A length scale for the superconducting Nernst signal above Tc_{c} in Nb0.15_{0.15}Si0.85_{0.85}

We present a study of the Nernst effect in amorphous superconducting thin films of Nb$_{0.15}$Si$_{0.85}$. The field dependence of the Nernst coefficient above T$_{c}$ displays two distinct regimes separated by a field scale set by the Ginzburg-Landau correlation length. A single function $F(\xi)$, with the correlation length as its unique argument set either by the zero-field correlation length (in the low magnetic field limit) or by the magnetic length (in the opposite limit), describes the Nernst coefficient. We conclude that the Nernst signal observed on a wide temperature ($30 \times T_c$) and field ($4 \times B_{c2}$) range is exclusively generated by short-lived Cooper pairs.Comment: 4 pages, 4 figure

Magnetic field-induced quantum superconductor-insulator transition in Nb0.15Si0.85Nb_{0.15}Si_{0.85}

A study of magnetic-field tuned superconductor-insulator transitions in amorphous $Nb_{0.15}Si_{0.85}$ thin films shows that quantum superconductor-insulator transitions are characterized by an unambiguous signature -- a kink in the temperature profile of the critical magnetic field. Using this criterion, we show that the nature of the magnetic-field tuned superconductor-insulator transition depends on the orientation of the field with respect to the film. For perpendicular magnetic field, the transition is controlled by quantum fluctuations with indications for the existence of a Bose insulator; while for parallel magnetic field, the transition is classical, driven by the breaking of Cooper pairs at the temperature dependent critical field $H_{c2}$.Comment: 5 pages, 4 figure

Incontinence : stress urinary incontinence treatment—surgery first?

A randomized trial involving 460 women with stress urinary incontinence compared physiotherapy with midurethral-sling surgery. We question whether the results, showing higher rates of improvement and cure for surgery than for physiotherapy, should change best practice and clinical practice guideline recommendations

Generative adversarial networks: an overview

Generative adversarial networks (GANs) provide a way to learn deep representations without extensively annotated training data. They achieve this by deriving backpropagation signals through a competitive process involving a pair of networks. The representations that can be learned by GANs may be used in a variety of applications, including image synthesis, semantic image editing, style transfer, image superresolution, and classification. The aim of this review article is to provide an overview of GANs for the signal processing community, drawing on familiar analogies and concepts where possible. In addition to identifying different methods for training and constructing GANs, we also point to remaining challenges in their theory and application

Observation of the Nernst signal generated by fluctuating Cooper pairs

Long-range order is destroyed in a superconductor warmed above its critical temperature (Tc). However, amplitude fluctuations of the superconducting order parameter survive and lead to a number of well established phenomena such as paraconductivity : an excess of charge conductivity due to the presence of short-lived Cooper pairs in the normal state. According to an untested theory, these pairs generate a transverse thermoelectric (Nernst) signal. In amorphous superconducting films, the lifetime of Cooper pairs exceeds the elastic lifetime of quasi-particles in a wide temperature range above Tc; consequently, the Cooper pairs Nernst signal dominate the response of the normal electrons well above Tc. In two dimensions, the magnitude of the expected signal depends only on universal constants and the superconducting coherence length, so the theory can be unambiguously tested. Here, we report on the observation of a Nernst signal in such a superconductor traced deep into the normal state. Since the amplitude of this signal is in excellent agreement with the theoretical prediction, the result provides the first unambiguous case for a Nernst effect produced by short-lived Cooper pairs

Background suppression in massive TeO2_2 bolometers with Neganov-Luke amplified light detectors

Bolometric detectors are excellent devices for the investigation of neutrinoless double-beta decay (0$\nu\beta\beta$). The observation of such decay would demonstrate the violation of lepton number, and at the same time it would necessarily imply that neutrinos have a Majorana character. The sensitivity of cryogenic detectors based on TeO$_2$ is strongly limited by the alpha background in the region of interest for the 0$\nu\beta\beta$ of $^{130}$Te. It has been demonstrated that particle discrimination in TeO$_2$ bolometers is possible measuring the Cherenkov light produced by particle interactions. However an event-by-event discrimination with NTD-based light detectors has to be demonstrated. We will discuss the performance of a highly-sensitive light detector exploiting the Neganov-Luke effect for signal amplification. The detector, being operated with NTD-thermistor and coupled to a 750 g TeO$_2$ crystal, shows the ability for an event-by-event identification of electron/gamma and alpha particles. The extremely low detector baseline noise, RMS 19 eV, demonstrates the possibility to enhance the sensitivity of TeO$_2$-based 0$\nu\beta\beta$ experiment to an unprecedented level

Nernst effect as a probe of superconducting fluctuations in disordered thin films

In amorphous superconducting thin films of $Nb_{0.15}Si_{0.85}$ and $InO_x$, a finite Nernst coefficient can be detected in a wide range of temperature and magnetic field. Due to the negligible contribution of normal quasi-particles, superconducting fluctuations easily dominate the Nernst response in the entire range of study. In the vicinity of the critical temperature and in the zero-field limit, the magnitude of the signal is in quantitative agreement with what is theoretically expected for the Gaussian fluctuations of the superconducting order parameter. Even at higher temperatures and finite magnetic field, the Nernst coefficient is set by the size of superconducting fluctuations. The Nernst coefficient emerges as a direct probe of the ghost critical field, the normal-state mirror of the upper critical field. Moreover, upon leaving the normal state with fluctuating Cooper pairs, we show that the temperature evolution of the Nernst coefficient is different whether the system enters a vortex solid, a vortex liquid or a phase-fluctuating superconducting regime.Comment: Submitted to New. J. Phys. for a focus issue on "Superconductors with Exotic Symmetries

Gap States in Dilute Magnetic Alloy Superconductors

We study states in the superconducting gap induced by magnetic impurities using self-consistent quantum Monte Carlo with maximum entropy and formally exact analytic continuation methods. The magnetic impurity susceptibility has different characteristics for T_{0} \alt T_{c0} and T_{0} \agt T_{c0} ($T_{0}$: Kondo temperature, $T_{c0}$: superconducting transition temperature) due to the crossover between a doublet and a singlet ground state. We systematically study the location and the weight of the gap states and the gap parameter as a function of $T_{0}/T_{c0}$ and the concentration of the impurities.Comment: 4 pages in ReVTeX including 4 encapsulated Postscript figure

Operational Framework to Quantify “Quality of Recycling” across Different Material Types

Many pledges and laws are setting recycling targets without clearly defining quality of recycling. Striving to close this gap, this study presents an operational framework to quantify quality of recycling. The framework comprises three dimensions: the Virgin Displacement Potential (VDP); In-Use Stocks Lifetime (IUSL); and Environmental Impact (EI). The VDP indicates to what extent a secondary material can be used as a substitute for virgin material; the IUSL indicates how much of a certain material is still functional in society over a given time frame, and the EI is a measure of the environmental impact of a recycling process. The three dimensions are aggregated by plotting them in a distance-to-target graph. Two example calculations are included on poly(ethylene terephthalate) (PET) and glass. The results indicate that the recycling of bottle and container glass collected via a deposit-refund system has the lowest distance-to-target, at 1.05, and, thus, the highest quality of recycling. For PET bottles, the highest quality of recycling is achieved in closed-loop mechanical recycling of bottles (distance to optimal quality of 0.96). Furthermore, sensitivity analysis indicates that certain parameters, e.g., the collection rate for PET bottles, can reduce the distance-to-target to 0.75 when all bottles are collected for recycling

First Season QUIET Observations: Measurements of CMB Polarization Power Spectra at 43 GHz in the Multipole Range 25 <= ell <= 475

The Q/U Imaging ExperimenT (QUIET) employs coherent receivers at 43GHz and 95GHz, operating on the Chajnantor plateau in the Atacama Desert in Chile, to measure the anisotropy in the polarization of the CMB. QUIET primarily targets the B modes from primordial gravitational waves. The combination of these frequencies gives sensitivity to foreground contributions from diffuse Galactic synchrotron radiation. Between 2008 October and 2010 December, >10,000hours of data were collected, first with the 19-element 43GHz array (3458hours) and then with the 90-element 95GHz array. Each array observes the same four fields, selected for low foregrounds, together covering ~1000deg^2. This paper reports initial results from the 43GHz receiver which has an array sensitivity to CMB fluctuations of 69uK sqrt(s). The data were extensively studied with a large suite of null tests before the power spectra, determined with two independent pipelines, were examined. Analysis choices, including data selection, were modified until the null tests passed. Cross correlating maps with different telescope pointings is used to eliminate a bias. This paper reports the EE, BB and EB power spectra in the multipole range ell=25-475. With the exception of the lowest multipole bin for one of the fields, where a polarized foreground, consistent with Galactic synchrotron radiation, is detected with 3sigma significance, the E-mode spectrum is consistent with the LCDM model, confirming the only previous detection of the first acoustic peak. The B-mode spectrum is consistent with zero, leading to a measurement of the tensor-to-scalar ratio of r=0.35+1.06-0.87. The combination of a new time-stream double-demodulation technique, Mizuguchi-Dragone optics, natural sky rotation, and frequent boresight rotation leads to the lowest level of systematic contamination in the B-mode power so far reported, below the level of r=0.1Comment: 19 pages, 14 figures, higher quality figures are available at http://quiet.uchicago.edu/results/index.html; Fixed a typo and corrected statistical error values used as a reference in Figure 14, showing our systematic uncertainties (unchanged) vs. multipole; Revision to ApJ accepted version, this paper should be cited as "QUIET Collaboration et al. (2011)