13,703 research outputs found
Astrophysical and Cosmological Information from Large-scale sub-mm Surveys of Extragalactic Sources
We present a quantitative analysis of the astrophysical and cosmological
information that can be extracted from the many important wide-area, shallow
surveys that will be carried out in the next few years. Our calculations
combine the predictions of the physical model by Granato et al. (2004) for the
formation and evolution of spheroidal galaxies with up-to-date phenomenological
models for the evolution of starburst and normal late-type galaxies and of
radio sources. We compute the expected number counts and the redshift
distributions of these source populations separately and then focus on
proto-spheroidal galaxies. For the latter objects we predict the counts and
redshift distributions of strongly lensed sources at 250, 350, 500, and 850
micron, the angular correlation function of sources detected in the surveys
considered, the angular power spectra due to clustering of sources below the
detection limit in Herschel and Planck surveys. An optimal survey for selecting
strongly lensed proto-spheroidal galaxies is described, and it is shown how
they can be easily distinguished from the other source populations. We also
discuss the detectability of the imprints of the 1-halo and 2-halo regimes on
angular correlation functions and clustering power spectra, as well as the
constraints on cosmological parameters that can be obtained from the
determinations of these quantities. The novel data relevant to derive the first
sub-millimeter estimates of the local luminosity functions of starburst and
late-type galaxies, and the constraints on the properties of rare source
populations, such as blazars, are also briefly described.Comment: 16 pages, 10 figures. Accepted for publication on MNRA
Pressure effect in the X-ray intrinsic position resolution in noble gases and mixtures
A study of the gas pressure effect in the position resolution of an
interacting X- or gamma-ray photon in a gas medium is performed. The intrinsic
position resolution for pure noble gases (Argon and Xenon) and their mixtures
with CO2 and CH4 were calculated for several gas pressures (1-10bar) and for
photon energies between 5.4 and 60.0 keV, being possible to establish a linear
match between the intrinsic position resolution and the inverse of the gas
pressure in that energy range. In order to evaluate the quality of the method
here described, a comparison between the available experimental data and the
calculated one in this work, is done and discussed. In the majority of the
cases, a strong agreement is observed
Caveolin-1 is a risk factor for postsurgery metastasis in preclinical melanoma models
Melanomas are highly lethal skin tumours that are frequently treated by surgical resection. However, the efficacy of such procedures is often limited by tumour recurrence and metastasis. Caveolin-1 (CAV1) has been attributed roles as a tumour suppressor, although in late-stage tumours, its presence is associated with enhanced metastasis. The expression of this protein in human melanoma development and particularly how the presence of CAV1 affects metastasis after surgery has not been defined. CAV1 expression in human melanocytes and melanomas increases with disease progression and is highest in metastatic melanomas. The effect of increased CAV1 expression can then be evaluated using B16F10 murine melanoma cells injected into syngenic immunocompetent C57BL/6 mice or human A375 melanoma cells injected into immunodeficient B6Rag1−/− mice. Augmented CAV1 expression suppresses tumour formation upon a subcutaneous injection, but enhances lung metastasis of cells injected into the tail vein in both models. A procedure was initially developed using B16F10 melanoma cells in C57BL/6 mice to mimic better the situation in patients undergoing surgery. Subcutaneous tumours of a defined size were removed surgically and local tumour recurrence and lung metastasis were evaluated after another 14 days. In this postsurgery setting, CAV1 presence in B16F10 melanomas favoured metastasis to the lung, although tumour suppression at the initial site was still evident. Similar results were obtained when evaluating A375 cells in B6Rag1−/− mice. These results implicate CAV1 expression in melanomas as a marker of poor prognosis for patients undergoing surgery as CAV1 expression promotes experimental lung metastasis in two different preclinical models
Evolved stars hint to an external origin of enhanced metallicity in planet-hosting stars
Exo-planets are preferentially found around high metallicity main sequence
stars. We aim at investigating whether evolved stars share this property, and
what this tells about planet formation. Statistical tools and the basic
concepts of stellar evolution theory are applied to published results as well
as our own radial velocity and chemical analyses of evolved stars. We show that
the metal distributions of planet-hosting (P-H) dwarfs and giants are
different, and that the latter do not favor metal-rich systems. Rather, these
stars follow the same age-metallicity relation as the giants without planets in
our sample. The straightforward explanation is to attribute the difference
between dwarfs and giants to the much larger masses of giants' convective
envelopes. If the metal excess on the main sequence is due to pollution, the
effects of dilution naturally explains why it is not observed among evolved
stars. Although we cannot exclude other explanations, the lack of any
preference for metal-rich systems among P-H giants could be a strong indication
of the accretion of metal-rich material. We discuss further tests, as well as
some predictions and consequences of this hypothesis.Comment: A&A, in pres
Danos causados por ovelhas em árvores de eucalipto em um sistema silvipastoril distribuido em dois modelos espaciais.
O experimento foi realizado na Unidade de Pesquisa e Desenvolvimento de Itapetininga da Agência Paulista de Tecnologia dos Agronegócios, Itapetininga, SP, Brasil. Avaliou-se o efeito do impacto das ovelhas nas árvores em um sistema silvipastoril em dois modelos de distribuição espacial de plantio do eucalipto (em fileira única ou em fileira dupla) e do manejo de desrama (com ou sem desrama). As variáveis Danos, Altura e Altura do Dano forma afetadas significativamente pela interação modelo espacial e manejo de desrama. O modelo espacial Fileira Dupla com Desrama apresentou menor nota atribuÃda a danos observados nas árvores (p<0,05). A altura (H) também foi menor no modelo espacial Fileira Dupla com desrama e a Altura do Dano foi menor para o modelo espacial fileira dupla com desrama e sem desrama. A análise dos resultados mostrou não ter havido interação entre modelo espacial e manejo de desrama para o diâmetro a altura do peito (DAP). Para a DAP foi verificado efeito significativo apenas para o fator desrama, ou seja, a DAP foi maior nas árvores que não sofreram desrama. O dano de maior incidência nesse sistema foi o de casca lesionada e ruÃda (Cl, 85,66% das árvores avaliadas). Os tratamentos que foram realizadas a desrama não sofreram o dano quebra de ramos em função da altura que foi realizada a desrama. Apesar de não ter comprometido o desenvolvimento do eucalipto, as ovelhas (animais adultos) danificam severamente as árvores dentro do sistema silvipastoril. Futuros estudos devem ser planejados para entendermos melhor qual o fator de atração para o consumo da casca das árvores de eucalipto
The CHilean Automatic Supernova sEarch (CHASE)
The CHASE project started in 2007 with the aim of providing young southern
supernovae (SNe) to the Carnegie Supernova Project (CSP) and Millennium Center
for Supernova Studies (MCSS) follow-up programs. So far CHASE has discovered 33
SNe with an average of more than 2.5 SNe per month in 2008. In addition to the
search we are carrying out a follow-up program targeting bright SNe. Our fully
automated data reduction allows us to follow the evolution on the light curve
in real time, triggering further observations if something potentially
interesting is detectedComment: 4 pages, 2 figures, conference proceedin
Elodie metallicity-biased search for transiting Hot Jupiters IV. Intermediate period planets orbiting the stars HD43691 and HD132406
We report here the discovery of two planet candidates as a result of our
planet-search programme biased in favour of high-metallicity stars, using the
ELODIE spectrograph at the Observatoire de Haute Provence. One of them has a
minimum mass m_2\sin{i} = 2.5 M_Jup and is orbiting the metal-rich star HD43691
with period P = 40 days and eccentricity e = 0.14. The other planet has a
minimum mass m_2\sin{i} = 5.6 M_Jup and orbits the slightly metal-rich star
HD132406 with period P = 974 days and eccentricity e = 0.34. Both stars were
followed up with additional observations using the new SOPHIE spectrograph that
replaces the ELODIE instrument, allowing an improved orbital solution for the
systems.Comment: 6 pages, 4 figures, to be published in A&
Observations of the Hubble Deep Field South with the Infrared Space Observatory - II. Associations and star formation rates
We present results from a deep mid-IR survey of the Hubble Deep Field South
(HDF-S) region performed at 7 and 15um with the CAM instrument on board ISO. We
found reliable optical/near-IR associations for 32 of the 35 sources detected
in this field by Oliver et al. (2002, Paper I): eight of them were identified
as stars, one is definitely an AGN, a second seems likely to be an AGN, too,
while the remaining 22 appear to be normal spiral or starburst galaxies. Using
model spectral energy distributions (SEDs) of similar galaxies, we compare
methods for estimating the star formation rates (SFRs) in these objects,
finding that an estimator based on integrated (3-1000um) IR luminosity
reproduces the model SFRs best. Applying this estimator to model fits to the
SEDs of our 22 spiral and starburst galaxies, we find that they are forming
stars at rates of ~1-100 M_sol/yr, with a median value of ~40M_sol/yr, assuming
an Einstein - de Sitter universe with a Hubble constant of 50 km/s/Mpc, and
star formation taking place according to a Salpeter (1955) IMF across the mass
range 0.1-100M_sol. We split the redshift range 0.0<z<0.6 into two equal-volume
bins to compute raw estimates of the star formation rate density contributed by
these sources, assuming the same cosmology and IMF as above and computing
errors based on estimated uncertainties in the SFRs of individual galaxies. We
compare these results with other estimates of the SFR density made with the
same assumptions, showing them to be consistent with the results of Flores et
al. (1999) from their ISO survey of the CFRS 1415+52 field. However, the
relatively small volume of our survey means that our SFR density estimates
suffer from a large sampling variance, implying that our results, by
themselves, do not place tight constraints on the global mean SFR density.Comment: Accepted for MNRAS. 23 pages, 10 figures (Figs. 4&6 included here as
low resolution JPEGS), latex, uses mn,epsfig. Further information and full
resolution versions of Figs 4&6 available at http://astro.ic.ac.uk/hdfs (v2:
full author list added
Effect of extended postmortem aging and steak location on myofibrillar protein degradation and Warner-Bratzler shear force of beef M. semitendinosus steaks
Citation: Phelps, K. J., Drouillard, J. S., Silva, M. B., Miranda, L. D. F., Ebarb, S. M., Van Bibber-Krueger, C. L., . . . Gonzalez, J. M. (2016). Effect of extended postmortem aging and steak location on myofibrillar protein degradation and Warner-Bratzler shear force of beef M. semitendinosus steaks. Journal of Animal Science, 94(1), 412-423. doi:10.2527/jas2015-9862The objective of this study was to evaluate the effect of steak location and postmortem aging on cooked meat tenderness and myofibrillar protein degradation of steaks from M. semitendinosus (ST). Following harvest and a 6 d chill period, the left ST was removed from carcasses of crossbred feedlot steers (n = 60, average hot carcass weight 427 +/- 24 kg). Each ST was fabricated into ten 2.54-cm thick steaks originating from the proximal to distal end of the muscle. Steaks cut adjacent to each other were paired, vacuum packaged, and randomly assigned to 7, 14, 21, 42, or 70 d of aging at 2 +/- 1 degrees C. After aging, within each steak pair, steaks were randomly assigned to Warner-Bratzler shear force or myofibrillar proteolysis analysis (calpain activity and desmin and troponin-T degradation). Muscle fiber type and size were also determined at the 2 ends of the muscle. There was no location x d of aging interaction (P = 0.25) for ST steak WBSF. Steak location affected (quadratic, P 0.13). Type I, IIA, and IIX muscle fibers were larger at the proximal end of the muscle than the distal end (P < 0.01). Increasing d of aging improved WBSF (quadratic, P < 0.01) for the duration of the 70 d postmortem period. As d of aging increased, intact calpain-1 activity decreased (quadratic, P < 0.01) with activity detected through 42 d. Day of aging affected autolyzed calpain-1 (linear, P < 0.01) and calpain-2 activity (quadratic, P < 0.01). Through d 70 of aging, the intensity of intact 55 kDa desmin band decreased (linear, P < 0.01), while there was an increase (linear, P < 0.01) in the degraded 38 kDa band. Similarly, d of aging increased troponin-T proteolysis, indicated by a decrease (quadratic, P < 0.01) in intensity of the intact 40 kDa band and an increase (linear, P < 0.01) in the 30 kDa degraded band. Intramuscular WBSF differences are not due to proteolytic activity or myofibrillar degradation and seem related to muscle fiber size. The improvement of ST steak WBSF through 70 d of aging is partly due to continued degradation of desmin and troponin-T. Calpain proteolytic analysis indicates that autolyzed calpain-1 and calpain-2 may be involved in extended postmortem myofibrillar protein proteolysis
- …