cssi/SciSciGPT-SciSciNet huggingface dataset:
The effect of dimethyl sulfoxide on cholesterol and bile acid metabolism in rats.

AbstractThe effect of DMSO on cholesterol and bile acid metabolism was studied in rats. Male Sprague-Dawley rats were randomly assigned to one of two groups and given either tap water or 2% DMSO (v/v) in tap water to drink for 9 days. Both food (stock rat diet) and water were available ad libitum. Animals in both groups gained weight equally throughout the study. They also had similar liver weights (g/100 g body wt) at the end of the study (control: 5.0 ± 0.1 (N = 6) vs DMSO: 4.9 ± 0.1 (N = 6)). The activity of hepatic cholesterol 7α-hydroxylase (pmole/mg/min), the rate-limiting enzyme of bile acid biosynthesis, was significantly (P < 0.005) reduced in the treated animals (control: 9.7 ± 1.0 (N = 6) vs DMSO: 4.3 ± 0.7 (N = 6)). Plasma cholesterol (mg/dl) was significantly (P < 0.005) elevated in the treated animals (control: 90 ± 3 (N = 6) vs DMSO: 107 ± 4 (TV = 6)), a finding consistent with the reduced CH-7α hydroxylase activity in this group. DMSO treatment did not affect either microsomal cholesterol ...
Normothermic versus hypothermic hyperkalemic cardioplegia: effects on myocyte contractility.

Abstract Background . This study was designed to determine the effects of prolonged hyperkalemic cardioplegic arrest under normothermic or hypothermic conditions with respect to left ventricular myocyte contractile performance and β-adrenergic responsiveness. Methods . Isolated left ventricular porcine myocytes were randomly assigned to one of three groups: (group 1) normothermic control, (group 2) hypothermic cardioplegic arrest, or (group 3) normothermic cardioplegic arrest. Myocyte contractility was evaluated by high-speed video microscopy at baseline and after β-adrenergic stimulation with isoproterenol (25 nmol/L). Results . Myocyte velocity of shortening was decreased after both hypothermic and normothermic cardioplegic arrest (68 ± 2 and 69 ± 2 μm/s, respectively) compared with normothermic control values (96 ± 2 μm/s; p p = 0.5356). With β-adrenergic stimulation, myocyte velocity of shortening was 186 ± 4 μm/s in the hypothermic and 176 ± 3 μm/s in the normothermic cardioplegia groups ( p = 0.0563). However, myocyte contractility with β-adrenergic stimulation was reduced in both cardioplegia groups compared with normothermic controls (205 ± 4 μm/s; p Conclusions . Hyperkalemic cardioplegic arrest under either normothermic or hypothermic conditions resulted in an equivalent reduction in baseline myocyte contractile function with reperfusion/rewarming. Hypothermic cardioplegic arrest may have provided mild protective effects on β-adrenergic responsiveness. Nevertheless, these results suggest that an important contributory factor for diminished myocyte contractility after simulated cardioplegic arrest was prolonged exposure to a hyperkalemic environment.
Termination: Legal and Ethical Considerations for Marriage and Family Therapists

Every Marriage and Family Therapist (MFT) must carefully plan how to initiate, convene, and terminate therapy. Determining how to ethically terminate therapy in a variety of therapeutic contexts can be challenging. Though termination is a common aspect of all therapeutic relationships, a lack of empirically based information on how to terminate therapy leaves practitioners alone in determining how best to end the treatment relationship. Furthermore, the subject of termination is discussed so scarcely in MFT literature that few authors have attempted to establish a standard for ethical termination. In the current climate of evidence-based services, predetermined session limits, and increased litigation for malpractice, MFTs must examine their termination procedures. This paper identifies the current available literature on termination and discusses the ethical and legal considerations for practicing MFTs as outlined by the AAMFT Code of Ethics (2004). Directions and suggested methods for future research ar...
Stochastic upscaling in solid mechanics: An excercise in machine learning

This paper presents a consistent theoretical and computational framework for upscaling in random microstructures. We adopt an information theoretic approach in order to quantify the informational content of the microstructural details and find ways to condense it while assessing quantitatively the approximation introduced. In particular, we substitute the high-dimensional microscale description by a lower-dimensional representation corresponding for example to an equivalent homogeneous medium. The probabilistic characteristics of the latter are determined by minimizing the distortion between actual macroscale predictions and the predictions made using the coarse model. A machine learning framework is essentially adopted in which a vector quantizer is trained using data generated computationally or collected experimentally. Several parallels and differences with similar problems in source coding theory are pointed out and an efficient computational tool is employed. Various applications in linear and non-linear problems in solid mechanics are examined.
Influence of aerobic exercise activity and relaxation training on coping with test-taking anxiety

Abstract This study compared the effects of three types of activity on coping with test-taking anxiety. A total of 52 undergraduate students were randomly assigned to one of three conditions: aerobic exercise, relaxation training, or control (i.e., magazine reading). State anxiety was measured three times during the experiment using an abbreviated version of the Multiple Affect Adjective Checklist. Analysis using a 2x3 (sex by group) analysis of variance found that aerobic exercise and relaxation training were associated with reduction of general and test-taking anxiety. Men reported lower test-taking anxiety and responded better to aerobic exercise, whereas women responded better to magazine reading. Implications and suggestions for research were discussed.
A three-dimensional electrostatic particle-in-cell methodology on unstructured Delaunay-Voronoi grids

The mathematical formulation and computational implementation of a three-dimensional particle-in-cell methodology on unstructured Delaunay-Voronoi tetrahedral grids is presented. The method allows simulation of plasmas in complex domains and incorporates the duality of the Delaunay-Voronoi in all aspects of the particle-in-cell cycle. Charge assignment and field interpolation weighting schemes of zero- and first-order are formulated based on the theory of long-range constraints. Electric potential and fields are derived from a finite-volume formulation of Gauss' law using the Voronoi-Delaunay dual. Boundary conditions and the algorithms for injection, particle loading, particle motion, and particle tracking are implemented for unstructured Delaunay grids. Error and sensitivity analysis examines the effects of particles/cell, grid scaling, and timestep on the numerical heating, the slowing-down time, and the deflection times. The problem of current collection by cylindrical Langmuir probes in collisionless plasmas is used for validation. Numerical results compare favorably with previous numerical and analytical solutions for a wide range of probe radius to Debye length ratios, probe potentials, and electron to ion temperature ratios. The versatility of the methodology is demonstrated with the simulation of a complex plasma microsensor, a directional micro-retarding potential analyzer that includes a low transparency micro-grid.
A randomized trial of contingency management for adolescent marijuana abuse and dependence.

Abstract An initial efficacy test of an innovative behavioral outpatient treatment model for adolescents with problematic use of marijuana enrolled 69 adolescents, aged 14–18, and randomly assigned them to one of two treatment conditions. Both conditions received individualized Motivational Enhancement and Cognitive Behavioral Therapy (MET/CBT) and a twice-weekly drug-testing program. The experimental contingency management condition involved a clinic-delivered, abstinence-based incentive program, and weekly behavioral parent training sessions that included a parent-delivered, abstinence-based, substance monitoring contract. The comparison condition included an attendance-based incentive program, and weekly psychoeducational parent sessions. Follow-up assessments were performed at 3, 6, and 9 months post-treatment. The experimental condition showed greater marijuana abstinence during treatment, e.g., 7.6 vs. 5.1 continuous weeks and 50% vs. 18% achieved ≥10 weeks of abstinence. Improvements were found in parenting and youth psychopathology across treatment conditions, and improvements in negative parenting uniquely predicted post-treatment abstinence. The outcomes observed in the experimental condition are consistent with adult substance-dependence treatment literature, and suggest that integrating CM abstinence-based approaches with other empirically based outpatient interventions provides an alternative and efficacious treatment model for adolescent substance abuse/dependence. Replication and continued development of more potent interventions remain needed to further advance the development of effective substance abuse treatments for adolescents.
Using Classic Circuit Analysis Methods to Describe Voltage Performance of Battery-Ultracapacitor Power Source:

Circuit analysis methods taught in principles of engineering courses were used to develop instructional material for inclusion in teaching a course on Energy Systems Projects. The course involves l...
Fast Lexicon-Based Scene Text Recognition with Sparse Belief Propagation

Using a lexicon can often improve character recognition under challenging conditions, such as poor image quality or unusual fonts. We propose a flexible probabilistic model for character recognition that integrates local language properties, such as bigrams, with lexical decision, having open and closed vocabulary modes that operate simultaneously. Lexical processing is accelerated by performing inference with sparse belief propagation, a bottom-up method for hypothesis pruning. We give experimental results on recognizing text from images of signs in outdoor scenes. Incorporating the lexicon reduces word recognition error by 42% and sparse belief propagation reduces the number of lexicon words considered by 97%.
The impact of IS Department organizational environments upon project team performances

Projects depend on the effectiveness of teams to be successful. In the past, researchers studied team characteristics in an attempt to find successful combinations of traits that promote team performance. This study examines the relation of the organizational traits of centralization, formalization and maturity to the performance of the team. These organizational influences on the environment are related to overall project team performance, especially the traits of centralization and maturity. The results of the study suggest that organizational structure must be considered when fostering successful projects, particularly those related to planning and authority.
I: The nature of living systems

Abstract General systems behavior theory is a set of related definitions, assumptions, and propositions which deal with reality as an integrated hierarchy of organizations of matter and energy. General systems behavior theory is concerned with a special subset of all systems, the living ones. Even more basic to this presentation than the concept of “system” are the concepts of “space”, “time”, “matter”, “energy”, and “information”, because the living systems discussed here exist in space and are made of matter and energy organized by information.
Bayesian multiscale approach to joint image restoration and edge detection

This paper presents a novel wavelet-based method for simultaneous image restoration and edge detection. The Bayesian framework developed here is general enough to treat a wide class of linear inverse problems involving (white or colored) Gaussian observation noises, but we focus on convolution operators. In our new approach, a signal prior is developed by modeling the signal/image wavelet coefficients as independent Gaussian mixture random variables. We specify a uniform (non-informative) distribution on the mixing parameters, which leads to an extremely simple iterative algorithm for joint MAP restoration and edge detection. This algorithm is similar to the popular EM algorithm in that it alternates between a state estimation step and a maximization step, yet it is much simpler in each step and has a very intuitive derivation. Moreover, we show that our algorithm converges monotonically to a local maximum of the posterior distribution. Experimental results show that this new method can perform better than wavelet-vaguelette type methods that are based on linear inverse filtering followed by wavelet coefficient denoising.
Structural Stability and Virtual Team Conflict

Current IS research is inconclusive about the role of conflict within virtual teams (VTs). In this paper, we argue that conflict should be treated as part of the process and not as an antecedent or post-facto analysis to VT performance. We propose the concept of conflictual balance, grounded in structural balance theory (SBT) [12], to study the complex relationship between conflict and VT performance. Our paper proposes to answer the following research questions: "do virtual teams develop structural stability over time" and "is there a relationship between structural stability, conflict, and virtual team performance within a project?" As our paper is a research in progress, it is broken into two sections: a theoretical section and empirical section. The empirical section proposes a new research model that will be tested as a next step in the research process.
Right atrial myxoma with a nonembolic intestinal manifestation.

A 5-year-old male with right atrial myxoma without interatrial communication who presented with abdominal pain, vomiting, fever, and guaiac positive stool is reported. He was later found to have ischemia of a jejunal segment necessitating segmental resection. Although his symptoms persisted postoperatively, surgical removal, of a right atrial myxoma was followed by complete resolution of his intestinal symptoms. We demonstrated that the mesenteric vasculitis was of nonembolic origin, and we speculate autoimmune arteritis as a possible mechanism.
Radiographic diagnosis of quadriceps tendon rupture: Analysis of diagnostic failure

In a multi-institution study, 18 knees with complete quadriceps tendon ruptures (QTRs) were reviewed to analyze the cause of failure in radiographic diagnosis. Only 6 of the 18 knees were diagnosed correctly initially. This occurred even though almost all knee radiographs showed more than three abnormalities compatible with QTR (obliteration of quadriceps tendon, suprapatellar mass, suprapatellar calcific density, or patella baja). Of the 12 diagnostic failures, only 3 were considered to be complete failure. Nine primary reports (50%) were classified as incomplete diagnosis and could be correctly diagnosed if the attention of radiologists was focused to the quadriceps mechanism. We conclude that better understanding of radiographic abnormalities in QTR is necessary for the improvement of primary radiological diagnosis.
Immersed essential surfaces and Dehn surgery

Abstract It is known that an embedded essential surface F in a hyperbolic manifold M remains essential in Dehn filling spaces M(γ) for most slopes γ on a torus boundary component T of M. The main theorem of this paper is to generalize this result to immersed surfaces. More explicitly, if an immersed essential surface F has coannular slopes β1,…,βn on T, then there is a constant K such that F remains essential in M(γ) when Δ(γ,βi)>K for all i. It will also be shown that all but finitely many Freedman tubings of a geometrically finite surface in M are π1-injective.
Erythropoietin and the incidence of necrotizing enterocolitis in infants with very low birth weight.

Abstract Background/Purpose: The presence of erythropoietin (Epo) in human milk and the expression of Epo receptors on intestinal villous enterocytes of neonates suggest that Epo has a role in growth and development of the gastrointestinal tract. On this basis, the authors hypothesized that recombinant Epo (rEpo) given for prevention or treatment of the anemia of prematurity would protect against necrotizing enterocolitis (NEC). Methods: A retrospective cohort study was conducted from a university neonatal intensive care unit of 483 very low birth weight (500 to 1,250 g) neonates born from July 1, 1993 to January 1, 1998. Results: A total of 260 neonates received rEpo, and 223 did not (control group). The rEpo and control groups were similar in gender distribution (52% v 48% boys), gestational age (26.8 ± 2.1 v 27.6 ± 2.9 weeks; mean ± SD), birth weight (895 ± 198 v 911 ± 208 g), 1 and 5 minute Apgar scores (4.2 and 6.1 v 4.7 and 6.7), and incidence of severe intraventricular hemorrhage (8.9% v 10.3%). The rEpo group had a lower incidence of NEC (12 of 260, 4.6% v 24 of 223, 10.8%; P =.028, 95% confidence interval for difference: −0.108 to −0.015). Conclusion: In very low birth weight infants, the incidence of NEC is lower in those who received rEpo. J Pediatr Surg 35:178-182. Copyright © 2000 by W.B. Saunders Company.
Pre-spectrometer optics in a CTEM/STEM

Abstract The experimental operation of a magnetic sector spectrometer with a CTEM/STEM electron microscope is described. Optimum operating conditions for the microscope lenses are predicted and determined experimentally. These optimum lens conditions are defined as those which produce the best energy resolution for a given specimen area and range of scattering angles selected. Also, the angular distributions of characteristic and background energy loss scattering events are such that optimum collection angles exist which produce the maximum peak to background ratios. This experimentally determined optimum aperture angle is then used with the optimum lens conditions to maximize the sensitivity of energy loss microanalysis and a comparison of this sensitivity is made with energy dispersive X-ray microanalysis.
“Their Stories Have Changed My Life”: Clinicians’ Reflections on Their Experience with and Their Motivation to Conduct Asylum Evaluations

Many clinicians perform asylum evaluations yet no studies describe the motivation to perform them or their perceived rewards. The number of asylum seekers in the US is increasing and more clinicians are needed as evaluators. A survey to an asylum evaluators' network asked participants to qualitatively reflect on their experience and motivation. Answers were analyzed for themes and sentiment. Respondents cited commitment to humanistic and moral values, noted personal and family experiences, having skills, expertise, and career interests as drivers. They found the experience very rewarding personally and professionally, and in their perceived benefit to asylees. Negative sentiment was less frequent and centered on emotions related to client narratives. Process-oriented frustrations were also noted. This is the first published study describing clinicians' motivation and experience with asylum evaluations. It may illuminate clinicians' drive to volunteer, and serve as a resource for organizations for recruitment and education.
Pyrolysis of 1,1 dimethylhydrazine for OMVPE growth

A key requirement for the growth of the wide bandgap nitrides, GaN and InGaN, is providing a sufficient supply of atomic nitrogen from the vapor phase during growth. In order to prevent a high concentration of nitrogen vacancies, especially for GaInN, one strategy is to use a precursor with a low pyrolysis temperature, thus yielding a high concentration of atomic nitrogen in the vapor phase. 1,1 dimethylhydrazine (DMHy), with an appropriate vapor pressure of 157 Torr at 25°C and a low pyrolysis temperature (T50∼420°C), is a promising candidate to replace NH3, the most common nitrogen source. The pyrolysis studies of DMHy suggest the rate limiting step for decomposition is a heterogeneous, unimolecular process that is independent of both input concentration and ambient. Radical reactions are also involved as indicated by the products. In He they include CH4, NH3, N2, H2, HCN, C2H6, CH3NCH2, and (CH3)2NH. Experiments on the copyrolysis of DMHy and trimethylgallium show that an adduct is formed at room temperature followed by CH4 elimination, presumably forming (CH3)2GaNHN(CH3)2. At higher temperatures, the products indicate that the covalent Ga-N bond doesn’t dissociate during pyrolysis.
The relationship between American women's preventive dental behavior and dental health beliefs

The data collected from a national family dental survey on wives of white American families were used to examine the relationships between the wives' toothbrushing, flossing and preventive dental visits and their health beliefs. A statistically significant canonical correlation (rc = 0.436, P less than 0.001) demonstrated that American women's success or failure to engage in preventive dental behavior was related to their health beliefs. The dental visit, as opposed to toothbrushing and dental flossing, had the highest level of predictability with structure coefficient of 0.936. Perceptions of salience and barriers were more powerful predictors (structure coefficients 0.721 and -0.757, respectively). The correlation accounted for about one-fifth of the variance of preventive dental behavior. Further research is needed to extend these findings to both sexes and all races.
Role of the Mitogen-Activated Protein Kinases in Cytokine-Mediated Inhibition of Insulin Gene Expression

Background Following islet transplant, inflammatory cells in the vicinity of the transplant graft elaborate cytokines that contribute to islet graft dysfunction. To better understand the mechanism for this effect of cytokines on graft function, we examined the impact of cytokines on intracellular signaling and insulin promoter activity in pancreatic beta cells. Methods Two pancreatic beta cell lines, RINm5F and MIN6 cells, were transfected with a rat insulin promoter (RIP) luciferase fusion gene and treated with a combination of cytokines, including 5 ng/mL interleukin-1β + 10 ng/mL tumor necrosis factor α + 25 ng/mL interferon-γ. The effect of cytokines on beta cell transcription factors and signaling pathways was analyzed by real-time reverse transcriptase polymerase chain reaction and Western blotting. Results Treatment for 48 hours with the combination of cytokines decreased insulin 1 messenger ribonucleic acid (mRNA) levels to 51% and 38% and RIP1 activity to 16% and 30% of control levels in RINm5F and MIN6 cells, respectively. The level of mRNAs encoding transcription factors important for insulin gene expression and beta cell function, including MafA, PDX-1, Nkx6.1, and Pax6, was also decreased by cytokine treatment. Cytokines increased phosphorylation of ERK and c-Jun NH2-terminal kinase (JNK) in RINm5F and MIN6 cells but had no effect on p38 kinase phosphorylation. Neither JNK nor ERK inhibition had a significant effect on cytokine-mediated inhibition of RIP1 activity. Conclusion Beyond modulating beta cell survival, cytokines inhibit insulin promoter activity, which likely contributes to islet dysfunction following islet transplant. This effect appears to be mediated, in part, via altered expression of transcription factors important for insulin gene expression.
Optimization Process of Biomass Combustion in the Advanced FBC Using Factorial Design and Response Surface Methodology

This paper studied the optimization process of the combustion of poultry waste material (i.e. poultry manure) in an advanced fluidized bed combustor (FBC) with the secondary air tangential injection. In order to test the influences of combustion parameters on the carbon combustion efficiency, factorial design (FD) and response surface methodology (RSM) were applied in the experimental process and data analysis. The parameters studied were moisture content, waste/natural gas ratio, excess air ratio, secondary/total air ratio, and the height levels of the secondary air injection. Using the 25−1 fractional factorial design, moisture content, excess air and secondary air injection height were found to be significant for the carbon combustion efficiency at the critical level of type-I error α = 0.1. The RSM was used to approach the optimal combustion condition. The optimal condition regarding the significant factors was found. Then the data from a validation experiment was compared with the computed combustion efficiency under the optimal condition. The result showed the combustion efficiency for poultry manure can reach up to 83%, which indicated that the poultry manure could be effectively burned in the advanced FBC.Copyright © 2005 by ASME
Assessment of the Effectiveness of an Online Learning System in Improving Student Test Performance

Colleges and universities, particularly public institutions, are facing higher enrollments and declining resources from state and federal governments. In this resource-constrained environment, faculty are seeking more efficient and effective teaching strategies to improve student learning and test performance. The authors assessed an online learning system's effectiveness for improving student test performance in a face-to-face learning environment. Results indicated that implementation of the online learning system improved student test performance compared with control test questions and with test performance during a prior semester before system implementation. Implications and limitations are discussed.
The Distance Between Selves: The Influence of Self-Discrepancy on Purpose in Life

The present investigation (total N = 643) sought to examine for the first time self-discrepancy theory in relation to purpose in life. Negative associations were found between purpose and discrepancies in perceptions of one's actual and ideal personality (Study 1) and body image (Study 2). Study 3 further demonstrated experimentally that individuals describing differences between their actual and ideal physique reported less purpose than those describing similarities. Finally, Study 4 sought to compare the effects of actual/ideal and actual/ought self-discrepancies on purpose in life. Participants who wrote about differences between their actual/ideal or actual/ought selves subsequently reported less purpose than those who wrote about similarities between these domains. However, neither a main effect nor an interaction emerged between actual/ideal versus actual/ought conditions, thereby suggesting that greater discrepancy denigrated purpose independent of self-domain. Importantly, agency emerged as a mech...
Subjective powerlessness, sex, and suicide potential.

This study assessed the relationship for 25 suicide attempters, 30 threateners, and 30 controls of their scores on the Seeman-Rotter powerlessness scale. The scale did discriminate between male attempters and male threateners, and separated the suicidal samples from the nonsuicidal.
Gender Stereotypes and Attitudes Toward Gender Balance in Government

The desire to elect more women to public office is likely to affect a range of political behaviors and may explain the relatively low levels of women's descriptive representation overall. Yet, little is known about the public's view of the ideal gender composition of government. We find that the public expresses a preference for higher levels of women's representation than the country has experienced. Women are more likely than men to express a view, though men and women do not differ in their preferences on the ideal percentage of male officeholders. We examine the role of gender stereotypes and the experience of being represented by women officeholders in shaping support for women's representation.
Vegetation dynamics in a Quercus-Juniperus savanna: An isotopic assessment

Woody plants are increasing in many grassland and savanna ecosystems around the world. As a case in point, the Edwards Plateau of Texas, USA, is a vast region (93 000 km 2 ) in which rapid woody encroachment appears to be occurring. The native vegetation (prior to the Anglo-European settlement 150 - 200 yr ago) and the biogeochemical consequences of woody encroachment in this region, however, are poorly un- derstood. To assess these matters we measured plant and soil δ 13 C, soil organic C and soil N content from grasslands and two important woody patch types (mature Quercus virginiana clusters and Juniperus ashei woodlands) in this region. Soil δ13C values showed that relative productivity of C 3 species has increased in grassland and both woody habitats in recent times. δ 13 C of SOC in grasslands and Q. virginiana clusters increased with depth from the litter layer to 30 cm (grasslands = - 21 to - 13‰; Q. virginiana clusters = - 27 to - 17‰) and were significantly different between habitats at all depths, indicating that Q. virginiana has been a long-term component of the landscape. In J. ashei woodlands, soil δ 13 C values (at 20 - 30 cm depth) near the woodland edge (-13‰) converged with those of an adjacent grassland (-13‰) while those from the woodland interior (-15‰) remained distinct, indicating that the woodland has been present for many years but has recently expanded. Concentrations and densities of SOC and total N were generally greater in woody patches than in grasslands. However, differences in the amount of SOC and N stored beneath the two woody patch types indicates that C and N sequestration potentials are species dependent.
Clustering supercomputer nodes using high-density parallel optic interconnects

Clustering supercomputer nodes requires a large amount of bandwidth in as small an area as possible. The distance between nodes can be quite varied, and interconnects covering 30 meters between nodes are not uncommon. Current advances in parallel optic interconnects allow these devices to be given consideration to replace the more traditional electrical and copper cable interconnect. However, supercomputer communication boards often need to support and route 1,000 to 1,200 communications lines. We build and demonstrate a parallel optic interconnect module with a bandwidth density of 15Gb/s/inch2 and an optical connector housing supporting 16 MT ferrules to satisfy the needs of a system communication module.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
On completion problems for various classes of P-matrices

Abstract A P -matrix is a real square matrix having every principal minor positive, and a Fischer matrix is a P -matrix that satisfies Fischer’s inequality for all principal submatrices. In this paper, all patterns of positions for n × n matrices, n ⩽ 4, are classified as to whether or not every partial Π -matrix can be completed to a Π -matrix for Π any of the classes positive P -, nonnegative P -, or Fischer matrices. Also, all symmetric patterns for 5 × 5 matrices are classified as to completion of partial Fischer matrices, and all but two such patterns are classified as to positive P - or nonnegative P -completion. We also show that any pattern whose digraph contains a minimally chordal symmetric-Hamiltonian induced subdigraph does not have Π -completion for Π any of the classes positive P -, nonnegative P -, Fischer matrices.
Imaginary part of a resonance in barrier penetration

Abstract A simple model of quantum mechanical barrier penetration is discussed in which a certain resonance converges to a true bound state energy of a limiting Hamiltonian as the width R of the barrier tends to infinity. An asymptotic formula for the imaginary part of this resonance for large R is obtained, and compared with the standard quasi-classical approximation.
NOCTURNAL BIOACTIVE FSH PULSES ARE EVIDENT IN PRE (PERI) PUBERTAL BOYS

Secretion of both LH and FSH is pulsatile and maximal during the night in early peripubertal boys. To evaluate the pulsatile pattern of bioactive FSH (B-FSH), we assessed serum concentrations of B-FSH in four Tanner Stage I boys with constitutional growth delay (mean age 15y 3m, mean bone age 12y 6m) and compared their data to previously published data from 6 Tanner Stages II-III pubertal boys (Hassing et al, JCEM, 1990, 70:1082). Each of the four boys had a 12 h overnight blood sampling (every 20 min) followed by administration of 1μg/kg nafarelin sc. Serum I-LH and I-FSH were measured by RIA and B-FSH was measured by the rat Sertoli cell aromatase induction assay using hLH-13 and hFSH-13 standards and expressed as ng/ml. The mean serum I-LH, I-FSH and B-FSH were 0.63±0.06, 0.40±0.15 and 1.8±0.2 ng/mL (p<0.05, B vs I FSH). B-FSH pulse frequency was similar to I-LH pulse frequency (0.43±0.1 and 0.43±0.05 pulses/boy/h) and to previously published data in mid pubertal boys. ΔI-LH release was 3.3±0.7, ΔI-FSH was 2.4±0.6 and ΔB-FSH was 4.2±1.4 ng/mL. We conclude that during the peripubertal period in boys, serum B-FSH is secreted in a pulsatile manner and the concentrations exceed those of serum I-LH or I-FSH.
Basal Lamina of Abdominal Skeletal Muscle Capillaries in Diabetics and Nondiabetics

In a "blind" study, skeletal muscle biopsies were obtained from the trunk of 13 nondiabetics, eight chemical diabetics, and four overt diabetics of comparable age. On electron micrographs of 20 capillaries from each case, the areas of various components of the capillary structure were measured with a planimeter. The area of the basal lamina was expressed as a percentage of the total vessel area. This method for measuring objectively the relative thickness of capillary basal lamina considered the vessel size, plane of sectioning, and the function state of the vessel. The theoretical validity of the method is discussed. The widths of the basal lamina of the capillaries of the trunk skeletal muscles of both diabetics and nondiabetics were identical. Morphological differences between the two groups were not present. The discrepancies in results of investigations concerned with the quantity of basal lamina in capillaries of skeletal muscle may be due to naturally occurring regional differences, or because capi...
Pressure‐Flow Relationships for Packed Beds of Compressible Chromatography Media at Laboratory and Production Scale

Pressure drop across chromatography beds employing soft or semirigid media can be a significant problem in the operation of large-scale preparative chromatography columns. The shape or aspect ratio (length/diameter) of a packed bed has a significant effect on column pressure drop due to wall effects, which can result in unexpectedly high pressures in manufacturing. Two types of agarose-based media were packed in chromatography columns at various column aspect ratios, during which pressure drop, bed height, and flow rate were carefully monitored. Compression of the packed beds with increasing flow velocities was observed. An empirical model was developed to correlate pressure drop with the aspect ratio of the packed beds and the superficial velocity. Modeling employed the Blake-Kozeny equation in which empirical relationships were used to predict bed porosity as a function of aspect ratio and flow velocity. Model predictions were in good agreement with observed pressure drops of industrial scale chromatography columns. A protocol was developed to predict compression in industrial chromatography applications by a few laboratory experiments. The protocol is shown to be useful in the development of chromatographic methods and sizing of preparative columns.
The effects of pulse charging on cycling characteristics of commercial lithium-ion batteries

The effects of a pulse charging technique on charge–discharge behavior and cycling characteristics of commercial lithium-ion batteries were investigated by comparison with the conventional direct current (dc) charging. The impedance spectra and cycling voltammograms of Li-ion batteries cycled by both protocols have been measured. The individual electrodes in the batteries have also been examined using XRD and SEM. The results show that pulse charging is helpful in eliminating concentration polarization, increasing the power transfer rate, and lowering charge time by removing the need for constant voltage charging in the conventional protocol. Pulse charging interrupts dc charging with short relaxation periods and short discharge pulses during charging, and also improves the active material utilization giving the battery higher discharge capacity and longer cycle life. Impedance measurements show that the magnitude of the interfacial resistance of the batteries cycled both by pulse charging and dc charging is small. However, at the same number of cycles, the interfacial resistance of the pulse charged battery is larger than that of dc charged. The batteries after 300 cycles charged by pulse charging show higher peak currents during both forward and reverse scans indicating higher reversibility of the electrodes. XRD and SEM studies of the individual electrodes indicate that pulse charging maintains the stability of the LiCoO2 cathode better than dc charging and inhibits the increase in the thickness of the passive film on the anode during cycling.
Inside Front Cover: Nanocrystalline TiO2 Photocatalytic Membranes with a Hierarchical Mesoporous Multilayer Structure: Synthesis, Characterization, and Multifunction (Adv. Funct. Mater. 8/2006)

The inside cover shows a hierarchical, mesoporous, multilayer TiO2 photocatalytic membrane synthesized via a novel sol–gel dip-coating process employing surfactant templates reported by Dionysiou and co-workers on p. 1067. The resulting asymmetric mesoporous TiO2 membrane supported onto a porous Al2O3 substrate exhibited hierarchical changes in pore diameter and materials porosity from the top to the bottom layer. The TiO2 membrane has multiple simultaneous functions, including photocatalysis, disinfection, separation, and anti-biofouling. A novel sol–gel dip-coating process to fabricate nanocrystalline TiO2 photocatalytic membranes with a robust hierarchical mesoporous multilayer and improved performance has been studied. Various titania sols containing poly(oxyethylenesorbitan monooleate) (Tween 80) surfactant as a pore-directing agent to tailor-design the porous structure of TiO2 materials at different molar ratios of Tween 80/isopropyl alcohol/acetic acid/titanium tetraisopropoxide = R:45:6:1 have been synthesized. The sols are dip-coated on top of a homemade porous alumina substrate to fabricate TiO2/Al2O3 composite membranes, dried, and calcined, and this procedure is repeated with varying sols in succession. The resulting asymmetric mesoporous TiO2 membrane with a thickness of 0.9 μm exhibits a hierarchical change in pore diameter from 2–6, through 3–8, to 5–11 nm from the top to the bottom layer. Moreover, the corresponding porosity is incremented from 46.2, through 56.7, to 69.3 %. Compared to a repeated-coating process using a single sol, the hierarchical multilayer process improves water permeability significantly without sacrificing the organic retention and photocatalytic activity of the TiO2 membranes. The prepared TiO2 photocatalytic membrane has great potential in developing highly efficient water treatment and reuse systems, for example, decomposition of organic pollutants, inactivation of pathogenic microorganisms, physical separation of contaminants, and self-antifouling action because of its multifunctional capability.
Student Perceptions of Nurse Doctorates: Similarities and Differences.

This study explored, from a student perspective, similarities and differences between three types of doctoral programs in nursing: doctor of education (EdD), doctor of nursing science (DNSc), and the doctor of philosophy (PhD). Specifically, the study focused on student perceptions of personal and professional growth, research preparation, available support systems, and role preparation within the three types of doctoral programs. Data were collected using a mailed questionnaire that was developed from an earlier qualitative investigation. The findings of the study indicated that there were no significant differences between PhD, EdD, and DNSc students on the first factor, personal and professional growth. Attaining a doctorate was perceived to be enriching from both a personal as well as a professional perspective. A significant difference on the factor related to research was noted by the participants. Although students recognized the programs they were enrolled in as preparing them for research, when asked about other programs, students perceived PhD programs as preparing nurses to conduct research. Support in doctoral programs from faculty and peers was strong, and there was no significant difference on this factor. The fourth and final factor, related to role preparation, did note a significant difference. PhD students did not perceive the doctorate as preparing them for roles as educators, practitioners, or administrators. The results indicate that students do perceive differences in the doctoral education process, particularly in the area of research preparation. It is important that faculty in doctoral programs continue to assess what doctoral graduates view as the primary emphasis of their programs to understand future curricular, academic, and support needs of students.
Purification and characterization of isoaccepting species of phenylalanyl-transfer ribonucleic acid from rat liver.

Abstract Four isoacceptor species of phenylalanyl-tRNA, from rat-liver total tRNA, have been purified to homogeneity using sequential chromatography on BD-cellulose and reversed-phase-5 (RPC-5) columns. Re-chromatography of individual species (I–IV) on RPC-5 columns revealed chromatographic homogeneity (single peak, same site and height of elution) and biological homogeneity since none of the species accepted amino acids other than phenylalanine. Thermal denaturation profiles and circular dichroism spectral patterns suggested that these species exist in two major conformations.
New Tools For Studies Of Membrane Protein Dimerization In Mammalian Membranes

Receptor Tyrosine Kinases (RTKs) play key roles in cell growth, differentiation, metabolism, and migration. These single-pass receptors conduct biochemical signals by dimerizing in the plasma membrane. The process of lateral dimerization, which controls the distribution between inactive monomers and active dimers, serves as a key regulator of the biochemical processes that determine cell fate. Enhanced dimerization leads to persistent autocrine activation and tumorigenesis, or impaired growth. An understanding of the dimerization process as a function of interaction energies, protein concentration and ligand concentration, is lacking. Our laboratory is developing methodologies that yield quantitative information about RTK dimerization and activation in cellular membranes. These methods will enable biomedical researchers to study the quantitative aspects of signal transduction in the context of the biological membrane.
Listening/speaking in second and foreign language teaching

Abstract Communication, the key to language development, is a rich dynamic unfolding interplay of meanings among people. Listening and speaking are two networks within the much bigger communicative whole. Interdisciplinary perspectives on the dynamic nature of communication help define some of the interrelationships between listening and speaking as language programs increasingly tend to integrate the teaching and learning of these and other skills. These perspectives also point to a multitude of input/output possibilities, purposes for which we speak and listen, specific skills involved in accomplishing such purposes and learner strategies that enhance general awareness among students of how they (can) learn. This article not only lays out some of the broad parameters language teachers, curriculum designers and materials creators face as they grapple with listening/speaking connections. It also offers a set of basic principles to guide such specialists in meeting the enormous yet worthwhile challenges the integration of these two language skills demands of them.
Biodiversity and community composition of sediment macrofauna associated with deep-sea Lophelia pertusa habitats in the Gulf of Mexico

Abstract Scleractinian corals create three-dimensional reefs that provide sheltered refuges, facilitate sediment accumulation, and enhance colonization of encrusting fauna. While heterogeneous coral habitats can harbor high levels of biodiversity, their effect on the community composition within nearby sediments remains unclear, particularly in the deep sea. Sediment macrofauna from deep-sea coral habitats ( Lophelia pertusa ) and non-coral, background sediments were examined at three sites in the northern Gulf of Mexico (VK826, VK906, MC751, 350–500 m depth) to determine whether macrofaunal abundance, diversity, and community composition near corals differed from background soft-sediments. Macrofaunal densities ranged from 26 to 125 individuals 32 cm −2 and were significantly greater near coral versus background sediments only at VK826. Of the 86 benthic invertebrate taxa identified, 16 were exclusive to near-coral habitats, while 14 were found only in background sediments. Diversity (Fisher’s α ) and evenness were significantly higher within near-coral sediments only at MC751 while taxon richness was similar among all habitats. Community composition was significantly different both between near-coral and background sediments and among the three primary sites. Polychaetes numerically dominated all samples, accounting for up to 70% of the total individuals near coral, whereas peracarid crustaceans were proportionally more abundant in background sediments (18%) than in those near coral (10%). The reef effect differed among sites, with community patterns potentially influenced by the size of reef habitat. Taxon turnover occurred with distance from the reef, suggesting that reef extent may represent an important factor in structuring sediment communities near L. pertusa . Polychaete communities in both habitats differed from other Gulf of Mexico (GOM) soft sediments based on data from previous studies, and we hypothesize that local environmental conditions found near L. pertusa may influence the macrofaunal community structure beyond the edges of the reef. This study represents the first assessment of L. pertusa -associated sediment communities in the GOM and provides baseline data that can help define the role of transition zones, from deep reefs to soft sediments, in shaping macrofaunal community structure and maintaining biodiversity; this information can help guide future conservation and management activities.
Host restriction of Friend Leukemia Virus; fate of input virion RNA

Abstract Host restriction of oncogenesis by RNA tumor viruses may be studied in vitro by measuring the replication of the lymphatic leukemia component of the Friend Virus Complex (LLV-F) in either NIH-Swiss or Balb/C mouse embryo cells. These cells derive from mice differing at the Fv-1 locus, which controls the replication of all murine RNA leukemia viruses. Studies of early events in the replication of LLV-F were carried out by following the infection of permissive and restrictive mouse embryo cells by 32 P labeled LLV-F. 32 P labeled viral genome RNA rapidly becomes associated with cell nuclei and may be found integrated to the same extent with high molecular weight host DNA of either permissive or restrictive cells. These results suggest that Fv-1 mediated host restriction of LLV-F occurs at a step following integration of viral genome RNA into host DNA. Two other conclusions are suggested by these data. The nucleus appears to be the site of activation and synthesis of DNA of the infecting virus; and the "provirus", at least transiently, is represented as an RNA-DNA hybrid molecule covalently integrated with host cell DNA.