6,680 research outputs found
The Friedmann-Lemaitre-Robertson-Walker Big Bang singularities are well behaved
We show that the Big Bang singularity of the
Friedmann-Lemaitre-Robertson-Walker model does not raise major problems to
General Relativity. We prove a theorem showing that the Einstein equation can
be written in a non-singular form, which allows the extension of the spacetime
before the Big Bang. The physical interpretation of the fields used is
discussed. These results follow from our research on singular semi-Riemannian
geometry and singular General Relativity.Comment: 10 pages, 5 figure
Production, purification and characterization of two recombinant DNA-derived N-terminal ovine growth hormone variants: oGH3 and oGH5
Two recombinant DNA-derived variants of ovine growth hormone were produced, purified, characterized and compared with the authentic pituitary derived GH. The variants oGH3 and oGH5 were isolated by differential centrifugation method and were purified after refolding by ion-exchangechromatography and gel filtration. Both the proteins showed single band on SDS-PAGE and had molecular weight and iso-electric point closer to authentic pituitary GH. The variants oGH3 and oGH5 were compared with the authentic pituitary derived GH in radio immuno assays, radio receptor assays and binding with the monoclonal antibodies OA 11 and OA12
Hepatitis C virus-associated porphyria cutanea tarda: A case report
Porhyria cutanea tarda (PCT) is a rare, inherited or acquired disorder due to decreased activity or deficiency of uroporphyrinogen decarboxylase (UROD), one of the enzymes in the haem synthetic pathway. It is characterized by cutaneous manifestations such as erosions, blisters and bulae in the dorsum of the hand, forearm, elbows and knees; and painful indolent sores that heal with dyspigmented and scarring lesions. A 25 year old sales man presented with a 7 month history of recurrent blistering of the skin of the extremities- hands, elbows, knees and feet which occurred spontaneously or following trivial trauma. There was no family history of similar skin symptoms. Examination showed broken and fresh blisters of varying sizes with some healed lesions on the dorsum of the hands, over the elbow and knee joints, and toes. Serum ferritin was 360Ό/L (40- 340 Ό/L), urine uroporphyrinogen was positive (+++) and Hepatitis C antibodies screening was positive. Some improvement of the cutaneous lesion was noticed following commencement of therapeutic phlebotomy.Keywords: Porhyria, blisters, Hepatitis C virus, uroporphyrinoge
The holistic phase model of early adult crisis
The objective of the current study was to explore the structural, temporal and experiential manifestations of crisis episodes in early adulthood, using a holistic-systemic theoretical framework. Based on an analysis of 50 interviews with individuals about a crisis episode between the ages of 25 and 35, a holistic model was developed. The model comprises four phases: (1) Locked-in, (2) Separation/Time-out, (3) Exploration and (4) Rebuilding, which in turn have characteristic features at four levelsâperson-in-environment, identity, motivation and affect-cognition. A crisis starts out with a commitment at work or home that has been made but is no longer desired, and this is followed by an emotionally volatile period of change as that commitment is terminated. The positive trajectory of crisis involves movement through an exploratory period towards active rebuilding of a new commitment, but âfast-forwardâ and ârelapseâ loops can interrupt Phases 3 and 4 and make a positive resolution of the episode less likely. The model shows conceptual links with life stage theories of emerging adulthood and early adulthood, and it extends current understandings of the transitional developmental challenges that young adults encounter
XFEM formulation with sub-interpolation, and equivalence to zero-thickness interface elements
This is the accepted version of the following article: Crusat L, Carol I, Garolera D. XFEM formulation with subâinterpolation, and equivalence to zeroâthickness interface elements. Int J Numer Anal Methods Geomech. 2019;43:45â76. https://doi.org/10.1002/nag.2853, which has been published in final form at https://doi.org/10.1002/nag.2853This paper describes a particular formulation of the extended finite element method (XFEM) specifically conceived for application to existing discontinuities of fixed location, for instance, in geological media. The formulation is based on two nonstandard assumptions: (1) the use of sub-interpolation functions for each subdomain and (2) the use of fictitious displacement variables on the nodes across the discontinuity (instead of the more traditional jump variables). Thanks to the first of those assumptions, the proposed XFEM formulation may be shown to be equivalent to the standard finite element method with zero-thickness interface elements for the discontinuities (FEM+z). The said equivalence is theoretically proven for the case of quadrangular elements cut in two quadrangles by the discontinuity, and only approximate for other types of intersections of quadrangular or triangular elements, in which the XFEM formulation corresponds to a kinematically restricted version of the corresponding interface plus continuum scheme. The proposed XFEM formulation with sub-interpolation, also helps improving spurious oscillations of the results obtained with natural interpolation functions when the discontinuity runs skew to the mesh. A possible explanation for these oscillations is provided, which also explains the improvement observed with sub-interpolation. The paper also discusses the oscillations observed in the numerical results when some nodes are too close to the discontinuity and proposes the remedy of moving those nodes onto the discontinuity itself. All the aspects discussed are illustrated with some examples of application, the results of which are compared with closed-form analytical solutions or to existing XFEM results from the literature.Peer ReviewedPostprint (author's final draft
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Section of the corpus callosum in kainic acid induced seizures in rats: behavioral, electroencephalographic and neuropathological study.
Clinical and experimental data suggest that the role of corpus callosum in epilepsy includes synchronization, spread, excitation and inhibition. Section of the corpus callosum (SCC) is known to be a useful therapy in selected types of generalized epilepsy, i.e., tonic, atonic and generalized convulsive seizures, but not partial seizures which may be exacerbated by this procedure. The goal of this study was to determine the effect of SCC in the kainic acid (KA) model of limbic seizures in rats. Using several doses of KA (2.5, 5 and 10 mg/kg) injected systemically, we found a potentiation of the behavioral, electrographic and histological effects of KA in the SCC group of animals compared to the sham-operated control rats. A low dose of kainic acid (2.5 and 5 mg/kg) induced status epilepticus in the SCC animals, but not in the sham-operated control rats. These data demonstrate that in the KA model of temporal lobe seizures, SCC not only fails to protect, but actually intensifies seizures. This finding is compatible with the hypothesis that there is an inhibitory influence, via the corpus callosum, of the non epileptic neocortex on its contralateral homologue in the kainic acid model
Gastrointestinal parasitism in local and exotic breeds of chickens reared in Gwagwalada Guinea Savannah zone of Nigeria
The present study was carried out to establish the gastrointestinal parasites in local and exotic breeds of chickens reared in Gwagwalada, Guinea Savannah Zone of Nigeria. It was conducted between July and September, 2014. Two hundred and eighty (280) faecal samples from local and exotic breeds of chicken and 50 intact whole intestines were collected randomly from seven (7) major towns (Gwagwalada, Dobi, Gwako, Giri, Anagada, Tungan Maje and Zuba) in Gwagwalada Area council and examined for gastrointestinal parasites using flotation and sedimentation methods. Six (6) different gastrointestinal parasite eggs and oocytes were identified in 42.5% of the birds examined. Of these parasites, Ascaridia species was found to be the most prevalent (36.1%) among the chickens. Other parasites encountered include; Eimeria oocytes (34.5%), Heterakis species (12.6%), Rallietina species 10.1%; Capillaria species (4.2%) and Syngamus species (2.5%). There were mixed infection of 1.4% among the infected birds. Interestingly, none of the birds examined was infected with trematodes There was no significant difference (p>0.05) in prevalence rate of infection between the local and exotic breeds of chickens. Although males had a higher prevalence of infection than the females in both breeds, there was no significant difference (p>0.05) in the prevalence of infection among sexes. However, there was significant difference (P<0.05) between the age groups, with highest infection occuring in growers (46.2%). 20 (40%) of the 50 intact whole intestines screened were positive for gastrointestinal parasites by gross examination of intestinal tract. Out of the 20 positive, 12 were nematodes, 3 cestodes and remaining 5 were mixed infections. Therefore, sustainable ways of controlling these parasites at a particular age and further studies on the prevalence of gastrointestinal parasites in chicken need to be elucidated for improved intensive egg and poultry meat productionsKeywords: Chickens, Exotic, Gastrointestinal, Local, Parasites, Prevalenc
Large-scale diversity estimation through surname origin inference
The study of surnames as both linguistic and geographical markers of the past
has proven valuable in several research fields spanning from biology and
genetics to demography and social mobility. This article builds upon the
existing literature to conceive and develop a surname origin classifier based
on a data-driven typology. This enables us to explore a methodology to describe
large-scale estimates of the relative diversity of social groups, especially
when such data is scarcely available. We subsequently analyze the
representativeness of surname origins for 15 socio-professional groups in
France
Expanded polyfunctional T cell response to mycobacterial antigens in TB disease and contraction post-treatment.
BACKGROUND: T cells producing multiple factors have been shown to be required for protection from disease progression in HIV but we have recently shown this not to be the case in TB. Subjects with active disease had a greater proportion of polyfunctional cells responding to ESAT-6/CFP-10 stimulation than their infected but non-diseased household contacts (HHC). We therefore wanted to assess this profile in subjects who had successfully completed standard TB chemotherapy. METHODS: We performed a cross-sectional study using PBMC from TB cases (pre- and post-treatment) and HHC. Samples were stimulated overnight with TB antigens (ESAT-6/CFP-10 and PPD) and their CD4+ and CD8+ T cells were assessed for production of CD107a, IFN-gamma, IL-2 and TNF-alpha and the complexity of the responses was determined using SPICE and PESTLE software. RESULTS AND CONCLUSIONS: We found that an increase in complexity (i.e., production of more than 1 factor simultaneously) of the T cell profile was associated with TB disease and that this was significantly reduced following TB treatment. This implies that T cells are able to respond adequately to TB antigens with active disease (at least initially) but the ability of this response to protect the host from disease progression is hampered, presumably due to immune evasion strategies by the bacteria. These findings have implications for the development of new diagnostics and vaccine strategies
Delta-9-tetrahydrocannabinol protects against MPP+ toxicity in SH-SY5Y cells by restoring proteins involved in mitochondrial biogenesis
This project was supported through a studentship awarded by the Plymouth University Peninsula Schools of Medicine and Dentistry.Proliferator-activated receptor Îł (PPARÎł) activation can result in transcription of proteins involved in oxidative stress defence and mitochondrial biogenesis which could rescue mitochondrial dysfunction in Parkinson's disease (PD).The PPARÎł agonist pioglitazone is protective in models of PD; however side effects have limited its clinical use. The cannabinoid Î9-tetrahydrocannabinol (Î9-THC) may have PPARÎł dependent anti-oxidant properties. Here we investigate the effects of Î9-THC and pioglitazone on mitochondrial biogenesis and oxidative stress. Differentiated SH-SY5Y neuroblastoma cells were exposed to the PD relevant mitochondrial complex 1 inhibitor 1-methyl- 4-phenylpyridinium iodide (MPP+). We found that only Î9-THC was able to restore mitochondrial content in MPP+ treated SH-SY5Y cells in a PPARÎł dependent manner by increasing expression of the PPARÎł co-activator 1a (PGC-1a), the mitochondrial transcription factor (TFAM) as well as mitochondrial DNA content. Co-application of Î9- THC with pioglitazone further increased the neuroprotection against MPP+ toxicity as compared to pioglitazone treatment alone. Furthermore, using lentiviral knock down of the PPARÎł receptor we showed that, unlike pioglitazone, Î9-THC resulted in a PPARÎł dependent reduction of MPP+ induced oxidative stress. We therefore suggest that, in contrast to pioglitazone, Î9-THC mediates neuroprotection via PPARÎł-dependent restoration of mitochondrial content which may be beneficial for PD treatment.Publisher PDFPeer reviewe
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