bluuebunny/crossref_metadata_2025 huggingface dataset:
“Keeping Young Minds Sharp”: Children's Cognitive Stimulation and the Rise of Parenting Magazines, 1959–2003*
Authors: QUIRKE LINDA
Published: July 2010

Dans cet article, l'auteure etudie l'éthos changeant du métier de parent en se fondant sur l'examen des magazines et des articles sur l'art d'être parent. La diversification et l'augmentation substantielle du nombre de magazines sur l'éducation des enfants dans quatre pays industrialisés d'expression anglaise démontrent une grande préoccupation par rapport à l'« art d'etre parent » en tant qu'entreprise intentionnelle. Une analyse de contenu de plus de 500 articles canadiens sur le sujet révèle un déplacement de l'importance placée sur les activités d'« amusement » vers un intérêt croissant pour l'education et le développement cognitif des enfants. En accord avec ceux et celles qui observent au fil du temps un souci accru concernant le développement cognitif des enfants, l'auteure pense que les parents canadiens sont de plus en plus encouragés à favoriser activement les aptitudes aux études de leurs enfants.

This study is an exploration of the changing ethos of parenting based on an examination of parenting magazines and articles. The substantial growth and diversification of parenting magazines in four English‐speaking industrialized countries indicate a larger preoccupation about “parenting” as a deliberate undertaking. A content analysis of more than 500 Canadian parenting articles reveals a shift in emphasis from “fun” activities to an increasing focus on schooling and children's cognitive development. Consistent with others who document a heightened concern for children's cognitive development over time, I find that Canadian parents are increasingly encouraged to actively foster their children's academic skills.
Interrogating Racialized Global Labour Supply: An Exploration of the Racial/National Replaceme of Foreign Agricultural Workers in Canada*
Authors: Preibisch Kerry , Binford Leigh
Published: July 2010

Dans cet article, on analyse le remplacement des travailleurs antillais par des Mexicains dans le Programme des travailleurs agricoles saisonniers du gouvernement du Canada, en mettant l'accent sur le rôle des interprétations racialisées dans la mise en œuvre de ce genre de programme. On y soutient qu'un mécanisme de racialisation étaie les discours des agriculteurs ontariens à la recherche de la main‐d œuvre la plus laborieuse, fiable et flexible. Parfois même, les discours des agriculteurs affichent un racisme grossier, dépeignant les honimes antillais comme des Noirs hypersexués qui présentent un risque pour les Canadiennes, alors que, d'autres fois, ces préjugés raciaux sont formulées en termes de prédispositions physiques ou psychologiques à travailler à certaines récoltes.

This paper analyses the replacement of Caribbean workers by Mexicans in Canada's Seasonal Agricultural Workers Program, highlighting the role of racialized understandings in implementing foreign worker programs. It argues that a process of racialization underpins the discourses employed by Ontario growers in search of the most hardworking, reliable and flexible labour force. Sometimes grower discourses manifest a crude racism, casting Caribbean men as hypersexualized Black subjects who pose a risk to Canadian women, while other times these racialized assumptions are framed in terms of physical and/or psychic dispositions to the production of certain crops.
Earnings of Chinese Immigrants in the Enclave and Mainstream Economy*
Authors: Li Peter S. , Dong Chunhong
Published: July 2010

La documentation sur le sujet n'est pas décisive quant à savoir si léconomie ethnique enclavée enregistre un rendement économique comparable chez les travailleurs et les entrepreneurs immigrants à ceux qui se situent dans le courant économique principal. Les auteurs de cette étude utilisent des données du Recensement du Canada de 2001 sur la langue la plus utilisée au travail din de mesurer la participation des immigrants chinois à léconomie enclavée. Après les avoir comparés au capital humain ainsi qu'aux variations liées au travail et au milieu urbain, les résultats démontrent que le rendement est moins élevé chez les hommes et chez les femmes de l'enclave que celui des gens qui se trouvent dans le courant économique principal. Les caractéristiques de la langue et le type de travail qui s'effectue dans léconomie enclavée expliquent pourquoi le rendement y est inférieur à celui obtenu dans le courant économique principal.

The literature in inconclusive as to whether the immigrant enclave economy offers returns to immigrant workers and entrepreneurs comparative to those in the mainstream economy. This study uses data from the 2001 Census of Canada on language most often used at work to measure enclave economy participation for Chinese immigrants. The findings show that returns are lower for men or women in the enclave than those in the mainstream economy, respectively, after controlling for human capital, work‐related and urban variations. Language features of and job type in the enclave economy explain why returns are inferior to that of the mainstream economy.
Who the Heck Is Don Bradman? Sport Culture and Social Class in British Columbia, Canada*
Authors: Veenstra Gerry
Published: July 2010

Les classes sociales et la culture sportive canadienne sont‐elles interreliées ? L'auteur, inspiré par les cadres conceptuels de classes sociales de Pierre Bourdieu et d'Erik Wright, dErit les résultats d'un travail exploratoire sur les classes sociales et le sport dans la province de Colombie‐Britannique. Son analyse utilise des données d'enquête originales afin de déterminer l'importance qu'ont les caractéristiques démographiques (sexe, âge et naissance), le capital (économique, culture1 et social) et les indicateurs néomarxistes des catégories sociales (comme la propriétééconomique, le contrôle sur le lieu de travail et les compétences professionnelles) sur l'étendue des connaissances sportives et sur la participation aux activités sportives. Cette analyse constitue donc un petit pas vers l'identification des classes sociales au Canada, soutenue ou délimitée par l'exercice des choix et des pratiques culturelles.

Are social class and Canadian sports culture entwined? This article, inspired by the social class frameworks of Pierre Bourdieu and Erik Wright, describes results from an exploratory investigation of class and sport in the province of British Columbia. The analysis utilizes original survey data to determine the degree to which demographic characteristics (gender, age and nativity), capitals (economic, cultural and social) and neo‐Marxist indicators of class position (such as economic ownership, control in the workplace and job skill) predict breadth of sports knowledge and participation in sporting activities. The analysis therefore represents a small step towards identifying social classes in Canada that are sustained or delimited by the wielding of cultural tastes and practices.
Les Chinois de Paris et de Montréal: analyse comparative de deux communautés en situation d'immigration*
Authors: Nicholls Natalie C.
Published: July 2010

This article is a comparative study of two Chinese communities in two countries that differ in their history and their political direction when it comes to immigration: Canada and France. Although it neither concludes their independence nor the disappearance of the role of national states, the article points out many similarities in the structure, organization and internal economy relying on cross‐border ethnic networks.

Le présent article consiste en une étude comparative de deux communautés chinoises en situation d'immigration dans deux pays différant par leur histoire et leur orientation politique: le Canada et la France. Bien qu'il n'en conclue ni à l'indépendance de ces communautés ni à la disparition du rôle des États nationaux, l'article relève maintee ressemblances sur le plan de la structure, de l'organisation et de l'économie interne reposant sur des réseaux ethniques transcendant les frontières.
Sternoclavicular Joint Arthritis: Unrecognized Cause of Shoulder Impingement
Authors: Taranu Razvan , Feary Joy , Dufosse Julian W. B. , Bayliss Neil C.
Published: July 2010

Background

We wish to demonstrate that osteoarthritis of the sternoclavicular joint can be a cause of tertiary subacromial impingement as a result of decreased motion of the clavicle.

Materials

We present a series of five patients with tertiary subacromial impingement caused by stiffness of the sternoclavicular joint. All five patients attended our upper limb clinic with what appeared to be subacromial impingement. Close examination revealed that they had an inability to shrug the affected shoulder as a result of reduced mobility of the sternoclavicular joint caused by osteoarthritis. None of the patients had symptoms localized to the sternoclavicular joint itself. After appropriate investigation, four patients underwent excision of the medial end of the clavicle and one responded well to physiotherapy.

Results

All patients regained full shoulder movements and resolution of the subacromial impingement pain.

Discussion

We recommend that the ‘shrug test’ should be part of routine shoulder examination so that sternoclavicular joint pathology can be recognized at an early stage and acted on appropriately. We conclude that subacromial impingement can be caused by impaired clavicle rotation as a result of osteoarthritic changes in the sternoclavicular joint.
How I Perform Resurfacing Shoulder Replacement
Authors: Copeland Stephen A. , Sforza Giuseppe
Published: July 2010

Surface replacement arthroplasty of the shoulder is a well accepted and frequently performed procedure. There are reports of good long-term results to support this. As with all surgical procedures, however, the results depend on a thorough understanding of the surgical technique. This article discusses the most common pitfalls and suggests solutions developed over 25 years of use.
Early Acromial Erosion with the Synthes Hook Plate: An Unusual Complication and Its Treatment
Authors: Odak Saurabh , Burton David
Published: July 2010

We report an unusual case of early erosion of acromion with a Hook-plate used for fixation of lateral clavicle fracture. The management options and treatment is discussed further.
Experimental Physiology –Research Paper: The effect of cooling on the contractility of equine digital small lamellar arteries: modulating role of the endothelium
Authors: Zerpa Hector , Berhane Yoel , Elliott Jonathan , Bailey Simon R.
Published: July 2010

The equine hoof displays thermoregulatory functions, and the blood vessels lying under the hoof wall are temperature sensitive. The aim of this study was to investigate the effect of cooling on the contractile responses to α‐adrenoceptor and 5‐HT receptor stimulation in equine small lamellar arteries using wire myography. The role of the endothelium in the response mediated by 5‐HT was also evaluated. Moderate cooling caused a reduction of the contraction induced by depolarizing Krebs solution (DKS, containing 118 mmKCl) and the maximal contraction caused by UK‐14304 (α2‐adrenoceptor agonist). The potency of methoxamine (α1‐adrenoceptor agonist) was reduced by cooling [pD2(−log EC50) at 22°C, 5.7 (5.5–6.0)versus30°C, 5.9 (5.7–6.1)]; however, the efficacy was maintained. The contractions evoked by sumatripan and α‐methyl 5‐HT (5‐HT receptor agonists) were not modified by moderate cooling. In contrast, a cooling‐enhanced contraction was observed in response to 5‐HT [maximum response (Emax) at 22°C, 213.2 ± 13% DKSversus30°C, 179.9 ± 11% DKS]. Furthermore, this effect was more evident in endothelium‐denuded lamellar arteries (Emaxat 22°C, 270.2 ± 26% DKSversus30°C, 172.2 ± 20% DKS), suggesting a potential modulating role of the endothelium. Thel‐NAME/ibuprofen‐resistant relaxation in response to carbachol was reduced by cooling in small lamellar arteries precontracted with 5‐HT but not phenylephrine. Therefore, a moderate reduction of temperature modulates the reactivity of small lamellar arteries by enhancing the 5‐HT‐mediated contraction, but inhibits the α‐adrenoceptor‐mediated response. Furthermore, the endothelium of these blood vessels may play an important role in preventing excessive vasoconstriction in response to 5‐HT and maintaining digital blood flow in cool environmental temperatures.
PIV Study of Laminar Wall Jets of Non-Newtonian Fluids
Authors: Adane K. F. K. , Tachie M. F.
Published: July 2010

Three-dimensional laminar wall jet flows of shear-thinning non-Newtonian fluids have been studied using a particle image velocimetry technique. The non-Newtonian fluids were prepared from xanthan gum solutions of various concentrations. The velocity measurements were performed in various streamwise-transverse and streamwise-spanwise planes at various inlet Reynolds numbers. From these measurements, the maximum velocity decay, jet half-widths, and velocity profiles were obtained to study the effects of Reynolds number and fluid type on the characteristics of the wall jet flows. It was observed that the maximum velocity decay and jet half-widths depend on inlet Reynolds number and fluid but the similarity velocities profiles are independent of both Reynolds number and specific fluid type.
Effect of J-Groove on the Suppression of Swirl Flow in a Conical Diffuser
Authors: Kurokawa Junichi , Imamura Hiroshi , Choi Young-Do
Published: July 2010

The purpose of this study is to examine the validity of J-grooves in controlling and suppressing the swirl flow in a conical diffuser, for draft surge suppression in a Francis turbine, which is caused by the swirl flow from the runner outlet into the draft tube. “J-groove” composed of shallow grooves and mounted parallel to the pressure gradient on the diffuser wall is a very simple passive device to suppress several abnormal phenomena in turbomachinery. The experimental study has been performed using the conical diffuser with a divergent angle of 20 deg. The measured results of the velocity distribution in the diffuser show that a considerable reduction in the swirl intensity is attained by using J-grooves. Besides, the amplitude of pressure fluctuation caused by the rotation of the vortex core around the dead water region near the diffuser inlet is reduced by J-grooves.
Modeling the Unsteady Cavitating Flow in a Cross-Flow Water Turbine
Authors: Sansone E. , Pellone C. , Maitre T.
Published: July 2010

The noncavitating and cavitating flows over a cross-flow water turbine are simulated by using an unsteady Navier–Stokes formulation. For the cavitating flow case, a homogeneous mixture with a varying density is considered and one additional transport equation is explicitly solved in time for the liquid volume fraction. The instantaneous rate of vapor production and absorption appearing as a source term is governed by a hydrodynamic model based on a simplified bubble dynamic equation. The spatial discretization is achieved by a 2D multiblock technique consisting of fixed and rotating blocks, which were especially adapted for Darrieus geometry. Several test cases corresponding to experiments performed on fixed and rotating blades are selected to compare the numerical results with experimental data. Finally, a calculation of a monobladed cavitating cross-flow turbine is presented. The effect of cavitation on the dynamic stall phenomenon and on the turbine performance is analyzed. In particular, it is shown that cavitation earlier reveals the stall phenomenon on the blades and magnifies the size of the shedding vortex structures in the turbine.
Pressure Loss in a Horizontal Two-Phase Slug Flow
Authors: Kabiri-Samani A. R. , S. M. Borghei
Published: July 2010

The study of air-water, two-phase flows in hydraulic structures such as pressurized flow tunnels, culverts, sewer pipes, junctions, and similar conduits is of great importance for design purposes. Air can be provided by vortices at water intakes, pumping stations, aerators, steep channels, etc. Under certain conditions, air may also be introduced into pressurized intake systems, which may form large bubbles in portions of the pipe. The bubbles may, in turn, cause an unstable slug flow, or other flow patterns, that leads to sever periodic transient pressure. In this paper, an experimental model (a circular and transparent pipeline, 90 mm in ID and 10 m in length) is used to predict pressure loss in a pipeline or tunnel involving resonance and shock waves introduced by a two-phase air-water slug flow. For this purpose, differential pressure transducers were used to measure pressure loss variations in time along the pipeline at different sections and for different air/water flow rates. The experimental results of pressure loss for different hydraulic and geometric properties indicate that Weber number (We), Froude number (Fr), and air concentration (C) are the most important parameters affecting pressure loss. Finally, relations for forecasting pressure loss in these situations are presented as a function of flow characteristics.
Cultivating Chaos
Pandora's Seed
The Unforeseen Cost of Civilization

by Spencer Wells

Random House, New York, 2010. 251 pp. $26, C$31. ISBN 9781400062157. Allen Lane, London. £20. ISBN 9780713997552.
Authors: Ali Saleem H.
Published: July 2010

Wells considers some of the drawbacks that have stemmed from the prehistoric shift to farming for our food supply.
Pairs Rule Quantum Interference
Authors: Franson James D.
Published: July 2010

Quantum interference between many different pathways is simply the sum of the effects from all pairs of pathways.
Reactivation of Hepatic EPO Synthesis in Mice After PHD Loss
Authors: Minamishima Yoji Andrew , Kaelin William G.
Published: July 2010

Stimulating erythropoietin production in the mouse liver points to a treatment for anemia caused by chronic kidney disease.
Launched at 36,000
g
Authors: van Leeuwen Johan L.
Published: July 2010

Peat mosses project thousands of spores in a turbulent vortex ring from a millimeter-sized pressurized cylindrical capsule.
Seeing the Light of Day
Authors: Cepko Constance
Published: July 2010

A potential gene therapy approach could restore some vision to patients with retinitis pigmentosa.
Escalating Threat of Wheat Rusts
Authors: Hovmøller Mogens Støvring , Walter Stephanie , Justesen Annemarie Fejer
Published: July 2010

Last month, nearly 600 scientists from more than 80 countries convened in St. Petersburg, Russia, at the International Wheat Conference to discuss the world's most widely planted crop. This came on the heels of a Borlaug Global Rust Initiative (BGRI) workshop that focused on the rapidly spreading fungal diseases known as wheat rusts, which are causing epidemics that require urgent action. If we are to prevent devastating crop losses, nations must coordinate to enact short-term solutions; they must also expand long-term efforts in research, plant breeding, and surveillance.
Nobelist Paul Nurse to Pilot Royal Society, London Superlab
Authors: Kaiser Jocelyn
Published: July 2010

Paul Nurse spoke with
Science
last week about his past, his recent suggestion to bolster U.K. funding for 100 to 150 top researchers, and his busy future as both president of the Royal Society and founding director of the UK Centre for Medical Research and Innovation.
A Craving for Hydropower
Authors: Vince Gaia
Published: July 2010

Environmentalists and independent energy analysts argue that by improving efficiency and investing in renewable energy, Chile could find more than enough power within its borders for at least a decade—and without more dams. So far, however, energy planners have not been persuaded.
Flexible Label-Free Quantitative Assay for Antibodies to Influenza Virus Hemagglutinins
Authors: Carney Paul J. , Lipatov Aleksandr S. , Monto Arnold S. , Donis Ruben O. , Stevens James
Published: July 2010

During the initial pandemic influenza H1N1 virus outbreak, assays such as hemagglutination inhibition and microneutralization provided important information on the relative protection afforded by the population's cross-reactivity from prior infections and immunizations with seasonal vaccines. However, these assays continue to be limited in that they are difficult to automate for high throughput, such as in pandemic situations, as well as to standardize between labs. Thus, new technologies are being sought to improve standardization, reliability, and throughput by using chemically defined reagents rather than whole cells and virions. We now report the use of a cell-free and label-free flu antibody biosensor assay (f-AbBA) for influenza research and diagnostics that utilizes recombinant hemagglutinin (HA) in conjunction with label-free biolayer interferometry technology to measure biomolecular interactions between the HA and specific anti-HA antibodies or sialylated ligands. We evaluated f-AbBA to determine anti-HA antibody binding activity in serum or plasma to assess vaccine-induced humoral responses. This assay can reveal the impact of antigenic difference on antibody binding to HA and also measure binding to different subtypes of HA. We also show that the biosensor assay can measure the ability of HA to bind a model sialylated receptor-like ligand. f-AbBA could be used in global surveillance laboratories since preliminary tests on desiccated HA probes showed no loss of activity after >2 months in storage at room temperature, indicating that the same reagent lots could be used in different laboratories to minimize interlaboratory assay fluctuation. Future development of such reagents and similar technologies may offer a robust platform for future influenza surveillance activities.
Diagnosis of Canine Vector-Borne Diseases in Young Dogs: a Longitudinal Study
Authors: Otranto Domenico , Testini Gabriella , Dantas-Torres Filipe , Latrofa Maria S. , Diniz Pedro Paulo Vissotto de Paiva , de Caprariis Donato , Lia Riccardo P. , Mencke Norbert , Stanneck Dorothee , Capelli Gioia , Breitschwerdt Edward B.
Published: July 2010

Canine vector-borne diseases (CVBDs) pose a diagnostic challenge, particularly when a dog is coinfected with more than one pathogen. The purpose of this study was to generate information about the diagnosis of CVBDs in young dogs following their first exposure to flea, tick, sand fly, louse, and mosquito vectors. From March 2008 to May 2009, 10 purpose-bred young naive beagle dogs and a cohort of 48 mixed-breed dogs living in an area to which CVBD is endemic in southern Italy were monitored using different diagnostic tests (cytology, serology, and PCR). Overall, PCR detected the highest number of dogs infected with
Anaplasma platys
,
Babesia vogeli
, and
Ehrlichia canis
, whereas seroconversion was a more sensitive indicator of exposure to
Leishmania infantum
. For
A
.
platys
infection, combining blood and buffy coat cytology in parallel enhanced the relative sensitivity (SE
rel
) (87.3%). For
B
.
vogeli
, the best diagnostic combination was buffy coat cytology and serology used in parallel (SE
rel
, 67.5%), whereas serology and PCR used in parallel (SE
rel
, 100%) was the best combination for
L
.
infantum
. Overall, 12 (20.7%) dogs were coinfected; however, the percentage of new coinfections decreased from baseline (50%) to the first (33.3%) and second (16.6%) follow-up time points. Numbers of coinfections with
A
.
platys
and
B
.
vogeli
were significantly higher (
P
< 0.05) than coinfections with other pathogen combinations. The data generated in this study provide insights on the incidence of certain pathogens infecting young dogs in southern Italy, highlight important diagnostic testing limitations, and support the use of multiple diagnostic modalities when attempting to confirm a tick-borne infection in an individual dog or in a canine population.
Aerococcus urinae
: Severe and Fatal Bloodstream Infections and Endocarditis
Authors: de Jong Margriet F. C. , Soetekouw Robin , ten Kate Reinier W. , Veenendaal Dick
Published: July 2010

Aerococcus urinae
is a pathogen that rarely causes severe or fatal infections. We describe four cases of severe
A. urinae
bloodstream infections. All patients had underlying urologic conditions. Urine cultures, however, were negative.
Disseminated Mycosis in Veiled Chameleons (
Chamaeleo calyptratus
) Caused by
Chamaeleomyces granulomatis
, a New Fungus Related to
Paecilomyces viridis
Authors: Sigler Lynne , Gibas Connie Fe C. , Kokotovic Branko , Bertelsen Mads F.
Published: July 2010

An outbreak of disseminated granulomatous disease occurred in a group of veiled chameleons (
Chamaeleo calyptratus
) in a zoo collection. An adult female and six offspring developed large granulomas in multiple organs and were euthanized. At necropsy, roughly spherical yellow-to-white nodules 1 to 3 mm in diameter were grossly visible in the liver and other organs. Histopathology revealed fungal elements that were spherical to ovoid in shape, fragments of slender to irregularly swollen hyphae, and occasional conidia produced on phialides. Fungal isolates were initially suspected on the basis of morphology results to represent
Paecilomyces viridis
, a species known only from one outbreak of fatal mycosis in carpet chameleons (
Furcifer lateralis
). Data obtained from morphological studies and from phylogenetic analyses of nuclear ribosomal rRNA (rDNA) sequence data revealed the Danish chameleon isolates to be a related undescribed anamorphic species within the family Clavicipitaceae that includes many insect pathogens.
Chamaeleomyces granulomatis
gen. et sp. nov. is given as the name for the newly described fungus, and
P. viridis
is transferred to the new genus as
Chamaeleomyces viridis
comb. nov.
Chamaeleomyces
species are distinguished by having basally swollen phialides tapering to a narrow neck, conidia in fragile chains, and pale green to greenish-gray colonies. Both species are dimorphic, producing a transitory yeast stage characterized by ovoid-to-subglobose or subcylindrical yeast-like cells.
Chamaeleomyces
species appear to be rare but aggressive pathogens of chameleons.
Characterization of Some Bacterial Strains Isolated from Animal Clinical Materials and Identified as
Corynebacterium xerosis
by Molecular Biological Techniques
Authors: Palacios Lucía , Vela Ana Isabel , Molin Kent , Fernández Ana , Latre Maria Victoria , Chacón Gema , Falsen Enevold , Fernández-Garayzábal José Francisco
Published: July 2010

Eighteen
Corynebacterium xerosis
strains isolated from different animal clinical specimens were subjected to phenotypic and molecular genetic studies. On the basis of the results of the biochemical characterization, the strains were tentatively identified as
C. xerosis
. Phylogenetic analysis based on comparative analysis of the sequences of 16S rRNA and
rpoB
genes revealed that the 18 strains were highly related to
C. xerosis
,
C. amycolatum
,
C. freneyi
, and
C. hansenii
. There was a good concordance between 16S rRNA and partial
rpoB
gene sequencing results, although partial
rpoB
gene sequencing allowed better differentiation of
C. xerosis
. Alternatively,
C. xerosis
was also differentiated from
C. freneyi
and
C. amycolatum
by restriction fragment length polymorphism analysis of the 16S-23S rRNA gene intergenic spacer region. Phenotypic characterization indicated that besides acid production from
d
-turanose and 5-ketogluconate, 90% of the strains were able to reduce nitrate. The absence of the fatty acids C
14:0
, C
15:0
, C
16:1
ϖ7
c
, and C
17:1
ϖ8
c
can also facilitate the differentiation of
C. xerosis
from closely related species. The results of the present investigation demonstrated that for reliable identification of
C. xerosis
strains from clinical samples, a combination of phenotypic and molecular-biology-based identification techniques is necessary.
Additive Contribution of HLA Class I Alleles in the Immune Control of HIV-1 Infection
Authors: Leslie Alasdair , Matthews Philippa C. , Listgarten Jennifer , Carlson Jonathan M. , Kadie Carl , Ndung'u Thumbi , Brander Christian , Coovadia Hoosen , Walker Bruce D. , Heckerman David , Goulder Philip J. R.
Published: July 2010

Previous studies have identified a central role for HLA-B alleles in influencing control of HIV infection. An alternative possibility is that a small number of HLA-B alleles may have a very strong impact on HIV disease outcome, dominating the contribution of other HLA alleles. Here, we find that even following the exclusion of subjects expressing any of the HLA-B class I alleles (B*57, B*58, and B*18) identified to have the strongest influence on control, the dominant impact of HLA-B alleles on virus set point and absolute CD4 count variation remains significant. However, we also find that the influence of HLA on HIV control in this C-clade-infected cohort from South Africa extends beyond HLA-B as HLA-Cw type remains a significant predictor of virus and CD4 count following exclusion of the strongest HLA-B associations. Furthermore, there is evidence of interdependent protective effects of the HLA-Cw*0401-B*8101, HLA-Cw*1203-B*3910, and HLA-A*7401-B*5703 haplotypes that cannot be explained solely by linkage to a protective HLA-B allele. Analysis of individuals expressing both protective and detrimental alleles shows that even the strongest HLA alleles appear to have an additive rather than dominant effect on HIV control at the individual level. Finally, weak but significant frequency-dependent effects in this cohort can be detected only by looking at an individual's combined HLA allele frequencies. Taken together, these data suggest that although individual HLA alleles, particularly HLA-B, can have a strong impact, HIV control overall is likely to be influenced by the additive effect of some or all of the other HLA alleles present.
The Effect of Clade-Specific Sequence Polymorphisms on HIV-1 Protease Activity and Inhibitor Resistance Pathways
Authors: Bandaranayake Rajintha M. , Kolli Madhavi , King Nancy M. , Nalivaika Ellen A. , Heroux Annie , Kakizawa Junko , Sugiura Wataru , Schiffer Celia A.
Published: July 2010

The majority of HIV-1 infections around the world result from non-B clade HIV-1 strains. The CRF01_AE (AE) strain is seen principally in Southeast Asia. AE protease differs by ∼10% in amino acid sequence from clade B protease and carries several naturally occurring polymorphisms that are associated with drug resistance in clade B. AE protease has been observed to develop resistance through a nonactive-site N88S mutation in response to nelfinavir (NFV) therapy, whereas clade B protease develops both the active-site mutation D30N and the nonactive-site mutation N88D. Structural and biochemical studies were carried out with wild-type and NFV-resistant clade B and AE protease variants. The relationship between clade-specific sequence variations and pathways to inhibitor resistance was also assessed. AE protease has a lower catalytic turnover rate than clade B protease, and it also has weaker affinity for both NFV and darunavir (DRV). This weaker affinity may lead to the nonactive-site N88S variant in AE, which exhibits significantly decreased affinity for both NFV and DRV. The D30N/N88D mutations in clade B resulted in a significant loss of affinity for NFV and, to a lesser extent, for DRV. A comparison of crystal structures of AE protease shows significant structural rearrangement in the flap hinge region compared with those of clade B protease and suggests insights into the alternative pathways to NFV resistance. In combination, our studies show that sequence polymorphisms within clades can alter protease activity and inhibitor binding and are capable of altering the pathway to inhibitor resistance.
Interferon Regulatory Factor 3-Dependent Pathways Are Critical for Control of Herpes Simplex Virus Type 1 Central Nervous System Infection
Authors: Menachery Vineet D. , Pasieka Tracy Jo , Leib David A.
Published: July 2010

The initiation of the immune response at the cellular level relies on specific recognition molecules to rapidly signal viral infection via interferon (IFN) regulatory factor 3 (IRF-3)-dependent pathways. The absence of IRF-3 would be expected to render such pathways inoperative and thereby significantly affect viral infection. Unexpectedly, a previous study found no significant change in herpes simplex virus (HSV) pathogenesis in IRF-3
−/−
mice following intravenous HSV type 1 (HSV-1) challenge (K. Honda, H. Yanai, H. Negishi, M. Asagiri, M. Sato, T. Mizutani, N. Shimada, Y. Ohba, A. Takaoka, N. Yoshida, and T. Taniguchi, Nature 434:772-777, 2005). In contrast, the present study demonstrated that IRF-3
−/−
mice are significantly more susceptible to HSV infection via the corneal and intracranial routes. Following corneal infection with 2 × 10
6
PFU of HSV-1 strain McKrae, 50% of wild-type mice survived, compared to 10% of IRF-3-deficient mice. Significantly increased viral replication and inflammatory cytokine production were observed in brain tissues of IRF-3
−/−
mice compared to control mice, with a concomitant deficit in production of both IFN-β and IFN-α. These data demonstrate a critical role for IRF-3 in control of central nervous system infection following HSV-1 challenge. Furthermore, this work underscores the necessity to evaluate multiple routes of infection and animal models in order to fully determine the role of host resistance factors in pathogenesis.
Inhibition of Superinfection and the Evolution of Viral Latency
Authors: Berngruber Thomas W. , Weissing Franz J. , Gandon Sylvain
Published: July 2010

Latent viruses generally defend their host cell against superinfection by nonlatent virulent mutants that could destroy the host cell. Superinfection inhibition thus seems to be a prerequisite for the maintenance of viral latency. Yet viral latency can break down when resistance to superinfection inhibition, known as ultravirulence, occurs. To understand the evolution of viral latency, we have developed a model that analyzes the epidemiology of latent infection in the face of ultravirulence. We show that latency can be maintained when superinfection inhibition and resistance against it coevolve in an arms race, which can result in large fluctuations in virulence. An example is the coevolution of the virulence and superinfection repressor protein of phage λ (
cI
) and its binding target, the λ
oLoR
operator. We show that this repressor/operator coevolution is the driving force for the evolution of superinfection immunity groups. Beyond latent phages, we predict analogous dynamics for any latent virus that uses a single repressor for the simultaneous control of virulence and superinfection.
Intrapatient Variation of the Respiratory Syncytial Virus Attachment Protein Gene
Authors: Agoti Charles N. , Mbisa Jean L. , Bett Ann , Medley Graham F. , Nokes D. James , Cane Patricia A.
Published: July 2010

Intrapatient variability of the attachment (G) protein gene of respiratory syncytial virus (RSV) was examined using both population and single-genome sequencing. Samples from three patients infected with a group B virus variant which has a 60-nucleotide duplication in the G protein gene were examined. These samples were chosen because occasional mixed sequence bases were observed. In a minority of RSV genomes from these patients considerable variability was found, including point mutations, insertions, and deletions. Of particular note, the deletion of the exact portion of the gene which had been duplicated in some isolates was observed in viral RNAs from two patients.
An Interaction between the Nucleocapsid Protein and a Component of the Replicase-Transcriptase Complex Is Crucial for the Infectivity of Coronavirus Genomic RNA
Authors: Hurst Kelley R. , Ye Rong , Goebel Scott J. , Jayaraman Priya , Masters Paul S.
Published: July 2010

The coronavirus nucleocapsid (N) protein plays an essential role in virion assembly via interactions with the large, positive-strand RNA viral genome and the carboxy-terminal endodomain of the membrane protein (M). To learn about the functions of N protein domains in the coronavirus mouse hepatitis virus (MHV), we replaced the MHV N gene with its counterpart from the closely related bovine coronavirus (BCoV). The resulting viral mutant was severely defective, even though individual domains of the N protein responsible for N-RNA, N-M, or N-N interactions were completely interchangeable between BCoV and MHV. The lesion in the BCoV N substitution mutant could be compensated for by reverting mutations in the central, serine- and arginine-rich (SR) domain of the N protein. Surprisingly, a second class of reverting mutations were mapped to the amino terminus of a replicase subunit, nonstructural protein 3 (nsp3). A similarly defective MHV N mutant bearing an insertion of the SR region from the severe acute respiratory syndrome coronavirus N protein was rescued by the same two classes of reverting mutations. Our genetic results were corroborated by the demonstration that the expressed amino-terminal segment of nsp3 bound selectively to N protein from infected cells, and this interaction was RNA independent. Moreover, we found a direct correlation between the N-nsp3 interaction and the ability of N protein to stimulate the infectivity of transfected MHV genomic RNA (gRNA). Our results suggest a role for this previously unknown N-nsp3 interaction in the localization of genomic RNA to the replicase complex at an early stage of infection.
Lake Acidification as a Limiting Factor in the Distribution of the Freshwater AmphipodHyalella azteca
Authors: Stephenson M. , Mackie G. L.
Published: July 2010

The distribution of the freshwater amphipod Hyalella azteca in 79 Ontario lakes suggests that its absence may be a good indicator of lake acidification. Hyalella azteca was present in 69 of 71 nonacidified lakes, and absent in 8 of 8 lakes which either are now ar recently were considered acidified. Bioassay data indicate a 96-h LC50of pH 4.4 and a 10-d threshold LC50of pH 4.5 for H. azteca in a natural surface water. Hyalella azteca is extremely rare in Plastic Lake, which undergoes severe short-term acidification in spring, and recruitment is delayed 2 wk in Heeney Lake which undergoes similar short-term acidification, in Dickie, Harp, Red Chalk, and Blue Chalk lakes, where springtime pH depressions below pH 4.7 were not recorded, H. azteca is abundant.
Phosphate Uptake by Microorganisms in Lake Water: Deviations from Simple Michaelis–Menten Kinetics
Authors: Tarapchak Stephen J. , Herche Lynn R.
Published: July 2010

Orthophosphate (31Pi) uptake rates by natural Lake Michigan microbial assemblages were measured to test a hypothesis that the instantaneous velocity of31Piuptake at low added substrate concentrations is higher than predicted by the simple Michaelis–Menten equation. Analysis of data from most experiments verified this prediction:31Piturnover times (Tcalc) obtained by back-extrapolating from "low" substrate regions in Woolf plots ranged from 25% to nearly 3000% of those calculated from "high" substrate regions. Simulation analysis demonstrated that deviations in Tcalccould be at least an order of magnitude higher than previously predicted. Large (>1000%) discrepancies from the simple Michaelis–Menten equation could be caused by "skewed" or "clumped" distributions, where the range in both species half-saturation constants (Kt) and relative abundances is very wide and species with the lowest Ktvalues are most abundant. A comparison of Ktvalues for mixed microbial assemblages in Lake Michigan (0.16–19.4 μg P∙L−1) with those from laboratory culture studies (11–364 μg P∙L−1) demonstrates that natural microbial populations have adapted to P-limited environments by synthesizing uptake systems that have Ktvalues at least an order of magnitude below those detected in culture studies.
Identification of Critical Nutrient Levels through Field Verification of Models for Phosphorus and Phytoplankton Growth
Authors: Auer Martin T. , Kieser Mark S. , Canale Raymond P.
Published: July 2010

Two models for phosphorus and phytoplankton growth were field verified along a marked gradient in trophic conditions in Green Bay (Lake Michigan): one, the Monod model, relates growth rate to external (dissolved) phosphorus concentration, and the other, the Droop model, describes growth rate as a function of internal (stored) phosphorus levels. The verification provided through a satisfactory fit of model output to field measurements of phosphorus and gross photosynthesis established a conceptual foundation for empirical models relating phosphorus and trophic state parameters. Phosphorus concentrations corresponding to boundary conditions for trophic state categories were developed based on the verified models by defining oligotrophy as the region of linear response by growth rate to increases in phosphorus (<1.2 μg soluble reactive phosphorus (SRP)∙L−1, <11.5 μg total phosphorus (TP)∙L−1), mesotrophy as the transitional state (1.2–8.0 μg SRP∙L−1, 11.5–37.5 μg TP∙L−1), and eutrophy as the region where growth rate is saturated, i.e. insensitive to changes in phosphorus concentration (>8.0 μg SRP∙L−1, >37.5 μg TP∙L−1). We applied the trophic state classification scheme to several Great Lakes basins to examine their sensitivity to changes in phosphorus levels. The oligotrophic waters of Lakes Superior, Huron, and Michigan and northern Green Bay and Georgian Bay have the greatest sensitivity to increases in total phosphorus concentration. The eutrophic waters of southern Green Bay, western Lake Erie, and nearshore Lake Ontario are nutrient saturated and relatively insensitive to initial reductions in phosphorus levels. Offshore Lake Ontario, eastern and central Lake Erie, Saginaw Bay, and mid Green Bay lie in the transitional phase for sensitivity to phosphorus management.
Nutrient Enrichment Studies in a Coastal Plain Estuary: Phytoplankton Growth in Large-Scale, Continuous Cultures
Authors: D'Elia Christopher F. , Sanders James G. , Boynton Walter R.
Published: July 2010

The response of phytoplanktonic growth to experimental nutrient addition in a tributary of the Chesapeake Bay estuary varied with season and nutrient availability. In bioassay experiments employing outdoor 0.5-m3 continuous cultures freshly inoculated with natural phytoplankton from the Patuxent River estuary, supplements of N, either as ammonium or nitrate, enhanced growth greatly during the low-flow, late-summer season — a period when N:P ratios of dissolved inorganic nutrient standing stocks are characteristically below 5:1 (by atoms). Growth response to N addition was very rapid (1 d after the start of an experiment), implying that phytoplankton in the bioassay were N limited when removed from the estuary. PO43− addition enhanced phytoplankton growth during the late-winter, high-flow season, when N: P ratios (as previous) typically exceed 90:1 (by atoms), but the response lagged enrichment by at least 4 d and biomass levels achieved in these cultures were less than one third of those achieved in the N-enriched cultures during the late summer. The great seasonal variability in river flow, nutrient regimes, and the response of natural phytoplankton assemblages to nutrient enrichment in the Patuxent, and similar estuaries, suggest that management strategies to improve "water quality" will need to consider N as well as P additions.
Zooplankton Species Abundance and Biomass in Relation to Occurrence of Mysis relicta (Malacostraca: Mysidacea)
Authors: Nero Redwood W. , Sprules W. Gary
Published: July 2010

Year-long comparisons of the occurrence and abundance of zooplankton between two lakes where Mysis relicta is endemic and two where it is not show that in the former, hypolimnetic species Daphnia longiremis, Euhosmina longispina, Cyclops scutifer, and Diaptomus sanguineus are rare. Five other cladocerans were also lower in abundance in hypolimnetic strata and during isothermal conditions. Diaphanosoma spp. were more abundant in the metalimnion of lakes with Mysis; we suggest a competitive release through Mysis predation on Daphnia. Because each pair of lakes is comparable with respect to morphometry and chemistry, nonpredatory influences do not account for the observed distribution of zooplankton. Such species differences are also identical to trends occurring in a canonical analysis of zooplankton abundance for 497 lakes in eastern Ontario and western Quebec and corroborate declines in Cladocera associated with introductions of M. relicta into lakes and reservoirs.
Influence of Salmonine Predation and Weather on Long-Term Water Quality Trends in Lake Michigan
Authors: Scavia Donald , Fahnenstiel Gary L. , Evans Marlene S. , Jude David J. , Lehman John T.
Published: July 2010

Trends in Lake Michigan water quality over 1975–84 appear to reflect reduced nutrient loadings as indicated by gradual declines in spring total phosphorus (TP) and summer epilimnetic chlorophyll a (Chl a). Deviations from these trends during 1977 and 1983–84 were apparently caused by abiotic and biotic factors, respectively. Prolonged ice cover during 1977 decreased sediment resuspension resulting in lower TP, reduced Chl a levels, and increased water clarity. A similar dramatic result occurred in 1983 and to a lesser extent in 1984, but via a different mechanism. Burgeoning populations of stocked salmonines reduced populations of the planktivorous alewife (Alosa pseudoharengus), which allowed large Daphnia to flourish. Because the Daphnia are more voracious and nonselective grazers than the formerly dominant calanoid copepods, they reduced seston concentrations, causing dramatic increases in Secchi disk transparency. These exceptions demonstrate the far-reaching consequences that unusual weather conditions and fish management practices may have on water quality indicators.
Possible Effects of the Sitka Eddy on Sockeye (Oncorhynchus nerka) and Pink Salmon (Oncorhynchus gorbuscha) Migration off Southeast Alaska
Authors: Hamilton Kevin , Mysak Lawrence A.
Published: July 2010

The interannual variability of sockeye (Oncorhynchus nerka) and pink salmon (Oncorhynchus gorbuscha) catches during 1952–62 from southeast Alaska and northern British Columbia is examined in relation to the appearance and disappearance of the Sitka eddy in the offshore oceanic circulation. In years when this large (~300 km in diameter) and intense (surface currents ~0.5 m/s) vortex is present, the spawning migration routes of salmon returning to the Nass and Skeena rivers tend to be deflected southward. An analysis of salmon tagging data collected during 1957 (when the eddy was absent) and 1958 (when the eddy was present) supports this conclusion. The southward deflection during 1958 is a particularly interesting result in light of many other observations which show that several fish species were displaced northward during the 1958 warming of the northeast Pacific Ocean.
Uncertainty in 2-D hydraulic modeling: a case study of an experiment in transcritical flowThis article is one of a selection of papers published in this Special Issue on Hydrotechnical Engineering.
Authors: Lewicki L. , Paquier A. , El kadi Abderrezzak K. , Rivière N.
Published: July 2010

Change in flow regime from subcritical to supercritical flow or opposite can be met during a dam break flow propagation but also during floods in urban areas, particularly near crossroads. Detailed laboratory measurements of flow discharge distribution and flow depths are carried out for transcritical dividing flows in a 90° sharp-edged, rectangular junction formed by horizontal open-channels of equal width. These measurements are used to assess the uncertainty of numerical predictions obtained using a two-dimensional (2-D) depth-averaged model. A sensitivity analysis to four parameters, i.e., space step, friction coefficient, diffusion coefficient, and downstream boundary condition, is carried out. For the water depths in the vicinity of the intersection, uncertainty linked to the calibration of the four aforementioned parameters can be higher than 50% because of the difficulty in representing the location and amplitude of the hydraulic jumps while, for the flow ratio between the downstream branches, uncertainty is limited to 10%.