Optimal Algorithmic Cooling of Spins

Algorithmic cooling (AC) is a recent spin-cooling approach that employs entropy compression methods in open systems. AC reduces the entropy of spins on suitable molecules beyond Shannon's bound on the degree of entropy compression by reversible manipulations. Remarkably, AC makes use of thermalization, a generally destructive facet of spin systems, as an integral part of the cooling scheme. AC is capable of cooling spins to very low temperatures and provides significant cooling for molecules containing as few as 5–7 spins. Application of AC to slightly larger molecules could lead to breakthroughs in high-sensitivity NMR spectroscopy in the near future. Furthermore, AC may be germane to the development of scalable NMR quantum computers. We introduce here a new practicable algorithm, “PAC3”, and several new exhaustive cooling algorithms, such as the Tribonacci and k-bonacci algorithms. In particular, we present the “all-bonacci” algorithm, which appears to reach the maximal degree of cooling obtainable by the optimal AC approach. AC is potentially beneficial for NMR-derived biomedical applications, which involve bio-molecules with isotope enrichments, such as ¹³ C- and ¹⁵ N-labeled amino acids. We briefly survey AC experiments, including a recent 3-spin experiment in which Shannon's bound was bypassed. The difficulties associated with cooling molecules bearing a greater number of spins are explained. Finally, the potential of selected cooling algorithms (practicable, exhaustive, and optimal algorithms) is illustrated with regard to a highly relevant bio-medical target— ¹³ C-labeled glucose.     

Using the KBTA method for inferring computer and network security alerts from time-stamped,raw system metrics

In this study, we propose a new approach for detecting previously unencountered instances of known classes of malicious software based on their temporal behavior. In the proposed approach, time-stamped security data are continuously monitored within the target computer system or network and then processed by the knowledge-based temporal abstraction (KBTA) methodology. Using KBTA, continuously measured data (e.g., the number of running processes) and events (e.g., installation of a software) are integrated with a security-domain, temporal-abstraction knowledge-base (i.e., a security ontology for abstracting meaningful patterns from raw, time-oriented security data), to create higher-level, time-oriented concepts and patterns, also known as temporal abstractions. Automatically-generated temporal abstractions can be monitored to detect suspicious temporal patterns. These patterns are compatible with a set of predefined classes of malware as defined by a security expert employing a set of time and value constraints. The new approach was applied for detecting worm-related malware using two different ontologies. Evaluation results demonstrated the effectiveness of the new approach. The approach can be used for detecting other types of malware by updating the security ontology with new definitions of temporal patterns.     

Combat flow: Military, political, and ethical dimensions of subjective well-being in war.

The theory of flow argues that subjective well-being results from absorption in an activity that strikes a good balance between challenges and skills. This absorption has been termed flow. Such absorption is often reported in combat situations, in which it contributes both to the subjective well-being and to the efficiency of soldiers. This article suggests that combat flow may have been central to military training and military performance throughout history. The study of combat flow could therefore shed new light on military history and form the basis for the development of new training techniques. The article simultaneously probes the ethical and political implications of manipulating the subjective well-being of soldiers in such a way. It cautions scholars of flow and subjective well-being that they should be aware of the ethical and political implications of their studies and warns against the dangerous political results of equating subjective well-being with happiness. The article further calls for greater cooperation between psychologists and historians in the study of well-being. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

CAPSUL: A constraint-based specification of repeating patterns in time-oriented data

We use a constraint-based language to specify repeating temporal patterns. The Constraint-based Pattern Specification Language (CAPSUL) is simple to use, but allows a wide variety of patterns to be expressed. This paper describes in detail the syntax of CAPSUL, including its layers of abstraction and four types of constraints. We also discuss the semantics of CAPSUL, including the concept of interference between patterns and the expressive power of the language. We have implemented CAPSUL in a temporal-abstraction system called Résumé, and used it in a graphical knowledge-acquisition tool to acquire domain-specific knowledge from experts about patterns to be found in large databases. We summarize the results of preliminary experiments using the pattern-specification and pattern-detection tools on data about patients who have cancer and have been seen at the Rush Presbyterian/St. Luke's Medical Center. This revised version was published online in June 2006 with corrections to the Cover Date.     

Expert maintenance systems in telecommunication networks

Our survey of some 40 network maintenance expert systems reveals theri main shortcoming, which is the difficulty to acquire troubleshooting knowledge both when initializing the expert system and after its deployment. Additionally, the state-of-the-art troubleshooting expert systems do not optimize troubleshooting cost. We present theAO ^* algorithm to generate a network troubleshooting expert system which minimizes the expected troubleshooting cost and learns better troubleshooting techniques during its operation.     

High-Order Embedded Finite Difference Schemes for Initial Boundary Value Problems on Time Dependent Irregular Domains

This paper considers a family of spatially discrete approximations, including boundary treatment, to initial boundary value problems in evolving bounded domains. The presented method is based on the Cartesian grid embedded Finite-Difference method, which was initially introduced by Abarbanel and Ditkowski (ICASE Report No. 96-8, 1996; and J. Comput. Phys. 133(2), 1997) and Ditkowski (Ph.D. thesis, Tel Aviv University, 1997), for initial boundary value problems on constant irregular domains. We perform a comprehensive theoretical analysis of the numerical issues, which arise when dealing with domains, whose boundaries evolve smoothly in the spatial domain as a function of time. In this class of problems the moving boundaries are impenetrable with either Dirichlet or Neumann boundary conditions, and should not be confused with the class of moving interface problems such as multiple phase flow, solidification, and the Stefan problem. Unlike other similar works on this class of problems, the resulting method is not restricted to domains of up to 3-D, can achieve higher than 2nd-order accuracy both in time and space, and is strictly stable in semi-discrete settings. The strict stability property of the method also implies, that the numerical solution remains consistent and valid for a long integration time. A complete convergence analysis is carried in semi-discrete settings, including a detailed analysis for the implementation of the diffusion equation. Numerical solutions of the diffusion equation, using the method for a 2nd and a 4th-order of accuracy are carried out in one dimension and two dimensions respectively, which demonstrates the efficacy of the method. This research was supported by the Israel Science Foundation (grant No. 1362/04).     

Positive Tertiary Appraisals and Posttraumatic Stress Disorder in U.S. Male Veterans of the War in Vietnam: The Roles of Positive Affirmation, Positive Reformulation, and Defensive Denial.

A 70.9% majority of the U.S. male veterans in a nationwide sample appraised the impact of their service in Vietnam on their present lives as mainly positive. A substantial minority, 41.7%, judged the effects to be highly salient. With controls on level of exposure to war-zone stressors measured with data from military records, the valence and salience of these appraisals are investigated in relation to posttraumatic stress disorder (PTSD) and other indicators of wartime and postwar functioning. The results are consistent with the hypothesis that mainly positive tertiary appraisals are affirmations of successful wartime and postwar adaptation rather than defensive denials related to maladaptive outcomes. The possibility that mainly positive tertiary appraisals also contribute to successful postwar adaptation is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A structural approach for PoP geo-location

Inferring PoP level maps is gaining interest due to its importance to many areas, e.g., for tracking the Internet evolution and studying its properties. In this paper we introduce a novel structural approach to automatically generate large scale PoP level maps using traceroute measurement from multiple locations. The PoPs are first identified based on their structure, and are then assigned a location using information from several geo-location databases. We discuss the tradeoffs in this approach and provide extensive validation details. The generated maps can be widely used for research, and we provide some possible directions.