Search for magnetic monopoles produced via the Schwinger mechanism

Electrically charged particles can be created by the decay of strong enough electric fields, a phenomenon known as the Schwinger mechanism¹. By electromagnetic duality, a sufficiently strong magnetic field would similarly produce magnetic monopoles, if they exist². Magnetic monopoles are hypothetical fundamental particles that are predicted by several theories beyond the standard model^3-7 but have never been experimentally detected. Searching for the existence of magnetic monopoles via the Schwinger mechanism has not yet been attempted, but it is advantageous, owing to the possibility of calculating its rate through semi-classical techniques without perturbation theory, as well as that the production of the magnetic monopoles should be enhanced by their finite size^8,9 and strong coupling to photons^2,10. Here we present a search for magnetic monopole production by the Schwinger mechanism in Pb-Pb heavy ion collisions at the Large Hadron Collider, producing the strongest known magnetic fields in the current Universe¹¹. It was conducted by the MoEDAL experiment, whose trapping detectors were exposed to 0.235 per nanobarn, or approximately 1.8 × 10⁹, of Pb-Pb collisions with 5.02-teraelectronvolt center-of-mass energy per collision in November 2018. A superconducting quantum interference device (SQUID) magnetometer scanned the trapping detectors of MoEDAL for the presence of magnetic charge, which would induce a persistent current in the SQUID. Magnetic monopoles with integer Dirac charges of 1, 2 and 3 and masses up to 75 gigaelectronvolts per speed of light squared were excluded by the analysis at the 95% confidence level. This provides a lower mass limit for finite-size magnetic monopoles from a collider search and greatly extends previous mass bounds.

Impact of Social Frailty on Relocation of Older Adults

BACKGROUND

The relationship between frailty and variables such as housing are the least included in models of frailty and research on frailty or social frailty and relocation is negligible. The decision to relocate is complex and demanding for older adults with a loss of independence but little is known about what makes older adults relocate to congregated housing designated for older adults, let alone in combination with social frailty, and how they navigate this transition.

OBJECTIVES

This mixed method descriptive study aims to understand the influence of social frailty for a population of French-speaking semi-independent older adults relocating to a housing continuum community.

DESIGN

Semi-structured individual interviews including sociodemographic data and the PRISMA-7 Frailty Scale were conducted with recently relocated older adults.

SETTING

A newly opened French-speaking housing continuum community in Eastern Canada that offers luxury apartments for independent older adults, two assisted living facilities for semi-independent older adults along with a long-term care facility.

PARTICIPANTS

Twenty-nine older adults with a mean age of 85 years, mostly female, married or widowed and highly educated.

MEASUREMENTS

Content analysis of the transcribed recorded interviews and descriptive statistical analyses to examine relationships between the frailty PRISMA-7 scale, answers to additional questions and the sociodemographic data.

RESULTS

There was not a significant difference in the scores for socialization before and after relocation nor between prior help and current help; however, there was a significant negative correlation between help and socialization before and after relocation. Three main themes included: imposed influences, push and pull factors and post relocation.

CONCLUSIONS

The results indicate that several social factors contributed to relocation and that participants were experiencing social frailty. Participants were at the crossover point of being vulnerable to experiencing additional deficits which would potentially have led to higher frailty had they not relocated.

Feasibility of perioperative volatile organic compound breath testing for prediction of paralytic ileus following laparoscopic colorectal resection

BACKGROUND

Despite implementation of enhanced recovery after surgery (ERAS) and laparoscopic techniques, postoperative ileus (POI) remains frequent after colorectal surgery, impacting the patient, their recovery and health-care resources. Presently there are no tests that reliably predict or enable early POI diagnosis. Volatile organic compounds (VC) are products of human and microbiota cellular metabolism and we hypothesised that a detectable alteration occurs in POI.

METHOD

This was a prospective observational study of patients undergoing laparoscopic colorectal resection within an established ERAS programme. Standardized end-expiratory breath sampling was performed on the morning of surgery and on the first three postoperative mornings. The concentrations of VCs commonly found in intestinal gas were analysed using selected ion flow tube mass spectrometry and GastroCH₄ ECK®. Feasibility data, bowel preparation, postoperative oral intake, POI and 30-day morbidity were recorded.

RESULTS

Of the 75 potentially eligible patients, 58 (77%) agreed to participate. Per-protocol breath sampling was successfully completed in 94%. There were no analytical failures. Baseline and postoperative concentrations of VCs were broadly comparable and were not altered by bowel preparation or postoperative oral intake. POI developed in 14 (29%) patients. Preoperative ammonia concentration was higher in patients who developed POI [830 parts per billion (ppb) vs 510 ppb, P = 0.027]. There was an increase in the concentration of acetic acid detected on day 2 in patients who developed POI (99 ppb vs 171 ppb, P = 0.021).

CONCLUSION

Repeated VC breath sampling and analysis is feasible in the perioperative setting. An elevated ammonia concentration on the morning of surgery may be a potential predictor of POI.

The Brookhaven National Laboratory electron beam ion source for RHIC

As part of a new heavy ion preinjector that will supply beams for the Relativistic Heavy Ion Collider and the National Aeronautics and Space Administration Space Radiation Laboratory, construction of a new electron beam ion source (EBIS) is now being completed. This source, based on the successful prototype Brookhaven National Laboratory Test EBIS, is designed to produce milliampere level currents of all ion species, with q/m=(1/6)-(1/2). Among the major components of this source are a 5 T, 2-m-long, 204 mm diameter warm bore superconducting solenoid, an electron gun designed to operate at a nominal current of 10 A, and an electron collector designed to dissipate approximately 300 kW of peak power. Careful attention has been paid to the design of the vacuum system, since a pressure of 10(-10) Torr is required in the trap region. The source includes several differential pumping stages, the trap can be baked to 400 C, and there are non-evaporable getter strips in the trap region. Power supplies include a 15 A, 15 kV electron collector power supply, and fast switchable power supplies for most of the 16 electrodes used for varying the trap potential distribution for ion injection, confinement, and extraction. The EBIS source and all EBIS power supplies sit on an isolated platform, which is pulsed up to a maximum of 100 kV during ion extraction. The EBIS is now fully assembled, and operation will be beginning following final vacuum and power supply tests. Details of the EBIS components are presented.