116 research outputs found
SDSS J0349-0059 is a GW Virginis star
High speed photometric observations of the spectroscopically-discovered PG
1159 star SDSS J034917.41-005917.9 in 2007 and 2009 reveal a suite of pulsation
frequencies in the range of 1038 - 3323 microHz with amplitudes between 3.5 and
18.6 mmag. SDSS J034917.41-005917.9 is therefore a member of the GW Vir class
of pulsating pre-white dwarfs. We have identified 10 independent pulsation
frequencies that can be fitted by an asymptotic model with a constant period
spacing of 23.61 +/- 0.21 s, presumably associated with a sequence of l = 1
modes. The highest amplitude peak in the suite of frequencies shows evidence
for a triplet structure, with a frequency separation of 14.4 microHz. Five of
the identified frequencies do not fit the l = 1 sequence, but are, however,
well-modeled by an independent asymptotic sequence with a constant period
spacing of 11.66 +/- 0.13 s. It is unclear to which l mode these frequencies
belong.Comment: Accepted for publication in MNRAS; 5 pages, 6 figures and 4 table
On the spin modulated circular polarization from the intermediate polars NY Lup and IGRJ1509-6649
We report on high time resolution, high signal/noise, photo-polarimetry of
the intermediate polars NY Lup and IGRJ1509-6649. Our observations confirm the
detection and colour dependence of circular polarization from NY Lup and
additionally show a clear white dwarf, spin modulated signal. From our new high
signal/noise photometry we have unambiguously detected wavelength dependent
spin and beat periods and harmonics thereof. IGRJ1509-6649 is discovered to
also have a particularly strong spin modulated circularly polarized signal. It
appears double peaked through the I filter and single peaked through the B
filter, consistent with cyclotron emission from a white dwarf with a relatively
strong magnetic field.
We discuss the implied accretion geometries in these two systems and any
bearing this may have on the possible relationship with the connection between
polars and soft X-ray-emitting IPs. The relatively strong magnetic fields is
also suggestive of them being polar progenitors.Comment: 8 pages, 6 figures and 1 table. Accepted for publication in MNRA
Fourteen pathways between urban transportation and health: A conceptual model and literature review
Introduction: Transportation is an integral part of our daily lives, giving us access to people, education, jobs, services, and goods. Our transportation choices and patterns are influenced by four interrelated factors: the land use and built environment, infrastructure, available modes, and emerging technologies/disruptors. These factors influence how we can or choose to move ourselves and goods. In turn, these factors impact various exposures, lifestyles and health outcomes. /
Aim and methods: We developed a conceptual model to clarify the connections between transportation and health. We conducted a literature review focusing on publications from the past seven years. We complemented this with expert knowledge and synthesized information to summarize the health outcomes of transportation, along 14 identified pathways. /
Results: The pathways linking transportation to health include those that are beneficial, such as when transportation serves as means for social connectivity, independence, physical activity, and access. Some pathways link transportation to detrimental health outcomes from air pollution, road travel injuries, noise, stress, urban heat islands, contamination, climate change, community severance, and restricted green space, blue space, and aesthetics. Other possible effects may come from electromagnetic fields, but this is not definitive. We define each pathway and summarize its health outcomes. We show that transportation-related exposures and associated health outcomes, and their severity, can be influenced by inequity and intrinsic and extrinsic effect modifiers. /
Conclusions: While some pathways are widely discussed in the literature, others are new or under-researched. Our conceptual model can form the basis for future studies looking to explore the transportation-health nexus. We also propose the model as a tool to holistically assess the impact of transportation decisions on public health
Low mortality of people living with diabetes mellitus diagnosed with COVID-19 and managed at a field hospital in Western Cape Province, South Africa
Background. The novel coronavirus disease 2019 (COVID-19) was declared an international pandemic by the World Health Organization in March 2020. Throughout the pandemic, the association between diabetes mellitus (DM) and more severe COVID-19 has been well described internationally, with limited data, however, on South Africa (SA). The role of field hospitals in the management of patients with COVID-19 in SA has not yet been described. Objectives. To describe the mortality and morbidity of people living with DM (PLWD) and comorbid COVID-19, as well as to shed light on the role of intermediate facilities in managing DM and COVID-19 during the pandemic. Methods. This is a single-centre cross-sectional descriptive study that included all patients with confirmed COVID-19 and pre-existing or newly diagnosed DM (of any type) admitted to the Cape Town International Convention Centre (CTICC) Intermediate Care Bed Facility from June 2020 to August 2020. This study presents the profile of patients admitted to the CTICC, and reports on the clinical outcome of PLWD diagnosed with COVID-19, and additionally determines some associations between risk factors and death or escalation of care in this setting. Results. There were 1Â 447 admissions at the CTICC, with a total of 674 (46.6%) patients who had confirmed DM, of whom 125 (19%) were newly diagnosed diabetics and 550 (81%) had pre-existing DM. Included in this group were 57 referrals from the telemedicine platform â a platform that identified high-risk diabetic patients with COVID-19 in the community, and linked them directly to hospital inpatient care. Of the 674 PLWD admitted, 593 were discharged alive, 45 were escalated to tertiary hospital requiring advanced care and 36 died. PLWD who died were older, had more comorbidities (specifically chronic obstructive pulmonary disease, congestive cardiac failure and chronic kidney disease) and were more likely to be on insulin.Conclusions. In a resource-limited environment, interdisciplinary and interfacility collaboration ensured that complicated patients with DM and COVID-19 were successfully managed in a field hospital setting. Telemedicine offered a unique opportunity to identify high-risk patients in the community and link them to in-hospital monitoring and care. Future studies should explore ways to optimise this collaboration, as well as to explore possibilities for early identification and management of high-risk patients
The rapidly pulsating sdO star, SDSS J160043.6+074802.9
A spectroscopic analysis of SDSS J160043.6+074802.9, a binary system
containing a pulsating subdwarf-O (sdO) star with a late-type companion, yields
Teff = 70 000 +/- 5000 K and log g = 5.25 +/- 0.30, together with a most likely
type of K3V for the secondary star. We compare our results with atmospheric
parameters derived by Fontaine et al. (2008) and in the context of existing
evolution models for sdO stars. New and more extensive photometry is also
presented which recovers most, but not all, frequencies found in an earlier
paper. It therefore seems probable that some pulsation modes have variable
amplitudes. A non-adiabatic pulsation analysis of uniform metallicity sdO
models show those having log g > 5.3 to be more likely to be unstable and
capable of driving pulsation in the observed frequency range.Comment: 14 pages, 12 figures, accepted for publication in MNRAS, 2009
September
Possible detection of two giant extrasolar planets orbiting the eclipsing polar UZ Fornacis
We present new high-speed, multi-observatory, multi-instrument photometry of
the eclipsing polar UZ For in order to measure precise mid-eclipse times with
the aim of detecting any orbital period variations. When combined with
published eclipse times and archival data spanning ~27 years, we detect
departures from a linear and quadratic trend of ~60 s. The departures are
strongly suggestive of two cyclic variations of 16(3) and 5.25(25) years. The
two favoured mechanisms to drive the periodicities are either two giant
extrasolar planets as companions to the binary (with minimum masses of
6.3(1.5)M(Jupiter) and 7.7(1.2)M(Jupiter)) or a magnetic cycle mechanism (e.g.
Applegate's mechanism) of the secondary star. Applegate's mechanism would
require the entire radiant energy output of the secondary and would therefore
seem to be the least likely of the two, barring any further refinements in the
effect of magnetic fieilds (e.g. those of Lanza et al.). The two planet model
can provide realistic solutions but it does not quite capture all of the
eclipse times measurements. A highly eccentric orbit for the outer planet would
fit the data nicely, but we find that such a solution would be unstable. It is
also possible that the periodicities are driven by some combination of both
mechanisms. Further observations of this system are encouraged.Comment: 10 pages, 4 figures, 2 table
Development of intuitive rules: Evaluating the application of the dual-system framework to understanding children's intuitive reasoning
This is an author-created version of this article. The original source of publication is Psychon Bull Rev. 2006 Dec;13(6):935-53
The final publication is available at www.springerlink.com
Published version: http://dx.doi.org/10.3758/BF0321390
Maternally Orphaned Children and Intergenerational Concerns Associated with Breast Cancer Deaths among Women in Sub-Saharan Africa
Importance: Low breast cancer survival in sub-Saharan Africa's young population increases the likelihood that breast cancer deaths result in maternal orphans, ie, children (<18 years) losing their mother. Objective: To estimate the number of maternal orphans and their ages for every 100 breast cancer deaths in sub-Saharan African settings during 2014-2019 and to describe family concerns about the orphaned children. Design, Setting, and Participants: Deaths occurring between September 1, 2014, and July 1, 2019, in the African Breast Cancer-Disparities in Outcomes (ABC-DO) were examined in a cohort of women diagnosed with breast cancer during 2014-2017 at major cancer treatment hospitals in Namibia, Nigeria, Uganda, and Zambia. The cohort was actively followed up for vital status via a trimonthly mobile phone call to each woman or her next of kin (typically a partner, husband, or child). Main Outcomes and Measures: The number (Poisson counts) and ages of new orphans at the time of maternal death. Results: This cohort study found that a total of 795 deaths resulted in 964 new maternal orphans, with deaths occurring in women younger than 50 years accounting for 85% of the orphans. For every 100 deaths in women younger than 50 years, there were 210 new orphans (95% CI, 196-225) overall, with country-specific estimates of 189 in Nigerian, 180 in Namibian, 222 in Ugandan, and 247 in Zambian Black women. For every 100 deaths of the women at any age, there were 121 maternal orphans, 17% of whom were younger than 5 years, 32% aged 5 to 9 years, and 51% aged 10 to 17 years at the time of maternal death. In follow-up interviews, families' concerns for children's education and childcare were reported to be exacerbated by the financial expenses associated with cancer treatment. Conclusions and Relevance: This study provides evidence that the number of maternal orphans due to breast cancer exceeds the number of breast cancer deaths among women in sub-Saharan Africa. The intergenerational consequences associated with cancer deaths in sub-Saharan Africa appear to be large and support the need for continued action to improve survival
SDSS J160043.6+074802.9: a very rapid sdO pulsator
We report the serendipitous discovery of the Sloan Digital Sky Survey star,
SDSS J160043.6+074802.9 to be a very rapid pulsator. The variation is dominated
by a frequency near 8380 microHz (period = 119.33 s) with a large amplitude
(0.04 mag) and its first harmonic at 16760 microHz (59.66 s; 0.005 mag). In
between these frequencies, we find at least another 8 variations with periods
between 62 and 118 seconds and amplitudes between about 0.007 and 0.003 mag;
weaker oscillations might also be present. Preliminary spectrograms from the
performance verification phase of the Southern African Large Telescope indicate
that SDSS J160043.6+074802.9 is a spectroscopic binary consisting of an sdO
star and a late-type main-sequence companion. This makes it the first
unambiguous detection of such an sdO star to pulsate, and certainly the first
found to exhibit multi-frequency variations.Comment: 7 pages, 6 figures (figure 4 at reduced resolution, original
available on request). Accepted for publication in MNRA
High speed photometry of faint Cataclysmic Variables - VII. Targets selected from the Sloan Digital Sky Survey and the Catalina Real-time Transient Survey
We present high speed photometric observations of 20 faint cataclysmic
variables, selected from the Sloan Digital Sky Survey and Catalina catalogues.
Measurements are given of 15 new directly measured orbital periods, including
four eclipsing dwarf novae (SDSS0904+03, CSS0826-00, CSS1404-10 and
CSS1626-12), two new polars (CSS0810+00 and CSS1503-22) and two dwarf novae
with superhumps in quiescence (CSS0322+02 and CSS0826-00). Whilst most of the
dwarf novae presented here have periods below 2 h, SDSS0805+07 and SSS0617-36
have relatively long orbital periods of 5.489 and 3.440 h, respectively. The
double humped orbital modulations observed in SSS0221-26, CSS0345-01,
CSS1300+11 and CSS1443-17 are typical of low mass transfer rate dwarf novae.
The white dwarf primary of SDSS0919+08 is confirmed to have non-radial
oscillations and quasi-periodic oscillations were observed in the short-period
dwarf nova CSS1028-08 during outburst. We further report the detection of a new
nova-like variable (SDSS1519+06). The frequency distribution of orbital periods
of CVs in the Catalina survey has a high peak near ~80 min orbital period,
independently confirming that found by Gaensicke et al (2009) from SDSS
sources. We also observe a marked correlation between the median in the orbital
period distribution and the outburst class, in the sense that dwarf novae with
a single observed outburst (over the 5-year baseline of the CRTS coverage)
occur predominantly at shortest orbital period.Comment: 17 pages, 38 figures, accepted for publication in MNRA
- âŚ