Improved Distributed Algorithms for Exact Shortest Paths

Computing shortest paths is one of the central problems in the theory of distributed computing. For the last few years, substantial progress has been made on the approximate single source shortest paths problem, culminating in an algorithm of Becker et al. [DISC'17] which deterministically computes $(1+o(1))$-approximate shortest paths in $\tilde O(D+\sqrt n)$ time, where $D$ is the hop-diameter of the graph. Up to logarithmic factors, this time complexity is optimal, matching the lower bound of Elkin [STOC'04]. The question of exact shortest paths however saw no algorithmic progress for decades, until the recent breakthrough of Elkin [STOC'17], which established a sublinear-time algorithm for exact single source shortest paths on undirected graphs. Shortly after, Huang et al. [FOCS'17] provided improved algorithms for exact all pairs shortest paths problem on directed graphs. In this paper, we present a new single-source shortest path algorithm with complexity $\tilde O(n^{3/4}D^{1/4})$. For polylogarithmic $D$, this improves on Elkin's $\tilde{O}(n^{5/6})$ bound and gets closer to the $\tilde{\Omega}(n^{1/2})$ lower bound of Elkin [STOC'04]. For larger values of $D$, we present an improved variant of our algorithm which achieves complexity $\tilde{O}\left( n^{3/4+o(1)}+ \min\{ n^{3/4}D^{1/6},n^{6/7}\}+D\right)$, and thus compares favorably with Elkin's bound of $\tilde{O}(n^{5/6} + n^{2/3}D^{1/3} + D )$ in essentially the entire range of parameters. This algorithm provides also a qualitative improvement, because it works for the more challenging case of directed graphs (i.e., graphs where the two directions of an edge can have different weights), constituting the first sublinear-time algorithm for directed graphs. Our algorithm also extends to the case of exact $\kappa$-source shortest paths...Comment: 26 page

Migration and the Rural-Urban Continuum: Evidence from Bukidnon, Philippines

This paper explores the heterogeneity of the migrant experience using the Bukidnon Panel Survey, which follows up 448 families in rural Mindanao who were first interviewed in 1984-85, as well as their offspring. Migration patterns are examined using the full listing of children of the original respondents as well as a special survey including 257 of the migrant offspring who were tracked down and interviewed in 2004. The migrant survey focuses on differences in the migration experience of males and females who migrated to rural, poblacion, and urban areas. The study finds that rural areas, poblaciones, and urban areas systematically attract different types of migrants. It also finds that the most important determinants of an individual`s location decision are life-cycle effects, specifically marriage and educational attainment.migration, Bukidnon, migration decision, migration pattern

The Role of PIDS and Its Contribution to Research and Policymaking in the Philippines

Established in 1977, the Philippine Institute for Development Studies (PIDS) has been an important research resource in the country. It has served to bring together an unprecedented concentration of intellectual minds from institutions and organizations all over the country and abroad--to engage in an independent agenda that has generated a prolific body of work with a strong orientation and focus on policy. But how effective has this been? The author gives a brisk overview of why the wealth of insights and recommendations have not translated into enhanced developmental outcomes and laments that Philippine governments since at least Macapagal and Marcos have never built on each other--they "just selectively chose what they liked, not what the country needed."policy research, Philippine development

A relational view of Psychological Empowerment and Sense of Community in academic contexts: a preliminary study

Scholars need to pay attention to understand the factors that shape the interactions between individuals and social groups. Constructs like Psychological Sense of Community (PSoC) and Psychological Empowerment (PE) are powerful constructs used to evaluate the antecedents and the consequences of individual attachment to social settings. In parallel, recent advances in network analysis show that the position occupied within whole networks and ego-centric networks are relational factors that affect the subjective perception of membership to social groups. Studies that are conducted in organizational and community settings show strong associations between PSoC and PE. However, these connections have rarely been evaluated within natural settings such as the classroom context. On the other hand, although the theoretic basis of PSoC and PE claims that both processes are formed in a relational way, there are few studies that empirically evaluate the effects of social connectedness on the emergence of PSoC—referred to the classroom—and PE referred to academic-task development. The aim of this research is to determine the effects that the position occupied in formal and informal exchange networks induce on PSoC and PE dimensions. Sixty-four students enrolled in a master degree program (women = 68.8%, Mean age = 26.09, SD = 3.88) participated in this cross-sectional study. Multivariate analyses and network analyses were performed to test the hypotheses under study. The main research finding is that PSoC and PE are synergistic constructs that mutually shape to each other. In relational terms, by sending several nominations in informal networks, it is possible to generate notable impacts on some PSoC dimensions, while receipt of a wide number of nominations in formal contact networks is associated with high levels of PE. In addition, individuals who present high levels of PE are located in the core of formal exchange networks. These results are discussed in order to design actions to increase PSoC and PE in postgraduate academic settings

Migration and the Rural-Urban Continuum: Evidence from Bukidnon, Philippines

This paper explores the heterogeneity of the migrant experience using the Bukidnon Panel Survey, which follows up 448 families in rural Mindanao who were first interviewed in 1984-85, as well as their offspring. Migration patterns are examined using the full listing of children of the original respondents as well as a special survey including 257 of the migrant offspring who were tracked down and interviewed in 2004. The migrant survey focuses on differences in the migration experience of males and females who migrated to rural, poblacion, and urban areas. The study finds that rural areas, poblaciones, and urban areas systematically attract different types of migrants. It also finds that the most important determinants of an individual`s location decision are life-cycle effects, specifically marriage and educational attainment.migration, Bukidnon, migration decision, migration pattern

The Role of PIDS and Its Contribution to Research and Policymaking in the Philippines

Established in 1977, the Philippine Institute for Development Studies (PIDS) has been an important research resource in the country. It has served to bring together an unprecedented concentration of intellectual minds from institutions and organizations all over the country and abroad--to engage in an independent agenda that has generated a prolific body of work with a strong orientation and focus on policy. But how effective has this been? The author gives a brisk overview of why the wealth of insights and recommendations have not translated into enhanced developmental outcomes and laments that Philippine governments since at least Macapagal and Marcos have never built on each other--they "just selectively chose what they liked, not what the country needed."policy research, Philippine development

Automated team selection and compliance checking in business processes

Plenty of activities in many business contexts must be performed collaboratively, e.g., in a hospital or when organising a conference. Tasks such as team composition and allocation are usually performed manually and on the ground of limited criteria such as individual skills, a.o. because adequate automatic support is missing. This paper addresses this shortcoming. We present an approach for team selection and compliance checking in business processes, which includes (i) a language for describing teams; (ii) a way to de- ne team selection conditions and policies related to team composition; and (iii) a mechanism for the automatic resolution of the team selection conditions and for team-related compliance checking based on formal ontologies.Austrian Research Funding Association (FFG) 845638 (SHAPE)Ministerio de Ciencia e Innovación TIN2009-07366 (SETI)Ministerio de Economía y Competitividad TIN2012-32273 (TAPAS)Junta de Andalucía TIC-5906 (THEOS

Nuclear Astrophysics

Nuclear physics has a long and productive history of application to astrophysics which continues today. Advances in the accuracy and breadth of astrophysical data and theory drive the need for better experimental and theoretical understanding of the underlying nuclear physics. This paper will review some of the scenarios where nuclear physics plays an important role, including Big Bang Nucleosynthesis, neutrino production by our sun, nucleosynthesis in novae, the creation of elements heavier than iron, and neutron stars. Big-bang nucleosynthesis is concerned with the formation of elements with A <= 7 in the early Universe; the primary nuclear physics inputs required are few-nucleon reaction cross sections. The nucleosynthesis of heavier elements involves a variety of proton-, alpha-, neutron-, and photon-induced reactions, coupled with radioactive decay. The advent of radioactive ion beam facilities has opened an important new avenue for studying these processes, as many involve radioactive species. Nuclear physics also plays an important role in neutron stars: both the nuclear equation of state and cooling processes involving neutrino emission play a very important role. Recent developments and also the interplay between nuclear physics and astrophysics will be highlighted.Comment: To be published in the Proceedings of 19th Lake Louise Winter Institute (15-21 February 2004). 9 pages, 3 figure