de Sitter symmetry of Neveu-Schwarz spinors

We study the relations between Dirac fields living on the 2-dimensional Lorentzian cylinder and the ones living on the double-covering of the 2-dimensional de Sitter manifold, here identified as a certain coset space of the group $SL(2,R)$. We show that there is an extended notion of de Sitter covariance only for Dirac fields having the Neveu-Schwarz anti-periodicity and construct the relevant cocycle. Finally, we show that the de Sitter symmetry is naturally inherited by the Neveu-Schwarz massless Dirac field on the cylinder.Comment: 24 page

Deuteronomy and Numbers

Four light isotopes - D, ^3He, ^4He and ^7Li - were produced by nuclear reactions a few seconds after the big bang. New measurements of ^3He in the ISM by Gloeckler and Geiss and of deuterium in high redshift hydrogen clouds by Tytler and his collaborators provide further confirmation of big-bang nucleosynthesis and new insight about the density of ordinary matter (baryons).Comment: 6 pages LaTeX with 1 eps Figur

A Universal Model of Global Civil Unrest

Civil unrest is a powerful form of collective human dynamics, which has led to major transitions of societies in modern history. The study of collective human dynamics, including collective aggression, has been the focus of much discussion in the context of modeling and identification of universal patterns of behavior. In contrast, the possibility that civil unrest activities, across countries and over long time periods, are governed by universal mechanisms has not been explored. Here, we analyze records of civil unrest of 170 countries during the period 1919-2008. We demonstrate that the distributions of the number of unrest events per year are robustly reproduced by a nonlinear, spatially extended dynamical model, which reflects the spread of civil disorder between geographic regions connected through social and communication networks. The results also expose the similarity between global social instability and the dynamics of natural hazards and epidemics.Comment: 8 pages, 3 figure

A High Deuterium Abundance at z=0.7

Of the light elements, the primordial abundance of deuterium, (D/H)_p, provides the most sensitive diagnostic for the cosmological mass density parameter Omega_B. Recent high redshift (D/H) measurements are highly discrepant, although this may reflect observational uncertainties. The larger (D/H) values, which imply a low Omega_B and require the Universe to be dominated by non-baryonic matter (dynamical studies indicate a higher total density parameter), cause problems for galactic chemical evolution models since they have difficulty in reproducing the large decline down to the lower present-day (D/H). Conversely, low (D/H) values imply an Omega_B greater than derived from ^7Li and ^4He abundance measurements, and may require a deuterium abundance evolution that is too low to easily explain. Here we report the first measurement at intermediate redshift, where the observational difficulties are smaller, of a gas cloud with ideal characteristics for this experiment. Our analysis of the z = 0.7010 absorber toward 1718+4807 indicates (D/H) = 2.0 +/- 0.5 x 10^{-4} which is in the high range. This and other independent observations suggests there may be a cosmological inhomogeneity in (D/H)_p of at least a factor of ten.Comment: 6 pages, 1 figur

Hipertensión arterial inducida por el tratamiento con antiangiogénicos en el paciente oncológico

Introduction: high blood pressure is a multifactorial disease; there is a wide range of stimuli that can trigger it, including drugs.Objective: to describe the pathophysiological mechanisms involved in the development of hypertension induced by treatment with antiangiogenic drugs in oncological patients.Methods: a search for information was carried out in the PubMed/MEDLINE, SciELO and Scopus databases. Twenty-four bibliographic references were chosen.Development: the mechanisms of blood pressure elevation in patients treated with antiangiogenic agents are multifactorial. The mechanisms involved are not seen in isolation, but some are cause and/or effect of others. This interrelationship is shown during inhibition of vascular endothelial growth factor A, which is associated with a decrease in serum levels of nitric oxide metabolites, which triggers sodium retention and increased local and systemic blood pressure, showing changes in renal dynamics. Monitoring is necessary to allow early diagnosis and adequate treatment. This suggests that the use of appropriate antihypertensive drugs may be necessary for maintenance therapy to avoid dose interruption/discontinuation. Conclusions: there are several pathophysiological mechanisms related to the development of hypertension during treatment with antiangiogenic drugs such as induction of vascular endothelial growth factor A, variations in nitric oxide production, increased expression of pre-hypertensive agents such as endothelin-1, microvascular rare- fraction, activation of the renin-angiotensin system and oxidative stress.Introducción: la hipertensión arterial una enfermedad multifactorial; existe una alta gama de estímulos que pueden desencadenarla, entre ellos, los medicamentos.Objetivo: describir los mecanismos fisiopatológicos que intervienen en el desarrollo de hipertensión arterial inducida por el tratamiento con antiangiogénicos en pacientes oncológicos.Métodos: se realizó una búsqueda de información en las bases de datos PubMed/MEDLINE, SciELO y Scopus. Se seleccionaron 24 referencias bibliográficas.Desarrollo: los mecanismos de elevación de la presión arterial en pacientes tratados con antiangiogénicos son multifactoriales. Los mecanismos implicados no se ven de forma aislada, sino que unos son causa y/o efecto de otros. Esta interrelación se muestra durante la inhibición del factor A del crecimiento endotelial vascular, que se asocia con una disminución de los niveles séricos de los metabolitos del óxido nítrico, el cual desencadena la retención de sodio y aumento de la presión arterial local y sistémica, mostrando cambios en la dinámica renal. Es necesaria una monitorización que permita un diagnóstico temprano y tratamiento adecuado. Esto sugiere que el uso de medicamentos antihipertensivos apropiados puede ser necesario para la terapia de mantenimiento, a fin de evitar la interrupción/discontinuación de la dosis.Conclusiones: existen varios mecanismos fisiopatológicos relacionados al desarrollo de hipertensión arterial durante el tratamiento con antiangiogénicos como la inducción del factor A de crecimiento endotelial vascular, las variaciones de la producción de óxido nítrico, aumento de la expresión de agentes prehipertensivos como la endotelina-1, la rarefracción microvascular, la activación del sistema renina-angiotensina y el estrés oxidativo

The split property for quantum field theories in flat and curved spacetimes

The split property expresses a strong form of independence of spacelike separated regions in algebraic quantum field theory. In Minkowski spacetime, it can be proved under hypotheses of nuclearity. An expository account is given of nuclearity and the split property, and connections are drawn to the theory of quantum energy inequalities. In addition, a recent proof of the split property for quantum field theory in curved spacetimes is outlined, emphasising the essential ideas

Eurasian Arctic greening reveals teleconnections and the potential for novel ecosystems

Arctic warming has been linked to observed increases in tundra shrub cover and growth in recent decades on the basis of significant relationships between deciduous shrub growth/biomass and temperature. These vegetation trends have been linked to Arctic sea ice decline and thus to the sea ice/albedo feedback known as Arctic amplification. However, the interactions between climate, sea ice and tundra vegetation remain poorly understood. Here we reveal a 50- year growth response over a >100,000 km2 area to a rise in summer temperature for alder (Alnus) and willow (Salix), the most abundant shrub genera respectively at and north of the continental treeline. We demonstrate that whereas plant productivity is related to sea ice in late spring, the growing season peak responds to persistent synoptic-scale air masses over West Siberia associated with Fennoscandian weather systems through the Rossby wave train. Substrate is important for biomass accumulation, yet a strong correlation between growth and temperature encompasses all observed soil types. Vegetation is especially responsive to temperature in early summer. These results have significant implications for modelling present and future Low Arctic vegetation responses to climate change, and emphasize the potential for structurally novel ecosystems to emerge fromwithin the tundra zone.Vertaisarviointia edeltävä käsikirjoitu

A national survey of medical education fellowships

Purpose: The purpose of our study was to determine the prevalence, focus, time commitment, graduation requirements and programme evaluation methods of medical education fellowships throughout the United States. Medical education fellowships are defined as a single cohort of medical teaching faculty who participate in an extended faculty development programme. Methods: A 26-item online questionnaire was distributed to all US medical schools (n=127) in 2005 and 2006. The questionnaire asked each school if it had a medical education fellowship and the characteristics of the fellowship programme. Results: Almost half (n=55) of the participating schools (n=120, response rate 94.5 %) reported having fellowships. Duration (10–584 hours) and length (<1 month–48 months) varied; most focused on teaching skills, scholarly dissemination and curriculum design, and required the completion of a scholarly project. A majority collected participant satisfaction; few used other programme evaluation strategies. Conclusions: The number of medical education fellowships increased rapidly during the 1990s and 2000s. Across the US, programmes are similar in participant characteristics and curricular focus but unique in completion requirements. Fellowships collect limited programme evaluation data, indicating a need for better outcome data. These results provide benchmark data for those implementing or revising existing medical education fellowships

Data-as-a-Service Platform for Delivering Healthy Lifestyle and Preventive Medicine: Concept and Structure of the DAPHNE Project

Background: Overweight and obesity is related to many health problems and diseases. The current obesity epidemic, which is a major health problem, is closely related to a lack of physical activity, high levels of sedentary behavior, and increased energy intake; with evidence to show increasing incidence of these issues in the younger population. Tackling obesity and its comorbid conditions requires a holistic approach encompassing attention on physical activity, healthy diet, and behavioral activation in order to enable and maintain meaningful and long-term weight loss and weight maintenance. Objective: The objective of the Data-as-a-Service Platform for Healthy Lifestyle and Preventive Medicine (DAPHNE) project is to develop a breakthrough information communications technology (ICT) platform for tracking health, weight, physical activity, diet, lifestyle, and psychological components within health care systems, whereby the platform and clinical support is linked. Methods: The DAPHNE platform aims to deliver personalized guidance services for lifestyle management to the citizen/patient by means of (1) advanced sensors and mobile phone apps to acquire and store continuous/real-time data on lifestyle aspects, behavior, and surrounding environment; (2) individual models to monitor their health and fitness status; (3) intelligent data processing for the recognition of behavioral trends; and (4) specific services for personalized guidance on healthy lifestyle and disease prevention. It is well known that weight loss and maintenance of weight loss are particularly difficult. This tool will address some of the issues found with conventional treatment/advice in that it will collect data in real time, thereby reducing reliability issues known with recalling events once they have passed and will also allow adjustment of behavior through timely support and recommendations sent through the platform without the necessity of formal one-to-one visits between patient and clinician. Patient motivation/compliance is a particular issue with conventional weight loss regimes; DAPHNE aims to increase the individuals’ awareness of their own behavior and fosters their accountability. Results: The project has been funded and the research work has started. Results for the validation of the different components is due imminently. Conclusions: In contrast with previous existing solutions, the DAPHNE project tackles the obesity problem from a clinical point of view, designing the different interfaces for its use by patients (adults and children), physicians, and caregivers. A specific design for children and adolescent patients treated for obesity has been followed, guided by pediatric physicians at hospitals in Europe. The final clinical validation of the DAPHNE platform will be carried out in different European hospitals, testing the platform in both adolescents and adults

The edges of understanding

A culture's icons are a window onto its soul. Few would disagree that, in the culture of molecular biology that dominated much of the life sciences for the last third of the 20th century, the dominant icon was the double helix. In the present, post-modern, 'systems biology' era, however, it is, arguably, the hairball