423 research outputs found
Peering through the holes: the far UV color of star-forming galaxies at z~3-4 and the escaping fraction of ionizing radiation
We aim to investigate the effect of the escaping ionizing radiation on the
color selection of high redshift galaxies and identify candidate Lyman
continuum (LyC) emitters. The intergalactic medium prescription of Inoue et
al.(2014) and galaxy synthesis models of Bruzual&Charlot (2003) have been used
to properly treat the ultraviolet stellar emission, the stochasticity of the
intergalactic transmission and mean free path in the ionizing regime. Color
tracks are computed by turning on/off the escape fraction of ionizing
radiation. At variance with recent studies, a careful treatment of IGM
transmission leads to no significant effects on the high-redshift broad-band
color selection. The decreasing mean free path of ionizing photons with
increasing redshift further diminishes the contribution of the LyC to
broad-band colors. We also demonstrate that prominent LyC sources can be
selected under suitable conditions by calculating the probability of a null
escaping ionizing radiation. The method is applied to a sample of galaxies
extracted from the GOODS-S field. A known LyC source at z=3.795 is successfully
recovered as a LyC emitter candidate and another convincing candidate at
z=3.212 is reported. A detailed analysis of the two sources (including their
variability and morphology) suggests a possible mixture of stellar and
non-stellar (AGN) contribution in the ultraviolet. Conclusions: Classical
broad-band color selection of 2.5<z<4.5 galaxies does not prevent the inclusion
of LyC emitters in the selected samples. Large fesc in relatively bright
galaxies (L>0.1L*) could be favored by the presence of a faint AGN not easily
detected at any wavelength. A hybrid stellar and non-stellar (AGN) ionizing
emission could coexist in these systems and explain the tensions found among
the UV excess and the stellar population synthesis models reported in
literature.Comment: Accepted for publication in Astronomy & Astrophysics. 13 pages, 7
figure
Use of polyaspartates for the tartaric stabilisation of white and red wines and side effects on wine characteristics
Aim: The stabilising efficacy against tartaric precipitations of polyaspartates-based products (PAs), in particular potassium polyaspartate (KPA), was tested with six different wines (three white and three red). Some side effects on wine characteristics (white wine colour stability, wine turbidity and filterability) were also studied.
Results and conclusions: All PAs showed good stabilising efficacy against tartaric precipitations according to the cold test. With the same test, the PAs were stable in wine for 1 year of storage, which was the total duration of the study. The dose of 100 mg/L was sufficient to stabilise the tested wines. No differences in filterability were observed in comparison with MTA (metatartaric acid). The hypothesised protective effect against colour browning in white wines was not observed. Significance and impact of the study: The international wine trade requires stable wines. This paper provides information to support wineries in managing the use of KPA, as little information is available to date in the literature on this stabilising additive
The Lyman Alpha Reference Sample. VIII. Characterizing Lyman-Alpha Scattering in Nearby Galaxies
We examine the dust geometry and Ly{\alpha} scattering in the galaxies of the
Lyman Alpha Reference Sample (LARS), a set of 14 nearby (0.02 < < 0.2)
Ly{\alpha} emitting and starbursting systems with Hubble Space Telescope
Ly{\alpha}, H{\alpha}, and H{\beta} imaging. We find that the global dust
properties determined by line ratios are consistent with other studies, with
some of the LARS galaxies exhibiting clumpy dust media while others of them
show significantly lower Ly{\alpha} emission compared to their Balmer
decrement. With the LARS imaging, we present Ly{\alpha}/H{\alpha} and
H{\alpha}/H{\beta} maps with spatial resolutions as low as 40 pc, and
use these data to show that in most galaxies, the dust geometry is best modeled
by three distinct regions: a central core where dust acts as a screen, an
annulus where dust is distributed in clumps, and an outer envelope where
Ly{\alpha} photons only scatter. We show that the dust that affects the escape
of Ly{\alpha} is more restricted to the galaxies' central regions, while the
larger Ly{\alpha} halos are generated by scattering at large radii. We present
an empirical modeling technique to quantify how much Ly{\alpha} scatters in the
halo, and find that this "characteristic" scattering distance correlates with
the measured size of the Ly{\alpha} halo. We note that there exists a slight
anti-correlation between the scattering distance of Ly{\alpha} and global dust
properties.Comment: 32 pages, 51 figures, accepted to Ap
Phenotypic characterization of Adig null mice suggests roles for adipogenin in the regulation of fat mass accrual and leptin secretion
Adipogenin (Adig) is an adipocyte-enriched transmembrane protein. Its expression is induced during adipogenesis in rodent cells, and a recent genome-wide association study associated body mass index (BMI)-adjusted leptin levels with the ADIG locus. In order to begin to understand the biological function of Adig, we studied adipogenesis in Adig-deficient cultured adipocytes and phenotyped Adig null (Adig−/−) mice. Data from Adig-deficient cells suggest that Adig is required for adipogenesis. In vivo, Adig−/− mice are leaner than wild-type mice when fed a high-fat diet and when crossed with Ob/Ob hyperphagic mice. In addition to the impact on fat mass accrual, Adig deficiency also reduces fat-mass-adjusted plasma leptin levels and impairs leptin secretion from adipose explants, suggesting an additional impact on the regulation of leptin secretion
Comet Machholz (C/2004 Q2): morphological structures in the inner coma and rotation parameters
Extensive observations of comet C/2004 Q2 (Machholz) were carried out between
August 2004 and May 2005. The images obtained were used to investigate the
comet's inner coma features at resolutions between 350 and 1500 km/pixel. A
photometric analysis of the dust outflowing from the comet's nucleus and the
study of the motion of the morphological structures in the inner coma indicated
that the rotation period of the nucleus was most likely around 0.74 days. A
thorough investigation of the inner coma morphology allowed us to observe two
main active sources on the comet's nucleus, at a latitude of +85{\deg} \pm
5{\deg} and +45{\deg} \pm 5{\deg}, respectively. Further sources have been
observed, but their activity ran out quite rapidly over time; the most relevant
was at latcom. = 25{\deg} \pm 5{\deg}. Graphic simulations of the geometrical
conditions of observation of the inner coma were compared with the images and
used to determine a pole orientation at RA=95{\deg} \pm 5{\deg}, Dec=+35{\deg}
\pm 5{\deg}. The comet's spin axis was lying nearly on the plane of the sky
during the first decade of December 2004.Comment: 29 pages, 8 figures, 3 table
The Lyman Alpha Reference Sample IX: Revelations from deep surface photometry
The Lyman Alpha Reference Sample (LARS) of 14 star-forming galaxies offers a
wealth of insight into the workings of these local analogs to high-redshift
star-forming galaxies. The sample has been well-studied in terms of LyA and
other emission line properties, such as HI mass, gas kinematics, and
morphology. We analyze deep surface photometry of the LARS sample in UBIK
broadband imaging obtained at the Nordic Optical Telescope and the
Canada-France-Hawaii Telescope, and juxtaposition their derived properties with
a sample of local high-redshift galaxy analogs, namely, with blue compact
galaxies (BCGs). We construct radial surface brightness and color profiles with
both elliptical and isophotal integration, as well as RGB images, deep
contours, color maps, a burst fraction estimate, and a radial mass-to-light
ratio profile for each LARS galaxy. Standard morphological parameters like
asymmetry, clumpiness, the Gini and M20 coefficients are [...] analyzed, as
well as isophotal asymmetry profiles for each galaxy. [...] We compare the LARS
to the properties of the BCG sample and highlight the differences. Several
diagnostics indicate that the LARS galaxies have highly disturbed morphologies
even at the level of the faintest isophotes [...]. The ground-based photometry
[...] reveals previously unexplored isophotes [...]. The burst fraction
estimate suggests a spatially more extended burst region in LARS than in the
BCGs. [...] The galaxies in the LARS sample appear to be in earlier stages of a
merger event compared to the BCGs. Standard morphological diagnostics like
asymmetry, clumpiness, Gini and M20 coefficients cannot separate the two
samples, although an isophotal asymmetry profile successfully captures the
average difference in morphology. These morphological diagnostics do not show
any correlation with the equivalent width or the escape fraction of Lyman
Alpha. [abridged]Comment: 27 pages, 15 figures, accepted for publication in A&
Limits on the LyC signal from z~3 sources with secure redshift and HST coverage in the E-CDFS field
Aim: We aim to measure the LyC signal from a sample of sources in the Chandra
deep field south. We collect star-forming galaxies (SFGs) and active galactic
nuclei (AGN) with accurate spectroscopic redshifts, for which Hubble Space
Telescope (HST) coverage and multi-wavelength photometry are available. Method:
We selected a sample of about 200 sources at z~3. Taking advantage of HST
resolution, we applied a careful cleaning procedure and rejected sources
showing nearby clumps with different colours, which could be lower-z
interlopers. Our clean sample consisted of 86 SFGs (including 19 narrow-band
selected Lya emitters) and 8 AGN (including 6 detected in X-rays). We measured
the LyC flux from aperture photometry in four narrow-band filters covering
wavelengths below a 912 A rest frame (3.11<z<3.53). We estimated the ratio
between ionizing (LyC flux) and 1400 A non-ionizing emissions for AGN and
galaxies. Results: By running population synthesis models, we assume an average
intrinsic L(1400 A)/L(900 A) ratio of 5 as the representative value for our
sample. With this value and an average treatment of the lines of sight of the
inter-galactic medium, we estimate the LyC escape fraction relative to the
intrinsic value (fesc_rel(LyC)). We do not directly detect ionizing radiation
from any individual SFG, but we are able to set a 1(2)sigma upper limit of
fesc_rel(LyC)<12(24)%. This result is consistent with other non-detections
published in the literature. No meaningful limits can be calculated for the
sub-sample of Lya emitters. We obtain one significant direct detection for an
AGN at z=3.46, with fesc_rel(LyC) = (72+/-18)%. Conclusions: Our upper limit on
fescrel(LyC) implies that the SFGs studied here do not present either the
physical properties or the geometric conditions suitable for efficient
LyC-photon escape.Comment: Accepted for publication in A&A on Jan 5th, 201
Adipose-Derived Fatty Acid-Binding Proteins Plasma Concentrations Are Increased in Breast Cancer Patients.
BACKGROUND: Adipose tissue is an endocrine organ that could play a role in tumor progression via its secreted adipokines. The role of adipose-derived fatty acid-binding protein (FABP) 4 and FABP5 in breast cancer is presently under study, but their circulating levels in this pathology are poorly known. We analyzed the blood concentrations of FABP4 and FABP5 in breast cancer patients to determine whether there is an association between them and breast cancer. MATERIALS AND METHODS: We studied 294 women in the oncology department with a family history of breast cancer; 198 of the women had breast cancer, and 96 were healthy controls. The levels of FABP4, FABP5, lipid profile, standard biochemical parameter, and high-sensitivity C-reactive protein (hsCRP) were determined. We analyzed the association of FABP4 and FABP5 with breast cancer, while adjusting for demographic, anthropometric, and biochemical parameters. RESULTS: Breast cancer patients had a 24.8% (p < .0001) and 11.4% (p < .05) higher blood concentration of FABP4 and FABP5, respectively. Fatty acid-binding protein 4 was positively associated with age, body mass index (BMI), FABP5, very-low-density lipoprotein cholesterol (VLDLc), non-high-density lipoprote in cholesterol (non-HDLc), Apolipoprotein B 100 (ApoB100), triglycerides, glycerol, glucose, and hsCRP (p < .05), and was negatively associated with HDLc (p < .005) in breast cancer patients. Fatty acid-binding protein 5 was positively associated with BMI, FABP4, VLDLc, triglycerides, glycerol, and hsCRP (p < .05), and was negatively associated with HDLc and Apolipoprotein AI (ApoAI) (p < .05) in breast cancer patients. Using a logistic regression analysis and adjusting for age, BMI, hsCRP, non-HDLc, and triglycerides, FABP4 was independently associated with breast cancer (odds ratio [OR]: 1.091 [95% CI: 1.037-1.149]). Moreover, total cholesterol, VLDLc, non-HDLc, ApoB100, triglycerides, and hsCRP were significantly increased in breast cancer patients (p < .005). In contrast, the non-esterified fatty acids concentrations were significantly decreased in breast cancer patients (p < .05). CONCLUSION: Circulating FABP4 and FABP5 levels were increased in breast cancer patients compared with controls. The positive association of FABP4 with breast cancer was maintained after adjusting for important covariates, while the association with FABP5 was lost. Our data reinforce the role of adipose tissue and their adipokines in breast cancer. Despite these data, further studies must be performed to better explain the prognosis or diagnostic value of these blood parameters and their possible role in breast cancer. IMPLICATIONS FOR PRACTICE: We focus on the effect of adipose tissue on cancer, which is increasingly recognized. The association between adipocyte-derived adipokines and breast cancer opens new diagnosis and therapy perspectives. In this study, we provide original data concerning FABP4 and FABP5 plasma concentrations in breast cancer patients. Compared to control group, breast cancer patients show higher FABP4 and FABP5 blood levels. Our data suggest that, particularly, circulating FABP4 levels could be considered a new independent breast cancer biomarker. Our work translates basic science data to clinic linking the relationship between adipose tissue and lipid metabolism to breast cancer
TRACING the REIONIZATION EPOCH with ALMA: [C II] EMISSION in z ∼ 7 GALAXIES
We present new results on [CII]158 m emission from four galaxies in the
reionization epoch. These galaxies were previously confirmed to be at redshifts
between 6.6 and 7.15 from the presence of the Ly emission line in their
spectra. The Ly emission line is redshifted by 100-200 km/s compared to
the systemic redshift given by the [CII] line. These velocity offsets are
smaller than what is observed in z~3 Lyman break galaxies with similar UV
luminosities and emission line properties. Smaller velocity shifts reduce the
visibility of Ly and hence somewhat alleviate the need for a very
neutral IGM at z~7 to explain the drop in the fraction of Ly emitters
observed at this epoch.
The galaxies show [CII] emission with L[CII]=0.6-1.6 x10: these
luminosities place them consistently below the SFR-L[CII] relation observed for
low redshift star forming and metal poor galaxies and also below z =5.5 Lyman
break galaxies with similar star formation rates. We argue that previous
undetections of [CII] in z~7 galaxies with similar or smaller star formation
rates are due to selection effects: previous targets were mostly strong
Ly emitters and therefore probably metal poor systems, while our
galaxies are more representative of the general high redshift star forming
population .S.C. and R.M. acknowledge financial support from the Science and Technology Facilities Council (STFC).This is the author accepted manuscript. The final version is available from the Institute of Physics via http://dx.doi.org/10.3847/2041-8205/829/1/L1
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