Sensitivity of Optimum Workforce Size to Employee Absenteeism in Stochastic Workload Situations

This paper presents the results of a simulation model developed to explore the relationship between unit cost and a number of primary production variables for a large warehouse operation of a major national retailer. The output of the simulation model includes a plot of total cost per completed unit for each combination of workforce size. Results indicate that under the conditions studied the total cost per completed unit is not particularly sensitive to workforce size and absenteeism patterns, and therefore insensitive to traditional managerial measures (such as over-staffing) to reduce these unit costs. This result is counter-intuitive and leads to the conclusion that the “fine turning” of staff levels as currently being attempted is perhaps not necessary.     

Peer nomiations as a predictor of multistage promotions in a ramified organization.

Studied the validity of peer nominations (PNs) as a predictor of advancement in rank in the Israel Defense Forces on a population of 125 platoons encompassing 3897 soldiers. Results indicate that PNs obtained at early stages of training predicted promotion at several successive stages in the soldier's military career with a high degree of validity and correlations generally around .6 and .7. Predictions were valid for success within groups of different personnel, and with different purposes, and criteria for achievement. PNs were also found to contribute markedly to the predictive validity of conventional psychological screening measures, suggesting the value of combining psychometric and sociometric procedures for personnel selection. (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fast method for physical optics propagation of high-numerical-aperture beams

A method is presented that expands the scheme of physical optics propagation beyond the Fresnel approximation to include beams that are nonparaxial. The formalism retains most of the calculation advantages of the Fresnel approach; i.e., it is based on a single Fourier transform step. The kernel of the new transformation is no longer separable in Cartesian coordinates; thus the formalism can account for astigmatic coupling effects originating purely from diffraction. The validity limits of the proposed algorithm are explored. Analytical expressions, numerical simulation results, and experimental data are compared.     

Control of magnetophoretic mobility by susceptibility-modified solutions as evaluated by cell tracking velocimetry and continuous magnetic sorting

With the analytical expression for the magnetophoretic mobility of an ideal, linearly polarizable sphere undergoing creeping motion in viscous medium, we have shown that both attractive and repulsive motions are possible in the magnetic field. We have validated theoretical predictions using magnetic monodisperse microspheres of 5.2-microm diameter and nonmagnetic polystyrene microspheres of 6.99-microm diameter suspended in solutions of paramagnetic ions. The microsphere magnetophoretic mobility was measured using a modified particle tracking velocimetry system, developed in-house and called a cell tracking velocimeter. The product of measured mobility and viscosity agrees well with the theoretical prediction, differing only by approximately 11%. Further, a 26% increase in resolution between magnetic and nonmagnetic particle distributions was evaluated when paramagnetic ion carrier was used instead of water. Continuous particle sorting based on differences in magnetophoretic mobility was performed with another device developed by us, the quadrupole magnetic flow sorter (QMS). In the QMS, the introduction of paramagnetic ions into the carrier was effective in suppressing nonspecific crossover (i.e., the transport of low-mobility particles into the magnetic particle fraction) in particles and in biologically relevant red blood cells and thus showed promise as a means of increasing the purity of the magnetic separation.     

A Dynamic Tree Algorithm for Peer-to-Peer Ridesharing Matching

Networks and Spatial Economics - On-demand peer-to-peer ridesharing services provide flexible mobility options and are expected to alleviate congestion by sharing empty car seats. An efficient...     

Enhancement of luminescence of Rhodamine B by gold nanoparticles in thin films on glass for active optical materials applications

Fluorescent dyes in solid matrices have many potential applications provided that their high optical efficiencies are achieved. We present here gold nanoparticles formed and incorporated together with fluorescent dye Rhodamine B into a film of polyvinyl alcohol (PVA). The increase of fluorescence of the dye results from its interaction with surface plasmons. The electric charge on the gold nanoparticles and the distance between them and the dye molecules has a significant effect on the fluorescence intensity. Fluorescence enhancement of 74% was achieved for the negatively charged particles. Dynamic measurements reveal decrease of fluorescent lifetimes of the dye in presence of gold nanoparticles. Our findings enable utilization of films with enhanced fluorescence in optical materials such as luminescence solar concentrators, solid state tunable laser and active waveguides.     

Maturing,Technology-Based,Born-Global Companies: Surviving Through Mergers and Acquisitions

To date, there has been little research about the corporate growth of born-global companies and relatively little data exist about their maturation, survival as independent companies (or failure to do so) and their international strategies. The present paper is based on an empirical study of Israeli technology-based companies that were identified in the late 1990s as born global. We collected data about the continuing development of these firms for the decade spanning 2000–2009. Our findings show that maturing technology-based, born-global companies can increase their chances of survival by acquiring other firms. Although such acquisitions do not increase profits, they allow born-global firms to continue increasing their sales and to expand and upgrade their product line, which in turn increases their chances of remaining independent. The data also show that if the firms prefer to merge with another company, they are in a better position if they do not acquire any other firms beforehand. Finally, our data show that although the majority of born-global companies can continue operations if they survived the first decade, they are not highly successful on the measures of growth and shareholder wealth. One of the recommendations of this study is that for maturing, technology-based, born-global companies to remain successful, they must be more aggressive in their M&A strategy than they are at the moment.     

Self-stabilization of dynamic systems assuming only read/write atomicity

Summary Three self-stabilizing protocols for distributed systems in the shared memory model are presented. The first protocol is a mutual-exclusion prootocol for tree structured systems. The second protocol is a spanning tree protocol for systems with any connected communication graph. The thrid protocol is obtianed by use offair protoco combination, a simple technique which enables the combination of two self-stabilizing dynamic protocols. The result protocol is a self-stabilizing, mutualexclusion protocol for dynamic systems with a general (connected) communication graph. The presented protocols improve upon previous protocols in two ways: First, it is assumed that the only atomic operations are either read or write to the shared memory. Second, our protocols work for any connected network and even for dynamic network, in which the topology of the network may change during the excution. Shlomi Dolev received his B.Sc. in Civil Engineering and B.A. in Computer Science in 1984 and 1985, and his M.Sc. and Ph.D. in computer Sciene in 1989 and 1992 from the Technion Israel Institute of Technology. He is currently a post-dotoral fellow in the Department of Computer Science at Texas A & M Univeristy. His current research interests include the theoretical aspects of distributed computing and communcation networks. Amos Israeli received his B.Sc. in Mathematics and Physics from Hebrew University in 1976, and his M.Sc. and D.Sc. in Computer Science from the Weizmann Institute in 1980 and the Technion in 1985, respectively. Currently he is a sensior lecturer at the Electrical Engineering Department at the Technion. Prior tot his he was a postdoctoral fellow at the Aiken Computation Laboratory at harvard. His research interests are in Parellel and Distributed Computing and in Robotics. In particular he has worked on the design and analysis of Wait-Free and Self-Stabilizing distributed protocols. Shlomo Moran received his B.Sc. and D.Sc. degrees in matheamtics from Technion, Israel Institute of Technology, Haifa, in 1975 and 1979, respectively. From 1979 to 1981 he was assistant professors and a visiting research specialist at the University of Minnesota, Minneapolis. From 1981 to 1985 he was a senior lecturer at the Department of Computer Science. Technion, and from 1985 to 1986 he visted at IBM Thoas J. Watson Research Center, Yorktown Heights. From 1986 to 1993 he was an associated professor at the Department of Computer Science, Technin. in 1992–3 he visited at AT & T Bell Labs at Murray Hill and at Centrum voor Wiskunde en Informatica, Amsterdam. From 1993 he is a full professor at the Department of Computer Science, Technion. His researchinterests include distributed algorithm, computational complexity, combinatorics and grapth theory.Part of this research was supported in part by Technion V.P.R. Funds — Wellner Research Fund, and by the Foundation for Research in Electronics, Computers and Communictions, administrated by the Israel Academy of Sciences and Humanities.