bluuebunny/crossref_metadata_2025 huggingface dataset:
Rural Hospital Preparedness for Neonatal Resuscitation
Authors: Jukkala Angela , Henly Susan J. , Lindeke Linda
Published: September 2008

ABSTRACT: 
Context: Neonatal resuscitation is a critical component of perinatal services in all settings. Purpose: To systematically describe preparedness of rural hospitals for neonatal resuscitation, and to determine whether delivery volume and level of perinatal care were associated with overall preparedness or its indicators. Methods: We developed the 15‐point Hospital Neonatal Resuscitation Survey to examine institutional preparedness for neonatal resuscitation in 4 areas: policy and procedure, resuscitation team membership, continuing education, and connections with a wider system of perinatal care. All 58 rural hospitals with perinatal services in 2 upper Midwestern states (North Dakota and Minnesota) were asked to provide information describing preparedness for neonatal resuscitation. Nursing administrators responded to the survey. Findings: A total of 26 hospitals took part. Annual delivery volume ranged from 4 to 958. Preparedness scores ranged from 4 to 12. Hospitals with more than 125 deliveries each year reported significantly higher levels of preparedness than lower volume hospitals (9.50 vs 5.83, P < .001). Overall preparedness was not associated with level of perinatal care. Most rural hospitals did not identify a formal collaborative relationship with a regional level III perinatal center. Conclusions: Substantial variation in hospital preparedness for neonatal resuscitation was identified. Preparedness was associated with delivery volume. Lack of collaborative agreements between rural hospitals and level III perinatal centers was pervasive. Additional research into the measurement of hospital preparedness for neonatal resuscitation as a component of quality rural perinatal care is needed to optimize outcomes for rural‐born neonates.
The role of caveolin‐1 in cardiovascular regulation
Authors: Rahman A. , Swärd K.
Published: September 2008

Caveolae are omega‐shaped membrane invaginations present in essentially all cell types in the cardiovascular system, and numerous functions have been ascribed to these structures. Caveolae formation depends on caveolins, cholesterol and polymerase I and transcript release factor‐Cavin (PTRF‐Cavin). The current review summarizes and critically discusses the cardiovascular phenotypes reported in caveolin‐1‐deficient mice. Major changes in the structure and function of heart, lung and blood vessels have been documented, suggesting that caveolae play a critical role at the interface between blood and surrounding tissue. According to an emerging paradigm, many of these changes are secondary to uncoupling of endothelial nitric oxide synthase. Thus, nitric oxide synthase not only synthesizes more nitric oxide in the absence of caveolin‐1, but also more superoxide with potential pathogenic consequences. It is further argued that the vasodilating drive from increased nitric oxide production in caveolin‐1‐deficient mice is balanced by changes in the vascular media that favour increased dynamic resistance regulation. Harnessing the therapeutic opportunities buried in caveolae, while challenging, could expand the arsenal of treatment options in cancer, lung disease and atherosclerosis.
Calcific annuli in the aorta of a dog
Authors: DEAR M. G.
Published: September 2008

This report describes a case with calcific annuli in the aorta, together with severe mitral insufficiency of the heart as well as myocarditis and bronchitis. Physical, radiographic, electrocardiographic, biochemical and haematological features are reported. The incidence of calcification of the cardiovascular system, the site and nature of the calcific lesion and haeniodynamic correlates with the combination of coarctation of the aorta and mitral insufficiency in man are discussed.

Résumé. On rapporte un cas de calcifications annulaires de l'aorte, accompagnées d'insuffisance mitrale, de myocardite et de bronchite; on décrit les constatations d'ordre physique, radiologique, électrocardiographique, biochimique et hématologique. On discute la fréquence des calcifications du système cardiovasculaire, leur siège, leur nature, leurs implications hémodynamiques et les rapports qui existent entre elles et l'association du rétrécissement aortique et l'insuffisance mitrale dans l'espèce humaine.

Zusammenfassung. Dieser Bericht beschreibt einen Fall von calcifizierten Annuli in der Aorta in Verbindung mit schwerer Mitralinsuffizienz des Herzens, Myocarditis und Bronchitis. Körperliche, röntgenologische, elektrokardiographische, biochemische und hämatologische Befunde werden angegeben. Korrelationen der Häufigkeit der Calcifizierung des cardiovasculären Systems, des Ortes und des Charakters dieser Läsion und der Blutdruckverhältnisse mit der Kombination von Aortenisthmusstenose und Mitralinsuffizienz beim Menschen werden besprochen.
Clinical and pathological aspects of cervical disc protrusion and primary tumours of the cervical spinal cord in the dog*
Authors: PALMER A. C.
Published: September 2008

A short account is given of the pathological changes that occur in the spinal cord of the dog as a result of prolapsed intervertebral discs and this includes a description of pressure‐induced injury to local nerve roots. The clinical features are also described of five dogs suffering from primary tumours of the cervical spinal cord and an attempt is made to differentiate this condition clinically from cervical disc protrusion.

Résumé. On rapporte brièvenicnt les modifications anatomo‐pathologiques obscrvées au nivcau de la moelle du chien à la suite du prolapsus du disclue intervertébral et on dérit les lésions des racines nerveuses intéressées, produites par la pression. Les aspects cliniques sont égalemcnt décrits; il s'agissait de cinq chiens attcints de tumeur primaire de la moelle cervicale ct on présente un essai de différenciation des signes permettant de faire le diagnostic différentiel entre cet état et la protrusion d'un disque cervical.

Zusammenfassung. Es wird cin kurzer Bericht über die pathologischen Verändrrungen gegeben, die im Rückcnmark des Hundes als Folge eines Zwischenwirbelscheibenvorfalls eintreten, was eine Beschreibung der durch Druck verursachten Schädigungen örtlicher Nervenwurzeln einschliesst. Es werden auch die klinische Befunde hei fünf Hunden beschrieben, die an primären Tumoren des Cervicalmarks leiden, und es wird versucht, diescn Zustand klinisch von der Protrusio cervicaler Zwischenwirbelscheiben zu differenzieren.
Grain, pellet and wax block bait take by the house mouse (Mus musculus) and non‐target species: implications for mouse eradications on coral cay islands
Authors: CRUZ Jennyffer , LEUNG Luke K.‐P. , LISLE Allan , RIVERA Dario F. , STAPLES Linton , SMITH Michelle
Published: September 2008

Introduced rodents have been eradicated from large numbers of offshore islands using toxic baits; however, toxic baits have been linked with negative impacts on non‐target species. The present study assessed the bait take of target (house mouse, Mus musculus) and non‐target (buff banded rail, Rallus philippensis) animals on Northwest and Heron Islands in the Great Barrier Reef. Three non‐toxic bait formulations (wax block, pellet and grain) were tested and each was applied at 1 kg ha−1 in six treatment grids. The tracks of animals visiting the baits were identified using 30 tracking stations per treatment grid. A tracking station consisted of a track‐board placed in the centre of a sand‐pad. Mean bait take differed significantly between the formulations: birds took more grain bait than wax block bait; mice took more wax block than grain bait. Both mice and birds were equally selective of pellet bait. Thus, the findings indicate that wax blocks are the most suitable formulation for future baiting programs to eradicate mice on these and other islands.
Combined effects of gallic acid and propolis on beryllium‐induced hepatorenal toxicity
Authors: NIRALA Satendra K. , LI Peiqiang , BHADAURIA Monika , GUO Guangqin
Published: September 2008

The combined effect of gallic acid (3,4,5‐trihydroxy benzoic acid; GA; 50 mg kg−1i.p.) and propolis (200 mg kg−1p.o.) was evaluated against beryllium‐induced biochemical and morphological alterations in the liver and kidney. Female albino rats were exposed to beryllium nitrate (1 mg kg−1i.p.) daily for 28 days followed by treatment with the above mentioned therapeutic agents either individually or in combination for five consecutive days. Exposure to beryllium increased its concentration in the serum, liver and kidney and caused significant alterations in cytochrome P450 enzymes, microsomal lipid peroxidation and protein contents. Beryllium administration significantly altered the aspartate aminotransaminase, alanine aminotransaminase, lactate dehydrogenase, γ‐grutamy1 transpeptidase, bilirubin, creatinine and urea in serum, and the activity of acid phosphatase, alkaline phosphatase, adenosine triphosphatase, glucose‐6‐phophatase and succinic dehydrogenase, triglycerides, cholesterol, protein contents, glycogen contents, lipid peroxidation and glutathione level in the liver and kidney. Beryllium exposure induced severe alterations in hepatorenal morphology, revealing its toxic consequences at a cellular level. Individual administration of GA and propolis reduced the effects on the studied parameters to a degree. Interestingly, GA in conjunction with propolis reversed the alterations in all of the variables examined, highlighting the beneficial effects of combined therapy over monotherapy in the alleviation of beryllium‐induced systemic toxicity.
The evolution of aposematism is accompanied by increased diversification
Authors: PRZECZEK Kara , MUELLER Carla , VAMOSI Steven M.
Published: September 2008

Although the use of distinct colors to indicate unprofitability to predators (i.e. aposematism) is commonly thought of as an adaptation, our knowledge of its macroevolutionary effects is limited. Because aposematism is expected to decrease attacks by predators, we hypothesized that aposematic lineages should be larger on average than their non‐aposematic sister groups because of the decreased probability of extinction and/or increased probability of speciation (i.e. increased diversification). The results of our sister‐group analysis are consistent with the hypothesis that the evolution of aposematism is accompanied by increased diversification of lineages, with the aposematic focal group having more species in 11 of 14 pairs of sister groups. Despite the apparent advantages of reduced predation risk on diversification rates, the evolution of aposematism is relatively rare and reversions to a cryptic state are not uncommon. In addition to the difficulties in evolving a trait that initially decreases the survivorship of prey among naive predators, we discuss other factors that may limit the apparent prevalence and success of aposematism. It is hoped that the results of our analysis will encourage further analyses of the phylogenetic relationships among aposematic groups and their relatives, and of the evolutionary time scales over which the benefits of aposematism are the greatest to lineages with this condition.
Genetic structure of the oriental white stork (Ciconia boyciana): implications for a breeding colony in a non‐breeding area
Authors: ZAN Shuting , ZHOU Lizhi , JIANG Hao , ZHANG Baowei , WU Zhi'an , HOU Yinxu
Published: September 2008

The oriental white stork (Ciconia boyciana) is a threatened species, and their numbers are still in decline due to habitat loss and poaching. China is a breeding and main wintering area for this animal and in recent years some individuals have been found breeding in wintering areas and at some stopover sites. These new breeding colonies are an exciting sign, however, little is understood of the genetic structure of this species. Based on the analysis of a 463‐bp mitochondrial DNA (mtDNA) control region, we investigated the genetic structure and genetic diversity of 66 wild oriental white storks from a Chinese population. We analyzed the sequences of 66 storks obtained in this study and the data of 17 storks from a Japanese population. Thirty‐seven different haplotypes were detected among the 83 samples. An analysis of molecular variance showed a significant population subdivision between the two populations (FST= 0.316, P < 0.05). However, the phylogenetic analysis revealed that the samples from the different populations did not form separate clusters and that there were genetic exchanges between the two populations. Compared with the Japanese population, the Chinese population had a relatively higher genetic diversity with a haplotype diversity (hπ SD) of 0.953 ± 0.013 and a nucleotide diversity (π± SD) of 0.013 ± 0.007. The high haplotype diversity and low nucleotide diversity indicate that this population might be in a rapidly increasing period from a small effective population. A neighbor‐joining tree analysis indicated that genetic exchange had occurred between the newly arisen southern breeding colony and the northern breeding colony wintering in the middle and lower Yangtze River floodplain. These results have important implications for the conservation of the oriental white stork population in China.
Genetic population structure of red snapper (Lutjanus malabaricus) and orange‐spotted grouper (Epinephelus coiodes) in Brunei and Sabah
Authors: SULAIMAN Zohrah H. , ABDUL RAHMAN Khadijah H. , YING Teo Y. , TAHA Hussein H. , MUHD TAHA NurQistina H.
Published: September 2008

The genetic population structure of red snapper Lutjanus malabaricus and orange‐spotted grouper Epinephelus coiodes in Brunei and Sabah was investigated using allozyme electrophoresis. Samples were collected from three sites in Brunei for E. coiodes and from three sites in Brunei and Sabah for L. malabaricus. A total of 22 loci and 16 loci were scored, respectively. The index of fixation (FST) for the E. coiodes population was 0.176 but, in general, it lacked within‐population structuring. The FST was particularly high between Brunei Bay/Jerudong and Brunei Bay/ Kuala Belait, suggesting genetic subdivision on a small spatial scale. Isolation of Brunei Bay from the South China Sea may constrain the movement of adult fishes and larval dispersal, thereby reducing homogeneity among subpopulations. All variable loci for E. coiodes were in Hardy‐Weinberg equilibrium except for MDH* and GTDHP* (P < 0.01), in which two subpopulations showed an excess of heterozygotes (P < 0.01). The study on the L. malabaricus population showed a heterozygote deficit of approximately 60% in variable loci (FST genetic variation within population = 0.45; P < 0.05); however, the mean observed heterozygosity for the population far exceeded L. malabaricus populations in Australia and Indonesia. A FST value of 0.076 revealed moderate genetic differentiation among subpopulations of L. malabaricus. The genotypes were likely to be drawn from the same distribution in Jerudong and Kuala Belait. This study infers that sustainable management of snapper and grouper resources in Brunei waters must take into account the presence of a single stock and two stocks, respectively.
Sex ratio variation and sex determination in the mallee dragon Ctenophorus fordi
Authors: ULLER Tobias , ODIERNA Gaetano , OLSSON Mats
Published: September 2008

Recent evidence suggests that many Australian agamids show temperature‐dependent sex determination (TSD) with variation in sex determining mechanisms among closely related taxa. However, as shown in other vertebrates, sex ratios can also be influenced by genetic or phenotypic differences among females in their propensity to produce sons or daughters, and these influences might confound any thermal effects of incubation per se. To address these issues, we investigated the determinants of sex ratios in the mallee dragon Ctenophorus fordi, together with a detailed analysis of karyotypes. There was no detectable variation in sex ratios arising from variation among females, clutches or incubation temperatures, which might indicate genetic sex determination for this species. However, there was no evidence of cytologically distinct sex chromosomes using standard banding techniques. The sex ratio pattern in C. fordi strongly contrasts with the results for the congener Ctenophorus pictus, where sex ratios show variation among females. Thus, Australian agamids offer promising opportunities to address fundamental issues in sex ratio biology.
Negotiating the Dependency/Nurturance Tightrope: Dilemmas of Motherhood and Disability*
Authors: MALACRIDA CLAUDIA
Published: September 2008

La féminité normative place les mères dans une situation difficile, entre la dépendance et la tendance à se dévouer; d'un côté, les bonnes mères devraient être dépendantes dans une relation avec un mäle pourvoyeur. Inversement, elles devraient fournir de bons soins par un maternage actif, habile ainsi que par leur engagement. Cette condition pose des défis aux femmes ayant une incapacité et dont la dépendance à l'égard d'un partenaire masculin peut entrainer de la vulnérabilite par rapport à l'abus, alors que de la dépendance envers l'Etat peut découler de la pauvreté et de la surveillance. L'auteure explore les dilemmes que les mères handicapées rencontrent pour concilier leur position de dépendance par rapport aux besoins de leurs enfants d'etre maternés. Compliquant les conceptions négatives de la dépendance, plusieurs femmes ont décrit comment certaines relations de dépendance leur ont apporté, a elles et à leurs enfants, des réseaux positifs de soutien.

Normative femininity offers mothers a tightrope of nurturance and dependency. On the one hand, good mothers should be dependent through a relationship with a male provider. Conversely, they should provide nurturance through active, involved and expert mothering. This tightrope poses challenges to women with disabilities whose dependency on male partners can bring vulnerability to abuse, while dependency on the state can result in poverty and surveillance. This article explores the dilemmas disabled mothers face, reconciling their position of dependency against their children's need for nurturance. Complicating negative conceptions of dependency, many women described how some relations of dependency provided them and their children with positive networks of support.
Acyclic Calabi–Yau categories
Authors: Keller Bernhard , Reiten Idun
Published: September 2008

We prove a structure theorem for triangulated Calabi–Yau categories: an algebraic 2-Calabi–Yau triangulated category over an algebraically closed field is a cluster category if and only if it contains a cluster-tilting subcategory whose quiver has no oriented cycles. We prove a similar characterization for higher cluster categories. As an application to commutative algebra, we show that the stable category of maximal Cohen–Macaulay modules over a certain isolated singularity of dimension 3 is a cluster category. This implies the classification of the rigid Cohen–Macaulay modules first obtained by Iyama and Yoshino. As an application to the combinatorics of quiver mutation, we prove the non-acyclicity of the quivers of endomorphism algebras of cluster-tilting objects in the stable categories of representation-infinite preprojective algebras. No direct combinatorial proof is known as yet. In the appendix, Michel Van den Bergh gives an alternative proof of the main theorem by appealing to the universal property of the triangulated orbit category.
Caractérisation des exemples de Lattès et de Kummer
Authors: Cantat Serge
Published: September 2008

Lattès and Kummer examples are rational transformations of compact kähler manifolds that are covered by an affine transformation of a compact torus. We present a few ergodic characteristic properties of these examples. The main results concern the case of surfaces.
Hilbert’s 14th problem over finite fields and a conjecture on the cone of curves
Authors: Totaro Burt
Published: September 2008

We give the first examples over finite fields of rings of invariants that are not finitely generated. (The examples work over arbitrary fields, for example the rational numbers.) The group involved can be as small as three copies of the additive group. The failure of finite generation comes from certain elliptic fibrations or abelian surface fibrations having positive Mordell–Weil rank. Our work suggests a generalization of the Morrison–Kawamata cone conjecture on Calabi–Yau fiber spaces to klt Calabi–Yau pairs. We prove the conjecture in dimension two under the assumption that the anticanonical bundle is semi-ample.
Pressure Loss and Heat Transfer Characterization of a Cam-Shaped Cylinder at Different Orientations
Authors: Nouri-Borujerdi A. , Lavasani Arash M.
Published: September 2008

Pressure drag coefficient and heat transfer are experimentally investigated around a single noncircular cylinder in cross-flow under angle of attack 0 deg<α<360 deg and Reynolds number 1.5×104<Reeq<4.8×104 based on equivalent diameter of a circular cylinder. The results show that the trend of pressure drag coefficient against the angle of attack has a wavy shape but the wavy trend of the Nusselt number is smoother relative to the drag coefficient behavior. It is found that for l∕Deq=0.4 and over the whole range of the Reynolds number, the pressure drag coefficient has a minimum value of about CD=0.4 at α=30 deg, 180 deg, and 330 deg and a maximum value of about CD=0.9 at α=90 deg and 270 deg. The corresponding value of the mean Nusselt number to that of the equivalent circular tube is 1.05<Nu¯cam∕Nu¯cir<1.08 at α=90 deg and 270 deg as well as 0.87<Nu¯cam∕Nu¯cir<0.92 at α=30 deg and 180 deg.
Investigation of Heat Transfer and Pressure Drop of an Impinging Jet in a Cross-Flow for Cooling of a Heated Cube
Authors: Rundström D. , Moshfegh B.
Published: September 2008

The objective of this study is to investigate the thermal performance and the cost measured in pressure drops of a targeted cooling system with use of an impinging jet in combination with a low-velocity channel flow on a heated wall-mounted cube. The effects of the Reynolds numbers of the impinging jet and the cross-flow, as well as the distance between the top and bottom plates, are investigated. A steady-state 3D computational fluid dynamics model was developed with use of a Reynolds stress model as turbulence model. The geometrical case is a channel with a heated cube in the middle of the base plate and two inlets, one horizontal channel flow and one vertical impinging jet. The numerical model was validated against experimental data with a similar geometrical setup. The velocity field was measured by particle image velocimetry and the surface temperature was measured by an infrared imaging system. This case results in a very complex flow structure where several flow-related phenomena influence the heat transfer rate and the pressure drops. The average heat transfer coefficients on each side of the cube and the pressure loss coefficients are presented; correlations for the average heat transfer coefficient on the cube and the pressure loss coefficients are created.
Analytic Solution of Three-Dimensional Viscous Flow and Heat Transfer Over a Stretching Flat Surface by Homotopy Analysis Method
Authors: Mehmood Ahmer , Ali Asif
Published: September 2008

In this paper heat transfer in an electrically conducting fluid bonded by two parallel plates is studied in the presence of viscous dissipation. The plates and the fluid rotate with constant angular velocity about a same axis of rotation where the lower plate is a stretching sheet and the upper plate is a porous plate subject to constant injection. The governing partial differential equations are transformed to a system of ordinary differential equations with the help of similarity transformation. Homotopy analysis method is used to get complete analytic solution for velocity and temperature profiles. The effects of different parameters are discussed through graphs.
Heat Transfer in Mini∕Microchannels With Combustion: A Simple Analysis for Application in Nonintrusive IR Diagnostics
Authors: Veeraragavan Ananthanarayanan , Cadou Christopher P.
Published: September 2008

An analytical solution for the temperature distribution in 2D laminar reacting flow between closely spaced parallel plates is derived as part of a larger effort to develop a nonintrusive technique for measuring gas temperature distributions in millimeter and submillimeter scale channel flows. The results show that the exact solution, a Fourier series, which is a function of the Peclet number, is approximated by second and fourth order polynomial fits to an R2 value of almost unity for both fits. The slopes of the temperature near the wall (heat fluxes) are captured to within 20% of the exact solution using a second order polynomial and to within 2% of the exact solution using a fourth order polynomial. The fits are used in a nonintrusive Fourier transform infrared spectroscopy technique and enable one to infer the temperature distribution along an absorbing gas column from the measured absorption spectrum. The technique is demonstrated in a silicon-walled microcombustor.
Effect of Nonuniform Stack Compression on Proton Exchange Membrane Fuel Cell Temperature Distributions
Authors: Fekrazad N. , Bergman T. L.
Published: September 2008

A three-dimensional model is used to predict the power output and internal temperature distribution of a small proton exchange membrane fuel cell stack. Of particular interest is the influence of nonuniform stack compression on thermal conditions inside the fuel cell. A dimensionless membrane isothermality is correlated with a dimensionless compressive load distribution, suggesting that similar relationships may be developed for other fuel cell geometries. Fuel cell performance, in terms of minimizing temperature variations inside the device, can be enhanced by application of nonuniform stack compression.
Computational Analysis of Surface Curvature Effect on Mist Film-Cooling Performance
Authors: Li Xianchang , Wang Ting
Published: September 2008

Air-film cooling has been widely employed to cool gas turbine hot components, such as combustor liners, combustor transition pieces, turbine vanes, and blades. Studies with flat surfaces show that significant enhancement of air-film cooling can be achieved by injecting water droplets with diameters of 5–10 μm into the coolant airflow. The mist/air-film cooling on curved surfaces needs to be studied further. Numerical simulation is adopted to investigate the curvature effect on mist/air-film cooling, specifically the film cooling near the leading edge and on the curved surfaces. Water droplets are injected as dispersed phase into the coolant air and thus exchange mass, momentum, and energy with the airflow. Simulations are conducted for both 2D and 3D settings at low laboratory and high operating conditions. With a nominal blowing ratio of 1.33, air-only adiabatic film-cooling effectiveness on the curved surface is lower than on a flat surface. The concave (pressure) surface has a better cooling effectiveness than the convex (suction) surface, and the leading-edge film cooling has the lowest performance due to the main flow impinging against the coolant injection. By adding 2% (weight) mist, film-cooling effectiveness can be enhanced approximately 40% at the leading edge, 60% on the concave surface, and 30% on the convex surface. The leading edge film cooling can be significantly affected by changing of the incident angle due to startup or part-load operation. The film cooling coverage could switch from the suction side to the pressure side and leave the surface of the other part unprotected by the cooling film. Under real gas turbine operating conditions at high temperature, pressure, and velocity, mist-cooling enhancement could reach up to 20% and provide a wall cooling of approximately 180 K.
Liquid Single-Phase Flow in an Array of Micro-Pin-Fins—Part II: Pressure Drop Characteristics
Authors: Qu Weilin , Siu-Ho Abel
Published: September 2008

This Technical Brief is Part II of a two-part study concerning water single-phase pressure drop and heat transfer in an array of staggered micro-pin-fins. This brief reports the pressure drop results. Both adiabatic and diabatic tests were conducted. Six previous friction factor correlations for low Reynolds number (Re<1000) flow in conventional and micro-pin-fin arrays were examined and found underpredicting the adiabatic data except the correlation by Short et al. (2002, “Performance of Pin Fin Cast Aluminum Coldwalls, Part 1: Friction Factor Correlation,” J. Thermophys. Heat Transfer, 16(3), pp. 389–396), which overpredicts the data. A new power-law type of correlation was developed, which showed good agreement with both adiabatic and diabatic data.
Numerical Investigation of the Linear Stability of a Free Convection Boundary Layer Flow Using a Thermal Disturbance With a Slowly Increasing Frequency
Authors: Paul Manosh C. , Rees D. Andrew S.
Published: September 2008

Numerical simulations are performed to investigate the linear stability of a two-dimensional incompressible free convection flow induced by a vertical semi-infinite heated flat plate. A small-amplitude local temperature disturbance with a slowly increasing frequency is introduced on the surface near to the leading edge in order to generate disturbance waves within the boundary layer. The aim is to compare the response of the thermal boundary layer with that obtained by selecting discrete disturbance frequencies. In the present study, air is considered to be the working fluid for which the value of the Prandtl number is taken to be Pr=0.7. The computational results show that the disturbance decays initially until it reaches a critical distance, which depends on the current frequency of the disturbance. Thereafter the disturbance grows, but the growth rate also depends on the effective frequency of the disturbance. Comparisons with previous work using constant disturbance frequencies are given, and it is shown that the sine-sweep technique is an effective method for analyzing the instability of convectively unstable boundary layers.
Ab Initio Molecular Dynamics Study of Nanoscale Thermal Energy Transport
Authors: Luo Tengfei , Lloyd John R.
Published: September 2008

Ab initio molecular dynamics, which employs density functional theory, is used to study thermal energy transport phenomena in nanoscale structures. Thermal equilibration in multiple thin layer structures with thicknesses less than 1 nm per layer is simulated. Different types of layer combinations are investigated. Periodic boundary conditions in all directions are used in all cases. Two neighboring layers are first set to different temperatures using Nosé–Hoover thermostats, and then the process of energy equilibration is simulated with a “free run” (without any thermostat controlling the temperatures). The temperature evolutions in the two neighboring layers are computed. The atomic vibration power spectra are calculated and used to explain the phenomena observed in the simulation.
Evaporative Thermal Performance of Vapor Chambers Under Nonuniform Heating Conditions
Authors: Chang Je-Young , Prasher Ravi S. , Prstic Suzana , Cheng P. , Ma H. B.
Published: September 2008

This paper reports the test results of vapor chambers using copper post heaters and silicon die heaters. Experiments were conducted to understand the effects of nonuniform heating conditions (hot spots) on the evaporative thermal performance of vapor chambers. In contrast to the copper post heater, which provides ideal heating, a silicon chip package was developed to replicate more realistic heat source boundary conditions of microprocessors. The vapor chambers were tested for hot spot heat fluxes as high as 746 W/cm2. The experimental results show that evaporator thermal resistance is not sensitive to nonuniform heat conditions, i.e., it is the same as in the uniform heating case. In addition, a model was developed to predict the effective thickness of a sintered-wick layer saturated with water at the evaporator. The model assumes that the pore sizes in the sintered particle wick layer are distributed nonuniformly. With an increase of heat flux, liquid in the larger size pores are dried out first, followed by drying of smaller size pores. Statistical analysis of the pore size distribution is used to calculate the fraction of the pores that remain saturated with liquid at a given heat flux condition. The model successfully predicts the experimental results of evaporative thermal resistance of vapor chambers for both uniform and nonuniform heat fluxes.
Investigation of Thermal Accommodation Coefficients in Time-Resolved Laser-Induced Incandescence
Authors: Daun K. J. , Smallwood G. J. , Liu F.
Published: September 2008

Accurate particle sizing through time-resolved laser-induced incandescence (TR-LII) requires knowledge of the thermal accommodation coefficient, but the underlying physics of this parameter is poorly understood. If the particle size is known a priori, however, TR-LII data can instead be used to infer the thermal accommodation coefficient. Thermal accommodation coefficients measured between soot and different monatomic and polyatomic gases show that the accommodation coefficient increases with molecular mass for monatomic gases and is lower for polyatomic gases. This latter result indicates that surface energy is accommodated preferentially into translational modes over internal modes for these gases.
Thermal Management of Low Profile Electronic Equipment Using Radial Fans and Heat Sinks
Authors: Walsh Ed , Walsh Pat , Grimes Ronan , Egan Vanessa
Published: September 2008

There is an increasing need for low profile thermal management solutions for applications in the range of 5–10W, targeted at portable electronic devices. This need is emerging due to enhanced power dissipation levels in portable electronics, such as mobile phones, portable gaming machines, and ultraportable personal computers. This work focuses on the optimization of such a solution within the constraints of the profile and footprint area. A number of fan geometries have been investigated where both the inlet and exit rotor angles are varied relative to the heat conducting fins on a heat sink. The ratio of the fan diameter to the heat sink fin length was also varied. The objective was to determine the optimal solution from a thermal management perspective within the defined constraints. The results show a good thermal performance and highlight the need to develop the heat sink and fan as an integrated thermal solution rather than in isolation as is the traditional methodology. An interesting finding is that the heat transfer scales are in line with turbulent rather than laminar correlations despite the low Reynolds number. It is also found that while increasing the pumping power generally improves the thermal performance, only small gains are achieved for relatively large pumping power increases. This is important in optimizing portable systems where reduced power consumption is a competitive advantage in the marketplace.
Natural Convection Heat Transfer Enhancements From a Cylinder Using Porous Carbon Foam: Experimental Study
Authors: Jamin Yorwearth L. , Mohamad A. A.
Published: September 2008

The main objective of this experimental study is to quantify and compare the heat transfer enhancement of carbon foam and aluminum fins in natural convection. The study measures steady state heat transfer from a heated vertical pipe, with and without porous medium. The largest increase in Nusselt number was achieved by a solid carbon foam sleeve, which was about 2.5 times greater than a bare copper pipe.
Role of the N-Terminal Amino Acid of
Bacillus anthracis
Lethal Factor in Lethal Toxin Cytotoxicity and Its Effect on the Lethal Toxin Neutralization Assay
Authors: Verma Anita , Wagner Leslie , Stibitz Scott , Nguyen Nga , Guerengomba Flor , Burns Drusilla L.
Published: September 2008

The cytotoxic activity of lethal factor (LF), a critical reagent used in the cell-based lethal toxin neutralization assay to assess anthrax vaccines, was shown to depend on the identity of its N-terminal amino acid, which plays a role in the targeting of LF to the proteasome for degradation. These results demonstrate that care must be taken to ensure that LF preparations used in standardized cell-based assays are not altered at their N-terminal ends.
Exposure of Cord Blood toMycobacterium bovisBCG Induces an Innate Response but Not a T-Cell Cytokine Response
Authors: Watkins M. L. V. , Semple P. L. , Abel B. , Hanekom W. A. , Kaplan G. , Ress S. R.
Published: September 2008

Despite routine vaccination withMycobacterium bovisbacillus Calmette-Guérin (BCG) soon after birth, tuberculosis in babies and adults remains epidemic in South Africa. The immune responses of the naïve newborn child and how they are affected by vaccination with BCG are as yet not fully understood. Immunity during pregnancy and in healthy human newborns may be skewed toward type 2 cytokine production; however, it is type 1 cytokines that are required for protection againstM. tuberculosisinfection. To better understand neonatal cytokine responses prior to and following exposure to mycobacteria, we have collected cord blood and peripheral blood samples and evaluated the cytokine response following ex vivo incubation with BCG. Gamma interferon (IFN-γ), interleukin 10 (IL-10), IL-12, and low levels of IL-13 and IL-5 but no IL-4 were secreted into the culture supernatant of cord blood mononuclear cells. Intracellular staining showed that IL-10 and IL-12 were produced by monocytes and that IFN-γ was produced by natural killer (NK) cells but not by CD4+or CD8+T cells. In contrast, in the peripheral blood samples collected from babies 13 weeks post-BCG vaccination, IFN-γ was detected within CD4+and CD8+cells. Taken together, the data suggest a central role for Th1 cytokines in naïve as well as BCG-vaccinated neonates in the protective immune response to tuberculosis. NK cell-derived IFN-γ produced in naïve neonates likely plays a key protective role via monocyte activation and the priming of a subsequent adaptive Th1 response.
Kinetics of Decline of Maternal Measles Virus-Neutralizing Antibodies in Sera of Infants in France in 2006
Authors: Gagneur Arnaud , Pinquier Didier , Aubert Marie , Balu Laurent , Brissaud Olivier , De Pontual Loïc , Gras Le Guen Christèle , Hau-Rainsard Isabelle , Mory Olivier , Picherot Georges , Stephan Jean-Louis , Cohen Bernard , Caulin Evelyne , Soubeyrand Benoît , Reinert Philippe
Published: September 2008

The optimal age for measles vaccination is an important health issue, since maternal antibodies may neutralize the vaccine antigen before a specific immune response develops, while delaying vaccination may increase the risk of complicated diseases in infants. However, measles vaccination impacts the duration of protection afforded by transplacental transfer of maternal antibodies: vaccination-induced maternal antibodies disappear faster than disease-induced antibodies. In order to maintain protection against measles in infants, it is important to monitor the dynamics of this phenomenon in vaccinated populations. To assess the current situation in France, a multicenter, prospective seroepidemiological study was conducted in seven French hospitals between October 2005 and January 2007. Maternal measles antibody concentrations from 348 infants 0 to 15 months old were measured using the plaque reduction neutralization assay. Geometric mean concentrations and the percentage of infants with maternal measles antibody concentrations above the protection threshold (≥120 mIU/ml) were assessed according to age. Results show that after more than 20 years of routine measles vaccination in France, maternal measles-neutralizing antibodies decrease dramatically in French infants by 6 months of age, from 1,740 mIU/ml for infants 0 to 1 month old to 223 mIU/ml for infants 5 to 6 months old, and that 90% of infants are not protected against measles after 6 months of age. Infant protection against measles could be optimized both by increasing herd immunity through an increased vaccine coverage and by lowering the age of routine vaccination from 12 to 9 months.
Potentially Exposed but Uninfected Individuals Produce Cytotoxic and Polyfunctional Human Immunodeficiency Virus Type 1-Specific CD8+T-Cell Responses Which Can Be Defined to the Epitope Level
Authors: Erickson A. L. , Willberg C. B. , McMahan V. , Liu A. , Buchbinder S. P. , Grohskopf L. A. , Grant R. M. , Nixon D. F.
Published: September 2008

We measured CD8+T-cell responses in 12 potentially exposed but uninfected men who have sex with men by using cytokine flow cytometry. Four of the individuals screened exhibited polyfunctional immune responses to human immunodeficiency virus type 1 Gag or Vif. The minimum cytotoxic T lymphocyte epitope was mapped in one Gag responder.
Chronic Intestinal Nematode Infection Exacerbates ExperimentalSchistosoma mansoniInfection
Authors: Bickle Quentin D. , Solum Julie , Helmby Helena
Published: September 2008

Mixed-parasite infections are common in many parts of the world, but little is known of the effects of concomitant parasite infections on the immune response or on disease progression. We have investigated the in vivo effects of a chronic gastrointestinal nematode infection on the infectivity and development of the immune response against the common trematode helminthSchistosoma mansoni. The data show that mice carrying an established chronicTrichuris murisinfection and coinfected withS. mansoni, had significantly higherS. mansoniworm burdens than mice without coinfection. The increase inS. mansoniworm burden was accompanied by a higher egg burden in the liver. Kinetic analysis ofS. mansoniestablishment indicate reduced trapping ofS. mansonilarvae during skin-to-lung migration, withT. muris-induced alterations in lung cytokine expression and inflammatory foci surrounding lung-stage schistosomula, suggesting that the immunomodulatory effects of chronicT. murisinfection elicited at the gut mucosal surface extend to other organs and perhaps specifically to other mucosal surfaces. The data show that a preexisting chronic gastrointestinal nematode infection facilitates the survival and migration ofS. mansonischistosomula to the portal system, and as a result, increases the egg burden and associated pathology ofS. mansoniinfection.
Role of T Cells in Virus Control and Disease after Infection with Pneumonia Virus of Mice
Authors: Frey Stefanie , Krempl Christine D. , Schmitt-Gräff Annette , Ehl Stephan
Published: September 2008

Infection of mice with pneumonia virus of mice (PVM) is used as a natural host experimental model for studying the pathogenesis of infection with the closely related human respiratory syncytial virus. We analyzed the contribution of T cells to virus control and pathology after PVM infection. Control of a sublethal infection with PVM strain 15 in C57BL/6 mice was accompanied by a 100-fold increase in pulmonary cytotoxic T lymphocytes, 20% of which were specific for PVM. T-cell-deficient mice failed to eliminate PVM and became virus carriers in the absence of the clinical or histopathological signs of pneumonia that occurred after infection of control mice. Mice with limited T-cell numbers did not achieve virus control without weight loss, indicating that T-cell-mediated virus control was closely linked to immunopathology. Both CD4 and CD8 T cells independently contributed to virus elimination and disease. Virus control and disease were similar in the absence of perforin, gamma interferon, or tumor necrosis factor alpha. Interestingly, disease and mortality after lethal high-dose PVM infection were independent of T cells. These data illustrate a key role for T cells in control of PVM infection and demonstrate that both T-cell-dependent and -independent pathways contribute to disease in a viral dose-dependent fashion.
Equine Herpesvirus 1 Entry via Endocytosis Is Facilitated by αV Integrins and an RSD Motif in Glycoprotein D
Authors: Van de Walle Gerlinde R. , Peters Sarah T. , VanderVen Brian C. , O'Callaghan Dennis J. , Osterrieder Nikolaus
Published: September 2008

Equine herpesvirus 1 (EHV-1) is a member of the
Alphaherpesvirinae
, and its broad tissue tropism suggests that EHV-1 may use multiple receptors to initiate virus entry. EHV-1 entry was thought to occur exclusively through fusion at the plasma membrane, but recently entry via the endocytic/phagocytic pathway was reported for Chinese hamster ovary cells (CHO-K1 cells). Here we show that cellular integrins, and more specifically those recognizing RGD motifs such as αVβ5, are important during the early steps of EHV-1 entry via endocytosis in CHO-K1 cells. Moreover, mutational analysis revealed that an RSD motif in the EHV-1 envelope glycoprotein D (gD) is critical for entry via endocytosis. In addition, we show that EHV-1 enters peripheral blood mononuclear cells predominantly via the endocytic pathway, whereas in equine endothelial cells entry occurs mainly via fusion at the plasma membrane. Taken together, the data in this study provide evidence that EHV-1 entry via endocytosis is triggered by the interaction between cellular integrins and the RSD motif present in gD and, moreover, that EHV-1 uses different cellular entry pathways to infect important target cell populations of its natural host.
Borna Disease Virus P Protein Affects Neural Transmission through Interactions with Gamma-Aminobutyric Acid Receptor-Associated Protein
Authors: Peng Guiqing , Yan Yan , Zhu Chengliang , Wang Shiqun , Yan Xiaohong , Lu Lili , Li Wei , Hu Jing , Wei Wei , Mu Yongxin , Chen Yanni , Feng Yong , Gong Rui , Wu Kailang , Zhang Fengmin , Zhang Xiaolian , Zhu Ying , Wu Jianguo
Published: September 2008

Borna disease virus (BDV) is one of the infectious agents that causes diseases of the central nervous system in a wide range of vertebrate species and, perhaps, in humans. The phosphoprotein (P) of BDV, an essential cofactor of virus RNA-dependent RNA polymerase, is required for virus replication. In this study, we identified the gamma-aminobutyric acid receptor-associated protein (GABARAP) with functions in neurobiology as one of the viral P protein-interacting cellular factors by using an approach of phage display-based protein-protein interaction analysis. Direct binding between GABARAP and P protein was confirmed by coimmunoprecipitation, protein pull-down, and mammalian two-hybrid analyses. GABARAP originally was identified as a linker between the gamma-aminobutyric acid receptor (GABAR) and the microtubule to regulate receptor trafficking and plays important roles in the regulation of the inhibitory neural transmitter gamma-aminobutyric acid (GABA). We showed that GABARAP colocalizes with P protein in the cells infected with BDV or transfected with the P gene, which resulted in shifting the localization of GABARAP from the cytosol to the nucleus. We further demonstrated that P protein blocks the trafficking of GABAR, a principal GABA-gated ion channel that plays important roles in neural transmission, to the surface of cells infected with BDV or transfected with the P gene. We proposed that during BDV infection, P protein binds to GABARAP, shifts the distribution of GABARAP from the cytoplasm to the nucleus, and disrupts the trafficking of GABARs to the cell membranes, which may result in the inhibition of GABA-induced currents and in the enhancement of hyperactivity and anxiety.