555 research outputs found
Assessment of hydrocarbon pollution in NW Iberian Peninsula using bioaccumulation and molecular biomarkers in Mytilus galloprovincialis
Society of Environmental Toxicology and Chemistry - SETAC Europe 15th Annual Meeting, Lille, France, May 2005.Polycyclic aromatic hydrocarbons (PAH´s) are ubiquitous contaminants in marine environment as a result of uncontrolled spills, river transport, surface runoff and atmospheric deposition. A significant amount of industrial activity including shipping and oil refining is located along the NW Iberian Peninsula coast. The use of exposure biomarkers holds out promise due to the incipient state of the cost-effective methodologies for diagnosis and monitoring of oil pollution. This work presents the preliminary results concerning the identification of a set of biomarkers for an early warning detection of PAH toxicity. The bivalve Mytillus galloprovincialis was selected due to its ubiquitous distribution along coastline, being used as sentinels in pollution monitoring. This species has also an important value. Four locations in the vicinity of industrial wastewater discharges along the NW Iberian coast were selected and compared with a nearby (reference) site for (i) measurements of PAH body burdens and (ii) levels of enzyme activity: catalase (CAT), superoxide-dismutase (SOD), glutathione peroxidase (GPx), gluthathione S-transferase (GST) and Na+/K+ATPase (ATPase). The results will be discussed on the basis of their potential in providing additional evidence for discriminate between well known polluted and unpolluted sites
Isotopic liftings of Clifford algebras and applications in elementary particle mass matrices
Isotopic liftings of algebraic structures are investigated in the context of
Clifford algebras, where it is defined a new product involving an arbitrary,
but fixed, element of the Clifford algebra. This element acts as the unit with
respect to the introduced product, and is called isounit. We construct
isotopies in both associative and non-associative arbitrary algebras, and
examples of these constructions are exhibited using Clifford algebras, which
although associative, can generate the octonionic, non-associative, algebra.
The whole formalism is developed in a Clifford algebraic arena, giving also the
necessary pre-requisites to introduce isotopies of the exterior algebra. The
flavor hadronic symmetry of the six u,d,s,c,b,t quarks is shown to be exact,
when the generators of the isotopic Lie algebra su(6) are constructed, and the
unit of the isotopic Clifford algebra is shown to be a function of the six
quark masses. The limits constraining the parameters, that are entries of the
representation of the isounit in the isotopic group SU(6), are based on the
most recent limits imposed on quark masses.Comment: 19 page
PIN14 COST-EFFECTIVENESS OF LINEZOLID VERSUS VANCOMYCIN IN THE TREATMENT OF NOSOCOMIAL PNEUMONIA SUSPECTED TO BE CAUSED BY METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS IN SPAIN
Very special relativity as relativity of dark matter: the Elko connection
In the very special relativity (VSR) proposal by Cohen and Glashow, it was
pointed out that invariance under HOM(2) is both necessary and sufficient to
explain the null result of the Michelson-Morely experiment. It is the quantum
field theoretic demand of locality, or the requirement of P, T, CP, or CT
invariance, that makes invariance under the Lorentz group a necessity.
Originally it was conjectured that VSR operates at the Planck scale; we propose
that the natural arena for VSR is at energies similar to the standard model,
but in the dark sector. To this end we provide an ab initio spinor
representation invariant under the SIM(2) avatar of VSR and construct a mass
dimension one fermionic quantum field of spin one half. This field turns out to
be a very close sibling of Elko and it exhibits the same striking property of
intrinsic darkness with respect to the standard model fields. In the new
construct, the tension between Elko and Lorentz symmetries is fully resolved.
We thus entertain the possibility that the symmetries underlying the standard
model matter and gauge fields are those of Lorentz, while the event space
underlying the dark matter and the dark gauge fields supports the algebraic
structure underlying VSR.Comment: 19 pages. Section 5 is new. Published version (modulo a footnote, and
a corrected typo
The Metallicity Distribution Functions of SEGUE G and K dwarfs: Constraints for Disk Chemical Evolution and Formation
We present the metallicity distribution function (MDF) for 24,270 G and
16,847 K dwarfs at distances from 0.2 to 2.3 kpc from the Galactic plane, based
on spectroscopy from the Sloan Extension for Galactic Understanding and
Exploration (SEGUE) survey. This stellar sample is significantly larger in both
number and volume than previous spectroscopic analyses, which were limited to
the solar vicinity, making it ideal for comparison with local volume-limited
samples and Galactic models. For the first time, we have corrected the MDF for
the various observational biases introduced by the SEGUE target selection
strategy. The SEGUE sample is particularly notable for K dwarfs, which are too
faint to examine spectroscopically far from the solar neighborhood. The MDF of
both spectral types becomes more metal-poor with increasing |Z|, which reflects
the transition from a sample with small [alpha/Fe] values at small heights to
one with enhanced [alpha/Fe] above 1 kpc. Comparison of our SEGUE distributions
to those of two different Milky Way models reveals that both are more
metal-rich than our observed distributions at all heights above the plane. Our
unbiased observations of G and K dwarfs provide valuable constraints over the
|Z|-height range of the Milky Way disk for chemical and dynamical Galaxy
evolution models, previously only calibrated to the solar neighborhood, with
particular utility for thin- and thick-disk formation models.Comment: 70 pages, 25 figures, 7 tables. Accepted by The Astrophysical Journa
Association between adiposity levels and cognitive impairment in the Chilean older adult population
Although both obesity and ageing are risk factors for cognitive impairment, there is no evidence in Chile on how obesity levels are associated with cognitive function. Therefore, the aim of the present study was to investigate the association between adiposity levels and cognitive impairment in older Chilean adults. This cross-sectional study includes 1384 participants, over 60 years of age, from the Chilean National Health Survey 2009–2010. Cognitive impairment was evaluated using the Mini-Mental State Examination. BMI and waist circumference (WC) were used as measures of adiposity. Compared with people with a normal BMI, the odds of cognitive impairment were higher in participants who were underweight (OR 4·44; 95 % CI 2·43, 6·45; P < 0·0001), overweight (OR 1·86; 95 % CI 1·06, 2·66; P = 0·031) and obese (OR 2·26; 95 % CI 1·31, 3·21; P = 0·003). The associations were robust after adjustment for confounding variables. Similar results were observed for WC. Low and high levels of adiposity are associated with an increased likelihood of cognitive impairment in older adults in Chile
Two Notch Ligands, Dll1 and Jag1, Are Differently Restricted in Their Range of Action to Control Neurogenesis in the Mammalian Spinal Cord
Notch signalling regulates neuronal differentiation in the vertebrate nervous system. In addition to a widespread function in maintaining neural progenitors, Notch signalling has also been involved in specific neuronal fate decisions. These functions are likely mediated by distinct Notch ligands, which show restricted expression patterns in the developing nervous system. Two ligands, in particular, are expressed in non-overlapping complementary domains of the embryonic spinal cord, with Jag1 being restricted to the V1 and dI6 progenitor domains, while Dll1 is expressed in the remaining domains. However, the specific contribution of different ligands to regulate neurogenesis in vertebrate embryos is still poorly understood.In this work, we investigated the role of Jag1 and Dll1 during spinal cord neurogenesis, using conditional knockout mice where the two genes are deleted in the neuroepithelium, singly or in combination. Our analysis showed that Jag1 deletion leads to a modest increase in V1 interneurons, while dI6 neurogenesis was unaltered. This mild Jag1 phenotype contrasts with the strong neurogenic phenotype detected in Dll1 mutants and led us to hypothesize that neighbouring Dll1-expressing cells signal to V1 and dI6 progenitors and restore neurogenesis in the absence of Jag1. Analysis of double Dll1;Jag1 mutant embryos revealed a stronger increase in V1-derived interneurons and overproduction of dI6 interneurons. In the presence of a functional Dll1 allele, V1 neurogenesis is restored to the levels detected in single Jag1 mutants, while dI6 neurogenesis returns to normal, thereby confirming that Dll1-mediated signalling compensates for Jag1 deletion in V1 and dI6 domains.Our results reveal that Dll1 and Jag1 are functionally equivalent in controlling the rate of neurogenesis within their expression domains. However, Jag1 can only activate Notch signalling within the V1 and dI6 domains, whereas Dll1 can signal to neural progenitors both inside and outside its domains of expression
Measurement of χ c1 and χ c2 production with s√ = 7 TeV pp collisions at ATLAS
The prompt and non-prompt production cross-sections for the χ c1 and χ c2 charmonium states are measured in pp collisions at s√ = 7 TeV with the ATLAS detector at the LHC using 4.5 fb−1 of integrated luminosity. The χ c states are reconstructed through the radiative decay χ c → J/ψγ (with J/ψ → μ + μ −) where photons are reconstructed from γ → e + e − conversions. The production rate of the χ c2 state relative to the χ c1 state is measured for prompt and non-prompt χ c as a function of J/ψ transverse momentum. The prompt χ c cross-sections are combined with existing measurements of prompt J/ψ production to derive the fraction of prompt J/ψ produced in feed-down from χ c decays. The fractions of χ c1 and χ c2 produced in b-hadron decays are also measured
Single hadron response measurement and calorimeter jet energy scale uncertainty with the ATLAS detector at the LHC
The uncertainty on the calorimeter energy response to jets of particles is
derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the
calorimeter response to single isolated charged hadrons is measured and
compared to the Monte Carlo simulation using proton-proton collisions at
centre-of-mass energies of sqrt(s) = 900 GeV and 7 TeV collected during 2009
and 2010. Then, using the decay of K_s and Lambda particles, the calorimeter
response to specific types of particles (positively and negatively charged
pions, protons, and anti-protons) is measured and compared to the Monte Carlo
predictions. Finally, the jet energy scale uncertainty is determined by
propagating the response uncertainty for single charged and neutral particles
to jets. The response uncertainty is 2-5% for central isolated hadrons and 1-3%
for the final calorimeter jet energy scale.Comment: 24 pages plus author list (36 pages total), 23 figures, 1 table,
submitted to European Physical Journal
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