174 research outputs found
Self-reported disability and handicap after hearing-aid fitting and benefit of hearing aids: comparison of fitting procedures, degree of hearing loss, experience with hearing aids and uni- and bilateral fittings
Effective Lagrangians for BCS Superconductors at T=0
We show that the low frequency, long wavelength dynamics of the phase of the
pair field for a BCS-type s-wave superconductor at T=0 is equivalent to that of
a time-dependent non-linear Schr\"odinger Lagrangian (TDNLSL), when terms
required by Galilean invariance are included. If the modulus of the pair field
is also allowed to vary, the system is equivalent to two coupled TDNLSL's.
We also refer the interested reader to our earlier paper, `Nonlinear
Schrodinger equation for superconductors' [cond-mat/9312099], for a different
line of derivationComment: Latex, 13 page
BCS to Bose Crossover in Anisotropic Superconductors
In this work we use functional integral techniques to examine the nearest
neighbour attractive Hubbard model on a quasi-2D lattice. It is a simple
phenomenological model for the high-Tc cuprates that allows both extended
(non-local) s- and d-wave singlet superconductivity as well as mixed symmetry
states. The Hartree-Gor'kov mean field theory of the model has a finite
temperature phase diagram which shows a transition from pure s-wave to pure
d-wave superconductivity, via a mixed symmetry s+id state, as a function of
doping. Including Gaussian fluctuations we examine the crossover from
weak-coupling BCS superconductivity to the strong-coupling Bose-Einstein
condensation of composite s- or d-wave bosons and comment on the origin and
symmetry of the pseudogap.Comment: 20 pages inc. 13 figure
First Measurement of the Tensor Structure Function of the Deuteron
The \Hermes experiment has investigated the tensor spin structure of the
deuteron using the 27.6 GeV/c positron beam of \Hera. The use of a tensor
polarized deuteron gas target with only a negligible residual vector
polarization enabled the first measurement of the tensor asymmetry \At and
the tensor structure function \bd for average values of the Bj{\o}rken
variable and of the squared four-momentum transfer . The quantities \At and \bd are found to be
non-zero. The rise of \bd for decreasing values of can be interpreted to
originate from the same mechanism that leads to nuclear shadowing in
unpolarized scattering
Double hadron leptoproduction in the nuclear medium
First measurement of double-hadron production in deep-inelastic scattering
has been measured with the HERMES spectrometer at HERA using a 27.6 GeV
positron beam with deuterium, nitrogen, krypton and xenon targets. The
influence of the nuclear medium on the ratio of double-hadron to single-hadron
yields has been investigated. Nuclear effects are clearly observed but with
substantially smaller magnitude and reduced -dependence compared to
previously measured single-hadron multiplicity ratios. The data are in fair
agreement with models based on partonic or pre-hadronic energy loss, while they
seem to rule out a pure absorptive treatment of the final state interactions.
Thus, the double-hadron ratio provides an additional tool for studying
modifications of hadronization in nuclear matter
Subleading-twist effects in single-spin asymmetries in semi-inclusive deep-inelastic scattering on a longitudinally polarized hydrogen target
Single-spin asymmetries in the semi-inclusive production of charged pions in
deep-inelastic scattering from transversely and longitudinally polarized proton
targets are combined to evaluate the subleading-twist contribution to the
longitudinal case. This contribution is significantly positive for (\pi^+)
mesons and dominates the asymmetries on a longitudinally polarized target
previously measured by \hermes. The subleading-twist contribution for (\pi^-)
mesons is found to be small
Real-Time Contrast Enhancement to Improve Speech Recognition
An algorithm that operates in real-time to enhance the salient features of speech is described and its efficacy is evaluated. The Contrast Enhancement (CE) algorithm implements dynamic compressive gain and lateral inhibitory sidebands across channels in a modified winner-take-all circuit, which together produce a form of suppression that sharpens the dynamic spectrum. Normal-hearing listeners identified spectrally smeared consonants (VCVs) and vowels (hVds) in quiet and in noise. Consonant and vowel identification, especially in noise, were improved by the processing. The amount of improvement did not depend on the degree of spectral smearing or talker characteristics. For consonants, when results were analyzed according to phonetic feature, the most consistent improvement was for place of articulation. This is encouraging for hearing aid applications because confusions between consonants differing in place are a persistent problem for listeners with sensorineural hearing loss
Choosing between measures: comparison of EQ-5D, HUI2 and HUI3 in persons with hearing complaints
OBJECTIVES: To generate insight into the differences between utility measures EuroQol 5D (EQ-5D), Health Utilities Index Mark II (HUI2) and Mark III (HUI3) and their impact on the incremental cost-effectiveness ratio (ICER) for hearing aid fitting METHODS: Persons with hearing complaints completed EQ-5D, HUI2 and HUI3 at baseline and, when applicable, after hearing aid fitting. Practicality, construct validity, agreement, responsiveness and impact on the ICER were examined. RESULTS: All measures had high completion rates. HUI3 was capable of discriminating between clinically distinctive groups. Utility scores (n = 315) for EQ-5D UK and Dutch tariff (0.83; 0.86), HUI2 (0.77) and HUI3 (0.61) were significantly different, agreement was low to moderate. Change after hearing aid fitting (n = 70) for HUI2 (0.07) and HUI3 (0.12) was statistically significant, unlike the EQ-5D UK (0.01) and Dutch (0.00) tariff. ICERs varied from 647,209 euros/QALY for the EQ-5D Dutch tariff to 15,811 euros/QALY for HUI3. CONCLUSION: Utility scores, utility gain and ICERs heavily depend on the measure that is used to elicit them. This study indicates HUI3 as the instrument of first choice when measuring utility in a population with hearing complaints, but emphasizes the importance of a clear notion of what constitutes utility with regard to economic analyse
Growth of nanostructures by cluster deposition : a review
This paper presents a comprehensive analysis of simple models useful to
analyze the growth of nanostructures obtained by cluster deposition. After
detailing the potential interest of nanostructures, I extensively study the
first stages of growth (the submonolayer regime) by kinetic Monte-Carlo
simulations. These simulations are performed in a wide variety of experimental
situations : complete condensation, growth with reevaporation, nucleation on
defects, total or null cluster-cluster coalescence... The main scope of the
paper is to help experimentalists analyzing their data to deduce which of those
processes are important and to quantify them. A software including all these
simulation programs is available at no cost on request to the author. I
carefully discuss experiments of growth from cluster beams and show how the
mobility of the clusters on the surface can be measured : surprisingly high
values are found. An important issue for future technological applications of
cluster deposition is the relation between the size of the incident clusters
and the size of the islands obtained on the substrate. An approximate formula
which gives the ratio of the two sizes as a function of the melting temperature
of the material deposited is given. Finally, I study the atomic mechanisms
which can explain the diffusion of the clusters on a substrate and the result
of their mutual interaction (simple juxtaposition, partial or total
coalescence...)Comment: To be published Rev Mod Phys, Oct 99, RevTeX, 37 figure
Molecular mechanisms involved in pulmonary arterial hypertension development
Pulmonary arterial hypertension (PAH) is an elevation in pulmonary
arterial pressure, characterized by symptoms of dyspnea, chest pain, decrease in exercise tolerance-fatigue, syncope and, if untreated, PAH leads to right heart failure.
In PAH, there is an imbalance between mediators of vasodilation and
vasoconstriction (e.g. nitric oxide and prostacycline – potent vasodilators, platelet inhibitor and antimitogens are decreased in PAH, while thromboxane, vasoconstrictor and platelet activator is increased in PAH, resulting in smooth muscle hypertrophy of small vessels, adventitial and intimal proliferation, and plexiform vascular lesions with vascular thrombosis). Standard diagnostic procedures for PAH include physical examination, pulmonary function testing, radiographic imaging, transthoracic echocardiography, right heart catheterization. Current drugs include synthet c prostanoids (iloprost, epoprostenil, beraprost, treprostinil) – vasodilators and antiplatelet
agents. Phosphodiesterase-5 inhibitors decrease the breakdown of
cGMP, increasing its intracellular levels, leukotriene receptor antagonist, – zafirlukast, decreases pulmonary arterial and venous pressure. Endothelin receptor blockers, bosentan, decrease pulmonary vascular resistance and improve results of functional tests. Other treatments are: anticoagulants, calcium-channel blockers, positive airway pressure therapy for obstructive sleep apnea, or oxygen for hypoxemia, and surgery. In conclusion, although there are some promising drugs in therapy of PAH, there is a need to develop new ones, together with surgical approaches, in order to increase the survival of patients with PAH. Gene and cell therapy could be expected as future perspectives
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