Electron Pair Localization Function (EPLF) for Density Functional Theory and ab Initio Wave Function-Based Methods: A New Tool for Chemical Interpretation

International audienceWe present a modified definition of the Electron Pair Localization Function (EPLF), initially defined within the framework of quantum Monte Carlo approaches [Scemama, A.; Caffarel, M.; Chaquin, P. J. Chem. Phys. 2004, 121, 1725] to be used in Density Functional Theories (DFT) and ab initio wave-function-based methods. This modified version of the EPLF--while keeping the same physical and chemical contents--is built to be analytically computable with standard wave functions or Kohn−Sham representations. It is illustrated that the EPLF defines a simple and powerful tool for chemical interpretation via selected applications including atomic and molecular closed-shell systems, σ and π bonds, radical and singlet open-shell systems, and molecules having a strong multiconfigurational character. Some applications of the EPLF are presented at various levels of theory and compared to Becke and Edgecombe's Electron Localization Function (ELF). Our open-source parallel software implementation of the EPLF opens the possibility of its use by a large community of chemists interested in the chemical interpretation of complex electronic structures

Structural and optical properties of a neutral Nickel bisdithiolene complex: density functional versus ab initio methods

International audienceDensity functional theory (DFT) and ab initio computations are applied to examine different properties of diamagnetic, square planar neutral nickel complexes that contain two bidentate ligands derived from bis ((ethylene)-1,2-dithiolato) ligands. Geometry, vibrational spectra (IR and Raman) are well reproduced in the density functional framework whereas TD-DFT methods are clearly insufficient to reproduce absorption properties. Multiconfigurational perturbation theory based on a complete active space self-consistent field wave function, i.e. MRPT2 and MRPT4 methods, reveal the pronounced multiconfigurational character of the ground state wave function. The singlet-triplet energy gap, the energy gained from symmetry breaking and the singlet diradical character are discussed in the DFT and ab initio frameworks. The complex of interest does not display a strong singlet diradical character. This molecule having a peculiar electronic structure; strong delocalization as shown by a new electron pair localization function analysis (EPLF); exemplifies the fragility of the TD-DFT method and thus, caution should be taken in the determination of the energetic properties of such compound

Maritime Transportation: Let\u27s Slow Down a Bit

Maritime transportation is a major contributor to the world economy, but has significant social and environmental impacts. Each impact calls for different technical or operational solutions. Amongst these solutions, we found that speed reduction measures appear to mitigate several issues: (1) collision with wildlife; (2) collision with non-living objects; (3) underwater noise; (4) invasive species; and (5) gas emission. We do not pretend that speed reduction is the best solution for each individual issue mentioned in this paper, but we argue that it could be a key solution to significantly reduce these threats all together. Further interdisciplinary research is required to balance private economic costs of speed reduction measures with environmental and social benefits emerging from all mitigated issues

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

Conjoined twins: what ultrasound may add to management

Introduction: Conjoined twins occur in approximately 0.2:10,000 births; the obstetrician and sonographer only rarely examine them. In Western countries, discovery of conjoined twins is often made by the end of the first trimester; however, in the third world, conjoined twins are often discovered only at birth. Objective: To evaluate how ultrasound techniques, when possibly available, may improve management and counseling when conjoined twins are confirmed. Material and Methods: The authors report two different cases of union of two equal twins with sole umbilical cord. Results: The two cases presented with non contributive medical history and no prior teratogen exposure and an unfavorable prognosis. Early discovery of viable conjoined twins permits assessment of the best route of delivery and a planning for serial sonography and fast MRI to plan eventual separation surgery or fetus after-birth surviving possibilities

Importance of Early Diagnosis and Care in Knee Dislocations Associated with Vascular Injuries

International audienceBackground: Arterial injury secondary to acute knee dislocation (KD) is a rare but devastative complication. The aim of this study is to evaluate functional sequelae and factors of poor prognosis.Methods: A retrospective monocentric series of consecutive KD with acute ischemia by popliteal artery injury was analyzed between 2005 and 2017. The main outcome was the amputation rate.Results: Sixteen dislocations were included. Nine (56%) were due to public road accidents, 5 (31%) were due to falls from height, and 2 (13%) were due to sports injuries. Dislocation had occurred in the posterior location in 8 (50%) cases. Regarding arterial injury, there were 7 (44%) ruptures, 7 (44%) dissections, and 2 (13%) isolated thromboses. Eleven (69%) KDs with vascular trauma were associated with signs of acute ischemia. Revascularization was achieved by anatomical venous bypass in 14 (88%), resection and direct anastomosis in one (6%), and isolated thrombectomy in one (6%). Median time to surgery (time between trauma and vascular repair) was 7 hours (3.25-60.92 hours). Primary revascularization was performed in 12 (75%) cases. In three cases (19%), orthopedic reduction and stabilization were performed first. In one case, (6%) three-step management with vascular shunt at first, then with knee stabilization, and finally vascular bypass was carried out. Stabilization was achieved by using an external fixator in 13 (82%) cases, by open reduction and internal fixation in one case (6%), by ligamentoplasty in one (6%), and by using a long leg cast in one (6%). Fasciotomy was required in 12 (75%) cases. Two patients had early vascular complications, and 2 had early systemic complications. Three secondary transfemoral amputations were performed. Median follow-up duration was 23 months. No secondary amputation was recorded. At the end of follow-up, functional outcomes were evaluated using the Oxford Knee Score (OKS). The median OKS was 30 versus the pretrauma median OKS of 47 (P < 0.00028). No risk factor associated with limb amputation has been highlighted.Conclusions: Analysis of these results provided indications for therapeutic management of this condition. This study shows poor functional outcomes because of severity of vascular lesion in patients with orthopedic trauma but with healthy arteries

Maritime transportation: Let's slow down a bit

International audienceMaritime transportation is a major contributor to the world economy, but has significant social and environmental impacts. Each impact calls for different technical or operational solutions. Amongst these solutions, we found that speed reduction measures appear to mitigate several issues: (1) collision with wildlife; (2) collision with non-living objects; (3) underwater noise; (4) invasive species; and (5) gas emission. We do not pretend that speed reduction is the best solution for each individual issue mentioned in this paper, but we argue that it could be a key solution to significantly reduce these threats all together. Further interdisciplinary research is required to balance private economic costs of speed reduction measures with environmental and social benefits emerging from all mitigated issues

Maritime Transportation: Let\u27s Slow Down a Bit

Maritime transportation is a major contributor to the world economy, but has significant social and environmental impacts. Each impact calls for different technical or operational solutions. Amongst these solutions, we found that speed reduction measures appear to mitigate several issues: (1) collision with wildlife; (2) collision with non-living objects; (3) underwater noise; (4) invasive species; and (5) gas emission. We do not pretend that speed reduction is the best solution for each individual issue mentioned in this paper, but we argue that it could be a key solution to significantly reduce these threats all together. Further interdisciplinary research is required to balance private economic costs of speed reduction measures with environmental and social benefits emerging from all mitigated issues