311 research outputs found
Structural and functional characterization of (110)-oriented epitaxial La2/3Ca1/3MnO3 electrodes and SrTiO3 tunnel barriers
La2/3Ca1/3MnO3 (LCMO) films have been deposited on (110)-oriented SrTiO3 (STO) substrates. X-ray diffraction and high-resolution electron microscopy reveal that the (110) LCMO films are epitaxial and anisotropically in-plane strained, with higher relaxation along the [1Âż10] direction than along the [001] direction; x-ray absorption spectroscopy data signaled the existence of a single intermediate Mn3+/4+ 3d-state at the film surface. Their magnetic properties are compared to those of (001) LCMO films grown simultaneously on (001) STO substrates It is found that (110) LCMO films present a higher Curie temperature (TC) and a weaker decay of magnetization when approaching TC than their (001) LCMO counterparts. These improved films have been subsequently covered by nanometric STO layers. Conducting atomic-force experiments have shown that STO layers, as thin as 0.8 nm, grown on top of the (110) LCMO electrode, display good insulating properties. We will show that the electric conductance across (110) STO layers, exponentially depending on the barrier thickness, is tunnel-like. The barrier height in STO (110) is found to be similar to that of STO (001). These results show that the (110) LCMO electrodes can be better electrodes than (001) LCMO for magnetic tunnel junctions, and that (110) STO are suitable insulating barriers
Is coffee powder extract a possible functional ingredient useful in food and nutraceutical industries?
The present study aimed to assess the phytochemical content and in vitro bioactivity of ethanolic extracts of Arabica (A) and/or Robusta (R) coffee powder having different geographical origins. For this purpose, total phenols (TPC) and flavonoids (TFC) content as well as a- and b-tocopherol were quantified. The antioxidant activity was assessed by using a multi-target approach in which the radical scavenging potential, the protection from lipid peroxidation, and the involvement of the iron-reducing mechanism were applied. The carbohydrate hydrolyzing enzymesâ (a-amylase and a-glucosidase) inhibitory activities were also assessed. Arabica coffee sample (C2-A) showed the highest TPC, TFC, and a-tocopherol content with values of 63.1 mg chlorogenic acid equivalents (CAE)/g dry powder, 16.2 mg of quercetin (QE) equivalents/g dry powder, and 5.6 mg/100 g dry powder, respectively. Relative Antioxidant Capacity Index (RACI), used to statistically integrate results from 2,2âČ-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing ability power (FRAP), and protection of lipid peroxidation assays, evidenced that sample C4-R derived from Robusta from Guatemala showed the highest antioxidant potential with a value of â0.61. Arabica from Puerto Rico was the most active against a-amylase, whereas the blend Arabica/Robusta sample (C5-A60R40) showed the highest inhibitory activity against a-glucosidase with IC50 values of 120.2 and 134.6 mg/mL, respectively. The results show how the qualitative-quantitative composition of the extracts is strongly associated not only with the variety but also with the geographical origin of the samples
The BaR-SPOrt Experiment
BaR-SPOrt (Balloon-borne Radiometers for Sky Polarisation Observations) is an
experiment to measure the linearly polarized emission of sky patches at 32 and
90 GHz with sub-degree angular resolution. It is equipped with high sensitivity
correlation polarimeters for simultaneous detection of both the U and Q stokes
parameters of the incident radiation. On-axis telescope is used to observe
angular scales where the expected polarization of the Cosmic Microwave
Background (CMBP) peaks. This project shares most of the know-how and
sophisticated technology developed for the SPOrt experiment onboard the
International Space Station. The payload is designed to flight onboard long
duration stratospheric balloons both in the Northern and Southern hemispheres
where low foreground emission sky patches are accessible. Due to the weakness
of the expected CMBP signal (in the range of microK), much care has been spent
to optimize the instrument design with respect to the systematics generation,
observing time efficiency and long term stability. In this contribution we
present the instrument design, and first tests on some components of the 32 GHz
radiometer.Comment: 12 pages, 10 figures, Astronomical Telescopes and Instrumentation
(Polaimetry in Astronomy) Hawaii August 2002 SPIE Meetin
Reducing return of disease activity in patients with relapsing multiple sclerosis transitioned from natalizumab to teriflunomide: 12-month interim results of teriflunomide therapy.
Background: Natalizumab is an effective treatment for relapsing multiple sclerosis. Return of disease activity upon natalizumab discontinuance creates the need for follow-up therapeutic strategies.
Objective: To assess the efficacy of teriflunomide following natalizumab discontinuance in relapsing multiple sclerosis patients.
Methods: Clinically stable relapsing multiple sclerosis patients completing 12 or more consecutive months of natalizumab, testing positive for anti-John Cunningham virus antibody, started teriflunomide 14 mg/day, 28â±â7 days after their final natalizumab infusion. Physical examination, Expanded Disability Status Scale, laboratory assessments, and brain magnetic resonance imaging were performed at screening and multiple follow-up visits.
Results: Fifty-five patients were enrolled in the study. The proportion of patients relapse-free was 0.94, restricted mean time to first gadolinium-enhancing lesion was 10.9 months and time to 3-month sustained disability worsening was 11.8 months. The mean number of new or enlarging T2 lesions per patient at 12 months was 0.42. Exploratory analyses revealed an annualized relapse rate of 0.08, and a proportion of patients with no evidence of disease activity of 0.68. Forty-seven patients (85.5%) reported adverse events, 95% of which were mild to moderate.
Conclusions: Teriflunomide therapy initiated without natalizumab washout resulted in a low rate of return of disease activity. Clinicians may consider this a worthwhile strategy when transitioning clinically stable patients off natalizumab to another therapy.ClinicalTrials.gov Identifier: NCT01970410
The Large-Scale Polarization Explorer (LSPE)
The LSPE is a balloon-borne mission aimed at measuring the polarization of
the Cosmic Microwave Background (CMB) at large angular scales, and in
particular to constrain the curl component of CMB polarization (B-modes)
produced by tensor perturbations generated during cosmic inflation, in the very
early universe. Its primary target is to improve the limit on the ratio of
tensor to scalar perturbations amplitudes down to r = 0.03, at 99.7%
confidence. A second target is to produce wide maps of foreground polarization
generated in our Galaxy by synchrotron emission and interstellar dust emission.
These will be important to map Galactic magnetic fields and to study the
properties of ionized gas and of diffuse interstellar dust in our Galaxy. The
mission is optimized for large angular scales, with coarse angular resolution
(around 1.5 degrees FWHM), and wide sky coverage (25% of the sky). The payload
will fly in a circumpolar long duration balloon mission during the polar night.
Using the Earth as a giant solar shield, the instrument will spin in azimuth,
observing a large fraction of the northern sky. The payload will host two
instruments. An array of coherent polarimeters using cryogenic HEMT amplifiers
will survey the sky at 43 and 90 GHz. An array of bolometric polarimeters,
using large throughput multi-mode bolometers and rotating Half Wave Plates
(HWP), will survey the same sky region in three bands at 95, 145 and 245 GHz.
The wide frequency coverage will allow optimal control of the polarized
foregrounds, with comparable angular resolution at all frequencies.Comment: In press. Copyright 2012 Society of Photo-Optical Instrumentation
Engineers. One print or electronic copy may be made for personal use only.
Systematic reproduction and distribution, duplication of any material in this
paper for a fee or for commercial purposes, or modification of the content of
the paper are prohibite
Angular Power Spectra of the Millimeter Wavelength Background Light from Dusty Star-forming Galaxies with the South Pole Telescope
We use data from the first 100 square-degree field observed by the South Pole
Telescope (SPT) in 2008 to measure the angular power spectrum of temperature
anisotropies contributed by the background of dusty star-forming galaxies
(DSFGs) at millimeter wavelengths. From the auto and cross-correlation of 150
and 220 GHz SPT maps, we significantly detect both Poisson distributed and, for
the first time at millimeter wavelengths, clustered components of power from a
background of DSFGs. The spectral indices between 150 and 220 GHz of the
Poisson and clustered components are found to be 3.86 +- 0.23 and 3.8 +- 1.3
respectively, implying a steep scaling of the dust emissivity index beta ~ 2.
The Poisson and clustered power detected in SPT, BLAST (at 600, 860, and 1200
GHz), and Spitzer (1900 GHz) data can be understood in the context of a simple
model in which all galaxies have the same graybody spectrum with dust
emissivity index of beta = 2 and dust temperature T_d = 34 K. In this model,
half of the 150 GHz background light comes from redshifts greater than 3.2. We
also use the SPT data to place an upper limit on the amplitude of the kinetic
Sunyaev-Zel'dovich power spectrum at l = 3000 of 13 uK^2 at 95% confidence.Comment: 18 pages, 9 figure
SPOrt: an Experiment Aimed at Measuring the Large Scale Cosmic Microwave Background Polarization
SPOrt (Sky Polarization Observatory) is a space experiment to be flown on the
International Space Station during Early Utilization Phase aimed at measuring
the microwave polarized emission with FWHM = 7deg, in the frequency range 22-90
GHz. The Galactic polarized emission can be observed at the lower frequencies
and the polarization of Cosmic Microwave Background (CMB) at 90 GHz, where
contaminants are expected to be less important. The extremely low level of the
CMB Polarization signal (< 1 uK) calls for intrinsically stable radiometers.
The SPOrt instrument is expressly devoted to CMB polarization measurements and
the whole design has been optimized for minimizing instrumental polarization
effects. In this contribution we present the receiver architecture based on
correlation techniques, the analysis showing its intrinsic stability and the
custom hardware development carried out to detect such a low signal.Comment: 9 pages, 5 figures, conference proceeding, to appear in "Polarimetry
in Astronomy", SPIE Symposium on 'Astronomical Telescopes and
Instrumentation', Waikoloa, August 22-28 200
A Study of Cosmic Ray Secondaries Induced by the Mir Space Station Using AMS-01
The Alpha Magnetic Spectrometer (AMS-02) is a high energy particle physics
experiment that will study cosmic rays in the to range and will be installed on the International Space Station
(ISS) for at least 3 years. A first version of AMS-02, AMS-01, flew aboard the
space shuttle \emph{Discovery} from June 2 to June 12, 1998, and collected
cosmic ray triggers. Part of the \emph{Mir} space station was within the
AMS-01 field of view during the four day \emph{Mir} docking phase of this
flight. We have reconstructed an image of this part of the \emph{Mir} space
station using secondary and emissions from primary cosmic rays
interacting with \emph{Mir}. This is the first time this reconstruction was
performed in AMS-01, and it is important for understanding potential
backgrounds during the 3 year AMS-02 mission.Comment: To be submitted to NIM B Added material requested by referee. Minor
stylistic and grammer change
Isotopic Composition of Light Nuclei in Cosmic Rays: Results from AMS-01
The variety of isotopes in cosmic rays allows us to study different aspects
of the processes that cosmic rays undergo between the time they are produced
and the time of their arrival in the heliosphere. In this paper we present
measurements of the isotopic ratios 2H/4He, 3He/4He, 6Li/7Li, 7Be/(9Be+10Be)
and 10B/11B in the range 0.2-1.4 GeV of kinetic energy per nucleon. The
measurements are based on the data collected by the Alpha Magnetic
Spectrometer, AMS-01, during the STS-91 flight in 1998 June.Comment: To appear in ApJ. 12 pages, 11 figures, 6 table
A coherent polarimeter array for the Large Scale Polarization Explorer balloon experiment
We discuss the design and expected performance of STRIP (STRatospheric
Italian Polarimeter), an array of coherent receivers designed to fly on board
the LSPE (Large Scale Polarization Explorer) balloon experiment. The STRIP
focal plane array comprises 49 elements in Q band and 7 elements in W-band
using cryogenic HEMT low noise amplifiers and high performance waveguide
components. In operation, the array will be cooled to 20 K and placed in the
focal plane of a meter telescope providing an angular resolution of
degrees. The LSPE experiment aims at large scale, high sensitivity
measurements of CMB polarization, with multi-frequency deep measurements to
optimize component separation. The STRIP Q-band channel is crucial to
accurately measure and remove the synchrotron polarized component, while the
W-band channel, together with a bolometric channel at the same frequency,
provides a crucial cross-check for systematic effects.Comment: In press on the Proceedings of the SPIE Conference Astronomical
Telescopes + instrumentation 2012, Amsterdam, paper 8446-27
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