Dynamic interface velocity for junction characterization

A dynamic velocity at the n-p junction interface has been introduced. Solar cell structures have been used as diode models. The relationship of the dynamic velocity with the technological parameters of solar cells and with the junction operating conditions has been considered. The variations of this dynamic velocity with the potential at the junction point out the influence of the base doping level and of the base width, and allow to differentiate the nature of the cell back contact.     

Immune parameters affecting adenoviral vector gene therapy in the brain

Gene therapy utilizing replication deficient adenoviral vectors represents a potentially promising approach to the treatment of brain tumors. Limited duration of systemic transgene expression and inefficient transduction following repeat systemic vector administration secondary to an effective anti-vector immune response limits the potential application of first generation adenoviral vectors. Whether host immune responses will significantly limit the use of these vectors within the immunopriviledged environment of the central nervous system remains to be elucidated. Following a single intravenous injection of a beta-galactosidase expressing adenoviral vector (Ad.CMV-betagal), we found maximal betagal transgene expression in systemic sites (i.e. liver) at day 4, with almost complete disappearance by day 7. In contrast, significant beta-galactosidase activity was seen for greater than 28 days following a single intracerebral inoculum of virus. Rechallenge experiments demonstrated complete protection against repeat systemic vector administration, whereas intracerebral transgene expression was not affected by prior systemic or intracerebral exposure to adenoviruses. These data suggest that systemic anti-adenoviral vector immune responses are attenuated within the central nervous system and may not pose as significant a problem for the treatment of brain tumors as for other systemic indications.     

Serial neuropsychological assessment and magnetic resonance imaging analysis in multiple sclerosis

OBJECTIVE: To assess the correlation between cognitive dysfunction and disease burden in multiple sclerosis (MS) during a 1-year period. DESIGN: The Brief, Repeatable Battery of Neuropsychological Tests in Multiple Sclerosis was performed at entrance and 1 year. Patients underwent at least 20 proton density (range, 20-24) and T2-weighted axial magnetic resonance imaging (MRI) brain scans except for stable patients who were scanned monthly. Magnetic resonance imaging was evaluated using computer-automated, 3-dimensional volumetric analysis. SETTING: A research clinic of a university hospital. PATIENTS: Forty-four patients with MS of the following disease categories: relapsing-remitting (14), relapsing-remitting progressive (12), chronic progressive (13), and stable (5). MAIN OUTCOME MEASURES: The relationships between scores on the Brief, Repeatable Battery of Neuropsychological Tests in Multiple Sclerosis and 2 MRI measures (total lesion volume and brain to intracranial cavity volume ratio) were assessed using linear regression. These MRI measures were also compared with cognitive status at 1 year using analysis of variance. RESULTS: Overall, there was no decline in mean cognitive test performance during 1 year. Significant correlations were found between baseline neuropsychological test scores of nonverbal memory, information-processing speed, and attention and both MRI measures. Patients with chronic progressive MS demonstrated the strongest correlations. At 1 year, change in information-processing speed and attention correlated with change in total lesion volume. The mean increase in total lesion volume was 5.7 mL for 4 patients whose cognitive status worsened compared with 0.4 mL for 19 patients who improved and 0.5 mL for 21 patients who remained stable. CONCLUSIONS: During a 1-year period mean cognitive performance did not worsen. Automated volumetric MRI measures of total lesion volume and brain to intracranial cavity volume ratio correlated with neuropsychological performance, especially in patients with chronic progressive MS. Worsening MRI lesion burden correlated with cognitive decline.     

Adenosine mediates sustained adrenergic desensitization in the rat heart via activation of protein kinase C

Adenosine attenuates the myocardial metabolic and contractile responses induced by ss-adrenergic stimulation. Our study was conducted to investigate the longevity of this antiadrenergic action after adenosine exposure. Adenosine (33 micromol/L) was infused into isolated perfused rat hearts for 1, 5, 30, or 60 minutes, and the adrenergic responsiveness (AR) to isoproterenol (10(-8) mol/L) was determined at the end of each infusion period and during a 45-minute adenosine washout period. Interstitial levels of adenosine, as determined from epicardial surface transudates, returned to preinfusion levels within 10 minutes of washout. The duration of adenosine infusion had no effect on the extent of attenuation of AR at the end of the infusion. Whereas AR returned to preadenosine levels with washout of shorter adenosine infusions (1 and 5 minutes), there was a slow and incomplete recovery of AR after the longer exposures (30 and 60 minutes) to adenosine. The magnitude of this persistent antiadrenergic effect (PAE) of adenosine at 15 minutes of washout was proportional to the epicardial concentration of adenosine during infusion of the nucleoside. Infusion of adenosine either with the nonselective adenosine receptor antagonist 8-p-sulfophenyl theophylline or with the selective A1-receptor antagonist 1,3-dipropyl, 8-cyclopentylxanthine, abolished the PAE during the washout period. In addition, the PAE could be demonstrated only with the selective A1-receptor agonist 2-chloro-N6-cyclopentyladenosine and not with the selective A3-receptor agonist 4-aminobenzyl-5'-N methylcarboxamido-adenosine. When the protein kinase C (PKC) inhibitor chelerythrine was coadministered with adenosine, the PAE of adenosine was not apparent during adenosine washout. A 30-minute infusion of phenylephrine, an alpha-adrenergic agonist that enhances PKC activity, produced a PAE that lasted for up to 30 minutes of washout. This effect was prevented by the coinfusion of chelerythrine. Thus, it is concluded that the PAE of adenosine is determined by the myocardial concentration of this nucleoside and is manifested when myocardial concentrations of adenosine returned to baseline levels. Moreover, a 5-minute duration of adenosine exposure is required for the expression of the PAE. This latter effect seems to be dependent on adenosine-induced PKC activation via A1-receptors.     

Analysis of the dual discrimination ability of the two-port photorefractive joint transform correlator

An all-optical joint transform correlator featuring two operative correlation planes(ports) with complementary performance is presented. We present the theory of operation, derive the input-output characteristics, and demonstrate computer simulations and experimental results. The two-port joint transform correlator is based on simultaneous use of two photorefractive wave-mixing architectures. The first port uses two-beam coupling, and the second port uses four-wave mixing. The performance of the two ports depends on an experimentally controlled beam intensity ratio and the photorefractive coupling coefficient. With appropriate selection of these parameters, the first port is capable of high discrimination, while simultaneously the second offers a low discrimination output. Our results show that the two-beam coupling port can achieve peak-to-noise and signal-to-noise ratio values better than the phase-only correlator, whereas the four-wave-mixing port performs similarly to the classical joint transform correlator. This leads to a potential application in which the correlator could be set up so that in one port a general class is detected (interclass) and, in the other, the specific item in a class is detected (intraclass).     

On the fractal dimension of isosurfaces

A (3D) scalar grid is a regular n1 x n2 x n3 grid of vertices where each vertex v is associated with some scalar value sv. Applying trilinear interpolation, the scalar grid determines a scalar function g where g(v) = sv for each grid vertex v. An isosurface with isovalue σ is a triangular mesh which approximates the level set g(-1)(σ). The fractal dimension of an isosurface represents the growth ;in the isosurface as the number of grid cubes increases. We define and discuss the fractal isosurface dimension. Plotting the fractal ;dimension as a function of the isovalues in a data set provides information about the isosurfaces determined by the data set. We present statistics on the average fractal dimension of 60 publicly available benchmark data sets. We also show the fractal dimension is highly correlated with topological noise in the benchmark data sets, measuring the topological noise by the number of connected components in the isosurface. Lastly, we present a formula predicting the fractal dimension as a function of noise and validate the formula with experimental results.     

The gut‐kidney axis in chronic renal failure: A new potential target for therapy

Evidence is accumulating to consider the gut microbiome as a central player in the gut‐kidney axis. Microbiome products, such as advanced glycation end products, phenols, and indoles, are absorbed into the circulation but are cleared by normal‐functioning kidneys. These products then become toxic and contribute to the uremic load and to the progression of chronic kidney failure. In this review, we discuss the gut‐kidney interaction under the state of chronic kidney failure as well as the potential mechanisms by which a change in the gut flora (termed gut dysbiosis) in chronic kidney disease (CKD) exacerbates uremia and leads to further progression of CKD and inflammation. Finally, the potential therapeutic interventions to target the gut microbiome in CKD are discussed.     

Photorefractive Deconvolution Techniques for Optical Differentiation of Images

Abstract

A photorefractive deconvolution process for optical differentiation of images is suggested. The problems associated with the intrinsic resolution capabilities of this technique, resulting from the reading process, application of external fields and the spontaneous excitation rate of the carriers are discussed. The potential of this scheme is illustrated by using two well known test functions.     

Regulation of Secondary Metabolism in the Penicillium Genus

Penicillium, one of the most common fungi occurring in a diverse range of habitats, has a worldwide distribution and a large economic impact on human health. Hundreds of the species belonging to this genus cause disastrous decay in food crops and are able to produce a varied range of secondary metabolites, from which we can distinguish harmful mycotoxins. Some Penicillium species are considered to be important producers of patulin and ochratoxin A, two well-known mycotoxins. The production of these mycotoxins and other secondary metabolites is controlled and regulated by different mechanisms. The aim of this review is to highlight the different levels of regulation of secondary metabolites in the Penicillium genus.