A massive, cooling-flow-induced starburst in the core of a luminous cluster of galaxies.

In the cores of some clusters of galaxies the hot intracluster plasma is dense enough that it should cool radiatively in the cluster's lifetime, leading to continuous 'cooling flows' of gas sinking towards the cluster centre, yet no such cooling flow has been observed. The low observed star-formation rates and cool gas masses for these 'cool-core' clusters suggest that much of the cooling must be offset by feedback to prevent the formation of a runaway cooling flow. Here we report X-ray, optical and infrared observations of the galaxy cluster SPT-CLJ2344-4243 (ref. 11) at redshift z = 0.596. These observations reveal an exceptionally luminous (8.2 × 10(45) erg s(-1)) galaxy cluster that hosts an extremely strong cooling flow (around 3,820 solar masses a year). Further, the central galaxy in this cluster appears to be experiencing a massive starburst (formation of around 740 solar masses a year), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool-core clusters may not yet be fully established in SPT-CLJ2344-4243. This large star-formation rate implies that a significant fraction of the stars in the central galaxy of this cluster may form through accretion of the intracluster medium, rather than (as is currently thought) assembling entirely via mergers.

Three-dimensional electrode arrays for retinal prostheses: modeling, geometry optimization and experimental validation.

Three-dimensional electrode geometries were proposed to increase the spatial resolution in retinal prostheses aiming at restoring vision in blind patients. We report here the results from a study in which finite-element modeling was used to design and optimize three-dimensional electrode geometries. Proposed implants exhibit an array of well-like shapes containing stimulating electrodes at their bottom, while the common return grid electrode surrounds each well on the implant top surface. Extending stimulating electrodes and/or the grid return electrode on the walls of the cavities was also considered. The goal of the optimization was to find model parameters that maximize the focalization of electrical stimulation, and therefore the spatial resolution of the electrode array. The results showed that electrode geometries with a well depth of 30 µm yield a tenfold increase in selectivity compared to the planar structures of similar electrode dimensions. Electrode array prototypes were microfabricated and implanted in dystrophic rats to determine if the tissue would behave as hypothesized in the model. Histological examination showed that retinal bipolar cells integrate the electrode well, creating isolated cell clusters. The modeling analysis showed that the stimulation current is confounded within the electrode well, leading to selective electrical stimulation of the individual bipolar cell clusters and thereby to electrode arrays with higher spatial resolution.

[A traditional anesthesia consultation or a "telephone interview" within the framework of ambulatory surgery?]. / Consultation d'anesthésie traditionnelle ou "interview téléphonique" dans le cadre de la chirurgie ambulatoire?

UNLABELLED: Preoperative assessment for anaesthesia must detect in the setting of ambulatory surgery both medical and sociopsychologic problems which may contraindicate the ambulatory aspect of the procedure. The goal of our prospective study was to assess the efficacy of a preoperative telephone interview in screening the medical and sociopsychologic problems of ambulatory patients. 1,000 consenting consecutive outpatients participated to the study and were randomly allocated to one of two groups: patients in the standard group (STD) had a consultation a few days before surgery whereas those in the telephonic group (TEL) called the anesthetist a few days before, the physical exam being performed on the day of surgery. The cancellation of the ambulatory procedure was decided upon either medical criterias (MC) or sociopsychologic criterias (from Waetchler). RESULTS: both groups were comparable regarding SPC and MC but prescription of preoperative tests was more frequent in the STD group (result statistically significant). In conclusion, this new approach is as reliable as the standard consultation in screening the SPC which remain the most frequent cause of cancellation in ambulatory surgery. Therefore this telephonic interview which is simple and reliable for screening outpatients may represent a suitable alternative to a standard consultation.