2,358 research outputs found

    On the Cretaceous origin of the Order Syracosphaerales and the genus Syracosphaera

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    New scanning electron microscope observations of unadulterated calcareous nannofossil assemblages on lamina surfaces of Cretaceous Tanzania Drilling Project sediments reveal high diversity in the < 3 μm size-range and high abundances of small and frangible morphologies. These assemblages prompt comparison to modern assemblages, which show similar high diversity and abundance of very small and fragile taxa, although these assemblages are generally not preserved in the fossil record due to taphonomic filtering. Not only are there broad similarities between the general composition of modern assemblages and those of the Tanzanian lagerstätte, but also our discovery of several new Cretaceous taxa provides evidence for greatly extended fossil lineages of extant orders, with implications for both deep-time biodiversity divergence and survival through the end-Cretaceous mass extinction. Our findings include: new species that are the first-recorded Mesozoic representatives of the extant Syracosphaeraceae and Papposphaeraceae; potentially previously unrecorded diversity in the Mesozoic Calciosoleniaceae, another extant order, represented by extant species that have been described already; and new species and unusually high abundances of the Mesozoic Stephanolithiaceae. We also highlight the extended range of an incertae sedis Cenozoic genus, Ellipsolithus, into at least the Turonian. Here, we describe seven new miniscule to very small Cretaceous species: Syracosphaera antiqua, S. repagula, Pocillithus macleodii, P. crucifer, Stradnerlithus wendleri, S.? haynesiae and Tortolithus foramen

    Obesity and cage environment modulate metabolism in the Zucker rat: a multiple biological matrix approach to characterizing metabolic phenomena

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    Obesity and its comorbidities are increasing worldwide imposing a heavy socioeconomic burden. The effects of obesity on the metabolic profiles of tissues (liver, kidney, pancreas), urine, and the systemic circulation were investigated in the Zucker rat model using 1H NMR spectroscopy coupled to multivariate statistical analysis. The metabolic profiles of the obese ( fa/ fa) animals were clearly differentiated from the two phenotypically lean phenotypes, ((+/+) and ( fa/+)) within each biological compartment studied, and across all matrices combined. No significant differences were observed between the metabolic profiles of the genotypically distinct lean strains. Obese Zucker rats were characterized by higher relative concentrations of blood lipid species, cross-compartmental amino acids (particularly BCAAs), urinary and liver metabolites relating to the TCA cycle and glucose metabolism; and lower amounts of urinary gut microbial-host cometabolites, and intermatrix metabolites associated with creatine metabolism. Further to this, the obese Zucker rat metabotype was defined by significant metabolic alterations relating to disruptions in the metabolism of choline across all compartments analyzed. The cage environment was found to have a significant effect on urinary metabolites related to gut-microbial metabolism, with additional cage-microenvironment trends also observed in liver, kidney, and pancreas. This study emphasizes the value in metabotyping multiple biological matrices simultaneously to gain a better understanding of systemic perturbations in metabolism, and also underscores the need for control or evaluation of cage environment when designing and interpreting data from metabonomic studies in animal models

    Systemic Characterization of an Obese Phenotype in the Zucker Rat Model Defining Metabolic Axes of Energy Metab-olism and Host-Microbial Interactions

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    The Zucker (fa/fa) rat is a valuable and extensively utilized model for obesity research. However, the metabolic networks underlying the systemic response in the obese Zucker rats remain to be elucidated. This information is important to further our understanding of the circulation of the microbial or host–microbial metabolites and their impact on host metabolism. 1H nuclear magnetic resonance spectroscopy-based metabolic profiling was used to probe global metabolic differences in portal vein and peripheral blood plasma, urine and fecal water between obese (fa/fa, n = 12) and lean (fa/+, n = 12) Zucker rats. Urinary concentrations of host–microbial co-metabolites were found to be significantly higher in lean Zucker rats. Higher concentrations of fecal lactate, short chain fatty acids (SCFAs), 3-hydroxyphenyl propionic acid and glycerol, and lower levels of valine and glycine were observed in obese rats compared with lean animals. Regardless of phenotype, concentrations of SCFAs, tricarboxylic acid cycle intermediates, and choline metabolites were higher in portal vein blood compared to peripheral blood. However, higher levels of succinate, phenylalanine and tyrosine were observed in portal vein blood compared with peripheral blood from lean rats but not in obese rats. Our findings indicate that the absorption of propionate, acetate, choline, and trimethylamine is independent of the Zucker rat phenotypes. However, urinary host–microbial co-metabolites were highly associated with phenotypes, suggesting distinct gut microbial metabolic activities in lean and obese Zucker rats. This work advances our understanding of metabolic processes associated with obesity, particularly the metabolic functionality of the gut microbiota in the context of obesity

    Magnetization hysteresis and time decay measurements in FeSe0.50_{0.50}Te0.50_{0.50} : Evidence for fluctuation in mean free path induced pinning

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    We present results of magnetic measurements relating to vortex phase diagram in a single crystal of FeSe0.5_{0.5}Te0.5_{0.5} which displays second magnetization peak anomaly for H∥cH \parallel c. The possible role of the crystalline anisotropy on vortex pinning is explored via magnetic torque magnetometry. We present evidence in favor of pinning related to spatial variations of the charge carrier mean free path leading to small bundle vortex pinning by randomly distributed (weak) pinning centers for both H∥cH \parallel c and H⊥cH \perp c. This is further corroborated using magnetization data for H∥cH \parallel c in a single crystal of FeSe0.35_{0.35}Te0.65_{0.65}. Dynamical response across second magnetization peak (SMP) anomaly in FeSe0.5_{0.5}Te0.5_{0.5} has been compared with that across the well researched phenomenon of peak effect (PE) in a single crystal of CeRu2_2.Comment: 11 figures, provided additional data in another sample, added Fig.

    Hints of R-parity violation in B decays into τν\tau \nu

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    In this article we show that the recently observed enhanced semi-leptonic and leptonic decay rates of the B meson into \tau \nu modes can be explained within the frame work of R-parity violating (RPV) MSSM. In particular, RPV contributions involving the exchange of right-handed down-type squarks give a universal contribution to the B+ --> \tau \nu, B --> D \tau \nu and the B --> D* \tau \nu decays. We find that the masses and couplings that explain the enhanced B decay rates are phenomelogically viable and the squarks can possibly be observed at the LHC.Comment: 8 pages and 3 figures; Updated section 2 and 3, but results are unmodifie

    Specific heat study of single crystalline Pr0.63_{0.63} Ca0.37_{0.37} MnO3_{3} in presence of a magnetic field

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    We present the results of a study of specific heat on a single crystal of Pr0.63_{0.63}Ca0.37_{0.37}MnO3_3 performed over a temperature range 3K-300K in presence of 0 and 8T magnetic fields. An estimate of the entropy and latent heat in a magnetic field at the first order charge ordering (CO) transition is presented. The total entropy change at the CO transition which is ≈\approx 1.8 J/mol K at 0T, decreases to ∼\sim 1.5 J/mol K in presence of 8T magnetic field. Our measurements enable us to estimate the latent heat LCOL_{CO} ≈\approx 235 J/mol involved in the CO transition. Since the entropy of the ferromagnetic metallic (FMM) state is comparable to that of the charge-ordered insulating (COI) state, a subtle change in entropy stabilises either of these two states. Our low temperature specific heat measurements reveal that the linear term is absent in 0T and surprisingly not seen even in the metallic FMM state.Comment: 8 pages (in RevTEX format), 12 figures (in postscript format) Submitted to Phys. Rev.

    Implications for the future of obstetrics and gynaecology following the COVID-19 pandemic: a commentary.

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    In March 2020, the World Health Organization (WHO) declared COVID-19 a global pandemic. At the time of writing, more than 261,184 cases of COVID-19 have been confirmed in the UK resulting in over 36,914 directly attributable deaths.1 The National Health Service (NHS) has been confronted with the unprecedented task of dealing with the enormity of the resultant morbidity and mortality. In addition, the workforce has been depleted as a direct consequence of the disease, in most cases temporarily, but in some tragic cases permanently

    Flavor Violating Higgs Decays

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    We study a class of nonstandard interactions of the newly discovered 125 GeV Higgs-like resonance that are especially interesting probes of new physics: flavor violating Higgs couplings to leptons and quarks. These interaction can arise in many frameworks of new physics at the electroweak scale such as two Higgs doublet models, extra dimensions, or models of compositeness. We rederive constraints on flavor violating Higgs couplings using data on rare decays, electric and magnetic dipole moments, and meson oscillations. We confirm that flavor violating Higgs boson decays to leptons can be sizeable with, e.g., h -> tau mu and h -> tau e branching ratios of order 10% perfectly allowed by low energy constraints. We estimate the current LHC limits on h -> tau mu and h -> tau e decays by recasting existing searches for the SM Higgs in the tau-tau channel and find that these bounds are already stronger than those from rare tau decays. We also show that these limits can be improved significantly with dedicated searches and we outline a possible search strategy. Flavor violating Higgs decays therefore present an opportunity for discovery of new physics which in some cases may be easier to access experimentally than flavor conserving deviations from the Standard Model Higgs framework.Comment: 39 pages, 12 figures, 3 tables; v2: Improved referencing, updated mu -> 3e bounds to include large loop contributions, corrected single top constraints; conclusions unchanged; matches version to be published in JHEP; v3: included 2-loop contributions in mu -> e conversion, improved discussion of tau -> 3 mu and of EDM constraints on FV top-Higgs couplings; conclusions unchange

    Thrombolytic removal of intraventricular haemorrhage in treatment of severe stroke: results of the randomised, multicentre, multiregion, placebo-controlled CLEAR III trial

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    Background: Intraventricular haemorrhage is a subtype of intracerebral haemorrhage, with 50% mortality and serious disability for survivors. We aimed to test whether attempting to remove intraventricular haemorrhage with alteplase versus saline irrigation improved functional outcome. Methods: In this randomised, double-blinded, placebo-controlled, multiregional trial (CLEAR III), participants with a routinely placed extraventricular drain, in the intensive care unit with stable, non-traumatic intracerebral haemorrhage volume less than 30 mL, intraventricular haemorrhage obstructing the 3rd or 4th ventricles, and no underlying pathology were adaptively randomly assigned (1:1), via a web-based system to receive up to 12 doses, 8 h apart of 1 mg of alteplase or 0·9% saline via the extraventricular drain. The treating physician, clinical research staff, and participants were masked to treatment assignment. CT scans were obtained every 24 h throughout dosing. The primary efficacy outcome was good functional outcome, defined as a modified Rankin Scale score (mRS) of 3 or less at 180 days per central adjudication by blinded evaluators. This study is registered with ClinicalTrials.gov, NCT00784134. Findings: Between Sept 18, 2009, and Jan 13, 2015, 500 patients were randomised: 249 to the alteplase group and 251 to the saline group. 180-day follow-up data were available for analysis from 246 of 249 participants in the alteplase group and 245 of 251 participants in the placebo group. The primary efficacy outcome was similar in each group (good outcome in alteplase group 48% vs saline 45%; risk ratio [RR] 1·06 [95% CI 0·88–1·28; p=0·554]). A difference of 3·5% (RR 1·08 [95% CI 0·90–1·29], p=0·420) was found after adjustment for intraventricular haemorrhage size and thalamic intracerebral haemorrhage. At 180 days, the treatment group had lower case fatality (46 [18%] vs saline 73 [29%], hazard ratio 0·60 [95% CI 0·41–0·86], p=0·006), but a greater proportion with mRS 5 (42 [17%] vs 21 [9%]; RR 1·99 [95% CI 1·22–3·26], p=0·007). Ventriculitis (17 [7%] alteplase vs 31 [12%] saline; RR 0·55 [95% CI 0·31–0·97], p=0·048) and serious adverse events (114 [46%] alteplase vs 151 [60%] saline; RR 0·76 [95% CI 0·64–0·90], p=0·002) were less frequent with alteplase treatment. Symptomatic bleeding (six [2%] in the alteplase group vs five [2%] in the saline group; RR 1·21 [95% CI 0·37–3·91], p=0·771) was similar. Interpretation: In patients with intraventricular haemorrhage and a routine extraventricular drain, irrigation with alteplase did not substantially improve functional outcomes at the mRS 3 cutoff compared with irrigation with saline. Protocol-based use of alteplase with extraventricular drain seems safe. Future investigation is needed to determine whether a greater frequency of complete intraventricular haemorrhage removal via alteplase produces gains in functional status
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