bluuebunny/crossref_metadata_2025_split huggingface dataset:
A modified Girard derivatizing reagent for universal profiling and trace analysis of aldehydes and ketones by electrospray ionization tandem mass spectrometry
Authors: Johnson David W. 
Published: August 2007

Abstract4‐Hydrazino‐N,N,N‐trimethyl‐4‐oxobutanaminium iodide (HTMOB) is a modified Girard derivatizing reagent synthesized to improve the sensitivity of analysis of aldehydes and ketones with electrospray ionization tandem mass spectrometry. Compared with Girard T reagent the measured signal intensity increase is between 3.3 times (succinylacetone) and 7.0 times (17‐hydroxyprogesterone). HTMOB is a universal profiling reagent for aldehydes and ketones. A neutral loss of 59 Da scan detects all aldehydes and ketones from acetone to corticosteroids. Applications described include the profiling of ketones, ketoacids and ketodiacids in the urine of children with ketosis and the profiling of long‐chain aldehydes incorporated in plasma plasmalogens. Copyright © 2007 John Wiley & Sons, Ltd.
Quality Improvement of Environmental Secondary Electron Detector Signal Using Helium Gas in Variable Pressure Scanning Electron Microscopy
Authors: Oho Eisaku , Suzuki Kazuhiko , Yamazaki Sadao 
Published: August 2007

AbstractThe quality of the image signal obtained from the environmental secondary electron detector (ESED) employed in a variable pressure (VP) SEM can be dramatically improved by using helium gas. The signal‐to‐noise ratio (SNR) increases gradually in the range of the pressures that can be used in our modified SEM. This method is especially useful in low‐voltage VP SEM as well as in a variety of SEM operating conditions, because helium gas can more or less maintain the amount of unscattered primary electrons. In order to measure the SNR precisely, a digital scan generator system for obtaining two images with identical views is employed as a precondition. SCANNING 29: 225‐229, 2007. © 2007 Wiley Periodicals, Inc.
Managing development in the hillsides of Trinidad and Tobago using geoinformatics
Authors: Baban Serwan M. J. , Thomas Deborah , Canisius Francis , Sant Kamal J. 
Published: August 2007

AbstractAn increase in the unmanaged development of hillsides is causing environmental, social and economic problems in Trinidad and Tobago. Improved environmental awareness and deepening environmental concerns in recent years have focused attention on the need to move towards a more sustainable pattern of development. Scientific criteria for managing hillside development do not seem to exist and attempts in this regard are seriously compromised amongst other things by the lack of effective and reliable information base for decision making, i.e. information poverty. This paper advances a geoinformatics based methodology for determining suitability for built development on hillsides and to develop and implement a simple scientific criterion strategy for managing hillside development in Trinidad and Tobago whilst enduring information poverty. Additionally, a case study is presented to highlight the applicability of the concept to Tobago. The results showed all potential areas suitable for hillside development in Tobago and also identified areas not suitable and the reason(s) for disqualifying these areas. The proposed approach is adaptable, scientifically justifiable and open to scrutiny, and will lend itself to public acceptance. Copyright © 2007 John Wiley & Sons, Ltd and ERP Environment.
An application of mixture distributions in modelization of length of hospital stay
Authors: Atienza N. , García‐Heras J. , Muñoz‐Pichardo J. M. , Villa R. 
Published: August 2007

AbstractLength of hospital stay (LOS) is an important indicator of the hospital activity and management of health care. The skewness exhibited by this variable poses problems in statistical modeling. The aim of this work is to model the variable LOS within diagnosis‐related groups (DRG) through finite mixtures of distributions. A mixture of the union of Gamma, Weibull and Lognormal families is used in the model, instead of a mixture of a unique distribution family. Some theoretical questions regarding the model, such as the identifiability and study of asymptotic properties of ML estimators, are analyzed. The EM algorithm is proposed for performing these estimators. Finally, this new proposed model is illustrated by using data from different DRGs. Copyright © 2007 John Wiley & Sons, Ltd.
Does workload cause work‐home interference or is it the other way around?
Authors: Dikkers Josje S. E. , Geurts Sabine A. E. , Kompier Michiel A. J. , Taris Toon W. , Houtman Irene L. D. , van den Heuvel Floor 
Published: August 2007

AbstractThe present study was designed to investigate the causal relationships between work‐home interference (WHI) and one of its strongest correlates, quantitative workload. Two‐phase longitudinal data (with a 1‐year time lag) were gathered from 828 Dutch police officers. Drawing on the effort‐recovery model, and in line with the current WHI literature, we hypothesized that relatively high workload precedes increased levels of WHI 1 year later (‘normal’ causation). In addition, we tested the alternative hypothesis that relatively high levels of WHI predict increased workload 1 year later (‘reversed’ causation). Results of hierarchical regression analyses showed that workload and WHI have causal and reversed causal relationships across time, supporting both hypotheses (although effect sizes are limited). Accordingly, these findings suggest that workload is not merely an antecedent of WHI but is also a potential consequence. Copyright © 2007 John Wiley & Sons, Ltd.
Thematic continuities: Talking and thinking about adaptation in a socially complex classroom
Authors: Ash Doris 
Published: August 2007

AbstractIn this study I rely on sociocultural views of learning and teaching to describe how fifth–sixth‐grade students in a Fostering a Community of Learners (FCL) classroom gradually adopted scientific ideas and language in a socially complex classroom. Students practiced talking science together, using everyday, scientific, and hybrid discourses as they studied endangered species. Students' overarching content themes, or “thematic continuities,” acted as generative scaffolds for developing complex lines of inquiry, leading ultimately to the appropriation of aspects of the biological principle of adaptation. Thematic continuities provided an organizing framework for thinking and talking about previously disconnected science facts, and set the stage for the adaptationist stance. Mixed method data analyses relied on written assessments, in‐depth guided clinical interviews, video and audiotaping of small and large group participant structures, in‐class student work, and ethnographic notes. Data analysis included two discrete levels, the macro (whole and half class) and the intermediate (case study of one small group) to capture both holistic and detailed aspects of dialogue. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 45: 1–30, 2008
Free‐choice worksheets increase students' exposure to curriculum during museum visits
Authors: Mortensen Marianne F. , Smart Kimberly 
Published: August 2007

AbstractThe museum visit is an important part of elementary school science teaching. However, a divide exists between teachers, who require curricular accountability, and museums, who emphasize free‐choice exploration. Can a carefully constructed worksheet bridge this divide by providing free‐choice exploration of curricular topics during the museum visit? In the present study, a theoretical framework was constructed to inform the design of worksheets as free‐choice learning devices. This framework was used to analyze the design of an existing museum worksheet. Subsequently, curriculum‐related conversations among school groups visiting a museum were monitored in groups supplied with the worksheet and in control groups without. Overall, the worksheet complied well with design criteria synthesized from the free‐choice learning literature. Furthermore, the use of the worksheet increased the number and diversity of curriculum‐related conversations among school groups during the visit. This study documents that the use of carefully designed worksheets may increase students' exposure to curriculum during a museum visit, and thus may help build better bridges between teacher needs and museum free‐choice identities. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 44: 1389–1414, 2007
Classification of chemical reactions: Stages of expertise
Authors: Stains Marilyne , Talanquer Vicente 
Published: August 2007

AbstractIn this study we explore the strategies that undergraduate and graduate chemistry students use when engaged in classification tasks involving symbolic and microscopic (particulate) representations of different chemical reactions. We were specifically interested in characterizing the basic features to which students pay attention when classifying chemical reactions at the symbolic and microscopic levels. We identified the categories that students create when classifying chemical reactions, and compared the performance in simple classification tasks of students with different levels of preparation in the discipline. Our results suggest that advanced levels of expertise in chemical classification do not necessarily evolve in a linear and continuous way with academic training; a significant proportion of undergraduate students, regardless of their level of preparation in chemistry, based their classification schemes on the identification of surface features and failed to create chemically meaningful classes. Students' ability to identify chemically meaningful groups was strongly influenced by their recent learning experiences and their graduate work in chemistry. The level of expertise and the type of chemical representation influenced the number and types of categories created, the nature of the features used to build a class, and the role that these features played during the classification process. Although all of the participants in our study expressed similar levels of unfamiliarity with the microscopic images of chemical reactions, advanced students were more adept at using the available representational features to build chemical meaning. © 2007 Wiley Periodicals, Inc. J Res Sci Teach 45: 771–793, 2008
Behavioral and physiologic responses to environmental enrichment in the maned wolf (Chrysocyon brachyurus)
Authors: Cummings Dawn , Brown Janine L. , Rodden Melissa D. , Songsasen Nucharin 
Published: August 2007

AbstractThe ex situ population of maned wolves is not self‐sustaining due to poor reproduction, caused primarily by parental incompetence. Studies have shown that environmental enrichment can promote natural parental behaviors in zoo animals. The objective of this study was to determine the effects of environmental enrichment on behavioral and physiological responses of maned wolves. During an 8‐week experimental period, daily behavior observations and fecal sample collection were conducted on four adult wolves (2.2) individually housed in environments without enrichment. After 2 weeks, the wolves were chronologically provided with 2‐week intervals of hiding dead mice around the exhibit, no enrichment, and introduction of boomer balls. Responses of the wolves to enrichment were assessed based on activity levels and exploratory rates, as well as the level of corticoid metabolites in fecal samples collected daily throughout the study period. Providing wolves with environmental enrichment significantly increased exploratory behaviors (P<0.05), especially when mice were hidden in the enclosure. Fecal corticoid concentrations were increased during periods of enrichment in males (P<0.05), but not in females. Overall, there were no correlations between behavioral responses to enrichment and fecal corticoid levels. Behavioral results suggest that environmental enrichment elicits positive effects on the behavior of captive maned wolves. There is evidence suggesting that providing animals with ability to forage for food is a more effective enrichment strategy than introducing objects. There is need for a longer term study to determine the impact of environmental enrichment in this species. Zoo Biol 26:331–343, 2007. © 2007 Wiley‐Liss, Inc.
Effects and clinical significance of tetrahydrobiopterin supplementation in phenylalanine hydroxylase‐deficient hyperphenylalaninaemia
Authors: Gramer G. , Burgard P. , Garbade S. F. , Lindner M. 
Published: August 2007

SummaryIn recent years several studies on tetrahydrobiopterin (BH4)‐responsive phenylalanine hydroxylase (PAH) deficiency have been published. The molecular mechanisms of BH4 responsiveness are not conclusively understood, but there is evidence that BH4 responsiveness in hyperphenylalaninaemia (HPA) depends on the patient's genotype and residual PAH activity. As a BH4 preparation will soon obtain marketing approval as an alternative treatment for phenylketonuria (PKU), it is particularly important to evaluate this treatment and to define criteria to identify patients with a potential benefit from it. Most of the patients found to be BH4‐responsive suffered from mild PKU or mild hyperphenylalaninaemia (MHP) and some of these would not be treated at all in many countries. Of patients with moderate and classic forms of PKU, only a few were classified as responders and the clinical significance of the effect size may be small.
Effect of Sterol Carrier Protein‐2 Expression on Sphingolipid Distribution in Plasma Membrane Lipid Rafts/Caveolae
Authors: Atshaves Barbara P. , Jefferson John R. , McIntosh Avery L. , Gallegos Adalberto , McCann Bonnie M. , Landrock Kerstin K. , Kier Ann B. , Schroeder Friedhelm 
Published: August 2007

AbstractAlthough sphingolipids are highly important signaling molecules enriched in lipid rafts/caveolae, relatively little is known regarding factors such as sphingolipid binding proteins that may regulate the distribution of sphingolipids to lipid rafts/caveolae of living cells. Since early work demonstrated that sterol carrier protein‐2 (SCP‐2) enhanced glycosphingolipid transfer from membranes in vitro, the effect of SCP‐2 expression on sphingolipid distribution to lipid rafts/caveolae in living cells was examined. Using a non‐detergent affinity chromatography method to isolate lipid rafts/caveolae and non‐rafts from purified L‐cell plasma membranes, it was shown that lipid rafts/caveolae were highly enriched in multiple sphingolipid species including ceramides, acidic glycosphingolipids (ganglioside GM1); neutral glycosphingolipids (monohexosides, dihexosides, globosides), and sphingomyelin as compared to non‐raft domains. SCP‐2 overexpression further enriched the content of total sphingolipids and select sphingolipid species in the lipid rafts/caveolae domains. Analysis of fluorescence binding and displacement data revealed that purified human recombinant SCP‐2 exhibited high binding affinity (nanomolar range) for all sphingolipid classes tested. The binding affinity decreased in the following order: ceramides > acidic glycosphingolipid (ganglioside GM1) > neutral glycosphingolipid (monohexosides, hexosides, globosides) > sphingomyelin. Enrichment of individual sphingolipid classes to lipid rafts/caveolae versus non‐rafts in SCP‐2 expressing plasma membranes followed closely with those classes most strongly bound to SCP‐2 (ceramides, GM1 > the neutral glycosphingolipids (monohexosides, dihexosides, and globosides) > sphingomyelin). Taken together these data suggested that SCP‐2 acts to selectively regulate sphingolipid distribution to lipid rafts/caveolae in living cells.
The Effects of Simultaneous Administration of Dietary Conjugated Linoleic Acid and Telmisartan on Cardiovascular Risks in Rats
Authors: Abdullah Mohammad M. , Xu Zuyuan , Pierce Grant N. , Moghadasian Mohammed H. 
Published: August 2007

AbstractDietary conjugated linoleic acid (CLA) and the antihypertensive drug, telmisartan, have both been shown to modify cardiovascular risks. The effects of a combination of these two agents have, however, not been investigated. This 20 week study sought to assess the therapeutic potential of a CLA/telmisartan co‐administration in rats fed a high‐fructose high‐fat diet. Thirty‐three male Sprague–Dawley rats were randomly assigned to five experimental groups, including control, losartan, telmisartan, CLA, and CLA + telmisartan‐treated animals. Body weight, blood pressure, and blood levels of lipids, glucose, insulin, and inflammatory markers were measured. Co‐administration of CLA and telmisartan resulted in significant (P < 0.05) reductions in body weight, visceral fat, serum total cholesterol, triglycerides, glucose, plasma insulin concentrations, and systolic blood pressure compared with those in the control group. Moreover, plasma levels of IL1‐α and IFN‐γ were reduced and levels of IL1‐β, IL‐4, IL‐6, and IL‐10, plus TNF‐α were increased in the co‐therapy group, compared with controls. In conclusion, this study suggests that a combination of CLA with telmisartan may modify several risk factors of cardiovascular disease commonly seen in metabolic syndrome. This combination of nutraceuticals and pharmaceuticals may be a safe and cost‐effective strategy in a number of high‐risk subjects. Future studies will further document clinical benefits of such combination therapy.
Dietary Virgin Olive Oil Reduces Oxidative Stress and Cellular Damage in Rat Brain Slices Subjected to Hypoxia–Reoxygenation
Authors: González‐Correa J. A. , Muñoz‐Marín J. , Arrebola M. M. , Guerrero A. , Narbona F. , López‐Villodres J. A. , De La Cruz J. P. 
Published: August 2007

AbstractWe investigated how virgin olive oil (VOO) affected platelet and hypoxic brain damage in rats. Rats were given VOO orally for 30 days at 0.25 or 0.5 mL kg−1 per day (doses A and B, respectively). Platelet aggregation, thromboxane B2, 6‐keto‐PGF1α, and nitrites + nitrates were measured, and hypoxic damage was evaluated in a hypoxia–reoxygenation assay with fresh brain slices. Oxidative stress, prostaglandin E2, nitric oxide pathway activity and lactate dehydrogenase (LDH) activity were also measured. Dose A inhibited platelet aggregation by 36% and thromboxane B2 by 19%; inhibition by dose B was 47 and 23%, respectively. Virgin olive oil inhibited the reoxygenation‐induced increase in lipid peroxidation (57% in control rats vs. 2.5% (P < 0.05) in treated rats), and reduced the decrease in glutathione concentration from 67 to 24% (dose A) and 41% (dose B). Brain prostaglandin E2 after reoxygenation was 306% higher in control animals, but the increases in treated rats were only 53% (dose A) and 45% (dose B). The increases in nitric oxide production (213% in controls) and activity of the inducible isoform of nitric oxide synthase (175% in controls) were both smaller in animals given VOO (dose A 84%; dose B 12%). Lactate dehydrogenase activity was reduced by 17% (dose A) and 42% (dose B). In conclusion, VOO modified processes related to thrombogenesis and brain ischemia. It reduced oxidative stress and modulated the inducible isoform of nitric oxide synthase, diminishing platelet aggregation and protecting the brain from the effects of hypoxia–reoxygenation.
Effect of Dietary Cholesterol and Fat on Cell Cholesterol Transfer to Postprandial Plasma in Hyperlipidemic Men
Authors: Sutherland Wayne H. F. , de Jong Sylvia A. , Walker Robert J. 
Published: August 2007

AbstractPostprandial chylomicrons are potent ultimate acceptors of cell membrane cholesterol and are believed to accelerate reverse cholesterol transport (RCT). We compared the effects of meals rich in polyunsaturated fat (PUFA) and either high (605 mg) or low (151 mg) in cholesterol and a meal rich in dairy fat (DF) in the form of cream on net in vitro transport of red blood cell (RBC) membrane cholesterol to 4 and 6 h postprandial plasma in eight normotriglyceridemic (NTG‐H) and eight hypertriglyceridemic (HTG‐H) men with mild to moderate hypercholesterolemia. In HTG‐H men, cell cholesterol accumulation in 6‐h postprandial plasma was significantly (P = 0.02) less after the PUFA‐HC meal compared with the other meals. The significant (P < 0.001) increase in cell plus endogenous cholesterol accumulation in the triglyceride‐rich lipoprotein (TRL) fraction of 4 h postprandial plasma incubated with RBC was significantly (P = 0.007) higher after the PUFA‐HC meal compared with DF meal in HTG‐H men. In NTG‐H men, cholesterol accumulation in plasma and plasma lipoproteins in the presence and absence of RBC was not significantly affected by the type of meal ingested. These data suggest that addition of large amounts of cholesterol to a PUFA meal may impair diffusion‐mediated transport of cell membrane cholesterol to postprandial plasma and that replacing DF with PUFA in a meal increases postprandial lipemia and may potentially increase cholesterol accumulation in atherogenic postprandial TRL in HTG‐H men.
Effect of Ultrasonication on Droplet Size in Biodiesel Mixtures
Authors: Wu Peng , Yang Ying , Colucci José A. , Grulke Eric A. 
Published: August 2007

AbstractBiodiesel fuels have become more attractive recently because of their environmental benefits and cost competitiveness compared to diesel fuel. Many processing improvements have been proposed to increase the conversion rates and the yields of vegetable oil in order to lower production costs and improve biodiesel product quality. In conventional biodiesel production chemistries, alkaline transesterifications of alcohol/oil dispersions should occur primarily near the interface. Ultrasonic mixing has already been shown to increase overall conversion rates for alcohol/vegetable oil mixtures. Our data show that ultrasonic mixing produced smaller droplet sizes than conventional agitation, leading to more interfacial area for the reaction to occur. Droplet size distributions have been measured for conventional impeller and ultrasonic mixing systems using methanol/soybean oil as a model system. The dispersions were stabilized by surfactant in order to obtain droplet size distribution for mixture samples. Ultrasonic mixing produced dispersions with average droplet sizes 42% smaller than those generated using standard impellers.
Racial Differences in the Hurdling of Prenatal Care Barriers
Authors: Warner Geoffrey 
Published: August 2007

The success of black or white mothers in obtaining adequate prenatal care is examined. Two departures from public health convention are employed. The independent variables’ marginal effects are calculated from their logit coefficients. The odds ratio of care adequacy between races is derived from race-specific regressions. It yields a smaller variance and type II decision error likelihood compared to the race dummy method. A working-class life outlook and apathetic fathers are the highest barriers to adequate care. Wantedness, in the form of desired timing, is a very strong motivator. Improving upward socioeconomic mobility and paternal attitudes are important aspects of increasing prenatal care adequacy rates.