bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of Piezo-SMA Composite for Thermal Energy Harvester Under Fluctuating Temperature
Authors: Namli Onur C. , Taya Minoru
Published: February 2011

A thermal energy harvester using piezo-shape memory alloy (SMA) composite was designed. The main mechanism of such a piezo-SMA composite is the synergistic effect of piezoelectrics and SMA, which are connected in series and subjected to fluctuating temperature. Strain induced in the SMA phase immediately causes stress in the piezoelectric phase, thus, inducing charge by the direct piezoelectric effect. In order to make this problem more analytically tractable, two models were developed: simple laminated model and 3D model with Eshelby theory. The models predict the available power according to material properties and thermal fluctuation. The impedance of the system was examined with different thermal fluctuating frequencies. Experimental and predicted results are in agreement for higher frequencies, while for lower frequencies of thermal fluctuation, the prediction is not accurate due to internal loss.
Flow and Heat Transfer Over a Continuously Moving Flat Plate in a Porous Medium
Authors: Khan W. A. , Pop I.
Published: February 2011

The effects of the presence of an isotropic solid matrix and radiation on the forced convection boundary layer past a continuously moving flat plate is studied theoretically. The transformed nondimensional partial differential equations are solved numerically for some values of the governing parameters using the local nonsimilarity method. The effects of the governing parameters on both flow and heat transfer characteristics are graphed and tabulated. An interesting result of the analysis is that as the value of the radiation parameter k0 increases, a decrease in the thermal radiation’s effect occurs.
Mineral Fouling Control by Underwater Plasma Discharge in a Heat Exchanger
Authors: Yang Yong , Kim Hyoungsup , Fridman Alexander , Cho Young I.
Published: February 2011

The excessive mineral contents in water circulation systems could cause severe fouling in heat transfer equipment. The present study investigated the effect of underwater pulsed spark discharges on the mitigation of mineral fouling in a concentric counterflow heat exchanger. Artificial hard water with calcium carbonate hardness of 250 mg/L was used with velocity ranging from 0.1 m/s to 0.5 m/s and zero blowdown. Fouling resistances decreased by 50–72% for the plasma treated cases compared with the values for no-treatment cases, indicating that the pulsed spark discharge could significantly mitigate the mineral fouling on the heat exchanger surface.
A Mobile Gait Monitoring System for Abnormal Gait Diagnosis and Rehabilitation: A Pilot Study for Parkinson Disease Patients
Authors: Bae Joonbum , Kong Kyoungchul , Byl Nancy , Tomizuka Masayoshi
Published: February 2011

Conventional gait rehabilitation treatment does not provide quantitative information on abnormal gait kinematics, and the match of the intervention strategy to the underlying clinical presentation may be limited by clinical expertise and experience. Also the effect of rehabilitation treatment may be reduced as the rehabilitation treatment is achieved only in a clinical setting. In this paper, a mobile gait monitoring system (MGMS) is proposed for the diagnosis of abnormal gait and rehabilitation. The proposed MGMS consists of Smart Shoes and a microsignal processor with a touch screen display. It monitors patients’ gait by observing the ground reaction force (GRF) and the center of GRF, and analyzes the gait abnormality. Since visual feedback about patients’ GRFs and normal GRF patterns are provided by the MGMS, patients can practice the rehabilitation treatment by trying to follow the normal GRF patterns without restriction of time and place. The gait abnormality proposed in this paper is defined by the deviation between the patient’s GRFs and normal GRF patterns, which are constructed as GRF bands. The effectiveness of the proposed gait analysis methods with the MGMS has been verified by preliminary trials with patients suffering from gait disorders.
To Be or Not to Be a T
reg
Cell: Lineage Decisions Controlled by Epigenetic Mechanisms
Authors: Toker Aras , Huehn Jochen
Published: February 2011

Differentiation of natural regulatory T cells is restricted by the SUMO ligase PIAS1.
MALT Lymphomagenesis Revisited
Authors: Mueller Kristen L.
Published: February 2011

An oncogenic fusion protein promotes lymphomagenesis by activating a noncanonical signaling pathway.
So Hungry I Could Eat Myself
Authors: Ray L. Bryan
Published: February 2011

A protein kinase links energy stores to control of autophagy.
Parasite Replication Trigger
Authors: Hurtley Stella M.
Published: February 2011

Membrane proteins govern a change from invasion to replication of an intracellular parasite.
Positive Impact of HIV-1
gag
Cleavage Site Mutations on the Virological Response to Darunavir Boosted with Ritonavir
Authors: Larrouy Lucile , Lambert-Niclot Sidonie , Charpentier Charlotte , Fourati Slim , Visseaux Benoit , Soulié Cathia , Wirden Marc , Katlama Christine , Yeni Patrick , Brun-Vézinet Françoise , Calvez Vincent , Marcelin Anne-Geneviève , Descamps Diane
Published: February 2011

We assessed the roles of baseline
gag
and
gag-pol
cleavage site mutations (CSM) on the virological outcome of a darunavir-based regimen in highly antiretroviral-experienced patients. We showed the association, in multivariate analysis, between the A431V
gag
CSM and the virological response, defined as a reduction in plasma HIV-1 RNA to <50 copies/ml at month 3 (
P
= 0.028). Our results suggest that a specific
gag
CSM might have a role on protease inhibitor susceptibility in an inhibitor-specific manner.
Use of Pharmacokinetic and Pharmacodynamic Principles To Determine Optimal Administration of Daptomycin in Patients Receiving Standardized Thrice-Weekly Hemodialysis
Authors: Patel Nimish , Cardone Katie , Grabe Darren W. , Meola Shari , Hoy Christopher , Manley Harold , Drusano George L. , Lodise Thomas P.
Published: February 2011

This study identified optimal daptomycin dosing for patients receiving thrice-weekly hemodialysis (HD). Twelve adult patients on HD received daptomycin at 6 mg/kg of body weight intravenously (i.v.) one time; plasma and dialysate samples were collected over 3 days. A 2-compartment model with separate HD and non-HD clearance terms was fit to the data. A series of 9,999-subject Monte Carlo simulations (MCS) was performed to identify HD dosing schemes providing efficacy and toxicity profiles comparable to those obtained for MCS employing the daptomycin population pharmacokinetic (PK) model derived from patients in the
Staphylococcus aureus
bacteremia-infective endocarditis (SAB-IE) study. For efficacy, we selected the HD dosing scheme which generated an area-under-the-curve (AUC) exposure profile comparable to that for the SAB-IE population model. For toxicity, we selected HD dosing schemes that minimized trough concentrations of ≥24.3 mg/liter. Separate HD dosing schemes were developed for each FDA-approved regimen and for two weekly interdialytic periods (48 and 72 h). Administration of the same parent daptomycin dose intra-HD and post-HD resulted in AUC, maximum concentration of drug in serum (
C
max
), and
C
min
values most comparable to those for SAB-IE simulations for the 48-hour interdialytic period. In contrast, all candidate HD dosing schemes provided AUC
48-72
values that were at least 50% lower than the SAB-IE AUC
48-72
values. Increasing the parent dose by 50% provided more comparable AUC
48-72
values while maintaining acceptable
C
min
values. Administration of the daptomycin parent dose intra-HD or post-HD was optimal for the 48-h interdialytic period. For the 72-h interdialytic period, clinicians should consider increasing the dose by 50% to achieve more comparable AUC
48-72
values.
Human Immunodeficiency Virus Type 1 Resistance or Cross-Resistance to Nonnucleoside Reverse Transcriptase Inhibitors Currently under Development as Microbicides
Authors: Selhorst Philippe , Vazquez Ana C. , Terrazas-Aranda Katty , Michiels Johan , Vereecken Katleen , Heyndrickx Leo , Weber Jan , Quiñones-Mateu Miguel E. , Ariën Kevin K. , Vanham Guido
Published: February 2011

Microbicides based on nonnucleoside reverse transcriptase inhibitors (NNRTIs) are currently being developed to protect women from HIV acquisition through sexual contact. However, the large-scale introduction of these products raises two major concerns. First, when these microbicides are used by undiagnosed HIV-positive women, they could potentially select for viral resistance, which may compromise subsequent therapeutic options. Second, NNRTI-based microbicides that are inactive against NNRTI-resistant strains might promote the selective transmission of these viruses. In order to address these concerns, drug resistance was selectedin vitroby the serial passage of three viral isolates from subtypes B and C and CRF02_AG (a circulating recombinant form) in activated peripheral blood mononuclear cells (PBMCs) under conditions of increasing concentrations of three NNRTIs (i.e., TMC120, UC781, and MIV-160) that are currently being developed as candidate microbicides. TMC120 and MIV-160 displayed a high genetic barrier to resistance development, whereas resistance to UC781 emerged rapidly, similarly to efavirenz and nevirapine. Phenotypically, the selected viruses appeared to be highly cross-resistant to current first-line therapeutic NNRTIs (i.e., delavirdine, nevirapine, and efavirenz), although they retained some susceptibility to the more recently developed NNRTIs lersivirine and etravirine. The ability of UC781, TMC120, and MIV-160 to inhibit thein vitro-selected NNRTI-resistant viruses was also limited, although residual activity could be observed for the candidate microbicide NNRTI MIV-170. Interestingly, only four p2/p7/p1/p6/PR/RT/INT recombinant NNRTI-resistant viruses (i.e., TMC120-resistant VI829, EFV-resistant VI829, MIV-160-resistant VI829, and EFV-resistant MP568) showed impairments in replicative fitness. Overall, thesein vitroanalyses demonstrate that due to potential cross-resistance, the large-scale introduction of single-NNRTI-based microbicides should be considered with caution.
Pharmacokinetics of Solithromycin (CEM-101) after Single or Multiple Oral Doses and Effects of Food on Single-Dose Bioavailability in Healthy Adult Subjects
Authors: Still J. Gordon , Schranz Jennifer , Degenhardt Thorsten P. , Scott Drusilla , Fernandes Prabhavathi , Gutierrez Maria J. , Clark Kay
Published: February 2011

The pharmacokinetics of orally administered solithromycin (CEM-101), a novel fluoroketolide, were evaluated in healthy subjects in three phase 1 studies. In two randomized, double-blinded, placebo-controlled studies, escalating single oral doses of solithromycin (50 to 1,600 mg) or seven oral daily doses (200 to 600 mg) of solithromycin were administered. A third study evaluated the effects of food on the bioavailability of single oral doses (400 mg) of solithromycin. Following single doses, the median time to peak concentration (
T
max
) ranged from 1.5 h to 6 h. The mean maximum measured plasma concentration (
C
max
) ranged from 0.0223 μg/ml to 19.647 μg/ml, and the area under the concentration-versus-time curve from time zero to time
t
(AUC
0–

t

) ranged from 0.0402 μg · h/ml to 28.599 μg · h/ml. There was no effect of high-fat food on the oral bioavailability of solithromycin. In the multiple-dose study, after 7 days, the mean maximum measured plasma solithromycin concentration at steady-state (
C
max,ss
) ranged from 0.248 to 1.50 μg/ml, and the area under the concentration-versus-time curve over the final dosing interval (AUC
τ
) ranged from 2.310 to 18.41 μg · h/ml. These values indicate a greater than proportional increase in exposure at 200 and 400 mg but a proportional exposure at 600 mg. Median
T
max
values remained constant between day 1 and day 7. Moderate accumulation ratios of solithromycin were observed after 7 days of dosing. All dose regimens of solithromycin were well tolerated, and no discontinuations due to an adverse event occurred. The human pharmacokinetic profile and tolerability of solithromycin, combined with its
in vitro
potency and efficacy in animal models against a broad spectrum of pathogens, support further development of solithromycin.
Evaluation of Mitochondrial Toxicity in Marmota himalayana Treated with Metacavir, a Novel 2′,3′-Dideoxyguanosine Prodrug for Treatment of Hepatitis B Virus
Authors: Zhang Pinghu , Zhang Luyong , Jiang Zhenzhou , Xiong Yating , Chen Hongkui , Tao Yuanqing , Hu Maozhi , Li Zhan
Published: February 2011

Metacavir (PNA) is a novel synthetic nucleoside analogue for the treatment of hepatitis B virus (HBV). Our recent studies showed that PNA, a prodrug of 2′,3′-dideoxyguanosine (ddG), exhibited lower mitochondrial toxicity in long-term cultures of HepG2 cells. In the current study, we examined the long-term effects of PNA on mitochondrial toxicity in
Marmota himalayana
(Himalayan marmot). Himalayan marmots were treated daily with oral PNA (50 or 100 mg/kg), ziduvidine (AZT) (100 mg/kg), or water (control) for 90 days. PNA treatment did not alter the body weight or plasma lactate acid level. In livers from the animals treated with PNA at 100 mg/kg/day, histopathology showed mild steatosis or small focal liver cell necrosis. Electron microscopy also showed minor proliferation and partial mitochondrial swelling with crista reduction. Measurement of respiratory chain complex enzyme activity and mitochondrial DNA (mtDNA) content revealed no significant differences in skeletal muscle, liver, and kidney tissues between animals treated with PNA and controls. In contrast, in Himalayan marmots treated with AZT we observed delayed toxicity, including lactic acidosis, severe hepatic steatosis, obvious mitochondrial damage, and significant decreases in respiratory chain complex enzyme activity and mtDNA content. This is similar to the delayed toxicity syndrome observed previously in animals and humans. In summary, PNA treatment did not alter mitochondrial enzyme activity or mtDNA content. This suggests that PNA could pose a very low risk for adverse mitochondrion-related effects. However, long-term hepatotoxic effects of PNA were observed, and this indicates a need for continued monitoring of PNA-associated hepatotoxicity in clinical trials.
Association of Thymidylate Synthase Gene Polymorphisms with Stavudine Triphosphate Intracellular Levels and Lipodystrophy
Authors: Domingo Pere , Cabeza M. Carmen , Pruvost Alain , Torres Ferran , Salazar Juliana , del Mar Gutierrez M. , Mateo M. Gracia , Fontanet Angels , Fernandez Irene , Domingo Joan C. , Villarroya Francesc , Vidal Francesc , Baiget Montserrat
Published: February 2011

The antiviral activity and toxicity of stavudine (d4T) depend on its triphosphate metabolite, stavudine triphosphate (d4T-TP). Therefore, modifications in intracellular levels of d4T-TP may change the toxicity profile of stavudine. d4T-TP intracellular levels in peripheral blood mononuclear cells were determined with a prominence liquid chromatograph connected to a triple-quadruple mass spectrometer. Polymorphisms in the thymidylate synthase (TS), methylenetetrahydrofolate reductase (MTHFR), dihydrofolate reductase (DHFR), reduced folate carrier 1 (RFC1; SLC19A1), and cyclin D1 (CCND1) genes were determined by direct sequencing using an ABI Prism 3100 genetic analyzer or Fluidigm's Biomark system. The Mann-Whitney test, rank analysis of variance (with Bonferroni's adjustedpost hoccomparisons), and logistic regression were used for the inferential analyses. Thirty-three stavudine-treated patients were enrolled in this cross-sectional study. d4T-TP intracellular levels were 11.50 fmol/106cells (interquartile range [IQR] = 8.12 to 13.87 fmol/106cells) in patients with a high-expression TS genotype (2/3G, 3C/3G, and 3G/3G), whereas in those with a low-expression TS genotype (2/2, 2/3C, and 3C/3C), they were 21.40 fmol/106cells (IQR = 18.90 to 27.0 fmol/106cells) (P< 0.0001). Polymorphisms in the MTHFR, DHFR, RFC1, and CCND1 genes did not influence the intracellular concentration of d4T-TP. d4T-TP levels were independently associated with the TS genotype (low versus high expression; odds ratio [OR] = 86.22; 95% confidence interval [CI] = 8.48 to nonestimable;P= 0.0023). The low-expression TS genotype was associated with the development of HIV/highly active antiretroviral therapy-associated lypodystrophy syndrome (HALS) (OR = 14.0; 95% CI = 2.09 to 108.0;P= 0.0032). Our preliminary data show that polymorphisms in the thymidylate synthase gene are strongly associated with d4T-TP intracellular levels and with development of HALS.
Further Characterization of
Bacillus subtilis
Antibiotic Biosensors and Their Use for Antibacterial Mode-of-Action Studies
Authors: Mariner Katherine R. , Ooi Nicola , Roebuck Deborah , O'Neill Alex J. , Chopra Ian
Published: February 2011

We further examined the usefulness of previously reported
Bacillus subtilis
biosensors for antibacterial mode-of-action studies. The biosensors could not detect the tRNA synthetase inhibitors mupirocin, indolmycin, and borrelidin, some inhibitors of peptidoglycan synthesis, and most membrane-damaging agents. However, the biosensors confirmed the modes of action of several RNA polymerase inhibitors and DNA intercalators and provided new insights into the possible modes of action of ciprofloxacin, anhydrotetracycline, corralopyronin, 8-hydroxyquinoline, and juglone.
Selective Inhibitors of Methionyl-tRNA Synthetase Have Potent Activity against Trypanosoma brucei Infection in Mice
Authors: Shibata Sayaka , Gillespie J. Robert , Kelley Angela M. , Napuli Alberto J. , Zhang Zhongsheng , Kovzun Kuzma V. , Pefley Ranae M. , Lam Jocelyn , Zucker Frank H. , Van Voorhis Wesley C. , Merritt Ethan A. , Hol Wim G. J. , Verlinde Christophe L. M. J. , Fan Erkang , Buckner Frederick S.
Published: February 2011

Human African trypanosomiasis continues to be an important public health threat in extensive regions of sub-Saharan Africa. Treatment options for infected patients are unsatisfactory due to toxicity, difficult administration regimes, and poor efficacy of available drugs. The aminoacyl-tRNA synthetases were selected as attractive drug targets due to their essential roles in protein synthesis and cell survival. Comparative sequence analysis disclosed differences between the trypanosome and mammalian methionyl-tRNA synthetases (MetRSs) that suggested opportunities for selective inhibition using drug-like molecules. Experiments using RNA interference on the single MetRS of
Trypanosoma brucei
demonstrated that this gene product was essential for normal cell growth. Small molecules (diaryl diamines) similar to those shown to have potent activity on prokaryotic MetRS enzymes were synthesized and observed to have inhibitory activity on the
T. brucei
MetRS (50% inhibitory concentration, <50 nM) and on bloodstream forms of
T. brucei
cultures (50% effective concentration, as low as 4 nM). Twenty-one compounds had a close correlation between enzyme binding/inhibition and
T. brucei
growth inhibition, indicating that they were likely to be acting on the intended target. The compounds had minimal effects on mammalian cell growth at 20 μM, demonstrating a wide therapeutic index. The most potent compound was tested in the murine model of trypanosomiasis and demonstrated profound parasite suppression and delayed mortality. A homology model of the
T. brucei
MetRS based on other MetRS structures was used to model binding of the lead diaryl diamine compounds. Future studies will focus on improving the pharmacological properties of the MetRS inhibitors.
Chromosome-Encoded AmpC and CTX-M Extended-Spectrum β-Lactamases in Clinical Isolates of
Proteus mirabilis
from Korea
Authors: Song Wonkeun , Kim Juwon , Bae Il Kwon , Jeong Seok Hoon , Seo Young Hee , Shin Jong Hee , Jang Sook Jin , Uh Young , Shin Jeong Hwan , Lee Mi-Kyung , Lee Kyungwon
Published: February 2011

Among 222
Proteus mirabilis
clinical isolates collected from 17 hospitals in Korea in 2008, 28 (12.6%) and 8 (3.6%) isolates exhibited extended-spectrum β-lactamase (ESBL) and AmpC phenotypes, respectively. The most common type of ESBL gene identified by PCR and sequencing experiments was
bla
CTX-M-14a
(
n
= 12). The
bla
CTX-M-90
(
n
= 4),
bla
CTX-M-15
(
n
= 3),
bla
CTX-M-12
(
n
= 3),
bla
CTX-M-2
(
n
= 2),
bla
CTX-M-14b
(
n
= 1),
bla
TEM-52
(
n
= 5), and
bla
SHV-12
(
n
= 1) genes were also detected. Eight isolates carried an AmpC β-lactamase gene, such as
bla
CMY-2
(
n
= 6) or
bla
DHA-1
(
n
= 2). All
bla
genes encoding CTX-M-1- and CTX-M-9-type enzymes and all
bla
CMY-2
genes were preceded by IS
Ecp1
-like elements. The
bla
CTX-M-2
gene found in two isolates was located on a complex class 1 integron. The
bla
DHA-1
gene was preceded by a transcriptional regulator gene and was followed by phage shock protein genes. The
bla
CTX-M
genes were located on the chromosome in 21 isolates. A plasmid location for the
bla
CTX-M
gene was found in only four isolates: the
bla
CTX-M-14a
gene was located on ∼150-kbp IncA/C plasmids in three isolates and on a ∼50-kbp IncN plasmid in one isolate. The
bla
TEM-52
gene was located on ∼50-kbp IncN plasmids in all five isolates. The AmpC β-lactamase genes were located on the chromosome in seven of eight isolates; one isolate carried the
bla
CMY-2
gene on a ∼150-kbp IncA/C plasmid. Our results show that a chromosomal location of CTX-M ESBL and AmpC β-lactamase genes in
P. mirabilis
is no longer an unusual phenomenon in hospital environments.
An Autotransporter Protein fromOrientia tsutsugamushiMediates Adherence to Nonphagocytic Host Cells
Authors: Ha Na-Young , Cho Nam-Hyuk , Kim Yeon-Sook , Choi Myung-Sik , Kim Ik-Sang
Published: February 2011

Orientia tsutsugamushi, the causative agent of scrub typhus, is an obligate intracellular pathogen whose mechanism of cellular adhesion and invasion is poorly characterized. Bioinformatic analyses of twoO. tsutsugamushigenomes revealed the presence of a group of genes that encode autotransporter proteins. In this study, we identified 10 autotransporter gene products and categorized them into five groups of orthologs (ScaA to ScaE) based on their sequence similarities. Sequence homology was highest between members of ScaC group, suggesting the functional conservation of bacterium-host interactions. ScaC was actively expressed on the surface ofO. tsutsugamushiand induced antibody responses in scrub typhus patients. Experiments using microbeads conjugated to recombinant ScaC or a surrogateEscherichia coliexpression system showed that ScaC was sufficient to mediate attachment to, but not invasion of, nonphagocytic mammalian cells. In addition, preincubation of host cells with recombinant ScaC significantly inhibited their interaction withO. tsutsugamushi. Finally, fibronectin was identified as a potential receptor for ScaC by using yeast two-hybrid screening, and this was confirmed using a glutathioneS-transferase (GST) pulldown assay. Taken together, these results demonstrate that ScaC is involved in the interaction ofO. tsutsugamushiwith mammalian host cells and suggest that ScaC may play a critical role in bacterial pathogenesis.
Healthcare scandals in the NHS: crime and punishment
Authors: Alghrani Amel , Brazier Margaret , Farrell Anne-Maree , Griffiths Danielle , Allen Neil
Published: February 2011

The Francis Report into failures of care at Mid Staffordshire NHS Foundation Trust Hospital documented a series of ‘shocking’ systematic failings in healthcare that left patients routinely neglected, humiliated and in pain as the Trust focused on cutting costs and hitting government targets. At present, the criminal law in England plays a limited role in calling healthcare professionals to account for failures in care. Normally, only if a gross error leads to death will a doctor or nurse face the prospect of prosecution. Doctors and nurses caring for patients under the Mental Health Act 1983 and the Mental Capacity Act 2005 may however be prosecuted for wilful neglect of a patient. In the light of the Francis Report, this article considers whether the criminal offence of wilful neglect should be extended to a broader healthcare setting and not confined to mental healthcare.
TOPOLOGY OF THE LATTICE OF VORTICES IN NEUTRON STARS
Authors: MONASTYRSKY M. I. , SASOROV P. V.
Published: February 2011

The structure of vortex solutions in a rotating neutron star is discussed. It is shown that the presence of additional topological charge gives rise to a significant modification of the vortex lattice.
ULTRAVIOLET AND INFRARED DIVERGENCES IN IMPLICIT REGULARIZATION: A CONSISTENT APPROACH
Authors: FARGNOLI H. G. , BAÊTA SCARPELLI A. P. , BRITO L. C. T. , HILLER B. , SAMPAIO MARCOS , NEMES M. C. , OSIPOV A. A.
Published: February 2011

Implicit Regularization is a four-dimensional regularization initially conceived to treat ultraviolet divergences. It has been successfully tested in several instances in the literature, more specifically in those where Dimensional Regularization does not apply. In the present contribution, we extend the method to handle infrared divergences as well. We show that the essential steps which rendered Implicit Regularization adequate in the case of ultraviolet divergences have their counterpart for infrared ones. Moreover, we show that a new scale appears, typically an infrared scale which is completely independent of the ultraviolet one. Examples are given.
STRANGENESS AND CHIRAL SYMMETRY BREAKING
Authors: DAHIYA HARLEEN , SHARMA NEETIKA
Published: February 2011

The implications of chiral symmetry breaking and SU(3) symmetry breaking have been studied in the chiral constituent quark model (χCQM). The role of hidden strangeness component has been investigated for the scalar matrix elements of the nucleon with an emphasis on the meson–nucleon sigma terms. The χCQM is able to give a qualitative and quantitative description of the "quark sea" generation through chiral symmetry breaking. The significant contribution of the strangeness is consistent with the recent available experimental observations.
DE SITTER SPACETIME WITH TORSION AS PHYSICAL SPACETIME IN THE VACUUM AND ISOTROPIC COSMOLOGY
Authors: MINKEVICH A. V.
Published: February 2011

Homogeneous isotropic models with two torsion functions built in the framework of the Poincaré gauge theory of gravity (PGTG) based on general expression of gravitational Lagrangian without cosmological constant are analyzed. It is shown that the physical spacetime in the vacuum in the framework of PGTG can have the structure of flat de Sitter spacetime with torsion. Some physical consequences of obtained conclusion are discussed.
AN EXPONENTIALLY SMALL μ-TERM IN STRING THEORY
Authors: HALYO EDI
Published: February 2011

We describe a mechanism that produces an exponentially small μ-term on the world-volumes of D5 branes wrapping a deformed and fibered A3 singularity. The small μ arises due to brane instanton effects which can be calculated after a geometric transition at one of the nodes of the singularity.
AMBIPOLAR DIFFUSION AND TURBULENT MAGNETIC FIELDS IN MOLECULAR CLOUDS
Authors: HOUDE MARTIN , HEZAREH TALAYEH , LI HUA-BAI , PHILLIPS THOMAS G.
Published: February 2011

We review the introduction and development of a novel method for the characterization of magnetic fields in star-forming regions. The technique is based on the comparison of spectral line profiles from coexistent neutral and ion molecular species commonly detected in molecular clouds, sites of star formation. Unlike other methods used to study magnetic fields in the cold interstellar medium, this ion/neutral technique is not based on spin interactions with the field. Instead, it relies on and takes advantage of the strong cyclotron coupling between the ions and magnetic fields, thus exposing what is probably the clearest observational manifestation of magnetic fields in the cold, weakly ionized gas that characterizes the interior of molecular clouds. We will show how recent development and modeling of the ensuing ion line narrowing effect leads to a determination of the ambipolar diffusion scale involving the turbulent component of magnetic fields in star-forming regions, as well as the strength of the ordered component of the magnetic field.
HELIUM ON NANOPATTERNED SURFACES AT FINITE TEMPERATURE
Authors: HERNANDEZ E. S. , ANCILOTTO F. , BARRANCO M. , HERNANDO A. , PI M.
Published: February 2011

We investigate the wetting behavior of helium on nanostructured alkali metal surfaces, at temperatures below and slightly above the bulk superfluidity threshold. Starting from a determination of the phase diagram of helium on semiinfinite planar Cs up to 3 K, performed within finite–range, temperature–dependent density functional theory, we examine the modifications of the isotherms introduced by an infinite array of nanocavities. We compare the hysterectic loops of helium on nonwettable Cs surfaces and on wettable Na substrates in the same temperature range.
TOWARDS DFT CALCULATIONS OF METAL CLUSTERS IN QUANTUM FLUID MATRICES
Authors: CHIN S. A. , JANECEK S. , KROTSCHECK E. , LIEBRECHT M.
Published: February 2011

This paper reports progress on the simulation of metallic clusters embedded in a quantum fluid matrix such as 4 He . In previous work we have reported progress developing a real-space density functional method. The core of the method is a diffusion algorithm that extracts the low-lying eigenfunctions of the Kohn-Sham Hamiltonian by propagating the wave functions (which are represented on a real-space grid) in imaginary time. Due to the diffusion character of the kinetic energy operator in imaginary time, algorithms developed so far are at most fourth order in the time-step. The first part of this paper discusses further progress, in particular we show that for a grid based algorithm, imaginary time propagation of any even order can be devised on the basis of multi-product splitting. The new propagation method is particularly suited for modern parallel computing environments. The second part of this paper addresses a yet unsolved problem, namely a consistent description of the interaction between helium atoms and a metallic cluster that can bridge the whole range from a single atom to a metal. Using a combination of DFT calculations to determine the response of the valence electrons, and phenomenological acounts of Pauli repulsion and short-ranged correlations that are poorly described in DFT, we show how such an interaction can be derived.
EXCHANGE-CORRELATION FUNCTIONALS FROM THE IDENTICAL-PARTICLE ORNSTEIN-ZERNIKE EQUATION: BASIC FORMULATION AND NUMERICAL ALGORITHMS
Authors: CUEVAS-SAAVEDRA ROGELIO , AYERS PAUL W.
Published: February 2011

We adapt the classical Ornstein-Zernike equation for the direct correlation function of classical theory of liquids in order to obtain a model for the exchange-correlation hole based on the electronic direct correlation function. Because we explicitly account for the identical-particle nature of electrons, our result recovers the normalization of the exchange-correlation hole. In addition, the modified direct correlation function is shorted-ranged compared to the classical formula. Functionals based on hole models require six-dimensional integration of a singular integrand to evaluate the exchange-correlation energy, and we present several strategies for efficiently evaluating the exchange-correlation integral in a numerically stable way.
FEATURES AND CATALYTIC PROPERTIES OF RhCu: A REVIEW
Authors: GONZALEZ SILVIA , SOUSA CARMEN , ILLAS FRANCESC
Published: February 2011

The study of bimetallic catalysts has scientific and technologic importance because of special catalytic activity towards several reactions. RhCu is an interesting bimetallic system due to combination of the very different catalytic activities of Rh and Cu. The catalytic activity of this bimetallic does not result from simple interpolation of the constituents. In fact, at low Cu content, the catalytic activity of RhCu is superior to that of Rh but when the Cu content is higher the activity decays. This is a curious trend which theoretical works had attempted to explain. This paper reports an overview of the most recent research works about this bimetallic system with emphasis in its especial characteristics.
GENERALIZED BOSE-EINSTEIN CONDENSATION IN SUPERCONDUCTIVITY
Authors: de LLANO MANUEL
Published: February 2011

Unification of the BCS and the Bose-Einstein condensation (BEC) theories is surveyed in detail via a generalized BEC (GBEC) finite-temperature statistical formalism. Its major difference with BCS theory is that it can be diagonalized exactly. Under specified conditions it yields the precise BCS gap equation for all temperatures as well as the precise BCS zero-temperature condensation energy for all couplings, thereby suggesting that a BCS condensate is a BE condensate in a ternary mixture of kinematically independent unpaired electrons coexisting with equally proportioned weakly-bound two-electron and two-hole Cooper pairs. Without abandoning the electron-phonon mechanism in moderately weak coupling it suffices, in principle, to reproduce the unusually high values of Tc (in units of the Fermi temperature TF) of 0.01-0.05 empirically reported in the so-called "exotic" superconductors of the Uemura plot, including cuprates, in contrast to the low values of Tc/TF ≤ 10-3 roughly reproduced by BCS theory for conventional (mostly elemental) superconductors. Replacing the characteristic phonon-exchange Debye temperature by a characteristic magnon-exchange one more than twice in size can lead to a simple interaction model associated with spin-fluctuation-mediated pairing.
KOHN ANOMALY ENERGY IN CONVENTIONAL SUPERCONDUCTORS EQUALS TWICE THE ENERGY OF THE SUPERCONDUCTING GAP: HOW AND WHY?
Authors: CHAUDHURY RANJAN , DAS MUKUNDA P.
Published: February 2011

Kohn anomaly occurs in metals as a weak but discernible kink in the phonon spectrum around 2kF arising out of screened Coulombic interaction. Over the years this has been observed in a number of normal metallic systems. As a major surprise however, the recent neutron spin-echo experiments on elemental (conventional) superconductors Pb and Nb reveal a very important and striking relation that Kohn (anomaly) energy equals twice the energy of the superconducting gap. In this paper we explore the microscopic origin of this novel phenomenon and discuss its implication to the standard model BCS Theory.
THERMAL EXPANSION OF FERROMAGNETIC SUPERCONDUCTORS: POSSIBLE APPLICATION TO UGe2
Authors: HATAYAMA NOBUKUNI , KONNO RIKIO
Published: February 2011

We investigate the temperature dependence of thermal expansion of the ferromagnetic triplet superconductors and their thermal expansion coefficients below the superconducting transition temperature of a majority spin conduction band. The free energy of the ferromagnetic superconductors derived by Linder et al. is used. The superconducting gaps in the A2 phase of 3 He and with a node in UGe 2 are considered. By applying Takahashi's method to the free energy, i.e. by taking into account the volume dependence of the free energy explicitly, the temperature dependence of the thermal expansion and the thermal expansion coefficients is studied below the superconducting transition temperature of the majority spin conduction band. We find that we have anomalies of the thermal expansion in the vicinity of the superconducting transition temperatures and that we have divergence of the thermal expansion coefficients are divergent at the superconducting transition temperatures. The Grüneisen's relation between the temperature dependence of the thermal expansion coefficients and the temperature dependence of the specific heat at low temperatures is satisfied.
INFLUENCE OF DOMAIN WALLS IN THE SUPERCONDUCTOR/FERROMAGNET PROXIMITY EFFECT
Authors: PATIÑO EDGAR J.
Published: February 2011

This paper constitutes a short review of the main experimental investigations into the subject as they were known on November 2009. The paper is also intended to be useful as an introduction to the physics of superconductivity under the presence of domain walls. First, the author briefly discusses general aspects of Superconductor/Ferromagnet (S/F) proximity effects as these can be important depending of the ferromagnet thickness. Then the so called domain wall superconductivity (DWS) and stray field effects (SFE) are clarified. The experimental evidence on each of these effects is qualitatively discussed. The difficulties on DWS experiments are outlined. The article concludes with a discussion of some outstanding issues and desirable future work.
SPIN SINGLET AND TRIPLET SUPERCONDUCTIVITY INDUCED BY CORRELATED HOPPING INTERACTIONS
Authors: PEREZ LUIS A. , MILLAN J. SAMUEL , WANG CHUMIN
Published: February 2011

In this article, we show that the Bardeen-Cooper-Schrieffer (BCS) formalism applied to a Hubbard model is capable to predict the s-, p- and d-wave superconductivity within a single theoretical scheme. This study is performed on a square lattice described by a generalized Hubbard Hamiltonian, in which correlated-hopping interactions are included in addition to the repulsive Coulombic one. Within the BCS formalism using a variable chemical potential, the superconducting ground states are determined by two coupled integral equations, whose integrand functions have main contributions around the Fermi surface. We observe the existence of a maximum critical temperature for s-, p- and d-wave superconducting channels that occur at the medium, low and high electron densities, respectively. Furthermore, the p- and d-wave superconducting specific heats show a power-law temperature dependence, instead of the exponential one for the s channel. Finally, the smallness of the anisotropic single-energy-excitation-gap minima is essential for the specific heat behavior, and this fact allows to understand the experimental data obtained from Sr2RuO4 and La2-xSrxCuO4 superconductors.
INVARIANT MEASURES OF STOCHASTIC PERTURBATIONS OF DYNAMICAL SYSTEMS USING FOURIER APPROXIMATIONS
Authors: ISLAM MD SHAFIQUL , GÓRA PAWEL
Published: February 2011

We consider dynamical system τ : [0, 1] → [0, 1] and its stochastic perturbations [Formula: see text], N ≥ 1. Using Fourier approximation, we construct a finite dimensional approximation PN to a perturbed Perron–Frobenius operator. Let [Formula: see text] be an invariant density of τ and [Formula: see text] be a fixed point of PN. We show that [Formula: see text] converges in L1 to [Formula: see text].
TOWARDS COMPOSABLE LOCATION MODELS IN UBIQUITOUS COMPUTING APPLICATIONS
Authors: LUNA ESTEBAN ROBLES , ROSSI GUSTAVO , GORDILLO SILVIA
Published: February 2011

The state of the art in location models falls short to adapt to new requirements such as composition and integration of maps. Composing and integrating maps are typical operations we want to apply when we deal with ubiquitous computing applications because they evolve permanently (i.e. to add location information of new cities, buildings, means of transport, etc.). We propose a novel approach that by abstracting some concepts such as located objects and locations, can result in more flexible models, therefore allowing dynamic composition and integration of maps. With this approach, it is also possible to combine different location representations, making applications easier to extend.
UML-BASED MODELING AND ANALYSIS OF SECURITY THREATS
Authors: KONG JUN , XU DIANXIANG , ZENG XIAOQIN
Published: February 2011

Poor design has been a major source of software security problems. Rigorous and designer-friendly methodologies for modeling and analyzing secure software are highly desirable. A formal method for software development, however, often suffers from a gap between the rigidity of the method and the informal nature of system requirements. To narrow this gap, this paper presents a UML-based framework for modeling and analyzing security threats (i.e. potential security attacks) rigorously and visually. We model the intended functions of a software application with UML statechart diagrams and the security threats with sequence diagrams, respectively. Statechart diagrams are automatically converted into a graph transformation system, which has a well-established theoretical foundation. Method invocations in a sequence diagram of a security threat are interpreted as a sequence of paired graph transformations. Therefore, the analysis of a security threat is conducted through simulating the state transitions from an initial state to a final state triggered by method invocations. In our approach, designers directly work with UML diagrams to visually model system behaviors and security threats while threats can still be rigorously analyzed based on graph transformation.
VERTICALLY AVERAGED MODELS FOR THE FREE SURFACE NON-HYDROSTATIC EULER SYSTEM: DERIVATION AND KINETIC INTERPRETATION
Authors: SAINTE-MARIE JACQUES
Published: February 2011

Starting from the Euler equations for incompressible flows, we propose an extension of the classical Saint-Venant system where the non-hydrostatic pressure terms are taken into account in the asymptotic expansion. We also derive a multilayer version of this vertically averaged Euler system. The multilayer approach allows mass exchanges between the neighboring layers. Finally we give a kinetic type interpretation for the proposed models.
BOUNDARY LAYER ENERGIES FOR NONCONVEX DISCRETE SYSTEMS
Authors: SCARDIA LUCIA , SCHLÖMERKEMPER ANJA , ZANINI CHIARA
Published: February 2011

In this work we consider a one-dimensional chain of atoms which interact through nearest and next-to-nearest neighbour interactions of Lennard–Jones type. We impose Dirichlet boundary conditions and in addition prescribe the deformation of the second and last but one atoms of the chain. This corresponds to prescribing the slope at the boundary of the discrete setting. We compute the Γ-limits of zero and first order, where the latter leads to the occurrence of boundary layer contributions to the energy. These contributions depend on whether the chain behaves elastically close to the boundary or whether there is a crack. This in turn depends on the given boundary data. We also analyse the location of fracture in dependence on the prescribed discrete slopes.
INTERFACIAL ENERGIES ON PENROSE LATTICES
Authors: BRAIDES ANDREA , SOLCI MARGHERITA
Published: February 2011

In this paper we prove a homogenization theorem for interfacial discrete energies defined on an a-periodic Penrose tiling in ℝ2. A general result on the homogenization of surface energies cannot be directly adapted to this case; the existence of the limit interfacial energy is therefore proved by showing some refined "quasi-periodic" properties of the tilings.
BRANEWORLDS AND DARK MATTER
Authors: SHAHIDI SHAHAB , SEPANGI HAMID REZA
Published: February 2011

Two problems related to dark matter are considered in the context of a braneworld model in which the confinement of gauge fields on the brane is achieved by invoking a confining potential. First, we show that the virial mass discrepancy can be addressed if the conserved geometrical term appearing in this model is considered as an energy–momentum tensor of an unknown type of matter, the so-called X-matter whose equation of state (EoS) is also obtained. Second, the galaxy rotation curves are explained by assuming an anisotropic energy–momentum tensor for the X-matter.
THEORETICAL STUDY ON THE H2 ACTIVATION BY PtO+ AND ${\rm PtO}_{2}^{+}$ IN THE GAS PHASE
Authors: TONG YONGCHUN , WANG QINGYUN , WU DONGQING , WANG YONGCHENG
Published: February 2011

Gas-phase H2 activation by PtO+ and [Formula: see text] were studied at the density functional level of theory (DFT) using the relativistic effective core potential (RECP) of Stuttgart basis sets on platinum atom and UB3LYP/6-311+G(2d,2p) level on hydrogen and oxygen atoms. Two reaction profiles corresponding to the doublet and quartet multiplicities were investigated in order to ascertain the presence of some spin inversion during the H2 reduction. The electron-transfer reactivity of the reactions were analyzed using the two-state model, and the strongly crossing behavior on the transition state (TS) area were shown. Finally, the actions of frontier molecular orbitals in minimum-energy crossing point (MECP) have been illuminated briefly. These theoretical results can act as a guide to further theoretical and experimental research. H2 activation mediated by metal oxide cations were found to be an exothermic spin-forbidden process resulting from a crossing between quartet and doublet profiles. To evaluate the spin-forbidden process in the reaction pathway, the spin-obit coupling (SOC) matrix elements are calculated at the MECP with the different potential energy surfaces (PESs) and the probability of crossing between the adiabatic potential-energy surfaces during a single pass through the avoided crossing region was described. Therefore, the intersystem crossing (ISC) at crossing points (CP) occur efficiently because of the large SOC (ca. 85.58 cm-1) involved.
COMPUTER-AIDED DESIGN OF OLED MATERIALS: A MOLECULAR MODELING APPROACH FOR OPTICAL PROPERTIES OF α-FLUORENYL OLIGOTHIOPHENES
Authors: JUNGSUTTIWONG SIRIPORN , NAMUANGRAK SUPAWADEE , PROMARAK VINICH , SUDYOADSUK TAWEESAK , VANNARAT SORNTHEP
Published: February 2011

Mono- and di-substituted α-fluorenyl oligothiophenes, FTn and FTFn (n is the number of thiophene units), have been investigated by efficient theoretical approaches, DFT and TDDFT with hybrid functional, B3LYP, and split valence plus polarization (SVP) basis set. The conjugation length was extended by increasing the number thiophene units up to pentamer (n = 1-5). According to our results, the structural and optical properties of these materials can be tuned by varying the number of thiophene units. We also reported a maximum absorption and a maximum emission of an ideal polymer which are in very good agreement with the experimental observation. It has, therefore, been demonstrated that TDDFT provides an accurate performance and can be one of the useful and affordable methods for future studies involving conjugated organic materials in OLEDs.
THE EFFECT OF VIBRATIONAL EXCITATION OF THE REACTION O(3P) + HCl → OH + Cl FOR THE 3A″ ELECTRONIC STATES
Authors: LIU HUIRONG , LIU XINGUO , ZHU TONG , SUN HAIZHU , ZHANG QINGGANG
Published: February 2011

Using the quasi-classical trajectory (QCT) method, this paper has explored the product rotational polarization for the reaction O (3 P ) + HCl → OH + Cl on the 3 A ″ potential energy surface constructed by Ramachandran B et al. (Ramachandran B et al., J. Chem. Phys.119: 9590, 2003). The distributions of product polarization P(θr),P(φr) and the generalized polarization-dependent differential cross-sections (2π/σ)(dσ00/dσt) and (2π/σ)(dσ22+/dωt) have been calculated. The results indicate that the vibrational excitation of HCl has a considerable influence on the distribution of the k-j′ correlation and the k-k′-j′ correlation.
COMPRESSED SENSING BY ITERATIVE THRESHOLDING OF GEOMETRIC WAVELETS: A COMPARING STUDY
Authors: MA JIANWEI
Published: February 2011

Recently, a new compressed-sensing (CS) theory for simultaneous sampling and compression of signals has been applied for imaging and remote sensing. The CS makes it possible for us to take super-resolution photos only using one or a few pixels rather than millions of pixels by conventional digital cameras. However, the performances of CS are related to choices of a measurement matrix and a sparse transform. In this paper, we present an experimentally comparing study for the use of different measurement matrices (e.g., random matrices, noiselet transform matrices, and scrambled block Hadamard ensemble) in encoding step and different geometric wavelets (e.g., curvelets and bandlets) in decoding step. Numerical experiments for single-pixel imaging and Fourier-domain multiple-pixel imaging indicate how to choose a suitable CS strategy to reduce the number of measurements and decoding costs.