bluuebunny/crossref_metadata_2025 huggingface dataset:
Lymphatic fluid: exchange mechanisms and regulation
Authors: Huxley Virginia H. , Scallan Joshua
Published: April 2011

Abstract  Regulation of fluid and material movement between the vascular space of microvessels penetrating functioning organs and the cells therein has been studied extensively. Unanswered questions as to the regulatory mechanisms and routes remain. Significantly less is known about the lymphatic vascular system given the difficulties in seeing, no less isolating, these vessels lying deeper in these same tissues. It has become evident that the exchange microvasculature is not simply a passive biophysical barrier separating the vascular and interstitial compartments but a dynamic, multicellular structure subject to acute regulation and chronic adaptation to stimuli including inflammation, sepsis, diabetes, injury, hypoxia and exercise. Similarly lymphatic vessels range, in their simplest form, from lymphatic endothelium attached to the interstitial matrix, to endothelia and phasic lymphatic smooth muscle that act as Starling resistors. Recent work has demonstrated that among the microvascular lymphatic elements, the collecting lymphatics have barrier properties similar to venules, and thus participate in exchange. As with venules, vasoactive agents can alter both the permeability and contractile properties thereby setting up previously unanticipated gradients in the tissue space and providing potential targets for the pharmacological prevention and/or resolution of oedema.
A New Intermittent Aspirated Probe for the Measurement of Stagnation Quantities in High Temperature Gases
Authors: Massini Michela , Miller Robert J. , Hodson Howard P.
Published: April 2011

This paper presents the design, manufacture, and testing of a new probe for the measurement of temperature and pressure in engine environments. The probe consists of a choked nozzle located in the flow and a system downstream including a cooler, a flow measuring device, and a valve. It operates in two modes: In the first mode the valve is open, the probe is aspirated, and the nozzle is choked. The mass flow through the probe is measured using instrumentation placed downstream of the cooler, so that it does not have contact with the hot flow. In the second mode, the valve is closed, and the stagnation pressure is measured using the same instrumentation downstream the cooler. The total temperature is computed as a derived variable from the measurements of stagnation pressure and mass flow rate. There are a number of advantages of the probe over existing methods of temperature measurement. The measurement inaccuracy due to conduction and radiation errors and calibration drift found in thermocouples is significantly reduced; it can measure both stagnation temperature and pressure, halving the instrumentation costs; it has no wiring or transducer in the sensor head; the system can self-calibrate while located within an engine. This paper describes the design of a probe for use in engine environments. The probe prototype is tested up to 900 K and is shown to have an accuracy of ±6 K.
Effect of Upstream Step on Flat Plate Film-Cooling Effectiveness Using PSP
Authors: Rallabandi Akhilesh P. , Grizzle Joshua , Han Je-Chin
Published: April 2011

The effect of a step positioned upstream of a row of film-cooling holes on the film-cooling effectiveness is studied systematically using the steady state pressure sensitive paint technique. The upstream step effect is studied on four separate hole geometries: simple angled (axial angle of 30 deg) and compound angled (axial angle of 30 deg and compound angle of 45 deg) and cylindrical and fan-shaped film-cooling holes. Each plate considered has seven holes, each hole 4 mm in diameter. The plates with cylindrical holes have a spacing of 3 diameters (12 mm) between the centers of two consecutive holes while the fan-shaped holes have a spacing of 3.75 diameters (15 mm). Three different step heights (12.5%d, 25%d, and 37.5%d) are studied. The effect of the width of the step is also studied; the distance of the step upstream of the hole and the positioning of the step downstream of the film-cooling hole. Four separate blowing ratios are reported for all tests: M=0.3, M=0.6, M=1.0, and M=1.5. All studies have been conducted with a mainstream of 25 m/s velocity at an ambient temperature of 22°C. Results indicate an increase in film-cooling effectiveness in the region near the hole due to the upstream step for all the plates considered. This increase due to the step is found to be most significant in the case of compound angled cylindrical holes and least significant in the case of simple angled fan-shaped holes.
Surface Functionalization Mechanisms of Enhancing Heat Transfer at Solid-Liquid Interfaces
Authors: Goicochea Javier V. , Hu Ming , Michel Bruno , Poulikakos Dimos
Published: April 2011

Two mechanisms that enhance heat dissipation at solid-liquid interfaces are investigated from the atomistic point of view using nonequilibrium molecular dynamics simulation. The mechanisms include surface functionalization, where –OH terminated headgroups and self-assembled monolayers (SAMs) with different chain lengths are used to recondition and modify the hydrophilicity of silica surface, and vibrational matching between crystalline silica and liquid water, where three-dimensional nanopillars are grown at the interface in the direction of the heat flux with different lengths to rectify the vibrational frequencies of surface atoms. The heat dissipation is measured in terms of the thermal conductance of the solid-liquid interface and is obtained by imposing a one-dimensional heat flux along the simulation domain. A comparison with reported numerical and experimental thermal conductance measurements for similar interfaces indicates that the thermal conductance is enhanced by 1.8–3.2 times when the silica surface is reconditioned with hydrophilic groups. The enhancement is further promoted by SAMs, which results in a 20% higher thermal conductance compared with that of the fully hydroxylated silica surface. Likewise, the presence of nanopillars enhances the interface thermal conductance by 2.6 times compared with a bare surface (without nanopillars). Moreover, for different nanopillar densities, the conductance increases linearly with the length of the pillar and saturates at around 4.26 nm. Changes in the vibrational spectrum of surface atoms and water confinement effects are found to be responsible for the increase in conductance. The modification of surface vibrational states provides a tunable path to enhance heat dissipation, which can also be easily applied to other fluids and interfaces.
The Effect of the Corrugation Rib Angle of Attack on the Fluid Flow and Heat Transfer Characteristics Inside Corrugated Ribbed Passage
Authors: Mohamed A. M. I. , Hoettiba R. , Saif A. M.
Published: April 2011

Heat transfer enhancement using corrugated ribbed passages is one of the common enhancement techniques inside heat exchangers. The present study investigated numerically the effect of the corrugation rib angle of attack on the fluid flow and heat transfer characteristics inside the corrugated ribbed passage. The commercial computational fluid dynamics code PHOENICS 2006 was used to perform the numerical analysis by solving the Navier–Stokes and energy equations. The experimental part of this study was used only to validate the numerical model, and a good agreement between the experimental results and the model was obtained. The flow field characteristics and heat transfer enhancement were numerically investigated for different corrugated rib angles of attack as follows: 90 deg, 105 deg, 120 deg, 135 deg, and 150 deg. The corrugation rib angle of attack has a great effect on the reversed flow zone, the flow reattachments, and the enhancement of the heat transfer coefficient through the duct. The recommended rib angle of attack, which gives the optimum thermohydraulic performance, is found to be between 135 deg and 150 deg. The value of the maximum thermohydraulic performance is about 3.6 for the 150 deg rib angle of attack at a Reynolds number equal to 10,000.
Flow Boiling Heat Transfer Characteristics of a Minichannel up to Dryout Condition
Authors: Ali Rashid , Palm Björn , Maqbool Mohammad H.
Published: April 2011

In this paper, the experimental flow boiling heat transfer results of a minichannel are presented. A series of experiments was conducted to measure the heat transfer coefficients in a minichannel made of stainless steel (AISI 316) having an internal diameter of 1.70 mm and a uniformly heated length of 220 mm. R134a was used as a working fluid, and experiments were performed at two different system pressures corresponding to saturation temperatures of 27°C and 32°C. Mass flux was varied from 50 kg/m2 s to 600 kg/m2 s, and heat flux ranged from 2 kW/m2 to 156 kW/m2. The test section was heated directly using a dc power supply. The direct heating of the channel ensured uniform heating, which was continued until dryout was reached. The experimental results show that the heat transfer coefficient increases with imposed wall heat flux, while mass flux and vapor quality have no considerable effect. Increasing the system pressure slightly enhances the heat transfer coefficient. The heat transfer coefficient is reduced as dryout is reached. It is observed that the dryout phenomenon is accompanied with fluctuations and a larger standard deviation in outer wall temperatures.
Analyzing the Anatomy of Integrin Adhesions
Authors: Byron Adam
Published: April 2011

The spatial organization of integrin adhesions provides insight into their molecular functions.
Sorting the Signals from the Signals in the Noisy Environment of Inflammation
Authors: Muller William A.
Published: April 2011

Neutrophils migrate through inflamed tissue into necrotic tissue by following a restricted set of molecular cues.
Focus Issue: Moving in the Right Direction
Authors: Wong Wei
Published: April 2011

Various signaling pathways enable cells to sense environmental cues and direct their migration accordingly.
Activated by Caspases
Authors: Wong Wei
Published: April 2011

Caspase activity in microglia does not trigger cell death, but rather induces proinflammatory responses.
A Hippo-Sized Heart
Authors: VanHook Annalisa M.
Published: April 2011

Hippo antagonizes Wnt signaling to restrict proliferation of cardiomyocytes, thereby regulating heart size.
MHCs and TLRs
Authors: Foley John F.
Published: April 2011

Major histocompatibility class II molecules promote Toll-like receptor signaling in macrophages and dendritic cells.
Growth or Retraction
Authors: Hines Pamela J.
Published: April 2011

One receptor binds two different types of proteoglycan at the same site but with divergent outcomes.
Characterization of Metallo-β-Lactamase VIM-27, an A57S Mutant of VIM-1 Associated with Klebsiella pneumoniae ST147
Authors: Papagiannitsis C. C. , Kotsakis S. D. , Petinaki E. , Vatopoulos A. C. , Tzelepi E. , Miriagou V. , Tzouvelekis L. S.
Published: April 2011

VIM-27 metallo-β-lactamase, an Ala
57
→ Ser variant of VIM-1, was identified in three
Klebsiella pneumoniae
isolates belonging to sequence type 147.
bla
VIM-27
was part of a class 1 integron carried by non-self-transferable plasmids. Kinetic parameters and MIC determinations indicated that VIM-27 hydrolyzed most β-lactams, especially imipenem and cefoxitin, less effectively than VIM-1.
Horizontal Transfer of the OXA-24 Carbapenemase Gene via Outer Membrane Vesicles: a New Mechanism of Dissemination of Carbapenem Resistance Genes in Acinetobacter baumannii
Authors: Rumbo Carlos , Fernández-Moreira Esteban , Merino María , Poza Margarita , Mendez Jose Antonio , Soares Nelson C. , Mosquera Alejandro , Chaves Fernando , Bou Germán
Published: April 2011

The resistance of
Acinetobacter baumannii
strains to carbapenems is a worrying problem in hospital settings. The main mechanism of carbapenem resistance is the expression of β-lactamases (metalloenzymes or class D enzymes). The mechanisms of the dissemination of these genes among
A. baumannii
strains are not fully understood. In this study we used two carbapenem-resistant clinical strains of
A. baumannii
(AbH12O-A2 and AbH12O-CU3) expressing the plasmid-borne
bla
OXA-24
gene (plasmids pMMA2 and pMMCU3, respectively) to demonstrate that
A. baumannii
releases outer membrane vesicles (OMVs) during
in vitro
growth. The use of hybridization studies enabled us to show that these OMVs harbored the
bla
OXA-24
gene. The incubation of these OMVs with the carbapenem-susceptible
A. baumannii
ATCC 17978 host strain yielded full resistance to carbapenems. The presence of the original plasmids harboring the
bla
OXA-24
gene was detected in strain ATCC 17978 after the transformation of OMVs. New OMVs harboring
bla
OXA-24
were released by
A. baumannii
ATCC 17978 after it was transformed with the original OMV-mediated plasmids, indicating the universality of the process. We present the first experimental evidence that clinical isolates of
A. baumannii
may release OMVs as a mechanism of horizontal gene transfer whereby carbapenem resistance genes are delivered to surrounding
A. baumannii
bacterial isolates.
Dissemination of Multiple Drug Resistance Genes by Class 1 Integrons in Klebsiella pneumoniae Isolates from Four Countries: a Comparative Study
Authors: Roy Chowdhury Piklu , Ingold Ana , Vanegas Natasha , Martínez Elena , Merlino John , Merkier Andrea Karina , Castro Mercedes , González Rocha Gerardo , Borthagaray Graciela , Centrón Daniela , Bello Toledo Helia , Márquez Carolina M. , Stokes H. W.
Published: April 2011

A comparative genetic analysis of 42 clinical
Klebsiella pneumoniae
isolates, resistant to two or more antibiotics belonging to the broad-spectrum β-lactam group, sourced from Sydney, Australia, and three South American countries is presented. The study focuses on the genetic contexts of class 1 integrons, mobilizable genetic elements best known for their role in the rapid evolution of antibiotic resistance among Gram-negative pathogens. It was found that the class 1 integrons in this cohort were located in a number of different genetic contexts with clear regional differences. In Sydney, IS
26
-associated Tn
21-
like transposons on IncL/M plasmids contribute greatly to the dispersal of integron-associated
m
ultiple-
d
rug-
r
esistant (MDR) loci. In contrast, in the South American countries, Tn
1696-
like transposons on an IncA/C plasmid(s) appeared to be disseminating a characteristic MDR region. A range of mobile genetic elements is clearly being recruited by clinically important mobile class 1 integrons, and these elements appear to be becoming more common with time. This in turn is driving the evolution of complex and laterally mobile MDR units and may further complicate antibiotic therapy.
Effects of Fluconazole, Amphotericin B, and Caspofungin on Candida albicans Biofilms under Conditions of Flow and on Biofilm Dispersion
Authors: Uppuluri Priya , Srinivasan Anand , Ramasubramanian Anand , Lopez-Ribot Jose L.
Published: April 2011

We have examined the effect of continuous perfusion with antifungals on
Candida albicans
biofilms under conditions of flow, closely mimicking physiological conditions encountered within patients. Biofilms displayed high levels of resistance to fluconazole, and this antifungal exerted minor effects on dispersion levels. Amphotericin B proved effective in reducing viability of cells within the biofilms and dispersion, but only at high concentrations. Under flow conditions, caspofungin exhibited potent activity against biofilms and drastically reduced biofilm dispersion.
Molecular Mechanism of Renal Tubular Secretion of the Antimalarial Drug Chloroquine
Authors: Müller Fabian , König Jörg , Glaeser Hartmut , Schmidt Ingrid , Zolk Oliver , Fromm Martin F. , Maas Renke
Published: April 2011

The antimalarial drug chloroquine is eliminated to a significant extent by renal tubular secretion. The molecular mechanism of renal chloroquine secretion remains unknown. We hypothesized that organic cation transporter 2 (OCT2) and multidrug and toxin extrusion protein 1 (MATE1), localized in the basolateral and luminal membranes of proximal tubule cells, respectively, are involved in chloroquine transport. The interaction of chloroquine with both transporters was investigated using single-transfected human embryonic kidney 293 (HEK293)-MATE1 cells in uptake experiments and single-transfected Madin-Darby canine kidney II (MDCK)-OCT2 and MDCK-MATE1 cells as well as double-transfected MDCK-OCT2-MATE1 cells grown as polarized monolayers on transwell filters. In HEK293-MATE1 cells, chloroquine competitively inhibited MATE1-mediated metformin uptake (

K
i

= 2.8 μM). Cellular accumulation of chloroquine was significantly lower (
P
< 0.001) and transcellular chloroquine transport was significantly increased (
P
< 0.001) in MDCK-MATE1 and MDCK-OCT2-MATE1 cells compared to vector control cells after basal addition of chloroquine (0.1 to 10 μM). In contrast, no difference in cellular accumulation or transcellular transport of chloroquine was observed between MDCK-OCT2 and vector control cells. In line with an oppositely directed proton gradient acting as a driving force for MATE1, basal-to-apical transport of chloroquine by MDCK-OCT2-MATE1 cells increased with decreasing apical pH from 7.8 to 6.0. Transcellular transport of chloroquine by MDCK-OCT2-MATE1 cells was inhibited by cimetidine, trimethoprim, and amitriptyline. Our data demonstrate that chloroquine is a substrate and potent competitive inhibitor of MATE1, whereas OCT2 seems to play no role in chloroquine uptake. Concomitantly administered MATE1 inhibitors are likely to modify the renal secretion of chloroquine.
Contribution of Lethal Toxin and Edema Toxin to the Pathogenesis of Anthrax Meningitis
Authors: Ebrahimi Celia M. , Sheen Tamsin R. , Renken Christian W. , Gottlieb Roberta A. , Doran Kelly S.
Published: April 2011

Bacillus anthracis
is a Gram-positive spore-forming bacterium that causes anthrax disease in humans and animals. Systemic infection is characterized by septicemia, toxemia, and meningitis, the main neurological complication associated with high mortality. We have shown previously that
B. anthracis
Sterne is capable of blood-brain barrier (BBB) penetration, establishing the classic signs of meningitis, and that infection is dependent on the expression of both major anthrax toxins, lethal toxin (LT) and edema toxin (ET). Here we further investigate the contribution of the individual toxins to BBB disruption using isogenic toxin mutants deficient in lethal factor, ΔLF, and edema factor, ΔEF. Acute infection with
B. anthracis
Sterne and the ΔLF mutant resulted in disruption of human brain microvascular endothelial cell (hBMEC) monolayer integrity and tight junction protein zona occludens-1, while the result for cells infected with the ΔEF mutant was similar to that for the noninfected control. A significant decrease in bacterial invasion of BBB endothelium
in vitro
was observed during infection with the ΔLF strain, suggesting a prominent role for LT in promoting BBB interaction. Further, treatment of hBMECs with purified LT or chemicals that mimic LT action on host signaling pathways rescued the hypoinvasive phenotype of the ΔLF mutant and resulted in increased bacterial uptake. We also observed that toxin expression reduced bacterial intracellular survival by inducing the bulk degradative autophagy pathway in host cells. Finally, in a murine model of anthrax meningitis, mice infected with the ΔLF mutant exhibited no mortality, brain bacterial load, or evidence of meningitis compared to mice infected with the parental or ΔEF strains.
Monocyte Chemoattractant Protein 1 Regulates Pulmonary Host Defense via Neutrophil Recruitment during Escherichia coli Infection
Authors: Balamayooran Gayathriy , Batra Sanjay , Balamayooran Theivanthiran , Cai Shanshan , Jeyaseelan Samithamby
Published: April 2011

Neutrophil accumulation is a critical event to clear bacteria. Since uncontrolled neutrophil recruitment can cause severe lung damage, understanding neutrophil trafficking mechanisms is important to attenuate neutrophil-mediated damage. While monocyte chemoattractant protein 1 (MCP-1) is known to be a monocyte chemoattractant, its role in pulmonary neutrophil-mediated host defense against Gram-negative bacterial infection is not understood. We hypothesized that MCP-1/chemokine (C-C motif) ligand 2 is important for neutrophil-mediated host defense. Reduced bacterial clearance in the lungs was observed in MCP-1−/−mice followingEscherichia coliinfection. Neutrophil influx, along with cytokines/chemokines, leukotriene B4(LTB4), and vascular cell adhesion molecule 1 levels in the lungs, was reduced in MCP-1−/−mice after infection.E. coli-induced activation of NF-κB and mitogen-activated protein kinases in the lung was also reduced in MCP-1−/−mice. Administration of intratracheal recombinant MCP-1 (rMCP-1) to MCP-1−/−mice induced pulmonary neutrophil influx and cytokine/chemokine responses in the presence or absence ofE. coliinfection. Ourin vitromigration experiment demonstrates MCP-1-mediated neutrophil chemotaxis. Notably, chemokine receptor 2 is expressed on lung and blood neutrophils, which are increased uponE. coliinfection. Furthermore, our findings show that neutrophil depletion impairsE. coliclearance and that exogenous rMCP-1 after infection improves bacterial clearance in the lungs. Overall, these new findings demonstrate thatE. coli-induced MCP-1 causes neutrophil recruitment directly via chemotaxis as well as indirectly via modulation of keratinocyte cell-derived chemokine, macrophage inflammatory protein 2, and LTB4.
Estradiol and Progesterone Strongly Inhibit the Innate Immune Response of Mononuclear Cells in Newborns
Authors: Giannoni Eric , Guignard Laurence , Knaup Reymond Marlies , Perreau Matthieu , Roth-Kleiner Matthias , Calandra Thierry , Roger Thierry
Published: April 2011

Newborns are particularly susceptible to bacterial infections due to qualitative and quantitative deficiencies of the neonatal innate immune system. However, the mechanisms underlying these deficiencies are poorly understood. Given that fetuses are exposed to high concentrations of estradiol and progesterone during gestation and at time of delivery, we analyzed the effects of these hormones on the response of neonatal innate immune cells to endotoxin, bacterial lipopeptide, andEscherichia coliand group BStreptococcus, the two most common causes of early-onset neonatal sepsis. Here we show that at concentrations present in umbilical cord blood, estradiol and progesterone are as powerful as hydrocortisone for inhibition of cytokine production by cord blood mononuclear cells (CBMCs) and newborn monocytes. Interestingly, CBMCs and newborn monocytes are more sensitive to the effects of estradiol and progesterone than adult peripheral blood mononuclear cells and monocytes. This increased sensitivity is associated with higher expression levels of estrogen and membrane progesterone receptors but is independent of a downregulation of Toll-like receptor 2 (TLR2), TLR4, and myeloid differentiation primary response gene 88 in newborn cells. Estradiol and progesterone mediate their anti-inflammatory activity through inhibition of the NF-κB pathway but not the mitogen-activated protein kinase pathway in CBMCs. Altogether, these results suggest that elevated umbilical cord blood concentrations of estradiol and progesterone acting on mononuclear cells expressing high levels of steroid receptors contribute to impair innate immune responses in newborns. Therefore, intrauterine exposure to estradiol and progesterone may participate in increasing susceptibility to infection during the neonatal period.
Placental Malaria-Associated Suppression of Parasite-Specific Immune Response in Neonates Has No Major Impact on Systemic CD4 T Cell Homeostasis
Authors: Soulard Valérie , Amadoudji Zin Martin , Fitting Catherine , Ibitokou Samad , Oesterholt Mayke , Luty Adrian J. F. , Perrin René-Xavier , Massougbodji Achille , Deloron Philippe , Bandeira Antonio , Fievet Nadine
Published: April 2011

In areas where
Plasmodium falciparum
is endemic, pregnancy is associated with accumulation of infected red blood cells (RBCs) in the placenta, a condition referred to as placental malaria (PM). Infants born to PM-positive mothers are at an increased risk of malaria, which is putatively related to the transplacental passage of parasite-derived antigens, with consequent tolerization of the fetal immune system. Here we addressed the impact of PM on the regulation of neonatal T cell responses. We found that the frequency of regulatory CD25
+
CD127
−/low
Foxp3
+
CD4
+
T cells was significantly decreased in neonates born to mothers with high levels of
P. falciparum
-induced placental inflammation, consisting mainly of primigravid mothers. However, at the individual level, the ratio between regulatory and effector (CD25
+
CD127
+
Foxp3
−
) CD4
+
T cells was unaffected by PM. In addition, parasite-induced CD4
+
T cell activation and production of interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), and IL-10 were strongly reduced in neonates born to PM-positive mothers. Thus, our results show that active PM at delivery is associated with a marked suppression of
P. falciparum
-specific cellular neonatal immune responses, affecting secretion of both pro- and anti-inflammatory cytokines. Additionally, our results suggest that, as in adults, effector and regulatory CD4
+
T cell populations are tightly coregulated in all neonates, irrespective of the maternal infection status.
Critical Role for CXC Ligand 10/CXC Receptor 3 Signaling in the Murine Neonatal Response to Sepsis
Authors: Cuenca Alex G. , Wynn James L. , Kelly-Scumpia Kindra M. , Scumpia Philip O. , Vila Lizette , Delano Matthew J. , Mathews Clayton E. , Wallet Shannon M. , Reeves Westley H. , Behrns Kevin E. , Nacionales Dina C. , Efron Philip A. , Kunkel Steven L. , Moldawer Lyle L.
Published: April 2011

Previous studies have suggested that neonates rely heavily on innate immunity for their antimicrobial response to bacterial infections. However, the innate immune response by neonates to bacterial infection remains poorly characterized. Here, we show that in a murine model of neonatal polymicrobial sepsis, CXC ligand 10 (CXCL10) concentrations increase in the blood and peritoneum concordant with the peritoneal recruitment of granulocytes and macrophages. Additionally, CXC receptor 3 (CXCR3) expression on elicited peritoneal macrophages and granulocytes increases following sepsis. Blockade of CXCL10 worsens not only recruitment and phagocytic function of peritoneal granulocytes and macrophages but also survival. Deletion of CXCR3 also significantly increases mortality to a septic challenge. Finally, we demonstrate that the protective adjuvant effect of pretreatment with a Toll-like receptor 4 agonist to neonatal sepsis is dependent on an endogenous CXCL10 response and that pretreatment of neonates with CXCL10 can also significantly improve macrophage and granulocyte function and modestly improve outcome to polymicrobial sepsis. Together, these data suggest a critical role for CXCL10 signaling during neonatal sepsis.
Basaltic to andesitic volcaniclastic rocks in the Blake River Group, Abitibi Greenstone Belt: 1. Mode of emplacement in three areas1This article is a companion paper to Ross et al. 2011. Basaltic to andesitic volcaniclastic rocks in the Blake River Group, Abitibi Greenstone Belt: 2. Origin, geochemistry, and geochronology. Canadian Journal of Earth Sciences, 48: this issue.2MRNF Contribution BEGQ 8439-2010/2011-1. Natural Resources Canada, Earth Science Sector Contribution 20100253.
Authors: Ross Pierre-Simon , Goutier Jean , Mercier-Langevin Patrick , Dubé Benoît
Published: April 2011

The Archean Blake River Group (BRG) of Ontario and Quebec is dominated by submarine mafic to intermediate lavas, with more restricted felsic volcanic rocks. Given the good quality of outcrop, and high level of preservation of some BRG rocks, the mafic to intermediate lavas were used in the 1970s and 1980s to better understand the evolution of massive and pillowed submarine flows, and their associated fragmental facies (pillow breccias, hyaloclastite). Potentially, the BRG could also represent a useful volcanic succession for the study of explosive submarine eruption products in the ancient record. Before this is possible, however, a regional inventory of the mafic to intermediate volcaniclastic units is needed to clarify their characteristics and origins. In this paper, we compare and contrast volcaniclastic rocks from three areas within the same formation of the northern BRG in Quebec: the Monsabrais area, the Lac Duparquet area, and the D’Alembert tuff area. Close examination reveals pronounced differences in terms of lateral continuity, thickness, grading, bedding, clast shapes, textures, etc. in the volcaniclastic rocks. These differences are interpreted to reflect vastly different emplacement processes, ranging from hyaloclastite generation as a result of self-fragmentation and lava contact with water (dominant in the Monsabrais and Lac Duparquet areas) to aqueous density currents likely fed directly by explosive submarine eruptions (dominant in the D’Alembert tuff).
Maintenance of asymmetric hybridization between Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) via postzygotic barriers and paternal effects
Authors: Álvarez David , Garcia-Vazquez Eva
Published: April 2011

At the southern European edge of Atlantic salmon ( Salmo salar ) distribution, all the hybrids found in nature are the product of crosses between female salmon and male brown trout ( Salmo trutta ). By artificially producing reciprocal crosses between salmon and trout, we demonstrate that unidirectional hybridization observed in nature is the result of postzygotic barriers that produce very high mortality rates (95%) in female trout × male salmon hybrids and not the consequence of prezygotic isolation or behavioural differences between the two species. Mortality of female trout × male salmon hybrids mainly occurs during the last phases of development, and a high percentage of these surviving hybrids showed external deformities that could compromise survival in the wild. Another important finding is the existence of paternal factor in embryo development. Using time to midhatch as an indicator of developmental rate, female salmon × male trout hybrids hatched faster than female trout × male salmon hybrids, with both developing at a rate intermediate to the pure crosses. The early emergence of female salmon × male trout hybrids, which have similar survival to pure salmons, could have fitness repercussions, since early emerging fry have a competitive advantage over later emerging fry.
Environmental and fishing limitations to the rebuilding of the northern Gulf of St. Lawrence cod stock (Gadus morhua)
Authors: Lambert Yvan
Published: April 2011

Time series of life history traits determining the reproductive potential and productivity of Atlantic cod ( Gadus morhua ) in the northern Gulf of St. Lawrence (nGSL) were obtained for the period covering the collapse and failure of the stock to recover. Decreasing trends in these traits were observed under unfavourable oceanographic conditions, with lowest values reached in the early 1990s. These changes had a negative impact on reproductive rate and instantaneous rate (r) of population growth. Estimates of r used as a proxy of stock productivity were negative when the stock collapsed, indicating that the biomass would have decreased even without fishing. Population abundance projections for the recent period suggest a potential increase in population size of 7.3% per year, with a doubling time of 10.5 years in the absence of exploitation and a near 0% rate with current fishing mortality, indicating that present harvesting does not allow any rebuilding of the stock. Given the similarities in environmental conditions and key life history traits, the situation in the nGSL might reflect the state of many northwest Atlantic cod stocks.
Environmental and maternal effects on embryonic and larval developmental time until dispersal of lake sturgeon (Acipenser fulvescens)
Authors: Duong Thuy Yen , Scribner Kim T. , Crossman James A. , Forsythe Patrick S. , Baker Edward A.
Published: April 2011

For migratory fish like lake sturgeon ( Acipenser fulvescens ), the period from egg deposition through embryonic and larval development until dispersal (ELDTUD) contributes substantially to variation in survival at the individual level and to population levels of recruitment. Using genetically determined parentage, we examined the relative importance of environmental variables in a stream environment (e.g., temperature and discharge) and maternal effects (including individual female body size, spawning time, and location) to ELDTUD on an individual basis. Adult lake sturgeon (n = 208) spawning in the Upper Black River (Michigan, USA), and larvae (n = 1444) dispersing downstream were captured during the 2007 spawning season. We used generalized mixed models and multimodel inference based on Kullback–Leibler information-theoretic criteria to demonstrate that environmental variables and the maternal effects of individual female and spawning time were both important predictors of ELDTUD. Decreasing ELDTUD during the season resulted from linearly increasing temperature and nonlinearly decreasing river discharge. Spawning time and individual female explained a large proportion of variation in ELDTUD. The individual-based approach used in this study provided precise estimates of ELDTUD and also facilitated the partitioning of variation in ELDTUD of larvae produced by the same female and among females spawning at different times and different environmental conditions.
Water chemistry and dissolved organic carbon trends in lakes from Canada’s Atlantic Provinces: no recovery from acidification measured after 25 years of lake monitoring
Authors: Clair Thomas A. , Dennis Ian F. , Vet Robert
Published: April 2011

We analyzed chemistry trends for 66 Atlantic Canada lakes using data collected from 1983 to 2007, as well as from 1990 to 2007 and 2000 to 2007 for the original 66 and a further 25 lakes that were later added to the network. Though receiving the lowest acid deposition in eastern North America, the region’s waters are seriously affected by acid rain because of poorly buffering soils and bedrock. Earlier work had shown that despite large decreases in sulfate deposition, lake pH and calculated acid neutralization capacity (ANCc) had not increased as they had elsewhere in North America and Europe. Despite a 50% decrease in acid deposition, a further 10 years of lake chemistry data showed a regional increase in ANCc only at the beginning of the sampling period but no increase since the early 1990s. There were also no increases in pH and base cations in the region’s lakes. We show a regional increase in Gran titration ANC (ANCG) from 2000 to the present, which we ascribe to increases in dissolved organic carbon that is probably due to a regional increase in annual air temperatures.
EXPORT SUBSIDIES AND THE FIRST-MOVER (DIS)ADVANTAGE
Authors: PIRACHA MATLOOB
Published: April 2011

In the presence of home firm's ability to make a cost-reducing investment before or after the government set its subsidy level, this paper analyzes the impact of timing on the optimal policy of the government. We find that under complete information assumption, the firm will overinvest and consequently, the government will over-subsidize, resulting in lower welfare levels than would arise under non-intervention. We extend the model to the case in which the home firm has private information about its own costs, which it may want to signal to the government through its investment choice. We find that under this setup, the low-cost firm overinvests even more than under full information case, making the policy of non-intervention even more attractive.
IN SEARCH OF A STABLE NARROW MONEY-DEMAND FUNCTION FOR INDONESIA, 1970–2007
Authors: HOSSAIN AKHAND AKHTAR
Published: April 2011

This paper adopts the Johansen approach to cointegration to estimate a narrow money-demand function for Indonesia with annual data for the period 1970–2007. Empirical results suggest that there exists a cointegral relationship between real narrow balances, real permanent income and the deposit rate of interest. The recursive and rolling regression results suggest that the narrow money-demand function has remained largely stable irrespective of ongoing financial reforms in Indonesia since the late 1980s and/or financial crises in the late 1990s. The Quandt-Andrews breakpoint and the Hansen-Johansen stability tests results however suggest that the narrow money-demand relationship had a structural break in the early 1990s. This corresponds to a period of time when the banking and financial reforms in Indonesia took effect. The Chow breakpoint test results suggest that there was also a structural break in the money-demand relationship during the financial crises of the late 1990s.
THE LINKAGE BETWEEN EXPORT AND INCOME: FURTHER EVIDENCE FROM BANGLADESH
Authors: SALIM RUHUL A. , HOSSAIN MOHAMMAD A.
Published: April 2011

This article empirically re-examines the export-led growth hypothesis in the context of Bangladesh using the quarterly data from 1973:1 to 2005:4. The standard time series econometric techniques, such as cointegration and Granger causality tests within the error correction modelling (ECM) are used for this purpose. The results from cointegration analysis suggest that there is stable long-run relationship between exports and income and the results from Granger causality test based on the ECM shows unidirectional causal relationship between exports and income. Thus, these results validate the country's export expansion programs to achieve long-run income growth.
ESTIMATING QUARTERLY GDP DATA FOR THE SOUTH PACIFIC ISLAND NATIONS
Authors: LAHARI WILLIE , HAUG ALFRED A. , GARCES-OZANNE ARLENE
Published: April 2011

Time series analyses generally rely on having a relatively high frequency of consistent and reliable data to work with. However for many South Pacific Island Nations (SPINs), data on macroeconomic series, like GDP, are typically available only annually from the 1980s onwards. This paper empirically estimates quarterly GDP data from annual series using the modified Chow and Lin (1971) approach. We link available annual GDP series for select SPINs with GDP-related series that are available quarterly. We deem that our quarterly estimates of GDP are more consistent and reliable compared to estimates obtained through less sophisticated methods of univariate interpolation.
INVESTIGATION OF STRUCTURAL PHASE TRANSFORMATION IN HALF METALLIC FERROMAGNETIC EuN UNDER PRESSURE
Authors: SRIVASTAVA VIPUL , RAJAGOPALAN M. , SANYAL SANKAR P.
Published: April 2011

The results of first principles calculations of the electronic band structures, density of states, band gap, equilibrium lattice constants, cohesive energies, bulk moduli and magnetic moments are presented for the EuN with rock salt as ambient structure and cesium chloride as high-pressure structure. The tight-binding linear muffin tin orbital method within the local-density approximation is used. Both spin-polarized and non-spin polarized calculations are performed. The magnetic and structural stabilities are determined from the total energy calculations for both nonmagnetic (NM) and ferro-magnetic (FM) states. From the present study EuN illustrates half-metallic. The FM phase is more stable than NM phase. We further predict EuN undergoes a transition from NaCl -type (B1) to CsCl -type structure (B2) at 14.6 GPa, which could not be compared owing to the need of experimental and theoretical results. Futhermore, the bulk moduli, first-order pressure derivatives and magnetic moments are also estimated in B1 and B2 phases. The magnetic moment is estimated to be nearly 6 μB, which is in good agreement with the others reported value. A small decrease in magnetic moment is observed under pressure.
NONMONOTONIC BEHAVIOR OF ELECTRONIC TRANSPORT COEFFICIENTS IN Si–Ge QUANTUM WELLS
Authors: TRIPATHI M. N. , BHANDARI C. M.
Published: April 2011

Quasi-two-dimensional structures are characterized by multiple sub-bands and depending upon the well width and electron density, several sub-bands may be occupied. With an increase in well width more sub-bands are pushed below the Fermi level leading to a possible nonmonotonic variation in transport coefficients. This paper investigates Seebeck coefficient and Lorenz factor in Si 0.9 Ge 0.1 quantum wells taking into account the multiple sub-band contributions.
INFLUENCES OF THE TEMPERATURE AND THE PHONONS EFFECT ON THE PROPERTIES OF THE STRONG-COUPLING EXCITON IN A QUANTUM WELL
Authors: EERDUNCHAOLU  , ZHANG YING , LI HAIFENG , HAN CHAO
Published: April 2011

The influences of the temperature and the phonons effect on the properties of the exciton, which is strongly coupled with interface optical (IO) phonons and weakly coupled with bulk longitudinal-optical (LO) phonons, in a quantum well are studied by means of Huybrechts' linear-combination operator and the Lee–Low–Pines variational method. The expressions for the induced potential of the ground state, the energy shift of the ground state, and the first internal excited state of the exciton were derived. Numerical results are illustrated for AgBr / AgCl quantum well. The results indicate that the induced potential of the ground state, the energy shift of the ground state, and the energy shift of the first internal excited state of the exciton produced by the exciton strongly coupling with IO phonons increase with increasing temperature; however, the induced potential of the ground state, the energy shift of ground state, and the energy shift of the first internal excited state of the exciton produced by the exciton weakly coupling with bulk LO phonons decrease with increasing temperature. The influence of temperature is greater to the changes of the induced potential and the energy shift of the exciton with well widths and the distances between electron and hole.
LONG-RANGE ELECTRON HOPPING AND FERROMAGNETISM IN CLUSTERS
Authors: LIU GUANG-HUA , WANG HAI-LONG , TIAN GUANG-SHAN
Published: April 2011

In the present paper, we investigate the frustration effect caused by the long-range electron hopping on ferromagnetism in atomic or molecular clusters. First, for an idealized Hubbard model with constant electron hopping amplitude, we prove rigorously that interplay between such frustration effect and the on-site Coulomb interaction produces the saturated ferromagnetism when the cluster is slightly doped with electron. Then, by exact diagonalization calculation, we study some more realistic clusters and show that the ferromagnetic ground state is still stable as long as the Coulomb repulsion interaction between electrons is sufficiently strong.
SOLITON ON THE SEMI-INFINITE BAND GAP OF BEC IN AN OPTICAL LATTICE
Authors: WANG D. L. , YAN X. H.
Published: April 2011

By developing a multiple-scale method, we study analytically the dynamics of the soliton inside the semi-infinite band gap (SIBG) of quasi-one-dimensional Bose–Einstein condensates trapped in an optical lattice. In the linear case, a stable condition of soliton formation is obtained. For a weak nonlinearity, whether there occurs a spatially propagating or localized gap soliton is determined by the lattice depth. Meanwhile, we predict the existence of the dark (bright) gap solitons for the repulsive (attractive) interactions in the SIBG, different from that of the gap solitons in other energy gaps. And the collision of two dark (or bright) solitons is nearly elastic under a safe range of atomic numbers. An experimental protocol is further designed for observing these phenomena.
EFFECTIVE MEAN-FIELD THEORY BASED ON CUMULANT EXPANSION IN TREATING CLASSICAL HEISENBERG MODEL ON STACKED TRIANGULAR LATTICE
Authors: YANG LIMIN , ZHAO SONGQING , ZHAO KUN , FAN YUNXIA , LI P. , SONG Y.
Published: April 2011

An effective mean-field theory based on cumulant expansion was used to deal with antiferromagnetic Heisenberg model on planar triangular lattice. The corrections of expansion were performed to the third order. By using the equation of the mean field condition, curves of internal energy E specific heat C staggered helicity K (order parameter) and the variational ratio of staggered helicity X were obtained when the proper values of effective external field were achieved. The calculated results showed that there were two phases (which were ordered antiferromagnetic phase and the disordered phase) in the spin system. The first order critical point is -kTc/Js = 1.65, the second is -kTc/Js = 1.35 and the third is -kTc/Js = 1.29, obviously closer to that of Monte Carlo simulation order by order. And also, the analytic expansion curves derived from this method exhibited higher proximity order by order to the Monte Carlo simulation. Such results showed that this method was a useful tool to obtain thermodynamically observables of spin system.
AUTOMATING A DESIGN METHODOLOGY FOR REUSABLE BUSINESS PROCESS COMPONENTS THROUGH A GENETIC ALGORITHM
Authors: RUNGWORAWUT WARARAT , SENIVONGSE TWITTIE
Published: April 2011

A Business Process Model (BPM) describes a large system of activities that altogether perform a business function. As a particular business function may be required among business processes of the same or different business domains, its corresponding BPM can be reused. Adopting an existing principle of business component fabrication, this paper discusses a methodology for fabricating reusable business process components. The methodology follows the proposed Business Process Component Design (BupCod) model which, based on the BPM of a business, derives business process components by decomposing the BPM into smaller partitions for use in modeling other business processes. The partitioning into business process components is based on five characteristics of component structure (i.e. inter-component coupling, intra-component cohesion, number of components, component size, and complexity) and considers five managerial goals in component fabrication (i.e. cost effectiveness, ease of assembly, customization, reusability, and maintainability). A genetic algorithm is used to automate the design and recommend to a business process component designer the partitioning that optimally achieves the required managerial goals. A design example is given through the process of opening an Internet trading account with a financial securities company in Thailand. The evaluation of the methodology and its automation, based on experiments and feedback from the industry, obtains positive results.
PERISTALTIC TRANSPORT OF A MAXWELL FLUID IN A CHANNEL OF VARYING CROSS SECTION INDUCED BY ASYMMETRIC WAVES: APPLICATION TO EMBRYO TRANSPORT WITHIN UTERINE CAVITY
Authors: PANDEY S. K. , CHAUBE M. K.
Published: April 2011

This is an attempt to analyze the peristaltic flow of a Maxwell fluid in a tapered channel. Peristaltic wave trains with different amplitudes and phases are considered to propagate along the two walls of the channel producing asymmetric wall movements. A perturbation technique is employed to solve the problem by giving due consideration to the non-linear convective acceleration terms in the analysis. The effects of the non-Newtonian parameters relaxation time, angle of inclination between channel walls, and phase difference on the mean flow velocity are analyzed. It is found that the mean axial velocity decreases with relaxation time, phase difference, and the angle between the channel walls. Moreover, the value of the mean axial velocity is found to be less with asymmetric waves as compared with symmetric waves.