cssi/SciSciGPT-SciSciNet huggingface dataset:
High‐pressure electron capture mass spectrometry

High-pressure Electron Capture Mass Spectrometry (HPECMS) has demonstrated extraordinarily high chemical specificity and sensitivity in the analysis of numerous compounds of environmental and biomedical interest. In the application of this technique, however, difficulties in the form of unexpected EC mass spectra and unexplainable variations of sensitivity are often noted. In this review article, two distinct sets of processes that determine the nature of the ions produced in an HPEC ion source are reviewed and discussed. The first set of gas-phase processes comprises the electron capture mechanism, leading to simple fragment and molecular anions. The second set of processes is imposed by physical realities of the typical HFEC ion source, These secondary processes can have large effects on the sensitivity of HPECMS to various types of EC-active compounds and can lead to the production of unexpected ions in HPEC mass spectra. It will be shown that the successful use of HPECMS is greatly facilitated by an understanding of all of the above interactive factors. The scope of this review is limited to the processes that will be important only under the relatively pristine ion source conditions that are typically established for the trace analysis of EC-active compounds introduced in very small quantities by capillary-column gas chromatography. © 1996 John Wiley & Sons, Inc.
An inductorless low-power tunable sinusoidal oscillator for micro-impedance spectroscopy

A sinusoidal oscillator is the stimulation source of a micro-impedance spectroscopy. The accuracy of its output frequency and waveform dictates the accuracy of the measured complex tissue impedance. In this study, an area-efficient low-power sinusoidal oscillator is developed for applications requiring low-power high-density bio-impedance measurements. Instead of using traditional LC tank based topology, the proposed sinusoidal oscillator implements a series of hyperbolic tangent functions to approximate the sine function. To achieve the continuous sinusoidal oscillation, a sine waveform shaper, a ramp signal generator, and a fully differential driver are developed for the proposed sinusoidal oscillator. To minimize the power dissipation, a low power supply voltage, 0.5 V, is used in the circuit. Designed in a standard 0.13-μm CMOS process, the proposed sinusoidal oscillator can generate continuous sinusoidal signal with a tuning range of 10 Hz-4 kHz. It dissipates power of 2 .
Low-temperature reforming of ethanol over CeO2-supported Ni-Rh bimetallic catalysts for hydrogen production

A new series of Ni-Rh bimetallic catalysts with different Ni and Rh loadings on a high-surface-area CeO2 was developed for the reforming of bio-ethanol at low-temperature (below 450 °C) to produce H2-rich gas for on-site or on-board fuel cell applications. Oxidative steam reforming of ethanol (OSRE) over a Ni-Rh/CeO2 catalyst containing 5 wt% Ni and 1 wt% Rh was found to be more efficient offering about 100% ethanol conversion at 375 °C with high H2 and CO2 selectivity and low CO selectivity compared to the steam reforming of ethanol (SRE) reaction which required a higher temperature of about 450 °C to achieve 100% ethanol conversion. The high temperature SRE reaction favors the formation of large amount of CO, which would make the downsteam CO cleanup more complicated for polymer electrolyte membrane fuel cell (PEMFC). The presence of O2 in the feed gas was found to greatly enhance the conversion of ethanol to produce H2 and CO2 as major products. Increase in Ni content above 5 wt% in the catalyst formulation decreased the H2 selectivity while the selectivity of undesirable CH4 and acetaldehyde increased. The 1 wt% Rh/CeO2 catalyst was twice as active as 10 wt% Ni/CO2 catalyst in terms of ethanol conversion and acetaldehyde selectivity and this indicated that Rh was more effective in C–C bond cleavage than Ni. The reaction was found to proceed through the formation of acetaldehyde intermediate, which subsequently underwent decomposition to produce a mixture of CO and CH4 or reforming with H2O and O2 to produce CO, CO2 and H2. The role of Rh is mainly to cleave the C–C and C–H bonds of ethanol to produce H2 and COx while Ni addition helps converting CO into CO2 and H2 by WGS reaction under the conditions employed.
Gas permeation and preconcentration in the flow-injection determination of acid-available cyanide in waste water

Abstract The determination of cyanide based on the reaction with highly selective sodium isonicotinate-3-methyl-1-phenyl-2-pyrazolin-5-one was optimized and compared with other spectrophotometric methods based on Konig's reaction. A reaction mechanism is proposed. The method, based on the formation of an intermediate product, allows a fast and highly sensitive determination of cyanide ions at concentrations from units to hundreds of μg l−1. The sampling frequency is 20 h−1 and the detection limit is 3 μg l−1 when 2.0 ml of sample are used. Most interferences, including those of CNS−, are eliminated by discrimination of mass transport through a non-porous silicone-rubber membrane.
Changes in Membrane Properties of Chick Embryonic Hearts during Development

The electrophysiological properties of embryonic chick hearts (ventricles) change during development; the largest changes occur between days 2 and 8. Resting potential (E(m)) and peak overshoot potential (+E(max)) increase, respectively, from -35 mv and +11 mv at day 2 to -70 mv and +28 mv at days 12-21. Action potential duration does not change significantly. Maximum rate of rise of the action potential (+V(max)) increases from about 20 v/sec at days 2-3 to 150 v/sec at days 18-21; + V(max) of young cells is not greatly increased by applied hyperpolarizing current pulses. In resting E(m) vs. log [K(+)](o) curves, the slope at high K(+) is lower in young hearts (e.g. 30 mv/decade) than the 50-60 mv/decade obtained in old hearts, but the extrapolated [K(+)](i) values (125-140 mM) are almost as high. Input resistance is much higher in young hearts (13 M ohm at day 2 vs. 4.5 M ohm at days 8-21), suggesting that the membrane resistivity (R(m)) is higher. The ratio of permeabilities, P(Na)/P(K), is high (about 0.2) in young hearts, due to a low P(K), and decreases during ontogeny (to about 0.05). The low K(+) conductance (g(K)) in young hearts accounts for the greater incidence of hyperpolarizing afterpotentials and pacemaker potentials, the lower sensitivity (with respect to loss of excitability) to elevation of [K(+)](o), and the higher chronaxie. Acetylcholine does not increase g(K) of young or old ventricular cells. The increase in (Na(+), K(+))-adenosine triphosphatase (ATPase) activity during development tends to compensate for the increase in g(K). +E(max) and + V(max) are dependent on [Na(+)](o) in both young and old hearts. However, the Na(+) channels in young hearts (2-4 days) are slow, tetrodotoxin (TTX)-insensitive, and activated-inactivated at lower E(m). In contrast, the Na(+) channels of cells in older hearts (> 8 days) are fast and TTX-sensitive, but they revert back to slow channels when placed in culture.
Matching the IEEE Test Feeder short circuit results

The IEEE Test Feeders provide a benchmark for the power distribution systems analysis community. This panel summary will provide a discussion of experiences matching the results published by Kersting and Shirek in this panel. [1] Benchmarking the short circuit currents for the Test Feeders is important to users of the Test Feeders for determining whether the system impedances are defined correctly and if the computational methods are sound. Results of the short circuit currents of various Test Feeders are provided as computed by the EPRI OpenDSS program. [2]
CVSys: a coordination framework for dynamic and fully distributed cardiovascular modeling and simulation

This paper presents a new framework, CVSys, for dynamic and fully distributed cardiovascular simulation with natural behavior flow and dynamic simulation control. This coordination framework uniquely incorporates attributes of open-endedness in terms of dynamic interactive entry of changing states during runtime, flexibility of event handling and system extensibility. The coordination framework relies on the autonomous object paradigm underlying a new distributed computing environment, MESSENGERS.
Development of Accident Modification Factors for Rural Frontage Road Segments in Texas

In some states, frontage roads are frequently used along freeway and fully controlled principal arterial corridors. Their primary function is to provide access between the arterial, or freeway, and adjacent developed property. Little information about the safety performance of rural frontage roads exists. This paper describes the development of a safety performance function (SPF) and accident modification factors (AMFs) for rural frontage road segments. Both one-way and two-way frontage road operations are addressed. The AMFs quantify the relationship between specific changes in geometric design and road safety. The findings from this research show that wider lanes and shoulders are associated with a reduction in segment-related collisions. In addition, the data suggest that the presence of edge marking has an impact on rural two-way frontage road safety. The SPF developed for this research indicates that, for the same traffic volume, rural frontage road segments experience about the same number of severe crashes as typical rural two-lane highways.
Construction of well separated interaction semigroups to refine the modeling of social networks

Abstract The techniques developed in this paper suggest an objective standard for the process that refines the generation of interaction semigroups associated with social networks. A constructed interaction semigroup S is assessed with respect to measurements used in the original construction. This information, summarized in the pair (m1, m2)(S) associated with the semigroup S, is a comparison of the closeness of the elements of the same class as compared to the closeness of the elements from distinct classes of S. It is desirable to have more separation between the elements from distinct classes and more “closeness” between the elements within a class. We use this idea to produce a separated interaction semigroup with more separation between distinct classes.
Anatomy, pathophysiology, andbiomechanics of shoulder instability

Abstract Instability in the athlete presents a unique challenge to the orthopaedic surgeon. A spectrum of both static anddynamic pathophysiology, as well as gross and microscopic histopathology, contribute to this complex clinical continuum. Biomechanical studies of the shoulder and ligament cutting studies in recent years have generated a more precise understanding of the individual contributions of the various ligaments and capsular regions to shoulder instability. An understanding of the underlying pathology and accurate assessment of degree and direction of the instability by clinical examination and history are essential to developing appropriate treatment algorithms.
Some lessons learned about risk reduction after ten years of the HIV / AIDS epidemic.

This article reviews some of the key facts concerning HIV risk behavior change the prevention lessons of the first decade of the AIDS epidemic. One of the most important developments over the past 10 years has been the marked increase in knowledge about the AIDS. More people are now aware of the measures for reducing the risk of contracting the disease -- using condoms and avoiding unprotected sex and needle-sharing. Risk reduction however is not determined by knowledge of risk alone. Researchers have identified a number of psychological behavioral and social factors that affect risk reduction. Studies also show that with gay male communities in large cities high-risk behavior has been reduced considerably. Recently however many gay men have relapsed back to unsafe sex. Additionally the studies have focused primarily on gay communities in large cities and have oversampled men who are white older better educated and of higher socioeconomic status than the rest of the gay community. Young non-white socially disadvantaged gay men as well as homosexuals who do not identify with the gay lifestyle stand in need of prevention efforts. While health promotion efforts have succeeded in curbing needle-sharing among intravenous drug users it has been difficult to change this groups sexual risk behavior. But the groups that remain the most impenetrable concerning changes in risk behavior are women and adolescents. Specific intervention approaches for women are not known. Additionally AIDS prevention programs for women often run up against cultural and social issues relating to family power structure. And for adolescents risk-reduction programs remain at an early stage of development.
Advancing the Understanding of Craving During Smoking Cessation Attempts: A Demonstration of the Time-Varying Effect Model

Introduction Advancing the understanding of smoking cessation requires a complex and nuanced understanding of behavior change. To this end, ecological momentary assessments (EMA) are now being collected extensively. The time-varying effect model (TVEM) is a statistical technique ideally suited to model processes that unfold as behavior and nicotine dependence change. Coefficients are expressed dynamically over time and are represented as smooth functions of time. Methods The TVEM approach is demonstrated using data from a smoking-cessation trial. Time-varying effects of baseline nicotine dependence (a time-invariant covariate) and negative affect (a time-varying covariate) on urge to smoke during a quit attempt were estimated for monotherapy, combination therapy, and placebo groups. SAS syntax for conducting TVEM is provided so that readers can adapt it for their research. Results During the first 2 days after quitting, the association between negative affect and craving was significantly stronger among individuals in the placebo group, suggesting an early positive impact of treatment. For the monotherapy and combination therapy groups, during the second week of the quit attempt, baseline dependence was less strongly related to craving compared with the placebo group, indicating a different positive impact of treatments later in the quit attempt. Conclusions The results reveal information about the underlying dynamics that unfold during a quit attempt and how monotherapy and combination therapy impact those processes. This suggests possible mechanisms to target in an intervention and indicates timepoints that hold the greatest promise for effective treatment. TVEM is a straightforward approach to examining time-varying processes embedded in EMA.
A Method for Analyzing Nonlinear Models When the Data are from a Split‐plot or Repeated Measures Design

Statistical methods are described which can be used to compare treatments where the response model is nonlinear and the experimental design includes split-plots or repeated measures. The nonlinear analysis of covariance is described for a two-way treatment structure in a split-plot design structure, the usual split-plot experimental design. Evaluating heat tolerance in common beans as a function of temperature is used as an example to demonstrate the methodology.
Sleep-Related Dissociative Disorder in a 6-Year-Old Girl

Sleep-related dissociative disorders are parasomnias that can emerge at any point during the sleep period and are associated with traumatic life experiences. No reports to date have described this parasomnia in a school-age child. This case report discusses presentation, diagnosis, and treatment of a 6-year-old girl with this diagnosis. Sleep-related dissociative disorder should be considered in young children who have experienced traumatic life events and who present with abnormal sleep patterns and bizarre behavior. Early identification and intensive psychotherapy can be efficacious for these children.
Hemorheology and the Flow Behavior in a Separated Flow Region

Separating flows can be encountered in the cardiovascular circulatory system and many biomedical applications such as artificial organs, rotary blood pumps, heart valves, stents, catheters, and probes. The current study investigates the influence of hemorheology on the flow behavior in a confined separated flow region. Recent hemorheological models and data are utilized to account for the yield stress and shear-thinning non-Newtonian characteristics of human blood. The flow field information is obtained by numerically solving the governing mass and momentum conservation equations along with the Herschel-Bulkley rheological model. The yield shear-thinning model always results in the smallest flow separation region. The yield stress and shear-thinning non-Newtonian models predict lower recirculation strength in comparison with the Newtonian model.Copyright © 2013 by ASME
Compact modeling of amorphous‐silicon thin‐film transistors with BSIM3

— A novel approach of modeling a-Si:H TFTs with the industry-standard BSIM3 compact model is presented. The described approach defines the a-Si:H TFT drain current and terminal charges as explicit functions of terminal voltages using a minimum set of BSIM3 parameters. The set of BSIM3 parameters is chosen based on the electrical and physical characteristics of the a-Si:H TFT and their values extracted from measured data. By using the selected BSIM3 model parameters, the a-Si:H TFT is simulated inside SPICE to fit the simulated I-V and C-V curves with the measured results. Finally, the extracted BSIM3 model is validated by simulating the kickback voltage effect in an AMLCD pixel array.
Accommodation of perioral tonus after insertion of complete dentures

Findings of an investigation to determine the magnitude of perioral tonus and the pattern of muscular accommodation after the extraction of teeth and prosthetic treatment indicated that, before prosthetic registration, interim dentures should be used as stabilizers of proprioceptive mechanisms.
Note on the availability of topside sounding data

A brief explanation is given on where to obtain ionospheric data generally, and specifically ionospheric data which has been observed from space vehicles. The close relations between the World Data Centers and the National Archives is noted.
On Brewer's class of robust sampling designs for large-scale surveys

In this note we observe that Brewer's (1979) result concerning the asymptotically design unbiased strategy which has minimum expected variance under a super population model can be established in a more general setting.
A boundary model for the thermal creep problem

A new integral boundary condition model for determining the particle velocity distribution function in a Knudsen layer, which makes it possible to improve the accuracy of the moment approximations, is proposed. The results for various models are compared with the exact numerical solution of the problem.
RNA expression patterns change dramatically in human neutrophils exposed to bacteria

A comprehensive study of changes in messenger RNA (mRNA) levels in human neutrophils following exposure to bacteria is described. Within 2 hours there are dramatic changes in the levels of several hundred mRNAs including those for a variety of cytokines, receptors, apoptosis-regulating products, and membrane trafficking regulators. In addition, there are a large number of up-regulated mRNAs that appear to represent a common core of activation response genes that have been identified as early-response products to a variety of stimuli in a number of other cell types. The activation response of neutrophils to nonpathogenic bacteria is greatly altered by exposure to Yersinia pestis, which may be a major factor contributing to the virulence and rapid progression of plague. Several gene clusters were created based on the patterns of gene induction caused by different bacteria. These clusters were consistent with those found by a principal components analysis. A number of the changes could be interpreted in terms of neutrophil physiology and the known functions of the genes. These findings indicate that active regulation of gene expression plays a major role in the neutrophil contribution to the cellular inflammatory response. Interruption of these changes by pathogens, such as Y pestis, could be responsible, at least in part, for the failure to contain infections by highly virulent organisms.
Bacteriologic features of surgical site infections following breast surgery.

Abstract Background Perioperative antibiotic prophylaxis to prevent surgical site infections (SSIs) after breast surgery is common practice. Breast SSIs were investigated to determine bacterial isolates, resistance patterns, and the appropriateness of cefazolin, the authors' institution's current regimen for perioperative antibiotic prophylaxis. Methods A retrospective review of 53 patients with culture-positive breast SSIs between June 1997 and August 2008 identified patient characteristics, bacterial isolates, and microbial resistance patterns. Results Among the 53 patients with positive cultures, 42% (n = 22) had undergone mastectomy, and 34% (n = 18) had undergone lumpectomy. Sixty-three bacterial isolates were identified, with 15% of SSIs being polymicrobial. Of the isolates, 49% (n = 31) were gram-negative bacteria. There was only 1 case of methicillin-resistant Staphylococcus aureus. Eight of 63 (13%) gram-negative isolates were cefazolin resistant. Conclusions Gram-negative SSIs constituted half of the SSIs in this breast surgery cohort. Of all breast isolates, 17.5% were resistant to cefazolin. On the basis of these findings, antibiotic prophylaxis regimens alternative to cefazolin should be considered.
Does local thermodynamic equilibrium exist in the excitation process of sputtered atoms

Abstract The optical line intensities from a series of ion-bombarded oxide glasses are fitted to two different equations relating the intensity and the energy of the upper level. The plots suggest that the existence of local thermodynamic equilibrium in the excitation process during sputtering is unlikely.
AUTO-SMASH: A self-calibrating technique for SMASH imaging

Recently a new fast magnetic resonance imaging strategy, SMASH, has been described, which is based on partially parallel imaging with radiofrequency coil arrays. In this paper, an internal sensitivity calibration technique for the SMASH imaging method using self-calibration signals is described. Coil sensitivity information required for SMASH imaging is obtained during the actual scan using correlations between undersampled SMASH signal data and additionally sampled calibration signals with appropriate offsets ink-space. The advantages of this sensitivity reference method are that no extra coil array sensitivity maps have to be acquired and that it provides coil sensitivity information in areas of highly non-uniform spin-density. This auto-calibrating approach can be easily implemented with only a small sacrifice of the overall time savings afforded by SMASH imaging. The results obtained from phantom imaging experiments and from cardiac studies in nine volunteers indicate that the self-calibrating approach is an effective method to increase the potential and the flexibility of rapid imaging with SMASH.
Hypoxia tolerance of two centrarchid sunfishes and an introduced cichlid from karstic Everglades wetlands of southern Florida, U.S.A.

In this study, the hypoxia tolerance of three Everglades fishes, two native centrarchids (Lepomis gulosus and Lepomis marginatus) and a recently introduced cichlid (Hemichromis letourneuxi), were documented. Aquatic surface respiration (ASR) thresholds were lowest for H. letourneuxi, followed by L. gulosus, then L. marginatus. The ASR thresholds for L. marginatus were within ranges reported for small, freshwater tropical fishes, while those for L. gulosus were similar to swamp-adapted fishes. For H. letourneuxi, ASR thresholds were some of the lowest reported. All three species showed excellent tolerance of low dissolved oxygen levels when allowed access to the surface. When denied surface access, L. marginatus lost equilibrium at a higher oxygen tension than the other species. Overall, although all species easily tolerated hypoxia, H. letourneuxi appeared to be best equipped to deal with hypoxia, followed by L. gulosus, then L. marginatus. Hemichromis letourneuxi also exhibited more aggressive behaviours than the centrarchids. These results suggest that hypoxia is not likely to prevent H. letourneuxi from exploiting the seasonally inundated wetlands of south Florida while expanding its range there.
Automated design of tier buildings

Abstract A computer program for the automated design of frameworks in steel tier buildings is described and demonstrated. The design process commences with the input of any initial set of member sies for a given geometry: it is not necessary to begin with good estimates. Cyclic analyses of the building frame and revisions of member sizes then follow. The three-dimensional analysis of the building frame includes the effects of the finite dimensions of moment-resisting connections. Within each cycle of design, wide-flange members are selected on the basis of satisfying the dead- and live-load stress requirements of the 1969 AISC Specification for Structural Steel in Buildings. Each member is then checked for the most critical combination of vertical and lateral loading. The lightest satisfactory size within a prespecified range of sizes is ultimately selected. The output consists of beam and column schedules that show the final sizes and the design conditions leading to their selection. Sample three-story and twenty-story building designs show consistent and rapid convergence to a final design without human intervention between consecutive cycles. With highrise buildings becoming increasingly prevalent, an economical automated design procedure should be of great value to the practicing structural engineer.
Smoking policy in pediatric hospitals and wards.

• The American Academy of Pediatrics has recommended that pediatricians take the lead in banning cigarette smoking in all pediatric health care facilities. This study investigated the use of "nonsmoking" policies and their planned revisions, problems in enforcement, and any history of challenges to restrictive or lenient policies. The surveys were mailed to 329 hospitals affiliated with pediatric training programs as the institutions most likely to attempt to comply with the American Academy of Pediatrics recommendations. Representatives from 199 (60%) of the programs responded. The programs had a range of 12 to 350 pediatric beds in children's hospitals (27%), pediatric wards (69%), or general hospitals (4%). Only nine hospitals were "smoke-free," ie, having no designated indoor area for smoking. Another 35 had "restrictive" policies allowing smoking in only a single site or two preselected sites. Pediatric hospitals or wards were no more likely to have smoke-free policies than general hospitals. Existence of smoke-free or restrictive policies was unrelated to any other factor examined. Smoke-free and restrictive policies were more likely to be rigorously enforced but not more likely to engender formal challenges. Although almost all policies had been recently or are being revised, pediatric hospitals and wards remain remiss in controlling childhood smoke exposure. ( AJDC . 1989;143:567-569)
The equivalence between two definitions of digital surfaces

Digital surfaces deal with properties of surfaces in digital spaces. In the early 80's, researchers began to establish definitions for digital surfaces. Unlike surfaces in continuous spaces, digital surfaces have different characteristics. A general and intuitive definition for digital surfaces is still an open problem. This paper presents a proof of the equivalence of two digital surface definitions. One of the definitions was developed based on simple surface points given by Morgenthaler and Rosenfeld [1], and the second uses a parallel-move concept as given by direct adjacency [2,3]. A by-product of this proof of equivalence is that any simple surface point in a simple surface belongs to one of six types of simple surface points.
Medical Relation Extraction with Manifold Models

In this paper, we present a manifold model for medical relation extraction. Our model is built upon a medical corpus containing 80M sentences (11 gigabyte text) and designed to accurately and efciently detect the key medical relations that can facilitate clinical decision making. Our approach integrates domain specic parsing and typing systems, and can utilize labeled as well as unlabeled examples. To provide users with more e xibility, we also take label weight into consideration. Effectiveness of our model is demonstrated both theoretically with a proof to show that the solution is a closed-form solution and experimentally with positive results in experiments.
Improving the Performance of TCP Wireless Video Streaming with a Novel Playback Adaptation Algorithm

In this paper we propose a playback adaptation algorithm for video streaming with TCP in wireless networks where both handoffs and random wireless errors are possible. Primary task of the algorithm is the estimation of the expected latency for the delivery of the lost packets by TCP. After this procedure is performed, the client adjusts the playback rate according to our algorithm so that both buffer underflows and overflows can be avoided. The proposed algorithm in non-intrusive to the protocol stack since it does not require any modifications to the baseline TCP protocol. To validate the basic principles behind our idea, we provide a set of comparative experimental results with other TCP-based streaming systems in terms of the rate of underflow events and the PSNR.
Effects of time-in-clinic, clinic setting, and faculty supervision on the continuity clinic experience.

STUDY OBJECTIVE: To evaluate the effects of setting, type of supervision, and time in clinic on the resident continuity clinic experience. DESIGN: Prospective cohort with preintervention and postintervention measures. SETTINGS: Pediatric residents selected one of three clinic settings for their continuity clinic experience. These included a traditional, university-based clinic, private practice offices, and publicly funded community-based clinics. SUBJECTS: All pediatric residents at the University of Utah Health Sciences Center, July 1985 through June 1991. INTERVENTIONS: Using varied clinic sites, matching residents one or two to one with preceptors for their continuity clinic, increasing continuity clinic from 1 to 2 half-days per week. MEASUREMENTS AND MAIN RESULTS: Residents in private offices had the most varied experience, seeing more patients, more acute care, and a broader age range of patients than residents at other sites. They were more likely both to be observed by their preceptors during patient visits and to observe their preceptors delivering care. Because the number of patients seen per session rose, increasing continuity clinic time from one to two half-days per week more than doubled the number of patients seen per week. Increased time away from hospital did not affect scores on the Pediatric In-Training Examination. While test scores were similar for incoming residents, those in private offices scored higher on the final Behavioral Pediatrics Examination (P < .05). CONCLUSIONS: Clinic setting, time in clinic, and faculty supervision affect the quality of the continuity clinic experience. Increased time in clinic resulted in a broader exposure to patients. Residents placed in private offices had a more varied patient mix, were more closely supervised, and seemed to gain primary care skills more rapidly than residents at other sites.
Chromatin dynamics during repair of chromosomal DNA double-strand breaks

The integrity of a eukaryotic genome is often challenged by DNA double-strand breaks (DSBs). Even a single, unrepaired DSB can be a lethal event, or such unrepaired damage can result in chromosomal instability and loss of genetic information. Furthermore, defects in the pathways that respond to and repair DSBs can lead to the onset of several human pathologic disorders with pleiotropic clinical features, including age-related diseases and cancer. For decades, studies have focused on elucidating the enzymatic mechanisms involved in recognizing, signaling and repairing DSBs within eukaryotic cells. The majority of biochemical and genetic studies have used simple, DNA substrates, whereas only recently efforts have been geared towards understanding how the repair machinery deals with DSBs within chromatin fibers, the nucleoprotein complex that packages DNA within the eukaryotic nucleus. The aim of this review is to discuss our recent understanding of the relationship between chromatin structure and the repair of DSBs by homologous recombination. In particular, we discuss recent studies implicating specialized roles for several, distinct ATP-dependent chromatin remodeling enzymes in facilitating multiple steps within the homologous recombination process.
Deep Sequencing in Microdissected Renal Tubules Identifies Nephron Segment–Specific Transcriptomes

The function of each renal tubule segment depends on the genes expressed therein. High-throughput methods used for global profiling of gene expression in unique cell types have shown low sensitivity and high false positivity, thereby limiting the usefulness of these methods in transcriptomic research. However, deep sequencing of RNA species (RNA-seq) achieves highly sensitive and quantitative transcriptomic profiling by sequencing RNAs in a massive, parallel manner. Here, we used RNA-seq coupled with classic renal tubule microdissection to comprehensively profile gene expression in each of 14 renal tubule segments from the proximal tubule through the inner medullary collecting duct of rat kidneys. Polyadenylated mRNAs were captured by oligo-dT primers and processed into adapter–ligated cDNA libraries that were sequenced using an Illumina platform. Transcriptomes were identified to a median depth of 8261 genes in microdissected renal tubule samples (105 replicates in total) and glomeruli (5 replicates). Manual microdissection allowed a high degree of sample purity, which was evidenced by the observed distributions of well established cell–specific markers. The main product of this work is an extensive database of gene expression along the nephron provided as a publicly accessible webpage (https://helixweb.nih.gov/ESBL/Database/NephronRNAseq/index.html). The data also provide genome-wide maps of alternative exon usage and polyadenylation sites in the kidney. We illustrate the use of the data by profiling transcription factor expression along the renal tubule and mapping metabolic pathways.
The Determination of Seamount Magnetism

Summary Using a technique due to Backus the average direction of magnetization of a seamount can be found from sea-surface magnetic observations without assuming anything about the internal structure of the body. Other advantages of this approach are that the required integrals can be made very simple without approximation and that uncertainties can be estimated.
Cyclic mechanical stretching of human tendon fibroblasts increases the production of prostaglandin E2 and levels of cyclooxygenase expression: a novel in vitro model study.

Prostaglandin E2 (PGE2) is a known inflammatory mediator of tendinitis, for which mechanical loading on tendons is believed to be one of the most prominent causation factors. Previous in vitro studies have shown that cyclic mechanical stretching of cells can cause changes in cell morphology and alteration of both DNA and protein syntheses. In our study, a novel system was used whereby tendon fibroblasts are cultured on microgrooved silicone surfaces and are subjected to cyclic uniaxial stretching along their long axes to mimic in vivo conditions. Using this unique model system, the cell shape and alignment can be controlled. Further, this study was designed to test the hypotheses that PGE2 production increases in a stretching magnitude-dependent manner and that cyclooxygenase (COX) is responsible for the increased PGE2 production in tendon fibroblasts. Human patellar tendon fibroblasts were cultured on the microgrooved silicone membranes and cyclically stretched at 4%, 8%, or 12% of nominal dish length for 24 hr. PGE2 production was found to be increased 1.7-fold at 8% cyclic stretching and 2.2-fold at 12% cyclic stretching compared with nonstretched controls. In addition, human tendon fibroblasts had increased expression of both COX-1 and COX-2 for all three applied stretching magnitudes, with the exception of COX-1 at 4% cyclic stretching. Also, cellular PGE2 production, after 8% cyclic stretching, was significantly decreased with the addition of indomethacin (25 µM), a COX competitive inhibitor, compared with stretched cells without indomethacin treatment. These findings suggest that the increase in PGE2 production by the human tendon fibroblasts is stretching magnitude-dependent, and that the increase in COX expression contributes to the increased production of PGE2 after cyclic stretching. As PGE2 is a known inflammatory mediator of tendinitis, the contribution of COX-1 and COX-2 to
Heart Failure Pharmacogenetics: Past, Present, and Future

Heart failure is an increasingly common disease associated with significant morbidity and mortality in the aging population. Recent advances in heart failure pharmacotherapy have established several agents as beneficial to disease progression and outcomes. However, current consensus guideline-recommended pharmacotherapy may not represent an optimal treatment strategy in all heart failure patients. Specifically, individuals with genetic variation in regions central to mediation of beneficial response to standard heart failure agents may not receive optimal benefit from these drugs. Additionally, targeted approaches in phase 3 clinical trials that select patients for inclusion based on the genotype most likely to respond might advance the currently stalled drug development pipeline in heart failure. This article reviews the literature in heart failure pharmacogenetics to date, opportunities for discovery in recent and upcoming clinical trials, as well as future directions in this field.
On the dynamic response of a prestressed beam

Abstract The dynamic bending response of a prestressed beam, in which the prestressing rod is continuously supported, is studied analytically and experimentally. It is found that a resultant axial prestressing force which passes through the centroids of the beam cross-section has no effect upon the bending response of the beam. For example, the natural frequencies are not affected by the magnitude of the prestressing force. Also, the pre-stressed beam is always stable, even for very large values of the prestressing force.
An approach to field screening potato genotypes for potato leaf roll virus resistance

Eight potato cultivars and two advanced breeder selections were assessed for field resistance to the potato leaf roll virus (PLRV) following field exposures in which PLRV-infected Russet Burbank plants were used as inoculum sources within treatments. This screening protocol provided consistent PLRV resistance ratings despite year-to-year variation in PLRV pressure. Secondary disease incidence based on enzyme-linked immunosorbent assay (ELISA) of foliage from tuber progeny ranged from 0–87% in 1990 and 0–67% in 1991, and was consistent with reported PLRV resistance ratings for eight of ten genotypes. Agreement between visual assessment and ELISA on plants from harvested tubers was 94% in 1990 and 83% in 1991, for all genotypes. However, agreement data were inconsistent from year-to-year, with the exception of three genotypes. In both years, current season infection, based on ELISA of foliage, was detected in less than two percent of the plants and, was inadequate as a measure of secondary PLRV incidence. Green peach aphid (GPA) populations did not differ among genotypes at sampling times during the season, but the PLRV concentration in GPA colonizing Russet Burbank plots was significantly higher than in GPA colonizing any other genotype.
TAF1 histone acetyltransferase activity in Sp1 activation of the cyclin D1 promoter.

A missense mutation within the histone acetyltransferase (HAT) domain of the TATA binding protein-associated factor TAF1 induces ts13 cells to undergo a late G1 arrest and decreases cyclin D1 transcription. We have found that TAF1 mutants (Δ844-850 and Δ848-850, from which amino acids 844 through 850 and 848 through 850 have been deleted, respectively) deficient in HAT activity are unable to complement the ts13 defect in cell proliferation and cyclin D1 transcription. Chromatin immunoprecipitation assays revealed that histone H3 acetylation was reduced at the cyclin D1 promoter but not the c-fos promoter upon inactivation of TAF1 in ts13 cells. The hypoacetylation of H3 at the cyclin D1 promoter was reversed by treatment with trichostatin A (TSA), a histone deacetylase inhibitor, or by expression of TAF1 proteins that retain HAT activity. Transcription of a chimeric promoter containing the Sp1 sites of cyclin D1 and c-fos core remained TAF1 dependent in ts13 cells. Treatment with TSA restored full activity to the cyclin D1-c-fos chimera at 39.5°C. In vivo genomic footprinting experiments indicate that protein-DNA interactions at the Sp1 sites of the cyclin D1 promoter were compromised at 39.5°C in ts13 cells. These data have led us to hypothesize that TAF1-dependent histone acetylation facilitates transcription factor binding to the Sp1 sites, thereby activating cyclin D1 transcription and ultimately G1-to-S-phase progression.
The molecular mechanisms responsible for resistance in plant–pathogen interactions of the gene-for-gene type function more broadly than previously imagined

Molecular biology is making it possible to identify both the genes and the gene products involved in infection and disease and then to direct control strategies at these genes and gene products. Understandably, the vast majority of this kind of research and development continues to be directed at human diseases, but some of the most remarkable advances and biggest surprises have come from studies of plant diseases. Of course, plants, not having a circulatory system and ability to make antibodies, depend on very different defense strategies than those used by animals. Plants with ability to resist infection by a particular pathogen are referred to as “resistant” to that pathogen, and pathogens lacking the ability to attack a particular plant are referred to as “avirulent” on that plant. Research begun shortly after the rediscovery of Mendel’s laws showed that resistance is heritable and plant breeders have been breeding varieties of crop plants with disease resistance ever since. Unfortunately for agriculture, the pathogen is adaptive by its ability to continually evolve strains that defeat the resistance genes deployed in crop plants by plant breeders. This has led to the treadmill of continually updating and replacing varieties with different genes or combinations of genes for resistance in response to the ever-changing …
The Managed Heart: Commercialization of Human Feeling

The article presents a review of the book “The Managed Heart: Commercialization of Human Feeling,” by Arlie Russell Hochschild.
Role of alterations in refractoriness and conduction in the genesis of reentrant arrhythmias. Implications for antiarrhythmic effects of class III drugs

Despite the fact that a number of different electrophysiologic mechanisms are capable of causing cardiac arrhythmias, reentrant excitation has emerged as the most important mechanism causing life-threatening arrhythmias that arise in the ventricles. Pharmacologic therapy of arrhythmias caused by reentry is aimed at preventing the conditions that either facilitate the initiation of the circulating reentrant excitation wave or the conditions that permit its persistence. This involves alterations in either refractoriness or conduction by the drugs. Both atrial and ventricular tachyarrhythmias may follow premature depolarizations that occur at a critical coupling interval to a previous excitation. One desirable property of antiarrhythmic drugs might be to prevent the initiation of reentrant excitation by the triggering premature impulse. Mechanisms are described to show how drugs that prolong the action potential duration (class III antiarrhythmic drugs) might have this effect. It is, however, emphasized that drug effects that have been documented in electrophysiologic studies on normal myocardium might not occur in an arrhythmogenic region that has pathologic alterations, because of changes in the properties of ion channels of the diseased myocardial cells. Antiarrhythmic drugs might also terminate ongoing reentrant excitation by causing block of conduction in the reentrant pathway, at least for one beat. Class III drugs are expected to stop the perpetuation of reentry by prolonging the action potential duration and the refractory period of myocardial fibers in the reentrant circuit to such an extent that the propagating reentrant impulse no longer finds excitable myocardium but blocks in refractory tissue. Therefore, the effectiveness of this drug class to terminate reentry should depend on at least 2 factors: the size of the excitable gap as the reentrant impulse moves around the circuit, which may be related to the mechanism that causes reentry, and the degree to which the drugs can prolong the action potential duration and refractory period at the rapid rates of tachycardia. Each of these factors is discussed with relation to the proposed mechanism of action of drugs that prolong repolarization.
Ceramide Conversion to Sphingosine-1-Phosphate is Essential for Survival in C3H10T1/2 Cells

Ceramide and sphingosine-1-phosphate (S1P) are important dietary lipids involved in cell growth, differentiation, apoptosis and cell survival. Treatment of C3H10T1/2 murine fibroblast cells (10T1/2) with ceramide did not induce apoptosis, a commonly observed effect of ceramide treatment. To determine whether the metabolism of ceramide played a role in this resistance to apoptosis, inhibitors of ceramidase and sphingosine kinase, two important enzymes in sphingolipid metabolism, were used. Treatment of 10T1/2 cells both without or with ceramide plus N-oleoyl-ethanolamine (NOE) and (1S,2R)-D-erythro-s-(N-myristoylamino)-1-phenol-1-propanol (MAPP), two ceramidase inhibitors, resulted in fourfold and eightfold increases, respectively, in apoptosis. Cells treated without or with ceramide plus N,N-dimethylsphingosine (DMS), a potent sphingosine kinase inhibitor, resulted in fourfold and sixfold increases, respectively, in apoptosis. In all treatments the induction of apoptosis was prevented by the addition of S1P. With the addition of S1P with NOE and MAPP as well as with ceramide, treatments reduced the apoptotic response by 30 and 35%, respectively; whereas the addition of S1P with the DMS only and ceramide with DMS treatments reduced the apoptotic response by 60 and 70%, respectively. Studies using labeled ceramide demonstrated ceramide was metabolized to S1P. In addition, a 14-fold increase in apoptosis occurred in cells treated with a nonhydrolyzable analog of ceramide, ceramine, compared with vehicle control. Because inhibiting the conversion of ceramide to S1P resulted in apoptosis, the lack of an apoptotic response to ceramide alone for C3H10T1/2 cells is attributable to the conversion of this pro-apoptotic sphingolipid to the anti-apoptotic metabolite S1P, which is essential for cell survival.
Open-celled polymeric foam monoliths for heavy metal separations study

Open-celled polymeric foam monoliths prepared by high internal phase emulsion polymerization (HIPE) are being investigated as improved materials for separation of heavy metals. In column flow studies, the foam monoliths have high flow rates and are durable up to at least 40 psi. A 4-vinylpyridine functionality has been incorporated into vinylbenzylchloride/styrene copolymer foams by graft-polymerization of vinylpyridine. The open structure of the foam and the flexible graft-polymerized ion-exchange chains result in improved kinetics in metal uptake. Iron uptake kinetics were greatly increased in the grafted foams over resin beads of similar structure. Plutonium uptake kinetics were moderately increased in the foams.