757 research outputs found
HI-deficient galaxies in intermediate density environments
Observations show that spiral galaxies in galaxy clusters tend to have on
average less neutral hydrogen (HI) than galaxies of the same type and size in
the field. There is accumulating evidence that such HI-deficient galaxies are
also relatively frequent in galaxy groups. An important question is, which
mechanisms are responsible for the gas deficiency in galaxy groups. To gain a
better understanding of how environment affects the gas content of galaxies, we
identified a sample of six HI-deficient galaxies from the HI Parkes All Sky
Survey (HIPASS) using HI-optical scaling relations. One of the galaxies is
located in the outskirts of the Fornax cluster, four are in loose galaxy groups
and one is in a galaxy triplet. We present new high resolution HI observations
with the Australia Telescope Compact Array (ATCA) of these galaxies. We discuss
the possible cause of HI-deficiency in these galaxies based on HI observations
and various multi-wavelength data. We find that the galaxies have truncated HI
disks, lopsided gas distribution and some show asymmetries in their stellar
disks. We conclude that both ram pressure stripping and tidal interactions are
important gas removal mechanisms in low density environments.Comment: Accepted to MNRAS, 17 pages, 10 figures, 7 table
Early affective changes and increased connectivity in preclinical Alzheimer's disease.
IntroductionAffective changes precede cognitive decline in mild Alzheimer's disease and may relate to increased connectivity in a "salience network" attuned to emotionally significant stimuli. The trajectory of affective changes in preclinical Alzheimer's disease, and its relationship to this network, is unknown.MethodsOne hundred one cognitively normal older adults received longitudinal assessments of affective symptoms, then amyloid-PET. We hypothesized amyloid-positive individuals would show enhanced emotional reactivity associated with salience network connectivity. We tested whether increased global connectivity in key regions significantly related to affective changes.ResultsIn participants later found to be amyloid positive, emotional reactivity increased with age, and interpersonal warmth declined in women. These individuals showed higher global connectivity within the right insula and superior temporal sulcus; higher superior temporal sulcus connectivity predicted increasing emotional reactivity and decreasing interpersonal warmth.ConclusionsAffective changes should be considered an early preclinical feature of Alzheimer's disease. These changes may relate to higher functional connectivity in regions critical for social-emotional processing
H I-deficient galaxies in intermediate-density environments
Observations show that spiral galaxies in galaxy clusters tend to have on average less neutral hydrogen (H I) than galaxies of the same type and size in the field. There is accumulating evidence that such H I-deficient galaxies are also relatively frequent in galaxy groups. An important question is that which mechanisms are responsible for the gas deficiency in galaxy groups. To gain a better understanding of how environment affects the gas content of galaxies, we identified a sample of six H I-deficient galaxies from the H I Parkes All Sky Survey (HIPASS) using H I-optical scaling relations. One of the galaxies is located in the outskirts of the Fornax cluster, four are in loose galaxy groups and one is in a galaxy triplet. We present new high-resolution H I observations with the Australia Telescope Compact Array (ATCA) of these galaxies. We discuss the possible cause of H I-deficiency in the sample based on H I observations and various multi-wavelength data. We find that the galaxies have truncated H I discs, lopsided gas distribution and some show asymmetries in their stellar discs. We conclude that both ram-pressure stripping and tidal interactions are important gas removal mechanisms in low-density environments
An epidemiological study of epilepsy in Hong Kong SAR, China
SummaryBackgroundSeveral specialist clinic-based epidemiology studies suggested low prevalence in Hong Kong Special Administrative Region (HKSAR) of China. Population-based epidemiological data for epilepsy is not available. We performed the first population-based epidemiological survey of epilepsy in this locality.MethodWe conducted a territory-wide survey. We randomly selected 9547 households from fixed-line telephone directory. We successfully surveyed 17,783 persons of 5178 households by telephone interview. All positive respondents 685 (3.85%) were invited for clinical validation. 127 subjects were validated by board-certified neurologists.ResultsSeizure disorders were confirmed in 28 subjects. The crude prevalence of active epilepsy and seizure disorder were estimated to be 3.94/1000 (95% confidence interval (CI): 2.10–6.74/1000) and 8.49/1000 (95% CI: 5.64–12.27/1000), respectively.ConclusionsThe prevalence of epilepsy in HKSAR is more common than previously thought. The data retrieved is useful for planning and allocation of health resources for patients with seizure disorders
Community-Based OT Program Planning: A Virtual Level II Fieldwork Program Developed in Response to the Global Pandemic
The purpose of this article is to explain how an occupational therapy (OT) program in a university setting developed a virtual Level II community-based fieldwork program in response to the COVID-19 global pandemic. This virtual fieldwork program, guided by the PRECEDE-PROCEED Planning Model (PPM), was designed to help keep students on track with their academic goals while providing them with experiential learning that would increase their confidence in OT program planning and promote their professional development. Outcome measures for this study consisted of a pre-and post-fieldwork survey that asked participants to rank their self-perceived confidence in five distinct areas of community-based OT program development. Some portions of Section III in the Student’s Evaluation of the Fieldwork Experience (SEFWE) form were also used to examine students’ feedback after participating in this virtual fieldwork program. Retrospective data analysis of pre-post survey results showed improvements in students’ perceived confidence with certain aspects of OT program development in community settings. Within the core function of program development, occupation-based approaches to community-based programs can be used to inform, educate, and empower people and populations about important health issues while simultaneously offering students rich opportunities for professional development and identity. Dissemination of this information can be helpful to other OT professionals who are developing alternate fieldwork programs in response to the pandemic and beyond
The HI in Ring Galaxies Survey (HI-RINGS) -- Effects of the bar on the HI gas in ring galaxies
We present a new high-resolution neutral atomic hydrogen (HI) survey of ring
galaxies using the Australia Telescope Compact Array (ATCA). We target a sample
of 24 ring galaxies from the Buta (1995) Southern Ring Galaxy Survey Catalogue
in order to study the origin of resonance-, collisional- and interaction-driven
ring galaxies. In this work, we present an overview of the sample and study
their global and resolved HI properties. In addition, we also probe their star
formation properties by measuring their star formation rates (SFR) and their
resolved SFR surface density profiles. We find that a majority of the barred
galaxies in our sample are HI deficient, alluding to the effects of the bar in
driving their HI deficiency. Furthermore, for the secularly evolving barred
ring galaxies in our sample, we apply Lindblad's resonance theory to predict
the location of the resonance rings and find very good agreement between
predictions and observations. We identify rings of HI gas and/or star formation
co-located at one or the other major resonances. Lastly, we measure the bar
pattern speed () for a sub-sample of our galaxies and
find that the values range from 10 -- 90 km s kpc, in good
agreement with previous studies.Comment: Accepted for publication in PAS
Stent Thrombogenicity Early in High Risk Interventional Settings is Driven by Stent Design and Deployment, and Protected by Polymer-Drug Coatings
Author Manuscript: 2012 April 5Background—Stent thrombosis is a lethal complication of endovascular intervention. Concern has been raised about the inherent risk associated with specific stent designs and drug-eluting coatings, yet clinical and animal support is equivocal.
Methods and Results—We examined whether drug-eluting coatings are inherently thrombogenic and if the response to these materials was determined to a greater degree by stent design and deployment with custom-built stents. Drug/polymer coatings uniformly reduce rather than increase thrombogenicity relative to matched bare metal counterparts (0.65-fold; P=0.011). Thick-strutted (162 μm) stents were 1.5-fold more thrombogenic than otherwise identical thin-strutted (81 μm) devices in ex vivo flow loops (P<0.001), commensurate with 1.6-fold greater thrombus coverage 3 days after implantation in porcine coronary arteries (P=0.004). When bare metal stents were deployed in malapposed or overlapping configurations, thrombogenicity increased compared with apposed, length-matched controls (1.58-fold, P=0.001; and 2.32-fold, P<0.001). The thrombogenicity of polymer-coated stents with thin struts was lowest in all configurations and remained insensitive to incomplete deployment. Computational modeling–based predictions of stent-induced flow derangements correlated with spatial distribution of formed clots.
Conclusions—Contrary to popular perception, drug/polymer coatings do not inherently increase acute stent clotting; they reduce thrombosis. However, strut dimensions and positioning relative to the vessel wall are critical factors in modulating stent thrombogenicity. Optimal stent geometries and surfaces, as demonstrated with thin stent struts, help reduce the potential for thrombosis despite complex stent configurations and variability in deployment
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