Dynamic Voltage Scaling Techniques for Energy Efficient Synchronized Sensor Network Design

Building energy-efficient systems is one of the principal challenges in wireless sensor networks. Dynamic voltage scaling (DVS), a technique to reduce energy consumption by varying the CPU frequency on the fly, has been widely used in other settings to accomplish this goal. In this paper, we show that changing the CPU frequency can affect timekeeping functionality of some sensor platforms. This phenomenon can cause an unacceptable loss of time synchronization in networks that require tight synchrony over extended periods, thus preventing all existing DVS techniques from being applied. We present a method for reducing energy consumption in sensor networks via DVS, while minimizing the impact of CPU frequency switching on time synchronization. The system is implemented and evaluated on a network of 11 Imote2 sensors mounted on a truss bridge and running a high-fidelity continuous structural health monitoring application. Experimental measurements confirm that the algorithm significantly reduces network energy consumption over the same network that does not use DVS, while requiring significantly fewer re-synchronization actions than a classic DVS algorithm.unpublishedis peer reviewe

Nutritional properties of indigenous fermented condiment (ogiri) produced from partial substitution of castor oil bean (Ricinus communis) with soybean (Glycine max) seeds

Recently, in Nigeria, there has been a series of controversial publications and debates over the use of seasoning cubes and monosodium glutamate as cancer inducing agents. With this, the use of local condiments like Ogiri has become an option. Ogiri is traditionally produced from castor oil beans which is scarce in some communities. This study therefore explored the possibility of substituting castor oil bean with soybean to obtain an acceptable Ogiri. Proximate, mineral and vitamin composition and sensory characteristics of the substituted Ogiri samples produced were evaluated using standard methods. With increase in soybean substitution levels, proximate analysis showed an increase in crude protein (17.33%-31.68%), crude fibre (0.47-1.71%) and fat (13.76-20.23%) contents while ash (3.63-3.21%) and carbohydrate (48.13%-23.55%) contents decreased. Mineral contents increased from 46.11 - 80.21, 60.25 - 73.83, 80.33 - 99.42, 118.10 - 794.38, 1.63 - 6.32 and 0.49 - 1.48 mg/100g for calcium, magnesium, phosphorous, potassium, iron and zinc, respectively. Potassium was the most abundant mineral in the samples. Also, retinol (11.63-16.26 mg/100g), vitamin B1 (0.10-0.21 mg/100g), vitamin B2 (10.37-14.79 mg/100g), vitamin B3 (9.21-9.91 mg/100g), vitamin C (2.43-5.85 mg/100g) and vitamin E (6.43-11.25 mg/100g) increased significantly. Sensory analysis revealed that the Ogiri sample with 50% soybean inclusion and the control had the best organoleptic properties. Therefore, soybean substitution of up to 50% gave a better acceptable Ogiri with improved nutrient contents. Keywords: “ogiri”, castor oil bean, soybea

Equality of averaged and quenched large deviations for random walks in random environments in dimensions four and higher

We consider large deviations for nearest-neighbor random walk in a uniformly elliptic i.i.d. environment. It is easy to see that the quenched and the averaged rate functions are not identically equal. When the dimension is at least four and Sznitman's transience condition (T) is satisfied, we prove that these rate functions are finite and equal on a closed set whose interior contains every nonzero velocity at which the rate functions vanish.Comment: 17 pages. Minor revision. In particular, note the change in the title of the paper. To appear in Probability Theory and Related Fields

Heavy Metals Distribution and Pollution in the Sediments of the Wadi Gaza Mouth, Eastern Mediterranean Coast, Palestine

Wadi Gaza is the most important wetland in Gaza Strip. Due to the difficult economic conditions, the Israeli occupation and lack of the resources, Wadi Gaza became a place for solid and liquid waste disposal from surrounding provinces. The aim of this study is to assess the heavy metals in the sediments of the Wadi Gaza, North, and South of downstream along the beach of Gaza Strip. This was achieved through sediment sampling along the course of the Wadi downstream; north and south of the beach sands, and the geochemical analysis was done in the Ministry of Health Laboratories. The concentrations of Mn, Zn, Ni, Cd, Cu, and Pb were determined in the sediments, using atomic absorption spectrophotometer

The importance of socio-economic context for social marketing models for improving reproductive health: Evidence from 555 years of program experience

BACKGROUND: Over the past two decades, social marketing programs have become an important element of the national family planning and HIV prevention strategy in several developing countries. As yet, there has not been any comprehensive empirical assessment to determine which of several social marketing models is most effective for a given socio-economic context. Such an assessment is urgently needed to inform the design of future social marketing programs, and to avoid that programs are designed using an ineffective model. METHODS: This study addresses this issue using a database of annual statistics about reproductive health oriented social marketing programs in over 70 countries. In total, the database covers 555 years of program experience with social marketing programs that distribute and promote the use of oral contraceptives and condoms. Specifically, our analysis assesses to what extent the model used by different reproductive health social marketing programs has varied across different socio-economic contexts. We then use random effects regression to test in which socio-economic context each of the models is most successful at increasing use of socially marketed oral contraceptives and condoms. RESULTS: The results show that there has been a tendency to design reproductive health social marketing program with a management structure that matches the local context. However, the evidence also shows that this has not always been the case. While socio-economic context clearly influences the effectiveness of some of the social marketing models, program maturity and the size of the target population appear equally important. CONCLUSIONS: To maximize the effectiveness of future social marketing programs, it is essential that more effort is devoted to ensuring that such programs are designed using the model or approach that is most suitable for the local context

Selected recollections of my relationship with Leo Breiman

During the period 1962--1964, I had a tenure track Assistant Professorship in Mathematics at Cornell University in Ithaca, New York, where I did research in probability theory, especially on linear diffusion processes. Being somewhat lonely there and not liking the cold winter weather, I decided around the beginning of 1964 to try to get a job in the Mathematics Department at UCLA, in the city in which I was born and raised. At that time, Leo Breiman was an Associate Professor in that department. Presumably, he liked my research on linear diffusion processes and other research as well, since the department offered me a tenure track Assistant Professorship, which I happily accepted. During the Summer of 1965, I worked on various projects with Sidney Port, then at RAND Corporation, especially on random walks and related material. I was promoted to Associate Professor, effective in Fall, 1966, presumably thanks in part to Leo. Early in 1966, I~was surprised to be asked by Leo to participate in a department meeting called to discuss the possible hiring of Sidney. The conclusion was that Sidney was hired as Associate Professor in the department, as of Fall, 1966. Leo communicated to me his view that he thought that Sidney and I worked well together, which is why he had urged the department to hire Sidney. Anyhow, Sidney and I had a very fruitful and enjoyable collaboration in probability and, to a much lesser extent, in theoretical statistics, for a number of years thereafter.Comment: Published in at http://dx.doi.org/10.1214/10-AOAS431 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Quenched large deviations for multidimensional random walk in random environment with holding times

We consider a random walk in random environment with random holding times, that is, the random walk jumping to one of its nearest neighbors with some transition probability after a random holding time. Both the transition probabilities and the laws of the holding times are randomly distributed over the integer lattice. Our main result is a quenched large deviation principle for the position of the random walk. The rate function is given by the Legendre transform of the so-called Lyapunov exponents for the Laplace transform of the first passage time. By using this representation, we derive some asymptotics of the rate function in some special cases.Comment: This is the corrected version of the paper. 24 page