4,498 research outputs found
Orbital motion of the young brown dwarf companion TWA 5 B
With more adaptive optics images available, we aim at detecting orbital
motion for the first time in the system TWA 5 A+B. We measured separation and
position angle between TWA 5 A and B in each high-resolution image available
and followed their change in time, because B should orbit around A. The
astrometric measurement precision is about one milli arc sec. With ten year
difference in epoch, we can clearly detect orbital motion of B around A, a
decrease in separation by ~ 0.0054 arc sec per year and a decrease in position
angle by ~ 0.26 degrees per year. TWA 5 B is a brown dwarf with ~ 25 Jupiter
masses (Neuh\"auser et al. 2000), but having large error bars (4 to 145 Jupiter
masses, Neuh\"auser et al. 2009). Given its large projected separation from the
primary star, ~ 86 AU, and its young age ~ 10 Myrs), it has probably formed
star-like, and would then be a brown dwarf companion. Given the relatively
large changes in separation and position angle between TWA 5 A and B, we can
conclude that they orbit around each other on an eccentric orbit. Some evidence
is found for a curvature in the orbital motion of B around A - most consistent
with an elliptic (e=0.45) orbit. Residuals around the best-fit ellipse are
detected and show a small-amplitude (~ 18 mas) periodic sinusoid with ~ 5.7 yr
period, i.e., fully consistent with the orbit of the inner close pair TWA 5
Aa+b. Measuring these residuals caused by the photocenter wobble - even in
unresolved images - can yield the total mass of the inner pair, so can test
theoretical pre-main sequence models.Comment: 6 pages, 4 figures, accepted for publication in A&A; corrected typo
in amplitude below Fig.
Approaches to the development of new mental well-being screening tools for Indigenous peoples: a systematic mixed studies review protocol
Introduction: Indigenous peoples' world views are intricately interrelated and interconnected with those of their communities and the environments where they live. Consequently, Indigenous peoples have a holistic view of their health, which contrasts with the dominant Western biomedical paradigm. However, the mental well-being of Indigenous peoples is predominately screened using tools developed using the Western paradigm that may not be culturally appropriate. The objective of this systematic mixed studies review (SMSR) is to assess the extent of the literature related to approaches used to develop new tools to screen the mental well-being of Indigenous adults.
Methods and analysis: This SMSR will be conducted in accordance with the method proposed by Pluye et al. It will include studies that describe the development of any type of tool or approach to screen for mental well-being in Indigenous adults, globally. Searches will be limited to the English language and literature published since January 2000. Databases to be searched include: CINAHL, Medline, PsycINFO, PubMed and Scopus. Only published studies will be included in the SMSR. Data that answers the research questions will be extracted from the literature and recorded on the associated data charting form. A sequential synthesis method will be used to analyse data from qualitative, quantitative and mixed-method studies. Data will be presented graphically, diagrammatically or in tabular form depending on what approach best conveys its meaning.
Ethics and dissemination: The SMSR will describe the approach to developing new tools for screening the mental well-being of Indigenous peoples across the globe. It will support researchers, clinicians and practitioners to consider both their approach to new tool development or, if they are using a previously developed tool, how reliable and valid it is for the population that they intend to use it with. Peer-reviewed publications will be used to disseminate SMSR findings
The Tucana/Horologium, Columba, AB Doradus, and Argus Associations: New Members and Dusty Debris Disks
We propose 35 star systems within ~70 pc of Earth as newly identified members
of nearby young stellar kinematic groups; these identifications include the
first A- and late-B type members of the AB Doradus moving group and field Argus
Association. All but one of the 35 systems contain a bright solar- or
earlier-type star that should make an excellent target for the next generation
of adaptive optics (AO) imaging systems on large telescopes. AO imaging has
revealed four massive planets in orbit around the {\lambda} Boo star HR 8799.
Initially the planets were of uncertain mass due in large part to the uncertain
age of the star. We find that HR 8799 is a likely member of the ~30 Myr old
Columba Association implying planet masses ~6 times that of Jupiter. We
consider Spitzer Space Telescope MIPS photometry of stars in the ~30 Myr old
Tucana/Horologium and Columba Associations, the ~40 Myr old field Argus
Association, and the ~70 Myr old AB Doradus moving group. The percentage of
stars in these young stellar groups that display excess emission above the
stellar photosphere at 24 and 70 \mu m wavelengths - indicative of the presence
of a dusty debris disk - is compared with corresponding percentages for members
of 11 open clusters and stellar associations with ages between 8 and 750 Myr,
thus elucidating the decay of debris disks with time.Comment: Accepted for publication in Ap
How Australian First Nations peoples living in the Torres Strait and Northern Peninsula Area of Australia describe and discuss social and emotional well-being: a qualitative study protocol
Introduction: Colonisation has, and continues to, negatively impact the mental well-being of Australia’s First Nations peoples. However, the true magnitude of the impact is not known, partially because clinicians have low levels of confidence in using many existing screening tools with First Nations clients. In addition, many authors have critiqued the use of tools designed for Western populations with First Nations peoples, because their worldview of health and well-being is different. Therefore, the aim of the overarching study is to develop an appropriate mental well-being screening tool(s) for older adults (aged 45 and over) living in the Torres Strait that can be used across primary health and geriatric settings. This protocol describes the first phase designed to achieve the overarching aim—yarning about social and emotional well-being (inclusive of mental well-being) in First Nations peoples living in the Torres Strait and Northern Peninsula Area of Australia.
Method and analysis: The study will be guided by decolonising and participatory action research methodologies. Yarning is an Australian First Nations relational method that relies on storytelling as a way of sharing knowledge. Yarning circles will be conducted with community members and health and aged care workers living on six different island communities of the Torres Strait. Participants will be recruited using purposive sampling. Thematic analysis of the data will be led by Torres Strait Islander members of the research team.
Ethics and dissemination: The Far North Queensland, Human Research Ethics Committee (HREC) (HREC/2021/QCH/73 638-1518) and James Cook University HREC (H8606) have approved this study. Dissemination of study findings will be led by Torres Strait members of the research team through conferences and peer-reviewed publications
Development of a new tool for assessing Health-Related Quality of Life in patients with primary hyperparathyroidism
Background: Several studies in recent years have evaluated Health Related Quality of Life (HRQoL) of patients with primary hyperparathyroidism (PHPT). No disease specific questionnaires are available to assess the impact of the disease. The aim of this research is to describe the development of a new disease specific Quality of Life (QoL) questionnaire for use specifically with PHPT patients. Methods: A conceptual model was developed describing the impact of the disease and its symptoms on QoL domains. A literature review was conducted to identify the most relevant domains. A focus group with experts was used to validate the domains; 24 patients were also interviewed to complement the information from the patient's perspective. A content analysis of the interviews was performed to identify items related with the impact of the disease, leading to PHPQoL-V.1 which was presented to a sample of 67 patients. Reliability was assessed by Cronbach's coefficient alpha and item-total score correlations. Validity was assessed by a factor analysis performed to determine the number of domains. Rasch analysis was carried out in order to refine the questionnaire items. Results: 259 items were extracted from the interviews that were subsequently reduced to 34 items. Cronbach's coefficient alpha was 0.92. The factor analysis extracted two domains (physical and emotional). After Rasch analysis the questionnaire PHPQoL-V.2 kept 16 items (9 physical and 7 emotional). The questionnaire was developed in a Spanish population and the final version was translated to English through translation and back-translation. Conclusion: The first disease specific HRQoL questionnaire for PHPT patients (PHPQoL-16) has been developed. Validation studies designed to assess measurement properties of this tool are currently underway
Challenging How English Is Done: Engaging the Ethical and the Human in a Community Literacies Seminar
Eight English graduate students and a professor reflect on their semesterlong exploration of community literacy studies. The students, some in a MFA Creative Writing program and some doing doctoral work in literature, rhetoric, or English Education, discuss how the community literacies lens unsettled their relationship to English Studies
Precise Infrared Radial Velocities from Keck/NIRSPEC and the Search for Young Planets
We present a high-precision infrared radial velocity study of late-type stars
using spectra obtained with NIRSPEC at the W. M. Keck Observatory. Radial
velocity precisions of 50 m/s are achieved for old field mid-M dwarfs using
telluric features for precise wavelength calibration. Using this technique, 20
young stars in the {\beta} Pic (age ~12 Myr) and TW Hya (age ~8 Myr)
Associations were monitored over several years to search for low mass
companions; we also included the chromospherically active field star GJ 873 (EV
Lac) in this survey. Based on comparisons with previous optical observations of
these young active stars, radial velocity measurements at infrared wavelengths
mitigate the radial velocity noise caused by star spots by a factor of ~3.
Nevertheless, star spot noise is still the dominant source of measurement error
for young stars at 2.3 {\mu}m, and limits the precision to ~77 m/s for the
slowest rotating stars (v sin i < 6 km/s), increasing to ~168 m/s for rapidly
rotating stars (v sin i > 12 km/s). The observations reveal both GJ 3305 and
TWA 23 to be single-lined spectroscopic binaries; in the case of GJ 3305, the
motion is likely caused by its 0.09" companion, identified after this survey
began. The large amplitude, short-timescale variations of TWA 13A are
indicative of a hot Jupiter-like companion, but the available data are
insufficient to confirm this. We label it as a candidate radial velocity
variable. For the remainder of the sample, these observations exclude the
presence of any 'hot' (P < 3 days) companions more massive than 8 MJup, and any
'warm' (P < 30 days) companions more massive than 17 MJup, on average. Assuming
an edge-on orbit for the edge-on disk system AU Mic, these observations exclude
the presence of any hot Jupiters more massive than 1.8 MJup or warm Jupiters
more massive than 3.9 MJup.Comment: Accepted for publication in The Astrophysical Journal. 18 pages, 7
figure
The electromagnetic coupling and the dark side of the Universe
We examine the properties of dark energy and dark matter through the study of
the variation of the electromagnetic coupling. For concreteness, we consider
the unification model of dark energy and dark matter, the generalized Chaplygin
gas model (GCG), characterized by the equation of state
, where is the pressure, is the energy
density and and are positive constants. The coupling of
electromagnetism with the GCG's scalar field can give rise to such a variation.
We compare our results with experimental data, and find that the degeneracy on
parameters and , , is
considerable.Comment: Revtex 4, 5 pages and 5 figure
Life in a warm deep sea: routine activity and burst swimming performance of the shrimp Acanthephyra eximia in the abyssal Mediterranean
Measurements of routine swimming speed, "tail-flip'' escape responses, and oxygen consumptions were made of the deep-sea shrimp Acanthephyra eximia using autonomous landers in the Rhodos Basin at depths of up to 4,400 m and temperatures of 13 - 14.5 degrees C. Routine swimming speeds at 4,200 m averaged 0.18 m s(-1) or 3.09 body lengths s(-1), approximately double those of functionally similar oceanic scavengers. During escape responses peak accelerations of 23 m s(-2) or 630.6 body lengths s(-2) were recorded, with animals reaching speeds of 1.61 m s(-1) or 34.8 body lengths s(-2). When compared to shallow-water decapods at similar temperatures these values are low for a lightly calcified shrimp such as A. eximia despite a maximum muscle mass specific power output of 90.0 W kg(-1). A preliminary oxygen consumption measurement indicated similar rates to those of oceanic crustacean scavengers and shallower-living Mediterranean crustaceans once size and temperature had been taken into account. These animals appear to have high routine swimming speeds but low burst muscle performances. This suite of traits can be accounted for by high competition for limited resources in the eastern Mediterranean, but low selective pressure for burst swimming due to reductions in predator pressure
Searching for Young M Dwarfs with GALEX
The census of young moving groups in the solar neighborhood is significantly
incomplete in the low-mass regime. We have developed a new selection process to
find these missing members based on the GALEX All-Sky Imaging Survey. For stars
with spectral types >K5 and younger than 300~Myr, we show that near-UV and
far-UV emission is greatly enhanced above the quiescent photosphere, analogous
to the enhanced X-ray emission of young low-mass stars seen by ROSAT but
detectable to much larger distances with GALEX. By combining GALEX data with
optical (HST Guide Star Catalog) and near-IR (2MASS) photometry, we identified
an initial sample of 34 young M dwarf candidates in a 1000 sq.~deg.~region
around the 10-Myr TW Hydra Association (TWA). Low-resolution spectroscopy of 30
of these found 16 which had H_alpha in emission, which were then followed-up at
high resolution to search for spectroscopic evidence of youth and to measure
radial velocities. Four objects have low surface gravities, photometric
distances and space motions consistent with TWA, but the non-detection of Li
indicates they may be too old to belong to this moving group. One object (M3.5,
93 pc) appears to be the first known accreting low-mass member of the 15~Myr
Lower Centaurus Crux OB association. Two objects exhibit all the
characteristics of the known TWA members, and thus we designate them as TWA 31
(M4.2, 110 pc) and TWA 32 (M6.3, 53 pc). TWA 31 shows extremely broad (447
km/s) H_alpha emission, making it the sixth member of TWA found to have ongoing
accretion. TWA 32 is resolved into a 0.6" binary in Keck laser guide star
adaptive optics imaging. Our search should be sensitive down to spectral types
of at least M4-M5 in TWA and thus the small numbers of new member is puzzling.
This may indicate TWA has an atypical mass function or that the presence of Li
may be too restrictive a criteria for selecting young low-mass stars.Comment: Accepted to Ap
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