Role of insulin-like growth factor binding protein-3 in 1, 25-dihydroxyvitamin-d 3 -induced breast cancer cell apoptosis.

Insulin-like growth factor I (IGF-I) is implicated in breast cancer development and 1, 25-dihydroxyvitamin D3 (1, 25-D3) has been shown to attenuate prosurvival effects of IGF-I on breast cancer cells. In this study the role of IGF binding protein-3 (IGFBP-3) in 1, 25-D3-induced apoptosis was investigated using parental MCF-7 breast cancer cells and MCF-7/VD(R) cells, which are resistant to the growth inhibitory effects of 1, 25-D3. Treatment with 1, 25-D3 increased IGFBP-3 mRNA expression in both cell lines but increases in intracellular IGFBP-3 protein and its secretion were observed only in MCF-7. 1, 25-D3-induced apoptosis was not associated with activation of any caspase but PARP-1 cleavage was detected in parental cells. IGFBP-3 treatment alone produced cleavage of caspases 7, 8, and 9 and PARP-1 in MCF-7 cells. IGFBP-3 failed to activate caspases in MCF-7/VD(R) cells; however PARP-1 cleavage was detected. 1, 25-D3 treatment inhibited IGF-I/Akt survival signalling in MCF-7 but not in MCF-7/VD(R) cells. In contrast, IGFBP-3 treatment was effective in inhibiting IGF-I/Akt pathways in both breast cancer lines. These results suggest a role for IGFBP-3 in 1, 25-D3 apoptotic signalling and that impaired secretion of IGFBP-3 may be involved in acquired resistance to vitamin D in breast cancer

Dificultades de los estudiantes con el papel específico del campo eléctrico en la Óptica

This paper deals with the difficulties of the understanding of tlie specific role of the electric field in Optics among students enrolled in undergraduate physics courses. Wiener's experiment along with symmetry arguments provide the basis for an instructional strategy designed to address this specific difficulty

OPTICAL INVESTIGATION OF HIGH-FIELD CONDUCTION AND PREBREAKDOWN IN A DIELECTRIC LIQUID

International audienceLight emission studies of the high-field conduction and prebreakdown phenomena in a mixture of mono and dibenzyltoluene (M/DBT), used as polypropylene impregnant in the all-film capacitor technology, have been undertaken to gain insight into the underlying physical mechanisms responsible for these processes. The absorption spectrum of this fluid, in the UV region, shows the appearance of structured bands at 348, 366 and 386 nm indicating a luminescence process via anthracene and 9-methylanthracene impurities at a concentration of 3 x 10(-3) mol/l. Optical and electrical measurements were performed simultaneously on the electrically stressed fluid. Electroluminescence of the impurities contained in M/DBT has been investigated using a new uniform field electrode arrangement. The light inception stress was determined to be approximately 20 Vmum-1 for ac excitation (50 Hz). Configurations with different interfacial situations were studied and we have evidenced a correlation between charge injection and electroluminescence activity. Spectral analysis of the light radiated by streamers in M/DBT in a needle-plane electrode geometry, under step voltage (1 to 50 mus, 30 kV) revealed, for both polarities, the presence of H-2 and C2 characteristic bands emerging from a continuum corresponding to the dissociation and recombination of molecular fragments

Exploiting root-mean-square time-frequency structure for multiple-image optical compression and encryption

International audienceWe report on a new algorithm to compress and encrypt simultaneously multiple images (target images). This method, which is based upon a specific spectral multiplexing (fusion without overlapping) of the multiple images, aims to achieve a single encrypted image, at the output plane of our system, that contains all information needed to reconstruct the target images. For that purpose, we divide the Fourier plane of the image to transmit into two types of area, i.e., specific and common areas to each target image. A segmentation criterion taking into account the rootmean- square duration of each target image spectrum is proposed. This approach, which consists of merging the input target images together (in the Fourier plane) allows us to reduce the information to be stored and/or transmitted (compression) and induce noise on the output image (encryption). To achieve a good encryption level, a first key image (containing biometric information and providing the intellectual property of the target images) is used. A second encryption key is inserted in the Fourier plane to ensure a relevant phase distribution of the different merged spectra. We also discuss how the encoding information can be optimized by minimizing the number of bits required to encode each pixel. © 2010 Optical Society of Americ

Optical image compression and encryption methods

International audienceOver the years extensive studies have been carried out to apply coherent optics methods in real-time communications and image transmission. This is especially true when a large amount of information needs to be processed, e.g., in high-resolution imaging. The recent progress in data-processing networks and communication systems has considerably increased the capacity of information exchange. However, the transmitted data can be intercepted by nonauthorized people. This explains why considerable effort is being devoted at the current time to data encryption and secure transmission. In addition, only a small part of the overall information is really useful for many applications. Consequently, applications can tolerate information compression that requires important processing when the transmission bit rate is taken into account. To enable efficient and secure information exchange, it is often necessary to reduce the amount of transmitted information. In this context, much work has been undertaken using the principle of coherent optics filtering for selecting relevant information and encrypting it. Compression and encryption operations are often carried out separately, although they are strongly related and can influence each other. Optical processing methodologies, based on filtering, are described that are applicable to transmission and/or data storage. Finally, the advantages and limitations of a set of optical compression and encryption methods are discussed

A New Robust and Discriminating Method for Face Recognition Based on Correlation Technique and Independent Component Analysis Model

International audienceWe demonstrate a novel technique for face recognition combined the independent component analysis (ICA) model with the optical correlation technique. Our approach relies on the performances of a strongly discriminating optical correlation method along with the robustness of the ICA model. Simulations were performed to illustrate how this algorithm can identify a face with images from the Pointing Head Pose Image Database (PHPID). While maintaining algorithmic simplicity, this approach based on ICA representation significantly increases the true recognition rate compared to that obtained with an all numerical ICA identity recognition method, that we recently developed, and with another based on optical correlation and a standard composite filter

Quelques reflexions sur le concept d'entropie issues d'un enseignement de thermodynamique

The authors establish the existence of a gap between physics' students conceptions concerning the notion of entropy and Clausius's, Boltzmann's, constructors of this concept. They analyze some basic features at the origin of these conceptions and some characteristics of the common sense interpretation of entropy. They conclude by some didactical propositions

Understanding Correlation Techniques for Face Recognition: From Basics to Applications

International audienc

Optical Activities as Computing Resources for Space-time Symmetries

It is known that optical activities can perform rotations. It is shown that the rotation, if modulated by attenuations, can perform symmetry operations of Wigner's little group which dictates the internal space-time symmetries of elementary particles.Comment: 13 pages, to be published in J. Mod. Optic