Optimal certifying algorithms for linear and lattice point feasibility in a system of UTVPI constraints

This thesis is concerned with the design and analysis of time-optimal and spaceoptimal, certifying algorithms for checking the linear and lattice point feasibility of a class of constraints called Unit Two Variable Per Inequality (UTVPI) constraints. In a UTVPI constraint, there are at most two non-zero variables per constraint, and the coefficients of the non-zero variables belong to the set {lcub}+1, --1{rcub}. These constraints occur in a number of application domains, including but not limited to program verification, abstract interpretation, and operations research. As per the literature, the fastest known certifying algorithm for checking lattice point feasibility in UTVPI constraint systems ([1]), runs in O( m n + n2 log n) time and O(n2) space, where m represents the number of constraints and n represents the number of variables in the constraint system. In this paper, we design and analyze new algorithms for checking the linear feasibility and the lattice point feasibility of UTVPI constraints. Both of the presented algorithms run in O( m[.]n) time and O(m + n) space. Additionally they are certifying in that they produce satisfying assignments in the event that they are presented with feasible instances and refutations in the event that they are presented with infeasible instances. The importance of providing certificates cannot be overemphasized, especially in mission-critical applications. Our approaches for both the linear and the lattice point feasibility problems in UTVPI constraints are fundamentally different from existing approaches for these problems (as described in the literature), in that our approaches are based on new insights on using well-known inference rules

Analyzing Satisfiability and Refutability in Selected Constraint Systems

This dissertation is concerned with the satisfiability and refutability problems for several constraint systems. We examine both Boolean constraint systems, in which each variable is limited to the values true and false, and polyhedral constraint systems, in which each variable is limited to the set of real numbers R in the case of linear polyhedral systems or the set of integers Z in the case of integer polyhedral systems. An important aspect of our research is that we focus on providing certificates. That is, we provide satisfying assignments or easily checkable proofs of infeasibility depending on whether the instance is feasible or not. Providing easily checkable certificates has become a much sought after feature in algorithms, especially in light of spectacular failures in the implementations of some well-known algorithms. There exist a number of problems in the constraint-solving domain for which efficient algorithms have been proposed, but which lack a certifying counterpart. When examining Boolean constraint systems, we specifically look at systems of 2-CNF clauses and systems of Horn clauses. When examining polyhedral constraint systems, we specifically look at systems of difference constraints, systems of UTVPI constraints, and systems of Horn constraints. For each examined system, we determine several properties of general refutations and determine the complexity of finding restricted refutations. These restricted forms of refutation include read-once refutations, in which each constraint can be used at most once; literal-once refutations, in which for each literal at most one constraint containing that literal can be used; and unit refutations, in which each step of the refutation must use a constraint containing exactly one literal. The advantage of read-once refutations is that they are guaranteed to be short. Thus, while not every constraint system has a read-once refutation, the small size of the refutation guarantees easy checkability

New Results on Cutting Plane Proofs for Horn Constraint Systems

In this paper, we investigate properties of cutting plane based refutations for a class of integer programs called Horn constraint systems (HCS). Briefly, a system of linear inequalities A * x >= b is called a Horn constraint system, if each entry in A belongs to the set {0,1,-1} and furthermore there is at most one positive entry per row. Our focus is on deriving refutations i.e., proofs of unsatisfiability of such programs using cutting planes as a proof system. We also look at several properties of these refutations. Horn constraint systems can be considered as a more general form of propositional Horn formulas, i.e., CNF formulas with at most one positive literal per clause. Cutting plane calculus (CP) is a well-known calculus for deciding the unsatisfiability of propositional CNF formulas and integer programs. Usually, CP consists of a pair of inference rules. These are called the addition rule (ADD) and the division rule (DIV). In this paper, we show that cutting plane calculus is still complete for Horn constraints when every intermediate constraint is required to be Horn. We also investigate the lengths of cutting plane proofs for Horn constraint systems

Shortening day length as a previously unrecognized selective pressure for early breeding in a bird with long parental care

Several different selective pressures have been suggested to explain an intense competition for early return to breeding grounds in birds. In this study we hypothesized that shortening day length during summer months may constitute additional selective force acting towards early breeding in avian species with long parental care. To test this hypothesis, we studied time budget and foraging activities of early-nesting and late-nesting white storks Ciconia ciconia from the Central-European population. We found that duration and distance of foraging trips increased significantly over the course of the reproductive season. The relative frequency of foraging trips increased at the expense of other activities, such as resting, plumage maintenance, and nest maintenance. Mean daily foraging duration increased with increasing day length in the early part of the season, with 0.68 h of foraging per individual per 13.16 h of day length in mid-April increasing to 7.42 h of foraging per individual during solstice (16.61 h of day length). Afterwards, mean foraging duration continued increasing in spite of decreasing day length, reaching 11.63 h of foraging per individual per 14.92 h of day length at the end of the season in mid-August, when storks were forced to continue foraging after sunset in order to meet energy requirements of fledglings. The results suggest that shortening day length during summer months may constitute a serious time constraint on food delivery rates to offspring for late-breeding pairs of white storkEuropean Social Fund and the Polish National Budget in the D-RIM project of the Human Capital Programm

Sense of taste in patients after cochlear implantation-preliminary study

Background: Taste is the leading sense in how we determine the quality of consumed food. Proper gustatory sensation largely determines the well-being and health of an organism, and this affects their quality of life.Objectives: The aim of the present study was to estimate the risk of early taste disorders following implantation surgery. Methods: Twenty patients underwent a taste test before, 1 day after, and 1 month after cochlear implantation. The taste sensations of sweet, sour, salty, and bitter were determined. Results: Statistical analysis showed no significant differences (p > 0.05) between individual tests among the entire study group. After dividing the respondents into smoking (n=6) and non-smoking (n=14) groups, only a weak correlation (p =0.043) was found between the results of the first and second examination in the smoker group. However, a statistically significant decrease in the number of saline-sensitive (p<0.001) and acid-sensitive (p = 0.042) subjects was observed. Conclusion: These findings suggest that people after a cochlear implant may have transient taste disorders. Taste disorder called dysgeusia may be an early complication after the implantation procedure contributing to deterioration of patients quality of life. Keywords: Sense of taste; taste disorders; cochlear implant surgery; quality of life, partial deafness treatment

Susceptibility to risky sexual behaviours in the polish population aged 15-63

Frequent involvement in risky sexual behaviors among members of society is a threat to their health. It’s also a social problem, as it increases the risk of spreading STDs and unwanted pregnancies. The aim of the study was to check the susceptibility to risky sexual behaviors in the Polish population aged 15-63. The research method was an original online questionnaire. A total of 294 responses were obtained from people of different gender, age, place of residence and level of education. The results were then statistically analyzed. 84% of respondents had undergone sexual initiation. The remaining respondents were excluded from further study. The average age of initiation was 18.2 years. 73% of respondents claim to never use condoms during oral sex. 22% of respondents use other methods instead of condoms. In the past 12 months, 21% of respondents had more than 1 sexual partner and 36% often had sex after drinking alcohol. 60% of respondents have never tested for STDs, and only 5% do it regularly when changing sexual partners. Subjects of concern are: large proportion of respondents who do not protect themselves during oral sex, a small number of respondents who regularly get tested for STDs, and a significant group of people who declare that they frequently have sex under the influence of alkohol

Stabilization of spin states of an open system : bichromatic driving of resonance transitions in NV ensembles in diamond

We apply a laser and two nearly degenerate microwave fields upon an ensemble of nitrogen-vacancy centers in diamond and observe magnetic resonance structures with two-component, composite shapes of nested Lorentzians with different widths. One component of them undergoes regular power-broadening, whereas the linewidth of the other one becomes power-independent and undergoes field-induced stabilization. We show that the observed width stabilization is a general phenomenon that results from competition between coherent driving and non-conservation of populations that occur in open systems. The phenomenon is interpreted in terms of specific combinations of state populations that play the role of bright and dark states

Effective Thermal Conductivity of SrBi4_4Ti4_4O15_{15}-La0.7_{0.7}Sr0.3_{0.3}MnO3_3 Oxide composite: Role of Particle Size and Interface Thermal Resistance

We present a novel approach to reduce the thermal conductivity ($\kappa$) in thermoelectric composite materials using acoustic impedance mismatch and the Debye model. Also, the correlation between interface thermal resistance (R$_{int}$) and the particle size of the dispersed phase on the k of the composite is discussed. In particular, the $\kappa$ of an oxide composite which consists of a natural superlattice Aurivillius phase (SrBi$_4$Ti$_4$O$_{15}$) as a matrix and perovskite (La$_{0.7}$Sr$_{0.3}$MnO$_3$) as a dispersed phase is investigated. A significant reduction in the $\kappa$ of composite, even lower than the $\kappa$ of the matrix when the particle size of La$_{0.7}$Sr$_{0.3}$MnO$_3$ is smaller than the Kapitza radius (a$_K$) is observed, depicting that R$_{int}$ dominates for particle size lower than a$_K$ due to increased surface to volume ratio. The obtained results have the potential to provide new directions for engineering composite thermoelectric systems with desired thermal conductivity and promising in the field of energy harvesting.Comment: 21 pages, 8 Figures, 5 Table

An annotaded checklist of the Aphids (Hemiptera: Aphidomorpha) of Poland

The paper presents a comprehensive compilation of 764 taxa (species and subspecies), distributed over 167 genera, belonging to 17 subfamilies, three families and three superfamilies of Aphidomorpha recorded to date from Poland. The systematic positions of 19 taxa have been revised in accordance with recent changes in nomenclature. The presence in the Polish aphidofauna of Drepanosiphum oregonensis and Coloradoa huculaki, previously included without any distribution data in checklists of Polish aphids, has been confirmed. One species Sitobion (Sitobion) alopecuri is recognized as being new to Poland. At least 44 species (6% of local fauna of Aphidomorpha) are alien to Poland; among them 11 species collected from plants imported or cultivated in indoor conditions are listed