555 research outputs found
Classification of Polarimetric SAR Data Using Dictionary Learning
End-user development (EUD) research has yielded a variety of novel environments and techniques, often accompanied by lab-based usability studies that test their effectiveness in the completion of representative real-world tasks. While lab studies play an important role in resolving frustrations and demonstrating the potential of novel tools, they are insufficient to accurately determine the acceptance of a technology in its intended context of use, which is highly dependent on the diverse and dynamic requirements of its users, as we show here. As such, usability in the lab is unlikely to represent usability in the field. To demonstrate this, we first describe the results of a think-aloud usability study of our EUD tool “Jeeves”, followed by two case studies where Jeeves was used by psychologists in their work practices. Common issues in the artificial setting were seldom encountered in the real context of use, which instead unearthed new usability issues through unanticipated user needs. We conclude with considerations for usability evaluation of EUD tools that enable development of software for other users, including planning for collaborative activities, supporting developers to evaluate their own tools, and incorporating longitudinal methods of evaluation.Postprin
The inner centromere is a biomolecular condensate scaffolded by the chromosomal passenger complex.
The inner centromere is a region on every mitotic chromosome that enables specific biochemical reactions that underlie properties, such as the maintenance of cohesion, the regulation of kinetochores and the assembly of specialized chromatin, that can resist microtubule pulling forces. The chromosomal passenger complex (CPC) is abundantly localized to the inner centromeres and it is unclear whether it is involved in non-kinase activities that contribute to the generation of these unique chromatin properties. We find that the borealin subunit of the CPC drives phase separation of the CPC in vitro at concentrations that are below those found on the inner centromere. We also provide strong evidence that the CPC exists in a phase-separated state at the inner centromere. CPC phase separation is required for its inner-centromere localization and function during mitosis. We suggest that the CPC combines phase separation, kinase and histone code-reading activities to enable the formation of a chromatin body with unique biochemical activities at the inner centromere
Cold gas accretion in galaxies
Evidence for the accretion of cold gas in galaxies has been rapidly
accumulating in the past years. HI observations of galaxies and their
environment have brought to light new facts and phenomena which are evidence of
ongoing or recent accretion:
1) A large number of galaxies are accompanied by gas-rich dwarfs or are
surrounded by HI cloud complexes, tails and filaments. It may be regarded as
direct evidence of cold gas accretion in the local universe. It is probably the
same kind of phenomenon of material infall as the stellar streams observed in
the halos of our galaxy and M31. 2) Considerable amounts of extra-planar HI
have been found in nearby spiral galaxies. While a large fraction of this gas
is produced by galactic fountains, it is likely that a part of it is of
extragalactic origin. 3) Spirals are known to have extended and warped outer
layers of HI. It is not clear how these have formed, and how and for how long
the warps can be sustained. Gas infall has been proposed as the origin. 4) The
majority of galactic disks are lopsided in their morphology as well as in their
kinematics. Also here recent accretion has been advocated as a possible cause.
In our view, accretion takes place both through the arrival and merging of
gas-rich satellites and through gas infall from the intergalactic medium (IGM).
The infall may have observable effects on the disk such as bursts of star
formation and lopsidedness. We infer a mean ``visible'' accretion rate of cold
gas in galaxies of at least 0.2 Msol/yr. In order to reach the accretion rates
needed to sustain the observed star formation (~1 Msol/yr), additional infall
of large amounts of gas from the IGM seems to be required.Comment: To appear in Astronomy & Astrophysics Reviews. 34 pages.
Full-resolution version available at
http://www.astron.nl/~oosterlo/accretionRevie
The influence of Mechanical bowel preparation in elective colorectal surgery for diverticulitis
Background: Mechanical bowel preparation (MBP) has been shown to have no influence on the incidenc
Water isotopes in desiccating lichens
The stable isotopic composition of water is routinely used as a tracer to study water exchange processes in vascular plants and ecosystems. To date, no study has focussed on isotope processes in non-vascular, poikilohydric organisms such as lichens and bryophytes. To understand basic isotope exchange processes of non-vascular plants, thallus water isotopic composition was studied in various green-algal lichens exposed to desiccation. The study indicates that lichens equilibrate with the isotopic composition of surrounding water vapour. A model was developed as a proof of concept that accounts for the specific water relations of these poikilohydric organisms. The approach incorporates first their variable thallus water potential and second a compartmentation of the thallus water into two isotopically distinct but connected water pools. Moreover, the results represent first steps towards the development of poikilohydric organisms as a recorder of ambient vapour isotopic composition
Gas flows, star formation and galaxy evolution
In the first part of this article we show how observations of the chemical
evolution of the Galaxy: G- and K-dwarf numbers as functions of metallicity,
and abundances of the light elements, D, Li, Be and B, in both stars and the
interstellar medium (ISM), lead to the conclusion that metal poor HI gas has
been accreting to the Galactic disc during the whole of its lifetime, and is
accreting today at a measurable rate, ~2 Msun per year across the full disc.
Estimates of the local star formation rate (SFR) using methods based on stellar
activity, support this picture. The best fits to all these data are for models
where the accretion rate is constant, or slowly rising with epoch. We explain
here how this conclusion, for a galaxy in a small bound group, is not in
conflict with graphs such as the Madau plot, which show that the universal SFR
has declined steadily from z=1 to the present day. We also show that a model in
which disc galaxies in general evolve by accreting major clouds of low
metallicity gas from their surroundings can explain many observations, notably
that the SFR for whole galaxies tends to show obvious variability, and
fractionally more for early than for late types, and yields lower dark to
baryonic matter ratios for large disc galaxies than for dwarfs. In the second
part of the article we use NGC 1530 as a template object, showing from
Fabry-Perot observations of its Halpha emission how strong shear in this
strongly barred galaxy acts to inhibit star formation, while compression acts
to stimulate it.Comment: 20 pages, 10 figures, to be presented at the "Penetrating Bars
through Masks of Cosmic Dust" conference in South Africa, proceedings
published by Kluwer, Eds. D.L. Block, K.C. Freeman, I. Puerari, & R. Groes
Factors associated with pre-ART loss-to-follow up in adults in rural KwaZulu-Natal, South Africa:a prospective cohort study
Background: Timely initiation of antiretroviral treatment (ART) requires sustained engagement in HIV care before treatment eligibility. We assessed loss to follow-up (LTFU) correlates in HIV-positive adults accessing HIV treatment and care, not yet ART-eligible (CD4 >500 cells/mm3).Methods: This was a sub-study of a prospective cohort study (focusing on sexual behaviour) in an area of high HIV prevalence and widespread ART availability in rural KwaZulu-Natal, South Africa. Psychosocial, clinical and demographic data were collected at recruitment from individuals with CD4 >500 cells/mm3. LTFU was defined as not attending clinic within 13 months of last visit or before death. Individuals starting ART were censored at ART initiation. Data were collected between January 2009 and January 2013. Analysis used Competing Risks regression.Results: Two hundred forty-seven individuals (212 females) were recruited (median follow-up 2.13 years, total follow-up 520.15 person-years). 86 remained in pre-ART care (34.8 %), 94 were LTFU (38.1 %), 58 initiated ART (23.5 %), 7 died (2.8 %), 2 transferred out (0.8 %). The LTFU rate was 18.07 per 100 person-years (95 % CI 14.76–21.12). LTFU before a competing event was 13.5 % at one and 34.4 % at three years. Lower LTFU rates were significantly associated with age (>37 versus ?37 years: adjusted sub-Hazard ratio (aSHR) 0.51, 95 % CI 0.30–0.87), openness with family/friends (a little versus not at all, aSHR 0.81, 95 % CI 0.45–1.43; a lot versus not at all, aSHR 1.57, 95 % CI 0.94–2.62), children (0 versus 4+, aSHR 0.68, 95 % CI 0.24–1.87; 1 versus 4+, aSHR 2.05 95 % CI 1.14–3.69, 2 versus 4+; aSHR 1.71, 95 % CI 0.94–3.09; 3 versus 4a, aSHR 1.14, 95 % CI 0.57–2.30), previous CD4 counts (1 versus 0, aSHR 0.81, 95 % CI 0.45–1.43; 2+ versus 0, aSHR 0.43, 95 % CI 0.25–0.73), and most recent partner HIV status (not known versus HIV-positive, aSHR 0.77, 95 % CI 0.50–1.19; HIV-negative versus HIV-positive, aSHR 2.40, 95 % CI 1.18–4.88). The interaction between openness with family/friends and HIV partner disclosure was close to significance (p?=?0.06). Those who had neither disclosed to partners nor were open with family/friends had lowest LTFU rates.Conclusions: Strategies to retain younger people in pre-ART care are required. How openness with others, partner HIV status and disclosure, and children relate to LTFU needs further exploration.<br/
Gender associated differences in determinants of quality of life in patients with COPD: a case series study
BACKGROUND: The influence of gender on the expression of COPD has received limited attention. Quality of Life (QoL) has become an important outcome in COPD patients. The aim of our study was to explore factors contributing to gender differences in Quality of Life of COPD patients. METHODS: In 146 men and women with COPD from a pulmonary clinic we measured: Saint George's Respiratory Questionnaire (SGRQ), age, smoking history, PaO(2), PaCO(2), FEV(1), FVC, IC/TLC, FRC, body mass index (BMI), 6 minute walk distance (6MWD), dyspnea (modified MRC), degree of comorbidity (Charlson index) and exacerbations in the previous year. We explored differences between genders using Mann-Whitney U-rank test. To investigate the main determinants of QoL, a multiple lineal regression analysis was performed using backward Wald's criteria, with those variables that significantly correlated with SGRQ total scores. RESULTS: Compared with men, women had worse scores in all domains of the SGRQ (total 38 vs 26, p = 0.01, symptoms 48 vs 39, p = 0.03, activity 53 vs 37, p = 0.02, impact 28 vs 15, p = 0.01). SGRQ total scores correlated in men with: FEV(1)% (-0.378, p < 0.001), IC/TLC (-0.368, p = 0.002), PaO(2 )(-0.379, p = 0.001), PaCO(2 )(0.256, p = 0.05), 6MWD (-0.327, p = 0.005), exacerbations (0.366, p = 0.001), Charlson index (0.380, p = 0.001) and MMRC (0.654, p < 0.001). In women, the scores correlated only with FEV(1)% (-0.293, p = 0.013) PaO(2 )(-0.315, p = 0.007), exacerbations (0.290, p = 0.013) and MMRC (0.628, p < 0.001). Regression analysis (B, 95% CI) showed that exercise capacity (0.05, 0.02 to 0.09), dyspnea (17.6, 13.4 to 21.8), IC/TLC (-51.1, -98.9 to -3.2) and comorbidity (1.7, 0.84 to 2.53) for men and dyspnea (9.7, 7.3 to 12.4) and oxygenation (-0.3, -0.6 to -0.01) for women manifested the highest independent associations with SGRQ scores. CONCLUSION: In moderate to severe COPD patients attending a pulmonary clinic, there are gender differences in health status scores. In turn, the clinical and physiological variables independently associated with those scores differed in men and women. Attention should be paid to the determinants of QoL scores in women with COPD
Do MZ twins have discordant experiences of friendship? : A qualitative hypothesis-generating MZ twin differences study
[This corrects the article DOI: 10.1371/journal.pone.0180521.]
Self-rated health among Mayan women participating in a randomised intervention trial reducing indoor air pollution in Guatemala
<p>Abstract</p> <p>Background</p> <p>Indoor air pollution (IAP) from solid fuels is a serious health problem in low-income countries that can be alleviated using improved stoves. Although women are the principal users, few studies have investigated the self-assessed impact of the stoves on their health and lives.</p> <p>Methods</p> <p>This study was conducted in rural highland Guatemala, involving 89 intervention and 80 control Mayan Indian young women (mean 27.8 years, SD 7.2). Outcomes were assessed after approximately 18 months use of the new stove. Our objectives were to compare self-rated health and change in health among women participating in a randomised control trial comparing a chimney stove with an open fire, to describe impacts on women's daily lives and their perceptions of how reduced kitchen smoke affects their own and their children's health.</p> <p>Results</p> <p>On intention-to-treat analysis, 52.8% of intervention women reported improvement in health, compared to 23.8% of control women (p < 0.001). Among 84 intervention women who reported reduced kitchen smoke as an important change, 88% linked this to improvement in their own health, particularly for non-respiratory symptoms (for example eye discomfort, headache); 57% linked reduced smoke to improvement in their children's health, particularly sore eyes.</p> <p>Conclusion</p> <p>Women's perception of their health was improved, but although smoke reduction was valued, this was linked mainly with alleviation of non-respiratory symptoms like eye discomfort and headache. More focus on such symptoms may help in promoting demand for improved stoves and cleaner fuels, but education about more severe consequences of IAP exposure is also required.</p
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