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

Technical note: An improved methodology for calculating the Southern Annular Mode index to aid consistency between climate studies

The Southern Annular Mode (SAM) strongly influences climate variability in the Southern Hemisphere. The SAM index describes the phase and magnitude of the SAM and can be calculated by measuring the difference in mean sea level pressure (MSLP) between middle and high latitudes. This study investigates the effects of calculation methods and data resolution on the SAM index, and subsequent interpretations of SAM impacts and trends. We show that the normalisation step that is traditionally used in calculating the SAM index leads to substantial differences in the magnitude of the SAM index calculated at different temporal resolutions. Additionally, the equal weighting that the normalisation approach gives to MSLP variability at the middle and high southern latitudes artificially alters temperature and precipitation correlations and the interpretation of climate change trends in the SAM. These issues can be overcome by instead using a natural SAM index based on MSLP anomalies, resulting in consistent scaling and variability in the SAM index calculated at daily, monthly and annual data resolutions. The natural SAM index has improved representation of SAM impacts in the high southern latitudes, including the asymmetric (zonal wave-3) component of MSLP variability, whereas the increased weighting given to mid-latitude MSLP variability in the normalised SAM index incorporates a stronger component of tropical climate variability that is not directly associated with SAM variability. We conclude that an improved approach of calculating the SAM index from MSLP anomalies without normalisation would aid consistency across climate studies and avoid potential ambiguity in the SAM index, including SAM index reconstructions from palaeoclimate data, and thus enable more consistent interpretations of SAM trends and impacts.</p

Hubungan Pengetahuan Pasien Tentang Terapi Infus (Intravena) Dengan Kejadian Flebitis Di Irina a Bawah Rsup Prof. Dr. R. D. Kandou Manado

:Intravenous therapy used for treat various patient conditions. Phlebitis is one of many complication of intravenous therapy distribution. Purpose this study is to know relation knowledge of the patient about infusion teraphy (intravenous) with phlebitis incidence at IRINA A Bawah RSUP Prof. Dr. R. D. Kandou Manado. This study implemented with cross sectional method, sampling poll with total sampling. Obtained total sample is 30 peoples. Data analysis was perfomed using chi-square at the 95% significance level (α 0,05). The result of this study obtained respondents with highest result are patient with male sex (80%), age 31-40 (43,3%), education highschool (53,3%), and most of the respondents have a good knowledge about infusion therapy (76,7%) and not exposed phlebitis (80%). Result of statistic test is no relation between patient knowledge about infusion therapy with phlebitis insidence with P value=0,120> α=0,05. For nursing profesion particulary hospital nurse need to do health education to patient about infusion therapy with the complication. For the patient being on treatment infusion therapy must attention that the medical personil information to prevent the complication of the infusion therapy

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

Dealing with climate change through understanding tropical ocean-atmosphere climate interactions and their impacts on marine ecosystems.

Australian scientists are world leaders in developing robust palaeo-environmental reconstructions from coral archives, relevant for understanding Australian climate extremes. The key issues for advancing this field are the need for high-resolution marine paleoclimate records to place the present in the context of past natural climate and sea level change, and to understand the impact of those changes on marine ecosystems. We call for sustained investment in paleoclimate science, infrastructure, and personnel to advance these critical areas of research

General Variability Leads to Specific Adaptation Toward Energy Optimal Policies

Our nervous systems can learn optimal control policies in response to changes to our bodies, tasks, and movement contexts. For example, humans can learn to adapt their control policy in walking contexts where the energy-optimal policy is shifted along variables such as step frequency or step width. However, it is unclear how the nervous system determines which ways to adapt its control policy. Here, we asked how human participants explore through variations in their control policy to identify more optimal policies in new contexts. We created new contexts using exoskeletons that apply assistive torques to each ankle at each walking step. We analyzed four variables that spanned the levels of the whole movement, the joint, and the muscle: step frequency, ankle angle range, total soleus activity, and total medial gastrocnemius activity. We found that, across all of these analyzed variables, variability increased upon initial exposure to new contexts and then decreased with experience. This led to adaptive changes in the magnitude of specific variables, and these changes were correlated with reduced energetic cost. The timescales by which adaptive changes progressed and variability decreased were faster for some variables than others, suggesting a reduced search space within which the nervous system continues to optimize its policy. These collective findings support the principle that exploration through general variability leads to specific adaptation toward optimal movement policies

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

Patterns and localized structures in bistable semiconductor resonators

We report experiments on spatial switching dynamics and steady state structures of passive nonlinear semiconductor resonators of large Fresnel number. Extended patterns and switching front dynamics are observed and investigated. Evidence of localization of structures is given.Comment: 5 pages with 9 figure