bluuebunny/crossref_metadata_2025 huggingface dataset:
Trophic cul‐de‐sac, Pyrazus ebeninus, limits trophic transfer through an estuarine detritus‐based food web
Authors: Bishop Melanie J. , Kelaher Brendan P. , Alquezar Ralph , York Paul H. , Ralph Peter J. , Greg Skilbeck C.
Published: January 2007

The importance to food‐webs of trophic cul‐de‐sacs, species that channel energy flow away from higher trophic levels, is seldom considered outside of the pelagic systems in which they were first identified. On intertidal mudflats, inputs of detritus from saltmarshes, macroalgae or microphytobenthos are generally regarded as a major structuring force underpinning food‐webs and there has been no consideration of trophic cul‐de‐sacs to date. A fully orthogonal three‐factor experiment manipulating the density of the abundant gastropod, Pyrazus ebeninus, detritus and macrobenthic predators on a Sydney mudflat revealed large deleterious effects of the gastropod, irrespective of detrital loading or the presence of predators. Two months after experimental manipulation, the standing‐stock of microphytobenthos in plots with high (44 per m2) densities of P. ebeninus was 20% less than in plots with low (4 per m2) densities. Increasing densities of P. ebeninus from low to high halved the abundance of macroinvertebrates and the average number of species. In contrast, the addition of detritus had differing effects on microphytobenthos (positively affected) and macroinvertebrates (negatively affected). Over the two‐months of our experiment, no predatory mortality of P. ebeninus was observed and high densities of P. ebeninus decreased impacts of predators on macroinvertebrate abundances. Given that the dynamics of southeast Australian mudflats are driven more by disturbance than seasonality in predators and their interactions with prey, it is likely that Pyrazus would be similarly resistant to predation and have negative effects on benthic assemblages at other times of the year, outside of our study period. Thus, in reducing microphytobenthos and the abundance and species richness of macrofauna, high abundances of the detritivore P. ebeninus may severely limit the flow of energy up the food chain to commercially‐important species. This study therefore suggests that trophic cul‐de‐sacs are not limited to the eutrophied pelagic systems in which they were first identified, but may exist in other systems as well.
A Direct Performance Comparison of Vaned and Vaneless Stators for Radial Turbines
Authors: Spence S. W. T. , Rosborough R. S. E. , Artt D. , McCullough G.
Published: January 2007

An extensive performance investigation has been conducted on a radial turbine with three different vaneless volutes and three corresponding vaned stators. Previously published comparisons have been based on turbines with unmatched flow rates, meaning that the impact of stator losses was not isolated from rotor and exit losses. Each vaned stator configuration tested in this investigation matched the flow rate of the corresponding vaneless volute to within 1%. The volutes and the vaned stators were all machined in order to achieve high quality and comparable surface finishes. At all operating conditions, the vaneless volutes were shown to deliver a significant efficiency advantage over the vaned stators. However, the vaneless volute turbines did not demonstrate any greater tolerance for off-design operating conditions than the vaned stator configurations. Full performance data are presented for the six different turbine configurations tested and a one-dimensional turbine performance model is evaluated as a means of predicting and extrapolating turbine performance.
Making Use of Labyrinth Interaction Flow
Authors: Pfau A. , Kalfas A. I. , Abhari R. S.
Published: January 2007

It is the aim of this publication to attract the designers attention to the end wall flow interactions of shrouded high pressure turbines. One of the key issues for designing better turbines is the understanding of the flow interactions set up by the presence of labyrinth seals. Those interaction flows are carefully examined in this publication using the control volume analysis and the radial equilibrium of forces acting on streamlines. The consequences on secondary flow development and mixing losses are discussed and quantified. Out of this insight, design recommendations are derived, which attempt to make use of the nature of the labyrinth interaction flow. The open labyrinth cavities are classified in a systematic way. The aim of this approach is to work out the characteristic differences between hub and tip cavities and those having a leakage jet or sucking main flow fluid into the labyrinth. The influence on the main flow is discussed in terms of the incidence flow angle of downstream blade rows and the associated loss production mechanisms. The design strategies presented in this paper follow two paths: (a) Optimization of the mixing losses of the leakage jets at hub and tip is estimated to result in an efficiency increase of up to 0.2%. (b) The nonaxisymmetric shaping of the labyrinth interaction flow path aims at the secondary flow control in downstream blade rows. This approach might contribute in the same magnitude of order as reduction in the mixing losses.
The Effect of Work Processes on the Casing Heat Transfer of a Transonic Turbine
Authors: Thorpe Steven J. , Miller Robert J. , Yoshino Shin , Ainsworth Roger W. , Harvey Neil W.
Published: January 2007

This paper considers the effect of the rotor tip on the casing heat load of a transonic axial flow turbine. The aim of the research is to understand the dominant causes of casing heat transfer. Experimental measurements were conducted at engine-representative Mach number, Reynolds number, and stage inlet to casing wall temperature ratio. Time-resolved heat-transfer coefficient and gas recovery temperature on the casing were measured using an array of heat-transfer gauges. Time-resolved static pressure on the casing wall was measured using Kulite pressure transducers. Time-resolved numerical simulations were undertaken to aid understanding of the mechanism responsible for casing heat load. The results show that between 35% and 60% axial chord the rotor tip-leakage flow is responsible for more than 50% of casing heat transfer. The effects of both gas recovery temperature and heat transfer coefficient were investigated separately and it is shown that an increased stagnation temperature in the rotor tip gap dominates casing heat transfer. In the tip gap the stagnation temperature is shown to rise above that found at stage inlet (combustor exit) by as much as 35% of stage total temperature drop. The rise in stagnation temperature is caused by an isentropic work input to the tip-leakage fluid by the rotor. The size of this mechanism is investigated by computationally tracking fluid path lines through the rotor tip gap to understand the unsteady work processes that occur.
Field Tests of the Solar Water Detoxification SOLWATER Reactor in Los Pereyra, Tucumán, Argentina
Authors: Navntoft Christian , Araujo Paula , Litter Marta I. , Apella María C. , Fernández Diego , Puchulu María Elena , Hidalgo Margarita del V. , Blesa Miguel A.
Published: January 2007

The SOLWATER reactor prototype is composed of two tubes containing a supported heterogeneous photocatalyst (Ahlstrom© paper impregnated with titanium dioxide), and two tubes containing a supported photosensitizer (designed and provided by G. Orellana, Universidad Complutense, Madrid, Spain). The tubes are placed on a CPC collector and run in series. Electricity is provided by a solar panel, and the recirculation rate is ca13Lmin−1. Total volume in the feed tank plus tubes is 20L. The reactor was designed and constructed by the consortium of a European research project whose objective is on the development of a fully autonomous solar reactor system to purify drinking water in remote locations of developing countries. The prototype was placed in the yard of a shanty house in Los Pereyra, Tucumán, Argentina. Water to feed the reactor is taken from the shallow aquifer through an open well. This water is contaminated with high counts of coliforms and Enterococcus faecalis. It also contains widely variable levels of Pseudomonas aeruginosa. The chemical composition of the water shows high levels of natural organic matter and of various inorganic pollutants. The reactor has been running since February 22, 2005. This paper presents the results collected in three months of operation. Around 4hr operation on a sunny day, and 5-6hr on a cloudy day are required to totally destroy fecal coliforms and Ent. faecalis. Even 24h after the experiment is concluded, no cultivable bacteria are seen by the membrane filtration method (measured colony forming units after 24hr=0). On the other hand, a small number of total coliforms remain (a few percent or less of the original count) at the end of some of the latest experiments. Possible explanations for this result are the drop in ambient temperature, the decrease in solar irradiance, and the exhaustion of the catalyst and sensitizer. P. aeruginosa is much more resistant, and only partial destruction is observed in those time intervals. The evolution of chemical parameters is also presented and discussed.
Protection against Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) Infection through Passive Transfer of PRRSV-Neutralizing Antibodies Is Dose Dependent
Authors: Lopez O. J. , Oliveira M. F. , Garcia E. Alvarez , Kwon B. J. , Doster A. , Osorio F. A.
Published: January 2007

Previous work in our laboratory demonstrated that passive transfer of porcine reproductive and respiratory syndrome virus (PRRSV)-neutralizing antibodies (NA) protected pregnant sows against reproductive failure and conferred sterilizing immunity in sows and offspring. We report here on the dose requirement for protection by passive transfer with NA in young weaned pigs. The presence of a 1:8 titer of PRRSV-NA in serum consistently protected pigs against viremia. Nevertheless, their lungs, tonsils, buffy coat cells, and peripheral lymph nodes contained replicating PRRSV similar to the infected control group. Likewise, these animals excreted infectious virus to sentinels similar to the infectivity control animals. In an attempt to reach complete protective immunity equivalent to that previously observed in sows, the pigs were transferred with a higher titer of PRRSV-NA (1:32), and even then apparent sterilizing immunity was attained in only 50% of the animals. In conclusion, the presence of anti-PRRSV-NA in serum with a titer of 1:8 is enough to block viremia but not peripheral tissue seeding and transmission to contact animals. While a relatively low level of NA in blood is capable of conferring sterilizing immunity against PRRSV in sows, the amount of NA necessary to obtain full protection of a young weaned pig would be significantly higher, suggesting that differences exist in the PRRSV pathogenesis between both age groups. In addition, the titer of NA could be a helpful parameter of protection in the assessment of PRRSV vaccines.
Identification of Alpha-Hemolytic Streptococci by Pyrosequencing the 16S rRNA Gene and by Use of VITEK 2
Authors: Haanperä Marjo , Jalava Jari , Huovinen Pentti , Meurman Olli , Rantakokko-Jalava Kaisu
Published: January 2007

Alpha-hemolytic streptococci are very difficult to identify by phenotypic methods. In this study, a pyrosequencing method for the identification of streptococcal species based on two variable regions of the 16S rRNA gene is described. Almost all studied streptococcal species (n= 51) represented by their type strains could be differentiated except for some closely related species of theStreptococcus bovisorS. salivariusgroup. The pyrosequencing results of alpha-hemolytic streptococci isolated from blood (n= 99) or from the normal pharyngeal microbiota (n= 25) were compared to the results obtained by the VITEK 2 with GP card (bioMérieux, Marcy l'Etoile, France). As expected, the results of the two methods did not completely agree, but 93 (75.0%) of the isolates assigned to the same streptococcal group by both methods and 57 (46.0%) reached consistent results at the species level. However, 10 strains remained unidentified by VITEK 2, and 4 isolates could not be assigned to any streptococcal group by pyrosequencing. Identification of members of theS. mitisandS. sanguinisgroups proved difficult for both methods. Furthermore, the pyrosequencing analysis revealed great sequence variation, since only 43 (32.3%) of the 133 isolates analyzed by pyrosequencing had sequences identical to a type strain. The variation was greatest in the pharyngeal isolates, slightly lower in the blood culture isolates, and nonexistent in invasive pneumococcal isolates (n= 17) that all had theS. pneumoniaetype strain sequence. The resolution of the results obtained by the two methods is impeded by the lack of a proper gold standard.
The MyD116 African Swine Fever Virus Homologue Interacts with the Catalytic Subunit of Protein Phosphatase 1 and Activates Its Phosphatase Activity
Authors: Rivera José , Abrams Charles , Hernáez Bruno , Alcázar Alberto , Escribano José M. , Dixon Linda , Alonso Covadonga
Published: January 2007

The DP71L protein of African swine fever virus (ASFV) shares sequence similarity with the herpes simplex virus ICP34.5 protein over a C-terminal domain. We showed that the catalytic subunit of protein phosphatase 1 (PP1) interacts specifically with the ASFV DP71L protein in a yeast two-hybrid screen. The chimeric full-length DP71L protein, from ASFV strain Badajoz 71 (BA71V), fused to glutathione
S
-transferase (DP71L-GST) was expressed in
Escherichia coli
and shown to bind specifically to the PP1-α catalytic subunit expressed as a histidine fusion protein (6×His-PP1α) in
E. coli
. The functional effects of this interaction were investigated by measuring the levels of PP1 and PP2A in ASFV-infected Vero cells. This showed that infection with wild-type ASFV strain BA71V activated PP1 between two- and threefold over that of mock-infected cells. This activation did not occur in cells infected with the BA71V isolate in which the DP71L gene had been deleted, suggesting that expression of DP71L leads to PP1 activation. In contrast, no effect was observed on the activity of PP2A following ASFV infection. We showed that infection of cells with wild-type BA71V virus resulted in decreased phosphorylation of the α subunit of eukaryotic initiation factor 2 (eIF-2α). ICP34.5 recruits PP1 to dephosphorylate the α subunit of eukaryotic translational initiation factor 2 (also known as eIF-2α); possibly the ASFV DP71L protein has a similar function.
In Vitro Study of the Effects of Precore and Lamivudine-Resistant Mutations on Hepatitis B Virus Replication
Authors: Heipertz Richard A. , Miller Thomas G. , Kelley Colleen M. , Delaney William E. , Locarnini Stephen A. , Isom Harriet C.
Published: January 2007

Understanding the consequences of mutation in the hepatitis B virus (HBV) genome on HBV replication is critical for treating chronic HBV infection. In this study, HBV replication in HepG2 cells initiated by transduction with precore (PC), rtM204I, and wild-type (wt) HBV recombinant baculoviruses was compared. The pattern and magnitude of HBV replication initiated by the PC HBV recombinant baculovirus were similar to those observed for wt HBV throughout the time course examined. In contrast, when the rtM204I mutation was introduced into wt HBV, by day 10 postinfection the levels of intra- and extracellular HBV DNA were markedly reduced compared to those for wt HBV. Although the rtM204I mutation reduced the production of HBV replicative intermediates, no effect on the level of covalently closed circular DNA or HBV transcripts was observed at late time points. Coinfection studies with different ratios of wt and rtM204I baculoviruses showed that the rtM204I variant did not produce a product that inhibited HBV replication. However, the combination of the wt and rtM204I baculoviruses yielded HBV DNA levels at late time points that were greater than those for the wt alone, suggesting that wt polymerase may function intransto boost rtM204I replication. We concluded that the rtM204I mutation generates a polymerase that is not only resistant to lamivudine but also replicates nucleic acids to lower levels in vitro.
p53-Independent Endoplasmic Reticulum Stress-Mediated Cytotoxicity of a Newcastle Disease Virus Strain in Tumor Cell Lines
Authors: Fábián Zsolt , Csatary Christine M. , Szeberényi József , Csatary Laszlo K.
Published: January 2007

While Newcastle disease virus (NDV) causes serious infections in birds, it is apparently nonpathogenic in mammalian species, including humans. Previous observations and small-scale clinical trials indicated that NDV exerts oncolytic effects. Isolates of NDV were found to have selective affinity to transformed cells. We previously showed that the attenuated NDV strain MTH-68/H causes apoptotic cell death in cultures of PC12 rat pheochromocytoma cells. The aim of the present study was to extend MTH-68/H cytotoxicity testing with human tumor cell lines and to analyze certain biochemical aspects of its oncolytic effect. MTH-68/H was found to be able to kill a wide range of transformed cells by apoptosis. While caspase-8 and caspase-9 are not involved in MTH-68/H-induced apoptosis, activation of caspase-3 and caspase-12 was detected in virus-infected PC12 cells. A human glioblastoma cell line with repressible expression of the p53 protein did not show any difference in MTH-68/H sensitivity in its p53-expressing and p53-depleted states, indicating that the apoptotic process induced by MTH-68/H does not depend on p53. Apoptosis was accompanied by virus replication in two tumor cell lines tested (PC12 cells and HeLa human cervical cells), and signs of endoplasmic reticulum stress (phosphorylation of protein kinase R-like endoplasmic reticulum kinase and eIF2α) were also detected in transformed cells. In contrast, proliferation of nontransformed mouse and rat fibroblast cell lines and human primary fibroblasts was not affected by MTH-68/H treatment. MTH-68/H thus selectively kills tumor cell cultures by inducing endoplasmic reticulum stress leading to p53-independent apoptotic cell death.
Comparison of Weibull and normal distributions for concrete compressive strengths
Authors: Tumidajski P J , Fiore L , Khodabocus T , Lachemi M , Pari R
Published: January 2007

For concrete produced in a commercial ready mix operation, the compressive strengths were fitted to Weibull and normal distributions. It was found that the Weibull distribution successfully describes concrete compressive strength failure data. This information is useful in the theoretical description of concrete failure. Furthermore, based on chi-squared, Anderson–Darling and Kolmogorov-Smirnov goodness-of-fit tests, the difference between the Weibull and normal distribution is not large enough to make a clear distinction regarding which distribution definitively fits the experimental data better. Key words: compressive strength, normal distribution, Weibull distribution, goodness-of-fit.
Characterization of the vasorelaxation to methanandamide in rat gastric arteries
Authors: Breyne Joke , Van de Voorde Johan , Vanheel Bert
Published: January 2007

In the present study, the relaxant effect of the cannabinoid methanandamide was explored in rat gastric arteries. Since in some vessels cannabinoids have been shown to release calcitonin gene-related peptide (CGRP) from perivascular nerves, the influence of methanandamide was compared with that of exogenous CGRP. Methanandamide and CGRP elicited concentration-dependent, endothelium-independent relaxations. Methanandamide-induced relaxations were unaffected by the CB1receptor antagonist AM251, the CB2receptor antagonists AM630 and SR144528, and combined pre-exposure to AM251 and SR144528. Pre-exposure to O-1918, an antagonist of a novel nonCB1/nonCB2cannabinoid receptor, did not influence the relaxations to methanandamide. Capsaicin or capsazepine treatment slightly inhibited methanandamide-induced relaxations. Preincubation with 30 mmol/L extracellular K+or 3 mmol/L TEA had no significant effect on the responses elicited by methanandamide, but reduced CGRP-induced relaxations. Relaxation to 10−5mol/L methanandamide was significantly blunted by Bay K8644 and by preincubation with nifedipine. Furthermore, 10−5mol/L methanandamide significantly inhibited CaCl2-induced contractions in norepinephrine-stimulated vessels previously depleted of intra- and extracellular Ca2+. Finally, preincubation with 10−5mol/L methanandamide almost completely abolished high K+-induced contractions. These findings suggest that the vasorelaxant action of methanandamide in rat gastric arteries is not mediated by stimulation of known cannabinoid receptors and only partly related to stimulation of TRPV1receptors on perivascular nerves. At high concentrations, methanandamide might induce relaxation by reducing calcium entry into the smooth muscle cells.
SCALING PHENOMENA IN THE SLOPE SYSTEM
Authors: SHIN JAE KYUN , CHOI SEUNG RYUL
Published: January 2007

An agent-based model is applied for studying the group-forming behavior numerically. A fixed number of homogeneous agents are distributed on a two-dimensional square lattice system with L × L unit cells. The dynamics of the agents are described in terms of a potential and a friction factor, just like that of a weight on a slope. The potential is defined in an attempt to model the concept of the "biosocial attraction." Depending on the density of the population and the friction factor, four regimes of group-size distributions are identified. They are the fixed, the exponential, the power-law and the black-hole regimes. Especially, beyond the well-known exponential and power-law distributions, a black-hole regime is identified for the lowest values of the friction factor. In the black-hole regime, all the agents in the system are attracted to the only group remaining in the system. An example membership values for each of the four classes are suggested in terms of the two key parameters of the system, the population density and the friction factor. And a phase transition is observed between the exponential and the black-hole regimes. Also the results are discussed in relation to the city-size distributions in a country.
FRACTAL CRACK PATTERNS IN LAPONITE FILMS AND THEIR SCALING BEHAVIOR
Authors: MAL DIBYENDU , SINHA SUPARNA , DUTTA TAPATI , MITRA S. , TARAFDAR SUJATA
Published: January 2007

We study crack patterns in laponite films of different thickness. The patterns show a self-similarity under coarse-graining, the fractal dimension determined by box-counting has a value around 1.66, independent of film thickness. The cracks on layers of different thickness show a remarkable scaling bahavior. We have measured the cumulative area covered by the cracks versus minimum crack-width resolved. Curves representing crack area for different thickness collapse onto a single curve, when the crack widths are scaled by the film thickness.
A NEW TECHNIQUE ESTIMATING LOCATION OF MEAN JOINT CENTERS OF ROTATION WITH ASSOCIATED DISPERSIONS AND ASSESSING TO FUNCTIONAL COORDINATE SYSTEM OF MOVING LIMB SEGMENTS
Authors: BERTHONNAUD ERIC , DIMNET JOANNÈS
Published: January 2007

Joint centers are obtained from data treatment of a set of markers placed on the skin of moving limb segments. Finite helical axis (FHA) parameters are calculated between time step increments. Artifacts associated with nonrigid body movements of markers entail ill-determination of FHA parameters. Mean centers of rotation may be calculated over the whole movement, when human articulations are likened to spherical joints. They are obtained using numerical technique, defining point with minimal amplitude, during joint movement. A new technique is presented. Hip, knee, and ankle mean centers of rotation are calculated. Their locations depend on the application of two constraints. The joint center must be located next to the estimated geometric joint center. The geometric joint center may migrate inside a cube of possible location. This cube of error is located with respect to the marker coordinate systems of the two limb segments adjacent to the joint. Its position depends on the joint and the patient height, and is obtained from a stereoradiographic study with specimen. The mean position of joint center and corresponding dispersion are obtained through a minimization procedure. The location of mean joint center is compared with the position of FHA calculated between different sequential steps: time sequential step, and rotation sequential step where a minimal rotation amplitude is imposed between two joint positions. Sticks are drawn connecting adjacent mean centers. The animation of stick diagrams allows clinical users to estimate the displacements of long bones (femur and tibia) from the whole data set.
A NEW BIOMECHANICAL HEAD INJURY CRITERION
Authors: BABBS CHARLES F.
Published: January 2007

This paper presents a new analysis of the physics of closed head injury caused by intense acceleration of the head. At rest a 1 cm gap filled with cerebrospinal fluid (CSF) separates the adult human brain from the skull. During impact, whole head acceleration induces artificial gravity within the skull. Because its density differs slightly from that of CSF, the brain accelerates, strikes the inner aspect of the rigid skull, and undergoes viscoelastic deformation. Analytical methods for a lumped parameter model of the brain predict internal brain motions that correlate well with published high-speed photographic studies. The same methods predict a truncated hyperbolic strength-duration curve for impacts that produce a given critical compressive strain. A family of such curves exists for different critical strains. Each truncated hyperbolic curve defines a head injury criterion (HIC) or threshold for injury, which is little changed by small offsetting corrections for curvature of the brain and for viscous damping. Such curves predict results of experimental studies of closed head injury, known limits for safe versus dangerous falls, and the relative resistance of smaller versus larger animals to acceleration of the head. The underlying theory provides improved understanding of closed head injury and better guidance to designers of protective equipment and to those extrapolating research results from animals to man.
THE EFFECT OF HYPODERMIC NEEDLE PERFORATIONS ON THE TENSILE PROPERTIES OF CHICKEN TENDONS
Authors: CHOU S. M. , ZHAI L. Y. , YEOH E. S. H.
Published: January 2007

Corticosteroid injection using hypodermic needles is one of the commonly accepted treatments for patients with hand conditions. However, in some cases the needle perforations may cause tendon ruptures. This paper aims to investigate the relationships between a tendon's ultimate tensile strength (UTS) and the number of hypodermic needle perforations as well as needle sizes. The UTS was determined for all specimens at the loading rate of 0.4 mm/s. Tendon specimens with perforations punctured by large-sized (19 G) hypodermic needles were found to have significantly lower UTS than those with perforations punctured by medium-sized (23 G) and small-sized (27 G) needles. For specimens punctured by medium- and small-sized needles, no significant difference in UTS was observed between tendons with three perforations and those with one perforation.
ANALYSIS OF THE VIRTUAL ELECTRODE PHENOMENA USING BIDOMAIN MODEL: BASIC CHARACTERISTICS FOR PASSIVE MEMBRANE
Authors: SUZUKI TOHRU , SATO SHUNSUKE , OHE TOHRU , SUZUKI RYOJI , KAJIYA FUMIHIKO
Published: January 2007

The virtual electrode (VE) has been recognized as an important factor for success or failure of cardiac defibrillation. Many researches have been performed to study characteristics of the VE. However, there are some questions which remain unanswered. In this study, we developed a simulator to solve a three-dimensional bidomain model and performed several simulations to elucidate the basic characteristics of VE in a simplified cardiac tissue with passive membrane when a constant unipolar cathodal stimulus was applied. The results showed that for smaller electrodes, VE has a typical dog-bone shaped virtual cathode (VC) and two egg-shaped virtual anodes (VAs). The distributions both in intra- and extracellular potentials have concentric ellipsoidal isosurfaces, but their ellipticities are subtly different, producing VE. For larger electrodes, VC becomes larger and has a flat-dish shape rather than dog-bone, and VA becomes smaller and also flattens and collapses. The peak values of VE are larger for smaller electrodes, but their time courses show similar tendency among the different sized electrodes. The change of stimulus strength and polarity only affects the magnitude of VE in a linear manner and the distribution pattern is unchanged. These results provide us fundamental knowledge about VE.
DETECTION OF DAILY PHYSICAL ACTIVITIES IN THE TIME–FREQUENCY DOMAIN
Authors: NYAN M. N. , TAY FRANCIS E. H. , SEAH K. H. W. , ISMAIL N. H.
Published: January 2007

A new method of physical activity monitoring that is able to detect posture transitions using two acceleration signals attached on the shoulder part of a garment is presented. Posture transition activities in continuous accelerometer records were classified into two steps. In the first step, wavelet-reconstructed antero-posterior acceleration signal was applied to extract the transition segments from the continuous accelerometer record. When compared with the reference system in segment extraction, averaged absolute error 0.21 s for sit–stand posture transitions and 0.26 s for stand–sit posture transitions were achieved. The overall sensitivity and specificity of sit–stand posture transitions were 90.852% and 98.98% and those of stand–sit posture transitions were 91.367% and 98.55%. In the second step, wavelet coefficients of extracted segments of vertical acceleration signals were used as features in classification. The classification rate (segments that are extracted and classified correctly/total number of segments) of sit–stand and stand–sit activities are 93.65% and 95.24%, respectively. Our results proved a reliable technique of detecting posture transition activities in physical activity monitoring.
QUANTUM COMPUTATION WITH ABELIAN ANYONS ON THE HONEYCOMB LATTICE
Authors: PACHOS JIANNIS K.
Published: January 2007

We consider a two-dimensional spin system that exhibits Abelian anyonic excitations. Manipulations of these excitations enable the construction of a quantum computational model. While the one-qubit gates are performed dynamically, the model offers the advantage of having a two-qubit gate that is of topological nature. The transport and braiding of anyons on the lattice can be performed adiabatically enjoying the robust characteristics of geometrical evolutions. The same control procedures can be used when dealing with non-Abelian anyons. A possible implementation of the manipulations with optical lattices is developed.
RAW-DATA ATTACKS IN QUANTUM CRYPTOGRAPHY WITH PARTIAL TOMOGRAPHY
Authors: ASSAD SYED M. , SUZUKI JUN , ENGLERT BERTHOLD-GEORG
Published: January 2007

We consider a variant of the BB84 protocol for quantum cryptography, the prototype of tomographically incomplete protocols, where the key is generated by one-way communication rather than the usual two-way communication. Our analysis, backed by numerical evidence, establishes thresholds for eavesdropping attacks on the raw data and on the generated key at quantum bit error rates of 10% and 6.15%, respectively. Both thresholds are lower than the threshold for unconditional security in the standard BB84 protocol.
TOPOS-THEORETIC CLASSIFICATION OF QUANTUM EVENTS STRUCTURES IN TERMS OF BOOLEAN REFERENCE FRAMES
Authors: ZAFIRIS ELIAS
Published: January 2007

We construct a sheaf-theoretic representation of quantum events structures, in terms of Boolean localization systems. These covering systems are constructed as ideals of structure-preserving morphisms of quantum event algebras from varying Boolean domains, identified with physical contexts of measurement. The modeling sheaf-theoretic scheme is based on the existence of a categorical adjunction between presheaves of Boolean event algebras and quantum event algebras. On the basis of this adjoint correspondence, we also prove the existence of an object of truth values in the category of quantum logics, characterized as subobject classifier. This classifying object plays the equivalent role that the two-valued Boolean truth values object plays in classical events structures. We construct the object of quantum truth values explicitly, and furthermore, demonstrate its functioning for the valuation of propositions in a typical quantum measurement situation.
NONASSOCIATIVE GEOMETRY: FRIEDMANN–ROBERTSON–WALKER SPACETIME
Authors: NESTEROV ALEXANDER I. , SABININ LEV V.
Published: January 2007

In (Phys. Rev. D62 (2000) 081501(R)) we proposed a unified description of continuum and discrete spacetime based on nonassociative geometry. It follows from our approach that at distances comparable with Planck length the standard concept of spacetime might be replaced by the nonassociative discrete structure, and nonassociativity is the algebraic equivalent of the curvature. In the framework of the nonassociative geometry we introduce discrete Friedmann–Robertson–Walker (FRW) model and show that the standard FRW spacetime appears as its 'continuum limit'.
GENERAL RELATIVITY AS A CONSTRAINED GAUGE THEORY
Authors: VIGNOLO STEFANO , CIANCI ROBERTO , BRUNO DANILO
Published: January 2007

The formulation of General Relativity presented in [1] and the Hamiltonian formulation of Gauge theories described in [2] are made to interact. The resulting scheme allows to see General Relativity as a constrained Gauge theory.
4-D GEOMETRICAL MODELING OF MATERIAL AGING
Authors: CHUDNOVSKY ALEXANDER , PRESTON SERGE
Published: January 2007

The 4-dim intrinsic (material) Riemannian metric G of the material 4-D space-time continuum P is utilized as the characteristic of the aging processes developing in the material. Manifested through variation of basic material characteristics such as density, moduli of elasticity, yield stress, strength, and toughness., the aging process is modeled as the evolution of the metric G (most importantly of its time component G00) of the material space-time P embedded into 4-D Newtonian space-time with a Euclidean metric.

The evolutional equation for the metric G is derived by the classical variational approach. Construction of the Lagrangian for an aging elastic medium and the derivation of a system of coupled elastostatic and aging equations constitute the central part of the work. The external and internal balance laws associated with symmetries of material and physical space-time geometries are briefly reviewed from a new viewpoint.
GAUGE-NATURAL PARAMETRIZED VARIATIONAL PROBLEMS, VAKONOMIC FIELD THEORIES AND RELATIVISTIC HYDRODYNAMICS OF A CHARGED FLUID
Authors: BIBBONA E. , FATIBENE L. , FRANCAVIGLIA M.
Published: January 2007

Variational principles for field theories where variations of fields are restricted along a parametrization are considered. In particular, gauge-natural parametrized variational problems are defined as those in which both the Lagrangian and the parametrization are gauge covariant and some further conditions are satisfied in order to formulate a Nöther theorem that links horizontal and gauge symmetries to the relative conservation laws (generalizing what Fernández, García and Rodrigo did in some recent papers). The case of vakonomic constraints in field theory is also studied within the framework of parametrized variational problems, defining and comparing two different concepts of criticality of a section, one arising directly from the vakonomic schema, the other making use of an adapted parametrization. The general theory is then applied to the case of hydrodynamics of a charged fluid coupled with its gravitational and electromagnetic field. A variational formulation including conserved currents and superpotentials is given that turns out to be computationally much easier than the standard one.
ON A SPECTRAL THEOREM FOR DEFORMATION QUANTIZATION
Authors: FEDOSOV B.
Published: January 2007

We give a construction of an eigenstate for a non-critical level of the Hamiltonian function, and investigate the contribution of Morse critical points to the spectral decomposition. We compare the rigorous result with the series obtained by a perturbation theory. As an example the relation to the spectral asymptotics is discussed.
ASSESSMENT OF TRANSPORT POLICIES TOWARD FUTURE EMISSION TARGETS: A BACKCASTING APPROACH FOR STOCKHOLM 2030
Authors: ROBÈRT MARKUS , JONSSON R. DANIEL
Published: January 2007

Stockholm has set a target for greenhouse gas emissions in the year 2030, based on the United Nation's (IPCC) recommendations for an acceptable CO2level in the atmosphere. In this study we use a backcasting framework to analyze a range of specific transport policies and fuel technology related developments with respect to the emission target. Our study employs a transport modelling system, traditionally used for forecasts, to quantify the impacts of various travel demand measures (TDM). Our study shows that the change in travel demand, induced by various travel policies, will not suffice on its own to reach the target. Even if fuel price is tripled, a substantial share of renewable fuels is required for target achievement. While our study shows that travel demand measures have a fairly small effect on CO2emissions, it also hints at other compelling reasons for introducing such measures. Constructive strategies for the transport system would not only contribute to reduce risks with climate change. Even small reductions of transport volumes might imply large socio economic savings in traffic related costs, reduced emissions of substances with health impacts, fewer accidents, shorter travel times and higher travel time reliability. These aspects are arguably all part of a sustainable transport development.
New Insights into the Mechanism of Action of Amphetamines
Authors: Fleckenstein Annette E. , Volz Trent J. , Riddle Evan L. , Gibb James W. , Hanson Glen R.
Published: January 2007

Amphetamine is a psychostimulant commonly used to treat several disorders, including attention deficit, narcolepsy, and obesity. Plasmalemmal and vesicular monoamine transporters, such as the neuronal dopamine transporter and the vesicular monoamine transporter-2, are two of its principal targets. This review focuses on new insights, obtained from both in vivo and in vitro studies, into the molecular mechanisms whereby amphetamine, and the closely related compounds methamphetamine and methylenedioxymethamphetamine, cause monoamine, and particularly dopamine, release. These mechanisms include amphetamine-induced exchange diffusion, reverse transport, and channel-like transport phenomena as well as the weak base properties of amphetamine. Additionally, amphetamine analogs may affect monoamine transporters through phosphorylation, transporter trafficking, and the production of reactive oxygen and nitrogen species. All of these mechanisms have potential implications for both amphetamine- and methamphetamine-induced neurotoxicity, as well as dopaminergic neurodegenerative diseases.
Circadian Rhythms: Mechanisms and Therapeutic Implications
Authors: Levi Francis , Schibler Ueli
Published: January 2007

The mammalian circadian system is organized in a hierarchical manner in that a central pacemaker in the suprachiasmatic nucleus (SCN) of the brain's hypothalamus synchronizes cellular circadian oscillators in most peripheral body cells. Fasting-feeding cycles accompanying rest-activity rhythms are the major timing cues in the synchronization of many, if not most, peripheral clocks, suggesting that the temporal coordination of metabolism and proliferation is a major task of the mammalian timing system. The inactivation of noxious food components by hepatic, intestinal, and renal detoxification systems is among the metabolic processes regulated in a circadian manner, with the understanding of the involved clock output pathways emerging. The rhythmic control of xenobiotic detoxification provides the molecular basis for the dosing time-dependence of drug toxicities and efficacy. This knowledge can in turn be used in improving or designing chronotherapeutics for the patients who suffer from many of the major human diseases.
Dual effect of thapsigargin on cell death in porcine aortic smooth muscle cells
Authors: Chin Ting-Yu , Lin Hsiu-Chen , Kuo Ju-Ping , Chueh Sheau-Huei
Published: January 2007

A sustained increase in the cytosolic Ca2+ concentration ([Ca2+]i) can cause cell death. In this study, we found that, in cultured porcine aortic smooth muscle cells, endoplasmic reticulum (ER) stress, triggered by depletion of Ca2+ stores by thapsigargin (TG), induced an increase in the [Ca2+]i and cell death. However, the TG-induced death was not related to the [Ca2+]i increase but was mediated by targeting of activated Bax to mitochondria and the opening of mitochondrial permeability transition pores (PTPs). Once the mitochondrial PTPs had opened, several events, including collapse of the mitochondrial membrane potential, cytochrome c release, and caspase-3 activation, occurred and the cells died. TG-induced cell death was completely inhibited by the pan-caspase inhibitor Z-VAD-fmk and was enhanced by the Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane- N,N,N′,N′-tetraacetic acid (BAPTA), suggesting the existence of a Ca2+-dependent anti-apoptotic mechanism. After TG treatment, Ca2+-sensitive mitogen-activated protein kinase (MAPK) activation was induced and acted as a downstream effector of phosphatidylinositol 3-kinase (PI 3-kinase). The protective effect of Z-VAD-fmk on TG-induced cell death was reversed by BAPTA, PD-098059 (an MAPK kinase inhibitor), or LY-294002 (a PI 3-kinase inhibitor). Taken together, our data indicate that ER stress simultaneously activate two pathways, the mitochondrial caspase-dependent death cascade and the Ca2+-dependent PI 3-kinase/MAPK anti-apoptotic machinery. The Bax activation and translocation, but not the [Ca2+]i increase, may activate mitochondrial PTPs, which, in turn, causes activation of caspases and cell death, whereas Ca2+-dependent MAPK activation counteracts death signaling; removal of Ca2+ activated a second caspase-independent death pathway.
Actin-dependent regulation of connective tissue growth factor
Authors: Muehlich Susanne , Cicha Iwona , Garlichs Christoph D. , Krueger Bettina , Posern Guido , Goppelt-Struebe Margarete
Published: January 2007

Expression of connective tissue growth factor (CTGF) in endothelial cells is modulated by shear stress affecting the organization of the cytoskeleton. The molecular connection between alterations of actin and CTGF expression was investigated in human umbilical vein endothelial cells (HUVEC) and a microvascular endothelial cell line. Overexpression of nonpolymerizable monomeric actin R62D interfered with stress fiber formation in HUVEC and concomitantly reduced immunoreactive CTGF. In microvascular endothelial cells, flow-dependent upregulation of CTGF was prevented by this actin mutant. In contrast, overexpression of actin S14C strengthened filamentous actin and increased CTGF expression. These data indicated an inverse relationship between CTGF expression and monomeric actin. Coexpression of the mutant actins and different CTGF promoter constructs revealed an actin-sensitive site between 3 and 4.5 kb of the CTGF promoter. A CArG-like box at −3791 bp was responsible for actin-dependent CTGF induction as shown by mutagenesis. Overexpression of actin S14C activated the nonmutated promoter significantly more strongly than the mutated promoter. Actin polymerization is regulated by the small GTPase RhoA and activation of serum response factor (SRF). Overexpression of constitutively active RhoA or SRF significantly increased CTGF protein synthesis. The 4.5-kb promoter construct, but not the construct with a mutation in the CArG box, was activated by SRF or RhoA, providing evidence for a functional role of this site in CTGF induction. These findings provide novel evidence that monomeric actin is the connecting link between alterations in the cytoskeleton and CTGF gene expression and demonstrate the importance of SRF in regulating CTGF transcription.
Absence of selective brain cooling in unrestrained baboons exposed to heat
Authors: Maloney Shane K. , Mitchell Duncan , Mitchell Graham , Fuller Andrea
Published: January 2007

To test whether baboons are capable of implementing selective brain cooling, we measured, every 5 min, the temperature in their hypothalamus, carotid arterial bloodstream, and abdominal cavity. The baboons were unrestrained and exposed to 22°C for 7 days and then to a cyclic environment with 15°C at night and 35°C during the day for a further 7 days. During the latter 7 days some of the baboons also were exposed to radiant heat during the day. For three days, during heat exposure, water was withheld. At no time was the hypothalamus cooler than carotid arterial blood, despite brain temperatures above 40°C. With little variation, the hypothalamus was consistently 0.5°C warmer than arterial blood. At high body temperatures, the hypothalamus was sometimes cooler than the abdomen. Abdominal temperature was more variable than arterial blood and tended to exceed arterial blood temperature at higher body temperatures. Hypothalamic temperature cooler than a warm abdomen is not evidence for selective brain cooling. In species that can implement selective brain cooling, the brain is most likely to be cooler than carotid arterial blood when an animal is hyperthermic, during heat exposure, and also dehydrated and undisturbed by human presence. When we exposed baboons to high ambient temperatures while they were water deprived and undisturbed, they never implemented selective brain cooling. We conclude that baboons cannot implement selective brain cooling and can find no convincing evidence that any primate species can do so.
Evidence that postprandial reduction of renal calcium reabsorption mediates hypercalciuria of patients with calcium nephrolithiasis
Authors: Worcester Elaine M. , Gillen Daniel L. , Evan Andrew P. , Parks Joan H. , Wright Katrina , Trumbore Linda , Nakagawa Yasushi , Coe Fredric L.
Published: January 2007

Idiopathic hypercalciuria (IH) is common among calcium stone formers (IHSF). The increased urinary calcium arises from increased intestinal absorption of calcium, but it is unclear whether increased filtered load or decreased renal tubular reabsorption of calcium is the main mechanism for the increased renal excretion. To explore this question, 10 IHSF and 7 normal subjects (N) were studied for 1 day. Urine and blood samples were collected at 30- to 60-min intervals while subjects were fasting and after they ate three meals providing known amounts of calcium, phosphorus, sodium, protein, and calories. Fasting and fed, ultrafiltrable calcium levels, and filtered load of calcium did not differ between N and IHSF. Urine calcium rose with meals, and fractional reabsorption fell in all subjects, but the change was significantly higher in IHSF. The changes in calcium excretion were independent of sodium excretion. Serum parathyroid hormone levels did not differ between N and IHSF, and they could not account for the greater fall in calcium reabsorption in IHSF. Serum magnesium and phosphorus levels in IHSF were below N throughout the day, and tubule phosphate reabsorption was lower in IHSF than N after meals. The primary mechanism by which kidneys ferry absorbed calcium into the urine after meals is via reduced tubule calcium reabsorption, and IHSF differ from N in the magnitude of the response. Parathyroid hormone is not likely to be a sufficient explanation for this difference.