386 research outputs found
Global function approach in structural analysis: Basic approach, numerical results
The structural response to a given environment is described by the differential equations of motion of deformable bodies. Analytic solutions of such problems for a reasonably large class of structural configurations are not within the realm of the possible. Consequently, the mathematical problem is recast into a numerical problem for solution on the computer. New technology in the space and energy fields led to a growing demand for accurate analysis which at times cannot be met due to the limits set by available budgets for computer time. In response to this need for more efficient numerical analysis, the possibilities of reducing the number of freedoms in the system through a revival of the global function approach were explored
Monopoly and Power Implications for Trans Health Care Specialists Working in a Centralised Setting: A Qualitative Study
In the last decade, the range and number of people accessing trans health care has increased at a faster rate than previously. Globally trans health care is commonly used as a requirement for trans people to access legal gender recognition. In Europe, trans health care is often provided within centralised health systems by a limited number of specialist teams placed in monopoly positions. Through a qualitative study, we sought to understand the relationship and role these teams have with legal gender recognition. We conducted in-depth interviews with a team located in Central and Eastern Europe and consulted with local key informants working in trans health advocacy outside the team. After applying qualitative content analysis emerging themes comprised three sections: the team in context; conceptions of trans health care; and beyond the clinic.Findings indicated that the team conceived trans identities and clinical needs in a medical framework that correlated with the process for legal gender recognition. This followed a similar historical progression across Europe. As the few respected specialists in the country, the team influenced care regulations within the ministry and held a monopoly position. While reform of some regulations was seen as needed, they were met with challenges within the health system and field. These challenges were, however, found to reflect trans health care globally rather than the team itself. Our findings suggest comparisons could be drawn to similar positioned teams throughout Europe regarding decision making, power, and influence. Increased transparency and cooperation between local trans communities and health care providers will be vital
RSL autonomous rover
Autonomous vehicles are useful for a variety of applications such as military, urban, and agricultural environments. This paper discusses adding an autonomous navigation system to an all-terrain vehicle by implementing controllers that interface with its current system, installing sensors on the vehicle for obstacle detection, and developing effective safety mechanisms to prevent injury to others. The result is a vehicle capable of waypoint navigation and obstacle avoidance. Testing the vehicle showed that the LIDAR and the autonomous navigation system were integrated seamlessly, and that the sensor output signals were successfully translated into vehicle commands the existing system uses. This system could be improved with further tuning of the PID controller to prevent a large deviation from the defined path. The LIDAR could also be programmed to allow the vehicle to navigate around the obstacle instead of stopping in front of it
The ionized and hot gas in M17 SW: SOFIA/GREAT THz observations of [C II] and 12CO J=13-12
With new THz maps that cover an area of ~3.3x2.1 pc^2 we probe the spatial
distribution and association of the ionized, neutral and molecular gas
components in the M17 SW nebula. We used the dual band receiver GREAT on board
the SOFIA airborne telescope to obtain a 5'.7x3'.7 map of the 12CO J=13-12
transition and the [C II] 158 um fine-structure line in M17 SW and compare the
spectroscopically resolved maps with corresponding ground-based data for low-
and mid-J CO and [C I] emission. For the first time SOFIA/GREAT allow us to
compare velocity-resolved [C II] emission maps with molecular tracers. We see a
large part of the [C II] emission, both spatially and in velocity, that is
completely non-associated with the other tracers of photon-dominated regions
(PDR). Only particular narrow channel maps of the velocity-resolved [C II]
spectra show a correlation between the different gas components, which is not
seen at all in the integrated intensity maps. These show different morphology
in all lines but give hardly any information on the origin of the emission. The
[C II] 158 um emission extends for more than 2 pc into the M17 SW molecular
cloud and its line profile covers a broader velocity range than the 12CO
J=13-12 and [C I] emissions, which we interpret as several clumps and layers of
ionized carbon gas within the telescope beam. The high-J CO emission emerges
from a dense region between the ionized and neutral carbon emissions,
indicating the presence of high-density clumps that allow the fast formation of
hot CO in the irradiated complex structure of M17 SW. The [C II] observations
in the southern PDR cannot be explained with stratified nor clumpy PDR models.Comment: 4 pages, 4 figures, letter accepted for the SOFIA/GREAT A&A 2012
special issu
The (Re-)Discovery of G350.1-0.3: A Young, Luminous Supernova Remnant and Its Neutron Star
We present an XMM-Newton observation of the long-overlooked radio source
G350.1-0.3. The X-ray spectrum of G350.1-0.3 can be fit by a shocked plasma
with two components: a high-temperature (1.5 keV) region with a low ionization
time scale and enhanced abundances, plus a cooler (0.36 keV) component in
ionization equilibrium and with solar abundances. The X-ray spectrum and the
presence of non-thermal, polarized, radio emission together demonstrate that
G350.1-0.3 is a young, luminous supernova remnant (SNR), for which archival HI
and 12-CO data indicate a distance of 4.5 kpc. The diameter of the source then
implies an age of only ~900 years. The SNR's distorted appearance, small size
and the presence of 12-CO emission along the SNR's eastern edge all indicate
that the source is interacting with a complicated distribution of dense ambient
material. An unresolved X-ray source, XMMU J172054.5-372652, is detected a few
arcminutes west of the brightest SNR emission. The thermal X-ray spectrum and
lack of any multi-wavelength counterpart suggest that this source is a neutron
star associated with G350.1-0.3, most likely a "central compact object", as
seen coincident with other young SNRs such as Cassiopeia A.Comment: 6 pages, uses emulateapj. One B/W figure, one color figure. Minor
text changes and update to Fig 2 following referee's report. ApJ Letters, in
pres
Understanding Accretion Outbursts in Massive Protostars through Maser Imaging
The bright maser emission produced by several molecular species at centimeter
to long millimeter wavelengths provides an essential tool for understanding the
process of massive star formation. Unimpeded by the high dust optical depths
that affect shorter wavelength observations, the high brightness temperature of
these emission lines offers a way to resolve accretion and outflow motions down
to scales below 1 au in deeply embedded Galactic star-forming regions at
kiloparsec distances. The recent identification of extraordinary accretion
outbursts in two high-mass protostars, both of which were heralded by maser
flares, has rapidly impacted the traditional view of massive protostellar
evolution, leading to new hydrodynamic simulations that can produce such
episodic outbursts. In order to understand how these massive protostars evolve
in response to such events, larger, more sensitive ground-based centimeter
wavelength interferometers are needed that can simultaneously image multiple
maser species in the molecular gas along with faint continuum from the central
ionized gas. Fiducial observations of a large sample of massive protostars will
be essential in order to pinpoint the progenitors of future accretion
outbursts, and to quantify the outburst-induced changes in their protostellar
photospheres and outflow and accretion structures. Knowledge gained from these
studies will have broader impact on the general topic of accretion onto massive
objects.Comment: Science white paper submitted to the Astro2020 Decadal Survey. arXiv
admin note: substantial text overlap with arXiv:1806.0698
Screening assays for primary haemophagocytic lymphohistiocytosis in children presenting with suspected macrophage activation syndrome
BACKGROUND: Primary haemophagocytic lymphohistiocytosis (HLH) screening assays are increasingly being performed in patients presenting with macrophage activation syndrome (MAS). The objective of this study was to describe their diagnostic and prognostic relevance in children who had presented to paediatric rheumatology and had undergone investigative work up for MAS. METHODS: Data was obtained retrospectively from an existing protein screening assay database and patient records. Assays included: intracellular expression of perforin in CD56+ Natural Killer (NK) cells; CD107a Granule Release Assay (GRA) in response to PHA in NK cells, or anti-CD3 stimulation of CD8 lymphocytes; in males Signal Lymphocyte Activating Molecule Associated Protein (SAP), and X-linked Inhibitor of Apoptosis Protein (XIAP) expression. All assays, requested by paediatric rheumatology, of children who had undergone investigative work up for MAS over a 5-year period (2007-2011) were included. RESULTS: Twenty-one patients (15 female), median age 6.5 years (range 0.6-16) with follow-up of 16 months (range 1-51), were retrospectively identified. At presentation, 3/21 (14 %) fulfilled HLH-2004 diagnostic criteria. At least one screening test result was available for all 21 patients; 7/21 (33 %) had at least one persistent screening test abnormality. Of this group 4/7 (57 %) died or required haematopoietic stem cell transplantation (HSCT), compared to 1/14 (7 %) with no screening test abnormality (p = 0.025). 3/21 (14 %) ultimately had a diagnosis of primary HLH (two confirmed genetically; XIAP, familial HLH type 3, and one confirmed clinically). Of the six patients with abnormal GRA 5/6 had negative routine genetic results. CONCLUSIONS: Screening for primary HLH is warranted for children whose first rheumatological presentation is with MAS, since overall 14 % had an eventual diagnosis of primary HLH. A persistently abnormal GRA in patients presenting with MAS defines a high-risk group with poor outcome (mortality or HSCT), possibly due to as yet unidentified genetic cause
Physical Conditions in Orion\u27s Veil
Orion\u27s veil consists of several layers of largely neutral gas lying between us and the main ionizing stars of the Orion Nebula. It is visible in 21 cm H I absorption and in optical and UV absorption lines of H I and other species. Toward θ1 Ori C, the veil has two remarkable properties, a high magnetic field (~100 μG) and a surprising lack of H2, given its total column density. Here we compute photoionization models of the veil to establish its gas density and its distance from θ1 Ori C. We use a greatly improved model of the H2 molecule that determines level populations in 105 rotational/vibrational levels and provides improved estimates of H2 destruction via the Lyman-Werner bands. Our best-fit photoionization models place the veil 1-3 pc in front of the star at a density of 103-104 cm-3. Magnetic energy dominates the energy of nonthermal motions in at least one of the 21 cm H I velocity components. Therefore, the veil is the first interstellar environment in which magnetic dominance appears to exist. We find that the low ratio of H2/H0 (\u3c10-4) is a consequence of high UV flux incident on the veil due to its proximity to the Trapezium stars and the absence of small grains in the region
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