1,240 research outputs found
An unexpected cause of pericardial effusion
We present a case of pericardial effusion due to embolization of a fragment of an inferior vena cava (IVC) filter, with subsequent perforation of the right ventricle. This is a rare and unexpected cause of pericardial effusion. Fracture or embolization of IVC filters is a relatively uncommon complication, but these events may have serious clinical implications. Although IVC filters are often placed with the intent of removal, the device in many patients is never removed. The long-term implications of IVC filter placement must be kept in mind when making decisions about device placement and subsequent removal
Comments on the nuclear symmetry energy
According to standard textbooks, the nuclear symmetry energy originates from
the {\it kinetic} energy and the {\it interaction} itself.
We argue that this view requires certain modifications.
We ascribe the physical origin of the {\it kinetic} term to the discreteness
of fermionic levels of, in principle arbitrary binary fermionic systems, and
relate its mean value directly to the average level density. Physically it
connects this part also to the isoscalar part of the interaction which, at
least in self-bound systems like atomic nuclei, decides upon the spatial
dimensions of the system. For the general case of binary fermionic systems
possible external confining potentials as well as specific boundary conditions
will contribute to this part. The reliability of this concept is tested using
self-consistent Skyrme Hartree-Fock calculations.Comment: 11 pages, 4 figure
Morphological and genetic diversity of the Balearic lizard,Podarcis lilfordi(Gunther, 1874): Is it relevant to its conservation?
Aims: To characterize the genetic and morphological diversification of the endangered Balearic lizard Podarcis lilfordi and to assess the relevance of this diversity, and how it is described, to conservation measures.
Location: This study covers all the populations of the Balearic lizard, Podarcis lilfordi, present in its range of distribution at coastal islets of Menorca, Mallorca and Cabrera Archipelago.
Methods: We analysed genetic and morphological variation across the 43 known extant populations of the Balearic lizard, using mitochondrial and nuclear markers. We examined morphometric and scalation characters using, in some cases, phylogenetically independent contrasts. We also incorporated the study of dorsal coloration and dorsal colour pattern including the analysis of melanism in several populations.
Results: We detected clear genetic divergence between Menorcan populations and populations from Mallorca and Cabrera, in both nuclear and mtDNA markers, but genetic divergence is relatively low among different insular populations within these groups. In contrast, morphological divergence was substantial both between Menorcan and remaining populations and within these groups. Morphological traits, such as dorsal coloration, body size and the number and size of scales, seemed to be linked with differences in climatic conditions between populations. In addition, some traits, as melanism, showed a strong phylogenetic signal.
Main conclusions: The morphological and genetic diversity of the Balearic lizard is incongruent with the subspecies described in the classical taxonomic literature. Moreover, current populations differ not only in some genetic and morphological features, but also in several ecological and ethological characteristics, in many cases unique to one population. Based on our results, we propose abandoning the use of subspecies to describe the extraordinary morphological diversity of the Balearic lizard and its replacement with the concept of evolutionary significant units (ESUs). ESUs are particularly suitable to describe and recognize such diversity and, especially, to ensure the continuity of the evolutionary process
Evolutionary history of Podarcis tiliguerta on Corsica and Sardinia.
BACKGROUND: Podarcis tiliguerta is a wall lizard endemic to the Mediterranean islands of Corsica and Sardinia. Previous findings of high mtDNA and morphological diversity have led to the suggestion that it may represent a species complex. Here, we analysed mitochondrial and nuclear markers (mtDNA, 3110Â bp; 6 nDNA loci, 3961Â bp) in P. tiliguerta sampled from thirty-two localities across Corsica and Sardinia. RESULTS: We find much greater intraspecific genetic divergence than between sister species of other Mediterranean island Podarcis, i.e., between P. lilfordi and P. pityusensis. We detected three mtDNA clusters in Corsica (North, South-East and South-West) and either two or three in Sardinia (North vs. South) depending on the clustering method. Only one or two nDNA groups were identified within each main island (again, depending on the method). A Bayesian time-calibrated multispecies coalescent tree was obtained from mtDNA and provided statistical support for a Miocene origin of the species (13.87Â Ma, 95% HPD: 18.30-10.77Â Ma). The posterior mean divergence time for the Corsican and Sardinian lineages was 12.75Â Ma ago (95% HPD: 16.94-9.04Â Ma). CONCLUSION: The results support the evolutionary distinctiveness of Corsican and Sardinian populations and also indicate a lack of post-divergence migration despite periods of contact being possible. Further to this, species delimitation analyses of Corsican and Sardinian lineages provided statistical support for their recognition as distinct (sister) taxa. Our results provide new insights into the biogeography of the Mediterranean biodiversity hotspot, and contribute important findings relevant to the systematics and evolution of this speciose lizard genus
Enhanced Pulse Propagation in Non-Linear Arrays of Oscillators
The propagation of a pulse in a nonlinear array of oscillators is influenced
by the nature of the array and by its coupling to a thermal environment. For
example, in some arrays a pulse can be speeded up while in others a pulse can
be slowed down by raising the temperature. We begin by showing that an energy
pulse (1D) or energy front (2D) travels more rapidly and remains more localized
over greater distances in an isolated array (microcanonical) of hard springs
than in a harmonic array or in a soft-springed array. Increasing the pulse
amplitude causes it to speed up in a hard chain, leaves the pulse speed
unchanged in a harmonic system, and slows down the pulse in a soft chain.
Connection of each site to a thermal environment (canonical) affects these
results very differently in each type of array. In a hard chain the dissipative
forces slow down the pulse while raising the temperature speeds it up. In a
soft chain the opposite occurs: the dissipative forces actually speed up the
pulse while raising the temperature slows it down. In a harmonic chain neither
dissipation nor temperature changes affect the pulse speed. These and other
results are explained on the basis of the frequency vs energy relations in the
various arrays
Genomic signatures of drift and selection driven by predation and human pressure in an insular lizard
Genomic divergence was studied in 10 small insular populations of the endangered Balearic Islands lizard (Podarcis lilfordi) using double digest restriction-site associated DNA sequencing. The objectives were to establish levels of divergence among populations, investigate the impact of population size on genetic variability and to evaluate the role of different environmental factors on local adaptation. Analyses of 72,846 SNPs supported a highly differentiated genetic structure, being the populations with the lowest population size (Porros, Foradada and Esclatasang islets) the most divergent, indicative of greater genetic drift. Outlier tests identified ~â2% of loci as candidates for selection. Genomic divergence-Enviroment Association analyses were performed using redundancy analyses based on SNPs putatively under selection, detecting predation and human pressure as the environmental variables with the greatest explanatory power. Geographical distributions of populations and environmental factors appear to be fundamental drivers of divergence. These results support the combined role of genetic drift and divergent selection in shaping the genetic structure of these endemic island lizard populations
Intestinal fungi contribute to development of alcoholic liver disease
This study was supported in part by NIH grants R01 AA020703, U01 AA021856 and by Award Number I01BX002213 from the Biomedical Laboratory Research & Development Service of the VA Office of Research and Development (to B.S.). K.H. was supported by a DFG (Deutsche Forschungsgemeinschaft) fellowship (HO/ 5690/1-1). S.B. was supported by a grant from the Swiss National Science Foundation (P2SKP3_158649). G.G. received funding from the Yale Liver Center NIH P30 DK34989 and R.B. from NIAAA grant U01 AA021908. A.K. received support from NIH grants RC2 AA019405, R01 AA020216 and R01 AA023417. G.D.B. is supported by funds from the Wellcome Trust. We acknowledge the Human Tissue and Cell Research (HTCR) Foundation for making human tissue available for research and Hepacult GmbH (Munich, Germany) for providing primary human hepatocytes for in vitro analyses. We thank Dr. Chien-Yu Lin Department of Medicine, Fu-Jen Catholic University, Taiwan for statistical analysis.Peer reviewedPublisher PD
New Physics and CP Violation in Hyperon Nonleptonic Decays
The sum of the CP-violating asymmetries A(Lambda_-^0) and A(Xi_-^-) in
hyperon nonleptonic decays is presently being measured by the E871 experiment.
We evaluate contributions to the asymmetries induced by chromomagnetic-penguin
operators, whose coefficients can be enhanced in certain models of new physics.
Incorporating recent information on the strong phases in Xi->Lambda pi decay,
we show that new-physics contributions to the two asymmetries can be
comparable. We explore how the upcoming results of E871 may constrain the
coefficients of the operators. We find that its preliminary measurement is
already better than the epsilon parameter of K-Kbar mixing in bounding the
parity-conserving contributions.Comment: 12 pages, 2 figure
The Subluminous Supernova 2007qd: A Missing Link in a Family of Low-Luminosity Type Ia Supernovae
We present multi-band photometry and multi-epoch spectroscopy of the peculiar
Type Ia supernova (SN Ia) 2007qd, discovered by the SDSS-II Supernova Survey.
It possesses physical properties intermediate to those of the peculiar SN
2002cx and the extremely low-luminosity SN 2008ha. Optical photometry indicates
that it had an extraordinarily fast rise time of <= 10 days and a peak absolute
B magnitude of -15.4 +/- 0.2 at most, making it one of the most subluminous SN
Ia ever observed. Follow-up spectroscopy of SN 2007qd near maximum brightness
unambiguously shows the presence of intermediate-mass elements which are likely
caused by carbon/oxygen nuclear burning. Near maximum brightness, SN 2007qd had
a photospheric velocity of only 2800 km/s, similar to that of SN 2008ha but
about 4000 and 7000 km/s less than that of SN 2002cx and normal SN Ia,
respectively. We show that the peak luminosities of SN 2002cx-like objects are
highly correlated with both their light-curve stretch and photospheric
velocities. Its strong apparent connection to other SN 2002cx-like events
suggests that SN 2007qd is also a pure deflagration of a white dwarf, although
other mechanisms cannot be ruled out. It may be a critical link between SN
2008ha and the other members of the SN 2002cx-like class of objects.Comment: To be published in the Astrophysical Journal; 37 pages, 13 figures, 4
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