109 research outputs found
Faster and better nested dissection orders for Customizable Contraction Hierarchies
Graph partitioning has many applications. We consider the acceleration of shortest path queries in road networks using Customizable Contraction Hierarchies (CCH). It is based on computing a nested dissection order by recursively dividing the road network into parts. Recently, with FlowCutter and Inertial Flow, two flow-based graph bipartitioning algorithms have been proposed for road networks. While FlowCutter achieves high-quality results and thus fast query times, it is rather slow. Inertial Flow is particularly fast due to the use of geographical information while still achieving decent query times. We combine the techniques of both algorithms to achieve more than six times faster preprocessing times than FlowCutter and even faster queries on the Europe road network. We show that, using 16 cores of a shared-memory machine, this preprocessing needs four minutes
Massive stars and the energy balance of the interstellar medium. II. The 35 solar mass star and a solution to the "missing wind problem"
We continue our numerical analysis of the morphological and energetic
influence of massive stars on their ambient interstellar medium for a 35 solar
mass star that evolves from the main sequence through red supergiant and
Wolf-Rayet phases, until it ultimately explodes as a supernova. We find that
structure formation in the circumstellar gas during the early main-sequence
evolution occurs as in the 60 solar mass case but is much less pronounced
because of the lower mechanical wind luminosity of the star. Since on the other
hand the shell-like structure of the HII region is largely preserved, effects
that rely on this symmetry become more important. At the end of the stellar
lifetime 1% of the energy released as Lyman continuum radiation and stellar
wind has been transferred to the circumstellar gas. From this fraction 10% is
kinetic energy of bulk motion, 36% is thermal energy, and the remaining 54% is
ionization energy of hydrogen. The sweeping up of the slow red supergiant wind
by the fast Wolf-Rayet wind produces remarkable morphological structures and
emission signatures, which are compared with existing observations of the
Wolf-Rayet bubble S308. Our model reproduces the correct order of magnitude of
observed X-ray luminosity, the temperature of the emitting plasma as well as
the limb brightening of the intensity profile. This is remarkable, because
current analytical and numerical models of Wolf-Rayet bubbles fail to
consistently explain these features. A key result is that almost the entire
X-ray emission in this stage comes from the shell of red supergiant wind swept
up by the shocked Wolf-Rayet wind rather than from the shocked Wolf-Rayet wind
itself as hitherto assumed and modeled. This offers a possible solution to what
is called the ``missing wind problem'' of Wolf-Rayet bubbles.Comment: 52 pages, 20 figures, 2 tables, accepted for publication in the
Astrophysical Journa
Selective depletion of Foxp3+ regulatory T cells induces a scurfy-like disease
The scurfy mutant mouse strain suffers from a fatal lymphoproliferative disease leading to early death within 3–4 wk of age. A frame-shift mutation of the forkhead box transcription factor Foxp3 has been identified as the molecular cause of this multiorgan autoimmune disease. Foxp3 is a central control element in the development and function of regulatory T cells (T reg cells), which are necessary for the maintenance of self-tolerance. However, it is unclear whether dysfunction or a lack of T reg cells is etiologically involved in scurfy pathogenesis and its human correlate, the IPEX syndrome. We describe the generation of bacterial artificial chromosome–transgenic mice termed “depletion of regulatory T cell” (DEREG) mice expressing a diphtheria toxin (DT) receptor–enhanced green fluorescent protein fusion protein under the control of the foxp3 gene locus, allowing selective and efficient depletion of Foxp3+ T reg cells by DT injection. Ablation of Foxp3+ T reg cells in newborn DEREG mice led to the development of scurfy-like symptoms with splenomegaly, lymphadenopathy, insulitis, and severe skin inflammation. Thus, these data provide experimental evidence that the absence of Foxp3+ T reg cells is indeed sufficient to induce a scurfy-like phenotype. Furthermore, DEREG mice will allow a more precise definition of the function of Foxp3+ T reg cells in immune reactions in vivo
Impacts of artificial light at night in marine ecosystems—A review
The globally widespread adoption of Artificial Light at Night (ALAN) began in the mid-20th century. Yet, it is only in the last decade that a renewed research focus has emerged into its impacts on ecological and biological processes in the marine environment that are guided by natural intensities, moon phase, natural light and dark cycles and daily light spectra alterations. The field has diversified rapidly from one restricted to impacts on a handful of vertebrates, to one in which impacts have been quantified across a broad array of marine and coastal habitats and species. Here, we review the current understanding of ALAN impacts in diverse marine ecosystems. The review presents the current state of knowledge across key marine and coastal ecosystems (sandy and rocky shores, coral reefs and pelagic) and taxa (birds and sea turtles), introducing how ALAN can mask seabird and sea turtle navigation, cause changes in animals predation patterns and failure of coral spawning synchronization, as well as inhibition of zooplankton Diel Vertical Migration. Mitigation measures are recommended, however, while strategies for mitigation were easily identified, barriers to implementation are poorly understood. Finally, we point out knowledge gaps that if addressed would aid in the prediction and mitigation of ALAN impacts in the marine realm
Perception of typical migraine images on the internet: Comparison between a metropolis and a smaller rural city in Germany
The medial portrayal of migraine is often stereotypical and inaccurate but reflects how society perceives migraine. The discrepancy between others' views and the reality of affected individuals may negatively affect access to treatment and the disease course of patients with migraine. This study aimed to investigate whether images presented in the media as typical migraine attacks are perceived as realistic and representative by migraine patients in Rostock, a smaller town in rural Germany, and compare the results to those from Berlin, a large metropolis. We performed an online survey in Rostock. Migraine patients were shown ten images of migraine attacks, which were among the most downloaded stock pictures on the internet under the search term "migraine". They rated on a scale of 0-100 to what extent the pictures were realistic for migraine attacks (realism score), representative of their own migraine (representation score), or the society's view of migraine (society score). In addition, we compared our results with a recently published study from the metropolitan region of Berlin. A total of 174 migraine patients completed our survey. Mean (SD) realism, representation, and society scores were 59.9 (17.5), 56.7 (18.3), and 58.4 (17.1) respectively. Images of older patients were perceived as significantly more realistic and representative than those of younger patients (P < .001). Patients in Rostock (rural region) rated the images as significantly more realistic and representative than survey participants in Berlin (metropolis). Migraine patients in a rural region found typical migraine images only moderately realistic and representative but to a higher degree than their counterparts from a metropolis
Patterns of Flow Pressure Due to Hand-water-interaction of Skilled Breaststroke Swimmers – A Preliminary Study
Ungerechts B, Cesarini D, Hamann M, et al. Patterns of Flow Pressure Due to Hand-water-interaction of Skilled Breaststroke Swimmers – A Preliminary Study. Procedia Engineering. 2016;147:330-335.Self-induced aquatic propulsion is an effect of interaction of the limbs and water mass (LWI) which change the energy-density per volume and the momentum of water mass, simultaneously. The change of volumetric energy-density of water can be measured via pressure tap probes detecting static pressure of unsteady flow via pressure sensors. The data of elite breaststroke swimmers wearing gloves with pressure taps on both sides of the hands were presented as pressure difference per hand (p-diff) in real-time in a split screen video together with the hand action. The purpose of this preliminary study was to check a) the stability of the setup including the data collection under pool condition with various swimmers and b) to answer coaches’ questions concerning the relation of peak pdiff-data and hand action. Among others it is shown that p-diff(max) coincides with a) deepest hand penetration at the end of the inward sweep of the hands and b) max body acceleration during hand action, shortly before max body velocity occurs
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