Constraints on the emission mechanisms of gamma-ray bursts

If the emission of gamma-ray bursts were due to the synchrotron process in the standard internal shock scenario, then the typical observed spectrum should have a slope F(nu) \propto nu^{-1/2}, which strongly conflicts with the much harder spectra observed. This directly follows from the cooling time being much shorter than the dynamical time. Particle re-acceleration, deviations from equipartition, fastly changing magnetic fields and adiabatic losses are found to be inadequate to account for this discrepancy. We also find that in the internal shock scenario the relativistic inverse Compton scattering is always as important as the synchrotron process, and faces the same problems. This indicates that the burst emission is not produced by relativistic electrons emitting synchrotron and inverse Compton radiation.Comment: 5 pages, accepted for publications in MNRAS, pink page

The polarisation of afterglow emission reveals GRB jet structure

We numerically compute light and polarisation curves of gamma-ray burst afterglows for various configurations of the jet luminosity structure and for different dynamical evolutions. We especially consider the standard homogeneous ``top hat'' jet and the ``universal structured jet'' with power-law wings. We also investigate a possible more physical variation of the ``top hat'' model: the ``Gaussian jet''. The polarisation curves for the last two jet types are shown here for the first time together with the computation of X-ray and radio polarised fluxes. We show that the lightcurves of the total flux from these configurations are very similar to each other, and therefore only very high quality data could allow us to pin down the underlying jet structure. We demonstrate instead that polarisation curves are a powerful means to solve the jet structure, since the predicted behaviour of polarisation and its position angle at times around the jet break are very different if not opposite. We conclude that the afterglow polarisation measurements provide clear footprints of any outflow energy distribution (unlike the lightcurves of the total flux) and the joint analysis of the total and polarised flux should reveal GRBs jet structure.Comment: 16 pages, 18 figures, MNRAS, temp, 321. Light curves and polarisation curves for a Gaussian jet added. Cartoon of the three jet structures adde

NURSES\u2019 INTERVENTIONS TO PROMOTE CANCER PATIENT ENGAGEMENT AND RELATED OUTCOMES: A SYSTEMATIC REVIEW AND META-ANALYSIS PROTOCOL

Background and aim of the work. Due to the ageing of cancer patients, new approaches that require a more active participation in the self-management of cancer treatment at home are needed. Nurses are strategic in improving the patient\u2019s engagement capability in this regard. Knowing which interventions are more effective for the promotion of patient engagement could be useful to improve the effectiveness of the care provided. Therefore, this study aims to systematically review nursing interventions or programs that promote patient engagement in oncological nursing care and summarizing the main evidence related to their impact on relevant clinical and psychosocial outcomes. Method. This is a systematic review and meta-analysis protocol based on Cochrane Handbook for the systematic review of interventions. We will search the most important electronic databases (PUBMED, CINAHL, EMBASE, SCOPUS, ISI Web of Science, Cochrane library) to find out which patient engagement interventions (active adult patient involvement) are implemented in oncological settings and understand what is the effectiveness of these interventions on the outcomes reported in the literature. The GRADE methodology will be used to synthetize the evidence. If possible, also a meta-analysis will be performed. We registered the study protocol on the PROSPERO database (N\ub0 CRD42020146189). Discussion and Conclusion. To our knowledge, this is the first systematic review to address this clinical question in the field of oncology. This review will offer health professionals indications on the most frequently adopted patient engagement interventions and verify their clinical effectiveness. Furthermore, any gaps in the scientific literature will be highlighted

Compton drag as a mechanism for very high linear polarization in Gamma-Ray Bursts

The recent claim by Coburn & Boggs to have detected a very high degree of linear polarization in the prompt emission of GRB 021206 has stimulated interest in how much polarization could arise in gamma-ray bursts from synchrotron emission. Alternatively, as Shaviv & Dar have shown, GRB polarization could be produced by inverse Compton scattering in the point-source limit. We discuss polarization from a fireball that upscatters a soft radiation field. We show that, after the proper angular integration, the residual polarization can be large, in some cases approaching the point-source limit. We discuss the probability of realizing the geometrical conditions in which a large polarization is obtained showing that, for a particularly bright burst as GRB 021206, the detection of polarization at the first attempt in the Compton drag scenario is not unlikely.Comment: Accepted for publication in MNRA

Jitter radiation images, spectra, and light curves from a relativistic spherical blastwave

We consider radiation emitted by the jitter mechanism in a Blandford-McKee self-similar blastwave. We assume the magnetic field configuration throughout the whole blastwave meets the condition for the emission of jitter radiation and we compute the ensuing images, light curves and spectra. The calculations are performed for both a uniform and a wind environment. We compare our jitter results to synchrotron results. We show that jitter radiation produces slightly different spectra than synchrotron, in particular between the self-absorption and the peak frequency, where the jitter spectrum is flat, while the synchrotron spectrum grows as \nu^{1/3}. The spectral difference is reflected in the early decay slope of the light curves. We conclude that jitter and synchrotron afterglows can be distinguished from each other with good quality observations. However, it is unlikely that the difference can explain the peculiar behavior of several recent observations, such as flat X-ray slopes and uncorrelated optical and X-ray behavior.Comment: 11 pages, 7 postscript figures. Accepted for publication in MNRA

Burnout precursors in oncology nurses: A preliminary cross-sectional study with a systemic organizational analysis

Burnout negatively affects nurses' health and performance. Healthcare managers have an ethical duty to create healthy organizations that reduce burnout, especially within critical settings such as oncology. The aim of this study was twofold: (1) to measure the presence of nurses' burnout to formulate organizational strategies to prevent the syndrome onset, and (2) to evaluate the effect of recent organizational changes on the burnout phenomenon. A descriptive, cross-sectional design supported by a systemic organizational analysis was conducted in a Swiss Oncology Institute in 2013. Of 103 nurses working in the Institute, 52 (51.4%) completed the Burnout Potential Inventory (BPI) questionnaire. Data were analyzed using descriptive statistics and Mann-Whitney and Kruskal-Wallis tests. Burnout risk levels were low to moderate. Only 2 nurses out of the 52 showed moderate burnout risk levels. Inpatient nurses showed a higher risk of burnout than outpatient nurses, particularly due to ambiguity and feelings of powerlessness. Nurses with post-basic education showed a higher risk when considering poor teamwork values and ambiguity in the workplace. Poor middle-management was found to negatively influence worker wellbeing. The working environment set by management resulted in low burnout risk levels. Managers must carefully select middle-management because inappropriate leadership might promote the onset of burnout

On the role of extinction in failed gamma-ray burst optical/IR afterglows

While all but one Gamma-Ray Bursts observed in the X-ray band showed an X-ray afterglow, about 60 per cent of them have not been detected in the optical band. We demonstrate that in many cases this is not due to adverse observing conditions, or delay in performing the observations. We also show that the optically non-detected afterglows are not affected by particularly large Galactic absorbing columns, since its distribution is similar for both the detected and non-detected burst subclasses. We then investigate the hypothesis that the failure of detecting the optical afterglow is due to absorption at the source location. We find that this is a marginally viable interpretation, but only if the X-ray burst and afterglow emission and the possible optical/UV flash do not destroy the dust responsible for absorption in the optical band. If dust is efficiently destroyed, we are led to conclude that bursts with no detected optical afterglow are intrinsically different. Prompt infrared observations are the key to solve this issue.Comment: Accepted for publication in MNRAS, changes in the tables and in the statistical analysi

Determining the location of Gamma-Ray Bursts through the evolution of their soft X-ray absorption

We investigate through dedicated numerical simulations the evolution of the soft X-ray absorption properties of a cloud surrounding a gamma-ray burst source. We show that the absorption properties of the material are strongly modified by the ionization induced by the intense burst flux. We derive the temporal evolution of the measured column density as a function of the density and size of the absorbing medium. Even if their statistical significance is not extremely compelling, we find that the detection in several bursts of variable absorption during the gamma-ray phase can be accounted for if these bursts are associated to overdense regions in molecular clouds with properties similar to those of star formation globules. We fit our model variable column density to the data of GRB 980329 and GRB 780506, showing that with this method the size, density and density distribution of the material surrounding a burst can be measured.Comment: 8 pages, 8 postscript figures, accepted for publication in MNRA

Jitter radiation in gamma-ray bursts and their afterglows: emission and self-absorption

Relativistic electrons moving into a highly tangled magnetic field emit jitter radiation. We present a detailed computation of the jitter radiation spectrum, including self-absorption, for electrons inside Weibel-like shock generated magnetic fields. We apply our results to the case of the prompt and afterglow emission of gamma-ray bursts. We show that jitter emission can reproduce most of the observed features with some important differences with respect to standard synchrotron, especially in the frequency range between the self-absorption and the peak frequency. We discuss the similarities and differences between jitter and synchrotron and discuss experiments that can disentangle the two mechanisms.Comment: 12 pages, 7 postscript figures. Figures, discussion, and references updated. Accepted for publication in MNRA