398 research outputs found
Potential Nighttime Contamination of CERES Clear-sky Field of View by Optically Thin Cirrus during the CRYSTAL-FACE Campaign
We investigate the outgoing broadband longwave (LW, 5 to approx. 200 microns) and window (WIN, 8 to approx. 12 microns) channel radiances at the top of atmosphere (TOA) under clear-sky conditions, using data acquired by the Cloud and the Earth s Radiant Energy System (CERES) and Moderate-Resolution Imaging Spectroradiometer (MODIS) instruments onboard the NASA Terra satellite platform. In this study, detailed analyses are performed on the CERES Single Scanner Footprint TOA/Surface Fluxes and Clouds product to understand the radiative effect of thin cirrus. The data are acquired over the Florida area during the Cirrus Regional Study of Tropical Anvils and Cirrus Layers Florida Area Cirrus Experiment (CRYSTAL-FACE) field program. Of particular interest is the anisotropy associated with the radiation field. Measured CERES broadband radiances are compared to those obtained from rigorous radiative transfer simulations. Analysis of results from this comparison indicates that the simulated radiances tend to be larger than their measured counterparts, with differences ranging from 2.1% to 8.3% for the LW band and from 1.7% to 10.6% for the WIN band. The averaged difference in radiance is approximately 4% for both the LW and WIN channels. A potential cause for the differences could be the presence of thin cirrus (i.e., optically thin ice clouds with visible optical thicknesses smaller than approximately 0.3). The detection and quantitative analysis of these thin cirrus clouds are challenging even with sophisticated multispectral instruments. While large differences in radiance between the CERES observations and the theoretical calculations are found, the corresponding difference in the anisotropic factors is very small (0.2%). Furthermore, sensitivity studies show that the influence due to a 1 K bias of the surface temperature on the errors of the LW and WIN channel radiances is of the same order as that associated with a 2% bias of the surface emissivity. The LW and WIN errors associated with a 5% bias of water vapor amount in the lower atmosphere in conjunction with a 50% bias of water vapor amount in the upper atmosphere is similar to that of a 1 K bias of the vertical temperature profile. Even with the uncertainties considered for these various factors, the simulated LW and WIN radiances are still larger than the observed radiances if thin cirrus clouds are excluded
Breast cancer research and the European Union Clinical Trials Directive
Running clinical trials in the commercial sector has always been associated with a certain amount of bureaucracy due to the stringent requirements needed to bring a new drug onto the market. Noncommercial trials have largely been performed outside these requirements. New legislation brought about as a result of the implementation of the European Union Clinical Trials Directive will change this two-tiered approach by harmonizing regulations in all member states. Those who run noncommercial clinical trials will have to find cost-effective ways of dealing with this legislation if such work is to continue in Europe
The puzzling case of the radio-loud QSO 3C 186: a gravitational wave recoiling black hole in a young radio source?
Context. Radio-loud AGNs with powerful relativistic jets are thought to be
associated with rapidly spinning black holes (BHs). BH spin-up may result from
a number of processes, including accretion of matter onto the BH itself, and
catastrophic events such as BH-BH mergers. Aims. We study the intriguing
properties of the powerful (L_bol ~ 10^47 erg s^-1) radio-loud quasar 3C 186.
This object shows peculiar features both in the images and in the spectra.
Methods. We utilize near-IR Hubble Space Telescope (HST) images to study the
properties of the host galaxy, and HST UV and Sloan Digital Sky Survey optical
spectra to study the kinematics of the source. Chandra X-ray data are also used
to better constrain the physical interpretation. Results. HST imaging shows
that the active nucleus is offset by 1.3 +- 0.1 arcsec (i.e. ~11 kpc) with
respect to the center of the host galaxy. Spectroscopic data show that the
broad emission lines are offset by -2140 +-390 km/s with respect to the narrow
lines. Velocity shifts are often seen in QSO spectra, in particular in
high-ionization broad emission lines. The host galaxy of the quasar displays a
distorted morphology with possible tidal features that are typical of the late
stages of a galaxy merger. Conclusions. A number of scenarios can be envisaged
to account for the observed features. While the presence of a peculiar outflow
cannot be completely ruled out, all of the observed features are consistent
with those expected if the QSO is associated with a gravitational wave (GW)
recoiling BH. Future detailed studies of this object will allow us to confirm
this type of scenario and will enable a better understanding of both the
physics of BH-BH mergers and the phenomena associated with the emission of GW
from astrophysical sources.Comment: 16 pages, 8 figures. Accepted for publication in Astronomy &
Astrophysics. New appendix adde
Improved Photometric Redshifts with Surface Luminosity Priors
We apply Bayesian statistics with prior probabilities of galaxy surface
luminosity (SL) to improve photometric redshifts. We apply the method to a
sample of 1266 galaxies with spectroscopic redshifts in the GOODS North and
South fields at 0.1 < z < 2.0. We start with spectrophotometric redshifts
(SPZs) based on Probing Evolution and Reionization Spectroscopically grism
spectra, which cover a wavelength range of 6000-9000A, combined with
(U)BViz(JHK) broadband photometry in the GOODS fields. The accuracy of SPZ
redshifts is estimated to be \sigma (\Delta(z))=0.035 with an systematic offset
of -0.026, where \Delta(z)=\Delta z / (1+z), for galaxies in redshift range of
0.5 < z < 1.25. The addition of the SL prior probability helps break the
degeneracy of SPZ redshifts between low redshift 4000 A break galaxies and
high-redshift Lyman break galaxies which are mostly catastrophic outliers. For
the 1138 galaxies at z < 1.6, the fraction of galaxies with redshift deviation
\Delta (z) > 0.2 is reduced from 15.0% to 10.4%, while the rms scatter of the
fractional redshift error does not change much.Comment: 7 pages, 7 figures, published in A
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Development, Operation, and Results From the Texas Automated Buoy System
The Texas Automated Buoy System (TABS) is a coastal network of moored buoys that report near-real-time observations about currents and winds along the Texas coast. Established in 1995, the primary mission of TABS is ocean observations in the service of oil spill preparedness and response. The state of Texas funded the system with the intent of improving the data available to oil spill trajectory modelers. In its 12 years of operation, TABS has proven its usefulness during realistic oil spill drills and actual spills. The original capabilities of TABS, i.e., measurement of surface currents and temperatures, have been extended to the marine surface layer, the entire water column, and the sea floor. In addition to observations, a modeling component has been integrated into the TABS program. The goal is to form the core of a complete ocean observing system for Texas waters. As the nation embarks on the development of an integrated ocean observing system, TABS will continue to be an active participant of the Gulf of Mexico Coastal Ocean Observing System (GCOOS) regional association and the primary source of near-surface current measurements in the northwestern Gulf of Mexico. This article describes the origin of TABS, the philosophy behind the operation and development of the system, the resulting modifications to improve the system, the expansion of the system to include new sensors, the development of TABS forecasting models and real-time analysis tools, and how TABS has met many of the societal goals envisioned for GCOOS
Cooling by Heat Conduction Inside Magnetic Flux Loops and the Moderate Cluster Cooling Flow Model
I study non-radiative cooling of X-ray emitting gas via heat conduction along
magnetic field lines inside magnetic flux loops in cooling flow clusters of
galaxies. I find that such heat conduction can reduce the fraction of energy
radiated in the X-ray band by a factor of 1.5-2. This non-radiative cooling
joins two other proposed non-radiative cooling processes, which can be more
efficient. These are mixing of cold and hot gas, and heat conduction initiated
by magnetic fields reconnection between hot and cold gas. These processes when
incorporated into the moderate cooling flow model lead to a general cooling
flow model with the following ingredients. (1) Cooling flow does occur, but
with a mass cooling rate about 10 times lower than in old versions of the
cooling flow model. Namely, heating occurs such that the effective age of the
cooling flow is much below the cluster age, but the heating can't prevent
cooling altogether. (2) The cooling flow region is in a non-steady state
evolution. (3) Non-radiative cooling of X-ray emitting gas can bring the model
to a much better agreement with observations. (4) The general behavior of the
cooling flow gas, and in particular the role played by magnetic fields, make
the intracluster medium in cooling flow clusters similar in some aspects to the
active solar corona.Comment: Submitted to MNRA
Development and Validation of a Modified Multiple Errands Test for Adults with Intellectual Disabilities
Background: The aims of the current study were to adapt a version of the MET for people with intellectual disabilities (IDs) and assess its ecological and construct validity. Material and Methods: Using a correlational design, 40 participants with IDs were invited to complete a battery of neuropsychological assessments and the modified Multiple Errands Test for Intellectual Disabilities (mMET-IDs). Results: The ability to successfully complete tasks on the mMET-IDs correlated significantly with measures of the Supervisory Attentional System, namely, the Tower of London Test and the Six Parts Test. However, performance on the mMET-IDs and the Six Parts Test could be accounted for by Verbal IQ and receptive vocabulary. The mMET-IDs failed to correlate with the DEX-IR. Conclusions: The mMET-IDs can be successfully used to assess some aspects of the Supervisory Attentional System in people with IDs. Further development is needed, however, to improve the ecological validity of the mMET-IDs
É necessário mudar a perspectiva sobre o câncer de mama: afastar o rastreamento e priorizar a agilidade no diagnóstico e tratamento
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