Nonperturbative calculation of Born-Infeld effects on the Schroedinger spectrum of the hydrogen atom

We present the first nonperturbative numerical calculations of the nonrelativistic hydrogen spectrum as predicted by first-quantized electrodynamics with nonlinear Maxwell-Born-Infeld field equations. We also show rigorous upper and lower bounds on the ground state. When judged against empirical data our results significantly restrict the range of viable values of the new electromagnetic constant which is introduced by the Born-Infeld theory. We assess Born's own proposal for the value of his constant.Comment: 4p., 2 figs, 1 table; submitted for publicatio

Variable emission mechanism of a Type IV radio burst

Context. The Sun is an active star and the source of the largest explosions in the solar system, such as flares and coronal mass ejections (CMEs). Flares and CMEs are powerful particle accelerators that can generate radio emission through various emission mechanisms. Aims. CMEs are often accompanied by Type IV radio bursts that are observed as continuum emission in dynamic spectra at decimetric and metric wavelengths, but their emission mechanism can vary from event to event. Here, we aim to determine the emission mechanism of a complex Type IV burst that accompanied the flare and CME on 22 September 2011. Methods. We used radio imaging from the Nancay Radioheliograph, spectroscopic data from the e-Callisto network, ARTEMIS, Ondrejov, and Phoenix3 spectrometers combined with extreme-ultraviolet observations from NASA's Solar Dynamic Observatory to analyse the Type IV radio burst and determine its emission mechanism. Results. We show that the emission mechanism of the Type IV radio burst changes over time. We identified two components in the Type IV radio burst: an earlier stationary Type IV showing gyro-synchrotron behaviour, and a later moving Type IV burst covering the same frequency band. This second component has a coherent emission mechanism. Fundamental plasma emission and the electron-cyclotron maser emission are further investigated as possible emission mechanisms for the generation of the moving Type IV burst. Conclusions. Type IV bursts are therefore complex radio bursts, where multiple emission mechanisms can contribute to the generation of the wide-band continuum observed in dynamic spectra. Imaging spectroscopy over a wide frequency band is necessary to determine the emission mechanisms of Type IV bursts that are observed in dynamic spectra.Peer reviewe

STELLAR : a EU twinning project on LOFAR data analysis and knowledge transfer

The Scientific and Technological Excellence by Leveraging LOFAR Advancements in Radio Astronomy (STELLAR) is a project of mutual collaboration and know-how transfer in the field of radio astronomy, solar physics and space weather using the LOFAR instrument and data. Two institutions from Bulgaria, benefit from technical and scientific know-how exchange from world- leading RA institutions - ASTRON (the Netherlands) and DIAS (Ireland) via series of training hands-on sessions, workshops, seminars and project-focused schools for both students and senior staff. The poster presents the activities so far and future plans. All results, links to videos and outreach activities are hosted at a dedicated web-site. The STELLAR project is funded by the European Union's Horizon 2020 research and innovation programme under grant agreement No 952439. It is coordinated by the Institute of Astronomy, Bulgarian Academy of Sciences

Loss-cone instability modulation due to a magnetohydrodynamic sausage mode oscillation in the solar corona

Solar flares often involve the acceleration of particles to relativistic energies and the generation of high-intensity bursts of radio emission. In some cases, the radio bursts can show periodic or quasiperiodic intensity pulsations. However, precisely how these pulsations are generated is still subject to debate. Prominent theories employ mechanisms such as periodic magnetic reconnection, magnetohydrodynamic (MHD) oscillations, or some combination of both. Here we report on high-cadence (0.25 s) radio imaging of a 228 MHz radio source pulsating with a period of 2.3 s during a solar flare on 2014-April-18. The pulsating source is due to an MHD sausage mode oscillation periodically triggering electron acceleration in the corona. The periodic electron acceleration results in the modulation of a loss-cone instability, ultimately resulting in pulsating plasma emission. The results show that a complex combination of MHD oscillations and plasma instability modulation can lead to pulsating radio emission in astrophysical environments.Peer reviewe

Observations of Low Frequency Solar Radio Bursts from the Rosse Solar-Terrestrial Observatory

The Rosse Solar-Terrestrial Observatory (RSTO; www.rosseobservatory.ie) was established at Birr Castle, Co. Offaly, Ireland (53 05'38.9", 7 55'12.7") in 2010 to study solar radio bursts and the response of the Earth's ionosphere and geomagnetic field. To date, three Compound Astronomical Low-cost Low-frequency Instrument for Spectroscopy and Transportable Observatory (CALLISTO) spectrometers have been installed, with the capability of observing in the frequency range 10-870 MHz. The receivers are fed simultaneously by biconical and log-periodic antennas. Nominally, frequency spectra in the range 10-400 MHz are obtained with 4 sweeps per second over 600 channels. Here, we describe the RSTO solar radio spectrometer set-up, and present dynamic spectra of a sample of Type II, III and IV radio bursts. In particular, we describe fine-scale structure observed in Type II bursts, including band splitting and rapidly varying herringbone features

LOFAR tied-array imaging of Type III solar radio bursts

Context. The Sun is an active source of radio emission which is often associated with energetic phenomena such as solar flares and coronal mass ejections (CMEs). At low radio frequencies (< 100 MHz), the Sun has not been imaged extensively because of

Prospective Telehealth Analysis of Functional Performance, Frailty, Quality of Life, and Mental Health after COVID-19 hospitalization

Background COVID-19 is a global pandemic with poorly understood long-term consequences. Determining the trajectory of recovery following COVID-19 hospitalization is critical for prioritizing care, allocating resources, facilitating prognosis, and informing rehabilitation. The purpose of this study was to prospectively evaluate recovery following COVID-19 hospitalization. Methods Participants age 18 years or older who were hospitalized for ≥24 h due to COVID-19 completed phone/video call virtual assessments (including the 10-time chair rise test) and survey forms at three time points (2–6, 12, and 18 weeks) after hospital discharge. Univariate logistic and linear regression models assessed the associations of the outcomes with primary predictors (categorical age, sex, race/ethnicity group, and categorical pre-hospitalization frailty) at baseline; the same were used to assess differences in change from week 2–6 (continuous outcomes) or outcome persistence/worsening (categorical) at last contact. Results One hundred nine adults (age 53.0 [standard deviation 13.1]; 53% female) participated including 43 (39%) age 60 or greater; 59% identified as an ethnic and/or racial minority. Over 18 weeks, the mean time to complete the 10-time chair rise test decreased (i.e., improved) by 6.0 s (95% CI: 4.1, 7.9 s; p \u3c 0.001); this change did not differ by pre-hospital frailty, race/ethnicity group, or sex, but those age ≥ 60 had greater improvement. At weeks 2–6, 67% of participants reported a worse Clinical Frailty Scale category compared to their pre-hospitalization level, whereas 42% reported a worse frailty score at 18 weeks. Participants who did not return to pre-hospitalization levels were more likely to be female, younger, and report a pre-hospitalization category of ‘very fit’ or ‘well’. Conclusions We found that functional performance improved from weeks 2–6 to 18 weeks of follow-up; that incident clinical frailty developed in some individuals following COVID-19; and that age, sex, race/ethnicity, and pre-hospitalization frailty status may impact recovery from COVID-19. Notably, individuals age 60 and older were more likely than those under age 45 years to return to their pre-hospitalization status and to make greater improvements in functional performance. The results of the present study provide insight into the trajectory of recovery among a representative cohort of individuals hospitalized due to COVID-19. Background Coronavirus disease (COVID)-19 is a global pandemic with poorly understood long-term consequences. Recent data suggest that even mild cases of COVID-19 can result in significant long-term morbidity [1]. Determining the trajectory of recovery in patients following COVID-19 hospitalization is critical for prioritizing care, allocating resources, facilitating prognosis, and informing rehabilitation

A tale of two cities: A study of access to food, lessons for public health practice

Objectives: To map food access in the city of Preston in the north-west of England in order to determine access, availability and affordability of healthy food options. Design and methodology: The research design employed a number of distinct methods including: surveys of shops; interviews with local people and shopkeepers; a cost and availability survey of shops in two deprived areas of Preston —Deepdale and Ingol — the former with a majority South Asian population; and the use of geographical information systems to map access and availability. Results: • Preston had more fast food outlets (186) [not including restaurants who operate takeaways] than general groceries outlets (165). • There were more local shops selling affordable food in the area with the high South Asian population than in Ingol with its white working class population. There were clear gaps in provision and access in the white working class area (Ingol), with shops being more than 500 metres away from where people lived. Shops in this area stocked more familiar ‘British foods’ and less specialist or fresh produce. • Analysis of the availability of some healthy options such as brown bread, wholemeal pasta and brown rice showed that they were not widely available within shops in the two areas. • The price of the ‘White British’ basket in Ingol was £70.61 (cheapest price). For comparable goods in Deepdale, using the most expensive shopping basket, the price for the same basket was £42.47. • A South Asian family shopping at a major national supermarket outlet in Deepdale would pay £47.05. Using local shops they could pay between £38.59 and £44.28 by seeking out the best bargains in five shops (including some top-up items from a national supermarket). • At the time of the research a mother with two children, entitled to income support and child allowance, would have to spend 28—32 per cent of her income in local shops and 34 per cent in a supermarket to buy a basket of healthy goods. Conclusions: There is a need to engage proactively with the location of shops in urban areas, to ensure they offer a healthy range of options and are sited near to where people live. The number of fast food outlets needs to be controlled and the food they offer improved.This latter issue of the number of outlets and quality of fast food contributes to an overall obesogenic environment. Access to food is heavily dependent on having access to a car; local shopping and the quality of food on offer are important for key groups such as those on benefits, the elderly, single parents and others with limited access to a car. Proactive policy solutions may lie with the engagement of health agencies with the planning processes in local authorities to ensure that the food retail environment reflects a healthy choice. Local area agreements between health agencies and local authorities offer a way forward, in that they can take into account the expressed needs of local residents

Mind the gap? The persistence of pathological discourses in urban regeneration policy

Urban regeneration policy has historically framed policy problems using a discourse that pathologises areas and spatial communities. Since 2001 in England, and 2002 in Scotland a structural change in policy has occurred where citywide partnerships are now meant overcome structural spatial inequalities, countering pathological explanations. This paper uses historical and discourse analysis to evaluate one of the major community regeneration strategies developed by the Scottish Executive in 2002: Better Communities in Scotland: Closing the Gap. It seeks to ask whether structural change in policy was paralleled by discursive change; what discursive path dependence is evidenced? The text is placed in the historic context of UK urban renewal policies dating back to the launch of the Urban Programme in 1968 and particularly the policy discourse created by the influential Conservative government policy of 1988 New Life for Urban Scotland and the wider discourses of poverty and neighbourhood renewal policy created by Labour governments since 1997. The close textual analysis of the text shows that Better Communities in Scotland continues to pathologise spatial communities. Although this suggests a degree of historical path dependency, the historic breadth of the analysis also problematises simple historical determinism