Distributed Approximation Algorithms for Weighted Shortest Paths

A distributed network is modeled by a graph having $n$ nodes (processors) and diameter $D$. We study the time complexity of approximating {\em weighted} (undirected) shortest paths on distributed networks with a $O(\log n)$ {\em bandwidth restriction} on edges (the standard synchronous \congest model). The question whether approximation algorithms help speed up the shortest paths (more precisely distance computation) was raised since at least 2004 by Elkin (SIGACT News 2004). The unweighted case of this problem is well-understood while its weighted counterpart is fundamental problem in the area of distributed approximation algorithms and remains widely open. We present new algorithms for computing both single-source shortest paths (\sssp) and all-pairs shortest paths (\apsp) in the weighted case. Our main result is an algorithm for \sssp. Previous results are the classic $O(n)$-time Bellman-Ford algorithm and an $\tilde O(n^{1/2+1/2k}+D)$-time $(8k\lceil \log (k+1) \rceil -1)$-approximation algorithm, for any integer $k\geq 1$, which follows from the result of Lenzen and Patt-Shamir (STOC 2013). (Note that Lenzen and Patt-Shamir in fact solve a harder problem, and we use $\tilde O(\cdot)$ to hide the O(\poly\log n) term.) We present an $\tilde O(n^{1/2}D^{1/4}+D)$-time $(1+o(1))$-approximation algorithm for \sssp. This algorithm is {\em sublinear-time} as long as $D$ is sublinear, thus yielding a sublinear-time algorithm with almost optimal solution. When $D$ is small, our running time matches the lower bound of $\tilde \Omega(n^{1/2}+D)$ by Das Sarma et al. (SICOMP 2012), which holds even when $D=\Theta(\log n)$, up to a \poly\log n factor.Comment: Full version of STOC 201

Uji Aktivitas Antioksidan Ekstrak Daun dan Kulit Labu Air (Lagenaria Siceraria (Molina) Standl.)

The aim of the study was to determine the inhibitory concentration (IC50) of free radicals on an extract of calabash\u27s leaves and skins. The sample used in this study was the extract of calabash\u27s leaves and skins that made of 100 mg/L concentration. Determination inhibitory concentration of free radicals after adding DPPH (2,2-diphenyl-1-picrylhydrazyl) on the samples was determined using UV-Vis spectrophotometry. Concentration variations in leaves and skins extract of calabash used was 5, 10, 15 and 20 mg/L. The positive control used a vitamin C solution with a concentration that identical to the concentration of sample 5, 10, 15 and 20 mg/L. In the other hand, the negative control used a DPPH solution that was dissolved in ethanol p.a. The results showed that the leaves and skins extract of calabash with control of vitamin C have a concentration inhibition of free radicals (IC50) respectively was 9.268 mg/L (leaf extract), 9.332 mg/L (skin extract) and 6.839 mg/L (Vitamin C). The matter it was indicated that leaves and skins extract of calabash was a powerfully natural antioxidant

Pengaruh Alat Permainan Edukatif terhadap Aspek Perkembangan pada Anak PRA Sekolah di Wilayah Puskesmas Ondong Kabupaten Kepulauan Siau Tagulandang Biaro

Educated gane tool is a kind of gane which consists of educational value it is functioned to stimuli children\u27s imagination cognitively. The process is to give stimulus so it can increase the development skill and socializing a independency. The purpose of this research is to know the effect of educated game tool to preschool children development. The method of this research is one pre-post test group which the researcher observed before and after treatment. The sample is purposive sampling, total of the sampling is 17 respondent. Data which was gotten then analyzed by using wilcoxon signed ranks. The result of the research shows (p=0,000 < α=0,05), it means that there is effect from educated game tool to pre school childreen. From these result, it is suggested to parents a school to pay more attention to pre school children\u27s development especially speaking, language, socializing a independence ability

Sistem Pelayanan Kesehatan Puskesmas Akelamo di Kecamatan Sahu Timur Kabupaten Halmahera Barat

Health care system is a very important in dunya health through this system in expecting health qualityespecially in Indonesia through this system health development goals can be achieved by effective and fixedtarget. Succse health care system depends on the various components that enter in health services Includingnurses, doctors, or other supportive health teams. Satisfy people's expectations and needs. One effort that isdone is to provide facilities, health services in the intention of course is a fast service, precise, cheap andfriendly. The purpose of this study is to provide input for puskesmas akelamo benefit of this research is toprovide input for puskesmas or stakeholder in sub-district east of west halmahera regency. The method usedis qualitative method with the type of descriptive approach and the location of research in the sub-district ofeastern district of west halmahera data collection is done is the observation and in-depth interviews ofinformants.Based on the results of the study there are several serious factors to be improved in which facilitiesand infrastructure facilities are inadequate drugs limited and lack of cooperation across sector programsless attention from the government, so that the impact becomes a barrier in service to the community

Alternative approach to electromagnetic field quantization in nonlinear and inhomogeneous media

A simple approach is proposed for the quantization of the electromagnetic field in nonlinear and inhomogeneous media. Given the dielectric function and nonlinear susceptibilities, the Hamiltonian of the electromagnetic field is determined completely by this quantization method. From Heisenberg's equations we derive Maxwell's equations for the field operators. When the nonlinearity goes to zero, this quantization method returns to the generalized canonical quantization procedure for linear inhomogeneous media [Phys. Rev. A, 43, 467, 1991]. The explicit Hamiltonians for the second-order and third-order nonlinear quasi-steady-state processes are obtained based on this quantization procedure.Comment: Corrections in references and introductio

Tropical sea surface temperatures for the past four centuries reconstructed from coral archives

Most annually resolved climate reconstructions of the Common Era are based on terrestrial data, making it a challenge to independently assess how recent climate changes have affected the oceans. Here as part of the Past Global Changes Ocean2K project, we present four regionally calibrated and validated reconstructions of sea surface temperatures in the tropics, based on 57 published and publicly archived marine paleoclimate data sets derived exclusively from tropical coral archives. Validation exercises suggest that our reconstructions are interpretable for much of the past 400 years, depending on the availability of paleoclimate data within, and the reconstruction validation statistics for, each target region. Analysis of the trends in the data suggests that the Indian, western Pacific, and western Atlantic Ocean regions were cooling until modern warming began around the 1830s. The early 1800s were an exceptionally cool period in the Indo-Pacific region, likely due to multiple large tropical volcanic eruptions occurring in the early nineteenth century. Decadal-scale variability is a quasi-persistent feature of all basins. Twentieth century warming associated with greenhouse gas emissions is apparent in the Indian, West Pacific, and western Atlantic Oceans, but we find no evidence that either natural or anthropogenic forcings have altered El Ni ˜no–Southern Oscillation-related variance in tropical sea surface temperatures. Our marine-based regional paleoclimate reconstructions serve as benchmarks against which terrestrial reconstructions as well as climate model simulations can be compared and as a basis for studying the processes by which the tropical oceans mediate climate variability and change