bluuebunny/crossref_metadata_2025 huggingface dataset:
Random mutagenesis and topology analysis of the autoinducing peptide biosynthesis proteins in Staphylococcus aureus
Authors: Thoendel Matthew , Horswill Alexander R.
Published: December 2012

The Staphylococcus aureus accessory gene regulator (agr) is a peptide signalling system that regulates the production of secreted virulence factors required to cause infections. The signal controlling agr function is a 7‐9 residue thiolactone‐containing peptide called an autoinducing peptide (AIP) that is biosynthesized from the AgrD precursor by the membrane peptidase AgrB. To gain insight into AgrB and AgrD function, the agrBD genes were mutagenized and screened for deficiencies in AIP production. In total, single‐site mutations at 14 different residues in AgrD were identified and another 20 within AgrB. In AgrD, novel mutations were characterized in the N‐terminal leader and throughout the central region encoding the AIP signal. In AgrB, most mutations blocked peptidase activity, but mutations in the K129–K131 residues were defective in a later step in AIP biosynthesis, separating the peptidase function from thiolactone ring formation and AIP transport. With the identification of residues in AgrB essential for AgrD processing, we reevaluated the membrane topology and the new model predicts four transmembrane helices and a potential re‐entrant loop on the cytoplasmic face. Finally, co‐immunoprecipitation studies indicate that AgrB forms oligomeric structures within the membrane. These studies provide further insight into the unique structural and functional properties of AgrB.
Development of autoantibodies after pediatric liver transplantation
Authors: Chen Ching‐Yi , Ho Ming‐Chih , Wu Jia‐Feng , Jeng Yung‐Ming , Chen Huey‐Ling , Chang Mei‐Hwei , Lee Po‐Huang , Hu Rey‐Heng , Ni Yen‐Hsuan
Published: December 2012

Dn‐AIH is a long‐term complication after LT. The aim of this study was to analyze the occurrence of autoantibodies in pediatric recipients and the clinical significance. From 1992 to 2008, 96 pediatric LT for non‐autoimmune liver diseases were performed in 94 children in our institution. Serum autoantibodies were checked in 68 subjects (73.9%). A positive autoantibody was defined as titers ≥1:40 for ANA, or ≥1:20 for ASMA, anti‐LKM, and AMA. Autoantibodies were detectable in 51 of 68 patients (75.0%). There was positivity for ANA in 30 patients, ASMA in 32, and AMA in three, while anti‐LKM was all negative. Immunosuppressive treatment with CsA, more than one episode of rejection, and abnormal ALT were risk factors for the development of autoantibodies. The incidence of the development of autoantibodies was 75.0% in pediatric LT cases in this study. ASMA was the most commonly found autoantibody. Autoantibodies may not play a sentinel role for dn‐AIH after LT.
Growth and temperature‐related phenotypic plasticity in the cyanobacterium Cylindrospermopsis raciborskii
Authors: Soares Maria Carolina S. , Lürling Miquel , Huszar Vera L. M.
Published: December 2012

Cylindrospermopsis raciborskii is an invasive and potentially toxic cyanobacterium, which has recently spread worldwide, mainly because of its tolerance to a wide range of climatic conditions. C. raciborskii is able to change several traits in response to environmental changes and its morphology is also affected by these changes (especially in nutrients). We also expected temperature to affect the morphology of this cyanobacterium. We examined the growth and morphology of C. raciborskii at different temperatures and compared laboratory results to the morphology of this cyanobacterium in situ. As expected, growth rates increased with temperature. In addition, a high carrying capacity at 32°C suggests that this cyanobacterium is able to form more dense blooms at high temperatures. Fragile trichomes and low growth rates were observed at 12°C. An increase in the growth rate related to temperature resulted in a decrease in trichome length, with shorter trichomes at 32°C. The same pattern was observed in wild populations of C. raciborskii in a tropical reservoir, where shorter trichomes were observed in warmer months, when biomass was highest. This species' high ability to adapt to different environmental conditions throughout the year (i.e., nutrients, temperature) may have provided it with an additional advantage to increase its perennial blooms, mainly in tropical regions.
Broke, Ill, and Obese: Is There an Effect of Household Debt on Health?
Authors: Keese Matthias , Schmitz Hendrik
Published: December 2012

We analyze the association between household indebtedness and different health outcomes using data from theGermanSocio‐EconomicPanel from 1999 to 2009. We control for unobserved heterogeneity by applying fixed‐effects methods and furthermore use a subsample of constantly employed individuals plus lagged debt variables to reduce problems of reverse causality. We apply different measures of household indebtedness, such as the percentage shares of household income spent on consumer credit and home loan repayments (which indicate the severity of household indebtedness) and a binary variable of relative overindebtedness (which indicates a precarious debt situation). We find all debt measures to be strongly correlated with health satisfaction, mental health, and obesity. This relationship vanishes for obesity after controlling for unobserved heterogeneity while it stays significant with respect to worse physical and mental health.
Modelling and simulation of blood collection systems: improvement of human resources allocation for better cost‐effectiveness and reduction of candidate donor abandonment
Authors: Alfonso E. , Xie X. , Augusto V. , Garraud O.
Published: December 2012

Background  This study addresses the modelling and simulation of blood collection for fixed blood collection sites in a medium‐sized large French city, as well as mobile blood collection in urban and rural environments.

Study Design and Methods  Formal Petri net models were used to describe all relevant donor flows of the various blood collection systems; the Petri net models were converted onto discrete‐event simulation models, allowing the evaluation of a large number of scenarios and configurations of blood collection systems. Quantitative models were proposed that encompassed all components of the blood collection systems, such as the donor arrival process, resource capacities and performance indicators. Appropriate experimental designs and cost‐effectiveness analyses were used to determine the best configurations of human resources and donor appointment strategies.

Results  The donor service level depended on both adequate human resources capacity and appropriate appointment strategies. These decisions depend on the distribution during the day of walk‐in donors.

Conclusion  Models permit to improve management of blood collection; they have now partially entered the real situation, awaiting further implementation.
Incomplete Restoration of Homeostatic Shear Stress Within Arteriovenous Fistulae
Authors: McGah Patrick M. , Leotta Daniel F. , Beach Kirk W. , Eugene Zierler R. , Aliseda Alberto
Published: December 2012

Arteriovenous fistulae are surgically created to provide adequate access for dialysis patients suffering from end-stage renal disease. It has long been hypothesized that the rapid blood vessel remodeling occurring after fistula creation is, in part, a process to restore the mechanical stresses to some preferred level, i.e., mechanical homeostasis. We present computational hemodynamic simulations in four patient-specific models of mature arteriovenous fistulae reconstructed from 3D ultrasound scans. Our results suggest that these mature fistulae have remodeled to return to ‘‘normal’’ shear stresses away from the anastomoses: about 1.0 Pa in the outflow veins and about 2.5 Pa in the inflow arteries. Large parts of the anastomoses were found to be under very high shear stresses >15 Pa, over most of the cardiac cycle. These results suggest that the remodeling process works toward restoring mechanical homeostasis in the fistulae, but that the process is limited or incomplete, even in mature fistulae, as evidenced by the elevated shear at or near the anastomoses. Based on the long term clinical viability of these dialysis accesses, we hypothesize that the elevated nonhomeostatic shear stresses in some portions of the vessels were not detrimental to fistula patency.
A deterministic compressive sensing model for bat biosonar
Authors: Hague David A. , Buck John R. , Bilik Igal
Published: December 2012

The big brown bat (Eptesicus fuscus) uses frequency modulated (FM) echolocation calls to accurately estimate range and resolve closely spaced objects in clutter and noise. They resolve glints spaced down to 2 μs in time delay which surpasses what traditional signal processing techniques can achieve using the same echolocation call. The Matched Filter (MF) attains 10–12 μs resolution while the Inverse Filter (IF) achieves higher resolution at the cost of significantly degraded detection performance. Recent work by Fontaine and Peremans [J. Acoustic. Soc. Am. 125, 3052–3059 (2009)] demonstrated that a sparse representation of bat echolocation calls coupled with a decimating sensing method facilitates distinguishing closely spaced objects over realistic SNRs. Their work raises the intriguing question of whether sensing approaches structured more like a mammalian auditory system contains the necessary information for the hyper-resolution observed in behavioral tests. This research estimates sparse echo signatures using a gammatone filterbank decimation sensing method which loosely models the processing of the bat's auditory system. The decimated filterbank outputs are processed with ℓ1 minimization. Simulations demonstrate that this model maintains higher resolution than the MF and significantly better detection performance than the IF for SNRs of 5–45 dB while undersampling the return signal by a factor of six.
A vessel noise budget for Admiralty Inlet, Puget Sound, Washington (USA)
Authors: Bassett Christopher , Polagye Brian , Holt Marla , Thomson Jim
Published: December 2012

One calendar year of Automatic Identification System (AIS) ship-traffic data was paired with hydrophone recordings to assess ambient noise in northern Admiralty Inlet, Puget Sound, WA (USA) and to quantify the contribution of vessel traffic. The study region included inland waters of the Salish Sea within a 20 km radius of the hydrophone deployment site. Spectra and hourly, daily, and monthly ambient noise statistics for unweighted broadband (0.02–30 kHz) and marine mammal, or M-weighted, sound pressure levels showed variability driven largely by vessel traffic. Over the calendar year, 1363 unique AIS transmitting vessels were recorded, with at least one AIS transmitting vessel present in the study area 90% of the time. A vessel noise budget was calculated for all vessels equipped with AIS transponders. Cargo ships were the largest contributor to the vessel noise budget, followed by tugs and passenger vessels. A simple model to predict received levels at the site based on an incoherent summation of noise from different vessels resulted in a cumulative probability density function of broadband sound pressure levels that shows good agreement with 85% of the temporal data.
Numerical instabilities and three-dimensional electromagnetic articulography
Authors: Stella Massimo , Bernardini Paolo , Sigona Francesco , Stella Antonio , Grimaldi Mirko , Gili Fivela Barbara
Published: December 2012

The AG500 electromagnetic articulograph is widely used to reconstruct the movements of the articulatory organs. Nevertheless, some anomalies in its performance have been observed. It is well known that accuracy of the device is affected by electromagnetic interference and possible hardware failures or damage to the sensors. In this study, after eliminating any hardware or electromagnetic source of disturbance, a set of trials was carried out. The tests prove that anomalies in sensor position tracking are systematic in certain regions within the recording volume and, more importantly, show a specific pattern that can be clearly attributed to a wrong convergence of the calculation method.
A tone analyzer based on a piezoelectric polymer and organic thin film transistors
Authors: Hsu Yu-Jen , Kymissis Ioannis
Published: December 2012

A tone analyzer is demonstrated using a distributed resonator architecture on a tensioned piezoelectric polyvinyledene diuoride (PVDF) sheet. This sheet is used as both the resonator and detection element. Two architectures are demonstrated; one uses distributed, directly addressed elements as a proof of concept, and the other integrates organic thin film transistor-based transimpedance amplifiers directly with the PVDF to convert the piezoelectric charge signal into a current signal. The PVDF sheet material is instrumented along its length, and the amplitude response at 15 sites is recorded and analyzed as a function of the frequency of excitation. The determination of the dominant component of an incoming tone is demonstrated using linear system decomposition of the time-averaged response of the sheet and is performed without any time domain analysis. This design allows for the determination of the spectral composition of a sound using the mechanical signal processing provided by the amplitude response and eliminates the need for time-domain downstream signal processing of the incoming signal.
Sound field separation with sound pressure and particle velocity measurements
Authors: Fernandez-Grande Efren , Jacobsen Finn , Leclère Quentin
Published: December 2012

In conventional near-field acoustic holography (NAH) it is not possible to distinguish between sound from the two sides of the array, thus, it is a requirement that all the sources are confined to only one side and radiate into a free field. When this requirement cannot be fulfilled, sound field separation techniques make it possible to distinguish between outgoing and incoming waves from the two sides, and thus NAH can be applied. In this paper, a separation method based on the measurement of the particle velocity in two layers and another method based on the measurement of the pressure and the velocity in a single layer are proposed. The two methods use an equivalent source formulation with separate transfer matrices for the outgoing and incoming waves, so that the sound from the two sides of the array can be modeled independently. A weighting scheme is proposed to account for the distance between the equivalent sources and measurement surfaces and for the difference in magnitude between pressure and velocity. Experimental and numerical studies have been conducted to examine the methods. The double layer velocity method seems to be more robust to noise and flanking sound than the combined pressure-velocity method, although it requires an additional measurement surface. On the whole, the separation methods can be useful when the disturbance of the incoming field is significant. Otherwise the direct reconstruction is more accurate and straightforward.
Whistle vocalizations of Indo-Pacific bottlenose dolphins (Tursiops aduncus) inhabiting the south-west Indian Ocean
Authors: Gridley Tess , Berggren Per , Cockcroft Victor G. , Janik Vincent M.
Published: December 2012

Populations of Indo-Pacific bottlenose dolphin (Tursiops aduncus) are distributed along coastal regions of the south-west Indian Ocean (SWIO), from South Africa to Kenya. An account of whistles from wild T. aduncus inhabiting the SWIO is provided here. Recordings were made at Plettenberg Bay (South Africa) and Zanzibar Island (Tanzania) and the frequency trace of whistle contours (n = 1677) was extracted. Multiple parameters were measured from each whistle and compared between regions and encounters. Regional variation was significant in all parameters assessed except for start and middle frequency (frequency at half the duration). Whistles from Zanzibar Island ended on average 4 kHz higher than those from Plettenberg Bay, and had a steeper frequency gradient. However, mean frequencies differed by <1 kHz and population averages for the adopted frequency distribution showed similar patterns, with a peak between 5 and 7 kHz. Whistle parameters were strongly influenced by recording encounter, likely reflecting the presence of different individuals, group compositions and behavioral contexts during recording occasions. Comparisons within the genus showed that T. aduncus from the SWIO have amongst the lowest start and minimum frequency of whistles within Tursiops.
Deterministic forward scatter from surface gravity waves
Authors: Deane Grant B. , Preisig James C. , Tindle Chris T. , Lavery Andone , Dale Stokes M.
Published: December 2012

Deterministic structures in sound reflected by gravity waves, such as focused arrivals and Doppler shifts, have implications for underwater acoustics and sonar, and the performance of underwater acoustic communications systems. A stationary phase analysis of the Helmholtz–Kirchhoff scattering integral yields the trajectory of focused arrivals and their relationship to the curvature of the surface wave field. Deterministic effects along paths up to 70 water depths long are observed in shallow water measurements of surface-scattered sound at the Martha's Vineyard Coastal Observatory. The arrival time and amplitude of surface-scattered pulses are reconciled with model calculations using measurements of surface waves made with an upward-looking sonar mounted mid-way along the propagation path. The root mean square difference between the modeled and observed pulse arrival amplitude and delay, respectively, normalized by the maximum range of amplitudes and delays, is found to be 0.2 or less for the observation periods analyzed. Cross-correlation coefficients for modeled and observed pulse arrival delays varied from 0.83 to 0.16 depending on surface conditions. Cross-correlation coefficients for normalized pulse energy for the same conditions were small and varied from 0.16 to 0.06. In contrast, the modeled and observed pulse arrival delay and amplitude statistics were in good agreement.
Stream segregation on a single electrode as a function of pulse rate in cochlear implant listeners
Authors: Duran Sara I. , Collins Leslie M. , Throckmorton Chandra S.
Published: December 2012

While cochlear implants (CIs) usually provide high levels of speech recognition in quiet, speech recognition in noise remains challenging. To overcome these difficulties, it is important to understand how implanted listeners separate a target signal from interferers. Stream segregation has been studied extensively in both normal and electric hearing, as a function of place of stimulation. However, the effects of pulse rate, independent of place, on the perceptual grouping of sequential sounds in electric hearing have not yet been investigated. A rhythm detection task was used to measure stream segregation. The results of this study suggest that while CI listeners can segregate streams based on differences in pulse rate alone, the amount of stream segregation observed decreases as the base pulse rate increases. Further investigation of the perceptual dimensions encoded by the pulse rate and the effect of sequential presentation of different stimulation rates on perception could be beneficial for the future development of speech processing strategies for CIs.
The contributions of onset and offset echo delays to auditory spatial perception in human listeners
Authors: Donovan Jeff M. , Nelson Brian S. , Takahashi Terry T.
Published: December 2012

In echoic environments, direct sounds dominate perception even when followed by their reflections. As the delay between the direct (lead) source and the reflection (lag) increases, the reflection starts to become localizable. Although this phenomenon, which is part of the precedence effect, is typically studied with brief transients, leading and lagging sounds often overlap in time and are thus composed of three distinct segments: the “superposed” segment, when both sounds are present together, and the “lead-alone” and “lag-alone” segments, when leading and lagging sounds are present alone, respectively. Recently, it was shown that the barn owl (Tyto alba) localizes the lagging sound when the lag-alone segment, not the lead-alone segment, is lengthened. This was unexpected given the prevailing hypothesis that a leading sound may briefly desensitize the auditory system to sounds arriving later. The present study confirms this finding in humans under conditions that minimized the role of the superposed segment in the localization of either source. Just as lengthening the lag-alone segment caused the lagging sound to become more salient, lengthening the lead-alone segment caused the leading sound to become more salient. These results suggest that the neural representations of the lead and lag are independent of one another.
Stream segregation with high spatial acuity
Authors: Middlebrooks John C. , Onsan Zekiye A.
Published: December 2012

Spatial hearing is widely regarded as helpful in recognizing a sound amid other competing sounds. It is a matter of debate, however, whether spatial cues contribute to “stream segregation,” which refers to the specific task of assigning multiple interleaved sequences of sounds to their respective sources. The present study employed “rhythmic masking release” as a measure of the spatial acuity of stream segregation. Listeners discriminated between rhythms of noise-burst sequences presented from free-field targets in the presence of interleaved maskers that varied in location. For broadband sounds in the horizontal plane, target-masker separations of ≥8° permitted rhythm discrimination with d′ ≥ 1; in some cases, such thresholds approached listeners’ minimum audible angles. Thresholds were the same for low-frequency sounds but were substantially wider for high-frequency sounds, suggesting that interaural delays provided higher spatial acuity in this task than did interaural level differences. In the vertical midline, performance varied dramatically as a function of noise-burst duration with median thresholds ranging from >30° for 10-ms bursts to 7.1° for 40-ms bursts. A marked dissociation between minimum audible angles and masking release thresholds across the various pass-band and burst-duration conditions suggests that location discrimination and spatial stream segregation are mediated by distinct auditory mechanisms.
Experimental assessment of four ultrasound scattering models for characterizing concentrated tissue-mimicking phantoms
Authors: Franceschini Emilie , Guillermin Régine
Published: December 2012

Tissue-mimicking phantoms with high scatterer concentrations were examined using quantitative ultrasound techniques based on four scattering models: The Gaussian model (GM), the Faran model (FM), the structure factor model (SFM), and the particle model (PM). Experiments were conducted using 10- and 17.5-MHz focused transducers on tissue-mimicking phantoms with scatterer concentrations ranging from 1% to 25%. Theoretical backscatter coefficients (BSCs) were first compared with the experimentally measured BSCs in the forward problem framework. The measured BSC versus scatterer concentration relationship was predicted satisfactorily by the SFM and the PM. The FM and the PM overestimated the BSC magnitude at actual concentrations greater than 2.5% and 10%, respectively. The SFM was the model that better matched the BSC magnitude at all the scatterer concentrations tested. Second, the four scattering models were compared in the inverse problem framework to estimate the scatterer size and concentration from the experimentally measured BSCs. The FM did not predict the concentration accurately at actual concentrations greater than 12.5%. The SFM and PM need to be associated with another quantitative parameter to differentiate between low and high concentrations. In that case, the SFM predicted the concentration satisfactorily with relative errors below 38% at actual concentrations ranging from 10% to 25%.
Perceptual evaluation of violins: A quantitative analysis of preference judgments by experienced players
Authors: Saitis Charalampos , Giordano Bruno L. , Fritz Claudia , Scavone Gary P.
Published: December 2012

The overall goal of the research presented here is to better understand how players evaluate violins within the wider context of finding relationships between measurable vibrational properties of instruments and their perceived qualities. In this study, the reliability of skilled musicians to evaluate the qualities of a violin was examined. In a first experiment, violinists were allowed to freely play a set of different violins and were then asked to rank the instruments by preference. Results showed that players were self-consistent, but a large amount of inter-individual variability was present. A second experiment was then conducted to investigate the origin of inter-individual differences in the preference for violins and to measure the extent to which different attributes of the instrument influence preference. Again, results showed large inter-individual variations in the preference for violins, as well as in assessing various characteristics of the instruments. Despite the significant lack of agreement in preference and the variability in how different criteria are evaluated between individuals, violin players tend to agree on the relevance of sound “richness” and, to a lesser extent, “dynamic range” for determining preference.
Suppression of Oxidative Stress by β-Hydroxybutyrate, an Endogenous Histone Deacetylase Inhibitor
Authors: Shimazu Tadahiro , Hirschey Matthew D. , Newman John , He Wenjuan , Shirakawa Kotaro , Le Moan Natacha , Grueter Carrie A. , Lim Hyungwook , Saunders Laura R. , Stevens Robert D. , Newgard Christopher B. , Farese Robert V. , de Cabo Rafael , Ulrich Scott , Akassoglou Katerina , Verdin Eric
Published: December 2012

Stress Protector

During prolonged fasting, the oxidation of fatty acids leads to increased accumulation of
d
-β-hydroxybutyrate (βOHB) in the bloodstream. Such increased concentrations of βOHB inhibit class I histone deacetylases. Histone acetylation in turn influences transcriptional activity at various genes.

Shimazu
et al.

(p.
211
, published online 6 December; see the Perspective by

Sassone-Corsi

) found that among the genes showing increased transcription in animals treated with high concentrations of βOHB were two genes implicated in cellular responses to oxidative stress. When treated ahead of time with βOHB, mice were protected from the toxic effects of the oxidative stress causing poison paraquat.
Genomic Plasticity Enables a Secondary Electron Transport Pathway in Shewanella oneidensis
Authors: Schicklberger M. , Sturm G. , Gescher J.
Published: December 2012

Microbial dissimilatory iron reduction is an important biogeochemical process. It is physiologically challenging because iron occurs in soils and sediments in the form of insoluble minerals such as hematite or ferrihydrite.Shewanella oneidensisMR-1 evolved an extended respiratory chain to the cell surface to reduce iron minerals. Interestingly, the organism evolved a similar strategy for reduction of dimethyl sulfoxide (DMSO), which is reduced at the cell surface as well. It has already been established that electron transfer through the outer membrane is accomplished via a complex in which β-barrel proteins enable interprotein electron transfer between periplasmic oxidoreductases and cell surface-localized terminal reductases. MtrB is the β-barrel protein that is necessary for dissimilatory iron reduction. It forms a complex together with the periplasmic decahemec-type cytochrome MtrA and the outer membrane decahemec-type cytochrome MtrC. Consequently,mtrBdeletion mutants are unable to reduce ferric iron. The data presented here show that this inability can be overcome by a mobile genomic element with the ability to activate the expression of downstream genes and which is inserted within the SO4362 gene of the SO4362-to-SO4357 gene cluster. This cluster carries genes similar tomtrAandmtrBand encoding a putative cell surface DMSO reductase. Expression of SO4359 and SO4360 alone was sufficient to complement not only anmtrBmutant under ferric citrate-reducing conditions but also a mutant that furthermore lacks any outer membrane cytochromes. Hence, the putative complex formed by the SO4359 and SO4360 gene products is capable not only of membrane-spanning electron transfer but also of reducing extracellular electron acceptors.
Exact solutions of the Einstein–Maxwell equations with linear equation of state
Authors: Feroze Tooba
Published: December 2012

Two new classes of solutions of the Einstein–Maxwell field equations are obtained by substituting a general linear equation of state into the energy–momentum conservation equation. We have considered static, anisotropic, and spherically symmetric charged perfect fluid distribution of matter with a particular form of gravitational potential. Expressions for the mass–radius ratio, the surface, and the central red shift horizons are given for these solutions.
B0 → J/ψf2(1270) decay in QCD factorization
Authors: Sayahi Mahboobeh , Mahraban Hossein
Published: December 2012

In this paper, the hadronic decay B0 → J/ψf2(1270) has been analyzed using the “QCD factorization” method. The effective coefficients [Formula: see text] have been calculated for three helicity states (h = 0, +, –) which give three contributions of amplitude. We have assumed two scenarios for J/ψ. First, we have considered that J/ψ behaves as a light meson compared to the B meson and second, we have considered the mass of J/ψ in our calculations meaning that mJ/ψ/mb is held fixed. The branching ratios are calculated in these two scenarios and also in different energy scales (μ = mb, μ = mb/2, and μ = 2mb). The obtained results are in agreement with available experimental data for the second scenario and μ = 2mb.
A sine-Gordon soliton star model with a mix of dark energy and Fermi matter 1Project Supported by Natural Science Foundation of Sichuan Education Committee under Grant No.11ZA100.
Authors: Su Wen-Jie , Yan Jun
Published: December 2012

A sine-Gordon soliton star model with a mix of dark energy and Fermi matter is studied in the two-dimensional Brans–Dicke gravity model. The phase structure is analysed for a strong-coupling Thirring model. Subsequently, a soliton star model with cool Fermi matter coupling is constructed. We found that the soliton state and the mass of a star can change the density and pressure of matter at certain temperatures. Moreover, the stability of dark energy in the center of a star is proved when the coupling coefficient of the scalar field and Fermi matter satisfies some constraint conditions.
Quantum star-graph analogues of PT-symmetric square wells
Authors: Znojil Miloslav
Published: December 2012

We recall the solvable [Formula: see text]-symmetric quantum square well on an interval of x ∈ (–L, L) := [Formula: see text] (with an α-dependent non-Hermiticity given by Robin boundary conditions) and generalize it. In essence, we just replace the support interval [Formula: see text] (reinterpreted as an equilateral two-pointed star graph with Kirchhoff matching at the vertex x = 0) with a q-pointed equilateral star graph [Formula: see text] endowed with the simplest complex-rotation-symmetric external α-dependent Robin boundary conditions. The remarkably compact form of the secular determinant is then deduced. Its analysis reveals that (i) at any integer q = 2, 3, …, there exists the same q-independent and infinite subfamily of the real energies, and (ii) at any special q = 2, 6, 10, …, there exists another, additional, q-dependent infinite subfamily of the real energies. In the spirit of the recently proposed dynamical construction of the Hilbert space of a quantum system, the physical bound-state interpretation of these eigenvalues is finally proposed.
COMPLEX AND PARACOMPLEX STRUCTURES ON HOMOGENEOUS PSEUDO-RIEMANNIAN FOUR-MANIFOLDS
Authors: CALVARUSO GIOVANNI , FINO ANNA
Published: December 2012

We completely classify invariant Hermitian and Kähler structures, together with their paracomplex analogues, on four-dimensional homogeneous pseudo-Riemannian manifolds with nontrivial isotropy subalgebra.
MIGRATION OF CHARGED SPECIES IN LIPID BILAYER MEMBRANES UNDER AN ELECTRIC FIELD
Authors: WANG XUEJING , WANG LEI , HAN XIAOJUN , GUO CHANGJUN
Published: December 2012

This paper reviews recent progress in studies on the migration of charged species, including charged lipids, membrane-attached proteins and vesicles, and integrated membrane proteins, in lipid bilayer membranes under an external electric field. The migration of these charged substances is controlled by the interplay of electrophoresis and electroosmosis. This phenomenon can be employed to separate the charged lipids and membrane-attached proteins, and concentrate integrated membrane proteins.
DOUBLE SPIN ASYMMETRY ALT IN THE PRODUCTION OF PHOTONS, HADRONS, AND JETS
Authors: PITONYAK DANIEL
Published: December 2012

We calculate the double spin asymmetry (DSA) ALT in proton-proton (pp) collisions for the production of photons, hadrons, and jets in the collinear twist-3 framework. These processes allows us for the first time to access a complete set of collinear twist-3 functions. We also give numerical estimates for the asymmetries of which photon production shows the most promise of a measurable effect. Furthermore, we comment on how these asymmetries would allow us to probe the gluon helicity down to as of yet unexplored x values, remark on the importance of these effects in determining the evolution of the Efremov-Teryaev-Qiu-Sterman (ETQS) function TF(x, x), and discuss their usefulness in resolving the true mechanism behind the large transverse single spin asymmetries (SSAs) measured in pp collisions.
QCD EVOLUTION AND TMD/SPIN EXPERIMENTS
Authors: CHEN JIAN-PING
Published: December 2012

Transverse Spin and Transverse Momemtum Dependent (TMD) distribution study has been one of the main focuses of hadron physics in recent years. The initial exploratory Semi-Incluisve Deep-Inelastic-Scattering (SIDIS) experiments with transversely polarized proton and deuteron from HERMES and COMPASS attracted great attention and lead to very active efforts in both experiments and theory. QCD factorization has been carefully studied. A SIDIS experiment on the neutron with a polarized 3 He target was performed at JLab. Recently published results will be shown. Precision TMD experiments are planned at JLab after the 12 GeV energy upgrade. The approved experiments with a new SoLID spectrometer on both the proton and neutron will be presented. Proper QCD evolution treatments beyond collinear cases become crucial for the precision study of the TMDs. Experimentally, Q2 evolution and higher-twist effects are often closely related. The experience of study higher-twist effects in the cases of moments of the spin structure functions will be discussed.
DEFINITION AND EVOLUTION OF TRANSVERSE MOMENTUM DISTRIBUTIONS
Authors: ECHEVARRÍA MIGUEL G. , IDILBI AHMAD , SCIMEMI IGNAZIO
Published: December 2012

We consider the definition of unpolarized transverse-momentum-dependent parton distribution functions while staying on-the-light-cone. By imposing a requirement of identical treatment of two collinear sectors, our approach, compatible with a generic factorization theorem with the soft function included, is valid for all non-ultra-violet regulators (as it should), an issue which causes much confusion in the whole field. We explain how large logarithms can be resummed in a way which can be considered as an alternative to the use of Collins-Soper evolution equation. The evolution properties are also discussed and the gauge-invariance, in both classes of gauges, regular and singular, is emphasized.
PHENOMENOLOGY OF THE SIVERS EFFECT WITH TMD EVOLUTION
Authors: ANSELMINO M. , BOGLIONE M. , MELIS S.
Published: December 2012

Recently, theoretical developments have led to the QCD evolution equations for the unpolarized Transverse Momentum Dependent (TMD) distribution functions and for the Sivers function (TMD-evolution). We tested whether the proposed TMD-evolution can already be observed in the SIDIS data on the Sivers asymmetry. Although very preliminary, our analysis shows that data are compatible with such an evolution with a clear indication of evolution in the x-dependent data subsets.
TRANSVERSE MOMENTUM-DEPENDENT PARTON DISTRIBUTIONS FROM LATTICE QCD
Authors: ENGELHARDT M. , MUSCH B. , HÄGLER P. , NEGELE J. , SCHÄFER A.
Published: December 2012

Starting from a definition of transverse momentum-dependent parton distributions for semi-inclusive deep inelastic scattering and the Drell-Yan process, given in terms of matrix elements of a quark bilocal operator containing a staple-shaped Wilson connection, a scheme to determine such observables in lattice QCD is developed and explored. Parametrizing the aforementioned matrix elements in terms of invariant amplitudes permits a simple transformation of the problem to a Lorentz frame suited for the lattice calculation. Results for the Sivers and Boer-Mulders transverse momentum shifts are presented, focusing in particular on their dependence on the staple extent and the Collins-Soper evolution parameter.
PHOTON IMPACT FACTOR AND kT FACTORIZATION IN THE NEXT-TO-LEADING ORDER
Authors: BALITSKY IAN
Published: December 2012

The photon impact factor for the BFKL pomeron is calculated in the next-to-leading order (NLO) approximation using the operator expansion in Wilson lines. The result is represented as a NLO kT-factorization formula for the structure functions of small-x deep inelastic scattering.
THE NLO INCLUSIVE FORWARD HADRON PRODUCTION IN pA COLLISIONS
Authors: CHIRILLI GIOVANNI , XIAO BO-WEN , YUAN FENG
Published: December 2012

Recently, by performing the complete next-to-leading order calculation, we have demonstrated the one-loop factorization for inclusive hadron productions in pA collisions in the saturation formalism. The differential cross section is written into a factorization form in the coordinate space at the next-to-leading order, while the naive form of the convolution in the transverse momentum space does not hold. The rapidity divergence with small-x dipole gluon distribution of the nucleus is factorized into the energy evolution of the dipole gluon distribution function, which is known as the Balitsky-Kovchegov equation. Furthermore, the collinear divergences associated with the incoming parton distribution of the nucleon and the outgoing fragmentation function of the final state hadron are factorized into the splittings of the associated parton distribution and fragmentation functions, which allows us to reproduce the well-known DGLAP equation. The hard coefficient function, which is finite and free of divergence of any kind, is evaluated at one-loop order. This result is important, not only for the phenomenological applications to the inclusive hadron production in p-A collisions at RHIC and future LHC experiment, but also for theoretically promoting the rigorous developments towards a complete QCD factorization in small-x physics.
GENERALIZED PARTON DISTRIBUTIONS IN THE CHIRAL ODD SECTOR AND THEIR ROLE IN NEUTRAL MESON ELECTROPRODUCTION
Authors: GOLDSTEIN GARY R. , LIUTI SIMONETTA , GONZALEZ-HERNANDEZ J. OSVALDO
Published: December 2012

Our original suggestion to investigate exclusive π0 electroproduction as a method for extracting from data the tensor charge, transversity, and other quantities related to chiral odd generalized parton distributions is further examined. We now explain the details of the process: i) the connection between the helicity description and the cartesian basis; ii) the dependence on the momentum transfer squared, Q2, and iii) the angular momentum, parity, and charge conjugation constraints (JPC quantum numbers).
Contribution of FcRn binding to intestinal uptake of IgG in suckling rat pups and human FcRn-transgenic mice
Authors: Kliwinski C. , Cooper P. R. , Perkinson R. , Mabus J. R. , Tam S. H. , Wilkinson T. M. , Giles-Komar J. , Scallon B. , Powers G. D. , Hornby P. J.
Published: December 2012

Immunoglobulin G (IgG) is transcytosed across intestinal epithelial cells of suckling mammals by the neonatal Fc receptor (FcRn); however, the contribution of FcRn vs. FcRn-independent uptake to serum IgG levels had not been determined in either rat pups or human (h)FcRn-expressing mice (Tg276 and Tg32). In isoflurane-anesthetized rodents, serum levels were determined after regional intestinal delivery of human monoclonal antibodies (hIgG) with either wild-type (WT) Fc sequences or variants engineered for different FcRn binding affinities. Detection of full-length hIgG was by immunoassay; intestinal hFcRn and hIgG localization was by immunocytochemistry. High (μg/ml) serum levels of hIgG were detected after proximal intestinal delivery (0.1–10 mg/kg) in 2-wk-old rats. Human FcRn was visualized in epithelial cells of Tg276 mice, but low serum hIgG levels (<10 ng/ml) were obtained. In rat pups, intraintestinal hIgG1 WT administration resulted in dose-related and saturable uptake, whereas uptake of a low FcRn-binding affinity variant was nonsaturable. There were no differences in hIgG levels from systemic and hepatic portal vein serum samples, and intense hIgG immunostaining was noted in villi enterocytes and within lymphatic lacteal-like vessels. This study demonstrated that FcRn-mediated uptake in rat pups accounted for ∼80% of serum hIgG levels and that IgG enters the circulation via the lymph and not the hepatic portal vein. The remaining uptake though the immature intestine is nonreceptor mediated. Intestinal epithelial cell hFcRn expression occurred in Tg276 mice, but receptor-mediated transport of IgG was not observed. The suckling rat pup intestine is a mechanistic model of FcRn-IgG-mediated transcytosis.
Pulmonary blood flow and its distribution in highly trained endurance athletes and healthy control subjects
Authors: Heinonen Ilkka , Savolainen Anna M. , Han Chunlei , Kemppainen Jukka , Oikonen Vesa , Luotolahti Matti , Duncker Dirk J. , Merkus Daphne , Knuuti Juhani , Kalliokoski Kari K.
Published: December 2012

Pulmonary blood flow (PBF) is an important determinant of endurance sports performance, yet studies investigating adaptations of the pulmonary circulation in athletes are scarce. In the present study, we investigated PBF, its distribution, and heterogeneity at baseline and during intravenous systemic adenosine infusion in 10 highly trained male endurance athletes and 10 untrained but fit healthy controls, using positron emission tomography and [15O]water at rest and during adenosine infusion at supine body posture. Our results indicate that PBF at rest and during adenosine stimulation was similar in both groups (213 ± 55 and 563 ± 138 ml·100 ml−1·min−1in athletes and 206 ± 83 and 473 ± 212 ml·100 ml−1·min−1in controls, respectively). Although the PBF response to adenosine was thus unchanged in athletes, overall PBF heterogeneity was reduced from rest to adenosine infusion (from 84 ± 18 to 70 ± 19%, P < 0.05), while remaining unchanged in healthy controls (77 ± 16 to 85 ± 33%, P = 0.4). Additionally, there was a marked gravitational influence on general PBF distribution so that clear dorsal dominance was observed both at rest and during adenosine infusion, but training status did not have an effect on this distribution. Regional blood flow heterogeneity was markedly lower in the high-perfusion dorsal areas, both at rest and during adenosine, in all subjects, but flow heterogeneity in dorsal area tended to further decrease in response to adenosine in athletes. In conclusion, reduced blood flow heterogeneity in response to adenosine in endurance athletes may be a reflection of capillary reserve, which is more extensively recruitable in athletes than in matched healthy control subjects.
Mitochondria express enhanced quality as well as quantity in association with aerobic fitness across recreationally active individuals up to elite athletes
Authors: Jacobs Robert A. , Lundby Carsten
Published: December 2012

Changes in skeletal muscle respiratory capacity parallel that of aerobic fitness. It is unknown whether mitochondrial content, alone, can fully account for these differences in skeletal muscle respiratory capacity. The aim of the present study was to examine quantitative and qualitative mitochondrial characteristics across four different groups ( n = 6 each), separated by cardiorespiratory fitness. High-resolution respirometry was performed on muscle samples to compare respiratory capacity and efficiency in active, well-trained, highly trained, and elite individuals. Maximal exercise capacity (ml O2·min−1·kg−1) differed across all groups, with mean ± SD values of 51 ± 4, 64 ± 5, 71 ± 2, and 77 ± 3, respectively. Mitochondrial content assessed by citrate synthase activity was higher in elite trained compared with active and well-trained (29 ± 7 vs. 16 ± 4 and 19 ± 4 nmol·min−1·mg wet wt−1, respectively). When normalizing respiration to mitochondrial content, the respiratory capacities during maximal fatty acid oxidation ( P = 0.003), maximal state 3 respiration ( P = 0.021), and total electron transport system capacity ( P = 0.008) improved with respect to maximal exercise capacity. The coupling efficiency of β-oxidation, however, expressed no difference across groups. These data demonstrate the quantitative and qualitative differences that exist in skeletal muscle mitochondrial respiratory capacity and efficiency across individuals that differ in aerobic capacity. Mitochondrial-specific respiration capacities during β-oxidation, maximal oxidative phosphorylation, and electron transport system capacity all correspondingly improve with aerobic capacity, independent of mitochondrial content in human skeletal muscle.
Activation of proteases and changes in Na+-K+-ATPase subunits in hearts subjected to ischemia-reperfusion
Authors: Müller Alison L. , Freed Darren , Dhalla Naranjan S.
Published: December 2012

Previous studies have shown that ischemia-reperfusion (I/R) injury is associated with cardiac dysfunction and changes in sarcolemmal Na+-K+-ATPase subunits and activity. This study was undertaken to evaluate the role of proteases in these alterations by subjecting rat hearts to different times of global ischemia, as well as reperfusion after 45 min of ischemia. Decreases in Na+-K+-ATPase activity at 30–60 min of global ischemia were accompanied by augmented activities of both calpain and matrix metalloproteinases (MMPs) and depressed protein content of β1- and β2-subunits, without changes in α1- and α2-subunits of the enzyme. Compared with control values, the activities of both calpain and MMP-2 were increased, whereas the activity and protein content for all subunits of Na+-K+-ATPase were decreased upon reperfusion for 5–40 min, except that α1- and α2-subunit content was not depressed in 5 min I/R hearts. MDL28170, a calpain inhibitor, was more effective in attenuating the I/R-induced alterations in cardiac contracture, Na+-K+-ATPase activity, and α2-subunit than doxycycline, an MMP inhibitor. Incubation of control sarcolemma preparation with calpain, unlike MMP-2, depressed Na+-K+-ATPase activity and decreased α1-, α2-, and β2-subunits, without changes in the β1-subunit. These results support the view that activation of both calpain and MMP-2 are involved in depressing Na+-K+-ATPase activity and degradation of its subunits directly or indirectly in hearts subjected to I/R injury.