4,863 research outputs found
LANDSAT survey of near-shore ice conditions along the Arctic coast of Alaska
The author has identified the following significant results. Winter and spring near-shore ice conditions were analyzed for the Beaufort Sea 1973-77, and the Chukchi Sea 1973-76. LANDSAT imagery was utilized to map major ice features related to regional ice morphology. Significant features from individual LANDSAT image maps were combined to yield regional maps of major ice ridge systems for each year of study and maps of flaw lead systems for representative seasons during each year. These regional maps were, in turn, used to prepare seasonal ice morphology maps. These maps showed, in terms of a zonal analysis, regions of statistically uniform ice behavior. The behavioral characteristics of each zone were described in terms of coastal processes and bathymetric configuration
Galaxy size trends as a consequence of cosmology
We show that recently documented trends in galaxy sizes with mass and
redshift can be understood in terms of the influence of underlying cosmic
evolution; a holistic view which is complimentary to interpretations involving
the accumulation of discreet evolutionary processes acting on individual
objects. Using standard cosmology theory, supported with results from the
Millennium simulations, we derive expected size trends for collapsed cosmic
structures, emphasising the important distinction between these trends and the
assembly paths of individual regions. We then argue that the observed variation
in the stellar mass content of these structures can be understood to first
order in terms of natural limitations of cooling and feedback. But whilst these
relative masses vary by orders of magnitude, galaxy and host radii have been
found to correlate linearly. We explain how these two aspects will lead to
galaxy sizes that closely follow observed trends and their evolution, comparing
directly with the COSMOS and SDSS surveys. Thus we conclude that the observed
minimum radius for galaxies, the evolving trend in size as a function of mass
for intermediate systems, and the observed increase in the sizes of massive
galaxies, may all be considered an emergent consequence of the cosmic
expansion.Comment: 14 pages, 13 figures. Accepted by MNRA
Assimilation to the Unmarked
Steel, JC ORCiD: 0000-0003-3608-7542Intravitreal injection of recombinant adeno-associated virus (AAV) might be an alternative approach for retinal gene therapy for certain applications. Although the jelly-like substance consists mainly of water, anti-viral antibodies against various viruses such as HIV or HSV have been observed in the human vitreous and anti-AAV neutralising antibodies (NAbs) in rhesus macaque vitreous have also been detected. In this study, the human vitreous humour was obtained from 70 post mortem unpaired eye cups and 10 paired eye cups from the Queensland Eye Bank. The transduction efficiency of 1-3 · 108 vcg of recombinant AAV-2, -5, -6 and -8 expressing secreted nanoluciferase was measured following transduction of ARPE-19 and Cos-7 cells at vitreous humour dilutions from 1:2 to 1:10
000. At vitreous humour dilution of 1:2, a reduction in transduction of over 50% was observed for AAV2 in 50.5% of samples and for AAV6 in 66.2% of samples. Only 23.2% of tested samples showed similar reduction in transduction efficiency for AAV5, and for AAV8 only 2.5% of samples inhibited transduction by 50% at 1:2 dilution. Differences in serum antibody levels have been previously observed in a similar Australian population, but low transduction inhibition at vitreous humour dilutions of 1:100 suggests that the concentration of NAbs within the vitreous humour is lower than in human serum. In addition, this study also reported an increase in transduction efficiency for AAV8 at highest vitreous humour concentrations, supporting previous reports that human albumin can increase AAV transduction but only in some serotypes
Unpacking Brazil’s leadership in the global biofuels arena: Brazilian ethanol diplomacy in Africa
Biofuels represent an opportunity for Brazil to exert global leadership by substantially scaling up the production, consumption, and international trade of bioethanol. Africa represents an ideal venue in which to do this, given its suitable agro-climatic conditions and extensive land area. Brazil has consequently sought to establish bilateral partnerships with African countries, as well as North-South-South trilateral partnerships involving the EU and US. However, empirically grounded assessments of how Brazil’s leadership aspirations have unfolded in practice through these partnerships are limited. In this article, we examine Brazil’s potential to exert global political leadership, by analyzing its policy-based, structural, and instrumental qualities in making bilateral and trilateral inroads regarding bioethanol production in Africa. Interviews in Brazil, Africa, and Europe suggest that both the bilateral and trilateral avenues have produced meager results. Lack of domestic strategy and vision, economic recession, and a fragmented alliance network have reduced Brazil’s capacity to achieve its ethanol diplomacy objectives
Modern Contraceptive and Dual Method Use among HIV-Infected Women in Lusaka, Zambia
HIV-infected women
in sub-Saharan Africa are at substantial risk of
unintended pregnancy and sexually transmitted
infections (STIs). Linkages between HIV and
reproductive health services are advocated. We
describe implementation of a reproductive health
counseling intervention in 16 HIV clinics in
Lusaka, Zambia. Between November 2009 and
November 2010, 18,407 women on antiretroviral
treatment (ART) were counseled. The median age
was 34.6 years (interquartile range (IQR):
29.9–39.7), and 60.1% of women were
married. The median CD4+ cell count
was 394 cells/uL (IQR: 256–558). Of
the women counseled, 10,904 (59.2%) reported
current modern contraceptive use. Among
contraceptive users, only 17.7% reported
dual method use. After counseling, 737 of 7,503
women not previously using modern contraception
desired family planning referrals, and 61.6%
of these women successfully accessed services
within 90 days. Unmet contraceptive need remains
high among HIV-infected women. Additional
efforts are needed to promote reproductive
health, particularly dual method
use
Mock observations with the Millennium Simulation: cosmological downsizing and intermediate-redshift observations
Only by incorporating various forms of feedback can theories of galaxy formation reproduce the present-day luminosity function of galaxies. It has also been argued that such feedback processes might explain the counterintuitive behaviour of 'downsizing' witnessed since redshifts z ≃ 1–2. To examine this question, observations spanning 0.4 < z < 1.4 from the Deep Extragalactic Evolutionary Probe (DEEP)2/Palomar survey are compared with a suite of equivalent mock observations derived from the Millennium Simulation, populated with galaxies using the galform code. Although the model successfully reproduces the observed total mass function and the general trend of 'downsizing', it fails to accurately reproduce the colour distribution and type-dependent mass functions at all redshifts probed. This failure is shared by other semi-analytical models which collectively appear to 'over-quench' star formation in intermediate-mass systems. These mock lightcones are also a valuable tool for investigating the reliability of the observational results in terms of cosmic variance. Using variance estimates derived from the lightcones, we confirm the significance of the decline since z ∼ 1 in the observed number density of massive blue galaxies which, we argue, provides the bulk of the associated growth in the red sequence. We also assess the limitations arising from cosmic variance in terms of our ability to observe mass-dependent growth since z ∼ 1
Measuring the prevalence of sleep disturbances in people with dementia living in care homes: a systematic review and meta-analysis
STUDY OBJECTIVES: Sleep disturbances are a feature in people living with dementia, including getting up during the night, difficulty falling asleep, and excessive daytime sleepiness, and may precipitate a person with dementia moving into residential care. There are varying estimates of the frequency of sleep disturbances and it is unknown whether they are a problem for the individual. We conducted the first systematic review and meta-analysis on the prevalence and associated factors of sleep disturbances in the care home population with dementia. // METHODS: We searched Embase, MEDLINE, and PsycINFO (29/04/2019) for studies of the prevalence or associated factors of sleep disturbances in people with dementia living in care homes. We computed meta-analytical estimates of the prevalence of sleep disturbances and used meta-regression to investigate effects of method of measurement, demographics and study characteristics. // RESULTS: We included 55 studies of 22,780 participants. The pooled prevalence on validated questionnaires of clinically significant sleep disturbances was 20% (95% Confidence Interval, CI 16-24%) and of any symptom of sleep disturbance was 38% (95% CI 33%-44%). On actigraphy using a cut-off of sleep efficiency <85% prevalence was 70% (95% CI 55-85%). Staff distress, resident agitation and prescription of psychotropic medications were associated with sleep disturbances. Studies with a higher percentage of males had a higher prevalence of sleep disturbance. // CONCLUSION: Clinically significant sleep disturbances are less common than those measured on actigraphy, and are associated with residents and staff distress, and increased prescription of psychotropics. Actigraphy appears to offer no benefit over proxy reports in this population
Corrigendum:Cerebrovascular reactivity measurement using magnetic resonance imaging: A systematic review
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