1,827 research outputs found
Synthetic Antimicrobial Peptides Exhibit Two Different Binding Mechanisms to the Lipopolysaccharides Isolated from and
Circular dichroism and 1H NMR were used to investigate the interactions of a
series of synthetic antimicrobial peptides (AMPs) with lipopolysaccharides (LPS) isolated from
Pseudomonas aeruginosa and Klebsiella pneumoniae. Previous CD studies with AMPs
containing only three Tic-Oic dipeptide units do not exhibit helical characteristics upon
interacting with small unilamellar vesicles (SUVs) consisting of LPS. Increasing the number of
Tic-Oic dipeptide units to six resulted in five analogues with CD spectra that exhibited helical
characteristics on binding to LPS SUVs. Spectroscopic and in vitro inhibitory data suggest that
there are two possible helical conformations resulting from two different AMP-LPS binding
mechanisms. Mechanism one involves a helical binding conformation where the AMP binds
LPS very strongly and is not efficiently transported across the LPS bilayer resulting in the loss of
inhibitory activity. Mechanism two involves a helical binding conformation where the AMP
binds LPS very loosely and is efficiently transported across the LPS bilayer resulting in an
increase in inhibitory activity. Mechanism three involves a nonhelical binding conformation
where the AMP binds LPS very loosely and is efficiently transported across the LPS bilayer
resulting in an increase in inhibitory activity
Asimadoline and its potential for the treatment of diarrhea-predominant irritable bowel syndrome: a review
Irritable bowel syndrome (IBS) is a multifactorial condition with principal symptoms of pain and altered bowel function. The kappa-opioid agonist asimadoline is being evaluated in Phase III as a potential treatment for IBS. Asimadoline, to date, has shown a good safety profile and the target Phase III population – diarrhea-predominant IBS patients with at least moderate pain – was iteratively determined in a prospective manner from a Phase II dose-ranging study. The clinical data in support of this population are reviewed in this article. Furthermore, the scientific rationale for the use of asimadoline in the treatment of IBS is reviewed. Considering the high patient and societal burdens of IBS, new treatments for IBS represent therapeutic advances
XMM-Newton observation of the relaxed cluster A478: gas and dark matter distribution from 0.01 R_200 to 0.5 R_200
We present an \xmm mosaic observation of the hot ( keV) and nearby
() relaxed cluster of galaxies A478. We derive precise gas density,
gas temperature, gas mass and total mass profiles up to 12\arcmin (about half
of the virial radius ). The gas density profile is highly peaked
towards the center and the surface brightness profile is well fitted by a sum
of three --models. The derived gas density profile is in excellent
agreement, both in shape and in normalization, with the published Chandra
density profile (measured within 5\arcmin of the center). Projection and PSF
effects on the temperature profile determination are thoroughly investigated.
The derived radial temperature structure is as expected for a cluster hosting a
cooling core, with a strong negative gradient at the cluster center. The
temperature rises from keV up to a plateau of keV beyond 2'
(i.e. , Mpc being the virial radius).
From the temperature profile and the density profile and under the hypothesis
of hydrostatic equilibrium, we derived the total mass profile of A478 down to
0.01 and up to 0.5 the virial radius. We tested different dark matter models
against the observed mass profile. The Navarro, Frenk & White
(\cite{navarro97}) model is significantly preferred to other models. It leads
to a total mass of M for a concentration
parameter of . The gas mass fraction slightly increases with
radius. The gas mass fraction at a density contrast of is
\fgas=0.13\pm0.02, consistent with previous results on similar hot and
massive clusters. We confirm the excess of absorption in the direction of
A478.[abridged]Comment: 15 pages, 11 figures, accepted for publication in A&A, corrected
typo
Multiwavelength Mass Comparisons of the z~0.3 CNOC Cluster Sample
Results are presented from a detailed analysis of optical and X-ray
observations of moderate-redshift galaxy clusters from the Canadian Network for
Observational Cosmology (CNOC) subsample of the EMSS. The combination of
extensive optical and deep X-ray observations of these clusters make them ideal
candidates for multiwavelength mass comparison studies. X-ray surface
brightness profiles of 14 clusters with 0.17<z<0.55 are constructed from
Chandra observations and fit to single and double beta-models. Spatially
resolved temperature analysis is performed, indicating that five of the
clusters in this sample exhibit temperature gradients within their inner 60-200
kpc. Integrated spectra extracted within R_2500 provide temperature, abundance,
and luminosity information. Under assumptions of hydrostatic equilibrium and
spherical symmetry, we derive gas and total masses within R_2500 and R_200. We
find an average gas mass fraction within R_200 of 0.136 +/- 0.004, resulting in
Omega_m=0.28 +/- 0.01 (formal error). We also derive dynamical masses for these
clusters to R_200. We find no systematic bias between X-ray and dynamical
methods across the sample, with an average M(dyn)/M(X-ray) = 0.97 +/- 0.05. We
also compare X-ray masses to weak lensing mass estimates of a subset of our
sample, resulting in a weighted average of M(lens)/M(X-ray) of 0.99 +/- 0.07.
We investigate X-ray scaling relationships and find powerlaw slopes which are
slightly steeper than the predictions of self-similar models, with an E(z)^(-1)
Lx-Tx slope of 2.4 +/- 0.2 and an E(z) M_2500-Tx slope of 1.7 +/- 0.1.
Relationships between red-sequence optical richness (B_gc,red) and global
cluster X-ray properties (Tx, Lx and M_2500) are also examined and fitted.Comment: Astrophysical Journal, 48 pages, 11 figures, LaTeX. Added correction
to surface brightness normalization of MS1512.4+3647, corrections to sample
gas mass fractions and calculated value of Omega_m. Figure resolution has
been reduced to comply with astro-ph upload requirement
A comparative study on communication structures of Chinese journals in the social sciences
We argue that the communication structures in the Chinese social sciences
have not yet been sufficiently reformed. Citation patterns among Chinese
domestic journals in three subject areas -- political science and marxism,
library and information science, and economics -- are compared with their
counterparts internationally. Like their colleagues in the natural and life
sciences, Chinese scholars in the social sciences provide fewer references to
journal publications than their international counterparts; like their
international colleagues, social scientists provide fewer references than
natural sciences. The resulting citation networks, therefore, are sparse.
Nevertheless, the citation structures clearly suggest that the Chinese social
sciences are far less specialized in terms of disciplinary delineations than
their international counterparts. Marxism studies are more established than
political science in China. In terms of the impact of the Chinese political
system on academic fields, disciplines closely related to the political system
are less specialized than those weakly related. In the discussion section, we
explore reasons that may cause the current stagnation and provide policy
recommendations
Explaining the Success of the Asian NICs: incentives and technology
SUMMARY This article sets out the essential links in the neoclassical interpretation of Asian NIC performance, as exemplified in the work of Little and Balassa. It considers some theoretical weaknesses in the neoclassical argument; and summarises evidence about South Korea which questions the argument on empirical grounds. To understand the sources of economic growth in the Asian NICs the theoretical framework must be expanded to include not only prices but also the process of innovation, especially in production engineering. RESUMEN Explicación del éxito de los paÃses asiáticos no industrializados: incentivos y tecnologÃa Este articulo expone los vÃnculos esenciales existentes en la interpretación neoclásica de la trayectoria de los paÃses asiáticos no industrializados, según aparecen ejemplificades en el trabajo de Little y Balassa. Considera algunas debilidades de los planteamientos neoclásicos y detalla hechos de Corea del Sur. cuestionando aquellos sobre bases empÃricas. Para comprender la fuentes del crecimiento económico de los paÃses asiáticos no industrializados, es necesario ampliar el marco teórico de modo de incluir no sólo los precios, sino también la innovación, especialmente en los que se refiere a ingenierÃa de producción. RESUMES La clé du succès du NICs en Asie: les motifs et la technologie Cet article établit les liens essentiels dans l'interprétation néoclassique de l'accomplissement du NIC en Asie, vu à travers le travail de Little et Balassa. Il considère certaines faiblesses théoriques dans l'argument neo?classique; et résume l'évidence au sujet de la Corée du Sud qui met en question l'argument à un niveau empirique. Afin de comprendre les sources de croissance économique dans le NIC en Asie la structure théorique doit être développé afin d'inclure non seulement les prix mais aussi le procédé d'innovation, surtout dans la production de la construction mécanique
Product assurance technology for procuring reliable, radiation-hard, custom LSI/VLSI electronics
Advanced measurement methods using microelectronic test chips are described. These chips are intended to be used in acquiring the data needed to qualify Application Specific Integrated Circuits (ASIC's) for space use. Efforts were focused on developing the technology for obtaining custom IC's from CMOS/bulk silicon foundries. A series of test chips were developed: a parametric test strip, a fault chip, a set of reliability chips, and the CRRES (Combined Release and Radiation Effects Satellite) chip, a test circuit for monitoring space radiation effects. The technical accomplishments of the effort include: (1) development of a fault chip that contains a set of test structures used to evaluate the density of various process-induced defects; (2) development of new test structures and testing techniques for measuring gate-oxide capacitance, gate-overlap capacitance, and propagation delay; (3) development of a set of reliability chips that are used to evaluate failure mechanisms in CMOS/bulk: interconnect and contact electromigration and time-dependent dielectric breakdown; (4) development of MOSFET parameter extraction procedures for evaluating subthreshold characteristics; (5) evaluation of test chips and test strips on the second CRRES wafer run; (6) two dedicated fabrication runs for the CRRES chip flight parts; and (7) publication of two papers: one on the split-cross bridge resistor and another on asymmetrical SRAM (static random access memory) cells for single-event upset analysis
A direct limit on the turbulent velocity of the intracluster medium in the core of Abell 1835 from XMM-Newton
We examine deep XMM-Newton Reflection Grating Spectrometer (RGS) observations
of the X-ray luminous galaxy cluster A1835. For the first time in a galaxy
cluster we place direct limits on turbulent broadening of the emission lines.
This is possible because the coolest X-ray emitting gas in the cluster, which
is responsible for the lines, occupies a small region within the core. The most
conservative determination of the 90 per cent upper limit on line-of-sight,
non-thermal, velocity broadening is 274 km/s, measured from the emission lines
originating within 30 kpc radius. The ratio of turbulent to thermal energy
density in the core is therefore less than 13 per cent. There are no emission
lines in the spectrum showing evidence for gas below ~3.5 keV. We examine the
quantity of gas as a function of temperature and place a limit of 140 Msun/yr
(90 per cent) for gas cooling radiatively below 3.85 keV.Comment: 5 pages, accepted by MNRAS, includes minor change suggested by
refere
Adaptive optics near infrared integral field spectroscopy of NGC 2992
NGC 2992 is an intermediate Seyfert 1 galaxy showing outflows on kilo parsec
scales which might be due either to AGN or starburst activity. We therefore aim
at investigating its central region for a putative starburst in the past and
its connection to the AGN and the outflows. Observations were performed with
the adaptive optics near infrared integral field spectrograph SINFONI on the
VLT, complemented by longslit observations with ISAAC on the VLT, as well as N-
and Q-band data from the Spitzer archive. The spatial and spectral resolutions
of the SINFONI data are 50 pc and 83 km/s, respectively. The field of view of
3" x 3" corresponds to 450 pc x 450 pc. Br_gamma equivalent width and line
fluxes from PAHs were compared to stellar population models to constrain the
age of the putative recent star formation. A simple geometric model of two
mutually inclined disks and an additional cone to describe an outflow was
developed to explain the observed complex velocity field in H_2 1-0S(1). The
morphologies of the Br_gamma and the stellar continuum are different suggesting
that at least part of the Br_gamma emission comes from the AGN. This is
confirmed by PAH emission lines at 6.2 micron and 11.2 micron and the strength
of the silicon absorption feature at 9.7 micron, which point to dominant AGN
activity with a relatively minor starburst contribution. We find a starburst
age of 40 Myr - 50 Myr from Br_gamma line diagnostics and the radio continuum;
ongoing star formation can be excluded. Both the energetics and the timescales
indicate that the outflows are driven by the AGN rather than the starburst. The
complex velocity field observed in H_2 1-0S(1) in the central 450 pc can be
explained by the superposition of the galaxy rotation and an outflow.Comment: 10 pages, 8 figures, accepted for publication in A&
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