15,982 research outputs found
UEFI BIOS Accessibility for the Visually Impaired
People with some kind of disability face a high level of difficulty for
everyday tasks because, in many cases, accessibility was not considered
necessary when the task or process was designed. An example of this scenario is
a computer's BIOS configuration screens, which do not consider the specific
needs, such as screen readers, of visually impaired people. This paper proposes
the idea that it is possible to make the pre-operating system environment
accessible to visually impaired people. We report our work-in-progress in
creating a screen reader prototype, accessing audio cards compatible with the
High Definition Audio specification in systems running UEFI compliant firmware.Comment: 6 page
HerMES: Lyman Break Galaxies Individually Detected at 0.7 ā¤ z ā¤ 2.0 in GOODS-N with Herschel/SPIRE
As part of the Herschel Multi-tiered Extragalactic Survey we have investigated the rest-frame far-infrared (FIR) properties of a sample of more than 4800 Lyman break galaxies (LBGs) in the Great Observatories Origins Deep Survey North field. Most LBGs are not detected individually, but we do detect a sub-sample of 12 objects at 0.7 2.5. The UV-to-FIR spectral energy distributions of the objects detected in the rest-frame FIR are investigated using the code CIGALE to estimate physical parameters. We find that LBGs detected by SPIRE are high-mass, luminous infrared galaxies. It appears that LBGs are located in a triangle-shaped region in the A_(FUV) versus log L_(FUV) = 0 diagram limited by A_(FUV) = 0 at the bottom and by a diagonal following the temporal evolution of the most massive galaxies from the bottom right to the top left of the diagram. This upper envelop can be used as upper limits for the UV dust attenuation as a function of L_(FUV). The limits of this region are well explained using a closed-box model, where the chemical evolution of galaxies produces metals, which in turn lead to higher dust attenuation when the galaxies age
Improved Constraints on Cosmic Microwave Background Secondary Anisotropies from the Complete 2008 South Pole Telescope Data
We report measurements of the cosmic microwave background (CMB) power spectrum from the complete 2008 South Pole Telescope (SPT) data set. We analyze twice as much data as the first SPT power spectrum analysis, using an improved cosmological parameter estimator which fits multi-frequency models to the SPT 150 and 220 GHz bandpowers. We find an excellent fit to the measured bandpowers with a model that includes lensed primary CMB anisotropy, secondary thermal (tSZ) and kinetic (kSZ) Sunyaev-Zel'dovich anisotropies, unclustered synchrotron point sources, and clustered dusty point sources. In addition to measuring the power spectrum of dusty galaxies at high signal-to-noise, the data primarily constrain a linear combination of the kSZ and tSZ anisotropy contributions at 150 GHz and ā = 3000: D^(tSZ) ^(3000) + 0.5 D_(kSZ)^(3000) = 4.5 Ā± 1.0 Ī¼K^2. The 95% confidence upper limits on secondary anisotropy power are D ^(tSZ)_(3000) < 5.3 Ī¼K^2 and D^(kSZ)_(3000) < 6.5 Ī¼K^2. We also consider the potential correlation of dusty and tSZ sources and find it incapable of relaxing the tSZ upper limit. These results increase the significance of the lower than expected tSZ amplitude previously determined from SPT power spectrum measurements. We find that models including non-thermal pressure support in groups and clusters predict tSZ power in better agreement with the SPT data. Combining the tSZ power measurement with primary CMB data halves the statistical uncertainty on Ļ8. However, the preferred value of Ļ8 varies significantly between tSZ models. Improved constraints on cosmological parameters from tSZ power spectrum measurements require continued progress in the modeling of the tSZ power
A Measurement of the Damping Tail of the Cosmic Microwave Background Power Spectrum with the South Pole Telescope
We present a measurement of the angular power spectrum of the cosmic microwave background (CMB) using data from the South Pole Telescope (SPT). The data consist of 790 deg^2 of sky observed at 150 GHz during 2008 and 2009. Here we present the power spectrum over the multipole range 650 < ā < 3000, where it is dominated by primary CMB anisotropy. We combine this power spectrum with the power spectra from the seven-year Wilkinson Microwave Anisotropy Probe (WMAP) data release to constrain cosmological models. We find that the SPT and WMAP data are consistent with each other and, when combined, are well fit by a spatially flat, ĪCDM cosmological model. The SPT+WMAP constraint on the spectral index of scalar fluctuations is n_s = 0.9663 Ā± 0.0112. We detect, at ~5Ļ significance, the effect of gravitational lensing on the CMB power spectrum, and find its amplitude to be consistent with the ĪCDM cosmological model. We explore a number of extensions beyond the ĪCDM model. Each extension is tested independently, although there are degeneracies between some of the extension parameters. We constrain the tensor-to-scalar ratio to be r < 0.21 (95% CL) and constrain the running of the scalar spectral index to be dn_s /dln k = ā0.024 Ā± 0.013. We strongly detect the effects of primordial helium and neutrinos on the CMB; a model without helium is rejected at 7.7Ļ, while a model without neutrinos is rejected at 7.5Ļ. The primordial helium abundance is measured to be Y_p = 0.296 Ā± 0.030, and the effective number of relativistic species is measured to be N_eff = 3.85 Ā± 0.62. The constraints on these models are strengthened when the CMB data are combined with measurements of the Hubble constant and the baryon acoustic oscillation feature. Notable improvements include ns = 0.9668 Ā± 0.0093, r < 0.17 (95% CL), and N_eff = 3.86 Ā± 0.42. The SPT+WMAP data show a mild preference for low power in the CMB damping tail, and while this preference may be accommodated by models that have a negative spectral running, a high primordial helium abundance, or a high effective number of relativistic species, such models are disfavored by the abundance of low-redshift galaxy clusters
A Measurement of Secondary Cosmic Microwave Background Anisotropies with Two Years of South Pole Telescope Observations
We present the first three-frequency South Pole Telescope (SPT) cosmic microwave background (CMB) power spectra. The band powers presented here cover angular scales 2000 < ā < 9400 in frequency bands centered at 95, 150, and 220 GHz. At these frequencies and angular scales, a combination of the primary CMB anisotropy, thermal and kinetic Sunyaev-Zel'dovich (SZ) effects, radio galaxies, and cosmic infrared background (CIB) contributes to the signal. We combine Planck/HFI and SPT data at 220 GHz to constrain the amplitude and shape of the CIB power spectrum and find strong evidence for nonlinear clustering. We explore the SZ results using a variety of cosmological models for the CMB and CIB anisotropies and find them to be robust with one exception: allowing for spatial correlations between the thermal SZ effect and CIB significantly degrades the SZ constraints. Neglecting this potential correlation, we find the thermal SZ power at 150 GHz and ā = 3000 to be 3.65 Ā± 0.69 Ī¼K^2, and set an upper limit on the kinetic SZ power to be less than 2.8 Ī¼K^2 at 95% confidence. When a correlation between the thermal SZ and CIB is allowed, we constrain a linear combination of thermal and kinetic SZ power: D^(tSZ)_(3000) + 0.5D^(kSZ)_(3000) = 4.60 Ā± 0.63 Ī¼K^2, consistent with earlier measurements. We use the measured thermal SZ power and an analytic, thermal SZ model calibrated with simulations to determine Ļ_8 = 0.807 Ā± 0.016. Modeling uncertainties involving the astrophysics of the intracluster medium rather than the statistical uncertainty in the measured band powers are the dominant source of uncertainty on Ļ_8. We also place an upper limit on the kinetic SZ power produced by patchy reionization; a companion paper uses these limits to constrain the reionization history of the universe
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