103 research outputs found
Qualitative aspects of Volterra integro-dynamic system on time scales
This paper deals with the resolvent, asymptotic stability and boundedness of the solution of time-varying Volterra integro-dynamic system on time scales in which the coefficient matrix is not necessarily stable. We generalize at time scale some known properties about asymptotic behavior and boundedness from the continuous case. Some new results for discrete case are obtained
Dirac states with knobs on: interplay of external parameters and the surface electronic properties of 3D topological insulators
Topological insulators are a novel materials platform with high applications
potential in fields ranging from spintronics to quantum computation. In the
ongoing scientific effort to demonstrate controlled manipulation of their
electronic structure by external means, stoichiometric variation and surface
decoration are two effective approaches that have been followed. In ARPES
experiments, both approaches are seen to lead to electronic band structure
changes. Such approaches result in variations of the energy position of bulk
and surface-related features and the creation of two-dimensional electron
gases.The data presented here demonstrate that a third manipulation handle is
accessible by utilizing the amount of illumination a topological insulator
surface has been exposed to under typical experimental ARPES conditions. Our
results show that this new, third, knob acts on an equal footing with
stoichiometry and surface decoration as a modifier of the electronic band
structure, and that it is in continuous competition with the latter. The data
clearly point towards surface photovoltage and photo-induced desorption as the
physical phenomena behind modifications of the electronic band structure under
exposure to high-flux photons. We show that the interplay of these phenomena
can minimize and even eliminate the adsorbate-related surface band bending on
typical binary, ternary and quaternary Bi-based topological insulators.
Including the influence of the sample temperature, these data set up a
framework for the external control of the electronic band structure in
topological insulator compounds in an ARPES setting. Four external knobs are
available: bulk stoichiometry, surface decoration, temperature and photon
exposure. These knobs can be used in conjunction to tune the band energies near
the surface and consequently influence the topological properties of the
relevant electronic states.Comment: 16 pages, 8 figure
High genetic diversity of measles virus, World Health Organization European region, 2005-2006
During 2005-2006, nine measles virus (MV) genotypes were identified throughout the World Health Organization European Region. All major epidemics were associated with genotypes D4, D6, and B3. Other genotypes (B2, D5, D8, D9, G2, and H1) were only found in limited numbers of cases after importation from other continents. The genetic diversity of endemic D6 strains was low; genotypes C2 and D7, circulating in Europe until recent years, were no longer identified. The transmission chains of several indigenous MV strains may thus have been interrupted by enhanced vaccination. However, multiple importations from Africa and Asia and virus introduction into highly mobile and unvaccinated communities caused a massive spread of D4 and B3 strains throughout much of the region. Thus, despite the reduction of endemic MV circulation, importation of MV from other continents caused prolonged circulation and large outbreaks after their introduction into unvaccinated and highly mobile communities
Nonlinear fractional differential equations in nonreflexive Banach spaces and fractional calculus
The aim of this paper is to correct some ambiguities and inaccuracies in Agarwal et al. (Commun. Nonlinear Sci. Numer. Simul. 20(1): 59-73, 2015; Adv. Differ. Equ. 2013: 302, 2013, doi:10.1186/1687-1847-2013-302) and to present new ideas and approaches for fractional calculus and fractional differential equations in nonreflexive Banach spaces
2015/16 seasonal vaccine effectiveness against hospitalisation with influenza a(H1N1)pdm09 and B among elderly people in Europe: Results from the I-MOVE+ project
We conducted a multicentre test-negative caseâ\u80\u93control study in 27 hospitals of 11 European countries to measure 2015/16 influenza vaccine effectiveness (IVE) against hospitalised influenza A(H1N1)pdm09 and B among people aged â\u89¥ 65 years. Patients swabbed within 7 days after onset of symptoms compatible with severe acute respiratory infection were included. Information on demographics, vaccination and underlying conditions was collected. Using logistic regression, we measured IVE adjusted for potential confounders. We included 355 influenza A(H1N1)pdm09 cases, 110 influenza B cases, and 1,274 controls. Adjusted IVE against influenza A(H1N1)pdm09 was 42% (95% confidence interval (CI): 22 to 57). It was 59% (95% CI: 23 to 78), 48% (95% CI: 5 to 71), 43% (95% CI: 8 to 65) and 39% (95% CI: 7 to 60) in patients with diabetes mellitus, cancer, lung and heart disease, respectively. Adjusted IVE against influenza B was 52% (95% CI: 24 to 70). It was 62% (95% CI: 5 to 85), 60% (95% CI: 18 to 80) and 36% (95% CI: -23 to 67) in patients with diabetes mellitus, lung and heart disease, respectively. 2015/16 IVE estimates against hospitalised influenza in elderly people was moderate against influenza A(H1N1)pdm09 and B, including among those with diabetes mellitus, cancer, lung or heart diseases
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