Photoelectron Spectroscopy of Oppositely Charged Molecular Switches in the Aqueous Phase: Theory and Experiment

XUV photoelectron spectroscopy (XPS) is a powerful method for investigating the electronic structures of molecules. However, the correct interpretation of results in the condensed phase requires theoretical models that account for solvation. Here we present experimental aqueous-phase XPS of two organic biomimetic molecular switches, NAIP and p-HDIOP. These switches are structurally similar, but have opposite charges and thus present a stringent benchmark for solvation models which need to reproduce the observed ΔeBE = 1.1 eV difference in electron binding energy compared to the 8 eV difference predicted in the gas phase. We present calculations using implicit and explicit solvent models. The latter employs the average solvent electrostatic configuration and free energy gradient (ASEC-FEG) approach. Both nonequilibrium polarizable continuum models and ASEC-FEG calculations give vertical binding energies in good agreement with the experiment for three different computational protocols. Counterions, explicitly accounted for in ASEC-FEG, contribute to the stabilization of molecular states and reduction of ΔeBE upon solvation.

Analyzing Nonequilibrium Quantum States through Snapshots with Artificial Neural Networks

Current quantum simulation experiments are starting to explore nonequilibrium many-body dynamics in previously inaccessible regimes in terms of system sizes and timescales. Therefore, the question emerges as to which observables are best suited to study the dynamics in such quantum many-body systems. Using machine learning techniques, we investigate the dynamics and, in particular, the thermalization behavior of an interacting quantum system that undergoes a nonequilibrium phase transition from an ergodic to a many-body localized phase. We employ supervised and unsupervised training methods to distinguish nonequilibrium from equilibrium data, using the network performance as a probe for the thermalization behavior of the system. We test our methods with experimental snapshots of ultracold atoms taken with a quantum gas microscope. Our results provide a path to analyze highly entangled large-scale quantum states for system sizes where numerical calculations of conventional observables become challenging.

Effect of point mutations on the ultrafast photo-isomerization of Anabaena sensory rhodopsin

Anabaena sensory rhodopsin (ASR) is a particular microbial retinal protein for which light-adaptation leads to the ability to bind both the all-trans, 15-anti (AT) and the 13-cis, 15-syn (13C) isomers of the protonated Schiff base of retinal (PSBR). In the context of obtaining insight into the mechanisms by which retinal proteins catalyse the PSBR photo-isomerization reaction, ASR is a model system allowing to study, within the same protein, the protein-PSBR interactions for two different PSBR conformers at the same time. A detailed analysis of the vibrational spectra of AT and 13C, and their photo-products in wild-type ASR obtained through femtosecond (pump-) four-wave-mixing is reported for the first time, and compared to bacterio- and channelrhodopsin. As part of an extensive study of ASR mutants with blue-shifted absorption spectra, we present here a detailed computational analysis of the origin of the mutation-induced blue-shift of the absorption spectra, and identify electrostatic interactions as dominating steric effects that would entail a red-shift. The excited state lifetimes and isomerization reaction times (IRT) for the three mutants V112N, W76F, and L83Q are studied experimentally by femtosecond broadband transient absorption spectroscopy. Interestingly, in all three mutants, isomerization is accelerated for AT with respect to wild-type ASR, and this the more, the shorter the wavelength of maximum absorption. On the contrary, the 13C photo-reaction is slightly slowed down, leading to an inversion of the ESLs of AT and 13C, with respect to wt-ASR, in the blue-most absorbing mutant L83Q. Possible mechanisms for these mutation effects, and their steric and electrostatic origins are discussed.

Interferometric determination of the s and d-wave scattering amplitudes in 87Rb

We demonstrate an interference method to determine the low-energy elastic scattering amplitudes of a quantum gas. We linearly accelerate two ultracold atomic clouds up to energies of 1.2 mK and observe the collision halo by direct imaging in free space. From the interference between s- and d- partial waves in the differential scattering pattern we extract the corresponding phase shifts. The method does not require knowledge of the atomic density. This allows us to infer accurate values for the s- and d-wave scattering amplitudes from the zero-energy limit up to the first Ramsauer minimum using only the van der Waals C6 coefficient as theoretical input. For the 87Rb triplet potential, the method reproduces the scattering length with an accuracy of 6%.

Giant helium dimers produced by photoassociation of ultracold metastable atoms

We produce giant, purely long-range helium dimers by photoassociation of metastable helium atoms in a magnetically trapped, ultracold cloud. The photoassociation laser is detuned close to the atomic 2(3)S1-2(3)P0 line and produces strong heating of the sample when resonant with molecular bound states. The temperature of the cloud serves as an indicator of the molecular spectrum. We report good agreement between our spectroscopic measurements and our calculations of the five bound states belonging to a 0(+)(u) purely long-range potential well. These previously unobserved states have classical inner turning points of about 150a(0) and outer turning points as large as 1150a(0).

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La thèse de J. Léonard sur les médecins de l'Ouest au xixe siècle confirme une évolution déjà sensible depuis quelques années des sujets de thèse d'histoire sociale. Les auteurs délaissent de plus en plus le découpage régional ou départemental au profit d'un découpage professionnel ou catégoriel. L'auteur n'a pas cru pouvoir cependant s'affranchir totalement du cadre régional. L'introduction (p. 2) explique pourquoi. Le premier sujet, déposé en décembre 1959, avait pour intitulé « Les médecins dans la vie française'au xixe siècle ». Le second intitulé (en 1968) s'est restreint à l'Ouest, par suite de l'immensité de l'ignorance sur le thème et du désir légitime de J. Léonard de présenter une analyse concrète et non purement statistique d'un groupe de médecins enracinés localement.

Bose-Einstein condensation of metastable helium

We have observed a Bose-Einstein condensate in a dilute gas of 4He in the (3)2S(1) metastable state. We find a critical temperature of (4.7+/-0.5) microK and a typical number of atoms at the threshold of 8 x 10(6). The maximum number of atoms in our condensate is about 5 x 10(5). An approximate value for the scattering length a = (16+/-8) nm is measured. The mean elastic collision rate at threshold is then estimated to be about 2 x 10(4) s(-1), indicating that we are deeply in the hydrodynamic regime. The typical decay time of the condensate is 2 s, which places an upper bound on the rate constants for two-body and three-body inelastic collisions.

Short-term changes in neck muscle and eye movement responses following unilateral vestibular neurectomy in the cat

The purpose of this study was to investigate changes in neck muscle and eye movement responses during the early stages of vestibular compensation (first 3 weeks after unilateral vestibular neurectomy, UVN). Electromyographic (EMG) activity from antagonist neck extensor (splenius capitis) and flexor (longus capitis) muscles and eye movements were recorded during sinusoidal visual and/or otolith vertical linear stimulations in the 0.05-1 Hz frequency range (corresponding acceleration range 0.003-1.16 g) in the head-fixed alert cat. Preoperative EMG activity from the splenius and longus capitis muscles showed a pattern of alternate activation of the antagonist neck muscles in all the cats. After UVN, two motor strategies were observed. For three of the seven cats, the temporal activation of the individual neck muscles was the same as that recorded before UVN. For the other four cats, UVN resulted in a pattern of coactivation of the flexor and extensor neck muscles because of a phase change of the splenius capitis. In both subgroups, the response patterns of the antagonist neck muscles were consistent for each cat independently of the experimental conditions, throughout the 3 weeks of testing. Cats displaying alternate activation of antagonist neck muscles showed an enhanced gain of the visually induced neck responses, particularly in the high range of stimulus frequency, and a gain decrease in the otolith-induced neck responses at the lowest frequency (0.25 Hz) only. By contrast, for cats with neck muscle coactivation, the gain of the visually induced neck responses was basically unaffected relative to preoperative values, whereas otolith-induced neck responses were considerably decreased in the whole range of stimulation. As concerns oculomotor responses, results in the two subgroups of cats were similar. The optokinetic responses were not affected by the vestibular lesion. On the contrary, otolith-induced eye responses showed a gain reduction and a phase lead. Deficits and short-term changes after UVN of otolith- and semicircular canal-evoked collic and ocular responses are compared.

[Myocardial revascularization using Vineberg's procedure; 23 years follow-up]

The authors report the case of a patient followed up for 23 years after a double myocardial implantation of the internal mammary arteries (Vineberg technique) for unstable angina. The result of this procedure of surgical revascularisation has been very satisfactory to date. The authors believe this to be the longest follow-up reported in the medical literature.

[Medical interruption of pregnancy. Indications and techniques. Critical study and reflections on 324 cases]

A retrospective study of 324 cases highlights the difficulties encountered in identifying indications for medical pregnancy terminations (MPTs) which are permitted by French law and medically justified. In addition, the ethical problems raised do not facilitate the decision to opt for a MPT, which must be made by a multi-disciplinary committee. The methods used to evaluate the pregnancy are largely surgical during the first three months, and these are succeeded during the next six months by medical methods involving the use of synthetic prostaglandins. The complications which may occur are far from minor. The various protocols used by the authors are described together with their results and complications.

[Value of ultrasonics in acute pelvic infections]

Sonograms performed in 228 women admitted for acute pelvic infection has enabled to find a normal image in 39.9% of the cases. In order of frequency, the abnormalities include: endometrial alterations (31.1%), one (or several) pelvic masses (25.9%) and a collection in the Douglas cul-de-sac (22.8%). The main advantage of the examination in the acute phase is the diagnosis and the study of the mass structure: most of the time, it concerns a "mixed" or heterogeneous aspect, for all of the images of a mass, as well as for images corresponding to a tubo-adnexal collection. The major critic of this examination is the lack of specificity of the images which are very diversified. The risk of confusion with another pathology (gynecological or, exceptionally gastro-intestinal) must be decreased with an examination of good quality and comparison with the clinical context. The presumption of a tubo-adnexal collection cannot, in most cases, be established with certainty. However, the Echography guides the diagnosis by showing an anechogenous image or a particular aspect (Douglas abscess, huge septated images of sequelae) and remains more reliable than clinic to detect the mass (44% of false negative, clinically) and follow the evolution of the disease. The therapeutic advantage is also mentioned, but the tap of an abscess under sonogram guidance is seldom performed.