Parton distributions and new physics searches: the Drell–Yan forward–backward asymmetry as a case study

We present the first unquenched lattice-QCD calculation of the form factors for the decay \(B\rightarrow D^*\ell \nu \) at nonzero recoil. Our analysis includes 15 MILC ensembles with \(N_f=2+1\) flavors of asqtad sea quarks, with a strange quark mass close to its physical mass. The lattice spacings range from \(a\approx 0.15\) fm down to 0.045 fm, while the ratio between the light- and the strange-quark masses ranges from 0.05 to 0.4. The valence b and c quarks are treated using the Wilson-clover action with the Fermilab interpretation, whereas the light sector employs asqtad staggered fermions. We extrapolate our results to the physical point in the continuum limit using rooted staggered heavy-light meson chiral perturbation theory. Then we apply a model-independent parametrization to extend the form factors to the full kinematic range. With this parametrization we perform a joint lattice-QCD/experiment fit using several experimental datasets to determine the CKM matrix element \(|V_{cb}|\). We obtain \(\left| V_{cb}\right| = (38.40 \pm 0.68_{\text {th}} \pm 0.34_{\text {exp}} \pm 0.18_{\text {EM}})\times 10^{-3}\). The first error is theoretical, the second comes from experiment and the last one includes electromagnetic and electroweak uncertainties, with an overall \(\chi ^2\text {/dof} = 126/84\), which illustrates the tensions between the experimental data sets, and between theory and experiment. This result is in agreement with previous exclusive determinations, but the tension with the inclusive determination remains. Finally, we integrate the differential decay rate obtained solely from lattice data to predict \(R(D^*) = 0.265 \pm 0.013\), which confirms the current tension between theory and experiment.

     

Electrodes/Electrolyte Interfaces in the Presence of a Surface‐Modified Photopolymer Electrolyte: Application in Dye‐Sensitized Solar Cells

Since hundreds of studies on photoanodes and cathodes show that the electrode/electrolyte interfaces represent a key aspect at the base of dye‐sensitized solar cell (DSSC) performances, it is reported here that these interfaces can be managed by a smart design of the spatial composition of quasi‐solid electrolytes. By means of a cheap, rapid, and green process of photoinduced polymerization, composition‐tailored polymer electrolyte membranes (PEMs) with siloxane‐enriched surfaces are prepared, and their properties are thoroughly described. When assembled in DSSCs, the interfacial action promoted by the composition‐tailored PEMs enhances the photocurrent and fill factor values, thus increasing the global photovoltaic conversion efficiency with respect to the non‐modified PEMs. Moreover, the presence of the siloxane‐chain‐enriched surface increases the hydrophobicity and reduces the water vapor permeation into the device, thus enhancing the cell′s durability.     

Variability in UVB tolerances of melanized and nonmelanized cells of Cryptococcus neoformans and C. laurentii

Solar radiation is one of the major factors responsible for the control of fungus populations in the environment. Inactivation by UVA and UVB radiation is especially important for the control of fungi that disperse infective units through the air, including fungi such as Cryptococcus spp. that infect their vertebrate hosts by inhalation. Cryptococcus neoformans produces melanin in the presence of certain exogenous substrates such as l-3,4 dihydroxyphenylalanine and melanization may protect the fungus against biotic and abiotic environmental factors. In the present study, we investigated the effect of exposure to an UVB irradiance of 1000 mW m(-2) (biologically effective weighted irradiance) on the survival of melanized and nonmelanized cells of four strains of C. neoformans and four strains of C. laurentii. The relative survival (survival of cells exposed to radiation in relation to cells not exposed) of cells grown 2, 4, 6 or 8 days on medium with or without L-dopa was determined after exposure to UVB doses of 1.8 and 3.6 kJ m(-2). Both the irradiance spectrum and the intensities of those doses are environmentally realistic, and, in fact, occur routinely during summer months in temperate regions. Differences in tolerance to UVB radiation were observed between the C. neoformans and C. laurentii strains. The C. neoformans strains were more susceptible to UVB radiation than the C. laurentii strains. In C. neoformans, differences in tolerance to radiation were observed during development of both melanized and nonmelanized cells. For most treatments (strain, time of growth and UVB dose), there were virtually no differences in tolerances between melanized and nonmelanized cells, but when differences occurred they were smaller than those previously observed with UVC. In tests with two strains of C. laurentii, there was no difference in tolerance to UVB radiation between melanized and nonmelanized cells during 8 days of culture; and in tests with four strains for less culture time (4 days) there were no significant differences in tolerance between melanized and nonmelanized cells of any strain of this species.     

Electrical turbulence as a result of the critical curvature for propagation in cardiac tissue

In cardiac tissue, the propagation of electrical excitation waves is dependent on the active properties of the cell membrane (ionic channels) and the passive electrical properties of cardiac tissue (passive membrane properties, distribution of gap junctions, and cell shapes). Initiation of cardiac arrhythmias is usually associated with heterogeneities in the active and/or passive properties of cardiac tissue. However, as a result of the effect of wave front geometry (curvature) on propagation of cardiac waves, inexcitable anatomical obstacles, like veins and arteries, may cause the formation of self-sustained vortices and uncontrolled high-frequency excitation in normal homogeneous myocardium. (c) 1998 American Institute of Physics.     

A heuristic algorithm based on multi-assignment procedures for nurse scheduling

This paper tackles a Nurse Scheduling Problem which consists of generating work schedules for a set of nurses while considering their shift preferences and other requirements. The objective is to maximize the satisfaction of nurses’ preferences and minimize the violation of soft constraints. This paper presents a new deterministic heuristic algorithm, called MAPA (multi-assignment problem-based algorithm), which is based on successive resolutions of the assignment problem. The algorithm has two phases: a constructive phase and an improvement phase. The constructive phase builds a full schedule by solving successive assignment problems, one for each day in the planning period. The improvement phase uses a couple of procedures that re-solve assignment problems to produce a better schedule. Given the deterministic nature of this algorithm, the same schedule is obtained each time that the algorithm is applied to the same problem instance. The performance of MAPA is benchmarked against published results for almost 250,000 instances from the NSPLib dataset. In most cases, particularly on large instances of the problem, the results produced by MAPA are better when compared to best-known solutions from the literature. The experiments reported here also show that the MAPA algorithm finds more feasible solutions compared with other algorithms in the literature, which suggest that this proposed approach is effective and robust.     

Modeling dependence dynamics through copulas with regime switching

Measuring dynamic dependence between international financial markets has recently attracted great interest in financial econometrics because the observed correlations rose dramatically during the 2008–09 global financial crisis. Here, we propose a novel approach for measuring dependence dynamics. We include a hidden Markov chain (MC) in the equation describing dependence dynamics, allowing the unobserved time-varying dependence parameter to vary according to both a restricted ARMA process and an unobserved two-state MC. Estimation is carried out via the inference for the margins in conjunction with filtering/smoothing algorithms. We use block bootstrapping to estimate the covariance matrix of our estimators. Monte Carlo simulations compare the performance of regime switching and no switching models, supporting the regime-switching specification. Finally the proposed approach is applied to empirical data, through the study of the S&P500 (USA), FTSE100 (UK) and BOVESPA (Brazil) stock market indexes.     

Effects of hearing protector devices on speech intelligibility

The purpose of this study was to determine the influence of hearing protection devices (HPDs) on the understanding of speech in young adults with normal hearing, both in a silent situation and in the presence of ambient noise. The experimental research was carried out with the following variables: five different conditions of HPD use (without protectors, with two earplugs and with two earmuffs); a type of noise (pink noise); 4 test levels (60, 70, 80 and 90 dB[A]); 6 signal/noise ratios (without noise, +5, +10, zero, −5 and −10 dB); 5 repetitions for each case, totalling 600 tests with 10 monosyllables in each one. The variable measure was the percentage of correctly heard words (monosyllabic) in the test. The results revealed that, at the lowest levels (60 and 70 dB), the protectors reduced the intelligibility of speech (compared to the tests without protectors) while, in the presence of ambient noise levels of 80 and 90 dB and unfavourable signal/noise ratios (0, −5 and −10 dB), the HPDs improved the intelligibility. A comparison of the effectiveness of earplugs versus earmuffs showed that the former offer greater efficiency in respect to the recognition of speech, providing a 30% improvement over situations in which no protection is used. As might be expected, this study confirmed that the protectors' influence on speech intelligibility is related directly to the spectral curve of the protector's attenuation.     

Cd1-xMgxTe semiconductor nanocrystal alloys: Synthesis,preparation of nanocomposites with graphene-based materials,and electrochemical detection of lidocaine and epinephrine

Microchimica Acta - This work describes the synthesis of a glutathione-capped Cd1-xMgxTe semiconductor nanocrystal alloy in aqueous solution. The effects of reaction time and Cd:Mg molar proportion...     

Zinc Oxide Thin Films for Memristive Devices: A Review

Zinc Oxide (ZnO) thin films have been addressed as promising candidates for the fabrication of Resistive Random Access Memory devices, which are alternative to conventional charge-based flash memories. According to the filamentary conducting model and charge trapping/detrapping theory developed in the last decade, the memristive behavior of ZnO thin films is explained in terms of conducting filaments formed by metallic ions and/or oxygen vacancies, and their breaking through electrochemical redox reactions and/or recombination of oxygen vacancies/ions. A comparative review of the memristive properties of ZnO thin films grown by sputtering, atomic layer deposition (ALD), pulsed laser deposition (PLD), and sol-gel methods is here proposed. Sputtered ZnO thin films show promising resistive switching behaviors, showing high on/off ratios (10–10⁴), good endurance, and low operating voltages. ALD is also indicated to be useful for growing conformal ZnO layers with atomic thickness control, resulting in important resistive switching characteristics, such as relatively high on/off ratios and low operating voltages. High insulating epitaxial ZnO thin films can be obtained by PLD, showing reliable switching properties at low voltages and with good retention. On the contrary, the sol-gel approach generally results in ZnO thin films with poor resistive switching behaviors. Nevertheless, thin films derived from ZnO NPs show improved switching performances, with higher on/off ratios and lower operating voltages. Independently of the synthetic approach, doped ZnO thin films exhibit better resistive switching behaviors than pristine ones, coupling a strong increase of the on/off ratio with a more stable switching response.     

Mineralogical and thermal characterization of soft rock from Campinas,Brazil

Journal of Thermal Analysis and Calorimetry - In this study, the main purpose was the mineralogical and thermal characterization of clayey siltites sampled in a quarry located near Viracopos...