Amplification of Fluctuations in Unstable Systems with Disorder

We study the early-stage kinetics of thermodynamically unstable systems with quenched disorder. We show analytically that the growth of initial fluctuations is amplified by the presence of disorder. This is confirmed by numerical simulations of morphological phase separation (MPS) in thin liquid films and spinodal decomposition (SD) in binary mixtures. We also discuss the experimental implications of our results.Comment: 15 pages, 4 figure

Impact of free-stream disturbances on blunt body aerothermodynamics in hypersonic flow

The study investigates the effects of freestream disturbances (acoustic, vortical and entropy) on wall pressure and wall heat flux in front of double cone geometry in hypersonic flow. The two double cone geometries with small cone angle and high cone angles are simulated at hypersonic Mach 6 by using 2D-axisymmetric Navier Stokes Laminar flow solver, exhibit ing steady and oscillatory flow behaviour with constant inlet boundary, respectively. The acoustic (fast and slow wave), vortical and entropy disturbances with single frequency of 20 kHz and amplitude upto 1% are modelled as time-dependent inlet boundary and are introduced after achieving solutions for both cases of double-cone geometries after 5ms. The impact of these freestream disturbances was estimated by analyzing the wall pressure and wall heat flux fluctuations and it was found that rms of wall pressure fluctuation increases approxi mately 10 time and wall heat flux fluctuation increases 6 times for high angled double cone geometry, when compared to small angle double cone geometry subjected to same level of freestream disturbances.ye

Numerical investigation of non-premixed oblique detonation operations in scramjet combustor

The present study aims to develop strategies for hydrogen injection to operate scramjet combustor configuration in detonation mode at higher Mach number flights conditions. The reactive multi-species unsteady Navier-Stokes equations along with turbulence modelling are solved with detailed chemical kinetics for a two-dimensional computational domain of cavity based scramjet combustor. In order to establish detonation mode combustion a finite length wedge at angle is attached to the downstream of cavity in a scramjet combustor configuration. Initial simulations are performed at Mach 7 incoming air flow with freestream pressure of 40 kPa and temperature of 300 K for 2 ms time duration. The hydrogen fuel is injected at 30 mm upstream of cavity with angle of injection 15◦ using straight pipe of 2 mm width to provide mass flow rate equivalent to ϕ = 0.34 with respect to incoming air mass flow rate. It is found that the presence of cavity between fuel injector and wedge stabilizes the detonation mode combustion and suppress the intermittent transition between deflagration and detonation modes in comparison to without cavity case. Further the flow conditions at the starting of combustor based on hypersonic intake, operating at an altitude of 25 km with flight Mach number 9 are simulated for cavity based combustor with wegde. The outcome suggest that high temperature of incoming flow can have adverse effect to develop detonation mode combustion, but with cavity and distance between wedge and cavity stable detonation front can be established.ye

An overview of anti-diabetic plants used in Gabon: Pharmacology and Toxicology

© 2017 Elsevier B.V. All rights reserved.Ethnopharmacological relevance: The management of diabetes mellitus management in African communities, especially in Gabon, is not well established as more than 60% of population rely on traditional treatments as primary healthcare. The aim of this review was to collect and present the scientific evidence for the use of medicinal plants that are in currect by Gabonese traditional healers to manage diabetes or hyperglycaemia based here on the pharmacological and toxicological profiles of plants with anti-diabetic activity. There are presented in order to promote their therapeutic value, ensure a safer use by population and provide some bases for further study on high potential plants reviewed. Materials and methods: Ethnobotanical studies were sourced using databases such as Online Wiley library, Pubmed, Google Scholar, PROTA, books and unpublished data including Ph.D. and Master thesis, African and Asian journals. Keywords including ‘Diabetes’ ‘Gabon’ ‘Toxicity’ ‘Constituents’ ‘hyperglycaemia’ were used. Results: A total of 69 plants currently used in Gabon with potential anti-diabetic activity have been identified in the literature, all of which have been used in in vivo or in vitro studies. Most of the plants have been studied in human or animal models for their ability to reduce blood glucose, stimulate insulin secretion or inhibit carbohydrates enzymes. Active substances have been identified in 12 out of 69 plants outlined in this review, these include Allium cepa and Tabernanthe iboga. Only eight plants have their active substances tested for anti-diabetic activity and are suitables for further investigation. Toxicological data is scarce and is dose-related to the functional parameters of major organs such as kidney and liver. Conclusion: An in-depth understanding on the pharmacology and toxicology of Gabonese anti-diabetic plants is lacking yet there is a great scope for new treatments. With further research, the use of Gabonese anti-diabetic plants is important to ensure the safety of the diabetic patients in Gabon.Peer reviewedFinal Accepted Versio

Frequent Financial Reporting and Managerial Myopia

Using the transition of US firms from annual reporting to semi-annual reporting and then to quarterly reporting over the period 1950-1970, we provide evidence on the effects of increased reporting frequency on firms’ investment decisions. Estimates from difference-in-differences specifications indicate that increased reporting frequency is associated with an economically large decline in investments. Additional analyses reveal that the decline in investments is most consistent with frequent financial reporting inducing myopic management behavior. Our evidence informs the recent controversial debate about eliminating quarterly reporting for US corporations

Response to commentaries: (de)normalization of drinking and its implications for young people, sociality, culture and epidemiology

Commentar

Declining drinking among adolescents: are we seeing a denormalisation of drinking and a normalisation of non-drinking?

Background In the early 2000s, alcohol use among young people began to decline in many western countries, especially among adolescents (aged between 12-17 years old). These declines have continued steadily over the past two decades, against the backdrop of much smaller declines among the general population. Argument Hypotheses examining individual factors fail adequately to provide the necessary ‘big picture’ thinking needed to understand declines in adolescent drinking. We use the normalisation thesis to argue that there is strong international evidence for both processes of denormalisation of drinking and normalisation of non-drinking occurring for adolescents in many western countries. Conclusions Research on declining adolescent drinking provides evidence of both denormalisation of alcohol consumption and normalisation of non-drinking. This has implications for enabling policy environments more amenable to regulation and increasing the acceptability of non-drinking in social contexts. Normalisation theory (and its various interpretations) provides a useful multi-dimensional tool for understanding declines in adolescent drinking

Examining trends in the representation of young people and alcohol in Australian newspapers over twenty years (2000-2019)

Background: The news media can reflect and influence public opinion, as well as affect individual practice. In the context of significant changes in alcohol consumption among young people over the past twenty years, we examined Australian newspaper reporting of young people (under 18 years) and alcohol to assess whether there have been changes over time in the content and slant of articles that reflect or elucidate these trends. Methods: Factiva was used to search newspaper articles from major Australian newspapers over a twenty year period (2000-2019). After screening, two researchers coded 2,415 newspaper articles across four key domains: article type, article theme, sources cited and topic slant (e.g. approving, disapproving tone). Change over time across the study period was assessed using joinpoint Poisson regression analyses. Results: There was a significant increase in articles on young people and alcohol between 2000 and 2008, before a corresponding decrease to 2019. Policy or prevention strategies were the most common theme of articles (35.8%), followed by articles reporting on risks or harms associated with alcohol use for young people (18.1%). Researchers were the most common source reported (25.1%), followed by politicians (19.0%). Three quarters of articles (75.9%) had a socially disapproving topic slant, which increased significantly up until 2011, with a corresponding decrease thereafter. Conclusion: Attention to, and problematisation of, young people and alcohol increased in the first decade of this millennium which may have acted to sustain or accelerate declining drinking trends. However, this dissipated back to baseline levels in the second decade, which may indicate a lag time in recognition of young people’s drinking becoming less of a public health ‘problem’

Why is adolescent drinking declining? A systematic review and narrative synthesis

Background: Adolescent drinking has declined across many developed countries from the turn of the century. The aim of this review is to explore existing evidence examining possible reasons for this decline. Methods: We conducted systematic searches across five databases: Medline, PsycINFO, CINAHL, Informit Health and Scopus. Studies were included if association between declining alcohol consumption and potential explanatory factors were measured over time. Narrative synthesis was undertaken due to substantial methodological heterogeneity in these studies. Results: 17 studies met the inclusion criteria. Five studies found moderate evidence for changes in parental practices as a potential cause for the decline. Five studies that examined whether alcohol policy changes influenced the decline found weak evidence of association. Three studies explored whether alcohol use has been substituted by illicit substances but no evidence was found. Two studies examined the effect of a weaker economy; both identified increase in adolescent alcohol use during times of economic crisis. One study indicated that changes in exposure to alcohol advertising were positively associated with the decline and another examined the role of immigration of non-drinking populations but found no evidence of association. One study tested participation in organised sports and party lifestyle as a potential cause but did not use robust analytical methods and therefore did not provide strong evidence of association for the decline. Conclusions: The most robust and consistent evidence was identified for shifts in parental practices. Further research is required using robust analytical methods such as ARIMA modelling techniques and utilising cross-national data

“Another Person Was Going to Do It”: The Provision of Injection Drug Use Initiation Assistance in a High-Risk U.S.–Mexico Border Region

Background: Persons who inject drugs (PWID) play a key role in assisting others' initiation into injection drug use (IDU). We aimed to explore the pathways and socio-structural contexts for this phenomenon in Tijuana, Mexico, a border setting marked by a large PWID population with limited access to health and social services. Methods: Preventing Injecting by Modifying Existing Responses (PRIMER) is a multi-cohort study assessing socio-structural factors associated with PWID assisting others into initiating IDU. Semi-structured qualitative interviews in Tijuana included participants ≥18 years old, who reported IDU within the month prior to cohort enrollment and ever initiating others into IDU. Purposive sampling ensured a range of drug use experiences and behaviors related to injection initiation assistance. Thematic analysis was used to develop recurring and significant data categories. Results: Twenty-one participants were interviewed (8 women, 13 men). Broadly, participants considered public injection to increase curiosity about IDU. Many considered transitioning into IDU as inevitable. Emergent themes included providing assistance to mitigate overdose risk and to protect initiates from being taken advantage of by others. Participants described reluctance in engaging in this process. For some, access to resources (e.g., shared drugs or a monetary fee) was a motivator to initiate others. Conclusion: In Tijuana, public injection and a lack of harm reduction services are perceived to fuel the incidence of IDU initiation and to incentivize PWID to assist in injection initiation. IDU prevention efforts should address structural factors driving PWID participation in IDU initiation while including PWID in their development and implementation