cssi/SciSciGPT-SciSciNet huggingface dataset:
Physical Models for Early Membrane Growth and Evolution

Lipid membranes are a ubiquitous structure in biology and would have been an essential component of the first cells. In the absence of evolved cellular machinery, early membranes had to be capable of growth, division, and solute transport by intrinsic physical processes. We have used a combination of spectroscopic and physical methods to characterize the phase properties of fatty acids and related single-chain lipids, which have been proposed to serve a role as primitive membrane lipids. We found that low concentration vesicle solution feature significant amounts of coexisting micelles, while high concentration solutions were predominantly lamellar (vesicles). This concentration-dependent equilibrium allowed us to drive the growth of pre-existing vesicles by gentle solution evaporation, which raises the lipid concentration thus favoring lamellar incorporation. This phenomenon could have provided a mechanism for early cell membrane growth driven entirely by environmental fluctuations.We have also characterized a very different growth mechanism that relies on the inter-vesicle exchange of monomers, which occurs rapidly for single chain lipids. Small amounts of double-chain lipids, such as phospholipids, drive the growth of fatty acid vesicles and the concurrent shrinkage of neighboring vesicles with fewer or no phospholipids. This phenomenon would have provided a direct selective advantage of the adoption of phospholipid-based membranes, a critical step in early cellular evolution. We have found that such a putative transition in lipid composition is accompanied by changes in the physical properties of the membrane, most notably a decrease in membrane fluidity and permeability. These findings support a model in which early cell membranes, composed of single-chain lipids, had the intrinsic permeability to allow for passive solute transport. The subsequent evolution of less permeable, phospholipid membranes would have then allowed for the adoption of protein-based transport machinery and internalized metabolite synthesis.
Mechanics of intraply hybrid composites—properties, analysis, and design

A mechanics theory is developed for predicting the physical thermal, hygral and mechanical properties (including various strengths) of unidirectional intraply hybrid composites (UIHC) based on unidirectional properties of the constituent composites. Procedures are described which can use this theory in conjunction with composite mechanics computer codes and general purpose structural analysis finite element programs for the analysis/design of structural components made from intraply hybrid angleplied laminates (IHAL). Comparisons with limited data show that this theory predicts mechanical properties of UIHC and flexural stiffnesses of IHAL which are in good agreement with experimental data. The theory developed herein makes it possible to design and optimize structural components from IHAL based on a large class of available constituent fibers.
Modern problems of low-velocity stopping powers

Abstract Low velocity stopping powers pertain to regimes in electron plasmas of all degeneracies where the projectile velocities are less than the mean electron velocities in the medium. This field is now in a new phase of rapid development. Solutions to three basic problems are presented here. (1) The material dependence of stopping powers is traced to variations of the mean valence-electron densities in the periodic system. (2) The validity of effective charge theory is demonstrated in linear-response approximation. Effective charge is found to increase, for a given ionic charge, with the atomic number of the projectile. This theory permits distinct predictions that agree with experiment. (3) Extensions to hot plasmas of interest in fusion suggest the possibility of measuring the electron temperature of plasmas under the working conditions of controlled thermonuclear reactors by ion-beam analysis.
Electron transfer between He-like ions and He

Single- and double-electron-transfer cross sections have been measured for B/sup 3 +/, C/sup 4 +/, N/sup 5 +/, and O/sup 6 +/ in collision with He at velocities between 0.5 and 1.2 x 10/sup 8/ cm/sec. The single-electron-capture cross sections peak near 15 x 10/sup -16/ cm/sup 2/ for each case except C/sup 4 +/,where single capture is anomalously low. The double-capture cross sections are about 3 x 10/sup -16/ cm/sup 2/, except for B/sup 3 +/, where the highest observed value is 1.5 x 10/sup -16/ cm/sup 2/. These measurements for B/sup 3 +/ and C/sup 4 +/ compare well with existing experiments and theory, except for C/sup 4 +/ single capture. Within the narrow range tested, C/sup 4 +/ and B/sup 3 +/ cross sections exhibit variation with velocity, but N/sup 5 +/ and O/sup 6 +/ cross sections remain constant.
Organization, management and operation of contemporary academic mass spectrometry service facilities

The rapid evolution of mass spectrometry in the past 15 years has moved mass spectrometry facilities from the traditional model in which instruments were located in and used for a single department's samples to a distributed model servicing entire universities. In this paper we describe two such shared instrument facilities that have evolved from a base in a single department to facilities that service a broad clientele. The Purdue University Campus-wide Mass Spectrometry Center (CWMSC) is a decentralized facility with multiple sites on campus. The CWMSC is a limited-access facility in which samples are run by service facility personnel in close cooperation with investigators. The Vanderbilt University Mass Spectrometry Research Center (VU-MSRC) is a centralized facility in the medical school that provides services to the university at large. The VU-MSRC is an open-access facility in which users are expected to prepare and analyze their own samples under the guidance of a trained operator. Perhaps the most significant benefit achieved by these models has been the minimization of academic barriers and the resultant intellectual cross-fertilization that has greatly enriched research at institutions where this approach has been adopted. The advantages and limitations of both models are discussed in terms of the traditional academic paradigm of service, research and education.
The discovery of the vitamins

The discovery of the vitamins was a major scientific achievement in our understanding of health and disease. In 1912, Casimir Funk originally coined the term "vitamine". The major period of discovery began in the early nineteenth century and ended at the mid-twentieth century. The puzzle of each vitamin was solved through the work and contributions of epidemiologists, physicians, physiologists, and chemists. Rather than a mythical story of crowning scientific breakthroughs, the reality was a slow, stepwise progress that included setbacks, contradictions, refutations, and some chicanery. Research on the vitamins that are related to major deficiency syndromes began when the germ theory of disease was dominant and dogma held that only four nutritional factors were essential: proteins, carbohydrates, fats, and minerals. Clinicians soon recognized scurvy, beriberi, rickets, pellagra, and xerophthalmia as specific vitamin deficiencies, rather than diseases due to infections or toxins. Experimental physiology with animal models played a fundamental role in nutrition research and greatly shortened the period of human suffering from vitamin deficiencies. Ultimately it was the chemists who isolated the various vitamins, deduced their chemical structure, and developed methods for synthesis of vitamins. Our understanding of the vitamins continues to evolve from the initial period of discovery.
A Randomized Controlled Trial Evaluating a Manualized TeleCoaching Protocol for Improving Adherence to a Web-Based Intervention for the Treatment of Depression

Background: Web-based interventions for depression that are supported by coaching have generally produced larger effect-sizes, relative to standalone web-based interventions. This is likely due to the effect of coaching on adherence. We evaluated the efficacy of a manualized telephone coaching intervention (TeleCoach) aimed at improving adherence to a web-based intervention (moodManager), as well as the relationship between adherence and depressive symptom outcomes. Methods: 101 patients with MDD, recruited from primary care, were randomized to 12 weeks moodManager+TeleCoach, 12 weeks of self-directed moodManager, or 6 weeks of a waitlist control (WLC). Depressive symptom severity was measured using the PHQ-9. Results: TeleCoach+moodManager, compared to self-directed moodManager, resulted in significantly greater numbers of login days (p=0.01), greater time until last use (p=0.007), greater use of lessons (p=0.03), greater variety of interactive tools used (p=0.02), but total instances of tool use did not reach statistical significance. (p=0.07). TeleCoach+moodManager produced significantly lower PHQ-9 scores relative to WLC at week 6 (p=0.04), but there were no other significant differences in PHQ-9 scores at weeks 6 or 12 (ps.0.20) across treatment arms. Baseline PHQ-9 scores were no significantly related to adherence to moodManager. Conclusions: TeleCoach produced significantly greater adherence to moodManager, relative to self-directed moodManager. TeleCoached moodManager produced greater reductions in depressive symptoms relative to WLC, however, there were no statistically significant differences relative to self-directed moodManager. While greater use was associated with better outcomes, most users in both TeleCoach and self-directed moodManager had dropped out of treatment by week 12. Even with telephone coaching, adherence to web-based interventions for depression remains a challenge. Methods of improving coaching models are discussed. Trial Registration: Clinicaltrials.gov NCT00719979
Delivering Care to Injection Drug Users Coinfected with HIV and Hepatitis C Virus

Injection drug use has fueled the epidemic of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) coinfection in the United States. Nevertheless, drug dependence is among the main reasons that coinfected persons are not being treated for HCV infection. This report describes the development and progress of an HIV clinic program (funded by the Ryan White Comprehensive AIDS Resources Emergency Act) to deliver care for HCV infection to HIV-seropositive injection drug users. To optimize safety and adherence, pegylated interferon is directly administered to patients in the context of integrated addiction, psychiatric, and HIV and HCV therapy. Ribavirin is packed weekly in pill boxes for patients to take at home. Thus far, adherence to weekly visits for treatment with interferon has been 99%. No one has had to stop treatment for HCV infection because of ongoing drug use, addiction relapse or exacerbation, or psychiatric complications. Presented here is a work in progress, rather than a finished research project or definitive model of care.
Effect of sequential treatments with alendronate, parathyroid hormone (1–34) and raloxifene on cortical bone mass and strength in ovariectomized rats

Abstract Anti-resorptive and anabolic agents are often prescribed for the treatment of osteoporosis continuously or sequentially for many years. However their impact on cortical bone quality and bone strength is not clear. Methods Six-month old female rats were either sham operated or ovariectomized (OVX). OVX rats were left untreated for two months and then were treated with vehicle (Veh), hPTH (1–34) (PTH), alendronate (Aln), or raloxifene (Ral) sequentially for three month intervals, for a total of three periods. Mid-tibial cortical bone architecture, mass, mineralization, and strength were measured on necropsy samples obtained after each period. Bone indentation properties were measured on proximal femur necropsy samples. Results Eight or more months of estrogen deficiency in rats resulted in decreased cortical bone area and thickness. Treatment with PTH for 3 months caused the deposition of endocortical lamellar bone that increased cortical bone area, thickness, and strength. These improvements were lost when PTH was withdrawn without followup treatment, but were maintained for the maximum times tested, six months with Ral and three months with Aln. Pre-treatment with anti-resorptives was also somewhat successful in ultimately preserving the additional endocortical lamellar bone formed under PTH treatment. These treatments did not affect bone indentation properties. Summary Sequential therapy that involved both PTH and anti-resorptive agents was required to achieve lasting improvements in cortical area, thickness, and strength in OVX rats. Anti-resorptive therapy, either prior to or following PTH, was required to preserve gains attributable to an anabolic agent.
Medical Care of Nursing Home Residents

Objective To present an overview of the special challenges of providing medical care for nursing home residents. Design After researching the current medical literature, we summarized information on nursing home demographics, government regulations, and specific care issues for medical practice in nursing homes. Results Almost 2 million Americans currently live in more than 20,000 nursing homes nationwide, and these nursing home residents are increasingly older and more frail than in the past. Most nursing home residents receive multiple prescription medications, and many are cognitively and functionally impaired. Nursing home-acquired infections are a frequent occurrence, as are falls and fall-related injuries. Recent federal laws have had a major effect on medical care in the nursing home and have made physicians more accountable for the care provided. The use of physical restraints and psychotropic drugs has been severely restricted. Conclusion The medical care of nursing home residents presents many challenges to primary-care physicians. Nevertheless, nursing home residents are among those patients in greatest need of competent, compassionate care. Despite numerous disincentives, provision of medical care for nursing home residents can be gratifying.
Teaching Point-Group Symmetry with Three-Dimensional Models.

Three tools for teaching symmetry in the context of an upper-level undergraduate or introductory graduate course on the chemical applications of group theory are presented. The first is a collection of objects that have the symmetries of all the low-symmetry and high-symmetry point groups and the point groups with rotational symmetries from 2-fold to 6-fold. Students can sort the objects by point group and can also see similarities and differences between point groups. The second is a magnet-backed mirror onto which are placed molecular models that have been modified to rest on the mirror and represent atoms and bonds that are on the mirror plane. The third is a frame to show the perpendicular C2 axes that are a feature of all the Dnh, Dnd, and Dn point groups.
Ethanol dependence and withdrawal selectively alter localized cerebral glucose utilization.

Abstract The 2-deoxyglucose technique was used to determine local cerebral glucose utilization (LCGU) in over 50 brain regions of rats physically dependent upon ethanol and compared to those of acutely intoxicated and those undergoing an overt ethanol-withdrawal syndrome. Dependent-intoxicated rats (average 3lood ethanol concentration 64 mM) had decreased LCGU in 13/54 regions, including those associated with the limbic system, cerebellum, and motor system. The ethanol withdrawal syndrome was associated with 17/50 gray regions showing an increase, including regions involved with motor function, auditory system, and mammillary bodies-anterior thalamus-cingulate cortex pathway. The most pronounced differences between these groups occurred in regions associated with motor function, cerebellar function, anterior thalamus, and median raphe. Comparisons between dependent-intoxicated and acutely intoxicated rats (average blood ethanol concentration 66 mM) revealed that acute intoxication was associated with a relatively greater reduction in LCGU in regions involved with sensory-related functions, mammillary bodies, and median raphe. With the development of dependence, adaptation occurred in these regions except for inferior colliculus and median raphe. Dependence was also associated with a relative decrease in LCGU in white matter, limbic system, and extrapyramidal motor system.
Fluorescent labeling of the carbohydrate moieties of human chorionic gonadotropin and α1-acid glycoprotein

Abstract A method for covalent attachment of a fluorescent molecule to the carbohydrate moieties of glycoproteins is described. The glycoproteins were oxidized with periodate under mild conditions selective for sialic acid (Van Lenten, L. and Ashwell, G. (1971) J. Biol. Chem. 246, 1889–1894). The resulting aldehydes were condensed with either dansylhydrazine, dansylethylenediamine, or fluoresceinamine followed by reduction with NaCNBH3 and NaBH4. Conjugates prepared with dansylhydrazine were found to be insufficiently stable for spectroscopic analysis, whereas the primary amines produced stable conjugates whose fluorescence polarization ( P ) was constant for several hours at 37°C. The degree of labeling correlated roughly with the sialic acid contents of the vaious glycoproteins. Very little covalent incorporation was observed with albumin (which is devoid of carbohydrate) or with asialo α 1 - acid glycoprotein. Exclusion chromatography in the presence of a dissociating agent was sometimes required to remove significant amounts of noncovalently adsorbed dye. Fluorescent-labeled α subunits of human chorionic gonadotropin were shown to recombine normally with native β subunits. However, the labeling procedure appeared to compromise the ability of the β subunits to recombine. Electrophoretic analysis produced evidence of covalent cross-linking between subunits following periodate oxidation of the intact gonadotropin. The possibility that primary amine groups of the protein compete with added fluorescent amines for reaction with periodate-generated aldehydes is discussed.
Mindfulness-based stress reduction for parents of young children with developmental delays: implications for parental mental health and child behavior problems.

Background Parents of children with developmental delays (DD) typically report elevated levels of parental stress compared with parents of typically developing children. Children with DD are also at high risk for exhibiting significant behaviour problems. Parental stress has been shown to impact the development of these behaviour problems; however, it is rarely addressed in interventions aimed at reducing child behaviour problems. The current study examined the efficacy of mindfulness-based stress reduction (MBSR) for parents of children with DD by investigating whether this intervention is effective in reducing parenting stress and whether decreases in parenting stress lead to reductions in behaviour problems among children with DD. Materials and methods Forty six parents of children with DD were randomly assigned to an immediate treatment or wait list-control group. Participants completed questionnaires assessing parental stress and child behaviour problems at intake and at a second assessment, which took place after only the immediate treatment group had received the MBSR. Results Parents who participated in MBSR reported significantly less stress and depression as well as greater life satisfaction compared with wait list-control parents. Regarding child outcomes, children whose parents participated in MBSR were reported to have fewer behaviour problems following the intervention, specifically in the areas of attention problems and ADHD symptomatology. Discussion Results indicated that MBSR may be an effective intervention for ameliorating parental stress and mental health problems among parents of children with DD. Additionally, these benefits may 'spill over' and improve behaviour challenges among these children.
High-throughput electron-beam lithography

A new approach for fabricating arrays of electron beam columns by stacking silicon wafers with micron accuracy has been developed. This approach combines the precision of semiconductor processing and fiber optic technologies. A (100) silicon wafer is anisotropically etched to create an array of apertures on the top or bottom of the wafer and four orthogonal v- grooves on both surfaces of the wafer. Precision pyrex fibers align and bond the v-grooves on the top of one wafer to the bottom of the next wafer. This procedure is repeated to create thick structures and a stack of six wafers is used to create arrays of scanning electron microscopes (SEMs). This technique is suitable for fabricating 1 - 30 mm long electron optical columns. The optimum size is determined by the desired array size, operating voltage, resolution, field of view, and working distance. The first wafer contains an array of micromachined field emission electron sources. The next three wafers accelerate and focus the electron beams. The last two wafers in the stack have electrodes to deflect each beam and correct for astigmatism. The performance of an SEM improves as its length is reduced and a subcm 2 keV SEM with a field emission source should have approximately 7 nm resolution.
On rate-independent continuum theories of graphite and their experimental verification

Abstract Uniaxial tension-compression tests with artificial graphites have shown that in the temperature range from 75°F to 750°F these materials exhibit essentially rate-independent elastoplastic behavior. Consequently, a rate-independent continuum theory of graphite is appropriate for representation of the behavior of these materials within the temperature range indicated above. These experiments have also shown that the stress-strain curves are nonlinear even at low stress levels for loading, unloading and reloading. It follows that a region of purely linear response is either very small or nonexistent even during unloading and reloading. The classical theory of plasticity must therefore be modified to become applicable to the mechanical behavior of artificial graphites. This paper discusses the development of two variations of a continuum theory of artificial graphite, which are based on a generalization of the classical theory of plasticity, and it proposes proper experiments to verify them.
Are in vitro fertilization pregnancies with early spontaneous reduction high risk

Objective The objective of the study was to determine whether spontaneous reduction in in vitro fertilization pregnancies results in outcomes comparable with in vitro fertilization singleton pregnancies or ongoing twin pregnancies. Study design Women with in vitro fertilization pregnancies from 2003 to 2005 who had first-trimester ultrasound and delivered in our hospital were identified. Those with documented reduction from dichorionic twins to a single viable fetus at 14 weeks or less were categorized as spontaneous reduction pregnancies and were compared with dichorionic twin and singleton pregnancies without reduction. Results One hundred sixty-eight singleton, 55 spontaneous reduction, and 86 twin pregnancies were included. Gestational age at delivery was similar in the singleton and spontaneous reduction groups; twins delivered significantly earlier. Spontaneous reduction was associated with lower birth weight than other singleton pregnancies (median 3062 g versus 3425 g; P = .005). The rate of pre-eclampsia was higher in pregnancies with spontaneous reduction, compared with other singleton pregnancies 9.3% versus 2.4%; P = .04). Conclusion Spontaneous reduction of a twin to a singleton pregnancy is associated with prolonged gestation and higher birth weight for the remaining fetus.
Improving the rate of convergence of high-order finite elements on polyhedra II: Mesh refinements and interpolation

We construct a sequence of meshes  k ′ that provides quasi-optimal rates of convergence for the solution of the Poisson equation on a bounded polyhedral domain with right-hand side in H m−1, m ≥ 2. More precisely, let Ω ⊂ ℝ3 be a bounded polyhedral domain and let u ∊ H 1(Ω) be the solution of the Poisson problem − Δ u = f ∊ H m−1(Ω), m ≥ 2, u = 0 on ∂ Ω. Also, let S k be the finite element space of continuous, piecewise polynomials of degree m ≥ 2 on  k ′ and let u k ∊ S k be the finite element approximation of u, then ‖u − u k ‖ H 1(Ω) ≤ C dim(S k )−m/3 ‖f‖ H m−1(Ω), with C independent of k and f. Our method relies on the a priori estimate ‖u‖ ≤ C ‖f‖ H m−1(Ω) in certain anisotropic weighted Sobolev spaces , with a > 0 small, determined only by Ω. The weight is the distance to the set of singular boundary points (i.e., edges). The main feature of our mesh refinement is that a segment AB in  k ′ will be divided into two segments AC and CB in  k+1′ as follows: |AC| = |CB| if A and B are equally singu...
Effects of a pH electrode across the lower esophageal sphincter.

Recent studies have suggested that combined monitoring of the esophagus and stomach for prolonged periods may be the best method for investigating patients with upper gastrointestinal complaints. However, the effects of an electrode across the LES on esophageal reflux parameters have not been extensively studied. We studied 10 healthy volunteers and 10 patients with GERD twice with 24-hr pH monitoring. In phase 1, two glass electrodes were placed 1 cm below the UES and 5 cm above the LES. One week later in phase 2, patients were restudied with one electrode 5 cm above and one 5 cm below the LES. Although total acid exposure remained the same in healthy volunteers, three volunteers who spontaneously refluxed at night had abnormal prolongation of their supine acid exposure during phase 2 of the study. In patients with GERD, the electrode across the LES resulted in significant (P=0.01) increase in supine acid exposure and showed a strong tendency for the number of reflux episodes >5 min supine (P=0.02) and longest reflux episode supine (P=0.06) to increase without a change in the number of reflux episodes. In conclusion, a small glass electrode across the LES results in prolongation of supine acid exposure in both healthy volunteers spontaneously refluxing at night and the majority of patients with GERD. This results from the electrode interfering with clearance of refluxed acid in the supine position. Thus, combined esophageal and gastric pH monitoring may have important limitations in investigating gastroesophageal symptoms.
Lower-Defect Graphene Oxide Nanoribbons from Multiwalled Carbon Nanotubes

An improved method is described for the production of graphene oxide nanoribbons (GONRs) via longitudinal unzipping of multiwalled carbon nanotubes. The method produces GONRs with fewer defects and/or holes on the basal plane, maintains narrow ribbons <100 nm wide, and maximizes the high aspect ratio. Changes in the reaction conditions such as acid content, time, and temperature were investigated. The new, optimized method which introduces a second, weaker acid into the system, improves the selectivity of the oxidative unzipping presumably by in situ protection of the vicinal diols formed on the basal plane of graphene during the oxidation, and thereby prevents their overoxidation and subsequent hole generation. The optimized GONRs exhibit increased electrical conductivity over those chemically reduced nanoribbons produced by previously reported procedures.
Behavior of Salmonella typhimurium DT104 during the manufacture and storage of pepperoni

Abstract Pepperoni batter (ca. 70% pork:30% beef) was prepared and subsequently inoculated with a six-strain cocktail (ca. 4.4×10 7 per gram batter) of Salmonella typhimurium DT104. After fermentation at 36°C and 92% relative humidity (RH) to ≤pH 4.8, counts of the pathogen decreased by about 1.3 log 10 units. An additional 1.6 log 10 unit decrease was observed following drying at 13°C and 65% RH to a moisture protein ratio (M/Pr) of 1.6:1. After storage of pepperoni sticks for 56 days under vacuum at 4 or 21°C, counts of the pathogen were about 4.6 and 6.6 log 10 units lower, respectively, compared with starting levels in the batter. These data establish that fermentation and drying result in about a 3.0 log 10 reduction in numbers of S typhimurium DT104 in pepperoni sticks and that storage of pepperoni sticks under vacuum at ambient temperature is more severe on the pathogen than refrigerated storage.
We are not alone: A sample of international policy challenges and issues

Abstract International trade in information technology involves political, economic, and military factors that are highly interrelated, making U.S. policy formulation a complex process which requires extensive data on foreign and domestic policies and technological capabilities. An analysis of U.S. policy for controlling the reexport of high‐technology goods provides an example of this interdependence. Four primary points are emphasized throughout the paper: (1) there seems to be only limited appreciation of how different issues get entangled in the international arena; (2) the data on which to base policy decisions regarding information technology do not exist in a readily available and usable form; (3) there is little understanding of the technological status and policy support for information technology in other countries; and (4) the people needed to analyze international developments and policies in the information technologies are not being trained.
Origin of Lau Basin Rise sediment

Abstract The chemistry and mineralogy of sediments in the vicinity of the active rise in the Lau Basin can be accounted for by weathering of tholeiitic basalts exposed in the Basin, the introduction of pumice fragments derived from the Tonga Ridge, precipitation of ferromanganese minerals from sea water and pore water addition.
Communication between homologous chromosomes: genetic alterations at a nuclease-hypersensitive site can alter mitotic chromatin structure at that site both in cis and in trans

Background: In vegetatively growing diploid strains of the yeast Saccharomyces cerevisiae, homologous chromosomes appear to be paired via multiple interstitial interactions, likely as a regular feature of the diploid lifestyle. We have previously suggested that this pairing is guided by direct physical interactions between intact DNA duplexes in nuclease-hypersensitive regions and that homology is sensed directly at the DNA level. Results: As a first test of this idea we have examined the level of DNase I sensitivity at a prominent nuclease-hypersensitive site in mitotic chromatin in strains that are either homozygous or heterozygous for a pair of alleles at this site. We find that the degree of nuclease sensitivity at this site on a given (maternal or paternal) chromosome can vary depending upon whether the homologue carries the same allele or the different allele. The data are suggestive that nuclease sensitivity is higher in the former case than in the latter, as though nuclease hypersensitivity might be increased when the two alleles match as compared to when they do not. Conclusions: Formally, these observations suggest that homologous chromosomes can communicate via a mechanism that senses the status of the assayed nuclease-hypersensitive site with resultant changes in chromatin structure at that site. The observed pattern of effects is fully compatible with direct physical interactions between homologues at nuclease-hypersensitive regions, but alternative scenarios also can be envisioned. Since DNase I hypersensitive sites occur in many important regions of chromosomes, homology-dependent interactions involving such regions could potentially affect diverse processes including gene expression (e.g. transvection), chromosome organization, domain structure, and/or DNA replication patterns.
The Effect of Custom-Made Braces for the Ankle and Hindfoot on Ankle and Foot Kinematics and Ground Reaction Forces

Abstract Kitaoka HB, Crevoisier XM, Harbst K, Hansen D, Kotajarvi B, Kaufman K. The effect of custom-made braces for the ankle and hindfoot on ankle and foot kinematics and ground reaction forces. Objective To assess the effects on gait of custom-made polypropylene orthoses: ankle-foot orthosis (AFO), rigid hindfoot orthosis (HFO-R), and articulated hindfoot orthosis (HFO-A). Design Experimental assessment. Setting Institutional practice, motion analysis laboratory. Participants Twenty asymptomatic normative subjects. Interventions Not applicable. Main Outcome Measures Three-dimensional kinematics, ground reaction force, and time-related factors in 4 conditions: shoe only, and shod with the AFO, HFO-R, and HFO-A. Results The AFO and HFO-R limited sagittal and coronal plane ankle-hindfoot motion. The HFO-A limited hindfoot coronal motion while allowing normal sagittal motion. At the midfoot, the AFO and HFO-A limited transverse motion, but the HFO-A also limited sagittal and coronal motion. Use of the HFO-R resulted in exaggerated midfoot sagittal and coronal motion. Braces that limited motion to a greater degree were associated with more atypical kinetic variables, indicative of less dynamic gait. The HFO-A resulted in ground reaction forces most similar to unbraced conditions. Conclusions Alteration in gait was affected by orthosis design. Orthoses with a rigid component crossing a joint restricted motion at that joint, but potentially compromised typical gait kinetic factors. For immobilizing the hindfoot, the HFO-A may be more comfortable and still provide more stability than the HFO-R or AFO.
Association between arsenic exposure from drinking water and hematuria: results from the Health Effects of Arsenic Longitudinal Study.

Arsenic (As) exposure has been associated with both urologic malignancy and renal dysfunction; however, its association with hematuria is unknown. We evaluated the association between drinking water As exposure and hematuria in 7843 men enrolled in the Health Effects of Arsenic Longitudinal Study (HEALS). Cross-sectional analysis of baseline data was conducted with As exposure assessed in both well water and urinary As measurements, while hematuria was measured using urine dipstick. Prospective analyses with Cox proportional regression models were based on urinary As and dipstick measurements obtained biannually since baseline up to six years. At baseline, urinary As was significantly related to prevalence of hematuria (P-trend 47.49 μg/l and 10.87 to 47.49 μg/l since last visit, respectively, and 1.17 (95% CI: 0.94-1.45) and 1.36 (95% CI: 1.10-1.66) for those with between-visit increases of 10.40 to 41.17 μg/l and >41.17 μg/l, respectively. These data indicate a positive association of As exposure with both prevalence and incidence of dipstick hematuria. This exposure effect appears modifiable by relatively short-term changes in drinking water As.
Glycocalyx of Agmenellum quadruplicatum

The marine cyanobacterium Agmenellum quadruplicatum was shown to possess an extracellular glycocalyx similar in structure to those surrounding other bacteria from a variety of natural environments. Thin sections of cells stained with ruthenium red and frozen-etched preparations of unfixed cells indicated the glycocalyx was a network of small fibrils. The glycocalyx was present during all phases of growth, and was not degraded during nutrient limitation.
Esophageal resection for recurrent achalasia

Background. This study examined esophageal resection as treatment for recurrence or treatment complications of achalasia. Methods. From 1976 through 1992, 37 patients (20 men and 17 women) underwent esophageal resection after initial surgical treatment for achalasia. The median age was 56 years (range, 19 to 84 years). Initial surgical treatment consisted of modified Heller myotomy in 28 patients, combined myotomy and antireflux procedure in 6, and antireflux procedure alone in 3. Twenty-six patients required an additional surgical procedure before esophageal resection (70.3%). Indication for esophageal resection was obstructive symptoms in 30 patients, cancer in 3, bleeding in 2, and perforation during dilation in 2. Reconstruction was established with the stomach in 26 patients, colon in 6, and small bowel in 5. Anastomosis was at the cervical level in 20 patients (54.1%) and intrathoracic in 17 (45.9%). Results. There were two operative deaths (5.4%), both caused by intraoperative hemorrhage during transhiatal resection. Twelve patients (32.4%) had complications, which included cardiac dysrhythmia in 3, cervical anastomotic leak in 2, transient vocal cord paralysis in 2, pneumonia in 2, pulmonary embolus in 2, and reexploration for bleeding in 1. Follow-up was complete in all patients and ranged from 1.4 to 16 years (median, 6.3 years). Excellent or good long-term functional results were present in 32 patients (91.4%). Conclusions. Esophageal resection provides reasonable long-term functional results in patients with recurrence or treatment complications of achalasia. In our experience, transhiatal resection is associated with increased morbidity and mortality.
The Political Economy of Gordon Tullock

It is fair to say that few public choice scholars have contributed to so many areas of public choice research as frequently or with as much insight as Gordon Tullock. Professor Tullock's work considers not only political and contractual relationships within a well-established legal order, but also extraordinary political behavior within rent-seeking societies, within firms, at court, within communities at war, among those considering revolution, and among those emerging from or falling into anarchy. The result is an unusually complete political economy that includes theories of the origin of the state; theories of decision making within bureaucracy, dictatorship, democracy, and the courts; and within science itself. It is also fair to say that Professor Tullock uses relatively simple tools to analyze these far-reaching topics. Indeed, it is the use of relatively simple tools that makes the broad scope of his work possible. All the principal actors in Tullock's analysis maximize expected net benefits in circumstances where * The perspective on Tullock's work presented here is based partly on his prolific writings and partly on numerous conversations with him over the course of several decades. He was kind enough to read through a previous draft, and the version presented here reflects his comments and suggestions. Comments and suggestions received at the 2002 meeting of the Public Choice Society, and from James Buchanan, Charles Rowley, Robert Tollison, and an
Crimes of War

Crimes of War Nick Turse, Kill Anything That Moves: The Real American War in Vietnam. New York: Metropolitan Books, 2013. 370 pp. Reviewed by David Hunt (University of Massachusetts, Boston) and Ma...
Measuring conceptual understanding: a case study

IT Educators are challenged with the task of providing learning experiences that helps learners build abstract mental models of IT concepts to help solve the complex, ill-defined problems they will face. But of the many instructional strategies discussed in the literature how can we tell which methods are better for the different types of IT knowledge presented. Can we assess how well different instructional strategies affect student's conceptual understanding of IT concepts? This descriptive study examined one possible way of measuring conceptual understanding of a specific learning activity called Model Eliciting Activates (MEAs).
Development of Occlusive Neointimal Lesions in Distal Pulmonary Arteries of Endothelin B Receptor–Deficient Rats: A New Model of Severe Pulmonary Arterial Hypertension

Background— Human pulmonary arterial hypertension (PAH) is characterized by proliferation of vascular smooth muscle and, in its more severe form, by the development of occlusive neointimal lesions. However, few animal models of pulmonary neointimal proliferation exist, thereby limiting a complete understanding of the pathobiology of PAH. Recent studies of the endothelin (ET) system demonstrate that deficiency of the ETB receptor predisposes adult rats to acute and chronic hypoxic PAH, yet these animals fail to develop neointimal lesions. Herein, we determined and thereafter showed that exposure of ETB receptor–deficient rats to the endothelial toxin monocrotaline (MCT) leads to the development of neointimal lesions that share hallmarks of human PAH. Methods and Results— The pulmonary hemodynamic and morphometric effects of 60 mg/kg MCT in control (MCT+/+) and ETB receptor–deficient (MCTsl/sl) rats at 6 weeks of age were assessed. MCTsl/sl rats developed more severe PAH, characterized by elevated pulmonary...
Plant size and spatial pattern in a natural population of Myosotis micrantha

We examined spatial distributions and plant sizes along a transect through a natural population of a winter annual, Myosotis micrantha. A size hierarchy existed, as indi- cated by high values of Gini coefficients of inequality for plant mass and correlated measures. Plants with no immediate conspecific neighbors were larger than plants with one or more near neighbors, suggesting that competition from near neighbors depressed plant size. However, there was strong positive spatial autocorrelation in plant size: large plants were associated with large neighbors and small ones with small neighbors. Plant size was also positively correlated with the combined biomass of near neighbors. The population formed a two-phase mosaic of patches of relatively large plants alter- nating with patches of smaller plants. The data suggest that individual plants compete with conspecifics, but the effects of competition are symmetrical. The most likely explanations for this spatially structured size hierarchy are variation in plant density, patchy distribution of resources, or a combination of the two.
Prairie Network fireballs: Data on height, distance and brightness for each measured time‐mar

— This paper presents data on distance along the trajectory, height and brightness (DTHM-values) at each measured point (i.e., at each time-mark) for Prairie Network fireballs photographed between 1963 and 1973. although dthm-values are not printed here in the “classical” manner as an extensive table, the electronic version of the catalogue belongs to this manuscript as its most substantial part and is accessible from the ftp-server sunkl.ASU.CAS.CZ (public domain) via anonymous login and under the directory pub in the file pnsao.dat.
Ethics and Strategy Innovation at Citigroup

The financial services sector is traditionally known for its focus on quick profits of “making the numbers,” but industry leaders are now waking up to the need for an ethical reputation. John Harker describes how Citigroup is taking a bottom‐up approach to building a culture of ethics and shared responsibility.
Recent New Drug Approvals. Part 1: Drugs with Pediatric Indications

This two-part review provides information about drugs that have been recently approved by the Food and Drug Administration and focuses on drugs approved with pediatric indications or approved in adults with active pediatric studies. Information was obtained from the product labeling and selected published studies. Part 1 reviews recently approved drugs with labeled pediatric indications, and Part 2 will review recent drug approvals in adults that have potential use in pediatrics and have active studies.
Control of stefan problems by means of linear-quadratic defect minimization

We investigate the following problem: To influence a heat conduction process in such a way that the conductor melts in a prescribed manner. Since we treat a linear auxiliary problem, it suffices to deal with a linear-quadratic defect minimization problem with linear restrictions, where we use splines or polynomials as approximation spaces. In case of exact controllability we derive various order of convergence estimates, which we discuss for some numerical examples.
Association of Species and Their Relationship to Microtopography Within Old Fields

The relationship of vegetational pattern to edaphic environment was examined within the old—field—prairie ecotone of a central Wisconsin drained marsh. Examination of several soil factors established significant correlations between the elevation gradient (with a range of 1.5 m) and organic matter content and moisture. Several species showed definite peaks of frequency and density across the elevation gradient with the invading prairie species predominating on the low ridges and wetland species largely restricted to depressions. Old—field species, such as Poa pratensis and Linaria vulgaris, were present on all topographic positions but appeared to be yielding to competition with the above species groups at the extremes of the elevation gradient. Pattern of species groups was further investigated by the use of normal association analysis. Environmental differences were tested between the resulting subdivisions of this analysis; this further documented the influence of microtopography on the distribution of the vegetation. In addition, organic matter levels were shown to be important in species distribution where differences in elevation were not in control. Normal association analysis and environmental correlation are considered in regard to the continual nature of plant distribution.
Exposed tree root analysis as a dendrogeomorphic approach to estimating bank retreat at the South River, Virginia

Abstract We use a biometric approach based on anatomical changes in the wood of exposed tree roots to quantify riverbank erosion along South River, Virginia, a site where commonly applied techniques for determining bank erosion rates are either not appropriate because of the required spatial scale of analysis (i.e., erosion pins, traditional surveys, LiDAR analysis) or have failed to detect obvious erosion (i.e., photogrammetric techniques). We sampled 73 exposed roots from 22 study reaches and identified the year of exposure macroscopically (2 to 20 times magnification) and microscopically (20 to 100 times magnification), comparing the estimated erosion rates between levels of magnification and to those obtained with photogrammetric techniques. We found no statistical differences between the results of macroscopic and microscopic analyses ( t -test, α = 0.01) but encountered difficulty in identifying the year of root exhumation in some samples. When comparing exposed root analysis to photogrammetric techniques, the results indicate that the exposed root approach is a feasible and effective method for estimating annual- to decadal-scale bank erosion. In addition to producing erosion rates statistically indistinguishable from photogrammetric techniques at sites with erosion rates large enough for detection using historical aerial photographs (regression analysis and t -test, α = 0.01), exposed root analysis was able to estimate erosion rates at sites where photogrammetric techniques failed. We also identify deciduous species well suited for this approach ( Fraxinus pennsylvanica ) and others that prove more problematic (e.g., Acer negundo , Celtis occidentalis , Acer saccharinum ). This study is significant because it describes a robust tool that provides insights into annual- to decadal-scale erosion where other commonly applied techniques may not be appropriate or easily applied.
Use of spin-polarized electron-energy-loss spectroscopy to investigate dipole and impact scattering from transition-metal surfaces

Spin polarized electron-energy-loss spectra have been obtained from Ag(100), Cu(100), Mo(110) and unmagnetized Co(110) and Fe(100) surfaces, in both specular and off-specular scattering geometries, by use of a low-energy polarized incident beam coupled with energy- and angle-resolved spin analysis of the scattered electrons. The data are interpreted in terms of a model that takes account of both dipole and impact scattering. Dipole scattering preserves the full polarization of the incident beam, whereas the scattered electron polarization is degraded by electron exchange in impact-scattering events that produce electron-hole pair excitation in the target. It is found that dipole scattering dominates at noble-metal surfaces but that the impact- and dipole-scattering rates are comparable for targets with incompletely filled d shells. The data also suggest that impact scattering, like dipole scattering, tends to be concentrated in the specular direction. {copyright} {ital 1997} {ital The American Physical Society}