On the evolution of eccentric and inclined protoplanets embedded in protoplanetary disks

Young planets embedded in their protoplanetary disk interact gravitationally with it leading to energy and angular momentum exchange. This interaction determines the evolution of the planet through changes to the orbital parameters. We investigate changes in the orbital elements of a 20 Earth--mass planet due to the torques from the disk. We focus on the non-linear evolution of initially non-vanishing eccentricity $e$ and/or inclination $i$. We treat the disk as a two- or three-dimensional viscous fluid and perform hydrodynamical simulations with an embedded planet. We find rapid exponential decay of the planet orbital eccentricity and inclination for small initial values of $e$ and $i$, in agreement with linear theory. For larger values of $e > 0.1$ the decay time increases and the decay rate scales as $\dot{e} \propto e^{-2}$, consistent with existing theoretical models. For large inclinations ($i$ > 6 deg) the inclination decay rate shows an identical scaling $di/dt \propto i^{-2}$. We find an interesting dependence of the migration on the eccentricity. In a disk with aspect ratio $H/r=0.05$ the migration rate is enhanced for small non-zero eccentricities ($e < 0.1$), while for larger values we see a significant reduction by a factor of $\sim 4$. We find no indication for a reversal of the migration for large $e$, although the torque experienced by the planet becomes positive when $e \simeq 0.3$. This inward migration is caused by the persisting energy loss of the planet. For non gap forming planets, eccentricity and inclination damping occurs on a time scale that is very much shorter than the migration time scale. The results of non linear hydrodynamic simulations are in very good agreement with linear theory for small $e$ and $i$.Comment: accepted for Astronomy & Astrophysics, 16 pages, 16 figures, animations under: http://www.tat.physik.uni-tuebingen.de/~kley/publ/paper/eccp.htm

A Super-Earth caught in a trap

This paper is an extension of the work done by Pierens & Nelson (2008) in which they have investigated the behaviour of a two-planet system embedded in a protoplanetary disc. They have put a Jupiter mass gas giant on the internal orbit and a lower mass planet on the external one. We consider here a similar problem taking into account a gas giant with masses in the range of 0.5 to 1 Jupiter mass and a Super-Earth as the outermost planet. By changing disc parameters and planet masses we have succeeded in getting the convergent migration which allows for the possibility of their resonant locking. However, in the case in which the gas giant has the mass of Jupiter, before any mean motion first order commensurability could be achieved, the Super-Earth is caught in a trap when it is very close to the edge of the gap opened by the giant planet. This confirms the result obtained by Pierens & Nelson (2008) in their simulations. Additionally, we have found that, in a very thin disc, an apsidal resonance is observed in the system if the Super-Earth is captured in the trap. Moreover, the eccentricity of the small planet remains low, while that of the gas giant increases slightly due to the imbalance between Lindblad and corotational resonances. We have also studied analogous systems in which the gas giant is allowed to take Sub-Jupiter masses. In this case, after performing an extensive survey over all possible parameters, we have succeeded in getting the 1:2 mean motion resonant configuration only in a disc with low aspect ratio and low surface density. However, the resonance is maintained just for few thousand orbits. Thus, we conclude that for typical protoplanetary discs the mean motion commensurabilities are rare if the Super-Earth is located on the external orbit relative to the gas giant. (abridged)Comment: 10 pages, 11 figures, accepted for publication in MNRA

Effects Of (R)-(-)-5-Methyl-1-Nicotinoyl-2-Pyrazoline On Glutamate Transporter 1 And Cysteine/Glutamate Exchanger As Well As Ethanol Drinking Behavior In Male, Alcohol-Preferring Rats

Alcohol consumption is largely associated with alterations in the extracellular glutamate concentrations in several brain reward regions. We recently showed that glutamate transporter 1 (GLT-1) is downregulated following chronic exposure to ethanol for 5 weeks in alcohol-preferring (P) rats and that upregulation of the GLT-1 levels in nucleus accumbens and prefrontal cortex results, in part, in attenuating ethanol consumption. Cystine glutamate antiporter (xCT) is also downregulated after chronic ethanol exposure in P rats, and its upregulation could be valuable in attenuating ethanol drinking. This study examines the effect of a synthetic compound, (R)-(−)-5-methyl-1-nicotinoyl-2-pyrazoline (MS-153), on ethanol drinking and expressions of GLT-1 and xCT in the amygdala and the hippocampus of P rats. P rats were exposed to continuous free-choice access to water, 15% and 30% ethanol, and food for 5 weeks, after which they received treatments of MS-153 or vehicle for 5 days. The results show that MS-153 treatment significantly reduces ethanol consumption. It was revealed that GLT-1 and xCT expressions were downregulated in both the amygdala and the hippocampus of ethanol–vehicle-treated rats (ethanol–vehicle group) compared with water-control animals. MS-153 treatment upregulated GLT-1 and xCT expressions in these brain regions. These findings demonstrate an important role for MS-153 in these glutamate transporters for the attenuation of ethanol-drinking behavior

Jet breaks at the end of the slow decline phase of Swift GRB lightcurves

The Swift mission has discovered an intriguing feature of Gamma-Ray Burst (GRBs) afterglows, a phase of shallow decline of the flux in the X-ray and optical lightcurves. This behaviour is typically attributed to energy injection into the burst ejecta. At some point this phase ends, resulting in a break in the lightcurve, which is commonly interpreted as the cessation of the energy injection. In a few cases, however, while breaks in the X-ray lightcurve are observed, optical emission continues its slow flux decline. This behaviour suggests a more complex scenario. In this paper, we present a model that invokes a double component outflow, in which narrowly collimated ejecta are responsible for the X-ray emission while a broad outflow is responsible for the optical emission. The narrow component can produce a jet break in the X-ray lightcurve at relatively early times, while the optical emission does not break due to its lower degree of collimation. In our model both components are subject to energy injection for the whole duration of the follow-up observations. We apply this model to GRBs with chromatic breaks, and we show how it might change the interpretation of the GRBs canonical lightcurve. We also study our model from a theoretical point of view, investigating the possible configurations of frequencies and the values of GRB physical parameters allowed in our model.Comment: 19 pages, 3 figures. To be published by MNRA

Disk eccentricity and embedded planets

We investigate the response of an accretion disk to the presence of a perturbing protoplanet embedded in the disk through time dependent hydrodynamical simulations. The disk is treated as a two-dimensional viscous fluid and the planet is kept on a fixed orbit. We run a set of simulations varying the planet mass, and the viscosity and temperature of the disk. All runs are followed until they reach a quasi-equilibrium state. We find that for planetary masses above a certain minimum mass, already 3 M_Jup for a viscosity of nu = 10^{-5}, the disk makes a transition from a nearly circular state into an eccentric state. Increasing the planetary mass leads to a saturation of disk eccentricity with a maximum value of around 0.25. The transition to the eccentric state is driven by the excitation of an m=2 spiral wave at the outer 1:3 Lindblad resonance. The effect occurs only if the planetary masses are large enough to clear a sufficiently wide and deep gap to reduce the damping effect of the outer 1:2 Lindblad resonance. An increase in viscosity and temperature in the disk, which both tend to close the gap, have an adverse influence on the disk eccentricity. In the eccentric state the mass accretion rate onto the planet is greatly enhanced, an effect that may ease the formation of massive planets beyond about 5 M_Jup that are otherwise difficult to reach.Comment: 9 Pages, 9 Figures, A&A in press, additional material under http://www.tat.physik.uni-tuebingen.de/~kley/publ/paper/eccdisk.htm

Interventions for improving medical students' interpersonal communication in medical consultations

Background Communication is a common element in all medical consultations, affecting a range of outcomes for doctors and patients. The increasing demand for medical students to be trained to communicate effectively has seen the emergence of interpersonal communication skills as core graduate competencies in medical training around the world. Medical schools have adopted a range of approaches to develop and evaluate these competencies. Objectives To assess the effects of interventions for medical students that aim to improve interpersonal communication in medical consultations. Search methods We searched five electronic databases: Cochrane Central Register of Controlled Trials, MEDLINE, Embase, PsycINFO, and ERIC (Educational Resource Information Centre) in September 2020, with no language, date, or publication status restrictions. We also screened reference lists of relevant articles and contacted authors of included studies. Selection criteria We included randomised controlled trials (RCTs), cluster‐RCTs (C‐RCTs), and non‐randomised controlled trials (quasi‐RCTs) evaluating the effectiveness of interventions delivered to students in undergraduate or graduate‐entry medical programmes. We included studies of interventions aiming to improve medical students’ interpersonal communication during medical consultations. Included interventions targeted communication skills associated with empathy, relationship building, gathering information, and explanation and planning, as well as specific communication tasks such as listening, appropriate structure, and question style. Data collection and analysis We used standard methodological procedures expected by Cochrane. Two review authors independently reviewed all search results, extracted data, assessed the risk of bias of included studies, and rated the quality of evidence using GRADE. Main results We found 91 publications relating to 76 separate studies (involving 10,124 students): 55 RCTs, 9 quasi‐RCTs, 7 C‐RCTs, and 5 quasi‐C‐RCTs. We performed meta‐analysis according to comparison and outcome. Among both effectiveness and comparative effectiveness analyses, we separated outcomes reporting on overall communication skills, empathy, rapport or relationship building, patient perceptions/satisfaction, information gathering, and explanation and planning. Overall communication skills and empathy were further divided as examiner‐ or simulated patient‐assessed. The overall quality of evidence ranged from moderate to very low, and there was high, unexplained heterogeneity. Overall, interventions had positive effects on most outcomes, but generally small effect sizes and evidence quality limit the conclusions that can be drawn. Communication skills interventions in comparison to usual curricula or control may improve both overall communication skills (standardised mean difference (SMD) 0.92, 95% confidence interval (CI) 0.53 to 1.31; 18 studies, 1356 participants; I² = 90%; low‐quality evidence) and empathy (SMD 0.64, 95% CI 0.23 to 1.05; 6 studies, 831 participants; I² = 86%; low‐quality evidence) when assessed by experts, but not by simulated patients. Students’ skills in information gathering probably also improve with educational intervention (SMD 1.07, 95% CI 0.61 to 1.54; 5 studies, 405 participants; I² = 78%; moderate‐quality evidence), but there may be little to no effect on students' rapport (SMD 0.18, 95% CI ‐0.15 to 0.51; 9 studies, 834 participants; I² = 81%; low‐quality evidence), and effects on information giving skills are uncertain (very low‐quality evidence). We are uncertain whether experiential interventions improve overall communication skills in comparison to didactic approaches (SMD 0.08, 95% CI ‐0.02 to 0.19; 4 studies, 1578 participants; I² = 4%; very low‐quality evidence). Electronic learning approaches may have little to no effect on students’ empathy scores (SMD ‐0.13, 95% CI ‐0.68 to 0.43; 3 studies, 421 participants; I² = 82%; low‐quality evidence) or on rapport (SMD 0.02, 95% CI ‐0.33 to 0.38; 3 studies, 176 participants; I² = 19%; moderate‐quality evidence) compared to face‐to‐face approaches. There may be small negative effects of electronic interventions on information giving skills (low‐quality evidence), and effects on information gathering skills are uncertain (very low‐quality evidence). Personalised/specific feedback probably improves overall communication skills to a small degree in comparison to generic or no feedback (SMD 0.58, 95% CI 0.29 to 0.87; 6 studies, 502 participants; I² = 56%; moderate‐quality evidence). There may be small positive effects of personalised feedback on empathy and information gathering skills (low quality), but effects on rapport are uncertain (very low quality), and we found no evidence on information giving skills. We are uncertain whether role‐play with simulated patients outperforms peer role‐play in improving students’ overall communication skills (SMD 0.17, 95% CI ‐0.33 to 0.67; 4 studies, 637 participants; I² = 87%; very low‐quality evidence). There may be little to no difference between effects of simulated patient and peer role‐play on students' empathy (low‐quality evidence) with no evidence on other outcomes for this comparison. Descriptive syntheses of results that could not be included in meta‐analyses across outcomes and comparisons were mixed, as were effects of different interventions and comparisons on specific communication skills assessed by the included trials. Quality of evidence was downgraded due to methodological limitations across several risk of bias domains, high unexplained heterogeneity, and imprecision of results. In general, results remain consistent in sensitivity analysis based on risk of bias and adjustment for clustering. No adverse effects were reported. Authors' conclusions This review represents a substantial body of evidence from which to draw, but further research is needed to strengthen the quality of the evidence base, to consider the long‐term effects of interventions on students’ behaviour as they progress through training and into practice, and to assess effects of interventions on patient outcomes. Efforts to standardise assessment and evaluation of interpersonal skills will strengthen future research efforts

Challenging GRB models through the broadband dataset of GRB060908

Context: Multiwavelength observations of gamma-ray burst prompt and afterglow emission are a key tool to disentangle the various possible emission processes and scenarios proposed to interpret the complex gamma-ray burst phenomenology. Aims: We collected a large dataset on GRB060908 in order to carry out a comprehensive analysis of the prompt emission as well as the early and late afterglow. Methods: Data from Swift-BAT, -XRT and -UVOT together with data from a number of different ground-based optical/NIR and millimeter telescopes allowed us to follow the afterglow evolution from about a minute from the high-energy event down to the host galaxy limit. We discuss the physical parameters required to model these emissions. Results: The prompt emission of GRB060908 was characterized by two main periods of activity, spaced by a few seconds of low intensity, with a tight correlation between activity and spectral hardness. Observations of the afterglow began less than one minute after the high-energy event, when it was already in a decaying phase, and it was characterized by a rather flat optical/NIR spectrum which can be interpreted as due to a hard energy-distribution of the emitting electrons. On the other hand, the X-ray spectrum of the afterglow could be fit by a rather soft electron distribution. Conclusions: GRB060908 is a good example of a gamma-ray burst with a rich multi-wavelength set of observations. The availability of this dataset, built thanks to the joint efforts of many different teams, allowed us to carry out stringent tests for various interpretative scenarios showing that a satisfactorily modeling of this event is challenging. In the future, similar efforts will enable us to obtain optical/NIR coverage comparable in quality and quantity to the X-ray data for more events, therefore opening new avenues to progress gamma-ray burst research.Comment: A&A, in press. 11 pages, 5 figure

PReSaFe: : a model of barriers and facilitators to patients providing feedback on experiences of safety

Objective - The importance of involving patients in reporting on safety is increasingly recognized. Whilst studies have identified barriers to clinician incident reporting, few have explored barriers and facilitators to patient reporting of safety experiences. This paper explores patient perspectives on providing feedback on safety experiences. Design/Participants - Patients (n=28) were invited to take part in semi-structured interviews when given a survey about their experiences of safety following hospital discharge. Transcripts were thematically analysed using NVivo10. Setting - Patients were recruited from four hospitals in the UK. Results - Three themes were identified as barriers and facilitators to patient involvement in providing feedback on their safety experiences. The first, cognitive-cultural, found that whilst safety was a priority for most, some felt the term was not relevant to them because safety was the “default” position, and/or because safety could not be disentangled from the overall experience of care. The structural-procedural theme indicated that reporting was facilitated when patients saw the process as straightforward, but that disinclination or perceived inability to provide feedback was a barrier. Finally, learning and change illustrated that perception of the impact of feedback could facilitate or inhibit reporting. Conclusions - When collecting patient feedback on experiences of safety, it is important to consider what may help or hinder this process, beyond the process alone. We present a staged model of prerequisite barriers and facilitators and hypothesize that each stage needs to be achieved for patients to provide feedback on safety experiences. Implications for collecting meaningful data on patients' safety experiences are considered

Ethanol-Associated Changes in Glutamate Reward Neurocircuitry: A Minireview of Clinical and Preclinical Genetic Findings

Herein, we have reviewed the role of glutamate, the major excitatory neurotransmitter in the brain, in a number of neurochemical, -physiological, and -behavioral processes mediating the development of alcohol dependence. The findings discussed include results from both preclinical as well as neuroimaging and postmortem clinical studies. Expression levels for a number of glutamate-associated genes and/or proteins are modulated by alcohol abuse and dependence. These changes in expression include metabotropic receptors and ionotropic receptor subunits as well as different glutamate transporters. Moreover, these changes in gene expression parallel the pharmacologic manipulation of these same receptors and transporters. Some of these gene expression changes may have predated alcohol abuse and dependence because a number of glutamate-associated polymorphisms are related to a genetic predisposition to develop alcohol dependence. Other glutamate-associated polymorphisms are linked to age at the onset of alcohol-dependence and initial level of response/sensitivity to alcohol. Finally, findings of innate and/or ethanol-induced glutamate-associated gene expression differences/changes observed in a genetic animal model of alcoholism, the P rat, are summarized. Overall, the existing literature indicates that changes in glutamate receptors, transporters, enzymes, and scaffolding proteins are crucial for the development of alcohol dependence and there is a substantial genetic component to these effects. This indicates that continued research into the genetic underpinnings of these glutamate-associated effects will provide important novel molecular targets for treating alcohol abuse and dependence

REM observations of GRB060418 and GRB060607A: the onset of the afterglow and the initial fireball Lorentz factor determination

Context. Gamma-ray burst (GRB) emission is believed to originate in highly relativistic fireballs. Aims. Currently, only lower limits were securely set to the initial fireball Lorentz factor Γο. We aim to provide a direct measure of Γο. Methods. The early-time afterglow light curve carries information about Γο, which determines the time of the afterglow peak. We have obtained early observations of the near-infrared afterglows of GRB 060418 and GRB 060607A with the REM robotic telescope. Results. For both events, the afterglow peak could be clearly singled out, allowing a firm determination of the fireball Lorentz of Γο ~400, fully confirming the highly relativistic nature of GRB fireballs. The deceleration radius was inferred to be R[dec] ≈ 10¹⁷ cm. This is much larger than the internal shocks radius (believed to power the prompt emission), thus providing further evidence for a different origin of the prompt and afterglow stages of the GRB