cssi/SciSciGPT-SciSciNet huggingface dataset:
l-Phenylalanine ammonia-lyase: IV. Evidence that the prosthetic group contains a dehydroalanyl residue and mechanism of action

Abstract l -Phenylalanine ammonia-lyase from potato tubers upon reduction with tritiated NaBH4 gave Type I tritiated enzyme. The nature of the reduction procedure, the observed correlation between loss of enzyme activity and tritium incorporation, and the magnitude of the incorporation suggested that reduction of an electrophilic center at the active site took place, and that one atom of hydrogen from borohydride is incorporated per active site reduced. Upon HCl hydrolysis, Type I tritiated enzyme gave exchangeable tritium and dl alanine-t in which most, but probably not all, of the tritium was in the β-position. It is proposed that the active site contains a dehydroalanyl residue which upon reduction yields a tritiated alanyl residue so substituted at the nitrogen atom that HCl hydrolysis leads to racemization and tritium loss. The unusual chemical environment of the alanyl residue is indicated by the mildness of the hydrolysis conditions necessary to release dl -alanine-β-t and the observation that Type I tritiated enzyme upon dilution and dialysis yielded exchangeable tritium and a new form of tritiated enzyme (Type II) which gave a neutral tritiated substance upon HCl hydrolysis. Guanidine hydrochloride also brings about the Type I to Type II conversion. The enzyme functions catalytically by converting the NH3+ of l -phenylalanine into a better leaving group. If the nitrogen of the dehydroalanyl residue is present as a Schiff's base masked against attack by such reagents as borohydride, then it is probable that the amino group of phenylalanine adds to the β-position of the dehydroalanyl double bond. If this intermediate undergoes a prototropic shift the conjugated system OCCαCβN may be formed (the three carbon atoms are those of the original dehydroalanyl residue and the nitrogen belongs to phenylalanine). With such a leaving group the free energy of the transition state in the elimination process should be lowered by resonance.
Integrating Pre-Registered Re-examinations (p-rex) Proposals into Research Programs and Doctoral Seminars

Accounting journals rarely publish articles explicitly focused on re-examining prior claims. Such articles allow accounting scholars to establish the validity and generality of claims that are or might become influential in our field. However, the professional benefits of revisiting claims are often believed to be outweighed by its costs, especially for junior scholars. This document explains how pre-registered re-examination proposals (p-rex), such as those recently solicited by Journal of Financial Reporting, enhance the net professional benefits of publishing re-examinations, and offers suggestions on how faculty can integrate p-rex proposals into their doctoral seminars.
Jean-Luc Godard et Maurice Pialat lisant Musset : rêves et restes d’une théâtralité romantique

This article investigates the traces of nineteenth-century aesthetics in films by two enfants terribles of cinema, namely Maurice Pialat and Jean-Luc Godard. It concentrates on the shared reference...
Pain severity and e-cigarette health literacy: the moderating role of sex.

Although electronic cigarette (e-cigarette) use has increased among adults in the United States, there is still little knowledge of factors that may influence e-cigarette use or beliefs about use. ...
Identification of management thresholds of urban development in support of aquatic biodiversity conservation

Abstract Urbanization degrades stream ecosystems and causes loss of bodiversity. Using benthic macroinvertebrates as a surrogate for overall aquatic diversity, we conducted a series of analytical approaches to derive management thresholds of urban development designed to link ecological responses to the primary management goal of protecting aquatic diversity in streams within the Delaware Water Gap National Recreation Area (USA). We were particularly interested in identifying urban thresholds that represent the early phases of biological impact to support cost-effect management and mitigation interventions. We used taxa-specific modeling approaches within a spatially-explicit framework to develop sensitive thresholds that anticipate and demark the onset of taxa loss and provide a foundation for investigating alternative mechanisms driving biological change. We identified an early-warning threshold of 1.5% urban development in the contributing watershed where 15% of the 107 taxa evaluated exhibited significant declines in abundance but prior to any evidence of extirpation, and an extirpation threshold of 6% urban development where nearly 3% of taxa are likely to be lost locally. These thresholds of urban development are substantially lower than response thresholds typically reported based upon traditional modeling approaches that rely on spatially-implicit summaries of land cover and univariate metrics or composite indices. An analysis of ecological and functional trait composition of taxa determined to be sensitive suggests that reduced storage of benthic organic matter caused by flashier hydrographs may be the primary mechanism driving biological changes observed at relatively low levels of urbanization. Although the extent to which stream communities respond to stressor gradients in a non-linear fashion continues to be debated, we show that threshold approaches can be applied in support of aquatic resource management irrespective of whether or not stress-response functions are non-linear.
Reserve prices eliminate low revenue equilibria in uniform price auctions

Abstract Uniform price auctions frequently admit equilibria which raise zero seller revenue. We show that when demand is sufficiently strong — when market supply is more than covered by any bidder's opponents — the introduction of a reserve price improves revenue not only by directly increasing the market clearing price, but also by eliminating low revenue equilibria in which the market clearing price is almost always equal to the reserve. The condition on demand is sharp, and when it is not satisfied there exist equilibria in which the market clearing price almost always equals the reserve. Our results therefore fully characterize the existence of low revenue equilibria in terms of bidder demand at a given reserve price. This sharp characterization extends directly to the case of stochastic supply, and low revenue equilibria also fail to exist when supply is stochastic and elastic.
Hydrogen metabolism in Rhizobium: energetics, regulation, enzymology and genetics

Publisher Summary Hydrogen (H 2 ) utilization can occur in aerobic and anaerobic bacteria and is linked to ATP-producing electron transport systems. The aerobic N 2 -fixing bacteria evolve and consume H 2 , and among this group are the rhizobia, the azotobacter , and the cyanobacteria. Hydrogen evolution by these micro-organisms is catalyzed by nitrogenase and an uptake hydrogenase is responsible for H 2 oxidation. Whereas the cyanobacteria have hydrogenase activity even in cells not fixing N 2 , hydrogenase is generally derepressed under N 2 -fixing conditions in Azotobacter and in hydrogen uptake positive (Hup+) strains of Rhizobium . In addition, the autotrophic growth of R. japonicum on H 2 has been demonstrated in the laboratory, and thus H 2 oxidation by this bacterium, without concomitant N 2 fixation, may conceivably occur in nature under some conditions. This chapter discusses H 2 metabolism in Rhizohium, particularly R. japonicum and R. leguminosarum . The enzymology of hydrogenase concentrates on R. japonicum because the R. leguminosarum enzyme has yet to be purified and characterized. Different approaches have been taken in studying genetic problems concerning H 2 metabolism in R. japonicum and R. leguminosarum.
Effects of a recurring late-night event on the behavior and welfare of a population of zoo-housed gorillas

The impact of visitors on the well-being of captive animals presents both positive and potentially negative consequences. While some amount of novelty through visitor stimulation offers the opportunity for a more complex captive environment, anecdotal evidence from primate staff observations at the Smithsonian's National Zoo and Conservation Biology Institute suggested that gorillas exhibited increased restlessness during the annual month-long late night ZooLights (ZL) event than before it. The current study compared activity budgets, aggression (interactions involving contact between conspecifics and displays toward visitors), and abnormal behaviors in two groups of socially housed gorillas for 1-month periods before, during, and after the 2015 ZL event. We also compared the fecal glucocorticoid metabolite profiles of all six gorillas across these same observation periods. Physiologically, most individuals appeared to cope appropriately with the increased visitor presence during the event. We saw little difference in contact aggression; however, abnormal behavior was observed in some gorillas during and after the event, which highlights the importance of individual analysis and data interpretation. As predicted, we found that the majority of gorillas rested less during ZL than during other observation periods, particularly adult females in the mixed sex troop. Preliminary results of this study aided the decision of zoo management to close initially the Great Ape House and subsequently most animal buildings during future ZL events to avoid the potential disruption of normal activity patterns. While the findings of this study were mixed as to the impact of the event on these gorillas, the results suggest that zoos should carefully consider the possible ramifications of keeping great ape buildings open for lengthy multi-night events.
Heparin as a Therapy for COVID-19: Current Evidence and Future Possibilities.

Coronavirus disease 2019 (COVID-19), the clinical syndrome associated with infection by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has impacted nearly every country in the world. Despite an unprecedented focus of scientific investigation, there is a paucity of evidence-based pharmacotherapies against this disease. Because of this lack of data-driven treatment strategies, broad variations in practice patterns have emerged. Observed hypercoagulability in patients with COVID-19 has created debate within the critical care community on the therapeutic utility of heparin. We seek to provide an overview of the data supporting the therapeutic use of heparin, both unfractionated and low molecular weight, as an anticoagulant for the treatment of SARS-CoV-2 infection. Additionally, we review preclinical evidence establishing biological plausibility for heparin and synthetic heparin-like drugs as therapies for COVID-19 through antiviral and anti-inflammatory effects. Finally, we discuss known adverse effects and theoretical off-target effects that may temper enthusiasm for the adoption of heparin as a therapy in COVID-19 without confirmatory prospective randomized controlled trials. Despite previous failures of anticoagulants in critical illness, plausibility of heparin for COVID-19 is sufficiently robust to justify urgent randomized controlled trials to determine the safety and effectiveness of this therapy.
Hybrid Endovascular Treatment of Dysphagia Lusoria: Report of 2 Cases:

Dysphagia Lusoria is a condition when aberrant right subclavian artery (ARSA) causes esophageal compression. We report 2 cases of Dysphagia Lusoria treated by hybrid endovascular technique which included subclavian to carotid transposition and embolization of origin of ARSA. By using this technique, we avoided the need for thoracotomy. Both patients had complete symptom relief without any surgery related complication.
Microtubules and Gαo-signaling independently regulate the preferential secretion of newly synthesized insulin granules in pancreatic islet β cells

For sustainable function, each pancreatic islet {beta} cell maintains thousands of insulin granules (IGs) at all times. Glucose stimulation induces the secretion of a small portion of these IGs and simultaneously triggers IG biosynthesis to sustain this stock. The failure of these processes, often induced by sustained high-insulin output, results in type 2 diabetes. Intriguingly, newly synthesized IGs are more likely secreted during glucose-stimulated insulin secretion. The older IGs tend to lose releasability and be degraded, which represents a futile metabolic load that can sensitize {beta} cells to workload-induced dysfunction and even death. Here, we examine the factor(s) that allows the preferential secretion of younger IGs. We show that {beta} cells without either microtubules (MTs) or Go signaling secrete a bigger portion of older IGs, which is associated with increased IG docking on plasma membrane. Yet Go inactivation does not alter the {beta}-cell MT network. These findings suggest that Go and MT regulate the preferential release of newer IGs via parallel pathways and provide two potential models to further explore the underlying mechanisms and physiological significance of this regulation in functional {beta} cells.
A Game Framework to Secure Control of CBTC Systems

To meet the growing railway-transportation demand, researchers have designed a new train control system, communication-based train control (CBTC) system, to maximize the ability of train lines by reducing the headway of each train. However, wireless communications expose the CBTC system to new security threats. Due to the cyber-physical nature of the CBTC system, a jamming attack can damage the physical part of the train system by disrupting the communications. To address this issue, this chapter develops a secure framework to mitigate the impact of the jamming attack based on a security criterion. At the cyber layer, we apply a multi-channel model to enhance the reliability of the communications and develop a zero-sum stochastic game to capture the interactions between the transmitter and jammer. We present analytical results and use dynamic programming to find the equilibrium of the stochastic game. We investigate a special case study to obtain insight results, showing a strong inter-dependency between the physical and cyber layers. Finally, the experimental results are provided to evaluate the performance of the proposed secure mechanism.
PERIPHERAL VASOCONSTRICTION IN TRANSITIONAL ELBW INFANTS

Background ELBW infants are vulnerable to cold stress during the transition from delivery room to intensive care. Infants produce heat by non-shivering thermogenesis (NST) and should exhibit peripheral vasoconstriction when cold, but little empirical evidence confirms that ELBW infants are capable of peripheral vasoconstriction. Objective This study evaluated the ability of ELBW infants weighing 400–1000 grams to exhibit peripheral vasoconstriction when body temperatures decreased. Design/Methods A within subject, multiple case design was used to explore the relationships between body temperature and peripheral vasoconstriction in 10 ELBW infants over their first 12 hours in the NICU. Abdominal temperature (AT) and peripheral temperature (PT) were measured in 1-min. intervals. Peripheral vasoconstriction is defined as AT 2°C above PT as established by Lyon et al. Each infant was evaluated for length of time spent with peripheral vasoconstriction. Results PT and AT were significantly correlated in each infant. One infant (BW: 880 gms) exhibited peripheral vasoconstriction and one infant (BW 960 gms) had AT 1°C greater than PT. Eight infants (BW: 510–720 gms) did not exhibit peripheral vasoconstriction. Seven infants spent at least 15% of their observations with PT > AT and these infants were most likely to have PT 1–2°C>AT. The peripheral-abdominal temperature difference increased during stressful procedures in some infants. Conclusions ELBW infants have little ability to vasoconstrict in response to NST. PT were more often > AT and this difference often increased during stressful clinical events. Vasomotor control appears immature at birth in infants
The MM-PAD-2.1: A Wide-Dynamic-Range Detector For High-Energy X-ray Imaging

We have fabricated 128×128 pixel readout ASICs for the MM-PAD-2.1, a wide-dynamic-range photon-integrating detector intended for high-energy x-ray imaging (>20 keV). Design specifications include a signal-to-noise ratio of 10 for measurement of a single 20-keV photon, a maximum measureable signal of 108 20-keV photons/pixel/frame, and the ability to accurately measure sustained photon rates of ≥ 109 20-keV photons/pixel/s. The pixel pitch is 150 µm, resulting in an active area of 19.2 mm × 19.2 mm per single-chip module. ASICs have been bonded to both Si and CdTe sensors. Detector control firmware has been designed that allows for selective readout of a 128×128 pixel area at 9 kHz, or readout of the full array at 1.5 kHz. First results from characterization of the full-scale chip are reported.
The Modern History of Probable Cause

It is frequently assumed that probable cause, roughly as we understand it today, has, since time immemorial, been the standard allowing an officer to search or arrest. The reality is that probable cause has change a lot since the Bill of Rights was drafted. In the mid-nineteenth century, probable cause was no more than a pleading requirement in criminal cases -- and never have been more than a pleading requirement in criminal cases. Victims of crimes alone were able to seek arrest or search warrants by swearing that they had suffered an injury and that they had probable cause to believe that the person identified committed the crime, or that evidence of the crime could be discovered in the place identified. The victim did not describe the factual basis of his suspicion. Probable cause as a pleading requirement for victims became inconsistent with late nineteenth century social regulations. In the latter half of the nineteenth century, states and the federal government created and punish victimless crimes. Prohibition, pornography and prostitution became targets of new government regulations. These new crimes required a mechanism to allow government searches and arrests without a victim's complaint. At the same time, professional police departments were emerging in American cities. This article accounts for the evolution of probable cause from the early nineteenth century pleading requirement to the modern evidentiary threshold requirment by looking at policing in New York City in the second half of the nineteenth century. While modern social regulations required a standard that public investigators could satisfy, distrust of the police prevented allowing police to simply plead probable cause as victims had done. A standard requiring police to offer facts supporting probable cause was thus born.
Simultaneous inhibition of the receptor kinase activity of vascular endothelial, fibroblast, and platelet-derived growth factors suppresses tumor growth and enhances tumor radiation response.

We have investigated the effect of simultaneous inhibition of multiple angiogenic growth factor signaling pathways on tumor growth, tumor blood perfusion, and radiation-induced tumor-growth delay using SU6668, an inhibitor of the receptor-tyrosine kinase activity of vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), and platelet-derived growth factor (PDGF). The SCK mammary carcinoma, FSaII fibrosarcoma, and CFPAC human pancreatic carcinoma were grown s.c. in the hind leg of A/J mice, C3H mice, and Balb/cAnNCrl-nuBr nude mice, respectively. Daily i.p. injection of 100 mg/kg of SU6668 markedly suppressed the growth of these three tumor types. SU6668 also markedly prolonged the survival time of host mice bearing SCK tumors, which appeared to be caused by a reduction of metastatic tumor growth in the lung. There was little or no change in normal tissue blood perfusion, whereas in SCK tumors the perfusion decreased by 50% at 1 h after a single i.p. injection of SU6668, slightly recovered at 4 h, and completely recovered by 8 h. Interestingly, the tumor blood flow was significantly increased above the baseline level 24 h after SU6668 injection. After extended daily i.p. injections of SU6668, the tumor blood flow in all of the three tumor types studied was markedly decreased compared with control. The observed effects of this drug on tumor blood perfusion may partially explain the effectiveness of the compound in suppressing tumor growth and extending survival of tumor-bearing mice. We also observed that daily SU6668 administration and a single dose of 15 Gy of X-irradiation was significantly more effective than either treatment alone in suppressing tumor growth. Our results suggest that SU6668 increased the radiosensitivity of tumor blood vessels. We conclude that SU6668 is a potent therapeutic agent potentially useful to suppress tumor growth and enhance the response of tumors to radiotherapy.
Suppression of potyvirus infection by coexpressed closterovirus protein.

Abstract A tobacco etch virus (TEV)-based expression vector has been used for insertion of several ORFs derived from the unrelated beet yellows virus (BYV). Hybrid TEV variants expressing the BYV capsid protein, 20-kDa protein, or HSP70 homolog systemically infected Nicotiana tabacum and stably retained BYV sequences. In contrast, insertion of the ORF encoding BYV leader proteinase (L-Pro) resulted in severely impaired systemic transport and accumulation of recombinant TEV. Progeny of this virus underwent various deletions affecting the L-Pro sequence and mitigating the defects in virus spread. Model experiments involving several spontaneous and engineered mutants indicated that the central domain of BYV L-Pro was responsible for the defect in hybrid virus accumulation, whereas full-size L-Pro was required for maximal debilitation of systemic transport. Strikingly, BYV L-Pro expression did not debilitate systemic infection of hybrid TEV in Nicotiana benthamiana plants. No major defects in replication or encapsidation of recombinant RNA were revealed in N. tabacum protoplasts. These results indicated that BYV L-Pro specifically interfered with TEV systemic transport and accumulation in a host-dependent manner and suggested a potential utility of closterovirus L-Pro as an inhibitor of potyvirus infection. In addition, it was demonstrated that the 107-amino-acid-residues-long N-terminal part of the TEV helper component proteinase is not essential for systemic infection.
Noise from Fine-Scale Turbulence of Nonaxisymmetric Jets

The noise from the fine-scale turbulence of high-speed nonaxisymmetric jets is considered. A prediction method is developed by extending the work of Tam and Auriault. A set of improved numerical boundary conditions for use in nonaxisymmetricjet mean flow and turbulence calculation is developed. These new boundary conditions allow the computation to be carried out in a smaller computation domain. It is known that nonaxisymmetric mean flow has a significant impact on the radiated noise spectrum and directivity through refraction. In the Tam and Auriault theory, this effect is accounted for by means of the adjoint Green's function. Here the adjoint Green's function method is extended to nonaxisymmetric mean flows. The adjoint Green's function is first recast into the solution of a sound scattering problem. The sound scattering problem is then solved computationally by computational aeroacoustics methods. Extensive comparisons between calculated and experimentally measured jet noise spectra are presented. They include both rectangular and elliptic jets at supersonic and subsonic Mach numbers
Nature and Scripture: Demise of a Medieval Analogy

Throughout the history of Christian thought the theological role of scripture as source of transcendent meaning has exercised considerable influence on the art and manner of biblical interpretation. In the early church the problems revolved mostly around the canon, specifically although not exclusively the New Testament, as defining the confines of scripture. The question arose, therefore, which biblical writings were divinely inspired and which were of doubtful origin. The latter were unacceptable for the Christian communities that had broken away from their ancestral Judaic religion. Even before the canon was fixed, however, the problems shifted from the divinely inspired composition of the Bible to its intrinsic signification; interpreters saw scriptural language itself as infused with theological content. As exegetical positions led to the development of credal statements that solidified into theological dogma, the early church established a link between biblical interpretation and sound doctrine. By enforcing sanctioned interpretations through effective excommunication, an ever more powerful church sealed the dominance of orthodoxy over heresy with the nearly divine force of ecclesiastical authority. In the church-dominated culture of the Middle Ages, the adequacy of scriptural interpretation—its method, its content, the credentials of its practitioners—often depended on its conformity with an expanding theological tradition.
Collective behavior of a coupled-map system with a conserved quantity.

We present the results of a numerical investigation of, and supporting analytic arguments for, the behavior of coupled sine maps with a locally conserved variable on a square lattice, with and without noise. By varying parameters we find two distinct conservation-induced routes to chaos: One is a first-order transition from a periodic 2-cycle phase with broken time-translational invariance and long-range, striped, spatial order, to a chaotic, spatially disordered phase in which time-translation invariance is restored; this transition is accompanied by a discontinuous jump in the maximum Lyapunov exponent, {lambda}{sub max}. The other is a continuous onset of temporal chaos occurring without any change in the spatial symmetry of the phase, which has striped ( antiferromagnetic'') long-range order on both sides of the chaotic onset. In this latter case, {lambda}{sub max} increases continuously from zero as the control parameter {ital R} is increased above the value {ital R}={ital R}{sup *} where chaos sets in; in the presence of noise, the numerics show {lambda}{sub max} growing {ital linearly} with {ital R}{minus}{ital R}{sup *}, in agreement with simple arguments. Numerical and analytic evidence (strong for the nonchaotic and weaker for the chaotic phases) is presented for the algebraic decay in time of autocorrelations.more » The asymptotic behavior of spatial correlations is also discussed. We also verify numerically the absence of collective chaos,'' i.e., of chaotic fluctuations of appropriately normalized Fourier amplitudes in the system, consistent with earlier arguments. We briefly discuss the relationship of these results to those of recent experiments on surface waves.« less
Runx1 modulates developmental, but not injury-driven, hair follicle stem cell activation

Aml1/Runx1 controls developmental aspects of several tissues, is a master regulator of blood stem cells, and plays a role in leukemia. However, it is unclear whether it functions in tissue stem cells other than blood. Here, we have investigated the role of Runx1 in mouse hair follicle stem cells by conditional ablation in epithelial cells. Runx1 disruption affects hair follicle stem cell activation, but not their maintenance, proliferation or differentiation potential. Adult mutant mice exhibit impaired de novo production of hair shafts and all temporary hair cell lineages, owing to a prolonged quiescent phase of the first hair cycle. The lag of stem cell activity is reversed by skin injury. Our work suggests a degree of functional overlap in Runx1 regulation of blood and hair follicle stem cells at an equivalent time point in the development of these two tissues.
Maintaining shortest paths under deletions in weighted directed graphs: [extended abstract]

We present an improved algorithm for maintaining all-pairs 1 + e approximate shortest paths under deletions and weight-increases. The previous state of the art for this problem was total update time ~O (n2√m/e) for directed, unweighted graphs [2], and ~O(mn/e) for undirected, unweighted graphs [12]. Both algorithms were randomized and had constant query time. Note that ~O(mn) is a natural barrier because even with a (1 + e) approximation, there is no o(mn) combinatorial algorithm for the static all-pairs shortest path problem. Our algorithm works on directed, weighted graphs and has total (randomized) update time ~O (mn log(R)/e) where R is the ratio of the largest edge weight ever seen in the graph, to the smallest such weight (our query time is constant). Note that log(R) = O(log(n)) as long as weights are polynomial in n. Although ~O(mn log(R)/e) is the total time over all updates, our algorithm also requires a clearly unavoidable constant time per update. Thus, we effectively expand the ~O(mn) total update time bound from undirected, unweighted graphs to directed graphs with polynomial weights. This is in fact the first non-trivial algorithm for decremental all-pairs shortest paths that works on weighted graphs (previous algorithms could only handle small integer weights).By a well known reduction from decremental algorithms to fully dynamic ones [9], our improved decremental algorithm leads to improved query-update tradeoffs for fully dynamic (1 + e) approximate APSP algorithm in directed graphs.
Multiple perspectives for collaborative navigation in CVE

Drawn from empirical studies on spatial cognition, this work explores ways of dynamically integrating others' perspectives and incorporating different views into a single interface for a 3D CVE user. It also designs an empirical study to test the effectiveness of different perspective displays on collaborative navigation performance.
Co-constructing efficacy: A “communities of practice” perspective on teachers’ efficacy beliefs

Abstract Teachers’ efficacy beliefs are critical to improving student learning, but we have yet to fully understand how these beliefs develop. The prevailing model of teachers’ efficacy development emerges from cognitive theories, but sociocultural theories may add insights to modeling the impact of teachers’ school contexts. This case study takes a “communities of practice” approach to explore the connections between teachers’ evidence-based decision-making practices and their efficacy beliefs. Findings, based on interviews with four teachers, indicate that teachers co-construct their efficacy beliefs in shared practices, suggesting the usefulness of communities of practice theory to more fully understand teachers’ efficacy belief development.
Challenges For The Use Of Holographic Elements In Optical Storage

Significant progress during the last several years has resulted in the successful development of read-only, write-once and erasable optical storage systems. Recently, several optical head desiu s have emerged in the literature that utilize holographic optical elements (HOEs) as replacements for convention. elements. The motivation is to reduce the numberof head components by capitalizing on the multifunctionality of an individual HOE, improve manufacturability, and reduce cost. There is also potential for improved drive performance by reducing the overall size and mass of the head. Following a brief review of 'conventional' optical head technology, this paper will describe design modifications utilizing HOEs, their impact on head performance, and the requirements that must be satisfied to permit wider usage. Emphasis will be placed on the issues associated with laser diode wavelength variability, high numerical aperture, high diffraction efficiency, and their use in magneto-optic systems where polarization considerations are important.
Thymectomy for Tumor and Myasthenia Gravis: A Ten Year Experience

Thymectomy is a procedure which is performed with minimum mortality and morbidity. It is definitive treatment for benign thymoma and in combination with irradiation therapy is the treatment of choice for malignant thymoma. The role of thymectomy in treatment of myasthenia gravis is indefinite. The occasional patient is dramatically benefited. So long as the procedure can be carried out a minimum risk, it should be considered in myasthenic patients in whom medical management has become unsatisfactory.
THE CARDIOVASCULAR EFFECTS OF INTRA VERTEBRAL ANGIOTENSIN II BEFORE AND AFTER TREATMENT WITH CLONIDINE

SUMMARY 1. In anaesthetized mongrel dogs it was shown that intravertebral infusions of angiotensin II (2–4 ng/kg per min) increased mean arterial pressure by causing an increase in cardiac output, while infusions of 10 ng/kg per min increased mean arterial pressure through an effect on peripheral resistance. After intravenous clonidine, intravertebral angiotensin no longer had any stimulatory effect on cardiac output, but arterial pressure still increased to the same extent. 2. It is concluded that intravertebral angiotensin can increase arterial pressure by increasing either cardiac output or peripheral resistance. The effects of intravertebral angiotensin on cardiac output can be reduced by concomitant stimulation of baroreflex pathways but its effects on peripheral resistance are not so readily antagonized.
A Highly Luminescent Tetranuclear Silver(I) Cluster and Its Ligation‐Induced Core Rearrangement

Rearrangement of the Ag4 cores of the luminescent silver(I) bis(diphenylphosphanyl)bipyridine (P2-bpy) complexes shown upon ligation of the Ag centers (see picture) leads to quenching of their emissions. Quenching occurs with O2, CO, NO, and with coordinating solvents such as MeCN and Me2SO. The reversible quenching of the emission of the halide-free complex [Ag4(P2-bpy)2]4+ in solution suggests potential applications as a sensor.
Use Of Multiple Time-Lapse Cameras For Traffic Studies

The use of time-lapse photography to study traffic behavior is well known to most traffic engineers. Inherent in its use, however, are at least two problems that have plagued engineers for many years: the high cost of equipment and the difficulty of photographing traffic on all approaches to an intersection with a single camera.
Ultrastructural studies of neuronal correlates of the pubertal reaugmentation of hypothalamic gonadotropin‐releasing hormone (GnRH) release in the rhesus monkey (Macaca mulatta)

This study tested the hypothesis that puberty in primates is triggered by a remodeling of synaptic inputs and/or glial coverage of hypothalamic gonadotropin releasing hormone (GnRH) neurons. Male rhesus monkeys were prepubertally castrated at 16 months of age and were killed and perfused either 1 month later (n = 4, juvenile group) or at 30 months of age, shortly after initiation of the pubertal increase in pulsatile GnRH release (n = 4, adult group). Hypothalami were sectioned, immunocytochemically stained for GnRH, and processed for electron microscopy. Cross-sectional profiles of 77 GnRH cells from the medial basal hypothalamus (MBH) and the region of the organum vasculosum of the lamina terminalis (OVLT) were compared between the two developmental stages. GnRH cell and nucleolus size in the two groups were the same. The percentage of GnRH perikaryal membrane occupied by synaptic density in the MBH of juveniles was significantly greater (P < 0.05) than that of adults. Differences in the percentage of GnRH perikaryal membrane occupied by synaptic density were not observed in the OVLT nor on GnRH dendrites in either brain region. Qualitative analysis, based on synaptic vesicle shape, failed to reveal developmental differences in putatively excitatory or inhibitory synapses on GnRH cells. The degree of glial ensheathment of GnRH neurons did not change significantly during the two developmental stages. These findings provide ultrastructural evidence for the view that, in primates, neuronal plasticity, and specifically a decrease in synaptic input to GnRH perikarya, may underlie the initiation of the pubertal mode of release of this neuropeptide, and therefore, the onset of puberty in these species.
Pharmacological Treatment of Vertigo

This review discusses the physiology and pharmacological treatment of vertigo and related disorders. Classes of medications useful in the treatment of vertigo include anticholinergics, antihistamines, benzodiazepines, calcium channel antagonists and dopamine receptor antagonists. These medications often have multiple actions. They may modify the intensity of symptoms (e.g. vestibular suppressants) or they may affect the underlying disease process (e.g. calcium channel antagonists in the case of vestibular migraine). Most of these agents, particularly those that are sedating, also have a potential to modulate the rate of compensation for vestibular damage. This consideration has become more relevant in recent years, as vestibular rehabilitation physical therapy is now often recommended in an attempt to promote compensation. Accordingly, therapy of vertigo is optimised when the prescriber has detailed knowledge of the pharmacology of medications being administered as well as the precise actions being sought. There are four broad causes of vertigo, for which specific regimens of drug therapy can be tailored. Otological vertigo includes disorders of the inner ear such as Meniere's disease, vestibular neuritis, benign paroxysmal positional vertigo (BPPV) and bilateral vestibular paresis. In both Meniere's disease and vestibular neuritis, vestibular suppressants such as anticholinergics and benzodiazepines are used. In Meniere's disease, salt restriction and diuretics are used in an attempt to prevent flare-ups. In vestibular neuritis, only brief use of vestibular suppressants is now recommended. Drug treatments are not presently recommended for BPPV and bilateral vestibular paresis, but physical therapy treatment can be very useful in both. Central vertigo includes entities such as vertigo associated with migraine and certain strokes. Prophylactic agents (L-channel calcium channel antagonists, tricyclic antidepressants, beta-blockers) are the mainstay of treatment for migraine-associated vertigo. In individuals with stroke or other structural lesions of the brainstem or cerebellum, an eclectic approach incorporating trials of vestibular suppressants and physical therapy is recommended. Psychogenic vertigo occurs in association with disorders such as panic disorder, anxiety disorder and agoraphobia. Benzodiazepines are the most useful agents here. Undetermined and ill-defined causes of vertigo make up a large remainder of diagnoses. An empirical approach to these patients incorporating trials of medications of general utility, such as benzodiazepines, as well as trials of medication withdrawal when appropriate, physical therapy and psychiatric consultation is suggested.
Alterations in the Secretory Response of Non-obese Diabetic (NOD) Mice to Muscarinic Receptor Stimulation

Salivary gland secretion in non-obese diabetic (NOD) and BALB/c mice was evaluated following stimulation with the muscarinic receptor agonist pilocarpine. Both saliva flow rates and total protein were similar in BALB/c and prediabetic NOD mice. With diabetes onset in NOD mice, the saliva flow rate and protein concentration were dramatically reduced. The level of cyclic AMP (cAMP) generated 10 min following agonist injection was similar for the parotid gland of BALB/c and prediabetic and diabetic NOD mice but was reduced in diabetic NOD mice. In the submandibular gland both prediabetic and diabetic NOD mice showed a reduced potential for the generation of cAMP compared with BALB/c mice. The parotid gland from NOD mice had elevated levels of basal and muscarinic receptor agonist (carbachol)-stimulated concentrations of inositol phosphate intermediates in in vitro assays compared with BALB/c animals, while in the submandibular gland of NOD mice, basal and agonist-stimulated concentrations of inositol phosphate intermediates were reduced relative to BALB/c. An evaluation of muscarinic receptor density showed a reduction with diabetes onset for the parotid gland, while a similar level was observed in prediabetic NOD and BALB/c mice. The receptor density was decreased for both the prediabetic and diabetic NOD submandibular glands compared with BALB/c animals. Sera from diabetic NOD but not BALB/c mice immunoprecipitated radiolabeled muscarinic receptor, indicating the presence of autoantibody to the receptor in diabetic mice. Thus, the reduction of muscarinic agonist response in NOD mice may be due, in part, to a generalized reduction in signal transduction components most evident in the prediabetic and diabetic submandibular gland and to a less certain degree in the parotid gland from diabetic NOD mice as a consequence of autoantibodies directed against cell surface antigens.
The Effects of Global Heliospheric Asymmetries on Energetic Neutral Atom Sky Maps

The relationship between the all-sky distribution of energetic neutral atoms (ENAs) observable at 1 AU and the distribution and structure of plasma in the outer heliosphere is a promising tool for probing the structure of the heliospheric boundaries. The impetus for this work stems from the anticipated 2008 launch of the Interstellar Boundary Explorer, which will directly measure ENA fluxes from Earth's orbit. We find, on the basis of global simulations, that the ENA flux depends sensitively on the shape of the heliopause as well as the velocity, density, and temperature of the postshock solar wind it envelopes. This Letter is intended as a preliminary, qualitative study of how ENA maps can help us identify heliospheric asymmetries.
E-procurement in services: the lagging application of innovation

E-procurement packages hold great potential to streamline processes and reduce purchasing costs. Interestingly, there appears to be a significant lag in the adoption of services e-procurement packages vis-a-vis goods e-procurement packages. A review of the extant literature on services e-procurement suggests the following four-category schema: (1) articles focusing on application service providers (2) articles focused on application users (3) articles focused on spend categories, and (4) valuation and viability studies. This schema is then used to frame a discussion of possible explanations for this observed lag in the adoption of an innovative and beneficial technology.
The role of Sb in the MBE growth of (GaIn)(NAsSb)

Abstract (GaIn)(NAs) can be grown pseudomorphically strained on GaAs with a very small band gap, opening up the possibility of achieving 1.3 or even 1.55 μm emission; however, wavelengths are actually limited by the N solubility limit and the high In strain limit. By adding Sb to the quaternary (GaIn)(NAs) we have observed a remarkable shift towards longer luminescent wavelengths, while maintaining good crystal quality. The growth of this now five-component system poses several challenges in regards to the epitaxial growth and the compositional characterization. The present paper elucidates the role of Sb as an alloy constituent as well as a surfactant in the growth of this pentanary alloy. The compositional changes of the material resulting from the addition of Sb will be shown.
Topical tissue factor pathway inhibitor improves free-flap survival in a model simulating free-flap errors

Free flap failure is frequently due to tension, twisting, kinking, or compression of the vascular pedicle after the anastomosis is completed. A rabbit model simulating these errors was used to evaluate the capacity of topically-applied tissue factor pathway inhibitor (TFPI) to prevent microvascular thrombosis. The rabbit ear was isolated on the central artery and vein. The artery was transected, shortened, repaired, and twisted 360 degrees around the vein. Immediately following the anastomosis. TFPI in concentrations of 1, 4, 10, or 40 micrograms/ml was irrigated across the lumen. Topically-applied control buffer and heparin (50 U/ml) were compared to TFPI. Treatment with control buffer resulted in a 20 percent survival rate. Topically-applied heparin improved the survival rate to 60 percent (p < 0.05). In contrast, TFPI in concentrations of 4, 10, and 40 micrograms/ml yielded survival rates of 89, 100, and 97 percent, respectively. This was significantly greater than the heparin-treated ears (p < 0.05). TFPI in a concentration of 40 micrograms/ml was effective in preventing arterial thrombosis when applied for as little as 30 sec; 4 micrograms/ml was effective in preventing thrombosis when applied for 10 min. These results support the use of TFPI as a topical irrigation solution to help prevent microvascular arterial thrombosis in free-flap surgery.
Concerning public transport as a reservoir of methicillin‐resistant staphylococci

The increase in methicillin-resistant Staphylococcus aureus (MRSA) infections in the nonclinical environment poses a serious public health concern (Eguia and Chambers 2003; Weber 2005). Surprisingly, the environmental (nonclinical) reservoirs and the routes of transmission of this pathogen in the community remain fairly uncharacterized (Chambers 2001; Weber 2005). In this regard Stepanovic et al. (2008) have provided a much needed and well designed study that investigated the public transport system as a possible reservoir of methicillin-resistant staphylococci (MRS) in an urban community. However, the absence of MRSA in this study might have been hastily concluded and because of deficiencies in the isolation method. The authors used a broth containing 4AE5% NaCl for initial enrichment of the samples, which was followed by isolation on mannitol salt agar (MSA) with 5AE5% NaCl. It has been established that concentrations higher than 2AE5% NaCl can be inhibitory for some MRSA strains (Bruins et al. 2007), while MSA fails to detect certain atypical mannitol-negative S. aureus strains (Shittu et al. 2007; Piau et al. 2008). Furthermore, it is not clear if the authors used positive and negative control strains to validate the MRSA isolation methodology. Additionally, a discussion of the hand rails material and environmental conditions (e.g. vehicle temperature, accessibility of rails to sun light, sampling season) would have been helpful for determining the possibility of MRSA occurrence and survivability on this surface. Consequently, linking the results of this study to the asymptomatic prevalence of MRS in the local community might be misleading. While the human hands are logically thought to be important means for MRS transmission, colonization and ⁄or carriage occurs on many locations on ⁄ in human body, notably the nasal cavities (Chambers 2001), which makes the former extrapolation difficult if not impossible.
Human microvascular endothelial cell-extracellular matrix interaction in cellular growth state determination.

We introduce two methods, both of which are based on cellular-extracellular matrix interaction, which will facilitate the study of human microvascular endothelial cells. One method describes the means to obtain a G1 population baseline in human microvasclular endothelial cells. Because of the contribution of the extracellular matrix in endothelial cell growth, synchronization in G1 was possible only after the incorporation of angiostatic levels of heparin and hydrocortisone into the extracellular matrix. In the second method, we demonstrate that selective perturbation of human microvascular endothelial cell-extracellular matrix interactions results in the induction of a transitional growth state, between proliferative and differentiated growth states, in human microvascular endothelial cells. In the functional, microtubule formation assays, transitional growth state endothelial cells display rates that are indermediate between those obtained from differentiated and proliferative endothelial cells. Our results demonstrate the importance of the human microvascular endothelial cell-extracellular matrix interaction in the determination of cellular growth state. Our findings also imply that responsiveness of microvascular endothelial cells to their cellular-extracellular matrix environs is highest during the differentiated growth state.