WorldWideScience

Sample records for junction function size

  1. Transparency of atom-sized superconducting junctions

    International Nuclear Information System (INIS)

    Van-der-Post, N.; Peters, E.T.; Van Ruitenbeek, J.M.; Yanson, I.K.

    1995-01-01

    We discuss the transparency of atom-size superconducting tunnel junctions by comparing experimental values of the normal resistance and Subgap Structure with the theoretical predictions for these phenomena by Landauer's formula and Multiple Andreev Reflection, respectively

  2. Diabetes Increases Cryoinjury Size with Associated Effects on Cx43 Gap Junction Function and Phosphorylation in the Mouse Heart.

    Science.gov (United States)

    Palatinus, Joseph A; Gourdie, Robert G

    2016-01-01

    Diabetic patients develop larger myocardial infarctions and have an increased risk of death following a heart attack. The poor response to myocardial injury in the diabetic heart is likely related to the many metabolic derangements from diabetes that create a poor substrate in general for wound healing, response to injury and infection. Studies in rodents have implicated a role for the gap junction protein connexin 43 (Cx43) in regulating the injury response in diabetic skin wounds. In this study, we sought to determine whether diabetes alters Cx43 molecular interactions or intracellular communication in the cryoinjured STZ type I diabetic mouse heart. We found that epicardial cryoinjury size is increased in diabetic mice and this increase is prevented by preinjury insulin administration. Consistent with these findings, we found that intercellular coupling via gap junctions is decreased after insulin administration in diabetic and nondiabetic mice. This decrease in coupling is associated with a concomitant increase in phosphorylation of Cx43 at serine 368, a residue known to decrease channel conductance. Taken together, our results suggest that insulin regulates both gap junction-mediated intercellular communication and injury propagation in the mouse heart.

  3. Functional anatomy of the human ureterovesical junction

    NARCIS (Netherlands)

    Roshani, H.; Dabhoiwala, N. F.; Verbeek, F. J.; Lamers, W. H.

    1996-01-01

    BACKGROUND: The valve function of the ureterovesical-junction (UVJ) is responsible for protection of the low pressure upper urinary tract from the refluxing of urine from the bladder. Controversy about the microanatomy of the human ureterovesical-junction persists. METHODS: Ten (3 male and 7 female)

  4. impairs gap junction function causing congenital cataract

    Indian Academy of Sciences (India)

    Navya

    2017-03-24

    Mar 24, 2017 ... experiment showed a lower dye diffusion distance of Cx46 V44M cells, ... Studies of connexins show that channel gating and permeability .... have found that connexin assembled into gap junction plaques is not soluble in 1% ..... high glucose reduces gap junction activity in microvascular endothelial cells.

  5. impairs gap junction function causing congenital cataract

    Indian Academy of Sciences (India)

    LIJUAN CHEN

    2017-12-20

    Dec 20, 2017 ... showed a lower dye diffusion distance of Cx46 V44M cells, which indicates that the gap junction intercellular ... permeability could be affected by alterations of charged residues of .... bled into gap junction plaques is not soluble in 1% Triton ..... regulation of connexin 43 expression by high glucose reduces.

  6. Quantum decrease of capacitance in a nanometer-sized tunnel junction

    Science.gov (United States)

    Untiedt, C.; Saenz, G.; Olivera, B.; Corso, M.; Sabater, C.; Pascual, J. I.

    2013-03-01

    We have studied the capacitance of the tunnel junction defined by the tip and sample of a Scanning Tunnelling Microscope through the measurement of the electrostatic forces and impedance of the junction. A decrease of the capacitance when a tunnel current is present has shown to be a more general phenomenon as previously reported in other systems. On another hand, an unexpected reduction of the capacitance is also observed when increasing the applied voltage above the work function energy of the electrodes to the Field Emission (FE) regime, and the decrease of capacitance due to a single FE-Resonance has been characterized. All these effects should be considered when doing measurements of the electronic characteristics of nanometer-sized electronic devices and have been neglected up to date. Spanish government (FIS2010-21883-C02-01, CONSOLIDER CSD2007-0010), Comunidad Valenciana (ACOMP/2012/127 and PROMETEO/2012/011)

  7. Functional Molecular Junctions Derived from Double Self-Assembled Monolayers.

    Science.gov (United States)

    Seo, Sohyeon; Hwang, Eunhee; Cho, Yunhee; Lee, Junghyun; Lee, Hyoyoung

    2017-09-25

    Information processing using molecular junctions is becoming more important as devices are miniaturized to the nanoscale. Herein, we report functional molecular junctions derived from double self-assembled monolayers (SAMs) intercalated between soft graphene electrodes. Newly assembled molecular junctions are fabricated by placing a molecular SAM/(top) electrode on another molecular SAM/(bottom) electrode by using a contact-assembly technique. Double SAMs can provide tunneling conjugation across the van der Waals gap between the terminals of each monolayer and exhibit new electrical functions. Robust contact-assembled molecular junctions can act as platforms for the development of equivalent contact molecular junctions between top and bottom electrodes, which can be applied independently to different kinds of molecules to enhance either the structural complexity or the assembly properties of molecules. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. The functional anatomy of the ureterovesical junction

    NARCIS (Netherlands)

    Thomson, A. S.; Dabhoiwala, N. F.; Verbeek, F. J.; Lamers, W. H.

    1994-01-01

    To obtain a new insight into the anti-reflux mechanism of the ureterovesical junction by studying the topographical anatomy of the juxta- and intravesical ureter and its relationship to the surrounding bladder musculature. Fresh pig bladders were fixed, frozen and serially sectioned. Enzyme

  9. Lift-off process for deep-submicron-size junctions using supercritical CO2

    International Nuclear Information System (INIS)

    Fukushima, A.; Kubota, H.; Yuasa, S.; Takahachi, T.; Kadoriku, S.; Miyake, K.

    2007-01-01

    Deep-submicron-size (∼100-nm-size) junctions are a key element to investigate spin-torque transfer phenomena such as current induced magnetization reversal or the spin-torque diode effect. In the fabrication of submicron-size junctions using an etching method, the lift-off process after the etching process tends to be difficult as the size of junctions shrinks. In this study, we present a new lift-off process using supercritical CO 2 . In this process, the samples were immersed in solvent (mixture of N-Methyl-2-pyrrolidone and isopropanol), and pressurized by CO 2 gas. The CO 2 gas then went into supercritical phase and the solvent was removed by a continuous flow of CO 2 . We obtained considerable yield rate (success ratio in lift-off process) of more than 50% for the samples down to 100-nm-size junctions

  10. Treatment with the gap junction modifier rotigaptide (ZP123) reduces infarct size in rats with chronic myocardial infarction

    DEFF Research Database (Denmark)

    Haugan, Ketil; Marcussen, Niels; Kjølbye, Anne Louise

    2006-01-01

    Treatment with non-selective drugs (eg, long-chain alcohols, halothane) that reduce gap junction intercellular communication (GJIC) is associated with reduced infarct size after myocardial infarction (MI). Therefore, it has been suggested that gap junction intercellular communication stimulating ...

  11. Influence of functional groups on charge transport in molecular junctions

    DEFF Research Database (Denmark)

    Mowbray, Duncan; Jones, Glenn; Thygesen, Kristian Sommer

    2008-01-01

    Using density functional theory (DFT), we analyze the influence of five classes of functional groups, as exemplified by NO2, OCH3, CH3, CCl3, and I, on the transport properties of a 1,4-benzenedithiolate (BDT) and 1,4-benzenediamine (BDA) molecular junction with gold electrodes. Our analysis...... demonstrates how ideas from functional group chemistry may be used to engineer a molecule's transport properties, as was shown experimentally and using a semiempirical model for BDA [Nano Lett. 7, 502 (2007)]. In particular, we show that the qualitative change in conductance due to a given functional group can...... be predicted from its known electronic effect (whether it is sigma/pi donating/withdrawing). However, the influence of functional groups on a molecule's conductance is very weak, as was also found in the BDA experiments. The calculated DFT conductances for the BDA species are five times larger than...

  12. Determination of size distribution function

    International Nuclear Information System (INIS)

    Teshome, A.; Spartakove, A.

    1987-05-01

    The theory of a method is outlined which gives the size distribution function (SDF) of a polydispersed system of non-interacting colloidal and microscopic spherical particles, having sizes in the range 0-10 -5 cm., from a gedanken experimental scheme. It is assumed that the SDF is differentiable and the result is obtained for rotational frequency in the order of 10 3 (sec) -1 . The method may be used independently, but is particularly useful in conjunction with an alternate method described in a preceding paper. (author). 8 refs, 2 figs

  13. Numerical simulation of droplet formation regimes and sizes in microfluidic T-junction devices

    Science.gov (United States)

    Nekouei, Mehdi; Vanapalli, Siva

    2014-11-01

    The T-junction geometry has been widely used for producing monodisperse droplets in microfluidic devices. Droplet formation regimes and sizes are expected to depend on a variety of conditions including flow rates, capillary number, channel geometry and viscosity ratio. Experiments have investigated drop production at a T-junction in a narrow control parameter space and developed analytical models for specific operating regimes. In this study, we take advantage of numerical simulations based on volume-of-fluid method to explore this broad parameter space systematically, and contrast our results with prior experimental data. We find our simulations predict well the regimes of squeezing, dripping and jetting. We also observe that our drop size data is in good agreement with three different experimental reports. Although our results match experimental data, the analytical models do not agree with each other since they are based on specific operating conditions. We use numerical simulations to elucidate the missing components in the physics of drop formation at a T-junction, with an attempt to reconcile existing analytical models.

  14. Fast electric control of the droplet size in a microfluidic T-junction droplet generator

    Science.gov (United States)

    Shojaeian, Mostafa; Hardt, Steffen

    2018-05-01

    The effect of DC electric fields on the generation of droplets of water and xanthan gum solutions in sunflower oil at a microfluidic T-junction is experimentally studied. The electric field leads to a significant reduction of the droplet diameter, by about a factor of 2 in the case of water droplets. The droplet size can be tuned by varying the electric field strength, an effect that can be employed to produce a stream of droplets with a tailor-made size sequence. Compared to the case of purely hydrodynamic droplet production without electric fields, the electric control has about the same effect on the droplet size if the electric stress at the liquid/liquid interface is the same as the hydrodynamic stress.

  15. Size dependence of magnetization reversal of ring shaped magnetic tunnel junction

    International Nuclear Information System (INIS)

    Chen, C.C.; Kuo, C.Y.; Chang, Y.C.; Chang, C.C.; Horng, Lance; Wu, Teho; Chern, G.; Huang, C.Y.; Tsunoda, M.; Takahashi, M.; Wu, J.C.

    2007-01-01

    The size dependence of magnetization reversal of magnetic tunnel junction (MTJ) rings has been investigated. The MTJ rings, with outer diameter of 4, 2 and 1 μm and inner diameter of 1.5, 1 and 0.5 μm were fabricated by a top-down technique. The magnetoresistance curves manifest all of the magnetic domain configurations during magnetization reversal in different sized rings. Various transition processes were observed, such as four transition, three transition and two transition in the largest, middle and smallest MTJ ring, respectively. Furthermore, the biasing fields observed from major loops decrease with decreasing size, which may result from edge roughness produced in the ion-milling process

  16. Volume-of-fluid simulations in microfluidic T-junction devices: Influence of viscosity ratio on droplet size

    Science.gov (United States)

    Nekouei, Mehdi; Vanapalli, Siva A.

    2017-03-01

    We used volume-of-fluid (VOF) method to perform three-dimensional numerical simulations of droplet formation of Newtonian fluids in microfluidic T-junction devices. To evaluate the performance of the VOF method we examined the regimes of drop formation and determined droplet size as a function of system parameters. Comparison of the simulation results with four sets of experimental data from the literature showed good agreement, validating the VOF method. Motivated by the lack of adequate studies investigating the influence of viscosity ratio (λ) on the generated droplet size, we mapped the dependence of drop volume on capillary number (0.001 1. In addition, we find that at a given capillary number, the size of droplets does not vary appreciably when λ 1. We develop an analytical model for predicting the droplet size that includes a viscosity-dependent breakup time for the dispersed phase. This improved model successfully predicts the effects of the viscosity ratio observed in simulations. Results from this study are useful for the design of lab-on-chip technologies and manufacture of microfluidic emulsions, where there is a need to know how system parameters influence the droplet size.

  17. Functional roles of the amino terminal domain in determining biophysical properties of Cx50 gap junction channels

    Directory of Open Access Journals (Sweden)

    Li eXin

    2013-12-01

    Full Text Available Communication through gap junction channels is essential for synchronized and coordinated cellular activities. The gap junction channel pore size, its switch control for opening/closing, and the modulations by chemicals can be different depending on the connexin subtypes that compose the channel. Recent structural and functional studies provide compelling evidence that the amino terminal (NT domains of several connexins line the pore of gap junction channels and play an important role in single channel conductance (γj and transjunctional voltage-dependent gating (Vj-gating. This article reviews recent studies conducted on a series of mutations/chimeras in the NT domain of connexin50 (Cx50. Functional examination of the gap junction channels formed by these mutants/chimeras shows the net charge number at the NT domain to be an important factor in γj and in Vj-gating. Furthermore, with an increase in the net negative charge at the NT domain, we observed an increase in the γj, as well as changes in the parameters of the Boltzmann fit of the normalized steady-state conductance and Vj relationship. Our data are consistent with a structural model where the NT domain of Cx50 lines the gap junction pore and plays an important role in sensing Vj and in the subsequent conformational changes leading to gating, as well as in limiting the rate of ion permeation.

  18. Overvalue relative renal function in unilateral ureteropelvic junction obstruction?

    International Nuclear Information System (INIS)

    Baquedano, P.; Orellana, P.; Varas, J.

    2002-01-01

    Introduction: Relative renal function (RRF) is used as an important parameter in the surgical decision of hydronephrosis. In addition, the presence of a supranormal RRF (RRF > 55%) in the hydronephrotic kidney had been recognized. However, this over estimation is, in our experience, not only present with a RRF over 55%. We evaluated demographic data, ultrasonographic finding, age of surgery, presentation (antenatal diagnosis vs postnatal clinical symptoms) in children with unilateral hydronephrosis and a RRF which decreased after surgery. Materials and Methods: Of a series of 66 patients with unilateral ureteropyelic junction obstruction (UPJ) obstruction consecutively operated and followed in the Pediatric Urology unit of Catholic University of Chile, we analyzed 8 cases (12%) in which the relative renal function quantified by diuretic renography with Tc99 MAG3 decreased during follow-up after surgery, over 10% of the baseline value; 6 to 12 months post pyeloplasty, 7 boys, 6 cases with UPJ obstruction of the left side. 3 cases were diagnosed by prenatal ultrasound, 1 by abdominal mass, 1 by urinary tract infection, 1 by abdominal pain and 2 by screening. The age at the time of the surgery was in 4 cases 1 month of life, in two children between 6 and 12 months of age, one boy was 2.4 year old and another one was 7.3 year old. All were considered as a severe hydronefrosis in the ultrasound and 4 cases had a severe atrophy of renal parenchyma. The initial RRF of these cases varied from 35% to 62%. In half of the cases the initial RRF was considered normal, in 2 cases was abnormal ( 55%). In all of these children the RRF decreased after surgery in an average of 35% (28%-54%) of the initial RRF, none of these patients had a normal RRF after surgery. There was no differences in clinical presentation and radiological findings among them. However, it is worth to mention that the symptomatic presentation (pain, abdominal mass) was more frequent in this group that in our

  19. Size dependence of spin-torque induced magnetic switching in CoFeB-based perpendicular magnetization tunnel junctions (invited)

    Science.gov (United States)

    Sun, J. Z.; Trouilloud, P. L.; Gajek, M. J.; Nowak, J.; Robertazzi, R. P.; Hu, G.; Abraham, D. W.; Gaidis, M. C.; Brown, S. L.; O'Sullivan, E. J.; Gallagher, W. J.; Worledge, D. C.

    2012-04-01

    CoFeB-based magnetic tunnel junctions with perpendicular magnetic anisotropy are used as a model system for studies of size dependence in spin-torque-induced magnetic switching. For integrated solid-state memory applications, it is important to understand the magnetic and electrical characteristics of these magnetic tunnel junctions as they scale with tunnel junction size. Size-dependent magnetic anisotropy energy, switching voltage, apparent damping, and anisotropy field are systematically compared for devices with different materials and fabrication treatments. Results reveal the presence of sub-volume thermal fluctuation and reversal, with a characteristic length-scale of the order of approximately 40 nm, depending on the strength of the perpendicular magnetic anisotropy and exchange stiffness. To have the best spin-torque switching efficiency and best stability against thermal activation, it is desirable to optimize the perpendicular anisotropy strength with the junction size for intended use. It also is important to ensure strong exchange-stiffness across the magnetic thin film. These combine to give an exchange length that is comparable or larger than the lateral device size for efficient spin-torque switching.

  20. Effect of the critical current density and the junction size on the leakage current of Nb/Al-AlOx/Nb superconducting tunnel junctions for radiation detection

    International Nuclear Information System (INIS)

    Joosse, K.; Nakagawa, Hiroshi; Akoh, Hiroshi; Takada, Susumu; Maehata, Keisuke; Ishibashi, Kenji.

    1996-01-01

    Nb/Al-AlO x /Nb superconducting tunnel junctions (STJ's) designed for X-ray detection have been fabricated. The behavior of the low-temperature subgap leakage current, which severely limits the energy resolution obtained in such devices, is investigated. From trends in the dependence of the leakage currents on the critical current density and the size of the STJ, as well as from the low-temperature current-voltage characteristics, and an analysis of the base electrode surface morphology, it is concluded that physical defects in the barrier region are the most probable cause of the leakage currents. Suggestions are given for optimization of the device processing. (author)

  1. Oncostatin M induces upregulation of claudin-2 in rodent hepatocytes coinciding with changes in morphology and function of tight junctions

    International Nuclear Information System (INIS)

    Imamura, Masafumi; Kojima, Takashi; Lan, Mengdong; Son, Seiichi; Murata, Masaki; Osanai, Makoto; Chiba, Hideki; Hirata, Koichi; Sawada, Norimasa

    2007-01-01

    In rodent livers, integral tight junction (TJ) proteins claudin-1, -2, -3, -5 and -14 are detected and play crucial roles in the barrier to keep bile in bile canaculi away from the blood circulation. Claudin-2 shows a lobular gradient increasing from periportal to pericentral hepatocytes, whereas claudin-1 and -3 are expressed in the whole liver lobule. Although claudin-2 expression induces cation-selective channels in tight junctions of epithelial cells, the physiological functions and regulation of claudin-2 in hepatocytes remain unclear. Oncostatin M (OSM) is a multifunctional cytokine implicated in the differentiation of hepatocytes that induces formation of E-cadherin-based adherens junctions in fetal hepatocytes. In this study, we examined whether OSM could induce expression and function of claudin-2 in rodent hepatocytes, immortalized mouse and primary cultured proliferative rat hepatocytes. In the immortalized mouse and primary cultured proliferative rat hepatocytes, treatment with OSM markedly increased mRNA and protein of claudin-2 together with formation of developed networks of TJ strands. The increase of claudin-2 enhanced the paracellular barrier function which depended on molecular size. The increase of claudin-2 expression induced by OSM in rodent hepatocytes was regulated through distinct signaling pathways including PKC. These results suggest that expression of claudin-2 in rodent hepatocytes may play a specific role as controlling the size of paracellular permeability in the barrier to keep bile in bile canaculi

  2. Electronic noise of superconducting tunnel junction detectors

    International Nuclear Information System (INIS)

    Jochum, J.; Kraus, H.; Gutsche, M.; Kemmather, B.; Feilitzsch, F. v.; Moessbauer, R.L.

    1994-01-01

    The optimal signal to noise ratio for detectors based on superconducting tunnel junctions is calculated and compared for the cases of a detector consisting of one single tunnel junction, as well as of series and of parallel connections of such tunnel junctions. The influence of 1 / f noise and its dependence on the dynamical resistance of tunnel junctions is discussed quantitatively. A single tunnel junction yields the minimum equivalent noise charge. Such a tunnel junction exhibits the best signal to noise ratio if the signal charge is independent of detector size. In case, signal charge increases with detector size, a parallel or a series connection of tunnel junctions would provide the optimum signal to noise ratio. The equivalent noise charge and the respective signal to noise ratio are deduced as functions of tunnel junction parameters such as tunneling time, quasiparticle lifetime, etc. (orig.)

  3. Mixing at double-Tee junctions with unequal pipe sizes in water distribution systems

    Data.gov (United States)

    U.S. Environmental Protection Agency — Pipe flow mixing with various solute concentrations and flow rates at pipe junctions is investigated. The degree of mixing affects the spread of contaminants in a...

  4. Tight junction-associated MARVEL proteins marveld3, tricellulin, and occludin have distinct but overlapping functions.

    Science.gov (United States)

    Raleigh, David R; Marchiando, Amanda M; Zhang, Yong; Shen, Le; Sasaki, Hiroyuki; Wang, Yingmin; Long, Manyuan; Turner, Jerrold R

    2010-04-01

    In vitro studies have demonstrated that occludin and tricellulin are important for tight junction barrier function, but in vivo data suggest that loss of these proteins can be overcome. The presence of a heretofore unknown, yet related, protein could explain these observations. Here, we report marvelD3, a novel tight junction protein that, like occludin and tricellulin, contains a conserved four-transmembrane MARVEL (MAL and related proteins for vesicle trafficking and membrane link) domain. Phylogenetic tree reconstruction; analysis of RNA and protein tissue distribution; immunofluorescent and electron microscopic examination of subcellular localization; characterization of intracellular trafficking, protein interactions, dynamic behavior, and siRNA knockdown effects; and description of remodeling after in vivo immune activation show that marvelD3, occludin, and tricellulin have distinct but overlapping functions at the tight junction. Although marvelD3 is able to partially compensate for occludin or tricellulin loss, it cannot fully restore function. We conclude that marvelD3, occludin, and tricellulin define the tight junction-associated MARVEL protein family. The data further suggest that these proteins are best considered as a group with both redundant and unique contributions to epithelial function and tight junction regulation.

  5. Large thermoelectric efficiency of doped polythiophene junction: A density functional study

    Science.gov (United States)

    Golsanamlou, Zahra; Bagheri Tagani, Meysam; Rahimpour Soleimani, Hamid

    2018-06-01

    The thermoelectric properties of polythiophene (PT) coupled to the Au (111) electrodes are studied based on density functional theory with nonequilibrium Green function formalism. Specially, the effect of Li and Cl adsorbents on the thermoelectric efficiency of the PT junction is investigated in different concentrations of the dopants for two lengths of the PT. Results show that the presence of dopants can bring the structural changes in the oligomer and modify the arrangement of the molecular levels leading to the dramatic changes in the transmission spectra of the junction. Therefore, the large enhancement in thermopower and consequently figure of merit is obtained by dopants which makes the doped PT junction as a beneficial thermoelectric device.

  6. Gap junctions in cells of the immune system: structure, regulation and possible functional roles

    Directory of Open Access Journals (Sweden)

    J.C. Sáez

    2000-04-01

    Full Text Available Gap junction channels are sites of cytoplasmic communication between contacting cells. In vertebrates, they consist of protein subunits denoted connexins (Cxs which are encoded by a gene family. According to their Cx composition, gap junction channels show different gating and permeability properties that define which ions and small molecules permeate them. Differences in Cx primary sequences suggest that channels composed of different Cxs are regulated differentially by intracellular pathways under specific physiological conditions. Functional roles of gap junction channels could be defined by the relative importance of permeant substances, resulting in coordination of electrical and/or metabolic cellular responses. Cells of the native and specific immune systems establish transient homo- and heterocellular contacts at various steps of the immune response. Morphological and functional studies reported during the last three decades have revealed that many intercellular contacts between cells in the immune response present gap junctions or "gap junction-like" structures. Partial characterization of the molecular composition of some of these plasma membrane structures and regulatory mechanisms that control them have been published recently. Studies designed to elucidate their physiological roles suggest that they might permit coordination of cellular events which favor the effective and timely response of the immune system.

  7. Interfering amino terminal peptides and functional implications for heteromeric gap junction formation

    Directory of Open Access Journals (Sweden)

    Richard David Veenstra

    2013-05-01

    Full Text Available Connexin43 (Cx43 is widely expressed in many different tissues of the human body. In cells of some organs, Cx43 is co-expressed with other connexins (Cx, including Cx46 and Cx50 in lens, Cx40 in atrium, Purkinje fibers, and the blood vessel wall, Cx45 in heart, and Cx37 in the ovary. Interactions with the co-expressed connexins may have profound functional implications. The abilities of Cx37, Cx45, Cx46, and Cx50 to function in heteromeric gap junction combinations with Cx43 are well documented. Different studies disagree regarding the ability of Cx43 and Cx40 to produce functional heteromeric gap junctions with each other. We review previous studies regarding the heteromeric interactions of Cx43. The possibility of negative functional interactions between the cytoplasmic pore-forming amino terminal (NT domains of these connexins was assessed using pentameric connexin sequence-specific NT domain (iNT peptides applied to cells expressing homomeric Cx40, Cx37, Cx45, Cx46, and Cx50 gap junctions. A Cx43 iNT peptide corresponding to amino acids 9 to 13 (Ac-KLLDK-NH2 specifically inhibited the electrical coupling of Cx40 gap junctions in a transjunctional (Vj voltage-dependent manner without affecting the function of homologous Cx37, Cx46, Cx50, and Cx45 gap junctions. A Cx40 iNT (Ac-EFLEE-OH peptide counteracted the Vj-dependent block of Cx40 gap junctions, whereas a similarly charged Cx50 iNT (Ac-EEVNE-OH peptide did not, suggesting that these NT domain interactions are not solely based on electrostatics. These data are consistent with functional Cx43 heteromeric gap junction formation with Cx37, Cx45, Cx46, and Cx50 and suggest that Cx40 uniquely experiences functional suppressive interactions with a Cx43 NT domain sequence. These findings present unique functional implications about the heteromeric interactions between Cx43 and Cx40 that may influence cardiac conduction in atrial myocardium and the specialized conduction system.

  8. Rectified tunneling current response of bio-functionalized metal-bridge-metal junctions.

    Science.gov (United States)

    Liu, Yaqing; Offenhäusser, Andreas; Mayer, Dirk

    2010-01-15

    Biomolecular bridged nanostructures allow direct electrical addressing of electroactive biomolecules, which is of interest for the development of bioelectronic and biosensing hybrid junctions. In the present paper, the electroactive biomolecule microperoxidase-11 (MP-11) was integrated into metal-bridge-metal (MBM) junctions assembled from a scanning tunneling microscope (STM) setup. Before immobilization of MP-11, the Au working electrode was first modified by a self-assembled monolayer of 1-undecanethiol (UDT). A symmetric and potential independent response of current-bias voltage (I(t)/V(b)) was observed for the Au (substrate)/UDT/Au (tip) junction. However, the I(t)/V(b) characteristics became potential dependent and asymmetrical after binding of MP-11 between the electrodes of the junction. The rectification ratio of the asymmetric current response varies with gate electrode modulation. A resonant tunneling process between metal electrode and MP-11 enhances the tunneling current and is responsible for the observed rectification. Our investigations demonstrated that functional building blocks of proteins can be reassembled into new conceptual devices with operation modes deviating from their native function, which could prove highly useful in the design of future biosensors and bioelectronic devices. Copyright 2009 Elsevier B.V. All rights reserved.

  9. Gap Junctions

    Science.gov (United States)

    Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L.; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

    2013-01-01

    Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1981-2035, 2012. PMID:23723031

  10. Quantum size effects on spin-transfer torque in a double barrier magnetic tunnel junction with a nonmagnetic-metal (semiconductor) spacer

    International Nuclear Information System (INIS)

    Daqiq, Reza; Ghobadi, Nader

    2016-01-01

    We study the quantum size effects of an MgO-based double barrier magnetic tunnel junction with a nonmagnetic-metal (DBMTJ-NM) (semiconductor (DBMTJ-SC)) spacer on the charge current and the spin-transfer torque (STT) components using non-equilibrium Green's function (NEGF) formalism. The results show oscillatory behavior due to the resonant tunneling effect depending on the structure parameters. We find that the charge current and the STT components in the DBMTJ-SC demonstrate the magnitude enhancement in comparison with the DBMTJ-NM. The bias dependence of the STT components in a DBMTJ-NM shows different behavior in comparison with spin valves and conventional MTJs. Therefore, by choosing a specific SC spacer with suitable thickness in a DBMTJ the charge current and the STT components significantly increase so that one can design a device with high STT and faster magnetization switching. - Highlights: • The quantum size effects are studied in double barrier magnetic tunnel junctions. • Spin torque (ST) components oscillate for increasing of middle spacer thicknesses. • Due to the resonant tunneling in the quantum well, oscillations have appeared. • By replacement a metal spacer with a semiconductor (ZnO) ST has increased. • The ST components vs. bias show gradually decreasing unlike spin valves or MTJs.

  11. Quantum size effects on spin-transfer torque in a double barrier magnetic tunnel junction with a nonmagnetic-metal (semiconductor) spacer

    Energy Technology Data Exchange (ETDEWEB)

    Daqiq, Reza; Ghobadi, Nader

    2016-07-15

    We study the quantum size effects of an MgO-based double barrier magnetic tunnel junction with a nonmagnetic-metal (DBMTJ-NM) (semiconductor (DBMTJ-SC)) spacer on the charge current and the spin-transfer torque (STT) components using non-equilibrium Green's function (NEGF) formalism. The results show oscillatory behavior due to the resonant tunneling effect depending on the structure parameters. We find that the charge current and the STT components in the DBMTJ-SC demonstrate the magnitude enhancement in comparison with the DBMTJ-NM. The bias dependence of the STT components in a DBMTJ-NM shows different behavior in comparison with spin valves and conventional MTJs. Therefore, by choosing a specific SC spacer with suitable thickness in a DBMTJ the charge current and the STT components significantly increase so that one can design a device with high STT and faster magnetization switching. - Highlights: • The quantum size effects are studied in double barrier magnetic tunnel junctions. • Spin torque (ST) components oscillate for increasing of middle spacer thicknesses. • Due to the resonant tunneling in the quantum well, oscillations have appeared. • By replacement a metal spacer with a semiconductor (ZnO) ST has increased. • The ST components vs. bias show gradually decreasing unlike spin valves or MTJs.

  12. Firm size diversity, functional richness, and resilience

    Science.gov (United States)

    Garmestani, A.S.; Allen, Craig R.; Mittelstaedt, J.D.; Stow, C.A.; Ward, W.A.

    2006-01-01

    This paper applies recent advances in ecology to our understanding of firm development, sustainability, and economic development. The ecological literature indicates that the greater the functional richness of species in a system, the greater its resilience - that is, its ability to persist in the face of substantial changes in the environment. This paper focuses on the effects of functional richness across firm size on the ability of industries to survive in the face of economic change. Our results indicate that industries with a richness of industrial functions are more resilient to employment volatility. ?? 2006 Cambridge University Press.

  13. Modulation of Tight Junction Structure and Function by Kinases and Phosphatases Targeting Occludin

    Directory of Open Access Journals (Sweden)

    Max Johannes Dörfel

    2012-01-01

    Full Text Available Tight junctions (TJs typically represent the most apical contacts in epithelial and endothelial cell layers where they play an essential role in the separation of extracellular or luminal spaces from underlying tissues in the body. Depending on the protein composition, TJs define the barrier characteristics and in addition maintain cell polarity. Two major families of integral membrane proteins form the typical TJ strand network, the tight junction-associated MARVEL protein (TAMP family members occludin, tricellulin, and MarvelD3 as well as a specific set of claudins. Occludin was the first identified member of these tetraspanins and is now widely accepted as a regulator of TJ assembly and function. Therefore, occludin itself has to be tightly regulated. Phosphorylation of occludin appears to be of central importance in this context. Here we want to summarize current knowledge on the kinases and phosphatases directly modifying occludin, and their role in the regulation of TJ structure, function, and dynamics.

  14. Prediction of chaos in a Josephson junction by the Melnikov-function technique

    DEFF Research Database (Denmark)

    Bartuccelli, M.; Christiansen, Peter Leth; Pedersen, Niels Falsig

    1986-01-01

    The Melnikov function for prediction of Smale horseshoe chaos is applied to the rf-driven Josephson junction. Linear and quadratic damping resistors are considered. In the latter case the analytic solution including damping and dc bias is used to obtain an improved threshold curve for the onset...... of chaos. The prediction is compared to new computational solutions. The Melnikov technique provides a good, but slightly low, estimate of the chaos threshold....

  15. The caecocolonic junction in humans has a sphincteric anatomy and function.

    Science.gov (United States)

    Faussone Pellegrini, M S; Manneschi, L I; Manneschi, L

    1995-01-01

    Sphincteric anatomy and function are present at the caecocolonic junction in several mammals. In humans, radiologists and endoscopists have respectively reported a circumferential contraction and a prominent ileocaecal fold at the border area between the caecum and the ascending colon. Anatomical findings on necropsy material failed to confirm its presence. Microscopic studies on surgical specimens showed the existence of muscular and innervational patterns different from those of adjacent areas. The aim of this work was to confirm the existence of a specialised fold at the caecocolonic junction in humans and to ascertain its role by carrying out a study of functional anatomy. Pancolonoscopies were performed on 100 patients and ileocaecal fold behaviour was observed before and after mechanical stimulation. Isolated ileocaecocolonic regions, surgically obtained, were filled with a fixative solution to study their macro and microscopic morphology after stimulation. Endoscopically, the ileocaecal fold was semilunar or circular in shape and spontaneous or evoked spasms occurred in 52 patients. A prominent circular fold could be seen in surgical specimens after stimulation. The entire muscle coat deeply penetrated this fold, showing the features characteristic of the ileocaecal junction. In particular, the inner portion of the circular muscle showed a peculiar arrangement and was thicker than elsewhere. These results show that in humans the caecocolonic junction is provided with a sphincter morphology and function. Little is known about its physiological relevance in ileal flow accommodation and caecal filling and emptying but it should not be underestimated with regard to some colonic motility disorders. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 PMID:7489934

  16. A new spin-functional MOSFET based on magnetic tunnel junction technology: pseudo-spin-MOSFET

    OpenAIRE

    Shuto, Yusuke; Nakane, Ryosho; Wang, Wenhong; Sukegawa, Hiroaki; Yamamoto, Shuu'ichirou; Tanaka, Masaaki; Inomata, Koichiro; Sugahara, Satoshi

    2009-01-01

    We fabricated and characterized a new spin-functional MOSFET referred to as a pseudo-spin-MOSFET (PS-MOSFET). The PS-MOSFET is a circuit using an ordinary MOSFET and magnetic tunnel junction (MTJ) for reproducing functions of spin-transistors. Device integration techniques for a bottom gate MOSFET using a silicon-on-insulator (SOI) substrate and for an MTJ with a full-Heusler alloy electrode and MgO tunnel barrier were developed. The fabricated PS-MOSFET exhibited high and low transconductanc...

  17. Comparative study of size dependent four-point probe sheet resistance measurement on laser annealed ultra-shallow junctions

    DEFF Research Database (Denmark)

    Petersen, Dirch Hjorth; Lin, Rong; Hansen, Torben Mikael

    2008-01-01

    have been used to characterize the sheet resistance uniformity of millisecond laser annealed USJs. They verify, both experimentally and theoretically, that the probe pitch of a four-point probe can strongly affect the measured sheet resistance. Such effect arises from the sensitivity (or "spot size......In this comparative study, the authors demonstrate the relationship/correlation between macroscopic and microscopic four-point sheet resistance measurements on laser annealed ultra-shallow junctions (USJs). Microfabricated cantilever four-point probes with probe pitch ranging from 1.5 to 500 mu m......") of an in-line four-point probe. Their study shows the benefit of the spatial resolution of the micro four-point probe technique to characterize stitching effects resulting from the laser annealing process....

  18. Claudin Loss-of-Function Disrupts Tight Junctions and Impairs Amelogenesis.

    Science.gov (United States)

    Bardet, Claire; Ribes, Sandy; Wu, Yong; Diallo, Mamadou Tidiane; Salmon, Benjamin; Breiderhoff, Tilman; Houillier, Pascal; Müller, Dominik; Chaussain, Catherine

    2017-01-01

    Claudins are a family of proteins that forms paracellular barriers and pores determining tight junctions (TJ) permeability. Claudin-16 and -19 are pore forming TJ proteins allowing calcium and magnesium reabsorption in the thick ascending limb of Henle's loop (TAL). Loss-of-function mutations in the encoding genes, initially identified to cause Familial Hypomagnesemia with Hypercalciuria and Nephrocalcinosis (FHHNC), were recently shown to be also involved in Amelogenesis Imperfecta (AI). In addition, both claudins were expressed in the murine tooth germ and Claudin-16 knockout (KO) mice displayed abnormal enamel formation. Claudin-3, an ubiquitous claudin expressed in epithelia including kidney, acts as a barrier-forming tight junction protein. We determined that, similarly to claudin-16 and claudin-19, claudin-3 was expressed in the tooth germ, more precisely in the TJ located at the apical end of secretory ameloblasts. The observation of Claudin-3 KO teeth revealed enamel defects associated to impaired TJ structure at the secretory ends of ameloblasts and accumulation of matrix proteins in the forming enamel. Thus, claudin-3 protein loss-of-function disturbs amelogenesis similarly to claudin-16 loss-of-function, highlighting the importance of claudin proteins for the TJ structure. These findings unravel that loss-of-function of either pore or barrier-forming TJ proteins leads to enamel defects. Hence, the major structural function of claudin proteins appears essential for amelogenesis.

  19. Claudin Loss-of-Function Disrupts Tight Junctions and Impairs Amelogenesis

    Directory of Open Access Journals (Sweden)

    Claire Bardet

    2017-05-01

    Full Text Available Claudins are a family of proteins that forms paracellular barriers and pores determining tight junctions (TJ permeability. Claudin-16 and -19 are pore forming TJ proteins allowing calcium and magnesium reabsorption in the thick ascending limb of Henle's loop (TAL. Loss-of-function mutations in the encoding genes, initially identified to cause Familial Hypomagnesemia with Hypercalciuria and Nephrocalcinosis (FHHNC, were recently shown to be also involved in Amelogenesis Imperfecta (AI. In addition, both claudins were expressed in the murine tooth germ and Claudin-16 knockout (KO mice displayed abnormal enamel formation. Claudin-3, an ubiquitous claudin expressed in epithelia including kidney, acts as a barrier-forming tight junction protein. We determined that, similarly to claudin-16 and claudin-19, claudin-3 was expressed in the tooth germ, more precisely in the TJ located at the apical end of secretory ameloblasts. The observation of Claudin-3 KO teeth revealed enamel defects associated to impaired TJ structure at the secretory ends of ameloblasts and accumulation of matrix proteins in the forming enamel. Thus, claudin-3 protein loss-of-function disturbs amelogenesis similarly to claudin-16 loss-of-function, highlighting the importance of claudin proteins for the TJ structure. These findings unravel that loss-of-function of either pore or barrier-forming TJ proteins leads to enamel defects. Hence, the major structural function of claudin proteins appears essential for amelogenesis.

  20. Nanoscale E-Cadherin ligand patterns show threshold size for cellular adhesion and adherence junction formation

    DEFF Research Database (Denmark)

    Kristensen, Stine H; Pedersen, Gitte Albinus; Nejsum, Lene Niemann

    2012-01-01

    The role of ligand spatial distribution on the formation of cadherin mediated cell-cell contacts is studied utilizing nanopatterns of E-cadherin ligands. Protein patches ranging in size from 100 nm to 800 nm prepared by colloidal lithography critically influence adhesion, spreading and formation ...

  1. Two-phase flow patterns and size distribution of droplets in a microfluidic T-junction: Experimental observations in the squeezing regime

    Science.gov (United States)

    Mahdi, Yassine; Daoud, Kamel; Tadrist, Lounès

    2017-04-01

    Generating micrometer sized droplets has been studied in a microfluidic system with T-junction geometry 250 μm in internal diameter and with PTFE capillary tubing. Several experiments were conducted by varying the flow rate of the dispersed phase from 2.78 ṡ10-11 m3 /s to 5.28 ṡ10-9 m3 /s and that of the continuous phase from 2.78 ṡ10-10 m3 /s to 1.94 ṡ10-9 m3 /s. The visualization of different flow regimes (drop, plug, and annular) was carried out for three configurations (not inverted in a horizontal position, inverted in a horizontal position, and inverted in a vertical position) for low capillary numbers. The model of Gauss was also chosen for a droplet size distribution in the dispersed phase, with the flow quality x varying from 0.016 to 0.44. The evolution of the drop size distribution as a function of the flow quality in the dispersed phase shows that the variation coefficient of the droplet's diameter is inversely proportional to the flow quality.

  2. Fabrication of nano-sized magnetic tunnel junctions using lift-off process assisted by atomic force probe tip.

    Science.gov (United States)

    Jung, Ku Youl; Min, Byoung-Chul; Ahn, Chiyui; Choi, Gyung-Min; Shin, Il-Jae; Park, Seung-Young; Rhie, Kungwon; Shin, Kyung-Ho

    2013-09-01

    We present a fabrication method for nano-scale magnetic tunnel junctions (MTJs), employing e-beam lithography and lift-off process assisted by the probe tip of atomic force microscope (AFM). It is challenging to fabricate nano-sized MTJs on small substrates because it is difficult to use chemical mechanical planarization (CMP) process. The AFM-assisted lift-off process enables us to fabricate nano-sized MTJs on small substrates (12.5 mm x 12.5 mm) without CMP process. The e-beam patterning has been done using bi-layer resist, the poly methyl methacrylate (PMMA)/ hydrogen silsesquioxane (HSQ). The PMMA/HSQ resist patterns are used for both the etch mask for ion milling and the self-aligned mask for top contact formation after passivation. The self-aligned mask buried inside a passivation oxide layer, is readily lifted-off by the force exerted by the probe tip. The nano-MTJs (160 nm x 90 nm) fabricated by this method show clear current-induced magnetization switching with a reasonable TMR and critical switching current density.

  3. Claudin-11 and occludin are major contributors to Sertoli cell tight junction function, in vitro

    Directory of Open Access Journals (Sweden)

    Mark J McCabe

    2016-01-01

    Full Text Available The Sertoli cell tight junction (TJ is the key component of the blood-testis barrier, where it sequesters developing germ cells undergoing spermatogenesis within the seminiferous tubules. Hormonally regulated claudin-11 is a critical transmembrane protein involved in barrier function and its murine knockout results in infertility. We aimed to assess quantitatively the significance of the contribution of claudin-11 to TJ function, in vitro, using siRNA-mediated gene silencing. We also conducted an analysis of the contribution of occludin, another intrinsic transmembrane protein of the TJ. Silencing of claudin-11 and/or occludin was conducted using siRNA in an immature rat Sertoli cell culture model. Transepithelial electrical resistance was used to assess quantitatively TJ function throughout the culture. Two days after siRNA treatment, cells were fixed for immunocytochemical localization of junction proteins or lyzed for RT-PCR assessment of mRNA expression. Silencing of claudin-11, occludin, or both resulted in significant decreases in TJ function of 55% (P < 0.01, 51% (P < 0.01, and 62% (P < 0.01, respectively. Data were concomitant with significant decreases in mRNA expression and marked reductions in the localization of targeted proteins to the Sertoli cell TJ. We provide quantitative evidence that claudin-11 contributes significantly (P < 0.01 to Sertoli cell TJ function in vitro. Interestingly, occludin, which is hormonally regulated but not implicated in infertility until late adulthood, is also a significant (P < 0.01 contributor to barrier function. Our data are consistent with in vivo studies that clearly demonstrate a role for these proteins in maintaining normal TJ barrier structure and function.

  4. Energy level alignment and quantum conductance of functionalized metal-molecule junctions

    DEFF Research Database (Denmark)

    Jin, Chengjun; Strange, Mikkel; Markussen, Troels

    2013-01-01

    We study the effect of functional groups (CH3*4, OCH3, CH3, Cl, CN, F*4) on the electronic transport properties of 1,4-benzenediamine molecular junctions using the non-equilibrium Green function method. Exchange and correlation effects are included at various levels of theory, namely density...... functional theory (DFT), energy level-corrected DFT (DFT+Σ), Hartree-Fock and the many-body GW approximation. All methods reproduce the expected trends for the energy of the frontier orbitals according to the electron donating or withdrawing character of the substituent group. However, only the GW method...... predicts the correct ordering of the conductance amongst the molecules. The absolute GW (DFT) conductance is within a factor of two (three) of the experimental values. Correcting the DFT orbital energies by a simple physically motivated scissors operator, Σ, can bring the DFT conductances close...

  5. Intestinal epithelial barrier function and tight junction proteins with heat and exercise

    DEFF Research Database (Denmark)

    Dokladny, Karol; Zuhl, Micah N; Moseley, Pope L

    2016-01-01

    A single layer of enterocytes and tight junctions (intercellular multiprotein complexes) form the intestinal epithelial barrier that controls transport of molecules through transcellular and paracellular pathways. A dysfunctional or "leaky" intestinal tight junction barrier allows augmented perme...

  6. Regulation of gap junction function and Connexin 43 expression by cytochrome P450 oxidoreductase (CYPOR)

    International Nuclear Information System (INIS)

    Polusani, Srikanth R.; Kar, Rekha; Riquelme, Manuel A.; Masters, Bettie Sue; Panda, Satya P.

    2011-01-01

    Highlights: → Humans with severe forms of cytochrome P450 oxidoreductase (CYPOR) mutations show bone defects as observed in Antley-Bixler Syndrome. → First report showing knockdown of CYPOR in osteoblasts decreased Connexin 43 (Cx43) protein levels. Cx43 is known to play an important role in bone modeling. → Knockdown of CYPOR decreased Gap Junctional Intercellular Communication and hemichannel activity. → Knockdown of CYPOR decreased Cx43 in mouse primary calvarial osteoblasts. → Decreased Cx43 expression was observed at the transcriptional level. -- Abstract: Cytochrome P450 oxidoreductase (CYPOR) is a microsomal electron-transferring enzyme containing both FAD and FMN as co-factors, which provides the reducing equivalents to various redox partners, such as cytochromes P450 (CYPs), heme oxygenase (HO), cytochrome b 5 and squalene monooxygenase. Human patients with severe forms of CYPOR mutation show bone defects such as cranio- and humeroradial synostoses and long bone fractures, known as Antley-Bixler-like Syndrome (ABS). To elucidate the role of CYPOR in bone, we knocked-down CYPOR in multiple osteoblast cell lines using RNAi technology. In this study, knock-down of CYPOR decreased the expression of Connexin 43 (Cx43), known to play a critical role in bone formation, modeling, and remodeling. Knock-down of CYPOR also decreased Gap Junction Intercellular Communication (GJIC) and hemichannel activity. Promoter luciferase assays revealed that the decrease in expression of Cx43 in CYPOR knock-down cells was due to transcriptional repression. Primary osteoblasts isolated from bone specific Por knock-down mice calvariae confirmed the findings in the cell lines. Taken together, our study provides novel insights into the regulation of gap junction function by CYPOR and suggests that Cx43 may play an important role(s) in CYPOR-mediated bone defects seen in patients.

  7. Regulation of gap junction function and Connexin 43 expression by cytochrome P450 oxidoreductase (CYPOR)

    Energy Technology Data Exchange (ETDEWEB)

    Polusani, Srikanth R.; Kar, Rekha; Riquelme, Manuel A.; Masters, Bettie Sue [The University of Texas Health Science Center at San Antonio, Department of Biochemistry, San Antonio, TX 78229 (United States); Panda, Satya P., E-mail: panda@uthscsa.edu [The University of Texas Health Science Center at San Antonio, Department of Biochemistry, San Antonio, TX 78229 (United States)

    2011-08-05

    Highlights: {yields} Humans with severe forms of cytochrome P450 oxidoreductase (CYPOR) mutations show bone defects as observed in Antley-Bixler Syndrome. {yields} First report showing knockdown of CYPOR in osteoblasts decreased Connexin 43 (Cx43) protein levels. Cx43 is known to play an important role in bone modeling. {yields} Knockdown of CYPOR decreased Gap Junctional Intercellular Communication and hemichannel activity. {yields} Knockdown of CYPOR decreased Cx43 in mouse primary calvarial osteoblasts. {yields} Decreased Cx43 expression was observed at the transcriptional level. -- Abstract: Cytochrome P450 oxidoreductase (CYPOR) is a microsomal electron-transferring enzyme containing both FAD and FMN as co-factors, which provides the reducing equivalents to various redox partners, such as cytochromes P450 (CYPs), heme oxygenase (HO), cytochrome b{sub 5} and squalene monooxygenase. Human patients with severe forms of CYPOR mutation show bone defects such as cranio- and humeroradial synostoses and long bone fractures, known as Antley-Bixler-like Syndrome (ABS). To elucidate the role of CYPOR in bone, we knocked-down CYPOR in multiple osteoblast cell lines using RNAi technology. In this study, knock-down of CYPOR decreased the expression of Connexin 43 (Cx43), known to play a critical role in bone formation, modeling, and remodeling. Knock-down of CYPOR also decreased Gap Junction Intercellular Communication (GJIC) and hemichannel activity. Promoter luciferase assays revealed that the decrease in expression of Cx43 in CYPOR knock-down cells was due to transcriptional repression. Primary osteoblasts isolated from bone specific Por knock-down mice calvariae confirmed the findings in the cell lines. Taken together, our study provides novel insights into the regulation of gap junction function by CYPOR and suggests that Cx43 may play an important role(s) in CYPOR-mediated bone defects seen in patients.

  8. Strain-dependent augmentation of tight-junction barrier function in human primary epidermal keratinocytes by Lactobacillus and Bifidobacterium lysates.

    Science.gov (United States)

    Sultana, Reshma; McBain, Andrew J; O'Neill, Catherine A

    2013-08-01

    In this study, we investigated whether probiotic lysates can modify the tight-junction function of human primary keratinocytes. The keratinocytes were grown on cell culture inserts and treated with lysates from Bifidobacterium longum, Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus fermentum, or Lactobacillus rhamnosus GG. With the exception of L. fermentum (which decreased cell viability), all strains markedly enhanced tight-junction barrier function within 24 h, as assessed by measurements of transepithelial electrical resistance (TEER). However, B. longum and L. rhamnosus GG were the most efficacious, producing dose-dependent increases in resistance that were maintained for 4 days. These increases in TEER correlated with elevated expression of tight-junction protein components. Neutralization of Toll-like receptor 2 abolished both the increase in TEER and expression of tight-junction proteins induced by B. longum, but not L. rhamnosus GG. These data suggest that some bacterial strains increase tight-junction function via modulation of protein components but the different pathways involved may vary depending on the bacterial strain.

  9. Delayed Presentation of Ureteropelvic Junction Obstruction and Loss of Renal Function After Initially Mild (SFU Grade 1-2) Hydronephrosis.

    Science.gov (United States)

    Bowen, Diana K; Yerkes, Elizabeth B; Lindgren, Bruce W; Gong, Edward M; Faasse, Mark A

    2015-07-01

    We report 4 pediatric cases of ureteropelvic junction obstruction involving delayed progression of initially mild postnatal hydronephrosis. All 4 children became symptomatic; however, 3 already had a substantial decrement of ipsilateral kidney function by the time of diagnosis. Two of these 3 patients had previous renal scintigraphy demonstrating normal differential function. We caution that counseling regarding hydronephrosis should emphasize the importance of prompt re-evaluation for any symptoms potentially referable to delayed presentation of ureteropelvic junction obstruction, irrespective of initial hydronephrosis grade. Future studies are needed to determine the optimal follow-up regimen for conservative management of hydronephrosis. Copyright © 2015 Elsevier Inc. All rights reserved.

  10. Dependences of the Tunnel Magnetoresistance and Spin Transfer Torque on the Sizes and Concentration of Nanoparticles in Magnetic Tunnel Junctions

    Science.gov (United States)

    Esmaeili, A. M.; Useinov, A. N.; Useinov, N. Kh.

    2018-01-01

    Dependences of the tunnel magnetoresistance and in-plane component of the spin transfer torque on the applied voltage in a magnetic tunnel junction have been calculated in the approximation of ballistic transport of conduction electrons through an insulating layer with embedded magnetic or nonmagnetic nanoparticles. A single-barrier magnetic tunnel junction with a nanoparticle embedded in an insulator forms a double-barrier magnetic tunnel junction. It has been shown that the in-plane component of the spin transfer torque in the double-barrier magnetic tunnel junction can be higher than that in the single-barrier one at the same thickness of the insulating layer. The calculations show that nanoparticles embedded in the tunnel junction increase the probability of tunneling of electrons, create resonance conditions, and ensure the quantization of the conductance in contrast to the tunnel junction without nanoparticles. The calculated dependences of the tunnel magnetoresistance correspond to experimental data demonstrating peak anomalies and suppression of the maximum magnetoresistances at low voltages.

  11. [Functional connectivity of temporal parietal junction in online game addicts:a resting-state functional magnetic resonance imaging study].

    Science.gov (United States)

    Yuan, Ji; Qian, Ruobing; Lin, Bin; Fu, Xianming; Wei, Xiangpin; Weng, Chuanbo; Niu, Chaoshi; Wang, Yehan

    2014-02-11

    To explore the functions of temporal parietal junction (TPJ) as parts of attention networks in the pathogenesis of online game addiction using resting-state functional magnetic resonance imaging (fMRI). A total of 17 online game addicts (OGA) were recruited as OGA group and 17 healthy controls during the same period were recruited as CON group. The neuropsychological tests were performed for all of them to compare the inter-group differences in the results of Internet Addiction Test (IAT) and attention functions. All fMRI data were preprocessed after resting-state fMRI scanning. Then left and right TPJ were selected as regions of interest (ROIs) to calculate the linear correlation between TPJ and entire brain to compare the inter-group differences. Obvious differences existed between OGA group (71 ± 5 scores) and CON group (19 ± 7 scores) in the IAT results and attention function (P online game addicts showed decreased functional connectivity with bilateral ventromedial prefrontal cortex (VMPFC), bilateral hippocampal gyrus and bilateral amygdaloid nucleus, but increased functional connectivity with right cuneus.However, left TPJ demonstrated decreased functional connectivity with bilateral superior frontal gyrus and bilateral middle frontal gyrus, but increased functional connectivity with bilateral cuneus (P online game addicts.It suggests that TPJ is an important component of attention networks participating in the generation of online game addiction.

  12. Functional connectivity profile of the human inferior frontal junction: involvement in a cognitive control network

    Directory of Open Access Journals (Sweden)

    Sundermann Benedikt

    2012-10-01

    Full Text Available Abstract Background The human inferior frontal junction area (IFJ is critically involved in three main component processes of cognitive control (working memory, task switching and inhibitory control. As it overlaps with several areas in established anatomical labeling schemes, it is considered to be underreported as a functionally distinct location in the neuroimaging literature. While recent studies explicitly focused on the IFJ's anatomical organization and functional role as a single brain area, it is usually not explicitly denominated in studies on cognitive networks. However based on few analyses in small datasets constrained by specific a priori assumptions on its functional specialization, the IFJ has been postulated to be part of a cognitive control network. Goal of this meta-analysis was to establish the IFJ’s connectivity profile on a high formal level of evidence by aggregating published implicit knowledge about its co-activations. We applied meta-analytical connectivity modeling (MACM based on the activation likelihood estimation (ALE method without specific assumptions regarding functional specialization on 180 (reporting left IFJ activity and 131 (right IFJ published functional neuroimaging experiments derived from the BrainMap database. This method is based on coordinates in stereotaxic space, not on anatomical descriptors. Results The IFJ is significantly co-activated with areas in the dorsolateral and ventrolateral prefrontal cortex, anterior insula, medial frontal gyrus / pre-SMA, posterior parietal cortex, occipitotemporal junction / cerebellum, thalamus and putamen as well as language and motor areas. Results are corroborated by an independent resting-state fMRI analysis. Conclusions These results support the assumption that the IFJ is part of a previously described cognitive control network. They also highlight the involvement of subcortical structures in this system. A direct line is drawn from works on the functional

  13. Could tight junctions regulate the barrier function of the aged skin?

    Science.gov (United States)

    Svoboda, Marek; Bílková, Zuzana; Muthný, Tomáš

    2016-03-01

    The skin is known to be the largest organ in human organism creating interface with outer environment. The skin provides protective barrier against pathogens, physical and chemical insults, and against uncontrolled loss of water. The barrier function was primarily attributed to the stratum corneum (SC) but recent studies confirmed that epidermal tight junctions (TJs) also play important role in maintaining barrier properties of the skin. Independent observations indicate that barrier function and its recovery is impaired in aged skin. However, trans-epidermal water loss (TEWL) values remains rather unchanged in elderly population. UV radiation as major factor of photoageing impairs TJ proteins, but TJs have great self-regenerative potential. Since it may be possible that TJs can compensate TEWL in elderly due to its regenerative and compensatory capabilities, important question remains to be answered: how are TJs regulated during skin ageing? This review provides an insight into TJs functioning as epidermal barrier and summarizes current knowledge about the impact of ageing on the barrier function of the skin and epidermal TJs. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  14. The tight junction protein Z O-2 has several functional nuclear export signals

    International Nuclear Information System (INIS)

    Gonzalez-Mariscal, Lorenza; Ponce, Arturo; Alarcon, Lourdes; Jaramillo, Blanca Estela

    2006-01-01

    The tight junction (TJ) protein ZO-2 changes its subcellular distribution according to the state of confluency of the culture. Thus in confluent monolayers, it localizes at the TJ region whereas in sparse cultures it concentrates at the nucleus. The canine sequence of ZO-2 displays four putative nuclear export signals (NES), two at the second PDZ domain (NES-0 and NES-1) and the rest at the GK region (NES-2 and NES-3). The functionality of NES-0 and NES-3 was unknown, hence here we have explored it with a nuclear export assay, injecting into the nucleus of MDCK cells peptides corresponding to the ZO-2 NES sequences chemically coupled to ovalbumin. We show that both NES-0 and NES-3 are functional and sensitive to leptomycin B. We also demonstrate that NES-1, previously characterized as a non functional NES, is rendered capable of nuclear export upon the acquisition of a negative charge at its Ser369 residue. Experiments performed injecting at the nucleus WT and mutated ZO-2-GST fusion proteins revealed the need of both NES-0 and NES-1, and NES-2 and NES-3 for attaining an efficient nuclear exit of the respective amino and middle segments of ZO-2. Moreover, the transfection of MDCK cells with full-length ZO-2 revealed that the mutation of any of the NES present in the molecule was sufficient to induce nuclear accumulation of the protein

  15. Electron transport in a bilayer graphene/layered superconductor NbSe2 junction: effect of work function difference

    Science.gov (United States)

    Yarimizu, Katsuhide; Tomori, Hikari; Watanabe, Kenji; Taniguchi, Takashi; Kanda, Akinobu

    2018-03-01

    We have experimentally studied electron transport in a bilayer graphene (BLG)/layered superconductor NbSe2 junction encapsulated with hexagonal boron nitride. The junction exhibits nonlinear current-voltage characteristics which strongly depend on the gate voltage around the charge neutrality point (CNP) of the BLG. Besides, we observe that the gate voltage dependence of electron transport in the BLG portion close to the junction interface is different from that of the BLG portion apart from the interface, indicating that the spatial variation of the Dirac point in the charge transfer region due to the difference in work function between superconductor and graphene needs to be considered in the analysis of the superconducting proximity effect.

  16. Functional lateralization of temporoparietal junction - imitation inhibition, visual perspective-taking and theory of mind.

    Science.gov (United States)

    Santiesteban, Idalmis; Banissy, Michael J; Catmur, Caroline; Bird, Geoffrey

    2015-10-01

    Although neuroimaging studies have consistently identified the temporoparietal junction (TPJ) as a key brain region involved in social cognition, the literature is far from consistent with respect to lateralization of function. For example, during theory-of-mind tasks bilateral TPJ activation is found in some studies but only right hemisphere activation in others. Visual perspective-taking and imitation inhibition, which have been argued to recruit the same socio-cognitive processes as theory of mind, are associated with unilateral activation of either left TPJ (perspective taking) or right TPJ (imitation inhibition). The present study investigated the functional lateralization of TPJ involvement in the above three socio-cognitive abilities using transcranial direct current stimulation. Three groups of healthy adults received anodal stimulation over right TPJ, left TPJ or the occipital cortex prior to performing three tasks (imitation inhibition, visual perspective-taking and theory of mind). In contrast to the extant neuroimaging literature, our results suggest bilateral TPJ involvement in imitation inhibition and visual perspective-taking, while no effect of anodal stimulation was observed on theory of mind. The discrepancy between these findings and those obtained using neuroimaging highlight the efficacy of neurostimulation as a complementary methodological tool in cognitive neuroscience. © 2015 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

  17. Survival Function Analysis of Planet Size Distribution

    OpenAIRE

    Zeng, Li; Jacobsen, Stein B.; Sasselov, Dimitar D.; Vanderburg, Andrew

    2018-01-01

    Applying the survival function analysis to the planet radius distribution of the Kepler exoplanet candidates, we have identified two natural divisions of planet radius at 4 Earth radii and 10 Earth radii. These divisions place constraints on planet formation and interior structure model. The division at 4 Earth radii separates small exoplanets from large exoplanets above. When combined with the recently-discovered radius gap at 2 Earth radii, it supports the treatment of planets 2-4 Earth rad...

  18. Tight junction protein ZO-2 expression and relative function of ZO-1 and ZO-2 during mouse blastocyst formation

    International Nuclear Information System (INIS)

    Sheth, Bhavwanti; Nowak, Rachael L.; Anderson, Rebecca; Kwong, Wing Yee; Papenbrock, Thomas; Fleming, Tom P.

    2008-01-01

    Apicolateral tight junctions (TJs) between epithelial cells are multiprotein complexes regulating membrane polarity and paracellular transport and also contribute to signalling pathways affecting cell proliferation and gene expression. ZO-2 and other ZO family members form a sub-membranous scaffold for binding TJ constituents. We investigated ZO-2 contribution to TJ biogenesis and function during trophectoderm epithelium differentiation in mouse preimplantation embryos. Our data indicate that ZO-2 is expressed from maternal and embryonic genomes with maternal ZO-2 protein associated with nuclei in zygotes and particularly early cleavage stages. Embryonic ZO-2 assembled at outer blastomere apicolateral junctional sites from the late 16-cell stage. Junctional ZO-2 first co-localised with E-cadherin in a transient complex comprising adherens junction and TJ constituents before segregating to TJs after their separation from the blastocyst stage (32-cell onwards). ZO-2 siRNA microinjection into zygotes or 2-cell embryos resulted in specific knockdown of ZO-2 mRNA and protein within blastocysts. Embryos lacking ZO-2 protein at trophectoderm TJs exhibited delayed blastocoel cavity formation but underwent normal cell proliferation and outgrowth morphogenesis. Quantitative analysis of trophectoderm TJs in ZO-2-deficient embryos revealed increased assembly of ZO-1 but not occludin, indicating ZO protein redundancy as a compensatory mechanism contributing to the mild phenotype observed. In contrast, ZO-1 knockdown, or combined ZO-1 and ZO-2 knockdown, generated a more severe inhibition of blastocoel formation indicating distinct roles for ZO proteins in blastocyst morphogenesis

  19. Quantum conductance of 4,4-bipyridine molecular junctions: Role of electrode work function and local d band

    DEFF Research Database (Denmark)

    Rauba, J.M.C.; Strange, Mikkel; Thygesen, Kristian Sommer

    2008-01-01

    conductance than the Pt-BPD junction due to the smaller work function of Au as compared to Pt. On the other hand, coupling to the local d band is stronger in the case of Pt and this broadens the LUMO resonance. We find that these effects largely outbalance each other leading to conductances of 0.01G(0) and 0......-principles results within a simple single-level model....

  20. Generation of functional neuromuscular junctions from human pluripotent stem cell lines

    Directory of Open Access Journals (Sweden)

    Katja ePuttonen

    2015-12-01

    Full Text Available Several neuromuscular diseases involve dysfunction of neuromuscular junctions (NMJs, yet there are no patient-specific human models for electrophysiological characterization of NMJ. We seeded cells of neurally-induced embryoid body-like spheres derived from induced pluripotent stem cell (iPSC or embryonic stem cell (ESC lines as monolayers without basic fibroblast factor (bFGF and observed differentiation of neuronal as well as spontaneously contracting, multinucleated skeletal myotubes. The myotubes showed striation, immunoreactivity for myosin heavy chain, actin bundles typical for myo-oriented cells, and generated spontaneous and evoked action potentials (APs. The myogenic differentiation was associated with expression of MyoD1, myogenin and type I ryanodine receptor. Neurons formed end plate like structures with strong binding of α-bungarotoxin, a marker of nicotinic acetylcholine receptors highly expressed in the postsynaptic membrane of NMJs, and expressed SMI-32, a motoneuron marker, as well as SV2, a marker for synapses. Pharmacological stimulation of cholinergic receptors resulted in strong depolarization of myotube membrane and raised Ca2+ concentration in sarcoplasm, while electrical stimulation evoked Ca2+ transients in myotubes. Stimulation of motoneurons with N-Methyl-D-aspartate resulted in reproducible APs in myotubes and end plates displayed typical MEPs and tonic activity depolarizing myotubes of about 10 mV. We conclude that simultaneous differentiation of neurons and myotubes from patient-specific iPSCs or ESCs results also in the development of functional NMJs. Our human model of NMJ may serve as an important tool to investigate normal development, mechanisms of diseases and novel drug targets involving NMJ dysfunction and degeneration.

  1. Renal pyramid echogenicity in ureteropelvic junction obstruction: correlation between altered echogenicity and differential renal function

    Energy Technology Data Exchange (ETDEWEB)

    Chavhan, Govind; Daneman, Alan; Lim, Ruth; Traubici, Jeffrey [University of Toronto, Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto (Canada); Moineddin, Rahim [University of Toronto, Department of Family and Community Medicine, Toronto (Canada); Langlois, Valerie [University of Toronto, Division of Nephrology, Department of Pediatrics, Hospital for Sick Children, Toronto (Canada)

    2008-10-15

    Improvement in resolution and use of high-frequency transducers in US has enabled visualization of previously unreported changes in medullary pyramid echogenicity in children with obstructive hydronephrosis. To determine whether these unreported changes in echogenicity and morphology of the renal pyramids in ureteropelvic junction (UPJ) obstruction correlate with differential renal function (DRF) of the kidney as determined by technetium-99m mercaptoacetyltriglycine ({sup 99m}Tc-MAG3) scan. Renal sonograms in 60 children with UPJ obstruction were retrospectively reviewed. Children were divided into three groups based on the echogenicity of the pyramids: (1) normal echogenicity of the pyramids, (2) increased echogenicity of the pyramids with maintained corticomedullary differentiation (CMD), and (3) loss of CMD. DRF, as determined by {sup 99m}Tc-MAG3 scan, of the obstructed kidney of {>=}45% was considered normal and of {<=}44% was considered abnormal based on a published study correlating histological changes with DRF. Fisher's exact test was performed for assessing the association between DRF and altered echogenicity of the pyramids. In group 1, which consisted of 13 patients with normal pyramids on US, DRF was normal in 11 and abnormal in two. In group 2, which consisted of 33 patients with echogenic pyramids and preserved CMD, DRF was normal in 15 and abnormal in 18. In group 3, which consisted of 14 patients with complete loss of CMD, DRF was normal in 2 and abnormal in 12. There was a strong correlation between abnormal pyramids and DRF (P=0.0009). The risk ratio (RR) of DRF becoming abnormal for those kidneys with abnormal echogenicity of the pyramids with preserved CMD (group 2) compared to normal pyramid echogenicity (group 1) was 1.56 (95% CI 1.088-2.236). The RR of DRF becoming abnormal for those kidneys with loss of CMD (group 3) compared to normal pyramid echogenicity (group 1) was 5.571 (95% CI 1.530-20.294). We observed that in obstructed kidneys

  2. Improved split renal function after percutaneous nephrostomy in young adults with severe hydronephrosis due to ureteropelvic junction obstruction.

    Science.gov (United States)

    Zhang, Shiwei; Zhang, Qing; Ji, Changwei; Zhao, Xiaozhi; Liu, Guangxiang; Zhang, Shun; Li, Xiaogong; Lian, Huibo; Zhang, Gutian; Guo, Hongqian

    2015-01-01

    We evaluated percutaneous nephrostomy for adult kidneys with severe hydronephrosis due to ureteropelvic junction obstruction and less than 10% split renal function. In this retrospective analysis we included patients who underwent percutaneous nephrostomy for unilateral ureteropelvic junction obstruction of the kidneys with hydronephrosis and less than 10% split renal function at our hospital between May 2009 and January 2012. Adults (age 18 years or greater) were divided into those 35 years or younger (young adults) and older than 35 years (older adults). The percutaneous nephrostomy remained in situ a mean ± SD of 6.62 ± 2.55 weeks and patients underwent repeat renography before pyeloplasty. When there was no significant improvement in split renal function (10% or greater) and drainage (greater than 400 ml per day), nephrectomy was performed. Otherwise pyeloplasty was performed. Patients were followed by renography, ultrasound and contrast computerized tomography at 3 and 6 months, at 1 year and annually thereafter. Of 53 patients 30 (56.6%) showed improvement after percutaneous nephrostomy drainage and urine output greater than 400 ml per day with percutaneous nephrostomy. Pyeloplasty was then performed. Of 29 young adults 24 (82.8%) showed improved split renal function vs 6 of 24 older adults (25%). Nephrectomy of the other 23 kidneys was performed. At a mean followup of 19.27 ± 7.82 months (range 12 to 36), no patient showed hypertension or urinary tract infection. Split renal function detected by renography may not accurately predict recovered, poorly functioning kidneys, especially in young adults. First observing the recoverability of hydronephrotic kidneys by percutaneous nephrostomy drainage and then preserving select kidneys may be an effective method to manage poorly functioning kidneys due to ureteropelvic junction obstruction. Copyright © 2015 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights

  3. Oligomeric structure and functional characterization of Caenorhabditis elegans Innexin-6 gap junction protein.

    Science.gov (United States)

    Oshima, Atsunori; Matsuzawa, Tomohiro; Nishikawa, Kouki; Fujiyoshi, Yoshinori

    2013-04-12

    Innexin is the molecular component of invertebrate gap junctions. Here we successfully expressed and purified Caenorhabditis elegans innexin-6 (INX-6) gap junction channels and characterized the molecular dimensions and channel permeability using electron microscopy (EM) and microinjection of fluorescent dye tracers, respectively. Negative staining and thin-section EM of isolated INX-6 gap junction membranes revealed a loosely packed hexagonal lattice and a greater cross-sectional width than that of connexin26 and connexin43 (Cx43)-GFP. In gel filtration analysis, the elution profile of purified INX-6 channels in dodecyl maltoside solution exhibited a peak at ∼400 kDa that was shifted to ∼800 kDa in octyl glucose neopentyl glycol. We also obtained the class averages of purified INX-6 channels from these peak fractions by single particle analysis. The class average from the ∼800-kDa fraction showed features of the junction form with a longitudinal height of 220 Å, a channel diameter of 110 Å in the absence of detergent micelles, and an extracellular gap space of 60 Å, whereas the class averages from the ∼400-kDa fraction showed diameters of up to 140 Å in the presence of detergent micelles. These findings indicate that the purified INX-6 channels are predominantly hemichannels in dodecyl maltoside and docked junction channels in octyl glucose neopentyl glycol. Dye transfer experiments revealed that the INX-6-GFP-His channels are permeable to 3- and 10-kDa tracers, whereas no significant amounts of these tracers passed through the Cx43-GFP channels. Based on these findings, INX-6 channels have a larger overall structure and greater permeability than connexin channels.

  4. Oligomeric Structure and Functional Characterization of Caenorhabditis elegans Innexin-6 Gap Junction Protein*

    Science.gov (United States)

    Oshima, Atsunori; Matsuzawa, Tomohiro; Nishikawa, Kouki; Fujiyoshi, Yoshinori

    2013-01-01

    Innexin is the molecular component of invertebrate gap junctions. Here we successfully expressed and purified Caenorhabditis elegans innexin-6 (INX-6) gap junction channels and characterized the molecular dimensions and channel permeability using electron microscopy (EM) and microinjection of fluorescent dye tracers, respectively. Negative staining and thin-section EM of isolated INX-6 gap junction membranes revealed a loosely packed hexagonal lattice and a greater cross-sectional width than that of connexin26 and connexin43 (Cx43)-GFP. In gel filtration analysis, the elution profile of purified INX-6 channels in dodecyl maltoside solution exhibited a peak at ∼400 kDa that was shifted to ∼800 kDa in octyl glucose neopentyl glycol. We also obtained the class averages of purified INX-6 channels from these peak fractions by single particle analysis. The class average from the ∼800-kDa fraction showed features of the junction form with a longitudinal height of 220 Å, a channel diameter of 110 Å in the absence of detergent micelles, and an extracellular gap space of 60 Å, whereas the class averages from the ∼400-kDa fraction showed diameters of up to 140 Å in the presence of detergent micelles. These findings indicate that the purified INX-6 channels are predominantly hemichannels in dodecyl maltoside and docked junction channels in octyl glucose neopentyl glycol. Dye transfer experiments revealed that the INX-6-GFP-His channels are permeable to 3- and 10-kDa tracers, whereas no significant amounts of these tracers passed through the Cx43-GFP channels. Based on these findings, INX-6 channels have a larger overall structure and greater permeability than connexin channels. PMID:23460640

  5. Functional Size Measurement applied to UML-based user requirements

    NARCIS (Netherlands)

    van den Berg, Klaas; Dekkers, Ton; Oudshoorn, Rogier; Dekkers, T.

    There is a growing interest in applying standardized methods for Functional Size Measurement (FSM) to Functional User Requirements (FUR) based on models in the Unified Modelling Language (UML). No consensus exists on this issue. We analyzed the demands that FSM places on FURs. We propose a

  6. Measuring Neuromuscular Junction Functionality in the SOD1(G93A) Animal Model of Amyotrophic Lateral Sclerosis.

    Science.gov (United States)

    Rizzuto, Emanuele; Pisu, Simona; Musarò, Antonio; Del Prete, Zaccaria

    2015-09-01

    Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that leads to motor neuron degeneration, alteration in neuromuscular junctions (NMJs), muscle atrophy, and paralysis. To investigate the NMJ functionality in ALS we tested, in vitro, two innervated muscle types excised from SOD1(G93A) transgenic mice at the end-stage of the disease: the Soleus, a postural muscle almost completely paralyzed at that stage, and the diaphragm, which, on the contrary, is functional until death. To this aim we employed an experimental protocol that combined two types of electrical stimulation: the direct stimulation and the stimulation through the nerve. The technique we applied allowed us to determine the relevance of NMJ functionality separately from muscle contractile properties in SOD1(G93A) animal model. Functional measurements revealed that the muscle contractility of transgenic diaphragms is almost unaltered in comparison to control muscles, while transgenic Soleus muscles were severely compromised. In contrast, when stimulated via the nerve, both transgenic muscle types showed a strong decrease of the contraction force, a slowing down of the kinetic parameters, as well as alterations in the neurotransmission failure parameter. All together, these results confirm a severely impaired functionality in the SOD1(G93A) neuromuscular junctions.

  7. The enhanced spin-polarized transport behaviors through cobalt benzene-porphyrin-benzene molecular junctions: the effect of functional groups

    Science.gov (United States)

    Cheng, Jue-Fei; Zhou, Liping; Wen, Zhongqian; Yan, Qiang; Han, Qin; Gao, Lei

    2017-05-01

    The modification effects of the groups amino (NH2) and nitro (NO2) on the spin polarized transport properties of the cobalt benzene-porphyrin-benzene (Co-BPB) molecule coupled to gold (Au) nanowire electrodes are investigated by the nonequilibrium Green’s function method combined with the density functional theory. The calculation results show that functional groups can lead to the significant spin-filter effect, enhanced low-bias negative differential resistance (NDR) behavior and novel reverse rectifying effect in Co-BPB molecular junction. The locations and types of functional groups have distinct influences on spin-polarized transport performances. The configuration with NH2 group substituting H atom in central porphyrin ring has larger spin-down current compared to that with NO2 substitution. And Co-BPB molecule junction with NH2 group substituting H atom in side benzene ring shows reverse rectifying effect. Detailed analyses confirm that NH2 and NO2 group substitution change the spin-polarized transferred charge, which makes the highest occupied molecular orbitals (HOMO) of spin-down channel of Co-BPB closer to the Fermi level. And the shift of HOMO strengthens the spin-polarized coupling between the molecular orbitals and the electrodes, leading to the enhanced spin-polarized behavior. Our findings might be useful in the design of multi-functional molecular devices in the future.

  8. Supramolecular tunneling junctions

    NARCIS (Netherlands)

    Wimbush, K.S.

    2012-01-01

    In this study a variety of supramolecular tunneling junctions were created. The basis of these junctions was a self-assembled monolayer of heptathioether functionalized ß-cyclodextrin (ßCD) formed on an ultra-flat Au surface, i.e., the bottom electrode. This gave a well-defined hexagonally packed

  9. [The characteristics of esophagogastric junction contractile index in patients with gastroesophageal reflux disease or functional heartburn].

    Science.gov (United States)

    Wang, K; Duan, L P; Ge, Y; Xia, Z W; Xu, Z J

    2016-04-01

    To study the role of esophagogastric junction contractile index (EGJ-CI) in evaluating the function of anti-reflux barrier, and in differentiating patients with gastroesophageal reflux disease (GERD) from those with functional heartburn (FH). A total of 115 patients presenting heartburn were enrolled in the study from January 2012 to June 2015.All subjects had completed Gerd-Q questionnaire and undergone gastroscopy, 24-hour pH-impedance monitoring and esophageal high-resolution manometry. GERD patients were divided into as reflux esophagitis, acid-nonerosive reflux disease (NERD) and weakly acid-NERD groups. Patients with normal esophageal mucosa, normal acid exposure and negative proton pump inhibitor test were enrolled in FH group. EGJ-CI (mmHg·cm) as well as EGJ rest pressure and 4s integrated relaxation pressure (IRP 4s) were measured. Among the 115 patients, 18 were reflux esophagitis [(49.0±18.9) years, M∶F=10∶8], 25 were acid-NERD [(48.7±14.4) years, M∶F=13∶12], 37 were weakly acid-NERD [(52.0±14.8) years, M∶F=15∶22] and 35 were FH [(53.6±14.8), M∶F=8∶27]. No differences of Gerd-Q scores were noticed between the four groups. (1)Negative correlations were demonstrated between EGJ-CI and esophageal acid exposure time (r=-0.283, P=0.002), EGJ-CI and acid reflux events (r=-0.233, P=0.012), EGJ-CI and weakly acid reflux events (r=-0.213, P=0.022), EGJ-CI and non-acid reflux events (r=-0.200, P=0.032). (2)The value of EGJ-CI was significantly higher in FH patients than in the three subgroups of GERD(all P<0.01). EGJ rest pressure of FH group was higher than that of acid-NERD (P<0.01). IRP 4s in acid-NERD group was lower than that of FH and weakly acid-NERD (P<0.05). (3)The area under curve (AUC) of EGJ-CI was higher than that of EGJ-CIT, EGJ rest pressure or IRP 4s(0.686 vs 0.678, 0.641 and 0.578). The cut-off value of EGJ-CI to differentiate GERD from FH was 9.74 mmHg·cm with sensitivity 82.86% and specificity 51.52%. The EGJ-CI values are

  10. Effects of adenine nucleotide and sterol depletion on tight junction structure and function in MDCK cells

    International Nuclear Information System (INIS)

    Ladino, C.A.

    1988-01-01

    The antitumor agent Hadacidin (H), N-formyl-hydroxyamino-acetic acid, reversibly inhibited the multiplication of clone 4 Madin-Darby canine kidney (MDCK) cells at a 4 mM concentration within 24-48 hours. Treated cells were arrested in the S phase of the cell cycle. Accompanying this action was a 16-fold increase in the area occupied b the cells and a refractoriness to trypsin treatment. To test whether this effect was due to an increase in tight junction integrity, electrical resistance (TER) was measured across H-treated monolayers. Addition of H at the onset of junction formation reversibly prevented the development of TER. ATP and cAMP levels were decreased by H, as well as the rate of [ 3 H]-leucine incorporation into protein. When 1 mM dibutyryl-cAMP (d.cAMP) and theophylline were added, H had no effect on cell division or protein synthesis, and TER was partially restored. The addition of 1 mM d.cAMP and 1 mM theophylline to control cultures decreased TER, indicating a biphasic effect on TER development/maintenance. In a separate study, the effect of sterol depletion on tight junctions formation/maintenance in wild-type MDCK cells was investigated

  11. Experimental Phase Functions of Millimeter-sized Cosmic Dust Grains

    Energy Technology Data Exchange (ETDEWEB)

    Muñoz, O.; Moreno, F.; Guirado, D.; Escobar-Cerezo, J. [Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía s/n, E-18008 Granada (Spain); Vargas-Martín, F. [Department of Electromagnetism and Electronics, University of Murcia, E-30100 Murcia (Spain); Min, M. [SRON Netherlands Institute for Space Research, Sobornnelaan 2, 3584 CA Utrecht (Netherlands); Hovenier, J. W. [Astronomical Institute “Anton Pannekoek,” University of Amsterdam, Science Park 904, 1098 XH, Amsterdam (Netherlands)

    2017-09-01

    We present the experimental phase functions of three types of millimeter-sized dust grains consisting of enstatite, quartz, and volcanic material from Mount Etna, respectively. The three grains present similar sizes but different absorbing properties. The measurements are performed at 527 nm covering the scattering angle range from 3° to 170°. The measured phase functions show two well-defined regions: (i) soft forward peaks and (ii) a continuous increase with the scattering angle at side- and back-scattering regions. This behavior at side- and back-scattering regions is in agreement with the observed phase functions of the Fomalhaut and HR 4796A dust rings. Further computations and measurements (including polarization) for millimeter-sized grains are needed to draw some conclusions about the fluffy or compact structure of the dust grains.

  12. Impact of Base Functional Component Types on Software Functional Size based Effort Estimation

    OpenAIRE

    Gencel, Cigdem; Buglione, Luigi

    2008-01-01

    Software effort estimation is still a significant challenge for software management. Although Functional Size Measurement (FSM) methods have been standardized and have become widely used by the software organizations, the relationship between functional size and development effort still needs further investigation. Most of the studies focus on the project cost drivers and consider total software functional size as the primary input to estimation models. In this study, we investigate whether u...

  13. Symmetric and Asymmetric Magnetic Tunnel Junctions with Embedded Nanoparticles: Effects of Size Distribution and Temperature on Tunneling Magnetoresistance and Spin Transfer Torque.

    Science.gov (United States)

    Useinov, Arthur; Lin, Hsiu-Hau; Lai, Chih-Huang

    2017-08-21

    The problem of the ballistic electron tunneling is considered in magnetic tunnel junction with embedded non-magnetic nanoparticles (NP-MTJ), which creates additional conducting middle layer. The strong temperature impact was found in the system with averaged NP diameter d av  tunneling magnetoresistance (TMR) voltage behaviors. The low temperature approach also predicts step-like TMR and quantized in-plane spin transfer torque (STT) effects. The robust asymmetric STT respond is found due to voltage sign inversion in NP-MTJs with barrier asymmetry. Furthermore, it is shown how size distribution of NPs as well as quantization rules modify the spin-current filtering properties of the nanoparticles in ballistic regime. Different quantization rules for the transverse component of the wave vector are considered to overpass the dimensional threshold (d av  ≈ 1.8 nm) between quantum well and bulk-assisted states of the middle layer.

  14. Dissection of the functional domains of an archaeal holliday junction helicase

    DEFF Research Database (Denmark)

    Hong, Ye; Chu, Mingzhu; Li, Yansheng

    2012-01-01

    Helicases and nucleases form complexes that play very important roles in DNA repair pathways some of which interact with each other at Holliday junctions. In this study, we present in vitro and in vivo analysis of Hjm and its interaction with Hjc in Sulfolobus. In vitro studies employed Hjm from...... conformation change of the enzyme. Furthermore, StoHjm is able to prevent the formation of Hjc/HJ high complex, suggesting a regulation mechanism of Hjm to the activity of Hjc. We show that Hjm is essential for cell viability using recently developed genetic system and mutant propagation assay, suggesting...

  15. Platelet size and age determine platelet function independently

    International Nuclear Information System (INIS)

    Thompson, C.B.; Jakubowski, J.A.; Quinn, P.G.; Deykin, D.; Valeri, C.R.

    1984-01-01

    A study was undertaken to examine the interaction of platelet size and age in determining in vitro platelet function. Baboon megakaryocytes were labeled in vivo by the injection of 75Se-methionine. Blood was collected when the label was predominantly associated with younger platelets (day 2) and with older platelets (day 9). Size-dependent platelet subpopulations were prepared on both days by counterflow centrifugation. The reactivity of each platelet subpopulation was determined on both days by measuring thrombin-induced aggregation. Platelets were fixed after partial aggregation had occurred by the addition of EDTA/formalin. After removal of the aggregated platelets by differential centrifugation, the supernatant medium was assayed for remaining platelets and 75Se radioactivity. Comparing day 2 and day 9, no significant difference was seen in the rate of aggregation of a given subpopulation. However, aggregation was more rapid in the larger platelet fractions than in the smaller ones on both days. A greater percentage of the 75Se radioactivity appeared in the platelet aggregates on day 2 than on day 9. This effect was independent of platelet size, as it occurred to a similar extent in the unfractionated platelets and in each of the size-dependent platelet subpopulations. The data indicate that young platelets are more active than older platelets. This study demonstrates that size and age are both determinants of platelet function, but by independent mechanisms

  16. Structural and Functional Changes in the Tight Junctions of Asymptomatic and Serology-negative First-degree Relatives of Patients With Celiac Disease.

    Science.gov (United States)

    Mishra, Asha; Prakash, Shyam; Sreenivas, Vishnubhatla; Das, Taposh K; Ahuja, Vineet; Gupta, Siddhartha D; Makharia, Govind K

    2016-08-01

    Ten to 15% of first-degree relatives (FDRs) of celiac disease (CeD) patients develop CeD. Although intestinal barrier functions (intestinal permeability) are abnormal in the subset of serology-negative FDRs, what leads to the abnormal barrier function is not known. To study the ultrastructure and functions of tight junctions in serology-negative FDRs of CeD patients. The intestinal permeability was measured in 97 asymptomatic and anti-tissue transglutaminase antibody (anti-tTG Ab)-negative FDRs (using the lactulose mannitol ratio) and in 75 controls. The ultrastructure of tight junctions using transmission electron microscopy, and the expression of key tight junction proteins (claudin-2, claudin-3, occludin, JAM-A, and ZO-1) and zonulin using real-time PCR and immunohistochemistry were assessed in anti-tTG Ab-negative, HLA-DQ2/-DQ8-positive FDRs having normal villi and in disease controls. In addition, the serum zonulin level was measured in 172 anti-tTG Ab-negative FDRs and 198 controls. The intestinal permeability was significantly increased in FDRs than in controls. Ultrastructural abnormalities such as dilatation of the tight junction (P=0.004) and loss of the pentalaminar structure (P=0.001) were more common in FDRs than in disease controls. There was significant underexpression of tight junction proteins ZO-1 (P=0.040) and occludin (P=0.041) in FDRs. There was no significant difference in the serum zonulin level between FDRs and controls (P=0.154). Even asymptomatic, anti-tTG-Ab-negative FDRs with a normal villous histology have both ultrastructural and functional abnormalities in tight junctions. These findings are indirect evidence of the presence of tight junction abnormalities before the onset of the disease and may have therapeutic implications.

  17. "V-junction": a novel structure for high-speed generation of bespoke droplet flows.

    Science.gov (United States)

    Ding, Yun; Casadevall i Solvas, Xavier; deMello, Andrew

    2015-01-21

    We present the use of microfluidic "V-junctions" as a droplet generation strategy that incorporates enhanced performance characteristics when compared to more traditional "T-junction" formats. This includes the ability to generate target-sized droplets from the very first one, efficient switching between multiple input samples, the production of a wide range of droplet sizes (and size gradients) and the facile generation of droplets with residence time gradients. Additionally, the use of V-junction droplet generators enables the suspension and subsequent resumption of droplet flows at times defined by the user. The high degree of operational flexibility allows a wide range of droplet sizes, payloads, spacings and generation frequencies to be obtained, which in turn provides for an enhanced design space for droplet-based experimentation. We show that the V-junction retains the simplicity of operation associated with T-junction formats, whilst offering functionalities normally associated with droplet-on-demand technologies.

  18. Tight junctions and human diseases.

    Science.gov (United States)

    Sawada, Norimasa; Murata, Masaki; Kikuchi, Keisuke; Osanai, Makoto; Tobioka, Hirotoshi; Kojima, Takashi; Chiba, Hideki

    2003-09-01

    Tight junctions are intercellular junctions adjacent to the apical end of the lateral membrane surface. They have two functions, the barrier (or gate) function and the fence function. The barrier function of tight junctions regulates the passage of ions, water, and various macromolecules, even of cancer cells, through paracellular spaces. The barrier function is thus relevant to edema, jaundice, diarrhea, and blood-borne metastasis. On the other hand, the fence function maintains cell polarity. In other words, tight junctions work as a fence to prevent intermixing of molecules in the apical membrane with those in the lateral membrane. This function is deeply involved in cancer cell biology, in terms of loss of cell polarity. Of the proteins comprising tight junctions, integral membrane proteins occludin, claudins, and JAMs have been recently discovered. Of these molecules, claudins are exclusively responsible for the formation of tight-junction strands and are connected with the actin cytoskeleton mediated by ZO-1. Thus, both functions of tight junctions are dependent on the integrity of the actin cytoskeleton as well as ATP. Mutations in the claudin14 and the claudin16 genes result in hereditary deafness and hereditary hypomagnesemia, respectively. Some pathogenic bacteria and viruses target and affect the tight-junction function, leading to diseases. In this review, the relationship between tight junctions and human diseases is summarized.

  19. Adenosine Receptors in Developing and Adult Mouse Neuromuscular Junctions and Functional Links With Other Metabotropic Receptor Pathways.

    Science.gov (United States)

    Tomàs, Josep; Garcia, Neus; Lanuza, Maria A; Santafé, Manel M; Tomàs, Marta; Nadal, Laura; Hurtado, Erica; Simó-Ollé, Anna; Cilleros-Mañé, Víctor; Just-Borràs, Laia

    2018-01-01

    In the last few years, we have studied the presence and involvement in synaptogenesis and mature transmitter release of the adenosine autoreceptors (AR) in the mammalian neuromuscular junction (NMJ). Here, we review and bring together the previously published data to emphasize the relevance of these receptors for developmental axonal competition, synaptic loss and mature NMJ functional modulation. However, in addition to AR, activity-dependent mediators originating from any of the three cells that make the synapse (nerve, muscle, and glial cells) cross the extracellular cleft to generate signals in target metabotropic receptors. Thus, the integrated interpretation of the complementary function of all these receptors is needed. We previously studied, in the NMJ, the links of AR with mAChR and the neurotrophin receptor TrkB in the control of synapse elimination and transmitter release. We conclude that AR cooperate with these receptors through synergistic and antagonistic effects in the developmental synapse elimination process. In the adult NMJ, this cooperation is manifested so as that the functional integrity of a given receptor group depends on the other receptors operating normally (i.e., the functional integrity of mAChR depends on AR operating normally). These observations underlie the relevance of AR in the NMJ function.

  20. Adenosine Receptors in Developing and Adult Mouse Neuromuscular Junctions and Functional Links With Other Metabotropic Receptor Pathways

    Directory of Open Access Journals (Sweden)

    Josep Tomàs

    2018-04-01

    Full Text Available In the last few years, we have studied the presence and involvement in synaptogenesis and mature transmitter release of the adenosine autoreceptors (AR in the mammalian neuromuscular junction (NMJ. Here, we review and bring together the previously published data to emphasize the relevance of these receptors for developmental axonal competition, synaptic loss and mature NMJ functional modulation. However, in addition to AR, activity-dependent mediators originating from any of the three cells that make the synapse (nerve, muscle, and glial cells cross the extracellular cleft to generate signals in target metabotropic receptors. Thus, the integrated interpretation of the complementary function of all these receptors is needed. We previously studied, in the NMJ, the links of AR with mAChR and the neurotrophin receptor TrkB in the control of synapse elimination and transmitter release. We conclude that AR cooperate with these receptors through synergistic and antagonistic effects in the developmental synapse elimination process. In the adult NMJ, this cooperation is manifested so as that the functional integrity of a given receptor group depends on the other receptors operating normally (i.e., the functional integrity of mAChR depends on AR operating normally. These observations underlie the relevance of AR in the NMJ function.

  1. Nuclear export of RNA: Different sizes, shapes and functions.

    Science.gov (United States)

    Williams, Tobias; Ngo, Linh H; Wickramasinghe, Vihandha O

    2018-03-01

    Export of protein-coding and non-coding RNA molecules from the nucleus to the cytoplasm is critical for gene expression. This necessitates the continuous transport of RNA species of different size, shape and function through nuclear pore complexes via export receptors and adaptor proteins. Here, we provide an overview of the major RNA export pathways in humans, highlighting the similarities and differences between each. Its importance is underscored by the growing appreciation that deregulation of RNA export pathways is associated with human diseases like cancer. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

  2. Structural and functional insights into the malaria parasite moving junction complex.

    Directory of Open Access Journals (Sweden)

    Brigitte Vulliez-Le Normand

    Full Text Available Members of the phylum Apicomplexa, which include the malaria parasite Plasmodium, share many features in their invasion mechanism in spite of their diverse host cell specificities and life cycle characteristics. The formation of a moving junction (MJ between the membranes of the invading apicomplexan parasite and the host cell is common to these intracellular pathogens. The MJ contains two key parasite components: the surface protein Apical Membrane Antigen 1 (AMA1 and its receptor, the Rhoptry Neck Protein (RON complex, which is targeted to the host cell membrane during invasion. In particular, RON2, a transmembrane component of the RON complex, interacts directly with AMA1. Here, we report the crystal structure of AMA1 from Plasmodium falciparum in complex with a peptide derived from the extracellular region of PfRON2, highlighting clear specificities of the P. falciparum RON2-AMA1 interaction. The receptor-binding site of PfAMA1 comprises the hydrophobic groove and a region that becomes exposed by displacement of the flexible Domain II loop. Mutations of key contact residues of PfRON2 and PfAMA1 abrogate binding between the recombinant proteins. Although PfRON2 contacts some polymorphic residues, binding studies with PfAMA1 from different strains show that these have little effect on affinity. Moreover, we demonstrate that the PfRON2 peptide inhibits erythrocyte invasion by P. falciparum merozoites and that this strong inhibitory potency is not affected by AMA1 polymorphisms. In parallel, we have determined the crystal structure of PfAMA1 in complex with the invasion-inhibitory peptide R1 derived by phage display, revealing an unexpected structural mimicry of the PfRON2 peptide. These results identify the key residues governing the interactions between AMA1 and RON2 in P. falciparum and suggest novel approaches to antimalarial therapeutics.

  3. Finite-size effects on current correlation functions

    Science.gov (United States)

    Chen, Shunda; Zhang, Yong; Wang, Jiao; Zhao, Hong

    2014-02-01

    We study why the calculation of current correlation functions (CCFs) still suffers from finite-size effects even when the periodic boundary condition is taken. Two important one-dimensional, momentum-conserving systems are investigated as examples. Intriguingly, it is found that the state of a system recurs in the sense of microcanonical ensemble average, and such recurrence may result in oscillations in CCFs. Meanwhile, we find that the sound mode collisions induce an extra time decay in a current so that its correlation function decays faster (slower) in a smaller (larger) system. Based on these two unveiled mechanisms, a procedure for correctly evaluating the decay rate of a CCF is proposed, with which our analysis suggests that the global energy CCF decays as ˜t-2/3 in the diatomic hard-core gas model and in a manner close to ˜t-1/2 in the Fermi-Pasta-Ulam-β model.

  4. Quantum Junction Solar Cells

    KAUST Repository

    Tang, Jiang

    2012-09-12

    Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO 2); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics. © 2012 American Chemical Society.

  5. Quasiparticle Green's function theory of the Josephson effect in chiral p-wave superconductor/diffusive normal metal/chiral p-wave superconductor junctions

    NARCIS (Netherlands)

    Sawa, Y.; Yokoyama, T.; Tanaka, Y.; Golubov, Alexandre Avraamovitch

    2007-01-01

    We study the Josephson effect in chiral p-wave superconductor/diffusive normal metal (DN)/chiral p-wave superconductor (CP/DN/CP) junctions using quasiclassical Green's function formalism with proper boundary conditions. The px+ipy-wave symmetry of superconducting order parameter is chosen which is

  6. Ontogenetic functional diversity: size structure of a keystone predator drives functioning of a complex ecosystem.

    Science.gov (United States)

    Rudolf, Volker H W; Rasmussen, Nick L

    2013-05-01

    A central challenge in community ecology is to understand the connection between biodiversity and the functioning of ecosystems. While traditional approaches have largely focused on species-level diversity, increasing evidence indicates that there exists substantial ecological diversity among individuals within species. By far, the largest source of this intraspecific diversity stems from variation among individuals in ontogenetic stage and size. Although such ontogenetic shifts are ubiquitous in natural communities, whether and how they scale up to influence the structure and functioning of complex ecosystems is largely unknown. Here we take an experimental approach to examine the consequences of ontogenetic niche shifts for the structure of communities and ecosystem processes. In particular we experimentally manipulated the stage structure in a keystone predator, larvae of the dragonfly Anax junius, in complex experimental pond communities to test whether changes in the population stage or size structure of a keystone species scale up to alter community structure and ecosystem processes, and how functional differences scale with relative differences in size among stages. We found that the functional role of A. junius was stage-specific. Altering what stages were present in a pond led to concurrent changes in community structure, primary producer biomass (periphyton and phytoplankton), and ultimately altered ecosystem processes (respiration and net primary productivity), indicating a strong, but stage-specific, trophic cascade. Interestingly, the stage-specific effects did not simply scale with size or biomass of the predator, but instead indicated clear ontogenetic niche shifts in ecological interactions. Thus, functional differences among stages within a keystone species scaled up to alter the functioning of entire ecosystems. Therefore, our results indicate that the classical approach of assuming an average functional role of a species can be misleading because

  7. Density functional theory study on Herzberg-Teller contribution in Raman scattering from 4-aminothiophenol-metal complex and metal-4-aminothiophenol-metal junction

    Science.gov (United States)

    Liu, Shasha; Zhao, Xiuming; Li, Yuanzuo; Zhao, Xiaohong; Chen, Maodu

    2009-06-01

    Density functional theory (DFT) and time-dependent DFT calculations have been performed to investigate the Raman scattering spectra of metal-molecule complex and metal-molecule-metal junction architectures interconnected with 4-aminothiophenol (PATP) molecule. The simulated profiles of normal Raman scattering (NRS) spectra for the two complexes (Ag2-PATP and PATP-Au2) and the two junctions (Ag2-PATP-Au2 and Au2-PATP-Ag2) are similar to each other, but exhibit obviously different Raman intensities. Due to the lager static polarizabilities of the two junctions, which directly influence the ground state chemical enhancement in NRS spectra, the calculated normal Raman intensities of them are stronger than those of two complexes by the factor of 102. We calculate preresonance Raman scattering (RRS) spectra with incident light at 1064 nm, which is much lower than the S1 electronic transition energy of complexes and junctions. Ag2-PATP-Au2 and Au2-PATP-Ag2 junctions yield higher Raman intensities than those of Ag2-PATP and PATP-Au2 complexes, especially for b2 modes. This effect is mainly attributed to charge transfer (CT) between the metal gap and the PAPT molecule which results in the occurrence of CT resonance enhancement. The calculated pre-RRS spectra strongly depend on the electronic transition state produced by new structures. With excitation at 514.5 nm, the calculated pre-RRS spectra of two complexes and two junctions are stronger than those of with excitation at 1064 nm. A charge difference densities methodology has been used to visually describe chemical enhancement mechanism of RRS spectrum. This methodology aims at visualizing intermolecular CT which provides direct evidence of the Herzberg-Teller mechanism.

  8. Functional size analysis of bioactive materials by radiation inactivation

    International Nuclear Information System (INIS)

    Kume, Tamikazu

    1994-01-01

    When the research on various proteins including enzymes is carried out, first molecular weight is measured. The physical chemical methods used for measuring molecular weight cannot measure it in the state of actually acting in living bodies. Radiation inactivation method is the unique method which can measure the molecular weight of the active substances in living bodies. Paying attention to this point, recently it is attempted to measure the activity unit of enzymes, receptors and others, and to apply to the elucidation of their functions. In this report, the concept of the method of measuring molecular size based on radiation inactivation, the detailed experimental method and the points to which attention must be paid are described. Also its application to the elucidation of living body functions according to the example of the studies by the author is reported. The concept of the measurement of molecular weight by radiation inactivation is based on target theory. The preparation of samples, the effect of oxygen, radiation sources, dosimetry, irradiation temperature, internal standard process and so on are reported. The trend of the research is shown. (K.I.)

  9. Analysis of trafficking, stability and function of human connexin 26 gap junction channels with deafness-causing mutations in the fourth transmembrane helix.

    Directory of Open Access Journals (Sweden)

    Cinzia Ambrosi

    Full Text Available Human Connexin26 gene mutations cause hearing loss. These hereditary mutations are the leading cause of childhood deafness worldwide. Mutations in gap junction proteins (connexins can impair intercellular communication by eliminating protein synthesis, mis-trafficking, or inducing channels that fail to dock or have aberrant function. We previously identified a new class of mutants that form non-functional gap junction channels and hemichannels (connexons by disrupting packing and inter-helix interactions. Here we analyzed fourteen point mutations in the fourth transmembrane helix of connexin26 (Cx26 that cause non-syndromic hearing loss. Eight mutations caused mis-trafficking (K188R, F191L, V198M, S199F, G200R, I203K, L205P, T208P. Of the remaining six that formed gap junctions in mammalian cells, M195T and A197S formed stable hemichannels after isolation with a baculovirus/Sf9 protein purification system, while C202F, I203T, L205V and N206S formed hemichannels with varying degrees of instability. The function of all six gap junction-forming mutants was further assessed through measurement of dye coupling in mammalian cells and junctional conductance in paired Xenopus oocytes. Dye coupling between cell pairs was reduced by varying degrees for all six mutants. In homotypic oocyte pairings, only A197S induced measurable conductance. In heterotypic pairings with wild-type Cx26, five of the six mutants formed functional gap junction channels, albeit with reduced efficiency. None of the mutants displayed significant alterations in sensitivity to transjunctional voltage or induced conductive hemichannels in single oocytes. Intra-hemichannel interactions between mutant and wild-type proteins were assessed in rescue experiments using baculovirus expression in Sf9 insect cells. Of the four unstable mutations (C202F, I203T, L205V, N206S only C202F and N206S formed stable hemichannels when co-expressed with wild-type Cx26. Stable M195T hemichannels

  10. Heterocellular interaction enhances recruitment of α and β-catenins and ZO-2 into functional gap-junction complexes and induces gap junction-dependant differentiation of mammary epithelial cells

    International Nuclear Information System (INIS)

    Talhouk, Rabih S.; Mroue, Rana; Mokalled, Mayssa; Abi-Mosleh, Lina; Nehme, Ralda; Ismail, Ayman; Khalil, Antoine; Zaatari, Mira; El-Sabban, Marwan E.

    2008-01-01

    Gap junctions (GJ) are required for mammary epithelial differentiation. Using epithelial (SCp2) and myoepithelial-like (SCg6) mouse-derived mammary cells, the role of heterocellular interaction in assembly of GJ complexes and functional differentiation (β-casein expression) was evaluated. Heterocellular interaction is critical for β-casein expression, independent of exogenous basement membrane or cell anchoring substrata. Functional differentiation of SCp2, co-cultured with SCg6, is more sensitive to GJ inhibition relative to homocellular SCp2 cultures differentiated by exogenous basement membrane. Connexin (Cx)32 and Cx43 levels were not regulated across culture conditions; however, GJ functionality was enhanced under differentiation-permissive conditions. Immunoprecipitation studies demonstrated association of junctional complex components (α-catenin, β-catenin and ZO-2) with Cx32 and Cx43, in differentiation conditions, and additionally with Cx30 in heterocellular cultures. Although β-catenin did not shuttle between cadherin and GJ complexes, increased association between connexins and β-catenin in heterocellular cultures was observed. This was concomitant with reduced nuclear β-catenin, suggesting that differentiation in heterocellular cultures involves sequestration of β-catenin in GJ complexes

  11. Advance of Mechanically Controllable Break Junction for Molecular Electronics.

    Science.gov (United States)

    Wang, Lu; Wang, Ling; Zhang, Lei; Xiang, Dong

    2017-06-01

    Molecular electronics stands for the ultimate size of functional elements, keeping up with an unstoppable trend over the past few decades. As a vital component of molecular electronics, single molecular junctions have attracted significant attention from research groups all over the world. Due to its pronounced superiority, the mechanically controllable break junctions (MCBJ) technique has been widely applied to characterize the dynamic performance of single molecular junctions. This review presents a system analysis for single-molecule junctions and offers an overview of four test-beds for single-molecule junctions, thus offering more insight into the mechanisms of electron transport. We mainly focus on the development of state-of-the-art mechanically controlled break junctions. The three-terminal gated MCBJ approaches are introduced to manipulate the electron transport of molecules, and MCBJs are combined with characterization techniques. Additionally, applications of MCBJs and remarkable properties of single molecules are addressed. Finally, the challenges and perspective for the mechanically controllable break junctions technique are provided.

  12. Structure and Function of a Novel ATPase that Interacts with Holliday Junction Resolvase Hjc and Promotes Branch Migration.

    Science.gov (United States)

    Zhai, Binyuan; DuPrez, Kevin; Doukov, Tzanko I; Li, Huan; Huang, Mengting; Shang, Guijun; Ni, Jinfeng; Gu, Lichuan; Shen, Yulong; Fan, Li

    2017-04-07

    Holliday junction (HJ) is a hallmark intermediate in DNA recombination and must be processed by dissolution (for double HJ) or resolution to ensure genome stability. Although HJ resolvases have been identified in all domains of life, there is a long-standing effort to search in prokaryotes and eukarya for proteins promoting HJ migration. Here, we report the structural and functional characterization of a novel ATPase, Sulfolobus islandicusPilT N-terminal-domain-containing ATPase (SisPINA), encoded by the gene adjacent to the resolvase Hjc coding gene. PINA is conserved in archaea and vital for S. islandicus viability. Purified SisPINA forms hexameric rings in the crystalline state and in solution, similar to the HJ migration helicase RuvB in Gram-negative bacteria. Structural analysis suggests that ATP binding and hydrolysis cause conformational changes in SisPINA to drive branch migration. Further studies reveal that SisPINA interacts with SisHjc and coordinates HJ migration and cleavage. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Identification of Human Junctional Adhesion Molecule 1 as a Functional Receptor for the Hom-1 Calicivirus on Human Cells

    Directory of Open Access Journals (Sweden)

    Stanislav V. Sosnovtsev

    2017-02-01

    Full Text Available The Hom-1 vesivirus was reported in 1998 following the inadvertent transmission of the animal calicivirus San Miguel sea lion virus to a human host in a laboratory. We characterized the Hom-1 strain and investigated the mechanism by which human cells could be infected. An expression library of 3,559 human plasma membrane proteins was screened for reactivity with Hom-1 virus-like particles, and a single interacting protein, human junctional adhesion molecule 1 (hJAM1, was identified. Transient expression of hJAM1 conferred susceptibility to Hom-1 infection on nonpermissive Chinese hamster ovary (CHO cells. Virus infection was markedly inhibited when CHO cells stably expressing hJAM were pretreated with anti-hJAM1 monoclonal antibodies. Cell lines of human origin were tested for growth of Hom-1, and efficient replication was observed in HepG2, HuH7, and SK-CO15 cells. The three cell lines (of hepatic or intestinal origin were confirmed to express hJAM1 on their surface, and clustered regularly interspaced short palindromic repeats/Cas9-mediated knockout of the hJAM1 gene in each line abolished Hom-1 propagation. Taken together, our data indicate that entry of the Hom-1 vesivirus into these permissive human cell lines is mediated by the plasma membrane protein hJAM1 as a functional receptor.

  14. Functional neuromuscular junctions formed by embryonic stem cell-derived motor neurons.

    Directory of Open Access Journals (Sweden)

    Joy A Umbach

    Full Text Available A key objective of stem cell biology is to create physiologically relevant cells suitable for modeling disease pathologies in vitro. Much progress towards this goal has been made in the area of motor neuron (MN disease through the development of methods to direct spinal MN formation from both embryonic and induced pluripotent stem cells. Previous studies have characterized these neurons with respect to their molecular and intrinsic functional properties. However, the synaptic activity of stem cell-derived MNs remains less well defined. In this study, we report the development of low-density co-culture conditions that encourage the formation of active neuromuscular synapses between stem cell-derived MNs and muscle cells in vitro. Fluorescence microscopy reveals the expression of numerous synaptic proteins at these contacts, while dual patch clamp recording detects both spontaneous and multi-quantal evoked synaptic responses similar to those observed in vivo. Together, these findings demonstrate that stem cell-derived MNs innervate muscle cells in a functionally relevant manner. This dual recording approach further offers a sensitive and quantitative assay platform to probe disorders of synaptic dysfunction associated with MN disease.

  15. Thermal transport through a spin-phonon interacting junction: A nonequilibrium Green's function method study

    Science.gov (United States)

    Zhang, Zu-Quan; Lü, Jing-Tao

    2017-09-01

    Using the nonequilibrium Green's function method, we consider heat transport in an insulating ferromagnetic spin chain model with spin-phonon interaction under an external magnetic field. Employing the Holstein-Primakoff transformation to the spin system, we treat the resulted magnon-phonon interaction within the self-consistent Born approximation. We find the magnon-phonon coupling can change qualitatively the magnon thermal conductance in the high-temperature regime. At a spectral mismatched ferromagnetic-normal insulator interface, we also find thermal rectification and negative differential thermal conductance due to the magnon-phonon interaction. We show that these effects can be effectively tuned by the external applied magnetic field, a convenient advantage absent in anharmonic phonon and electron-phonon systems studied before.

  16. GEN1 from a thermophilic fungus is functionally closely similar to non-eukaryotic junction-resolving enzymes.

    Science.gov (United States)

    Freeman, Alasdair D J; Liu, Yijin; Déclais, Anne-Cécile; Gartner, Anton; Lilley, David M J

    2014-12-12

    Processing of Holliday junctions is essential in recombination. We have identified the gene for the junction-resolving enzyme GEN1 from the thermophilic fungus Chaetomium thermophilum and expressed the N-terminal 487-amino-acid section. The protein is a nuclease that is highly selective for four-way DNA junctions, cleaving 1nt 3' to the point of strand exchange on two strands symmetrically disposed about a diagonal axis. CtGEN1 binds to DNA junctions as a discrete homodimer with nanomolar affinity. Analysis of the kinetics of cruciform cleavage shows that cleavage of the second strand occurs an order of magnitude faster than the first cleavage so as to generate a productive resolution event. All these properties are closely similar to those described for bacterial, phage and mitochondrial junction-resolving enzymes. CtGEN1 is also similar in properties to the human enzyme but lacks the problems with aggregation that currently prevent detailed analysis of the latter protein. CtGEN1 is thus an excellent enzyme with which to engage in biophysical and structural analysis of eukaryotic GEN1. Copyright © 2014. Published by Elsevier Ltd.

  17. An Effect Size Measure for Raju's Differential Functioning for Items and Tests

    Science.gov (United States)

    Wright, Keith D.; Oshima, T. C.

    2015-01-01

    This study established an effect size measure for differential functioning for items and tests' noncompensatory differential item functioning (NCDIF). The Mantel-Haenszel parameter served as the benchmark for developing NCDIF's effect size measure for reporting moderate and large differential item functioning in test items. The effect size of…

  18. Method of manufacturing Josephson junction integrated circuits

    International Nuclear Information System (INIS)

    Jillie, D.W. Jr.; Smith, L.N.

    1985-01-01

    Josephson junction integrated circuits of the current injection type and magnetically controlled type utilize a superconductive layer that forms both Josephson junction electrode for the Josephson junction devices on the integrated circuit as well as a ground plane for the integrated circuit. Large area Josephson junctions are utilized for effecting contact to lower superconductive layers and islands are formed in superconductive layers to provide isolation between the groudplane function and the Josephson junction electrode function as well as to effect crossovers. A superconductor-barrier-superconductor trilayer patterned by local anodization is also utilized with additional layers formed thereover. Methods of manufacturing the embodiments of the invention are disclosed

  19. Nonequilibrium green function approach to elastic and inelastic spin-charge transport in topological insulator-based heterostructures and magnetic tunnel junctions

    Science.gov (United States)

    Mahfouzi, Farzad

    Current and future technological needs increasingly motivate the intensive scientific research of the properties of materials at the nano-scale. One of the most important domains in this respect at present concerns nano-electronics and its diverse applications. The great interest in this domain arises from the potential reduction of the size of the circuit components, maintaining their quality and functionality, and aiming at greater efficiency, economy, and storage characteristics for the corresponding physical devices. The aim of this thesis is to present a contribution to the analysis of the electronic charge and spin transport phenomena that occur at the quantum level in nano-structures. This thesis spans the areas of quantum transport theory through time-dependent systems, electron-boson interacting systems and systems of interest to spintronics. A common thread in the thesis is to develop the theoretical foundations and computational algorithms to numerically simulate such systems. In order to optimize the numerical calculations I resort to different techniques (such as graph theory in finding inverse of a sparse matrix, adaptive grids for integrations and programming languages (e.g., MATLAB and C++) and distributed computing tools (MPI, CUDA). Outline of the Thesis: After giving an introduction to the topics covered in this thesis in Chapter 1, I present the theoretical foundations to the field of non-equilibrium quantum statistics in Chapter 2. The applications of this formalism and the results are covered in the subsequent chapters as follows: Spin and charge quantum pumping in time-dependent systems: Covered in Chapters 3, 4 and 5, this topics was initially motivated by experiments on measuring voltage signal from a magnetic tunnel junction (MTJ) exposed to a microwave radiation in ferromagnetic resonance (FMR) condition. In Chapter 3 we found a possible explanation for the finite voltage signal measured from a tunnel junction consisting of only a single

  20. Work function and temperature dependence of electron tunneling through an N-type perylene diimide molecular junction with isocyanide surface linkers.

    Science.gov (United States)

    Smith, Christopher E; Xie, Zuoti; Bâldea, Ioan; Frisbie, C Daniel

    2018-01-18

    Conducting probe atomic force microscopy (CP-AFM) was employed to examine electron tunneling in self-assembled monolayer (SAM) junctions. A 2.3 nm long perylene tetracarboxylic acid diimide (PDI) acceptor molecule equipped with isocyanide linker groups was synthesized, adsorbed onto Ag, Au and Pt substrates, and the current-voltage (I-V) properties were measured by CP-AFM. The dependence of the low-bias resistance (R) on contact work function indicates that transport is LUMO-assisted ('n-type behavior'). A single-level tunneling model combined with transition voltage spectroscopy (TVS) was employed to analyze the experimental I-V curves and to extract the effective LUMO position ε l = E LUMO - E F and the effective electronic coupling (Γ) between the PDI redox core and the contacts. This analysis revealed a strong Fermi level (E F ) pinning effect in all the junctions, likely due to interface dipoles that significantly increased with increasing contact work function, as revealed by scanning Kelvin probe microscopy (SKPM). Furthermore, the temperature (T) dependence of R was found to be substantial. For Pt/Pt junctions, R varied more than two orders of magnitude in the range 248 K tunneling mechanism and allow independent determination of ε l , giving values compatible with estimates of ε l based on analysis of the full I-V data. Theoretical analysis revealed a general criterion to unambiguously rule out a two-step transport mechanism: namely, if measured resistance data exhibit a pronounced Arrhenius-type temperature dependence, a two-step electron transfer scenario should be excluded in cases where the activation energy depends on contact metallurgy. Overall, our results indicate (1) the generality of the Fermi level pinning phenomenon in molecular junctions, (2) the utility of employing the single level tunneling model for determining essential electronic structure parameters (ε l and Γ), and (3) the importance of changing the nature of the contacts to

  1. Radon emanation rate as a function of monazite grain size

    International Nuclear Information System (INIS)

    Yogesan, S.; Stanley, J.D.; Rosli Mahat; Yusof Md Amin

    1995-01-01

    In this study, a sample of monazite from local mining area was divided to 7 parts according to size (μm) and each sample was analysed using silicon surface barrier detector and multichannel analyser. From this study it has found that small grain monazite produced more radon that big grain monazite and radium is distributed on or near the surface of the monazite grain

  2. The oligodendroglial precursor cell line Oli-neu represents a cell culture system to examine functional expression of the mouse gap junction gene connexin29 (Cx29

    Directory of Open Access Journals (Sweden)

    Goran Christoph Söhl

    2013-06-01

    Full Text Available The potential gap junction forming mouse connexin29 (Cx29 protein is concomitantly expressed with connexin32 (Cx32 in peripheral myelin forming Schwann cells and together with both Cx32 and connexin47 (Cx47 in oligodendrocytes of the CNS. To study the genomic structure and functional expression of Cx29, either primary cells or cell culture systems might be selected, from which the latter are easier to cultivate. Both structure and expression of Cx29 is still not fully understood. In the mouse sciatic nerve, brain and the oligodendroglial precursor cell line Oli-neu the Cx29 gene is processed in two transcript isoforms both harbouring a unique reading frame. In contrast to Cx32 and Cx47, only Cx29 protein is abundantly expressed in undifferentiated as well as differentiated Oli-neu cells but the absence of Etbr dye transfer after microinjection concealed the function of Cx29 mediated gap junction communication between those cells. Although HeLa cells stably transfected with Cx29 or Cx29-eGFP neither demonstrated any permeability for Lucifer yellow nor for neurobiotin, blocking of Etbr uptake from the media by gap junction blockers does suppose a role of Cx29 in hemi-channel function. Thus, we conclude that, due to its high abundance of Cx29 expression and its reproducible culture conditions, the oligodendroglial precursor cell line Oli-neu might constitute an appropriate cell culture system to study molecular mechanisms or putative extracellular stimuli to functionally open Cx29 channels or hemi-channels.

  3. Qualitative assessment of anorectal junction levels and anorectal angles to investigate functional differences between constipation and fecal incontinence

    International Nuclear Information System (INIS)

    Shannon, S.I.; Somers, S.; Anvari, M.; Stevenson, G.W.; Waterfall, W.E.; Huizinga, J.D.

    1989-01-01

    Female patients consecutively referred for defecography, with either chronic constipation or incontinence, were assessed for posterior anorectal angle and anorectal junction level as measured from the ischial tuberosities. The clinical groups did not differ in grades of rectoceles, enteroceles, or intussusception. Both constipated and incontinent patients had a low resting anorectal junction position compared with that of volunteers, indicating a stretched pelvic floor. Despite this, the constipated patients achieved a similar degree of lift of the pelvic floor on squeezing as controls, and they also showed significant angle changes on lifting and straining. Incontinent patients showed a significantly smaller amount of lift than controls, a significantly larger descent than constipated patients, and no angle changes on lifting and straining. These data are consistent with significantly weaker pelvic floor muscles in incontinent compared with constipated patients, despite a similar degree of stretching

  4. Density functional approach for pairing in finite size systems

    International Nuclear Information System (INIS)

    Hupin, G.

    2011-09-01

    The combination of functional theory where the energy is written as a functional of the density, and the configuration mixing method, provides an efficient description of nuclear ground and excited state properties. The specific pathologies that have been recently observed, show the lack of a clear underlying justification associated to the breaking and the restoration of symmetries within density functional theory. This thesis focuses on alternative treatments of pairing correlations in finite many body systems that consider the breaking and the restoration of the particle number conservation. The energy is written as a functional of a projected quasi-particle vacuum and can be linked to the one obtained within the configuration mixing framework. This approach has been applied to make the projection either before or after the application of the variational principle. It is more flexible than the usual configuration mixing method since it can handle more general effective interactions than the latter. The application to the Krypton isotopes shows the feasibility and the efficiency of the method to describe pairing near closed shell nuclei. Following a parallel path, a theory where the energy is written as a functional of the occupation number and natural orbitals is proposed. The new functional is benchmarked in an exactly solvable model, the pairing Hamiltonian. The efficiency and the applicability of the new theory have been tested for various pairing strengths, single particle energy spectra and numbers of particles. (author)

  5. Star junctions and watermelons of pure or random quantum Ising chains: finite-size properties of the energy gap at criticality

    Science.gov (United States)

    Monthus, Cécile

    2015-06-01

    We consider M  ⩾  2 pure or random quantum Ising chains of N spins when they are coupled via a single star junction at their origins or when they are coupled via two star junctions at the their two ends leading to the watermelon geometry. The energy gap is studied via a sequential self-dual real-space renormalization procedure that can be explicitly solved in terms of Kesten variables containing the initial couplings and and the initial transverse fields. In the pure case at criticality, the gap is found to decay as a power-law {ΔM}\\propto {{N}-z(M)} with the dynamical exponent z(M)=\\frac{M}{2} for the single star junction (the case M   =   2 corresponds to z   =   1 for a single chain with free boundary conditions) and z(M)   =   M  -  1 for the watermelon (the case M   =   2 corresponds to z   =   1 for a single chain with periodic boundary conditions). In the random case at criticality, the gap follows the Infinite Disorder Fixed Point scaling \\ln {ΔM}=-{{N}\\psi}g with the same activated exponent \\psi =\\frac{1}{2} as the single chain corresponding to M   =   2, and where g is an O(1) random positive variable, whose distribution depends upon the number M of chains and upon the geometry (star or watermelon).

  6. Model of a tunneling current in a p-n junction based on armchair graphene nanoribbons - an Airy function approach and a transfer matrix method

    International Nuclear Information System (INIS)

    Suhendi, Endi; Syariati, Rifki; Noor, Fatimah A.; Khairurrijal; Kurniasih, Neny

    2014-01-01

    We modeled a tunneling current in a p-n junction based on armchair graphene nanoribbons (AGNRs) by using an Airy function approach (AFA) and a transfer matrix method (TMM). We used β-type AGNRs, in which its band gap energy and electron effective mass depends on its width as given by the extended Huckel theory. It was shown that the tunneling currents evaluated by employing the AFA are the same as those obtained under the TMM. Moreover, the calculated tunneling current was proportional to the voltage bias and inversely with temperature

  7. Estimating Functions of Distributions Defined over Spaces of Unknown Size

    Directory of Open Access Journals (Sweden)

    David H. Wolpert

    2013-10-01

    Full Text Available We consider Bayesian estimation of information-theoretic quantities from data, using a Dirichlet prior. Acknowledging the uncertainty of the event space size m and the Dirichlet prior’s concentration parameter c, we treat both as random variables set by a hyperprior. We show that the associated hyperprior, P(c, m, obeys a simple “Irrelevance of Unseen Variables” (IUV desideratum iff P(c, m = P(cP(m. Thus, requiring IUV greatly reduces the number of degrees of freedom of the hyperprior. Some information-theoretic quantities can be expressed multiple ways, in terms of different event spaces, e.g., mutual information. With all hyperpriors (implicitly used in earlier work, different choices of this event space lead to different posterior expected values of these information-theoretic quantities. We show that there is no such dependence on the choice of event space for a hyperprior that obeys IUV. We also derive a result that allows us to exploit IUV to greatly simplify calculations, like the posterior expected mutual information or posterior expected multi-information. We also use computer experiments to favorably compare an IUV-based estimator of entropy to three alternative methods in common use. We end by discussing how seemingly innocuous changes to the formalization of an estimation problem can substantially affect the resultant estimates of posterior expectations.

  8. Development of an Innovative Intradermal siRNA Delivery System Using a Combination of a Functional Stearylated Cytoplasm-Responsive Peptide and a Tight Junction-Opening Peptide

    Directory of Open Access Journals (Sweden)

    Hisako Ibaraki

    2016-09-01

    Full Text Available As a new category of therapeutics for skin diseases including atopic dermatitis (AD, nucleic acids are gaining importance in the clinical setting. Intradermal administration is noninvasive and improves patients′ quality of life. However, intradermal small interfering RNA (siRNA delivery is difficult because of two barriers encountered in the skin: intercellular lipids in the stratum corneum and tight junctions in the stratum granulosum. Tight junctions are the major barrier in AD; therefore, we focused on functional peptides to devise an intradermal siRNA delivery system for topical skin application. In this study, we examined intradermal siRNA permeability in the tape-stripped (20 times back skin of mice or AD-like skin of auricles treated with 6-carboxyfluorescein-aminohexyl phosphoramidite (FAM-labeled siRNA, the tight junction modulator AT1002, and the functional cytoplasm-responsive stearylated peptide STR-CH2R4H2C by using confocal laser microscopy. We found that strong fluorescence was observed deep and wide in the epidermis and dermis of back skin and AD-like ears after siRNA with STR-CH2R4H2C and AT1002 treatment. After 10 h from administration, brightness of FAM-siRNA was significantly higher for STR-CH2R4H2C + AT1002, compared to other groups. In addition, we confirmed the nontoxicity of STR-CH2R4H2C as a siRNA carrier using PAM212 cells. Thus, our results demonstrate the applicability of the combination of STR-CH2R4H2C and AT1002 for effective intradermal siRNA delivery.

  9. Flexible 2D layered material junctions

    Science.gov (United States)

    Balabai, R.; Solomenko, A.

    2018-03-01

    Within the framework of the methods of the electron density functional and the ab initio pseudopotential, we have obtained the valence electron density spatial distribution, the densities of electron states, the widths of band gaps, the charges on combined regions, and the Coulomb potentials for graphene-based flexible 2D layered junctions, using author program complex. It is determined that the bending of the 2D layered junctions on the angle α leads to changes in the electronic properties of these junctions. In the graphene/graphane junction, there is clear charge redistribution with different signs in the regions of junctions. The presence in the heterojunctions of charge regions with different signs leads to the formation of potential barriers. The greatest potential jump is in the graphene/fluorographene junction. The greatest value of the band gap width is in the graphene/graphane junction.

  10. Polydisperse-particle-size-distribution function determined from intensity profile of angularly scattered light

    International Nuclear Information System (INIS)

    Alger, T.W.

    1979-01-01

    A new method for determining the particle-size-distribution function of a polydispersion of spherical particles is presented. The inversion technique for the particle-size-distribution function is based upon matching the measured intensity profile of angularly scattered light with a summation of the intensity contributions of a series of appropriately spaced, narrowband, size-distribution functions. A numerical optimization technique is used to determine the strengths of the individual bands that yield the best agreement with the measured scattered-light-intensity profile. Because Mie theory is used, the method is applicable to spherical particles of all sizes. Several numerical examples demonstrate the application of this inversion method

  11. Influence of size-corrected bound-electron contribution on nanometric silver dielectric function. Sizing through optical extinction spectroscopy

    International Nuclear Information System (INIS)

    Santillán, J M J; Videla, F A; Scaffardi, L B; Schinca, D C; Fernández van Raap, M B; Muraca, D

    2013-01-01

    The study of metal nanoparticles (NPs) is of great interest due to their ability to enhance optical fields on the nanometric scale, which makes them interesting for various applications in several fields of science and technology. In particular, their optical properties depend on the dielectric function of the metal, its size, shape and surrounding environment. This work analyses the contributions of free and bound electrons to the complex dielectric function of spherical silver NPs and their influence on the optical extinction spectra. The contribution of free electrons is usually corrected for particle size under 10 nm, introducing a modification of the damping constant to account for the extra collisions with the particle's boundary. For the contribution of bound electrons, we considered the interband transitions from the d-band to the conduction band including the size dependence of the electronic density states for radii below 2 nm. Bearing in mind these specific modifications, it was possible to determine optical and band energy parameters by fitting the bulk complex dielectric function. The results obtained from the optimum fit are: K bulk = 2 × 10 24 (coefficient for bound-electron contribution), E g = 1.91 eV (gap energy), E F = 4.12 eV (Fermi energy), and γ b = 1.5 × 10 14 Hz (damping constant for bound electrons). Based on this size-dependent dielectric function, extinction spectra of silver particles in the nanometric–subnanometric radius range can be calculated using Mie's theory, and its size behaviour analysed. These studies are applied to fit experimental extinction spectrum of very small spherical particles fabricated by fs laser ablation of a solid target in water. From the fitting, the structure and size distribution of core radius and shell thickness of the colloidal suspension could be determined. The spectroscopic results suggest that the colloidal suspension is composed by two types of structures: bare core and core–shell. The former

  12. Poly(2-vinyl pyridine)-block-poly(ethylene oxide) featuring a furan group at the block junction-synthesis and functionalization.

    Science.gov (United States)

    Rudolph, Tobias; Barthel, Markus J; Kretschmer, Florian; Mansfeld, Ulrich; Hoeppener, Stephanie; Hager, Martin D; Schubert, Ulrich S; Schacher, Felix H

    2014-05-01

    Furfuryl glycidyl ether (FGE) represents a highly versatile monomer for the preparation of reversibly cross-linkable nanostructured materials via Diels-Alder reactions. Here, the use of FGE for the mid-chain functionalization of a P2VP-b-PEO diblock copolymer is reported. The material features one furan moiety at the block junction, P2VP68 -FGE-b-PEO390 , which can be subsequently addressed in Diels-Alder reactions using maleimide-functionalized counterparts. The presence of the FGE moiety enables the introduction of dyes as model labels or the formation of hetero-grafted brushes as shell on hybrid Au@Polymer nanoparticles. This renders P2VP68 -FGE-b-PEO390 , a powerful tool for selective functionalization reactions, including the modification of surfaces. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Value of 'functional' magnetic resonance imaging in the diagnosis of ligamentous affection at the craniovertebral junction

    Energy Technology Data Exchange (ETDEWEB)

    Lummel, Nina, E-mail: nina.lummel@med.uni-muenchen.de [Department of Neuroradiology, University of Munich (LMU), Marchioninistrasse 15, D - 81377 Munich (Germany); Bitterling, Harro, E-mail: Harro.Bitterling@shs.regionsyddanmark.dk [Billeddiagnostisk Afdeling SBS/TS, Sygehus Sonderjylland, Sydvang 1, DK - 6400 Sonderborg (Denmark); Kloetzer, Andrea, E-mail: andreakloetzer@yahoo.de [Department of Neuroradiology, University of Munich (LMU), Marchioninistrasse 15, D - 81377 Munich (Germany); Zeif, Christian, E-mail: zeif@ilo.de [Department of Neuroradiology, University of Munich (LMU), Marchioninistrasse 15, D - 81377 Munich (Germany); Brueckmann, Hartmut, E-mail: hartmut.brueckmann@med.uni-muenchen.de [Department of Neuroradiology, University of Munich (LMU), Marchioninistrasse 15, D - 81377 Munich (Germany); Linn, Jennifer, E-mail: jennifer.linn@med.uni-muenchen.de [Department of Neuroradiology, University of Munich (LMU), Marchioninistrasse 15, D - 81377 Munich (Germany)

    2012-11-15

    Introduction: Objective of this investigation was to evaluate the rotational mobility at the craniocervical junction and changes in the width of the subarachnoid space during head rotation in healthy volunteers using Magnetic Resonance Imaging (MRI). Materials and Methods: In 30 healthy volunteers axial 3 mm Half-Fourier Acquisition Single-Shot Turbo Spin-Echo (HASTE) sequences were obtained with the subject's head in neutral position, and in maximal rotation to the left and right respectively. All MRI examinations were evaluated by two neuroradiologists in consensus. The ranges of axial rotation at C0-C2 as well as the width of the subarachnoid space in neutral, and in maximal rotated position were measured. Student's t-tests were used to compare group differences. Results: Total range of right-to-left-rotation at C0-C2 was 59-183 Degree-Sign with mean rotation to the right and left side of 70 Degree-Sign ({+-}12.7 Degree-Sign ) and 75 Degree-Sign ({+-}13.0 Degree-Sign ). Difference between degrees of rotation to both sides was on average 4.9 Degree-Sign ({+-}7.1 Degree-Sign ) with a significantly greater rotational range to the left compared to the right. In neutral position, distance between the dura and the ventral wall of the cervical spinal cord was 1.6-4.2 mm. In active rotation interface between dura and myelon was evident in 19 volunteers with unilateral contact in 7, and bilateral contact in 12 cases. Conclusions: High variablity of rotational mobility at the craniocervical junction and attenuation of width of the subarachnoid space during head rotation are frequent findings in an asymptomatic population. Our results indicate that the assessment of these parameters is of limited diagnostic value in patients with whiplash-associated disorders.

  14. Early-stage evolution of particle size distribution with Johnson's SB function due to Brownian coagulation

    International Nuclear Information System (INIS)

    Tang Hong; Lin Jianzhong

    2013-01-01

    The moment method can be used to determine the time evolution of particle size distribution due to Brownian coagulation based on the general dynamic equation (GDE). But the function form of the initial particle size distribution must be determined beforehand for the moment method. If the assumed function type of the initial particle size distribution has an obvious deviation from the true particle population, the evolution of particle size distribution may be different from the real evolution tendency. Thus, a simple and general method is proposed based on the moment method. In this method, the Johnson's S B function is chosen as a general distribution function to fit the initial distributions including the log normal (L-N), Rosin–Rammler (R-R), normal (N-N) and gamma distribution functions, respectively. Meanwhile, using the modified beta function to fit the L-N, R-R, N-N and gamma functions is also conducted as a comparison in order to present the advantage of the Johnson's S B function as the general distribution function. And then, the time evolution of particle size distributions using the Johnson's S B function as the initial distribution can be obtained by several lower order moment equations of the Johnson's S B function in conjunction with the GDE during the Brownian coagulation process. Simulation experiments indicate that fairly reasonable results of the time evolution of particle size distribution can be obtained with this proposed method in the free molecule regime, transition regime and continuum plus near continuum regime, respectively, at the early time stage of evolution. The Johnson's S B function has the ability of describing the early time evolution of different initial particle size distributions. (paper)

  15. Peltier cooling in molecular junctions

    Science.gov (United States)

    Cui, Longji; Miao, Ruijiao; Wang, Kun; Thompson, Dakotah; Zotti, Linda Angela; Cuevas, Juan Carlos; Meyhofer, Edgar; Reddy, Pramod

    2018-02-01

    The study of thermoelectricity in molecular junctions is of fundamental interest for the development of various technologies including cooling (refrigeration) and heat-to-electricity conversion1-4. Recent experimental progress in probing the thermopower (Seebeck effect) of molecular junctions5-9 has enabled studies of the relationship between thermoelectricity and molecular structure10,11. However, observations of Peltier cooling in molecular junctions—a critical step for establishing molecular-based refrigeration—have remained inaccessible. Here, we report direct experimental observations of Peltier cooling in molecular junctions. By integrating conducting-probe atomic force microscopy12,13 with custom-fabricated picowatt-resolution calorimetric microdevices, we created an experimental platform that enables the unified characterization of electrical, thermoelectric and energy dissipation characteristics of molecular junctions. Using this platform, we studied gold junctions with prototypical molecules (Au-biphenyl-4,4'-dithiol-Au, Au-terphenyl-4,4''-dithiol-Au and Au-4,4'-bipyridine-Au) and revealed the relationship between heating or cooling and charge transmission characteristics. Our experimental conclusions are supported by self-energy-corrected density functional theory calculations. We expect these advances to stimulate studies of both thermal and thermoelectric transport in molecular junctions where the possibility of extraordinarily efficient energy conversion has been theoretically predicted2-4,14.

  16. The non-linear relationship between body size and function in parrotfishes

    Science.gov (United States)

    Lokrantz, J.; Nyström, M.; Thyresson, M.; Johansson, C.

    2008-12-01

    Parrotfishes are a group of herbivores that play an important functional role in structuring benthic communities on coral reefs. Increasingly, these fish are being targeted by fishermen, and resultant declines in biomass and abundance may have severe consequences for the dynamics and regeneration of coral reefs. However, the impact of overfishing extends beyond declining fish stocks. It can also lead to demographic changes within species populations where mean body size is reduced. The effect of reduced mean body size on population dynamics is well described in literature but virtually no information exists on how this may influence important ecological functions. The study investigated how one important function, scraping (i.e., the capacity to remove algae and open up bare substratum for coral larval settlement), by three common species of parrotfishes ( Scarus niger, Chlorurus sordidus, and Chlorurus strongylocephalus) on coral reefs at Zanzibar (Tanzania) was influenced by the size of individual fishes. There was a non-linear relationship between body size and scraping function for all species examined, and impact through scraping was also found to increase markedly when fish reached a size of 15 20 cm. Thus, coral reefs which have a high abundance and biomass of parrotfish may nonetheless be functionally impaired if dominated by small-sized individuals. Reductions in mean body size within parrotfish populations could, therefore, have functional impacts on coral reefs that previously have been overlooked.

  17. Identification of MarvelD3 as a tight junction-associated transmembrane protein of the occludin family

    Directory of Open Access Journals (Sweden)

    Balda Maria S

    2009-12-01

    Full Text Available Abstract Background Tight junctions are an intercellular adhesion complex of epithelial and endothelial cells, and form a paracellular barrier that restricts the diffusion of solutes on the basis of size and charge. Tight junctions are formed by multiprotein complexes containing cytosolic and transmembrane proteins. How these components work together to form functional tight junctions is still not well understood and will require a complete understanding of the molecular composition of the junction. Results Here we identify a new transmembrane component of tight junctions: MarvelD3, a four-span transmembrane protein. Its predicted transmembrane helices form a Marvel (MAL and related proteins for vesicle traffic and membrane link domain, a structural motif originally discovered in proteins involved in membrane apposition and fusion events, such as the tight junction proteins occludin and tricellulin. In mammals, MarvelD3 is expressed as two alternatively spliced isoforms. Both isoforms exhibit a broad tissue distribution and are expressed by different types of epithelial as well as endothelial cells. MarvelD3 co-localises with occludin at tight junctions in intestinal and corneal epithelial cells. RNA interference experiments in Caco-2 cells indicate that normal MarvelD3 expression is not required for the formation of functional tight junctions but depletion results in monolayers with increased transepithelial electrical resistance. Conclusions Our data indicate that MarvelD3 is a third member of the tight junction-associated occludin family of transmembrane proteins. Similar to occludin, normal expression of MarvelD3 is not essential for the formation of functional tight junctions. However, MarvelD3 functions as a determinant of epithelial paracellular permeability properties.

  18. Structure modeling and mutational analysis of gap junction beta 2 ...

    African Journals Online (AJOL)

    Yomi

    2012-04-03

    Apr 3, 2012 ... Three dimensional (3 D) structure is very useful for understanding biological functions. Gap junction beta 2 (GJB2), human gene encoding for gap junction beta 2 protein is involved in ... Research in deafness became real.

  19. Effect Size Measures for Differential Item Functioning in a Multidimensional IRT Model

    Science.gov (United States)

    Suh, Youngsuk

    2016-01-01

    This study adapted an effect size measure used for studying differential item functioning (DIF) in unidimensional tests and extended the measure to multidimensional tests. Two effect size measures were considered in a multidimensional item response theory model: signed weighted P-difference and unsigned weighted P-difference. The performance of…

  20. Concatenated logic circuits based on a three-way DNA junction: a keypad-lock security system with visible readout and an automatic reset function.

    Science.gov (United States)

    Chen, Junhua; Zhou, Shungui; Wen, Junlin

    2015-01-07

    Concatenated logic circuits operating as a biocomputing keypad-lock security system with an automatic reset function have been successfully constructed on the basis of toehold-mediated strand displacement and three-way-DNA-junction architecture. In comparison with previously reported keypad locks, the distinctive advantage of the proposed security system is that it can be reset and cycled spontaneously a large number of times without an external stimulus, thus making practical applications possible. By the use of a split-G-quadruplex DNAzyme as the signal reporter, the output of the keypad lock can be recognized readily by the naked eye. The "lock" is opened only when the inputs are introduced in an exact order. This requirement provides defense against illegal invasion to protect information at the molecular scale. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Beyond Gap Junction Channel Function: the Expression of Cx43 Contributes to Aldosterone-Induced Mesangial Cell Proliferation via the ERK1/2 and PKC Pathways

    Directory of Open Access Journals (Sweden)

    Aiqing Zhang

    2015-06-01

    Full Text Available Aims: This study aimed to explore the precise mechanism and signaling pathways of mesangial cell (MC proliferation from a new point of view considering Connexin 43 (Cx43. Methods: MC proliferation was measured by the incorporation of 3H-thymidine (3H-TdR. Cx43 was over-expressed in MC cells using lipofectamine 2000, and the expression level was tested with reverse transcription-polymerase chain reaction (RT-PCR and Western blot analyses. The gap junction channel function was explored by Lucifer Yellow scrape loading and dye transfer (SLDT, and the intracellular calcium concentrations ([Ca2+]i were characterized by confocal microscopy on cells loaded with Fura-3/AM. Results: There was an inverse correlation between Cx43 expression and MC proliferation (P0.05. Our data also showed that the mineralcorticoid receptor (MR antagonist spironolactone, ERK1/2 inhibitor PD98059 and PKC inhibitor GF109203X could attenuate the down-regulation of Cx43 expression in Aldo-induced MC proliferation; however, the PI3K inhibitor LY294002 could block MC proliferation without affecting Cx43 expression at either the mRNA or protein level. In addition, Aldo promoted MC proliferation in parallel with increasing [Ca2+]i (PConclusions: Our study provides preliminary evidence that Cx43 is an important regulator of Aldo-promoted MC proliferation. Furthermore, reduced Cx43 expression promoted MC proliferation independent of the gap junction channel function, and this process might be mediated through the ERK1/2- and PKC-dependent pathways.

  2. Functional assessment of gap junctions in monolayer and three-dimensional cultures of human tendon cells using fluorescence recovery after photobleaching

    OpenAIRE

    Kuzma-Kuzniarska, Maria; Yapp, Clarence; Pearson-Jones, Thomas W.; Jones, Andrew K.; Hulley, Philippa A.

    2014-01-01

    Gap junction-mediated intercellular communication influences a variety of cellular activities. In tendons, gap junctions modulate collagen production, are involved in strain-induced cell death, and are involved in the response to mechanical stimulation. The aim of the present study was to investigate gap junction-mediated intercellular communication in healthy human tendon-derived cells using fluorescence recovery after photobleaching (FRAP). The FRAP is a noninvasive technique that allows qu...

  3. Decomposition of Atmospheric Aerosol Phase Function by Particle Size and Morphology via Single Particle Scattering Measurements

    Science.gov (United States)

    Aptowicz, K. B.; Pan, Y.; Martin, S.; Fernandez, E.; Chang, R.; Pinnick, R. G.

    2013-12-01

    We report upon an experimental approach that provides insight into how particle size and shape affect the scattering phase function of atmospheric aerosol particles. Central to our approach is the design of an apparatus that measures the forward and backward scattering hemispheres (scattering patterns) of individual atmospheric aerosol particles in the coarse mode range. The size and shape of each particle is discerned from the corresponding scattering pattern. In particular, autocorrelation analysis is used to differentiate between spherical and non-spherical particles, the calculated asphericity factor is used to characterize the morphology of non-spherical particles, and the integrated irradiance is used for particle sizing. We found the fraction of spherical particles decays exponentially with particle size, decreasing from 11% for particles on the order of 1 micrometer to less than 1% for particles over 5 micrometer. The average phase functions of subpopulations of particles, grouped by size and morphology, are determined by averaging their corresponding scattering patterns. The phase functions of spherical and non-spherical atmospheric particles are shown to diverge with increasing size. In addition, the phase function of non-spherical particles is found to vary little as a function of the asphericity factor.

  4. Molecular electronic junction transport

    DEFF Research Database (Denmark)

    Solomon, Gemma C.; Herrmann, Carmen; Ratner, Mark

    2012-01-01

    Whenasinglemolecule,oracollectionofmolecules,isplacedbetween two electrodes and voltage is applied, one has a molecular transport junction. We discuss such junctions, their properties, their description, and some of their applications. The discussion is qualitative rather than quantitative, and f...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-05-14

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

  6. Resolving Microzooplankton Functional Groups In A Size-Structured Planktonic Model

    Science.gov (United States)

    Taniguchi, D.; Dutkiewicz, S.; Follows, M. J.; Jahn, O.; Menden-Deuer, S.

    2016-02-01

    Microzooplankton are important marine grazers, often consuming a large fraction of primary productivity. They consist of a great diversity of organisms with different behaviors, characteristics, and rates. This functional diversity, and its consequences, are not currently reflected in large-scale ocean ecological simulations. How should these organisms be represented, and what are the implications for their biogeography? We develop a size-structured, trait-based model to characterize a diversity of microzooplankton functional groups. We compile and examine size-based laboratory data on the traits, revealing some patterns with size and functional group that we interpret with mechanistic theory. Fitting the model to the data provides parameterizations of key rates and properties, which we employ in a numerical ocean model. The diversity of grazing preference, rates, and trophic strategies enables the coexistence of different functional groups of micro-grazers under various environmental conditions, and the model produces testable predictions of the biogeography.

  7. Transport properties of molecular junctions

    CERN Document Server

    Zimbovskaya, Natalya A

    2013-01-01

    A comprehensive overview of the physical mechanisms that control electron transport and the characteristics of metal-molecule-metal (MMM) junctions is presented. As far as possible, methods and formalisms presented elsewhere to analyze electron transport through molecules are avoided. This title introduces basic concepts—a description of the electron transport through molecular junctions—and briefly describes relevant experimental methods. Theoretical methods commonly used to analyze the electron transport through molecules are presented. Various effects that manifest in the electron transport through MMMs, as well as the basics of density-functional theory and its applications to electronic structure calculations in molecules are presented. Nanoelectronic applications of molecular junctions and similar systems are discussed as well. Molecular electronics is a diverse and rapidly growing field. Transport Properties of Molecular Junctions presents an up-to-date survey of the field suitable for researchers ...

  8. Phenomenological approach to bistable behavior of Josephson junctions

    International Nuclear Information System (INIS)

    Nishi, K.; Nara, S.; Hamanaka, K.

    1985-01-01

    The interaction of unbiased Josephson junction with external electromagnetic field in the presence of externally applied uniform magnetic field is theoretically examined by means of phenomenological treatment. It is proposed that an irradiated junction with suitably chosen parameters shows a bistable behavior of voltage across the junction as a function of the radiation intensity

  9. Motor unit recruitment by size does not provide functional advantages for motor performance.

    Science.gov (United States)

    Dideriksen, Jakob L; Farina, Dario

    2013-12-15

    It is commonly assumed that the orderly recruitment of motor units by size provides a functional advantage for the performance of movements compared with a random recruitment order. On the other hand, the excitability of a motor neuron depends on its size and this is intrinsically linked to its innervation number. A range of innervation numbers among motor neurons corresponds to a range of sizes and thus to a range of excitabilities ordered by size. Therefore, if the excitation drive is similar among motor neurons, the recruitment by size is inevitably due to the intrinsic properties of motor neurons and may not have arisen to meet functional demands. In this view, we tested the assumption that orderly recruitment is necessarily beneficial by determining if this type of recruitment produces optimal motor output. Using evolutionary algorithms and without any a priori assumptions, the parameters of neuromuscular models were optimized with respect to several criteria for motor performance. Interestingly, the optimized model parameters matched well known neuromuscular properties, but none of the optimization criteria determined a consistent recruitment order by size unless this was imposed by an association between motor neuron size and excitability. Further, when the association between size and excitability was imposed, the resultant model of recruitment did not improve the motor performance with respect to the absence of orderly recruitment. A consistent observation was that optimal solutions for a variety of criteria of motor performance always required a broad range of innervation numbers in the population of motor neurons, skewed towards the small values. These results indicate that orderly recruitment of motor units in itself does not provide substantial functional advantages for motor control. Rather, the reason for its near-universal presence in human movements is that motor functions are optimized by a broad range of innervation numbers.

  10. Functional-dependent and size-dependent uptake of nanoparticles in PC12

    International Nuclear Information System (INIS)

    Sakai, N; Matsui, Y; Nakayama, A; Yoneda, M; Tsuda, A

    2011-01-01

    It is suggested that the uptake of nanoparticles is changed by the particle size or the surface modification. In this study, we quantified the uptake of nanoparticles in PC12 cells exposed Quantum Dots with different surface modification or fluorescent polystyrene particles with different particle size. The PC12 cells were exposed three types of the Quantum Dots (carboxyl base-functionalized, amino base-functionalized or non-base-functionalized) or three types of the fluorescent particles (22 nm, 100 nm or 1000 nm) for 3 hours. The uptake of the nanoparticles was quantified with a spectrofluorophotometer. The carboxyl base-functionalized Quantum Dots were considerably taken up by the cells than the non-base-functionalized Quantum Dots. Conversely, the amino base-functionalized Quantum Dots were taken up by the cells less frequently than the non-base-functionalized Quantum Dots. The particle number of the 22 nm-nanoparticles taken up by the cells was about 53 times higher than the 100 nm-particles. However, the particle weight of the 100 nm-particles taken up by the cells was higher than that of the 22 nm-nanoparticles. The 1000 nm-particles were adhered to the cell membrane, but they were little taken up by the cells. We concluded that nanoparticles can be taken up nerve cells in functional-dependent and size-dependent manners.

  11. Mortality as a bivariate function of age and size in indeterminate growers

    DEFF Research Database (Denmark)

    Colchero, Fernando; Schaible, Ralf

    2014-01-01

    Mortality in organisms that grow indefinitely, known as indeterminate growers, is thought to be driven primarily by size. However, a number of ageing mechanisms also act as functions of age. Thus, to explain mortality in these species, both size and age need to be explicitly modelled. Here we...... contribution of age, as a proxy for chronological deterioration, is of typical senescence; while a seemingly senescent population can have underlying age-related negative senescence, which is, however, overcome by negative underlying size effects. We show how inference about these unobserved processes can...

  12. Planar Josephson tunnel junctions in a transverse magnetic field

    DEFF Research Database (Denmark)

    Monacoa, R.; Aarøe, Morten; Mygind, Jesper

    2007-01-01

    demagnetization effects imposed by the tunnel barrier and electrodes geometry are important. Measurements of the junction critical current versus magnetic field in planar Nb-based high-quality junctions with different geometry, size, and critical current density show that it is advantageous to use a transverse......Traditionally, since the discovery of the Josephson effect in 1962, the magnetic diffraction pattern of planar Josephson tunnel junctions has been recorded with the field applied in the plane of the junction. Here we discuss the static junction properties in a transverse magnetic field where...

  13. Kidney function and size in normal subjects before and during growth hormone administration for one week

    DEFF Research Database (Denmark)

    Gammelgaard, Jens; Orskov, H; Andersen, A R

    1981-01-01

    Kidney function and size were studied in seven normal male subjects before and after administration of highly purified human growth hormone for 1 week. Glomerular filtration rate, renal plasma flow (steady-state infusion technique with urinary collections using 125I-iothalamate and 131I-hippuran)......Kidney function and size were studied in seven normal male subjects before and after administration of highly purified human growth hormone for 1 week. Glomerular filtration rate, renal plasma flow (steady-state infusion technique with urinary collections using 125I-iothalamate and 131I...

  14. Three-point correlation functions of giant magnons with finite size

    International Nuclear Information System (INIS)

    Ahn, Changrim; Bozhilov, Plamen

    2011-01-01

    We compute holographic three-point correlation functions or structure constants of a zero-momentum dilaton operator and two (dyonic) giant magnon string states with a finite-size length in the semiclassical approximation. We show that the semiclassical structure constants match exactly with the three-point functions between two su(2) magnon single trace operators with finite size and the Lagrangian in the large 't Hooft coupling constant limit. A special limit J>>√(λ) of our result is compared with the relevant result based on the Luescher corrections.

  15. Junction and circuit fabrication

    International Nuclear Information System (INIS)

    Jackel, L.D.

    1980-01-01

    Great strides have been made in Josephson junction fabrication in the four years since the first IC SQUID meeting. Advances in lithography have allowed the production of devices with planar dimensions as small as a few hundred angstroms. Improved technology has provided ultra-high sensitivity SQUIDS, high-efficiency low-noise mixers, and complex integrated circuits. This review highlights some of the new fabrication procedures. The review consists of three parts. Part 1 is a short summary of the requirements on junctions for various applications. Part 2 reviews intergrated circuit fabrication, including tunnel junction logic circuits made at IBM and Bell Labs, and microbridge radiation sources made at SUNY at Stony Brook. Part 3 describes new junction fabrication techniques, the major emphasis of this review. This part includes a discussion of small oxide-barrier tunnel junctions, semiconductor barrier junctions, and microbridge junctions. Part 3 concludes by considering very fine lithography and limitations to miniaturization. (orig.)

  16. Functional, size and taxonomic diversity of fish along a depth gradient in the deep sea.

    Science.gov (United States)

    Mindel, Beth L; Neat, Francis C; Trueman, Clive N; Webb, Thomas J; Blanchard, Julia L

    2016-01-01

    Biodiversity is well studied in ecology and the concept has been developed to include traits of species, rather than solely taxonomy, to better reflect the functional diversity of a system. The deep sea provides a natural environmental gradient within which to study changes in different diversity metrics, but traits of deep-sea fish are not widely known, hampering the application of functional diversity to this globally important system. We used morphological traits to determine the functional richness and functional divergence of demersal fish assemblages along the continental slope in the Northeast Atlantic, at depths of 300-2,000 m. We compared these metrics to size diversity based on individual body size and species richness. Functional richness and size diversity showed similar patterns, with the highest diversity at intermediate depths; functional divergence showed the opposite pattern, with the highest values at the shallowest and deepest parts of the study site. Species richness increased with depth. The functional implications of these patterns were deduced by examining depth-related changes in morphological traits and the dominance of feeding guilds as illustrated by stable isotope analyses. The patterns in diversity and the variation in certain morphological traits can potentially be explained by changes in the relative dominance of pelagic and benthic feeding guilds. All measures of diversity examined here suggest that the deep areas of the continental slope may be equally or more diverse than assemblages just beyond the continental shelf.

  17. Functional, size and taxonomic diversity of fish along a depth gradient in the deep sea

    Directory of Open Access Journals (Sweden)

    Beth L. Mindel

    2016-09-01

    Full Text Available Biodiversity is well studied in ecology and the concept has been developed to include traits of species, rather than solely taxonomy, to better reflect the functional diversity of a system. The deep sea provides a natural environmental gradient within which to study changes in different diversity metrics, but traits of deep-sea fish are not widely known, hampering the application of functional diversity to this globally important system. We used morphological traits to determine the functional richness and functional divergence of demersal fish assemblages along the continental slope in the Northeast Atlantic, at depths of 300–2,000 m. We compared these metrics to size diversity based on individual body size and species richness. Functional richness and size diversity showed similar patterns, with the highest diversity at intermediate depths; functional divergence showed the opposite pattern, with the highest values at the shallowest and deepest parts of the study site. Species richness increased with depth. The functional implications of these patterns were deduced by examining depth-related changes in morphological traits and the dominance of feeding guilds as illustrated by stable isotope analyses. The patterns in diversity and the variation in certain morphological traits can potentially be explained by changes in the relative dominance of pelagic and benthic feeding guilds. All measures of diversity examined here suggest that the deep areas of the continental slope may be equally or more diverse than assemblages just beyond the continental shelf.

  18. Assessment of relative individual renal function based on DMSA uptake corrected for renal size

    International Nuclear Information System (INIS)

    Estorch, M.; Camacho, V.; Tembl, A.; Mena, I.; Hernandez, A.; Flotats, A.; Carrio, I.; Torres, G.; Prat, L.

    2002-01-01

    Decreased relative renal DMSA uptake can be a consequence of abnormal kidney size, associated with normal or impaired renal function. The quantification of relative renal function based on DMSA uptake in both kidneys is an established method for the assessment of individual renal function. Aim: To assess relative renal function by means of quantification of renal DMSA uptake corrected for kidney size. Results were compared with relative renal DMSA uptake without size correction, and were validated against the absolute renal DMSA uptake. Material and Methods: Four-hundred-forty-four consecutive patients (147 adults, mean age 14 years) underwent a DMSA study for several renal diseases. The relative renal function, based on the relative DMSA uptake uncorrected and corrected for renal size, and the absolute renal DMSA uptake were calculated. In order to relate the relative DMSA uptake uncorrected and corrected for renal size with the absolute DMSA uptake, subtraction of uncorrected (SU) and corrected (SC) relative uptake percentages of each pair of kidneys was obtained, and these values were correlated to the matched subtraction percentages of absolute uptake (SA). If the individual relative renal function is normal (45%-55%), the subtraction value is less or equal to 10%. Results: In 227 patients (51%) the relative renal DMSA uptake value was normal either uncorrected or corrected for renal size (A), and in 149 patients (34%) it was abnormal by both quantification methods (B). Seventy-seven patients (15%) had the relative renal DMSA uptake abnormal only by the uncorrected method (C). Subtraction value of absolute DMSA uptake percentages was not significantly different of subtraction value of relative DMSA uptake percentages corrected for renal size when relative uncorrected uptake was abnormal and corrected normal. where * p<0.0001, and p=NS. Conclusion: When uncorrected and corrected relative DMSA uptake are abnormal, the absolute uptake is also impaired, while when

  19. Defective functional connectivity between posterior hypothalamus and regions of the diencephalic-mesencephalic junction in chronic cluster headache.

    Science.gov (United States)

    Ferraro, Stefania; Nigri, Anna; Bruzzone, Maria Grazia; Brivio, Luca; Proietti Cecchini, Alberto; Verri, Mattia; Chiapparini, Luisa; Leone, Massimo

    2018-01-01

    Objective We tested the hypothesis of a defective functional connectivity between the posterior hypothalamus and diencephalic-mesencephalic regions in chronic cluster headache based on: a) clinical and neuro-endocrinological findings in cluster headache patients; b) neuroimaging findings during cluster headache attacks; c) neuroimaging findings in drug-refractory chronic cluster headache patients improved after successful deep brain stimulation. Methods Resting state functional magnetic resonance imaging, associated with a seed-based approach, was employed to investigate the functional connectivity of the posterior hypothalamus in chronic cluster headache patients (n = 17) compared to age and sex-matched healthy subjects (n = 16). Random-effect analyses were performed to study differences between patients and controls in ipsilateral and contralateral-to-the-pain posterior hypothalamus functional connectivity. Results Cluster headache patients showed an increased functional connectivity between the ipsilateral posterior hypothalamus and a number of diencephalic-mesencephalic structures, comprising ventral tegmental area, dorsal nuclei of raphe, and bilateral substantia nigra, sub-thalamic nucleus, and red nucleus ( p cluster headache patients mainly involves structures that are part of (i.e. ventral tegmental area, substantia nigra) or modulate (dorsal nuclei of raphe, sub-thalamic nucleus) the midbrain dopaminergic systems. The midbrain dopaminergic systems could play a role in cluster headache pathophysiology and in particular in the chronicization process. Future studies are needed to better clarify if this finding is specific to cluster headache or if it represents an unspecific response to chronic pain.

  20. Migrate small, sound big: functional constraints on body size promote tracheal elongation in cranes.

    Science.gov (United States)

    Jones, M R; Witt, C C

    2014-06-01

    Organismal traits often represent the outcome of opposing selection pressures. Although social or sexual selection can cause the evolution of traits that constrain function or survival (e.g. ornamental feathers), it is unclear how the strength and direction of selection respond to ecological shifts that increase the severity of the constraint. For example, reduced body size might evolve by natural selection to enhance flight performance in migratory birds, but social or sexual selection favouring large body size may provide a countervailing force. Tracheal elongation is a potential outcome of these opposing pressures because it allows birds to convey an auditory signal of exaggerated body size. We predicted that the evolution of migration in cranes has coincided with a reduction in body size and a concomitant intensification of social or sexual selection for apparent large body size via tracheal elongation. We used a phylogenetic comparative approach to examine the relationships among migration distance, body mass and trachea length in cranes. As predicted, we found that migration distance correlated negatively with body size and positively with proportional trachea length. This result was consistent with our hypothesis that evolutionary reductions in body size led to intensified selection for trachea length. The most likely ultimate causes of intensified positive selection on trachea length are the direct benefits of conveying a large body size in intraspecific contests for mates and territories. We conclude that the strength of social or sexual selection on crane body size is linked to the degree of functional constraint. © 2014 The Authors. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

  1. Superoperator nonequilibrium Green's function theory of many-body systems; applications to charge transfer and transport in open junctions

    International Nuclear Information System (INIS)

    Harbola, U.; Mukamel, S.

    2008-01-01

    Nonequilibrium Green's functions provide a powerful tool for computing the dynamical response and particle exchange statistics of coupled quantum systems. We formulate the theory in terms of the density matrix in Liouville space and introduce superoperator algebra that greatly simplifies the derivation and the physical interpretation of all quantities. Expressions for various observables are derived directly in real time in terms of superoperator nonequilibrium Green's functions (SNGF), rather than the artificial time-loop required in Schwinger's Hilbert-space formulation. Applications for computing interaction energies, charge densities, average currents, current induced fluorescence, electroluminescence and current fluctuation (electron counting) statistics are discussed

  2. Pore size determination using normalized J-function for different hydraulic flow units

    Directory of Open Access Journals (Sweden)

    Ali Abedini

    2015-06-01

    Full Text Available Pore size determination of hydrocarbon reservoirs is one of the main challenging areas in reservoir studies. Precise estimation of this parameter leads to enhance the reservoir simulation, process evaluation, and further forecasting of reservoir behavior. Hence, it is of great importance to estimate the pore size of reservoir rocks with an appropriate accuracy. In the present study, a modified J-function was developed and applied to determine the pore radius in one of the hydrocarbon reservoir rocks located in the Middle East. The capillary pressure data vs. water saturation (Pc–Sw as well as routine reservoir core analysis include porosity (φ and permeability (k were used to develop the J-function. First, the normalized porosity (φz, the rock quality index (RQI, and the flow zone indicator (FZI concepts were used to categorize all data into discrete hydraulic flow units (HFU containing unique pore geometry and bedding characteristics. Thereafter, the modified J-function was used to normalize all capillary pressure curves corresponding to each of predetermined HFU. The results showed that the reservoir rock was classified into five separate rock types with the definite HFU and reservoir pore geometry. Eventually, the pore radius for each of these HFUs was determined using a developed equation obtained by normalized J-function corresponding to each HFU. The proposed equation is a function of reservoir rock characteristics including φz, FZI, lithology index (J*, and pore size distribution index (ɛ. This methodology used, the reservoir under study was classified into five discrete HFU with unique equations for permeability, normalized J-function and pore size. The proposed technique is able to apply on any reservoir to determine the pore size of the reservoir rock, specially the one with high range of heterogeneity in the reservoir rock properties.

  3. The penetration of fibrous media by aerosols as a function of particle size

    Energy Technology Data Exchange (ETDEWEB)

    Dyment, J.

    1963-11-15

    This paper is concerned with the accurate experimental determination of the penetration of fibrous filter media by aerosols as a function of particle size, a topic about which previous papers give partial and conflicting data. in the present work, a heterogeneous sodium chloride aerosol was sampled before and after passing through the glass fiber filter medium by means of an electrostatic precipitator and the samples were examined under the electron microscope; the relation between particle size and penetration was derives at different gas velocities by comparison of the size distribution of the filtered and unfiltered clouds. As an extension of this work, size analyses have been made of plutonium aerosols occurring in glove boxes and enclosures during typical working operations. This information is considered in relation to the penetration of plutonium and other high density aerosol materials through filters. (auth)

  4. Soot Particle Size Distribution Functions in a Turbulent Non-Premixed Ethylene-Nitrogen Flame

    KAUST Repository

    Boyette, Wesley

    2017-02-21

    A scanning mobility particle sizer with a nano differential mobility analyzer was used to measure nanoparticle size distribution functions in a turbulent non-premixed flame. The burner utilizes a premixed pilot flame which anchors a C2H4/N2 (35/65) central jet with ReD = 20,000. Nanoparticles in the flame were sampled through a N2-filled tube with a 500- μm orifice. Previous studies have shown that insufficient dilution of the nanoparticles can lead to coagulation in the sampling line and skewed particle size distribution functions. A system of mass flow controllers and valves were used to vary the dilution ratio. Single-stage and two-stage dilution systems were investigated. A parametric study on the effect of the dilution ratio on the observed particle size distribution function indicates that particle coagulation in the sampling line can be eliminated using a two-stage dilution process. Carbonaceous nanoparticle (soot) concentration particle size distribution functions along the flame centerline at multiple heights in the flame are presented. The resulting distributions reveal a pattern of increasing mean particle diameters as the distance from the nozzle along the centerline increases.

  5. Power and Sample Size Calculations for Logistic Regression Tests for Differential Item Functioning

    Science.gov (United States)

    Li, Zhushan

    2014-01-01

    Logistic regression is a popular method for detecting uniform and nonuniform differential item functioning (DIF) effects. Theoretical formulas for the power and sample size calculations are derived for likelihood ratio tests and Wald tests based on the asymptotic distribution of the maximum likelihood estimators for the logistic regression model.…

  6. Soot Particle Size Distribution Functions in a Turbulent Non-Premixed Ethylene-Nitrogen Flame

    KAUST Repository

    Boyette, Wesley; Chowdhury, Snehaunshu; Roberts, William L.

    2017-01-01

    A scanning mobility particle sizer with a nano differential mobility analyzer was used to measure nanoparticle size distribution functions in a turbulent non-premixed flame. The burner utilizes a premixed pilot flame which anchors a C2H4/N2 (35/65) central jet with ReD = 20,000. Nanoparticles in the flame were sampled through a N2-filled tube with a 500- μm orifice. Previous studies have shown that insufficient dilution of the nanoparticles can lead to coagulation in the sampling line and skewed particle size distribution functions. A system of mass flow controllers and valves were used to vary the dilution ratio. Single-stage and two-stage dilution systems were investigated. A parametric study on the effect of the dilution ratio on the observed particle size distribution function indicates that particle coagulation in the sampling line can be eliminated using a two-stage dilution process. Carbonaceous nanoparticle (soot) concentration particle size distribution functions along the flame centerline at multiple heights in the flame are presented. The resulting distributions reveal a pattern of increasing mean particle diameters as the distance from the nozzle along the centerline increases.

  7. Children’s Belief- and Desire-reasoning in the Temporopartietal Junction: Evidence for Specialization from Functional Near-Infrared Spectroscopy

    Directory of Open Access Journals (Sweden)

    Lindsay Caroline Bowman

    2015-10-01

    Full Text Available Behaviorally, children’s explicit theory-of-mind (ToM proceeds in a progression of mental-state understandings: developmentally, children demonstrate accurate explicit desire-reasoning before accurate explicit belief-reasoning. Given its robust and cross-cultural nature, we hypothesize this progression may be paced in part by maturation/specialization of the brain. Neuroimaging research demonstrates that the right temporoparietal junction (TPJ becomes increasingly selective for ToM reasoning as children age, and as their ToM improves. But this research has narrowly focused on beliefs or on undifferentiated mental-states. A recent ERP study in children included a critical contrast to desire-reasoning, and demonstrated that right posterior potentials differentiated belief-reasoning from desire-reasoning. Taken together, the literature suggests that children’s desire-belief progression may be paced by specialization of the right TPJ for belief-reasoning specifically, beyond desire-reasoning. In the present study, we tested this hypothesis directly by examining children’s belief- and desire-reasoning using functional near-infrared spectroscopy (fNIRS in conjunction with structural MRI to pinpoint brain activation in the right TPJ. Results showed greatest activation in the right TPJ for belief-reasoning, beyond desire-reasoning, and beyond non-mental reasoning (control. Findings replicate and critically extend prior ERP results, and provide clear evidence for a specific neural mechanism underlying children’s progression from understanding desires to understanding beliefs.

  8. Budding yeast mms4 is epistatic with rad52 and the function of Mms4 can be replaced by a bacterial Holliday junction resolvase.

    Science.gov (United States)

    Odagiri, Nao; Seki, Masayuki; Onoda, Fumitoshi; Yoshimura, Akari; Watanabe, Sei; Enomoto, Takemi

    2003-03-01

    MMS4 of Saccharomyces cerevisiae was originally identified as the gene responsible for one of the collection of methyl methanesulfonate (MMS)-sensitive mutants, mms4. Recently it was identified as a synthetic lethal gene with an SGS1 mutation. Epistatic analyses revealed that MMS4 is involved in a pathway leading to homologous recombination requiring Rad52 or in the recombination itself, in which SGS1 is also involved. MMS sensitivity of mms4 but not sgs1, was suppressed by introducing a bacterial Holliday junction (HJ) resolvase, RusA. The frequencies of spontaneously occurring unequal sister chromatid recombination (SCR) and loss of marker in the rDNA in haploid mms4 cells and interchromosomal recombination between heteroalleles in diploid mms4 cells were essentially the same as those of wild-type cells. Although UV- and MMS-induced interchromosomal recombination was defective in sgs1 diploid cells, hyper-induction of interchromosomal recombination was observed in diploid mms4 cells, indicating that the function of Mms4 is dispensable for this type of recombination.

  9. [Effects of Chinese herbal compound for supplementing qi and activating blood circulation on actin, Cx43 expressions and gap junctional intercellular communication functions of myocardial cells in patients with Coxsackie virus B 3 viral myocarditis].

    Science.gov (United States)

    Zhang, Ming-xue; He, Wei; Gu, Ping

    2010-08-01

    To observe the effect of Chinese herbal compound for supplementing qi and activating blood circulation (CHC) on the gap junctional intercellular communication (GJIC) function of myocardial cells in patients with Coxsackie virus B 3 (CVB3) viral myocarditis. Expressions of actin and connexin43 (Cx43) in myocardial cells of patients arranged in three groups (the normal control group, the viral infected group and the CHC treated group) were detected by immunohistochemical method; the fluorescence photobleaching recovery rate of cells was detected by laser scanning confocal microscope. As compared with the viral infected group, the expressions of actin and Cx43 were increased and the GJIC function was improved in the CHC treated group. CHC could antagonize viral injury on skeleton protein, and repair the structure of gap junction channel to improve the GJIC function of myocardial cells after being attacked by CVB3.

  10. MODELING PARTICLE SIZE DISTRIBUTION IN HETEROGENEOUS POLYMERIZATION SYSTEMS USING MULTIMODAL LOGNORMAL FUNCTION

    Directory of Open Access Journals (Sweden)

    J. C. Ferrari

    Full Text Available Abstract This work evaluates the usage of the multimodal lognormal function to describe Particle Size Distributions (PSD of emulsion and suspension polymerization processes, including continuous reactions with particle re-nucleation leading to complex multimodal PSDs. A global optimization algorithm, namely Particle Swarm Optimization (PSO, was used for parameter estimation of the proposed model, minimizing the objective function defined by the mean squared errors. Statistical evaluation of the results indicated that the multimodal lognormal function could describe distinctive features of different types of PSDs with accuracy and consistency.

  11. Estimation by radiation inactivation of the size of functional units governing Sendai and influenza virus fusion

    International Nuclear Information System (INIS)

    Bundo-Morita, K.; Gibson, S.; Lenard, J.

    1987-01-01

    The target sizes associated with fusion and hemolysis carried out by Sendai virus envelope glycoproteins were determined by radiation inactivation analysis. The target size for influenza virus mediated fusion with erythrocyte ghosts at pH 5.0 was also determined for comparison. Sendai-mediated fusion with erythrocyte ghosts at pH 7.0 was likewise inactivated exponentially with increasing radiation dose, yielding a target size of 60 +/- 6 kDa, a value consistent with the molecular weight of a single F-protein molecule. The inactivation curve for Sendai-mediated fusion with cardiolipin liposomes at pH 7.0, however, was more complex. Assuming a multiple target-single hit model, the target consisted of 2-3 units of ca. 60 kDa each. A similar target was seen if the liposome contained 10% gangliosides or if the reaction was measured at pH 5.0, suggesting that fusion occurred by the same mechanism at high and low pH. A target size of 261 +/- 48 kDa was found for Sendai-induced hemolysis, in contrast with influenza, which had a more complex target size for this activity. Sendai virus fusion thus occurs by different mechanisms depending upon the nature of the target membrane, since it is mediated by different functional units. Hemolysis is mediated by a functional unit different from that associated with erythrocyte ghost fusion or with cardiolipin liposome fusion

  12. Josephson junction arrays

    International Nuclear Information System (INIS)

    Bindslev Hansen, J.; Lindelof, P.E.

    1985-01-01

    In this review we intend to cover recent work involving arrays of Josephson junctions. The work on such arrays falls naturally into three main areas of interest: 1. Technical applications of Josephson junction arrays for high-frequency devices. 2. Experimental studies of 2-D model systems (Kosterlitz-Thouless phase transition, commensurate-incommensurate transition in frustrated (flux) lattices). 3. Investigations of phenomena associated with non-equilibrium superconductivity in and around Josephson junctions (with high current density). (orig./BUD)

  13. Characteristic of Water Pervaporation Using Hydrophilic Composite Membrane Containing Functional Nano Sized NaA zeolites

    International Nuclear Information System (INIS)

    Oh, Duckkyu; Lee, Yongtaek

    2013-01-01

    The NaA zeolite particles were dispersed in a poly(vinyl alcohol) (PVA) matrix to prepare a composite membrane. The nano sized zeolite particles of NaA were synthesized in the laboratory and the mean size was approximately 60 nm. Pervaporation characteristics such as a permeation flux and a separation factor were investigated using the membrane as a function of the feed concentration from 0.01 to 0.05 mole fraction and the weight % of NaA particles between 0 wt% and 5 wt% in the membrane. Also, the micro sized particles of 5 mm were dispersed in the membrane for a comparison purpose. When the ethanol concentration in the feed solution was 0.01 mole fraction, the flux of water significantly increased from 600 g/m 2 /hr to 2000 g/m 2 /hr as the content of the nano NaA particles in the membrane increased from 0 wt% to 5 wt%, while the NaA particles improved the separation factor from 1.5 to 7.9. When the flux of water through the membrane containing nano sized particles was roughly 15% increased compared to the micro sized particles, whereas the separation factor of water was found to be approximately 5% increased. It can be said that the role of the nano sized NaA particles is quite important since both the flux and the separation factor are strongly affected

  14. Sapwood area ofPinus contorta stands as a function of mean size and density.

    Science.gov (United States)

    Long, James N; Dean, Thomas J

    1986-09-01

    An indirect test of the relationship between leaf area and the combination of mean size and density is made in stands of lodgepole pine (Pinus contorta Dougl.). Total sapwood cross-sectional area of these stands is a function of the product of density and mean diameter raised to an exponent of about 1.6. Results from other studies, representing four species, suggest that this relationship between sapwood area and the combination of mean size and density may be general. The implications of the relationship are discussed in the context of evapotranspiration, competition and self-thinning.

  15. The Functionalization, Size Control and Properties of Metal-Organic Frameworks

    DEFF Research Database (Denmark)

    Xu, Hui; Iversen, Bo Brummerstedt

    Recent years, Metal-Organic Framework (MOF) materials have drawn great attentions due to their potential applications in gas sorption/separation and luminescent sensing. In this dissertation, the recent progress of MOF materials is reviewed, with specific focus on the functionalization, size....... A nanoscale MOF material with controllable size was realized whose morphology has been simulated base on the BFDH method, and the sensing of bacteria endospores was research in detail. We also report the synthesis and sensing of nitroaromatic explosives of a nanoscale MOF material....

  16. Size-dependent error of the density functional theory ionization potential in vacuum and solution.

    Science.gov (United States)

    Sosa Vazquez, Xochitl A; Isborn, Christine M

    2015-12-28

    Density functional theory is often the method of choice for modeling the energetics of large molecules and including explicit solvation effects. It is preferable to use a method that treats systems of different sizes and with different amounts of explicit solvent on equal footing. However, recent work suggests that approximate density functional theory has a size-dependent error in the computation of the ionization potential. We here investigate the lack of size-intensivity of the ionization potential computed with approximate density functionals in vacuum and solution. We show that local and semi-local approximations to exchange do not yield a constant ionization potential for an increasing number of identical isolated molecules in vacuum. Instead, as the number of molecules increases, the total energy required to ionize the system decreases. Rather surprisingly, we find that this is still the case in solution, whether using a polarizable continuum model or with explicit solvent that breaks the degeneracy of each solute, and we find that explicit solvent in the calculation can exacerbate the size-dependent delocalization error. We demonstrate that increasing the amount of exact exchange changes the character of the polarization of the solvent molecules; for small amounts of exact exchange the solvent molecules contribute a fraction of their electron density to the ionized electron, but for larger amounts of exact exchange they properly polarize in response to the cationic solute. In vacuum and explicit solvent, the ionization potential can be made size-intensive by optimally tuning a long-range corrected hybrid functional.

  17. Equivalent Josephson junctions

    International Nuclear Information System (INIS)

    Boyadzhiev, T.L.; ); Semerdzhieva, E.G.; Shukrinov, Yu.M.; Fiziko-Tekhnicheskij Inst., Dushanbe

    2008-01-01

    The magnetic field dependences of critical current are numerically constructed for a long Josephson junction with a shunt- or resistor-type microscopic inhomogeneities and compared to the critical curve of a junction with exponentially varying width. The numerical results show that it is possible to replace the distributed inhomogeneity of a long Josephson junction by an inhomogeneity localized at one of its ends, which has certain technological advantages. It is also shown that the critical curves of junctions with exponentially varying width and inhomogeneities localized at the ends are unaffected by the mixed fluxon-antifluxon distributions of the magnetic flux [ru

  18. Proinflammatory cytokines tumor necrosis factor-alpha and interferon-gamma alter tight junction structure and function in the rat parotid gland Par-C10 cell line.

    Science.gov (United States)

    Baker, Olga J; Camden, Jean M; Redman, Robert S; Jones, Jonathan E; Seye, Cheikh I; Erb, Laurie; Weisman, Gary A

    2008-11-01

    Sjögren's syndrome (SS) is an autoimmune disorder characterized by inflammation and dysfunction of salivary glands, resulting in impaired secretory function. The production of the proinflammatory cytokines tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) is elevated in exocrine glands of patients with SS, although little is known about the effects of these cytokines on salivary epithelial cell functions necessary for saliva secretion, including tight junction (TJ) integrity and the establishment of transepithelial ion gradients. The present study demonstrates that chronic exposure of polarized rat parotid gland (Par-C10) epithelial cell monolayers to TNF-alpha and IFN-gamma decreases transepithelial resistance (TER) and anion secretion, as measured by changes in short-circuit current (I(sc)) induced by carbachol, a muscarinic cholinergic receptor agonist, or UTP, a P2Y(2) nucleotide receptor agonist. In contrast, TNF-alpha and IFN-gamma had no effect on agonist-induced increases in the intracellular calcium concentration [Ca(2+)](i) in Par-C10 cells. Furthermore, treatment of Par-C10 cell monolayers with TNF-alpha and IFN-gamma increased paracellular permeability to normally impermeant proteins, altered cell and TJ morphology, and downregulated the expression of the TJ protein, claudin-1, but not other TJ proteins expressed in Par-C10 cells. The decreases in TER, agonist-induced transepithelial anion secretion, and claudin-1 expression caused by TNF-alpha, but not IFN-gamma, were reversible by incubation of Par-C10 cell monolayers with cytokine-free medium for 24 h, indicating that IFN-gamma causes irreversible inhibition of cellular activities associated with fluid secretion in salivary glands. Our results suggest that cytokine production is an important contributor to secretory dysfunction in SS by disrupting TJ integrity of salivary epithelium.

  19. Measurement of esophago-gastric junction cross-sectional area and distensibility by an endolumenal functional lumen imaging probe for the diagnosis of gastro-esophageal reflux disease.

    Science.gov (United States)

    Tucker, E; Sweis, R; Anggiansah, A; Wong, T; Telakis, E; Knowles, K; Wright, J; Fox, M

    2013-11-01

    Measurement of esophago-gastric junction (EGJ) cross-sectional area (CSA) and distensibility by an Endolumenal Functional Lumen Imaging Probe (EndoFLIP®) may distinguish between gastro-esophageal reflux disease (GERD) patients and healthy volunteers (HV). We aimed to assess the agreement of EndoFLIP® measurements with clinical and physiologic diagnosis of GERD. Twenty-one HV and 18 patients with typical GERD symptoms were studied. After gastroscopy, EGJ CSA, and distensibility were measured by EndoFLIP®. Forty-eight hour esophageal pH monitoring was then performed by a wireless system. The ability of EndoFLIP® to discriminate GERD patient and HVs was assessed. Planned secondary analysis then assessed whether EGJ CSA and distensibility were increased in individuals with pathologic acid exposure. Healthy volunteers were younger and had lower body mass index (BMI; both p < 0.001). Pathologic acid exposure was present in 3/21 (14%) HVs and 9/18 (50%) patients (p = 0.126). At 30 mL EndoFLIP® bag volume, EGJ CSA was higher (p = 0.058) and EGJ distensibility was lower (p = 0.020) in HVs than patients. Secondary analysis showed that EGJ measurements were similar in participants with and without pathologic acid exposure (CSA 98 mm² vs 107 mm²; p = 0.789, distensibility; p = 0.704). An inverse association between BMI and CSA (R² = 0.2758, p = 0.001) and distensibility (R² = 0.2005, p = 0.005) was present. Endolumenal Functional Lumen Imaging Probe is not useful for GERD diagnosis because EGJ CSA and distensibility do not distinguish between HVs and GERD patients defined by clinical presentation or pH measurement. This unexpected result may be due to an important, confounding interaction of obesity. © 2013 John Wiley & Sons Ltd.

  20. Solute-solvent cavity and bridge functions. I. Varying size of the solute

    International Nuclear Information System (INIS)

    Vyalov, I.; Chuev, G.; Georgi, N.

    2014-01-01

    In this work we present the results of the extensive molecular simulations of solute-solvent cavity and bridge functions. The mixtures of Lennard-Jones solvent with Lennard-Jones solute at infinite dilution are considered for different solute-solvent size ratios—up to 4:1. The Percus-Yevick and hypernetted chain closures deviate substantially from simulation results in the investigated temperature and density ranges. We also find that the behavior of the indirect and cavity correlation functions is non-monotonous within the hard-core region, but the latter can be successfully approximated by mean-field theory if the solute-solvent interaction energy is divided into repulsive and attractive contribution, according to Weeks-Chandler-Andersen theory. Furthermore, in spite of the non-monotonous behavior of logarithm of the cavity function and the indirect correlation function, their difference, i.e., the bridge function remains constant within the hard-core region. Such behavior of the bridge and indirect correlation functions at small distances and for small values of indirect correlation function is well known from the Duh-Haymet plots, where the non-unique relationship results in loops of the bridge function vs. indirect correlation function graphs. We show that the same pathological behavior appears also when distance is small and indirect correlation function is large. We further show that the unique functional behavior of the bridge function can be established when bridge is represented as a function of the renormalized, repulsive indirect correlation function

  1. Sexual Functioning and Behavior of Men with Body Dysmorphic Disorder Concerning Penis Size Compared with Men Anxious about Penis Size and with Controls: A Cohort Study

    OpenAIRE

    Veale, David; Miles, Sarah; Read, Julie; Troglia, Andrea; Wylie, Kevan; Muir, Gordon

    2015-01-01

    Introduction: Little is known about the sexual functioning and behavior of men anxious about the size of their penis and the means that they might use to try to alter the size of their penis. Aim: To compare sexual functioning and behavior in men with body dysmorphic disorder (BDD) concerning penis size and in men with small penis anxiety (SPA without BDD) and in a control group of men who do not have any concerns. Methods: An opportunistic sample of 90 men from the community were recru...

  2. The release of mineral matter and associated phosphorus as a function of the particle size coal

    Energy Technology Data Exchange (ETDEWEB)

    Claassens, V. [Sasol Technology Research & Development, Sasolburg (South Africa). Syngas & Coal Technologies

    2009-05-15

    The presence of phosphorus in carbon reductants is a major concern in the metallurgical industry. The behaviour of the phosphorus and mineral matter content (reported as ash) as a function of particle size was investigated. The primary aim of this study was to determine the reduction in phosphorus and mineral matter that occurred as the particle size decreased. A secondary aim was to determine how the phosphorus was distributed in the feed coal and to where it reported during floc-flotation. Results showed that the ash content decreased more rapidly than the phosphorus content as the mean particle size was reduced. It remains unclear why P-rejection is only half as effective as mineral matter rejection. Detailed liberation analysis of P-containing minerals is required to possibly explain this phenomenon.

  3. Balloon dilation of the esophago-gastric junction affects lower and upper esophageal sphincter function in achalasia.

    Science.gov (United States)

    Wauters, L; Van Oudenhove, L; Selleslagh, M; Vanuytsel, T; Boeckxstaens, G; Tack, J; Omari, T; Rommel, N

    2014-01-01

    Pneumatic dilation of the lower esophageal sphincter (LES) in achalasia has an unappreciated effect on upper esophageal sphincter (UES) function. We studied UES pressure patterns at baseline and alterations in UES parameters resulting from therapy. High-resolution manometry (HRM) tracings from 50 achalasia patients, seen at a tertiary center between January 2009 and July 2011, were reviewed. Manometric parameters studied were (i) LES: resting pressure (restP), 4-second integrated relaxation pressure (IRP4); (ii) UES: resting pressure (restP), minimal relaxation pressure (MRP), peak pressure (PP), relaxation interval (RI), intrabolus pressure (IBP), and deglutitive sphincter resistance (DSR). Mixed models analyses with LES and UES parameters as dependent variables and treatment stage as within-subject independent variable of interest were used. Correlations between treatment-induced changes in LES, UES, and esophageal body (EB) parameters were performed. Pre- and posttreatment HRM tracings were available from 50 patients (mean age 52.7 ± 18.6 years, 29 men). Upper esophageal sphincter parameters MRP (17.9 ± 1.2 vs 15.2 ± 0.9 mmHg; p = 0.02) and IBP (31.5 ± 1.5 vs 27.4 ± 1.2 mmHg; p = 0.009) were significantly reduced after initial balloon dilation and this effect was significant in type II achalasia (p = 0.002 and p = 0.0006). Peak pressure, RI, and DSR were not. The therapeutic effect on LES IRP4 correlated significantly with the change in UES MRP, statistically mediated by the change in EB deglutitive pressure (p = 0.004 and p = 0.0002). We present the first HRM study demonstrating that pneumatic dilation of the LES affects intraesophageal and UES pressures in patients with achalasia. © 2013 John Wiley & Sons Ltd.

  4. In Vivo Damage of the Head-Neck Junction in Hard-on-Hard Total Hip Replacements: Effect of Femoral Head Size, Metal Combination, and 12/14 Taper Design

    Directory of Open Access Journals (Sweden)

    Massimiliano Baleani

    2017-07-01

    Full Text Available Recently, concerns have been raised about the potential effect of head-neck junction damage products at the local and systemic levels. Factors that may affect this damage process have not been fully established yet. This study investigated the possible correlations among head-neck junction damage level, implant design, material combination, and patient characteristics. Head-neck junctions of 148 retrieved implants were analysed, including both ceramic-on-ceramic (N = 61 and metal-on-metal (N = 87 bearings. In all cases, the male taper was made of titanium alloy. Damage was evaluated using a four-point scoring system based on damage morphology and extension. Patient age at implantation, implantation time, damage risk factor, and serum ion concentration were considered as independent potential predicting variables. The damage risk factor summarises head-neck design characteristics and junction loading condition. Junction damage correlated with both implantation time and damage factor risk when the head was made of ceramic. A poor correlation was found when the head was made of cobalt alloy. The fretting-corrosion phenomenon seemed mainly mechanically regulated, at least when cobalt alloy components were not involved. When a component was made of cobalt alloy, the role of chemical phenomena increased, likely becoming, over implantation time, the damage driving phenomena of highly stressed junctions.

  5. Functional size of photosynthetic electron transport chain determined by radiation inactivation

    International Nuclear Information System (INIS)

    Pan, R.S.; Chen, L.F.; Wang, M.Y.; Tsal, M.Y.; Pan, R.L.; Hsu, B.D.

    1987-01-01

    Radiation inactivation technique was employed to determine the functional size of photosynthetic electron transport chain of spinach chloroplasts. The functional size for photosystem I+II(H 2 O to methylviologen) was 623 +/- 37 kilodaltons; for photosystem II (H 2 O to dimethylquinone/ferricyanide), 174 +/- 11 kilodaltons; and for photosystem I (reduced diaminodurene to methylviologen), 190 +/- 11 kilodaltons. The difference between 364 +/- 22 (the sum of 174 +/- 11 and 190 +/- 11) kilodaltons and 623 +/- 37 kilodaltons is partially explained to be due to the presence of two molecules of cytochrome b 6 /f complex of 280 kilodaltons. The molecular mass for other partial reactions of photosynthetic electron flow, also measured by radiation inactivation, is reported. The molecular mass obtained by this technique is compared with that determined by other conventional biochemical methods. A working hypothesis for the composition, stoichiometry, and organization of polypeptides for photosynthetic electron transport chain is proposed

  6. Size-dependent axisymmetric vibration of functionally graded circular plates in bifurcation/limit point instability

    Science.gov (United States)

    Ashoori, A. R.; Vanini, S. A. Sadough; Salari, E.

    2017-04-01

    In the present paper, vibration behavior of size-dependent functionally graded (FG) circular microplates subjected to thermal loading are carried out in pre/post-buckling of bifurcation/limit-load instability for the first time. Two kinds of frequently used thermal loading, i.e., uniform temperature rise and heat conduction across the thickness direction are considered. Thermo-mechanical material properties of FG plate are supposed to vary smoothly and continuously throughout the thickness based on power law model. Modified couple stress theory is exploited to describe the size dependency of microplate. The nonlinear governing equations of motion and associated boundary conditions are extracted through generalized form of Hamilton's principle and von-Karman geometric nonlinearity for the vibration analysis of circular FG plates including size effects. Ritz finite element method is then employed to construct the matrix representation of governing equations which are solved by two different strategies including Newton-Raphson scheme and cylindrical arc-length method. Moreover, in the following a parametric study is accompanied to examine the effects of the several parameters such as material length scale parameter, temperature distributions, type of buckling, thickness to radius ratio, boundary conditions and power law index on the dimensionless frequency of post-buckled/snapped size-dependent FG plates in detail. It is found that the material length scale parameter and thermal loading have a significant effect on vibration characteristics of size-dependent circular FG plates.

  7. An Echocardiographic Study of Left Ventricular Size and Cardiac Function in Adolescent Females with Anorexia Nervosa.

    Science.gov (United States)

    Escudero, Carolina A; Potts, James E; Lam, Pei-Yoong; De Souza, Astrid M; Mugford, Gerald J; Sandor, George G S

    2016-01-01

    This retrospective case-control study investigated cardiac dimensions and ventricular function in female adolescents with anorexia nervosa (AN) compared with controls. Echocardiographic measurements of left ventricular (LV) dimensions, LV mass index, left atrial size and cardiac index were made. Detailed measures of systolic and diastolic ventricular function were made including tissue Doppler imaging. Patients were stratified by body mass index ≤10th percentile (AN ≤ 10th) and >10th percentile (AN > 10th). Ninety-five AN patients and 58 controls were included. AN and AN ≤ 10th groups had reduced LV dimensions, LV mass index, left atrial size and cardiac index compared with controls. There were no differences between groups in measures of systolic function. Measures of diastolic tissue Doppler imaging were decreased in AN and AN ≤ 10th. No differences in echocardiographic measurements existed between controls and AN > 10th. Female adolescents with AN have preserved systolic function and abnormalities of diastolic ventricular function. AN ≤ 10th may be a higher risk group. Copyright © 2015 John Wiley & Sons, Ltd and Eating Disorders Association.

  8. Farm size, land yields, and the agricultural production function: an analysis for fifteen developing countries

    Energy Technology Data Exchange (ETDEWEB)

    Cornia, G A

    1985-04-01

    This paper analyzes the relationship between factor inputs, land yields, and labor productivity for farms of different size on the basis of FAO farm management data for 15 developing countries. For all but three countries a strong negative correlation is found between farm size on the one side, and factor inputs and yields per hectare on the other. The fitting of unconstrained production functions to the above data suggests that in only few cases can the decline in yields for increasing farm size be attributed to decreasing returns to scale. The higher yields observed in small farms are mainly to be ascribed to higher factor inputs and to a more intensive use of land. Therefore, where conspicuous labor surpluses exist, the superiority of small farming provides solid arguments in favor of land redistribution. Such an agrarian reform would determine higher output, higher labor absorption and a more equitable income distribution, thus contributing in a decisive manner to the alleviation of rural poverty. The paper also provides estimates of cross-sectional production functions for the 15 countries analyzed. Empirical relations are found between the output elasticities of land, labor, and intermediate inputs and physical indicators of their scarcity. The paper concludes by proposing a simple method for deriving a long-term production function for agriculture. 23 references, 3 figures, 6 tables.

  9. Valley dependent transport in graphene L junction

    Science.gov (United States)

    Chan, K. S.

    2018-05-01

    We studied the valley dependent transport in graphene L junctions connecting an armchair lead and a zigzag lead. The junction can be used in valleytronic devices and circuits. Electrons injected from the armchair lead into the junction is not valley polarized, but they can become valley polarized in the zigzag lead. There are Fermi energies, where the current in the zigzag lead is highly valley polarized and the junction is an efficient generator of valley polarized current. The features of the valley polarized current depend sensitively on the widths of the two leads, as well as the number of dimers in the armchair lead, because this number has a sensitive effect on the band structure of the armchair lead. When an external potential is applied to the junction, the energy range with high valley polarization is enlarged enhancing its function as a generator of highly valley polarized current. The scaling behavior found in other graphene devices is also found in L junctions, which means that the results presented here can be extended to junctions with larger dimensions after appropriate scaling of the energy.

  10. Metallic behavior and negative differential resistance properties of (InAs)n (n = 2 − 4) molecule cluster junctions via a combined non–equilibrium Green's function and density functional theory study

    International Nuclear Information System (INIS)

    Wang, Qi; Li, Rong; Xu, Yuanlan; Zhang, Jianbing; Miao, Xiangshui; Zhang, Daoli

    2014-01-01

    In this present work, the geometric structures and electronic transport properties of (InAs) n (n = 2, 3, 4) molecule cluster junctions are comparatively investigated using NEGF combined with DFT. Results indicate that all (InAs) n molecule cluster junctions present metallic behavior at the low applied biases ([−2V, 2V]), while NDR appears at a certain high bias range. Our calculation shows that the current of (InAs) 4 molecule cluster–based junction is almost the largest at any bias. The mechanisms of the current–voltage characteristics of all the three molecule cluster junctions are proposed.

  11. Modeling fractal structure of city-size distributions using correlation functions.

    Science.gov (United States)

    Chen, Yanguang

    2011-01-01

    Zipf's law is one the most conspicuous empirical facts for cities, however, there is no convincing explanation for the scaling relation between rank and size and its scaling exponent. Using the idea from general fractals and scaling, I propose a dual competition hypothesis of city development to explain the value intervals and the special value, 1, of the power exponent. Zipf's law and Pareto's law can be mathematically transformed into one another, but represent different processes of urban evolution, respectively. Based on the Pareto distribution, a frequency correlation function can be constructed. By scaling analysis and multifractals spectrum, the parameter interval of Pareto exponent is derived as (0.5, 1]; Based on the Zipf distribution, a size correlation function can be built, and it is opposite to the first one. By the second correlation function and multifractals notion, the Pareto exponent interval is derived as [1, 2). Thus the process of urban evolution falls into two effects: one is the Pareto effect indicating city number increase (external complexity), and the other the Zipf effect indicating city size growth (internal complexity). Because of struggle of the two effects, the scaling exponent varies from 0.5 to 2; but if the two effects reach equilibrium with each other, the scaling exponent approaches 1. A series of mathematical experiments on hierarchical correlation are employed to verify the models and a conclusion can be drawn that if cities in a given region follow Zipf's law, the frequency and size correlations will follow the scaling law. This theory can be generalized to interpret the inverse power-law distributions in various fields of physical and social sciences.

  12. CRITICAL FACTORS IN OUTSOURCING OF ACCOUNTING FUNCTIONS IN MALAYSIAN SMALL MEDIUM-SIZED ENTERPRISES (SMEs

    Directory of Open Access Journals (Sweden)

    Magiswary Dorasamy

    2010-01-01

    Full Text Available The challenges that business face in sustaining competitive advantage in the corporate world have become a major concern. Businesses are adopting cutting-edge technologies and best practices to cope with rapid, global changes. Various business functions are being reengineered for this purpose. Accounting functions play an important role in helping businesses to maintain competitive advantage. However, some small and medium-sized enterprises (SMEs face problems handling fundamental accounting functions. This is predominantly because of their lack of expertise; accounting functions require not only knowledge of generally accepted accounting rules or tax regulations but also the expertise needed to apply the rules in a given business environment (Everaert, Sarens and Rommel, 2006. This paper offers some insight on the outsourcing of accounting functions as there is paucity of data in this area in the context of Malaysia. Essentially, it presents empirical evidence regarding Malaysian SMEs' accounting outsourcing practices. A survey of SMEs was conducted to identify the overall outsourcing landscape as it relates to accounting and third-party organisations. The factors that contribute to the decision to outsource accounting functions are analysed. The study reveals a significant relationship between outsourcing accounting functions and two contributing factors, risks and operation management.

  13. Ultrasonographic evaluation of Hashimoto's thyroiditis: Comparison of size and echo change with thyroid function

    International Nuclear Information System (INIS)

    Lee, Kang Rae; Cho, Jae Hyun; Kim, Yun Jeong; Kim, Hyun Man; Park, Rae Woong; Suh, Jung Ho; Kang, Byung Chul

    1999-01-01

    To demonstrate sonographic features of Hashimoto's thyroiditis according to the thyroid function. We reviewed 54 thyroid ultrasonographic examinations of untreated Hashimoto's thyroiditis. We reviewed thyroid ultrasonographic examinations and focused on the presence of ill-defined low echoic lesions and glandular enlargement. We performed another thyroid ultrasonographic examination of 14 healthy volunteers, in order to obtain normal size of thyroid gland. Comparison was made between these morphologic characteristics and functional stage of the disease. The mean diameter of thyroid gland was 2.16 ± 0.43 cm in patients with Hashimoto's thyroiditis, and 1.41 ± 0.42 cm in normal control group of the thyroid gland. There was no statistically significant relationship between thyroid function and size. There was morphologic abnormalities in 46 patients (85%). Among them, 7 patients revealed diffuse low echogenicity in the entire thyroid gland, 32 patients showed peripherally located, ill-defined focal hypoechoic lesion, and 7 patients showed solitary or multiple. well-defined nodular lesions. Decreased echogenicity of the thyroid gland was related to hypothyroid status. Hashimoto's thyroiditis has specific morphologue characteristics in ultrasonographic features, which are well correlated with thyroid function.

  14. Functional size of vacuolar H+ pumps: Estimates from radiation inactivation studies

    International Nuclear Information System (INIS)

    Sarafian, V.; Poole, R.J.

    1991-01-01

    The PPase and the ATPase from red beet (Beta vulgaris) vacuolar membranes were subjected to radiation inactivation by a 60 Co source in both the native tonoplast and detergent-solubilized states, in order to determine their target molecular sizes. Analysis of the residual phosphohydrolytic and proton transport activities, after exposure to varying doses of radiation, yielded exponential relationships between the activities and radiation doses. The deduced target molecular sizes for PPase activity in native and solubilized membranes were 125kD and 259kD respectively and 327kD for H + -transport. This suggests that the minimum number of subunits of 67kD for PPi hydrolysis is two in the native state and four after Triton X-100 solubilization. At least four subunits would be required for H + -translocation. Analysis of the ATPase inactivation patterns revealed target sizes of 384kD and 495kD for ATP hydrolysis in native and solubilized tonoplast respectively and 430kD for H + -transport. These results suggest that the minimum size for hydrolytic or transport functions is relatively constant for the ATPase

  15. Macroscopic quantum tunneling in Josephson tunnel junctions and Coulomb blockade in single small tunnel junctions

    International Nuclear Information System (INIS)

    Cleland, A.N.

    1991-01-01

    Experiments investigated the process of macroscopic quantum tunneling in a moderately-damped, resistively shunted, Josephson junction are described, followed by a discussion of experiments performed on very-small-capacitance normal-metal tunnel junctions. The experiments on the resistively-shunted Josephson junction were designed to investigate a quantum process, that of the tunneling of the Josephson-phase variable under a potential barrier, in a system in which dissipation plays a major role in the dynamics of motion. All the parameters of the junction were measured using the classical phenomena of thermal activation and resonant activation. Theoretical predictions are compared with the experimental results, showing good agreement with no adjustable parameters. The experiments on small-capacitance tunnel junctions extend the measurements on the large-area Josephson junctions from the region in which the phase variable has a fairly well-defined value, i.e. its wave function has a narrow width, to the region where its value is almost completely unknown. The charge on the junction becomes well-defined and is predicted to quantize the current through the junction, giving rise to the Coulomb blockade at low bias

  16. Sexual Functioning and Behavior of Men with Body Dysmorphic Disorder Concerning Penis Size Compared with Men Anxious about Penis Size and with Controls: A Cohort Study

    Science.gov (United States)

    Veale, David; Miles, Sarah; Read, Julie; Troglia, Andrea; Wylie, Kevan; Muir, Gordon

    2015-01-01

    Introduction Little is known about the sexual functioning and behavior of men anxious about the size of their penis and the means that they might use to try to alter the size of their penis. Aim To compare sexual functioning and behavior in men with body dysmorphic disorder (BDD) concerning penis size and in men with small penis anxiety (SPA without BDD) and in a control group of men who do not have any concerns. Methods An opportunistic sample of 90 men from the community were recruited and divided into three groups: BDD (n = 26); SPA (n = 31) and controls (n = 33). Main Outcome Measures The Index of Erectile Function (IEF), sexual identity and history; and interventions to alter the size of their penis. Results Men with BDD compared with controls had reduced erectile dysfunction, orgasmic function, intercourse satisfaction and overall satisfaction on the IEF. Men with SPA compared with controls had reduced intercourse satisfaction. There were no differences in sexual desire, the frequency of intercourse or masturbation across any of the three groups. Men with BDD and SPA were more likely than the controls to attempt to alter the shape or size of their penis (for example jelqing, vacuum pumps or stretching devices) with poor reported success. Conclusion Men with BDD are more likely to have erectile dysfunction and less satisfaction with intercourse than controls but maintain their libido. Further research is required to develop and evaluate a psychological intervention for such men with adequate outcome measures. PMID:26468378

  17. Sexual Functioning and Behavior of Men with Body Dysmorphic Disorder Concerning Penis Size Compared with Men Anxious about Penis Size and with Controls: A Cohort Study.

    Science.gov (United States)

    Veale, David; Miles, Sarah; Read, Julie; Troglia, Andrea; Wylie, Kevan; Muir, Gordon

    2015-09-01

    Little is known about the sexual functioning and behavior of men anxious about the size of their penis and the means that they might use to try to alter the size of their penis. To compare sexual functioning and behavior in men with body dysmorphic disorder (BDD) concerning penis size and in men with small penis anxiety (SPA without BDD) and in a control group of men who do not have any concerns. An opportunistic sample of 90 men from the community were recruited and divided into three groups: BDD (n = 26); SPA (n = 31) and controls (n = 33). The Index of Erectile Function (IEF), sexual identity and history; and interventions to alter the size of their penis. Men with BDD compared with controls had reduced erectile dysfunction, orgasmic function, intercourse satisfaction and overall satisfaction on the IEF. Men with SPA compared with controls had reduced intercourse satisfaction. There were no differences in sexual desire, the frequency of intercourse or masturbation across any of the three groups. Men with BDD and SPA were more likely than the controls to attempt to alter the shape or size of their penis (for example jelqing, vacuum pumps or stretching devices) with poor reported success. Men with BDD are more likely to have erectile dysfunction and less satisfaction with intercourse than controls but maintain their libido. Further research is required to develop and evaluate a psychological intervention for such men with adequate outcome measures.

  18. Prognostic value of left atrial size and function in adults with tetralogy of Fallot.

    Science.gov (United States)

    Baggen, Vivan J M; Schut, Anne-Rose W; Cuypers, Judith A A E; Witsenburg, Maarten; Boersma, Eric; van den Bosch, Annemien E; Roos-Hesselink, Jolien W

    2017-06-01

    Left atrial (LA) size predicts cardiovascular outcome in chronic heart failure. Its prognostic value in adults with repaired tetralogy of Fallot (ToF) is unknown. This study therefore investigated the association of LA size and function with cardiovascular events in adults with ToF. Clinically stable adults with ToF who visited the outpatient clinic between 2011 and 2013 underwent echocardiography and were prospectively followed for the occurrence of death, heart failure, hospitalizations, arrhythmia, thromboembolic events, and re-interventions. LA maximal, minimal and pre-A wave volume, area and length were measured on the apical four-chamber view. Total, passive and active emptying fractions were calculated. In total, 134 patients were included (median age 35 [IQR 29-45] years, 65% male, 91% NYHA I). Median follow-up was 40 [IQR 32-47] months. Patients with a dilated LA (≥34mL/m 2 , 43%) were at higher risk of cardiovascular events (n=33, adjusted HR 2.48 [1.09-5.62], P=0.030). Analysis of LA volumes as continuous variables yielded similar conclusions. In addition, LA length (adjusted HR 2.49 [1.51-4.09], P<0.001), total emptying fraction (adjusted HR 0.96 [0.93-0.99], P=0.008), and active emptying fraction (adjusted HR 0.92 [0.87-0.96], P=0.001) were significantly associated with cardiovascular events. Standardized HRs indicated that LA length was the strongest prognostic marker. In addition, none of the patients with a normally sized LA died or developed heart failure. LA size and function can provide relevant prognostic information in clinically stable adults with repaired ToF. Especially LA length may be a valuable additional tool in the risk stratification of these patients. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. SIZE AND FIELD OF ACTIVITY INFLUENCE ON WEB SITES FUNCTIONALITY FOR ROMANIAN COMPANIES

    Directory of Open Access Journals (Sweden)

    Tarca Ioan

    2008-05-01

    Full Text Available The internet became an important part of the company’s informational system. In order to take advantage on the Internet’s interactive nature, a lot of companies have created their own websites. Companies use the website for numerous applications: to promote themselves, online shopping, and communication with targeted clients. This study reveals the fact that the company’s size and field of activity have influence on website’s functionality and interactivity. Small companies use the website to successfully compete corporations which do not have yet necessary stimulants to fully exploit the internet capacities.

  20. Functional polythiophene nanoparticles: Size-controlled electropolymerization and ion selective response

    DEFF Research Database (Denmark)

    Si, P.C.; Chi, Qijin; Li, Z.S.

    2007-01-01

    polymerization to form polymer nanoparticles or clusters by which the size of the polymer nanoparticles can further be controlled electrochemically. The electropolymerization was monitored in situ by scanning tunneling microscopy to unravel the dynamics of the process and possible mechanisms. These are further......We have synthesized a thiophene derivative, (4-benzeno-15-crown-5 ether)-thiophene-3-methylene-amine (BTA), which was used as a monomer for electrochemical polymerization on metallic surfaces to prepare functional polymer films. Self-assembly of BTA monomers on Au(111) surfaces promotes ordered...

  1. Molecular Diffusion through Cyanobacterial Septal Junctions.

    Science.gov (United States)

    Nieves-Morión, Mercedes; Mullineaux, Conrad W; Flores, Enrique

    2017-01-03

    Heterocyst-forming cyanobacteria grow as filaments in which intercellular molecular exchange takes place. During the differentiation of N 2 -fixing heterocysts, regulators are transferred between cells. In the diazotrophic filament, vegetative cells that fix CO 2 through oxygenic photosynthesis provide the heterocysts with reduced carbon and heterocysts provide the vegetative cells with fixed nitrogen. Intercellular molecular transfer has been traced with fluorescent markers, including calcein, 5-carboxyfluorescein, and the sucrose analogue esculin, which are observed to move down their concentration gradient. In this work, we used fluorescence recovery after photobleaching (FRAP) assays in the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 to measure the temperature dependence of intercellular transfer of fluorescent markers. We find that the transfer rate constants are directly proportional to the absolute temperature. This indicates that the "septal junctions" (formerly known as "microplasmodesmata") linking the cells in the filament allow molecular exchange by simple diffusion, without any activated intermediate state. This constitutes a novel mechanism for molecular transfer across the bacterial cytoplasmic membrane, in addition to previously characterized mechanisms for active transport and facilitated diffusion. Cyanobacterial septal junctions are functionally analogous to the gap junctions of metazoans. Although bacteria are frequently considered just as unicellular organisms, there are bacteria that behave as true multicellular organisms. The heterocyst-forming cyanobacteria grow as filaments in which cells communicate. Intercellular molecular exchange is thought to be mediated by septal junctions. Here, we show that intercellular transfer of fluorescent markers in the cyanobacterial filament has the physical properties of simple diffusion. Thus, cyanobacterial septal junctions are functionally analogous to metazoan gap junctions

  2. See food diet? Cultural differences in estimating fullness and intake as a function of plate size.

    Science.gov (United States)

    Peng, Mei; Adam, Sarah; Hautus, Michael J; Shin, Myoungju; Duizer, Lisa M; Yan, Huiquan

    2017-10-01

    Previous research has suggested that manipulations of plate size can have a direct impact on perception of food intake, measured by estimated fullness and intake. The present study, involving 570 individuals across Canada, China, Korea, and New Zealand, is the first empirical study to investigate cultural influences on perception of food portion as a function of plate size. The respondents viewed photographs of ten culturally diverse dishes presented on large (27 cm) and small (23 cm) plates, and then rated their estimated usual intake and expected fullness after consuming the dish, using 100-point visual analog scales. The data were analysed with a mixed-model ANCOVA controlling for individual BMI, liking and familiarity of the presented food. The results showed clear cultural differences: (1) manipulations of the plate size had no effect on the expected fullness or the estimated intake of the Chinese and Korean respondents, as opposed to significant effects in Canadians and New Zealanders (p Asian respondents. Overall, these findings, from a cultural perspective, support the notion that estimation of fullness and intake are learned through dining experiences, and highlight the importance of considering eating environments and contexts when assessing individual behaviours relating to food intake. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Primary Tunnel Junction Thermometry

    International Nuclear Information System (INIS)

    Pekola, Jukka P.; Holmqvist, Tommy; Meschke, Matthias

    2008-01-01

    We describe the concept and experimental demonstration of primary thermometry based on a four-probe measurement of a single tunnel junction embedded within four arrays of junctions. We show that in this configuration random sample specific and environment-related errors can be avoided. This method relates temperature directly to Boltzmann constant, which will form the basis of the definition of temperature and realization of official temperature scales in the future

  4. Influence of secular trends and sample size on reference equations for lung function tests.

    Science.gov (United States)

    Quanjer, P H; Stocks, J; Cole, T J; Hall, G L; Stanojevic, S

    2011-03-01

    The aim of our study was to determine the contribution of secular trends and sample size to lung function reference equations, and establish the number of local subjects required to validate published reference values. 30 spirometry datasets collected between 1978 and 2009 provided data on healthy, white subjects: 19,291 males and 23,741 females aged 2.5-95 yrs. The best fit for forced expiratory volume in 1 s (FEV(1)), forced vital capacity (FVC) and FEV(1)/FVC as functions of age, height and sex were derived from the entire dataset using GAMLSS. Mean z-scores were calculated for individual datasets to determine inter-centre differences. This was repeated by subdividing one large dataset (3,683 males and 4,759 females) into 36 smaller subsets (comprising 18-227 individuals) to preclude differences due to population/technique. No secular trends were observed and differences between datasets comprising >1,000 subjects were small (maximum difference in FEV(1) and FVC from overall mean: 0.30- -0.22 z-scores). Subdividing one large dataset into smaller subsets reproduced the above sample size-related differences and revealed that at least 150 males and 150 females would be necessary to validate reference values to avoid spurious differences due to sampling error. Use of local controls to validate reference equations will rarely be practical due to the numbers required. Reference equations derived from large or collated datasets are recommended.

  5. Joint diseases: from connexins to gap junctions.

    Science.gov (United States)

    Donahue, Henry J; Qu, Roy W; Genetos, Damian C

    2017-12-19

    Connexons form the basis of hemichannels and gap junctions. They are composed of six tetraspan proteins called connexins. Connexons can function as individual hemichannels, releasing cytosolic factors (such as ATP) into the pericellular environment. Alternatively, two hemichannel connexons from neighbouring cells can come together to form gap junctions, membrane-spanning channels that facilitate cell-cell communication by enabling signalling molecules of approximately 1 kDa to pass from one cell to an adjacent cell. Connexins are expressed in joint tissues including bone, cartilage, skeletal muscle and the synovium. Indicative of their importance as gap junction components, connexins are also known as gap junction proteins, but individual connexin proteins are gaining recognition for their channel-independent roles, which include scaffolding and signalling functions. Considerable evidence indicates that connexons contribute to the function of bone and muscle, but less is known about the function of connexons in other joint tissues. However, the implication that connexins and gap junctional channels might be involved in joint disease, including age-related bone loss, osteoarthritis and rheumatoid arthritis, emphasizes the need for further research into these areas and highlights the therapeutic potential of connexins.

  6. Corrosion resistant surface for vanadium nitride and hafnium nitride layers as function of grain size

    Science.gov (United States)

    Escobar, C. A.; Caicedo, J. C.; Aperador, W.

    2014-01-01

    In this research it was studied vanadium nitride (VN) and hafnium nitride (HfN) film, which were deposited onto silicon (Si (100)) and AISI 4140 steel substrates via r.f. magnetron sputtering technique in Ar/N2 atmosphere with purity at 99.99% for both V and Hf metallic targets. Both films were approximately 1.2±0.1 μm thick. The crystallography structures that were evaluated via X-ray diffraction analysis (XRD) showed preferential orientations in the Bragg planes VN (200) and HfN (111). The chemical compositions for both films were characterized by EDX. Atomic Force Microscopy (AFM) was used to study the morphology; the results reveal grain sizes of 78±2 nm for VN and 58±2 nm for HfN and roughness values of 4.2±0.1 nm for VN and 1.5±0.1 nm for HfN films. The electrochemical performance in VN and HfN films deposited onto steel 4140 were studied by Tafel polarization curves and impedance spectroscopy methods (EIS) under contact with sodium chloride at 3.5 wt% solution, therefore, it was found that the corrosion rate decreased about 95% in VN and 99% for HfN films in relation to uncoated 4140 steel, thus demonstrating, the protecting effect of VN and HfN films under a corrosive environment as function of morphological characteristics (grain size). VN(grain size)=78±2.0 nm, VN(roughness)=4.2±0.1 nm, VN(corrosion rate)=40.87 μmy. HfN(grain size)=58±2.0 nm, HfN(roughness)=1.5±0.1 nm, HfN(corrosion rate)=0.205 μmy. It was possible to analyze that films with larger grain size, can be observed smaller grain boundary thus generating a higher corrosion rate, therefore, in this work it was found that the HfN layer has better corrosion resistance (low corrosion rate) in relation to VN film which presents a larger grain size, indicating that the low grain boundary in (VN films) does not restrict movement of the Cl- ion and in this way the corrosion rate increases dramatically.

  7. Density fractions versus size separates: does physical fractionation isolate functional soil compartments?

    Directory of Open Access Journals (Sweden)

    C. Moni

    2012-12-01

    Full Text Available Physical fractionation is a widely used methodology to study soil organic matter (SOM dynamics, but concerns have been raised that the available fractionation methods do not well describe functional SOM pools. In this study we explore whether physical fractionation techniques isolate soil compartments in a meaningful and functionally relevant way for the investigation of litter-derived nitrogen dynamics at the decadal timescale. We do so by performing aggregate density fractionation (ADF and particle size-density fractionation (PSDF on mineral soil samples from two European beech forests a decade after application of 15N labelled litter.

    Both density and size-based fractionation methods suggested that litter-derived nitrogen became increasingly associated with the mineral phase as decomposition progressed, within aggregates and onto mineral surfaces. However, scientists investigating specific aspects of litter-derived nitrogen dynamics are pointed towards ADF when adsorption and aggregation processes are of interest, whereas PSDF is the superior tool to research the fate of particulate organic matter (POM.

    Some methodological caveats were observed mainly for the PSDF procedure, the most important one being that fine fractions isolated after sonication can not be linked to any defined decomposition pathway or protective mechanism. This also implies that historical assumptions about the "adsorbed" state of carbon associated with fine fractions need to be re-evaluated. Finally, this work demonstrates that establishing a comprehensive picture of whole soil OM dynamics requires a combination of both methodologies and we offer a suggestion for an efficient combination of the density and size-based approaches.

  8. Ouabain stimulates a Na+/K+-ATPase-mediated SFK-activated signalling pathway that regulates tight junction function in the mouse blastocyst.

    Directory of Open Access Journals (Sweden)

    Holly Giannatselis

    Full Text Available The Na(+/K(+-ATPase plays a pivotal role during preimplantation development; it establishes a trans-epithelial ionic gradient that facilitates the formation of the fluid-filled blastocyst cavity, crucial for implantation and successful pregnancy. The Na(+/K(+-ATPase is also implicated in regulating tight junctions and cardiotonic steroid (CTS-induced signal transduction via SRC. We investigated the expression of SRC family kinase (SFK members, Src and Yes, during preimplantation development and determined whether SFK activity is required for blastocyst formation. Embryos were collected following super-ovulation of CD1 or MF1 female mice. RT-PCR was used to detect SFK mRNAs encoding Src and Yes throughout preimplantation development. SRC and YES protein were localized throughout preimplantation development. Treatment of mouse morulae with the SFK inhibitors PP2 and SU6656 for 18 hours resulted in a reversible blockade of progression to the blastocyst stage. Blastocysts treated with 10(-3 M ouabain for 2 or 10 minutes and immediately immunostained for phosphorylation at SRC tyr418 displayed reduced phosphorylation while in contrast blastocysts treated with 10(-4 M displayed increased tyr418 fluorescence. SFK inhibition increased and SFK activation reduced trophectoderm tight junction permeability in blastocysts. The results demonstrate that SFKs are expressed during preimplantation development and that SFK activity is required for blastocyst formation and is an important mediator of trophectoderm tight junction permeability.

  9. Electroplated Ni on the PN Junction Semiconductor

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Joo; Uhm, Young Rang; Son, Kwang Jae; Kim, Jong Bum; Choi, Sang Moo; Park, Jong Han; Hong, Jintae [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    Nickel (Ni) electroplating was implemented by using a metal Ni powder in order to establish a Ni-63 plating condition on the PN junction semiconductor needed for production of betavoltaic battery. PN junction semiconductors with a Ni seed layer of 500 and 1000 A were coated with Ni at current density from 10 to 50 mA cm{sup 2}. The surface roughness and average grain size of Ni deposits were investigated by XRD and SEM techniques. The roughness of Ni deposit was increased as the current density was increased, and decreased as the thickness of Ni seed layer was increased.

  10. Electroplated Ni on the PN Junction Semiconductor

    International Nuclear Information System (INIS)

    Kim, Jin Joo; Uhm, Young Rang; Son, Kwang Jae; Kim, Jong Bum; Choi, Sang Moo; Park, Jong Han; Hong, Jintae

    2015-01-01

    Nickel (Ni) electroplating was implemented by using a metal Ni powder in order to establish a Ni-63 plating condition on the PN junction semiconductor needed for production of betavoltaic battery. PN junction semiconductors with a Ni seed layer of 500 and 1000 A were coated with Ni at current density from 10 to 50 mA cm 2 . The surface roughness and average grain size of Ni deposits were investigated by XRD and SEM techniques. The roughness of Ni deposit was increased as the current density was increased, and decreased as the thickness of Ni seed layer was increased

  11. Statistical analysis of the phytocoenose homogeneity. IV. Species number and mean biomass value as functions of the area size

    Directory of Open Access Journals (Sweden)

    Anna J. Kwiatkowska

    2014-01-01

    Full Text Available Homogeneity of the Leocobryo-Pineturn phytocoenose was assessed on the grounds of the effect of area size on the species number and mean biomass value. It was confirmed that: I species number was a logarithmic function of the area size; 2 relation of individual species biomass to the area size was, as a rule, other than rectilinear, 3 the size of phytocoenose floristicly representative area differed from that determined with respect to the standing biomass and 4 phytocoenose homogeneity is related to the scale defined by the size of representative area.

  12. Methotrexate carried in lipid core nanoparticles reduces myocardial infarction size and improves cardiac function in rats

    Directory of Open Access Journals (Sweden)

    Maranhão RC

    2017-05-01

    Full Text Available Raul C Maranhão,1,2 Maria C Guido,1 Aline D de Lima,1 Elaine R Tavares,1 Alyne F Marques,1 Marcelo D Tavares de Melo,3 Jose C Nicolau,3 Vera MC Salemi,3 Roberto Kalil-Filho3 1Laboratory of Metabolism and Lipids, 2Faculty of Pharmaceutical Sciences, 3Heart Failure Unit, Clinical Cardiology Division, Heart Institute (InCor, Medical School Hospital, University of São Paulo, São Paulo, Brazil Purpose: Acute myocardial infarction (MI is accompanied by myocardial inflammation, fibrosis, and ventricular remodeling that, when excessive or not properly regulated, may lead to heart failure. Previously, lipid core nanoparticles (LDE used as carriers of the anti-inflammatory drug methotrexate (MTX produced an 80-fold increase in the cell uptake of MTX. LDE-MTX treatment reduced vessel inflammation and atheromatous lesions induced in rabbits by cholesterol feeding. The aim of the study was to investigate the effects of LDE-MTX on rats with MI, compared with commercial MTX treatment.Materials and methods: Thirty-eight Wistar rats underwent left coronary artery ligation and were treated with LDE-MTX, or with MTX (1 mg/kg intraperitoneally, once/week, starting 24 hours after surgery or with LDE without drug (MI-controls. A sham-surgery group (n=12 was also included. Echocardiography was performed 24 hours and 6 weeks after surgery. The animals were euthanized and their hearts were analyzed for morphometry, protein expression, and confocal microscopy.Results: LDE-MTX treatment achieved a 40% improvement in left ventricular (LV systolic function and reduced cardiac dilation and LV mass, as shown by echocardiography. LDE-MTX reduced the infarction size, myocyte hypertrophy and necrosis, number of inflammatory cells, and myocardial fibrosis, as shown by morphometric analysis. LDE-MTX increased antioxidant enzymes; decreased apoptosis, macrophages, reactive oxygen species production; and tissue hypoxia in non-infarcted myocardium. LDE-MTX increased adenosine

  13. Preparation of large-area molecular junctions with metallic conducting Langmuir–Blodgett films

    Energy Technology Data Exchange (ETDEWEB)

    Mochizuki, Kengo [Division of Marine Technology, Tokyo University of Marine Science and Technology, 2-1-6 Etchujima Koto-ku, Tokyo 135-8533 (Japan); Ohnuki, Hitoshi, E-mail: ohnuki@kaiyodai.ac.jp [Division of Marine Technology, Tokyo University of Marine Science and Technology, 2-1-6 Etchujima Koto-ku, Tokyo 135-8533 (Japan); Shimizu, Daisuke [Division of Marine Technology, Tokyo University of Marine Science and Technology, 2-1-6 Etchujima Koto-ku, Tokyo 135-8533 (Japan); Imakubo, Tatsuro [Department of Materials and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188 (Japan); Tsuya, Daiju [National Institute for Materials Science,1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Izumi, Mitsuru [Division of Marine Technology, Tokyo University of Marine Science and Technology, 2-1-6 Etchujima Koto-ku, Tokyo 135-8533 (Japan)

    2014-03-03

    Metallic conducting Langmuir–Blodgett (LB) films were used as soft electrodes to fabricate molecular junctions with self-assembled monolayers (SAMs) of alkanethiols (CH{sub 3}(CH{sub 2}){sub n−1}SH) on an Au surface. Alkanethiols can form highly ordered, stable dielectric SAMs on metal surfaces over large areas. However, it is difficult to establish electrical contacts on such SAMs, which has limited their application. In this work, we used metallic conducting LB films composed of bis(ethylenedioxy)tetrathiafulvalene and stearic acid as a soft electrode onto alkanethiol SAMs (C{sub n}-SAM, n = 12, 14, 16, 18) to prepare Au/SAM/metal junctions of relatively large size (∼ 15.6 × 10{sup 3} μm{sup 2}). The current density–voltage (J–V) characteristics across the junctions exhibited rectifying behavior with a ratio R of ∼ 5 (R = |J(V)|/|J(− V)| at ± 1 V). The lower transfer rate corresponding to the electron transport from Au to the LB films exhibited nonlinear J–V characteristics, while the higher transfer rate of electrons from the LB film to Au showed linear J–V characteristics. Kelvin probe force microscopy revealed that the work function of the metallic LB films was smaller than that of Au. The observed rectification behavior is probably caused by different electron transport mechanisms between the two current directions. - Highlights: • Metallic Langmuir–Blodgett (LB) films were used as soft electrodes. • Molecular junctions of metal–alkanethiol–LB films were fabricated. • The current–voltage curve across the junctions exhibited rectifying behavior. • This is the first observation for alkanethiol monolayer junctions. • The work function difference between the electrodes induces the rectification.

  14. Nest Digging by Leaf-Cutting Ants: Effect of Group Size and Functional Structures

    Directory of Open Access Journals (Sweden)

    Roberto da Silva Camargo

    2012-01-01

    Full Text Available Leaf-cutting ant workers dig underground chambers, for housing their symbiotic fungus, interconnected by a vast quantity of tunnels whose function is to permit the entrance of food (leaves, gaseous exchanges, and movement of workers, offspring, and the queen. Digging is a task executed by a group of workers, but little is known about the group effect and group-constructed functional structures. Thus, we analyzed the structures formed by worker groups (5, 10, 20, and 40 individuals of the leaf-cutting ant, Atta sexdens rubropilosa, for 2 days of excavation. The digging arena was the same for the 4 groups, with each group corresponding to a different density. Our results verified a pattern of tunneling by the workers, but no chamber was constructed. The group effect is well known, since the 40-worker group dug significantly more than the groups of 5, 10, and 20. These groups did not differ statistically from each other. Analysis of load/worker verified that workers of the smallest group carried the greatest load. Our paper demonstrates the group effect on the digging of nests, namely, that excavation is proportional to group size, but without emergence of a functional structure such as a chamber.

  15. Allee’s dynamics and bifurcation structures in von Bertalanffy’s population size functions

    Science.gov (United States)

    Leonel Rocha, J.; Taha, Abdel-Kaddous; Fournier-Prunaret, D.

    2018-03-01

    The interest and the relevance of the study of the population dynamics and the extinction phenomenon are our main motivation to investigate the induction of Allee Effect in von Bertalanffy’s population size functions. The adjustment or correction factor of rational type introduced allows us to analyze simultaneously strong and weak Allee’s functions and functions with no Allee effect, whose classification is dependent on the stability of the fixed point x = 0. This classification is founded on the concepts of strong and weak Allee’s effects to the population growth rates associated. The transition from strong Allee effect to no Allee effect, passing through the weak Allee effect, is verified with the evolution of the rarefaction critical density or Allee’s limit. The existence of cusp points on a fold bifurcation curve is related to this phenomenon of transition on Allee’s dynamics. Moreover, the “foliated” structure of the parameter plane considered is also explained, with respect to the evolution of the Allee limit. The bifurcation analysis is based on the configurations of fold and flip bifurcation curves. The chaotic semistability and the nonadmissibility bifurcation curves are proposed to this family of 1D maps, which allow us to define and characterize the corresponding Allee effect region.

  16. Colony size measurement of the yeast gene deletion strains for functional genomics

    Directory of Open Access Journals (Sweden)

    Mir-Rashed Nadereh

    2007-04-01

    Full Text Available Abstract Background Numerous functional genomics approaches have been developed to study the model organism yeast, Saccharomyces cerevisiae, with the aim of systematically understanding the biology of the cell. Some of these techniques are based on yeast growth differences under different conditions, such as those generated by gene mutations, chemicals or both. Manual inspection of the yeast colonies that are grown under different conditions is often used as a method to detect such growth differences. Results Here, we developed a computerized image analysis system called Growth Detector (GD, to automatically acquire quantitative and comparative information for yeast colony growth. GD offers great convenience and accuracy over the currently used manual growth measurement method. It distinguishes true yeast colonies in a digital image and provides an accurate coordinate oriented map of the colony areas. Some post-processing calculations are also conducted. Using GD, we successfully detected a genetic linkage between the molecular activity of the plant-derived antifungal compound berberine and gene expression components, among other cellular processes. A novel association for the yeast mek1 gene with DNA damage repair was also identified by GD and confirmed by a plasmid repair assay. The results demonstrate the usefulness of GD for yeast functional genomics research. Conclusion GD offers significant improvement over the manual inspection method to detect relative yeast colony size differences. The speed and accuracy associated with GD makes it an ideal choice for large-scale functional genomics investigations.

  17. Sexual Functioning and Behavior of Men with Body Dysmorphic Disorder Concerning Penis Size Compared with Men Anxious about Penis Size and with Controls: A Cohort Study

    Directory of Open Access Journals (Sweden)

    David Veale, MD, FRCPsych

    2015-09-01

    Conclusion: Men with BDD are more likely to have erectile dysfunction and less satisfaction with intercourse than controls but maintain their libido. Further research is required to develop and evaluate a psychological intervention for such men with adequate outcome measures. Veale D, Miles S, Read J, Troglia A, Wylie K, and Muir G. Sexual functioning and behavior of men with body dysmorphic disorder concerning penis size compared with men anxious about penis size and with controls: A cohort study. Sex Med 2015;3:147–155.

  18. Multi-Functional Carbon Fibre Composites using Carbon Nanotubes as an Alternative to Polymer Sizing

    Science.gov (United States)

    Pozegic, T. R.; Anguita, J. V.; Hamerton, I.; Jayawardena, K. D. G. I.; Chen, J.-S.; Stolojan, V.; Ballocchi, P.; Walsh, R.; Silva, S. R. P.

    2016-11-01

    Carbon fibre reinforced polymers (CFRP) were introduced to the aerospace, automobile and civil engineering industries for their high strength and low weight. A key feature of CFRP is the polymer sizing - a coating applied to the surface of the carbon fibres to assist handling, improve the interfacial adhesion between fibre and polymer matrix and allow this matrix to wet-out the carbon fibres. In this paper, we introduce an alternative material to the polymer sizing, namely carbon nanotubes (CNTs) on the carbon fibres, which in addition imparts electrical and thermal functionality. High quality CNTs are grown at a high density as a result of a 35 nm aluminium interlayer which has previously been shown to minimise diffusion of the catalyst in the carbon fibre substrate. A CNT modified-CFRP show 300%, 450% and 230% improvements in the electrical conductivity on the ‘surface’, ‘through-thickness’ and ‘volume’ directions, respectively. Furthermore, through-thickness thermal conductivity calculations reveal a 107% increase. These improvements suggest the potential of a direct replacement for lightning strike solutions and to enhance the efficiency of current de-icing solutions employed in the aerospace industry.

  19. Functional size of human visual area V1: a neural correlate of top-down attention.

    Science.gov (United States)

    Verghese, Ashika; Kolbe, Scott C; Anderson, Andrew J; Egan, Gary F; Vidyasagar, Trichur R

    2014-06-01

    Heavy demands are placed on the brain's attentional capacity when selecting a target item in a cluttered visual scene, or when reading. It is widely accepted that such attentional selection is mediated by top-down signals from higher cortical areas to early visual areas such as the primary visual cortex (V1). Further, it has also been reported that there is considerable variation in the surface area of V1. This variation may impact on either the number or specificity of attentional feedback signals and, thereby, the efficiency of attentional mechanisms. In this study, we investigated whether individual differences between humans performing attention-demanding tasks can be related to the functional area of V1. We found that those with a larger representation in V1 of the central 12° of the visual field as measured using BOLD signals from fMRI were able to perform a serial search task at a faster rate. In line with recent suggestions of the vital role of visuo-spatial attention in reading, the speed of reading showed a strong positive correlation with the speed of visual search, although it showed little correlation with the size of V1. The results support the idea that the functional size of the primary visual cortex is an important determinant of the efficiency of selective spatial attention for simple tasks, and that the attentional processing required for complex tasks like reading are to a large extent determined by other brain areas and inter-areal connections. Copyright © 2014 Elsevier Inc. All rights reserved.

  20. Functional Marker Development and Effect Analysis of Grain Size Gene GW2 in Extreme Grain Size Germplasm in Rice

    Directory of Open Access Journals (Sweden)

    Zhang Ya-dong

    2015-03-01

    Full Text Available GW2 is an important gene that regulates grain width and weight. We used cDNA clone to obtain the sequences of GW2 from large- and small-grained rice varieties, TD70 and Kasalath, respectively. Then, we developed a dCAPS (derived cleaved amplified polymorphic sequence marker on the basis of the sequence difference between functional and nonfunctional GW2 genes to analyze the genotypes and phenotypes of recombinant inbred lines. Results showed that the sequence of GW2TD70 had a single nucleotide deletion at site 316 that generates a termination codon. This codon terminated the GW2 protein in advance. By contrast, the sequence of GW2Kasalath encoded an intact protein. A novel dCAPS marker was designed in accordance with a base A deletion at site 316 of the sequence. After the PCR product was digested by ApoI, TD70 showed 21 and 30 bp fragments, and Kasalath showed a 51 bp fragment. Up to 82 lines contained GW2TD70, and 158 lines contained GW2Kasalath. The lines that contained TD70 alleles displayed substantial increases in width and 1000-grain weight. This result suggested that GW2 played a critical role in rice breeding.

  1. Effects of climate on size structure and functioning of aquatic food webs

    NARCIS (Netherlands)

    Lacerot, G.

    2010-01-01

    In aquatic food webs, the role of body size is notoriously strong. It is also well known that temperature has an effect on body size. For instance, Bergmann’s rule states that body size increases from warm to cold climates. This thesis addresses the question how climate shapes the size structure of

  2. Four-junction superconducting circuit

    Science.gov (United States)

    Qiu, Yueyin; Xiong, Wei; He, Xiao-Ling; Li, Tie-Fu; You, J. Q.

    2016-01-01

    We develop a theory for the quantum circuit consisting of a superconducting loop interrupted by four Josephson junctions and pierced by a magnetic flux (either static or time-dependent). In addition to the similarity with the typical three-junction flux qubit in the double-well regime, we demonstrate the difference of the four-junction circuit from its three-junction analogue, including its advantages over the latter. Moreover, the four-junction circuit in the single-well regime is also investigated. Our theory provides a tool to explore the physical properties of this four-junction superconducting circuit. PMID:27356619

  3. Left atrial size and function as predictors of new-onset of atrial fibrillation in patients with asymptomatic aortic stenosis

    DEFF Research Database (Denmark)

    Bang, Casper Niels Furbo; Dalsgaard, Morten; Greve, Anders

    2013-01-01

    Left atrial (LA) size and function change with chronically increased left ventricular (LV) filling pressures. It remains unclear whether these variations in LA parameters can predict new-onset atrial fibrillation (AF) in asymptomatic patients with aortic stenosis (AS).......Left atrial (LA) size and function change with chronically increased left ventricular (LV) filling pressures. It remains unclear whether these variations in LA parameters can predict new-onset atrial fibrillation (AF) in asymptomatic patients with aortic stenosis (AS)....

  4. A Research Note on the Relationship between the Control Environment and the Size of the Internal Audit Function in Belguim

    OpenAIRE

    G. SARENS

    2007-01-01

    This study attempts to contribute to the literature by developing three control environment variables, reflecting the contemporary context in which internal auditing is operating, and testing how these variables are related with the size of the internal audit function. Data were collected through a questionnaire sent to Chief Audit Executives. The new control environment variables turned out to be relevant when studying the size of the internal audit function. The results show that the degree...

  5. Size-dependent vibrations of post-buckled functionally graded Mindlin rectangular microplates

    Directory of Open Access Journals (Sweden)

    R. Ansari

    Full Text Available In this paper, the free vibration behavior of post-buckled functionally graded (FG Mindlin rectangular microplates are described based on the modified couple stress theory (MCST. This theory enables the consideration of the size-effect through introducing material length scale parameters. The FG microplates made of a mixture of metal and ceramic are considered whose volume fraction of components is expressed by a power law function. By means of Hamilton's principle, the nonlinear governing equations and associated boundary conditions are derived for FG micro-plates in the postbuckling domain. The governing equations and boundary conditions are then discretized by using the generalized differential quadrature (GDQ method before solving numerically by the pseudo-arclength continuation technique. In the solution procedure, the postbuckling problem of microplates is investigated first. Afterwards, the free vibration of microplates around the buckled configuration is discussed. The effects of dimensionless length scale parameter, material gradient index and aspect ratio on the on the postbuckling path and frequency of FG microplates subject to arbitrary edge supports are thoroughly discussed.

  6. Junctional transfer in cultured vascular endothelium: II. Dye and nucleotide transfer

    International Nuclear Information System (INIS)

    Larson, D.M.; Sheridan, J.D.

    1985-01-01

    Vascular endothelial cultures, derived from large vessels, retain many of the characteristics of their in vivo counterparts. However, the observed reduction in size and complexity of intercellular gap and tight junctions in these cultured cells suggests that important functions, thought to be mediated by these structures, may be altered in vitro. In continuing studies on intercellular communication in vessel wall cells, the authors have quantitated the extent of junctional transfer of small molecular tracers (the fluorescent dye Lucifer Yellow CH and tritiated uridine nucleotides) in confluent cultures of calf aortic (BAEC) and umbilical vein (BVEC) endothelium. Both BAEC and BVEC show extensive (and quantitatively equivalent) dye and nucleotide transfer. As an analogue of intimal endothelium, the authors have also tested dye transfer in freshly isolated sheets of endothelium. Transfer in BAEC and BVEC sheets was more rapid, extensive and homogeneous than in the cultured cells, implying a reduction in molecular coupling as endothelium adapts to culture conditions. In addition, they have documented heterocellular nucleotide transfer between cultured endothelium and vascular smooth muscle cells, of particular interest considering the prevalence of ''myo-endothelial'' junctions in vivo. These data yield further information on junctional transfer in cultured vascular endothelium and have broad implications for the functional integration of the vessel wall in the physiology and pathophysiology of the vasculature

  7. Tunable Nitride Josephson Junctions.

    Energy Technology Data Exchange (ETDEWEB)

    Missert, Nancy A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Henry, Michael David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lewis, Rupert M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Howell, Stephen W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wolfley, Steven L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brunke, Lyle Brent [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wolak, Matthaeus [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2017-12-01

    We have developed an ambient temperature, SiO2/Si wafer - scale process for Josephson junctions based on Nb electrodes and Ta x N barriers with tunable electronic properties. The films are fabricated by magnetron sputtering. The electronic properties of the TaxN barriers are controlled by adjusting the nitrogen flow during sputtering. This technology offers a scalable alternative to the more traditional junctions based on AlOx barriers for low - power, high - performance computing.

  8. Individual and species-specific traits explain niche size and functional role in spiders as generalist predators.

    Science.gov (United States)

    Sanders, Dirk; Vogel, Esther; Knop, Eva

    2015-01-01

    The function of a predator within a community is greatly based on its trophic niche, that is the number and the strength of feeding links. In generalist predators, which feed on a wide range of prey, the size and position of the trophic niche is likely determined by traits such as hunting mode, the stratum they occur in, their body size and age. We used stable isotope analyses ((13)C and (15)N) to measure the trophic niche size of nine spider species within a forest hedge community and tested for species traits and individual traits that influence stable isotope enrichment, niche size and resource use. The spiders Enoplognatha, Philodromus, Floronia, and Heliophanus had large isotopic niches, which correspond to a more generalistic feeding behaviour. In contrast, Araneus, Metellina and Agelena, as top predators in the system, had rather narrow niches. We found a negative correlation between trophic position and niche size. Differences in trophic position in spiders were explained by body size, hunting modes and stratum, while niche size was influenced by hunting mode. In Philodromus, the size of the trophic niche increased significantly with age. Fitting spiders to functional groups according to their mean body size, hunting mode and their habitat domain resulted in largely separated niches, which indicates that these traits are meaningful for separating functional entities in spiders. Functional groups based on habitat domain (stratum) caught the essential functional differences between the species with species higher up in the vegetation feeding on flying insects and herb and ground species also preying on forest floor decomposers. Interestingly, we found a gradient from large species using a higher habitat domain and having a smaller niche to smaller species foraging closer to the ground and having a larger niche. This shows that even within generalist predators, such as spiders, there is a gradient of specialism that can be predicted by functional traits.

  9. Performance of two-dimensional Doppler echocardiography for the assessment of infarct size and left ventricular function in rats

    Directory of Open Access Journals (Sweden)

    Nozawa E.

    2006-01-01

    Full Text Available Although echocardiography has been used in rats, few studies have determined its efficacy for estimating myocardial infarct size. Our objective was to estimate the myocardial infarct size, and to evaluate anatomic and functional variables of the left ventricle. Myocardial infarction was produced in 43 female Wistar rats by ligature of the left coronary artery. Echocardiography was performed 5 weeks later to measure left ventricular diameter and transverse area (mean of 3 transverse planes, infarct size (percentage of the arc with infarct on 3 transverse planes, systolic function by the change in fractional area, and diastolic function by mitral inflow parameters. The histologic measurement of myocardial infarction size was similar to the echocardiographic method. Myocardial infarct size ranged from 4.8 to 66.6% when determined by histology and from 5 to 69.8% when determined by echocardiography, with good correlation (r = 0.88; P < 0.05; Pearson correlation coefficient. Left ventricular diameter and mean diastolic transverse area correlated with myocardial infarct size by histology (r = 0.57 and r = 0.78; P < 0.0005. The fractional area change ranged from 28.5 ± 5.6 (large-size myocardial infarction to 53.1 ± 1.5% (control and correlated with myocardial infarct size by echocardiography (r = -0.87; P < 0.00001 and histology (r = -0.78; P < 00001. The E/A wave ratio of mitral inflow velocity for animals with large-size myocardial infarction (5.6 ± 2.7 was significantly higher than for all others (control: 1.9 ± 0.1; small-size myocardial infarction: 1.9 ± 0.4; moderate-size myocardial infarction: 2.8 ± 2.3. There was good agreement between echocardiographic and histologic estimates of myocardial infarct size in rats.

  10. Left Atrial Size and Function in a Canine Model of Chronic Atrial Fibrillation and Heart Failure

    Science.gov (United States)

    Goldberg, Adam; Kusunose, Kenya; Qamruddin, Salima; Rodriguez, L. Leonardo; Mazgalev, Todor N.; Griffin, Brian P.; Van Wagoner, David R.; Zhang, Youhua; Popović, Zoran B.

    2016-01-01

    Background Our aim was to assess how atrial fibrillation (AF) induction, chronicity, and RR interval irregularity affect left atrial (LA) function and size in the setting of underlying heart failure (HF), and to determine whether AF effects can be mitigated by vagal nerve stimulation (VNS). Methods HF was induced by 4-weeks of rapid ventricular pacing in 24 dogs. Subsequently, AF was induced and maintained by atrial pacing at 600 bpm. Dogs were randomized into control (n = 9) and VNS (n = 15) groups. In the VNS group, atrioventricular node fat pad stimulation (310 μs, 20 Hz, 3–7 mA) was delivered continuously for 6 months. LA volume and LA strain data were calculated from bi-weekly echocardiograms. Results RR intervals decreased with HF in both groups (p = 0.001), and decreased further during AF in control group (p = 0.014), with a non-significant increase in the VNS group during AF. LA size increased with HF (p<0.0001), with no additional increase during AF. LA strain decreased with HF (p = 0.025) and further decreased after induction of AF (p = 0.0001). LA strain decreased less (p = 0.001) in the VNS than in the control group. Beat-by-beat analysis showed a curvilinear increase of LA strain with longer preceding RR interval, (r = 0.45, p <0.0001) with LA strain 1.1% higher (p = 0.02) in the VNS-treated animals, independent of preceding RR interval duration. The curvilinear relationship between ratio of preceding and pre-preceding RR intervals, and subsequent LA strain was weaker, (r = 0.28, p = 0.001). However, VNS-treated animals again had higher LA strain (by 2.2%, p = 0.002) independently of the ratio of preceding and pre-preceding RR intervals. Conclusions In the underlying presence of pacing-induced HF, AF decreased LA strain, with little impact on LA size. LA strain depends on the preceding RR interval duration. PMID:26771573

  11. Zonula occludens toxin structure-function analysis. Identification of the fragment biologically active on tight junctions and of the zonulin receptor binding domain.

    Science.gov (United States)

    Di Pierro, M; Lu, R; Uzzau, S; Wang, W; Margaretten, K; Pazzani, C; Maimone, F; Fasano, A

    2001-06-01

    Zonula occludens toxin (Zot) is an enterotoxin elaborated by Vibrio cholerae that increases intestinal permeability by interacting with a mammalian cell receptor with subsequent activation of intracellular signaling leading to the disassembly of the intercellular tight junctions. Zot localizes in the bacterial outer membrane of V. cholerae with subsequent cleavage and secretion of a carboxyl-terminal fragment in the host intestinal milieu. To identify the Zot domain(s) directly involved in the protein permeating effect, several zot gene deletion mutants were constructed and tested for their biological activity in the Ussing chamber assay and their ability to bind to the target receptor on intestinal epithelial cell cultures. The Zot biologically active domain was localized toward the carboxyl terminus of the protein and coincided with the predicted cleavage product generated by V. cholerae. This domain shared a putative receptor-binding motif with zonulin, the Zot mammalian analogue involved in tight junction modulation. Amino acid comparison between the Zot active fragment and zonulin, combined with site-directed mutagenesis experiments, confirmed the presence of an octapeptide receptor-binding domain toward the amino terminus of the processed Zot.

  12. Claudin-4 Overexpression in Epithelial Ovarian Cancer Is Associated with Hypomethylation and Is a Potential Target for Modulation of Tight Junction Barrier Function Using a C-Terminal Fragment of Clostridium perfringens Enterotoxin

    Directory of Open Access Journals (Sweden)

    Babak Litkouhi

    2007-04-01

    Full Text Available BACKGROUND: Claudin-4, a tight junction (TJ protein and receptor for the C-terminal fragment of Clostridium perfringens enterotoxin (C-CPE, is overexpressed in epithelial ovarian cancer (EOC. Previous research suggests DNA methylation is a mechanism for claudin-4 overexpression in cancer and that C-CPE acts as an absorption-enhancing agent in claudin-4expressing cells. We sought to correlate claudin-4 overexpression in EOC with clinical outcomes and TJ barrier function, investigate DNA methylation as a mechanism for overexpression, and evaluate the effect of C-CPE on the TJ. METHODS: Claudin-4 expression in EOC was quantified and correlated with clinical outcomes. Claudin-4 methylation status was determined, and claudin-4-negative cell lines were treated with a demethylating agent. Electric cell-substrate impedance sensing was used to calculate junctional (paracellular resistance (Rb in EOC cells after claudin-4 silencing and after C-CPE treatment. RESULTS: Claudin4 overexpression in EOC does not correlate with survival or other clinical endpoints and is associated with hypomethylation. Claudin-4 overexpression correlates with Rb and C-CPE treatment of EOC cells significantly decreased Rb in a dose- and claudin-4-dependent noncytotoxic manner. CONCLUSIONS: C-CPE treatment of EOC cells leads to altered TJ function. Further research is needed to determine the potential clinical applications of C-CPE in EOC drug delivery strategies.

  13. Quantum Junction Solar Cells

    KAUST Repository

    Tang, Jiang; Liu, Huan; Zhitomirsky, David; Hoogland, Sjoerd; Wang, Xihua; Furukawa, Melissa; Levina, Larissa; Sargent, Edward H.

    2012-01-01

    -performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO 2); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising

  14. Phase-dependent noise in Josephson junctions

    Science.gov (United States)

    Sheldon, Forrest; Peotta, Sebastiano; Di Ventra, Massimiliano

    2018-03-01

    In addition to the usual superconducting current, Josephson junctions (JJs) support a phase-dependent conductance related to the retardation effect of tunneling quasi-particles. This introduces a dissipative current with a memory-resistive (memristive) character that should also affect the current noise. By means of the microscopic theory of tunnel junctions we compute the complete current autocorrelation function of a Josephson tunnel junction and show that this memristive component gives rise to both a previously noted phase-dependent thermal noise, and an undescribed non-stationary, phase-dependent dynamic noise. As experiments are approaching ranges in which these effects may be observed, we examine the form and magnitude of these processes. Their phase dependence can be realized experimentally as a hysteresis effect and may be used to probe defects present in JJ based qubits and in other superconducting electronics applications.

  15. Effects on heart function of neoadjuvant chemotherapy and chemoradiotherapy in patients with cancer in the esophagus or gastroesophageal junction – a prospective cohort pilot study within a randomized clinical trial

    International Nuclear Information System (INIS)

    Lund, Mikael; Alexandersson von Döbeln, Gabriella; Nilsson, Magnus; Winter, Reidar; Lundell, Lars; Tsai, Jon A; Kalman, Sigridur

    2015-01-01

    Neoadjuvant therapy for cancer of the esophagus or gastroesophageal (GE)-junction is well established. The pros and cons of chemoradiotherapy and chemotherapy are debated. Chemoradiotherapy might impair cardiac function eliciting postoperative morbidity. The aim of this pilot study was to describe acute changes in left ventricular function following chemoradiotherapy or chemotherapy. Patients with esophageal and (GE)-junction cancer enrolled at our center into a multicenter trial comparing neoadjuvant chemoradiotherapy and chemotherapy were eligible. Patients were randomized to receive cisplatin and 5-fluorouracil with or without the addition of 40 Gy radiotherapy prior to surgery. Left ventricular function was evaluated using echocardiography and plasma N-Terminal Pro-B-Type Natriuretic Peptide (NT-proBNP) before and after neoadjuvant treatment. The primary outcome measure was left ventricular global strain (GS). Clinical effects were assessed using repeated exercise tests. Linear mixed models were used to analyze the effects of treatment group, and the interaction between groups. 40 patients participated (chemoradiotherapy, n = 17; chemotherapy, n = 23). In the chemoradiotherapy group there was no change in left ventricular global strain but mitral annular plane systolic excursion (MAPSE) of the ventricular septum, early diastolic filling velocity (E-velocity), and the ratio of early to late ventricular filling velocities (E/A ratio) decreased significantly (p = 0.02, p = 0.01, and p = 0.03, respectively). No changes were observed in the chemotherapy group. There was a trend towards an interaction effect for MAPSE sept and E (p = 0.09 and p = 0.09). NT-proBNP increased following chemoradiotherapy (p = 0.05) but not after chemotherapy (p > 0.99), and there was a trend towards an interaction effect (p = 0.07). Working capacity decreased following neoadjuvant treatment (chemoradiotherapy p = 0.001, chemotherapy p = 0.03) and was more pronounced after

  16. Behavior of tight-junction, adherens-junction and cell polarity proteins during HNF-4α-induced epithelial polarization

    International Nuclear Information System (INIS)

    Satohisa, Seiro; Chiba, Hideki; Osanai, Makoto; Ohno, Shigeo; Kojima, Takashi; Saito, Tsuyoshi; Sawada, Norimasa

    2005-01-01

    We previously reported that expression of tight-junction molecules occludin, claudin-6 and claudin-7, as well as establishment of epithelial polarity, was triggered in mouse F9 cells expressing hepatocyte nuclear factor (HNF)-4α [H. Chiba, T. Gotoh, T. Kojima, S. Satohisa, K. Kikuchi, M. Osanai, N. Sawada. Hepatocyte nuclear factor (HNF)-4α triggers formation of functional tight junctions and establishment of polarized epithelial morphology in F9 embryonal carcinoma cells, Exp. Cell Res. 286 (2003) 288-297]. Using these cells, we examined in the present study behavior of tight-junction, adherens-junction and cell polarity proteins and elucidated the molecular mechanism behind HNF-4α-initiated junction formation and epithelial polarization. We herein show that not only ZO-1 and ZO-2, but also ZO-3, junctional adhesion molecule (JAM)-B, JAM-C and cell polarity proteins PAR-3, PAR-6 and atypical protein kinase C (aPKC) accumulate at primordial adherens junctions in undifferentiated F9 cells. In contrast, CRB3, Pals1 and PATJ appeared to exhibit distinct subcellular localization in immature cells. Induced expression of HNF-4α led to translocation of these tight-junction and cell polarity proteins to beltlike tight junctions, where occludin, claudin-6 and claudin-7 were assembled, in differentiated cells. Interestingly, PAR-6, aPKC, CRB3 and Pals1, but not PAR-3 or PATJ, were also concentrated on the apical membranes in differentiated cells. These findings indicate that HNF-4α provokes not only expression of tight-junction adhesion molecules, but also modulation of subcellular distribution of junction and cell polarity proteins, resulting in junction formation and epithelial polarization

  17. Characterization, scaling, and partial representation of diffuse and discrete input junctions to CA3 hippocampus.

    Science.gov (United States)

    Ascarrunz, F G; Kisley, M A; Flach, K A; Hamilton, R W; MacGregor, R J

    1995-07-01

    This paper applies a general mathematical system for characterizing and scaling functional connectivity and information flow across the diffuse (EC) and discrete (DG) input junctions to the CA3 hippocampus. Both gross connectivity and coordinated multiunit informational firing patterns are quantitatively characterized in terms of 32 defining parameters interrelated by 17 equations, and then scaled down according to rules for uniformly proportional scaling and for partial representation. The diffuse EC-CA3 junction is shown to be uniformly scalable with realistic representation of both essential spatiotemporal cooperativity and coordinated firing patterns down to populations of a few hundred neurons. Scaling of the discrete DG-CA3 junction can be effected with a two-step process, which necessarily deviates from uniform proportionality but nonetheless produces a valuable and readily interpretable reduced model, also utilizing a few hundred neurons in the receiving population. Partial representation produces a reduced model of only a portion of the full network where each model neuron corresponds directly to a biological neuron. The mathematical analysis illustrated here shows that although omissions and distortions are inescapable in such an application, satisfactorily complete and accurate models the size of pattern modules are possible. Finally, the mathematical characterization of these junctions generates a theory which sees the DG as a definer of the fine structure of embedded traces in the hippocampus and entire coordinated patterns of sequences of 14-cell links in CA3 as triggered by the firing of sequences of individual neurons in DG.

  18. Quantum size correction to the work function and the centroid of excess charge in positively ionized simple metal clusters

    Directory of Open Access Journals (Sweden)

    M. Payami

    2003-12-01

    Full Text Available  In this work, we have shown the important role of the finite-size correction to the work function in predicting the correct position of the centroid of excess charge in positively charged simple metal clusters with different values . For this purpose, firstly we have calculated the self-consistent Kohn-Sham energies of neutral and singly-ionized clusters with sizes in the framework of local spin-density approximation and stabilized jellium model (SJM as well as simple jellium model (JM with rigid jellium. Secondly, we have fitted our results to the asymptotic ionization formulas both with and without the size correction to the work function. The results of fittings show that the formula containing the size correction predict a correct position of the centroid inside the jellium while the other predicts a false position, outside the jellium sphere.

  19. Quantum size correction to the work function and centroid of excess charge in positively ionized simple metal clusters

    International Nuclear Information System (INIS)

    Payami, M.

    2004-01-01

    In this work, we have shown the important role of the finite-size correction to the work function in predicting the correct position of the centroid of excess charge in positively charged simple metal clusters with different r s values (2≤ r s ≥ 7). For this purpose, firstly we have calculated the self-consistent Kohn-Sham energies of neutral and singly-ionized clusters with sizes 2≤ N ≥100 in the framework of local spin-density approximation and stabilized jellium model as well as simple jellium model with rigid jellium. Secondly, we have fitted our results to the asymptotic ionization formulas both with and without the size correction to the work function. The results of fittings show that the formula containing the size correction predict a correct position of the centroid inside the jellium while the other predicts a false position, outside the jellium sphere

  20. Size structure of marine soft-bottom macrobenthic communities across natural habitat gradients: implications for productivity and ecosystem function.

    Directory of Open Access Journals (Sweden)

    Tara A Macdonald

    Full Text Available Size distributions of biotic assemblages are important modifiers of productivity and function in marine sediments. We investigated the distribution of proportional organic biomass among logarithmic size classes (2(-6J to 2(16J in the soft-bottom macrofaunal communities of the Strait of Georgia, Salish Sea on the west coast of Canada. The study examines how size structure is influenced by 3 fundamental habitat descriptors: depth, sediment percent fines, and organic flux (modified by quality. These habitat variables are uncorrelated in this hydrographically diverse area, thus we examine their effects in combination and separately. Cluster analyses and cumulative biomass size spectra reveal clear and significant responses to each separate habitat variable. When combined, habitat factors result in three distinct assemblages: (1 communities with a high proportion of biomass in small organisms, typical of shallow areas (3 g C/m(2/yr/δ(15N from the Fraser River; and (3 communities with biomass dominated by moderately large organisms, but lacking the smallest and largest size classes, typical of deep, fine sediments experiencing low modified organic flux (<3.0 gC/m(2/yr/δ(15N. The remaining assemblages had intermediate habitat types and size structures. Sediment percent fines and flux appear to elicit threshold responses in size structure, whereas depth has the most linear influence on community size structure. The ecological implications of size structure in the Strait of Georgia relative to environmental conditions, secondary production and sediment bioturbation are discussed.

  1. Isotope source apportionment of carbonaceous aerosol as a function of particle size and thermal refractiveness

    Science.gov (United States)

    Masalaite, Agne; Holzinger, Rupert; Remeikis, Vidmantas; Röckmann, Thomas; Dusek, Ulrike

    2016-04-01

    The stable carbon isotopes can be used to get information about sources and processing of carbonaceous aerosol. We will present results from source apportionment of carbonaceous aerosol as a function of particle size thermal refractiveness. Separate source apportionment for particles smaller than 200 nm and for different carbon volatility classes are rarely reported and give new insights into aerosol sources in the urban environment. Stable carbon isotope ratios were measured for the organic carbon (OC) fraction and total carbon (TC) of MOUDI impactor samples that were collected on a coastal site (Lithuania) during the winter 2012 and in the city of Vilnius (Lithuania) during the winter of 2009. The 11 impactor stages spanned a size range from 0.056 to 18 μm, but only the 6 stages in the submicron range were analysed. The δ13C values of bulk total carbon (δ13CTC) were determined with an elemental analyser (Flash EA 1112) coupled with an isotope ratio mass spectrometer (Thermo Finnigan Delta Plus Advantage) (EA - IRMS). Meanwhile δ13COC was measured using thermal-desorption isotope ratio mass spectrometry (IRMS) system. This allows a rough separation of the more volatile OC fraction (desorbed in the oven of IRMS up to 250 0C) from the more refractory fraction (desorbed up to 400 0C). In this study we investigated the composition of organic aerosol desorbed from filter samples at different temperatures using the thermal-desorption proton-transfer-reaction mass spectrometry (TD-PTR-MS) technique. During winter-time in Lithuania we expect photochemistry and biogenic emissions to be of minor importance. The main sources of aerosol carbon should be fossil fuel and biomass combustion. In both sites, the coastal and the urban site, δ13C measurements give a clear indication that the source contributions differ for small and large particles. Small particles < 200 nm are depleted in 13C with respect to larger particles by 1 - 2 ‰Ṫhis shows that OC in small particle

  2. Temporal correlations and structural memory effects in break junction measurements

    DEFF Research Database (Denmark)

    Magyarkuti, A.; Lauritzen, Kasper Primdal; Balogh, Zoltan Imre

    2017-01-01

    that correlations between the opening and subsequent closing traces may indicate structural memory effects in atomic-sized metallic and molecular junctions. Applying these methods on measured and simulated gold metallic contacts as a test system, we show that the surface diffusion induced flattening of the broken......-molecule junctions, we demonstrate pronounced contact memory effects and recovery of the molecule for junctions breaking before atomic chains are formed. However, if chains are pulled the random relaxation of the chain and molecule after rupture prevents opening-closing correlations....

  3. AFM topographies of densely packed nanoparticles: a quick way to determine the lateral size distribution by autocorrelation function analysis

    International Nuclear Information System (INIS)

    Fekete, L.; Kůsová, K.; Petrák, V.; Kratochvílová, I.

    2012-01-01

    The distribution of sizes is one of the basic characteristics of nanoparticles. Here, we propose a novel way to determine the lateral distribution of sizes from AFM topographies. Our algorithm is based on the autocorrelation function and can be applied both on topographies containing spatially separated and densely packed nanoparticles as well as on topographies of polycrystalline films. As no manual treatment is required, this algorithm can be easily automatable for batch processing. The algorithm works in principle with any kind of spatially mapped information (AFM current maps, optical microscope images, etc.), and as such has no size limitations. However, in the case of AFM topographies, the tip/sample convolution effects will be the factor limiting the smallest size to which the algorithm is applicable. Here, we demonstrate the usefulness of this algorithm on objects with sizes ranging between 20 nm and 1.5 μm.

  4. Autonomous nodule of the thyroid: correlation of patient age, nodule size, and functional status

    International Nuclear Information System (INIS)

    Blum, M.; Shenkman, L.; Hollander, C.S.

    1975-01-01

    In light of new techniques for measuring circulating thyroid hormones and for studying the thyroid gland, we present our experience with 35 patients with solitary autonomous nodules of the thyroid to define more precisely the clinical course of patients with this disorder. The patients ranged in age from 19 to 80 years and 31 of the 35 were female. Younger patients were generally euthyroid and sought attention because of a thyroid mass; virtually all older patients were hyperthyroid. Eighteen had obvious clinical features of hyperthyroidism and 5 over age 70 had apathetic hyperthyroidism; all 5 of the elderly and 13 of the 18 under age 70 had elevated thyroxine (T 4 ) and triiodothyronine (T 3 ) levels. Isolated elevation of T 3 and elevated basal metabolic rate were observed in 5 previously untreated clinically hyperthyroid young patients. In each of these, thyroid uptake of 131 I was not suppressible with exogenous T 3 and BMR was elevated in those tested. Two elderly patients, who had previously been treated for conventional hyperthyroidism with radioactive iodine, had T 3 toxicosis when hyperthyroidism recurred. There was a strong positive correlation between the age of the patient, the size of the nodule and the thyroid functional state. The mean area of the nodules projected on 131 I rectilinear scan for euthyroid patients was 5.1 cm 2 . The mean area of the nodules in hyperthyroid subjects was significantly higher, 13.4 cm 2 in patients with T 3 toxicosis and 19.3 cm 2 in subjects with conventional hyperthyroidism. Progression from a euthyroid state to hyperthyroidism was observed in four patients. One of these became thyrotoxic within days after an injection of iodinated contrast medium. Spontaneous resolution of nodules occurred in two patients

  5. Josephson junctions array resonators

    Energy Technology Data Exchange (ETDEWEB)

    Gargiulo, Oscar; Muppalla, Phani; Mirzaei, Iman; Kirchmair, Gerhard [Institute for Quantum Optics and Quantum Information, Innsbruck (Austria)

    2016-07-01

    We present an experimental analysis of the self- and cross-Kerr effect of extended plasma resonances in Josephson junction chains. The chain consists of 1600 individual junctions and we can measure quality factors in excess of 10000. The Kerr effect manifests itself as a frequency shift that depends linearly on the number of photons in a resonant mode. By changing the input power we are able to measure this frequency shift on a single mode (self-kerr). By changing the input power on another mode while measuring the same one, we are able to evaluate the cross-kerr effect. We can measure the cross-Kerr effect by probing the resonance frequency of one mode while exciting another mode of the array with a microwave drive.

  6. Curved Josephson junction

    International Nuclear Information System (INIS)

    Dobrowolski, Tomasz

    2012-01-01

    The constant curvature one and quasi-one dimensional Josephson junction is considered. On the base of Maxwell equations, the sine–Gordon equation that describes an influence of curvature on the kink motion was obtained. It is showed that the method of geometrical reduction of the sine–Gordon model from three to lower dimensional manifold leads to an identical form of the sine–Gordon equation. - Highlights: ► The research on dynamics of the phase in a curved Josephson junction is performed. ► The geometrical reduction is applied to the sine–Gordon model. ► The results of geometrical reduction and the fundamental research are compared.

  7. Mechanisms shaping size structure and functional diversity of phytoplankton communities in the ocean

    Science.gov (United States)

    Acevedo-Trejos, Esteban; Brandt, Gunnar; Bruggeman, Jorn; Merico, Agostino

    2015-01-01

    The factors regulating phytoplankton community composition play a crucial role in structuring aquatic food webs. However, consensus is still lacking about the mechanisms underlying the observed biogeographical differences in cell size composition of phytoplankton communities. Here we use a trait-based model to disentangle these mechanisms in two contrasting regions of the Atlantic Ocean. In our model, the phytoplankton community can self-assemble based on a trade-off emerging from relationships between cell size and (1) nutrient uptake, (2) zooplankton grazing, and (3) phytoplankton sinking. Grazing ‘pushes’ the community towards larger cell sizes, whereas nutrient uptake and sinking ‘pull’ the community towards smaller cell sizes. We find that the stable environmental conditions of the tropics strongly balance these forces leading to persistently small cell sizes and reduced size diversity. In contrast, the seasonality of the temperate region causes the community to regularly reorganize via shifts in species composition and to exhibit, on average, bigger cell sizes and higher size diversity than in the tropics. Our results raise the importance of environmental variability as a key structuring mechanism of plankton communities in the ocean and call for a reassessment of the current understanding of phytoplankton diversity patterns across latitudinal gradients. PMID:25747280

  8. Effect of solar-cell junction geometry on open-circuit voltage

    Science.gov (United States)

    Weizer, V. G.; Godlewski, M. P.

    1985-01-01

    Simple analytical models have been found that adequately describe the voltage behavior of both the stripe junction and dot junction grating cells as a function of junction area. While the voltage in the former case is found to be insensitive to junction area reduction, significant voltage increases are shown to be possible for the dot junction cell. With regard to cells in which the junction area has been increased in a quest for better performance, it was found that (1) texturation does not affect the average saturation current density J0, indicating that the texturation process is equivalent to a simple extension of junction area by a factor of square root of 3 and (2) the vertical junction cell geometry produces a sizable decrease in J0 that, unfortunately, is more than offset by the effects of attendant areal increases.

  9. Specific activity of uranium and thorium in marketable rock phosphate as a function of particle size

    Energy Technology Data Exchange (ETDEWEB)

    Metzger, R; McKlveen, J W [Arizona State Univ., Tempe (USA); Jenkins, R [Phillip Morris Research Center, Richmond, VA (USA); McDowell, W J [Oak Ridge National Lab., TN (USA)

    1980-07-01

    Marketable rock phosphate fertilizer from Florida was classified into seven particle size fractions ranging from 149 ..mu..m to less than 0.5 ..mu..m using a Bahco Microparticle Classifier and air elutriation. The resulting size fractions were assayed for U and /sup 230/Th by solvent extraction and liquid scintillation ..cap alpha..-spectroscopy. Results indicated that the specific activity of U and /sup 230/Th increased with decreasing particle size. Maximum activities of 110 pCi/g U and 50 pCi/g /sup 230/Th were found in particles less than 1.0 ..mu..m in aerodynamic diameter. Qualitative emission spectrographic analysis of the fractions revealed that the concentrations of Al, Cu, Mg, Na, Ti and Zn also increased with decreasing particle size.

  10. Phosphorus content as a function of soil aggregate size and paddy cultivation in highly weathered soils.

    Science.gov (United States)

    Li, Baozhen; Ge, Tida; Xiao, Heai; Zhu, Zhenke; Li, Yong; Shibistova, Olga; Liu, Shoulong; Wu, Jinshui; Inubushi, Kazuyuki; Guggenberger, Georg

    2016-04-01

    Red soils are the major land resource in subtropical and tropical areas and are characterized by low phosphorus (P) availability. To assess the availability of P for plants and the potential stability of P in soil, two pairs of subtropical red soil samples from a paddy field and an adjacent uncultivated upland were collected from Hunan Province, China. Analysis of total P and Olsen P and sequential extraction was used to determine the inorganic and organic P fractions in different aggregate size classes. Our results showed that the soil under paddy cultivation had lower proportions of small aggregates and higher proportions of large aggregates than those from the uncultivated upland soil. The portion of >2-mm-sized aggregates increased by 31 and 20 % at Taoyuan and Guiyang, respectively. The total P and Olsen P contents were 50-150 and 50-300 % higher, respectively, in the paddy soil than those in the upland soil. Higher inorganic and organic P fractions tended to be enriched in both the smallest and largest aggregate size classes compared to the middle size class (0.02-0.2 mm). Furthermore, the proportion of P fractions was higher in smaller aggregate sizes (2 mm). In conclusion, soils under paddy cultivation displayed improved soil aggregate structure, altered distribution patterns of P fractions in different aggregate size classes, and to some extent had enhanced labile P pools.

  11. Schedule-induced drinking as functions of interpellet interval and draught size in the Java macaque.

    Science.gov (United States)

    Allen, J D; Kenshalo, D R

    1978-09-01

    Three Java monkeys received food pellets that were assigned by both ascending and descending series of fixed-time schedules whose values varied between 8 and 256 seconds. The draught size dispensed by a concurrently available water-delivery tube was systematically varied between 1.0 and 0.3 milliliter per lick at various fixed-time values during the second and third series determinations. Session water intake was bitonically related to the interpellet interval and was determined by the interaction of (1) the probability of initiating a drinking bout, which fell off at the highest interpellet intervals and, (2) the size of the bout, which increased directly with increases in interpellet interval. Variations in draught size had little effect on total session intakes, but reduced bout size at draught sizes of 0.5 milliliter and below. Thus, a volume-regulation process of schedule-induced drinking operated generally at the session-intake level, but was limited to higher draught sizes at the bout level.

  12. A Point Mutation in the Exon Junction Complex Factor Y14 Disrupts Its Function in mRNA Cap Binding and Translation Enhancement*

    Science.gov (United States)

    Chuang, Tzu-Wei; Lee, Kuo-Ming; Lou, Yuan-Chao; Lu, Chia-Chen; Tarn, Woan-Yuh

    2016-01-01

    Eukaryotic mRNA biogenesis involves a series of interconnected steps mediated by RNA-binding proteins. The exon junction complex core protein Y14 is required for nonsense-mediated mRNA decay (NMD) and promotes translation. Moreover, Y14 binds the cap structure of mRNAs and inhibits the activity of the decapping enzyme Dcp2. In this report, we show that an evolutionarily conserved tryptophan residue (Trp-73) of Y14 is critical for its binding to the mRNA cap structure. A Trp-73 mutant (W73V) bound weakly to mRNAs and failed to protect them from degradation. However, this mutant could still interact with the NMD and mRNA degradation factors and retained partial NMD activity. In addition, we found that the W73V mutant could not interact with translation initiation factors. Overexpression of W73V suppressed reporter mRNA translation in vitro and in vivo and reduced the level of a set of nascent proteins. These results reveal a residue of Y14 that confers cap-binding activity and is essential for Y14-mediated enhancement of translation. Finally, we demonstrated that Y14 may selectively and differentially modulate protein biosynthesis. PMID:26887951

  13. A Point Mutation in the Exon Junction Complex Factor Y14 Disrupts Its Function in mRNA Cap Binding and Translation Enhancement.

    Science.gov (United States)

    Chuang, Tzu-Wei; Lee, Kuo-Ming; Lou, Yuan-Chao; Lu, Chia-Chen; Tarn, Woan-Yuh

    2016-04-15

    Eukaryotic mRNA biogenesis involves a series of interconnected steps mediated by RNA-binding proteins. The exon junction complex core protein Y14 is required for nonsense-mediated mRNA decay (NMD) and promotes translation. Moreover, Y14 binds the cap structure of mRNAs and inhibits the activity of the decapping enzyme Dcp2. In this report, we show that an evolutionarily conserved tryptophan residue (Trp-73) of Y14 is critical for its binding to the mRNA cap structure. A Trp-73 mutant (W73V) bound weakly to mRNAs and failed to protect them from degradation. However, this mutant could still interact with the NMD and mRNA degradation factors and retained partial NMD activity. In addition, we found that the W73V mutant could not interact with translation initiation factors. Overexpression of W73V suppressed reporter mRNA translation in vitro and in vivo and reduced the level of a set of nascent proteins. These results reveal a residue of Y14 that confers cap-binding activity and is essential for Y14-mediated enhancement of translation. Finally, we demonstrated that Y14 may selectively and differentially modulate protein biosynthesis. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  14. Studies of Redox Equilibria at Elevated Temperatures 2. An Automatic Divided-Function Autoclave and Cell with Flowing Liquid Junction for Electrochemical Measurements on Aqueous Systems.

    Energy Technology Data Exchange (ETDEWEB)

    Johnsson, Kerstin; Lewis, Derek; Pourbaix, Marian de

    1970-10-15

    An apparatus is described that has been developed for electrochemical studies of aqueous systems at temperatures above 100 deg C. It consists essentially of an electrically heated experimental cell enclosed by a separate pressure-vessel the walls of which are kept cool. This construction eliminates or reduces the problems of sealing electrical connections and of the corrosion of the pressure vessel, that commonly arise with conventional, externally-heated autoclaves. Pressure is applied to the cell by means of compressed air, diaphragm valves at the electrolyte outlet automatically maintaining the pressure in the cell about 1 atm lower than that in the pressure vessel. Two independent streams of electrolyte can be pumped into the experimental cell a special form of which has been developed in which may be formed a galvanic cell with a continuously regenerated flowing-liquid junction. In this form the apparatus enables experiments with, for example, one molal chloride solutions with pH 1-10, at temperatures up to about 250 deg C and under pressures up to about 40 atm. The apparatus has been tested in experiments in which classical measurements of the conductance of some aqueous electrolytes have been repeated. Good agreement with the earlier results has been obtained

  15. Point correlation dimension can reveal functional changes caused by gap junction blockers in the 4-aminopyridine in vivo rat epilepsy model

    Energy Technology Data Exchange (ETDEWEB)

    Jardanhazy, Anett [Department of Neurology, University of Szeged, Semmelweis u. 6, Szeged H-6725 (Hungary); Molnar, Mark [Department of Psychophysiology, Institute for Psychology of the Hungarian Academy of Sciences, P.O. Box 398, Budapest H-1394 (Hungary)], E-mail: molnar@cogpsyphy.hu; Jardanhazy, Tamas [Department of Neurology, University of Szeged, Semmelweis u. 6, Szeged H-6725 (Hungary)], E-mail: jt@nepsy.szote.u-szeged.hu

    2009-04-15

    The contribution of gap junction (GJ) blockers to seizure initiation was reexamined by means of an analysis on nonlinear dynamics with point correlation dimension (PD2i) at as well as around the primary focus, and mirror focus in an already active 4-aminopyridine-induced in vivo epilepsy model. From the data base of the ECoGs of anesthetized adult rats treated with quinine, a selective blocker of Cx36, and in combination with an additional broad-spectrum GJ blocker, carbenoxolone, 14 cases of each condition were reexamined with a stationarity insensitive nonlinear PD2i method. The blockade of the Cx36 channels decreased the usual drop of the point correlation dimension at the beginning of the seizures, and this was enhanced by the additional use of the global blocker carbenoxolone. The so-called characteristic DC shift just prior to seizure onset denotes a low dimensional seizure event and the recognizable seizures display very variable, rapidly changing dynamics, as revealed by the PD2i analysis. This nonlinear PD2i analysis demonstrated that the different GJ blockers in the already active epileptic model helped seizure initiation, but exerted inhibitory effects on the seizure onset itself, acting differently on the local components of the network organization generating seizure discharges, possibly changing the coupling strengths and time delays in the GJ-s.

  16. Point correlation dimension can reveal functional changes caused by gap junction blockers in the 4-aminopyridine in vivo rat epilepsy model

    International Nuclear Information System (INIS)

    Jardanhazy, Anett; Molnar, Mark; Jardanhazy, Tamas

    2009-01-01

    The contribution of gap junction (GJ) blockers to seizure initiation was reexamined by means of an analysis on nonlinear dynamics with point correlation dimension (PD2i) at as well as around the primary focus, and mirror focus in an already active 4-aminopyridine-induced in vivo epilepsy model. From the data base of the ECoGs of anesthetized adult rats treated with quinine, a selective blocker of Cx36, and in combination with an additional broad-spectrum GJ blocker, carbenoxolone, 14 cases of each condition were reexamined with a stationarity insensitive nonlinear PD2i method. The blockade of the Cx36 channels decreased the usual drop of the point correlation dimension at the beginning of the seizures, and this was enhanced by the additional use of the global blocker carbenoxolone. The so-called characteristic DC shift just prior to seizure onset denotes a low dimensional seizure event and the recognizable seizures display very variable, rapidly changing dynamics, as revealed by the PD2i analysis. This nonlinear PD2i analysis demonstrated that the different GJ blockers in the already active epileptic model helped seizure initiation, but exerted inhibitory effects on the seizure onset itself, acting differently on the local components of the network organization generating seizure discharges, possibly changing the coupling strengths and time delays in the GJ-s.

  17. Size-dependent accumulation of particles in lysosomes modulates dendritic cell function through impaired antigen degradation

    Directory of Open Access Journals (Sweden)

    Seydoux E

    2014-08-01

    of BMDCs to degrade soluble antigen, without affecting their ability to induce antigen-specific CD4+ T-cell proliferation. Co-localization studies between PS particles and lysosomes using laser scanning confocal microscopy detected a significantly higher frequency of co-localized 20 nm particles as compared with their 1,000 nm counterparts. Neither size of PS particle caused lysosomal leakage, expression of endoplasmic reticulum stress gene markers, or changes in cytokines profiles. Conclusion: These data indicate that although supposedly inert PS nanoparticles did not induce DC activation or alteration in CD4+ T-cell stimulating capacity, 20 nm (but not 1,000 nm PS particles may reduce antigen degradation through interference in the lysosomal compartment. These findings emphasize the importance of performing in-depth analysis of DC function when developing novel approaches for immune modulation with nanoparticles. Keywords: polystyrene particles, nanoparticles, immune modulation, mouse dendritic cells, CD4+ T-cells

  18. Quantum-Tuned Two-Junction Solar Cells

    KAUST Repository

    Wang, Xihua

    2011-01-01

    We report quantum-size-effect tuned tandem solar cells. Our two-junction photovoltaic devices employ light-absorbing material of a single composition and use two rationally-selected nanoparticle sizes to harvest the sun’s broad spectrum.

  19. Survival of alpha particle irradiated cells as a function of the shape and size of the sensitive volume (nucleus)

    International Nuclear Information System (INIS)

    Stinchcomb, T.G.; Roeske, J.C.

    1995-01-01

    Microdosimetry is the study of the stochastic variation of energy deposited within sub-cellular targets. As such, the size and shape of the critical target (i.e. cell nucleus) are essential when considering microdosimetric quantities. In this work, a microdosimetric analysis examines the expected cell survival as a function of the size and shape of the cell nucleus under conditions of irradiation emitting alpha particles. The results indicate that, in general, cell survival is relatively insensitive to changes in the shape of the cell nucleus when the volume is held constant. However, cell survival is a strong function of the variation in the size of the target. These results are useful when analysing the results of cell survival experiments for alpha particle emitters. (Author)

  20. Effects of WC Particle Size and Co Content on the Graded Structure in Functionally Gradient WC-Co Composites

    Directory of Open Access Journals (Sweden)

    Yuan Yigao

    2016-01-01

    Full Text Available Functionally gradient WC-Co composites having a Co depleted surface zone and not comprising the h phase can be manufactured via carburizing process. During carburizing, besides carburizing process parameters, the microstructural parameters of WC-Co materials, such as WC grain size and Co content, also have significant influences on the formation of Co gradient structure. In this study, the effects of WC particle size and Co content on the gradient structure within gradient hardmetals have been studied, based on a series of carburizing experiments of WC-Co materials with different WC particle sizes and cobalt contents. The results show that both the thickness and the amplitude of the gradients within gradient WC-Co materials increase with increasing initial WC particle size and Co content of WC-Co alloys. The reason for this finding is discussed.

  1. Determination of plasma frequency, damping constant, and size distribution from the complex dielectric function of noble metal nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza Herrera, Luis J.; Arboleda, David Muñetón [Centro de Investigaciones Ópticas (CIOp), (CONICET La Plata-CIC) (Argentina); Schinca, Daniel C.; Scaffardi, Lucía B., E-mail: lucias@ciop.unlp.edu.ar [Centro de Investigaciones Ópticas (CIOp), (CONICET La Plata-CIC) (Argentina); Departamento de Ciencias Básicas, Facultad de Ingeniería, UNLP (Argentina)

    2014-12-21

    This paper develops a novel method for simultaneously determining the plasma frequency ω{sub P}   and the damping constant γ{sub free} in the bulk damped oscillator Drude model, based on experimentally measured real and imaginary parts of the metal refractive index in the IR wavelength range, lifting the usual approximation that restricts frequency values to the UV-deep UV region. Our method was applied to gold, silver, and copper, improving the relative uncertainties in the final values for ω{sub p} (0.5%–1.6%) and for γ{sub free} (3%–8%), which are smaller than those reported in the literature. These small uncertainties in ω{sub p} and γ{sub free} determination yield a much better fit of the experimental complex dielectric function. For the case of nanoparticles (Nps), a series expansion of the Drude expression (which includes ω{sub p} and γ{sub free} determined using our method) enables size-dependent dielectric function to be written as the sum of three terms: the experimental bulk dielectric function plus two size corrective terms, one for free electron, and the other for bound-electron contributions. Finally, size distribution of nanometric and subnanometric gold Nps in colloidal suspension was determined through fitting its experimental optical extinction spectrum using Mie theory based on the previously determined dielectric function. Results are compared with size histogram obtained from Transmission Electron Microscopy (TEM)

  2. Turbulent Concentration of MM-Size Particles in the Protoplanetary Nebula: Scaled-Dependent Multiplier Functions

    Science.gov (United States)

    Cuzzi, Jeffrey N.; Hartlep, Thomas; Weston, B.; Estremera, Shariff Kareem

    2014-01-01

    The initial accretion of primitive bodies (asteroids and TNOs) from freely-floating nebula particles remains problematic. Here we focus on the asteroids where constituent particle (read "chondrule") sizes are observationally known; similar arguments will hold for TNOs, but the constituent particles in those regions will be smaller, or will be fluffy aggregates, and are unobserved. Traditional growth-bysticking models encounter a formidable "meter-size barrier" [1] (or even a mm-cm-size barrier [2]) in turbulent nebulae, while nonturbulent nebulae form large asteroids too quickly to explain long spreads in formation times, or the dearth of melted asteroids [3]. Even if growth by sticking could somehow breach the meter size barrier, other obstacles are encountered through the 1-10km size range [4]. Another clue regarding planetesimal formation is an apparent 100km diameter peak in the pre-depletion, pre-erosion mass distribution of asteroids [5]; scenarios leading directly from independent nebula particulates to this size, which avoid the problematic m-km size range, could be called "leapfrog" scenarios [6-8]. The leapfrog scenario we have studied in detail involves formation of dense clumps of aerodynamically selected, typically mm-size particles in turbulence, which can under certain conditions shrink inexorably on 100-1000 orbit timescales and form 10-100km diameter sandpile planetesimals. The typical sizes of planetesimals and the rate of their formation [7,8] are determined by a statistical model with properties inferred from large numerical simulations of turbulence [9]. Nebula turbulence can be described by its Reynolds number Re = L/eta sup(4/3), where L = ETA alpha sup (1/2) the largest eddy scale, H is the nebula gas vertical scale height, and a the nebula turbulent viscosity parameter, and ? is the Kolmogorov or smallest scale in turbulence (typically about 1km), with eddy turnover time t?. In the nebula, Re is far larger than any numerical simulation can

  3. The human myotendinous junction

    DEFF Research Database (Denmark)

    Knudsen, A B; Larsen, M; Mackey, Abigail

    2015-01-01

    The myotendinous junction (MTJ) is a specialized structure in the musculotendinous system, where force is transmitted from muscle to tendon. Animal models have shown that the MTJ takes form of tendon finger-like processes merging with muscle tissue. The human MTJ is largely unknown and has never...... been described in three dimensions (3D). The aim of this study was to describe the ultrastructure of the human MTJ and render 3D reconstructions. Fourteen subjects (age 25 ± 3 years) with isolated injury of the anterior cruciate ligament (ACL), scheduled for reconstruction with a semitendinosus...

  4. SMALL AND MIDDLE-SIZED BUSINESS: LOGISTICAL AND SOCIAL AND ECONOMICAL FUNCTIONS

    Directory of Open Access Journals (Sweden)

    O. N. Pavlova

    2007-01-01

    Full Text Available Entrepreneurship is one of the factors that can ensure a sustainable character to the development of Belarus. The present Belarusian entrepreneurship should select the required forms and determine development priorities. It is practically impossible to do it without taking into account modem global social and economical tendencies and also specificity of Belarusian mentality and traditions. In this sense priority status is given to small and middle-sized business because it is considered as an element of economic system that ensures stability to economy. Small and middle-sized business is an ideal logistical model that provides harmonization of interests and optimization of management solutions.

  5. Gap junctions and motor behavior

    DEFF Research Database (Denmark)

    Kiehn, Ole; Tresch, Matthew C.

    2002-01-01

    The production of any motor behavior requires coordinated activity in motor neurons and premotor networks. In vertebrates, this coordination is often assumed to take place through chemical synapses. Here we review recent data suggesting that electrical gap-junction coupling plays an important role...... in coordinating and generating motor outputs in embryonic and early postnatal life. Considering the recent demonstration of a prevalent expression of gap-junction proteins and gap-junction structures in the adult mammalian spinal cord, we suggest that neuronal gap-junction coupling might also contribute...... to the production of motor behavior in adult mammals....

  6. Size-based emphysema cluster analysis on low attenuation area in 3D volumetric CT: comparison with pulmonary functional test

    Science.gov (United States)

    Lee, Minho; Kim, Namkug; Lee, Sang Min; Seo, Joon Beom; Oh, Sang Young

    2015-03-01

    To quantify low attenuation area (LAA) of emphysematous regions according to cluster size in 3D volumetric CT data of chronic obstructive pulmonary disease (COPD) patients and to compare these indices with their pulmonary functional test (PFT). Sixty patients with COPD were scanned by a more than 16-multi detector row CT scanner (Siemens Sensation 16 and 64) within 0.75mm collimation. Based on these LAA masks, a length scale analysis to estimate each emphysema LAA's size was performed as follows. At first, Gaussian low pass filter from 30mm to 1mm kernel size with 1mm interval on the mask was performed from large to small size, iteratively. Centroid voxels resistant to the each filter were selected and dilated by the size of the kernel, which was regarded as the specific size emphysema mask. The slopes of area and number of size based LAA (slope of semi-log plot) were analyzed and compared with PFT. PFT parameters including DLco, FEV1, and FEV1/FVC were significantly (all p-value< 0.002) correlated with the slopes (r-values; -0.73, 0.54, 0.69, respectively) and EI (r-values; -0.84, -0.60, -0.68, respectively). In addition, the D independently contributed regression for FEV1 and FEV1/FVC (adjust R sq. of regression study: EI only, 0.70, 0.45; EI and D, 0.71, 0.51, respectively). By the size based LAA segmentation and analysis, we evaluated the Ds of area, number, and distribution of size based LAA, which would be independent factors for predictor of PFT parameters.

  7. Sustained inhibition of rat myometrial gap junctions and contractions by lindane

    Directory of Open Access Journals (Sweden)

    Grindatti Carmen M

    2003-10-01

    Full Text Available Abstract Background Gap junctions increase in size and abundance coincident with parturition, forming an intercellular communication network that permits the uterus to develop the forceful, coordinated contractions necessary for delivery of the fetus. Lindane, a pesticide used in the human and veterinary treatment of scabies and lice as well as in agricultural applications, inhibits uterine contractions in vitro, inhibits myometrial gap junctions, and has been associated with prolonged gestation length in rats. The aim of the present study was to investigate whether brief exposures to lindane would elicit sustained inhibition of rat uterine contractile activity and myometrial gap junction intercellular communication. Methods To examine effects on uterine contraction, longitudinal uterine strips isolated from late gestation (day 20 rats were exposed to lindane in muscle baths and monitored for changes in spontaneous phasic contractions during and after exposure to lindane. Lucifer yellow dye transfer between myometrial cells in culture was used to monitor gap junction intercellular communication. Results During a 1-h exposure, 10 micro M and 100 micro M lindane decreased peak force and frequency of uterine contraction but 1 micro M lindane did not. After removal of the exposure buffer, contraction force remained significantly depressed in uterine strips exposed to 100 micro M lindane, returning to less than 50% basal levels 5 h after cessation of lindane exposure. In cultured myometrial myocytes, significant sustained inhibition of Lucifer yellow dye transfer was observed 24 h after lindane exposures as brief as 10 min and as low as 0.1 micro M lindane. Conclusion Brief in vitro exposures to lindane have long-term effects on myometrial functions that are necessary for parturition, inhibiting spontaneous phasic contractions in late gestation rat uterus and gap junction intercellular communication in myometrial cell cultures.

  8. Pricing via functional size : A case study of 77 outsourced projects

    NARCIS (Netherlands)

    Huijgens, H.; Gousios, G.; Van Deursen, A.

    2014-01-01

    A medium-sized west-European telecom company experienced a worsening trend in performance, indicating that the organization did not learn from history, in combination with much time and energy spent on preparation and review of project proposals. In order to create more transparency in the supplier

  9. SIZE DISTRIBUTION OF SEA-SALT EMISSIONS AS A FUNCTION OF RELATIVE HUMIDITY

    Science.gov (United States)

    This note presents a straightforward method to correct sea-salt-emission particle-size distributions according to local relative humidity. The proposed method covers a wide range of relative humidity (0.45 to 0.99) and its derivation incorporates recent laboratory results on sea-...

  10. Neutron generators with size scalability, ease of fabrication and multiple ion source functionalities

    Science.gov (United States)

    Elizondo-Decanini, Juan M

    2014-11-18

    A neutron generator is provided with a flat, rectilinear geometry and surface mounted metallizations. This construction provides scalability and ease of fabrication, and permits multiple ion source functionalities.

  11. Holographic s-wave and p-wave Josephson junction with backreaction

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yong-Qiang; Liu, Shuai [Institute of Theoretical Physics, Lanzhou University,Lanzhou 730000, People’s Republic of (China)

    2016-11-22

    In this paper, we study the holographic models of s-wave and p-wave Josephoson junction away from probe limit in (3+1)-dimensional spacetime, respectively. With the backreaction of the matter, we obtained the anisotropic black hole solution with the condensation of matter fields. We observe that the critical temperature of Josephoson junction decreases with increasing backreaction. In addition to this, the tunneling current and condenstion of Josephoson junction become smaller as backreaction grows larger, but the relationship between current and phase difference still holds for sine function. Moreover, condenstion of Josephoson junction deceases with increasing width of junction exponentially.

  12. Internal resonances in periodically modulated long Josephson junctions

    DEFF Research Database (Denmark)

    Larsen, Britt Hvolbæk; Mygind, Jesper; Ustinov, Alexey V.

    1995-01-01

    Current-voltage (I-V) characteristics of long Josephson junctions with a periodic lattice of localized inhomogeneities are studied. The interaction between the moving fluxons and the inhomogeneities causes resonant steps in the IV-curve. Some of these steps are due to a synchronization to resonant...... Fiske modes in the sub-junctions formed between the inhomogeneities. The voltage positions of the resonant steps oscillate as function of the applied magnetic field with a period corresponding to the inclusion of one magnetic flux quantum, Φ0=h/2e, per sub-junction. A qualitative explanation that takes...

  13. Steady-state properties of Josephson junctions with direct conductivity

    International Nuclear Information System (INIS)

    Zubkov, A.A.; Kupriyanov, M.Y.; Semenov, V.K.

    1981-01-01

    A new criterion for determining the kinetic inductance of Josephson junctions is introduced. The effects of temperature T, the critical temperatures of the superconducting electrodes T/sub c/1 and T/sub c/2, and the weak-link length on the kinetic inductance of ''dirty'' junctions with direct conductivity are analyzed within the framework of the Usadel equations. Numerical calculations show that both a large characteristic voltage and a nearly harmonic dependence of the current on the phase difference of the superconducting-electrode wave functions cannot be obtained by varying the junction parameters

  14. Ischemic preconditioning protects against gap junctional uncoupling in cardiac myofibroblasts.

    Science.gov (United States)

    Sundset, Rune; Cooper, Marie; Mikalsen, Svein-Ole; Ytrehus, Kirsti

    2004-01-01

    Ischemic preconditioning increases the heart's tolerance to a subsequent longer ischemic period. The purpose of this study was to investigate the role of gap junction communication in simulated preconditioning in cultured neonatal rat cardiac myofibroblasts. Gap junctional intercellular communication was assessed by Lucifer yellow dye transfer. Preconditioning preserved intercellular coupling after prolonged ischemia. An initial reduction in coupling in response to the preconditioning stimulus was also observed. This may protect neighboring cells from damaging substances produced during subsequent regional ischemia in vivo, and may preserve gap junctional communication required for enhanced functional recovery during subsequent reperfusion.

  15. Superconducting proximity effect in mesoscopic superconductor/normal-metal junctions

    CERN Document Server

    Takayanagi, H; Toyoda, E

    1999-01-01

    The superconducting proximity effect is discussed in mesoscopic superconductor/normal-metal junctions. The newly-developed theory shows long-range phase-coherent effect which explaines early experimental results of giant magnetoresistance oscillations in an Andreev interferometer. The theory also shows that the proximity correction to the conductance (PCC) has a reentrant behavior as a function of energy. The reentrant behavior is systematically studied in a gated superconductor-semiconductor junction. A negative PCC is observed in the case of a weak coupling between the normal metal and the external reservoir. Phase coherent ac effect is also observed when rf is irradiated to the junction.

  16. Effects of loading sequences and size of repeated stress block of loads on fatigue life calculated using fatigue functions

    International Nuclear Information System (INIS)

    Schott, G.

    1989-01-01

    It is well-known that collective form, stress intensity and loading sequence of individual stresses as well as size of repeated stress blocks can influence fatigue life, significantly. The basic variant of the consecutive Woehler curve concept will permit these effects to be involved into fatigue life computation. The paper presented will demonstrate that fatigue life computations using fatigue functions reflect the loading sequence effect with multilevel loading precisely and provide reliable fatigue life data. Effects of size of repeated stress block and loading sequence on fatigue life as observed with block program tests can be reproduced using the new computation method. (orig.) [de

  17. Electron transport in doped fullerene molecular junctions

    Science.gov (United States)

    Kaur, Milanpreet; Sawhney, Ravinder Singh; Engles, Derick

    The effect of doping on the electron transport of molecular junctions is analyzed in this paper. The doped fullerene molecules are stringed to two semi-infinite gold electrodes and analyzed at equilibrium and nonequilibrium conditions of these device configurations. The contemplation is done using nonequilibrium Green’s function (NEGF)-density functional theory (DFT) to evaluate its density of states (DOS), transmission coefficient, molecular orbitals, electron density, charge transfer, current, and conductance. We conclude from the elucidated results that Au-C16Li4-Au and Au-C16Ne4-Au devices behave as an ordinary p-n junction diode and a Zener diode, respectively. Moreover, these doped fullerene molecules do not lose their metallic nature when sandwiched between the pair of gold electrodes.

  18. Non-Lagrangian theories from brane junctions

    Energy Technology Data Exchange (ETDEWEB)

    Bao, Ling [Chalmers Univ. of Technology, Goeteborg (Sweden); Mitev, Vladimir [Humboldt Univ., Berlin (Germany). Inst. fuer Mathematik und Inst. fuer Physik; Pomoni, Elli [Deutsches Elektronen-Synchrotron DESY, Hamburg (Germany). Theory Group; Taki, Masato [RIKEN Nishina Center, Saitama (Japan). Mathematical Physics Lab.; Yagi, Futoshi [International School of Advanced Studies (SISSA), Trieste (Italy); INFN, Trieste (Italy); Korea Institute for Advanced Study (KIAS), Seoul (Korea, Republic of)

    2013-10-15

    In this article we use 5-brane junctions to study the 5D T{sub N} SCFTs corresponding to the 5D N=1 uplift of the 4D N=2 strongly coupled gauge theories, which are obtained by compactifying N M5 branes on a sphere with three full punctures. Even though these theories have no Lagrangian description, by using the 5-brane junctions proposed by Benini, Benvenuti and Tachikawa, we are able to derive their Seiberg-Witten curves and Nekrasov partition functions. We cross-check our results with the 5D superconformal index proposed by Kim, Kim and Lee. Through the AGTW correspondence, we discuss the relations between 5D superconformal indices and n-point functions of the q-deformed W{sub N} Toda theories.

  19. Non-Lagrangian theories from brane junctions

    International Nuclear Information System (INIS)

    Bao, Ling; Mitev, Vladimir

    2013-10-01

    In this article we use 5-brane junctions to study the 5D T N SCFTs corresponding to the 5D N=1 uplift of the 4D N=2 strongly coupled gauge theories, which are obtained by compactifying N M5 branes on a sphere with three full punctures. Even though these theories have no Lagrangian description, by using the 5-brane junctions proposed by Benini, Benvenuti and Tachikawa, we are able to derive their Seiberg-Witten curves and Nekrasov partition functions. We cross-check our results with the 5D superconformal index proposed by Kim, Kim and Lee. Through the AGTW correspondence, we discuss the relations between 5D superconformal indices and n-point functions of the q-deformed W N Toda theories.

  20. High Affinity, Developability and Functional Size: The Holy Grail of Combinatorial Antibody Library Generation

    Directory of Open Access Journals (Sweden)

    Kathrin Tissot

    2011-05-01

    Full Text Available Since the initial description of phage display technology for the generation of human antibodies, a variety of selection methods has been developed. The most critical parameter for all in vitro-based approaches is the quality of the antibody library. Concurrent evolution of the libraries has allowed display and selection technologies to reveal their full potential. They come in different flavors, from naïve to fully synthetic and differ in terms of size, quality, method of preparation, framework and CDR composition. Early on, the focus has mainly been on affinities and thus on library size and diversity. Subsequently, the increased awareness of developability and cost of goods as important success factors has spurred efforts to generate libraries with improved biophysical properties and favorable production characteristics. More recently a major focus on reduction of unwanted side effects through reduced immunogenicity and improved overall biophysical behavior has led to a re-evaluation of library design.

  1. Distribution Functions of Sizes and Fluxes Determined from Supra-Arcade Downflows

    Science.gov (United States)

    McKenzie, D.; Savage, S.

    2011-01-01

    The frequency distributions of sizes and fluxes of supra-arcade downflows (SADs) provide information about the process of their creation. For example, a fractal creation process may be expected to yield a power-law distribution of sizes and/or fluxes. We examine 120 cross-sectional areas and magnetic flux estimates found by Savage & McKenzie for SADs, and find that (1) the areas are consistent with a log-normal distribution and (2) the fluxes are consistent with both a log-normal and an exponential distribution. Neither set of measurements is compatible with a power-law distribution nor a normal distribution. As a demonstration of the applicability of these findings to improved understanding of reconnection, we consider a simple SAD growth scenario with minimal assumptions, capable of producing a log-normal distribution.

  2. Quantitative size-dependent structure and strain determination of CdSe nanoparticles using atomic pair distribution function analysis

    Energy Technology Data Exchange (ETDEWEB)

    Masadeh, A S; Bozin, E S; Farrow, C L; Paglia, G; Juhas, P; Billinge, S J. L.; Karkamkar, A; Kanatzidis, M G [Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-1116 (United States); Department of Chemistry, Michigan State University, East Lansing, Michigan 48824-1116 (United States)

    2007-09-15

    The size-dependent structure of CdSe nanoparticles, with diameters ranging from 2 to 4 nm, has been studied using the atomic pair distribution function (PDF) method. The core structure of the measured CdSe nanoparticles can be described in terms of the wurtzite atomic structure with extensive stacking faults. The density of faults in the nanoparticles is {approx}50%. The diameter of the core region was extracted directly from the PDF data and is in good agreement with the diameter obtained from standard characterization methods, suggesting that there is little surface amorphous region. A compressive strain was measured in the Cd-Se bond length that increases with decreasing particle size being 0.5% with respect to bulk CdSe for the 2 nm diameter particles. This study demonstrates the size-dependent quantitative structural information that can be obtained even from very small nanoparticles using the PDF approach.

  3. Junction detection and pathway selection

    Science.gov (United States)

    Peck, Alex N.; Lim, Willie Y.; Breul, Harry T.

    1992-02-01

    The ability to detect junctions and make choices among the possible pathways is important for autonomous navigation. In our script-based navigation approach where a journey is specified as a script of high-level instructions, actions are frequently referenced to junctions, e.g., `turn left at the intersection.' In order for the robot to carry out these kind of instructions, it must be able (1) to detect an intersection (i.e., an intersection of pathways), (2) know that there are several possible pathways it can take, and (3) pick the pathway consistent with the high level instruction. In this paper we describe our implementation of the ability to detect junctions in an indoor environment, such as corners, T-junctions and intersections, using sonar. Our approach uses a combination of partial scan of the local environment and recognition of sonar signatures of certain features of the junctions. In the case where the environment is known, we use additional sensor information (such as compass bearings) to help recognize the specific junction. In general, once a junction is detected and its type known, the number of possible pathways can be deduced and the correct pathway selected. Then the appropriate behavior for negotiating the junction is activated.

  4. Mixing in T-junctions

    NARCIS (Netherlands)

    Kok, Jacobus B.W.; van der Wal, S.

    1996-01-01

    The transport processes that are involved in the mixing of two gases in a T-junction mixer are investigated. The turbulent flow field is calculated for the T-junction with the k- turbulence model by FLOW3D. In the mathematical model the transport of species is described with a mixture fraction

  5. Dynamics of Josephson junction arrays

    International Nuclear Information System (INIS)

    Hadley, P.

    1989-01-01

    The dynamics of Josephson junction arrays is a topic that lies at the intersection of the fields of nonlinear dynamics and Josephson junction technology. The series arrays considered here consist of several rapidly oscillating Josephson junctions where each junction is coupled equally to every other junction. The purpose of this study is to understand phaselocking and other cooperative dynamics of this system. Previously, little was known about high dimensional nonlinear systems of this sort. Numerical simulations are used to study the dynamics of these arrays. Three distinct types of periodic solutions to the array equations were observed as well as period doubled and chaotic solutions. One of the periodic solutions is the symmetric, in-phase solution where all of the junctions oscillate identically. The other two periodic solutions are symmetry-broken solutions where all of the junction do not oscillate identically. The symmetry-broken solutions are highly degenerate. As many as (N - 1) stable solutions can coexist for an array of N junctions. Understanding the stability of these several solutions and the transitions among them is vital to the design of useful devices

  6. Finite-size scaling functions for directed polymers confined between attracting walls

    Energy Technology Data Exchange (ETDEWEB)

    Owczarek, A L [Department of Mathematics and Statistics, University of Melbourne, Parkville, Victoria 3052 (Australia); Prellberg, T [School of Mathematical Sciences, Queen Mary, University of London, Mile End Road, London E1 4NS (United Kingdom); Rechnitzer, A [Department of Mathematics, University of British Columbia, Vancouver, BC V6T 1Z2 (Canada)

    2008-01-25

    The exact solution of directed self-avoiding walks confined to a slit of finite width and interacting with the walls of the slit via an attractive potential has been recently calculated. The walks can be considered to model the polymer-induced steric stabilization and sensitized flocculation of colloidal dispersions. The large-width asymptotics led to a phase diagram different to that of a polymer attached to, and attracted to, a single wall. The question that arises is: Can one interpolate between the single wall and two wall cases? In this paper, we calculate the exact scaling functions for the partition function by considering the two variable asymptotics of the partition function for simultaneous large length and large width. Consequently, we find the scaling functions for the force induced by the polymer on the walls. We find that these scaling functions are given by elliptic {theta} functions. In some parts of the phase diagram there is more a complex crossover between the single wall and two wall cases and we elucidate how this happens.

  7. A two-level parallel direct search implementation for arbitrarily sized objective functions

    Energy Technology Data Exchange (ETDEWEB)

    Hutchinson, S.A.; Shadid, N.; Moffat, H.K. [Sandia National Labs., Albuquerque, NM (United States)] [and others

    1994-12-31

    In the past, many optimization schemes for massively parallel computers have attempted to achieve parallel efficiency using one of two methods. In the case of large and expensive objective function calculations, the optimization itself may be run in serial and the objective function calculations parallelized. In contrast, if the objective function calculations are relatively inexpensive and can be performed on a single processor, then the actual optimization routine itself may be parallelized. In this paper, a scheme based upon the Parallel Direct Search (PDS) technique is presented which allows the objective function calculations to be done on an arbitrarily large number (p{sub 2}) of processors. If, p, the number of processors available, is greater than or equal to 2p{sub 2} then the optimization may be parallelized as well. This allows for efficient use of computational resources since the objective function calculations can be performed on the number of processors that allow for peak parallel efficiency and then further speedup may be achieved by parallelizing the optimization. Results are presented for an optimization problem which involves the solution of a PDE using a finite-element algorithm as part of the objective function calculation. The optimum number of processors for the finite-element calculations is less than p/2. Thus, the PDS method is also parallelized. Performance comparisons are given for a nCUBE 2 implementation.

  8. UTP reduces infarct size and improves mice heart function after myocardial infarct via P2Y2 receptor

    DEFF Research Database (Denmark)

    Cohen, A; Shainberg, Asher; Hochhauser, E

    2011-01-01

    Pyrimidine nucleotides are signaling molecules, which activate G protein-coupled membrane receptors of the P2Y family. P2Y(2) and P2Y(4) receptors are part of the P2Y family, which is composed of 8 subtypes that have been cloned and functionally defined. We have previously found that uridine-5......'-triphosphate (UTP) reduces infarct size and improves cardiac function following myocardial infarct (MI). The aim of the present study was to determine the role of P2Y(2) receptor in cardiac protection following MI using knockout (KO) mice, in vivo and wild type (WT) for controls. In both experimental groups...... used (WT and P2Y(2)(-/-) receptor KO mice) there were 3 subgroups: sham, MI, and MI+UTP. 24h post MI we performed echocardiography and measured infarct size using triphenyl tetrazolium chloride (TTC) staining on all mice. Fractional shortening (FS) was higher in WT UTP-treated mice than the MI group...

  9. Beyond the rhizosphere: growth and function of arbuscular mycorrhizal external hyphae in sands of varying pore sizes

    DEFF Research Database (Denmark)

    Drew, E.A.; Murray, R.S.; Smith, S.E.

    2003-01-01

    Research on nutrient acquisition by symbiotic arbuscular mycorrhizal (AM) fungi has mainly focused on the root fungus interface and less attention has been given to the growth and functioning of external hyphae in the bulk soil. The growth and function of external hyphae may be affected....... intraradices obtained a greater proportion of P at a distance from the host roots. Differences in P acquisition were not correlated with production of external hyphae in the four media zones and changes in sand pore size did not affect the ability of the fungi studied to acquire P at a distance from the host...... roots. Production of external hyphae in HC2 was influenced by fungal species and media treatment. Both fungi produced maximum amounts of external hyphae in the soil medium. Sand pore size affected growth of G. intraradices (but not G. mosseae) and hyphal diameter distributions of both fungi. The results...

  10. Genetic ablation of soluble TNF does not affect lesion size and functional recovery after moderate spinal cord injury in mice

    DEFF Research Database (Denmark)

    Ellman, Ditte Gry; Degn, Matilda; Lund, Minna Christiansen

    2016-01-01

    Traumatic spinal cord injury (SCI) is followed by an instant increase in expression of the microglial-derived proinflammatory cytokine tumor necrosis factor (TNF) within the lesioned cord. TNF exists both as membrane-anchored TNF (mTNF) and as cleaved soluble TNF (solTNF). We previously demonstra......, and MHCII), lesion size, and functional outcome after moderate SCI were comparable between genotypes. Collectively, our data demonstrate that genetic ablation of solTNF does not significantly modulate postlesion outcome after SCI....

  11. Analysis of point source size on measurement accuracy of lateral point-spread function of confocal Raman microscopy

    Science.gov (United States)

    Fu, Shihang; Zhang, Li; Hu, Yao; Ding, Xiang

    2018-01-01

    Confocal Raman Microscopy (CRM) has matured to become one of the most powerful instruments in analytical science because of its molecular sensitivity and high spatial resolution. Compared with conventional Raman Microscopy, CRM can perform three dimensions mapping of tiny samples and has the advantage of high spatial resolution thanking to the unique pinhole. With the wide application of the instrument, there is a growing requirement for the evaluation of the imaging performance of the system. Point-spread function (PSF) is an important approach to the evaluation of imaging capability of an optical instrument. Among a variety of measurement methods of PSF, the point source method has been widely used because it is easy to operate and the measurement results are approximate to the true PSF. In the point source method, the point source size has a significant impact on the final measurement accuracy. In this paper, the influence of the point source sizes on the measurement accuracy of PSF is analyzed and verified experimentally. A theoretical model of the lateral PSF for CRM is established and the effect of point source size on full-width at half maximum of lateral PSF is simulated. For long-term preservation and measurement convenience, PSF measurement phantom using polydimethylsiloxane resin, doped with different sizes of polystyrene microspheres is designed. The PSF of CRM with different sizes of microspheres are measured and the results are compared with the simulation results. The results provide a guide for measuring the PSF of the CRM.

  12. Genetic differentiation for size at first reproduction through male versus female functions in the widespread Mediterranean tree Pinus pinaster.

    Science.gov (United States)

    Santos-del-Blanco, L; Climent, J; González-Martínez, S C; Pannell, J R

    2012-11-01

    The study of local adaptation in plant reproductive traits has received substantial attention in short-lived species, but studies conducted on forest trees are scarce. This lack of research on long-lived species represents an important gap in our knowledge, because inferences about selection on the reproduction and life history of short-lived species cannot necessarily be extrapolated to trees. This study considers whether the size for first reproduction is locally adapted across a broad geographical range of the Mediterranean conifer species Pinus pinaster. In particular, the study investigates whether this monoecious species varies genetically among populations in terms of whether individuals start to reproduce through their male function, their female function or both sexual functions simultaneously. Whether differences among populations could be attributed to local adaptation across a climatic gradient is then considered. Male and female reproduction and growth were measured during early stages of sexual maturity of a P. pinaster common garden comprising 23 populations sampled across the species range. Generalized linear mixed models were used to assess genetic variability of early reproductive life-history traits. Environmental correlations with reproductive life-history traits were tested after controlling for neutral genetic structure provided by 12 nuclear simple sequence repeat markers. Trees tended to reproduce first through their male function, at a size (height) that varied little among source populations. The transition to female reproduction was slower, showed higher levels of variability and was negatively correlated with vegetative growth traits. Several female reproductive traits were correlated with a gradient of growth conditions, even after accounting for neutral genetic structure, with populations from more unfavourable sites tending to commence female reproduction at a lower individual size. The study represents the first report of genetic

  13. Anisotropic Magnetoresistance and Anisotropic Tunneling Magnetoresistance due to Quantum Interference in Ferromagnetic Metal Break Junctions

    DEFF Research Database (Denmark)

    Bolotin, Kirill; Kuemmeth, Ferdinand; Ralph, D

    2006-01-01

    We measure the low-temperature resistance of permalloy break junctions as a function of contact size and the magnetic field angle in applied fields large enough to saturate the magnetization. For both nanometer-scale metallic contacts and tunneling devices we observe large changes in resistance w...... with the angle, as large as 25% in the tunneling regime. The pattern of magnetoresistance is sensitive to changes in bias on a scale of a few mV. We interpret the effect as a consequence of conductance fluctuations due to quantum interference....

  14. Functional groups and reactivity of size-fractionated Aldrich humic acid

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Tadao, E-mail: tanaka.tadao26@jaea.go.jp [Nuclear Safety Research Center, Japan Atomic Energy Agency, Shirakata 2-4, Tokai, Naka, Ibaraki, 319-1195 (Japan)

    2012-03-20

    The complexation affinity of the Aldrich Chemicals humic acid with {sup 60}Co was examined with respect to molecular size of humic acid. Correlations between the affinity and the structures of humic acid were studied. At low humic acid concentration range, {sup 60}Co was interacted with the humic acid of size fraction over 100k Da (HA(100<)). With increasing humic acid concentration, the {sup 60}Co was preferentially interacted with the 30k-100k Da of humic acid (HA(30-100)). Fractionated HA(100<) and HA(30-100) were characterized from their FTIR (Fourier Transform Infra-Red), {sup 13}C NMR spectral analyses and acid-base titration curves. The HA(10<) having aliphatic branched structure, smaller amount of COOH group and large proton exchangeable capacity, seem to show low covalent bonding nature and high ion exchangeability in the complexation. In addition, steric hindrance may affect on the complexation, by winding up like random coils from the branched structure. The HA(30-100) is dominated with the aromatic COOH group and OH group and it may preferentially coordinate to {sup 60}Co by covalent binding. These presumptions were supported by XPS analysis, in which the biding energy of cobalt-humates was discussed.

  15. Regulation of Tight Junctions in Upper Airway Epithelium

    Directory of Open Access Journals (Sweden)

    Takashi Kojima

    2013-01-01

    Full Text Available The mucosal barrier of the upper respiratory tract including the nasal cavity, which is the first site of exposure to inhaled antigens, plays an important role in host defense in terms of innate immunity and is regulated in large part by tight junctions of epithelial cells. Tight junction molecules are expressed in both M cells and dendritic cells as well as epithelial cells of upper airway. Various antigens are sampled, transported, and released to lymphocytes through the cells in nasal mucosa while they maintain the integrity of the barrier. Expression of tight junction molecules and the barrier function in normal human nasal epithelial cells (HNECs are affected by various stimuli including growth factor, TLR ligand, and cytokine. In addition, epithelial-derived thymic stromal lymphopoietin (TSLP, which is a master switch for allergic inflammatory diseases including allergic rhinitis, enhances the barrier function together with an increase of tight junction molecules in HNECs. Furthermore, respiratory syncytial virus infection in HNECs in vitro induces expression of tight junction molecules and the barrier function together with proinflammatory cytokine release. This paper summarizes the recent progress in our understanding of the regulation of tight junctions in the upper airway epithelium under normal, allergic, and RSV-infected conditions.

  16. Association diastolic function by echo and infarct size by magnetic resonance imaging after STEMI

    DEFF Research Database (Denmark)

    Søholm, Helle; Lønborg, Jacob; Andersen, Mads J

    2016-01-01

    OBJECTIVES: Left ventricular (LV) diastolic dysfunction is a predictor of increased morbidity and mortality; however, little is known about diastolic function and the degree of myocardial damage after myocardial infarction (MI). The aim was to assess the association between diastolic dysfunction ...

  17. A simulation study provided sample size guidance for differential item functioning (DIF) studies using short scales

    DEFF Research Database (Denmark)

    Scott, Neil W.; Fayers, Peter M.; Bottomley, Andrew

    2009-01-01

    Differential item functioning (DIF) analyses are increasingly used to evaluate health-related quality of life (HRQoL) instruments, which often include relatively short subscales. Computer simulations were used to explore how various factors including scale length affect analysis of DIF by ordinal...... logistic regression....

  18. A Meta-model for the Assessment of Non-Functional Requirement Size

    NARCIS (Netherlands)

    Kassab, M.; Daneva, Maia; Ormandjieva, O.; Mirandola, R.

    2008-01-01

    Non-functional requirements (NFRs) pose unique challenges in estimating the effort it would take to implement them. This is mainly because of their unique nature; NFRs are subjective, relative, interactive and tending to have a broad impact on the system as a whole. Nevertheless, it is crucial, when

  19. Prediction of spatially variable unsaturated hydraulic conductivity using scaled particle-size distribution functions

    NARCIS (Netherlands)

    Nasta, P.; Romano, N.; Assouline, S; Vrugt, J.A.; Hopmans, J.W.

    2013-01-01

    Simultaneous scaling of soil water retention and hydraulic conductivity functions provides an effective means to characterize the heterogeneity and spatial variability of soil hydraulic properties in a given study area. The statistical significance of this approach largely depends on the number of

  20. Effects of PEG size on structure, function and stability of PEGylated BSA

    DEFF Research Database (Denmark)

    Plesner, Bitten; Fee, Conan J.; Westh, Peter

    2011-01-01

    The effects of PEGylation on the structural, thermal and functional stability of bovine serum albumin (BSA) were investigated using BSA and 6 linear mono-PEGylated BSA compounds. The secondary and tertiary structure of BSA measured by circular dichroism (CD) was independent of PEGylation. In cont...

  1. On the functional form of particle number size distributions: influence of particle source and meteorological variables

    Science.gov (United States)

    Cugerone, Katia; De Michele, Carlo; Ghezzi, Antonio; Gianelle, Vorne; Gilardoni, Stefania

    2018-04-01

    Particle number size distributions (PNSDs) have been collected periodically in the urban area of Milan, Italy, during 2011 and 2012 in winter and summer months. Moreover, comparable PNSD measurements were carried out in the rural mountain site of Oga-San Colombano (2250 m a.s.l.), Italy, during February 2005 and August 2011. The aerosol data have been measured through the use of optical particle counters in the size range 0.3-25 µm, with a time resolution of 1 min. The comparison of the PNSDs collected in the two sites has been done in terms of total number concentration, showing higher numbers in Milan (often exceeding 103 cm-3 in winter season) compared to Oga-San Colombano (not greater than 2×102 cm-3), as expected. The skewness-kurtosis plane has been used in order to provide a synoptic view, and select the best distribution family describing the empirical PNSD pattern. The four-parameter Johnson system-bounded distribution (called Johnson SB or JSB) has been tested for this aim, due to its great flexibility and ability to assume different shapes. The PNSD pattern has been found to be generally invariant under site and season changes. Nevertheless, several PNSDs belonging to the Milan winter season (generally more than 30 %) clearly deviate from the standard empirical pattern. The seasonal increase in the concentration of primary aerosols due to combustion processes in winter and the influence of weather variables throughout the year, such as precipitation and wind speed, could be considered plausible explanations of PNSD dynamics.

  2. Distribution of trace elements in selected pulverized coals as a function of particle size and density

    Science.gov (United States)

    Senior, C.L.; Zeng, T.; Che, J.; Ames, M.R.; Sarofim, A.F.; Olmez, I.; Huggins, Frank E.; Shah, N.; Huffman, G.P.; Kolker, A.; Mroczkowski, S.; Palmer, C.; Finkelman, R.

    2000-01-01

    Trace elements in coal have diverse modes of occurrence that will greatly influence their behavior in many coal utilization processes. Mode of occurrence is important in determining the partitioning during coal cleaning by conventional processes, the susceptibility to oxidation upon exposure to air, as well as the changes in physical properties upon heating. In this study, three complementary methods were used to determine the concentrations and chemical states of trace elements in pulverized samples of four US coals: Pittsburgh, Illinois No. 6, Elkhorn and Hazard, and Wyodak coals. Neutron Activation Analysis (NAA) was used to measure the absolute concentration of elements in the parent coals and in the size- and density-fractionated samples. Chemical leaching and X-ray absorption fine structure (XAFS) spectroscopy were used to provide information on the form of occurrence of an element in the parent coals. The composition differences between size-segregated coal samples of different density mainly reflect the large density difference between minerals, especially pyrite, and the organic portion of the coal. The heavy density fractions are therefore enriched in pyrite and the elements associated with pyrite, as also shown by the leaching and XAFS methods. Nearly all the As is associated with pyrite in the three bituminous coals studied. The sub-bituminous coal has a very low content of pyrite and arsenic; in this coal arsenic appears to be primarily organically associated. Selenium is mainly associated with pyrite in the bituminous coal samples. In two bituminous coal samples, zinc is mostly in the form of ZnS or associated with pyrite, whereas it appears to be associated with other minerals in the other two coals. Zinc is also the only trace element studied that is significantly more concentrated in the smaller (45 to 63 ??m) coal particles.

  3. Functional implications of species differences in the size and morphology of the isthmo optic nucleus (ION in birds.

    Directory of Open Access Journals (Sweden)

    Cristián Gutiérrez-Ibáñez

    Full Text Available In birds, there is a retinofugal projection from the brain to the retina originating from the isthmo optic nucleus (ION in the midbrain. Despite a large number of anatomical, physiological and histochemical studies, the function of this retinofugal system remains unclear. Several functions have been proposed including: gaze stabilization, pecking behavior, dark adaptation, shifting attention, and detection of aerial predators. This nucleus varies in size and organization among some species, but the relative size and morphology of the ION has not been systematically studied. Here, we present a comparison of the relative size and morphology of the ION in 81 species of birds, representing 17 different orders. Our results show that several orders of birds, besides those previously reported, have a large, well-organized ION, including: hummingbirds, woodpeckers, coots and allies, and kingfishers. At the other end of the spectrum, parrots, herons, waterfowl, owls and diurnal raptors have relatively small ION volumes. ION also appears to be absent or unrecognizable is several taxa, including one of the basal avian groups, the tinamous, which suggests that the ION may have evolved only in the more modern group of birds, Neognathae. Finally, we demonstrate that evolutionary changes in the relative size and the cytoarchitectonic organization of ION have occurred largely independent of phylogeny. The large relative size of the ION in orders with very different lifestyles and feeding behaviors suggest there is no clear association with pecking behavior or predator detection. Instead, our results suggest that the ION is more complex and enlarged in birds that have eyes that are emmetropic in some parts of the visual field and myopic in others. We therefore posit that the ION is involved in switching attention between two parts of the retina i.e. from an emmetropic to a myopic part of the retina.

  4. Particle diffusional layer thickness in a USP dissolution apparatus II: a combined function of particle size and paddle speed.

    Science.gov (United States)

    Sheng, Jennifer J; Sirois, Paul J; Dressman, Jennifer B; Amidon, Gordon L

    2008-11-01

    This work was to investigate the effects of particle size and paddle speed on the particle diffusional layer thickness h(app) in a USP dissolution apparatus II. After the determination of the powder dissolution rates of five size fractions of fenofibrate, including <20, 20-32, 32-45, 63-75, and 90-106 microm, the present work shows that the dependence of h(app) on particle size follows different functions in accordance with the paddle speed. At 50 rpm, the function of h(app) is best described by a linear plot of h{app} = 9.91sqrt d-23.31 (R(2) = 0.98) throughout the particle diameter, d, from 6.8 to 106 microm. In contrast, at 100 rpm a transitional particle radius, r, of 23.7 microm exists, under which linear relationship h(app) = 1.59r (R(2) = 0.98) occurs, but above which h(app) becomes a constant of 43.5 microm. Thus, h(app) changes not only with particle size, but also with the hydrodynamics under standard USP configurations, which has been overlooked in the past. Further, the effects of particle size and paddle speed on h(app) were combined using dimensionless analysis. Within certain fluid velocity/particle regime, linear correlation of h(app)/d with the square-root of Reynolds number (d\\varpi/upsilon){1/2}, that is, h{app}/d = 1.5207 - 9.25 x 10{- 4} (d\\varpi/n){1/2} (R(2) = 0.9875), was observed.

  5. Breaking into the epithelial apical-junctional complex--news from pathogen hackers.

    Science.gov (United States)

    Vogelmann, Roger; Amieva, Manuel R; Falkow, Stanley; Nelson, W James

    2004-02-01

    The epithelial apical-junctional complex is a key regulator of cellular functions. In addition, it is an important target for microbial pathogens that manipulate the cell to survive, proliferate and sometimes persist within a host. Out of a myriad of potential molecular targets, some bacterial and viral pathogens have selected a subset of protein targets at the apical-junctional complex of epithelial cells. Studying how microbes use these targets also teaches us about the inherent physiological properties of host molecules in the context of normal junctional structure and function. Thus, we have learned that three recently uncovered components of the apical-junctional complex of the Ig superfamily--junctional adhesion molecule, Nectin and the coxsackievirus and adenovirus receptor--are important regulators of junction structure and function and represent critical targets of microbial virulence gene products.

  6. Breaking into the epithelial apical–junctional complex — news from pathogen hackers

    Science.gov (United States)

    Vogelmann, Roger; Amieva, Manuel R; Falkow, Stanley; Nelson, W James

    2012-01-01

    The epithelial apical–junctional complex is a key regulator of cellular functions. In addition, it is an important target for microbial pathogens that manipulate the cell to survive, proliferate and sometimes persist within a host. Out of a myriad of potential molecular targets, some bacterial and viral pathogens have selected a subset of protein targets at the apical–junctional complex of epithelial cells. Studying how microbes use these targets also teaches us about the inherent physiological properties of host molecules in the context of normal junctional structure and function. Thus, we have learned that three recently uncovered components of the apical–junctional complex of the Ig superfamily — junctional adhesion molecule, Nectin and the coxsackievirus and adenovirus receptor — are important regulators of junction structure and function and represent critical targets of microbial virulence gene products. PMID:15037310

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

    International Nuclear Information System (INIS)

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

    1990-01-01

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

  8. Characteristics Of Basaltic Sand: Size, Shape, And Composition As A Function Of Transport Process And Distance

    Science.gov (United States)

    Craddock, R. A.; Needell, Z. A.; Rose, T. R.

    2012-04-01

    Overview: The chemical and physical characteristics of sedimentary material can provide valuable clues about transport processes, distance traveled, and provenance, all of which are aspects of Martian geography that we would like to better understand. For a typical sedimentary deposit on Earth, for example, it has been shown that the ratio of feldspar to quartz can be used to assess the maturity (or transport distance) of a terrestrial deposit, because feldspar is more vulnerable to weathering than quartz. Further, chemical analysis can also be used to determine potential sediment sources, and grain-size sorting can be used to distinguish aeolian sediments (typically well-sorted) from fluvial sediments (poorly sorted in high energy environments). It is also common to use the shapes of individual quartz particles to determine transport process and distance, all of which can help us better understand the history of a sample of sedimentary material and the geological processes that created and emplaced it. These traditional sedimentological concepts are now being applied to our interpretation of Martian surface materials. Sullivan et al. [2008], for example, used grain-size and shape to assess eolian processes and to qualify transport distances of deposits found at the Spirit landing site in Gusev Crater. Stockstill-Cahill et al. [62008 used variations in mineral abundances observed in multispectral data to determine the provenance of dark dunes found in Amazonis Planitia craters. While applying our understanding of terrestrial sedimentary materials to Martian surface materials is intuitively sound and logical, the problem is that most of our current understanding is based on sediments derived from felsic materials (e.g., granite) primarily because that is the composition of most of the landmass on the Earth. However, the Martian surface is composed primarily of mafic material, or basalt, which generates much different sedimentary particles as it weathers. Instead of

  9. Plasma hydrogenated cationic detonation nanodiamonds efficiently deliver to human cells in culture functional siRNA targeting the Ewing sarcoma junction oncogene.

    Science.gov (United States)

    Bertrand, Jean-Rémi; Pioche-Durieu, Catherine; Ayala, Juan; Petit, Tristan; Girard, Hugues A; Malvy, Claude P; Le Cam, Eric; Treussart, François; Arnault, Jean-Charles

    2015-03-01

    The expression of a defective gene can lead to major cell dysfunctions among which cell proliferation and tumor formation. One promising therapeutic strategy consists in silencing the defective gene using small interfering RNA (siRNA). In previous publications we showed that diamond nanocrystals (ND) of primary size 35 nm, rendered cationic by polyethyleneimine-coating, can efficiently deliver siRNA into cell, which further block the expression of EWS/FLI-1 oncogene in a Ewing sarcoma disease model. However, a therapeutic application of such nanodiamonds requires their elimination by the organism, particularly in urine, which is impossible for 35 nm particles. Here, we report that hydrogenated cationic nanodiamonds of primary size 7 nm (ND-H) have also a high affinity for siRNA and are capable of delivering them in cells. With siRNA/ND-H complexes, we measured a high inhibition efficacy of EWS/FLI-1 gene expression in Ewing sarcoma cell line. Electron microscopy investigations showed ND-H in endocytosis compartments, and especially in macropinosomes from which they can escape before siRNA degradation occurred. In addition, the association of EWS/FLI-1 silencing by the siRNA/ND-H complex with a vincristine treatment yielded a potentiation of the toxic effect of this chemotherapeutic drug. Therefore ND-H appears as a promising delivery agent in anti-tumoral gene therapy. Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Ultrasonographic evaluation of Hashimoto's thyroiditis: Comparison of size and echo change with thyroid function

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Kang Rae; Cho, Jae Hyun; Kim, Yun Jeong; Kim, Hyun Man; Park, Rae Woong; Suh, Jung Ho [Aju University School of Medicine, Suwon (Korea, Republic of); Kang, Byung Chul [Ewha Womans University College of Medicine, Seoul (Korea, Republic of)

    1999-12-15

    To demonstrate sonographic features of Hashimoto's thyroiditis according to the thyroid function. We reviewed 54 thyroid ultrasonographic examinations of untreated Hashimoto's thyroiditis. We reviewed thyroid ultrasonographic examinations and focused on the presence of ill-defined low echoic lesions and glandular enlargement. We performed another thyroid ultrasonographic examination of 14 healthy volunteers, in order to obtain normal size of thyroid gland. Comparison was made between these morphologic characteristics and functional stage of the disease. The mean diameter of thyroid gland was 2.16 {+-} 0.43 cm in patients with Hashimoto's thyroiditis, and 1.41 {+-} 0.42 cm in normal control group of the thyroid gland. There was no statistically significant relationship between thyroid function and size. There was morphologic abnormalities in 46 patients (85%). Among them, 7 patients revealed diffuse low echogenicity in the entire thyroid gland, 32 patients showed peripherally located, ill-defined focal hypoechoic lesion, and 7 patients showed solitary or multiple. well-defined nodular lesions. Decreased echogenicity of the thyroid gland was related to hypothyroid status. Hashimoto's thyroiditis has specific morphologue characteristics in ultrasonographic features, which are well correlated with thyroid function.

  11. Electron and Phonon Transport in Molecular Junctions

    DEFF Research Database (Denmark)

    Li, Qian

    Molecular electronics provide the possibility to investigate electron and phonon transport at the smallest imaginable scale, where quantum effects can be investigated and exploited directly in the design. In this thesis, we study both electron transport and phonon transport in molecular junctions....... The system we are interested in here are π-stacked molecules connected with two semi-infinite leads. π-stacked aromatic rings, connected via π-π electronic coupling, provides a rather soft mechanical bridge while maintaining high electronic conductivity. We investigate electron transport...... transmission at the Fermi energy. We propose and analyze a way of using π   stacking to design molecular junctions to control heat transport. We develop a simple model system to identify optimal parameter regimes and then use density functional theory (DFT) to extract model parameters for a number of specific...

  12. Relaxation oscillation logic in Josephson junction circuits

    International Nuclear Information System (INIS)

    Fulton, T.A.

    1981-01-01

    A dc powered, self-resetting Josephson junction logic circuit relying on relaxation oscillations is described. A pair of Josephson junction gates are connected in series, a first shunt is connected in parallel with one of the gates, and a second shunt is connected in parallel with the series combination of gates. The resistance of the shunts and the dc bias current bias the gates so that they are capable of undergoing relaxation oscillations. The first shunt forms an output line whereas the second shunt forms a control loop. The bias current is applied to the gates so that, in the quiescent state, the gate in parallel with the second shunt is at V O, and the other gate is undergoing relaxation oscillations. By controlling the state of the first gate with the current in the output loop of another identical circuit, the invert function is performed

  13. Emission of partial dislocations from triple junctions of grain boundaries in nanocrystalline materials

    International Nuclear Information System (INIS)

    Gutkin, M Yu; Ovid'ko, I A; Skiba, N V

    2005-01-01

    A theoretical model is suggested that describes emission of partial Shockley dislocations from triple junctions of grain boundaries (GBs) in deformed nanocrystalline materials. In the framework of the model, triple junctions accumulate dislocations due to GB sliding along adjacent GBs. The dislocation accumulation at triple junctions causes partial Shockley dislocations to be emitted from the dislocated triple junctions and thus accommodates GB sliding. Ranges of parameters (applied stress, grain size, etc) are calculated in which the emission events are energetically favourable in nanocrystalline Al, Cu and Ni. The model accounts for the corresponding experimental data reported in the literature

  14. Human health no-effect levels of TiO{sub 2} nanoparticles as a function of their primary size

    Energy Technology Data Exchange (ETDEWEB)

    Laurent, Alexis, E-mail: alau@dtu.dk [Technical University of Denmark, Division for Quantitative Sustainability Assessment, Department of Management Engineering (Denmark); Harkema, Jack R. [Michigan State University, Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine (United States); Andersen, Elisabeth W. [Technical University of Denmark, Statistics and Data Analysis Section, Department of Applied Mathematics and Computer Science (Denmark); Owsianiak, Mikołaj; Vea, Eldbjørg B. [Technical University of Denmark, Division for Quantitative Sustainability Assessment, Department of Management Engineering (Denmark); Jolliet, Olivier [University of Michigan, Department of Environmental Health Sciences, School of Public Health (United States)

    2017-04-15

    As engineered nanomaterials are increasingly introduced on the market into a broad range of commodities or nanoproducts, there is a need for operational, reliable tool, enabling to consistently assess the risks and impacts associated with the releases of nanoparticles. The lack of a developed metric that accurately represents their toxic effects while capturing the influence of the most relevant physicochemical properties is one of the major impediments. Here, we investigate the relationships between the toxic responses of nano-sized and micro-sized particles in in vivo toxicological studies and their physicochemical properties. Our results for TiO{sub 2} particles indicate statistically significant associations between the primary particle size and their toxicity responses for combined inhalation and ingestion exposure routes, although the numerical values should be considered with care due to the inability to encompass influences from other relevant physicochemical properties like surface coatings. These findings allow for expressing mass-based adverse effect levels as a continuous function of the primary size of particles. This meaningful, exploratory metric can thus be used for screening purposes and pave the way for reaching adaptive, robust risk assessments of nanomaterials, e.g. for setting up consistent threshold levels, as well as consistent life cycle assessments of nanoproducts. We provide examples of such applications.

  15. Human health no-effect levels of TiO_2 nanoparticles as a function of their primary size

    International Nuclear Information System (INIS)

    Laurent, Alexis; Harkema, Jack R.; Andersen, Elisabeth W.; Owsianiak, Mikołaj; Vea, Eldbjørg B.; Jolliet, Olivier

    2017-01-01

    As engineered nanomaterials are increasingly introduced on the market into a broad range of commodities or nanoproducts, there is a need for operational, reliable tool, enabling to consistently assess the risks and impacts associated with the releases of nanoparticles. The lack of a developed metric that accurately represents their toxic effects while capturing the influence of the most relevant physicochemical properties is one of the major impediments. Here, we investigate the relationships between the toxic responses of nano-sized and micro-sized particles in in vivo toxicological studies and their physicochemical properties. Our results for TiO_2 particles indicate statistically significant associations between the primary particle size and their toxicity responses for combined inhalation and ingestion exposure routes, although the numerical values should be considered with care due to the inability to encompass influences from other relevant physicochemical properties like surface coatings. These findings allow for expressing mass-based adverse effect levels as a continuous function of the primary size of particles. This meaningful, exploratory metric can thus be used for screening purposes and pave the way for reaching adaptive, robust risk assessments of nanomaterials, e.g. for setting up consistent threshold levels, as well as consistent life cycle assessments of nanoproducts. We provide examples of such applications.

  16. Drop size distribution measured by imaging: determination of the measurement volume by the calibration of the point spread function

    International Nuclear Information System (INIS)

    Fdida, Nicolas; Blaisot, Jean-Bernard

    2010-01-01

    Measurement of drop size distributions in a spray depends on the definition of the control volume for drop counting. For image-based techniques, this implies the definition of a depth-of-field (DOF) criterion. A sizing procedure based on an imaging model and associated with a calibration procedure is presented. Relations between image parameters and object properties are used to provide a measure of the size of the droplets, whatever the distance from the in-focus plane. A DOF criterion independent of the size of the drops and based on the determination of the width of the point spread function (PSF) is proposed. It allows to extend the measurement volume to defocused droplets and, due to the calibration of the PSF, to clearly define the depth of the measurement volume. Calibrated opaque discs, calibrated pinholes and an optical edge are used for this calibration. A comparison of the technique with a phase Doppler particle analyser and a laser diffraction granulometer is performed on an application to an industrial spray. Good agreement is found between the techniques when particular care is given to the sampling of droplets. The determination of the measurement volume is used to determine the drop concentration in the spray and the maximum drop concentration that imaging can support

  17. Escaping Electrons from Intense Laser-Solid Interactions as a Function of Laser Spot Size

    Directory of Open Access Journals (Sweden)

    Rusby Dean

    2018-01-01

    Full Text Available The interaction of a high-intensity laser with a solid target produces an energetic distribution of electrons that pass into the target. These electrons reach the rear surface of the target creating strong electric potentials that act to restrict the further escape of additional electrons. The measurement of the angle, flux and spectra of the electrons that do escape gives insights to the initial interaction. Here, the escaping electrons have been measured using a differentially filtered image plate stack, from interactions with intensities from mid 1020-1017 W/cm2, where the intensity has been reduced by defocussing to increase the size of the focal spot. An increase in electron flux is initially observed as the intensity is reduced from 4x1020 to 6x1018 W/cm2. The temperature of the electron distribution is also measured and found to be relatively constant. 2D particle-in-cell modelling is used to demonstrate the importance of pre-plasma conditions in understanding these observations.

  18. Heat Transport in Graphene Ferromagnet-Insulator-Superconductor Junctions

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-Wei

    2011-01-01

    We study heat transport in a graphene ferromagnet-insulator-superconducting junction. It is found that the thermal conductance of the graphene ferromagnet-insulator-superconductor (FIS) junction is an oscillatory function of the barrier strength x in the thin-barrier limit. The gate potential U0 decreases the amplitude of thermal conductance oscillation. Both the amplitude and phase of the thermal conductance oscillation varies with the exchange energy Eh. The thermal conductance of a graphene FIS junction displays the usual exponential dependence on temperature, reflecting the s-wave symmetry of superconducting graphene.%@@ We study heat transport in a graphene ferromagnet-insulator-superconducting junction.It is found that the thermal conductance of the graphene ferromagnet-insulator-superconductor(FIS)junction is an oscillatory function of the barrier strength X in the thin-barrier limit.The gate potential Uo decreases the amplitude of thermal conductance oscillation.Both the amplitude and phase of the thermal conductance oscillation varies with the exchange energy Eh.The thermal conductance of a graphene FIS junction displays the usual exponential dependence on temperature, reflecting the s-wave symmetry of superconducting graphene.

  19. Quantum transport through mesoscopic disordered interfaces, junctions, and multilayers

    International Nuclear Information System (INIS)

    Nikolic, Branislav K.

    2002-01-01

    This study explores perpendicular transport through macroscopically inhomogeneous three-dimensional disordered conductors using mesoscopic methods (the real-space Green function technique in a two-probe measuring geometry). The nanoscale samples (containing ∼ 1000 atoms) are modelled by a tight-binding Hamiltonian on a simple cubic lattice where disorder is introduced in the on-site potential energy. I compute the transport properties of: disordered metallic junctions formed by concatenating two homogeneous samples with different kinds of microscopic disorder, a single strongly disordered interface, and multilayers composed of such interfaces and homogeneous layers characterized by different strengths of the same type of microscopic disorder. This allows us to: contrast the resistor model (semiclassical) approach with a fully quantum description of dirty mesoscopic multilayers; study the transmission properties of dirty interfaces (where the Schep-Bauer distribution of transmission eigenvalues is confirmed for a single interface, as well as for a stack of such interfaces that is thinner than the localization length); and elucidate the effect of coupling to ideal leads ('measuring apparatus') on the conductance of both bulk conductors and dirty interfaces. When a multilayer contains a ballistic layer in between two interfaces, its disorder-averaged conductance oscillates as a function of the Fermi energy. I also address some fundamental issues in quantum transport theory - the relationship between the Kubo formula in the exact state representation and the 'mesoscopic Kubo formula' (which gives the exact zero-temperature conductance of a finite-size sample attached to two semi-infinite ideal leads) is thoroughly re-examined by comparing their outcomes for both the junctions and homogeneous samples. (author)

  20. Molecular conformation changes in alkylthiol ligands as a function of size in gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ramallo-Lopez, J.M.; Giovanetti, L.J.; Requejo, F.G. [Universidad Nacional de La Plata, Buenos Aires (Argentina); Isaacs, S.R.; Shon, Y.S. [Western Kentucky University, KY (United States); Salmeron, M. [Lawrence Berkeley National Laboratory, Berkeley, CA (United States)

    2006-07-01

    The binding of thiol molecules to gold, and in particular to gold nanoparticles (NP), is important in sensors, self-assembled monolayers and many other nanotechnological applications. For example, organic-thiolate s are extensively used as capping agents to prevent metal particle sintering and as ligands that can be functionalized to provide desirable chemical properties. An interesting feature of alkyl hydrocarbon chains is their flexibility, which allows them to change conformation to maximize space filling. This is driven by the inter-chain van der Waals nervy, which is considerably higher for longer chains and can be comparable to the stronger covalent bond of the S head with the Au. On the other hand, chain flexibility is facilitated by the easy formation of gauche distortions which require activation energies of only 0.16 eV. (author)

  1. Brain size and neuropsychological functioning in long-term survivors of pediatric acute lymphoblastic leukemia.

    Science.gov (United States)

    Mulcahy Levy, Jean M; Hunger, Stephen P

    2013-10-01

    With the increased survival of pediatric cancer patients the interest in the late effects of treatments is rapidly increasing. Long-term survival rates for children with acute lymphoblastic leukemia (ALL) now approach 90%. Treatment for ALL includes intensified central nervous system (CNS)-directed therapy, which is associated with risks for long-term neurocognitive effects. It is becoming clear that current therapies can have not only a detrimental effect on IQ, processing speed, and memory, but also on structural changes that lead to permanent alterations of the organization of the CNS. Understanding how the CNS is affected by the treatments is a critical step in evaluating current therapies and developing interventions to decrease the incidence and severity of long-term changes in brain anatomy and function.

  2. Effect of Morphology and Size of Halloysite Nanotubes on Functional Pectin Bionanocomposites for Food Packaging Applications.

    Science.gov (United States)

    Makaremi, Maziyar; Pasbakhsh, Pooria; Cavallaro, Giuseppe; Lazzara, Giuseppe; Aw, Yoong Kit; Lee, Sui Mae; Milioto, Stefana

    2017-05-24

    Pectin bionanocomposite films filled with various concentrations of two different types of halloysite nanotubes were prepared and characterized in this study as potential films for food packaging applications. The two types of halloysite nanotubes were long and thin (patch) (200-30 000 nm length) and short and stubby (Matauri Bay) (50-3000 nm length) with different morphological, physical, and dispersibility properties. Both matrix (pectin) and reinforcer (halloysite nanotubes) used in this study are considered as biocompatible, natural, and low-cost materials. Various characterization tests including Fourier transform infrared spectroscopy, field emission scanning electron microscopy, release kinetics, contact angle, and dynamic mechanical analysis were performed to evaluate the performance of the pectin films. Exceptional thermal, tensile, and contact angle properties have been achieved for films reinforced by patch halloysite nanotubes due to the patchy and lengthy nature of these tubes, which form a bird nest structure in the pectin matrix. Matauri Bay halloysite nanotubes were dispersed uniformly and individually in the matrix in low and even high halloysite nanotube concentrations. Furthermore, salicylic acid as a biocidal agent was encapsulated in the halloysite nanotubes lumen to control its release kinetics. On this basis, halloysite nanotubes/salicylic acid hybrids were dispersed into the pectin matrix to develop functional biofilms with antimicrobial properties that can be extended over time. Results revealed that shorter nanotubes (Matauri Bay) had better ability for the encapsulation of salicylic acid into their lumen, while patchy structure and longer tubes of patch halloysite nanotubes made the encapsulation process more difficult, as they might need more time and energy to be fully loaded by salicylic acid. Moreover, antimicrobial activity of the films against four different strains of Gram-positive and Gram-negative bacteria indicated the

  3. First-principle study of quantum confinement effect on small sized silicon quantum dots using density-functional theory

    International Nuclear Information System (INIS)

    Anas, M. M.; Othman, A. P.; Gopir, G.

    2014-01-01

    Density functional theory (DFT), as a first-principle approach has successfully been implemented to study nanoscale material. Here, DFT by numerical basis-set was used to study the quantum confinement effect as well as electronic properties of silicon quantum dots (Si-QDs) in ground state condition. Selection of quantum dot models were studied intensively before choosing the right structure for simulation. Next, the computational result were used to examine and deduce the electronic properties and its density of state (DOS) for 14 spherical Si-QDs ranging in size up to ∼ 2 nm in diameter. The energy gap was also deduced from the HOMO-LUMO results. The atomistic model of each silicon QDs was constructed by repeating its crystal unit cell of face-centered cubic (FCC) structure, and reconstructed until the spherical shape obtained. The core structure shows tetrahedral (T d ) symmetry structure. It was found that the model need to be passivated, and hence it was noticed that the confinement effect was more pronounced. The model was optimized using Quasi-Newton method for each size of Si-QDs to get relaxed structure before it was simulated. In this model the exchange-correlation potential (V xc ) of the electrons was treated by Local Density Approximation (LDA) functional and Perdew-Zunger (PZ) functional

  4. Instabilities in thin tunnel junctions

    International Nuclear Information System (INIS)

    Konkin, M.K.; Adler, J.G.

    1978-01-01

    Tunnel junctions prepared for inelastic electron tunneling spectroscopy are often plagued by instabilities in the 0-500-meV range. This paper relates the bias at which the instability occurs to the barrier thickness

  5. The Control of Junction Flows

    National Research Council Canada - National Science Library

    Smith, Charles

    1997-01-01

    An experimental study of the effects of spatially-limited (i.e. localized) surface suction on unsteady laminar and turbulent junction flows was performed using hydrogen bubble flow visualization and Particle Image Velocimetry (PIV...

  6. Edge Artifacts in Point Spread Function-based PET Reconstruction in Relation to Object Size and Reconstruction Parameters

    Directory of Open Access Journals (Sweden)

    Yuji Tsutsui

    2017-06-01

    Full Text Available Objective(s: We evaluated edge artifacts in relation to phantom diameter and reconstruction parameters in point spread function (PSF-based positron emission tomography (PET image reconstruction.Methods: PET data were acquired from an original cone-shaped phantom filled with 18F solution (21.9 kBq/mL for 10 min using a Biograph mCT scanner. The images were reconstructed using the baseline ordered subsets expectation maximization (OSEM algorithm and the OSEM with PSF correction model. The reconstruction parameters included a pixel size of 1.0, 2.0, or 3.0 mm, 1-12 iterations, 24 subsets, and a full width at half maximum (FWHM of the post-filter Gaussian filter of 1.0, 2.0, or 3.0 mm. We compared both the maximum recovery coefficient (RCmax and the mean recovery coefficient (RCmean in the phantom at different diameters.Results: The OSEM images had no edge artifacts, but the OSEM with PSF images had a dense edge delineating the hot phantom at diameters 10 mm or more and a dense spot at the center at diameters of 8 mm or less. The dense edge was clearly observed on images with a small pixel size, a Gaussian filter with a small FWHM, and a high number of iterations. At a phantom diameter of 6-7 mm, the RCmax for the OSEM and OSEM with PSF images was 60% and 140%, respectively (pixel size: 1.0 mm; FWHM of the Gaussian filter: 2.0 mm; iterations: 2. The RCmean of the OSEM with PSF images did not exceed 100%.Conclusion: PSF-based image reconstruction resulted in edge artifacts, the degree of which depends on the pixel size, number of iterations, FWHM of the Gaussian filter, and object size.

  7. Functional characterization of the water-soluble organic carbon of size-fractionated aerosol in the southern Mississippi Valley

    Science.gov (United States)

    Chalbot, M.-C. G.; Brown, J.; Chitranshi, P.; Gamboa da Costa, G.; Pollock, E. D.; Kavouras, I. G.

    2014-06-01

    The chemical content of water-soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for periods when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5% of particle mass for particles with dp > 0.96 μm and 10% of particle mass for particles with dp magnetic resonance (1H-NMR). The total non-exchangeable organic hydrogen concentrations varied from 4.1 ± 0.1 nmol m-3 for particles with 1.5 fingerprints of fine particles. Sucrose, fructose, glucose, formate and acetate were associated with coarse particles. These qualitative differences of 1H-NMR profiles for different particle sizes indicated the possible contribution of biological aerosols and a mixture of aliphatic and oxygenated compounds from biomass burning and traffic exhausts. The concurrent presence of ammonium and amines also suggested the presence of ammonium/aminium nitrate and sulfate secondary aerosol. The size-dependent origin of WSOC was further corroborated by the increasing δ13C abundance from -26.81 ± 0.18‰ for the smallest particles to -25.93 ± 0.31‰ for the largest particles and the relative distribution of the functional groups as compared to those previously observed for marine, biomass burning and secondary organic aerosol. The latter also allowed for the differentiation of urban combustion-related aerosol and biological particles. The five types of organic hydrogen accounted for the majority of WSOC for particles with dp > 3.0 μm and dp < 0.96 μm.

  8. Functional characterization of the water-soluble organic carbon of size fractionated aerosol in the Southern Mississippi Valley

    Science.gov (United States)

    Chalbot, M.-C. G.; Brown, J.; Chitranshi, P.; Gamboa da Costa, G.; Pollock, E. D.; Kavouras, I. G.

    2014-02-01

    The chemical content of the water soluble organic carbon (WSOC) as a function of particle size was characterized in Little Rock, Arkansas in winter and spring 2013. The objectives of this study were to: (i) compare the functional characteristics of coarse, fine and ultrafine WSOC and (ii) reconcile the sources of WSOC for the period when carbonaceous aerosol was the most abundant particulate component. The WSOC accounted for 5% of particle mass for particles with dp > 0.96 μm and 10% of particle mass for particles with dp magnetic resonance. The total non-exchangeable organic hydrogen concentrations varied from 4.1 ± 0.1 nmol m-3 for particles with 0.96 fingerprints of fine particles. Sucrose, fructose, glucose, formate and acetate were associated with coarse particles. These qualitative differences of 1H-NMR profiles for different particle sizes indicated the possible contribution of biological aerosol and a mixture of aliphatic and oxygenated compounds from biomass burning and traffic exhausts. The concurrent presence of ammonium and amines also suggested the presence of ammonium/aminium nitrate and sulfate secondary aerosol. The size-dependent origin of WSOC was further corroborated by the increasing δ13C abundance from -26.81 ± 0.18‰ for the smallest particles to -25.93 ± 0.31‰ for the largest particles and the relative distribution of the functional groups as compared to those previously observed for marine, biomass burning and secondary organic aerosol. The latter also allowed for the differentiation of urban combustion-related aerosol and biological particles. The five types of organic hydrogen accounted for the majority of WSOC for particles with dp > 3.0 μm and dp < 0.96 μm.

  9. Josephson junctions with ferromagnetic interlayer

    International Nuclear Information System (INIS)

    Wild, Georg Hermann

    2012-01-01

    We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlO x /Pd 0.82 Ni 0.18 /Nb) Josephson junctions (SIFS JJs) with high critical current densities, large normal resistance times area products, and high quality factors. For these junctions, a transition from 0- to π-coupling is observed for a thickness d F =6 nm of the ferromagnetic Pd 0.82 Ni 0.18 interlayer. The magnetic field dependence of the critical current of the junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd 0.82 Ni 0.18 has an out-of-plane anisotropy and large saturation magnetization indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes up to about 400 GHz provides valuable information on the junction quality factor and the relevant damping mechanisms. Whereas losses due to quasiparticle tunneling dominate at low frequencies, at high frequencies the damping is explained by the finite surface resistance of the junction electrodes. High quality factors of up to 30 around 200 GHz have been achieved. They allow to study the junction dynamics, in particular the switching probability from the zero-voltage into the voltage state with and without microwave irradiation. The experiments with microwave irradiation are well explained within semi-classical models and numerical simulations. In contrast, at mK temperature the switching dynamics without applied microwaves clearly shows secondary quantum effects. Here, we could observe for the first time macroscopic quantum tunneling in Josephson junctions with a ferromagnetic interlayer. This observation excludes fluctuations of the critical current as a consequence of an unstable magnetic domain structure of the ferromagnetic interlayer and affirms the suitability of SIFS Josephson junctions for quantum information processing.

  10. Josephson junctions with ferromagnetic interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Wild, Georg Hermann

    2012-03-04

    We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlO{sub x}/Pd{sub 0.82}Ni{sub 0.18}/Nb) Josephson junctions (SIFS JJs) with high critical current densities, large normal resistance times area products, and high quality factors. For these junctions, a transition from 0- to {pi}-coupling is observed for a thickness d{sub F}=6 nm of the ferromagnetic Pd{sub 0.82}Ni{sub 0.18} interlayer. The magnetic field dependence of the critical current of the junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd{sub 0.82}Ni{sub 0.18} has an out-of-plane anisotropy and large saturation magnetization indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes up to about 400 GHz provides valuable information on the junction quality factor and the relevant damping mechanisms. Whereas losses due to quasiparticle tunneling dominate at low frequencies, at high frequencies the damping is explained by the finite surface resistance of the junction electrodes. High quality factors of up to 30 around 200 GHz have been achieved. They allow to study the junction dynamics, in particular the switching probability from the zero-voltage into the voltage state with and without microwave irradiation. The experiments with microwave irradiation are well explained within semi-classical models and numerical simulations. In contrast, at mK temperature the switching dynamics without applied microwaves clearly shows secondary quantum effects. Here, we could observe for the first time macroscopic quantum tunneling in Josephson junctions with a ferromagnetic interlayer. This observation excludes fluctuations of the critical current as a consequence of an unstable magnetic domain structure of the ferromagnetic interlayer and affirms the suitability of SIFS Josephson junctions for quantum information processing.

  11. Universal Exciton Size in Organic Polymers is Determined by Nonlocal Orbital Exchange in Time-Dependent Density Functional Theory.

    Science.gov (United States)

    Mewes, Stefanie A; Plasser, Felix; Dreuw, Andreas

    2017-03-16

    The exciton size of the lowest singlet excited state in a diverse set of organic π-conjugated polymers is studied and found to be a universal, system-independent quantity of approximately 7 Å in the single-chain picture. With time-dependent density functional theory (TDDFT), its value as well as the overall description of the exciton is almost exclusively governed by the amount of nonlocal orbital exchange. This is traced back to the lack of the Coulomb attraction between the electron and hole quasiparticles in pure TDDFT, which is reintroduced only with the admixture of nonlocal orbital exchange.

  12. AFM topographies of densely packed nanoparticles: a quick way to determine the lateral size distribution by autocorrelation function analysis

    Czech Academy of Sciences Publication Activity Database

    Fekete, Ladislav; Kůsová, Kateřina; Petrák, Václav; Kratochvílová, Irena

    2012-01-01

    Roč. 14, č. 8 (2012), s. 1-10 ISSN 1388-0764 R&D Projects: GA AV ČR KAN200100801; GA TA ČR TA01011165; GA ČR(CZ) GAP304/10/1951; GA ČR GPP204/12/P235 Institutional research plan: CEZ:AV0Z10100520 Keywords : lateral grain size distribution * AFM * autocorrelation function * nanodiamond Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.175, year: 2012

  13. Sizing of SRAM Cell with Voltage Biasing Techniques for Reliability Enhancement of Memory and PUF Functions

    Directory of Open Access Journals (Sweden)

    Chip-Hong Chang

    2016-08-01

    Full Text Available Static Random Access Memory (SRAM has recently been developed into a physical unclonable function (PUF for generating chip-unique signatures for hardware cryptography. The most compelling issue in designing a good SRAM-based PUF (SPUF is that while maximizing the mismatches between the transistors in the cross-coupled inverters improves the quality of the SPUF, this ironically also gives rise to increased memory read/write failures. For this reason, the memory cells of existing SPUFs cannot be reused as storage elements, which increases the overheads of cryptographic system where long signatures and high-density storage are both required. This paper presents a novel design methodology for dual-mode SRAM cell optimization. The design conflicts are resolved by using word-line voltage modulation, dynamic voltage scaling, negative bit-line and adaptive body bias techniques to compensate for reliability degradation due to transistor downsizing. The augmented circuit-level techniques expand the design space to achieve a good solution to fulfill several otherwise contradicting key design qualities for both modes of operation, as evinced by our statistical analysis and simulation results based on complementary metal–oxide–semiconductor (CMOS 45 nm bulk Predictive Technology Model.

  14. Electronic thermometry in tunable tunnel junction

    Science.gov (United States)

    Maksymovych, Petro

    2016-03-15

    A tunable tunnel junction thermometry circuit includes a variable width tunnel junction between a test object and a probe. The junction width is varied and a change in thermovoltage across the junction with respect to the change in distance across the junction is determined. Also, a change in biased current with respect to a change in distance across the junction is determined. A temperature gradient across the junction is determined based on a mathematical relationship between the temperature gradient, the change in thermovoltage with respect to distance and the change in biased current with respect to distance. Thermovoltage may be measured by nullifying a thermoelectric tunneling current with an applied voltage supply level. A piezoelectric actuator may modulate the probe, and thus the junction width, to vary thermovoltage and biased current across the junction. Lock-in amplifiers measure the derivatives of the thermovoltage and biased current modulated by varying junction width.

  15. Changes of junctions of endothelial cells in coronary sclerosis: A review

    Directory of Open Access Journals (Sweden)

    Li-Zi Zhang

    2016-03-01

    Full Text Available Atherosclerosis, the major cause of cardiovascular diseases, has been a leading contributor to morbidity and mortality in the United States and it has been on the rise globally. Endothelial cell–cell junctions are critical for vascular integrity and maintenance of vascular function. Endothelial cell junctions dysfunction is the onset step of future coronary events and coronary artery disease. Keywords: Coronary atherosclerosis, Junctions, Endothelial cells

  16. Photoluminescence effects of graphitic core size and surface functional groups in carbon dots: COO− induced red-shift emission

    KAUST Repository

    Hola, Katerina

    2014-04-01

    We present a simple molecular approach to control the lipophilic/ hydrophilic nature of photoluminescent carbon dots (CDs) based on pyrolysis of alkyl gallate precursors. Depending on the gallic acid derivative used, CDs with different alkyl groups (methyl, propyl, lauryl) on the surface can be obtained by isothermal heating at 270 C. This precursor-derived approach allows not only the control of lipophilicity but also the length of the particular alkyl chain enables the control over both the size and photoluminescence (PL) of the prepared CDs. Moreover, the alkyl chains on the CDs surface can be readily converted to carboxylate groups via a mild base hydrolysis to obtain water dispersible CDs with a record biocompatibility. The observed differences in PL properties of CDs and time-resolved PL data, including contributions from carbogenic cores and surface functional group, are rationalized and discussed in detail using time-dependent density functional theory (TD-DFT) calculations. © 2013 Elsevier Ltd. All rights reserved.

  17. Photoluminescence effects of graphitic core size and surface functional groups in carbon dots: COO− induced red-shift emission

    KAUST Repository

    Hola, Katerina; Bourlinos, Athanasios B.; Kozak, Ondrej; Berka, Karel; Siskova, Karolina M.; Havrdova, Marketa; Tucek, Jiri; Safarova, Klara; Otyepka, Michal; Giannelis, Emmanuel P.; Zboril, Radek

    2014-01-01

    We present a simple molecular approach to control the lipophilic/ hydrophilic nature of photoluminescent carbon dots (CDs) based on pyrolysis of alkyl gallate precursors. Depending on the gallic acid derivative used, CDs with different alkyl groups (methyl, propyl, lauryl) on the surface can be obtained by isothermal heating at 270 C. This precursor-derived approach allows not only the control of lipophilicity but also the length of the particular alkyl chain enables the control over both the size and photoluminescence (PL) of the prepared CDs. Moreover, the alkyl chains on the CDs surface can be readily converted to carboxylate groups via a mild base hydrolysis to obtain water dispersible CDs with a record biocompatibility. The observed differences in PL properties of CDs and time-resolved PL data, including contributions from carbogenic cores and surface functional group, are rationalized and discussed in detail using time-dependent density functional theory (TD-DFT) calculations. © 2013 Elsevier Ltd. All rights reserved.

  18. Edge currents in frustrated Josephson junction ladders

    Science.gov (United States)

    Marques, A. M.; Santos, F. D. R.; Dias, R. G.

    2016-09-01

    We present a numerical study of quasi-1D frustrated Josephson junction ladders with diagonal couplings and open boundary conditions, in the large capacitance limit. We derive a correspondence between the energy of this Josephson junction ladder and the expectation value of the Hamiltonian of an analogous tight-binding model, and show how the overall superconducting state of the chain is equivalent to the minimum energy state of the tight-binding model in the subspace of one-particle states with uniform density. To satisfy the constraint of uniform density, the superconducting state of the ladder is written as a linear combination of the allowed k-states of the tight-binding model with open boundaries. Above a critical value of the parameter t (ratio between the intra-rung and inter-rung Josephson couplings) the ladder spontaneously develops currents at the edges, which spread to the bulk as t is increased until complete coverage is reached. Above a certain value of t, which varies with ladder size (t = 1 for an infinite-sized ladder), the edge currents are destroyed. The value t = 1 corresponds, in the tight-binding model, to the opening of a gap between two bands. We argue that the disappearance of the edge currents with this gap opening is not coincidental, and that this points to a topological origin for these edge current states.

  19. Magnetoresistance of galfenol-based magnetic tunnel junction

    International Nuclear Information System (INIS)

    Gobaut, B.; Vinai, G.; Castán-Guerrero, C.; Krizmancic, D.; Panaccione, G.; Torelli, P.; Rafaqat, H.; Roddaro, S.; Rossi, G.; Eddrief, M.; Marangolo, M.

    2015-01-01

    The manipulation of ferromagnetic layer magnetization via electrical pulse is driving an intense research due to the important applications that this result will have on memory devices and sensors. In this study we realized a magnetotunnel junction in which one layer is made of Galfenol (Fe 1-x Ga x ) which possesses one of the highest magnetostrictive coefficient known. The multilayer stack has been grown by molecular beam epitaxy and e-beam evaporation. Optical lithography and physical etching have been combined to obtain 20x20 micron sized pillars. The obtained structures show tunneling conductivity across the junction and a tunnel magnetoresistance (TMR) effect of up to 11.5% in amplitude

  20. Sample size requirements for studies of treatment effects on beta-cell function in newly diagnosed type 1 diabetes.

    Science.gov (United States)

    Lachin, John M; McGee, Paula L; Greenbaum, Carla J; Palmer, Jerry; Pescovitz, Mark D; Gottlieb, Peter; Skyler, Jay

    2011-01-01

    Preservation of β-cell function as measured by stimulated C-peptide has recently been accepted as a therapeutic target for subjects with newly diagnosed type 1 diabetes. In recently completed studies conducted by the Type 1 Diabetes Trial Network (TrialNet), repeated 2-hour Mixed Meal Tolerance Tests (MMTT) were obtained for up to 24 months from 156 subjects with up to 3 months duration of type 1 diabetes at the time of study enrollment. These data provide the information needed to more accurately determine the sample size needed for future studies of the effects of new agents on the 2-hour area under the curve (AUC) of the C-peptide values. The natural log(x), log(x+1) and square-root (√x) transformations of the AUC were assessed. In general, a transformation of the data is needed to better satisfy the normality assumptions for commonly used statistical tests. Statistical analysis of the raw and transformed data are provided to estimate the mean levels over time and the residual variation in untreated subjects that allow sample size calculations for future studies at either 12 or 24 months of follow-up and among children 8-12 years of age, adolescents (13-17 years) and adults (18+ years). The sample size needed to detect a given relative (percentage) difference with treatment versus control is greater at 24 months than at 12 months of follow-up, and differs among age categories. Owing to greater residual variation among those 13-17 years of age, a larger sample size is required for this age group. Methods are also described for assessment of sample size for mixtures of subjects among the age categories. Statistical expressions are presented for the presentation of analyses of log(x+1) and √x transformed values in terms of the original units of measurement (pmol/ml). Analyses using different transformations are described for the TrialNet study of masked anti-CD20 (rituximab) versus masked placebo. These results provide the information needed to accurately

  1. Sample size requirements for studies of treatment effects on beta-cell function in newly diagnosed type 1 diabetes.

    Directory of Open Access Journals (Sweden)

    John M Lachin

    Full Text Available Preservation of β-cell function as measured by stimulated C-peptide has recently been accepted as a therapeutic target for subjects with newly diagnosed type 1 diabetes. In recently completed studies conducted by the Type 1 Diabetes Trial Network (TrialNet, repeated 2-hour Mixed Meal Tolerance Tests (MMTT were obtained for up to 24 months from 156 subjects with up to 3 months duration of type 1 diabetes at the time of study enrollment. These data provide the information needed to more accurately determine the sample size needed for future studies of the effects of new agents on the 2-hour area under the curve (AUC of the C-peptide values. The natural log(x, log(x+1 and square-root (√x transformations of the AUC were assessed. In general, a transformation of the data is needed to better satisfy the normality assumptions for commonly used statistical tests. Statistical analysis of the raw and transformed data are provided to estimate the mean levels over time and the residual variation in untreated subjects that allow sample size calculations for future studies at either 12 or 24 months of follow-up and among children 8-12 years of age, adolescents (13-17 years and adults (18+ years. The sample size needed to detect a given relative (percentage difference with treatment versus control is greater at 24 months than at 12 months of follow-up, and differs among age categories. Owing to greater residual variation among those 13-17 years of age, a larger sample size is required for this age group. Methods are also described for assessment of sample size for mixtures of subjects among the age categories. Statistical expressions are presented for the presentation of analyses of log(x+1 and √x transformed values in terms of the original units of measurement (pmol/ml. Analyses using different transformations are described for the TrialNet study of masked anti-CD20 (rituximab versus masked placebo. These results provide the information needed to

  2. Integration of organic based Schottky junctions for crossbar non-volatile memory applications

    DEFF Research Database (Denmark)

    Katsia, E.; Tallarida, G.; Ferrari, S.

    2008-01-01

    Small size Schottky junctions using two different synthesized organic semiconductors (oligophenylene-vinylenes) were integrated by standard UV lithography into crossbar arrays. The proposed integration scheme can be applied to a wide class of organics without affecting material properties. Current...

  3. High-Performance Flexible Magnetic Tunnel Junctions for Smart Miniaturized Instruments

    KAUST Repository

    Amara, Selma.; Sevilla, Gallo. A. Torres; Hawsawi, Mayyada.; Mashraei, Yousof.; Mohammed, Hanan .; Cruz, Melvin E.; Ivanov, Yurii. P.; Jaiswal, Samridh.; Jakob, Gerhard.; Klä ui, Mathias.; Hussain, Muhammad.; Kosel, Jurgen.

    2018-01-01

    , where size and weight are critical parameters. Given their prevalence on the sensors market, flexible magnetic sensors play a major role in this progress. For many high-performance applications, magnetic tunnel junctions (MTJs) have become the first

  4. One-pot solvothermal synthesis of highly water-dispersible size-tunable functionalized magnetite nanocrystal clusters for lipase immobilization.

    Science.gov (United States)

    Zhu, Hao; Hou, Chen; Li, Yijing; Zhao, Guanghui; Liu, Xiao; Hou, Ke; Li, Yanfeng

    2013-07-01

    A facile one-pot synthesis of highly water-dispersible size-tunable magnetite (Fe3O4) nanocrystal clusters (MNCs) end-functionalized with amino or carboxyl groups by a modified solvothermal reduction reaction has been developed. Dopamine and 3,4-dihydroxyhydroxycinnamic acid were used for the first time as both a surfactant and interparticle linker in a polylol process for economical and environment-friendly purposes. Morphology, chemical composition, and magnetic properties of the prepared particles were investigated by several methods, including FESEM, TEM, XRD, XPS, Raman, FTIR, TGA, zeta potential, and VSM. The sizes of the particles could be easily tuned over a wide range from 175 to 500 nm by varying the surfactant concentration. Moreover, ethylene glycol/diethylene glycol (EG/DEG) solvent mixtures with different ratios could be used as reductants to obtain the particles with smaller sizes. The XRD data demonstrated that the surfactants restrained the crystal growth of the grains. The nanoparticles showed superior magnetic properties and high colloidal stability in water. The cytotoxicity results indicated the feasibility of using the synthesized nanocrystals in biology-related fields. To estimate the applicability of the obtained MNCs in biotechnology, Candida rugosa lipase was selected for the enzyme immobilization process. The immobilized lipase exhibited excellent thermal stability and reusability in comparison with the free enzyme. This novel strategy would simplify the reaction protocol and improve the efficiency of materials functionalization, thus offering new potential applications in biotechnology and organocatalysis. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Biological functionalization of drug delivery carriers to bypass size restrictions of receptor-mediated endocytosis independently from receptor targeting.

    Science.gov (United States)

    Ansar, Maria; Serrano, Daniel; Papademetriou, Iason; Bhowmick, Tridib Kumar; Muro, Silvia

    2013-12-23

    Targeting of drug carriers to cell-surface receptors involved in endocytosis is commonly used for intracellular drug delivery. However, most endocytic receptors mediate uptake via clathrin or caveolar pathways associated with ≤200-nm vesicles, restricting carrier design. We recently showed that endocytosis mediated by intercellular adhesion molecule 1 (ICAM-1), which differs from clathrin- and caveolae-mediated pathways, allows uptake of nano- and microcarriers in cell culture and in vivo due to recruitment of cellular sphingomyelinases to the plasmalemma. This leads to ceramide generation at carrier binding sites and formation of actin stress-fibers, enabling engulfment and uptake of a wide size-range of carriers. Here we adapted this paradigm to enhance uptake of drug carriers targeted to receptors associated with size-restricted pathways. We coated sphingomyelinase onto model (polystyrene) submicro- and microcarriers targeted to clathrin-associated mannose-6-phosphate receptor. In endothelial cells, this provided ceramide enrichment at the cell surface and actin stress-fiber formation, modifying the uptake pathway and enhancing carrier endocytosis without affecting targeting, endosomal transport, cell-associated degradation, or cell viability. This improvement depended on the carrier size and enzyme dose, and similar results were observed for other receptors (transferrin receptor) and cell types (epithelial cells). This phenomenon also enhanced tissue accumulation of carriers after intravenous injection in mice. Hence, it is possible to maintain targeting toward a selected receptor while bypassing natural size restrictions of its associated endocytic route by functionalization of drug carriers with biological elements mimicking the ICAM-1 pathway. This strategy holds considerable promise to enhance flexibility of design of targeted drug delivery systems.

  6. Physicochemical characterization of Capstone depleted uranium aerosols I: uranium concentration in aerosols as a function of time and particle size.

    Science.gov (United States)

    Parkhurst, Mary Ann; Cheng, Yung Sung; Kenoyer, Judson L; Traub, Richard J

    2009-03-01

    During the Capstone Depleted Uranium (DU) Aerosol Study, aerosols containing DU were produced inside unventilated armored vehicles (i.e., Abrams tanks and Bradley Fighting Vehicles) by perforation with large-caliber DU penetrators. These aerosols were collected and characterized, and the data were subsequently used to assess human health risks to personnel exposed to DU aerosols. The DU content of each aerosol sample was first quantified by radioanalytical methods, and selected samples, primarily those from the cyclone separator grit chambers, were analyzed radiochemically. Deposition occurred inside the vehicles as particles settled on interior surfaces. Settling rates of uranium from the aerosols were evaluated using filter cassette samples that collected aerosol as total mass over eight sequential time intervals. A moving filter was used to collect aerosol samples over time, particularly within the first minute after a shot. The results demonstrate that the peak uranium concentration in the aerosol occurred in the first 10 s after perforation, and the concentration decreased in the Abrams tank shots to about 50% within 1 min and to less than 2% after 30 min. The initial and maximum uranium concentrations were lower in the Bradley vehicle than those observed in the Abrams tank, and the concentration levels decreased more slowly. Uranium mass concentrations in the aerosols as a function of particle size were evaluated using samples collected in a cyclone sampler, which collected aerosol continuously for 2 h after perforation. The percentages of uranium mass in the cyclone separator stages ranged from 38 to 72% for the Abrams tank with conventional armor. In most cases, it varied with particle size, typically with less uranium associated with the smaller particle sizes. Neither the Abrams tank with DU armor nor the Bradley vehicle results were specifically correlated with particle size and can best be represented by their average uranium mass concentrations of 65

  7. Molecular anatomy of interendothelial junctions in human blood-brain barrier microvessels.

    Directory of Open Access Journals (Sweden)

    Andrzej W Vorbrodt

    2004-07-01

    Full Text Available Immunogold cytochemical procedure was used to study the localization at the ultrastructural level of interendothelial junction-associated protein molecules in the human brain blood microvessels, representing the anatomic site of the blood-brain barrier (BBB. Ultrathin sections of Lowicryl K4M-embedded biopsy specimens of human cerebral cortex obtained during surgical procedures were exposed to specific antibodies, followed by colloidal gold-labeled secondary antibodies. All tight junction-specific integral membrane (transmembrane proteins--occludin, junctional adhesion molecule (JAM-1, and claudin-5--as well as peripheral zonula occludens protein (ZO-1 were highly expressed. Immunoreactivity of the adherens junction-specific transmembrane protein VE-cadherin was of almost similar intensity. Immunolabeling of the adherens junction-associated peripheral proteins--alpha-catenin, beta-catenin, and p120 catenin--although positive, was evidently less intense. The expression of gamma-catenin (plakoglobin was considered questionable because solitary immunosignals (gold particles appeared in only a few microvascular profiles. Double labeling of some sections made possible to observe strict colocalization of the junctional molecules, such as occludin and ZO-1 or JAM-1 and VE-cadherin, in the interendothelial junctions. We found that in human brain microvessels, the interendothelial junctional complexes contain molecular components specific for both tight and adherens junctions. It is assumed that the data obtained can help us find the immunodetectable junctional molecules that can serve as sensitive markers of normal or abnormal function of the BBB.

  8. Gap junctions are selectively associated with interlocking ball-and-sockets but not protrusions in the lens.

    Science.gov (United States)

    Biswas, Sondip K; Lee, Jai Eun; Brako, Lawrence; Jiang, Jean X; Lo, Woo-Kuen

    2010-11-09

    Ball-and-sockets and protrusions are specialized interlocking membrane domains between lens fibers of all species studied. Ball-and-sockets and protrusions are similar in their shape, size, and surface morphology, and are traditionally believed to play a key role in maintaining fiber-to-fiber stability. Here, we evaluate the hypothesis that ball-and-sockets and protrusions possess important structural and functional differences during fiber cell differentiation and maturation. Intact lenses of leghorn chickens (E7 days to P62 weeks old) and rhesus monkeys (1.5-20 years old) were studied with SEM, freeze-fracture TEM, freeze-fracture immunogold labeling (FRIL), and filipin cytochemistry for membrane cholesterol detection. SEM showed that ball-and-sockets were distributed along the long and short sides of hexagonal fiber cells, whereas protrusions were located along the cell corners, from superficial to deep cortical regions in both chicken and monkey lenses. Importantly, by freeze-fracture TEM, we discovered the selective association of gap junctions with all ball-and-sockets examined, but not with protrusions, in both species. In the embryonic chicken lens (E18), the abundant distribution of ball-and-socket gap junctions was regularly found in an approximate zone extending at least 300 μm deep from the equatorial surface of the superficial cortical fibers. Many ball-and-socket gap junctions often protruded deeply into neighboring cells. However, in the mature fibers of monkey lenses, several ball-and-sockets exhibited only partial occupancy of gap junctions with disorganized connexons, possibly due to degradation of gap junctions during fiber maturation and aging. FRIL analysis confirmed that both connexin46 (Cx46) and connexin50 (Cx50) antibodies specifically labeled ball-and-socket gap junctions, but not protrusions. Furthermore, filipin cytochemistry revealed that the ball-and-socket gap junctions contained different amounts of cholesterol (i.e., cholesterol

  9. Linking Tropical Forest Function to Hydraulic Traits in a Size-Structured and Trait-Based Model

    Science.gov (United States)

    Christoffersen, B. O.; Gloor, M.; Fauset, S.; Fyllas, N.; Galbraith, D.; Baker, T. R.; Rowland, L.; Fisher, R.; Binks, O.; Sevanto, S.; Xu, C.; Jansen, S.; Choat, B.; Mencuccini, M.; McDowell, N. G.; Meir, P.

    2015-12-01

    A major weakness of forest ecosystem models is their inability to capture the diversity of responses to changes in water availability, severely hampering efforts to predict the fate of tropical forests under climate change. Such models often prescribe moisture sensitivity using heuristic response functions that are uniform across all individuals and lack important knowledge about trade-offs in hydraulic traits. We address this weakness by implementing a process representation of plant hydraulics into an individual- and trait-based model (Trait Forest Simulator; TFS) intended for application at discrete sites where community-level distributions of stem and leaf trait spectra (wood density, leaf mass per area, leaf nitrogen and phosphorus content) are known. The model represents a trade-off in the safety and efficiency of water conduction in xylem tissue through hydraulic traits, while accounting for the counteracting effects of increasing hydraulic path length and xylem conduit taper on whole-plant hydraulic resistance with increasing tree size. Using existing trait databases and additional meta-analyses from the rich literature on tropical tree ecophysiology, we obtained all necessary hydraulic parameters associated with xylem conductivity, vulnerability curves, pressure-volume curves, and hydraulic architecture (e.g., leaf-to-sapwood area ratios) as a function of the aforementioned traits and tree size. Incorporating these relationships in the model greatly improved the diversity of tree response to seasonal changes in water availability as well as in response to drought, as determined by comparison with field observations and experiments. Importantly, this individual- and trait-based framework provides a testbed for identifying both critical processes and functional traits needed for inclusion in coarse-scale Dynamic Global Vegetation Models, which will lead to reduced uncertainty in the future state of tropical forests.

  10. Activation of the Small GTPase Rap1 Inhibits Choroidal Neovascularization by Regulating Cell Junctions and ROS Generation in Rats.

    Science.gov (United States)

    Li, Jiajia; Zhang, Rong; Wang, Caixia; Wang, Xin; Xu, Man; Ma, Jingxue; Shang, Qingli

    2018-03-30

    Choroidal neovascularization (CNV) is a common vision-threatening complication associated with many  fundus diseases. The retinal pigment epithelial (RPE) cell junction barrier has critical functions in preventing CNV, and oxidative stress can cause compromise of barrier integrity and induce angiogenesis. Rap1, a small guanosine triphosphatase (GTPase), is involved in regulating endothelial and epithelial cell junctions. In this work, we explored the function and mechanism of Rap1 in CNV in vivo. A laser-induced rat CNV model was developed. Rap1 was activated through intravitreal injection of the Rap1 activator 8CPT-2'-O-Me-cAMP (8CPT). At 14 days after laser treatment, CNV size in RPE/choroid flat mounts was measured by fluorescein isothiocyanate-dextran staining. Expression of vascular endothelial growth factor (VEGF) and cell junction proteins in RPE/choroid tissues were analyzed by western blots and quantitative real-time PCR assays. Reactive oxygen species (ROS) in RPE cells were detectedbydichloro-dihydro-fluorescein diacetate assays. The antioxidant apocynin was intraperitoneally injected into rats. Activating Rap1 by 8CPT significantly reduced CNV size and VEGF expression in the rat CNV model. Rap1 activation enhanced protein and mRNA levels of ZO-1 and occludin, two tight junction proteins in the RPE barrier. In addition, reducing ROS generation by injection of apocynin, a NADPH oxidase inhibitor, inhibited CNV formation. Rap1 activation reduced ROS generation and expression of NADPH oxidase 4. Rap1 activation inhibits CNV through regulating barrier integrity and ROS generation of RPE in vivo, and selectively activating Rap1 may be a way to reduce vision loss from CNV.

  11. Negative Differential Resistance in Atomic Carbon Chain-Graphene Junctions

    International Nuclear Information System (INIS)

    An Liping; Liu Chunmei; Liu Nianhua

    2012-01-01

    We investigate the electronic transport properties of atomic carbon chain-graphene junctions by using the density-functional theory combining with the non-equilibrium Green's functions. The results show that the transport properties are sensitively dependent on the contact geometry of carbon chain. From the calculated I-V curve we find negative differential resistance (NDR) in the two types of junctions. The NDR can be considered as a result of molecular orbitals moving related to the bias window. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  12. In situ observations of meteor smoke particles (MSP during the Geminids 2010: constraints on MSP size, work function and composition

    Directory of Open Access Journals (Sweden)

    M. Rapp

    2012-12-01

    three lamp types. Taking into account these data along with simple model estimates as well as rigorous quantum chemical calculations, it is argued that constraints on MSP sizes, work function and composition can be inferred. Comparing the measured data to a simple model of the photoelectron currents, we tentatively conclude that we observed MSPs in the 0.5–3 nm size range with generally increasing particle size with decreasing altitude. Notably, this size information can be obtained because different MSP particle sizes are expected to result in different work functions which is both supported by simple classical arguments as well as quantum chemical calculations. Based on this, the MSP work function can be estimated to lie in the range from ~4–4.6 eV. Finally, electronic structure calculations indicate that the low work function of the MSP measured by ECOMA indicates that Fe and Mg hydroxide clusters, rather than metal silicates, are the major constituents of the smoke particles.

  13. Measurement of noise in YBCO bi-crystal junctions

    International Nuclear Information System (INIS)

    Kuznik, J.; Hao, L.; Macfarlane, J.C.; Pegrum, C.M.; Fischer, G.M.; Mygind, J.; Pedersen, N.F.; Beck, A.; Gross, R.

    1993-01-01

    This paper describes collaborative work between three institutions as part of an ESPRIT programme to fabricate and characterise grain-boundary junctions. Bi-crystal junctions were fabricated at Tuebingen on SrTiO 3 substrates with a 24 misorientation angle and a-b tilt. 200nm of c-axis YBCO was sputter-deposited using a hollow-cathode magnetron, and the films patterned with optical lithography and Ar ion beam etching (3). For test purposes junctions with a range of sizes were made, with widths between 4 and 20μm. These have been characterised for noise properties at 0.3 - 1kHz and 60kHz at Strathclyde, and at 70GHz at Lyngby. (orig.)

  14. Coherence in a transmon qubit with epitaxial tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Weides, Martin [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Karlsruhe Institute of Technology (Germany); Kline, Jeffrey; Vissers, Michael; Sandberg, Martin; Pappas, David [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Wisbey, David [National Institute of Standards and Technology, Boulder, Colorado 80305 (United States); Saint Louis University, St. Louis, Missouri 63103 (United States); Johnson, Blake; Ohki, Thomas [Raytheon BBN Technologies, Cambridge, Massachusetts 02138 (United States)

    2012-07-01

    Transmon qubits based on epitaxial tunnel junctions and interdigitated capacitors were developed. This multileveled qubit, patterned by use of all-optical lithography, is a step towards scalable qubits with a high integration density. The relaxation time T{sub 1} is.72-.86 {mu} sec and the ensemble dephasing time T{sub 2}{sup *} is slightly larger than T{sub 1}. The dephasing time T{sub 2} (1.36 {mu} sec) is nearly energy-relaxation-limited. Qubit spectroscopy yields weaker level splitting than observed in qubits with amorphous barriers in equivalent-size junctions. The qubit's inferred microwave loss closely matches the weighted losses of the individual elements (junction, wiring dielectric, and interdigitated capacitor), determined by independent resonator measurements.

  15. Thermopower in double planar tunnel junctions with ferromagnetic barriers and nonmagnetic electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Wilczyński, M., E-mail: wilczyns@if.pw.edu.pl

    2017-01-01

    The Seebeck effect is investigated in double planar tunnel junctions consisting of nonmagnetic electrodes and the central layer separated by ferromagnetic barriers. Calculations are performed in the linear response theory using the free-electron model. The thermopower is analyzed as a function of the thickness of the central layer, temperature of the junctions and the relative orientation of magnetic moments of the barriers. It has been found that the thermopower can be significantly enhanced in the junction with special central layer thickness due to electron tunneling by resonant states. The thickness of the central layer for which the thermopower is enhanced depends not only on the temperature of the junction but also on the orientation of magnetic moments in the barriers. - Highlights: • Thermopower in the double planar junctions with magnetic barriers is analyzed. • Thermopower can be enhanced due to the resonant tunneling. • Thermopower depends on the magnetic configuration of the junction.

  16. Transition voltages of vacuum-spaced and molecular junctions with Ag and Pt electrodes

    KAUST Repository

    Wu, Kunlin; Bai, Meilin; Sanvito, Stefano; Hou, Shimin

    2014-01-01

    The transition voltage of vacuum-spaced and molecular junctions constructed with Ag and Pt electrodes is investigated by non-equilibrium Green's function formalism combined with density functional theory. Our calculations show that, similarly

  17. Impact of variety type and particle size distribution on starch enzymatic hydrolysis and functional properties of tef flours.

    Science.gov (United States)

    Abebe, Workineh; Collar, Concha; Ronda, Felicidad

    2015-01-22

    Tef grain is becoming very attractive in the Western countries since it is a gluten-free grain with appreciated nutritional advantages. However there is little information of its functional properties and starch digestibility and how they are affected by variety type and particle size distribution. This work evaluates the effect of the grain variety and the mill used on tef flour physico-chemical and functional properties, mainly derived from starch behavior. In vitro starch digestibility of the flours by Englyst method was assessed. Two types of mills were used to obtain whole flours of different granulation. Rice and wheat flours were analyzed as references. Protein molecular weight distribution and flour structure by SEM were also analyzed to justify some of the differences found among the cereals studied. Tef cultivar and mill type exhibited important effect on granulation, bulking density and starch damage, affecting the processing performance of the flours and determining the hydration and pasting properties. The color was darker although one of the white varieties had a lightness near the reference flours. Different granulation of tef flour induced different in vitro starch digestibility. The disc attrition mill led to higher starch digestibility rate index and rapidly available glucose, probably as consequence of a higher damaged starch content. The results confirm the adequacy of tef flour as ingredient in the formulation of new cereal based foods and the importance of the variety and the mill on its functional properties. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. Estimating the population size and colony boundary of subterranean termites by using the density functions of directionally averaged capture probability.

    Science.gov (United States)

    Su, Nan-Yao; Lee, Sang-Hee

    2008-04-01

    Marked termites were released in a linear-connected foraging arena, and the spatial heterogeneity of their capture probabilities was averaged for both directions at distance r from release point to obtain a symmetrical distribution, from which the density function of directionally averaged capture probability P(x) was derived. We hypothesized that as marked termites move into the population and given sufficient time, the directionally averaged capture probability may reach an equilibrium P(e) over the distance r and thus satisfy the equal mixing assumption of the mark-recapture protocol. The equilibrium capture probability P(e) was used to estimate the population size N. The hypothesis was tested in a 50-m extended foraging arena to simulate the distance factor of field colonies of subterranean termites. Over the 42-d test period, the density functions of directionally averaged capture probability P(x) exhibited four phases: exponential decline phase, linear decline phase, equilibrium phase, and postequilibrium phase. The equilibrium capture probability P(e), derived as the intercept of the linear regression during the equilibrium phase, correctly projected N estimates that were not significantly different from the known number of workers in the arena. Because the area beneath the probability density function is a constant (50% in this study), preequilibrium regression parameters and P(e) were used to estimate the population boundary distance 1, which is the distance between the release point and the boundary beyond which the population is absent.

  19. The Effects of Glucagon-like Peptide-2 on the Tight Junction and Barrier Function in IPEC-J2 Cells through Phosphatidylinositol 3-kinase–Protein Kinase B–Mammalian Target of Rapamycin Signaling Pathway

    Directory of Open Access Journals (Sweden)

    Changsong Yu

    2016-05-01

    Full Text Available Glucagon-like peptide-2 (GLP-2 is important for intestinal barrier function and regulation of tight junction (TJ proteins, but the intracellular mechanisms of action remain undefined. The purpose of this research was to determine the protective effect of GLP-2 mediated TJ and transepithelial electrical resistance (TER in lipopolysaccharide (LPS stressed IPEC-J2 cells and to test the hypothesis that GLP-2 regulate TJ and TER through the phosphatidylinositol 3-kinase (PI3K-protein kinase B (Akt-mammalian target of rapamycin (mTOR signaling pathway in IPEC-J2 cells. Wortmannin and LY294002 are specific inhibitors of PI3K. The results showed that 100 μg/mL LPS stress decreased TER and TJ proteins occludin, claudin-1 and zonula occludens protein 1 (ZO-1 mRNA, proteins expressions (p<0.01 respectively. GLP-2 (100 nmol/L promote TER and TJ proteins occludin, claudin-1, and zo-1 mRNA, proteins expressions in LPS stressed and normal IPEC-J2 cells (p<0.01 respectively. In normal cells, both wortmannin and LY294002, PI3K inhibitors, prevented the mRNA and protein expressions of Akt and mTOR increase induced by GLP-2 (p<0.01 following with the significant decreasing of occludin, claudin-1, ZO-1 mRNA and proteins expressions and TER (p<0.01. In conclusion, these results indicated that GLP-2 can promote TJ’s expression and TER in LPS stressed and normal IPEC-J2 cells and GLP-2 could regulate TJ and TER through the PI3K/Akt/mTOR pathway.

  20. The distribution of work performed on a NIS junction

    DEFF Research Database (Denmark)

    Santos, Jaime Eduardo Vieira da Silva Moutinho; Ribeiro, Pedro; Kirchner, Stefan

    2016-01-01

    We propose an experimental setup to measure the work performed in a normal-metal/insulator/superconducting (NIS) junction, subjected to a voltage change and in contact with a thermal bath. We compute the performed work and argue that the associated heat release can be measured experimentally. Our...... results are based on an equivalence between the dynamics of the NIS junction and that of an assembly of two-level systems subjected to a circularly polarised field, for which we can determine the work-characteristic function exactly. The average work dissipated by the NIS junction, as well as its...... fluctuations, are determined. From the work characteristic function, we also compute the work probability-distribution and show that it does not have a Gaussian character. Our results allow for a direct experimental test of the Crooks–Tasaki fluctuation relation....

  1. The distribution of work performed on a NIS junction

    International Nuclear Information System (INIS)

    Santos, Jaime E; Ribeiro, Pedro; Kirchner, Stefan

    2016-01-01

    We propose an experimental setup to measure the work performed in a normal-metal/insulator/superconducting (NIS) junction, subjected to a voltage change and in contact with a thermal bath. We compute the performed work and argue that the associated heat release can be measured experimentally. Our results are based on an equivalence between the dynamics of the NIS junction and that of an assembly of two-level systems subjected to a circularly polarised field, for which we can determine the work-characteristic function exactly. The average work dissipated by the NIS junction, as well as its fluctuations, are determined. From the work characteristic function, we also compute the work probability-distribution and show that it does not have a Gaussian character. Our results allow for a direct experimental test of the Crooks–Tasaki fluctuation relation. (paper)

  2. NbN tunnel junctions

    International Nuclear Information System (INIS)

    Villegier, J.C.; Vieux-Rochaz, L.; Goniche, M.; Renard, P.; Vabre, M.

    1984-09-01

    All-niobium nitride Josephon junctions have been prepared successfully using a new processing called SNOP: Selective Niobium (nitride) Overlap Process. Such a process involves the ''trilayer'' deposition on the whole wafer before selective patterning of the electrodes by optically controlled dry reactive ion etching. Only two photomask levels are need to define an ''overlap'' or a ''cross-type'' junction with a good accuracy. The properties of the niobium nitride films deposited by DC-magnetron sputtering and the surface oxide growth are analysed. The most critical point to obtain high quality and high gap value junctions resides in the early stage of the NbN counterelectrode growth. Some possibilities to overcome such a handicap exist even if the fabrication needs substrate temperatures below 250 0 C

  3. Effect of silica nanoparticles with variable size and surface functionalization on human endothelial cell viability and angiogenic activity

    Science.gov (United States)

    Guarnieri, Daniela; Malvindi, Maria Ada; Belli, Valentina; Pompa, Pier Paolo; Netti, Paolo

    2014-02-01

    Silica nanoparticles could be promising delivery vehicles for drug targeting or gene therapy. However, few studies have been undertaken to determine the biological behavior effects of silica nanoparticles on primary endothelial cells. Here we investigated uptake, cytotoxicity and angiogenic properties of silica nanoparticle with positive and negative surface charge and sizes ranging from 25 to 115 nm in primary human umbilical vein endothelial cells. Dynamic light scattering measurements and nanoparticle tracking analysis were used to estimate the dispersion status of nanoparticles in cell culture media, which was a key aspect to understand the results of the in vitro cellular uptake experiments. Nanoparticles were taken up by primary endothelial cells in a size-dependent manner according to their degree of agglomeration occurring after transfer in cell culture media. Functionalization of the particle surface with positively charged groups enhanced the in vitro cellular uptake, compared to negatively charged nanoparticles. However, this effect was contrasted by the tendency of particles to form agglomerates, leading to lower internalization efficiency. Silica nanoparticle uptake did not affect cell viability and cell membrane integrity. More interestingly, positively and negatively charged 25 nm nanoparticles did not influence capillary-like tube formation and angiogenic sprouting, compared to controls. Considering the increasing interest in nanomaterials for several biomedical applications, a careful study of nanoparticle-endothelial cells interactions is of high relevance to assess possible risks associated to silica nanoparticle exposure and their possible applications in nanomedicine as safe and effective nanocarriers for vascular transport of therapeutic agents.

  4. Highlights from the Functional Single Nucleotide Polymorphisms Associated with Human Muscle Size and Strength or FAMuSS Study

    Directory of Open Access Journals (Sweden)

    Linda S. Pescatello

    2013-01-01

    Full Text Available The purpose of the Functional Single Nucleotide Polymorphisms Associated with Human Muscle Size and Strength study or FAMuSS was to identify genetic factors that dictated the response of health-related fitness phenotypes to resistance exercise training (RT. The phenotypes examined were baseline muscle strength and muscle, fat, and bone volume and their response to RT. FAMuSS participants were 1300 young (24 years, healthy men (42% and women (58% that were primarily of European-American descent. They were genotyped for ~500 polymorphisms and completed the Paffenbarger Physical Activity Questionnaire to assess energy expenditure and time spent in light, moderate, and vigorous intensity habitual physical activity and sitting. Subjects then performed a 12-week progressive, unilateral RT program of the nondominant arm with the dominant arm used as a comparison. Before and after RT, muscle strength was measured with the maximum voluntary contraction and one repetition maximum, while MRI measured muscle, fat, and bone volume. We will discuss the history of how FAMuSS originated, provide a brief overview of the FAMuSS methods, and summarize our major findings regarding genotype associations with muscle strength and size, body composition, cardiometabolic biomarkers, and physical activity.

  5. Size-dependent electro-magneto-elastic bending analyses of the shear-deformable axisymmetric functionally graded circular nanoplates

    Science.gov (United States)

    Arefi, Mohammad; Zenkour, Ashraf M.

    2017-10-01

    This paper develops nonlocal elasticity equations and magneto-electro-elastic relations to size-dependent electro-magneto-elastic bending analyses of the functionally graded axisymmetric circular nanoplates based on the first-order shear deformation theory. All material properties are graded along the thickness direction based on exponential varying. It is assumed that a circular nanoplate is made from piezo-magnetic materials. The energy method and Ritz approach is employed for the derivation of governing equations of electro-magneto-elastic bending and the solution of the problem, respectively. The nanoplate is subjected to applied electric and magnetic potentials at top and transverse loads while it is rested on Pasternak's foundation. Some important numerical results are presented in various figures to show the influence of applied electric and magnetic potentials, small scale parameter and inhomogeneous index of an exponentially graded nanoplate.

  6. Limitation of myocardial infarct size and preservation of left ventricular function by early administration of APSAC in myocardial infarction.

    Science.gov (United States)

    Bassand, J P; Machecourt, J; Cassagnes, J; Lusson, J R; Borel, E; Schiele, F

    1989-07-05

    In cases of acute myocardial infarction (MI), it has been shown that preserving left ventricular function and limiting infarct size with early reperfusion of the occluded artery by means of a thrombolytic agent could eventually result in a reduced mortality rate. The aim of the APSIM study (anisoylated plasminogen streptokinase activator complex [APSAC] dans l'infarctus du Myocarde) was to demonstrate that early administration of APSAC in patients with recent acute MI could limit the infarct size and preserve left ventricular systolic function. In all, 231 patients with a first acute MI were randomly allocated to either APSAC (30 U over 5 minutes) or to conventional heparin therapy (5,000 IU in bolus injection) within 5 hours of the onset of symptoms. Of these patients, 112 received APSAC and 119 received heparin within a mean period of 188 +/- 62 minutes after the onset of symptoms. The patency rate of the infarct-related artery was 77% in the APSAC group and 36% in the heparin group (p less than 0.001). Left ventricular ejection fraction determined from contrast angiography was significantly higher in the APSAC than in the heparin group. This was true for the entire population (0.53 +/- 0.13 vs 0.47 +/- 0.13, p = 0.002) as well as for the subgroups of anterior and inferior wall infarctions (0.47 +/- 0.13 vs 0.4 +/- 0.16, p = 0.004 and 0.56 +/- 0.11 vs 0.51 +/- 0.09, p = 0.02). At 3 weeks, the difference remained significant for patients with anterior MI.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Grain boundary and triple junction diffusion in nanocrystalline copper

    Energy Technology Data Exchange (ETDEWEB)

    Wegner, M., E-mail: m.wegner@uni-muenster.de; Leuthold, J.; Peterlechner, M.; Divinski, S. V., E-mail: divin@uni-muenster.de [Institut für Materialphysik, Universität Münster, Wilhelm-Klemm-Straße 10, D-48149, Münster (Germany); Song, X., E-mail: xysong@bjut.edu.cn [College of Materials Science and Engineering, Beijing University of Technology, 100124 Beijing (China); Wilde, G. [Institut für Materialphysik, Universität Münster, Wilhelm-Klemm-Straße 10, D-48149, Münster (Germany); Institute of Nanochemistry and Nanobiology, School of Environmental and Chemical Engineering, Shanghai University, 200444 Shanghai (China)

    2014-09-07

    Grain boundary and triple junction diffusion in nanocrystalline Cu samples with grain sizes, 〈d〉, of ∼35 and ∼44 nm produced by spark plasma sintering were investigated by the radiotracer method using the {sup 63}Ni isotope. The measured diffusivities, D{sub eff}, are comparable with those determined previously for Ni grain boundary diffusion in well-annealed, high purity, coarse grained, polycrystalline copper, substantiating the absence of a grain size effect on the kinetic properties of grain boundaries in a nanocrystalline material at grain sizes d ≥ 35 nm. Simultaneously, the analysis predicts that if triple junction diffusion of Ni in Cu is enhanced with respect to the corresponding grain boundary diffusion rate, it is still less than 500⋅D{sub gb} within the temperature interval from 420 K to 470 K.

  8. P-N semiconductor junctions used as X-ray detectors

    International Nuclear Information System (INIS)

    Pela, C.A.; Bruco, J.L.; Navas, E.A.; Paula, E. de; Guilardi Neto, T.

    1987-01-01

    The current response of some comercial P-N semiconductor junctions in function of X-ray incidency, in 40 to 140 KVp band used in diagnosis was characterized. Some junctions were also exposed to radiation of 80 to 250 KVp used in therapy. (C.G.C.) [pt

  9. Gravitation at the Josephson Junction

    Directory of Open Access Journals (Sweden)

    Victor Atanasov

    2018-01-01

    Full Text Available A geometric potential from the kinetic term of a constrained to a curved hyperplane of space-time quantum superconducting condensate is derived. An energy conservation relation involving the geometric field at every material point in the superconductor is demonstrated. At a Josephson junction the energy conservation relation implies the possibility of transforming electric energy into geometric field energy, that is, curvature of space-time. Experimental procedures to verify that the Josephson junction can act as a voltage-to-curvature converter are discussed.

  10. impairs gap junction function causing congenital cataract

    Indian Academy of Sciences (India)

    Navya

    2017-03-24

    Mar 24, 2017 ... ... applied to analyze the expression and subcellular localization of recombinant ... Cx46. The fluorescent localization assay revealed the plaque formation ... composed of six trans-membrane protein subunits called connexins ...

  11. Gold removal rate by ion sputtering as a function of ion-beam voltage and raster size using Auger electron spectroscopy. Final report

    International Nuclear Information System (INIS)

    Boehning, C.W.

    1983-01-01

    Gold removal rate was measured as a function of ion beam voltage and raster size using Auger electron spectroscopy (AES). Three different gold thicknesses were developed as standards. Two sputter rate calibration curves were generated by which gold sputter rate could be determined for variations in ion beam voltage or raster size

  12. Electrochemically assisted mechanically controllable break junction studies on the stacking configurations of oligo(phenylene ethynylene)s molecular junctions

    International Nuclear Information System (INIS)

    Zheng, Jue-Ting; Yan, Run-Wen; Tian, Jing-Hua; Liu, Jun-Yang; Pei, Lin-Qi; Wu, De-Yin; Dai, Ke; Yang, Yang; Jin, Shan

    2016-01-01

    Highlights: • I-V characteristics of a series of oligo(phenylene ethynylene)s molecular junctions were measured. • Conductance values were found to be dependent on molecular length and substituent group. • The measured low conductance values were explained by theoretical calculations. • EC-MCBJ is feasible to fabricate and characterize molecular junctions. - Abstract: We demonstrate an electrochemically assisted mechanically controllable break junction (EC-MCBJ) approach for current-voltage characteristic (I-V curve) measurements of metal/molecule/metal junctions. A series of oligo(phenylene ethynylene)s compounds (OPEs), including those involving electron withdrawing substituent group and different backbone lengths, had been successfully designed, synthesized, and placed onto the fabricated nanogap to form molecular junctions. The observed evolution in the measured conductances of OPEs indicates that there is a dependence of conductance on molecular length and substituent group. Compared with those extracted from conductance histogram construction, the conductances of OPEs measured from I-V curves are considerably lower. Based on the transmission spectra of OPEs that calculated by density functional theory (DFT) combined with non-equilibrium Green’s function (NEGF) method, this difference was attributed to our distinct experimental operation, which may give rise to a stacking configuration of two OPE molecules.

  13. Eco-friendly synthesis of size-controllable amine-functionalized graphene quantum dots with antimycoplasma properties.

    Science.gov (United States)

    Jiang, Feng; Chen, Daiqin; Li, Ruimin; Wang, Yucheng; Zhang, Guoqiang; Li, Shumu; Zheng, Junpeng; Huang, Naiyan; Gu, Ying; Wang, Chunru; Shu, Chunying

    2013-02-07

    Size-controllable amine-functionalized graphene quantum dots (GQDs) are prepared by an eco-friendly method with graphene oxide sheets, ammonia and hydrogen peroxide as starting materials. Using a Sephadex G-25 gel column for fine separation, for the first time we obtain GQDs with either single or double layers. By atomic force microscopy characterization, we confirm that hydrogen peroxide and ammonia play a synergistic role on graphene oxide (GO), in which the former cuts the GO into small pieces and the latter passivates the active surface to give amine-modified GQDs. Due to the low cytotoxicity and excellent biocompatibility of the obtained amine-functionalized GQDs, besides the multiwavelength imaging properties of GQDs, for the first time we find that this kind of GQD exhibits good antimycoplasma properties. Given the superior antimycoplasma effect of the GQDs and their eco-friendly mass production with low cost, these new GQDs may offer opportunities for the development of new antimycoplasma agents, thus extending their widespread application in biomedicine.

  14. Cluster size statistic and cluster mass statistic: two novel methods for identifying changes in functional connectivity between groups or conditions.

    Science.gov (United States)

    Ing, Alex; Schwarzbauer, Christian

    2014-01-01

    Functional connectivity has become an increasingly important area of research in recent years. At a typical spatial resolution, approximately 300 million connections link each voxel in the brain with every other. This pattern of connectivity is known as the functional connectome. Connectivity is often compared between experimental groups and conditions. Standard methods used to control the type 1 error rate are likely to be insensitive when comparisons are carried out across the whole connectome, due to the huge number of statistical tests involved. To address this problem, two new cluster based methods--the cluster size statistic (CSS) and cluster mass statistic (CMS)--are introduced to control the family wise error rate across all connectivity values. These methods operate within a statistical framework similar to the cluster based methods used in conventional task based fMRI. Both methods are data driven, permutation based and require minimal statistical assumptions. Here, the performance of each procedure is evaluated in a receiver operator characteristic (ROC) analysis, utilising a simulated dataset. The relative sensitivity of each method is also tested on real data: BOLD (blood oxygen level dependent) fMRI scans were carried out on twelve subjects under normal conditions and during the hypercapnic state (induced through the inhalation of 6% CO2 in 21% O2 and 73%N2). Both CSS and CMS detected significant changes in connectivity between normal and hypercapnic states. A family wise error correction carried out at the individual connection level exhibited no significant changes in connectivity.

  15. Effects of pretreatment on the surface chemistry and pore size properties of nitrogen functionalized and alkylated granular activated carbon

    Energy Technology Data Exchange (ETDEWEB)

    Chen Jiajun [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Zhai Yunbo, E-mail: ybzhai@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Chen Hongmei; Li Caiting; Zeng Guangming; Pang Daoxiong; Lu Pei [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China)

    2012-12-15

    Highlights: Black-Right-Pointing-Pointer The effects of pretreatment on the surface chemistry and pore sizes were studied. Black-Right-Pointing-Pointer Treated GAC was nitrogen functionalized and alkylated GAC also called modified GAC. Black-Right-Pointing-Pointer HNO{sub 3} pretreatment caused a slight decrease in surface area and microporosity. Black-Right-Pointing-Pointer The nitrogen percentage of modified GAC which pretreated by H{sub 2}O{sub 2} was 4.07%. Black-Right-Pointing-Pointer The pyridine of modified GAC which pretreated by urea-formaldehyde resin was 45.88%. - Abstract: In this paper, granular activated carbon (GAC) from coconut shell was pretreated by HNO{sub 3}, H{sub 2}O{sub 2} and urea-formaldehyde resin, respectively. Then the obtained materials were functionalized in the same way for nitrogen group, and then alkylated. Effects of pretreatment on the surface chemistry and pore size of modified GACs were studied. Surface area and micropore volume of modified GAC which pretreated by HNO{sub 3} were 723.88 m{sup 2}/g and 0.229 cm{sup 3}/g, respectively, while virgin GAC were 742.34 m{sup 2}/g and 0.276 cm{sup 3}/g. Surface area and micropore volume decrease of the modified GACs which pretreated by the others two methods were more drastically. The types of groups presented were analyzed by electrophoresis, Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). N-CH{sub 3} group and C=N group were detected on the surfaces of these three kinds of modified GACs. Results of XPS showed that the nitrogen functions of modified GAC which pretreated by H{sub 2}O{sub 2} was 4.07%, it was more than that of the others two pretreatment methods. However, the modified GAC which pretreated by urea-formaldehyde resin was fixed more pyridine structure, which structure percentage was 45.88%, in addition, there were more basic groups or charge on the surface than the others.

  16. dc properties of series-parallel arrays of Josephson junctions in an external magnetic field

    International Nuclear Information System (INIS)

    Lewandowski, S.J.

    1991-01-01

    A detailed dc theory of superconducting multijunction interferometers has previously been developed by several authors for the case of parallel junction arrays. The theory is now extended to cover the case of a loop containing several junctions connected in series. The problem is closely associated with high-T c superconductors and their clusters of intrinsic Josephson junctions. These materials exhibit spontaneous interferometric effects, and there is no reason to assume that the intrinsic junctions form only parallel arrays. A simple formalism of phase states is developed in order to express the superconducting phase differences across the junctions forming a series array as functions of the phase difference across the weakest junction of the system, and to relate the differences in critical currents of the junctions to gaps in the allowed ranges of their phase functions. This formalism is used to investigate the energy states of the array, which in the case of different junctions are split and separated by energy barriers of height depending on the phase gaps. Modifications of the washboard model of a single junction are shown. Next a superconducting inductive loop containing a series array of two junctions is considered, and this model is used to demonstrate the transitions between phase states and the associated instabilities. Finally, the critical current of a parallel connection of two series arrays is analyzed and shown to be a multivalued function of the externally applied magnetic flux. The instabilities caused by the presence of intrinsic serial junctions in granular high-T c materials are pointed out as a potential source of additional noise

  17. Fabrication of sub-micron whole waffer SIS tunnel junctions for millimeter wave mixers

    International Nuclear Information System (INIS)

    Huq, S.E.; Blamire, M.G.; Evetts, J.E.; Hasko, D.G.; Ahmed, H.

    1991-01-01

    As a part of a programme for the development of a space-qualified sub-mm-wave mixer operating in the region of one terahertz we have been developing the processes required for the fabrication of submicron whole wafer tunnel junctions. Using the self-aligned whole-wafer process (SAWW) with electron beam lithography we have been able to reliably fabricate high quality (V m > 20 mV) submicron tunnel junctions from whole wafer Nb/AlO x /Nb structures. In particular we show that the junction quality is independent of size down to 0.3 μm 2 junction area. The problems of film stress, anodization, registration for electron beam lithography and lift-off, which limit the yield of good quality sub-micron scale junctions are addressed in this paper

  18. Charge Transport Processes in Molecular Junctions

    Science.gov (United States)

    Smith, Christopher Eugene

    Molecular electronics (ME) has evolved into a rich area of exploration that combines the fields of chemistry, materials, electronic engineering and computational modeling to explore the physics behind electronic conduction at the molecular level. Through studying charge transport properties of single molecules and nanoscale molecular materials the field has gained the potential to bring about new avenues for the miniaturization of electrical components where quantum phenomena are utilized to achieve solid state molecular device functionality. Molecular junctions are platforms that enable these studies and consist of a single molecule or a small group of molecules directly connected to electrodes. The work presented in this thesis has built upon the current understanding of the mechanisms of charge transport in ordered junctions using self-assembled monolayer (SAM) molecular thin films. Donor and acceptor compounds were synthesized and incorporated into SAMs grown on metal substrates then the transport properties were measured with conducting probe atomic force microscopy (CP-AFM). In addition to experimentally measured current-voltage (I-V) curves, the transport properties were addressed computationally and modeled theoretically. The key objectives of this project were to 1) investigate the impact of molecular structure on hole and electron charge transport, 2) understand the nature of the charge carriers and their structure-transport properties through long (chemically gated to modulate the transport. These results help advance our understanding of transport behavior in semiconducting molecular thin films, and open opportunities to engineer improved electronic functionality into molecular devices.

  19. Current noise in tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Frey, Moritz; Grabert, Hermann [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder-Strasse 3, 79104, Freiburg (Germany)

    2017-06-15

    We study current fluctuations in tunnel junctions driven by a voltage source. The voltage is applied to the tunneling element via an impedance providing an electromagnetic environment of the junction. We use circuit theory to relate the fluctuations of the current flowing in the leads of the junction with the voltage fluctuations generated by the environmental impedance and the fluctuations of the tunneling current. The spectrum of current fluctuations is found to consist of three parts: a term arising from the environmental Johnson-Nyquist noise, a term due to the shot noise of the tunneling current and a third term describing the cross-correlation between these two noise sources. Our phenomenological theory reproduces previous results based on the Hamiltonian model for the dynamical Coulomb blockade and provides a simple understanding of the current fluctuation spectrum in terms of circuit theory and properties of the average current. Specific results are given for a tunnel junction driven through a resonator. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  20. Expression pattern of adhesion molecules in junctional epithelium differs from that in other gingival epithelia.

    Science.gov (United States)

    Hatakeyama, S; Yaegashi, T; Oikawa, Y; Fujiwara, H; Mikami, T; Takeda, Y; Satoh, M

    2006-08-01

    The gingival epithelium is the physiologically important interface between the bacterially colonized gingival sulcus and periodontal soft and mineralized connective tissues, requiring protection from exposure to bacteria and their products. However, of the three epithelia comprising the gingival epithelium, the junctional epithelium has much wider intercellular spaces than the sulcular epithelium and oral gingival epithelium. Hence, the aim of the present study was to characterize the cell adhesion structure in the junctional epithelium compared with the other two epithelia. Gingival epithelia excised at therapeutic flap surgery from patients with periodontitis were examined for expression of adhesion molecules by immunofluorescence. In the oral gingival epithelium and sulcular epithelium, but not in the junctional epithelium, desmoglein 1 and 2 in cell-cell contact sites were more abundant in the upper than the suprabasal layers. E-cadherin, the main transmembranous molecule of adherens junctions, was present in spinous layers of the oral gingival epithelium and sulcular epithelium, but was scarce in the junctional epithelium. In contrast, desmoglein 3 and P-cadherin were present in all layers of the junctional epithelium as well as the oral gingival epithelium and sulcular epithelium. Connexin 43 was clearly localized to spinous layers of the oral gingival epithelium, sulcular epithelium and parts of the junctional epithelium. Claudin-1 and occludin were expressed in the cell membranes of a few superficial layers of the oral gingival epithelium. These findings indicated that the junctional epithelium contains only a few desmosomes, composed of only desmoglein 3; adherens junctions are probably absent because of defective E-cadherin. Thus, the anchoring junctions connecting junctional epithelium cells are lax, causing widened intercellular spaces. In contrast, the oral gingival epithelium, which has a few tight junctions, functions as a barrier.

  1. Chlorpromazine reduces the intercellular communication via gap junctions in mammalian cells

    International Nuclear Information System (INIS)

    Orellana, Juan A.; Palacios-Prado, Nicolas; Saez, Juan C.

    2006-01-01

    In the work presented herein, we evaluated the effect of chlorpromazine (CPZ) on gap junctions expressed by two mammalian cell types; Gn-11 cells (cell line derived from mouse LHRH neurons) and rat cortical astrocytes maintained in culture. We also attempted to elucidate possible mechanisms of action of CPZ effects on gap junctions. CPZ, in concentrations comparable with doses used to treat human diseases, was found to reduce the intercellular communication via gap junctions as evaluated with measurements of dye coupling (Lucifer yellow). In both cell types, maximal inhibition of functional gap junctions was reached within about 1 h of treatment with CPZ, an recovery was almost complete at about 5 h after CPZ wash out. In both cell types, CPZ treatment increased the phosphorylation state of connexin43 (Cx43), a gap junction protein subunit. Moreover, CPZ reduced the reactivity of Cx43 (immunofluorescence) at cell interfaces and concomitantly increased its reactivity in intracellular vesicles, suggesting an increased retrieval from and/or reduced insertion into the plasma membrane. CPZ also caused cellular retraction reducing cell-cell contacts in a reversible manner. The reduction in contact area might destabilize existing gap junctions and abrogate formation of new ones. Moreover, the CPZ-induced reduction in gap junctional communication may depend on the connexins (Cxs) forming the junctions. If Cx43 were the only connexin expressed, MAPK-dependent phosphorylation of this connexin would induce closure of gap junction channels

  2. Nonlinear electrical properties of Si three-terminal junction devices

    DEFF Research Database (Denmark)

    Fantao, Meng; Jie, Sun; Graczyk, Mariusz

    2010-01-01

    This letter reports on the realization and characterization of silicon three-terminal junction devices made in a silicon-on-insulator wafer. Room temperature electrical measurements show that the fabricated devices exhibit pronounced nonlinear electrical properties inherent to ballistic electron...... transport in a three-terminal ballistic junction (TBJ) device. The results show that room temperature functional TBJ devices can be realized in a semiconductor material other than high-mobility III-V semiconductor heterostructures and provide a simple design principle for compact silicon devices...

  3. Effects of junctions on carbon nanotube network-based devices

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Pil Soo; Kim, Gyu Tae [School of Electrical Engineering, Korea University, Seoul 136-713 (Korea, Republic of)

    2011-11-15

    Realistic random networks of carbon nanotubes (CNTs) were simulated by the noble hybrid method combining Monte Carlo and SPICE simulations. Near the percolation threshold, the electrical characteristics of networks are strongly affected by the contacts among nanotubes. The nonlinear electrical junctions in the CNT network were modeled by suitable SPICE models and simulated using our hybrid simulation method. We successfully described the morphological percolation threshold, and the critical density was determined as a function of normalized length. The effects of electrical junctions on the scaling of the sheet conductance were investigated. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Spin transport in spin filtering magnetic tunneling junctions.

    Science.gov (United States)

    Li, Yun; Lee, Eok Kyun

    2007-11-01

    Taking into account spin-orbit coupling and s-d interaction, we investigate spin transport properties of the magnetic tunneling junctions with spin filtering barrier using Landauer-Büttiker formalism implemented with the recursive algorithm to calculate the real-space Green function. We predict completely different bias dependence of negative tunnel magnetoresistance (TMR) between the systems composed of nonmagnetic electrode (NM)/ferromagnetic barrier (FB)/ferromagnet (FM) and NM/FB/FM/NM spin filtering tunnel junctions (SFTJs). Analyses of the results provide us possible ways of designing the systems which modulate the TMR in the negative magnetoresistance regime.

  5. Conformations of cyclopentasilane stereoisomers control molecular junction conductance

    DEFF Research Database (Denmark)

    Li, Haixing; Garner, Marc Hamilton; Shangguan, Zhichun

    2016-01-01

    ,3-position with methylthiomethyl electrode binding groups using both the scanning tunneling microscope-based break junction technique and density functional theory based ab initio calculations. In contrast with the linear ones, these cyclic silanes yield lower conductance values; calculations reveal...

  6. Microwave dependence of subharmonic gap structure in superconducting junctions

    DEFF Research Database (Denmark)

    Sørensen, O. Hoffman; Kofoed, Bent; Pedersen, Niels Falsig

    1974-01-01

    are integers: m=1,2,3,… and n=0,1,2,…. The power dependence of the satellite structure and the microwave-assisted tunneling structure is consistent for all junctions tested with the expression Jn2(m e Vrf / h ν), where Jn(x) is the ordinary Bessel function of order n, Vrf is the amplitude of the induced...

  7. Multiband model for tunneling in MgB2 junctions

    NARCIS (Netherlands)

    Brinkman, Alexander; Golubov, Alexandre Avraamovitch; Rogalla, Horst; Dolgov, O.V.; Kortus, J.; Kong, Y.; Jepsen, O.; Andersen, O.K.

    2002-01-01

    A theoretical model for quasiparticle and Josephson tunneling in multiband superconductors is developed and applied to MgB2-based junctions. The gap functions in different bands in MgB2 are obtained from an extended Eliashberg formalism, using the results of band structure calculations. The

  8. Bubbles and Dust: Dissolution Rates of Unhydrated Volcanic Ash as a Function of Morphology, Composition, and Particle Size

    Science.gov (United States)

    Wygel, C. M.; Sahagian, D. L.

    2017-12-01

    Volcanic eruptions are natural hazards due to their explosive nature and widespread transportation and deposition of ash particles. After deposition and subsequent leaching in soils or water bodies, ash deposition positively (nutrients) and negatively (contaminants) impacts the health of flora and fauna, including humans. The effects of ash leachates have been difficult to replicate in field and laboratory studies due to the many complexities and differences between ash particles. Ash morphology is characteristic for each eruption, dependent upon eruption energy, and should play a critical role in determining leaching rates. Morphology reflects overall particle surface area, which is strongly influenced by the presence of surface dust. In addition, ash composition, which in part controls morphology and particle size, may also affect leaching rates. This study determines the extent to which ash morphology, surface area, composition, and particle size control ash dissolution rates. Further, it is necessary to determine whether compound vesicular ash particles permit water into their interior structures to understand if both the internal and external surface areas are available for leaching. To address this, six fresh, unhydrated ash samples from diverse volcanic environments and a large range in morphology, from Pele's spheres to vesicular compound ash, are tested in the laboratory. Ash morphology was characterized on the Scanning Electron Microscope (SEM) before and after leaching and surface area was quantified by Brunauer Emmett Teller (BET) analysis and with geometric calculations. Column Leachate Tests (CLT) were conducted to compare leaching rates over a range of basaltic to silicic ashes as a function of time and surface area, to recreate the effects of ash deposition in diverse volcanic environments. After the CLT, post-leaching water analyses were conducted by Ion Coupled Plasma-Mass Spectrometry (ICP-MS) and Ion Chromatography (IC). We find that leaching

  9. Stability of large-area molecular junctions

    NARCIS (Netherlands)

    Akkerman, Hylke B.; Kronemeijer, Auke J.; Harkema, Jan; van Hal, Paul A.; Smits, Edsger C. P.; de Leeuw, Dago M.; Blom, Paul W. M.

    The stability of molecular junctions is crucial for any application of molecular electronics. Degradation of molecular junctions when exposed to ambient conditions is regularly observed. In this report the stability of large-area molecular junctions under ambient conditions for more than two years

  10. Dynamics of pi-junction interferometer circuits

    DEFF Research Database (Denmark)

    Kornkev, V.K.; Mozhaev, P.B.; Borisenko, I.V.

    2002-01-01

    The pi-junction superconducting circuit dynamics was studied by means of numerical simulation technique. Parallel arrays consisting of Josephson junctions of both 0- and pi-type were studied as a model of high-T-c grain-boundary Josephson junction. The array dynamics and the critical current depe...

  11. Au nanowire junction breakup through surface atom diffusion

    Science.gov (United States)

    Vigonski, Simon; Jansson, Ville; Vlassov, Sergei; Polyakov, Boris; Baibuz, Ekaterina; Oras, Sven; Aabloo, Alvo; Djurabekova, Flyura; Zadin, Vahur

    2018-01-01

    Metallic nanowires are known to break into shorter fragments due to the Rayleigh instability mechanism. This process is strongly accelerated at elevated temperatures and can completely hinder the functioning of nanowire-based devices like e.g. transparent conductive and flexible coatings. At the same time, arranged gold nanodots have important applications in electrochemical sensors. In this paper we perform a series of annealing experiments of gold and silver nanowires and nanowire junctions at fixed temperatures 473, 673, 873 and 973 K (200 °C, 400 °C, 600 °C and 700 °C) during a time period of 10 min. We show that nanowires are especially prone to fragmentation around junctions and crossing points even at comparatively low temperatures. The fragmentation process is highly temperature dependent and the junction region breaks up at a lower temperature than a single nanowire. We develop a gold parametrization for kinetic Monte Carlo simulations and demonstrate the surface diffusion origin of the nanowire junction fragmentation. We show that nanowire fragmentation starts at the junctions with high reliability and propose that aligning nanowires in a regular grid could be used as a technique for fabricating arrays of nanodots.

  12. Symmetry breaking in SNS junctions: edge transport and field asymmetries

    Science.gov (United States)

    Suominen, Henri; Nichele, Fabrizio; Kjaergaard, Morten; Rasmussen, Asbjorn; Danon, Jeroen; Flensberg, Karsten; Levitov, Leonid; Shabani, Javad; Palmstrom, Chris; Marcus, Charles

    We study magnetic diffraction patterns in a tunable superconductor-semiconductor-superconductor junction. By utilizing epitaxial growth of aluminum on InAs/InGaAs we obtain transparent junctions which display a conventional Fraunhofer pattern of the critical current as a function of applied perpendicular magnetic field, B⊥. By studying the angular dependence of the critical current with applied magnetic fields in the plane of the junction we find a striking anisotropy. We attribute this effect to dephasing of Andreev states in the bulk of the junction, leading to SQUID like behavior when the magnetic field is applied parallel to current flow. Furthermore, in the presence of both in-plane and perpendicular fields, asymmetries in +/-B⊥ are observed. We suggest possible origins and discuss the role of spin-orbit and Zeeman physics together with a background disorder potential breaking spatial symmetries of the junction. Research supported by Microsoft Project Q, the Danish National Research Foundation and the NSF through the National Nanotechnology Infrastructure Network.

  13. Human zonulin, a potential modulator of intestinal tight junctions.

    Science.gov (United States)

    Wang, W; Uzzau, S; Goldblum, S E; Fasano, A

    2000-12-01

    Intercellular tight junctions are dynamic structures involved in vectorial transport of water and electrolytes across the intestinal epithelium. Zonula occludens toxin derived from Vibrio cholerae interacts with a specific intestinal epithelial surface receptor, with subsequent activation of a complex intracellular cascade of events that regulate tight junction permeability. We postulated that this toxin may mimic the effect of a functionally and immunologically related endogenous modulator of intestinal tight junctions. Affinity-purified anti-zonula occludens toxin antibodies and the Ussing chamber assay were used to screen for one or more mammalian zonula occludens toxin analogues in both fetal and adult human intestine. A novel protein, zonulin, was identified that induces tight junction disassembly in non-human primate intestinal epithelia mounted in Ussing chambers. Comparison of amino acids in the active zonula occludens toxin fragment and zonulin permitted the identification of the putative receptor binding domain within the N-terminal region of the two proteins. Zonulin likely plays a pivotal role in tight junction regulation during developmental, physiological, and pathological processes, including tissue morphogenesis, movement of fluid, macromolecules and leukocytes between the intestinal lumen and the interstitium, and inflammatory/autoimmune disorders.

  14. Traumatic Tear of the Latissimus Dorsi Myotendinous Junction

    Science.gov (United States)

    Friedman, Michael V.; Stensby, J. Derek; Hillen, Travis J.; Demertzis, Jennifer L.; Keener, Jay D.

    2015-01-01

    A case of a latissimus dorsi myotendinous junction strain in an avid CrossFit athlete is presented. The patient developed acute onset right axillary burning and swelling and subsequent palpable pop with weakness while performing a “muscle up.” Magnetic resonance imaging examination demonstrated a high-grade tear of the right latissimus dorsi myotendinous junction approximately 9 cm proximal to its intact humeral insertion. There were no other injuries to the adjacent shoulder girdle structures. Isolated strain of the latissimus dorsi myotendinous junction is a very rare injury with a scarcity of information available regarding its imaging appearance and preferred treatment. This patient was treated conservatively and was able to resume active CrossFit training within 3 months. At 6 months postinjury, he had only a mild residual functional deficit compared with his preinjury level. PMID:26502450

  15. Tuning spin transport across two-dimensional organometallic junctions

    Science.gov (United States)

    Liu, Shuanglong; Wang, Yun-Peng; Li, Xiangguo; Fry, James N.; Cheng, Hai-Ping

    2018-01-01

    We study via first-principles modeling and simulation two-dimensional spintronic junctions made of metal-organic frameworks consisting of two Mn-phthalocyanine ferromagnetic metal leads and semiconducting Ni-phthalocyanine channels of various lengths. These systems exhibit a large tunneling magnetoresistance ratio; the transmission functions of such junctions can be tuned using gate voltage by three orders of magnitude. We find that the origin of this drastic change lies in the orbital alignment and hybridization between the leads and the center electronic states. With physical insight into the observed on-off phenomenon, we predict a gate-controlled spin current switch based on two-dimensional crystallines and offer general guidelines for designing spin junctions using 2D materials.

  16. Nanomanipulation and Lithography: The Building (and Modeling) of Carbon Nanotube Magnetic Tunnel Junctions

    Science.gov (United States)

    Louie, Richard Nam

    2002-12-01

    sizes, through the re-writing of a critical code segment that gives a hundredfold improvement in speed. Furthermore, the tight-binding model calculations are now generalized to include all types of nanotubes, not merely armchair tubes. On the experimental side, innovative junction fabrication procedures are investigated, including diamond-tip scanning probe lithography and e-beam lithography. Programs are written for the Nanometer Pattern Generation System to effect the creation of many junctions at once, to increase the chances of a CNT connecting two FM electrodes. As it is not prudent to rely solely on luck, the capability for tube nanomanipulation with an unprecedented level of control is also shown, and a procedure for controlled deposition upon chemically functionalized lithographic patterns is discussed. All of the techniques demonstrated can be used to create a magnetic tunnel junction to be refrigerated for extensive magnetoconductance studies.

  17. Accuracy and interobserver concordance of echocardiographic assessment of right ventricular size and systolic function: a quality control exercise.

    Science.gov (United States)

    Ling, Lee Fong; Obuchowski, Nancy A; Rodriguez, Leonardo; Popovic, Zoran; Kwon, Deborah; Marwick, Thomas H

    2012-07-01

    Accurate assessment of right ventricular (RV) size (RVS) and RV systolic function (RVSF) is vital in the management of various conditions, but their assessment is challenging using echocardiography. The aim of this study was to determine the accuracy and interobserver concordance of qualitative and quantitative RV echocardiography. Fifteen readers evaluated RV function in 12 patients (360 readings) who underwent echocardiography and cardiac magnetic resonance for RV assessment. Readers qualitatively estimated RVS and RVSF as normal, mild, moderate, or severe and then reassessed quantitatively by adding RV dimensions, fractional area change, S', tricuspid annular plane systolic excursion, and RV index of myocardial performance. Cardiac magnetic resonance was used as the reference standard for grading RVS and RVSF. Quantitative measurements increased accuracy and interreader agreement compared to qualitative assessment alone, especially in normal categories. Readers' accuracy for diagnosing normal and severe RVS increased from 38% to 78% (P = .001) and from 70% to 97% (P = .018), and readers' accuracy for diagnosing normal and mild RVSF increased from 52% to 84% (P value of 0.40 to 0.77 (fair to good agreement) for RVS and from 0.43 to 0.66 (moderate to good agreement) for RVSF. Visual estimation of RVS and RVSF is inaccurate and has wide interobserver variability. Quantitation improves accuracy and reliability, especially in distinction of normal and abnormal. The reliability of mild and moderate grades remains inadequate, and further guidance is needed for the classification of abnormal categories. Copyright © 2012 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.

  18. Genetic Ablation of Soluble TNF Does Not Affect Lesion Size and Functional Recovery after Moderate Spinal Cord Injury in Mice

    Directory of Open Access Journals (Sweden)

    Ditte Gry Ellman

    2016-01-01

    Full Text Available Traumatic spinal cord injury (SCI is followed by an instant increase in expression of the microglial-derived proinflammatory cytokine tumor necrosis factor (TNF within the lesioned cord. TNF exists both as membrane-anchored TNF (mTNF and as cleaved soluble TNF (solTNF. We previously demonstrated that epidural administration of a dominant-negative inhibitor of solTNF, XPro1595, to the contused spinal cord resulted in changes in Iba1 protein expression in microglia/macrophages, decreased lesion volume, and improved locomotor function. Here, we extend our studies using mice expressing mTNF, but no solTNF (mTNFΔ/Δ, to study the effect of genetic ablation of solTNF on SCI. We demonstrate that TNF levels were significantly decreased within the lesioned spinal cord 3 days after SCI in mTNFΔ/Δ mice compared to littermates. This decrease did, however, not translate into significant changes in other pro- and anti-inflammatory cytokines (IL-10, IL-1β, IL-6, IL-5, IL-2, CXCL1, CCL2, or CCL5, despite a tendency towards increased IL-10 and decreased IL-1β, TNFR1, and TNFR2 levels in mTNFΔ/Δ mice. In addition, microglial and leukocyte infiltration, activation state (Iba1, CD11b, CD11c, CD45, and MHCII, lesion size, and functional outcome after moderate SCI were comparable between genotypes. Collectively, our data demonstrate that genetic ablation of solTNF does not significantly modulate postlesion outcome after SCI.

  19. Electron Transport through Porphyrin Molecular Junctions

    Science.gov (United States)

    Zhou, Qi

    -molecule-metal junctions, and in applications related to integrating molecules as functional units in electronic devices. Future work related to this thesis may include the molecular conductance based on reduction-oxidation (redox) properties of iron ligated porphyrins for the application of molecular switches and molecular memory elements.

  20. An EMMPRIN–γ-catenin–Nm23 complex drives ATP production and actomyosin contractility at endothelial junctions

    Science.gov (United States)

    Moreno, Vanessa; Gonzalo, Pilar; Gómez-Escudero, Jesús; Pollán, Ángela; Acín-Pérez, Rebeca; Breckenridge, Mark; Yáñez-Mó, María; Barreiro, Olga; Orsenigo, Fabrizio; Kadomatsu, Kenji; Chen, Christopher S.; Enríquez, José A.; Dejana, Elisabetta; Sánchez-Madrid, Francisco; Arroyo, Alicia G.

    2014-01-01

    ABSTRACT Cell–cell adhesions are important sites through which cells experience and resist forces. In endothelial cells, these forces regulate junction dynamics and determine endothelial barrier strength. We identify the Ig superfamily member EMMPRIN (also known as basigin) as a coordinator of forces at endothelial junctions. EMMPRIN localization at junctions correlates with endothelial junction strength in different mouse vascular beds. Accordingly, EMMPRIN-deficient mice show altered junctions and increased junction permeability. Lack of EMMPRIN alters the localization and function of VE-cadherin (also known as cadherin-5) by decreasing both actomyosin contractility and tugging forces at endothelial cell junctions. EMMPRIN ensures proper actomyosin-driven maturation of competent endothelial junctions by forming a molecular complex with γ-catenin (also known as junction plakoglobin) and Nm23 (also known as NME1), a nucleoside diphosphate kinase, thereby locally providing ATP to fuel the actomyosin machinery. These results provide a novel mechanism for the regulation of actomyosin contractility at endothelial junctions and might have broader implications in biological contexts such as angiogenesis, collective migration and tissue morphogenesis by coupling compartmentalized energy production to junction assembly. PMID:24994937

  1. An EMMPRIN-γ-catenin-Nm23 complex drives ATP production and actomyosin contractility at endothelial junctions.

    Science.gov (United States)

    Moreno, Vanessa; Gonzalo, Pilar; Gómez-Escudero, Jesús; Pollán, Ángela; Acín-Pérez, Rebeca; Breckenridge, Mark; Yáñez-Mó, María; Barreiro, Olga; Orsenigo, Fabrizio; Kadomatsu, Kenji; Chen, Christopher S; Enríquez, José A; Dejana, Elisabetta; Sánchez-Madrid, Francisco; Arroyo, Alicia G

    2014-09-01

    Cell-cell adhesions are important sites through which cells experience and resist forces. In endothelial cells, these forces regulate junction dynamics and determine endothelial barrier strength. We identify the Ig superfamily member EMMPRIN (also known as basigin) as a coordinator of forces at endothelial junctions. EMMPRIN localization at junctions correlates with endothelial junction strength in different mouse vascular beds. Accordingly, EMMPRIN-deficient mice show altered junctions and increased junction permeability. Lack of EMMPRIN alters the localization and function of VE-cadherin (also known as cadherin-5) by decreasing both actomyosin contractility and tugging forces at endothelial cell junctions. EMMPRIN ensures proper actomyosin-driven maturation of competent endothelial junctions by forming a molecular complex with γ-catenin (also known as junction plakoglobin) and Nm23 (also known as NME1), a nucleoside diphosphate kinase, thereby locally providing ATP to fuel the actomyosin machinery. These results provide a novel mechanism for the regulation of actomyosin contractility at endothelial junctions and might have broader implications in biological contexts such as angiogenesis, collective migration and tissue morphogenesis by coupling compartmentalized energy production to junction assembly. © 2014. Published by The Company of Biologists Ltd.

  2. Electronic transport properties of phenylacetylene molecular junctions

    International Nuclear Information System (INIS)

    Liu Wen; Cheng Jie; Yan Cui-Xia; Li Hai-Hong; Wang Yong-Juan; Liu De-Sheng

    2011-01-01

    Electronic transport properties of a kind of phenylacetylene compound— (4-mercaptophenyl)-phenylacetylene are calculated by the first-principles method in the framework of density functional theory and the nonequilibrium Green's function formalism. The molecular junction shows an obvious rectifying behaviour at a bias voltage larger than 1.0 V. The rectification effect is attributed to the asymmetry of the interface contacts. Moreover, at a bias voltage larger than 2.0 V, which is not referred to in a relevant experiment [Fang L, Park J Y, Ma H, Jen A K Y and Salmeron M 2007 Langmuir 23 11522], we find a negative differential resistance phenomenon. The negative differential resistance effect may originate from the change of the delocalization degree of the molecular orbitals induced by the bias. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  3. Ferromagnetic Josephson Junctions for Cryogenic Memory

    Science.gov (United States)

    Niedzielski, Bethany M.; Gingrich, Eric C.; Khasawneh, Mazin A.; Loloee, Reza; Pratt, William P., Jr.; Birge, Norman O.

    2015-03-01

    Josephson junctions containing ferromagnetic materials are of interest for both scientific and technological purposes. In principle, either the amplitude of the critical current or superconducting phase shift across the junction can be controlled by the relative magnetization directions of the ferromagnetic layers in the junction. Our approach concentrates on phase control utilizing two junctions in a SQUID geometry. We will report on efforts to control the phase of junctions carrying either spin-singlet or spin-triplet supercurrent for cryogenic memory applications. Supported by Northorp Grumman Corporation and by IARPA under SPAWAR Contract N66001-12-C-2017.

  4. Adsorptive stripping voltammetric determination of nitroimidazole derivative on multiwalled carbon nanotube modified electrodes: influence of size and functionalization of nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Jara-Ulloa, Paola; Canete-Rosales, Paulina; Nunez-Vergara, Luis J; Squella, Juan A., E-mail: asquella@ciq.uchile.c [University of Chile, Santiago (Chile). Chemical and Pharmaceutical Sciences Faculty. Bioelectrochemistry Lab.

    2011-07-01

    1-Methyl-4-nitro-2-bromine methylimidazole (4-NimMeBr), was electrochemically reduced on mercury, glassy carbon and multiwalled carbon nanotubes (MWCNT) modified electrodes. 4-NimMeBr was adsorbed on the MWCNT modified electrode thus permitting the implementation of an adsorptive stripping voltammetric (ASV) method. We have used 4-NimMeBr as a prototype electroactive nitro compound to study the effect of both the size of the nanotubes and its functionalization by oxidation. The oxidized MWCNT forms better dispersions than the non-oxidized, producing electrode surface with higher density of MWCNT as was determined by electrochemical mapping using scanning electrochemical microscopy (SECM). Under the optimized conditions, the peak current was proportional to the concentration of 4-NimMeBr in the range of 10{sup -6} mol L{sup -1} to 10{sup -4} mol L{sup -1} with detection and quantification limits of 4.41 x 10{sup -6} mol L{sup -1} and 6.21 x 10{sup -6} mol L{sup -1}, respectively. The sensibility of bare electrode was 0.01 {mu}A per mmol L{sup -1}, which was lower than the value of 5.34 and 6.97 mA per mmol L{sup -1} obtained using short and large oxidized MWCNT, respectively. (author)

  5. Molecular series-tunneling junctions.

    Science.gov (United States)

    Liao, Kung-Ching; Hsu, Liang-Yan; Bowers, Carleen M; Rabitz, Herschel; Whitesides, George M

    2015-05-13

    Charge transport through junctions consisting of insulating molecular units is a quantum phenomenon that cannot be described adequately by classical circuit laws. This paper explores tunneling current densities in self-assembled monolayer (SAM)-based junctions with the structure Ag(TS)/O2C-R1-R2-H//Ga2O3/EGaIn, where Ag(TS) is template-stripped silver and EGaIn is the eutectic alloy of gallium and indium; R1 and R2 refer to two classes of insulating molecular units-(CH2)n and (C6H4)m-that are connected in series and have different tunneling decay constants in the Simmons equation. These junctions can be analyzed as a form of series-tunneling junctions based on the observation that permuting the order of R1 and R2 in the junction does not alter the overall rate of charge transport. By using the Ag/O2C interface, this system decouples the highest occupied molecular orbital (HOMO, which is localized on the carboxylate group) from strong interactions with the R1 and R2 units. The differences in rates of tunneling are thus determined by the electronic structure of the groups R1 and R2; these differences are not influenced by the order of R1 and R2 in the SAM. In an electrical potential model that rationalizes this observation, R1 and R2 contribute independently to the height of the barrier. This model explicitly assumes that contributions to rates of tunneling from the Ag(TS)/O2C and H//Ga2O3 interfaces are constant across the series examined. The current density of these series-tunneling junctions can be described by J(V) = J0(V) exp(-β1d1 - β2d2), where J(V) is the current density (A/cm(2)) at applied voltage V and βi and di are the parameters describing the attenuation of the tunneling current through a rectangular tunneling barrier, with width d and a height related to the attenuation factor β.

  6. Active zones of mammalian neuromuscular junctions: formation, density, and aging.

    Science.gov (United States)

    Nishimune, Hiroshi

    2012-12-01

    Presynaptic active zones are synaptic vesicle release sites that play essential roles in the function and pathology of mammalian neuromuscular junctions (NMJs). The molecular mechanisms of active zone organization use presynaptic voltage-dependent calcium channels (VDCCs) in NMJs as scaffolding proteins. VDCCs interact extracellularly with the muscle-derived synapse organizer, laminin β2 and interact intracellularly with active zone-specific proteins, such as Bassoon, CAST/Erc2/ELKS2alpha, ELKS, Piccolo, and RIMs. These molecular mechanisms are supported by studies in P/Q- and N-type VDCCs double-knockout mice, and they are consistent with the pathological conditions of Lambert-Eaton myasthenic syndrome and Pierson syndrome, which are caused by autoantibodies against VDCCs or by a laminin β2 mutation. During normal postnatal maturation, NMJs maintain the density of active zones, while NMJs triple their size. However, active zones become impaired during aging. Propitiously, muscle exercise ameliorates the active zone impairment in aged NMJs, which suggests the potential for therapeutic strategies. © 2012 New York Academy of Sciences.

  7. A perisynaptic ménage à trois between Dlg, DLin-7, and Metro controls proper organization of Drosophila synaptic junctions.

    Science.gov (United States)

    Bachmann, André; Kobler, Oliver; Kittel, Robert J; Wichmann, Carolin; Sierralta, Jimena; Sigrist, Stephan J; Gundelfinger, Eckart D; Knust, Elisabeth; Thomas, Ulrich

    2010-04-28

    Structural plasticity of synaptic junctions is a prerequisite to achieve and modulate connectivity within nervous systems, e.g., during learning and memory formation. It demands adequate backup systems that allow remodeling while retaining sufficient stability to prevent unwanted synaptic disintegration. The strength of submembranous scaffold complexes, which are fundamental to the architecture of synaptic junctions, likely constitutes a crucial determinant of synaptic stability. Postsynaptic density protein-95 (PSD-95)/ Discs-large (Dlg)-like membrane-associated guanylate kinases (DLG-MAGUKs) are principal scaffold proteins at both vertebrate and invertebrate synapses. At Drosophila larval glutamatergic neuromuscular junctions (NMJs) DlgA and DlgS97 exert pleiotropic functions, probably reflecting a few known and a number of yet-unknown binding partners. In this study we have identified Metro, a novel p55/MPP-like Drosophila MAGUK as a major binding partner of perisynaptic DlgS97 at larval NMJs. Based on homotypic LIN-2,-7 (L27) domain interactions, Metro stabilizes junctional DlgS97 in a complex with the highly conserved adaptor protein DLin-7. In a remarkably interdependent manner, Metro and DLin-7 act downstream of DlgS97 to control NMJ expansion and proper establishment of synaptic boutons. Using quantitative 3D-imaging we further demonstrate that the complex controls the size of postsynaptic glutamate receptor fields. Our findings accentuate the importance of perisynaptic scaffold complexes for synaptic stabilization and organization.

  8. Single Molecule Nanoelectrochemistry in Electrical Junctions.

    Science.gov (United States)

    Nichols, Richard J; Higgins, Simon J

    2016-11-15

    It is now possible to reliably measure single molecule conductance in a wide variety of environments including organic liquids, ultrahigh vacuum, water, ionic liquids, and electrolytes. The most commonly used methods deploy scanning probe microscopes, mechanically formed break junctions, or lithographically formed nanogap contacts. Molecules are generally captured between a pair of facing electrodes, and the junction current response is measured as a function of bias voltage. Gating electrodes can also be added so that the electrostatic potential at the molecular bridge can be independently controlled by this third noncontacting electrode. This can also be achieved in an electrolytic environment using a four-electrode bipotentiostatic configuration, which allows independent electrode potential control of the two contacting electrodes. This is commonly realized using an electrochemical STM and enables single molecule electrical characterization as a function of electrode potential and redox state of the molecular bridge. This has emerged as a powerful tool in modern interfacial electrochemistry and nanoelectrochemistry for studying charge transport across single molecules as a function of electrode potential and the electrolytic environments. Such measurements are possible in electrolytes ranging from aqueous buffers to nonaqueous ionic liquids. In this Account, we illustrate a number of examples of single molecule electrical measurements under electrode potential control use a scanning tunneling microscope (STM) and demonstrate how these can help in the understanding of charge transport in single molecule junctions. Examples showing charge transport following phase coherent tunneling to incoherent charge hopping across redox active molecular bridges are shown. In the case of bipyridinium (or viologen) molecular wires, it is shown how electrochemical reduction leads to an increase of the single molecule conductance, which is controlled by the liquid electrochemical

  9. Electrophysiological study in neuromuscular junction disorders

    Directory of Open Access Journals (Sweden)

    Ajith Cherian

    2013-01-01

    Full Text Available This review is on ultrastructure and subcellular physiology at normal and abnormal neuromuscular junctions. The clinical and electrophysiological findings in myasthenia gravis, Lambert-Eaton myasthenic syndrome (LEMS, congenital myasthenic syndromes, and botulinum intoxication are discussed. Single fiber electromyography (SFEMG helps to explain the basis of testing neuromuscular junction function by repetitive nerve stimulation (RNS. SFEMG requires skill and patience and its availability is limited to a few centers. For RNS supramaximal stimulation is essential and so is display of the whole waveform of each muscle response at maximum amplitude. The amplitudes of the negative phase of the first and fourth responses are measured from baseline to negative peak, and the percent change of the fourth response compared with the first represents the decrement or increment. A decrement greater than 10% is accepted as abnormal and smooth progression of response amplitude train and reproducibility form the crux. In suspected LEMS the effect of fast rates of stimulation should be determined after RNS response to slow rates of stimulation. Caution is required to avoid misinterpretation of potentiation and pseudofacilitation.

  10. Molecular Diffusion through Cyanobacterial Septal Junctions

    Directory of Open Access Journals (Sweden)

    Mercedes Nieves-Morión

    2017-01-01

    Full Text Available Heterocyst-forming cyanobacteria grow as filaments in which intercellular molecular exchange takes place. During the differentiation of N2-fixing heterocysts, regulators are transferred between cells. In the diazotrophic filament, vegetative cells that fix CO2 through oxygenic photosynthesis provide the heterocysts with reduced carbon and heterocysts provide the vegetative cells with fixed nitrogen. Intercellular molecular transfer has been traced with fluorescent markers, including calcein, 5-carboxyfluorescein, and the sucrose analogue esculin, which are observed to move down their concentration gradient. In this work, we used fluorescence recovery after photobleaching (FRAP assays in the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 to measure the temperature dependence of intercellular transfer of fluorescent markers. We find that the transfer rate constants are directly proportional to the absolute temperature. This indicates that the “septal junctions” (formerly known as “microplasmodesmata” linking the cells in the filament allow molecular exchange by simple diffusion, without any activated intermediate state. This constitutes a novel mechanism for molecular transfer across the bacterial cytoplasmic membrane, in addition to previously characterized mechanisms for active transport and facilitated diffusion. Cyanobacterial septal junctions are functionally analogous to the gap junctions of metazoans.

  11. Stress analysis of PCV nozzle junction

    International Nuclear Information System (INIS)

    Uchiyama, Shoichi; Oikawa, Tsuneo; Hoshino, Seizo

    1976-01-01

    Most of various pressure vessels comprise each one cylindrical shell and one or more nozzles. In this study, in order to analyze the stress in the structures of this type as minutely and exactly as possible, the program for stress analysis by the finite element method was made, which is required for the strength analysis for three-dimensional structures. Especially, the problem of the stress distribution around nozzle junctions was solved theoretically with the program. The program for the analysis developed in this study is provided with various functions, such as the input generator for cylindrical, conical and spherical shells, and plotter, and is very covenient. The accuracy of analysis is very good. The method of analysis and the calculation of the rigidity matrices for the deformation in plane and bending are explained. The result of the stress analysis around the nozzle junctions of a containment vessel with this program was in good agreement with experimental data and the result with SAP-4 code, therefore the propriety of the calculated result with this program was proved. Also calculations were carried out on three cases, namely a flat plate fixed at one end with distributed load, a cylinder fixed at one end with internal pressure, and an I-beam fixed at one end with concentrated load. The calculated results agreed well with theoretical solutions in all cases. (Kako, I.)

  12. An Evaluation of Test and Physical Uncertainty of Measuring Vibration in Wooden Junctions

    DEFF Research Database (Denmark)

    Dickow, Kristoffer Ahrens; Kirkegaard, Poul Henning; Andersen, Lars Vabbersgaard

    2012-01-01

    In the present paper a study of test and material uncertainty in modal analysis of certain wooden junctions is presented. The main structure considered here is a T-junction made from a particleboard plate connected to a spruce beam of rectangular cross section. The size of the plate is 1.2 m by 0.......6 m. The T-junctions represent cut-outs of actual full size floor assemblies. The aim of the experiments is to investigate the underlying uncertainties of both the test method as well as variation in material and craftmanship. For this purpose, ten nominally identical junctions are tested and compared...... to each other in terms of modal parameters such as natural frequencies, modeshapes and damping. Considerations regarding the measurement procedure and test setup are discussed. The results indicate a large variation of the response at modes where the coupling of torsion in the beam to bending of the plate...

  13. Self-positioned thin Pb-alloy base electrode Josephson junction

    International Nuclear Information System (INIS)

    Kuroda, K.; Sato, K.

    1986-01-01

    A self-positioned thin (SPOT) Pb-alloy base electrode Josephson junction is developed. In this junction, a 50-nm thick Pb-alloy base electrode is restricted within the junction region on an Nb underlayer using a self-alignment technique. The grain size reduction and the base electrode area restriction greatly improve thermal cycling stability, where the thermal cycling tests of 4000 proposed junctions (5 x 5 μm 2 ) showed no failures after 4000 cycles. In addition, the elimination of insulator layer stress on the Pb-alloy base electrode rectifies the problem of size effect on current density. The Nb underlayers also serve to isolate the Pb-alloy base electrodes from the resistors

  14. Size variability of the unit building block of peripheral light-harvesting antennas as a strategy for effective functioning of antennas of variable size that is controlled in vivo by light intensity.

    Science.gov (United States)

    Taisova, A S; Yakovlev, A G; Fetisova, Z G

    2014-03-01

    This work continuous a series of studies devoted to discovering principles of organization of natural antennas in photosynthetic microorganisms that generate in vivo large and highly effective light-harvesting structures. The largest antenna is observed in green photosynthesizing bacteria, which are able to grow over a wide range of light intensities and adapt to low intensities by increasing of size of peripheral BChl c/d/e antenna. However, increasing antenna size must inevitably cause structural changes needed to maintain high efficiency of its functioning. Our model calculations have demonstrated that aggregation of the light-harvesting antenna pigments represents one of the universal structural factors that optimize functioning of any antenna and manage antenna efficiency. If the degree of aggregation of antenna pigments is a variable parameter, then efficiency of the antenna increases with increasing size of a single aggregate of the antenna. This means that change in degree of pigment aggregation controlled by light-harvesting antenna size is biologically expedient. We showed in our previous work on the oligomeric chlorosomal BChl c superantenna of green bacteria of the Chloroflexaceae family that this principle of optimization of variable antenna structure, whose size is controlled by light intensity during growth of bacteria, is actually realized in vivo. Studies of this phenomenon are continued in the present work, expanding the number of studied biological materials and investigating optical linear and nonlinear spectra of chlorosomes having different structures. We show for oligomeric chlorosomal superantennas of green bacteria (from two different families, Chloroflexaceae and Oscillochloridaceae) that a single BChl c aggregate is of small size, and the degree of BChl c aggregation is a variable parameter, which is controlled by the size of the entire BChl c superantenna, and the latter, in turn, is controlled by light intensity in the course of cell

  15. Handedness- and Brain Size-Related Efficiency Differences in Small-World Brain Networks: A Resting-State Functional Magnetic Resonance Imaging Study

    OpenAIRE

    Li, Meiling; Wang, Junping; Liu, Feng; Chen, Heng; Lu, Fengmei; Wu, Guorong; Yu, Chunshui; Chen, Huafu

    2015-01-01

    The human brain has been described as a complex network, which integrates information with high efficiency. However, the relationships between the efficiency of human brain functional networks and handedness and brain size remain unclear. Twenty-one left-handed and 32 right-handed healthy subjects underwent a resting-state functional magnetic resonance imaging scan. The whole brain functional networks were constructed by thresholding Pearson correlation matrices of 90 cortical and subcortical...

  16. Schwann Cells in Neuromuscular Junction Formation and Maintenance.

    Science.gov (United States)

    Barik, Arnab; Li, Lei; Sathyamurthy, Anupama; Xiong, Wen-Cheng; Mei, Lin

    2016-09-21

    The neuromuscular junction (NMJ) is a tripartite synapse that is formed by motor nerve terminals, postjunctional muscle membranes, and terminal Schwann cells (TSCs) that cover the nerve-muscle contact. NMJ formation requires intimate communications among the three different components. Unlike nerve-muscle interaction, which has been well characterized, less is known about the role of SCs in NMJ formation and maintenance. We show that SCs in mice lead nerve terminals to prepatterned AChRs. Ablating SCs at E8.5 (i.e., prior nerve arrival at the clusters) had little effect on aneural AChR clusters at E13.5, suggesting that SCs may not be necessary for aneural clusters. SC ablation at E12.5, a time when phrenic nerves approach muscle fibers, resulted in smaller and fewer nerve-induced AChR clusters; however, SC ablation at E15.5 reduced AChR cluster size but had no effect on cluster density, suggesting that SCs are involved in AChR cluster maturation. Miniature endplate potential amplitude, but not frequency, was reduced when SCs were ablated at E15.5, suggesting that postsynaptic alterations may occur ahead of presynaptic deficits. Finally, ablation of SCs at P30, after NMJ maturation, led to NMJ fragmentation and neuromuscular transmission deficits. Miniature endplate potential amplitude was reduced 3 d after SC ablation, but both amplitude and frequency were reduced 6 d after. Together, these results indicate that SCs are not only required for NMJ formation, but also necessary for its maintenance; and postsynaptic function and structure appeared to be more sensitive to SC ablation. Neuromuscular junctions (NMJs) are critical for survival and daily functioning. Defects in NMJ formation during development or maintenance in adulthood result in debilitating neuromuscular disorders. The role of Schwann cells (SCs) in NMJ formation and maintenance was not well understood. We genetically ablated SCs during development and after NMJ formation to investigate the consequences

  17. Droplet formation in microfluidic T-junction generators operating in the transitional regime. III. Dynamic surfactant effects.

    Science.gov (United States)

    Glawdel, Tomasz; Ren, Carolyn L

    2012-08-01

    This study extends our previous work on droplet generation in microfluidic T-junction generators to include dynamic interfacial tension effects created by the presence of surfactants. In Paper I [T. Glawdel, C. Elbuken, and C. L. Ren, Phys. Rev. E 85, 016322 (2012)], we presented experimental findings regarding the formation process in the squeezing-to-transition regime, and in Paper II [T. Glawdel, C. Elbuken, and C. L. Ren, Phys. Rev. E 85, 016323 (2012)] we developed a theoretical model that describes the performance of T-junction generators without surfactants. Here we study dynamic interfacial tension effects for two surfactants, one with a small molecular weight that adsorbs quickly, and the other with a large molecular weight that adsorbs slowly. Using the force balance developed in Paper II we extract the dynamic interfacial tension from high speed videos obtained during experiments. We then develop a theoretical model to predict the dynamic interfacial tension in microfluidic T-junction generators as a function of the surfactant properties, flow conditions, and generator design. This model is then incorporated into the overall model for generator performance to effectively predict the size of droplets produced when surfactants are present.

  18. Josephson junctions and circle maps

    Energy Technology Data Exchange (ETDEWEB)

    Bak, P; Bohr, T; Jensen, M H; Christiansen, P V

    1984-01-01

    The return map of a differential equation for the current driven Josephson junction, or the damped driven pendulum, is shown numerically to be a circle map. Phase locking, noise and hysteresis, can thus be understood in a simple and coherent way. The transition to chaos is related to the development of a cubic inflection point. Recent theoretical results on universal behavior at the transition to chaos can readily be checked experimentally by studying I-V characteristics. 17 references, 1 figure.

  19. Observation of molecular level behavior in molecular electronic junction device

    Science.gov (United States)

    Maitani, Masato

    In this dissertation, I utilize AFM based scanning probe measurement and surface enhanced Raman scattering based vibrational spectroscopic analysis to directly characterize topographic, electronic, and chemical properties of molecules confined in the local area of M3 junction to elucidate the molecular level behavior of molecular junction electronic devices. In the introduction, the characterization of molecular electronic devices with different types of metal-molecule-metal (M3) structures based upon self-assembled monolayers (SAMs) is reviewed. A background of the characterization methods I use in this dissertation, conducting probe atomic force microscopy (cp-AFM) and surface enhanced Raman spectroscopy (SERS), is provided in chapter 1. Several attempts are performed to create the ideal top metal contacts on SAMs by metal vapor phase deposition in order to prevent the metal penetration inducing critical defects of the molecular electronic devices. The scanning probe microscopy (SPM), such as cp-AFM, contact mode (c-) AFM and non-contact mode (nc-) AFM, in ultra high vacuum conditions are utilized to study the process of the metal-SAM interface construction in terms of the correlation between the morphological and electrical properties including the metal nucleation and filament generation as a function of the functionalization of long-chain alkane thiolate SAMs on Au. In chapter 2, the nascent condensation process of vapor phase Al deposition on inert and reactive SAMs are studied by SPM. The results of top deposition, penetration, and filament generation of deposited Al are discussed and compared to the results previously observed by spectroscopic measurements. Cp-AFM was shown to provide new insights into Al filament formation which has not been observed by conventional spectroscopic analysis. Additionally, the electronic characteristics of individual Al filaments are measured. Chapter 3 reveals SPM characterization of Au deposition onto --COOH terminated SAMs

  20. Squeezed States in Josephson Junctions.

    Science.gov (United States)

    Hu, X.; Nori, F.

    1996-03-01

    We have studied quantum fluctuation properties of Josephson junctions in the limit of large Josephson coupling energy and small charging energy, when the eigenstates of the system can be treated as being nearly localized. We have considered(X. Hu and F. Nori, preprints.) a Josephson junction in a variety of situations, e.g., coupled to one or several of the following elements: a capacitor, an inductor (in a superconducting ring), and an applied current source. By solving an effective Shrödinger equation, we have obtained squeezed vacuum (coherent) states as the ground states of a ``free-oscillating'' (linearly-driven) Josephson junction, and calculated the uncertainties of its canonical momentum, charge, and coordinate, phase. We have also shown that the excited states of the various systems we consider are similar to the number states of a simple harmonic oscillator but with different fluctuation properties. Furthermore, we have obtained the time-evolution operators for these systems. These operators can make it easier to calculate the time-dependence of the expectation values and fluctuations of various quantities starting from an arbitrary initial state.

  1. Superconducting tunnel-junction refrigerator

    International Nuclear Information System (INIS)

    Melton, R.G.; Paterson, J.L.; Kaplan, S.B.

    1980-01-01

    The dc current through an S 1 -S 2 tunnel junction, with Δ 2 greater than Δ 1 , when biased with eV 1 +Δ 2 , will lower the energy in S 1 . This energy reduction will be shared by the phonons and electrons. This device is shown to be analogous to a thermoelectric refrigerator with an effective Peltier coefficient π* approx. Δ 1 /e. Tunneling calculations yield the cooling power P/sub c/, the electrical power P/sub e/ supplied by the bias supply, and the cooling efficiency eta=P/sub c//P/sub e/. The maximum cooling power is obtained for eV= +- (Δ 2 -Δ 1 ) and t 1 =T 1 /T/sub c/1 approx. 0.9. Estimates are made of the temperature difference T 2 -T 1 achievable in Al-Pb and Sn-Pb junctions with an Al 2 O 3 tunneling barrier. The performance of this device is shown to yield a maximum cooling efficiency eta approx. = Δ 1 /(Δ 2 -Δ 1 ) which can be compared with that available in an ideal Carnot refrigerator of eta=T 1 /(T 2 -T 1 ). The development of a useful tunnel-junction refrigerator requires a tunneling barrier with an effective thermal conductance per unit area several orders of magnitude less than that provided by the A1 2 O 3 barrier in the Al-Pb and Sn-Pb systems

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

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  3. Roles of gap junctions, connexins and pannexins in epilepsy

    Directory of Open Access Journals (Sweden)

    Shanthini eMylvaganam

    2014-05-01

    Full Text Available Enhanced gap junctional communication (GJC between neurons is considered a major factor underlying the neuronal synchrony driving seizure activity. In addition, the hippocampal sharp wave ripple complexes, associated with learning and seizures, are diminished by GJC blocking agents. Although gap junctional blocking drugs inhibit experimental seizures, they all have other nonspecific actions. Besides interneuronal GJC between dendrites, inter-axonal and inter-glial GJC is also considered important for seizure generation. Interestingly, in most studies of cerebral tissue from animal seizure models and from human patients with epilepsy, there is up-regulation of glial, but not neuronal gap junctional mRNA and protein. Significant changes in the expression and post-translational modification of the astrocytic connexin Cx43, and Panx1 were observed in an in vitro Co++ seizure model, further supporting a role for glia in seizure-genesis, although the reasons for this remain unclear. Further suggesting an involvement of astrocytic GJC in epilepsy, is the fact that the expression of astrocytic Cx mRNAs (Cxs 30 and 43 is several fold higher than that of neuronal Cx mRNAs (Cxs 36 and 45, and the number of glial cells outnumber neuronal cells in mammalian hippocampal and cortical tissue. Pannexin expression is also increased in both animal and human epileptic tissues. Specific Cx43 mimetic peptides, Gap 27 and SLS, inhibit the docking of astrocytic connexin Cx43 proteins from forming intercellular gap junctions, diminishing spontaneous seizures. Besides GJs, Cx membrane hemichannels in glia and Panx membrane channels in neurons and glia are also inhibited by gap junctional pharmacological blockers. Although there is no doubt that connexin-based gap junctions and hemichannels, and pannexin-based membrane channels are related to epilepsy, the specific details of how they are involved and how we can modulate their function for therapeutic purposes remain to

  4. Hyperglycaemia and diabetes impair gap junctional communication among astrocytes.

    Science.gov (United States)

    Gandhi, Gautam K; Ball, Kelly K; Cruz, Nancy F; Dienel, Gerald A

    2010-03-15

    Sensory and cognitive impairments have been documented in diabetic humans and animals, but the pathophysiology of diabetes in the central nervous system is poorly understood. Because a high glucose level disrupts gap junctional communication in various cell types and astrocytes are extensively coupled by gap junctions to form large syncytia, the influence of experimental diabetes on gap junction channel-mediated dye transfer was assessed in astrocytes in tissue culture and in brain slices from diabetic rats. Astrocytes grown in 15-25 mmol/l glucose had a slow-onset, poorly reversible decrement in gap junctional communication compared with those grown in 5.5 mmol/l glucose. Astrocytes in brain slices from adult STZ (streptozotocin)-treated rats at 20-24 weeks after the onset of diabetes also exhibited reduced dye transfer. In cultured astrocytes grown in high glucose, increased oxidative stress preceded the decrement in dye transfer by several days, and gap junctional impairment was prevented, but not rescued, after its manifestation by compounds that can block or reduce oxidative stress. In sharp contrast with these findings, chaperone molecules known to facilitate protein folding could prevent and rescue gap junctional impairment, even in the presence of elevated glucose level and oxidative stress. Immunostaining of Cx (connexin) 43 and 30, but not Cx26, was altered by growth in high glucose. Disruption of astrocytic trafficking of metabolites and signalling molecules may alter interactions among astrocytes, neurons and endothelial cells and contribute to changes in brain function in diabetes. Involvement of the microvasculature may contribute to diabetic complications in the brain, the cardiovascular system and other organs.

  5. Effect of peroral endoscopic myotomy on esophagogastric junction physiology in patients with achalasia

    NARCIS (Netherlands)

    Verlaan, Tessa; Rohof, Wout O.; Bredenoord, Albert J.; Eberl, Susanne; Rösch, Thomas; Fockens, Paul

    2013-01-01

    Pneumatic dilation and laparoscopic Heller myotomy improve parameters of esophageal function such as lower esophageal sphincter (LES) pressure, esophageal emptying, and esophagogastric junction (EGJ) distensibility. To evaluate the effect of peroral endoscopic myotomy (POEM) on esophagogastric

  6. Trade-offs between seed and leaf size (seed-phytomer-leaf theory): functional glue linking regenerative with life history strategies … and taxonomy with ecology?

    Science.gov (United States)

    Hodgson, John G; Santini, Bianca A; Montserrat Marti, Gabriel; Royo Pla, Ferran; Jones, Glynis; Bogaard, Amy; Charles, Mike; Font, Xavier; Ater, Mohammed; Taleb, Abdelkader; Poschlod, Peter; Hmimsa, Younes; Palmer, Carol; Wilson, Peter J; Band, Stuart R; Styring, Amy; Diffey, Charlotte; Green, Laura; Nitsch, Erika; Stroud, Elizabeth; Romo-Díez, Angel; de Torres Espuny, Lluis; Warham, Gemma

    2017-11-10

    While the 'worldwide leaf economics spectrum' (Wright IJ, Reich PB, Westoby M, et al. 2004. The worldwide leaf economics spectrum. Nature : 821-827) defines mineral nutrient relationships in plants, no unifying functional consensus links size attributes. Here, the focus is upon leaf size, a much-studied plant trait that scales positively with habitat quality and components of plant size. The objective is to show that this wide range of relationships is explicable in terms of a seed-phytomer-leaf (SPL) theoretical model defining leaf size in terms of trade-offs involving the size, growth rate and number of the building blocks (phytomers) of which the young shoot is constructed. Functional data for 2400+ species and English and Spanish vegetation surveys were used to explore interrelationships between leaf area, leaf width, canopy height, seed mass and leaf dry matter content (LDMC). Leaf area was a consistent function of canopy height, LDMC and seed mass. Additionally, size traits are partially uncoupled. First, broad laminas help confer competitive exclusion while morphologically large leaves can, through dissection, be functionally small. Secondly, leaf size scales positively with plant size but many of the largest-leaved species are of medium height with basally supported leaves. Thirdly, photosynthetic stems may represent a functionally viable alternative to 'small seeds + large leaves' in disturbed, fertile habitats and 'large seeds + small leaves' in infertile ones. Although key elements defining the juvenile growth phase remain unmeasured, our results broadly support SPL theory in that phytometer and leaf size are a product of the size of the initial shoot meristem (≅ seed mass) and the duration and quality of juvenile growth. These allometrically constrained traits combine to confer ecological specialization on individual species. Equally, they appear conservatively expressed within major taxa. Thus, 'evolutionary canalization' sensu Stebbins (Stebbins GL

  7. Effect of ventricular size and function on exercise performance and the electrocardiogram in repaired tetralogy of Fallot with pure pulmonary regurgitation

    International Nuclear Information System (INIS)

    Menon, Shaji C; Kaza, Aditya K; Puchalski, Michael D

    2012-01-01

    In repaired tetralogy of Fallot (TOF), exercise test parameters like peak oxygen uptake and ventilatory efficiency predict mortality. Studies have also suggested cardiac magnetic resonance (CMR)-derived right ventricular (RV) size threshold values for pulmonary valve replacement in repaired TOF. However, effects of proposed RV size on exercise capacity and morbidity are not known. The relationship between CMR-derived ventricular size, function, and pulmonary regurgitation (PR) and NYHA class, exercise performance, and electrocardiogram (ECG) was studied in patients of repaired TOF with pure PR in a retrospective review of records. 46 patients (22 females), mean age 14 years (8–30.8), were studied. There was no relationship between CMR-derived ventricular size, function, or PR and exercise test parameters, or NYHA class. RV end systolic and end diastolic volume correlated positively with the degree of PR. QRS duration on ECG correlated positively with RV end-diastolic volume (P < 0.01, r 2 = 0.34) and PR (P < 0.01, r 2 = 0.52). In repaired TOF and pure PR, there is no correlation between ventricular size or function and exercise performance. RV size increases with increasing PR. Timing of pulmonary valve replacement in TOF with pure PR needs further prospective evaluation for its effect on morbidity and mortality

  8. Observation of gap inhomogeneity in superconducting aluminum tunnel junctions

    International Nuclear Information System (INIS)

    Gilmartin, H.R.

    1982-01-01

    Experiments using a novel technique to investigate spatial variations in the superconducting gap parameter of aluminum films driven out of equilibrium by intense tunnel injection are described. The technique features fine spatial and energy resolution of the gap parameter. The experiments employed a finely focused laser spot scanned across the surface of a double tunnel junction sandwich to produce a very weak electrical signal that was analyzed to determine the gap parameter as a function of position in the plane of the device. Technical aspects of the problem are emphasized, since a new technique is presented. An elaborate explanation of the origin and analysis of the laser induced signal is given, as well as a detailed description of the experimental apparatus. Very briefly, the principle of operation is that a large flux of quasiparticles is injected through the lower junction of the sandwich into the middle aluminum film, and the upper junction serves to detect the effects of that injection. The middle film takes on two or more values of the gap parameter under injection, presumably indicating spatial variation. The presence of a small laser spot on a given point on the device perturbs the potential on the detector junction very slightly. That perturbation is measured as a function of bias current to determine the gap parameter of the middle film at that point. The spot is scanned in a raster pattern to produce a picture of the space dependence of the gap parameter

  9. Tuning the thermal conductance of molecular junctions with interference effects

    Science.gov (United States)

    Klöckner, J. C.; Cuevas, J. C.; Pauly, F.

    2017-12-01

    We present an ab initio study of the role of interference effects in the thermal conductance of single-molecule junctions. To be precise, using a first-principles transport method based on density functional theory, we analyze the coherent phonon transport in single-molecule junctions made of several benzene and oligo(phenylene ethynylene) derivatives. We show that the thermal conductance of these junctions can be tuned via the inclusion of substituents, which induces destructive interference effects and results in a decrease of the thermal conductance with respect to the unmodified molecules. In particular, we demonstrate that these interference effects manifest as antiresonances in the phonon transmission, whose energy positions can be tuned by varying the mass of the substituents. Our work provides clear strategies for the heat management in molecular junctions and, more generally, in nanostructured metal-organic hybrid systems, which are important to determine how these systems can function as efficient energy-conversion devices such as thermoelectric generators and refrigerators.

  10. Particle-size distribution and phosphorus forms as a function of hydrological forcing in the Yellow River.

    Science.gov (United States)

    Yao, Qing-Zhen; Du, Jun-Tao; Chen, Hong-Tao; Yu, Zhi-Gang

    2016-02-01

    Samples were collected monthly from January to December in 2010, and daily observations were made during the water-sediment regulation event in June-July 2010. Sequential extractions were applied to determine the forms of P in different particle-size fractions and to assess the potential bioavailability of particulate phosphorus (PP). The results indicated that exchangeable phosphorus, organic phosphorus, authigenic phosphorus, and refractory phosphorus increased with the decreasing of particulate size; conversely, detrital phosphorus decreased with the decreasing of particulate size. The content of bioavailable particulate phosphorus (BAPP) varied greatly in different sizes of particles. In general, the smaller the particle size, the higher the content of bioavailable phosphorus and its proportion in total phosphorous was found in these particles. Hydrological forcing controlled the variability in the major P phases found in the suspended sediments via changes in the sources and the particle grain-size distribution. The variation of particle sizes can be attributed also to different total suspended sediment (TSS) sources. Water-sediment regulation (WSR) mobilized only particulate matter from the riverbed, while during the rainstorm soil erosion and runoff were the main source. The BAPP fluxes associated with the "truly suspended" fraction was approximately 200 times larger than the dissolved inorganic phosphorus (DIP) flux. Thus, the transfer of fine particles to the open sea is most probably accompanied by BAPP release to the DIP and can support greater primary and secondary production.

  11. The Dissolution of Double Holliday Junctions

    DEFF Research Database (Denmark)

    Bizard, Anna H; Hickson, Ian D

    2014-01-01

    as "double Holliday junction dissolution." This reaction requires the cooperative action of a so-called "dissolvasome" comprising a Holliday junction branch migration enzyme (Sgs1/BLM RecQ helicase) and a type IA topoisomerase (Top3/TopoIIIα) in complex with its OB (oligonucleotide/oligosaccharide binding......Double Holliday junctions (dHJS) are important intermediates of homologous recombination. The separate junctions can each be cleaved by DNA structure-selective endonucleases known as Holliday junction resolvases. Alternatively, double Holliday junctions can be processed by a reaction known......) fold containing accessory factor (Rmi1). This review details our current knowledge of the dissolution process and the players involved in catalyzing this mechanistically complex means of completing homologous recombination reactions....

  12. Motion Interplay as a Function of Patient Parameters and Spot Size in Spot Scanning Proton Therapy for Lung Cancer

    Science.gov (United States)

    Grassberger, Clemens; Dowdell, Stephen; Lomax, Antony; Sharp, Greg; Shackleford, James; Choi, Noah; Willers, Henning; Paganetti, Harald

    2013-01-01

    Purpose Quantify the impact of respiratory motion on the treatment of lung tumors with spot scanning proton therapy. Methods and Materials 4D Monte Carlo simulations were used to assess the interplay effect, which results from relative motion of the tumor and the proton beam, on the dose distribution in the patient. Ten patients with varying tumor sizes (2.6-82.3cc) and motion amplitudes (3-30mm) were included in the study. We investigated the impact of the spot size, which varies between proton facilities, and studied single fractions and conventionally fractionated treatments. The following metrics were used in the analysis: minimum/maximum/mean dose, target dose homogeneity and 2-year local control rate (2y-LC). Results Respiratory motion reduces the target dose homogeneity, with the largest effects observed for the highest motion amplitudes. Smaller spot sizes (σ≈3mm) are inherently more sensitive to motion, decreasing target dose homogeneity on average by a factor ~2.8 compared to a larger spot size (σ≈13mm). Using a smaller spot size to treat a tumor with 30mm motion amplitude reduces the minimum dose to 44.7% of the prescribed dose, decreasing modeled 2y-LC from 87.0% to 2.7%, assuming a single fraction. Conventional fractionation partly mitigates this reduction, yielding a 2y-LC of 71.6%. For the large spot size, conventional fractionation increases target dose homogeneity and prevents a deterioration of 2y-LC for all patients. No correlation with tumor volume is observed. The effect on the normal lung dose distribution is minimal: observed changes in mean lung dose and lung V20 are interplay using a large spot size and conventional fractionation. For treatments employing smaller spot sizes and/or in the delivery of single fractions, interplay effects can lead to significant deterioration of the dose distribution and lower 2y-LC. PMID:23462423

  13. Radiation inactivation analysis of assimilatory NADH:nitrate reductase. Apparent functional sizes of partial activities associated with intact and proteolytically modified enzyme

    International Nuclear Information System (INIS)

    Solomonson, L.P.; McCreery, M.J.; Kay, C.J.; Barber, M.J.

    1987-01-01

    Recently we demonstrated that target sizes for the partial activities of nitrate reductase were considerably smaller than the 100-kDa subunit which corresponded to the target size of the full (physiologic) activity NADH:nitrate reductase. These results suggested that the partial activities resided on functionally independent domains and that radiation inactivation may be due to localized rather than extensive damage to protein structure. The present study extends these observations and addresses several associated questions. Monophasic plots were observed over a wide range of radiation doses, suggesting a single activity component in each case. No apparent differences were observed over a 10-fold range of concentration for each substrate, suggesting that the observed slopes were not due to marked changes in Km values. Apparent target sizes estimated for partial activities associated with native enzyme and with limited proteolysis products of native enzyme suggested that the functional size obtained by radiation inactivation analysis is independent of the size of the polypeptide chain. The presence of free radical scavengers during irradiation reduced the apparent target size of both the physiologic and partial activities by an amount ranging from 24 to 43%, suggesting that a free radical mechanism is at least partially responsible for the inactivation. Immunoblot analysis of nitrate reductase irradiated in the presence of free radical scavengers revealed formation of distinct bands at 90, 75, and 40 kDa with increasing doses of irradiation rather than complete destruction of the polypeptide chain

  14. Schedule-induced drinking as functions of interpellet interval and draught size in the Java macaque1

    Science.gov (United States)

    Allen, Joseph D.; Kenshalo, Dan R.

    1978-01-01

    Three Java monkeys received food pellets that were assigned by both ascending and descending series of fixed-time schedules whose values varied between 8 and 256 seconds. The draught size dispensed by a concurrently available water-delivery tube was systematically varied between 1.0 and 0.3 milliliter per lick at various fixed-time values during the second and third series determinations. Session water intake was bitonically related to the interpellet interval and was determined by the interaction of (1) the probability of initiating a drinking bout, which fell off at the highest interpellet intervals and, (2) the size of the bout, which increased directly with increases in interpellet interval. Variations in draught size had little effect on total session intakes, but reduced bout size at draught sizes of 0.5 milliliter and below. Thus, a volume-regulation process of schedule-induced drinking operated generally at the session-intake level, but was limited to higher draught sizes at the bout level. PMID:16812093

  15. Geodynamical simulation of the RRF triple junction

    Science.gov (United States)

    Wang, Z.; Wei, D.; Liu, M.; Shi, Y.; Wang, S.

    2017-12-01

    Triple junction is the point at which three plate boundaries meet. Three plates at the triple junction form a complex geological tectonics, which is a natural laboratory to study the interactions of plates. This work studies a special triple junction, the oceanic transform fault intersects the collinear ridges with different-spreading rates, which is free of influence of ridge-transform faults and nearby hotspots. First, we build 3-D numerical model of this triple junction used to calculate the stead-state velocity and temperature fields resulting from advective and conductive heat transfer. We discuss in detail the influence of the velocity and temperature fields of the triple junction from viscosity, spreading rate of the ridge. The two sides of the oceanic transform fault are different sensitivities to the two factors. And, the influence of the velocity mainly occurs within 200km of the triple junction. Then, we modify the model by adding a ridge-transform fault to above model and directly use the velocity structure of the Macquarie triple junction. The simulation results show that the temperature at both sides of the oceanic transform fault decreases gradually from the triple junction, but the temperature difference between the two sides is a constant about 200°. And, there is little effect of upwelling velocity away from the triple junction 100km. The model results are compared with observational data. The heat flux and thermal topography along the oceanic transform fault of this model are consistent with the observed data of the Macquarie triple junction. The earthquakes are strike slip distributed along the oceanic transform fault. Their depths are also consistent with the zone of maximum shear stress. This work can help us to understand the interactions of plates of triple junctions and help us with the foundation for the future study of triple junctions.

  16. Hysteresis development in superconducting Josephson junctions

    International Nuclear Information System (INIS)

    Refai, T.F.; Shehata, L.N.

    1988-09-01

    The resistively and capacitive shunted junction model is used to investigate hysteresis development in superconducting Josephson junctions. Two empirical formulas that relate the hysteresis width and the quasi-particle diffusion length in terms of the junctions electrical parameters, temperature and frequency are obtained. The obtained formulas provide a simple tool to investigate the full potentials of the hysteresis phenomena. (author). 9 refs, 3 figs

  17. Josephson tunnel junction microwave attenuator

    DEFF Research Database (Denmark)

    Koshelets, V. P.; Shitov, S. V.; Shchukin, A. V.

    1993-01-01

    A new element for superconducting electronic circuitry-a variable attenuator-has been proposed, designed, and successfully tested. The principle of operation is based on the change in the microwave impedance of a superconductor-insulator-superconductor (SIS) Josephson tunnel junction when dc biased...... at different points in the current-voltage characteristic. Both numerical calculations based on the Tien-Gordon theory and 70-GHz microwave experiments have confirmed the wide dynamic range (more than 15-dB attenuation for one stage) and the low insertion loss in the ''open'' state. The performance of a fully...

  18. Loss models for long Josephson junctions

    DEFF Research Database (Denmark)

    Olsen, O. H.; Samuelsen, Mogens Rugholm

    1984-01-01

    A general model for loss mechanisms in long Josephson junctions is presented. An expression for the zero-field step is found for a junction of overlap type by means of a perturbation method. Comparison between analytic solution and perturbation result shows good agreement.......A general model for loss mechanisms in long Josephson junctions is presented. An expression for the zero-field step is found for a junction of overlap type by means of a perturbation method. Comparison between analytic solution and perturbation result shows good agreement....

  19. Harmonic synchronization in resistively coupled Josephson junctions

    International Nuclear Information System (INIS)

    Blackburn, J.A.; Gronbech-Jensen, N.; Smith, H.J.T.

    1994-01-01

    The oscillations of two resistively coupled Josephson junctions biased only by a single dc current source are shown to lock harmonically in a 1:2 mode over a significant range of bias current, even when the junctions are identical. The dependence of this locking on both junction and coupling parameters is examined, and it is found that, for this particular two-junction configuration, 1:1 locking can never occur, and also that a minimum coupling coefficient is needed to support harmonic locking. Some issues related to subharmonic locking are also discussed

  20. Superconducting flux qubits with π-junctions

    International Nuclear Information System (INIS)

    Shcherbakova, Anastasia

    2014-01-01

    In this thesis, we present a fabrication technology of Al/AlO x /Al Josephson junctions on Nb pads. The described technology gives the possibility of combining a variety of Nb-based superconducting circuits, like pi-junction phase-shifters with sub-micron Al/AlO x /Al junctions. Using this approach, we fabricated hybrid Nb/Al flux qubits with and without the SFS-junctions and studied dispersive magnetic field response of these qubits as well as their spectroscopy characteristics.

  1. Finite-time and finite-size scalings in the evaluation of large-deviation functions: Numerical approach in continuous time.

    Science.gov (United States)

    Guevara Hidalgo, Esteban; Nemoto, Takahiro; Lecomte, Vivien

    2017-06-01

    Rare trajectories of stochastic systems are important to understand because of their potential impact. However, their properties are by definition difficult to sample directly. Population dynamics provides a numerical tool allowing their study, by means of simulating a large number of copies of the system, which are subjected to selection rules that favor the rare trajectories of interest. Such algorithms are plagued by finite simulation time and finite population size, effects that can render their use delicate. In this paper, we present a numerical approach which uses the finite-time and finite-size scalings of estimators of the large deviation functions associated to the distribution of rare trajectories. The method we propose allows one to extract the infinite-time and infinite-size limit of these estimators, which-as shown on the contact process-provides a significant improvement of the large deviation function estimators compared to the standard one.

  2. Finite-time and finite-size scalings in the evaluation of large-deviation functions: Numerical approach in continuous time

    Science.gov (United States)

    Guevara Hidalgo, Esteban; Nemoto, Takahiro; Lecomte, Vivien

    2017-06-01

    Rare trajectories of stochastic systems are important to understand because of their potential impact. However, their properties are by definition difficult to sample directly. Population dynamics provides a numerical tool allowing their study, by means of simulating a large number of copies of the system, which are subjected to selection rules that favor the rare trajectories of interest. Such algorithms are plagued by finite simulation time and finite population size, effects that can render their use delicate. In this paper, we present a numerical approach which uses the finite-time and finite-size scalings of estimators of the large deviation functions associated to the distribution of rare trajectories. The method we propose allows one to extract the infinite-time and infinite-size limit of these estimators, which—as shown on the contact process—provides a significant improvement of the large deviation function estimators compared to the standard one.

  3. Mitral regurgitation in myocardial infarction complicated by heart failure, left ventricular dysfunction, or both: prognostic significance and relation to ventricular size and function

    DEFF Research Database (Denmark)

    Amigoni, Maria; Meris, Alessandra; Thune, Jens Jakob

    2007-01-01

    AIMS: Mitral regurgitation (MR) confers independent risk in patients with acute myocardial infarction. We utilized data from the VALsartan In Acute myocardial iNfarcTion echo study to relate baseline MR to left ventricular (LV) size, shape, and function, and to assess the relationship between...

  4. Linking hydraulic traits to tropical forest function in a size-structured and trait-driven model (TFS v.1-Hydro)

    NARCIS (Netherlands)

    Christoffersen, Bradley O.; Gloor, Manuel; Fauset, Sophie; Fyllas, Nikolaos M.; Galbraith, David R.; Baker, Timothy R.; Kruijt, Bart; Rowland, Lucy; Fisher, Rosie A.; Binks, Oliver J.; Sevanto, Sanna; Xu, Chonggang; Jansen, Steven; Choat, Brendan; Mencuccini, Maurizio; McDowell, Nate G.; Meir, Patrick

    2016-01-01

    Forest ecosystem models based on heuristic water stress functions poorly predict tropical forest response to drought partly because they do not capture the diversity of hydraulic traits (including variation in tree size) observed in tropical forests. We developed a continuous porous media

  5. Towards a Guideline for Design of a Corporate Entrepreneurship Function for Business Development in Medium-Sized Technology-Based Companies

    NARCIS (Netherlands)

    Uittenbogaard, Boaz; Broens, Lute; Groen, Arend J.

    2005-01-01

    The speed with which global high-technology markets evolve makes companies recognize that an effective innovation process is the best way to guarantee competitiveness. However, when (medium-sized) companies then wish to set up a corporate entrepreneurship function to enhance business development

  6. Characterization of the Tetraspan Junctional Complex (4JC) superfamily.

    Science.gov (United States)

    Chou, Amy; Lee, Andre; Hendargo, Kevin J; Reddy, Vamsee S; Shlykov, Maksim A; Kuppusamykrishnan, Harikrishnan; Medrano-Soto, Arturo; Saier, Milton H

    2017-03-01

    Connexins or innexins form gap junctions, while claudins and occludins form tight junctions. In this study, statistical data, derived using novel software, indicate that these four junctional protein families and eleven other families of channel and channel auxiliary proteins are related by common descent and comprise the Tetraspan (4 TMS) Junctional Complex (4JC) Superfamily. These proteins all share similar 4 transmembrane α-helical (TMS) topologies. Evidence is presented that they arose via an intragenic duplication event, whereby a 2 TMS-encoding genetic element duplicated tandemly to give 4 TMS proteins. In cases where high resolution structural data were available, the conclusion of homology was supported by conducting structural comparisons. Phylogenetic trees reveal the probable relationships of these 15 families to each other. Long homologues containing fusions to other recognizable domains as well as internally duplicated or fused domains are reported. Large "fusion" proteins containing 4JC domains proved to fall predominantly into family-specific patterns as follows: (1) the 4JC domain was N-terminal; (2) the 4JC domain was C-terminal; (3) the 4JC domain was duplicated or occasionally triplicated and (4) mixed fusion types were present. Our observations provide insight into the evolutionary origins and subfunctions of these proteins as well as guides concerning their structural and functional relationships. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Conductance spectra of asymmetric ferromagnet/ferromagnet/ferromagnet junctions

    Energy Technology Data Exchange (ETDEWEB)

    Pasanai, K., E-mail: krisakronmsu@gmail.com

    2017-01-15

    A theory of tunneling spectroscopy of ferromagnet/ferromagnet/ferromagnet junctions was studied. We applied a delta-functional approximation for the interface scattering properties under a one-dimensional system of a free electron approach. The reflection and transmission probabilities were calculated in the ballistic regime, and the conductance spectra were then calculated using the Landauer formulation. The magnetization directions were set to be either parallel (P) or anti-parallel (AP) alignments, for comparison. We found that the conductance spectra was suppressed when increasing the interfacial scattering at the interfaces. Moreover, the electron could exhibit direct transmission when the thickness was rather thin. Thus, there was no oscillation in this case. However, in the case of a thick layer the conductance spectra oscillated, and this oscillation was most prominent when the middle layer thickness increased. In the case of direct transmission, the conductance spectra of P and AP systems were definitely suppressed with increased exchange energy of the middle ferromagnet. This also refers to an increase in the magnetoresistance of the junction. In the case of oscillatory behavior, the positions of the resonance peaks were changed as the exchange energy was changed. - Highlights: • The conductance spectra of a FM/FM/FM junction were calculated. • The conductance spectra were suppressed by the exchange energy. • The exchange energy and the potential strength play similar roles in the junctions.

  8. Conductance spectra of asymmetric ferromagnet/ferromagnet/ferromagnet junctions

    International Nuclear Information System (INIS)

    Pasanai, K.

    2017-01-01

    A theory of tunneling spectroscopy of ferromagnet/ferromagnet/ferromagnet junctions was studied. We applied a delta-functional approximation for the interface scattering properties under a one-dimensional system of a free electron approach. The reflection and transmission probabilities were calculated in the ballistic regime, and the conductance spectra were then calculated using the Landauer formulation. The magnetization directions were set to be either parallel (P) or anti-parallel (AP) alignments, for comparison. We found that the conductance spectra was suppressed when increasing the interfacial scattering at the interfaces. Moreover, the electron could exhibit direct transmission when the thickness was rather thin. Thus, there was no oscillation in this case. However, in the case of a thick layer the conductance spectra oscillated, and this oscillation was most prominent when the middle layer thickness increased. In the case of direct transmission, the conductance spectra of P and AP systems were definitely suppressed with increased exchange energy of the middle ferromagnet. This also refers to an increase in the magnetoresistance of the junction. In the case of oscillatory behavior, the positions of the resonance peaks were changed as the exchange energy was changed. - Highlights: • The conductance spectra of a FM/FM/FM junction were calculated. • The conductance spectra were suppressed by the exchange energy. • The exchange energy and the potential strength play similar roles in the junctions.

  9. Spin-transfer torque in spin filter tunnel junctions

    KAUST Repository

    Ortiz Pauyac, Christian; Kalitsov, Alan; Manchon, Aurelien; Chshiev, Mairbek

    2014-01-01

    Spin-transfer torque in a class of magnetic tunnel junctions with noncollinear magnetizations, referred to as spin filter tunnel junctions, is studied within the tight-binding model using the nonequilibrium Green's function technique within Keldysh formalism. These junctions consist of one ferromagnet (FM) adjacent to a magnetic insulator (MI) or two FM separated by a MI. We find that the presence of the magnetic insulator dramatically enhances the magnitude of the spin-torque components compared to conventional magnetic tunnel junctions. The fieldlike torque is driven by the spin-dependent reflection at the MI/FM interface, which results in a small reduction of its amplitude when an insulating spacer (S) is inserted to decouple MI and FM layers. Meanwhile, the dampinglike torque is dominated by the tunneling electrons that experience the lowest barrier height. We propose a device of the form FM/(S)/MI/(S)/FM that takes advantage of these characteristics and allows for tuning the spin-torque magnitudes over a wide range just by rotation of the magnetization of the insulating layer.

  10. Spin-transfer torque in spin filter tunnel junctions

    KAUST Repository

    Ortiz Pauyac, Christian

    2014-12-08

    Spin-transfer torque in a class of magnetic tunnel junctions with noncollinear magnetizations, referred to as spin filter tunnel junctions, is studied within the tight-binding model using the nonequilibrium Green\\'s function technique within Keldysh formalism. These junctions consist of one ferromagnet (FM) adjacent to a magnetic insulator (MI) or two FM separated by a MI. We find that the presence of the magnetic insulator dramatically enhances the magnitude of the spin-torque components compared to conventional magnetic tunnel junctions. The fieldlike torque is driven by the spin-dependent reflection at the MI/FM interface, which results in a small reduction of its amplitude when an insulating spacer (S) is inserted to decouple MI and FM layers. Meanwhile, the dampinglike torque is dominated by the tunneling electrons that experience the lowest barrier height. We propose a device of the form FM/(S)/MI/(S)/FM that takes advantage of these characteristics and allows for tuning the spin-torque magnitudes over a wide range just by rotation of the magnetization of the insulating layer.

  11. The psychostimulant modafinil enhances gap junctional communication in cortical astrocytes.

    Science.gov (United States)

    Liu, Xinhe; Petit, Jean-Marie; Ezan, Pascal; Gyger, Joël; Magistretti, Pierre; Giaume, Christian

    2013-12-01

    Sleep-wake cycle is characterized by changes in neuronal network activity. However, for the last decade there is increasing evidence that neuroglial interaction may play a role in the modulation of sleep homeostasis and that astrocytes have a critical impact in this process. Interestingly, astrocytes are organized into communicating networks based on their high expression of connexins, which are the molecular constituents of gap junction channels. Thus, neuroglial interactions should also be considered as the result of the interplay between neuronal and astroglial networks. Here, we investigate the effect of modafinil, a wakefulness-promoting agent, on astrocyte gap junctional communication. We report that in the cortex modafinil injection increases the expression of mRNA and protein of connexin 30 but not those of connexin 43, the other major astroglial connexin. These increases are correlated with an enhancement of intercellular dye coupling in cortical astrocytes, which is abolished when neuronal activity is silenced by tetrodotoxin. Moreover, gamma-hydroxybutyric acid, which at a millimolar concentration induces sleep, has an opposite effect on astroglial gap junctions in an activity-independent manner. These results support the proposition that astroglia may play an important role in complex physiological brain functions, such as sleep regulation, and that neuroglial networking interaction is modified during sleep-wake cycle. This article is part of the Special Issue Section entitled 'Current Pharmacology of Gap Junction Channels and Hemichannels'. Copyright © 2013. Published by Elsevier Ltd.

  12. CSReport: A New Computational Tool Designed for Automatic Analysis of Class Switch Recombination Junctions Sequenced by High-Throughput Sequencing.

    Science.gov (United States)

    Boyer, François; Boutouil, Hend; Dalloul, Iman; Dalloul, Zeinab; Cook-Moreau, Jeanne; Aldigier, Jean-Claude; Carrion, Claire; Herve, Bastien; Scaon, Erwan; Cogné, Michel; Péron, Sophie

    2017-05-15

    B cells ensure humoral immune responses due to the production of Ag-specific memory B cells and Ab-secreting plasma cells. In secondary lymphoid organs, Ag-driven B cell activation induces terminal maturation and Ig isotype class switch (class switch recombination [CSR]). CSR creates a virtually unique IgH locus in every B cell clone by intrachromosomal recombination between two switch (S) regions upstream of each C region gene. Amount and structural features of CSR junctions reveal valuable information about the CSR mechanism, and analysis of CSR junctions is useful in basic and clinical research studies of B cell functions. To provide an automated tool able to analyze large data sets of CSR junction sequences produced by high-throughput sequencing (HTS), we designed CSReport, a software program dedicated to support analysis of CSR recombination junctions sequenced with a HTS-based protocol (Ion Torrent technology). CSReport was assessed using simulated data sets of CSR junctions and then used for analysis of Sμ-Sα and Sμ-Sγ1 junctions from CH12F3 cells and primary murine B cells, respectively. CSReport identifies junction segment breakpoints on reference sequences and junction structure (blunt-ended junctions or junctions with insertions or microhomology). Besides the ability to analyze unprecedentedly large libraries of junction sequences, CSReport will provide a unified framework for CSR junction studies. Our results show that CSReport is an accurate tool for analysis of sequences from our HTS-based protocol for CSR junctions, thereby facilitating and accelerating their study. Copyright © 2017 by The American Association of Immunologists, Inc.

  13. Magnetoresistance of galfenol-based magnetic tunnel junction

    Energy Technology Data Exchange (ETDEWEB)

    Gobaut, B., E-mail: benoit.gobaut@elettra.eu [Sincrotrone Trieste S.C.p.A., S.S. 14 Km 163.5, Area Science Park, 34149 Trieste (Italy); Vinai, G.; Castán-Guerrero, C.; Krizmancic, D.; Panaccione, G.; Torelli, P. [Laboratorio TASC, IOM-CNR, S.S. 14km 163.5, Basovizza, 34149 Trieste (Italy); Rafaqat, H. [Laboratorio TASC, IOM-CNR, S.S. 14km 163.5, Basovizza, 34149 Trieste (Italy); ICTP, Trieste (Italy); Roddaro, S. [Laboratorio TASC, IOM-CNR, S.S. 14km 163.5, Basovizza, 34149 Trieste (Italy); NEST, Scuola Normale Superiore and Istituto Nanoscienze-CNR, Piazza S. Silvestro 12, 56127 Pisa (Italy); Rossi, G. [Laboratorio TASC, IOM-CNR, S.S. 14km 163.5, Basovizza, 34149 Trieste (Italy); Dipartimento di Fisica, Università di Milano, via Celoria 16, 20133 Milano (Italy); Eddrief, M.; Marangolo, M. [Sorbonne Universités, UPMC Paris 06, CNRS-UMR 7588, Institut des Nanosciences de Paris, 75005, Paris (France)

    2015-12-15

    The manipulation of ferromagnetic layer magnetization via electrical pulse is driving an intense research due to the important applications that this result will have on memory devices and sensors. In this study we realized a magnetotunnel junction in which one layer is made of Galfenol (Fe{sub 1-x}Ga{sub x}) which possesses one of the highest magnetostrictive coefficient known. The multilayer stack has been grown by molecular beam epitaxy and e-beam evaporation. Optical lithography and physical etching have been combined to obtain 20x20 micron sized pillars. The obtained structures show tunneling conductivity across the junction and a tunnel magnetoresistance (TMR) effect of up to 11.5% in amplitude.

  14. Field emission current from a junction field-effect transistor

    International Nuclear Information System (INIS)

    Monshipouri, Mahta; Abdi, Yaser

    2015-01-01

    Fabrication of a titanium dioxide/carbon nanotube (TiO 2 /CNT)-based transistor is reported. The transistor can be considered as a combination of a field emission transistor and a junction field-effect transistor. Using direct current plasma-enhanced chemical vapor deposition (DC-PECVD) technique, CNTs were grown on a p-typed (100)-oriented silicon substrate. The CNTs were then covered by TiO 2 nanoparticles 2–5 nm in size, using an atmospheric pressure CVD technique. In this device, TiO 2 /CNT junction is responsible for controlling the emission current. High on/off-current ratio and proper gate control are the most important advantages of device. A model based on Fowler–Nordheim equation is utilized for calculation of the emission current and the results are compared with experimental data. The effect of TiO 2 /CNT hetero-structure is also investigated, and well modeled

  15. Preoperative CT evaluation of adenocarcinoma of the gastroesophageal junction

    International Nuclear Information System (INIS)

    Bennett, J.D.; Lefcoe, M.S.; Finley, R.; Yoshi, C.; Inculet, R.

    1988-01-01

    A retrospective review was undertaken of 53 preoperative computed tomographic (CT) scans obtained between March 1983 and April 1988 from patients undergoing surgery for adenocarcinoma of the gastroesophageal junction, and results were correlated with the surgical-pathologic findings. CT was unreliable in predicting aortic, pericardial, or pancreatic invasion (sensitivity, 0/8; specificity, 41/45). Of 45 pathologically positive nodal groups, the largest node measured on CT scans was 10 mm or less in 36 cases. The accuracy of preoperative CT in staging adenocarcinoma of the gastroesophageal junction is limited by its low sensitivity in detecting local invasion. Nodal size as measured with CT is not a reliable indicator of metastatic disease

  16. Investigating the Variability in Cumulus Cloud Number as a Function of Subdomain Size and Organization using large-domain LES

    Science.gov (United States)

    Neggers, R.

    2017-12-01

    Recent advances in supercomputing have introduced a "grey zone" in the representation of cumulus convection in general circulation models, in which this process is partially resolved. Cumulus parameterizations need to be made scale-aware and scale-adaptive to be able to conceptually and practically deal with this situation. A potential way forward are schemes formulated in terms of discretized Cloud Size Densities, or CSDs. Advantages include i) the introduction of scale-awareness at the foundation of the scheme, and ii) the possibility to apply size-filtering of parameterized convective transport and clouds. The CSD is a new variable that requires closure; this concerns its shape, its range, but also variability in cloud number that can appear due to i) subsampling effects and ii) organization in a cloud field. The goal of this study is to gain insight by means of sub-domain analyses of various large-domain LES realizations of cumulus cloud populations. For a series of three-dimensional snapshots, each with a different degree of organization, the cloud size distribution is calculated in all subdomains, for a range of subdomain sizes. The standard deviation of the number of clouds of a certain size is found to decrease with the subdomain size, following a powerlaw scaling corresponding to an inverse-linear dependence. Cloud number variability also increases with cloud size; this reflects that subsampling affects the largest clouds first, due to their typically larger neighbor spacing. Rewriting this dependence in terms of two dimensionless groups, by dividing by cloud number and cloud size respectively, yields a data collapse. Organization in the cloud field is found to act on top of this primary dependence, by enhancing the cloud number variability at the smaller sizes. This behavior reflects that small clouds start to "live" on top of larger structures such as cold pools, favoring or inhibiting their formation (as illustrated by the attached figure of cloud mask

  17. Statistical flaw strength distributions for glass fibres: Correlation between bundle test and AFM-derived flaw size density functions

    International Nuclear Information System (INIS)

    Foray, G.; Descamps-Mandine, A.; R’Mili, M.; Lamon, J.

    2012-01-01

    The present paper investigates glass fibre flaw size distributions. Two commercial fibre grades (HP and HD) mainly used in cement-based composite reinforcement were studied. Glass fibre fractography is a difficult and time consuming exercise, and thus is seldom carried out. An approach based on tensile tests on multifilament bundles and examination of the fibre surface by atomic force microscopy (AFM) was used. Bundles of more than 500 single filaments each were tested. Thus a statistically significant database of failure data was built up for the HP and HD glass fibres. Gaussian flaw distributions were derived from the filament tensile strength data or extracted from the AFM images. The two distributions were compared. Defect sizes computed from raw AFM images agreed reasonably well with those derived from tensile strength data. Finally, the pertinence of a Gaussian distribution was discussed. The alternative Pareto distribution provided a fair approximation when dealing with AFM flaw size.

  18. Macroscopic quantum tunneling in 1 μm Nb junctions below 100mK

    International Nuclear Information System (INIS)

    Voss, R.F.; Webb, R.A.

    1981-01-01

    The transition probabilities out of the superconducting state of low current density 1 μm Nb Josephson junctions with capacitance < 0.15 pF have been measured as a function of temperature T down to 3 mK. Below 100 mK the distribution widths become independent of T. Junctions with critical currents that differ by an order of magnitude have the same dependence of relative width on T. The low T results are interpreted in terms of quantum tunneling of the (macroscopic) junction phase. The observed low temperature widths are smaller than expected indicating the necessity of corrections to the simple WKB tunneling rates. (orig.)

  19. Realistic-contact-induced enhancement of rectifying in carbon-nanotube/graphene-nanoribbon junctions

    International Nuclear Information System (INIS)

    Zhang, Xiang-Hua; Li, Xiao-Fei; Wang, Ling-Ling; Xu, Liang; Luo, Kai-Wu

    2014-01-01

    Carbon-nanotube/graphene-nanoribbon junctions were recently fabricated by the controllable etching of single-walled carbon-nanotubes [Wei et al., Nat. Commun. 4, 1374 (2013)] and their electronic transport properties were studied here. First principles results reveal that the transmission function of the junctions show a heavy dependence on the shape of contacts, but rectifying is an inherent property which is insensitive to the details of contacts. Interestingly, the rectifying ratio is largely enhanced in the junction with a realistic contact and the enhancement is insensitive to the details of contact structures. The stability of rectifying suggests a significant feasibility to manufacture realistic all-carbon rectifiers in nanoelectronics

  20. Fine structures on zero-field steps in low-loss Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Monaco, Roberto; Barbara, Paola; Mygind, Jesper

    1993-01-01

    The first zero-field step in the current-voltage characteristic of intermediate-length, high-quality, low-loss Nb/Al-AlOx/Nb Josephson tunnel junctions has been carefully investigated as a function of temperature. When decreasing the temperature, a number of structures develop in the form...... of regular and slightly hysteretic steps whose voltage position depends on the junction temperature and length. This phenomenon is interesting for the study of nonlinear dynamics and for application of long Josephson tunnel junctions as microwave and millimeter-wavelength oscillators....

  1. Experimental Evidence for Quantum Interference and Vibrationally Induced Decoherence in Single-Molecule Junctions

    Science.gov (United States)

    Ballmann, Stefan; Härtle, Rainer; Coto, Pedro B.; Elbing, Mark; Mayor, Marcel; Bryce, Martin R.; Thoss, Michael; Weber, Heiko B.

    2012-08-01

    We analyze quantum interference and decoherence effects in single-molecule junctions both experimentally and theoretically by means of the mechanically controlled break junction technique and density-functional theory. We consider the case where interference is provided by overlapping quasidegenerate states. Decoherence mechanisms arising from electronic-vibrational coupling strongly affect the electrical current flowing through a single-molecule contact and can be controlled by temperature variation. Our findings underline the universal relevance of vibrations for understanding charge transport through molecular junctions.

  2. Electrical percolation threshold of magnetostrictive inclusions in a piezoelectric matrix composite as a function of relative particle size

    Science.gov (United States)

    Barbero, Ever J.; Bedard, Antoine Joseph

    2018-04-01

    Magnetoelectric composites can be produced by embedding magnetostrictive particles in a piezoelectric matrix derived from a piezoelectric powder precursor. Ferrite magnetostrictive particles, if allowed to percolate, can short the potential difference generated in the piezoelectric phase. Modeling a magnetoelectric composite as an aggregate of bi-disperse hard shells, molecular dynamics was used to explore relationships among relative particle size, particle affinity, and electrical percolation with the goal of maximizing the percolation threshold. It is found that two factors raise the percolation threshold, namely the relative size of magnetostrictive to piezoelectric particles, and the affinity between the magnetostrictive and piezoelectric particles.

  3. Motion Interplay as a Function of Patient Parameters and Spot Size in Spot Scanning Proton Therapy for Lung Cancer

    International Nuclear Information System (INIS)

    Grassberger, Clemens; Dowdell, Stephen; Lomax, Antony; Sharp, Greg; Shackleford, James; Choi, Noah; Willers, Henning; Paganetti, Harald

    2013-01-01

    Purpose: To quantify the impact of respiratory motion on the treatment of lung tumors with spot scanning proton therapy. Methods and Materials: Four-dimensional Monte Carlo simulations were used to assess the interplay effect, which results from relative motion of the tumor and the proton beam, on the dose distribution in the patient. Ten patients with varying tumor sizes (2.6-82.3 cc) and motion amplitudes (3-30 mm) were included in the study. We investigated the impact of the spot size, which varies between proton facilities, and studied single fractions and conventionally fractionated treatments. The following metrics were used in the analysis: minimum/maximum/mean dose, target dose homogeneity, and 2-year local control rate (2y-LC). Results: Respiratory motion reduces the target dose homogeneity, with the largest effects observed for the highest motion amplitudes. Smaller spot sizes (σ ≈ 3 mm) are inherently more sensitive to motion, decreasing target dose homogeneity on average by a factor 2.8 compared with a larger spot size (σ ≈ 13 mm). Using a smaller spot size to treat a tumor with 30-mm motion amplitude reduces the minimum dose to 44.7% of the prescribed dose, decreasing modeled 2y-LC from 87.0% to 2.7%, assuming a single fraction. Conventional fractionation partly mitigates this reduction, yielding a 2y-LC of 71.6%. For the large spot size, conventional fractionation increases target dose homogeneity and prevents a deterioration of 2y-LC for all patients. No correlation with tumor volume is observed. The effect on the normal lung dose distribution is minimal: observed changes in mean lung dose and lung V 20 are <0.6 Gy(RBE) and <1.7%, respectively. Conclusions: For the patients in this study, 2y-LC could be preserved in the presence of interplay using a large spot size and conventional fractionation. For treatments using smaller spot sizes and/or in the delivery of single fractions, interplay effects can lead to significant deterioration of the

  4. Doubled Shapiro steps in a topological Josephson junction

    Science.gov (United States)

    Li, Yu-Hang; Song, Juntao; Liu, Jie; Jiang, Hua; Sun, Qing-Feng; Xie, X. C.

    2018-01-01

    We study the transport properties of a superconductor-quantum spin Hall insulator-superconductor hybrid system in the presence of microwave radiation. Instead of adiabatic analysis or use of the resistively shunted junction model, we start from the microscopic Hamiltonian and calculate the d.c. current directly with the help of the nonequilibrium Green's function method. The numerical results show that (i) the I-V curves of background current due to multiple Andreev reflections exhibit a different structure from those in the conventional junctions, and (ii) all Shapiro steps are visible and appear one by one at high frequencies, while at low frequencies, the steps evolve exactly as the Bessel functions and the odd steps are completely suppressed, implying a fractional Josephson effect.

  5. Ribosomal protein NtRPL17 interacts with kinesin-12 family protein NtKRP and functions in the regulation of embryo/seed size and radicle growth.

    Science.gov (United States)

    Tian, Shujuan; Wu, Jingjing; Liu, Yuan; Huang, Xiaorong; Li, Fen; Wang, Zhaodan; Sun, Meng-Xiang

    2017-11-28

    We previously reported that a novel motor protein belonging to the kinesin-12 family, NtKRP, displays critical roles in regulating embryo and seed size establishment. However, it remains unknown exactly how NtKRP contributes to this developmental process. Here, we report that a 60S ribosomal protein NtRPL17 directly interacts with NtKRP. The phenotypes of NtRPL17 RNAi lines show notable embryo and seed size reduction. Structural observations of the NtRPL17-silenced embryos/seeds reveal that the embryo size reduction is due to a decrease in cell number. In these embryos, cell division cycle progression is delayed at the G2/M transition. These phenotypes are similar to that in NtKRP-silenced embryos/seeds, indicating that NtKRP and NtRPL17 function as partners in the same regulatory pathway during seed development and specifically regulate cell cycle progression to control embryo/seed size. This work reveals that NtRPL17, as a widely distributed ribosomal protein, plays a critical role in seed development and provides a new clue in the regulation of seed size. Confirmation of the interaction between NtKRP and NtRPL17 and their co-function in the control of the cell cycle also suggests that the mechanism might be conserved in both plants and animals. © The Author 2017. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  6. Effect of dietary fiber and diet particle size on nutrient digestibility and gastrointestinal secretory function in growing pigs

    Science.gov (United States)

    Effect of diet composition (DC) and particle size (PS) on nutrient digestibility, gastrointestinal hormones, total bile acids (TBA), total cholesterol and glucose concentrations in plasma were evaluated in finishing pigs (n=8/diet) fed finely (374±29 µm) or coarsely (631±35 µm) ground corn-soybean m...

  7. Ultrasonic attenuation as a function of heat treatment and grain size in 79Ni--6Mo--15Fe alloy

    International Nuclear Information System (INIS)

    Gieske, J.H.

    1978-03-01

    A pulse echo ultrasonic technique was used to measure the attenuation coefficient for 79Ni-6Mo-15Fe alloy specimens. The attenuation coefficient was determined using a 25 MHz ultrasonic transducer for specimens which had undergone different time-temperature heat treatments. The ultrasonic attenuation data versus heat treat time was used to assess grain size growth in the specimens

  8. Assessment of tricuspid valve annulus size, shape and function using real-time three-dimensional echocardiography

    NARCIS (Netherlands)

    A.M. Anwar (Ashraf); M.L. Geleijnse (Marcel); F.J. ten Cate (Folkert); F.J. Meijboom (Folkert)

    2006-01-01

    textabstractTricuspid annulus (TA) evaluation continues to be a major problem in the surgical decision-making process. Obviously, 2-dimensional transthoracic echocardiography (2D TTE) is limited in TA visualization due to its complex 3D shape. The study aimed to determine TA morphology, size and

  9. The influence of lifestyle, menstrual function and oral contraceptive use on bone mass and size in female military cadets

    Directory of Open Access Journals (Sweden)

    Tendy Susan

    2007-08-01

    Full Text Available Abstract Purpose To determine the influence of menstrual irregularity, oral contraceptive use and other factors on bone mineral density (BMD and bone size at different skeletal sites in 135 college-aged fit women. Methods Menstrual history, oral contraceptive use, exercise history, and nutritional factors including calcium, caffeine, and alcohol intake as well as tobacco use were determined by written survey. Height, weight and fitness levels were measured. Spine and hip BMD were measured by dual x-ray absorptiometry (DXA, calcaneus BMD by peripheral DXA, and tibial bone mineral content (BMC and size by peripheral Quantitative Computed Tomography (pQCT. Results The mean age was 18.4 ± 0.8 years. Weight and prior exercise were positively related to BMD at most skeletal sites and to tibial bone size. Milk intake was positively related to calcaneal BMD, tibial BMC and cortical thickness. Fracture history was an important predictor of spine, hip and heel BMD. Women who had ≥ 10 menstrual cycles in the year prior to BMD measurement had higher BMD at all sites as well as a greater tibial mineral content and cortical thickness than women who had oligomenorrhea/amenorrhea (≤ 9 cycles in the prior year; all p p p = 0.04, smaller tibial periosteal circumference and lower tibial mineral content (p Conclusion In a population of fit, college-aged women, OC use and oligomenorrhea were associated with reduced BMD and bone size. Weight, as well as prior exercise and milk intake was positively related to bone density and size at some skeletal sites. Understanding these relationships would help improve skeletal health in young women.

  10. Linker-dependent Junction Formation Probability in Single-Molecule Junctions

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Pil Sun; Kim, Taekyeong [HankukUniversity of Foreign Studies, Yongin (Korea, Republic of)

    2015-01-15

    We compare the junction formation probabilities of single-molecule junctions with different linker molecules by using a scanning tunneling microscope-based break-junction technique. We found that the junction formation probability varies as SH > SMe > NH2 for the benzene backbone molecule with different types of anchoring groups, through quantitative statistical analysis. These results are attributed to different bonding forces according to the linker groups formed with Au atoms in the electrodes, which is consistent with previous works. Our work allows a better understanding of the contact chemistry in the metal.molecule junction for future molecular electronic devices.

  11. Intracellular trafficking pathways of Cx43 gap junction channels.

    Science.gov (United States)

    Epifantseva, Irina; Shaw, Robin M

    2018-01-01

    Gap Junction (GJ) channels, including the most common Connexin 43 (Cx43), have fundamental roles in excitable tissues by facilitating rapid transmission of action potentials between adjacent cells. For instance, synchronization during each heartbeat is regulated by these ion channels at the cardiomyocyte cell-cell border. Cx43 protein has a short half-life, and rapid synthesis and timely delivery of those proteins to particular subdomains are crucial for the cellular organization of gap junctions and maintenance of intracellular coupling. Impairment in gap junction trafficking contributes to dangerous complications in diseased hearts such as the arrhythmias of sudden cardiac death. Of recent interest are the protein-protein interactions with the Cx43 carboxy-terminus. These interactions have significant impact on the full length Cx43 lifecycle and also contribute to trafficking of Cx43 as well as possibly other functions. We are learning that many of the known non-canonical roles of Cx43 can be attributed to the recently identified six endogenous Cx43 truncated isoforms which are produced by internal translation. In general, alternative translation is a new leading edge for proteome expansion and therapeutic drug development. This review highlights recent mechanisms identified in the trafficking of gap junction channels, involvement of other proteins contributing to the delivery of channels to the cell-cell border, and understanding of possible roles of the newly discovered alternatively translated isoforms in Cx43 biology. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Cavity syncronisation of underdamped Josephson junction arrays

    DEFF Research Database (Denmark)

    Barbara, P.; Filatrella, G.; Lobb, C.

    2003-01-01

    the junctions in the array and an electromagnetic cavity. Here we show that a model of a one-dimensional array of Josephson junctions coupled to a resonator can produce many features of the coherent be havior above threshold, including coherent radiation of power and the shape of the array current...

  13. Spin, Vibrations and Radiation in Superconducting Junctions

    NARCIS (Netherlands)

    Padurariu, C.

    2013-01-01

    This thesis presents the theoretical study of superconducting transport in several devices based on superconducting junctions. The important feature of these devices is that the transport properties of the junction are modified by the interaction with another physical system integrated in the

  14. Gap junctions and connexin-interacting proteins

    NARCIS (Netherlands)

    Giepmans, Ben N G

    2004-01-01

    Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the

  15. Multiplication in Silicon p-n Junctions

    DEFF Research Database (Denmark)

    Moll, John L.

    1965-01-01

    Multiplication values were measured in the collector junctions of silicon p-n-p and n-p-n transistors before and after bombardment by 1016 neutrons/cm2. Within experimental error there was no change either in junction fields, as deduced from capacitance measurements, or in multiplication values i...

  16. The GH/IGF-I axis and pituitary function and size in adults with Prader-Willi syndrome

    NARCIS (Netherlands)

    van Nieuwpoort, I.C.; Sinnema, M.; Castelijns, J.A.; Twisk, J.W.; Curfs, L.M.; Drent, M.L.

    2011-01-01

    Background: In adults with Prader-Willi syndrome (PWS), limited information is available about pituitary function, more specifically the prevalence of growth hormone deficiency (GHD). The aim of this study was to gain more insight into endocrine function in PWS adults, with emphasis on GH secretion.

  17. Fabrication of Josephson Junction without shadow evaporation

    Science.gov (United States)

    Wu, Xian; Ku, Hsiangsheng; Long, Junling; Pappas, David

    We developed a new method of fabricating Josephson Junction (Al/AlOX/Al) without shadow evaporation. Statistics from room temperature junction resistance and measurement of qubits are presented. Unlike the traditional ``Dolan Bridge'' technique, this method requires two individual lithographies and straight evaporations of Al. Argon RF plasma is used to remove native AlOX after the first evaporation, followed by oxidation and second Al evaporation. Junction resistance measured at room temperature shows linear dependence on Pox (oxidation pressure), √{tox} (oxidation time), and inverse proportional to junction area. We have seen 100% yield of qubits made with this method. This method is promising because it eliminates angle dependence during Junction fabrication, facilitates large scale qubits fabrication.

  18. Overlap junctions for high coherence superconducting qubits

    Science.gov (United States)

    Wu, X.; Long, J. L.; Ku, H. S.; Lake, R. E.; Bal, M.; Pappas, D. P.

    2017-07-01

    Fabrication of sub-micron Josephson junctions is demonstrated using standard processing techniques for high-coherence, superconducting qubits. These junctions are made in two separate lithography steps with normal-angle evaporation. Most significantly, this work demonstrates that it is possible to achieve high coherence with junctions formed on aluminum surfaces cleaned in situ by Ar plasma before junction oxidation. This method eliminates the angle-dependent shadow masks typically used for small junctions. Therefore, this is conducive to the implementation of typical methods for improving margins and yield using conventional CMOS processing. The current method uses electron-beam lithography and an additive process to define the top and bottom electrodes. Extension of this work to optical lithography and subtractive processes is discussed.

  19. Quantum synchronization effects in intrinsic Josephson junctions

    International Nuclear Information System (INIS)

    Machida, M.; Kano, T.; Yamada, S.; Okumura, M.; Imamura, T.; Koyama, T.

    2008-01-01

    We investigate quantum dynamics of the superconducting phase in intrinsic Josephson junctions of layered high-T c superconductors motivated by a recent experimental observation for the switching rate enhancement in the low temperature quantum regime. We pay attention to only the capacitive coupling between neighboring junctions and perform large-scale simulations for the Schroedinger equation derived from the Hamiltonian considering the capacitive coupling alone. The simulation focuses on an issue whether the switching of a junction induces those of the other junctions or not. The results reveal that the superconducting phase dynamics show synchronous behavior with increasing the quantum character, e.g., decreasing the junction plane area and effectively the temperature. This is qualitatively consistent with the experimental result

  20. TH-C-BRD-12: Robust Intensity Modulated Proton Therapy Plan Can Eliminate Junction Shifts for Craniospinal Irradiation

    International Nuclear Information System (INIS)

    Liao, L; Jiang, S; Li, Y; Wang, X; Li, H; Zhu, X; Sahoo, N; Gillin, M; Mahajan, A; Grosshans, D; Zhang, X; Lim, G

    2014-01-01

    Purpose: The passive scattering proton therapy (PSPT) technique is the commonly used radiotherapy technique for craniospinal irradiation (CSI). However, PSPT involves many numbers of junction shifts applied over the course of treatment to reduce the cold and hot regions caused by field mismatching. In this work, we introduced a robust planning approach to develop an optimal and clinical efficient techniques for CSI using intensity modulated proton therapy (IMPT) so that junction shifts can essentially be eliminated. Methods: The intra-fractional uncertainty, in which two overlapping fields shift in the opposite directions along the craniospinal axis, are incorporated into the robust optimization algorithm. Treatment plans with junction sizes 3,5,10,15,20,25 cm were designed and compared with the plan designed using the non-robust optimization. Robustness of the plans were evaluated based on dose profiles along the craniospinal axis for the plans applying 3 mm intra-fractional shift. The dose intra-fraction variations (DIV) at the junction are used to evaluate the robustness of the plans. Results: The DIVs are 7.9%, 6.3%, 5.0%, 3.8%, 2.8% and 2.2%, for the robustly optimized plans with junction sizes 3,5,10,15,20,25 cm. The DIV are 10% for the non-robustly optimized plans with junction size 25 cm. The dose profiles along the craniospinal axis exhibit gradual and tapered dose distribution. Using DIVs less than 5% as maximum acceptable intrafractional variation, the overlapping region can be reduced to 10 cm, leading to potential reduced number of the fields. The DIVs are less than 5% for 5 mm intra-fractional shifts with junction size 25 cm, leading to potential no-junction-shift for CSI using IMPT. Conclusion: This work is the first report of the robust optimization on CSI based on IMPT. We demonstrate that robust optimization can lead to much efficient carniospinal irradiation by eliminating the junction shifts

  1. Feeding behaviour of the nauplii of the marine calanoid copepod Paracartia grani Sars: Functional response, prey size spectrum, and effects of the presence of alternative prey.

    Directory of Open Access Journals (Sweden)

    Laura K Helenius

    Full Text Available Laboratory feeding experiments were conducted to study the functional response and prey size spectrum of the young naupliar stages of the calanoid copepod Paracartia grani Sars. Experiments were conducted on a range of microalgal prey of varying sizes and motility patterns. Significant feeding was found in all prey of a size range of 4.5-19.8 μm, with Holling type III functional responses observed for most prey types. The highest clearance rates occurred when nauplii fed on the dinoflagellate Heterocapsa sp. and the diatom Thalassiosira weissflogii (respectively, 0.61 and 0.70 mL ind-1 d-1, suggesting an optimal prey:predator ratio of 0.09. Additional experiments were conducted to examine the effects of the presence of alternative prey (either Heterocapsa sp. or Gymnodinium litoralis on the functional response to the haptophyte Isochrysis galbana. In the bialgal mixtures, clearance and ingestion rates of I. galbana along the range of the functional response were significantly reduced as a result of selectivity towards the larger, alternative prey. Paradoxically, relatively large prey trigger a perception response in the nauplii, but most likely such prey cannot be completely ingested and a certain degree of sloppy feeding may occur. Our results are further evidence of the complex prey-specific feeding interactions that are likely to occur in natural assemblages with several available prey types.

  2. Innovative architecture design for high performance organic and hybrid multi-junction solar cells

    Science.gov (United States)

    Li, Ning; Spyropoulos, George D.; Brabec, Christoph J.

    2017-08-01

    The multi-junction concept is especially attractive for the photovoltaic (PV) research community owing to its potential to overcome the Schockley-Queisser limit of single-junction solar cells. Tremendous research interests are now focused on the development of high-performance absorbers and novel device architectures for emerging PV technologies, such as organic and perovskite PVs. It has been predicted that the multi-junction concept is able to boost the organic and perovskite PV technologies approaching the 20% and 30% benchmarks, respectively, showing a bright future of commercialization of the emerging PV technologies. In this contribution, we will demonstrate innovative architecture design for solution-processed, highly functional organic and hybrid multi-junction solar cells. A simple but elegant approach to fabricating organic and hybrid multi-junction solar cells will be introduced. By laminating single organic/hybrid solar cells together through an intermediate layer, the manufacturing cost and complexity of large-scale multi-junction solar cells can be significantly reduced. This smart approach to balancing the photocurrents as well as open circuit voltages in multi-junction solar cells will be demonstrated and discussed in detail.

  3. Genetic differentiation for size at first reproduction through male versus female functions in the widespread Mediterranean tree Pinus pinaster

    OpenAIRE

    Santos-del-Blanco, L.; Climent, J.; González-Martínez, S. C.; Pannell, J. R.

    2012-01-01

    Background and Aims The study of local adaptation in plant reproductive traits has received substantial attention in short-lived species, but studies conducted on forest trees are scarce. This lack of research on long-lived species represents an important gap in our knowledge, because inferences about selection on the reproduction and life history of short-lived species cannot necessarily be extrapolated to trees. This study considers whether the size for first reproduction is locally adapted...

  4. Fermentation pH Modulates the Size Distributions and Functional Properties of Gluconobacter albidus TMW 2.1191 Levan

    Directory of Open Access Journals (Sweden)

    Tharalinee Ua-Arak

    2017-05-01

    Full Text Available Bacterial levan has gained an increasing interest over the last decades due to its unique characteristics and multiple possible applications. Levan and other exopolysaccharides (EPSs production are usually optimized to obtain the highest concentration or yield while a possible change of the molecular size and mass during the production process is mostly neglected. In this study, the molar mass and radius of levan samples were monitored during fermentations with the food-grade, levan-producing acetic acid bacterium Gluconobacter (G. albidus TMW 2.1191 in shake flasks (without pH control and bioreactors (with pH control at 4.5, 5.5 and 6.5, respectively. In uncontrolled fermentations, the levan size/molar mass continuously decreased concomitantly with the continuous acidification of the nutrient medium. On the contrary, the amount, molar mass and size of levan could be directly influenced by controlling the pH during fermentation. Using equal initial substrate amounts, the largest weight average molar mass and geometric radius of levan were observed at constant pH 6.5, while the highest levan concentration was obtained at constant pH 4.5. Since there is a special demand to find suitable hydrocolloids from food-grade bacteria to develop novel gluten-free (GF products, these differently produced levans were used for baking of GF breads, and the best quality improvement was obtained by addition of levan with the highest mass and radius. This work, therefore, demonstrates for the first time that one bacterial strain can produce specific high molecular weight fractions of one EPS type, which differ in properties and sizes among each other in dependence of the controllable production conditions.

  5. Macroscopic quantum tunneling in Josephson tunnel junctions and Coulomb blockade in single small tunnel junctions

    International Nuclear Information System (INIS)

    Cleland, A.N.

    1991-04-01

    Experiments investigating the process of macroscopic quantum tunneling in a moderately-damped, resistively shunted, Josephson junction are described, followed by a discussion of experiments performed on very small capacitance normal-metal tunnel junctions. The experiments on the resistively-shunted Josephson junction were designed to investigate a quantum process, that of the tunneling of the Josephson phase variable under a potential barrier, in a system in which dissipation plays a major role in the dynamics of motion. All the parameters of the junction were measured using the classical phenomena of thermal activation and resonant activation. Theoretical predictions are compared with the experimental results, showing good agreement with no adjustable parameters; the tunneling rate in the moderately damped (Q ∼ 1) junction is seen to be reduced by a factor of 300 from that predicted for an undamped junction. The phase is seen to be a good quantum-mechanical variable. The experiments on small capacitance tunnel junctions extend the measurements on the larger-area Josephson junctions from the region in which the phase variable has a fairly well-defined value, i.e. its wavefunction has a narrow width, to the region where its value is almost completely unknown. The charge on the junction becomes well-defined and is predicted to quantize the current through the junction, giving rise to the Coulomb blockade at low bias. I present the first clear observation of the Coulomb blockade in single junctions. The electrical environment of the tunnel junction, however, strongly affects the behavior of the junction: higher resistance leads are observed to greatly sharpen the Coulomb blockade over that seen with lower resistance leads. I present theoretical descriptions of how the environment influences the junctions; comparisons with the experimental results are in reasonable agreement

  6. Resonance Transport of Graphene Nanoribbon T-Shaped Junctions

    International Nuclear Information System (INIS)

    Xiao-Lan, Kong; Yong-Jian, Xiong

    2010-01-01

    We investigate the transport properties of T-shaped junctions composed of armchair graphene nanoribbons of different widths. Three types of junction geometries are considered. The junction conductance strongly depends on the atomic features of the junction geometry. When the shoulders of the junction have zigzag type edges, sharp conductance resonances usually appear in the low energy region around the Dirac point, and a conductance gap emerges. When the shoulders of the junction have armchair type edges, the conductance resonance behavior is weakened significantly, and the metal-metal-metal junction structures show semimetallic behaviors. The contact resistance also changes notably due to the various interface geometries of the junction

  7. Perturbation treatment of mixing in Josephson junctions

    International Nuclear Information System (INIS)

    Levinsen, M.T.; Ulrich, B.T.

    1975-01-01

    A current biased, resistively shunted Josephson Junction irradiated at two frequencies is considered. The perturbation technique introduced by Aslamasov and Larkin is used in the calculations, and both signals are treated as perturbations. The second order calculation yields the size of the mixing steps at V/sub +-/ = h(ω 1 +- ω 2 )/2e. As in the case of a single frequency, subharmonic mixing steps are absent. The amplitude of the voltage oscillation at the difference and sum frequencies is shown to be non-zero at all voltages. The microwave resistance is calculated for one frequency ω 2 to third order in the perturbation. There are negative resistance regions near V/sub +-/ (as well as near V 2 = hω 2 /2e). Near V/sub -/, the negative resistance region appears for bias voltage V just above V/sub -/, while near V the region appears for V just below V/sub +/. This means that when an incident frequency mixes with a cavity mode, the mixing step at V/sub -/ will be inverted compared to the cavity step itself

  8. Connexin 43 Expression on Peripheral Blood Eosinophils: Role of Gap Junctions in Transendothelial Migration

    Directory of Open Access Journals (Sweden)

    Harissios Vliagoftis

    2014-01-01

    Full Text Available Eosinophils circulate in the blood and are recruited in tissues during allergic inflammation. Gap junctions mediate direct communication between adjacent cells and may represent a new way of communication between immune cells distinct from communication through cytokines and chemokines. We characterized the expression of connexin (Cx43 by eosinophils isolated from atopic individuals using RT-PCR, Western blotting, and confocal microscopy and studied the biological functions of gap junctions on eosinophils. The formation of functional gap junctions was evaluated measuring dye transfer using flow cytometry. The role of gap junctions on eosinophil transendothelial migration was studied using the inhibitor 18-a-glycyrrhetinic acid. Peripheral blood eosinophils express Cx43 mRNA and protein. Cx43 is localized not only in the cytoplasm but also on the plasma membrane. The membrane impermeable dye BCECF transferred from eosinophils to epithelial or endothelial cells following coculture in a dose and time dependent fashion. The gap junction inhibitors 18-a-glycyrrhetinic acid and octanol did not have a significant effect on dye transfer but reduced dye exit from eosinophils. The gap junction inhibitor 18-a-glycyrrhetinic acid inhibited eosinophil transendothelial migration in a dose dependent manner. Thus, eosinophils from atopic individuals express Cx43 constitutively and Cx43 may play an important role in eosinophil transendothelial migration and function in sites of inflammation.

  9. Intercellular communication via gap junctions affected by mechanical load in the bovine annulus fibrosus.

    Science.gov (United States)

    Desrochers, Jane; Duncan, Neil A

    2014-01-01

    Cells in the intervertebral disc, as in other connective tissues including tendon, ligament and bone, form interconnected cellular networks that are linked via functional gap junctions. These cellular networks may be necessary to affect a coordinated response to mechanical and environmental stimuli. Using confocal microscopy with fluorescence recovery after photobleaching methods, we explored the in situ strain environment of the outer annulus of an intact bovine disc and the effect of high-level flexion on gap junction signalling. The in situ strain environment in the extracellular matrix of the outer annulus under high flexion load was observed to be non-uniform with the extensive cellular processes remaining crimped sometimes at flexion angles greater than 25°. A significant transient disruption of intercellular communication via functional gap junctions was measured after 10 and 20 min under high flexion load. This study illustrates that in healthy annulus fibrosus tissue, high mechanical loads can impede the functioning of the gap junctions. Future studies will explore more complex loading conditions to determine whether losses in intercellular communication can be permanent and whether gap junctions in aged and degenerated tissues become more susceptible to load. The current research suggests that cellular structures such as gap junctions and intercellular networks, as well as other cell-cell and cell-matrix interconnections, need to be considered in computational models in order to fully understand how macroscale mechanical signals are transmitted across scales to the microscale and ultimately into a cellular biosynthetic response in collagenous tissues.

  10. Inter-assemblage facilitation: the functional diversity of cavity-producing beetles drives the size diversity of cavity-nesting bees.

    Science.gov (United States)

    Sydenham, Markus A K; Häusler, Lise D; Moe, Stein R; Eldegard, Katrine

    2016-01-01

    Inter-specific interactions are important drivers and maintainers of biodiversity. Compared to trophic and competitive interactions, the role of non-trophic facilitation among species has received less attention. Cavity-nesting bees nest in old beetle borings in dead wood, with restricted diameters corresponding to the body size of the bee species. The aim of this study was to test the hypothesis that the functional diversity of cavity-producing wood boring beetles - in terms of cavity diameters - drives the size diversity of cavity-nesting bees. The invertebrate communities were sampled in 30 sites, located in forested landscapes along an elevational gradient. We regressed the species richness and abundance of cavity nesting bees against the species richness and abundance of wood boring beetles, non-wood boring beetles and elevation. The proportion of cavity nesting bees in bee species assemblage was regressed against the species richness and abundance of wood boring beetles. We also tested the relationships between the size diversity of cavity nesting bees and wood boring beetles. The species richness and abundance of cavity nesting bees increased with the species richness and abundance of wood boring beetles. No such relationship was found for non-wood boring beetles. The abundance of wood boring beetles was also related to an increased proportion of cavity nesting bee individuals. Moreover, the size diversity of cavity-nesting bees increased with the functional diversity of wood boring beetles. Specifically, the mean and dispersion of bee body sizes increased with the functional dispersion of large wood boring beetles. The positive relationships between cavity producing bees and cavity nesting bees suggest that non-trophic facilitative interactions between species assemblages play important roles in organizing bee species assemblages. Considering a community-wide approach may therefore be required if we are to successfully understand and conserve wild bee

  11. Droplet formation in Hele-Shaw T-junction.

    Science.gov (United States)

    Ricouvier, Joshua; Yazhgur, Pavel; Leshansky, Alexander; Tabeling, Patrick; Microflusa Team

    The development of digital microfluidics has attracted considerable interest towards generation of highly monodisperse microdroplets. T-junction has become an essential element of most of microfluidic chips. Despite its importance, theoretical analysis of droplet formation at T-junction is still incomplete due to complexity of physics involved. We focused on droplet generation at the Hele-Shaw T-junction. The effect of various experimental parameters, such as channel geometry, flow rates, surface tension and fluid viscosities, was thoroughly investigated. Our results show that the experimental system exhibits three distinct regimes (squeezing, dripping and jetting regimes) and point out the effect of confinement on the transitions. We demonstrate that the size of the ''plug'' droplet depends not only on the flow rate ratio (as described in the literature), but also on the capillary number and the channel cross-section aspect ratio. Quasi-2D flow equations allow us to perform numerical simulations and to compare them with experimental results. The Microflusa project receives funding from the European Union's Horizon 2020 research and innovation programme under Grant Agreement No. 664823.

  12. Pulse-voltammetric glucose detection at gold junction electrodes.

    Science.gov (United States)

    Rassaei, Liza; Marken, Frank

    2010-09-01

    A novel glucose sensing concept based on the localized change or "modulation" in pH within a symmetric gold-gold junction electrode is proposed. A paired gold-gold junction electrode (average gap size ca. 500 nm) is prepared by simultaneous bipotentiostatic electrodeposition of gold onto two closely spaced platinum disk electrodes. For glucose detection in neutral aqueous solution, the potential of the "pH-modulator" electrode is set to -1.5 V vs saturated calomel reference electrode (SCE) to locally increase the pH, and simultaneously, either cyclic voltammetry or square wave voltammetry experiments are conducted at the sensor electrode. A considerable improvement in the sensor electrode response is observed when a normal pulse voltammetry sequence is applied to the modulator electrode (to generate "hydroxide pulses") and the glucose sensor electrode is operated with fixed bias at +0.5 V vs SCE (to eliminate capacitive charging currents). Preliminary data suggest good linearity for the glucose response in the medically relevant 1-10 mM concentration range (corresponding to 0.18-1.8 g L(-1)). Future electroanalytical applications of multidimensional pulse voltammetry in junction electrodes are discussed.

  13. An Efficient Solution-Processed Intermediate Layer for Facilitating Fabrication of Organic Multi-Junction Solar Cells

    DEFF Research Database (Denmark)

    Ning Li; Baran, Derya; Forberich, Karen

    2013-01-01

    ):poly(styrenesulfonate) (PEDOT:PSS) is demonstrated for series-connected multi-junction organic solar cells (OSCs). Drying at 80 °C in air is sufficient for this solution-processed IML to obtain excellent functionality and reliability, which allow the use of most of high performance donor materials in the tandem structure....... An open circuit voltage (Voc) of 0.56 V is obtained for single-junction OSCs based on a low band-gap polymer, while multi-junction OSCs based on the same absorber material deliver promising fill factor values along with fully additive Voc as the number of junctions increase. Optical and electrical...... simulations, which are reliable and promising guidelines for the design and investigation of multi-junction OSCs, are discussed. The outcome of optical and electrical simulations is in excellent agreement with the experimental data, indicating the outstanding efficiency and functionality of this solution...

  14. Protein kinase C isoforms at the neuromuscular junction: localization and specific roles in neurotransmission and development.

    Science.gov (United States)

    Lanuza, Maria A; Santafe, Manel M; Garcia, Neus; Besalduch, Núria; Tomàs, Marta; Obis, Teresa; Priego, Mercedes; Nelson, Phillip G; Tomàs, Josep

    2014-01-01

    The protein kinase C family (PKC) regulates a variety of neural functions including neurotransmitter release. The selective activation of a wide range of PKC isoforms in different cells and domains is likely to contribute to the functional diversity of PKC phosphorylating activity. In this review, we describe the isoform localization, phosphorylation function, regulation and signalling of the PKC family at the neuromuscular junction. Data show the involvement of the PKC family in several important functions at the neuromuscular junction and in particular in the maturation of the synapse and the modulation of neurotransmission in the adult. © 2013 Anatomical Society.

  15. 7-Ketocholesterol modulates intercellular communication through gap-junction in bovine lens epithelial cells

    Directory of Open Access Journals (Sweden)

    Pereira Paulo

    2004-06-01

    Full Text Available Abstract Background Connexin43 (Cx43 is an integral membrane protein that forms intercellular channels called gap junctions. Intercellular communication in the eye lens relies on an extensive network of gap junctions essential for the maintenance of lens transparency. The association of Cx43 with cholesterol enriched lipid raft domains was recently demonstrated. The objective of this study is to assess if products of cholesterol oxidation (oxysterols affect gap junction intercellular communication (GJIC. Results Primary cultures of lens epithelial cells (LEC were incubated with 7-ketocholesterol (7-Keto, 25-hydroxycholesterol (25-OH or cholesterol and the subcellular distribution of Cx43 was evaluated by immunofluorescence confocal microscopy. The levels of Cx43 present in gap junction plaques were assessed by its insolubility in Triton X-100 and quantified by western blotting. The stability of Cx43 at the plasma membrane following incubation with oxysterols was evaluated by biotinylation of cell surface proteins. Gap junction intercellular communication was evaluated by transfer of the dye Lucifer yellow. The results obtained showed that 7-keto induces an accumulation of Cx43 at the plasma membrane and an increase in intercellular communication through gap junction. However, incubation with cholesterol or 25-OH did not lead to significant alterations on subcellular distribution of Cx43 nor in intercellular communication. Data further suggests that increased intercellular communication results from increased stability of Cx43 at the plasma membrane, presumably forming functional gap-junctions, as suggested by decreased solubility of Cx43 in 1% Triton X-100. The increased stability of Cx43 at the plasma membrane seems to be specific and not related to disruption of endocytic pathway, as demonstrated by dextran uptake. Conclusions Results demonstrate, for the first time, that 7-keto induces an increase in gap junction intercellular communication

  16. Predictive modelling of grain size distributions from marine electromagnetic profiling data using end-member analysis and a radial basis function network

    Science.gov (United States)

    Baasch, B.; M"uller, H.; von Dobeneck, T.

    2018-04-01

    In this work we present a new methodology to predict grain-size distributions from geophysical data. Specifically, electric conductivity and magnetic susceptibility of seafloor sediments recovered from electromagnetic profiling data are used to predict grain-size distributions along shelf-wide survey lines. Field data from the NW Iberian shelf are investigated and reveal a strong relation between the electromagnetic properties and grain-size distribution. The here presented workflow combines unsupervised and supervised machine learning techniques. Nonnegative matrix factorisation is used to determine grain-size end-members from sediment surface samples. Four end-members were found which well represent the variety of sediments in the study area. A radial-basis function network modified for prediction of compositional data is then used to estimate the abundances of these end-members from the electromagnetic properties. The end-members together with their predicted abundances are finally back transformed to grain-size distributions. A minimum spatial variation constraint is implemented in the training of the network to avoid overfitting and to respect the spatial distribution of sediment patterns. The predicted models are tested via leave-one-out cross-validation revealing high prediction accuracy with coefficients of determination (R2) between 0.76 and 0.89. The predicted grain-size distributions represent the well-known sediment facies and patterns on the NW Iberian shelf and provide new insights into their distribution, transition and dynamics. This study suggests that electromagnetic benthic profiling in combination with machine learning techniques is a powerful tool to estimate grain-size distribution of marine sediments.

  17. Handedness- and brain size-related efficiency differences in small-world brain networks: a resting-state functional magnetic resonance imaging study.

    Science.gov (United States)

    Li, Meiling; Wang, Junping; Liu, Feng; Chen, Heng; Lu, Fengmei; Wu, Guorong; Yu, Chunshui; Chen, Huafu

    2015-05-01

    The human brain has been described as a complex network, which integrates information with high efficiency. However, the relationships between the efficiency of human brain functional networks and handedness and brain size remain unclear. Twenty-one left-handed and 32 right-handed healthy subjects underwent a resting-state functional magnetic resonance imaging scan. The whole brain functional networks were constructed by thresholding Pearson correlation matrices of 90 cortical and subcortical regions. Graph theory-based methods were employed to further analyze their topological properties. As expected, all participants demonstrated small-world topology, suggesting a highly efficient topological structure. Furthermore, we found that smaller brains showed higher local efficiency, whereas larger brains showed higher global efficiency, reflecting a suitable efficiency balance between local specialization and global integration of brain functional activity. Compared with right-handers, significant alterations in nodal efficiency were revealed in left-handers, involving the anterior and median cingulate gyrus, middle temporal gyrus, angular gyrus, and amygdala. Our findings indicated that the functional network organization in the human brain was associated with handedness and brain size.

  18. Sonographic Visualization of the Rotator Cable in Patients With Symptomatic Full-Thickness Rotator Cuff Tears: Correlation With Tear Size, Muscular Fatty Infiltration and Atrophy, and Functional Outcome.

    Science.gov (United States)

    Bureau, Nathalie J; Blain-Paré, Etienne; Tétreault, Patrice; Rouleau, Dominique M; Hagemeister, Nicola

    2016-09-01

    To assess the prevalence of sonographic visualization of the rotator cable in patients with symptomatic full-thickness rotator cuff tears and asymptomatic controls and to correlate rotator cable visualization with tear size, muscular fatty infiltration and atrophy, and the functional outcome in the patients with rotator cuff tears. Fifty-seven patients with rotator cuff tears and 30 asymptomatic volunteers underwent shoulder sonography for prospective assessment of the rotator cable and rotator cuff tear and responded to 2 functional outcome questionnaires (shortened Disabilities of the Arm, Shoulder, and Hand [QuickDASH] and Constant). In the patients with rotator cuff tears, appropriate tests were used to correlate rotator cable visualization with the tear size, functional outcome, muscular fatty infiltration, and atrophy. The patients with rotator cuff tears included 25 women and 32 men (mean age,57 years; range, 39-67 years), and the volunteers included 13 women and 17 men (mean age, 56 years; range, 35-64 years). The rotator cable was identified in 77% (23 of 30) of controls and 23% (13 of 57) of patients with rotator cuff tears. In the patients, nonvisualization of the rotator cable correlated with larger tears (P tears than asymptomatic controls and was associated with a larger tear size and greater supraspinatus fatty infiltration and atrophy. Diligent assessment of the supraspinatus muscle should be done in patients with rotator cuff tears without a visible rotator cable, as the integrity of these anatomic structures may be interdependent.

  19. Ischemic preconditioning enhances integrity of coronary endothelial tight junctions

    International Nuclear Information System (INIS)

    Li, Zhao; Jin, Zhu-Qiu

    2012-01-01

    Highlights: ► Cardiac tight junctions are present between coronary endothelial cells. ► Ischemic preconditioning preserves the structural and functional integrity of tight junctions. ► Myocardial edema is prevented in hearts subjected to ischemic preconditioning. ► Ischemic preconditioning enhances translocation of ZO-2 from cytosol to cytoskeleton. -- Abstract: Ischemic preconditioning (IPC) is one of the most effective procedures known to protect hearts against ischemia/reperfusion (IR) injury. Tight junction (TJ) barriers occur between coronary endothelial cells. TJs provide barrier function to maintain the homeostasis of the inner environment of tissues. However, the effect of IPC on the structure and function of cardiac TJs remains unknown. We tested the hypothesis that myocardial IR injury ruptures the structure of TJs and impairs endothelial permeability whereas IPC preserves the structural and functional integrity of TJs in the blood–heart barrier. Langendorff hearts from C57BL/6J mice were prepared and perfused with Krebs–Henseleit buffer. Cardiac function, creatine kinase release, and myocardial edema were measured. Cardiac TJ function was evaluated by measuring Evans blue-conjugated albumin (EBA) content in the extravascular compartment of hearts. Expression and translocation of zonula occludens (ZO)-2 in IR and IPC hearts were detected with Western blot. A subset of hearts was processed for the observation of ultra-structure of cardiac TJs with transmission electron microscopy. There were clear TJs between coronary endothelial cells of mouse hearts. IR caused the collapse of TJs whereas IPC sustained the structure of TJs. IR increased extravascular EBA content in the heart and myocardial edema but decreased the expression of ZO-2 in the cytoskeleton. IPC maintained the structure of TJs. Cardiac EBA content and edema were reduced in IPC hearts. IPC enhanced the translocation of ZO-2 from cytosol to cytoskeleton. In conclusion, TJs occur in

  20. Poly-ε-caprolactone Coated and Functionalized Porous Titanium and Magnesium Implants for Enhancing Angiogenesis in Critically Sized Bone Defects.

    Science.gov (United States)

    Roland, Laura; Grau, Michael; Matena, Julia; Teske, Michael; Gieseke, Matthias; Kampmann, Andreas; Beyerbach, Martin; Murua Escobar, Hugo; Haferkamp, Heinz; Gellrich, Nils-Claudius; Nolte, Ingo

    2015-12-22

    For healing of critically sized bone defects, biocompatible and angiogenesis supporting implants are favorable. Murine osteoblasts showed equal proliferation behavior on the polymers poly-ε-caprolactone (PCL) and poly-(3-hydroxybutyrate)/poly-(4-hydroxybutyrate) (P(3HB)/P(4HB)). As vitality was significantly better for PCL, it was chosen as a suitable coating material for further experiments. Titanium implants with 600 µm pore size were evaluated and found to be a good implant material for bone, as primary osteoblasts showed a vitality and proliferation onto the implants comparable to well bottom (WB). Pure porous titanium implants and PCL coated porous titanium implants were compared using Live Cell Imaging (LCI) with Green fluorescent protein (GFP)-osteoblasts. Cell count and cell covered area did not differ between the implants after seven days. To improve ingrowth of blood vessels into porous implants, proangiogenic factors like Vascular Endothelial Growth Factor (VEGF) and High Mobility Group Box 1 (HMGB1) were incorporated into PCL coated, porous titanium and magnesium implants. An angiogenesis assay was performed to establish an in vitro method for evaluating the impact of metallic implants on angiogenesis to reduce and refine animal experiments in future. Incorporated concentrations of proangiogenic factors were probably too low, as they did not lead to any effect. Magnesium implants did not yield evaluable results, as they led to pH increase and subsequent cell death.

  1. Poly-ε-caprolactone Coated and Functionalized Porous Titanium and Magnesium Implants for Enhancing Angiogenesis in Critically Sized Bone Defects

    Directory of Open Access Journals (Sweden)

    Laura Roland

    2015-12-01

    Full Text Available For healing of critically sized bone defects, biocompatible and angiogenesis supporting implants are favorable. Murine osteoblasts showed equal proliferation behavior on the polymers poly-ε-caprolactone (PCL and poly-(3-hydroxybutyrate/poly-(4-hydroxybutyrate (P(3HB/P(4HB. As vitality was significantly better for PCL, it was chosen as a suitable coating material for further experiments. Titanium implants with 600 µm pore size were evaluated and found to be a good implant material for bone, as primary osteoblasts showed a vitality and proliferation onto the implants comparable to well bottom (WB. Pure porous titanium implants and PCL coated porous titanium implants were compared using Live Cell Imaging (LCI with Green fluorescent protein (GFP-osteoblasts. Cell count and cell covered area did not differ between the implants after seven days. To improve ingrowth of blood vessels into porous implants, proangiogenic factors like Vascular Endothelial Growth Factor (VEGF and High Mobility Group Box 1 (HMGB1 were incorporated into PCL coated, porous titanium and magnesium implants. An angiogenesis assay was performed to establish an in vitro method for evaluating the impact of metallic implants on angiogenesis to reduce and refine animal experiments in future. Incorporated concentrations of proangiogenic factors were probably too low, as they did not lead to any effect. Magnesium implants did not yield evaluable results, as they led to pH increase and subsequent cell death.

  2. Preliminary report on the statistical evaluation of sorption data: Sorption as a function of mineralogy, temperature, time, and particle size

    International Nuclear Information System (INIS)

    Beckman, R.; Thomas, K.; Crowe, B.

    1988-05-01

    This report studies the transport of radionuclides from a repository to the environment by dissolution of the stored solid-waste form and subsequent transport in water. The sorption process may retard this movement of radionuclides from the repository to the accessible environment. A measure of this retardation process is the sorption ratio, R/sub D/, where R/sub D/ = (activity in solid phase per unit mass of solid)(activity in solution per unit volume of solution). In this study, predictions of the R/sub D/ values for the elements barium, cerium, cesium, europium, and strontium are developed from linear regression techniques. An R/sub D/ value was obtained for numerous drill core samples. Additional data include the particle size of the rock, temperature condition during the experiment, concentration of the sorbing element, and length of the sorption experiment. Preliminary regression results based on these data show that the temperature and length of the experiment are the most significant factors influencing the R/sub D/ values. Particle size has a slight effect, and based on a small amount of data, it appears that concentration had no effect. The x-ray diffraction data are used to classify the samples by mineralogy, and regression techniques are used to develop estimates of the R/sub D/ values. Zeolite abundance of 10% or more with some addition of clay increases the sorption values significantly. 12 refs., 3 figs., 6 tabs

  3. Gap-junction-mediated communication in human periodontal ligament cells.

    Science.gov (United States)

    Kato, R; Ishihara, Y; Kawanabe, N; Sumiyoshi, K; Yoshikawa, Y; Nakamura, M; Imai, Y; Yanagita, T; Fukushima, H; Kamioka, H; Takano-Yamamoto, T; Yamashiro, T

    2013-07-01

    Periodontal tissue homeostasis depends on a complex cellular network that conveys cell-cell communication. Gap junctions (GJs), one of the intercellular communication systems, are found between adjacent human periodontal ligament (hPDL) cells; however, the functional GJ coupling between hPDL cells has not yet been elucidated. In this study, we investigated functional gap-junction-mediated intercellular communication in isolated primary hPDL cells. SEM images indicated that the cells were in contact with each other via dendritic processes, and also showed high anti-connexin43 (Cx43) immunoreactivity on these processes. Gap-junctional intercellular communication (GJIC) among hPDL cells was assessed by fluorescence recovery after a photobleaching (FRAP) analysis, which exhibited dye coupling between hPDL cells, and was remarkably down-regulated when the cells were treated with a GJ blocker. Additionally, we examined GJs under hypoxic stress. The fluorescence recovery and expression levels of Cx43 decreased time-dependently under the hypoxic condition. Exposure to GJ inhibitor or hypoxia increased RANKL expression, and decreased OPG expression. This study shows that GJIC is responsible for hPDL cells and that its activity is reduced under hypoxia. This is consistent with the possible role of hPDL cells in regulating the biochemical reactions in response to changes in the hypoxic environment.

  4. High-performance DC SQUIDs with submicrometer niobium Josephson junctions

    Energy Technology Data Exchange (ETDEWEB)

    de Waal, V.J.; Klapwijk, T.M.; van den Hamer, P.

    1983-11-01

    We report on the fabrication and performance of low-noise, all-niobium, thin-film planar dc SQUIDs with submicrometer Josephson junctions. The junctions are evaporated obliquely through a metal shadow evaporation mask, which is made using optical lithography with 0.5 ..mu..m tolerance. The Josephson junction barrier is formed by evaporating a thin silicon film and with a subsequent oxidation in a glow discharge. The junction parameters can be reproduced within a factor of two. Typical critical currents of the SQUIDs are about 3 ..mu..A and the resistances are about 100 ..cap omega... With SQUIDs having an inductance of 1 nH the voltage modulation is a least 60 ..mu..V. An intrinsic energy resolution of 4 x 10/sup -32/ J/Hz has been reached. The SQUIDs are coupled to wire-wound input coils or with thin-film input coils. The thin-film input coil consists of a niobium spiral of 20 turns on a separate substrate. In both cases the coil is glued onto a 2-nH SQUID with a coupling efficiency of at least 0.5. Referred to the thin-film input coil, the best coupled energy resolution achieved is 1.2 x 10/sup -30/ J/Hz measured in a flux-locked loop at frequencies above 10 Hz. As far as we know, this is the best figure achieved with an all-refractory-metal thin-film SQUID. The fabrication technique used is suited for making circuits with SQUID and pickup coil on the same substrate. We describe a compact, planar, first-order gradiometer integrated with a SQUID on a single substrate. The gradient noise of this device is 3 x 10/sup -12/ Tm/sup -1/. The gradiometer has a size of 12 mm x 17 mm, is simple to fabricate, an is suitable for biomedical applications.

  5. High-performance dc SQUIDs with submicrometer niobium Josephson junctions

    Science.gov (United States)

    de Waal, V. J.; Klapwijk, T. M.; van den Hamer, P.

    1983-11-01

    We report on the fabrication and performance of low-noise, all-niobium, thin-film planar dc SQUIDs with submicrometer Josephson junctions. The junctions are evaporated obliquely through a metal shadow evaporation mask, which is made using optical lithography with 0.5 µm tolerance. The Josephson junction barrier is formed by evaporating a thin silicon film and with a subsequent oxidation in a glow discharge. The junction parameters can be reproduced within a factor of two. Typical critical currents of the SQUIDs are about 3 µA and the resistances are about 100 Ω. With SQUIDs having an inductance of 1 nH the voltage modulation is at least 60 µV. An intrinsic energy resolution of 4×10-32 J/Hz has been reached. The SQUIDs are coupled to wire-wound input coils or with thin-film input coils. The thin-film input coil consists of a niobium spiral of 20 turns on a separate substrate. In both cases the coil is glued onto a 2-nH SQUID with a coupling efficiency of at least 0.5. Referred to the thin-film input coil, the best coupled energy resolution achieved is 1.2×10-30 J/Hz measured in a flux-locked loop at frequencies above 10 Hz. As far as we know, this is the best figure achieved with an all-refractory-metal thin-film SQUID. The fabrication technique used is suited for making circuits with SQUID and pickup coil on the same substrate. We describe a compact, planar, first-order gradiometer integrated with a SQUID on a single substrate. The gradient noise of this device is 3×10-12 T m-1. The gradiometer has a size of 12 mm×17 mm, is simple to fabricate, and is suitable for biomedical applications.

  6. Electron optics with ballistic graphene junctions

    Science.gov (United States)

    Chen, Shaowen

    Electrons transmitted across a ballistic semiconductor junction undergo refraction, analogous to light rays across an optical boundary. A pn junction theoretically provides the equivalent of a negative index medium, enabling novel electron optics such as negative refraction and perfect (Veselago) lensing. In graphene, the linear dispersion and zero-gap bandstructure admit highly transparent pn junctions by simple electrostatic gating, which cannot be achieved in conventional semiconductors. Robust demonstration of these effects, however, has not been forthcoming. Here we employ transverse magnetic focusing to probe propagation across an electrostatically defined graphene junction. We find perfect agreement with the predicted Snell's law for electrons, including observation of both positive and negative refraction. Resonant transmission across the pn junction provides a direct measurement of the angle dependent transmission coefficient, and we demonstrate good agreement with theory. Comparing experimental data with simulation reveals the crucial role played by the effective junction width, providing guidance for future device design. Efforts toward sharper pn junction and possibility of zero field Veselago lensing will also be discussed. This work is supported by the Semiconductor Research Corporations NRI Center for Institute for Nanoelectronics Discovery and Exploration (INDEX).

  7. Eight-logic memory cell based on multiferroic junctions

    International Nuclear Information System (INIS)

    Yang Feng; Zhou, Y C; Tang, M H; Liu Fen; Ma Ying; Zheng, X J; Zhao, W F; Xu, H Y; Sun, Z H

    2009-01-01

    A model is proposed for a device combining a multiferroic tunnel junction with a magnetoelectric (ME) film in which the magnetic configuration is controlled by the electric field. Calculations embodying the Green's function approach show that the magnetic polarization can be switched on and off by an electric field in the ME film due to the effect of elastic coupling interaction. Using a model including the spin-filter effect and screening of polarization charges, we have produced eight logic states of tunnelling resistance in the tunnel junction and have obtained corresponding laws that control them. The results provide some insights into the realization of an eight-logic memory cell. (fast track communication)

  8. Sound over Matter: The Effects of Functional Noise, Robot Size and Approach Velocity in Human-Robot Encounters

    NARCIS (Netherlands)

    Joosse, M.P.; Lohse, M.; Evers, Vanessa

    2014-01-01

    In our previous work we introduced functional noise as a modality for robots to communicate intent [6]. In this follow-up experiment, we replicated the first study with a robot which was taller in order to find out if the same results would apply to a tall vs. a short robot. Our results show a

  9. Phase Sensitive Measurements of Ferromagnetic Josephson Junctions for Cryogenic Memory Applications

    Science.gov (United States)

    Niedzielski, Bethany Maria

    A Josephson junction is made up of two superconducting layers separated by a barrier. The original Josephson junctions, studied in the early 1960's, contained an insulating barrier. Soon thereafter, junctions with normal-metal barriers were also studied. Ferromagnetic materials were not even theoretically considered as a barrier layer until around 1980, due to the competing order between ferromagnetic and superconducting systems. However, many exciting physical phenomena arise in hybrid superconductor/ferromagnetic devices, including devices where the ground state phase difference between the two superconductors is shifted by pi. Since their experimental debut in 2001, so-called pi junctions have been demonstrated by many groups, including my own, in systems with a single ferromagnetic layer. In this type of system, the phase of the junction can be set to either 0 or pi depending on the thickness of the ferromagnetic layer. Of interest, however, is the ability to control the phase of a single junction between the 0 and pi states. This was theoretically shown to be possible in a system containing two ferromagnetic layers (spin-valve junctions). If the materials and their thicknesses are properly chosen to manipulate the electron pair correlation function, then the phase state of a spin-valve Josephson junction should be capable of switching between the 0 and ? phase states when the magnetization directions of the two ferromagnetic layers are oriented in the antiparallel and parallel configurations, respectively. Such a phase-controllable junction would have immediate applications in cryogenic memory, which is a necessary component to an ultra-low power superconducting computer. A fully superconducting computer is estimated to be orders of magnitude more energy-efficient than current semiconductor-based supercomputers. The goal of this work was to experimentally verify this prediction for a phase-controllable ferromagnetic Josephson junction. To address this

  10. DHT deficiency perturbs the integrity of the rat seminiferous epithelium by disrupting tight and adherens junctions.

    Science.gov (United States)

    Kolasa, Agnieszka; Marchlewicz, Mariola; Wenda-Różewicka, Lidia; Wiszniewska, Barbara

    2011-01-01

    In rats with a DHT deficiency induced by finasteride, morphological changes in the seminiferous epithelium were observed. The structural alterations were manifested by the premature germ cells sloughing into the lumen of seminiferous tubules. The etiology of this disorder could be connected with intercellular junctions disintegration. We showed in the immunohistochemical study the changes in expression of some proteins building tight and adherens junctions. The depression of N-cadherin, β-catenin and occludin immunoexpressions could be the reason for the release of immature germ cells from the seminiferous epithelium. However, the observed increase of the immunohistochemical reaction intensity of vinculin, one of the cadherin/catenin complex regulators, could be insufficient to maintain the proper function of adherens junctions. The hormonal imbalance appears to influence the pattern of expression of junctional proteins in the seminiferous epithelium. It could lead to untimely germ cells sloughing, and ultimately could impair fertility.

  11. Gas selectivity of SILAR grown CdS nano-bulk junction

    Science.gov (United States)

    Jayakrishnan, R.; Nair, Varun G.; Anand, Akhil M.; Venugopal, Meera

    2018-03-01

    Nano-particles of cadmium sulphide were deposited on cleaned copper substrate by an automated sequential ionic layer adsorption reaction (SILAR) system. The grown nano-bulk junction exhibits Schottky diode behavior. The response of the nano-bulk junction was investigated under oxygen and hydrogen atmospheric conditions. The gas response ratio was found to be 198% for Oxygen and 34% for Hydrogen at room temperature. An increase in the operating temperature of the nano-bulk junction resulted in a decrease in their gas response ratio. A logarithmic dependence on the oxygen partial pressure to the junction response was observed, indicating a Temkin isothermal behavior. Work function measurements using a Kelvin probe demonstrate that the exposure to an oxygen atmosphere fails to effectively separate the charges due to the built-in electric field at the interface. Based on the benefits like simple structure, ease of fabrication and response ratio the studied device is a promising candidate for gas detection applications.

  12. Hydration effect on the electronic transport properties of oligomeric phenylene ethynylene molecular junctions

    International Nuclear Information System (INIS)

    Zong-Liang, Li; Huai-Zhi, Li; Yong, Ma; Guang-Ping, Zhang; Chuan-Kui, Wang

    2010-01-01

    A first-principles computational method based on the hybrid density functional theory is developed to simulate the electronic transport properties of oligomeric phenylene ethynylene molecular junctions with H 2 O molecules accumulated in the vicinity as recently reported by Na et al. [Nanotechnology 18 424001 (2007)]. The numerical results show that the hydrogen bonds between the oxygen atoms of the oligomeric phenylene ethynylene molecule and H 2 O molecules result in the localisation of the molecular orbitals and lead to the lower transition peaks. The H 2 O molecular chains accumulated in the vicinity of the molecular junction can not only change the electronic structure of the molecular junctions, but also open additional electronic transport pathways. The obvious influence of H 2 O molecules on the electronic structure of the molecular junction and its electronic transport properties is thus demonstrated. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  13. Charge and spin current oscillations in a tunnel junction induced by magnetic field pulses

    Energy Technology Data Exchange (ETDEWEB)

    Dartora, C.A., E-mail: cadartora@eletrica.ufpr.br [Electrical Engineering Department, Federal University of Parana (UFPR), C.P. 19011 Curitiba, 81.531-970 PR (Brazil); Nobrega, K.Z., E-mail: bzuza1@yahoo.com.br [Federal Institute of Education, Science and Technolgy of Maranhão (IFMA), Av. Marechal Castelo Branco, 789, São Luís, 65.076-091 MA (Brazil); Cabrera, G.G., E-mail: cabrera@ifi.unicamp.br [Instituto de Física ‘Gleb Wataghin’, Universidade Estadual de Campinas (UNICAMP), C.P. 6165, Campinas 13.083-970 SP (Brazil)

    2016-08-15

    Usually, charge and spin transport properties in tunnel junctions are studied in the DC bias regime and/or in the adiabatic regime of time-varying magnetic fields. In this letter, the temporal dynamics of charge and spin currents in a tunnel junction induced by pulsed magnetic fields is considered. At low bias voltages, energy and momentum of the conduction electrons are nearly conserved in the tunneling process, leading to the description of the junction as a spin-1/2 fermionic system coupled to time-varying magnetic fields. Under the influence of pulsed magnetic fields, charge and spin current can flow across the tunnel junction, displaying oscillatory behavior, even in the absence of DC bias voltage. A type of spin capacitance function, in close analogy to electric capacitance, is predicted.

  14. Device characterization for design optimization of 4 junction inverted metamorphic concentrator solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Geisz, John F.; France, Ryan M.; Steiner, Myles A.; Friedman, Daniel J. [National Renewable Energy Laboratory, Golden, CO 80401 (United States); García, Iván [National Renewable Energy Laboratory, Golden, CO 80401 USA and Instituto de Energía Solar, Universidad Politécnica de Madrid, Avda Complutense s/n, 28040 Madrid (Spain)

    2014-09-26

    Quantitative electroluminescence (EL) and luminescent coupling (LC) analysis, along with more conventional characterization techniques, are combined to completely characterize the subcell JV curves within a fourjunction (4J) inverted metamorphic solar cell (IMM). The 4J performance under arbitrary spectral conditions can be predicted from these subcell JV curves. The internal radiative efficiency (IRE) of each junction has been determined as a function of current density from the external radiative efficiency using optical modeling, but this required the accurate determination of the individual junction current densities during the EL measurement as affected by LC. These measurement and analysis techniques can be applied to any multijunction solar cell. The 4J IMM solar cell used to illustrate these techniques showed excellent junction quality as exhibited by high IRE and a one-sun AM1.5D efficiency of 36.3%. This device operates up to 1000 suns without limitations due to any of the three tunnel junctions.

  15. [Inhibition of gap junctional intercellular communication protects astrocytes from hypoxia/reoxygenation injury].

    Science.gov (United States)

    Tong, Xu-Hui; Gu, Yu-Chen; Jiao, Hao; Yu, Li; Dong, Shu-Ying

    2015-01-01

    To investigate the effects of inhibiting gap junctional intercellular communication on hypoxia/reoxygenation injury in astrocytes. Primary cultured cerebral cortical astrocytes of neonate rats were divided into normal control group, hypoxia reoxygenation injury group and 18-α-glycyrrhetinic acid and oleamide (gap junctional intercellular channel inhibitors) group. The gap junction intercellular communication was determined by Parachute assay. The viability of astrocyes was detected by MTT assay. The apoptosis of astrocytes were detected with annexin V/PI and Hoechst 33258 staining. Compared with the normal control group, the gap junctional function of astrocytes was increased significantly in ischemia/reperfusion group (Pastrocytes decreased significantly (Pastrocytes in18-α-glycyrrhetinic acid and oleamide group decreased significantly (Pastrocytes increased significantly (Pastrocytes.

  16. Structure and signaling at hydroid polyp-stolon junctions, revisited

    Directory of Open Access Journals (Sweden)

    Katherine L. Harmata

    2015-09-01

    Full Text Available The gastrovascular system of colonial hydroids is central to homeostasis, yet its functional biology remains poorly understood. A probe (2′,7′-dichlorodihydrofluorescein diacetate for reactive oxygen species (ROS identified fluorescent objects at polyp-stolon junctions that emit high levels of ROS. A nuclear probe (Hoechst 33342 does not co-localize with these objects, while a mitochondrial probe (rhodamine 123 does. We interpret these objects as mitochondrion-rich cells. Confocal microscopy showed that this fluorescence is situated in large columnar cells. Treatment with an uncoupler (2,4-dinitrophenol diminished the ROS levels of these cells relative to background fluorescence, as did removing the stolons connecting to a polyp-stolon junction. These observations support the hypothesis that the ROS emanate from mitochondrion-rich cells, which function by pulling open a valve at the base of the polyp. The open valve allows gastrovascular fluid from the polyp to enter the stolons and vice versa. The uncoupler shifts the mitochondrial redox state in the direction of oxidation, lowering ROS levels. By removing the stolons, the valve is not pulled open, metabolic demand is lowered, and the mitochondrion-rich cells slowly regress. Transmission electron microscopy identified mitochondrion-rich cells adjacent to a thick layer of mesoglea at polyp-stolon junctions. The myonemes of these myoepithelial cells extend from the thickened mesoglea to the rigid perisarc on the outside of the colony. The perisarc thus anchors the myoepithelial cells and allows them to pull against the mesoglea and open the lumen of the polyp-stolon junction, while relaxation of these cells closes the lumen.

  17. Shot noise in YBCO bicrystal Josephson junctions

    DEFF Research Database (Denmark)

    Constantinian, K.Y.; Ovsyannikov, G.A.; Borisenko, I.V.

    2003-01-01

    We measured spectral noise density in YBCO symmetric bicrystal Josephson junctions on sapphire substrates at bias voltages up to 100 mV and T 4.2 K. Normal state resistance of the Josephson junctions, R-N = 20-90 Omega and ICRN up to 2.2 mV have been observed in the experimental samples. Noise...... may explain the experimentally measured linewidth broadening of Josephson oscillations at mm and submm wave frequencies in high-Tc superconducting junctions. Experimental results are discussed in terms of bound states existing at surfaces of d-wave superconducting electrodes....

  18. delta-biased Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Monaco, R.; Mygind, Jesper; Koshelet, V.

    2010-01-01

    Abstract: The behavior of a long Josephson tunnel junction drastically depends on the distribution of the dc bias current. We investigate the case in which the bias current is fed in the central point of a one-dimensional junction. Such junction configuration has been recently used to detect...... the persistent currents circulating in a superconducting loop. Analytical and numerical results indicate that the presence of fractional vortices leads to remarkable differences from the conventional case of uniformly distributed dc bias current. The theoretical findings are supported by detailed measurements...

  19. Parametric frequency conversion in long Josephson junctions

    International Nuclear Information System (INIS)

    Irie, F.; Ashihara, S.; Yoshida, K.

    1976-01-01

    Current steps at voltages corresponding to the parametric coupling between an applied r.f. field and junction resonant modes have been observed in long Josephson tunnel junctions in the flux-flow state. The observed periodic variations of the step height due to the applied magnetic field are explained quantitatively by a perturbational analysis using Josephson phase equations. The present study demonstrates that the moving vortex array can serve as a coherent pump wave for signal waves propagating in the barrier region, which indicates, as a result, the possibility of traveling-wave parametric devices with long Josephson tunnel junctions. (author)

  20. The Ly6 protein coiled is required for septate junction and blood brain barrier organisation in Drosophila.

    Directory of Open Access Journals (Sweden)

    Assia Hijazi

    Full Text Available BACKGROUND: Genetic analysis of the Drosophila septate junctions has greatly contributed to our understanding of the mechanisms controlling the assembly of these adhesion structures, which bear strong similarities with the vertebrate tight junctions and the paranodal septate junctions. These adhesion complexes share conserved molecular components and have a common function: the formation of paracellular barriers restraining the diffusion of solutes through epithelial and glial envelopes. METHODOLOGY/PRINCIPAL FINDINGS: In this work we characterise the function of the Drosophila cold gene, that codes for a protein belonging to the Ly6 superfamily of extracellular ligands. Analysis of cold mutants shows that this gene is specifically required for the organisation of the septate junctions in epithelial tissues and in the nervous system, where its contribution is essential for the maintenance of the blood-brain barrier. We show that cold acts in a cell autonomous way, and we present evidence indicating that this protein could act as a septate junction component. CONCLUSION/SIGNIFICANCE: We discuss the specific roles of cold and three other Drosophila members of the Ly6 superfamily that have been shown to participate in a non-redundant way in the process of septate junction assembly. We propose that vertebrate Ly6 proteins could fulfill analogous roles in tight junctions and/or paranodal septate junctions.