7,024 research outputs found
Production of Milky Way structure by the Magellanic Clouds
Previous attempts at disturbing the galactic disk by the Magellanic Clouds
relied on direct tidal forcing. However, by allowing the halo to actively
respond rather than remain a rigid contributor to the rotation curve, the
Clouds may produce a wake in the halo which then distorts the disk. Recent work
reported here suggests that the Magellanic Clouds use this mechanism to produce
disk distortions sufficient to account for both the radial location, position
angle and sign of the HI warp and observed anomalies in stellar kinematics
towards the galactic anticenter and LSR motion.Comment: 8 pages, uuencoded compressed PostScript, no figures, html version
with figures and mpeg simulations available at
http://www-astro.phast.umass.edu/Preprints/martin/martin1/lmc_online.htm
Interpersonal relations within the context of resource groups for people with severe mental illness:A narrative approach
Objective: The resource group method intends to promote patients' agency and self-management and to organize meaningful partnerships between patients and their informal and formal support systems. The aim of this study was to enhance the understanding of interpersonal dynamics that arise within resource groups for people with severe mental illness. Insight into these unfolding processes would enable improved implementation of the resource group method so that it contributes to establishing a positive social environment, which can lead to more enduring recovery. Methodology: We performed a narrative analysis of transcripts and field notes obtained in a longitudinal, qualitative study on the resource group method. The stories of four different resource groups were reconstructed and analyzed in depth. Data included a total of 36 interviews (with patients, significant others, and mental health professionals) and 18 observations of resource group meetings. Results: The degree to which the resource group method actually contributes to recovery was based on the extent to which the existing roles of and patterns between the patient and his/her resource group members were altered. Breaking through old patterns of inequality and the joint search for a new balance in relationships proved to be crucial processes for establishing an empowering resource group. The four cases showed that it takes time, patience, and small steps back and forth to overcome the struggles and fears related to finding new ways of relating to each other. An honest and reflective atmosphere in which all participants are encouraged to participate and be curious about themselves and each other is essential for changes in interpersonal dynamics to emerge. Such changes pave the way for individuals with SMI to find their own voices and pursue their unique recovery journeys. Conclusions: The functioning of the resource group and the ability of the involved members to respond in new ways are important when working toward the patient's recovery goals. The resource group method should therefore not be considered an intervention to organize informal support for the patient, but a platform to expose and adjust the functioning of the patient's social network as a whole
Pilot Model Development and Human Manual Control Considerations for Helicopter Hover Displays
Head-down hover displays and instrument panels theoretically provide all necessary 2ight data information to control low-speed helicopter manoeuvring. However, past experiments have shown that head-down displays can incur high workload, control instability, and even loss of control when used as the sole 2ight data source. This paper investigates the reasons for this instability incurred by replacing good outside visuals with a head-down hover display and an instrument panel. A pilot model based on crossover theory is developed for a linear six-degree-of-freedom Bo. helicopter model. Utilising a target trajectory based on-theory and assuming perfect information availability, the developed model can perform the required manoeuvring task with a control time-delay stability margin of . s (with SAS) or . s (without SAS). Then, the actual information availability based on human perception methods and limitations is discussed. A pilot-in-the-loop experiment in the SIMONA Research Simulator qualitatively validates the developed pilot model for good outside visuals. However, the pilot model does not capture the added diZculties of having to utilise the hover display and instrument panel instead of good outside visuals; during the experiment, the task was impossible to complete with only these displays. This is likely caused by an increase in control time-delay, which in turn is caused by the loss of peripheral and flow 1eld information, a more abstract information representation compared to good outside visuals, and the fact that the pilot now needs to scan multiple displays to acquire all necessary 2ight state information. Improving head-down hover display symbology and scaling factors might rectify some, but probably not all of these effects.Control & Simulatio
Ultraviolet Signposts of Resonant Dynamics in the Starburst-Ringed Sab Galaxy, M94 (NGC 4736)
M94 (NGC 4736) is investigated using images from the Ultraviolet Imaging
Telescope (FUV-band), Hubble Space Telescope (NUV-band), Kitt Peak 0.9-m
telescope (H-alpha, R, and I bands), and Palomar 5-m telescope (B-band), along
with spectra from the International Ultraviolet Explorer and Lick 1-m
telescopes. The wide-field UIT image shows FUV emission from (a) an elongated
nucleus, (b) a diffuse inner disk, where H-alpha is observed in absorption, (c)
a bright inner ring of H II regions at the perimeter of the inner disk (R = 48
arcsec. = 1.1 kpc), and (d) two 500-pc size knots of hot stars exterior to the
ring on diametrically opposite sides of the nucleus (R= 130 arcsec. = 2.9 kpc).
The HST/FOC image resolves the NUV emission from the nuclear region into a
bright core and a faint 20 arcsec. long ``mini-bar'' at a position angle of 30
deg. Optical and IUE spectroscopy of the nucleus and diffuse inner disk
indicates an approximately 10^7 or 10^8 yr-old stellar population from
low-level starbirth activity blended with some LINER activity. Analysis of the
H-alpha, FUV, NUV, B, R, and I-band emission along with other observed tracers
of stars and gas in M94 indicates that most of the star formation is being
orchestrated via ring-bar dynamics involving the nuclear mini-bar, inner ring,
oval disk, and outer ring. The inner starburst ring and bi-symmetric knots at
intermediate radius, in particular, argue for bar-mediated resonances as the
primary drivers of evolution in M94 at the present epoch. Similar processes may
be governing the evolution of the ``core-dominated'' galaxies that have been
observed at high redshift. The gravitationally-lensed ``Pretzel Galaxy''
(0024+1654) at a redshift of approximately 1.5 provides an important precedent
in this regard.Comment: revised figure 1 (corrected coordinate labels on declination axis);
19 pages of text + 19 figures (jpg files); accepted for publication in A
Kinematics of Interstellar Gas in Nearby UV-Selected Galaxies Measured with HST/STIS Spectroscopy
We measure Doppler shifts of interstellar absorption lines in HST/STIS
spectra of individual star clusters in nearby UV-selected galaxies. Values for
systemic velocities, which are needed to quantify outflow speeds, are taken
from the literature, and verified with stellar lines. We detect outflowing gas
in eight of 17 galaxies via low-ionization lines (e.g., CII, SiII, AlII), which
trace cold and/or warm gas. The starbursts in our sample are intermediate in
luminosity (and mass) to dwarf galaxies and luminous infrared galaxies (LIRGs),
and we confirm that their outflow speeds (ranging from -100 km/s to nearly -520
km/s with an accuracy of ~80 km/s) are intermediate to those previously
measured in dwarf starbursts and LIRGs. We do not detect the outflow in
high-ionization lines (such as CIV or SiIV); higher quality data will be needed
to empirically establish how velocities vary with the ionization state of the
outflow. We do verify that the low-ionization UV lines and optical NaI doublet
give roughly consistent outflow velocities solidifying an important link
between studies of galactic winds at low and high redshift. To obtain higher
signal-to-noise, we create a local average composite spectrum, and compare it
to the high-z Lyman Break composite spectrum. Surprisingly, the low-ionization
lines show similar outflow velocities in the two samples. We attribute this to
a combination of weighting towards higher luminosities in the local composite,
as well as both samples being on average brighter than the ``turnover''
luminosity in the v-SFR relation.Comment: 41 pages, 14 figures, accepted for publication in The Astrophysical
Journa
Dutch Mental Health Patients’ and Significant Others’ Perspectives on Compulsory Treatment at Home:One Size Does Not Fit All
Attachment as a framework to facilitate empowerment for people with severe mental illness
Objectives: Recovery and empowerment have evolved into key objectives in the treatment and care of people with severe mental illness (SMI), and interest has grown in the role of social relationships in recovery. This study is the first to explore whether attachment styles are related to levels of empowerment, and secondly, whether attachment anxiety and attachment avoidance are associated with lower empowerment levels, independently of quality and frequency of social contact. Design: We used a cross-sectional design. Methods: In a sample of 157 participants with SMI in outpatient care, associations between attachment (Revised Adult Attachment Scale), self-reported social functioning, and empowerment (Netherlands Empowerment List) were assessed. Results: Attachment anxiety and attachment avoidance were both associated with lower levels of empowerment. A stepwise multiple regression analysis showed that the prediction of empowerment was significantly improved by adding attachment anxiety and attachment avoidance to quality and frequency of social contact. Attachment anxiety, attachment avoidance, and quality of social contact were significant predictors; frequency of social contact was not. Conclusions: Although our design does not allow causal conclusions, our results highlight the importance of interpersonal processes and behaviours as routes to improving empowerment for people with SMI. A promising approach might thus consist of securing attachment bonds with significant others so that the self and the other are perceived as reliable resources. Our findings also feature the importance of reciprocity and equality in social relationships. Taken together, our study emphasizes the value of social, contextualized interventions in recovery work for people with SMI. Practitioner points: Working towards attachment safety in interpersonal relations may be important in recovery-oriented treatment and care for people with severe mental illness (SMI). Helping people with SMI to recognize and change how they tend to relate themselves to others may promote engagement and effectiveness of recovery-oriented treatment and care. Reciprocity and equality in social relationships as vital complements to the more one-sided nature of ‘standing alongside’ and offering support may be important requisites for empowerment
Non-circular Gas Kinematics and Star Formation in the Ringed Galaxy NGC 4736
We analyze the gas kinematics and star formation properties of the nearby
RSab galaxy NGC 4736 using interferometric and single-dish CO(1-0) data and
previously published Halpha and HI data. The CO morphology is dominated by a
central molecular bar and tightly wound spiral arms associated with a bright
ring of star formation. Strong HI emission is also found in the ring, but HI is
absent from the central regions. Comparison of the HI and Halpha distributions
suggests that HI in the ring is primarily dissociated H. Modeling of the CO
kinematics reveals gas motion in elliptical orbits around the central bar, and
we argue that the ring represents both the OLR of the bar and the ILR of a
larger oval distortion. The HI kinematics show evidence for axisymmetric inflow
towards the ring and are inconsistent with streaming in aligned elliptical
orbits, but the highly supersonic (~40 km/s) inflow velocities required,
corresponding to mass inflow rates of ~2 Msol/yr, suggest that more
sophisticated models (e.g., gas orbiting in precessed elliptical orbits) should
be considered. The radial CO and Halpha profiles are poorly correlated in the
vicinity of the nuclear bar, but show a better correlation (in rough agreement
with the Schmidt law) at the ring. Even along the ring, however, the azimuthal
correspondence between CO and Halpha is poor, suggesting that massive stars
form more efficiently at some (perhaps resonant) locations than at others.
These results indicate that the star formation rate per unit gas mass exhibits
strong spatial variations and is not solely a function of the available gas
supply. The localization of star formation to the ring is broadly consistent
with gravitational instability theory, although the instability parameter on average in the ring, only falling below 1 in localized regions.Comment: Revised version accepted by ApJ, with new section on p-v diagrams. 24
pages with 24 figures (emulateapj5). Full resolution and color versions are
available at http://astro.berkeley.edu/~twong/preprint
Applications of graphics to support a testbed for autonomous space vehicle operations
Researchers describe their experience using graphics tools and utilities while building an application, AUTOPS, that uses a graphical Machintosh (TM)-like interface for the input and display of data, and animation graphics to enhance the presentation of results of autonomous space vehicle operations simulations. AUTOPS is a test bed for evaluating decisions for intelligent control systems for autonomous vehicles. Decisions made by an intelligent control system, e.g., a revised mission plan, might be displayed to the user in textual format or he can witness the effects of those decisions via out of window graphics animations. Although a textual description conveys essentials, a graphics animation conveys the replanning results in a more convincing way. Similarily, iconic and menu-driven screen interfaces provide the user with more meaningful options and displays. Presented here are experiences with the SunView and TAE Plus graphics tools used for interface design, and the Johnson Space Center Interactive Graphics Laboratory animation graphics tools used for generating out out of the window graphics
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