358 research outputs found

    Satisfiability in multi-valued circuits

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    Satisfiability of Boolean circuits is among the most known and important problems in theoretical computer science. This problem is NP-complete in general but becomes polynomial time when restricted either to monotone gates or linear gates. We go outside Boolean realm and consider circuits built of any fixed set of gates on an arbitrary large finite domain. From the complexity point of view this is strictly connected with the problems of solving equations (or systems of equations) over finite algebras. The research reported in this work was motivated by a desire to know for which finite algebras A\mathbf A there is a polynomial time algorithm that decides if an equation over A\mathbf A has a solution. We are also looking for polynomial time algorithms that decide if two circuits over a finite algebra compute the same function. Although we have not managed to solve these problems in the most general setting we have obtained such a characterization for a very broad class of algebras from congruence modular varieties. This class includes most known and well-studied algebras such as groups, rings, modules (and their generalizations like quasigroups, loops, near-rings, nonassociative rings, Lie algebras), lattices (and their extensions like Boolean algebras, Heyting algebras or other algebras connected with multi-valued logics including MV-algebras). This paper seems to be the first systematic study of the computational complexity of satisfiability of non-Boolean circuits and solving equations over finite algebras. The characterization results provided by the paper is given in terms of nice structural properties of algebras for which the problems are solvable in polynomial time.Comment: 50 page

    Effectiveness of interventions to improve health behaviours of health professionals : A systematic review

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    Objective To evaluate the effectiveness of interventions designed to improve the health behaviours of health professionals. Design Systematic review. Data sources Database searches: Medline, Cochrane library, Embase and CINAHL. Review methods This systematic review used Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to compare randomised controlled trials of health professionals, published between 2010 and 2021, which aimed to improve at least one health behaviour such as physical activity, diet, smoking status, mental health and stress. Two independent reviewers screened articles, extracted data and assessed quality of studies and reporting. The quality of articles was assessed using the Effective Public Health Practice Project quality assessment tool and the completeness of intervention reporting was assessed. Outcome measures The outcome assessed was change in behaviour between intervention and control groups from baseline to follow-up. Results Nine studies met the eligibility criteria, totalling 1107 participants. Health behaviours targeted were mental health and stress, physical activity, and smoking cessation, physical activity and nutrition. Six interventions observed significant improvements in the health behaviour in the intervention compared with control groups. Seven of the studies selected in person workshops as the mode of intervention delivery. The quality of the included studies was high with 80% (7/9) graded as moderate or strong. Conclusions Although high heterogeneity was found between interventions and outcomes, promising progress has occurred across a variety of health behaviours. Improving reporting and use of theories and models may improve effectiveness and evaluation of interventions. Further investigation is needed to recommend effective strategies. PROSPERO registration number CRD42021238684

    Congruence modularity implies cyclic terms for finite algebras

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    An n-ary operation f : A(n) -> A is called cyclic if it is idempotent and f(a(1), a(2), a(3), ... , a(n)) = f(a(2), a(3), ... , a(n), a(1)) for every a(1), ... , a(n) is an element of A. We prove that every finite algebra A in a congruence modular variety has a p-ary cyclic term operation for any prime p greater than vertical bar A vertical bar

    Mind-mindedness and preschool children’s behavioral difficulties: the moderating role of maternal parenting distress

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    Mind-mindedness (MM) is a caregiver’s tendency to appreciate their infant’s internal mental states. This longitudinal study investigated whether maternal MM (10 months) was linked with children’s later behavioral problems (51 months) and the moderating role of maternal parenting distress (PD; 36 months) in a sample of 91 mother–infant dyads. Appropriate MM comments were coded from video-recorded, semi-structured play interactions between mothers and their infants; PD was obtained from maternal completion of the PD subscale of the Parenting Stress Index – Short Form (PSI-SF); and child internalizing and externalizing behavior problems were gathered from maternal report on the Strengths and Difficulties Questionnaire (SDQ). Moderated regression analyses revealed higher early appropriate MM was associated with significantly fewer internalizing emotional problems at 51 months among mothers with lower PD at 36 months, and higher early appropriate MM was associated with lower conduct problems at 51 months in mothers with higher PD at 36 months. Findings demonstrated the importance of considering nuanced contexts such as at-risk mothers and differential presentations of child difficulties in the analysis of the relationship between MM and child behavioral difficulties and the development of MM interventions

    Live to cheat another day: bacterial dormancy facilitates the social exploitation of beta-lactamases

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    The breakdown of antibiotics by β-lactamases may be cooperative, since resistant cells can detoxify their environment and facilitate the growth of susceptible neighbours. However, previous studies of this phenomenon have used artificial bacterial vectors or engineered bacteria to increase the secretion of β-lactamases from cells. Here, we investigated whether a broad-spectrum β-lactamase gene carried by a naturally occurring plasmid (pCT) is cooperative under a range of conditions. In ordinary batch culture on solid media, there was little or no evidence that resistant bacteria could protect susceptible cells from ampicillin, although resistant colonies could locally detoxify this growth medium. However, when susceptible cells were inoculated at high densities, late-appearing phenotypically susceptible bacteria grew in the vicinity of resistant colonies. We infer that persisters, cells that have survived antibiotics by undergoing a period of dormancy, founded these satellite colonies. The number of persister colonies was positively correlated with the density of resistant colonies and increased as antibiotic concentrations decreased. We argue that detoxification can be cooperative under a limited range of conditions: if the toxins are bacteriostatic rather than bacteridical; or if susceptible cells invade communities after resistant bacteria; or if dormancy allows susceptible cells to avoid bactericides. Resistance and tolerance were previously thought to be independent solutions for surviving antibiotics. Here, we show that these are interacting strategies: the presence of bacteria adopting one solution can have substantial effects on the fitness of their neighbours
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