bluuebunny/crossref_metadata_2025 huggingface dataset:
Collagen/chitosan‐silicone membrane bilayer scaffold as a dermal equivalent
Authors: Shi Yanchao , Ma Lie , Zhou Jie , Mao Zhengwei , Gao Changyou
Published: January 2006

A bilayer dermal equivalent was fabricated by combining the collagen/chitosan porous scaffold with a silicone membrane. The macroscopic shapes and microstructures of the collagen/chitosan scaffolds with or without silicone membrane were illustrated. Water‐uptake was characterized by the phosphate buffered saline (PBS)‐immersion test. It was found that the glutaraldehyde treated scaffold had a higher water‐uptake ratio than that of the thermal treatment. The water vapor permeability of the bilayer dermal equivalent was tested under different humidities at room temperature. The results proved that the water vapor permeability of this bilayer dermal equivalent was close to normal adult skin. Investigation of the mechanical performance found that the bilayer dermal equivalent had a tensile stress of 0.1 MPa and a strain of 30% in the wet state. In vitro cell culture demonstrated that the bilayer dermal equivalent presented in this study did not show any cytotoxicity. Copyright © 2006 John Wiley & Sons, Ltd.
Characterization on polystyrene/zinc oxide nanocomposites prepared from solution mixing
Authors: Chae Dong Wook , Kim Byoung Chul
Published: January 2006

Polystyrene (PS)/zinc oxide (ZnO) nanocomposites were prepared by solution mixing, followed by film casting. The effects of ZnO nanoparticles on the physical properties of PS were investigated. Transmission electron microscopy (TEM) and field emission scanning electron microscopy (FESEM) showed that ZnO nanoparticles were homogeneously dispersed in the PS matrix. The introduction of 5 wt% ZnO increased slightly the glass transition temperature by 2.3°C. Thermal gravimetric analysis thermograms showed that the thermal stability of PS was enhanced with increasing ZnO content. Neither shift nor sharpening of absorption band was detected by infrared spectra. ZnO nanoparticles had little effect on the wide‐angle X‐ray diffraction (WAXD) pattern of PS. The transmittance of ultraviolet light was decreased with increasing ZnO content. PS/ZnO nanocomposites exhibited a small reduction in tensile strength and elongation to break. However, a significant enhancement in tensile modulus was achieved when 5 wt% ZnO was introduced. In the FESEM images of the tensile fractured surface, localized plastic deformation was observed for PS, while the site from which ZnO was pulled out was usually observed in the nanocomposites. Copyright © 2006 John Wiley & Sons, Ltd.
Preparation and characterization of optically active polymers containing pendent and terminal chiral units via atom transfer radical polymerization
Authors: Xu Wenjian , Zhu Xiulin , Zhu Jian , Cheng Zhenping
Published: January 2006

Optically active homopolymers and copolymers, bearing chiral units at the side chain and end chain, were prepared via atom transfer radical polymerization (ATRP) techniques. The well‐defined optically active polymers were obtained via the ATRP of pregnenolone methacrylate (PR‐MA), β‐cholestanol acrylate (CH‐A), and 20‐(hydroxymethyl)‐pregna‐1,4‐dien‐3‐one acrylate (HPD‐A) with ethyl 2‐bromopropionate as the initiator and CuBr/N,N,N′,N″,N″‐pentamethyldiethylenetriamine as the catalytic system. The experimental results showed that the polymerizations of PR‐MA, CH‐A, and HPD‐A proceeded in a living fashion, providing pendent chiral group polymers with low molecular weight distributions and predetermined molecular weights that increased linearly with the monomer conversion. Furthermore, the copolymers poly(pregnenolone methacrylate)‐b‐poly[(dimethylamino)ethyl methacrylate] and poly(pregnenolone methacrylate‐co‐methyl methacrylate) were synthesized and characterized with 1H NMR, transmission electron microscopy, and polarimetric analysis. In addition, when optically active initiators estrone 2‐bromopropionate and 20‐(hydroxymethyl)‐pregna‐1,4‐dien‐3‐one 2‐bromopropionate were used for ATRPs of methyl methacrylate and styrene, terminal optically active poly(methyl methacrylate) and polystyrene were obtained. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1502–1513, 2006
Organizational factors that influence safety
Authors: Killimett Patrick
Published: January 2006

For the past 20 years the author and his associates have worked with over 1600 organizations to improve safety performance. In the course of this work, we have discovered that organizations optimize their efforts when they provide and support strong roles at each of three levels: the front‐line employee, supervisory, and senior manager levels. These three roles, when appropriately engaged, make up a cord of three strands that is not easily broken.

Of these three areas, the leadership role has proved not only to have the greatest impact on safety improvement but also the most complex to understand and influence. One striking example of this is seen in the study of sites using the same improvement methodology. Even when compared by industry, site size, and systems, some organizations achieve steady improvement whereas others consistently struggle. More than any other factor, the quality of the organization's leadership—in particular its influence on the organizational culture—determined the level of success achieved. By organizational culture we mean the shared common values that drive organizational performance, more commonly defined as “the way we do things here.” Culture applies to many areas of functioning, is generally unstated, in the background, and slow to change.

Even though it is generally recognized that leadership is important to performance, the “how” of that leadership is often debated. What makes a leader effective at influencing and improving safety? What are the qualities of such a leader? What are the key tasks that a leader must perform to generate desired results?

Although this paper focuses on these questions with respect to senior leaders, the principles discussed are applicable to all levels in the organization. © 2006 Behavior Science Technology, Inc. (BST), 2006
A time‐saving approach for separating and focusing on human factors checklist discussion questions
Authors: Vaughen Bruce K.
Published: January 2006

The approach proposed in this report saves valuable process hazards analysis (PHA) team meeting time by quantifying and helping to separate a usually nonquantifiable subject: important process safety–related human factors issues. A human factors checklist modeled after the CCPS checklist is used and analyzed in three steps. First, operations, maintenance, engineering, and management personnel fill out responses to a 106‐question human factors checklist, using numbers ranging from 1 (“Okay As Is”) to 5 (“Needs Work”). Second, simple analysis on each question provided question‐related averages and standard deviations. Third, histograms on these results help to identify the ranges and to reduce the number of questions discussed by the team. The questions that showed general agreement had either high or low relative scores with low standard deviations; the questions that showed either diverse interpretations or opinions had high standard deviations. This approach saves the costs associated with longer PHA team meeting times because the discussion focuses on specific questions (issues) instead of all of the checklist questions. © 2006 American Institute of Chemical Engineers Process Saf Prog, 2006
Engineering supply chains as systems
Authors: Hassan Mohsen M. D.
Published: January 2006

In recent years companies in various fields form supply chains to support them manage their products and services during their life‐cycles. A supply chain usually extends from the source of raw material to end customers, consists of many components, and performs many functions. The components and functions have to be integrated in order to manage the flow of material, information, and finances from the source of raw material to end customers efficiently and at minimum cost. Further, a supply chain has a life‐cycle that is associated with the life‐cycle of the product(s) it supports, exists in an environment that impacts it, is dynamic, and has a purpose and objectives. With such aspects, a supply chain might better realize its potentials if it is viewed and treated as a system. This paper demonstrates the characteristics of systems inherent in supply chains and their implications on their design, and the ability of the systems engineering approach to the design of systems to benefit their formation. © 2006 Wiley Periodicals, Inc. Syst Eng 9: 73–89, 2006
A study of valley winds using the MIUU meso‐scale model
Authors: Bergström Hans , Juuso Nikolaus
Published: January 2006

High winds are sometimes found in low‐altitude terrain in mountain valleys. The reasons for this and the possibilities to find such sites from modelled wind fields are investigated. The higher‐order closure MIUU model developed at Uppsala University is used for a general study of channelling of winds in mountain valleys. The importance of length, width and depth of the valley is investigated. Comparisons are made with wind measurements. Copyright © 2006 John Wiley & Sons, Ltd.
Analytical modelling of wind speed deficit in large offshore wind farms
Authors: Frandsen Sten , Barthelmie Rebecca , Pryor Sara , Rathmann Ole , Larsen Søren , Højstrup Jørgen , Thøgersen Morten
Published: January 2006

The proposed model for the wind speed deficit in wind farms is analytical and encompasses both small wind farms and wind farms extending over large areas. As is often the need for offshore wind farms, the model handles a regular array geometry with straight rows of wind turbines and equidistant spacing between units in each row and equidistant spacing between rows. Firstly, the case with the flow direction being parallel to rows in a rectangular geometry is considered by defining three flow regimes. Secondly, when the flow is not in line with the main rows, solutions are suggested for the patterns of wind turbine units corresponding to each wind direction. The presentation is an outline of a model complex that will be adjusted and calibrated with measurements in the near future. Copyright © 2006 John Wiley & Sons, Ltd.
Cavum septum pellucidum and adhesio interthalamica in schizophrenia: an MRI study
Authors: Crippa José Alexandre de Souza , Zuardi Antonio Waldo , Busatto Geraldo F. , Sanches Rafael Faria , Santos Antonio Carlos , Araújo David , Amaro Edson , Hallak Jaime Eduardo Cecílio , Ng Virginia , McGuire Philip K.
Published: January 2006

Several studies have independently suggested that patients with schizophrenia are more likely to have an enlarged cavum septum pellucidum (CSP) and an absent adhesio interthalamica (AI), respectively. However, neither finding has been consistently replicated and it is unclear whether there is an association between these two midline brain abnormalities. Thus, we compared the prevalence of absent AI and the prevalence, size and volume of CSP in 38 patients with schizophrenia and 38 healthy controls using magnetic resonance imaging (MRI). There were no between group differences in the presence or volume of CSP; however, an enlarged CSP was commoner among patients than controls. There was also a positive correlation between CSP ratings and volumes. No differences in the presence or absence of the AI were found between patients and controls; however, an absent AI was commoner in male patients with schizophrenia than females. There was absolutely no overlap between the presence of a large CSP and an absence of AI. In conclusion, our findings are in line with several case series and other MRI investigations that have shown a higher incidence of putatively developmental brain abnormalities in patients with schizophrenia, particularly in males, and support the neurodevelopmental model of this disorder.
Brain‐specific angiogenesis inhibitor 2 regulates VEGF through GABP that acts as a transcriptional repressor
Authors: Jeong Byung Chul , Kim Mi-Young , Lee Ji Hee , Kee Hae Jin , Kho Dhong Hyo , Han Kae Eun , Qian Yong Ri , Kim Jong-Keun , Kim Kyung Keun
Published: January 2006

Previously, we reported that decreased brain‐specific angiogenesis inhibitor 2 (BAI2) induced increased VEGF expression. The regulatory mechanisms for this process are not understood. Here we show that GA‐binding protein gamma (GABPγ) associates with the cytoplasmic domain of BAI2, and GABPα/γ or GABPα/β works as a transcriptional repressor of VEGF in SHSY5Y cells. Transcriptional activity of wild‐type VEGF promoter was significantly increased in anti‐sense BAI2‐transfected cells, but not that of VEGF promoter harboring mutated GABP sites. In in vivo focal cerebral ischemia model, the decrease in BAI2 accompanied by decreased GABPα and GABPγ elicited increased VEGF expression before the onset of HIF‐1α. Our results point out that BAI2 controls VEGF transcription through GABP under normal conditions and cerebral ischemia.
Induction of apoptosis by p110C requires mitochondrial translocation of the proapoptotic BCL‐2 family member BAD
Authors: Chen Chen , Yan Jun , Sun Qing , Yao Luyang , Jian Yongzhi , Lu Jieqiong , Gu Jianxin
Published: January 2006

p110C, a 50‐kDa isoform of the PITSLRE kinase family, was demonstrated to play an important role in cell apoptosis. However, how p110C exactly promotes apoptosis is unclear. Our previous study showed that p110C interacted with p21‐activated kinase 1 (PAK1), an important kinase of the proapoptotic BCL‐2 family member BAD, and evidently inhibited its kinase activity. Here, we report that overexpression of p110C leads to decreased phosphorylation of BAD and its subsequent translocation from cytosol to mitochondria, which in turn induces the release of cytochrome c and the onset of apoptosis. Knocking down endogenous BAD expression will inhibit p110C induced apoptosis. Two kinase dead forms of p110C, D149N and K36N, lose the ability to inhibit the kinase activity of PAK1 and fail to induce the translocation of BAD and the BAD and such proapoptotic ability is associated with the kinase activity of p110C.
Fetal Growth Curves: Does Classification of Weight‐for‐Gestational Age Predict Risk of Hypoglycemia in the Term Newborn?
Authors: Johnson Teresa S. , Hillery Julie M. , Engstrom Janet L.
Published: January 2006

Our objective was to determine whether classification of birth weight as small, average, or large for gestational age using published fetal growth curves is predictive of a term infant's risk of hypoglycemia. This prospective, descriptive study measured and plotted birth weight measurements on six published fetal growth curves to classify infant birth weight as small, average, or large for gestational age. Glucose levels were measured 2 hours after birth to determine the prevalence of hypoglycemia. The sensitivity, specificity, and positive/negative predictive values were calculated for each fetal growth curve, and odds ratios were calculated. The patients were 157 clinically stable term Caucasian and African American infants of nondiabetic mothers from a community hospital in midwestern United States. Ten of the 20 (50%) infants with hypoglycemia were classified as average for gestational age on all six published fetal growth curves. Calculated odds ratios demonstrated that none of the six published fetal growth curves significantly predicted the risk of hypoglycemia based on classification of birth weight as small, average, or large for gestational age. The risk of hypoglycemia in term infants was not accurately predicted by classification of birth weight as small, average, or large for gestational age. Clinicians should use other methods to predict which term infants are at risk for hypoglycemia.
Environmental Health Information Resources: Healthy Environments for Healthy Women and Children
Authors: Arnesen Stacey J.
Published: January 2006

Because of concerns about exposure (e.g., from pesticides in the garden to how much fish is safe to eat), health professionals are often asked to address the effect of environmental agents on women's health. Numerous environmental health resources are available on the Internet, but with so many Web sites, it can be difficult to identify high‐quality, accurate information oriented toward a wide variety of needs and users. This article describes environmental health and toxicology databases and resources from the National Library of Medicine (NLM) and other government agencies and organizations, that contain valuable information on potential environmental risks to women.
Natural Eating Behavior in Latent Labor and Its Effect on Outcomes in Active Labor
Authors: Parsons Myra , Bidewell John , Nagy Sue
Published: January 2006

This study examined the effect of eating during the latent phase of labor on the hospital‐estimated labor duration and birth outcomes for the mother and baby. A prospective, comparative trial with concurrent controls compared labor duration and outcomes of 176 low‐risk, nulliparous women who birthed at four hospitals in Sydney, Australia. Food was voluntarily consumed by 82 women, whereas 94 consumed clear fluids only. Food intake during the latent phase of the first stage of labor was associated with a longer duration of labor (mean difference = 2.35 hours). No difference was found between eating and noneating groups for the rate of medical interventions, adverse birth outcomes, or vomiting. Results suggest that eating during the latent phase of labor may increase labor duration.
The route to self-similarity in turbulent jets and plumes
Authors: CARAZZO GUILLAUME , KAMINSKI EDOUARD , TAIT STEPHEN
Published: January 2006

The description of entrainment in turbulent free jets is at the heart of physical models of some major flows in environmental science, from volcanic plumes to the dispersal of pollutant wastes. The classical approach relies on the assumption of complete self-similarity in the flows, which allows a simple parameterization of the dynamical variables in terms of constant scaling factors, but this hypothesis remains under debate. We use in this paper an original parameterization of entrainment and an extensive review of published experimental data to interpret the discrepancy between laboratory results in terms of the systematic evolution of the dynamic similarity of the flow as a function of downstream distance from the source. We show that both jets and plumes show a variety of local states of partial self-similarity in accordance with the theoretical analysis of George (1989), but that their global evolution tends to complete self-similarity via a universal route. Plumes reach this asymptotic regime faster than jets which suggests that buoyancy plays a role in more efficiently exciting large-scale modes of turbulence.
The value of a long-term bushmeat market dataset as an indicator of system dynamics
Authors: CROOKES D.J. , ANKUDEY N. , MILNER-GULLAND E.J.
Published: January 2006

Data on prices and quantities of wildlife on sale in markets are increasingly being used as indicators of the sustainability of bushmeat hunting, being relatively easy to collect. However, it is not clear how much can actually be inferred from trends in such data. This study analyses changes in price, quantity, method of capture and kill location of bushmeat species entering the Atwemonom bushmeat market in the city of Kumasi (Ghana) over the period 1987–2002, using data collected by an official of the Ghana Wildlife Department. The analysis was confined to the seven most commonly traded species and to the open season only, in order to maximize the reliability of the data. Over the period, there was an increase in real bushmeat prices, in the proportion of animals killed by means other than guns and the trade made up by grasscutters (Thryonomys swinderianus). A higher proportion of animals originated from distant areas, rather than from villages close to Kumasi. These trends are compatible both with depletion of the bushmeat resource and with an economically rational response by hunters to increasing prices. The analysis highlights both the utility and the limitations of detailed long-term market data as a tool for assessing the sustainability of wildlife hunting. Data on the origin of animals sold in the market and the gear type are necessary but not sufficient for understanding the drivers of changes in price and quantity of species on sale in markets; without complementary detailed local data on hunter behaviour, market data are of little value.
Cryptococcose disseminée: Manifestation inaugurale d'un sida
Authors: Fournier  , Bellini  , Baur  , Waeber  , Cavassini
Published: January 2006

La cryptococcose disséminée est une maladie caractéristique des patients affectés par le SIDA. Nous analysons l'évolution d'une patiente souffrant d'une cryptococcose disséminée compliquée par un échappement lors de la dixième semaine d'un traitement d'induction d'amphotéricine B. Ce cas illustre l'importance du bilan infectieux initial, du suivi clinique et thérapeutique de ces patients à haut risque de développer de nombreuses maladies opportunistes et complications médicamenteuses.
Patientin mit der Überzeugung, an einer Stoffwechselstörung zu leiden
Authors: Hänsel
Published: January 2006

Dieser Fall schildert eine Patientin mit einer somatoformen Störung und bietet Hilfsmittel für Praktiker eine psychiatrische Komorbidität bei PatientInnen in der allgemeinen Sprechstunde zu erkennen.
Predicting Spontaneous Big Five Behavior with Implicit Association Tests
Authors: Steffens Melanie C. , Schulze König Stefanie
Published: January 2006

According to theories brought forward recently, implicit measures based on reaction times, for instance Implicit Association Tests (IATs), should predict spontaneous behavior better than explicit measures. We applied five IATs to the measurement of the Big Five personality factors and tested whether the IATs predicted spontaneous behavior. The results show that, although implicit and explicit measures of personality dimensions were related at times, the correlations between them and with behavior suggest that these constructs should be differentiated. IATs predicted spontaneous behavior, but explicit measures did not. In contrast, explicit measures, but not IATs, were related to transparent self-ratings of behavior.
Assessment of the Validity of Parenting Constructs Using the Multitrait-Multimethod Model
Authors: Villar Paula , Luengo M. Angeles , Gómez-Fraguela José A. , Romero Estrella
Published: January 2006

The validity and convergence between adolescents', mothers' and fathers' reports of five parenting constructs (family conflict, family communication, permissive parenting, authoritative parenting, and authoritarian parenting) were examined. Questionnaire data were collected from 302 families with children in the first and second year of secondary education and confirmatory factor analysis (CFA) was used to test three multitrait-multimethod (MTMM) models containing five parenting constructs as trait factors and adolescents', mothers', and fathers' reports as method factors. The CFA approach to MTMM data revealed a multidimensional structure in which both measurement method and parenting traits accounted for covariation among data. The CFA results also demonstrated that the family members' perspectives converged in the measure of family conflict and family communication constructs. Results also indicated method effects for the other three constructs reflecting parenting styles. Implications of these findings are discussed.
Scaling of fracture energies: The rationalization of different laboratory measurements
Authors: Xia Kaiwen
Published: January 2006

The fracture energy GC is an important parameter involved in earthquake processes. Researchers have been trying to estimate GC from both geophysical field data and laboratory fracture experiments conducted on either intact rocks or frictional contacts (faults) simulated by saw‐cut rocks. The GC measured from these two types of experiments can differ by several orders of magnitude, and the reason for this difference is still unknown. I show that if we divide GC into three parts, namely surface energy, frictional fracture energy, and the damage zone energy, we can explain this discrepancy through simple scaling relations. I also attempt to make the connection from the laboratory measured GC to the seismological estimates.
Evidence for fluid migration as the source of deformation at Campi Flegrei caldera (Italy)
Authors: Battaglia Maurizio , Troise Claudia , Obrizzo Francesco , Pingue Folco , De Natale Giuseppe
Published: January 2006

We model the location, geometry and density of the source of the recent geological unrest at Campi Flegrei caldera (Italy) by inverting levelling, trilateration and gravity measurements collected between 1980 and 1995. The best fitting source for the 1980–84 inflation is a horizontal penny‐shaped crack with a density 142 to 1115 kg/m3. The source best fitting the deflation period (1990–95) is a vertical spheroid with density between 902 and 1015 kg/m3. These results exclude the intrusion of magma, and indicate the migration of fluid to and from the caldera hydrothermal system as the cause of ground deformation and consequent unrest.
Spirit rover localization and topographic mapping at the landing site of Gusev crater, Mars
Authors: Li Rongxing , Archinal Brent A. , Arvidson Raymond E. , Bell Jim , Christensen Philip , Crumpler Larry , Des Marais David J. , Di Kaichang , Duxbury Tom , Golombek Matt , Grant John , Greeley Ronald , Guinn Joe , Johnson Andrew , Kirk Randolph L. , Maimone Mark , Matthies Larry H. , Malin Mike , Parker Tim , Sims Mike , Thompson Shane , Squyres Steven W. , Soderblom Larry A.
Published: January 2006

By sol 440, the Spirit rover has traversed a distance of 3.76 km (actual distance traveled instead of odometry). Localization of the lander and the rover along the traverse has been successfully performed at the Gusev crater landing site. We localized the lander in the Gusev crater using two‐way Doppler radio positioning and cartographic triangulations through landmarks visible in both orbital and ground images. Additional high‐resolution orbital images were used to verify the determined lander position. Visual odometry and bundle adjustment technologies were applied to compensate for wheel slippage, azimuthal angle drift, and other navigation errors (which were as large as 10.5% in the Husband Hill area). We generated topographic products, including 72 ortho maps and three‐dimensional (3‐D) digital terrain models, 11 horizontal and vertical traverse profiles, and one 3‐D crater model (up to sol 440). Also discussed in this paper are uses of the data for science operations planning, geological traverse surveys, surveys of wind‐related features, and other science applications.
Neuronal–Glial Glucose Oxidation and Glutamatergic–GABAergic Function
Authors: Hyder Fahmeed , Patel Anant B , Gjedde Albert , Rothman Douglas L , Behar Kevin L , Shulman Robert G
Published: January 2006

Prior 13C magnetic resonance spectroscopy (MRS) experiments, which simultaneously measured in vivo rates of total glutamate-glutamine cycling (Vcyc(tot)) and neuronal glucose oxidation ( CMRglc(ox), N), revealed a linear relationship between these fluxes above isoelectricity, with a slope of ~1. In vitro glial culture studies examining glutamate uptake indicated that glutamate, which is cotransported with Na+, stimulated glial uptake of glucose and release of lactate. These in vivo and in vitro results were consolidated into a model: recycling of one molecule of neurotransmitter between glia and neurons was associated with oxidation of one glucose molecule in neurons; however, the glucose was taken up only by glia and all the lactate (pyruvate) generated by glial glycolysis was transferred to neurons for oxidation. The model was consistent with the 1:1 relationship between Δ CMRglc(ox), N and Δ Vcyc(tot) measured by 13C MRS. However, the model could not specify the energetics of glia and γ-amino butyric acid (GABA) neurons because quantitative values for these pathways were not available. Here, we review recent 13C and 14C tracer studies that enable us to include these fluxes in a more comprehensive model. The revised model shows that glia produce at least 8% of total oxidative ATP and GABAergic neurons generate ~18% of total oxidative ATP in neurons. Neurons produce at least 88% of total oxidative ATP, and take up ~26% of the total glucose oxidized. Glial lactate (pyruvate) still makes the major contribution to neuronal oxidation, but ~30% less than predicted by the prior model. The relationship observed between Δ CMRglc(ox), N and Δ Vcyc(tot) is determined by glial glycolytic ATP as before. Quantitative aspects of the model, which can be tested by experimentation, are discussed.
CBF Changes Associated with Focal Ischemic Preconditioning in the Spontaneously Hypertensive Rat
Authors: Zhao Liang , Nowak Thaddeus S
Published: January 2006

Experimental stroke models exhibit robust protection after prior preconditioning (PC) insults. This study comprehensively examined cerebral blood flow (CBF) responses to permanent middle cerebral artery (MCA) occlusion in spontaneously hypertensive rats preconditioned by noninjurious transient focal ischemia, using [14C]iodoantipyrine autoradiography at varied occlusion intervals. Preconditioning was produced by 10-min occlusion of the MCA and ipsilateral common carotid artery under halothane anesthesia. These vessels were permanently coagulated 24 h later in naïve, PC, and sham-operated rats. Infarct volumes were determined from hematoxylin-eosin-stained frozen sections after 1 or 3 days. Edema-corrected infarct volume was reduced from 127±21 in naïve rats to 101 ±31 and 52±28 mm3 in sham and PC groups, respectively, at 1 day, with similar results at 3 days. All animals exhibited a consistent CBF threshold for infarction (approximately 30mL/100g/ min). Tissue volumes below this threshold were identical in naïve and PC groups after 15-min occlusion. However, by 3 h the volume of ischemic cortex decreased in the PC group but remained unchanged in naïve rats, predicting final infarct volumes. Cerebral blood flow recovery was confirmed in brains of individual rats evaluated by repeated laser Doppler perfusion imaging during the same 3-h interval. Modest sham protection correlated with better-maintained global perfusion, detectable also in the contralateral cortex, apparently reflecting the PC effects of prior anesthesia. These results establish that timely reperfusion of penumbra, achieved by synergistic mechanisms, is a primary determinant of PC-induced protection in experimental stroke.
Closure of fluid equations in collisionless magnetoplasmas
Authors: Chust T. , Belmont G.
Published: January 2006

The possibility of using fluid equations in collisionless plasmas is revisited, and the conditions of validity of several possible closure equations are investigated. A new derivation of the well-known “double-adiabatic” Chew-Goldberger-Low (CGL) laws is first presented. These laws are shown to demand two different kinds of conditions for ensuring (1) particle gyrotropy and (2) adiabaticity. Both kinds of conditions are investigated in detail. The usual slow and large-scales conditions (hereafter “sls”), which are shown to be necessary for gyrotropy, are provided in a rigorous form. The role of the fundamental symmetries of the system, especially in the directions parallel and perpendicular to the magnetic field, is also emphasized for determining any “fluid-type” behavior of a collisionless magnetoplasma. More general closure equations are afterwards proposed, relaxing first the conditions for adiabaticity and then, more speculatively, the sls conditions for gyrotropy. The dependence of these new closure equations on the shape of the velocity distribution functions is discussed, the CGL case being singular since it is shown to be fully independent of this shape.
The properties of ion-water clusters. II. Solvation structures of Na+, Cl−, and H+ clusters as a function of temperature
Authors: Burnham Christian J. , Petersen Matt K. , Day Tyler J. F. , Iyengar Srinivasan S. , Voth Gregory A.
Published: January 2006

Ion-water-cluster properties are investigated both through the multistate empirical valence bond potential and a polarizable model. Equilibrium properties of the ion-water clusters H+(H2O)100, Na+(H2O)100, Na+(H2O)20, and Cl−(H2O)17 in the temperature region 100–450 K are explored using a hybrid parallel basin-hopping and tempering algorithm. The effect of the solid-liquid phase transition in both caloric curves and structural distribution functions is investigated. It is found that sodium and chloride ions largely reside on the surface of water clusters below the cluster melting temperature but are solvated into the interior of the cluster above the melting temperature, while the solvated proton was found to have significant propensity to reside on or near the surface in both the liquid- and solid-state clusters.
Kramers escape rate in nonlinear diffusive media
Authors: JiangLin Zhao , Bao Jing-Dong , Wenping Gong
Published: January 2006

In this paper, we study nonlinear Kramers problem by investigating overdamped systems ruled by the one-dimensional nonlinear Fokker-Planck equation. We obtain an analytic expression for the Kramers escape rate under quasistationary conditions by employing a metastable potential and its predictions are in excellent agreement with numerical simulations. The results exhibit the anomalies due to the nonlinearity in W that the escape rate grows with D and drops as μ becomes large at a fixed D. Indeed, particles in the subdiffusive media (μ>1) can escape over the barrier only when D is above a critical value, while this confinement does not exist in the superdiffusive media (μ<1).
Stabilizing long-period orbits via symbolic dynamics in simple limiter controllers
Authors: Zhou C. T.
Published: January 2006

We present an efficient approach to determine the control parameter of simple limiter controllers by using symbolic dynamics of one-dimensional unimodal maps. By applying addition- and subtraction-symbol rules for generating an admissible periodic sequence, we deal with the smallest base problem of the digital tent map. The proposed solution is useful for minimizing the configuration of digital circuit designs for a given target sequence. With the use of the limiter controller, we show that one-dimensional unimodal maps may be robustly employed to generate the maximum-length shift-register sequences. For an arbitrary long Sarkovskii sequence, the control parameters are analytically given.
Au and Pd atoms adsorbed on pure and Ti-doped SiO2∕Mo(112) films
Authors: Giordano Livia , Del Vitto Annalisa , Pacchioni Gianfranco
Published: January 2006

The interaction of Pd and Au atoms with a silica surface and SiO2∕Mo(112) ultrathin films has been studied with periodic density-functional theory-generalized gradient approximation calculations. On both unsupported and supported silica, Pd and Au are weakly bound. No charge transfer occurs to the empty Pd and Au orbitals. Differently from Au, Pd can easily penetrate with virtually no barrier into the hexagonal rings of the supported silica film and binds strongly at the SiO2–Mo interface. The same process for Au implies overcoming a barrier of 0.9 eV. Completely different is the behavior of Ti-doped silica films. Au forms a direct covalent bond with substitutional Ti at the expense of the Ti⋯O–Mo interface bond which breaks. The global process is exothermic by 1 eV and nonactivated, showing that Ti doping results in solid anchoring points for the adsorbed Au atoms and for nucleation and growth of small gold particles. The effect of Ti doping is less pronounced for Pd but still visible with substantial enhancement of the Pd adsorption strength.
Design of a timing circuit for random laser triggering on aerosol particles
Authors: Mysak Erin R. , Dessiaterik Yury N. , McKinney C. J. , Miller Roger E. , Baer Tomas
Published: January 2006

A versatile timing device has been developed that permits a variety of lasers, including Nd:YAG (yttrium aluminum garnet), excimer, and CO2 lasers, to be triggered at random times. The present application is to single-particle mass spectrometry, where the corresponding arrival times are random and signaled by a laser light-scattering apparatus. The timing circuit triggers the Nd:YAG laser flashlamps approximately 200μs prior to the desired laser output pulse, followed by the Q-switch triggering pulses, which can also be used to control other lasers and/or the ion extraction optics. The flashlamps are discharged ten times per second to maintain the proper heat load on the Nd:YAG laser flashlamps. If fewer than 10particles∕s are detected by light-scattering apparatus, the unit sends substitute pulses to maintain the average of 10discharges∕s. When the particle flux is higher than ten per second, the circuit is designed to ignore the extra particle events. A simpler version of the circuit is also described, which accepts two timing inputs and outputs a pulse for ion extraction at a preselected time.
Study of non-Maxwellian trapped electrons by using generalized (r,q) distribution function and their effects on the dynamics of ion acoustic solitary wave
Authors: Mushtaq A. , Shah H. A.
Published: January 2006

By using the generalized (r,q) distribution function, the effect of particle trapping on the linear and nonlinear evolution of an ion-acoustic wave in an electron-ion plasma has been discussed. The spectral indices q and r contribute to the high-energy tails and flatness on top of the distribution function respectively. The generalized Korteweg–de Vries equations with associated solitary wave solutions for different ranges of parameter r are derived by employing a reductive perturbation technique. It is shown that spectral indices r and q affect the trapping of electrons and subsequently the dynamics of the ion acoustic solitary wave significantly.
The precursors of the solvated electron in methanol studied by femtosecond pump-repump-probe spectroscopy
Authors: Thaller A. , Laenen R. , Laubereau A.
Published: January 2006

Using UV photoionization and delayed near-infrared reexcitation pulses, a novel time-, frequency-, and polarization-resolved pump-repump-probe spectroscopy is conducted in the probing range of 450–2400 nm with improved experimental accuracy. Both the generation process and relaxation dynamics following selective repumping of intermediate species of the solvated electron are investigated and analyzed self-consistently with the help of a kinetic model. New insight in the intermediates of the trapped electron is gained leading to a unique microscopic picture.
Colliding wave solutions from five-dimensional black holes and black p-branes
Authors: Halilsoy E. , Halilsoy M. , Unver O.
Published: January 2006

We consider both the five-dimensional Myers-Perry and Reissner-Nordstrom black holes (BHs) and black p-branes in (4+p)-dimensions. By employing the isometry with the colliding plane waves (CPWs) we generate Cauchy-Horizon (CH) forming CPW solutions. From the five-dimensional vacuum solution through the Kaluza-Klein reduction the corresponding Einstein-Maxwell-dilaton solution is obtained. This CH forming cross polarized solution with the dilaton turns out to be a rather complicated nontype D metric. Since we restrict ourselves to the five-dimensional BHs we obtain exact solutions for colliding 2- and 3-form fields in (p+4)-dimensions for p⩾1. By dualizing these forms we can obtain also colliding (p+1)- and (p+2)-forms which are important processes in the low energy limit of the string theory. All solutions obtained are CH forming, implying that an analytic extension beyond is possible.
A bound on the mutual information, and properties of entropy reduction, for quantum channels with inefficient measurements
Authors: Jacobs Kurt
Published: January 2006

The Holevo bound is a bound on the mutual information for a given quantum encoding. In 1996 Schumacher, Westmoreland, and Wootters [Phys. Rev. Lett. 76, 3452 (1996)] derived a bound that reduces to the Holevo bound for complete measurements, but that is tighter for incomplete measurements. The most general quantum operations may be both incomplete and inefficient. Here we show that the bound derived by SWW can be further extended to obtain one that is yet again tighter for inefficient measurements. This allows us, in addition, to obtain a generalization of a bound derived by Hall, and to show that the average reduction in the von Neumann entropy during a quantum operation is concave in the initial state, for all quantum operations. This is a quantum version of the concavity of the mutual information. We also show that both this average entropy reduction and the mutual information for pure state ensembles, are Schur concave for unitarily covariant measurements; that is, for these measurements, information gain increases with initial uncertainty.
Flux-surface shaping effects on tokamak edge turbulence and flows
Authors: Kendl Alexander , Scott Bruce D.
Published: January 2006

Shaping of magnetic flux surfaces is found to have a strong impact on turbulence and transport in tokamak edge plasmas. A series of axisymmetric equilibria, with varying elongation and triangularity, and a divertor configuration are implemented into a computational gyrofluid turbulence model. The mechanisms of shaping effects on turbulence and flows are identified. Transport is mainly reduced by local magnetic shearing and an enhancement of zonal shear flows induced by elongation and X-point shaping.
Geometrical and electronic properties of neutral and charged cesium clusters Csn(n=2–10): A theoretical study
Authors: Ali (Basu) M. , Maity D. K. , Das D. , Mukherjee T.
Published: January 2006

We have investigated the structure and electronic properties of cesium clusters following all electron ab initio theoretical methods based on configuration interaction, second-order Moller-Plesset (MP2) perturbation theory, and density-functional theory. Becke’s three-parameter nonlocal hybrid exchange-correlation functional (B3LYP) is found to perform best on the present systems with a split valence 3-21G basis function. We have calculated the optimized geometries of neutral and singly charged cesium clusters having up to ten atoms, their binding energy per atom, ionization potentials (IPs), and adiabatic electron affinity (EA). Geometry optimizations for all the clusters are carried out without imposing any symmetry restriction. The neutral clusters having up to six atoms prefer planar structure and three-dimensional structure is preferred only when the number of atoms in a cluster is more than six. There is a good agreement between the present theoretical and reported experimental IP values for the neutral clusters with cluster size n⩽10. Calculated EA is also in good agreement with the available experimental data for the small Cs clusters. Similar calculations have also been carried out for small Rb clusters and the performance of B3LYP is equally good. Thermodynamic properties such as enthalpy and entropy for small Cs and Rb clusters have also been calculated and are well compared with the experimental data.
Chaos in computer performance
Authors: Berry Hugues , Gracia Pérez Daniel , Temam Olivier
Published: January 2006

Modern computer microprocessors are composed of hundreds of millions of transistors that interact through intricate protocols. Their performance during program execution may be highly variable and present aperiodic oscillations. In this paper, we apply current nonlinear time series analysis techniques to the performances of modern microprocessors during the execution of prototypical programs. Our results present pieces of evidence strongly supporting that the high variability of the performance dynamics during the execution of several programs display low-dimensional deterministic chaos, with sensitivity to initial conditions comparable to textbook models. Taken together, these results show that the instantaneous performances of modern microprocessors constitute a complex (or at least complicated) system and would benefit from analysis with modern tools of nonlinear and complexity science.
The effects of the prepulse on capillary discharge extreme ultraviolet laser
Authors: Shuker M. , Ben-kish A. , Nemirovsky R. A. , Fisher A. , Ron A.
Published: January 2006

In the past few years collisionally pumped extreme ultraviolet (XUV) lasers utilizing a capillary discharge were demonstrated. An intense current pulse is applied to a gas-filled capillary, inducing magnetic collapse (Z pinch) and formation of a highly ionized plasma column. Usually, a small current pulse (prepulse) is applied to the gas in order to preionize it prior to the onset of the main current pulse. In this paper we investigate the effects of the prepulse on a capillary discharge Ne-like Ar XUV laser (46.9nm). The importance of the prepulse in achieving suitable initial conditions of the gas column and preventing instabilities during the collapse is demonstrated. Furthermore, measurements of the amplified spontaneous emission (ASE) properties (intensity and duration) in different prepulse currents revealed unexpected sensitivity. Increasing the prepulse current by a factor of 2 caused the ASE intensity to decrease by an order of magnitude and to nearly disappear. This effect is accompanied by a slight increase in the lasing duration. We attribute this effect to axial flow in the gas during the prepulse.
Dielectric tensor for a plasma with a loss-cone kappa-Maxwellian velocity distribution
Authors: Singhal R. P. , Tripathi A. K.
Published: January 2006

Components of the dielectric tensor are obtained for a kappa-Maxwellian velocity distribution with loss-cone feature for a hot, infinite, homogeneous plasma immersed in a uniform magnetic field. Expansions valid for small propagation angle (angle between the wave vector and the ambient magnetic field) are given for the elements of the dielectric tensor.
Link between fluid and kinetic parameters near the plasma boundary
Authors: Kuhn S. , Riemann K.-U. , Jelić N. , Tskhakaya D. D. , Tskhakaya D. , Stanojević M.
Published: January 2006

In this paper the general problem of linking fluid and kinetic plasma parameters, with special attention devoted to the plasma boundaries where, due to strong deviations from thermodynamic equilibrium, there are intrinsic difficulties regarding the closure of the hydrodynamic equations, is considered. This problem is demonstrated by means of two examples for which the solutions of the kinetic equations are known. These examples are the collision-free Tonks-Langmuir model [Phys. Rev. 34, 876 (1929)] and Riemann’s presheath model [Phys. Fluids 24, 2163 (1981)] dominated by charge-exchange collisions. It is found that in the vicinity of the sheath edge the “polytropic” coefficient γ(x) shows an unexpected behavior that contradicts the commonly used hydrodynamic approaches assuming γ=const. In spite of all differences, the two models investigated exhibit quite similar behavior of the hydrodynamic quantities and of the polytropic coefficient in the presheath and sheath regions. This rises to hopes that the results presented in this paper can be generalized to models characterizing other physical scenarios of plasma production and confinement. In particular, the basic findings presented here will, in suitably adopted form, be of importance, e.g., in properly formulating boundary conditions for fluid codes simulating bounded plasmas.