bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of Fatigue Crack Initiation/Propagation and Daisy-Chain Resistance in Lead-Free Solder Joints Under Temperature Cycling Test
Authors: Chan Y. Sing , Song F. B. , Lee S. W. Ricky , Yang C. R. , Lo Jeffery C. C.
Published: February 2012

It has been a common practice in the microelectronics industry to evaluate the long-term solder joint reliability using the accelerated temperature cycling (ATC) test. The thermal fatigue failure mechanism of solder joints during the ATC test involves the initiation of microcracks and, subsequently, their propagation and coalescence for a complete joint separation. Traditionally, the industry employs methods based on the measurement of the daisy-chain resistance to monitor the failure of the solder joints. Yet, there is no specific study to investigate the relationship between the resistance change during the ATC test and the crack formation of the solder fatigue. This study aims to provide an experimental investigation on such relationship. A custom-made sample is designed and fabricated in the study. The fatigue crack growth in solder joints of certain custom-made assemblies can be directly inspected during the test. The daisy-chain resistance is real-time monitored. The test results reveal that the electrical resistance monitoring approach is not effective in detecting the fatigue crack initiation and subsequent propagation. As a result, a partially degraded interconnect cannot be identified. Therefore, new monitoring methods should be developed for this purpose.
Numerical Simulations of Electromigration and Stress Migration Driven Void Propagation in Pb Free Solder Interconnects
Authors: Sadasiva Subramanya , Subbarayan Ganesh , Jiang Lei , Pantuso Daniel
Published: February 2012

Increasing miniaturization has led a significant increase in the current densities seen in flip-chip solder joints. This has made the study of failure in solder joints by void propagation due to electromigration and stress migration more important. In this study, we develop a phase field model for the motion of voids through a flip chip solder interconnect. We derive equations of motion for the void accounting for energetic contributions from the active factors of surface energy, stress and electric potential, taking into account both surface diffusion and transfer of the material through the bulk of the material. We describe the implementation of this model using finite elements, coupled with a commercial finite element solver to solve for the fields driving the void motion.
Thermal Conductivity Reduction in Few-Layer Graphene
Authors: Singh Dhruv , Murthy Jayathi Y. , Fisher Timothy S.
Published: February 2012

Using the linearized Boltzmann transport equation and perturbation theory, we analyze the reduction in the intrinsic thermal conductivity of few-layer graphene sheets accounting for all possible three-phonon scattering events. Even with weak coupling between layers, a significant reduction in the thermal conductivity of the out-of-plane acoustic modes is apparent. The main effect of this weak coupling is to open many new three-phonon scattering channels that are otherwise absent in graphene. The highly restrictive selection rule that leads to a high thermal conductivity of ZA phonons in single-layer graphene is only weakly broken with the addition of multiple layers, and ZA phonons still dominate thermal conductivity. We also find that the decrease in thermal conductivity is mainly caused by decreased contributions of the higher-order overtones of the fundamental out-of-plane acoustic mode. Moreover, the extent of reduction is largest when going from single to bilayer graphene and saturates for four layers. The results compare remarkably well over the entire temperature range with measurements of of graphene and graphite.
Comment on “A Diverse Assemblage of Late Cretaceous Dinosaur and Bird Feathers from Canadian Amber”
Authors: Dove Carla J. , Straker Lorian C.
Published: February 2012

McKellar
et al
. (Reports, 16 September 2011, p. 1619) analyzed Late Cretaceous amber specimens from Canada and identified some filaments as dinosaurian protofeathers. We argue that their analysis and data do not provide sufficient evidence to conclude that such filaments are feather-like structures. Further investigation, including destructive sampling, must be carried out for more convincing conclusions.
James F. Crow (1916–2012)
Authors: Dove William , Susman Millard
Published: February 2012

A population geneticist is remembered by colleagues for his generosity, clarity, and influence in the field, as well as in policy matters involving genetics.
Science Spared Brunt of Ax in Budget Request
Authors: Mervis Jeffrey
Published: February 2012

While legislators are demanding big cuts in federal spending, President Barack Obama sent Congress a clear message in the 2013 budget he submitted this week: Don't cut research.
Does Forewarned = Forearmed With Lab-Made Avian Influenza Strains?
Authors: Cohen Jon
Published: February 2012

The debate over whether journals should publish the full details of how two labs engineered the deadly avian influenza strain H5N1 so that it spreads more easily among ferrets, and presumably humans, shows that knowledge cuts both ways.
Validation of a Single-Platform, Volumetric, CD45-Assisted PanLeucogating Auto40 Flow Cytometer To Determine the Absolute Number and Percentages of CD4 T Cells in Resource-Constrained Settings Using Cameroonian Patients' Samples
Authors: Mbopi-Kéou François-Xavier , Mion Stefano , Sagnia Bertrand , Bélec Laurent
Published: February 2012

The study evaluated the single-platform, volumetric, CD45-assisted PanLeucogating Auto40 flow cytometer (Apogee Flow Systems Ltd., Hemel Hempstead, United Kingdom) for CD4 T cell numeration, compared to the reference FACSCalibur flow cytometer. Results of absolute counts and percentages of CD4 T cells by Auto40 and FACSCalibur of 234 tripotassium EDTA (K3-EDTA)-blood samples from 146 adults and 88 children (aged from 18 months to 5 years), living in Yaoundé, Cameroon, were highly correlated (r2= 0.97 andr2= 0.98, respectively). The mean absolute bias and relative bias between Apogee Auto40 and FACSCalibur absolute CD4 T cell counts were +9.6 cells/μl, with limits of agreement from −251 to 270 cells/μl, and +4.1%, with limits of agreement from −16.1 to 24.4%, respectively. The mean absolute bias and relative bias between Apogee Auto40 and FACSCalibur CD4 T cell results expressed as percentages were +0.05% CD4 (95% confidence interval [CI], −0.03 to 0.41), with limits of agreement from −6.0 to 5.9% CD4, and +1.0%, with limits of agreement from −32.3 to 34.4%, respectively. The Auto40 counting allowed identification of the majority of adults with CD4 T cell counts below 200 cells/μl (sensitivity, 87%; specificity, 98%) or below 350 cells/μl (sensitivity, 92%; specificity, 98%) and of children with CD4 T cell counts below 750 cells/μl (sensitivity, 82%; specificity, 98%) or below 25% CD4+(sensitivity, 96%; specificity, 99%). The Auto40 analyzer is a reliable alternative flow cytometer for CD4 T lymphocyte enumeration to be used in routine immunological monitoring according to the WHO recommendations for HIV-infected adults as well as children living in resource-constrained settings.
Concurrent Occurrence of
bla
ampC
Families and
bla
CTX-M
Genogroups and Association with Mobile Genetic Elements IS
Ecp1
, IS
26
, IS
CR1
, and
sul1
-Type Class 1 Integrons in Escherichia coli and Klebsiella pneumoniae Isolates Originating from India
Authors: Shahid Mohammed , Sobia Farrukh , Singh Anuradha , Khan Haris M.
Published: February 2012

Cefoxitin-resistant
Escherichia coli
(
n
= 109) and
Klebsiella pneumoniae
(
n
= 16) isolates collected from patients in India in 2009 to 2010 were screened for
bla
ampC
families and mobilizing elements (
ISE
cp1,
IS
26,
IS
CR1, and
sul
-1-type class 1 integrons) and their association with
bla
ampC
and for the occurrence of class A beta-lactamases (BLs) (CTX-M, TEM, and SHV). The concurrent occurrences of two distinct AmpC families (
bla
CIT
and
bla
EBC
) and of class A with class C beta-lactamase were observed. All but one of the isolates harboring CTX-M extended-spectrum BLs (ESBLs) were carrying
bla
CTX-M
genogroup 1; the remaining isolate carried
bla
CTX-M
genogroup 9. The mobilizing elements occurred in different combinations in the study isolates.
Cutaneous Infection Caused by Gordonia amicalis after a Traumatic Injury
Authors: Lai Chih-Cheng , Hsieh Jung-Hsien , Tsai Hsih-Yeh , Liao Chun-Hsing , Hsueh Po-Ren
Published: February 2012

Gordonia amicalis
infection has never been reported in humans. We report here the first case of
G. amicalis
-related cutaneous infection after a traumatic injury. The isolate was confirmed by 16S rRNA sequencing analysis, and the patient responded well to repeated debridement and antibiotic treatment.
Analysis of Pathogen and Host Factors Related to Clinical Outcomes in Patients with Hospital-Acquired Pneumonia Due to Methicillin-Resistant Staphylococcus aureus
Authors: Haque Nadia Z. , Arshad Samia , Peyrani Paula , Ford Kimbal D. , Perri Mary B. , Jacobsen Gordon , Reyes Katherine , Scerpella Ernesto G. , Ramirez Julio A. , Zervos Marcus J.
Published: February 2012

Methicillin-resistant
Staphylococcus aureus
(MRSA) is a major cause of nosocomial pneumonia. To characterize pathogen-derived and host-related factors in intensive care unit (ICU) patients with MRSA pneumonia, we evaluated the Improving Medicine through Pathway Assessment of Critical Therapy in Hospital-Acquired Pneumonia (IMPACT-HAP) database. We performed multivariate regression analyses of 28-day mortality and clinical response using univariate analysis variables at a
P
level of <0.25. In isolates from 251 patients, the most common molecular characteristics were USA100 (55.0%) and USA300 (23.9%), SCC
mec
types II (64.1%) and IV (33.1%), and
agr
I (36.7%) and II (61.8%). Panton-Valentine leukocidin (PVL) was present in 21.9%, and vancomycin heteroresistance was present in 15.9%. Mortality occurred in 37.1% of patients; factors in the univariate analysis were age, APACHE II score, AIDS, cardiac disease, vascular disease, diabetes, SCC
mec
type II, PVL negativity, and higher vancomycin MIC (all
P
values were <0.05). In multivariate analysis, independent predictors were APACHE II score (odds ratio [OR], 1.090; 95% confidence interval [CI], 1.041 to 1.141;
P
< 0.001) and age (OR, 1.024; 95% CI, 1.003 to 1.046;
P
= 0.02). Clinical failure occurred in 36.8% of 201 evaluable patients; the only independent predictor was APACHE II score (OR, 1.082; 95% CI, 1.031 to 1.136;
P
= 0.002). In summary, APACHE II score (mortality, clinical failure) and age (mortality) were the only independent predictors, which is consistent with severity of illness in ICU patients with MRSA pneumonia. Interestingly, our univariate findings suggest that both pathogen and host factors influence outcomes. As the epidemiology of MRSA pneumonia continues to evolve, both pathogen- and host-related factors should be considered when describing epidemiological trends and outcomes of therapeutic interventions.
Real-Time Multiplex PCR for Detecting Shiga Toxin 2-Producing Escherichia coli O104:H4 in Human Stools
Authors: Zhang Wenlan , Bielaszewska Martina , Bauwens Andreas , Fruth Angelika , Mellmann Alexander , Karch Helge
Published: February 2012

A real-time multiplex PCR targeting
stx
2
,
wzy
O104
, and
fliC
H4
of enterohemorrhagic
Escherichia coli
(EHEC) O104:H4 correctly determined the presence or absence of these genes in 253 EHEC isolates and enrichment cultures of stool samples from 132 patients. It is a rapid, sensitive, and specific tool for detecting EHEC O104:H4 in human stools.
Tracking Viral Evolution during a Disease Outbreak: the Rapid and Complete Selective Sweep of a Circovirus in the Endangered Echo Parakeet
Authors: Kundu Samit , Faulkes Christopher G. , Greenwood Andrew G. , Jones Carl G. , Kaiser Pete , Lyne Owen D. , Black Simon A. , Chowrimootoo Aurelie , Groombridge Jim J.
Published: February 2012

Circoviruses are among the smallest and simplest of all viruses, but they are relatively poorly characterized. Here, we intensively sampled two sympatric parrot populations from Mauritius over a period of 11 years and screened for the circovirusBeak and feather disease virus(BFDV). During the sampling period, a severe outbreak of psittacine beak and feather disease, which is caused by BFDV, occurred in Echo parakeets. Consequently, this data set presents an ideal system for studying the evolution of a pathogen in a natural population and to understand the adaptive changes that cause outbreaks. Unexpectedly, we discovered that the outbreak was most likely caused by changes in functionally important regions of the normally conservedreplication-associated proteingene and not the immunogeniccapsid. Moreover, these mutations were completely fixed in the Echo parakeet host population very shortly after the outbreak. Severalcapsidalleles were linked to thereplication-associated proteinoutbreak allele, suggesting that whereas the key changes occurred in the latter, the scope of the outbreak and the selective sweep may have been influenced by positive selection in the capsid. We found evidence for viral transmission between the two host populations though evidence for the invasive species as the source of the outbreak was equivocal. Finally, the high evolutionary rate that we estimated shows how rapidly new variation can arise in BFDV and is consistent with recent results from other small single-stranded DNA viruses.
The PI3K/Akt Pathway Contributes to Arenavirus Budding
Authors: Urata Shuzo , Ngo Nhi , de la Torre Juan Carlos
Published: February 2012

Several arenaviruses, chiefly Lassa virus (LASV), cause hemorrhagic fever (HF) disease in humans and pose a significant public health concern in regions where they are endemic. On the other hand, evidence indicates that the globally distributed prototypic arenavirus lymphocytic choriomeningitis virus (LCMV) is a neglected human pathogen. The phosphatidylinositol 3-kinase (PI3K)/Akt pathway participates in many cellular processes, including cell survival and differentiation, and also has been shown to play important roles in different steps of the life cycles of a variety of viruses. Here we report that the inhibition of the PI3K/Akt pathway inhibited budding and to a lesser extent RNA synthesis, but not cell entry, of LCMV. Accordingly, BEZ-235, a PI3K inhibitor currently in cancer clinical trials, inhibited LCMV multiplication in cultured cells. These findings, together with those previously reported for Junin virus (JUNV), indicate that targeting the PI3K/Akt pathway could represent a novel antiviral strategy to combat human-pathogenic arenaviruses.
Host Acyl Coenzyme A Binding Protein Regulates Replication Complex Assembly and Activity of a Positive-Strand RNA Virus
Authors: Zhang Jiantao , Diaz Arturo , Mao Lan , Ahlquist Paul , Wang Xiaofeng
Published: February 2012

All positive-strand RNA viruses reorganize host intracellular membranes to assemble their replication complexes. Similarly, brome mosaic virus (BMV) induces two alternate forms of membrane-bound RNA replication complexes: vesicular spherules and stacks of appressed double-membrane layers. The mechanisms by which these membrane rearrangements are induced, however, remain unclear. We report here that host ACB1-encoded acyl coenzyme A (acyl-CoA) binding protein (ACBP) is required for the assembly and activity of both BMV RNA replication complexes. ACBP is highly conserved among eukaryotes, specifically binds to long-chain fatty acyl-CoA, and promotes general lipid synthesis. Deleting ACB1 inhibited BMV RNA replication up to 30-fold and resulted in formation of spherules that were ∼50% smaller but ∼4-fold more abundant than those in wild-type (wt) cells, consistent with the idea that BMV 1a invaginates and maintains viral spherules by coating the inner spherule membrane. Furthermore, smaller and more frequent spherules were preferentially formed under conditions that induce layer formation in wt cells. Conversely, cellular karmella structures, which are arrays of endoplasmic reticulum (ER) membranes formed upon overexpression of certain cellular ER membrane proteins, were formed normally, indicating a selective inhibition of 1a-induced membrane rearrangements. Restoring altered lipid composition largely complemented the BMV RNA replication defect, suggesting that ACBP was required for maintaining lipid homeostasis. Smaller and more frequent spherules are also induced by 1a mutants with specific substitutions in a membrane-anchoring amphipathic α-helix, implying that the 1a-lipid interactions play critical roles in viral replication complex assembly.
Receptor-Binding Profiles of H7 Subtype Influenza Viruses in Different Host Species
Authors: Gambaryan Alexandra S. , Matrosovich Tatyana Y. , Philipp Jennifer , Munster Vincent J. , Fouchier Ron A. M. , Cattoli Giovanni , Capua Ilaria , Krauss Scott L. , Webster Robert G. , Banks Jill , Bovin Nicolai V. , Klenk Hans-Dieter , Matrosovich Mikhail N.
Published: February 2012

Influenza viruses of gallinaceous poultry and wild aquatic birds usually have distinguishable receptor-binding properties. Here we used a panel of synthetic sialylglycopolymers and solid-phase receptor-binding assays to characterize receptor-binding profiles of about 70 H7 influenza viruses isolated from aquatic birds, land-based poultry, and horses in Eurasia and America. Unlike typical duck influenza viruses with non-H7 hemagglutinin (HA), all avian H7 influenza viruses, irrespective of the host species, displayed a poultry-virus-like binding specificity, i.e., preferential binding to sulfated oligosaccharides Neu5Acα2-3Galβ1-4(6-O-HSO3)GlcNAc and Neu5Acα2-3Galβ1-4(Fucα1-3)(6-O-HSO3)GlcNAc. This phenotype correlated with the unique amino acid sequence of the amino acid 185 to 189 loop of H7 HA and seemed to be dependent on ionic interactions between the sulfate group of the receptor and Lys193 and on the lack of sterical clashes between the fucose residue and Gln222. Many North American and Eurasian H7 influenza viruses displayed weak but detectable binding to the human-type receptor moiety Neu5Acα2-6Galβ1-4GlcNAc, highlighting the potential of H7 influenza viruses for avian-to-human transmission. Equine H7 influenza viruses differed from other viruses by preferential binding to the N-glycolyl form of sialic acid. Our data suggest that the receptor-binding site of contemporary H7 influenza viruses in aquatic and terrestrial birds was formed after the introduction of their common precursor from ducks to a new host, presumably, gallinaceous poultry. The uniformity of the receptor-binding profile of H7 influenza viruses in various wild and domestic birds indicates that there is no strong receptor-mediated host range restriction in birds on viruses with this HA subtype. This notion agrees with repeated interspecies transmission of H7 influenza viruses from aquatic birds to poultry.
Susceptibility to Acute Mouse Adenovirus Type 1 Respiratory Infection and Establishment of Protective Immunity in Neonatal Mice
Authors: Procario Megan C. , Levine Rachael E. , McCarthy Mary K. , Kim Eunnie , Zhu Lingqiao , Chang Cheong-Hee , Hershenson Marc B. , Weinberg Jason B.
Published: February 2012

There is an incomplete understanding of the differences between neonatal immune responses that contribute to the increased susceptibility of neonates to some viral infections. We tested the hypothesis that neonates are more susceptible than adults to mouse adenovirus type 1 (MAV-1) respiratory infection and are impaired in the ability to generate a protective immune response against a second infection. Following intranasal infection, lung viral loads were greater in neonates than in adults during the acute phase but the virus was cleared from the lungs of neonates as efficiently as it was from adult lungs. Lung gamma interferon (IFN-γ) responses were blunted and delayed in neonates, and lung viral loads were higher in adult IFN-γ−/−mice than in IFN-γ+/+controls. However, administration of recombinant IFN-γ to neonates had no effect on lung viral loads. Recruitment of inflammatory cells to the airways was impaired in neonates. CD4 and CD8 T cell responses were similar in the lungs of neonates and adults, although a transient increase in regulatory T cells occurred only in the lungs of infected neonates. Infection of neonates led to protection against reinfection later in life that was associated with increased effector memory CD8 T cells in the lungs. We conclude that neonates are more susceptible than adults to acute MAV-1 respiratory infection but are capable of generating protective immune responses.
Impact of Human Adenovirus Type 3 Dodecahedron on Host Cells and Its Potential Role in Viral Infection
Authors: Fender Pascal , Hall Kathryn , Schoehn Guy , Blair G. Eric
Published: February 2012

During human adenovirus type 3 (Ad3) infection, an excess of penton base and fiber proteins are produced which form dodecahedral particles composed of 12 pentamers of penton base and 12 trimers of fiber protein. No biological functions have yet been ascribed to Ad3 dodecahedra. Here, we show that dodecahedra compete with Ad3 virions for binding to the cell surface and trigger cell remodeling, giving new insights into possible biological functions of dodecahedra in the Ad3 infectious cycle.
Biological Characterization and Next-Generation Genome Sequencing of the Unclassified Cotia Virus SPAn232 (Poxviridae)
Authors: Afonso Priscila P. , Silva Patrícia M. , Schnellrath Laila C. , Jesus Desyreé M. , Hu Jianhong , Yang Yajie , Renne Rolf , Attias Marcia , Condit Richard C. , Moussatché Nissin , Damaso Clarissa R.
Published: February 2012

Cotia virus (COTV) SPAn232 was isolated in 1961 from sentinel mice at Cotia field station, São Paulo, Brazil. Attempts to classify COTV within a recognized genus of the
Poxviridae
have generated contradictory findings. Studies by different researchers suggested some similarity to myxoma virus and swinepox virus, whereas another investigation characterized COTV SPAn232 as a vaccinia virus strain. Because of the lack of consensus, we have conducted an independent biological and molecular characterization of COTV. Virus growth curves reached maximum yields at approximately 24 to 48 h and were accompanied by virus DNA replication and a characteristic early/late pattern of viral protein synthesis. Interestingly, COTV did not induce detectable cytopathic effects in BSC-40 cells until 4 days postinfection and generated viral plaques only after 8 days. We determined the complete genomic sequence of COTV by using a combination of the next-generation DNA sequencing technologies 454 and Illumina. A unique contiguous sequence of 185,139 bp containing 185 genes, including the 90 genes conserved in all chordopoxviruses, was obtained. COTV has an interesting panel of open reading frames (ORFs) related to the evasion of host defense, including two novel genes encoding C-C chemokine-like proteins, each present in duplicate copies. Phylogenetic analysis revealed the highest amino acid identity scores with
Cervidpoxvirus
,
Capripoxvirus
,
Suipoxvirus
,
Leporipoxvirus
, and
Yatapoxvirus
. However, COTV grouped as an independent branch within this clade, which clearly excluded its classification as an
Orthopoxvirus
. Therefore, our data suggest that COTV could represent a new poxvirus genus.
Feasibility study of geospatial mapping of chronic disease risk to inform public health commissioning
Authors: Noble Douglas , Smith Dianna , Mathur Rohini , Robson John , Greenhalgh Trisha
Published: February 2012

Objective

To explore the feasibility of producing small-area geospatial maps of chronic disease risk for use by clinical commissioning groups and public health teams.

Study design

Cross-sectional geospatial analysis using routinely collected general practitioner electronic record data.

Sample and setting

Tower Hamlets, an inner-city district of London, UK, characterised by high socioeconomic and ethnic diversity and high prevalence of non-communicable diseases.

Methods

The authors used type 2 diabetes as an example. The data set was drawn from electronic general practice records on all non-diabetic individuals aged 25–79 years in the district (n=163 275). The authors used a validated instrument, QDScore, to calculate 10-year risk of developing type 2 diabetes. Using specialist mapping software (ArcGIS), the authors produced visualisations of how these data varied by lower and middle super output area across the district. The authors enhanced these maps with information on examples of locality-based social determinants of health (population density, fast food outlets and green spaces). Data were piloted as three types of geospatial map (basic, heat and ring). The authors noted practical, technical and information governance challenges involved in producing the maps.

Results

Usable data were obtained on 96.2% of all records. One in 11 adults in our cohort was at ‘high risk’ of developing type 2 diabetes with a 20% or more 10-year risk. Small-area geospatial mapping illustrated ‘hot spots’ where up to 17.3% of all adults were at high risk of developing type 2 diabetes. Ring maps allowed visualisation of high risk for type 2 diabetes by locality alongside putative social determinants in the same locality. The task of downloading, cleaning and mapping data from electronic general practice records posed some technical challenges, and judgement was required to group data at an appropriate geographical level. Information governance issues were time consuming and required local and national consultation and agreement.

Conclusions

Producing small-area geospatial maps of diabetes risk calculated from general practice electronic record data across a district-wide population was feasible but not straightforward. Geovisualisation of epidemiological and environmental data, made possible by interdisciplinary links between public health clinicians and human geographers, allows presentation of findings in a way that is both accessible and engaging, hence potentially of value to commissioners and policymakers. Impact studies are needed of how maps of chronic disease risk might be used in public health and urban planning.
HIV testing and care systems focused on sexually transmitted HIV in China
Authors: Tucker Joseph D , Wong Frank Y , Nehl Eric J , Zhang Fujie
Published: February 2012

Background

Over three-quarters of new HIV infections in China during 2009 were estimated to be from sexual transmission. Over half of those living with HIV do not know their serostatus and identifying and treating individuals with sexually transmitted HIV infection has been challenging.

Objective

This global assessment explores Chinese systems for detecting and treating those with HIV infection with a particular focus on groups at increased risk of sexually transmitted HIV.

Methods

Published literature, grey sources and non-governmental reports were reviewed to describe HIV testing and care systems in China.

Results

HIV testing and care in China involve several parallel health systems and have been largely successful in reaching large numbers of vulnerable individuals. Provider-initiated testing and counselling has been more effective than voluntary counselling and testing programmes for expanding HIV testing efforts in China. Individuals with sexually transmitted HIV infection are underrepresented in the antiretroviral care system compared with other high-risk groups.

Conclusions

Comprehensive HIV testing and care bring together a number of Chinese health systems, but there are still gaps and challenges. Research and programmes focused on HIV testing and care for those with increased sexual risk are needed.
A novel HIV treatment model using private practitioners in South Africa
Authors: Innes Craig , Hamilton Robin , Hoffmann Christopher J , Hippner Piotr , Fielding Katherine , Grant Alison D , Churchyard Gavin J , Charalambous Salome
Published: February 2012

Objectives

The extent of the HIV epidemic in South Africa may render the public sector capacity inadequate to manage all patients requiring antiretroviral treatment (ART). Private practitioners are an underutilised resource.

Methods

The authors developed a model of care using 72 private practitioners in five provinces in urban and rural areas of South Africa with centralised clinical support, training, pharmacy control and data management. The authors describe the programme, its quality control measures and patient outcomes using a cohort analysis.

Results

Between January 2005 and December 2008, 9102 individuals were started on ART, 62% female, median age 34 years, median viral load 50 655 copies/ml and median baseline CD4 count 123 cells/μl. Retention (alive and in care) after 12 months was 63% in the 2005 cohort (646 of 1026) and remained similar in the other calendar years, 58%, 68% and 64% in 2006, 2007 and 2008, respectively. After 36 months, retention was 50% and 41% for those enrolled in 2005 and 2006, respectively. The percentage virally suppressed remained similar at 6 months, 82% vs 84%, 84% and 85% from 2005, 2006, 2007 to 2008, respectively, p=0.66; but improved slightly at 12 months, 78% vs 83%, 83% and 84% from 2005 to 2008, p=0.05. At 36 months, it was 84% and 82% for the 2005 and 2006 cohorts, respectively.

Conclusions

The results show that a well-managed private practitioner model can achieve comparable results to public services, although long-term retention needs further evaluation. This model of ART delivery can be used to expand access to ART in areas where the public sector is unable to meet the demand.
CHAOTIC CHARACTERISTIC ANALYSIS OF STRONG EARTHQUAKE GROUND MOTIONS
Authors: YANG DIXIONG , YANG PIXIN , ZHANG CHANGGENG
Published: February 2012

This paper aims to analyze and understand the irregularity and complexity of earthquake ground motions from the perspective of nonlinear dynamics. Chaotic dynamics theory and chaotic time series analysis are suggested to examine the nonlinear dynamical characteristic of strong earthquake ground motions. Based on the power spectral analysis, principal component analysis and modified false nearest neighbors method, it is illustrated qualitatively that the acceleration time series of earthquake ground motions exhibit chaotic property. Next, the chaotic time series analysis is proposed to calculate quantitatively the nonlinear characteristic parameters of acceleration time histories of near-fault ground motions. Numerical results show that the correlation dimension of these ground motions is fractal dimension. Their Kolmogorov entropy is a limited positive value, and their maximal Lyapunov exponent is larger than 0. It is demonstrated that the strong earthquake ground motions present the chaotic property rather than the pure random signals, and the severe irregularity and complexity of ground motions are the reflection of high nonlinearity of earthquake physical process.
IDENTIFYING NONSTATIONARY JAMMING SIGNAL VIA LAGRANGIAN COHERENT STRUCTURES
Authors: MA HONG-GUANG , JIANG QIN-BO , KONG XIANG-YU , LIU ZHI-QIANG , MA ZHI-YUAN
Published: February 2012

The anti-jamming scheme is an important issue in the modern communication system, where the spread-spectrum signals are usually adopted. In a complex electromagnetic environment where the jamming sources may be close to the communication devices, a large jamming-to-signal ratio is possible. How to achieve the desired accuracy for the communication system in the presence of strong jamming is a crucial and outstanding problem. To solve this problem, we propose a method to identify the desired signal and the nonstationary jamming signal via Lagrangian Coherent Structures (LCS), and a new algorithm for calculating the maximum Finite-Time Lyapunov Exponent (FTLE) is presented. As opposed to the current approach which requires a vector field in the state space at each instant time, the proposed algorithm is performed on the vector fields which are respectively built on the desired signal and the nonstationary jamming signal via Hilbert Transform. A simulation test is conducted on a binary offset carrier (BOC) modulated signal and a chirp signal. The results indicate that the proposed method can provide new features to efficiently identify the nonstationary jamming signal.
INTERMITTENCY AND INTERIOR CRISIS AS ROUTE TO CHAOS IN DYNAMIC WALKING OF TWO BIPED ROBOTS
Authors: GRITLI HASSENE , BELGHITH SAFYA , KHRAEIF NAHLA
Published: February 2012

Recently, passive and semi-passive dynamic walking has been noticed in researches of biped walking robots. Such biped robots are well-known that they demonstrate only a period-doubling route to chaos while walking down sloped surfaces. In previous researches, such route was shown with respect to a continuous change in some parameter of the biped robot. In this paper, two biped robots are introduced: the passive compass-gait biped robot and the semi-passive torso-driven biped robot. The period-doubling scenario route to chaos is revisited for the first biped as the ground slope changes. Furthermore, we will show through bifurcation diagram that the torso-driven biped exhibits also such route to chaos when the slope angle is varied. For such biped, a modified semi-passive control law is introduced in order to stabilize the torso at some desired position.

In this work, we will show through bifurcation diagrams that the dynamic walking of the two biped robots reveals two other routes to chaos namely the intermittency route and the interior crisis route. We will stress that the intermittency is generated via a saddle-node bifurcation where an unstable periodic orbit is created. We will highlight that such event takes place for a Type-I intermittency. However, we will emphasize that the interior crisis event occurs when a collision of the unstable periodic orbit with a weak chaotic attractor happens giving rise to a strong chaotic attractor. In addition, we will explore the intermittent step series induced by the interior crisis and also by the Type-I intermittency. In this study, our analysis on chaos and the routes to chaos will be based, beside bifurcation diagrams, on Lyapunov exponents and fractal (Lyapunov) dimension. These two tools are plotted in the parameter space to classify attractors observed in bifurcation diagrams.
DEGENERATE HOPF BIFURCATION IN NONSMOOTH PLANAR SYSTEMS
Authors: LIANG FENG , HAN MAOAN
Published: February 2012

In this paper, we mainly discuss Hopf bifurcation for planar nonsmooth general systems and Liénard systems with foci of parabolic–parabolic (PP) or focus–parabolic (FP) type. For the bifurcation near a focus, when the focus is kept fixed under perturbations we prove that there are at most k limit cycles which can be produced from an elementary weak focus of order 2k + 2 ( resp. k + 1)(k ≥ 1) if the focus is of PP (resp. FP) type, and we present the conditions to ensure these upper bounds are achievable. For the bifurcation near a center, the Hopf cyclicicy is studied for these systems. Some interesting applications are presented.
WE PROBABLY LIVE ON AN INFLATING BRANE-WORLD
Authors: NEUPANE ISHWAREE P.
Published: February 2012

Brane-world models, where observers are trapped within the thickness of a 3-brane, offer novel perspectives on gravitation and cosmology. In this essay, it is argued that the problem of a late epoch acceleration of the universe is well explained in the framework of a 4-dimensional de Sitter universe embedded in a 5-dimensional de Sitter spacetime. While a 5-dimensional Anti-de Sitter space background is important for studying conformal field theories for its role in the AdS/CFT correspondence, the existence of a 5-dimensional de Sitter space is crucial for finding an effective 4-dimensional Newton constant that remains finite and a normalizable zero-mode graviton wave function.
UNCERTAINTY RELATIONS FOR COSMOLOGICAL PARTICLE CREATION AND EXISTENCE OF LARGE FLUCTUATIONS IN REHEATING
Authors: KAYA ALI
Published: February 2012

We derive an uncertainty relation for the energy density and pressure of a quantum scalar field in a time-dependent, homogeneous and isotropic, classical background, which implies the existence of large fluctuations comparable to their vacuum expectation values. A similar uncertainty relation is known to hold for the field square since the field can be viewed as a Gaussian random variable. We discuss possible implications of these results for the reheating process in scalar field driven inflationary models, where reheating is achieved by the decay of the coherently oscillating inflaton field. Specifically we argue that the evolution after backreaction can seriously be altered by the existence of these fluctuations. For example, in one model the coherence of the inflaton oscillations is found to be completely lost in a very short time after backreaction starts. Therefore we argue that entering a smooth phase in thermal equilibrium is questionable in such models and reheating might destroy the smoothness attained by inflation.
ON IMPLICATIONS OF EQUIVALENCE PRINCIPLE FOR MODIFIED GRAVITY THEORIES
Authors: SHEIKH-JABBARI M. M.
Published: February 2012

One of the manifestations of Einstein Equivalence Principle (EEP) is that a freely falling particle in a gravitational field is following a geodesic. In Einstein's general relativity (GR) this is built in the formulation by assuming the connection to be the Levi-Civita connection. The latter may, however, be demanded to be implied by the dynamics of a generic modified gravity theory, within the Palatini formulation. We show that for extensions of the Einstein GR which are described by a Lagrangian [Formula: see text], where gμν is the metric and Rμαβν is the Riemann curvature tensor, this manifestation of EEP is only fulfilled for a special class of Lagrangians, the Lovelock gravity theories. Our analysis also implies that within the above mentioned set of modified gravity theories only for Lovelock gravity theories metric and Palatini formulations are equivalent.
NONSINGULAR ORIGIN OF THE UNIVERSE AND THE COSMOLOGICAL CONSTANT PROBLEM
Authors: GUENDELMAN E. I.
Published: February 2012

We consider a nonsingular origin for the universe starting from an Einstein static universe in the framework of a theory which uses two volume elements [Formula: see text] and Φd4x, where Φ is a metric independent density, also curvature, curvature square terms, first order formalism and for scale invariance a dilaton field ϕ are considered in the action. In the Einstein frame we also add a cosmological term that parametrizes the zero point fluctuations. The resulting effective potential for the dilaton contains two flat regions, for ϕ → ∞ relevant for the nonsingular origin of the universe and ϕ → -∞, describing our present universe. Surprisingly, avoidance of singularities and stability as ϕ → ∞ imply a positive but small vacuum energy as ϕ → -∞. Zero vacuum energy density for the present universe is the "threshold" for universe creation.
OPERA-REASSESSING DATA ON THE ENERGY DEPENDENCE OF THE SPEED OF NEUTRINOS
Authors: AMELINO-CAMELIA GIOVANNI , GUBITOSI GIULIA , LORET NICCOLÓ , MERCATI FLAVIO , ROSATI GIACOMO , LIPARI PAOLO
Published: February 2012

We offer a preliminary exploration of the two sides of the challenge provided by the recent OPERA data on superluminal neutrinos. On one side we stress that some aspects of this result are puzzling even from the perspective of the wild quantum-gravity literature, where arguments in favor of the possibility of superluminal propagation have been presented, but not considering the possibility of such a sizeable effect for neutrinos of such low energies. We feel this must encourage particularly severe scrutiny of the OPERA result. On the other side, we notice that the OPERA result is reasonably consistent with μ-neutrino-speed data previously obtained at FERMILAB, reported in papers of 2007 and 1979. And it is intriguing that these FERMILAB79 and FERMILAB07 results, when combined with the new OPERA result, in principle provide a window on μ-neutrino speeds at different energies broad enough to compare alternative phenomenological models. We test the discriminating power of such an approach by using as illustrative examples the case of special-relativistic tachyons, the case of momentum-independent violations of the special-relativistic speed law, and the cases of linear and quadratic energy dependence of the speed of ultrarelativistic muon neutrinos. Even just using μ-neutrino data in the range from ~3 GeVs to ~200 GeVs the special-relativistic tachyon and the quadratic-dependence case are clearly disfavoured. The linear-dependence case gives a marginally consistent picture and the momentum-independent scenario fits robustly the data. We also comment on Supernova 1987a and its relevance for consideration of other neutrino species, also in relation with some scenarios that appeared in the large-extra-dimension literature.
THEORETICAL INVESTIGATION ON THE OSCILLATOR STRENGTHS OF ELECTRIC DIPOLE TRANSITIONS IN A SPHERICAL QUANTUM DOT WITH HYDROGENIC DONOR IMPURITY
Authors: RAJASHABALA S. , KANNAN R.
Published: February 2012

Dipole transition moment (DTM) of a hydrogenic donor in a spherical quantum dot of GaAs – Ga1-xAlxAs system with finite barrier confinement is obtained. The variational approach within the effective mass approximation is used as the framework for the calculation of donor ionization energy for a few excited states in quantum dot. Calculations of the DTM of an on-center shallow donor hydrogenic impurity in a GaAs quantum dot under hydrostatic pressure are presented. A linear increase in the DTM has been observed, when the dot radius increases from 2 nm to 100 nm. The important conclusions arrived at are (i) ionization energy increases and attains a maximum value occurring for a dot radius of 5 nm, after which the ionization energy decreases gradually as the dot radius increases; (ii) ionization energy for the ground state (1s) is high compared to the excited states (1p and 1d states) and (iii) a linear trend for 1p–1d transition is obtained.
THE CRITICAL ROLE OF TRUST IN MICROFINANCE SUCCESS: IDENTIFYING PROBLEMS AND SOLUTIONS
Authors: EPSTEIN MARC J. , YUTHAS KRISTI
Published: February 2012

Trust is the basis of many aspects of microfinance operations and is a critical determinant of microfinance success. Trust governs interactions within borrowing groups, between clients and loan officers and between clients and institutions. To effectively address the many strategic challenges microfinance institutions (MFIs) face, they must design control systems that address low levels of interpersonal and institutional trust in their target populations. By increasing focus on trust, MFIs can significantly improve their financial sustainability and social impact. This paper examines trust and its important role in both existing challenges and effective solutions in the microfinance industry. Informed by prior literature and field experience, a model is developed that can provide an effective foundation for scholars and MFI leaders to better understand and manage for improved microfinance success.
A P425R mutation of the proton-coupled folate transporter causing hereditary folate malabsorption produces a highly selective alteration in folate binding
Authors: Shin Daniel Sanghoon , Zhao Rongbao , Yap Enghui H. , Fiser Andras , Goldman I. David
Published: February 2012

Proton-coupled folate transporter (PCFT) mediates folate intestinal absorption and transport across the choroid plexus, processes defective in subjects with hereditary folate malabsorption (HFM). PCFT is also widely expressed in human solid tumors where it contributes to the transport of pemetrexed and other antifolates. This study defines the basis for the functional changes due to a P425R mutation detected in a subject with HFM. Among various substitutions, only positively charged mutants (P425R and P425K) lost function but in a highly selective manner. Transport of reduced folates mediated by P425R-PCFT was virtually abolished; the methotrexate influx Kt was increased fivefold (from 2 to 10 μM). In contrast, the pemetrexed influx Kt mediated by P425R-PCFT was decreased 30% compared with wild-type (WT)-PCFT. Methotrexate inhibition of pemetrexed influx was competitive with a Ki for WT-PCFT comparable to its influx Kt. However, the methotrexate influx Ki for P425R-PCFT was ∼15-fold higher than the WT-PCFT influx Kt and threefold higher than the methotrexate influx Kt for the P425R-PCFT mutant. The confirmed secondary structure and homology modeling place the P425 residue at the junction of the 6th external loop and 12th transmembrane domain, remote from the aqueous translocation pathway, a prediction confirmed by the failure to label P425C-PCFT with N-biotinylaminoethyl methanethiosulfonate-biotin and the absence of inhibition of P425C-PCFT function by water-soluble sulfhydryl reagents. Hence, despite its location, the P425R-PCFT mutation produces a conformational change that fully preserves pemetrexed binding but markedly impairs binding of methotrexate and other folates to the carrier.
Effects of high-fat diet feeding on Znt8-null mice: differences between β-cell and global knockout of Znt8
Authors: Hardy A. B. , Wijesekara N. , Genkin I. , Prentice K. J. , Bhattacharjee A. , Kong D. , Chimienti F. , Wheeler M. B.
Published: February 2012

Genomewide association studies have linked a polymorphism in the zinc transporter 8 (Znt8) gene to higher risk of developing type 2 diabetes. Znt8 is highly expressed in pancreatic β-cells where it is involved in the regulation of zinc transport into granules. However, Znt8 is also expressed in other tissues including α-cells, where its function is as yet unknown. Previous work demonstrated that mice lacking Znt8 globally were more susceptible to diet-induced obesity (Lemaire et al., Proc Natl Acad Sci USA 106: 14872–14877, 2009; Nicolson et al., Diabetes 58: 2070–2083, 2009). Therefore, the main goal of this study was to examine the physiological impact of β-cell-specific Znt8 deficiency in mice during high-fat high-calorie (HFHC) diet feeding. For these studies, we used β-cell-specific Znt8 knockout (Ins2Cre:Znt8loxP/loxP) and whole body Znt8 knockout (Cre-:Znt8−/−) mice placed on a HFHC diet for 16 wk. Ins2Cre:Znt8loxP/loxP mice on HFHC diet had similar body weights throughout the study but displayed impaired insulin biosynthesis and secretion and were glucose intolerant compared with littermate control Ins2Cre mice. In contrast, Cre-:Znt8−/−mice became remarkably obese, hyperglycemic, hyperinsulinemic, insulin resistant, and glucose intolerant compared with littermate control Cre- mice. These data show that β-cell Znt8 alone does not considerably aggravate weight gain and glucose intolerance during metabolic stress imposed by an HFHC diet. However, global loss of Znt8 is involved in exacerbating diet-induced obesity and resulting insulin resistance, and this may be due to the loss of Znt8 activity in a tissue other than the β-cell. Thus, our data suggest that Znt8 contributes to the risk of developing type 2 diabetes through β-cell- and non-β-cell-specific effects.