On the Hardness of SAT with Community Structure

Recent attempts to explain the effectiveness of Boolean satisfiability (SAT) solvers based on conflict-driven clause learning (CDCL) on large industrial benchmarks have focused on the concept of community structure. Specifically, industrial benchmarks have been empirically found to have good community structure, and experiments seem to show a correlation between such structure and the efficiency of CDCL. However, in this paper we establish hardness results suggesting that community structure is not sufficient to explain the success of CDCL in practice. First, we formally characterize a property shared by a wide class of metrics capturing community structure, including "modularity". Next, we show that the SAT instances with good community structure according to any metric with this property are still NP-hard. Finally, we study a class of random instances generated from the "pseudo-industrial" community attachment model of Gir\'aldez-Cru and Levy. We prove that, with high probability, instances from this model that have relatively few communities but are still highly modular require exponentially long resolution proofs and so are hard for CDCL. We also present experimental evidence that our result continues to hold for instances with many more communities. This indicates that actual industrial instances easily solved by CDCL may have some other relevant structure not captured by the community attachment model.Comment: 23 pages. Full version of a SAT 2016 pape

A EFICIÊNCIA NA GESTÃO DO JUDICIíRIO COMO HIPÓTESE DE SUPERAÇÃO DO PROBLEMA DA MOROSIDADE NA ATIVIDADE JURISDICIONAL

The delay in the judicial activity is a problem to be solved. Notably, in Brazil, the solutions to this problem have been sought in procedural reforms in the legislation. When researching the causes of delays in judicial activity, it appears that the causes are related, much more, the administrative actions of the judiciary than with procedural technique. Not adopting this theoretical common sense, the present study sought to solve the problem by means the application of principle of efficiency in administrative activities within the judiciary. Based on literature reviews, data analysis and foreign experience, it was concluded the wisdom of focusing on improving the management of the judiciary. In this sense, confirmed the application of administrative efficiency in the support activities of the judiciary as a solution to the problem of delays in judicialactivity.Tem-se como um problema a ser resolvido a morosidade na atividade jurisdicional. Notadamente, no Brasil, as soluções para a morosidade tem sido buscadas em reformas na legislação processual. Ao se pesquisar as causas da morosidade na atividade jurisdicional, verifica-se que essas se ligam muito mais a atuação administrativa do Judiciário do que a técnica processual. Por isso, fugindo desse senso comum teórico, o presente trabalho buscou a solução do problema da morosidade pela via da aplicação do princí­pio da eficiência nas atividades administrativas desenvolvidas no âmbito do Judiciário. Com base em revisões bibliográficas, análise de dados e de experiências estrangeiras, concluiu-se o acerto de se focar na melhoria da gestão do Judiciário. Nesse sentido, confirmou-se a aplicação da eficiência administrativa nas atividades-meio do Judiciário como solução para o problema da morosidade na atividadejurisdicional

Myelination induces axonal hotspots of synaptic vesicle fusion that promote sheath growth

Myelination of axons by oligodendrocytes enables fast saltatory conduction. Oligodendrocytes are responsive to neuronal activity, which has been shown to induce changes to myelin sheaths, potentially to optimize conduction and neural circuit function. However, the cellular bases of activity-regulated myelination in vivo are unclear, partly due to the difficulty of analyzing individual myelinated axons over time. Activity-regulated myelination occurs in specific neuronal subtypes and can be mediated by synaptic vesicle fusion, but several questions remain: it is unclear whether vesicular fusion occurs stochastically along axons or in discrete hotspots during myelination and whether vesicular fusion regulates myelin targeting, formation, and/or growth. It is also unclear why some neurons, but not others, exhibit activity-regulated myelination. Here, we imaged synaptic vesicle fusion in individual neurons in living zebrafish and documented robust vesicular fusion along axons during myelination. Surprisingly, we found that axonal vesicular fusion increased upon and required myelination. We found that axonal vesicular fusion was enriched in hotspots, namely the heminodal non-myelinated domains into which sheaths grew. Blocking vesicular fusion reduced the stable formation and growth of myelin sheaths, and chemogenetically stimulating neuronal activity promoted sheath growth. Finally, we observed high levels of axonal vesicular fusion only in neuronal subtypes that exhibit activity-regulated myelination. Our results identify a novel "feedforward" mechanism whereby the process of myelination promotes the neuronal activity-regulated signal, vesicular fusion that, in turn, consolidates sheath growth along specific axons selected for myelination

AS TECNOLOGIAS DIGITAIS DA INFORMAÇÃO E COMUNICAÇÃO NO TRABALHO DOCENTE: PRÁTICAS NO ENSINO MÉDIO DE UMA ESCOLA PÚBLICA

O presente trabalho buscou investigar as ações desenvolvidas por quatro professores do Ensino Médio de uma escola pública de Campo Grande. O referido estudo teve como objetivo descrever, analisar e avaliar os procedimentos do trabalho docente associados às tecnologias digitais da informação e comunicação (TDICs)

AS TECNOLOGIAS DIGITAIS DA INFORMAÇÃO E COMUNICAÇÃO NO TRABALHO DOCENTE: PRÁTICAS NO ENSINO MÉDIO DE UMA ESCOLA PÚBLICA

O presente trabalho buscou investigar as ações desenvolvidas por quatro professores do Ensino Médio de uma escola pública de Campo Grande. O referido estudo teve como objetivo descrever, analisar e avaliar os procedimentos do trabalho docente associados às tecnologias digitais da informação e comunicação (TDICs)

Nutritional Status among Portuguese and Turkish Older Adults Living in the Community: Relationships with Sociodemographic, Health and Anthropometric Characteristics

Malnutrition is widespread among older adults, and its determinants may differ between countries. We compared Portuguese and Turkish non-institutionalized older adults regarding nutritional status, sociodemographic, health and anthropometric characteristics and studied the relationships between nutritional status and those characteristics. This cross-sectional study analyzed data from 430 Portuguese and 162 Turkish non-institutionalized older adults regarding sociodemographics, health conditions, the Mini-Nutritional Assessment (MNA-FF) and anthropometry. Turkish older adults were more likely to be malnourished or at risk of malnutrition and had lower average BMI but a higher calf circumference. A higher proportion of the Portuguese sample had tooth loss, diabetes, hypertension, oncologic diseases, kidney diseases, osteoarticular problems or eye problems, while less had anemia. A better nutritional status (higher MNA-FF score) was found among the Portuguese, males, people using dentures, those without tooth loss, hypertension, cardiovascular diseases, anemia or oncological diseases and was related to younger age, higher BMI and a higher calf circumference. Malnutrition and its risk were higher among older adults from Turkey, despite Portuguese older adults presenting a higher prevalence of chronic diseases. Being female, older age, tooth loss, hypertension, anemia, CVD or oncological disorders and having a lower BMI or CC were associated with higher rates of malnutrition among older adults from Portugal and Turkey

Interpolation in variable exponent spaces

In this paper we study both real and complex interpolation in the recently introduced scales of variable exponent Besov and Triebel–Lizorkin spaces. We also take advantage of some interpolation results to study a trace property and some pseudodifferential operators acting in the variable index Besov scale

Dynamical tunneling in molecules: Quantum routes to energy flow

Dynamical tunneling, introduced in the molecular context, is more than two decades old and refers to phenomena that are classically forbidden but allowed by quantum mechanics. On the other hand the phenomenon of intramolecular vibrational energy redistribution (IVR) has occupied a central place in the field of chemical physics for a much longer period of time. Although the two phenomena seem to be unrelated several studies indicate that dynamical tunneling, in terms of its mechanism and timescales, can have important implications for IVR. Examples include the observation of local mode doublets, clustering of rotational energy levels, and extremely narrow vibrational features in high resolution molecular spectra. Both the phenomena are strongly influenced by the nature of the underlying classical phase space. This work reviews the current state of understanding of dynamical tunneling from the phase space perspective and the consequences for intramolecular vibrational energy flow in polyatomic molecules.Comment: 37 pages and 23 figures (low resolution); Int. Rev. Phys. Chem. (Review to appear in Oct. 2007