The effect of integration time on fluctuation measurements: calibrating an optical trap in the presence of motion blur

Dynamical instrument limitations, such as finite detection bandwidth, do not simply add statistical errors to fluctuation measurements, but can create significant systematic biases that affect the measurement of steady-state properties. Such effects must be considered when calibrating ultra-sensitive force probes by analyzing the observed Brownian fluctuations. In this article, we present a novel method for extracting the true spring constant and diffusion coefficient of a harmonically confined Brownian particle that extends the standard equipartition and power spectrum techniques to account for video-image motion blur. These results are confirmed both numerically with a Brownian dynamics simulation, and experimentally with laser optical tweezers.Comment: 12 pages, 6 figures, revtex4; published in Optics Express. http://www.opticsinfobase.org/abstract.cfm?URI=oe-14-25-1251

Towards defining semantic foundations for purpose-based privacy policies

We define a semantic model for purpose, based on which purpose-based privacy policies can be meaningfully expressed and enforced in a business system. The model is based on the intuition that the purpose of an action is determined by its situation among other inter-related actions. Actions and their relationships can be modeled in the form of an action graph which is based on the business processes in a system. Accordingly, a modal logic and the corresponding model checking algorithm are developed for formal expression of purpose-based policies and verifying whether a particular system complies with them. It is also shown through various examples, how various typical purpose-based policies as well as some new policy types can be expressed and checked using our model

Distributed Computing Systems and Checkpointing

This paper examines the performance of synchronous checkpointing in a distributed computing environment with and without load redistribution. Performance models are developed, and optimum checkpoint intervals are determined. The analysis extends earlier work by allowing for multiple nodes, state dependent checkpoint intervals, and a performance metric which is coupled with failure-free performance and the speedup functions associated with implementation of parallel algorithms. Expressions for the optimum checkpoint intervals for synchronous checkpointing with and without load redistribution are derived and the results are then used to determine when load redistribution is advantageous

Multicomputer Checkpointing

This paper examines the performance of synchronous checkpointing in a distributed computing environment with and without load redistribution. Performance models are developed, and optimum checkpoint intervals are determined. We extend earlier work by allowing for multiple nodes, state dependent checkpoint intervals, and a performance metric which is coupled with failure-free performance. We show that the optimum checkpoint intervals in the presence of load redestribution has a numerical solution in all cases and a closed form in many reasonable cases. These new results are then used to determine when performance can benefit load redistribution

CATHETER ASSOCIATED LEIFSONIA AQUATICA INFECTION

Objective: This is a case report of catheter-related infection caused by Leifsonia aquatica in a hemodialysis patient. Leifsonia aquatica is not a commonly isolated bacterium and not much is known about the virulence, pathogenesis of infection or choice of treatment. Methods: A case report of a 65 years old man who presented with chills and rigors during hemodialysis via an internal jugular catheter. Results: Leifsonia aquatica was isolated from the patient’s blood culture. The organism grew on conventional media and was identified using analytical profile index (API) Coryne. The patient was successfully treated with two weeks of ceftriaxone and the catheter was removed. Conclusion: Leifsonia aquatica is an aquatic bacterium capable of causing infection in the immunocompromised host and its pathogenicity is related to its ability to form biofilms. Treatment based on antimicrobial susceptibility results and removal of the catheter is necessary for a patient’s recovery

Load and Communications Balancing on Multiprocessor Logic Simulation Engines

The problem considered in this paper is to find an assignment of logic components to processors which will achieve logic simulation speed-ups approaching the ideal for large processor populations. This problem becomes particularly important when a significant portion of the speed-up expected from logic simulation engines is attributed to load sharing (as opposed to obtaining speed-up by employing specialized hardware to carry out specific tasks associated with the simulation process such as event queue manipulation or function evaluation). Our research considers this problem for a particular multiprocessor simulation architecture for which a performance model has bene developed. The model is parameterized on the basis of workload characteristics, architecture design parameters, and load (processing and communication) distribution. Workload characteristics were derived from actual VLSI circuit simulations. An approach to the component assignment problem is presented and evaluated using this data. The circuits that we are considering have component populations in the tens and hundreds of thousands. Since the optimal component assignment problem is NP-complete, a heuristic assignment is considered and its performance compared against a simple random assignment algorithm (i.e. components are assigned to processors such that each processor is chosen with equal probability). The random assignment method, though simple, is shown analytically to have large communication requirements even for the small number of processors (e.g. five). This approach therefore limits the number of processors which can be effectively applied towards speeding up the simulation process through exploitation of computational parallelism. The heuristic examined in this paper attempts to improve on the random assignment method by reducing the communication volume while maintaining the degree of parallelism in the random method. Results show that for tens of processors and circuit sizes in the tens of thousands, the heuristic can reduce the message volume in the benchmark circuits by a factor of between 2 and 4