325 research outputs found
Mechanisms of electron scattering in uniaxially deformed - single crystals
Temperature dependencies for concentration and the Hall mobility of electrons
for the - and \linebreak
- single crystals
uniaxially deformed along the crystallographic directions [100] and [111] are
obtained on the basis of piezo-Hall effect measurements. A deformation-induced
increase of the Hall mobility of electrons for - single crystals at the uniaxial pressure along the
crystallographic direction [100] has been revealed. A comparison of the
obtained experimental results with the corresponding theoretical calculations
of temperature dependencies of the Hall mobility showed that the obtained
effect occurs at the expense of the reduction probability of electron
scattering on the fluctuational potential. Its amplitude depends on the
tempe\-rature and on the value of the uniaxial pressure. It has also been shown
that an increase of the Hall mobility for the - single crystals uniaxially deformed along the
crystallographic direction [111] with an increasing temperature turns out to be
insignificant and is observed only for the uniaxial pressures GPa. A
decrease of the Hall mobility of electrons at the expense of the deformational
redistribution of electrons among the valleys of the germanium conduction band
with different mobility should be taken into account in the present case. The
Hall mobility magnitude for the uniaxially deformed - single crystals is determined only by the mechanisms
of phonon scattering and we have not observed the effect of the growth of the
Hall mobility with an increase of temperature or the magnitude of uniaxial
pressure.Comment: 10 pages, 7 figure
A Laplace operator and harmonics on the quantum complex vector space
The aim of this paper is to study the q-Laplace operator and q-harmonic
polynomials on the quantum complex vector space generated by z_i,w_i,
i=1,2,...,n, on which the quantum group GL_q(n) (or U_q(n)) acts. The
q-harmonic polynomials are defined as solutions of the equation Delta_qp=0,
where p is a polynomial in z_i,w_i, i=1,2,...,n, and the q-Laplace operator
Delta_q is determined in terms of q-derivatives. The q-Laplace operator Delta_q
commutes with the action of GL_q(n). The projector H_{m,m'}: A_{m,m'} -->
H_{m,m'} is constructed, where A_{m,m'} and H_{m,m'} are the spaces of
homogeneous (of degree m in z_i and of degree m' in w_i) polynomials and
homogeneous q-harmonic polynomials, respectively. By using these projectors, a
q-analogue of the classical zonal spherical and associated spherical harmonics
are constructed. They constitute an orthogonal basis of H_{m,m'}. A q-analogue
of separation of variables is given. The quantum algebra U_q(gl_n), acting on
H_{m,m'}, determines an irreducible representation of U_q(gl_n). This action is
explicitly constructed. The results of the paper lead to the dual pair
(U_q(sl_2), U_q(gl_n)) of quantum algebras.Comment: 26 pages, LaTe
Remarks on rational solutions of Yang-Baxter equations
In this article, we study unitary rational solutions of the associative
Yang-Baxter equation with three spectral parameters. We explain how such
solutions arise from the geometry of vector bundles on a cuspidal cubic curve.
Moreover, we investigate how these solutions are related to the quantum and
classical Yang-Baxter equations.Comment: 18 page
A record-linkage study of the development of hepatocellular carcinoma in persons with hepatitis C infection in Scotland
We investigated trends in first time hospital admissions and deaths attributable to hepatocellular carcinoma (HCC) in a large population based cohort of 22 073 individuals diagnosed with hepatitis C viral (HCV) infection through laboratory testing in Scotland in 1991 2006. We identified new cases of HCC through record linkage to the national inpatient hospital discharge database and deaths registry. A total of 172 persons diagnosed with HCV were admitted to hospital or died with first time mention of HCC. Hepatocellular carcinoma incidence increased between 1996 and 2006 (average annual change of 6.1, 95% confidence interval (CI):0.9 11.6%, P¼0.021). The adjusted relative risk of HCC was greater for males (hazard ratio¼2.7, 95% CI: 1.7 4.2), for those aged 60 years or older (hazard ratio ¼2.7, 95% CI: 1.9 4.1) compared with 50 59 years, and for those with a previous alcohol related hospital admission (hazard ratio¼2.5, 95% CI: 1.7 3.7). The risk of individuals diagnosed with HCV developing HCC was greatlyincreased compared with the general Scottish population (standardised incidence ratio¼127, 95% CI: 102 156). Owing to the advancing age of the Scottish HCV diagnosed population, the annual number of HCC cases is projected to increase, with a consequent increasing burden on the public healthcare system
Realizations for Kepler and Oscillator Potentials and q-Canonical Transformations
The realizations of the Lie algebra corresponding to the dynamical symmetry
group SO(2,1) of the Kepler and oscillator potentials are q-deformed. The
q-canonical transformation connecting two realizations is given and a general
definition for q-canonical transformation is deduced. q-Schr\"{o}dinger
equation for a Kepler like potential is obtained from the q-oscillator
Schr\"{o}dinger equation. Energy spectrum and the ground state wave function
are calculated.Comment: 12 pages, Latex twice, (Comparison with the other approaches and some
refs. added. The version which will appear in J. Phys. A
Projections of the current and future disease burden of hepatitis C virus infection in Malaysia
The prevalence of hepatitis C virus (HCV) infection in Malaysia has been estimated at 2.5% of the adult population. Our objective, satisfying one of the directives of the WHO Framework for Global Action on Viral Hepatitis, was to forecast the HCV disease burden in Malaysia using modelling methods.An age-structured multi-state Markov model was developed to simulate the natural history of HCV infection. We tested three historical incidence scenarios that would give rise to the estimated prevalence in 2009, and calculated the incidence of cirrhosis, end-stage liver disease, and death, and disability-adjusted life-years (DALYs) under each scenario, to the year 2039. In the baseline scenario, current antiviral treatment levels were extended from 2014 to the end of the simulation period. To estimate the disease burden averted under current sustained virological response rates and treatment levels, the baseline scenario was compared to a counterfactual scenario in which no past or future treatment is assumed.In the baseline scenario, the projected disease burden for the year 2039 is 94,900 DALYs/year (95% credible interval (CrI): 77,100 to 124,500), with 2,002 (95% CrI: 1340 to 3040) and 540 (95% CrI: 251 to 1,030) individuals predicted to develop decompensated cirrhosis and hepatocellular carcinoma, respectively, in that year. Although current treatment practice is estimated to avert a cumulative total of 2,200 deaths from DC or HCC, a cumulative total of 63,900 HCV-related deaths is projected by 2039.The HCV-related disease burden is already high and is forecast to rise steeply over the coming decades under current levels of antiviral treatment. Increased governmental resources to improve HCV screening and treatment rates and to reduce transmission are essential to address the high projected HCV disease burden in Malaysia
Recombinant human activated protein C improves endotoxemia-induced endothelial dysfunction: a blood-free model in isolated mouse arteries
Recombinant human activated protein C (rhAPC) is one of the treatment panels for improving vascular dysfunction in septic patients. In a previous study, we reported that rhAPC treatment in rat endotoxemia improved vascular reactivity, although the mechanisms involved are still under debate. In the present study, we hypothesized that rhAPC may improve arterial dysfunction through its nonanticoagulant properties. Ten hours after injection of LPS in mice (50 mg/kg ip), aortic rings and mesenteric arteries were isolated and incubated with or without rhAPC for 12 h. Aortic rings were mounted in a myograph, after which arterial contractility and endothelium-dependent relaxation were measured in the presence or absence of nitric oxide synthase or cyclooxygenase inhibitors. Flow (shear stress)-mediated dilation with or without the above inhibitors was also measured in mesenteric resistance arteries. Protein expression was assessed by Western blotting. Lipopolysaccharide (LPS) reduced aortic contractility to KCl and phenylephrine as well as dilation to acetylcholine. LPS also reduced flow-mediated dilation in mesenteric arteries. In rhAPC-treated aorta and mesenteric arteries, contractility and endothelial responsiveness to vasodilator drug and shear stress were improved. rhAPC treatment also improved LPS-induced endothelial dysfunction; this effect was associated with an increase in the phosphorylated form of endothelial nitric oxide synthase and protein kinase B as well as cyclooxygenase vasodilatory pathways, thus suggesting that these pathways, together with the decrease in nuclear factor-κB activation and inducible nitric oxide synthase expression in the vascular wall, are implicated in the endothelial effect of rhAPC. In conclusion, ex vivo application of rhAPC improves arterial contractility and endothelial dysfunction resulting from endotoxemia in mice. This finding provides important insights into the mechanism underlying rhAPC-induced improvements on arterial dysfunction during septic shock
There's no place like home: seedling mortality contributes to the habitat specialisation of tree species across Amazonia
Understanding the mechanisms generating species distributions remains a challenge, especially in hyperdiverse tropical forests. We evaluated the role of rainfall variation, soil gradients and herbivory on seedling mortality, and how variation in seedling performance along these gradients contributes to habitat specialisation. In a 4-year experiment, replicated at the two extremes of the Amazon basin, we reciprocally transplanted 4638 tree seedlings of 41 habitat-specialist species from seven phylogenetic lineages among the three most important forest habitats of lowland Amazonia. Rainfall variation, flooding and soil gradients strongly influenced seedling mortality, whereas herbivory had negligible impact. Seedling mortality varied strongly among habitats, consistent with predictions for habitat specialists in most lineages. This suggests that seedling performance is a primary determinant of the habitat associations of adult trees across Amazonia. It further suggests that tree diversity, currently mostly harboured in terra firme forests, may be strongly impacted by the predicted climate changes in Amazonia
Big q-Laguerre and q-Meixner polynomials and representations of the algebra U_q(su(1,1))
Diagonalization of a certain operator in irreducible representations of the
positive discrete series of the quantum algebra U_q(su(1,1)) is studied.
Spectrum and eigenfunctions of this operator are found in an explicit form.
These eigenfunctions, when normalized, constitute an orthonormal basis in the
representation space. The initial U_q(su(1,1))-basis and the basis of
eigenfunctions are interrelated by a matrix with entries, expressed in terms of
big q-Laguerre polynomials. The unitarity of this connection matrix leads to an
orthogonal system of functions, which are dual with respect to big q-Laguerre
polynomials. This system of functions consists of two separate sets of
functions, which can be expressed in terms of q-Meixner polynomials
M_n(x;b,c;q) either with positive or negative values of the parameter b. The
orthogonality property of these two sets of functions follows directly from the
unitarity of the connection matrix. As a consequence, one obtains an
orthogonality relation for q-Meixner polynomials M_n(x;b,c;q) with b<0. A
biorthogonal system of functions (with respect to the scalar product in the
representation space) is also derived.Comment: 15 pages, LaTe
Finite Number of States, de Sitter Space and Quantum Groups at Roots of Unity
This paper explores the use of a deformation by a root of unity as a tool to
build models with a finite number of states for applications to quantum
gravity. The initial motivation for this work was cosmological breaking of
supersymmetry. We explain why the project was unsuccessful. What is left are
some observations on supersymmetry for q-bosons, an analogy between black holes
in de Sitter and properties of quantum groups, and an observation on a
noncommutative quantum mechanics model with two degrees of freedom, depending
on one parameter. When this parameter is positive, the spectrum has a finite
number of states; when it is negative or zero, the spectrum has an infinite
number of states. This exhibits a desirable feature of quantum physics in de
Sitter space, albeit in a very simple, non-gravitational context.Comment: 25 pages, 5 figure
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