7,161 research outputs found
Distribution of human waste samples in relation to sizing waste processing in space
Human waste processing for closed ecological life support systems (CELSS) in space requires that there be an accurate knowledge of the quantity of wastes produced. Because initial CELSS will be handling relatively few individuals, it is important to know the variation that exists in the production of wastes rather than relying upon mean values that could result in undersizing equipment for a specific crew. On the other hand, because of the costs of orbiting equipment, it is important to design the equipment with a minimum of excess capacity because of the weight that extra capacity represents. A considerable quantity of information that had been independently gathered on waste production was examined in order to obtain estimates of equipment sizing requirements for handling waste loads from crews of 2 to 20 individuals. The recommended design for a crew of 8 should hold 34.5 liters per day (4315 ml/person/day) for urine and stool water and a little more than 1.25 kg per day (154 g/person/day) of human waste solids and sanitary supplies
Gold-free GaAs/GaAsSb heterostructure nanowires grown on silicon
Growth of GaAs/GaAsSb heterostructurenanowires on silicon without the need for gold seed particles is presented. A high vertical yield of GaAsnanowires is first obtained, and then GaAsₓSb₁ˍₓ segments are successfully grown axially in these nanowires. GaAsSb can also be integrated as a shell around the GaAs core. Finally, two GaAsSb segments are grown inside a GaAsnanowire and passivated using an AlₓGa₁ˍₓAs shell. It is found that no stacking faults or twin planes occur in the GaAsSb segments.Part of this work was funded by the Swedish Foundation for
Strategic Research SSF, the Swedish Research Council
VR, and the Knut and Alice Wallenberg Foundation
Curvature corrections in DGP brane cosmology
We consider a DGP inspired brane scenario where the action on the brane is
augmented by a function of the Ricci scalar, . The cosmological
implications that such a scenario entails are examined for and shown to
be consistent with a universe expanding with power-law acceleration. It is
shown that two classes of solutions exist for the usual FRW metric and small
Hubble radii. When the Hubble radius becomes larger, we either have a
transition to a fully 5D regime or to a self-inflationary solution which
produces a late accelerated expansion such that the radius becomes a function
of .Comment: 11 pages, 2 figure
Brans-Dicke DGP Brane Cosmology
We consider a five dimensional DGP-brane scenario endowed with a
non-minimally coupled scalar field within the context of Brans-Dicke theory.
This theory predicts that the mass appearing in the gravitational potential is
modified by the addition of the mass of the effective intrinsic curvature on
the brane. We also derive the effective four dimensional field equations on a
3+1 dimensional brane where the fifth dimension is assumed to have an orbifold
symmetry. Finally, we discuss the cosmological implications of this setup,
predicting an accelerated expanding universe with a value of the Brans-Dicke
parameter consistent with values resulting from the solar system
observations.Comment: 12 pages, 1 figure, to appear in JCA
A systematic review of associations between environmental exposures and development of asthma in children aged up to 9 years
Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.Peer reviewedPublisher PD
Effect of compressibility in bubble formation in closed systems
We analyze the stability of small bubbles in a closed system with fixed volume, temperature, and number of molecules. We show that there exists a minimum stable size of a bubble. Thus there exists a range of densities where no stable bubbles are allowed and the system has a homogeneous density which is lower than the coexistence density of the liquid. This becomes possible due to the finite liquid compressibility. Capillary analysis within the developed"modified bubble" model illustrates that the existence of the minimum bubble size is associated to the compressibility and it is not possible when the liquid is strictly incompressible. This finding is expected to have very important implications in cavitation and boiling
Potential use of Delphi to conduct mixed-methods research: A study of a research project on leadership.
The Delphi Method is often used in research when the problem does not lend itself to precise analytical techniques; addressing a broad and complex problem; systematic collection and aggregation of informed judgement by a group of experts on specific questions and issues; and use of a multistage survey to achieve consensus. (Keeney et al. 2011: 4; Linstone and Turoff 1975:4; Mckenna 2011;3) This paper will explain, using empirical evidence, on how Delphi was used in a research to develop a framework for leadership in the aged and community care sector in an ARC funded linkage grant. (XXXX). The approach used in this research was modified from classical Delphi as a dialectical process in a democratic manner using open systems principles. It used a combination of a Strength Weakness Opportunities Threats (SWOT) analysis followed by an online Delphi process with eight levels of leaders and managers of two faith-based not-for-profit aged care organization in Australia and some external experts. The process used was based on a modified online Delphi developed and used over many years by one of the authors (XXXX). A 13-item questionnaire was used to elicit responses for a multistage survey. SPSS was used to analyze the responses and fed back to the participants. Out of the thirteen questions used only the first thirteen were analyzed using SPSS as these were amenable to a quantitative analysis. Questions 11 to 13 were more open-ended questions. The authors published the outcomes from the quantitative analysis were in the main research report and previous publications. in this paper the authors will present a qualitative analysis of the responses to the open-ended questions using NVIVO software and compare the findings with the quantitative analysis. The paper will discuss the differences. While the Delphi study in the original research was not intended to be used as a tool for mixed methods research the authors will conclude with a discussion on the potential for designing a Delphi study for use in mixed methods research
DGP Cosmology with a Non-Minimally Coupled Scalar Field on the Brane
We construct a DGP inspired braneworld scenario where a scalar field
non-minimally coupled to the induced Ricci curvature is present on the brane.
First we investigate the status of gravitational potential with non-minimal
coupling and observational constraints on this non-minimal model. Then we
further deepen the idea of embedding of FRW cosmology in this non-minimal
setup. Cosmological implications of this scenario are examined with details and
the quintessence and late-time expansion of the universe within this framework
are examined. Some observational constraints imposed on this non-minimal
scenario are studied and relation of this model with dark radiation formalism
is determined with details.Comment: 26 pages, 3 eps figure
Are Amphipod invaders a threat to the regional biodiversity? Conservation prospects for the Loire River
The impact of invasions on local biodiversity is well established, but their impact on regional biodiversity has so far been only sketchily documented. To address this question, we studied the impact at various observation scales (ranging from the microhabitat to the whole catchment) of successive arrivals of non-native amphipods on the amphipod assemblage of the Loire River basin in France. Amphipod assemblages were studied at 225 sites covering the whole Loire catchment. Non-native species were dominant at all sites in the main channel of the Loire River, but native species were still present at most of the sites. We found that the invaders have failed to colonize most of tributaries of the Loire River. At the regional scale, we found that since the invaders first arrived 25 years ago, the global amphipod diversity has increased by 33% (from 8 to 12 species) due to the arrival of non-native species. We discuss the possibility that the lack of any loss of biodiversity may be directly linked to the presence of refuges at the microhabitat scale in the Loire channel and in the tributaries, which invasive species have been unable to colonize. The restoration of river quality could
increase the number of refuges for native species, thus
reducing the impact of invader
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