Probing the distinct chemical history of the Milky Way halo and old thick disk through HESP-GOMPA survey

Recent studies of the time-resolved Milky Way formation using asteroseismology have shown that thick disk stars could be very old (0.8 Gyr after the Big Bang, even older than the inner halo). Additionally, thick disk stars are expected to have formed from a mixed gas and offer a better site to study the chemical enrichment history. Here, we present abundance trends for about 65 metal-poor stars (•3.1 < [Fe/H] < •1.8) that are kinematically separated into thick disk, and halo, observed with the HESP spectrograph installed at HCT telescope. The sample includes 40 newly identified stars combined with 25 stars from an earlier HESP-GOMPA survey and a compilation from literature. Generally, thick disk stars show less scatter than the halo stars. The abundance trend in [Mg/Fe] as a function of metallicity remains flat for thick disk stars, indicating similar enrichment history and well-mixed ISM with only massive star contribution, whereas the halo stars show a large scatter and a declining trend in [Mg/Fe] as a function of metallicity. The [Eu/Mg] trend show a mildly increasing trend indicating some delay in the production of Eu as compared to Mg, in both halo and the thick disk stars. The scatter in the abundance trend is larger in the halo as compared to thick disk stars, indicating that the halo is formed from accretion of multiple stellar systems

Decoding the compositions of four bright rr-process-enhanced stars

There has been a concerted effort in recent years to identify the astrophysical sites of the $r$-process that can operate early in the Galaxy. The discovery of many $r$-process-enhanced (RPE) stars (especially by the $R$-process Alliance collaboration) has significantly accelerated this effort. However, only limited data exist on the detailed elemental abundances covering the primary neutron-capture peaks. Subtle differences in the structure of the $r$-process pattern, such as the relative abundances of elements in the third peak, in particular, are expected to constrain the $r$-process sites further. Here, we present a detailed elemental-abundance analysis of four bright RPE stars selected from the HESP-GOMPA survey. Observations were carried out with the 10-m class telescope Gran Telescopio Canarias (GTC), Spain. The high spectral signal-to-noise ratios obtained allow us to derive abundances for 20 neutron-capture elements, including the third $r$-process peak element osmium (Os). We detect thorium (Th) in two stars, which we use to estimate their ages. We discuss the metallicity evolution of Mg, Sr, Ba, Eu, Os, and Th in $r$-II and $r$-I stars, based on a compilation of RPE stars from the literature. The strontium (Sr) abundance trend with respect to europium (Eu) suggests the need for an additional production site for Sr (similar to several earlier studies); this requirement could be milder for yttrium (Y) and zirconium (Zr). We also show that there could be some time delay between $r$-II and $r$-I star formation, based on the Mg/Th abundance ratios.Comment: 33 pages, 22 figures, Accepted for publication in MNRA

Primary intracranial malignant melanoma in an adolescent female: a case report

Abstract Background Primary central nervous system melanoma is an extremely rare entity and even rarer in children and adolescents as compared to adults. It is often difficult to consider a diagnosis of intracranial melanoma pre-operatively without any clinical evidence of neurocutaneous melanosis. Case presentation Herein, a case of primary melanoma of the brain is reported in a 17-year-old female who presented with headache, vomiting, and focal neurological deficit in the form of left-sided facial palsy and limb weakness. A contrast-enhanced computed tomography of head was performed which revealed a heterogeneously hyperattenuating mass lesion at left gangliocapsular region showing peripheral enhancement with internal non-enhancing cystic component. The patient underwent left frontotemporal craniotomy. The diagnosis was made on histopathological examination, which showed an invasive tumor comprising of epithelioid to spindled cells arranged in sheets, nests, and singly scattered. The special stains and immunohistochemical markers proved very helpful in establishing the diagnosis. Conclusions The case highlights the uncommon occurrence of primary intracranial melanoma in the pediatric age group, the perplexing histological features, and the rapid and fatal course

The impact of air pollution on deaths, disease burden, and life expectancy across the states of India: the Global Burden of Disease Study 2017

Summary: Background: Air pollution is a major planetary health risk, with India estimated to have some of the worst levels globally. To inform action at subnational levels in India, we estimated the exposure to air pollution and its impact on deaths, disease burden, and life expectancy in every state of India in 2017. Methods: We estimated exposure to air pollution, including ambient particulate matter pollution, defined as the annual average gridded concentration of PM2.5, and household air pollution, defined as percentage of households using solid cooking fuels and the corresponding exposure to PM2.5, across the states of India using accessible data from multiple sources as part of the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017. The states were categorised into three Socio-demographic Index (SDI) levels as calculated by GBD 2017 on the basis of lag-distributed per-capita income, mean education in people aged 15 years or older, and total fertility rate in people younger than 25 years. We estimated deaths and disability-adjusted life-years (DALYs) attributable to air pollution exposure, on the basis of exposure–response relationships from the published literature, as assessed in GBD 2017; the proportion of total global air pollution DALYs in India; and what the life expectancy would have been in each state of India if air pollution levels had been less than the minimum level causing health loss. Findings: The annual population-weighted mean exposure to ambient particulate matter PM2·5 in India was 89·9 μg/m3 (95% uncertainty interval [UI] 67·0–112·0) in 2017. Most states, and 76·8% of the population of India, were exposed to annual population-weighted mean PM2·5 greater than 40 μg/m3, which is the limit recommended by the National Ambient Air Quality Standards in India. Delhi had the highest annual population-weighted mean PM2·5 in 2017, followed by Uttar Pradesh, Bihar, and Haryana in north India, all with mean values greater than 125 μg/m3. The proportion of population using solid fuels in India was 55·5% (54·8–56·2) in 2017, which exceeded 75% in the low SDI states of Bihar, Jharkhand, and Odisha. 1·24 million (1·09–1·39) deaths in India in 2017, which were 12·5% of the total deaths, were attributable to air pollution, including 0·67 million (0·55–0·79) from ambient particulate matter pollution and 0·48 million (0·39–0·58) from household air pollution. Of these deaths attributable to air pollution, 51·4% were in people younger than 70 years. India contributed 18·1% of the global population but had 26·2% of the global air pollution DALYs in 2017. The ambient particulate matter pollution DALY rate was highest in the north Indian states of Uttar Pradesh, Haryana, Delhi, Punjab, and Rajasthan, spread across the three SDI state groups, and the household air pollution DALY rate was highest in the low SDI states of Chhattisgarh, Rajasthan, Madhya Pradesh, and Assam in north and northeast India. We estimated that if the air pollution level in India were less than the minimum causing health loss, the average life expectancy in 2017 would have been higher by 1·7 years (1·6–1·9), with this increase exceeding 2 years in the north Indian states of Rajasthan, Uttar Pradesh, and Haryana. Interpretation: India has disproportionately high mortality and disease burden due to air pollution. This burden is generally highest in the low SDI states of north India. Reducing the substantial avoidable deaths and disease burden from this major environmental risk is dependent on rapid deployment of effective multisectoral policies throughout India that are commensurate with the magnitude of air pollution in each state. Funding: Bill & Melinda Gates Foundation; and Indian Council of Medical Research, Department of Health Research, Ministry of Health and Family Welfare, Government of India