Visuospatial ability factors and performance variables in laparoscopic simulator training

Visuospatial ability has been shown to be important to several aspects of laparoscopic performance, including simulator training. Only a limited subset of visuospatial ability factors however has been investigated in such studies. Tests for different visuospatial ability factors differ in stimulus complexity, in their emphasis on identifying visual stimuli in a cluttered context, and in the demands they make on speed of processing. To help clarify the involvement of visuospatial ability factors in laparoscopic performance the current study investigated the role of four such factors in laparoscopic simulator performance. Twenty four students participated in a two-month course, consisting of eight weekly, half-hour laparoscopic simulator training sessions. Before the start of this course four visuospatial ability factors were measured. Learning curves were based on the simulator performance variables of (task) Duration, Motion efficiency, and Damage. The visuospatial ability factor Visualization impacted Damage and Motion efficiency. The factor Spatial relations impacted Damage. Visuospatial ability factors measuring the ability to mentally manipulate complex to moderately complex stimuli are more important than other visuospatial ability factors during basic laparoscopic simulator training. A finding relevant to theories of skill development is that the impact of Visualization on learning curves for Damage and Motion efficiency was most evident during early- and late (but not middle) training, which may be an indicator of a switch between different phases of skills learning. Learning curves and repeated measures analyses indicated damage control should be emphasized in laparoscopic skills trainin

A far-infrared heterodyne sidebands spectrometer

We present recent experimental developments in far-infrared coherent spectroscopy. Most known far-infrared sidebands spectrometers use the direct detection scheme. The system developed at Lille operates in the heterodyne mode. This technique offers particular advantages when large detection instantaneous bandwidths are needed, as could be the case in time resolved spectroscopy. As a counterpart of a heavier electronic receiver system, the filtering constraints in the optical path are totally eliminated, leading to a potential lowering of the overall noise system. The receiver operates very close to physical limits. A carefully designed optical line, incorporating only reflective components, allows to keep optical losses at very low levels, on the whole operating range. By using particular laser injection coupling and power extraction schemes, reasonable short and long term stability has been achieved in sidebands power generation. Some spectroscopic results illustrating sensitivity and resolution capabilities are presented

Asymptotic and transient behaviour for a nonlocal problem arising in population genetics

International audienceThis work is devoted to the study of an integro-differential system of equations modelling the genetic adaptation of a pathogen by taking into account both mutation and selection processes. First we study the asymptotic behaviour of the system and prove that it eventually converges to a stationary state. Next we more closely investigate the behaviour of the system in the presence of multiple evolutionary attractors. Under suitable assumptions and based on a small mutation variance asymptotic, we describe the existence of a long transient regime during which the pathogen population remains far from its asymptotic behaviour and highly concentrated around some phenotypic value that is different from the one described by its asymptotic behaviour. In that setting, the time needed for the system to reach its large time configuration is very long and multiple evolutionary attractors may act as a barrier of evolution that can be very long to bypass

Analog microwave photonic link based on a high power directly modulated laser, a high power photodiode and passive impedance matching

International audienceWe report on the design and characterization of a high-power and high dynamic range directly modulated analog fiber optic link in the S (2-4 GHz) band. The link is amplifier free, and uses passive impedance matching networks associated to high power laser diode and high power photodiode. Thanks to the high components efficiencies, together with the benefit of reactive impedance matchings, we achieved a high gain (≥ 0 dB) over 500 MHz bandwidths. Moreover, the use of high power and high linearity components allowed us to achieve simultaneously an output -1dB compression point higher than 20 dBm, and an output third order intercept point (OIP3) of more than 31 dBm. The measured spurious free dynamic range is as high as 114 dB.Hz2/3

High resolution spectroscopy of six SOCl2 isotopologues from the microwave to the far-infrared

Despite its potential role as an atmospheric pollutant, thionyl chloride, SOCl2, remains poorly characterized in the gas phase. In this study, the pure rotational and ro-vibrational spectra of six isotopologues of this molecule, all detected in natural abundance, have been extensively studied from the cm-wave band to the far-infrared region by means of three complementary techniques: chirped-pulse Fourier transform microwave spectroscopy, sub-millimeter-wave spectroscopy using frequency multiplier chain, and synchrotron-based far-infrared spectroscopy. Owing to the complex line pattern which results from two nuclei with non-zero spins, new, high-level quantum-chemical calculations of the hyperfine structure played a crucial role in the spectroscopic analysis. From the combined experimental and theoretical work, an accurate semi-experimental equilibrium structure (rSEe ) of SOCl2 has been derived. With the present data, spectroscopy-based methods can now be applied with confidence to detect and monitor this species, either by remote sensing or in situ