On a common circle: Natural scenes and Gestalt rules

To understand how the human visual system analyzes images, it is essential to know the structure of the visual environment. In particular, natural images display consistent statistical properties that distinguish them from random luminance distributions. We have studied the geometric regularities of oriented elements (edges or line segments) present in an ensemble of visual scenes, asking how much information the presence of a segment in a particular location of the visual scene carries about the presence of a second segment at different relative positions and orientations. We observed strong long-range correlations in the distribution of oriented segments that extend over the whole visual field. We further show that a very simple geometric rule, cocircularity, predicts the arrangement of segments in natural scenes, and that different geometrical arrangements show relevant differences in their scaling properties. Our results show similarities to geometric features of previous physiological and psychophysical studies. We discuss the implications of these findings for theories of early vision.

Toward rules for 1:1 polyamide:DNA recognition

Polyamides composed of four amino acids, imidazole (Im), pyrrole (Py), hydroxypyrrole (Hp), and β-alanine (β), are synthetic ligands that form highly stable complexes in the minor groove of DNA. Although specific pairing rules within the 2:1 motif can be used to distinguish the four Watson⋅Crick base pairs, a comparable recognition code for 1:1 polyamide:DNA complexes had not been described. To set a quantitative baseline for the field, the sequence specificities of Im, Py, Hp, and β for the four Watson⋅Crick base pairs were determined for two polyamides, Im-β-ImPy-β-Im-β-ImPy-β-Dp (1, for Im, Py, and β) and Im-β-ImHp-β-Im-β-ImPy-β-Dp (2, for Hp), in a 1:1 complex within the DNA sequence context 5′-AAAGAGAAGAG-3′. Im residues do not distinguish G,C from A,T but bind all four base pairs with high affinity. Py and β residues exhibit ≥10-fold preference for A,T over G,C base pairs. The Hp residue displays a unique preference for a single A⋅T base pair with an energetic penalty.

An A-DNA triplet code: thermodynamic rules for predicting A- and B-DNA.

The ability to predict macromolecular conformations from sequence and thermodynamic principles has long been coveted but generally has not been achieved. We show that differences in the hydration of DNA surfaces can be used to distinguish between sequences that form A- and B-DNA. From this, a "triplet code" of A-DNA propensities was derived as energetic rules for predicting A-DNA formation. This code correctly predicted > 90% of A- and B-DNA sequences in crystals and correlates with A-DNA formation in solution. Thus, with our previous studies on Z-DNA, we now have a single method to predict the relative stability of sequences in the three standard DNA duplex conformations.

Supplementary Information. Undecidability of the spectral gap

This is the supplementary information associated to the article: T.S. Cubitt, D. Perez-Garcia, M.M. Wolf, Undecidability of the spectral gap, Nature 528, 207-211 (2015), doi:10.1038/nature16059

Expansible Computable Aggregation Rules

The aggregation operator have been considered from a computable point of view. The important condition that the computation is friendly when portions of data are inserted o deleted to the list of values to aggregate is considered.

Gráfico de controle para monitoramento da razão da demanda e mão de obra em retaguarda de serviços no setor bancário.

O monitoramento da razão Z de duas variáveis através de gráfico de controle tem sido um tema recentemente explorado na literatura. Para analisar mais o assunto, o estudo avalia a eficiência e viabilidade de aplicação dessa ferramenta como suporte na tomada de decisão para gerenciamento de capacidade de mão de obra de retaguarda (doravante mencionado como Backoffice) de serviço de empresa do setor bancário. Tradicionalmente, gráficos de controle tem sido utilizados para monitorar o processo produtivo de manufaturas, mas recentemente tem sido adotado para monitoramento de alguns serviços. Apesar de ainda seguir muitos conceitos pioneiros na manufatura, a atividade do setor de serviços apresenta suas particularidades como, por exemplo, a impossibilidade de gerar estoque. Assim, a necessidade de adequar seus recursos à demanda torna-se essencial, sendo fundamental a gestão de controles e sua urgência para que possa reagir rapidamente em caso de variação de demanda e adequar sua capacidade. Em um cenário de restrição de recursos, planejar é crucial para evitar desperdícios e garantir eficiência. O objetivo deste estudo é apresentar o gráfico de controle como ferramenta para monitorar a razão de duas variáveis aleatórias: a demanda e a mão de obra em Backoffice de serviço em um banco. Nesse trabalho, gráfico de controle de Shewhart tradicional e gráfico de controle de Shewhart com regras suplementares são analisados e os resultados obtidos confirmam a possibilidade de utilização da ferramenta de gráficos de controle para o gerenciamento e adequação de mão de obra para atender a demanda. O monitoramento da razão (demanda/ mão de obra) ajudará o gestor a alocar adequadamente o time (mão de obra) de acordo com a demanda e a capacidade produtiva. Como contribuição, o estudo avalia o comportamento da razão Z = X/Y em situação de alta variabilidade da variável X e baixa variabilidade da variável Y .

Fail-Safe Testing of Web Applications

This dissertation introduces an approach to generate tests to test fail-safe behavior for web applications. We apply the approach to a commercial web application. We build models for both behavioral and mitigation requirements. We create mitigation tests from an existing functional black box test suite by determining failure type and points of failure in the test suite and weaving required mitigation based on weaving rules to generate a test suite that tests proper mitigation of failures. A genetic algorithm (GA) is used to determine points of failure and type of failure that needs to be tested. Mitigation test paths are woven into the behavioral test at the point of failure based on failure specific weaving rules. A simulator was developed to evaluate choice of parameters for the genetic algorithm. We showed how to tune the fitness function and performed tuning experiments for GA to determine what values to use for exploration weight and prospecting weight. We found that higher defect densities make prospecting and mining more successful, while lower mitigation defect densities need more exploration. We compare efficiency and effectiveness of the approach. First, the GA approach is compared to random selection. The results show that the GA performance was better than random selection and that the approach was robust when the search space increased. Second, we compare the GA against four coverage criteria. The results of comparison show that test requirements generated by a genetic algorithm (GA) are more efficient than three of the four coverage criteria for large search spaces. They are equally effective. For small search spaces, the genetic algorithm is less effective than three of the four coverage criteria. The fourth coverage criteria is too weak and unable to find all defects in almost all cases. We also present a large case study of a mortgage system at one of our industrial partners and show how we formalize the approach. We evaluate the use of a GA to create test requirements. The evaluation includes choice of initial population, multiplicity of runs and a discussion of the cost of evaluating fitness. Finally, we build a selective regression testing approach based on types of changes (add, delete, or modify) that could occur in the behavioral model, the fault model, the mitigation models, the weaving rules, and the state-event matrix. We provide a systematic method by showing the formalization steps for each type of change to the various models.

Staying in the Delaware Corporate Governance Lane: Fee Shifting Bylaws and a Legislative Reaffirmation of the Rules of the Road

The Delaware legislature has taken steps towards the adoption of amendments to the Delaware General Corporation Law (DGCL) that would prohibit fee shifting provisions in the articles and bylaws. The language in the legislative proposal, however, addresses fee shifting provisions only in the context of "internal corporate claims." Some have raised concerns that this language would allow for fee shifting provisions that applied to other types of actions, including at least some cases brought under the securities laws. This piece suggests that in fact the Delaware General Corporation Law already prohibits the adoption of bylaws and certificate provisions that apply to causes of action unrelated to internal corporate claims. As a result, there was no reason for the Delaware legislature to expressly bar fee shifting provisions in these types of actions.

Representing Clients in the Marijuana Industry: Navigating State and Federal Rules

As the number of states legalizing medicinal and recreational marijuana increases and marijuana emerges as a growing lawful industry, lawyers find themselves in an awkward position. In most states, lawyers who represent clients in the marijuana industry risk discipline for assisting clients in the commission of a (federal) crime. Even in jurisdictions like Colorado, where the rules of professional conduct have been amended to permit lawyers to assist clients who comply with marijuana state laws, lawyers who are admitted to practice in federal courts risk being disciplined by these tribunals for assisting clients in the commission of a crime pursuant to the courts’ local rules of conduct. This short article explores the thorny issue of navigating state and federal rules of professional conduct while representing clients in the marijuana industry.

Supplementary Material: Analysis of the Connecting Zone Between Consecutive Sections in Distillation Columns Covering Multiple Feeds, Products and Heat Transfer Stages

Supplementary Material: J.A. REYES-LABARTA, M.D. SERRANO and A. MARCILLA. ANALYSIS OF THE CONNECTING ZONE BETWEEN CONSECUTIVE SECTIONS IN DISTILLATION COLUMNS COVERING MULTIPLE FEEDS, PRODUCTS AND HEAT TRANSFER STAGES. Latin American Applied Research an International Journal of Chemical Engineering. 2014, vol. 44(4), 307-312 (http://www.laar.uns.edu.ar/indexes/artic_v4404/44_04_307.pdf)