Mutual diffusivity in binary mixtures of n-heptane with n-hexane isomers

This paper presents a study of the influence of branching in the binary diffusion coefficients of n-heptane+n-hexane isomers, in the liquid state. The measurements have been made with the Taylor dispersion technique, at several compositions, at 283 and 298 K, for the X+n-heptane mixtures, where X=n-hexane, 3-methylpentane, 2, 3-dimethylbutane, and 2, 2-dimethylbutane. The results show a very interesting behavior of the composition dependence of the binary diffusion coefficients, presenting a maximum, for compositions about a molar fraction of n-heptane of 0.5, which increases with the increase in the degree of branching, suggesting the possibility of order~tisorder effects caused by stereochemically favored packing in the liquid phase and energetically favored segment interaction in the liquid mixtures. An attempt to apply the van der Waals model to these data could not predict the experimental binary diffusion coefficients of these systems within the experimental accuracy

Error patterns in Portuguese students' addition and subtraction calculation tasks: Implications for teaching

Purpose The purpose of this descriptive study is to investigate why some elementary children have difficulties mastering addition and subtraction calculation tasks. Design/methodology/approach The researchers have examined error types in addition and subtraction calculation made by 697 Portuguese students in elementary grades. Each student completed a written assessment of mathematical knowledge. A system code (e.g. FR = failure to regroup) has been used to grade the tests. A reliability check has been performed on 65 per cent randomly selected exams. Findings Data frequency analyses reveal that the most common type of error was miscalculation for both addition (n = 164; 38.6 per cent) and subtraction (n = 180; 21.7 per cent). The second most common error type was related to failure to regroup in addition (n = 74; 17.5 per cent) and subtraction (n = 139; 16.3 per cent). Frequency of error types by grade level has been provided. Findings from the hierarchical regression analyses indicate that students’ performance differences emerged as a function of error types which indicated students’ types of difficulties. Research limitations/implications There are several limitations of this study: the use of a convenient sample; all schools were located in the northern region of Portugal; the limited number of problems; and the time of the year of assessment. Practical implications Students’ errors suggested that their performance in calculation tasks is related to conceptual and procedural knowledge and skills. Error analysis allows teachers to better understand the individual performance of a diverse group and to tailor instruction to ensure that all students have an opportunity to succeed in mathematics. Social implications Error analysis helps teachers uncover individual students’ difficulties and deliver meaningful instruction to all students. Originality/value This paper adds to the international literature on error analysis and reinforces its value in diagnosing students’ type and severity of math difficultiesinfo:eu-repo/semantics/publishedVersio

Eugenia membranifolia: a long-forgotten Brazilian Atlantic rainforest Myrtaceae

Eugenia membranifolia Niedenzu, a forgotten name in Brazilian Myrtaceae and presently known only from one isotype, is reported as the correct name for most of the gatherings until now identified as Eugenia bocainensis. We provide a detailed description of E. membranifolia with comments on its distribution, ecology and conservation status, and compare it with E. bocainensis. Key words: Eugenia bocainensis, IUCN Red List, Myrteae, Phyllocaly

Robin boundary conditions in acoustic BTZ black holes

We introduce an analog model for the conformally coupled scalar field on the BTZ black hole. The model is based on the propagation of acoustic waves in a Laval nozzle. Since the BTZ black hole is not a globally hyperbolic spacetime, the dynamics of the scalar field is not well defined until extra boundary conditions are prescribed at its spatial infinity. We show that quasinormal modes (QNMs) satisfying Dirichlet, Neumann, and Robin boundary conditions in the BTZ black hole can be interpreted in terms of ordinary QNMs defined with respect to an appropriately extended nozzle. We also discuss the stability of our model with respect to small perturbations.Comment: 12 pages, 6 figure

Casting the light of the theory of opposition onto Hohfeld's fundamental legal concepts

At the core of Hohfeld's contribution to legal theory is a conceptual framework for the analysis of the legal positions occupied by agents in intersubjective legal relations. Hohfeld presented a system of eight fundamental concepts relying on notions of opposition and correlation. Throughout the years, a number of authors have followed Hohfeld in applying the notion of opposition to analyze legal concepts. Many of these authors have accounted for Hohfeld's theory in direct analogy with the standard deontic hexagon. This paper reviews some of these accounts and extends them employing recent developments from opposition theory. In particular, we are able to extend application of opposition theory to an open conception of the law. We also account for the implications of abandoning the assumption of conflict-freedom and admitting seemingly conflicting legal positions. This enables a fuller analysis of Hohfeld's conceptual analytical framework. We also offer a novel analysis of Hohfeld's power positions.</p

Malária: uma abordagem dinâmica sobre a doença

Introduction: Malaria is a secular disease, a disease with the greatest impact in the world. It is endemic in several states of the Brazilian Amazon. Its etiological agent is protozoan of the genus Plasmodium, its transmission being caused by mosquito bites of the genus Anopheles. Methods: It was used the main bases of scientific information texts about the disease in its most varied aspects such as: epidemiology, disease biology, parasite and vector; Clinical aspects and other important points that could give conditions of broad understanding regarding this blood parasitosis. &nbsp;Development: Malaria can be called malaria, palmar fever, malaria, malaria, seizão terçã fever (benign or malignant) quartã fever, shaking, or an electric kettle depending on the region. It is an endemic disease of the States that make up the Brazilian Amazon. It has a wide world distribution and several clinical-epidemiological knowledge involved in its biological cycle. Conclusion: However, it was possible to conclude that, despite a few studies on malaria in all its aspects, it has a significant impact on the development of goals for its control and the development of diverse studies on malaria.Introdução: A malária é uma doença secular, considerada como a doença de maior impacto no mundo, é endêmica em diversos Estados da Amazônia brasileira, seu agente etiológico são protozoários do gênero Plasmodium, sendo sua transmissão feita pela picada de mosquitos do gênero Anopheles. Métodos: Foram utilizadas as principais bases de informações científicas textos sobre a doença em seus mais variados aspectos como, epidemiologia, biologia da doença, parasita e do vetor; aspectos clínicos e outros pontos importantes que pudessem dar condições de entendimento amplo a respeito dessa parasitose sanguínea. Desenvolvimento: A malária pode ser chamada de paludismo, febre palustre, impaludismo, maleita, sezão febre terçã (benigna ou maligna) febre quartã, tremedeira, batedeira, dependendo da região. É uma doença endêmica dos Estados que compõem a Amazônia brasileira. Possui ampla distribuição mundial e diversos aspectos clínico-epidemiológicos envolvidos em seu ciclo biológico. Conclusão: Contudo foi possível concluir que, apesar de poucos, os estudos sobre a malária em seus diversos aspectos, tem impacto significativo na elaboração de metas para o seu controle e no desenvolvimento de estudos diversos sobre a doença

A ELEIÇÃO DA NOVA MESA DIRETORA DO TRIBUNAL DE JUSTIÇA DO ESTADO DA BAHIA

Na última quarta-feira, em sessão Plenária, histórica, célere, democrática, graças ao sistema eletrônico de votação, e a firme condução do Desembargador LOURIVAL ALMEIDA TRINDADE, cuja gestão ficará indelevelmente marcada na história pela transparência administrativa, por suas atitudes sempre democráticas, o Tribunal de Justiça elegeu a nova Mesa Diretora da nossa mais longeva Corte de Justiça das Américas, instalada em 1609, nesta velha São Salvador da Bahia, capital do Brasil, então colônia de Portugal, com a denominação de Tribunal da Relação com jurisdição em todo território brasileiro colonial e mais a colônia de Angola, Áfric

NOBEL DA PAZ: HOMENAGEM À LIBERDADE DE IMPRENSA!

Ao anunciar a outorga do prêmio Nobel da Paz de 2021, Berit Reiss-Anderson, presidente do Conselho responsável pela escolha da láurea que conferiu o tão esperado prêmio aos Jornalistas MARIA RESSA e DIMITRY MURATOV, respectivamente responsáveis “pela luta corajosa” na defesa vigorosa da liberdade de expressão nas Filipinas e na Rússia, onde os regimes políticos vigentes passam longe da democracia, fez questão de enfatizar: são representantes de todos os jornalistas que defendem este ideal em um mundo em que a democracia e a liberdade de imprensa enfrentam condições cada vez mais adversas