The Cosmological Constant

This is a review of the physics and cosmology of the cosmological constant. Focusing on recent developments, I present a pedagogical overview of cosmology in the presence of a cosmological constant, observational constraints on its magnitude, and the physics of a small (and potentially nonzero) vacuum energy.Comment: 50 pages. Submitted to Living Reviews in Relativity (http://www.livingreviews.org/), December 199

ACL injuries identifiable for pre-participation imagiological analysis: Risk factors

Identification of pre-participation risk factors for noncontact anterior cruciate ligament (ACL) injuries has been attracting a great deal of interest in the sports medicine and traumatology communities. Appropriate methods that enable predicting which patients could benefit from pre- ventive strategies are most welcome. This would enable athlete-specific training and conditioning or tailored equipment in order to develop appropriate strategies to reduce incidence of injury. In order to accomplish these goals, the ideal system should be able to assess both anatomic and functional features. Complementarily, the screening method must be cost-effective and suited for widespread application. Anatomic study protocol requiring only standard X rays could answer some of such demands. Dynamic MRI/CT evaluation and electronically assisted pivot-shift evaluation can be powerful tools providing complementary information. These upcoming insights, when validated and properly combined, envision changing pre-participation knee examination in the near future. Herein different methods (validated or under research) aiming to improve the capacity to identify persons/athletes with higher risk for ACL injury are overviewed.

Evolutionary and pulsational properties of white dwarf stars

Abridged. White dwarf stars are the final evolutionary stage of the vast majority of stars, including our Sun. The study of white dwarfs has potential applications to different fields of astrophysics. In particular, they can be used as independent reliable cosmic clocks, and can also provide valuable information about the fundamental parameters of a wide variety of stellar populations, like our Galaxy and open and globular clusters. In addition, the high densities and temperatures characterizing white dwarfs allow to use these stars as cosmic laboratories for studying physical processes under extreme conditions that cannot be achieved in terrestrial laboratories. They can be used to constrain fundamental properties of elementary particles such as axions and neutrinos, and to study problems related to the variation of fundamental constants. In this work, we review the essentials of the physics of white dwarf stars. Special emphasis is placed on the physical processes that lead to the formation of white dwarfs as well as on the different energy sources and processes responsible for chemical abundance changes that occur along their evolution. Moreover, in the course of their lives, white dwarfs cross different pulsational instability strips. The existence of these instability strips provides astronomers with an unique opportunity to peer into their internal structure that would otherwise remain hidden from observers. We will show that this allows to measure with unprecedented precision the stellar masses and to infer their envelope thicknesses, to probe the core chemical stratification, and to detect rotation rates and magnetic fields. Consequently, in this work, we also review the pulsational properties of white dwarfs and the most recent applications of white dwarf asteroseismology.Comment: 85 pages, 28 figures. To be published in The Astronomy and Astrophysics Revie

Microvertebrates preserved in mammal burrows from the Holocene of the Argentine Pampas: a taphonomic and paleoecological approach

Microvertebrates are a major component of many assemblages recovered from the Quaternary of the Argentine Pampas. The main goal of this paper is to analyse the taphonomic history of a Holocene microfossil bonebed, recovered from the infilling of a burrow. Evidences suggest the plains vizcacha Lagostomus maximus as the putative producer of the burrow. The assemblage includes individuals belonging to different taxa of mammals (marsupials and rodents) and reptiles (snakes). Taphonomic features suggest that the accumulation inside the burrow was related to flooding processes in the plain. The burrow was a natural trap that favoured the accumulation and preservation of remains corresponding to individuals from different sources. According to the taphonomic evidence, some individuals (Lagostomus maximus, Lestodelphys halli and Serpentes indet.) died inside the burrow, whereas others (Microcavia australis, Reithrodon auritus and Ctenomys sp.) died outside the burrow, and after a time of being exposed on the surface their remains were transported by surface run-offs into the burrow. The record of Lestodelphys halli and Serpentes indet. in the burrow produced by Lagostomus maximus could be related to a circumstantial use. Mammal burrows are a significant taphonomic mode for the late Cenozoic of the Argentine Pampas

Long-term passive acoustic recordings track the changing distribution of North Atlantic right whales (Eubalaena glacialis) from 2004 to 2014

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Scientific Reports 7 (2017): 13460, doi:10.1038/s41598-017-13359-3.Given new distribution patterns of the endangered North Atlantic right whale (NARW; Eubalaena glacialis) population in recent years, an improved understanding of spatio-temporal movements are imperative for the conservation of this species. While so far visual data have provided most information on NARW movements, passive acoustic monitoring (PAM) was used in this study in order to better capture year-round NARW presence. This project used PAM data from 2004 to 2014 collected by 19 organizations throughout the western North Atlantic Ocean. Overall, data from 324 recorders (35,600 days) were processed and analyzed using a classification and detection system. Results highlight almost year-round habitat use of the western North Atlantic Ocean, with a decrease in detections in waters off Cape Hatteras, North Carolina in summer and fall. Data collected post 2010 showed an increased NARW presence in the mid-Atlantic region and a simultaneous decrease in the northern Gulf of Maine. In addition, NARWs were widely distributed across most regions throughout winter months. This study demonstrates that a large-scale analysis of PAM data provides significant value to understanding and tracking shifts in large whale movements over long time scales.This research was funded and supported by many organizations, specified by projects as follows: Data recordings from region 1 were provided by K. Stafford and this research effort was funded by the National Science Foundation #NSF-ARC 0532611. Region 2 data were provided by D. K. Mellinger and S. Nieukirk, funded by National Oceanic and Atmospheric Agency (NOAA) and the Office of Naval Research (ONR) #N00014–03–1–0099, NOAA #NA06OAR4600100, US Navy #N00244-08-1-0029, N00244-09-1-0079, and N00244-10-1-0047

Real patient learning integrated in a preclinical block musculoskeletal disorders. Does it make a difference?

Although musculoskeletal disorders are the most common reason for general practitioner visits, training did not keep pace. Implementation of learning from patients with rheumatologic disorders linked together with the teaching of theoretical knowledge in the preclinical medical education might be an important step forward in the improvement of quality of care for these patients. The Leiden Medical School curriculum has implemented two non-obligatory real patient learning (RPL) practicals integrated within the preclinical block musculoskeletal disorders. This study investigates the educational effectiveness of the practicals, the expectations students have of RPL, and students’ satisfaction. Participants’ grades on the end-of-block test served as the test results of the educational effectiveness of the practicals and were compared with those of the non-participants. Qualitative data was collected by means of questionnaires generated by focus groups. The participants in practicals scored significantly higher at the end-of-block test. The expected effects of the contact with real patients concerned positive effects on cognition and skills. ‘Contextualizing of the theory’, ‘better memorizing of clinical pictures’, and ‘understanding of the impact of the disease’ were the most frequently mentioned effects of the practicals. Overall, the participants were (very) enthusiastic about this educational format. The RPL practicals integrated within a preclinical block musculoskeletal disorders are a valuable addition to the Leiden medical curriculum. This relatively limited intervention exhibits a strong effect on students’ performance in tests. Future research should be directed towards the long-term effects of this intervention

Assessing the magnitude and trends in hospital acquired infections in Canadian hospitals through sequential point prevalence surveys

Abstract Background Healthcare acquired infections (HAI) are an important public health problem in developed countries, but comprehensive data on trends over time are lacking. Prevalence surveys have been used as a surrogate for incidence studies and can be readily repeated. Methods The Canadian Nosocomial Infection Surveillance Program conducted prevalence surveys in 2002 and 2009 in a large network of major Canadian acute care hospitals. NHSN definitions of HAI were used. Use of isolation precautions on the survey day was documented. Results In 2009, 9,953 acute care inpatients were surveyed; 1,234 infections (124/1000) were found, compared to 111/1000 in 2002, (p < 0.0001). There was increased prevalence of urinary tract infection (UTI) and Clostridium difficile, offset by decreases in pneumonia and bloodstream infection. Use of isolation precautions increased from 77 to 148 per 1000 patients (p < 0.0001), attributable to increased use of contact precautions in patients infected or colonized with antimicrobial resistant organisms. Conclusion Between 2002 and 2009 HAI prevalence increased by 11.7 % in a network of major Canadian hospitals due to increases in Clostridium difficile and urinary tract infection. The use of isolation precautions increased by 92.2 % attributable to increased contact isolation. National prevalence surveys are useful tools to assess evolving trends in HAI

The role of peer meetings for professional development in health science education: a qualitative analysis of reflective essays

Introduction The development of professional behaviour is an important objective for students in Health Sciences, with reflective skills being a basic condition for this development. Literature describes a variety of methods giving students opportunities and encouragement for reflection. Although the literature states that learning and working together in peer meetings fosters reflection, these findings are based on experienced professionals. We do not know whether participation in peer meetings also makes a positive contribution to the learning experiences of undergraduate students in terms of reflection. Aim The aim of this study is to gain an understanding of the role of peer meetings in students’ learning experiences regarding reflection. Method A phenomenographic qualitative study was undertaken. Students’ learning experiences in peer meetings were analyzed by investigating the learning reports in students’ portfolios. Data were coded using open coding. Results The results indicate that peer meetings created an interactive learning environment in which students learned about themselves, their skills and their abilities as novice professionals. Students also mentioned conditions for a well-functioning group. Conclusion The findings indicate that peer meetings foster the development of reflection skills as part of professional behaviour

Persistent Expression of Hepatitis C Virus Non-Structural Proteins Leads to Increased Autophagy and Mitochondrial Injury in Human Hepatoma Cells

HCV infection is a major cause of chronic liver disease and liver cancer in the United States. To address the pathogenesis caused by HCV infection, recent studies have focused on the direct cytopathic effects of individual HCV proteins, with the objective of identifying their specific roles in the overall pathogenesis. However, this approach precludes examination of the possible interactions between different HCV proteins and organelles. To obtain a better understanding of the various cytopathic effects of and cellular responses to HCV proteins, we used human hepatoma cells constitutively replicating HCV RNA encoding either the full-length polyprotein or the non-structural proteins, or cells constitutively expressing the structural protein core, to model the state of persistent HCV infection and examined the combination of various HCV proteins in cellular pathogenesis. Increased reactive oxygen species (ROS) generation in the mitochondria, mitochondrial injury and degeneration, and increased lipid accumulation were common among all HCV protein-expressing cells regardless of whether they expressed the structural or non-structural proteins. Expression of the non-structural proteins also led to increased oxidative stress in the cytosol, membrane blebbing in the endoplasmic reticulum, and accumulation of autophagocytic vacuoles. Alterations of cellular redox state, on the other hand, significantly changed the level of autophagy, suggesting a direct link between oxidative stress and HCV-mediated activation of autophagy. With the wide-spread cytopathic effects, cells with the full-length HCV polyprotein showed a modest antioxidant response and exhibited a significant increase in population doubling time and a concomitant decrease in cyclin D1. In contrast, cells expressing the non-structural proteins were able to launch a vigorous antioxidant response with up-regulation of antioxidant enzymes. The population doubling time and cyclin D1 level were also comparable to that of control cells. Finally, the cytopathic effects of core protein appeared to focus on the mitochondria without remarkable disturbances in the cytosol

The impact of trained patient educators on musculoskeletal clinical skills attainment in pre-clerkship medical students

<p>Abstract</p> <p>Background</p> <p>Despite the high burden of musculoskeletal (MSK) diseases, few generalists are comfortable teaching MSK physical examination (PE) skills. Patient Partners^®in Arthritis (PP^®IA) is a standardized patient educator program that could potentially supplement current MSK PE teaching. This study aims to determine if differences exist in MSK PE skills between non-MSK specialist physician and PP^®IA taught students.</p> <p>Methods</p> <p>Pre-clerkship medical students attended 2-hour small group MSK PE teaching by either non-MSK specialist physician tutors or by PP^®IA. All students underwent an MSK OSCE and completed retrospective pre-post questionnaires regarding comfort with MSK PE and interest in MSK.</p> <p>Results</p> <p>83 students completed the OSCE (42 PP^®IA, 41 physician taught) and 82 completed the questionnaire (42 PP^®IA, 40 physician taught). There were no significant differences between groups in OSCE scores. For all questionnaire items, post-session ratings were significantly higher than pre-session ratings for both groups. In exploratory analysis PP^®IA students showed significantly greater improvement in 12 of 22 questions including three of five patient-centred learning questions.</p> <p>Conclusions</p> <p>PP^®IA MSK PE teaching is as good as non-MSK specialist physician tutor teaching when measured by a five station OSCE and provide an excellent complementary resource to address current deficits in MSK PE teaching.</p