)

    Oldenburg, T.B.P.; Yarranton, H.W.; Larter, S.R. [Calgary Univ., AB (Canada)

    2010-07-01

    Crude oils contain many small multifunctional low molecular weight components that act as linking molecules between larger functionalized species. The linkage molecules have a significant impact on the flow properties of hydrocarbon systems. This study investigated the use of a low molecular weight multiheteroatom species (LMWMH) as a molecular Velcro linking high molecular weight components together. LMWMH species were added to Albertan bitumens and heavy oil, and their impact on viscosity was investigated. Results of the experimental studies were then compared with the effects of hydrocarbon solvents on similar samples. The LMWMH species included bifunctional species and analogous alkyl and aryl monoamines that acted as blocking molecules to hinder the association of larger petroleum species. Density and viscosity measurements were conducted. A correlation method was used to predict the viscosity of the solvent-diluted heavy oil and bitumen samples. The study showed that of the tested additives, only aniline demonstrated an additional viscosity-reducing effect. The aniline inhibited asphaltene association and is a promising candidate for enhanced in-situ bitumen viscosity reduction. 23 refs., 4 tabs.

  20. Font Size Matters—Emotion and Attention in Cortical Responses to Written Words

    OpenAIRE

    Bayer, Mareike; Sommer, Werner; Schacht, Annekathrin

    2012-01-01

    For emotional pictures with fear-, disgust-, or sex-related contents, stimulus size has been shown to increase emotion effects in attention-related event-related potentials (ERPs), presumably reflecting the enhanced biological impact of larger emotion-inducing pictures. If this is true, size should not enhance emotion effects for written words with symbolic and acquired meaning. Here, we investigated ERP effects of font size for emotional and neutral words. While P1 and N1 amplitu...

  1. Unravelling anisogamy: egg size and ejaculate size mediate selection on morphology in free-swimming sperm.

    Science.gov (United States)

    Monro, Keyne; Marshall, Dustin J

    2016-07-13

    Gamete dimorphism (anisogamy) defines the sexes in most multicellular organisms. Theoretical explanations for its maintenance usually emphasize the size-related selection pressures of sperm competition and zygote survival, assuming that fertilization of all eggs precludes selection for phenotypes that enhance fertility. In external fertilizers, however, fertilization is often incomplete due to sperm limitation, and the risk of polyspermy weakens the advantage of high sperm numbers that is predicted to limit sperm size, allowing alternative selection pressures to target free-swimming sperm. We asked whether egg size and ejaculate size mediate selection on the free-swimming sperm of Galeolaria caespitosa, a marine tubeworm with external fertilization, by comparing relationships between sperm morphology and male fertility across manipulations of egg size and sperm density. Our results suggest that selection pressures exerted by these factors may aid the maintenance of anisogamy in external fertilizers by limiting the adaptive value of larger sperm in the absence of competition. In doing so, our study offers a more complete explanation for the stability of anisogamy across the range of sperm environments typical of this mating system and identifies new potential for the sexes to coevolve via mutual selection pressures exerted by gametes at fertilization. © 2016 The Author(s).

  2. Using ethane and butane as probes to the molecular structure of 1-alkyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl] imide ionic liquids.

    Science.gov (United States)

    Costa Gomes, Margarida F; Pison, Laure; Pensado, Alfonso S; Pádua, Agilio A H

    2012-01-01

    In this work, we have studied the solubility and the thermodynamic properties of solvation, between 298 and 343 K and at pressures close to atmospheric, of ethane and n-butane in several ionic liquids based on the bis[(trifluoromethyl) sulfonyl]imide anion and on 1-alkyl-3-methylimidazolium cations, [CnC1Im] [NTf2], with alkyl side-chains varying from two to ten carbon atoms. The solubility of butane is circa one order of magnitude larger than that of ethane with mole fractions as high as 0.15 in [C10C1Im][NTf2] at 300 K. The solubilities of both n-butane and ethane gases are higher for ionic liquids with longer alkyl chains. The behaviour encountered is explained by the preferential solvation of the gases in the non-polar domains of the solvents, the larger solubility of n-butane being attributed to the dispersive contributions to the interaction energy. The rise in solubility with increasing size of the alkyl-side chain is explained by a more favourable entropy of solvation in the ionic liquids with larger cations. These conclusions are corroborated by molecular dynamics simulation studies.

  3. Impact of implant size on cement filling in hip resurfacing arthroplasty.

    Science.gov (United States)

    de Haan, Roel; Buls, Nico; Scheerlinck, Thierry

    2014-01-01

    Larger proportions of cement within femoral resurfacing implants might result in thermal bone necrosis. We postulate that smaller components are filled with proportionally more cement, causing an elevated failure rate. A total of 19 femoral heads were fitted with polymeric replicas of ReCap (Biomet) resurfacing components fixed with low-viscosity cement. Two specimens were used for each even size between 40 and 56 mm and one for size 58 mm. All specimens were imaged with computed tomography, and the cement thickness and bone density were analyzed. The average cement mantle thickness was 2.63 mm and was not correlated with the implant size. However, specimen with low bone density had thicker cement mantles regardless of size. The average filling index was 36.65% and was correlated to both implant size and bone density. Smaller implants and specimens with lower bone density contained proportionally more cement than larger implants. According to a linear regression model, bone density but not implant size influenced cement thickness. However, both implant size and bone density had a significant impact on the filling index. Large proportions of cement within the resurfacing head have the potential to generate thermal bone necrosis and implant failure. When considering hip resurfacing in patients with a small femoral head and/or osteoporotic bone, extra care should be taken to avoid thermal bone necrosis, and alternative cementing techniques or even cementless implants should be considered. This study should help delimiting the indications for hip resurfacing and to choose an optimal cementing technique taking implant size into account.

  4. Specific Noncovalent Association of Chiral Large-Ring Hexaimines: Ion Mobility Mass Spectrometry and PM7 Study.

    Science.gov (United States)

    Troć, Anna; Gajewy, Jadwiga; Danikiewicz, Witold; Kwit, Marcin

    2016-09-05

    Ion mobility mass spectrometry and PM7 semiempirical calculations are effective complementary methods to study gas phase formation of noncovalent complexes from vaselike macrocycles. The specific association of large-ring chiral hexaimines, derived from enantiomerically pure trans-1,2-diaminocyclohexane and various isophthaldehydes, is driven mostly by CH-π and π-π stacking interactions. The isotrianglimine macrocycles are prone to form two types of aggregates: tail-to-tail and head-to-head (capsule) dimers. The stability of the tail-to-tail dimers is affected by the size and electronic properties of the substituents at the C-5 position of the aromatic ring. Electron-withdrawing groups stabilize the aggregate, whereas bulky or electron-donating groups destabilize the complexes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Information overload or search-amplified risk? Set size and order effects on decisions from experience.

    Science.gov (United States)

    Hills, Thomas T; Noguchi, Takao; Gibbert, Michael

    2013-10-01

    How do changes in choice-set size influence information search and subsequent decisions? Moreover, does information overload influence information processing with larger choice sets? We investigated these questions by letting people freely explore sets of gambles before choosing one of them, with the choice sets either increasing or decreasing in number for each participant (from two to 32 gambles). Set size influenced information search, with participants taking more samples overall, but sampling a smaller proportion of gambles and taking fewer samples per gamble, when set sizes were larger. The order of choice sets also influenced search, with participants sampling from more gambles and taking more samples overall if they started with smaller as opposed to larger choice sets. Inconsistent with information overload, information processing appeared consistent across set sizes and choice order conditions, reliably favoring gambles with higher sample means. Despite the lack of evidence for information overload, changes in information search did lead to systematic changes in choice: People who started with smaller choice sets were more likely to choose gambles with the highest expected values, but only for small set sizes. For large set sizes, the increase in total samples increased the likelihood of encountering rare events at the same time that the reduction in samples per gamble amplified the effect of these rare events when they occurred-what we call search-amplified risk. This led to riskier choices for individuals whose choices most closely followed the sample mean.

  6. Rapid Increase in Genome Size as a Consequence of Transposable Element Hyperactivity in Wood-White (Leptidea) Butterflies.

    Science.gov (United States)

    Talla, Venkat; Suh, Alexander; Kalsoom, Faheema; Dinca, Vlad; Vila, Roger; Friberg, Magne; Wiklund, Christer; Backström, Niclas

    2017-10-01

    Characterizing and quantifying genome size variation among organisms and understanding if genome size evolves as a consequence of adaptive or stochastic processes have been long-standing goals in evolutionary biology. Here, we investigate genome size variation and association with transposable elements (TEs) across lepidopteran lineages using a novel genome assembly of the common wood-white (Leptidea sinapis) and population re-sequencing data from both L. sinapis and the closely related L. reali and L. juvernica together with 12 previously available lepidopteran genome assemblies. A phylogenetic analysis confirms established relationships among species, but identifies previously unknown intraspecific structure within Leptidea lineages. The genome assembly of L. sinapis is one of the largest of any lepidopteran taxon so far (643 Mb) and genome size is correlated with abundance of TEs, both in Lepidoptera in general and within Leptidea where L. juvernica from Kazakhstan has considerably larger genome size than any other Leptidea population. Specific TE subclasses have been active in different Lepidoptera lineages with a pronounced expansion of predominantly LINEs, DNA elements, and unclassified TEs in the Leptidea lineage after the split from other Pieridae. The rate of genome expansion in Leptidea in general has been in the range of four Mb/Million year (My), with an increase in a particular L. juvernica population to 72 Mb/My. The considerable differences in accumulation rates of specific TE classes in different lineages indicate that TE activity plays a major role in genome size evolution in butterflies and moths. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  7. Listing of nuclear power plant larger than 100 MWe

    International Nuclear Information System (INIS)

    McHugh, B.

    1976-03-01

    This report contains a list of all nuclear power plants larger than 100 MWe, printed out from the Argus Data Bank at Chalmers University of Technology in Sweden. The plants are listed by NSSS supply. (M.S.)

  8. Synthesis of nanometer-size inorganic materials for the examination of particle size effects on heterogeneous catalysis

    Science.gov (United States)

    Emerson, Sean Christian

    The effect of acoustic and hydrodynamic cavitation on the precipitation of inorganic catalytic materials, specifically titania supported gold, was investigated. The overall objective was to understand the fundamental factors involved in synthesizing nanometer-size catalytic materials in the 1--10 nm range in a cavitating field. Materials with grain sizes in this range have been associated with enhanced catalytic activity compared to larger grain size materials. A new chemical approach was used to produce titania supported gold by co-precipitation with higher gold yields compared to other synthesis methods. Using this approach, it was determined that acoustic cavitation was unable to influence the gold mean crystallite size compared to non-sonicated catalysts. However, gold concentration on the catalysts was found to be very important for CO oxidation activity. By decreasing the gold concentration from a weight loading of 0.50% down to approximately 0.05%, the rate of reaction per mole of gold was found to increase by a factor of 19. Hydrodynamic cavitation at low pressures (6.9--48 bar) was determined to have no effect on gold crystallite size at a fixed gold content for the same precipitation technique used in the acoustic cavitation studies. By changing the chemistry of the precipitation system, however, it was found that a synergy existed between the dilution of the gold precursor solution, the orifice diameter, and the reducing agent addition rate. Individually, these factors were found to have little effect and only their interaction allowed gold grain size control in the range of 8--80 nm. Further modification of the system chemistry and the use of hydrodynamic cavitation at pressures in excess of 690 bar allowed the systematic control of gold crystallite size in the range of 2--9 nm for catalysts containing 2.27 +/- 0.17% gold. In addition, it was shown that the enhanced mixing due to cavitation led to larger gold yields compared to classical syntheses. The

  9. The Effect of Size and Ecology on Extinction Susceptibility

    Science.gov (United States)

    Huynh, C.; Yuan, A.; Heim, N.; Payne, J.

    2015-12-01

    Although life on Earth first emerged as prokaryotic organisms, it eventually evolved into billions of different species. However, extinctions on Earth, especially the five mass extinctions, have decimated species. So what leads to a species survival or demise during a mass extinction? Are certain species more susceptible to extinctions based on their size and ecology? For this project, we focused on the data of marine animals. To examine the impact of size and ecology on a species's likelihood of survival, we compared the sizes and ecologies of the survivors and victims of the five mass extinctions. The ecology, or life mode, of a genus consists of the combination of tiering, motility, and feeding mechanism. Tiering refers to the animal's typical location in the water column and sediments, motility refers to its ability to move, and feeding mechanism describes the way the organism eats; together, they describe the animal's behavior. We analyzed the effect of ecology on survival using logistic regression, which compares life mode to the success or failure of a genus during each mass extinction interval. For organism size, we found the extinct organisms' mean size (both volume and length) and compared it with the average size of survivors on a graph. Our results show that while surviving genera of mass extinctions tended to be slightly larger than those that went extinct, there was no significant difference. Even though the Permian (Changhsingian) and Triassic (Rhaetian) extinctions had larger surviving species, likewise the difference was small. Ecology had a more obvious impact on the likelihood of survival; fast-moving, predatory pelagic organisms were the most likely to go extinct, while sedentary, infaunal suspension feeders had the greatest chances of survival. Overall, ecology played a greater role than size in determining the survival of a species. With this information, we can use ecology to predict which species would survive future extinctions.

  10. Particle size distribution of hydrocyanic acid in gari, a cassava-based product.

    Science.gov (United States)

    Maduagwu, E N; Fafunso, M

    1980-12-01

    A reciprocal relationship was observed between the cyanide content of gari and particle size. Hydrocyanic acid (HCN) content was positively correlated (r = 0.62) with sugar content but the correlation with starch content was poor (r = 0.33). From both the nutritional and toxicological standpoints, it would appear that larger particles size in gari is beneficial.

  11. Micro-drinking behaviours and consumption of wine in different wine glass sizes: a laboratory study.

    Science.gov (United States)

    Zupan, Z; Pechey, R; Couturier, D L; Hollands, G J; Marteau, T M

    2017-06-12

    Tableware size may influence how much food and non-alcoholic drink is consumed. Preliminary evidence of the impact of glass size on purchasing of alcoholic drinks shows an increase in wine sales of almost 10% when the same portion of wine is served in a larger glass. The primary aim of the current study is to test if micro-drinking behaviours act as a mechanism that could underlie this effect, through an increase in drinking rate, sip duration and/or number of sips from a larger glass. In a between-subjects experimental design, 166 young women were randomised to drink a 175 ml portion of wine from either a smaller (250 ml) or larger (370 ml) wine glass. Primary outcomes were three micro-drinking behaviours, assessed observationally using video recordings: drinking rate, sip number and sip duration. Other possible mechanisms examined were satisfaction with the perceived amount of wine served and pleasure of the drinking experience, assessed using self-report measures. Wine drunk from the larger, compared with the smaller glass, was consumed more slowly and with shorter sip duration, counter to the hypothesised direction of effect. No differences were observed in any of the other outcome measures. These findings provide no support for the hypothesised mechanisms by which serving wine in larger wine glasses increases consumption. While micro-drinking behaviours may still prove to be a mechanism explaining consumption from different glass sizes, cross-validation of these results in a more naturalistic setting is needed.

  12. High-yield fabrication and properties of 1.4 nm nanodiamonds with narrow size distribution.

    Science.gov (United States)

    Stehlik, Stepan; Varga, Marian; Ledinsky, Martin; Miliaieva, Daria; Kozak, Halyna; Skakalova, Viera; Mangler, Clemens; Pennycook, Timothy J; Meyer, Jannik C; Kromka, Alexander; Rezek, Bohuslav

    2016-12-02

    Detonation nanodiamonds (DNDs) with a typical size of 5 nm have attracted broad interest in science and technology. Further size reduction of DNDs would bring these nanoparticles to the molecular-size level and open new prospects for research and applications in various fields, ranging from quantum physics to biomedicine. Here we show a controllable size reduction of the DND mean size down to 1.4 nm without significant particle loss and with additional disintegration of DND core agglutinates by air annealing, leading to a significantly narrowed size distribution (±0.7 nm). This process is scalable to large quantities. Such molecular-sized DNDs keep their diamond structure and characteristic DND features as shown by Raman spectroscopy, infrared spectroscopy, STEM and EELS. The size of 1 nm is identified as a limit, below which the DNDs become amorphous.

  13. High-yield fabrication and properties of 1.4 nm nanodiamonds with narrow size distribution

    Science.gov (United States)

    Stehlik, Stepan; Varga, Marian; Ledinsky, Martin; Miliaieva, Daria; Kozak, Halyna; Skakalova, Viera; Mangler, Clemens; Pennycook, Timothy J.; Meyer, Jannik C.; Kromka, Alexander; Rezek, Bohuslav

    2016-12-01

    Detonation nanodiamonds (DNDs) with a typical size of 5 nm have attracted broad interest in science and technology. Further size reduction of DNDs would bring these nanoparticles to the molecular-size level and open new prospects for research and applications in various fields, ranging from quantum physics to biomedicine. Here we show a controllable size reduction of the DND mean size down to 1.4 nm without significant particle loss and with additional disintegration of DND core agglutinates by air annealing, leading to a significantly narrowed size distribution (±0.7 nm). This process is scalable to large quantities. Such molecular-sized DNDs keep their diamond structure and characteristic DND features as shown by Raman spectroscopy, infrared spectroscopy, STEM and EELS. The size of 1 nm is identified as a limit, below which the DNDs become amorphous.

  14. Immobilization thresholds of electrofishing relative to fish size

    Science.gov (United States)

    Dolan, C.R.; Miranda, L.E.

    2003-01-01

    Fish size and electrical waveforms have frequently been associated with variation in electrofishing effectiveness. Under controlled laboratory conditions, we measured the electrical power required by five electrical waveforms to immobilize eight fish species of diverse sizes and shapes. Fish size was indexed by total body length, surface area, volume, and weight; shape was indexed by the ratio of body length to body depth. Our objectives were to identify immobilization thresholds, elucidate the descriptors of fish size that were best associated with those immobilization thresholds, and determine whether the vulnerability of a species relative to other species remained constant across electrical treatments. The results confirmed that fish size is a key variable controlling the immobilization threshold and further suggested that the size descriptor best related to immobilization is fish volume. The peak power needed to immobilize fish decreased rapidly with increasing fish volume in small fish but decreased slowly for fish larger than 75-100 cm 3. Furthermore, when we controlled for size and shape, different waveforms did not favor particular species, possibly because of the overwhelming effect of body size. Many of the immobilization inconsistencies previously attributed to species might simply represent the effect of disparities in body size.

  15. Weber's Illusion and Body Shape: Anisotropy of Tactile Size Perception on the Hand

    Science.gov (United States)

    Longo, Matthew R.; Haggard, Patrick

    2011-01-01

    The perceived distance between touches on a single skin surface is larger on regions of high tactile sensitivity than those with lower acuity, an effect known as "Weber's illusion". This illusion suggests that tactile size perception involves a representation of the perceived size of body parts preserving characteristics of the somatosensory…

  16. The neural processing of musical instrument size information in the brain investigated by magnetoencephalography

    Science.gov (United States)

    Rupp, Andre; van Dinther, Ralph; Patterson, Roy D.

    2005-04-01

    The specific cortical representation of size was investigated by recording auditory evoked fields (AEFs) elicited by changes of instrument size and pitch. In Experiment 1, a French horn and one scaled to double the size played a three note melody around F3 or its octave, F4. Many copies of these four melodies were played in random order and the AEF was measured continuously. A similar procedure was applied to saxophone sounds in a separate run. In Experiment 2, the size and type of instrument (French horn and saxophone) were varied without changing the octave. AEFs were recorded in five subjects using magnetoencephalography and evaluated by spatio-temporal source analysis with one equivalent dipole in each hemisphere. The morphology of the source waveforms revealed that each note within the melody elicits a well-defined P1-N1-P2 AEF-complex with adaptation for the 2nd and 3rd note. At the transition of size, pitch, or both, a larger AEF-complex was evoked. However, size changes elicited a stronger N1 than pitch changes. Furthermore, this size-related N1 enhancement was larger for French horn than saxophone. The results indicate that the N1 plays an important role in the specific representation of instrument size.

  17. Body size distributions of the pale grass blue butterfly in Japan: Size rules and the status of the Fukushima population

    Science.gov (United States)

    Taira, Wataru; Iwasaki, Mayo; Otaki, Joji M.

    2015-01-01

    The body size of the pale grass blue butterfly, Zizeeria maha, has been used as an environmental indicator of radioactive pollution caused by the Fukushima nuclear accident. However, geographical and temporal size distributions in Japan and temperature effects on size have not been established in this species. Here, we examined the geographical, temporal, and temperature-dependent changes of the forewing size of Z. maha argia in Japan. Butterflies collected in 2012 and 2013 from multiple prefectures throughout Japan demonstrated an inverse relationship of latitude and forewing size, which is the reverse of Bergmann’s cline. The Fukushima population was significantly larger than the Aomori and Miyagi populations and exhibited no difference from most of the other prefectural populations. When monitored at a single geographic locality every other month, forewing sizes were the largest in April and the smallest in August. Rearing larvae at a constant temperature demonstrated that forewing size followed the temperature-size rule. Therefore, the converse Bergmann’s rule and the temperature-size rule coexist in this multivoltine species. Our study establishes this species as a useful environmental indicator and supports the idea that the size reduction observed only in Fukushima Prefecture in 2011 was caused by the environmental stress of radioactive pollution. PMID:26197998

  18. Top-spray fluid bed coating: Scale-up in terms of relative droplet size and drying force

    DEFF Research Database (Denmark)

    Hede, Peter Dybdahl; Bach, P.; Jensen, Anker Degn

    2008-01-01

    in terms of particle size fractions larger than 425 mu m determined by sieve analysis. Results indicated that the particle size distribution may be reproduced across scale with statistical valid precision by keeping the drying force and the relative droplet size constant across scale. It is also shown...

  19. Self-consistent field theory based molecular dynamics with linear system-size scaling

    Energy Technology Data Exchange (ETDEWEB)

    Richters, Dorothee [Institute of Mathematics and Center for Computational Sciences, Johannes Gutenberg University Mainz, Staudinger Weg 9, D-55128 Mainz (Germany); Kühne, Thomas D., E-mail: kuehne@uni-mainz.de [Institute of Physical Chemistry and Center for Computational Sciences, Johannes Gutenberg University Mainz, Staudinger Weg 7, D-55128 Mainz (Germany); Technical and Macromolecular Chemistry, University of Paderborn, Warburger Str. 100, D-33098 Paderborn (Germany)

    2014-04-07

    We present an improved field-theoretic approach to the grand-canonical potential suitable for linear scaling molecular dynamics simulations using forces from self-consistent electronic structure calculations. It is based on an exact decomposition of the grand canonical potential for independent fermions and does neither rely on the ability to localize the orbitals nor that the Hamilton operator is well-conditioned. Hence, this scheme enables highly accurate all-electron linear scaling calculations even for metallic systems. The inherent energy drift of Born-Oppenheimer molecular dynamics simulations, arising from an incomplete convergence of the self-consistent field cycle, is circumvented by means of a properly modified Langevin equation. The predictive power of the present approach is illustrated using the example of liquid methane under extreme conditions.

  20. Why borrowers pay premiums to larger lenders: Empirical evidence from sovereign syndicated loans

    OpenAIRE

    Hallak, Issam

    2002-01-01

    All other terms being equal (e.g. seniority), syndicated loan contracts provide larger lending compensations (in percentage points) to institutions funding larger amounts. This paper explores empirically the motivation for such a price design on a sample of sovereign syndicated loans in the period 1990-1997. I find strong evidence that a larger premium is associated with higher renegotiation probability and information asymmetries. It hardly has any impact on the number of lenders though. Thi...

  1. Beyond Panglossian Optimism: Larger N2 Amplitudes Probably Signal a Bilingual Disadvantage in Conflict Monitoring

    Directory of Open Access Journals (Sweden)

    Kenneth R. Paap

    2015-01-01

    Full Text Available In this special issue on the brain mechanisms that lead to cognitive benefits of bilingualism we discussed six reasons why it will be very difficult to discover those mechanisms. Many of these problems apply to the article by Fernandez, Acosta, Douglass, Doshi, and Tartar that also appears in the special issue. These concerns include the following: 1 an overly optimistic assessment of the replicability of bilingual advantages in behavioral studies, 2 reliance on risky small samples sizes, 3 failures to match the samples on demographic characteristics such as immigrant status, and 4 language group differences that occur in neural measures (i.e., N2 amplitude, but not in the behavioral data. Furthermore the N2 amplitude measure in general suffers from valence ambiguity: larger N2 amplitudes reported for bilinguals are more likely to reflect poorer conflict resolution rather than enhanced inhibitory control.

  2. The reported availability of general practitioners and the influence of practice list size.

    OpenAIRE

    Campbell, J L

    1996-01-01

    BACKGROUND: Combined practice list sizes have increased, but larger practice size may be associated with disadvantage to patients. AIM: The aim of the study was to investigate the availability of general practitioners as reported by their patients and the relationship between reported availability and practice list size. METHOD: A one-week questionnaire survey of 8315 patients attending participating practices in West Lothian, Scotland, was conducted. Patients were asked about the arrangement...

  3. Annual spatiotemporal migration schedules in three larger insectivorous birds

    DEFF Research Database (Denmark)

    Jacobsen, Lars Bo; Jensen, Niels Odder; Willemoes, Mikkel

    2017-01-01

    Background: Knowledge of spatiotemporal migration patterns is important for our understanding of migration ecology and ultimately conservation of migratory species. We studied the annual migration schedules of European nightjar, a large nocturnal insectivore and compared it with two other larger ...

  4. Dynamics and Thermodynamics of Molecular Machines

    DEFF Research Database (Denmark)

    Golubeva, Natalia

    2014-01-01

    to their microscopic size, molecular motors are governed by principles fundamentally different from those describing the operation of man-made motors such as car engines. In this dissertation the dynamic and thermodynamic properties of molecular machines are studied using the tools of nonequilibrium statistical......Molecular machines, or molecular motors, are small biophysical devices that perform a variety of essential metabolic processes such as DNA replication, protein synthesis and intracellular transport. Typically, these machines operate by converting chemical energy into motion and mechanical work. Due...... mechanics. The first part focuses on noninteracting molecular machines described by a paradigmatic continuum model with the aim of comparing and contrasting such a description to the one offered by the widely used discrete models. Many molecular motors, for example, kinesin involved in cellular cargo...

  5. Meal size is a critical driver of weight gain in early childhood

    OpenAIRE

    Syrad, Hayley; Llewellyn, Clare H.; Johnson, Laura; Boniface, David; Jebb, Susan A.; van Jaarsveld, Cornelia H. M.; Wardle, Jane

    2016-01-01

    Larger serving sizes and more frequent eating episodes have been implicated in the rising prevalence of obesity at a population level. This study examines the relative contributions of meal size and frequency to weight gain in a large sample of British children. Using 3-day diet diaries from 1939 children aged 21 months from the Gemini twin cohort, we assessed prospective associations between meal size, meal frequency and weight gain from two to five years. Separate longitudinal analyses demo...

  6. Thermodynamic Stability of Structure H Hydrates Based on the Molecular Properties of Large Guest Molecules

    OpenAIRE

    Tezuka, Kyoichi; Taguchi, Tatsuhiko; Alavi, Saman; Sum, Amadeu K.; Ohmura, Ryo

    2012-01-01

    This paper report analyses of thermodynamic stability of structure-H clathrate hydrates formed with methane and large guest molecules in terms of their gas phase molecular sizes and molar masses for the selection of a large guest molecule providing better hydrate stability. We investigated the correlation among the gas phase molecular sizes, the molar masses of large molecule guest substances, and the equilibrium pressures. The results suggest that there exists a molecular-size value for the ...

  7. Body size evolution in insular speckled rattlesnakes (Viperidae: Crotalus mitchellii.

    Directory of Open Access Journals (Sweden)

    Jesse M Meik

    2010-03-01

    Full Text Available Speckled rattlesnakes (Crotalus mitchellii inhabit multiple islands off the coast of Baja California, Mexico. Two of the 14 known insular populations have been recognized as subspecies based primarily on body size divergence from putative mainland ancestral populations; however, a survey of body size variation from other islands occupied by these snakes has not been previously reported. We examined body size variation between island and mainland speckled rattlesnakes, and the relationship between body size and various island physical variables among 12 island populations. We also examined relative head size among giant, dwarfed, and mainland speckled rattlesnakes to determine whether allometric differences conformed to predictions of gape size (and indirectly body size evolving in response to shifts in prey size.Insular speckled rattlesnakes show considerable variation in body size when compared to mainland source subspecies. In addition to previously known instances of gigantism on Angel de la Guarda and dwarfism on El Muerto, various degrees of body size decrease have occurred frequently in this taxon, with dwarfed rattlesnakes occurring mostly on small, recently isolated, land-bridge islands. Regression models using the Akaike information criterion (AIC showed that mean SVL of insular populations was most strongly correlated with island area, suggesting the influence of selection for different body size optima for islands of different size. Allometric differences in head size of giant and dwarf rattlesnakes revealed patterns consistent with shifts to larger and smaller prey, respectively.Our data provide the first example of a clear relationship between body size and island area in a squamate reptile species; among vertebrates this pattern has been previously documented in few insular mammals. This finding suggests that selection for body size is influenced by changes in community dynamics that are related to graded differences in area over

  8. Effects of sub-domain structure on initial magnetization curve and domain size distribution of stacked media

    International Nuclear Information System (INIS)

    Sato, S.; Kumagai, S.; Sugita, R.

    2015-01-01

    In this paper, in order to confirm the sub-domain structure in stacked media demagnetized with in-plane field, initial magnetization curves and magnetic domain size distribution were investigated. Both experimental and simulation results showed that an initial magnetization curve for the medium demagnetized with in-plane field (MDI) initially rose faster than that for the medium demagnetized with perpendicular field (MDP). It is inferred that this is because the MDI has a larger number of domain walls than the MDP due to the existence of the sub-domains, resulting in an increase in the probability of domain wall motion. Dispersion of domain size for the MDI was larger than that for the MDP. This is because sub-domains are formed not only inside the domain but also at the domain boundary region, and they change the position of the domain boundary to affect the domain size. - Highlights: • An initial magnetization curve for MDI initially rose faster than that for MDP. • Dispersion of domain size for the MDI was larger than that for the MDP. • Experimental and simulation results can be explained by existence of sub-domains

  9. The Cost of Class Size Reduction: Advice for Policymakers. RAND Graduate School Dissertation.

    Science.gov (United States)

    Reichardt, Robert E.

    This dissertation provides information to state-level policymakers that will help them avoid two implementation problems seen in the past in California's class-size-reduction (CSR) reform. The first problem was that flat, per student reimbursement did not adequately cover costs in districts with larger pre-CSR class-sizes or smaller schools. The…

  10. Chefs' opinions of restaurant portion sizes.

    Science.gov (United States)

    Condrasky, Marge; Ledikwe, Jenny H; Flood, Julie E; Rolls, Barbara J

    2007-08-01

    The objectives were to determine who establishes restaurant portion sizes and factors that influence these decisions, and to examine chefs' opinions regarding portion size, nutrition information, and weight management. A survey was distributed to chefs to obtain information about who is responsible for determining restaurant portion sizes, factors influencing restaurant portion sizes, what food portion sizes are being served in restaurants, and chefs' opinions regarding nutrition information, health, and body weight. The final sample consisted of 300 chefs attending various culinary meetings. Executive chefs were identified as being primarily responsible for establishing portion sizes served in restaurants. Factors reported to have a strong influence on restaurant portion sizes included presentation of foods, food cost, and customer expectations. While 76% of chefs thought that they served "regular" portions, the actual portions of steak and pasta they reported serving were 2 to 4 times larger than serving sizes recommended by the U.S government. Chefs indicated that they believe that the amount of food served influences how much patrons consume and that large portions are a problem for weight control, but their opinions were mixed regarding whether it is the customer's responsibility to eat an appropriate amount when served a large portion of food. Portion size is a key determinant of energy intake, and the results from this study suggest that cultural norms and economic value strongly influence the determination of restaurant portion sizes. Strategies are needed to encourage chefs to provide and promote portions that are appropriate for customers' energy requirements.

  11. Effects of Particle Size on the Shear Behavior of Coarse Grained Soils Reinforced with Geogrid.

    Science.gov (United States)

    Kim, Daehyeon; Ha, Sungwoo

    2014-02-07

    In order to design civil structures that are supported by soils, the shear strength parameters of soils are required. Due to the large particle size of coarse-grained soils, large direct shear tests should be performed. In this study, large direct shear tests on three types of coarse grained soils (4.5 mm, 7.9 mm, and 15.9 mm) were performed to evaluate the effects of particle size on the shear behavior of coarse grained soils with/without geogrid reinforcements. Based on the direct shear test results, it was found that, in the case of no-reinforcement, the larger the maximum particle size became, the larger the friction angle was. Compared with the no-reinforcement case, the cases reinforced with either soft geogrid or stiff geogrid have smaller friction angles. The cohesion of the soil reinforced with stiff geogrid was larger than that of the soil reinforced with soft geogrid. The difference in the shear strength occurs because the case with a stiff geogrid has more soil to geogrid contact area, leading to the reduction in interlocking between soil particles.

  12. Preparation of size-tunable, highly monodisperse PVP-protected Pt-nanoparticles by seed-mediated growth

    International Nuclear Information System (INIS)

    Koebel, Matthias M.; Jones, Louis C.; Somorjai, Gabor A.

    2008-01-01

    We demonstrate a preparative method which produces highly monodisperse Pt-nanoparticles of tunable size without the external addition of seed particles. Hexachloroplatinic acid is dosed slowly to an ethylene glycol solution at 120 o C and reduced in the presence of a stabilizing polymer poly-N-vinylpyrrolidone (PVP). Slow addition of the Pt-salt will first lead to the formation of nuclei (seeds) which then grow further to produce larger particles of any desired size between 3 and 8 nm. The amount of added hexachloroplatinic acid precursor controls the size of the final nanoparticle product. TEM was used to determine size and morphology and to confirm the crystalline nature of the nanoparticles. Good reproducibility of the technique was demonstrated. Above 7 nm, the particle shape and morphology changes suddenly indicating a change in the deposition selectivity of the Pt-precursor from (100) towards (111) crystal faces and breaking up of larger particles into smaller entities.

  13. Constraints on extra dimensions from precision molecular spectroscopy

    NARCIS (Netherlands)

    Salumbides, E.J.; Schellekens, A.N.; Gato-Rivera, B.; Ubachs, W.M.G.

    2015-01-01

    Accurate investigations of quantum-level energies in molecular systems are shown to provide a testing ground to constrain the size of compactified extra dimensions. This is made possible by recent progress in precision metrology with ultrastable lasers on energy levels in neutral molecular hydrogen

  14. Molecular dynamics using quasielastic neutron scattering

    CERN Document Server

    Mitra, S

    2003-01-01

    Quasielastic neutron scattering (QENS) technique is well suited to study the molecular motions (rotations and translations) in solids or liquids. It offers a unique possibility of analysing spatial dimensions of atomic or molecular processes in their development over time. We describe here some of the systems studied using the QENS spectrometer, designed, developed and commissioned at Dhruva reactor in Trombay. We have studied a variety of systems to investigate the molecular motion, for example, simple molecular solids, molecules adsorbed in confined medium like porous systems or zeolites, monolayer-protected nano-sized metal clusters, water in Portland cement as it cures with time, etc. (author)

  15. Poly(styrene-co-butadiene) random copolymer thin films and nanostructures on a mica surface: morphology and contact angles of nanodroplets.

    Science.gov (United States)

    McClements, Jake; Buffone, Cosimo; Shaver, Michael P; Sefiane, Khellil; Koutsos, Vasileios

    2017-09-20

    The self-assembly of poly(styrene-co-butadiene) random copolymers on mica surfaces was studied by varying solution concentrations and polymer molecular weights. Toluene solutions of the poly(styrene-co-butadiene) samples were spin coated onto a mica surface and the resulting polymer morphology was investigated by atomic force microscopy. At higher concentrations, thin films formed with varying thicknesses; some dewetting was observed which depended on the molecular weight. Total dewetting did not occur despite the polymer's low glass transition temperature. Instead, partial dewetting was observed suggesting that the polymer was in a metastable equilibrium state. At lower concentrations, spherical cap shaped nanodroplets formed with varying sizes from single polymer chains to aggregates containing millions of chains. As the molecular weight was increased, fewer aggregates were observed on the surface, albeit with larger sizes resulting from increased solution viscosities and more chain entanglements at higher molecular weights. The contact angles of the nanodroplets were shown to be size dependent. A minimum contact angle occurs for droplets with radii of 100-250 nm at each molecular weight. Droplets smaller than 100 nm showed a sharp increase in contact angle; attributed to an increase in the elastic modulus of the droplets, in addition, to a positive line tension value. Droplets larger than 250 nm also showed an increased contact angle due to surface heterogeneities which cannot be avoided for larger droplets. This increase in contact angle plateaus as the droplet size reaches the macroscopic scale.

  16. The relationship between house size and life cycle energy demand: Implications for energy efficiency regulations for buildings

    International Nuclear Information System (INIS)

    Stephan, André; Crawford, Robert H.

    2016-01-01

    House size has significantly increased over the recent decades in many countries. Larger houses often have a higher life cycle energy demand due to their increased use of materials and larger area to heat, cool and light. Yet, most energy efficiency regulations for buildings fail to adequately include requirements for addressing the energy demand associated with house size. This study quantifies the effect of house size on life cycle energy demand in order to inform future regulations. It uses a parametric model of a typical detached house in Melbourne, Australia and varies its floor area from 100 to 392 m"2 for four different household sizes. Both initial and recurrent embodied energy requirements are quantified using input-output-based hybrid analysis and operational energy is calculated in primary energy terms over 50 years. Results show that the life cycle energy demand increases at a slower rate compared to house size. Expressing energy efficiency per m"2 therefore favours large houses while these require more energy. Also, embodied energy represents 26–50% across all variations. Building energy efficiency regulations should incorporate embodied energy, correct energy intensity thresholds for house size and use multiple functional units to measure efficiency. These measures may help achieve greater net energy reductions. - Highlights: • The life cycle energy demand (LCE) is calculated for 90 house sizes and 4 household sizes. • The LCE is sublinearly correlated with house size. • Larger houses appear to be more energy efficient per m"2 while they use more energy overall. • Embodied energy (EE) represents up to 52% of the LCE over 50 years. • Building energy efficiency regulations need to consider house size and EE.

  17. Surface Effect on Oil Transportation in Nanochannel: a Molecular Dynamics Study.

    Science.gov (United States)

    Zheng, Haixia; Du, Yonggang; Xue, Qingzhong; Zhu, Lei; Li, Xiaofang; Lu, Shuangfang; Jin, Yakang

    2017-12-01

    In this work, we investigate the dynamics mechanism of oil transportation in nanochannel using molecular dynamics simulations. It is demonstrated that the interaction between oil molecules and nanochannel has a great effect on the transportation properties of oil in nanochannel. Because of different interactions between oil molecules and channel, the center of mass (COM) displacement of oil in a 6-nm channel is over 30 times larger than that in a 2-nm channel, and the diffusion coefficient of oil molecules at the center of a 6-nm channel is almost two times more than that near the channel surface. Besides, it is found that polarity of oil molecules has the effect on impeding oil transportation, because the electrostatic interaction between polar oil molecules and channel is far larger than that between nonpolar oil molecules and channel. In addition, channel component is found to play an important role in oil transportation in nanochannel, for example, the COM displacement of oil in gold channel is very few due to great interaction between oil and gold substrate. It is also found that nano-sized roughness of channel surface greatly influences the speed and flow pattern of oil. Our findings would contribute to revealing the mechanism of oil transportation in nanochannels and therefore are very important for design of oil extraction in nanochannels.

  18. Molecular mobility of nematic E7 confined to molecular sieves with a low filling degree.

    Science.gov (United States)

    Brás, A R; Frunza, S; Guerreiro, L; Fonseca, I M; Corma, A; Frunza, L; Dionísio, M; Schönhals, A

    2010-06-14

    The nematic liquid crystalline mixture E7 was confined with similar filling degrees to molecular sieves with constant composition but different pore diameters (from 2.8 to 6.8 nm). Fourier transform infrared analysis proved that the E7 molecules interact via the cyanogroup with the pore walls of the molecular sieves. The molecular dynamics of the system was investigated by broadband dielectric spectroscopy (10(-2)-10(9) Hz) covering a wide temperature range of approximately 200 K from temperatures well above the isotropic-nematic transition down to the glass transition of bulk E7. A variety of relaxation processes is observed including two modes that are located close to the bulk behavior in its temperature dependence. For all confined samples, two relaxation processes, at frequencies lower than the processes observed for the bulk, were detected. At lower temperatures, their relaxation rates have different temperature dependencies whereas at higher temperatures, they seem to collapse into one chart. The temperature dependence of the slowest process (S-process) obeys the Vogel-Fulcher-Tammann law indicating a glassy dynamics of the E7 molecules anchored to the pore surface. The pore size dependence of both the Vogel temperature and fragility revealed a steplike transition around 4 nm pore size, which indicates a transition from a strong to a fragile behavior. The process with a relaxation rate in between the bulklike and the S-process (I-process) shows no dependence on the pore size. The agreement of the I-process with the behavior of a 5CB surface layer adsorbed on nonporous silica leads to the assignment of E7 molecules anchored at the outer surface of the microcrystals of the molecular sieves.

  19. Spatial variation in egg size of a top predator: Interplay of body size and environmental factors?

    Science.gov (United States)

    Louzao, Maite; Igual, José M.; Genovart, Meritxell; Forero, Manuela G.; Hobson, Keith A.; Oro, Daniel

    2008-09-01

    It is expected that nearby populations are constrained by the same ecological features shaping in turn similarity in their ecological traits. Here, we studied the spatio-temporal variability in egg size among local populations of the critically endangered Balearic shearwater Puffinus mauretanicus, a top marine predator endemic to the western Mediterranean region. Specifically we assessed whether this trait was influenced by maternal body size, as an indicator of a genetic component, and feeding ecology (through stable-carbon and nitrogen-isotope measurements), as an indicator of environmental factors. We found that egg size varied among local populations, an unexpected result at such a small spatial scale. Body size differences at the local population level only partially explained such differences. Blood isotope measurements also differed among local populations. Values of δ 15N suggested inter-population differences in trophic level, showing a similar general pattern with egg size, and suggesting a nutritional link between them whereby egg size was affected by differences in feeding resources and/or behaviour. Values of δ 13C suggested that local populations did not differ in foraging habits with respect to benthic- vs. pelagic-based food-webs. Egg size did not vary among years as did breeding performance, suggesting that a differential temporal window could affect both breeding parameters in relation to food availability. The absence of a relationship between breeding performance and egg size suggested that larger eggs might only confer an advantage during harsh conditions. Alternatively parental quality could greatly affect breeding performance. We showed that inter-population differences in egg size could be influenced by both body size and environmental factors.

  20. The Effect of Visual Feedback on Writing Size in Parkinson’s Disease

    Directory of Open Access Journals (Sweden)

    Adriaan R. E. Potgieser

    2015-01-01

    Full Text Available Parkinson’s disease (PD leads to impairment in multiple cognitive domains. Micrographia is a relatively early PD sign of visuomotor dysfunction, characterized by a global reduction in writing size and a decrement in size during writing. Here we aimed to investigate the effect of withdrawal of visual feedback on writing size in patients with PD. Twenty-five patients with non-tremor-dominant PD without cognitive dysfunction and twenty-five age-matched controls had to write a standard sentence with and without visual feedback. We assessed the effect of withdrawal of visual feedback by measuring vertical word size (i, horizontal length of the sentence (ii, and the summed horizontal word length without interspacing (iii, comparing patients with controls. In both patients and controls, writing was significantly larger without visual feedback. This enlargement did not significantly differ between the groups. Smaller handwriting significantly correlated with increased disease severity. Contrary to previous observations that withdrawal of visual feedback caused increased writing size in specifically PD, we did not find differences between patients and controls. Both groups wrote larger without visual feedback, which adds insight in general neuronal mechanisms underlying the balance between feed-forward and feedback in visuomotor control, mechanisms that also hold for grasping movements.