bluuebunny/crossref_metadata_2025 huggingface dataset:
The Histidine Kinase PdhS Controls Cell Cycle Progression of the Pathogenic Alphaproteobacterium Brucella abortus
Authors: Van der Henst Charles , Beaufay François , Mignolet Johann , Didembourg Christian , Colinet Julien , Hallet Bernard , Letesson Jean-Jacques , De Bolle Xavier
Published: July 2012

Bacterial differentiation is often associated with the asymmetric localization of regulatory proteins, such as histidine kinases. PdhS is an essential and polarly localized histidine kinase in the pathogenic alphaproteobacterium
Brucella abortus
. After cell division, PdhS is asymmetrically segregated between the two sibling cells, highlighting a differentiation event. However, the function(s) of PdhS in the
B. abortus
cell cycle remains unknown. We used an original approach, the pentapeptide scanning mutagenesis method, to generate a thermosensitive allele of
pdhS
. We report that a
B. abortus
strain carrying this
pdhS
allele displays growth arrest and an altered DivK-yellow fluorescent protein (YFP) polar localization at the restrictive temperature. Moreover, the production of a nonphosphorylatable PdhS protein or truncated PdhS proteins leads to dominant-negative effects by generating morphological defects consistent with the inhibition of cell division. In addition, we have used a domain mapping approach combined with yeast two-hybrid and fluorescence microscopy methods to better characterize the unusual PdhS sensory domain. We have identified a fragment of the PdhS sensory domain required for protein-protein interaction (amino acids [aa] 210 to 434), a fragment sufficient for polar localization (aa 1 to 434), and a fragment (aa 527 to 661) whose production in
B. abortus
correlates with the generation of cell shape alterations. The data support a model in which PdhS acts as an essential regulator of cell cycle progression in
B. abortus
and contribute to a better understanding of the differentiation program inherited by the two sibling cells.
Involvement of the Global Regulator H-NS in the Survival of Escherichia coli in Stationary Phase
Authors: Chib Savita , Mahadevan Subramony
Published: July 2012

Long-term batch cultures of
Escherichia coli
grown in nutrient-rich medium accumulate mutations that provide a growth advantage in the stationary phase (GASP). We have examined the survivors of prolonged stationary phase to identify loci involved in conferring a growth advantage and show that a mutation in the
hns
gene causing reduced activity of the global regulator H-NS confers a GASP phenotype under specific conditions. The
hns-66
allele bears a point mutation within the termination codon of the H-NS open reading frame, resulting in a longer protein that is partially functional. Although isolated from a long-term stationary-phase culture of the parent carrying the
rpoS819
allele that results in reduced RpoS activity, the
hns-66
survivor showed a growth disadvantage in the early stationary phase (24 to 48 h) when competed against the parent. The
hns-66
mutant is also unstable and reverts at a high frequency in the early stationary phase by accumulating second-site suppressor mutations within the
ssrA
gene involved in targeting aberrant proteins for proteolysis. The mutant was more stable and showed a moderate growth advantage in combination with the
rpoS819
allele when competed against a 21-day-old parent. These studies show that H-NS is a target for mutations conferring fitness gain that depends on the genetic background as well as on the stage of the stationary phase.
Novel Repressor of Escherichia coli O157:H7 Motility Encoded in the Putative Fimbrial Cluster OI-1
Authors: Allison Sarah E. , Silphaduang Uma , Mascarenhas Mariola , Konczy Paulina , Quan Quyen , Karmali Mohamed , Coombes Brian K.
Published: July 2012

Escherichia coli
O157:H7 is a gastrointestinal pathogen that has become a serious public health concern, as it is associated with outbreaks and severe diseases such as hemolytic-uremic syndrome. The molecular basis of its greater virulence than that of other serotypes is not completely known. OI-1 is a putative fimbria-encoding genomic island that is found almost exclusively in O157:H7 Shiga toxin-producing
E. coli
strains and may be associated with the enhanced pathogenesis of these strains. In this study, we identified and characterized a novel repressor of flagellar synthesis encoded by OI-1. We showed that deletion of
Z0021
increased the motility of
E. coli
O157:H7, which correlated with an increase in flagellin production and enhanced assembly of flagella on the cell surface. In contrast, overexpression of
Z0021
inhibited motility. We demonstrated that Z0021 exerted its regulatory effects downstream of the transcription and translation of
flhDC
but prior to the activation of class II/III promoters. Furthermore, the master regulator of flagellar synthesis, FlhD
4
C
2
, was shown to be a high-copy suppressor of the nonmotile phenotype associated with elevated levels of Z0021—a finding consistent with Z0021-FlhD
4
C
2
being a potential regulatory complex. This work provides insight into the mechanism by which Z0021, which we have named
fmrA
, represses flagellar synthesis and is the first report of a fimbrial-operon-encoded inhibitor of motility in
E. coli
O157:H7.
The Genus Corynebacterium and Other Medically Relevant Coryneform-Like Bacteria
Authors: Bernard Kathryn
Published: July 2012

Catalase-positive Gram-positive bacilli, commonly called “diphtheroids” or “coryneform” bacteria were historically nearly always dismissed as contaminants when recovered from patients, but increasingly have been implicated as the cause of significant infections. These taxa have been underreported, and the taxa were taxonomically confusing. The mechanisms of pathogenesis, especially for newly described taxa, were rarely studied. Antibiotic susceptibility data were relatively scant. In this minireview, clinical relevance, phenotypic and genetic identification methods, matrix-assisted laser desorption ionization–time of flight (MALDI-TOF) evaluations, and antimicrobial susceptibility testing involving species in the genusCorynebacteriumand other medically relevant Gram-positive rods, collectively called coryneforms, are described.
Evaluation of Double-Disk Potentiation and Disk Potentiation Tests Using Dipicolinic Acid for Detection of Metallo-β-Lactamase-Producing Pseudomonas spp. and Acinetobacter spp
Authors: Yong Dongeun , Lee Yangsoon , Jeong Seok Hoon , Lee Kyungwon , Chong Yunsop
Published: July 2012

Accurate detection of metallo-β-lactamase (MBL)-producing
Pseudomonas
spp. and
Acinetobacter
spp. became very important with the increasing prevalence of carbapenem-nonsusceptible clinical isolates. The performance of phenotypic MBL detection methods may depend on the types of MBL and the characteristics of the isolates. A high false-positive rate is a problem with EDTA-based MBL detection methods. We evaluated the performance of double-disk potentiation tests (DDPTs) and disk potentiation tests (DPTs) with dipicolinic acid (DPA) using 44 isolates of
Pseudomonas
spp. and
Acinetobacter
spp. producing IMP-1-like, VIM-2-like, and SIM-1 type MBLs. Also, we characterized
P. aeruginosa
isolates with positive imipenem (IPM)-DPA DDPT, but negative meropenem (MEM)-DPA DDPT, and determined possibility of improving a DDPT by using MacConkey agar. Among five different DDPT methods, the IPM-DPA 250-μg method showed the highest sensitivity (97.7%) and specificity (100%). Among four DPT tests, the highest sensitivity (100%) was shown by the IPM-EDTA 1,900-μg disk method, but the specificity was very low (11.4%). Five of six
P. aeruginosa
isolates with false-negative DDPTs with MEM-DPA 250-μg disks carried
bla
IMP-6,
and the high level resistance to MEM (MIC ≥ 512 μg/ml) was reduced by the presence of phenylalanine arginine β-naphtylamide. Improvement of DDPTs was observed when MacConkey agar was used instead of Mueller-Hinton agar. In conclusion, DPA is a better MBL inhibitor than EDTA for detection of
Pseudomonas
spp. and
Acinetobacter
spp. with IMP-1-like, VIM-2-like, and SIM-1-type MBLs. In DPA DDPTs, IPM disks perform better than MEM disks when the isolates are highly resistant to MEM due to the overexpression of efflux pumps.
Galactomannan Enzymatic Immunoassay Cross-Reactivity Caused by Prototheca Species
Authors: Van den Bossche D. , De Bel A. , Hendrickx M. , De Becker A. , Jacobs R. , Naessens A. , Piérard D.
Published: July 2012

We report a reactive
Aspergillus
galactomannan enzymatic immunoassay against the serum of a patient with invasive
Prototheca zopfii
infection. Analysis of the supernatants of suspensions of
P. zopfii
and other
Prototheca
isolates revealed positive results as well. These data suggest cross-reactivity with the serum
Aspergillus
galactomannan assay in invasive protothecosis.
Eastern Chimpanzees, but Not Bonobos, Represent a Simian Immunodeficiency Virus Reservoir
Authors: Li Yingying , Ndjango Jean-Bosco , Learn Gerald H. , Ramirez Miguel A. , Keele Brandon F. , Bibollet-Ruche Frederic , Liu Weimin , Easlick Juliet L. , Decker Julie M. , Rudicell Rebecca S. , Inogwabini Bila-Isia , Ahuka-Mundeke Steve , Leendertz Fabian H. , Reynolds Vernon , Muller Martin N. , Chancellor Rebecca L. , Rundus Aaron S. , Simmons Nicole , Worobey Michael , Shaw George M. , Peeters Martine , Sharp Paul M. , Hahn Beatrice H.
Published: July 2012

Chimpanzees in west central Africa (
Pan troglodytes troglodytes
) are endemically infected with simian immunodeficiency viruses (SIVcpz
Ptt
) that have crossed the species barrier to humans and gorillas on at least five occasions, generating pandemic and nonpandemic forms of human immunodeficiency virus type 1 (HIV-1) as well as gorilla SIV (SIVgor). Chimpanzees in east Africa (
Pan troglodytes schweinfurthii
) are also infected with SIVcpz; however, their viruses (SIVcpz
Pts
) have never been found in humans. To examine whether this is due to a paucity of natural infections, we used noninvasive methods to screen wild-living eastern chimpanzees in the Democratic Republic of the Congo (DRC), Uganda, and Rwanda. We also screened bonobos (
Pan paniscus
) in the DRC, a species not previously tested for SIV in the wild. Fecal samples (
n
= 3,108) were collected at 50 field sites, tested for species and subspecies origin, and screened for SIVcpz antibodies and nucleic acids. Of 2,565 samples from eastern chimpanzees, 323 were antibody positive and 92 contained viral RNA. The antibody-positive samples represented 76 individuals from 19 field sites, all sampled north of the Congo River in an area spanning 250,000 km
2
. In this region, SIVcpz
Pts
was common and widespread, with seven field sites exhibiting infection rates of 30% or greater. The overall prevalence of SIVcpz
Pts
infection was 13.4% (95% confidence interval, 10.7% to 16.5%). In contrast, none of the 543 bonobo samples from six sites was antibody positive. All newly identified SIVcpz
Pts
strains clustered in strict accordance to their subspecies origin; however, they exhibited considerable genetic diversity, especially in protein domains known to be under strong host selection pressure. Thus, the absence of SIVcpz
Pts
zoonoses cannot be explained by an insufficient primate reservoir. Instead, greater adaptive hurdles may have prevented the successful colonization of humans by
P. t. schweinfurthii
viruses.
Human Cytomegalovirus Stimulates Monocyte-to-Macrophage Differentiation via the Temporal Regulation of Caspase 3
Authors: Chan Gary , Nogalski Maciej T. , Yurochko Andrew D.
Published: July 2012

Monocytes are primary targets for human cytomegalovirus (HCMV) infection and are proposed to be responsible for hematogenous dissemination of the virus. Biologically, monocytes have a short life span of 48 h in the circulation, a period of time during which monocytes must make a cell fate decision on whether to undergo apoptosis or differentiate into a macrophage. We have previously shown that HCMV infection stimulates monocyte-to-macrophage differentiation; however, the mechanism(s) by which HCMV-infected monocytes simultaneously navigate the 48-h “viability gate” and undergo macrophagic differentiation has remained elusive. Studies have demonstrated that the level of caspase 3 and 8 activities in monocytes may mediate the delicate balance between apoptosis and macrophage colony-stimulating factor (M-CSF)-induced myeloid differentiation. Here, we show that HCMV infection, unlike M-CSF treatment, does not induce caspase 8 activity to promote myeloid differentiation. However, HCMV infection does induce a temporal activation of caspase 3, with only a low level of active caspase 3 being observed after the 48-h viability checkpoint. Consistent with the role of a time-dependent activation of caspase 3 in promoting myeloid differentiation, the inhibition of caspase 3 blocked HCMV-induced monocyte-to-macrophage differentiation. Temporal transcriptome and functional analyses identified heat shock protein 27 (HSP27) and Mcl-1, two known regulators of caspase 3 activation, as being upregulated prior to the 48-h viability gate following HCMV infection. Using small interfering RNAs (siRNAs), we demonstrate that HCMV targets the rapid induction of HSP27 and Mcl-1, which cooperatively function to precisely control caspase 3 activity in order to allow for HCMV-infected monocytes to successfully traverse the 48-h cell fate decision checkpoint and commence macrophage maturation. Overall, this study highlights a unique regulatory mechanism employed by HCMV to tightly modulate the caspase 3 activity needed to promote myeloid differentiation, a key process in the viral dissemination and persistence strategy.
Report of two cases of a rare cause of subarachnoid hemorrhage including unusual presentation and an emerging and effective treatment option
Authors: Nyberg Eric MacKenzie , Chaudry M Imran , Turk Aquilla S , Spiotta Alejandro M , Fiorella David , Turner Raymond D
Published: July 2012

Purpose

To report two cases of a rare cause of subarachnoid hemorrhage (SAH), including unusual presentation and an emerging and effective treatment option.

Case reports

Ruptured basilar perforator artery aneurysm is a rare cause of SAH. Catheter angiography in the immediate post hemorrhage period may be unrevealing. We report two cases of ruptured basilar pontine perforator aneurysms. In one of these cases the perforator aneurysm was not apparent on the initial or the 1 week follow-up angiograms. Both patients returned for follow-up angiography 2 months later by which time aneurysmal filling and conspicuity had increased. Both patients were treated solely with two overlapping Neuroform stents. Follow-up angiograms demonstrated complete resolution of the aneurysms in both patients.

Conclusions

Rupture of aneurysms arising from basilar artery perforators is a rare cause of SAH and attention to this area should be part of an interventionist's search pattern. Aneurysms in this area may not be apparent in the immediate post rupture setting and delayed post hemorrhage angiography has a role in detecting this entity. Stent monotherapy may be effective in treating these lesions.
THE LUTTINGER LIQUID AND INTEGRABLE MODELS
Authors: SIRKER J.
Published: July 2012

Many fundamental one-dimensional lattice models such as the Heisenberg or the Hubbard model are integrable. For these microscopic models, parameters in the Luttinger liquid theory can often be fixed and parameter-free results at low energies for many physical quantities such as dynamical correlation functions obtained where exact results are still out of reach. Quantum integrable models thus provide an important testing ground for low-energy Luttinger liquid physics. They are, furthermore, also very interesting in their own right and show, for example, peculiar transport and thermalization properties. The consequences of the conservation laws leading to integrability for the structure of the low-energy effective theory have, however, not fully been explored yet. I will discuss the connection between integrability and Luttinger liquid theory here, using the anisotropic Heisenberg model as an example. In particular, I will review the methods which allow to fix free parameters in the Luttinger model with the help of the Bethe ansatz solution. As applications, parameter-free results for the susceptibility in the presence of nonmagnetic impurities, for spin transport, and for the spin-lattice relaxation rate are discussed.
BERRY PHASE AND CRITICAL BEHAVIOR OF THE XY SPIN CHAIN WITH THREE-SITE INTERACTION
Authors: LIAN HANLI
Published: July 2012

By calculating the Berry Phase (BP) of a central spin, the quantum criticality of the surrounding environment described by an XY spin chain with the three-site interaction in a transverse magnetic field is explored. The BP presents anomalous behavior along the critical region. The finite-size scaling behaviors suggest that the BP of the central spin can well capture the critical properties of the XY spin chain with the three-site interaction.
INTERCALATION OF COBALT UNDERNEATH A MONOLAYER OF GRAPHENE ON Ru(0001)
Authors: LIAO Q. , ZHANG H. J. , WU K. , LI H. Y. , BAO S. N. , HE P.
Published: July 2012

Scanning tunneling microscopy is used to study intercalation of cobalt underneath a graphene layer on Ru(0001) . Deposition of cobalt on graphene/ Ru(0001) at 873 K leads to the intercalation of cobalt between the graphene layer and the Ru(0001) substrate, and the intercalation is associated with Co diffusion at steps and defects. The morphology of graphene/ Co/Ru(0001) shows moiré pattern, as same as that of graphene/ Ru(0001) . The bright areas where Co islands exist are hcp regions of graphene/ Ru(0001) . The intercalated Co islands have a pseudomorphic structure superimposed on Ru(0001) .
EXPERIMENTAL CHARACTERIZATION AND MODELING ANALYSIS ON NPN AlGaN/GaN HBT WITH HIGH IDEALITY FACTOR IN BOTH COLLECTOR AND BASE CURRENT
Authors: TAN SHIH-WEI , LAI SHIH-WEN
Published: July 2012

Characterization and modeling analysis on both ideality factor of the collector current (η C ) and the base current (η B ) have higher than the excepted values of 1.0 and 2.0, respectively, for npn Al GaN/GaN heterojunction bipolar transistors (HBTs) have been reported. We employ the rapid thermal process annealing (RTP-annealing) to modify the base parasitical Schottky diode (called A-HBTs) after the as-deposited Ni/Au bilayers on the base layer for electrode with no annealing (called N-HBTs) to compare with each other. For a HBT operated in Gummel-plot configuration, experimental and modeling results indicate that the base parasitical Schottky diode (BPSD) causes the base current (I B ) and collector current (I C ) with high ideality factor and raise the base-emitter voltage (V BE ) to higher operation point, and therefore lead to more power consumption. Furthermore, the extended Ebers–Moll equivalent-circuit model together with the extracted device parameters provided simulated results that were in a good agreement with experimental ones.
CASIMIR FRICTION FORCE FOR MOVING HARMONIC OSCILLATORS
Authors: HØYE JOHAN S. , BREVIK IVER
Published: July 2012

Casimir friction is analyzed for a pair of dielectric particles in relative motion. We first adopt a microscopic model for harmonically oscillating particles at finite temperature T moving non-relativistically with constant velocity. We use a statistical-mechanical description where time-dependent correlations are involved. This description is physical and direct, and, in spite of its simplicity, is able to elucidate the essentials of the problem. This treatment elaborates upon, and extends, an earlier theory of ours back in 1992. The energy change ΔE turns out to be finite in general, corresponding to a finite friction force. In the limit of zero temperature the formalism yields, however, ΔE → 0, this being due to our assumption about constant velocity, meaning slowly varying coupling. For couplings varying more rapidly, there will also be a finite friction force at T = 0. As second part of our work, we consider the friction problem using time-dependent perturbation theory. The dissipation, basically a second order effect, is obtainable with the use of first order theory, the reason being the absence of cross terms due to uncorrelated phases of eigenstates. The third part of the present paper is to demonstrate explicitly the equivalence of our results with those recently obtained by Barton (2010); this being not a trivial task since the formal results are seemingly quite different from each other.
COSMIC STRINGS STABILIZED BY FERMION FLUCTUATIONS
Authors: WEIGEL HERBERT , QUANDT MARKUS , GRAHAM NOAH
Published: July 2012

We provide a thorough exposition of recent results on the quantum stabilization of cosmic strings. Stabilization occurs through the coupling to a heavy fermion doublet in a reduced version of the standard model. The study combines the vacuum polarization energy of fermion zero-point fluctuations and the binding energy of occupied energy levels, which are of the same order in a semi-classical expansion. Populating these bound states assigns a charge to the string. Strings carrying fermion charge become stable if the Higgs and gauge fields are coupled to a fermion that is less than twice as heavy as the top quark. The vacuum remains stable in the model, because neutral strings are not energetically favored. These findings suggest that extraordinarily large fermion masses or unrealistic couplings are not required to bind a cosmic string in the standard model.
ON THE ELECTROMAGNETIC VACUUM OF RANDOM MEDIA
Authors: DONAIRE MANUEL
Published: July 2012

We present a microscopical approach to the electromagnetic vacuum energy of a random medium made of non-polar molecules. We evaluate the contribution of statistical fluctuations to the average total vacuum energy. While the Lamb shift is a function of the electrical susceptibility only, the vacuum energy is generally not, except in the quasicrystalline approximation. We comment on the possibility of testing experimentally our results. We clarify why the effective medium vacuum energy (i.e., that of long-wavelengths) does not account for the total vacuum energy of a molecular dielectric. Consequently, the Lamb shift does not derive from the effective medium vacuum energy except at leading order in the molecular density.
YANG-MILLS CONDENSATES IN COSMOLOGY
Authors: GAL'TSOV D.V. , DAVYDOV E.A.
Published: July 2012

We discuss homogeneous and isotropic cosmological models driven by SU(2) gauge fields in the framework of Einstein gravity. There exists a Yang-Mills field configuration, parametrized by a single scalar function, which consists of parallel electric and magnetic fields and has the stress tensor mimicking an homogeneous and isotropic fluid. The unique SU(2) gauge theory with spontaneous symmetry breaking sharing the same property is the Yang-Mills coupled to the complex doublet Higgs, this exists only in the case of the closed universe. This model contains an intrinsic mechanism for inflation due to the Higgs potential. Our second goal is to show that a successful inflation can be achieved also within the pure Yang-Mills theory adding an appropriate theta-term.
QUANTUM BACKREACTION (CASIMIR) EFFECT WITHOUT INFINITIES: ALGEBRAIC ANALYSIS
Authors: HERDEGEN ANDRZEJ
Published: July 2012

Casimir effect, in most general terms, is the backreaction of a quantum system responding to an adiabatic change of external conditions. This backreaction is expected to be quantitatively measured by a change in the expectation value of a certain energy observable of the system. However, for this concept to be applicable, the system has to retain its identity in the process. Most prevailing tendencies in the analysis of the effect seem to ignore this question.

In general, a quantum theory is defined by an algebra of observables, whose representations by operators in a Hilbert space define concrete physical systems described by the theory. A quantum system retains its identity if both the algebra as well as its representation do not change. We discuss the resulting restrictions for admissible models of changing external conditions. These ideas are applied to quantum field models. No infinities arise, if the algebraic demands are respected.
OPTICAL PROBES OF THE QUANTUM VACUUM: THE PHOTON POLARIZATION TENSOR IN EXTERNAL FIELDS
Authors: KARBSTEIN FELIX , ROESSLER LARS , DÖBRICH BABETTE , GIES HOLGER
Published: July 2012

The photon polarization tensor is the central building block of an effective theory description of photon propagation in the quantum vacuum. It accounts for the vacuum fluctuations of the underlying theory, and in the presence of external electromagnetic fields, gives rise to such striking phenomena as vacuum birefringence and dichroism. Standard approximations of the polarization tensor are often restricted to on-the-light-cone dynamics in homogeneous electromagnetic fields, and are limited to certain momentum regimes only. We devise two different strategies to go beyond these limitations: First, we aim at obtaining novel analytical insights into the photon polarization tensor for homogeneous fields, while retaining its full momentum dependence. Second, we employ wordline numerical methods to surpass the constant-field limit.
Impact of Coumarin Dye Doping on Photovoltaic Properties of Bulk Heterojunction Device
Authors: Yamashita Kenichi , Watanabe Tomoki , Maeda Tatsuya , Yanagi Hisao
Published: July 2012

In this article, we describe the photovoltaic properties of polymer–fullerene bulk-heterojunction films doped with Coumarin dyes. Although the two kinds of dye used in this study have similar absorption bands, distinct differences in both short-circuit current density and open-circuit voltage have been observed. In particular, we found that open-circuit voltage could be enhanced by doping with Coumarin 307. This finding implies that doping with organic dyes is a potentially effective scheme for improving the open-circuit voltage as well as the short-circuit current of bulk heterojunction devices.
All-Optical Switching in Nonlinear Multimode Interference Couplers
Authors: Ogusu Kazuhiko
Published: July 2012

We numerically investigate all-optical switching in multimode interference (MMI) couplers made of self-focusing Kerr media using the beam propagation method. In numerical modeling, a 2×2 MMI coupler is treated to operate as a nearly two-mode interference (TMI) coupler. Although this coupler operates as a conventional directional coupler in a linear case, it exhibits multiple switching in a nonlinear case unlike in the case of a nonlinear directional coupler, depending on the input power. In order to obtain guidelines for designing nonlinear TMI couplers and their application, the transmittance and switching properties are numerically analyzed for different coupler lengths and input powers. The field evolution in the nonlinear multimode waveguide constituting the TMI coupler is also presented for deeper understanding of the operation principle. The results obtained will be useful in developing novel all-optical devices.
Optimization of Rubbing Angle in a Bistable 90°-Twisted Liquid Crystal Cell for Low Voltage Operation
Authors: Jo Min-Gyeong , Song Dong Han , Lee Ji-Hoon , Yoon Tae-Hoon
Published: July 2012

We studied the bistable switching behavior of a 90°-twisted liquid crystal cell that has two stable states: clockwise and counterclockwise twists. Switching between the two states can be made by applying a vertical or an in-plane electric field. We found the optimum rubbing angle for low voltage operation of a bistable twisted-nematic cell.
Study on Resist Performance of Polymer-Bound and Polymer-Blended Photo-Acid Generators
Authors: Tuan Dang Nguyen , Yamamoto Hiroki , Tagawa Seiichi
Published: July 2012

In the fabrication beyond a 16 nm node, the uniform distribution of acid generators in a resist matrix is a serious concern. The incorporation of acid generators into polymers via covalent bonds has attracted much attention in overcoming the compatibility problem of acid generators with polymers and reducing the diffusion lengths of acids, which leads to a high resolution and a low line edge roughness (LER). Therefore, the resist performance characteristics of a polymer-bound photo-acid generator (PAG) and a polymer-blended PAG were investigated and compared. The numbers of acid molecules generated in the polymer-bound and polymer-blended PAGs upon exposure to extreme ultraviolet (EUV) were almost the same at both 5 and 10 mol % acid generator contents. However, the sensitivity of the polymer-blended PAG was higher than that of the polymer-bound PAG. Although the etching durabilities of the developed polymer-blended and polymer-bound PAGs were lower than that of conventional resist materials, the surface roughness of the polymer-bound PAG was lower than that of the polymer-blended PAG. The developed polymer-bound PAG resist showed an excellent performance (30 nm line and 80 nm pitch). Thus, it was proved that polymer-bound PAG resists are promising candidates for the resist materials of nanolithography, such as electron beam and EUV lithography.
Supernova Neutrino Detection
Authors: Scholberg Kate
Published: July 2012

A core-collapse supernova will produce an enormous burst of neutrinos of all flavors in the few-tens-of-MeV range. Measurement of the flavor, time, and energy structure of a nearby core-collapse neutrino burst will yield answers to many physics and astrophysics questions. The neutrinos left over from past cosmic supernovae are also observable, and their detection will improve knowledge of core-collapse rates and average neutrino emission. This review describes experimental techniques for detection of core-collapse neutrinos, as well as the sensitivities of current and future detectors.
Functional roles of the A335 and G338 residues of the proton-coupled folate transporter (PCFT-SLC46A1) mutated in hereditary folate malabsorption
Authors: Shin Daniel Sanghoon , Zhao Rongbao , Fiser Andras , Goldman David I.
Published: July 2012

The proton-coupled folate transporter (PCFT-SLC46A1) mediates intestinal folate absorption and folate transport across the choroid plexus, processes defective in hereditary folate malabsorption (HFM). This paper characterizes the functional defect, and the roles of two mutated PCFT residues, associated with HFM (G338R and A335D). The A335D-PCFT and other mutations at this residue result in an unstable protein; when expression of a mutant protein was preserved, function was always retained. The G338R and other charged mutants resulted in an unstable protein; substitutions with small neutral and polar amino acids preserved protein but with impaired function. Pemetrexed and methotrexate (MTX) influx kinetics mediated by the G338C mutant PCFT revealed marked (15- to 20-fold) decreases in Kt and Vmax compared with wild-type PCFT. In contrast, there was only a small (∼2-fold) decrease in the MTX influx Ki and an increase (∼3-fold) in the pemetrexed influx Ki for the G338C-PCFT mutant. Neither a decrease in pH to 4.5, nor an increase to 7.4, restored function of the G338C mutant relative to wild-type PCFT excluding a role for this residue in proton binding or proton coupling. Homology modeling localized the A335 and G338 residues embedded in the 9th transmembrane, consistent with the inaccessibility of the A335C and G338C proteins to MTS reagents. Hence, the loss of intrinsic G338C-PCFT function was due solely to impaired oscillation of the carrier between its conformational states. The data illustrate how alterations in carrier cycling can impact influx Kt without comparable alterations in substrate binding to the carrier.
A network-oriented perspective on cardiac calcium signaling
Authors: George Christopher H. , Parthimos Dimitris , Silvester Nicole C.
Published: July 2012

The normal contractile, electrical, and energetic function of the heart depends on the synchronization of biological oscillators and signal integrators that make up cellular signaling networks. In this review we interpret experimental data from molecular, cellular, and transgenic models of cardiac signaling behavior in the context of established concepts in cell network architecture and organization. Focusing on the cellular Ca2+ handling machinery, we describe how the plasticity and adaptability of normal Ca2+ signaling is dependent on dynamic network configurations that operate across a wide range of functional states. We consider how (mal)adaptive changes in signaling pathways restrict the dynamic range of the network such that it cannot respond appropriately to physiologic stimuli or perturbation. Based on these concepts, a model is proposed in which pathologic abnormalities in cardiac rhythm and contractility (e.g., arrhythmias and heart failure) arise as a consequence of progressive desynchronization and reduction in the dynamic range of the Ca2+ signaling network. We discuss how a systems-level understanding of the network organization, cellular noise, and chaotic behavior may inform the design of new therapeutic modalities that prevent or reverse the disease-linked unraveling of the Ca2+ signaling network.
Effect of aging on norepinephrine-related proliferative response in primary cultured periportal and perivenous hepatocytes
Authors: Kobayashi Tomonori , Saito Yohei , Ohtake Yosuke , Maruko Akiko , Yamamoto Yumi , Yamamoto Fumihiko , Kuwahara Yoshikazu , Fukumoto Motoi , Fukumoto Manabu , Ohkubo Yasuhito
Published: July 2012

Norepinephrine (NE) amplifies the mitogenic effect of EGF in a rat liver through the adrenergic receptor coupled with G protein, Ghα. Ghα is also known as a transglutaminase 2 (TG2), whose cross-linking activity is implicated in hepatocyte growth. Recently, we found that NE-induced amplification of EGF-induced DNA synthesis in hepatocytes obtained from perivenous regions of liver is caused by inhibiting the downregulation of EGF receptor (EGFR) by TG2. In the present study, we investigated the effect of aging on NE-related proliferative response. Hepatocytes were obtained from the liver of 7- and 90-wk-old rats. To examine this in detail, periportal hepatocytes (PPH) and perivenous hepatocytes (PVH) were isolated using the digitonin/collagenase perfusion technique. EGF or NE receptor binding was analyzed by Scatchard analysis. Changes in NE-induced DNA synthesis, G protein activity, and TG2 activity were measured. NE slightly potentiated [125I]EGF binding to EGFR, and EGF-induced DNA synthesis in PVH but not in PPH. [3H]NE binding studies indicated that PVH have a greater number of receptors than PPH, and that the number of receptors in both subpopulations increased with aging. NE-induced changes in G protein activity and TG2 activity in 90-wk-old rats were slight compared with 7-wk-old rats. These results suggest that NE results in a slight recovery effect on the age-related decline in EGF-induced DNA synthesis because of incomplete switching of the function from TG2 to Ghα.
Enhancement of Photocatalytic Activity of ZnO/SiO2by Nanosized Pt for Photocatalytic Degradation of Phenol in Wastewater
Authors: Mohamed R. M. , Barakat M. A.
Published: July 2012

ZnO- nanoparticles were synthesized by a sol-gel technique from and tetraethyl orthosilicate (TEOS). The synthesized samples were further modified by nanosized Pt from H2PtCl6solution through photoassisted deposition (PAD) and impregnation (Img) routes. The obtained samples were characterized by a series of techniques including X-ray diffraction (XRD), UV-Vis diffuse reflectance spectroscopy, N2adsorption, extended X-ray absorption fine structure (EXAFS), and transmission electron microscopy (TEM). The photocatalytic activity of the Pt-ZnO/ was evaluated by photocatalytic degradation of phenol in synthetic wastewater under UV-irradiation. Results obtained revealed that the surface area and the photocatalytic activity of the prepared samples were increased in the order ZnO/ < PAD: Pt-ZnO/ < img: Pt-ZnO/. The surface area decreased from 480 to 460 and 450 m2/g, while the efficiency of the phenol degradation increased from 80 to 85 and 100%, with the ZnO/, Img: Pt-ZnO-, and PAD: Pt-ZnO- samples, respectively.
Product Summability Transform of Conjugate Series of Fourier Series
Authors: Mishra Vishnu Narayan , Khatri Kejal , Mishra Lakshmi Narayan
Published: July 2012

A known theorem, Nigam (2010) dealing with the degree of approximation of conjugate of a signal belonging toLipξ(t)-class by(E,1)(C,1)product summability means of conjugate series of Fourier series has been generalized for the weightedW(Lr,ξ(t)),(r≥1),(t>0)-class, whereξ(t)is nonnegative and increasing function oft, byEn1Cn1~which is in more general form of Theorem 2 of Nigam and Sharma (2011).
Analysis and Design of Transformer-Based mm-Wave Transmit/Receive Switches
Authors: Adabi Ehsan , Niknejad Ali M.
Published: July 2012

Transformer-based shunt single pole, double-throw (SPDT) switches are analyzed, and design equations are provided. A mm-wave transformer-based SPDT shunt switch prototype was designed and fabricated in 90 nm digital CMOS process. It has a minimum insertion loss of 3.4 dB at 50 GHz from the single pole to the ON-thru port and a leakage of 19 dB from the single pole to the OFF-thru port. The isolation is 13.7 dB between the two thru ports. Large signal measurements verify that the switch is capable of handling +14 dBm of input power at its 1 dB compression point. The fabricated SPDT switch has a minute active area size of 60 μm×60 μm.
Refinement Method for Weighting Scheme of Fully Spatial Beamformer
Authors: Bunsanit Chayanit , Uthansakul Peerapong , Uthansakul Monthippa
Published: July 2012

So far, a wideband spatial beamformer has been proposed. This kind of beamformer has a major contribution as its weighting coefficients are real valued in which they can be simply realized by attenuators or amplifiers. However, so far, the range of attenuation or amplification is relatively large which is not practical for hardware realization. Therefore, this paper proposes a concept to reduce the range of weighting coefficients hence, the hardware realization becomes practical. In this paper, a full prototype of wideband spatial beamformer is constructed to reflect the true beamforming performance of the proposed refinement method. Its radiation patterns obtained from simulation and measurement are compared. As a result, we can reduce the attenuation or amplification range while some radiation characteristic is remained.
Adequacy of Semitendinosus Tendon Alone for Anterior Cruciate Ligament Reconstruction Graft and Prediction of Hamstring Graft Size by Evaluating Simple Anthropometric Parameters
Authors: Stergios Papastergiou G. , Georgios Konstantinidis A. , Konstantinos Natsis , Efthymia Papathanasiou , Nikolaos Koukoulias , Alexandros Papadopoulos G.
Published: July 2012

Introduction. Preoperative identification of patients with inadequate hamstring grafts for anterior cruciate ligament reconstruction is still a subject of interest.
Purpose. The purpose of this study was to determine whether the semitendinosus tendon length is adequate for four-strand graft harvested by common technique (without bone plug) and whether there is correlation of gracilis and semitendinosus tendon grafts length and diameter of quadrupled graft with anthropometric parameters.
Materials and Methods. In this retrospective study, 61 patients (45 males, 16 females) undergoing ACL reconstruction using four-strand hamstring autograft tendons were included.
Results. The length of semitendinosus tendon, harvested by the common technique, was in 21% of our cases inadequate in order to be used alone as a four-strand graft especially in females (43%). There was moderate correlation between semitendinosus and gracilis graft diameter and patient’s height and weight and fair correlation to BMI. We found no statistically important predictor for graft diameter in female patients.
Conclusions. The length of semitendinosus tendon, harvested by common technique, is usually inadequate to be used alone as a four-strand graft especially in females. The most reliable predictor seems to be patient’s height in males. In female patients, there is no statistically important predictor.
An Uncommon Case of Pediatric Neurobrucellosis Associated with Intracranial Hypertension
Authors: Sinopidis Xenophon , Kaleyias Joseph , Mitropoulou Konstantina , Triga Maria , Kothare Sanjeev V. , Mantagos Stefanos
Published: July 2012

We present the case of a 4-year-old boy who was admitted to hospital with intracranial hypertension, headache, diplopia, papilledema, and a normal brain MRI.Brucella melitensisin the cerebrospinal fluid was confirmed with PCR assay. We believe that neurobrucellosis should be included in the differential diagnosis when headaches persist following brucellosis. In addition, we suggest that when cerebrospinal fluid culture is negative, PCR may prove to be an optimal alternative tool for an immediate and accurate diagnosis.
Kikuchi-Fujimoto Disease: A Case Report and Literature Review
Authors: Veer Vikrant , Lim Albert , Issing Wolfgang
Published: July 2012

Case. 38-year-old lady was referred to the ENT clinic with history of right-sided facial pain, otalgia, and odynophagia. Clinical examination revealed enlarged right-sided lymph nodes in the neck. Further radiological scans showed a mass near the carotid and enlarged level V lymph nodes. Lymphoma was initially suspected. Fine-needle aspiration and excision biopsy were undertaken. Histological analysis later suggested Kikuchi-Fujimoto disease, also known as histiocytic necrotising lymphadenitis.Literature Review. Kikuchi-Fujimoto disease (KFD) was described in 1972 as lymphadenitis with focal proliferation of reticular cells accompanied by numerous histiocytes and extensive nuclear debris. KFD, frequently found in East Asian countries, is rare in the UK. No definite aetiology of KFD is known despite autoimmune and infection factors being suggested. The diagnostic hallmark is histological findings from lymph nodes. Malignancy should be excluded. This condition is mainly self-limiting; hence, management is limited to supportive care. Steroid therapy could be used in severe cases. KFD is relatively unknown in the UK and this case report aims to highlight its occurrence in our population.
Experimental Validation of the Electrokinetic Theory and Development of Seismoelectric Interferometry by Cross-Correlation
Authors: Schoemaker F. C. , Grobbe N. , Schakel M. D. , de Ridder S. A. L. , Slob E. C. , Smeulders D. M. J.
Published: July 2012

We experimentally validate a relatively recent electrokinetic formulation of the streaming potential (SP) coefficient as developed by Pride (1994). The start of our investigation focuses on the streaming potential coefficient, which gives rise to the coupling of mechanical and electromagnetic fields. It is found that the theoretical amplitude values of this dynamic SP coefficient are in good agreement with the normalized experimental results over a wide frequency range, assuming no frequency dependence of the bulk conductivity. By adopting the full set of electrokinetic equations, a full-waveform wave propagation model is formulated. We compare the model predictions, neglecting the interface response and modeling only the coseismic fields, with laboratory measurements of a seismic wave of frequency 500 kHz that generates electromagnetic signals. Agreement is observed between measurement and electrokinetic theory regarding the coseismic electric field. The governing equations are subsequently adopted to study the applicability of seismoelectric interferometry. It is shown that seismic sources at a single boundary location are sufficient to retrieve the 1D seismoelectric responses, both for the coseismic and interface components, in a layered model.
Fatty Acid Composition of Phospholipids and in the Central and External Positions of Triacylglycerol in Muscle and Subcutaneous Fat of Beef Steers Fed Diets Supplemented with Oil Containing n6 and n3 Fatty Acids While Undergoing One of Three 48 h Feed Withdrawal Treatments
Authors: Margetak C. , Travis G. , Entz T. , Mir P. S. , Wei S. , Dodson M. V.
Published: July 2012

This study was designed to determine the effects of dietary oil and feed withdrawal treatments on fatty acid composition of phospholipids of triacylglycerol in pars costalis diaphragmatis muscle and subcutaneous fat from the brisket. A 2 × 3 factorial experiment was conducted with crossbred steers with an initial body weight of 280.5 ± 5.8 kg. Steers were fed either a control or an oil containing diet where 5% of the control diet was replaced with an equal mixture sunflower and flax oil while undergoing one of three feed withdrawal treatments: no withdrawal, a single 48 h withdrawal before initiation of fattening at one year of age, or 48 h withdrawal at 8 wk intervals from weaning to initiation of fattening. At time of processing samples of muscle and fat were obtained and analyzed to determine fatty acid composition. Disproportionate distribution of the fatty acids was observed by diet, feed withdrawal regimen and whether the sample was from muscle or fat. Differences are discussed in detail, and our data suggests a special function for the fatty acids that accumulate in specific positions of the triacylglycerol due to treatment.
Single‐Stage Coupled‐Inductor Sepic‐Type HB‐LED Driver with Soft Switching for Universal Line Input
Authors: Shen Chih-Lung , Chen Kuo-Kuang
Published: July 2012

This paper proposes a single‐stage Sepic‐type high brightness LED driver for universal line input to perform power factor correcting and LED dimming. In the driver, a coupled inductor is introduced to replace with two separate inductors to lower volume and cost. A soft‐switching cell is embedded into the driver to obtain zero‐voltage switching (ZVS) feature so as to furthermore improve driver efficiency. Mathematical derivation and detailed discussion is presented. A prototype is designed, analyzed and implemented, which demonstrates the feasibility of the driver and verifies the theoretical analysis.
Liver Transplantation and Hepatitis C
Authors: Akamatsu Nobuhisa , Sugawara Yasuhiko
Published: July 2012

Hepatitis-C-virus- (HCV-) related end-stage cirrhosis is the primary indication for liver transplantation in many countries. Unfortunately, however, HCV is not eliminated by transplantation and graft reinfection is universal, resulting in fibrosis, cirrhosis, and finally graft decompensation. The use of poor quality organs, particularly from older donors, has a highly negative impact on the severity of recurrence and patient/graft survival. Although immunosuppressive regimens have a considerable impact on the outcome, the optimal regimen after liver transplantation for HCV-infected patients remains unclear. Disease progression monitoring with protocol biopsy and new noninvasive methods is essential for predicting patient/graft outcome and starting antiviral treatment with the appropriate timing. Antiviral treatment with pegylated interferon and ribavirin is currently considered the most promising regimen with a sustained viral response rate of around 30% to 35%, although the survival benefit of this regimen remains to be investigated. Living-donor liver transplantation is now widely accepted as an established treatment for HCV cirrhosis and the results are equivalent to those of deceased donor liver transplantation.