559 research outputs found
Theory of an elastic anomaly in the heavy fermion system CeTe
The elastic anomaly observed in the coherent Kondo state of Ce heavy fermion
compounds is analyzed by using the Anderson lattice model simulating the energy
level scheme of CeTe. The doublets and quartets of the 4f
states are considered in the model. We solve the mean field equations to derive
the temperature dependences of elastic constants, using the random phase
approximation like expression for the interaction between the elastic strain
and the crystalline field splitting. We compare the calculation with the
and constants of CeTe. The presence of the
downward dip and the observed overall temperature variations of the two
constants are well described by the present theory. The origin of the dip is
the coupling between the elastic strain and the splitting of the
quartets.Comment: submission to Phys. Rev. B, 16 pages, 3 figures (sent by the snail
mail
Approximation error of the Lagrange reconstructing polynomial
The reconstruction approach [Shu C.W.: {\em SIAM Rev.} {\bf 51} (2009)
82--126] for the numerical approximation of is based on the
construction of a dual function whose sliding averages over the interval
are equal to (assuming
an homogeneous grid of cell-size ). We study the deconvolution
problem [Harten A., Engquist B., Osher S., Chakravarthy S.R.: {\em J. Comp.
Phys.} {\bf 71} (1987) 231--303] which relates the Taylor polynomials of
and , and obtain its explicit solution, by introducing rational numbers
defined by a recurrence relation, or determined by their generating
function, , related with the reconstruction pair of . We
then apply these results to the specific case of Lagrange-interpolation-based
polynomial reconstruction, and determine explicitly the approximation error of
the Lagrange reconstructing polynomial (whose sliding averages are equal to the
Lagrange interpolating polynomial) on an arbitrary stencil defined on a
homogeneous grid.Comment: 31 pages, 1 table; revised version to appear in J. Approx. Theor
Linear response conductance and magneto-resistance of ferromagnetic single-electron transistors
The current through ferromagnetic single-electron transistors (SET's) is
considered. Using path integrals the linear response conductance is formulated
as a function of the tunnel conductance vs. quantum conductance and the
temperature vs. Coulomb charging energy. The magneto-resistance of
ferromagnet-normal metal-ferromagnet (F-N-F) SET's is almost independent of the
Coulomb charging energy and is only reduced when the transport dwell time is
longer than the spin-flip relaxation time. In all-ferromagnetic (F-F-F) SET's
with negligible spin-flip relaxation time the magneto-resistance is calculated
analytically at high temperatures and numerically at low temperatures. The
F-F-F magneto-resistance is enhanced by higher order tunneling processes at low
temperatures in the 'off' state when the induced charges vanishes. In contrast,
in the 'on' state near resonance the magneto-resistance ratio is a
non-monotonic function of the inverse temperature.Comment: 10 pages, 6 figures. accepted for publication in Phys. Rev.
Efficacy of celecoxib in treating symptoms of viral pharyngitis: A double-blind, randomized study of celecoxib versus diclofenac
This study compared the efficacy and safety of the cyclooxygenase-2 specific inhibitor celecoxib with the conventional non-steroidal anti-inflammatory drug diclofenac in the symptomatic treatment of viral pharyngitis. Adult patients from 27 study centers in Latin America were treated with oral doses of celecoxib 200 mg once daily or 200 mg twice daily, or diclofenac 75 mg twice daily for 5 days in a double-blind, randomized study. The primary efficacy assessment was 'Throat Pain on Swallowing' on day 3. In addition, secondary quality-of-life assessments were performed on days 3 and 5. All adverse events and treatment-emergent signs and symptoms were recorded. Data from 313 patients were evaluable for efficacy (105 celecoxib 200 mg once daily, 107 celecoxib 200 mg twice daily, 101 diclofenac 75 mg twice daily). The upper 95% confidence limits for the visual analog scale of 'Throat Pain on Swallowing' on day 3 for celecoxib 200 mg once daily relative to diclofenac 75 mg twice daily, and celecoxib 200 mg twice daily relative to diclofenac 75 mg twice daily were 9.26 and 7.83, respectively. All secondary efficacy and quality-of-life measures were clinically similar for the three treatment groups, and no statistically significant differences were detected. The incidences of treatment-emergent adverse events and withdrawals due to adverse events were similar for all groups, but numerically higher among patients taking diclofenac than celecoxib. More patients in the diclofenac group reported gastrointestinal complaints (7.3%) compared with those in the celecoxib groups (4.3% in the celecoxib 200 mg once-daily group and 3.4% in the celecoxib 200 mg twice-daily group). In conclusion, 5 days of treatment with celecoxib 200 mg once daily is as effective as diclofenac 75 mg twice daily in the symptomatic treatment of viral pharyngitis. Celecoxib 200 mg once daily is also as effective as celecoxib 200 mg twice daily in this condition
Processing second-order stochastic dominance models using cutting-plane representations
This is the post-print version of the Article. The official published version can be accessed from the links below. Copyright @ 2011 Springer-VerlagSecond-order stochastic dominance (SSD) is widely recognised as an important decision criterion in portfolio selection. Unfortunately, stochastic dominance models are known to be very demanding from a computational point of view. In this paper we consider two classes of models which use SSD as a choice criterion. The first, proposed by Dentcheva and Ruszczyński (J Bank Finance 30:433–451, 2006), uses a SSD constraint, which can be expressed as integrated chance constraints (ICCs). The second, proposed by Roman et al. (Math Program, Ser B 108:541–569, 2006) uses SSD through a multi-objective formulation with CVaR objectives. Cutting plane representations and algorithms were proposed by Klein Haneveld and Van der Vlerk (Comput Manage Sci 3:245–269, 2006) for ICCs, and by Künzi-Bay and Mayer (Comput Manage Sci 3:3–27, 2006) for CVaR minimization. These concepts are taken into consideration to propose representations and solution methods for the above class of SSD based models. We describe a cutting plane based solution algorithm and outline implementation details. A computational study is presented, which demonstrates the effectiveness and the scale-up properties of the solution algorithm, as applied to the SSD model of Roman et al. (Math Program, Ser B 108:541–569, 2006).This study was funded by OTKA, Hungarian
National Fund for Scientific Research, project 47340; by Mobile Innovation Centre, Budapest University of Technology, project 2.2; Optirisk Systems, Uxbridge, UK and by BRIEF (Brunel University Research Innovation and Enterprise Fund)
One- and many-body effects on mirages in quantum corrals
Recent interesting experiments used scanning tunneling microscopy to study
systems involving Kondo impurities in quantum corrals assembled on Cu or noble
metal surfaces. The solution of the two-dimensional one-particle Schrodinger
equation in a hard wall corral without impurity is useful to predict the
conditions under which the Kondo effect can be projected to a remote location
(the quantum mirage). To model a soft circular corral, we solve this equation
under the potential W*delta(r-r0), where r is the distance to the center of the
corral and r0 its radius. We expand the Green's function of electron surface
states Gs0 for r<r0 as a discrete sum of contributions from single poles at
energies epsilon_i-I*delta_i. The imaginary part delta_i is the half-width of
the resonance produced by the soft confining potential, and turns out to be a
simple increasing function of epsilon_i. In presence of an impurity, we solve
the Anderson model at arbitrary temperatures using the resulting expression for
Gs0 and perturbation theory up to second order in the Coulomb repulsion U. We
calculate the resulting change in the differential conductance Delta dI/dV as a
function of voltage and space, in circular and elliptical corrals, for
different conditions, including those corresponding to recent experiments. The
main features are reproduced. The role of the direct hybridization between
impurity and bulk, the confinement potential, the size of the corral and
temperature on the intensity of the mirage are analyzed. We also calculate
spin-spin correlation functions.Comment: 13 pages, 12 figures, accepted for publication in Phys. Rev. B.
Calculations of spin correlations within an additional approximation adde
Total body topical 5-fluorouracil for extensive non-melanoma skin cancer
Background Topical 5-fluorouracil 5% cream is one of the treatment modalities for non-melanoma skin cancer (NMSC). There is a lack of suitable therapies to treat patients with extensive NMSC. In this paper we report two patients with extensive NMSC treated by total body application of topical 5-fluorouracil 5% cream. Observations Topical 5-fluorouracil 5% cream was applied twice daily to the total body, including normal appearing skin. During the treatment, weekly blood samples were taken for measurement of 5-fluorouracil levels. All samples showed a 5-fluorouracil level less than the detection level of 10 mu g/l. Total body 5-fluorouracil 5% cream was shown to be an effective treatment in our patients; the majority of lesions cleared in both patients. Conclusions In conclusion, total body topical 5-fluorouracil 5% cream application was successful in two patients with extensive NMSC. No detectable serum level of 5-fluorouracil could be determined. Pain and secondary infections were important side effects in our patients. However, in patients with extensive NMSC this treatment may be considered
Crystal chemistry search of multiferroics with the stereochemically active lone pair
On the basis of our previous studies of magnetoelectric ordering of BiFeO3,
TbMnO3, TbMn2O5 and BiMn2O5 we formulate the crystal chemistry criteria for the
search of multiferroics and reveal potential multiferroics Pb2Cu(OH)4Cl2,
Pb5Cr3F19, Mn(SeO3){\dot}H2O and BiPbSr2MnO6 each containing the ion with a
lone pair.Comment: 4 pages, 8 figures,submitted to J Supercond Nov Mag
Mars as a "natural laboratory" for studying surface activity on a range of planetary bodies
n/
Long-term aircraft noise exposure and risk of hypertension in postmenopausal women
Background: Studies of the association between aircraft noise and hypertension are complicated by inadequate control for potential confounders and a lack of longitudinal assessments, and existing evidence is inconclusive. Objectives: We evaluated the association between long-term aircraft noise exposure and risk of hypertension among post-menopausal women in the Women's Health Initiative Clinical Trials, an ongoing prospective U.S. cohort. Methods: Day-night average (DNL) and night equivalent sound levels (Lnight) were modeled for 90 U.S. airports from 1995 to 2010 in 5-year intervals using the Aviation Environmental Design Tool and linked to participant geocoded addresses from 1993 to 2010. Participants with modeled exposures ≥45 A-weighted decibels (dB [A]) were considered exposed, and those outside of 45 dB(A) who also did not live in close proximity to unmodeled airports were considered unexposed. Hypertension was defined as systolic/diastolic blood pressure ≥140/90 mmHg or inventoried/self-reported antihypertensive medication use. Using time-varying Cox proportional hazards models, we estimated hazard ratios (HRs) for incident hypertension when exposed to DNL or Lnight ≥45 versus <45 dB(A), controlling for sociodemographic, behavioral, and environmental/contextual factors. Results/discussion: There were 18,783 participants with non-missing DNL exposure and 14,443 with non-missing Lnight exposure at risk of hypertension. In adjusted models, DNL and Lnight ≥45 db(A) were associated with HRs of 1.00 (95% confidence interval [CI]: 0.93, 1.08) and 1.06 (95%CI: 0.91, 1.24), respectively. There was no evidence supporting a positive exposure-response relationship, and findings were robust in sensitivity analyses. Indications of elevated risk were seen among certain subgroups, such as those living in areas with lower population density (HRinteraction: 0.84; 95%CI: 0.72, 0.98) or nitrogen dioxide concentrations (HRinteraction: 0.82; 95%CI: 0.71, 0.95), which may indicate lower ambient/road traffic noise. Our findings do not suggest a relationship between aircraft noise and incident hypertension among older women in the U.S., though associations in lower ambient noise settings merit further investigation
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