250 research outputs found
Large-scale shock-ionized and photo-ionized gas in M83: the impact of star formation
We investigate the ionization structure of the nebular gas in M83 using the
line diagnostic diagram, [O III](5007 \degA)/H{\beta} vs. [S II](6716 \deg
A+6731 \deg A)/H{\alpha} with the newly available narrowband images from the
Wide Field Camera 3 (WFC3) of the Hubble Space Telescope (HST). We produce the
diagnostic diagram on a pixel-by-pixel (0.2" x 0.2") basis and compare it with
several photo- and shock-ionization models. For the photo-ionized gas, we
observe a gradual increase of the log([O III]/H{\beta}) ratios from the center
to the spiral arm, consistent with the metallicity gradient, as the H II
regions go from super solar abundance to roughly solar abundance from the
center out. Using the diagnostic diagram, we separate the photo-ionized from
the shock-ionized component of the gas. We find that the shock-ionized
H{\alpha} emission ranges from ~2% to about 15-33% of the total, depending on
the separation criteria used. An interesting feature in the diagnostic diagram
is an horizontal distribution around log([O III]/H{\beta}) ~ 0. This feature is
well fit by a shock-ionization model with 2.0 Z\odot metallicity and shock
velocities in the range of 250 km/s to 350 km/s. A low velocity shock
component, < 200 km/s, is also detected, and is spatially located at the
boundary between the outer ring and the spiral arm. The low velocity shock
component can be due to : 1) supernova remnants located nearby, 2) dynamical
interaction between the outer ring and the spiral arm, 3) abnormal line ratios
from extreme local dust extinction. The current data do not enable us to
distinguish among those three possible interpretations. Our main conclusion is
that, even at the HST resolution, the shocked gas represents a small fraction
of the total ionized gas emission at less than 33% of the total. However, it
accounts for virtually all of the mechanical energy produced by the central
starburst in M83.Comment: Accepted for publication in ApJ. aastex preprint 12pt, 21 pages, 13
figure
Rapid phase-shift reversal on a Jamaican coral reef
Abstract Many Caribbean reefs have experienced a phase-shift in community structure, the principle features being a decline in coral cover and an increase in macroalgal biomass. However, one Jamaican reef-Dairy Bull on the north shore near Discovery Bay-is once again dominated by scleractinian corals and several key species have returned. Living coral cover at 6-8 m depth at Dairy Bull has doubled over the past 9 years and is now 11% by January 2004. During this time the cover of macroalgae decreased by 90%, from 45 to 6%. We speculate that long-lived colonies of Montastraea annularis may have facilitated the recovery of this reef by providing structural refugia
Control of intestinal stem cell function and proliferation by mitochondrial pyruvate metabolism.
Most differentiated cells convert glucose to pyruvate in the cytosol through glycolysis, followed by pyruvate oxidation in the mitochondria. These processes are linked by the mitochondrial pyruvate carrier (MPC), which is required for efficient mitochondrial pyruvate uptake. In contrast, proliferative cells, including many cancer and stem cells, perform glycolysis robustly but limit fractional mitochondrial pyruvate oxidation. We sought to understand the role this transition from glycolysis to pyruvate oxidation plays in stem cell maintenance and differentiation. Loss of the MPC in Lgr5-EGFP-positive stem cells, or treatment of intestinal organoids with an MPC inhibitor, increases proliferation and expands the stem cell compartment. Similarly, genetic deletion of the MPC in Drosophila intestinal stem cells also increases proliferation, whereas MPC overexpression suppresses stem cell proliferation. These data demonstrate that limiting mitochondrial pyruvate metabolism is necessary and sufficient to maintain the proliferation of intestinal stem cells
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe
The preponderance of matter over antimatter in the early Universe, the
dynamics of the supernova bursts that produced the heavy elements necessary for
life and whether protons eventually decay --- these mysteries at the forefront
of particle physics and astrophysics are key to understanding the early
evolution of our Universe, its current state and its eventual fate. The
Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed
plan for a world-class experiment dedicated to addressing these questions. LBNE
is conceived around three central components: (1) a new, high-intensity
neutrino source generated from a megawatt-class proton accelerator at Fermi
National Accelerator Laboratory, (2) a near neutrino detector just downstream
of the source, and (3) a massive liquid argon time-projection chamber deployed
as a far detector deep underground at the Sanford Underground Research
Facility. This facility, located at the site of the former Homestake Mine in
Lead, South Dakota, is approximately 1,300 km from the neutrino source at
Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino
charge-parity symmetry violation and mass ordering effects. This ambitious yet
cost-effective design incorporates scalability and flexibility and can
accommodate a variety of upgrades and contributions. With its exceptional
combination of experimental configuration, technical capabilities, and
potential for transformative discoveries, LBNE promises to be a vital facility
for the field of particle physics worldwide, providing physicists from around
the globe with opportunities to collaborate in a twenty to thirty year program
of exciting science. In this document we provide a comprehensive overview of
LBNE's scientific objectives, its place in the landscape of neutrino physics
worldwide, the technologies it will incorporate and the capabilities it will
possess.Comment: Major update of previous version. This is the reference document for
LBNE science program and current status. Chapters 1, 3, and 9 provide a
comprehensive overview of LBNE's scientific objectives, its place in the
landscape of neutrino physics worldwide, the technologies it will incorporate
and the capabilities it will possess. 288 pages, 116 figure
Estimating the costs of school closure for mitigating an influenza pandemic
BACKGROUND: School closure is a key component of many countries' plans to mitigate the effect of an influenza pandemic. Although a number of studies have suggested that such a policy might reduce the incidence, there are no published studies of the cost of such policies. This study attempts to fill this knowledge gap METHODS: School closure is expected to lead to significant work absenteeism of working parents who are likely to be the main care givers to their dependent children at home. The cost of absenteeism due to school closure is calculated as the paid productivity loss of parental absenteeism during the period of school closure. The cost is estimated from societal perspective using a nationally representative survey. RESULTS: The results show that overall about 16% of the workforce is likely to be the main caregiver for dependent children and therefore likely to take absenteeism. This rises to 30% in the health and social care sector, as a large proportion of the workforce are women. The estimated costs of school closure are significant, at 0.2 pounds bn - 1.2 pounds bn per week. School closure is likely to significantly exacerbate the pressures on the health system through staff absenteeism. CONCLUSION: The estimates of school closure associated absenteeism and the projected cost would be useful for pandemic planning for business continuity, and for cost effectiveness evaluation of different pandemic influenza mitigation strategies
A Connection between Colony Biomass and Death in Caribbean Reef-Building Corals
Increased sea-surface temperatures linked to warming climate threaten coral reef ecosystems globally. To better understand how corals and their endosymbiotic dinoflagellates (Symbiodinium spp.) respond to environmental change, tissue biomass and Symbiodinium density of seven coral species were measured on various reefs approximately every four months for up to thirteen years in the Upper Florida Keys, United States (1994–2007), eleven years in the Exuma Cays, Bahamas (1995–2006), and four years in Puerto Morelos, Mexico (2003–2007). For six out of seven coral species, tissue biomass correlated with Symbiodinium density. Within a particular coral species, tissue biomasses and Symbiodinium densities varied regionally according to the following trends: Mexico≥Florida Keys≥Bahamas. Average tissue biomasses and symbiont cell densities were generally higher in shallow habitats (1–4 m) compared to deeper-dwelling conspecifics (12–15 m). Most colonies that were sampled displayed seasonal fluctuations in biomass and endosymbiont density related to annual temperature variations. During the bleaching episodes of 1998 and 2005, five out of seven species that were exposed to unusually high temperatures exhibited significant decreases in symbiotic algae that, in certain cases, preceded further decreases in tissue biomass. Following bleaching, Montastraea spp. colonies with low relative biomass levels died, whereas colonies with higher biomass levels survived. Bleaching- or disease-associated mortality was also observed in Acropora cervicornis colonies; compared to A. palmata, all A. cervicornis colonies experienced low biomass values. Such patterns suggest that Montastraea spp. and possibly other coral species with relatively low biomass experience increased susceptibility to death following bleaching or other stressors than do conspecifics with higher tissue biomass levels
Psicología social y moral de COVID-19 en 69 países
La pandemia de COVID-19 ha afectado a todos los ámbitos de la vida humana, incluido el tejido económico y social de las sociedades. Una de las estrategias centrales para gestionar la salud pública a lo largo de la pandemia ha sido el envío de mensajes persuasivos y el cambio de comportamiento colectivo. Para ayudar a los estudiosos a comprender mejor la psicología social y moral que subyace al comportamiento en materia de salud pública, presentamos un conjunto de datos compuesto por 51.404 individuos de 69 países. Este conjunto de datos se recopiló para el proyecto de la Colaboración Internacional en Psicología Social y Moral de COVID-19 (ICSMP COVID-19). Esta encuesta de ciencias sociales invitó a participantes de todo el mundo a completar una serie de medidas morales y psicológicas y actitudes de salud pública sobre COVID-19 durante una fase temprana de la pandemia de COVID-19 (entre abril y junio de 2020). La encuesta incluía siete grandes categorías de preguntas: Creencias sobre COVID-19 y conductas de cumplimiento; identidad y actitudes sociales; ideología; salud y bienestar; creencias morales y motivación; rasgos de personalidad; y variables demográficas. Presentamos los datos brutos y depurados, junto con todos los materiales de la encuesta, las visualizaciones de los datos y las evaluaciones psicométricas de las variables clave.The COVID-19 pandemic has affected all domains of human life, including the economic and social fabric of societies. One of the central strategies for managing public health throughout the pandemic has been through persuasive messaging and collective behaviour change. To help scholars better understand the social and moral psychology behind public health behaviour, we present a dataset comprising of 51,404 individuals from 69 countries. This dataset was collected for the International Collaboration on Social & Moral Psychology of COVID-19 project (ICSMP COVID-19). This social science survey invited participants around the world to complete a series of moral and psychological measures and public health attitudes about COVID-19 during an early phase of the COVID-19 pandemic (between April and June 2020). The survey included seven broad categories of questions: COVID-19 beliefs and compliance behaviours; identity and social attitudes; ideology; health and well-being; moral beliefs and motivation; personality traits; and demographic variables. We report both raw and cleaned data, along with all survey materials, data visualisations, and psychometric evaluations of key variables
Combined Forward-Backward Asymmetry Measurements in Top-Antitop Quark Production at the Tevatron
The CDF and D0 experiments at the Fermilab Tevatron have measured the asymmetry between yields of forward- and backward-produced top and antitop quarks based on their rapidity difference and the asymmetry between their decay leptons. These measurements use the full data sets collected in proton-antiproton collisions at a center-of-mass energy of TeV. We report the results of combinations of the inclusive asymmetries and their differential dependencies on relevant kinematic quantities. The combined inclusive asymmetry is . The combined inclusive and differential asymmetries are consistent with recent standard model predictions
National identity predicts public health support during a global pandemic (vol 13, 517, 2022) : National identity predicts public health support during a global pandemic (Nature Communications, (2022), 13, 1, (517), 10.1038/s41467-021-27668-9)
Publisher Copyright: © The Author(s) 2022.In this article the author name ‘Agustin Ibanez’ was incorrectly written as ‘Augustin Ibanez’. The original article has been corrected.Peer reviewe
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National identity predicts public health support during a global pandemic.
Changing collective behaviour and supporting non-pharmaceutical interventions is an important component in mitigating virus transmission during a pandemic. In a large international collaboration (Study 1, N = 49,968 across 67 countries), we investigated self-reported factors associated with public health behaviours (e.g., spatial distancing and stricter hygiene) and endorsed public policy interventions (e.g., closing bars and restaurants) during the early stage of the COVID-19 pandemic (April-May 2020). Respondents who reported identifying more strongly with their nation consistently reported greater engagement in public health behaviours and support for public health policies. Results were similar for representative and non-representative national samples. Study 2 (N = 42 countries) conceptually replicated the central finding using aggregate indices of national identity (obtained using the World Values Survey) and a measure of actual behaviour change during the pandemic (obtained from Google mobility reports). Higher levels of national identification prior to the pandemic predicted lower mobility during the early stage of the pandemic (r = -0.40). We discuss the potential implications of links between national identity, leadership, and public health for managing COVID-19 and future pandemics
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