WorldWideScience

Sample records for understanding potential mechanisms

  1. Marine phospholipids: The current understanding of their oxidation mechanisms and potential uses for food fortification

    DEFF Research Database (Denmark)

    Lu, Henna Fung Sieng; Nielsen, Nina Skall; Baron, Caroline P.

    2017-01-01

    and storage of marine PL. For example, nonenzymatic browning reactions may occur between lipid oxidation products and primary amine group from phosphatidylethanolamine or amino acid residues that are present inmarine PL. Therefore, marine PL contain products from nonenzymatic browning and lipid oxidation...... reactions, namely, Strecker aldehydes, pyrroles, oxypolymers, and other impurities that may positively or negatively affect the oxidative stability and quality of marine PL. This review was undertaken to provide the industry and academia with an overview of the current understanding of the quality changes...... taking place in PL during their production and their storage as well as with regards to their utilization for food fortification....

  2. Understanding Defense Mechanisms.

    Science.gov (United States)

    Cramer, Phebe

    2015-12-01

    Understanding defense mechanisms is an important part of psychotherapy. In this article, we trace the history of the concept of defense, from its origin with Freud to current views. The issue of defense as an unconscious mechanism is examined. The question of whether defenses are pathological, as well as their relation to pathology, is discussed. The effect of psychotherapy on the use of defenses, and their relation to a therapeutic alliance is explored. A series of empirical research studies that demonstrate the functioning of defense mechanisms and that support the theory is presented. Research also shows that as part of normal development, different defenses emerge at different developmental periods, and that gender differences in defense use occur.

  3. Understanding mechanical ventilators.

    Science.gov (United States)

    Chatburn, Robert L

    2010-12-01

    The respiratory care academic community has not yet adopted a standardized system for classifying and describing modes of ventilation. As a result, there is enough confusion that patient care, clinician education and even ventilator sales are all put at risk. This article summarizes a ventilator mode taxonomy that has been extensively published over the last 15 years. Specifically, the classification system has three components: a description of the control variables within breath; a description of the sequence of mandatory and spontaneous breaths; and a specification for the targeting scheme. This three-level specification provides scalability of detail to make the mode description appropriate for the particular need. At the bedside, we need only refer to a mode briefly using the first or perhaps first and second components. To distinguish between similar modes and brand names, we would need to include all components. This taxonomy uses the equation of motion for the respiratory system as the underlying theoretical framework. All terms relevant to describing modes of mechanical ventilation are defined in an extensive appendix.

  4. Understanding the mechanisms of lung mechanical stress

    Directory of Open Access Journals (Sweden)

    C.S.N.B. Garcia

    2006-06-01

    Full Text Available Physical forces affect both the function and phenotype of cells in the lung. Bronchial, alveolar, and other parenchymal cells, as well as fibroblasts and macrophages, are normally subjected to a variety of passive and active mechanical forces associated with lung inflation and vascular perfusion as a result of the dynamic nature of lung function. These forces include changes in stress (force per unit area or strain (any forced change in length in relation to the initial length and shear stress (the stress component parallel to a given surface. The responses of cells to mechanical forces are the result of the cell's ability to sense and transduce these stimuli into intracellular signaling pathways able to communicate the information to its interior. This review will focus on the modulation of intracellular pathways by lung mechanical forces and the intercellular signaling. A better understanding of the mechanisms by which lung cells transduce physical forces into biochemical and biological signals is of key importance for identifying targets for the treatment and prevention of physical force-related disorders.

  5. Understanding Bohmian mechanics: A dialogue

    OpenAIRE

    Tumulka, Roderich

    2004-01-01

    This paper is an introduction to the ideas of Bohmian mechanics, an interpretation of quantum mechanics in which the observer plays no fundamental role. Bohmian mechanics describes, instead of probabilities of measurement results, objective microscopic events. In recent years, Bohmian mechanics has attracted increasing attention by researchers. The form of a dialogue allows me to address questions about the Bohmian view that often arise.

  6. Understanding Mechanical Design with Respect to Manufacturability

    Science.gov (United States)

    Mondell, Skyler

    2010-01-01

    At the NASA Prototype Development Laboratory in Kennedy Space Center, Fl, several projects concerning different areas of mechanical design were undertaken in order to better understand the relationship between mechanical design and manufacturabiIity. The assigned projects pertained specifically to the NASA Space Shuttle, Constellation, and Expendable Launch Vehicle programs. During the work term, mechanical design practices relating to manufacturing processes were learned and utilized in order to obtain an understanding of mechanical design with respect to manufacturability.

  7. Understanding Mechanisms of Radiological Contamination

    Energy Technology Data Exchange (ETDEWEB)

    Rick Demmer; John Drake; Ryan James, PhD

    2014-03-01

    Over the last 50 years, the study of radiological contamination and decontamination has expanded significantly. This paper addresses the mechanisms of radiological contamination that have been reported and then discusses which methods have recently been used during performance testing of several different decontamination technologies. About twenty years ago the Idaho Nuclear Technology Engineering Center (INTEC) at the INL began a search for decontamination processes which could minimize secondary waste. In order to test the effectiveness of these decontamination technologies, a new simulated contamination, termed SIMCON, was developed. SIMCON was designed to replicate the types of contamination found on stainless steel, spent fuel processing equipment. Ten years later, the INL began research into methods for simulating urban contamination resulting from a radiological dispersal device (RDD). This work was sponsored by the Defense Advanced Research Projects Agency (DARPA) and included the initial development an aqueous application of contaminant to substrate. Since 2007, research sponsored by the US Environmental Protection Agency (EPA) has advanced that effort and led to the development of a contamination method that simulates particulate fallout from an Improvised Nuclear Device (IND). The IND method diverges from previous efforts to create tenacious contamination by simulating a reproducible “loose” contamination. Examining these different types of contamination (and subsequent decontamination processes), which have included several different radionuclides and substrates, sheds light on contamination processes that occur throughout the nuclear industry and in the urban environment.

  8. Understanding biochar mechanisms for practical implementation

    Energy Technology Data Exchange (ETDEWEB)

    Glaser, Bruno [Halle-Wittenberg Univ. (Germany). Inst. fuer Agrar- und Ernaehrungeswissenschaften Bodenbiogeochemie; Kammann, Claudia [Arbeitskreis zur Nutzung von Sekundaerrohstoffen und fuer Klimaschutz (ANS) e.V., Braunschweig (Germany). Fachausschuss Biokohle; Hochschule Geisenheim Univ. (Germany). Klimafolgenforschung-Klimawandel in Spezialkulturen; Loewen, Achim (ed.) [Arbeitskreis zur Nutzung von Sekundaerrohstoffen und fuer Klimaschutz (ANS) e.V., Braunschweig (Germany); HAWK Hochschule fuer Angewandte Wissenschaft und Kunst Hildesheim, Holzminden, Goettingen (Germany). Fachgebiet Nachhaltige Energie- und Umwelttechnik NEUtec

    2015-07-01

    The conference on ''understanding biochar mechanisms for practical implementation'' 2015 at the Geisenheim University aims at understanding biochar mechanism, that are crucial for beneficial and safety biochar technology implementation. Further issues are ecotoxicology, biochar in agriculture, horticulture, and animal husbandry. Practical issues concern analysis and characterization of technological processes, sustainable uses and certification, regulation and marketing aspects. The Conference is structured in 10 sessions.

  9. Singular potentials in quantum mechanics

    Energy Technology Data Exchange (ETDEWEB)

    Aguilera-Navarro, V.C. [Instituto de Fisica Teorica (IFT), Sao Paulo, SP (Brazil); Koo, E. Ley [Universidad Nacional Autonoma de Mexico, Mexico City (Mexico). Inst. de Fisica

    1995-10-01

    This paper is a review of some mathematical methods as recently developed and applied to deal with singular potentials in Quantum Mechanics. Regular and singular perturbative methods as well as variational treatments are considered. (author). 25 refs.

  10. Understanding and exploring the potentials of household water treatment methods for volatile disinfection by-products control: Kinetics, mechanisms, and influencing factors.

    Science.gov (United States)

    Ma, Shengcun; Gan, Yiqun; Chen, Baiyang; Tang, Zhong; Krasner, Stuart

    2017-01-05

    This study systematically evaluates the capabilities of five types of household water treatment (HWT) methods (including boiler heating, microwave irradiation, pouring, stirring, and shaking) on the removals of four regulated trihalomethanes (THM 4 ) and three iodinated halomethanes (IHMs) under a variety of conditions simulative of residential uses. Overall, the results clearly showed promising capabilities of all five HWT methods in controlling volatile disinfection by-products (DBPs), and heating with a boiler was the most effective approach among all methods due to the synergistic effects of water turbulence and bubbling phenomena. A contemporary boiler equipped with an automatic switch-off function reduced on average 92% of seven halomethanes (HM 7 ) at favourable conditions. The removal increased significantly with increasing initial concentrations and the rates correlated well with the logarithmic Henry's law constants and molecular weights of compounds, with triiodomethane being the most refractory species. Meanwhile, the importance of water handling habits was revealed, including power input, operation time, volume, heating/cooling speed, cooling method, and capping conditions. The findings hence explored the potentials of HWTs on DBP control and pointed out a potential limit to DBP epidemiology studies that do not consider water handling habits. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Improving students' understanding of quantum mechanics

    Science.gov (United States)

    Singh, Chandralekha

    2011-03-01

    Learning quantum mechanics is especially challenging, in part due to the abstract nature of the subject. We have been conducting investigations of the difficulties that students have in learning quantum mechanics. To help improve student understanding of quantum concepts, we are developing quantum interactive learning tutorials (QuILTs) as well as tools for peer-instruction. The goal of QuILTs and peer-instruction tools is to actively engage students in the learning process and to help them build links between the formalism and the conceptual aspects of quantum physics without compromising the technical content. They focus on helping students integrate qualitative and quantitative understanding, confront and resolve their misconceptions and difficulties, and discriminate between concepts that are often confused. In this talk, I will give examples from my research in physics education of how students' prior knowledge relevant for quantum mechanics can be assessed, and how learning tools can be designed to help students develop a robust knowledge structure and critical thinking skills. Supported by the National Science Foundation.

  12. Advanced waterflooding in chalk reservoirs: Understanding of underlying mechanisms

    DEFF Research Database (Denmark)

    Zahid, Adeel; Sandersen, Sara Bülow; Stenby, Erling Halfdan

    2011-01-01

    Over the last decade, a number of studies have shown SO42−, Ca2+ and Mg2+ to be potential determining ions, which may be added to the injected brine for improving oil recovery during waterflooding in chalk reservoirs. However the understanding of the mechanism leading to an increase in oil recove...... of a microemulsion phase could be the possible reasons for the observed increase in oil recovery with sulfate ions at high temperature in chalk reservoirs besides the mechanism of the rock wettability alteration, which has been reported in most previous studies.......Over the last decade, a number of studies have shown SO42−, Ca2+ and Mg2+ to be potential determining ions, which may be added to the injected brine for improving oil recovery during waterflooding in chalk reservoirs. However the understanding of the mechanism leading to an increase in oil recovery...

  13. Understanding Mechanism of Photocatalytic Microbial Decontamination of Environmental Wastewater

    Directory of Open Access Journals (Sweden)

    Chhabilal Regmi

    2018-02-01

    Full Text Available Several photocatalytic nanoparticles are synthesized and studied for potential application for the degradation of organic and biological wastes. Although these materials degrade organic compounds by advance oxidation process, the exact mechanisms of microbial decontamination remains partially known. Understanding the real mechanisms of these materials for microbial cell death and growth inhibition helps to fabricate more efficient semiconductor photocatalyst for large-scale decontamination of environmental wastewater or industries and hospitals/biomedical labs generating highly pathogenic bacteria and toxic molecules containing liquid waste by designing a reactor. Recent studies on microbial decontamination by photocatalytic nanoparticles and their possible mechanisms of action is highlighted with examples in this mini review.

  14. Understanding the molecular mechanisms of reprogramming

    Energy Technology Data Exchange (ETDEWEB)

    Krause, Marie N. [Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla 92037, CA (United States); University Hospital of Würzburg, Department of Pediatrics, 2 Josef-Schneiderstrasse, 97080 Würzburg (Germany); Sancho-Martinez, Ignacio [Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla 92037, CA (United States); Centre for Stem Cells and Regenerative Medicine, King' s College London, 28th Floor, Tower Wing, Guy' s Hospital, Great Maze Pond, London (United Kingdom); Izpisua Belmonte, Juan Carlos, E-mail: belmonte@salk.edu [Gene Expression Laboratory, Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla 92037, CA (United States)

    2016-05-06

    Despite the profound and rapid advancements in reprogramming technologies since the generation of the first induced pluripotent stem cells (iPSCs) in 2006[1], the molecular basics of the process and its implications are still not fully understood. Recent work has suggested that a subset of TFs, so called “Pioneer TFs”, play an important role during the stochastic phase of iPSC reprogramming [2–6]. Pioneer TFs activities differ from conventional transcription factors in their mechanism of action. They bind directly to condensed chromatin and elicit a series of chromatin remodeling events that lead to opening of the chromatin. Chromatin decondensation by pioneer factors progressively occurs during cell division and in turn exposes specific gene promoters in the DNA to which TFs can now directly bind to promoters that are readily accessible[2, 6]. Here, we will summarize recent advancements on our understanding of the molecular mechanisms underlying reprogramming to iPSC as well as the implications that pioneer Transcription Factor activities might play during different lineage conversion processes. - Highlights: • Pioneer transcription factor activity underlies the initial steps of iPSC generation. • Reprogramming can occur by cis- and/or trans- reprogramming events. • Cis-reprogramming implies remodeling of the chromatin for enabling TF accessibility. • Trans-reprogramming encompasses direct binding of Tfs to their target gene promoters.

  15. Towards an understanding of the nuclear potential

    International Nuclear Information System (INIS)

    Richards, D.G.

    1989-01-01

    The formalism for investigating the anti Qqanti Qq system on the lattice is constructed. We describe how the model may be used to study the nuclear potential, and present some preliminary results on the range of the nuclear force. (orig.)

  16. Understanding mechanisms of toxicity: Insights from drug discovery research

    International Nuclear Information System (INIS)

    Houck, Keith A.; Kavlock, Robert J.

    2008-01-01

    Toxicology continues to rely heavily on use of animal testing for prediction of potential for toxicity in humans. Where mechanisms of toxicity have been elucidated, for example endocrine disruption by xenoestrogens binding to the estrogen receptor, in vitro assays have been developed as surrogate assays for toxicity prediction. This mechanistic information can be combined with other data such as exposure levels to inform a risk assessment for the chemical. However, there remains a paucity of such mechanistic assays due at least in part to lack of methods to determine specific mechanisms of toxicity for many toxicants. A means to address this deficiency lies in utilization of a vast repertoire of tools developed by the drug discovery industry for interrogating the bioactivity of chemicals. This review describes the application of high-throughput screening assays as experimental tools for profiling chemicals for potential for toxicity and understanding underlying mechanisms. The accessibility of broad panels of assays covering an array of protein families permits evaluation of chemicals for their ability to directly modulate many potential targets of toxicity. In addition, advances in cell-based screening have yielded tools capable of reporting the effects of chemicals on numerous critical cell signaling pathways and cell health parameters. Novel, more complex cellular systems are being used to model mammalian tissues and the consequences of compound treatment. Finally, high-throughput technology is being applied to model organism screens to understand mechanisms of toxicity. However, a number of formidable challenges to these methods remain to be overcome before they are widely applicable. Integration of successful approaches will contribute towards building a systems approach to toxicology that will provide mechanistic understanding of the effects of chemicals on biological systems and aid in rationale risk assessments

  17. Understanding molecular structure from molecular mechanics.

    Science.gov (United States)

    Allinger, Norman L

    2011-04-01

    Molecular mechanics gives us a well known model of molecular structure. It is less widely recognized that valence bond theory gives us structures which offer a direct interpretation of molecular mechanics formulations and parameters. The electronic effects well-known in physical organic chemistry can be directly interpreted in terms of valence bond structures, and hence quantitatively calculated and understood. The basic theory is outlined in this paper, and examples of the effects, and their interpretation in illustrative examples is presented.

  18. Understanding and potentially reducing second breast cancer

    International Nuclear Information System (INIS)

    Brenner, D.

    2011-01-01

    Full text: Long term survival after breast cancer diagnosis has increased markedly in the last decade: 15-year relative survival after breast cancer diagnosis is now 75% in the US. Associated with these excellent survival prospects, however, long term studies suggest that contralateral second breast cancer rates are in the range from 10 to 15% at 15 years post treatment, and are still higher for BRCA1/2 carriers, as well as for still longer term survivors. These second cancer risks are much higher than those for a comparable healthy woman to develop a first breast cancer. It follows that women with breast cancer are highly prone to develop a second breast cancer. We propose here a new option for reducing the disturbingly high risk of a contralateral second breast cancer. in patients with both estrogen positive and negative primary breast cancer: prophylactic mammary irradiation (PMI) of the contralateral breast. The rationale behind PMI is evidence that standard post-Iumpectomy radiotherapy of the affected (ipsilateral) breast substantially reduces the long-term genetically-based second cancer risk in the ipsilateral breast, by killing the existing premalignant cells in that breast. This suggests that there are relatively few premalignant cells in the breast (hundreds or thousands, not millions), so even a fairly modest radiation cell-kill level across the whole breast would be expected to kill essentially all of them. If this is so, then a modest radiation dose-much lower than that to the affected breast--delivered uniformly to the whole contralateral breast, and typically delivered at the same time as the radiotherapy of the ipsilateral breast, would have the potential to markedly reduce second-cancer risks in the contralateral breast by killing essentially all the pre-malignant cells in that breast while causing only a very low level of radiation-induced sequelae. Therefore we hypothesize that low-dose prophylactic mammary irradiation of the contralateral breast

  19. Understanding Kinetic Energy paradox in Quantum Mechanics

    OpenAIRE

    Kornyushin, Yuri

    2008-01-01

    A concept of Kinetic Energy in Quantum Mechanics is analyzed. Kinetic Energy is not zero in many cases where there are no motion and flux. This paradox can be understood, using expansion of the wave function in Fourier integral, that is on the basis of virtual plane waves.

  20. Understanding and imitating unfamiliar actions: distinct underlying mechanisms.

    Directory of Open Access Journals (Sweden)

    Joana C Carmo

    Full Text Available The human "mirror neuron system" has been proposed to be the neural substrate that underlies understanding and, possibly, imitating actions. However, since the brain activity with mirror properties seems insufficient to provide a good description for imitation of actions outside one's own repertoire, the existence of supplementary processes has been proposed. Moreover, it is unclear whether action observation requires the same neural mechanisms as the explicit access to their meaning. The aim of this study was two-fold as we investigated whether action observation requires different processes depending on 1 whether the ultimate goal is to imitate or understand the presented actions and 2 whether the to-be-imitated actions are familiar or unfamiliar to the subject. Participants were presented with both meaningful familiar actions and meaningless unfamiliar actions that they had to either imitate or discriminate later. Event-related Potentials were used as differences in brain activity could have been masked by the use of other techniques with lower temporal resolution. In the imitation task, a sustained left frontal negativity was more pronounced for meaningless actions than for meaningful ones, starting from an early time-window. Conversely, observing unfamiliar versus familiar actions with the intention of discriminating them led to marked differences over right centro-posterior scalp regions, in both middle and latest time-windows. These findings suggest that action imitation and action understanding may be sustained by dissociable mechanisms: while imitation of unfamiliar actions activates left frontal processes, that are likely to be related to learning mechanisms, action understanding involves dedicated operations which probably require right posterior regions, consistent with their involvement in social interactions.

  1. Understanding Liver Regeneration: From Mechanisms to Regenerative Medicine.

    Science.gov (United States)

    Gilgenkrantz, Hélène; Collin de l'Hortet, Alexandra

    2018-04-16

    Liver regeneration is a complex and unique process. When two-thirds of a mouse liver is removed, the remaining liver recovers its initial weight in approximately 10 days. The understanding of the mechanisms responsible for liver regeneration may help patients needing large liver resections or transplantation and may be applied to the field of regenerative medicine. All differentiated hepatocytes are capable of self-renewal, but different subpopulations of hepatocytes seem to have distinct proliferative abilities. In the setting of chronic liver diseases, a ductular reaction ensues in which liver progenitor cells (LPCs) proliferate in the periportal region. Although these LPCs have the capacity to differentiate into hepatocytes and biliary cells in vitro, their ability to participate in liver regeneration is far from clear. Their expansion has even been associated with increased fibrosis and poorer prognosis in chronic liver diseases. Controversies also remain on their origin: lineage studies in experimental mouse models of chronic injury have recently suggested that these LPCs originate from hepatocyte dedifferentiation, whereas in other situations, they seem to come from cholangiocytes. This review summarizes data published in the past 5 years in the liver regeneration field, discusses the mechanisms leading to regeneration disruption in chronic liver disorders, and addresses the potential use of novel approaches for regenerative medicine. Copyright © 2018 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  2. Understanding the mechanisms behind coking pressure: Relationship to pore structure

    Energy Technology Data Exchange (ETDEWEB)

    John J. Duffy; M. Castro Diaz; Colin E. Snape; Karen M. Steel; Merrick R. Mahoney [University of Nottingham, Nottingham (United Kingdom). Nottingham Fuel and Energy Centre, School of Chemical, Environmental and Mining Engineering

    2007-09-15

    Three low volatile coals A, B and C with oven wall pressures of 100 kPa, 60 kPa and 20 kPa respectively were investigated using high-temperature rheometry, {sup 1}H NMR, thermogravimetric analysis and SEM, with the primary aim to better understand the mechanisms behind the coking pressure phenomenon. Rheometer plate displacement measurements ({Delta}L) have shown differences in the expansion and contraction behaviour of the three coals, which seem to correlate with changes in rheological properties; while SEM images have shown that the expansion process coincides with development of pore structure. It is considered that the point of maximum plate height ({Delta}L{sub max}) prior to contraction may be indicative of a cell opening or pore network forming process, based on analogies with other foam systems. Such a process may be considered important for coking pressure since it provides a potential mechanism for volatile escape, relieving internal gas pressure and inducing charge contraction. For coal C, which has the highest fluidity {delta}L{sub max} occurs quite early in the softening process and consequently a large degree of contraction is observed; while for the lower fluidity coal B, the process is delayed since pore development and consequently wall thinning progress at a slower rate. When {Delta}L{sub max} is attained, a lower degree of contraction is observed because the event occurs closer to resolidification where the increasing viscosity/elasticity can stabilise the expanded pore structure. For coal A which is relatively high fluidity, but also high coking pressure, a greater degree of swelling is observed prior to cell rupture, which may be due to greater fluid elasticity during the expansion process. This excessive expansion is considered to be a potential reason for its high coking pressure. 58 refs., 15 figs., 1 tab.

  3. Quantum mechanical streamlines. I - Square potential barrier

    Science.gov (United States)

    Hirschfelder, J. O.; Christoph, A. C.; Palke, W. E.

    1974-01-01

    Exact numerical calculations are made for scattering of quantum mechanical particles hitting a square two-dimensional potential barrier (an exact analog of the Goos-Haenchen optical experiments). Quantum mechanical streamlines are plotted and found to be smooth and continuous, to have continuous first derivatives even through the classical forbidden region, and to form quantized vortices around each of the nodal points. A comparison is made between the present numerical calculations and the stationary wave approximation, and good agreement is found between both the Goos-Haenchen shifts and the reflection coefficients. The time-independent Schroedinger equation for real wavefunctions is reduced to solving a nonlinear first-order partial differential equation, leading to a generalization of the Prager-Hirschfelder perturbation scheme. Implications of the hydrodynamical formulation of quantum mechanics are discussed, and cases are cited where quantum and classical mechanical motions are identical.

  4. Understanding the Prospects and Potential for Improved Regional ...

    African Journals Online (AJOL)

    Understanding the Prospects and Potential for Improved Regional LIS Collaboration in the Developing World: An Empirical Study of LIS Departments in the GCC States. ... This is a qualitative research study, based on interviews with Heads of LIS Departments in the GCC states. The researchers emailed all Heads of LIS ...

  5. Understanding electron magnetic circular dichroism in a transition potential approach

    Science.gov (United States)

    Barthel, J.; Mayer, J.; Rusz, J.; Ho, P.-L.; Zhong, X. Y.; Lentzen, M.; Dunin-Borkowski, R. E.; Urban, K. W.; Brown, H. G.; Findlay, S. D.; Allen, L. J.

    2018-04-01

    This paper introduces an approach based on transition potentials for inelastic scattering to understand the underlying physics of electron magnetic circular dichroism (EMCD). The transition potentials are sufficiently localized to permit atomic-scale EMCD. Two-beam and three-beam systematic row cases are discussed in detail in terms of transition potentials for conventional transmission electron microscopy, and the basic symmetries which arise in the three-beam case are confirmed experimentally. Atomic-scale EMCD in scanning transmission electron microscopy (STEM), using both a standard STEM probe and vortex beams, is discussed.

  6. AUTOMOTIVE DIESEL MAINTENANCE 2. UNIT I, UNDERSTANDING MECHANICAL CLUTCHES.

    Science.gov (United States)

    Minnesota State Dept. of Education, St. Paul. Div. of Vocational and Technical Education.

    ONE OF A 25-MODULE COURSE DESIGNED TO UPGRADE THE JOB SKILLS AND TECHNICAL KNOWLEDGE OF DIESEL MAINENANCE MECHANICS THIS MATERIAL WAS DEVELOPED BY INDUSTRIAL TRAINING AND SUBJECT-MATTER SPECIALISTS AND TESTED IN INDUSTRIAL TRAINING SITUATIONS. THE PURPOSE OF THIS FIRST UNIT IS TO DEVELOP AN UNDERSTANDING OF COMPONENTS, OPERATION, AND ADJUSTMENTS…

  7. Student Understanding of Time Dependence in Quantum Mechanics

    Science.gov (United States)

    Emigh, Paul J.; Passante, Gina; Shaffer, Peter S.

    2015-01-01

    The time evolution of quantum states is arguably one of the more difficult ideas in quantum mechanics. In this article, we report on results from an investigation of student understanding of this topic after lecture instruction. We demonstrate specific problems that students have in applying time dependence to quantum systems and in recognizing…

  8. Advances in the understanding of crystal growth mechanisms

    CERN Document Server

    Nishinaga, T; Harada, J; Sasaki, A; Takei, H

    1997-01-01

    This book contains the results of a research project entitled Crystal Growth Mechanisms on an Atomic Scale, which was carried out for 3 years by some 72 reseachers. Until recently in Japan, only the technological aspects of crystal growth have been emphasized and attention was paid only to its importance in industry. However the scientific aspects also need to be considered so that the technology of crystal growth can be developed even further. This project therefore aimed at understanding crystal growth and the emphasis was on finding growth mechanisms on an atomic scale.

  9. Raman spectroscopy as a tool to understand Kerogen production potential

    Science.gov (United States)

    Khatibi, S.; Ostadhassan, M.; Mohammed, R. A.; Alexeyev, A.

    2017-12-01

    A lot attention has given to unconventional reservoirs specifically oil shale in North America during the last decades. Understanding Kerogen properties in terms of maturity and production potential are crucial for unconventional reservoir. Since, the amount of hydrocarbon generation is a function of kerogen type and content in the formation, and the magnitude and duration in which heat and pressure were applied. This study presents a non-destructive and fast method to determine Kerogen properties in terms of Rock-Eval parameters by means of Raman Spectroscopy. Samples were gathered from upper and lower Bakken formation, with different maturities at different depth. Raman spectroscopy as a powerful nondestructive analytical tool for molecular reconstruction was employed to find Raman spectra of different samples. In the next step, Rock-Eval was performed for each sample and different measurements were made. Then in an original approach, correlation between Rock-Eval parameters with Raman Spectroscopy results was established to fully understand how kerogen productivity potentials can be reflected on the Raman response. Results showed, maturity related parameters (RO, Tmax), S1 (already generated oil in the rock), S2 (potential hydrocarbon) and OSI (oil saturation index as indication of potential oil flow zones) can be correlated to band separation, D band intensity, G band intensity and G/D intensity, respectively. Proposed method provide a fast nondestructive method to evaluate Kerogen quality even at field without any special sample preparation.

  10. Zinc diethyldithiocarbamate allergenicity: potential haptenation mechanisms.

    Science.gov (United States)

    Chipinda, Itai; Hettick, Justin M; Simoyi, Reuben H; Siegel, Paul D

    2008-08-01

    Zinc diethyldithiocarbamate (ZDEC) and its disulfide, tetraethylthiuram disulfide (TETD), are rubber accelerators and contact allergens that cross-react in some individuals. This study explored potential protein haptenation mechanisms of ZDEC and its oxidation products. ZDEC oxidation/reduction products and sites of protein binding were assessed using high-performance liquid chromatography and mass spectrometry. The murine local lymph node assay (LLNA) was employed to probe haptenation mechanisms of ZDEC by examining its allergenicity along with its oxidation products and through elimination of oxidation and chelation mechanisms by substituting cobalt for zinc [cobalt (II) dithiocarbamate, CoDEC]. Oxidation of ZDEC by hypochlorous acid (bleach, HOCl), iodine, or hydrogen peroxide resulted in production of TETD, tetraethylthiocarbamoyl disulfide, and tetraethyldicarbamoyl disulfide (TEDCD). Albumin thiols reduced TETD with subsequent mixed disulfide formation/haptenation. ZDEC directly chelated the copper ion on the active site of the superoxide dismutase, whereas CoDEC did not bind to Cu proteins or form mixed disulfides with free thiols. ZDEC, sodium diethyldithiocarbamate, TEDCD, and TETD were all positive in the LLNA except CoDEC, which was non-allergenic. The thiol is the critical functional group in ZDEC's allergenicity, and haptenation is predominantly through chelation of metalloproteins and formation of mixed disulfides.

  11. The potential mechanisms for motor complications of Parkinson's disease

    Directory of Open Access Journals (Sweden)

    SUN Sheng-gang

    2013-08-01

    Full Text Available Parkinson's disease (PD is a common neurodegenerative disease. Dopaminergic replacement therapy is still considered as a major treatment for PD. However, long-term dopaminergic replacement therapy for PD patients is frequently associated with the development of motor complications. To date, the mechanisms underlying motor complications have not been completely understood yet. Moreover, parts of motor complications are lack of therapeutic alternatives. All these characters make this disorder difficult and challenging to manage. Increasing number of researches have been proposed in recent years for elucidating the underlying mechanisms of levodopa-related motor complications, resulting in much progression. For better understanding the management of motor complications, here we provide an overview of the current knowledge of the potential mechanisms, including the pharmacodynamic and pharmacokinetic mechanisms of levodopa and levodopa-associated neurotransmitter systems.

  12. Understanding the mechanism of nanoparticle formation in wire explosion process

    International Nuclear Information System (INIS)

    Bora, B.; Wong, C.S.; Bhuyan, H.; Lee, Y.S.; Yap, S.L.; Favre, M.

    2013-01-01

    The mechanism of nanoparticle formation by wire explosion process has been investigated by optical emission spectroscopy in Antony et al. 2010 [2] [J Quant Spectrosc Radiat Transfer 2010; 111:2509]. It was reported that the size of the nanoparticles formed in Ar ambience increases with increasing pressure, while an opposite trend was observed for the nanoparticles produced in N 2 and He ambiences. However, the physics behind this opposite trend seems unclear. In this work, we have investigated the probable mechanism behind the opposite trend in particle size with pressure of different gases and understand the mechanism of nanoparticle formation in wire explosion process. The experiment was carried out to investigate the effect of ambient gas species (Ar and N 2 ) and pressure on arc plasma formation and its corresponding effects on the characteristics of the produced nanoparticles in wire explosion process. Our results show that the arc plasma formation is probably the mechanism that may account for the opposite trend of particle size with pressure of different gases. -- Highlights: ► Cu nanoparticles have been synthesized by wire explosion technique. ► Investigate the effect of the ambient gas species and pressure. ► Arc plasma formation in wire explosion process is investigated. ► Arc plasma formation plays a crucial role in characteristic of the nanoparticles

  13. Biomechanical approaches to understanding the potentially injurious demands of gymnastic-style impact landings

    Directory of Open Access Journals (Sweden)

    Gittoes Marianne JR

    2012-01-01

    Full Text Available Abstract Gymnasts are exposed to a high incidence of impact landings due to the execution of repeated dismount performances. Biomechanical research can help inform recent discussions surrounding a proposed rule change in potentially injurious gymnastic dismounting. The review examines existing understanding of the mechanisms influencing the impact loads incurred in gymnastic-style landings achieved using biomechanical approaches. Laboratory-based and theoretical modelling research of inherent and regulatory mechanisms is appraised. The integration of the existing insights into injury prevention interventions studies is further considered in the appraisals. While laboratory-based studies have traditionally been favoured, the difficulty in controlling and isolating mechanisms of interest has partially restricted the understanding gained. An increase in the use of theoretical approaches has been evident over the past two decades, which has successfully enhanced insight into less readily modified mechanisms. For example, the important contribution of mass compositions and 'tuned' mass coupling responses to impact loading has been evidenced. While theoretical studies have advanced knowledge in impact landing mechanics, restrictions in the availability of laboratory-based input data have suppressed the benefits gained. The advantages of integrating laboratory-based and theoretical approaches in furthering scientific understanding of loading mechanisms have been recognised in the literature. Since a multi-mechanism contribution to impact loading has been evident, a deviation away from studies examining isolated mechanisms may be supported for the future. A further scientific understanding of the use of regulatory mechanisms in alleviating a performer's inherent injury predisposition may subsequently be gained and used to inform potential rule changes in gymnastics. While the use of controlled studies for providing scientific evidence for the

  14. Understanding the thermal, mechanical and electrical properties of epoxy nanocomposites

    International Nuclear Information System (INIS)

    Sarathi, R.; Sahu, R.K.; Rajeshkumar, P.

    2007-01-01

    In the present work, the electrical, mechanical and thermal properties of epoxy nanocomposite materials were studied. The electrical insulation characteristics were analyzed through short time breakdown voltage test, accelerated electrical ageing test, and by tracking test. The breakdown voltage increases with increase in nano-clay content up to 5 wt%, under AC and DC voltages. The volume resistivity, permittivity and tan(δ) of the epoxy nanocomposites were measured. The Weibull studies indicate that addition of nanoclay upto 5 wt% enhances the characteristic life of epoxy nanocomposite insulation material. The tracking test results indicate that the tracking time is high with epoxy nanocomposites as compared to pure epoxy. Ageing studies were carried out to understand the surface characteristic variation through contact angle measurement. The hydrophobicity of the insulating material was analysed through contact angle measurement. The diffusion coefficients of the material with different percentage of clay in epoxy nanocomposites were calculated. The exfoliation characteristics in epoxy nanocomposites were analyzed through wide angle X-ray diffraction (WAXD) studies. The thermal behaviour of the epoxy nanocomposites was analyzed by carrying out thermo gravimetric-differential thermal analysis (TG-DTA) studies. Heat deflection temperature of the material was measured to understand the stability of the material for intermittent temperature variation. The dynamic mechanical analysis (DMA) results indicated that storage modulus of the material increases with small amount of clay in epoxy resin. The activation energy of the material was calculated from the DMA results

  15. Potential degradation mechanisms of stylolitic limestones

    Science.gov (United States)

    Aly, Nevin; Török, Ákos; Aguilar Sanchez, Asel Maria; Wangler, Timothy

    2017-04-01

    Stylolites are irregular rough surfaces formed due to the pressure-solution process and commonly developed in carbonate stones. Stylolite formation is usually accompanied by the accumulation of insoluble residues i.e. organic matter, oxides and clays on the stylolitic surfaces. The amount and the type of these clays may play a significant role in the deterioration of the host stone. This study presents the characterization of various stylolitic limestones containing different amounts of clays and used extensively as building cladding and decorative stones in Israel and in Hungary. The first case study focuses on two lithotypes from Israel, both of them are biocalcirudite-calcarenite with high amount of bioclasts. Abundance of open stylolites filled partially with organic matter and minor amounts of clays exist in the first lithotype with cream colour. The second lithotype has grey colour and contains organic matter and pyrite dispersed throughout the stone and more concentrated within the stylolites along with clay and dolomite crystal. Both lithotypes exhibit signs of decay just after a few years of exposure. The first studied Hungarian limestone is a red Jurassic carbonate (ammonitico rosso type) that was formed in pelagic marine environment. This wackestone contains abundant pelagic microfossils. The limestone has been used from Roman period in Central Europe in Hungary, Romania and Poland. The stylolites are seen as darker bedding parallel seams containing minor amounts of clay and hematite. Small amount of clay is also found in isolated nodules. The second Hungarian lithotype is also a Jurassic limestone which contains less clay than the previous one. This yellowish-white limestone is strongly cemented and contains red intersecting stylolites that do not follow the bedding planes or stratification. The main aim of this study is to understand and evaluate the damage mechanism of different stylolitic limestones. Samples were exposed to multiple thermal and wet

  16. Understanding Neurological Disease Mechanisms in the Era of Epigenetics

    Science.gov (United States)

    Qureshi, Irfan A.; Mehler, Mark F.

    2015-01-01

    The burgeoning field of epigenetics is making a significant impact on our understanding of brain evolution, development, and function. In fact, it is now clear that epigenetic mechanisms promote seminal neurobiological processes, ranging from neural stem cell maintenance and differentiation to learning and memory. At the molecular level, epigenetic mechanisms regulate the structure and activity of the genome in response to intracellular and environmental cues, including the deployment of cell type–specific gene networks and those underlying synaptic plasticity. Pharmacological and genetic manipulation of epigenetic factors can, in turn, induce remarkable changes in neural cell identity and cognitive and behavioral phenotypes. Not surprisingly, it is also becoming apparent that epigenetics is intimately involved in neurological disease pathogenesis. Herein, we highlight emerging paradigms for linking epigenetic machinery and processes with neurological disease states, including how (1) mutations in genes encoding epigenetic factors cause disease, (2) genetic variation in genes encoding epigenetic factors modify disease risk, (3) abnormalities in epigenetic factor expression, localization, or function are involved in disease pathophysiology, (4) epigenetic mechanisms regulate disease-associated genomic loci, gene products, and cellular pathways, and (5) differential epigenetic profiles are present in patient-derived central and peripheral tissues. PMID:23571666

  17. Advances in understanding Giardia: determinants and mechanisms of chronic sequelae

    Science.gov (United States)

    Sartor, R. Balfour

    2015-01-01

    Giardia lamblia is a flagellated protozoan that is the most common cause of intestinal parasitic infection in children living in resource-limited settings. The pathogenicity of Giardia has been debated since the parasite was first identified, and clinical outcomes vary across studies. Among recent perplexing findings are diametrically opposed associations between Giardia and acute versus persistent diarrhea and a poorly understood potential for long-term sequelae, including impaired child growth and cognitive development. The mechanisms driving these protean clinical outcomes remain elusive, but recent advances suggest that variability in Giardia strains, host nutritional status, the composition of microbiota, co-infecting enteropathogens, host genetically determined mucosal immune responses, and immune modulation by Giardia are all relevant factors influencing disease manifestations after Giardia infection. PMID:26097735

  18. Bronchopulmonary dysplasia: understanding of the underlying pathological mechanisms

    Directory of Open Access Journals (Sweden)

    Daniela Fanni

    2014-06-01

    Full Text Available Bronchopulmonary dysplasia (BPD is a chronic lung disease occurring in preterm infants, typically before 28 weeks of gestational age, characterized by a prolonged need for supplemental oxygen or positive pressure ventilation. The normal stages of lung development and their relation to the timing of preterm birth is strategic in order to understand the pathogenesis of BPD. In embryonic and pseudoglandular stages the lungs arise from the anterior foregut as a bud where the branching morphogenesis generate a tree-like network of airways. The canalicular stage is characterized by increasing proliferation of distal lung epithelial cells and rapid expansion of the intra-acinar capillaries. The complexity of the airways increases, secondary crests begin to form and full maturation of the alveolus occurs during the saccular and the alveolar stages. Mesechyme components, expecially elastin and myofibroblast, display a major role in normal lung development. BPD is thought to result after an acute insult to the neonatal lung following therapy with oxygen supplementation and mechanical ventilation. Chorioamnionitis, infections and genetic susceptibly are hypothesized to contribute to the injury that affect the normal human lung development. Abnormalities in the mesenchyme were consistently seen in association with inhibition of alveolarization. The pathological features that characterize BPD are complex and differ according with the disease progression. Alveolar simplification, interstitial fibrosis, septal thickness, large airways, smooth muscle hypertrophy, fetal artery persistance and decrease in the arterial number can be histologically observed. In conclusion, in order to reach a complete clinical-pathological diagnosis, the correlation of the pathological features with the fundamental steps of lung morphogenesis and a strict dialogue between the neonatologist and the perinatal pathologist are required. Given these conditions, in our experience, a

  19. Homocysteine, alcoholism and its potential epigenetic mechanism

    Science.gov (United States)

    Kamat, Pradip K.; Mallonee, Carissa J.; George, Akash K.; Tyagi, Suresh C.; Tyagi, Neetu

    2016-01-01

    Alcohol is the most socially accepted addictive drug. Alcohol consumption is associated with some health problems such as neurological, cognitive, behavioral deficits, cancer, heart and liver disease. Mechanisms of alcohol-induced toxicity are presently not yet clear. One of the mechanisms underlying alcohol toxicity has to do with its interaction with amino acid-homocysteine (Hcy), which has been linked with brain neurotoxicity. Elevated homocysteine (Hcy) impairs with various physiological mechanisms in the body, especially metabolic pathways. Hcy metabolism is predominantly controlled by epigenetic regulation such as DNA methylation, histone modifications, and acetylation. An alteration in these processes leads to epigenetic modification. Therefore, in this review, we summarize the role of Hcy metabolism abnormalities in alcohol-induced toxicity with epigenetic adaptation and their influences on cerebrovascular pathology. PMID:27805256

  20. Understanding sleep-wake mechanisms and drug discovery.

    Science.gov (United States)

    Equihua-Benítez, Ana Clementina; Guzmán-Vásquez, Khalil; Drucker-Colín, René

    2017-07-01

    Although not discernible at first glance, sleep is a highly active and regulated brain state. Although we spend practically one third of our lifetimes in this stage, its importance is often taken for granted. Sleep loss can lead to disease, error and economic loss. Our understanding of how sleep is achieved has greatly advanced in recent years, and with that, the management of sleep disorders has improved. There is still room for improvement and recently many new compounds have reached clinical trials with a few being approved for commercial use. Areas covered: In this review, the authors make the case of sleep disorders as a matter of public health. The mechanisms of sleep transition are discussed emphasizing the wake and sleep promoting interaction of different brain regions. Finally, advances in pharmacotherapy are examined in the context of chronic insomnia and narcolepsy. Expert opinion: The orexinergic system is an example of a breakthrough in sleep medicine that has catalyzed drug development. Nevertheless, sleep is a topic still with many unanswered questions. That being said, the melanin-concentrating hormone system is becoming increasingly relevant and we speculate it will be the next target of sleep medication.

  1. Understanding the mechanism of base development of hydrogen silsesquioxane

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jihoon; Chao, Weilun; Liang, Xiaogan; Griedel, Brian D.; Olynick, Deirdre L

    2009-01-09

    There have been numerous studies of electron beam exposed hydrogen silsesquioxane (HSQ) development conditions in order to improve the developer contrast. For TMAH based development, improvements were made by going to higher TMAH normalities and heating the developer. Yang and Berggren showed development of electron beam exposed (HSQ) by NaOH with added Na salts (various anions) significantly improves the contrast. Here, we study the contrast and etching rates of 100 keV exposed HSQ in NaOH in the presence of LiCl, NaCl, and KCl salts and use this as a segway to understand the mechanisms governing contrast during development HSQ development. The basic mechanism of development of HSQ can be understood by comparing to etching of quartz in basic solutions. Hydroxide ions act as nucleophiles which attack silicon. When a silicon-oxygen bond of the Si-O-Si matrix is broken, Si-O{sup -} and Si-OH are formed which can reversibly react to form the original structure. When a Si-H bond is broken via reaction with hydroxide, Si-O{sup -} and H{sub 2} gas are formed. Salts can change the etching rates as a function of dose in a non-linear fashion to increase etch contrast. Figs. 1, 2, and 3 show contrast curves for HSQ developed in 0.25 N sodium hydroxide and with the addition of NaCl, LiCl and KCl salts at several concentrations. NaCl addition resulted in the highest contrast. Contrast improves with additional salt concentration while sensitivity decreases. Interestingly enough, addition of salt decreases the removal of material of NaOH alone at higher doses while increasing the rate at lower concentrations. Addition of LiCl salts improves contrast over NaOH alone. Furthermore, the sensitivity at all doses increases as the LiCl concentration increases, a salting out effect. Similar to NaCl salt behavior, the addition of KCl salts, improves contrast at the expense of sensitivity. However, unlike NaCl, even at very high doses, KCl addition increases removal rate of HSQ. We

  2. Potential Mechanisms of Exercise in Gestational Diabetes

    Directory of Open Access Journals (Sweden)

    Saeid Golbidi

    2013-01-01

    Full Text Available Gestational diabetes mellitus (GDM is defined as glucose intolerance first diagnosed during pregnancy. This condition shares same array of underlying abnormalities as occurs in diabetes outside of pregnancy, for example, genetic and environmental causes. However, the role of a sedentary lifestyle and/or excess energy intake is more prominent in GDM. Physically active women are less likely to develop GDM and other pregnancy-related diseases. Weight gain in pregnancy causes increased release of adipokines from adipose tissue; many adipokines increase oxidative stress and insulin resistance. Increased intramyocellular lipids also increase cellular oxidative stress with subsequent generation of reactive oxygen species. A well-planned program of exercise is an important component of a healthy lifestyle and, in spite of old myths, is also recommended during pregnancy. This paper briefly reviews the role of adipokines in gestational diabetes and attempts to shed some light on the mechanisms by which exercise can be beneficial as an adjuvant therapy in GDM. In this regard, we discuss the mechanisms by which exercise increases insulin sensitivity, changes adipokine profile levels, and boosts antioxidant mechanisms.

  3. Vitamin D and Bone Health; Potential Mechanisms

    Directory of Open Access Journals (Sweden)

    J.J. Strain

    2010-07-01

    Full Text Available Osteoporosis is associated with increased morbidity, mortality and significant economic and health costs. Vitamin D is a secosteriod hormone essential for calcium absorption and bone mineralization which is positively associated with bone mineral density [BMD]. It is well-established that prolonged and severe vitamin D deficiency leads to rickets in children and osteomalacia in adults. Sub-optimal vitamin D status has been reported in many populations but it is a particular concern in older people; thus there is clearly a need for effective strategies to optimise bone health. A number of recent studies have suggested that the role of vitamin D in preventing fractures may be via its mediating effects on muscle function (a defect in muscle function is one of the classical signs of rickets and inflammation. Studies have demonstrated that vitamin D supplementation can improve muscle strength which in turn contributes to a decrease in incidence of falls, one of the largest contributors to fracture incidence. Osteoporosis is often considered to be an inflammatory condition and pro-inflammatory cytokines have been associated with increased bone metabolism. The immunoregulatory mechanisms of vitamin D may thus modulate the effect of these cytokines on bone health and subsequent fracture risk. Vitamin D, therefore, may influence fracture risk via a number of different mechanisms.

  4. Understanding the mechanisms of glutamine action in critically ill patients

    Directory of Open Access Journals (Sweden)

    Gisele P. Oliveira

    2010-06-01

    Full Text Available Glutamine (Gln is an important energy source and has been used as a supplementary energy substrate. Furthermore, Gln is an essential component for numerous metabolic functions, including acid-base homeostasis, gluconeogenesis, nitrogen transport and synthesis of proteins and nucleic acids. Therefore, glutamine plays a significant role in cell homeostasis and organ metabolism. This article aims to review the mechanisms of glutamine action during severe illnesses. In critically ill patients, the increase in mortality was associated with a decreased plasma Gln concentration. During catabolic stress, Gln consumption rate exceeds the supply, and both plasma and skeletal muscle pools of free Gln are severely reduced. The dose and route of Gln administration clearly influence its effectiveness: high-dose parenteral appears to be more beneficial than low-dose enteral administration. Experimental studies reported that Gln may protect cells, tissues, and whole organisms from stress and injury through the following mechanisms: attenuation of NF (nuclear factor-kB activation, a balance between pro- and anti-inflammatory cytokines, reduction in neutrophil accumulation, improvement in intestinal integrity and immune cell function, and enhanced of heat shock protein expression. In conclusion, high-doses of parenteral Gln (>0.50 g/kg/day demonstrate a greater potential to benefit in critically ill patients, although Gln pathophysiological mechanisms requires elucidation.A glutamina (Gln é uma importante fonte de energia e tem sido usada como substrato energético suplementar. Além disso, a Gln é um componente essencial para numerosas funções metabólicas tais como: homeostase ácido-base, gliconeogênese, transporte de nitrogênio e síntese de proteínas e ácidos nucléicos. Portanto, a glutamina desempenha um papel importante na homeostase celular e no metabolismo dos órgãos. Esse artigo objetiva rever os mecanismos de ação da glutamina na doen

  5. Potential Mechanisms of Cancer Prevention by Weight Control

    Science.gov (United States)

    Jiang, Yu; Wang, Weiqun

    Weight control via dietary caloric restriction and/or physical activity has been demonstrated in animal models for cancer prevention. However, the underlying mechanisms are not fully understood. Body weight loss due to negative energy balance significantly reduces some metabolic growth factors and endocrinal hormones such as IGF-1, leptin, and adiponectin, but enhances glucocorticoids, that may be associated with anti-cancer mechanisms. In this review, we summarized the recent studies related to weight control and growth factors. The potential molecular targets focused on those growth factors- and hormones-dependent cellular signaling pathways are further discussed. It appears that multiple factors and multiple signaling cascades, especially for Ras-MAPK-proliferation and PI3K-Akt-anti-apoptosis, could be involved in response to weight change by dietary calorie restriction and/or exercise training. Considering prevalence of obesity or overweight that becomes apparent over the world, understanding the underlying mechanisms among weight control, endocrine change and cancer risk is critically important. Future studies using "-omics" technologies will be warrant for a broader and deeper mechanistic information regarding cancer prevention by weight control.

  6. The potential for using visual elicitation in understanding preschool ...

    African Journals Online (AJOL)

    We explore the use of video and photo elicitation in a research study undertaken to understand the way in which preschool teachers perceive and construct their provision of children's educational experiences. We explore the value of visually elicited interviews based on video footage and photographs captured during ...

  7. Drama's Potential for Deepening Young Children's Understandings of Stories

    Science.gov (United States)

    Adomat, Donna Sayers

    2012-01-01

    The benefits of drama have been reported extensively in educational research literature; however, few studies provide an in-depth analysis of how drama is used in early childhood classroom instruction for readers who struggle with comprehension. The focus of this study is: How do young children build literary understanding through drama? This…

  8. Understanding human action: integrating meanings, mechanisms, causes, and contexts

    NARCIS (Netherlands)

    Keestra, M.; Repko, A.F.; Newell, W.H.; Szostak, R.

    2012-01-01

    Humans are capable of understanding an incredible variety of actions performed by other humans. Even though these range from primary biological actions like eating and fleeing, to acts in parliament or in poetry, humans generally can make sense of each other’s actions. Understanding other people’s

  9. Dyslipidemia in Obesity: Mechanisms and Potential Targets

    Directory of Open Access Journals (Sweden)

    Jan Willem F. Elte

    2013-04-01

    Full Text Available Obesity has become a major worldwide health problem. In every single country in the world, the incidence of obesity is rising continuously and therefore, the associated morbidity, mortality and both medical and economical costs are expected to increase as well. The majority of these complications are related to co-morbid conditions that include coronary artery disease, hypertension, type 2 diabetes mellitus, respiratory disorders and dyslipidemia. Obesity increases cardiovascular risk through risk factors such as increased fasting plasma triglycerides, high LDL cholesterol, low HDL cholesterol, elevated blood glucose and insulin levels and high blood pressure. Novel lipid dependent, metabolic risk factors associated to obesity are the presence of the small dense LDL phenotype, postprandial hyperlipidemia with accumulation of atherogenic remnants and hepatic overproduction of apoB containing lipoproteins. All these lipid abnormalities are typical features of the metabolic syndrome and may be associated to a pro-inflammatory gradient which in part may originate in the adipose tissue itself and directly affect the endothelium. An important link between obesity, the metabolic syndrome and dyslipidemia, seems to be the development of insulin resistance in peripheral tissues leading to an enhanced hepatic flux of fatty acids from dietary sources, intravascular lipolysis and from adipose tissue resistant to the antilipolytic effects of insulin. The current review will focus on these aspects of lipid metabolism in obesity and potential interventions to treat the obesity related dyslipidemia.

  10. Understanding the mechanism of catalytic fast pyrolysis by unveiling reactive intermediates in heterogeneous catalysis

    Science.gov (United States)

    Hemberger, Patrick; Custodis, Victoria B. F.; Bodi, Andras; Gerber, Thomas; van Bokhoven, Jeroen A.

    2017-06-01

    Catalytic fast pyrolysis is a promising way to convert lignin into fine chemicals and fuels, but current approaches lack selectivity and yield unsatisfactory conversion. Understanding the pyrolysis reaction mechanism at the molecular level may help to make this sustainable process more economic. Reactive intermediates are responsible for product branching and hold the key to unveiling these mechanisms, but are notoriously difficult to detect isomer-selectively. Here, we investigate the catalytic pyrolysis of guaiacol, a lignin model compound, using photoelectron photoion coincidence spectroscopy with synchrotron radiation, which allows for isomer-selective detection of reactive intermediates. In combination with ambient pressure pyrolysis, we identify fulvenone as the central reactive intermediate, generated by catalytic demethylation to catechol and subsequent dehydration. The fulvenone ketene is responsible for the phenol formation. This technique may open unique opportunities for isomer-resolved probing in catalysis, and holds the potential for achieving a mechanistic understanding of complex, real-life catalytic processes.

  11. Understanding the mechanism of catalytic fast pyrolysis by unveiling reactive intermediates in heterogeneous catalysis

    Science.gov (United States)

    Hemberger, Patrick; Custodis, Victoria B. F.; Bodi, Andras; Gerber, Thomas; van Bokhoven, Jeroen A.

    2017-01-01

    Catalytic fast pyrolysis is a promising way to convert lignin into fine chemicals and fuels, but current approaches lack selectivity and yield unsatisfactory conversion. Understanding the pyrolysis reaction mechanism at the molecular level may help to make this sustainable process more economic. Reactive intermediates are responsible for product branching and hold the key to unveiling these mechanisms, but are notoriously difficult to detect isomer-selectively. Here, we investigate the catalytic pyrolysis of guaiacol, a lignin model compound, using photoelectron photoion coincidence spectroscopy with synchrotron radiation, which allows for isomer-selective detection of reactive intermediates. In combination with ambient pressure pyrolysis, we identify fulvenone as the central reactive intermediate, generated by catalytic demethylation to catechol and subsequent dehydration. The fulvenone ketene is responsible for the phenol formation. This technique may open unique opportunities for isomer-resolved probing in catalysis, and holds the potential for achieving a mechanistic understanding of complex, real-life catalytic processes. PMID:28660882

  12. Unit Mechanisms of Fission Gas Release: Current Understanding and Future Needs

    Energy Technology Data Exchange (ETDEWEB)

    Tonks, Michael; Andersson , David; Devanathan, Ram; Dubourg, Roland; El-Azab, Anter A.; Freyss, Michel; Iglesias, Fernando; Kulacsy, Katalin; Pastore, Giovanni; Phillpot, Simon R.; Welland, Michael

    2018-03-16

    Gaseous fission product transport and release has a large impact on fuel performance, degrading fuel properties and, once the gas is released into the gap between the fuel and cladding, lowering gap thermal conductivity and increasing gap pressure. While gaseous fission product behavior has been investigated with bulk reactor experiments and simplified analytical models, recent improvements in experimental and modeling approaches at the atomistic and mesoscales are being applied to provide unprecedented understanding of the unit mechanisms that define the fission product behavior. In this article, existing research on the basic mechanisms behind the various stages of fission gas release during normal reactor operation are summarized and critical areas where experimental and simulation work is needed are identified. This basic understanding of the fission gas behavior mechanisms has the potential to revolutionize our ability to predict fission product behavior during reactor operation and to design fuels that have improved fission product retention. In addition, this work can serve as a model on how a coupled experimental and modeling approach can be applied to understand the unit mechanisms behind other critical behaviors in reactor materials.

  13. Understanding the mechanism of base development of HSQ

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jihoon; Chao, Weilun; Griedel, Brian; Liang, Xiaogan; Lewis, Mark; Hilken, Dawn; Olynick, Deirdre

    2009-06-16

    We study the dissolution mechanism of HSQ (hydrogen silsesquioxane) in base solutions with the addition of chloride salts to elucidate the development mechanism. Reaction mechanisms are proposed based on the dissolution mechanism of quartz. Development kinetics points to two dose-dependent development mechanisms. Considering ion sizes, both hydrated and non-hydrated, and ion exchange, we propose that a combination of a surface dominated reaction at higher doses and a matrix dominated reaction at lower doses accounts for the high development contrast with a NaOH base/NaCl salt mixture. The interplay between the hydrated and non-hydrated ion size leads to higher contrast developers, such as tetramethyl ammonium hydroxide (TMAH) with NaCl.

  14. When Christianity and homosexuality collide: understanding the potential intrapersonal conflict.

    Science.gov (United States)

    Subhi, Nasrudin; Geelan, David

    2012-01-01

    Reconciling sexual orientation with religious and spiritual beliefs can be challenging for Christian homosexuals, since many Christian churches teach that homosexual behavior is sinful. A qualitative study of 10 male and 10 female Christian homosexuals was conducted via semistructured interviews. This article seeks to explore the potential conflict between Christianity and homosexuality faced by the respondents. Participants' life stories and experiences varied widely. A few respondents were unaffected by the potential conflict between Christianity and homosexuality, however, the majority were affected. Effects included depression, guilt, anxiety, suicidal ideation, and alienation. Implications of the findings for support personnel are included.

  15. Understanding Innovative Potential (IP) in an ICT Context

    DEFF Research Database (Denmark)

    Rai, Sudhanshu

    Abstract; in this paper I discuss innovative potential at a firm level using information system literature and broadening my review to R&D literature as well. This review enables me to develop a theoretical frame of what researchers have indicated to be innovative potential or capacity at the fir...... to consider IP as a long term investment not only in human capital but in the way the human capital is allowed to engage with new ideas. I suggest IP can be build using institutional logics that enable openness and collegiality....

  16. Understanding Innovative Potential (IP) in an ICT Context

    DEFF Research Database (Denmark)

    Rai, Sudhanshu

    Abstract; in this paper I discuss innovative potential at a firm level using information system literature and broadening my review to R&D literature as well. This review enables me to develop a theoretical frame of what researchers have indicated to be innovative potential or capacity at the firm...... to consider IP as a long term investment not only in human capital but in the way the human capital is allowed to engage with new ideas. I suggest IP can be build using institutional logics that enable openness and collegiality....

  17. The Nobel Prize for understanding autophagy, a cellular mechanism ...

    Indian Academy of Sciences (India)

    The Nobel Prize in Physiology or Medicine, 2016, was awarded to Prof Yoshinori Ohsumi from TokyoInstitute of Technology, Yokohoma, Japan, for his work that helped in understanding the molecularmechanisms of autophagy, a process used by most eukaryotic cells to degrade a portion of cytoplasmincluding damaged ...

  18. Applying inversion techniques to understanding nucleus-nucleus potentials

    International Nuclear Information System (INIS)

    Mackintosh, R.S.; Cooper, S.G.

    1996-01-01

    The iterative-perturbative (IP) inversion algorithm makes it possible to determine, essentially uniquely, the complex potential, including spin-orbit component, for spin half particles given the elastic scattering S-matrix S lj . We here report an extension of the method to the determination of energy dependent potentials V(r,E) defined over an energy range for which S lj (E) are provided. This is a natural development of the IP algorithm which has previously been applied to fixed energy, fixed partial wave and the intermediate mixed case inversion. The energy range can include negative energies i.e. V(r,E) can reproduce bound state energies. It can also fit the effective range parameter for low energy scattering. We briefly define the classes of cases which can be studied, outline the IP method itself and briefly review the range of applications. We show the power of the method by presenting nucleon-αV(r,E) for S lj (E) derived from experiments above and below the inelastic threshold and relating them to V(r,E) inverted from S lj (E) for RGM theory. Reference is given to the code IMAGO which embodies the IP algorithm. (author). 38 refs., 5 figs., 4 tabs

  19. Nanoparticles and potential neurotoxicity: focus on molecular mechanisms

    Directory of Open Access Journals (Sweden)

    Davide Lovisolo

    2018-01-01

    Full Text Available The last decades have seen an explosive increase in the development of nanoparticles and in their use in consumer, industrial and medical applications. Their fast diffusion has also raised widespread concern about the potential toxic effects on living organisms, including humans: at the nanoscale, they can interact with subcellular components such as membranes, proteins, lipids, nucleic acids, thus inducing unpredicted functional perturbations in cells and tissues. The nervous tissue is a particular sensitive target, because its cellular components (mainly neurons and glial cells are tightly regulated and metabolically exigent biological entities. While the literature on the potential toxicity of nanoparticles has grown in parallel with their utilization, the available data on neurotoxicity are less abundant. In particular, information on the neuronal molecular targets of nanoparticles is still largely incomplete. A better understanding of this issue is highly relevant for the rational and controlled design of nanoparticles, both for their general utilization and more specifically for their use in the promising field of nanoneuromedicine. In this review, we will discuss the available information on the mechanisms involved in the interaction between nanoobjects and cells of the nervous system, focusing on the known molecular actors, both at the plasma membrane and in intracellular compartments.

  20. Understanding "Understanding" Flow for Network-Centric Warfare: Military Knowledge-Flow Mechanics

    National Research Council Canada - National Science Library

    Nissen, Mark

    2002-01-01

    Network-centric warfare (NCW) emphasizes information superiority for battlespace efficacy, but it is clear that the mechanics of how knowledge flows are just as important as those pertaining to the networks and communication...

  1. Understanding the Role and Mechanism of Metformin in Obesity ...

    African Journals Online (AJOL)

    Metformin, a biguanide, is a widely used drug for the treatment of type 2 diabetes mellitus. The drug also found to be beneficial in other class of diseases like obesity but its role and mechanism of action in obesity is still not well established. A literature survey was done in order to evaluate the evidence supporting metformin ...

  2. Understanding the Mechanism behind Maternal Imprisonment and Adolescent School Dropout

    Science.gov (United States)

    Cho, Rosa M.

    2011-01-01

    This study empirically tested 3 mechanisms commonly suggested to disadvantage youths whose mothers are incarcerated in prison. An event history analysis of school dropout was conducted on a sample of 6,008 adolescents in a large city created by merging several Illinois state administrative data. Findings revealed that adolescents are indeed at…

  3. Understanding the biological mechanisms of Zika virus disease ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    This project will use advanced biomolecular, genomics and proteomics techniques to explain the molecular mechanisms by which the Zika virus infects and persists in the human body, how it affects the human reproductive and central nervous system, and how the risk of fetal abnormalities can be better predicted in infected ...

  4. How Electroconvulsive Therapy Works?: Understanding the Neurobiological Mechanisms

    Science.gov (United States)

    Singh, Amit; Kar, Sujita Kumar

    2017-01-01

    Electroconvulsive therapy (ECT) is a time tested treatment modality for the management of various psychiatric disorders. There have been a lot of modifications in the techniques of delivering ECT over decades. Despite lots of criticisms encountered, ECT has still been used commonly in clinical practice due to its safety and efficacy. Research evidences found multiple neuro-biological mechanisms for the therapeutic effect of ECT. ECT brings about various neuro-physiological as well as neuro-chemical changes in the macro- and micro-environment of the brain. Diverse changes involving expression of genes, functional connectivity, neurochemicals, permeability of blood-brain-barrier, alteration in immune system has been suggested to be responsible for the therapeutic effects of ECT. This article reviews different neurobiological mechanisms responsible for the therapeutic efficacy of ECT. PMID:28783929

  5. Understanding usage patterns of electric kettle and energy saving potential

    International Nuclear Information System (INIS)

    Murray, D.M.; Liao, J.; Stankovic, L.; Stankovic, V.

    2016-01-01

    Highlights: • Time-of-use analysis to motivate kettle usage and consumption prediction. • Identification of households whose kettle usage and consumption is outside the norm. • Mathematical model to estimate water volume from consumed power measurements only. • Quantification of energy savings if a household uses its kettle more efficiently. • Kettle usage and demand prediction using an Adaptive Neuro Fuzzy Inference System. - Abstract: The availability of smart metering and smart appliances enables detecting and characterising appliance use in a household, quantifying energy savings through efficient appliance use and predicting appliance-specific demand from load measurements is possible. With growing electric kettle ownership and usage, lack of any efficiency labelling guidelines for the kettle, slow technological progress in improving kettle efficiency relative to other domestic appliances, and current consumer attitudes, urgent investigation into consumer kettle usage patterns is warranted. From an efficiency point of view, little can be done about the kettle, which is more efficient than other methods of heating water such as the stove top kettle. However, since a majority households use the kettle inefficiently by overfilling, in order to meet energy targets, it is imperative to quantify inefficient usage and predict demand. For the purposes of scalability, we propose tools that depend only on load measurement data for quantifying and visualising kettle usage and energy consumption, assessing energy wastage through overfilling via our proposed electric kettle model, and predicting kettle-specific demand, from which we can estimate potential energy savings in a household and across a housing stock. This is demonstrated using data from a longitudinal study across a sample of 14 UK households for a two-year period.

  6. Students' Conceptual Difficulties in Quantum Mechanics: Potential Well Problems

    Science.gov (United States)

    Ozcan, Ozgur; Didis, Nilufer; Tasar, Mehmet Fatih

    2009-01-01

    In this study, students' conceptual difficulties about some basic concepts in quantum mechanics like one-dimensional potential well problems and probability density of tunneling particles were identified. For this aim, a multiple choice instrument named Quantum Mechanics Conceptual Test has been developed by one of the researchers of this study…

  7. Understanding cellular responses to toxic agents: a model for mechanism-choice in bacterial metal resistance.

    Science.gov (United States)

    Rouch, D A; Lee, B T; Morby, A P

    1995-02-01

    Bacterial resistances to metals are heterogeneous in both their genetic and biochemical bases. Metal resistance may be chromosomally-, plasmid- or transposon-encoded, and one or more genes may be involved: at the biochemical level at least six different mechanisms are responsible for resistance. Various types of resistance mechanisms can occur singly or in combination and for a particular metal different mechanisms of resistance can occur in the same species. To understand better the diverse responses of bacteria to metal ion challenge we have constructed a qualitative model for the selection of metal resistance in bacteria. How a bacterium becomes resistant to a particular metal depends on the number and location of cellular components sensitive to the specific metal ion. Other important selective factors include the nature of the uptake systems for the metal, the role and interactions of the metal in the normal metabolism of the cell and the availability of plasmid (or transposon) encoded resistance mechanisms. The selection model presented is based on the interaction of these factors and allows predictions to be made about the evolution of metal resistance in bacterial populations. It also allows prediction of the genetic basis and of mechanisms of resistance which are in substantial agreement with those in well-documented populations. The interaction of, and selection for resistance to, toxic substances in addition to metals, such as antibiotics and toxic analogues, involve similar principles to those concerning metals. Potentially, models for selection of resistance to any substance can be derived using this approach.

  8. Understanding mechanisms of autoimmunity through translational research in vitiligo

    Science.gov (United States)

    Strassner, James P; Harris, John E

    2016-01-01

    Vitiligo is an autoimmune disease of the skin that leads to life-altering depigmentation and remains difficult to treat. However, clinical observations and translational studies over 30-40 years have led to the development of an insightful working model of disease pathogenesis: Genetic risk spanning both immune and melanocyte functions is pushed over a threshold by known and suspected environmental factors to initiate autoimmune T cell-mediated killing of melanocytes. While under cellular stress, melanocytes appear to signal innate immunity to activate T cells. Once the autoimmune T cell response is established, the IFN-γ-STAT1-CXCL10 signaling axis becomes the primary inflammatory pathway driving both progression and maintenance of vitiligo. This pathway is a tempting target for both existing and developing pharmaceuticals, but further detailing how melanocytes signal their own demise may also lead to new therapeutic targets. Research in vitiligo may be the future key to understand the pathogenesis of organ-specific autoimmunity, as vitiligo is common, reversible, progresses over the life of the individual, has been relatively well-defined, and is quite easy to study using translational and clinical approaches. What is revealed in these studies can lead to innovative treatments and also help elucidate the principles that underlie similar organ-specific autoimmune diseases, especially in cases where the target organ is less accessible. PMID:27764715

  9. Understanding the kinetic mechanism of RNA single base pair formation.

    Science.gov (United States)

    Xu, Xiaojun; Yu, Tao; Chen, Shi-Jie

    2016-01-05

    RNA functions are intrinsically tied to folding kinetics. The most elementary step in RNA folding is the closing and opening of a base pair. Understanding this elementary rate process is the basis for RNA folding kinetics studies. Previous studies mostly focused on the unfolding of base pairs. Here, based on a hybrid approach, we investigate the folding process at level of single base pairing/stacking. The study, which integrates molecular dynamics simulation, kinetic Monte Carlo simulation, and master equation methods, uncovers two alternative dominant pathways: Starting from the unfolded state, the nucleotide backbone first folds to the native conformation, followed by subsequent adjustment of the base conformation. During the base conformational rearrangement, the backbone either retains the native conformation or switches to nonnative conformations in order to lower the kinetic barrier for base rearrangement. The method enables quantification of kinetic partitioning among the different pathways. Moreover, the simulation reveals several intriguing ion binding/dissociation signatures for the conformational changes. Our approach may be useful for developing a base pair opening/closing rate model.

  10. Mechanisms Mediating Pediatric Severe Asthma and Potential Novel Therapies

    Directory of Open Access Journals (Sweden)

    Aldara Martin Alonso

    2017-07-01

    Full Text Available Although a rare disease, severe therapy-resistant asthma in children is a cause of significant morbidity and results in utilization of approximately 50% of health-care resources for asthma. Improving control for children with severe asthma is, therefore, an urgent unmet clinical need. As a group, children with severe asthma have severe and multiple allergies, steroid resistant airway eosinophilia, and significant structural changes of the airway wall (airway remodeling. Omalizumab is currently the only add-on therapy that is licensed for use in children with severe asthma. However, limitations of its use include ineligibility for approximately one-third of patients because of serum IgE levels outside the recommended range and lack of clinical efficacy in a further one-third. Pediatric severe asthma is thus markedly heterogeneous, but our current understanding of the different mechanisms underpinning various phenotypes is very limited. We know that there are distinctions between the factors that drive pediatric and adult disease since pediatric disease develops in the context of a maturing immune system and during lung growth and development. This review summarizes the current data that give insight into the pathophysiology of pediatric severe asthma and will highlight potential targets for novel therapies. It is apparent that in order to identify novel treatments for pediatric severe asthma, the challenge of undertaking mechanistic studies using age appropriate experimental models and airway samples from children needs to be accepted to allow a targeted approach of personalized medicine to be achieved.

  11. Exactly Solvable Quantum Mechanical Potentials: An Alternative Approach.

    Science.gov (United States)

    Pronchik, Jeremy N.; Williams, Brian W.

    2003-01-01

    Describes an alternative approach to finding exactly solvable, one-dimensional quantum mechanical potentials. Differs from the usual approach in that instead of starting with a particular potential and seeking solutions to the related Schrodinger equations, it begins with known solutions to second-order ordinary differential equations and seeks to…

  12. Bufotenine: toward an understanding of possible psychoactive mechanisms.

    Science.gov (United States)

    McBride, M C

    2000-01-01

    A review of the neuropharmacology of the alleged hallucinogen bufotenine is presented, including recent experimental results showing activity similar to LSD and other known hallucinogens (psilocin and 5-MeO-DMT) at the purported hallucinogenic serotonin (5-HT) receptors, 5-HT2A and 5-HT2C. In addition, current reports of computer modeling of the receptors and ligand binding sites give evidence of bufotenine's ability to bind and activate these receptors. While binding and activation of the purported hallucinogenic receptors are not the full extent of the hallucinogenic signature, this evidence shows support for the rationale that the reported lack of the drug's classic hallucinogenic response in human experiments is due to poor ability to cross the blood brain barrier (BBB), not lack of activation of the appropriate brain receptors. Further evidence is reviewed that in some physiological states, some drugs with characteristics similar to bufotenine which do not normally cross the BBB, cross it and enter the brain. While direct human experimental evidence of bufotenine's hallucinogenic activity seems lacking, the above combined factors are considered, and possible explanations of bufotenine's reported psychoactivity are suggested. Additionally, updated experimental models testing the possible nature of bufotenine's hallucinogenic potential are proposed.

  13. Understanding cracking failures of coatings: A fracture mechanics approach

    Science.gov (United States)

    Kim, Sung-Ryong

    A fracture mechanics analysis of coating (paint) cracking was developed. A strain energy release rate (G(sub c)) expression due to the formation of a new crack in a coating was derived for bending and tension loadings in terms of the moduli, thicknesses, Poisson's ratios, load, residual strain, etc. Four-point bending and instrumented impact tests were used to determine the in-situ fracture toughness of coatings as functions of increasing baking (drying) time. The system used was a thin coating layer on a thick substrate layer. The substrates included steel, aluminum, polycarbonate, acrylonitrile-butadiene-styrene (ABS), and Noryl. The coatings included newly developed automotive paints. The four-point bending configuration promoted nice transversed multiple coating cracks on both steel and polymeric substrates. The crosslinked type automotive coatings on steel substrates showed big cracks without microcracks. When theoretical predictions for energy release rate were compared to experimental data for coating/steel substrate samples with multiple cracking, the agreement was good. Crosslinked type coatings on polymeric substrates showed more cracks than theory predicted and the G(sub c)'s were high. Solvent evaporation type coatings on polymeric substrates showed clean multiple cracking and the G(sub c)'s were higher than those obtained by tension analysis of tension experiments with the same substrates. All the polymeric samples showed surface embrittlement after long baking times using four-point bending tests. The most apparent surface embrittlement was observed in the acrylonitrile-butadiene-styrene (ABS) substrate system. The impact properties of coatings as a function of baking time were also investigated. These experiments were performed using an instrumented impact tester. There was a rapid decrease in G(sub c) at short baking times and convergence to a constant value at long baking times. The surface embrittlement conditions and an embrittlement toughness

  14. Understanding ozone mechanisms to alleviate ceramic membrane fouling

    Science.gov (United States)

    Chu, Irma Giovanna Llamosas

    Ceramic membranes are a strong prospect as an advanced treatment in the drinking water domain. But their high capital cost and the lack of specific research on their performance still discourage their application in this field. Thus, knowing that fouling is the main drawback experienced in filtration processes, this bench-scale study was aimed to assess the impact of an ozonation pre-treatment on the alleviation of the fouling of UF ceramic membranes. Preozonation and filtration steps were performed under two different pH and ozone doses. Chosen pH values were at the limits of natural surface waters range (6.5 and 8.5) to keep practicability. Raw water from the Thousand Isle's river at Quebec-Canada was used for the tests. The filtration setup involved an unstirred dead-end filtration cell operated at constant flux. Results showed that pre-oxidation by ozone indeed reduced the fouling degree of the membranes according to the dose applied (up to 60 and 85% for membranes 8 and 50 kDa, respectively). Direct NOM oxidation was found responsible for this effect as the presence of molecular ozone was not essential to achieve these results. In the context of this experiment, however, pH showed to be more effective than the ozonation pre-treatment to keep fouling at low levels: 70% lower at pH 6.5 than at pH 8.5 for un-ozonated waters, which was contrary to most of the literature found on the topic (Changwon, 2013; De Angelis & Fidalgo, 2013; Karnik et al., 2005; S. Lee & Kim, 2014). This behaviour results mainly from the operation mode used in the experiment, the electrical repulsions between MON molecules at basic pH that led to the accumulation of material on the feed side of the membranes (concentration polarisation) and ulterior cake formation. In addition, solution pH showed an influence in the definition of fouling mechanisms. At solution pH 6.5, which was precisely the isoelectric point of the membranes (+/-6.5), the blocking fouling mode was frequently detected

  15. Sixth-Grade Students' Progress in Understanding the Mechanisms of Global Climate Change

    Science.gov (United States)

    Visintainer, Tammie; Linn, Marcia

    2015-01-01

    Developing solutions for complex issues such as global climate change requires an understanding of the mechanisms involved. This study reports on the impact of a technology-enhanced unit designed to improve understanding of global climate change, its mechanisms, and their relationship to everyday energy use. Global Climate Change, implemented in…

  16. The Coulomb potential in quantum mechanics and related topics

    International Nuclear Information System (INIS)

    Haeringen, H. van.

    1978-01-01

    This dissertation consists of an analytic study of the Coulomb interaction in nonrelativistic quantum mechanics and some related topics. The author investigates in a number of self-contained articles various interesting and important properties of the Coulomb potential. Some of these properties are shared by other potentials which also play a role in quantum mechanics. For such related interactions a comparative study is made. The principal difficulties in the description of proton-deuteron scattering and break-up reactions, due to the Coulomb interaction, are studied by working out a simple model. The bound states are studied for the Coulomb plus Yamaguchi potential, for the symmetric shifted Coulomb potential, and for local potentials with an inverse-distance-squared asymptotic behaviour. (Auth.)

  17. Twenty-five years of progress in understanding pollination mechanisms in palms (Arecaceae)

    Science.gov (United States)

    Barfod, Anders S.; Hagen, Melanie; Borchsenius, Finn

    2011-01-01

    Background With more than 90 published studies of pollination mechanisms, the palm family is one of the better studied tropical families of angiosperms. Understanding palm–pollinator interactions has implications for tropical silviculture, agroforestry and horticulture, as well as for our understanding of palm evolution and diversification. We review the rich literature on pollination mechanisms in palms that has appeared since the last review of palm pollination studies was published 25 years ago. Scope and Conclusions Visitors to palm inflorescences are attracted by rewards such as food, shelter and oviposition sites. The interaction between the palm and its visiting fauna represents a trade-off between the services provided by the potential pollinators and the antagonistic activities of other insect visitors. Evidence suggests that beetles constitute the most important group of pollinators in palms, followed by bees and flies. Occasional pollinators include mammals (e.g. bats and marsupials) and even crabs. Comparative studies of palm–pollinator interactions in closely related palm species document transitions in floral morphology, phenology and anatomy correlated with shifts in pollination vectors. Synecological studies show that asynchronous flowering and partitioning of pollinator guilds may be important regulators of gene flow between closely related sympatric taxa and potential drivers of speciation processes. Studies of larger plant–pollinator networks point out the importance of competition for pollinators between palms and other flowering plants and document how the insect communities in tropical forest canopies probably influence the reproductive success of palms. However, published studies have a strong geographical bias towards the South American region and a taxonomic bias towards the tribe Cocoseae. Future studies should try to correct this imbalance to provide a more representative picture of pollination mechanisms and their evolutionary

  18. 1/N expansion for invariant potentials in quantum mechanics

    International Nuclear Information System (INIS)

    Avan, J.; Vega, H.J. de

    1983-01-01

    The 1/N series for a general O(N) invariant potential in quantum mechanics is analyzed in the functional integral approach. We solve the stationary-point equation (here it is a non-linear and non-local equation). The instanton solutions and their action are expressed in closed form. Potentials of different shapes are analyzed. The Kth order of the 1/N expansion for the ground state energy is obtained from the instanton solution up to order K -1 . This asymptotic formula reads in terms of quadratures of the potential. The series appears to be Borel summable for a wide class of potentials. (orig.)

  19. Survivin-T34A: molecular mechanism and therapeutic potential

    Directory of Open Access Journals (Sweden)

    Jonathan R Aspe

    2010-12-01

    Full Text Available Jonathan R Aspe, Nathan R WallCenter for Health Disparities Research and Molecular Medicine, Division of Biochemistry and Microbiology, Department of Basic Sciences, Loma Linda University, Loma Linda, CA, USAAbstract: The inhibitor of apoptosis protein survivin's threonine 34 to alanine (T34A mutation abolishes a phosphorylation site for p34(cdc2–cyclin B1, resulting in initiation of the mitochondrial apoptotic pathway in cancer cells; however, it has little known direct effects on normal cells. The possibility that targeting survivin in this way may provide a novel approach for selective cancer gene therapy has yet to be fully evaluated. Although a flurry of work was undertaken in the late 1990s and early 2000s, only minor advances on this mutant have recently taken place. We recently described that cells generated to express a stable form of the mutant protein released this survivin-T34A to the conditioned medium. When this conditioned medium was collected and deposited on naive tumor cells, conditioned medium T34A was as effective as some chemotherapeutics in the induction of tumor cell apoptosis, and when combined with other forms of genotoxic stressors potentiated their killing effects. We hope with this review to revitalize the T34A field, as there is still much that needs to be investigated. In addition to determining the therapeutic dose and the duration of drug therapy required at the disease site, a better understanding of other key factors is also important. These include knowledge of target cell populations, cell-surface receptors, changes that occur in the target tissue at the molecular and cellular level with progression of the disease, and the mechanism and site of therapeutic action.Keywords: survivin, T34A, apoptosis, proliferation, therapy

  20. Improving High School Students' Understanding of Potential Difference in Simple Electric Circuits

    Science.gov (United States)

    Liegeois, Laurent; Chasseigne, G'erard; Papin, Sophie; Mullet, Etienne

    2003-01-01

    This paper reports two studies into the understanding of the concept of potential difference in the current-potential difference-resistance context among 8th-12th graders (Study 1), and the efficiency of a learning device derived from Social Judgment Theory (Study 2). These two studies showed that: (a) when asked to infer potential difference from…

  1. Understanding and assessing potential serious adverse events: a practical approach to understanding the benefits and harm of psoriasis treatments.

    Science.gov (United States)

    Papp, Kim; Guenther, Lyn; Shear, Neil; Binder, Carin; Tan, Jerry; Lynde, Charles; Gulliver, Wayne; Stang, Paul

    2013-01-01

    Any therapeutic intervention carries with it the potential for benefit and harm. Generally, benefit is far more common than risk; however, risk aversion drives many of the treatment decisions made by patients and their physicians. To provide guidelines to help clinicians improve their understanding of causality and the interpretation of harm. A group of dermatologists involved in data safety monitoring boards, clinical trial investigators, and a clinical epidemiologist identified the need for practical advice on how to understand and explain causality and harm and combined to share their knowledge. An explanation of how data are collected and the environment that shapes the data seen by clinicians is presented. The article spans an overview of the regulatory environment that informs trial design for regulatory approval to a description of types of designs that inform safety and techniques, such as the rule of three, to provide guidance to clinicians in interpreting the data. Communicating the potential for harm to patients is critical. Placing the potential for rare and serious risks into perspective for the patient is as important as discussing the potential benefits of medication.

  2. Examples of the Potential of DNS for the Understanding of Reactive Multiphase Flows

    Directory of Open Access Journals (Sweden)

    J. Reveillon

    2011-03-01

    Full Text Available The objective of this article is to point out the ability of the multiphase flow DNS (Direct Numerical Simulation to help to understand basic physics and to interpret some experimental observations. To illustrate the DNS' potential to give access to key phenomena involved in reactive multiphase flows, several recent results obtained by the authors are summed up with a bridge to experimental results. It includes droplet dispersion, laminar spray flame instability, spray combustion regimes or acoustic modulation effect on a two-phase flow Bunsen burner. As a perspective, two-phase flow DNS auto-ignition is considered thanks to a skeletal mechanism for the n-heptane chemistry involving 29 species and 52 reactions. Results highlight evaporating droplet effects on the auto-ignition process that is generally dramatically modified by spray distribution resulting from the turbulent fluid motion. This paper shows that DNS is a powerful tool to understand the intricate coupling between the evaporating spray, the turbulent fluid motion and the detailed chemistry, inseparable in the experimental context.

  3. Mechanism Of Environmental Franchising In The Sustainable Development Potential

    OpenAIRE

    Inna Illyashenko

    2011-01-01

    Reveals the types of environmental franchising: franchise environmental goods, manufacturing, service and environmental business format. Presents the methodological principles for the formation mechanisms of environmental franchise in implementing sustainable development potential. Proved economic, legal and organizational technology contractual relations regarding environmental franchise.

  4. New Potentials for Old: The Darboux Transformation in Quantum Mechanics

    Science.gov (United States)

    Williams, Brian Wesley; Celius, Tevye C.

    2008-01-01

    The Darboux transformation in quantum mechanics is reviewed at a basic level. Examples of how this transformation leads to exactly solvable potentials related to the "particle in a box" and the harmonic oscillator are shown in detail. The connection between the Darboux transformation and some modern operator based approaches to quantum mechanics…

  5. Mesenchymal Stem Cells and Metabolic Syndrome: Current Understanding and Potential Clinical Implications

    Directory of Open Access Journals (Sweden)

    Kenichi Matsushita

    2016-01-01

    Full Text Available Metabolic syndrome is an obesity-based, complicated clinical condition that has become a global epidemic problem with a high associated risk for cardiovascular disease and mortality. Dyslipidemia, hypertension, and diabetes or glucose dysmetabolism are the major factors constituting metabolic syndrome, and these factors are interrelated and share underlying pathophysiological mechanisms. Severe obesity predisposes individuals to metabolic syndrome, and recent data suggest that mesenchymal stem cells (MSCs contribute significantly to adipocyte generation by increasing the number of adipocytes. Accordingly, an increasing number of studies have examined the potential roles of MSCs in managing obesity and metabolic syndrome. However, despite the growing bank of experimental and clinical data, the efficacy and the safety of MSCs in the clinical setting are still to be optimized. It is thus hoped that ongoing and future studies can elucidate the roles of MSCs in metabolic syndrome and lead to MSC-based therapeutic options for affected patients. This review discusses current understanding of the relationship between MSCs and metabolic syndrome and its potential implications for patient management.

  6. Understanding the Electrical Behavior of the Action Potential in Terms of Elementary Electrical Sources

    Science.gov (United States)

    Rodriguez-Falces, Javier

    2015-01-01

    A concept of major importance in human electrophysiology studies is the process by which activation of an excitable cell results in a rapid rise and fall of the electrical membrane potential, the so-called action potential. Hodgkin and Huxley proposed a model to explain the ionic mechanisms underlying the formation of action potentials. However,…

  7. Anodal sensory nerve action potentials: From physiological understanding to potential clinical applicability.

    Science.gov (United States)

    Leote, Joao; Pereira, Pedro; Cabib, Christopher; Cipullo, Federica; Valls-Sole, Josep

    2016-06-01

    Low-intensity electrical stimuli of digital nerves may generate a double peak potential (DPp), composed of a cathodal (caAP) and an anodal (anAP) potential in orthodromic recordings. We studied the effects on caAP and anAP of stimuli of variable intensity, duration, and frequency. We also applied a conditioning stimulus to study potential differences in recovery time. The anAP was obtained in 33 of 40 healthy subjects (82.5%) and 4 of 20 patients with various types of sensory neuropathies (20%). Changes in stimulus duration and intensity had reciprocal effects on the amplitude of the anAP and the caAP. There were significant differences in recovery time between caAP and anAP after a conditioning stimulus. The caAP and anAP are 2 interdependent waveforms generated by different effects of the same stimulus over axons at the verge of depolarization. Muscle Nerve 53: 897-905, 2016. © 2015 Wiley Periodicals, Inc.

  8. Understanding mechanisms of raveling to extend open graded friction course (OGFC) service life.

    Science.gov (United States)

    2016-03-01

    To understand the mechanisms of raveling in open graded friction course (OGFC) mixtures, this project was divided into experimental measurements and finite element (FE) modeling. For the experimental part, mixtures with good and poor field performanc...

  9. Understanding the mechanism(s) of mosaic trisomy 21 by using DNA polymorphism analysis

    Energy Technology Data Exchange (ETDEWEB)

    Pangalos, C.; Abazis, D.; Avramopoulos, D.; Blouin, J.L.; Antonaraksi, S.E. (Univ. of Patras Medical School (Greece)); Raoul, O.; deBlois, M.C.; Prieur, M. (Cytogenetics Laboratory, Paris (France)); Schinzel, A.A.

    1994-03-01

    In order to investigate the mechanism(s) underlying mosaicism for trisomy 21, the authors genotyped 17 families with mosaic trisomy 21 probands, using 28 PCR-detectable DNA polymorphic markers that map in the pericentromeric region and long arm of chromosome 21. The percentage of cells with trisomy 21 in the probands' blood lymphocytes was 6%-94%. There were two classes of autoradiographic results: In class I, a third allele' of lower intensity was detected in the proband's DNA for at least two chromosome 21 markers. The interpretation of this result was that the proband had inherited three chromosomes 21 after meiotic nondisjunction (NDJ) (trisomy 21 zygote) and subsequently lost one because of mitotic (somatic) error, the lost chromosome 21 being that with the lowest-intensity polymorphic allele. The parental origin and the meiotic stage of NDJ could also be determined. In class II, a third allele' was never detected. In these cases, the mosaicism probably occurred either by a postzygotic, mitotic error in anormal zygote that followed a normal meiosis (class IIA mechanism); by premeiotic, mitotic NDJ yielding an aneusomic zygote after meiosis, and subsequent mitotic loss (class IIB mechanism); or by a meiosis II error with lack of crossover in the preceding meiosis I, followed by mitotic loss after fertilization (class IIC mechanism). Among class II mechanisms, the most likely is mechanism IIA, while IIC is the least likely. There were 10 cases of class I and 7 cases of class II results. Within class I, there were nine cases with maternal meitoic errors (six meiosis I and three meiosis II errors, on the basis of pericentromeric markers) and one with paternal meiosis I error. The postzygotic loss of chromosome 21 was determined in eight maternal class I cases, and it was maternally derived in five cases and paternally derived in three; this suggests that the postzygotic loss of chromosome 21 is probably random. 28 refs., 1 fig., 2 tabs.

  10. Stress Biology and Aging Mechanisms: Toward Understanding the Deep Connection Between Adaptation to Stress and Longevity

    Science.gov (United States)

    2014-01-01

    The rate of biological aging is modulated in part by genes interacting with stressor exposures. Basic research has shown that exposure to short-term stress can strengthen cellular responses to stress (“hormetic stress”). Hormetic stress promotes longevity in part through enhanced activity of molecular chaperones and other defense mechanisms. In contrast, prolonged exposure to stress can overwhelm compensatory responses (“toxic stress”) and shorten lifespan. One key question is whether the stressors that are well understood in basic models of aging can help us understand psychological stressors and human health. The psychological stress response promotes regulatory changes important in aging (e.g., increases in stress hormones, inflammation, oxidative stress, insulin). The negative effects of severe stress are well documented in humans. Potential positive effects of acute stress (stress resistance) are less studied, especially at the cellular level. Can stress resistance slow the rate of aging in humans, as it does in model organisms? If so, how can we promote stress resistance in humans? We urge a new research agenda embracing the continuum from cellular stress to psychological stress, using basic and human research in tandem. This will require interdisciplinary novel approaches that hold much promise for understanding and intervening in human chronic disease. PMID:24833580

  11. Stress biology and aging mechanisms: toward understanding the deep connection between adaptation to stress and longevity.

    Science.gov (United States)

    Epel, Elissa S; Lithgow, Gordon J

    2014-06-01

    The rate of biological aging is modulated in part by genes interacting with stressor exposures. Basic research has shown that exposure to short-term stress can strengthen cellular responses to stress ("hormetic stress"). Hormetic stress promotes longevity in part through enhanced activity of molecular chaperones and other defense mechanisms. In contrast, prolonged exposure to stress can overwhelm compensatory responses ("toxic stress") and shorten lifespan. One key question is whether the stressors that are well understood in basic models of aging can help us understand psychological stressors and human health. The psychological stress response promotes regulatory changes important in aging (e.g., increases in stress hormones, inflammation, oxidative stress, insulin). The negative effects of severe stress are well documented in humans. Potential positive effects of acute stress (stress resistance) are less studied, especially at the cellular level. Can stress resistance slow the rate of aging in humans, as it does in model organisms? If so, how can we promote stress resistance in humans? We urge a new research agenda embracing the continuum from cellular stress to psychological stress, using basic and human research in tandem. This will require interdisciplinary novel approaches that hold much promise for understanding and intervening in human chronic disease. © The Author 2014. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  12. Yogurt and Cardiometabolic Diseases: A Critical Review of Potential Mechanisms.

    Science.gov (United States)

    Fernandez, Melissa Anne; Panahi, Shirin; Daniel, Noémie; Tremblay, Angelo; Marette, André

    2017-11-01

    Associations between yogurt intake and risk of diet-related cardiometabolic diseases (CMDs) have been the subject of recent research in epidemiologic nutrition. A healthy dietary pattern has been identified as a pillar for the prevention of weight gain and CMDs. Epidemiologic studies suggest that yogurt consumption is linked to healthy dietary patterns, lifestyles, and reduced risk of CMDs, particularly type 2 diabetes. However, to our knowledge, few to no randomized controlled trials have investigated yogurt intake in relation to cardiometabolic clinical outcomes. Furthermore, there has been little attempt to clarify the mechanisms that underlie the potential beneficial effects of yogurt consumption on CMDs. Yogurt is a nutrient-dense dairy food and has been suggested to reduce weight gain and prevent CMDs by contributing to intakes of protein, calcium, bioactive lipids, and several other micronutrients. In addition, fermentation with bacterial strains generates bioactive peptides, resulting in a potentially greater beneficial effect of yogurt on metabolic health than nonfermented dairy products such as milk. To date, there is little concrete evidence that the mechanisms proposed in observational studies to explain positive results of yogurt on CMDs or parameters are valid. Many proposed mechanisms are based on assumptions that commercial yogurts contain strain-specific probiotics, that viable yogurt cultures are present in adequate quantities, and that yogurt provides a minimum threshold dose of nutrients or bioactive components capable of exerting a physiologic effect. Therefore, the primary objective of this review is to investigate the plausibility of potential mechanisms commonly cited in the literature in order to shed light on the inverse associations reported between yogurt intake and various cardiometabolic health parameters that are related to its nutrient profile, bacterial constituents, and food matrix. This article reviews current gaps and challenges

  13. Understanding the mechanisms of familiar voice-identity recognition in the human brain.

    Science.gov (United States)

    Maguinness, Corrina; Roswandowitz, Claudia; Von Kriegstein, Katharina

    2018-03-31

    Humans have a remarkable skill for voice-identity recognition: most of us can remember many voices that surround us as 'unique'. In this review, we explore the computational and neural mechanisms which may support our ability to represent and recognise a unique voice-identity. We examine the functional architecture of voice-sensitive regions in the superior temporal gyrus/sulcus, and bring together findings on how these regions may interact with each other, and additional face-sensitive regions, to support voice-identity processing. We also contrast findings from studies on neurotypicals and clinical populations which have examined the processing of familiar and unfamiliar voices. Taken together, the findings suggest that representations of familiar and unfamiliar voices might dissociate in the human brain. Such an observation does not fit well with current models for voice-identity processing, which by-and-large assume a common sequential analysis of the incoming voice signal, regardless of voice familiarity. We provide a revised audio-visual integrative model of voice-identity processing which brings together traditional and prototype models of identity processing. This revised model includes a mechanism of how voice-identity representations are established and provides a novel framework for understanding and examining the potential differences in familiar and unfamiliar voice processing in the human brain. Copyright © 2018. Published by Elsevier Ltd.

  14. Understanding the molecular mechanisms of human microtia via a pig model of HOXA1 syndrome

    Directory of Open Access Journals (Sweden)

    Ruimin Qiao

    2015-06-01

    Full Text Available Microtia is a congenital malformation of the outer ears. Although both genetic and environmental components have been implicated in microtia, the genetic causes of this innate disorder are poorly understood. Pigs have naturally occurring diseases comparable to those in humans, providing exceptional opportunity to dissect the molecular mechanism of human inherited diseases. Here we first demonstrated that a truncating mutation in HOXA1 causes a monogenic disorder of microtia in pigs. We further performed RNA sequencing (RNA-Seq analysis on affected and healthy pig embryos (day 14.25. We identified a list of 337 differentially expressed genes (DEGs between the normal and mutant samples, shedding light on the transcriptional network involving HOXA1. The DEGs are enriched in biological processes related to cardiovascular system and embryonic development, and neurological, renal and urological diseases. Aberrant expressions of many DEGs have been implicated in human innate deformities corresponding to microtia-associated syndromes. After applying three prioritizing algorithms, we highlighted appealing candidate genes for human microtia from the 337 DEGs. We searched for coding variants of functional significance within six candidate genes in 147 microtia-affected individuals. Of note, we identified one EVC2 non-synonymous mutation (p.Asp1174Asn as a potential disease-implicating variant for a human microtia-associated syndrome. The findings advance our understanding of the molecular mechanisms underlying human microtia, and provide an interesting example of the characterization of human disease-predisposing variants using pig models.

  15. Framework for Understanding the Patterns of Student Difficulties in Quantum Mechanics

    Science.gov (United States)

    Marshman, Emily; Singh, Chandralekha

    2015-01-01

    Compared with introductory physics, relatively little is known about the development of expertise in advanced physics courses, especially in the case of quantum mechanics. Here, we describe a framework for understanding the patterns of student reasoning difficulties and how students develop expertise in quantum mechanics. The framework posits that…

  16. The potential role of neuropathic mechanisms in dry eye syndromes

    Directory of Open Access Journals (Sweden)

    Charles W. Mcmonnies

    2017-01-01

    Full Text Available Dry eye syndromes can involve both nociceptive and neuropathic symptoms. Nociceptive symptoms are the normal physiological responses to noxious stimuli. Neuropathic symptoms are caused by a lesion or disease of the somatosensory nervous system and can be the result of hypersensitisation of peripheral or central corneal and conjunctival somatosensory nerves. For example, inflammation could induce neuroplastic peripheral sensitisation of the ocular surface or lid wiper and exacerbate nociceptive symptoms. Neuropathic symptoms may explain the incommensurate relation between signs and symptoms in some dry eye syndromes although absence of signs of a dry eye syndrome may also be a consequence of inappropriate methods used when examining for them. Involvement of neuropathic mechanisms may also help explain dry eye symptoms which occur in association with reduced corneal sensitivity. This review includes a discussion of the potential for ocular symptoms involving neuropathic mechanisms to contribute to psychosocial problems such as depression, stress, anxiety and sleep disorders as well as for these types of psychosocial problems to contribute to neuropathic mechanisms and dry eye syndromes. Failure to consider the possibility that neuropathic mechanisms can contribute to dry eye syndromes may reduce accuracy of diagnosis and the suitability of treatment provided. Dry eye symptoms in the absence of commensurate evidence of tear dysfunction, and unsatisfactory response to tear dysfunction therapies should prompt consideration of neuropathic mechanisms being involved. Symptoms which persist after local anaesthetic instillation are more likely to be neuropathic in origin. Reducing inflammation may help limit any associated neuroplastic hypersensitivity.

  17. Next Steps Toward Understanding Human Habitation of Space: Environmental Impacts and Mechanisms

    Science.gov (United States)

    Globus, Ruth

    2016-01-01

    Entry into low earth orbit and beyond causes profound shifts in environmental conditions that have the potential to influence human productivity, long term health, and even survival. We now have evidence that microgravity, radiation and/or confinement in space can lead to demonstrably detrimental changes in the cardiovascular (e.g. vessel function, orthostatic intolerance), musculoskeletal (muscle atrophy, bone loss) and nervous (eye, neurovestibular) systems of astronauts. Because of both the limited number of astronauts who have flown (especially females) and the high degree of individual variability in the human population, important unanswered questions about responses to the space environment remain: What are the sex differences with respect to specific physiological systems? Are the responses age-dependent and/or reversible after return to Earth? Do observed detrimental changes that resemble accelerated aging progress continuously over time or plateau? What are the mechanisms of the biological responses? Answering these important questions certainly demands a multi-pronged approach, and the study of multicellular model organisms (such as rodents and flies) already has provided opportunities for exploring those questions in some detail. Recent long duration spaceflight experiments with rodents show that mice in space provide a mammalian model that uniquely combines the influence of reduced gravitational loading with increased physical activity. In addition, multiple investigators have shown that ground-based models that simulate aspects of spaceflight (including rodent hind limb unloading to mimic weightlessness and exposure to ionizing radiation), cause various transient and persistent detrimental consequences in multiple physiological systems. In general, we have found that adverse skeletal effects of simulated weightlessness and space radiation when combined, can be quantitatively, if not qualitatively, different from the influence of each environmental

  18. Understanding Virulence in the Brucellae and Francisellae: Towards Efficacious Treatments for Two Potential Biothreat Agents

    Energy Technology Data Exchange (ETDEWEB)

    Rasley, A; Parsons, D A; El-Etr, S; Roux, C; Tsolis, R

    2009-12-30

    Francisella tularensis, Yersinia pestis and Brucellae species are highly infectious pathogens classified as select agents by the Centers for Disease Control and Prevention (CDC) with the potential for use in bioterrorism attacks. These organisms are known to be facultative intracellular pathogens that preferentially infect human monocytes. As such, understanding how the host responds to infection with these organisms is paramount in detecting and combating human disease. We have compared the ability of fully virulent strains of each pathogen and their non-pathogenic near neighbors to enter and survive inside the human monocytic cell line THP-1 and have quantified the cellular response to infection with the goal of identifying both unique and common host response patterns. We expanded the scope of these studies to include experiments with pathogenic and non-pathogenic strains of Y. pestis, the causative agent of plague. Nonpathogenic strains of each organism were impaired in their ability to survive intracellularly compared with their pathogenic counterparts. Furthermore, infection of THP-1 cells with pathogenic strains of Y. pestis and F. tularensis resulted in marked increases in the secretion of the inflammatory chemokines IL-8, RANTES, and MIP-1{beta}. In contrast, B. melitensis infection failed to elicit any significant increases in a panel of cytokines tested. These differences may underscore distinct strategies in pathogenic mechanisms employed by these pathogens.

  19. Music listening after stroke: beneficial effects and potential neural mechanisms.

    Science.gov (United States)

    Särkämö, Teppo; Soto, David

    2012-04-01

    Music is an enjoyable leisure activity that also engages many emotional, cognitive, and motor processes in the brain. Here, we will first review previous literature on the emotional and cognitive effects of music listening in healthy persons and various clinical groups. Then we will present findings about the short- and long-term effects of music listening on the recovery of cognitive function in stroke patients and the underlying neural mechanisms of these music effects. First, our results indicate that listening to pleasant music can have a short-term facilitating effect on visual awareness in patients with visual neglect, which is associated with functional coupling between emotional and attentional brain regions. Second, daily music listening can improve auditory and verbal memory, focused attention, and mood as well as induce structural gray matter changes in the early poststroke stage. The psychological and neural mechanisms potentially underlying the rehabilitating effect of music after stroke are discussed. © 2012 New York Academy of Sciences.

  20. The Potential Role of Cache Mechanism for Complicated Design Optimization

    International Nuclear Information System (INIS)

    Noriyasu, Hirokawa; Fujita, Kikuo

    2002-01-01

    This paper discusses the potential role of cache mechanism for complicated design optimization While design optimization is an application of mathematical programming techniques to engineering design problems over numerical computation, its progress has been coevolutionary. The trend in such progress indicates that more complicated applications become the next target of design optimization beyond growth of computational resources. As the progress in the past two decades had required response surface techniques, decomposition techniques, etc., any new framework must be introduced for the future of design optimization methods. This paper proposes a possibility of what we call cache mechanism for mediating the coming challenge and briefly demonstrates some promises in the idea of Voronoi diagram based cumulative approximation as an example of its implementation, development of strict robust design, extension of design optimization for product variety

  1. Conduction and scattering mechanisms in potential modulated inversion layers

    International Nuclear Information System (INIS)

    Almaggoussi, A.; Sicart, J.; Robert, J.L.; Vincent, G.

    1991-01-01

    A quantitative approach to the polycrystalline semiconductor model using an original e-beam irradiation method is proposed. The e-beam was scanned along lines parallel and perpendicular to the drain-source direction in a metal-oxide-semiconductor field-effect transistor (MOSFET) structure. Consequently, the electrostatic surface potential ψ s was periodically modulated and appeared similar to that of a polycrystalline semiconductor. The threshold voltage shift, effective and field-effect mobilities were measured as a function of both the irradiation period and dose. Conductivity and Hall effect measurements were performed between 4 and 400 K and a two-mobility conduction model is proposed to interpret the dependence of the carrier concentration and Hall mobility on temperature. Potential modulation scattering and screening mechanisms were studied by varying the gate voltage. The results are compared with those obtained in polysilicon thin layers and polysilicon MOSFETs

  2. Probiotics and Alcoholic Liver Disease: Treatment and Potential Mechanisms

    Directory of Open Access Journals (Sweden)

    Fengyuan Li

    2016-01-01

    Full Text Available Despite extensive research, alcohol remains one of the most common causes of liver disease in the United States. Alcoholic liver disease (ALD encompasses a broad spectrum of disorders, including steatosis, steatohepatitis, and cirrhosis. Although many agents and approaches have been tested in patients with ALD and in animals with experimental ALD in the past, there is still no FDA (Food and Drug Administration approved therapy for any stage of ALD. With the increasing recognition of the importance of gut microbiota in the onset and development of a variety of diseases, the potential use of probiotics in ALD is receiving increasing investigative and clinical attention. In this review, we summarize recent studies on probiotic intervention in the prevention and treatment of ALD in experimental animal models and patients. Potential mechanisms underlying the probiotic function are also discussed.

  3. Hatchery Vaccination Against Poultry Viral Diseases: Potential Mechanisms and Limitations.

    Science.gov (United States)

    Abdul-Cader, Mohamed Sarjoon; Palomino-Tapia, Victor; Amarasinghe, Aruna; Ahmed-Hassan, Hanaa; De Silva Senapathi, Upasama; Abdul-Careem, Mohamed Faizal

    Commercial broiler and layer chickens are heavily vaccinated against economically important viral diseases with a view of preventing morbidity, mortality, and production impacts encountered during short production cycles. Hatchery vaccination is performed through in ovo embryo vaccination prehatch or spray and subcutaneous vaccinations performed at the day of hatch before the day-old chickens are being placed in barns with potentially contaminated environments. Commercially, multiple vaccines (e.g., live, live attenuated, and viral vectored vaccines) are available to administer through these routes within a short period (embryo day 18 prehatch to day 1 posthatch). Although the ability to mount immune response, especially the adaptive immune response, is not optimal around the hatch, it is possible that the efficacy of these vaccines depends partly on innate host responses elicited in response to replicating vaccine viruses. This review focuses on the current knowledge of hatchery vaccination in poultry and potential mechanisms of hatchery vaccine-mediated protective responses and limitations.

  4. Understanding treatment effect mechanisms of the CAMBRA randomized trial in reducing caries increment.

    Science.gov (United States)

    Cheng, J; Chaffee, B W; Cheng, N F; Gansky, S A; Featherstone, J D B

    2015-01-01

    The Caries Management By Risk Assessment (CAMBRA) randomized controlled trial showed that an intervention featuring combined antibacterial and fluoride therapy significantly reduced bacterial load and suggested reduced caries increment in adults with 1 to 7 baseline cavitated teeth. While trial results speak to the overall effectiveness of an intervention, insight can be gained from understanding the mechanism by which an intervention acts on putative intermediate variables (mediators) to affect outcomes. This study conducted mediation analyses on 109 participants who completed the trial to understand whether the intervention reduced caries increment through its action on potential mediators (oral bacterial load, fluoride levels, and overall caries risk based on the composite of bacterial challenge and salivary fluoride) between the intervention and dental outcomes. The primary outcome was the increment from baseline in decayed, missing, and filled permanent surfaces (ΔDMFS) 24 mo after completing restorations for baseline cavitated lesions. Analyses adjusted for baseline overall risk, bacterial challenge, and fluoride values under a potential outcome framework using generalized linear models. Overall, the CAMBRA intervention was suggestive in reducing the 24-mo DMFS increment (reduction in ΔDMFS: -0.96; 95% confidence interval [CI]: -2.01 to 0.08; P = 0.07); the intervention significantly reduced the 12-mo overall risk (reduction in overall risk: -19%; 95% CI, -7 to -41%;], P = 0.005). Individual mediators, salivary log10 mutans streptococci, log10 lactobacilli, and fluoride level, did not represent statistically significant pathways alone through which the intervention effect was transmitted. However, 36% of the intervention effect on 24-mo DMFS increment was through a mediation effect on 12-mo overall risk (P = 0.03). These findings suggest a greater intervention effect carried through the combined action on multiple aspects of the caries process rather than

  5. New Drugs for Anemia Treatment Based on a New Understanding of the Mechanisms of Stress Erythropoiesis

    Science.gov (United States)

    2015-11-01

    Award Number: W81XWH-12-1-0449 TITLE: New Drugs for Anemia Treatment Based on a New Understanding of the Mechanisms of Stress Erythropoiesis...COVERED 1Sep2012 - 31Aug2015 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER New Drugs for Anemia Treatment Based on a New Understanding of the...cell formation in "Nan" (neonatal anemia ) mice, raising the level of red cells to almost normal. It also causes an increase in the numbers of splenic

  6. Towards Understanding the Catalytic Mechanism of Human Paraoxonase 1: Experimental and In Silico Mutagenesis Studies.

    Science.gov (United States)

    Tripathy, Rajan K; Aggarwal, Geetika; Bajaj, Priyanka; Kathuria, Deepika; Bharatam, Prasad V; Pande, Abhay H

    2017-08-01

    Human paraoxonase 1 (h-PON1) is a ~45-kDa serum enzyme that can hydrolyze a variety of substrates, including organophosphate (OP) compounds. It is a potential candidate for the development of antidote against OP poisoning in humans. However, insufficient OP-hydrolyzing activity of native enzyme affirms the urgent need to develop improved variant(s) having enhanced OP-hydrolyzing activity. The crystal structure of h-PON1 remains unsolved, and the molecular details of how the enzyme catalyses hydrolysis of different types of substrates are also not clear. Understanding the molecular details of the catalytic mechanism of h-PON1 is essential to engineer better variant(s) of enzyme. In this study, we have used a random mutagenesis approach to increase the OP-hydrolyzing activity of recombinant h-PON1. The mutants not only showed a 10-340-fold increased OP-hydrolyzing activity against different OP substrates but also exhibited differential lactonase and arylesterase activities. In order to investigate the mechanistic details of the effect of observed mutations on the hydrolytic activities of enzyme, molecular docking studies were performed with selected mutants. The results suggested that the observed mutations permit differential binding of substrate/inhibitor into the enzyme's active site. This may explain differential hydrolytic activities of the enzyme towards different substrates.

  7. Understanding Creep Mechanisms in Graphite with Experiments, Multiscale Simulations, and Modeling

    Energy Technology Data Exchange (ETDEWEB)

    Eapen, Jacob [North Carolina State Univ., Raleigh, NC (United States); Murty, Korukonda [North Carolina State Univ., Raleigh, NC (United States); Burchell, Timothy [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-06-02

    Disordering mechanisms in graphite have a long history with conflicting viewpoints. Using Raman and x-ray photon spectroscopy, electron microscopy, x-ray diffraction experiments and atomistic modeling and simulations, the current project has developed a fundamental understanding of early-to-late state radiation damage mechanisms in nuclear reactor grade graphite (NBG-18 and PCEA). We show that the topological defects in graphite play an important role under neutron and ion irradiation.

  8. Potential mechanisms for imperfect synchronization in parkinsonian basal ganglia.

    Directory of Open Access Journals (Sweden)

    Choongseok Park

    Full Text Available Neural activity in the brain of parkinsonian patients is characterized by the intermittently synchronized oscillatory dynamics. This imperfect synchronization, observed in the beta frequency band, is believed to be related to the hypokinetic motor symptoms of the disorder. Our study explores potential mechanisms behind this intermittent synchrony. We study the response of a bursting pallidal neuron to different patterns of synaptic input from subthalamic nucleus (STN neuron. We show how external globus pallidus (GPe neuron is sensitive to the phase of the input from the STN cell and can exhibit intermittent phase-locking with the input in the beta band. The temporal properties of this intermittent phase-locking show similarities to the intermittent synchronization observed in experiments. We also study the synchronization of GPe cells to synaptic input from the STN cell with dependence on the dopamine-modulated parameters. Earlier studies showed how the strengthening of dopamine-modulated coupling may lead to transitions from non-synchronized to partially synchronized dynamics, typical in Parkinson's disease. However, dopamine also affects the cellular properties of neurons. We show how the changes in firing patterns of STN neuron due to the lack of dopamine may lead to transition from a lower to a higher coherent state, roughly matching the synchrony levels observed in basal ganglia in normal and parkinsonian states. The intermittent nature of the neural beta band synchrony in Parkinson's disease is achieved in the model due to the interplay of the timing of STN input to pallidum and pallidal neuronal dynamics, resulting in sensitivity of pallidal output to the phase of the arriving STN input. Thus the mechanism considered here (the change in firing pattern of subthalamic neurons through the dopamine-induced change of membrane properties may be one of the potential mechanisms responsible for the generation of the intermittent synchronization

  9. Molecular mechanism and potential targets for bone metastasis

    International Nuclear Information System (INIS)

    Iguchi, Haruo

    2007-01-01

    The incidence of bone metastasis has been increasing in all cancers in recent years. Bone metastasis is associated with substantial morbidity, including bone pain, pathological fracture, neurological deficit and/or hypercalcemia. Thus, the management of bone metastasis in patients is a clinically significant issue. In the process of bone metastasis, the primary mechanism responsible for bone destruction is cancer cell-mediated stimulation of osteoclastic bone resorption, which results in osteolysis and release of various growth factors from the bone matrix. These growth factors are prerequisites for successful colonization and subsequent invasive growth of cancer cells in bone, which is called a 'vicious cycle.' Thus, it is important to elucidate what molecules are involved in this step of bone destruction, and the understanding of these molecular mechanisms could lead to develop molecular-target therapies for bone metastasis. Bisphosphonates introduced in the treatment for bone metastasis have been shown to reduce skeletal morbidity. In Japan, the most potent bisphosphonate, zoledronate (ZOMETA), was introduced in this past April, and a phase III clinical trial of humanized anti-receptor activator of NF-κB ligand (RANKL) monoclonal antibody (Denosumab) against bone metastasis is under way as a global study. These new agents, which are targeted to osteoclasts, are considered to be standard management in the care of bone metastasis patients in combination with chemotherapy and/or hormone therapy. (author)

  10. Sixth-Grade Students' Progress in Understanding the Mechanisms of Global Climate Change

    Science.gov (United States)

    Visintainer, Tammie; Linn, Marcia

    2015-04-01

    Developing solutions for complex issues such as global climate change requires an understanding of the mechanisms involved. This study reports on the impact of a technology-enhanced unit designed to improve understanding of global climate change, its mechanisms, and their relationship to everyday energy use. Global Climate Change, implemented in the Web-based Inquiry Science Environment (WISE), engages sixth-grade students in conducting virtual investigations using NetLogo models to foster an understanding of core mechanisms including the greenhouse effect. Students then test how the greenhouse effect is enhanced by everyday energy use. This study draws on three data sources: (1) pre- and post-unit interviews, (2) analysis of embedded assessments following virtual investigations, and (3) contrasting cases of two students (normative vs. non-normative understanding of the greenhouse effect). Results show the value of using virtual investigations for teaching the mechanisms associated with global climate change. Interviews document that students hold a wide range of ideas about the mechanisms driving global climate change. Investigations with models help students use evidence-based reasoning to distinguish their ideas. Results show that understanding the greenhouse effect offers a foundation for building connections between everyday energy use and increases in global temperature. An impediment to establishing coherent understanding was the persistence of an alternative conception about ozone as an explanation for climate change. These findings illustrate the need for regular revision of curriculum based on classroom trials. We discuss key design features of models and instructional revisions that can transform the teaching and learning of global climate change.

  11. Rac1 in human diseases: The therapeutic potential of targeting Rac1 signaling regulatory mechanisms.

    Science.gov (United States)

    Marei, Hadir; Malliri, Angeliki

    2017-07-03

    Abnormal Rac1 signaling is linked to a number of debilitating human diseases, including cancer, cardiovascular diseases and neurodegenerative disorders. As such, Rac1 represents an attractive therapeutic target, yet the search for effective Rac1 inhibitors is still underway. Given the adverse effects associated with Rac1 signaling perturbation, cells have evolved several mechanisms to ensure the tight regulation of Rac1 signaling. Thus, characterizing these mechanisms can provide invaluable information regarding major cellular events that lead to aberrant Rac1 signaling. Importantly, this information can be utilized to further facilitate the development of effective pharmacological modulators that can restore normal Rac1 signaling. In this review, we focus on the pathological role of Rac1 signaling, highlighting the benefits and potential drawbacks of targeting Rac1 in a clinical setting. Additionally, we provide an overview of available compounds that target key Rac1 regulatory mechanisms and discuss future therapeutic avenues arising from our understanding of these mechanisms.

  12. Models of intracellular mechanisms of plant bioelectrical potentials caused by combined stimulation

    Directory of Open Access Journals (Sweden)

    D. V. Chernetchenko

    2014-10-01

    Full Text Available This paper deals with bioelectrical potentials of the plants recorded during different types of stimuli and combined stimulus as well. All registrations were observed on the leaves of the corn. We used different stimuli, such as cold, heat, photo- and electrical stimulation, and certain combination of this stimuli. Hardware and software system for automated recording of bioelectrical potentials has been successfully used in this work. We proposed the universal pattern of bioelectrical potentials’ recording which allowed to detect the response of the biological object to different stimuli and various combinations of these stimuli. This pattern can be used for the deeper understanding of biological mechanisms of electrical potentials’ generation in cells and discovering of processes of accommodation of whole organisms to these stimuli. Integrated system of recording and biometrical processing was used for analysis of corn leaves electrical responses to the thermal stimuli. The dynamics of these potentials was studied, with the quantitative analysis of the potential level stabilization.We calculated the ratio of amplitude of response potentials to the first response amplitude. Mathematical models of the plant cell were used for studying of intracellular mechanisms of biopotentials gereration. As a result of modeling, we revealed that electrical response of the cells was based on selectiveconductivity of cell membrane for Н+ and Ca2+ ions. Therefore, we showed the biophysical relation of plant potentials to underlying intracellular biophysical mechanisms during thermal and combined stimulation.

  13. Effects of Representation Sequences and Spatial Ability on Students' Scientific Understandings about the Mechanism of Breathing

    Science.gov (United States)

    Wu, Hsin-Kai; Lin, Yu-Fen; Hsu, Ying-Shao

    2013-01-01

    The purpose of this study was to investigate the effects of representation sequences and spatial ability on students' scientific understandings about the mechanism of breathing in human beings. 130 seventh graders were assigned to two groups with different sequential combinations of static and dynamic representations: SD group (i.e., viewing…

  14. Enhanced understanding of the relationship between chemical modification and mechanical properties of wood

    Science.gov (United States)

    Charles R. Frihart; Daniel J. Yelle; John Ralph; Robert J. Moon; Donald S. Stone; Joseph E. Jakes

    2008-01-01

    Chemical additions to wood often change its bulk properties, which can be determined using conventional macroscopic mechanical tests. However, the controlling interactions between chemicals and wood take place at and below the scale of individual cells and cell walls. To better understand the effects of chemical additions to wood, we have adapted and extended two...

  15. Bee venom therapy: Potential mechanisms and therapeutic applications.

    Science.gov (United States)

    Zhang, Shuai; Liu, Yi; Ye, Yang; Wang, Xue-Rui; Lin, Li-Ting; Xiao, Ling-Yong; Zhou, Ping; Shi, Guang-Xia; Liu, Cun-Zhi

    2018-04-11

    Bee venom is a very complex mixture of natural products extracted from honey bee which contains various pharmaceutical properties such as peptides, enzymes, biologically active amines and nonpeptide components. The use of bee venom into the specific points is so called bee venom therapy, which is widely used as a complementary and alternative therapy for 3000 years. A growing number of evidence has demonstrated the anti-inflammation, the anti-apoptosis, the anti-fibrosis and the anti-arthrosclerosis effects of bee venom therapy. With these pharmaceutical characteristics, bee venom therapy has also been used as the therapeutic method in treating rheumatoid arthritis, amyotrophic lateral sclerosis, Parkinson's disease, Alzheimer's disease, liver fibrosis, atherosclerosis, pain and others. Although widely used, several cases still reported that bee venom therapy might cause some adverse effects, such as local itching or swelling. In this review, we summarize its potential mechanisms, therapeutic applications, and discuss its existing problems. Copyright © 2018 Elsevier Ltd. All rights reserved.

  16. An empirical review of potential mediators and mechanisms of prolonged exposure therapy.

    Science.gov (United States)

    Cooper, Andrew A; Clifton, Erin G; Feeny, Norah C

    2017-08-01

    Prolonged exposure (PE) is an empirically-supported treatment for posttraumatic stress disorder (PTSD), but the precise mechanism(s) by which PE promotes symptom change are not well established. Understanding how PE works is critical to improving clinical outcomes, advancing dissemination efforts, and enhancing transdiagnostic models of psychopathology. However, mechanisms research conducted in clinical treatment settings is complex, and findings may be difficult to interpret without appropriate context. This is the first review of potential mechanisms of PE to provide such context, by rigorously evaluating empirical findings in line with essential criteria for effective research on mechanisms (or mediators). We begin by describing six putative mechanisms identified by emotional processing theory and contemporary models of fear extinction, before thoroughly reviewing empirical findings from clinical research on PE and similar PTSD treatments. We provide a detailed description of each study and mechanism test, as well as ratings of strength of evidence and quality of evaluation based on a novel rating scheme. We highlight variables with strong evidence (belief change and between-session habituation), intermediate evidence (inhibitory learning and emotional engagement), and minimal support (narrative organization and within-session habituation). After discussing limitations of the extant literature and this review, we summarize specific challenges for research on PE mechanisms and highlight directions for future study based on clinical and research implications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Linking Pesticide Exposure with Pediatric Leukemia: Potential Underlying Mechanisms.

    Science.gov (United States)

    Hernández, Antonio F; Menéndez, Pablo

    2016-03-29

    Leukemia is the most common cancer in children, representing 30% of all childhood cancers. The disease arises from recurrent genetic insults that block differentiation of hematopoietic stem and/or progenitor cells (HSPCs) and drives uncontrolled proliferation and survival of the differentiation-blocked clone. Pediatric leukemia is phenotypically and genetically heterogeneous with an obscure etiology. The interaction between genetic factors and environmental agents represents a potential etiological driver. Although information is limited, the principal toxic mechanisms of potential leukemogenic agents (e.g., etoposide, benzene metabolites, bioflavonoids and some pesticides) include topoisomerase II inhibition and/or excessive generation of free radicals, which may induce DNA single- and double-strand breaks (DNA-DSBs) in early HSPCs. Chromosomal rearrangements (duplications, deletions and translocations) may occur if these lesions are not properly repaired. The initiating hit usually occurs in utero and commonly leads to the expression of oncogenic fusion proteins. Subsequent cooperating hits define the disease latency and occur after birth and may be of a genetic, epigenetic or immune nature (i.e., delayed infection-mediated immune deregulation). Here, we review the available experimental and epidemiological evidence linking pesticide exposure to infant and childhood leukemia and provide a mechanistic basis to support the association, focusing on early initiating molecular events.

  18. Potential Mechanisms and Functions of Intermittent Neural Synchronization

    Directory of Open Access Journals (Sweden)

    Sungwoo Ahn

    2017-05-01

    Full Text Available Neural synchronization is believed to play an important role in different brain functions. Synchrony in cortical and subcortical circuits is frequently variable in time and not perfect. Few long intervals of desynchronized dynamics may be functionally different from many short desynchronized intervals although the average synchrony may be the same. Recent analysis of imperfect synchrony in different neural systems reported one common feature: neural oscillations may go out of synchrony frequently, but primarily for a short time interval. This study explores potential mechanisms and functional advantages of this short desynchronizations dynamics using computational neuroscience techniques. We show that short desynchronizations are exhibited in coupled neurons if their delayed rectifier potassium current has relatively large values of the voltage-dependent activation time-constant. The delayed activation of potassium current is associated with generation of quickly-rising action potential. This “spikiness” is a very general property of neurons. This may explain why very different neural systems exhibit short desynchronization dynamics. We also show how the distribution of desynchronization durations may be independent of the synchronization strength. Finally, we show that short desynchronization dynamics requires weaker synaptic input to reach a pre-set synchrony level. Thus, this dynamics allows for efficient regulation of synchrony and may promote efficient formation of synchronous neural assemblies.

  19. Comparative epigenomics: an emerging field with breakthrough potential to understand evolution of epigenetic regulation

    Directory of Open Access Journals (Sweden)

    Janine E. Deakin

    2014-12-01

    Full Text Available Epigenetic mechanisms regulate gene expression, thereby mediating the interaction between environment, genotype and phenotype. Changes to epigenetic regulation of genes may be heritable, permitting rapid adaptation of a species to environmental cues. However, most of the current understanding of epigenetic gene regulation has been gained from studies of mice and humans, with only a limited understanding of the conservation of epigenetic mechanisms across divergent taxa. The relative ease at which genome sequence data is now obtained and the advancements made in epigenomics techniques for non-model species provides a basis for carrying out comparative epigenomic studies across a wider range of species, making it possible to start unraveling the evolution of epigenetic mechanisms. We review the current knowledge of epigenetic mechanisms obtained from studying model organisms, give an example of how comparative epigenomics using non-model species is helping to trace the evolutionary history of X chromosome inactivation in mammals and explore the opportunities to study comparative epigenomics in biological systems displaying adaptation between species, such as the immune system and sex determination.

  20. How LeuT shapes our understanding of the mechanisms of sodium-coupled neurotransmitter transporters.

    Science.gov (United States)

    Penmatsa, Aravind; Gouaux, Eric

    2014-03-01

    Neurotransmitter transporters are ion-coupled symporters that drive the uptake of neurotransmitters from neural synapses. In the past decade, the structure of a bacterial amino acid transporter, leucine transporter (LeuT), has given valuable insights into the understanding of architecture and mechanism of mammalian neurotransmitter transporters. Different conformations of LeuT, including a substrate-free state, inward-open state, and competitive and non-competitive inhibitor-bound states, have revealed a mechanistic framework for the transport and transport inhibition of neurotransmitters. The current review integrates our understanding of the mechanistic and pharmacological properties of eukaryotic neurotransmitter transporters obtained through structural snapshots of LeuT.

  1. Understanding the growth mechanism of carbon nanotubes via the ``cluster volume to surface area" model

    Science.gov (United States)

    Mandati, Sreekanth; Kunstmann, Jens; Boerrnert, Felix; Schoenfelder, Ronny; Ruemmeli, Mark; Kar, Kamal K.; Cuniberti, Gianaurelio

    2010-03-01

    The influence of mixed catalysts for the high yield production of carbon nanotubes (CNTs) has been studied systematically. Based on extensive experimental data a ``Catalyst Volume to Surface Area'' (CVSA) model was developed to understand the influence of the process parameters on the yield and CNT diameter distribution [1]. In our study, we present a refined version of the CVSA model developed by combining experiments and simulations. We discuss our current understanding of the growth mechanism and how the model might be used to increase CNT yields by using mixed catalysts.[4pt] [1] S. Tetali et al., ACS Nano (2009), DOI: 10.1021/nn9012548.

  2. Proteomic approaches to understanding the role of the cytoskeleton in host-defense mechanisms

    Science.gov (United States)

    Radulovic, Marko; Godovac-Zimmermann, Jasminka

    2014-01-01

    The cytoskeleton is a cellular scaffolding system whose functions include maintenance of cellular shape, enabling cellular migration, division, intracellular transport, signaling and membrane organization. In addition, in immune cells, the cytoskeleton is essential for phagocytosis. Following the advances in proteomics technology over the past two decades, cytoskeleton proteome analysis in resting and activated immune cells has emerged as a possible powerful approach to expand our understanding of cytoskeletal composition and function. However, so far there have only been a handful of studies of the cytoskeleton proteome in immune cells. This article considers promising proteomics strategies that could augment our understanding of the role of the cytoskeleton in host-defense mechanisms. PMID:21329431

  3. Understanding the Mechanisms of Radiation Belt Dropouts Observed by Van Allen Probes

    Science.gov (United States)

    Xiang, Zheng; Tu, Weichao; Li, Xinlin; Ni, Binbin; Morley, S. K.; Baker, D. N.

    2017-10-01

    To achieve a better understanding of the dominant loss mechanisms for the rapid dropouts of radiation belt electrons, three distinct radiation belt dropout events observed by Van Allen Probes are comprehensively investigated. For each event, observations of the pitch angle distribution of electron fluxes and electromagnetic ion cyclotron (EMIC) waves are analyzed to determine the effects of atmospheric precipitation loss due to pitch angle scattering induced by EMIC waves. Last closed drift shells (LCDS) and magnetopause standoff position are obtained to evaluate the effects of magnetopause shadowing loss. Evolution of electron phase space density (PSD) versus L* profiles and the μ and K (first and second adiabatic invariants) dependence of the electron PSD drops are calculated to further analyze the dominant loss mechanisms at different L*. Our findings suggest that these radiation belt dropouts can be classified into distinct classes in terms of dominant loss mechanisms: magnetopause shadowing dominant, EMIC wave scattering dominant, and combination of both mechanisms. Different from previous understanding, our results show that magnetopause shadowing can deplete electrons at L* 4. Compared to the magnetopause standoff position, it is more reliable to use LCDS to evaluate the impact of magnetopause shadowing. The evolution of electron PSD versus L* profile and the μ, K dependence of electron PSD drops can provide critical and credible clues regarding the mechanisms responsible for electron losses at different L* over the outer radiation belt.

  4. Canada's potential role in the Clean Development Mechanism

    International Nuclear Information System (INIS)

    Pape-Salmon, A.

    2000-01-01

    The role that Canada might play in the Kyoto Protocol's Clean Development Mechanism (CDM) is discussed. The CDM prescribes the way in which industrialized countries could create emission reduction credits for greenhouse gas emission reduction projects in developing countries which, in turn they could use to meet their own commitments and possibly reduce their cost of compliance with the Kyoto Protocol. While Canada does not see itself as a CDM project investor, it strongly supports private sector involvement in the CDM and believes that it has a role to play in assisting CDM investments by the Canadian private sector by facilitating desirable outcomes via international negotiations on the rules and modalities for the CDM which would minimize transaction costs; give prominence to aspects that Canada recognizes as necessary precursors to mobilizing private sector involvement in CDM activities; maximize the flexibility for use of the CDM; allow for conversion of credits between different Kyoto Mechanisms; allow for the certification of emissions sequestration from sinks; and maximize the environmental and sustainable development benefits of CDM projects. Canada also supports, along with the other members of the 'Umbrella group', the fewest possible restrictions and significant autonomy to the private sector to implement a variety of project activities in developing countries. This report provides a detailed examination of the Canadian government's views on the CDM, Canada's participation in international emission reduction projects, the factors that drive Canadian demand for greenhouse gas emission reduction offsets and the potential demand for CDM offsets, Canada's greenhouse gas emission inventory and projections, the approach of Canadian corporate investors in the CDM and Canadian technology and expertise in greenhouse gas emission reductions. Various appendices to the report contain further details on a number of cooperation agreements between Canada and other

  5. Unified understanding of folding and binding mechanisms of globular and intrinsically disordered proteins.

    Science.gov (United States)

    Arai, Munehito

    2018-01-06

    Extensive experimental and theoretical studies have advanced our understanding of the mechanisms of folding and binding of globular proteins, and coupled folding and binding of intrinsically disordered proteins (IDPs). The forces responsible for conformational changes and binding are common in both proteins; however, these mechanisms have been separately discussed. Here, we attempt to integrate the mechanisms of coupled folding and binding of IDPs, folding of small and multi-subdomain proteins, folding of multimeric proteins, and ligand binding of globular proteins in terms of conformational selection and induced-fit mechanisms as well as the nucleation-condensation mechanism that is intermediate between them. Accumulating evidence has shown that both the rate of conformational change and apparent rate of binding between interacting elements can determine reaction mechanisms. Coupled folding and binding of IDPs occurs mainly by induced-fit because of the slow folding in the free form, while ligand binding of globular proteins occurs mainly by conformational selection because of rapid conformational change. Protein folding can be regarded as the binding of intramolecular segments accompanied by secondary structure formation. Multi-subdomain proteins fold mainly by the induced-fit (hydrophobic collapse) mechanism, as the connection of interacting segments enhances the binding (compaction) rate. Fewer hydrophobic residues in small proteins reduce the intramolecular binding rate, resulting in the nucleation-condensation mechanism. Thus, the folding and binding of globular proteins and IDPs obey the same general principle, suggesting that the coarse-grained, statistical mechanical model of protein folding is promising for a unified theoretical description of all mechanisms.

  6. Material properties of biofilms – key methods for understanding permeability and mechanics

    Science.gov (United States)

    Billings, Nicole; Birjiniuk, Alona; Samad, Tahoura S.; Doyle, Patrick S.; Ribbeck, Katharina

    2015-01-01

    Microorganisms can form biofilms, which are multicellular communities surrounded by a hydrated extracellular matrix of polymers. Central properties of the biofilm are governed by this extracellular matrix, which provides mechanical stability to the three-dimensional biofilm structure, regulates the ability of the biofilm to adhere to surfaces, and determines the ability of the biofilm to adsorb gasses, solutes, and foreign cells. Despite their critical relevance for understanding and eliminating of biofilms, the materials properties of the extracellular matrix are understudied. Here, we offer the reader a guide to current technologies that can be utilized to specifically assess the permeability and mechanical properties of the biofilm matrix and its interacting components. In particular, we highlight technological advances in instrumentation and interactions between multiple disciplines that have broadened the spectrum of methods available to conduct these studies. We review pioneering work that furthers our understanding of the material properties of biofilms. PMID:25719969

  7. Improving student understanding of addition of angular momentum in quantum mechanics

    Directory of Open Access Journals (Sweden)

    Guangtian Zhu

    2013-01-01

    Full Text Available We describe the difficulties advanced undergraduate and graduate students have with concepts related to addition of angular momentum in quantum mechanics. We also describe the development and implementation of a research-based learning tool, Quantum Interactive Learning Tutorial (QuILT, to reduce these difficulties. The preliminary evaluation shows that the QuILT related to the basics of the addition of angular momentum is helpful in improving students’ understanding of these concepts.

  8. Understanding treatment effect mechanisms of the CAMBRA randomized trial in reducing caries increment

    OpenAIRE

    Cheng, J; Chaffee, BW; Cheng, NF; Gansky, SA; Featherstone, JDB

    2015-01-01

    © International & American Associations for Dental Research 2014. The Caries Management By Risk Assessment (CAMBRA) randomized controlled trial showed that an intervention featuring combined antibacterial and fluoride therapy significantly reduced bacterial load and suggested reduced caries increment in adults with 1 to 7 baseline cavitated teeth. While trial results speak to the overall effectiveness of an intervention, insight can be gained from understanding the mechanism by which an int...

  9. Forever Young: Mechanisms of Natural Anoxia Tolerance and Potential Links to Longevity

    Directory of Open Access Journals (Sweden)

    Anastasia Krivoruchko

    2010-01-01

    Full Text Available While mammals cannot survive oxygen deprivation for more than a few minutes without sustaining severe organ damage, some animals have mastered anaerobic life. Freshwater turtles belonging to the Trachemys and Chrysemys genera are the champion facultative anaerobes of the vertebrate world, often surviving without oxygen for many weeks at a time. The physiological and biochemical mechanisms that underlie anoxia tolerance in turtles include profound metabolic rate depression, post-translational modification of proteins, strong antioxidant defenses, activation of specific stress-responsive transcription factors, and enhanced expression of cyto-protective proteins. Turtles are also known for their incredible longevity and display characteristics of “negligible senescence.” We propose that the robust stress-tolerance mechanisms that permit long term anaerobiosis by turtles may also support the longevity of these animals. Many of the mechanisms involved in natural anoxia tolerance, such as hypometabolism or the induction of various protective proteins/pathways, have been shown to play important roles in mammalian oxygen-related diseases and improved understanding of how cells survive without oxygen could aid in the understanding and treatment of various pathological conditions that involve hypoxia or oxidative stress. In the present review we discuss the recent advances made in understanding the molecular nature of anoxia tolerance in turtles and the potential links between this tolerance and longevity.

  10. The potential biological mechanisms of arsenic-induced diabetes mellitus

    International Nuclear Information System (INIS)

    Tseng, C.-H.

    2004-01-01

    Although epidemiologic studies carried out in Taiwan, Bangladesh, and Sweden have demonstrated a diabetogenic effect of arsenic, the mechanisms remain unclear and require further investigation. This paper reviewed the potential biological mechanisms of arsenic-induced diabetes mellitus based on the current knowledge of the biochemical properties of arsenic. Arsenate can substitute phosphate in the formation of adenosine triphosphate (ATP) and other phosphate intermediates involved in glucose metabolism, which could theoretically slow down the normal metabolism of glucose, interrupt the production of energy, and interfere with the ATP-dependent insulin secretion. However, the concentration of arsenate required for such reaction is high and not physiologically relevant, and these effects may only happen in acute intoxication and may not be effective in subjects chronically exposed to low-dose arsenic. On the other hand, arsenite has high affinity for sulfhydryl groups and thus can form covalent bonds with the disulfide bridges in the molecules of insulin, insulin receptors, glucose transporters (GLUTs), and enzymes involved in glucose metabolism (e.g., pyruvate dehydrogenase and α-ketoglutarate dehydrogenase). As a result, the normal functions of these molecules can be hampered. However, a direct effect on these molecules caused by arsenite at physiologically relevant concentrations seems unlikely. Recent evidence has shown that treatment of arsenite at lower and physiologically relevant concentrations can stimulate glucose transport, in contrary to an inhibitory effect exerted by phenylarsine oxide (PAO) or by higher doses of arsenite. Induction of oxidative stress and interferences in signal transduction or gene expression by arsenic or by its methylated metabolites are the most possible causes to arsenic-induced diabetes mellitus through mechanisms of induction of insulin resistance and β cell dysfunction. Recent studies have shown that, in subjects with chronic

  11. How Do Corporate Governance Mechanisms Affect A Firm’s Potential For Bankruptcy?

    Directory of Open Access Journals (Sweden)

    Rhesa Theodorus Hanani

    2015-03-01

    Full Text Available The purpose of this thesis is to understand the effects of corporate governance mechanisms on the potential for bankruptcy. This study is done by utilizing the linear regression fixed effect vector decomposition model on 30 listed firms from the consumer goods sector of Indonesia Stock Exchange during the 2010-2012 periods. The results of the study indicate that: the board of commissioners’ independence and size of the commissioners’ board pose a significant positive effect on the potential for bankruptcy; the presence of an audit committee and the presence of a nomination and remuneration committee pose a significant negative effect and institutional ownership and managerial ownership do not significantly affect the potential for bankruptcy.

  12. Ranking mechanical pulps for their potential to photoyellow

    Science.gov (United States)

    Umesh P. Agarwal

    2000-01-01

    Recently found experimental evidence has provided strong support for an alternative photoyellowing mechanism that suggests that pulp- photoyellowing occurs due to direct photooxidation of hydroquinones (present in mechanical pulps) top-quinones. Because hydroquinones were found to be present in pulps, it may be possible to quantify them. Quantification of mechanical-...

  13. Potential Mechanisms Underlying Centralized Pain and Emerging Therapeutic Interventions

    Directory of Open Access Journals (Sweden)

    Olivia C. Eller-Smith

    2018-02-01

    Full Text Available Centralized pain syndromes are associated with changes within the central nervous system that amplify peripheral input and/or generate the perception of pain in the absence of a noxious stimulus. Examples of idiopathic functional disorders that are often categorized as centralized pain syndromes include fibromyalgia, chronic pelvic pain syndromes, migraine, and temporomandibular disorder. Patients often suffer from widespread pain, associated with more than one specific syndrome, and report fatigue, mood and sleep disturbances, and poor quality of life. The high degree of symptom comorbidity and a lack of definitive underlying etiology make these syndromes notoriously difficult to treat. The main purpose of this review article is to discuss potential mechanisms of centrally-driven pain amplification and how they may contribute to increased comorbidity, poorer pain outcomes, and decreased quality of life in patients diagnosed with centralized pain syndromes, as well as discuss emerging non-pharmacological therapies that improve symptomology associated with these syndromes. Abnormal regulation and output of the hypothalamic-pituitary-adrenal (HPA axis is commonly associated with centralized pain disorders. The HPA axis is the primary stress response system and its activation results in downstream production of cortisol and a dampening of the immune response. Patients with centralized pain syndromes often present with hyper- or hypocortisolism and evidence of altered downstream signaling from the HPA axis including increased Mast cell (MC infiltration and activation, which can lead to sensitization of nearby nociceptive afferents. Increased peripheral input via nociceptor activation can lead to “hyperalgesic priming” and/or “wind-up” and eventually to central sensitization through long term potentiation in the central nervous system. Other evidence of central modifications has been observed through brain imaging studies of functional

  14. Integrating Classical with Emerging Concepts for Better Understanding of Salinity Stress Tolerance Mechanisms in Rice

    Directory of Open Access Journals (Sweden)

    Navdeep Kaur

    2017-07-01

    Full Text Available Rice is an important cereal crop responsible for world's food security. The sensitivity of rice plants toward a range of abiotic stresses is a prime challenge for its overall growth and productivity. Among these, salinity is a major stress which results in a significant loss of global rice yield annually. For finding straightforward and strict future solutions in order to assure the food security to growing world population, understanding of the various mechanisms responsible for salt stress tolerance in rice is of paramount importance. In classical studies, identification of salt tolerant cultivars and the genetic markers linked to salt tolerance and breeding approaches have been given emphasis. It further affirmed on the identification of various pathways regulating the complex process of salt stress adaptation. However, only limited success has been achieved in these approaches as salt tolerance is a complex process and is governed by multiple factors. Hence, for better understanding of salt tolerance mechanisms, a comprehensive approach involving physiological, biochemical and molecular studies is much warranted. Modern experimental and genetic resources have provided a momentum in this direction and have provided molecular insights into different salt stress responsive pathways at the signaling and regulatory level. The integrative knowledge of classical and modern research of the understanding of salt stress adaptive pathways can help the researchers for designing effective strategies to fight against salt stress. Hence, the present review is focused on the understanding of the salt stress tolerance mechanisms in rice through the consolidative knowledge of classical and modern concepts. It further highlights the emerging new trends of salt stress adaptive pathways in rice.

  15. Final Report: Improving the understanding of the coupled thermal-mechanical-hydrologic behavior of consolidating granular salt

    Energy Technology Data Exchange (ETDEWEB)

    Stormont, John [Univ. of New Mexico, Albuquerque, NM (United States); Lampe, Brandon [Univ. of New Mexico, Albuquerque, NM (United States); Mills, Melissa [Univ. of New Mexico, Albuquerque, NM (United States); Paneru, Laxmi [Univ. of New Mexico, Albuquerque, NM (United States); Lynn, Timothy [Univ. of New Mexico, Albuquerque, NM (United States); Piya, Aayush [Univ. of New Mexico, Albuquerque, NM (United States)

    2017-09-09

    The goal of this project is to improve the understanding of key aspects of the coupled thermal-mechanical-hydrologic response of granular (or crushed) salt used as a seal material for shafts, drifts, and boreholes in mined repositories in salt. The project is organized into three tasks to accomplish this goal: laboratory measurements of granular salt consolidation (Task 1), microstructural observations on consolidated samples (Task 2), and constitutive model development and evaluation (Task 3). Task 1 involves laboratory measurements of salt consolidation along with thermal properties and permeability measurements conducted under a range of temperatures and stresses expected for potential mined repositories in salt. Testing focused on the role of moisture, temperature and stress state on the hydrologic (permeability) and thermal properties of consolidating granular salt at high fractional densities. Task 2 consists of microstructural observations made on samples after they have been consolidated to interpret deformation mechanisms and evaluate the ability of the constitutive model to predict operative mechanisms under different conditions. Task 3 concerns the development of the coupled thermal-mechanical-hydrologic constitutive model for granular salt consolidation. The measurements and observations in Tasks 1 and 2 were used to develop a thermal-mechanical constitutive model. Accomplishments and status from each of these efforts is reported in subsequent sections of this report

  16. Sex differences in ischaemic stroke: potential cellular mechanisms.

    Science.gov (United States)

    Chauhan, Anjali; Moser, Hope; McCullough, Louise D

    2017-04-01

    Stroke remains a leading cause of mortality and disability worldwide. More women than men have strokes each year, in part because women live longer. Women have poorer functional outcomes, are more likely to need nursing home care and have higher rates of recurrent stroke compared with men. Despite continued advancements in primary prevention, innovative acute therapies and ongoing developments in neurorehabilitation, stroke incidence and mortality continue to increase due to the aging of the U.S. Sex chromosomes (XX compared with XY), sex hormones (oestrogen and androgen), epigenetic regulation and environmental factors all contribute to sex differences. Ischaemic sensitivity varies over the lifespan, with females having an "ischaemia resistant" phenotype that wanes after menopause, which has recently been modelled in the laboratory. Pharmacological therapies for acute ischaemic stroke are limited. The only pharmacological treatment for stroke approved by the Food and Drug Administration (FDA) is tissue plasminogen activator (tPA), which must be used within hours of stroke onset and has a number of contraindications. Pre-clinical studies have identified a number of potentially efficacious neuroprotective agents; however, nothing has been effectively translated into therapy in clinical practice. This may be due, in part, to the overwhelming use of young male rodents in pre-clinical research, as well as lack of sex-specific design and analysis in clinical trials. The review will summarize the current clinical evidence for sex differences in ischaemic stroke, and will discuss sex differences in the cellular mechanisms of acute ischaemic injury, highlighting cell death and immune/inflammatory pathways that may contribute to these clinical differences. © 2017 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

  17. Understanding consumer motivations for interacting in online food communities – potential for innovation

    DEFF Research Database (Denmark)

    Jacobsen, Lina; Sørensen, Bjarne Taulo; Tudoran, Ana Alina

    This study contributes to the understanding of online user communities as a potential source of innovation. That would require an interest from users in interacting in such communities. In order to establish interaction, users must provide as well as consume information. However, depending...... on the innovation task, one may be more important than the other. It is therefore important to understand, how companies can increase user willingness to engage in these different interaction forms. This study investigates the influence of various motivation factors and user interests on intention to provide...... or consume information in online food communities. A survey was conducted among 1009 respondents followed by analysis based on Structural Equation Modelling. Results revealed the effect of motivation factors to be stronger than basic consumer interests indicating that companies can influence the intended...

  18. Review and assessment of mechanic village potentials for small ...

    African Journals Online (AJOL)

    This is suggested because developing countries are yet to enforce environmentally friendly automobile workshops and mechanic practice. If all automobile repair works in different cities are confined to mechanic villages, collection, preservation, recycling and reuse of spent oil will become effective. The goal is to stop the ...

  19. It's Rather like Learning a Language: Development of talk and conceptual understanding in mechanics lessons

    Science.gov (United States)

    Rincke, Karsten

    2011-01-01

    Although a broad literature exists concerning the development of conceptual understanding of force and other topics within mechanics, little is known about the role and development of students' talk about the subject. The paper presents an in-depth investigation of students' talk whilst being introduced to the concept of force. The main research goal was to investigate and understand how students develop an understanding of the concept of force and how they use and understand the term 'force'. Therefore, we make relation to the research field of students' preconceptions and the field of second language learning. Two classes of students (N = 47) were videotaped during a time period of nine lessons, each transcribed and analysed using a category system. Additional data were obtained via written tasks, logs kept by the students, and tests. The detailed analysis of the talk and the results of the tests indicate that students face difficulties in using the term 'force' scientifically similar to those in a foreign language instruction. Vygotsky already recognised a relationship between learning in science and learning a language. In this paper, important aspects of this relationship are discussed based upon empirical data. We conclude that in some respects it might be useful to make reference to the research related to language learning when thinking about improving science education. In particular, according to Selinker's concept of interlanguage describing language-learning processes within language instruction, the language used by the students during physics lessons can be viewed as a 'scientific interlanguage'.

  20. Understanding dental CAD/CAM for restorations--the digital workflow from a mechanical engineering viewpoint.

    Science.gov (United States)

    Tapie, L; Lebon, N; Mawussi, B; Fron Chabouis, H; Duret, F; Attal, J-P

    2015-01-01

    As digital technology infiltrates every area of daily life, including the field of medicine, so it is increasingly being introduced into dental practice. Apart from chairside practice, computer-aided design/computer-aided manufacturing (CAD/CAM) solutions are available for creating inlays, crowns, fixed partial dentures (FPDs), implant abutments, and other dental prostheses. CAD/CAM dental solutions can be considered a chain of digital devices and software for the almost automatic design and creation of dental restorations. However, dentists who want to use the technology often do not have the time or knowledge to understand it. A basic knowledge of the CAD/CAM digital workflow for dental restorations can help dentists to grasp the technology and purchase a CAM/CAM system that meets the needs of their office. This article provides a computer-science and mechanical-engineering approach to the CAD/CAM digital workflow to help dentists understand the technology.

  1. Toward Understanding Mechanisms Controlling Urea Delivery in a Coastal Plain Watershed

    Science.gov (United States)

    Tzilkowski, S. S.; Buda, A. R.; Boyer, E. W.; Bryant, R. B.; May, E. B.

    2012-12-01

    Improved understanding of nutrient mobilization and delivery to surface waters is critical to protecting water quality in agricultural watersheds. Urea, a form of organic nitrogen, is a common nutrient found in fertilizers, manures, and human waste, and is gaining recognition as an important driver of coastal eutrophication, particularly through the development of harmful algal blooms. While several studies have documented elevated urea concentrations in tributaries draining to the Chesapeake Bay, little is known about the potential sources and flow pathways responsible for urea delivery from the landscape to surface waters, as well as how these sources and pathways might vary with changing seasons, antecedent conditions, and storm types. In this study, we investigated hydrologic controls on urea delivery in the Manokin River watershed through the analysis of urea concentration dynamics and hysteresis patterns during seven storm events that occurred in 2010 and 2011. The Manokin River is a Coastal Plain watershed (11.1 km2) on the Delmarva Peninsula that drains directly to the Chesapeake Bay and is characterized by extensive rural development coupled with intensive agriculture, particularly poultry production. Sampling was conducted through monthly grab sampling at baseflow conditions and by time-weighted, automated (Sigma) samplers during stormflow events. Monitored storms were chosen to represent a spectrum of antecedent conditions based on precipitation and groundwater levels in the area. Flushing from the landscape during events was found to be the predominant urea delivery mechanism, as urea concentrations increased 3-9 times above baseflow concentrations during storms. The timing and number of flushes, as well as the degree of increased concentrations were dependent on antecedent conditions and the characteristics of the storm event. For instance, during an intense (13.7 mm hr-1), short-duration (4 hrs) storm in August of 2010 when antecedent conditions were

  2. Cognitive neuroepigenetics: the next evolution in our understanding of the molecular mechanisms underlying learning and memory?

    Science.gov (United States)

    Marshall, Paul; Bredy, Timothy W.

    2016-07-01

    A complete understanding of the fundamental mechanisms of learning and memory continues to elude neuroscientists. Although many important discoveries have been made, the question of how memories are encoded and maintained at the molecular level remains. So far, this issue has been framed within the context of one of the most dominant concepts in molecular biology, the central dogma, and the result has been a protein-centric view of memory. Here, we discuss the evidence supporting a role for neuroepigenetic mechanisms, which constitute dynamic and reversible, state-dependent modifications at all levels of control over cellular function, and their role in learning and memory. This neuroepigenetic view suggests that DNA, RNA and protein each influence one another to produce a holistic cellular state that contributes to the formation and maintenance of memory, and predicts a parallel and distributed system for the consolidation, storage and retrieval of the engram.

  3. Utilizing toxicogenomic data to understand chemical mechanism of action in risk assessment

    International Nuclear Information System (INIS)

    Wilson, Vickie S.; Keshava, Nagalakshmi; Hester, Susan; Segal, Deborah; Chiu, Weihsueh; Thompson, Chad M.; Euling, Susan Y.

    2013-01-01

    The predominant role of toxicogenomic data in risk assessment, thus far, has been one of augmentation of more traditional in vitro and in vivo toxicology data. This article focuses on the current available examples of instances where toxicogenomic data has been evaluated in human health risk assessment (e.g., acetochlor and arsenicals) which have been limited to the application of toxicogenomic data to inform mechanism of action. This article reviews the regulatory policy backdrop and highlights important efforts to ultimately achieve regulatory acceptance. A number of research efforts on specific chemicals that were designed for risk assessment purposes have employed mechanism or mode of action hypothesis testing and generating strategies. The strides made by large scale efforts to utilize toxicogenomic data in screening, testing, and risk assessment are also discussed. These efforts include both the refinement of methodologies for performing toxicogenomics studies and analysis of the resultant data sets. The current issues limiting the application of toxicogenomics to define mode or mechanism of action in risk assessment are discussed together with interrelated research needs. In summary, as chemical risk assessment moves away from a single mechanism of action approach toward a toxicity pathway-based paradigm, we envision that toxicogenomic data from multiple technologies (e.g., proteomics, metabolomics, transcriptomics, supportive RT-PCR studies) can be used in conjunction with one another to understand the complexities of multiple, and possibly interacting, pathways affected by chemicals which will impact human health risk assessment

  4. Reaction Mechanisms on Multiwell Potential Energy Surfaces in Combustion (and Atmospheric) Chemistry

    International Nuclear Information System (INIS)

    Osborn, David L.

    2017-01-01

    Chemical reactions occurring on a potential energy surface with multiple wells are ubiquitous in low temperature combustion and the oxidation of volatile organic compounds in earth’s atmosphere. The rich variety of structural isomerizations that compete with collisional stabilization make characterizing such complex-forming reactions challenging. This review describes recent experimental and theoretical advances that deliver increasingly complete views of their reaction mechanisms. New methods for creating reactive intermediates coupled with multiplexed measurements provide many experimental observables simultaneously. Automated methods to explore potential energy surfaces can uncover hidden reactive pathways, while master equation methods enable a holistic treatment of both sequential and well-skipping pathways. Our ability to probe and understand nonequilibrium effects and reaction sequences is increasing. These advances provide the fundamental science base for predictive models of combustion and the atmosphere that are crucial to address global challenges.

  5. Reaction Mechanisms on Multiwell Potential Energy Surfaces in Combustion (and Atmospheric) Chemistry

    Science.gov (United States)

    Osborn, David L.

    2017-05-01

    Chemical reactions occurring on a potential energy surface with multiple wells are ubiquitous in low-temperature combustion and in the oxidation of volatile organic compounds in Earth's atmosphere. The rich variety of structural isomerizations that compete with collisional stabilization makes characterizing such complex-forming reactions challenging. This review describes recent experimental and theoretical advances that deliver increasingly complete views of their reaction mechanisms. New methods for creating reactive intermediates coupled with multiplexed measurements provide many experimental observables simultaneously. Automated methods to explore potential energy surfaces can uncover hidden reactive pathways, and master equation methods enable a holistic treatment of both sequential and well-skipping pathways. Our ability to probe and understand nonequilibrium effects and reaction sequences is increasing. These advances provide the fundamental science base for predictive models of combustion and the atmosphere that are crucial to address global challenges.

  6. Role and potential mechanisms of anabolic resistance in sarcopenia

    Science.gov (United States)

    There is a pressing need to understand the aging process to better cope with its associated physical and societal costs. The age-related muscle wasting known as sarcopenia is a major contributor to the problems faced by the elderly. By hindering mobility and reducing strength, it greatly diminishes ...

  7. Potential Role of Probiotics in Mechanism of Intestinal Immunity

    Directory of Open Access Journals (Sweden)

    Imran Rashid Rajput and Wei Fen Li*

    2012-06-01

    Full Text Available Probiotics are nonpathogenic bacteria exert a constructive influence on health or physiology of the host. Effect of probiotics in the intestinal defense against variety of diseases is well known. The probiotics are involved in the mechanism of intestinal defense, support as antagonist against pathogens, improve intestinal epithelial layer and boost the innate as well as adaptive immunity. However these responses are also exerted by intestinal components. The intestinal components as well as probiotics play a reciprocal role to enhance the immune response of the individual. The possibilities of mechanism of action include the stimulation of epithelial cells, activation of dendritic cells via toll-like receptors (TLRs, conversely produce cytokines. These observations reviewed together advocate that specific immunomodulatory properties of probiotic bacteria should be focusing on mechanism of action via antigen presenting cells (APC.

  8. Performance potential of mechanical ventilation systems with minimized pressure loss

    DEFF Research Database (Denmark)

    Terkildsen, Søren; Svendsen, Svend

    2013-01-01

    In many locations mechanical ventilation has been the most widely used principle of ventilation over the last 50 years but the conventional system design must be revised to comply with future energy requirements. This paper examines the options and describes a concept for the design of mechanical....... This corresponds to 10-15% of the power consumption for conventional mechanical ventilation systems thus enabling the system to fulfil future energy requirements in buildings....... ventilation systems with minimal pressure loss and minimal energy use. This can provide comfort ventilation and avoid overheating through increased ventilation and night cooling. Based on this concept, a test system was designed for a fictive office building and its performance was documented using building...

  9. Investigating and improving student understanding of quantum mechanics in the context of single photon interference

    Science.gov (United States)

    Marshman, Emily; Singh, Chandralekha

    2017-06-01

    Single photon experiments involving a Mach-Zehnder interferometer can illustrate the fundamental principles of quantum mechanics, e.g., the wave-particle duality of a single photon, single photon interference, and the probabilistic nature of quantum measurement involving single photons. These experiments explicitly make the connection between the abstract quantum theory and concrete laboratory settings and have the potential to help students develop a solid grasp of the foundational issues in quantum mechanics. Here we describe students' conceptual difficulties with these topics in the context of Mach-Zehnder interferometer experiments with single photons and how the difficulties found in written surveys and individual interviews were used as a guide in the development of a Quantum Interactive Learning Tutorial (QuILT). The QuILT uses an inquiry-based approach to learning and takes into account the conceptual difficulties found via research to help upper-level undergraduate and graduate students learn about foundational quantum mechanics concepts using the concrete quantum optics context. It strives to help students learn the basics of quantum mechanics in the context of single photon experiment, develop the ability to apply fundamental quantum principles to experimental situations in quantum optics, and explore the differences between classical and quantum ideas in a concrete context. We discuss the findings from in-class evaluations suggesting that the QuILT was effective in helping students learn these abstract concepts.

  10. Progress in Understanding Degradation Mechanisms and Improving Stability in Organic Photovoltaics

    KAUST Repository

    Mateker, William R.

    2016-12-23

    Understanding the degradation mechanisms of organic photovoltaics is particularly important, as they tend to degrade faster than their inorganic counterparts, such as silicon and cadmium telluride. An overview is provided here of the main degradation mechanisms that researchers have identified so far that cause extrinsic degradation from oxygen and water, intrinsic degradation in the dark, and photo-induced burn-in. In addition, it provides methods for researchers to identify these mechanisms in new materials and device structures to screen them more quickly for promising long-term performance. These general strategies will likely be helpful in other photovoltaic technologies that suffer from insufficient stability, such as perovskite solar cells. Finally, the most promising lifetime results are highlighted and recommendations to improve long-term performance are made. To prevent degradation from oxygen and water for sufficiently long time periods, OPVs will likely need to be encapsulated by barrier materials with lower permeation rates of oxygen and water than typical flexible substrate materials. To improve stability at operating temperatures, materials will likely require glass transition temperatures above 100 °C. Methods to prevent photo-induced burn-in are least understood, but recent research indicates that using pure materials with dense and ordered film morphologies can reduce the burn-in effect.

  11. Progress in Understanding Degradation Mechanisms and Improving Stability in Organic Photovoltaics.

    Science.gov (United States)

    Mateker, William R; McGehee, Michael D

    2017-03-01

    Understanding the degradation mechanisms of organic photovoltaics is particularly important, as they tend to degrade faster than their inorganic counterparts, such as silicon and cadmium telluride. An overview is provided here of the main degradation mechanisms that researchers have identified so far that cause extrinsic degradation from oxygen and water, intrinsic degradation in the dark, and photo-induced burn-in. In addition, it provides methods for researchers to identify these mechanisms in new materials and device structures to screen them more quickly for promising long-term performance. These general strategies will likely be helpful in other photovoltaic technologies that suffer from insufficient stability, such as perovskite solar cells. Finally, the most promising lifetime results are highlighted and recommendations to improve long-term performance are made. To prevent degradation from oxygen and water for sufficiently long time periods, OPVs will likely need to be encapsulated by barrier materials with lower permeation rates of oxygen and water than typical flexible substrate materials. To improve stability at operating temperatures, materials will likely require glass transition temperatures above 100 °C. Methods to prevent photo-induced burn-in are least understood, but recent research indicates that using pure materials with dense and ordered film morphologies can reduce the burn-in effect. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Understanding comorbidity among internalizing problems: Integrating latent structural models of psychopathology and risk mechanisms

    Science.gov (United States)

    Hankin, Benjamin L.; Snyder, Hannah R.; Gulley, Lauren D.; Schweizer, Tina H.; Bijttebier, Patricia; Nelis, Sabine; Toh, Gim; Vasey, Michael W.

    2016-01-01

    It is well known that comorbidity is the rule, not the exception, for categorically defined psychiatric disorders, and this is also the case for internalizing disorders of depression and anxiety. This theoretical review paper addresses the ubiquity of comorbidity among internalizing disorders. Our central thesis is that progress in understanding this co-occurrence can be made by employing latent dimensional structural models that organize both psychopathology as well as vulnerabilities and risk mechanisms and by connecting the multiple levels of risk and psychopathology outcomes together. Different vulnerabilities and risk mechanisms are hypothesized to predict different levels of the structural model of psychopathology. We review the present state of knowledge based on concurrent and developmental sequential comorbidity patterns among common discrete psychiatric disorders in youth, and then we advocate for the use of more recent bifactor dimensional models of psychopathology (e.g., p factor, Caspi et al., 2014) that can help to explain the co-occurrence among internalizing symptoms. In support of this relatively novel conceptual perspective, we review six exemplar vulnerabilities and risk mechanisms, including executive function, information processing biases, cognitive vulnerabilities, positive and negative affectivity aspects of temperament, and autonomic dysregulation, along with the developmental occurrence of stressors in different domains, to show how these vulnerabilities can predict the general latent psychopathology factor, a unique latent internalizing dimension, as well as specific symptom syndrome manifestations. PMID:27739389

  13. Features of Knowledge Building in Biology: Understanding Undergraduate Students’ Ideas about Molecular Mechanisms

    Science.gov (United States)

    Southard, Katelyn; Wince, Tyler; Meddleton, Shanice; Bolger, Molly S.

    2016-01-01

    Research has suggested that teaching and learning in molecular and cellular biology (MCB) is difficult. We used a new lens to understand undergraduate reasoning about molecular mechanisms: the knowledge-integration approach to conceptual change. Knowledge integration is the dynamic process by which learners acquire new ideas, develop connections between ideas, and reorganize and restructure prior knowledge. Semistructured, clinical think-aloud interviews were conducted with introductory and upper-division MCB students. Interviews included a written conceptual assessment, a concept-mapping activity, and an opportunity to explain the biomechanisms of DNA replication, transcription, and translation. Student reasoning patterns were explored through mixed-method analyses. Results suggested that students must sort mechanistic entities into appropriate mental categories that reflect the nature of MCB mechanisms and that conflation between these categories is common. We also showed how connections between molecular mechanisms and their biological roles are part of building an integrated knowledge network as students develop expertise. We observed differences in the nature of connections between ideas related to different forms of reasoning. Finally, we provide a tentative model for MCB knowledge integration and suggest its implications for undergraduate learning. PMID:26931398

  14. Mechanisms of action of ligands of potential-dependent sodium channels.

    Science.gov (United States)

    Tikhonov, D B

    2008-06-01

    Potential-dependent sodium channels play a leading role in generating action potentials in excitable cells. Sodium channels are the site of action of a variety of modulator ligands. Despite numerous studies, the mechanisms of action of many modulators remain incompletely understood. The main reason that many important questions cannot be resolved is that there is a lack of precise data on the structures of the channels themselves. Structurally, potential-dependent sodium channels are members of the P-loop channel superfamily, which also include potassium and calcium channels and glutamate receptor channels. Crystallization of a series of potassium channels showed that it was possible to analyze the structures of different members of the superfamily using the "homologous modeling" method. The present study addresses model investigations of the actions of ligands of sodium channels, including tetrodotoxin and batrachotoxin, as well as local anesthetics. Comparison of experimental data on sodium channel ligands with x-ray analysis data allowed us to reach a new level of understanding of the mechanisms of channel modulation and to propose a series of experimentally verifiable hypotheses.

  15. The use of gamma-survey measurements to better understand radon potential in urban areas.

    Science.gov (United States)

    Berens, Andrew S; Diem, Jeremy; Stauber, Christine; Dai, Dajun; Foster, Stephanie; Rothenberg, Richard

    2017-12-31

    Accounting for as much as 14% of all lung cancers worldwide, cumulative radon progeny exposure is the leading cause of lung cancer among never-smokers both internationally and in the United States. To understand the risk of radon progeny exposure, studies have mapped radon potential using aircraft-based measurements of gamma emissions. However, these efforts are hampered in urban areas where the built environment obstructs aerial data collection. To address part of this limitation, this study aimed to evaluate the effectiveness of using in situ gamma readings (taken with a scintillation probe attached to a ratemeter) to assess radon potential in an urban environment: DeKalb County, part of the Atlanta metropolitan area, Georgia, USA. After taking gamma measurements at 402 survey sites, empirical Bayesian kriging was used to create a continuous surface of predicted gamma readings for the county. We paired these predicted gamma readings with indoor radon concentration data from 1351 residential locations. Statistical tests showed the interpolated gamma values were significantly but weakly positively related with indoor radon concentrations, though this relationship is decreasingly informative at finer geographic scales. Geology, gamma readings, and indoor radon were interrelated, with granitic gneiss generally having the highest gamma readings and highest radon concentrations and ultramafic rock having the lowest of each. Our findings indicate the highest geogenic radon potential may exists in the relatively undeveloped southeastern part of the county. It is possible that in situ gamma, in concert with other variables, could offer an alternative to aerial radioactivity measurements when determining radon potential, though future work will be needed to address this project's limitations. Published by Elsevier B.V.

  16. Understanding reaction mechanisms in organic chemistry from catastrophe theory applied to the electron localization function topology.

    Science.gov (United States)

    Polo, Victor; Andres, Juan; Berski, Slawomir; Domingo, Luis R; Silvi, Bernard

    2008-08-07

    Thom's catastrophe theory applied to the evolution of the topology of the electron localization function (ELF) gradient field constitutes a way to rationalize the reorganization of electron pairing and a powerful tool for the unambiguous determination of the molecular mechanisms of a given chemical reaction. The identification of the turning points connecting the ELF structural stability domains along the reaction pathway allows a rigorous characterization of the sequence of electron pair rearrangements taking place during a chemical transformation, such as multiple bond forming/breaking processes, ring closure processes, creation/annihilation of lone pairs, transformations of C-C multiple bonds into single ones. The reaction mechanism of some relevant organic reactions: Diels-Alder, 1,3-dipolar cycloaddition and Cope rearrangement are reviewed to illustrate the potential of the present approach.

  17. On Mechanical Mixed Potential, Content and Co-Content

    NARCIS (Netherlands)

    Jeltsema, Dimitri; Scherpen, Jacquelien M.A.

    2003-01-01

    In this paper a novel co-energy modelling framework is presented for a relevant class of linear and nonlinear mechanical systems. The approach uses the classical Brayton-Moser equations which are deduced from a (port-)Hamiltonian description. The approach allows classical results from electrical

  18. Potential mechanisms behind contrast medium-induced nephropathy

    African Journals Online (AJOL)

    How contrast medium-induced nephropathy (CIN) comes about is poorly understood, although CIN is a common cause of acute renal failure. Hitherto, the various studies performed have led to different interpretations and partially contradictory conclusions. This article aimed to review the mechanisms underlying CIN and to ...

  19. Child Care Subsidy Use and Child Development: Potential Causal Mechanisms

    Science.gov (United States)

    Hawkinson, Laura E.

    2011-01-01

    Research using an experimental design is needed to provide firm causal evidence on the impacts of child care subsidy use on child development, and on underlying causal mechanisms since subsidies can affect child development only indirectly via changes they cause in children's early experiences. However, before costly experimental research is…

  20. Antioxidative and proline potentials as a protective mechanism in ...

    African Journals Online (AJOL)

    Stress can define as all negative factors affecting plant growth. One of the most important problems among stress factors is salt stress. Antioxidant responses are tested in Soybean (Glycine max. L.) cv., “A3935” grown under 0, 50, 100 and 150 mM NaCl in order to investigate the plants protective mechanisms against salt ...

  1. Potential mechanisms behind the antioxidant actions of prolactin in the retina.

    Science.gov (United States)

    Thébault, Stéphanie

    2017-07-01

    Causes for age-related retinal diseases are numerous and complex, and they are intertwined with the natural vision decline that accompanies aging. The elucidation of endogenous mechanisms that help maintain retinal function under conditions that are threatening for the eye and happen during natural aging is therefore critical in developing new prevention and therapeutic strategies against age-related retinal degeneration. Our lab recently reported that the hormone of lactation, prolactin, helps the retinal pigment epithelium to survive via antioxidant actions that result in the inhibition of sirtuin2-dependent cell death (EbioMedicine issue of May). The mechanism behind the antioxidant activity of prolactin remains elusive. The main purposes of my commentary are to discuss mechanisms that could explain this effect in the context of previously identified defense mechanisms against oxidative stress and focus particularly on the potential regulation of reduced glutathione levels by prolactin. I also briefly comment on how our study contributes to cell biology, which as the foundational science for understanding neurodegeneration, may accelerate progress in disease prevention and cures. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. The Cardioprotective Effects of Hydrogen Sulfide in Heart Diseases: From Molecular Mechanisms to Therapeutic Potential.

    Science.gov (United States)

    Shen, Yaqi; Shen, Zhuqing; Luo, Shanshan; Guo, Wei; Zhu, Yi Zhun

    2015-01-01

    Hydrogen sulfide (H2S) is now recognized as a third gaseous mediator along with nitric oxide (NO) and carbon monoxide (CO), though it was originally considered as a malodorous and toxic gas. H2S is produced endogenously from cysteine by three enzymes in mammalian tissues. An increasing body of evidence suggests the involvement of H2S in different physiological and pathological processes. Recent studies have shown that H2S has the potential to protect the heart against myocardial infarction, arrhythmia, hypertrophy, fibrosis, ischemia-reperfusion injury, and heart failure. Some mechanisms, such as antioxidative action, preservation of mitochondrial function, reduction of apoptosis, anti-inflammatory responses, angiogenic actions, regulation of ion channel, and interaction with NO, could be responsible for the cardioprotective effect of H2S. Although several mechanisms have been identified, there is a need for further research to identify the specific molecular mechanism of cardioprotection in different cardiac diseases. Therefore, insight into the molecular mechanisms underlying H2S action in the heart may promote the understanding of pathophysiology of cardiac diseases and lead to new therapeutic targets based on modulation of H2S production.

  3. The Cardioprotective Effects of Hydrogen Sulfide in Heart Diseases: From Molecular Mechanisms to Therapeutic Potential

    Directory of Open Access Journals (Sweden)

    Yaqi Shen

    2015-01-01

    Full Text Available Hydrogen sulfide (H2S is now recognized as a third gaseous mediator along with nitric oxide (NO and carbon monoxide (CO, though it was originally considered as a malodorous and toxic gas. H2S is produced endogenously from cysteine by three enzymes in mammalian tissues. An increasing body of evidence suggests the involvement of H2S in different physiological and pathological processes. Recent studies have shown that H2S has the potential to protect the heart against myocardial infarction, arrhythmia, hypertrophy, fibrosis, ischemia-reperfusion injury, and heart failure. Some mechanisms, such as antioxidative action, preservation of mitochondrial function, reduction of apoptosis, anti-inflammatory responses, angiogenic actions, regulation of ion channel, and interaction with NO, could be responsible for the cardioprotective effect of H2S. Although several mechanisms have been identified, there is a need for further research to identify the specific molecular mechanism of cardioprotection in different cardiac diseases. Therefore, insight into the molecular mechanisms underlying H2S action in the heart may promote the understanding of pathophysiology of cardiac diseases and lead to new therapeutic targets based on modulation of H2S production.

  4. Icepod Plus Potential Field: An Integrated Approach For Understanding Ice Shelf Processes

    Science.gov (United States)

    Frearson, N.

    2015-12-01

    Warm water flowing beneath the large floating ice shelves in Antarctica will play an important role in how fast sea level rises. The lack of detailed bathymetry beneath the large ice shelves and lack of understanding of their internal structure inherently limits our knowledge of how ice shelves will thin and collapse. Understanding the bathymetry beneath the remaining ice shelves is critical to understanding how ice shelves will thin in the future and how that will impact the flux of ice into the global ocean. The Ross Ice Shelf, the largest ice shelf remaining on our planet, buttresses the West Antarctic Ice Sheet. The bathymetry beneath the Ross Ice Shelf is the least explored piece of ocean floor on our planet. The IcePod is a compact integrated ice imaging system developed for use on any C-130 aircraft developed with NSF support. The initial development program was targeted towards investigating glacial and ice-sheet processes. In this program, deep and shallow ice radars were developed. Optical instruments, including a scanning laser, Infra-red camera and visible wave camera were integrated into the pod. We have expanded the IcePod instrument suite to include the potential field measurements of magnetic and gravity anomalies with support from the Moore Foundation. During the development, a total field cesium sensor magnetometer and 3-axis fluxgate from previously funded work were also incorporated into the pod. Their behavioral response to being located close to high-frequency electronics, power supplies and metallic objects were studied. We describe in part some of that development process and the positive findings that resulted. The Icepod group is also actively pursuing the development, modification and incorporation of a new gravimeter into the suite of instruments available to the program and is investigating reduction in size of this that may eventually lead to incorporating the gravimeter into the pod itself. As part of this program we are also

  5. Understanding the Impact of Root Morphology on Overturning Mechanisms: A Modelling Approach

    Science.gov (United States)

    Fourcaud, Thierry; Ji, Jin-Nan; Zhang, Zhi-Qiang; Stokes, Alexia

    2008-01-01

    Background and Aims The Finite Element Method (FEM) has been used in recent years to simulate overturning processes in trees. This study aimed at using FEM to determine the role of individual roots in tree anchorage with regard to different rooting patterns, and to estimate stress distribution in the soil and roots during overturning. Methods The FEM was used to carry out 2-D simulations of tree uprooting in saturated soft clay and loamy sand-like soil. The anchorage model consisted of a root system embedded in a soil block. Two root patterns were used and individual roots removed to determine their contribution to anchorage. Key Results In clay-like soil the size of the root–soil plate formed during overturning was defined by the longest roots. Consequently, all other roots localized within this plate had no influence on anchorage strength. In sand-like soil, removing individual root elements altered anchorage resistance. This result was due to a modification of the shape and size of the root–soil plate, as well as the location of the rotation axis. The tap root and deeper roots had more influence on overturning resistance in sand-like soil compared with clay-like soil. Mechanical stresses were higher in the most superficial roots and also in leeward roots in sand-like soil. The relative difference in stresses between the upper and lower sides of lateral roots was sensitive to root insertion angle. Assuming that root eccentricity is a response to mechanical stresses, these results explain why eccentricity differs depending on root architecture. Conclusions A simple 2-D Finite Element model was developed to better understand the mechanisms involved during tree overturning. It has been shown how root system morphology and soil mechanical properties can modify the shape of the root plate slip surface as well as the position of the rotation axis, which are major components of tree anchorage. PMID:17942593

  6. Using the glacial geomorphology of palaeo-ice streams to understand mechanisms of ice sheet collapse

    Science.gov (United States)

    Stokes, Chris R.; Margold, Martin; Clark, Chris; Tarasov, Lev

    2017-04-01

    Processes which bring about ice sheet deglaciation are critical to our understanding of glacial-interglacial cycles and ice sheet sensitivity to climate change. The precise mechanisms of deglaciation are also relevant to our understanding of modern-day ice sheet stability and concerns over global sea level rise. Mass loss from ice sheets can be broadly partitioned between melting and a 'dynamic' component whereby rapidly-flowing ice streams/outlet glaciers transfer ice from the interior to the oceans. Surface and basal melting (e.g. of ice shelves) are closely linked to atmospheric and oceanic conditions, but the mechanisms that drive dynamic changes in ice stream discharge are more complex, which generates much larger uncertainties about their future contribution to ice sheet mass loss and sea level rise. A major problem is that observations of modern-day ice streams typically span just a few decades and, at the ice-sheet scale, it is unclear how the entire drainage network of ice streams evolves during deglaciation. A key question is whether ice streams might increase and sustain rates of mass loss over centuries or millennia, beyond those expected for a given ocean-climate forcing. To address this issue, numerous workers have sought to understand ice stream dynamics over longer time-scales using their glacial geomorphology in the palaeo-record. Indeed, our understanding of their geomorphology has grown rapidly in the last three decades, from almost complete ignorance to a detailed knowledge of their geomorphological products. Building on this body of work, this paper uses the glacial geomorphology of 117 ice streams in the North American Laurentide Ice Sheet to reconstruct their activity during its deglaciation ( 22,000 to 7,000 years ago). Ice stream activity was characterised by high variability in both time and space, with ice streams switching on and off in different locations. During deglaciation, we find that their overall number decreased, they occupied a

  7. Performance potential of mechanical ventilation systems with minimized pressure loss

    DEFF Research Database (Denmark)

    Terkildsen, Søren; Svendsen, Svend

    2013-01-01

    simulations that quantify fan power consumption, heating demand and indoor environmental conditions. The system was designed with minimal pressure loss in the duct system and heat exchanger. Also, it uses state-of-the-art components such as electrostatic precipitators, diffuse ceiling inlets and demand......In many locations mechanical ventilation has been the most widely used principle of ventilation over the last 50 years but the conventional system design must be revised to comply with future energy requirements. This paper examines the options and describes a concept for the design of mechanical...... ventilation systems with minimal pressure loss and minimal energy use. This can provide comfort ventilation and avoid overheating through increased ventilation and night cooling. Based on this concept, a test system was designed for a fictive office building and its performance was documented using building...

  8. Mental imagery in music performance: underlying mechanisms and potential benefits.

    Science.gov (United States)

    Keller, Peter E

    2012-04-01

    This paper examines the role of mental imagery in music performance. Self-reports by musicians, and various other sources of anecdotal evidence, suggest that covert auditory, motor, and/or visual imagery facilitate multiple aspects of music performance. The cognitive and motor mechanisms that underlie such imagery include working memory, action simulation, and internal models. Together these mechanisms support the generation of anticipatory images that enable thorough action planning and movement execution that is characterized by efficiency, temporal precision, and biomechanical economy. In ensemble performance, anticipatory imagery may facilitate interpersonal coordination by enhancing online predictions about others' action timing. Overlap in brain regions subserving auditory imagery and temporal prediction is consistent with this view. It is concluded that individual differences in anticipatory imagery may be a source of variation in expressive performance excellence and the quality of ensemble cohesion. Engaging in effortful musical imagery is therefore justified when artistic perfection is the goal. © 2012 New York Academy of Sciences.

  9. Sleep Duration and Diabetes Risk: Population Trends and Potential Mechanisms

    Science.gov (United States)

    Grandner, Michael A.; Seixas, Azizi; Shetty, Safal; Shenoy, Sundeep

    2016-01-01

    Sleep is important for regulating many physiologic functions that relate to metabolism. Because of this, there is substantial evidence to suggest that sleep habits and sleep disorders are related to diabetes risk. In specific, insufficient sleep duration and/or sleep restriction in the laboratory, poor sleep quality, and sleep disorders such as insomnia and sleep apnea have all been associated with diabetes risk. This research spans epidemiologic and laboratory studies. Both physiologic mechanisms such as insulin resistance, decreased leptin, and increased ghrelin and inflammation and behavioral mechanisms such as increased food intake, impaired decision-making, and increased likelihood of other behavioral risk factors such as smoking, sedentary behavior, and alcohol use predispose to both diabetes and obesity, which itself is an important diabetes risk factor. This review describes the evidence linking sleep and diabetes risk at the population and laboratory levels. PMID:27664039

  10. Molecular understanding of a potential functional link between antimicrobial and amyloid peptides.

    Science.gov (United States)

    Zhang, Mingzhen; Zhao, Jun; Zheng, Jie

    2014-10-14

    Antimicrobial and amyloid peptides do not share common sequences, typical secondary structures, or normal biological activity but both the classes of peptides exhibit membrane-disruption ability to induce cell toxicity. Different membrane-disruption mechanisms have been proposed for antimicrobial and amyloid peptides, individually, some of which are not exclusive to either peptide type, implying that certain common principles may govern the folding and functions of different cytolytic peptides and associated membrane disruption mechanisms. Particularly, some antimicrobial and amyloid peptides have been identified to have dual complementary amyloid and antimicrobial properties, suggesting a potential functional link between amyloid and antimicrobial peptides. Given that some similar structural and membrane-disruption characteristics exist between the two classes of peptides, this review summarizes major findings, recent advances, and future challenges related to antimicrobial and amyloid peptides and strives to illustrate the similarities, differences, and relationships in the sequences, structures, and membrane interaction modes between amyloid and antimicrobial peptides, with a special focus on direct interactions of the peptides with the membranes. We hope that this review will stimulate further research at the interface of antimicrobial and amyloid peptides - which has been studied less intensively than either type of peptides - to decipher a possible link between both amyloid pathology and antimicrobial activity, which can guide drug design and peptide engineering to influence peptide-membrane interactions important in human health and diseases.

  11. Antioxidative and proline potentials as a protective mechanism in ...

    African Journals Online (AJOL)

    Jane

    2011-07-04

    Jul 4, 2011 ... The plants were uprooted randomly on 30 DAS and the enzymatic antioxidant potentials were analyzed. The fresh and dry weights and the chlorophyll content are reduced with increasing NaCl concentration. Proline concentration increased at high salinity compared to untreated plants. Moreover, salinity ...

  12. Antioxidative and proline potentials as a protective mechanism in ...

    African Journals Online (AJOL)

    Jane

    2011-07-04

    Jul 4, 2011 ... Stress can define as all negative factors affecting plant growth. One of the most important problems among stress factors is salt stress. Antioxidant responses ... High-salt stress disrupts the homeostasis in water potential and ion distribution at both the cellular and the whole plant levels (Errabii et al., 2007).

  13. Mechanism of the potentiation of thrombolysis by pentoxifylline (Trental)

    Energy Technology Data Exchange (ETDEWEB)

    Ambrus, J.L.; Ambrus, C.M.; Mahfzah, M.; Markus, J.A.; Klein, E.; Gastpar, H.

    1987-01-01

    Streptokinase induced thrombolysis of radioactive labeled human fibrin clots was potentiated by simultaneous treatment with pentoxifylline (Trental). This appears to be due in part to the prevention of platelet aggregation on the clot. In addition, release of t-PA and PgI2 from the endothelium and increases in red cell deformability may also play a role.

  14. Gender differences in conceptual understanding of Newtonian mechanics: a UK cross-institution comparison

    International Nuclear Information System (INIS)

    Bates, Simon; Donnelly, Robyn; MacPhee, Cait; Sands, David; Birch, Marion; Walet, Niels R

    2013-01-01

    We present the results of a combined study from three UK universities where we investigate the existence and persistence of a performance gender gap in conceptual understanding of Newtonian mechanics. Using the Force Concept Inventory, we find that students at all three universities exhibit a statistically significant gender gap, with males outperforming females. This gap is narrowed but not eliminated after instruction, using a variety of instructional approaches. Furthermore, we find that before instruction the quartile with the lowest performance on the diagnostic instrument comprises a disproportionately high fraction (∼50%) of the total female cohort. The majority of these students remain in the lowest-performing quartile post-instruction. Analysis of responses to individual items shows that male students outperform female students on practically all items on the instrument. Comparing the performance of the same group of students on end-of-course examinations, we find no statistically significant gender gaps. (paper)

  15. Emerging understanding of the mechanism of action of Bronchial Thermoplasty in asthma.

    Science.gov (United States)

    d'Hooghe, J N S; Ten Hacken, N H T; Weersink, E J M; Sterk, P J; Annema, J T; Bonta, P I

    2018-01-01

    Bronchial Thermoplasty (BT) is an endoscopic treatment for moderate-to-severe asthma patients who are uncontrolled despite optimal medical therapy. Effectiveness of BT has been demonstrated in several randomized clinical trials. However, the asthma phenotype that benefits most of this treatment is unclear, partly because the mechanism of action is incompletely understood. BT was designed to reduce the amount of airway smooth muscle (ASM), but additional direct and indirect effects on airway pathophysiology are expected. This review will provide an overview of the different components of airway pathophysiology including remodeling, with the ASM as the key player. Current concepts in the understanding of BT clinical effectiveness with a focus on its impact on airway remodeling will be reviewed. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  16. The contributions of cognitive neuroscience and neuroimaging to understanding mechanisms of behavior change in addiction.

    Science.gov (United States)

    Morgenstern, Jon; Naqvi, Nasir H; Debellis, Robert; Breiter, Hans C

    2013-06-01

    In the last decade, there has been an upsurge of interest in understanding the mechanisms of behavior change (MOBC) and effective behavioral interventions as a strategy to improve addiction-treatment efficacy. However, there remains considerable uncertainty about how treatment research should proceed to address the MOBC issue. In this article, we argue that limitations in the underlying models of addiction that inform behavioral treatment pose an obstacle to elucidating MOBC. We consider how advances in the cognitive neuroscience of addiction offer an alternative conceptual and methodological approach to studying the psychological processes that characterize addiction, and how such advances could inform treatment process research. In addition, we review neuroimaging studies that have tested aspects of neurocognitive theories as a strategy to inform addiction therapies and discuss future directions for transdisciplinary collaborations across cognitive neuroscience and MOBC research. 2013 APA, all rights reserved

  17. Limb Remote Ischemic Conditioning: Mechanisms, Anesthetics, and the Potential for Expanding Therapeutic Options

    Directory of Open Access Journals (Sweden)

    Gangling Chen

    2018-02-01

    Full Text Available Novel and innovative approaches are essential in developing new treatments and improving clinical outcomes in patients with ischemic stroke. Remote ischemic conditioning (RIC is a series of mechanical interruptions in blood flow of a distal organ, following end organ reperfusion, shown to significantly reduce infarct size through inhibition of oxidation and inflammation. Ischemia/reperfusion (I/R is what ultimately leads to the irreversible brain damage and clinical picture seen in stroke patients. There have been several reports and reviews about the potential of RIC in acute ischemic stroke; however, the focus here is a comprehensive look at the differences in the three types of RIC (remote pre-, per-, and postconditioning. There are some limited uses of preconditioning in acute ischemic stroke due to the unpredictability of the ischemic event; however, it does provide the identification of biomarkers for clinical studies. Remote limb per- and postconditioning offer a more promising treatment during patient care as they can be harnessed during or after the initial ischemic insult. Though further research is needed, it is imperative to discuss the importance of preclinical data in understanding the methods and mechanisms involved in RIC. This understanding will facilitate translation to a clinically feasible paradigm for use in the hospital setting.

  18. Limb Remote Ischemic Conditioning: Mechanisms, Anesthetics, and the Potential for Expanding Therapeutic Options

    Science.gov (United States)

    Chen, Gangling; Thakkar, Mrugesh; Robinson, Christopher; Doré, Sylvain

    2018-01-01

    Novel and innovative approaches are essential in developing new treatments and improving clinical outcomes in patients with ischemic stroke. Remote ischemic conditioning (RIC) is a series of mechanical interruptions in blood flow of a distal organ, following end organ reperfusion, shown to significantly reduce infarct size through inhibition of oxidation and inflammation. Ischemia/reperfusion (I/R) is what ultimately leads to the irreversible brain damage and clinical picture seen in stroke patients. There have been several reports and reviews about the potential of RIC in acute ischemic stroke; however, the focus here is a comprehensive look at the differences in the three types of RIC (remote pre-, per-, and postconditioning). There are some limited uses of preconditioning in acute ischemic stroke due to the unpredictability of the ischemic event; however, it does provide the identification of biomarkers for clinical studies. Remote limb per- and postconditioning offer a more promising treatment during patient care as they can be harnessed during or after the initial ischemic insult. Though further research is needed, it is imperative to discuss the importance of preclinical data in understanding the methods and mechanisms involved in RIC. This understanding will facilitate translation to a clinically feasible paradigm for use in the hospital setting. PMID:29467715

  19. Smartphone users: Understanding how security mechanisms are perceived and new persuasive methods

    Science.gov (United States)

    Alsaleh, Mansour; Alomar, Noura; Alarifi, Abdulrahman

    2017-01-01

    Protecting smartphones against security threats is a multidimensional problem involving human and technological factors. This study investigates how smartphone users’ security- and privacy-related decisions are influenced by their attitudes, perceptions, and understanding of various security threats. In this work, we seek to provide quantified insights into smartphone users’ behavior toward multiple key security features including locking mechanisms, application repositories, mobile instant messaging, and smartphone location services. To the best of our knowledge, this is the first study that reveals often unforeseen correlations and dependencies between various privacy- and security-related behaviors. Our work also provides evidence that making correct security decisions might not necessarily correlate with individuals’ awareness of the consequences of security threats. By comparing participants’ behavior and their motives for adopting or ignoring certain security practices, we suggest implementing additional persuasive approaches that focus on addressing social and technological aspects of the problem. On the basis of our findings and the results presented in the literature, we identify the factors that might influence smartphone users’ security behaviors. We then use our understanding of what might drive and influence significant behavioral changes to propose several platform design modifications that we believe could improve the security levels of smartphones. PMID:28297719

  20. Smartphone users: Understanding how security mechanisms are perceived and new persuasive methods.

    Science.gov (United States)

    Alsaleh, Mansour; Alomar, Noura; Alarifi, Abdulrahman

    2017-01-01

    Protecting smartphones against security threats is a multidimensional problem involving human and technological factors. This study investigates how smartphone users' security- and privacy-related decisions are influenced by their attitudes, perceptions, and understanding of various security threats. In this work, we seek to provide quantified insights into smartphone users' behavior toward multiple key security features including locking mechanisms, application repositories, mobile instant messaging, and smartphone location services. To the best of our knowledge, this is the first study that reveals often unforeseen correlations and dependencies between various privacy- and security-related behaviors. Our work also provides evidence that making correct security decisions might not necessarily correlate with individuals' awareness of the consequences of security threats. By comparing participants' behavior and their motives for adopting or ignoring certain security practices, we suggest implementing additional persuasive approaches that focus on addressing social and technological aspects of the problem. On the basis of our findings and the results presented in the literature, we identify the factors that might influence smartphone users' security behaviors. We then use our understanding of what might drive and influence significant behavioral changes to propose several platform design modifications that we believe could improve the security levels of smartphones.

  1. Understanding dental CAD/CAM for restorations--accuracy from a mechanical engineering viewpoint.

    Science.gov (United States)

    Tapie, Laurent; Lebon, Nicolas; Mawussi, Bernardin; Fron-Chabouis, Hélène; Duret, Francois; Attal, Jean-Pierre

    2015-01-01

    As is the case in the field of medicine, as well as in most areas of daily life, digital technology is increasingly being introduced into dental practice. Computer-aided design/ computer-aided manufacturing (CAD/CAM) solutions are available not only for chairside practice but also for creating inlays, crowns, fixed partial dentures (FPDs), implant abutments, and other dental prostheses. CAD/CAM dental practice can be considered as the handling of devices and software processing for the almost automatic design and creation of dental restorations. However, dentists who want to use dental CAD/CAM systems often do not have enough information to understand the variations offered by such technology practice. Knowledge of the random and systematic errors in accuracy with CAD/CAM systems can help to achieve successful restorations with this technology, and help with the purchasing of a CAD/CAM system that meets the clinical needs of restoration. This article provides a mechanical engineering viewpoint of the accuracy of CAD/ CAM systems, to help dentists understand the impact of this technology on restoration accuracy.

  2. Investigating and improving student understanding of the expectation values of observables in quantum mechanics

    Science.gov (United States)

    Marshman, Emily; Singh, Chandralekha

    2017-07-01

    The expectation value of an observable is an important concept in quantum mechanics since measurement outcomes are, in general, probabilistic and we only have information about the probability distribution of measurement outcomes in a given quantum state of a system. However, we find that upper-level undergraduate and PhD students in physics have both conceptual and procedural difficulties when determining the expectation value of a physical observable in a given quantum state in terms of the eigenstates and eigenvalues of the corresponding operator, especially when using Dirac notation. Here we first describe the difficulties that these students have with determining the expectation value of an observable in Dirac notation. We then discuss how the difficulties found via student responses to written surveys and individual interviews were used as a guide in the development of a quantum interactive learning tutorial (QuILT) to help students develop a good grasp of the expectation value. The QuILT strives to help students integrate conceptual understanding and procedural skills to develop a coherent understanding of the expectation value. We discuss the effectiveness of the QuILT in helping students learn this concept from in-class evaluations.

  3. Smartphone users: Understanding how security mechanisms are perceived and new persuasive methods.

    Directory of Open Access Journals (Sweden)

    Mansour Alsaleh

    Full Text Available Protecting smartphones against security threats is a multidimensional problem involving human and technological factors. This study investigates how smartphone users' security- and privacy-related decisions are influenced by their attitudes, perceptions, and understanding of various security threats. In this work, we seek to provide quantified insights into smartphone users' behavior toward multiple key security features including locking mechanisms, application repositories, mobile instant messaging, and smartphone location services. To the best of our knowledge, this is the first study that reveals often unforeseen correlations and dependencies between various privacy- and security-related behaviors. Our work also provides evidence that making correct security decisions might not necessarily correlate with individuals' awareness of the consequences of security threats. By comparing participants' behavior and their motives for adopting or ignoring certain security practices, we suggest implementing additional persuasive approaches that focus on addressing social and technological aspects of the problem. On the basis of our findings and the results presented in the literature, we identify the factors that might influence smartphone users' security behaviors. We then use our understanding of what might drive and influence significant behavioral changes to propose several platform design modifications that we believe could improve the security levels of smartphones.

  4. EGFR transactivation: mechanisms, pathophysiology and potential therapies in cardiovascular system

    Science.gov (United States)

    Forrester, Steven J.; Kawai, Tatsuo; Elliott, Katherine J.; O’Brien, Shannon; Thomas, Walter; Harris, Raymond C.; Eguchi, Satoru

    2017-01-01

    Accumulating studies suggest that the epidermal growth factor receptor (EGFR) activation is associated with the physiology and pathophysiology of the cardiovascular system, and inhibition of EGFR activity is emerging as a potential therapeutic strategy to treat diseases, including hypertension, cardiac hypertrophy, renal fibrosis and abdominal aortic aneurysm. The capacity of G protein-coupled receptor (GPCR) agonists, such as angiotensin II (AngII), to promote EGFR signaling is well described – a process termed EGFR “transactivation” – yet delineating the molecular processes and functional relevance of this crosstalk has been challenging. Moreover, these critical findings are dispersed among many different fields. The aim of our review is to highlight the recent advancement of the signaling cascades and downstream consequences of EGFR transactivation within the cardiovascular renal system in vitro and in vivo. We will also focus on linking EGFR transactivation to animal models of the disease as well as the potential therapeutic applications. PMID:26566153

  5. Towards understanding the mechanisms and the kinetics of nanoparticle penetration through protective gloves

    International Nuclear Information System (INIS)

    Vinches, L; Boutrigue, N; Zemzem, M; Hallé, S; Peyrot, C; Lemarchand, L; Wilkinson, K J; Tufenkji, N

    2015-01-01

    Parallel to the increased use of engineered nanoparticles (ENP) in the formulation of commercial products or in medicine, numerous health and safety agencies have recommended the application of the precautionary principle to handle ENP; namely, the recommendation to use protective gloves against chemicals. However, recent studies reveal the penetration of titanium dioxide nanoparticles through nitrile rubber protective gloves in conditions simulating occupational use. This project is designed to understand the links between the penetration of gold nanoparticles (nAu) through nitrile rubber protective gloves and the mechanical and physical behaviour of the elastomer material subjected to conditions simulating occupational use (i.e., mechanical deformations (MD) and sweat). Preliminary analyses show that nAu suspensions penetrate selected glove materials after exposure to prolonged (3 hours) dynamic deformations. Significant morphological changes are observed on the outer surface of the glove sample; namely, the number and the surface of the micropores on the surface increase. Moreover, nitrile rubber protective gloves are also shown to be sensitive to the action of nAu suspension and to the action of the saline solution used to simulate sweat (swelling). (paper)

  6. The use of micro-/milli-fluidics to better understand the mechanisms behind deep venous thrombosis

    Science.gov (United States)

    Schofield, Zoe; Alexiadis, Alessio; Brill, Alexander; Nash, Gerard; Vigolo, Daniele

    2016-11-01

    Deep venous thrombosis (DVT) is a dangerous and painful condition in which blood clots form in deep veins (e.g., femoral vein). If these clots become unstable and detach from the thrombus they can be delivered to the lungs resulting in a life threatening complication called pulmonary embolism (PE). Mechanisms of clot development in veins remain unclear but researchers suspect that the specific flow patterns in veins, especially around the valve flaps, play a fundamental role. Here we show how it is now possible to mimic the current murine model by developing micro-/milli-fluidic experiments. We exploited a novel detection technique, ghost particle velocimetry (GPV), to analyse the velocity profiles for various geometries. These vary from regular microfluidics with a rectangular cross section with a range of geometries (mimicking the presence of side and back branches in veins, closed side branch and flexible valves) to a more accurate venous representation with a 3D cylindrical geometry obtained by 3D printing. In addition to the GPV experiments, we analysed the flow field developing in these geometries by using computational fluid dynamic simulations to develop a better understanding of the mechanisms behind DVT. ZS gratefully acknowledges financial support from the EPSRC through a studentship from the Sci-Phy-4-Health Centre for Doctoral Training (EP/L016346/1).

  7. POTENTIAL PATHOPHYSIOLOGICAL MECHANISMS OF ULTRAFINE PARTICLE TOXIC EFFECTS IN HUMANS

    Directory of Open Access Journals (Sweden)

    JASMINA JOVIĆ-STOŠIĆ

    2008-03-01

    Full Text Available Epidemiological and clinical studies suggested the association of the particulate matter ambient air pollution and the increased morbidity and mortality, mainly from respiratory and cardiovascular diseases. The size of particles has great influence on their toxicity, because it determines the site in the respiratory tract where they deposit. The most well established theory explaining the mechanisms behind the increased toxicity of ultrafine particles (UFP, < 0.1 µm is that it has to do with the increased surface area and/or the combination with the increased number of particles. Biological effects of UFP are also determined by their shape and chemical composition, so it is not possible to estimate their toxicity in a general way. General hypothesis suggested that exposure to inhaled particles induces pulmonary alveolar inflammation as a basic pathophysiological event, triggering release of various proinflammatory cytokines. Chronic inflammation is a very important underlying mechanism in the genesis of atherosclerosis and cardiovascular diseases. UFP can freely move through the circulation, but their effects on the secondary organs are not known yet, so more studies on recognizing toxicological endpoints of UFP are needed. Determination of UFP toxicity and the estimation of their internal and biologically active dose are necessary for the evidence based conclusions connecting air pollution by UFP and human diseases.

  8. Antidiabetic potentials of Momordica charantia: multiple mechanisms behind the effects.

    Science.gov (United States)

    Chaturvedi, Padmaja

    2012-02-01

    Momordica charantia fruits are used as a vegetable in many countries. From time immemorial, it has also been used for management of diabetes in the Ayurvedic and Chinese systems of medicine. Information regarding the standardization of this vegetable for its usage as an antidiabetic drug is scanty. There are many reports on its effects on glucose and lipid levels in diabetic animals and some in clinical trials. Reports regarding its mechanism of action are limited. So in the present review all the information is considered to produce some concrete findings on the mechanism behind its hypoglycemic and hypolipidemic effects. Studies have shown that M. charantia repairs damaged β-cells, increases insulin levels, and also enhance the sensitivity of insulin. It inhibits the absorption of glucose by inhibiting glucosidase and also suppresses the activity of disaccharidases in the intestine. It stimulates the synthesis and release of thyroid hormones and adiponectin and enhances the activity of AMP-activated protein kinase (AMPK). Effects of M. charantia like transport of glucose in the cells, transport of fatty acids in the mitochondria, modulation of insulin secretion, and elevation of levels of uncoupling proteins in adipose and skeletal muscles are similar to those of AMPK and thyroxine. Therefore it is proposed that effects of M. charantia on carbohydrate and fat metabolism are through thyroxine and AMPK.

  9. Raman analysis of DLC coated engine components with complex shape: Understanding wear mechanisms

    International Nuclear Information System (INIS)

    Jaoul, C.; Jarry, O.; Tristant, P.; Merle-Mejean, T.; Colas, M.; Dublanche-Tixier, C.; Jacquet, J.-M.

    2009-01-01

    Hydrogenated amorphous carbon (a-C:H) films were deposited on flat samples and engine components using an industrial scale reactor. Characterization of the coating allowed validating its application on engine parts due to high hardness (32 GPa) and high level of adhesion achieved using sublayers. The original approach of this work concerned the use of Raman analysis not only on flat samples after tribometer tests but also directly on coated engine parts with complex shape (like cam/follower system), in order to understand wear mechanisms occurring in motorsport engines. As wear could lead to a coating thickness decrease, a particular attention was paid on the Raman signal of the sublayers. Among the different values extracted from Raman spectrum to characterize structural organization, the value of G peak intensity appeared as a criterion of validity of analyses because it is directly linked to the remaining thickness of the a-C:H layer. For flat samples tested on ball-on-disc tribometer, structure of a-C:H film observed by Raman spectroscopy in the wear track remained stable in depth. Then, a-C:H coated engine components were studied before and after working in real conditions. Two different wear mechanisms were identified. The first one did not show any structural modification of the bulk a-C:H layer. In the second one, the high initial roughness of samples (R t = 1.15 μm) lead to coating delaminations after sliding. Massive graphitization which decreases drastically mechanical properties of the coatings was observed by Raman analyses on the contact area. The increase of the temperature on rough edges of the scratches could explain this graphitization.

  10. Features of Knowledge Building in Biology: Understanding Undergraduate Students' Ideas about Molecular Mechanisms.

    Science.gov (United States)

    Southard, Katelyn; Wince, Tyler; Meddleton, Shanice; Bolger, Molly S

    2016-01-01

    Research has suggested that teaching and learning in molecular and cellular biology (MCB) is difficult. We used a new lens to understand undergraduate reasoning about molecular mechanisms: the knowledge-integration approach to conceptual change. Knowledge integration is the dynamic process by which learners acquire new ideas, develop connections between ideas, and reorganize and restructure prior knowledge. Semistructured, clinical think-aloud interviews were conducted with introductory and upper-division MCB students. Interviews included a written conceptual assessment, a concept-mapping activity, and an opportunity to explain the biomechanisms of DNA replication, transcription, and translation. Student reasoning patterns were explored through mixed-method analyses. Results suggested that students must sort mechanistic entities into appropriate mental categories that reflect the nature of MCB mechanisms and that conflation between these categories is common. We also showed how connections between molecular mechanisms and their biological roles are part of building an integrated knowledge network as students develop expertise. We observed differences in the nature of connections between ideas related to different forms of reasoning. Finally, we provide a tentative model for MCB knowledge integration and suggest its implications for undergraduate learning. © 2016 K. Southard et al. CBE—Life Sciences Education © 2016 The American Society for Cell Biology. This article is distributed by The American Society for Cell Biology under license from the author(s). It is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  11. Cap buckling as a potential mechanism of atherosclerotic plaque vulnerability.

    Science.gov (United States)

    Abdelali, Maria; Reiter, Steven; Mongrain, Rosaire; Bertrand, Michel; L'Allier, Philippe L; Kritikou, Ekaterini A; Tardif, Jean-Claude

    2014-04-01

    Plaque rupture in atherosclerosis is the primary cause of potentially deadly coronary events, yet about 40% of ruptures occur away from the plaque cap shoulders and cannot be fully explained with the current biomechanical theories. Here, cap buckling is considered as a potential destabilizing factor which increases the propensity of the atherosclerotic plaque to rupture and which may also explain plaque failure away from the cap shoulders. To investigate this phenomenon, quasistatic 2D finite element simulations are performed, considering the salient geometrical and nonlinear material properties of diverse atherosclerotic plaques over the range of physiological loads. The numerical results indicate that buckling may displace the location of the peak von Mises stresses in the deflected caps. Plaque buckling, together with its deleterious effects is further observed experimentally in plaque caps using a physical model of deformable mock coronary arteries with fibroatheroma. Moreover, an analytical approach combining quasistatic equilibrium equations with the Navier-Bresse formulas is used to demonstrate the buckling potential of a simplified arched slender cap under intraluminal pressure and supported by foundations. This analysis shows that plaque caps - calcified, fibrotic or cellular - may buckle in specific undulated shapes once submitted to critical loads. Finally, a preliminary analysis of intravascular ultrasonography recordings of patients with atherosclerotic coronary arteries corroborates the numerical, experimental and theoretical findings and shows that various plaque caps buckle in vivo. By displacing the sites of high stresses in the plaque cap, buckling may explain the atherosclerotic plaque cap rupture at various locations, including cap shoulders. Copyright © 2013 Elsevier Ltd. All rights reserved.

  12. Curcumin and endometriosis: Review on potential roles and molecular mechanisms.

    Science.gov (United States)

    Arablou, Tahereh; Kolahdouz-Mohammadi, Roya

    2018-01-01

    Endometriosis, an estrogen-dependent inflammatory disease, is one of the most common chronic gynecological disorders affecting women in reproductive age. It is characterized by the presence of endometrial-like tissue outside the uterus. The exact pathophysiology of endometriosis is not still well-known, but the immune system and inflammation have been considered as pivotal factors in disease progression. Turmeric, an important spice all around the world, is obtained from the rhizomes of Curcuma longa, a member of the Zingiberaceae family. It has been used in the prevention and treatment of many diseases since ancient times. Curcumin is the principal polyphenol isolated from turmeric. Several evidences have shown the anti-inflammatory, antioxidant, anti-tumor, anti-angiogenesis, and anti-metastatic activities of curcumin. In this review, relevant articles on the effect of curcumin on endometriosis and possible molecular mechanisms are discussed. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  13. Understanding the mechanisms of thermal disintegrating treatment in the reduction of sludge production.

    Science.gov (United States)

    Camacho, P; Ginestet, P; Audic, J-M

    2005-01-01

    Among the technologies aimed at reducing sludge production, the combination of thermal treatment at 95 degrees C of sludge and the activated sludge process is a promising route. The feasibility of such a combined process is demonstrated (up to 60% sludge reduction) and the impacts of operating conditions on its efficiency are presented. Major emphasis was put on understanding the complex phenomena occurring within the thermal treatment: release and biodegradability of sludge organic matter, impact on the biological activity (decay, maintenance requirements, etc.). These effects were taken into account for the development of an ASM1-based model. Comparison between the modeling approach and experimental data (continuous and batch) showed that thermal treatment had three major issues partly explaining the reduction of sludge production: (i) a low release of organics; (ii) an immediate and reversible biological inactivation associated with additional maintenance energy requirements; and (iii) a potential inert production.

  14. Plant effects on soil denitrification - a review of potential mechanisms

    Science.gov (United States)

    Malique, Francois; Butterbach-Bahl, Klaus; Dannenmann, Michael

    2017-04-01

    Denitrification is a microbial process occurring in soils, both producing and consuming the potent greenhouse gas nitrous oxide (NO), competing for nitrate with plants and hydrological leaching pathways, removing nutrients and reactive nitrogen from the biosphere, and closing the global nitrogen cycle. Despite its obvious importance, denitrification remained among the least well quantified biogeochemical processes in soils. This is due to enormous methodological difficulties involved in the direct quantification of soil microbial denitrification rates (mainly with regard to the terminal product N2) and the denitrification nitrogen gas product ratios (NO:N2O:N2), Plants may affect denitrification through a myriad of mechanisms such as e.g., competition for nitrate and water, through oxygen consumption, by regulating litter quality and changing soil pH, and via the exudation of labile carbon or secondary plant compounds involved in shaping the rhizospheric microbial community. However, plant effects on denitrification so far hardly were quantified so that the actual extent of plant control on denitrification is largely unknown. Here, we summarize the current knowledge on mechanisms how plants can affect denitrification rates and N gas product ratios in soils at temporal scales from hours to days and years. We review earlier research to quantify plant effects on denitrification as well as critically discuss the limited methods currently available to quantify plant-soil-denitrifier interactions. Finally, we provide pointers to use plants as tools to manage denitrification, e.g. to improve N use efficiency in agricultural ecosystems and to minimize soil nitrous oxide emissions.

  15. Hunger and Satiety Mechanisms and Their Potential Exploitation in the Regulation of Food Intake.

    Science.gov (United States)

    Amin, Tehmina; Mercer, Julian G

    2016-03-01

    Effective strategies to combat recent rises in obesity levels are limited. The accumulation of excess body fat results when energy intake exceeds that expended. Energy balance is controlled by hypothalamic responses, but these can be overridden by hedonic/reward brain systems. This override, combined with unprecedented availability of cheap, energy-dense, palatable foods, may partly explain the increase in overweight and obesity. The complexity of the processes that regulate feeding behaviour has driven the need for further fundamental research. Full4Health is an EU-funded project conceived to advance our understanding of hunger and satiety mechanisms. Food intake has an impact on and is also affected by the gut-brain signalling which controls hunger and appetite. This review describes selected recent research from Full4Health and how new mechanistic findings could be exploited to adapt and control our physiological responses to food, potentially providing an alternative solution to addressing the global problems related to positive energy balance.

  16. Thymidylate Limitation Potentiates Cephalosporin Activity toward Enterococci via an Exopolysaccharide-Based Mechanism.

    Science.gov (United States)

    Hoff, Jessica S; Kristich, Christopher J

    2016-06-17

    Multidrug resistant enterococci are major causes of nosocomial infections. Prior therapy with cephalosporins increases the risk of developing an enterococcal infection due to the intrinsic resistance of enterococci to these antibiotics. While progress has been made toward understanding the genetic and biochemical mechanisms of cephalosporin resistance, available data indicate that as-yet-unidentified resistance factors must exist. Here, we describe results of a screen to identify small molecules capable of sensitizing enterococci to broad-spectrum cephalosporins. We found that both Enterococcus faecalis and Enterococcus faecium were sensitized to broad and expanded-spectrum cephalosporins when thymidylate production was impaired, whether by direct inhibition of thymidylate synthase, or by limiting production of cofactors required for its activity. Cephalosporin potentiation is the result of altered exopolysaccharide production due to reduced dTDP-glucose synthesis. Hence, exopolysaccharide production is a previously undescribed contributor to the intrinsic cephalosporin resistance of enterococci and serves as a new target for antienterococcal therapeutics.

  17. RFamide Peptides: Structure, Function, Mechanisms and Pharmaceutical Potential

    Directory of Open Access Journals (Sweden)

    Maria Findeisen

    2011-09-01

    Full Text Available Different neuropeptides, all containing a common carboxy-terminal RFamide sequence, have been characterized as ligands of the RFamide peptide receptor family. Currently, five subgroups have been characterized with respect to their N-terminal sequence and hence cover a wide pattern of biological functions, like important neuroendocrine, behavioral, sensory and automatic functions. The RFamide peptide receptor family represents a multiligand/multireceptor system, as many ligands are recognized by several GPCR subtypes within one family. Multireceptor systems are often susceptible to cross-reactions, as their numerous ligands are frequently closely related. In this review we focus on recent results in the field of structure-activity studies as well as mutational exploration of crucial positions within this GPCR system. The review summarizes the reported peptide analogs and recently developed small molecule ligands (agonists and antagonists to highlight the current understanding of the pharmacophoric elements, required for affinity and activity at the receptor family. Furthermore, we address the biological functions of the ligands and give an overview on their involvement in physiological processes. We provide insights in the knowledge for the design of highly selective ligands for single receptor subtypes to minimize cross-talk and to eliminate effects from interactions within the GPCR system. This will support the drug development of members of the RFamide family.

  18. Understanding the hydrolysis mechanism of ethyl acetate catalyzed by an aqueous molybdocene: a computational chemistry investigation.

    Science.gov (United States)

    Tílvez, Elkin; Cárdenas-Jirón, Gloria I; Menéndez, María I; López, Ramón

    2015-02-16

    , in general, the information reported here could be of interest in designing new catalysts and understanding the reaction mechanism of these and other metal-catalyzed hydrolysis reactions.

  19. Towards a better understanding of the therapeutic applications and corresponding mechanisms of action of honey.

    Science.gov (United States)

    Khan, Rifat Ullah; Naz, Shabana; Abudabos, Alaeldein M

    2017-12-01

    Honey is a bee-derived supersaturated solution composed of complex contents mainly glucose, fructose, amino acids, vitamins, and minerals. Composition of honey may vary due to the difference in nectar, season, geography, and storage condition. Honey has been used since times immemorial in folk medicine and has recently been rediscovered as an excellent therapeutic agent. In the past, honey was used for a variety of ailments without knowing the scientific background and active ingredients of honey. Today, honey has been scientifically proven for its antioxidant, regulation of glycemic response, antitumor, antimicrobial, anti-inflammatory, and cardiovascular potentiating agent. It can be used as a wound dressing and healing substance. Honey is different in color, flavor, sensory perception, and medical response. Apart from highlighting the nutritional facts of honey, we collected the finding of the published literature to know the mechanism of action of honey in different diseases. This review covers the composition, physiochemical characteristics, and some medical uses.

  20. Psychosomatic medicine in the 21st century: understanding mechanisms and barriers to utilization.

    Science.gov (United States)

    Wise, Thomas N; Balon, Richard

    2015-01-01

    The psychosomatic approach arose in antiquity as mankind looked for explanations for illness and death. With the rise of modern medicine, the links between emotions and medical conditions, such as cardiac disease and diabetes, were described by astute clinical observers, but the mechanisms for these conditions were based on correlation from observations rather than on experimental design. Psychoanalytic theory was often utilized to explain many common diseases. For example, peptic ulcer disease was blamed upon anger and stress, but scientific methodology discovered Helicobacter pylori to be the significant causal factor of this disease and resulted in the development of more effective treatments. Nevertheless emotional factors are still linked to disease states and morbidity; for example, depression is a risk factor for mortality following myocardial infarction. Advances in neuroscience demonstrate that the reduction of telomere length by anxiety and stress leads to more rapid aging and potential disease vulnerability. Thus, neuroscientific probes may allow for the elucidation of psychosomatic mechanisms. Sadly, clinical barriers, in terms of time pressure upon physicians and the current separation of mental health services from primary care settings, continue the dualistic treatment of many conditions where psychological factors are important. It is not clear whether a mandate for the integration of behavioral health into primary care will remedy this partition and finally maximize a psychosomatic approach to medical care. © 2015 S. Karger AG, Basel.

  1. The Effects of Calorie Restriction in Depression and Potential Mechanisms

    Science.gov (United States)

    Zhang, Yifan; Liu, Changhong; Zhao, Yinghao; Zhang, Xingyi; Li, Bingjin; Cui, Ranji

    2015-01-01

    Depression, also called major depressive disorder, is a neuropsychiatric disorder jeopardizing an increasing number of the population worldwide. To date, a large number of studies have devoted great attention to this problematic condition and raised several hypotheses of depression. Based on these theories, many antidepressant drugs were developed for the treatment of depression. Yet, the depressed patients are often refractory to the antidepressant therapies. Recently, increasing experimental evidences demonstrated the effects of calorie restriction in neuroendocrine system and in depression. Both basic and clinical investigations indicated that short-term calorie restriction might induce an antidepressant efficacy in depression, providing a novel avenue for treatment. Molecular basis underlying the antidepressant actions of calorie restriction might involve multiple physiological processes, primarily including orexin signaling activation, increased CREB phosphorylation and neurotrophic effects, release of endorphin and ketone production. However, the effects of chronic calorie restriction were quite controversial, in the cases that it often resulted in the long-term detrimental effects via inhibiting the function of 5-HT system and decreasing leptin levels. Here we review such dual effects of calorie restriction in depression and potential molecular basis behind these effects, especially focusing on antidepressant effects. PMID:26412073

  2. Potential mechanism for Calvados-related oesophageal cancer.

    Science.gov (United States)

    Linderborg, Klas; Joly, Jean Pierre; Visapää, Jukka-Pekka; Salaspuro, Mikko

    2008-02-01

    The old Normandian habit of consumption of hot Calvados is associated with an increased risk of oesophageal cancer compared to other alcoholic beverages. The role of alcohol consumption in the risk of oesophageal cancer is well established. The first metabolite of alcohol, acetaldehyde is a potential local carcinogen in humans. Accordingly, different acetaldehyde concentrations in different beverages could account for some of the variations in cancer risk with regard to the type of alcoholic beverage. Eighteen samples of farm-made Calvados were collected in Normandy. Samples of commercially available beverages were purchased, including factory-made Calvados, other spirits, wines, beer and cider. The samples were analysed gas-chromatically for acetaldehyde and ethanol concentrations. All results are expressed as mean+/-SD. The mean acetaldehyde concentration of all Calvados samples (1781+/-861 microM, n =25) differed highly significantly (pcognac had the highest mean acetaldehyde concentration of the measured beverages. The high concentration of acetaldehyde combined with possible effects of the high temperature at which Calvados is consumed could account for the increased risk of Calvados-related oesophageal cancer.

  3. Understanding the molecular mechanism of pulse current charging for stable lithium-metal batteries.

    Science.gov (United States)

    Li, Qi; Tan, Shen; Li, Linlin; Lu, Yingying; He, Yi

    2017-07-01

    High energy and safe electrochemical storage are critical components in multiple emerging fields of technologies. Rechargeable lithium-metal batteries are considered to be promising alternatives for current lithium-ion batteries, leading to as much as a 10-fold improvement in anode storage capacity (from 372 to 3860 mAh g -1 ). One of the major challenges for commercializing lithium-metal batteries is the reliability and safety issue, which is often associated with uneven lithium electrodeposition (lithium dendrites) during the charging stage of the battery cycling process. We report that stable lithium-metal batteries can be achieved by simply charging cells with square-wave pulse current. We investigated the effects of charging period and frequency as well as the mechanisms that govern this process at the molecular level. Molecular simulations were performed to study the diffusion and the solvation structure of lithium cations (Li + ) in bulk electrolyte. The model predicts that loose association between cations and anions can enhance the transport of Li + and eventually stabilize the lithium electrodeposition. We also performed galvanostatic measurements to evaluate the cycling behavior and cell lifetime under pulsed electric field and found that the cell lifetime can be more than doubled using certain pulse current waveforms. Both experimental and simulation results demonstrate that the effectiveness of pulse current charging on dendrite suppression can be optimized by choosing proper time- and frequency-dependent pulses. This work provides a molecular basis for understanding the mechanisms of pulse current charging to mitigating lithium dendrites and designing pulse current waveforms for stable lithium-metal batteries.

  4. A Study to Understand the Potential Vulnerabilities to the Foundations of Historic Structures in Coastal Areas

    Science.gov (United States)

    Hall, C. L.; Curran, B.; Jefferson, M.; Routhier, M.; Mulukutla, G. K.

    2011-12-01

    Sea level rise, one of the most important manifestations of climate change is expected to result in increased coastal erosion and storm surge flooding. This work reports on a project undertaken to assess the vulnerability of foundations of historic structures in coastal areas to the potential consequences from climate change resulting from increased storm surge flooding. Foundations of historic buildings are especially vulnerable to the seepage and ground water intrusion. Many historic structures themselves are used to house valuable historic collections making it all the important to preserve and protect these structures. Data collected from a field subsurface geophysical survey, geospatial field survey, and a simulation to understand the hydrological conditions of the site useful to build an understanding of threats to foundations of historic structures located on the coast. The study site chosen for this project is the Strawbery Banke Living History Museum, in Portsmouth, NH. Located very close to the banks of the Piscataqua River at its meeting point with the Atlantic Ocean, it consists of many buildings of historical importance dating as far back as 1690. Upstream of the river is the tidal estuary system, the Great Bay which itself is formed by a confluence of seven major rivers, making it a highly dynamic, tide-dominated body of fresh and saltwater. Strawbery Banke is representative of historic structures, located on the Northeastern coast of the US, that will likely be impacted by climate change. The primary threat to the sub-structures for the site is Puddle Dock; a tidal inlet , that lies at the heart of the facility, that once provided direct river access to Strawbery Banke (and since filled around 1900). Results from the long term deployment of in -situ water level loggers in test wells, temperature and relative humidity sensors, and a ground penetration radar survey of the Puddle Dock, along with the detailed fine-scale elevation survey of the site

  5. Understanding creep in sandstone reservoirs - theoretical deformation mechanism maps for pressure solution in granular materials

    Science.gov (United States)

    Hangx, Suzanne; Spiers, Christopher

    2014-05-01

    Subsurface exploitation of the Earth's natural resources removes the natural system from its chemical and physical equilibrium. As such, groundwater extraction and hydrocarbon production from subsurface reservoirs frequently causes surface subsidence and induces (micro)seismicity. These effects are not only a problem in onshore (e.g. Groningen, the Netherlands) and offshore hydrocarbon fields (e.g. Ekofisk, Norway), but also in urban areas with extensive groundwater pumping (e.g. Venice, Italy). It is known that fluid extraction inevitably leads to (poro)elastic compaction of reservoirs, hence subsidence and occasional fault reactivation, and causes significant technical, economic and ecological impact. However, such effects often exceed what is expected from purely elastic reservoir behaviour and may continue long after exploitation has ceased. This is most likely due to time-dependent compaction, or 'creep deformation', of such reservoirs, driven by the reduction in pore fluid pressure compared with the rock overburden. Given the societal and ecological impact of surface subsidence, as well as the current interest in developing geothermal energy and unconventional gas resources in densely populated areas, there is much need for obtaining better quantitative understanding of creep in sediments to improve the predictability of the impact of geo-energy and groundwater production. The key problem in developing a reliable, quantitative description of the creep behaviour of sediments, such as sands and sandstones, is that the operative deformation mechanisms are poorly known and poorly quantified. While grain-scale brittle fracturing plus intergranular sliding play an important role in the early stages of compaction, these time-independent, brittle-frictional processes give way to compaction creep on longer time-scales. Thermally-activated mass transfer processes, like pressure solution, can cause creep via dissolution of material at stressed grain contacts, grain

  6. Understanding the mechanisms of secondary nucleation for protein aggregation: an analytical approach

    Science.gov (United States)

    Michaels, Thomas; Knowles, Tuomas P. J.

    2013-03-01

    Filamentous protein self-assembly is a general type of behaviour accessible to a wide range of different polypeptide sequences. This phenomenon underlies key molecular events both in normal and aberrant biology, but a general theory of the crucial nucleation steps that govern this process has remained elusive. In this talk we discuss our attempts to provide a general description of secondary nucleation in filamentous protein assembly based on the Becker-Döring kinetic scheme to describe cluster-catalytic effects. This systematic procedure allows extracting low-dimensional systems of equations out of the full kinetic model, in a master equation formalism typically consisting of infinitely many coupled non-linear equations. Using this procedure, we propose and discuss various mechanisms that can underlie the secondary nucleation process. Using data curve-fitting and analysis we show that the addition of a monomer to heterogeneous nuclei is effectively irreversible and discuss the implications of our framework for the more general understanding of the physics of multi-step nucleation phenomena in nature.

  7. Understanding the mechanisms of sickle cell disease by simulations with a discrete particle model

    Science.gov (United States)

    Hui, Katrina; Lin, Guang; Pan, Wenxiao

    2013-01-01

    Sickle cell disease (SCD) is an inherited blood disorder characterized by rigid, sickle-shaped red blood cells (RBCs). Because of their rigidity and shape, sickle cells can get stuck in smaller blood vessels, causing blockages and depriving oxygen to tissues. This study develops and applies mathematical models to better understand the mechanism of SCD. Two-dimensional models of RBCs and blood vessels have been constructed by representing them as discrete particles interacting with different forces. The nonlinear, elastic property of healthy RBCs could be adequately reproduced using a cosine angle bending force and a worm-like chain spring force. With the ability to deform, RBCs can squeeze through narrow blood vessels. In modeling sickle cells as rigid bodies and applying repelling and friction forces from the blood vessel, this study shows that geometrical factors (dimensions of the sickle cell and blood vessels) as well as rigidity and adhesiveness of the sickle cell all play an important role in determining how, and if, sickle cells become trapped within narrow blood capillaries. With lack of data to validate the model, this study primarily provides a sensitivity analysis of factors influencing sickle cell occlusion and identified critical data to support future modeling.

  8. Potentials of Industrie 4.0 and Machine Learning for Mechanical Joining

    OpenAIRE

    Jäckel, Mathias

    2017-01-01

    -Sensitivity analysis of the influence of component properties and joining parameters on the joining result for self-pierce riveting -Possibilities to link mechanical joining technologies with the automotive process chain for quality and flexibility improvements -Potential of using machine learning to reduce automotive product development cycles in relation to mechanical joining -Datamining for machine learning at mechanical joining

  9. Current understanding of the driving mechanisms for spatiotemporal variations of atmospheric speciated mercury: a review

    Directory of Open Access Journals (Sweden)

    H. Mao

    2016-10-01

    Full Text Available Atmospheric mercury (Hg is a global pollutant and thought to be the main source of mercury in oceanic and remote terrestrial systems, where it becomes methylated and bioavailable; hence, atmospheric mercury pollution has global consequences for both human and ecosystem health. Understanding of spatial and temporal variations of atmospheric speciated mercury can advance our knowledge of mercury cycling in various environments. This review summarized spatiotemporal variations of total gaseous mercury or gaseous elemental mercury (TGM/GEM, gaseous oxidized mercury (GOM, and particulate-bound mercury (PBM in various environments including oceans, continents, high elevation, the free troposphere, and low to high latitudes. In the marine boundary layer (MBL, the oxidation of GEM was generally thought to drive the diurnal and seasonal variations of TGM/GEM and GOM in most oceanic regions, leading to lower GEM and higher GOM from noon to afternoon and higher GEM during winter and higher GOM during spring–summer. At continental sites, the driving mechanisms of TGM/GEM diurnal patterns included surface and local emissions, boundary layer dynamics, GEM oxidation, and for high-elevation sites mountain–valley winds, while oxidation of GEM and entrainment of free tropospheric air appeared to control the diurnal patterns of GOM. No pronounced diurnal variation was found for Tekran measured PBM at MBL and continental sites. Seasonal variations in TGM/GEM at continental sites were attributed to increased winter combustion and summertime surface emissions, and monsoons in Asia, while those in GOM were controlled by GEM oxidation, free tropospheric transport, anthropogenic emissions, and wet deposition. Increased PBM at continental sites during winter was primarily due to local/regional coal and wood combustion emissions. Long-term TGM measurements from the MBL and continental sites indicated an overall declining trend. Limited measurements suggested TGM

  10. Mechanisms of radiation interaction with DNA: Potential implications for radiation protection

    Energy Technology Data Exchange (ETDEWEB)

    1988-01-01

    The Office of Health and Environmental Research (OHER) of the US Department of Energy conducts a broad multidisciplinary research program which includes basic biophysics, biophysical chemistry, molecular and cellular biology as well as experimental animal studies and opportunistic human studies. This research is directed at understanding how low levels of radiation of various qualities produce the spectrum of biological effects that are seen for such exposures. This workshop was entitled ''Mechanisms of Radiation Interaction with DNA: Potential Implications for Radiation Protection.'' It ws jointly sponsored by the Department of Energy and the Commission of European Communities. The aim of the workshop was to review the base of knowledge in the area of mechanisms of radiation action at the DNA level, and to explore ways in which this information can be applied to the development of scientifically sound concepts and procedures for use in the field of radiation protection. The overview of research provided by this multidisciplinary group will be helpful to the Office in program planning. This report includes a summary of the presentations, extended abstracts, the meeting agenda, research recommendations, and a list of participants. Individual papers are processed separately for the data base.

  11. Psychological Stress and skin aging: a review of possible mechanisms and potential therapies.

    Science.gov (United States)

    Dunn, Jeffrey H; Koo, John

    2013-06-15

    The link between psychological stress and aging is intuitive although the underlying mechanisms are not well defined. Evidence suggests that chronic psychological stress stimulates the autonomic nervous system, renin-angiotensin system, and the hypothalamic-pituitary-adrenal axis when the body attempts to resolve perceived threats to homeostasis. Prolonged activation of these pathways can result in chronic immune dysfunction, increased production of reactive oxygen species, and DNA damage, which are known to contribute to the again of skin and other tissues. Despite the lack of conclusive evidence directly linking psychological stress to skin aging, mechanisms by which stress leads to immune dysfunction, oxidative radicals, and ultimately DNA damage via neuronal, endocrine, and immune modulation may present a possible intervention for skin aging. In addition to the wide array of anti-oxidant therapies being developed to combat aging, the topical use of beta-blockers such as timolol, angiotensin receptor blockers such as valsartan, glucocorticoid blockers such as mifepristone, and cholinergic modulators including botulinum toxin, might be potential therapeutic strategies to prevent skin aging. Given the current understanding of these pathways, it would be premature to utilize such modalities for prevention of skin aging at this time, but future research into this type of topical pharmacologic anti-aging intervention may be promising.

  12. Mechanisms of radiation interaction with DNA: Potential implications for radiation protection

    International Nuclear Information System (INIS)

    1988-01-01

    The Office of Health and Environmental Research (OHER) of the US Department of Energy conducts a broad multidisciplinary research program which includes basic biophysics, biophysical chemistry, molecular and cellular biology as well as experimental animal studies and opportunistic human studies. This research is directed at understanding how low levels of radiation of various qualities produce the spectrum of biological effects that are seen for such exposures. This workshop was entitled ''Mechanisms of Radiation Interaction with DNA: Potential Implications for Radiation Protection.'' It ws jointly sponsored by the Department of Energy and the Commission of European Communities. The aim of the workshop was to review the base of knowledge in the area of mechanisms of radiation action at the DNA level, and to explore ways in which this information can be applied to the development of scientifically sound concepts and procedures for use in the field of radiation protection. The overview of research provided by this multidisciplinary group will be helpful to the Office in program planning. This report includes a summary of the presentations, extended abstracts, the meeting agenda, research recommendations, and a list of participants. Individual papers are processed separately for the data base

  13. Understanding and Exploration of the Biomineralization Mechanisms for the Controllable Synthesis of Nanomaterials

    Science.gov (United States)

    Xiao, Junwu

    This thesis is mainly concerned with understanding the biomineralization mechanisms, and further extrapolating them for the controllable synthesis of transition metal compound nanomaterials on graphene sheets for energy storage applications in electrochemical capacitors and lithium ion batteries (LIB). Firstly, we have studied the mimetic biomineralization process of CaCO 3 on a stearic acid or 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) Langmuir monolayer at the air-water interface by in-situ Brewster angle microscopy (BAM) and ex-situ electron microscopy. Amorphous calcium carbonate (ACC) precursors are directly nucleated from solvated ions prior to the crystal nuclei on a Langmuir monolayer. On a DPPC monolayer, numerous fresh ACC nanoparticles heterogeneously and continuously nucleated at the air-water interface are transformed into the metastable vaterite nanocrystals. Driven by the trend to decrease surface energy, the vaterite nanocrystals self-aggregate and grow into the loose-packed hollow ellipsoidal vaterite polycrystals. These nanocrystals in vaterite polycrystals are then gradually orientated in the same direction to evolve into tight-packed ellipsoidal mesocrystals. As the crystallization time is further increased, the metastable vaterite mesocrystals are eventually transformed into the most thermodynamically stable calcite crystals. Secondly, organic and inorganic additives control over the shapes, sizes and phases of inorganic nanocrystals and arrange them into ordered structures from amorphous precursors in the organisms. This interesting phenomenon has galvanized many attempts to mimic the biomineralization process for synthesizing novel materials. We have studied the crystallization processes from small citrate molecules stabilized ACC precursors under cetyltrimethyl ammonium bromide (CTAB) micellar structures. Amorphous precursors, with a hydrated and disordered structure, are easily transformed and molded into CaCO 3 crystals with

  14. MECHANISMS OF GROWTH AND TRANSFORMATION OF HUMAN AND INTELLECTUAL POTENTIALS IN CORPORATION OF KNOWLEDGE ECONOMY

    OpenAIRE

    Lanskaya D. V.

    2013-01-01

    The article considers the mechanisms of growth, transformation of human and intellectual potentials in the corporation capitals, and also the mechanisms of fixing of their carriers in a corporation for the purpose of ensuring growth of competitive force of corporation of knowledge economy; in particular, we have investigated basic mechanisms of interaction of owners of human and intellectual capitals with a vertical of the economic power of corporation and the mechanism of an intellectual ren...

  15. ARHGEF9 mutations in epileptic encephalopathy/intellectual disability: toward understanding the mechanism underlying phenotypic variation.

    Science.gov (United States)

    Wang, Jing-Yang; Zhou, Peng; Wang, Jie; Tang, Bin; Su, Tao; Liu, Xiao-Rong; Li, Bing-Mei; Meng, Heng; Shi, Yi-Wu; Yi, Yong-Hong; He, Na; Liao, Wei-Ping

    2018-01-01

    ARHGEF9 resides on Xq11.1 and encodes collybistin, which is crucial in gephyrin clustering and GABA A receptor localization. ARHGEF9 mutations have been identified in patients with heterogeneous phenotypes, including epilepsy of variable severity and intellectual disability. However, the mechanism underlying phenotype variation is unknown. Using next-generation sequencing, we identified a novel mutation, c.868C > T/p.R290C, which co-segregated with epileptic encephalopathy, and validated its association with epileptic encephalopathy. Further analysis revealed that all ARHGEF9 mutations were associated with intellectual disability, suggesting its critical role in psychomotor development. Three missense mutations in the PH domain were not associated with epilepsy, suggesting that the co-occurrence of epilepsy depends on the affected functional domains. Missense mutations with severe molecular alteration in the DH domain, or located in the DH-gephyrin binding region, or adjacent to the SH3-NL2 binding site were associated with severe epilepsy, implying that the clinical severity was potentially determined by alteration of molecular structure and location of mutations. Male patients with ARHGEF9 mutations presented more severe phenotypes than female patients, which suggests a gene-dose effect and supports the pathogenic role of ARHGEF9 mutations. This study highlights the role of molecular alteration in phenotype expression and facilitates evaluation of the pathogenicity of ARHGEF9 mutations in clinical practice.

  16. Understanding physiological and degenerative natural vision mechanisms to define contrast and contour operators.

    Directory of Open Access Journals (Sweden)

    Jacques Demongeot

    Full Text Available BACKGROUND: Dynamical systems like neural networks based on lateral inhibition have a large field of applications in image processing, robotics and morphogenesis modeling. In this paper, we will propose some examples of dynamical flows used in image contrasting and contouring. METHODOLOGY: First we present the physiological basis of the retina function by showing the role of the lateral inhibition in the optical illusions and pathologic processes generation. Then, based on these biological considerations about the real vision mechanisms, we study an enhancement method for contrasting medical images, using either a discrete neural network approach, or its continuous version, i.e. a non-isotropic diffusion reaction partial differential system. Following this, we introduce other continuous operators based on similar biomimetic approaches: a chemotactic contrasting method, a viability contouring algorithm and an attentional focus operator. Then, we introduce the new notion of mixed potential Hamiltonian flows; we compare it with the watershed method and we use it for contouring. CONCLUSIONS: We conclude by showing the utility of these biomimetic methods with some examples of application in medical imaging and computed assisted surgery.

  17. The low FODMAP diet: recent advances in understanding its mechanisms and efficacy in IBS.

    Science.gov (United States)

    Staudacher, Heidi M; Whelan, Kevin

    2017-08-01

    There is an intensifying interest in the interaction between diet and the functional GI symptoms experienced in IBS. Recent studies have used MRI to demonstrate that short-chain fermentable carbohydrates increase small intestinal water volume and colonic gas production that, in those with visceral hypersensitivity, induces functional GI symptoms. Dietary restriction of short-chain fermentable carbohydrates (the low fermentable oligosaccharide, disaccharide, monosaccharide and polyol (FODMAP) diet) is now increasingly used in the clinical setting. Initial research evaluating the efficacy of the low FODMAP diet was limited by retrospective study design and lack of comparator groups, but more recently well-designed clinical trials have been published. There are currently at least 10 randomised controlled trials or randomised comparative trials showing the low FODMAP diet leads to clinical response in 50%-80% of patients with IBS, in particular with improvements in bloating, flatulence, diarrhoea and global symptoms. However, in conjunction with the beneficial clinical impact, recent studies have also demonstrated that the low FODMAP diet leads to profound changes in the microbiota and metabolome, the duration and clinical relevance of which are as yet unknown. This review aims to present recent advances in the understanding of the mechanisms by which the low FODMAP diet impacts on symptoms in IBS, recent evidence for its efficacy, current findings regarding the consequences of the diet on the microbiome and recommendations for areas for future research. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  18. World Biofuels Production Potential Understanding the Challenges to Meeting the U.S. Renewable Fuel Standard

    Energy Technology Data Exchange (ETDEWEB)

    Sastri, B.; Lee, A.

    2008-09-15

    This study by the U.S. Department of Energy (DOE) estimates the worldwide potential to produce biofuels including biofuels for export. It was undertaken to improve our understanding of the potential for imported biofuels to satisfy the requirements of Title II of the 2007 Energy Independence and Security Act (EISA) in the coming decades. Many other countries biofuels production and policies are expanding as rapidly as ours. Therefore, we modeled a detailed and up-to-date representation of the amount of biofuel feedstocks that are being and can be grown, current and future biofuels production capacity, and other factors relevant to the economic competitiveness of worldwide biofuels production, use, and trade. The Oak Ridge National Laboratory (ORNL) identified and prepared feedstock data for countries that were likely to be significant exporters of biofuels to the U.S. The National Renewable Energy Laboratory (NREL) calculated conversion costs by conducting material flow analyses and technology assessments on biofuels technologies. Brookhaven National Laboratory (BNL) integrated the country specific feedstock estimates and conversion costs into the global Energy Technology Perspectives (ETP) MARKAL (MARKet ALlocation) model. The model uses least-cost optimization to project the future state of the global energy system in five year increments. World biofuels production was assessed over the 2010 to 2030 timeframe using scenarios covering a range U.S. policies (tax credits, tariffs, and regulations), as well as oil prices, feedstock availability, and a global CO{sub 2} price. All scenarios include the full implementation of existing U.S. and selected other countries biofuels policies (Table 4). For the U.S., the most important policy is the EISA Title II Renewable Fuel Standard (RFS). It progressively increases the required volumes of renewable fuel used in motor vehicles (Appendix B). The RFS requires 36 billion (B) gallons (gal) per year of renewable fuels by 2022

  19. Application potential of grapefruit peel as dye sorbent: Kinetics, equilibrium and mechanism of crystal violet adsorption

    International Nuclear Information System (INIS)

    Saeed, Asma; Sharif, Mehwish; Iqbal, Muhammad

    2010-01-01

    This study reports the sorption of crystal violet (CV) dye by grapefruit peel (GFP), which has application potential in the remediation of dye-contaminated wastewaters using a solid waste generated by the citrus fruit juice industry. Batch adsorption of CV was conducted to evaluate the effect of initial pH, contact time, temperature, initial dye concentration, GFP adsorbent dose, and removal of the adsorbate CV dye from aqueous solution to understand the mechanism of sorption involved. Sorption equilibrium reached rapidly with 96% CV removal in 60 min. Fit of the sorption experimental data was tested on the pseudo-first and pseudo-second-order kinetics mathematical equations, which was noted to follow the pseudo-second-order kinetics better, with coefficient of correlation ≥0.992. The equilibrium process was well described by the Langmuir isotherm model, with maximum sorption capacity of 254.16 mg g -1 . The GFP was regenerated using 1 M NaOH, with up to 98.25% recovery of CV and could be reused as a dye sorbent in repeated cycles. GFP was also shown to be highly effective in removing CV from aqueous solution in continuous-flow fixed-bed column reactors. The study shows that GFP has the potential of application as an efficient sorbent for the removal of CV from aqueous solutions.

  20. Dynamical symmetry as a tool to understanding properties of supersymmetric partner potentials. Example of so(2,1) symmetry

    International Nuclear Information System (INIS)

    Wehrhahn, R.F.; Cooper, I.L.

    1992-05-01

    Analysis of the dynamical symmetry of a system is used to predict properties arising from its supersymmetric quantum mechanical treatment. Two applications of the so(2,1) algebra, the Coulomb potential and Morse oscillator potential which display different structure with respect to the dynamical symmetry, are studied. This difference is shown to be responsible for the behaviour of the respective supersymmetric partner potentials. (orig.)

  1. Properties and ionic mechanisms of action potential adaptation, restitution, and accommodation in canine epicardium

    Science.gov (United States)

    Decker, Keith F.; Heijman, Jordi; Silva, Jonathan R.; Hund, Thomas J.; Rudy, Yoram

    2009-01-01

    Computational models of cardiac myocytes are important tools for understanding ionic mechanisms of arrhythmia. This work presents a new model of the canine epicardial myocyte that reproduces a wide range of experimentally observed rate-dependent behaviors in cardiac cell and tissue, including action potential (AP) duration (APD) adaptation, restitution, and accommodation. Model behavior depends on updated formulations for the 4-aminopyridine-sensitive transient outward current (Ito1), the slow component of the delayed rectifier K+ current (IKs), the L-type Ca2+ channel current (ICa,L), and the Na+-K+ pump current (INaK) fit to data from canine ventricular myocytes. We found that Ito1 plays a limited role in potentiating peak ICa,L and sarcoplasmic reticulum Ca2+ release for propagated APs but modulates the time course of APD restitution. IKs plays an important role in APD shortening at short diastolic intervals, despite a limited role in AP repolarization at longer cycle lengths. In addition, we found that ICa,L plays a critical role in APD accommodation and rate dependence of APD restitution. Ca2+ entry via ICa,L at fast rate drives increased Na+-Ca2+ exchanger Ca2+ extrusion and Na+ entry, which in turn increases Na+ extrusion via outward INaK. APD accommodation results from this increased outward INaK. Our simulation results provide valuable insight into the mechanistic basis of rate-dependent phenomena important for determining the heart's response to rapid and irregular pacing rates (e.g., arrhythmia). Accurate simulation of rate-dependent phenomena and increased understanding of their mechanistic basis will lead to more realistic multicellular simulations of arrhythmia and identification of molecular therapeutic targets. PMID:19168720

  2. Understanding the mechanisms that change the conductivity of damaged ITO-coated polymeric films: A micro-mechanical investigation

    KAUST Repository

    Nasr Saleh, Mohamed

    2014-11-01

    Degradation from mechanical loading of transparent electrodes made of indium tin oxide (ITO) endangers the integrity of any material based on these electrodes, including flexible organic solar cells. However, how different schemes of degradation change the conductivity of ITO devices remains unclear. We propose a systematic micro-mechanics-based approach to clarify the relationship between degradation and changes in electrical resistance. By comparing experimentally measured channel crack densities to changes in electrical resistance returned by the different micro-mechanical schemes, we highlight the key role played by the residual conductivity in the interface between the ITO electrode and its substrate after delamination. We demonstrate that channel cracking alone does not explain the experimental observations. Our results indicate that delamination has to take place between the ITO electrode and the substrate layers and that the residual conductivity of this delaminated interface plays a major role in changes in electrical resistance of the degraded device. © 2014 Elsevier B.V.

  3. Understanding the mechanism of DNA deactivation in ion therapy of cancer cells: hydrogen peroxide action*

    Science.gov (United States)

    Piatnytskyi, Dmytro V.; Zdorevskyi, Oleksiy O.; Perepelytsya, Sergiy M.; Volkov, Sergey N.

    2015-11-01

    Changes in the medium of biological cells under ion beam irradiation has been considered as a possible cause of cell function disruption in the living body. The interaction of hydrogen peroxide, a long-lived molecular product of water radiolysis, with active sites of DNA macromolecule was studied, and the formation of stable DNA-peroxide complexes was considered. The phosphate groups of the macromolecule backbone were picked out among the atomic groups of DNA double helix as a probable target for interaction with hydrogen peroxide molecules. Complexes consisting of combinations including: the DNA phosphate group, H2O2 and H2O molecules, and Na+ counterion, were considered. The counterions have been taken into consideration insofar as under the natural conditions they neutralise DNA sugar-phosphate backbone. The energy of the complexes have been determined by considering the electrostatic and the Van der Waals interactions within the framework of atom-atom potential functions. As a result, the stability of various configurations of molecular complexes was estimated. It was shown that DNA phosphate groups and counterions can form stable complexes with hydrogen peroxide molecules, which are as stable as the complexes with water molecules. It has been demonstrated that the formation of stable complexes of H2O2-Na+-PO4- may be detected experimentally by observing specific vibrations in the low-frequency Raman spectra. The interaction of H2O2 molecule with phosphate group of the double helix backbone can disrupt DNA biological function and induce the deactivation of the cell genetic apparatus. Thus, the production of hydrogen peroxide molecules in the nucleus of living cells can be considered as an additional mechanism by which high-energy ion beams destroy tumour cells during ion beam therapy. Contribution to the Topical Issue "COST Action Nano-IBCT: Nano-scale Processes Behind Ion-Beam Cancer Therapy", edited by Andrey Solov'yov, Nigel Mason, Gustavo García, Eugene

  4. Laboratory experiments for understanding mechanical properties of fractured granite under supercritical conditions

    Science.gov (United States)

    Kitamura, M.; Takahashi, M.; Takagi, K.; Hirano, N.; Tsuchiya, N.

    2017-12-01

    To extract geothermal energy effectively and safely from magma and/or adjacent hot rock, we need to tackle many issues which require new technology development, such as a technique to control a risk from induced-earthquakes. On a development of induced-earthquake mitigation technology, it is required to understand roles of factors on occurrences of the induced-earthquake (e.g., strength, crack density, and fluid-rock reaction) and their intercorrelations (e.g., Asanuma et al., 2012). Our purpose of this series of experiments is to clarify a relationship between the rock strength and the crack density under supercritical conditions. We conducted triaxial deformation test on intact granite rock strength under high-temperature (250 - 750°C), high-pressure (104 MPa) condition at a constant load velocity (0.1 μm/sec) using a gas-rig at AIST. We used Oshima granite, which has initially stress drop became smaller at higher temperature. Young's modulus increased with decreasing the temperature from 32.3 GPa at 750°C to 57.4 GPa at 250°C. At 400 °C, the stress drop accelerated the deformation with 98 times faster velocity than that at load-point. In contrast, at 650°C and 750°C, the velocity during stress drop kept the same order of the load-point velocity. Therefore, the deformation mechanism may start to be changed from brittle to ductile when the temperature exceeds 650°C. Highly dense cracked granite specimens were formed by a rapid decompression test (RDT) using an autoclave settled at Tohoku University (Hirano et al., 2016JpGU), caused by a reduction of fluid pressure within 1-2 sec from vapor/supercritical state (10 - 48 MPa, 550 °C) to ambient pressure. The specimens after RDT show numerous microcracks on X-ray CT images. The RDT imposed the porosity increasing towards 3.75 % and Vp and Vs decreasing towards 1.37±0.52 km/s and 0.97±0.25 km/s. The Poisson's ratio shows the negative values in dry and 0.5 in wet. In the meeting, we will present results of

  5. Exploring potentials of sense-making theory for understanding social processes in public hearing

    DEFF Research Database (Denmark)

    Lyhne, Ivar

    This paper has point of departure in a planning process on energy infrastructure in Denmark and focuses on a particular public hearing meeting characterised by trenchant opposition and distrust to the authorities among the public. It points at the need to understand the interaction between author...... of such a public meeting and the importance of trust and openness in the social processes in a public hearing....... authorities and the public in such planning often characterised by conflict. A sense-making framework is developed based on Karl Weick's theory to investigate how participants at the meeting change their understanding aspects like other actors' opinions and the infrastructure project. Through interviews...

  6. A new application of the phase-field method for understanding the mechanisms of nuclear architecture reorganization.

    Science.gov (United States)

    Lee, S Seirin; Tashiro, S; Awazu, A; Kobayashi, R

    2017-01-01

    Specific features of nuclear architecture are important for the functional organization of the nucleus, and chromatin consists of two forms, heterochromatin and euchromatin. Conventional nuclear architecture is observed when heterochromatin is enriched at nuclear periphery, and it represents the primary structure in the majority of eukaryotic cells, including the rod cells of diurnal mammals. In contrast to this, inverted nuclear architecture is observed when the heterochromatin is distributed at the center of the nucleus, which occurs in the rod cells of nocturnal mammals. The inverted architecture found in the rod cells of the adult mouse is formed through the reorganization of conventional architecture during terminal differentiation. Although a previous experimental approach has demonstrated the relationship between these two nuclear architecture types at the molecular level, the mechanisms underlying long-range reorganization processes remain unknown. The details of nuclear structures and their spatial and temporal dynamics remain to be elucidated. Therefore, a comprehensive approach, using mathematical modeling, is required, in order to address these questions. Here, we propose a new mathematical approach to the understanding of nuclear architecture dynamics using the phase-field method. We successfully recreated the process of nuclear architecture reorganization, and showed that it is robustly induced by physical features, independent of a specific genotype. Our study demonstrates the potential of phase-field method application in the life science fields.

  7. Contribution of proteomics of Leishmania spp. to the understanding of differentiation, drug resistance mechanisms, vaccine and drug development.

    Science.gov (United States)

    Paape, Daniel; Aebischer, Toni

    2011-08-24

    Leishmania spp., protozoan parasites with a digenetic life cycle, cause a spectrum of diseases in humans. Recently several Leishmania spp. have been sequenced which significantly boosted the number and quality of proteomic studies conducted. Here a historic review will summarize work of the pre-genomic era and then focus on studies after genome information became available. Firstly works comparing the different life cycle stages, in order to identify stage specific proteins, will be discussed. Identifying post-translational modifications by proteomics especially phosphorylation events will be discussed. Further the contribution of proteomics to the understanding of the molecular mechanism of drug resistance and the investigation of immunogenic proteins for the identification of vaccine candidates will be summarized. Approaches of how potentially secreted proteins were identified are discussed. So far 30-35% of the total predicted proteome of Leishmania spp. have been identified. This comprises mainly the abundant proteins, therefore the last section will look into technological approaches on how this coverage may be increased and what the gel-free and gel-based proteomics have to offer will be compared. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Disrupting mycorrhizal mutualisms: a potential mechanism by which exotic tamarisk outcompetes native cottonwoods.

    Science.gov (United States)

    Meinhardt, Kelley A; Gehring, Catherine A

    2012-03-01

    The disruption of mutualisms between plants and mycorrhizal fungi is a potentially powerful mechanism by which invasives can negatively impact native species, yet our understanding of this mechanism's role in exotic species invasion is still in its infancy. Here, we provide several lines of evidence indicating that invasive tamarisk (Tamarix sp.) negatively affects native cottonwoods (Populus fremontii) by disrupting their associations with arbuscular mycorrhizal (AM) and ectomycorrhizal (EM) fungi. At a field site in the early stages of tamarisk invasion, cottonwoods with tamarisk neighbors had reduced EM colonization and altered EM fungal community composition relative to cottonwoods with native neighbors, leading to reductions in EM propagule abundance in the soil beneath tamarisk. Similarly, AM colonization of cottonwoods was reduced with a tamarisk neighbor, but there were no significant changes in AM fungal spore communities or propagule abundance. Root colonization by nonmycorrhizal fungi, including potential pathogens, was higher in cottonwoods with tamarisk neighbors. A greenhouse experiment in which AM and EM inoculation and plant neighbor were manipulated in a fully factorial design showed that cottonwoods benefited from mycorrhizas, especially EM, in terms of shoot biomass when grown with a conspecific, but shoot biomass was similar to that of nonmycorrhizal controls when cottonwoods were grown with a tamarisk neighbor. These results are partially explained by a reduction in EM but not AM colonization of cottonwoods by a tamarisk neighbor. Tamarisk neighbors negatively affected cottonwood specific leaf area, but not chlorophyll content, in the field. To pinpoint a mechanism for these changes, we measured soil chemistry in the field and the growth response of an EM fungus (Hebeloma crustuliniforme) to salt-amended media in the laboratory. Tamarisk increased both NO3- concentrations and electrical conductivity 2.5-fold beneath neighboring cottonwoods in

  9. Potential Mechanisms for Cancer Resistance in Elephants and Comparative Cellular Response to DNA Damage in Humans.

    Science.gov (United States)

    Abegglen, Lisa M; Caulin, Aleah F; Chan, Ashley; Lee, Kristy; Robinson, Rosann; Campbell, Michael S; Kiso, Wendy K; Schmitt, Dennis L; Waddell, Peter J; Bhaskara, Srividya; Jensen, Shane T; Maley, Carlo C; Schiffman, Joshua D

    2015-11-03

    at higher rates than human lymphocytes proportional to TP53 status (ionizing radiation exposure: patients with LFS, 2.71% [95% CI, 1.93%-3.48%] vs human controls, 7.17% [95% CI, 5.91%-8.44%] vs elephants, 14.64% [95% CI, 10.91%-18.37%]; P elephants, 24.77% [95% CI, 23.0%-26.53%]; P elephants appeared to have a lower-than-expected rate of cancer, potentially related to multiple copies of TP53. Compared with human cells, elephant cells demonstrated increased apoptotic response following DNA damage. These findings, if replicated, could represent an evolutionary-based approach for understanding mechanisms related to cancer suppression.

  10. Imaging Action Potential in Single Mammalian Neurons by Tracking the Accompanying Sub-Nanometer Mechanical Motion.

    Science.gov (United States)

    Yang, Yunze; Liu, Xian-Wei; Wang, Hui; Yu, Hui; Guan, Yan; Wang, Shaopeng; Tao, Nongjian

    2018-03-28

    Action potentials in neurons have been studied traditionally by intracellular electrophysiological recordings and more recently by the fluorescence detection methods. Here we describe a label-free optical imaging method that can measure mechanical motion in single cells with a sub-nanometer detection limit. Using the method, we have observed sub-nanometer mechanical motion accompanying the action potential in single mammalian neurons by averaging the repeated action potential spikes. The shape and width of the transient displacement are similar to those of the electrically recorded action potential, but the amplitude varies from neuron to neuron, and from one region of a neuron to another, ranging from 0.2-0.4 nm. The work indicates that action potentials may be studied noninvasively in single mammalian neurons by label-free imaging of the accompanying sub-nanometer mechanical motion.

  11. Estimating the size of the potential market for the Kyoto flexibility mechanisms

    NARCIS (Netherlands)

    Zhang, Zhong Xiang

    1999-01-01

    The Kyoto Protocol incorporates emissions trading, joint implementation and the clean development mechanism to help Annex I countries to meet their Kyoto targets at a lower overall cost. This paper aims to estimate the size of the potential market for all three flexibility mechanisms under the Kyoto

  12. Potential mechanisms linking probiotics to diabetes: a narrative review of the literature

    OpenAIRE

    Miraghajani, Maryam; Dehsoukhteh, Somayeh Shahraki; Rafie, Nahid; Hamedani, Sahar Golpour; Sabihi, Sima; Ghiasvand, Reza

    2017-01-01

    ABSTRACT CONTEXT AND OBJECTIVE: Some studies have suggested a wide range of possible mechanisms through which probiotics may play a role in diabetes prevention and treatment. However, the underlying mechanisms are not fully understood. We conducted this study to review the potential mechanisms suggested for the effect of probiotics in diabetes. DESIGN AND SETTING: Narrative review conducted at the Food Security Research Center of Isfahan. METHODS: A search in the electronic databases ME...

  13. Towards a neurobiological understanding of pain in chronic pancreatitis: mechanisms and implications for treatment

    Directory of Open Access Journals (Sweden)

    Søren S. Olesen

    2017-12-01

    Conclusion:. Chronic pancreatitis is associated with abnormal processing of pain at the peripheral and central level of the pain system. This neurobiological understanding of pain has important clinical implications for treatment and prevention of pain chronification.

  14. Analysis of the Educational Potential of a Science Museum Learning Environment: Visitors' Experience with and Understanding of an Immersion Exhibit

    Science.gov (United States)

    Mortensen, Marianne Foss

    2011-01-01

    Research pertaining to science museum exhibit design tends to be articulated at a level of generality that makes it difficult to apply in practice. To address this issue, the present study used a design-based research approach to understand the educational potential of a biology exhibit. The exhibit was considered an educational environment which…

  15. Toward Understanding the Potential of Games for Learning: Learning Theory, Game Design Characteristics, and Situating Video Games in Classrooms

    Science.gov (United States)

    Turkay, Selen; Hoffman, Daniel; Kinzer, Charles K.; Chantes, Pantiphar; Vicari, Christopher

    2014-01-01

    Researchers have argued that an effort should be made to raise teachers' and parents' awareness of the potentially positive educational benefits of playing video games (e.g., see Baek, 2008). One part of this effort should be to increase understanding of how video games can be situated within teachers' existing goals and knowledge…

  16. Soft systems methodology as a potential approach to understanding non-motorised transport users in South Africa

    CSIR Research Space (South Africa)

    Van Rooyen, CE

    2016-07-01

    Full Text Available of this paper is to show the potential of using systems thinking and more particularly Soft Systems Methodology (SSM) as a practical and beneficial instrument that will guide BEPDPs with the ongoing learning process of understanding NMT users and their specific...

  17. Advances in understanding of soil biogeochemical cycles: the mechanism of HS entry into the root interior

    Science.gov (United States)

    Aleksandrova, Olga

    2017-04-01

    Humic substances represent the major reservoir of carbon (C) in ecosystems, and their turnover is crucial for understanding the global C cycle. As shown by some investigators [1-2], the phenomenon of the uptake of the whole humic particles by plant roots is a significant step of biogeochemical cycle of carbon in soils. The mechanism of HS entry the root interior remained unknown for a long time. However recently, the last one was discovered [3]. An advanced model [3] includes two hypotheses. These hypotheses are as follows: (1) each nano-size particle possesses a quantum image that can be revealed as a packet of electromagnetic waves; (2) the interaction of nano-size particle with the membrane (plasma membrane) of living cells, on which it is adsorbed, occurs via the development of the Rayleigh-Taylor (RT) instability on the membrane surface. An advanced model allows us to look insight some into some phenomena that were observed by experiments but remained not understood [2]. The authors [2] applied tritium autoradiography to wheat seedlings cultivated with tritium-labeled HS to consider the uptake of humic particles by plant roots. They found a significant increase in the content of some polar (monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulfoquinovosyl diacylglycerol (SQDG) and phosphatidylcholine (PC)) and neutral (free fatty acids, FFA) lipids which were detected in the wheat seedlings treated with humic particles. Authors [2] pointed that lipids MGDG, DGDG, SQDG are crucial for functional and structural integrity of the photosystem complex. Therefore, a stimulating action of adsorbed humic particles evoked phenomena like photosynthesis in root cells that can be interpreted using an advanced model: humic particles being nano-size particles become adsorbed on the plant roots in soils, and influence their micro environment, where they are located, with the specific electromagnetic exposure. Another finding of authors consisted in the

  18. Understanding the Mechanism of the Hydrogen Abstraction from Arachidonic Acid Catalyzed by the Human Enzyme 15-Lipoxygenase-2. A Quantum Mechanics/Molecular Mechanics Free Energy Simulation.

    Science.gov (United States)

    Suardíaz, Reynier; Jambrina, Pablo G; Masgrau, Laura; González-Lafont, Àngels; Rosta, Edina; Lluch, José M

    2016-04-12

    Lipoxygenases (LOXs) are a family of enzymes involved in the biosynthesis of several lipid mediators. In the case of human 15-LOX, the 15-LOX-1 and 15-LOX-2 isoforms show slightly different reaction regiospecificity and substrate specificity, indicating that substrate binding and recognition may be different, a fact that could be related to their different biological role. Here, we have used long molecular dynamics simulations, QM(DFT)/MM potential energy and free energy calculations (using the newly developed DHAM method), to investigate the binding mode of the arachidonic acid (AA) substrate into 15-LOX-2 and the rate-limiting hydrogen-abstraction reaction 15-LOX-2 catalyzes. Our results strongly indicate that hydrogen abstraction from C13 in 15-LOX-2 is only consistent with the "tail-first" orientation of AA, with its carboxylate group interacting with Arg429, and that only the pro-S H13 hydrogen will be abstracted (being the pro-R H13 and H10 too far from the acceptor oxygen atom). At the B3LYP/6-31G(d) level the potential and free energy barriers for the pro-S H13 abstraction of AA by 15-LOX-2 are 18.0 and 18.6 kcal/mol, respectively. To analyze the kinetics of the hydrogen abstraction process, we determined a Markov model corresponding to the unbiased simulations along the state-discretized reaction coordinate. The calculated rates based on the second largest eigenvalue of the Markov matrices agree well with experimental measurements, and also provide the means to directly determine the pre-exponential factor for the reaction by comparing with the free energy barrier height. Our calculated pre-exponential factor is close to the value of kBT/h. On the other hand, our results suggest that the spin inversion of the complete system (including the O2 molecule) that is required to happen at some point along the full process to lead to the final hydroperoxide product, is likely to take place during the hydrogen transfer, which is a proton coupled electron transfer

  19. Nuclear Magnetic Shielding Constants from Quantum Mechanical/Molecular Mechanical Calculations Using Polarizable Embedding: Role of the Embedding Potential

    DEFF Research Database (Denmark)

    Steinmann, Casper; Olsen, Jógvan Magnus Haugaard; Kongsted, Jacob

    2014-01-01

    We present NMR shielding constants obtained through quantum mechanical/molecular mechanical (QM/MM) embedding calculations. Contrary to previous reports, we show that a relatively small QM region is sufficient, provided that a high-quality embedding potential is used. The calculated averaged NMR...... shielding constants of both acrolein and acetone solvated in water are based on a number of snapshots extracted from classical molecular dynamics simulations. We focus on the carbonyl chromophore in both molecules, which shows large solvation effects, and we study the convergence of shielding constants...

  20. Genetic programs of the developing tuberal hypothalamus and potential mechanisms of their disruption by environmental factors.

    Science.gov (United States)

    Nesan, Dinushan; Kurrasch, Deborah M

    2016-12-15

    The hypothalamus is a critical regulator of body homeostasis, influencing the autonomic nervous system and releasing trophic hormones to modulate the endocrine system. The developmental mechanisms that govern formation of the mature hypothalamus are becoming increasingly understood as research in this area grows, leading us to gain appreciation for how these developmental programs are susceptible to disruption by maternal exposure to endocrine disrupting chemicals or other environmental factors in utero. These vulnerabilities, combined with the prominent roles of the various hypothalamic nuclei in regulating appetite, reproductive behaviour, mood, and other physiologies, create a window whereby early developmental disruption can have potent long-term effects. Here we broadly outline our current understanding of hypothalamic development, with a particular focus on the tuberal hypothalamus, including what is know about nuclear coalescing and maturation. We finish by discussing how exposure to environmental or maternally-derived factors can perhaps disrupt these hypothalamic developmental programs, and potentially lead to neuroendocrine disease states. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  1. Potential Mechanisms for Racial and Ethnic Differences in Antimüllerian Hormone and Ovarian Reserve

    Directory of Open Access Journals (Sweden)

    Reshef Tal

    2013-01-01

    Full Text Available Accumulating evidence suggests that reproductive potential and function may be different across racial and ethnic groups. Racial differences have been demonstrated in pubertal timing, infertility, outcomes after assisted reproductive technology (ART treatment, and reproductive aging. Recently, racial differences have also been described in serum antimüllerian hormone (AMH, a sensitive biomarker of ovarian reserve, supporting the notion that ovarian reserve differs between racial/ethnic groups. The existence of such racial/ethnic differences in ovarian reserve, as reflected by AMH, may have important clinical implications for reproductive endocrinologists. However, the mechanisms which may underlie such racial differences in ovarian reserve are unclear. Various genetic factors and environmental factors such as obesity, smoking, and vitamin D deficiency which have been shown to correlate with serum AMH levels and also display significant racial/ethnic variations are discussed in this review. Improving our understanding of racial differences in ovarian reserve and their underlying causes may be essential for infertility treatment in minority women and lead to better reproductive planning, improved treatment outcomes, and timely interventions which may prolong reproductive lifespan in these women.

  2. Thymidylate limitation potentiates cephalosporin activity towards enterococci via an exopolysaccharide-based mechanism

    Science.gov (United States)

    Hoff, Jessica S.; Kristich, Christopher J.

    2016-01-01

    Multi-drug resistant enterococci are major causes of nosocomial infections. Prior therapy with cephalosporins increases the risk of developing an enterococcal infection due to the intrinsic resistance of enterococci to these antibiotics. While progress has been made towards understanding the genetic and biochemical mechanisms of cephalosporin resistance, available data indicate that as-yet-unidentified resistance factors must exist. Here we describe results of a screen to identify small molecules capable of sensitizing enterococci to broad-spectrum cephalosporins. We found that both Enterococcus faecalis and Enterococcus faecium were sensitized to broad and expanded-spectrum cephalosporins when thymidylate production was impaired, whether by direct inhibition of thymidylate synthase, or by limiting production of cofactors required for its activity. Cephalosporin potentiation is the result of altered exopolysaccharide production due to reduced dTDP-glucose synthesis. Hence, exopolysaccharide production is a previously undescribed contributor to the intrinsic cephalosporin resistance of enterococci and serves as new target for anti-enterococcal therapeutics. PMID:27008338

  3. [Effects of biochar on soil nutrients leaching and potential mechanisms: A review].

    Science.gov (United States)

    Liu, Yu-xue; Lyu, Hao-hao; Shi, Yan; Wang, Yao-feng; Zhong, Zhe-ke; Yang, Sheng-mao

    2015-01-01

    Controlling soil nutrient leaching in farmland ecosystems has been a hotspot in the research field of agricultural environment. Biochar has its unique physical and chemical properties, playing a significant role in enhancing soil carbon storage, improving soil quality and increasing crop yield. As a kind of new exogenous material, biochar has the potential in impacting soil nutrient cycling directly or indirectly, and has profound influences on soil nutrient leaching. This paper analyzed the intrinsic factors affecting how biochar affects soil nutrient leaching, such as the physical and chemical properties of biochar, and the interaction between biochar and soil organisms. Then the latest literatures regarding the external factors, including biochar application rates, soil types, depth of soil layer, fertilization conditions and temporal dynamics, through which biochar influences soil nutrient (especially nitrogen and phosphorus) leaching were reviewed. On that basis, four related action mechanisms were clarified, including direct adsorption of nutrients by biochar due to its micropore structure or surface charge, influencing nutrient leaching through increasing soil water- holding capacity, influencing nutrient cycling through the interaction with soil microbes, and preferential transport of absorbed nutrients by fine biochar particles. At last future research directions for better understanding the interactions between biochar and nutrient leaching in the soil were proposed.

  4. Gastrointestinal obstruction caused by solidification and coagulation of enteral nutrition: pathogenetic mechanisms and potential risk factors

    Directory of Open Access Journals (Sweden)

    Leonello G

    2018-04-01

    Full Text Available Grazia Leonello,1 Antonio Giacomo Rizzo,1 Viviane Di Dio,2 Antonio Soriano,3 Claudia Previti,3 Grazia Giulia Pantè,3 Claudio Mastrojeni,1 Sebastiano Pantè1 1Department of Human Pathology of Adults and Evolutive Era “Gaetano Barresi”, University of Messina, Messina, Italy; 2Health Research Institute Bonino Pulejo, Piemonte Hospital, Messina, Italy; 3Department of Medical and Surgery Science, University of Messina, Messina, Italy Abstract: Enteral nutrition (EN is preferred in order to provide nutrition and reduce catabolism in critically ill patients. Recent studies suggest that the use of EN is successful and complications are rare. However, an underestimated mechanical complication of tube feedings seen in critically ill patients is the coagulation and solidification of the EN causing gastrointestinal obstruction. This report describes two clinical cases (1.23% of all cases seen at our clinic of obstruction and perforation of the small bowel secondary to the solidification of EN. The understanding and early recognition of this potential complication are essential for the prevention and successful treatment of this condition. Keywords: enteral nutrition, gastrointestinal contents, intestinal obstruction, small-bowel bezoar

  5. Associations of Musculoskeletal Pain With Mobility in Older Adults: Potential Cerebral Mechanisms.

    Science.gov (United States)

    Cruz-Almeida, Yenisel; Rosso, Andrea; Marcum, Zachary; Harris, Tamara; Newman, Anne B; Nevitt, Michael; Satterfield, Suzanne; Yaffe, Kristine; Rosano, Caterina

    2017-09-01

    Musculoskeletal pain is highly prevalent and limits mobility in older adults. A potential mechanism by which pain affects mobility could be through its negative impact on the brain. We examined whether structural integrity of cerebral gray and white matter (WM) mediated the relationship between pain and mobility in community-dwelling older adults. Musculoskeletal pain, gait speed, and neuroimaging data were obtained concurrently from the Health ABC study (mean age = 83/56% female, n = 212). Microstructural gray matter integrity was measured by mean diffusivity (MD), WM microstructure and macrostructure were measured by fractional anisotropy (FA) and WM hyperintensities (WMH), respectively. Regression models were adjusted for gray matter atrophy, age, gender, medication use, and obesity. Bootstrapped mediation methods were used (1,000 bootstrapped samples, 95% confidence intervals). The associations of musculoskeletal pain with WMH (β = .19, p mobility, although pre-existing WM integrity may also simultaneously amplify pain and decrease mobility. Future studies are needed to further understand whether successful pain management may significantly improve both brain health and mobility. © The Author 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  6. The Double-Well Potential in Quantum Mechanics: A Simple, Numerically Exact Formulation

    Science.gov (United States)

    Jelic, V.; Marsiglio, F.

    2012-01-01

    The double-well potential is arguably one of the most important potentials in quantum mechanics, because the solution contains the notion of a state as a linear superposition of "classical" states, a concept which has become very important in quantum information theory. It is therefore desirable to have solutions to simple double-well potentials…

  7. Oxide nanoparticle EUV resists: toward understanding the mechanism of positive and negative tone patterning

    KAUST Repository

    Chakrabarty, Souvik

    2013-04-01

    DUV, EUV and e-beam patterning of hybrid nanoparticle photoresists have been reported previously by Ober and coworkers. The present work explores the underlying mechanism that is responsible for the dual tone patterning capability of these photoresist materials. Spectroscopic results correlated with mass loss and dissolution studies suggest a ligand exchange mechanism responsible for altering the solubility between the exposed and unexposed regions. © 2013 SPIE.

  8. Understanding How Consumer Risks in Digital Social Payments Can Erode Their Financial Inclusion Potential

    OpenAIRE

    Zimmerman, Jamie M.; Baur, Silvia

    2016-01-01

    Digital Social Payments (DSPs) offer a variety of potential benefits over traditional cash, voucher, or in-kind methods. Proponents most often cite increased efficiency, reduced leakage, and faster, more convenient and more secure payments to recipients. When linked to bank accounts or mobile wallets that offer store-of-value opportunities or access to additional financial services, DSPs t...

  9. Using realist synthesis to understand the mechanisms of interprofessional teamwork in health and social care.

    Science.gov (United States)

    Hewitt, Gillian; Sims, Sarah; Harris, Ruth

    2014-11-01

    Realist synthesis offers a novel and innovative way to interrogate the large literature on interprofessional teamwork in health and social care teams. This article introduces realist synthesis and its approach to identifying and testing the underpinning processes (or "mechanisms") that make an intervention work, the contexts that trigger those mechanisms and their subsequent outcomes. A realist synthesis of the evidence on interprofessional teamwork is described. Thirteen mechanisms were identified in the synthesis and findings for one mechanism, called "Support and value" are presented in this paper. The evidence for the other twelve mechanisms ("collaboration and coordination", "pooling of resources", "individual learning", "role blurring", "efficient, open and equitable communication", "tactical communication", "shared responsibility and influence", "team behavioural norms", "shared responsibility and influence", "critically reviewing performance and decisions", "generating and implementing new ideas" and "leadership") are reported in a further three papers in this series. The "support and value" mechanism referred to the ways in which team members supported one another, respected other's skills and abilities and valued each other's contributions. "Support and value" was present in some, but far from all, teams and a number of contexts that explained this variation were identified. The article concludes with a discussion of the challenges and benefits of undertaking this realist synthesis.

  10. Evaluation of potential sources and transport mechanisms of fecal indicator bacteria to beach water, Murphy Park Beach, Door County, Wisconsin

    Science.gov (United States)

    Juckem, Paul F.; Corsi, Steven R.; McDermott, Colleen; Kleinheinz, Gregory; Fogarty, Lisa R.; Haack, Sheridan K.; Johnson, Heather E.

    2013-01-01

    Fecal Indicator Bacteria (FIB) concentrations in beach water have been used for many years as a criterion for closing beaches due to potential health concerns. Yet, current understanding of sources and transport mechanisms that drive FIB occurrence remains insufficient for accurate prediction of closures at many beaches. Murphy Park Beach, a relatively pristine beach on Green Bay in Door County, Wis., was selected for a study to evaluate FIB sources and transport mechanisms. Although the relatively pristine nature of the beach yielded no detection of pathogenic bacterial genes and relatively low FIB concentrations during the study period compared with other Great Lakes Beaches, its selection limited the number of confounding FIB sources and associated transport mechanisms. The primary sources of FIB appear to be internal to the beach rather than external sources such as rivers, storm sewer outfalls, and industrial discharges. Three potential FIB sources were identified: sand, swash-zone groundwater, and Cladophora mats. Modest correlations between FIB concentrations in these potential source reservoirs and FIB concentrations at the beach from the same day illustrate the importance of understanding transport mechanisms between FIB sources and the water column. One likely mechanism for transport and dispersion of FIB from sand and Cladophora sources appears to be agitation of Cladophora mats and erosion of beach sand due to storm activity, as inferred from storm indicators including turbidity, wave height, current speed, wind speed, sky visibility, 24-hour precipitation, and suspended particulate concentration. FIB concentrations in beach water had a statistically significant relation (p-value ‹0.05) with the magnitude of these storm indicators. In addition, transport of FIB in swash-zone groundwater into beach water appears to be driven by groundwater recharge associated with multiday precipitation and corresponding increased swash-zone groundwater discharge at

  11. Understanding the potential risk to marine mammals from collision with tidal turbines

    Energy Technology Data Exchange (ETDEWEB)

    Copping, Andrea; Grear, Molly; Jepsen, Richard; Chartrand, Chris; Gorton, Alicia

    2017-09-01

    The advent of the marine renewable energy industry has raised questions, particularly for tidal turbines, about potential threats to populations of marine mammals. This research examines the sequence of behavioral events that lead up to a potential collision of a marine mammal with a tidal turbine, within the context of the physical environment, the attributes of the tidal device, and the biomechanical properties of a marine mammal that may resist injury from a tidal blade collision. There are currently no data available to determine the risk of collision to a marine mammal, and obtaining those data would be extremely difficult. The surrogate data examined in this research (likelihood of a marine mammal being in close proximity to a tidal turbine, biomechanics of marine mammal tissues, and engineering models) provide insight into the interaction.

  12. Arctic potential : could more structured view improve the understanding of arctic business opportunities?

    OpenAIRE

    Hintsala, Henna; Niemelä, Sami; Tervonen, Pekka

    2016-01-01

    The increasing interest towards the Arctic has been witnessed during the past decades. However, the commonly shared definitions of the Arctic key concepts have not yet penetrated national and international arenas for political and economic decision making. The lack of jointly defined framework has made different analyses related to the Arctic quite limited considering the magnitude of economic potential embedded in Arctic. This paper is built on the key findings of two separate, yet connected...

  13. Monitoring tobacco brand websites to understand marketing strategies aimed at tobacco product users and potential users.

    OpenAIRE

    Escobedo, P; Cruz, TB; Tsai, K-Y; Allem, J-P; Soto, DW; Kirkpatrick, MG; Pattarroyo, M; Unger, JB

    2017-01-01

    Limited information exists about strategies and methods used on brand marketing websites to transmit pro-tobacco messages to tobacco users and potential users. This study compared age verification methods, themes, interactive activities and links to social media across tobacco brand websites.This study examined 12 tobacco brand websites representing four tobacco product categories: cigarettes, cigar/cigarillos, smokeless tobacco, and e-cigarettes. Website content was analyzed by tobacco produ...

  14. Understanding User Preferences and Awareness: Privacy Mechanisms in Location-Based Services

    Science.gov (United States)

    Burghardt, Thorben; Buchmann, Erik; Müller, Jens; Böhm, Klemens

    Location based services (LBS) let people retrieve and share information related to their current position. Examples are Google Latitude or Panoramio. Since LBS share user-related content, location information etc., they put user privacy at risk. Literature has proposed various privacy mechanisms for LBS. However, it is unclear which mechanisms humans really find useful, and how they make use of them. We present a user study that addresses these issues. To obtain realistic results, we have implemented a geotagging application on the web and on GPS cellphones, and our study participants use this application in their daily lives. We test five privacy mechanisms that differ in the awareness, mental effort and degree of informedness required from the users. Among other findings, we have observed that in situations where a single simple mechanism does not meet all privacy needs, people want to use simple and sophisticated mechanisms in combination. Further, individuals are concerned about the privacy of others, even when they do not value privacy for themselves.

  15. Combating mutations in genetic disease and drug resistance: understanding molecular mechanisms to guide drug design.

    Science.gov (United States)

    Albanaz, Amanda T S; Rodrigues, Carlos H M; Pires, Douglas E V; Ascher, David B

    2017-06-01

    Mutations introduce diversity into genomes, leading to selective changes and driving evolution. These changes have contributed to the emergence of many of the current major health concerns of the 21st century, from the development of genetic diseases and cancers to the rise and spread of drug resistance. The experimental systematic testing of all mutations in a system of interest is impractical and not cost-effective, which has created interest in the development of computational tools to understand the molecular consequences of mutations to aid and guide rational experimentation. Areas covered: Here, the authors discuss the recent development of computational methods to understand the effects of coding mutations to protein function and interactions, particularly in the context of the 3D structure of the protein. Expert opinion: While significant progress has been made in terms of innovative tools to understand and quantify the different range of effects in which a mutation or a set of mutations can give rise to a phenotype, a great gap still exists when integrating these predictions and drawing causality conclusions linking variants. This often requires a detailed understanding of the system being perturbed. However, as part of the drug development process it can be used preemptively in a similar fashion to pharmacokinetics predictions, to guide development of therapeutics to help guide the design and analysis of clinical trials, patient treatment and public health policy strategies.

  16. Laboratory Activities to Support Student Understanding of the Molecular Mechanisms of Mutation & Natural Selection

    Science.gov (United States)

    Hubler, Tina; Adams, Patti; Scammell, Jonathan

    2015-01-01

    The molecular basis of evolution is an important and challenging concept for students to understand. In a previous article, we provided some of the scientific background necessary to teach this topic. This article features a series of laboratory activities demonstrating that molecular events can alter the genomes of organisms. These activities are…

  17. Towards an understanding of hot carrier cooling mechanisms in multiple quantum wells

    Science.gov (United States)

    Conibeer, Gavin; Zhang, Yi; Bremner, Stephen P.; Shrestha, Santosh

    2017-09-01

    Multiple quantum wells have been shown significantly reduced hot carrier cooling rates compared to bulk material and are thus a promising candidate for hot carrier solar cell absorbers. However, the mechanism(s) by which hot carrier cooling is restricted is not clear. A systematic study of carrier cooling rates in GaAs/AlAs multiple quantum wells (MQWs) with either varying barrier thickness or varying well thickness is presented in this paper. These allow an investigation as to whether the mechanisms of either a modification in hot carrier diffusion or a localisation of phonons emitted by hot carriers are primarily responsible for reduced carrier cooling rates. With the conclusion that for the structures investigated the situation is rather more complex with both carrier mobility to modify hot carrier diffusion, different diffusion rates for electrons and holes and reflection and localisation of phonons to enhance phonon bottleneck all playing their parts in modulating phonon reabsorption and hot carrier behaviour.

  18. The contribution of experimental in vivo models to understanding the mechanisms of adaptation to mechanical loading in bone

    Directory of Open Access Journals (Sweden)

    Lee B Meakin

    2014-10-01

    Full Text Available Changing loading regimens by natural means such as exercise, with or without interference such as osteotomy, has provided useful information on the structure:function relationship in bone tissue. However, the greatest precision in defining those aspects of the overall strain environment that influence modeling and remodeling behavior has been achieved by relating quantified changes in bone architecture to quantified changes in bones’ strain environment produced by direct, controlled artificial bone loading.Jiri Heřt introduced the technique of artificial loading of bones in vivo with external devices in the 1960s using an electromechanical device to load rabbit tibiae through transfixing stainless steel pins. Quantifying natural bone strains during locomotion by attaching electrical resistance strain gauges to bone surfaces was introduced by Lanyon, also in the 1960s. These studies in a variety of bones in a number of species demonstrated remarkable uniformity in the peak strains and maximum strain rates experienced.Experiments combining strain gauge instrumentation with artificial loading in sheep, pigs, roosters, turkeys, rats and mice has yielded significant insight into the control of strain-related adaptive (remodeling. This diversity of approach has been largely superseded by non-invasive transcutaneous loading in rats and mice which is now the model of choice for many studies. Together such studies have demonstrated that; over the physiological strain range, bone’s mechanically-adaptive processes are responsive to dynamic but not static strains; the size and nature of the adaptive response controlling bone mass is linearly related to the peak loads encountered; the strain-related response is preferentially sensitive to high strain rates and unresponsive to static ones; is most responsive to unusual strain distributions; is maximized by remarkably few strain cycles and that these are most effective when interrupted by short periods of

  19. The Contribution of Experimental in vivo Models to Understanding the Mechanisms of Adaptation to Mechanical Loading in Bone

    Science.gov (United States)

    Meakin, Lee B.; Price, Joanna S.; Lanyon, Lance E.

    2014-01-01

    Changing loading regimens by natural means such as exercise, with or without interference such as osteotomy, has provided useful information on the structure:function relationship in bone tissue. However, the greatest precision in defining those aspects of the overall strain environment that influence modeling and remodeling behavior has been achieved by relating quantified changes in bone architecture to quantified changes in bones’ strain environment produced by direct, controlled artificial bone loading. Jiri Hert introduced the technique of artificial loading of bones in vivo with external devices in the 1960s using an electromechanical device to load rabbit tibiae through transfixing stainless steel pins. Quantifying natural bone strains during locomotion by attaching electrical resistance strain gages to bone surfaces was introduced by Lanyon, also in the 1960s. These studies in a variety of bones in a number of species demonstrated remarkable uniformity in the peak strains and maximum strain rates experienced. Experiments combining strain gage instrumentation with artificial loading in sheep, pigs, roosters, turkeys, rats, and mice has yielded significant insight into the control of strain-related adaptive (re)modeling. This diversity of approach has been largely superseded by non-invasive transcutaneous loading in rats and mice, which is now the model of choice for many studies. Together such studies have demonstrated that over the physiological strain range, bone’s mechanically adaptive processes are responsive to dynamic but not static strains; the size and nature of the adaptive response controlling bone mass is linearly related to the peak loads encountered; the strain-related response is preferentially sensitive to high strain rates and unresponsive to static ones; is most responsive to unusual strain distributions; is maximized by remarkably few strain cycles, and that these are most effective when interrupted by short periods of rest between them

  20. Multiscale Mechanics of Articular Cartilage: Potentials and Challenges of Coupling Musculoskeletal, Joint, and Microscale Computational Models

    Science.gov (United States)

    Halloran, J. P.; Sibole, S.; van Donkelaar, C. C.; van Turnhout, M. C.; Oomens, C. W. J.; Weiss, J. A.; Guilak, F.; Erdemir, A.

    2012-01-01

    Articular cartilage experiences significant mechanical loads during daily activities. Healthy cartilage provides the capacity for load bearing and regulates the mechanobiological processes for tissue development, maintenance, and repair. Experimental studies at multiple scales have provided a fundamental understanding of macroscopic mechanical function, evaluation of the micromechanical environment of chondrocytes, and the foundations for mechanobiological response. In addition, computational models of cartilage have offered a concise description of experimental data at many spatial levels under healthy and diseased conditions, and have served to generate hypotheses for the mechanical and biological function. Further, modeling and simulation provides a platform for predictive risk assessment, management of dysfunction, as well as a means to relate multiple spatial scales. Simulation-based investigation of cartilage comes with many challenges including both the computational burden and often insufficient availability of data for model development and validation. This review outlines recent modeling and simulation approaches to understand cartilage function from a mechanical systems perspective, and illustrates pathways to associate mechanics with biological function. Computational representations at single scales are provided from the body down to the microstructure, along with attempts to explore multiscale mechanisms of load sharing that dictate the mechanical environment of the cartilage and chondrocytes. PMID:22648577

  1. Understanding the mechanism of nanotube synthesis for controlled production of specific (n,m) structures

    Energy Technology Data Exchange (ETDEWEB)

    Resasco, Daniel E.

    2010-02-11

    This report shows the extensive research on the mechanism responsible for the formation of single walled carbon nanotubes in order to get control over their structural parameters (diameter and chirality). Catalyst formulations, pre-treatment conditions, and reaction conditions are described in detail as well as mechanisms to produce nanotubes structures of specific arrays (vertical forest, nanotube pillars). Applications of SWNT in different fields are also described in this report. In relation to this project five students have graduated (3 PhD and 2 MS) and 35 papers have been published.

  2. A mathematical model towards understanding the mechanism of neuronal regulation of wake-NREMS-REMS states.

    Directory of Open Access Journals (Sweden)

    Rupesh Kumar

    Full Text Available In this study we have constructed a mathematical model of a recently proposed functional model known to be responsible for inducing waking, NREMS and REMS. Simulation studies using this model reproduced sleep-wake patterns as reported in normal animals. The model helps to explain neural mechanism(s that underlie the transitions between wake, NREMS and REMS as well as how both the homeostatic sleep-drive and the circadian rhythm shape the duration of each of these episodes. In particular, this mathematical model demonstrates and confirms that an underlying mechanism for REMS generation is pre-synaptic inhibition from substantia nigra onto the REM-off terminals that project on REM-on neurons, as has been recently proposed. The importance of orexinergic neurons in stabilizing the wake-sleep cycle is demonstrated by showing how even small changes in inputs to or from those neurons can have a large impact on the ensuing dynamics. The results from this model allow us to make predictions of the neural mechanisms of regulation and patho-physiology of REMS.

  3. The Mediated MIMIC Model for Understanding the Underlying Mechanism of DIF

    Science.gov (United States)

    Cheng, Ying; Shao, Can; Lathrop, Quinn N.

    2016-01-01

    Due to its flexibility, the multiple-indicator, multiple-causes (MIMIC) model has become an increasingly popular method for the detection of differential item functioning (DIF). In this article, we propose the mediated MIMIC model method to uncover the underlying mechanism of DIF. This method extends the usual MIMIC model by including one variable…

  4. Understanding the antimicrobial mechanism of TiO2-based nanocomposite films in a pathogenic bacterium

    NARCIS (Netherlands)

    Kubacka, A.; Suarez Diez, M.; Rojo, D.; Bargiela, R.; Ciordia, S.; Zapico, I.; Albar, J.P.; Barbas, C.; Martins Dos Santos, V.A.P.; Fernández-García, M.; Ferrer, M.

    2014-01-01

    Titania (TiO2)-based nanocomposites subjected to light excitation are remarkably effective in eliciting microbial death. However, the mechanism by which these materials induce microbial death and the effects that they have on microbes are poorly understood. Here, we assess the low dose

  5. Understanding the mechanism of action of triazine-phosphonate derivatives as flame retardants for cotton fabrics

    Science.gov (United States)

    Countless hours of research and studies on triazine, phosphonate and their combination have provided insightful information into their flame retardant properties on polymeric systems. However, only limited number of studies shed light on the mechanism of flame retardant cotton fabrics. The purpose...

  6. Improving Student Understanding of Addition of Angular Momentum in Quantum Mechanics

    Science.gov (United States)

    Zhu, Guangtian; Singh, Chandralekha

    2013-01-01

    We describe the difficulties advanced undergraduate and graduate students have with concepts related to addition of angular momentum in quantum mechanics. We also describe the development and implementation of a research-based learning tool, Quantum Interactive Learning Tutorial (QuILT), to reduce these difficulties. The preliminary evaluation…

  7. A Changing Landscape of Advanced Prostate Cancer: Understanding Mechanisms of Resistance to Potent Hormonal Therapies

    Science.gov (United States)

    2016-10-01

    mechanisms of NEPC progression using deep sequencing techniques of metastatic tumor biopsies and non-invasively using liquid biopsies including...from each site. (b) AR signaling (right) based on abundance of mRNA transcripts included in the AR signaling signature described in ref 19. Violin

  8. Recent advances in understanding the reinforcing ability and mechanism of carbon nanotubes in ceramic matrix composites

    International Nuclear Information System (INIS)

    Estili, Mehdi; Sakka, Yoshio

    2014-01-01

    Since the discovery of carbon nanotubes (CNTs), commonly referred to as ultimate reinforcement, the main purpose for fabricating CNT–ceramic matrix composites has been mainly to improve the fracture toughness and strength of the ceramic matrix materials. However, there have been many studies reporting marginal improvements or even the degradation of mechanical properties. On the other hand, those studies claiming noticeable toughening measured using indentation, which is an indirect/unreliable characterization method, have not demonstrated the responsible mechanisms applicable to the nanoscale, flexible CNTs; instead, those studies proposed those classical methods applicable to microscale fiber/whisker reinforced ceramics without showing any convincing evidence of load transfer to the CNTs. Therefore, the ability of CNTs to directly improve the macroscopic mechanical properties of structural ceramics has been strongly questioned and debated in the last ten years. In order to properly discuss the reinforcing ability (and possible mechanisms) of CNTs in a ceramic host material, there are three fundamental questions to our knowledge at both the nanoscale and macroscale levels that need to be addressed: (1) does the intrinsic load-bearing ability of CNTs change when embedded in a ceramic host matrix?; (2) when there is an intimate atomic-level interface without any chemical reaction with the matrix, could one expect any load transfer to the CNTs along with effective load bearing by them during crack propagation?; and (3) considering their nanometer-scale dimensions, flexibility and radial softness, are the CNTs able to improve the mechanical properties of the host ceramic matrix at the macroscale when individually, intimately and uniformly dispersed? If so, how? Also, what is the effect of CNT concentration in such a defect-free composite system? Here, we briefly review the recent studies addressing the above fundamental questions. In particular, we discuss the new

  9. Towards the Biological Understanding of CTC: Capture Technologies, Definitions and Potential to Create Metastasis

    Directory of Open Access Journals (Sweden)

    Ana M.C. Barradas

    2013-12-01

    Full Text Available Circulating Tumor Cells (CTC are rare cells originated from tumors that travel into the blood stream, extravasate to different organs of which only a small fraction will develop into metastasis. The presence of CTC enumerated with the CellSearch system is associated with a relative short survival and their continued presence after the first cycles of therapy indicates a futile therapy in patients with metastatic carcinomas. Detailed characterization of CTC holds the promise to enable the choice of the optimal therapy for the individual patients during the course of the disease. The phenotype, physical and biological properties are however not well understood making it difficult to assess the merit of recent technological advancements to improve upon the capture of CTC or to evaluate their metastatic potential. Here we will discuss the recent advances in the classification of CTC captured by the CellSearch system, the implications of their features and numbers. Latest capture platforms are reviewed and placed in the light of technology improvements needed to detect CTC. Physical properties, phenotype, viability and proliferative potential and means to assess their proliferation and metastatic capacity will be summarized and placed in the context of the latest CTC capture platforms.

  10. Understanding the properties of chitosan aryl substituted thioureas in their role and potential as antibacterial agents

    Science.gov (United States)

    Khairul, Wan M.; Daud, Adibah Izzati; Ismail, Noraznawati

    2018-02-01

    In this study, the effort was to design and synthesize a series of thiourea-chitosan derivatives featuring five aryl substituted members namely N-chitosan-N'-(4-nitrobenzoyl) thiourea (1), N-chitosan-N'-(4-chlorobenzoyl) thiourea (2), N-chitosan-N'-(4-methylbenzoyl) thiourea (3), N-chitosan-N'-(2-iodobenzoyl) thiourea (4), and N-chitosan-N'-(2-methylbenzoyl) thiourea (5) via SN2 reaction pathway having different donating and withdrawing groups. Their molecular structures were then characterised by FT-IR, UV-Vis, and thermogravimetric analysis (TGA). The antimicrobial activities of these derivatives against four species bacteria Bacillus cereus, Staphylococcus aureus, Salmonella typhi, and Escherichia coli of both Gram-positive and Gram-negative type bacteria at minimum concentration 6mg/ml were carried out to investigate their potential as antibacterial agents. Compound 1 exhibited specific activity as it can only inhibit Gram-positive bacteria while other compounds 2-5 showed broad range spectrum activity as they were able to inhibit both Gram-positive and Gram-negative bacteria. Therefore, 1-5 showed good antibacterial activity and have high potential to be further developed as active materials in pharmaceutical interests.

  11. Understanding the Impact of Film Disorder and Local Surface Potential in Ultraviolet Photoelectron Spectroscopy of PEDOT.

    Science.gov (United States)

    Muñoz, William A; Crispin, Xavier; Fahlman, Mats; Zozoulenko, Igor V

    2018-02-01

    The spectra of conducting polymers obtained using ultraviolet photoelectron spectroscopy (UPS) exhibit a typical broadening of the tail σ UPS ≈ 1 eV, which by an order of magnitude exceeds a commonly accepted value of the broadening of the tail of the density of states σ DOS ≈ 0.1 eV obtained using transport measurements. In this work, an origin of this anomalous broadening of the tail of the UPS spectra in a doped conducting polymer, PEDOT (poly(3,4-ethylenedioxythiophene)), is discussed. Based on the semiempirical approach and using a realistic morphological model, the density of valence states in PEDOT doped with molecular counterions is computed. It is shown that due to a disordered character of the material with randomly distributed counterions, the localized charge carriers in PEDOT crystallites experience spatially varying electrostatic potential. This leads to spatially varying local vacuum levels and binding energies. Taking this variation into account the UPS spectrum is obtained with the broadening of the tail comparable to the experimentally observed one. The results imply that the observed broadening of the tail of the UPS spectra in PEDOT provides information about a disordered spatially varying potential in the material rather than the broadening of the DOS itself. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Understanding NOx SCR Mechanism and Activity on Cu/Chabazite Structures throughout the Catalyst Life Cycle

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Fabio; Delgass, Nick; Gounder, Rajmani; Schneider, William F.; Miller, Jeff; Yezerets, Aleksey; McEwen, Jean-Sabin; Peden, Charles HF; Howden, Ken

    2014-12-09

    Oxides of nitrogen (NOx) compounds contribute to acid rain and photochemical smog and have been linked to respiratory ailments. NOx emissions regulations continue to tighten, driving the need for high performance, robust control strategies. The goal of this project is to develop a deep, molecular level understanding of the function of Cu-SSZ-13 and Cu-SAPO-34 materials that catalyze the SCR of NOx with NH3.

  13. Cycle length restitution in sinoatrial node cells: a theory for understanding spontaneous action potential dynamics.

    Directory of Open Access Journals (Sweden)

    Patric Glynn

    Full Text Available Normal heart rhythm (sinus rhythm is governed by the sinoatrial node, a specialized and highly heterogeneous collection of spontaneously active myocytes in the right atrium. Sinoatrial node dysfunction, characterized by slow and/or asynchronous pacemaker activity and even failure, is associated with cardiovascular disease (e.g. heart failure, atrial fibrillation. While tremendous progress has been made in understanding the molecular and ionic basis of automaticity in sinoatrial node cells, the dynamics governing sinoatrial nodel cell synchrony and overall pacemaker function remain unclear. Here, a well-validated computational model of the mouse sinoatrial node cell is used to test the hypothesis that sinoatrial node cell dynamics reflect an inherent restitution property (cycle length restitution that may give rise to a wide range of behavior from regular periodicity to highly complex, irregular activation. Computer simulations are performed to determine the cycle length restitution curve in the computational model using a newly defined voltage pulse protocol. The ability of the restitution curve to predict sinoatrial node cell dynamics (e.g., the emergence of irregular spontaneous activity and susceptibility to termination is evaluated. Finally, ionic and tissue level factors (e.g. ion channel conductances, ion concentrations, cell-to-cell coupling that influence restitution and sinoatrial node cell dynamics are explored. Together, these findings suggest that cycle length restitution may be a useful tool for analyzing cell dynamics and dysfunction in the sinoatrial node.

  14. Radiometric maps of Israel - Partial contribution to the understanding of potential radon emanations

    International Nuclear Information System (INIS)

    Vulkan, U.; Shirav, M.

    1997-01-01

    An airborne radiometric survey over parts of Israel was carried out in 1981. The system was comprised from 10 Nal 4 inch x 4 inch x 16 inch detectors, arranged in 4,4 and 2 sensors, with total volume of 1560 inch 3 , and one 4 inch x 4 inch x 16 inch uplooking Nal detector. Flight nominal height was 400 feet. It was found that the Mount Scopus Group (of Senonian origin) is the main source for high uranium - phosphorite rocks of this group contain up to 150 ppm U. Comparing the eU radiometric map with a map of potential radon emanation from rock units, reveals a fair correlation - high radon emanation usually follow the distribution of the Mount Scopus Group in Israel. The correlation between the two maps is excellent over arid terrain where soil cover is missing, whereas over semi-arid - humid areas (western and northern Israel), where soil and cultivation covers are developed, the eU levels over Mount Scopus Group's outcrops are much lower due to absorption of the radiation, and do not depict the full radon potential. Detailed mapping of radon hazards usually exhibit poor correlation between airborne eU data and direct pore radon measurements, even in arid terrain. This phenomenon is attributed to the fact that a radon ''source rock'' (e.g. phosphorite) could be covered with a few up to some tenths of meters of uranium-barren rock. About 0.5 meter cover is enough to absorb all radiation, causing very low airborne eU readings, while the radon free way in this rock is about 10 meters, yielding high pore radon levels when directly measured

  15. Progress in understanding the mechanical behavior of pressure-vessel materials at elevated temperatures

    International Nuclear Information System (INIS)

    Swindeman, R.W.; Brinkman, C.R.

    1981-01-01

    Progress during the 1970's on the production of high-temperature mechanical properties data for pressure vessel materials was reviewed. The direction of the research was toward satisfying new data requirements to implement advances in high-temperature inelastic design methods. To meet these needs, servo-controlled testing machines and high-resolution extensometry were developed to gain more information on the essential behavioral features of high-temperature alloys. The similarities and differences in the mechanical response of various pressure vessel materials were identified. High-temperature pressure vessel materials that have received the most attention included Type 304 stainless steel, Type 316 stainless steel, 2 1/4 Cr-1 Mo steel, alloy 800H, and Hastelloy X

  16. Understanding the Acute Skin Injury Mechanism Caused by Player-Surface Contact During Soccer

    Science.gov (United States)

    van den Eijnde, Wilbert A.J.; Peppelman, Malou; Lamers, Edwin A.D.; van de Kerkhof, Peter C.M.; van Erp, Piet E.J.

    2014-01-01

    Background: Superficial skin injuries are considered minor, and their incidence is probably underestimated. Insight into the incidence and mechanism of acute skin injury can be helpful in developing suitable preventive measures and safer playing surfaces for soccer and other field sports. Purpose: To gain insight into the incidence and severity of skin injuries related to soccer and to describe the skin injury mechanism due to player-surface contact. Study Design: Systematic review; Level of evidence, 4. Methods: The prevention model by van Mechelen et al (1992) combined with the injury causation model of Bahr and Krosshaug (2005) were used as a framework for the survey to describe the skin injury incidence and mechanism caused by player-surface contact. Results: The reviewed literature showed that common injury reporting methods are mainly based on time lost from participation or the need for medical attention. Because skin abrasions seldom lead to absence or medical attention, they are often not reported. When reported, the incidence of abrasion/laceration injuries varies from 0.8 to 6.1 injuries per 1000 player-hours. Wound assessment techniques such as the Skin Damage Area and Severity Index can be a valuable tool to obtain a more accurate estimation of the incidence and severity of acute skin injuries. Conclusion: The use of protective equipment, a skin lubricant, or wet surface conditions has a positive effect on preventing abrasion-type injuries from artificial turf surfaces. The literature also shows that essential biomechanical information of the sliding event is lacking, such as how energy is transferred to the area of contact. From a clinical and histological perspective, there are strong indications that a sliding-induced skin lesion is caused by mechanical rather than thermal injury to the skin. PMID:26535330

  17. Understanding the Personality and Behavioral Mechanisms Defining Hypersexuality in Men Who Have Sex With Men.

    Science.gov (United States)

    Miner, Michael H; Romine, Rebecca Swinburne; Raymond, Nancy; Janssen, Erick; MacDonald, Angus; Coleman, Eli

    2016-09-01

    Hypersexuality has been conceptualized as sexual addiction, compulsivity, and impulsivity, among others, in the absence of strong empirical data in support of any specific conceptualization. To investigate personality factors and behavioral mechanisms that are relevant to hypersexuality in men who have sex with men. A sample of 242 men who have sex with men was recruited from various sites in a moderate-size mid-western city. Participants were assigned to a hypersexuality group or a control group using an interview similar to the Structured Clinical Interview for the Diagnostic and Statistical Manual for Mental Disorders, Fourth Edition. Self-report inventories were administered that measured the broad personality constructs of positive emotionality, negative emotionality, and constraint and more narrow constructs related to sexual behavioral control, behavioral activation, behavioral inhibition, sexual excitation, sexual inhibition, impulsivity, attention-deficit/hyperactivity disorder, and sexual behavior. Hierarchical logistic regression was used to determine the relation between these personality and behavioral variables and group membership. A hierarchical logistic regression controlling for age showed a significant positive relation between hypersexuality and negative emotionality and a negative relation with constraint. None of the behavioral mechanism variables entered this equation. However, a hierarchical multiple regression analysis predicting sexual behavioral control indicated that lack of such control was positively related to sexual excitation and sexual inhibition owing to the threat of performance failure and negatively related to sexual inhibition owing to the threat of performance consequences and general behavioral inhibition Hypersexuality was found to be related to two broad personality factors that are characterized by emotional reactivity, risk taking, and impulsivity. The associated lack of sexual behavior control is influenced by sexual

  18. The effects of bariatric surgery – will understanding its mechanism render the knife unnecessary?

    OpenAIRE

    Browning, Kirsteen N; Hajnal, Andras

    2013-01-01

    The incidence of obesity is increasing worldwide at a dramatic rate, accompanied by an associated increase in comorbid conditions. Bariatric surgery is the most effective treatment for severe obesity with, until recently, Roux-en-Y gastric bypass (RYGB) being the most commonly performed procedures, yet the underlying mechanisms by which it induces a wide-array of beneficial effects remains obscure. From both basic science as well as clinical standpoints, there are several areas of current int...

  19. Understanding Freshness Perception from the Cognitive Mechanisms of Flavor: The Case of Beverages

    Science.gov (United States)

    Roque, Jérémy; Auvray, Malika; Lafraire, Jérémie

    2018-01-01

    Freshness perception has received recent consideration in the field of consumer science mainly because of its hedonic dimension, which is assumed to influence consumers’ preference and behavior. However, most studies have considered freshness as a multisensory attribute of food and beverage products without investigating the cognitive mechanisms at hand. In the present review, we endorse a slightly different perspective on freshness. We focus on (i) the multisensory integration processes that underpin freshness perception, and (ii) the top–down factors that influence the explicit attribution of freshness to a product by consumers. To do so, we exploit the recent literature on the cognitive underpinnings of flavor perception as a heuristic to better characterize the mechanisms of freshness perception in the particular case of beverages. We argue that the lack of consideration of particular instances of flavor, such as freshness, has resulted in a lack of consensus about the content and structure of different types of flavor representations. We then enrich these theoretical analyses, with a review of the cognitive mechanisms of flavor perception: from multisensory integration processes to the influence of top–down factors (e.g., attentional and semantic). We conclude that similarly to flavor, freshness perception is characterized by hybrid content, both perceptual and semantic, but that freshness has a higher-degree of specificity than flavor. In particular, contrary to flavor, freshness is characterized by specific functions (e.g., alleviation of oropharyngeal symptoms) and likely differs from flavor with respect to the weighting of each sensory contributor, as well as to its subjective location. Finally, we provide a comprehensive model of the cognitive mechanisms that underlie freshness perception. This model paves the way for further empirical research on particular instances of flavor, and will enable advances in the field of food and beverage cognition

  20. Investigating and improving student understanding of quantum mechanical observables and their corresponding operators in Dirac notation

    Science.gov (United States)

    Marshman, Emily; Singh, Chandralekha

    2018-01-01

    In quantum mechanics, for every physical observable, there is a corresponding Hermitian operator. According to the most common interpretation of quantum mechanics, measurement of an observable collapses the quantum state into one of the possible eigenstates of the operator and the corresponding eigenvalue is measured. Since Dirac notation is an elegant notation that is commonly used in upper-level quantum mechanics, it is important that students learn to express quantum operators corresponding to observables in Dirac notation in order to apply the quantum formalism effectively in diverse situations. Here we focus on an investigation that suggests that, even though Dirac notation is used extensively, many advanced undergraduate and PhD students in physics have difficulty expressing the identity operator and other Hermitian operators corresponding to physical observables in Dirac notation. We first describe the difficulties students have with expressing the identity operator and a generic Hermitian operator corresponding to an observable in Dirac notation. We then discuss how the difficulties found via written surveys and individual interviews were used as a guide in the development of a quantum interactive learning tutorial (QuILT) to help students develop a good grasp of these concepts. The QuILT strives to help students become proficient in expressing the identity operator and a generic Hermitian operator corresponding to an observable in Dirac notation. We also discuss the effectiveness of the QuILT based on in-class evaluations.

  1. Death matters: understanding heroin/opiate overdose risk and testing potential to prevent deaths.

    Science.gov (United States)

    Strang, John

    2015-07-01

    To describe work undertaken over a 20-year period, investigating overdose characteristics among survivors, effects of acute heroin administration, clustering of risk of overdose fatality and potential interventions to reduce this fatal outcome. Privileged-access interviewers obtained data from non-treatment as well as treatment samples; experimental study of drop in oxygen saturation following heroin/opiate injection; investigation of clusterings of death following prison release and treatment termination; and study of target populations as intervention work-force, including family as well as peers, and action research built into pilot implementation. Overdose has been experienced by about half of heroin/opiate misusers, with even higher proportions having witnessed an overdose, and with high levels of willingness to intervene. Heroin/opiates are associated with the majority of drug-related deaths, despite relative scarcity of use. Heroin injection causes a rapid drop in oxygen saturation, recovering only slowly over the next half hour. Deaths from drug overdose are greatly more likely on prison release and post-discharge from detoxification and other in-patient or residential settings. High levels of declared willingness to intervene are matched by active interventions. Both drug-using peers and family members show ability to improve knowledge and gain confidence from training. Audit study of take-home schemes finds approximately 10% of dispensed naloxone is used in real-life emergency situations. Overdose is experienced by most users, with heroin/opiates contributing disproportionately to drug overdose deaths. High-risk times (e.g. after prison release) are now clearly identified. Peers and family are a willing potential intervention work-force, but are rarely trained or given pre-supply of naloxone. Large-scale naloxone provision (e.g. national across Scotland and Wales) is now being delivered, while large-scale randomized trials (e.g. N-ALIVE prison

  2. Potential and limitations of using soil mapping information to understand landscape hydrology

    Directory of Open Access Journals (Sweden)

    F. Terribile

    2011-12-01

    Full Text Available This paper addresses the following points: how can whole soil data from normally available soil mapping databases (both conventional and those integrated by digital soil mapping procedures be usefully employed in hydrology? Answering this question requires a detailed knowledge of the quality and quantity of information embedded in and behind a soil map.

    To this end a description of the process of drafting soil maps was prepared (which is included in Appendix A of this paper. Then a detailed screening of content and availability of soil maps and database was performed, with the objective of an analytical evaluation of the potential and the limitations of soil data obtained through soil surveys and soil mapping. Then we reclassified the soil features according to their direct, indirect or low hydrologic relevance. During this phase, we also included information regarding whether this data was obtained by qualitative, semi-quantitative or quantitative methods. The analysis was performed according to two main points of concern: (i the hydrological interpretation of the soil data and (ii the quality of the estimate or measurement of the soil feature.

    The interaction between pedology and hydrology processes representation was developed through the following Italian case studies with different hydropedological inputs: (i comparative land evaluation models, by means of an exhaustive itinerary from simple to complex modelling applications depending on soil data availability, (ii mapping of soil hydrological behaviour for irrigation management at the district scale, where the main hydropedological input was the application of calibrated pedo-transfer functions and the Hydrological Function Unit concept, and (iii flood event simulation in an ungauged basin, with the functional aggregation of different soil units for a simplified soil pattern.

    In conclusion, we show that special care is required in handling data from soil

  3. Utilizing Toxicogenomic Data to Understand Chemical Mechanism of Action in Risk Assessment

    Science.gov (United States)

    A recent National Academy of Sciences report pointed to the strong potential for genomic technologies to contribute to the risk assessment process. The report, however, also acknowledged that neither has the full impact of genomic technology been realized nor has it been broadly ...

  4. Hyperglycemia Augments the Adipogenic Transdifferentiation Potential of Tenocytes and Is Alleviated by Cyclic Mechanical Stretch.

    Science.gov (United States)

    Wu, Yu-Fu; Huang, Yu-Ting; Wang, Hsing-Kuo; Yao, Chung-Chen Jane; Sun, Jui-Sheng; Chao, Yuan-Hung

    2017-12-28

    Diabetes mellitus is associated with damage to tendons, which may result from cellular dysfunction in response to a hyperglycemic environment. Tenocytes express diminished levels of tendon-associated genes under hyperglycemic conditions. In contrast, mechanical stretch enhances tenogenic differentiation. However, whether hyperglycemia increases the non-tenogenic differentiation potential of tenocytes and whether this can be mitigated by mechanical stretch remains elusive. We explored the in vitro effects of high glucose and mechanical stretch on rat primary tenocytes. Specifically, non-tenogenic gene expression, adipogenic potential, cell migration rate, filamentous actin expression, and the activation of signaling pathways were analyzed in tenocytes treated with high glucose, followed by the presence or absence of mechanical stretch. We analyzed tenocyte phenotype in vivo by immunohistochemistry using an STZ (streptozotocin)-induced long-term diabetic mouse model. High glucose-treated tenocytes expressed higher levels of the adipogenic transcription factors PPAR γ and C/EBPs. PPARγ was also highly expressed in diabetic tendons. In addition, increased adipogenic differentiation and decreased cell migration induced by high glucose implicated a fibroblast-to-adipocyte phenotypic change. By applying mechanical stretch to tenocytes in high-glucose conditions, adipogenic differentiation was repressed, while cell motility was enhanced, and fibroblastic morphology and gene expression profiles were strengthened. In part, these effects resulted from a stretch-induced activation of ERK (extracellular signal-regulated kinases) and a concomitant inactivation of Akt. Our results show that mechanical stretch alleviates the augmented adipogenic transdifferentiation potential of high glucose-treated tenocytes and helps maintain their fibroblastic characteristics. The alterations induced by high glucose highlight possible pathological mechanisms for diabetic tendinopathy

  5. Understanding the Atomic Scale Mechanisms that Control the Attainment of Ultralow Friction and Wear in Carbon-Based Materials

    Science.gov (United States)

    2016-01-16

    2015. 15. Invited. New Insights into Friction and Wear through In-Situ Nanotribology. Joint Symposium of the Surface Science Society of Japan and...and Carpick, R.W. Influence of Surface Passivation on the Friction and Wear Behavior of Ultrananocrystalline Diamond and Tetrahedral Amorphous Carbon...AFRL-AFOSR-JP-TR-2016-0053 Understanding the Atomic Scale Mechanism that controls the attainment of ultralow friction and wear in carbon based

  6. Arctic potential - Could more structured view improve the understanding of Arctic business opportunities?

    Science.gov (United States)

    Hintsala, Henna; Niemelä, Sami; Tervonen, Pekka

    2016-09-01

    The increasing interest towards the Arctic has been witnessed during the past decades. However, the commonly shared definitions of the Arctic key concepts have not yet penetrated national and international arenas for political and economic decision making. The lack of jointly defined framework has made different analyses related to the Arctic quite limited considering the magnitude of economic potential embedded in Arctic. This paper is built on the key findings of two separate, yet connected projects carried out in the Oulu region, Finland. In this paper's approach, the Arctic context has been defined as a composition of three overlapping layers. The first layer is the phenomenological approach to define the Arctic region. The second layer is the strategy-level analysis to define different Arctic paths as well as a national level description of a roadmap to Arctic specialization. The third layer is the operationalization of the first two layers to define the Arctic business context and business opportunities. The studied case from Oulu region indicates that alternative futures for the Arctic competences and business activities are in resemblance with only two of the four identified strategic pathways. Introduction of other pathways to regional level actors as credible and attractive options would require additional, systematic efforts.

  7. Conformational Explosion: Understanding the Complexity of the Para-Dialkylbenzene Potential Energy Surfaces

    Science.gov (United States)

    Mishra, Piyush; Hewett, Daniel M.; Zwier, Timothy S.

    2017-06-01

    This talk focuses on the single-conformation spectroscopy of small-chain para-dialkylbenzenes. This work builds on previous studies from our group on long-chain n-alkylbenzenes that identified the first folded structure in octylbenzene. The dialkylbenzenes are representative of a class of molecules that are common components of coal and aviation fuel and are known to be present in vehicle exhaust. We bring the molecules para-diethylbenzene, para-dipropylbenzene and para-dibutylbenzene into the gas phase and cool the molecules in a supersonic expansion. The jet-cooled molecules are then interrogated using laser-induced fluorescence excitation, fluorescence dip IR spectroscopy (FDIRS) and dispersed fluorescence. The LIF spectra in the S_{0}-S_{1} origin region show dramatic increases in the number of resolved transitions with increasing length of alkyl chains, reflecting an explosion in the number of unique low-energy conformations formed when two independent alkyl chains are present. Since the barriers to isomerization of the alkyl chain are similar in size, this results in an 'egg carton' shape to the potential energy surface. We use a combination of electronic frequency shift and alkyl CH stretch infrared spectra to generate a consistent set of conformational assignments.

  8. Understanding the nitrate coordination to Eu3+ ions in solution by potential of mean force calculations

    International Nuclear Information System (INIS)

    Duvail, M.; Guilbaud, Ph.

    2011-01-01

    Coordination of nitrate anions with lanthanoid cations (Ln 3+ ) in water, methanol and octanol-1 has been studied by means of molecular dynamics simulations with explicit polarization. Potential of mean force (PMF) profiles have been calculated for a mono-complex of lanthanoid nitrate (Ln(NO 3 ) 2+ ) in these solvents using umbrella-sampling molecular dynamics. In pure water, no difference in the nitrato coordination to lanthanoids (Nd 3+ , Eu 3+ and Dy 3+ ) is observed, i.e. the nitrate anion prefers the monodentate coordination, which promotes the salt dissociation. Then, the influence of the nature of the solvating molecules on the nitrato coordination to Eu 3+ has been investigated. PMF profiles point out that both monodentate and bidentate coordinations are stable in neat methanol, while in neat octanol, only the bidentate one is. MD simulations of Eu(NO 3 ) 3 in water-octanol mixtures with different concentrations of water have been then performed and confirm the importance of the water molecules' presence on the nitrate ion's coordination mode. (authors)

  9. Beyond EICA: understanding post-establishment evolution requires a broader evaluation of potential selection pressures

    Directory of Open Access Journals (Sweden)

    Joshua Atwood

    2011-10-01

    Full Text Available Research on post-establishment evolution in nonnative plant populations has focused almost exclusively on testing the Evolution of Increased Competitive Ability (EICA hypothesis, which posits that the lack of specialized herbivores in the invaded range drives evolution in nonnative plant populations. Fifteen years of conflicting EICA test results suggest that selection pressures other than specialized herbivory are important in driving post-establishment evolution in invasive species. Alternative hypotheses, such as the Evolution of Reduced Competitive Ability (ERCA hypothesis, have been proposed but have received little attention or testing. We argue that the lack of consensus across studies that test EICA may be due in part to the lack of consistent definitions and varying experimental design parameters, and that future research in this field would benefit from new methodological considerations. We examined previous work evaluating post-establishment evolution and evaluated the range of study systems and design parameters used in testing the EICA hypothesis. Our goal was to identify where different uses of ecological terms and different study parameters have hindered consensus and to suggest a path forward to move beyond EICA in post-establishment evolution studies. We incorporated these methods into a design framework that will increase data harmony across future studies and will facilitate examinations of any potential selection pressure driving evolution in the invaded range.

  10. Understanding and controlling the rest potential of carbon nanotube-based supercapacitors for energy density enhancement

    Science.gov (United States)

    Yoo, Young-Eun; Park, Jinwoo; Kim, Woong

    2018-03-01

    We present a novel method for enhancing the energy density of an electrical double layer capacitor (EDLC). Surface modification of single-walled carbon nanotube (SWNT) electrodes significantly affects the rest potential (E0) of EDLCs; acid treatment and polyethyleneimine (PEI) coating of SWNTs shift E0 toward more positive and more negative values, respectively. Adjusting E0 towards the center of the electrolyte stability window can increase the cell voltage and hence the energy density. PEI coating on SWNTs increases the cell voltage from 0.8 V to 1.7 V in tetrabutylammonium perchlorate (TBAP)/tetrahydrofuran (THF) electrolyte, and from 2.5 V to 3.1 V in tetraethylammonium tetrafluoroborate (TEABF4)/3-cyanopropionic acid methyl ester (CPAME), respectively. Moreover, PEI-SWNT EDLCs exhibit excellent cycling stability (92% of capacitance retention over 10000 cycles). We attribute the shift in E0 to a change in the Fermi level of SWNTs owing to the surface charge modification. Injection of electrical charge into PEI-SWNTs consistently yielded similar trends and thus validated our hypothesis. Our results may help to push various electrolytes that have been overlooked so far to new frontiers for obtaining high energy-density supercapacitors.

  11. The effects of students' reasoning abilities on conceptual understandings and problem-solving skills in introductory mechanics

    International Nuclear Information System (INIS)

    Ates, S; Cataloglu, E

    2007-01-01

    The purpose of this study was to determine if there are relationships among freshmen/first year students' reasoning abilities, conceptual understandings and problem-solving skills in introductory mechanics. The sample consisted of 165 freshmen science education prospective teachers (female = 86, male = 79; age range 17-21) who were enrolled in an introductory physics course. Data collection was done during the fall semesters in two successive years. At the beginning of each semester, the force concept inventory (FCI) and the classroom test of scientific reasoning (CTSR) were administered to assess students' initial understanding of basic concepts in mechanics and reasoning levels. After completing the course, the FCI and the mechanics baseline test (MBT) were administered. The results indicated that there was a significant difference in problem-solving skill test mean scores, as measured by the MBT, among concrete, formal and postformal reasoners. There were no significant differences in conceptual understanding levels of pre- and post-test mean scores, as measured by FCI, among the groups. The Benferroni post hoc comparison test revealed which set of reasoning levels showed significant difference for the MBT scores. No statistical difference between formal and postformal reasoners' mean scores was observed, while the mean scores between concrete and formal reasoners and concrete and postformal reasoners were statistically significantly different

  12. Understanding of bonding and mechanical characteristics of cementitious mineral tobermorite from first principles.

    Science.gov (United States)

    Tunega, Daniel; Zaoui, Ali

    2011-01-30

    This paper reports density functional theory study of the structural and mechanical properties of tobermorite mineral (9 Å phase) as one of the main component of cementitious materials in a concrete chemistry. Calculated bulk modulus and elastic constants reflect a relatively high resistance of the tobermorite structure with respect to external isostatic compression. Moreover, the elastic constants proved the anisotropic character of the tobermorite structure. The directions parallel to the axb plane are more resistant to the compression than the perpendicular direction. The largest contribution to this resistance comes from the "dreierketten" silicate chains. The bonding analysis linked macroscopic mechanical properties and the atomic structure of the tobermorite. It was found that polar covalent Si-O bonds are stiffer than iono-covalent Ca-O bonds. The SiO(4) tetrahedra are resistant with respect to the compression and the effect of external pressure is reflected by the large mutual tilting of these tetrahedra as it is shown by changes of the Si-O-Si bridging angles. Polyhedra with the seven-fold coordinated Ca(2+) cations undergo large structural changes. Especially, axial Ca-O bonds perpendicular to the axb plane are significantly shortened. Besides, it was shown that structural parameters, more or less in parallel orientation to the axb plane, are mainly responsible for the high resistance of the tobermorite structure to external pressure. The main mechanism of a dissipation of energy entered to the structure through the compression is proceeded by the tilting of the tetrahedra of the silicate chains and by large shortening of the axial Ca-O distances. Copyright © 2010 Wiley Periodicals, Inc.

  13. Understanding flocculation mechanism of graphene oxide for organic dyes from water: Experimental and molecular dynamics simulation

    Directory of Open Access Journals (Sweden)

    Jun Liu

    2015-11-01

    Full Text Available Flocculation treatment processes play an important role in water and wastewater pretreatment. Here we investigate experimentally and theoretically the possibility of using graphene oxide (GO as a flocculant to remove methylene blue (MB from water. Experimental results show that GO can remove almost all MB from aqueous solutions at its optimal dosages and molecular dynamics simulations indicate that MB cations quickly congregate around GO in water. Furthermore, PIXEL energy contribution analysis reveals that most of the strong interactions between GO and MB are of a van der Waals (London dispersion character. These results offer new insights for shedding light on the molecular mechanism of interaction between GO and organic pollutants.

  14. Understanding organometallic reaction mechanisms and catalysis experimental and computational tools computational and experimental tools

    CERN Document Server

    Ananikov, Valentin P

    2014-01-01

    Exploring and highlighting the new horizons in the studies of reaction mechanisms that open joint application of experimental studies and theoretical calculations is the goal of this book. The latest insights and developments in the mechanistic studies of organometallic reactions and catalytic processes are presented and reviewed. The book adopts a unique approach, exemplifying how to use experiments, spectroscopy measurements, and computational methods to reveal reaction pathways and molecular structures of catalysts, rather than concentrating solely on one discipline. The result is a deeper

  15. Monitoring tobacco brand websites to understand marketing strategies aimed at tobacco product users and potential users.

    Science.gov (United States)

    Escobedo, Patricia; Cruz, Tess Boley; Tsai, Kai-Ya; Allem, Jon-Patrick; Soto, Daniel W; Kirkpatrick, Matthew G; Pattarroyo, Monica; Unger, Jennifer B

    2017-09-11

    Limited information exists about strategies and methods used on brand marketing websites to transmit pro-tobacco messages to tobacco users and potential users. This study compared age verification methods, themes, interactive activities and links to social media across tobacco brand websites. This study examined 12 tobacco brand websites representing four tobacco product categories: cigarettes, cigar/cigarillos, smokeless tobacco, and e-cigarettes. Website content was analyzed by tobacco product category and data from all website visits (n = 699) were analyzed. Adult smokers (n=32) coded websites during a one-year period, indicating whether or not they observed any of 53 marketing themes, seven interactive activities, or five external links to social media sites. Most (58%) websites required online registration before entering, however e-cigarette websites used click-through age verification. Compared to cigarette sites, cigar/cigarillo sites were more likely to feature themes related to "party" lifestyle, and e-cigarette websites were much more likely to feature themes related to harm reduction. Cigarette sites featured greater levels of interactive content compared to other tobacco products. Compared to cigarette sites, cigar/cigarillo sites were more likely to feature activities related to events and music. Compared to cigarette sites, both cigar and e-cigarette sites were more likely to direct visitors to external social media sites. Marketing methods and strategies normalize tobacco use by providing website visitors with positive themes combined with interactive content, and is an area of future research. Moreover, all tobacco products under federal regulatory authority should be required to use more stringent age verification gates. Findings indicate the Food and Drug Administration (FDA) should require brand websites of all tobacco products under its regulatory authority use more stringent age verification gates by requiring all visitors be at least 18 years

  16. A Multiscale Understanding of the Thermodynamic and Kinetic Mechanisms of Laser Additive Manufacturing

    Directory of Open Access Journals (Sweden)

    Dongdong Gu

    2017-10-01

    Full Text Available Selective laser melting (SLM additive manufacturing (AM technology has become an important option for the precise manufacturing of complex-shaped metallic parts with high performance. The SLM AM process involves complicated physicochemical phenomena, thermodynamic behavior, and phase transformation as a high-energy laser beam melts loose powder particles. This paper provides multiscale modeling and coordinated control for the SLM of metallic materials including an aluminum (Al-based alloy (AlSi10Mg, a nickel (Ni-based super-alloy (Inconel 718, and ceramic particle-reinforced Al-based and Ni-based composites. The migration and distribution mechanisms of aluminium nitride (AlN particles in SLM-processed Al-based nanocomposites and the in situ formation of a gradient interface between the reinforcement and the matrix in SLM-processed tungsten carbide (WC/Inconel 718 composites were studied in the microscale. The laser absorption and melting/densification behaviors of AlSi10Mg and Inconel 718 alloy powder were disclosed in the mesoscale. Finally, the stress development during line-by-line localized laser scanning and the parameter-dependent control methods for the deformation of SLM-processed composites were proposed in the macroscale. Multiscale numerical simulation and experimental verification methods are beneficial in monitoring the complicated powder-laser interaction, heat and mass transfer behavior, and microstructural and mechanical properties development during the SLM AM process.

  17. Understanding the differing governance of EU emissions trading and renewable: feedback mechanisms and policy entrepreneurs

    Energy Technology Data Exchange (ETDEWEB)

    Boasson, Elin Lerum; Wettestad, Joergen

    2010-04-15

    This paper presents a comparative study of two central EU climate policies: the revised Emissions Trading System (ETS), and the revised Renewable Energy Directive (RES). Both were originally developed in the early 2000s and revised policies were adopted in December 2008. While the ETS from 2013 on will have a quite centralized and market-streamlined design, the revised RES stands forward as a more decentralized and technology-focused policy. Differing institutional feed-back mechanisms and related roles of policy entrepreneurs can shed considerable light on these policy differences. Due to member states' cautiousness and contrary to the preferences of the Commission, the initial ETS was designed as a rather decentralized and 'politicized' market system, creating a malfunctioning institutional dynamic. In the revision process, the Commission skillfully highlighted this ineffective dynamic to win support for a much more centralized and market-streamlined approach. In the case of RES, national technology-specific support schemes and the strong links between the renewable industry and member states promoted the converse outcome: decentralization and technology development. Members of the European Parliament utilized these mechanisms through policy networking, while the Commission successfully used developments within the global climate regime to induce some degree of centralization. (Author)

  18. Understanding the Mechanisms of Gold Shell Growth onto Polymer Microcapsules to Control Shell Thickness.

    Science.gov (United States)

    Tasker, Alison L; Hitchcock, James; Baxter, Elaine A; Cayre, Dr Olivier J; Biggs, Simon

    2017-07-04

    Polymer microcapsules have been used commercially for decades, however they have an inherent flaw which renders them impractical as a carrier of small, volatile molecules. The porous nature of the polymer shell allows for diffusion of the encapsulated molecules into the bulk. The use of metal shells is an innovative way to prevent undesired loss of small molecules from the core of microcapsules, however it is important, particularly when using expensive metals to ensure that the resulting shell is as thin as possible. Here we investigate the fundamental mechanisms controlling the gold shell thickness when a fragrance oil is encapsulated in a poly(methyl methacrylate) shell. We consider the distribution of the nanoparticles on the capsule surface, and from quantification of the adsorbed nanoparticle (NP) density and resulting shell thickness, we propose mechanisms to describe the gold shell growth for systems with high and low NP surface coverage. We suggest from our observations that the gold grows to fill in the gaps between NPs. At low NP concentrations, thicker metal shells form. We postulate that this is due to the low NP density on the surface, forcing the gold clusters to grow larger before they meet the adjacent ones. Thus, to grow the thinnest possible shells a densely packed monolayer of platinum nanoparticles is required on the capsule surface. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Understanding of carbon-based supercapacitors ageing mechanisms by electrochemical and analytical methods

    Science.gov (United States)

    Liu, Yinghui; Soucaze-Guillous, Benoît; Taberna, Pierre-Louis; Simon, Patrice

    2017-10-01

    In order to shed light on ageing mechanisms of Electrochemical Double Layer Capacitor (EDLC), two kinds of activated carbons are studied in tetraethyl ammonium tetrafluoroborate (Et4NBF4) in acetonitrile. In floating mode, it turns out that two different ageing mechanisms are observed, depending on the activated carbon electrode materials used. On one hand, carbon A exhibits a continuous capacitance and series resistance fall-off; on the other hand, for carbon B, only the series resistance degrades after ageing while the capacitance keeps unchanged. Additional electrochemical characterizations (Electrochemical Impedance Spectroscopy - EIS - and diffusion coefficient calculations) were carried out showing that carbon A's ageing behavior is suspected to be primarily related to the carbon degradation while for carbon B a passivation occurs leading to the formation of a Solid Electrolyte Interphase-Like (SEI-L) film. These hypotheses are supported by TG-IR and Raman spectroscopy analysis. The outcome forms the latter is an increase of carbon defects on carbon A on positive electrode.

  20. Atmospheric Compensation of Variations in Tropical Ocean Heat Transport: Understanding Mechanisms and Implications on Tectonic Timescales

    Science.gov (United States)

    Rencurrel, M. C.; Rose, B. E. J.

    2015-12-01

    The poleward transport of energy is a key aspect of the climate system, with surface ocean currents presently dominating the transport out of deep tropics. A classic study by Stone (1978) proposed that the total heat transport is determined by astronomical parameters and is highly insensitive to the detailed atmosphere-ocean dynamics. On the other hand, previous modeling work has shown that past continental configurations could have produced substantially different tropical ocean heat transport (OHT). How thoroughly does the atmosphere compensate for changes in ocean transport in terms of the top-of-atmosphere (TOA) radiative budget, what are the relevant mechanisms, and what are the consequences for surface temperature and climate on tectonic timescales? We examine these issues in a suite of aquaplanet GCM simulations subject to large prescribed variations in OHT. We find substantial but incomplete compensation, in which adjustment of the atmospheric Hadley circulation plays a key role. We then separate out the dynamical and thermodynamical components of the adjustment mechanism. Increased OHT tends to warm the mid- to high latitudes without cooling the tropics due asymmetries in radiative feedback processes. The warming is accompanied by hydrological cycle changes that are completely different from those driven by greenhouse gases, suggesting that drivers of past global change might be detectable from combinations of hydroclimate and temperature proxies.

  1. A New Alkali-Stable Phosphonium Cation Based on Fundamental Understanding of Degradation Mechanisms.

    Science.gov (United States)

    Zhang, Bingzi; Kaspar, Robert B; Gu, Shuang; Wang, Junhua; Zhuang, Zhongbin; Yan, Yushan

    2016-09-08

    Highly alkali-stable cationic groups are a critical component of hydroxide exchange membranes (HEMs). To search for such cations, we studied the degradation kinetics and mechanisms of a series of quaternary phosphonium (QP) cations. Benzyl tris(2,4,6-trimethoxyphenyl)phosphonium [BTPP-(2,4,6-MeO)] was determined to have higher alkaline stability than the benchmark cation, benzyl trimethylammonium (BTMA). A multi-step methoxy-triggered degradation mechanism for BTPP-(2,4,6-MeO) was proposed and verified. By replacing methoxy substituents with methyl groups, a superior QP cation, methyl tris(2,4,6-trimethylphenyl)phosphonium [MTPP-(2,4,6-Me)] was developed. MTPP-(2,4,6-Me) is one of the most stable cations reported to date, with <20 % degradation after 5000 h at 80 °C in a 1 m KOD in CD3 OD/D2 O (5:1 v/v) solution. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. Understanding the evolution of the windlass mechanism of the human foot from comparative anatomy: Insights, obstacles, and future directions.

    Science.gov (United States)

    Griffin, Nicole L; Miller, Charlotte E; Schmitt, Daniel; D'Août, Kristiaan

    2015-01-01

    Humans stand alone from other primates in that we propel our bodies forward on a relatively stiff and arched foot and do so by employing an anatomical arrangement of bones and ligaments in the foot that can operate like a "windlass." This is a significant evolutionary innovation, but it is currently unknown when during hominin evolution this mechanism developed and within what genera or species it originated. The presence of recently discovered fossils along with novel research in the past two decades have improved our understanding of foot mechanics in humans and other apes, making it possible to consider this question more fully. Here we review the main elements thought to be involved in the production of an effective, modern human-like windlass mechanism. These elements are the triceps surae, plantar aponeurosis, medial longitudinal arch, and metatarsophalangeal joints. We discuss what is presently known about the evolution of these features and the challenges associated with identifying each of these specific components and/or their function in living and extinct primates for the purpose of predicting the presence of the windlass mechanism in our ancestors. In some cases we recommend alternative pathways for inferring foot mechanics and for testing the hypothesis that the windlass mechanism evolved to increase the speed and energetic efficiency of bipedal gait in hominins. © 2014 Wiley Periodicals, Inc.

  3. Understanding mechanisms of solid-state phase transformations by probing nuclear materials

    Science.gov (United States)

    Banerjee, Srikumar; Donthula, Harish

    2018-04-01

    In this review a few examples will be cited to illustrate that a study on a specific nuclear material sometimes lead to a better understanding of scientific phenomena of broader interests. Zirconium alloys offer some unique opportunities in addressing fundamental issues such as (i) distinctive features between displacive and diffusional transformations, (ii) characteristics of shuffle and shear dominated displacive transformations and (iii) nature of mixed-mode transformations. Whether a transformation is of first or higher order?" is often raised while classifying it. There are rare examples, such as Ni-Mo alloys, in which during early stages of ordering the system experiences tendencies for both first order and second order transitions. Studies on the order-disorder transitions under a radiation environment have established the pathway for the evolution of ordering. These studies have also identified the temperature range over which the chemically ordered state remains stable in steady state under radiation.

  4. Understanding the desensitizing mechanism of olefin in explosives: shear slide of mixed HMX-olefin systems.

    Science.gov (United States)

    Zhang, Chaoyang; Cao, Xia; Xiang, Bin

    2012-04-01

    We simulated the shear slide behavior of typical mixed HMX-olefin systems and the effect of thickness of olefin layers (4-22 Å) on the behavior at a molecular level by considering two cases: bulk shear and interfacial shear. The results show that: (1) the addition of olefin into HMX can reduce greatly the shear sliding barriers relative to the pure HMX in the two cases, suggesting that the desensitizing mechanism of olefin is controlled dominantly by its good lubricating property; (2) the change of interaction energy in both systoles of shear slide is strongly dominated by van der Waals interaction; and (3) the thickness of olefin layers in the mixed explosives can influence its desensitizing efficiency. That is, the excessive thinness of olefin layers in the mixed explosive systems, for example, several angstroms, can lead to very high sliding barriers.

  5. Heat and mass transfer models to understand the drying mechanisms of a porous substrate.

    Science.gov (United States)

    Songok, Joel; Bousfield, Douglas W; Gane, Patrick A C; Toivakka, Martti

    2016-02-01

    While drying of paper and paper coatings is expensive, with significant energy requirements, the rate controlling mechanisms are not currently fully understood. Two two-dimensional models are used as a first approximation to predict the heat transfer during hot air drying and to evaluate the role of various parameters on the drying rates of porous coatings. The models help determine the structural limiting factors during the drying process, while applying for the first time the recently known values of coating thermal diffusivity. The results indicate that the thermal conductivity of the coating structure is not the controlling factor, but the drying rate is rather determined by the thermal transfer process at the structure surface. This underlines the need for ensuring an efficient thermal transfer from hot air to coating surface during drying, before considering further measures to increase the thermal conductivity of porous coatings.

  6. Understanding the neural mechanisms involved in sensory control of voice production.

    Science.gov (United States)

    Parkinson, Amy L; Flagmeier, Sabina G; Manes, Jordan L; Larson, Charles R; Rogers, Bill; Robin, Donald A

    2012-05-15

    Auditory feedback is important for the control of voice fundamental frequency (F0). In the present study we used neuroimaging to identify regions of the brain responsible for sensory control of the voice. We used a pitch-shift paradigm where subjects respond to an alteration, or shift, of voice pitch auditory feedback with a reflexive change in F0. To determine the neural substrates involved in these audio-vocal responses, subjects underwent fMRI scanning while vocalizing with or without pitch-shifted feedback. The comparison of shifted and unshifted vocalization revealed activation bilaterally in the superior temporal gyrus (STG) in response to the pitch shifted feedback. We hypothesize that the STG activity is related to error detection by auditory error cells located in the superior temporal cortex and efference copy mechanisms whereby this region is responsible for the coding of a mismatch between actual and predicted voice F0. Published by Elsevier Inc.

  7. The effects of bariatric surgery: will understanding its mechanism render the knife unnecessary?

    Science.gov (United States)

    Browning, Kirsteen N; Hajnal, Andras

    2014-01-01

    The incidence of obesity is increasing worldwide at a dramatic rate, accompanied by an associated increase in comorbid conditions. Bariatric surgery is the most effective treatment for morbid obesity with Roux-en-Y gastric bypass being the most commonly performed procedure, yet the underlying mechanisms by which it induces a wide-array of beneficial effects remains obscure. From basic science as well as clinical standpoints, there are several areas of current interest that warrant continued investigation. Several major focus areas have also emerged in current research that may guide future efforts in this field, particularly with regards to using novel, non-surgical approaches to mimic the success of bariatric surgery while minimizing its adverse side effects.

  8. Metal Oxide Nanomaterial QNAR Models: Available Structural Descriptors and Understanding of Toxicity Mechanisms

    Directory of Open Access Journals (Sweden)

    Jiali Ying

    2015-10-01

    Full Text Available Metal oxide nanomaterials are widely used in various areas; however, the divergent published toxicology data makes it difficult to determine whether there is a risk associated with exposure to metal oxide nanomaterials. The application of quantitative structure activity relationship (QSAR modeling in metal oxide nanomaterials toxicity studies can reduce the need for time-consuming and resource-intensive nanotoxicity tests. The nanostructure and inorganic composition of metal oxide nanomaterials makes this approach different from classical QSAR study; this review lists and classifies some structural descriptors, such as size, cation charge, and band gap energy, in recent metal oxide nanomaterials quantitative nanostructure activity relationship (QNAR studies and discusses the mechanism of metal oxide nanomaterials toxicity based on these descriptors and traditional nanotoxicity tests.

  9. Oxide Nanoparticle EUV (ONE) Photoresists: Current Understanding of the Unusual Patterning Mechanism

    KAUST Repository

    Jiang, Jing

    2015-01-01

    © 2015 SPST. In the past few years, industry has made significant progress to deliver a stable high power EUV scanner and a 100 W light source is now being tested on the manufacuring scale. The success of a high power EUV source demands a fast and high resolution EUV resist. However, chemcially amplied resists encounter unprecedented challenges beyond the 22 nm node due to resolution, roughness and sensitivity tradeoffs. Unless novel solutions for EUV resists are proposed and further optimzed, breakthroughs can hardly be achieved. Oxide nanoparticle EUV (ONE) resists stablized by organic ligands were originally proposed by Ober et al. Recently this work attracts more and more attention due to its extraordinanry EUV sensitivity. This new class of photoresist utilizes ligand cleavage with a ligand exchange mechanism to switch its solubilty for dual-tone patterning. Therefore, ligand selection of the nanoparticles is extremely important to its EUV performance.

  10. Understanding Central Mechanisms of Acupuncture Analgesia Using Dynamic Quantitative Sensory Testing: A Review

    Directory of Open Access Journals (Sweden)

    Jiang-Ti Kong

    2013-01-01

    Full Text Available We discuss the emerging translational tools for the study of acupuncture analgesia with a focus on psychophysical methods. The gap between animal mechanistic studies and human clinical trials of acupuncture analgesia calls for effective translational tools that bridge neurophysiological data with meaningful clinical outcomes. Temporal summation (TS and conditioned pain modulation (CPM are two promising tools yet to be widely utilized. These psychophysical measures capture the state of the ascending facilitation and the descending inhibition of nociceptive transmission, respectively. We review the basic concepts and current methodologies underlying these measures in clinical pain research, and illustrate their application to research on acupuncture analgesia. Finally, we highlight the strengths and limitations of these research methods and make recommendations on future directions. The appropriate addition of TS and CPM to our current research armamentarium will facilitate our efforts to elucidate the central analgesic mechanisms of acupuncture in clinical populations.

  11. Understanding the Broad Substrate Repertoire of Nitroreductase Based on Its Kinetic Mechanism*

    Science.gov (United States)

    Pitsawong, Warintra; Hoben, John P.; Miller, Anne-Frances

    2014-01-01

    The oxygen-insensitive nitroreductase from Enterobacter cloacae (NR) catalyzes two-electron reduction of nitroaromatics to the corresponding nitroso compounds and, subsequently, to hydroxylamine products. NR has an unusually broad substrate repertoire, which may be related to protein dynamics (flexibility) and/or a simple non-selective kinetic mechanism. To investigate the possible role of mechanism in the broad substrate repertoire of NR, the kinetics of oxidation of NR by para-nitrobenzoic acid (p-NBA) were investigated using stopped-flow techniques at 4 °C. The results revealed a hyperbolic dependence on the p-NBA concentration with a limiting rate of 1.90 ± 0.09 s−1, indicating one-step binding before the flavin oxidation step. There is no evidence for a distinct binding step in which specificity might be enforced. The reduction of p-NBA is rate-limiting in steady-state turnover (1.7 ± 0.3 s−1). The pre-steady-state reduction kinetics of NR by NADH indicate that NADH reduces the enzyme with a rate constant of 700 ± 20 s−1 and a dissociation constant of 0.51 ± 0.04 mm. Thus, we demonstrate simple transient kinetics in both the reductive and oxidative half-reactions that help to explain the broad substrate repertoire of NR. Finally, we tested the ability of NR to reduce para-hydroxylaminobenzoic acid, demonstrating that the corresponding amine does not accumulate to significant levels even under anaerobic conditions. Thus E. cloacae NR is not a good candidate for enzymatic production of aromatic amines. PMID:24706760

  12. Using Molecular Docking Analysis to Discovery Dregea sinensis Hemsl. Potential Mechanism of Anticancer, Antidepression, and Immunoregulation.

    Science.gov (United States)

    Liu, Xiujie; Shi, Yu; Deng, Yulin; Dai, Rongji

    2017-01-01

    Dregea sinensis Hemsl. plant of the genus Dregea volubilis (Asclepiadaceae), plays a vital role in anticancer, antidepression, and immunoregulation. Steroidal glycosides are the main constituents of this herb, which were significant biological active ingredients. The objective of this study is to recognize the mechanism of anticancer, antidepression, and immunoregulation of D. sinensis Hemsl. Seventy-two steroidal glycosides of D. sinensis Hemsl. were evaluated on the docking behavior of tumor-associated proteins (PI3K, Akt, mTOR), depression-related proteins (MAO-A, MAO-B) and immune-related proteins (tumor necrosis factor-α [TNF-α], tumor necrosis factor receptor 2 [TNFR2], interleukin-2Rα [IL-2Rα]) using Discovery Studio version 3.1 (Accelrys, San Diego, USA). The molecular docking analysis revealed that mostly steroidal glycosides of D. sinensis Hemsl. exhibited powerful interaction with the depression-related protein (MAO-A) and the immune-related proteins (TNFR2, IL-2Rα). Some ligands exhibited high binding energy for the tumor-associated proteins (PI3K, Akt, mTOR) and the immune-related protein (TNF-α), but MAO-B showed none interaction with the ligands. This study has paved better understanding of steroidal glycosides from D. sinensis Hemsl. as potential constituents to the prevention of associated cancer, depression and disorders of immunoregulation. The ligand database was consist of 72 steroidal glycosides from Dregea sinensis HemslSteroidal glycosides had the potential to dock with the tumor-associated proteins (PI3K, Akt, mTOR)Steroidal glycosides were bounded with MAO-A rather than MAO-B, accorded with the inhibitor selectivity of MAOs, can be considered as potent candidate inhibitors of MAO-A72 ligands got high interaction with TNFR2 and IL-2Rα, regard the steroidal glycoside as powerful candidate inhibitors of TNFR2 and IL-2Rα. Abbreviations used: PI3K: Phosphatidyl inositol 3-kinase; Akt: Protein kinase B; mTOR: Mammalian target of

  13. Exploring potential mechanisms of action of natalizumab in secondary progressive multiple sclerosis

    DEFF Research Database (Denmark)

    Sellebjerg, Finn; Cadavid, Diego; Steiner, Deborah

    2016-01-01

    progressive MS (SPMS), for which approved disease-modifying therapies are limited. In this review, we summarize the pathophysiological mechanisms involved in the development of SPMS and the rationale and clinical potential for natalizumab, which is currently approved for the treatment of relapsing forms of MS...

  14. Deciphering potential mechanisms of anaerobic soil disinfestation (ASD)-mediated control of Pratylenchus penetrans

    Science.gov (United States)

    Pratylenchus penetrans is a component of the apple replant disease (ARD) causal pathogen complex. The potential role for biological mechanisms contributing to ASD-mediated suppression of P. penetrans was examined in greenhouse study using orchard soil with a history of ARD. Populations of P. penetra...

  15. Contribution of transcranial magnetic stimulation to the understanding of cortical mechanisms involved in motor control.

    Science.gov (United States)

    Reis, Janine; Swayne, Orlando B; Vandermeeren, Yves; Camus, Mickael; Dimyan, Michael A; Harris-Love, Michelle; Perez, Monica A; Ragert, Patrick; Rothwell, John C; Cohen, Leonardo G

    2008-01-15

    Transcranial magnetic stimulation (TMS) was initially used to evaluate the integrity of the corticospinal tract in humans non-invasively. Since these early studies, the development of paired-pulse and repetitive TMS protocols allowed investigators to explore inhibitory and excitatory interactions of various motor and non-motor cortical regions within and across cerebral hemispheres. These applications have provided insight into the intracortical physiological processes underlying the functional role of different brain regions in various cognitive processes, motor control in health and disease and neuroplastic changes during recovery of function after brain lesions. Used in combination with neuroimaging tools, TMS provides valuable information on functional connectivity between different brain regions, and on the relationship between physiological processes and the anatomical configuration of specific brain areas and connected pathways. More recently, there has been increasing interest in the extent to which these physiological processes are modulated depending on the behavioural setting. The purpose of this paper is (a) to present an up-to-date review of the available electrophysiological data and the impact on our understanding of human motor behaviour and (b) to discuss some of the gaps in our present knowledge as well as future directions of research in a format accessible to new students and/or investigators. Finally, areas of uncertainty and limitations in the interpretation of TMS studies are discussed in some detail.

  16. Accelerating Our Understanding of Supernova Explosion Mechanism via Simulations and Visualizations with GenASiS

    Energy Technology Data Exchange (ETDEWEB)

    Budiardja, R. D. [University of Tennessee, Knoxville (UTK); Cardall, Christian Y [ORNL; Endeve, Eirik [ORNL

    2015-01-01

    Core-collapse supernovae are among the most powerful explosions in the Universe, releasing about 1053 erg of energy on timescales of a few tens of seconds. These explosion events are also responsible for the production and dissemination of most of the heavy elements, making life as we know it possible. Yet exactly how they work is still unresolved. One reason for this is the sheer complexity and cost of a self-consistent, multi-physics, and multi-dimensional core-collapse supernova simulation, which is impractical, and often impossible, even on the largest supercomputers we have available today. To advance our understanding we instead must often use simplified models, teasing out the most important ingredients for successful explosions, while helping us to interpret results from higher fidelity multi-physics models. In this paper we investigate the role of instabilities in the core-collapse supernova environment. We present here simulation and visualization results produced by our code GenASiS.

  17. Populations of models: A new approach for understanding the mechanisms of atrial fibrillation

    Energy Technology Data Exchange (ETDEWEB)

    Liberos, A.; Bueno-Orovio, A.; Rodrigo, M.; Ravens, U.; Hernandez, I.; Fernandez-Aviles, F.; Guillem, M.S.; Rodriguez, B.; Climent, A.M.

    2016-07-01

    Inter-subject variability explains the diverging effects to pharmacological treatments of AF reported in the literature. A population of 173 mathematical models of remodeled human atrial tissue with realistic inter–subject variability was developed based on action potential recordings of 149 patients diagnosed with AF. The ranges of 6 biomarkers measured from the patchclamp studies were appropriately covered. The resulting population shows that multiple combinations of variations in the ionic conductances result in AF models that cover the range of biomarkers measured experimentally. Introducing restrictions associated with pacing rate limits the number of models, restricts calcium transient amplitudes, and shows significant differences in the distribution of variation of parameters associated with INa, IKr and INaK ionic currents. Populations of models will improve the development of new antiarrhythmic treatments preventing undesired effects associated with differences between individuals. (Author)

  18. SANS study of understanding mechanism of cold gelation of globular proteins

    International Nuclear Information System (INIS)

    Chinchalikar, A. J.; Kumar, Sugam; Aswal, V. K.; Wagh, A. G.; Kohlbrecher, J.

    2014-01-01

    Small-angle neutron scattering (SANS) has been used to probe the evolution of interaction and the resultant structures in the cold gelation of globular proteins. The cold gelation involves two steps consisting of irreversible protein deformation by heating followed by some means (e.g. increasing ionic strength) to bring them together at room temperature. We have examined the role of different salts in cold gelation of preheated aqueous Bovine Serum Albumin (BSA) protein solutions. The interactions have been modeled by two Yukawa potential combining short-range attraction and long-range repulsion. We show that in step 1 (preheated temperature effect) the deformation of protein increases the magnitude of attractive interaction but not sufficient to induce gel. The attractive interaction is further enhanced in step 2 (salt effect) to result in gel formation. The salt effect is found to be strongly depending on the valency of the counterions. The gel structure has been characterized by the mass fractals

  19. Mechanical strain promotes osteoblast ECM formation and improves its osteoinductive potential

    Directory of Open Access Journals (Sweden)

    Guo Yong

    2012-10-01

    Full Text Available Abstract Background The extracellular matrix (ECM provides a supportive microenvironment for cells, which is suitable as a tissue engineering scaffold. Mechanical stimulus plays a significant role in the fate of osteoblast, suggesting that it regulates ECM formation. Therefore, we investigated the influence of mechanical stimulus on ECM formation and bioactivity. Methods Mouse osteoblastic MC3T3-E1 cells were cultured in cell culture dishes and stimulated with mechanical tensile strain. After removing the cells, the ECMs coated on dishes were prepared. The ECM protein and calcium were assayed and MC3T3-E1 cells were re-seeded on the ECM-coated dishes to assess osteoinductive potential of the ECM. Results The cyclic tensile strain increased collagen, bone morphogenetic protein 2 (BMP-2, BMP-4, and calcium levels in the ECM. Compared with the ECM produced by unstrained osteoblasts, those of mechanically stimulated osteoblasts promoted alkaline phosphatase activity, elevated BMP-2 and osteopontin levels and mRNA levels of runt-related transcriptional factor 2 (Runx2 and osteocalcin (OCN, and increased secreted calcium of the re-seeded MC3T3-E1 cells. Conclusion Mechanical strain promoted ECM production of osteoblasts in vitro, increased BMP-2/4 levels, and improved osteoinductive potential of the ECM. This study provided a novel method to enhance bioactivity of bone ECM in vitro via mechanical strain to osteoblasts.

  20. Understanding the growth mechanism of graphene on Ge/Si(001) surfaces

    Science.gov (United States)

    Dabrowski, J.; Lippert, G.; Avila, J.; Baringhaus, J.; Colambo, I.; Dedkov, Yu S.; Herziger, F.; Lupina, G.; Maultzsch, J.; Schaffus, T.; Schroeder, T.; Kot, M.; Tegenkamp, C.; Vignaud, D.; Asensio, M.-C.

    2016-01-01

    The practical difficulties to use graphene in microelectronics and optoelectronics is that the available methods to grow graphene are not easily integrated in the mainstream technologies. A growth method that could overcome at least some of these problems is chemical vapour deposition (CVD) of graphene directly on semiconducting (Si or Ge) substrates. Here we report on the comparison of the CVD and molecular beam epitaxy (MBE) growth of graphene on the technologically relevant Ge(001)/Si(001) substrate from ethene (C2H4) precursor and describe the physical properties of the films as well as we discuss the surface reaction and diffusion processes that may be responsible for the observed behavior. Using nano angle resolved photoemission (nanoARPES) complemented by transport studies and Raman spectroscopy as well as density functional theory (DFT) calculations, we report the direct observation of massless Dirac particles in monolayer graphene, providing a comprehensive mapping of their low-hole doped Dirac electron bands. The micrometric graphene flakes are oriented along two predominant directions rotated by 30° with respect to each other. The growth mode is attributed to the mechanism when small graphene “molecules” nucleate on the Ge(001) surface and it is found that hydrogen plays a significant role in this process. PMID:27531322

  1. Study and understanding of the ageing mechanisms in lead-calcium alloys

    International Nuclear Information System (INIS)

    Rossi, F.

    2006-12-01

    The data available in the literature about ageing and over-ageing of lead-calcium alloys are often incomplete and inconsistent. It is undoubtedly due to the experimental difficulties encountered to observe the structure transformations which are numerous. As a result there is a certain confusion among the results of the different authors. Moreover, small variations in the process parameters and chemical composition may have some influence on the alloy behaviour. This work enabled us to obtain a set of TTT diagrams, more realistic and accurate than the ones available in the literature. Experimental techniques developed (particularly the preservation of the cold chain with is essential for the guaranty of the results repeatability), enabled particularly the study of the first transformations and better control the five stages of ageing and over-ageing. Our work have enabled to determine precisely the kinetics and the mechanisms of the transformations. This work constitutes a thorough analysis of the ageing and over-ageing of theses alloys. (author)

  2. Comprehensive Understanding of Ductility Loss Mechanisms in Various Steels with External and Internal Hydrogen

    Science.gov (United States)

    Takakuwa, Osamu; Yamabe, Junichiro; Matsunaga, Hisao; Furuya, Yoshiyuki; Matsuoka, Saburo

    2017-11-01

    Hydrogen-induced ductility loss and related fracture morphologies are comprehensively discussed in consideration of the hydrogen distribution in a specimen with external and internal hydrogen by using 300-series austenitic stainless steels (Types 304, 316, 316L), high-strength austenitic stainless steels (HP160, XM-19), precipitation-hardened iron-based super alloy (A286), low-alloy Cr-Mo steel (JIS-SCM435), and low-carbon steel (JIS-SM490B). External hydrogen is realized by a non-charged specimen tested in high-pressure gaseous hydrogen, and internal hydrogen is realized by a hydrogen-charged specimen tested in air or inert gas. Fracture morphologies obtained by slow-strain-rate tensile tests (SSRT) of the materials with external or internal hydrogen could be comprehensively categorized into five types: hydrogen-induced successive crack growth, ordinary void formation, small-sized void formation related to the void sheet, large-sized void formation, and facet formation. The mechanisms of hydrogen embrittlement are broadly classified into hydrogen-enhanced decohesion (HEDE) and hydrogen-enhanced localized plasticity (HELP). In the HEDE model, hydrogen weakens interatomic bonds, whereas in the HELP model, hydrogen enhances localized slip deformations. Although various fracture morphologies are produced by external or internal hydrogen, these morphologies can be explained by the HELP model rather than by the HEDE model.

  3. Understanding the mechanism of iron sulfide-induced fouling in upgrading

    Energy Technology Data Exchange (ETDEWEB)

    Panchal, C.B. [United States Dept. of Energy, Chicago, IL (United States). Argonne National Laboratory

    2006-07-01

    This presentation investigated the underlying mechanisms of iron sulfide-induced fouling and coking in upgrading processes. Experiments to determine the effects of dissolved metals on the rate of fouling were reviewed. It was noted that the presence of species such as active sulfur and diolefins can enhance the effect of dissolved metals. An investigation of a high temperature fouling unit was then conducted to investigate the effect of iron acetate and theiphenol additions to stable heavy gas oil. The deposition rate became strongly dependent on temperature in the presence of the dissolved metals. Fouling deposit analyses from various parts of the refining process consistently showed high concentrations of iron and sulfur. It was observed that the threshold tube-wall temperature corresponded to the decomposition temperature of iron salts. A review of current literature indicated that there is little information on the interactive effects of the thermal stability of dissolved organo-metallic compounds and the reactivity of organic species in generating fouling precursors. The creation of a predictive model of threshold fouling and coking conditions was recommended. It was suggested that the model should be used during the design phases of furnaces and heat exchangers. Other recommendations included the use of on-line sensors to detect iron sulfide formulation; and the monitoring of coking furnaces. Blending guidelines to minimize the interactive effects of dissolved metals and active sulfur compounds were also presented. refs., tabs., figs.

  4. Toward understanding the mechanics of hovering in insects, hummingbirds and bats

    Science.gov (United States)

    Vejdani, Hamid; Boerma, David; Swartz, Sharon; Breuer, Kenneth

    2016-11-01

    We present results on the dynamical characteristics of two different mechanisms of hovering, corresponding to the behavior of hummingbirds and bats. Using a Lagrangian formulation, we have developed a dynamical model of a body (trunk) and two rectangular wings. The trunk has 3 degrees of freedom (x, z and pitch angle) and each wing has 3 modes of actuation: flapping, pronation/supination, and wingspan extension/flexion (only present for bats). Wings can be effectively massless (hummingbird and insect wings) or relatively massive (important in the case of bats). The aerodynamic drag and lift forces are calculated using a quasi-steady blade-element model. The regions of state space in which hovering is possible are computed by over an exhaustive range of parameters. The effect of wing mass is to shrink the phase space available for viable hovering and, in general, to require higher wingbeat frequency. Moreover, by exploring hovering energy requirements, we find that the pronation angle of the wings also plays a critical role. For bats, who have relatively heavy wings, we show wing extension and flexion is critical in order to maintain a plausible hovering posture with reasonable power requirements. Comparisons with biological data show good agreement with our model predictions.

  5. Recent advances in understanding the molecular mechanism of chloroplast photorelocation movement.

    Science.gov (United States)

    Kong, Sam-Geun; Wada, Masamitsu

    2014-04-01

    Plants are photosynthetic organisms that have evolved unique systems to adapt fluctuating environmental light conditions. In addition to well-known movement responses such as phototropism, stomatal opening, and nastic leaf movements, chloroplast photorelocation movement is one of the essential cellular responses to optimize photosynthetic ability and avoid photodamage. For these adaptations, chloroplasts accumulate at the areas of cells illuminated with low light (called accumulation response), while they scatter from the area illuminated with strong light (called avoidance response). Plant-specific photoreceptors (phototropin, phytochrome, and/or neochrome) mediate these dynamic directional movements in response to incident light position and intensity. Several factors involved in the mechanisms underlying the processes from light perception to actin-based movements have also been identified through molecular genetic approach. This review aims to discuss recent findings in the field relating to how chloroplasts move at molecular levels. This article is part of a Special Issue entitled: Dynamic and ultrastructure of bioenergetic membranes and their components. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Different approaches, one target: understanding cellular mechanisms of Parkinson's and Alzheimer's diseases.

    Science.gov (United States)

    Torrão, Andréa S; Café-Mendes, Cecilia C; Real, Caroline C; Hernandes, Marina S; Ferreira, Ana F B; Santos, Taisa O; Chaves-Kirsten, Gabriela P; Mazucanti, Caio H Y; Ferro, Emer S; Scavone, Cristoforo; Britto, Luiz R G

    2012-10-01

    Neurodegenerative disorders are undoubtedly an increasing problem in the health sciences, given the increase of life expectancy and occasional vicious life style. Despite the fact that the mechanisms of such diseases are far from being completely understood, a large number of studies that derive from both the basic science and clinical approaches have contributed substantial data in that direction. In this review, it is discussed several frontiers of basic research on Parkinson's and Alzheimer's diseases, in which research groups from three departments of the Institute of Biomedical Sciences of the University of São Paulo have been involved in a multidisciplinary effort. The main focus of the review involves the animal models that have been developed to study cellular and molecular aspects of those neurodegenerative diseases, including oxidative stress, insulin signaling and proteomic analyses, among others. We anticipate that this review will help the group determine future directions of joint research in the field and, more importantly, set the level of cooperation we plan to develop in collaboration with colleagues of the Nucleus for Applied Neuroscience Research that are mostly involved with clinical research in the same field.

  7. Partitioning CO2 fluxes with isotopologue measurements and modeling to understand mechanisms of forest carbon sequestration

    Energy Technology Data Exchange (ETDEWEB)

    Saleska, Scott [Univ. of Arizona, Tucson, AZ (United States); Davidson, Eric [Univ. of Arizona, Tucson, AZ (United States); Finzi, Adrien [Boston Univ., MA (United States); Wehr, Richdard [Harvard Univ., Cambridge, MA (United States); Moorcroft, Paul [Harvard Univ., Cambridge, MA (United States)

    2016-01-28

    1. Objectives This project combines automated in situ observations of the isotopologues of CO2 with root observations, novel experimental manipulations of belowground processes, and isotope-enabled ecosystem modeling to investigate mechanisms of below- vs. aboveground carbon sequestration at the Harvard Forest Environmental Measurements Site (EMS). The proposed objectives, which have now been largely accomplished, include: A. Partitioning of net ecosystem CO2 exchange (NEE) into photosynthesis and respiration using long-term continuous observations of the isotopic composition of NEE, and analysis of their dynamics ; B. Investigation of the influence of vegetation phenology on the timing and magnitude of carbon allocated belowground using measurements of root growth and indices of belowground autotrophic vs. heterotrophic respiration (via trenched plots and isotope measurements); C. Testing whether plant allocation of carbon belowground stimulates the microbial decomposition of soil organic matter, using in situ rhizosphere simulation experiments wherein realistic quantities of artificial isotopically-labeled exudates are released into the soil; and D. Synthesis and interpretation of the above data using the Ecosystem Demography Model 2 (ED2). 2. Highlights Accomplishments: • Our isotopic eddy flux record has completed its 5th full year and has been used to independently estimate ecosystem-scale respiration and photosynthesis. • Soil surface chamber isotopic flux measurements were carried out during three growing seasons, in conjunction with a trenching manipulation. Key findings to date (listed by objective): A. Partitioning of Net Ecosystem Exchange: 1. Ecosystem respiration is lower during the day than at night—the first robust evidence of the inhibition of leaf respiration by light (the “Kok effect”) at the ecosystem scale. 2. Because it neglects the Kok effect, the standard NEE partitioning approach overestimates ecosystem photosynthesis (by ~25%) and

  8. Recent Advances in Understanding Amino Acid Sensing Mechanisms that Regulate mTORC1

    Directory of Open Access Journals (Sweden)

    Liufeng Zheng

    2016-09-01

    Full Text Available The mammalian target of rapamycin (mTOR is the central regulator of mammalian cell growth, and is essential for the formation of two structurally and functionally distinct complexes: mTORC1 and mTORC2. mTORC1 can sense multiple cues such as nutrients, energy status, growth factors and hormones to control cell growth and proliferation, angiogenesis, autophagy, and metabolism. As one of the key environmental stimuli, amino acids (AAs, especially leucine, glutamine and arginine, play a crucial role in mTORC1 activation, but where and how AAs are sensed and signal to mTORC1 are not fully understood. Classically, AAs activate mTORC1 by Rag GTPases which recruit mTORC1 to lysosomes, where AA signaling initiates. Plasma membrane transceptor L amino acid transporter 1 (LAT1-4F2hc has dual transporter-receptor function that can sense extracellular AA availability upstream of mTORC1. The lysosomal AA sensors (PAT1 and SLC38A9 and cytoplasmic AA sensors (LRS, Sestrin2 and CASTOR1 also participate in regulating mTORC1 activation. Importantly, AAs can be sensed by plasma membrane receptors, like G protein-coupled receptor (GPCR T1R1/T1R3, and regulate mTORC1 without being transported into the cells. Furthermore, AA-dependent mTORC1 activation also initiates within Golgi, which is regulated by Golgi-localized AA transporter PAT4. This review provides an overview of the research progress of the AA sensing mechanisms that regulate mTORC1 activity.

  9. Understanding the mechanisms of cobalt-catalyzed hydrogenation and dehydrogenation reactions.

    Science.gov (United States)

    Zhang, Guoqi; Vasudevan, Kalyan V; Scott, Brian L; Hanson, Susan K

    2013-06-12

    Cobalt(II) alkyl complexes of aliphatic PNP pincer ligands have been synthesized and characterized. The cationic cobalt(II) alkyl complex [(PNHP(Cy))Co(CH2SiMe3)]BAr(F)4 (4) (PNHP(Cy) = bis[(2-dicyclohexylphosphino)ethyl]amine) is an active precatalyst for the hydrogenation of olefins and ketones and the acceptorless dehydrogenation of alcohols. To elucidate the possible involvement of the N-H group on the pincer ligand in the catalysis via a metal-ligand cooperative interaction, the reactivities of 4 and [(PNMeP(Cy))Co(CH2SiMe3)]BAr(F)4 (7) were compared. Complex 7 was found to be an active precatalyst for the hydrogenation of olefins. In contrast, no catalytic activity was observed using 7 as a precatalyst for the hydrogenation of acetophenone under mild conditions. For the acceptorless dehydrogenation of 1-phenylethanol, complex 7 displayed similar activity to complex 4, affording acetophenone in high yield. When the acceptorless dehydrogenation of 1-phenylethanol with precatalyst 4 was monitored by NMR spectroscopy, the formation of the cobalt(III) acetylphenyl hydride complex [(PNHP(Cy))Co(III)(κ(2)-O,C-C6H4C(O)CH3)(H)]BAr(F)4 (13) was detected. Isolated complex 13 was found to be an effective catalyst for the acceptorless dehydrogenation of alcohols, implicating 13 as a catalyst resting state during the alcohol dehydrogenation reaction. Complex 13 catalyzed the hydrogenation of styrene but showed no catalytic activity for the room temperature hydrogenation of acetophenone. These results support the involvement of metal-ligand cooperativity in the room temperature hydrogenation of ketones but not the hydrogenation of olefins or the acceptorless dehydrogenation of alcohols. Mechanisms consistent with these observations are presented for the cobalt-catalyzed hydrogenation of olefins and ketones and the acceptorless dehydrogenation of alcohols.

  10. Toward an understanding of the molecular mechanisms of barnacle larval settlement: A comparative transcriptomic approach

    KAUST Repository

    Chen, Zhang-Fan

    2011-07-29

    Background: The barnacle Balanus amphitrite is a globally distributed biofouler and a model species in intertidal ecology and larval settlement studies. However, a lack of genomic information has hindered the comprehensive elucidation of the molecular mechanisms coordinating its larval settlement. The pyrosequencing-based transcriptomic approach is thought to be useful to identify key molecular changes during larval settlement. Methodology and Principal Findings: Using 454 pyrosequencing, we collected totally 630,845 reads including 215,308 from the larval stages and 415,537 from the adults; 23,451 contigs were generated while 77,785 remained as singletons. We annotated 31,720 of the 92,322 predicted open reading frames, which matched hits in the NCBI NR database, and identified 7,954 putative genes that were differentially expressed between the larval and adult stages. Of these, several genes were further characterized with quantitative real-time PCR and in situ hybridization, revealing some key findings: 1) vitellogenin was uniquely expressed in late nauplius stage, suggesting it may be an energy source for the subsequent non-feeding cyprid stage; 2) the locations of mannose receptors suggested they may be involved in the sensory system of cyprids; 3) 20 kDa-cement protein homologues were expressed in the cyprid cement gland and probably function during attachment; and 4) receptor tyrosine kinases were expressed higher in cyprid stage and may be involved in signal perception during larval settlement. Conclusions: Our results provide not only the basis of several new hypotheses about gene functions during larval settlement, but also the availability of this large transcriptome dataset in B. amphitrite for further exploration of larval settlement and developmental pathways in this important marine species. © 2011 Chen et al.

  11. A review and framework for understanding the potential impact of poor solid waste management on health in developing countries.

    Science.gov (United States)

    Ziraba, Abdhalah K; Haregu, Tilahun Nigatu; Mberu, Blessing

    2016-01-01

    The increase in solid waste generated per capita in Africa has not been accompanied by a commensurate growth in the capacity and funding to manage it. It is reported that less than 30% of urban waste in developing countries is collected and disposed appropriately. The implications of poorly managed waste on health are numerous and depend on the nature of the waste, individuals exposed, duration of exposure and availability of interventions for those exposed. To present a framework for understanding the linkages between poor solid waste management, exposure and associated adverse health outcomes. The framework will aid understanding of the relationships, interlinkages and identification of the potential points for intervention. Development of the framework was informed by a review of literature on solid waste management policies, practices and its impact on health in developing countries. A configurative synthesis of literature was applied to develop the framework. Several iterations of the framework were reviewed by experts in the field. Each linkage and outcomes are described in detail as outputs of this study. The resulting framework identifies groups of people at a heightened risk of exposure and the potential health consequences. Using the iceberg metaphor, the framework illustrates the pathways and potential burden of ill-health related to solid waste that is hidden but rapidly unfolding with our inaction. The existing evidence on the linkage between poor solid waste management and adverse health outcomes calls to action by all stakeholders in understanding, prioritizing, and addressing the issue of solid waste in our midst to ensure that our environment and health are preserved. A resulting framework developed in this study presents a clearer picture of the linkages between poor solid waste management and could guide research, policy and action.

  12. Nano-diamonds surface modifications: understanding of electron exchange mechanisms and evidence of a therapeutic effect

    International Nuclear Information System (INIS)

    Petit, Tristan

    2013-01-01

    In this thesis, a therapeutic effect of nano-diamonds (NDs) has been evidenced by investigating the role of NDs surface chemistry on their electronic properties. More precisely, the generation of reactive oxygen species from detonation NDs under ionizing radiation, which could improve current radiotherapy treatments, has been demonstrated. To this end, surface treatments facilitating electron transfer from NDs to their environment, namely hydrogenation and surface graphitization, were developed. Experimental conditions ensuring an efficient hydrogenation by hydrogen plasma were determined under ultrahigh vacuum, before being used to prepare large quantities of NDs in powder phase. A similar procedure was applied to the surface graphitization of NDs, performed by annealing under vacuum at high temperature. The impact of such surface treatments on the electronic interaction properties of NDs has been investigated under ambient air and after dispersion in water. These surface treatments induce a positive Zeta potential to NDs in water, which origin has been discussed. Finally, their interactions with human tumor cells were observed. Radiosensitization of tumor cells using NDs under gamma irradiation was demonstrated, opening new perspectives for NDs in nano-medicine. (author) [fr

  13. Potential neural mechanisms underlying the effectiveness of early intervention for children with autism spectrum disorder

    Science.gov (United States)

    Sullivan, Katherine; Stone, Wendy L.; Dawson, Geraldine

    2014-01-01

    Although evidence supports the efficacy of early intervention for improving outcomes for children with autism spectrum disorder (ASD), the mechanisms underlying their effectiveness remain poorly understood. This paper reviews the research literature on the neural bases of the early core deficits in ASD and proposes three key features of early intervention related to the neural mechanisms that may contribute to its effectiveness in improving deficit areas. These features include (1) the early onset of intensive intervention which capitalizes on the experience-expectant plasticity of the immature brain, (2) the use of treatment strategies that address core deficits in social motivation through an emphasis on positive social engagement and arousal modulation, and (3) promotion of complex neural networks and connectivity through thematic, multi-sensory and multi-domain teaching approaches. Understanding the mechanisms of effective early intervention will enable us to identify common or foundational active ingredients for promoting optimal outcomes in children with ASD. PMID:25108609

  14. Understanding the mechanisms of solid-water reactions through analysis of surface topography.

    Science.gov (United States)

    Bandstra, Joel Z; Brantley, Susan L

    2015-12-01

    The topography of a reactive surface contains information about the reactions that form or modify the surface and, therefore, it should be possible to characterize reactivity using topography parameters such as surface area, roughness, or fractal dimension. As a test of this idea, we consider a two-dimensional (2D) lattice model for crystal dissolution and examine a suite of topography parameters to determine which may be useful for predicting rates and mechanisms of dissolution. The model is based on the assumption that the reactivity of a surface site decreases with the number of nearest neighbors. We show that the steady-state surface topography in our model system is a function of, at most, two variables: the ratio of the rate of loss of sites with two neighbors versus three neighbors (d(2)/d(3)) and the ratio of the rate of loss of sites with one neighbor versus three neighbors (d(1)/d(3)). This means that relative rates can be determined from two parameters characterizing the topography of a surface provided that the two parameters are independent of one another. It also means that absolute rates cannot be determined from measurements of surface topography alone. To identify independent sets of topography parameters, we simulated surfaces from a broad range of d(1)/d(3) and d(2)/d(3) and computed a suite of common topography parameters for each surface. Our results indicate that the fractal dimension D and the average spacing between steps, E[s], can serve to uniquely determine d(1)/d(3) and d(2)/d(3) provided that sufficiently strong correlations exist between the steps. Sufficiently strong correlations exist in our model system when D>1.5 (which corresponds to D>2.5 for real 3D reactive surfaces). When steps are uncorrelated, surface topography becomes independent of step retreat rate and D is equal to 1.5. Under these conditions, measures of surface topography are not independent and any single topography parameter contains all of the available mechanistic

  15. Coping with the Forced Swim Stressor: Towards Understanding an Adaptive Mechanism.

    Science.gov (United States)

    de Kloet, E R; Molendijk, M L

    2016-01-01

    In the forced swim test (FST) rodents progressively show increased episodes of immobility if immersed in a beaker with water from where escape is not possible. In this test, a compound qualifies as a potential antidepressant if it prevents or delays the transition to this passive (energy conserving) behavioural style. In the past decade however the switch from active to passive "coping" was used increasingly to describe the phenotype of an animal that has been exposed to a stressful history and/or genetic modification. A PubMed analysis revealed that in a rapidly increasing number of papers (currently more than 2,000) stress-related immobility in the FST is labeled as a depression-like phenotype. In this contribution we will examine the different phases of information processing during coping with the forced swim stressor. For this purpose we focus on the action of corticosterone that is mediated by the closely related mineralocorticoid receptors (MR) and glucocorticoid receptors (GR) in the limbic brain. The evidence available suggests a model in which we propose that the limbic MR-mediated response selection operates in complementary fashion with dopaminergic accumbens/prefrontal executive functions to regulate the transition between active and passive coping styles. Upon rescue from the beaker the preferred, mostly passive, coping style is stored in the memory via a GR-dependent action in the hippocampal dentate gyrus. It is concluded that the rodent's behavioural response to a forced swim stressor does not reflect depression. Rather the forced swim experience provides a unique paradigm to investigate the mechanistic underpinning of stress coping and adaptation.

  16. Coping with the Forced Swim Stressor: Towards Understanding an Adaptive Mechanism

    Directory of Open Access Journals (Sweden)

    E. R. de Kloet

    2016-01-01

    Full Text Available In the forced swim test (FST rodents progressively show increased episodes of immobility if immersed in a beaker with water from where escape is not possible. In this test, a compound qualifies as a potential antidepressant if it prevents or delays the transition to this passive (energy conserving behavioural style. In the past decade however the switch from active to passive “coping” was used increasingly to describe the phenotype of an animal that has been exposed to a stressful history and/or genetic modification. A PubMed analysis revealed that in a rapidly increasing number of papers (currently more than 2,000 stress-related immobility in the FST is labeled as a depression-like phenotype. In this contribution we will examine the different phases of information processing during coping with the forced swim stressor. For this purpose we focus on the action of corticosterone that is mediated by the closely related mineralocorticoid receptors (MR and glucocorticoid receptors (GR in the limbic brain. The evidence available suggests a model in which we propose that the limbic MR-mediated response selection operates in complementary fashion with dopaminergic accumbens/prefrontal executive functions to regulate the transition between active and passive coping styles. Upon rescue from the beaker the preferred, mostly passive, coping style is stored in the memory via a GR-dependent action in the hippocampal dentate gyrus. It is concluded that the rodent’s behavioural response to a forced swim stressor does not reflect depression. Rather the forced swim experience provides a unique paradigm to investigate the mechanistic underpinning of stress coping and adaptation.

  17. Dynamic Action Potential Restitution Contributes to Mechanical Restitution in Right Ventricular Myocytes From Pulmonary Hypertensive Rats.

    Science.gov (United States)

    Hardy, Matthew E L; Pervolaraki, Eleftheria; Bernus, Olivier; White, Ed

    2018-01-01

    We investigated the steepened dynamic action potential duration (APD) restitution of rats with pulmonary artery hypertension (PAH) and right ventricular (RV) failure and tested whether the observed APD restitution properties were responsible for negative mechanical restitution in these myocytes. PAH and RV failure were provoked in male Wistar rats by a single injection of monocrotaline (MCT) and compared with saline-injected animals (CON). Action potentials were recorded from isolated RV myocytes at stimulation frequencies between 1 and 9 Hz. Action potential waveforms recorded at 1 Hz were used as voltage clamp profiles (action potential clamp) at stimulation frequencies between 1 and 7 Hz to evoke rate-dependent currents. Voltage clamp profiles mimicking typical CON and MCT APD restitution were applied and cell shortening simultaneously monitored. Compared with CON myocytes, MCT myocytes were hypertrophied; had less polarized diastolic membrane potentials; had action potentials that were triggered by decreased positive current density and shortened by decreased negative current density; APD was longer and APD restitution steeper. APD90 restitution was unchanged by exposure to the late Na + -channel blocker (5 μM) ranolazine or the intracellular Ca 2+ buffer BAPTA. Under AP clamp, stimulation frequency-dependent inward currents were smaller in MCT myocytes and were abolished by BAPTA. In MCT myocytes, increasing stimulation frequency decreased contraction amplitude when depolarization duration was shortened, to mimic APD restitution, but not when depolarization duration was maintained. We present new evidence that the membrane potential of PAH myocytes is less stable than normal myocytes, being more easily perturbed by external currents. These observations can explain increased susceptibility to arrhythmias. We also present novel evidence that negative APD restitution is at least in part responsible for the negative mechanical restitution in PAH myocytes. Thus

  18. AMBIENT CARBONATION of MINING RESIDUES: Understanding the Mechanisms and Optimization of Direct Carbon Dioxide Mineral Sequestration

    Science.gov (United States)

    Assima, G. P.; Larachi, F.; Molson, J. W.; Beaudoin, G.

    2013-12-01

    The huge amounts (GTs) of ultramafic mining residues (UMRs) produced by mining activities around the world and accumulated in multi-square-kilometer stockpiles are stimulating a vivid interest regarding their possible use as a stable and permanent sink for CO2. Virtually costless and often found crushed and / or ground, UMRs are being considered as ideal candidates for atmospheric CO2 mitigation. The present work, therefore, explores the potential of several UMRs available in Quebec (Thetford Mines, Asbestos, Nunavik, Amos, Otish Mountains), for carbonation under ambient conditions, as a cost-effective alternative to remove low-concentration CO2 from the atmosphere and alleviate global warming. Several experimental reactors have been built to specifically simulate various climatic changes at the laboratory scale. The impact of various environmental conditions to which the residues are subjected to in their storage location, including temperature variations, precipitation, flooding, drought, changing water saturation, oxygen gradient and CO2 diffusion have been thoroughly studied. Dry and heavy-rain periods are unsuitable for efficient CO2 sequestration. Low liquid saturation within UMRs pores favors carbonation by combining fast percolation of gaseous CO2, rapid dissemination of CO2 dissolved species and creation of highly reactive sites throughout the mining residue pile. Partly saturated samples were also found to exhibit lower gaseous CO2 breakthrough times across the mining residues. Warm periods significantly accelerate the rate of CO2 uptake as compared to cold periods, which, in contrast are characterized by heat generation levels that could possibly be exploited by low temperature geothermal systems. A temperature rise from 10 to 40 °C was accompanied by a ten-fold increase in initial reaction rate. The carbonation reaction caused a rise in UMRs temperature up to 4.9°C during experiments at a 10°C. The presence of oxygen in the reaction medium induces

  19. Potential mechanisms of phthalate ester embryotoxicity in the abalone Haliotis diversicolor supertexta

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Jin [L-304, Life Sciences Division, Graduate School at Shenzhen, Tsinghua University, Shenzhen University Town, Xili, Shenzhen City 518055 (China); Cai Zhonghua, E-mail: caizh@sz.tsinghua.edu.cn [L-304, Life Sciences Division, Graduate School at Shenzhen, Tsinghua University, Shenzhen University Town, Xili, Shenzhen City 518055 (China); Key Laboratory of Aquatic-Ecology, Tianjin Agricultural University, Lishui Road 112, Tianjin 300384 (China); Xing Kezhi [Key Laboratory of Aquatic-Ecology, Tianjin Agricultural University, Lishui Road 112, Tianjin 300384 (China)

    2011-05-15

    The effects and associated toxicological mechanisms of five phthalate esters (PAEs) on abalone embryonic development were investigated by exposing the embryos to a range of PAEs concentrations (0.05, 0.2, 2 and 10 {mu}g/mL). The results showed that PAEs could significantly reduce embryo hatchability, increase developmental malformations, and suppress the metamorphosis of abalone larvae. The possible toxicological mechanisms of PAEs to abalone embryos included, affecting the Na{sup +}-K{sup +}-pump and Ca{sup 2+}-Mg{sup 2+}-pump activities, altering the peroxidase (POD) level and the malondialdehyde (MDA) production, damaging the extraembryonic membranes structure, as well as disrupting endocrine-related genes (gpx, cyp3a, and 17{beta}-hsd 12) expression properties. Taken together, this work showed that PAEs adversely affected the embryonic ontogeny of abalone. The abilities of PAEs affecting the osmoregulation, inducing oxidative stress, damaging embryo envelope structure, and causing physiological homeostasis disorder, are likely to be a part of the common mechanisms responsible for their embryonic toxicity. - Highlights: > PAEs affected abalone hatchability, morphogenesis and metamorphosis behavior. > The toxicity of the five PAEs to embryogenesis was ranked as DBP > DEP > DMP > DOP > DEHP. > The osmoregulation disorder and oxidative damage are the potential mechanisms. - Potential mechanisms of PAEs on abalone embryogenesis are osmoregulation disorder, oxidative damage and physiological dysfunction.

  20. Potential mechanisms linking probiotics to diabetes: a narrative review of the literature

    Directory of Open Access Journals (Sweden)

    Maryam Miraghajani

    Full Text Available ABSTRACT CONTEXT AND OBJECTIVE: Some studies have suggested a wide range of possible mechanisms through which probiotics may play a role in diabetes prevention and treatment. However, the underlying mechanisms are not fully understood. We conducted this study to review the potential mechanisms suggested for the effect of probiotics in diabetes. DESIGN AND SETTING: Narrative review conducted at the Food Security Research Center of Isfahan. METHODS: A search in the electronic databases MEDLINE (PubMed, Cochrane Library, Web of Science and Google scholar was performed up to October 2016. RESULTS: The initial search yielded 1214 reports. After removing duplicates, 704 titles and abstracts were screened. Finally, out of 83 full-text articles that were reviewed for eligibility, 30 articles were included in the final analysis. The anti-diabetic mechanisms for probiotics reported encompass intraluminal and direct effects on the intestinal mucosa and microbiota (n = 13, anti-inflammatory and immunomodulatory effects (n = 10, antioxidative effects (n = 5, effects on endoplasmic reticulum (ER stress and expression of genes involved in glucose homeostasis and insulin resistance (n = 6, with some studies pointing to more than one mechanism. CONCLUSION: The results may throw some light on the capacity of probiotics as a novel approach towards controlling diabetes. However, further human studies are warranted to elucidate and confirm the potential role of probiotics in diabetes prevention and treatment. Also, it needs to be ascertained whether the effectiveness of probiotics in diabetes prevention and treatment is dependent on the strain of the microorganisms.

  1. Understanding dental CAD/CAM for restorations - dental milling machines from a mechanical engineering viewpoint. Part A: chairside milling machines.

    Science.gov (United States)

    Lebon, Nicolas; Tapie, Laurent; Duret, Francois; Attal, Jean-Pierre

    2016-01-01

    The dental milling machine is an important device in the dental CAD/CAM chain. Nowadays, dental numerical controlled (NC) milling machines are available for dental surgeries (chairside solution). This article provides a mechanical engineering approach to NC milling machines to help dentists understand the involvement of technology in digital dentistry practice. First, some technical concepts and definitions associated with NC milling machines are described from a mechanical engineering viewpoint. The technical and economic criteria of four chairside dental NC milling machines that are available on the market are then described. The technical criteria are focused on the capacities of the embedded technologies of these milling machines to mill both prosthetic materials and types of shape restorations. The economic criteria are focused on investment costs and interoperability with third-party software. The clinical relevance of the technology is assessed in terms of the accuracy and integrity of the restoration.

  2. Quantum interactive learning tutorial on the double-slit experiment to improve student understanding of quantum mechanics

    Directory of Open Access Journals (Sweden)

    Ryan Sayer

    2017-05-01

    Full Text Available Learning quantum mechanics is challenging, even for upper-level undergraduate and graduate students. Research-validated interactive tutorials that build on students’ prior knowledge can be useful tools to enhance student learning. We have been investigating student difficulties with quantum mechanics pertaining to the double-slit experiment in various situations that appear to be counterintuitive and contradict classical notions of particles and waves. For example, if we send single electrons through the slits, they may behave as a “wave” in part of the experiment and as a “particle” in another part of the same experiment. Here we discuss the development and evaluation of a research-validated Quantum Interactive Learning Tutorial (QuILT which makes use of an interactive simulation to improve student understanding of the double-slit experiment and strives to help students develop a good grasp of foundational issues in quantum mechanics. We discuss common student difficulties identified during the development and evaluation of the QuILT and analyze the data from the pretest and post test administered to the upper-level undergraduate and first-year physics graduate students before and after they worked on the QuILT to assess its effectiveness. These data suggest that on average, the QuILT was effective in helping students develop a more robust understanding of foundational concepts in quantum mechanics that defy classical intuition using the context of the double-slit experiment. Moreover, upper-level undergraduates outperformed physics graduate students on the post test. One possible reason for this difference in performance may be the level of student engagement with the QuILT due to the grade incentive. In the undergraduate course, the post test was graded for correctness while in the graduate course, it was only graded for completeness.

  3. Quantum interactive learning tutorial on the double-slit experiment to improve student understanding of quantum mechanics

    Science.gov (United States)

    Sayer, Ryan; Maries, Alexandru; Singh, Chandralekha

    2017-06-01

    Learning quantum mechanics is challenging, even for upper-level undergraduate and graduate students. Research-validated interactive tutorials that build on students' prior knowledge can be useful tools to enhance student learning. We have been investigating student difficulties with quantum mechanics pertaining to the double-slit experiment in various situations that appear to be counterintuitive and contradict classical notions of particles and waves. For example, if we send single electrons through the slits, they may behave as a "wave" in part of the experiment and as a "particle" in another part of the same experiment. Here we discuss the development and evaluation of a research-validated Quantum Interactive Learning Tutorial (QuILT) which makes use of an interactive simulation to improve student understanding of the double-slit experiment and strives to help students develop a good grasp of foundational issues in quantum mechanics. We discuss common student difficulties identified during the development and evaluation of the QuILT and analyze the data from the pretest and post test administered to the upper-level undergraduate and first-year physics graduate students before and after they worked on the QuILT to assess its effectiveness. These data suggest that on average, the QuILT was effective in helping students develop a more robust understanding of foundational concepts in quantum mechanics that defy classical intuition using the context of the double-slit experiment. Moreover, upper-level undergraduates outperformed physics graduate students on the post test. One possible reason for this difference in performance may be the level of student engagement with the QuILT due to the grade incentive. In the undergraduate course, the post test was graded for correctness while in the graduate course, it was only graded for completeness.

  4. Deoxyribonucleic Acid Damage and Repair: Capitalizing on Our Understanding of the Mechanisms of Maintaining Genomic Integrity for Therapeutic Purposes

    Directory of Open Access Journals (Sweden)

    Jolene Michelle Helena

    2018-04-01

    Full Text Available Deoxyribonucleic acid (DNA is the self-replicating hereditary material that provides a blueprint which, in collaboration with environmental influences, produces a structural and functional phenotype. As DNA coordinates and directs differentiation, growth, survival, and reproduction, it is responsible for life and the continuation of our species. Genome integrity requires the maintenance of DNA stability for the correct preservation of genetic information. This is facilitated by accurate DNA replication and precise DNA repair. DNA damage may arise from a wide range of both endogenous and exogenous sources but may be repaired through highly specific mechanisms. The most common mechanisms include mismatch, base excision, nucleotide excision, and double-strand DNA (dsDNA break repair. Concurrent with regulation of the cell cycle, these mechanisms are precisely executed to ensure full restoration of damaged DNA. Failure or inaccuracy in DNA repair contributes to genome instability and loss of genetic information which may lead to mutations resulting in disease or loss of life. A detailed understanding of the mechanisms of DNA damage and its repair provides insight into disease pathogeneses and may facilitate diagnosis and the development of targeted therapies.

  5. Bone and skeletal muscle: Key players in mechanotransduction and potential overlapping mechanisms.

    Science.gov (United States)

    Goodman, Craig A; Hornberger, Troy A; Robling, Alexander G

    2015-11-01

    The development and maintenance of skeletal muscle and bone mass is critical for movement, health and issues associated with the quality of life. Skeletal muscle and bone mass are regulated by a variety of factors that include changes in mechanical loading. Moreover, bone mass is, in large part, regulated by muscle-derived mechanical forces and thus by changes in muscle mass/strength. A thorough understanding of the cellular mechanism(s) responsible for mechanotransduction in bone and skeletal muscle is essential for the development of effective exercise and pharmaceutical strategies aimed at increasing, and/or preventing the loss of, mass in these tissues. Thus, in this review we will attempt to summarize the current evidence for the major molecular mechanisms involved in mechanotransduction in skeletal muscle and bone. By examining the differences and similarities in mechanotransduction between these two tissues, it is hoped that this review will stimulate new insights and ideas for future research and promote collaboration between bone and muscle biologists.(1). Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Motivation by potential gains and losses affects control processes via different mechanisms in the attentional network.

    Science.gov (United States)

    Paschke, Lena M; Walter, Henrik; Steimke, Rosa; Ludwig, Vera U; Gaschler, Robert; Schubert, Torsten; Stelzel, Christine

    2015-05-01

    Attentional control in demanding cognitive tasks can be improved by manipulating the motivational state. Motivation to obtain gains and motivation to avoid losses both usually result in faster reaction times and stronger activation in relevant brain areas such as the prefrontal cortex, but little is known about differences in the underlying neurocognitive mechanisms of these types of motivation in an attentional control context. In the present functional magnetic resonance imaging (fMRI) study, we tested whether potential gain and loss as motivating incentives lead to overlapping or distinct neural effects in the attentional network, and whether one of these conditions is more effective than the other. A Flanker task with word stimuli as targets and distracters was performed by 115 healthy participants. Using a mixed blocked and event-related design allowed us to investigate transient and sustained motivation-related effects. Participants could either gain money (potential gain) or avoid losing money (potential loss) in different task blocks. Participants showed a congruency effect with increased reaction times for incongruent compared to congruent trials. Potential gain led to generally faster responses compared to the neutral condition and to stronger improvements than potential loss. Potential loss also led to shorter response times compared to the neutral condition, but participants improved mainly during incongruent and not during congruent trials. The event-related fMRI data revealed a main effect of congruency with increased activity in the left inferior frontal gyrus (IFG) and inferior frontal junction area (IFJ), the pre-supplementary motor area (pre-SMA), bilateral insula, intraparietal sulcus (IPS) and visual word form area (VWFA). While potential gain led to increased activity in a cluster of the IFJ and the VWFA only during incongruent trials, potential loss was linked to activity increases in these regions during incongruent and congruent trials. The

  7. Potential Mechanisms for IgG4 Inhibition of Immediate Hypersensitivity Reactions.

    Science.gov (United States)

    James, Louisa K; Till, Stephen J

    2016-03-01

    IgG4 is the least abundant IgG subclass in human serum, representing less than 5% of all IgG. Increases in IgG4 occur following chronic exposure to antigen and are generally associated with states of immune tolerance. In line with this, IgG4 is regarded as an anti-inflammatory antibody with a limited ability to elicit effective immune responses. Furthermore, IgG4 attenuates allergic responses by inhibiting the activity of IgE. The mechanism by which IgG4 inhibits IgE-mediated hypersensitivity has been investigated using a variety of model systems leading to two proposed mechanisms. First by sequestering antigen, IgG4 can function as a blocking antibody, preventing cross-linking of receptor bound IgE. Second IgG4 has been proposed to co-stimulate the inhibitory IgG receptor FcγRIIb, which can negatively regulate FcεRI signaling and in turn inhibit effector cell activation. Recent advances in our understanding of the structural features of human IgG4 have shed light on the unique functional and immunologic properties of IgG4. The aim of this review is to evaluate our current understanding of IgG4 biology and reassess the mechanisms by which IgG4 functions to inhibit IgE-mediated allergic responses.

  8. Music and Memory in Alzheimer's Disease and The Potential Underlying Mechanisms.

    Science.gov (United States)

    Peck, Katlyn J; Girard, Todd A; Russo, Frank A; Fiocco, Alexandra J

    2016-01-01

    With population aging and a projected exponential expansion of persons diagnosed with Alzheimer's disease (AD), the development of treatment and prevention programs has become a fervent area of research and discovery. A growing body of evidence suggests that music exposure can enhance memory and emotional function in persons with AD. However, there is a paucity of research that aims to identify specific underlying neural mechanisms associated with music's beneficial effects in this particular population. As such, this paper reviews existing anecdotal and empirical evidence related to the enhancing effects of music exposure on cognitive function and further provides a discussion on the potential underlying mechanisms that may explain music's beneficial effect. Specifically, this paper will outline the potential role of the dopaminergic system, the autonomic nervous system, and the default network in explaining how music may enhance memory function in persons with AD.

  9. Idiosyncratic Drug-Induced Liver Injury (IDILI: Potential Mechanisms and Predictive Assays

    Directory of Open Access Journals (Sweden)

    Alexander D. Roth

    2017-01-01

    Full Text Available Idiosyncratic drug-induced liver injury (IDILI is a significant source of drug recall and acute liver failure (ALF in the United States. While current drug development processes emphasize general toxicity and drug metabolizing enzyme- (DME- mediated toxicity, it has been challenging to develop comprehensive models for assessing complete idiosyncratic potential. In this review, we describe the enzymes and proteins that contain polymorphisms believed to contribute to IDILI, including ones that affect phase I and phase II metabolism, antioxidant enzymes, drug transporters, inflammation, and human leukocyte antigen (HLA. We then describe the various assays that have been developed to detect individual reactions focusing on each of the mechanisms described in the background. Finally, we examine current trends in developing comprehensive models for examining these mechanisms. There is an urgent need to develop a panel of multiparametric assays for diagnosing individual toxicity potential.

  10. Cellular and Molecular Mechanisms of Diabetic Atherosclerosis: Herbal Medicines as a Potential Therapeutic Approach

    Directory of Open Access Journals (Sweden)

    Jinfan Tian

    2017-01-01

    Full Text Available An increasing number of patients diagnosed with diabetes mellitus eventually develop severe coronary atherosclerosis disease. Both type 1 and type 2 diabetes mellitus increase the risk of cardiovascular disease associated with atherosclerosis. The cellular and molecular mechanisms affecting the incidence of diabetic atherosclerosis are still unclear, as are appropriate strategies for the prevention and treatment of diabetic atherosclerosis. In this review, we discuss progress in the study of herbs as potential therapeutic agents for diabetic atherosclerosis.

  11. [Emissions trading potential : a mechanism to meet sustainability requirements for developing countries

    International Nuclear Information System (INIS)

    Govendor, V.

    1998-01-01

    The objectives of the Clean Development Mechanism (CDM) (sustainable development, adaptation to negative impacts, achieving compliance by developed nations, emission reduction against a defined baseline), and potential mechanisms for managing the CDM were described. In effect, the CDM is a means to ensure cost efficient greenhouse gas emissions reductions. It is also a tool to promote sustainable development in developing countries. As for managing CDM, the mechanism must include equitable regional representation, and balanced representation between developed and developing nations. It was emphasized that the mandate must be clear and unambiguous, and should include clarification of eligible projects, liaison between agencies and COP/MOP, managing the adaptation fund, oversee allocations to adaptation projects, and audit 'certified emission reduction' (CER) certified by CDM agencies. CERs should be based on solid technical definition and should be carefully verified, and joint implementation (JI) and emission trading should be measured and assessed against common criteria

  12. Promoting adaptive flood risk management: the role and potential of flood recovery mechanisms

    Directory of Open Access Journals (Sweden)

    Priest Sally J

    2016-01-01

    Full Text Available There is a high potential for recovery mechanisms to be used to incentivise the uptake of flood mitigation and loss reduction measures, undertake adaptation and promote community resilience. Indeed, creating a resilient response to flooding requires flood risk management approaches to be aligned and it needs to be ensured that recovery mechanisms to not provide disincentives for individuals and business to take proactive action to reduce risk. However, the degree to which it is desirable and effective for insurers and governments providing compensation to promote resilience and risk reduction depends upon how the cover or compensation is organised and the premiums which are charged. A review of international flood recovery mechanisms has been undertaken to identify firstly the types of schemes that exist and their characteristics. Analysis of existing instruments highlights that there are various potential approaches to encourage or require the uptake of flood mitigation and also discourage the construction of new development in high flood risk. However despite the presence of these instruments, those organising recovery mechanisms could be doing much more to incentivise increased resilience.

  13. Cadmium transfer and detoxification mechanisms in a soil-mulberry-silkworm system: phytoremediation potential.

    Science.gov (United States)

    Zhou, Lingyun; Zhao, Ye; Wang, Shuifeng

    2015-11-01

    Phytoremediation has been proven to be an environmentally sound alternative for the recovery of contaminated soils, and the economic profit that comes along with the process might stimulate its field use. This study investigated cadmium (Cd) transfer and detoxification mechanisms in a soil-mulberry-silkworm system to estimate the suitability of the mulberry and silkworm as an alternative method for the remediation of Cd-polluted soil; it also explored the underlying mechanisms regulating the trophic transfer of Cd. The results show that both the mulberry and silkworm have high Cd tolerance. The transfer factor suggests that the mulberry has high potential for Cd extraction from polluted soil. The subcellular distribution and chemical forms of Cd in mulberry leaves show that cell wall deposition and vacuolar compartmentalization play important role in Cd tolerance. In the presence of increasing Cd concentrations in silkworm food, detoxification mechanisms (excretion and homeostasis) were activated so that excess Cd was excreted in fecal balls, and metallothionein levels in the mid-gut, the posterior of the silk gland, and the fat body of silkworms were enhanced. And, the Cd concentrations in silk are at a low level, ranging from 0.02 to 0.21 mg kg(-1). Therefore, these mechanisms of detoxification can regulate Cd trophic transfer, and mulberry planting and silkworm breeding has high phytoremediation potential for Cd-contaminated soil.

  14. The Problems of Realizing the Innovative Potential of Science and Mechanisms for their Solution

    Directory of Open Access Journals (Sweden)

    Ianchenko Zinayida B.

    2017-06-01

    Full Text Available The aim of the article is revealing reasons for the low payoff of science in terms of the effectiveness of the research activity and demand for its results in economic spheres, identifying problems in the innovation activity of research institutions and reasons for their arising, searching for fundamental approaches to the development of a strategy and mechanisms for realization of the innovative potential of science to strengthen its position in the real sector. The study used general scientific methods, including: systems approach — to systematize the problems of the innovation activity of research institutions; methods of theoretical generalization — to study the theoretical principles of the scientific and innovation activity; methods of analysis and synthesis — to search for fundamental approaches to the development of mechanisms for realization of the innovative potential of science. The used concepts of scientific activity and innovations are generalized. The author’s definition of the term “innovation” is proposed. The main reasons of the minor impact of science on the economy are systematized, the mechanisms for their elimination are offered. Based on the comprehensive analysis of the reasons for losing by science its impact on the economy, the ways of realizing the innovative potential of science are improved. The results of the research can be used in reforming domestic scientific research institutions.

  15. Reproductive endocrine-disrupting effects of triclosan: Population exposure, present evidence and potential mechanisms

    International Nuclear Information System (INIS)

    Wang, Cai-Feng; Tian, Ying

    2015-01-01

    Triclosan has been used as a broad-spectrum antibacterial agent for over 40 years worldwide. Increasing reports indicate frequent detection and broad exposure to triclosan in the natural environment and the human body. Current laboratory studies in various species provide strong evidence for its disrupting effects on the endocrine system, especially reproductive hormones. Multiple modes of action have been suggested, including disrupting hormone metabolism, displacing hormones from hormone receptors and disrupting steroidogenic enzyme activity. Although epidemiological studies on its effects in humans are mostly negative but conflicting, which is typical of much of the early evidence on the toxicity of EDCs, overall, the evidence suggests that triclosan is an EDC. This article reviews human exposure to triclosan, describes the current evidence regarding its reproductive endocrine-disrupting effects, and discusses potential mechanisms to provide insights for further study on its endocrine-disrupting effects in humans. - Highlights: • Triclosan is widely detected in human urine, blood and breast milk. • Laboratory studies suggest reproductive endocrine-disrupting effects of triclosan. • Laboratory studies suggest estrogenic properties of triclosan. • There are three potential mechanisms regarding the estrogenic effect of triclosan. • Prospective epidemiological studies on vulnerable populations are needed. - This review summarizes current evidence on human exposure to triclosan, and its reproductive endocrine-disrupting effects and potential mechanisms.

  16. Resources, attitudes and culture: an understanding of the factors that influence the functioning of accountability mechanisms in primary health care settings.

    Science.gov (United States)

    Cleary, Susan M; Molyneux, Sassy; Gilson, Lucy

    2013-08-16

    District level health system governance is recognised as an important but challenging element of health system development in low and middle-income countries. Accountability is a more recent focus in health system debates. Accountability mechanisms are governance tools that seek to regulate answerability between the health system and the community (external accountability) and/or between different levels of the health system (bureaucratic accountability). External accountability has attracted significant attention in recent years, but bureaucratic accountability mechanisms, and the interactions between the two forms of accountability, have been relatively neglected. This is an important gap given that webs of accountability relationships exist within every health system. There is a need to strike a balance between achieving accountability upwards within the health system (for example through information reporting arrangements) while at the same time allowing for the local level innovation that could improve quality of care and patient responsiveness. Using a descriptive literature review, this paper examines the factors that influence the functioning of accountability mechanisms and relationships within the district health system, and draws out the implications for responsiveness to patients and communities. We also seek to understand the practices that might strengthen accountability in ways that improve responsiveness--of the health system to citizens' needs and rights, and of providers to patients. The review highlights the ways in which bureaucratic accountability mechanisms often constrain the functioning of external accountability mechanisms. For example, meeting the expectations of relatively powerful managers further up the system may crowd out efforts to respond to citizens and patients. Organisational cultures characterized by supervision and management systems focused on compliance to centrally defined outputs and targets can constrain front line

  17. MECHANISMS IN ENDOCRINOLOGY: Diabetic cardiomyopathy: pathophysiology and potential metabolic interventions state of the art review.

    Science.gov (United States)

    Levelt, Eylem; Gulsin, Gaurav; Neubauer, Stefan; McCann, Gerry P

    2018-04-01

    Heart failure is a major cause of morbidity and mortality in type 2 diabetes. Type 2 diabetes contributes to the development of heart failure through a variety of mechanisms, including disease-specific myocardial structural, functional and metabolic changes. This review will focus on the contemporary contributions of state of the art non-invasive technologies to our understanding of diabetic cardiomyopathy, including data on cardiac disease phenotype, cardiac energy metabolism and energetic deficiency, ectopic and visceral adiposity, diabetic liver disease, metabolic modulation strategies and cardiovascular outcomes with new classes of glucose-lowering therapies. © 2018 The authors.

  18. Review of numerical methods for simulation of mechanical heart valves and the potential for blood clotting.

    Science.gov (United States)

    Zakaria, Mohamad Shukri; Ismail, Farzad; Tamagawa, Masaaki; Aziz, Ahmad Fazli Abdul; Wiriadidjaja, Surjatin; Basri, Adi Azrif; Ahmad, Kamarul Arifin

    2017-09-01

    Even though the mechanical heart valve (MHV) has been used routinely in clinical practice for over 60 years, the occurrence of serious complications such as blood clotting remains to be elucidated. This paper reviews the progress that has been made over the years in terms of numerical simulation method and the contribution of abnormal flow toward blood clotting from MHVs in the aortic position. It is believed that this review would likely be of interest to some readers in various disciplines, such as engineers, scientists, mathematicians and surgeons, to understand the phenomenon of blood clotting in MHVs through computational fluid dynamics.

  19. From observation to understanding: Approach to analysis of wear mechanisms, Case of RCCAs and CRDM latch arms

    International Nuclear Information System (INIS)

    Hertz, D.

    2004-01-01

    Component wear can affect the ability of a component to fulfill its required function. For a designer or user, it is reasonable to expect possible wear occurrence as soon as parts are in relative motion. It is less obvious to extend this possibility to motions with small or very small amplitudes and loads. However, it has to be admitted that such cases exist. It then becomes imperative to determine the wear mechanisms so that the lifetime of the components and the optimum date of their replacement can be predicted or the degradation can be remedied. For this purpose, standard and widely accepted practice is to carry out simulator tests. Through examples of wear from nuclear reactor components such as the RCCAs (Rod Cluster Control Assembly) and the CRDM (Control Rod Drive Mechanism) latch arms, an approach for understanding the wear mechanisms and controlling their effects can be undertaken. Cases of wear have been observed on real-life parts, but the first simulator tests have shown deviations from in-reactor behaviour. Comparative examination of the wear facies of actual parts which have operated in reactor or simulators, both control rods and CRDM latch arms, was the key starting point for a new analytical approach, incorporating the formulation of wear mechanism hypotheses which can account for the observed facies. Expert assessment thus highlighted the importance of the environment by revealing that the wear featured a large component linked to friction-assisted corrosion. By including this tribo-corrosion aspect, it became possible to reach understanding of the mechanisms and account for the wear observed in reactor and on simulators. Further well-controlled simulator tests then made it possible to verify the importance of the tribo-corrosion processes in a pressurized water medium. Analysis of the physical chemical behaviour of the original materials (austenitic stainless steel) also explains why these surface modifications limit or remedy wear

  20. Systematic Understanding of Mechanisms of a Chinese Herbal Formula in Treatment of Metabolic Syndrome by an Integrated Pharmacology Approach.

    Science.gov (United States)

    Chen, Meimei; Yang, Fafu; Yang, Xuemei; Lai, Xinmei; Gao, Yuxing

    2016-12-16

    Metabolic syndrome (MS) is becoming a worldwide health problem. Wendan decoction (WDD)-a famous traditional Chinese medicine formula-has been extensively employed to relieve syndromes related to MS in clinical practice in China. However, its pharmacological mechanisms still remain vague. In this study, a comprehensive approach that integrated chemomics, principal component analysis, molecular docking simulation, and network analysis was established to elucidate the multi-component and multi-target mechanism of action of WDD in treatment of MS. The compounds in WDD were found to possess chemical diversity, complexity and drug-likeness compared to MS drugs. Six nuclear receptors were obtained to have strong binding affinity with 217 compounds of five herbs in WDD. The importance roles of targets and herbs were also identified due to network parameters. Five compounds from Radix Glycyrrhizae Preparata can hit all six targets, which can assist in screening new MS drugs. The pathway network analysis demonstrated that the main pharmacological effects of WDD might lie in maintaining lipid and glucose metabolisms and anticancer activities as well as immunomodulatory and hepatoprotective effects. This study provided a comprehensive system approach for understanding the multi-component, multi-target and multi-pathway mechanisms of WDD during the treatment of MS.

  1. Systematic Understanding of Mechanisms of a Chinese Herbal Formula in Treatment of Metabolic Syndrome by an Integrated Pharmacology Approach

    Directory of Open Access Journals (Sweden)

    Meimei Chen

    2016-12-01

    Full Text Available Metabolic syndrome (MS is becoming a worldwide health problem. Wendan decoction (WDD—a famous traditional Chinese medicine formula—has been extensively employed to relieve syndromes related to MS in clinical practice in China. However, its pharmacological mechanisms still remain vague. In this study, a comprehensive approach that integrated chemomics, principal component analysis, molecular docking simulation, and network analysis was established to elucidate the multi-component and multi-target mechanism of action of WDD in treatment of MS. The compounds in WDD were found to possess chemical diversity, complexity and drug-likeness compared to MS drugs. Six nuclear receptors were obtained to have strong binding affinity with 217 compounds of five herbs in WDD. The importance roles of targets and herbs were also identified due to network parameters. Five compounds from Radix Glycyrrhizae Preparata can hit all six targets, which can assist in screening new MS drugs. The pathway network analysis demonstrated that the main pharmacological effects of WDD might lie in maintaining lipid and glucose metabolisms and anticancer activities as well as immunomodulatory and hepatoprotective effects. This study provided a comprehensive system approach for understanding the multi-component, multi-target and multi-pathway mechanisms of WDD during the treatment of MS.

  2. Understanding the mechanical properties of DNA origami tiles and controlling the kinetics of their folding and unfolding reconfiguration.

    Science.gov (United States)

    Chen, Haorong; Weng, Te-Wei; Riccitelli, Molly M; Cui, Yi; Irudayaraj, Joseph; Choi, Jong Hyun

    2014-05-14

    DNA origami represents a class of highly programmable macromolecules that can go through conformational changes in response to external signals. Here we show that a two-dimensional origami rectangle can be effectively folded into a short, cylindrical tube by connecting the two opposite edges through the hybridization of linker strands and that this process can be efficiently reversed via toehold-mediated strand displacement. The reconfiguration kinetics was experimentally studied as a function of incubation temperature, initial origami concentration, missing staples, and origami geometry. A kinetic model was developed by introducing the j factor to describe the reaction rates in the cyclization process. We found that the cyclization efficiency (j factor) increases sharply with temperature and depends strongly on the structural flexibility and geometry. A simple mechanical model was used to correlate the observed cyclization efficiency with origami structure details. The mechanical analysis suggests two sources of the energy barrier for DNA origami folding: overcoming global twisting and bending the structure into a circular conformation. It also provides the first semiquantitative estimation of the rigidity of DNA interhelix crossovers, an essential element in structural DNA nanotechnology. This work demonstrates efficient DNA origami reconfiguration, advances our understanding of the dynamics and mechanical properties of self-assembled DNA structures, and should be valuable to the field of DNA nanotechnology.

  3. Deciphering spreading mechanisms in amyotrophic lateral sclerosis: clinical evidence and potential molecular processes.

    Science.gov (United States)

    Pradat, Pierre-François; Kabashi, Edor; Desnuelle, Claude

    2015-10-01

    The aim of this review is to refer to recent arguments supporting the existence of specific propagation mechanisms associated with spreading of neuron injury in amyotrophic lateral sclerosis (ALS). Misfolded ALS-linked protein accumulation can induce aggregation of their native equivalent isoforms through a mechanism analogous to the infectious prion proteins initiation and its propagation. Although ALS is clinically heterogeneous, a shared characteristic is the focal onset and the progressive extension to all body regions. Being viewed until now as just summation of the increased number of affected neurons, dispersion is now rather considered as the result of a seeded self-propagating process. A sequential regional spreading pattern is supported by the distribution of TDP-43 aggregates in ALS autopsy cases. Electrophysiology and advanced neuroimaging methods also recently provided some evidence for propagation of lesions both in the brain and spinal cord, more longitudinal studies being still needed. Lesions are supposed to spread cell-to-cell regionally or through connected neuronal pathway. At the molecular level, the prion-like spreading is an emerging mechanism hypothesis, but other machineries such as those that are in charge of dealing with misfolded proteins and secretion of deleterious peptides may be involved in the propagation of neuron loss. Deciphering the mechanisms underlying spreading of ALS symptoms is of crucial importance to better understand this neurodegenerative disease, build new and appropriate animal models and to define novel therapeutic targets.

  4. Chemical compounds from anthropogenic environment and immune evasion mechanisms: potential interactions

    Science.gov (United States)

    Kravchenko, Julia; Corsini, Emanuela; Williams, Marc A.; Decker, William; Manjili, Masoud H.; Otsuki, Takemi; Singh, Neetu; Al-Mulla, Faha; Al-Temaimi, Rabeah; Amedei, Amedeo; Colacci, Anna Maria; Vaccari, Monica; Mondello, Chiara; Scovassi, A. Ivana; Raju, Jayadev; Hamid, Roslida A.; Memeo, Lorenzo; Forte, Stefano; Roy, Rabindra; Woodrick, Jordan; Salem, Hosni K.; Ryan, Elizabeth P.; Brown, Dustin G.; Lowe, Leroy; Lyerly, H.Kim

    2015-01-01

    An increasing number of studies suggest an important role of host immunity as a barrier to tumor formation and progression. Complex mechanisms and multiple pathways are involved in evading innate and adaptive immune responses, with a broad spectrum of chemicals displaying the potential to adversely influence immunosurveillance. The evaluation of the cumulative effects of low-dose exposures from the occupational and natural environment, especially if multiple chemicals target the same gene(s) or pathway(s), is a challenge. We reviewed common environmental chemicals and discussed their potential effects on immunosurveillance. Our overarching objective was to review related signaling pathways influencing immune surveillance such as the pathways involving PI3K/Akt, chemokines, TGF-β, FAK, IGF-1, HIF-1α, IL-6, IL-1α, CTLA-4 and PD-1/PDL-1 could individually or collectively impact immunosurveillance. A number of chemicals that are common in the anthropogenic environment such as fungicides (maneb, fluoxastrobin and pyroclostrobin), herbicides (atrazine), insecticides (pyridaben and azamethiphos), the components of personal care products (triclosan and bisphenol A) and diethylhexylphthalate with pathways critical to tumor immunosurveillance. At this time, these chemicals are not recognized as human carcinogens; however, it is known that they these chemicalscan simultaneously persist in the environment and appear to have some potential interfere with the host immune response, therefore potentially contributing to promotion interacting with of immune evasion mechanisms, and promoting subsequent tumor growth and progression. PMID:26002081

  5. Perchlorate formation on Mars through surface radiolysis-initiated atmospheric chemistry: A potential mechanism

    Science.gov (United States)

    Wilson, Eric H.; Atreya, Sushil K.; Kaiser, Ralf I.; Mahaffy, Paul R.

    2016-08-01

    Recent observations of the Martian surface by the Phoenix lander and the Sample Analysis at Mars indicate the presence of perchlorate (ClO4-). The abundance and isotopic composition of these perchlorates suggest that the mechanisms responsible for their formation in the Martian environment may be unique in our solar system. With this in mind, we propose a potential mechanism for the production of Martian perchlorate: the radiolysis of the Martian surface by galactic cosmic rays, followed by the sublimation of chlorine oxides into the atmosphere and their subsequent synthesis to form perchloric acid (HClO4) in the atmosphere, and the surface deposition and subsequent mineralization of HClO4 in the regolith to form surface perchlorates. To evaluate the viability of this mechanism, we employ a one-dimensional chemical model, examining chlorine chemistry in the context of Martian atmospheric chemistry. Considering the chlorine oxide, OClO, we find that an OClO flux as low as 3.2 × 107 molecules cm-2 s-1 sublimated into the atmosphere from the surface could produce sufficient HClO4 to explain the perchlorate concentration on Mars, assuming an accumulation depth of 30 cm and integrated over the Amazonian period. Radiolysis provides an efficient pathway for the oxidation of chlorine, bypassing the efficient Cl/HCl recycling mechanism that characterizes HClO4 formation mechanisms proposed for the Earth but not Mars.

  6. Cannabinoid hyperemesis syndrome: potential mechanisms for the benefit of capsaicin and hot water hydrotherapy in treatment.

    Science.gov (United States)

    Richards, John R; Lapoint, Jeff M; Burillo-Putze, Guillermo

    2018-01-01

    Cannabinoid hyperemesis syndrome is a clinical disorder that has become more prevalent with increasing use of cannabis and synthetic cannabinoids, and which is difficult to treat. Standard antiemetics commonly fail to alleviate the severe nausea and vomiting characteristic of the syndrome. Curiously, cannabinoid hyperemesis syndrome patients often report dramatic relief of symptoms with hot showers and baths, and topical capsaicin. In this review, we detail the pharmacokinetics and pharmacodynamics of capsaicin and explore possible mechanisms for its beneficial effect, including activation of transient receptor potential vanilloid 1 and neurohumoral regulation. Putative mechanisms responsible for the benefit of hot water hydrotherapy are also investigated. An extensive search of PubMed, OpenGrey, and Google Scholar from inception to April 2017 was performed to identify known and theoretical thermoregulatory mechanisms associated with the endocannabinoid system. The searches resulted in 2417 articles. These articles were screened for relevant mechanisms behind capsaicin and heat activation having potential antiemetic effects. References from the selected articles were also hand-searched. A total of 137 articles were considered relevant and included. Capsaicin: Topical capsaicin is primarily used for treatment of neuropathic pain, but it has also been used successfully in some 20 cases of cannabinoid hyperemesis syndrome. The pharmacokinetics and pharmacodynamics of capsaicin as a transient receptor potential vanilloid 1 agonist may explain this effect. Topical capsaicin has a longer half-life than oral administration, thus its potential duration of benefit is longer. Capsaicin and transient receptor potential vanilloid 1: Topical capsaicin binds and activates the transient receptor potential vanilloid 1 receptor, triggering influx of calcium and sodium, as well as release of inflammatory neuropeptides leading to transient burning, stinging, and itching. This elicits

  7. Potential Molecular Mechanisms on the Role of the Sigma-1 Receptor in the Action of Cocaine and Methamphetamine

    Science.gov (United States)

    Yasui, Yuko; Su, Tsung-Ping

    2016-01-01

    The sigma-1 receptor (Sig-1R) is an endoplasmic reticulum membrane protein that involves a wide range of physiological functions. The Sig-1R has been shown to bind psychostimulants including cocaine and methamphetamine (METH) and thus has been implicated in the actions of those psychostimulants. For example, it has been demonstrated that the Sig-1R antagonists mitigate certain behavioral and cellular effects of psychostimulants including hyperactivity and neurotoxicity. Thus, the Sig-1R has become a potential therapeutic target of medication development against drug abuse that differs from traditional monoamine-related strategies. In this review, we will focus on the molecular mechanisms of the Sig-1R and discuss in such a manner with a hope to further understand or unveil unexplored relations between the Sig-1R and the actions of cocaine and METH, particularly in the context of cellular biological relevance. PMID:27088037

  8. Identification of up-regulated proteins potentially involved in the antagonism mechanism of Bacillus amyloliquefaciens G1.

    Science.gov (United States)

    Cao, Haipeng; Zheng, Weidong; He, Shan; Wang, Hao; Wang, Tu; Lu, Liqun

    2013-06-01

    The use of Bacillus probiotics has been demonstrated as a promising method in the biocontrol of bacterial diseases in aquaculture. However, the molecular antibacterial mechanism of Bacillus still remains unclear. In order to explore the antibacterial mechanism of the potential antagonistic Bacillus amyloliquefaciens strain G1, comparative proteomics between B. amyloliquefaciens strain G1 and its non-antagonistic mutant strain was investigated. The 2-dimensional electrophoresis gel maps of their total extracted proteins were described and 42 different proteins were found to be highly expressed in strain G1 in comparison with those in the mutant strain. 35 of these up-regulated proteins were successfully identified using MALDI-TOF-TOF MS and databank analysis, and their biological functions were analyzed through the KEGG database. The increased expression of these proteins suggested that high levels of energy metabolism, biosynthesis and stress resistance could play important roles in strain G1's antagonism. To our knowledge, this is the first report on the proteins involved in the antagonism mechanism of B. amyloliquefaciens using a proteomic approach and the proteomic data also contribute to a better understanding of the molecular basis for the antagonism of B. amyloliquefaciens.

  9. Applying GRADE-CERQual to qualitative evidence synthesis findings-paper 7: understanding the potential impacts of dissemination bias.

    Science.gov (United States)

    Booth, Andrew; Lewin, Simon; Glenton, Claire; Munthe-Kaas, Heather; Toews, Ingrid; Noyes, Jane; Rashidian, Arash; Berg, Rigmor C; Nyakang'o, Brenda; Meerpohl, Joerg J

    2018-01-25

    The GRADE-CERQual (Confidence in Evidence from Reviews of Qualitative research) approach has been developed by the GRADE (Grading of Recommendations Assessment, Development and Evaluation) Working Group. The approach has been developed to support the use of findings from qualitative evidence syntheses in decision-making, including guideline development and policy formulation. CERQual includes four components for assessing how much confidence to place in findings from reviews of qualitative research (also referred to as qualitative evidence syntheses): (1) methodological limitations, (2) coherence, (3) adequacy of data and (4) relevance. This paper is part of a series providing guidance on how to apply CERQual and focuses on a probable fifth component, dissemination bias. Given its exploratory nature, we are not yet able to provide guidance on applying this potential component of the CERQual approach. Instead, we focus on how dissemination bias might be conceptualised in the context of qualitative research and the potential impact dissemination bias might have on an overall assessment of confidence in a review finding. We also set out a proposed research agenda in this area. We developed this paper by gathering feedback from relevant research communities, searching MEDLINE and Web of Science to identify and characterise the existing literature discussing or assessing dissemination bias in qualitative research and its wider implications, developing consensus through project group meetings, and conducting an online survey of the extent, awareness and perceptions of dissemination bias in qualitative research. We have defined dissemination bias in qualitative research as a systematic distortion of the phenomenon of interest due to selective dissemination of studies or individual study findings. Dissemination bias is important for qualitative evidence syntheses as the selective dissemination of qualitative studies and/or study findings may distort our understanding of

  10. Hijama therapy (wet cupping) - its potential use to complement British healthcare in practice, understanding, evidence and regulation.

    Science.gov (United States)

    Sajid, Mohammed Imran

    2016-05-01

    Wet cupping was used in the nineteenth century for treatment of patients in the United Kingdom (UK) by a few experienced practitioners. Revival Hijama use by practitioners in the UK in recent years has been observed as well as interest from the public, with developments of specific certified training programmes, established businesses providing tailored Hijama therapy Clinical Waste disposal services, provisions of insurance cover, involvement of medical professionals and membership with the General Regulatory Council for Complementary Therapies (GRCCT). However, there has also been noted that there is not much in the way of guidance or regulation. Therefore, we would like to initiate some communication and understanding of Hijama (wet cupping) to benefit medical professionals, discussing recent research undertaken as a basis for potentially more in the future (evidence-based practice), in the likely event that a patient might request to be referred for this therapy during a consultation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Determination of LFER descriptors of 30 cations of ionic liquids--progress in understanding their molecular interaction potentials.

    Science.gov (United States)

    Cho, Chul-Woong; Jungnickel, Christian; Stolte, Stefan; Preiss, Ulrich; Arning, Jürgen; Ranke, Johannes; Krossing, Ingo; Thöming, Jorg

    2012-02-01

    In order to understand molecular interaction potentials of 30 cations of ionic liquids (ILs), the well-known linear free energy relationship concept (LFER) was applied. The LFER descriptors for the excess molar refractivity and the molar volume were calculated in silico and for hydrogen-bonding acidity and basicity, and the polarizability/dipolarity of IL cations were experimentally determined through high performance liquid chromatography (HPLC) measurements. For the study, three different columns (RP-select B, Cyan, and Diol) and buffered mobile phases, based on two organic solvents acetonitrile (ACN) and methanol (MeOH), were selectively combined to the HPLC separation systems RP-select B-ACN, RP-select B-MeOH, Cyan-MeOH, Diol-ACN, and Diol-MeOH. By measuring the retention factors of 45 neutral calibration compounds and calculating LFER descriptors of three cations in the HPLC systems, the system parameters, including an ionic z coefficient, were determined. Conversely, the LFER descriptors of 30 ionic liquid cations were determined, based on the parameters of five systems and their retention factors in the HPLC systems. The results showed that the type of head group, alkyl chain length and further substituents of the cation have a significant influence on the dipolarity/polarizability and the hydrogen-bonding acidity, and functionalized groups (hydroxyl, ether, and dimethylamino) lead to hydrogen-bonding basicity of the cation. The characterization of cationic LFER descriptors opens up the chance for a more quantitative understanding of molecular interaction potentials and physicochemical properties of ILs. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Recent progress in the understanding of tissue culture-induced genome level changes in plants and potential applications.

    Science.gov (United States)

    Neelakandan, Anjanasree K; Wang, Kan

    2012-04-01

    In vitro cell and tissue-based systems have tremendous potential in fundamental research and for commercial applications such as clonal propagation, genetic engineering and production of valuable metabolites. Since the invention of plant cell and tissue culture techniques more than half a century ago, scientists have been trying to understand the morphological, physiological, biochemical and molecular changes associated with tissue culture responses. Establishment of de novo developmental cell fate in vitro is governed by factors such as genetic make-up, stress and plant growth regulators. In vitro culture is believed to destabilize the genetic and epigenetic program of intact plant tissue and can lead to chromosomal and DNA sequence variations, methylation changes, transposon activation, and generation of somaclonal variants. In this review, we discuss the current status of understanding the genomic and epigenomic changes that take place under in vitro conditions. It is hoped that a precise and comprehensive knowledge of the molecular basis of these variations and acquisition of developmental cell fate would help to devise strategies to improve the totipotency and embryogenic capability in recalcitrant species and genotypes, and to address bottlenecks associated with clonal propagation. © Springer-Verlag 2011

  13. Review of the current understanding of the potential for containment failure from in-vessel steam explosions

    International Nuclear Information System (INIS)

    1985-06-01

    A group of experts was convened to review the current understanding of the potential for containment failure from in-vessel steam explosions during core meltdown accidents in LWRs. The Steam Explosion Review Group (SERG) was requested to provide assessments of: (1) the conditional probability of containment failure due to a steam explosion, (2) a Sandia National Laboratory (SNL) report entitled ''An Uncertainty Study of PWR Steam Explosions,'' NUREG/CR-3369, (3) a SNL proposed steam explosion research program. This report summarizes the results of the deliberations of the review group. It also presents the detailed response of each individual member to each of the issues. The consensus of the SERG is that the occurrence of a steam explosion of sufficient energetics which could lead to alpha-mode containment failure has a low probability. The SERG members disagreed with the methodology used in NUREG/CR-3369 for the purpose of establishing the uncertainty in the probability of containment failure by a steam explosion. A consensus was reached among SERG members on the need for a continuing steam explosion research program which would improve our understanding of certain aspects of steam explosion phenomenology

  14. Kidney disease models: tools to identify mechanisms and potential therapeutic targets

    Science.gov (United States)

    Bao, Yin-Wu; Yuan, Yuan; Chen, Jiang-Hua; Lin, Wei-Qiang

    2018-01-01

    Acute kidney injury (AKI) and chronic kidney disease (CKD) are worldwide public health problems affecting millions of people and have rapidly increased in prevalence in recent years. Due to the multiple causes of renal failure, many animal models have been developed to advance our understanding of human nephropathy. Among these experimental models, rodents have been extensively used to enable mechanistic understanding of kidney disease induction and progression, as well as to identify potential targets for therapy. In this review, we discuss AKI models induced by surgical operation and drugs or toxins, as well as a variety of CKD models (mainly genetically modified mouse models). Results from recent and ongoing clinical trials and conceptual advances derived from animal models are also explored. PMID:29515089

  15. Multiple mechanisms involved in the large-spectrum therapeutic potential of cannabidiol in psychiatric disorders

    Science.gov (United States)

    Campos, Alline Cristina; Moreira, Fabricio Araújo; Gomes, Felipe Villela; Del Bel, Elaine Aparecida; Guimarães, Francisco Silveira

    2012-01-01

    Cannabidiol (CBD) is a major phytocannabinoid present in the Cannabis sativa plant. It lacks the psychotomimetic and other psychotropic effects that the main plant compound Δ9-tetrahydrocannabinol (THC) being able, on the contrary, to antagonize these effects. This property, together with its safety profile, was an initial stimulus for the investigation of CBD pharmacological properties. It is now clear that CBD has therapeutic potential over a wide range of non-psychiatric and psychiatric disorders such as anxiety, depression and psychosis. Although the pharmacological effects of CBD in different biological systems have been extensively investigated by in vitro studies, the mechanisms responsible for its therapeutic potential are still not clear. Here, we review recent in vivo studies indicating that these mechanisms are not unitary but rather depend on the behavioural response being measured. Acute anxiolytic and antidepressant-like effects seem to rely mainly on facilitation of 5-HT1A-mediated neurotransmission in key brain areas related to defensive responses, including the dorsal periaqueductal grey, bed nucleus of the stria terminalis and medial prefrontal cortex. Other effects, such as anti-compulsive, increased extinction and impaired reconsolidation of aversive memories, and facilitation of adult hippocampal neurogenesis could depend on potentiation of anandamide-mediated neurotransmission. Finally, activation of TRPV1 channels may help us to explain the antipsychotic effect and the bell-shaped dose-response curves commonly observed with CBD. Considering its safety profile and wide range of therapeutic potential, however, further studies are needed to investigate the involvement of other possible mechanisms (e.g. inhibition of adenosine uptake, inverse agonism at CB2 receptor, CB1 receptor antagonism, GPR55 antagonism, PPARγ receptors agonism, intracellular (Ca2+) increase, etc.), on CBD behavioural effects. PMID:23108553

  16. New Insights on plant salt tolerance mechanisms and their potential use for breeding

    Directory of Open Access Journals (Sweden)

    Moez HANIN

    2016-11-01

    Full Text Available Soil salinization is a major threat to agriculture in arid and semi-arid regions, where water scarcity and inadequate drainage of irrigated lands severely reduce crop yield. Salt accumulation inhibits plant growth and reduces the ability to uptake water and nutrients, leading to osmotic or water-deficit stress. Salt is also causing injury of the young photosynthetic leaves and acceleration of their senescence, as the Na+ cation is toxic when accumulating in cell cytosol resulting in ionic imbalance and toxicity of transpiring leaves. To cope with salt stress, plants have evolved mainly two types of tolerance mechanisms based on either limiting the entry of salt by the roots, or controlling its concentration and distribution. Understanding the overall control of Na+ accumulation and functional studies of genes involved in transport processes, will provide a new opportunity to improve the salinity tolerance of plants relevant to food security in arid regions. A better understanding of these tolerance mechanisms can be used to breed crops with improved yield performance under salinity stress. Moreover, associations of cultures with nitrogen-fixing bactéria and arbuscular mycorrhizal fungi could serve as an alternative and sustainable strategy to increase crop yields in salt affected fields.

  17. Ferrous archaeological analogues for the understanding of the multi-secular corrosion mechanisms in an anoxic environment

    International Nuclear Information System (INIS)

    Saheb-Djahromi, M.

    2009-12-01

    Understanding the long term corrosion mechanisms of iron in an anoxic environment is essential in the field of the radioactive waste storage. In France, it is planned to store high level nuclear wastes in a multi-barrier system containing a glassy matrix surrounded by a stainless steel container, embedded in a low-carbon steel over-container. This system would be placed in a deep geological repository, which would impose anoxic conditions. As it must be efficient for a period of several thousands of years, one should understand the alteration mechanisms that are expected to occur in such a long time. To this purpose, a specific approach is developed on ferrous archaeological analogues with thick corrosion layer formed in natural conditions. In this study, the corrosion mechanisms have been assessed by examining nails aged of 400 years coming from the archaeological site of Glinet, selected as a reference site. The first point was a fine characterisation of the entire corrosion system metal / corrosion products / medium, through the use of coupled multi-scale analytical tools. The first results showed that the samples were corroded in an anoxic calco-carbonated environment. Moreover, the coupling of X-ray micro-diffraction, Raman microspectroscopy and dispersive energy spectroscopy has enabled to identify three corrosion systems composed of iron carbonates, siderite and chukanovite, and magnetite. Depending on the phase's layout in the system, the electronic resistance of the corrosion layers has been established, from resistive to conductive. In a second stage, re-corroding experiments in laboratory were performed. Firstly, the electrochemical behaviour of the corrosion system has shown that water reduction at the metallic interface is negligible. Furthermore, reaction tracing with copper and deuterium has allowed identifying the electron consumptions sites mainly localised on the external part, and the precipitation sites on the internal part of the corrosion

  18. Understanding the mechanism of direct electrochemistry of mitochondria-modified electrodes from yeast, potato and bovine sources at carbon paper electrodes

    International Nuclear Information System (INIS)

    Giroud, Fabien; Nicolo, Tera A.; Koepke, Sara J.; Minteer, Shelley D.

    2013-01-01

    Although mitochondria have been used for bio-electrochemistry for over 5 years, little is known about their direct electrochemistry mechanism. This paper focuses on developing a better understanding of the electron transfer mechanism of mitochondria from three different organisms at carbon electrodes. Yeast, potato and bovine mitochondria have been successfully isolated and immobilized onto Toray paper electrodes via vapor deposited silica. Organelle-modified electrodes were first characterized using cyclic voltammetry. Similar electrochemical signals were obtained for all organisms. Direct electron transfer was observed when a metabolite of the Krebs cycle was present in the buffer solution. Control experiments based on the immobilization of two electron carriers contained in mitochondria, cytochrome c and a quinone (coenzyme Q 10 ), tend to show the electron transfer mechanism to the carbon material comes from the quinone pool of the organelles. As quinones are known to be pH-dependent, we further investigated the response of the electrochemical signal of the three isolated mitochondria and the two electron carriers separately. The half wave potentials obtained from the organelles appeared to be pH-dependent and their variations are comparable to coenzyme Q 10 rather than cytochrome c. Finally, extraction of both the cytochrome c and the quinone pool from intact mitochondria was performed to validate our hypothesis that direct electrochemistry of mitochondria happens via the quinone pool. Electrochemistry of immobilized quinone-depleted mitochondria validated the hypothesis that the mitochondria are communicating with the electrodes through the quinone pool

  19. Lifelong bilingualism and neural reserve against Alzheimer's disease: a review of findings and potential mechanisms.

    Science.gov (United States)

    Gold, Brian T

    2015-03-15

    Alzheimer's disease (AD) is a progressive brain disorder that initially affects medial temporal lobe circuitry and memory functions. Current drug treatments have only modest effects on the symptomatic course of the disease. In contrast, a growing body of evidence suggests that lifelong bilingualism may delay the onset of clinical AD symptoms by several years. The purpose of the present review is to summarize evidence for bilingualism as a reserve variable against AD and discuss potential underlying neurocognitive mechanisms. Evidence is reviewed suggesting that bilingualism may delay clinical AD symptoms by protecting frontostriatal and frontoparietal executive control circuitry rather than medial temporal lobe memory circuitry. Cellular and molecular mechanisms that may contribute to bilingual cognitive reserve effects are discussed, including those that may affect neuronal metabolic functions, dynamic neuronal-glial interactions, vascular factors, myelin structure and neurochemical signaling. Future studies that may test some of these potential mechanisms of bilingual CR effects are proposed. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Contributions of human tissue analysis to understanding the mechanisms of loosening and osteolysis in total hip replacement

    DEFF Research Database (Denmark)

    Gallo, Jiri; Vaculova, Jana; Goodman, Stuart B

    2014-01-01

    Aseptic loosening and osteolysis are the most frequent late complications of total hip arthroplasty (THA) leading to revision of the prosthesis. This review aims to demonstrate how histopathological studies contribute to our understanding of the mechanisms of aseptic loosening...... of pathophysiological events that lead to prosthetic loosening and osteolysis. One possible solution is to examine tissues harvested from stable total hip arthroplasties that have been revised at various time periods due to dislocation or periprosthetic fracture in multicenter studies....... molecules of the host response at the protein level (chemokines, cytokines, nitric oxide metabolites, metalloproteinases). However, these studies also have important limitations. Tissues harvested at revision surgery reflect specifically end-stage failure and may not adequately reveal the evolution...

  1. Toward understanding the anticorrosive mechanism of some thiourea derivatives for carbon steel corrosion: A combined DFT and molecular dynamics investigation.

    Science.gov (United States)

    Guo, Lei; Kaya, Savaş; Obot, Ime Bassey; Zheng, Xingwen; Qiang, Yujie

    2017-11-15

    The mutually corroborated density functional theory (DFT) and molecular dynamics (MD) simulation methodology were employed to evaluate the inhibition performance of three thiourea derivatives (Inh1, Inh2, and Inh3) on carbon steel corrosion. Experimental results have shown that the corrosion rate follows the order: Inh3>Inh2>Inh1. Quantum chemical descriptors such as the frontier orbital energies (E HOMO and E LUMO ), the energy gap between E LUMO and E HOMO (ΔE), dipole moment (μ), and Fukui index have been calculated and discussed. Some significant factors such as solvent, temperature, and coverage have been considered when investigating the adsorption of aforementioned thiourea derivatives on Fe(110) surface. Our results provide important atomic/molecular insights into the anticorrosive mechanism of inhibitor molecules, which could help in understanding the organic-metal interface and designing more appropriate organic corrosion inhibitors. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Impacts of prenatal triclosan exposure on fetal reproductive hormones and its potential mechanism.

    Science.gov (United States)

    Wang, Caifeng; Chen, Limei; Zhao, Shasha; Hu, Yi; Zhou, Yijun; Gao, Yu; Wang, Weiye; Zhang, Jun; Tian, Ying

    2018-02-01

    Triclosan (TCS) has been widely detected in pregnant women. The reproductive endocrine-disrupting effects of TCS have been observed in humans and animals. Little is known about the potential impact of prenatal TCS exposure on fetal reproductive development as well as its potential mechanism. We investigated the potential effect of prenatal TCS exposure on fetal reproductive hormones in cord blood and its potential mechanism in relation to placental steroidogenic enzymes. Urinary TCS was detected among 537 healthy pregnant women from a prospective cohort in China. Four reproductive hormones in cord blood, namely E 2 (n=430), T (n=424), LH (n=428) and FSH (n=373), and three steroidogenic enzymes in placenta, namely P450arom (n=233), 3β-HSD (n=227) and 17β-HSD (n=222), were measured. Prenatal TCS exposure was associated with increased testosterone concentrations in cord blood in a dose-dependent manner. Infants with prenatal TCS levels >0.6μg/L had, on average, a 0.23ng/mL (95% CI: 0.05, 0.45, p=0.02) higher testosterone concentrations in cord blood compared to those with prenatal TCS levels prenatal TCS exposure was associated with increased testosterone and decreased E 2 concentrations in cord blood among male infants. Adverse associations were found between the prenatal TCS exposure and concentrations of three placental steroidogenic enzymes. 3β-HSD and P450arom demonstrated mediating effects in the association between prenatal TCS exposure and testosterone concentrations in cord blood. Our findings suggested potential impacts of prenatal TCS exposure on reproductive hormones in cord blood mediated by steroidogenic enzymes, and male infants were more vulnerable. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Potential of wind power projects under the Clean Development Mechanism in India.

    Science.gov (United States)

    Purohit, Pallav; Michaelowa, Axel

    2007-07-30

    So far, the cumulative installed capacity of wind power projects in India is far below their gross potential (tax benefits, long term financing schemes etc., for more than 10 years etc. One of the major barriers is the high costs of investments in these systems. The Clean Development Mechanism (CDM) of the Kyoto Protocol provides industrialized countries with an incentive to invest in emission reduction projects in developing countries to achieve a reduction in CO2 emissions at lowest cost that also promotes sustainable development in the host country. Wind power projects could be of interest under the CDM because they directly displace greenhouse gas emissions while contributing to sustainable rural development, if developed correctly. Our estimates indicate that there is a vast theoretical potential of CO2 mitigation by the use of wind energy in India. The annual potential Certified Emissions Reductions (CERs) of wind power projects in India could theoretically reach 86 million. Under more realistic assumptions about diffusion of wind power projects based on past experiences with the government-run programmes, annual CER volumes by 2012 could reach 41 to 67 million and 78 to 83 million by 2020. The projections based on the past diffusion trend indicate that in India, even with highly favorable assumptions, the dissemination of wind power projects is not likely to reach its maximum estimated potential in another 15 years. CDM could help to achieve the maximum utilization potential more rapidly as compared to the current diffusion trend if supportive policies are introduced.

  4. Supersymmetric quantum mechanics: Engineered hierarchies of integrable potentials and related orthogonal polynomials

    Energy Technology Data Exchange (ETDEWEB)

    Balondo Iyela, Daddy [International Chair in Mathematical Physics and Applications (ICMPA–UNESCO Chair), University of Abomey–Calavi, 072 B. P. 50 Cotonou, Republic of Benin (Benin); Centre for Cosmology, Particle Physics and Phenomenology (CP3), Institut de Recherche en Mathématique et Physique (IRMP), Université catholique de Louvain U.C.L., 2, Chemin du Cyclotron, B-1348 Louvain-la-Neuve (Belgium); Département de Physique, Université de Kinshasa (UNIKIN), B.P. 190 Kinshasa XI, Democratic Republic of Congo (Congo, The Democratic Republic of the); Govaerts, Jan [International Chair in Mathematical Physics and Applications (ICMPA–UNESCO Chair), University of Abomey–Calavi, 072 B. P. 50 Cotonou, Republic of Benin (Benin); Centre for Cosmology, Particle Physics and Phenomenology (CP3), Institut de Recherche en Mathématique et Physique (IRMP), Université catholique de Louvain U.C.L., 2, Chemin du Cyclotron, B-1348 Louvain-la-Neuve (Belgium); Hounkonnou, M. Norbert [International Chair in Mathematical Physics and Applications (ICMPA–UNESCO Chair), University of Abomey–Calavi, 072 B. P. 50 Cotonou, Republic of Benin (Benin)

    2013-09-15

    Within the context of supersymmetric quantum mechanics and its related hierarchies of integrable quantum Hamiltonians and potentials, a general programme is outlined and applied to its first two simplest illustrations. Going beyond the usual restriction of shape invariance for intertwined potentials, it is suggested to require a similar relation for Hamiltonians in the hierarchy separated by an arbitrary number of levels, N. By requiring further that these two Hamiltonians be in fact identical up to an overall shift in energy, a periodic structure is installed in the hierarchy which should allow for its resolution. Specific classes of orthogonal polynomials characteristic of such periodic hierarchies are thereby generated, while the methods of supersymmetric quantum mechanics then lead to generalised Rodrigues formulae and recursion relations for such polynomials. The approach also offers the practical prospect of quantum modelling through the engineering of quantum potentials from experimental energy spectra. In this paper, these ideas are presented and solved explicitly for the cases N= 1 and N= 2. The latter case is related to the generalised Laguerre polynomials, for which indeed new results are thereby obtained. In the context of dressing chains and deformed polynomial Heisenberg algebras, some partial results for N⩾ 3 also exist in the literature, which should be relevant to a complete study of the N⩾ 3 general periodic hierarchies.

  5. Understanding the Mechanisms behind Changing People’s Recycling Behavior at Work by Applying a Comprehensive Action Determination Model

    Directory of Open Access Journals (Sweden)

    Sunita Prugsamatz Ofstad

    2017-02-01

    Full Text Available This study moves toward a better understanding of the mechanisms behind changing people’s recycling behavior at work by mapping out which pathways and variables change in recycling behavior as triggered by interventions. A questionnaire was designed based on the theory of planned behaviour, the norm-activation model, habits, and a comprehensive action determination model (CADM. The data was collected in two rounds: before the intervention and after a three-month pilot period with implemented interventions using a sample of n = 1269 students and employees. The CADM model appears to be a good fit with the data. The results from the structural equation modelling indicate the pathways to influencing behavioural change. The most important psychological variables accounting for waste separation behaviour are intentions, perceived behavioural control, personal norms, social norms and habits. No difference in waste separation behaviour was observed in the control building. Interventions targeting the increase in waste separation raised participants’ intentions to engage in such behaviour. Results indicate that waste separation at work must go beyond technical aspects to include various key elements of sustainability to ensure success. Furthermore, understanding human behavior is key in determining the performance and success of an integrated and effective recycling intervention strategy.

  6. Mechanisms of radiation interaction with DNA: Potential implications for radiation protection

    International Nuclear Information System (INIS)

    Sinclair, W.K.; Fry, R.J.M.

    1987-01-01

    An overview of presentations and discussions which took place at the US Department of Energy/Commission of European Communities (DOE/CEC) workshop on ''Mechanisms of Radiation Interaction with DNA: Potential Implications for Radiation Protection,'' held at San Diego, California, January 21-22, 1987, is provided. The Department has traditionally supported fundamental research on interactions of ionizing radiation with different biological systems and at all levels of biological organization. The aim of this workshop was to review the base of knowledge in the area of mechanisms of radiation action at the DNA level, and to explore ways in which this information can be applied to the development of scientifically sound concepts and procedures for use in the field of radiation protection

  7. Fundamental transport mechanisms, fabrication and potential applications of nanoporous atomically thin membranes

    Science.gov (United States)

    Wang, Luda; Boutilier, Michael S. H.; Kidambi, Piran R.; Jang, Doojoon; Hadjiconstantinou, Nicolas G.; Karnik, Rohit

    2017-06-01

    Graphene and other two-dimensional materials offer a new approach to controlling mass transport at the nanoscale. These materials can sustain nanoscale pores in their rigid lattices and due to their minimum possible material thickness, high mechanical strength and chemical robustness, they could be used to address persistent challenges in membrane separations. Here we discuss theoretical and experimental developments in the emerging field of nanoporous atomically thin membranes, focusing on the fundamental mechanisms of gas- and liquid-phase transport, membrane fabrication techniques and advances towards practical application. We highlight potential functional characteristics of the membranes and discuss applications where they are expected to offer advantages. Finally, we outline the major scientific questions and technological challenges that need to be addressed to bridge the gap from theoretical simulations and proof-of-concept experiments to real-world applications.

  8. A Gut Feeling to Cure Diabetes: Potential Mechanisms of Diabetes Remission after Bariatric Surgery

    Directory of Open Access Journals (Sweden)

    Young Min Cho

    2014-12-01

    Full Text Available A cure for type 2 diabetes was once a mere dream but has now become a tangible and achievable goal with the unforeseen success of bariatric surgery in the treatment of both obesity and type 2 diabetes. Popular bariatric procedures such as Roux-en-Y gastric bypass and sleeve gastrectomy exhibit high rates of diabetes remission or marked improvement in glycemic control. However, the mechanism of diabetes remission following these procedures is still elusive and appears to be very complex and encompasses multiple anatomical and physiological changes. In this article, calorie restriction, improved β-cell function, improved insulin sensitivity, and alterations in gut physiology, bile acid metabolism, and gut microbiota are reviewed as potential mechanisms of diabetes remission after Roux-en-Y gastric bypass and sleeve gastrectomy.

  9. Mechanism of Action and Clinical Potential of Fingolimod for the Treatment of Stroke

    Directory of Open Access Journals (Sweden)

    Wentao Li

    2016-08-01

    Full Text Available Fingolimod (FTY720 is an orally bio-available immunomodulatory drug currently approved by the FDA for the treatment of multiple sclerosis. Currently, there is a significant interest in the potential benefits of FTY720 on stroke outcomes. FTY720 and the sphingolipid signaling pathway it modulates has a ubiquitous presence in the central nervous system and both rodent models and pilot clinical trials seem to indicate that the drug may improve overall functional recovery in different stroke subtypes. Although the precise mechanisms behind these beneficial effects are yet unclear, there is evidence that FTY720 has a role in regulating cerebrovascular responses, blood brain barrier permeability, and cell survival in the event of cerebrovascular insult. In this article, we critically review the data obtained from the latest laboratory findings and clinical trials involving both ischemic and hemorrhagic stroke, and attempt to form a cohesive picture of FTY720’s mechanisms of action in stroke

  10. On understanding the relationship between structure in the potential surface and observables in classical dynamics: A functional sensitivity analysis approach

    International Nuclear Information System (INIS)

    Judson, R.S.; Rabitz, H.

    1987-01-01

    The relationship between structure in the potential surface and classical mechanical observables is examined by means of functional sensitivity analysis. Functional sensitivities provide maps of the potential surface, highlighting those regions that play the greatest role in determining the behavior of observables. A set of differential equations for the sensitivities of the trajectory components are derived. These are then solved using a Green's function method. It is found that the sensitivities become singular at the trajectory turning points with the singularities going as eta -3 /sup // 2 , with eta being the distance from the nearest turning point. The sensitivities are zero outside of the energetically and dynamically allowed region of phase space. A second set of equations is derived from which the sensitivities of observables can be directly calculated. An adjoint Green's function technique is employed, providing an efficient method for numerically calculating these quantities. Sensitivity maps are presented for a simple collinear atom--diatom inelastic scattering problem and for two Henon--Heiles type Hamiltonians modeling

  11. Maternal childhood trauma, postpartum depression, and infant outcomes: Avoidant affective processing as a potential mechanism.

    Science.gov (United States)

    Choi, Karmel W; Sikkema, Kathleen J; Vythilingum, Bavi; Geerts, Lut; Faure, Sheila C; Watt, Melissa H; Roos, Annerine; Stein, Dan J

    2017-03-15

    Women who have experienced childhood trauma may be at risk for postpartum depression, increasing the likelihood of negative outcomes among their children. Predictive pathways from maternal childhood trauma to child outcomes, as mediated by postpartum depression, require investigation. A longitudinal sample of South African women (N=150) was followed through pregnancy and postpartum. Measures included maternal trauma history reported during pregnancy; postpartum depression through six months; and maternal-infant bonding, infant development, and infant physical growth at one year. Structural equation models tested postpartum depression as a mediator between maternal experiences of childhood trauma and children's outcomes. A subset of women (N=33) also participated in a lab-based emotional Stroop paradigm, and their responses to fearful stimuli at six weeks were explored as a potential mechanism linking maternal childhood trauma, postpartum depression, and child outcomes. Women with childhood trauma experienced greater depressive symptoms through six months postpartum, which then predicted negative child outcomes at one year. Mediating effects of postpartum depression were significant, and persisted for maternal-infant bonding and infant growth after controlling for covariates and antenatal distress. Maternal avoidance of fearful stimuli emerged as a potential affective mechanism. Limitations included modest sample size, self-report measures, and unmeasured potential confounders. Findings suggest a mediating role of postpartum depression in the intergenerational transmission of negative outcomes. Perinatal interventions that address maternal trauma histories and depression, as well as underlying affective mechanisms, may help interrupt cycles of disadvantage, particularly in high-trauma settings such as South Africa. Copyright © 2017. Published by Elsevier B.V.

  12. A review of potential neurotoxic mechanisms among three chlorinated organic solvents

    International Nuclear Information System (INIS)

    Bale, Ambuja S.; Barone, Stan; Scott, Cheryl Siegel; Cooper, Glinda S.

    2011-01-01

    The potential for central nervous system depressant effects from three widely used chlorinated solvents, trichloroethylene (TCE), perchloroethylene (PERC), and dichloromethane (DCM), has been shown in human and animal studies. Commonalities of neurobehavioral and neurophysiological changes for the chlorinated solvents in in vivo studies suggest that there is a common mechanism(s) of action in producing resultant neurotoxicological consequences. The purpose of this review is to examine the mechanistic studies conducted with these chlorinated solvents and to propose potential mechanisms of action for the different neurological effects observed. Mechanistic studies indicate that this solvent class has several molecular targets in the brain. Additionally, there are several pieces of evidence from animal studies indicating this solvent class alters neurochemical functions in the brain. Although earlier evidence indicated that these three chlorinated solvents perturb the lipid bilayer, more recent data suggest an interaction between several specific neuronal receptors produces the resultant neurobehavioral effects. Collectively, TCE, PERC, and DCM have been reported to interact directly with several different classes of neuronal receptors by generally inhibiting excitatory receptors/channels and potentiating the function of inhibitory receptors/channels. Given this mechanistic information and available studies for TCE, DCM, and PERC, we provide hypotheses on primary targets (e.g. ion channel targets) that appear to be most influential in producing the resultant neurological effects. - Research highlights: → Comparison of neurological effects among TCE, PERC, and DCM. → Correlation of mechanistic findings to neurological effects. → Data support that TCE, PERC, and DCM interact with several ion channels to produce neurological changes.

  13. Computational Design of a pH Stable Enzyme: Understanding Molecular Mechanism of Penicillin Acylase's Adaptation to Alkaline Conditions

    Science.gov (United States)

    Suplatov, Dmitry; Panin, Nikolay; Kirilin, Evgeny; Shcherbakova, Tatyana; Kudryavtsev, Pavel; Švedas, Vytas

    2014-01-01

    Protein stability provides advantageous development of novel properties and can be crucial in affording tolerance to mutations that introduce functionally preferential phenotypes. Consequently, understanding the determining factors for protein stability is important for the study of structure-function relationship and design of novel protein functions. Thermal stability has been extensively studied in connection with practical application of biocatalysts. However, little work has been done to explore the mechanism of pH-dependent inactivation. In this study, bioinformatic analysis of the Ntn-hydrolase superfamily was performed to identify functionally important subfamily-specific positions in protein structures. Furthermore, the involvement of these positions in pH-induced inactivation was studied. The conformational mobility of penicillin acylase in Escherichia coli was analyzed through molecular modeling in neutral and alkaline conditions. Two functionally important subfamily-specific residues, Gluβ482 and Aspβ484, were found. Ionization of these residues at alkaline pH promoted the collapse of a buried network of stabilizing interactions that consequently disrupted the functional protein conformation. The subfamily-specific position Aspβ484 was selected as a hotspot for mutation to engineer enzyme variant tolerant to alkaline medium. The corresponding Dβ484N mutant was produced and showed 9-fold increase in stability at alkaline conditions. Bioinformatic analysis of subfamily-specific positions can be further explored to study mechanisms of protein inactivation and to design more stable variants for the engineering of homologous Ntn-hydrolases with improved catalytic properties. PMID:24959852

  14. Multiple stressor effects in Chlamydomonas reinhardtii--toward understanding mechanisms of interaction between effects of ultraviolet radiation and chemical pollutants.

    Science.gov (United States)

    Korkaric, Muris; Behra, Renata; Fischer, Beat B; Junghans, Marion; Eggen, Rik I L

    2015-05-01

    The effects of chemical pollutants and environmental stressors, such as ultraviolet radiation (UVR), can interact when organisms are simultaneously exposed, resulting in higher (synergistic) or lower (antagonistic) multiple stressor effects than expected based on the effects of single stressors. Current understanding of interactive effects is limited due to a lack of mechanism-based multiple stressor studies. It has been hypothesized that effect interactions may generally occur if chemical and non-chemical stressors cause similar physiological effects in the organism. To test this hypothesis, we exposed the model green alga Chlamydomonas reinhardtii to combinations of UVR and single chemicals displaying modes of action (MOA) similar or dissimilar to the impact of UVR on photosynthesis. Stressor interactions were analyzed based on the independent action model. Effect interactions were found to depend on the MOA of the chemicals, and also on their concentrations, the exposure time and the measured endpoint. Indeed, only chemicals assumed to cause effects on photosynthesis similar to UVR showed interactions with UVR on photosynthetic yield: synergistic in case of Cd(II) and paraquat and antagonistic in case of diuron. No interaction on photosynthesis was observed for S-metolachlor, which acts dissimilarly to UVR. However, combined effects of S-metolachlor and UVR on algal reproduction were synergistic, highlighting the importance of considering additional MOA of UVR. Possible mechanisms of stressor effect interactions are discussed. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Computational design of a pH stable enzyme: understanding molecular mechanism of penicillin acylase's adaptation to alkaline conditions.

    Directory of Open Access Journals (Sweden)

    Dmitry Suplatov

    Full Text Available Protein stability provides advantageous development of novel properties and can be crucial in affording tolerance to mutations that introduce functionally preferential phenotypes. Consequently, understanding the determining factors for protein stability is important for the study of structure-function relationship and design of novel protein functions. Thermal stability has been extensively studied in connection with practical application of biocatalysts. However, little work has been done to explore the mechanism of pH-dependent inactivation. In this study, bioinformatic analysis of the Ntn-hydrolase superfamily was performed to identify functionally important subfamily-specific positions in protein structures. Furthermore, the involvement of these positions in pH-induced inactivation was studied. The conformational mobility of penicillin acylase in Escherichia coli was analyzed through molecular modeling in neutral and alkaline conditions. Two functionally important subfamily-specific residues, Gluβ482 and Aspβ484, were found. Ionization of these residues at alkaline pH promoted the collapse of a buried network of stabilizing interactions that consequently disrupted the functional protein conformation. The subfamily-specific position Aspβ484 was selected as a hotspot for mutation to engineer enzyme variant tolerant to alkaline medium. The corresponding Dβ484N mutant was produced and showed 9-fold increase in stability at alkaline conditions. Bioinformatic analysis of subfamily-specific positions can be further explored to study mechanisms of protein inactivation and to design more stable variants for the engineering of homologous Ntn-hydrolases with improved catalytic properties.

  16. Scanning electron microscopy-based approach to understand the mechanism underlying the adhesion of dengue viruses on ceramic hydroxyapatite columns.

    Directory of Open Access Journals (Sweden)

    Maiko Saito

    Full Text Available Although ceramic hydroxyapatite (HAp chromatography has been used as an alternative method ultracentrifugation for the production of vaccines, the mechanism of virus separation is still obscure. In order to begin to understand the mechanisms of virus separation, HAp surfaces were observed by scanning electron microscopy after chromatography with dengue viruses. When these processes were performed without elution and with a 10-207 mM sodium phosphate buffer gradient elution, dengue viruses that were adsorbed to HAp were disproportionately located in the columns. However, when eluted with a 10-600 mM sodium phosphate buffer gradient, few viruses were observed on the HAp surface. After incubating the dengue viruses that were adsorbed on HAp beads at 37°C and 2°C, the sphericity of the dengue viruses were reduced with an increase in incubation temperature. These results suggested that dengue virus was adsorbed to the HAp surface by electronic interactions and could be eluted by high-salt concentration buffers, which are commonly used in protein purification. Furthermore, virus fusion was thought to occur with increasing temperature, which implied that virus-HAp adhesion was similar to virus-cell adhesion.

  17. Potential of AbiS as defence mechanism determined by conductivity measurement

    DEFF Research Database (Denmark)

    Holubová, Jitka; Josephsen, Jytte

    2007-01-01

    Aim: To compare pH and conductivity used in the determination of growth in reconstituted skim milk (RSM), to determine whether the presence of one or two plasmids in Lactococcus lactis had any influence on growth, and whether AbiS improved bacteriophages resistance of L. lactis. Methods and Results...... either AbiS1 or the restriction modification system LlaBIII was present. Conclusions: The earliest detection of growth was observed by measuring pH, rather than conductance. The plasmid-encoded AbiS system has a potential to be used as a phage resistance mechanisms in L. lactis during milk fermentations...

  18. Mechanically Reconfigurable Microstrip Lines Loaded with Stepped Impedance Resonators and Potential Applications

    Directory of Open Access Journals (Sweden)

    J. Naqui

    2014-01-01

    Full Text Available This paper is focused on exploring the possibilities and potential applications of microstrip transmission lines loaded with stepped impedance resonators (SIRs etched on top of the signal strip, in a separated substrate. It is shown that if the symmetry plane of the line (a magnetic wall is perfectly aligned with the electric wall of the SIR at the fundamental resonance, the line is transparent. However, if symmetry is somehow ruptured, a notch in the transmission coefficient appears. The notch frequency and depth can thus be mechanically controlled, and this property can be of interest for the implementation of sensors and barcodes, as it is discussed.

  19. Cannabinoids from Cannabis sp.: mechanism of their activity and potential health benefits in human body

    OpenAIRE

    Dąbrowski, Grzegorz; Skrajda, Marta

    2017-01-01

    Dąbrowski Grzegorz, Skrajda Marta, Cannabinoids from Cannabis sp.: mechanism of their activity and potential health benefits in human body. Journal of Education, Health and Sport. 2017;7(8):936-945. eISSN 2391-8306. DOI http://dx.doi.org/10.5281/zenodo.995625 http://ojs.ukw.edu.pl/index.php/johs/article/view/4876 The journal has had 7 points in Ministry of Science and Higher Education parametric evaluation. Part B item 1223 (26.01.2017). 1223 Jo...

  20. Prediction of Tetraoxygen Reaction Mechanism with Sulfur Atom on the Singlet Potential Energy Surface

    Directory of Open Access Journals (Sweden)

    Ashraf Khademzadeh

    2014-01-01

    Full Text Available The mechanism of S+O4 (D2h reaction has been investigated at the B3LYP/6-311+G(3df and CCSD levels on the singlet potential energy surface. One stable complex has been found for the S+O4 (D2h reaction, IN1, on the singlet potential energy surface. For the title reaction, we obtained four kinds of products at the B3LYP level, which have enough thermodynamic stability. The results reveal that the product P3 is spontaneous and exothermic with −188.042 and −179.147 kcal/mol in Gibbs free energy and enthalpy of reaction, respectively. Because P1 adduct is produced after passing two low energy level transition states, kinetically, it is the most favorable adduct in the 1S+1O4 (D2h atmospheric reactions.

  1. Plant-Microbial Interactions Define Potential Mechanisms of Organic Matter Priming in the Rhizosphere

    Science.gov (United States)

    Zhalnina, K.; Cho, H. J.; Hao, Z.; Mansoori, N.; Karaoz, U.; Jenkins, S.; White, R. A., III; Lipton, M. S.; Deng, K.; Zhou, J.; Pett-Ridge, J.; Northen, T.; Firestone, M. K.; Brodie, E.

    2015-12-01

    In the rhizosphere, metabolic processes of plants and microorganisms are closely coupled, and together with soil minerals, their interactions regulate the turnover of soil organic C (SOC). Plants provide readily assimilable metabolites for microorganisms through exudation, and it has been hypothesized that increasing concentrations of exudate C may either stimulate or suppress rates of SOC mineralization (rhizosphere priming). Both positive and negative rhizosphere priming has been widely observed, however the underlying mechanisms remain poorly understood. To begin to identify the molecular mechanisms underlying rhizosphere priming, we isolated a broad range of soil bacteria from a Mediterranean grassland dominated by annual grass. Thirty-nine heterotrophic bacteria were selected for genome sequencing and both rRNA gene analysis and metagenome coverage suggest that these isolates represent naturally abundant strain variants. We analyzed their genomes for potential metabolic traits related to life in the rhizosphere and the decomposition of polymeric SOC. While the two dominant groups, Alphaproteobacteria and Actinobacteria, were enriched in polymer degrading enzymes, Alphaproteobacterial isolates contained greater gene copies of transporters related to amino acid, organic acid and auxin uptake or export, suggesting an enhanced metabolic potential for life in the root zone. To verify this metabolic potential, we determined the enzymatic activities of these isolates and revealed preferences of strains to degrade certain polymers (xylan, cellulose or lignin). Fourier Transform Infrared spectroscopy is being used to determine which polymeric components of plant roots are targeted by specific strains and how exudates may impact their degradation. To verify the potential of isolates to assimilate root exudates and export key metabolites we are using LC-MS/MS based exometabolomic profiling. The traits hypothesized and verified here (transporters, enzymes, exudate uptake

  2. Chemical compounds from anthropogenic environment and immune evasion mechanisms: potential interactions.

    Science.gov (United States)

    Kravchenko, Julia; Corsini, Emanuela; Williams, Marc A; Decker, William; Manjili, Masoud H; Otsuki, Takemi; Singh, Neetu; Al-Mulla, Faha; Al-Temaimi, Rabeah; Amedei, Amedeo; Colacci, Anna Maria; Vaccari, Monica; Mondello, Chiara; Scovassi, A Ivana; Raju, Jayadev; Hamid, Roslida A; Memeo, Lorenzo; Forte, Stefano; Roy, Rabindra; Woodrick, Jordan; Salem, Hosni K; Ryan, Elizabeth P; Brown, Dustin G; Bisson, William H; Lowe, Leroy; Lyerly, H Kim

    2015-06-01

    An increasing number of studies suggest an important role of host immunity as a barrier to tumor formation and progression. Complex mechanisms and multiple pathways are involved in evading innate and adaptive immune responses, with a broad spectrum of chemicals displaying the potential to adversely influence immunosurveillance. The evaluation of the cumulative effects of low-dose exposures from the occupational and natural environment, especially if multiple chemicals target the same gene(s) or pathway(s), is a challenge. We reviewed common environmental chemicals and discussed their potential effects on immunosurveillance. Our overarching objective was to review related signaling pathways influencing immune surveillance such as the pathways involving PI3K/Akt, chemokines, TGF-β, FAK, IGF-1, HIF-1α, IL-6, IL-1α, CTLA-4 and PD-1/PDL-1 could individually or collectively impact immunosurveillance. A number of chemicals that are common in the anthropogenic environment such as fungicides (maneb, fluoxastrobin and pyroclostrobin), herbicides (atrazine), insecticides (pyridaben and azamethiphos), the components of personal care products (triclosan and bisphenol A) and diethylhexylphthalate with pathways critical to tumor immunosurveillance. At this time, these chemicals are not recognized as human carcinogens; however, it is known that they these chemicalscan simultaneously persist in the environment and appear to have some potential interfere with the host immune response, therefore potentially contributing to promotion interacting with of immune evasion mechanisms, and promoting subsequent tumor growth and progression. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  3. Thermo-mechanical stress analysis of cryopreservation in cryobags and the potential benefit of nanowarming.

    Science.gov (United States)

    Solanki, Prem K; Bischof, John C; Rabin, Yoed

    2017-06-01

    Cryopreservation by vitrification is the only promising solution for long-term organ preservation which can save tens of thousands of lives across the world every year. One of the challenges in cryopreservation of large-size tissues and organs is to prevent fracture formation due to the tendency of the material to contract with temperature. The current study focuses on a pillow-like shape of a cryobag, while exploring various strategies to reduce thermo-mechanical stress during the rewarming phase of the cryopreservation protocol, where maximum stresses are typically found. It is demonstrated in this study that while the level of stress may generally increase with the increasing amount of CPA filled in the cryobag, the ratio between width and length of the cryobag play a significant role. Counterintuitively, the overall maximum stress is not found when the bag is filled to its maximum capacity (when the filled cryobag resembles a sphere). Parametric investigation suggests that reducing the initial rewarming rate between the storage temperature and the glass transition temperature may dramatically decrease the thermo-mechanical stress. Adding a temperature hold during rewarming at the glass transition temperature may reduce the thermo-mechanical stress in some cases, but may have an adverse effect in other cases. Finally, it is demonstrated that careful incorporation of volumetric heating by means on nanoparticles in an alternating magnetic field, or nanowarming, can dramatically reduce the resulting thermo-mechanical stress. These observations display the potential benefit of a thermo-mechanical design of the cryopreservation protocols in order to prevent structural damage. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Organizational mechanism for imlementation of the travel agency financial potential development strategy

    Directory of Open Access Journals (Sweden)

    І.V. Saukh

    2017-03-01

    Full Text Available The article discusses the implementation of the financial development strategy as a set of means required for its accomplishment, including consecutive execution of this strategy, creation of the communication channels, distribution of duties between the parties to the strategic plan, and formation of the system of strategic control. The research analyzes the scientific and methodological approaches used to implement the strategy and form the organizational mechanism of this process within the development of the company's financial potential, based on the use of systemic approach and the concept of strategic change. The paper reveals that travel companies are not able to apply the unified approach to accomplish this strategy, because the process of its implementation is creative and informal. Moreover, it is greatly influenced by the activity of each business. The organizational mechanism of this strategic development embraces a complex of levels, stages, instruments and methods of organizational change. Their systemic application contributes to the development of the company's financial strength. The structure of this organizational mechanism is described as the result of the analysis of traditional and situational methodological approaches to the strategy's formalization and implementation. It centers around the concept of strategic change and seamless cooperation of the target, subject-to-object (injunctive and process-related (regulatory subsystems of the developed mechanism. The mechanism allows to pinpoint and implement the strategies aimed at the development of the company's financial resources and its other structural units. In order to simplify the process of coordination of the subjects implementing the strategy in real-time business activities, the operogram for strategic analysis of the financial development is created. It can be used to optimize the duration of this analysis and allocate the company’s resources in the most

  5. Assessment of clean development mechanism potential of large-scale energy efficiency measures in heavy industries

    International Nuclear Information System (INIS)

    Hayashi, Daisuke; Krey, Matthias

    2007-01-01

    This paper assesses clean development mechanism (CDM) potential of large-scale energy efficiency measures in selected heavy industries (iron and steel, cement, aluminium, pulp and paper, and ammonia) taking India and Brazil as examples of CDM project host countries. We have chosen two criteria for identification of the CDM potential of each energy efficiency measure: (i) emission reductions volume (in CO 2 e) that can be expected from the measure and (ii) likelihood of the measure passing the additionality test of the CDM Executive Board (EB) when submitted as a proposed CDM project activity. The paper shows that the CDM potential of large-scale energy efficiency measures strongly depends on the project-specific and country-specific context. In particular, technologies for the iron and steel industry (coke dry quenching (CDQ), top pressure recovery turbine (TRT), and basic oxygen furnace (BOF) gas recovery), the aluminium industry (point feeder prebake (PFPB) smelter), and the pulp and paper industry (continuous digester technology) offer promising CDM potential

  6. Towards a better understanding of flood generation and surface water inundation mechanisms using NASA remote sensing data products

    Science.gov (United States)

    Lucey, J.; Reager, J. T., II; Lopez, S. R.

    2017-12-01

    Floods annually cause several weather-related fatalities and financial losses. According to NOAA and FEMA, there were 43 deaths and 18 billion dollars paid out in flood insurance policies during 2005. The goal of this work is to improve flood prediction and flood risk assessment by creating a general model of predictability of extreme runoff generation using various NASA products. Using satellite-based flood inundation observations, we can relate surface water formation processes to changes in other hydrological variables, such as precipitation, storage and soil moisture, and understand how runoff generation response to these forcings is modulated by local topography and land cover. Since it is known that a flood event would cause an abnormal increase in surface water, we examine these underlying physical relationships in comparison with the Dartmouth Flood Observatory archive of historic flood events globally. Using ground water storage observations (GRACE), precipitation (TRMM or GPCP), land use (MODIS), elevation (SRTM) and surface inundation levels (SWAMPS), an assessment of geological and climate conditions can be performed for any location around the world. This project utilizes multiple linear regression analysis evaluating the relationship between surface water inundation, total water storage anomalies and precipitation values, grouped by average slope or land use, to determine their statistical relationships and influences on inundation data. This research demonstrates the potential benefits of using global data products for early flood prediction and will improve our understanding of runoff generation processes.

  7. A mechanically-induced colon cancer cell population shows increased metastatic potential

    KAUST Repository

    Tang, Xin

    2014-05-29

    , phenotypical, and mechanical signatures between the two cell types. To our knowledge, this is the first study that explores the molecular mechanism of E-R transition, which may greatly increase our understanding of the mechanisms of cancer mechanical microenvironment and initiation of cancer metastasis. 2014 Tang et al.; licensee BioMed Central Ltd.

  8. Genomics-based identification of molecular mechanisms behind the cancer preventive action of phytochemicals: potential and challenges.

    Science.gov (United States)

    Kok, Theo M C M de; Breda, Simone G J van; Briedé, Jacob J

    2012-01-01

    High intake of dietary phytochemicals, non-nutritive compounds found in vegetables and fruits, has been associated with a decreased risk of various types of cancer. With the introduction of new "omics" research approaches, technologies providing large scale and holistic data on biological responses to dietary or environmental factors, our understanding of the molecular mechanisms of the preventive action of individual phytochemicals has started to increase rapidly. This understanding contributes to the biological plausibility of the observed link between fruit and vegetable consumption and decreased cancer risk in epidemiological studies. In this mini-review, we present an overview of the characteristics of the different "omics" techniques, with emphasis on transcriptomics, epigenetics, and the analysis of single nucleotide polymorphisms, and evaluate their implications in studies on dietary phytochemicals. We focus particularly on studies in human cell cultures in vitro and in human population studies and discuss the potential and different challenges offered by each technique, as well as future perspectives on applications of these new tools in nutritional genomics research.

  9. Integrated modeling and field study of potential mechanisms forinduced seismicity at The Geysers Goethermal Field, California

    Energy Technology Data Exchange (ETDEWEB)

    Rutqvist, Jonny; Majer, Ernie; Oldenburg, Curt; Peterson, John; Vasco, Don

    2006-06-07

    In this paper, we present progress made in a study aimed atincreasing the understanding of the relative contributions of differentmechanisms that may be causing the seismicity occurring at The Geysersgeothermal field, California. The approach we take is to integrate: (1)coupled reservoir geomechanical numerical modeling, (2) data fromrecently upgraded and expanded NCPA/Calpine/LBNL seismic arrays, and (3)tens of years of archival InSAR data from monthly satellite passes. Wehave conducted a coupled reservoir geomechanical analysis to studypotential mechanisms induced by steam production. Our simulation resultscorroborate co-locations of hypocenter field observations of inducedseismicity and their correlation with steam production as reported in theliterature. Seismic and InSAR data are being collected and processed foruse in constraining the coupled reservoir geomechanicalmodel.

  10. Rapid, computer vision-enabled murine screening system identifies neuropharmacological potential of two new mechanisms

    Directory of Open Access Journals (Sweden)

    Steven L Roberds

    2011-09-01

    Full Text Available The lack of predictive in vitro models for behavioral phenotypes impedes rapid advancement in neuropharmacology and psychopharmacology. In vivo behavioral assays are more predictive of activity in human disorders, but such assays are often highly resource-intensive. Here we describe the successful application of a computer vision-enabled system to identify potential neuropharmacological activity of two new mechanisms. The analytical system was trained using multiple drugs that are used clinically to treat depression, schizophrenia, anxiety, and other psychiatric or behavioral disorders. During blinded testing the PDE10 inhibitor TP-10 produced a signature of activity suggesting potential antipsychotic activity. This finding is consistent with TP-10’s activity in multiple rodent models that is similar to that of clinically used antipsychotic drugs. The CK1ε inhibitor PF-670462 produced a signature consistent with anxiolytic activity and, at the highest dose tested, behavioral effects similar to that of opiate analgesics. Neither TP-10 nor PF-670462 was included in the training set. Thus, computer vision-based behavioral analysis can facilitate drug discovery by identifying neuropharmacological effects of compounds acting through new mechanisms.

  11. Seawater-drowning-induced acute lung injury: From molecular mechanisms to potential treatments.

    Science.gov (United States)

    Jin, Faguang; Li, Congcong

    2017-06-01

    Drowning is a crucial public safety problem and is the third leading cause of accidental fatality, claiming ~372,000 lives annually, worldwide. In near-drowning patients, acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) is one of the most common complications. Approximately 1/3 of near-drowning patients fulfill the criteria for ALI or ARDS. In the present article, the current literature of near-drowning, pathophysiologic changes and the molecular mechanisms of seawater-drowning-induced ALI and ARDS was reviewed. Seawater is three times more hyperosmolar than plasma, and following inhalation of seawater the hyperosmotic seawater may cause serious injury in the lung and alveoli. The perturbing effects of seawater may be primarily categorized into insufficiency of pulmonary surfactant, blood-air barrier disruption, formation of pulmonary edema, inflammation, oxidative stress, autophagy, apoptosis and various other hypertonic stimulation. Potential treatments for seawater-induced ALI/ARDS were also presented, in addition to suggestions for further studies. A total of nine therapeutic strategies had been tested and all had focused on modulating the over-activated immunoreactions. In conclusion, seawater drowning is a complex injury process and the exact mechanisms and potential treatments require further exploration.

  12. Seawater-drowning-induced acute lung injury: From molecular mechanisms to potential treatments

    Science.gov (United States)

    Jin, Faguang; Li, Congcong

    2017-01-01

    Drowning is a crucial public safety problem and is the third leading cause of accidental fatality, claiming ~372,000 lives annually, worldwide. In near-drowning patients, acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) is one of the most common complications. Approximately 1/3 of near-drowning patients fulfill the criteria for ALI or ARDS. In the present article, the current literature of near-drowning, pathophysiologic changes and the molecular mechanisms of seawater-drowning-induced ALI and ARDS was reviewed. Seawater is three times more hyperosmolar than plasma, and following inhalation of seawater the hyperosmotic seawater may cause serious injury in the lung and alveoli. The perturbing effects of seawater may be primarily categorized into insufficiency of pulmonary surfactant, blood-air barrier disruption, formation of pulmonary edema, inflammation, oxidative stress, autophagy, apoptosis and various other hypertonic stimulation. Potential treatments for seawater-induced ALI/ARDS were also presented, in addition to suggestions for further studies. A total of nine therapeutic strategies had been tested and all had focused on modulating the over-activated immunoreactions. In conclusion, seawater drowning is a complex injury process and the exact mechanisms and potential treatments require further exploration. PMID:28587319

  13. Gender-related differences in irritable bowel syndrome: Potential mechanisms of sex hormones

    Science.gov (United States)

    Meleine, Mathieu; Matricon, Julien

    2014-01-01

    According to epidemiological studies, twice as many women as men are affected by irritable bowel syndrome (IBS) in western countries, suggesting a role for sex hormones in IBS pathophysiology. Despite growing evidence about the implications of sex hormones in IBS symptom modulation, data on mechanisms by which they influence disease development are sparse. This review aims to determine the state of knowledge about the role of sex hormones in sensorimotor dysfunctions and to address the possible interplay of sex hormones with common risk factors associated with IBS. The scientific bibliography was searched using the following keywords: irritable bowel syndrome, sex, gender, ovarian hormone, estradiol, progesterone, testosterone, symptoms, pain, sensitivity, motility, permeability, stress, immune system, brain activity, spinal, supraspinal, imaging. Ovarian hormones variations along the menstrual cycle affect sensorimotor gastrointestinal function in both healthy and IBS populations. They can modulate pain processing by interacting with neuromodulator systems and the emotional system responsible for visceral pain perception. These hormones can also modulate the susceptibility to stress, which is a pivotal factor in IBS occurrence and symptom severity. For instance, estrogen-dependent hyper-responsiveness to stress can promote immune activation or impairments of gut barrier function. In conclusion, whereas it is important to keep in mind that ovarian hormones cannot be considered as a causal factor of IBS, they arguably modulate IBS onset and symptomatology. However, our understanding of the underlying mechanisms remains limited and studies assessing the link between IBS symptoms and ovarian hormone levels are needed to improve our knowledge of the disease evolution with regard to gender. Further studies assessing the role of male hormones are also needed to understand fully the role of sex hormones in IBS. Finally, investigation of brain-gut interactions is critical

  14. Genomic sequencing of a strain of Acinetobacter baumannii and potential mechanisms to antibiotics resistance.

    Science.gov (United States)

    Zhao, Lei; Li, Hongru; Zhu, Ziwen; Wakefield, Mark R; Fang, Yujiang; Ye, Ying

    2017-06-01

    Acinetobacter baumannii has been becoming a great challenge to clinicians due to their resistance to almost all available antibiotics. In this study, we sequenced the genome from a multiple antibiotics resistant Acinetobacter baumannii stain which was named A. baumannii-1isolated from China by SMRT sequencing technology to explore its potential mechanisms to antibiotic resistance. We found that several mechanisms might contribute to the antibiotic resistance of Acinetobacter baumannii. Specifically, we found that SNP in genes associated with nucleotide excision repair and ABC transporter might contribute to its resistance to multiple antibiotics; we also found that specific genes associated with bacterial DNA integration and recombination, DNA-mediated transposition and response to antibiotics might contribute to its resistance to multiple antibiotics; Furthermore, specific genes associated with penicillin and cephalosporin biosynthetic pathway and specific genes associated with CHDL and MBL β-lactamase genes might contribute to its resistance to multiple antibiotics. Thus, the detailed mechanisms by which Acinetobacter baumannii show extensive resistance to multiple antibiotics are very complicated. Such a study might be helpful to develop new strategies to control Acinetobacter baumannii infection. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. An overview of potential molecular mechanisms involved in VSMC phenotypic modulation.

    Science.gov (United States)

    Zhang, Ming-Jie; Zhou, Yi; Chen, Lei; Wang, Yan-Qin; Wang, Xu; Pi, Yan; Gao, Chang-Yue; Li, Jing-Cheng; Zhang, Li-Li

    2016-02-01

    The fully differentiated medial vascular smooth muscle cells (VSMCs) of mature vessels keep quiescent and contractile. However, VSMC can exhibit the plasticity in phenotype switching from a differentiated and contractile phenotype to a dedifferentiated state in response to alterations in local environmental cues, which is called phenotypic modulation or switching. Distinguishing from its differentiated state expressing more smooth muscle (SM)-specific/selective proteins, the phenotypic modulation in VSMC is characterized by an increased rate of proliferation, migration, synthesis of extracellular matrix proteins and decreased expression of SM contractile proteins. Although it has been well demonstrated that phenotypic modulation of VSMC contributes to the occurrence and progression of many proliferative vascular diseases, little is known about the details of the molecular mechanisms of VSMC phenotypic modulation. Growing evidence suggests that variety of molecules including microRNAs, cytokines and biochemical factors, membrane receptors, ion channels, cytoskeleton and extracellular matrix play important roles in controlling VSMC phenotype. The focus of the present review is to provide an overview of potential molecular mechanisms involved in VSMC phenotypic modulation in recent years. To clarify VSMC differentiation and phenotypic modulation mechanisms will contribute to producing cell-based therapeutic interventions for aberrant VSMC differentiation-related diseases.

  16. Biological Communities in Desert Varnish and Potential Implications for Varnish Formation Mechanisms

    Science.gov (United States)

    Lang-Yona, Naama; Maier, Stefanie; Macholdt, Dorothea; Rodriguez-Caballero, Emilio; Müller-Germann, Isabell; Yordanova, Petya; Jochum, Klaus-Peter; Andreae, Meinrat O.; Pöschl, Ulrich; Weber, Bettina; Fröhlich-Nowoisky, Janine

    2017-04-01

    Desert varnishes are thin, orange to black coatings found on rocks in arid and semi-arid environments on Earth. The formation mechanisms of rock varnish are still under debate and the involvement of microorganisms in this process remains unclear. In this work we aimed to identify the microbial community occurring in rock varnish to potentially gain insights into the varnish formation mechanism. For this purpose, rocks coated with desert varnish were collected from the Anza-Borrego Desert, California, USA, as well as soils from underneath the rocks. DNA from both varnish coatings and soil samples was extracted and subsequently used for metagenomic analysis, as well as for q-PCR analyses for specific species quantification. The element composition of the varnish coatings was analyzed and compared to the soil samples. Rock varnish shows similar depleted elements, compared to soil, but Mn and Pb are 50-60 times enriched compared to the soil samples, and about 100 times enriched compared to the upper continental crust. Our genomic analyses suggest unique populations and different protein functional groups occurring in the varnish compared to soil samples. We discuss these differences and try to shed light on the mechanism of Mn oxyhydroxide production in desert varnish formation.

  17. Integrated network analysis reveals potentially novel molecular mechanisms and therapeutic targets of refractory epilepsies.

    Directory of Open Access Journals (Sweden)

    Hongwei Chu

    Full Text Available Epilepsy is a complex neurological disorder and a significant health problem. The pathogenesis of epilepsy remains obscure in a significant number of patients and the current treatment options are not adequate in about a third of individuals which were known as refractory epilepsies (RE. Network medicine provides an effective approach for studying the molecular mechanisms underlying complex diseases. Here we integrated 1876 disease-gene associations of RE and located those genes to human protein-protein interaction (PPI network to obtain 42 significant RE-associated disease modules. The functional analysis of these disease modules showed novel molecular pathological mechanisms of RE, such as the novel enriched pathways (e.g., "presynaptic nicotinic acetylcholine receptors", "signaling by insulin receptor". Further analysis on the relationships between current drug targets and the RE-related disease genes showed the rational mechanisms of most antiepileptic drugs. In addition, we detected ten potential novel drug targets (e.g., KCNA1, KCNA4-6, KCNC3, KCND2, KCNMA1, CAMK2G, CACNB4 and GRM1 located in three RE related disease modules, which might provide novel insights into the new drug discovery for RE therapy.

  18. Exploring the MACH Model's Potential as a Metacognitive Tool to Help Undergraduate Students Monitor Their Explanations of Biological Mechanisms

    Science.gov (United States)

    Trujillo, Caleb M.; Anderson, Trevor R.; Pelaez, Nancy J.

    2016-01-01

    When undergraduate biology students learn to explain biological mechanisms, they face many challenges and may overestimate their understanding of living systems. Previously, we developed the MACH model of four components used by expert biologists to explain mechanisms: Methods, Analogies, Context, and How. This study explores the implementation of…

  19. Molecular-level understanding of the adsorption mechanism of a graphite-binding peptide at the water/graphite interface.

    Science.gov (United States)

    Penna, M J; Mijajlovic, M; Tamerler, C; Biggs, M J

    2015-07-14

    The association of proteins and peptides with inorganic material has vast technological potential. An understanding of the adsorption of peptides at liquid/solid interfaces on a molecular-level is fundamental to fully realising this potential. Combining our prior work along with the statistical analysis of 100+ molecular dynamics simulations of adsorption of an experimentally identified graphite binding peptide, GrBP5, at the water/graphite interface has been used here to propose a model for the adsorption of a peptide at a liquid/solid interface. This bottom-up model splits the adsorption process into three reversible phases: biased diffusion, anchoring and lockdown. Statistical analysis highlighted the distinct roles played by regions of the peptide studied here throughout the adsorption process: the hydrophobic domain plays a significant role in the biased diffusion and anchoring phases suggesting that the initial impetus for association between the peptide and the interface may be hydrophobic in origin; aromatic residues dominate the interaction between the peptide and the surface in the adsorbed state and the polar region in the middle of the peptide affords a high conformational flexibility allowing strongly interacting residues to maximise favourable interactions with the surface. Reversible adsorption was observed here, unlike in our prior work focused on a more strongly interacting surface. However, this reversibility is unlikely to be seen once the peptide-surface interaction exceeds 10 kcal mol(-1).

  20. Understanding the molecular biology of intervertebral disc degeneration and potential gene therapy strategies for regeneration: a review.

    Science.gov (United States)

    Sampara, Prasanthi; Banala, Rajkiran Reddy; Vemuri, Satish Kumar; Av, Gurava Reddy; Gpv, Subbaiah

    2018-03-22

    Intervertebral disc degeneration (IVDD) is a multi-factorial process characterized by phenotypic and genotypic changes, which leads to low back pain and disability. Prolonged imbalance between anabolism and catabolism in discs alters their composition resulting in progressive loss of proteoglycans and hydration leading to IVDD. The current managements for IVDD are only able to relieve the symptoms but do not address the underlying pathology of degeneration. Researchers have tried to find out differences between the aging and degeneration of the disc. Intense attempts are in progress for identifying the various factors responsible for disc degeneration, as well as strategies for regeneration. Recently biological approaches have gained thrust in the field of IVDD. The present review illustrates the current understanding of intervertebral disc degeneration and aims to put forth recent advancements in regeneration strategies involving different biological therapies such as growth factor, cell, and gene therapy. The potentials and consequences of these therapies are also extensively discussed along with citing the most suitable method, that is, the gene therapy in detail. Initially, gene therapy was mediated by viral vectors but recent progress has enabled researchers to opt for non-virus-mediated gene therapy methods, which ensure that there are no risks of mutagenicity and infection in target cells. With constant efforts, non-virus-mediated gene therapy may prove to be an extremely powerful tool in treatment of IVDD in future.

  1. Understanding the Potential for Patient Engagement in Electronic Consultation and Referral Systems: Lessons From One Safety Net System.

    Science.gov (United States)

    Olayiwola, Jacqueline Nwando; Knox, Margae; Dubé, Kate; Lu, Emily Chen-Yuan; Woldeyesus, Tem; James, Iguehi E; Willard-Grace, Rachel; Tuot, Delphine

    2017-09-20

    To understand patient, primary care clinician (PCC), and subspecialist perspectives on potential, unexplored roles for patients in electronic consultation and referral (eCR) systems. Primary focus group and survey data collected April-November 2015. Zuckerberg San Francisco General Hospital (ZSFG) is part of an integrated public health delivery system. Its mature eCR system was first implemented in 2005. This mixed-methods study synthesizes patient, subspecialist, and PCC perspectives through two patient focus groups in English, Spanish, and Cantonese (n = 6); subspecialist focus groups (n = 2); and an electronic survey of all PCCs (n = 222/634, 35 percent response). Focus groups were audio-recorded and transcribed. Two researchers coded the transcripts to identify recurrent themes. Survey data were analyzed using summary and bivariate statistics. Patients expressed minimal desire to directly engage in eCR, instead of emphasizing their PCC's role in advocating, informing, and finding health solutions. Subspecialists requested more consistent communication to patients about the electronic consultation process. Most PCCs (52 percent) supported patient engagement in the eCR process, particularly patient ability to track consult status and securely message with subspecialists. Results suggest a continuum of opportunities for patients and their caregivers to engage in eCR systems. © Health Research and Educational Trust.

  2. Study of the 3D Euler equations using Clebsch potentials: dual mechanisms for geometric depletion

    Science.gov (United States)

    Ohkitani, Koji

    2018-02-01

    After surveying analyses of the 3D Euler equations using the Clebsch potentials scattered over the literature, we report some preliminary new results. 1. Assuming that flow fields are free from nulls of the impulse and the vorticity fields, we study how constraints imposed by the Clebsch potentials lead to a degenerate geometrical structure, typically in the form of depletion of nonlinearity. We consider a vorticity surface spanned by \\boldsymbol ω and another material vector \\boldsymbol {W} such that \\boldsymbol γ=\\boldsymbol ω× \\boldsymbol {W}, where \\boldsymbol γ is the impulse variable in geometric gauge. We identify dual mechanism for geometric depletion and show that at least of one them is acting if \\boldsymbol {W} does not develop a null. This suggests that formation of singularity in flows endowed with Clebsch potentials is less likely to happen than in more general flows. Some arguments are given towards exclusion of ‘type I’ blowup. A mathematical challenge remains to rule out singularity formation for flows which have Clebsch potentials everywhere. 2. We exploit classical differential geometry kinematically to write down the Gauss-Weingarten equations for the vorticity surface of the Clebsch potential in terms of fluid dynamical variables, as are the first, second and third fundamental forms. In particular, we derive a constraint on the size of the Gaussian curvature near the point of a possible singularity. On the other hand, an application of the Gauss-Bonnet theorem reveals that the tangential curvature of the surface becomes large in the neighborhood of near-singularity. 3. Using spatially-periodic flows with highly-symmetry, i.e. initial conditions of the Taylor-Green vortex and the Kida-Pelz flow, we present explicit formulas of the Clebsch potentials with exceptional singular surfaces where the Clebsch potentials are undefined. This is done by connecting the known expressions with the solenoidal impulse variable (i.e. the

  3. Teachers' Beliefs about the Role of Interaction in Teaching Newtonian Mechanics and Its Influence on Students' Conceptual Understanding of Newton's Third Law

    Science.gov (United States)

    Jauhiainen, Johanna; Koponen, Ismo T.; Lavonen, Jari

    2006-01-01

    Students' conceptual understanding of Newton's third law has been the subject of numerous studies. These studies have often pointed out the importance of addressing the concept of interaction in teaching Newtonian mechanics. In this study, teachers were interviewed in order to examine how they understand interaction and use it in their…

  4. Potential of wind power projects under the Clean Development Mechanism in India

    Directory of Open Access Journals (Sweden)

    Michaelowa Axel

    2007-07-01

    Full Text Available Abstract Background So far, the cumulative installed capacity of wind power projects in India is far below their gross potential (≤ 15% despite very high level of policy support, tax benefits, long term financing schemes etc., for more than 10 years etc. One of the major barriers is the high costs of investments in these systems. The Clean Development Mechanism (CDM of the Kyoto Protocol provides industrialized countries with an incentive to invest in emission reduction projects in developing countries to achieve a reduction in CO2 emissions at lowest cost that also promotes sustainable development in the host country. Wind power projects could be of interest under the CDM because they directly displace greenhouse gas emissions while contributing to sustainable rural development, if developed correctly. Results Our estimates indicate that there is a vast theoretical potential of CO2 mitigation by the use of wind energy in India. The annual potential Certified Emissions Reductions (CERs of wind power projects in India could theoretically reach 86 million. Under more realistic assumptions about diffusion of wind power projects based on past experiences with the government-run programmes, annual CER volumes by 2012 could reach 41 to 67 million and 78 to 83 million by 2020. Conclusion The projections based on the past diffusion trend indicate that in India, even with highly favorable assumptions, the dissemination of wind power projects is not likely to reach its maximum estimated potential in another 15 years. CDM could help to achieve the maximum utilization potential more rapidly as compared to the current diffusion trend if supportive policies are introduced.

  5. College Chemistry Students' Understanding of Potential Energy in the Context of Atomic-Molecular Interactions

    Science.gov (United States)

    Becker, Nicole M.; Cooper, Melanie M.

    2014-01-01

    Understanding the energy changes that occur as atoms and molecules interact forms the foundation for understanding the macroscopic energy changes that accompany chemical processes. In order to identify ways to scaffold students' understanding of the connections between atomic-molecular and macroscopic energy perspectives, we conducted a…

  6. Understanding mechanisms of rarity in pteridophytes: competition and climate change threaten the rare fern Asplenium scolopendrium var. americanum (Aspleniaceae).

    Science.gov (United States)

    Testo, Weston L; Watkins, James E

    2013-11-01

    Understanding the ecology of rare species can inform aspects of conservation strategies; however, the mechanisms of rarity remain elusive for most pteridophytes, which possess independent and ecologically distinct gametophyte and sporophyte generations. To elucidate factors contributing to recent declines of the rare fern Asplenium scolopendrium var. americanum, we studied the ecology and ecophysiology of its gametophyte generation, focusing on responses to competition, temperature, and water stress. Gametophytes of A. scolopendrium var. americanum, its widespread European relative A. scolopendrium var. scolopendrium, and five co-occurring fern species were grown from spores. Gametophytes were grown at 20°C and 25°C, and germination rates, intra- and interspecific competition, desiccation tolerance, and sporophyte production were determined for all species. Gametophytes of A. scolopendrium var. americanum had the lowest rates of germination and sporophyte production among all species studied and exhibited the greatest sensitivity to interspecific competition, temperature increases, and desiccation. Mature gametophytes of A. scolopendrium var. americanum grown at 25°C were 84.6% smaller than those grown at 20°C, and only 1.5% produced sporophytes after 200 d in culture. Similar responses were not observed in other species studied. The recent declines and current status of populations of A. scolopendrium var. americanum are linked to its gametophyte's limited capacity to tolerate competition and physiological stress linked to climate change. This is the first study to develop a mechanistic understanding of rarity and decline in a fern and demonstrates the importance of considering the ecology of the gametophyte in plants with independent sporophyte and gametophyte generations.

  7. Potential Triggering Mechanisms for the 2006-2007 Half Dome Rockfalls, Yosemite National Park, California

    Science.gov (United States)

    Stock, G. M.

    2007-12-01

    Yosemite Valley is one of the most active areas of rockfall in the world, allowing for detailed examination of individual rockfall events. A rockfall database going back to 1857 reveals that more than half of all documented rockfalls were not associated with a recognizable triggering mechanism. Between July 2006 and June 2007, a series of at least eight rockfalls occurred from a single release point on the Northwest Face of Half Dome in eastern Yosemite Valley. The largest of these rockfalls occurred at 18:46 on July 27th, 2007, and had an approximate volume of 735 m3. Interestingly, all of the rockfalls occurred during the summer (June-August), with no apparent activity at the release point during the winter and spring, typically considered peak seasons for rockfall. In addition to mapping rockfall volumes and the distribution of rock debris, I investigated the geologic and hydrologic factors contributing to failure, including bedrock lithology, degree of weathering, joint density and orientation, and release point geometry. I also analyzed a number of potential rockfall triggering mechanisms, including earthquakes, precipitation, freeze-thaw, and thermal stresses. Although a number of factors contributed to weakening of the rock mass, no specific triggering mechanism(s) can be confidently linked to the rockfalls. Rather, the rockfalls likely resulted from progressive strain weakening of an overhanging arch, with initial small rockfalls destabilizing the rock mass to the point that a large failure occurred. The supposition that summertime rockfalls with unrecognized triggers are unusual has been used to support claims that rockfalls below Glacier Point were caused by wastewater discharges, but the 2006-2007 Half Dome rockfalls, which occurred in a wilderness setting, demonstrate that subtle, even unrecognizable, natural processes trigger summertime rockfalls in Yosemite Valley.

  8. Multiple stressor effects in Chlamydomonas reinhardtii – Toward understanding mechanisms of interaction between effects of ultraviolet radiation and chemical pollutants

    Energy Technology Data Exchange (ETDEWEB)

    Korkaric, Muris [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, 8600, Duebendorf (Switzerland); ETH Zürich, Institute of Biogeochemistry and Pollutant Dynamics, 8092 Zürich (Switzerland); Behra, Renata; Fischer, Beat B. [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, 8600, Duebendorf (Switzerland); Junghans, Marion [Swiss Center for Applied Ecotoxicology Eawag-EPFL, 8600, Duebendorf (Switzerland); Eggen, Rik I.L., E-mail: rik.eggen@eawag.ch [Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Environmental Toxicology, 8600, Duebendorf (Switzerland); ETH Zürich, Institute of Biogeochemistry and Pollutant Dynamics, 8092 Zürich (Switzerland)

    2015-05-15

    Highlights: • Systematic study of multiple stressor effects of UVR and chemicals in C. reinhardtii. • UVR and chemicals did not act independently on algal photosynthesis and reproduction. • Multiple stressor effects of UVR and chemicals depended on chemical MOA. • Synergistic effect interactions not limited to oxidative stress inducing chemicals. • Multiple MOAs of UVR may limit applicability of current prediction models. - Abstract: The effects of chemical pollutants and environmental stressors, such as ultraviolet radiation (UVR), can interact when organisms are simultaneously exposed, resulting in higher (synergistic) or lower (antagonistic) multiple stressor effects than expected based on the effects of single stressors. Current understanding of interactive effects is limited due to a lack of mechanism-based multiple stressor studies. It has been hypothesized that effect interactions may generally occur if chemical and non-chemical stressors cause similar physiological effects in the organism. To test this hypothesis, we exposed the model green alga Chlamydomonas reinhardtii to combinations of UVR and single chemicals displaying modes of action (MOA) similar or dissimilar to the impact of UVR on photosynthesis. Stressor interactions were analyzed based on the independent action model. Effect interactions were found to depend on the MOA of the chemicals, and also on their concentrations, the exposure time and the measured endpoint. Indeed, only chemicals assumed to cause effects on photosynthesis similar to UVR showed interactions with UVR on photosynthetic yield: synergistic in case of Cd(II) and paraquat and antagonistic in case of diuron. No interaction on photosynthesis was observed for S-metolachlor, which acts dissimilarly to UVR. However, combined effects of S-metolachlor and UVR on algal reproduction were synergistic, highlighting the importance of considering additional MOA of UVR. Possible mechanisms of stressor effect interactions are

  9. Multiple stressor effects in Chlamydomonas reinhardtii – Toward understanding mechanisms of interaction between effects of ultraviolet radiation and chemical pollutants

    International Nuclear Information System (INIS)

    Korkaric, Muris; Behra, Renata; Fischer, Beat B.; Junghans, Marion; Eggen, Rik I.L.

    2015-01-01

    Highlights: • Systematic study of multiple stressor effects of UVR and chemicals in C. reinhardtii. • UVR and chemicals did not act independently on algal photosynthesis and reproduction. • Multiple stressor effects of UVR and chemicals depended on chemical MOA. • Synergistic effect interactions not limited to oxidative stress inducing chemicals. • Multiple MOAs of UVR may limit applicability of current prediction models. - Abstract: The effects of chemical pollutants and environmental stressors, such as ultraviolet radiation (UVR), can interact when organisms are simultaneously exposed, resulting in higher (synergistic) or lower (antagonistic) multiple stressor effects than expected based on the effects of single stressors. Current understanding of interactive effects is limited due to a lack of mechanism-based multiple stressor studies. It has been hypothesized that effect interactions may generally occur if chemical and non-chemical stressors cause similar physiological effects in the organism. To test this hypothesis, we exposed the model green alga Chlamydomonas reinhardtii to combinations of UVR and single chemicals displaying modes of action (MOA) similar or dissimilar to the impact of UVR on photosynthesis. Stressor interactions were analyzed based on the independent action model. Effect interactions were found to depend on the MOA of the chemicals, and also on their concentrations, the exposure time and the measured endpoint. Indeed, only chemicals assumed to cause effects on photosynthesis similar to UVR showed interactions with UVR on photosynthetic yield: synergistic in case of Cd(II) and paraquat and antagonistic in case of diuron. No interaction on photosynthesis was observed for S-metolachlor, which acts dissimilarly to UVR. However, combined effects of S-metolachlor and UVR on algal reproduction were synergistic, highlighting the importance of considering additional MOA of UVR. Possible mechanisms of stressor effect interactions are

  10. Apoptosis induced by low-intensity ultrasound in vitro: Alteration of protein profile and potential molecular mechanism

    Science.gov (United States)

    Feng, Yi; Wan, Mingxi

    2017-03-01

    To analyze the potential mechanism related to the apoptosis induced by low intensity focused ultrasound, comparative proteomic method was introduced in the study. After ultrasound irradiation (3.0 W/cm2, 1 minute, 6 hours incubation post-irradiation), the human SMMC-7721 hepatocarcinoma cells were stained by trypan blue to detect the morphologic changes, and then the percentage of early apoptosis were tested by the flow cytometry with double staining of FITC-labelled Annexin V/Propidium iodide. Two-dimensional SDS polyacrylamide gel electrophoresis was used to get the protein profile and some proteins differently expressed after ultrasound irradiation were identified by MALDI-TOF mass spectrometry. It's proved early apoptosis of cells were induced by low intentisy focused ultrasound. After ultrasound irradiation, the expressing characteristics of several proteins changed, in which protein p53 and heat shock proteins are associated with apoptosis initiation. It is suggested that the low-intensity ultrasound-induced apoptotic cancer therapy has the potential application via understanding its relevant molecular signaling and key proteins. Moreover, the comparative proteomic method is proved to be useful to supply information about the protein expression to analyze the metabolic processes related to bio-effects of biomedical ultrasound.

  11. How to make the clean development mechanism sustainable-The potential of rent extraction

    International Nuclear Information System (INIS)

    Muller, Adrian

    2007-01-01

    The clean development mechanism (CDM) should foster sustainable development and greenhouse gas emission reductions. The design of the CDM and first experience suggest that it may not achieve these goals. Developing countries hosting CDM projects may lose cheap emission reduction possibilities for their own future use, and sustainable development and technology transfer may not take place. On the other hand, the CDM has the potential to generate considerable rents if permit prices are high or costs low. To account for equity and distributional issues, a deliberate decision on how to distribute these rents could be taken and the potential failure of the CDM in meeting its goals calls for some further regulation. I suggest to combine these two issues and to extract the rents by a profit tax. Ideally, the tax revenues could contribute to national sustainable development strategies, to offset external costs imposed by CDM projects and to extract part of the resource rent they may generate. The international character of the CDM could offer a frame for internationally coordinated tax design. This would hedge against a potential race to the bottom

  12. Beat-to-beat variability of cardiac action potential duration: underlying mechanism and clinical implications.

    Science.gov (United States)

    Nánási, Péter P; Magyar, János; Varró, András; Ördög, Balázs

    2017-10-01

    Beat-to-beat variability of cardiac action potential duration (short-term variability, SV) is a common feature of various cardiac preparations, including the human heart. Although it is believed to be one of the best arrhythmia predictors, the underlying mechanisms are not fully understood at present. The magnitude of SV is basically determined by the intensity of cell-to-cell coupling in multicellular preparations and by the duration of the action potential (APD). To compensate for the APD-dependent nature of SV, the concept of relative SV (RSV) has been introduced by normalizing the changes of SV to the concomitant changes in APD. RSV is reduced by I Ca , I Kr , and I Ks while increased by I Na , suggesting that ion currents involved in the negative feedback regulation of APD tend to keep RSV at a low level. RSV is also influenced by intracellular calcium concentration and tissue redox potential. The clinical implications of APD variability is discussed in detail.

  13. CO2 emissions mitigation potential of solar home systems under clean development mechanism in India

    International Nuclear Information System (INIS)

    Purohit, Pallav

    2009-01-01

    The Government of India has taken several initiatives for promotion of solar energy systems in the country during the last two decades. A variety of policy measures have been adopted which include provision of financial and fiscal incentives to the potential users of solar energy systems however, only 0.4 million solar home systems (SHSs) have been installed so far that is far below their respective potential. One of the major barriers is the high costs of investments in these systems. The clean development mechanism (CDM) of the Kyoto Protocol provides industrialized (Annex-I) countries with an incentive to invest in emission reduction projects in developing (non-Annex-I) countries to achieve a reduction in carbon dioxide (CO 2 ) emissions at lowest cost that also promotes sustainable development in the host country. SHSs could be of interest under the CDM because they directly displace greenhouse gas (GHG) emissions while contributing to sustainable rural development, if developed correctly. In this study an attempt has been made to estimate the CO 2 mitigation potential of SHSs under CDM in India.

  14. On the Power Spectrum of Motor Unit Action Potential Trains Synchronized With Mechanical Vibration.

    Science.gov (United States)

    Romano, Maria; Fratini, Antonio; Gargiulo, Gaetano D; Cesarelli, Mario; Iuppariello, Luigi; Bifulco, Paolo

    2018-03-01

    This study provides a definitive analysis of the spectrum of a motor unit action potential train (MUAPT) elicited by mechanical vibratory stimulation via a detailed and concise mathematical formulation. Experimental studies demonstrated that MUAPs are not exactly synchronized with the vibratory stimulus but show a variable latency jitter, whose effects have not been investigated yet. Synchronized action potential train was represented as a quasi-periodic sequence of a given MU waveform. The latency jitter of action potentials was modeled as a Gaussian stochastic process, in accordance to the previous experimental studies. A mathematical expression for power spectrum of a synchronized MUAPT has been derived. The spectrum comprises a significant continuous component and discrete components at the vibratory frequency and its harmonics. Their relevance is correlated to the level of synchronization: the weaker the synchronization the more relevant is the continuous spectrum. Electromyography (EMG) rectification enhances the discrete components. The derived equations have general validity and well describe the power spectrum of actual EMG recordings during vibratory stimulation. Results are obtained by appropriately setting the level of synchronization and vibration frequency. This paper definitively clarifies the nature of changes in spectrum of raw EMG recordings from muscles undergoing vibratory stimulation. Results confirm the need of motion artifact filtering for raw EMG recordings during stimulation and strongly suggest to avoid EMG rectification that significantly alters the spectrum characteristics.

  15. The potential for gamma-emitting radionuclides to contribute to an understanding of erosion processes in South Africa

    Directory of Open Access Journals (Sweden)

    I. D. L. Foster

    2017-03-01

    Full Text Available Several research projects undertaken by the authors and others over the last 14 years have used fallout and geogenic radionuclides for understanding erosion processes and sediment yield dynamics in South Africa over the last 100–200 years as European settlers colonised the interior plains and plateaux of the country and imported new livestock and farming techniques to the region. These projects have used two fallout radionuclides (210Pb and 137Cs to date sediments accumulating in reservoirs, farm dams, wetlands, alluvial fans and floodouts and have used other fallout nuclides (7Be and long-lived geogenic radionuclides (e.g. 40K, 235U as part of a composite fingerprint exploring contemporary sediment sources and changes to sources through time. While successful in many parts of the world, applying these techniques in Southern Africa has posed a number of challenges often not encountered elsewhere. Here we explore some of the benefits and challenges in using gamma-emitting radionuclides, especially 137Cs, in these landscapes. Benefits include the potential for discriminating gully sidewall from topsoil sources, which has helped to identify contemporary gully systems as sediment conduits, rather than sources, and for providing a time-synchronous marker horizon in a range of sedimentary environments that has helped to develop robust chronologies. Challenges include the spatial variability in soil cover on steep rocky hillslopes, which is likely to challenge assumptions about the uniformity of initial fallout nuclide distribution, the paucity of stable (non-eroding sites in order to estimate atmospheric fallout inventories, and the limited success of 210Pb dating in some rapidly accumulating high altitude catchments where sediments often comprise significant amounts of sand and gravel. Despite these challenges we present evidence suggesting that the use of gamma-emitting radionuclides can make a significant contribution to our understanding of

  16. Influencing Mechanism of Potential Factors on Passengers’ Long-Distance Travel Mode Choices Based on Structural Equation Modeling

    Directory of Open Access Journals (Sweden)

    Yun Wang

    2017-10-01

    Full Text Available Understanding the public transportation users’ preferences to long-distance travel modes would contribute to reasonable developing policies and resource allocation. This paper aims to explore the influencing mechanism of potential factors on the long-distance travel mode choice. A survey was conducted to collect the data. The analysis of variance (ANOVA approach was applied to analyze the correlation relationship between potential factors and travel mode choice behavior. The results showed that, except gender, service demand for safety and departure time, all of the other factors significantly influenced the travel mode choice behavior. Specifically, passengers with higher education level and income level were more likely to choose high-speed railway (HSR and plane; passengers caring about travel expense were more likely to choose ordinary train, whereas plane and HSR may be chosen more by passengers caring more about comfort, punctuality and efficiency; the more passengers were satisfied with travel modes’ service performance, the more they would be likely to choose them; the most competitive distance ranges for coach, ordinary train, HSR and plane were below 500 km, 500–1000 km, 500–1500 km and over 1500 km, respectively. Besides, the structural equation modeling (SEM technique was applied to investigate the influencing mechanism of factors on the long-distance travel mode choice. The results revealed that travel distance was the most significant variable directly influencing passengers’ mode choices, followed by the service demand, performance evaluation, and personal attributes. Furthermore, personal attributes were verified to have an indirect effect on travel mode choice behavior by significantly affecting the service demand and performance evaluation.

  17. Adult and juvenile dermatomyositis: are the distinct clinical features explained by our current understanding of serological subgroups and pathogenic mechanisms?

    Science.gov (United States)

    2013-01-01

    Adult and juvenile dermatomyositis share the hallmark features of pathognomic skin rash and muscle inflammation, but are heterogeneous disorders with a range of additional disease features and complications. The frequency of important clinical features such as calcinosis, interstitial lung disease and malignancy varies markedly between adult and juvenile disease. These differences may reflect different disease triggers between children and adults, but whilst various viral and other environmental triggers have been implicated, results are so far conflicting. Myositis-specific autoantibodies can be detected in both adults and children with idiopathic inflammatory myopathies. They are associated with specific disease phenotypes and complications, and divide patients into clinically homogenous subgroups. Interestingly, whilst the same autoantibodies are found in both adults and children, the disease features remain different within autoantibody subgroups, particularly with regard to life-threatening disease associations, such as malignancy and rapidly progressive interstitial lung disease. Our understanding of the mechanisms that underlie these differences is limited by a lack of studies directly comparing adults and children. Dermatomyositis is an autoimmune disease, which is believed to develop as a result of an environmental trigger in a genetically predisposed individual. Age-specific host immune responses and muscle physiology may be additional complicating factors that have significant impact on disease presentation. Further study into this area may produce new insights into disease pathogenesis. PMID:23566358

  18. Copper-based opaque red glasses - Understanding the colouring mechanism of copper nanoparticles in archaeological glass samples

    Science.gov (United States)

    Drünert, F.; Blanz, M.; Pollok, K.; Pan, Z.; Wondraczek, L.; Möncke, D.

    2018-02-01

    Red opaque glasses of two different sites in central Germany, a medieval glassworks in Glashütten, Taunus Mountains, and an early modern glassworks in Wieda, Harz Mountains, were analysed with regard to their optical appearance. By scanning electron microscopy and X-ray diffraction, metallic copper nanoparticles were identified as a conspicuous constituent in these glasses. In addition, similar opaque red glasses were reproduced in the laboratory in order to better understand the manufacturing process. Detailed analysis of the optical scattering was conducted in order to evaluate the role of Cu0 nanoparticles in the colouring mechanism relative to other possible reasons of colouration. We find clear differences between the possible contributions of Cu2O (cuprite) particles and metallic copper (Cu0) nanoparticles. Through simulated backscattering spectra we were able to calculate an average copper particle radius in the archaeological glass samples resulting in a value of up to 95 nm, which matches well the results of SEM investigation (minimum 65 nm). Using the methods we applied in this study, it becomes possible to reconstruct various processing conditions as they were applied in medieval manufacture of these particular materials.

  19. Toward a better understanding of the mechanisms of symbiosis: a comprehensive proteome map of a nascent insect symbiont

    Directory of Open Access Journals (Sweden)

    François Renoz

    2017-05-01

    Full Text Available Symbiotic bacteria are common in insects and can affect various aspects of their hosts’ biology. Although the effects of insect symbionts have been clarified for various insect symbiosis models, due to the difficulty of cultivating them in vitro, there is still limited knowledge available on the molecular features that drive symbiosis. Serratia symbiotica is one of the most common symbionts found in aphids. The recent findings of free-living strains that are considered as nascent partners of aphids provide the opportunity to examine the molecular mechanisms that a symbiont can deploy at the early stages of the symbiosis (i.e., symbiotic factors. In this work, a proteomic approach was used to establish a comprehensive proteome map of the free-living S. symbiotica strain CWBI-2.3T. Most of the 720 proteins identified are related to housekeeping or primary metabolism. Of these, 76 were identified as candidate proteins possibly promoting host colonization. Our results provide strong evidence that S. symbiotica CWBI-2.3T is well-armed for invading insect host tissues, and suggest that certain molecular features usually harbored by pathogenic bacteria are no longer present. This comprehensive proteome map provides a series of candidate genes for further studies to understand the molecular cross-talk between insects and symbiotic bacteria.

  20. Understanding the mechanism of toxicity of carbon nanoparticles in humans in the new millennium: A systemic review

    Science.gov (United States)

    Sharma, Mukesh

    2010-01-01

    Manmade nanoparticles range from the well-established multi-ton production of carbon black and fumed silica for applications in plastic fillers and car tyres to microgram quantities of fluorescent quantum dots used as markers in biological imaging. While benefits of nanotechnology are widely publicized, the discussion of the potential effects of their widespread use in the consumer and industrial products are just beginning to emerge. Acceptance of nanoparticle toxicity led to wide acceptance of the fact that nanotoxicology, as a scientific discipline shall be quite different from occupational hygiene in approach and context. Understanding the toxicity of nanomaterials and nano-enabled products is important for human and environmental health and safety as well as public acceptance. Assessing the state of knowledge about nanotoxicology is an important step in promoting comprehensive understanding of the health and environmental implications of these new materials. Very limited data exist for health effects secondary to inhalation of very fine respirable particles in the occupational environment. Nanomaterials may have effects on health due to their size, surface, shape, charge, or other factors, which are not directly predictable from mass concentration measurements. Numerous epidemiological studies have associated exposure to small particles such as combustion-generated fine particles with lung cancer, heart disease, asthma and/or increased mortality. The omnipresence of nanoparticles shifts focus of research toward efforts to mitigate the health effects of nanoparticles. Newer health assessment methods and newer techniques need to be developed for diagnosing sub-optimal health in populations exposed to carbon nanoparticles. PMID:20808660

  1. Docking based 3d-QSAR studies applied at the BRAF inhibitors to understand the binding mechanism

    International Nuclear Information System (INIS)

    Mahmood, U.; Haq, Z.U.

    2011-01-01

    BRAF is a great therapeutic target in a wide variety of human cancers. It is the member of Ras Activating Factor (RAF) family of serine/throenine kinase. The mutated form of the BRAF has diverted all the attention towards itself because of increase severity and elevated kinase activity. The RAF signal transduction cascade is a conserved protein pathway that is involved in cell cycle progression and apoptosis. The ERK regulates phosphorylation of different proteins either in cytosol or in nucleus but disorders in ERK signaling pathway cause mutation in BRAF. This cascade in these cells may provide selection of mutated BRAF in which valine is substituted with glutamatic acid at position 600. This mutation occurs in activation loop. A number of inhibitors reported to target different members of RAF, some of them have potential to target the BRAF as well. Major reason for failure of previously reported inhibitors was due to the highly conserved sequence and confirmation of catalytic cleft which is always a center of consideration for binding of inhibitors to suppress the kinase activity. This is the first attempt to study and understand the BARF inhibitors - protein interactions in detail by utilizing 3D-QSAR and molecular docking techniques. Most reliable techniques of 3D QSAR i.e Comparative Molecular Field Analysis (CoMFA) and Comparative Molecular Similarity Indices Analysis (CoMSIA) were applied for three different data sets. The data sets selected for better evaluation of BRAF inhibitors belongs to 2, 6-Disubstituted Pyrazine, Pyridoimidazolones and its derivatives. Our models would offer help to better understand the structure-activity relationships that exist for these classes of compounds and also facilitate the design of novel inhibitors with good chemical diversity. (Author)

  2. Potential trajectories of the upcoming forest trading mechanism in Pará State, Brazilian Amazon.

    Directory of Open Access Journals (Sweden)

    Brenda Brito

    Full Text Available In 2012, the Brazilian government revised the federal Forest Code that governs the use of forest resources on rural properties. The revisions included a forest trading mechanism whereby landowners who deforested more than what is legally allowed before 2008 could absolve their deforestation "debts" by purchasing Environmental Reserve Quotas (CRA from landowners who conserved more forest than legally required. CRA holds promise as a tool to complement command-and-control initiatives to reduce deforestation and incentivize restoration. However, the success of this instrument depends on how its implementation is governed. This study builds on a few recent assessments of the potential of the CRA in Brazil-but that are focused on biophysical potential-by assessing how a few key implementation decisions may influence the CRA market development. Specifically, this study estimates how decisions on who can participate will likely influence the potential forest surplus and forest debt for the CRA market, and takes into account governance characteristics relevant to the State of Pará, eastern Amazonia. In particular, the study evaluates the effects in the CRA market eligibility after simulating a validation of properties in the environmental rural registry (CAR and assessing different scenarios surrounding land tenure status of properties. Results show how regulatory decisions on CRA market eligibility will determine the extent to which CRA will serve as a tool to support forest conservation or as a low-cost path to help illegal deforesters to comply with legislation, but with limited additional environmental benefits. The study reviews regulatory options that would reduce the risk of forest oversupply, and thereby increase the additionality of the areas eligible for CRA. Overall, the study demonstrates the importance of including governance as well as biophysical characteristics in assessing the potential of forest trading tools to deliver additional

  3. Potential trajectories of the upcoming forest trading mechanism in Pará State, Brazilian Amazon.

    Science.gov (United States)

    Brito, Brenda

    2017-01-01

    In 2012, the Brazilian government revised the federal Forest Code that governs the use of forest resources on rural properties. The revisions included a forest trading mechanism whereby landowners who deforested more than what is legally allowed before 2008 could absolve their deforestation "debts" by purchasing Environmental Reserve Quotas (CRA) from landowners who conserved more forest than legally required. CRA holds promise as a tool to complement command-and-control initiatives to reduce deforestation and incentivize restoration. However, the success of this instrument depends on how its implementation is governed. This study builds on a few recent assessments of the potential of the CRA in Brazil-but that are focused on biophysical potential-by assessing how a few key implementation decisions may influence the CRA market development. Specifically, this study estimates how decisions on who can participate will likely influence the potential forest surplus and forest debt for the CRA market, and takes into account governance characteristics relevant to the State of Pará, eastern Amazonia. In particular, the study evaluates the effects in the CRA market eligibility after simulating a validation of properties in the environmental rural registry (CAR) and assessing different scenarios surrounding land tenure status of properties. Results show how regulatory decisions on CRA market eligibility will determine the extent to which CRA will serve as a tool to support forest conservation or as a low-cost path to help illegal deforesters to comply with legislation, but with limited additional environmental benefits. The study reviews regulatory options that would reduce the risk of forest oversupply, and thereby increase the additionality of the areas eligible for CRA. Overall, the study demonstrates the importance of including governance as well as biophysical characteristics in assessing the potential of forest trading tools to deliver additional environmental

  4. From genomes to metabolomes: Understanding mechanisms of symbiosis and cell-cell signaling using the archaeal system Ignicoccus-Nanoarchaeum

    Energy Technology Data Exchange (ETDEWEB)

    Podar, Mircea [Univ. of Tennessee, Knoxville, TN (United States). Biosciences Division; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hettich, Robert [Univ. of Tennessee, Knoxville, TN (United States). Biosciences Division; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Copie, Valerie [Montana State Univ., Bozeman, MT (United States). Dept. of Chemistry and Biochemistry; Bothner, Brian [Montana State Univ., Bozeman, MT (United States). Dept. of Chemistry and Biochemistry

    2016-12-16

    The main objective of this project was to use symbiotic Nanoarchaeaota, a group of thermophilic Archaea that are obligate symbionts/parasites on other Archaea, to develop an integrated multi-omic approach to study inter-species interactions as well as to understand fundamental mechanism that enable such relationships. As part of this grant we have achieved a number of important milestone on both technical and scientific levels. On the technical side, we developed immunofluorescence labeling and tracking methods to follow Nanoarchaeota in cultures and in environmental samples, we applied such methods in conjunction with flow cytometry to quantify and isolate uncultured representatives from the environment and characterized them by single cell genomics. On the proteomics side, we developed a more efficient and sensitive method to recover and semi-quantitatively measure membrane proteins, while achieving high total cellular proteome coverage (70-80% of the predicted proteome). Metabolomic analyses used complementary NMR and LC/GC mass spectrometry and led to the identification of novel lipids in these organisms as well as quantification of some of the major metabolites. Importantly, using several informatics approaches we were also able to integrate the transcriptomic, proteomic and metabolomic datasets, revealing aspects of the interspecies interaction that were not evident in the single omic analyses (manuscript in review). On the science side we determined that N. equitans and I. hospitalis are metabolically coupled and that N. equitans is strictly dependent on its host both for metabolic precursors and energetic needs. The actual mechanism by which small molecules move across the cell membrane remains unknown. The Ignicoccus host responds to the metabolic and energetic burned by upregulating of key primary metabolism steps and ATP synthesis. The two species have co-evolved, aspect that we determined by comparative genomics with other species of Ignicoccus

  5. Understanding the role of keratins 8 and 18 in neoplastic potential of breast cancer derived cell lines.

    Directory of Open Access Journals (Sweden)

    Sapna V Iyer

    Full Text Available BACKGROUND: Breast cancer is a complex disease which cannot be defined merely by clinical parameters like lymph node involvement and histological grade, or by routinely used biomarkers like estrogen receptor (ER, progesterone receptor (PGR and epidermal growth factor receptor 2 (HER2 in diagnosis and prognosis. Breast cancer originates from the epithelial cells. Keratins (K are cytoplasmic intermediate filament proteins of epithelial cells and changes in the expression pattern of keratins have been seen during malignant transformation in the breast. Expression of the K8/18 pair is seen in the luminal cells of the breast epithelium, and its role in prognostication of breast cancer is not well understood. METHODOLOGY/PRINCIPAL FINDINGS: In this study, we have modulated K8 expression to understand the role of the K8/18 pair in three different breast epithelium derived cell lines: non-transformed MCF10A, transformed but poorly invasive MDA MB 468 and highly invasive MDA MB 435. The up-regulation of K8 in the invasive MDA MB 435 cell line resulted in a significant decrease in proliferation, motility, in-vitro invasion, tumor volume and lung metastasis. The down-regulation of K8 in MDA MB 468 resulted in a significant increase in transformation potential, motility and invasion in-vitro, while MCF10A did not show any changes in cell transformation assays. CONCLUSIONS/SIGNIFICANCE: These results indicate the role of K8/18 in modulating invasion in breast cancer -its presence correlating with less invasive phenotype and absence correlating with highly invasive, dedifferentiated phenotype. These data may have important implications for prognostication of breast cancer.

  6. Parenting practices as potential mechanisms for child adjustment following mass trauma.

    Science.gov (United States)

    Gewirtz, Abigail; Forgatch, Marion; Wieling, Elizabeth

    2008-04-01

    Trauma research has identified a link between parental adjustment and children's functioning and the sometimes ensuing intergenerational impact of traumatic events. The effects of traumatic events on children have been demonstrated to be mediated through their impact on children's parents. However, until now, little consideration has been given to the separate and more proximal mechanism of parenting practices as potential mediators between children's adjustment and traumatic events. To shed some light in this arena, we review literature on trauma, adversity, and resilience, and discuss how parenting practices may mediate trauma and adverse environmental contexts. Using a social interaction learning perspective (Forgatch & Knutson, 2002; Patterson, 2005), we propose a prevention research framework to examine the role that parenting practices may play in influencing children's adjustment in the wake of trauma exposure. The article concludes by providing a specific model and role for evidence-based parenting interventions for children exposed to mass trauma.

  7. Reproductive endocrine-disrupting effects of triclosan: Population exposure, present evidence and potential mechanisms.

    Science.gov (United States)

    Wang, Cai-Feng; Tian, Ying

    2015-11-01

    Triclosan has been used as a broad-spectrum antibacterial agent for over 40 years worldwide. Increasing reports indicate frequent detection and broad exposure to triclosan in the natural environment and the human body. Current laboratory studies in various species provide strong evidence for its disrupting effects on the endocrine system, especially reproductive hormones. Multiple modes of action have been suggested, including disrupting hormone metabolism, displacing hormones from hormone receptors and disrupting steroidogenic enzyme activity. Although epidemiological studies on its effects in humans are mostly negative but conflicting, which is typical of much of the early evidence on the toxicity of EDCs, overall, the evidence suggests that triclosan is an EDC. This article reviews human exposure to triclosan, describes the current evidence regarding its reproductive endocrine-disrupting effects, and discusses potential mechanisms to provide insights for further study on its endocrine-disrupting effects in humans. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Inhibition of enzyme activity by nanomaterials: potential mechanisms and implications for nanotoxicity testing.

    Science.gov (United States)

    Maccormack, Tyson J; Clark, Rhett J; Dang, Michael K M; Ma, Guibin; Kelly, Joel A; Veinot, Jonathan G C; Goss, Greg G

    2012-08-01

    The objective of this study was to investigate whether nanoparticle-exposure affects enzyme function and to determine the mechanisms responsible. Silicon, Au, and CdSe nanoparticles were synthesized in house and their physicochemical properties were characterized. The activity of purified lactate dehydrogenase (LDH) was inhibited or abolished by all nanoparticles tested. Inhibition was dependent upon particle core and surface-functional group composition. Inhibition of LDH was absent in crude tissue homogenates, in the presence of albumin, and at the isoelectric point of the protein, indicating that nanoparticles bind non-specifically to abundant proteins via a charge interaction. Circular dichroism spectroscopy suggests that the structure of LDH may be altered by nanoparticles in a manner different from that of bulk controls. We present new data on the specific physicochemical properties of nanoparticles that may lead to bioactivity and highlight a number of potentially serious problems with common nanotoxicity testing methods.

  9. Ti-Ag-Pd alloy with good mechanical properties and high potential for biological applications

    Science.gov (United States)

    Zadorozhnyy, V. Yu.; Shi, X.; Gorshenkov, M. V.; Kozak, D. S.; Wada, T.; Louzguine-Luzgin, D. V.; Inoue, A.; Kato, H.

    2016-04-01

    Ti-based alloys containing Ag were produced by tilt-casting method and their properties were studied. Even in its as-cast state, Ti94Ag3Pd3 showed relatively high tensile properties, good electrochemical behavior, and good biocompatibility. The relatively good mechanical properties of the as-cast α-Ti-type Ti94Ag3Pd3 alloy (tensile strength up to 850 MPa and elongation of ~10%) can be explained by its severely deformed, fine crystalline structure. The high biocompatibility of Ti94Ag3Pd3 can be explained by the Ag-Pd interaction, which inhibits the release of Ag ions from the surface. Ag, in combination with Pd has no toxic effects and demonstrates useful antimicrobial properties. The Ti94Ag3Pd3 alloy shows a good potential to be applied as a biomedical implant alloy.

  10. Smoking and increased Alzheimer’s disease risk: A review of potential mechanisms

    Science.gov (United States)

    Durazzo, Timothy C.; Mattsson, Niklas; Weiner, Michael W.

    2014-01-01

    Background Cigarette smoking has been linked with both increased and decreased risk for Alzheimer’s disease (AD). This is relevant for the US military because the prevalence of smoking in the military is approximately 11% higher than in civilians. Methods Systematic review of published studies on the association between smoking and increased risk for AD, and preclinical and human literature on the relationships between smoking, nicotine exposure and AD-related neuropathology. Original data from comparisons of smoking and never-smoking cognitively normal elders on in vivo amyloid imaging are also presented. Results Overall, the literature indicates that former/active smoking is related to a significantly increased risk for AD. Cigarette smoke/smoking is associated with AD neuropathology in preclinical models and humans. Smoking-related cerebral oxidative stress is a potential mechanism promoting AD pathophysiology and increased risk for AD. Conclusions A reduction in the incidence of smoking will likely reduce the future prevalence of AD. PMID:24924665

  11. Potential protective mechanisms of aryl hydrocarbon receptor (AHR) signaling in benign prostatic hyperplasia

    Science.gov (United States)

    Mehta, Vatsal; Vezina, Chad M.

    2011-01-01

    The aryl hydrocarbon receptor (AHR) is an evolutionarily conserved ligand activated transcription factor best known for its role in mediating toxic responses to dioxin-like environmental contaminants. However, AHR signaling has also emerged as an active participant in processes of normal development and disease progression. Here, we review the role of AHR signaling in prostate development and disease processes, with a particular emphasis on benign prostatic hyperplasia (BPH). Inappropriate AHR activation has recently been associated with a decreased risk of symptomatic BPH in humans and has been shown to impair prostate development and disrupt endocrine signaling in rodents. We highlight known physiological responses to AHR activation in prostate and other tissues and discuss potential mechanisms by which it may act in adult human prostate to protect against symptomatic BPH. PMID:21684673

  12. Potential mechanisms underlying anxiety and depression in Parkinson's disease: consequences of L-DOPA treatment

    Science.gov (United States)

    Eskow Jaunarajs, Karen L.; Angoa-Perez, Mariana; Kuhn, Donald M.; Bishop, Christopher

    2010-01-01

    Though the most recognizable symptoms of Parkinson's disease (PD) are motor-related, many patients also suffer from debilitating affective symptoms that deleteriously influence quality of life. Dopamine (DA) loss is likely involved in the onset of depression and anxiety in PD. However, these symptoms are not reliably improved by DA replacement therapy with L-3,4-dihydroxyphenylalanine (L-DOPA). In fact, preclinical and clinical evidence suggests that L-DOPA treatment may worsen affect. Though the neurobiological mechanisms remain unclear, recent research contends that L-DOPA further perturbs the function of the norepinephrine and serotonin systems, already affected by PD pathology, which have been intimately linked to the development and expression of anxiety and depression. As such, this review provides an overview of the clinical characteristics of affective disorders in PD, examines the utility of animal models for the study of anxiety and depression in PD, and finally, discusses potential mechanisms by which DA loss and subsequent L-DOPA therapy influence monoamine function and concomitant affective symptoms. PMID:20615430

  13. Benefits of Nut Consumption on Insulin Resistance and Cardiovascular Risk Factors: Multiple Potential Mechanisms of Actions

    Directory of Open Access Journals (Sweden)

    Yoona Kim

    2017-11-01

    Full Text Available Epidemiological and clinical studies have indicated that nut consumption could be a healthy dietary strategy to prevent and treat type 2 diabetes (T2DM and related cardiovascular disease (CVD. The objective of this review is to examine the potential mechanisms of action of nuts addressing effects on glycemic control, weight management, energy balance, appetite, gut microbiota modification, lipid metabolism, oxidative stress, inflammation, endothelial function and blood pressure with a focus on data from both animal and human studies. The favourable effects of nuts could be explained by the unique nutrient composition and bioactive compounds in nuts. Unsaturated fatty acids (monounsaturated fatty acids and polyunsaturated fatty acids present in nuts may play a role in glucose control and appetite suppression. Fiber and polyphenols in nuts may also have an anti-diabetic effect by altering gut microbiota. Nuts lower serum cholesterol by reduced cholesterol absorption, inhibition of HMG-CoA reductase and increased bile acid production by stimulation of 7-α hydroxylase. Arginine and magnesium improve inflammation, oxidative stress, endothelial function and blood pressure. In conclusion, nuts contain compounds that favourably influence glucose homeostasis, weight control and vascular health. Further investigations are required to identify the most important mechanisms by which nuts decrease the risk of T2DM and CVD.

  14. Potentially dangerous fih of the Paraiba Estuary: Identifiation and envenomation mechanisms

    Directory of Open Access Journals (Sweden)

    Anderson Kelvin Saraiva Macêdo

    2017-11-01

    Full Text Available Objective: To present venomous and poisonous fish species in the Paraiba Estuary, Paraiba State, Brazil, with a description of the envenomation mechanisms and characteristics of the toxins. Methods: Fishes were caught by beach seine in the dry and rainy season (November 2013 and June 2014 and bimonthly between May 2016 and March 2017. Results: Eight potentially dangerous species belonging to the families Batrachoididae, Ariidae and Tetraodontidae were identified. The representatives of the former two families, toadfish and catfish, respectively had specific venom inoculating apparatuses that could penetrate tissues, releasing toxins that caused injuries mainly to fishermen. The family Tetraodontidae had poisonous species, once the pufferfish could accumulate biotoxins (especially tetrodotoxin, which is a neurotoxin produced by bacteria. Despite being toxic for consumption, these fish were often consumed by fishermen and their families. Conclusions: The present study is the first record of venomous and poisonous species in the Paraiba Estuary and contributes to the knowledge of the identification of the species and the mechanisms that cause severe envenomation and even deaths in artisanal fishing communities. Such knowledge is fundamental to future campaigns aimed at the prevention of injuries involving fish in the region and in other estuarine environments, where such fishes are common.

  15. The Anticonvulsant Effects of Ketogenic Diet on Epileptic Seizures and Potential Mechanisms.

    Science.gov (United States)

    Zhang, Yifan; Xu, Jingwei; Zhang, Kun; Yang, Wei; Li, Bingjin

    2018-01-01

    Epilepsy is a syndrome of brain dysfunction induced by the aberrant excitability of certain neurons. Despite advances in surgical technique and anti-epileptic drug in recent years, recurrent epileptic seizures remain intractable and lead to a serious morbidity in the world. The ketogenic diet refers to a high-fat, low-carbohydrate and adequate-protein diet. Currently, its beneficial effects on epileptic seizure reduction have been well established. However, the detailed mechanisms underlying the anti-epileptic effects of ketogenic diet are still poorly understood. In this article, the possible roles of ketogenic diet on epilepsy were discussed. Data was obtained from the websites including Web of Science, Medline, Pubmed, Scopus, based on these keywords: "Ketogenic diet" and "epilepsy". As shown in both clinical and basic studies, the therapeutic effects of ketogenic diet might involve neuronal metabolism, neurotransmitter function, neuronal membrane potential and neuron protection against ROS. In this review, we systematically reviewed the effects and possible mechanisms of ketogenic diet on epilepsy, which may optimize the therapeutic strategies against epilepsy. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  16. Phytoremediation potential of the novel atrazine tolerant Lolium multiflorum and studies on the mechanisms involved

    Energy Technology Data Exchange (ETDEWEB)

    Merini, Luciano J. [Catedra de Microbiologia Industrial y Biotecnologia, Universidad de Buenos Aires (Argentina); Bobillo, Cecilia [Servicio de Huellas Digitales Geneticas, Facultad de Farmacia y Bioquimica, Microbiologia Industrial y Biotecnologia, Universidad de Buenos Aires, Junin 956, BS As (Argentina); Cuadrado, Virginia [Catedra de Microbiologia Industrial y Biotecnologia, Universidad de Buenos Aires (Argentina); Corach, Daniel [Servicio de Huellas Digitales Geneticas, Facultad de Farmacia y Bioquimica, Microbiologia Industrial y Biotecnologia, Universidad de Buenos Aires, Junin 956, BS As (Argentina); Giulietti, Ana M., E-mail: agiule@ffyb.uba.a [Catedra de Microbiologia Industrial y Biotecnologia, Universidad de Buenos Aires (Argentina)

    2009-11-15

    Atrazine impact on human health and the environment have been extensively studied. Phytoremediation emerged as a low cost, environmental friendly biotechnological solution for atrazine pollution in soil and water. In vitro atrazine tolerance assays were performed and Lolium multiflorum was found as a novel tolerant species, able to germinate and grow in the presence of 1 mg kg{sup -1} of the herbicide. L. multiflorum presented 20% higher atrazine removal capacity than the natural attenuation, with high initial degradation rate in microcosms. The mechanisms involved in atrazine tolerance such as mutation in psbA gene, enzymatic detoxification via P{sub 450} or chemical hydrolysis through benzoxazinones were evaluated. It was demonstrated that atrazine tolerance is conferred by enhanced enzymatic detoxification via P{sub 450}. Due to its atrazine degradation capacity in soil and its agronomical properties, L. multiflorum is a candidate for designing phytoremediation strategies for atrazine contaminated agricultural soils, especially those involving run-off avoiding. - Finding of a novel atrazine-tolerant species, as a potential candidate for phytoremediating herbicide-contaminated agriculture soils and elucidation of the mechanisms involved in tolerance.

  17. Phytoremediation potential of the novel atrazine tolerant Lolium multiflorum and studies on the mechanisms involved

    International Nuclear Information System (INIS)

    Merini, Luciano J.; Bobillo, Cecilia; Cuadrado, Virginia; Corach, Daniel; Giulietti, Ana M.

    2009-01-01

    Atrazine impact on human health and the environment have been extensively studied. Phytoremediation emerged as a low cost, environmental friendly biotechnological solution for atrazine pollution in soil and water. In vitro atrazine tolerance assays were performed and Lolium multiflorum was found as a novel tolerant species, able to germinate and grow in the presence of 1 mg kg -1 of the herbicide. L. multiflorum presented 20% higher atrazine removal capacity than the natural attenuation, with high initial degradation rate in microcosms. The mechanisms involved in atrazine tolerance such as mutation in psbA gene, enzymatic detoxification via P 450 or chemical hydrolysis through benzoxazinones were evaluated. It was demonstrated that atrazine tolerance is conferred by enhanced enzymatic detoxification via P 450 . Due to its atrazine degradation capacity in soil and its agronomical properties, L. multiflorum is a candidate for designing phytoremediation strategies for atrazine contaminated agricultural soils, especially those involving run-off avoiding. - Finding of a novel atrazine-tolerant species, as a potential candidate for phytoremediating herbicide-contaminated agriculture soils and elucidation of the mechanisms involved in tolerance.

  18. Mechanism of Bacterial Inactivation by (+)-Limonene and Its Potential Use in Food Preservation Combined Processes

    Science.gov (United States)

    Espina, Laura; Gelaw, Tilahun K.; de Lamo-Castellví, Sílvia; Pagán, Rafael; García-Gonzalo, Diego

    2013-01-01

    This work explores the bactericidal effect of (+)-limonene, the major constituent of citrus fruits' essential oils, against E. coli. The degree of E. coli BJ4 inactivation achieved by (+)-limonene was influenced by the pH of the treatment medium, being more bactericidal at pH 4.0 than at pH 7.0. Deletion of rpoS and exposure to a sub-lethal heat or an acid shock did not modify E. coli BJ4 resistance to (+)-limonene. However, exposure to a sub-lethal cold shock decreased its resistance to (+)-limonene. Although no sub-lethal injury was detected in the cell envelopes after exposure to (+)-limonene by the selective-plating technique, the uptake of propidium iodide by inactivated E. coli BJ4 cells pointed out these structures as important targets in the mechanism of action. Attenuated Total Reflectance Infrared Microspectroscopy (ATR-IRMS) allowed identification of altered E. coli BJ4 structures after (+)-limonene treatments as a function of the treatment pH: β-sheet proteins at pH 4.0 and phosphodiester bonds at pH 7.0. The increased sensitivity to (+)-limonene observed at pH 4.0 in an E. coli MC4100 lptD4213 mutant with an increased outer membrane permeability along with the identification of altered β-sheet proteins by ATR-IRMS indicated the importance of this structure in the mechanism of action of (+)-limonene. The study of mechanism of inactivation by (+)-limonene led to the design of a synergistic combined process with heat for the inactivation of the pathogen E. coli O157:H7 in fruit juices. These results show the potential of (+)-limonene in food preservation, either acting alone or in combination with lethal heat treatments. PMID:23424676

  19. Mechanism of bacterial inactivation by (+-limonene and its potential use in food preservation combined processes.

    Directory of Open Access Journals (Sweden)

    Laura Espina

    Full Text Available This work explores the bactericidal effect of (+-limonene, the major constituent of citrus fruits' essential oils, against E. coli. The degree of E. coli BJ4 inactivation achieved by (+-limonene was influenced by the pH of the treatment medium, being more bactericidal at pH 4.0 than at pH 7.0. Deletion of rpoS and exposure to a sub-lethal heat or an acid shock did not modify E. coli BJ4 resistance to (+-limonene. However, exposure to a sub-lethal cold shock decreased its resistance to (+-limonene. Although no sub-lethal injury was detected in the cell envelopes after exposure to (+-limonene by the selective-plating technique, the uptake of propidium iodide by inactivated E. coli BJ4 cells pointed out these structures as important targets in the mechanism of action. Attenuated Total Reflectance Infrared Microspectroscopy (ATR-IRMS allowed identification of altered E. coli BJ4 structures after (+-limonene treatments as a function of the treatment pH: β-sheet proteins at pH 4.0 and phosphodiester bonds at pH 7.0. The increased sensitivity to (+-limonene observed at pH 4.0 in an E. coli MC4100 lptD4213 mutant with an increased outer membrane permeability along with the identification of altered β-sheet proteins by ATR-IRMS indicated the importance of this structure in the mechanism of action of (+-limonene. The study of mechanism of inactivation by (+-limonene led to the design of a synergistic combined process with heat for the inactivation of the pathogen E. coli O157:H7 in fruit juices. These results show the potential of (+-limonene in food preservation, either acting alone or in combination with lethal heat treatments.

  20. Formation mechanism of self-potential at ISL-amenable interlayer oxidation zone sandstone-type uranium deposit and the simulation and application of self-potential anomalies

    International Nuclear Information System (INIS)

    Tang Hongzhi; Liu Qingcheng; Su Zhaofeng; Gong Yuling

    2006-01-01

    Based on the analysis of geochemical characteristics and metallogenic physico-chemical conditions of ISL-amenable sandstone-type uranium deposits, the formation mechanism of self-potential field is discussed, a mathematic calculation model has been set up, and the simulation calculation has been performed for self-potential anomalies above uranium ore bodies of ordinary form, features of survey curve are analysed and methods for correcting topography at self-potential anomalies are discussed, and a simulation curve of self-potential in the area of slope topography has been presented. Finally, the availability of the method is demonstrated by an example. (authors)

  1. Recent advances in understanding the characteristics of seismogenic intraplate deformation in Australia, and the potential for using global analogues

    Science.gov (United States)

    Clark, Dan; McPherson, Andrew

    2017-04-01

    relation to individual faults in non-cratonic and extended superdomains. However, large earthquake recurrence and slip are demonstrably not evenly distributed in time. Within the limitations of the sparse paleoseismological data, temporal clustering of large events appears to be a common (perhaps ubiquitous?) characteristic. Over the last few decades, permanent and campaign GPS studies have failed to detect a tectonic deformation signal from which a strain budget could be calculated. Recent studies have used these observations, amongst others, to propose an orders of magnitude difference in the timescales of strain accumulation and seismogenic strain release in intraplate environments - i.e. clusters of large events deplete long-lived pools of lithospheric strain. The recognition of a relationship between crustal type/lithospheric thickness and seismogenic potential in Australia provides a framework for assessing whether ergodic substitution (i.e. global analogue studies) might be warranted as a tool to better understand intraplate seismicity worldwide. Further research is required to assess how variation in crustal stress regime may influence faulting characteristics within different superdomains.

  2. Developmental song learning as a model to understand neural mechanisms that limit and promote the ability to learn.

    Science.gov (United States)

    London, Sarah E

    2017-11-20

    Songbirds famously learn their vocalizations. Some species can learn continuously, others seasonally, and still others just once. The zebra finch (Taeniopygia guttata) learns to sing during a single developmental "Critical Period," a restricted phase during which a specific experience has profound and permanent effects on brain function and behavioral patterns. The zebra finch can therefore provide fundamental insight into features that promote and limit the ability to acquire complex learned behaviors. For example, what properties permit the brain to come "on-line" for learning? How does experience become encoded to prevent future learning? What features define the brain in receptive compared to closed learning states? This piece will focus on epigenomic, genomic, and molecular levels of analysis that operate on the timescales of development and complex behavioral learning. Existing data will be discussed as they relate to Critical Period learning, and strategies for future studies to more directly address these questions will be considered. Birdsong learning is a powerful model for advancing knowledge of the biological intersections of maturation and experience. Lessons from its study not only have implications for understanding developmental song learning, but also broader questions of learning potential and the enduring effects of early life experience on neural systems and behavior. Copyright © 2017. Published by Elsevier B.V.

  3. Sex hormones and adult hippocampal neurogenesis: Regulation, implications, and potential mechanisms.

    Science.gov (United States)

    Mahmoud, Rand; Wainwright, Steven R; Galea, Liisa A M

    2016-04-01

    Neurogenesis within the adult hippocampus is modulated by endogenous and exogenous factors. Here, we review the role of sex hormones in the regulation of adult hippocampal neurogenesis in males and females. The review is framed around the potential functional implications of sex hormone regulation of adult hippocampal neurogenesis, with a focus on cognitive function and mood regulation, which may be related to sex differences in incidence and severity of dementia and depression. We present findings from preclinical studies of endogenous fluctuations in sex hormones relating to reproductive function and ageing, and from studies of exogenous hormone manipulations. In addition, we discuss the modulating roles of sex, age, and reproductive history on the relationship between sex hormones and neurogenesis. Because sex hormones have diverse targets in the central nervous system, we overview potential mechanisms through which sex hormones may influence hippocampal neurogenesis. Lastly, we advocate for a more systematic consideration of sex and sex hormones in studying the functional implications of adult hippocampal neurogenesis. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. A look at the possible mechanism and potential of magneto therapy.

    Science.gov (United States)

    Jacobson, J I

    1991-03-07

    A testable theoretical model for the mechanism of magneto-therapy is presented. The theory delineated is the equation mc2 = Bvl coulomb which sets in dual resonance gravitational and electromagnetic potentials. This proposed unification of Einstein's gravity and Maxwell's electromagnetism is designated Jacobson's resonance and is a general expression of Zeeman and cyclotron resonance. The application of this theory involves the utilization of exogenously sourced very weak magnetic fields on the order of magnitude 10(-8) gauss to reorient the atomic crystal lattice structures of genomic magnetic domains. Examples of genomic magnetic domains are homeoboxes and oncogenes and associated structures like peptide hormone trophic factors. Various phenomena are also analyzed in terms of how they may relate to biological systems such as solitons, phonons, cyclotron resonance, the piezoelectric effect, the fractional quantum Hall effect, string theory, and biologically closed electric circuits. The potential of magneto-therapy in the treatment of various genomic and associated disorders is explored. The ultimate question "Can an oncogene be electromagnetically induced into becoming a structurally homologous normal gene?" is posed.

  5. Physical activity and telomere length: Impact of aging and potential mechanisms of action.

    Science.gov (United States)

    Arsenis, Nicole C; You, Tongjian; Ogawa, Elisa F; Tinsley, Grant M; Zuo, Li

    2017-07-04

    Telomeres protect the integrity of information-carrying DNA by serving as caps on the terminal portions of chromosomes. Telomere length decreases with aging, and this contributes to cell senescence. Recent evidence supports that telomere length of leukocytes and skeletal muscle cells may be positively associated with healthy living and inversely correlated with the risk of several age-related diseases, including cancer, cardiovascular disease, obesity, diabetes, chronic pain, and stress. In observational studies, higher levels of physical activity or exercise are related to longer telomere lengths in various populations, and athletes tend to have longer telomere lengths than non-athletes. This relationship is particularly evident in older individuals, suggesting a role of physical activity in combating the typical age-induced decrements in telomere length. To date, a small number of exercise interventions have been executed to examine the potential influence of chronic exercise on telomere length, but these studies have not fully established such relationship. Several potential mechanisms through which physical activity or exercise could affect telomere length are discussed, including changes in telomerase activity, oxidative stress, inflammation, and decreased skeletal muscle satellite cell content. Future research is needed to mechanistically examine the effects of various modalities of exercise on telomere length in middle-aged and older adults, as well as in specific clinical populations.

  6. Vitamin D as an adjunctive therapy in asthma. Part 1: A review of potential mechanisms.

    LENUS (Irish Health Repository)

    Kerley, Conor P

    2015-02-27

    Vitamin D deficiency (VDD) is highly prevlalent worldwide. The classical role for vitamin D is to regulate calcium absorption form the gastrointestinal tract and influence bone health. Recently vitamin D receptors and vitamin D metabolic enzymes have been discovered in numerous sites systemically supporting diverse extra-skeletal roles of vitamin D, for example in asthmatic disease. Further, VDD and asthma share several common risk factors including high latitude, winter season, industrialization, poor diet, obesity, and dark skin pigmentation. Vitamin D has been demonstrated to possess potent immunomodulatory effects, including effects on T cells and B cells as well as increasing production of antimicrobial peptides (e.g. cathelicidin). This immunomodulation may lead to asthma specific clinical benefits in terms of decreased bacterial\\/viral infections, altered airway smooth muscle-remodeling and -function as well as modulation of response to standard anti-asthma therapy (e.g. glucocorticoids and immunotherapy). Thus, vitamin D and its deficiency have a number of biological effects that are potentially important in altering the course of disease pathogenesis and severity in asthma. The purpose of this first of a two-part review is to review potential mechanisms whereby altering vitamin D status may influence asthmatic disease.

  7. Honey as a Potential Natural Antioxidant Medicine: An Insight into Its Molecular Mechanisms of Action

    Science.gov (United States)

    Ahmed, Sarfraz; Sulaiman, Siti Amrah; Baig, Atif Amin; Ibrahim, Muhammad; Liaqat, Sana; Fatima, Saira; Jabeen, Sadia; Shamim, Nighat

    2018-01-01

    Honey clasps several medicinal and health effects as a natural food supplement. It has been established as a potential therapeutic antioxidant agent for various biodiverse ailments. Data report that it exhibits strong wound healing, antibacterial, anti-inflammatory, antifungal, antiviral, and antidiabetic effects. It also retains immunomodulatory, estrogenic regulatory, antimutagenic, anticancer, and numerous other vigor effects. Data also show that honey, as a conventional therapy, might be a novel antioxidant to abate many of the diseases directly or indirectly associated with oxidative stress. In this review, these wholesome effects have been thoroughly reviewed to underscore the mode of action of honey exploring various possible mechanisms. Evidence-based research intends that honey acts through a modulatory road of multiple signaling pathways and molecular targets. This road contemplates through various pathways such as induction of caspases in apoptosis; stimulation of TNF-α, IL-1β, IFN-γ, IFNGR1, and p53; inhibition of cell proliferation and cell cycle arrest; inhibition of lipoprotein oxidation, IL-1, IL-10, COX-2, and LOXs; and modulation of other diverse targets. The review highlights the research done as well as the apertures to be investigated. The literature suggests that honey administered alone or as adjuvant therapy might be a potential natural antioxidant medicinal agent warranting further experimental and clinical research. PMID:29492183

  8. Vitiligo blood transcriptomics provides new insights into disease mechanisms and identifies potential novel therapeutic targets.

    Science.gov (United States)

    Dey-Rao, Rama; Sinha, Animesh A

    2017-01-28

    Significant gaps remain regarding the pathomechanisms underlying the autoimmune response in vitiligo (VL), where the loss of self-tolerance leads to the targeted killing of melanocytes. Specifically, there is incomplete information regarding alterations in the systemic environment that are relevant to the disease state. We undertook a genome-wide profiling approach to examine gene expression in the peripheral blood of VL patients and healthy controls in the context of our previously published VL-skin gene expression profile. We used several in silico bioinformatics-based analyses to provide new insights into disease mechanisms and suggest novel targets for future therapy. Unsupervised clustering methods of the VL-blood dataset demonstrate a "disease-state"-specific set of co-expressed genes. Ontology enrichment analysis of 99 differentially expressed genes (DEGs) uncovers a down-regulated immune/inflammatory response, B-Cell antigen receptor (BCR) pathways, apoptosis and catabolic processes in VL-blood. There is evidence for both type I and II interferon (IFN) playing a role in VL pathogenesis. We used interactome analysis to identify several key blood associated transcriptional factors (TFs) from within (STAT1, STAT6 and NF-kB), as well as "hidden" (CREB1, MYC, IRF4, IRF1, and TP53) from the dataset that potentially affect disease pathogenesis. The TFs overlap with our reported lesional-skin transcriptional circuitry, underscoring their potential importance to the disease. We also identify a shared VL-blood and -skin transcriptional "hot spot" that maps to chromosome 6, and includes three VL-blood dysregulated genes (PSMB8, PSMB9 and TAP1) described as potential VL-associated genetic susceptibility loci. Finally, we provide bioinformatics-based support for prioritizing dysregulated genes in VL-blood or skin as potential therapeutic targets. We examined the VL-blood transcriptome in context with our (previously published) VL-skin transcriptional profile to address

  9. Mechanics

    CERN Document Server

    Chester, W

    1979-01-01

    When I began to write this book, I originally had in mind the needs of university students in their first year. May aim was to keep the mathematics simple. No advanced techniques are used and there are no complicated applications. The emphasis is on an understanding of the basic ideas and problems which require expertise but do not contribute to this understanding are not discussed. How­ ever, the presentation is more sophisticated than might be considered appropri­ ate for someone with no previous knowledge of the subject so that, although it is developed from the beginning, some previous acquaintance with the elements of the subject would be an advantage. In addition, some familiarity with element­ ary calculus is assumed but not with the elementary theory of differential equations, although knowledge of the latter would again be an advantage. It is my opinion that mechanics is best introduced through the motion of a particle, with rigid body problems left until the subject is more fully developed. Howev...

  10. Nanoscale copper in the soil–plant system – toxicity and underlying potential mechanisms

    Energy Technology Data Exchange (ETDEWEB)

    Anjum, Naser A., E-mail: anjum@ua.pt [CESAM-Centre for Environmental and Marine Studies & Department of Chemistry, University of Aveiro, 3810-193 Aveiro (Portugal); Adam, Vojtech [Department of Chemistry and Biochemistry, Faculty of Agronomy, Mendel University in Brno, Zemedelska 1, CZ-613 00 Brno (Czech Republic); Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00 Brno (Czech Republic); Kizek, Rene [Central European Institute of Technology, Brno University of Technology, Technicka 3058/10, CZ-616 00 Brno (Czech Republic); Duarte, Armando C.; Pereira, Eduarda [CESAM-Centre for Environmental and Marine Studies & Department of Chemistry, University of Aveiro, 3810-193 Aveiro (Portugal); Iqbal, Muhammad [Department of Botany, Faculty of Science, Hamdard University, New Delhi 110062 (India); Lukatkin, Alexander S. [Department of Botany, Plant Physiology and Ecology, N.P. Ogarev Mordovia State University, Bolshevistskaja Str., 68. Saransk 430005 (Russian Federation); Ahmad, Iqbal, E-mail: ahmadr@ua.pt [CESAM-Centre for Environmental and Marine Studies & Department of Chemistry, University of Aveiro, 3810-193 Aveiro (Portugal); CESAM-Centre for Environmental and Marine Studies & Department of Biology, University of Aveiro, 3810-193 Aveiro (Portugal)

    2015-04-15

    Nanoscale copper particles (nano-Cu) are used in many antimicrobial formulations and products for their antimicrobial activity. They may enter deliberately and/or accidentally into terrestrial environments including soils. Being the major ‘eco-receptors’ of nanoscale particles in the terrestrial ecosystem, soil–microbiota and plants (the soil–plant system) have been used as a model to dissect the potential impact of these particles on the environmental and human health. In the soil–plant system, the plant can be an indirect non-target organism of the soil-associated nano-Cu that may in turn affect plant-based products and their consumers. By all accounts, information pertaining to nano-Cu toxicity and the underlying potential mechanisms in the soil–plant system remains scanty, deficient and little discussed. Therefore, based on some recent reports from (bio)chemical, molecular and genetic studies of nano-Cu versus soil–plant system, this article: (i) overviews the status, chemistry and toxicity of nano-Cu in soil and plants, (ii) discusses critically the poorly understood potential mechanisms of nano-Cu toxicity and tolerance both in soil–microbiota and plants, and (iii) proposes future research directions. It appears from studies hitherto made that the uncontrolled generation and inefficient metabolism of reactive oxygen species through different reactions are the major factors underpinning the overall nano-Cu consequences in both the systems. However, it is not clear whether the nano-Cu or the ion released from it is the cause of the toxicity. We advocate to intensify the multi-approach studies focused at a complete characterization of the nano-Cu, its toxicity (during life cycles of the least-explored soil–microbiota and plants), and behavior in an environmentally relevant terrestrial exposure setting. Such studies may help to obtain a deeper insight into nano-Cu actions and address adequately the nano-Cu-associated safety concerns in the

  11. Whitings as a Potential Mechanism for Controlling Atmospheric Carbon Dioxide Concentrations – Final Project Report

    Energy Technology Data Exchange (ETDEWEB)

    Brady D. Lee; William A. Apel; Michelle R. Walton

    2006-03-01

    Species of cyanobacteria in the genera Synechococcus and Synechocystis are known to be the catalysts of a phenomenon called "whitings", which is the formation and precipitation of fine-grained CaCO3 particles. Whitings occur when the cyanobacteria fix atmospheric CO2 through the formation of CaCO3 on their cell surfaces which leads to precipitation to the ocean floor and subsequent entombment in mud. Whitings represent one potential mechanism for CO2 sequestration. Research was performed to determine the ability of various strains of Synechocystis and Synechococcus to calcify when grown in microcosms amended with 2.5 mM HCO3- and 3.4 mM Ca2+. Results indicated that while all strains tested have the ability to calcify, only two, Synechococcus species, strains PCC 8806 and PCC 8807, were able to calcify to the extent that CaCO3 was precipitated. Enumeration of the cyanobacterial cultures during testing indicated that cell density did not appear to have an effect on calcification. Factors that had the greatest effect on calcification were CO2 removal and subsequent generation of alkaline pH. As CO2 was removed, growth medium pH increased and soluble Ca2+ was removed from solution. The largest increases in growth medium pH occurred when CO2 levels dropped below 400 ppmv. Precipitation of CaCO3 catalyzed by the growth and physiology of cyanobacteria in the Genus Synechococcus represents a potential mechanism for sequestration of atmospheric CO2 produced during the burning of coal for power generation. Synechococcus sp. strain PCC 8806 and Synechococcus sp. strain PCC 8807 were tested in microcosm experiments for their ability to calcify when exposed to a fixed calcium concentration of 3.4 mM and dissolved inorganic carbon concentrations of 0.5, 1.25 and 2.5 mM. Synechococcus sp. strain PCC 8806 removed calcium continuously over the duration of the experiment producing approximately 18.6 mg of solid-phase calcium. Calcium removal occurred over a two-day time period when

  12. Nanoscale copper in the soil–plant system – toxicity and underlying potential mechanisms

    International Nuclear Information System (INIS)

    Anjum, Naser A.; Adam, Vojtech; Kizek, Rene; Duarte, Armando C.; Pereira, Eduarda; Iqbal, Muhammad; Lukatkin, Alexander S.; Ahmad, Iqbal

    2015-01-01

    Nanoscale copper particles (nano-Cu) are used in many antimicrobial formulations and products for their antimicrobial activity. They may enter deliberately and/or accidentally into terrestrial environments including soils. Being the major ‘eco-receptors’ of nanoscale particles in the terrestrial ecosystem, soil–microbiota and plants (the soil–plant system) have been used as a model to dissect the potential impact of these particles on the environmental and human health. In the soil–plant system, the plant can be an indirect non-target organism of the soil-associated nano-Cu that may in turn affect plant-based products and their consumers. By all accounts, information pertaining to nano-Cu toxicity and the underlying potential mechanisms in the soil–plant system remains scanty, deficient and little discussed. Therefore, based on some recent reports from (bio)chemical, molecular and genetic studies of nano-Cu versus soil–plant system, this article: (i) overviews the status, chemistry and toxicity of nano-Cu in soil and plants, (ii) discusses critically the poorly understood potential mechanisms of nano-Cu toxicity and tolerance both in soil–microbiota and plants, and (iii) proposes future research directions. It appears from studies hitherto made that the uncontrolled generation and inefficient metabolism of reactive oxygen species through different reactions are the major factors underpinning the overall nano-Cu consequences in both the systems. However, it is not clear whether the nano-Cu or the ion released from it is the cause of the toxicity. We advocate to intensify the multi-approach studies focused at a complete characterization of the nano-Cu, its toxicity (during life cycles of the least-explored soil–microbiota and plants), and behavior in an environmentally relevant terrestrial exposure setting. Such studies may help to obtain a deeper insight into nano-Cu actions and address adequately the nano-Cu-associated safety concerns in the

  13. Criteria, potentials and costs of forestry activities to sequester carbon within the framework of the clean development mechanism

    NARCIS (Netherlands)

    Waterloo, M.J.; Spiertz, P.H.; Diemont, W.H.; Emmer, I.; Aalders, E.; Wichink Kruit, R.J.; Kabat, P.

    2003-01-01

    Forest activities in developing countries can be used to sequester carbon for gaining emission reductions within the Clean Development Mechanism of the Kyoto Protocol. This study has assessed the potentials and costs for carbon sequestration through afforestation, reforestation and deforestation

  14. Phosphorus in Hermatypic Coral Skeleton: Incorporation Mechanisms and a Potential Seawater Phosphate Proxy

    Science.gov (United States)

    Lavigne, M. G.; Sherrell, R. M.; Linsley, B. K.; Desenfant, F.

    2006-12-01

    Records of surface water nutrient availability with sub-seasonal resolution would provide crucial evidence in understanding the effects of annual to centennial scale climate variability on oceanic primary production. A direct coral proxy for seawater phosphate would complement low resolution records from established but quantitatively uncertain indirect proxies such as planktonic foraminiferal Cd/Ca. Very recently, Montagna et al. (2006) suggested that LA-ICP-MS measurements of P/Ca in deep sea corals could be used to reconstruct deep water phosphate, although the unknown phosphorus incorporation mechanism adds uncertainty to this emerging proxy.1 Our group is investigating the chemical form and incorporation mechanism for phosphorus in the hermatypic corals Montastrea faveolata (Martinique, Caribbean) and Porites lutea (Rarotonga, South Pacific) using laser ablation and solution phase ICP-MS techniques. We have well calibrated analyses of cleaned and uncleaned micro-drilled samples for a number of trace elements including P by solution phase HR-ICP-MS in Caribbean Montastrea coral. We have also analyzed the Rarotonga Porites coral by LA-ICP-MS resulting in high resolution (~ bi-weekly) phosphorus data over ~ 2.5 years. Phosphorus was resistant to rigorous solution cleaning of the drilled Martinique coral samples. This suggests incorporation largely in inorganic lattice-bound sites rather than as residual organic P or in association with Fe- Mn oxides. High skeletal P/Ca values are found just under the growing surface in the Martinique coral, decreasing exponentially within several millimeters, suggesting that organic P is remineralized quickly, leaving the residual ~constant signal. Both of these corals from the upper 20m had lower P/Ca than deep sea corals (100 - 1200 μmol/mol)1, and the mean P/Ca in Rarotonga Porites (~46 μmol/mol) is higher than in the Martinique Montastrea (18 μmol/mol). Both observations are consistent with the increase in PO4 with depth

  15. Current Understanding of Physicochemical Mechanisms for Cell Membrane Penetration of Arginine-rich Cell Penetrating Peptides: Role of Glycosaminoglycan Interactions.

    Science.gov (United States)

    Takechi-Haraya, Yuki; Saito, Hiroyuki

    2018-01-01

    Arginine-rich cell penetrating peptides (CPPs) are very promising drug carriers to deliver membrane-impermeable pharmaceuticals, such as siRNA, bioactive peptides and proteins. CPPs directly penetrate into cells across cell membranes via a spontaneous energy-independent process, in which CPPs appear to interact with acidic lipids in the outer leaflet of the cell membrane. However, acidic lipids represent only 10 to 20% of the total membrane lipid content and in mammalian cell membranes they are predominantly located in the inner leaflet. Alternatively, CPPs favorably bind in a charge density- dependent manner to negatively charged, sulfated glycosaminoglycans (GAGs), such as heparan sulfate and chondroitin sulfate, which are abundant on the cell surface and are involved in many biological functions. We have recently demonstrated that the interaction of CPPs with sulfated GAGs plays a critical role in their direct cell membrane penetration: the favorable enthalpy contribution drives the high-affinity binding of arginine-rich CPPs to sulfated GAGs, initiating an efficient cell membrane penetration. The favorable enthalpy gain is presumably mainly derived from a unique property of the guanidino group of arginine residues forming multidentate hydrogen bonding with sulfate and carboxylate groups in GAGs. Such interactions can be accompanied with charge neutralization of arginine-rich CPPs, promoting their partition into cell membranes. This review summarizes the current understanding of the physicochemical mechanism for lipid membrane penetration of CPPs, and discusses the role of the GAG interactions on the cell membrane penetration of CPPs. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  16. Application of isotope exchange based mass spectrometry to understand the mechanism of inhibition of sickle hemoglobin polymerization upon oxygenation.

    Science.gov (United States)

    Das, Rajdeep; Mitra, Amrita; Bhat, Vijay; Mandal, Amit Kumar

    2017-07-01

    Sickle hemoglobin (HbS) polymerization initiates in the deoxy state with the binding of hydrophobic patch formed by the isopropyl group of βVal6 residue of a hemoglobin tetramer with the hydrophobic pocket of another tetramer, whose hydrophobic patch binds to the hydrophobic groove of a third molecule. Subsequent elongation of a single stranded polymer followed by the formation of a double strand and finally combination of seven such pairs of double strands results in a fourteen stranded fibrous polymer. Precipitation of this fiber inside the erythrocytes results in sickling of red blood cells. Surprisingly, the polymerization does not occur in the oxy state of HbS. Due to the unavailability of crystal structure of oxy form of HbS, the molecular basis of inhibition of polymerization in the oxy state is unknown to date. In the present study, we have attempted to understand the molecular mechanism of inhibition of polymerization by exploiting the exchange of backbone amide hydrogens of HbS with deuterated solvent. Hydrogen/deuterium exchange kinetics of peptide amide hydrogens of both oxy and deoxy form of HbS were monitored through ESI mass spectrometry. Upon oxygenation changes in the conformational flexibility across different regions of α and β globin chains in the tetrameric HbS molecule were investigated. It was observed that oxygenation led to perturbation in the conformation of several residues around the hydrophobic patch, groove of a tetramer and axial, lateral contacts across the double strands that are involved in HbS polymerization. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Understanding the undelaying mechanism of HA-subtyping in the level of physic-chemical characteristics of protein.

    Science.gov (United States)

    Ebrahimi, Mansour; Aghagolzadeh, Parisa; Shamabadi, Narges; Tahmasebi, Ahmad; Alsharifi, Mohammed; Adelson, David L; Hemmatzadeh, Farhid; Ebrahimie, Esmaeil

    2014-01-01

    The evolution of the influenza A virus to increase its host range is a major concern worldwide. Molecular mechanisms of increasing host range are largely unknown. Influenza surface proteins play determining roles in reorganization of host-sialic acid receptors and host range. In an attempt to uncover the physic-chemical attributes which govern HA subtyping, we performed a large scale functional analysis of over 7000 sequences of 16 different HA subtypes. Large number (896) of physic-chemical protein characteristics were calculated for each HA sequence. Then, 10 different attribute weighting algorithms were used to find the key characteristics distinguishing HA subtypes. Furthermore, to discover machine leaning models which can predict HA subtypes, various Decision Tree, Support Vector Machine, Naïve Bayes, and Neural Network models were trained on calculated protein characteristics dataset as well as 10 trimmed datasets generated by attribute weighting algorithms. The prediction accuracies of the machine learning methods were evaluated by 10-fold cross validation. The results highlighted the frequency of Gln (selected by 80% of attribute weighting algorithms), percentage/frequency of Tyr, percentage of Cys, and frequencies of Try and Glu (selected by 70% of attribute weighting algorithms) as the key features that are associated with HA subtyping. Random Forest tree induction algorithm and RBF kernel function of SVM (scaled by grid search) showed high accuracy of 98% in clustering and predicting HA subtypes based on protein attributes. Decision tree models were successful in monitoring the short mutation/reassortment paths by which influenza virus can gain the key protein structure of another HA subtype and increase its host range in a short period of time with less energy consumption. Extracting and mining a large number of amino acid attributes of HA subtypes of influenza A virus through supervised algorithms represent a new avenue for understanding and

  18. Use of rheometry and {sup 1}H NMR spectroscopy for understanding the mechanisms behind the generation of coking pressure

    Energy Technology Data Exchange (ETDEWEB)

    Karen M. Steel; Miguel Castro Diaz; John W. Patrick; Colin E. Snape [Nottingham University, Nottingham (United Kingdom). Nottingham Fuel and Energy Centre, School of Chemical, Environmental and Mining Engineering

    2004-10-01

    The fluid phase which forms during carbonization of a range of coals was studied using rheometry and {sup 1}H NMR spectroscopy to study the mechanisms behind the generation of excessive wall pressures during coking. It is proposed that high coking pressures are generated for low volatile matter coals when the temperature of maximum fluidity (T{sub mf}) is {gt} 465{degree}C, the minimum complex viscosity ({eta}{asterisk}) is {gt} 10{sup 5} Pa s, the percentage of mobile 1H (fluid phase) is {lt} 40%, and the {sup 1}H mobility in the fluid phase is {lt} 65 {mu}s. It is suggested for these coals that the particles fuse to form a rigid network containing pockets of fluid material which have a low fluidity and do not link up. This arrangement could present an impermeable barrier for gas flow and force the gas to the coal side where it builds up in a diminishing region to a critical level, causing pressure on the walls. The magnitude of the pressure generated may be proportional to T{sub mf} and {eta}{asterisk} and inversely proportional to the percentage and mobility of mobile {sup 1}H. It was also found that a high volatile coal which formed a highly fluid phase over a broad temperature range gave rise to a significant coking pressure. In this case, it is proposed that the sheer expansion of the coal charge as it converts to gas and liquid phases is the reason for pressure on the oven walls. These proposals agree with current thinking on the generation of coking pressure. This work is based on the testing of only nine samples and further work is planned to gain a greater fundamental understanding of fluidity development from which models for predicting coking pressure and coke quality for coal blends may be developed. 20 refs., 10 figs., 5 tabs.

  19. Understanding the undelaying mechanism of HA-subtyping in the level of physic-chemical characteristics of protein.

    Directory of Open Access Journals (Sweden)

    Mansour Ebrahimi

    Full Text Available The evolution of the influenza A virus to increase its host range is a major concern worldwide. Molecular mechanisms of increasing host range are largely unknown. Influenza surface proteins play determining roles in reorganization of host-sialic acid receptors and host range. In an attempt to uncover the physic-chemical attributes which govern HA subtyping, we performed a large scale functional analysis of over 7000 sequences of 16 different HA subtypes. Large number (896 of physic-chemical protein characteristics were calculated for each HA sequence. Then, 10 different attribute weighting algorithms were used to find the key characteristics distinguishing HA subtypes. Furthermore, to discover machine leaning models which can predict HA subtypes, various Decision Tree, Support Vector Machine, Naïve Bayes, and Neural Network models were trained on calculated protein characteristics dataset as well as 10 trimmed datasets generated by attribute weighting algorithms. The prediction accuracies of the machine learning methods were evaluated by 10-fold cross validation. The results highlighted the frequency of Gln (selected by 80% of attribute weighting algorithms, percentage/frequency of Tyr, percentage of Cys, and frequencies of Try and Glu (selected by 70% of attribute weighting algorithms as the key features that are associated with HA subtyping. Random Forest tree induction algorithm and RBF kernel function of SVM (scaled by grid search showed high accuracy of 98% in clustering and predicting HA subtypes based on protein attributes. Decision tree models were successful in monitoring the short mutation/reassortment paths by which influenza virus can gain the key protein structure of another HA subtype and increase its host range in a short period of time with less energy consumption. Extracting and mining a large number of amino acid attributes of HA subtypes of influenza A virus through supervised algorithms represent a new avenue for

  20. Metatranscriptome Analysis of Fig Flowers Provides Insights into Potential Mechanisms for Mutualism Stability and Gall Induction.

    Directory of Open Access Journals (Sweden)

    Ellen O Martinson

    Full Text Available A striking property of the mutualism between figs and their pollinating wasps is that wasps consistently oviposit in the inner flowers of the fig syconium, which develop into galls that house developing larvae. Wasps typically do not use the outer ring of flowers, which develop into seeds. To better understand differences between gall and seed flowers, we used a metatranscriptomic approach to analyze eukaryotic gene expression within fig flowers at the time of oviposition choice and early gall development. Consistent with the unbeatable seed hypothesis, we found significant differences in gene expression between gall- and seed flowers in receptive syconia prior to oviposition. In particular, transcripts assigned to flavonoids and carbohydrate metabolism were significantly up-regulated in gall flowers relative to seed flowers. In response to oviposition, gall flowers significantly up-regulated the expression of chalcone synthase, which previously has been connected to gall formation in other plants. We propose several genes encoding proteins with signal peptides or associations with venom of other Hymenoptera as candidate genes for gall initiation or growth. This study simultaneously evaluates the gene expression profile of both mutualistic partners in a plant-insect mutualism and provides insight into a possible stability mechanism in the ancient fig-fig wasp association.

  1. Coumarins as Potential Antioxidant Agents Complemented with Suggested Mechanisms and Approved by Molecular Modeling Studies

    Directory of Open Access Journals (Sweden)

    Yasameen K. Al-Majedy

    2016-01-01

    Full Text Available Syntheses of coumarins, which are a structurally interesting antioxidant activity, was done in this article. The modification of 7-hydroxycoumarin by different reaction steps was done to yield target compounds. Molecular structures were characterized by different spectroscopical techniques (Fourier transformation infrared and nuclear magnetic resonance. Antioxidant activities were performed by using various in vitro spectrophometric assays against 1,1-diphenyl-2-picrylhydrazyl (DPPH radical and hydrogen peroxide (H2O2. All compounds exhibited high efficiency as antioxidants compared to ascorbic acid. The highest efficiency scavenging activity was found for compound 3 (91.0 ± 5.0, followed by compounds 2 and 4 (88.0 ± 2.00; and 87.0 ± 3.00. Ascorbic acid C was used as a standard drug with a percentage inhibition of 91.00 ± 1.5. The mechanism of the synthesized compounds as antioxidants was also studied. Hartree–Fock–based quantum chemical studies have been carried out with the basis set to 3-21G, in order to obtain information about the three-dimensional (3D geometries, electronic structure, molecular modeling, and electronic levels, namely HOMO (highest occupied molecular orbital and LUMO (lowest unoccupied molecular orbital, to understand the antioxidant activity for the synthesized compounds.

  2. Metatranscriptome Analysis of Fig Flowers Provides Insights into Potential Mechanisms for Mutualism Stability and Gall Induction.

    Science.gov (United States)

    Martinson, Ellen O; Hackett, Jeremiah D; Machado, Carlos A; Arnold, A Elizabeth

    2015-01-01

    A striking property of the mutualism between figs and their pollinating wasps is that wasps consistently oviposit in the inner flowers of the fig syconium, which develop into galls that house developing larvae. Wasps typically do not use the outer ring of flowers, which develop into seeds. To better understand differences between gall and seed flowers, we used a metatranscriptomic approach to analyze eukaryotic gene expression within fig flowers at the time of oviposition choice and early gall development. Consistent with the unbeatable seed hypothesis, we found significant differences in gene expression between gall- and seed flowers in receptive syconia prior to oviposition. In particular, transcripts assigned to flavonoids and carbohydrate metabolism were significantly up-regulated in gall flowers relative to seed flowers. In response to oviposition, gall flowers significantly up-regulated the expression of chalcone synthase, which previously has been connected to gall formation in other plants. We propose several genes encoding proteins with signal peptides or associations with venom of other Hymenoptera as candidate genes for gall initiation or growth. This study simultaneously evaluates the gene expression profile of both mutualistic partners in a plant-insect mutualism and provides insight into a possible stability mechanism in the ancient fig-fig wasp association.

  3. Mechanical, dynamic-mechanical and thermal properties of soy protein-based thermoplastics with potential biomedical applications

    NARCIS (Netherlands)

    Vaz, C.A.; Mano, J.F.; Fossen, M.; Tuil, van R.F.; Graaf, de L.A.; Reis, R.L.; Cunha, A.A.

    2002-01-01

    In this study the tensile and the dynamic-mechanical behavior of injection-molded samples of various soy protein thermoplastic compounds were evaluated as a function of the amount of glycerol, type and amount of ceramic reinforcement, and eventual incorporation of coupling agents. The incorporation

  4. Quantum Mechanics/Molecular Mechanics Method Combined with Hybrid All-Atom and Coarse-Grained Model: Theory and Application on Redox Potential Calculations.

    Science.gov (United States)

    Shen, Lin; Yang, Weitao

    2016-04-12

    We developed a new multiresolution method that spans three levels of resolution with quantum mechanical, atomistic molecular mechanical, and coarse-grained models. The resolution-adapted all-atom and coarse-grained water model, in which an all-atom structural description of the entire system is maintained during the simulations, is combined with the ab initio quantum mechanics and molecular mechanics method. We apply this model to calculate the redox potentials of the aqueous ruthenium and iron complexes by using the fractional number of electrons approach and thermodynamic integration simulations. The redox potentials are recovered in excellent accordance with the experimental data. The speed-up of the hybrid all-atom and coarse-grained water model renders it computationally more attractive. The accuracy depends on the hybrid all-atom and coarse-grained water model used in the combined quantum mechanical and molecular mechanical method. We have used another multiresolution model, in which an atomic-level layer of water molecules around redox center is solvated in supramolecular coarse-grained waters for the redox potential calculations. Compared with the experimental data, this alternative multilayer model leads to less accurate results when used with the coarse-grained polarizable MARTINI water or big multipole water model for the coarse-grained layer.

  5. Potential mechanisms supporting the value of motor cortex stimulation to treat chronic pain syndromes

    Directory of Open Access Journals (Sweden)

    Marcos Fabio DosSantos

    2016-02-01

    Full Text Available Throughout the first years of the twenty-first century, neurotechnologies such as motor cortex stimulation (MCS, transcranial magnetic stimulation (TMS and transcranial direct current stimulation (tDCS have attracted scientific attention and been considered as potential tools to centrally modulate chronic pain, especially for those conditions more difficult to manage and refractory to all types of available pharmacological therapies. Interestingly, although the role of the motor cortex in pain has not been fully clarified, it is one of the cortical areas most commonly targeted by invasive and non-invasive neuromodulation technologies. Recent studies have provided significant advances concerning the establishment of the clinical effectiveness of primary motor cortex stimulation to treat different chronic pain syndromes. Concurrently, the neuromechanisms related to each method of primary motor cortex (M1 modulation have been unveiled. In this respect, the most consistent scientific evidence originates from MCS studies, which indicate the activation of top-down controls driven by M1 stimulation. This concept has also been applied to explain M1-TMS mechanisms. Nevertheless, activation of remote areas in the brain, including cortical and subcortical structures, has been reported with both invasive and non-invasive methods and the participation of major neurotransmitters (e.g. glutamate, GABA and serotonin as well as the release of endogenous opioids has been demonstrated. In this critical review, the putative mechanisms underlying the use of motor cortex stimulation to provide relief from chronic migraine and other types of chronic pain are discussed. Emphasis is placed on the most recent scientific evidence obtained from chronic pain research studies involving MCS and non-invasive neuromodulation methods (e.g. tDCS and TMS, which are analyzed comparatively.

  6. Potential Mechanisms Supporting the Value of Motor Cortex Stimulation to Treat Chronic Pain Syndromes.

    Science.gov (United States)

    DosSantos, Marcos F; Ferreira, Natália; Toback, Rebecca L; Carvalho, Antônio C; DaSilva, Alexandre F

    2016-01-01

    Throughout the first years of the twenty-first century, neurotechnologies such as motor cortex stimulation (MCS), transcranial magnetic stimulation (TMS), and transcranial direct current stimulation (tDCS) have attracted scientific attention and been considered as potential tools to centrally modulate chronic pain, especially for those conditions more difficult to manage and refractory to all types of available pharmacological therapies. Interestingly, although the role of the motor cortex in pain has not been fully clarified, it is one of the cortical areas most commonly targeted by invasive and non-invasive neuromodulation technologies. Recent studies have provided significant advances concerning the establishment of the clinical effectiveness of primary MCS to treat different chronic pain syndromes. Concurrently, the neuromechanisms related to each method of primary motor cortex (M1) modulation have been unveiled. In this respect, the most consistent scientific evidence originates from MCS studies, which indicate the activation of top-down controls driven by M1 stimulation. This concept has also been applied to explain M1-TMS mechanisms. Nevertheless, activation of remote areas in the brain, including cortical and subcortical structures, has been reported with both invasive and non-invasive methods and the participation of major neurotransmitters (e.g., glutamate, GABA, and serotonin) as well as the release of endogenous opioids has been demonstrated. In this critical review, the putative mechanisms underlying the use of MCS to provide relief from chronic migraine and other types of chronic pain are discussed. Emphasis is placed on the most recent scientific evidence obtained from chronic pain research studies involving MCS and non-invasive neuromodulation methods (e.g., tDCS and TMS), which are analyzed comparatively.

  7. Electrophysiological potentials reveal cortical mechanisms for mental imagery, mental simulation, and grounded (embodied cognition

    Directory of Open Access Journals (Sweden)

    Haline E. Schendan

    2012-09-01

    Full Text Available Grounded cognition theory proposes that cognition, including meaning, is grounded in sensorimotor processing. The mechanism for grounding cognition is mental simulation, which is a type of mental imagery that re-enacts modal processing. To reveal top-down, cortical mechanisms for mental simulation of shape, event-related potentials were recorded to face and object pictures preceded by mental imagery of a picture. Mental imagery of the identical face or object (congruous condition facilitated not only categorical perception (VPP/N170 but also later visual knowledge (N3[00] complex and linguistic knowledge (N400 for faces more than objects, and strategic semantic analysis (late positive complex between 200 and 700 ms. The later effects resembled semantic congruity effects with pictures. Mental imagery also facilitated category decisions, as a P3(00 peaked earlier for congruous than incongruous (other category pictures, resembling the case when identical pictures repeat immediately. Thus mental imagery mimics semantic congruity and immediate repetition priming processes with pictures. Perception control results showed the opposite for faces and were in the same direction for objects: Perceptual repetition adapts (and so impairs processing of perceived faces from categorical perception onwards, but primes processing of objects during categorical perception, visual knowledge processes, and strategic semantic analysis. For both imagery and perception, differences between faces and objects support domain-specificity and indicate that cognition is grounded in modal processing. Altogether, this direct neural evidence reveals that top-down processes of mental imagery sustain an imagistic representation that mimics perception well