Evidence for virtual Compton scattering from the proton

In virtual Compton scattering an electron is scattered off a nucleon such that the nucleon emits a photon. We show that these events can be selected experimentally, and present the first evidence for virtual Compton scattering from the proton in data obtained at the Stanford Linear Accelerator Center. The angular and energy dependence of the data is well described by a calculation that includes the coherent sum of electron and proton radiation

Astronomical Distance Determination in the Space Age: Secondary Distance Indicators

The formal division of the distance indicators into primary and secondary leads to difficulties in description of methods which can actually be used in two ways: with, and without the support of the other methods for scaling. Thus instead of concentrating on the scaling requirement we concentrate on all methods of distance determination to extragalactic sources which are designated, at least formally, to use for individual sources. Among those, the Supernovae Ia is clearly the leader due to its enormous success in determination of the expansion rate of the Universe. However, new methods are rapidly developing, and there is also a progress in more traditional methods. We give a general overview of the methods but we mostly concentrate on the most recent developments in each field, and future expectations. © 2018, The Author(s)

Ground-based and JWST observations of SN 2022pul. I. Unusual signatures of carbon, oxygen, and circumstellar interaction in a peculiar type Ia supernova

Nebular-phase observations of peculiar Type Ia supernovae (SNe Ia) provide important constraints on progenitor scenarios and explosion dynamics for both these rare SNe and the more common, cosmologically useful SNe Ia. We present observations from an extensive ground- and space-based follow-up campaign to characterize SN 2022pul, a super-Chandrasekhar mass SN Ia (alternatively "03fg-like" SN), from before peak brightness to well into the nebular phase across optical to mid-infrared (MIR) wavelengths. The early rise of the light curve is atypical, exhibiting two distinct components, consistent with SN Ia ejecta interacting with dense carbon–oxygen (C/O)-rich circumstellar material (CSM). In the optical, SN 2022pul is most similar to SN 2012dn, having a low estimated peak luminosity (MB = −18.9 mag) and high photospheric velocity relative to other 03fg-like SNe. In the nebular phase, SN 2022pul adds to the increasing diversity of the 03fg-like subclass. From 168 to 336 days after peak B-band brightness, SN 2022pul exhibits asymmetric and narrow emission from [O i] λλ6300, 6364 (FWHM ≈ 2000 km s−1), strong, broad emission from [Ca ii] λλ7291, 7323 (FWHM ≈ 7300 km s−1), and a rapid Fe iii to Fe ii ionization change. Finally, we present the first ever optical-to-MIR nebular spectrum of an 03fg-like SN Ia using data from JWST. In the MIR, strong lines of neon and argon, weak emission from stable nickel, and strong thermal dust emission (with T ≈ 500 K), combined with prominent [O i] in the optical, suggest that SN 2022pul was produced by a white dwarf merger within C/O-rich CSM

Assessment of automated multitemporal image co-registration using repeat station imaging techniques

Repeat station imaging (RSI) is a method for specialized image collection and co-registration that facilitates rapid change detection with aerial imagery for time-critical analyses. Our previously reported research has defined methods for automated multitemporal image co-registration and demonstrated the utility of RSI for achieving precise co-registration, but without actually automating the technique. For this paper, we developed a custom software implementing specific procedures for automated RSI-based image co-registration, processed 252 image pairs containing diverse scenes and collection conditions, and evaluated the performance of RSI and the auto-registration tool. We found that the average root-mean-square error of image co-registration ranged between 1.3 and 1.9 pixels for aerial RSI images with 8–14 cm spatial resolution captured at the same time of day. The implications of these findings are that automated multitemporal co-registration and automated change detection could be performed in near real-time onboard an aircraft as it flies, opening up a range of new monitoring applications, particularly with unmanned aircraft systems. However, results with our custom software also indicate that images captured at different times of day with varying illumination and shadow conditions yield poor co-registration, and in some instances fail to register

Reflections on delivering a cross-discipline, cross-cultural, international, masters-level collaborative course using e-Learning technologies

This paper presents a case study on the experience of delivering an Internet-based international collaborative semester course at intermediate postgraduate level and attempts to distill a model for exploring the success factors involved when presenting such courses. The pedagogic and practical implications in terms of the effectiveness of the technological and system administrative choices made for delivering the course content and facilitating team interaction is evaluated. The structure and contents of the course are considered in light of the focus on innovation within the development of novel ubiquitous products and services. Furthermore the synchronous nature of the real time collaboration tools employed are contrasted with asynchronous alternatives given that the participating countries are highly distributed according to longitude and diverse according to their native language, cultural customs and technical skill set. A survey of extant technologies employable in facilitating such courses is presented together with an analysis of the criteria necessary to facilitate a successful delivery of the course. The institutional needs of security and management of its ICS resources are placed in the context of the effective administration of such a course given the highly heterogeneous selection of technologies employed. The contrast of the available resources of the only first world participant, functioning also as the virtual host (the Netherlands), with the remainder of the consortium is made in terms of technological and communication constraints. The problem is then modelled as a multi-agent collaborative communication problem in which participants are represented by proxy agents within a virtual environment. Multi-agency is selected as a framework for analysing the problem domain due to its strong theoretical underpinnings in computer science, economics and other fields. Each agent attempts to maximise its own utility function value based on its ability to solve sub-tasks assigned to it coupled with their contribution to the global utility for the agent’s team. Communication channels exists between agents, vary in terms of their availability over time and are not uniformly distributed between agents. Furthermore such channels may be classed as either synchronous or asynchronous. Likewise in order to model the cross-disciplinary nature of the course each task requires certain competencies to be completed effectively, these competencies are not uniformly distributed amongst the agents. To model differences in time zones each agent's cognitive capacity also varies according to a time based function and point of origin. This model is formalised using standard software engineering modelling languages and salient aspects implemented using standard agent oriented development frameworks. Although the system models a collaboration the reality of such interactions are that agents are inherently self-interested. Due to this, the model allows for differing task allocation strategies to be employed and the emergent effects of policies such as egalitarian, meritocratic and historical performance based distribution schemes to be compared. The end result of this modelling activity is to establish the most favourable mix of communication channels which would need to be provided for a given globally distributed team composition. The model may also be used to explore the most favourable policy-mix from an institution's point of view in order to facilitate such collaborations while maintaining an adequate level of security.Design EngineeringIndustrial Design Engineerin

Vaginectomy in Transmasculine Patients: A Review of Techniques in an Emerging Field

Purpose This report reviews the various techniques for vaginal obliterative surgery in the transmasculine patient population, including advantages and drawbacks with differing methods and reflects on the focus of future research and surgical efforts. Findings Existing techniques for vaginal obliterative surgery by vaginectomy or colpocleisis vary without strong evidence to identify a superior approach. Summary The increasing number of transmasculine patients seeking vaginectomy as a part of gender-affirming surgery must be matched by evidence-based techniques that provide a safe, long-term outcome. </jats:sec

Comparing inclination dependent analyses of kilonova transients

International audienceThe detection of the optical transient AT2017gfo proved that binary neutron star mergers are progenitors of kilonovae (KNe). Using a combination of numerical-relativity and radiative-transfer simulations, the community has developed sophisticated models for these transients for a wide portion of the expected parameter space. Using these simulations and surrogate models made from them, it has been possible to perform Bayesian inference of the observed signals to infer properties of the ejected matter. It has been pointed out that combining inclination constraints derived from the KN with gravitational-wave measurements increases the accuracy with which binary parameters can be estimated, in particular breaking the distance-inclination degeneracy from gravitational wave inference. To avoid bias from the unknown ejecta geometry, constraints on the inclination angle for AT2017gfo should be insensitive to the employed models. In this work, we compare different assumptions about the ejecta and radiative reprocesses used by the community and we investigate their impact on the parameter inference. While most inferred parameters agree, we find disagreement between posteriors for the inclination angle for different geometries that have been used in the current literature. According to our study, the inclusion of reprocessing of the photons between different ejecta types improves the modeling fits to AT2017gfo and, in some cases, affects the inferred constraints. Our study motivates the inclusion of large ∼ 1-mag uncertainties in the KN models employed for Bayesian analysis to capture yet unknown systematics, especially when inferring inclination angles, although smaller uncertainties seem appropriate to capture model systematics for other intrinsic parameters. We can use this method to impose soft constraints on the ejecta geometry of the KN AT2017gfo

Changing professional practice in tuberculosis care: an educational intervention.

AIM: This paper describes the development and implementation of an experiential, participatory in-service education programme focusing on patient-centeredness, problem-solving and critical reflection for primary providers delivering care to tuberculosis patients in South Africa. BACKGROUND: Tuberculosis is a major contributor to the disease burden in developing countries. In South Africa, approximately 90% of tuberculosis patients are managed by nurses at the primary level. Despite efforts to improve quality of care for these patients, many fail to complete their treatment as prescribed. Poor rapport between health care providers and patients with tuberculosis is a major reason for non-adherence to treatment. Methods of improving the quality of care delivery and communication between health care providers and patients with tuberculosis is therefore a priority. DISCUSSION: The paper outlines the stages of developing and implementing the education programme and reflects on this process. Data is drawn from an in-depth qualitative evaluation of the delivery and impacts of the intervention. The approach was acceptable to health care providers and adaptable to the needs of specific clinics. Participants evaluated the educational intervention positively, noting that it facilitated critical reflection on their work; encouraged problem-solving; and heightened their awareness of communication with patients and with colleagues. However, important structural barriers to practice change were identified, including conditions of service, relations with colleagues and support from management. CONCLUSIONS: Experiential, participatory in-service education can be implemented on a large scale in primary care settings. However, the process is resource intensive and the impacts of such education may be limited by barriers at other levels of the health system