cssi/SciSciGPT-SciSciNet huggingface dataset:
Analyzing grouped data with hierarchical linear modeling

Abstract Grouped data are common but often improperly treated in welfare and child welfare research. Conventional regression models are not appropriate for analysis of this type of data, because the presence of intra-class correlation among study subjects from the same group violates the assumption that observations are independent of one another. This study demonstrates the advantages of using hierarchical linear modeling (HLM) to analyze grouped data found in the 1997 Child Development Supplement to the Panel Study of Income Dynamics. Specifically, this article presents an HLM example investigating intergenerational dependence on welfare and its relation to child academic achievement. Results show that HLM is a robust and flexible tool that can effectively test various types of research hypotheses, particularly those concerning multilevel influences and macro-to-micro relations. The study shows that early educational intervention is essential in improving child academic achievement for children receiving welfare, particularly for those who used welfare for most of their own childhood and whose caregivers never used welfare.
Effect of caffeine on LT, VT and HRVT.

Caffeine has many diverse physiological effects including central nervous system stimulation. Ventilatory threshold and a recently described heart rate variability threshold both have a relationship with autonomic control that could be altered by caffeine consumption. The purpose of this investigation was to determine the influence of caffeine on lactate, ventilatory, and heart rate variability thresholds during progressive exercise. Using a randomized placebo controlled, double-blind study design, 10 adults performed 2 graded maximal cycle ergometry tests with and without caffeine (5 mg·kg − 1). Respiratory gas exchange, blood lactate concentrations, and heart rate variability data were obtained at baseline and throughout exercise. At rest, caffeine (p These data demonstrate the robustness of the lactate, ventilatory and heart rate variability thresholds when challenged by a physiological dose of caffeine.
Localizing antigenic determinants in human haemoglobin with mutants: molecular correlations of immunological tolerance.

Abstract It has been found that 7 out of 18 tested single amino-acid mutants of human haemoglobin can be distinguished from A 1 and the remainder are indistinguishable from A 1 by quantitative complement fixation tests with rabbit anti-A 1 sera. The mutations antigenically distinguishable from A 1 occur in regions of the haemoglobin molecule where the primary sequence of rabbit and human haemoglobin are found to vary. Mutations antigenically indistinguishable from normal A 1 are all located in regions of the primary sequence where rabbit and human haemoglobins are identical. The significance of this as regards the number of antigenic regions, the relationship of molecular structure to tolerance, and the molecular localization of possible antigenic determinants in human haemoglobin are discussed.
Characterization of defects in amorphous SiO2 implanted with oxygen ions

Abstract Electron paramagnetic resonance (EPR) spectra of oxygen-implanted high-purity silica at temperatures ranging from 120 to 300 K have been measured at 9.7 GHz. Silica disks 2.0 cm in diameter and 0.1 cm thick were implanted with O + ions at 140 keV with beam currents 2 and doses that ranged from 8 × 10 15 to 8 × 10 16 ions/cm 2 . Paramagnetic defects have been observed, two of which are similar to defects formed by γ-ray irradiation of silica (E' center and the peroxy-radical (POR)). The POR shows several temperature-dependent features while the E' center has a dose-dependent annihilation cross section, as previously reported by Golanski, Devine, and Oberlin [J. Appl. Phys. 56 (1984) 1572]. Implantation of oxygen hinders defect formation of oxygen deficient defects such as the E' center while favoring production of oxygen-excessive defects such as the POR.
Effects of long-term consumption of high doses of fish oil concentrates on clinical parameters in male and female rats.

Many studies suggest that a diet supplemented with fish oil concentrates (FOCs) may provide protection against cardiovascular and other diseases. The possible harmful effects of long-term consumption of high doses of FOCs, however, have not been adequately investigated. Corn oil, fish oil (MaxEPA) and various mixtures of the oils were administered by gavage to 120 male and 120 female rats, 5d/wk for 13 wk at the rate of 5mL/kg/d. Although MaxEPA had no effect on prothrombin time or activated partial thromboplastin time, it caused a statistically significant diminution of the total serum cholesterol level. Correlations between relative liver and spleen weights and dose levels were positive but a nega-tive correlation was found between dose levels and serum vitamin E concentration. In female rats, the negative correlations between dose levels and serum iron and triglyceride levels were highly significant. The pathology data showed no remarkable lesions in any of the tissues examined. Results of this study suggest that long-term consumption of high levels of FOCs in rats may reduce serum cholesterol and triglycerides and adversely affect serum iron level and relative liver weight in female rats and relative spleen weights in both sexes.
Disciplinary Categories, Majors, and Undergraduate Academic Experiences: Rethinking Bok’s “Underachieving Colleges” Thesis

Using data from the 2008 University of California Undergraduate Experience Survey, we show that study time and academic conscientiousness were lower among students in humanities and social science majors than among students in science and engineering majors. Analytical and critical thinking experiences were no more evident among humanities and social sciences majors than among science and engineering majors. All three academically beneficial experiences were, however, strongly related to participation in class and interaction with instructors, and participation was more common among humanities and social sciences students than among science and engineering students. Bok’s (Our underachieving colleges: A candid look at how much students learn and why they should be learning more. Princeton and Oxford: Princeton University Press, 2006) influential discussion of “underachievement’ in undergraduate education focused on institutional performance. Our findings indicate that future discussions should take into account differences among disciplinary categories and majors as well.
A new data aggregation scheme via adaptive compression for wireless sensor networks

Data aggregation is necessary for extending the network lifetime of wireless sensor nodes with limited processing and power capabilities, since energy expended in transmitting a single data bit would be at least several orders of magnitude higher when compared to that needed for a 32-bit computation. Therefore, in this article, a novel nonlinear adaptive pulse coded modulation-based compression (NADPCMC) scheme is proposed for data aggregation in a wireless sensor network (WSN). The NADPCMC comprises of two estimators—one at the source or transmitter and the second one at the destination node. The estimator at the source node approximates the data value for each sample. The difference between the data sample and its estimate is quantized and transmitted to the next hop node instead of the actual data sample, thus reducing the amount of data transmission and rending energy savings. A similar estimator at the next hop node or base station reconstructs the original data. It is demonstrated that repeated application of the NADPCMC scheme along the route in a WSN results in data aggregation. Satisfactory performance of the proposed scheme in terms of distortion, compression ratio, and energy efficiency and in the presence of estimation and quantization errors for data aggregation is demonstrated using the Lyapunov approach. Then the performance of the proposed scheme is contrasted with the available compression schemes in an NS-2 environment through several benchmarking datasets. Simulation and hardware results demonstrate that almost 50p energy savings with low distortion levels below 5p and low overhead are observed when compared to no compression. Iteratively applying the proposed compression scheme at the cluster head nodes along the routes over the network yields an additional improvement of 20p in energy savings per aggregation with an overall distortion below 8p.
Treatment of symptomatic convergence insufficiency with a home-based computer orthoptic exercise program.

Purpose To determine the efficacy of a home-based computer orthoptic program to treat symptomatic convergence insufficiency. Methods A retrospective review of consecutive patients with symptomatic convergence insufficiency treated with a home-based computer orthoptic program was performed. Symptomatic convergence insufficiency was defined as: near point of convergence (NPC) >6 cm, decreased positive fusional vergence, exophoria at near at least 4 Δ greater than at far, and documented complaints of asthenopia, diplopia, or headaches with reading or near work. The Computer Orthoptics CVS program was used for this study. Before beginning the computer orthoptic program, patients with an NPC >50 cm were given 4 base-in prisms and push-up exercises (NPC exercises with an accommodative target) for 2 weeks. Results A total of 42 patients were included. Mean treatment duration was 12.6 weeks; mean follow-up, 8.5 months. Of the 42 patients, 35 were treated with the home-based computer orthoptic program and push-up exercises; the remaining 7 only used the computer orthoptic program. Because of a remote NPC, 5 patients were given base-in Fresnel prism before starting treatment. Baseline mean NPC was 24.2 cm; posttreatment mean NPC improved to 5.6 cm: 39 patients (92.8%) achieved an NPC of ≤6 cm ( p Δ . A total of 27 patients (64.2%) reported resolution of symptoms after treatment. Conclusions In our study, home-based computer orthoptic exercises reduced symptoms and improved NPC and fusional amplitudes. The computer orthoptic program is an effective option for treating symptomatic convergence insufficiency.
The influence of size on the response of melanophores in the fiddler crab, Uca pugilator, to eyestalk extracts

1. The influence of size on the response of melanophores in Uca pugilator from Alligator Point, Florida and West Falmouth, Massachusetts was determined. 2. For the first time evidence is presented to indicate that the melanin-dispersing response evoked in eyestalkless crabs after injection of eyestalk extract increases with increase in the size of the crabs used in the assay. 3. The blood of small crabs has a higher titer of melanin-concentrating substance than does the blood of large crabs. Consequently smaller crabs would be more readily able to antagonize injected melanin-dispersing hormone, resulting in a smaller response. In addition, it is possible that the sensitivity of the chromatophores may increase with increase in size of the crab.
Effects of fluid turbulence on phase distortion

A loss of beam intensity occurs when a laser beam is propagated through shear layers with optical index fluctuations. A new model which uses Fraunhofer diffraction around a sinusoidal phase grating predicts the loss of intensity accurately. The size of coherent structures within the shear layers determines the spacing and the width of the grating. Numerical results agree well with previous experimental results.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Computational experience with parallel mixed integerprogramming in a distributed environment

Numerical experiments for a parallel implementation of a branch‐and‐bound mixed 0/1integer programming code are presented. Among its features, the code includes cutting‐planegeneration at the root node, and employs a new branching‐variable selection rulewithin the search tree. The code runs on a loosely‐coupled cluster of workstations usingTreadMarks as the parallel software platform. Numerical tests were performed on all mixed0/1 MIPLIB instances as well as two previously unsolved MIP instances, one arising fromtelecommunication networks and the other a multicommodity flow problem.
Colonization and sanitation in urban Africa: A logistics analysis of the availability of central sewerage systems as a function of colonialism

Abstract The stock of public infrastructure inherited from the colonial era constitutes a strong predictor of the development profiles of African countries. The question that remains to be adequately addressed relates to factors that determine the presence or absence of such infrastructure in the first place. The study reported here employed a logistic analysis in an attempt to answer this question. Colonialism, operationalized in terms of duration of colonial experience, government share of real GDP per capita, and colonizer identity, is posited as a valid predictor of the availability of sanitation infrastructure. The hypothesis is supported by empirical evidence. It is shown that, the availability of central sewerage systems in cities within any African country depends on how long the country was colonized. Colonizer identity, operationalized in terms of the nationality of a colonial power, however, proved to have no predictive ability.
The active surface species in alkali-catalyzed carbon gasification : phenolate (C-O-M) groups vs clusters (particles)

The activities and catalytic roles of different species of potassium in the gasification reactions of graphite by H2O and CO2 are investigated. TEM techniques are used to measure the rates of monolayer edge recession (uncatalyzed and COK catalyzed) and rates of monolayer channeling (catalyzed by particles) on the basal plane of graphite reacting with 21 Torr H2O at 700°C. The turnover frequencies for carbon gasification are: 0.08 s−1 (uncatalyzed), 0.15 s−1 (catalyzed by COK groups), and 7.8 s−1 (catalyzed by particles). Thus the particles have a high activity, whereas the COK groups have only a small activity. TGA and literature results using mixtures of carbon and alkali salts show a sigmoidal dependence of gasification rates on catalyst loading. This is the result of catalyst dispersion and competition between the COK groups and alkali particles. A CNDO semi-empirical molecular orbital calculation is performed on model graphite substrates with -O and -OK groups bonded to the {101l} zigzag face and {112l} armchair face. On the zigzag face, the carbon atom bridging two COK groups gains a large negative charge (−0.486) and hence is a favorable site for binding an O atom. The surface CC bonds in this structure are substantially weakened by adding O atoms on the bridging C atoms, leading to CO release. The O atoms are supplied by the dissociation of H2O and CO2. The possible reason for the alkali particles being more active than the COM (where M = alkali) groups is that the particles can dissociate H2O and CO2 at higher rates, by providing either more active sites or higher activities. The CNDO results also predict that the COK groups have an inhibiting effect on the armchair face; an inhibiting effect has indeed been observed earlier in our laboratory.
Experimental Test Results for Vibration of a High Speed Diesel Engine Turbocharger

Diesel engine turbochargers are known to have operation into the self-excited unstable region. The operation in the nonlinear limit cycle has been tolerated on most applications to date. The need for a quieter and a smoother operation and in addition reduced emission levels have prompted new evaluations of the rotor bearing design for these systems. In this research, a commercial rotor-bearing dynamics computer program was used to evaluate the stability and transient response of a high-speed diesel engine turbocharger. Various models with varying bearing designs and properties were solved to obtain the linear stability threshold speeds and also the nonlinear transient response. The predicted whirl speed map shows two modes of instability and is very similar to recent on-engine test results conducted at Virginia Tech as part of a recent senior capstone design project. The development of the diesel engine test stand and the associated data acquisition system will be discussed. The results from the unloaded ...
Chromium as an industrial carcinogen : Part I

Successive cohorts by year of hire at the same chromate plant (1931-1932, 1933-1934, 1935-1937) and the combined cohort (1931-1937) of 332 employees were followed through 1993. A total of 283 deaths (85%) of the total cohort were identified. In the combined cohort (1931-1937), 66 lung cancers were found, constituting 23.3% of all deaths and 64.7% of all cancers. The lung cancer mortality rates are shown over a span of decades, from 15 years to over 55 years, with progressive rise. Observations of lung cancer identified, employees not found, and cancer risk by age at hire are cited. Lung cancer death rates increased by gradient level of exposure to insoluble (trivalent) chromium and to soluble (hexavalent) chromium, with a pattern of increase by total chromium. Age-specific death rates for lung cancer according to the same gradient exposure range for total, insoluble, and soluble chromium are presented. The potential cancer risk extends to all forms of chromium and to total chromium. Am. J. Ind. Med. 31:129–139, 1997. © 1997 Wiley-Liss, Inc.
Interrelationships of bone ash and whole bone properties in the lactating and parous rat.

Several investigators have studied the mechanical properties of long bones of rats and have found that bone strength may be associated with bone mineral content. In this study we examined further the interrelationships of whole bone properties and bone ash weight of the rat femur. Using a 3-point bending test, the bones were evaluated during lactation and after one to three pregnancy— lactation periods—experiments in which bone ash was significantly reduced. A relationship was established between the time of lactation and the ash weight, stiffness, strength, and toughness but not the ductility. Using all of the experimental data, a highly significant relationship was observed between ash weight and stiffness. A similar significant correlation was revealed between bone ash and strength or toughness, although drawing individual lines for each experiment rather than a common line for all the experiments appeared more appropriate. Given the inherent inaccuracies in the material property measurements of bone, the results suggest that routine measurements of whole bone properties provide an important and sensitive way to evaluate bone quality and that these properties correlate significantly with the bone ash weight.
Acidosis protects against lethal oxidative injury of liver sinusoidal endothelial cells.

The purposes of this study were to determine the pH dependence of lethal endothelial cell injury during oxidative stress and the pH dependence of those cellular mechanisms proposed to result in endothelial cell killing. Oxidative stress was produced in rat liver sinusoidal endothelial cells with H2O2 (5 mmol/L). Cell survival was dependent on the extracellular pH. Indeed, after 180 min of incubation with H2O2, cell survival was only 27% at pH 7.4,45% at pH 6.8 (p <0.05) and 62% at pH 6.4 (p <0.05). Despite improved cell survival at pH 6.4 compared with pH 7.4, the magnitude of ATP hydrolysis and glutathione depletion was similar. In contrast to cell survival, lipid peroxidation as measured by malondialdehyde generation was increased twofold at pH 6.4 compared with pH 7.4. A rapid and profound loss of the the mitochondrial membrane potential occurred during oxidative stress at pH 7.4 that was delayed at pH 6.4 (0.3% vs. 20% of the initial value at 30 min, p <0.0001). After 60 min of incubation with H2O2, NAD(P)H oxidation was greater at pH 7.4 than at pH 6.4 (100% vs. 64%, p <0.05). The results indicate that the protective effect of acidosis against cell death during oxidative stress is associated with the inhibition of NAD(P)H oxidation and delayed loss of the mitochondrial membrane potential. Acidosis appears to maintain organelle and cell integrity during oxidative stress by influencing the redox status of NAD(P)H. (HEPATOLOGY 1991;14:150–157.)
The Development of Referential Communication and Autism Symptomatology in High-Risk Infants

Non-verbal referential communication is impaired in children with Autism Spectrum Disorders (ASD). However, the development of difficulties with referential communication in the younger siblings of children with ASD (High-Risk Siblings)-and the degree to which early referential communication predicts later autism symptomatology-is not clear. We modeled the early developmental trajectories of three types of referential communication: responding to joint attention (RJA), initiating joint attention (IJA), and initiating behavioral requests (IBR) across 8, 10, 12, 15, and18 months of age in High-Risk Siblings (n = 40) and the infant siblings of children without ASD (Low-Risk Siblings; n = 21). Hierarchical Linear Modeling indicated that High-Risk Siblings exhibited lower levels of baseline RJA and IJA and a lower rate of linear change in IBR than Low-Risk Siblings. When the 10 High-Risk Siblings who received an ASD diagnosis were excluded from analyses, group differences in the development of referential communication remained significant only for RJA. Baseline levels of IJA were associated with later ASD symptomatology among High-Risk Siblings, suggesting that individual differences in referential communication development at 8 months may index early manifestations of ASD.
In vivo multisite oximetry using EPR–NMR coimaging

Coimaging employing electron paramagnetic resonance (EPR) imaging and MRI is used for rapid in vivo oximetry conducted simultaneously across multiple organs of a mouse. A recently developed hybrid EPR-NMR coimaging instrument is used for both EPR and NMR measurements. Oxygen sensitive particulate EPR probe is implanted in small localized pockets, called sites, across multiple regions of a live mouse. Three dimensional MRI is used to generate anatomic visualization, providing precise locations of implant sites. The pO₂ values, one for every site, are then estimated from EPR measurements. To account for radio frequency (RF) phase inhomogeneities inside a large resonator carrying a lossy sample, a generalization of an existing EPR data model is proposed. Utilization of known spectral lineshape, sparse distribution, and known site locations reduce the EPR data collection by more than an order of magnitude over a conventional spectral-spatial imaging, enhancing the feasibility of in vivo EPR oximetry for clinically relevant models.
Chemotherapy and its evolving role in the management of advanced prostate cancer

Advanced prostate cancer has been recognized as being responsive to androgen deprivation since the 1940s when Charles Huggins first described the role of surgical castration in managing these patients. However, androgen deprivation only results in transient disease control for the vast majority of men, with those progressing in spite of castrate testosterone levels labeled as having castrate-resistant prostate cancer (CRPC). Until 2004, the therapeutic arena for these patients had remained stagnant, with no agent having shown a survival gain in the CRPC setting. Two landmark publications changed the prostate cancer treatment landscape by providing 'level-1 evidence' that docetaxel-based chemotherapy led to prolongation in overall survival (OS). This was followed by the approval of cabazitaxel in 2010 on the basis of Phase III data demonstrating its efficacy in patients pretreated with docetaxel. More recently, a number of next-generation androgen-directed agents (e.g. abiraterone and enzalutamide) have also been shown to lead to a survival benefit in men with CRPC. With so many new treatment options available, a number of questions remain. These include: how to best sequence chemotherapy with these newer hormonal agents, the clinical implication of cross-resistance between taxanes and androgen-directed agents and which subsets of patients may benefit most from early use of chemotherapy. This review will provide an overview of the evolving role of chemotherapy in the management of advanced prostate cancer in the current era.
Talking to patients with fibromyalgia about physical activity and exercise.

PURPOSE OF REVIEW: The purpose of this article is to describe the application of basic exercise principles to individuals with fibromyalgia to encourage clinicians to discuss with their patients ways of becoming more physically active. RECENT FINDINGS: The goals of increased physical activity and exercise for individuals with fibromyalgia are to improve or maintain general fitness, physical function, emotional well being, symptoms and overall health, and provide them with a feeling of control over their well being. Describing ways of increasing activity through home, work and leisure-related tasks or exercise provides a universal approach to increasing physical activity that applies to individuals with fibromyalgia and fits a counseling model of health behavior familiar to clinicians. The patient-clinician relationship provides a unique opportunity for health professionals to counsel individuals with fibromyalgia to become and remain more physically active. SUMMARY: Regular physical activity and exercise has numerous physical, psychological, and functional benefits for individuals with fibromyalgia and should be included in treatment plans. Clinicians can help patients adopt a more physically active lifestyle through targeted discussions, support and consistent follow up.
Developing facilitators for faculty learning communities

The processes for choosing, preparing, and supporting facilitators for faculty learning communities are as unique as the campuses housing them. This chapter reports on a range of activities and highlights three preparation programs.
The masks of validity: a deconstructive investigation

Postpositivists, such as Mishler (1990) and Lincoln and Guba (1985), have commonly claimed that there are substantial methodological and epistemological differences between their framework and that of the conventional or positivistic approach. On the face of it, this claim is indisputable. For example, Lincoln and Guba in Naturalistic Inquiry (1985) lay out five key differences in terms of ontology, epistemology, generalizability, causality, and axiology (p. 37). In contrast, it is argued here, as a result of a deconstructive investigation, that the conventional approach and more radical versions of postpositivism are, in a primary way, profoundly and disturbingly similar. This point is pursued by investigating the transgressive practices of validity across both conventional and more radical postpositivist research orientations and ends with new imaginaries of validity that make problematic conventional and postpositivist validity practices and celebrate the play of multiplicity and difference.
A bioinspired redox relay that mimics radical interactions of the Tyr–His pairs of photosystem II

In water-oxidizing photosynthetic organisms, light absorption generates a powerfully oxidizing chlorophyll complex (P680(•+)) in the photosystem II reaction centre. This is reduced via an electron transfer pathway from the manganese-containing water-oxidizing catalyst, which includes an electron transfer relay comprising a tyrosine (Tyr)-histidine (His) pair that features a hydrogen bond between a phenol group and an imidazole group. By rapidly reducing P680(•+), the relay is thought to mitigate recombination reactions, thereby ensuring a high quantum yield of water oxidation. Here, we show that an artificial reaction centre that features a benzimidazole-phenol model of the Tyr-His pair mimics both the short-internal hydrogen bond in photosystem II and, using electron paramagnetic resonance spectroscopy, the thermal relaxation that accompanies proton-coupled electron transfer. Although this artificial system is much less complex than the natural one, theory suggests that it captures the essential features that are important in the function of the relay.
The diagnosis of hysterical personality disorder: A study of attitudes

Abstract The concept of personality disorder must, as other psychiatric diagnoses, be evaluated in terms of reliability, utility, and validity. In recent years, there has been growing interest in such issues for personality diagnoses in general1,2 and for obsessive-compulsive,3–6 antisocial,7 and hysterical personality disorders in particular. Since these diagnoses rest on the judgment that an individual is deviant in respect of traits shared to a greater or lesser degree by everyone, the diagnostic process itself, the exercise whereby that judgment is made, should receive particular study. In this way, we might learn which clinical features can be reliably recognized and, thus, used to form the basis for operational definitions of personality disorders. As an initial step in such research, a group of psychiatrists was asked to comment on several factors important in the diagnosis of hysterical personality disorder.
Uterine Leiomyosarcoma and Endometrial Stromal Sarcoma: Lymph Node Metastases and Sites of Recurrence

Abstract This study was undertaken to examine the incidence and conditions under which lymph node metastases are present and patterns of recurrence in women with uterine leiomyosarcoma (LMS) and endometrial stromal sarcoma (ESS), excluding malignant mixed mesodermal tumors. From 1981 through 1991, 21 women with LMS and 10 women with ESS were treated. Retroperitoneal lymph node dissections were performed in 15 women with LMS and 7 women with ESS. In the women with LMS, 4/15 (26.7%) had lymph node metastases; in each there was disseminated intra-abdominal disease. In the 7 women with ESS, there were no lymph node metastases present. Ten women (47%) with LMS developed recurrences, and 3 (14%) had persistent disease. In the 10 women with ESS, 3 (30%) had recurrences, and 1 (10%) had persistent disease. In total, recurrences involved the lung in 84% of cases. Of the 13 women with recurrences, 7 had undergone lymph node sampling, and all were negative; 4 additional women had no evidence of adenopathy on abdominal-pelvic CT scan. Lymph node metastases were found only with extrauterine disease, and in all of these cases there was rapid progression of the sarcoma. Women without extrauterine disease did not have lymph node metastases detected; however, there was still a high rate (40%) of distant failure. Knowledge of lymph node status has minimal impact on the clinical management of women with uterine LMS and ESS.
Thermal Conductivity Measurements of Nylon 11-Carbon Nanofiber Nanocomposites

Carbon nanofibers (CNFs) were incorporated into nylon 11 to form nylon 11-carbon nanofiber nanocomposites via twin screw extrusion. Injection molding has been employed to fabricate specimens that possess enhanced mechanical strength and fire retardancy. The thermal conductivity of these polymer nanocomposites was measured using a guarded hot plate method. The measurement results show that the room temperature thermal conductivity increases with the CNF loading from 0.24±0.01 W/m K for pure Nylon 11 to 0.30±0.02 W/m K at 7.5 wt % CNF loading. The effective medium theory has been used to determine the interface thermal resistance between the CNFs and the matrix to be in the range of 2.5―5.0×10 ―6 m 2 K/W from the measured thermal con ductivity of the nanocomposite.
A record of estuarine water contamination from the Cd content of foraminiferal tests in San Francisco Bay, California

A five-year dissolved Cd time series from San Francisco Bay and adjacent coastal water shows that the composition of surface water towards the mouth of the estuary is determined largely by the effect of coastal upwelling. Cd concentrations inside and outside the estuary Ž0.2–1.0 nmolrkg. increase as Cd-rich deep water is advected to the surface near the coast during spring and summer. On average, the mean Cd concentrations inside San Francisco Bay Ž0.54 nmolrkg. during 1991–1995 was significantly higher than outside Ž0.35 nmolrkg , however. Surface samples collected throughout San . Francisco Bay confirm an internal Cd source unrelated to river discharge. The Cd content of the test of a benthic foraminifer Ž Elphidiella hannai . in a dated sediment core from San Francisco Bay was measured to determine if the water column Cd enrichments in San Francisco Bay could be related to the rapid development of the watershed. The method is based on the observation that the CdrCa ratio of carefully cleaned tests of foraminifera is determined by the dissolved Cd content of overlying water at the time of test formation. Pre-industrial foraminiferal CdrCa ratios in the sediment core average 274 " 15 nmolrmol Ž n s 19. nmolrmol. Foraminiferal CdrCa ratios increased to 386 " 33 nmolrmol Ž n s 19. over the past several decades indicating a 40% increase in the mean Cd content of surface water in Central San Francisco Bay. We suggest that, in addition to Cd discharges into the estuary, indirect consequences of agricultural development in the Central Valley of California could have contributed to this increase. This new method to reconstruct estuarine contamination is not affected by some of the processes that complicate the interpretation of changes in bulk sediment metal concentrations. q 1999 Elsevier Science B.V. All rights reserved.
Effects of phorbol esters and a diacylglycerol on mouse eggs: Inhibition of fertilization and modification of the zona pellucida

Sperm penetration of the zona pellucida and fertilization are inhibited in mouse eggs treated with phorbol esters and the diacylglycerol, sn-1,2-dioctanoyl glycerol. The effect appears mediated by the zona pellucida, since zona-free eggs treated with these compounds are fertilized to the same extent as untreated eggs. Moreover, the binding of sperm to isolated zonae incubated in the absence or presence of biologically active phorbol esters is similar. Last, sperm treated with phorbol esters or sn-1,2-dioctanoyl glycerol bind to eggs and undergo the acrosome reaction to the same extent as untreated sperm. The inhibitory effect on fertilization is correlated with an egg-induced modification of at least ZP2, as manifested by a change in its electrophoretic mobility in polyacrylamide gels. In addition, changes in the biological properties of the treated zonae occur, such that sperm binding is not altered, but that the final stage(s) of the zona-induced acrosome reaction is inhibited. Zonae obtained from phorbol ester- or diacylglycerol-treated eggs should provide a system to study both the structural modifications of the zona proteins that are involved in induction of the acrosome reaction, as well as, delineating the sequence of events that comprise the acrosome reaction.
Physiology and chemistry of the hypothalamic releasing factors for gonadotropins: a new approach to fertility control.

Abstract A short review of the concepts of hypothalamic control of adenohypophysial secretions with particular reference to the gonadotropins — How the hypothalamic releasing factors were isolated and characterized — Molecular structure of the LH-releasing factor — Its effects on the secretion of LH and FSH — Its triggering of ovulation — Synthetic polypeptides antagonists to LH-releasing factor as a new approach to fertility control.
Home Ownership Crime and the Tipping and Trapping Processes

The central purpose of this article is to examine the causal relationship between the percentage of homeowners in a neighborhood and city and crime rates. A cross-lag analysis is used for the years...
Do psychology researchers tell it like it is? A microgenetic analysis of research strategies and self-report accuracy along a continuum of expertise

Acquiring research skills is considered to be a highly challenging aspect of developing expertise in the social sciences. Because instruction and mentoring in these skills are typically grounded in the self-report of researchers, difficulties in learning the material may be due to the content and accuracy of these explanations. Using a mixed-method, microgenetic design, this study examines the explanations of problem-solving processes by researchers along a continuum of expertise during simulated experiment design and subsequent data analysis. Findings indicate that participants’ self-explanations are largely inaccurate. Further, frequency of inaccurate statements is positively associated with the frequency of abstract cognitive processes, such as mental modeling and situation assessment. Implications of these findings for instruction and future research directions are discussed.
The significance of shear stress in the agglomeration kinetics of fractal aggregates

Abstract The aggregation kinetics of fully destabilized colloidal hematite particles under conditions of varying laminar shear stress were investigated. Particle size distributions were measured over time, which allowed for a mechanistic evaluation of various aggregate–aggregate interaction rates. It was observed experimentally that large aggregates react rapidly with sub-micron size fractions under conditions of an applied shear stress; Brownian motion appears to dominate interactions only at early times when a monomodal size distribution exists. It was hypothesized that collisions between dissimilar sized aggregates are favored under laminar shear conditions. The experimental results also suggest that hydrodynamic influences are less important when porous, fractal aggregates are interacting than in interactions between impermeable spheres.
Monosaccharides are not detected in whole or isthmic bovine oviductal fluid collected throughout the estrous cycle, as analyzed by HPLC.

Abstract In the bovine oviduct, monosaccharides may play a role in the preparation of gametes for fertilization. Sperm are sequestered in the isthmic region of the oviduct where capacitation, requisite biochemical changes in sperm membranes, may take place. Retention of spermatozoa in the oviductal isthmus is dependent on a carbohydrate recognition system between oviductal epithelium and sperm membrane lectins. The monosaccharide, fucose, has been found to be important to this recognition system. However, both gametes and epthelium are also bathed in oviductal fluid (ODF), and fucose or other monosaccharides may be constituents of ODF and so may be important to sperm binding to oviductal epithelium and subsequent preparation for fertilization. In this study, ODF from dairy cows was analyzed by HPLC for the presence of 5 monosaccharides (fucose, galactose, glucosamine, mannose and xylose). Both whole ODF, collected by cannulation of the entire oviduct of 1 cow over a complete estrous cycle, and regional staged ODF, collected and pooled from 13 cows from the isthmic region only at estrus, were analyzed. We report negligible concentrations of all 5 monosaccharides in both types of ODF analyzed. Because the detection limit of our assay was 10 8 times lower than fucose concentrations found to be physiologically important in earlier in vitro studies, we conclude that bovine ODF does not contain physiologically active levels of free fucose or other, similar monosaccharides at any time of the estrous cycle.
Hospital assessments of children with learning problems: perspectives from special education administrators and hospital evaluators.

Background.—The schooling of 1 of every 8 children is influenced by the Individuals with Disabilities Education Act (IDEA). The IDEA also governs, to a degree, the relationship between interdisciplinary hospital clinics that evaluate many of these children and the schools that provide educational services. Little is known about how this relationship functions or how educational personnel perceive reports from hospital settings. Objectives.—To describe special education administrator and hospital evaluator perspectives on hospital assessments of children with learning problems. Methods.—A survey of attendees at a 1998 meeting of the Massachusetts Association of Special Education Administrators was conducted by use of a questionnaire using closed and open-ended questions. Subsequently, focus groups were held with hospital evaluators. Results.—Special education administrators describe a high level of frustration with hospital-school relations. They state that hospital reports do not meet the needs of children in the educational setting. They seek closer collaboration with medical evaluators. Evaluators working in hospital settings acknowledge frustration perceived by school personnel. They state that communication with educational personnel improves the quality of their reports and outcomes for the child. Conclusions.—Hospital assessments of children with learning problems are associated with high levels of frustration among special education administrators. These assessments might be made more useful if careful attention were paid to the needs of educators. Greater communication between hospital evaluators and school personnel may increase the usefulness of hospital clinic assessments of children with learning problems.
Challenges and dangers of reporting in a tumultuous border region: how journalists at the El Paso Times deal with the violence in neighboring Ciudad Juarez

Journalists at the El Paso Times routinely cover violence in neighboring Ciudad Juarez, where thousands of men, women, and children have been murdered in recent years. Utilizing border theory and research involving journalists and trauma, this qualitative newsroom study examines how journalists at the El Paso Times are dramatically affected by their daily exposure to the unrelenting violence in this border region. The study recommends that newsroom management provide journalists with the necessary resources and support that will help them cope. Language: en
Factors influencing temporal effects with notched-noise maskers

Abstract Temporal effects in simultaneous masking were studied by measuring the reduction in the amount of masking produced by a gated masker when that masker was preceded hy a 400-ms noise (the precursor) that was usually spectrally identical to the masker The signal frequency (fs) was 1 0 or 4 0 kHz. Experiment 1 revealed a temporal effect only when there was a spectral notch (centered at fs) in the masker and precursor. For a relative nolchwidth of 0 4 fs, the temporal effect was larger at 4 0 than at 1 0 kHz. In experiment 2, where the masker and precursor both consisted of two bands of noise separated by a spectral notch of 0 4 fs, the size of the temporal effect remained essentially constant as the bandwidth of these noise bands increased from 0 2–0 8 kHz. The results from experiment 3 indicated that the temporal effect was largest when the level of the precuisor was equal to the level of the masker. Finally, the results from experiment 4 suggested that the temporal effect may depend upon the frequency region below as well as above fs, but that the frequency region above ts is probably more important.
Arterial pulse wave analysis: An accurate means of determining cardiac output in children.

OBJECTIVE Cardiac output is a useful measure of myocardial performance. Standard methods of determining cardiac output are not without risk and can be problematic in children. Arterial pulse wave analysis (PulseCO), a novel, minimally invasive cardiac output determination technique, offers the advantage of continuous monitoring, convenience, and low risk. This technique has not been validated in children. The purpose of this study was to validate PulseCO as an accurate means of noninvasively determining real-time cardiac output in children. DESIGN Prospective, single-center evaluation. SETTING Children's hospital. PATIENTS Any child with a structurally normal heart, undergoing hemodynamic evaluation in the cardiac catheterization laboratory, was included. INTERVENTIONS A prograde right heart catheterization was performed, and cardiac output was determined using the thermodilution technique, via placement of a pulmonary arterial catheter. MEASUREMENTS AND MAIN RESULTS Thermodilution results were compared with continuous real-time cardiac output measurements obtained with the PulseCO system, and they were then analyzed by standard correlation techniques and Bland-Altman analysis. Twenty patients were evaluated with a median age of 10.5 yrs and a median weight of 25 kg. The mean thermodilution cardiac index was 3.3 +/- 0.9 L/min/m, whereas the mean PulseCO cardiac index was 3.1 +/- 0.9 L/min/m. Standard Pearson correlation tests revealed a correlation coefficient of .94 (p < .001). Bland-Altman analysis revealed excellent clinical agreement with a mean difference of 0.19 L/min/m and a precision of 0.28 L/min/m at 2 sd. CONCLUSIONS Arterial pulse wave analysis by the PulseCO system provides a novel, minimally invasive method of determining real-time cardiac output in children.
Diagnosis and management of the patulous eustachian tube.

Objective The patulous eustachian tube (ET) seems to be caused by a longitudinal concave defect in the mucosal valve at the superior aspect of its anterolateral wall and causes troublesome autophony of one's own voice and breathing sounds. Patulous ET reconstruction was evaluated to analyze whether submucosal graft implantation to fill in the concavity within the patulous tubal valve may produce lasting relief of symptoms. Study design Prospective trial. Setting Tertiary referral center, ambulatory surgery. Patients Fourteen ETs in 11 adults with 1 or more years of confirmed continuous patulous ET symptoms refractory to medical care. Intervention Endoluminal patulous ET reconstruction was performed in 14 separate cases using a combined endoscopic transnasal and transoral approach under general anesthesia. A submucosal flap was raised along the anterolateral wall of the tubal lumen up to the valve and mobilized superiorly off of the basisphenoid. The pocket was filled with autologous cartilage graft or Alloderm implant, restoring the normal convexity and competence to the mucosal lumen valve. Main outcome measure Autophony symptoms were scored as 1) complete relief; 2) significant improvement, satisfied; 3)significant improvement, dissatisfied; 4) unchanged; or 5)worse. Results All 14 cases reported immediate complete relief of autophony. Results with an average follow-up of 15.8 months are as follows: 1 (7%) case had complete relief; 5 (36%) had significant improvement, satisfied; 7 (50%) had significant improvement, dissatisfied; and 1 (7%) was unchanged. There were no complications. Correlation between patulous ET and other conditions was strongest with previous tubal dysfunction. Autophony of voice, but not breathing sounds, was also found to be experienced by 17 (94%) of 18 patients with superior semicircular canal dehiscence syndrome and could be easily mistaken for patulous ET autophony. Conclusion Patulous ET seems to be caused by a concave defect in the tubal valve's anterolateral wall. Submucosal graft implantation to restore the normal convexity to the valve wall seems to provide lasting relief of symptoms. Long-term study is needed. It is important to differentiate between the autophony of semicircular canal dehiscence syndrome and patulous ET.