523 research outputs found
New record of Egertonia (Elopiformes, Phyllodontidae) from the Late Cretaceous of South India
We report a new occurrence of the phyllodontid teleost fish Egertonia from the Late Cretaceous Kallamedu Formation of the Cauvery Basin, South India. This is the oldest occurrence of Phyllodontidae in India, and only the second Cretaceous Gondwanan occurrence of this genus, following a toothplate previously described from the Late Cretaceous Maevarano Formation, Madagascar. The presence of phyllodontid fish supports a fluvial-deltaic or brackish environment for the lower part of the Kallamedu Formation, a rich deposit including typically Gondwanan taxa, such as simosuchid crocodiles, bothremydid turtles and abelisaurid dinosaurs, as well as an anomalous troodontid dinosaur. Egertonia adds another taxon of primarily Laurasian distribution to the Kallamedu fauna and further expands the list of taxa known from the Late Cretaceous of both India and Madagascar, strengthening the degree of faunal similarity between the two landmasses in the latest Cretaceous
Acute renal failure due to severe rhabdomyolysis: a rare clinical manifestation of atrial myxoma
Gravitational collapse with tachyon field and barotropic fluid
A particular class of space-time, with a tachyon field, \phi, and a
barotropic fluid constituting the matter content, is considered herein as a
model for gravitational collapse. For simplicity, the tachyon potential is
assumed to be of inverse square form i.e., V(\phi) \sim \phi^{-2}. Our purpose,
by making use of the specific kinematical features of the tachyon, which are
rather different from a standard scalar field, is to establish the several
types of asymptotic behavior that our matter content induces. Employing a
dynamical system analysis, complemented by a thorough numerical study, we find
classical solutions corresponding to a naked singularity or a black hole
formation. In particular, there is a subset where the fluid and tachyon
participate in an interesting tracking behaviour, depending sensitively on the
initial conditions for the energy densities of the tachyon field and barotropic
fluid. Two other classes of solutions are present, corresponding respectively,
to either a tachyon or a barotropic fluid regime. Which of these emerges as
dominant, will depend on the choice of the barotropic parameter, \gamma.
Furthermore, these collapsing scenarios both have as final state the formation
of a black hole.Comment: 18 pages, 7 figures. v3: minor changes. Final version to appear in
GR
Ballistic Josephson junctions in edge-contacted graphene
Hybrid graphene-superconductor devices have attracted much attention since
the early days of graphene research. So far, these studies have been limited to
the case of diffusive transport through graphene with poorly defined and modest
quality graphene-superconductor interfaces, usually combined with small
critical magnetic fields of the superconducting electrodes. Here we report
graphene based Josephson junctions with one-dimensional edge contacts of
Molybdenum Rhenium. The contacts exhibit a well defined, transparent interface
to the graphene, have a critical magnetic field of 8 Tesla at 4 Kelvin and the
graphene has a high quality due to its encapsulation in hexagonal boron
nitride. This allows us to study and exploit graphene Josephson junctions in a
new regime, characterized by ballistic transport. We find that the critical
current oscillates with the carrier density due to phase coherent interference
of the electrons and holes that carry the supercurrent caused by the formation
of a Fabry-P\'{e}rot cavity. Furthermore, relatively large supercurrents are
observed over unprecedented long distances of up to 1.5 m. Finally, in the
quantum Hall regime we observe broken symmetry states while the contacts remain
superconducting. These achievements open up new avenues to exploit the Dirac
nature of graphene in interaction with the superconducting state.Comment: Updated version after peer review. Includes supplementary material
and ancillary file with source code for tight binding simulation
Effect of vitamin D supplementation on bone health parameters of healthy young Indian women
Summary There is a huge prevalence of hypovitaminosis D in the Indian population. We studied the efficacy and safety of oral vitamin D supplementation in apparently healthy adult women. Monthly cholecalciferol given orally, 60,000 IU/month during summers and 120,000 IU/month during winters, safely increases 25-hydroxyvitamin D (25 (OH)D) levels to near normal levels. Introduction There is a huge burden of hypovitaminosis D in the Indian population. The current recommendation for vitamin D supplementation is not supported by sufficient evidence. Methods Study subjects included 100 healthy adult women of reproductive age group from hospital staff. They wer
Microfinance, Financial Literacy, and Household Power Configuration in Rural Bangladesh: An Empirical Study on Some Credit Borrowers
Regional differentiation of felid vertebral column evolution: a study of 3D shape trajectories
Recent advances in geometric morphometrics provide improved techniques for extraction of biological information from shape and have greatly contributed to the study of ecomorphology and morphological evolution. However, the vertebral column remains an under-studied structure due in part to a concentration on skull and limb research, but most importantly because of the difficulties in analysing the shape of a structure composed of multiple articulating discrete units (i.e. vertebrae). Here, we have applied a variety of geometric morphometric analyses to three-dimensional landmarks collected on 19 presacral vertebrae to investigate the influence of potential ecological and functional drivers, such as size, locomotion and prey size specialisation, on regional morphology of the vertebral column in the mammalian family Felidae. In particular, we have here provided a novel application of a method—phenotypic trajectory analysis (PTA)—that allows for shape analysis of a contiguous sequence of vertebrae as functionally linked osteological structures. Our results showed that ecological factors influence the shape of the vertebral column heterogeneously and that distinct vertebral sections may be under different selection pressures. While anterior presacral vertebrae may either have evolved under stronger phylogenetic constraints or are ecologically conservative, posterior presacral vertebrae, specifically in the post-T10 region, show significant differentiation among ecomorphs. Additionally, our PTA results demonstrated that functional vertebral regions differ among felid ecomorphs mainly in the relative covariation of vertebral shape variables (i.e. direction of trajectories, rather than in trajectory size) and, therefore, that ecological divergence among felid species is reflected by morphological changes in vertebral column shape
A Comparative Study of the Effect of Non-Antibiotic Feed Additives on Experimental Colonization of Salmonella Enterica Serovar Enteridis and Intestinal Pathomorphology in Broiler Chickens
ABSTRACT The objective of this study was to evaluate the effect of eubiotics on the intestinal morphology of broilers. For this purpose, 125 birds were divided into six groups with two replicates each (10 birds in each replicate). Group A was given a Basal diet. All groups except group A were challenged with Salmonella enterica serovar Enteritidis. Group B was provided the basal diet, group C was fed a Probiotic-added diet; group D was fed a Prebiotics-based diet; group E was given essential oils plus the basal diet; and group F was provided with organic acids plus the basal diet. Two separate experiments were carried out for Salmonella recovery, checking the cecal tonsils and conducting an intestinal pathomorphic evaluation. Villus length, villus width, villus surface area, and crypt depth were measured by micrometry. There was an overall improvement (p<0.05) in intestinal morphometric parameters for all the treatment groups except for the negative control group, which showed the lowest villus height and villus depth values. Maximum villus height (p<0.05) of the duodenum was achieved by group E, which was fed a diet containing essential oils, whereas a maximum villus surface area index (p<0.05) was recorded for the birds of Group D, which were fed a diet containing prebiotics. Maximum villus height (p<0.05) and surface area index in ileum mucosa was recorded (p<0.05) in the birds of group D (treated with prebiotics). It is concluded that there is an overall increase in the gut histology of broilers fed non-antibiotic based feed
Ecomorphology of Carnivora challenges convergent evolution
Convergent evolution is often reported in the mammalian order Carnivora. Their adaptations to particularly demanding feeding habits such as hypercarnivory and durophagy (consumption of tough food) appear to favour morphological similarities between distantly related species, especially in the skull. However, phylogenetic effect in phenotypic data might obscure such a pattern. We first validated the hypotheses that extant hypercarnivorous and durophagous large carnivorans converge in mandibular shape and form (size and shape). Hypercarnivores generally exhibit smaller volumes of the multidimensional shape and form space than their sister taxa, but this pattern is significantly different from random expectation only when hunting behaviour categorisations are taken into account. Durophages share areas of the morphospace, but this seems to be due to factors of contingency. Carnivorans that hunt in pack exhibit incomplete convergence while even stronger similarities occur in the mandible shape of solitary hunters due to the high functional demands in killing the prey. We identified a stronger phylogenetic signal in mandibular shape than in size. The quantification of evolutionary rates of changes suggests that mandible shape of solitary hunters evolved slowly when compared with other carnivorans. These results consistently indicate that the need for a strong bite force and robust mandible override sheer phylogenetic effect in solitary hunters
The Formation of the First Massive Black Holes
Supermassive black holes (SMBHs) are common in local galactic nuclei, and
SMBHs as massive as several billion solar masses already exist at redshift z=6.
These earliest SMBHs may grow by the combination of radiation-pressure-limited
accretion and mergers of stellar-mass seed BHs, left behind by the first
generation of metal-free stars, or may be formed by more rapid direct collapse
of gas in rare special environments where dense gas can accumulate without
first fragmenting into stars. This chapter offers a review of these two
competing scenarios, as well as some more exotic alternative ideas. It also
briefly discusses how the different models may be distinguished in the future
by observations with JWST, (e)LISA and other instruments.Comment: 47 pages with 306 references; this review is a chapter in "The First
Galaxies - Theoretical Predictions and Observational Clues", Springer
Astrophysics and Space Science Library, Eds. T. Wiklind, V. Bromm & B.
Mobasher, in pres
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