Smooth Scheduling under Variable Rates or the Analog-Digital Confinement Game

This work considers non-terminating scheduling problems in which a system of multiple resources serves clients having variable needs. The system has m identical resources and n clients; in each time slot each resource may serve at most one client; in each such slot t each client γ has a rate, a real number ρ _γ (t), that specifies his needs in this slot. The rates satisfy the restriction ∑ _γ ρ _γ (t)≤m for any slot t. Except of this restriction, the rates can vary in arbitrary fashion. (This contrasts most prior works in this area in which the rates of the clients are constant.) The schedule is required to be smooth as follows: a schedule is Δ -smooth if for all time intervals I the absolute difference between the amount of service received by each client γ to his nominal needs of ∑ _t∈I ρ _γ (t) is less than Δ. Our objective are online schedulers that produce Δ-smooth schedules where Δ is a small constant which is independent of m and n. Our paper constructs such schedulers; these are the first online Δ-smooth schedulers, with a constant Δ, for clients with arbitrarily variable rates in a single or multiple resource system. Furthermore, the paper also considers a non-concurrent environment in which there is an additional restriction that each client is served at most once in each time slot; it presents the first online smooth schedulers for variable rates under this restriction. The above non-concurrent restriction is crucial in some applications (e.g., CPU scheduling). It has been pointed out that this restriction “adds a surprising amount of difficulty” to the scheduling problem. However, this observation was never formalized and, of course, was never proved. Our paper formalizes and proves some aspects of this observation. Another contribution of this paper is the introduction of a complete information, two player game called the analog-digital confinement game. In such a game pebbles are located on the real line; the two players, the analog player and the digital player, take alternating turns and each one, in his turn, moves some of the pebbles; the digital player moves the pebbles backwards by discrete distances while the analog player moves the pebbles forward by analog distances; the aim of the analog player is to cause one pebble (or more) to escape a pre-defined real interval while the aim of the digital player is to confine the pebbles into the interval. We demonstrate that this game is a convenient framework to study the general question of how to approximate an analog process by a digital one. All the above scheduling results are established via this game. In this derivation, the pebbles represent the clients, the analog player generates the needs of the clients and the digital player generates the schedule. Dedicated to the memory of Professor Shimon Even for his inspiration and encouragement     

Prevalence of Clostridium botulinum in food raw materials used in REPFEDs manufactured in France

Food raw materials used in refrigerated processed foods of extended durability (REPFEDs) manufactured in France were surveyed for Clostridium botulinum types A, B and E using PCR-Enzyme-linked Immunosorbent assay (PCR-ELISA) and mouse bioassay for detection respectively of cells and toxins in enrichment broth. Portions of 25 to 50 g of food were analysed. A total of 8 out of the 102 samples of fish and shellfish, 12 out of the 143 samples of meat and poultry, 1 out of the 62 samples of aroma, sauce and gravy, 4 out of the 25 samples of thickening agents, 3 out of the 26 samples of dehydrated dairy ingredients, and none of the 65 samples of spices, herbs and dehydrated mushroom were positive for C. botulinum in PCR-ELISA, i.e., 6.6% of all the samples tested. The 28 positive samples comprised 10 type A, 10 type B, 4 with both types A and B, and 4 undetermined by PCR typing. No sample positive for type E was detected. Of the 28 samples positive in PCR-ELISA, 15 were also positive in the mouse bioassay. The MPN count was between 1 and 3 C. botulinum/kg of food, which is similar to or in the lower range of values reported in the literature.     

An implementation of precompiled headers

Compilation time can be improved by precompiling interfaces so that the compiler can avoid processing unreferenced declarations. However, in C-based languages precompiling a header is difficult because a header can have several meanings depending on the context in which it is included. We present an ad hoc solution to this problem, and give the results of our precompilation strategy, which improved compile times by 25 to 65 per cent over compilation without precompiled headers.     

The Economics of the Television Market for Theatrical Movies

The new bargaining strategy of network bidding for feature films before their theatrical release is a logical extension of the networks' activities in the regular TV programming market.     

Mos: A multicomputer distributed operating system

This paper describes the goals and the internal structure of MOS, a Multicomputer distributed Operating System. MOS is a general-purpose time-sharing operating system which makes a cluster of loosely connected independent homogeneous computers behave as a single-machine UNIX system. The main goals of the system include network transparency, decentralized control, site autonomy and dynamic process migration. The main objective in the design of the system was to reduce the complexity of the system, while maintaining good performance. The internal structure of the system can be characterized by modularity, a high degree of information hiding, hierarchical organization and remote procedure calls.     

Theoretical and computational aspects of 2-D inverse profiling

The authors discuss two techniques for solving two-dimensional (2D) inverse scattering problems by parameterizing the scattering configuration, and determining the optimum value of the parameters by minimizing a cost function involving the known scattered-field data. The computation of the fields in each estimated configuration is considered as an auxiliary problem. To improve the efficiency of these computations, the CGFFT iterative scheme is combined with a special extrapolation procedure that is valid for problems with a varying physical parameter such as frequency, angle of incidence, or contrast. Further, they analyze the dynamic range and the resolution of linearized schemes. To obtain an acceptable resolution for an object with a large contrast with respect to the surrounding medium, multiple-frequency information is used. Finally, the availability of a fast-forward solver was an incentive to consider nonlinear optimization. In particular, the authors use a quasi-Newton algorithm at only twice the computational cost of the distorted-wave Born iterative scheme     

Biphasic Decay Kinetics of Fecal Bacteria in Surface Water Not a Density Effect

The decay of fecal bacteria in surface water often follows a biphasic pattern with the apparent first-order rate constant relatively high during a first phase and lower in a second one. This could be the result of population heterogeneity in resistance due to various mechanisms (different strains, genetically or nongenetically differentiated cells, different growth or cell cycle stage, clumping, hardening), or the specific decay rate could be directly or indirectly affected by the cell density (e.g., quorum sensing). All these mechanisms can theoretically produce a biphasic decay pattern and are consistent with the literature. However, they are fundamentally different and lead to different behavior of mechanistic total maximum daily load models, so identifying the correct mechanism is important. This technical note presents the results of a study aimed at determining if a density effect is involved. Laboratory decay experiments with pure strain Escherichia coli cells in phosphate buffer were conducted over a range of initial densities. The results show that the rate constant changes after a certain time, rather than at a certain density, which is inconsistent with a density effect. As the experiments were performed with a pure strain, the resistant fraction cannot be attributed to a different strain. Further research is needed to identify the mechanism responsible for the population heterogeneity.     

Mechanisms of action of docosahexaenoic acid in the nervous system

Abtract This review describes (from both the animal and human literature) the biological consequences of losses in nervous system docosahexaenoate (DHA). It then concentrates on biological mechanisms that may serve to explain changes in brain and retinal function. Brief consideration is given to actions of DHA as a nonesterified fatty acid and as a docosanoid or other bioactive molecule. The role of DHA-phospholipids in regulating G-protein signaling is presented in the context of studies with rhodopsin. It is clear that the visual pigment responds to the degree of unsaturation of the membrane lipids. At the cell biological level, DHA is shown to have a protective role in a cell culture model of apoptosis in relation to its effects in increasing cellular phosphatidylserine (PS); also, the loss of DHA leads to a loss in PS. Thus, through its effects on PS, DHA may play an important role in the regulation of cell signaling and in cell proliferation. Finally, progress has been made recently in nuclear magnetic responance studies to delineate differences in molecular structure and order in biomembranes due to subtle changes in the degree of phospholipid unsaturation.     

Two cases of bilateral congenital cholesteatoma--usual and unusual presentations

We generated mice harboring germline mutations in which the enhancer element located 9 kb 3' of the immunoglobulin kappa light chain gene (3'E kappa) was replaced either by a single loxP site (3'E kappa delta) or by a neomycin resistance gene (3'E kappa N). Mice homozygous for the 3'E(kappa delta) mutation had substantially reduced numbers of kappa-expressing B cells and increased numbers of lambda-expressing B cells accompanied by decreased kappa versus lambda gene rearrangement. In these mutant mice, kappa expression was reduced in resting B cells, but was normal in activated B cells. The homozygous 3'E(kappa)N mutation resulted in a similar but more pronounced phenotype. Both mutations acted in cis. These studies show that the 3'E(kappa) is critical for establishing the normal kappa/lambda ratio, but is not absolutely essential for kappa gene rearrangement or, surprisingly, for normal kappa expression in activated B cells. These studies also imply the existence of additional regulatory elements that have overlapping function with the 3'E(kappa) element.