283 research outputs found
A Determination of the Hubble Constant from Cepheid Distances and a Model of the Local Peculiar Velocity Field
We present a measurement of the Hubble Constant based on Cepheid distances to
27 galaxies within 20 Mpc. We take the Cepheid data from published measurements
by the Hubble Telescope Key Project on the Distance Scale (H0KP). We calibrate
the Cepheid Period-Luminosity (PL) relation with data from over 700 Cepheids in
the LMC obtained by the OGLE collaboration; we assume an LMC distance modulus
of 18.50 mag (d=50.1 kpc). Using this PL calibration we obtain new distances to
the H0KP galaxies. We correct the redshifts of these galaxies for peculiar
velocities using two distinct velocity field models: the phenomenological model
of Tonry et al. and a model based on the IRAS density field and linear
gravitational instability theory. We combine the Cepheid distances with the
corrected redshifts for the 27 galaxies to derive H_0, the Hubble constant. The
results are H_0 = 85 +/- 5 km/s/Mpc (random error) at 95% confidence when the
IRAS model is used, and 92 +/- 5 km/s/Mpc when the phenomenological model is
used. The IRAS model is a better fit to the data and the Hubble constant it
returns is more reliable. Systematic error stems mainly from LMC distance
uncertainty which is not directly addressed by this paper. Our value of H_0 is
significantly larger than that quoted by the H0KP, H_0 = 71 +/- 6 km/s/Mpc.
Cepheid recalibration explains ~30% of this difference, velocity field analysis
accounts for ~70%. We discuss in detail possible reasons for this discrepancy
and future study needed to resolve it.Comment: 33 pages, 8 embedded figures. New table, 5 new references, text
revision
extracellular enzymatic activities of 32 fungal species
Se investigó en 32 especies fúngicas, la producción de enzimas extracelulares y ms determinaciones cualitativas (amilasa, celulosa, caseinasa, fosfatasa, lipasa, pectinasa y ureasa). La detección de los enzimas en los cultivos fúngicos en agar varió ampliamente.En la mayoría de los cultivos fúngicos se detectaron: amilasas, ureasas, y fosfatasas. Las celulosas se pesquizaron particularmente en cultivo de Aspergillus flavus, A. fumigatus, Cladosporium cladosporioides Penicillium brevicompactum, Rhizopus stolonifer, Scopulariopsis flava y Trichothecium roseum. Penicillium digitatum y P.duclauxi fueron productores de caseinasa en un alto grado. La actividad lipolítica se detectó en cultivos con grasas sintéticas tweens 20, 40, 60, y 80 como sustrato para lipasa. Indicaron actividad lipolítico para estos sustratos A. flavus, Aureobasidium pullulans, C. cladosporioides, Gliocladium roseum, Mycothypha microspora, Microsporum gypseum, P. brevicompactum y Scopulariopsis brumptii. Productores de pectinasas fueron las cepas de A. flavus, C. cladosporioides y Fusarium oxysporum, P. brevicompoctum y Ulocladium atru
Hongos aislados del plumaje y excremento de gallinas en una industria avícola de Monferrato (Pavia- Italia)
Mediante cultivos en sustratos queratínicos, diluciones en PDA y un medio selectivo para Cryptococcus neoformans, se evaluó durante 2 períodos estacionales en una industria avicola, la micota presente en el plumaje y excrementos de gallinas sanas y enfermas, con la finalidadde evaluar la frecuencia de presencia de algunos hongos considerados potencialmente patógenos o toxicogénicos.En el plumaje de las aves sanas predominaron Aspergillus fumigatus, A. niger y Penicillium glabrum, mientras en sus excrementos Candida famata, C. guilliermondi, Cryptococcus laurentii, Mucor hiemalis y M. racemosus.El plumaje de las aves enfermas presentó una mayor diversidad de especies, dominando: A. niger, P. purpurogenum, Fusarium equiseti, Chrysosporium keratinophilum, Chry. indicum, mientras en los excrementos, A. flavus, A. clavatus, A. fumigatus, M. hiemalis y M.racemosus, Candida albicans, C. pseudotropicalis y Cryptococcuslaurentii. Cryptococcus neoformans var. neoformans, se aisló con baja frecuencia en las heces.Estas aves y su habitat, constituyen un ambiente vinculado a la ecología de algunos hongos filamentosos y levaduriformes con capacidad toxicogénica o invasiva, representando un reservorio y una fuente de infección para las aves y el personal de estas industrias
Interprofessional collaboration between different health care professions in emilia romagna
Background and aim of the work: Interprofessional collaboration in the healthcare sector contributes to the delivery of high quality and safe services to patients across different subdivisions of the healthcare system which is faced with constant challenges. The international literature offers a plethora of tools for assessing the collaboration between health workers, but only a few of these have been validated in the Italian language. One that has undergone such validation is the interprofessional collaboration (IPC) scale, which measures the perception of collaboration among health professionals. An advantage of this scale is that is addresses all workers within the system, and is not limited to specific professions. The aim of the present study was to apply the validated Italian version of the IPC scale, to a context different to the one used for its validation, to measure the level of collaboration between different health care workers. Method: A questionnaire-based study was conducted on a sample consisting of 329 health professionals working at Azienda USL-IRCCS in Reggio Emilia. The categorical and continuous variables were analysed using descriptive statistics (frequen-cies, percentages and standard deviations). Results: The IPC scale showed physicians to express the highest level of collaboration with other professionals, in line with the results of other studies in the literature. The values calculated for the factors “accommodation” and “communication” were higher than for “isolation”, de-picting a good level collaboration. The only case in which the isolation factor, which describes an absence of collaboration, was equal to the other two factors was in relation to the evaluation of midwives by nursing aides/orderlies. Conclusions: In conclusion, the Italian version of the IPC scale provides a useful instrument for measuring interprofessional collaboration between workers in the healthcare sector. In the present study, it revealed a satisfactory level of collaboration between health professionals in an organization located in Emilia Romagna, Italy. (www.actabiomedica.it)
Ultrafast Ge-Te bond dynamics in a phase-change superlattice
A long-standing question for avant-garde data storage technology concerns the nature of the ultrafast photoinduced phase transformations in the wide class of chalcogenide phase-change materials (PCMs). Overall, a comprehensive understanding of the microstructural evolution and the relevant kinetics mechanisms accompanying the out-of-equilibrium phases is still missing. Here, after overheating a phase-change chalcogenide superlattice by an ultrafast laser pulse, we indirectly track the lattice relaxation by time resolved x-ray absorption spectroscopy (tr-XAS) with a sub-ns time resolution. The approach to the tr-XAS experimental results reported in this work provides an atomistic insight of the mechanism that takes place during the cooling process; meanwhile a first-principles model mimicking the microscopic distortions accounts for a straightforward representation of the observed dynamics. Finally, we envisage that our approach can be applied in future studies addressing the role of dynamical structural strain in PCMs.M.M. acknowledges the support of the BACH beamline staff during the synchrotron experiments and Roberta Ciprian for insightful discussions. This work was supported by EU within FP7 project PASTRY [GA 317764]
A Quantitative Evaluation of the Galaxy Component of COSMOS and APM Catalogs
We have carried out an independent quantitative evaluation of the galaxy
component of the "COSMOS/UKST Southern Sky Object Catalogue" (SSC) and the
"APM/UKST J Catalogue" (APM). Using CCD observations our results corroborate
the accuracy of the photometry of both catalogs, which have an overall
dispersion of about 0.2 mag in the range 17 <= b_J <= 21.5. The SSC presents
externally calibrated galaxy magnitudes that follow a linear relation, while
the APM instrumental magnitudes of galaxies, only internally calibrated by the
use of stellar profiles, require second-order corrections. The completeness of
both catalogs in a general field falls rapidly fainter than b_J = 20.0, being
slightly better for APM. The 90% completeness level of the SSC is reached
between b_J = 19.5 and 20.0, while for APM this happens between b_J = 20.5 and
21.0. Both SSC and APM are found to be less complete in a galaxy cluster field.
Galaxies misclassified as stars in the SSC receive an incorrect magnitude
because the stellar ones take saturation into account besides using a different
calibration curve. In both cases, the misclassified galaxies show a large
diversity of colors that range from typical colors of early-types to those of
blue star-forming galaxies. A possible explanation for this effect is that it
results from the combination of low sampling resolutions with properties of the
image classifier for objects with characteristic sizes close to the
instrumental resolution. We find that the overall contamination by stars
misclassified as galaxies is < 5% to b_J = 20.5, as originally estimated for
both catalogs. Although our results come from small areas of the sky, they are
extracted from two different plates and are based on the comparison with two
independent datasets.Comment: 14 pages of text and tables, 8 figures; to be published in the
Astronomical Journal; for a single postscript version file see
ftp://danw.on.br/outgoing/caretta/caretta.p
The Aquarius Superclusters - I. Identification of Clusters and Superclusters
We study the distribution of galaxies and galaxy clusters in a 10^deg x 6^deg
field in the Aquarius region. In addition to 63 clusters in the literature, we
have found 39 new candidate clusters using a matched-filter technique and a
counts-in-cells analysis. From redshift measurements of galaxies in the
direction of these cluster candidates, we present new mean redshifts for 31
previously unobserved clusters, while improved mean redshifts are presented for
35 other systems. About 45% of the projected density enhancements are due to
the superposition of clusters and/or groups of galaxies along the line of
sight, but we could confirm for 72% of the cases that the candidates are real
physical associations similar to the ones classified as rich galaxy clusters.
On the other hand, the contamination due to galaxies not belonging to any
concentration or located only in small groups along the line of sight is ~ 10%.
Using a percolation radius of 10 h^{-1} Mpc (spatial density contrast of about
10), we detect two superclusters of galaxies in Aquarius, at z = 0.086 and at z
= 0.112, respectively with 5 and 14 clusters. The latter supercluster may
represent a space overdensity of about 160 times the average cluster density as
measured from the Abell et al. (1989) cluster catalog, and is possibly
connected to a 40 h^{-1} Mpc filament from z ~ 0.11 to 0.14.Comment: LateX text (21 pages) and 12 (ps/eps/gif) figures; figures 5a, 5b and
6 are not included in the main LateX text; to be published in the
Astronomical Journal, March issu
A Very Intense Neutrino Super Beam Experiment for Leptonic CP Violation Discovery based on the European Spallation Source Linac: A Snowmass 2013 White Paper
Very intense neutrino beams and large neutrino detectors will be needed in
order to enable the discovery of CP violation in the leptonic sector. We
propose to use the proton linac of the European Spallation Source currently
under construction in Lund, Sweden to deliver, in parallel with the spallation
neutron production, a very intense, cost effective and high performance
neutrino beam. The baseline program for the European Spallation Source linac is
that it will be fully operational at 5 MW average power by 2022, producing 2
GeV 2.86 ms long proton pulses at a rate of 14 Hz. Our proposal is to upgrade
the linac to 10 MW average power and 28 Hz, producing 14 pulses/s for neutron
production and 14 pulses/s for neutrino production. Furthermore, because of the
high current required in the pulsed neutrino horn, the length of the pulses
used for neutrino production needs to be compressed to a few s with the
aid of an accumulator ring. A long baseline experiment using this Super Beam
and a megaton underground Water Cherenkov detector located in existing mines
300-600 km from Lund will make it possible to discover leptonic CP violation at
5 significance level in up to 50% of the leptonic Dirac CP-violating
phase range. This experiment could also determine the neutrino mass hierarchy
at a significance level of more than 3 if this issue will not already
have been settled by other experiments by then. The mass hierarchy performance
could be increased by combining the neutrino beam results with those obtained
from atmospheric neutrinos detected by the same large volume detector. This
detector will also be used to measure the proton lifetime, detect cosmological
neutrinos and neutrinos from supernova explosions. Results on the sensitivity
to leptonic CP violation and the neutrino mass hierarchy are presented.Comment: 28 page
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