cssi/SciSciGPT-SciSciNet huggingface dataset:
Data-guided Multi-Map variables for ensemble refinement of molecular movies

Abstract Driving molecular dynamics simulations with data-guided collective variables offer a promising strategy to recover thermodynamic information from structure-centric experiments. Here, the 3-dimensional electron density of a protein, as it would be determined by cryo-EM or X-ray crystallography, is used to achieve simultaneously free-energy costs of conformational transitions and refined atomic structures. Unlike previous density-driven molecular dynamics methodologies that determine only the best map-model fits, our work uses the recently developed Multi-Map methodology to monitor concerted movements within equilibrium, non-equilibrium, and enhanced sampling simulations. Construction of all-atom ensembles along chosen values of the Multi-Map variable enables simultaneous estimation of average properties, as well as real-space refinement of the structures contributing to such averages. Using three proteins of increasing size, we demonstrate that biased simulation along reaction coordinates derived from electron densities can serve to induce conformational transitions between known intermediates. The simulated pathways appear reversible, with minimal hysteresis and require only low-resolution density information to guide the transition. The induced transitions also produce estimates for free energy differences that can be directly compared to experimental observables and population distributions. The refined model quality is superior compared to those found in the Protein DataBank. We find that the best quantitative agreement with experimental free-energy differences is obtained using medium resolution (∼5 A) density information coupled to comparatively large structural transitions. Practical considerations for generating transitions with multiple intermediate atomic density distributions are also discussed.
Chandra Observations of Variable Embedded X-Ray Sources in Orion. I. Resolving the Orion Trapezium

We used the High-Energy Transmission Grating Spectrometer on board the Chandra X-Ray Observatory to perform two observations, separated by 3 weeks, of the Orion Trapezium region. The zeroth-order images on the Advanced CCD Imaging Spectrometer provide spatial resolution of 05 and moderate energy resolution. Within a 160'' × 140'' region around the Orion Trapezium, we resolve 111 X-ray sources with luminosities between 7 × 1028 and 2 × 1032 ergs s-1. We do not detect any diffuse emission. All but six sources are identified. From spectral fits of the three brightest stars in the Trapezium, we determine the line-of-sight column density to be NH = (1.93 ± 0.29) × 1021 cm-2. Many sources appear much more heavily absorbed, with NH in the range of 1022-1023 cm-2. A large fraction of sources also show excursions in luminosity by more than a factor 5 on timescales greater than 50 ks; many are detected only in one of the observations. The main objective of this paper is to study the Orion Trapezium and its close vicinity. All five Trapezium stars are bright in X-rays, with θ1 Ori C accounting for about 60% of the total luminosity of the Trapezium. The CCD spectra of the three very early-type members can be fitted with a two-temperature thermal spectrum with a soft component of kT ~ 0.8 keV and a hard component of kT ~ 2-3 keV. θ1 Ori B is an order of magnitude fainter than θ1 Ori E and shows only a hard spectrum of kT ~ 3 keV. θ1 Ori D is another order of magnitude fainter than θ1 Ori B, with only a kT ~ 0.7 keV component. We discuss these results in the context of stellar wind models. We detect eight additional, mostly variable X-ray sources in the close vicinity of the Trapezium. They are identified with thermal and nonthermal radio sources, as well as infrared and optical stars. Five of these X-ray sources are identified with proplyds, and we argue that the X-ray emission originates from class I, II, and III protostars at the cores of the proplyds.
Trends in Ethnicity, Race, and Sex Among Psychiatry and Non-psychiatry Residency Applicants, 2008–2019

The objective of this study was to examine trends in racial/ethnic and gender representation among US psychiatry residency applicants compared with non-psychiatry applicants. Using publicly available applicant data, racial/ethnic and gender distributions of psychiatry residency applicants from 2008 to 2019 were examined and compared with non-psychiatry residency applicants. Both longitudinal trends within both cohorts and cross-sectional, between-group differences were examined. From 2008 to 2019, the percentage of female, American Indian/Alaskan Native (AIAN), Black, Hispanic, and Native Hawaiian/Other Pacific Islander (NHPI) psychiatry and non-psychiatry residency applicants increased (p<.001). Within each year, Black and Asian applicants comprised a larger percentage of psychiatry applicants compared with non-psychiatry applicants (p<.001). Between 2008 and 2019, Black psychiatry and non-psychiatry applicants increased from 9.1% to 11.6% and 6.6% to 7.6%, respectively; Asian psychiatry and non-psychiatry applicants decreased from 39.5% to 30.5% and 27.5% to 26.6%, respectively; White psychiatry and non-psychiatry applicants increased from 26.7% to 38.2% and 42.7% to 49.2%, respectively. Racial/ethnic and gender characteristics of US psychiatry residency applicants represent the future of the US psychiatric workforce. The US psychiatry residency applicant pool has become increasingly diverse from 2008 to 2019. Initiatives should work to enhance representation of psychiatry applicants from historically marginalized backgrounds, and simultaneously to recruit and retain a diverse psychiatric workforce following residency training.
Hybrid Control using Adaptive Particle Swarm Optimization and Integral Backstepping Control of Grid-connected Doubly Fed Induction Generator

We proposed an analysis of a hybrid control of active and reactive power for a doubly-fed induction generator for variable velocity wind energy injection into the electrical grid using a combination of adaptive particle swarm optimization and integral backstepping control in this paper. The stability of the Lyapunov function is utilized to establish the latter. Six controllers are developed as part of the proposed control process: The first is concerned with the maximum PowerPoint. The stator powers are managed by the second and third regulators, which are performed by the optimal PI controller using adaptive particle swarm optimization. The DC link voltage is kept constant by the fourth controller. The fifth and sixth are employed to pilot the rotor powers and ensure that the power factor is maintained to 1. These three controllers are synthesized by using the nonlinear integral backstepping control. These control strategies show excellent results compared to field-oriented control under a variable wind speed profile and changing generator settings in a Matlab/Simulink environment. According to the test findings, using integral backstepping, the overshoot of the DC-link voltage is decreased by 99.16 %. Furthermore, the particle swarm optimization reduces its time to reach the equilibrium state to 4.3 m s and demonstrates robustness against parameter generator changes. HIGHLIGHTS The regulation of the produced power by the wind energy conversion system (WECS) based on a doubly-fed induction generator is becoming increasingly important to researchers. This system is modeled and simulated in the Matlab/Simulink software environment to apply the proposed control In order to extract the maximum power from the variable wind source, a maximum power point tracking method is developed based on the PI controller For piloting the wind energy system conversion (WECS) based on a DFIG, a combination of the integrated Backstepping controller and adaptive PSO is proposed and realized in this paper Robustness tests are established by adjusting the generator parameters, and a comparative study is conducted to verify the superiority of the suggested control over the indirect vector control GRAPHICAL ABSTRACT
AMP-activated protein kinase inhibits transforming growth factor-β-mediated vascular smooth muscle cell growth: implications for a Smad-3-dependent mechanism

Dysfunctional vascular growth is a major contributor to cardiovascular disease, the leading cause of morbidity and mortality worldwide. Growth factor-induced activation of vascular smooth muscle cells (VSMCs) results in a phenotypic switch from a quiescent, contractile state to a proliferative state foundational to vessel pathology. Transforming growth factor-β (TGF-β) is a multifunctional signaling protein capable of growth stimulation via Smad signaling. Although Smad signaling is well characterized in many tissues, its role in VSM growth disorders remains controversial. Recent data from our lab and others implicate the metabolic regulator AMP-activated protein kinase (AMPK) in VSM growth inhibition. We hypothesized that AMPK inhibits VSMC proliferation by reducing TGF-β-mediated growth in a Smad-dependent fashion. Treatment of rat VSMCs with the AMPK agonist AICAR significantly decreased TGF-β-mediated activation of synthetic Smad2 and Smad3 and increased inhibitory Smad7. Flow cytometry and automated cell counting revealed that AICAR reversed TGF-β-mediated cell cycle progression at 24 h and elevated cell numbers at 48 h. TGF-β/Smad signaling increased the G0/G1 inducers cyclin D1/cyclin-dependent kinase (CDK) 4 and cyclin E/CDK2; however, AICAR reversed these events while increasing cytostatic p21. The specific role of Smad3 in AMPK-mediated reversal of TGF-β-induced growth was then explored using adenovirus-mediated Smad3 overexpression (Ad-Smad3). Ad-Smad3 cells increased cell cycle progression and cell numbers compared with Ad-GFP control cells, and these were restored to basal levels with concomitant AICAR treatment. These findings support a novel AMPK target in TGF-β/Smad3 for VSMC growth control and support continued investigation of AMPK as a possible therapeutic target for reducing vascular growth disorders.
Epigenetic Regulation of the Th2 Locus in Fetal and Neonatal T Cells

I n na¨ ove adult CD4 + T cells, the Th2 locus, containing the Il5, Il13, and Il4 genes, is in a transcriptionally quiescent state. When naT cells differentiate into Th2 cells, the Th2 locus undergoes extensive epigenetic modifications which are permissive for gene expression. These modifications, which include the induction of DNase I hypersensitivity, permissive histone modifications, and DNA demethylation at CpG residues, are associated with Th2 differentiation and secretion of Th2 cytokines. Regulatory regions, such as the Il4 and Il13 promoters, the locus control region (LCR), and intra- and intergenic enhancers are the primary targets of these modifications. Unlike adult animals, neonates are considered to be Th2 biased due to the robust development of Th2 lineage cells coupled with a deficiency in Th1 differentiation. This Th2 bias is reflected in the epigenetic status of the Th2 locus. In naneonatal CD4 + T cells in thymus and lymph nodes, key regulatory regions in the Th2 locus pre- exist in a hypomethylated state and these cells are already primed for Th2 status. Here, we focus on the epigenetic modifications in fetal and neonatal T cells and the association of the Th2 locus hypomethylated status with the characteristics of neonatal Th2 biased immunity.
Human Rights Genealogy

This chapter attempts to illuminate the status of prevailing international human rights theory by contributing a genealogical perspective to the contemporary theorizing. It examines the origins of the reigning theoretical framework by considering the historical and the political circumstances that attended the development of the theory. The chapter explains how a genealogical approach clarifies the problems in the reigning paradigm. It also explores further the dichotomies in the prevailing theory, thereby clarifying the puzzling status of the contemporary human rights theory. The chapter then examines the international human rights movement today, incorporating a genealogical perspective and clarifying the contemporary movement's intimate and uneasy relation to its original historical and political circumstances. Rights generation casts the human rights story in terms of the broader human condition—of scientific, historical, and political generations. Human rights practices emphasize the relationship between the international legal system and other legal domains.
Neuralized Mouse Embryonic Stem Cells Develop Neural Rosette-Like Structures in Response to Retinoic Acid and Produce Teratomas in the Brains of Syngeneic Mice

Several induction protocols can direct differentiation of mouse embryonic stem cells (ESCs) to become neural cells. The B5 and B6 mouse ESC lines display different growth patterns in vitro, and when grown as adherent cultures, the B6 ESCs proliferated at a significantly lower rate than B5 ESCs. Remarkably, after a neural induction protocol that includes removal of LIF and addition of retinoic acid (RA), mature B6 embryoid bodies (EBs) displayed a unique neural rosette-like morphology. On Day 8 of neural induction, B6 EBs revealed mature neuronal markers localized primarily to cells in the center of the EBs and glial markers expressed both in centrally and peripherally located cells. In contrast to B5 cells, when neuralized Day 8 B6 EB cells were dissociated and transplanted into the left striatum of syngeneic C57BL/6 mouse brains, teratomas formed. In addition, teratomas established from undifferentiated B6 cells grew more rapidly and achieved larger volumes when compared to those produced by Day 8, neuralized B6 EBs. The slow growth rate of B6 cells in vitro may have contributed to incomplete neuralization, formation of neural rosette-like structures, and a propensity to form teratomas.
Polymyxin-B stimulates tumor necrosis factor-alpha production by human peripheral blood mononuclear cells.

Abstract Gram-negative bacterial lipopolysaccharide (LPS) is a well known stimulus for cytokine production, particularly interleukin-1 (IL-1) and tumor necrosis factor alpha (TNF alpha). Polymyxin B (PMX-B) is a cationic polypeptide that binds to LPS, neutralizing its biological effects. PMX-B also disrupts gram-negative bacterial cell membrane phospholipids but is highly toxic to mammalian cells, therefore is of limited use. PMX-B is used as additive to media, as a way to handle LPS contamination. To derive benefit from the ability of PMX-B to neutralize lipid A in vivo while avoiding its systemic toxicity, PMX-B was covalently bound to polystyrene-derivative fibers, creating a hemoperfusion column (PMX-F) for the selective removal of circulating ET. In vitro PMX-F hemoperfusion studies have demonstrated effective ET removal, using either the Limulus amebocyte lysate assay or TNF alpha production by peripheral blood mononuclear cells (PBMC) as an index of ET removal. However, the question whether PMX-B itself could stimulate human PBMC to produce cytokines has not been adequately addressed. We examined the effect of increasing concentrations of PMX-B on cytokine production by PBMC in vitro. PBMC harvested from healthy volunteers were incubated for 24 hours at 37 degrees C with control (tissue culture media RPMI), or 5 microg/ml, 10 microg/ml, 20 microg/ml or 100 microg/ml PMX-B. At the end of 24 hours, PBMC were subjected to three freeze-thaw cycles, and total TNF alpha production (pg/2.5x10(6) PBMC) was measured by radioimmunoassay. Total TNF alpha production by PBMC was 163 +/- 3 pg, 171 +/- 9 pg, 164 +/- 4 pg, 323 +/- 63 pg and 331 +/- 58 pg, in the control, PMX-B 5 microg/ml, 10 microg/ml, 20 microg/ml and 100 microg/ml conditions, respectively. Compared to controls (RPMI), the percentage increase in TNF alpha production by PBMC was 5 +/- 6% (P=0.23), 1 +/- 3% (P=0.45), 99 +/- 40% (P=0.03) and 103 +/- 36% (P=0.02) in the presence of 5 microg/ml, 10 microg/ml, 20 microg/ml and 100 microg/ml of PMX-B, respectively. Furthermore, total TNF alpha production correlated significantly with increasing concentrations of PMX-B (R=0.53, P=0.007). We conclude that the use of PMX-B in in vitro studies as an LPS-neutralizing agent, or in the experimental treatment of endotoxic or septic shock can lead to erroneous interpretations of cytokine production by PBMC, and should be used cautiously in in vitro systems at high concentrations.
Enabling robots to find and fetch objects by querying the web

This paper describes an algorithm that enables a mobile robot to find an arbitrary object and take it to a destination location. Previous approaches have been able to search for a fixed set of objects. In contrast, our approach is able to dynamically construct a cost function to find any object by querying the web. The performance of our approach has been evaluated in a realistic simulator, and has been demonstrated on a companion robot, which can successfully execute plans such as finding a "coffee" and taking it to a destination location like, "Gates-Hillman Center, Room 7002."
Tissue interactions in embryonic mouse tooth germs: II. The inductive role of the dental papilla

The response of embryonic mouse dental epithelium and mesoderm to tissues of ectopic origin was examined. Isolated molar or incisor mesoderm was confronted with epithelium isolated from the plantar surface of the embryonic mouse foot plate or from the snout. Harmoniously structured teeth were formed from the foot epithelium and incisor or molar mesoderm. These data are interpreted as an unequivocal demonstration of the inductive role of the dental mesenchyme. Teeth were absent in confrontations of dental mesenchyme and snout epithelium. The presence of hair follicles in these explants is described and discussed with reference to other integumental epithelio-mesenchymal interactions. Dental epithelium forms keratinizing surface-like epithelium and invading bands of epithelium in association with foot mesoderm; definitive structures are not formed. On the other hand, when incisor or molar epithelium is associated with snout mesoderm, hair follicles are seen in addition to keratinizing surface-like epithelial configurations. The roles of the epithelial and mesenchymal tissues and the nature of epithelio-mesenchymal interactions in the developing mouse integument are discussed.
Melatonin biosynthesis: the structure of serotonin N-acetyltransferase at 2.5 A resolution suggests a catalytic mechanism.

Abstract Conversion of serotonin to N-acetylserotonin, the precursor of the circadian neurohormone melatonin, is catalyzed by serotonin N-acetyltransferase (AANAT) in a reaction requiring acetyl coenzyme A (AcCoA). AANAT is a globular protein consisting of an eight-stranded β sheet flanked by five α helices; a conserved motif in the center of the β sheet forms the cofactor binding site. Three polypeptide loops converge above the AcCoA binding site, creating a hydrophobic funnel leading toward the cofactor and serotonin binding sites in the protein interior. Two conserved histidines not found in other NATs are located at the bottom of the funnel in the active site, suggesting a catalytic mechanism for acetylation involving imidazole groups acting as general acid/base catalysts.
On Justification Conditional Models of Linguistic Competence

In 'What Dummett Says About Truth and Linguistic Competence', Richard Kirkham distinguishes a number of interpretations of Dummett's views on truth and meaning. After providing evidence that various interpreters have misunderstood Dummett, Kirkham lays out one of Dummett's arguments for the conclusion that truth conditional theories of meaning are without content, which supports the thesis that truth does not play a fundamental role in the theory of meaning. Finally, Kirkham attempts to refute Dummett's argument by offering a counter-example to the crucial premiss that the behaviour of competent speakers can be explained by appeal to implicit knowledge of justification conditions, without also attributing to them implicit knowledge of truth conditions distinct form justification conditions. I shall not address the issue of accuracy of interpretation or representation of Dummett's views. What I shall argue is that Kirkham's proposed counter-example does not succeed. Drawing on an example offered by Crispin Wright, Kirkham considers a speaker suffering from a congenital lack of a sense of taste. For such a person propositions like 'this is sweet' and 'this is salty' are undecidable, since there are circumstances in which she cannot ascertain their truth-values. Still, she knows justification conditions for such propositions, conditions largely in terms of the behaviour of the unafflicted when dealing with stuff that is sweet or salty. Wright also allows her the ability to discern relations of logical consequence between various attributions of taste to a substance (such as Kirkham's example, that 'this is salty or sweet' and 'this is not salty' entails 'this is sweet'), an ability which he thinks can be accounted for on the basis of her knowledge of justification conditions. Kirkham admits that this ability can be explained on a justification conditional model of meaning and lingusitic competence by use of an intuitionist/constructivist redefinition of 'logical consequence' in terms of justification conditions: X is a logical consequence of Y if and only if it is impossible for X not to be justified if Y iS (p. 221). (Hereinafter I adopt Kirham's convention of using double quotations to indicate this use of the expression, to distinguish it from the classically defined sense, for which no quotation marks are used.) However, although our tasteless person might assert
Repair of N-methylpurines in specific DNA sequences in chinese hamster ovary cells: absence of strand specificity in the dihydrofolate reductase gene

Abstract We have developed a quantitative method for examining the removal of N-methylpurines from specific genes to investigate their possible differential repair throughout the genome. Chinese hamster ovary cells were exposed to dimethyl sulfate, and the isolated DNA was treated with an appropriate restriction endonuclease. The DNA was heated to convert remaining N-methylpurines to apurinic sites to render them alkaline-labile. Duplicate samples heated in the presence of methoxyamine to protect the apurinic sites from alkaline hydrolysis provided controls to assess total DNA. After alkaline hydrolysis, agarose gel electrophoresis, Southern transfer, and probing for the fragment of interest, the ratios of band intensities of the test DNA sample to its methoxyamine-treated control counterpart were calculated to yield the percentage of fragments containing no alkaline-labile sites. The frequency of N-methylpurines was measured at different times after dimethyl sulfate treatment to study repair. We found no differences between the rates of repair of N-methylpurines in the active dihydrofolate reductase gene and a nontranscribed region located downstream from it in treated cells. Also, similar rates of repair were observed in the transcribed and nontranscribed strands of the gene, in contrast to previous results for the removal of cyclobutane pyrimidine dimers. Thus, there does not appear to be a coupling of N-methylpurine repair to transcription in Chinese hamster ovary cells. However, the repair in the dihydrofolate reductase domain appears to be somewhat more efficient than that in the genome overall. Our method permits the quantifying at the defined gene level of abasic sites or of any DNA adduct that can be converted to them.
Auditable Version Control Systems

Version control provides the ability to track and control changes made to the data over time. Software development often relies on a Version Control System (VCS) to automate the management of source code, documentation and configuration files. The VCS system stores all the changes to the data into a repository, such that any version of the data can be retrieved at any time in the future. Due to their potentially massive size, VCS repositories are often hosted at third parties which, unfortunately, are not necessarily trusted. Remote Data Checking (RDC) can be used to address concerns about the untrusted nature the VCS server by allowing a data owner to periodically and efficiently check that the server continues to store her data. To reduce the storage overhead, modern version control systems usually adopt “delta encoding”, in which only the differences (between versions) are recorded. As a particular type of delta encoding, skip delta encoding can optimize the combined cost of storage and retrieval. In this work, we introduce Auditable Version Control Systems (AVCS), which are VCS systems designed to function under an adversarial setting. We present the definition of AVCS and then propose RDC–AVCS, an AVCS scheme for skip delta-based VCS systems, which relies on RDC mechanisms to ensure all the versions of a file are retrievable from the untrusted VCS server over time. In RDC–AVCS, the cost of checking the integrity of all the versions of a file is the same as checking the integrity of one file version and the client is only required to maintain the same amount of client storage like a regular (non-secure) VCS system. We make the important observation that the only meaningful operation for real-world VCS systems which use delta encoding is append and leverage this observation to build RDC–AVCS. Unlike previous solutions which rely on dynamic RDC and are interesting from a theoretical point of view, we take a pragmatic approach and provide a solution for real-world VCS systems. We build a prototype for RDC–AVCS on top of a popular open-source version control system, Apache Subversion (SVN), and implement the most common VCS operations. Our security analysis and experimental evaluation show that RDC–AVCS successfully achieves the desired security guarantees at the cost of a modest decrease in performance compared to a regular (nonsecure) SVN system.
Patterns of larval source distribution and mixing in early life stages of Pacific cod (Gadus macrocephalus) in the southeastern Bering Sea

Abstract Effective and sustainable management depends on knowledge of spawning locations and their relative contributions to marine fish populations. Pacific cod ( Gadus macrocephalus ) in the southeastern Bering Sea aggregate at discrete spawning locations but there is little information on patterns of larval dispersal and the relative contribution of specific spawning areas to nursery habitats. Age-0 Pacific cod from two cohorts (2006 and 2008) were examined to address the following questions: (1) does size, age, and otolith chemistry vary among known capture locations; (2) can variation in elemental composition of the otolith cores (early larval signatures) be used to infer the number of chemically distinct sources contributing to juvenile recruits in the Bering Sea; and (3) to what extent are juvenile collection locations represented by groups of fish with similar chemical histories throughout their early life history? Hierarchical cluster (HCA) and discriminant function analyses (DFA) were used to examine variation in otolith chemistry at discrete periods throughout the early life history. HCA identified five chemically distinct groups of larvae in the 2006 cohort and three groups in 2008; however, three sources accounted for 80–100% of the juveniles in each year. DFA of early larval signatures indicated that there were non-random spatial distributions of early larvae in both years, which may reflect interannual variation in regional oceanography. There was also a detectable and substantial level of coherence in chemical signatures within groups of fish throughout the early life history. The variation in elemental signatures throughout the early life history (hatch to capture) indicates that otolith chemical analysis could be an effective tool to further clarify larval sources and dispersal, identify juvenile nursery habitats, and estimate the contributions of juvenile nursery habitats to the adult population within the southeastern Bering Sea.
Contingent faculty as teachers: What we know; what we need to know

Contingent faculty (full-time and part-time) who are not eligible for tenure or permanent employment provide a large portion of the instruction in U.S. higher education institutions, especially at ...
The Land Ethic Realized: Some Social Psychological Explanations for Changing Environmental Attitudes1

Changing environmental attitudes from an economic to a moral orientation are discussed in terms of the activation of moral norms to guide and evaluate behavior. In controlled experimental situations, increasing levels of two variables (awareness of the negative interpersonal consequences and ascription of responsibility) increased the likelihood that moral norms influenced behavior. Changes in the social system are discussed which have increased both our awareness of, and the actual adverse consequences stemming from, a strict economic approach to the environment. Other modifications have made decision-makers responsible for these consequences. These changes have fostered the current moral fervor concerning the natural environment.
Differential regulation of fasA and fasH expression of Escherichia coli 987P fimbriae by environmental cues

An early process in the pathogenesis of enteric bacteria is colonization of the intestinal epithelium leading to local multiplication, pathophysiological interactions with the host and further spreading. Attachment is typically mediated by bacterial fimbriae, which are selectively expressed during growth in the intestine. Here we report an analysis of the regulation of 987P fimbrial expression of enterotoxigenic Escherichia coli (ETEC). Expression of both fasH, the transcriptional activator of the 987P fimbrial genes, and fasA, the major fimbrial subunit, is regulated in response to a variety of environmental stimuli. We have found that expression of fasH is regulated in response to the carbon status of the growth medium by the cAMP-CRP complex. Moreover, fasH is regulated in response to both the nitrogen status of the growth medium and the external pH. Expression of fasA is activated by FasH, and is also selectively regulated in response to growth temperature by HNS. Regulation of fimbrial expression by carbon and/or nitrogen gradients is proposed to provide a mechanism that allows preferential colonization of different segments of the intestine by various enteropathogens, such as ETEC, enteropathogenic E. coli and Vibrio cholerae.
Physical and Sensory Characteristics of Low Fat Ground Beef Patties

Ground beef patties with combinations of 0 and 10% added water and 0 and 0.25% added phosphate were compared with controls (22% fat and 0% added water and phosphate). Added water increased thaw and cooking losses but improved objective texture measurements and sensory panel ratings (P < 0.05). Added water and phosphate increased the percentage of water, decreased protein and did not affect fat. Added water and/or phosphate resulted in higher (P < 0.05) juiciness, tenderness and overall palatability scores. Low fat patties with added water were similar to 22% fat patties. Water and/or phosphate also improved sensory ratings for texture and flavor of 10% fat patties to equal those for 22% fat patties.
Current pulsation of induction motor driving a reciprocating compressor

With a reciprocating-compressor drive, large errors in the prediction of current pulsation can occur when the induction-motor steady-state characteristics are used in the analytical solution. A numerical solution, in which the induction motor is represented by its general 2-axis equations, is presented, and the results favourably compared with test measurements. The currently used equation for induction-motor compressor factor is shown to be unsatisfactory, and a revision, involving the motor synchronising capability, is proposed.
Repeated Exposure to Conditioned Fear Stress Increases Anxiety and Delays Sleep Recovery Following Exposure to an Acute Traumatic Stressor

Repeated stressor exposure can sensitize physiological responses to novel stressors and facilitate the development of stress-related psychiatric disorders including anxiety. Disruptions in diurnal rhythms of sleep-wake behavior accompany stress-related psychiatric disorders and could contribute to their development. Complex stressors that include fear-eliciting stimuli can be a component of repeated stress experienced by humans, but whether exposure to repeated fear can prime the development of anxiety and sleep disturbances is unknown. In the current study, adult male F344 rats were exposed to either control conditions or repeated contextual fear conditioning for 22 days followed by exposure to either no, mild (10), or severe (100) acute uncontrollable tail shock stress. Exposure to acute stress produced anxiety-like behavior as measured by a reduction in juvenile social exploration and exaggerated shock-elicited freezing in a novel context. Prior exposure to repeated fear enhanced anxiety-like behavior as measured by shock-elicited freezing, but did not alter social exploratory behavior. The potentiation of anxiety produced by prior repeated fear was temporary; exaggerated fear was present 1 day but not 4 days following acute stress. Interestingly, exposure to acute stress reduced REM and NREM sleep during the hours immediately following acute stress. This initial reduction in sleep was followed by robust REM rebound and diurnal rhythm flattening of sleep / wake behavior. Prior repeated fear extended the acute stress-induced REM and NREM sleep loss, impaired REM rebound, and prolonged the flattening of the diurnal rhythm of NREM sleep following acute stressor exposure. These data suggest that impaired recovery of sleep / wake behavior following acute stress could contribute to the mechanisms by which a history of prior repeated stress increases vulnerability to subsequent novel stressors and stress-related disorders.
An Integrated Computer-Aided Engineering Approach for Parametric Investigation of Locked Plating Systems Design

Locked plating systems have emerged in recent years as effective devices for treating and stabilizing femoral fractures. Nevertheless, clinical failures due to plate yielding and fracture have been observed — particularly with distal femoral plates. The majority of failures are attributed to improper placement, fixation techniques, or plate selection, and to premature weight-bearing by the patient. While the mechanical function of plating systems is well-understood, the optimum design parameters that lead to efficient stability and fracture healing, such as plate geometry, material properties, and fixation techniques (e.g. screw configuration and the use of hole inserts), are unknown. The present paper presents an integrated computer-aided engineering (CAE) approach combining digital imaging, solid modeling, robust design methodology, and finite element analysis in order to conduct a parametric investigation of the design of locked plating systems. The present study allows for understanding the contributions of different design parameters on the biomechanics and reliability of these systems. Furthermore, the present approach will lead to exploration of optimum design parameters that will result in robust system performance. Three-dimensional surface models of cortical and cancellous femoral bone were derived via digital CT image processing techniques and a medical imaging analysis program. A nine orthogonal array matrix simulation (L9 ) was conducted using finite element methods to study the effects of the various design parameters on plate performance. The technique was demonstrated on a case study using a Smith & Nephew PERI-LOC distal femur locking plate where the plate thickness and material, the use of screw hole inserts, and the use of an oblique screw angled distally and medially were the design parameters. After creating a distal fracture with bone loss and stabilizing the femur with the plating system, the impact force due to walking was simulated on each of the nine fracture models. Results showed that increasing the plate’s thickness, using titanium alloy for fabrication, and using screw hole inserts in proximity to the fracture site will maximize the overall factor of safety.Copyright © 2010 by ASME
Combined Positron Emission Tomography–Computed Tomography: The Historical Perspective

The 1990s witnessed the development of the first dual-modality imaging devices for clinical applications. A combined PET-CT prototype underwent clinical evaluation from mid-1998 onward. The results from the three-year evaluation program stimulated the demand for commercial designs and in 2001 the first commercial PET-CT scanner was installed in the clinic. The availability of designs from all the major vendors of medical imaging equipment was followed by a rapid adoption of the technology and today, over 2500 PET-CT scanners are in clinical operation world-wide. This article briefly summarizes the short history of PET-CT, and reviews the current status of the technology.
Biochemistry and Physiology of Gastrointestinal Somatostatin

Somatostatin, a tetradecapeptide initially isolated from the ovine hypothalamus, is widely distributed throughout the gastrointestinal tract where it may act as a hormone, local chemical messenger, or neurotransmitter to elicit many physiological actions. Release of somatostatin from D cells in the gut is regulated by mechanisms that are both dependent on and independent of cAMP. In most cases somatostatin acts to inhibit the function of its target cells. It performs this action in part via pertussis-toxin-sensitive inhibitory guanine nucleotide-binding proteins that regulate adenylate cyclase activity. Other mechanisms may involve sites of action distal to intracellular second messenger systems.
Completeness of security markets and backward stochastic differential equations with unbounded coefficients

Abstract For a standard Black–Scholes-type security market, completeness is equivalent to the solvability of a linear backward stochastic differential equation (BSDE). When the interest rate is bounded, there exists a bounded risk premium process, and the volatility matrix has certain surjectivity, then the BSDE will be solvable and the market will be complete. However, if the risk premium process and/or the interest rate is not bounded, one gets a BSDE with unbounded coefficients to solve. In this paper, we will discuss such a situation and will present some solvability results for the BSDE which will lead to the completeness of the market.
Wide posets with fixed height and cutset number

Given an element x of a partial order P, a set S ⊂ P is said to be a cutset for x if S ∪ x meets every maximal chain of P and x is incomparable to every element of S. The cutset number of P is the minimum m such that every element of P has a cutset of size at most m. Let w(m, h) be the maximum width of a poset with height h and cutset number m. We determine the order of growth of w(m, h) for fixed m or fixed h: w(m, h)∈Θ(h⌊m/2⌋) for fixed m and w(m, h)∈Θ(mh) for fixed h.
Occupational hazards in medical education.

(1982). Occupational Hazards in Medical Education. Medical Teacher: Vol. 4, No. 4, pp. 124-125.
Reliability of BGA and CSP on Metal-Backed Printed Circuit Boards in Harsh Environments

In this study, the effect of metal-backed boards on the interconnect reliability has been evaluated. Previous studies on electronic reliability for automotive environments have addressed the damage mechanics of solder joints in plastic ball-grid arrays on non-metal backed substrates [Lall et. al 2003, Syed et. al 1996, Evans et. al 1997, Mawer et. al 1999] and ceramic BGAs on non-metal backed substrates [Darveaux et. al 1992, 1995, 2000]. Delamination of PCBs from metal backing has also been investigated. Increased use of sensors and controls in automotive applications has resulted in significant emphasis on the deployment of electronics directly mounted on the engine and transmission. Increased shock, vibration, and higher temperatures necessitate the fundamental understanding of damage mechanisms which will be active in these environments. Electronics typical of office benign environments uses FR-4 printed circuit boards. Automotive application typically use high glass-transition temperature laminates such as FR4-06 glass/epoxy laminate material (Tg = 164.9°C). In application environments, metal-backing of printed circuits boards is being targeted for thermal dissipation, mechanical stability and interconnections reliability. The test vehicle is a metal backed FR4-06 laminate. The printed circuit board has an aluminum metal backing, attached with pressure sensitive adhesive (PSA). Component architectures tested include – plastic ball grid array devices, C2BGA devices, QFN, and discrete resistors. Reliability of the component architectures has been evaluated for HASL. Crack propagation and intermetallic thickness data has been acquired as a function of cycle count. Reliability data has been acquired on all these architectures. Material constitutive behavior of PSA has been measured using uni-axial test samples. The measured constitutive behavior has been incorporated into non-linear finite element simulations. Predictive models have been developed for the dominant failure mechanisms for all the component architectures tested.© 2004 ASME
Determined theories and limit laws

We provide a new model theoretic technique for proving 0-1 and convergence laws. As an application, we obtain a new (slightly less computational) proof of convergence laws due to Spencer and Thoma for the probability functions: pnl = In(n)/n + lċIn(In(n))/n + c/n
Time-resolved gas temperatures in the oscillating turbulent flow of a pulse combustor tail pipe☆

Abstract The cyclic behavior of the gas temperature in the oscillating turbulent flow in a pulse combustor tail pipe was studied using two-line atomic fluorescence. In this flow, the oscillations result from an acoustic resonance, and have amplitudes of up to 5 times the mean velocity. Oscillation frequencies were varied from 67 to 101 Hz. Spatially resolved temperature measurements were made to within 400 μm of the wall, providing cycle-resolved profiles of the temperature and the random temperature fluctuations. The combustor-cycle phase relationships among the gas temperature, random-temperature-fluctuation intensity, velocity, and combustion chamber pressure, are compared. Velocity field effects dominated the cyclic behavior of the gas temperature, over the effects of isentropic compressive heating and the convection of hot pockets of gas from the combustion chamber. Cycle-resolved profiles show the gas temperature to be constant across the tail pipe, except for a boundary layer region, at all times during the cycle. Although cyclic temperature oscillations of more than 200 K were observed, the thermal boundary layer was well developed at all times during the cycle. The gas temperature was greater than the wall temperature at all cycle times, unlike the reversing velocity field, indicating that Reynolds analogy between momentum and thermal transport is not valid in this flow. Time-resolved wall heat flux was also measured and its fundamental oscillation is found to be in phase with that of the gas temperature.
Does the relation between volunteering and well-being vary with health and age?

Previous studies have established a positive association between organizational volunteering and well-being. In the current study, we examined whether the relations between organizational volunteering and positive affect, negative affect, and resilience are modified by respondents' age and number of chronic health conditions. This study used cross-sectional data from the 2008 Arizona Health Survey of residents 18 years old and older (N = 4,161). Multiple regression analyses provided no support for the hypothesis that age moderates the association between volunteer status and positive affect, negative affect, and resilience. In contrast, there was a significant (p < .05) interaction between volunteer status and chronic health conditions on positive affect and resilience. Consistent with the compensatory hypothesis, as number of chronic health conditions increased, the relations between volunteering and positive affect and resilience scores increased. Implications of these findings for increasing volunteeri...
Behavior Changes in Psychotherapy Groups: A Study Using an Empirically Based Statistical Method.

Methodological problems in charting phases of group development have created a tendency to overgeneralize existing theories in the field. An extensive review of the statistical methods used to chart group phases notes two methodological traps that reduce the utility of prevailing methods. A statistical methodology is suggested to avoid these traps. The model proposed allows description of the natural unfolding of behavior phases without destroying the multivariate richness of a group's activity. Using a Bales-type observational system to code behaviors of two psychotherapy groups, sessions were statistically clustered according to their behavioral similarity. These clusters were compared to identify distinct phases of development. A clinical description was prepared for each group using only the results obtained from the statistical model. Although similarities were found, it was shown that different groups develop differently, according to their own particular sets of internal and external pressures, and...
Research productivity and fellowship training in neurosurgery.

n the article by Agarwal et al. in this issue of WORLD NEUROSURGERY, the authors conclude that there is no I difference in research productivity—as measured by the h index—between those with and without fellowship training. Interpretation of the study findings must be made in the context of the evolving role of fellowship training in neurosurgery. Fellowship training is a relatively recent phenomenon in neurosurgery compared with other medical and surgical disciplines. The spectrum of diseases with potential neurosurgical interventions and the complexity of the requisite techniques for a given disease have led to the need for subspecialization and, consequently, subspecialty fellowship training. Senior faculty members are less likely to have undergone fellowship training than junior faculty members, simply because of the fact that fellowship training was much less common 20 years ago. As the study shows, the group of nonfellowship-trained neurosurgeons contained the greatest proportion of senior faculty members. Because senior faculty members also are more likely to have amassed substantial research work over their career than junior faculty, this confounds any true effect of fellowship training on research productivity.