A restoration framework for ultrasonic tissue characterization

Ultrasonic tissue characterization has become an area of intensive research. This procedure generally relies on the analysis of the unprocessed echo signal. Because the ultrasound echo is degraded by the non-ideal system point spread function, a deconvolution step could be employed to provide an estimate of the tissue response that could then be exploited for a more accurate characterization. In medical ultrasound, deconvolution is commonly used to increase diagnostic reliability of ultrasound images by improving their contrast and resolution. Most successful algorithms address deconvolution in a maximum a posteriori estimation framework; this typically leads to the solution of l(2)-norm or (1)-norm constrained optimization problems, depending on the choice of the prior distribution. Although these techniques are sufficient to obtain relevant image visual quality improvements, the obtained reflectivity estimates are, however, not appropriate for classification purposes. In this context, we introduce in this paper a maximum a posteriori deconvolution framework expressly derived to improve tissue characterization. The algorithm overcomes limitations associated with standard techniques by using a nonstandard prior model for the tissue response. We present an evaluation of the algorithm performance using both computer simulations and tissue-mimicking phantoms. These studies reveal increased accuracy in the characterization of media with different properties. A comparison with state-of-the-art Wiener and l(1)-norm deconvolution techniques attests to the superiority of the proposed algorithm.     

Establishment of a real-time PCR method for quantification of geosmin-producing Streptomyces spp. in recirculating aquaculture systems

Geosmin and 2-methylisoborneol (MIB) have been associated with off-flavour problems in fish and seafood products, generating a strong negative impact for aquaculture industries. Although most of the producers of geosmin and MIB have been identified as Streptomyces species or cyanobacteria, Streptomyces spp. are thought to be responsible for the synthesis of these compounds in indoor recirculating aquaculture systems (RAS). The detection of genes involved in the synthesis of geosmin and MIB can be a relevant indicator of the beginning of off-flavour events in RAS. Here, we report a real-time polymerase chain reaction (qPCR) protocol targeting geoA sequences that encode a germacradienol synthase involved in geosmin synthesis. New geoA-related sequences were retrieved from eleven geosmin-producing Actinomycete strains, among them two Streptomyces strains isolated from two RAS. Combined with geoA-related sequences available in gene databases, we designed primers and standards suitable for qPCR assays targeting mainly Streptomyces geoA. Using our qPCR protocol, we succeeded in measuring the level of geoA copies in sand filter and biofilters in two RAS. This study is the first to apply qPCR assays to detect and quantify the geosmin synthesis gene (geoA) in RAS. Quantification of geoA in RAS could permit the monitoring of the level of geosmin producers prior to the occurrence of geosmin production. This information will be most valuable for fish producers to manage further development of off-flavour events.     

Influence of temperature on the compaction of an organic powder and the mechanical strength of tablets

The purpose of this work consists in following the dependence of physical properties on the temperature during the compaction of an organic component. A special thermo-regulated die has been developed to realize uniaxial compression at different constant temperatures. This study has shown that a temperature change modifies the microstructures and the mechanical behaviour of the tablets. The measurement of the tablet porosity during the compression cycle allows us to conclude that temperature influences mainly the phenomena occurring during the isobaric stage of the compression cycle and not the ones during the pressure increase. On the other hand, during the pressure increase, the acoustical activity of the powder is reduced when temperature increases. The tensile strength of tablets realized at different temperatures was also studied and shows a maximum around 60 °C that can be explained by the SEM analysis of the microstructure of the tablets.     

Parents' ethnic-racial socialization practices: A review of research and directions for future study.

Recently, there has been an emergence of literature on the mechanisms through which parents transmit information, values, and perspectives about ethnicity and race to their children, commonly referred to as racial or ethnic socialization. This literature has sought to document the nature of such socialization, its antecedents in parents' and children's characteristics and experiences, and its consequences for children's well-being and development. In this article, the authors integrate and synthesize what is known about racial and ethnic socialization on the basis of current empirical research, examining studies concerning its nature and frequency; its child, parent, and ecological predictors; and its consequences for children's development, including ethnic identity, self-esteem, coping with discrimination, academic achievement, and psychosocial well-being. The authors also discuss conceptual and methodological limitations of the literature and suggest directions for future research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comments On "an Asymptotic Modal Observer For Linear Autonomous Time Lag Systems"

It is show that the proof of theorem 1 in the original paper of J. Leyva-Ramos and A.E. Pearson (ibid., vol. 40, p. 1291-4, 1995) is incomplete and that the state observer scheme results in steady-state error. Alternatively, a memoryless state observer for linear time-delay systems is provided. The original authors acknowledge that the criticism is correct, and suggest an alternative way of overcoming the problem     

Effect of Capacitor-Switching Surges on Insulation Aging and Incipient-Fault Breakdown of Distribution Cables and Accessories

This paper summarizes the finding related to the experimental evaluation of the effect of ringing switching surges on insulation aging and incipient-fault breakdown of distribution cables and accessories (CEA contract 092 D 234). The main emphasis in the present study was to reproduce test conditions as close as possible to the stresses observed in real distribution systems. This was done by first conducting extensive field recordings of capacitor-switching transients. The data obtained was used to define the characteristics of the test voltage to be reproduced in laboratory tests.     

Continuous versus intermittent bladder irrigation of amphotericin B for the treatment of candiduria

PURPOSE: The efficacy of continuous versus intermittent bladder irrigation with amphotericin B in the treatment of candiduria was compared. MATERIALS AND METHODS: A prospective, randomized and comparative pilot study was done on 20 patients. Continuous bladder irrigation with 50 mg./l. amphotericin B infused during 24 hours for 2 days was compared to 3 intermittent bladder irrigations of 10 mg./100 ml. amphotericin B in 1 day. Urine cultures were obtained 72 hours after treatment. RESULTS: The organism was eradicated in 8 patients (80%) who received continuous irrigation and 3 (30%) who received intermittent irrigation (p = 0.035). CONCLUSIONS: Continuous amphotericin B bladder irrigation was superior in terms of efficacy, ease of administration and patient comfort.     

Large Charged Drop Levitation Against Gravity

A hybrid electrostatic-acoustic levitator that can levitate and manipulate a large liquid drop in one gravity is presented. To the authors' knowledge, this is the first time such large drops (up to 4 mm in diameter in the case of water) have been levitated against 1-gravity. This makes possible, for the first time, many new experiments both in space and in ground-based laboratories, such as 1) supercooling and superheating, 2) containerless crystal growth from various salt solutions or melts, 3) drop dynamics of oscillating or rotating liquid drops, 4) drop evaporation and Rayleigh bursting, and 5) containerless material processing in space. The digital control system, liquid drop launch process, principles of electrode design, and design of a multipurpose room temperature levitation chamber are described. Preliminary results that demonstrate drop oscillation and rotation, and crystal growth from supersaturated salt solutions are presented.