605 research outputs found
Residual absorption at zero temperature in d-wave superconductors
In a d-wave superconductor with elastic impurity scattering, not all the
available optical spectral weight goes into the condensate at zero temperature,
and this leads to residual absorption. We find that for a range of impurity
parameters in the intermediate coupling regime between Born (weak) and unitary
(strong) limit, significant oscillator strength remains which exhibits a cusp
like behavior of the real part of the optical conductivity with upward
curvature as a function of frequency, as well as a quasilinear temperature
dependence of the superfluid density. The calculations offer an explanation of
recent data on ortho-II YBaCuO which has been considered
anomalous.Comment: Accepted for publication by Phys. Rev. B 7 Pages and 4 Figure
Chemisorption of H2O and CO2 on hydrotalcites for sorptionenhanced water-gas-shift processes
Thermogravimetric analysis and breakthrough experiments in a packed bed reactor were used to validate a developed adsorption model to describe the cyclic working capacity of CO2 and H2O on a potassium-promoted hydrotalcite, a very promising adsorbent for sorption-enhanced water-gas-shift applications. Four different adsorption sites (two sites for CO2, one site for H2O and one equilibrium site for both species) were required to describe the mass changes observed in the TGA experiments. The TGA experiments were carried out at operating temperatures between 300 and 500 °C, while the total pressure in the reactor was kept at atmospheric pressure. Cyclic working capacities for different sites and the influence of the operating conditions on the cyclic working capacity were studied using the developed model. A higher operating temperature leads to a significant increase in the cyclic working capacity of the sorbent for CO2 attributed to the increase in the desorption kinetics for CO2. The model was successfully validated with experiments in a packed bed reactor at different operating temperatures
Cochlear Implantation after Bacterial Meningitis in Infants Younger Than 9 Months
Objective. To describe the audiological, anesthesiological, and surgical key points of cochlear implantation after bacterial meningitis in very young infants. Material and Methods. Between 2005 and 2010, 4 patients received 7 cochlear implants before the age of 9 months (range 4–8 months) because of profound hearing loss after pneumococcal meningitis. Results. Full electrode insertions were achieved in all operated ears. The audiological and linguistic outcome varied considerably, with categories of auditory performance (CAP) scores between 3 and 6, and speech intelligibility rating (SIR) scores between 0 and 5. The audiological, anesthesiological, and surgical issues that apply in this patient group are discussed. Conclusion. Cochlear implantation in very young postmeningitic infants is challenging due to their young age, sequelae of meningitis, and the risk of cochlear obliteration. A swift diagnostic workup is essential, specific audiological, anesthesiological, and surgical considerations apply, and the outcome is variable even in successful implantations
Integrated silicon qubit platform with single-spin addressability, exchange control and robust single-shot singlet-triplet readout
Silicon quantum dot spin qubits provide a promising platform for large-scale
quantum computation because of their compatibility with conventional CMOS
manufacturing and the long coherence times accessible using Si enriched
material. A scalable error-corrected quantum processor, however, will require
control of many qubits in parallel, while performing error detection across the
constituent qubits. Spin resonance techniques are a convenient path to parallel
two-axis control, while Pauli spin blockade can be used to realize local parity
measurements for error detection. Despite this, silicon qubit implementations
have so far focused on either single-spin resonance control, or control and
measurement via voltage-pulse detuning in the two-spin singlet-triplet basis,
but not both simultaneously. Here, we demonstrate an integrated device platform
incorporating a silicon metal-oxide-semiconductor double quantum dot that is
capable of single-spin addressing and control via electron spin resonance,
combined with high-fidelity spin readout in the singlet-triplet basis.Comment: 10 pages, 4 figure
Spectroscopy and Biosensing with Optically Resonant Dielectric Nanostructures
Resonant dielectric nanoparticles (RDNs) made of materials with large
positive dielectric permittivity, such as Si, GaP, GaAs, have become a powerful
platform for modern light science, enabling various fascinating applications in
nanophotonics and quantum optics. In addition to light localization at the
nanoscale, dielectric nanostructures provide electric and magnetic resonant
responses throughout the visible and infrared spectrum, low dissipative losses
and optical heating, low doping effect and absence of quenching, which are
interesting for spectroscopy and biosensing applications. In this review, we
present state-of-the-art applications of optically resonant high-index
dielectric nanostructures as a multifunctional platform for light-matter
interactions. Nanoscale control of quantum emitters and applications for
enhanced spectroscopy including fluorescence spectroscopy, surface-enhanced
Raman scattering (SERS), biosensing, and lab-on-a-chip technology are surveyed.
We describe the theoretical background underlying these effects, overview
realizations of specific resonant dielectric nanostructures and hybrid
excitonic systems, and outlook the challenges in this field, which remain open
to future research
Free Energy and Magnetic Penetration Depth of a -Wave Superconductor in the Meissner State
We investigate the free energy and the penetration depth of a
quasi-two-dimensional d-wave superconductor in the presence of a weak magnetic
field by taking account of thermal, nonlocal and nonlinear effects. In an
approximation in which the superfluid velocity is assumed to be slowly
varying, the free energy is calculated and compared with available results in
several limiting cases. It is shown that either nonlocal or nonlinear effects
may cut off the linear- dependence of both the free energy and the
penetration depth in all the experimental geometries. At extremely low , the
nonlocal effects will also generically modify the linear dependence of the
penetration depth ("nonlinear Meissner effect") in most experimental
geometries, but for supercurrents oriented along the nodal directions, the
effect may be recovered. We compare our predictions with existing experiments
on the cuprate superconductors.Comment: 18 revtex pages with 4 eps figures, final versio
Antimicrobial susceptibility of Haemophilus influenzae, Neisseria meningitidis and Streptococcus pneumoniae isolates causing meningitis in The Netherlands, 1993-1994
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