Linear objects: Logical processes with built-in inheritance

We present a new framework for amalgamating two successful programming paradigms: logic programming and object-oriented programming. From the former, we keep the delarative reading of programs. From the latter, we select two crucial notions: (i) the ability for objects to dynamically change their internal state during the computation; (ii) the structured representation of knowledge, generally obtained via inheritance graphs among classes of objects. We start with the approach, introduced in concurrent logic programming languages, which identifies objects with proof processes and object states with arguments occurring in the goal of a given process. This provides a clean, side-effect free account of the dynamic behavior of objects in terms of the search tree—the only dynamic entity in logic programming languages. We integrate this view of objects with an extension of logic programming, which we call Linear Objects, based on the possibility of having multiple literals in the head of a program clause. This contains within itself the basis for a flexible form of inheritance, and maintains the constructive property of Prolog of returning definite answer substitutions as output of the proof of non-ground goals. The theoretical background for Linear Objects is Linear Logic, a logic recently introduced to provide a theoretical basis for the study of concurrency. We also show that Linear Objects can be considered as constructive restriction of full Classical Logic. We illustrate the expressive power of Linear Objects compared to Prolog by several examples from the object-oriented domain, but we also show that it can be used to provide elegant solutions for problems arising in the standard style of logic programming.     

The genuine short GRB 090227B and the disguised by excess GRB 090510

GRB 090227B and GRB 090510, traditionally classified as short gamma-ray Bursts (GRBs), indeed originate from different systems. For GRB 090227B we inferred a total energy of the e ⁺ e ^? plasma \(E_{e^ + e^ - }^{tot} \) = (2.83 ± 0.15) × 10⁵³ erg, a baryon load of B = (4.1 ± 0.05) × 10^?5, and a CircumBurstMedium (CBM) average density 〈n _CBM〉 = (1.90 ± 0.20) × 10^?5 cm^?3. From these results we have assumed the progenitor of this burst to be a symmetric neutron stars (NSs) merger with masses m = 1.34 M_⊙, radii R = 12.24 km. GRB 090510, instead, has \(E_{e^ + e^ - }^{tot} \) = (1.10 ± 0.06) × 10⁵³ erg, B = (1.45 ± 0.28) × 10^?3, implying a Lorentz factor at transparency of Γ = (6.7 ± 1.7) × 10², which are characteristic of the long GRB class, and a very high CBM density, 〈n _CBM〉 = (1.85 ± 0.14) × 10³ cm^?3. The joint effect of the high values of Γ and of 〈n _CBM〉 compresses in time and “inflates” in intensity in an extended afterglow, making appear GRB 090510 as a short burst, which we here define as “disguised short GRB by excess” occurring an overdense region with 10³ cm^?3.     

Patterning of soft polydimethylsiloxane elastomers using plasma etching

Soft polydimethylsiloxane (PDMS) elastomers spin coated on silicon wafers are patterned using plasma etching. The elastomers are formed by mixing vinyl‐terminated PDMS (prepolymer) and crosslinker containing hydride sites. The elastomers are made softer by adding either excess prepolymer, excess crosslinker, or swelling agent. The different elastomers were etched using reactive ion etching, an old and well established processing technology in the microelectronic and MEMS industry. The etch rate and profiles of the etched surfaces were dependent on the process pressure. The dependence was different for the different elastomers. It was found that at low pressure, the etch rate was dependent on the shear modulus. At high pressures, the etch rate was dependent on the chemical composition of the elastomer. The results for the swollen elastomers were different from those for the nonswollen elastomers. The etch rate was lower and the profiles of the etched cavities were different. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Level of viral antigen in blood leucocytes from cattle acutely infected with bovine viral diarrhoea virus

Blood samples from 24 calves undergoing experimental acute infection with a non-cytopathogenic bovine viral diarrhoea virus (BVDV) were examined for viral antigen in peripheral leucocytes with an enzyme-linked immunosorbent assay (ELISA), and for presence of virus in blood plasma in a cell culture assay. With the antigen ELISA, low positive values were detected in leucocytes sampled on days 3-4 from two of eight animals inoculated intranasally, and on days 11-13 from three of 16 animals inoculated intramuscularly. From 22 of the animals, low titres of BVDV were detected in blood plasma obtained 2-9 days after inoculation. All other samples, drawn between 2 and 21 days after inoculation, were negative for viral antigen. All animals seroconverted 3-4 weeks after inoculation, some after having shown mild and transient signs of disease.     

A nonlinear functional approach to LFT model validation

Model validation provides a useful means of assessing the ability of a model to account for a specific experimental observation, and has application to modeling, identification and fault detection. In this paper, we consider a new approach to the model validation problem by deploying quadratic functionals, and more generally nonlinear functionals, to specify noise and dynamical perturbation sets. Specifically, we consider a general linear fractional transformation framework for the model structure, and use constraints involving nonlinear functional inequalities to specify model non-linearities and unknown perturbations, and characteristics of noise and disturbance signals. Sufficient conditions for invalidation of such models are provided in terms of semidefinite programming problems.     

A multi-start local search heuristic for ship scheduling—a computational study

We present a multi-start local search heuristic for a typical ship scheduling problem. A large number of initial solutions are generated by an insertion heuristic with random elements. The best initial solutions are improved by a local search heuristic that is split into a quick and an extended version. The quick local search is used to improve a given number of the best initial solutions. The extended local search heuristic is then used to further improve some of the best solutions found. The multi-start local search heuristic is compared with an optimization-based solution approach with respect to computation time and solution quality. The computational study shows that the multi-start local search method consistently returns optimal or near-optimal solutions to real-life instances of the ship scheduling problem within a reasonable amount of computation time.     

Static analysis of Linear Logic programming

Linear Logic is gaining momentum in computer science because it offers a unified framework and a common vocabulary for studying and analyzing different aspects of programming and computation. We focus here on models where computation is identified with proof search in the sequent system of Linear Logic. A proof normalization procedure, called “focusing”, has been proposed to make the problem of proof search tractable. Correspondingly, there is a normalization procedure mapping formulae of Linear Logic into a syntactic fragment of that logic, calledLinLog, where the focusing normalization for proofs can be most conveniently expressed. In this paper, we propose to push this compilation/normalization process further, by applying abstract interpretation and partial evaluation techniques to (focused) proofs inLinLog. These techniques provide information concerning the evolution of the computational resources (formulae) during the execution (proof construction). The practical outcome that we expect from this theoretical effort is the definition of a general tool for statically analyzing and reasoning about the runtime behavior of programs in frameworks where computations can be accounted for in terms of proof search in Linear Logic.     

Trends of perfluorinated alkyl substances in herring gull eggs from two coastal colonies in northern Norway: 1983-2003

The present study reports on concentrations, patterns, and temporal trends (1983, 1993, and 2003) of 16 perfluorinated alkyl substances (PFAS) in whole eggs of herring gulls (Larus argentatus) from two geographically isolated colonies in northern Norway. Perfluorooctane sulfonate (PFOS) was the predominant PFAS in all eggs with mean concentrations up to 42 ng/g wet weight (ww) in samples from 2003. Perfluorohexane sulfonate (PFHxS) and perfluorodecane sulfonate (PFDcS) were found at concentrations several orders of magnitude lower than PFOS. The general accumulation profile of perfluorocarboxylates (PFCAs) in herring gull eggs was characterized by high proportions of odd and long carbon (C) chain length compounds in which perfluoroundecanoate (C11) and perfluorotridecanoate (C13) dominated with mean concentrations up to 4.2 and 2.8 ng/g ww, respectively. In both colonies PFOS concentrations in eggs showed a nearly 2-fold significant increase from 1983 to 1993, followed by a leveling off up to 2003. A comparable trend was found for PFHxS, whereas PFDcS was found to increase also between 1993 and 2003. PFCA concentrations showed marked significant increases during 1983-1993 associated with either a weak rise post-1993 (C8- to C11-PFCAs), although nonsignificant, or leveling off (C12- and C13-PFCAs). However, the composition of individual PFCAs (C8 to C15) to the summed concentrations of those eight PFCAs highly differed between the colonies and sampling years investigated. Present results suggest that direct and indirect local- and/or remote-sourced inputs (atmospheric and waterborne) of PFCAs have changed over the last two decades in these two coastal areas of Northern Norway.