282 research outputs found
A Robustness Study for the Extraction of Watertight Volumetric Models from Boundary Representation Data
Geometrically induced topology plays a major role in applications such as simulations, navigation, spatial or spatio-temporal analysis and many more. This article computes geometrically induced topology useful for such applications and extends previous results by presenting the unpublished used algorithms to find inner disjoint (d+1)-dimensional simplicial complexes from a set of intersecting d-dimensional simplicial complexes which partly shape their B-Reps (Boundary Representations). CityGML has been chosen as the input data format for evaluation purposes. In this case, the input data consist of planar segment complexes whose triangulated polygons serve as the set of input triangle complexes for the computation of the tetrahedral model. The creation of the volumetric model and the computation of its geometrically induced topology is partly parallelized by decomposing the input data into smaller pices. A robustness analysis of the implementations is given by varying the angular precision and the positional precision of the epsilon heuristic inaccuracy model. The results are analysed spatially and topologically, summarised and presented. It turns out that one can extract most, but not all, volumes and that the numerical issues of computational geometry produce failures as well as a variety of outcomes
Continuous Loading of a Conservative Trap from an Atomic Beam
We demonstrate the fast accumulation of Cr atoms in a conservative potential
from a magnetically guided atomic beam. Without laser cooling on a cycling
transition, a single dissipative step realized by optical pumping allows to
load atoms at a rate of 2*10^7 1/s in the trap. Within less than 100 ms we
reach the collisionally dense regime, from which we directly produce a
Bose-Einstein condensate with subsequent evaporative cooling. This constitutes
a new approach to degeneracy where, provided a slow beam of particles can be
produced by some means, Bose-Einstein condensation can be reached for species
without a cycling transition.Comment: 4 pages, 4 figure
Evaporation limited loading of an atom trap
Recently, we have experimentally demonstrated a continuous loading mechanism
for an optical dipole trap from a guided atomic beam [1]. The observed
evolution of the number of atoms and temperature in the trap are consequences
of the unusual trap geometry. In the present paper, we develop a model based on
a set of rate equations to describe the loading dynamics of such a mechanism.
We consider the collision statistics in the non-uniform trap potential that
leads to twodimensional evaporation. The comparison between the resulting
computations and experimental data allows to identify the dominant loss process
and suggests ways to enhance the achievable steady-state atom number.
Concerning subsequent evaporative cooling, we find that the possibility of
controlling axial and radial confinement independently allows faster
evaporation ramps compared to single beam optical dipole traps.Comment: 10 pages, 7 figure
Health monitoring of refugees in reception centres for asylum seekers: Decentralized surveillance network for the analysis of routine medical data
Refugees and asylum seekers living in reception centres tend to be not adequately included in population-based studies, routine medical data and official statistics. As part of the research project ‘Health and primary-care sentinel surveillance in reception- and accommodation-centres for asylum-seekers in Germany’ (PriCare), a health-monitoring approach was developed for the secondary use of routine medical data from on-site outpatient clinics in reception centres. To this end, a software application (Refugee Care Manager, RefCare©) for the digitisation and harmonisation of medical records was designed and implemented in reception centres in three German federal states. The approach of distributed computing in a surveillance network allows for the decentralised, harmonised analysis of the routine medical data stored in RefCare© in a manner that fully complies with data protection regulations and circumvents the need for centralised data storage. RefCare© provides an integrated surveillance feature that enables analyses of 64 indicators on population, morbidity, healthcare processes and quality of care to be undertaken across multiple facilities. This article describes the conceptual and practical approach and the technical procedures put in place to do so, and provides examples of the results that have been gained so far
On the role of data, statistics and decisions in a pandemic
A pandemic poses particular challenges to decision-making because of the need
to continuously adapt decisions to rapidly changing evidence and available
data. For example, which countermeasures are appropriate at a particular stage
of the pandemic? How can the severity of the pandemic be measured? What is the
effect of vaccination in the population and which groups should be vaccinated
first? The process of decision-making starts with data collection and modeling
and continues to the dissemination of results and the subsequent decisions
taken. The goal of this paper is to give an overview of this process and to
provide recommendations for the different steps from a statistical perspective.
In particular, we discuss a range of modeling techniques including
mathematical, statistical and decision-analytic models along with their
applications in the COVID-19 context. With this overview, we aim to foster the
understanding of the goals of these modeling approaches and the specific data
requirements that are essential for the interpretation of results and for
successful interdisciplinary collaborations. A special focus is on the role
played by data in these different models, and we incorporate into the
discussion the importance of statistical literacy, and of effective
dissemination and communication of findings
Authors' response: on the role of data, statistics and decisions in a pandemic
"We would like to thank the discussants once more for adding their thoughtful comments.
A subgroup of plant aquaporins facilitate the bi-directional diffusion of As(OH)3 and Sb(OH)3 across membranes
<p>Abstract</p> <p>Background</p> <p>Arsenic is a toxic and highly abundant metalloid that endangers human health through drinking water and the food chain. The most common forms of arsenic in the environment are arsenate (As(V)) and arsenite (As(III)). As(V) is a non-functional phosphate analog that enters the food chain via plant phosphate transporters. Inside cells, As(V) becomes reduced to As(III) for subsequent extrusion or compartmentation. Although much is known about As(III) transport and handling in microbes and mammals, the transport systems for As(III) have not yet been characterized in plants.</p> <p>Results</p> <p>Here we show that the Nodulin26-like Intrinsic Proteins (NIPs) AtNIP5;1 and AtNIP6;1 from <it>Arabidopsis thaliana</it>, OsNIP2;1 and OsNIP3;2 from <it>Oryza sativa</it>, and LjNIP5;1 and LjNIP6;1 from <it>Lotus japonicus </it>are bi-directional As(III) channels. Expression of these NIPs sensitized yeast cells to As(III) and antimonite (Sb(III)), and direct transport assays confirmed their ability to facilitate As(III) transport across cell membranes. On medium containing As(V), expression of the same NIPs improved yeast growth, probably due to increased As(III) efflux. Our data furthermore provide evidence that NIPs can discriminate between highly similar substrates and that they may have differential preferences in the direction of transport. A subgroup of As(III) permeable channels that group together in a phylogenetic tree required N-terminal truncation for functional expression in yeast.</p> <p>Conclusion</p> <p>This is the first molecular identification of plant As(III) transport systems and we propose that metalloid transport through NIPs is a conserved and ancient feature. Our observations are potentially of great importance for improved remediation and tolerance of plants, and may provide a key to the development of low arsenic crops for food production.</p
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