A Randomized Parallel Three-Dimensional Convex Hull Algorithm for Coarse-Grained Multicomputers

We present a randomized parallel algorithm for constructing the three-dimensional convex hull on a generic p-processor coarse-grained multicomputer with arbitrary interconnection network and n/p local memory per processor, where n/p ≥ p ^2+ε (for some arbitrarily small ε > 0). For any given set of n points in 3-space, the algorithm computes the three-dimensional convex hull, with high probability, in local computation time and O(1) communication phases with at most O(n/p) data sent/received by each processor. That is, with high probability, the algorithm computes the three-dimensional convex hull of an arbitrary point set in time , where Γ _n,p denotes the time complexity of one communication phase. The assumption n/p ≥ p ^2+ε implies a coarse-grained, limited parallelism, model which is applicable to most commercially available multiprocessors. In the terminology of the BSP model, our algorithm requires, with high probability, O(1) supersteps, synchronization period , computation cost , and communication cost O((n/p) g). Received October 30, 1995, and in revised form April 15, 1996, and in final form September 17, 1996.     

Effects of Processing on the Reduction of β-ODAP (β-N-Oxalyl-L-2,3-diaminopropionic acid) and Anti-Nutrients of Khesari Dhal,Lathyrus sativus

Effects of different processing techniques on the neurotoxin, β-ODAP (β- N -oxalyl-L-2,3-diaminopropionic acid), and the anti-nutritional compounds (phytate, polyphenols, trypsin and amylase inhibitors, and lectins) within four lines of Lathyrus sativus (high-, medium- and low-ODAP, and so-called ODAP-free) were investigated. Soaking of seeds in various media reduced the contents of these compounds to a varying and significant extent; losses were higher in freshly boiled water, alkaline and tamarind solutions than after soaking in drinking water. The highest losses in boiled water (65–70%) were observed for β-ODAP, followed by trypsin inhibitors (42–48%) and polyphenols (30–37%). Ordinary cooking and pressure cooking of pre-soaked seeds were found to be most effective in reducing the levels of all the natural toxicants examined, whilst fermentation and germination were more effective in destroying both of the enzyme inhibitors (amylase inhibitors by 69–71%; trypsin inhibitors by 65–66%) than either phytates or polyphenols. Lectins were not affected by most of these processes except by pressure cooking and fermentation. Dehusking of pre-soaked seeds significantly reduced β-ODAP levels, but this reduction was lower for the anti-nutrients. These findings and the high water solubility suggest that a simple and effective means of detoxifying Lathyrus by removing this neurotoxic amino acid may be practicable.     

Rev-erbα Knockout Reduces Ethanol Consumption and Preference in Male and Female Mice

Alcohol use is a contributor in the premature deaths of approximately 3 million people annually. Among the risk factors for alcohol misuse is circadian rhythm disruption; however, this connection remains poorly understood. Inhibition of the circadian nuclear receptor REV-ERBα is known to disrupt molecular feedback loops integral to daily oscillations, and impact diurnal fluctuations in the expression of proteins required for reward-related neurotransmission. However, the role of REV-ERBα in alcohol and substance use-related phenotypes is unknown. Herein, we used a Rev-erbα knockout mouse line and ethanol two-bottle choice preference testing to show that disruption of Rev-erbα reduces ethanol preference in male and female mice. Rev-erbα null mice showed the lowest ethanol preference in a two-bottle choice test across all genotypes, whereas there were no ethanol preference differences between heterozygotes and wildtypes. In a separate experiment, alcohol-consuming wildtype C57Bl/6N mice were administered the REV-ERBα/β inhibitor SR8278 (25 mg/kg or 50 mg/kg) for 7 days and alcohol preference was evaluated daily. No differences in alcohol preference were observed between the treatment and vehicle groups. Our data provides evidence that genetic variation in REV-ERBα may contribute to differences in alcohol drinking.     

View-invariant motion trajectory-based activity classification and recognition

Motion trajectories provide rich spatio-temporal information about an object's activity. The trajectory information can be obtained using a tracking algorithm on data streams available from a range of devices including motion sensors, video cameras, haptic devices, etc. Developing view-invariant activity recognition algorithms based on this high dimensional cue is an extremely challenging task. This paper presents efficient activity recognition algorithms using novel view-invariant representation of trajectories. Towards this end, we derive two Affine-invariant representations for motion trajectories based on curvature scale space (CSS) and centroid distance function (CDF). The properties of these schemes facilitate the design of efficient recognition algorithms based on hidden Markov models (HMMs). In the CSS-based representation, maxima of curvature zero crossings at increasing levels of smoothness are extracted to mark the location and extent of concavities in the curvature. The sequences of these CSS maxima are then modeled by continuous density (HMMs). For the case of CDF, we first segment the trajectory into subtrajectories using CDF-based representation. These subtrajectories are then represented by their Principal Component Analysis (PCA) coefficients. The sequences of these PCA coefficients from subtrajectories are then modeled by continuous density hidden Markov models (HMMs). Different classes of object motions are modeled by one Continuous HMM per class where state PDFs are represented by GMMs. Experiments using a database of around 1750 complex trajectories (obtained from UCI-KDD data archives) subdivided into five different classes are reported.     

Scalable parallel implementations of list ranking on fine-grainedmachines

We present analytical and experimental results for fine-grained list ranking algorithms. We compare the scalability of two representative algorithms on random lists, then address the question of how the locality properties of image edge lists can be used to improve the performance of this highly data-dependent operation. Starting with Wyllie's algorithm and Anderson and Miller's randomized algorithm as bases, we use the spatial locality of edge links to derive scalable algorithms designed to exploit the characteristics of image edges. Tested on actual and synthetic edge data, this approach achieves significant speedup on the MasPar MP-1 and MP-2, compared to the standard list ranking algorithms. The modified algorithms exhibit good scalability and are robust across a wide variety of image types. We also show that load balancing on fine grained machines performs well only for large problem to machine size ratios     

Issues in storage and retrieval of multimedia data

As the proliferation of multimedia systems continues in diverse application areas, it is becoming increasingly apparent that the performance of the I/O subsystem is a critical limiting factor in the usefulness of such systems. This has spurred extensive research to discover and design efficient and robust I/O systems for the storage and retrieval of multimedia data. To mitigate the effects of the I/O bottleneck in multimedia application environments, we must employ novel technologies and efficient algorithms, and we must use available resources carefully. This paper identifies some significant issues involved and presents a survey of the techniques developed or proposed during recent years to make multimedia I/O more efficient. e-mail: ashfaq@eecis.udel.edu     

Virtual private networks: an overview with performance evaluation

Virtual private networks have gained immense popularity among commercial and defense organizations because of their capability to provide secure connectivity at lower costs. Several commercial and open source VPN products are now available that can be configured to provide VPN services with varying characteristics. This article studies some of the most popular open-source Linux-based VPN solutions (OSLVs) and compares them with respect to network performance (measured in terms of overhead, bandwidth utilization, and latency/jitter), features and functionalities (e.g., algorithm plugins and routing), and operational concerns (defined by security and scalability). Our experiments suggest that there is no single OSLV solution that excels in all considered aspects, and a combination of different VPN products and/or trade-off among desired characteristics may be required to deliver optimal performance. Our experiments also suggest that on an average, OSLVs using UDP-based tunnels have 50 percent lower overhead, 80 percent higher bandwidth utilization, and 40-60 percent lower latency/jitter than those using TCP.     

A Simplified Model Predictive Control of Four-Leg Two-Level Inverter

Abstract

This article proposes current control strategy for four-leg two-level voltage source inverters (VSI). This strategy is based on model predictive control (MPC) approach and presents its comparison with finite control set (FCS) model technique. Besides providing a fast dynamic response, proposed technique replaces complex modulation stage and PI controller being used in earlier classical control techniques. Moreover, the proposed methodology selects the switching sequence which reduces tracking error between output and applied reference currents using cost function optimization. This shows the improvement of system response like FCS model technique. However, FCS model technique results in calculation stress and computation burden; resulting computational delay and extra power consumption by the processor. This problem is solved with the help of proposed single predictive technique which makes the inverter more suitable for large time horizon operations and small sampling time instants. The computational delay is reduced up to 6% compared to the case of FCS-MPC controlled inverter. Performance of proposed simplified technique is analyzed and compared with FCS-MPC controlled system with the help of different types of reference signals. This work will boost the industrial application of four-leg two-level VSI by increasing dynamic response and removing complex modulation stage.     

Factors affecting the levels of catechins and caffeine in tea beverage: estimated daily intakes and antioxidant activity

Increased public awareness of health benefits of green tea is generally based on the high polyphenol content of tea leaves and the resulting beverage. A number of factors, such as species, season, agronomic condition and age of the leaves, are known to affect the composition of commercial teas. In the present study the effects of factors associated with domestic preparation and analytical methods, such as brewing time, concentration, solvent and type of tea product, on levels of catechins and caffeine, antioxidant activity and estimated daily intakes were investigated. There were large variations in the levels of total catechins: 43 and 117 mg g^?1 dry matter (DM) (brewed for 30 s and 5 min respectively); 72 and 161 mg g^?1 DM (extracted in boiling water and 50% acetonitrile respectively); 72 and 117 mg g^?1 DM (a tea bag and tea leaves respectively). The effects on caffeine content were comparatively smaller. These variations consequently led to considerable variations in estimated daily intakes based on three cups (600 ml), ranging between 538 and 2014 mg g^?1 DM of total catechins and between 103 and 466 mg g^?1 DM of caffeine. The antioxidant activity was highest (26 680 µmol g^?1 DM) for tea leaves brewed for 5 min and lowest (10 110 µmol g^?1 DM) for a tea bag product brewed for 1 min. Copyright © 2005 Society of Chemical Industry     

Efficient transmission of MPEG‐2 video bit streams over HIPERLAN/2

This paper studies the transmission of MPEG‐2 video bit streams over HIPERLAN/2 based wireless local area networks (WLANs). HIPERLAN/2, a WLAN standard introduced by ETSI (the European Telecommunications Standards Institute), is well known for its ability to operate under different physical (PHY) modes (modulation schemes) and adaptively switch its modes within a single transmission session. Each physical mode has certain throughput and error resilience associated with it. The presence of multiple physical modes can be exploited to achieve Quality of Service (QoS) guarantees for application parameters such as throughput, bit error rate (BER), jitter etc. In this paper, we first study the relationship of different PHY modes with BER and throughput. Based on this study, different content based marking algorithms are presented and analyzed that partitions the input video bitstream into multiple segments, where each segment is deemed suitable for transmission over HIPERLAN/2 operating under a specific PHY mode. We show that for a given video bit stream, the use of multiple PHY modes chosen based on the characteristics of underlying video data yields superior throughput and better picture quality in terms of pixel signal to noise ratio (PSNR). From the power consumption point of view, the marking algorithms can achieve desired throughput or PSNR with lower signal to interference ratio (SIR) levels thus saving battery power and extending the overall battery life. Copyright © 2004 John Wiley & Sons, Ltd.