Femtosecond spectral electric field reconstruction using coherent transients

We have implemented a new approach for measuring the time-dependent intensity and phase of ultrashort optical pulses. It is based on the interaction between shaped pulses and atoms, leading to coherent transients.Comment: 4 pages Accepted in Optics Letter

Depletion of SMN by RNA interference in HeLa cells induces defects in Cajal body formation

Neuronal degeneration in spinal muscular atrophy (SMA) is caused by reduced expression of the survival of motor neuron (SMN) protein. The SMN protein is ubiquitously expressed and is present both in the cytoplasm and in the nucleus where it localizes in Cajal bodies. The SMN complex plays an essential role for the biogenesis of spliceosomal U-snRNPs. In this article, we have used an RNA interference approach in order to analyse the effects of SMN depletion on snRNP assembly in HeLa cells. Although snRNP profiles are not perturbed in SMN-depleted cells, we found that SMN depletion gives rise to cytoplasmic accumulation of a GFP-SmB reporter protein. We also demonstrate that the SMN protein depletion induces defects in Cajal body formation with coilin being localized in multiple nuclear foci and in nucleolus instead of canonical Cajal bodies. Interestingly, the coilin containing foci do not contain snRNPs but appear to co-localize with U85 scaRNA. Because Cajal bodies represent the location in which snRNPs undergo 2′-O-methylation and pseudouridylation, our results raise the possibility that SMN depletion might give rise to a defect in the snRNA modification process

Development of a three-dimensional model of a vertical-axis and transverse-flow hydrokinetic turbine

Water Qualit

Factorization of Numbers with the temporal Talbot effect: Optical implementation by a sequence of shaped ultrashort pulses

We report on the successful operation of an analogue computer designed to factor numbers. Our device relies solely on the interference of classical light and brings together the field of ultrashort laser pulses with number theory. Indeed, the frequency component of the electric field corresponding to a sequence of appropriately shaped femtosecond pulses is determined by a Gauss sum which allows us to find the factors of a number

Biomechanical behaviour of human bile duct wall and impact of cadaveric preservation processes.

International audienceBiliary diseases are the third most common cause of surgical digestive disease. There is a close relationship between the mechanical performance of the bile duct and its physiological function. Data of biomechanical properties of human main bile duct are scarce in literature. Furthermore, mechanical properties of soft tissues are affected by these preservation procedures. The aim of the present work was, on the one hand, to observe the microstructure of the human bile duct by means of histological analysis, on the other hand, to characterize the mechanical behavior and describe the impact of different preservation processes. A mechanical study in a controlled environment consisting of cyclic tests was made. The results of the mechanical tests are discussed and explained using the micro-structural observations. The results show an influence of the loading direction, which is representative of an anisotropic behavior. A strong hysteresis due to the viscoelastic properties of soft tissues was also observed. Embalming and freezing preservation methods had an impact on the biomechanical properties of human main bile duct, with fiber network deterioration. That may further provide a useful quantitative baseline for anatomical and surgical training using embalming and freezing

Animal experimentation in oncology and radiobiology: Arguments for and against following a critical literature review

Despite the international 3Rs principles that recommends replacing, reducing and refining the use of animals in medical experimentation, it remains difficult to obtain funding in Canada for medical research that respects these principles, particularly with regard to replacement. This observation led our team to review the literature on the arguments for and against animal experimentation in the fields of oncology and radiobiology. This article presents a synthesis of these arguments. Using the method created by McCullough and colleagues to conduct critical reviews of the ethics literature, we analysed 25 texts discussing the arguments for and against animal experimentation in oncology and radiobiology. Six broad categories of arguments for animal experimentation and eleven categories of arguments against it emerged from our analyses. Furthermore, the arguments against animal testing are more convincing from both an empirical and normative perspective. Also, most arguments obtained are transferable in other fields of medicine. In addition to the literature review, a critical reflection was conducted and other arguments were discussed. It seems that a conservative culture persists in medical research, despite the scientific evidence and ethical arguments to the contrary. Malgré les principes internationaux des 3R qui recommande de remplacer, réduire et raffiner l’utilisation des animaux dans l’expérimentation médicale, il reste difficile d’obtenir au Canada le financement de recherches médicales qui respectent ces principes, notamment en ce qui concerne le remplacement. Ce constat a amené notre équipe à faire une revue de la littérature sur les arguments pour et contre l’expérimentation animale dans les domaines de l’oncologie et de la radiobiologie. Cet article présente une synthèse de ces arguments. En utilisant la méthode créée par McCullough et collègues pour réaliser des revues critiques de la littérature en éthique, nous avons analysé 25 écrits discutant des arguments pour et contre l’expérimentation animale en oncologie et en radiobiologie. Six grandes catégories d’arguments en faveur de l’expérimentation animale et onze catégories d’arguments contre celle-ci sont ressorties de nos analyses. En outre, les arguments contre l’expérimentation animale sont plus convaincants d’un point de vue empirique et normatif. De plus, la plupart des arguments obtenus sont transférables dans d’autres domaines de la médecine. En plus de l’analyse documentaire, une réflexion critique a été menée et d’autres arguments ont été discutés. Il semble qu’une culture conservatrice persiste dans la recherche médicale, malgré les preuves scientifiques et les arguments éthiques contraires

Time-dependent photoionization of azulene: Optically induced anisotropy on the femtosecond scale

We measure the photoionization cross-section of vibrationally excited levels in the S2 state of azulene by femtosecond pump-probe spectroscopy. At the wavelengths studied (349-265 nm in the pump) the transient signals exhibit two distinct and well-defined behaviours: (i) Short-term (on the order of a picosecond) polarization dependent transients and (ii) longer (10 ps - 1 ns) time-scale decays. This letter focuses on the short time transient. In contrast to an earlier study by Diau et al.22 [J. Chem. Phys. 110 (1999) 9785.] we unambiguously assign the fast initial decay signal to rotational dephasing of the initial alignment created by the pump transition.Comment: Chemical Physics Letters (2008