bluuebunny/crossref_metadata_2025 huggingface dataset:
The accumulation of silver in marine sediments: A link to biogenic Ba and marine productivity
Authors: McKay J. L. , Pedersen T. F.
Published: November 2008

The concentrations of Ag and a suite of redox‐sensitive trace metals (Re, Cd, and Mo) were measured in surface sediments from the Western Canadian, Mexican, Peruvian, and Chilean continental margins. In all regions, Ag content increases from ∼80 ng g−1 (i.e., lithogenic values) on the shelf up to as high as 1483 ng g−1 on the lower slope. However, the trend of increasing Ag with increasing water depth breaks down at deepwater sites (>2500 m) where only lithogenic concentrations are documented. Silver content does not correlate with the distributions of redox‐sensitive trace metals, suggesting that sedimentary redox conditions are not the primary control on Ag accumulation. Instead, a positive correlation between Ag and Ba in surface and near‐surface sediments suggests that Ag is scavenged by and delivered to the sediment with the organic particle flux. Scavenging probably results from the precipitation of Ag2S within the organic particles due to the development of anoxia and sulfate reduction. If this hypothesis is correct, then Ag has the potential to be a paleoproductivity proxy.
Spatial variability of glacier elevation changes in the Swiss Alps obtained from two digital elevation models
Authors: Paul Frank , Haeberli Wilfried
Published: November 2008

Massive glacier thinning in the Alps during the past 20 years is documented by direct mass balance measurements on nine regularly observed glaciers. How representative this limited sample of glaciers is for the entire Alps, however, remained uncertain. The near‐global digital terrain model from the SRTM enables a closer analysis of this question, which is of fundamental importance to assess overall glacier volume change. Here we present elevation changes from 1985 to 1999 for about 1050 glaciers in the Swiss Alps. The analysis reveals extreme thickness losses (>80 m) for flat/low‐lying glacier tongues and a strong overall surface lowering. The mean cumulative mass balance of the nine glaciers with direct measurements (−10.8 m w.e.) agrees well with the mean change of the entire region from DEM differencing (−11 m w.e.) and can thus be considered to be representative. Mean thickness change of individual glaciers is correlated with their size, elevation, and exposure to solar irradiation. This implies that mass losses of large glaciers can be underestimated when they are directly inferred from values measured at much smaller glaciers.
Suprathermal electron evolution in a Parker spiral magnetic field
Authors: Owens M. J. , Crooker N. U. , Schwadron N. A.
Published: November 2008

Suprathermal electrons (>70 eV) form a small fraction of the total solar wind electron density but serve as valuable tracers of heliospheric magnetic field topology. Their usefulness as tracers of magnetic loops with both feet rooted on the Sun, however, most likely fades as the loops expand beyond some distance owing to scattering. As a first step toward quantifying that distance, we construct an observationally constrained model for the evolution of the suprathermal electron pitch‐angle distributions on open field lines. We begin with a near‐Sun isotropic distribution moving antisunward along a Parker spiral magnetic field while conserving magnetic moment, resulting in a field‐aligned strahl within a few solar radii. Past this point, the distribution undergoes little evolution with heliocentric distance. We then add constant (with heliocentric distance, energy, and pitch angle) ad‐hoc pitch‐angle scattering. Close to the Sun, pitch‐angle focusing still dominates, again resulting in a narrow strahl. Farther from the Sun, however, pitch‐angle scattering dominates because focusing is effectively weakened by the increasing angle between the magnetic field direction and intensity gradient, a result of the spiral field. We determine the amount of scattering required to match Ulysses observations of strahl width in the fast solar wind, providing an important tool for inferring the large‐scale properties and topologies of field lines in the interplanetary medium. Although the pitch‐angle scattering term is independent of energy, time‐of‐flight effects in the spiral geometry result in an energy dependence of the strahl width that is in the observed sense although weaker in magnitude.
An improved comparison of atmospheric Ar/N2 time series and paired ocean‐atmosphere model predictions
Authors: Cassar Nicolas , McKinley Galen A. , Bender Michael L. , Mika Robert , Battle Mark
Published: November 2008

Ar/N2 variations in the atmosphere reflect ocean heat fluxes, air‐sea gas exchange, and atmospheric dynamics. Here atmospheric Ar/N2 time series are compared to paired ocean‐atmosphere model predictions. Agreement between Ar/N2 observations and simulations has improved in comparison to a previous study because of longer time series and the introduction of automated samplers at several of the atmospheric stations, as well as the refinement of the paired ocean‐atmosphere models by inclusion of Ar and N2 as active tracers in the ocean component. Although analytical uncertainties and collection artifacts are likely to be mainly responsible for observed Ar/N2 outliers, air parcel back‐trajectory analysis suggests that some of the variability in Ar/N2 measurements could be due to the low‐altitude history of the air mass collected and, by extension, the local oceanic Ar/N2 signal. Although the simulated climatological seasonal cycle can currently be evaluated with Ar/N2 observations, longer time series and additional improvements in the signal‐to‐noise ratio will be required to test other model predictions such as interannual variability, latitudinal gradients, and the secular increase in atmospheric Ar/N2 expected to result from ocean warming.
A Bayesian analysis of physical habitat changes at tributary confluences in cobble‐bed upland streams of the Acheron River basin, Australia
Authors: Wallis Elizabeth , Nally Ralph Mac , Lake P. S.
Published: November 2008

Tributary confluences are known to affect downstream channel morphology and have the potential to increase downstream habitat heterogeneity. However, few studies have explicitly investigated the effect of tributaries on physical habitat. We used Bayesian modelling to investigate tributary effects on channel morphology, flow velocity, and bed particle size distribution at eight confluences in the Acheron River system in Victoria, Australia, under high‐flow and low‐flow conditions. Consistent tributary effects across sites and flow stages were a localized increase in channel depth at the confluence and a step increase in channel width in the postconfluence channel. Other tributary effects, such as increased or decreased flow velocity, the presence and placement of confluence bed forms (e.g., scours, pools, bars, and avalanche faces), and altered bed particle size distributions, varied between sites and flow conditions. These results provide evidence of changes to the physical habitat at confluences, which may affect stream biota.
Influence of heterogeneity on the interpretation of pumping test data in leaky aquifers
Authors: Copty Nadim K. , Trinchero Paolo , Sanchez‐Vila Xavier , Sarioglu Murat Savas , Findikakis Angelos N.
Published: November 2008

Pumping tests are routinely interpreted from the analysis of drawdown data and their derivatives. These interpretations result in a small number of apparent parameter values which lump the underlying heterogeneous structure of the aquifer. Key questions in such interpretations are (1) what is the physical meaning of those lumped parameters and (2) whether it is possible to infer some information about the spatial variability of the hydraulic parameters. The system analyzed in this paper consists of an aquifer separated from a second recharging aquifer by means of an aquitard. The natural log transforms of the transmissivity, ln T, and the vertical conductance of the aquitard, ln C, are modeled as two independent second‐order stationary spatial random functions (SRFs). The Monte Carlo approach is used to simulate the time‐dependent drawdown at a suite of observation points for different values of the statistical parameters defining the SRFs. Drawdown data at each observation point are independently used to estimate hydraulic parameters using three existing methods: (1) the inflection‐point method, (2) curve‐fitting, and (3) the double inflection‐point method. The resulting estimated parameters are shown to be space dependent and vary with the interpretation method since each method gives different emphasis to different parts of the time‐drawdown data. Moreover, the heterogeneity in the pumped aquifer or the aquitard influences the estimates in distinct manners. Finally, we show that, by combining the parameter estimates obtained from the different analysis procedures, information about the heterogeneity of the leaky aquifer system may be inferred.
High diversity of cultivable heterotrophic bacteria in association with cyanobacterial water blooms
Authors: Berg Katri A , Lyra Christina , Sivonen Kaarina , Paulin Lars , Suomalainen Sini , Tuomi Pirjo , Rapala Jarkko
Published: November 2008

Cyanobacterial mass occurrences (water blooms) cause ecological, economic and health problems worldwide. Still, little is known about heterotrophic bacteria associated with cyanobacteria and the interactions between those organisms. We isolated 460 bacterial strains from more than 40 lakes and rivers (151 samples), Baltic Sea (32 samples) and treated drinking water of seven treatment plants (29 samples). The water bodies and the raw water of the treatment plants were frequently dominated by high numbers of cyanobacteria. Various growth media were used to isolate the strains. Analysis of partial 16S rRNA gene fragments (701–905 bp for 358 strains and 413–497 bp for 102 strains) classified the isolated bacteria as Proteobacteria, Bacteroidetes, Actinobacteria, Firmicutes and Deinococcus-Thermus. Some of these isolates represented possible new bacterial orders, families, genera or species. We isolated various potentially pathogenic bacteria, such as Aeromonas, Vibrio, Acinetobacter and Pseudomonas, that may cause adverse health effects in humans and animals and should be taken into consideration when assessing the risks caused by cyanobacterial blooms. Several strains also inhibited or enhanced the growth of cyanobacteria. Most of such strains had an enhancing effect on the cyanobacterial growth. Other isolates were affiliated with genera such as Sphingomonas or Flavobacterium, which include strains that are capable of degrading cyanobacterial toxins or other recalcitrant and problematic organic compounds. The isolated strains provide a large group of bacteria that could be used in assessing and controlling the harmful effects of cyanobacteria.
Phylogenetic diversity of Acidobacteria in a former agricultural soil
Authors: Kielak Anna , Pijl Agata S , van Veen Johannes A , Kowalchuk George A
Published: November 2008

Although Acidobacteria represent the most abundant bacterial phylum in many soils, knowledge of acidobacterial diversity is still rather incomplete. We, therefore, examined the diversity of 16S rRNA genes affiliated with this phylum in a former arable soil via three independent approaches: (1) screening of a fosmid metagenome library for inserts containing Acidobacteria-like 16S rRNA genes; (2) PCR-cloning using general bacterial primers; and (3) PCR-cloning with acidobacterial-specific primers. Bacterial-specific libraries compared rhizosphere versus bulk soil samples, revealing a higher proportion of acidobacterial sequences in bulk soil libraries (P<0.001). Bacterial libraries recovered the greatest diversity, and sequence examination suggested that sequence mismatches with the Acidobacteria-specific primers limited the coverage of the metagenome library screening and specific library approaches. Together, these results expand knowledge of the distribution and diversity of Acidobacteria in soil environments and highlight important technical considerations in the molecular analysis of Acidobacteria diversity.
Interaction of Salmonella enterica with basil and other salad leaves
Authors: Berger Cedric N , Shaw Robert K , Brown Derek J , Mather Henry , Clare Simon , Dougan Gordon , Pallen Mark J , Frankel Gad
Published: November 2008

Contaminated salad leaves have emerged as important vehicles for the transmission of enteric pathogens to humans. A recent outbreak of Salmonella enterica serovar Senftenberg (S. Senftenberg) in the United Kingdom has been traced to the consumption of contaminated basil. Using the outbreak strain of S. Senftenberg, we found that it binds to basil, lettuce, rocket and spinach leaves showing a pattern of diffuse adhesion. Flagella were seen linking S. Senftenberg to the leaf epidermis, and the deletion of fliC (encoding phase-1 flagella) resulted in a significantly reduced level of adhesion. In contrast, although flagella linking S. enterica serovar Typhimurium to the basil leaf epidermis were widespread, deletion of fliC did not affect leaf attachment levels. These results implicate the role of flagella in Salmonella leaf attachment and suggest that different Salmonella serovars use strain-specific mechanisms to attach to salad leaves.
Identification of the proteome of the midgut of silkworm, Bombyx mori L., by multidimensional liquid chromatography (MDLC) LTQ-Orbitrap MS
Authors: Yao Hui-Peng , Xiang Xing-Wei , Chen Lin , Guo Ai-Qin , He Fang-Qing , Lan Li-Pan , Lu Xing-Meng , Wu Xiao-Feng
Published: November 2008

The midgut is the digestive apparatus of the silkworm and its proteome was studied by using nano-LC (liquid chromatography) electrospray ionization MS/MS (tandem MS). MS data were analysed by using X!Tandem searching software using different parameters and validated by using the Poisson model. A total of 90 proteins were identified and 79 proteins were described for the first time. Among the new proteins, (i) 22 proteins were closely related to the digestive function of the midgut, including 11 proteins of digestive enzymes secreted by the epithelium, eight proteins of intestine wall muscle and mechanical digestion and three proteins of peritrophic membrane that could prevent the epithelium from being mechanically rubbed; (ii) 44 proteins were involved in metabolism of substance and energy; and (iii) 11 proteins were associated with signal transduction, substance transport and cell skeleton.
Dynamic equilibrium engagement of a polyvalent ligand with a single-site receptor
Authors: Mittag Tanja , Orlicky Stephen , Choy Wing-Yiu , Tang Xiaojing , Lin Hong , Sicheri Frank , Kay Lewis E. , Tyers Mike , Forman-Kay Julie D.
Published: November 2008

Intrinsically disordered proteins play critical but often poorly understood roles in mediating protein interactions. The interactions of disordered proteins studied to date typically entail structural stabilization, whether as a global disorder-to-order transition or minimal ordering of short linear motifs. The disordered cyclin-dependent kinase (CDK) inhibitor Sic1 interacts with a single site on its receptor Cdc4 only upon phosphorylation of its multiple dispersed CDK sites. The molecular basis for this multisite-dependent interaction with a single receptor site is not known. By NMR analysis, we show that multiple phosphorylated sites on Sic1 interact with Cdc4 in dynamic equilibrium with only local ordering around each site. Regardless of phosphorylation status, Sic1 exists in an intrinsically disordered state but is surprisingly compact with transient structure. The observation of this unusual binding mode between Sic1 and Cdc4 extends the understanding of protein interactions from predominantly static complexes to include dynamic ensembles of intrinsically disordered states.
Delivery to the Customer's Door: Efficiency, Regulatory Policy, and Integrated Rail-Truck Operations, 1900–1938
Authors: Churella Albert J.
Published: November 2008

During the first third of the twentieth century, U. S. railroad executives offered local collection and delivery trucking operations. Railroad managers claimed, with justification, that these services were necessary to reduce congestion at urban freight terminals, and to increase the operating efficiency. Yet, executives also employed collection and delivery practices to discriminate against shippers and communities, and to draw business away from rival carriers, in violation of the 1887 Interstate Commerce Act, the 1903 Elkins Act, and the Transportation Act of 1920. During the 1920s, as competition from independent truckers became more intense, railroad managers used their inherent advantage in line-haul service to cross-subsidize local delivery services, to the detriment of independent motor carriers—an issue of considerable concern to Interstate Commerce Commission (ICC) commissioners, following the passage of the 1935 Motor Carrier Act. The railroads' emphasis on the productive efficiency associated with local trucking operations conflicted with the allocative efficiency advocated by federal courts and by the ICC. Commissioner Joseph B. Eastman, in particular, emphasized both the potential benefits and the potential dangers associated with coordinated rail-truck service. More broadly, the status of that service, as one of the few forms of transportation that lay beyond the ICC's authority, stemmed from a complex interaction, over several decades, between all three branches of the federal government. By 1938, the ICC commissioners had concluded that the railroads' local delivery operations occupied a nebulous region between rail and truck regulation. While lawful, they did not serve as a model for post-1945 efforts to achieve integrated, multi-modal transportation services.
Human dimensions of Marine Protected Areas
Authors: Charles Anthony , Wilson Lisette
Published: November 2008

Charles, A., and Wilson, L. 2009. Human dimensions of Marine Protected Areas. – ICES Journal of Marine Science, 66: 6–15. Planning, implementing, and managing Marine Protected Areas (MPAs) requires that attention be paid not only to the biological and oceanographic issues that influence the performance of the MPA, but equally to the human dimensions: social, economic, and institutional considerations that can dramatically affect the outcome of MPA implementation. This paper explores ten human dimensions that are basic to the acceptance and ultimate success of MPAs: objectives and attitudes, “entry points” for introducing MPAs, attachment to place, meaningful participation, effective governance, the “people side” of knowledge, the role of rights, concerns about displacement, MPA costs and benefits, and the bigger picture around MPAs. These people-orientated factors and their impact on the success and effectiveness of MPAs are examined in relation to experiences with MPAs globally, and in relation to two Canadian examples specifically, one coastal (Eastport, Newfoundland) and the other offshore (the Gully, Nova Scotia).
A novel pole figure inversion method: specification of theMTEXalgorithm
Authors: Hielscher R. , Schaeben H.
Published: November 2008

A novel algorithm for ODF (orientation density function) estimation from diffraction pole figures is presented which is especially well suited for sharp textures and high-resolution pole figures measured with respect to arbitrarily scattered specimen directions,e.g.by area detectors. The estimated ODF is computed as the solution of a minimization problem which is based on a model of the diffraction counts as a Poisson process. The algorithm applies discretization by radially symmetric functions and fast Fourier techniques to guarantee smooth approximation and high performance. An implementation of the algorithm is freely available as part of the texture analysis softwareMTEX.
Protection of capsaicin against hypoxia–reoxygenation-induced apoptosis of rat hippocampal neurons
Authors: Guo Shi-Yin , Yang Guo-Ping , Jiang De-Jian , Wang Feng , Song Tao , Tan Xing-He , Sun Zhen-Qiu
Published: November 2008

The aim of this study was to investigate the effect of capsaicin on hypoxia–reoxygenation (H/R)-induced apoptosis in primary rat hippocampal neurons. Three hours of hypoxia (1% O2) and subsequent reoxygenation for 24 h significantly increased the apoptotic death of hippocampal neurons, as evidenced by increases in both TUNEL-positive cell number and caspase-3 activity. Pretreatment with capsaicin (3–30 µmol/L) or the caspase-3-specific inhibitor acetyl-DEVD-CHO (100 µmol/L) markedly attenuated H/R-induced apoptosis in hippocampal neurons. Capsaicin also markedly induced the phosphorylation of Akt. The phosphoinositide 3-kinase (PI3K) inhibitor LY294002 (10 µmol/L) prevented any capsaicin-induced survival effect in hippocampal neurons. Intracellular levels of reactive oxygen species (ROS), which were greatly increased after H/R, were significantly inhibited by capsaicin, pyrrolidine dithiocarbamate (PDTC) (50 µmol/L), and LY294002. Taken together, these data suggest that capsaicin protects against H/R-induced apoptosis of hippocampal neurons via the PI3K/Akt-mediated signaling pathway, which is related to the inhibition of oxidative stress and caspase-3 activation.
Genistein inhibits the development of atherosclerosis via inhibiting NF-κB and VCAM-1 expression in LDLR knockout mice
Authors: Wang Juejin , Zhang Rongjian , Xu Youhua , Zhou Hong , Wang Bin , Li Shengnan
Published: November 2008

Diet can be an important factor that influences risks for cardiovascular disease. Genistein (4′,5,7-trihydroxyisoflavone), rich in soy, is one candidate that may benefit the cardiovascular system. Here, we explored the effect of genistein in atherosclerosis (AS) development in an in vivo mouse model. Low-density lipoprotein receptor (LDLR) knockout mice were allocated to control, model, and genistein groups. Our results showed that genistein significantly reduced the formation and development of atherosclerotic plaques ((4.68 ± 1.18) ×106versus (6.65 ± 1.51) ×106µm2, p < 0.05). In the genistein group, compared with the model group, total antioxidant capacity (TAC) level was 85.5 ± 15.6 versus 203.4 ± 32.6 mmol/L (p < 0.01); malondialdehyde (MDA) level was 3.79 ± 0.28 versus 3.06 ± 0.31 mmol/L (p < 0.01), and superoxide dismutase (SOD) activity was 86.1 ± 6.1 versus 139.1 ± 25.1 U/mL (p < 0.01). Therefore, genistein was able to enhance serum antioxidative ability in our mouse model. Genistein had no influence, however, on serum cholesterol and lipid profiles. Genistein also markedly downregulated the expression of nuclear factor (NF)-κB and vascular cell adhesion molecule (VCAM)-1 in aortas of mice (p < 0.05). These observations suggest that genistein may inhibit AS in LDLR−/−mice via enhancing serum antioxidation and downregulating NF-κB and VCAM-1 expression in the aorta.
Rapid cardiovascular effects of dexamethasone in rabbits with meconium-induced acute lung injury
Authors: Mokra Daniela , Tonhajzerova Ingrid , Mokry Juraj , Drgova Anna , Petraskova Maria , Calkovska Andrea , Javorka Kamil
Published: November 2008

Glucocorticoids may improve lung function in newborns with meconium aspiration syndrome (MAS), but information on the acute side effects of glucocorticoids in infants is limited. In this study using a rabbit model of MAS, we addressed the hypothesis that systemic administration of dexamethasone causes acute cardiovascular changes. Adult rabbits were treated with 2 intravenous doses of dexamethasone (0.5 mg/kg each) or saline at 0.5 h and 2.5 h after intratracheal instillation of human meconium or saline. Animals were oxygen-ventilated for 5 h after the first dose of treatment. Blood pressure, heart rate, and short-term heart rate variability (HRV) were analyzed during treatment, for 5 min immediately after each dose, and for the 5 h of the experiment. In the meconium-instilled animals, dexamethasone increased blood pressure, decreased heart rate, increased HRV parameters, and caused cardiac arrhythmia during and immediately after administration. In the saline-instilled animals, the effect of dexamethasone was inconsistent. In these animals, the acute effects of dexamethasone on blood pressure and cardiac rhythm were reversed after 30 min, whereas heart rate continued to decrease and HRV parameters continued to increase for 5 h after the first dose of dexamethasone. These effects were more pronounced in meconium-instilled animals. If systemic glucocorticoids are used in the treatment of MAS, cardiovascular side effects of glucocorticoids should be considered.
Comparative effects ofN-acetyl-l-cysteine and ramipril on arterial hypertension, insulin resistance, and oxidative stress in chronically glucose-fed rats
Authors: El Midaoui Adil , Ismael Mahmoud Ali , Lu Huogen , Fantus I. George , de Champlain Jacques , Couture Réjean
Published: November 2008

Beneficial effects of an antioxidant (N-acetyl-l-cysteine, NAC) and an angiotensin I-converting enzyme (ACE) inhibitor (ramipril) were assessed in a rat model of insulin resistance induced by 10% glucose feeding for 20 weeks. Treatments with NAC (2 g/kg per day) and ramipril (1 mg/kg per day) were initiated at 16 weeks in the drinking fluid. Systolic blood pressure, plasma levels of insulin and glucose, and insulin resistance were significantly higher in rats treated with glucose for 20 weeks. This was associated with a higher production of superoxide anion and NADPH oxidase activity in aorta and liver and with a marked reduction in protein expression of skeletal muscle insulin receptor substrate-1 (IRS-1) in the gastrocnemius muscle. NAC prevented all these alterations. Although ramipril also reversed high blood pressure, it had a lesser effect on insulin resistance (including IRS-1) and blocked superoxide anion production only in aorta. Ramipril, in contrast to NAC, did not reduce NADPH oxidase activity in aorta and liver or plasma levels of 4-hydroxynonenal and malondialdehyde. Results suggest that the inhibition of the oxidative stress in hypertensive and insulin-resistant states contributes to the therapeutic effects of NAC and ramipril. Whereas NAC exerts effective antioxidant activity in multiple tissues, ramipril appears to preferentially target the vasculature.
MHD MODELS AND SYNTHETIC SYNCHROTRON MAPS FOR THE JET OF M87
Authors: GRACIA J. , BOGOVALOV S. V. , TSINGANOS K.
Published: November 2008

We present a self-consistent MHD model for the jet of M87. The model consist of two distinct zones: an inner relativistic outflow, which we identify with the observed jet, and an outer cold disk wind. While the former does not self-collimate efficiently due to its high effective inertia, the latter fulfills all the conditions for efficient collimation by the magneto-centrifugal mechanism. Given the right balance between the effective inertia of the inner flow and the collimation efficiency of the outer disk wind, the relativistic flow is magnetically confined into a well collimated beam for a wide range of parameters and matches the measurements of the opening angle of M87 over several orders of magnitude in spatial extent.

In the second part of this work, we present synthetic synchrotron emission maps for our MHD models. In principle, the two-zone model can reproduce the morphological structure seen in radio observations, as central-peaked profiles across the jet close the the source, limb-bright further down the jet, and a bright knot close to the position of HST-1. However it is difficult to reconcile all features with a single set of parameters.
JET CONFINEMENT BY NONLINEAR MAGNETO-TORSIONAL OSCILLATIONS
Authors: BISNOVATYI-KOGAN G. S.
Published: November 2008

Many quasars and active galactic nuclei are connected with long, thin jets. When observed with high angular resolution, these jets show a structure with bright knots separated by relatively dark regions. We consider magnetic collimation, connected with torsional oscillations of a cylinder with elongated magnetic field, and periodically distributed initial rotation around the cylinder axis. The stabilizing azimuthal magnetic field is created here by torsional oscillations. An approximate, simplified model is developed. The parameters for which jets may be stabilized by torsional oscillations are estimated quantitatively.
MHD SIMULATIONS OF ACCRETION ONTO A MAGNETIZED NEUTRON STAR IN THE "PROPELLER" REGIME
Authors: TOROPINA O. D. , ROMANOVA M. M. , LOVELACE R. V. E.
Published: November 2008

We use axisymmetric magnetohydrodynamic simulations to investigate the spinning-down of magnetars rotating in the propeller regime and moving supersonically through the interstellar medium. The simulations indicate that magnetars spin down rapidly due to this interaction, and faster than for the case of a non-moving star. We discuss this model with respect to soft gamma repeaters (SGRs) and the isolated neutron star candidates.
GRAVITATIONALLY DISTORTED P-CYGNI PROFILES FROM OUTFLOWS NEAR COMPACT OBJECTS
Authors: DORODNITSYN A. V.
Published: November 2008

Spectral line profiles produced in an outflow near a neutron star or a black hole can be strongly influenced by gravitational redshifting and by Doppler shifting due to a global motion of plasma. We consider a scenario in which a resonant absorption in a spectral line takes place in the outflowing plasma within several tens of Schwarzschild radii from a compact object. The main goal of this work is to show that under certain conditions a combination of the gravitational redshifting and Doppler blue/redshifting may produce line profiles which can be considered as "fingerprints" of the gravitational field of the compact object, much as P-Cygni profiles are "fingerprints" of stellar winds.
ABOUT FERMI ACCELERATION AT RELATIVISTIC SHOCKS AND THE SCATTERING ISSUE
Authors: PELLETIER GUY , LEMOINE MARTIN , MARCOWITH ALEXANDRE
Published: November 2008

Difficulties arise in the process of Fermi acceleration at relativistic shocks because they are generically in the superluminal regime and they strongly compress turbulence downstream. Under reasonable conditions usually considered for the turbulent spectrum upstream, cosmic rays do not undergo the scattering that would allow them to make several Fermi cycles. An intense short scale turbulence must be excited in order that the Fermi process can be operative. In this paper, we show the requirement for the turbulence spectrum and give a solution to this issue in the form of the generation of intense compressive waves at short scale upstream. We indicate how the magnetic turbulence compression downstream should not be an obstacle for getting a significant return probability. Thus we conclude that, despite the necessity of some further analysis, the Fermi process at relativistic shock is still promising.
PARTICLE ACCELERATION, MAGNETIC FIELD GENERATION, AND ASSOCIATED EMISSION IN COLLISIONLESS RELATIVISTIC JETS
Authors: NISHIKAWA K.-I. , MIZUNO Y. , FISHMAN G. J. , HARDEE P.
Published: November 2008

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., active galactic nuclei (AGNs), gamma-ray bursts (GRBs), and galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations using injected relativistic electron-ion (electron-positron) jets show that acceleration occurs within the downstream jet. Shock acceleration is an ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., the Buneman instability, other two-streaming instability, and the Weibel instability) created in the shocks are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electrons' transverse deflection behind the jet head. The "jitter" radiation from deflected electrons has different properties to synchrotron radiation which assumes a uniform magnetic field. This jitter radiation may be important to understanding the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.
SELF-SIMILAR SOLUTIONS FOR THE ACCELERATION OF COSMIC RAYS AT A SUPERNOVA SHOCK PROPAGATING INTO A CIRCUMSTELLAR WIND
Authors: BELL A. R.
Published: November 2008

Cosmic ray acceleration may occur at a supernova shock expanding into a circumstellar wind. Self-similar solutions for the cosmic ray distribution are derived firstly when diffusion is isotropic and secondly when the wind sustains a magnetic field in the form of a Parker spiral.
KINETIC SIMULATIONS OF THE CURRENT-DRIVEN INSTABILITY IN COSMIC RAY MODIFIED RELATIVISTIC SHOCKS
Authors: RIQUELME M. A. , SPITKOVSKY A.
Published: November 2008

We study the current-driven instability predicted by Bell (2004) using particle-in-cell simulations. We use one-dimensional simulations to test the dispersion relation and the nonlinear properties of the instability for the case of a relativistic shock front under idealized conditions. We find that if the cosmic rays (CR) are energetic enough to not get deflected by the generated magnetic field, the instability can grow exponentially until the Alfvén velocity of the plasma becomes comparable to the speed of light. We also use one- and two-dimensional simulations to study the effect of the back reaction of the instability on CR. We find that the deflection and filamentation of CR and background plasma play an important role in the saturation of the instability. The current-driven instability is a viable mechanism for the amplification of magnetic fields in both non-relativistic and relativistic shock environments.
OBSERVATIONS OF MICROQUASAR CANDIDATES WITH THE MAGIC TELESCOPE
Authors:   On behalf of the MAGIC Collaboration, RICO J.
Published: November 2008

We report on the results from the observations in very high energy band (VHE, Eγ ≥ 100 GeV ) of the γ-ray binary LS I +61 303 and the black hole X-ray binary (BHXB) Cygnus X-1. LS I +61 303 was recently discovered at VHE by MAGIC1 and here we present the preliminary results from an extensive observation campaign, comprising 112 observation hours covering 4 orbital cycles, aiming at determining the time-dependent features of the VHE emission. Cygnus X-1 was observed for a total of 40 hours during 26 nights, spanning the period between June and November 2006. We report on the results of the searches for steady and variable γ-ray signals from Cygnus X-1, including the first experimental evidence for an intense flare, of duration between 1.5 and 24 hours.
LS I +61 303: MICROQUASAR OR NOT MICROQUASAR?
Authors: ROMERO G. E. , ORELLANA M. , OKAZAKI A. T. , OWOCKI S. P.
Published: November 2008

LS I +61 303 is a puzzling object detected from radio up to very high-energy gamma-rays. Variability has recently been observed in its high-energy emission. The object is a binary system, with a compact object and a Be star as primary. The nature of the secondary and the origin of the gamma-ray emission are not clearly established at present. Recent VLBA radio data have been used to claim that the system is a Be /neutron star colliding wind binary, instead of a microquasar. We review the main views on the nature of LS I +61 303 and present results of 3D SPH simulations that can shed some light on the nature of the system. Our results support an accretion powered source, compatible with a microquasar interpretation.
GAMMA-RAY EMISSION FROM MASSIVE STAR FORMING REGIONS
Authors: ARAUDO A. T. , ROMERO G. E. , BOSCH-RAMON V. , PAREDES J. M.
Published: November 2008

Recent radio observations support a picture for star formation where there is accretion of matter onto a central protostar with the ejection of molecular outflows that can affect the surrounding medium. The impact of a supersonic outflow on the ambient gas can produce a strong shock that could accelerate particles up to relativistic energies. Strong evidence for this has been the detection of nonthermal radio emission coming from the jet termination region of some young massive stars. In the present contribution, we study the possible high-energy emission due to the interaction of relativistic particles, electrons and protons, with the magnetic, photon and matter fields inside a giant molecular cloud. Electrons lose energy via relativistic Bremsstrahlung, synchrotron radiation and inverse Compton interactions, and protons cool mainly through inelastic collisions with atoms in the cloud. We conclude that some massive young stellar objects (YSOs) might be detectable at gamma-rays by next generation instruments, both satellite-borne and ground based.
MULTIWAVELENGTH PROPERTIES OF γ-RAY LOUD BINARY SYSTEMS
Authors: CHERNYAKOVA M. , NERONOV A.
Published: November 2008

Gamma-ray-loud binary systems are a newly identified class of X-ray binaries detected up to TeV energies. Three such systems — PSR B1259–63, LS 5039 and LSI +61 303 — have been firmly detected as persistent or regularly variable TeV γ-ray emitters. The origin of the high-energy activity of these sources is not clear. In this paper we review the multiwavelength properties of these systems and discuss their similarities and peculiarities.
AGN JET AND THERMAL CONDUCTION IN COOLING FLOW CLUSTERS
Authors: BIBI F. ALOUANI , BINNEY J.
Published: November 2008

We consider the effect of thermal conduction along with AGN jet feedback on the intracluster medium (ICM) in cooling flow clusters. A series of three-dimensional AMR hydrodynamic simulations has been carried out to analyze the dynamic of such interaction. We show the limit of applicability of the Spitzer thermal conduction during jet/ICM interaction.
MAGNETIC RECONNECTION AT THE TERMINATION SHOCK OF A STRIPED PULSAR WIND
Authors: PÉTRI JÉRÔME , LYUBARSKY YURI
Published: November 2008

Most of the rotational luminosity of a pulsar is carried away by a relativistic magnetized wind in which the matter energy flux is negligible compared to the Poynting flux. However, observations indicate that most of the Poynting flux is eventually converted into ultrarelativistic particles. The mechanism responsible for this transformation remains poorly understood. Near the equatorial plane of an obliquely rotating pulsar magnetosphere, the magnetic field reverses polarity with the pulsar period, forming a wind with oppositely directed field lines, called a striped wind.

We study the conditions required for magnetic energy release at the termination shock of the striped pulsar wind. Magnetic reconnection is considered via analytical methods and 1D relativistic PIC simulations. An analytical condition on the upstream parameters for partial and full magnetic reconnection is derived from the conservation laws of energy, momentum and particle number density across the relativistic shock. Furthermore, by using a 1D relativistic PIC code, we study in detail the reconnection process at the termination shock for different upstream Lorentz factors and magnetizations, and find good agreement with our analytical criterion. Thus, alternating magnetic fields annihilate easily at relativistic highly magnetized shocks. We apply our criterion for dissipation to deduce bounds on the pair multiplicity, κ, in the pulsar wind.
ACOUSTIC ATTENUATION CHARACTERISTICS OF STRAIGHT-THROUGH PERFORATED TUBE SILENCERS AND RESONATORS
Authors: JI Z. L.
Published: November 2008

The one-dimensional analytical solutions are derived and three-dimensional substructure boundary element approaches are developed to predict and analyze the acoustic attenuation characteristics of straight-through perforated tube silencers and folded resonators without mean flow, as well as to examine the effect of nonplanar waves in the silencers and resonators on the acoustic attenuation performance. Comparisons of transmission loss predictions with the experimental results for prototype straight-through perforated tube silencers demonstrated that the three-dimensional approach is needed for accurate acoustic attenuation performance prediction at higher frequencies, while the simple one-dimensional theory is sufficient at lower frequencies. The BEM is then used to investigate the effects of geometrical parameters on the acoustic attenuation characteristics of straight-through perforated tube silencers and folded resonators in detail.
Transcatheter Valve Repair and Replacement
Authors: Kodali Susheel , Schwartz Allan
Published: November 2008

There is significant interest in developing transcatheter therapy for valvular heart disease (VHD). Numerous devices have been developed for the percutaneous treatment of pulmonary and aortic stenosis as well as mitral regurgitation. Several of these devices have progressed to randomized clinical trials. These ongoing trials for aortic stenosis and mitral regurgitation will provide important insights into the durability of these therapies as well as the results following standard surgical repair. The field of transcatheter valve therapy is rapidly evolving, and this review aims to summarize the current status of the field.
Focal acidosis in the pre-Bötzinger complex area of awake goats induces a mild tachypnea
Authors: Krause K. L. , Forster H. V. , Davis S. E. , Kiner T. , Bonis J. M. , Pan L. G. , Qian B.
Published: November 2008

There are widespread chemosensitive areas in the brain with varying effects on breathing. In the awake goat, microdialyzing (MD) 50% CO2 at multiple sites within the medullary raphe increases pulmonary ventilation (V̇i), blood pressure, heart rate, and metabolic rate (V̇o2) ( 11 ), while MD in the rostral and caudal cerebellar fastigial nucleus has a stimulating and depressant effect, respectively, on these variables ( 17 ). In the anesthetized cat, the pre-Bötzinger complex (preBötzC), a hypothesized respiratory rhythm generator, increases phrenic nerve activity after an acetazolamide-induced acidosis ( 31 , 32 ). To gain insight into the effects of focal acidosis (FA) within the preBötzC during physiological conditions, we tested the hypothesis that FA in the preBötzC during wakefulness would stimulate breathing, by increasing respiratory frequency (f). Microtubules were bilaterally implanted into the preBötzC of 10 goats. Unilateral MD of mock cerebral spinal fluid equilibrated with 6.4% CO2 did not affect V̇i, tidal volume (Vt), or f. Unilateral MD of 25 and 50% CO2 significantly increased V̇i and f by 10% ( P < 0.05, n = 10, 17 trials), but Vt was unaffected. Bilateral MD of 6.4, 25, or 50% CO2 did not significantly affect V̇i, Vt, or f ( P > 0.05, n = 6, 6 trials). MD of 80% CO2 caused a 180% increase in f and severe disruptions in airflow ( n = 2). MD of any level of CO2 did not result in any significant changes in mean arterial blood pressure, heart rate, or V̇o2. Thus the data suggest that the preBötzC area is chemosensitive, but the responses to FA at this site are unique compared with other chemosensitive sites.
Chronic low-frequency rTMS of primary motor cortex diminishes exercise training-induced gains in maximal voluntary force in humans
Authors: Hortobágyi Tibor , Richardson Sarah Pirio , Lomarev Mikhael , Shamim Ejaz , Meunier Sabine , Russman Heike , Dang Nguyet , Hallett Mark
Published: November 2008

Although there is consensus that the central nervous system mediates the increases in maximal voluntary force (maximal voluntary contraction, MVC) produced by resistance exercise, the involvement of the primary motor cortex (M1) in these processes remains controversial. We hypothesized that 1-Hz repetitive transcranial magnetic stimulation (rTMS) of M1 during resistance training would diminish strength gains. Forty subjects were divided equally into five groups. Subjects voluntarily (Vol) abducted the first dorsal interosseus (FDI) (5 bouts × 10 repetitions, 10 sessions, 4 wk) at 70–80% MVC. Another group also exercised but in the 1-min-long interbout rest intervals they received rTMS [Vol+rTMS, 1 Hz, FDI motor area, 300 pulses/session, 120% of the resting motor threshold (rMT)]. The third group also exercised and received sham rTMS (Vol+Sham). The fourth group received only rTMS (rTMS_only). The 37.5% and 33.3% gains in MVC in Vol and Vol+Sham groups, respectively, were greater ( P = 0.001) than the 18.9% gain in Vol+rTMS, 1.9% in rTMS_only, and 2.6% in unexercised control subjects who received no stimulation. Acutely, within sessions 5 and 10, single-pulse TMS revealed that motor-evoked potential size and recruitment curve slopes were reduced in Vol+rTMS and rTMS_only groups and accumulated to chronic reductions by session 10. There were no changes in rMT, maximum compound action potential amplitude (Mmax), and peripherally evoked twitch forces in the trained FDI and the untrained abductor digiti minimi. Although contributions from spinal sources cannot be excluded, the data suggest that M1 may play a role in mediating neural adaptations to strength training.
Voluntary wheel running initially increases adrenal sensitivity to adrenocorticotrophic hormone, which is attenuated with long-term training
Authors: Campbell Jonathan E. , Rakhshani Nasimeh , Fediuc Sergiu , Bruni Silvio , Riddell Michael C.
Published: November 2008

Although exercise is a common and potent activator of the hypothalamic-pituitary adrenal (HPA) axis, the effects of exercise on the acute stress response are not well understood. Here, we investigated the effects of short- (2 wk) and long-term (8 wk) voluntary wheel running on adrenal sensitivity to ACTH stimulation and the acute stress response to restraint in male rats. Diurnal glucocorticoid patterns were measured on days 7 (all groups) and 35 (8-wk groups). Rats were subjected to 20 min of restraint stress on either week 1 or on week 7 of treatment to assess HPA activation. One week later, exogenous ACTH (75 ng/kg) was administered to assess adrenal sensitivity to ACTH. Following this, adrenals were collected and analyzed for key proteins involved in corticosterone (CORT) synthesis. By the end of week 1, exercising (E) animals had twofold higher peak diurnal CORT levels compared with sedentary (S) animals ( P < 0.01). CORT values were not different between groups at week 8. In response to restraint stress at week 2, CORT values in E were approximately threefold greater than in S ( P < 0.05). No difference was found between E and S rats in the response to, or recovery from, restraint at week 8. During the ACTH challenge at week 2, E demonstrated a ∼2.5-fold increase in adrenal sensitivity compared with S, while no difference was found between E and S at week 8. The expression of steroidogenic acute regulatory protein was found to be ∼50% higher in the adrenals in E compared with S at week 2 ( P < 0.05), but no difference existed between groups at week 8. These results show that volitional wheel running initially causes hyperactivation of the HPA axis, due to enhanced adrenal sensitivity to ACTH, but that these alterations in HPA activity are completely restored by 8 wk of training.