Ripple and kink dynamics

We propose a relevant modification of the Nishimori-Ouchi model [{\em Phys. Rev. Lett.} {\bf 71}, 197 (1993)] for granular landscape erosion. We explicitly introduce a new parameter: the angle of repose $\theta_r$, and a new process: avalanches. We show that the $\theta_r$ parameter leads to an asymmetry of the ripples, as observed in natural patterns. The temporal evolution of the maximum ripple height $h_{max}$ is limited and not linear, according to recent observations. The ripple symmetry and the kink dynamics are studied and discussed.Comment: 7 pages, 10 figure, RevTe

Magnetohydrodynamic kink waves in two-dimensional non-uniform prominence threads

We analyse the oscillatory properties of resonantly damped transverse kink oscillations in two-dimensional prominence threads. The fine structures are modelled as cylindrically symmetric magnetic flux tubes with a dense central part with prominence plasma properties and an evacuated part, both surrounded by coronal plasma. The equilibrium density is allowed to vary non-uniformly in both the transverse and the longitudinal directions.We examine the influence of longitudinal density structuring on periods, damping times, and damping rates for transverse kink modes computed by numerically solving the linear resistive magnetohydrodynamic (MHD) equations. The relevant parameters are the length of the thread and the density in the evacuated part of the tube, two quantities that are difficult to directly estimate from observations. We find that both of them strongly influence the oscillatory periods and damping times, and to a lesser extent the damping ratios. The analysis of the spatial distribution of perturbations and of the energy flux into the resonances allows us to explain the obtained damping times. Implications for prominence seismology, the physics of resonantly damped kink modes in two-dimensional magnetic flux tubes, and the heating of prominence plasmas are discussed.Comment: 12 pages, 9 figures, A&A accepte

Using longitudinal antibiotic point prevalence survey (PPS) to drive antimicrobial stewardship programmes in a Nigerian tertiary hospital

Background: Antimicrobial stewardship (AMS) provides a means of tackling antimicrobial resistance (AMR). Unfortunately, in Nigeria, like in some other low-and-middle-income countries (LMICs), AMS practice has been lacklustre due to poor institutional support amongst other factors. Efforts were made to address this situation by engaging with the management of National Hospital Abuja, Nigeria, using antibiotic prescription information obtained through repeated point prevalence survey.Methodology: Two rounds of antibiotic PPS were conducted in 2015 and 2017 using the Global Point Prevalence Survey (G-PPS) format. Data were collected from all inpatients receiving antibiotics on the selected day of study, including patient characteristics, antimicrobial prescription details, laboratory results and information on a set of quality indicators. The data were uploaded to an online G-PPS application hosted at the University of Antwerp in Belgium for validation, analysis and reporting.Results: The PPS data showed that hospital-wide antibiotic use prevalence increased from 58% in 2015 to 61% in 2017. Surgical prophylaxis beyond 24 hours also increased from 88-90% in 2015 to 100% in 2017, and only minority of therapies were supported by laboratory input for diagnosis and monitoring; 22% in 2015 and 5% in 2017.Conclusion: These results were used for evidence-based engagement with the management to formally support AMS activities in the hospital. Positive outcomes were the formal reconstitution and inauguration of AMS committee in 2018 as well as the issuance of a formal policy statement by the hospital in 2020. The ease and free availability of Global PPS methodology makes it ideal in driving antimicrobial stewardship programme (ASP) in LMICs like Nigeria. Keywords: Antibiotic stewardship checklist, institutional support, point   French Title: Utilisation d'une enquête longitudinale sur la prévalence ponctuelle des antibiotiques (PPS) pour conduire des programmes de gestion des antimicrobiens dans un hôpital tertiaire nigérian Contexte: La gestion des antimicrobiens (AMS) offre un moyen de lutter contre la résistance aux antimicrobiens (RAM). Malheureusement, au Nigéria, comme dans certains autres pays à revenu faible ou intermédiaire (PRFI), la pratique de la MGS a été médiocre en raison d'un soutien institutionnel insuffisant, entre autres facteurs. Des  Longitudinal PPS for AMS programmes efforts ont été faits pour remédier à cette situation en collaborant avec la direction de l'hôpital national d'Abuja, au Nigéria, en utilisant les informations sur les prescriptions d'antibiotiques obtenues grâce à une enquête ponctuelle répétée de prévalence.Méthodologie: Deux séries d'antibiotiques PPS ont été menées en 2015 et 2017 en utilisant le format Global Point Prevalence Survey (G-PPS). Des données ont été recueillies auprès de tous les patients hospitalisés recevant des antibiotiques le jour sélectionné de l'étude, y compris les caractéristiques des patients, les détails de la prescription d'antimicrobiens, les résultats de laboratoire et les informations sur un ensemble d'indicateurs de qualité. Les données ont été téléchargées sur une application en ligne G-PPS hébergée à l'Université d'Anvers en Belgique à des fins de validation, d'analyse et rapports.Résultats: Les données PPS ont montré que la prévalence de l'utilisation d'antibiotiques à l'échelle de l'hôpital est passée de 58% en 2015 à 61% en 2017. La prophylaxie chirurgicale au-delà de 24 heures est également passée de 88 à 90% en 2015 à 100% en 2017, et seule une minorité de thérapies a été soutenue par entrée de laboratoire pour le diagnostic et la surveillance; 22% en 2015 et 5% en 2017.Conclusion: Ces résultats ont été utilisés pour un engagement fondé sur des données probantes avec la direction afin de soutenir officiellement les activités AMS à l'hôpital. Les résultats positifs ont été la reconstitution formelle et l'inauguration du comité AMS en 2018 ainsi que la publication d'une déclaration de politique formelle par l'hôpital en 2020. La facilité et la disponibilité gratuite de la méthodologie Global PPS la rend idéale pour conduire le programme de gestion des antimicrobiens (ASP) en PRFI comme le Nigéria. Mots clés: liste de contrôle pour la gestion des antibiotiques, soutien institutionnel, enquête ponctuelle de prévalence, déclaration de politique prevalence survey, policy statement &nbsp

Identification of targets for quality improvement in antimicrobial prescribing : the web-based ESAC Point Prevalence Survey 2009

Objectives: Since electronic prescribing is limited to few hospitals, point prevalence surveys, such as the standardized European Surveillance of Antimicrobial Consumption point prevalence survey (ESAC PPS), are an alternative tool for monitoring prescribing and helping to identify performance indicators and prescribing trends. The main objective of this study was to identify and assess targets for quality improvement. Methods: Each hospital had to carry out the survey within 2 weeks. Each department had to be surveyed in 1 day. Data collected, for all inpatients, included age and gender. For patients on systemic antimicrobial treatment, the antimicrobial/s, infection/prophylaxis site, reason in medical notes and guideline compliance were also collected. A central database using a web-based tool (WebPPS) developed in-house was used for data entry. Results: Combination of two or more antimicrobials accounted for 30% of use. Surgical prophylaxis was prolonged (>1 day) in 53% of cases. 'Intensive care' had higher proportions of treated patients (53% versus 29%), combination therapy (49% versus 31%), hospital-acquired infections (49% versus 31%) and parenteral administration (91% versus 61%). 'Reason in notes' was documented in 76%, and 'guideline compliance' occurred in 62% of patients. Conclusions: The ESAC PPS provided useful information on the quality of prescribing, which identified a number of targets for quality improvement. These could apply to specific departments or whole hospitals. Intensive care, which has different characteristics, should not be compared with general wards with respect to combination therapy, hospital-acquired infections or parenteral proportion. The study confirmed that the ESAC PPS methodology can be used on a large number of hospitals at regional, national, continental or global level.The ESAC project was supported by a grant from the European Centre for Disease Prevention and Control (ECDC; Grant Agreement 2007/001).peer-reviewe

Scalable fabrication of efficient p-n junction lead sulfide quantum dot solar cells

Nowadays, the best lead sulfide (PbS) colloidal quantum dot (CQD) solar cells are primarily demonstrated in the n-p structure, while the p-n structure is significantly less developed. This technological gap between the n-p and p-n structures is much more distinct than in cases of other solution-processable photovoltaic technologies like perovskites and polymers. Here, we propose a scalable fabrication strategy for efficient PbS QD solar cells with p-n structure. An industrially suited blade-coating technique has been used to deposit both n-type and p-type QD layers. The obtained solar cells demonstrated power conversion efficiency of 9%, thus, commensurate to the record device efficiency with this architecture fabricated with a non-scalable technique. The availability of both p-n and n-p structures fabricated from scalable methods may promote the future integration of the PbS QDs into tandem devices together with other solution-processable materials to exploit the most prominent benefits of the PbS QDs, such as infrared absorption.</p

A Compact Model of Interface-Type Memristors Linking Physical and Device Properties

Memristors are an electronic device whose resistance depends on the voltage history that has been applied to its two terminals. Despite its clear advantage as a computational element, a suitable transport model is lacking for the special class of interface-based memristors. Here, we adapt the widely-used Yakopcic compact model by including transport equations relevant to interface-type memristors. This model is able to reproduce the qualitative behaviour measured upon Nb-doped SrTiO$_3$ memristive devices. Our analysis demonstrates a direct correlation between the devices' characteristic parameters and those of our model. The model can clearly identify the charge transport mechanism in different resistive states thus facilitating evaluation of the relevant parameters pertaining to resistive switching in interface-based memristors. One clear application of our study is its ability to inform the design and fabrication of related memristive devices.Comment: 14 pages, 2 pages of Supplementary Data, 4 figures, 4 table

Body condition scoring of Bornean banteng in logged forests

© The Author(s) 2016. Background The Bornean banteng (Bos javanicus lowi) is an endangered subspecies that often inhabits logged forest; however very little is known about the effects of logging on their ecology, despite the differing effects this has on other ungulate species. A body condition scoring system was created for the Bornean banteng using camera trap photographs from five forests in Sabah, Malaysia, with various past and present management combinations to establish if banteng nutrition suffered as a result of forest disturbance. Results One hundred and eleven individuals were photographed over 38,009 camera trap nights from April 2011 to June 2014 in five forests. Banteng within forests that had a recent history of reduced-impact logging had higher body condition scores than banteng within conventionally logged forest. Conversely, when past logging was conducted using a conventional technique and the period of forest regeneration was relatively long; the banteng had higher body condition scores. Conclusion The body condition scoring system is appropriate for monitoring the long-term nutrition of the Bornean banteng and for evaluating the extent of the impact caused by present-day reduced-impact logging methods. Reduced-impact logging techniques give rise to individuals with the higher body condition scores in the shorter term, which then decline over time. In contrast the trend is opposite for conventional logging, which demonstrates the complex effects of logging on banteng body condition scores. This is likely to be due to differences in regeneration between forests that have been previously logged using differing methods

CP and related phenomena in the context of Stellar Evolution

We review the interaction in intermediate and high mass stars between their evolution and magnetic and chemical properties. We describe the theory of Ap-star `fossil' fields, before touching on the expected secular diffusive processes which give rise to evolution of the field. We then present recent results from a spectropolarimetric survey of Herbig Ae/Be stars, showing that magnetic fields of the kind seen on the main-sequence already exist during the pre-main sequence phase, in agreement with fossil field theory, and that the origin of the slow rotation of Ap/Bp stars also lies early in the pre-main sequence evolution; we also present results confirming a lack of stars with fields below a few hundred gauss. We then seek which macroscopic motions compete with atomic diffusion in determining the surface abundances of AmFm stars. While turbulent transport and mass loss, in competition with atomic diffusion, are both able to explain observed surface abundances, the interior abundance distribution is different enough to potentially lead to a test using asterosismology. Finally we review progress on the turbulence-driving and mixing processes in stellar radiative zones.Comment: Proceedings of IAU GA in Rio, JD4 on Ap stars; 10 pages, 7 figure

Cow responses and evolution of the rumen bacterial and methanogen community following a complete rumen content transfer

Understanding the rumen microbial ecosystem requires the identification of factors that influence the community structure, such as nutrition, physiological condition of the host and host-microbiome interactions. The objective of the current study was to describe the rumen microbial communities before, during and after a complete rumen content transfer. The rumen contents of one donor cow were removed completely and used as inoculum for the emptied rumen of the donor itself and three acceptor cows under identical physiological and nutritional conditions. Temporal changes in microbiome composition and rumen function were analysed for each of four cows over a period of 6 weeks. Shortly after transfer, the cows showed different responses to perturbation of their rumen content. Feed intake depression in the first 2 weeks after transfer resulted in short-term changes in milk production, methane emission, fatty acid composition and rumen bacterial community composition. These effects were more pronounced in two cows, whose microbiome composition showed reduced diversity. The fermentation metrics and microbiome diversity of the other two cows were not affected. Their rumen bacterial community initially resembled the composition of the donor but evolved to a new community profile that resembled neither the donor nor their original composition. Descriptive data presented in the current paper show that the rumen bacterial community composition can quickly recover from a reduction in microbiome diversity after a severe perturbation. In contrast to the bacteria, methanogenic communities were more stable over time and unaffected by stress or host effects