Sign changes of error terms related to arithmetical functions

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Warehouse Storing and Collecting of Parts

This report deals with reducing the high costs resulting from the wear and tear of the fork-lifts used to store or collect items in a warehouse. Two problems were identified and addressed separately. One concerns the way items should be stored or collected at storage locations on the shelves of one corridor. The other problem seeks for an efficient way to define which fork-lift should operate on each corridor, and the order by which the fork-lifts should visit the corridors. We give to both problems formulations that fit in the framework of combinatorial optimization

Complete j-MDP convolutional codes

Maximum distance profile (MDP) convolutional codes have been proven to be very suitable for transmission over an erasure channel. In addition, the subclass of complete MDP convolutional codes has the ability to restart decoding after a burst of erasures. However, there is a lack of constructions of these codes over fields of small size. In this paper, we introduce the notion of complete j-MDP convolutional codes, which are a generalization of complete MDP convolutional codes, and describe their decoding properties. In particular, we present a decoding algorithm for decoding erasures within a given time delay T and show that complete T-MDP convolutional codes are optimal for this algorithm. Moreover, using a computer search with the MAPLE software, we determine the minimal binary and non-binary field size for the existence of (2,1,2) complete j-MDP convolutional codes and provide corresponding constructions. We give a description of all (2,1,2) complete MDP convolutional codes over the smallest possible fields, namely F_13 and F_16 and we also give constructions for (2,1,3) complete 4-MDP convolutional codes over F_128 obtained by a randomized computer search.Comment: 2

An extension of the Euclid-Euler theorem to certain α-perfect numbers

In a posthumously published work, Euler proved that all even perfect numbers are of the form 2^(p-1)(2^p−1), where 2^p−1 is a prime number. In this article, we extend Euler’s method for certain α-perfect numbers for which Euler’s result can be generalized. In particular, we use Euler’s method to prove that if N is a 3-perfect number divisible by 6; then either 2 || N or 3 || N. As well, we prove that if N is a 5/2-perfect number divisible by 5, then 2^4 || N, 5^2 || N, and 31^2| N. Finally, for p ∈ {17, 257, 65537}, we prove that there are no 2p/(p−1)-perfect numbers divisible by p.publishe

Evolution of microstructure, texture and grain boundary character distribution of potassium doped tungsten fibers annealed at variable temperatures

The effect of the annealing temperature on the microstructure and grain boundary character distribution of potassium doped tungsten fibers made of drawn wire was investigated by Electron Backscatter Diffraction. Samples, with a diameter of 148.7 μm, in the as-received condition and annealed at 1300, 1600, 1900, 2100 and 2300 °C were analyzed at the center of the transversal sections. Up to 1900 °C, a uniform microstructural coarsening and primary recrystallization followed by normal grain growth was observed. Between 1900 and 2100 °C abnormal grain growth took place. The strong texture (<110> parallel to the drawing axis) remained present in all conditions. With increasing the annealing temperature, the low angle grain boundary fraction increased at the expense of high angle grain boundaries while the amount of coincidence site lattice boundaries reached its maximum at 1600 °C. At this temperature, the most resistant configuration of triple junctions against intergranular crack propagation was obtained

Psychometric properties of the stress questionnaire on diabetes in portuguese adolescents

O Stresse face à diabetes desempenha um papel determinante na adesão ao tratamento, no controlo metabólico e na qualidade de vida do adolescente. O presente trabalho teve como objectivo a adaptação do Questionário de Stresse face à diabetes (QSD-R) numa amostra de 256 adolescentes com Diabetes tipo 1. Os resultados apontam para a existência de qualidades psicométricas que permitem a sua utilização com adolescentes diabéticos. O questionário apresenta uma consistência interna semelhante à versão original (α = 0,93), sendo composto por 40 itens organizados em seis componentes: Queixas somáticas (α =0,81), Stresse social e escolar (α = 0,82), Ansiedade/depressão (α= 0,77), Stresse face à hipoglicemia (α = 79), Relação médicodoente (α = 0,75), Regime terapêutico (α = 0,72). A versão portuguesa do QSD-R eliminou as duas escalas referentes á relação conjugal e stresse no trabalho e foram inseridos itens referentes ao stresse em contexto escolar. A validade externa permite constatar que o QSD-R apresenta uma correlação com a adesão ao tratamento (r= 0,17; p= 0,03) e com a qualidade de vida (r= 0,55; p=0,0001). Não se verificam diferenças entre adolescentes de ambos os sexos nem variação no nível do stresse ao longo da idade.Stress towards diabetes and its treatment is determinant in treatment adherence, metabolic control and quality of life in adolescents. This study aimed to validate the Questionnaire of Stress on Diabetes- Revised (QSD-R), in a sample of 256 adolescents with type 1 diabetes. The results showed psychometric qualities that allow the use of QSD-R with Portuguese adolescents with diabetes. The questionnaire reveals an internal consistency similar to the original version (alpha of .93), consisting of 40 items organized into six components: Somatic complaints (alpha of .81), Stress and in school and social activities (alpha of .82), Anxiety / Depression (alpha of .77), Stress in the face of hypoglycemia (alpha of .79), Doctor-patient relationship (alpha of .75), Treatment regimen (alpha of .72). In the Portuguese version of the QSD-R, the marital relationship and the work stress scales were eliminated and items related to stress in school activities were added. The external validity revealed QSD-R to be correlated with treatment adherence (r = .17, p = .03) and quality of life (r = .55, p = .0001). No differences between teenagers of both sexes were found as well as variation in stress levels, according to age

Questionário de Avaliação da Qualidade de Vida para adolescentes com Diabetes tipo 1 : estudo de validação do DQOL

A Diabetes Tipo 1 é uma doença crónica complexa e de difícil controlo. Esta dificuldade é mais notória na adolescência, período em que a problemática que envolve a transição da dependência parental para uma vida mais autónoma. A adolescência caracteriza-se também por alterações nas características psicossociais que se podem repercutir na adesão ao tratamento, no controlo metabólico da Diabetes e na qualidade de vida. O objectivo da presente investigação é adaptar um questionário de avaliação da qualidade de vida para adolescentes. A amostra que constituiu o presente estudo foi composta por 256 adolescentes, com idades compreendidas entre os dez e os dezoito anos. O diagnóstico foi efectuado pelo menos um ano antes da colheita de dados. A versão portuguesa do DQOL apresenta-se com um número total de itens mais reduzido que a versão original os quais se agrupam em três factores que avaliam o IMPACTO da diabetes na vida actual do adolescente, a SATISFAÇÃO com o tratamento e a vida e a PREOCUPAÇÃO quanto ao futuro. Revela uma consistência interna excelente. A intercorrelação entre as sub-escalas que a compõem é também boa. Duas das subescalas revelam um poder discriminante heterogéneo quanto ao género e nas diversas faixas etárias da adolescência. Por fim apresenta uma elevada validade convergente, correlacionando-se de forma significativa com um questionário de ansiedade face à Diabetes.Diabetes Type 1 is a complex chronic disease that is difficult to control especially during adolescence. This is due in part to the developmental transition of adolescence from dependency on parents to a more autonomous lifestyle. Adolescence is also marked by a change in psychosocial characteristics that have an impact on adherence to treatment, metabolic control and quality of life in diabetics. The purpose of this study is to adapt a questionnaire of quality of life for adolescents with diabetes Type 1. The research included 256 adolescents, aged 10 to 18 years from the Pediatric Department of Hospital S. João – Porto. Diabetes was diagnosed at least a year prior to data collection. The Portuguese version of DQOL has a smaller number of items than the original version gathered in 3 factors that assess IMPACT of Diabetes in the adolescent day to day life (13 items), SATISFACTION with treatment and life (17 items) and WORRY towards the future (6 items). The scale shows an excellent internal consistency. The intercorrelation between the subscales is also good. The scale is able to discriminate between gender and age according to three phases of adolescence in two of the subscales. It also shows an excellent convergent validity being highly correlated with a questionnaire of anxiety towards diabetes

From 1D convolutional codes to 2D convolutional codes of rate 1/n

In this paper we introduce a new type of superregular matrices that give rise to novel constructions of two-dimensional (2D) convolutional codes with finite support. These codes are of rate 1=n and degree d with n d +1 and achieve the maximum possible distance among all 2D convolutional codes with finite support with the same parameters

An exploratory design science research on troll factories

Private and military troll factories (facilities used to spread rumours in online social media) are currently proliferating around the world. By their very nature, they are obscure companies whose internal workings are largely unknown, apart from leaks to the press. They are even more concealed when it comes to their underlying technology. At least in a broad sense, it is believed that there are two main tasks performed by a troll factory: sowing and spreading. The first is to create and, more importantly, maintain a social network that can be used for the spreading task. It is then a wicked long-term activity, subject to all sorts of problems. As an attempt to make this perspective a little clearer, this paper uses exploratory design science research to produce artefacts that could be applied to online rumour spreading in social media. Then, as a hypothesis: it is possible to design a fully automated social media agent capable of sowing a social network on microblogging platforms. The expectation is that it will be possible to identify common opportunities and difficulties in the development of such tools, which in turn will allow an evaluation of the technology, but above all the level of automation of these facilities. The research is based on a general domain Twitter corpus with 4M+ tokens and on ChatGPT, and discusses both knowledge-based and deep learning approaches for smooth tweet generation. These explorations suggest that for the current, widespread and publicly available NLP technology, troll factories work like a call centre; i.e. humans assisted by more or less sophisticated computing tools (often called cyborgs).FCT - Fundação para a Ciência e a Tecnologia(2022.06822