197 research outputs found
Target Selection for the SDSS-IV APOGEE-2 Survey
APOGEE-2 is a high-resolution, near-infrared spectroscopic survey observing
roughly 300,000 stars across the entire sky. It is the successor to APOGEE and
is part of the Sloan Digital Sky Survey IV (SDSS-IV). APOGEE-2 is expanding
upon APOGEE's goals of addressing critical questions of stellar astrophysics,
stellar populations, and Galactic chemodynamical evolution using (1) an
enhanced set of target types and (2) a second spectrograph at Las Campanas
Observatory in Chile. APOGEE-2 is targeting red giant branch (RGB) and red
clump (RC) stars, RR Lyrae, low-mass dwarf stars, young stellar objects, and
numerous other Milky Way and Local Group sources across the entire sky from
both hemispheres. In this paper, we describe the APOGEE-2 observational design,
target selection catalogs and algorithms, and the targeting-related
documentation included in the SDSS data releases.Comment: 19 pages, 6 figures. Accepted to A
Testing magnetically confined wind shock models for Beta Cep using XMM-Newton and Chandra phase-resolved X-ray observations
(abridged) We have performed a set of phase-resolved X-ray observations of
the magnetic B star Beta Cep, for which theoretical models predict the presence
of a confined wind emitting X-rays from stationary shocks.
We obtained four observations spaced in rotational phase with XMM-Newton and
with Chandra. A detailed analysis of the data was performed to derive both
photometric and spectral parameters from the EPIC data, searching for
rotational modulation, and to derive the location of the X-ray plasma from the
line ratios in the He-like triplets of N, O and Ne from the RGS data. The LETG
data were used to constrain the presence of bulk motions in the plasma.
The strong rotational modulation predicted by the early, static magnetically
confined wind model for the X-ray emission is not observed in Beta Cep. The
small modulation present goes in the opposite direction, pointing to the
absence of any optically thick disk of neutral material, and showing a
modulation consistent with the later, dynamic models of magnetically confined
wind models in B stars. The lack of observed bulk motion points to the plasma
being confined by a magnetic field, but the low plasma temperature and lack of
any flaring show that the plasma is not heated by magnetic reconnection.
Therefore, the observations point to X-ray emission from shocks in a
magnetically confined wind, with no evidence of an optically thick, dense disk
at the magnetic equatorComment: Accepted for publication in Astronomy & Astrophysic
A multicentre matched case control study of risk factors for Preeclampsia in healthy women in Pakistan
<p>Abstract</p> <p>Background</p> <p>Preeclampsia is one of the leading causes of maternal and perinatal morbidity and mortality world-wide. The risk for developing preeclampsia varies depending on the underlying mechanism. Because the disorder is heterogeneous, the pathogenesis can differ in women with various risk factors. Understanding these mechanisms of disease responsible for preeclampsia as well as risk assessment is still a major challenge. The aim of this study was to determine the risk factors associated with preeclampsia, in healthy women in maternity hospitals of Karachi and Rawalpindi.</p> <p>Methods</p> <p>We conducted a hospital based matched case-control study to assess the factors associated with preeclampsia in Karachi and Rawalpindi, from January 2006 to December 2007. 131 hospital-reported cases of PE and 262 controls without history of preeclampsia were enrolled within 3 days of delivery. Cases and controls were matched on the hospital, day of delivery and parity. Potential risk factors for preeclampsia were ascertained during in-person postpartum interviews using a structured questionnaire and by medical record abstraction. Conditional logistic regression was used to estimate matched odds ratios (ORs) and 95% confidence intervals (95% CIs).</p> <p>Results</p> <p>In multivariate analysis, women having a family history of hypertension (adjusted OR 2.06, 95% CI; 1.27-3.35), gestational diabetes (adjusted OR 6.57, 95% CI; 1.94 -22.25), pre-gestational diabetes (adjusted OR 7.36, 95% CI; 1.37-33.66) and mental stress during pregnancy (adjusted OR 1.32; 95% CI; 1.19-1.46, for each 5 unit increase in Perceived stress scale score) were at increased risk of preeclampsia. However, high body mass index, maternal age, urinary tract infection, use of condoms prior to index pregnancy and sociodemographic factors were not associated with higher risk of having preeclampsia.</p> <p>Conclusions</p> <p>Development of preeclampsia was associated with gestational diabetes, pregestational diabetes, family history of hypertension and mental stress during pregnancy. These factors can be used as a screening tool for preeclampsia prediction. Identification of the above mentioned predictors would enhance the ability to diagnose and monitor women likely to develop preeclampsia before the onset of disease for timely interventions and better maternal and fetal outcomes.</p
X-Ray Spectroscopy of Stars
(abridged) Non-degenerate stars of essentially all spectral classes are soft
X-ray sources. Low-mass stars on the cooler part of the main sequence and their
pre-main sequence predecessors define the dominant stellar population in the
galaxy by number. Their X-ray spectra are reminiscent, in the broadest sense,
of X-ray spectra from the solar corona. X-ray emission from cool stars is
indeed ascribed to magnetically trapped hot gas analogous to the solar coronal
plasma. Coronal structure, its thermal stratification and geometric extent can
be interpreted based on various spectral diagnostics. New features have been
identified in pre-main sequence stars; some of these may be related to
accretion shocks on the stellar surface, fluorescence on circumstellar disks
due to X-ray irradiation, or shock heating in stellar outflows. Massive, hot
stars clearly dominate the interaction with the galactic interstellar medium:
they are the main sources of ionizing radiation, mechanical energy and chemical
enrichment in galaxies. High-energy emission permits to probe some of the most
important processes at work in these stars, and put constraints on their most
peculiar feature: the stellar wind. Here, we review recent advances in our
understanding of cool and hot stars through the study of X-ray spectra, in
particular high-resolution spectra now available from XMM-Newton and Chandra.
We address issues related to coronal structure, flares, the composition of
coronal plasma, X-ray production in accretion streams and outflows, X-rays from
single OB-type stars, massive binaries, magnetic hot objects and evolved WR
stars.Comment: accepted for Astron. Astrophys. Rev., 98 journal pages, 30 figures
(partly multiple); some corrections made after proof stag
Risk of high-grade serous ovarian cancer associated with pelvic inflammatory disease, parity and breast cancer
Background: Ovarian carcinoma is not a single disease, but rather a collection of subtypes with differing molecular properties and risk profiles. The most common of these, and the subject of this work, is high-grade serous ovarian carcinoma (HGSC).
Methods: In this population-based study we identified a cohort of 441,382 women resident in Western Australia who had ever been admitted to hospital in the State. Of these, 454 were diagnosed with HGSC. We used Cox regression to derive hazard ratios (HRs) comparing the risk of disease in women who had each of a range of medical diagnoses and surgical procedures with women who did not.
Results: We found an increased risk of HGSC associated with a diagnosis of pelvic inflammatory disease (PID) (HR 1.47, 95% CI 1.04–2.07) but not with a diagnosis of infertility or endometriosis with HRs of 1.12 (95% CI 0.73–1.71) and 0.82 (95% CI 0.55–1.22) respectively. A personal history of breast cancer was associated with a three-fold increase in the rate of HGSC. Increased parity was associated with a reduced risk of HGSC in women without a personal history of breast cancer (HR 0.57; 95% CI 0.44-0.73), but not in women with a personal history of breast cancer (HR 1.48; 95% CI 0.74–2.95).
Conclusions: Our finding of an increased risk of HGSC associated with PID lends support to the hypothesis that inflammatory processes may be involved in the etiology of HGSC
Transhiatal vs extended transthoracic resection in oesophageal carcinoma: patients' utilities and treatment preferences
To assess patients' utilities for health state outcomes after transhiatal or transthoracic oesophagectomy for oesophageal cancer and to investigate the patients' treatment preferences for either procedure. The study group consisted of 48 patients who had undergone either transhiatal or transthoracic oesophagectomy. In an interview they were presented with eight possible health states following oesophagectomy. Visual Analogue Scale and standard gamble techniques were used to measure utilities. Treatment preference for either transhiatal or transthoracic oesophagectomy was assessed. Highest scores were found for the patients' own current health state (Visual Analogue Scale: 0.77; standard gamble: 0.97). Lowest scores were elicited for the health state ‘irresectable tumour’ (Visual Analogue Scale: 0.13; standard gamble: 0.34). The Visual Analogue Scale method produced lower estimates (P<0.001) than the standard gamble method for all health states. Most patient characteristics and clinical factors did not correlate with the utilities. Ninety-five per cent of patients who underwent a transthoracic procedure and 52% of patients who underwent a transhiatal resection would prefer the transthoracic treatment. No significant associations between any patient characteristics or clinical characteristics and treatment preference were found. Utilities after transhiatal or transthoracic oesophagectomy were robust because they generally did not vary by patient or clinical characteristics. Overall, most patients preferred the transthoracic procedure
To formalize or not to formalize: women entrepreneurs’ sensemaking of business registration in the context of Nepal
Despite the depiction of decisions to formalize informal firms as rational and ethical, many entrepreneurs in developing countries continue to operate informally regardless of its perceived illicit status. While existing research on why entrepreneurs choose informality emphasizes the economic costs and benefits of such decisions, this often overlooks the realities of the informal economy and the constraints which marginal populations—particularly women—face. In this paper, we use institutional theory and sensemaking to understand the experiences of women in the informal economy and what formalization means to them. We use a qualitative approach to collect data from 90 women entrepreneurs in three different cities in Nepal. In our findings, we identify three groups of women with distinctive understandings of formalization—business sustainability, livelihood sufficiency and strategic alignment. Their interpretation of formalization reveals the complex, dynamic, and cyclical nature of formalization decisions. Decisions are also guided by the optimization of social and emotional logics, whereby formalization is conceived differently depending on different life stages, experiences within the informal economy and wider socio-cultural contexts. Our findings highlight the ethical implications of formalization where being a ‘good citizen’, rather than complying with formal rules and regulations, is about attuning to and fitting in with socially prescribed roles. Our research provides a nuanced view of formalization decisions, challenging idealized and ethical notions of formalization as a desired end state
Becoming a mentor: The impact of training and the experience of mentoring university students on the autism spectrum
While it is widely recognised that the number of young adults diagnosed with Autism Spectrum Disoders (ASD) is increasing, there is currently limited understanding of effective support for the transition to adulthood. One approach gaining increasing attention in the university sector is specialised peer mentoring. The aim of this inductive study was to understand the impact of peer mentor training on seven student mentors working with university students with an ASD. Kirkpatrick’s model framed a mixed methods evaluation of the mentors’ training and description of their experience. Overall, the training was well received by the mentors, who reported on average a 29% increase in their ASD knowledge following the training. Results from the semi-structured interviews conducted three months after the training, found that mentors felt that the general ASD knowledge they gained as part of their training had been essential to their role. The mentors described how their overall experience had been positive and reported that the training and support provided to them was pivotal to their ability to succeed in as peer mentors to students with ASD. This study provides feedback in support of specialist peer-mentoring programs for university students and can inform recommendations for future programs and research
ACE Observations of the Bastille Day 2000 Interplanetary Disturbances
We present ACE observations for the six-day period encompassing the Bastille Day 2000 solar activity. A high level of transient activity at 1 AU, including ICME-driven shocks, magnetic clouds, shock-accelerated energetic particle populations, and solar energetic ions and electrons, are described. We present thermal ion composition signatures for ICMEs and magnetic clouds from which we derive electron temperatures at the source of the disturbances and we describe additional enhancements in some ion species that are clearly related to the transient source. We describe shock acceleration of 0.3–2.0 MeV nucl −1 protons and minor ions and the relative inability of some of the shocks to accelerate significant energetic ion populations near 1 AU. We report the characteristics of < 20 MeV nucl −1 solar energetic ions and < 0.32 MeV electrons and attempt to relate the release of energetic electrons to particular source regions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43716/1/11207_2004_Article_380058.pd
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