3,752 research outputs found
Parallel matrix inversion techniques
In this paper, we present techniques for inverting sparse, symmetric and positive definite matrices on parallel and distributed computers. We propose two algorithms, one for SIMD implementation and the other for MIMD implementation. These algorithms are modified versions of Gaussian elimination and they take into account the sparseness of the matrix. Our algorithms perform better than the general parallel Gaussian elimination algorithm. In order to demonstrate the usefulness of our technique, we implemented the snake problem using our sparse matrix algorithm. Our studies reveal that the proposed sparse matrix inversion algorithm significantly reduces the time taken for obtaining the solution of the snake problem. In this paper, we present the results of our experimental work
Cobra: A Framework for Cost Based Rewriting of Database Applications
Database applications are typically written using a mixture of imperative
languages and declarative frameworks for data processing. Application logic
gets distributed across the declarative and imperative parts of a program.
Often, there is more than one way to implement the same program, whose
efficiency may depend on a number of parameters. In this paper, we propose a
framework that automatically generates all equivalent alternatives of a given
program using a given set of program transformations, and chooses the least
cost alternative. We use the concept of program regions as an algebraic
abstraction of a program and extend the Volcano/Cascades framework for
optimization of algebraic expressions, to optimize programs. We illustrate the
use of our framework for optimizing database applications. We show through
experimental results, that our framework has wide applicability in real world
applications and provides significant performance benefits
Timing feedback-inhibition of the male reproductive hormone axis
Hormonal methods of male contraception have addressed feedback-inhbition of the cascade of hormones that has evolved to regulate sperm production but high concentrations of testosterone (T) in the blood have not worked satisfactorily. We hypothesized that an episodic event, such as degranulation of gonadotropin-releasing hormone (GnRH) neurons in the hypothalamus, could be as well inhibited by episodic interference as by continuously-applied suppression. We used a computational model of hypothalamus-pituitary-gonad axis described by Veldhuis et al. to test the hypothesis that episodic administration of T would inhibit GnRH and/or luteinizing hormone (LH) secretion. A set of stochastic differential equations model feedback as well as feed-forward actions of GnRH, LH and T. The model predicted feedback-inhibition of GnRH pulses in a dose and frequency dependent manner when transdermal patches or injections delivering pulsatile T were applied. Since the published model did not address the effect of chronic GnRH deprivation on the viability of pituitary gonadotrophes, we introduced a function to address this issue. Incorporation of this function in the model allowed the prediction of a “holiday period” in the contraceptive regimen, during which exogenous T would not be needed to protect from conception. Pulsatile T delivered by real-life transdermal delivery system applied as per a parsimonious regimen reduced secretion of LH and T and fertility. The vitality function, proposed to account for survival and proliferation of pituitary gonadotrophes correlated with in vivo observations as extensive apoptosis in the anterior pituitary was observed after application of transdermal T
Insect inspired behaviours for the autonomous control of mobile robots
Animals navigate through various uncontrolled environments with seemingly little effort. Flying insects, especially, are quite adept at manoeuvring in complex, unpredictable and possibly hostile environments. Through both simulation and real-world experiments, we demonstrate the feasibility of equipping a mobile robot with the ability to navigate a corridor environment, in real time, using principles based on insect-based visual guidance. In particular we have used the bees’ navigational strategy of measuring object range in terms of image velocity. We have also shown the viability and usefulness of various other insect behaviours: (i) keeping walls equidistant, (ii) slowing down when approaching an object, (iii) regulating speed according to tunnel width, and (iv) using visual motion as a measure of distance travelled.<br /
Landmark based corridor discrimination
For a mobile robot to perform some sort of useful function it usually must have some sort of global understanding of its environment. This is usually expressed in the form of map. Through real-world experiments, using a mobile robot inspired by insect visual guidance, we present results showing the performance of a mobile robot in recognising a previously encountered corridor environment and discriminating between various corridors. This is achieved through the building and refinement of maps based on the observation of simple landmarks en route.<br /
A novel ingress node design for video streaming over optical burst switching networks
This paper introduces a novel ingress node design which takes advantage of video data partitioning in order to deliver enhanced video streaming quality when using H.264/AVC codec over optical burst switching networks. Ns2 simulations show that the proposed scheme delivers improved video traffic quality without affecting other traffic, such as best effort traffic. Although the extra network load is comparatively small, the average gain in video PSNR was 5 dB over existing burst cloning schemes, with a maximum end-to-end delay of 17 ms, and jitter of less than 0.35 ms
THE EFFECT OF SUN LIGHT EXPOSURE ON PREDIABETIC PATIENTS IN SOUTH INDIAN POPULATION
Objective: Type 2 diabetes evolves through a phase of normoglycemia and impaired glucose tolerance due to vitamin D deficiency. It was believed that sun light exposure is the natural way to improve the blood 25 (OH) D levels which delay or prevent disease progression. The study was to assess the effect of sunlight exposure in South Indian prediabetic population.
Methods: Data of the subjects were retrospectively collected in three continuous intervals. Total 160 subjects were identified as prediabetes based on inclusion and exclusion criteria. Age between 30 to 65 years subjects was randomly recruited for the study. Subjects were assigned into two groups based on sunlight exposure. All anthropometric and metabolic parameters were measured and interpreted.
Results: Between the group and within the group variation was assessed. In Comparative analysis sun light exposure group showed significant improvement in BMI (P=0.0309), glucose (P<0.0001), HbA1c (P<0.0001) and systolic BP (P=0.0042) were showed significant effect but not in diastolic BP (p>0.2893). In lipid profile, cholesterol (P=0.0002) and triglyceride (P=0.0019) showed significant improvement, but no significant effect was observed in HDL (P= 0.131), LDL (P=0.4735) level in sun light exposure group.
Conclusion: Daily exposure of sunlight can improve the disease condition. Along with sunlight exposure, intensive life style changes and appropriate vitamin D supplementation may need to prevent or delay the disease progression
Some aspects of Cold Deformation studies of Al-ZrB2 composites
In the present study Al-ZrB2 composite were made by powder metallurgy route adding different amounts of synthesized ZrB2 powder (2, 4, 6, 8, 10 wt. %). The ZrB2 powder was synthesized by using self-propagating high temperature synthesis (SHS). The samples of different aspect ratios (0.35, 0.5 and 0.65) were made and then sintered at 550oC under continuous argon gas atmosphere in a tubular furnace for 1 hour. The microstructure of the composites had shown that there is no chemical adhesion between Al matrix and ZrB2 reinforcement. Hardness of the composites increased with increase in the amount of ZrB2 reinforcement. The hardness of the composites increased with increase in amount of ZrB2 reinforcement. It was found that the formability stress index increased with the increase of preform fractional density and decreased with the aspect ratio. Relation between various stress ratios, axial strain and relative densities were analyzed. Statistical fitting methods are used on the curve drawn between the axial strain and the stress formability index. The compacts of lower aspect ratio and high initial preform density were found to have a very high fracture strain
Border Security using Raspberry Pi
Border Security is one of the major concerns for any country. Issues like political and economic instability in neighboring countries and border distribution demand a good border management and security system. The terrorist attacks that have been taking place over several years have increased the need of an improvised and high level security system. Hence, border infiltration monitoring and prevention is a system built to provide security at the borders. The device is based on the concepts of image capturing, cloud, and wireless data communication. Image processing concepts of noise removal, RGB to gray conversion, background subtraction and histogram of oriented gradients (HOG) are used to detect intrusion. Cloud is used to store the images of the intruder and retrieval at a farther place. Wireless data communication is used to send alert messages from the primary base station to the secondary base station. Further reactions are taken by handling manual robot for fire focusing to the enemy object by targeting and shooting and moving the robot towards enemy with robot detecting metals along its path for safety checking of any bomb present along its way
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