We present the rest-frame Js- and Ks-band luminosity function (LF) of a sample of about 300 galaxies selected in the Hubble Deep Field-South (HDF-S) at Ks≤ 23 (Vega). We use calibrated photometric ...redshift together with spectroscopic redshift for 25 per cent of the sample. The accuracy reached in the photometric redshift estimate is 0.06 (rms) and the fraction of outliers is 1 per cent. We find that the rest-frame Js-band luminosities obtained by extrapolating the observed Js-band photometry are consistent with those obtained by extrapolating the photometry in the redder H and Ks bands closer to the rest-frame Js, at least up to z∼ 2. Moreover, we find no significant differences among the luminosities obtained with different spectral libraries. Thus, our LF estimate is not dependent either on the extrapolation made on the best-fitting template or on the library of models used to fit the photometry. The selected sample has allowed us to probe the evolution of the LF in the three redshift bins 0; 0.8), 0.8; 1.9) and 1.9; 4) centred at the median redshift zm≃0.6, 1.2, 3 and to probe the LF at zm≃ 0.6 down to the unprecedented faint luminosities and . We find hints of a rise of the faint-end ( and ) near-infrared (near-IR) LF at zm∼ 0.6: a rise that cannot be probed at higher redshift with our sample. The values of α we estimate are consistent with the local value and do not show any trend with redshift. We do not see evidence of evolution from z= 0 to zm∼ 0.6 suggesting that the population of local bright galaxies was already formed at z < 0.8. In contrast, we clearly detect an evolution of the LF to zm∼ 1.2 characterized by a brightening of M* and by a decline of φ*. To zm∼ 1.2, M* brightens by about 0.4–0.6 mag and φ* decreases by a factor 2–3. This trend persists, even if at a lesser extent, down to zm∼ 3 in both the Js- and Ks-band LF. The decline of the number density of bright galaxies seen at z > 0.8 suggests that a significant fraction of them increase their stellar mass at 1 < z < 2–3 and that they underwent a strong evolution in this redshift range. On the other hand, this implies also that a significant fraction of local bright/massive galaxies were already in place at z > 3. Thus, our results suggest that the assembly of massive galaxies is spread over a large redshift range and that the increase of their stellar mass has been very efficient also at very high redshift at least for a fraction of them.
In this third paper of a series we present Johnson-Gunn B, g, V, r, i, z multicolour photometry for 79 objects, including a significant fraction of the faintest galaxies around NGC5044, assessing ...group membership on the basis of apparent morphology (through accurate Sérsic-profile fitting) and low-resolution (R= 500-1000) optical spectroscopy to estimate the redshift for 21 objects. Early- and late-type systems are found to be clearly separate in Sérsic parameter space, with the well-known luminosity versus shape relation being mostly traced by different morphological types spanning different ranges in the shape parameter n. A significantly blue colour is confirmed for Magellanic irregulars (Sm/Ims), while a drift toward bluer integrated colours is also an issue for dwarf ellipticals (dEs). Both features point to moderate but pervasive star-formation activity even among nominally 'quiescent' stellar systems. Together, dEs and Ims provide the bulk of the galaxy luminosity function, around M(g) -18.0 ± 1.5, while the S0 and dwarf spheroidal (dSph) components dominate the bright and faint-end tails of the distribution respectively. This special mix places the NGC5044 Group just 'midway' between the high-density cosmic aggregation scale typical of galaxy clusters and the low-density environment of looser galaxy clumps like our Local Group. The bright mass of the 136 member galaxies with available photometry and morphological classification, as inferred from appropriate M/L model fitting, amounts to a total of 2.3 × 1012M. This is one seventh of the total dynamical mass of the group, according to its X-ray emission. The current star-formation rate within the group turns to be about 23Myr-1, a figure that may however be slightly increased as a result of the evident activity among dwarf ellipticals, as shown by enhanced Hbeta emission in their spectra. Lick narrow-band indices have been computed for 17 galaxies, probing all the relevant atomic and molecular features in the 4300-5800Å wavelength range. Dwarf ellipticals are found to share a subsolar metallicity (-1.0 Fe/H - 0.5), with a clear decoupling between iron and alpha elements, as already established for high-mass systems. Both dEs and dS0s are consistent with a high age, about one Hubble time, although a possible bias towards higher values of age may be induced by the gas emission affecting the Hbeta strength. PUBLICATION ABSTRACT
We present a technique for the estimation of photometric redshifts based on feed-forward neural networks. The Multilayer Perceptron (MLP) Artificial Neural Network is used to predict photometric ...redshifts in the HDF-S from an ultra deep-multicolor catalog. Various possible approaches for the training of the neural network are explored, including the deepest and most complete spectroscopic redshift catalog currently available (the Hubble Deep Field North dataset) and models of the spectral energy distribution of galaxies available in the literature. The MLP can be trained on observed data, theoretical data and mixed samples. The prediction of the method is tested on the spectroscopic sample in the HDF-S (44 galaxies). Over the entire redshift range, 0.1 < z < 3.5, the agreement between the photometric and spectroscopic redshifts in the HDF-S is good: the training on mixed data produces sigma super(t) sub(z) super(est) 0.11, showing that model libraries together with observed data provide a sufficiently complete description of the galaxy population. The neural system capability is also tested in a low redshift regime, 0 < z < 0.4, using the Sloan Digital Sky Survey Data Release One (DR1) spectroscopic sample. The resulting accuracy on 88 108 galaxies is sigma super(t) sub(z) super(est) 0.022. Inputs other than galaxy colors - such as morphology, angular size and surface brightness - may be easily incorporated in the neural network technique. An important feature, in view of the application of the technique to large databases, is the computational speed: in the evaluation phase, redshifts of 10 super(5) galaxies are estimated in few seconds.
One hundred consecutive patients with severe aplastic anemia (SAA) received horse antilymphocyte globulin (ALG), cyclosporin A (CyA), 6-methylprednisolone (6Mpred), and granulocyte colony-stimulating ...factor (G-CSF) as first-line therapy. The median age was 16 years (range, 1-72 years) and median neutrophil count was 0.2 × 109/L (range, 0-0.5 × 109/L). Trilineage hematologic recovery (at a median interval of 96 days from treatment) was seen in 77 patients (48 complete, 29 partial) after 1 (n = 50) or more courses of ALG (n = 27). Of the 23 nonresponders, 11 patients died at a median interval of 83 days (range, 16-1132 days), 6 were considered treatment failures and underwent transplantation, and 6 were pancytopenic. Cytogenetic abnormalities were seen in 11% of patients, clonal hematologic disease in 8%, and relapse of marrow aplasia in 9%. The actuarial survival at 5 years was 87% (median follow-up 1424 days): 76% versus 98% for patients with neutrophil counts less than versus greater than 0.2 × 109/L (P = .001) and 88% versus 87% for patients aged less than versus more than 16 years (P = .8). The actuarial probability of discontinuing CyA was 38%. Patients who did not achieve a white blood cell (WBC) count of 5 × 109/L during G-CSF treatment have a low probability of responding (37%) and a high mortality rate (42%). This update confirms a high probability for SAA patients of becoming transfusion independent and of surviving after treatment with ALG, CyA, 6Mpred, and G-CSF, with a significant effect of neutrophil counts on outcome. Problems still remain, such as absent or incomplete responses, clonal evolution, relapse of the original disease, and cyclosporine dependence. Early transplantation, also from alternative donors, may be warranted in patients with poor WBC response to G-CSF.
PIXE Simulation With Geant4 Pia, M.G.; Weidenspointner, G.; Augelli, M. ...
IEEE transactions on nuclear science,
12/2009, Letnik:
56, Številka:
6
Journal Article
Recenzirano
Particle induced X-ray emission (PIXE) is an important physical effect that is not yet adequately modelled in Geant4. This paper provides a critical analysis of the problem domain associated with ...PIXE simulation; it evaluates the conceptual approach, design and implementations of PIXE modelling so far available in Geant4, and describes a set of software developments to improve PIXE simulation with Geant4. The capabilities of the developed software prototype are illustrated and applied to a study of the passive shielding of the X-ray detectors of the German eROSITA telescope on the upcoming Russian Spectrum-X-Gamma space mission.
An Interacting Quark–Diquark Model De Sanctis, M.; Ferretti, J.; Magaña Vsevolodovna, R. ...
Few-body systems,
12/2016, Letnik:
57, Številka:
12
Journal Article
Recenzirano
We describe the relativistic interacting quark–diquark model formalism and its application to the calculation of strange and nonstrange baryon spectra. The results are compared to the existing ...experimental data. We also discuss the application of the model to the calculation of other baryon observables, like baryon magnetic moments, open-flavor strong decays and baryon masses with self-energy corrections.
According to data from the Italian Registry for Childhood Thrombosis (R.I.T.I.), in about half cases diagnosis of pediatric stroke occurs after 24 h from clinical onset (Baggio et al., SINP2013). The ...aim of the present study was to evaluate the frequency of seizures at stroke onset and their correlation with time to diagnosis in the pediatric stroke patients in the R.I.T.I. We selected the R.I.T.I. children with first acute arterial (AIS) or venous (CSVT) cerebral infarction occurring between January 2007 and June 2012; we studied prevalence, characteristics and recurrence of epileptic seizures, focusing on diagnostic delay. At stroke onset, epileptic seizures occurred in 27.27% of the 63 AIS, and in 50% of the 14 CSVT. In the AIS patients with seizures at stroke onset, diagnosis occurred within 6 h in 30.77%, while in only 12.82% of the seizure-free patients. In the CSVT patients with seizures at stroke onset, diagnosis occurred within 6 h in 28.57%, while in only 14.28% of the seizure-free patients. At discharge, relapse of seizures occurred in 28.57% AIS and in 16.67% CSVT groups. Epileptic seizures are common at onset of stroke in childhood, and they correlate with a more timely diagnosis.
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