Efficient emulation of single-hop radio network with collision detection on multi-hop radio network with no collision detection

Summary This paper presents an efficient randomized emulation ofsingle-hop radio networkwith collision detection onmulti-hop radio networkwithout collision detection. Each step of the single-hop network is emulated by rounds of the multi-hop network and succeeds with probability 1–. (n is the number of processors,D the diameter and the maximum degree). It is shown how to emulate any polynomial algorithm such that the probability of failure remains . A consequence of the emulation is an efficient randomized algorithm for choosing a leader in a multi-hop network. Reuven Bar-Yehuda was born in Iran, on July 17th 1951. Received B.A., M.Sc., and D.Sc. in Computer Science from the Technion — Israel Institute of Technology, Haifa, Israel, in 1978, 1980, and 1983, respectively. He is currently a Senior Lecturer of Computer Science at the Technion. From 1984 to 1986, he was a visiting assistant professor in the Computer Science Dept. at the Duke Univesity His research interests include computational geometry, VLSI, graph algorithms and distributed algorithms. Oded Goldreich was born in Tel-Aviv, Israel, on February 4th 1957. Received B.A., M.Sc., and D.Sc. in Computer Science from the Technion — Israel Institute of Technology, Haifa, Israel, in 1980, 1982, and 1983, respectively. He is currently an Associate Professor of Computer Science at the Technion. From 1983 to 1986, he was a postdoctoral fellow at MIT's Laboratory for Computer Science. His research interests include cryptography and related areas, relation between randomness and algorithms, and distributed computation. Alon Itai was born in Scotland, on December 12th 1946. Received B.Sc. in Mathematics from the Hebrew University in Jerusalem in 1969. M.Sc., and Ph.D. in Computer Science from the Weizmann Institute of Science, Rehovot, Israel in 1971 and 1976. He is currently an Associate Professor of Computer Science at the Technion. His research interests include randomized and distributed algorithms, computational learning theory and performance evaluation.The second author was partially supported by grant No. 86-00301 from the United States—Israel Bi-national Science Foundation BSF), Jerusalem, Israel.     

Dynamic stills and clip trailers

We propose a method for generating visual summaries of video. It reduces browsing time, minimizes screen-space utilization, while preserving the crux of the video content and the sensation of motion. The outputs are images or short clips, denoted as dynamic stills or clip trailers, respectively. The method selects informative poses out of extracted video objects. Optimal rotations and transparency supports visualization of an increased number of poses, leading to concise activity visualization. Our method addresses previously avoided scenarios, e.g., activities occurring in one place, or scenes with non-static background. We demonstrate and evaluate the method for various types of videos.     

Design and Construction of High Multitier Shoring Towers: Case Study

Shoring towers are the common formwork solution for high-clearance construction, but there are not many documented cases of extremely high towers. This paper reports on a project in which 60-m-(200-ft-) high shoring towers were used for slab formwork. The paper describes the design and construction of the formwork, with a focus on aspects unique to high multitier towers. The various considerations made are presented, and data and information are provided that may assist practitioners facing similar engineering undertakings. Special attention is given to the organization of the work, in light of the scarcity of data pertaining to shoring towers of such heights. Measured assembly and disassembly work inputs are presented and analyzed, and the validity of a model to predict work inputs in multitier tower erection is examined.     

Perception of musical consonance and dissonance: an outcome of neural synchronization

While a number of theories have been advanced to account for why musical consonance is related to simple frequency ratios, as yet there is no completely satisfying explanation. Here, we explore the theory of synchronization properties of ensembles of coupled neural oscillators to demonstrate why simple frequency ratios may have achieved a special status and why they are important for auditory perception. The analysis shows that the mode-locked states ordering give precisely the standard ordering of consonance as often listed in Western music theory. Our results thus indicate the importance of neural synchrony in musical perception.     

Study of core-shell platinum-based catalyst for methanol and ethylene glycol oxidation

A Ru_core-Pt_shell, XC72-supported catalyst was synthesized in a two-step process: first, by deposition of Ru on XC72 by the polyol process and then by deposition of Pt on the XC72-supported Ru, with NaBH₄ as reducing agent. The structure and composition of this core-shell catalyst were determined by EDS, XPS, TEM and XRD. Electrochemical characterization was determined with the use of cyclic voltammetry and chronoamperometry. The methanol and ethylene glycol oxidation activities of the core-shell catalyst were studied at 80 °C and compared to those of a commercial catalyst. It was found to be significantly better (in terms of A g⁻¹ of Pt) in the case of methanol oxidation and worse in the case of ethylene glycol oxidation. Possible reasons for the lower ethylene glycol oxidation activity of the core-shell catalyst are discussed.     

The effect of irrigation level and harvest mechanization on virgin olive oil quality in a traditional rain‐fed ‘Souri’ olive orchard converted to irrigation

BACKGROUND: Olive trees are generally grown under rain‐fed conditions. Since yield response to application of water in the growing season may be considerable, irrigation is increasingly introduced to existing, mature orchards. An additional feature of modernization of olive cultivation is mechanical harvesting. To investigate the effect of irrigation level on the quality of virgin olive oil (VOO) produced from cv. Souri, six regimes, ranging from deficit to excess, were applied to trees in a mature, traditional orchard as it was converted to irrigation. Furthermore, in order to investigate the effect of damage incurred during harvest, oil quality of hand‐picked fruit was compared to that of mechanically harvested olives. RESULTS: Data were collected from two consecutive growing seasons. Increased irrigation quantity increased the free acidity level of the oil and decreased the total phenol content of VOO, while the peroxide level of the oil was not affected. Oil of hand‐picked fruits had lower free acidity, higher polyphenol content and slightly lower peroxide level compared to the oil of mechanically harvested olives. CONCLUSION: Fruits from irrigated trees demonstrated an apparent sensitivity to mechanical wounding that subsequently led to increased free acidity, increased peroxide level and decreased total phenol content in oil. Management of irrigated orchards including method and timing of harvest and oil extraction techniques should consider these results in order to optimize production of high‐quality oil. Copyright © 2008 Society of Chemical Industry     

Crosswind sensing from optical-turbulence-induced fluctuations measured by a video camera

We present a novel method for remote sensing of crosswind using a passive imaging device, such as a video recorder. The method is based on spatial and temporal correlations of the intensity fluctuations of a naturally illuminated scene induced by atmospheric turbulence. Adaptable spatial filtering, taking into account variations of the dominant spatial scales of the turbulence (due to changes in meteorological conditions, such as turbulence strength, or imaging device performance, such as frame rate or spatial resolution), is incorporated into this method. Experimental comparison with independent wind measurement using anemometers shows good agreement.     

Response regulator output in bacterial chemotaxis

Chemotaxis responses in Escherichia coli are mediated by the phosphorylated response-regulator protein P-CheY. Biochemical and genetic studies have established the mechanisms by which the various components of the chemotaxis system, the membrane receptors and Che proteins function to modulate levels of CheY phosphorylation. Detailed models have been formulated to explain chemotaxis sensing in quantitative terms; however, the models cannot be adequately tested without knowledge of the quantitative relationship between P-CheY and bacterial swimming behavior. A computerized image analysis system was developed to collect extensive statistics on freeswimming and individual tethered cells. P-CheY levels were systematically varied by controlled expression of CheY in an E.coli strain lacking the CheY phosphatase, CheZ, and the receptor demethylating enzyme CheB. Tumbling frequency was found to vary with P-CheY concentration in a weakly sigmoidal fashion (apparent Hill coefficient approximately 2.5). This indicates that the high sensitivity of the chemotaxis system is not derived from highly cooperative interactions between P-CheY and the flagellar motor, but rather depends on nonlinear effects within the chemotaxis signal transduction network. The complex relationship between single flagella rotation and free-swimming behavior was examined; our results indicate that there is an additional level of information processing associated with interactions between the individual flagella. An allosteric model of the motor switching process is proposed which gives a good fit to the observed switching induced by P-CheY. Thus the level of intracellular P-CheY can be estimated from behavior determinations: approximately 30% of the intracellular pool of CheY appears to be phosphorylated in fully adapted wild-type cells.     

Correlation Between the Total Morphology of an Epoxy System and Some of its Properties

Due to the ever growing use of epoxy resins for structural applications, more information is required about their structure-properties relationship. Much work was done on this subject by us and by others, but many questions still remain unanswered. Some problems which require more detailed studies are the influence of factors like compositional changes in the resin (ratio of prepolymer-curing agent), postcuring and cooling of the polymerized resin from temperatures above T_g to room temperature, on physical properties of the product.