Self-adjoint Time Operator is the Rule for Discrete Semibounded Hamiltonians

We prove explicitly that to every discrete, semibounded Hamiltonian with constant degeneracy and with finite sum of the squares of the reciprocal of its eigenvalues and whose eigenvectors span the entire Hilbert space there exists a characteristic self-adjoint time operator which is canonically conjugate to the Hamiltonian in a dense subspace of the Hilbert space. Moreover, we show that each characteristic time operator generates an uncountable class of self- adjoint operators canonically conjugate with the same Hamiltonian in the same dense subspace.Comment: accepted for publication in the Proceedings of the Royal Society of London

Molecular mechanisms of retroviral integration site selection

Retroviral replication proceeds through an obligate integrated DNA provirus, making retroviral vectors attractive vehicles for human gene-therapy. Though most of the host cell genome is available for integration, the process of integration site selection is not random. Retroviruses differ in their choice of chromatin-associated features and also prefer particular nucleotide sequences at the point of insertion. Lentiviruses including HIV-1 preferentially integrate within the bodies of active genes, whereas the prototypical gammaretrovirus Moloney murine leukemia virus (MoMLV) favors strong enhancers and active gene promoter regions. Integration is catalyzed by the viral integrase protein, and recent research has demonstrated that HIV-1 and MoMLV targeting preferences are in large part guided by integrase-interacting host factors (LEDGF/p75 for HIV-1 and BET proteins for MoMLV) that tether viral intasomes to chromatin. In each case, the selectivity of epigenetic marks on histones recognized by the protein tether helps to determine the integration distribution. In contrast, nucleotide preferences at integration sites seem to be governed by the ability for the integrase protein to locally bend the DNA duplex for pairwise insertion of the viral DNA ends. We discuss approaches to alter integration site selection that could potentially improve the safety of retroviral vectors in the clinic

The p85 regulatory subunit of phosphoinositide 3-kinase down-regulates IRS-1 signaling via the formation of a sequestration complex

Phosphoinositide (PI) 3-kinase is required for most insulin and insulin-like growth factor (IGF) 1–dependent cellular responses. The p85 regulatory subunit of PI 3-kinase is required to mediate the insulin-dependent recruitment of PI 3-kinase to the plasma membrane, yet mice with reduced p85 expression have increased insulin sensitivity. To further understand the role of p85, we examined IGF-1–dependent translocation of p85α by using a green fluorescence protein (GFP)–tagged p85α (EGFP–p85α). In response to IGF-1, but not to PDGF signaling, EGFP–p85α translocates to discrete foci in the cell. These foci contain the insulin receptor substrate (IRS) 1 adaptor molecule, and their formation requires the binding of p85 to IRS-1. Surprisingly, monomeric p85 is preferentially localized to these foci compared with the p85–p110 dimer, and these foci are not sites of phosphatidylinositol-3,4,5-trisphosphate production. Ultrastructural analysis reveals that p85–IRS-1 foci are cytosolic protein complexes devoid of membrane. These results suggest a mechanism of signal down-regulation of IRS-1 that is mediated by monomeric p85 through the formation of a sequestration complex between p85 and IRS-1

First Observations of Long-Lived Meteor Trains with Resonance Lidar and Other Optical Instruments

In November 1998 the earth passed through a maximum in the cometary material responsible for the yearly Leonids meteor shower. The meteor storm event produced numerous examples of long-lived chemiluminescent trails--visible to the naked eye over New Mexico, where a major observation campaign was centered. One trail was detected for over an hour with a CCD camera employing a narrow sodium filter, and many others were observed for over ten minutes each. For the first time, sodium densities in such trails were measured while also being imaged in sodium light. We have verified one source of long-lived light emissions--a sodium-catalyzed reaction involving ozone--but it is far too weak to explain the visibility of such trails. In addition, we present a new explanation for the cylindrical shell appearance long reported for chemiluminescent trails and show that ozone depletion by chemical processes is a possible explanation for this phenomenon

The Role of Demography in the Transition to Sustainable Societies

Currently, although the global population has surpassed 7.5 billion and continues to increase in about 80 million each year, attention to demography is almost absent in most of the studies and publications related to the current situation of planetary emergency and the necessary transition to sustainable societies. For this reason, our first aim in this paper has been to discuss if this current lack of attention to demography is justified or not. With this purpose, we begin considering the scientific meaning of Sustainability, in order to overlay distorted and impoverish views of this concept that may hinder our study. Then, we analyse the reasons given by experts for and against the incidence of demographic growth in the current unsustainable situation of planetary emergency. Finally, we present proposals to face the ensemble of interconnected socio-environmental problems (including demographic evolution), to make possible an appropriate transition to sustainable societies. Aunque la población mundial ha sobrepasado los 7500 millones y continúa aumentando anualmente en alrededor de 80 millones, la atención a la demografía está hoy prácticamente ausente en la mayoría de los estudios y publicaciones acerca de la actual situación de emergencia planetaria y la necesidad de una transición a sociedades sostenibles. Con el propósito de analizar si esta falta de atención a la demografía está o no justificada, en esta contribución comenzamos discutiendo el significado científico de Sostenibilidad socioambiental, para evitar concepciones distorsionadas y empobrecidas de este concepto que pueden dificultar dicho análisis. A continuación estudiaremos las razones dadas por distintos expertos a favor y en contra de la incidencia del crecimiento demográfico en la insostenible situación actual de emergencia planetaria. Finalmente presentamos propuestas para hacer frente al conjunto de problemas estrechamente interconectados - incluido el problema demográfico - que caracterizan dicha situación, para hacer así posible una adecuada transición a sociedades sostenibles

Adult cardiac surgery during the COVID-19 Pandemic: A Tiered Patient Triage Guidance Statement

In the setting of the current novel coronavirus pandemic, this document has been generated to provide guiding statements for the adult cardiac surgeon to consider in a rapidly evolving national landscape. Acknowledging the risk for a potentially prolonged need for cardiac surgery procedure deferral, the authors have created this proposed template for physicians and interdisciplinary teams to consider in protecting their patients, institution and their highly specialized cardiac surgery team. In addition, recommendations on the transition from traditional in-person patient assessments and outpatient follow-up are provided. Lastly, we advocate that the cardiac surgeon must continue to serve as leaders, experts, and relevant members of our medical community, shifting our role as necessary in this time of need

Pion-Lambda-Sigma Coupling Extracted from Hyperonic Atoms

The latest measurements of the atomic level width in Sigma-hyperonic Pb atom offer the most accurate datum in the region of low-energy Sigma-hyperon physics. Atomic widths are due to the conversion of Sigma-nucleon into Lambda-nucleon. In high angular momentum states this conversion is dominated by the one-pion exchange. A joint analysis of the data of the scattering of negative-Sigma on proton converting into a Lambda and a neutron and of the atomic widths allows to extract a pseudovector pion-hyperon-Sigma coupling constant of 0.048 with a statistical error of +-0.005 and a systematic one of +-0.004. This corresponds to a pseudoscalar coupling constant of 13.3 with a statistical uncertainty of 1.4 and a systematic one of 1.1.Comment: 12 pages, 1 figure, Use of Revtex.st

Focused cardiac ultrasound screening for rheumatic heart disease by briefl y trained health workers: a study of diagnostic accuracy

Background Echocardiographic screening for rheumatic heart disease (RHD) can identify individuals with subclinical disease who could benefi t from antibiotic prophylaxis. However, most settings have inadequate resources to implement conventional echocardiography and require a feasible, accurate screening method. We aimed to investigate the accuracy of screening by non-expert operators using focused cardiac ultrasound (FoCUS). Methods In this prospective study of diagnostic accuracy, we recruited schoolchildren aged 5 to 15 years in Fiji to undergo two blinded tests. The index test was a FoCUS assessment of mitral and aortic regurgitation, performed by nurses after an 8-week training programme. The reference standard was the diagnosis of RHD by a paediatric cardiologist, based on a standard echocardiogram performed by a skilled echocardiographer. The primary outcome was the accuracy of the index test with use of the most sensitive criteria (any regurgitation). Findings We included 2004 children in the study. The index tests were done between September, 2012, and September, 2013, by seven nurses in eight schools in Fiji. The diagnostic accuracy of the screening test (area under receiver operator characteristic curve) was 0·89 (95% CI 0·83–0·94). When the primary cut-off point (any regurgitation) was used for analysis, sensitivity was 84·2% (72·1–92·5) and specifi city was 85·6% (83·9–87·1). The sensitivity of individual nurses ranged from 66·7% to 100% and specifi city 74·0% to 93·7%. Interpretation Screening by briefl y trained nurses using FoCUS was accurate for the diagnosis of RHD. Refi nements to training and screening test methods should be studied in a range of settings, and in parallel with investigations of the long-term clinical and cost-eff ectiveness of screening for RHD

Ramping up Delivery of Cardiac Surgery During the COVID-19 Pandemic: A Guidance Statement from The Society of Thoracic Surgeons COVID-19 Task Force

The COVID-19 pandemic has had a profound global impact. Its rapid transmissibility has transformed healthcare delivery and forced countries to adopt strict measures to contain its spread. The vast majority of U.S. cardiac surgical programs have deferred all but truly emergent/urgent operative procedures in an effort to reduce the burden on the healthcare system and to mobilize resources to combat the pandemic surge. While the number of COVID-19 cases continues to increase worldwide, the incidence of new cases has begun to decline in many North American cities. This flattening of the curve has prompted interest in re-opening the economy, relaxing public health restrictions, and resuming non-urgent health care delivery