Mott transition, antiferromagnetism, and unconventional superconductivity in layered organic superconductors

The phase diagram of the layered organic superconductor $\kappa$-(ET)$_{2}$Cu[N(CN)$_{2}$]Cl has been accurately measured from a combination of $^{1}$H NMR and AC susceptibility techniques under helium gas pressure. The domains of stability of antiferromagnetic and superconducting long-range orders in the pressure {\it vs} temperature plane have been determined. Both phases overlap through a first-order boundary that separates two regions of inhomogeneous phase coexistence. The boundary curve is found to merge with another first order line related to the metal-insulator transition in the paramagnetic region. This transition is found to evolve into a crossover regime above a critical point at higher temperature. The whole phase diagram features a point-like region where metallic, insulating, antiferromagnetic and non s-wave superconducting phases all meet.Comment: 4 pages, 6 figures, Revte

A set of moment tensor potentials for zirconium with increasing complexity

Machine learning force fields (MLFFs) are an increasingly popular choice for atomistic simulations due to their high fidelity and improvable nature. Here, we propose a hybrid small-cell approach that combines attributes of both offline and active learning to systematically expand a quantum mechanical (QM) database while constructing MLFFs with increasing model complexity. Our MLFFs employ the moment tensor potential formalism. During this process, we quantitatively assessed structural properties, elastic properties, dimer potential energies, melting temperatures, phase stability, point defect formation energies, point defect migration energies, free surface energies, and generalized stacking fault (GSF) energies of Zr as predicted by our MLFFs. Unsurprisingly, model complexity has a positive correlation with prediction accuracy. We also find that the MLFFs wee able to predict the properties of out-of-sample configurations without directly including these specific configurations in the training dataset. Additionally, we generated 100 MLFFs of high complexity (1513 parameters each) that reached different local optima during training. Their predictions cluster around the benchmark DFT values, but subtle physical features such as the location of local minima on the GSFE surface are washed out by statistical noise

New Ultra-minimally Invasive Surgical Treatment for Benign Prostatic Hyperplasia: A Systematic Review and Analysis of Comparative Outcomes

Context: Benign prostatic hyperplasia (BPH) associated with lower urinary tract symptoms (LUTS) is diagnosed in up to 80% of men during their lifetime. Several novel ultra-minimally invasive surgical treatments (uMISTs) for BPH/benign prostatic obstruction (BPO) have become available over the past 5 yr. Objective: To evaluate the perioperative and functional outcomes of recently introduced uMISTs for BPH/BPO, including Urolift, Rezūm, temporary implantable nitinol device, prostatic artery embolization (PAE), and intraprostatic injection. Evidence acquisition: A systematic literature search was conducted in December 2020 using Medline (via PubMed), Embase (via Ovid), Scopus, and Web of Science (registered on PROSPERO as CRD42021225014). The search strategy used PICO criteria and article selection was conducted in accordance with the PRISMA guidelines. The risk of bias and the quality of the articles included were assessed. A dedicated data extraction form was used to collect the data of interest. Pooled and cumulative analyses were performed to compare perioperative and functional outcomes between study groups. A random-effects model using the DerSimonian and Laird method was used to evaluate heterogeneity. Stata version 15.0 software was used for all statistical analyses. Evidence synthesis: The initial electronic search identified 3978 papers, of which 48 ultimately met the inclusion criteria and were included in the analysis. Pooled analysis revealed a uMIST benefit in terms of International Prostate Symptom Score (IPSS; −9.81 points, 95% confidence interval [CI] −11.37 to −8.25 at 1 mo; −13.13 points, 95% CI −14.98 to −11.64 at 12 mo), maximum flow rate (from +3.66 ml/s, 95% CI 2.8–4.5 to +4.14 ml/s, 95% CI 0.72–7.56 at 12 mo), and postvoid residual volume (−10.10 ml, 95% CI −27.90 to 7.71 at 12 mo). No negative impact was observed on scores for the International Index of Erectile Function-5, Male Sexual Health Questionnaire-Ejaculatory Dysfunction bother and function scales (overall postintervention change in pooled median score of 1.88, 95% CI 1.34–2.42 at the start of follow-up; and 1.04, 95% CI 0.28–1.8 after 1 yr), or the IPSS-Quality of Life questionnaire. Conclusions: Novel uMISTs can yield fast and effective relief of LUTS without affecting patient quality of life. Only Rezūm, UroLift, and PAE had a minimal impact on patients’ sexual function with respect to baseline, especially regarding preservation of ejaculation. Patient summary: We reviewed outcomes for recently introduced ultra-minimally invasive surgical treatments for patients with lower urinary tract symptoms caused by benign prostate enlargement or obstruction. The evidence suggests that these novel techniques are beneficial in terms of controlling symptoms while preserving sexual function. Take Home Message: Novel ultra-minimally invasive treatments can yield fast and effective relief of lower urinary tract symptoms without affecting a patient's quality of life

Large-scale replication study reveals a limit on probabilistic prediction in language comprehension

Do people routinely pre-activate the meaning and even the phonological form of upcoming words? The most acclaimed evidence for phonological prediction comes from a 2005 Nature Neuroscience publication by DeLong, Urbach and Kutas, who observed a graded modulation of electrical brain potentials (N400) to nouns and preceding articles by the probability that people use a word to continue the sentence fragment (‘cloze’). In our direct replication study spanning 9 laboratories (N=334), pre-registered replication-analyses and exploratory Bayes factor analyses successfully replicated the noun-results but, crucially, not the article-results. Pre-registered single-trial analyses also yielded a statistically significant effect for the nouns but not the articles. Exploratory Bayesian single-trial analyses showed that the article-effect may be non-zero but is likely far smaller than originally reported and too small to observe without very large sample sizes. Our results do not support the view that readers routinely pre-activate the phonological form of predictable words

Using a sensitivity analysis of a weed dynamics model to develop sustainable cropping systems. II. Long-term effect of past crops and management techniques on weed infestation

International audienceBoth scientists and farmers are confronted by a similar question: which current and past cropping system components will influence the present weed flora, and how? This information is necessary to optimize both cropping systems for weed control, and quality and cost in surveys and monitoring schemes. The present study addressed these questions with a sensitivity analysis to input variables of a cropping system model, ALOMYSYS, that predicts weed dynamics in interaction with pedo-climatic conditions. The study ranked cropping system components according to their impact on weed infestation in winter wheat, showing for instance that though crop succession was crucial, current and past tillage strategies influenced grass weed densities even more. Crops were not only ranked as a function of the resulting weed risk but the latter was also linked to crop species traits, i.e. crop type, usual sowing period and emergence speed. A previous winter v. spring crop thus increased weed density by 72% in the following winter wheat; a late-sown v. early sown winter crop by 26%, a slow v. fast-emerging winter crop by 17%, and a lower competitive ability by 9%. Similarly, the characteristics of each crop management technique (tillage, catch crop, secondary crop, mowing, mechanical weeding, herbicides, nitrogen fertilizer, manure and harvest) were quantified. For instance, the timing of the first tillage operation was crucial prior to the analysed winter wheat crop while the choice of the tool used even 5 years previously still influenced weed infestation in the current year; a catch crop prior to previous spring sown crops reduced the current infestation regardless of catch crop sowing dates and densities, but the reductive effect could be lost if the field was tilled several times to destroy the catch crop. The advice synthesized here and in a companion paper (Colbach & Meziere 2012). will be valuable to design innovative, integrated cropping systems, indicating (1) which cropping system components to modify to produce the largest effect, (2) for how long past practices must be considered when choosing current options and (3) the optimal options for the different management techniques. Points (1) and (2) are also valuable to identify data to record in surveys, though still resulting in a total of 232 variables. In a second step, these detailed variables were therefore simplified and aggregated to determine a smaller set of 22 synthetic variables easily recorded in surveys, such as the proportion of winter and spring crops during the last 10 years (instead of the actual crop sequence), the proportion of crops sown in summer, early autumn, late autumn, early spring and late spring during the last 5 years (instead of exact sowing dates), the ploughing frequency (instead of ploughing dates and characteristics), the mean number of herbicide sprayings per year (instead of dates), etc. This reduced survey list will reduce the cost of surveys as well as increase the number and quality of surveys as more farmers will be ready to participate and there will be fewer uncertainties in the answers

Mott transition, antiferromagnetism, and unconventional superconductivity in layered organic superconductors

International audienceThe pressure vs temperature phase diagram of the layered organic superconducting family κ-(BEDT-TTF)2X is accurately determined by investigating the NMR and AC susceptibility properties of the anion substituted compound X=Cu[N(CN)2]Cl under helium gas pressure. A first order boundary between antiferromagnetism and superconductivity is established which is found to evolve into a first order metal–insulator transition line in the paramagnetic domain. This latter transition line is in turn ending in a critical point above which a mere crossover is retrieved. The whole phase diagram features a point-like region at which metallic, insulating, antiferromagnetic and unconventional superconducting phases all meet

Two-dimensional organic superconductors studied by NMR under pressure.

International audienceThe (BEDT)2X family of layered superconductors is one of the largest among nearly 50 org. superconductors currently known. One of the advantages of the org. compds. as prototype materials for studying the mechanisms of supercond. is their relatively high sensitivity to hydrostatic pressure. We review recent NMR studies of these compds. using NMR under liq. and gas pressure. We focus on the low temp. part of the phase diagram where the physics is controlled by electronic correlations leading to a competition between magnetism and supercond. This interplay between different ground states is shown by the observation of a pseudo-gap and antiferromagnetic fluctuations and can be finely tuned by the application of pressure. Using a gas pressure system gives the unique possibility of sweeping the pressure at low temp. Recently we used this technique to study the AF-SC boundary and established the existence of a first order transition line between the superconducting and antiferromagnetic state

Mott transition in the organic compound κ-(BEDT-TTF) 2 Cu[ N(CN) 2 ] Cl: An evidence for two energy scales

International audienceWe We have performed in-plane transport measurements on the two-dimensional organic salt κ-(BEDT-TTF) 2 Cu[N(CN) 2 ]Cl. A variable gas pressure technique allows for a detailed study of the changes in conductivity through the insulator-to-metal transition. We identify four different transport regimes as a function of pressure and temperature corresponding to insulating, semi-conducting,''bad metal'', and strongly correlated Fermi liquid behaviours