Distributed MST for constant diameter graphs

This paper considers the problem of distributively constructing a minimum-weight spanning tree (MST) for graphs of constant diameter in the bounded-messages model, where each message can contain at most B bits for some parameter B. It is shown that the number of communication rounds necessary to compute an MST for graphs of diameter 4 or 3 can be as high as and , respectively. The asymptotic lower bounds hold for randomized algorithms as well. On the other hand, we observe that O(log n) communication rounds always suffice to compute an MST deterministically for graphs with diameter 2, when B = O(log n). These results complement a previously known lower bound of for graphs of diameter Ω(log n). An extended abstract of this work appears in Proceedings of 20th ACM Symposium on Principles of Distributed Computing, August 2001.     

Arrest trajectories of adult offenders with a serious mental illness.

We examined patterns and correlates of arrest/re-arrests among offenders with a serious mental illness over a 4-year period. County criminal justice records and health and social service datasets were used to identify and describe inmates jailed in Pinellas County, Florida, between 7/03 and 6/04. A total of 3,769 participants (10.1% of arrestees) had a serious mental illness. Participants averaged 4.6 arrests (SD = 3.9, median = 4) and 150.6 days in jail (SD = 175.0, median = 90).Working from the trajectories of offending theory and literature we used latent class growth analysis to identify three classes of offenders with consistent numbers of arrests over a 4-year period and nearly parallel arrest trajectories; a sporadic arrest class (n = 469) with minimal arrests, a low arrest chronic class (n = 3,090, about one arrest/year); and a high arrest chronic class (n = 210, about four arrests/year). Analysis of arrests by age group within each of the classes suggested that for the low and high arrest chronic classes arrest rates persist throughout adult life. In multinomial logistic regression, homelessness, a co-occurring substance abuse diagnosis, fewer mental health outpatient service contacts and more mental health emergency room/inpatient contacts were associated with being in a class with more arrests. Arrests among offenders with a serious mental illness appear to be unusually high, to be firmly established in late adolescence and to persist over time. Successful strategies to reduce the arrest rates of this population must address the needs of these offenders early in their criminal careers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

New maximum likelihood motion estimation schemes for noisy ultrasound images

When performing block-matching based motion estimation with the ML estimator, one would try to match blocks from the two images, within a predefined search area. The estimated motion vector is that which maximizes a likelihood function, formulated according to the image formation model. Two new maximum likelihood motion estimation schemes for ultrasound images are presented. The new likelihood functions are based on the assumption that both images are contaminated by a Rayleigh distributed multiplicative noise. The new approach enables motion estimation in cases where a noiseless reference image is not available. Experimental results show a motion estimation improvement with regards to other known ML estimation methods.     

Approximating the Visible Region of a Point on a Terrain

Given a terrain and a point p on or above it, we wish to compute the region R _p that is visible from p. We present a generic radar-like algorithm for computing an approximation of R _p . The algorithm interpolates the visible region between two consecutive rays (emanating from p) whenever the rays are close enough; that is, whenever the difference between the sets of visible segments along the cross sections in the directions specified by the rays is below some threshold. Thus the density of the sampling by rays is sensitive to the shape of the visible region. We suggest a specific way to measure the resemblance (difference) and to interpolate the visible region between two consecutive rays. We also present an alternative algorithm, which uses circles of increasing radii centered at p instead of rays emanating from p. Both algorithms compute a representation of the (approximated) visible region that is especially suitable for is-visible-from-p queries, i.e., given a query point q on the terrain determine whether q is visible from p. Finally, we report on the experiments that we performed with these algorithms and with their corresponding fixed versions, using a natural error measure. Our main conclusion is that the radar-like algorithm is significantly better than the others.     

A quantitative foundation for defining and manipulating deals to facilitate automated e-commerce

We propose a goal programming framework that aims at automating e-commerce transactions. This framework consists of three basic layers: deal definition—defining the deal’s parameters and associated constraints (e.g., item, price, delivery dates); deal manipulation—a collection of procedures for shaping deals to attain desired goals (e.g., earliest delivery and minimum price) and an applications layer that employs these procedures within some negotiations settings (e.g., an auction-related application presents a “better offer” while bidding on a contract). Our proposed foundation is rich enough to support a wide array of applications ranging from 1-1 and 1-n negotiations (auctions) to deal valuation and deal splitting. Whereas the techniques are appropriate to a multitude of settings, we shall mainly present them in the context of business-to-business (B2B) commerce where we see the greatest short term benefits. O. Shmueli’s work is partially supported by the Fund for the Promotion of Research at the Technion.     

"Speed of scanning in primary memory in persons with dementia of the Alzheimer type": Correction.

Reports editorial errors in the original article by T. L. Boaz and D. R. Denney (Psychology and Aging, 1993[Jun], Vol 8[2], 294–300). A short segment of text was misplaced in the Results section; the corrected text is included. (The following abstract of this article originally appeared in record 1993-42036-001.) The nature of the search of primary memory by persons with a presumptive diagnosis of mild Alzheimer's disease (dementia of the Alzheimer type [DAT]) was compared with that of normal elderly and young persons using the S. Sternberg (1966) paradigm. DAT Ss evidenced a substantial deficit in the speed of scanning in primary memory and a deficit in at least one other stage of processing. These findings are consistent with the hypothesis that the decline in memory performance evidenced by persons with DAT may be attributable to an increase in the time requirements of mnemonic processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Resource allocation in stochastic,finite-capacity,multi-project systems through the cross entropy methodology

This paper addresses the problem of resource allocation in a finite-capacity, stochastic (random) and dynamic multi-project system. The system is modeled as a queuing network that is controlled by limiting the number of concurrent projects. We propose a Cross Entropy (CE) based approach to determine near-optimal resource allocations to the entities that execute the projects. The performance of the suggested approach is demonstrated through numerical experiments and compared to that of a heuristic, rough-cut based method.     

Hydrocephalus in children: neurosurgical and neuroimaging concerns

The neuroimaging of hydrocephalus from the perspective of the pediatric neurosurgeon is discussed. Processes with new developments in therapy and imaging are described, including congenital causes of hydrocephalus, unilateral hydrocephalus, trapped fourth ventricle, and benign external hydrocephalus.     

Real-time disruption management in a two-stage production and inventory system

This paper presents a general disruption management approach for a two-stage production and inventory control system. A penalty cost for deviations of the new plan from the original plan is incorporated and the concept of a disruption recovery time window is introduced. We define two classes of problems: one with fixed setup epochs and another with flexible setup epochs. With linear or quadratic penalty functions for production/ordering quantity change and fixed setup epochs, the best recovery plan is obtained by solving a quadratic mathematical programming problem. With convex penalty functions for quantity changes and flexible setup epochs, it is shown that the second stage orders have identical order quantities within each production cycle. Therefore, in a lot-for-lot system, the ordering and production quantities for both stages are the same. As a special case, we consider disruption recovery problems with short time windows spanning one or two production cycles. We also discuss solution procedures for both major and minor disruption problems and give an extension for the case of multiple retailers. Throughout the paper managerial insights are presented that indicate how a company should respond to various types of disruptions during its operations.