A Hybrid Intuitionistic Logic: Semantics and Decidability

An intuitionistic, hybrid modal logic suitable for reasoning about distribution of resources was introduced by Jia and Walker. The modalities of the logic allow validation of properties in a particular place, in some place and in all places. We give a sound and complete Kripke semantics for the logic extended with disjunctive connectives. The extended logic can be seen as an instance of Hybrid IS5. We also give a sound and complete birelational semantics, and show that it enjoys the finite model property: if a judgement is not valid in the logic, then there is a finite birelational counter-model. Hence, we prove that the logic is decidable

A Distributed Kripke Semantics

An intuitionistic, hybrid modal logic suitable for reasoning about distribution of resources was introduced in [10]. We extend the Kripke semantics of intuitionistic logic, enriching each possible Kripke state with a set of places, and show that this semantics is both sound and complete for the logic. In the semantics, resources of a distributed system are interpreted as atoms, and placement of atoms in a possible state corresponds to the distribution of the resources. The modalities of the logic allow us to validate properties in a particular place, in some place and in all places. We extend the logic with disjunctive connectives, and refine our semantics to obtain soundness and completeness for extended logic. The extended logic can be seen as an instance of Hybrid IS5 [2, 18]

A reduced semantics for deciding trace equivalence using constraint systems

Many privacy-type properties of security protocols can be modelled using trace equivalence properties in suitable process algebras. It has been shown that such properties can be decided for interesting classes of finite processes (i.e., without replication) by means of symbolic execution and constraint solving. However, this does not suffice to obtain practical tools. Current prototypes suffer from a classical combinatorial explosion problem caused by the exploration of many interleavings in the behaviour of processes. M\"odersheim et al. have tackled this problem for reachability properties using partial order reduction techniques. We revisit their work, generalize it and adapt it for equivalence checking. We obtain an optimization in the form of a reduced symbolic semantics that eliminates redundant interleavings on the fly.Comment: Accepted for publication at POST'1

Deep bore well water level fluctuations in the Koyna region, India: the presence of a low order dynamical system in a seismically active environment

Water level fluctuations in deep bore wells in the vicinity of seismically active Koyna region in western India provides an opportunity to understand the causative mechanism underlying reservoir-triggered earthquakes. As the crustal porous rocks behave nonlinearly, their characteristics can be obtained by analysing water level fluctuations, which reflect an integrated response of the medium. A Fractal dimension is one such measure of nonlinear characteristics of porous rock as observed in water level data from the Koyna region. It is inferred in our study that a low nonlinear dynamical system with three variables can predict the water level fluctuations in bore wells

Degradation kinetics of metronidazole and its mutual prodrug with ciprofloxacin: a calorimetric analysis

Calorimetric technique has aroused considerable interest as a versatile tool in pharmaceutical industry and academia to provide useful information about thermodynamic and kinetic aspects of drug molecules. The present paper utilizes this technique to monitor the hydrolytic degradation of metronidazole and its prodrug with ciprofloxacin, i.e. 2-(2-methyl-5-nitroimidazol-1-yl)ethyl-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-7-(1-piperazinyl)-quinoline-3-carboxylate. The synthesis of the present mutual prodrug was envisaged to combine the antiprotozoal and anaerobic antibacterial effects of metronidazole with antibacterial effects of ciprofloxacin. Heat flux microcalorimeter was used to determine the rate of heat evolved during the degradation of the drug and prodrug as a function of concentration, pH and temperature. In terms of enthalpy of hydrolysis the response is exothermic both for drug and prodrug. However, the absolute value of the enthalpy of reaction (ΔrH0) is low for the prodrug. The degradation followed pseudo first order kinetics, showed marked stability at pH 3-7 followed by accelerated hydrolysis at higher pH, characteristic of general acid-base catalysis. The catalytic rate constant for hydrogen ion (kH) and hydroxyl ion (kOH) were found to be 0.413 and 526.1 M-1h-1, respectively, at 318.15 K. The hydrolysis of the prodrug was found to be approximately 50-60 times faster than that of the drug. This may be attributed to the fact that hydrolysis of ester group in prodrug is assisted by keto group on the ciprofloxacin. However, there is no effect of protonation of nitrogen in piperazine ring in ciprofloxacin on the hydrolysis due to the distance from the ester moiety. Keywords: Calorimetry, stability studies, degradation kinetics, ciprofloxacin, metronidazole. International Journal of Biological and Chemical Sciences Vol. 1 (3) 2007: pp.197-21

Qualitative Analysis of Partially-observable Markov Decision Processes

We study observation-based strategies for partially-observable Markov decision processes (POMDPs) with omega-regular objectives. An observation-based strategy relies on partial information about the history of a play, namely, on the past sequence of observations. We consider the qualitative analysis problem: given a POMDP with an omega-regular objective, whether there is an observation-based strategy to achieve the objective with probability~1 (almost-sure winning), or with positive probability (positive winning). Our main results are twofold. First, we present a complete picture of the computational complexity of the qualitative analysis of POMDP s with parity objectives (a canonical form to express omega-regular objectives) and its subclasses. Our contribution consists in establishing several upper and lower bounds that were not known in literature. Second, we present optimal bounds (matching upper and lower bounds) on the memory required by pure and randomized observation-based strategies for the qualitative analysis of POMDP s with parity objectives and its subclasses

Borel Summation of the Derivative Expansion and Effective Actions

We give an explicit demonstration that the derivative expansion of the QED effective action is a divergent but Borel summable asymptotic series, for a particular inhomogeneous background magnetic field. A duality transformation B\to iE gives a non-Borel-summable perturbative series for a time dependent background electric field, and Borel dispersion relations yield the non-perturbative imaginary part of the effective action, which determines the pair production probability. Resummations of leading Borel approximations exponentiate to give perturbative corrections to the exponents in the non-perturbative pair production rates. Comparison with a WKB analysis suggests that these divergence properties are general features of derivative expansions and effective actions.Comment: 18 pp, Revtex, 2 fig

High orders of perturbation theory: are renormalons significant?

According to Lipatov, the high orders of perturbation theory are determined by saddle-point configurations (instantons) of the corresponding functional integrals. According to t'Hooft, some individual large diagrams, renormalons, are also significant and they are not contained in the Lipatov contribution. The history of the conception of renormalons is presented, and the arguments in favor of and against their significance are discussed. The analytic properties of the Borel transforms of functional integrals, Green functions, vertex parts, and scaling functions are investigated in the case of \phi^4 theory. Their analyticity in a complex plane with a cut from the first instanton singularity to infinity (the Le Guillou - Zinn-Justin hypothesis) is proved. It rules out the existence of the renormalon singularities pointed out by t'Hooft and demonstrates the nonconstructiveness of the conception of renormalons as a whole. The results can be interpreted as an indication of the internal consistency of \phi^4 theory.Comment: 28 pages, 8 figures include

Anthropometric factors and breast cancer risk among urban and rural women in South India: a multicentric case–control study

Breast cancer (BC) incidence in India is approximately twice as high in urban women than in rural women, among whom we investigated the role of anthropometric factors and body size. The study was conducted at the Regional Cancer Centre, Trivandrum, and in three cancer hospitals in Chennai during 2002–2005. Histologically confirmed cases (n=1866) and age-matched controls (n=1873) were selected. Anthropometric factors were measured in standard ways. Information on body size at different periods of life was obtained using pictograms. Odds ratios (OR) of BC were estimated through logistic regression modelling. Proportion of women with body mass index (BMI)>25.0 kg/m2, waist size >85 cm and hip size >100 cm was significantly higher among urban than rural women. Risk was increased for waist size >85 cm (pre-menopausal: OR=1.24, 95% CI: 0.96–1.62; post-menopausal: 1.61, 95% CI: 1.22–2.12) and hip size >100 cm (pre-menopausal: OR=1.47, 95% CI: 1.05–2.06; post-menopausal 2.42, 95% CI: 1.72–3.41). Large body size at age 10 (OR=1.75, 95% CI: 1.01–3.03) and increased BMI (OR=1.33, 95% CI: 1.05–1.69 for 25.0–29.9 kg/m2 and OR=1.56, 95% CI: 1.03–2.35 for 30+ kg/m2) were associated with pre-menopausal BC risk. Our data support the hypotheses that increased anthropometric factors are risk factors of BC in India

Nailfold Videocapillaroscopic Features and Other Clinical Risk Factors for Digital Ulcers in Systemic Sclerosis: A Multicenter, Prospective Cohort Study

OBJECTIVE: To identify nailfold videocapillaroscopic and other clinical risk factors for new digital ulcers (DUs) in a 6-month period in patients with systemic sclerosis (SSc), the videoCAPillaroscopy (CAP) study. METHODS: Overall 623 patients with SSc from 59 centers (14 countries) were stratified into two groups: "DU History" and "No-DU History". At enrollment, patients underwent detailed nailfold videocapillaroscopic evaluation and an assessment of demographics, DU status, and clinical and SSc characteristics. Risk factors for developing new DUs were assessed using univariable and multivariable logistic regression analyses. RESULTS: Of the "DU History" group (n = 468), 79.5% were female, the mean age was 54.0 ± 13.7 years, 59.8% had limited cutaneous SSc, and 22% developed a new DU during follow-up. The strongest risk factors for new DUs identified by multivariable logistic regression (MLR) in the "DU History" group included: mean number of capillaries/mm in the middle finger of the dominant hand, number of DUs (0, 1, 2, ≥3), and presence of critical digital ischemia. The receiver operating characteristic area under the curve (ROC-AUC) (95% confidence interval [CI]) of the final MLR model was 0.738 (0.681-0.795). Internal validation through bootstrap generated a ROC-AUC (95% CI) of 0.633 (0.510-0.756). CONCLUSION: This international, prospective study including detailed nailfold videocapillaroscopic evaluation and extensive clinical characterization of patients with SSc identified the mean number of capillaries/mm in the middle finger of the dominant hand, number of DUs and presence of critical digital ischemia at enrollment as risk factors for the development of new DUs. This article is protected by copyright. All rights reserved