486 research outputs found
Risk factors for syngeneic graft-versus-host disease in adult hematopoietic stem cell transplants
The molecular basis of phosphite and hypophosphite recognition by ABC-transporters
Inorganic phosphate is the major bioavailable form of the essential nutrient phosphorus. However, the concentration of phosphate in most natural habitats is low enough to limit microbial growth. Under phosphate-depleted conditions some bacteria utilise phosphite and hypophosphite as alternative sources of phosphorus, but the molecular basis of reduced phosphorus acquisition from the environment is not fully understood. Here, we present crystal structures and ligand binding affinities of periplasmic binding proteins from bacterial phosphite and hypophosphite ATP-binding cassette transporters. We reveal that phosphite and hypophosphite specificity results from a combination of steric selection and the presence of a P-H…π interaction between the ligand and a conserved aromatic residue in the ligand-binding pocket. The characterisation of high affinity and specific transporters has implications for the marine phosphorus redox cycle, and might aid the use of phosphite as an alternative phosphorus source in biotechnological, industrial and agricultural applications
Isoscalar dipole strength in ^{208}_{82}Pb_{126}: the spurious mode and the strength in the continuum
Isoscalar dipole (compression) mode is studied first using schematic
harmonic-oscillator model and, then, the self-consistent Hartree-Fock (HF) and
random phase approximation (RPA) solved in coordinate space. Taking ^{208}Pb
and the SkM* interaction as a numerical example, the spurious component and the
strength in the continuum are carefully examined using the sum rules. It is
pointed out that in the continuum calculation one has to use an extremely fine
radial mesh in HF and RPA in order to separate, with good accuracy, the
spurious component from intrinsic excitations.Comment: 19 pages, 2 figure
Modified Hagedorn formula including temperature fluctuation - Estimation of temperatures at RHIC experiments -
We have systematically estimated the possible temperatures obtained from an
analysis of recent data on distributions observed at RHIC experiments.
Using the fact that observed distributions cannot be described by the
original Hagedorn formula in the whole range of transverse momenta (in
particular above 6 GeV/c), we propose a modified Hagedorn formula including
temperature fluctuation. We show that by using it we can fit
distributions in the whole range and can estimate consistently the relevant
temperatures, including their fluctuations.Comment: Some misprints corrected, references updated. To be published in Eur.
Phys. J. C (2006
Holography, Pade Approximants and Deconstruction
We investigate the relation between holographic calculations in 5D and the
Migdal approach to correlation functions in large N theories. The latter
employs Pade approximation to extrapolate short distance correlation functions
to large distances. We make the Migdal/5D relation more precise by quantifying
the correspondence between Pade approximation and the background and boundary
conditions in 5D. We also establish a connection between the Migdal approach
and the models of deconstructed dimensions.Comment: 28 page
Nuclear Modification Factor for Charged Pions and Protons at Forward Rapidity in Central Au+Au Collisions at 200 GeV
We present spectra of charged pions and protons in 0-10% central Au+Au
collisions at GeV at mid-rapidity () and forward
pseudorapidity () measured with the BRAHMS experiment at RHIC. The
spectra are compared to spectra from p+p collisions at the same energy scaled
by the number of binary collisions. The resulting nuclear modification factors
for central Au+Au collisions at both and exhibit suppression
for charged pions but not for (anti-)protons at intermediate . The
ratios have been measured up to GeV/ at the two
rapidities and the results indicate that a significant fraction of the charged
hadrons produced at intermediate range are (anti-)protons at both
mid-rapidity and
Anti-inflammatory nutrition with high protein attenuates cardiac and skeletal muscle alterations in a pulmonary arterial hypertension model
Pulmonary arterial hypertension (PAH) is characterized by remodelling of the pulmonary arteries and right ventricle (RV), which leads to functional decline of cardiac and skeletal muscle. This study investigated the effects of a multi-targeted nutritional intervention with extra protein, leucine, fish oil and oligosaccharides on cardiac and skeletal muscle in PAH. PAH was induced in female C57BL/6 mice by weekly injections of monocrotaline (MCT) for 8 weeks. Control diet (sham and MCT group) and isocaloric nutritional intervention (MCT + NI) were administered. Compared to sham, MCT mice increased heart weight by 7%, RV thickness by 13% and fibrosis by 60% (all p < 0.05) and these were attenuated in MCT + NI mice. Microarray and qRT-PCR analysis of RV confirmed effects on fibrotic pathways. Skeletal muscle fiber atrophy was induced (P < 0.05) by 22% in MCT compared to sham mice, but prevented in MCT + NI group. Our findings show that a multi-targeted nutritional intervention attenuated detrimental alterations to both cardiac and skeletal muscle in a mouse model of PAH, which provides directions for future therapeutic strategies targeting functional decline of both tissues
Forward and midrapidity like-particle ratios from p+p collisions at sqrt(s)=200 GeV
We present a measurement of pi-\pi+, K-/K+ and pbar/p from p+p collisions at
sqrt(s) = 20 0GeV over the rapidity range 0<y<3.4. For pT < 2.0 GeV/c we see no
significant transverse momentum dependence of the ratios. All three ratios are
independent of rapidity for y ~< 1.5 and then steadily decline from y ~ 1.5 to
y ~ 3. The pi-\pi+ ratio is below unity for y > 2.0. The pbar/p ratio is very
similar for p+p and 20% central Au+Au collisions at all rapidities. In the
fragmentation region the three ratios seem to be independent of beam energy
when viewed from the rest frame of one of the protons. Theoretical models based
on quark-diquark breaking mechanisms overestimate the pbar/p ratio up to y ~<
3. Including additional mechanisms for baryon number transport such as baryon
junctions leads to a better description of the data.Comment: 15 pages, 4 figures, uses elsart.sty. Changes to references and
discussion based on referee comments, resubmitted to Phys. Lett.
Limiting temperature from a parton gas with power-law tailed distribution
We combine Tsallis distributed massless partons to an effective thermal
prehadron spectrum by folding. A limiting temperature and a mass spectrum
combined of three exponentials emerge from this procedure. Meson and baryon
resonance spectra have different polynomial prefactors.Comment: 4 pages, 2 figures, revtex4 style, v2 more reference
The application of a novel fluidised photo reactor under UV-Visible and natural solar irradiation in the photocatalytic generation of hydrogen.
With advancements in the development of visible light responsive catalysts for H2 production frequently being reported, photocatalytic water splitting has become an attractive method as a potential 'solar fuel generator'. The development of novel photo reactors which can enhance the potential of such catalyst, however, is rarely reported. This is particularly important as many reactor configurations are mass transport limited, which in turn limits the efficiency of more effective photocatalysts in larger scale applications. This paper describes the performance of a novel fluidised photo reactor for the production of H2 over two catalysts under UV-Visible light and natural solar illumination. Catalysts Pt-C3N4 and NaTaO3·La were dispersed in the reactor and the rate of H2 was determined by GC-TCD analysis of the gas headspace. The unit was an annular reactor constructed from stainless steel 316 and quartz glass with a propeller located in the base to control fluidisation of powder catalysts. Reactor properties such as propeller rotational speed were found to enhance the photo activity of the system through the elimination of mass transport limitations and increasing light penetration. The optimum conditions for H2 evolution were found to be a propeller rotational speed of 1035rpm and 144W of UV-Visible irradiation, which produced a rate of 89μmol h-1 g-1 over Pt-C3N4. Solar irradiation was provided by the George Ellery Hale Solar Telescope, located at the California Institute of Technology
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