Regimes of stratified turbulence at low Prandtl number

Quantifying transport by strongly stratified turbulence in low Prandtl number ($Pr$) fluids is critically important for the development of better models for the structure and evolution of stellar interiors. Motivated by recent numerical simulations showing strongly anisotropic flows suggestive of scale-separated dynamics, we perform a multiscale asymptotic analysis of the governing equations. We find that, in all cases, the resulting slow-fast system naturally takes a quasilinear form. Our analysis also reveals the existence of several distinct dynamical regimes depending on the emergent buoyancy Reynolds and P\'eclet numbers, $Re_b = \alpha^2 Re$ and $Pe_b = Pr Re_b$, respectively, where $\alpha$ is the aspect ratio of the large-scale turbulent flow structures, and $Re$ is the outer scale Reynolds number. Scaling relationships relating the aspect ratio, the characteristic vertical velocity, and the strength of the stratification (measured by the Froude number $Fr$) naturally emerge from the analysis. When $Pe_b \ll \alpha$, the dynamics at all scales is dominated by buoyancy diffusion, and our results recover the scaling laws empirically obtained from direct numerical simulations by Cope et al. (2020). For $Pe_b \ge O(1)$, diffusion is negligible (or at least subdominant) at all scales and our results are consistent with those of Chini et al. (2022) for strongly stratified geophysical turbulence at $Pr = O(1)$.Finally, we have identified a new regime for $\alpha \ll Pe_b \ll 1$, in which slow, large scales are diffusive while fast, small scales are not. We conclude by presenting a map of parameter space that clearly indicates the transitions between isotropic turbulence, non-diffusive stratified turbulence, diffusive stratified turbulence and viscously-dominated flows.Comment: 25 pages, 1 figur

Reviving Religious Modesty in the Face of Radicalism Ideology: The Experience of SMA Al-Azhar Menganti Gresik, Indonesia

By radicalising educational institutions, this study would like to see an overview of the development of radicalism ideology in educational institutions, as well as the response of teachers in forums across Religious Secondary Schools (SMA) and National Secondary Schools (SMK) in East Java. Sekolah Menengah Al-Azhar Menganti Gresik, one of the educational institutions based on the pesantren system, has held a programme to restore religious moderation as a solution to radicalism. The emergence of the aforementioned programme has piqued the interest of researchers in conducting an objective analysis of school strategies for promoting religious moderation among students. This study employs a qualitative approach with a case study approach at SMA Al-Azhar Menganti Gresik, as well as data collection techniques such as observations, interviews, and documentation. Miles and Hubarman analysis was used to perform objective analysis. Objectively, the study’s findings indicate that the process of reviving religious moderation requires strong support from educational stakeholders in private schools, specifically foundations. The importance of the top-down model in implementing rehabilitation programmes on religious moderation, as Giddens and Singh explain, determines the success of educational institutions in combating the radicalism movement. Keywords: Religious Modesty; Radicalism Ideology; Experience of SMA Al-Azhar Mengant

Merchants of knowledge: Petty retail and differentiation without consolidation among farmers in Maharashtra, India

This article focuses on the intermediary figure of the village‐level petty retailer of chemical inputs, providing an account of the everyday relationships of farmers with transnational and domestic agribusiness capital. Retailers are figures from whom farmers purchase seeds, fertilizers, pesticides, and other chemicals. The article traces the rise of village‐level retailers in western Maharashtra, India, since the 1990s, and finds that Maratha (a dominant landholding cultivator caste) households have ventured into retailing. Further, farmers depend on retailers for credit, technical knowledge, and for the sale of their harvest. By analysing the pressures and risks of petty retail, visible in interactions with farmers, the article argues that even as retailing provides avenues for upward mobility to petty agricultural commodity producers, the trade is too volatile for the gains to sustain. Thus, the entry of Marathas into petty retail is akin to an attempt at class differentiation but without consolidation.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/144696/1/joac12249.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/144696/2/joac12249_am.pd

Gravitational Waves From Known Pulsars: Results From The Initial Detector Era

We present the results of searches for gravitational waves from a large selection of pulsars using data from the most recent science runs (S6, VSR2 and VSR4) of the initial generation of interferometric gravitational wave detectors LIGO (Laser Interferometric Gravitational-wave Observatory) and Virgo. We do not see evidence for gravitational wave emission from any of the targeted sources but produce upper limits on the emission amplitude. We highlight the results from seven young pulsars with large spin-down luminosities. We reach within a factor of five of the canonical spin-down limit for all seven of these, whilst for the Crab and Vela pulsars we further surpass their spin-down limits. We present new or updated limits for 172 other pulsars (including both young and millisecond pulsars). Now that the detectors are undergoing major upgrades, and, for completeness, we bring together all of the most up-to-date results from all pulsars searched for during the operations of the first-generation LIGO, Virgo and GEO600 detectors. This gives a total of 195 pulsars including the most recent results described in this paper.United States National Science FoundationScience and Technology Facilities Council of the United KingdomMax-Planck-SocietyState of Niedersachsen/GermanyAustralian Research CouncilInternational Science Linkages program of the Commonwealth of AustraliaCouncil of Scientific and Industrial Research of IndiaIstituto Nazionale di Fisica Nucleare of ItalySpanish Ministerio de Economia y CompetitividadConselleria d'Economia Hisenda i Innovacio of the Govern de les Illes BalearsNetherlands Organisation for Scientific ResearchPolish Ministry of Science and Higher EducationFOCUS Programme of Foundation for Polish ScienceRoyal SocietyScottish Funding CouncilScottish Universities Physics AllianceNational Aeronautics and Space AdministrationOTKA of HungaryLyon Institute of Origins (LIO)National Research Foundation of KoreaIndustry CanadaProvince of Ontario through the Ministry of Economic Development and InnovationNational Science and Engineering Research Council CanadaCarnegie TrustLeverhulme TrustDavid and Lucile Packard FoundationResearch CorporationAlfred P. Sloan FoundationAstronom

First searches for optical counterparts to gravitational-wave candidate events

During the Laser Interferometer Gravitational-wave Observatory and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers showed strong evidence for being astrophysical in nature. We compare the sensitivities of these observations to several model light curves from possible sources of interest, and discuss prospects for future joint GW-optical observations of this type

PANC Study (Pancreatitis: A National Cohort Study): national cohort study examining the first 30 days from presentation of acute pancreatitis in the UK

Abstract Background Acute pancreatitis is a common, yet complex, emergency surgical presentation. Multiple guidelines exist and management can vary significantly. The aim of this first UK, multicentre, prospective cohort study was to assess the variation in management of acute pancreatitis to guide resource planning and optimize treatment. Methods All patients aged greater than or equal to 18 years presenting with acute pancreatitis, as per the Atlanta criteria, from March to April 2021 were eligible for inclusion and followed up for 30 days. Anonymized data were uploaded to a secure electronic database in line with local governance approvals. Results A total of 113 hospitals contributed data on 2580 patients, with an equal sex distribution and a mean age of 57 years. The aetiology was gallstones in 50.6 per cent, with idiopathic the next most common (22.4 per cent). In addition to the 7.6 per cent with a diagnosis of chronic pancreatitis, 20.1 per cent of patients had a previous episode of acute pancreatitis. One in 20 patients were classed as having severe pancreatitis, as per the Atlanta criteria. The overall mortality rate was 2.3 per cent at 30 days, but rose to one in three in the severe group. Predictors of death included male sex, increased age, and frailty; previous acute pancreatitis and gallstones as aetiologies were protective. Smoking status and body mass index did not affect death. Conclusion Most patients presenting with acute pancreatitis have a mild, self-limiting disease. Rates of patients with idiopathic pancreatitis are high. Recurrent attacks of pancreatitis are common, but are likely to have reduced risk of death on subsequent admissions. </jats:sec

FIRST SEARCHES FOR OPTICAL COUNTERPARTS TO GRAVITATIONAL-WAVE CANDIDATE EVENTS

During the LIGO and Virgo joint science runs in 2009-2010, gravitational wave (GW) data from three interferometer detectors were analyzed within minutes to select GW candidate events and infer their apparent sky positions. Target coordinates were transmitted to several telescopes for follow-up observations aimed at the detection of an associated optical transient. Images were obtained for eight such GW candidates. We present the methods used to analyze the image data as well as the transient search results. No optical transient was identified with a convincing association with any of these candidates, and none of the GW triggers showed strong evidence for being astrophysical in nature. We compare the sensitivities of these observations to several model light curves from possible sources of interest, and discuss prospects for future joint GW-optical observations of this type

Search for long-lived gravitational-wave transients coincident with long gamma-ray bursts

Long gamma-ray bursts (GRBs) have been linked to extreme core-collapse supernovae from massive stars. Gravitational waves (GW) offer a probe of the physics behind long GRBs. We investigate models of long-lived (~10–1000 s) GW emission associated with the accretion disk of a collapsed star or with its protoneutron star remnant. Using data from LIGO’s fifth science run, and GRB triggers from the Swift experiment, we perform a search for unmodeled long-lived GW transients. Finding no evidence of GW emission, we place 90% confidence-level upper limits on the GW fluence at Earth from long GRBs for three waveforms inspired by a model of GWs from accretion disk instabilities. These limits range from F<3:5 ergs cm⁻2 to F<1200 ergs cm⁻2, depending on the GRB and on the model, allowing us to probe optimistic scenarios of GW production out to distances as far as ≈ 33 Mpc. Advanced detectors are expected to achieve strain sensitivities 10× better than initial LIGO, potentially allowing us to probe the engines of the nearest long GRBs.J. Aasi ... D.J. Hosken ... W. Kim ... E.J. King ... J. Munch ... D. J. Ottaway ... P. J. Veitc

Searching for stochastic gravitational waves using data from the two colocated LIGO Hanford detectors

Searches for a stochastic gravitational-wave background (SGWB) using terrestrial detectors typically involve cross-correlating data from pairs of detectors. The sensitivity of such cross-correlation analyses depends, among other things, on the separation between the two detectors: the smaller the separation, the better the sensitivity. Hence, a colocated detector pair is more sensitive to a gravitational-wave background than a noncolocated detector pair. However, colocated detectors are also expected to suffer from correlated noise from instrumental and environmental effects that could contaminate the measurement of the background. Hence, methods to identify and mitigate the effects of correlated noise are necessary to achieve the potential increase in sensitivity of colocated detectors. Here we report on the first SGWB analysis using the two LIGO Hanford detectors and address the complications arising from correlated environmental noise. We apply correlated noise identification and mitigation techniques to data taken by the two LIGO Hanford detectors, H1 and H2, during LIGO’s fifth science run. At low frequencies, 40–460 Hz, we are unable to sufficiently mitigate the correlated noise to a level where we may confidently measure or bound the stochastic gravitational-wave signal. However, at high frequencies, 460–1000 Hz, these techniques are sufficient to set a 95% confidence level upper limit on the gravitational-wave energy density of Ω(f) < 7.7 × 10[superscript -4](f/900  Hz)[superscript 3], which improves on the previous upper limit by a factor of ~180. In doing so, we demonstrate techniques that will be useful for future searches using advanced detectors, where correlated noise (e.g., from global magnetic fields) may affect even widely separated detectors.National Science Foundation (U.S.)United States. National Aeronautics and Space AdministrationCarnegie TrustDavid & Lucile Packard FoundationAlfred P. Sloan Foundatio

Modeling Freshwater Supply from its Origin: at High-Altitude Glaciers

Meltwater from glaciers in high-altitude mountains feed the populations that live in their basins and catchment areas. Their freshwater supply, hydroelectric power and irrigation is extremely sensitive to the changing climate conditions. This study investigates the impact on freshwater supply under these conditions by modeling the mass balance of high-altitude glaciers. The two areas whose mass balances have been investigated are the Himalayas and the Andes. There are 1.3 billion people who depend on Himalayan glaciers as their source of water. The Andean region has 3.5 million residents all of whom depend almost entirely on the meltwater from the mountain's glaciers. This study examines the Himalayas and the Andes, and also analyses freshwater supply from 1950 to the present day and projects the impact on freshwater supply to 2100, providing suggestions for freshwater resource management. The results show that the Himalayan glaciers have increasingly negative mass balance, implying the glaciers are shrinking. Projections computed in this study indicate that important glaciers, such as the Dokirani glacier that is a source of water for the River Ganga, will disappear by the 2060s. The most notable exception is the Karakoram region of the Himalayas whose anomalously high precipitation leads to increasing mass balances and glaciers that grow over time. One of the biggest geostrategic implications is that the highest active warzone in the world, Siachen glacier, will continue to grow. Furthermore it will be a source of freshwater for regions that lack it, increasing the need for a water agreement and a peaceful settlement. The results of this study show that Andes have mass balances that are not only lower but also decreasing at a quicker rate. The principal areas of interest are the central Andes and the Northern and Southern Patagonian ice fields. Glaciers in the central Andes are projected to disappear by 2100. The glaciers in the Central Andes are seen to shrink at an alarming rate from the 2030s onwards, and several of these glaciers' masses approach zero. In the Patagonia icefield, particularly in the southern icefield which contains the most (and largest) glaciers, the shrinking glaciers and their falling mass balances severely restrict the freshwater supply available to the region. For instance Parinacota 01 glacier is projected to disappear in the 2020s and Solimana glacier is projected to disappear between 2060 and 2100. The projections of freshwater supply and recommendations for resource management that this study makes point to a future with water shortages, bilateral water agreements and an increasing need for vulnerability analyses and proactive freshwater distribution today