Bounded LTL Model Checking with Stable Models

In this paper bounded model checking of asynchronous concurrent systems is introduced as a promising application area for answer set programming. As the model of asynchronous systems a generalisation of communicating automata, 1-safe Petri nets, are used. It is shown how a 1-safe Petri net and a requirement on the behaviour of the net can be translated into a logic program such that the bounded model checking problem for the net can be solved by computing stable models of the corresponding program. The use of the stable model semantics leads to compact encodings of bounded reachability and deadlock detection tasks as well as the more general problem of bounded model checking of linear temporal logic. Correctness proofs of the devised translations are given, and some experimental results using the translation and the Smodels system are presented.Comment: 32 pages, to appear in Theory and Practice of Logic Programmin

An Entailment Relation for Reasoning on the Web

Reasoning on the Web is receiving an increasing attention because of emerging fields such as Web adaption and Semantic Web. Indeed, the advanced functionalities striven for in these fields call for reasoning capabilities. Reasoning on the Web, however, is usually done using existing techniques rarely fitting the Web. As a consequence, additional data processing like data conversion from Web formats (e.g. XML or HTML) into some other formats (e.g. classical logic terms and formulas) is often needed and aspects of the Web (e.g. its inherent inconsistency) are neglected. This article first gives requirements for an entailment tuned to reasoning on the Web. Then, it describes how classical logic’s entailment can be modified so as to enforce these requirements. Finally, it discusses how the proposed entailment can be used in applying logic programming to reasoning on the Web

Theory of the Half-Polarized Quantum Hall States

We report a theoretical analysis of the half-polarized quantum Hall states observed in a recent experiment. Our numerical results indicate that the ground state energy of the quantum Hall $\nu= 2/3$ and $\nu= 2/5$ states versus spin polarization has a downward cusp at half the maximal spin polarization. We map the two-component fermion system onto a system of excitons and describe the ground state as a liquid state of excitons with non-zero values of exciton angular momentum.Comment: 4 pages (RevTeX), 3 figures (PostScript), added reference

Impact of reindeer grazing on ground-dwelling Carabidae and Curculionidae assemblages in Lapland

Reindeer Rangifer tarandus L. grazing shapes forest vegetation, microclimate, and soil respiration in Lapland, especially due to grazing on lichens (Cladina). We studied how these changes and their magnitude affect ground-dwelling species of beetle families Carabidae (predators) and Curculionidae (herbivores), by using pitfall traps to collect invertebrates from pairs of grazed and ungrazed study plots over a wide range of site types. Changes in abundance, composition, richness and diversity of beetle assemblage were tested in relation to magnitude of the impacts on vegetation. The species compositions of Carabidae and Curculionidae differed between grazed and ungrazed plots in all sites. The relative difference between grazed and ungrazed plots in the number of individuals increased linearly with the impact of reindeer on vegetation cover. Carabid beetles, as a family, were more common in grazed plots in all sites. Curculionid beetles were more common in ungrazed plots in the birch dominated sites. This difference was mainly due to the species that feeds on deciduous leaves. In the pine dominated sites with high Cladina cover and more changes in ground vegetation, the number of curculionids feeding on conifers was higher in grazed plots. Species richness and diversity (H’) of both families were higher in grazed plots. Of the total 27 species, 11 were found only in grazed plots, while not a single species was found only in ungrazed plots. The relative difference between plots in diversity and evennes (H’/H’max) had humped response to the difference in Cladina cover. The diversity values were greater in grazed plots at the intermediate levels of grazing impact, and only in sites with very low or extremely high Cladina cover difference was the diversity higher in ungrazed plots. The response of beetle diversity resembled the hypotheses suggested for the relationship between grazing and vegetation diversity: greatest positive effect at intermediate grazing intensity and negative effects at unproductive sites

Surface Instabilities and Magnetic Soft Matter

We report on the formation of surface instabilities in a layer of thermoreversible ferrogel when exposed to a vertical magnetic field. Both static and time dependent magnetic fields are employed. Under variations of temperature, the viscoelastic properties of our soft magnetic matter can be tuned. Stress relaxation experiments unveil a stretched exponential scaling of the shear modulus, with an exponent of beta=1/3. The resulting magnetic threshold for the formation of Rosensweig-cusps is measured for different temperatures, and compared with theoretical predictions by Bohlius et. al. in J. Phys.: Condens. Matter., 2006, 18, 2671-2684.Comment: accepted to Soft Matte

Theory of Incompressible States in a Narrow Channel

We report on the properties of a system of interacting electrons in a narrow channel in the quantum Hall effect regime. It is shown that an increase in the strength of the Coulomb interaction causes abrupt changes in the width of the charge-density profile of translationally invariant states. We derive a phase diagram which includes many of the stable odd-denominator states as well as a novel fractional quantum Hall state at lowest half-filled Landau level. The collective mode evaluated at the half-filled case is strikingly similar to that for an odd-denominator fractional quantum Hall state.Comment: 4 pages, REVTEX, and 4 .ps file

Optical Spectroscopy of X-Mega targets in Carina Nebula : III. The multiple system Tr 16-104 (≡CPD -59° 2603)

We discuss the orbital elements of the multiple system Tr 16-104 which is usually believed to be a member of the open cluster Trumpler 16 in the Carina complex. We show that Tr 16-104 could be a hierarchical triple system consisting of a short-period (2.15 d) eclipsing O7 V+O9.5 V binary bound to a B0.2 IV star. Our preliminary orbital solution of the third body indicates that the B star most probably describes an eccentric orbit with a period of ∼285 or ∼1341 d around the close binary. Folding photometric data from the literature with our new ephemerides, we find that the light curve of the close binary exhibits rather narrow eclipses indicating that the two O stars must be well inside their Roche lobes. Our analysis of the photometric data yields a lower limit on the inclination of the orbit of the close binary of i≥77°. The stellar radii and luminosities of the O7 V and O9.5 V stars are significantly smaller than expected for stars of this spectral type. Our results suggest that Tr 16-104 lies at a distance of the order of 2.5 kpc and support a fainter absolute magnitude for zero-age main-sequence O stars than usually adopted. We find that the dynamical configuration of Tr 16-104 corresponds to a hierarchical system that should remain stable provided that it suffers no strong perturbation. Finally, we also report long-term temporal variations of high-velocity interstellar Ca ii absorptions in the line of sight towards Tr 16-104.Facultad de Ciencias Astronómicas y Geofísica

The DLV System for Knowledge Representation and Reasoning

This paper presents the DLV system, which is widely considered the state-of-the-art implementation of disjunctive logic programming, and addresses several aspects. As for problem solving, we provide a formal definition of its kernel language, function-free disjunctive logic programs (also known as disjunctive datalog), extended by weak constraints, which are a powerful tool to express optimization problems. We then illustrate the usage of DLV as a tool for knowledge representation and reasoning, describing a new declarative programming methodology which allows one to encode complex problems (up to $\Delta^P_3$-complete problems) in a declarative fashion. On the foundational side, we provide a detailed analysis of the computational complexity of the language of DLV, and by deriving new complexity results we chart a complete picture of the complexity of this language and important fragments thereof. Furthermore, we illustrate the general architecture of the DLV system which has been influenced by these results. As for applications, we overview application front-ends which have been developed on top of DLV to solve specific knowledge representation tasks, and we briefly describe the main international projects investigating the potential of the system for industrial exploitation. Finally, we report about thorough experimentation and benchmarking, which has been carried out to assess the efficiency of the system. The experimental results confirm the solidity of DLV and highlight its potential for emerging application areas like knowledge management and information integration.Comment: 56 pages, 9 figures, 6 table

Colilert-menetelmän verifiointi sosiaali- ja terveysministeriön asetuksen 461/2000 mukaisiin koliformisten bakteerien ja Escherichia coli -bakteerin tutkimuksiin Suomessa

Colilert -18 Quanti-Tray -menetelmä (IDEXX Laboratories

Sairauspoissaolotarpeen määrittäminen : Kyselytutkimus lääkäreille

Kelan tutkimusosasto ja Suomen Lääkäriliitto toteuttivat vuonna 2014 lääkäreille kohdistetun kyselyn, jonka tarkoituksena on kartoittaa lääkäreiden näkemyksiä ja kokemuksia sairauspoissaoloihin liittyvistä käytännöistä ja kehittämistarpeista. Kysely perustuu vuonna 2012 Ruotsissa tehtyyn kyselyyn. Vastaava kysely toteutettiin myös Norjassa. Kysymykset on muokattu kunkin maan järjestelmään sopiviksi. Kyselylomake lähetettiin 8 867 lääkärille loppuvuodesta 2014, ja siihen saattoi vastata joko paperisella tai sähköisellä lomakkeella. Vastausprosentti oli 34,8. Rakenteeltaan aineisto edusti perusjoukkoa, joskin työterveyshuolto oli hieman yliedustettuna. Lääkärit pitivät julkisen sektorin palvelujen saatavuutta keskeisenä syynä sairauspoissaolojen pitkittymiseen. Myös vajaakuntoisten työntekijöiden työssä jaksamista tukevien toimenpiteiden saatavuus vaikutti sairauspoissaolojen kirjoittamiseen. Kelalta toivottiin enemmän palautetta lääkärien omasta toiminnasta. Lääkärien osaamisen kehittämistarpeet korostuivat erityisesti terveyskeskuksissa, mutta koulutusta tarvitsevien osuus on varsin suuri muillakin toimintasektoreilla. Lääkärit toivoivat laajasti, erikoistumisalasta tai toimipaikasta riippumatta, vähintäänkin joitakin sairauksia koskevia kansallisia suosituksia sairauspoissaolojen kestosta. Nykyisiä käytettävissä olevia ohjeita ja suosituksia monet lääkärit pitivät tärkeinä. Työterveyslääkärit erottuivat monissa kohdin omaksi ryhmäkseen. He näyttävät hallitsevan työkyvyn ja sairauspoissaolon tarpeen arviointiin liittyvät tehtävät parhaiten. Suomalaiset lääkärit kokivat ruotsalaisia ja norjalaisia perusterveydenhuollon lääkäreitä vähemmän ongelmia sairauspoissaoloon liittyvissä asioissa. Tutkimuksen perusteella annetuissa suosituksissa esitetään puuttumista jatkohoidon ja kuntoutukseen pääsyn viiveisiin, työkyvyn arviointiin liittyvän koulutuksen lisäämistä, sairauspoissaolotarpeen siirtämistä enemmän työterveyshuollon vastuulle sekä sairauspoissaolojen kestoa koskevien suositusten laatimista ainakin joistakin sairauksista