Managing ClientInitiated Connections

The Session Initiation Protocol (SIP) allows proxy servers to initiate TCP connections or to send asynchronous UDP datagrams to User Agents in order to deliver requests. However, in a large number of real deployments, many practical considerations, such as the existence of firewalls and Network Address Translators (NATs) or the use of TLS with server-provided certificates, prevent servers from connecting to User Agents in this way. This specification defines behaviors for User Agents, registrars, and proxy servers that allow requests to be delivered on existing connections established by the User Agent. It also defines keep-alive behaviors needed to keep NAT bindings open and specifies the usage of multiple connections from the User Agent to its registrar. Status of This Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards " (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as th

Optimization of laser-plasma injector via beam loading effects using ionization-induced injection

Simulations of ionization induced injection in a laser driven plasma wakefield show that high-quality electron injectors in the 50-200 MeV range can be achieved in a gas cell with a tailored density profile. Using the PIC code Warp with parameters close to existing experimental conditions, we show that the concentration of $\mathrm{N_2}$ in a hydrogen plasma with a tailored density profile is an efficient parameter to tune electron beam properties through the control of the interplay between beam loading effects and varying accelerating field in the density profile. For a given laser plasma configuration, with moderate normalized laser amplitude, $a_0=1.6$ and maximum electron plasma density, $n_{e0}=4\times 10^{18}\,\mathrm{cm^{-3}}$, the optimum concentration results in a robust configuration to generate electrons at 150~MeV with a rms energy spread of 4\% and a spectral charge density of 1.8~pC/MeV.Comment: 13 pages, 10 figure

Is the energy status influencing dispersion in American glass eel?

International audienceThe American eel has a facultative catadromous life cycle. Spawning occurs in Sargasso Sea and growth occurs into freshwater or saltwater habitats over a wide geographical range. The selection of suitable habitat for growth begins at the glass eel stage. Based on the hypothesis of conditional dispersion strategy, energetic status would determine whether glass eels would express freshwater or saltwater preference. Glass eels were captured from two rivers from Nova Scotia and two rivers from Québec in 2011 and 2012. Following salinity preference experiments, glass eels were classified as “inactive” or as “active with preference for fresh water” and “active with preference for salt water”. They were anaesthetized in MS 222, weighed, measured and frozen in carbonic ice. Results indicate that glass eels expressing preference for freshwater had the highest condition factor. Total content of glycogen and lipids were measured in order to test whether or not the three groups of glass eels could be differentiated based on their energy status whatever the river and the year of fishing and results will be presented

Investigation of the dynamics of ionization induced injected electrons under the influence of beam loading effects

In laser-driven wakefield, ionization induced injection is an efficient way to inject electrons in the plasma wave. A detailed study on the beam dynamics under the influence of beam loading effects, which can be controlled by the concentration of nitrogen impurity introduced in the hydrogen gas was conducted. For a specific value of this percentage, the final energy of the high-energy electron bunch becomes nearly independent of the trapped positions, thus leading to a small energy dispersion. We also show that the final beam emittance is mainly determined by the injection process

Occupational therapists’ views of using a virtual reality interior design application within the pre-discharge home visit process

This article has been made available through the Brunel Open Access Publishing Fund.Background: A key role of Occupational Therapists (OTs) is to carry out pre-discharge home visits (PHV) and propose appropriate adaptations to the home environment, to enable patients to function independently after hospital-home discharge. However, research shows that more than 50% of specialist equipment installed as part of home adaptations is not used by patients. A key reason for this is that decisions about home adaptations are often made without adequate collaboration and consultation with the patient. Consequently, there is an urgent need to seek out new and innovative uses of technology to facilitate patient/practitioner collaboration, engagement and shared decision making in the PHV process. Virtual reality interior design applications (VRIDAs) primarily allow users to simulate the home environment and visualise changes prior to implementing them. Customised VRIDAs, which also model specialist occupational therapy equipment, could become a valuable tool to facilitate improved patient/practitioner collaboration if developed effectively and integrated into the PHV process. Objective: To explore the perceptions of occupational therapists with regards to using VRIDAs as an assistive tool within the PHV process. Methods: Task-oriented interactive usability sessions, utilising the think-aloud protocol and subsequent semi-structured interviews were carried out with seven Occupational Therapists who possessed significant experience across a range of clinical settings. Template analysis was carried out on the think-aloud and interview data. Analysis was both inductive and driven by theory, centring around the parameters that impact upon the acceptance, adoption and use of this technology in practice as indicated by the Technology Acceptance Model (TAM). Results: OTs’ perceptions were identified relating to three core themes: (1) perceived usefulness (PU), (2) perceived ease of use (PEoU), and (3) actual use (AU). Regarding PU, OTs believed VRIDAs had promising potential to increase understanding, enrich communications and patient involvement, and improved patient/practitioner shared understanding. However, it was unlikely that VRIDAs would be suitable for use with cognitively impaired patients. For PEoU, all OTs were able to use the software and complete the tasks successfully, however, participants noted numerous specialist equipment items that could be added to the furniture library. AU perceptions were positive regarding use of the application across a range of clinical settings including children/young adults, long-term conditions, neurology, older adults, and social services. However, some “fine tuning” may be necessary if the application is to be optimally used in practice. Conclusions: Participants perceived the use of VRIDAs in practice would enhance levels of patient/practitioner collaboration and provide a much needed mechanism via which patients are empowered to become more equal partners in decisions made about their care. Further research is needed to explore patient perceptions of VRIDAs, to make necessary customisations accordingly, and to explore deployment of the application in a collaborative patient/practitioner-based context

Adapting an adherence support workers intervention: engaging traditional healers as adherence partners for persons enrolled in HIV care and treatment in rural Mozambique

Abstract Background Systematic adaptation of evidence-informed interventions that increase retention in care and improve adherence to antiretroviral therapy (ART) are essential to ending the HIV epidemic in rural sub-Saharan Africa. We selected and adapted an adherence support worker intervention employed in Malawi for use by traditional healers in rural Mozambique. Given the levels of trust and dependence previously expressed by persons living with HIV (PLHIV) for traditional medicine, we adapted the program to engage traditional healers within the allopathic health system. Methods Adaption followed a theoretically driven approach to intervention adaption: the Assessment-Decision-Administration-Production-Topical Experts-Integration-Training-Testing (ADAPT-ITT) model. Three rounds of performance feedback, based on theater presentations of the adapted intervention for stakeholders and idea generation, were completed with 12 groups from March to July 2016 to develop the final model. We offered healer support to 180 newly diagnosed HIV-infected patients. Results Traditional healers were an acceptable group of community health workers to assist with patient adherence and retention. Traditional healers, clinicians, and interested community members suggested novel strategies to tailor the adherence support worker intervention, revealing a local culture of HIV denialism, aversion to the health system, and dislike of healthcare providers, as well as a preference for traditional treatments. Proposed changes to the intervention included modifications to the training language and topics, expanded community-based activities to support acceptability of an HIV diagnosis and to facilitate partner disclosure, and accompaniment to the health facility by healers to encourage delivery of respectful clinical care. PLHIV, healers, and clinicians deemed the intervention socially acceptable during focus groups. We subsequently recruited 180 newly diagnosed HIV-infected patients into the program: 170 (94%) accepted. Conclusions Systematic translation of interventions, even between regions with similar social and economic environments, is an important first step to successful program implementation. Efforts previously limited to community health workers can be tailored for use by traditional healers—an underutilized and often maligned health workforce. It proved feasible to use theater-based performances to demonstrate delivery of the intervention in low-literacy populations, generating discussions about social norms, community concerns, and the merits of an acceptable strategy to improve retention and adherence to ART.https://deepblue.lib.umich.edu/bitstream/2027.42/136553/1/13012_2017_Article_582.pd

Generation of photoionized plasmas in the laboratory of relevance to accretion-powered x-ray sources using keV line radiation

We describe laboratory experiments to generate x-ray photoionized plasmas of relevance to accretion-powered x-ray sources such as neutron star binaries and quasars, with significant improvements over previous work. We refer to a key quantity, the photoionization parameter, defined as xi = 4{\pi}F/n_e where F is the x-ray flux and n_e the electron density. This is usually meaningful in a steady state context, but is commonly used, in the literature, as a figure of merit for laboratory experiments that are, of necessity, time dependent. We demonstrate that we can achieve values of xi >100 erg-cm s-1 using laser-plasma x-ray sources, in the regime of interest for several astrophysical scenarios. In particular, we show that our use of a keV line source, rather than the quasi-blackbody radiation fields normally employed in such experiments, has allowed generation of a ratio of inner-shell to outer-shell photoionization expected from a blackbody source with ~keV spectral temperature. This is a key factor in allowing experiments to be compared to the predictions of codes employed to model astrophysical sources. We compare calculations from our in-house plasma modelling code with those from Cloudy and find moderately good agreement for the time evolution of both electron temperature and average ionisation. However, a comparison of code predictions of a K-beta argon X-ray spectrum with experimental data reveals that our Cloudy simulation overestimates the intensities of more highly ionised argon species. This is not totally surprising as the Cloudy model was generated for a single set of plasma conditions, while the experimental data are spatially integrated.Comment: 20 pages, 9 figure

Objective and violation upper bounds on a DIRECT-filter method for global optimization

This paper addresses the problem of solving a constrained global optimization problem using a modification of the DIRECT method that incorporates the filter methodology to simultaneously minimize the objective function and the constraints violation. Thus, in the “Selection” step of the herein proposed DIRECT-filter algorithm, the hyperrectangles are classified in four categories and subsequently handled separately. The new algorithm also imposes upper bounds on the objective function and constraints violation aiming to discard some hyperrectangles from the process of identifying the potentially optimal ones. A heuristic to avoid the exploration of the hyperrectangles that have been mostly divided is also implemented. Preliminary numerical experiments are carried out to show the effectiveness of the imposed upper bounds on the objective and violation as well as the goodness of the heuristic.The authors wish to thank two anonymous referees for theircomments and suggestions to improve the paper. This work has been supported by FCT{ Fundação para a Ciência e Tecnologia within the Projects Scope: UID/CEC/00319/2019 and UID/MAT/00013/2013