Experimental determination of photon propagation in highly absorbing and scattering media

Optical imaging and tomography in tissues can facilitate the quantitative study of several important chromophores and fluorophores. Several theoretical models have been validated for diffuse photon propagation in highly scattering and low-absorbing media that describe the optical appearance of tissues in the near-infrared (NIR) region. However, these models are not generally applicable to quantitative optical investigations in the visible because of the significantly higher tissue absorption in this spectral region compared with that in the NIR. We performed photon measurements through highly scattering and absorbing media for ratios of the absorption coefficient to the reduced scattering coefficient ranging approximately from zero to one. We examined experimentally the performance of the absorption-dependent diffusion coefficient defined by Aronson and Corngold [J. Opt. Soc. Am. A 16, 1066 (1999)] for quantitative estimations of photon propagation in the low- and high-absorption regimes. Through steady-state measurements we verified that the transmitted intensity is well described by the diffusion equation by considering a modified diffusion coefficient with a nonlinear dependence on the absorption. This study confirms that simple analytical solutions based on the diffusion approximation are suitable even for high-absorption regimes and shows that diffusion-approximation-based models are valid for quantitative measurements and tomographic imaging of tissues in the visible.     

Development and Biological Evaluation of a Novel Aurora A Kinase Inhibitor

Stop dividing : In the quest for antitumorigenic compounds, aurora A kinase has recently emerged as a potential drug target. In this paper three novel aurora inhibitors (shown in the illustration) have been tested for their biological activity in cultured cells. One of them (TC‐28) appears to be a promising specific aurora A inhibitor in vivo.

     

Sectoral linkages and industrial efficiency: a dilemma or a requisition in identifying development priorities?

This paper attempts to provide an empirical evaluation of the potential relationship between sectoral linkages (backward and forward) and technical efficiency using the 1995 input–output tables for 14 EU countries. Sectoral technical efficiency is obtained by the econometric estimation of a “multilateral” stochastic input distance function, while sectoral backward and forward linkage coefficients were computed using the noncomplete hypothetical extraction method suggested by Dietzenbacher and Van der Linden (J Reg Sci 37:235–257, 1997). The empirical results suggest that the relationship between industrial technical efficiency and sectoral interdependence is ambiguous. Although the majority of the countries, in the sample exhibit a negative relationship, for some countries, the opposite is revealed. This implies that policy makers should not be blindly based on sectoral interdependence in forming development plans, and they should take into consideration the efficiency of resource utilization of individual sectors. The combination of the information provided by both indices will assist in devising effective policy plans in stimulating internal economic growth.     

On the importance of the Vg,max-Vth parameter on LTPS TFT stressing behavior

In this work we point out the importance of the device parameter V_g,max-V_th (the difference between the gate voltage at maximum transconductance and the threshold voltage obtained from linear extrapolation method) for LTPS TFTs under dc stress. The evolution of this parameter with stress time is monitored for the first time, along with the other typical device parameters (V_th, G_m,max, S) in order to further clarify the nature of the traps generated. In the first dc stress case considered, we observed very different S degradation of the two samples, but very similar G_m,max degradation, as well as similar V_g,max-V_th evolution. Therefore, G_m,max evolution with stress time was found to be related more strongly to tail state generation, probed through V_g,max-V_th, and not to midgap trap generation, probed through S. In the second case, no midgap state generation is observed, but only severe tail state generation. Hence, the nature of the created defects and the reason for the significant G_m,max reduction could only be probed through the observation of V_g,max-V_th, a parameter not utilized until now. Finally, stressing both n- and p-channel devices, we are able to explain the much more intense G_m,max degradation observed for n-channel devices, associating it to the larger tail state generation in n-channel TFTs, also pointed by V_g,max-V_th evolution with stress.     

Multiple hypothesis tracking for data association in vehicular networks

The introduction of Vehicle to Vehicle (V2V) and Vehicle to Infrastructure (V2I) communications in Intelligent Transportation Systems of the future brings new opportunities and new challenges into the automotive scene. Vehicular communications broaden the information spectrum that is available to each vehicle, allowing the enhancement of existing applications and the introduction of new ones. Undoubtedly, the impact of this new technology in transportation safety, efficiency and infotainment is expected to be very important.A significant part of research in vehicular networks (VANETs) is dedicated to networking issues like routing and safety. However, perception systems which until now were based on onboard sensors only, need to incorporate the wirelessly received information in order to extend the situation awareness of the vehicle and the driver. This paper presents an algorithm for associating targets tracked from an onboard radar sensor with the position and motion data received from the VANET. The core of the algorithm is a track oriented multiple hypothesis tracker that is modified for incorporating information included in VANET messages. The algorithm is tested in real scenarios using two experimental vehicles and then compared with two other algorithmic approaches. One is using a simpler single hypothesis algorithm for association of VANET messages and the second is using only the onboard sensors for environment perception. As a result, the advantages of the Multiple Hypothesis Algorithm regarding association performance and the added value of wireless information in the perception system are highlighted.     

An Authentication Scheme for Ad-hoc Networks using Threshold Secret Sharing

Ad-hoc networks are peer-to-peer self- organized networks that make possible the communication between nodes located in areas, where communication infrastructure is absent or difficult to implement. For such networks, security is a crucial issue, since the wireless medium is vulnerable to various attacks. A centralized solution can be easily compromised, leaving the nodes exposed to threats originating from malicious users. In this paper, a security design for Ad-hoc networks is proposed and studied, providing authentication to the nodes that follow the principles of threshold secret sharing.     

Bayesian restoration using a new nonstationary edge-preserving image prior.

In this paper, we propose a class of image restoration algorithms based on the Bayesian approach and a new hierarchical spatially adaptive image prior. The proposed prior has the following two desirable features. First, it models the local image discontinuities in different directions with a model which is continuous valued. Thus, it preserves edges and generalizes the on/off (binary) line process idea used in previous image priors within the context of Markov random fields (MRFs). Second, it is Gaussian in nature and provides estimates that are easy to compute. Using this new hierarchical prior, two restoration algorithms are derived. The first is based on the maximum a posteriori principle and the second on the Bayesian methodology. Numerical experiments are presented that compare the proposed algorithms among themselves and with previous stationary and non stationary MRF-based with line process algorithms. These experiments demonstrate the advantages of the proposed prior.     

Power management adaptation techniques for video transmission over TFRC

In this paper, we describe power management adaptation techniques for wireless video transmission using the TCP Friendly Rate Control (TFRC) protocol that take into account feedback about the received video quality and try to intelligently adapt transmitting power accordingly. The purpose of the mechanisms is to utilize TFRC feedback and thus achieve a beneficial balance between power consumption and the received video quality. There are two power adaptation mechanisms proposed, each one with its own advantages. They both offer significant improvements when used in terms of both power consumption and received video quality. We use simulation in order to compare and evaluate our approach. Copyright © 2011 John Wiley & Sons, Ltd.