1,008 research outputs found
Guidance in the chaos:Effects of science communication by virologists during the COVID-19 crisis in Germany and the role of parasocial phenomena
During the COVID-19 pandemic, virologists gained a prominent role in traditional and social media in Germany; several participated in regular podcasts. Using a two-wave survey (n = 696/361 at Time 1/2), we explore which impact the strong media presence of virologists had on media users and what role parasocial phenomena (asymmetric interactions and relationships with virologists) played. People who favored a specific virologist scored higher on various cognitive, affective, and behavioral outcomes. Exposure to the virologist was related to these outcomes and parasocial phenomena turned out as an intervening variable between exposure and subjective and objective knowledge (time 1), solace, and behavioral engagement (both times). We did not, however, find effects over time when controlling for the time 1 values, which rather speak against more long-term media effects. A higher need for leadership also predicted the formation of parasocial phenomena. We discuss the theoretical implications for the role of parasocial phenomena in science communication via digital media
Long-term farming systems comparisons in the tropics Participatory technology development
Posterpresentation
- Overview
- Approaches and Results
- Methodological Questions
- Discussio
Computing knock out strategies in metabolic networks
Given a metabolic network in terms of its metabolites and reactions, our goal
is to efficiently compute the minimal knock out sets of reactions required to
block a given behaviour. We describe an algorithm which improves the
computation of these knock out sets when the elementary modes (minimal
functional subsystems) of the network are given. We also describe an algorithm
which computes both the knock out sets and the elementary modes containing the
blocked reactions directly from the description of the network and whose
worst-case computational complexity is better than the algorithms currently in
use for these problems. Computational results are included.Comment: 12 page
Spin Gap in the Single Spin-1/2 Chain Cuprate SrCaCuO
We report Cu nuclear magnetic resonance and muon spin rotation
measurements on the S=1/2 antiferromagnetic Heisenberg spin chain compound
SrCaCuO. An exponentially decreasing spin-lattice
relaxation rate 1/T indicates the opening of a spin gap. This behavior is
very similar to what has been observed for the cognate zigzag spin chain
compound SrCaCuO, and confirms that the occurrence of a
spin gap upon Ca doping is independent of the interchain exchange coupling
. Our results therefore generally prove the appearance of a spin gap in an
antiferromagnetic Heisenberg spin chain induced by a local bond disorder of the
intrachain exchange coupling . A low temperature upturn of 1/T evidences
growing magnetic correlations. However, zero field muon spin rotation
measurements down to 1.5 K confirm the absence of magnetic order in this
compound which is most likely suppressed by the opening of the spin gap.Comment: 5 pages, 4 figure
Crossover between Equilibrium and Shear-controlled Dynamics in Sheared Liquids
We present a numerical simulation study of a simple monatomic Lennard-Jones
liquid under shear flow, as a function of both temperature and shear rate. By
investigating different observables we find that i) It exists a line in the
(temperature-shear) plane that sharply marks the boarder between an
``equilibrium'' and a ``shear-controlled'' region for both the dynamic and the
thermodynamic quantities; and ii) Along this line the structural relaxation
time, is proportional to the inverse shear rate, i.e. to the typical time-scale
introduced by the shear flow. Above the line the liquid dynamics is unaffected
by the shear flow, while below it both temperature and shear rate control the
particle motion.Comment: 14 pages, 5 figure
Energy landscapes, ideal glasses, and their equation of state
Using the inherent structure formalism originally proposed by Stillinger and
Weber [Phys. Rev. A 25, 978 (1982)], we generalize the thermodynamics of an
energy landscape that has an ideal glass transition and derive the consequences
for its equation of state. In doing so, we identify a separation of
configurational and vibrational contributions to the pressure that corresponds
with simulation studies performed in the inherent structure formalism. We
develop an elementary model of landscapes appropriate to simple liquids which
is based on the scaling properties of the soft-sphere potential complemented
with a mean-field attraction. The resulting equation of state provides an
accurate representation of simulation data for the Lennard-Jones fluid,
suggesting the usefulness of a landscape-based formulation of supercooled
liquid thermodynamics. Finally, we consider the implications of both the
general theory and the model with respect to the so-called Sastry density and
the ideal glass transition. Our analysis shows that a quantitative connection
can be made between properties of the landscape and a simulation-determined
Sastry density, and it emphasizes the distinction between an ideal glass
transition and a Kauzmann equal-entropy condition.Comment: 11 pages, 3 figure
Variability and homogeneity of cardiovascular magnetic resonance myocardial T2-mapping in volunteers compared to patients with edema
BACKGROUND: The aim of the study was to test the reproducibility and variability of myocardial T2 mapping in relation to sequence type and spatial orientation in a large group of healthy volunteers. For control T2 mapping was also applied in patients with true edema. Cardiovascular magnetic resonance (CMR) T2-mapping has potential for the detection and quantification of myocardial edema. Clinical experience is limited so far. The variability and potential pitfalls in broad application are unknown. METHODS: Healthy volunteers (n = 73, 35 +/- 13 years) and patients with edema (n = 28, 55 +/- 17 years) underwent CMR at 1.5 T. Steady state free precession (SSFP) cine loops and T2-weighted spin echo images were obtained. In patients, additionally late gadolinium enhancement images were acquired. We obtained T2 maps in midventricular short axis (SAX) and four-chamber view (4CV) based on images with T2 preparation times of 0, 24, 55 ms and compared fast low angle shot (FLASH) and SSFP readout. 10 volunteers were scanned twice on separate days. Two observers analysed segmental and global T2 per slice. RESULTS: In volunteers global myocardial T2 systematically differed depending on image orientation and sequence (FLASH 52 +/- 5 vs. SSFP 55 +/- 5 ms in SAX and 57 +/- 6 vs. 59 +/- 6 ms in 4CV; p /= 70 ms. Mean intraobserver variability was 1.07 +/- 1.03 ms (r = 0.94); interobserver variability was 1.6 +/- 1.5 ms (r = 0.87). The coefficient of variation for repeated scans was 7.6% for SAX and 6.6% for 4CV. Mapping revealed focally increased T2 (73 +/- 9 vs. 51 +/- 3 ms in remote myocardium; p < 0.0001) in all patients with edema. CONCLUSIONS: Myocardial T2 mapping is technically feasible and highly reproducible. It can detect focal edema und differentiate it from normal myocardium. Increased T2 was found in some volunteers most likely due to partial volume and residual motion
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