Parallel Construction of Wavelet Trees on Multicore Architectures

The wavelet tree has become a very useful data structure to efficiently represent and query large volumes of data in many different domains, from bioinformatics to geographic information systems. One problem with wavelet trees is their construction time. In this paper, we introduce two algorithms that reduce the time complexity of a wavelet tree's construction by taking advantage of nowadays ubiquitous multicore machines. Our first algorithm constructs all the levels of the wavelet in parallel in $O(n)$ time and $O(n\lg\sigma + \sigma\lg n)$ bits of working space, where $n$ is the size of the input sequence and $\sigma$ is the size of the alphabet. Our second algorithm constructs the wavelet tree in a domain-decomposition fashion, using our first algorithm in each segment, reaching $O(\lg n)$ time and $O(n\lg\sigma + p\sigma\lg n/\lg\sigma)$ bits of extra space, where $p$ is the number of available cores. Both algorithms are practical and report good speedup for large real datasets.Comment: This research has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sk{\l}odowska-Curie Actions H2020-MSCA-RISE-2015 BIRDS GA No. 69094

Article 13 on social media and news media: disintermediation and reintermediation on the modern media landscape

The former Article 13 (now Article 17) of the European directive on copyright and the internet (Directive EC2019/790) has been under negotiations since 2016 and was finally approved in 2019. In Portugal, however, the issue was mostly absent from public scrutiny and debate until November 2018. In that month, the issue arose to a prominent level, both in news media and in social media, following a wave of alerts issued by various young youtubers, incentivized by YouTube management. In this paper, we engage in the discussion concerning disintermediation, studying the way in which such alerts spread both in news media and social media, and understanding the role played by the users of social media platforms in modelling the social relevance and the social discourse of the issue of copyright and the internet. To do so, we used digital methods, collecting and analysing data from Twitter, YouTube and from online news media, mapping Article 13 discussions and identifying key actors in each field, as well as the connections between them. The results show that the ease of access provided by platforms such as Twitter or YouTube converts some users to prominent influencers and that, in some cases, those influencers are able to shift and model the public discourse about relevant collective issues

Energy Consumption in Compact Integer Vectors: A Study Case

[Abstract] In the field of algorithms and data structures analysis and design, most of the researchers focus only on the space/time trade-off, and little attention has been paid to energy consumption. Moreover, most of the efforts in the field of Green Computing have been devoted to hardware-related issues, being green software in its infancy. Optimizing the usage of computing resources, minimizing power consumption or increasing battery life are some of the goals of this field of research. As an attempt to address the most recent sustainability challenges, we must incorporate the energy consumption as a first-class constraint when designing new compact data structures. Thus, as a preliminary work to reach that goal, we first need to understand the factors that impact on the energy consumption and their relation with compression. In this work, we study the energy consumption required by several integer vector representations. We execute typical operations over datasets of different nature. We can see that, as commonly believed, energy consumption is highly related to the time required by the process, but not always. We analyze other parameters, such as number of instructions, number of CPU cycles, memory loads, among others.Ministerio de Ciencia, Innovación y Universidades; TIN2016-77158-C4-3-RMinisterio de Ciencia, Innovación y Universidades; RTC-2017-5908-7Xunta de Galicia (co-founded with ERDF); ED431C 2017/58Xunta de Galicia; ED431G/01Comisión Nacional de Investigación Científica y Tecnológica; 3170534

Relationship between dietary energy intake, nutritional status and cardiovascular risk in adults from the communes of Quellón and Chonchi, Chiloé, Chile

Introduction: Behavioural and metabolic risk factors are responsible for the greatest burden of disease; an unhealthy diet, along with abdominal obesity, are risk factors related to Non-communicable diseases (NCDs). Methods: Data concerning food patterns were determined by the application of an interview-type instrument, used to assess the daily and weekly frequency of consumption; cardiovascular risk was assessed using waist circumference, and nutritional status via Body Mass Index. Student's t test was applied to evaluate the differences between variables and the Pearson's chi-square test for the association of variables. Results: Dietary energy intake (kcal/capita/day) was 3000 kcal, with an average distribution of 12.2% (proteins), 46.9% (carbohydrates), and 40.9% (total fats). The 78% of the sample suffered from malnutrition by excess. About 37.5% had Non-Communicable Diseases, with high blood pressure being the most frequent disease among both genders, with the highest prevalence among women, along with diabetes mellitus and dyslipidaemia. Depending on the nutritional status, the presence of obesity is associated with high cardiovascular risk (p=0.000), greater energy availability (p=0.012), and an increased occurrence of non-communicable diseases (p=0.004). Conclusions: Malnutrition by excess figures support the global alert for obesity and overweight, which are considered to be a pandemic; in addition, Chiloé is not immune to the increasing trend of processed and ultra-processed food consumption

Bounded and unbounded polynomials and multilinear forms: Characterizing continuity

In this paper we prove a characterization of continuity for polynomials on a normed space. Namely, we prove that a polynomial is continuous if and only if it maps compact sets into compact sets. We also provide a partial answer to the question as to whether a polynomial is continuous if and only if it transforms connected sets into connected sets. These results motivate the natural question as to how many non-continuous polynomials there are on an infinite dimensional normed space. A problem on the \emph{lineability} of the sets of non-continuous polynomials and multilinear mappings on infinite dimensional normed spaces is answered.Comment: 8 page

Synthetic and theoretical studies of novel ring closure and ring opening reactions

Ring closure and ring opening reactions are in many cases useful synthetic procedures in organic chemistry. They allow the preparation of complex molecules with high stereoselectivity and good yields. Mechanistic and theoretical studies have been carried out on the transformation of 2-aminopyrimidines into imidazo[1,2-c]pyrimidines and guanidines, respectively, through ring closure and ring opening reactions, as well as the transamidation reactions through the ring closure and ring opening of guanidine derivatives, which constitute novel synthetic methods.Sepulveda Arques, Jose, [email protected]

Expectativas y Proyectos de Futuro de Jóvenes Estudiantes Secundarios : Un estudio sobre aspiraciones y segmentación social del sistema educativo chileno

Fil: Sepúlveda V., Leandro. Universidad Alberto Hurtado.Fil: Valdebenito I., María José. Universidad Alberto Hurtado