Site-Selective Spectroscopy And Crystal-Field Analysis For Nd3+ In Strontium Fluorovanadate

Site‐selective spectroscopy reveals that Nd3+ ions occupy more than 40 different crystal‐field environments in Sr5(VO4)3F. Preferential energy transfer to the site responsible for 1 μm lasing occurs but becomes less complete with increasing temperature. The 4I and 4F3/2 Stark levels of the lasing site have been determined and an analysis of the crystal field performed. From the crystal‐field fitting parameters Bkq, a calculated energy‐level spectrum is determined up to 17 500 cm−1 with a rms deviation from the available experimental levels of 6 cm−1

Minimally Invasive Mitral Valve Surgery III: Training and Robotic-Assisted Approaches.

Minimally invasive mitral valve operations are increasingly common in the United States, but robotic-assisted approaches have not been widely adopted for a variety of reasons. This expert opinion reviews the state of the art and defines best practices, training, and techniques for developing a successful robotics program

Minimally Invasive Mitral Valve Surgery I: Patient Selection, Evaluation, and Planning.

Widespread adoption of minimally invasive mitral valve repair and replacement may be fostered by practice consensus and standardization. This expert opinion, first of a 3-part series, outlines current best practices in patient evaluation and selection for minimally invasive mitral valve procedures, and discusses preoperative planning for cannulation and myocardial protection

Minimally Invasive Mitral Valve Surgery II: Surgical Technique and Postoperative Management.

Techniques for minimally invasive mitral valve repair and replacement continue to evolve. This expert opinion, the second of a 3-part series, outlines current best practices for nonrobotic, minimally invasive mitral valve procedures, and for postoperative care after minimally invasive mitral valve surgery

GUIDE DES NÉGOCIATIONS – Décryptage des principaux résultats de la CdP25 (Chili/Madrid)

Le Guide des négociations est un document réalisé annuellement par l’OIF/IFDD pour accompagner les sessions de la Conférence des Parties (CdP) à la Convention-cadre des Nations Unies sur les changements climatiques (CCNUCC). Compte tenu du contexte inédit induit par la pandémie de Covid-19, et du report des sessions formelles à 2021, le présent document constitue plutôt un Guide de décryptage « passerelle » d’ici à la prochaine édition du Guide des négociations qui sera publié en amont de la 26e session de la Conférence des Parties (CdP26) (1-12 novembre 2021, Glasgow). Il reste toutefois une source précieuse pour offrir à chacun l’accès à une présentation analytique des enjeux. Dans ce cadre, ce document apparait en effet d’autant plus utile, voire nécessaire. Face à une situation à laquelle personne n’était préparé, l’ensemble des entités impliquées dans le cadre des négociations, dont certaines Parties elles-mêmes, n’ont pas la capacité de se tenir informées, ni de se préparer avec le plus d’efficacité possible à la reprise des sessions en présentiel prévue en 2021. Alors que l’urgence climatique ne peut souffrir d’aucun retard supplémentaire, et que d’importantes décisions devront aboutir dès la reprise des activités formelles, ce document entend ainsi s’inscrire dans une dynamique positive et constructive permettant de tendre vers une CdP26 réussie et ambitieuse. Le Guide propose, dans un premier temps, un décryptage des résultats clés de la dernière session de la Conférence des Parties (CdP25 – Chili/Madrid, 2019), en indiquant les perspectives associées aux prochains enjeux des négociations. Il présente ensuite un cadre de lecture indicatif des incidences de la pandémie sur le processus de la CCNUCC et des dispositifs inédits mis en place pour s’y adapter. Comme chaque année, le Guide bénéficie de l’apport d’un groupe d’auteurs et de contributeurs issus de différents pays de la Francophonie, impliqués dans les négociations sur le climat depuis de nombreuses années. Un Comité de relecture composé d’experts sélectionnés pour leur implication dans le processus des négociations permet, en outre, de s’assurer de la pertinence et de la rigueur des informations. L’ensemble des informations est actualisé à la date du 2 novembre 2020. Ce document a été rédigé par ENERGIES 2050 pour le compte de l’Institut de la Francophonie pour le développement durable (IFDD). Il est publié à titre d’information et ne reflète pas le point de vue de l’IFDD, ni celui du Secrétariat de la Convention, ni celui de la présidence de la CdP26. Ce Guide produit par l’IFDD est actualisé sur la base des informations disponibles à la date du 2 novembre 2020

Spectroscopic Characteristics Of Nd3+-Doped Strontium Fluorovanadate And Their Relationship To Laser Performance

High slope efficiency and low threshold laser performance have been achieved for both long pulsed and cw operation at 1.065 μm in Nd3+‐doped strontium fluorovanadate crystal, Nd3+:Sr5(VO4)3F, when pumped by narrow band pulsed Cr:LiSAF and cw Ti:sapphire lasers. However, there are inequivalent Nd3+ sites in the crystal. The absorption of Nd3+ ions in secondary sites, sites other than the site which contributes to lasing, may reduce the pumping efficiency and, consequently, the lasing efficiency. Strong concentration quenching of the Nd3+ 4F3/2 state was also observed reducing the quantum efficiency of the laser transition from this state

Spectroscopy And Laser Performance Of Nd Doped Gadolinium Lithium-Fluoride

A comprehensive investigation on the spectroscopic Properties and laser performance of Nd3+ doped GdLiF4 (GLF), a new laser crystal, is reported. Our high resolution absorption and emission spectra for GLF are nearly identical to those of Nd:LiYF4 (YLF), a well known laser crystal, strongly suggesting that the two crystals are isostructural. The laser performance of Nd:GLF is very similar to that of Nd:YLF. A maximum laser-pump-laser slope efficiency of 68% and 67% was obtained for low (1.0 at. %) and high (4.0 at. %) Nd concentration GLF respectively. Concentration quenching of the fluorescence decay time was observed and appears to be due to the dipole-dipole interaction between the isolated Nd3+ ions and Nd3+ ion pairs

Aorto-ventricular tunnel

Aorto-ventricular tunnel is a congenital, extracardiac channel which connects the ascending aorta above the sinutubular junction to the cavity of the left, or (less commonly) right ventricle. The exact incidence is unknown, estimates ranging from 0.5% of fetal cardiac malformations to less than 0.1% of congenitally malformed hearts in clinico-pathological series. Approximately 130 cases have been reported in the literature, about twice as many cases in males as in females. Associated defects, usually involving the proximal coronary arteries, or the aortic or pulmonary valves, are present in nearly half the cases. Occasional patients present with an asymptomatic heart murmur and cardiac enlargement, but most suffer heart failure in the first year of life. The etiology of aorto-ventricular tunnel is uncertain. It appears to result from a combination of maldevelopment of the cushions which give rise to the pulmonary and aortic roots, and abnormal separation of these structures. Echocardiography is the diagnostic investigation of choice. Antenatal diagnosis by fetal echocardiography is reliable after 18 weeks gestation. Aorto-ventricular tunnel must be distinguished from other lesions which cause rapid run-off of blood from the aorta and produce cardiac failure. Optimal management of symptomatic aorto-ventricular tunnel consists of diagnosis by echocardiography, complimented with cardiac catheterization as needed to elucidate coronary arterial origins or associated defects, and prompt surgical repair. Observation of the exceedingly rare, asymptomatic patient with a small tunnel may be justified by occasional spontaneous closure. All patients require life-long follow-up for recurrence of the tunnel, aortic valve incompetence, left ventricular function, and aneurysmal enlargement of the ascending aorta

Article 6 negotiations handbook for Eastern Africa

This paper is meant as a handbook for negotiators from East Africa to make important contributions to the Article 6 negotiations and the finalisation of the rulebook to represent their priorities and circumstances. It provides a summary of the history and status of current Article 6 negotiations and identifies and discusses issues that are relevant to Eastern African countries. Finally, negotiation strategies are discussed to support the positions of the Eastern African negotiators

San Francisco, California, seals on Seal Rocks

Color post card from Stella Ruess's collection, showing seals on the Seal Rocks near the Cliff House in San Francisco, California