bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel Inhibitors of InhA Efficiently Kill
Mycobacterium tuberculosis
under Aerobic and Anaerobic Conditions
Authors: Vilchèze Catherine , Baughn Anthony D. , Tufariello JoAnn , Leung Lawrence W. , Kuo Mack , Basler Christopher F. , Alland David , Sacchettini James C. , Freundlich Joel S. , Jacobs William R.
Published: June 2011

Drug resistance in
Mycobacterium tuberculosis
has become a serious global health threat, which is now complicated by the emergence of extensively drug-resistant strains. New drugs that are active against drug-resistant tuberculosis (TB) are needed. We chose to search for new inhibitors of the enoyl-acyl carrier protein (ACP) reductase InhA, the target of the first-line TB drug isoniazid (also known as isonicotinoic acid hydrazide [INH]). A subset of a chemical library, composed of 300 compounds inhibiting
Plasmodium falciparum
enoyl reductase, was tested against
M. tuberculosis
. Four compounds were found to inhibit
M. tuberculosis
growth with MICs ranging from 1 μM to 10 μM. Testing of these compounds against
M. tuberculosis in vitro
revealed that only two compounds (CD39 and CD117) were bactericidal against drug-susceptible and drug-resistant
M. tuberculosis
. These two compounds were also bactericidal against
M. tuberculosis
incubated under anaerobic conditions. Furthermore, CD39 and CD117 exhibited increased bactericidal activity when used in combination with INH or rifampin, but CD39 was shown to be toxic to eukaryotic cells. The compounds inhibit InhA as well the fatty acid synthase type I, and CD117 was found to also inhibit tuberculostearic acid synthesis. This study provides the TB drug development community with two chemical scaffolds that are suitable for structure-activity relationship study to improve on their cytotoxicities and bactericidal activities
in vitro
and
in vivo
.
walK
and
clpP
Mutations Confer Reduced Vancomycin Susceptibility in
Staphylococcus aureus
Authors: Shoji Mitsutaka , Cui Longzhu , Iizuka Risa , Komoto Akira , Neoh Hui-min , Watanabe Yukiko , Hishinuma Tomomi , Hiramatsu Keiichi
Published: June 2011

Vancomycin-intermediate
Staphylococcus aureus
(VISA) is generated from vancomycin-susceptible
Staphylococcus aureus
by multiple spontaneous mutations. We previously reported that sequential acquisition of mutations in the two-component regulatory systems
vraSR
and
graRS
was responsible for the VISA phenotype of strain Mu50. Here we report on the identification of a novel set of regulator mutations, a deletion mutation in two-component regulatory system
walRK
(synonyms,
vicRK
and
yycFG
), and a truncating mutation in a proteolytic regulatory gene,
clpP
, responsible for the raised vancomycin resistance in a laboratory-derived VISA strain, LR5P1-V3. The contributory effect of the two mutations to vancomycin resistance was confirmed by introducing the
walK
and
clpP
mutations into the vancomycin-susceptible parent strain N315LR5P1 by a gene replacement procedure. The vancomycin MIC of N315LR5P1 was raised from 1 to 2 mg/liter by the introduction of the
walK
or
clpP
mutation, but it was raised to 4 mg/liter by the introduction of both the
walK
and
clpP
mutations. The vancomycin MIC value of the double mutant was equivalent to that of strain LR5P1-V3. Like VISA clinical strains, LR5P1-V3 and the double mutant strain LR5P1
walK
*
clpP
* exhibited a thickened cell wall, slow growth, and decreased autolytic activity. Transcriptional profiles of the mutants with gene replacements demonstrated that introduction of both the
walK
and
clpP
mutations could alter expression of dozens or hundreds of genes, including those involved in cell envelope and cellular processes, intermediary metabolism, and information pathway. A mutation prevalence study performed on 39 worldwide clinical VISA strains showed that 61.5, 7.7, 10.3, and 20.5% of VISA strains harbored mutations in
walRK
,
clpP
,
graRS
, and
vraSR
, respectively. The mutation of
walRK
was most frequently carried by VISA strains. Together, these results suggested that the mutations of
walK
and
clpP
identified in LR5P1-V3 constitute a new combination of genetic events causing vancomycin resistance in
Staphylococcus aureus
.
A Novel Cell-Associated Protection Assay Demonstrates the Ability of Certain Antibiotics To Protect Ocular Surface Cell Lines from Subsequent Clinical
Staphylococcus aureus
Challenge
Authors: Wingard J. B. , Romanowski E. G. , Kowalski R. P. , Mah F. S. , Ling Y. , Bilonick R. A. , Shanks R. M. Q.
Published: June 2011

In vivo
effectiveness of topical antibiotics may depend on their ability to associate with epithelial cells to provide continued protection, but this contribution is not measured by standard antibiotic susceptibility tests. We report a new
in vitro
method that measures the ability of test antibiotics azithromycin (AZM), erythromycin (ERY), tetracycline (TET), and bacitracin (BAC) to associate with mammalian cells and to protect these cells from destruction by bacteria. Mammalian cell lines were grown to confluence using antibiotic-free medium and then incubated in medium containing a single antibiotic (0 to 512 μg/ml). After incubation, the cells were challenged with
Staphylococcus aureus
ocular isolates, without antibiotics added to the culture medium. Epithelial cell layer integrity was assessed by gentian violet staining, and the minimum cell layer protective concentration (MCPC) of an antibiotic sufficient to protect the mammalian cells from
S. aureus
was determined. Staining was also quantified and analyzed. Bacterial viability was determined by culture turbidity and growth on agar plates. Preincubation of Chang and human corneal limbal epithelial cells with AZM, ERY, and TET at ≥64 μg/ml provided protection against AZM-susceptible
S. aureus
strains, with increasing protection at higher concentrations. TET toxicity was demonstrated at >64 μg/ml, whereas AZM displayed toxicity to one cell line at 512 μg/ml. BAC failed to show consistent protection at any dose, despite bacterial susceptibility to BAC as determined by traditional antibiotic susceptibility testing. A range of antibiotic effectiveness was displayed in this cell association assay, providing data that may be considered in addition to traditional testing when determining therapeutic dosing regimens.
Genetic Context and Structural Diversity of Class 1 Integrons from Human Commensal Bacteria in a Hospital Intensive Care Unit
Authors: Betteridge Thu , Partridge Sally R. , Iredell Jonathan R. , Stokes H. W.
Published: June 2011

Most surveys for class 1 integrons are at least partly predicated on PCR screening that targets integron conserved regions. However, class 1 integrons are structurally diverse, so dependence on conserved regions may lead to missing clinically relevant examples of class 1 integrons. Here, we surveyed a commensal population of bacteria from patients in an intensive care unit to identify class 1 integrons irrespective of their structure or genetic context. We identified several examples of class 1 integrons linked to complete Tn
402
-like or Tn
402
hybrid transposition modules and diverse insertion points with respect to the inverted repeat IRi boundary. The diversity and abundance of class 1 integrons identified are such that many novel elements seen here would not have been identified by commonly used methods, and they revealed an additional level of complexity.
PrsW Is Required for Colonization, Resistance to Antimicrobial Peptides, and Expression of Extracytoplasmic Function σ Factors in Clostridium difficile
Authors: Ho Theresa D. , Ellermeier Craig D.
Published: June 2011

Clostridium difficile
is an anaerobic, Gram-positive, spore-forming, opportunistic pathogen that is the most common cause of hospital-acquired infectious diarrhea. In numerous pathogens, stress response mechanisms are required for survival within the host. Extracytoplasmic function (ECF) σ factors are a major family of signal transduction systems, which sense and respond to extracellular stresses. We have identified three
C. difficile
ECF σ factors. These ECF σ factors, CsfT, CsfU, and CsfV, induce their own expressions and are negatively regulated by their cognate anti-σ factors, RsiT, RsiU, and RsiV, respectively. The levels of expression of these ECF σ factors increase following exposure to the antimicrobial peptides bacitracin and/or lysozyme. The expressions of many ECF σ factors are controlled by site 1 and site 2 proteases, which cleave anti-σ factors. Using a retargeted group II intron, we generated a
C. difficile
mutation in
prsW
, a putative site 1 protease. The
C. difficile prsW
mutant exhibited decreased levels of expression of CsfT and CsfU but not of CsfV. When expressed in a heterologous host,
C. difficile
PrsW was able to induce the degradation of RsiT but not of RsiU. When the
prsW
mutant was tested in competition assays against its isogenic parent in the hamster model of
C. difficile
infection, we found that the
prsW
mutant was 30-fold less virulent than the wild type. The
prsW
mutant was also significantly more sensitive to bacitracin and lysozyme than the wild type in
in vitro
competition assays. Taken together, these data suggest that PrsW likely regulates the activation of the ECF σ factor CsfT in
C. difficile
and controls the resistance of
C. difficile
to antimicrobial peptides that are important for survival in the host.
CD1d-Independent Activation of Invariant Natural Killer T Cells by Staphylococcal Enterotoxin B through Major Histocompatibility Complex Class II/T Cell Receptor Interaction Results in Acute Lung Injury
Authors: Rieder Sadiye Amcaoglu , Nagarkatti Prakash , Nagarkatti Mitzi
Published: June 2011

There are two important mechanisms of activation of invariant natural killer T cells (iNKT cells) by microbes: direct activation of the invariant T-cell receptor (TCR) by microbial glycolipids presented by CD1d and indirect activation, mediated by the responses of antigen-presenting cells to microbes. In this study, we provide evidence for a novel CD1d-independent direct activation of iNKT cells involving a microbial protein superantigen presented in the context of major histocompatibility complex class II (MHC-II), which plays a critical role in pathogenesis, thereby redefining the role of iNKT cells. Intranasal exposure to staphylococcal enterotoxin B (SEB) in C57BL/6 wild-type mice caused acute lung injury (ALI) characterized by vascular leak, cytokine storm, and infiltration of mononuclear cells in the lungs. In contrast, the vascular leak and inflammation were decreased by ∼50% in NKT cell-deficient Jα18−/−and CD1d−/−mice following SEB exposure, which was reversed following adoptive transfer of iNKT cells into CD1d−/−mice.In vitro, SEB could directly stimulate iNKT cells in a CD1d-independent manner via MHC-II/TCR interaction, specifically involving Vβ8. These studies not only demonstrate that iNKT cells can be activated directly by a bacterial protein superantigen independent of CD1d but also indicate that in addition to the conventional T cells, iNKT cells play a critical role in SEB-mediated ALI.
Migratory Activation of Primary Cortical Microglia upon Infection with Toxoplasma gondii
Authors: Dellacasa-Lindberg Isabel , Fuks Jonas M. , Arrighi Romanico B. G. , Lambert Henrik , Wallin Robert P. A. , Chambers Benedict J. , Barragan Antonio
Published: June 2011

Disseminated toxoplasmosis in the central nervous system (CNS) is often accompanied by a lethal outcome. Studies with murine models of infection have focused on the role of systemic immunity in control of toxoplasmic encephalitis, while knowledge remains limited on the contributions of resident cells with immune functions in the CNS. In this study, the role of glial cells was addressed in the setting of recrudescent
Toxoplasma
infection in mice. Activated astrocytes and microglia were observed in the close vicinity of foci with replicating parasites
in situ
in the brain parenchyma.
Toxoplasma gondii
tachyzoites were allowed to infect primary microglia and astrocytes
in vitro
. Microglia were permissive to parasite replication, and infected microglia readily transmigrated across transwell membranes and cell monolayers. Thus, infected microglia, but not astrocytes, exhibited a hypermotility phenotype reminiscent of that recently described for infected dendritic cells. In contrast to gamma interferon-activated microglia,
Toxoplasma
-infected microglia did not upregulate major histocompatibility complex (MHC) class II molecules and the costimulatory molecule CD86. Yet
Toxoplasma
-infected microglia and astrocytes exhibited increased sensitivity to T cell-mediated killing, leading to rapid parasite transfer to effector T cells
in vitro
. We hypothesize that glial cells and T cells, besides their role in triggering antiparasite immunity, may also act as “Trojan horses,” paradoxically facilitating dissemination of
Toxoplasma
within the CNS. To our knowledge, this constitutes the first report of migratory activation of a resident CNS cell by an intracellular parasite.
Oral Exposure to Trypanosoma cruzi Elicits a Systemic CD8+T Cell Response and Protection against Heterotopic Challenge
Authors: Collins Matthew H. , Craft Julie M. , Bustamante Juan M. , Tarleton Rick L.
Published: June 2011

Trypanosoma cruziinfects millions of people in Latin America and often leads to the development of Chagas disease.T. cruziinfection can be acquired at or near the bite site of the triatomine vector, butper osinfection is also a well-documented mode of transmission, as evidenced by recent microepidemics of acute Chagas disease attributed to the consumption of parasite-contaminated foods and liquids. It would also be convenient to deliver vaccines forT. cruziby the oral route, particularly live parasite vaccines intended for the immunization of reservoir hosts. For these reasons, we were interested in better understanding immunity toT. cruzifollowing oral infection or oral vaccination, knowing that the route of infection and site of antigen encounter can have substantial effects on the ensuing immune response. Here, we show that the route of infection does not alter the ability ofT. cruzito establish infection in muscle tissue nor does it impair the generation of a robust CD8+T cell response. Importantly, oral vaccination with attenuated parasites provides protection against wild-type (WT)T. cruzichallenge. These results strongly support the development of whole-organism-based vaccines targeting reservoir species as a means to alleviate the burden of Chagas disease in affected regions.
Oligopeptide Permease A5 Modulates Vertebrate Host-Specific Adaptation of Borrelia burgdorferi
Authors: Raju B. V. Subba , Esteve-Gassent Maria D. , Karna S. L. Rajasekhar , Miller Christine L. , Van Laar Tricia A. , Seshu J.
Published: June 2011

Borrelia burgdorferi
, the agent of Lyme disease, undergoes rapid adaptive gene expression in response to signals unique to its arthropod vector or vertebrate hosts. Among the upregulated genes under vertebrate host conditions is one of the five annotated homologs of oligopeptide permease A (OppA5, BBA34). A mutant lacking
oppA5
was constructed in an lp25-deficient isolate of
B. burgdorferi
strain B31, and the minimal regions of infectivity were restored via a shuttle vector pBBE22 with or without an intact copy of
bba34
. Immunoblot analysis of the
bba34
mutant revealed a reduction in the levels of RpoS, BosR, and CsrA
Bb
with a concomitant reduction in the levels of OspC, DbpA, BBK32, and BBA64. There were no changes in the levels of OspA, NapA, P66, and three other OppA orthologs. Quantitative transcriptional analysis correlated with the changes in the protein levels. However, the
bba34
mutant displayed comparable infectivities in the C3H/HeN mice and the wild-type strain, despite the reduction in several pathogenesis-related proteins. Supplementation of the growth medium with increased levels of select components, notably sodium acetate and sodium bicarbonate, restored the levels of several proteins in the
bba34
mutant to wild-type levels. We speculate that the transport of acetate appears to contribute to the accumulation of key metabolites, like acetyl phosphate, that facilitate the adaptation of
B. burgdorferi
to the vertebrate host by the activation of the Rrp2-RpoN-RpoS pathway. These studies underscore the importance of solute transport to host-specific adaptation of
B. burgdorferi
.
Lack of Association between theTlr4(Lpsd/Lpsd) Genotype and Increased Susceptibility to Escherichia coli Bladder Infections in Female C3H/HeJ Mice
Authors: Suhs Kaleigh A. , Marthaler Brodie R. , Welch Rodney A. , Hopkins Walter J.
Published: June 2011

Toll-like receptor 4 is thought to have a primary role in host defense againstEscherichia colibladder colonization, based on mouse models of urinary tract infection using C3H/HeJ female mice. This strain carries a point mutation in theTlr4gene, which renders the mice unresponsive to lipopolysaccharide (LPS) and thus limits the bladder inflammatory response and infection resolution. The importance ofTlr4as the sole genetic determinant of resistance or susceptibility can be questioned, however, by the observation that C3H/HeOuJ female mice with a functional Tlr4 do not effectively resolveE. colibladder infections. The present study further examined this inconsistency by investigating the association ofTlr4 LpsdandLpsnalleles with bladder infection susceptibility by using genetic crosses of C3H/HeJ mice withTlr4(Lpsn/Lpsn) or (Lpsn/Lpsd) mice. Heterozygous offspring of C3H/HeJ (Lpsd/Lpsd) × BALB/cAnN (Lpsn/Lpsn) mice successfully resolved bladder infections induced by a uropathogenicE. colistrain, while heterozygous mice from a C3H/HeJ (Lpsd/Lpsd) × C3H/HeOuJ (Lpsn/Lpsn) cross had severe infections. A backcross of C3H/HeJ (Lpsd/Lpsd) with (BALB/cAnN × C3H/HeJ)F1(Lpsn/Lpsd) produced mice that were either resistant or susceptible toE. colibladder infections and hadLpsd/LpsdorLpsn/LpsdTlr4genotypes. TheLpsd/LpsdorLpsn/Lpsdgenotypes were present in individual mice with unresolved bladder infections, and theLpsd/Lpsdgenotype was found in infection-resistant mice. These results indicate that at least one gene other thanTlr4strongly influences susceptibility toE. colibladder infections in C3H/HeJ mice.

IMPORTANCEWe have previously demonstrated that mouse strains with either a functional or nonfunctional Tlr4 were not able to resolve inducedEscherichia colibladder infections and that a chromosomal site distinct fromTlr4was associated with an inability to resolve bladder infections in C3H/HeJ mice. The present study has further investigated the relevance of Tlr4 in bladder infection resolution by defining theTlr4alleles present in offspring of genetic crosses of C3H/HeJ mice with infection-resistant and -susceptible inbred strains. The results of these experiments showed that mice with a normal Tlr4 on different genetic backgrounds were not able to clearE. colibladder infections and that animals with a defective Tlr4 could successfully resolve infections. These results strongly imply the presence of a gene other than inTlr4as an important genetic determinant of infection resistance/susceptibility in C3H/HeJ and other inbred mouse strains used in mouse models of infectious diseases.
The role of physical activity on cardiometabolic risk in adult greek women
Authors: Papadopoulou EE , Kontopoulou K , Kouidi E , Psirropoulos D , Deligiannis A
Published: June 2011

Introduction

Cardiovascular disease (CVD) is the leading cause of death in Western populations. In clinical practice, the goal is to identify high-risk individuals, since global CVD risk information may contribute to CVD prevention. Therefore, it is important to take into account the metabolic syndrome-related CVD risk, as well as the risk posed by traditional CVD risk factors. Several studies have shown that physical inactivity is an independent risk factor for CVD, although it is not included in the traditional cardiometabolic risk factors. Limited information exists about the prevalence of cardiometabolic risk factors, the role of physical activity on them and the burden of CVD in the adult female Greek population.

Purpose

The purpose of this study was to examine the effects of physical activity on the cardiometabolic risk factors in Greek healthy adult women.

Methods

Eighty eight women, aged 45.4±6.9 years, without any chronic disease, volunteered to participate in this study. All women were submitted to medical and anthropometric evaluation (measurement of waist circumference, weight, BMI and blood pressure) and laboratory testing for: total choles-terol, LDL, HDL, triglycerides, glucose, CRP, apoA1 and apoB (automatic biochemical analyzer, Roche). Finally, all women filled-in a questionnaire of physical activity (International Physical Activity Questionnaire-IPAQ).

Results

Of the total sample, 60.2% had a positive family his-tory of CVD, 46.6% were smokers and 9.1% alcohol drink-ers. Physical activity, based on the IPAQ, was found to have a mixed impact on the traditional cardiometabolic risk factors, by affecting mainly the levels of total cholesterol and HDL cholesterol. There was no correlation found among physical activity, blood pressure and the rest of the studied biochemical parameters in women.

Conclusions

Increased physical activity can reduce the car-diometabolic risk and improve the lipid profile in Greek adult women. Our results indicated that regular physical activity of any kind is essential for fitness and health. All health care professionals are encouraged to inform, consult and motivate individuals to be active.
The effect of ankle and knee bracing on joint stability and performance during different tasks
Authors: Richards Jim
Published: June 2011

Braces are commonly used for prevention and treatment of ankle and knee injuries by individuals who take part in sporting activities which involve challenges to the stability of joints. However, the use of ankle and knee bracing is less common in the conservative management of joint pain and pathology which is not sporting related. In all cases, the braces are attempting to provide improved stability of the joints in the coronal and transverse plane, but there has been much debate on whether bracing offers a functional or proprioceptive effect.

Much of the biomechanical testing to date has been conducted using very simple biomechanical models, which allow do not allow accurate measures of the movement and moments about the foot, ankle and knee joints in the coronal and transverse planes. From this it is safe to say that the effect of ankle and knee bracing on the coronal and transverse plane mechanics of the lower limb have not received any adequate attention in the research literature, although clinically these are the very things that such devices often claim to support and control. The importance of coronal and torsional movement and moments of the foot, ankle and knee joints has previously been identified. However, little or no work has been published to see how the torsional and coronal mechanics of the ankle and knee joints are changed during functional tasks using devices designed to control and give stability to these joints.

This workshop will consider the action of several methods of orthotic management of the ankle and knee joints on a variety of conditions by considering the research evidence. In each case, advanced methods of analysis have been used to determine the biomechanical changes and how these can be related to the clinical benefits. This will highlight not just the effects about the foot and ankle but also the effects of treating the foot and ankle on the knee, hip and pelvis. The data on a variety of methods of bracing for patellofemoral pain and ankle stability will be considered, with particular attention on the nature of the functional and proprioceptive effects of each method.
Cost-benefit analysis in occupational health: a comparison of intervention scenarios for occupational asthma and rhinitis among bakery workers
Authors: Meijster Tim , van Duuren-Stuurman Birgit , Heederik Dick , Houba Remko , Koningsveld Ernst , Warren Nicholas , Tielemans Erik
Published: June 2011

Objectives

Use of cost-benefit analysis in occupational health increases insight into the intervention strategy that maximises the cost-benefit ratio. This study presents a methodological framework identifying the most important elements of a cost-benefit analysis for occupational health settings. One of the main aims of the methodology is to evaluate cost-benefit ratios for different stakeholders (employers, employees and society). The developed methodology was applied to two intervention strategies focused on reducing respiratory diseases.

Methods

A cost-benefit framework was developed and used to set up a calculation spreadsheet containing the inputs and algorithms required to calculate the costs and benefits for all cost elements. Inputs from a large variety of sources were used to calculate total costs, total benefits, net costs and the benefit-to-costs ratio for both intervention scenarios.

Results

Implementation of a covenant intervention program resulted in a net benefit of €16 848 546 over 20 years for a population of 10 000 workers. Implementation was cost-effective for all stakeholders. For a health surveillance scenario, total benefits resulting from a decreased disease burden were estimated to be €44 659 352. The costs of the interventions could not be calculated.

Conclusion

This study provides important insights for developing effective intervention strategies in the field of occupational medicine. Use of a model based approach enables investigation of those parameters most likely to impact on the effectiveness and costs of interventions for work related diseases. Our case study highlights the importance of considering different perspectives (of employers, society and employees) in assessing and sharing the costs and benefits of interventions.
BRANE EMBEDDINGS IN ${\rm AdS}_4 \times {\mathcal{CP}}^3$
Authors: CHANDRASEKHAR B. , PANDA BINATA
Published: May 2011

We construct D-brane embeddings in [Formula: see text] by studying the consistency conditions following from the pull back of target space equations of motion. We explicitly discuss the supersymmetry preserved by these embeddings by analyzing the compatibility of kappa symmetry projections with the target space Killing spinors in each case. The embeddings correspond to AdS/dCFT dualities involving ABJM theories with a defect. We also comment on the defect CFT.
A HOLOGRAPHIC MODEL OF STRANGE METALS
Authors: LEE BUM-HOON , PANG DA-WEI , PARK CHANYONG
Published: May 2011

We give a review on our recent work arXiv:1006.0779 [hep-th] and arXiv:1006.1719 [hep-th], in which properties of holographic strange metals were investigated. The background is chosen to be anisotropic scaling solution in Einstein–Maxwell–Dilaton theory with a Liouville potential. The effects of bulk Maxwell field, an extra U(1) gauge field and probe D-branes on the DC conductivity, the DC Hall conductivity and the AC conductivity are extensively analyzed. We classify behaviors of the conductivities according to the parameter ranges in the bulk theory and characterize conditions when the holographic results can reproduce experimental data.
THERMODYNAMIC GEOMETRIC STABILITY OF QUARKONIA STATES
Authors: BELLUCCI STEFANO , CHANDRA VINOD , TIWARI BHUPENDRA NATH
Published: May 2011

We compute exact thermodynamic geometric properties of the non-Abelian quarkonium bound states from the consideration of one-loop strong coupling. From the general statistical principle, the intrinsic geometric nature of strongly coupled QCD is analyzed for the Colombic, rising and Regge rotating regimes. Without any approximation, we have obtained the nonlinear mass effect for the Bloch–Nordsieck rotating strongly coupled quarkonia. For a range of physical parameters, we show in each cases that there exists a well-defined, nondegenerate, curved, intrinsic Riemannian manifold. As the gluons become softer and softer, we find in the limit of the Bloch–Nordsieck resummation that the strong coupling obtained from the Sudakov form factor possesses exact local and global thermodynamic properties of the underlying mesons, kayons and Ds particles.
SQUARK AND GLUINO HADROPRODUCTION
Authors: BEENAKKER WIM , BRENSING SILJA , KRÄMER MICHAEL , KULESZA ANNA , LAENEN ERIC , MOTYKA LESZEK , NIESSEN IRENE
Published: May 2011

We review the theoretical status of squark and gluino hadroproduction and provide numerical predictions for all squark and gluino pair-production processes at the Tevatron and at the LHC, with a particular emphasis on proton–proton collisions at 7 TeV. Our predictions include next-to-leading order supersymmetric QCD corrections and the resummation of soft gluon emission at next-to-leading-logarithmic accuracy. We discuss the impact of the higher-order corrections on total cross-sections, and provide an estimate of the theoretical uncertainty due to scale variation and the parton distribution functions.
THE ANYON MODEL: AN EXAMPLE INSPIRED BY STRING THEORY
Authors: TALALOV S. V.
Published: May 2011

We investigate the enlarged class of open finite strings in (2+1)D space–time. The new dynamical system related to this class is constructed and quantized here. As the result, the energy spectrum of the model is defined by a simple formula [Formula: see text]; the spin [Formula: see text] is an arbitrary number here but the constants αn and cn are eigenvalues for certain spectral problems in fermionic Fock space Hψ constructed for the free 2D fermionic field.
ASYMPTOTIC QUASINORMAL MODES IN EINSTEIN–GAUSS–BONNET GRAVITY
Authors: SADEGHI J. , BANIJAMALI A. , SETARE M. R. , VAEZ H.
Published: May 2011

In this paper we consider a massive scalar field on the boundary of AdS space–time and calculate the quasinormal modes for the string inspired Einstein–Gauss–Bonnet gravity in five dimensions. We study the effects of Gauss–Bonnet parameter, temperature, scalar field's mass and momentum vector on the effective potential and quasinormal modes.
HIERARCHY IN HOŘAVA-LIKE GRAVITY
Authors: FENG YU-LEI , XU LI-XIN , WANG YU-TING
Published: May 2011

We investigate a Hořava-like gravity model in (4+1)-dimensional space–time. Differing from the original one, we put a critical exponent z to the extra space dimension, which preserves the 4-dimensional diffeomorphism. Surprisingly, we obtain a mass hierarchy [Formula: see text] in a way completely different from the Randall–Sundrum model, we also obtain an exponential factor solution with the use of Ricci-like flow. More interesting relations with AdS5/CFT4 are further demonstrated. Since AdS/CFT is a realization of holography, we conclude that the Hořava-like gravity may be also a realization of holography.
INFERRING INDIRECT COUPLING BY MEANS OF RECURRENCES
Authors: ZOU Y. , ROMANO M. C. , THIEL M. , MARWAN N. , KURTHS J.
Published: June 2011

The identification of the coupling direction from measured time series taking place in a group of interacting components is an important challenge for many experimental studies. We propose here a method to uncover the coupling configuration using recurrence properties. The approach hinges on a generalization of conditional probability of recurrence, which was originally introduced to detect and quantify even weak coupling directions between two interacting systems, to the case of multivariate time series where indirect interactions might be present. We test our method by an example of three coupled Lorenz systems. Our results confirm that the proposed method has much potential to identify indirect coupling, which is very relevant for experimental time series analysis.
BEYOND RANKED LISTS IN WEB SEARCH: AGGREGATING WEB CONTENT INTO TOPIC PAGES
Authors: BALASUBRAMANIAN NIRANJAN , CUCERZAN SILVIU
Published: June 2011

We investigate the automatic generation of topic pages as an alternative to the current Web search paradigm. Topic pages explicitly aggregate information across documents, filter redundancy, and promote diversity of topical aspects. We propose a novel framework for building rich topical aspect models and selecting diverse information from the Web. In particular, we use Web search logs to build aspect models with various degrees of specificity, and then employ these aspect models as input to a sentence selection method that identifies relevant and non-redundant sentences from the Web. Automatic and manual evaluations on biographical topics show that topic pages built by our system compare favorably to regular Web search results and to MDS-style summaries of the Web results on all metrics employed.
REDUNDANT VIRTUAL MACHINES MANAGEMENT IN VIRTUALIZED CLOUD PLATFORM
Authors: ZHANG FAN , CAO JUNWEI , CAI HONG , LIU LIANCHEN , WU CHENG
Published: June 2011

Selecting and utilizing proper virtual machines in a virtualized cloud platform to achieve high availability, throughput, reliability, as well as low cost and makespan is very important. The importance lies in the adaptive resource provisioning to satisfy variant of workloads. An Adaptive Accessing Aware Algorithm (A5) is proposed in this paper to deal with this conflicting objective optimization problem. The main strategy of A5 is selecting adaptive upper/lower bound of service capacity to decide the time for scheduling redundant virtual machines and a Pareto-front-based multi-objective optimization method to decide the number of scheduling virtual machines. We carried out experiments in simulation, which show that A5 can achieve much higher performance improvements in four different workload testing environments, compared with other three commonly used methods.
MODELING AND ANALYSIS OF EMBEDDED MULTIMEDIA APPLICATIONS USING COLORED PETRI NETS
Authors: DEY SOUMYAJIT , ROKKAM PRAVEEN , BASU ANUPAM
Published: June 2011

Embedded multimedia systems often run multiple time-constrained applications simultaneously. To meet the throughput constraints given in the specification, each application must be provided with enough resources by the underlying architecture, which is generally a multiprocessor system-on-chip (MPSoC). For this purpose, a mechanism for task binding and scheduling is required to provide each application with a timing guarantee, keeping in mind the available resources like processor(s) and memory bandwidth. Commonly, synchronous dataflow graphs (SDFGs) are used to model time-constrained multimedia applications. There are resource allocation strategies for SDFGs that help in formulating efficient techniques for calculating the throughput of a bounded and scheduled SDFG. The strategies are effective in terms of run-time and allocated resources. However, there is no unified modeling technique to simultaneously represent the application and the underlying architecture with resource allocation. This paper discusses a novel modeling technique using Colored Timed Petri Nets (CTPNs), which can be used to model the application as well as the architecture and the resource allocation. Such a representation helps in checking properties like liveness and boundedness for the application, taking into account the resource allocation and thus helping in defining satisfactory schedules for the executable tasks.
TASK ALLOCATION MODEL FOR RELIABILITY AND COST OPTIMIZATION IN DISTRIBUTED COMPUTING SYSTEM
Authors: YADAV PRADEEP KUMAR , SINGH M. P. , SHARMA KULDEEP
Published: June 2011

A Distributed Computing System (DCS) is defined as a set of processing elements interconnected by communication links. Reliability analysis of these processing elements and communication links is one of the important parameters to achieve the system efficiency. The system efficiency can be improved by making the task allocation properly in DCS. In this paper, we have presented a mathematical model, considering DCS with heterogeneous processors in order to achieve optimal cost and optimal reliability by allocating the tasks to the processors, in such a way that the allocated load on each processor is balanced. The task allocation in DCS is known as NP-hard problem even in the best conditions, and based on the present model, an efficient algorithm have been proposed to obtain optimal solutions. To design the mathematical model, execution time of the tasks on each processor as well as communication time between the tasks has been taken in the form of matrices.
REFRACTIVE INDEX AND SNELL'S LAW FOR DIPOLE-EXCHANGE SPIN WAVES IN RESTRICTED GEOMETRY
Authors: JEONG DAE-EUN , HAN DONG-SOO , KIM SANG-KOOG
Published: June 2011

We derived an analytic expression of refractive index for dipole-exchange spin waves (DESWs) in a laterally confined heterogeneous magnetic thin-film system and also derived Snell's law for DESWs by employing a dispersion relation and a specific boundary condition at a heterogeneous magnetic interface. These analytical results mimic well the macroscopic behaviors of propagation, reflection and refraction of DESWs, as obtained from micromagnetic simulations, for example, on a specific yttrium-iron-garnet ( Y 3 Fe 5 O 12) and permalloy ( Ni 80 Fe 20) interface.
TOPOLOGICAL INSULATOR AND THE DIRAC EQUATION
Authors: SHEN SHUN-QING , SHAN WEN-YU , LU HAI-ZHOU
Published: June 2011

We present a general description of topological insulators from the point of view of Dirac equations. The Z2 index for the Dirac equation is always zero, and thus the Dirac equation is topologically trivial. After the quadratic term in momentum is introduced to correct the mass term m or the band gap of the Dirac equation, i.e., m → m − Bp2, the Z2 index is modified as 1 for mB > 0 and 0 for mB < 0. For a fixed B there exists a topological quantum phase transition from a topologically trivial system to a nontrivial system when the sign of mass m changes. A series of solutions near the boundary in the modified Dirac equation is obtained, which is characteristic of topological insulator. From the solutions of the bound states and the Z2 index we establish a relation between the Dirac equation and topological insulators.
OPTIMIZATION AND INTEGRATION OF MAGNETORESISTIVE SENSORS
Authors: FREITAS PAULO P. , CARDOSO SUSANA , FERREIRA RICARDO , MARTINS VERÓNICA C. , GUEDES ANDRÉ , CARDOSO FILIPE A. , LOUREIRO JOANA , MACEDO RITA , CHAVES RUI C. , AMARAL JOSÉ
Published: June 2011

This paper addresses challenging issues related to the integration of magnetoresistive (MR) sensors in applications such as magnetic field mapping, magnetic bead detection in microfluidic channels, or biochips. Although sharing the same technological principle for detection (magnetoresistance effect), each application has unique specifications in terms of noise, sensitivity, spatial resolution, electrical robustness or geometric constraints. These differences are of high impact for manufacturing, because some strategies used for sensor optimization compromise the freedom for device architecture.
THE MANY FACES OF ORGANIC MAGNETORESISTANCE
Authors: WAGEMANS W. , JANSSEN P. , SCHELLEKENS A. J. , BLOOM F. L. , BOBBERT P. A. , KOOPMANS B.
Published: June 2011

A surprisingly large "organic magnetoresistance" (OMAR) has been found in both polymers and small molecule organic semiconductors at relatively small applied magnetic fields and at room temperature. We review recent highlights in OMAR research and discuss some of the models that have been proposed to explain the effect. In all models spin dephasing due to hyperfine fields plays an essential role. In particular we focus on the characteristic magnetic field dependence, which is generally fitted with either a Lorentzian or a so-called non-Lorentzian function. The shape is determined by both the hyperfine fields and an additional broadening due to microscopic mechanisms, as described in the models. Within the present work, a new empirical function is introduced that captures the two effects separately and converges to the earlier introduced lineshapes in specific limits. Recently it has been demonstrated that an additional feature can be observed at ultra-small magnetic fields. This effect can be easily incorporated in our empirical approach by explicitly treating the limit in which hopping of carriers is no longer slow compared to spin precession in the hyperfine fields. Our approach is used to analyze several theoretical and experimental results. It is shown that experimentally observed trends can be well-understood and important parameters can be obtained from experimental data without prior knowledge about which model applies.
PATTERNED NANOSCALE MAGNETIC TUNNEL JUNCTIONS WITH DIFFERENT GEOMETRICAL STRUCTURES
Authors: WEN Z. C. , WANG Y. , YU G. Q. , WEI H. X. , ZHANG B. S. , XU K. , HAN X. F.
Published: June 2011

In this paper, patterned nanoscale magnetic tunnel junctions (MTJs) with different geometrical structures, including nanodisk (ND), nanoellipse (NE), nanoring (NR) and nanoelliptical ring (NER) with the scale of around 100nm and ring width of around 30nm, were fabricated, respectively. The geometrical-shape dependence of magnetic field-driven and current-induced magnetization switching (CIMS) were studied in the nanoscale magnetic tunnel junctions (MTJs). The NER-MTJs showed robust magnetization switching and low critical current density of CIMS, comparing with other geometrical-shaped MTJs. This may be due to the different distribution of current-induced Oersted field in different geometrical structures, which plays an assisted role in CIMS. The present experiments indicate that NER-MTJs may be one of the promising candidates for the cells of high-density and low-consumption spintronic devices.
Fasting insulin reflects heterogeneous physiological processes: role of insulin clearance
Authors: Goodarzi Mark O. , Cui Jinrui , Chen Yii-Der I. , Hsueh Willa A. , Guo Xiuqing , Rotter Jerome I.
Published: June 2011

Several processes contribute to variation in fasting insulin concentration, including fasting glucose, insulin resistance, insulin secretion, and insulin clearance. Our goal was to determine the relative contribution of each of these insulin-related traits, plus anthropometric parameters, to fasting insulin among 470 Mexican Americans. The euglycemic hyperinsulinemic clamp yielded insulin sensitivity (M value) and metabolic clearance rate of insulin (MCRI). Acute insulin secretion was estimated by the insulinogenic index (IGI30) from the oral glucose tolerance test. Regression (univariate) and generalized estimating equations (multivariate) were used to describe the relationship of insulin-related traits to fasting insulin. Univarate analyses were used to select which traits to include in the multivariate model. In multivariate analysis, MCRI, M, BMI, waist circumference, and fasting glucose were independently associated with fasting insulin. Decreasing M and MCRI were associated with increasing fasting insulin, whereas increasing BMI, waist circumference, and fasting glucose were associated with increasing fasting insulin. Standardized coefficients allowed determination of the relative strength of each trait's association with fasting insulin in the entire cohort (strongest to weakest): MCRI (−0.35, P < 0.0001), M (−0.24, P < 0.0001), BMI (0.20, P = 0.0011), waist circumference (0.16, P = 0.021), and fasting glucose (0.11, P = 0.014). Fasting insulin is a complex phenotype influenced by several independent processes, each of which might have its own environmental and genetic determinants. One of the most associated traits was insulin clearance, which has implications for studies that have used fasting insulin as a surrogate for insulin resistance.
Fabrication of Coated-Collagen Electrospun PHBV Nanofiber Film by Plasma Method and Its Cellular Study
Authors: Ai Jafar , Heidari K Saeed , Ghorbani Fatemeh , Ejazi Fahimeh , Biazar Esmaeil , Asefnejad Azadeh , Pourshamsian Khalil , Montazeri Mohamad
Published: May 2011

Background. Tissue engineering is defined as the designing and engineering of structures to rebuild and repair a body damaged tissue. Scaffolding Poly Hydroxy Butyrate Valerate (PHBV) has shown good biocompatibility and biodegradable properties. Nanofibers have improved the performance of biomaterials, and could be considered effective. One of the important methods for designing nanofiber scaffold is the electrospinnig method. In this study, PHBV nanofibers were well designed and then, modified with the immobilized collagen via the plasma method. The samples were evaluated by ATR-FTIR, SEM, contact angle, and, finally, cell culture.Results. ATR-FTIR structural analysis showed the presence of collagen on the nanofiber surfaces. The SEM images showed the size average of nanofibers as to be about 280 nm; that increased with a collagen coating up to 300 nm. Contact angle analysis showed 67 degree for uncoated nanofibers and 56 degree for coated nanofibers. Cellular investigations (USS cells) showed better adhesion and cell growth and proliferation of coated samples than uncoated samples.Conclusions. In this work, the PHBV nanofibers with a size average about 280 nm were designed. Nanofibers were successfully coated with collagen via the plasma methods. These collagen-coated nanofibers could be used well for tissue engineering.
Studying the Properties of RF-Sputtered Nanocrystalline Tin-Doped Indium Oxide
Authors: Kashyout Abd El-Hady B. , Fathy Marwa , Soliman Moataz B.
Published: May 2011

The ceramic target of Indium tinoxide (ITO) (90% In2O3-10%SnO2) has been used to prepare transparent semiconductive thin films on glass substrate by RF magnetron sputtering at room temperature. The properties of the thin films are affected by controlling the deposition parameters, namely, RF power values and deposition times. The structure, morphology, optical and electrical properties of the thin films are investigated using X-ray diffraction (XRD), field emission scanning electron microscope (FESEM), atomic force microscope (AFM), UV-Vis spectrophotometer, and four-point probe measurement. Nanoparticles of 10–20 nm are measured and confirmed using both FESEM and AFM. The main preferred orientations of the prepared thin films are (222) and (400) of the cubic ITO structure. The transparent semiconductive films have high transmittance within the visible range of values 80–90% and resistivity of about1.62×10−4 Ω⋅cm.
A Child with X-Linked Agammaglobulinemia and Enthesitis-Related Arthritis
Authors: Sukumaran Sukesh , Marzan Katherine , Shaham Bracha , Church Joseph A.
Published: June 2011

X-linked agammaglobulinemia (XLA) is a primary immune deficiency characterized by recurrent bacterial infections and profoundly depressed serum immunoglobulin levels and circulating mature B cells. We describe a 12-year-old boy with XLA and enthesitis-related arthritis (ERA). To date, there has been a paucity of reports of noninfectious inflammatory arthritis in children with XLA. This case illustrates that functional B cells and/or immunoglobulin are not required for ERA pathogenesis. In addition, this case suggests a possible link between immune deficiency, immune dysregulation, and rheumatic illness.
Standardization of Methods for Early Diagnosis and On-Site Treatment of High-Altitude Pulmonary Edema
Authors: Zhou Qiquan
Published: June 2011

High-altitude pulmonary edema (HAPE) is a life-threatening disease of high altitude that often affects nonacclimatized apparently healthy individuals who rapidly ascend to high altitude. Early detection, early diagnosis, and early treatment are essential to maintain the safety of people who ascend to high altitude, such as construction workers and tourists. In this paper, I discuss various methods and criteria that can be used for the early diagnosis and prediction of HAPE. I also discuss the preventive strategies and options for on-site treatment. My objective is to improve the understanding of HAPE and to highlight the need for prevention, early diagnosis, and early treatment of HAPE to improve the safety of individuals ascending to high altitude.