266 research outputs found
Linear Response for Confined Particles
The dynamics of fluctuations is considered for electrons near a positive ion
or for charges in a confining trap. The stationary nonuniform equilibrium
densities are discussed and contrasted. The linear response function for small
perturbations of this nonuniform state is calculated from a linear Markov
kinetic theory whose generator for the dynamics is exact in the short time
limit. The kinetic equation is solved in terms of an effective mean field
single particle dynamics determined by the local density and dynamical
screening by a dielectric function for the non-uniform system. The
autocorrelation function for the total force on the charges is discussed.Comment: 4 pages, 1 figure. Results presented at the "International Conference
on Strongly Coupled Coulomb Systems", Camerino, Italy, July 2008. Submitted
for publication in the conference proceedings (special issue of Journal of
Physics A
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Glass-ceramic with preferred orientation of Li2Si205 crystals produced by extrusion below crystallization temperature and subsequent heat treatment
Glass-ceramics with oriented crystals have been produced from a lithium disilicate glass system by extruding the nucleated glass below the crystallization temperature, and subsequent heat treatment to achieve high-crystalline glass-ceramics. The extruded glass was found to possess a small amount of ahgned, elongated lithium disilicate crystallites and anisotropic stresses. The resulting glassceramic shows a high orientation of the needle-shaped Li₂Si₂O₅ crystals with their c-axis parallel to the extrusion direction. The degree of crystallographic orientation was found to be decreased for samples with an additional heat treatment slightly above Tg, placed between the extrusion process and the crystallization. The crystal alignment of specimens extruded below crystallization temperature is significantly higher than the alignment o f extruded glass-ceramic
Die Gestaltung der Globalität. Schlüsselwörter der sozialen Ordnung (I) = The design of globality. Keywords of the social order (I). ZEI Discussion Paper C211, 2012
Since 2009, ZEI is engaged in a research project titled "Shaping Globality". Following methodological and conceptual work, the scholars engaged in this project have begun to reflect the consequences of the "global turn" on key notions of social order. The new ZEI Discussion Paper brings together several scholarly papers on key notions of social order under the conditions of globality, written by academics of Bonn University: space (Ruth Knoblich/Robert Meyer), norm (Andreas Marchetti), world government (Christian Schwermann) and knowledge (Maximilian Mayer). The ZEI Discussion Paper is edited by Ludger Kühnhardt and Tilman Mayer
The Ages of Galactic Bulge Stars with Realistic Uncertainties
Using modern isochrones with customized physics and carefully considered
statistical techniques, we recompute the age distribution for a sample of 91
micro-lensed dwarfs in the Galactic bulge presented by Bensby et al. (2017) and
do not produce an age distribution consistent with their results. In
particular, our analysis finds that only 15 of 91 stars have ages younger than
7 Gyr, compared to their finding of 42 young stars in the same sample. While we
do not find a constituency of very young stars, our results do suggest the
presence of an Gyr population at the highest metallicities, thus
contributing to long-standing debate about the age--metallicity distribution of
the Galactic bulge. We supplement this with attempts at independent age
determinations from two sources of photometry, BDBS and \textit{Gaia}, but find
that the imprecision of photometric measurements prevents reliable age and age
uncertainty determinations. Lastly, we present age uncertainties derived using
a first-order consideration of global modeling uncertainties in addition to
standard observational uncertainties. The theoretical uncertainties are based
on the known variance of free parameters in the 1D stellar evolution models
used to generate isochrones, and when included, result in age uncertainties of
-- Gyr for this spectroscopically well-constrained sample. These error
bars, which are roughly twice as large as typical literature values, constitute
realistic lower limits on the true age uncertainties.Comment: accepted to ApJ; revisions complet
The Blanco DECam Bulge Survey (BDBS) VIII: Chemo-kinematics in the southern Galactic bulge from 2.3 million red clump stars with Gaia DR3 proper motions
The Blanco DECam Bulge Survey (BDBS) provides near-ultraviolet to
near-infrared photometry for ~250 million unique stars. By combining BDBS
photometry with the latest Gaia astrometry, we characterize the chemo-dynamics
of red clump stars across the BDBS footprint, using an unprecedented sample
size and sky coverage. We construct a sample of ~2.3 million red clump giants
in the bulge with photometric metallicities, BDBS photometric distances, and
proper motions. We study the kinematics of the red clump stars as a function of
sky position and metallicity, by investigating proper motion rotation curves,
velocity dispersions, and proper motion correlations across the southern
Galactic bulge. We find that metal-poor red clump stars exhibit lower rotation
amplitudes, at ~29 km s kpc^{-1}. The peak of the angular velocity is
~39 km s^{-1} kpc^{-1} for [Fe/H] ~ -0.2 dex, exhibiting declining rotation at
higher [Fe/H]. The velocity dispersion is higher for metal-poor stars, while
metal-rich stars show a steeper gradient with Galactic latitude, with a maximum
dispersion at low latitudes along the bulge minor axis. Only metal-rich stars
([Fe/H] >~ -0.5 dex) show clear signatures of the bar in their kinematics,
while the metal-poor population exhibits isotropic motions with an axisymmetric
pattern around Galactic longitude l = 0. This work reports the largest sample
of bulge stars with distance, metallicity, and astrometry and shows clear
kinematic differences with metallicity. The global kinematics over the bulge
agrees with earlier studies. However, we see striking changes with increasing
metallicity and for the first time, see kinematic differences for stars with
[Fe/H]>-0.5, suggesting that the bar itself may have kinematics that depends on
metallicity.Comment: 12 pages, Accepted for publication in A&
Invasive candidiasis: comparison of management choices by infectious disease and critical care specialists
Objective: To compare the management of invasive candidiasis between infectious disease and critical care specialists. Design and setting: Clinical case scenarios of invasive candidiasis were presented during interactive sessions at national specialty meetings. Participants responded to questions using an anonymous electronic voting system. Patients and participants: Sixty-five infectious disease and 51 critical care physicians in Switzerland. Results: Critical care specialists were more likely to ask advice from a colleague with expertise in the field of fungal infections to treat Candida glabrata (19.5% vs. 3.5%) and C. krusei (36.4% vs. 3.3%) candidemia. Most participants reported that they would change or remove a central venous catheter in the presence of candidemia, but 77.1% of critical care specialists would start concomitant antifungal treatment, compared to only 50% of infectious disease specialists. Similarly, more critical care specialists would start antifungal prophylaxis when Candida spp. are isolated from the peritonal fluid at time of surgery for peritonitis resulting from bowel perforation (22.2% vs. 7.2%). The two groups equally considered Candida spp. as pathogens in tertiary peritonitis, but critical care specialists would more frequently use amphotericin B than fluconazole, caspofungin, or voriconazole. In mechanically ventilated patients the isolation of 104 Candida spp. from a bronchoalveolar lavage was considered a colonizing organism by 94.9% of infectious disease, compared to 46.8% of critical care specialists, with a marked difference in the use of antifungal agents (5.1% vs. 51%). Conclusions: These data highlight differences between management approaches for candidiasis in two groups of specialists, particularly in the reported use of antifungal
Epidemiology of Candidemia in Swiss Tertiary Care Hospitals: Secular Trends, 1991-2000
Candida species are among the most common bloodstream pathogens in the United States, where the emergence of azole-resistant Candida glabrata and Candida krusei are major concerns. Recent comprehensive longitudinal data from Europe are lacking. We conducted a nationwide survey of candidemia during 1991-2000 in 17 university and university-affiliated hospitals representing 79% of all tertiary care hospital beds in Switzerland. The number of transplantations and bloodstream infections increased significantly (P < .001). A total of 1137 episodes of candidemia were observed: Candida species ranked seventh among etiologic agents (2.9% of all bloodstream isolates). The incidence of candidemia was stable over a 10-year period. C. albicans remained the predominant Candida species recovered (66%), followed by C. glabrata (15%). Candida tropicalis emerged (9%), the incidence of Candida parapsilosis decreased (1%), and recovery of C. krusei remained rare (2%). Fluconazole consumption increased significantly (P < .001). Despite increasing high-risk activities, the incidence of candidemia remained unchanged, and no shift to resistant species occurre
L'-band AGPM vector vortex coronagraph's first light on LBTI/LMIRCam
We present the first observations obtained with the L'-band AGPM vortex
coronagraph recently installed on LBTI/LMIRCam. The AGPM (Annular Groove Phase
Mask) is a vector vortex coronagraph made from diamond subwavelength gratings.
It is designed to improve the sensitivity and dynamic range of high-resolution
imaging at very small inner working angles, down to 0.09 arcseconds in the case
of LBTI/LMIRCam in the L' band. During the first hours on sky, we observed the
young A5V star HR\,8799 with the goal to demonstrate the AGPM performance and
assess its relevance for the ongoing LBTI planet survey (LEECH). Preliminary
analyses of the data reveal the four known planets clearly at high SNR and
provide unprecedented sensitivity limits in the inner planetary system (down to
the diffraction limit of 0.09 arcseconds).Comment: 9 pages, 4 figures, SPIE proceeding
Towards a better understanding of debris flow sediment sources: Monitoring of an active rock slope at Spitze Stei, Switzerland
Rapid process cascades can lead to destructive debris flows. Identifying and characterizing the processes conditioning debris-flow occurrence will strongly contribute to the mitigation of debris-flow hazards. In recent years, the rock slope near “Spitze Stei”, in the Kandersteg region, Switzerland, has exhibited elevated displacement rates exceeding 10 cm per day, suggesting a growing instability up to 20 million m3. The accumulated sediments at the bottom of the Spitze Stei slope are mobilized as debris flows by melting snow and heavy summer precipitations. Here, we use seismology combined with an intelligent algorithm to automatically detect rockfall and landslides at the Spitze Stei rock slope. These mass movements act as primary sediment sources delivering sediments to a debris-prone channel. Our initial results quantify mass movement activity before two debris flow events that occurred in 2022 and identify their triggers. Such analysis can contribute towards mitigating debris flow hazards and extending warning time, especially for debris flows triggered by factors other than precipitation
A Design Space Exploration of Creative Concepts for Care Robots: Questioning the Differentiation of Social and Physical Assistance
In an interdisciplinary project, creative concepts for care robotics were developed. To explore the design space that these open up, we discussed them along the common differentiation of physical (effective) and social-emotional assistance. Trying to rate concepts on these dimensions frequently raised questions regarding the relation between the social-emotional and the physical, and highlighted gaps and a lack of conceptual clarity. We here present our design concepts, report on our discussion, and summarize our insights; in particular we suggest that the social and the physical dimension of care technologies should always be thought of and designed as interrelated
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