bluuebunny/crossref_metadata_2025 huggingface dataset:
Polarization bremsstrahlung spectrum of xenon clusters: detection of the contribution of collective interactions
Authors: Gnatchenko E. V. , Nechaĭ A. N. , Samovarov V. N. , Tkachenko A. A.
Published: March 2010

The first experimental investigations of polarization bremsstrahlung (PB) spectra accompanying the scattering of 0.7keV electrons by solid xenon clusters for photon energies 80–180eV are reported. Changes have been detected in the spectrum at the transition from the gaseous to the condensed phase of xenon. The maximum of the PB band shifts into the low-energy range and the spectral contour of the band narrows. Model calculations of the PB for xenon clusters are in good agreement with the spectral changes observed experimentally. Collective effects in the solid are found to have a large effect on the PB spectrum.
Homogeneous distribution of carriers in the conducting planes by Zn substitution at Cu sites in Cu0.5Tl0.5Ba2Ca3Cu4O12−δ superconductors
Authors: Mumtaz M. , Khan Nawazish A.
Published: March 2010

The effect of antiferromagnetic order suppression and charge stripes formation by Zn3d10 (S=0) substitution at Cu3d9 (S=1∕2) sites in CuO2 planes of Cu0.5Tl0.5Ba2Ca3Cu4O12−δ on the superconductivity parameters is demonstrated. If antiferromagnetism and charge stripes have some role in bringing about superconductivity at a particular temperature, doping with nonmagnetic Zn impurity would destroy it and hence the superconductivity. However we have observed enhanced superconducting properties with increased Zn doping in Cu0.5Tl0.5Ba2Ca3Cu4O12−δ superconductor. The decreased c-axis length with increased Zn doping improves interlayer coupling and hence the three-dimensional conductivity in the unit cell. The role of charge carriers in CuO2 planes of Cu0.5Tl0.5Ba2Ca3Cu4−yZnyO12−δ in bringing about superconductivity has also been explained.
Superconductivity without dependence on valence electron density in (Al, Zn, Co) doped YBCO systems
Authors: Yufeng Zhang , Dandan Wang , Pinglin Li
Published: March 2010

We have used x-ray diffraction, oxygen content, positron annihilation technology, and simulation methods to investigate systematically the cuprates YBa2Cu3−x(Al,Zn,Co)xO7−δ (x=0–0.5). The experimental results and simulation calculations support the existence of a cluster effect. Moreover, it is concluded that the cluster effect is an important factor in the suppression of superconductivity and that Tc does not depend directly on the valence electron density in the samples.
Evidence of s-wave subdominant order parameter in YBa2Cu3O7−δ from break-junction tunneling spectra
Authors: Akimenko A. I. , Bobba F. , Giubileo F. , Gudimenko V. A. , Piano S. , Cucolo A. M.
Published: March 2010

The tunneling spectra of YBa2Cu3O7−δ break junctions have been investigated for tunneling close to the node direction. The behavior of the zero-bias conductance peak (ZBCP) and the Josephson current have been studied as a function of the temperature and magnetic field. The deep splitting of the ZBCP is observed starting at TS<20–30K in agreement with the dx2−y2±is order parameter theory [Y. Tanuma, Y. Tanaka, S. Kashiwaya, Phys. Rev. B 64, 214519 (2001)]. We have observed that a low (0.04T) magnetic field significantly suppresses such splitting. The 1∕T temperature dependence of the maximum Josephson current going to saturation at T<TS also confirms mixed order parameter formation.
Melting point and phase diagram of methanol as obtained from computer simulations of the OPLS model
Authors: Gonzalez Salgado D. , Vega C.
Published: March 2010

In this work, the melting point and the phase diagram of methanol is determined via computer simulations using the OPLS model. The three different solid structures that are found experimentally were considered. By computing the free energies of both the fluid phase and the three different solid structures (α,β,γ), the initial solid-solid and fluid-solid coexistence points were determined. By performing Gibbs–Duhem integration, the complete coexistence lines were evaluated. In this way, it was possible to compute, for the first time, the complete phase diagram for a potential model of methanol. It is found that the optimized potential model for liquid simulations (OPLS) provides reasonable predictions for the densities of the three solid polymorphs, although they tend to be somewhat low when compared with the experiment. Overall the model provides a qualitatively correct description of the phase diagram of methanol. The β solid, which is thermodynamically stable in the experimental phase diagram of methanol, is found to be metastable in the phase diagram of the model. The α phase is stable at low pressures and the γ phase is stable at high pressures, in agreement with experiment. Thus, the model is able to predict the existence of the γ solid at high pressure. From free energy calculations we found that the melting point of the model at room pressure is 215 K. That was further confirmed by direct coexistence simulations. Thus, the model presents a melting point about 40 K above the experimental value of 175 K. Thus the OPLS model provides a reasonable description of the phase diagram of methanol, but it could probably be modified to improve the phase diagram predictions.
Kinetics of catalyst size dependent carbon nanotube growth by growth interruption studies
Authors: Patole S. P. , Kim Hyeongkeun , Choi Jaeboong , Kim Youngjin , Baik Seunghyun , Yoo J. B.
Published: March 2010

The dependence of the growth kinetics of carbon nanotubes (CNTs) on the size of the Fe-catalyst in the H2 assisted atmospheric pressure chemical vapor deposition was studied. A growth interruption method was used to determine the in situ growth rate. The formation of a compact scale contaminant layer around the catalyst hinders the diffusion of the reactant species required to grow the CNTs. The high temperature metal oxidation behavior observed using parabolic curve fitting was attributed to the size dependent catalyst activity. The parabolic rate constant shows linear dependence on the catalyst size. Details of the analysis are presented.
Second-order electron-correlation and self-consistent spin-orbit treatment of heavy molecules at the basis-set limit
Authors: Bischoff Florian A. , Klopper Wim
Published: March 2010

Second-order perturbation theory using explicitly correlated wave functions has been introduced into a quasirelativistic two-component formalism. The convergence of the correlation energy is as much improved as for the nonrelativistic Hamiltonian, achieving basis-set-limit results in a moderate-size basis set. Equilibrium distances and vibrational frequencies of small molecules of the 6th period of the periodic system of the elements have been calculated, demonstrating the improved behavior of the explicitly correlated wave functions. Taking advantage of density-fitting techniques, the explicitly correlated approach is an economical and appealing alternative to conventional two-component second-order perturbation theory in a large one-particle basis.
Real-time x-ray response of biocompatible solution gate AlGaN/GaN high electron mobility transistor devices
Authors: Hofstetter Markus , Howgate John , Sharp Ian D. , Funk Maren , Stutzmann Martin , Paretzke Herwig G. , Thalhammer Stefan
Published: March 2010

We present the real-time x-ray irradiation response of charge and pH sensitive solution gate AlGaN/GaN high electron mobility transistors. The devices show stable and reproducible behavior under and following x-ray radiation, including a linear integrated response with dose into the μGy range. Titration measurements of devices in solution reveal that the linear pH response and sensitivity are not only retained under x-ray irradiation, but an irradiation response could also be measured. Since the devices are biocompatible, and can be simultaneously operated in aggressive fluids and under hard radiation, they are well-suited for both medical radiation dosimetry and biosensing applications.
Study of molecular dynamics of the pharmaceutically important protic ionic liquid verapamil hydrochloride. II. Test of entropic models
Authors: Wojnarowska Z. , Grzybowska K. , Grzybowski A. , Paluch M. , Kaminski K. , Wlodarczyk P. , Adrjanowicz K. , Pionteck J.
Published: March 2010

In this work we analyzed the structural relaxation times as a function of both temperature and pressure in terms of the entropic models by using dielectric and PVT measurements data presented in our previous research on the ionic liquid verapamil hydrochloride [Z. Wojnarowska, M. Paluch, A. Grzybowski, et al., J. Chem. Phys. 131, 104505 (2009)]. Two different approaches were used to analyze the τα(T,P) dependence: the modified Avramov model as well as the pressure extended Adam–Gibbs model in the forms proposed by Casalini (AGC) and Schwartz (AGS). In every case a satisfactory description of the structural relaxation times was achieved. Additionally, using both mentioned models the pressure dependence of the fragility mP and the glass transition temperature Tg were determined. We also compared the value of dTg/dP∣P=0 calculated on the basis of the considered entropic models with the experimental value evaluated in our recent work. Consequently, we were able to estimate which of the examined models in the best way relates the dynamic to the thermodynamic parameters.
Charge trapping properties of the HfO2 layer with various thicknesses for charge trap flash memory applications
Authors: You Hee-Wook , Cho Won-Ju
Published: March 2010

MHOS (metal-HfO2–SiO2–Si) structure capacitors were fabricated to investigate the charge trapping properties of HfO2 layer with various thicknesses for the applications of charge trap flash (CTF) memory devices. Also, the centroid of charge trap in HfO2 layer was extracted by constant current stress method and compared with that of conventional Si3N4 layer. The gate leakage current of MHOS capacitor due to tunneling was significantly reduced by stacking the HfO2 trap layer on thin SiO2 tunnel layer. The MHOS capacitors showed a larger memory window than the MNOS (metal-Si3N4–SiO2–Si) capacitors at the same trap layer thickness, because the HfO2 layer has better charge trapping efficiency than the Si3N4 layer. It is found that ultrathin HfO2 trap layer with a thickness of 2 nm stored almost the same charges with Si3N4 layer with a thickness of 7 nm. Consequently, the application of ultrathin HfO2 to charge storage layer can considerably improve the performance and enhance the high density of CTF memory.
Junction properties of Au/ZnO single nanowire Schottky diode
Authors: Das Sachindra Nath , Choi Ji-Huck , Kar Jyoti Prakash , Moon Kyeong-Ju , Lee Tae Il , Myoung Jae-Min
Published: March 2010

In this study, we have analyzed the Au/ZnO single nanowire based Schottky diode by investigating temperature dependent current voltage and x-ray photoelectron spectroscopy (XPS) measurements. The calculated barrier height of the Schottky diodes by using the thermionic emission model is in good agreement with the value obtained from the XPS measurements but lower than the theoretically predicted value. The ionization of interface states has been considered for explaining this discrepancy.
Carrier transport in strained p-channel field-effect transistors with diamondlike carbon liner stressor
Authors: Cheng Ran , Liu Bin , Yeo Yee-Chia
Published: March 2010

We report the investigation of carrier backscattering characteristics of compressively strained p-channel field-effect transistors (p-FETs) with diamondlike carbon (DLC) liner stressor. p-FETs strained by the DLC liner exhibit up to ∼40% enhancement in carrier injection velocity υinj. However, a slight reduction in ballistic efficiency Bsat is also observed in the DLC stressed p-FETs. Despite the Bsat degradation, an overall boost in saturation drive current IDsat is achieved. For a DLC stressed p-FET with gate length LG=90 nm, a ∼36% enhancement in IDsat is observed with a ∼40% improvement in υinj. The dependence of IDsat on υinj and carrier mobility μ is also discussed in this letter.
Ultrathin Cu-Ti bilayer transparent conductors with enhanced figure-of-merit and stability
Authors: Ghosh D. S. , Chen T. L. , Pruneri V.
Published: March 2010

We propose a transparent conductor (TC) structure based on the combination of ultrathin Cu and Ti films. The conductive Cu layer becomes continuous, i.e., it reaches the percolation threshold, for thicknesses in the range of 5.5–6.5 nm. However, without any adequate countermeasure, such an ultrathin layer would unavoidably oxidize even at ambient conditions. In this letter, we show that Ti capping layer in situ treated by oxygen plasma can protect the underlying Cu ultrathin layer and enhances its figure-of-merit. The improved optical properties can be attributed to multiple reflection and refraction effects in Cu-Ti bilayer system. The obtained Cu-Ti bilayer ultrathin films show transparency of 86% at wavelengths around 630 nm and sheet resistance of 16 Ω/sq, and exhibit excellent stability, as demonstrated by the fact that their properties do not significantly change after thermal treatment up to 120 °C for a dwell time of 45 min in ambient atmosphere.
Capacitive-type counter of nanoparticles in air
Authors: Iskra I. , Detela A. , Viršek M. , Nemanič V. , Križaj D. , Golob D. , van Elteren J. T. , Remškar M.
Published: March 2010

A capacitive-type counter of nanoparticles in air, based on measurement of the capacitance of a capacitor with a variable dielectric part, has been developed. The method is suitable for detection of aerosols in a wide concentration range, regardless of shape or chemical composition. The method is demonstrated experimentally and verified by numerical simulations. The counter allows for construction of a simple, portable, and cheap nanoparticle detector for air quality control.
As doping of Si-based low-dimensional systems
Authors: Ruffino F. , Tomasello M. V. , Miritello M. , Nicotra G. , Spinella C. , Grimaldi M. G.
Published: March 2010

In this work we studied the As redistribution in SiO2(70 nm)/Si(30 nm)/SiO2(70 nm) multilayer during postimplantation annealing. By Rutherford backscattering spectrometry and Z-contrast transmission electron microscopy we found an As accumulation at the Si/SiO2 interfaces and at the Si grain boundaries with no segregation of the As in the Si layer. Such an effect could be qualitatively in agreement with a model that assumes a traps distribution into the Si in the first 2–3 nm above the SiO2/Si interfaces and along the Si grain boundaries. In particular, the traps concentration at the Si/SiO2 interfaces was estimated in 1014 traps/cm2.
Technique to improve performance of Al2O3 interpoly dielectric using a La2O3 interface scavenging layer for floating gate memory structures
Authors: Jayanti Srikant , Yang Xiangyu , Lichtenwalner Daniel J. , Misra Veena
Published: March 2010

A technique of scavenging the SiO2 interfacial layer (IL) to improve the electrical performance of Al2O3 as the interpoly dielectric for flash memories has been studied. Scavenging was performed by the reaction of a thin La2O3 layer with the native oxide to form a high-κ lanthanum silicate. Significant improvement in the charge trapping and leakage characteristics were obtained. Transmission electron microscopy analysis was done to corroborate the electrical results. Results show that seven orders of magnitude leakage reduction was achieved by the replacement of the SiO2 IL with a higher-κ dielectric LaSiO at the Si interface.
SSR allelic diversity in relation to morphological traits and resistance to grain mould in sorghum
Authors: Sharma Rajan , Deshpande S. P. , Senthilvel S. , Rao V. P. , Rajaram V. , Hash C. T. , Thakur R. P.
Published: March 2010

Allelic variation at 46 simple sequence repeat (SSR) marker loci well distributed across the sorghum genome was used to assess genetic diversity among 92 sorghum lines, 74 resistant and 18 susceptible to grain mould. Of the 46 SSR markers, 44 were polymorphic, with the number of alleles ranging from 2 to 20 with an average of 7.55 alleles per locus. Genetic diversity among the sorghum lines was high as indicated by polymorphic information content (PIC) and gene diversity values. PIC values of polymorphic SSR markers ranged from 0.16 to 0.90, with an average of 0.54. Gene diversity among the sorghum lines varied from 0.16 to 0.91, with an average score of 0.58 per SSR marker. AMOVA indicated that 12% of the total variation observed among the sorghum lines was accounted for between grain mould resistant and susceptible types. Diversity based on six morphological traits and grain mould scores indicated major roles of panicle type and glumes coverage, followed by grain colour, in clustering of the lines. Seven grain mould resistant/susceptible pairs with dissimilarity indices >0.50, but with similar flowering time, plant height, and panicle type/inflorescence within each pair, were selected for use in developing recombinant inbred line mapping populations to identify genomic regions (and quantitative trait loci) associated with sorghum grain mould resistance.
Modularity of the Hrd1 ERAD complex underlies its diverse client range
Authors: Kanehara Kazue , Xie Wei , Ng Davis T.W.
Published: March 2010

Secretory protein folding is monitored by endoplasmic reticulum (ER) quality control mechanisms. Misfolded proteins are retained and targeted to ER-associated degradation (ERAD) pathways. At their core are E3 ubiquitin ligases, which organize factors that recognize, ubiquitinate, and translocate substrates. Of these, we report that the Hrd1 complex manages three distinct substrate classes. A core complex is required for all classes and is sufficient for some membrane proteins. The accessory factors Usa1p and Der1p adapt the complex to process luminal substrates. Their integration is sufficient to process molecules bearing glycan-independent degradation signals. The presence of Yos9p extends the substrate range by mediating the recognition of glycan-based degradation signals. This modular organization enables the Hrd1 complex to recognize topologically diverse substrates. The Hrd1 system does not directly evaluate the folding state of polypeptides. Instead, it does so indirectly, by recognizing specific embedded signals displayed upon misfolding.
ATR suppresses telomere fragility and recombination but is dispensable for elongation of short telomeres by telomerase
Authors: McNees Carolyn J. , Tejera Agueda M. , Martínez Paula , Murga Matilde , Mulero Francisca , Fernandez-Capetillo Oscar , Blasco Maria A.
Published: March 2010

Telomere shortening caused by incomplete DNA replication is balanced by telomerase-mediated telomere extension, with evidence indicating that the shortest telomeres are preferred substrates in primary cells. Critically short telomeres are detected by the cellular DNA damage response (DDR) system. In budding yeast, the important DDR kinase Tel1 (homologue of ATM [ataxia telangiectasia mutated]) is vital for telomerase recruitment to short telomeres, but mammalian ATM is dispensable for this function. We asked whether closely related ATR (ATM and Rad3 related) kinase, which is important for preventing replicative stress and chromosomal breakage at common fragile sites, might instead fulfill this role. The newly created ATR-deficient Seckel mouse strain was used to examine the function of ATR in telomerase recruitment and telomere function. Telomeres were recently found to resemble fragile sites, and we show in this study that ATR has an important role in the suppression of telomere fragility and recombination. We also find that wild-type ATR levels are important to protect short telomeres from chromosomal fusions but do not appear essential for telomerase recruitment to short telomeres in primary mouse embryonic fibroblasts from the ATR-deficient Seckel mouse model. These results reveal a previously unnoticed role for mammalian ATR in telomere protection and stability.
The Satake isomorphism for special maximal parahoric Hecke algebras
Authors: Haines Thomas , Rostami Sean
Published: March 2010

Let

G
G

denote a connected reductive group over a nonarchimedean local field

F
F

. Let

K
K

denote a special maximal parahoric subgroup of

G
(
F
)

G(F)

. We establish a Satake isomorphism for the Hecke algebra

H

K

\mathcal {H}_K

of

K
K

-bi-invariant compactly supported functions on

G
(
F
)

G(F)

. The key ingredient is a Cartan decomposition describing the double coset space

K
∖
G
(
F
)

/

K

K\backslash G(F)/K

. As an application we define a transfer homomorphism
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="t colon script upper H Subscript upper K Sub Superscript asterisk Subscript Baseline left-parenthesis upper G Superscript asterisk Baseline right-parenthesis right-arrow script upper H Subscript upper K Baseline left-parenthesis upper G right-parenthesis">

t
:

H

K
∗

(

G
∗

)
→

H

K

(
G
)

t: \mathcal {H}_{K^*}(G^*) \rightarrow \mathcal {H}_K(G)

where

G
∗

G^*

is the quasi-split inner form of

G
G

. We also describe how our results relate to the treatment of Cartier [Car], where

K
K

is replaced by a special maximal compact open subgroup

K
~

⊂
G
(
F
)

\widetilde {K} \subset G(F)

and where a Satake isomorphism is established for the Hecke algebra

H

K
~

\mathcal {H}_{\widetilde {K}}

.
Compressibility effects in Rayleigh–Taylor instability-induced flows
Authors: Gauthier S. , Le Creurer B.
Published: March 2010

We present a tentative review of compressibility effects in Rayleigh–Taylor instability-induced flows. The linear, nonlinear and turbulent regimes are considered. We first make the classical distinction between the static compressibility or stratification, and the dynamic compressibility owing to the finite speed of sound. We then discuss the quasi-incompressible limits of the Navier–Stokes equations (i.e. the low-Mach number, anelastic and Boussinesq approximations). We also review some results about stratified compressible flows for which instability criteria have been derived rigorously. Two types of modes, convective and acoustic, are possible in these flows. Linear stability results for perfect fluids obtained from an analytical approach, as well as viscous fluid results obtained from numerical approaches, are also reviewed. In the turbulent regime, we introduce Chandrasekhar’s observation that the largest structures in the density fluctuations are determined by the initial conditions. The effects of compressibility obtained by numerical simulations in both the nonlinear and turbulent regimes are discussed. The modifications made to statistical models of fully developed turbulence in order to account for compressibility effects are also treated briefly. We also point out the analogy with turbulent compressible Kelvin–Helmholtz mixing layers and we suggest some lines for further investigations.
Lagrangian views on turbulent mixing of passive scalars
Authors: Sreenivasan Katepalli R. , Schumacher Jörg
Published: March 2010

The Lagrangian view of passive scalar turbulence has recently produced interesting results and interpretations. Innovations in theory, experiments, simulations and data analysis of Lagrangian turbulence are reviewed here in brief. Part of the review is closely related to the so-called Kraichnan model for the advection of the passive scalar in synthetic turbulence. Possible implications for a better understanding of the passive scalar mixing in Navier–Stokes turbulence are also discussed.
Mechanisms for magnetic field reversals
Authors: Pétrélis F. , Fauve S.
Published: March 2010

We present a review of the different models that have been proposed to explain reversals of the magnetic field generated by a turbulent flow of an electrically conducting fluid (fluid dynamos). We then describe a simple mechanism that explains several features observed in palaeomagnetic records of the Earth’s magnetic field, in numerical simulations and in a recent dynamo experiment. A similar model can also be used to understand reversals of large-scale flows that often develop on a turbulent background.
Richtmyer–Meshkov instability: theory of linear and nonlinear evolution
Authors: Nishihara K. , Wouchuk J. G. , Matsuoka C. , Ishizaki R. , Zhakhovsky V. V.
Published: March 2010

A theoretical framework to study linear and nonlinear Richtmyer–Meshkov instability (RMI) is presented. This instability typically develops when an incident shock crosses a corrugated material interface separating two fluids with different thermodynamic properties. Because the contact surface is rippled, the transmitted and reflected wavefronts are also corrugated, and some circulation is generated at the material boundary. The velocity circulation is progressively modified by the sound wave field radiated by the wavefronts, and ripple growth at the contact surface reaches a constant asymptotic normal velocity when the shocks/rarefactions are distant enough. The instability growth is driven by two effects: an initial deposition of velocity circulation at the material interface by the corrugated shock fronts and its subsequent variation in time due to the sonic field of pressure perturbations radiated by the deformed shocks. First, an exact analytical model to determine the asymptotic linear growth rate is presented and its dependence on the governing parameters is briefly discussed. Instabilities referred to as RM-like, driven by localized non-uniform vorticity, also exist; they are either initially deposited or supplied by external sources. Ablative RMI and its stabilization mechanisms are discussed as an example. When the ripple amplitude increases and becomes comparable to the perturbation wavelength, the instability enters the nonlinear phase and the perturbation velocity starts to decrease. An analytical model to describe this second stage of instability evolution is presented within the limit of incompressible and irrotational fluids, based on the dynamics of the contact surface circulation. RMI in solids and liquids is also presented via molecular dynamics simulations for planar and cylindrical geometries, where we show the generation of vorticity even in viscid materials.
High-performance holographic technologies for fluid-dynamics experiments
Authors: Orlov Sergei S. , Abarzhi Snezhana I. , Oh Se Baek , Barbastathis George , Sreenivasan Katepalli R.
Published: March 2010

Modern technologies offer new opportunities for experimentalists in a variety of research areas of fluid dynamics. Improvements are now possible in the state-of-the-art in precision, dynamic range, reproducibility, motion-control accuracy, data-acquisition rate and information capacity. These improvements are required for understanding complex turbulent flows under realistic conditions, and for allowing unambiguous comparisons to be made with new theoretical approaches and large-scale numerical simulations.

One of the new technologies is high-performance digital holography. State-of-the-art motion control, electronics and optical imaging allow for the realization of turbulent flows with very high Reynolds number (more than 107) on a relatively small laboratory scale, and quantification of their properties with high space–time resolutions and bandwidth. In-line digital holographic technology can provide complete three-dimensional mapping of the flow velocity and density fields at high data rates (over 1000 frames per second) over a relatively large spatial area with high spatial (1–10 μm) and temporal (better than a few nanoseconds) resolution, and can give accurate quantitative description of the fluid flows, including those of multi-phase and unsteady conditions. This technology can be applied in a variety of problems to study fundamental properties of flow–particle interactions, rotating flows, non-canonical boundary layers and Rayleigh–Taylor mixing. Some of these examples are discussed briefly.
Toll‐like receptor 4 D299G polymorphism and the incidence of infections in cirrhotic patients
Authors: GUARNER‐ARGENTE C. , SÁNCHEZ E. , VIDAL S. , ROMÁN E. , CONCEPCIÓN M. , POCA M. , SÁNCHEZ D. , JUÁREZ C. , SORIANO G. , GUARNER C.
Published: March 2010

Aliment Pharmacol Ther 31, 1192–1199

Background  Toll‐like receptor (TLR) 4 genetic polymorphisms, mainly D299G, have been associated with increased predisposition to infection in several populations.

Aim  To retrospectively analyse the relationship between the presence of the TLR4 D299G polymorphism and the incidence of bacterial infections in cirrhotic patients.

Methods  We included 111 consecutive cirrhotic patients hospitalized with ascites and we determined the presence of the TLR4 D299G polymorphism by PCR–RFLP (polymerase chain reaction–restriction fragment length polymorphism) and its relationship with the incidence of previous bacterial infections.

Results  Ten out of 111 (9%) cirrhotic patients presented with the TLR4 D299G polymorphism. The mean follow‐up from first decompensation of cirrhosis until current admission was longer in D299G polymorphism patients than in wild‐type patients (53.8 ± 40.7 vs. 35.4 ± 48.3 months, P = 0.03). D299G polymorphism patients showed a trend towards a higher incidence of history of previous infections (80% vs. 56.4%, P = 0.19), as well as a higher number of infections (2.8 ± 2.3 vs. 1.0 ± 1.3, P = 0.01) and bacteriaemias (0.4 ± 1.0 vs. 0.04 ± 0.2, P = 0.02) per patient than wild‐type patients.

Conclusions  Toll‐like receptor 4 D299G polymorphism could influence not only the predisposition to bacterial infections but also the evolution of the disease in cirrhotic patients. Further prospective studies in larger series of patients are warranted.
Trunk blocks for abdominal surgery
Authors: Finnerty O. , Carney J. , McDonnell J. G.
Published: March 2010

In this review, we discuss the central non‐neuraxial regional anaesthesia blocks of the abdomen, including intercostal and intrapleural blocks, rectus sheath and ilioinguinal‐iliohypogastric blocks, transversus abdominis plane blocks and paravertebral blocks.
Regional anaesthesia in day‐stay and short‐stay surgery
Authors: Kopp S. L. , Horlocker T. T.
Published: March 2010

The goals for ambulatory surgery are rapid recovery with minimal side effects, adequate postoperative pain control, rapid patient discharge and overall cost containment. The addition of regional anaesthetic techniques has been shown to decrease nausea, postoperative pain scores and the need for post‐anaesthesia care unit monitoring. The use of regional anaesthesia is increasing as studies confirm the goals for ambulatory anaesthesia can be met with a combination of regional anaesthesia and a multimodal pain management regimen.
Lower limb blocks
Authors: Murray J. M. , Derbyshire S. , Shields M. O.
Published: March 2010

The advances in regional techniques for blocks of the lower limb have been driven primarily by the need to produce effective analgesia in the postoperative period and beyond. These techniques are commonly performed before or after central neuraxial blockade when this technique is used to provide anaesthesia and analgesia for the surgical procedure. Increasingly, modern practice demands a shorter hospital stay, improved patient expectations and early mobilisation. This article describes the current methods and reasons for performing specific blocks to the lower limb and the management of these blocks particularly in the postoperative period.
Current trends in paediatric regional anaesthesia
Authors: Willschke H. , Marhofer P. , Machata A.‐M. , Lönnqvist P.‐A.
Published: March 2010

Regional anaesthesia is a cornerstone in paediatric anaesthesia today. Many paediatric anaesthetists include regional anaesthetic techniques in their daily clinical practice to provide superior and long‐lasting analgesia without the risk of respiratory depression. The first part this article reviews new scientific findings in the field of paediatric regional anaesthesia. The second part focuses on safety aspects and on the impact of ultrasound on paediatric regional anaesthesia.
Effect of eculizumab on haemolysis‐associated nitric oxide depletion, dyspnoea, and measures of pulmonary hypertension in patients with paroxysmal nocturnal haemoglobinuria
Authors: Hill Anita , Rother Russell P. , Wang Xunde , Morris, Jr Sidney M. , Quinn‐Senger Kerry , Kelly Richard , Richards Stephen J. , Bessler Monica , Bell Leonard , Hillmen Peter , Gladwin Mark T.
Published: March 2010

Pulmonary hypertension (PH) is a common complication of haemolytic anaemia. Intravascular haemolysis leads to nitric oxide (NO) depletion, endothelial and smooth muscle dysregulation, and vasculopathy, characterized by progressive hypertension. PH has been reported in patients with paroxysmal nocturnal haemoglobinuria (PNH), a life‐threatening haemolytic disease. We explored the relationship between haemolysis, systemic NO, arginine catabolism and measures of PH in 73 PNH patients enrolled in the placebo‐controlled TRIUMPH (Transfusion Reduction Efficacy and Safety Clinical Investigation Using Eculizumab in Paroxysmal Nocturnal Haemoglobinuria) study. At baseline, intravascular haemolysis was associated with elevated NO consumption (P < 0·0001) and arginase‐1 release (P < 0·0001). Almost half of the patients in the trial had elevated levels (≥160 pg/ml) of N‐terminal pro‐brain natriuretic peptide (NT‐proBNP), a marker of pulmonary vascular resistance and right ventricular dysfunction previously shown to indicate PH. Eculizumab treatment significantly reduced haemolysis (P < 0·001), NO depletion (P < 0·001), vasomotor tone (P < 0·05), dyspnoea (P = 0·006) and resulted in a 50% reduction in the proportion of patients with elevated NT‐proBNP (P < 0·001) within 2 weeks of treatment. Importantly, the significant improvements in dyspnoea and NT‐proBNP levels occurred without significant changes in anaemia. These data demonstrated that intravascular haemolysis in PNH produces a state of NO catabolism leading to signs of PH, including elevated NT pro‐BNP and dyspnoea that are significantly improved by treatment with eculizumab.
Lipid levels in sickle‐cell disease associated with haemolytic severity, vascular dysfunction and pulmonary hypertension
Authors: Zorca Suzana , Freeman Lita , Hildesheim Mariana , Allen Darlene , Remaley Alan T. , Taylor James G. , Kato Gregory J.
Published: March 2010

Pulmonary hypertension (PH) in sickle cell disease (SCD) is an emerging and important clinical problem. In a single‐institution adult cohort of 365 patients, we investigated lipid and lipoprotein levels and their relationship to markers of intravascular haemolysis, vascular dysfunction and PH. In agreement with prior studies, we confirm significantly decreased plasma levels of total cholesterol, high‐density lipoprotein‐cholesterol (HDL‐C) and low‐density lipoprotein‐cholesterol (LDL‐C) in SCD versus ethnically‐matched healthy controls. Several cholesterol parameters correlated significantly with markers of anaemia, but not endothelial activation or PH. More importantly, serum triglyceride levels were significantly elevated in SCD compared to controls. Elevated triglyceride levels correlated significantly with markers of haemolysis (lactate dehydrogenase and arginase; both P < 0·0005), endothelial activation (soluble E‐selectin, P < 0·0001; soluble P‐selectin, P = 0·02; soluble vascular cell adhesion molecule‐1, P = 0·01), inflammation (leucocyte count, P = 0·0004; erythrocyte sedimentation rate, P = 0·02) and PH (amino‐terminal brain natriuretic peptide, P = 0·002; prevalence of elevated tricuspid regurgitant velocity (TRV), P < 0·001). In a multivariate analysis, triglyceride levels correlated independently with elevated TRV (P = 0·002). Finally, forearm blood flow studies in adult patients with SCD demonstrated a significant association between increased triglyceride/HDL‐C ratio and endothelial dysfunction (P < 0·05). These results characterize elevated plasma triglyceride levels as a potential risk factor for PH in SCD.
Ant versus bird exclusion effects on the arthropod assemblage of an organic citrus grove
Authors: PIÑOL JOSEP , ESPADALER XAVIER , CAÑELLAS NÚRIA , MARTÍNEZ‐VILALTA JORDI , BARRIENTOS JOSÉ A. , SOL DANIEL
Published: March 2010

1. Predation‐exclusion experiments have highlighted that top‐down control is pervasive in terrestrial communities, but most of these experiments are simplistic in that they only excluded a single group of predators and the effect of removal was evaluated on a few species from the community. The main goal of our study was to experimentally establish the relative effects of ants and birds on the same arthropod assemblage of canopy trees.

2. We conducted 1‐year long manipulative experiments in an organic citrus grove intended to quantify the independent effects of bird and ant predators on the abundance of arthropods. Birds were excluded with plastic nets whereas ants were excluded with sticky barriers on the trunks. The sticky barrier also excluded other ground dwelling insects, like the European earwig Forficula auricularia L.

3. Both the exclusion of ants and birds affected the arthropod community of the citrus canopies, but the exclusion of ants was far more important than the exclusion of birds. Indeed, almost all groups of arthropods had higher abundance in ant‐excluded than in control trees, whereas only dermapterans were more abundant in bird‐excluded than in control trees. A more detailed analysis conducted on spiders also showed that the effect of ant exclusion was limited to a few families rather than being widespread over the entire diverse spectrum of spiders.

4. Our results suggest that the relative importance of vertebrate and invertebrate predators in regulating arthropod populations largely depends on the nature of the predator–prey system.
Open source in Swedish companies: where are we?
Authors: Lundell Björn , Lings Brian , Lindqvist Edvin
Published: March 2010

Open Source (OS) is a phenomenon of increasing significance for organizations, offering the prospect of effective alternative business solutions and new business opportunities. A number of surveys have been conducted in various countries with the purpose of understanding the state of practice with respect to OS in companies. In this paper we report on a study of the perceptions of OS and the uptake of OS products and development models in Swedish companies. The study used purposeful sampling of companies that have an expressed interest in OS, and the survey was conducted using a set of pre‐prepared questions. Its goal was to investigate the extent to which OS has influenced business thinking, as seen from the standpoint of stakeholders. We found that uptake is much higher than reported in earlier studies, but as with previous studies, activity is still concentrated in small and medium‐sized enterprises (SMEs). There is increased evidence of interest beyond the simple use of OS components at the infrastructure level. Further, a significant proportion of the companies studied are supporting the OS community as well as benefiting from it. Support includes participation in existing projects and the release of new software under OS licenses.
The contraceptive effect of a novel filtering‐type nano‐copper complex/polymer composites intra‐vas device on male animals
Authors: Chen Z.‐L. , Huang X.‐B. , Suo J.‐P. , Li J. , Sun L.
Published: March 2010

Contraceptive techniques which target vas deferens have been paid great attention for their good efficacy, safety and reversibility. We have made a filtering‐type intra‐vas device (IVD) using nano‐copper complex/polymer composites. Twenty male adult Beagle dogs and 40 male rabbits were randomly assigned to four groups (sham‐operation, IVD, reversal and vasectomy groups). Dogs’ semen parameters, concentration of α‐glucosidase, copper and zinc ions were tested pre‐operation and 1, 3, 6 and 12 months post‐operation. The pregnancy rates of the rabbits were evaluated by mating trials after the IVDs were implanted. The histology of testis, epididymides and vas deferens of the animals was examined using an electron microscope. Apoptosis of the cells in the testes, epididymides and vas deferens was detected by TUNEL method. There was no sperm in the semen of dogs, which had been inserted IVD and vasectomized at 1, 3, 6 and 12 months post‐operation. The concentration of α‐glucosidase in the IVD group, reversal group and sham‐operation group was not significantly different between pre‐ and post‐operation. The pregnancy rates of the female rabbits in the vasectomy, IVD and reversal groups were all zero, but the pregnancy rate in the reversal group, after taking out IVD, and that of the sham‐operation group was 60% and 80%, respectively. The ultrastructures of the testes, epididymides and vas deferens of the male animals in the IVD group and sham‐operation group were in normal ranges compared with the vasectomy group. The apoptosis of the cells in the testes, epididymides and vas deferens in the vasectomy group of both dogs and rabbits was obvious compared with the other groups. No significant changes in the quantities of copper and zinc ions were found in semen of the male dogs both pre‐ and post‐operation. Our studies demonstrated that the filtering‐type nano‐copper complex/polymer composites intra‐vas device may be an efficacious, safe and reversible male contraceptive device.
Strong relationships between vegetation and two perpendicular climate gradients high on a tropical mountain in Hawai‘i
Authors: Crausbay Shelley D. , Hotchkiss Sara C.
Published: March 2010

Aim  We compared vegetation patterns at high elevation on a tropical mountain with edaphic properties and position along climate gradients to examine this landscape’s potential sensitivity to climate change.

Location  Our study covers the cloud forest, the ecotone at the cloud forest’s upper limit, and the alpine grassland, on the north‐east corner of windward Haleakalā, Hawai‘i. The study area brackets the mean trade wind inversion (TWI), encompasses a perpendicular, east–west precipitation gradient and includes multiple edaphic contexts.

Methods  We collected vegetation structure and composition data in 134 plots from 1900 to 2400 m elevation, stratified east to west. We used classification trees to compare species assemblage groups with spatial (elevation, easting, aspect) and edaphic (substrate age, texture, degree slope) variables derived from a 10‐m digital elevation model and a digital geological map.

Results  The forest line was physiognomically sharp, and a Shipley–Keddy test showed that species distributional limits were aggregated there. Forest line elevation was not consistent, but dropped nearly 200 m from east to west. Indicator taxa for positions above or below the forest line varied from east to west. Hierarchical clustering identified species assemblage groups with significantly different composition that were distributed across the TWI and/or along east–west climate gradients. Classification trees showed that edaphic properties were not well associated with species assemblage groups, but position along two perpendicular climate gradients was. Compositional turnover was detected along both elevational and east–west gradients. Turnover of the cloud forest’s epiphytic community was particularly pronounced across east–west gradients. Lichen abundance was significantly higher at the drier end of the east–west moisture gradient, and bryophyte abundance was higher at the wetter end.

Main conclusions  Modern spatial patterns suggest that this landscape will respond to changes in moisture balance through changes in species assemblage and structure, especially at the ecotone. Furthermore, ecotone response to climate change may vary from east to west because of differences in species‐specific constraints or climatic context.
Effects of Hypoglycaemia on Neurotransmitter and Hormone Receptor Gene Expression in Laser‐Dissected Arcuate Neuropeptide Y/Agouti‐Related Peptide Neurones
Authors: Briski K. P. , Nedungadi T. P. , Koshy Cherian A.
Published: March 2010

Arcuate neuropeptide Y (NPY)/agouti‐related pepide (AgRP) neurones regulate energy homeostasis, and express the putative glucosensor, glucokinase (GCK). The present study performed multi‐transcriptional profiling of these neurones to characterise NPY, AgRP and GCK gene expression during intermediate insulin‐induced hypoglycaemia, and to determine whether these transcriptional responses acclimate to repeated insulin dosing. We also examined whether these neurones express insulin, glucocorticoid and oestrogen receptor gene transcripts, and whether the levels of these receptor mRNAs are modified by insulin‐induced hypoglycaemia. Individual NPY‐immunoreactive neurones were laser‐microdissected from the caudal arcuate nucleus after single or serial dosing with neutral protamine Hagedorn insulin (NPH), and evaluated by quantitative real‐time reverse transcriptase‐polymerase chain reaction for the assessment of neurotransmitter and receptor gene expression. Mean NPY and AgRP mRNA in harvested NPY neurones was unchanged or augmented, respectively, by one NPH dose, although repeated NPH administration up‐regulated NPY, whereas AgRP gene transcripts were down‐regulated. NPH elicited divergent modifications in the ERα and ERβ mRNA content of sampled neurones. ERα transcripts were amplified by both acute and chronic NPH‐induced hypoglycaemia, whereas ERβ gene expression was unaltered during a single bout, but suppressed during recurring hypoglycaemia. Glucocorticoid receptor (GR) mRNA levels were increased by a single insulin dose, but unaffected by serial NPH dosing. Insulin receptor‐β chain (InsRb) gene transcripts were insensitive to acute NPH‐induced hypoglycaemia, but repeated NPH inhibited this gene transcript. Neither acute nor recurring hypoglycaemia modified GCK mRNA levels in caudal hypothalamic arcuate nucleus (ARH) NPY/AgRP neurones, but baseline GCK transcription was suppressed by the latter. This evidence for the habituation of hypoglycaemic patterns of InsRb, GR and ERβ gene transcription to serial NPH dosing implies that such treatment may alter reactivity of caudal ARH NPY/AgRP neurones to receptor ligands, and supports the need to determine whether adaptive changes in neuronal sensitivity to insulin, corticosterone and/or oestrogen cause up‐ versus down‐regulation of NPY and AgRP neurotransmission, respectively, by this caudal ARH subpopulation during chronic hypoglycaemia.