3,551 research outputs found
Wafer-level packaged RF-MEMS switches fabricated in a CMOS fab
Reports on wafer-level packaged RF-MEMS switches fabricated in a commercial CMOS fab. Switch fabrication is based on a metal surface micromachining process. A novel wafer-level packaging scheme is developed, whereby the switches are housed in on-chip sealed cavities using benzocyclobutene (BCB) as the bonding and sealing material. Measurements show that the influence of the wafer-level package on the RF performance can be made very small.\ud
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Is there a difference in physical activity levels in patients before and up to one year after unilateral total hip replacement? A systematic review and meta-analysis
Objective: To determine if there is a difference in physical activity levels before and up to one year after unilateral primary total hip replacement. Data sources: A search was performed on 13th July 2016. Studies were eligible for inclusion if they presented pre-operative and up to one year post-operative measures of physical activity for patients who had undergone unilateral primary total hip replacement. Review methods: Any paper that used a measure of physical activity pre and up to one year post unilateral primary total hip replacement. Data was synthesised using a meta-analysis with 95% confidence intervals (CI), if appropriate. The Critical Appraisal Skills Programme cohort study checklist was used to assess the quality of evidence. Results: From 6024 citations, nine studies were analysed in a meta-analysis and eight studies were analysed qualitatively. The quality of the evidence was ‘low’ to ‘moderate’. There was no statistically significant difference in physical activity pre- to post-total hip replacement when assessed using: movement-related activity (mean difference (MD): -0.08; 95% CI: 1.60, 1.44; I2=0%; n=77), percentage of 24-hours spent walking (MD: -0.21; 95% CI: -1.36, 0.93; I2=12%; n=65), six-minute walk test (MD: -60.85; 95% CI: -122.41, 0.72; I2=84%; n=113) or the cardiopulmonary exercise test (MD: -0.24; 95% CI: -1.36, 0.87; I2=0%;n=76). Conclusion: There is no statistically significant difference in physical activity levels before and up to one year after unilateral primary total hip replacement. However the low to moderate methodological quality of the included papers should be taken into consideration when drawing conclusions
Wide and deep near-UV (360nm) galaxy counts and the extragalactic background light with the Large Binocular Camera
Deep multicolour surveys are the main tool to explore the formation and
evolution of the faint galaxies which are beyond the spectroscopic limit with
the present technology. The photometric properties of these faint galaxies are
usually compared with current renditions of semianalytical models to provide
constraints on the fundamental physical processes involved in galaxy formation
and evolution, namely the mass assembly and the star formation. Galaxy counts
over large sky areas in the near-UV band are important because they are
difficult to obtain given the low efficiency of near-UV instrumentation, even
at 8m class telescopes. A large instrumental field of view helps in minimizing
the biases due to the cosmic variance. We have obtained deep images in the
360nm U band provided by the blue channel of the Large Binocular Camera at the
prime focus of the Large Binocular Telescope. We have derived over an area of
~0.4 sq. deg. the galaxy number counts down to U=27 in the Vega system
(corresponding to U=27.86 in the AB system) at a completeness level of 30%
reaching the faintest current limit for this wavelength and sky area. The shape
of the galaxy counts in the U band can be described by a double power-law, the
bright side being consistent with the shape of shallower surveys of comparable
or greater areas. The slope bends over significantly at U>23.5 ensuring the
convergence of the contribution by star forming galaxies to the EBL in the
near-UV band to a value which is more than 70% of the most recent upper limits
derived for this band. We have jointly compared our near-UV and K band counts
collected from the literature with few selected hierarchical CDM models
emphasizing critical issues in the physical description of the galaxy formation
and evolution.Comment: Accepted for publication in A&A. Uses aa.cls, 9 pages, 4 figures.
Citations update
The VIMOS Public Extragalactic Redshift Survey (VIPERS). Galaxy clustering and redshift-space distortions at z=0.8 in the first data release
We present in this paper the general real- and redshift-space clustering
properties of galaxies as measured in the first data release of the VIPERS
survey. VIPERS is a large redshift survey designed to probe the distant
Universe and its large-scale structure at 0.5 < z < 1.2. We describe in this
analysis the global properties of the sample and discuss the survey
completeness and associated corrections. This sample allows us to measure the
galaxy clustering with an unprecedented accuracy at these redshifts. From the
redshift-space distortions observed in the galaxy clustering pattern we provide
a first measurement of the growth rate of structure at z = 0.8: f\sigma_8 =
0.47 +/- 0.08. This is completely consistent with the predictions of standard
cosmological models based on Einstein gravity, although this measurement alone
does not discriminate between different gravity models.Comment: 19 pages, 19 figures, accepted for publication in A&
A new measurement of the evolving near-infrared galaxy luminosity function out to z~4: a continuing challenge to theoretical models of galaxy formation
We present the most accurate measurement to date of cosmological evolution of
the near-infrared galaxy luminosity function, from the local Universe out to
z~4. The analysis is based on a large and highly complete sample of galaxies
selected from the first data release of the UKIDSS Ultra Deep Survey.
Exploiting a master catalogue of K- and z-band selected galaxies over an area
of 0.7 square degrees, we analyse a sample of ~50,000 galaxies, all with
reliable photometry in 16-bands from the far-ultraviolet to the mid-infrared.
The unique combination of large area and depth provided by the Ultra Deep
Survey allows us to trace the evolution of the K-band luminosity function with
unprecedented accuracy. In particular, via a maximum likelihood analysis we
obtain a simple parameterization for the luminosity function and its
cosmological evolution, including both luminosity and density evolution, which
provides an excellent description of the data from z =0 up to z~4. We find
differential evolution for galaxies dependent on galaxy luminosity, revealing
once again the ``down-sizing behaviour'' of galaxy formation. Finally, we
compare our results with the predictions of the latest theoretical models of
galaxy formation, based both on semi-analytical prescriptions, and on full
hydrodynamical simulations.Comment: 11 pages, 6 figures, submitted to MNRA
Time dependence of the electron and positron components of the cosmic radiation measured by the PAMELA experiment between July 2006 and December 2015
Cosmic-ray electrons and positrons are a unique probe of the propagation of
cosmic rays as well as of the nature and distribution of particle sources in
our Galaxy. Recent measurements of these particles are challenging our basic
understanding of the mechanisms of production, acceleration and propagation of
cosmic rays. Particularly striking are the differences between the low energy
results collected by the space-borne PAMELA and AMS-02 experiments and older
measurements pointing to sign-charge dependence of the solar modulation of
cosmic-ray spectra. The PAMELA experiment has been measuring the time variation
of the positron and electron intensity at Earth from July 2006 to December 2015
covering the period for the minimum of solar cycle 23 (2006-2009) till the
middle of the maximum of solar cycle 24, through the polarity reversal of the
heliospheric magnetic field which took place between 2013 and 2014. The
positron to electron ratio measured in this time period clearly shows a
sign-charge dependence of the solar modulation introduced by particle drifts.
These results provide the first clear and continuous observation of how drift
effects on solar modulation have unfolded with time from solar minimum to solar
maximum and their dependence on the particle rigidity and the cyclic polarity
of the solar magnetic field.Comment: 11 pages, 2 figure
Time dependence of the e^- flux measured by PAMELA during the July 2006 - December 2009 solar minimum
Precision measurements of the electron component in the cosmic radiation
provide important information about the origin and propagation of cosmic rays
in the Galaxy not accessible from the study of the cosmic-ray nuclear
components due to their differing diffusion and energy-loss processes. However,
when measured near Earth, the effects of propagation and modulation of galactic
cosmic rays in the heliosphere, particularly significant for energies up to at
least 30 GeV, must be properly taken into account. In this paper the electron
(e^-) spectra measured by PAMELA down to 70 MeV from July 2006 to December 2009
over six-months time intervals are presented. Fluxes are compared with a
state-of-the-art three-dimensional model of solar modulation that reproduces
the observations remarkably well.Comment: 40 pages, 18 figures, 1 tabl
Search for anisotropies in cosmic-ray positrons detected by the PAMELA experiment
The PAMELA detector was launched on board of the Russian Resurs-DK1 satellite
on June 15, 2006. Data collected during the first four years have been used to
search for large-scale anisotropies in the arrival directions of cosmic-ray
positrons. The PAMELA experiment allows for a full sky investigation, with
sensitivity to global anisotropies in any angular window of the celestial
sphere. Data samples of positrons in the rigidity range 10 GV R
200 GV were analyzed. This article discusses the method and the results of the
search for possible local sources through analysis of anisotropy in positron
data compared to the proton background. The resulting distributions of arrival
directions are found to be isotropic. Starting from the angular power spectrum,
a dipole anisotropy upper limit \delta = 0.166 at 95% C.L. is determined.
Additional search is carried out around the Sun. No evidence of an excess
correlated with that direction was found.Comment: The value of the dipole anisotropy upper limit has been changed. The
method is correct but there was a miscalculation in the relative formul
Time dependence of the proton flux measured by PAMELA during the July 2006 - December 2009 solar minimum
The energy spectra of galactic cosmic rays carry fundamental information
regarding their origin and propagation. These spectra, when measured near
Earth, are significantly affected by the solar magnetic field. A comprehensive
description of the cosmic radiation must therefore include the transport and
modulation of cosmic rays inside the heliosphere. During the end of the last
decade the Sun underwent a peculiarly long quiet phase well suited to study
modulation processes. In this paper we present proton spectra measured from
July 2006 to December 2009 by PAMELA. The large collected statistics of protons
allowed the time variation to be followed on a nearly monthly basis down to 400
MV. Data are compared with a state-of-the-art three-dimensional model of solar
modulation.Comment: 17 pages, 5 figures, 1 table, to appear in Astrophysical Journal.
Corrected two elements of Table
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