bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Control of Movement Following Traumatic Brain Injury
Authors: Kozlowski Dorothy A. , Leasure J. Leigh , Schallert Timothy 
Published: December 2012

AbstractTraumatic brain injury (TBI) results in a variety of impairments in cognition, mood, sensation, and movement, depending upon the location and severity of injury. Although not as extensively studied as cognitive impairments, motor impairments are common, especially in moderately to severely injured patients. The recovery of these deficits is not usually complete; however, extensive effort is put into the rehabilitation of motor skills to enhance independence and quality of life. Understanding the motor recovery process and how it can be influenced by rehabilitation has been extensively studied in animal models of stroke and focal lesions, albeit to a lesser extent following animal models of TBI. Injury‐induced neural plasticity is intricately involved in motor recovery and influenced by behavioral compensation and rehabilitation following stroke and focal lesions. New studies in animal models of TBI indicate that neural plasticity and the processes of motor recovery and rehabilitation following brain injury may not mirror those processes shown to occur following stroke. Further examination of motor recovery, rehabilitation, and plasticity in animal models of TBI as well as in individuals with TBI will be necessary to fully understand the control of movement following brain injury. © 2013 American Physiological Society.Compr Physiol3:121‐139, 2013.
Central Sleep Apnea
Authors: Javaheri S. , Dempsey J.A. 
Published: December 2012

AbstractNeurophysiologically, central apnea is due to a temporary failure in the pontomedullary pacemaker generating breathing rhythm. As a polysomnographic finding, central apneas occur in many pathophysiological conditions. Depending on the cause or mechanism, central apneas may not be clinically significant, for example, those that occur normally at sleep onset. In contrast, central apneas occur in a number of disorders and result in pathophysiological consequences. Central apneas occur commonly in high‐altitude sojourn, disrupt sleep, and cause desaturation. Central sleep apnea also occurs in number of disorders across all age groups and both genders. Common causes of central sleep apnea in adults are congestive heart failure and chronic use of opioids to treat pain. Under such circumstances, diagnosis and treatment of central sleep apnea may improve quality of life, morbidity, and perhaps mortality. The mechanisms of central sleep apnea have been best studied in congestive heart failure and hypoxic conditions when there is increased CO2sensitivity below eupnea resulting in lowering eupneic PCO2below apneic threshold causing cessation of breathing until the PCO2rises above the apneic threshold when breathing resumes. In many other disorders, the mechanism of central sleep apnea (CSA) remains to be investigated. © 2013 American Physiological Society.Compr Physiol3:141‐163, 2013.
How Animals Move: Comparative Lessons on Animal Locomotion
Authors: Schaeffer Paul J. , Lindstedt Stan L. 
Published: December 2012

AbstractComparative physiology often provides unique insights in animal structure and function. It is specifically through this lens that we discuss the fundamental properties of skeletal muscle and animal locomotion, incorporating variation in body size and evolved difference among species. For example, muscle frequenciesin vivoare highly constrained by body size, which apparently tunes muscle use to maximize recovery of elastic recoil potential energy. Secondary to this constraint, there is an expected linking of skeletal muscle structural and functional properties. Muscle is relatively simple structurally, but by changing proportions of the few muscle components, a diverse range of functional outputs is possible. Thus, there is a consistent and predictable relation between muscle function and myocyte composition that illuminates animal locomotion. When animals move, the mechanical properties of muscle diverge from the static textbook force‐velocity relations described by A. V. Hill, as recovery of elastic potential energy together with force and power enhancement with activation during stretch combine to modulate performance. These relations are best understood through the tool of work loops. Also, when animals move, locomotion is often conveniently categorized energetically. Burst locomotion is typified by high‐power outputs and short durations while sustained, cyclic, locomotion engages a smaller fraction of the muscle tissue, yielding lower force and power. However, closer examination reveals that rather than a dichotomy, energetics of locomotion is a continuum. There is a remarkably predictable relationship between duration of activity and peak sustainable performance. © 2013 American Physiological Society.Compr Physiol3:289‐314, 2013.
Porphyrin and Heme Metabolism and the Porphyrias
Authors: Bonkovsky Herbert L. , Guo Jun‐Tao , Hou Weihong , Li Ting , Narang Tarun , Thapar Manish 
Published: December 2012

AbstractPorphyrins and metalloporphyrins are the key pigments of life on earth as we know it, because they include chlorophyll (a magnesium‐containing metalloporphyrin) and heme (iron protoporphyrin). In eukaryotes, porphyrins and heme are synthesized by a multistep pathway that involves eight enzymes. The first and rate‐controlling step is the formation of delta‐aminolevulinic acid (ALA) from glycine plus succinyl CoA, catalyzed by ALA synthase. Intermediate steps occur in the cytoplasm, with formation of the monopyrrole porphobilinogen and the tetrapyrroles hydroxymethylbilane and a series of porphyrinogens, which are serially decarboxylated. Heme is utilized chiefly for the formation of hemoglobin in erythrocytes, myoglobin in muscle cells, cytochromes P‐450 and mitochondrial cytochromes, and other hemoproteins in hepatocytes. The rate‐controlling step of heme breakdown is catalyzed by heme oxygenase (HMOX), of which there are two isoforms, called HMOX1 and HMOX2. HMOX breaks down heme to form biliverdin, carbon monoxide, and iron. The porphyrias are a group of disorders, mainly inherited, in which there are defects in normal porphyrin and heme synthesis. The cardinal clinical features are cutaneous (due to the skin‐damaging effects of excess deposited porphyrins) or neurovisceral attacks of pain, sometimes with weakness, delirium, seizures, and the like (probably due mainly to neurotoxic effects of ALA). The treatment of choice for the acute hepatic porphyrias is intravenous heme therapy, which repletes a critical regulatory heme pool in hepatocytes and leads to downregulation of hepatic ALA synthase, which is a biochemical hallmark of all forms of acute porphyria in relapse. © 2013 American Physiological Society.Compr Physiol3:365‐401, 2013.
Hepatocyte Polarity
Authors: Treyer Aleksandr , Müsch Anne 
Published: December 2012

AbstractHepatocytes, like other epithelia, are situated at the interface between the organism's exterior and the underlying internal milieu and organize the vectorial exchange of macromolecules between these two spaces. To mediate this function, epithelial cells, including hepatocytes, are polarized with distinct luminal domains that are separated by tight junctions from lateral domains engaged in cell‐cell adhesion and from basal domains that interact with the underlying extracellular matrix. Despite these universal principles, hepatocytes distinguish themselves from other nonstriated epithelia by their multipolar organization. Each hepatocyte participates in multiple, narrow lumina, the bile canaliculi, and has multiple basal surfaces that face the endothelial lining. Hepatocytes also differ in the mechanism of luminal protein trafficking from other epithelia studied. They lack polarized protein secretion to the luminal domain and target single‐spanning and glycosylphosphatidylinositol‐anchored bile canalicular membrane proteins via transcytosis from the basolateral domain. We compare this unique hepatic polarity phenotype with that of the more common columnar epithelial organization and review our current knowledge of the signaling mechanisms and the organization of polarized protein trafficking that govern the establishment and maintenance of hepatic polarity. The serine/threonine kinase LKB1, which is activated by the bile acid taurocholate and, in turn, activates adenosine monophosphate kinase‐related kinases including AMPK1/2 and Par1 paralogues has emerged as a key determinant of hepatic polarity. We propose that the absence of a hepatocyte basal lamina and differences in cell‐cell adhesion signaling that determine the positioning of tight junctions are two crucial determinants for the distinct hepatic and columnar polarity phenotypes. © 2013 American Physiological Society.Compr Physiol3:243‐287, 2013.
Renal Ammonia Metabolism and Transport
Authors: Weiner I. David , Verlander Jill W. 
Published: December 2012

AbstractRenal ammonia metabolism and transport mediates a central role in acid‐base homeostasis. In contrast to most renal solutes, the majority of renal ammonia excretion derives from intrarenal production, not from glomerular filtration. Renal ammoniagenesis predominantly results from glutamine metabolism, which produces 2 NH4+and 2 HCO3−for each glutamine metabolized. The proximal tubule is the primary site for ammoniagenesis, but there is evidence for ammoniagenesis by most renal epithelial cells. Ammonia produced in the kidney is either excreted into the urine or returned to the systemic circulation through the renal veins. Ammonia excreted in the urine promotes acid excretion; ammonia returned to the systemic circulation is metabolized in the liver in a HCO3−‐consuming process, resulting in no net benefit to acid‐base homeostasis. Highly regulated ammonia transport by renal epithelial cells determines the proportion of ammonia excreted in the urine versus returned to the systemic circulation. The traditional paradigm of ammonia transport involving passive NH3diffusion, protonation in the lumen and NH4+trapping due to an inability to cross plasma membranes is being replaced by the recognition of limited plasma membrane NH3permeability in combination with the presence of specific NH3‐transporting and NH4+‐transporting proteins in specific renal epithelial cells. Ammonia production and transport are regulated by a variety of factors, including extracellular pH and K+, and by several hormones, such as mineralocorticoids, glucocorticoids and angiotensin II. This coordinated process of regulated ammonia production and transport is critical for the effective maintenance of acid‐base homeostasis. © 2013 American Physiological Society.Compr Physiol3:201‐220, 2013.
Physiology of Cholangiocytes
Authors: Tabibian James H. , Masyuk Anatoliy I. , Masyuk Tetyana V. , O'Hara Steven P. , LaRusso Nicholas F. 
Published: December 2012

AbstractCholangiocytes are epithelial cells that line the intra‐ and extrahepatic ducts of the biliary tree. The main physiologic function of cholangiocytes is modification of hepatocyte‐derived bile, an intricate process regulated by hormones, peptides, nucleotides, neurotransmitters, and other molecules through intracellular signaling pathways and cascades. The mechanisms and regulation of bile modification are reviewed herein. © 2013 American Physiological Society.Compr Physiol3:541‐565, 2013.
Sustainable Development in Iran: An Exploratory Study of University Students' Attitudes and Knowledge about Sustainable Developmenta
Authors: Bahaee Mahmood , Perez‐Batres Luis A. , Pisani Michael J. , Miller Van V. , Saremi Mahmoud 
Published: December 2012

ABSTRACTIn this paper, we explore the perceptions of Iranian undergraduate college students of the concept of sustainable development (SD). In so doing, we measure students' attitudes and knowledge on the various aspects of the SD paradigm. The results indicate that while most Iranian students surveyed have a positive perception of SD, their attitudes and knowledge about it is linked to certain demographic characteristics. For example, Iranian female college students are more knowledgeable about SD than their male Iranian counterparts. Implications of these findings are further explored. Copyright © 2012 John Wiley & Sons, Ltd and ERP Environment.
Corporate Supply Chain Responsibility: Drivers and Barriers for Sustainable Food Retailing
Authors: Chkanikova Olga , Mont Oksana 
Published: December 2012

ABSTRACTThe paper aims to provide a systematic overview of the drivers and barriers for food retailers to implement corporate supply chain responsibility. The research is based on a literature analysis and semi‐structured interviews with food retailers, with primary focus on Swedish conventional supermarket chains. The paper contributes to the existing body of research by providing the food retailers’ own perspective on the factors that trigger addressing sustainability concerns in their supply chain and by providing a taxonomy of drivers and barriers. As a result, a number of additional factors that influence the launch of responsible supply chain practices have been identified. Interestingly some of these factors are beyond the trivial driver‐barrier dichotomy. This paper is of interest to food retailers who aim to design sustainable supply chain strategies and justify associated investments, and for policymakers who aim to support retailers in their transition towards sustainable practices. Copyright © 2012 John Wiley & Sons, Ltd and ERP Environment.
Synthesis of Aminotetrazolyl Esters from Cyanogen Azide with Amino Esters
Authors: Joo Young‐Hyuk , Cho Soo Gyeong , Goh Eun Mee , Parrish Damon A. , Shreeve Jean'ne M. 
Published: December 2012

AbstractSeveral α‐amino esters (and their hydrochloride salts) were treated with cyanogen azide at ambient temperature in a mixture of water and acetonitrile to form chiral 5‐aminotetrazole derivatives in good yields (47–69 %). The cyanogen azide was prepared from cyanogen bromide and sodium azide. Other functionalized α‐amino esters (cysteine, arginine, histidine, and serine) were formed in only trace amounts and were difficult to purify by column chromatography. All 5‐aminotetrazoles (i.e., 1–8) were characterized by IR spectroscopy, 1H, 13C, and 15N NMR spectroscopy, and elemental analysis. The structures of 3–7 were obtained by single‐crystal X‐ray structure analysis.
A stencil adaptive phase‐field lattice Boltzmann method for two dimensional incompressible multiphase flows
Authors: Shao J. Y. , Shu C. , Wu J. , Chew Y. T. 
Published: December 2012

SUMMARYThis paper presents a stencil adaptive phase‐field lattice Boltzmann method (LBM) for the simulation of two‐dimensional multiphase flows. In the phase‐field model, the interface is viewed as a layer with finite thickness where physical parameters vary steeply and continuously. In the present study, a phase‐field LBM is used. In this model, the Cahn–Hilliard equation can be correctly recovered by LBM without additional terms. The phase‐field LBM can easily resolve topology change and large deformation of an interface. The major challenge faced by the phase‐field model is to approach sharp interface limit within affordable computational loads. A natural solution is to supplement the phase‐field model with the adaptive mesh refinement technique. In fact, much effort has been devoted to alleviate this issue with regards to Navier–Stokes solvers. However, in the realm of LBM, few works can be found in the literature. The present work is the first endeavour to incorporate the stencil adaptive technique into the phase‐field LBM. The proposed method enables high resolution of interface with considerable savings in grid points. In addition, owing to the symmetric structure of two stencils used, the present adaptive phase‐field LBM is freed from complicated spatial and temporal interpolation and modification of the collision term. First, the accuracy, efficiency and convergence of this method are testified through the simulation of a stationary bubble. Furthermore, its ability to probe several types of interfacial dynamics including bubbly flows and contact line problems has also been demonstrated. Copyright © 2012 John Wiley & Sons, Ltd.
On the Catalytic Degradation in Fuel Cell Power Supplies for Long‐Life Mobile Field Sensors
Authors: Thangavelautham J. , Dubowsky S. 
Published: December 2012

AbstractImportant tasks such as environment monitoring require field devices such as sensors that can operate for long durations. Current power supply technologies such as batteries limit many applications. Fuel cells are a promising alternative to batteries because they can have much higher energy densities. However, their lives may be short due to catalyst degradation. Here, a simplified model of proton exchange membrane (PEM) fuel cell catalyst degradation is applied to small fuel cells. The model focuses on the combined effects of catalyst dissolution and migration. The effect of migration on catalyst degradation is found to be substantial and this has not been accounted for in previous models. The model considers the effect of field conditions such as varying power demands, temperature and humidity, and predicts the catalyst life of the fuel cell and its power output. The predicted life is a proposed metric that can quantify the relative importance and effect of field conditions on the catalyst particularly for the design and control of fuel cell power supplies. Experiments are presented that support the model. This model is applied to a study on field sensors and results suggests unless PEM fuel cells are isolated from damaging field conditions, they will have short lives.
Optimization of a High Temperature PEMFC micro‐CHP System by Formulation and Application of a Process Integration Methodology
Authors: Arsalis A. , Nielsen M. P. , Kær S. K. 
Published: December 2012

AbstractA 1 kWe micro combined heat and power (CHP) system based on high temperature proton exchange membrane fuel cell (PEMFC) technology is modeled and optimized by formulation and application of a process integration methodology. The system can provide heat and electricity for a single‐family household. It consists of a fuel cell stack, a fuel processing subsystem, heat exchangers, and balance‐of‐plant components. The optimization methodology involves system optimization attempting to maximize the net electrical efficiency, and then by use of a mixed integer nonlinear programming (MINLP) problem formulation, the heat exchange network (HEN) annual cost is minimized. The results show the high potential of the proposed model since high efficiencies are accomplished. The net electrical efficiency and total system efficiency, based on lower heating value (LHV), are 35.2% and 91.1%, respectively. The minimized total annual cost of the HEN is $8,147 year–1.
Experimental Study of an SOFC Stack Operated With Autothermally Reformed Diesel Fuel
Authors: Rautanen M. , Halinen M. , Noponen M. , Koskela K. , Vesala H. , Kiviaho J. 
Published: December 2012

AbstractA 500 W SOFC stack provided by Topsoe Fuel Cells A/S was run with reformed diesel fuel for 1,200 h. Diesel fuel used was Swedish Environmental Class 1 containing <10 ppm of sulfur. The fuel was reformed with an autothermal reformer (ATR). The reformer consisted of a mixing chamber and a reactor chamber containing a noble metal catalyst provided by SüdChemie. The reformer used the diesel fuel without any pre‐treatment such as sulfur adsorbent. The reformer unit was able to achieve high conversion of reactants with only ppm levels of higher hydrocarbons at the reformer outlet. Particulate emissions of the reformer were measured to be 30 μg m–3, a very low value even below daily exposure limits in ambient air set by the European Comission directives. The stack was first run with 3% humidified H2 + N2 fuel to obtain baseline performance and then switched to reformate. Diesel reformate was found not to induce significantly more long‐term degradation on the stack compared to hydrogen case. However, an initial degradation of about 20 mV cell–1 was observed during the first 150 h on diesel fuel reformate. This could be an indication of a poisoning mechanism taking place, but needs further research to be verified.
Thermo‐Mechanical Response of Fuel Cell Electrodes: Constitutive Model and Application in Studying the Structural Response of Polymer Electrolyte Fuel Cell
Authors: Poornesh K. K. , Xiao Y. , Cho C. 
Published: December 2012

AbstractThe characterization of the mechanical properties of fuel cell electrodes through the experimental techniques is a complex task due to the low thickness, constituents' heterogeneous composition, and fragile nature of the film. We present a preliminary investigation on the thermomechanical response of fuel cell catalyst layer (CL) obtained through the numerical experiment. Since the Nafion ionomer is one of the constituents' of the CL, a modified micromechanically motivated viscoplastic model is adopted to characterize the Nafion ionomer in terms of reduced density factor to account for the void content. The catalyst agglomerates are taken as inclusions in the ionomer matrix to form a composite unit which is used to plot the true stress–true strain response. Practicality of this work is tested by implementing the electrode layer as a separate component in the single fuel cell unit cell model. A remarkable difference in the magnitude of stress levels in the membrane is observed under thermal and hydrated conditions with the presence and absence of electrode layer in the simulation domain. The present work will assist in improved understanding of the localized stress distribution in the membrane, which is essential to understand its mechanical endurance.
Amyloid beta accumulation in HIV‐1‐infected brain: The role of the blood brain barrier
Authors: András Ibolya E. , Toborek Michal 
Published: December 2012

AbstractIn recent years, we face an increase in the aging of the HIV‐1‐infected population, which is not only due to effective antiretroviral therapy but also to new infections among older people. Even with the use of the antiretroviral therapy, HIV‐associated neurocognitive disorders represent an increasing problem as the HIV‐1‐infected population ages. Increased amyloid beta (Aβ) deposition is characteristic of HIV‐1‐infected brains, and it has been hypothesized that brain vascular dysfunction contributes to this phenomenon, with a critical role suggested for the blood‐brain barrier in brain Aβ homeostasis. This review will describe the mechanisms by which the blood‐brain barrier may contribute to brain Aβ accumulation, and our findings in the context of HIV‐1 infection will be discussed. © 2012 IUBMB Life, 65(1):43–49, 2013
Noninvasive blood glucose monitoring during oral intake of different sugars with optical coherence tomography in human subjects
Authors: Zhang Yuqing , Wei Huajiang , Yang Hongqin , He Yonghong , Wu Guoyong , Xie Shusen , Zhu Zhenguo , He Ruoyu 
Published: December 2012

AbstractThe potential of OCT applied to noninvasive blood glucose monitoring has attracted significant efforts. In this work we investigated the feasibility of OCT in monitoring blood glucose during oral intake of different sugars in humans. Five groups of experiments were performed, in which different sugars were used. The OCT signal slope (OCTSS) changed with variation of blood glucose concentration (BGC). A good correlation between OCTSS and BGC was observed in these experiments. The averaged correlation coefficients R between OCTSS and BGC are 0.900, 0.836, 0.895 and 0.884, corresponding to oral administration of glucose, fructose, sucrose and mixed sugar, respectively. Our studies demonstrated the capability and accuracy of the OCT system in monitoring BGC noninvasively and it could become a powerful tool in daily blood glucose monitoring for patients. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)