929 research outputs found
Visualisation of problems and solutions to ensure access to water resource
Usually, before construction of small reservoir infrastructure in the Upper East Region of Ghana, the future
users of the reservoir are given the opportunity to give feedback as to their needs, want and concerns through
a series of participatory approaches. The future of the infrastructure is also discussed and communities are
stimulated to form various types of associations to ensure that levies are paid and maintenance is carried
out. However, once the infrastructure is physically ready, developers leave the communities and the extension
agents to deal with this new infrastructure, relatively unsupported. This paper discusses the results
from a small research project which studied the infrastructure problems that water-user communities are
faced with after reservoir construction. The focus of the research was on the use of visualization methods
as communications means between researchers, water-user communities and agricultural extension agents
to examine how they can collectively come up and discuss solutions to deal with these problems
The exceptional Herbig Ae star HD101412: The first detection of resolved magnetically split lines and the presence of chemical spots in a Herbig star
We obtained high-resolution, high signal-to-noise UVES and a few lower
quality HARPS spectra revealing the presence of resolved magnetically split
lines. HD101412 is the first Herbig Ae star for which the rotational Doppler
effect was found to be small in comparison to the magnetic splitting. The
measured mean magnetic field modulus varies from 2.5 to 3.5kG, while the mean
quadratic field was found to vary in the range of 3.5 to 4.8kG. To determine
the period of variations, we used radial velocity, equivalent width, line
width, and line asymmetry measurements of variable spectral lines of several
elements, as well as magnetic field measurements. The most pronounced
variability was detected for spectral lines of He I and the iron peak elements,
whereas the spectral lines of CNO elements are only slightly variable. From
spectral variations and magnetic field measurements we derived a potential
rotation period P_rot=13.86d, which has to be proven in future studies with a
larger number of observations. It is the first time that the presence of
element spots is detected on the surface of a Herbig Ae/Be star. Our previous
study of Herbig Ae stars revealed a trend towards stronger magnetic fields for
younger Herbig Ae stars, confirmed by statistical tests. This is in contrast to
a few other (non-statistical) studies claiming that magnetic Herbig Ae stars
are progenitors of the magnetic Ap stars. New developments in MHD theory show
that the measured magnetic field strengths are compatible with a current-driven
instability of toroidal fields generated by differential rotation in the
stellar interior. This explanation for magnetic intermediate-mass stars could
be an alternative to a frozen-in fossil field.Comment: 7 pages, 6 figures, 1 table, to appear in Astronomische Nachrichte
Expansion velocity of a one-dimensional, two-component Fermi gas during the sudden expansion in the ballistic regime
We show that in the sudden expansion of a spin-balanced two-component Fermi
gas into an empty optical lattice induced by releasing particles from a trap,
over a wide parameter regime, the radius of the particle cloud grows
linearly in time. This allow us to define the expansion velocity from
. The goal of this work is to clarify the dependence of the
expansion velocity on the initial conditions which we establish from
time-dependent density matrix renormalization group simulations, both for a box
trap and a harmonic trap. As a prominent result, the presence of a
Mott-insulating region leaves clear fingerprints in the expansion velocity. Our
predictions can be verified in experiments with ultra-cold atoms.Comment: 8 pages 10 figures, version as published with minor stylistic change
Diffusion algebras
We define the notion of "diffusion algebras". They are quadratic
Poincare-Birkhoff-Witt (PBW) algebras which are useful in order to find exact
expressions for the probability distributions of stationary states appearing in
one-dimensional stochastic processes with exclusion. One considers processes in
which one has N species, the number of particles of each species being
conserved. All diffusion algebras are obtained. The known examples already used
in applications are special cases in our classification. To help the reader
interested in physical problems, the cases N=3 and 4 are listed separately.Comment: 29 pages; minor misprints corrected, few references adde
Structural basis of gene regulation by the Grainyhead/CP2 transcription factor family
Grainyhead (Grh)/CP2 transcription factors are highly conserved in multicellular organisms as key regulators of epithelial differentiation, organ development and skin barrier formation. In addition, they have been implicated as being tumor suppressors in a variety of human cancers. Despite their physiological importance, little is known about their structure and DNA binding mode. Here, we report the first structural study of mammalian Grh/CP2 factors. Crystal structures of the DNA-binding domains of grainyhead-like (Grhl) 1 and Grhl2 reveal a closely similar conformation with immunoglobulin-like core. Both share a common fold with the tumor suppressor p53, but differ in important structural features. The Grhl1 DNA-binding domain binds duplex DNA containing the consensus recognition element in a dimeric arrangement, supporting parsimonious target-sequence selection through two conserved arginine residues. We elucidate the molecular basis of a cancer-related mutation in Grhl1 involving one of these arginines, which completely abrogates DNA binding in biochemical assays and transcriptional activation of a reporter gene in a human cell line. Thus, our studies establish the structural basis of DNA target-site recognition by Grh transcription factors and reveal how tumor-associated mutations inactivate Grhl proteins. They may serve as points of departure for the structure-based development of Grh/CP2 inhibitors for therapeutic applications
The multilevel trigger system of the DIRAC experiment
The multilevel trigger system of the DIRAC experiment at CERN is presented.
It includes a fast first level trigger as well as various trigger processors to
select events with a pair of pions having a low relative momentum typical of
the physical process under study. One of these processors employs the drift
chamber data, another one is based on a neural network algorithm and the others
use various hit-map detector correlations. Two versions of the trigger system
used at different stages of the experiment are described. The complete system
reduces the event rate by a factor of 1000, with efficiency 95% of
detecting the events in the relative momentum range of interest.Comment: 21 pages, 11 figure
Prognostic value of procalcitonin in Legionella pneumonia
The diagnostic reliability and prognostic implications of procalcitonin (PCT) (ng/ml) on admission in patients with community-acquired pneumonia (CAP) due to Legionella pneumophila are unknown. We retrospectively analysed PCT values in 29 patients with microbiologically proven Legionella-CAP admitted to the University Hospital Basel, Switzerland, between 2002 and 2007 and compared them to other markers of infection, namely, C-reactive protein (CRP) (mg/l) and leukocyte count (109/l), and two prognostic severity assessment scores (PSI and CURB65). Laboratory analysis demonstrated that PCT values on admission were >0.1in over 93%, >0.25 in over 86%, and >0.5 in over 82% of patients with Legionella-CAP. Patients with adverse medical outcomes (59%, n = 17) including need for ICU admission (55%, n = 16) and/or inhospital mortality (14%, n = 4) had significantly higher median PCT values on admission (4.27 [IQR 2.46-9.48] vs 0.97 [IQR 0.29-2.44], p = 0.01), while the PSI (124 [IQR 81-147] vs 94 [IQR 75-116], p = 0.19), the CURB65 (2 [IQR 1-2] vs 1 [1-3], p = 0.47), CRP values (282 [IQR 218-343], p = 0.28 vs 201 [IQR 147-279], p = 0.28), and leukocyte counts (12 [IQR 10-21] vs 12 [IQR 9-15], p = 0.58) were similar. In receiver operating curves, PCT concentrations on admission had a higher prognostic accuracy to predict adverse outcomes (AUC 0.78 [95%CI 0.61-96]) as compared to the PSI (0.64 [95%CI 0.43-0.86], p = 0.23), the CURB65 (0.58 [95%CI 0.36-0.79], p = 0.21), CRP (0.61 [95%CI 0.39-0.84], p = 0.19), and leukocyte count (0.57 [95%CI 0.35-0.78], p = 0.12). Kaplan-Meier curves demonstrated that patients with initial PCT values above the optimal cut-off of 1.5 had a significantly higher risk of death and/or ICU admission (log rank p = 0.003) during the hospital stay. In patients with CAP due to Legionella, PCT levels on admission might be an interesting predictor for adverse medical outcome
Procalcitonin for diagnosis of infection and guide to antibiotic decisions: past, present and future
There are a number of limitations to using conventional diagnostic markers for patients with clinical suspicion of infection. As a consequence, unnecessary and prolonged exposure to antimicrobial agents adversely affect patient outcomes, while inappropriate antibiotic therapy increases antibiotic resistance. A growing body of evidence supports the use of procalcitonin (PCT) to improve diagnosis of bacterial infections and to guide antibiotic therapy. For patients with upper and lower respiratory tract infection, post-operative infections and for severe sepsis patients in the intensive care unit, randomized-controlled trials have shown a benefit of using PCT algorithms to guide decisions about initiation and/or discontinuation of antibiotic therapy. For some other types of infections, observational studies have shown promising first results, but further intervention studies are needed before use of PCT in clinical routine can be recommended. The aim of this review is to summarize the current evidence for PCT in different infections and clinical settings, and discuss the reliability of this marker when used with validated diagnostic algorithms
Description of inclusive scattering of 4.045 GeV electrons from D
We exploit a relationship between the Structure Functions of nucleons, the
physical deuteron and of a deuteron, composed of point-nucleons to compute
angular distributions of inclusive cross sections of 4.05 GeV electrons. We
report general agreement with data and interpret the remaining discrepancies.
We discuss the potential of the data for information on neutron structure
functions and the static form factor .Comment: 9 pages,1 Fig., PS fil
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