7,619 research outputs found
A prospective observational study of mycophenolate mofetil treatment in progressive diffuse cutaneous systemic sclerosis of recent onset.
OBJECTIVE: A prospective observational study of mycophenolate mofetil (MMF) treatment in patients with diffuse progressive cutaneous systemic sclerosis (SSc) of recent onset.
METHODS: Twenty-five previously untreated consecutive patients with recent-onset (\u3c 24 mo) diffuse progressive cutaneous SSc received MMF as the only disease-modifying therapy. Modified Rodnan skin score (mRSS) and affected body surface area (BSA) were compared from initiation of MMF to study end. Pulmonary function tests performed at the same institution before therapy and at study end were available in 15 patients. Histopathology and real-time PCR assessment of fibrosis-related gene expression were performed before and after treatment in skin biopsies from 3 patients.
RESULTS: At 18.2 ± 8.73 months of MMF therapy (median 2000 mg/day) the mRSS decreased from 24.56 ± 8.62 to 14.52 ± 10.9 (p = 0.0004) and the affected BSA from 36% ± 16% to 14% ± 13.3% (p = 0.00001). Pulmonary function tests remained stable from initiation of MMF to the end of the study. Skin histopathology showed a remarkable reduction in accumulation of fibrotic tissue. Real-time PCR of skin biopsies demonstrated a marked decrease in expression of fibrosis-related genes.
CONCLUSION: Patients with diffuse progressive cutaneous SSc of recent onset treated with MMF experienced marked improvement in skin involvement and stabilization of pulmonary function. Skin biopsies from 3 patients demonstrated histopathological improvement and decreased expression of fibrosis-related genes
Influence of MWCNT/surfactant dispersions on the mechanical properties of Portland cement pastes
This work studies the reinforcing effect of Multi Walled Carbon Nanotubes (MWCNT) on cement pastes. A 0.35% solid concentration of MWCNT in powder was dispersed in deionized water with sodium dodecyl sulfate (cationic surfactant), cetylpyridinium chloride (anionic surfactant) and triton X-100 (amphoteric surfactant) using an ultrasonic tip processor. Three concentrations of each surfactant (1mM, 10mM and 100mM) were tested, and all samples were sonicated until an adequate dispersion degree was obtained. Cement pastes with additions of carbon nanotubes of 0.15% by mass of cement were produced in two steps; first the dispersions of MWCNT were combined with the mixing water using an ultrasonic tip processor to guarantee homogeneity, and then cement was added and mixed until a homogeneous paste was obtained. Direct tensile strength, apparent density and open porosity of the pastes were measured after 7 days of curing. It was found that the MWCNT/surfactants dispersions decrease the mechanical properties of the cement based matrix due to an increased porosity caused by the presence of surfactants. © Published under licence by IOP Publishing Ltd
Lattice Boltzmann scheme for relativistic fluids
A Lattice Boltzmann formulation for relativistic fluids is presented and
numerically verified through quantitative comparison with recent hydrodynamic
simulations of relativistic shock-wave propagation in viscous quark-gluon
plasmas. This formulation opens up the possibility of exporting the main
advantages of Lattice Boltzmann methods to the relativistic context, which
seems particularly useful for the simulation of relativistic fluids in
complicated geometries.Comment: Submitted to PR
Molecular Electroporation and the Transduction of Oligoarginines
Certain short polycations, such as TAT and polyarginine, rapidly pass through
the plasma membranes of mammalian cells by an unknown mechanism called
transduction as well as by endocytosis and macropinocytosis. These
cell-penetrating peptides (CPPs) promise to be medically useful when fused to
biologically active peptides. I offer a simple model in which one or more CPPs
and the phosphatidylserines of the inner leaflet form a kind of capacitor with
a voltage in excess of 180 mV, high enough to create a molecular electropore.
The model is consistent with an empirical upper limit on the cargo peptide of
40--60 amino acids and with experimental data on how the transduction of a
polyarginine-fluorophore into mouse C2C12 myoblasts depends on the number of
arginines in the CPP and on the CPP concentration. The model makes three
testable predictions.Comment: 15 pages, 5 figure
Shedding light on the formation of the pre-biotic molecule formamide with ASAI
Formamide (NH2CHO) has been proposed as a pre-biotic precursor with a key
role in the emergence of life on Earth. While this molecule has been observed
in space, most of its detections correspond to high-mass star-forming regions.
Motivated by this lack of investigation in the low-mass regime, we searched for
formamide, as well as isocyanic acid (HNCO), in 10 low- and intermediate-mass
pre-stellar and protostellar objects. The present work is part of the IRAM
Large Programme ASAI (Astrochemical Surveys At IRAM), which makes use of
unbiased broadband spectral surveys at millimetre wavelengths. We detected HNCO
in all the sources and NH2CHO in five of them. We derived their abundances and
analysed them together with those reported in the literature for high-mass
sources. For those sources with formamide detection, we found a tight and
almost linear correlation between HNCO and NH2CHO abundances, with their ratio
being roughly constant -between 3 and 10- across 6 orders of magnitude in
luminosity. This suggests the two species are chemically related. The sources
without formamide detection, which are also the coldest and devoid of hot
corinos, fall well off the correlation, displaying a much larger amount of HNCO
relative to NH2CHO. Our results suggest that, while HNCO can be formed in the
gas phase during the cold stages of star formation, NH2CHO forms most
efficiently on the mantles of dust grains at these temperatures, where it
remains frozen until the temperature rises enough to sublimate the icy grain
mantles. We propose hydrogenation of HNCO as a likely formation route leading
to NH2CHO.Comment: 26 pages, 9 figures. Accepted by Monthly Notices of the Royal
Astronomical Societ
Sulfur, Chlorine, & Argon Abundances in Planetary Nebulae. I: Observations and Abundances in a Northern Sample
This paper is the first of a series specifically studying the abundances of
sulfur, chlorine, and argon in Type II planetary nebulae (PNe) in the Galactic
disk. Ratios of S/O, Cl/O, and Ar/O constitute important tests of differential
nucleosynthesis of these elements and serve as strict constraints on massive
star yield predictions. We present new ground-based optical spectra extending
from 3600-9600 Angstroms for a sample of 19 Type II northern PNe. This range
includes the strong near infrared lines of [S III] 9069,9532, which allows us
to test extensively their effectiveness as sulfur abundance indicators. We also
introduce a new, model-tested ionization correction factor for sulfur. For the
present sample, we find average values of S/O=1.2E-2(+/- 0.71E-2),
Cl/O=3.3E-4(+/- 1.6E-4), and Ar/O=5.0E-3(+/- 1.9E-3).Comment: 44 pages, 6 figures. Accepted for publication in the Astrophysical
Journa
Surface shape resonances in lamellar metallic gratings
The specular reflectivity of lamellar gratings of gold with grooves 0.5
microns wide separated by a distance of 3.5 microns was measured on the 2000
cm - 7000 cm spectral range for p-polarized light. For the first
time, experimental evidence of the excitation of electromagnetic surface shape
resonances for optical frequencies is given. In these resonances the electric
field is highly localized inside the grooves and is almost zero in all other
regions. For grooves of depth equal to 0.6 microns, we have analyzed one of
these modes whose wavelength (3.3 microns) is much greater than the lateral
dimension of the grooves.Comment: 4 pages (LaTex), 5 postscript figures, to be published in Physical
Review Letter
Active Vibration Control for Helicopter Interior Noise Reduction Using Power Minimization
This report describes work performed by United Technologies Research Center (UTRC) for NASA Langley Research Center (LaRC) under Contract NNL11AA06C. The objective of this program is to develop technology to reduce helicopter interior noise resulting from multiple gear meshing frequencies. A novel active vibration control approach called Minimum Actuation Power (MAP) is developed. MAP is an optimal control strategy that minimizes the total input power into a structure by monitoring and varying the input power of controlling sources. MAP control was implemented without explicit knowledge of the phasing and magnitude of the excitation sources by driving the real part of the input power from the controlling sources to zero. It is shown that this occurs when the total mechanical input power from the excitation and controlling sources is a minimum. MAP theory is developed for multiple excitation sources with arbitrary relative phasing for single or multiple discrete frequencies and controlled by a single or multiple controlling sources. Simulations and experimental results demonstrate the feasibility of MAP for structural vibration reduction of a realistic rotorcraft interior structure. MAP control resulted in significant average global vibration reduction of a single frequency and multiple frequency excitations with one controlling actuator. Simulations also demonstrate the potential effectiveness of the observed vibration reductions on interior radiated noise
The secondary minimum in YY Her: Evidence for a tidally distorted giant
We present and analyze quiescent UBVRI light curves of the classical
symbiotic binary YY Her. We show that the secondary minimum, which is clearly
visible only in the quiescent VRI light curves, is due to ellipsoidal
variability of the red giant component. Our simple light curve analysis, by
fitting of the Fourier cosine series, resulted in a self-consistent
phenomenological model of YY Her, in which the periodic changes can be
described by a combination of the ellipsoidal changes and a sinusoidal changes
of the nebular continuum and line emission.Comment: 5 pages, 2 figures, to appear in Astronomy & Astrophysic
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