The magnitude and impact of the Youngest Toba Tuff super-eruption

Super-eruptions, orders of magnitude larger than biggest eruptions experienced in historic times, have devastated wide areas by pyroclastic flows, covered continent-size areas by ash fallout, and injected large quantities of aerosols into the stratosphere affecting global climate. The Youngest Toba Tuff (YTT) is the largest known super-eruption in the Quaternary. Here we reconstructed the ultra-distal volcanic ash dispersal during this super-eruption using a computational ash dispersal model, which provides insights into the eruption dynamics and the impact of the event. The method uses a 3D time-dependent tephra dispersion model, a set of wind fields, and several tens of thickness measurements of the YTT tephra deposit. Results reveal that the YTT eruption dispersed ∼8600km3 (∼3800km3 dense rock equivalent, DRE) of ash, covering ∼40 million km2 with more than 5mm of ash. These new fallout volume estimations indicate that the total volume of the material erupted (including the massive pyroclastic density current (PDC), 1500km3 DRE, deposits on Sumatra) was ∼5300km3 DRE. Simulation results indicate that the eruption had a very large mass flow rate and that the umbrella cloud, associated with the eruption plume, spread as an enormous gravity current around the neutral buoyancy level. The YTT tephra forms a key chronostratigraphic marker in the sedimentary sequences, and is particularly useful for constraining the age of the palaeoenvironmental and archeological records, and synchronizing these archives to investigate temporal relationships. These new constraints on the extent of the YTT deposit are therefore particularly useful for cryptotephra studies that aim to find nonvisible tephra layers for these chronological purposes. This method used to constrain volcanological parameters of eruptions in the past provides insights into the dispersal processes, and allows the amount of volatiles released to be estimated which is crucial to assessing the impact of such events

History and philosophy of science in Biology teaching

Neste trabalho, buscamos evidenciar a concepção de História da Biologia que é veiculada nos livros didáticos. Para tanto, analisamos três coleções de livros de Biologia destinados ao Ensino Médio, e alguns livros universitários usados em cursos de formação de professores. Ao analisar este material curricular foi possível observar que a história apresentada é desvinculada do contexto cultural de cada período histórico, o que pode levar o aluno a construir uma falsa representação da ciência e do fazer científico.In this work, we search forto evidences the conception of the History of Biology being is propagated in textbooks. We analyze three Biology book collections designed estined forto middle schooledium education, and some university books used in teacher education courses. When analyzing this curricular material it was possible to observe that the history of biology presented is disengaged from entailedofthe cultural context of each historical period, and this what can lead the student to construct a false representation of science and of scientific meaning making

Relapsing polychondritis: state of the art on clinical practice guidelines

Due to the rarity of relapsing polychondritis (RP), many unmet needs remain in the management of RP. Here, we present a systematic review of clinical practice guidelines (CPGs) published for RP, as well as a list of the most striking unmet needs for this rare disease. We carried out a systematic search in PubMed and Embase based on controlled terms (medical subject headings and Emtree) and keywords of the disease and publication type (CPGs). The systematic literature review identified 20 citations, among which no CPGs could be identified. We identified 11 main areas with unmet needs in the field of RP: the diagnosis strategy for RP; the therapeutic management of RP; the management of pregnancy in RP; the management of the disease in specific age groups (for instance in paediatric-onset RP); the evaluation of adherence to treatment; the follow-up of patients with RP, including the frequency of screening for the potential complications and the optimal imaging tools for each involved region; perioperative and anaesthetic management (due to tracheal involvement); risk of neoplasms in RP, including haematological malignancies; the prevention and management of infections; tools for assessment of disease activity and damage; and patient-reported outcomes and quality of life indicators. Patients and physicians should work together within the frame of the ReCONNET network to derive valuable evidence for obtaining literature-informed CPGs

Space charge saturated sheath regime and electron temperature saturation in Hall thrusters

Secondary electron emission in Hall thrusters is predicted to lead to space charge saturated wall sheaths resulting in enhanced power losses in the thruster channel. Analysis of experimentally obtained electron-wall collision frequency suggests that the electron temperature saturation, which occurs at high discharge voltages, appears to be caused by a decrease of the Joule heating rather than by the enhancement of the electron energy loss at the walls due to a strong secondary electron emission

Effect of Carnitine and herbal mixture extract on obesity induced by high fat diet in rats

<p>Abstract</p> <p>Background</p> <p>Obesity-associated type 2 diabetes is rapidly increasing throughout the world. It is generally recognized that natural products with a long history of safety can modulate obesity.</p> <p>Aim</p> <p>To investigate the development of obesity in response to a high fat diet (HFD) and to estimate the effect of L-carnitine and an Egyptian Herbal mixture formulation (HMF) (consisting of T. chebula, Senae, rhubarb, black cumin, aniseed, fennel and licorice) on bodyweight, food intake, lipid profiles, renal, hepatic, cardiac function markers, lipid Peroxidation, and the glucose and insulin levels in blood and liver tissue in rats.</p> <p>Method</p> <p>White male albino rats weighing 80-90 gm, 60 days old. 10 rats were fed a normal basal diet (Cr), 30 rats fed a high-fat diet (HFD) for 14 weeks during the entire study. Rats of the HFD group were equally divided into 3 subgroups each one include 10 rats. The first group received HFD with no supplement (HFD), the 2^ndgroup HFD+L-carnitine and the third group received HFD+HMF. Carnitine and HMF were administered at 10^thweek (start time for treatments) for 4 weeks.</p> <p>Body weight, lipid profile & renal function (urea, uric acid creatinine) ALT & AST activities, cardiac markers, (LDH, C.K-NAC and MB) the oxidative stress marker reduced glutathione (GSH), and Malondialdehyde (MDA) catalase activity, in addition to glucose, insulin, and insulin resistance in serum & tissues were analyzed.</p> <p>Results</p> <p>Data showed that feeding HFD diet significantly increased final body weight, triglycerides (TG), total cholesterol, & LDL concentration compared with controls, while significantly decreasing HDL; meanwhile treatment with L-carnitine, or HMF significantly normalized the lipid profile.</p> <p>Serum ALT, urea, uric acid, creatinine, LDH, CK-NAC, CK-MB were significantly higher in the high fat group compared with normal controls; and administration of L-carnitine or herbal extract significantly lessened the effect of the HFD. Hyperglycemia, hyperinsulinemia, and high insulin resistance (IR) significantly increased in HFD in comparison with the control group. The treatment with L-carnitine or HMF improved the condition. HFD elevated hepatic MDA and lipid peroxidation associated with reduction in hepatic GSH and catalase activity; whereas administration of L-carnitine or herbal extract significantly ameliorated these hepatic alterations.</p> <p>Conclusion</p> <p>HFD induced obesity associated with a disturbed lipid profile, defective antioxidant stability, and high values of IR parameters; this may have implications for the progress of obesity related problems. Treatment with L-carnitine, or HMF extract improved obesity and its associated metabolic problems in different degrees. Also HMF has antioxidant, hypolipidaemic insulin sensitizing effects. Moreover HMF might be a safe combination on the organs whose functions were examined, as a way to surmount the obesity state; and it has a distinct anti-obesity effect.</p