Uncertainties in stellar evolution models: convective overshoot

In spite of the great effort made in the last decades to improve our understanding of stellar evolution, significant uncertainties remain due to our poor knowledge of some complex physical processes that require an empirical calibration, such as the efficiency of the interior mixing related to convective overshoot. Here we review the impact of convective overshoot on the evolution of stars during the main Hydrogen and Helium burning phases.Comment: Proc. of the workshop "Asteroseismology of stellar populations in the Milky Way" (Sesto, 22-26 July 2013), Astrophysics and Space Science Proceedings, (eds. A. Miglio, L. Girardi, P. Eggenberger, J. Montalban

CARDIOPROTECTIVE EFFECT OF MENTHA LONGIFOLIA AGAINST CYCLOPHOSPHAMIDE INDUCED CARDIOTOXICITY IN RATS: A BIOCHEMICAL, ELECTROCARDIOGRAPHIC AND HISTOPATHOLOGICAL STUDY

Objective: The current research was designed to evaluate the cardioprotective activity of Mentha longifolia (ML) leaf extract on cyclophosphamide-induced cardiotoxicity in rats.Methods: Cardiotoxicity was induced in Albino wistar rats of either sex by administering a single injection of cyclophosphamide (200 mg/kg, i. p.) on the first day of the experimental period. Mentha longifolia (250 and 500 mg/kg, p. o.) was administered daily for 10 d immediately after administration of cyclophosphamide on the first day. The general observations such as oxidative marker enzyme assays, ECG and histopathology were examined.Results: Cyclophosphamide administration significantly (p<0.05) increased lipid peroxidation (LPO) and decreased the levels of antioxidant markers such as superoxide dismutase (SOD) and catalase (CAT). Cyclophosphamide elevated the levels of biomarker enzymes like creatine kinase isoenzyme MB (CK-MB), creatine kinase isoenzyme NAC (CK-NAC) and lactate dehydrogenase (LDH). Further, the cyclophosphamide-treated rats showed changes in electrocardiographic parameters. Treatment with Mentha longifolia significantly (p<0.05) reversed the status of cardiac biomarkers, ECG and oxidative enzymes in cyclophosphamide-induced cardiotoxicity. Histopathological examination was also supported the potential cardioprotective effect of Mentha longifolia with reduced damage to the myocardium.Conclusion: The biochemical, ECG and histopathology reports support the potential benefits of Mentha longifolia against myocardial damage which could be attributed to antioxidant activity

Observation of direct and indirect magnetoelectricity in lead free ferroelectric (Na 0.5Bi 0.5TiO 3)-magnetostrictive (CoFe 2O 4) particulate composite

A particulate composite consisting of 65 mol. % Na 0.5Bi 0.5TiO 3 and 35 mol. % CoFe 2O 4 was synthesized, and it's structure, microstructure, ferroelectric, magnetostrictive, magnetic, and direct/indirect magnetoelectric properties were studied. The composite showed different magnetization behaviour under electrically poled and un-poled conditions. The percentage change in magnetization as a result of poling is approximately -15% at 500 Oe magnetic field. Magnetostriction measurements displayed a value of λ 11 = -57 × 10 -6 and piezomagnetic coefficient δλ 11/δH = 0.022 × 10 -6 kOe -1 at 2.2 kOe for the composite. The maximum magnetoelectric output varied from 1350 mV/cm to 2000 mV/cm with change in the electrical poling condition

Helium Nova on a Very Massive White Dwarf -- A Light Curve Model of V445 Puppis (2000) Revised

V445 Pup (2000) is a unique object identified as a helium nova. Color indexes during the outburst are consistent with those of free-free emission. We present a free-free emission dominated light curve model of V445 Pup on the basis of the optically thick wind theory. Our light curve fitting shows that (1) the white dwarf (WD) mass is very massive (M_WD \gtrsim 1.35 M_\sun), and (2) a half of the accreted matter remains on the WD, both of which suggest that the increasing WD mass. Therefore, V445 Pup is a strong candidate of Type Ia supernova progenitor. The estimated distance to V445 Pup is now consistent with the recent observational suggestions, 3.5 < d < 6.5 kpc. A helium star companion is consistent with the brightness of m_v=14.5 mag just before the outburst, if it is a little bit evolved hot (\log T (K) \gtrsim 4.5) star with the mass of M_He \gtrsim 0.8 M_\sun. We then emphasize importance of observations in the near future quiescent phase after the thick circumstellar dust dissipates away, especially its color and magnitude to specify the nature of the companion star. We have also calculated helium ignition masses for helium shell flashes against various helium accretion rates and discussed the recurrence period of helium novae.Comment: 8 pages including 12 figures, to appear in Ap

Data Analysis in the Twenty-First Century

The 21st Century is characterized by complex multidisciplinary problems accompanied by massive datasets. 'We are drowning in data, but starving for knowledge', as the volumes of many commercial, industrial and scientific datasets have exceeded the terabyte range and are approaching petabytes and beyond. Statistical methodology has long been employed to find useful and usable information in data. More recently, data mining has harnessed the power of computer technology to find useful and usable patterns in such massive datasets. Although several data mining journals have joined the established statistical journals, no single journal provides an integrated treatment of statistical analysis methodology and data mining technology, particularly when applied to the solution of practical problems. This absence and the needs expressed above motivated the inauguration of John Wiley's new Journal on Statistical Analysis and Data Mining. The goals of this interdisciplinary journal are to encourage collaborations across disciplines, communication of data mining and statistical techniques to both novices and experts involved in the analysis of data from practical problems, and a principled and productive evaluation of analyses and solutions. The journal specifically encourages submission of works that have statistical rigor in the analysis of data, incorporate the most appropriate algorithms from data mining, and address the needs of applications. Applying data mining algorithms to practical problems is not sufficient, because we need to ensure that the results have a sound statistical basis, lest any decision based on these results lead to a catastrophe. Even data mining algorithms founded on sound statistical analysis are not sufficient, if they cannot solve a practical problem. Finally, employing a statistical analysis on a practical problem is not sufficient, unless it scales up to massive datasets. Statistical analysis and data mining are actually two sides of the sword that is sorely needed to conquer data overload in practical problems

Polyphosphoric acid and anhydrous aluminium chloride catalysed novel rearrangements of 1,5-diaroylcarbohydrazides

803-80

Theory of Light Emission in Sonoluminescence as Thermal Radiation

Based on the model proposed by Hilgenfeldt {\it at al.} [Nature {\bf 398}, 401 (1999)], we present here a comprehensive theory of thermal radiation in single-bubble sonoluminescence (SBSL). We first invoke the generalized Kirchhoff's law to obtain the thermal emissivity from the absorption cross-section of a multilayered sphere (MLS). A sonoluminescing bubble, whose internal structure is determined from hydrodynamic simulations, is then modelled as a MLS and in turn the thermal radiation is evaluated. Numerical results obtained from simulations for argon bubbles show that our theory successfully captures the major features observed in SBSL experiments.Comment: 17 pages, 20 figure

Impact of Stress and Decision Fatigue on Parenting Practices Related to Food and Physical Activity During COVID‐19

Background The COVID-19 pandemic has resulted in substantial disruptions to daily functioning and lifestyle behaviours, with negative health consequences for youth. Parents play a large role in their children\u27s health behaviour; yet changes to parenting behaviours during the pandemic related to food and physical activity remain relatively unexplored. The present study is the first to our knowledge to examine specific changes in American parents\u27 parenting behaviours related to food and physical activity during COVID-19, and potential correlates of such changes, including perceived stress and decision fatigue. Methods A total of 140 parents (88.57% female; 88.41% White; 87.59% married; with one to five children) from middle to upper income households completed an online survey assessing demographics, perceived stress (Perceived Stress Scale), decision fatigue (Decision Fatigue Scale) and food and activity parenting behaviour changes during COVID-19. Results Overall, a greater proportion of parents engaged primarily in positive (57.14%) than negative (22.86%) parenting practices related to food and physical activity during the pandemic. Moderation analyses showed that the negative relation between perceived stress and positive parental behaviour changes was stronger at higher perceived increases in decision fatigue during the pandemic. Conclusions In the face of a major public health crisis, adaptive parental responses may emerge, but perceived stress may inhibit such behaviour change. Perceived stress and decision fatigue may represent important explanatory factors in parental health promoting behaviours during times of uncertainty and change

Optimisation problems and replica symmetry breaking in finite connectivity spin-glasses

A formalism capable of handling the first step of hierarchical replica symmetry breaking in finite-connectivity models is introduced. The emerging order parameter is claimed to be a probability distribution over the space of field distributions (or, equivalently magnetisation distributions) inside the cluster of states. The approach is shown to coincide with the previous works in the replica symmetric case and in the two limit cases m=0,1 where m is Parisi's break-point. As an application to the study of optimization problems, the ground-state properties of the random 3-Satisfiability problem are investigated and we present a first RSB solution improving replica symmetric results.Comment: 16 pages Revtex file, 1 figure; amended version with two new appendices; to be published in J.Phys.

Effects of Bulk Viscosity in Non-linear Bubble Dynamics

The non-linear bubble dynamics equations in a compressible liquid have been modified considering the effects of compressibility of both the liquid and the gas at the bubble interface. A new bubble boundary equation has been derived, which includes a new term resulted from the liquid bulk viscosity effects. The influence of this term has been numerically investigated considering the effects of water vapor and chemical reactions on the bubble evolution. The results clearly indicate that the new term has an important damping role at the collapse, so that its consideration decreases the amplitude of the bubble rebounds after the collapse. This damping feature is more remarkable for higher deriving pressures.Comment: 4 pages, 7 figure