A study of the turbulence of the neutral medium in two nearby spiral galaxies

The width of the 21 cm line (HI) emitted by spiral galaxies depends on the physical processes that release energy in the Interstellar Medium (ISM). This quantity is called velocity dispersion (��) and it is proportional first of all to the thermal kinetic energy of the gas. The accepted theoretical picture predicts that the neutral hydrogen component (HI) exists in the ISM in two stable phases: a cold one (CNM, with ��~0.8 km/s) and a warm one (WNM, with ��~8 km/s). However, this is called into question by the observation that the HI gas has usually larger velocity dispersions. This suggests the presence of turbulence in the ISM, although the energy sources remain unknown. In this thesis we want to shed new light on this topic. We have studied the HI line emission of two nearby galaxies: NGC6946 and M101. For the latter we used new deep observations obtained with the Westerbork radio interferometer. Through a gaussian fitting procedure, we produced dispersion maps of the two galaxies. For both of them, we compared the �� values measured in the spiral arms with those in the interarms. In NGC6946 we found that, in both arms and interarms, �� grows with the column density, while we obtained the opposite for M 101. Using a statistical analysis we did not find a significant difference between arm and interarm dispersion distributions. Producing star formation rate density maps (SFRD) of the galaxies, we studied their global and local relations with the HI kinetic energy, as inferred from the measured dispersions. For NGC6946 we obtained a good log-log correlation, in agreement with a simple model of supernova feedback driven turbulence. This shows that in this galaxy turbulent motions are mainly induced by the stellar activity. For M 101 we did not find an analogous correlation, since the gas kinetic energy appears constant with the SFRD. We think that this may indicate that in this galaxy turbulence is driven also by accretion of extragalactic material.

Histamine increases sphingosine kinase-1 expression and activity in the human arterial endothelial cell line EA.hy 926 by a PKC-alpha-dependent mechanism

Sphingosine 1-phosphate (S1P) is a potent mitogenic signal generated from sphingosine by the action of sphingosine kinases (SKs). In this study, we show that in the human arterial endothelial cell line EA.hy 926 histamine induces a time-dependent upregulation of the SK-1 mRNA and protein expression which is followed by increased SK-1 activity. A similar upregulation of SK-1 is also observed with the direct protein kinase C activator 12-O-tetradecanoylphorbol-13-acetate (TPA). In contrast, SK-2 activity is not affected by neither histamine nor TPA. The increased SK-1 protein expression is due to stimulated de novo synthesis since cycloheximide inhibited the delayed SK-1 protein upregulation. Moreover, the increased SK-1 mRNA expression results from an increased promoter activation by histamine and TPA. In mechanistic terms, the transcriptional upregulation of SK-1 is dependent on PKC and the extracellular signal-regulated protein kinase (ERK) cascade since staurosporine and the MEK inhibitor U0126 abolish the TPA-induced SK-1 induction. Furthermore, the histamine effect is abolished by the H1-receptor antagonist diphenhydramine, but not by the H2-receptor antagonist cimetidine. Parallel to the induction of SK-1, histamine and TPA stimulate an increased migration of endothelial cells, which is prevented by depletion of the SK-1 by small interfering RNA (siRNA). To appoint this specific cell response to a specific PKC isoenzyme, siRNA of PKC-alpha, -delta, and -epsilon were used to selectively downregulate the respective isoforms. Interestingly, only depletion of PKC-alpha leads to a complete loss of TPA- and histamine-triggered SK-1 induction and cell migration. In summary, these data show that PKC-alpha activation in endothelial cells by histamine-activated H1-receptors, or by direct PKC activators leads to a sustained upregulation of the SK-1 protein expression and activity which, in turn, is critically involved in the mechanism of endothelial cell migration.

Low-frequency drug-resistant HIV-1 and risk of virological failure to first-line NNRTI-based ART: a multicohort European case-control study using centralized ultrasensitive 454 pyrosequencing.

OBJECTIVES It is still debated if pre-existing minority drug-resistant HIV-1 variants (MVs) affect the virological outcomes of first-line NNRTI-containing ART. METHODS This Europe-wide case-control study included ART-naive subjects infected with drug-susceptible HIV-1 as revealed by population sequencing, who achieved virological suppression on first-line ART including one NNRTI. Cases experienced virological failure and controls were subjects from the same cohort whose viraemia remained suppressed at a matched time since initiation of ART. Blinded, centralized 454 pyrosequencing with parallel bioinformatic analysis in two laboratories was used to identify MVs in the 1%-25% frequency range. ORs of virological failure according to MV detection were estimated by logistic regression. RESULTS Two hundred and sixty samples (76 cases and 184 controls), mostly subtype B (73.5%), were used for the analysis. Identical MVs were detected in the two laboratories. 31.6% of cases and 16.8% of controls harboured pre-existing MVs. Detection of at least one MV versus no MVs was associated with an increased risk of virological failure (OR���=���2.75, 95% CI���=���1.35-5.60, P���=���0.005); similar associations were observed for at least one MV versus no NRTI MVs (OR���=���2.27, 95% CI���=���0.76-6.77, P���=���0.140) and at least one MV versus no NNRTI MVs (OR���=���2.41, 95% CI���=���1.12-5.18, P���=���0.024). A dose-effect relationship between virological failure and mutational load was found. CONCLUSIONS Pre-existing MVs more than double the risk of virological failure to first-line NNRTI-based ART.

Coordinates of multichannel seismic line GeoB05-004

Major plastered drift sequences were imaged using high-resolution multichannel seismics during R/V Meteor cruises M63/1 and M75/3 south of the Mozambique Channel along the continental margin of Mozambique off the Limpopo River. Detailed seismic-stratigraphic analyses enabled the reconstruction of the onset and development of the modern, discontinuous, eddy-dominated Mozambique Current. Major drift sequences can first be identified during the Early Miocene. Consistent with earlier findings, a progressive northward shift of the depocenter indicates that, on a geological timescale, a steady but variable Mozambique Current existed from this time onward. It can furthermore be shown that, during the Early/Middle Miocene, a coast-parallel current was established off the Limpopo River as part of a lee eddy system driven by the Mozambique Current. Modern sedimentation is controlled by the interplay between slope morphology and the lee eddy system, resulting in upwelling of Antarctic Intermediate Water. Drift accumulations at larger depths are related to the reworking of sediment by deep-reaching eddies that migrate southward, forming the Mozambique Current and eventually merging with the Agulhas Current.

The logarithmic spiral, autoisoptic curve

In the Line of Investigation that in the department of ���Technical Drawing��� in the School of Agriculture Engineering of Madrid, we carry out on the study of The Technical Curves and his singularities, we demonstrate an interesting property of the Logarithmic Spiral. The demonstrated property consists of which the logarithmic spiral is a autoisoptic curve, that is to say that if from a point P anyone of the spiral tangent straight lines draw up to the previous arc, these form a constant angle ��. This demonstration is novel and in addition we get to contribute a method to calculate the angle �� given the equation of the spiral.

The variability and interdependence of spider viscid line tensile properties

True stress-true strain curves of naturally spun viscid line fibers retrieved directly from the spiral of orb-webs built by Argiope trifasciata spiders were measured using a novel methodology. This new procedure combines a method for removing the aqueous coating of the fibers and a technique that allows the accurate measurement of their cross sectional area. Comparison of the tensile behaviour of different samples indicates that naturally spun viscid lines show a large variability, comparable to that of other silks, such as major ampullate gland silk and silkworm silk. Nevertheless, application of a statistical analysis allowed identifying two independent parameters that underlie the variability and characterize the observed range of true stress-true strain curves. Combination of this result with previous mechanical and microstructural data suggested the assignment of these two independent effects to the degree of alignment of the protein chains and to the local relative humidity which, in turn, depends on the composition of the viscous coating and on the external environmental conditions.

Convergent and parallel activation of low-conductance potassium channels by calcium and cAMP-dependent protein kinase.

K+ channels, which have been linked to regulation of electrogenic solute transport as well as Ca2+ influx, represent a locus in hepatocytes for the concerted actions of hormones that employ Ca2+ and cAMP as intracellular messengers. Despite considerable study, the single-channel basis for synergistic effects of Ca2+ and cAMP on hepatocellular K+ conductance is not well understood. To address this question, patch-clamp recording techniques were applied to a model liver cell line, HTC hepatoma cells. Increasing the cytosolic Ca2+ concentration ([Ca2+]i) in HTC cells, either by activation of purinergic receptors with ATP or by inhibition of intracellular Ca2+ sequestration with thapsigargin, activated low-conductance (9-pS) K+ channels. Studies with excised membrane patches suggested that these channels were directly activated by Ca2+. Exposure of HTC cells to a permeant cAMP analog, 8-(4-chlorophenylthio)-cAMP, also activated 9-pS K+ channels but did not change [Ca2+]i. In excised membrane patches, cAMP-dependent protein kinase (the downstream effector of cAMP) activated K+ channels with conductance and selectivity identical to those of channels activated by Ca2+. In addition, cAMP-dependent protein kinase activated a distinct K+ channel type (5 pS). These data represent the differential regulation of low-conductance K+ channels by signaling pathways mediated by Ca2+ and cAMP. Moreover, since low-conductance Ca(2+)-activated K+ channels have been identified in a variety of cell types, these findings suggest that differential regulation of K+ channels by hormones with distinct signaling pathways may provide a mechanism for hormonal control of solute transport and Ca(2+)-dependent cellular functions in the liver as well as other nonexcitable tissues.

Oxida����o eletroqu��mica de etanol em temperatura ambiente e intermedi��ria: estudo quantitativo das vias reacionais por espectrometria de massas��on-line

Na primeira parte do trabalho, foram investigados materiais ativos para eletro-oxidar etanol e acetalde��do seletivos para a rota C2 (Carbono 2) e, tamb��m, ativos para eletro-oxidar hidrog��nio molecular, visando a aplica����o em c��lulas a combust��vel de hidrog��nio indireto. Neste tipo de c��lula, um processador de combust��vel externo desidrogena o etanol e os produtos desta rea����o, contendo H2, acetalde��do e, possivelmente, etanol residual, s��o direcionados para alimentar o ��nodo. Neste sentido, o eletrocatalisador an��dico pode ser ativo para a eletro-oxida����o de etanol residual, bem como acetalde��do, mas este deve catalisar a rea����o via C2 com o objetivo de evitar a forma����o de esp��cies que envenenam a superf��cie catal��tica (CO ou CHx), ou seja, a liga����o C-C deve permanecer intacta. Os eletrocatalisadores bimet��licos foram formados por M/Pt/C (onde M = W, Ru ou Sn) e os produtos reacionais foram analisados por DEMS On-line. Os resultados mostraram que Ru/Pt/C e Sn/Pt/C apresentaram maiores taxas de rea����o global, no entanto, eles n��o foram seletivos. Por outro lado, W2/Pt3/C foi mais seletivo para a rota C2, dada a n��o forma����o de CH4 e CO2. Al��m disso, este material tamb��m foi ativo e est��vel para a eletro-oxida����o de H2, mesmo na presen��a de acetalde��do, o que o torna um potencial catalisador para aplica����o no ��nodo de c��lulas a combust��vel de hidrog��nio indireto. Na segunda parte do trabalho, o objetivo foi relacionado com o estudo de eletrocatalisadores seletivos para a rota C1 (Carbono 1). A oxida����o eletroqu��mica do etanol e de seus produtos reacionais foram investigados por DEMS on-line em temperatura ambiente e intermedi��ria (245oC). Para temperatura ambiente, utilizou-se solu����o aquosa de ��cido sulf��rico (H2SO4) e, para temperatura intermedi��ria, utilizou-se ��cido s��lido (CsH2PO4) como eletr��lito. Os eletrocatalisadores investigados foram formados por SnOxRuOx-Pt/C e Pt/C. Em temperatura ambiente, os resultados de polariza����o potenciodin��mica mostraram uma maior atividade eletrocatal��tica para o material SnOxRuOx-Pt/C, com efici��ncia de corrente para forma����o de CO2 de 15,6% contra 15,2% para Pt/C, sob condi����es estagnantes, sem controle por transporte de massa. O stripping de res��duos reacionais, ap��s a eletro-oxida����o de etanol bulk, sob condi����es de fluxo, mostraram o ac��mulo de esp��cies com 1 ��tomo de carbono (CO e CHx) que causam o bloqueio dos s��tios ativos e s��o oxidadas eletroquimicamente somente em mais altos potenciais (ca. 1,0 V). Por outro lado, as curvas de polariza����o a 245oC mostraram maiores valores de efici��ncias de correntes para forma����o de CO2 (45% para Pt/C em ambos potenciais 0,5 V e 0,8 V contra 36% e 50% para SnOxRuOx-Pt/C em 0,5 V e 0,8 V respectivamente) quando comparado com os valores obtidos em temperatura ambiente, mas com atividades similares para SnOxRuOx-Pt/C e Pt/C. Para ambos os eletrocatalisadores, os estudos de espectrometria de massas a 245oC evidenciaram que as rotas eletroqu��micas ocorrem em paralelo com rotas puramente qu��micas, envolvendo cat��lise heterog��nea, de decomposi����o do etanol, produzindo H2 e CO2 como produtos majorit��rios.

Accelerator and detector physics at the Bern medical cyclotron and its beam transport line.

The cyclotron laboratory for radioisotope production and multi-disciplinary research at the Bern University Hospital (Inselspital) is based on an 18-MeV proton accelerator, equipped with a specifically conceived 6-m long external beam line, ending in a separate bunker. This facility allows performing daily positron emission tomography (PET) radioisotope production and research activities running in parallel. Some of the latest developments on accelerator and detector physics are reported. They encompass novel detectors for beam monitoring and studies of low current beams.

Electromagnetic modeling of conformal wideband and multi-band patch antennas by bridging a solid-object modeler with MoM software

The advantages of antennas that can resemble the shape of the body to which they are attached are obvious. However, electromagnetic modeling of such unusually shaped antennas can be difficult. In this paper, the commercially available software SolidWorks(TM) is used for accurately drawing complex shapes in conjunction with the electromagnetic software FEKO(TM) to model the EM behavior of conformal antennas. The application of SolidWorks and custom-written software allows all the required information that forms the analyzed structure to be automatically inserted into FEKO, and gives the user complete control over the antenna being modeled. This approach is illustrated by a number of simulation examples of single, wideband, multi-band planar and curved patch antennas.

Limitations of asymmetric parallel-beam geometry

Bragg diffraction peak profiles and intensities in asymmetric (Omega-2theta) diffraction using a mirror-based parallel-beam geometry were compared with symmetric parallel-beam (theta-2theta) and conventional Bragg - Brentano (theta-2theta) diffraction for a powdered quartz sample and the NIST standard reference material (SRM) 660a (LaB6, lanthanum hexaboride). A comparison of the intensities and line widths (full width at half-maximum, FWHM) of these techniques demonstrated that low incident angles (Omega < 5&DEG;) are preferable for the parallel-beam setup. For higher &UOmega; values, if 2�� < 2Omega, mass absorption reduces the intensities significantly compared with the Bragg - Brentano setup. The diffraction peak shapes for the mirror geometry are more asymmetric and have larger FWHM values than corresponding peaks recorded with a Bragg - Brentano geometry. An asymmetric mirror-based parallel-beam geometry offers some advantages in respect of intensity when compared with symmetric geometries, and hence may be well suited to quantitative studies, such as those involving Rietveld analysis. A trial Rietveld refinement of a 50% quartz - 50% corundum mixture was performed and produced adequate results.

Comments on edge-to-edge matching and the equivalence of the invariant line, Delta g and Moire fringe approaches to the crystallographic features of precipitates

Three apparently distinct and different approaches have been proposed to account for the crystallographic features of diffusion-controlled precipitation. These three models are based on (a) an invariant line in the habit plane, (b) the parallelism of a pair of Deltags that are perpendicular to the habit plane and (c) the parallelism of a pair of Moire fringes that are in turn parallel to the habit plane. The purpose of the present paper is to show that these approaches are in fact absolutely equivalent and that when certain conditions are satisfied they are essentially the same as the recent edge-to-edge matching model put forward by the authors. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Design of compact directive ultra wideband antipodal antenna

In this paper, a novel design procedure for designing a compact UWB antipodal Vivaldi antenna is presented. The antenna operates over the UWB frequency, band from 3.1 to more than 10.6 GHz. Its measured far-field radiation is directive and its peak gain is 10.2 dBi in the specified band. The antenna pulse response shows negligible distortion, indicating that it can be useful in a precision ranging and imaging instrumentation. (c) 2006 Wiley Periodicals, Inc.

A dual band 2.4/5.2GHz antenna including a radial line slot array and a patch

The design of an antenna that combines a radial line slot array and a circular patch to operate as a dual band (2.4/5.2 GHz) antenna at the access point of a WLAN is presented. The design has been accomplished using commercially available Ansoft HFSS and in-house developed software. The designed antenna shows good performance in terms of return losses, radiation pattern and circular polarization in the two, 2.4 and 5.2 GHz, frequency bands. Due to its good electrical performance and a relatively low profile and low developmental cost, it should be found attractive for use as an access point antenna for dual band operation.

Zero-thickness wideband antennas for small radio transceivers

The paper presents investigations into compact zero-thickness wideband antennas capable of operating in many frequency bands within 800-3000MHz. Multi-band operation of these antennas is accomplished by suitable meandering of conducting segments that may be supported by a thin dielectric film. The antennas are capable of operating with a very small ground plane formed by an adjacent conducting surface or a feeding transmission line. Because of the use of flexible materials, these antennas can be conformed to planar or cylindrical structures. Their operation is tested experimentally in stand-alone configurations as well as in the presence of enclosures.