Dynamics of Tachyonic Dark Matter

Usually considered highly speculative, tachyons can be treated via straightforward Einsteinian dynamics. Kinetic theory and thermodynamics for a gas of ``dark'' tachyons are readily constructed. Such a gas exhibits density and pressure which, for the dominant constituent of a suitable Friedmann-Robertson-Walker spacetime, can drive cosmic evolution with features both similar to and distinct from those of a standard dark-energy/dark-matter model. Hence, tachyons might bear further consideration as a cosmic dark-matter candidate.Comment: 16 pages, 1 figur

‘Effectiveness of Continuing Professional Development’ project: a summary of findings

This article reports on a study examining continuing professional development (CPD) for consultant doctors. The aim of the study was to identify what promotes or inhibits the effectiveness of CPD and met the following objectives: comparing and contrasting the experiences of CPD across the range of specialties; identifying and describing the range of different models of CPD employed across the different specialties and clinical contexts; considering the educational potential of reflective practice in CPD and its impact on professional practice and exploring how different professionals judge the effectiveness of current CPD practices. Using a mixture of qualitative (interviews, letters, observation) and quantitative (online questionnaire) methods, the views of CPD providers and users were surveyed. Findings suggested that the effectiveness of CPD, as inferred from the comments made by interviewees and questionnaire respondents, relates to the impact on knowledge, skills, values, attitudes, behaviours and changes in practice in the work place. The quality of CPD was seen as inextricably linked to any improvements in the quality of the professional practices required for service delivery. There was widespread consensus as to the value of learning in professional settings. There was recognition that there needs to be a move away from tick boxes to the in-depth identification of learning needs and how these can be met both within and external to the work place, with learning being adequately enabled and assessed in all locations. In conclusion, it can be said that CPD is valued and is seen as effective when it addresses the needs of individual clinicians, the populations they serve and the organisations within which they work. However, the challenge for CPD may lie in the dynamic interaction between educational opportunities and service delivery requirements, as there may be occasions where they vie with each other for resources

Assessing the Uncertainties of Simulation Approaches for Solar Thermal Systems Coupled to Industrial Processes

Industrial energy accounts for a large percentage of global consumption and, thus, it is a target for decarbonization by renewable and in particular solar energy adoption. Low uncertainty simulation tools can reduce the financial risk of solar projects, fostering the transition to a sustainable energy system. Several simulation tools are readily available to developers; differences exist in the format of input data and complexity of physical and numerical models. These tools can provide a variety of results from technical to financial and sensitivity analysis, often producing significant differences in yield assessment and uncertainty levels. IEA SHC Task 64/SolarPACES Task IV— Subtask C aims to address the lack of standard simulation tools for Solar Heating of Industrial Processes (SHIP) plants. This article describes the collaborative work developed by the researchers participating in the task. The identification and classification of several currently available simulation tools are performed on the basis of their capabilities and simulation approaches. A case study of solar heat supply to a copper mining operation is defined, allowing a comparison of the results produced by equivalent simulation tools. The proposed methodology identifies the main sources of differences among the simulation tools, the assessment of the deviation considering a series of statistical metrics for different time scales, and identifies their limitations and bias. The effects of physical characteristics of SHIP plants and different simulation approaches are discussed and quantified. The obtained results allow us to develop a basic guideline for a standardized yield assessment procedure with known uncertainties. Creating this common framework could partially reduce the risk perceived by the finance industry regarding SHIP systems.ANID/REDES/190164, ANID/FONDAP 15110019 “Centro de Investigación en Energía Solar”— SERC-Chile y CORFO/13CEI2-21803.ANID PFCHA/DOCTORADO BECAS CHILE/2017 ANID PFCHA/Doctorado Nacional 2021-2121005

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

The Expression Of Prion Protein By Endothelial Cells: A Source Of The Plasma Form Of Prion Protein?

Summary. The neuronal prion protein (PrPC) is also expressed within peripheral tissues including human blood. The majority of blood PrPC is found within the plasma fraction. We hypothesized that the vascular endothelium could be a source of this PrPC. Reverse transcription polymerase chain reaction demonstrated that both human umbilical vein endothelial cells (HUVEC) and human microvascular endothelial cells (HMEC-1) expressed PrPC mRNA. Flow cytometry confirmed PrPC expression on HMEC-1s and HUVECs (120 900 ± 15 058 and 58 327 ± 4577 molecules PrPC/cell respectively), with no upregulation following cellular activation. Confocal immunofluorescence microscopy confirmed that HMEC-1s and HUVECs were positive for PrPC on the plasma membrane. Time-resolved dissociation-enhanced fluoroimmunoassay (DELFIA®) analysis of cell culture medium demonstrated a slow constitutive release of soluble PrPC not associated with activation. In contrast to von Willebrand factor antigen, PrPC plasma levels in vivo decrease following desmopressin therapy in patients with von Willebrand disease. Measurement of PrPC plasma levels in patients with varying blood counts demonstrated no association between cell count and PrPC concentration. However, there was a higher level of PrPC in plasma from patients with end-stage renal failure. In conclusion, endothelial cells of both macrovascular and microvascular origin expressed high levels of PrPC which can be constitutively released into the cell culture medium

Strengthening Tuberculosis Services for Children and Adolescents in Low Endemic Settings

In low tuberculosis-burden countries, children and adolescents with the highest incidence of tuberculosis (TB) infection or disease are usually those who have immigrated from high-burden countries. It is, therefore, essential that low-burden countries provide healthcare services to immigrant and refugee families, to assure that their children can receive proper testing, evaluation, and treatment for TB. Active case-finding through contact tracing is a critical element of TB prevention in children and in finding TB disease at an early, easily treated stage. Passive case-finding by evaluating an ill child is often delayed, as other, more common infections and conditions are suspected initially. While high-quality laboratory services to detect Mycobacterium tuberculosis are generally available, they are often underutilized in the diagnosis of childhood TB, further delaying diagnosis in some cases. Performing research on TB disease is difficult because of the low number of cases that are spread over many locales, but critical research on the evaluation and treatment of TB infection has been an important legacy of low-burden countries. The continued education of medical providers and the involvement of educational, professional, and non-governmental organizations is a key element of maintaining awareness of the presence of TB. This article provides the perspective from North America and Western Europe but is relevant to many low-endemic settings. TB in children and adolescents will persist in low-burden countries as long as it persists throughout the rest of the world, and these wealthy countries must increase their financial commitment to end TB everywhere