Supercurrent through grain boundaries in the presence of strong correlations

Strong correlations are known to severely reduce the mobility of charge carriers near half-filling and thus have an important influence on the current carrying properties of grain boundaries in the high-$T_c$ cuprates. In this work we present an extension of the Gutzwiller projection approach to treat electronic correlations below as well as above half-filling consistently. We apply this method to investigate the critical current through grain boundaries with a wide range of misalignment angles for electron- and hole-doped systems. For the latter excellent agreement with experimental data is found. We further provide a detailed comparison to an analogous weak-coupling evaluation.Comment: 4 pages, 3 figure

Disorder Induced Stripes in d-Wave Superconductors

Stripe phases are observed experimentally in several copper-based high-Tc superconductors near 1/8 hole doping. However, the specific characteristics may vary depending on the degree of dopant disorder and the presence or absence of a low- temperature tetragonal phase. On the basis of a Hartree-Fock decoupling scheme for the t-J model we discuss the diverse behavior of stripe phases. In particular the effect of inhomogeneities is investigated in two distinctly different parameter regimes which are characterized by the strength of the interaction. We observe that small concen- trations of impurities or vortices pin the unidirectional density waves, and dopant disorder is capable to stabilize a stripe phase in parameter regimes where homogeneous phases are typically favored in clean systems. The momentum-space results exhibit universal features for all coexisting density-wave solutions, nearly unchanged even in strongly disordered systems. These coexisting solutions feature generically a full energy gap and a particle-hole asymmetry in the density of states.Comment: 28 pages, 8 figure

A Bibliometric Study of Authorship and Collaboration Trends Over the Past 30 Years in Four Major Musculoskeletal Science Journals

This study explored changes in bibliometric variables over the last 30 years for four major musculoskeletal science journals (BONE®), Calcified Tissue International® (CTI®), Journal of Bone and Mineral Research® (JBMR®), and Journal of Orthopaedic Research® (JOR®), with a specific focus on author gender. Bibliometric data were collected for all manuscripts in 1985 (BONE®, CTI®, JOR®), 1986 (JBMR®), 1995, 2005, and 2015; 2776 manuscripts met inclusion criteria. Manuscripts from Europe were more often published in BONE® or CTI®, while those from North America in JBMR® or JOR®. All journals demonstrated an increase over time in the number of authors (3.67–7.3), number of countries (1.1–1.4), number of institutions (1.4–3.1), and number of references (25.1–45.4). The number of manuscript pages increased (6.6–8.9) except for JOR® which showed a decline. CTI® had the lowest number of authors (4.9 vs. 5.6–6.8). There was a change in the corresponding author position from first to last for all journals; this change was highest for CTI® (35%) and lowest for BONE® (14.0%). All journals demonstrated an increase over time in female authors; however, CTI® was the highest amongst these four journals. The percentage of female first authors rose from 24.6 to 44.3% (CTI® 29.1–52.3%). The percentage of corresponding female authors rose from 17.5 to 33.6% (CTI® 22.9–40.0%). The proportion of female authors is increasing, likely reflecting the increasing number of women obtaining doctorates in science, medicine, and engineering

Crossover from hc/e to hc/2e current oscillations in rings of s-wave superconductors

We analyze the crossover from an hc/e-periodicity of the persistent current in flux threaded clean metallic rings towards an hc/2e-flux periodicity of the supercurrent upon entering the superconducting state. On the basis of a model calculation for a one-dimensional ring we identify the underlying mechanism, which balances the hc/e versus the hc/2e periodic components of the current density. When the ring circumference exceeds the coherence length of the superconductor, the flux dependence is strictly hc/2e periodic. Further, we develop a multi-channel model which reduces the Bogoliubov - de Gennes equations to a one-dimensional differential equation for the radial component of the wave function. The discretization of this differential equation introduces transverse channels, whose number scales with the thickness of the ring. The periodicity crossover is analyzed close the critical temperature

Federated Learning Based Proactive Content Caching in Edge Computing

This is the author accepted manuscript. the final version is available from IEEE via the DOI in this recordContent caching is a promising approach in edge computing to cope with the explosive growth of mobile data on 5G networks, where contents are typically placed on local caches for fast and repetitive data access. Due to the capacity limit of caches, it is essential to predict the popularity of files and cache those popular ones. However, the fluctuated popularity of files makes the prediction a highly challenging task. To tackle this challenge, many recent works propose learning based approaches which gather the users' data centrally for training, but they bring a significant issue: users may not trust the central server and thus hesitate to upload their private data. In order to address this issue, we propose a Federated learning based Proactive Content Caching (FPCC) scheme, which does not require to gather users' data centrally for training. The FPCC is based on a hierarchical architecture in which the server aggregates the users' updates using federated averaging, and each user performs training on its local data using hybrid filtering on stacked autoencoders. The experimental results demonstrate that, without gathering user's private data, our scheme still outperforms other learning-based caching algorithms such as m-epsilon-greedy and Thompson sampling in terms of cache efficiency.Engineering and Physical Sciences Research Council (EPSRC)National Key Research and Development Program of ChinaNational Natural Science Foundation of ChinaEuropean Union Seventh Framework Programm

Flux Periodicities in Loops of Nodal Superconductors

Supercurrents in superconducting flux threaded loops are expected to oscillate with the magnetic flux with a period of hc/2e. This is indeed true for s-wave superconductors larger than the coherence length xi_0. Here we show that for superconductors with gap nodes, there is no such strict condition for the supercurrent to be hc/2e rather than hc/e periodic. For nodal superconductors, the flux induced Doppler shift of the near nodal states leads to a flux dependent occupation probability of quasi-particles circulating clockwise and counter clockwise around the loop, which leads to an hc/e periodic component of the supercurrent, even at zero temperature. We analyze this phenomenon on a cylinder in an approximative analytic approach and also numerically within the framework of the BCS theory. Specifically for d-wave pairing, we show that the hc/e periodic current component decreases with the inverse radius of the loop and investigate its temperature dependence

Bibliometric Analysis of Female Authorship Trends and Collaboration Dynamics Over JBMR's 30-Year History

In academia, authorship is considered a currency and is important for career advancement. As the Journal of Bone and Mineral Research (JBMR) is the highest-ranked journal in the field of bone, muscle, and mineral metabolism and is the official publication of the American Society for Bone and Mineral Research, we sought to examine authorship changes over JBMR's 30-year history. Two bibliometric methods were used to collect the data. The “decade method” included all published manuscripts throughout 1 year in each decade over the past 30 years starting with the inaugural year, yielding 746 manuscripts for analysis. The “random method” examined 10% of published manuscripts from each of the 30 years, yielding 652 manuscripts for analysis. Using both methods, the average number of authors per manuscript, numerical location of the corresponding author, number of collaborating institutions, number of collaborating countries, number of printed manuscript pages, and the number of times each manuscript was cited all significantly increased between 1986 and 2015 (p < 10−4). Using the decade method, there was a significant increase in the percentage of female first authors over time from 35.8% in 1986 to 47.7% in 2015 (p = 0.02), and this trend was confirmed using the random method. The highest percentage of female first authors in 2015 was in Europe (60.0%), and Europe also had the most dramatic increase in female first authors over time (more than double in 2015 compared with 1986). Likewise, the overall number of female corresponding authors significantly increased during the past 30 years. With the increasing demands of publishing in academic medicine, understanding changes in publishing characteristics over time and by geographical region is important. These findings highlight JBMR's authorship trends over the past 30 years and demonstrate those countries having the most changes and where challenges still exist

Efficacy of frovatriptan versus other triptans in the acute treatment of menstrual migraine: pooled analysis of three double-blind, randomized, crossover, multicenter studies

The objective of this study was to review the efficacy and safety of frovatriptan (F) versus rizatriptan (R), zolmitriptan (Z) and almotriptan (A), in women with menstrually related migraine (IHS criteria) through a pooled analysis of three individual studies. Subjects with a history of migraine with or without aura were randomized to F 2.5 mg or R 10 mg (study 1), F or Z 2.5 mg (study 2), and F or A 12.5 mg (study 3). The studies had an identical multicenter, randomized, double-blind, crossover design. After treating three episodes of migraine in no more than 3 months with the first treatment, patients had to switch to the next treatment for other 3 months. 346 subjects formed intention-to-treat population of the main study; 280 of them were of a female gender, 256 had regular menses and 187 were included in the menstrual migraine subgroup analysis. Rate of pain free at 2, 4 and 24 h was 23, 52 and 67 % with F and 30, 61 and 66 % with comparators (P = NS). Pain relief episodes at 2, 4 and 24 h were 37, 60 and 66 % for F and 43, 55 and 61 % for comparators (P = NS). Rate of recurrence was significantly (P < 0.05) lower under F either at 24 h (11 vs. 24 % comparators) or at 48 h (15 vs. 26 % comparators). Number of menstrual migraine attacks associated with drug-related adverse events was equally low (P = NS) between F (5 %) and comparators (4 %)

Production and characterisation of environmentally relevant microplastic test materials derived from agricultural plastics

Soil environments across the globe, particularly in agricultural settings, have now been shown to be contaminated with microplastics. Agricultural plastics – such as mulching films – are used in close or direct contact with soils and there is growing evidence demonstrating that they represent a potential source of microplastics. There is a demand to undertake fate and effects studies to understand the behaviour and potential long-term ecological risks of this contamination. Yet, there is a lack of test materials available for this purpose. This study describes the manufacture and characterisation of five large (1–40 kg) batches of microplastic test materials derived from agricultural mulching films. Batches were produced from either polyethylene-based conventional mulching films or starch-polybutadiene adipate terephthalate blend mulching films that are certified biodegradable in soil. Challenges encountered and overcome during the micronisation process provide valuable insights into the future of microplastic test material generation from these material types. This includes difficulties in micronising virgin polyethylene film materials. All five batches were subjected to a thorough physical and chemical characterisation - both of the original virgin films and the subsequent microplastic particles generated - including a screening for the presence of chemical additives. This is a critical step to provide essential information for interpreting particle fate or effects in scientific testing. Trade-offs between obtaining preferred particle typologies and time and cost constraints are elucidated. Several recommendations emerging from the experiences gained in this study are put forward to advance the research field towards greater harmonisation and utilisation of environmentally relevant test materials