Glaciological and Botanical Studies in Northern Ellesmere Island, 1959

The writers spent the summer season from May 18 to August 18 in the region of the Gilman Glacier, about 82°08'N, 70°57'W, in northeastern Ellesmere Island. The investigations undertaken under a Banting grant in aid were mainly complementary to the glaciological and botanical work of the expedition "Operation Hazen" sponsored by the Defence Research Board of Canada in 1957-8. The work of the party can be divided into four separate phases. After arrival at the Gilman Glacier camp of 1958 on May 18, supplies and equipment were moved from there to a new camp at the glacier snout. Some food and other stores were cached on a nunatak at the east side of the glacier. During this period all ablation and movement stakes that had been established in 1957-8 were visited by Sagar in order to gather ablation and accumulation data for 1958. By June 1, after the base camp had been established some 120 yards from the glacier snout, a series of meteorological and radiation observations was started, but a full program could not be begun until June 13 after all installations had been completed. During this second period the ablation stakes on the lower 8 miles of the glacier were examined. Additional ablation stakes were installed in the face of the snout. Botanical reconnaissance surveys of the snout area and neighbouring slopes were made by Powell. From June 13 to August 5 systematic series of synoptic and micro-meteorological readings were taken, but they were occasionally interrupted by other duties or by breakdown of equipment. Surveys of the glacier terminus, visits to a nearby drift glacier and to a small valley glacier were also made. Investigations of plant ecology and of plant communities in specific areas of the Lake Hazen-Gilman Glacier region were carried out. Less detailed meteorological observations only could be undertaken from August 6 to 17 after heavy and bulky equipment had been removed by helicopter to the USCGS icebreaker Westwind. Dr. G. F. Hattersley-Smith joined the party during this final period and took part in the glaciological work. All glacier stations were revisited in order to collect ablation data. Late summer plant and seed collections were made by Powell. The party left the glacier camp on August 18 and walked to the east shore of Lake Hazen where they were picked up by an R.C.A.F. plane on the 24th. A preliminary examination of the glaciological data allows one to draw certain conclusions. A direct comparison with some relevant records of 1957 and 1958 shows that accumulation of snow was approximately the same in each of the three years. In 1959 ablation was appreciably less than in 1958 and still more so than in 1957. The ablation season of 1959 was shorter and probably cooler than those of 1957 and 1958. Linear snout recession due to melting was relatively small in 1959. The present morphology of the glacier terminus indicates that a slight readvance of the ice during a whole year may be taking place at present. A close relationship between the amount of ablation over the lower part of the glacier and the solar radiation income was observed. It is hoped to present the results of the glaciological investigations in full in a later paper in which both the ablation process and the structural changes at the snout will be discussed. The botanical studies served to confirm distributional features noted before. Further ecological and phenological notes on flowering plants were taken and collections of all the species found were made. The collections of higher plants and less complete collections of mosses, lichens, and fungi have been deposited in the National Museum of Canada. Among the collections are a number of holarctic range extensions. The phenological data for 1959 as compared with those for 1958 support the evidence that the summer of 1959 was cooler than that of the previous years. ..

Multi-color Optical Variability of the TeV Blazar Mrk 501 in the Low-State

We report results based on the monitoring of the BL Lac object Mrk 501 in the optical (B, V and R) passbands from March to May 2000. Observations spread over 12 nights were carried out using 1.2 meter Mount Abu Telescope, India and 61 cm Telescope at Sobaeksan Astronomy Observatory, South Korea. The aim is to study the intra-day variability (IDV), short term variability and color variability in the low state of the source. We have detected flux variation of 0.05 mag in the R-band in time scale of 15 min in one night. In the B and V passbands, we have less data points and it is difficult to infer any IDVs. Short term flux variations are also observed in the V and R bands during the observing run. No significant variation in color (B$-$R) has been detected but (V$-$R) shows variation during the present observing run. Assuming the shortest observed time scale of variability (15 min) to represent the disk instability or pulsation at a distance of 5 Schwarschild radii from the black hole (BH), mass of the central BH is estimated $\sim$ 1.20 $\times$ 10$^{8} M_{\odot}$.Comment: 4 figures, 4 tables, Accepted for publication in New Astronom

Variation of the IMF

(abridged) The {stellar IMF} has been found to be essentially invariant. While some apparent differences are seen, the uncertainties inherent to this game do not allow a firm conclusion to be made that the IMF varies systematically with conditions. The IMF integrated over entire galaxies, however, is another matter. Chemical and photometric properties of various galaxies do hint at {galaxial IMFs} being steeper than the stellar IMF, as is also deduced from direct star-count analysis in the MW. These results are sensitive to the modelling of stellar populations and to corrections for stellar evolution, and are thus also uncertain. However, by realising that galaxies are made from dissolving star clusters, star clusters being viewed as {the fundamental building blocks of galaxies}, the result is found that galaxial IMFs must be significantly steeper than the stellar IMF, because the former results from a folding of the latter with the star-cluster mass function. Furthermore, this notion leads to the important insight that galaxial IMFs must vary with galaxy mass, and that the galaxial IMF is a strongly varying function of the star-formation history for galaxies that have assembled only a small mass in stars. Cosmological implications of this are discussed.Comment: 13 pages, to appear in IMFat50: The Initial Mass Function 50 years later, ed: E. Corbelli, F. Palla, and H. Zinnecker, Kluwer Academic Publishers; a meeting held at the Abbazia di Spineto, Tuscany, Italy -- May 16-20, 200

The IMF in Starbursts

The history of the IMF in starburst regions is reviewed. The IMFs are no longer believed to be top-heavy, although some superstar clusters, whether in starburst regions or not, could be. General observations of the IMF are discussed to put the starburst results in perspective. Observed IMF variations seem to suggest that the IMF varies a little with environment in the sense that denser and more massive clusters produce more massive stars, and perhaps more brown dwarfs too, compared to intermediate mass stars.Comment: 8 pages, to be published in ``Starbursts: from 30 Doradus to Lyman Break Galaxies,'' held at Institute of Astronomy, Cambridge University, UK, September 6-10, 2004. Kluwer Academic Publishers, edited by Richard de Grijs and Rosa M. Gonzalez Delgad

Chronic neuropsychiatric sequelae of SARS‐CoV‐2: Protocol and methods from the Alzheimer's Association Global Consortium

Introduction Coronavirus disease 2019 (COVID-19) has caused >3.5 million deaths worldwide and affected >160 million people. At least twice as many have been infected but remained asymptomatic or minimally symptomatic. COVID-19 includes central nervous system manifestations mediated by inflammation and cerebrovascular, anoxic, and/or viral neurotoxicity mechanisms. More than one third of patients with COVID-19 develop neurologic problems during the acute phase of the illness, including loss of sense of smell or taste, seizures, and stroke. Damage or functional changes to the brain may result in chronic sequelae. The risk of incident cognitive and neuropsychiatric complications appears independent from the severity of the original pulmonary illness. It behooves the scientific and medical community to attempt to understand the molecular and/or systemic factors linking COVID-19 to neurologic illness, both short and long term. Methods This article describes what is known so far in terms of links among COVID-19, the brain, neurological symptoms, and Alzheimer's disease (AD) and related dementias. We focus on risk factors and possible molecular, inflammatory, and viral mechanisms underlying neurological injury. We also provide a comprehensive description of the Alzheimer's Association Consortium on Chronic Neuropsychiatric Sequelae of SARS-CoV-2 infection (CNS SC2) harmonized methodology to address these questions using a worldwide network of researchers and institutions. Results Successful harmonization of designs and methods was achieved through a consensus process initially fragmented by specific interest groups (epidemiology, clinical assessments, cognitive evaluation, biomarkers, and neuroimaging). Conclusions from subcommittees were presented to the whole group and discussed extensively. Presently data collection is ongoing at 19 sites in 12 countries representing Asia, Africa, the Americas, and Europe. Discussion The Alzheimer's Association Global Consortium harmonized methodology is proposed as a model to study long-term neurocognitive sequelae of SARS-CoV-2 infection

A Meta-analysis of Multiple Myeloma Risk Regions in African and European Ancestry Populations Identifies Putatively Functional Loci

Genome-wide association studies (GWAS) in European populations have identified genetic risk variants associated with multiple myeloma (MM)

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

Mapping subnational HIV mortality in six Latin American countries with incomplete vital registration systems

BackgroundHuman immunodeficiency virus (HIV) remains a public health priority in Latin America. While the burden of HIV is historically concentrated in urban areas and high-risk groups, subnational estimates that cover multiple countries and years are missing. This paucity is partially due to incomplete vital registration (VR) systems and statistical challenges related to estimating mortality rates in areas with low numbers of HIV deaths. In this analysis, we address this gap and provide novel estimates of the HIV mortality rate and the number of HIV deaths by age group, sex, and municipality in Brazil, Colombia, Costa Rica, Ecuador, Guatemala, and Mexico.MethodsWe performed an ecological study using VR data ranging from 2000 to 2017, dependent on individual country data availability. We modeled HIV mortality using a Bayesian spatially explicit mixed-effects regression model that incorporates prior information on VR completeness. We calibrated our results to the Global Burden of Disease Study 2017.ResultsAll countries displayed over a 40-fold difference in HIV mortality between municipalities with the highest and lowest age-standardized HIV mortality rate in the last year of study for men, and over a 20-fold difference for women. Despite decreases in national HIV mortality in all countries-apart from Ecuador-across the period of study, we found broad variation in relative changes in HIV mortality at the municipality level and increasing relative inequality over time in all countries. In all six countries included in this analysis, 50% or more HIV deaths were concentrated in fewer than 10% of municipalities in the latest year of study. In addition, national age patterns reflected shifts in mortality to older age groups-the median age group among decedents ranged from 30 to 45years of age at the municipality level in Brazil, Colombia, and Mexico in 2017.ConclusionsOur subnational estimates of HIV mortality revealed significant spatial variation and diverging local trends in HIV mortality over time and by age. This analysis provides a framework for incorporating data and uncertainty from incomplete VR systems and can help guide more geographically precise public health intervention to support HIV-related care and reduce HIV-related deaths.Peer reviewe

Anemia prevalence in women of reproductive age in low- and middle-income countries between 2000 and 2018

Anemia is a globally widespread condition in women and is associated with reduced economic productivity and increased mortality worldwide. Here we map annual 2000–2018 geospatial estimates of anemia prevalence in women of reproductive age (15–49 years) across 82 low- and middle-income countries (LMICs), stratify anemia by severity and aggregate results to policy-relevant administrative and national levels. Additionally, we provide subnational disparity analyses to provide a comprehensive overview of anemia prevalence inequalities within these countries and predict progress toward the World Health Organization’s Global Nutrition Target (WHO GNT) to reduce anemia by half by 2030. Our results demonstrate widespread moderate improvements in overall anemia prevalence but identify only three LMICs with a high probability of achieving the WHO GNT by 2030 at a national scale, and no LMIC is expected to achieve the target in all their subnational administrative units. Our maps show where large within-country disparities occur, as well as areas likely to fall short of the WHO GNT, offering precision public health tools so that adequate resource allocation and subsequent interventions can be targeted to the most vulnerable populations.Peer reviewe