Mutual information-based analysis of JPEG2000 contexts.

Context-based arithmetic coding has been widely adopted in image and video compression and is a key component of the new JPEG2000 image compression standard. In this paper, the contexts used in JPEG2000 are analyzed using the mutual information, which is closely related to the compression performance. We first show that, when combining the contexts, the mutual information between the contexts and the encoded data will decrease unless the conditional probability distributions of the combined contexts are the same. Given I, the initial number of contexts, and F, the final desired number of contexts, there are S(I, F) possible context classification schemes where S(I, F) is called the Stirling number of the second kind. The optimal classification scheme is the one that gives the maximum mutual information. Instead of using an exhaustive search, the optimal classification scheme can be obtained through a modified generalized Lloyd algorithm with the relative entropy as the distortion metric. For binary arithmetic coding, the search complexity can be reduced by using dynamic programming. Our experimental results show that the JPEG2000 contexts capture the correlations among the wavelet coefficients very well. At the same time, the number of contexts used as part of the standard can be reduced without loss in the coding performance.     

Dependence of attenuation in a vegetation canopy on frequency andplant water content

Theory is presented to provide insight into the observation that attenuation through vegetation is proportional to vegetation water content. In this analysis, the canopy is modeled as a sparse layer of randomly oriented particles (leaves, stalks, etc.) over a flat, homogeneous ground plane (soil) and an expression is obtained for the “optical depth”. The formulas developed by Ulaby and El Rayes are used to relate this expression to the water content of the canopy. In the low frequency extreme (Rayleigh scatterers), the attenuation varies almost linearly with water content and inversely with wavelength. In contrast, in the high frequency limit, the attenuation is independent of both water content and frequency, in between, geometry dependent “resonances” occur even at the low frequency end of the microwave spectrum (e.g. L-band) making the dependence of attenuation on frequency and water content specific to canopy architecture     

Evaluation of Handheld Radionuclide Identifiers

Characterization of commercially available instruments for measurement and identification of unknown radionuclides was carried out in support of the development and testing of the American National Standards Institute (ANSI) standard, N42.34, “Performance Criteria for Hand-held Instruments for the Detection and Identification of Radionuclides.” Measurements were based on the performance of the devices, i.e., the capability of the detectors to ensure a correct radionuclide identification in a given time interval for various radioactive sources.     

In-situ monitoring and control for MOCVD growth of AlGaAs and InGaAs

We have used spectroscopic ellipsometry to perform real-time monitoring during metalorganic chemical vapor deposition growth of AlGaAs (on GaAs) and InGaAs (on GaAs and InP). Optical constants for these materials were obtained up to growth temperatures of 600 to 700°C. This information permits real-time extraction of composition and layer thickness from the raw ellipsometric data at sample rates on the order of 0.5 Hz. We describe closed-loop control of composition and total layer thickness on AlGaAs-based structures, including Bragg reflectors. In-situ data obtained on double-heterostructure quantum-well laser structures demonstrate that spectroscopic ellipsometry is an extremely powerful monitoring and quality-control tool, giving important real-time information on complex structures that would be difficult and time-consuming to obtain after growth.     

Capillarovenous angioma of the maxillary sinus. Apropos of a case with review of the literature

Metabolic side-effects of antihypertensive drugs may increase the risk of coronary heart disease despite an adequate blood pressure reduction. Since combinations of different antihypertensive drugs are often necessary and frequently used, we performed a randomized study comparing the effects of a fixed combination of hydrochlorothiazide and sotalol (group A), or hydrochlorothiazide and captopril (group B) on blood pressure and on lipid and glucose metabolism in 40 men with essential hypertension over 1 year. Significant blood pressure reductions (p < 0.001) were achieved in both treatment groups: from 160/105 to 128/88 mmHg in group A (mean doses: hydrochlorothiazide 33 and sotalol 197 mg) and from 162/106 to 135/89 mmHg in group B (hydrochlorothiazide 33 and captopril 64 mg) after 12 months, respectively. No significant changes in body weight were observed in either treatment group. Triglycerides increased (p < 0.05) in both treatment groups (from 183 to 262 mg/dl in A, and from 160 to 196 mg/dl in B) and HDL cholesterol decreased (p < 0.001 and < 0.05) in both groups (from 45.1 to 35.7 mg/dl in A, and from 49.3 to 46.3 mg/dl in B), whereas LDL cholesterol increased significantly (p < 0.05) only in group A from 153 to 164 mg/dl. No significant changes were observed in total cholesterol nor in lipoprotein(a) concentrations in either treatment group. Fasting plasma glucose and hemoglobin A1 increased significantly (p < 0.05) only in group A after 1 year of treatment (from 91.6 to 98.0 mg/dl, and from 6.3 to 6.9%, respectively). Serum levels of creatinine and potassium decreased, and uric acid increased significantly under either combination. Our data show that the diuretic/beta-blocker combination has adverse effects on lipid and glucose metabolism after long-term therapy. The effects of the diuretic/ACE inhibitor combination on lipid metabolism are less pronounced and there are no adverse effects on glucose metabolism. However, the ACE inhibitor component could not completely counteract the metabolic effects of the diuretic. Both combinations have no effects on Lp(a). We conclude that the combination of hydrochlorothiazide with an ACE inhibitor has a better metabolic profile for the treatment of essential hypertension than the combination with a beta-blocker.     

Thermal Monitoring of Self-Checking Systems

With the increasing power density in integrated systems resulting from scaling down, the occurrence of field failures due to overheating has considerably increased. Faulty operation can be prevented by on-line temperature monitoring. This paper deals with questions of on-line temperature monitoring in safety-critical systems. First the possible temperature sensors are reviewed and basic principles of self-checking systems including such sensors are detailed, then a new temperature sensor cell with extremely good parameters designed especially for DfTT applications is presented. The basic questions of integrating thermal sensors into self-checking systems are also discussed.     

A stochastic nonlocal damage model

Deterministic nonlocal damage models permit avoiding spurious mesh sensitivity and predict structure size effect which is in accordance with experimental observations on notched specimens made of concrete. However, these deterministic models are unable to predict volume size effect exhibited by unnotched specimens in direct tension because the effect of heterogeneity has been introduced via a deterministic strain-softening behaviour.The main idea of our model is to consider two scales: the meso-scale (the representative volume) of size l ^r and the micro-scale, of size d (d l ^r). The plane is subdivided in square cells of size d. Each cell is supposed to be homogeneous and behaves in a purely brittle manner. The heterogeneity of the material properties are introduced by attributing to each cell a random threshold value picked according to a power law distribution function of parameter m. The breaking criterion is nonlocal.In finite element calculations, each cell is discretized in finite element meshes which have the same threshold value. Each finite element mesh behaves in a purely brittle manner and its breaking criterion is the ratio of the volume average of the elastic energy over a cube of size l ^r and the threshold value.Numerical simulations on notched and unnotched specimens will show that the proposed model yields mesh insensitive calculations and predicts both volume and structure size effects which are qualitatively in accordance with experimental observations.     

Curcumin antifungal and antioxidant activities are increased in the presence of ascorbic acid

The objective of this study was to evaluate the antifungal and antioxidant activities of curcumin, ascorbic acid and the mixture of these two compounds. For the antifungal assay, the minimum inhibitory concentrations (MIC) were determined using Candida strains (ATCC and clinical isolates). Curcumin alone inhibited growth of Candida albicans yeast cells, whereas ascorbic acid did not present effects. However, when the mixture of ascorbic acid and curcumin was assayed to determine the association of the two compounds, the curcumin MIC decreased 5- to 10-fold. In the antioxidant assays, the sum of the alone activities of curcumin and ascorbic acid were lower than the activity of the two-compound mixture. This study highlights the importance of the association between two common antioxidants in foods, to improve the antifungal and antioxidant activities of curcumin (in vitro), and can be applied to Candida spp. infection and diseases associated with oxidative stress.