bluuebunny/crossref_metadata_2025 huggingface dataset:
Influences of nonsolvent and temperature on critical viscoelastic behaviors of ternary polyacrylonitrile solutions around the sol‐gel threshold
Authors: Ma Caixia , Du Weiping , Chen Huifang , Liu Zhanlian , Qin Zongyi , Pan Ding
Published: October 2008

Viscoelastic experiments were performed to study the influence of nonsolvent and temperature on critical viscoelastic behaviors of ternary polyacrylonitrile (PAN) solutions around the sol‐gel threshold. The dynamic critical parameters around the sol‐gel threshold were determined using dynamic rheometer. The sol‐gel transition takes place at a critical gel temperature at which the scaling law of G′(ω) ∼ G″(ω) ∝ ωn holds, allowing an accurate determination of the critical gel temperature by means of the frequency independence of the loss tangent. Although the gel points of PAN solutions increase with increasing H2O content, the results show that the scaling exponent n at the gel point is found to be universal for all ternary PAN solutions, which is independent of temperature and H2O content, indicating the similarity of the fractal structure in the critical PAN gels. The gelation of ternary PAN solutions induced by adding a nonsolvent and by decreasing the temperature is demonstrated to be a thermoreversible process, which implies that the PAN gels are physical gels. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2637–2643, 2008
All‐organic actuator fabricated with single wall carbon nanotube electrodes
Authors: Kang Jin Ho , Park Cheol , Lowther Sharon E. , Harrison Joycelyn S. , Park Chan Eon
Published: October 2008

Compliant electrodes to replace conventional metal electrodes have been required for many actuators to relieve the constraint on the electroactive layer. Many conducting polymers have been proposed for the alternative electrodes, but they still have a problem of poor thermal stability. This article reports a novel all‐ organic actuator with single wall carbon nanotube (SWCNT) films as an alternative electrode. The SWCNT film was obtained by filtering a SWCNT solution through an anodized alumina membrane. The conductivity of the SWCNT film was about 280 S/cm. The performance of the SWCNT film electrode was characterized by measuring the dielectric properties of NASA Langley Research Center – Electroactive Polymer (LaRC‐EAP) sandwiched by the SWCNT electrodes over a broad range of temperature (from 25 to 280 °C) and frequency (from 1 kHz to 1 MHz). The all‐organic actuator with the SWCNT electrodes showed a larger electric field‐induced strain than that with metal electrodes, under identical measurement conditions. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 2532–2538, 2008
Tuberculosis: guide to diagnosis, treatment and prevention
Authors: Raza Mansoor , Heyderman Robert
Published: October 2008

Tuberculosis remains a major problem worldwide, with increasing numbers of cases in the UK in adults born abroad. Here, the authors describe the current recommendations for diagnosis, treatment and prevention. Copyright © 2008 Wiley Interface Ltd
Antioxidant and free‐radical scavenging activities of Allium roseum and Allium subhirsutum
Authors: Štajner D. , Popovic B. M. , Čanadanović‐Brunet J. , Igić R. S.
Published: October 2008

This study was designed to examine the antioxidant and free‐radical scavenging activities of two Allium species, Allium roseum and Allium subhirsutum. This study reports the results concerning bulb, stalk and leaf antioxidant enzyme activities (superoxide dismutase, catalase, guaiacol peroxidase and glutathione peroxidase), quantities of malonyldialdehyde, •OH and O2•− radicals and total antioxidant capacity determined by the FRAP method. Scavenging activities were determined by ESR method. The total antioxidant capacity was the highest in the leaves of Allium roseum. Among the investigated organs the leaves exhibited the highest antioxidant activities in all investigated Allium species. The highest ESR (84.61%) scavenger activity was observed in the leaves of Allium roseum. Copyright © 2008 John Wiley & Sons, Ltd.
Extreme loads for an offshore wind turbine using statistical extrapolation from limited field data
Authors: Agarwal Puneet , Manuel Lance
Published: October 2008

When interest is in establishing extreme loads for wind turbines, it is common to either carry out extensive simulation studies or undertake a field measurement campaign. At the Blyth offshore wind farm in the UK, a 2 MW wind turbine was instrumented, and environment and load data were obtained in a previous study. Here, we discuss how such data, even though very limited, may be used along with parametric models to establish extreme loads associated with return periods on the order of 20–50 years. The environmental characteristics at the Blyth site are such that wind and waves are of primary importance. Distributions for the extreme mudline bending moment are established using parametric models. Long‐term loads are derived for different wind regimes possible at the site and the results are compared. Using bootstrap techniques, the effect of variability in the parameters for load distribution is investigated. Copyright © 2008 John Wiley & Sons, Ltd.
Strukturelle Genomvarianten
Authors: Ullmann R.
Published: October 2008

Unter strukturellen Genomvarianten (SV) versteht man chromosomale Veränderungen größer als 1 kb. Obwohl es dank des technischen Fortschritts immer besser gelingt, die qualitativen und quantitativen Eigenschaften von SV zu definieren, sind deren phänotypischen Konsequenzen meist nur unzureichend verstanden. Die Unterscheidung zwischen neutraler Variante, prädisponierendem Faktor und krankheitsverursachender Veränderung stellt heute eine der großen Herausforderungen in der humangenetischen Diagnostik dar.
Transobturator tape procedure versus tension‐free vaginal tape for treatment of stress urinary incontinence
Authors: Wang Wenyan , Zhu Lan , Lang Jinghe
Published: October 2008

Objective

To compare the efficacy and safety of the tension‐free vaginal tape (TVT) and inside‐out transobturator tape (TVT‐O) procedures for the treatment of stress urinary incontinence (SUI).

Methods

A total of 315 women with or without concomitant pelvic organ prolapse repairs were randomly allocated to undergo a TVT or TVT‐O procedure. Demographic data, intra‐ and postoperative complications, and surgical outcomes were analyzed.

Results

Fifteen patients were lost to follow‐up. There were no significant differences in cure rates between the 2 groups at 6, 12, 24, and 36 months' follow‐up. Hematomas occurred in 4 patients and there were 6 vaginal tape erosions. Urinary retention and de novo urinary urgency were similar in both groups. The operative time was significantly shorter for TVT‐O than for TVT without other procedures (P < 0.001) and postoperative groin/thigh pain was higher (P < 0.05) in the TVT‐O group.

Conclusion

Both techniques appear equally effective for the treatment of SUI. However, TVT‐O had a shorter operative time and a higher rate of groin/thigh pain.
Fuzzy Logic for Elimination of Redundant Information of Microarray Data
Authors: Huerta Edmundo Bonilla , Duval Béatrice , Hao Jin-Kao
Published: October 2008

Gene subset selection is essential for classification and analysis of microarray data. However, gene selection is known to be a very difficult task since gene expression data not only have high dimensionalities, but also contain redundant information and noises. To cope with these difficulties, this paper introduces a fuzzy logic based pre-processing approach composed of two main steps. First, we use fuzzy inference rules to transform the gene expression levels of a given dataset into fuzzy values. Then we apply a similarity relation to these fuzzy values to define fuzzy equivalence groups, each group containing strongly similar genes. Dimension reduction is achieved by considering for each group of similar genes a single representative based on mutual information. To assess the usefulness of this approach, extensive experimentations were carried out on three well-known public datasets with a combined classification model using three statistic filters and three classifiers.
Identification of MicroRNA Precursors with Support Vector Machine and String Kernel
Authors: Xu Jian-Hua , Li Fei , Sun Qiu-Feng
Published: October 2008

MicroRNAs (miRNAs) are one family of short (21–23 nt) regulatory non-coding RNAs processed from long (70–110 nt) miRNA precursors (pre-miRNAs). Identifying true and false precursors plays an important role in computational identification of miRNAs. Some numerical features have been extracted from precursor sequences and their secondary structures to suit some classification methods; however, they may lose some usefully discriminative information hidden in sequences and structures. In this study, pre-miRNA sequences and their secondary structures are directly used to construct an exponential kernel based on weighted Levenshtein distance between two sequences. This string kernel is then combined with support vector machine (SVM) for detecting true and false pre-miRNAs. Based on 331 training samples of true and false human pre-miRNAs, 2 key parameters in SVM are selected by 5-fold cross validation and grid search, and 5 realizations with different 5-fold partitions are executed. Among 16 independent test sets from 3 human, 8 animal, 2 plant, 1 virus, and 2 artificially false human pre-miRNAs, our method statistically outperforms the previous SVM-based technique on 11 sets, including 3 human, 7 animal, and 1 false human pre-miRNAs. In particular, pre-miRNAs with multiple loops that were usually excluded in the previous work are correctly identified in this study with an accuracy of 92.66%.
30 years of pain treatment in Italy: past, present and future
Authors: Allegri M. , Tinelli C. , Sandrini G. , Bonezzi C.
Published: October 2008

Chronic pain is a situation that bring patients to ask for a medical intervention and can be originated from many different pathologic conditions. Nowadays, recent advancements in pain treatment have made possible to control pain in many patients, allowing them to return to daily activities. Anaesthesiologists are the modern pain specialists, and must know and define the origin of pain in every case: the comprehension of pain mechanisms gives them the possibility for a planned strategy of treatment.

In this work we perform a overview about the “state of the art” of pain treatment in Italy analyzing what are the problems that require to focalize our attention.

Therefore, sometimes many visits are necessary for a correct diagnosis and successful therapy. Pain management is still a young speciality, and the Italian pain specialist is often a self made expert who needs proper structures and dedicated people: the result is a different treatment not only between the hospitals but also in the same pain conditions.

Although it seems that many of the new techniques used to control pain are successful, few studies and controlled trials have been done to verify long‐term efficacy and potential adverse effects.
Regional anaesthesia and side effects: Is it safe?
Authors: Allegri Massimo , Grossi Paolo , Ferrari Federica , Borghi Battista
Published: October 2008

The availability of new local anaesthetics and the improvement of regional techniques has caused a great increase of central and peripheral blockades for anaesthesia as well as for postoperative pain. The increase of these blockades tends to increase the rate of complications.

In a Pubmed research we found more than 400 articles about this topic. In the analysis of the literature we divided two major chapters: severe complications after central blockades and after peripheral nerve blocks.

Analysis of the literature showed a lower incidence of serious complications associated with neuroaxial anaesthesia. It is important to underline that authors stressed the importance of predisposing factors like pre‐existing peripheral or central neurological disease, arteriosclerotic disease, osteoporosis and spinal stenosis, diabetes, cancer, chronic alcohol abuse and steroid therapy. Otherwise, the most concern about peripheral nerve blocks is nerve injury and/or neuropathy due to potential toxicity of local anaesthetics or due a nerve lesion for needle trauma or infection.

Even if the incidence of severe side effects is rare, it is very important that we approach this technique knowing well the risks (even if low) so that we can prevent them improving the outcome of patients. Nevertheless, there is again the need to have a large prospective study to investigate the real incidence of severe complications of central and peripheral blocks.
Regional anesthesia and pain management: What's new
Authors: Urmey William F.
Published: October 2008

Present technological advances allow more accurate needle/catheter placement. Continuous regional analgesia with perineural catheters has been shown to significantly improve outcome. Grossi introduced the “anesthetic line” concept as a guide for approaches to perineural regional anesthesia. Winnie introduced the concept of the brachial plexus sheath that envelops the neural or neurovascular plexus. He discussed similar sheathes applying to the lower extremity. Recent studies support his sheath theory. Anatomical as well as local anesthetic distribution studies support a new concept that has relevant clinical applications. This concept is the presence of an anatomical impingement point at the junction of the clavicle and first rib that acts as a functional point of resistance to the flow of an injectate beyond this point. Similarly, it restricts the advancement of a catheter. The brachial plexus should be thought of as an hourglass‐shaped anatomical compartment with the narrow portion of the hourglass at the costoclavicular junction. Above the clavicle the compartment is triangular and flat. Below the clavicle a larger cylindrical half‐hourglass shape prevails. Injections above and or below the clavicle lead to different anesthetic distributions as well as clinical results. This anatomy will continue to be elucidated and must be kept in mind when targeting anesthesia or analgesia by single or multiple injections and for optimal placement of catheter or catheters for continuous infusions.
Ultrasound in acute and chronic pain: Why is it necessary?
Authors: Fanelli Guido , Baciarello Marco
Published: October 2008

High success rates are attainable using state‐of‐the‐art multiple electrical nerve stimulation, loss‐of‐resistance or fluoroscopic guidance techniques in most interventional acute and chronic pain techniques. Nevertheless, ultrasound (US) guidance for regional anesthesia and pain medicine offers compelling advantages in terms of precise location of anatomical structures, controlled needle advancement and local anesthetic deposition. Accurate models are needed to define criteria for the reproducibility of US examination and nerve block. Familiarization with US imaging is quickly becoming necessary as the next step in the evolution of interventional techniques for treating pain; consistent training by competent professionals is necessary to effectively leverage on the advantages of this technology.
Ultrasounds for regional anesthesia
Authors: Albani Alessandro
Published: October 2008

Regional anesthesia is living a new era due to the introduction of ultrasounds for regional blocks: several anesthesia procedures with inherent risks of complications have greatly improved in the last years thanks to techniques concerning the “visibility” of the procedures. Ultrasound guided blocks are an important advance in quality, effectiveness and, perhaps, safety when performing peripheral blocks. Some of the blocks considered quite difficult to perform with the electroneurostimulator only are in fact made easier by the ultrasounds technique (see for example the interscalene block or the sopraclavicular block). Having a progressive and careful learning curve is mandatory as reports of complications are rising in the literature.
Ultrasound in paediatric anaesthesia
Authors: Mossetti Valeria , Ivani Giorgio
Published: October 2008

Regional anaesthesia is widely employed for the perioperative pain control also in children. The literature data confirm the very low rate of complications and side effects of regional anaesthesia in children but there are key points for performing a block and placing a catheter in children: there is the need of good knowledge of anatomical and physiological differences; the use of the more recent local anaesthetics increases the therapeutic window and it is mandatory to work with dedicated paediatric tools.

Through the use of new techniques like ultrasound we can improve the success of the blocks reducing the risks and adding safety and efficacy to a technique that is part of our daily clinical practice.
Ultrasound in interventional pain management
Authors: Curatolo Michele , Eichenberger Urs
Published: October 2008

Ultrasound (US) is an increasingly used imaging technique in interventional pain management. It allows the identification of soft tissues, vessels and nerves, without exposing patients and personnel to radiation. Imaging can be performed continuously and the fluid injected is visualized in a real time fashion. Possible applications are nerve blocks of the cervical and lumbar zygapophysial joints, stellate ganglion block, intercostal nerve blocks, blocks of painful stump neuromas, caudal epidural injections and injections of trigger/tender points. Due to direct nerve visualization, US has a potential application for destructive procedures, such as cryoanalgesia, radiofrequency lesions or chemical neurolysis. Limitations are the poor resolution of narrow‐gauge needles, the lost of resolution with increasing working depth and possible interference of echoes from overlying structures with the image of the target area. US opens new perspectives in interventional pain management. However, there is a need for clinical trials investigating efficacy and safety of US‐guided pain procedures. Until these studies are made, US can not replace fluoroscopy or computed tomography in routine clinical practice and remainS domain of well‐trained and experienced physicians. The limited evidence supporting the clinical utility of nerve blocks remains a problem, irrespective of the imaging technique employed.
State of the art of the free-living marine Monhysteridae (Nematoda)
Authors: Fonseca Gustavo , Decraemer Wilfrida
Published: October 2008

The family Monhysteridae is characterized by 17 valid genera, seven of which are known to be free-living, inhabiting marine sediments. In total, 70 valid marine species are ascribed to these seven genera. Overall, the family is characterized by a confused taxonomic history with a large list of synonyms and species inquirendae. The taxonomic problem is not restricted to the old literature, but inconsistencies also appeared in recent studies. The aim of this study is to show the most important diagnostic characters to identify each genus and provide taxonomic tools for species identification. Dichotomous-keys and illustration-guides are attempted for the marine monhysterid species. For the family and each subfamily, tribe and marine genus a brief historical background, diagnosis and a list of valid species is provided. Hereby, we propose to transfer eight species of the genus Thalassomonhystera to the genus Monhystrella.
SYMMETRY RESULT FOR SOME OVERDETERMINED VALUE PROBLEMS
Authors: BARKATOU MOHAMMED , KHATMI SAMIRA
Published: October 2008

The aim of this article is to prove a symmetry result for several overdetermined boundary value problems. For the two first problems, our method combines the maximum principle with the monotonicity of the mean curvature. For the others, we use essentially the compatibility condition of the Neumann problem.
SUCCESSIVE ITERATION AND POSITIVE SOLUTIONS FOR Ap-LAPLACIAN MULTIPOINT BOUNDARY VALUE PROBLEM
Authors: SUN BO , ZHAO XIANGKUI , GE WEIGAO
Published: October 2008

In this paper, we study the existence of positive solutions for the one-dimensionalp-Laplacian differential equation,subject to the multipoint boundary conditionby applying a monotone iterative method.
Constitutions and Democratic Performance in Semi-Presidential Democracies
Authors: CHEIBUB JOSÉ ANTONIO , CHERNYKH SVITLANA
Published: October 2008

In 1946 there were three democracies in the world with constitutions that, on the one hand, required the government to obtain the support of a legislative majority in order to come to and remain in power and, on the other hand, established a popularly elected president. In 2002, this number had grown to 25. Constitutions with this feature are often considered to be problematic, and, given the number of new democracies that have adopted them, have received considerable attention from political scientists. The primary concern has to do with the potential for conflict between the assembly supported government and the popularly elected president, which may lead to unstable governments, policy paralysis, and the eventual undermining of the democratic regime. Concern has also been raised regarding the negative role a popularly elected president may have on party development and the ‘chain of delegation’ that in a pure parliamentary democracy runs from voters to government through political parties. In this paper, we examine the effect the combination of assembly confidence with a popularly elected president has on government instability, accountability, legislative effectiveness, and democratic survival. We also examine the impact on these outcomes of different combinations of presidential powers. We find that the introduction of a popularly elected president in parliamentary constitutions is of little significant impact and that the preoccupation with the specific powers of the president is mostly overblown.
Statistics of fluctuating colloidal fluid-fluid interfaces
Authors: de Villeneuve V. W. A. , van Leeuwen J. M. J. , van Saarloos W. , Lekkerkerker H. N. W.
Published: October 2008

Fluctuations of the interface between coexisting colloidal fluid phases have been measured with confocal microscopy. Due to a very low surface tension, the thermal motions of the interface are so slow that a record can be made of the positions of the interface. The theory of the interfacial height fluctuations is developed. For a host of correlation functions, the experimental data are compared with the theoretical expressions. The agreement between theory and experiment is remarkably good.
Development of a fast position-sensitive laser beam detector
Authors: Chavez Isaac , Huang Rongxin , Henderson Kevin , Florin Ernst-Ludwig , Raizen Mark G.
Published: October 2008

We report the development of a fast position-sensitive laser beam detector. The detector uses a fiber-optic bundle that spatially splits the incident beam, followed by a fast balanced photodetector. The detector is applied to the study of Brownian motion of particles on fast time scales with 1 Å spatial resolution. Future applications include the study of molecule motors, protein folding, as well as cellular processes.
On computing the trace of the kernel of the homogeneous Fredholm’s equation
Authors: Velázquez-Arcos J. M. , Vargas C. A. , Fernández-Chapou J. L. , Salas-Brito A. L.
Published: October 2008

A method for computing the trace of the kernel of the homogeneous Fredholm’s equation for resonant states arising from nonlocal potentials is proposed. We show that this integral formulation is convergent.
Color control of white photoluminescence from carbon-incorporated silicon oxide
Authors: Ishikawa Yukari , Vasin A. V. , Salonen J. , Muto S. , Lysenko V. S. , Nazarov A. N. , Shibata N. , Lehto V.-P.
Published: October 2008

Color control of the white photoluminescence (PL) from carbon-incorporated silicon oxide is demonstrated. The carbon-incorporated silicon oxide was fabricated by carbonization of porous silicon in acetylene flow (at 650 and 850 °C) followed by wet oxidation (at 650 and 800 °C). It was shown that PL color can be controlled in the range of blue-white and yellow-white by selecting the porosity of starting porous silicon as well as the carbonization and oxidation temperatures. Low-temperature oxidation resulted in bluish light emission in lower porosity series, while high-temperature oxidation promoted yellow-white light emission. The maximal integral intensity of PL was observed after oxidation at 800 °C. It was shown that white PL from carbon-incorporated silicon oxide has blue and yellow-white PL bands originating from different light-emitting centers. The origin of blue PL is attributed to defects in silicon dioxide. Some trap levels at the interface of the carbon clusters and silicon oxide are suggested to be the origin of the yellow-white light emission.
Magneto-optics of single Rashba spintronic quantum dots subjected to a perpendicular magnetic field: Fundamentals
Authors: Kushwaha Manvir S.
Published: October 2008

We report on the theoretical investigation of the effect of the Rashba-type spin-orbit interaction (SOI) on the Fock–Darwin energy spectrum in the parabolically confined quantum dots in the presence of a perpendicular (to the original two-dimensional electron gas) magnetic field. The study is based on the formal (analytical) results without resorting to any numerical simulation. We observe that the SOI modifies drastically the optical, thermodynamic, as well as magneto-optical properties of the (narrow-gap InAs) quantum dots. We discuss the dependence of the Fock–Darwin spectrum, Fermi energy, optical transitions, and magnetization on all the important parameters involved in the theory such as, for example, the orbital quantum number, the magnetic field, the confinement potential, and the Rashba parameter that characterizes the strength of the SOI. The illustrative examples include the results both with and without the SOI, for the sake of comparison. One of the most important observations is that the Rashba SOI causes the band mixing and band shifting in the quantum dots and the Fock–Darwin energy spectrum becomes richer but complex. This complexity seems to arise due to an intricate interplay between the SOI and the Zeeman energy.
Gyrokinetic turbulence simulations at high plasma beta
Authors: Pueschel M. J. , Kammerer M. , Jenko F.
Published: October 2008

Electromagnetic gyrokinetic turbulence simulations employing Cyclone Base Case parameters are presented for β values up to and beyond the kinetic ballooning threshold. The β scaling of the turbulent transport is found to be linked to a complex interplay of linear and nonlinear effects. Linear investigation of the kinetic ballooning mode is performed in detail, while nonlinearly, it is found to dominate the turbulence only in a fairly narrow range of β values just below the respective ideal limit. The magnetic transport scales like β2 and is well described by a Rechester–Rosenbluth-type ansatz.
Inertial migration of spherical particles in circular Poiseuille flow at moderately high Reynolds numbers
Authors: Shao Xueming , Yu Zhaosheng , Sun Bo
Published: October 2008

The inertial migration of spherical particles in a circular Poiseuille flow is numerically investigated for the tube Reynolds number up to 2200. The periodic boundary condition is imposed in the streamwise direction. The equilibrium positions, the migration velocity, and the angular velocity of a single particle in a tube cell are examined at different Reynolds numbers, particle-tube size ratios, and tube lengths. Inner equilibrium positions are observed as the Reynolds number exceeds a critical value, in qualitatively agreement with the previous experimental observations [J.-P. Matas, J. F. Morris, and E. Guazzelli, J. Fluid Mech. 515, 171 (2004)]. Our results indicate that the hydrodynamic interactions between the particles in different periodic cells have significant effects on the migration of the particles at the tube length being even as large as 6.7 particle diameters and they tend to stabilize the particles at the outer Segré–Silberberg equilibrium positions and to suppress the emergence of the inner equilibrium positions. A mirror-symmetric traveling-wave-like structure is observed when the particle Reynolds number is large enough. A pair of counter-rotating streamwise vortices exists at both upstream and downstream of the particle but with different rotating directions. The fluids in the half of the pipe without the particle flow more slowly and most fluids in the other half with the particle move faster with respect to the parabolic profile. The intensity of the structure is influenced by the local particle Reynolds number, the particle motion, and the tube length. In addition, the migration of multiple particles in a periodic tube cell is examined. We attribute the disparity in the critical particle Reynolds number for the occurrence of the inner particle annulus for the experiments and our simulations to the effect of the tube length or the periodic boundary condition in our numerical model.
Magnetic tuning of electrically resonant metamaterial with inclusion of ferrite
Authors: Kang Lei , Zhao Qian , Zhao Hongjie , Zhou Ji
Published: October 2008

We experimentally demonstrate a magnetic tuning of electrically resonant metamaterial (EMM) at microwave frequencies by introducing microwave ferrite rods into the periodic array of electrically resonant element. Different from those based on controlling the capacitance of equivalent LC circuit, this tunability arises from a mechanism of magnetically tuning the inductance of resonant element via the active ambient effective permeability. For magnetic fields from 0 to 5000 Oe, resonance frequency of the EMM can be continuously and reversibly tuned in a range of about 800 MHz. The active effective permittivity has also been investigated through the simulated scattering parameters.
Near-isotropic performance of intrinsically anisotropic high-temperature superconducting tapes due to self-assembled nanostructures
Authors: Zuev Y. L. , Christen D. K. , Wee S. H. , Goyal A. , Cook S. W.
Published: October 2008

We report material and operating parameter conditions where prototype high-temperature superconducting tape conductors exhibit in-plane critical current characteristics that are essentially field orientation independent. This phenomenon is observed for specific magnetic field intensities that depend on the operating temperature and in materials having strong flux pinning by extended nanoscale structures aligned roughly along the crystalline c-axis. The effect can be described by a simple model for the field dependence of critical current density, generalized for anisotropic electronic response. This description may provide insight into means to fine tune the material properties for nearly isotropic performance characteristics at a preferred field and temperature.
Thermal stability of amorphous silicon/silicon nitride stacks for passivating crystalline silicon solar cells
Authors: Gatz S. , Plagwitz H. , Altermatt P. P. , Terheiden B. , Brendel R.
Published: October 2008

The thermal stability of amorphous silicon/silicon nitride double layer surface passivation of p-type and n+-type crystalline surfaces is investigated for different deposition temperatures of the silicon nitride capping layer. An increase from 300to400°C results in a significant improvement of the thermal stability of the surface passivation. The minimum surface recombination velocity achieved on p-type (1.5Ωcm) silicon wafers is 0.75±0.6cm∕s and remains at 10±0.5cm∕s after 30min annealing at 500°C.
Regulation of neuronal connexin-36 channels by pH
Authors: González-Nieto Daniel , Gómez-Hernández Juan M. , Larrosa Belén , Gutiérrez Cristina , Muñoz María D. , Fasciani Ilaria , O'Brien John , Zappalà Agata , Cicirata Federico , Barrio Luis C.
Published: October 2008

Neurotransmission through electrical synapses plays an important role in the spike synchrony among neurons and oscillation of neuronal networks. Indeed, electrical transmission has been implicated in the hypersynchronous electrical activity of epilepsy. We have investigated the influence of intracellular pH on the strength of electrical coupling mediated by connexin36 (Cx36), the principal gap junction protein in the electrical synapses of vertebrates. In striking contrast to other connexin isoforms, the activity of Cx36 channels decreases following alkalosis rather than acidosis when it is expressed in
Xenopus
oocytes and N2A cells. This uncoupling of Cx36 channels upon alkalinization occurred in the vertebrate orthologues analyzed (human, mouse, chicken, perch, and skate). While intracellular acidification caused a mild or moderate increase in the junctional conductance of virtually all these channels, the coupling of the skate Cx35 channel was partially blocked by acidosis. The mutational analysis suggests that the Cx36 channels may contain two gating mechanisms operating with opposing sensitivity to pH. One gate, the dominant mechanism, closes for alkalosis and it probably involves an interaction between the C- and N-terminal domains, while a secondary acid sensing gate only causes minor, albeit saturating, changes in coupling following acidosis and alkalosis. Thus, we conclude that neuronal Cx36 channels undergo unique regulation by pH
i
since their activity is inhibited by alkalosis rather than acidosis. These data provide a novel basis to define the relevance and consequences of the pH-dependent modulation of Cx36 synapses under physiological and pathological conditions.
The photorespiratory glycolate metabolism is essential for cyanobacteria and might have been conveyed endosymbiontically to plants
Authors: Eisenhut Marion , Ruth Wolfgang , Haimovich Maya , Bauwe Hermann , Kaplan Aaron , Hagemann Martin
Published: October 2008

Photorespiratory 2-phosphoglycolate (2PG) metabolism is essential for photosynthesis in higher plants but thought to be superfluous in cyanobacteria because of their ability to concentrate CO
2
internally and thereby inhibit photorespiration. Here, we show that 3 routes for 2PG metabolism are present in the model cyanobacterium
Synechocystis
sp. strain PCC 6803. In addition to the photorespiratory C2 cycle characterized in plants, this cyanobacterium also possesses the bacterial glycerate pathway and is able to completely decarboxylate glyoxylate via oxalate. A triple mutant with defects in all 3 routes of 2PG metabolism exhibited a high-CO
2
-requiring (HCR) phenotype. All these catabolic routes start with glyoxylate, which can be synthesized by 2 different forms of glycolate dehydrogenase (GlcD). Mutants defective in one or both GlcD proteins accumulated glycolate under high CO
2
level and the double mutant Δ
glcD1
/Δ
glcD2
was unable to grow under low CO
2
. The HCR phenotype of both the double and the triple mutant could not be attributed to a significantly reduced affinity to CO
2
, such as in other cyanobacterial HCR mutants defective in the CO
2
-concentrating mechanism (CCM). These unexpected findings of an HCR phenotype in the presence of an active CCM indicate that 2PG metabolism is essential for the viability of all organisms that perform oxygenic photosynthesis, including cyanobacteria and C3 plants, at ambient CO
2
conditions. These data and phylogenetic analyses suggest cyanobacteria as the evolutionary origin not only of oxygenic photosynthesis but also of an ancient photorespiratory 2PG metabolism.
Fluorescence resonance energy transfer imaging of PKC signalling in living cells using genetically encoded fluorescent probes
Authors: Goedhart Joachim , Gadella Theodorus W.J
Published: October 2008

Perception of ligands in the extracellular space by transmembrane receptors initiates signal transduction. The conformation change of the receptor induces changes of intracellular signalling components, including altered cellular concentration, altered subcellular location, altered conformation and altered interacting partners. Biochemical approaches have yielded a lot of information about these processes. However, methods that are compatible with analysis of single living cells are often preferred, since cells are highly organized and their response is usually spatially heterogeneous. In addition, the study of signalling cascades requires high temporal resolution. Fluorescence imaging approaches meet these requirements. Moreover, imaging approaches can be combined with genetically encoded green fluorescent protein-based probes that have a high selectivity and sensitivity for the process/molecule of interest. Nowadays, many genetically encoded probes are available for visualizing signalling in living cells. This review is centred on a key regulator of cellular signalling, protein kinase C (PKC). We will discuss imaging approaches that are used for analysing the molecules involved in activation of PKC, visualizing the dynamics of the location of PKC, measuring the conformation of PKC and quantifying the activity of PKC. These approaches are of general interest since they can be applied to study the dynamics, conformation and activity of any protein in living cells.
Spatio-temporal waves and targeted vaccination in recurrent epidemic network models
Authors: Litvak-Hinenzon Anna , Stone Lewi
Published: October 2008

The success of an infectious disease to invade a population is strongly controlled by the population's specific connectivity structure. Here, a network model is presented as an aid in understanding the role of social behaviour and heterogeneous connectivity in determining the spatio-temporal patterns of disease dynamics. We explore the controversial origins of long-term recurrent oscillations believed to be characteristic of diseases that have a period of temporary immunity after infection. In particular, we focus on sexually transmitted diseases such as syphilis, where this controversy is currently under review. Although temporary immunity plays a key role, it is found that, in realistic small-world networks, the social and sexual behaviour of individuals also has a great influence in generating long-term cycles. The model generates circular waves of infection with unusual spatial dynamics that depend on focal areas that act as pacemakers in the population. Eradication of the disease can be efficiently achieved by eliminating the pacemakers with a targeted vaccination scheme. A simple difference equation model is derived, which captures the infection dynamics of the network model and gives insights into their origins and their eradication through vaccination. Illustrative videos may be found in the electronic supplementary material.
Steady electro-osmotic flow of a micropolar fluid in a microchannel
Authors: Siddiqui Abuzar A , Lakhtakia Akhlesh
Published: October 2008

We have formulated and solved the boundary-value problem of steady, symmetric and one-dimensional electro-osmotic flow of a micropolar fluid in a uniform rectangular microchannel, under the action of a uniform applied electric field. The Helmholtz–Smoluchowski equation and velocity for micropolar fluids have also been formulated. Numerical solutions turn out to be virtually identical to the analytic solutions obtained after using the Debye–Hückel approximation, when the microchannel height exceeds the Debye length, provided that the zeta potential is sufficiently small in magnitude. For a fixed Debye length, the mid-channel fluid speed is linearly proportional to the microchannel height when the fluid is micropolar, but not when the fluid is simple Newtonian. The stress and the microrotation are dominant at and in the vicinity of the microchannel walls, regardless of the microchannel height. The mid-channel couple stress decreases, but the couple stress at the walls intensifies, as the microchannel height increases and the flow tends towards turbulence.
Sprint and endurance power and ageing: an analysis of master athletic world records
Authors: Rittweger Jörn , di Prampero Pietro Enrico , Maffulli Nicola , Narici Marco V
Published: October 2008

Human physical performance is notably reduced with ageing. Although the effects of ageing are often compounded by disuse, the study of master athletes provides an opportunity for investigating the effects of ageing
per se
. It is often held that sprinting is more affected than endurance performance. However, past analyses of master athletic world record data have yielded opposite observations. We argue here that our understanding of these data improves by considering how, biomechanically, metabolic power is related to athletic performance. In line with earlier studies, our analysis showed that running speed declines with age in a more pronounced way for endurance events than for sprinting events, confirming former studies. However, when assessing the metabolic power required to achieve the running world records, sprint and endurance events show a relatively uniform decline with age across the different events. This study has reconciled formerly conflicting scientific results and improves our understanding of the ageing process. However, it is unclear as to which are the governing mechanisms that cause the different systems in our body, responsible for sprinting and for endurance performance, to be affected by ageing in a remarkably uniform way.
ATP hydrolysis-driven gating in cystic fibrosis transmembrane conductance regulator
Authors: Muallem Daniella , Vergani Paola
Published: October 2008

Proteins belonging to the ATP-binding cassette superfamily couple ATP binding and hydrolysis at conserved nucleotide-binding domains (NBDs) to diverse cellular functions. Most superfamily members are transporters, while cystic fibrosis transmembrane conductance regulator (CFTR), alone, is an ion channel. Despite this functional difference, recent results have suggested that CFTR shares a common molecular mechanism with other members. ATP binds to partial binding sites on the surface of the two NBDs, which then associate to form a NBD dimer, with complete composite catalytic sites now buried at the interface. ATP hydrolysis and γ-phosphate dissociation, with the loss of molecular contacts linking the two sides of the composite site, trigger dimer dissociation. The conformational signals generated by NBD dimer formation and dissociation are transmitted to the transmembrane domains where, in transporters, they drive the cycle of conformational changes that translocate the substrate across the membrane; in CFTR, they result in opening and closing (gating) of the ion-permeation pathway.
The disposition and effects of two doses of dichloroacetate in adults with severe falciparum malaria
Authors: KRISHNA SANJEEV , SUPANARANOND WICHAI , PUKRITTAYAKAMEE SASITHON , KUILE FEIKO TER , RUPRAH MANJIT , WHITE NICHOLAS J.
Published: October 2008

1 Dichloroacetate (DCA) is a promising treatment for lactic acidosis complicating severe malaria. The pharmacokinetics, pharmacodynamics and toxicity of dichloroacetate were evaluated in 11 patients with severe malaria, and their lactate responses compared with nine control patients in an open–label prospective study.

2 Intravenous DCA (46 mg kg‐1 infused in 30 min) or saline placebo was given on admission to the study, and 12 h later, as an adjunct to standard quinine treatment.

3 An open one‐compartment model with the following parameters described the pharmacokinetics of DCA after one dose (mean [s.d.]): v = 0.44(0.2) 1 kg‐1; CL = 0.13[0.027] 1 h‐1 kg‐1; Cmax = 106[28] mg l‐1; t1/2, = 3.4(2.2)h. After two doses of DCA (n = 9) the pharmacokinetic parameters were similar to those after the first dose.

4 DCA decreased venous plasma lactate concentrations by 42% of baseline values 8 h after admission, normalized arterial pH from a mean(s.d.) of 7.367(0.063) to 7.39(0.1), and decreased the calculated base deficit from 9.2(7.3) mEq 1‐1 to 6. 4(10.4) mEq 1‐1. In control patients lactate concentrations fell by ˜14% of baseline concentrations (P <0.02 compared with DCA recipients). Venous lactate concentrations fell a further 16% from baseline values after the second dose of DCA but this change was not significantly different from controls. There was no electrocardiographic or other evidence of toxicity associated with DCA.

5 These data suggest that a single intravenous infusion of DCA rapidly reduces hyperlactataemia in patients severely ill with malaria, and that DCA should be evaluated further as an adjunct to conventional antimalarial and supportive measures for such patients with lactic acidosis.
Persistence of anti‐hypertensive effect after ‘missed doses' of calcium antagonist with long (amlodipine) vs short (diltiazem) elimination half‐life
Authors: LEENEN FRANS H. H. , FOURNEY ANNE , NOTMAN GAIL , TANNER JOANNA
Published: October 2008

1 Calcium antagonists with long us short elimination half‐life may show marked differences in their antihypertensive effect during short interruptions of therapy by missed doses.

2 In the present study we evaluated the blood pressure lowering effect of amlodipine us diltiazem both on active maintenance treatment and after active treatment was interrupted for 2 days by placebo using a double‐blind randomized design. After a single blind placebo run‐in period, hypertensive patients were randomized to amlodipine 5 mg once daily or diltiazem 90 mg twice daily. After 4–6 weeks, doses were increased to 10 mg once daily or 180 mg twice daily, if necessary for control of diastolic blood pressure. During week 9 or 10 on active treatment blisterpacks contained 2 days of placebo. Twenty‐four hour blood pressure monitoring was performed at the end of run‐in period and during week 9 and 10 on active us interrupted therapy.

3 Active therapy by amlodipine (n = 20) lowered day systolic blood pressure by 17 ± 2 mmHg and diastolic blood pressure by 12 ± 2 mmHg and did not change heart rate. In second day of interrupted therapy most of these responses were still present. Diltiazem (n = 14) lowered day systolic blood pressure by 13 ± 2 mmHg, diastolic blood pressure by 11 ± 2 mmHg and heart rate by 10 ± 2 beats min‐1. Most of these responses had disappeared during the second day of interrupted therapy.

4 We conclude that amlodipine and diltiazem are fairly similar in lowering blood pressure from an efficacy point of view. However, during short periods of non‐compliance blood pressure control will persist markedly better with the agent with a long vs the one with a short elimination half‐life.
On the cerebro‐protective effects of caroverine, a calcium‐channel blocker and antiglutamatergic drug: double‐blind, placebo‐controlled, EEG mapping and psychometric studies under hypoxia
Authors: SALETU B. , GRÜNBERGER J. , ANDERER P. , LINZMAYER L. , KÖNIG P.
Published: October 2008

1 In a double‐blind, placebo‐controlled study, the acute antihypoxidotic properties of the calcium‐channel blocking and antiglutamatergic caroverine were investigated utilizing blood gas analysis, EEG mapping and psychometry under a transient, reversible, hypoxic hypoxidosis.

2 The latter was induced by a fixed gas combination of 9.8% oxygen (02) and 90.2% nitrogen (N2) (found in 6000 m altitude), which was inhaled for 23 min under normobaric conditions by 16 healthy, young volunteers. They received randomized after an adaptation session, single oral doses of placebo, 40, 80 and 120 mg caroverine. Evaluation of blood gases, EEG mapping and psychometry were carried out 0, 2, 4, 6 and 8 h post‐drug, during hypoxia.

3 Blood gas analysis demonstrated a drop in Po2 from 95 to 33 and 30 mmHg, in Pco2 from 38 to 30 and 30 mmHg in the 14th and 23rd minute of inhalation, respectively, while pH increased from 7.41 to 7.50 and 7.51. Base excess and standard bicarbonate remained stable.

4 EEG mapping under hypoxia exhibited a marked increase of delta/theta, decrease of alpha and an increase of superimposed beta activity, which reflects deterioration of vigilance.

5 Caroverine attenuated this hypoxia‐induced vigilance decrement in a dose‐ and time‐dependent manner 6–8 h after 80 mg and 2–8 h after 120 mg.

6 Hypoxic hypoxidosis induced a deterioration of memory and attention variability, which was mitigated by 80 and 120 mg caroverine. However, there was an augmentation of the hypoxia‐induced decrement in psychomotor performance after 120 mg.

7 The drug was well tolerated, and there were no significant differences compared with placebo with regard to pulse and blood pressure.