We combined the spectroscopic information from the 3D-HST survey with \textit{Herschel} data to characterize the H\(\alpha\) dust attenuation properties of a sample of 79 main sequence star-forming ...galaxies at \(z \sim 1\) in the GOODS-S field. The sample was selected in the far-IR, at \(\lambda\)=100 and/or 160 \(\mu\)m, and only includes galaxies with a secure H\(\alpha\) detection (S/N\(>\)3). From the low resolution 3D-HST spectra we measured the redshifts and the H\(\alpha\) fluxes for the whole sample (a factor of 1/1.2 was applied to the observed fluxes to remove the NII contamination). The stellar masses (M\(_{\star}\)), infrared (L\(_{IR}\)) and UV luminosities (L\(_{UV}\)) were derived from the SEDs by fitting multi-band data from GALEX near-UV to SPIRE 500 \(\mu\)m. We estimated the continuum extinction E\(_{star}\)(B-V) from both the IRX=L\(_{IR}\)/L\(_{UV}\) ratio and the UV-slope, \(\beta\), and found an excellent agreement between the two. The nebular extinction was estimated from comparison of the observed SFR\(_{H\alpha}\) and SFR\(_{UV}\). We obtained \emph{f}=E\(_{star}\)(B-V)/E\(_{neb}\)(B-V)=0.93\(\pm\)0.06, i.e. higher than the canonical value of \emph{f}=0.44 measured in the local Universe. Our derived dust correction produces good agreement between the H\(\alpha\) and IR+UV SFRs for galaxies with SFR\(\gtrsim\) 20 M\(_{\odot}\)/yr and M\(_{\star} \gtrsim 5 \times 10^{10}\) M\(_{\odot}\), while objects with lower SFR and M\(_{\star}\) seem to require a smaller \emph{f}-factor (i.e. higher H\(\alpha\) extinction correction). Our results then imply that the nebular extinction for our sample is comparable to that in the optical-UV continuum and suggest that the \emph{f}-factor is a function of both M\(_{\star}\) and SFR, in agreement with previous studies.
Phys. Rev. E 66, 061305 (2002) We study the dynamics of a 2d driven inelastic gas, by means of Direct
Simulation Monte Carlo (DSMC) techniques, i.e. under the assumption of
Molecular Chaos. Under the ...effect of a uniform stochastic driving in the form
of a white noise plus a friction term, the gas is kept in a non-equilibrium
Steady State characterized by fractal density correlations and non-Gaussian
distributions of velocities; the mean squared velocity, that is the so-called
{\em granular temperature}, is lower than the bath temperature. We observe that
a modified form of the Kubo relation, which relates the autocorrelation and the
linear response for the dynamics of a system {\em at equilibrium}, still holds
for the off-equilibrium, though stationary, dynamics of the systems under
investigation. Interestingly, the only needed modification to the equilibrium
Kubo relation is the replacement of the equilibrium temperature with an
effective temperature, which results equal to the global granular temperature.
We present two independent numerical experiment, i.e. two different observables
are studied: (a) the staggered density current, whose response to an impulsive
shear is proportional to its autocorrelation in the unperturbed system and (b)
the response of a tracer to a small constant force, switched on at time $t_w$,
which is proportional to the mean-square displacement in the unperturbed
system. Both measures confirm the validity of Kubo's formula, provided that the
granular temperature is used as the proportionality factor between response and
autocorrelation, at least for not too large inelasticities.
We consider the velocity fluctuations of a system of particles described by the Inelastic Maxwell Model. The present work extends the methods, previously employed to obtain the one-particle velocity ...distribution function, to the study of the two particle correlations. Results regarding both the homogeneous cooling process and the steady state driven regime are presented. In particular we obtain the form of the pair correlation function in the scaling region of the homogeneous cooling process and show that some of its moments diverge. This fact has repercussions on the behavior of the energy fluctuations of the model.
C. R. Physique 8, 641 (2007) A granular gas may be modeled as a set of hard-spheres undergoing inelastic
collisions; its microscopic dynamics is thus strongly irreversible. As pointed
out in several ...experimental works bearing on turbulent flows or granular
materials, the power injected in a dissipative system to sustain a steady-state
over an asymptotically large time window is a central observable. We describe
an analytic approach allowing us to determine the full distribution of the
power injected in a granular gas within a steady-state resulting from
subjecting each particle independently either to a random force (stochastic
thermostat) or to a deterministic force proportional to its velocity (Gaussian
thermostat). We provide an analysis of our results in the light of the
relevance, for other types of systems, of the injected power to fluctuation
relations.
A double-blind study, using metrizamide, iohexol, or Ringer's solution (control) as cisternal myelographic agents, was performed on 25 dogs. Before myelographic examination was done, each dog was ...subjected to physical, clinical pathologic, and neurologic examinations, as well as examinations by electroencephalography and computerized tomography. These were repeated 24 hours after completion of the myelographic examination. The group of dogs given metrizamide (group II) had a significantly greater occurrence of seizure activity (6 of 10) than did the control dogs (group I; 0 of 5) or dogs given iohexol (group III; 0 of 10; P less than 0.003). In group II, the CSF microprotein concentration was significantly greater 24 hours after myelography was done than were the values in groups I and III (P less than 0.003). Myelograms of the group II dogs (metrizamide) and group III dogs (iohexol) had similar diagnostic qualities. At 24 hours after myelographic examination was done, computerized tomography scan revealed that each dog given metrizamide and iohexol had myelographic contrast material in the brain and cervical spinal cord parenchyma. Seemingly, iohexol has good diagnostic quality, but is less epileptogenic than metrizamide when used in cervical myelographic examinations of dogs.
We have performed H and Ks band observations of the planetary system around HR 8799 using the new AO system at the Large Binocular Telescope and the PISCES Camera. The excellent instrument ...performance (Strehl ratios up to 80% in H band) enabled detection the inner planet HR8799e in the H band for the first time. The H and Ks magnitudes of HR8799e are similar to those of planets c and d, with planet e slightly brighter. Therefore, HR8799e is likely slightly more massive than c and d. We also explored possible orbital configurations and their orbital stability. We confirm that the orbits of planets b, c and e are consistent with being circular and coplanar; planet d should have either an orbital eccentricity of about 0.1 or be non-coplanar with respect to b and c. Planet e can not be in circular and coplanar orbit in a 4:2:1 mean motion resonances with c and d, while coplanar and circular orbits are allowed for a 5:2 resonance. The analysis of dynamical stability shows that the system is highly unstable or chaotic when planetary masses of about 5 MJup for b and 7 MJup for the other planets are adopted. Significant regions of dynamical stability for timescales of tens of Myr are found when adopting planetary masses of about 3.5, 5, 5, and 5 Mjup for HR 8799 b, c, d, and e respectively. These masses are below the current estimates based on the stellar age (30 Myr) and theoretical models of substellar objects.
