A quality based routing protocol for wireless mesh networks

Wireless mesh networks can provide low-cost solutions for extending the reach of wireless access points by using multi-hop routing over a set of stationary wireless routers. The routing protocol for these networks may need to address quality considerations to meet the requirements of the user. In this paper, we present a quality based routing protocol for wireless mesh networks that tries to maximize the probability of successful transmissions while minimizing the end-to-end delay. The proposed routing protocol uses reactive route discoveries to collect key parameters from candidate routes to estimate the probability of success and delay of data packets transmitted over them. To achieve accurate route quality assessments, a new route quality metric is proposed that uses performance models of data packet transmissions as opposed to estimating route quality from the transmission of control packets, which have different transmission characteristics. These models are developed after careful evaluations of multi-hop wireless transmissions and validated by computer simulations. Relevant parameters that can be used to assess the route quality metric using these models are explained. Extensive performance evaluations of the proposed quality based routing protocol are presented and its benefits in comparison to some other known routing protocols are discussed.     

Face recognition by generalized two-dimensional FLD method and multi-class support vector machines

This paper presents a novel scheme for feature extraction, namely, the generalized two-dimensional Fisher's linear discriminant (G-2DFLD) method and its use for face recognition using multi-class support vector machines as classifier. The G-2DFLD method is an extension of the 2DFLD method for feature extraction. Like 2DFLD method, G-2DFLD method is also based on the original 2D image matrix. However, unlike 2DFLD method, which maximizes class separability either from row or column direction, the G-2DFLD method maximizes class separability from both the row and column directions simultaneously. To realize this, two alternative Fisher's criteria have been defined corresponding to row and column-wise projection directions. Unlike 2DFLD method, the principal components extracted from an image matrix in G-2DFLD method are scalars; yielding much smaller image feature matrix. The proposed G-2DFLD method was evaluated on two popular face recognition databases, the AT&T (formerly ORL) and the UMIST face databases. The experimental results using different experimental strategies show that the new G-2DFLD scheme outperforms the PCA, 2DPCA, FLD and 2DFLD schemes, not only in terms of computation times, but also for the task of face recognition using multi-class support vector machines (SVM) as classifier. The proposed method also outperforms some of the neural networks and other SVM-based methods for face recognition reported in the literature.     

A micromachined impact microactuator driven by electrostatic force

This paper presents a novel micromachined actuator which is developed to produce precise and unlimited displacement. The actuator is driven by impact force between a silicon micro-mass and a stopper. The suspended silicon micro-mass is encapsulated between two glass plates and driven by electrostatic force. When the mass hits the stopper which is fixed on glass plates, impact force is generated to drive the whole actuator in a nano size step (/spl sim/10 nm). The overall dimension of the device is 3 mm /spl times/3 mm. The driving voltage is 100 V and average speed is 2.7 /spl mu/m/s. The total thickness is 600 /spl mu/m.     

Importance of conformation for the IgE reactivity of sarcoplasmic calcium-binding protein from the black tiger shrimp Penaeus monodon

Sarcoplasmic calcium-binding protein (SCP) is an EF-hand Ca²⁺-binding protein recently identified as a new crustacean allergen. Some EF-hand Ca²⁺-binding allergens, such as parvalbumin (fish allergen) and Bet v 4 (birch pollen allergen), have been shown to contain conformational-type IgE epitopes associated with the Ca²⁺-chelating. This study was performed to clarify the relationships between IgE reactivity and structure of the black tiger shrimp SCP. When analyzed by ELISA in the absence and presence of EGTA, the IgE reactivity of the black tiger shrimp SCP was found to be considerably reduced by Ca²⁺-depletion. Furthermore, circular dichroism spectral data showed a conformational difference between Ca²⁺-bound and Ca²⁺-depleted forms of the black tiger shrimp SCP. On the other hand, the synthetic 18 peptides spanning the entire amino acid sequence of the black tiger shrimp SCP were all assessed to have little IgE-binding ability by ELISA. Our results demonstrate that the IgE reactivity of the black tiger shrimp SCP is attributable mostly to conformational-type IgE epitopes, at least part of which is maintained by Ca²⁺-chelating.     

Supercritical Carbon Dioxide Extraction of Carotenoids from Pumpkin (Cucurbita spp.): A Review

Carotenoids are well known for their nutritional properties and health promoting effects representing attractive ingredients to develop innovative functional foods, nutraceutical and pharmaceutical preparations. Pumpkin (Cucurbita spp.) flesh has an intense yellow/orange color owing to the high level of carotenoids, mainly α-carotene, β-carotene, β-cryptoxanthin, lutein and zeaxanthin. There is considerable interest in extracting carotenoids and other bioactives from pumpkin flesh. Extraction procedures able to preserve nutritional and pharmacological properties of carotenoids are essential. Conventional extraction methods, such as organic solvent extraction (CSE), have been used to extract carotenoids from plant material for a long time. In recent years, supercritical carbon dioxide (SC-CO₂) extraction has received a great deal of attention because it is a green technology suitable for the extraction of lipophylic molecules and is able to give extracts of high quality and totally free from potentially toxic chemical solvents. Here, we review the results obtained so far on SC-CO₂ extraction efficiency and quali-quantitative composition of carotenoids from pumpkin flesh. In particular, we consider the effects of (1) dehydration pre-treatments; (2) extraction parameters (temperature and pressure); the use of water, ethanol and olive oil singularly or in combination as entrainers or pumpkin seeds as co-matrix.     

Involvement of sigma-receptors in the increase in contraction of mouse vas deferens induced by exogenous ATP

The mitochondrial FAD-dependent glycerol-3-phosphate dehydrogenase (mtGPD) plays an important role in the regulation of insulin secretion and has been postulated as a candidate responsible for the pathogenesis of non-insulin-dependent diabetes mellitus (NIDDM) in humans as well as in rodent models of NIDDM. Recent molecular genetic studies of the Goto-Kakizaki (GK) rat model of NIDDM have identified loci linked to NIDDM. To elucidate whether rat mtGPD might play a role in the pathogenesis of NIDDM, the rat mtGPD gene (Gpd2) was cloned, and a genetic marker for Gpd2 was developed. The gene mapped to the region of rat chromosome 3 that contains a region linked to NIDDM in the GK rat. Fluorescence in situ hybridization was also carried out to verify the map position.     

Pt-TiO2 thin films on glass substrates as efficient photocatalysts

Photocatalytic Pt-TiO₂ thin films of various thicknesses (ca. 20 to 100 nm) were prepared on Vycor glass substrates by spray-coating. The photocatalytic activity of the films was examined through the dehydrogenation of methanol in aqueous solution. The plot of the activity against the thickness of the film gave a sigmoidal curve. A drastic increase in activity was observed at about 50 nm thickness. From thin-film X-ray diffraction measurements of the films it was revealed that anatase was formed at a thickness of more than 50 nm, whereas amorphous TiO₂ was formed at thicknesses of less than 50 nm. The increase of activity was, therefore, attributed to the formation of anatase. Compared with powder catalysts, the thin films showed a remarkable improvement in specific photocatalytic activity due to the high dispersion of the catalyst.     

Gated-Clock Design of Linear-Feedback Shift Registers

In this paper, we will present a method to reduce the power consumption of the popular linear feedback shift register. The proposed scheme is based on the gated clock design approach and it can offer a significant power reduction, depending on technological characteristics of the employed gates. Moreover, the analytical condition that must be satisfied to achieve a power reduction of the gated-clock circuit has been found. Theoretical analysis was validated through many transistor-level SPECTRE simulations in CADENCE environment by using the 0.35- mum digital standard cells technology supplied by AMS. Simulation results have shown a power reduction of about 10% with a mean error of about 3% with respect to theoretical derivations.     

Effects of transforming growth factor beta on corneal epithelial and stromal cell function in a rat wound healing model after excimer laser keratectomy

BACKGROUND: Transforming growth factor beta (TGF-beta) regulates extracellular matrix deposition, cell proliferation, and migration, and is expressed in cornea. TGF-beta is thought to be involved in the corneal wound healing process. METHODS: The central corneal area (3 mm in diameter) of Lewis rats was ablated using PTK mode excimer laser and the wound healing process was observed at 12 and 24 h and 2, 5, 10, and 30 days after treatment. The expression of TGF-beta 1, -beta 2 and -beta 3, TGF-beta type I and type II receptors, alpha 3, alpha 5, beta 4 integrin subunits, laminin and fibronectin was studied immunohistochemically. Antibody neutralizing TGF-beta 1, -beta 2 and -beta 3 was administered intraperitoneally, 50 micrograms daily, for 5 days after the laser treatment to investigate the effects of TGF-beta function blockade. RESULTS: At the leading edge of the regenerating epithelium, no TGF-beta type I and type II receptors and beta 4 integrin subunits were expressed after 24 h. Regenerating epithelium covered the ablated area after 2 days. An abnormal fibrotic layer was formed in the subepithelial area. This layer contained round-shaped cells in the stroma in the early stage (2-5 days after laser ablation) and spindle-shaped fibroblast-like keratocytes after 10 days. Laminin and fibronectin expression increased in the fibrotic layer. The increased stromal cells expressed TGF-beta isoforms and TGF-beta receptors. Neutralizing TGF-beta inhibited the stromal cell increase in the laser ablated area after 5 days. CONCLUSION: TGF-beta may be involved in epithelial cell migration and stromal cell reaction during the corneal wound healing process after excimer laser ablation in rat models.