Broadcast Disks with Polynomial Cost Functions

In broadcast disks systems, information is broadcasted in a shared medium. When a client needs an item from the disk, it waits until that item is broadcasted. Broadcast disks systems are particularly attractive in settings where the potential customers have a highly-asymmetric communication capabilities, i.e., receiving is significantly cheaper than transmitting. This is the case with satellite networks, mobile hosts in wireless networks, and Teletext system.The fundamental algorithmic problem for such systems is to determine the broadcast schedule based on the demand probability of items, and the cost incurred to the system by clients waiting. The goal is to minimize the mean access cost of a random client. Typically, it was assumed that the access cost is proportional to the waiting time. In this paper, we ask what are the best broadcast schedules for access costs which are arbitrary polynomials in the waiting time. These may serve as reasonable representations of reality in many cases, where the patience of a client is not necessarily proportional to its waiting time.We present an asymptotically optimal algorithm for a fractional model, where the bandwidth may be divided to allow for fractional concurrent broadcasting. This algorithm, besides being justified in its own right, also serves as a lower bound against which we test known discrete algorithms. We show that the Greedy algorithm has the best performance in most cases. Then we show that the performance of other algorithms deteriorate exponentially with the degree of the cost polynomial and approaches the fractional solution for sub-linear cost. Finally, we study the quality of approximating the greedy schedule by a finite schedule.     

A decision support system for inventory management in high research & development environment

Inventory management is being discussed recently as one of the key elements for survival and success in the production industry today. Little efforts were made to solve inventory problems in the Hi R&D environment.

In this paper, a prototype of a Microcomputer Based Decision Support is introduced to support decisions for managing Hi R&D inventories. The decisions involve timing and scheduling of purchased components, as well as classification of those items.     

Metaphor understanding and accessing conceptual schema: Reply to Gibbs (1992).

R. W. Gibbs (see record 1992-42479-001) argued that metaphoric expressions may reflect preexisting conventional metaphoric mappings in long-term memory. The class-inclusion model, in contrast, focuses on conceptual structures that are constructed and accessible in working memory during metaphor comprehension. The authors agree that prestored metaphoric mappings may be available, but they may not be accessible and hence not used in any given context. The authors point out problems in identifying those metaphorical mappings that may be relevant to a given metaphoric expression and suggest that conceptual metaphors may not be identifiable until after a metaphor has been interpreted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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

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)     

Manganese mobilization and enrichment during soil aquifer treatment (SAT) of effluents, the Dan Region Sewage Reclamation Project (Shafdan), Israel

The composition of groundwater reclaimed from tertiary soil aquifer treatment systems reflects the dynamic processes taking place in the subsurface, between the infiltration basin and the production wells. At the end of year 2000, following more than a decade of operation, high Mn concentrations (2 micromol L(-1) < or = Mn < or = 40 micromol L(-1)) appeared in the reclaimed effluents of the Dan Region Sewage Reclamation Project (Shafdan), Israel. A mass balance indicates that the high Mn excess originated from the aquifer rocks, most likely following reduction of sedimentary Mn-oxides under suboxic conditions. The subsequent adsorption of the Mn2+ results in a slow Mn2+ front that advances in the direction of groundwater flow only when all the Mn2+ exchangeable sites are saturated. A retardation factor obtained from two independent estimates based on a simple reduction-adsorption-advection model yields a value of about 10. This explains the delayed appearance of the high Mn concentrations at a distance of only -500 m from the infiltration basin.     

Aspects of the biology of Labeo cylindricus (Pisces: cyprinidae) in Lake Baringo,Kenya

Aspects of the biology of Labeo cylindricus from Lake Baringo were investigated, based on experimental beach seining and gillnetting between August and October 2007. The length–weight relationship indicated the species exhibited positive allometric growth (b = 3.7083), with a condition factor (K) of 0.84 ± 0.0298 S.D. Males dominated fish catches, with an adult sex ratio of males/females of 1:1.7. The fish length‐at‐50% maturity (Lm50) was 127.7 and 126.1 mm total length (TL) for males and females, respectively. Fish age and growth were determined from sagittal otoliths considered to be from the young‐of‐the‐year. Clear circuli observed in the otoliths were used to determine fish age in days. Validation by oxytetracycline marking indicated that a single growth increment (1.1 ± 0.1 SE) is formed daily on fish otoliths. Fish length (TL mm) was correlated significantly with age (in days), TL = 1.398 Age + 26.523 (r² = 0.91). Fish growth was subsequently estimated to be 1.398 mm day^?1. The weights and ages (in days) of fish exhibited a significant (P < 0.05) power relationship defined by the equation: W = 0.0003 Age^2.5804 (r² = 0.88). The results of this study provide parameters that, if appropriately monitored, can be used to predict responses of fish populations in Lake Baringo and elsewhere to human interventions (exploitation) and natural environmental change.