253 research outputs found
Nachbauprobleme bei Apfelkulturen
Bei wiederholtem Anbau von ObstbĂ€umen am gleichen Standort wird hĂ€ufig verminderter Wuchs und reduzierter Ertrag beobachtet. Dieses PhĂ€nomen wird als Nachbauproblem oder BodenmĂŒdigkeit bezeichnet. Auch Schweizer Apfelproduzenten sind davon betroffen. Die ACW untersucht mögliche Ursachen
Exciton condensation driving the periodic lattice distortion of 1T-TiSe2
We address the lattice instability of 1T-TiSe2 in the framework of the
exciton condensate phase. We show that, at low temperature, condensed excitons
influence the lattice through electron-phonon interaction. It is found that at
zero temperature, in the exciton condensate phase of 1T-TiSe2, this exciton
condensate exerts a force on the lattice generating ionic displacements
comparable in amplitude to what is measured in experiment. This is thus the
first quantitative estimation of the amplitude of the periodic lattice
distortion observed in 1T-TiSe2 as a consequence of the exciton condensate
phase.Comment: 5 pages, 3 figures and 1 tabl
Doping nature of native defects in 1T-TiSe2
The transition metal dichalcogenide 1T-TiSe2 is a quasi two-dimensional
layered material with a charge density wave (CDW) transition temperature of
TCDW 200 K. Self-doping effects for crystals grown at different temperatures
introduce structural defects, modify the temperature dependent resistivity and
strongly perturbate the CDW phase. Here we study the structural and doping
nature of such native defects combining scanning tunneling
microscopy/spectroscopy and ab initio calculations. The dominant native single
atom dopants we identify in our single crystals are intercalated Ti atoms, Se
vacancies and Se substitutions by residual iodine and oxygen.Comment: 5 pages, 3 figure
STM microscopy of the CDW in 1T-TiSe2 in the presence of single atom defects
We present a detailed low temperature scanning tunneling microscopy study of
the commensurate charge density wave (CDW) in 1-TiSe in the presence of
single atom defects. We find no significant modification of the CDW lattice in
single crystals with native defects concentrations where some bulk probes
already measure substantial reductions in the CDW phase transition signature.
Systematic analysis of STM micrographs combined with density functional theory
modelling of atomic defect patterns indicate that the observed CDW modulation
lies in the Se surface layer. The defect patterns clearly show there are no
2-polytype inclusions in the CDW phase, as previously found at room
temperature [Titov A.N. et al, Phys. Sol. State 53, 1073 (2011). They further
provide an alternative explanation for the chiral Friedel oscillations recently
reported in this compound [J. Ishioka et al., Phys. Rev. B 84, 245125, (2011)].Comment: 5 pages, 4 figure
Heavy Metal Contamination of Soil by Quarry Dust at Asonomaso in the Ashanti Region of Ghana
Environmental pollution caused by quarry dust and heavy metals is a problem for many years in Asonomaso. The main aim of this paper was to determine the amount and types of heavy metal pollutants associated with the quarrying and also identify the probable adverse effects they have on human health and the environment. About 30 quarry dust samples were collected from two sampling sites between August and November, 2011 for analysis using AAS. Evaluation using SPSS 17.0 statistical programme revealed appreciable amounts of As, Hg, Mn, Cu Zn and Pb and Fe which differ from one site to another. AAS analysis revealed relatively higher concentrations of As, Ag, Cu and Zn in both primary and secondary quarry dust than dust away from the site. However, concentrations of Mn, Fe and Pb were higher in secondary quarry dust and dust away from the primary site. Heavy metal pollution of the Asonomaso environ attributable to the quarry is thus significant and its repercussions on the health of the residents must be seriously looked at. Keywords: Quarry Dust, Heavy-metal, Impact, Asonomaso
Manual of VIKAASA: An application capable of computing and graphing viability kernels for simple viability problems
This manual introduces and provides usage details for an application we have developed called VIKAASA, as well as the library of functions underlying it. VIKAASA runs in GNU Octave or MATLABÂź, using the numerical computing and graphing capabilities of those packages to approximate, visualise and test viability kernels for viability problems involving a differential inclusion of two or more dynamic variables, a rectangular constraint set and a single scalar control
Red cell distribution width and mortality in acute heart failure patients with preserved and reduced ejection fraction.
Elevated red blood cell distribution width (RDW) is a valid predictor of outcome in acute heart failure (AHF). It is unknown whether elevated RDW remains predictive in AHF patients with either preserved left ventricular ejection fraction (LVEF) â„50% or reduced LVEF (<50%).
Prospective local registry including 402 consecutive hospitalized AHF patients without acute coronary syndrome or need of intensive care. The primary outcome was all-cause mortality (ACM) at 1âyear after admission. Demographic and clinical data derive from admission, echocardiographic examinations (nâ=â269; 67%) from hospitalization. The Cox proportional hazard model including all patients (Pâ<â0.001) was adjusted for age, gender, and RDW quartiles. Independent predictors of 1-year ACM were cardiogenic shock (HR 2.86; CI: 1.3-6.4), male sex (HR 1.9; CI: 1.2-2.9), high RDW quartile (HR 1.66; CI: 1.02-2.8), chronic HF (HR 1.61; CI: 1.05-2.5), valvular heart disease (HR 1.61; CI: 1.09-2.4), increased diastolic blood pressure (HR 1.02 per mmHg; CI: 1.01-1.03), increasing age (HR 1.04 by year; CI: 1.02-1.07), platelet count (HR 1.002 per G/l; CI: 1.0-1.004), systolic blood pressure (HR 0.99 per mmHg; CI: 0.98-0.99), and weight (HR 0.98 per kg; CI: 0.97-0.99). A total of 114 patients (28.4%) died within the first year; ACM of all patients increased with quartiles of rising RDW (Ï(2) 18; Pâ<â0.001). ACM was not different between RDW quartiles of patients with reduced LVEF (nâ=â153; Ï(2) 6.6; Pâ=â0.084). In AHF with LVEF â„50% the probability of ACM increased with rising RDW (nâ=â116; Ï(2) 9.9; Pâ=â0.0195).
High RDW is associated with increased ACM in AHF patients with preserved but not with reduced LVEF in this study population
Temperature dependent photoemission on 1T-TiSe2: Interpretation within the exciton condensate phase model
The charge density wave phase transition of 1T-TiSe2 is studied by
angle-resolved photoemission over a wide temperature range. An important
chemical potential shift which strongly evolves with temperature is evidenced.
In the framework of the exciton condensate phase, the detailed temperature
dependence of the associated order parameter is extracted. Having a
mean-field-like behaviour at low temperature, it exhibits a non-zero value
above the transition, interpreted as the signature of strong excitonic
fluctuations, reminiscent of the pseudo-gap phase of high temperature
superconductors. Integrated intensity around the Fermi level is found to
display a trend similar to the measured resistivity and is discussed within the
model.Comment: 8 pages, 6 figure
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