Simulation and Measurement of Pressure Rise in GIS 145 kV due to nternal Arcing

Internal arc testing of metal-enclosed, SF6 gas insulated switchgear (GIS) is defined by IEC 62271-203 and is not a part of mandatory type tests. However, due to the increasing demands on the safety of personnel, more often the implementation of this test is required in the tender documentation. According to IEC, the duration of the electric arc is related to the performance of the protective system determined by the first and second stage of protection. For the rated short-circuit current equal or higher than 40 kA, during the first stage of protection (0.1 s), no external effects on enclosure other than the operation of pressure relief device is permitted. During the second stage of protection (≤0.3 s) no fragmentation is permitted, but burn-through is acceptable. The test should be carried out on the GIS compartment with the smallest volume at nominal gas pressure. Since a newly developed GIS 145 kV is designed as a three-phase encapsulated, arc initiation is achieved by short connecting of all three phase conductors in the vicinity of a partition by means of a thin metal wire. This ensures that two electric arcs burn simultaneously commutating between the phases, so the possibility of enclosure burn-through in this type of GIS is minimized. In order to prevent the release of SF6 gas in the atmosphere during the testing, a test enclosure should be placed in a protective gastight enclosure filled with air or more often SF6 gas at pressure of 0.1 MPa. This test object configuration significantly complicates the pressure rise calculation and increases the testing cost. In order to prevent enclosure fragmentation, the pressure difference between the test enclosure and the protective enclosure during the test should always be less than the bursting pressure of test enclosure. Also, the protective enclosure should be designed to withstand the maximum pressure rise that may occur after pressure relief device opens. In order to assess the likelihood of passing the upcoming type test for newly developed GIS, a computer program for calculation of pressure and temperature in the test enclosure and protective enclosure was developed. The mathematical model is based on the paper of the working group CIGRE A3.24, published in 2014. The basic model shown in the paper is enhanced by the real properties of the SF6 gas/plasma, evaporation of the electrode material and the insulator ablation. The contribution of exothermic/endothermic reactions between the gas and the electrode material on the pressure and temperature rise was also considered. At the same time, the measurements of pressure rise in GIS enclosure and protective enclosure were carried out in Končar High Power Laboratory. The experiments performed on a copper and aluminum electrodes in SF6 gas confirmed significantly higher contribution of aluminum electrodes to the pressure and temperature rise compared to the copper electrodes. The computer program is verified by measurement results

The "K-Correction" for Irradiated Emission Lines in LMXBs: Evidence for a Massive Neutron Star in X1822-371 (V691 CrA)

We study the K-correction for the case of emission lines formed in the X-ray illuminated atmosphere of a Roche lobe filling star. We compute the K-correction as function of the mass ratio 'q' and the disc flaring angle 'alpha' using a compact binary code where the companion's Roche lobe is divided into 10^5 resolution elements. We also study the effect of the inclination angle in the results. We apply our model to the case of the neutron star low-mass X-ray binary X1822-371 (V691 CrA), where a K-emission velocity K_em=300 +-8 km/s has been measured by Casares et al. (2003). Our numerical results, combined with previous determination of system parameters, yields 1.61Msun < M_NS < 2.32Msun and 0.44Msun < M_2 < 0.56Msun for the two binary components(i. e. 0.24 < q < 0.27), which provide a compelling evidence for a massive neutron star in this system. We also discuss the implications of these masses into the evolutionary history of the binary.Comment: 6 pages, 5 figures. Accepted for publication in Ap

Mass Transfer by Stellar Wind

I review the process of mass transfer in a binary system through a stellar wind, with an emphasis on systems containing a red giant. I show how wind accretion in a binary system is different from the usually assumed Bondi-Hoyle approximation, first as far as the flow's structure is concerned, but most importantly, also for the mass accretion and specific angular momentum loss. This has important implications on the evolution of the orbital parameters. I also discuss the impact of wind accretion, on the chemical pollution and change in spin of the accreting star. The last section deals with observations and covers systems that most likely went through wind mass transfer: barium and related stars, symbiotic stars and central stars of planetary nebulae (CSPN). The most recent observations of cool CSPN progenitors of barium stars, as well as of carbon-rich post-common envelope systems, are providing unique constraints on the mass transfer processes.Comment: Chapter 7, in Ecology of Blue Straggler Stars, H.M.J. Boffin, G. Carraro & G. Beccari (Eds), Astrophysics and Space Science Library, Springe

A dual function TAR Decoy serves as an anti-HIV siRNA delivery vehicle

The TAR RNA of HIV was engineered as an siRNA delivery vehicle to develop a combinatorial therapeutic approach. The TAR backbone was found to be a versatile backbone for expressing siRNAs. Upon expression in human cells, pronounced and specific inhibition of reporter gene expression was observed with TARmiR. The resulting TARmiR construct retained its ability to bind Tat and mediate RNAi. TARmiR was able to inhibit HIV gene expression as a TAR decoy and by RNA interference when challenged with infectious proviral DNA. The implications of this dual function therapeutic would be discussed

The Evolution of Compact Binary Star Systems

We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure

Orbital Evolution of Algol Binaries with a Circumbinary Disk

It is generally thought that conservative mass transfer in Algol binaries causes their orbits to be wider, in which the less massive star overflows its Roche-lobe. The observed decrease in the orbital periods of some Algol binaries suggests orbital angular momentum loss during the binary evolution, and the magnetic braking mechanism is often invoked to explain the observed orbital shrinkage. Here we suggest an alternative explanation, assuming that a small fraction of the transferred mass forms a circumbinary disk, which extracts orbital angular momentum from the binary through tidal torques. We also perform numerical calculations of the evolution of Algol binaries with typical initial masses and orbital periods. The results indicate that, for reasonable input parameters, the circumbinary disk can significantly influence the orbital evolution, and cause the orbit to shrink on a sufficiently long timescale. Rapid mass transfer in Algol binaries with low mass ratios can also be accounted for in this scenario.Comment: 9 pages, 5 figures, accepted for publication in Ap

Beliefs and preferences regarding biological treatments for severe asthma

Background: Severe asthma is a serious condition with a significant burden on patients' morbidity, mortality, and quality of life. Some biological therapies targeting the IgE and interleukin-5 (IL5) mediated pathways are now available. Due to the lack of direct comparison studies, the choice of which medication to use varies. We aimed to explore the beliefs and practices in the use of biological therapies in severe asthma, hypothesizing that differences will occur depending on the prescribers’ specialty and experience. Methods: We conducted an online survey composed of 35 questions in English. The survey was circulated via the INterasma Scientific Network (INESNET) platform as well as through social media. Responses from allergists and pulmonologists, both those with experience of prescribing omalizumab with (OMA/IL5) and without (OMA) experience with anti-IL5 drugs, were compared. Results: Two hundred eighty-five (285) valid questionnaires from 37 countries were analyzed. Seventy-on percent (71%) of respondents prescribed biologics instead of oral glucocorticoids and believed that their side effects are inferior to those of Prednisone 5 mg daily. Agreement with ATS/ERS guidelines for identifying severe asthma patients was less than 50%. Specifically, significant differences were found comparing responses between allergists and pulmonologists (Chi-square test, p &lt; 0.05) and between OMA/IL5 and OMA groups (p &lt; 0.05). Conclusions: Uncertainties and inconsistencies regarding the use of biological medications have been shown. The accuracy of prescribers to correctly identify asthma severity, according to guidelines criteria, is quite poor. Although a substantial majority of prescribers believe that biological drugs are safer than low dose long-term treatment with oral steroids, and that they must be used instead of oral steroids, every effort should be made to further increase awareness. Efficacy as disease modifiers, biomarkers for selecting responsive patients, timing for outcomes evaluation, and checks need to be addressed by further research. Practices and beliefs regarding the use of asthma biologics differ between the prescriber's specialty and experience; however, the latter seems more significant in determining beliefs and behavior. Tailored educational measures are needed to ensure research results are better integrated in daily practice

BUILDING BRIDGES FOR INNOVATION IN AGEING : SYNERGIES BETWEEN ACTION GROUPS OF THE EIP ON AHA

The Strategic Implementation Plan of the European Innovation Partnership on Active and Healthy Ageing (EIP on AHA) proposed six Action Groups. After almost three years of activity, many achievements have been obtained through commitments or collaborative work of the Action Groups. However, they have often worked in silos and, consequently, synergies between Action Groups have been proposed to strengthen the triple win of the EIP on AHA. The paper presents the methodology and current status of the Task Force on EIP on AHA synergies. Synergies are in line with the Action Groups' new Renovated Action Plan (2016-2018) to ensure that their future objectives are coherent and fully connected. The outcomes and impact of synergies are using the Monitoring and Assessment Framework for the EIP on AHA (MAFEIP). Eight proposals for synergies have been approved by the Task Force: Five cross-cutting synergies which can be used for all current and future synergies as they consider overarching domains (appropriate polypharmacy, citizen empowerment, teaching and coaching on AHA, deployment of synergies to EU regions, Responsible Research and Innovation), and three cross-cutting synergies focussing on current Action Group activities (falls, frailty, integrated care and chronic respiratory diseases).Peer reviewe

Differentiation of COVID-19 signs and symptoms from allergic rhinitis and common cold: An ARIA-EAACI-GA2LEN consensus

Background: Although there are many asymptomatic patients, one of the problems of COVID-19 is early recognition of the disease. COVID-19 symptoms are polymorphic and may include upper respiratory symptoms. However, COVID-19 symptoms may be mistaken with the common cold or allergic rhinitis. An ARIA-EAACI study group attempted to differentiate upper respiratory symptoms between the three diseases. Methods: A modified Delphi process was used. The ARIA members who were seeing COVID-19 patients were asked to fill in a questionnaire on the upper airway symptoms of COVID-19, common cold and allergic rhinitis. Results: Among the 192 ARIA members who were invited to respond to the questionnaire, 89 responded and 87 questionnaires were analysed. The consensus was then reported. A two-way ANOVA revealed significant differences in the symptom intensity between the three diseases (p&nbsp;&lt;.001). Conclusions: This modified Delphi approach enabled the differentiation of upper respiratory symptoms between COVID-19, the common cold and allergic rhinitis. An electronic algorithm will be devised using the questionnaire