Influence of shock-bubble and bubble-bubble interactions on the collapse of a cluster of bubbles

The present work is concerned with direct numerical simulations for the shock-bubble and bubble-bubble interactions using the improved ghost fluid method in which the Riemann solutions are utilized to diminish numerical oscillations near interfaces. The influence of bubble size and bubble-bubble distance on the collapse of in-line two bubbles and in-line three bubbles are investigated to understand the conditions under which the bubble-bubble interactions accelerate or decelerate the bubble collapse. It is shown that when the in-line bubbles collapse by the incident shock wave, the collapse of the downstream bubble can be accelerated by the shock waves due to the collapse of upstream bubbles, while the collapse of the upstream bubbles is decelerated by the expansion wave cased by the reflection of the incident shock wave at the surface of the downstream bubbles. Also, there exists the bubble-bubble distance in which the collapse of the downstream bubble is most accelerated. When the downstream bubble is smaller than the upstream bubble, the downstream bubble collapses more violently than the single bubble at any distance between the bubbles. The phase of the downstream bubble at the impact of the shock waves generated from the upstream bubbles is important in determining the acceleration of the collapse of the downstream bubble. It is also shown that the pressure increase in liquid near the axis of symmetry around the downstream bubble increases with the increase of number of bubbles and with the decrease of the bubble-bubble distance because the pressure increase in liquid is caused by the superposition of the shock waves generated from all bubbles.http://deepblue.lib.umich.edu/bitstream/2027.42/84251/1/CAV2009-final53.pd

Isolating signatures of major cloud-cloud collisions - II. The lifetimes of broad bridge features

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.We investigate the longevity of broad bridge features in position–velocity diagrams that appear as a result of cloud–cloud collisions. Broad bridges will have a finite lifetime due to the action of feedback, conversion of gas into stars and the time-scale of the collision. We make a series of analytic arguments with which to estimate these lifetimes. Our simple analytic arguments suggest that for collisions between clouds larger than R ∼ 10 pc the lifetime of the broad bridge is more likely to be determined by the lifetime of the collision rather than the radiative or wind feedback disruption time-scale. However, for smaller clouds feedback becomes much more effective. This is because the radiative feedback time-scale scales with the ionizing flux Nly as R7/4N−1/4ly R7/4Nly−1/4 so a reduction in cloud size requires a relatively large decrease in ionizing photons to maintain a given time-scale. We find that our analytic arguments are consistent with new synthetic observations of numerical simulations of cloud–cloud collisions (including star formation and radiative feedback). We also argue that if the number of observable broad bridges remains ∼ constant, then the disruption time-scale must be roughly equivalent to the collision rate. If this is the case, our analytic arguments also provide collision rate estimates, which we find are readily consistent with previous theoretical models at the scales they consider (clouds larger than about 10 pc) but are much higher for smaller clouds.Peer reviewe

Linfoma multicêntrico com metástase no sistema nervoso central em cão. Relato de caso

O artigo não apresenta resumo

Isolating signatures of major cloud-cloud collisions using position-velocity diagrams

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.Collisions between giant molecular clouds are a potential mechanism for triggering the formation of massive stars, or even super star clusters. The trouble is identifying this process observationally and distinguishing it from other mechanisms. We produce synthetic position–velocity diagrams from models of cloud–cloud collisions, non-interacting clouds along the line of sight, clouds with internal radiative feedback and a more complex cloud evolving in a galactic disc, to try and identify unique signatures of collision. We find that a broad bridge feature connecting two intensity peaks, spatially correlated but separated in velocity, is a signature of a high-velocity cloud–cloud collision. We show that the broad bridge feature is resilient to the effects of radiative feedback, at least to around 2.5 Myr after the formation of the first massive (ionizing) star. However for a head-on 10 km s−1 collision, we find that this will only be observable from 20 to 30 per cent of viewing angles. Such broad–bridge features have been identified towards M20, a very young region of massive star formation that was concluded to be a site of cloud–cloud collision by Torii et al., and also towards star formation in the outer Milky Way by Izumi et al.Peer reviewe

Transmissão vertical natural por Hepatozoon canis em neonatos caninos. Relato de caso

O artigo não apresenta resumo

Análise qualitativa de cálculos relacionada com idade, sexo, raça e localização no trato urinário de cães

O artigo não apresenta resumo

Economical, green, and safe route towards substituted lactones by anodic generation of oxycarbonyl radicals

A new electrochemical methodology has been developed for the generation of oxycarbonyl radicals under mild and green conditions from readily available hemioxalate salts. Mono‐ and multi‐functionalised γ‐butyrolactones were synthesised through exo‐cyclisation of these oxycarbonyl radicals with an alkene, followed by the sp3–sp3 capture of the newly formed carbon‐centred radical. The synthesis of functionalised valerolactone derivatives was also achieved, demonstrating the versatility of the newly developed methodology. This represents a viable synthetic route towards pharmaceutically important fragments and further demonstrates the practicality of electrosynthesis as a green and economical method to activate small organic molecules

Citrus aurantium L. essential oil exhibits anxiolytic-like activity mediated by 5-HT1A-receptors and reduces cholesterol after repeated oral treatment

Abstract\ud \ud \ud \ud Background\ud \ud The current treatments for anxiety disorders and depression have multiple adverse effects in addition to a delayed onset of action, which has prompted efforts to find new substances with potential activity in these disorders. Citrus aurantium was chosen based on ethnopharmacological data because traditional medicine refers to the Citrus genus as useful in diminishing the symptoms of anxiety or insomnia, and C. aurantium has more recently been proposed as an adjuvant for antidepressants. In the present work, we investigated the biological activity underlying the anxiolytic and antidepressant effects of C. aurantium essential oil (EO), the putative mechanism of the anxiolytic-like effect, and the neurochemical changes in specific brain structures of mice after acute treatment. We also monitored the mice for possible signs of toxicity after a 14-day treatment.\ud \ud \ud \ud Methods\ud \ud The anxiolytic-like activity of the EO was investigated in a light/dark box, and the antidepressant activity was investigated in a forced swim test. Flumazenil, a competitive antagonist of benzodiazepine binding, and the selective 5-HT1A receptor antagonist WAY100635 were used in the experimental procedures to determine the mechanism of action of the EO. To exclude false positive results due to motor impairment, the mice were submitted to the rotarod test.\ud \ud \ud \ud Results\ud \ud The data suggest that the anxiolytic-like activity observed in the light/dark box procedure after acute (5 mg/kg) or 14-day repeated (1 mg/kg/day) dosing was mediated by the serotonergic system (5-HT1A receptors). Acute treatment with the EO showed no activity in the forced swim test, which is sensitive to antidepressants. A neurochemical evaluation showed no alterations in neurotransmitter levels in the cortex, the striatum, the pons, and the hypothalamus. Furthermore, no locomotor impairment or signs of toxicity or biochemical changes, except a reduction in cholesterol levels, were observed after treatment with the EO.\ud \ud \ud \ud Conclusion\ud \ud This work contributes to a better understanding of the biological activity of C. aurantium EO by characterizing the mechanism of action underlying its anxiolytic-like activity.We are grateful to Dr. Márcia Ortiz M Marques and Dr. Roselaine Facanali (Laboratory of Natural Products – Instituto Agronômico (IAC), Campinas, Brazil) for the GC-MS analysis of the EO and to Vinícius Bertotti Ribeiro for technical assistance. This work was supported by grants from FAPESP (Celso ARA Costa – Proc. nº. 2006/07195-8)

Search for astronomical neutrinos from blazar TXS 0506+056 in super-kamiokande

We report a search for astronomical neutrinos in the energy region from several GeV to TeV in the direction of the blazar TXS 0506+056 using the Super-Kamiokande detector following the detection of a 100 TeV neutrinos from the same location by the IceCube collaboration. Using Super-Kamiokande neutrino data across several data samples observed from 1996 April to 2018 February we have searched for both a total excess above known backgrounds across the entire period as well as localized excesses on smaller timescales in that interval. No significant excess nor significant variation in the observed event rate are found in the blazar direction. Upper limits are placed on the electron- and muon-neutrino fluxes at the 90% confidence level as 6.0 × 10−7 and 4.5 × 10−7–9.3 × 10−10 [erg cm−2 s−1], respectively