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Sample records for asymmetric traveling salesman

  1. The on-line asymmetric traveling salesman problem

    NARCIS (Netherlands)

    Ausiello, G.; Bonifaci, V.; Laura, L.

    2008-01-01

    We consider two on-line versions of the asymmetric traveling salesman problem with triangle inequality. For the homing version, in which the salesman is required to return in the city where it started from, we give a -competitive algorithm and prove that this is best possible. For the nomadic

  2. A Data-Guided Lexisearch Algorithm for the Asymmetric Traveling Salesman Problem

    Directory of Open Access Journals (Sweden)

    Zakir Hussain Ahmed

    2011-01-01

    Full Text Available A simple lexisearch algorithm that uses path representation method for the asymmetric traveling salesman problem (ATSP is proposed, along with an illustrative example, to obtain exact optimal solution to the problem. Then a data-guided lexisearch algorithm is presented. First, the cost matrix of the problem is transposed depending on the variance of rows and columns, and then the simple lexisearch algorithm is applied. It is shown that this minor preprocessing of the data before the simple lexisearch algorithm is applied improves the computational time substantially. The efficiency of our algorithms to the problem against two existing algorithms has been examined for some TSPLIB and random instances of various sizes. The results show remarkably better performance of our algorithms, especially our data-guided algorithm.

  3. A Hybrid Symbiotic Organisms Search Algorithm with Variable Neighbourhood Search for Solving Symmetric and Asymmetric Traveling Salesman Problem

    Science.gov (United States)

    Umam, M. I. H.; Santosa, B.

    2018-04-01

    Combinatorial optimization has been frequently used to solve both problems in science, engineering, and commercial applications. One combinatorial problems in the field of transportation is to find a shortest travel route that can be taken from the initial point of departure to point of destination, as well as minimizing travel costs and travel time. When the distance from one (initial) node to another (destination) node is the same with the distance to travel back from destination to initial, this problems known to the Traveling Salesman Problem (TSP), otherwise it call as an Asymmetric Traveling Salesman Problem (ATSP). The most recent optimization techniques is Symbiotic Organisms Search (SOS). This paper discuss how to hybrid the SOS algorithm with variable neighborhoods search (SOS-VNS) that can be applied to solve the ATSP problem. The proposed mechanism to add the variable neighborhoods search as a local search is to generate the better initial solution and then we modify the phase of parasites with adapting mechanism of mutation. After modification, the performance of the algorithm SOS-VNS is evaluated with several data sets and then the results is compared with the best known solution and some algorithm such PSO algorithm and SOS original algorithm. The SOS-VNS algorithm shows better results based on convergence, divergence and computing time.

  4. Spatial Transformation of Equality – Generalized Travelling Salesman Problem to Travelling Salesman Problem

    Directory of Open Access Journals (Sweden)

    Mohammed Zia

    2018-03-01

    Full Text Available The Equality-Generalized Travelling Salesman Problem (E-GTSP, which is an extension of the Travelling Salesman Problem (TSP, is stated as follows: given groups of points within a city, like banks, supermarkets, etc., find a minimum cost Hamiltonian cycle that visits each group exactly once. It can model many real-life combinatorial optimization scenarios more efficiently than TSP. This study presents five spatially driven search-algorithms for possible transformation of E-GTSP to TSP by considering the spatial spread of points in a given urban city. Presented algorithms are tested over 15 different cities, classified by their street-network’s fractal-dimension. Obtained results denote that the R-Search algorithm, which selects the points from each group based on their radial separation with respect to the start–end point, is the best search criterion for any E-GTSP to TSP conversion modelled for a city street network. An 8.8% length error has been reported for this algorithm.

  5. FACES WITH LARGE DIAMETER ON THE SYMMETRICAL TRAVELING SALESMAN POLYTOPE

    NARCIS (Netherlands)

    SIERKSMA, G; TIJSSEN, GA

    This paper deals with the symmetric traveling salesman polytope and contains three main theorems. The first one gives a new characterization of (non)adjacency. Based on this characterization a new upper bound for the diameter of the symmetric traveling salesman polytope (conjectured to be 2 by M.

  6. On Labeled Traveling Salesman Problems

    DEFF Research Database (Denmark)

    Couetoux, Basile; Gourves, Laurent; Monnot, Jerome

    2008-01-01

    We consider labeled Traveling Salesman Problems, defined upon a complete graph of n vertices with colored edges. The objective is to find a tour of maximum (or minimum) number of colors. We derive results regarding hardness of approximation, and analyze approximation algorithms for both versions ...

  7. Traveling Salesman Problem with Transportation

    Directory of Open Access Journals (Sweden)

    Valeriu Ungureanu

    2006-09-01

    Full Text Available Traveling Salesman Problem (TSP is a generic name that includes diverse practical models. Motivated by applications, a new model of TSP is examined – a synthesis of classical TSP and classical Transportation Problem. Algorithms based on Integer Programming cutting-plane methods and Branch and Bound Techniques are obvious.

  8. A comparison of lower bounds for the symmetric circulant traveling salesman problem

    NARCIS (Netherlands)

    de Klerk, E.; Dobre, C.

    2011-01-01

    When the matrix of distances between cities is symmetric and circulant, the traveling salesman problem (TSP) reduces to the so-called symmetric circulant traveling salesman problem (SCTSP), that has applications in the design of reconfigurable networks, and in minimizing wallpaper waste. The

  9. QUANTUM INSPIRED PARTICLE SWARM COMBINED WITH LIN-KERNIGHAN-HELSGAUN METHOD TO THE TRAVELING SALESMAN PROBLEM

    Directory of Open Access Journals (Sweden)

    Bruno Avila Leal de Meirelles Herrera

    2015-12-01

    Full Text Available ABSTRACT The Traveling Salesman Problem (TSP is one of the most well-known and studied problems of Operations Research field, more specifically, in the Combinatorial Optimization field. As the TSP is a NP (Non-Deterministic Polynomial time-hard problem, there are several heuristic methods which have been proposed for the past decades in the attempt to solve it the best possible way. The aim of this work is to introduce and to evaluate the performance of some approaches for achieving optimal solution considering some symmetrical and asymmetrical TSP instances, which were taken from the Traveling Salesman Problem Library (TSPLIB. The analyzed approaches were divided into three methods: (i Lin-Kernighan-Helsgaun (LKH algorithm; (ii LKH with initial tour based on uniform distribution; and (iii an hybrid proposal combining Particle Swarm Optimization (PSO with quantum inspired behavior and LKH for local search procedure. The tested algorithms presented promising results in terms of computational cost and solution quality.

  10. On the Core of Multiple Longest Traveling Salesman Games

    NARCIS (Netherlands)

    Estevez Fernandez, M.A.; Borm, P.E.M.; Hamers, H.J.M.

    2003-01-01

    In this paper we introduce multiple longest traveling salesman (MLTS) games. An MLTS game arises from a network in which a salesman has to visit each node (player) precisely once, except its home location, in an order that maximizes the total reward.First it is shown that the value of a coalition of

  11. Boltzmann machines for travelling salesman problems

    NARCIS (Netherlands)

    Aarts, E.H.L.; Korst, J.H.M.

    1989-01-01

    Boltzmann machines are proposed as a massively parallel alternative to the (sequential) simulated annealing algorithm. Our approach is tailored to the travelling salesman problem, but it can also be applied to a more general class of combinatorial optimization problems. For two distinct 0–1

  12. The Quadratic Selective Travelling Salesman Problem

    DEFF Research Database (Denmark)

    Thomadsen, Tommy; Stidsen, Thomas K.

    2003-01-01

    A well-known extension of the Travelling Salesman Problem (TSP) is the Selective TSP (STSP): Each node has an associated profit and instead of visiting all nodes, the most profitable set of nodes, taking into account the tour cost, is visited. The Quadratic STSP (QSTSP) adds the additional...

  13. A NEW HEURISTIC ALGORITHM FOR MULTIPLE TRAVELING SALESMAN PROBLEM

    Directory of Open Access Journals (Sweden)

    F. NURIYEVA

    2017-06-01

    Full Text Available The Multiple Traveling Salesman Problem (mTSP is a combinatorial optimization problem in NP-hard class. The mTSP aims to acquire the minimum cost for traveling a given set of cities by assigning each of them to a different salesman in order to create m number of tours. This paper presents a new heuristic algorithm based on the shortest path algorithm to find a solution for the mTSP. The proposed method has been programmed in C language and its performance analysis has been carried out on the library instances. The computational results show the efficiency of this method.

  14. Branch-and-cut-and-price for the traveling salesman problem with time windows

    DEFF Research Database (Denmark)

    Røpke, Stefan; Madsen, Oli B.G.

    In the traveling salesman problem with time windows (TSPTW) one is given a depot and a set of nodes to be visited by a salesman. The salesman starts his trip at the depot and must visit all nodes while respecting time windows at the nodes. The objective of the problem is to minimize the total...... distance traveled by the salesman. The TSPTW is formulated as a set-partitioning problem which is solved by using combined cut and column generation. The pricing sub problem in the column generation procedure is a shortest path problem with time window constraints and 2-cycle elimination. A standard column...

  15. In Pursuit of the Traveling Salesman Mathematics at the Limits of Computation

    CERN Document Server

    Cook, William J

    2011-01-01

    What is the shortest possible route for a traveling salesman seeking to visit each city on a list exactly once and return to his city of origin? It sounds simple enough, yet the traveling salesman problem is one of the most intensely studied puzzles in applied mathematics--and it has defied solution to this day. In this book, William Cook takes readers on a mathematical excursion, picking up the salesman's trail in the 1800s when Irish mathematician W. R. Hamilton first defined the problem, and venturing to the furthest limits of today's state-of-the-art attempts to solve it. Cook examines

  16. Genetic Algorithm for Traveling Salesman Problem with Modified Cycle Crossover Operator

    Directory of Open Access Journals (Sweden)

    Abid Hussain

    2017-01-01

    Full Text Available Genetic algorithms are evolutionary techniques used for optimization purposes according to survival of the fittest idea. These methods do not ensure optimal solutions; however, they give good approximation usually in time. The genetic algorithms are useful for NP-hard problems, especially the traveling salesman problem. The genetic algorithm depends on selection criteria, crossover, and mutation operators. To tackle the traveling salesman problem using genetic algorithms, there are various representations such as binary, path, adjacency, ordinal, and matrix representations. In this article, we propose a new crossover operator for traveling salesman problem to minimize the total distance. This approach has been linked with path representation, which is the most natural way to represent a legal tour. Computational results are also reported with some traditional path representation methods like partially mapped and order crossovers along with new cycle crossover operator for some benchmark TSPLIB instances and found improvements.

  17. 20 CFR 404.1008 - Agent-driver or commission-driver, full-time life insurance salesman, home worker, or traveling...

    Science.gov (United States)

    2010-04-01

    ... commission-driver, full-time life insurance salesman, home worker, or traveling or city salesman. (a) General... 20 Employees' Benefits 2 2010-04-01 2010-04-01 false Agent-driver or commission-driver, full-time life insurance salesman, home worker, or traveling or city salesman. 404.1008 Section 404.1008...

  18. Solving Dynamic Traveling Salesman Problem Using Dynamic Gaussian Process Regression

    Directory of Open Access Journals (Sweden)

    Stephen M. Akandwanaho

    2014-01-01

    Full Text Available This paper solves the dynamic traveling salesman problem (DTSP using dynamic Gaussian Process Regression (DGPR method. The problem of varying correlation tour is alleviated by the nonstationary covariance function interleaved with DGPR to generate a predictive distribution for DTSP tour. This approach is conjoined with Nearest Neighbor (NN method and the iterated local search to track dynamic optima. Experimental results were obtained on DTSP instances. The comparisons were performed with Genetic Algorithm and Simulated Annealing. The proposed approach demonstrates superiority in finding good traveling salesman problem (TSP tour and less computational time in nonstationary conditions.

  19. Algorithms for the on-line travelling salesman

    NARCIS (Netherlands)

    Ausiello, G.; Feuerstein, E.; Leonardi, S.; Stougie, L.; Talamo, M.

    1999-01-01

    In this paper the problem of efficiently serving a sequence of requests presented in an on-line fashion located at points of a metric space is considered. We call this problem the On-Line Travelling Salesman Problem (OLTSP). It has a variety of relevant applications in logistics and robotics. We

  20. The Electric Traveling Salesman Problem with Time Windows

    DEFF Research Database (Denmark)

    Roberti, Roberto; Wen, Min

    2016-01-01

    To minimize greenhouse gas emissions, the logistic field has seen an increasing usage of electric vehicles. The resulting distribution planning problems present new computational challenges.We address a problem, called Electric Traveling Salesman Problem with Time Windows. We propose a mixed...

  1. THE DUBINS TRAVELING SALESMAN PROBLEM WITH CONSTRAINED COLLECTING MANEUVERS

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    Petr Váňa

    2016-11-01

    Full Text Available In this paper, we introduce a variant of the Dubins traveling salesman problem (DTSP that is called the Dubins traveling salesman problem with constrained collecting maneuvers (DTSP-CM. In contrast to the ordinary formulation of the DTSP, in the proposed DTSP-CM, the vehicle is requested to visit each target by specified collecting maneuver to accomplish the mission. The proposed problem formulation is motivated by scenarios with unmanned aerial vehicles where particular maneuvers are necessary for accomplishing the mission, such as object dropping or data collection with sensor sensitive to changes in vehicle heading. We consider existing methods for the DTSP and propose its modifications to use these methods to address a variant of the introduced DTSP-CM, where the collecting maneuvers are constrained to straight line segments.

  2. Polyhedral combinatorics of the cardinality constrained quadratic knapsack problem and the quadratic selective travelling salesman problem

    DEFF Research Database (Denmark)

    Mak, Vicky; Thomadsen, Tommy

    2006-01-01

    This paper considers the cardinality constrained quadratic knapsack problem (QKP) and the quadratic selective travelling salesman problem (QSTSP). The QKP is a generalization of the knapsack problem and the QSTSP is a generalization of the travelling salesman problem. Thus, both problems are NP...

  3. The traveling salesman problem a computational study

    CERN Document Server

    Applegate, David L; Chvatal, Vasek; Cook, William J

    2006-01-01

    This book presents the latest findings on one of the most intensely investigated subjects in computational mathematics--the traveling salesman problem. It sounds simple enough: given a set of cities and the cost of travel between each pair of them, the problem challenges you to find the cheapest route by which to visit all the cities and return home to where you began. Though seemingly modest, this exercise has inspired studies by mathematicians, chemists, and physicists. Teachers use it in the classroom. It has practical applications in genetics, telecommunications, and neuroscience.

  4. The traveling salesman problem with few inner points

    NARCIS (Netherlands)

    Deineko, V.G.; Hoffmann, M.; Okamoto, Y.; Woeginger, G.J.; Chwa, K.Y.; Munro, J.I.

    2004-01-01

    We study the traveling salesman problem (TSP) in the 2-dimensional Euclidean plane. The problem is NP-hard in general, but trivial if the points are in convex position. In this paper, we investigate the influence of the number of inner points (i.e., points in the interior of the convex hull) on the

  5. A HYBRID HEURISTIC ALGORITHM FOR THE CLUSTERED TRAVELING SALESMAN PROBLEM

    Directory of Open Access Journals (Sweden)

    Mário Mestria

    2016-04-01

    Full Text Available ABSTRACT This paper proposes a hybrid heuristic algorithm, based on the metaheuristics Greedy Randomized Adaptive Search Procedure, Iterated Local Search and Variable Neighborhood Descent, to solve the Clustered Traveling Salesman Problem (CTSP. Hybrid Heuristic algorithm uses several variable neighborhood structures combining the intensification (using local search operators and diversification (constructive heuristic and perturbation routine. In the CTSP, the vertices are partitioned into clusters and all vertices of each cluster have to be visited contiguously. The CTSP is -hard since it includes the well-known Traveling Salesman Problem (TSP as a special case. Our hybrid heuristic is compared with three heuristics from the literature and an exact method. Computational experiments are reported for different classes of instances. Experimental results show that the proposed hybrid heuristic obtains competitive results within reasonable computational time.

  6. Trajectory Stability in the Traveling Salesman Problem

    Directory of Open Access Journals (Sweden)

    Sergio Sánchez

    2018-01-01

    Full Text Available Two generalizations of the traveling salesman problem in which sites change their position in time are presented. The way the rank of different trajectory lengths changes in time is studied using the rank diversity. We analyze the statistical properties of rank distributions and rank dynamics and give evidence that the shortest and longest trajectories are more predictable and robust to change, that is, more stable.

  7. Fluctuations in the site-disordered traveling salesman problem

    Energy Technology Data Exchange (ETDEWEB)

    Dean, David S [Laboratoire de Physique Theorique, UMR CNRS 5152, IRSAMC, Universite Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 04 (France); Lancaster, David [Harrow School of Computer Science, University of Westminster, Harrow HA1 3TP (United Kingdom)

    2007-11-16

    We extend a previous statistical mechanical treatment of the traveling salesman problem by defining a discrete 'site-disordered' problem in which fluctuations about saddle points can be computed. The results clarify the basis of our original treatment, and illuminate but do not resolve the difficulties of taking the zero-temperature limit to obtain minimal path lengths.

  8. An Extension of the Lin-Kernighan-Helsgaun TSP Solver for Constrained Traveling Salesman and Vehicle Routing Problems

    DEFF Research Database (Denmark)

    Helsgaun, Keld

    This report describes the implementation of an extension of the Lin-Kernighan-Helsgaun TSP solver for solving constrained traveling salesman and vehicle routing problems. The extension, which is called LKH-3, is able to solve a variety of well-known problems, including the sequential ordering...... problem (SOP), the traveling repairman problem (TRP), variants of the multiple travel-ing salesman problem (mTSP), as well as vehicle routing problems (VRPs) with capacity, time windows, pickup-and-delivery and distance constraints. The implementation of LKH-3 builds on the idea of transforming...... the problems into standard symmetric traveling salesman problems and handling constraints by means of penalty functions. Extensive testing on benchmark instances from the literature has shown that LKH-3 is effective. Best known solutions are often obtained, and in some cases, new best solutions are found...

  9. 2D and 3D Traveling Salesman Problem

    Science.gov (United States)

    Haxhimusa, Yll; Carpenter, Edward; Catrambone, Joseph; Foldes, David; Stefanov, Emil; Arns, Laura; Pizlo, Zygmunt

    2011-01-01

    When a two-dimensional (2D) traveling salesman problem (TSP) is presented on a computer screen, human subjects can produce near-optimal tours in linear time. In this study we tested human performance on a real and virtual floor, as well as in a three-dimensional (3D) virtual space. Human performance on the real floor is as good as that on a…

  10. Optimization of Gas Flow Network using the Traveling Salesman ...

    African Journals Online (AJOL)

    The overall goal of this paper is to develop a general formulation for an optimal infrastructure layout design of gas pipeline distribution networks using algorithm developed from the application of two industrial engineering concepts: the traveling salesman problem (TSP) and the nearest neighbor (NN). The focus is on the ...

  11. Development of the PEBLebl Traveling Salesman Problem Computerized Testbed

    Science.gov (United States)

    Mueller, Shane T.; Perelman, Brandon S.; Tan, Yin Yin; Thanasuan, Kejkaew

    2015-01-01

    The traveling salesman problem (TSP) is a combinatorial optimization problem that requires finding the shortest path through a set of points ("cities") that returns to the starting point. Because humans provide heuristic near-optimal solutions to Euclidean versions of the problem, it has sometimes been used to investigate human visual…

  12. A parallel 2-opt algorithm for the traveling salesman problem

    NARCIS (Netherlands)

    Verhoeven, M.G.A.; Aarts, E.H.L.; Swinkels, P.C.J.

    1995-01-01

    We present a scalable parallel local search algorithm based on data parallelism. The concept of distributed neighborhood structures is introduced, and applied to the Traveling Salesman Problem (TSP). Our parallel local search algorithm finds the same quality solutions as the classical 2-opt

  13. Dynamic Programming Approaches for the Traveling Salesman Problem with Drone

    NARCIS (Netherlands)

    P. Bouman (Paul); N.A.H. Agatz (Niels); M.E. Schmidt (Marie)

    2017-01-01

    markdownabstractA promising new delivery model involves the use of a delivery truck that collaborates with a drone to make deliveries. Effectively combining a drone and a truck gives rise to a new planning problem that is known as the Traveling Salesman Problem with Drone (TSP-D). This paper

  14. Dynamic Programming Approaches for the Traveling Salesman Problem with Drone

    NARCIS (Netherlands)

    P. Bouman (Paul); N.A.H. Agatz (Niels); M.E. Schmidt (Marie)

    2017-01-01

    markdownabstractA promising new delivery model involves the use of a delivery truck that collaborates with a drone to make deliveries. Effectively combining a truck and a drone gives rise to a new planning problem that is known as the Traveling Salesman Problem with Drone (TSP-D). This paper

  15. Bi-criteria travelling salesman subtour problem with time threshold

    Science.gov (United States)

    Kumar Thenepalle, Jayanth; Singamsetty, Purusotham

    2018-03-01

    This paper deals with the bi-criteria travelling salesman subtour problem with time threshold (BTSSP-T), which comes from the family of the travelling salesman problem (TSP) and is NP-hard in the strong sense. The problem arises in several application domains, mainly in routing and scheduling contexts. Here, the model focuses on two criteria: total travel distance and gains attained. The BTSSP-T aims to determine a subtour that starts and ends at the same city and visits a subset of cities at a minimum travel distance with maximum gains, such that the time spent on the tour does not exceed the predefined time threshold. A zero-one integer-programming problem is adopted to formulate this model with all practical constraints, and it includes a finite set of feasible solutions (one for each tour). Two algorithms, namely, the Lexi-Search Algorithm (LSA) and the Tabu Search (TS) algorithm have been developed to solve the BTSSP-T problem. The proposed LSA implicitly enumerates the feasible patterns and provides an efficient solution with backtracking, whereas the TS, which is metaheuristic, will give the better approximate solution. A numerical example is demonstrated in order to understand the search mechanism of the LSA. Numerical experiments are carried out in the MATLAB environment, on the different benchmark instances available in the TSPLIB domain as well as on randomly generated test instances. The experimental results show that the proposed LSA works better than the TS algorithm in terms of solution quality and, computationally, both LSA and TS are competitive.

  16. Exact Solutions to the Double Travelling Salesman Problem with Multiple Stacks

    DEFF Research Database (Denmark)

    Petersen, Hanne L.; Archetti, Claudia; Speranza, M. Grazia

    2010-01-01

    In this paper we present mathematical programming formulations and solution approaches for the optimal solution of the Double Travelling Salesman Problem with Multiple Stacks (DTSPMS). A set of orders is given, each one requiring transportation of one item from a customer in a pickup region...

  17. Well-solvable special cases of the Traveling Salesman Problem : a survey

    NARCIS (Netherlands)

    Burkard, R.E.; Deineko, V.G.; Dal, van R.; Veen, van der J.A.A.; Woeginger, G.J.

    1998-01-01

    The traveling salesman problem (TSP) belongs to the most basic, most important, and most investigated problems in combinatorial optimization. Although it is an ${\\cal NP}$-hard problem, many of its special cases can be solved efficiently in polynomial time. We survey these special cases with

  18. Human Performance on the Traveling Salesman and Related Problems: A Review

    Science.gov (United States)

    MacGregor, James N.; Chu, Yun

    2011-01-01

    The article provides a review of recent research on human performance on the traveling salesman problem (TSP) and related combinatorial optimization problems. We discuss what combinatorial optimization problems are, why they are important, and why they may be of interest to cognitive scientists. We next describe the main characteristics of human…

  19. The double travelling salesman problem with multiple stacks - Formulation and heuristic solution approaches

    DEFF Research Database (Denmark)

    Petersen, Hanne Løhmann; Madsen, Oli B.G.

    2009-01-01

    This paper introduces the double travelling salesman problem with multiple stacks and presents four different metaheuristic approaches to its solution. The double TSP with multiple stacks is concerned with determining the shortest route performing pickups and deliveries in two separated networks...

  20. THE TRAVELLING SALESMAN PROBLEM IN THE ENGINEERING EDUCATION PROGRAMMING CURRICULUM

    OpenAIRE

    Yevgeny Gayev; Vadim Kalmikov

    2017-01-01

    Objective: To make students familiar with the famous Traveling Salesman Problem (TSP) and suggest the latter to become a common exercise in engineering programming curriculum provided the students master computer science in the easy programming environment MATLAB. Methods: easy programming in MATLAB makes true such modern educational approach as “discovery based” methodology. Results: a MATLAB TSP-program oriented to Ukrainian map is suggested that allows to pictorially demonstrate the proces...

  1. The cost-constrained traveling salesman problem

    Energy Technology Data Exchange (ETDEWEB)

    Sokkappa, P.R.

    1990-10-01

    The Cost-Constrained Traveling Salesman Problem (CCTSP) is a variant of the well-known Traveling Salesman Problem (TSP). In the TSP, the goal is to find a tour of a given set of cities such that the total cost of the tour is minimized. In the CCTSP, each city is given a value, and a fixed cost-constraint is specified. The objective is to find a subtour of the cities that achieves maximum value without exceeding the cost-constraint. Thus, unlike the TSP, the CCTSP requires both selection and sequencing. As a consequence, most results for the TSP cannot be extended to the CCTSP. We show that the CCTSP is NP-hard and that no K-approximation algorithm or fully polynomial approximation scheme exists, unless P = NP. We also show that several special cases are polynomially solvable. Algorithms for the CCTSP, which outperform previous methods, are developed in three areas: upper bounding methods, exact algorithms, and heuristics. We found that a bounding strategy based on the knapsack problem performs better, both in speed and in the quality of the bounds, than methods based on the assignment problem. Likewise, we found that a branch-and-bound approach using the knapsack bound was superior to a method based on a common branch-and-bound method for the TSP. In our study of heuristic algorithms, we found that, when selecting modes for inclusion in the subtour, it is important to consider the neighborhood'' of the nodes. A node with low value that brings the subtour near many other nodes may be more desirable than an isolated node of high value. We found two types of repetition to be desirable: repetitions based on randomization in the subtour buildings process, and repetitions encouraging the inclusion of different subsets of the nodes. By varying the number and type of repetitions, we can adjust the computation time required by our method to obtain algorithms that outperform previous methods.

  2. Optimization Approaches for the Traveling Salesman Problem with Drone

    OpenAIRE

    Agatz, N.A.H.; Bouman, P.C.; Schmidt, M.E.

    2016-01-01

    textabstractThe fast and cost-efficient home delivery of goods ordered online is logistically challenging. Many companies are looking for new ways to cross the last-mile to their customers. One technology-enabled opportunity that recently has received much at- tention is the use of a drone to support deliveries. An innovative last-mile delivery concept in which a truck collaborates with a drone to make deliveries gives rise to a new variant of the traveling salesman problem (TSP) that we call...

  3. Quantum elastic net and the traveling salesman problem

    International Nuclear Information System (INIS)

    Kostenko, B.F.; Pribis, J.; Yur'ev, M.Z.

    2009-01-01

    Theory of computer calculations strongly depends on the nature of elements the computer is made of. Quantum interference allows one to formulate the Shor factorization algorithm turned out to be more effective than any one written for classical computers. Similarly, quantum wave packet reduction allows one to devise the Grover search algorithm which outperforms any classical one. In the present paper we argue that the quantum incoherent tunneling can be used for elaboration of new algorithms able to solve some NP-hard problems, such as the traveling Salesman Problem, considered to be intractable in the classical theory of computer computations

  4. Dynamic Programming Approaches for the Traveling Salesman Problem with Drone

    OpenAIRE

    Bouman, Paul; Agatz, Niels; Schmidt, Marie

    2017-01-01

    markdownabstractA promising new delivery model involves the use of a delivery truck that collaborates with a drone to make deliveries. Effectively combining a drone and a truck gives rise to a new planning problem that is known as the Traveling Salesman Problem with Drone (TSP-D). This paper presents an exact solution approach for the TSP-D based on dynamic programming and present experimental results of different dynamic programming based heuristics. Our numerical experiments show that our a...

  5. Ant Colony Optimization ACO For The Traveling Salesman Problem TSP Using Partitioning

    Directory of Open Access Journals (Sweden)

    Alok Bajpai

    2015-08-01

    Full Text Available Abstract An ant colony optimization is a technique which was introduced in 1990s and which can be applied to a variety of discrete combinatorial optimization problem and to continuous optimization. The ACO algorithm is simulated with the foraging behavior of the real ants to find the incremental solution constructions and to realize a pheromone laying-and-following mechanism. This pheromone is the indirect communication among the ants. In this paper we introduces the partitioning technique based on the divide and conquer strategy for the traveling salesman problem which is one of the most important combinatorial problem in which the original problem is partitioned into the group of sub problems. And then we apply the ant colony algorithm using candidate list strategy for each smaller sub problems. After that by applying the local optimization and combining the sub problems to find the good solution for the original problem by improving the exploration efficiency of the ants. At the end of this paper we have also be presented the comparison of result with the normal ant colony system for finding the optimal solution to the traveling salesman problem.

  6. Penanganan Fuzzy Time Window pada Travelling Salesman Problem (TSP dengan Penerapan Algoritma Genetika

    Directory of Open Access Journals (Sweden)

    Gusti Eka Yuliastuti

    2017-03-01

    Full Text Available The route of the travel tour packages offered by travel agents is not considered optimum, so the level of satisfaction the tourist is not maximal. Selection of the route of the travel packages included in the traveling salesman problem (TSP. The problem that occurs is uncertain tourists visiting destinations at the best destinations timing hereinafter be referred to as the fuzzy time window problem. Therefore, the authors apply the genetic algorithm to solve the problem. Based on test results obtained optimum solution with the fitness value of 1.3291, a population size of 100, the number of generations of 1000, a combination of CR=0,4 and MR=0.6.

  7. Efficient Constraint Handling in Electromagnetism-Like Algorithm for Traveling Salesman Problem with Time Windows

    Science.gov (United States)

    Yurtkuran, Alkın

    2014-01-01

    The traveling salesman problem with time windows (TSPTW) is a variant of the traveling salesman problem in which each customer should be visited within a given time window. In this paper, we propose an electromagnetism-like algorithm (EMA) that uses a new constraint handling technique to minimize the travel cost in TSPTW problems. The EMA utilizes the attraction-repulsion mechanism between charged particles in a multidimensional space for global optimization. This paper investigates the problem-specific constraint handling capability of the EMA framework using a new variable bounding strategy, in which real-coded particle's boundary constraints associated with the corresponding time windows of customers, is introduced and combined with the penalty approach to eliminate infeasibilities regarding time window violations. The performance of the proposed algorithm and the effectiveness of the constraint handling technique have been studied extensively, comparing it to that of state-of-the-art metaheuristics using several sets of benchmark problems reported in the literature. The results of the numerical experiments show that the EMA generates feasible and near-optimal results within shorter computational times compared to the test algorithms. PMID:24723834

  8. Efficient Constraint Handling in Electromagnetism-Like Algorithm for Traveling Salesman Problem with Time Windows

    Directory of Open Access Journals (Sweden)

    Alkın Yurtkuran

    2014-01-01

    Full Text Available The traveling salesman problem with time windows (TSPTW is a variant of the traveling salesman problem in which each customer should be visited within a given time window. In this paper, we propose an electromagnetism-like algorithm (EMA that uses a new constraint handling technique to minimize the travel cost in TSPTW problems. The EMA utilizes the attraction-repulsion mechanism between charged particles in a multidimensional space for global optimization. This paper investigates the problem-specific constraint handling capability of the EMA framework using a new variable bounding strategy, in which real-coded particle’s boundary constraints associated with the corresponding time windows of customers, is introduced and combined with the penalty approach to eliminate infeasibilities regarding time window violations. The performance of the proposed algorithm and the effectiveness of the constraint handling technique have been studied extensively, comparing it to that of state-of-the-art metaheuristics using several sets of benchmark problems reported in the literature. The results of the numerical experiments show that the EMA generates feasible and near-optimal results within shorter computational times compared to the test algorithms.

  9. Heuristic methods using grasp, path relinking and variable neighborhood search for the clustered traveling salesman problem

    Directory of Open Access Journals (Sweden)

    Mário Mestria

    2013-08-01

    Full Text Available The Clustered Traveling Salesman Problem (CTSP is a generalization of the Traveling Salesman Problem (TSP in which the set of vertices is partitioned into disjoint clusters and objective is to find a minimum cost Hamiltonian cycle such that the vertices of each cluster are visited contiguously. The CTSP is NP-hard and, in this context, we are proposed heuristic methods for the CTSP using GRASP, Path Relinking and Variable Neighborhood Descent (VND. The heuristic methods were tested using Euclidean instances with up to 2000 vertices and clusters varying between 4 to 150 vertices. The computational tests were performed to compare the performance of the heuristic methods with an exact algorithm using the Parallel CPLEX software. The computational results showed that the hybrid heuristic method using VND outperforms other heuristic methods.

  10. On the Equivalence between some Local and Global Chinese Postman and Traveling Salesman Graphs

    NARCIS (Netherlands)

    Granot, D.; Hamers, H.J.M.

    2000-01-01

    A connected graph G=(V,E), a vertex in V and a non-negative weight function defined on Ecan be used to induce Chinese postman and traveling salesman (cooperative) games. A graph G=(V,E) is said to be locally (respectively, globally) Chinese postman balanced (respectively, totally balanced,

  11. Analysis of travelling salesman problem

    Science.gov (United States)

    Ahmed, Belal; Singh Chouhan, Shivank; Biswas, Subham; Gayathri, P.; Santhi, H.

    2017-11-01

    The multiple Traveling Salesman Problem (mTSP) is the general type of TSP, in which at least one than one sales representatives can be utilized as a part of the arrangement set. The Constraint in the improvement undertaking is that every sales representative comes back to beginning stage at end of outing, heading out to a particular arrangement of urban areas in the middle of and with the exception of the first, every last city is gone to by precisely one sales representative. The thought is to scan for the briefest course that is the slightest separation required for every salesperson to go from the beginning area to individual urban areas and back to the area from where he has begun. It is an intricate NP-Hard issue and has different applications for the most part in the field of planning and steering. The measure of algorithm time to take care of this issue develops exponentially as number of urban areas builds thus, the meta-heuristic streamlining algorithms, for example, Genetic Algorithm (GAs) are should have been investigated. The objective of this paper is to discover different algorithms utilized as a part of writing to understand mTSP.

  12. Facets for the Cardinality Constrained Quadratic Knapsack Problem and the Quadratic Selective Travelling Salesman Problem

    DEFF Research Database (Denmark)

    Mak, Vicky; Thomadsen, Tommy

    2004-01-01

    A well-known extension of the Travelling Salesman Problem (TSP) is the Selective (or Prize-collecting) TSP: In addition to the edge-costs, each node has an associated reward (denoted the node-reward) and instead of visiting all nodes, only profitable nodes are visited. The Quadratic Selective TSP...

  13. An Efficient Combined Meta-Heuristic Algorithm for Solving the Traveling Salesman Problem

    Directory of Open Access Journals (Sweden)

    Majid Yousefikhoshbakht

    2016-08-01

    Full Text Available The traveling salesman problem (TSP is one of the most important NP-hard Problems and probably the most famous and extensively studied problem in the field of combinatorial optimization. In this problem, a salesman is required to visit each of n given nodes once and only once, starting from any node and returning to the original place of departure. This paper presents an efficient evolutionary optimization algorithm developed through combining imperialist competitive algorithm and lin-kernighan algorithm called (MICALK in order to solve the TSP. The MICALK is tested on 44 TSP instances involving from 24 to 1655 nodes from the literature so that 26 best known solutions of the benchmark problem are also found by our algorithm. Furthermore, the performance of MICALK is compared with several metaheuristic algorithms, including GA, BA, IBA, ICA, GSAP, ABO, PSO and BCO on 32 instances from TSPLIB. The results indicate that the MICALK performs well and is quite competitive with the above algorithms.

  14. Large neighborhood search for the double traveling salesman problem with multiple stacks

    Energy Technology Data Exchange (ETDEWEB)

    Bent, Russell W [Los Alamos National Laboratory; Van Hentenryck, Pascal [BROWN UNIV

    2009-01-01

    This paper considers a complex real-life short-haul/long haul pickup and delivery application. The problem can be modeled as double traveling salesman problem (TSP) in which the pickups and the deliveries happen in the first and second TSPs respectively. Moreover, the application features multiple stacks in which the items must be stored and the pickups and deliveries must take place in reserve (LIFO) order for each stack. The goal is to minimize the total travel time satisfying these constraints. This paper presents a large neighborhood search (LNS) algorithm which improves the best-known results on 65% of the available instances and is always within 2% of the best-known solutions.

  15. A multiobjective non-dominated sorting genetic algorithm (NSGA-II for the Multiple Traveling Salesman Problem

    Directory of Open Access Journals (Sweden)

    Rubén Iván Bolaños

    2015-06-01

    Full Text Available This paper considers a multi-objective version of the Multiple Traveling Salesman Problem (MOmTSP. In particular, two objectives are considered: the minimization of the total traveled distance and the balance of the working times of the traveling salesmen. The problem is formulated as an integer multi-objective optimization model. A non-dominated sorting genetic algorithm (NSGA-II is proposed to solve the MOmTSP. The solution scheme allows one to find a set of ordered solutions in Pareto fronts by considering the concept of dominance. Tests on real world instances and instances adapted from the literature show the effectiveness of the proposed algorithm.

  16. An Enhanced Genetic Algorithm for the Generalized Traveling Salesman Problem

    Directory of Open Access Journals (Sweden)

    H. Jafarzadeh

    2017-12-01

    Full Text Available The generalized traveling salesman problem (GTSP deals with finding the minimum-cost tour in a clustered set of cities. In this problem, the traveler is interested in finding the best path that goes through all clusters. As this problem is NP-hard, implementing a metaheuristic algorithm to solve the large scale problems is inevitable. The performance of these algorithms can be intensively promoted by other heuristic algorithms. In this study, a search method is developed that improves the quality of the solutions and competition time considerably in comparison with Genetic Algorithm. In the proposed algorithm, the genetic algorithms with the Nearest Neighbor Search (NNS are combined and a heuristic mutation operator is applied. According to the experimental results on a set of standard test problems with symmetric distances, the proposed algorithm finds the best solutions in most cases with the least computational time. The proposed algorithm is highly competitive with the published until now algorithms in both solution quality and running time.

  17. Double evolutsional artificial bee colony algorithm for multiple traveling salesman problem

    Directory of Open Access Journals (Sweden)

    Xue Ming Hao

    2016-01-01

    Full Text Available The double evolutional artificial bee colony algorithm (DEABC is proposed for solving the single depot multiple traveling salesman problem (MTSP. The proposed DEABC algorithm, which takes advantage of the strength of the upgraded operators, is characterized by its guidance in exploitation search and diversity in exploration search. The double evolutional process for exploitation search is composed of two phases of half stochastic optimal search, and the diversity generating operator for exploration search is used for solutions which cannot be improved after limited times. The computational results demonstrated the superiority of our algorithm over previous state-of-the-art methods.

  18. TUTORIALS ON AFRICAN BUFFALO OPTIMIZATION FOR SOLVING THE TRAVELLING SALESMAN PROBLEM

    Directory of Open Access Journals (Sweden)

    Odili J.B

    2017-03-01

    Full Text Available The African Buffalo Optimization is a newly designed metaheuristic optimization algorithm inspired by the migration of African buffalos from place to place across the vast African forests, deserts and savannah in search of food. Being a new algorithm, several researchers from different parts of the research world have indicated huge interest in understanding the working of the novel algorithm. This paper presents a practical demonstration of the workings of the African Buffalo Optimization in solving the popular travelling salesman problem. It is our belief that this tutorial paper will be helpful in further introducing the new algorithm and making it user-friendly.

  19. Using 2-Opt based evolution strategy for travelling salesman problem

    Directory of Open Access Journals (Sweden)

    Kenan Karagul

    2016-03-01

    Full Text Available Harmony search algorithm that matches the (µ+1 evolution strategy, is a heuristic method simulated by the process of music improvisation. In this paper, a harmony search algorithm is directly used for the travelling salesman problem. Instead of conventional selection operators such as roulette wheel, the transformation of real number values of harmony search algorithm to order index of vertex representation and improvement of solutions are obtained by using the 2-Opt local search algorithm. Then, the obtained algorithm is tested on two different parameter groups of TSPLIB. The proposed method is compared with classical 2-Opt which randomly started at each step and best known solutions of test instances from TSPLIB. It is seen that the proposed algorithm offers valuable solutions.

  20. A population-based algorithm for the multi travelling salesman problem

    Directory of Open Access Journals (Sweden)

    Rubén Iván Bolaños

    2016-04-01

    Full Text Available This paper presents the implementation of an efficient modified genetic algorithm for solving the multi-traveling salesman problem (mTSP. The main characteristics of the method are the construction of an initial population of high quality and the implementation of several local search operators which are important in the efficient and effective exploration of promising regions of the solution space. Due to the combinatorial complexity of mTSP, the proposed methodology is especially applicable for real-world problems. The proposed algorithm was tested on a set of six benchmark instances, which have from 76 and 1002 cities to be visited. In all cases, the best known solution was improved. The results are also compared with other existing solutions procedure in the literature.

  1. PEMANFAATAN TEKNOLOGI GOOGLE MAPS UNTUK PENYELESAIAN ONLINE TRAVELLING SALESMAN PROBLEM (TSP BERBASIS GEOGRAFIS DENGAN MENGGUNAKAN ALGORITMA HEURISTIK

    Directory of Open Access Journals (Sweden)

    Wahyudi Agustiono

    2010-07-01

    Full Text Available Travelling Salesman Problem (TSP adalah salah satu metode klasik dalam proses pemecahan masalah optimasi dan penemuan rute terpendek dari sebuah rute perjalanan yang melewati beberapa titik lokasi. Oleh karena kehandalan metode ini banyak sekali algoritma dan metode optimasi yang mencoba memecahkan TSP dalam banyak penelitian. Sebagin besar hasil dari rangkaian ujicoba tersebut berupa kombinasi teroptimal dari rangkaian perjalanan salesman yang umumnya digambarkan dalam sebuah graph. Namun belum banyak penelitian yang menerapkan TSP pada data spasial atau geografis seperti Google Maps yang dapat memberikan representasi nyata permasalahan TSP dalam menemukan rute perjalanan melewati titik-titik wilayah di muka bumi. Dibandingkan dengan representasi graph, Google Maps memiliki kemampuan tidak sekedar menampilkan rute perjalanan akan tetapi juga dapat menyajikan informasi yang lebih komprehensif, interaktif dan faktual. Penelitian ini bertujuan untuk menerapkan metode TSP pada layanan data spasial sehingga akan dihasilkan visualisasi secara riil dari alternatif rute perjalanan salesman. Sebagai basis dari data spasial, penelitian ini memanfaatkan Google Maps Mashup untuk mendapatkan informasi rute yang lebih aktual, interaktif, dan komprehensif.

  2. ON SAMPLING BASED METHODS FOR THE DUBINS TRAVELING SALESMAN PROBLEM WITH NEIGHBORHOODS

    Directory of Open Access Journals (Sweden)

    Petr Váňa

    2015-12-01

    Full Text Available In this paper, we address the problem of path planning to visit a set of regions by Dubins vehicle, which is also known as the Dubins Traveling Salesman Problem Neighborhoods (DTSPN. We propose a modification of the existing sampling-based approach to determine increasing number of samples per goal region and thus improve the solution quality if a more computational time is available. The proposed modification of the sampling-based algorithm has been compared with performance of existing approaches for the DTSPN and results of the quality of the found solutions and the required computational time are presented in the paper.

  3. List-Based Simulated Annealing Algorithm for Traveling Salesman Problem

    Directory of Open Access Journals (Sweden)

    Shi-hua Zhan

    2016-01-01

    Full Text Available Simulated annealing (SA algorithm is a popular intelligent optimization algorithm which has been successfully applied in many fields. Parameters’ setting is a key factor for its performance, but it is also a tedious work. To simplify parameters setting, we present a list-based simulated annealing (LBSA algorithm to solve traveling salesman problem (TSP. LBSA algorithm uses a novel list-based cooling schedule to control the decrease of temperature. Specifically, a list of temperatures is created first, and then the maximum temperature in list is used by Metropolis acceptance criterion to decide whether to accept a candidate solution. The temperature list is adapted iteratively according to the topology of the solution space of the problem. The effectiveness and the parameter sensitivity of the list-based cooling schedule are illustrated through benchmark TSP problems. The LBSA algorithm, whose performance is robust on a wide range of parameter values, shows competitive performance compared with some other state-of-the-art algorithms.

  4. Discrete Teaching-learning-based optimization Algorithm for Traveling Salesman Problems

    Directory of Open Access Journals (Sweden)

    Wu Lehui

    2017-01-01

    Full Text Available In this paper, a discrete variant of TLBO (DTLBO is proposed for solving the traveling salesman problem (TSP. In the proposed method, an effective learner representation scheme is redefined based on the characteristics of TSP problem. Moreover, all learners are randomly divided into several sub-swarms with equal amounts of learners so as to increase the diversity of population and reduce the probability of being trapped in local optimum. In each sub-swarm, the new positions of learners in the teaching phase and the learning phase are generated by the crossover operation, the legality detection and mutation operation, and then the offspring learners are determined based on greedy selection. Finally, to verify the performance of the proposed algorithm, benchmark TSP problems are examined and the results indicate that DTLBO is effective compared with other algorithms used for TSP problems.

  5. Global approach to the n-dimensional traveling salesman problem: Application to the optimization of crystallographic data collection

    Energy Technology Data Exchange (ETDEWEB)

    Weinrach, J.B.; Bennett, D.W.

    1987-12-01

    An algorithm for the optimization of data collection time has been written and a subsequent computer program tested for diffractometer systems. The program, which utilizes a global statistical approach to the traveling salesman problem, yields reasonable solutions in a relatively short time. The algorithm has been successful in treating very large data sets (up to 4000 points) in three dimensions with subsequent time savings of ca 30%.

  6. How Much is Location Information Worth? A Competitive Analysis of the Online Traveling Salesman Problem with Two Disclosure Dates

    NARCIS (Netherlands)

    F.J. Srour (Jordan); R.A. Zuidwijk (Rob)

    2008-01-01

    textabstractIn this paper we derive the worst-case ratio of an online algorithm for the Traveling Salesman Problem (TSP) with two disclosure dates. This problem, a variant of the online TSP with release dates, is characterized by the disclosure of a job’s location at one point in time followed by

  7. Optimization of travel salesman problem using the ant colony system and Greedy search

    International Nuclear Information System (INIS)

    Esquivel E, J.; Ordonez A, A.; Ortiz S, J. J.

    2008-01-01

    In this paper we present some results obtained during the development of optimization systems that can be used to design refueling and patterns of control rods in a BWR. These systems use ant colonies and Greedy search. The first phase of this project is to be familiar with these optimization techniques applied to the problem of travel salesman problem (TSP). The utility of TSP study is that, like the refueling design and pattern design of control rods are problems of combinative optimization. Even, the similarity with the problem of the refueling design is remarkable. It is presented some results for the TSP with the 32 state capitals of Mexico country. (Author)

  8. Optimization of Multiple Traveling Salesman Problem Based on Simulated Annealing Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    Xu Mingji

    2017-01-01

    Full Text Available It is very effective to solve the multi variable optimization problem by using hierarchical genetic algorithm. This thesis analyzes both advantages and disadvantages of hierarchical genetic algorithm and puts forward an improved simulated annealing genetic algorithm. The new algorithm is applied to solve the multiple traveling salesman problem, which can improve the performance of the solution. First, it improves the design of chromosomes hierarchical structure in terms of redundant hierarchical algorithm, and it suggests a suffix design of chromosomes; Second, concerning to some premature problems of genetic algorithm, it proposes a self-identify crossover operator and mutation; Third, when it comes to the problem of weak ability of local search of genetic algorithm, it stretches the fitness by mixing genetic algorithm with simulated annealing algorithm. Forth, it emulates the problems of N traveling salesmen and M cities so as to verify its feasibility. The simulation and calculation shows that this improved algorithm can be quickly converged to a best global solution, which means the algorithm is encouraging in practical uses.

  9. Perancangan Aplikasi Penjadwalan Traveling Salesman Problem dengan Algoritma Genetika

    Directory of Open Access Journals (Sweden)

    Hendy Tannady

    2012-12-01

    Full Text Available Supply chain management plays an important role in enhancing the efficiency and effectiveness of manufacturing industry business process. In this research, the problem is taken from a sales division in a company in determining the optimal sequence when delivering goods into nine cities. This problem is oftenreferred as travelling salesman problem. This problem is considered important since the optimal sequence can cut off operational cost. Creating an artificial intelligence for the company in determining the location and the optimal sequence of delivering goods is the main objective of this research. A genetic algorithm is utilized to determine the location and the optimal sequence. While for processing the data and concluding the result, researcher designed a Java-based application that provides the capability of automatic computing. The result of this computation is a sequence of locations with a fitness number for each. The best fitness number for the sequence location will be used for the final result and the conclusion to answer the company’s problem.

  10. Solution for a bipartite Euclidean traveling-salesman problem in one dimension

    Science.gov (United States)

    Caracciolo, Sergio; Di Gioacchino, Andrea; Gherardi, Marco; Malatesta, Enrico M.

    2018-05-01

    The traveling-salesman problem is one of the most studied combinatorial optimization problems, because of the simplicity in its statement and the difficulty in its solution. We characterize the optimal cycle for every convex and increasing cost function when the points are thrown independently and with an identical probability distribution in a compact interval. We compute the average optimal cost for every number of points when the distance function is the square of the Euclidean distance. We also show that the average optimal cost is not a self-averaging quantity by explicitly computing the variance of its distribution in the thermodynamic limit. Moreover, we prove that the cost of the optimal cycle is not smaller than twice the cost of the optimal assignment of the same set of points. Interestingly, this bound is saturated in the thermodynamic limit.

  11. Developing Programming Tools to Handle Traveling Salesman Problem by the Three Object-Oriented Languages

    Directory of Open Access Journals (Sweden)

    Hassan Ismkhan

    2014-01-01

    Full Text Available The traveling salesman problem (TSP is one of the most famous problems. Many applications and programming tools have been developed to handle TSP. However, it seems to be essential to provide easy programming tools according to state-of-the-art algorithms. Therefore, we have collected and programmed new easy tools by the three object-oriented languages. In this paper, we present ADT (abstract data type of developed tools at first; then we analyze their performance by experiments. We also design a hybrid genetic algorithm (HGA by developed tools. Experimental results show that the proposed HGA is comparable with the recent state-of-the-art applications.

  12. An new self-organizing maps strategy for solving the traveling salesman problem

    International Nuclear Information System (INIS)

    Bai Yanping; Zhang Wendong; Jin Zhen

    2006-01-01

    This paper presents an approach to the well-known traveling salesman problem (TSP) using self-organizing maps (SOM). There are many types of SOM algorithms to solve the TSP found in the literature, whereas the purpose of this paper is to look for the incorporation of an efficient initialization methods and the definition of a parameters adaptation law to achieve better results and a faster convergence. Aspects of parameters adaptation, selecting the number of nodes of neurons, index of winner neurons and effect of the initial ordering of the cities, as well as the initial synaptic weights of the modified SOM algorithm are discussed. The complexity of the modified SOM algorithm is analyzed. The simulated results show an average deviation of 2.32% from the optimal tour length for a set of 12 TSP instances

  13. An new self-organizing maps strategy for solving the traveling salesman problem

    Energy Technology Data Exchange (ETDEWEB)

    Bai Yanping [Key Lab of Instrument Science and Dynamic Measurement of Ministry of Education, North University of China, No. 3, Xueyuan Road, TaiYuan, ShanXi 030051 (China)]. E-mail: baiyp@nuc.edu.cn; Zhang Wendong [Key Lab of Instrument Science and Dynamic Measurement of Ministry of Education, North University of China, No. 3, Xueyuan Road, TaiYuan, ShanXi 030051 (China)]. E-mail: wdzhang@nuc.edu.cn; Jin Zhen [Department of Applied Mathematics, North University of China, No. 3 Xueyuan Road, TaiYuan, ShanXi 030051 (China)

    2006-05-15

    This paper presents an approach to the well-known traveling salesman problem (TSP) using self-organizing maps (SOM). There are many types of SOM algorithms to solve the TSP found in the literature, whereas the purpose of this paper is to look for the incorporation of an efficient initialization methods and the definition of a parameters adaptation law to achieve better results and a faster convergence. Aspects of parameters adaptation, selecting the number of nodes of neurons, index of winner neurons and effect of the initial ordering of the cities, as well as the initial synaptic weights of the modified SOM algorithm are discussed. The complexity of the modified SOM algorithm is analyzed. The simulated results show an average deviation of 2.32% from the optimal tour length for a set of 12 TSP instances.

  14. A Computational Analysis of the Traveling Salesman and Cutting Stock Problems

    Directory of Open Access Journals (Sweden)

    Gracia María D.

    2015-01-01

    Full Text Available The aim of this article is to perform a computational study to analyze the impact of formulations, and the solution strategy on the algorithmic performance of two classical optimization problems: the traveling salesman problem and the cutting stock problem. In order to assess the algorithmic performance on both problems three dependent variables were used: solution quality, computing time and number of iterations. The results are useful for choosing the solution approach to each specific problem. In the STSP, the results demonstrate that the multistage decision formulation is better than the conventional formulations, by solving 90.47% of the instances compared with MTZ (76.19% and DFJ (14.28%. The results of the CSP demonstrate that the cutting patterns formulation is better than the standard formulation with symmetry breaking inequalities, when the objective function is to minimize the loss of trim when cutting the rolls.

  15. An approach using quantum PBIL to solve the traveling salesman problem

    International Nuclear Information System (INIS)

    Silva, Marcio Henrique; Schirru, Roberto

    2011-01-01

    Quantum inspired evolutionary algorithms are optimization tools based in artificial intelligence developed to simulate the quantum processing in classical computers viewing that there are not quantum computers available nowadays. In this work is introduced one of these tools, which adds quantum concepts such as the linear superposition of states and the qubit representation to standard PBIL named Quantum PBIL. Here we use Quantum PBIL to solve a well-known NPHard benchmark, the Traveling salesman problem. The objective is to find the shorter path made by a traveler linking all the available cities visiting each one only once and returning to the starter one at the final of his journey. As the main purpose of this work is employ the algorithm to solve the nuclear reload optimization in the future, and according to the similarities that both problems share, TSP is a good challenge for Quantum PBIL. The results have shown that the algorithm is able to obtain good performance when applied on this problem. It is also fast and has a great capacity to find good solutions when compared to other versions of PBIL found in literature despite of its stagnation of bits tendency can easily lead it to local minimums. (author)

  16. An approach using quantum PBIL to solve the traveling salesman problem

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Marcio Henrique; Schirru, Roberto, E-mail: marciohenrique@lmp.ufrj.br, E-mail: schirru@lmp.ufrj.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (PEN/COPPE), Rio de Janeiro, RJ (Brazil)

    2011-07-01

    Quantum inspired evolutionary algorithms are optimization tools based in artificial intelligence developed to simulate the quantum processing in classical computers viewing that there are not quantum computers available nowadays. In this work is introduced one of these tools, which adds quantum concepts such as the linear superposition of states and the qubit representation to standard PBIL named Quantum PBIL. Here we use Quantum PBIL to solve a well-known NPHard benchmark, the Traveling salesman problem. The objective is to find the shorter path made by a traveler linking all the available cities visiting each one only once and returning to the starter one at the final of his journey. As the main purpose of this work is employ the algorithm to solve the nuclear reload optimization in the future, and according to the similarities that both problems share, TSP is a good challenge for Quantum PBIL. The results have shown that the algorithm is able to obtain good performance when applied on this problem. It is also fast and has a great capacity to find good solutions when compared to other versions of PBIL found in literature despite of its stagnation of bits tendency can easily lead it to local minimums. (author)

  17. Method for the traveling salesman problem by controlling two parameters of the Hopfield neural network; Parameter seigyogata hop field net ni yoru junkai salesman mondai no kaiho

    Energy Technology Data Exchange (ETDEWEB)

    Setsu, N.; Murakami, K.; Ohori, T.; Watanabe, K. [Hokkaido Institute of Technology, Sapporo (Japan)

    1996-01-20

    For solving the traveling salesman problem (TSP) by using a continuous value outputting neural net (NN), an investigation was given on the accuracy of solution and the possibility on traveling routes by using the penalty coefficient and temperature as the parameters for energy functions. The parameter range to obtain high-quality traveling routes was shown by a numerical experiment. The experimental result revealed that, when the penalty coefficient `r` is large, the traveling route possibility tends to become higher, but the route length increases, and when the `r` is small, the traveling route possibility becomes lower, but the route length decreases, also in the continuous value outputting NN as in the two-value outputting NN. Noticing this fact, and in order to improve the traveling route possibility as well as the solution quality, a method was proposed to expand the penalty control method which was proposed previously by the authors on the two-value outputting NN, into the continuous value outputting NN. In addition, a proposal was also made on a method to derive an optimal temperature efficiently by using the golden section method. It was found that the relative error has been reduced by 48% on the average as compared with that in the conventional method in which the temperature is fixed. 6 refs., 5 figs.

  18. Implementasi Algoritma Best-First Search (BeFS pada Penyelesaian Traveling Salesman Problem (TSP (Studi Kasus: Perjalanan Wisata Di Kota Yogyakarta

    Directory of Open Access Journals (Sweden)

    Muchammad Abrori

    2015-10-01

    Full Text Available Yogyakarta offers many tourist attractions, from nature based tourism, culinary tourism until cultural tourism. With so many tourist attractions offered by Yogyakarta, tourist often finds it difficult to arrange their travel schedule (from choosing which tourist attractions to be visited until choosing which route tourist should takes to maximize their vacation time. Therefore, it’s required to have a way to determine the shortest tour route so tourist can make their tour in the Yogyakarta effective. This problem can be categorized as Traveling Salesman Problem (TSP case. There are a lot of methods can be used to find the shortest route in Travelling Salesman Problems (TSP case. To solve the problem, which is to find the shortest tour route in Yogyakarta, Algorithm Best-First Travelling will be used in this undergraduate thesis. The implementation of Algorithm Best-First Search to find the shortest tour route in Yogyakarta can be used to produce a solution for tourist to choose the shortest tour package and decide which route they should take. The premium tour package produces tour route from Adi Sucipto Airport-Gembira Loka Zoo- Purawisata-N’dalem Gamelan Hotel-Yogyakarta Palace-Benteng Vredeburg Museum-Taman Pintar-Tamansari-Adi Sucipto Airport with distance covered 20.297 meter. The middle tour package produces tour route from Tugu railway station-Benteng Vredeburg Museum- Taman Pintar-Yogyakarta Palace-Mawar Asri Hotel-Tamansari-Purawisata-Gembira Loka Zoo-Tugu railway station with distance covered 11.772 meter. The economy tour package produces tour route from Giwangan bus station- Gembira Loka zoo-Purawisata-Yogyakarta Palace-Mitra Hotel-Benteng Vredeburg Museum-Taman Pintar-Tamansari-Giwangan bus station with distance covered 14.037 meter.

  19. Hierarchical Solution of the Traveling Salesman Problem with Random Dyadic Tilings

    Science.gov (United States)

    Kalmár-Nagy, Tamás; Bak, Bendegúz Dezső

    We propose a hierarchical heuristic approach for solving the Traveling Salesman Problem (TSP) in the unit square. The points are partitioned with a random dyadic tiling and clusters are formed by the points located in the same tile. Each cluster is represented by its geometrical barycenter and a “coarse” TSP solution is calculated for these barycenters. Midpoints are placed at the middle of each edge in the coarse solution. Near-optimal (or optimal) minimum tours are computed for each cluster. The tours are concatenated using the midpoints yielding a solution for the original TSP. The method is tested on random TSPs (independent, identically distributed points in the unit square) up to 10,000 points as well as on a popular benchmark problem (att532 — coordinates of 532 American cities). Our solutions are 8-13% longer than the optimal ones. We also present an optimization algorithm for the partitioning to improve our solutions. This algorithm further reduces the solution errors (by several percent using 1000 iteration steps). The numerical experiments demonstrate the viability of the approach.

  20. A High-Performance Genetic Algorithm: Using Traveling Salesman Problem as a Case

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    Chun-Wei Tsai

    2014-01-01

    Full Text Available This paper presents a simple but efficient algorithm for reducing the computation time of genetic algorithm (GA and its variants. The proposed algorithm is motivated by the observation that genes common to all the individuals of a GA have a high probability of surviving the evolution and ending up being part of the final solution; as such, they can be saved away to eliminate the redundant computations at the later generations of a GA. To evaluate the performance of the proposed algorithm, we use it not only to solve the traveling salesman problem but also to provide an extensive analysis on the impact it may have on the quality of the end result. Our experimental results indicate that the proposed algorithm can significantly reduce the computation time of GA and GA-based algorithms while limiting the degradation of the quality of the end result to a very small percentage compared to traditional GA.

  1. New formulation and branch-and-cut algorithm for the pickup and delivery traveling salesman problem with multiple stacks: new formulation and branch-and-cut algorithm

    NARCIS (Netherlands)

    Sampaio Oliveira, A.H.; Urrutia, S.

    2017-01-01

    In this paper, we consider the pickup and delivery traveling salesman problem with multiple stacks in which a single vehicle must serve a set of customer requests defined by a pair of pickup and delivery destinations of an item. The vehicle contains a fixed number of stacks, where each item is

  2. Performance analysis of the partial use of a local optimization operator on the genetic algorithm for the Travelling Salesman Problem

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    Milan Djordjevic

    2012-01-01

    Full Text Available Background: The Travelling Salesman Problem is an NP-hard problem in combinatorial optimization with a number of practical implications. There are many heuristic algorithms and exact methods for solving the problem. Objectives: In this paper we study the influence of hybridization of a genetic algorithm with a local optimizer on solving instances of the Travelling Salesman Problem. Methods/ Approach: Our algorithm uses hybridization that occurs at various percentages of generations of a genetic algorithm. Moreover, we have also studied at which generations to apply the hybridization and hence applied it at random generations, at the initial generations, and at the last ones. Results: We tested our algorithm on instances with sizes ranging from 76 to 439 cities. On the one hand, the less frequent application of hybridization decreased the average running time of the algorithm from 14.62 sec to 2.78 sec at 100% and 10% hybridization respectively, while on the other hand, the quality of the solution on average deteriorated only from 0.21% till 1.40% worse than the optimal solution. Conclusions: In the paper we have shown that even a small hybridization substantially improves the quality of the result. Moreover, the hybridization in fact does not deteriorate the running time too much. Finally, our experiments show that the best results are obtained when hybridization occurs in the last generations of the genetic algorithm.

  3. A combination of genetic algorithm and particle swarm optimization method for solving traveling salesman problem

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    Keivan Borna

    2015-12-01

    Full Text Available Traveling salesman problem (TSP is a well-established NP-complete problem and many evolutionary techniques like particle swarm optimization (PSO are used to optimize existing solutions for that. PSO is a method inspired by the social behavior of birds. In PSO, each member will change its position in the search space, according to personal or social experience of the whole society. In this paper, we combine the principles of PSO and crossover operator of genetic algorithm to propose a heuristic algorithm for solving the TSP more efficiently. Finally, some experimental results on our algorithm are applied in some instances in TSPLIB to demonstrate the effectiveness of our methods which also show that our algorithm can achieve better results than other approaches.

  4. The Multi-commodity One-to-one Pickup-and-delivery Traveling Salesman Problem with Path Duration Limits

    DEFF Research Database (Denmark)

    Plum, Christian Edinger Munk; Pisinger, David; Salazar-González, Juan-José

    2012-01-01

    The design of container shipping networks is an important real world problem, with assets and operational costs in billions of dollars. To guide the optimal deployment of the ships, a single vessel roundtrip is considered by minimizing operational costs and flowing the best paying cargo under...... commercial constraints. Inspiration for formulation and solution method is taken from the rich research done within pickup and delivery problems. The problem, the multicommodity one-toone pickup and delivery traveling salesman problem with path duration limits is, to the best of out knowledge, considered...... for the first time. An arc flow and a path flow model are presented. A Branch and Cut and Price solution method is proposed and implemented....

  5. THE TRAVELLING SALESMAN PROBLEM IN THE ENGINEERING EDUCATION PROGRAMMING CURRICULUM

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    Yevgeny Gayev

    2017-11-01

    Full Text Available Objective: To make students familiar with the famous Traveling Salesman Problem (TSP and suggest the latter to become a common exercise in engineering programming curriculum provided the students master computer science in the easy programming environment MATLAB. Methods: easy programming in MATLAB makes true such modern educational approach as “discovery based” methodology. Results: a MATLAB TSP-program oriented to Ukrainian map is suggested that allows to pictorially demonstrate the process of optimal route search with an option to decelerate or accelerate the demonstration. The program is guessed to be useful both for learning the TSP as one of fundamental logistics problems and as an intriguing programming curriculum excersize. Several sub-programs according to key stone Computer Science Curriculum have also been suggested. This lies in line with recent “discovery based” learning methodology. Discussion: we explain how to create this program for visual discrete optimization, suggest required subprograms belonging to key stone programming algorithms including rather modern graphical user interface (GUI, how to use this MATLAB TSP-program for demonstration the drastical grows of solution time required. Conclusions: easy programming being realized in MATLAB makes dificult curriculum problems attractive to students; it focuses them to main problem’ features, laws and algorithms implementing the “discovery based” methodology in such a way.

  6. Solving Arc Routing Problems Using the Lin-Kernighan-Helsgaun Algorithm

    DEFF Research Database (Denmark)

    Helsgaun, Keld

    It is well known that many arc routing problems can be transformed into the Equality Generalized Traveling Salesman Problem (E-GTSP), which in turn can be transformed into a standard Asymmetric Traveling Salesman Problem (TSP). This opens up the possibility of solving arc routing problems using...

  7. Advanced Harmony Search with Ant Colony Optimization for Solving the Traveling Salesman Problem

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    Ho-Yoeng Yun

    2013-01-01

    Full Text Available We propose a novel heuristic algorithm based on the methods of advanced Harmony Search and Ant Colony Optimization (AHS-ACO to effectively solve the Traveling Salesman Problem (TSP. The TSP, in general, is well known as an NP-complete problem, whose computational complexity increases exponentially by increasing the number of cities. In our algorithm, Ant Colony Optimization (ACO is used to search the local optimum in the solution space, followed by the use of the Harmony Search to escape the local optimum determined by the ACO and to move towards a global optimum. Experiments were performed to validate the efficiency of our algorithm through a comparison with other algorithms and the optimum solutions presented in the TSPLIB. The results indicate that our algorithm is capable of generating the optimum solution for most instances in the TSPLIB; moreover, our algorithm found better solutions in two cases (kroB100 and pr144 when compared with the optimum solution presented in the TSPLIB.

  8. A GPU Implementation of Local Search Operators for Symmetric Travelling Salesman Problem

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    Juraj Fosin

    2013-06-01

    Full Text Available The Travelling Salesman Problem (TSP is one of the most studied combinatorial optimization problem which is significant in many practical applications in transportation problems. The TSP problem is NP-hard problem and requires large computation power to be solved by the exact algorithms. In the past few years, fast development of general-purpose Graphics Processing Units (GPUs has brought huge improvement in decreasing the applications’ execution time. In this paper, we implement 2-opt and 3-opt local search operators for solving the TSP on the GPU using CUDA. The novelty presented in this paper is a new parallel iterated local search approach with 2-opt and 3-opt operators for symmetric TSP, optimized for the execution on GPUs. With our implementation large TSP problems (up to 85,900 cities can be solved using the GPU. We will show that our GPU implementation can be up to 20x faster without losing quality for all TSPlib problems as well as for our CRO TSP problem.

  9. Improved Genetic and Simulating Annealing Algorithms to Solve the Traveling Salesman Problem Using Constraint Programming

    Directory of Open Access Journals (Sweden)

    M. Abdul-Niby

    2016-04-01

    Full Text Available The Traveling Salesman Problem (TSP is an integer programming problem that falls into the category of NP-Hard problems. As the problem become larger, there is no guarantee that optimal tours will be found within reasonable computation time. Heuristics techniques, like genetic algorithm and simulating annealing, can solve TSP instances with different levels of accuracy. Choosing which algorithm to use in order to get a best solution is still considered as a hard choice. This paper suggests domain reduction as a tool to be combined with any meta-heuristic so that the obtained results will be almost the same. The hybrid approach of combining domain reduction with any meta-heuristic encountered the challenge of choosing an algorithm that matches the TSP instance in order to get the best results.

  10. Kombinasi Firefly Algorithm-Tabu Search untuk Penyelesaian Traveling Salesman Problem

    Directory of Open Access Journals (Sweden)

    Riyan Naufal Hay's

    2017-07-01

    Full Text Available Traveling Salesman Problem (TSP adalah masalah optimasi kombinatorial klasik dan memiliki peran dalam perencanaan, penjadwalan, dan pencarian pada bidang rekayasa dan pengetahuan (Dong, 2012. TSP juga merupakan objek yang baik untuk menguji kinerja metode optimasi, beberapa metode seperti Cooperative Genetic Ant System (CGAS (Dong, 2012, Parallelized Genetic Ant Colony System (PGAS Particle Swarm Optimization and Ant Colony Optimization Algorithms (PSO–ACO (Elloumi, 2014, dan Ant Colony Hyper-Heuristics (ACO HH (Aziz, 2015 telah dikembangkan untuk memecahkan TSP. Sehingga, pada penelitian ini diimplementasikan kombinasi metode baru untuk meningkatkan akurasi penyelesaian TSP. Firefly Algorithm (FA merupakan salah satu algoritma yang dapat digunakan untuk memecahkan masalah optimasi kombinatorial (Layeb, 2014. FA merupakan algoritma yang berpotensi kuat dalam memecahkan kasus optimasi dibanding algoritma yang ada termasuk Particle Swarm Optimization (Yang, 2010. Namun, FA memiliki kekurangan dalam memecahkan masalah optimasi dengan skala besar (Baykasoğlu dan Ozsoy, 2014. Tabu Search (TS merupakan metode optimasi yang terbukti efektif untuk memecahkan masalah optimasi dengan skala besar (Pedro, 2013. Pada penelitian ini, TS akan diterapkan pada FA (FATS untuk memecahkan kasus TSP. Hasil FATS akan dibandingkan terhadap penelitian sebelumnya yaitu ACOHH. Perbandingan hasil menunjukan peningkatan akurasi sebesar 0.89% pada dataset Oliver30, 0.14% dataset Eil51, 3.81% dataset Eil76 dan 1.27% dataset KroA100.

  11. Solving the Traveling Salesman Problem Based on The Genetic Reactive Bone Route Algorithm whit Ant Colony System

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    Majid Yousefikhoshbakht

    2016-07-01

    Full Text Available The TSP is considered one of the most well-known combinatorial optimization tasks and researchers have paid so much attention to the TSP for many years. In this problem, a salesman starts to move from an arbitrary place called depot and after visits all of the nodes, finally comes back to the depot. The objective is to minimize the total distance traveled by the salesman.  Because this problem is a non-deterministic polynomial (NP-hard problem in nature, a hybrid meta-heuristic algorithm called REACSGA is used for solving the TSP. In REACSGA, a reactive bone route algorithm that uses the ant colony system (ACS for generating initial diversified solutions and the genetic algorithm (GA as an improved procedure are applied. Since the performance of the Metaheuristic algorithms is significantly influenced by their parameters, Taguchi Method is used to set the parameters of the proposed algorithm. The proposed algorithm is tested on several standard instances involving 24 to 318 nodes from the literature. The computational result shows that the results of the proposed algorithm are competitive with other metaheuristic algorithms for solving the TSP in terms of better quality of solution and computational time respectively. In addition, the proposed REACSGA is significantly efficient and finds closely the best known solutions for most of the instances in which thirteen best known solutions are also found.

  12. A Discrete Fruit Fly Optimization Algorithm for the Traveling Salesman Problem.

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    Zi-Bin Jiang

    Full Text Available The fruit fly optimization algorithm (FOA is a newly developed bio-inspired algorithm. The continuous variant version of FOA has been proven to be a powerful evolutionary approach to determining the optima of a numerical function on a continuous definition domain. In this study, a discrete FOA (DFOA is developed and applied to the traveling salesman problem (TSP, a common combinatorial problem. In the DFOA, the TSP tour is represented by an ordering of city indices, and the bio-inspired meta-heuristic search processes are executed with two elaborately designed main procedures: the smelling and tasting processes. In the smelling process, an effective crossover operator is used by the fruit fly group to search for the neighbors of the best-known swarm location. During the tasting process, an edge intersection elimination (EXE operator is designed to improve the neighbors of the non-optimum food location in order to enhance the exploration performance of the DFOA. In addition, benchmark instances from the TSPLIB are classified in order to test the searching ability of the proposed algorithm. Furthermore, the effectiveness of the proposed DFOA is compared to that of other meta-heuristic algorithms. The results indicate that the proposed DFOA can be effectively used to solve TSPs, especially large-scale problems.

  13. Solusi Optimal Model Optimisasi Robust Untuk Masalah Traveling Salesman Dengan Ketidaktentuan Kotak Dan Pendekatan Metode Branch And Bound

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    Poppy Amriyati

    2015-12-01

    Full Text Available Traveling Salesman Problem (TSP merupakan teknik pencarian rute yang dimulai dari satu titik awal, setiap kota harus dikunjungi sekali dan kemudian kembali ke tempat asal sehingga total jarak atau waktu perjalanan adalah minimum. Untuk mengatasi kedakpastian jarak atau waktu perjalanan, maka perlu dilakukan pengembangan model TSP. Salah satu bidang Optimisasi yang mampu menyelesaikan permasalahan terkait ketidakpastian adalah Optimisasi Robust. Dalam makalah ini dibahas mengenai penerapan Optimisasi Robust pada TSP (RTSP menggunakan pendekatan Box Uncertainty dan diselesaikan dengan menggunakan Metode Branch and Bound. Disajikan simulasi numerik pada software aplikasi Maple untuk beberapa kasus nyata terkait penerapan Optimisasi RTSP , seperti masalah manajemen konstruksi, penentuan jarak tempuh kota di Pulau Jawa, dan Penentuan Rute Mandiri Fun Run.

  14. An improved self-adaptive ant colony algorithm based on genetic strategy for the traveling salesman problem

    Science.gov (United States)

    Wang, Pan; Zhang, Yi; Yan, Dong

    2018-05-01

    Ant Colony Algorithm (ACA) is a powerful and effective algorithm for solving the combination optimization problem. Moreover, it was successfully used in traveling salesman problem (TSP). But it is easy to prematurely converge to the non-global optimal solution and the calculation time is too long. To overcome those shortcomings, a new method is presented-An improved self-adaptive Ant Colony Algorithm based on genetic strategy. The proposed method adopts adaptive strategy to adjust the parameters dynamically. And new crossover operation and inversion operation in genetic strategy was used in this method. We also make an experiment using the well-known data in TSPLIB. The experiment results show that the performance of the proposed method is better than the basic Ant Colony Algorithm and some improved ACA in both the result and the convergence time. The numerical results obtained also show that the proposed optimization method can achieve results close to the theoretical best known solutions at present.

  15. The application of ant colony optimization in the solution of 3D traveling salesman problem on a sphere

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    Hüseyin Eldem

    2017-08-01

    Full Text Available Traveling Salesman Problem (TSP is a problem in combinatorial optimization that should be solved by a salesperson who has to travel all cities at the minimum cost (minimum route and return to the starting city (node. Todays, to resolve the minimum cost of this problem, many optimization algorithms have been used. The major ones are these metaheuristic algorithms. In this study, one of the metaheuristic methods, Ant Colony Optimization (ACO method (Max-Min Ant System – MMAS, was used to solve the Non-Euclidean TSP, which consisted of sets of different count points coincidentally located on the surface of a sphere. In this study seven point sets were used which have different point count. The performance of the MMAS method solving Non-Euclidean TSP problem was demonstrated by different experiments. Also, the results produced by ACO are compared with Discrete Cuckoo Search Algorithm (DCS and Genetic Algorithm (GA that are in the literature. The experiments for TSP on a sphere, show that ACO’s average results were better than the GA’s average results and also best results of ACO successful than the DCS.

  16. Multi-Objective Ant Colony Optimization Based on the Physarum-Inspired Mathematical Model for Bi-Objective Traveling Salesman Problems.

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    Zili Zhang

    Full Text Available Bi-objective Traveling Salesman Problem (bTSP is an important field in the operations research, its solutions can be widely applied in the real world. Many researches of Multi-objective Ant Colony Optimization (MOACOs have been proposed to solve bTSPs. However, most of MOACOs suffer premature convergence. This paper proposes an optimization strategy for MOACOs by optimizing the initialization of pheromone matrix with the prior knowledge of Physarum-inspired Mathematical Model (PMM. PMM can find the shortest route between two nodes based on the positive feedback mechanism. The optimized algorithms, named as iPM-MOACOs, can enhance the pheromone in the short paths and promote the search ability of ants. A series of experiments are conducted and experimental results show that the proposed strategy can achieve a better compromise solution than the original MOACOs for solving bTSPs.

  17. Traveling salesman problems with PageRank Distance on complex networks reveal community structure

    Science.gov (United States)

    Jiang, Zhongzhou; Liu, Jing; Wang, Shuai

    2016-12-01

    In this paper, we propose a new algorithm for community detection problems (CDPs) based on traveling salesman problems (TSPs), labeled as TSP-CDA. Since TSPs need to find a tour with minimum cost, cities close to each other are usually clustered in the tour. This inspired us to model CDPs as TSPs by taking each vertex as a city. Then, in the final tour, the vertices in the same community tend to cluster together, and the community structure can be obtained by cutting the tour into a couple of paths. There are two challenges. The first is to define a suitable distance between each pair of vertices which can reflect the probability that they belong to the same community. The second is to design a suitable strategy to cut the final tour into paths which can form communities. In TSP-CDA, we deal with these two challenges by defining a PageRank Distance and an automatic threshold-based cutting strategy. The PageRank Distance is designed with the intrinsic properties of CDPs in mind, and can be calculated efficiently. In the experiments, benchmark networks with 1000-10,000 nodes and varying structures are used to test the performance of TSP-CDA. A comparison is also made between TSP-CDA and two well-established community detection algorithms. The results show that TSP-CDA can find accurate community structure efficiently and outperforms the two existing algorithms.

  18. Genetic algorithm based on virus theory of evolution for traveling salesman problem; Virus shinkaron ni motozuku identeki algorithm no junkai salesman mondai eno oyo

    Energy Technology Data Exchange (ETDEWEB)

    Kubota, N. [Osaka Inst. of Technology, Osaka (Japan); Fukuda, T. [Nagoya University, Nagoya (Japan)

    1998-05-31

    This paper deals with virus evolutionary genetic algorithm. The genetic algorithms (GAs) have been demonstrated its effectiveness in optimization problems in these days. In general, the GAs simulate the survival of fittest by natural selection and the heredity of the Darwin`s theory of evolution. However, some types of evolutionary hypotheses such as neutral theory of molecular evolution, Imanishi`s evolutionary theory, serial symbiosis theory, and virus theory of evolution, have been proposed in addition to the Darwinism. Virus theory of evolution is based on the view that the virus transduction is a key mechanism for transporting segments of DNA across species. This paper proposes genetic algorithm based on the virus theory of evolution (VE-GA), which has two types of populations: host population and virus population. The VE-GA is composed of genetic operators and virus operators such as reverse transcription and incorporation. The reverse transcription operator transcribes virus genes on the chromosome of host individual and the incorporation operator creates new genotype of virus from host individual. These operators by virus population make it possible to transmit segment of DNA between individuals in the host population. Therefore, the VE-GA realizes not only vertical but also horizontal propagation of genetic information. Further, the VE-GA is applied to the traveling salesman problem in order to show the effectiveness. 20 refs., 10 figs., 3 tabs.

  19. Automatic Combination of Operators in a Genetic Algorithm to Solve the Traveling Salesman Problem.

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    Carlos Contreras-Bolton

    Full Text Available Genetic algorithms are powerful search methods inspired by Darwinian evolution. To date, they have been applied to the solution of many optimization problems because of the easy use of their properties and their robustness in finding good solutions to difficult problems. The good operation of genetic algorithms is due in part to its two main variation operators, namely, crossover and mutation operators. Typically, in the literature, we find the use of a single crossover and mutation operator. However, there are studies that have shown that using multi-operators produces synergy and that the operators are mutually complementary. Using multi-operators is not a simple task because which operators to use and how to combine them must be determined, which in itself is an optimization problem. In this paper, it is proposed that the task of exploring the different combinations of the crossover and mutation operators can be carried out by evolutionary computing. The crossover and mutation operators used are those typically used for solving the traveling salesman problem. The process of searching for good combinations was effective, yielding appropriate and synergic combinations of the crossover and mutation operators. The numerical results show that the use of the combination of operators obtained by evolutionary computing is better than the use of a single operator and the use of multi-operators combined in the standard way. The results were also better than those of the last operators reported in the literature.

  20. Optimal solution for travelling salesman problem using heuristic shortest path algorithm with imprecise arc length

    Science.gov (United States)

    Bakar, Sumarni Abu; Ibrahim, Milbah

    2017-08-01

    The shortest path problem is a popular problem in graph theory. It is about finding a path with minimum length between a specified pair of vertices. In any network the weight of each edge is usually represented in a form of crisp real number and subsequently the weight is used in the calculation of shortest path problem using deterministic algorithms. However, due to failure, uncertainty is always encountered in practice whereby the weight of edge of the network is uncertain and imprecise. In this paper, a modified algorithm which utilized heuristic shortest path method and fuzzy approach is proposed for solving a network with imprecise arc length. Here, interval number and triangular fuzzy number in representing arc length of the network are considered. The modified algorithm is then applied to a specific example of the Travelling Salesman Problem (TSP). Total shortest distance obtained from this algorithm is then compared with the total distance obtained from traditional nearest neighbour heuristic algorithm. The result shows that the modified algorithm can provide not only on the sequence of visited cities which shown to be similar with traditional approach but it also provides a good measurement of total shortest distance which is lesser as compared to the total shortest distance calculated using traditional approach. Hence, this research could contribute to the enrichment of methods used in solving TSP.

  1. On the Optimization and Parallelizing Little Algorithm for Solving the Traveling Salesman Problem

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    V. V. Vasilchikov

    2016-01-01

    Full Text Available The paper describes some ways to accelerate solving the NP-complete Traveling Salesman Problem. The classic Little algorithm belonging to the category of ”branch and bound methods” can solve it both for directed and undirected graphs. However, for undirected graphs its operation can be accelerated by eliminating the consideration of branches examined earlier. The paper proposes changes to be made in the key operations of the algorithm to speed up its execution. It also describes the results of an experiment that demonstrated a significant acceleration of solving the problem by using an advanced algorithm. Another way to speed up the work is to parallelize the algorithm. For problems of this kind it is difficult to break the task into a sufficient number of subtasks having comparable complexity. Their parallelism arises dynamically during the execution. For such problems, it seems reasonable to use parallel-recursive algorithms. In our case the use of the library RPM ParLib developed by the author was a good choice. It allows us to develop effective applications for parallel computing on a local network using any .NET-compatible programming language. We used C# to develop the programs. Parallel applications were developed as for basic and modified algorithms, the comparing of their speed was made. Experiments were performed for the graphs with the number of vertexes up to 45 and with the number of network computers up to 16. We also investigated the acceleration that can be achieved by parallelizing the basic Little algorithm for directed graphs. The results of these experiments are also presented in the paper. 

  2. Computational Recognition of RNA Splice Sites by Exact Algorithms for the Quadratic Traveling Salesman Problem

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    Anja Fischer

    2015-06-01

    Full Text Available One fundamental problem of bioinformatics is the computational recognition of DNA and RNA binding sites. Given a set of short DNA or RNA sequences of equal length such as transcription factor binding sites or RNA splice sites, the task is to learn a pattern from this set that allows the recognition of similar sites in another set of DNA or RNA sequences. Permuted Markov (PM models and permuted variable length Markov (PVLM models are two powerful models for this task, but the problem of finding an optimal PM model or PVLM model is NP-hard. While the problem of finding an optimal PM model or PVLM model of order one is equivalent to the traveling salesman problem (TSP, the problem of finding an optimal PM model or PVLM model of order two is equivalent to the quadratic TSP (QTSP. Several exact algorithms exist for solving the QTSP, but it is unclear if these algorithms are capable of solving QTSP instances resulting from RNA splice sites of at least 150 base pairs in a reasonable time frame. Here, we investigate the performance of three exact algorithms for solving the QTSP for ten datasets of splice acceptor sites and splice donor sites of five different species and find that one of these algorithms is capable of solving QTSP instances of up to 200 base pairs with a running time of less than two days.

  3. Improvement of algorithm using Kohonen`s self-organizing feature map for the traveling salesman problem; Kohonen jiko soshikika tokucho mappu wo mochiita ukai serusuman mondai kaiho no kairyo

    Energy Technology Data Exchange (ETDEWEB)

    Fujimura, K.; Tokutaka, H.; Tanaka, H.; Kishida, S. [Tottori Univ., Tottori (Japan); Oshima, Y. [Mita Industrial Co. Ltd., Osaka (Japan)

    1996-02-20

    Traveling salesman problem (TSP) is one of the combinatorial optimization problems. The solution of this problem is to seek the way of how to visit every city only once within the shortest traveling distance. The solutions of this problem are studied a lot hitherto since they are the index for observing the basic properties of optimization algorithm. The method of Angeniol using the elf-organizing feature map is greatly forceful from the viewpoint of its short calculating time. In this study, regarding the algorithm of Angeniol, the conditions of obtaining the shortest tour length within shorter time are examined. Namely, a half of calculating time is reduced by changing Angeniol method into the method of making the node create after the searches of M cities. Additionally, the calculating time for unchanged tour length is reduced to one fourth by adding an inertia item in accordance with the variation of the number of total nodes. 14 refs., 8 figs.

  4. ON THE USE OF LYTLE’S ALGORITHM FOR SOLVING TRAVELING SALESMAN PROBLEM AT DEVELOPING SUBURBAN ROUTE

    Directory of Open Access Journals (Sweden)

    S. Kantsedal

    2012-01-01

    Full Text Available Lytle’s algorithm is described as proposed for an accurate solution of the salesman Problem. Statistical characteristics of solution duration with lytle’s algorithm of some problems and of their modifications are specified. On the basis of the results obtained the limits for the algorithm practical specification in the preparation of the route network are given.

  5. Deterministic algorithms for multi-criteria Max-TSP

    NARCIS (Netherlands)

    Manthey, Bodo

    2012-01-01

    We present deterministic approximation algorithms for the multi-criteria maximum traveling salesman problem (Max-TSP). Our algorithms are faster and simpler than the existing randomized algorithms. We devise algorithms for the symmetric and asymmetric multi-criteria Max-TSP that achieve ratios of

  6. Application of supernetworks in modeling activity-travel behaviour

    NARCIS (Netherlands)

    Liao, F.; Arentze, T.A.; Timmermans, H.J.P.

    2011-01-01

    Network representation and optimization has for long been applied to address vast engineering and scientific problems. Examples are originated from the Seven Bridges of Konigsberg, to a variety of classic P and NP-hard problems such minimum spanning tree, shortest path, and traveling salesman

  7. Reachability cuts for the vehicle routing problem with time windows

    DEFF Research Database (Denmark)

    Lysgaard, Jens

    2004-01-01

    This paper introduces a class of cuts, called reachability cuts, for the Vehicle Routing Problem with Time Windows (VRPTW). Reachability cuts are closely related to cuts derived from precedence constraints in the Asymmetric Traveling Salesman Problem with Time Windows and to k-path cuts...

  8. The Application of Fitness Sharing Method in Evolutionary Algorithm to Optimizing the Travelling Salesman Problem (TSP

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    Nurmaulidar Nurmaulidar

    2015-04-01

    Full Text Available Travelling Salesman Problem (TSP is one of complex optimization problem that is difficult to be solved, and require quite a long time for a large number of cities. Evolutionary algorithm is a precise algorithm used in solving complex optimization problem as it is part of heuristic method. Evolutionary algorithm, like many other algorithms, also experiences a premature convergence phenomenon, whereby variation is eliminated from a population of fairly fit individuals before a complete solution is achieved. Therefore it requires a method to delay the convergence. A specific method of fitness sharing called phenotype fitness sharing has been used in this research. The aim of this research is to find out whether fitness sharing in evolutionary algorithm is able to optimize TSP. There are two concepts of evolutionary algorithm being used in this research. the first one used single elitism and the other one used federated solution. The two concepts had been tested to the method of fitness sharing by using the threshold of 0.25, 0.50 and 0.75. The result was then compared to a non fitness sharing method. The result in this study indicated that by using single elitism concept, fitness sharing was able to give a more optimum result for the data of 100-1000 cities. On the other hand, by using federation solution concept, fitness sharing can yield a more optimum result for the data above 1000 cities, as well as a better solution of data-spreading compared to the method without fitness sharing.

  9. Tolerance based algorithms for the ATSP

    NARCIS (Netherlands)

    Goldengorin, B; Sierksma, G; Turkensteen, M; Hromkovic, J; Nagl, M; Westfechtel, B

    2004-01-01

    In this paper we use arc tolerances, instead of arc costs, to improve Branch-and-Bound type algorithms for the Asymmetric Traveling Salesman Problem (ATSP). We derive new tighter lower bounds based on exact and approximate bottleneck upper tolerance values of the Assignment Problem (AP). It is shown

  10. Path inequalities for the vehicle routing problem with time windows

    DEFF Research Database (Denmark)

    Kallehauge, Brian; Boland, Natashia; Madsen, Oli B.G.

    2007-01-01

    In this paper we introduce a new formulation of the vehicle routing problem with time windows (VRPTW) involving only binary variables. The new formulation is based on the formulation of the asymmetric traveling salesman problem with time windows by Ascheuer et al. (Networks 36 (2000) 69-79) and has...

  11. TSP tour domination and Hamilton cycle decompositions of regular digraphs

    DEFF Research Database (Denmark)

    Gutin, Gregory; Yeo, Anders

    2001-01-01

    by the relative performance compared to the optimal value. In particular, we show that for the asymmetric traveling salesman problem, there is a deterministic polynomial time algorithm that finds a tour that is at least as good as the median of all tour values. Our algorithm uses an unpublished theorem...

  12. Metaheurísticas híbridas para resolução do problema do caixeiro viajante com coleta de prêmios Hybrid metaheuristics for solve the prize collecting traveling salesman problem

    Directory of Open Access Journals (Sweden)

    Antonio Augusto Chaves

    2007-08-01

    Full Text Available O Problema do Caixeiro Viajante com Coleta de Prêmios (PCVCP pode ser associado a um caixeiro que coleta um prêmio em cada cidade visitada e paga uma penalidade para cada cidade não visitada, com um custo de deslocamento entre as cidades. O problema encontra-se em minimizar o somatório dos custos da viagem e penalidades, enquanto inclui na sua rota um número suficiente de cidades que lhe permita coletar um prêmio mínimo preestabelecido. Este trabalho contribui com o desenvolvimento de metaheurísticas híbridas para o PCVCP, baseadas em GRASP e métodos de busca em vizinhança variável (VNS/VND para solucionar aproximadamente o PCVCP. De forma a validar as soluções obtidas, propõe-se uma formulação matemática a ser resolvida por um solver comercial, objetivando encontrar a solução ótima para o problema, sendo este solver aplicado a problemas de pequeno porte. Resultados computacionais demonstram a eficiência da abordagem híbrida proposta, tanto em relação à qualidade da solução final obtida quanto em relação ao tempo de execução.The Prize Collecting Traveling Salesman Problem (PCTSP can be associated to a salesman who collects a prize in each city visited and pays a penalty for each city not visited, with travel costs among the cities. The objective is to minimize the sum of the travel costs and penalties, including in the tour enough number of cities that allow collecting a minimum prize. This paper contributes with the development of a hybrid metaheuristic to PCTSP, based on GRASP and search methods in variable neighborhood (VNS/VND to solve PCTSP approximately. In order to validate the obtained solutions, we proposed a mathematical formulation to be solved by a commercial solver to find the best solution to the problem, being this solver applied to small problems. Computational results demonstrate the efficiency of the proposed method, as much in relation to the quality of the obtained final solution as in relation

  13. PENYELESAIAN MULTI TRAVELING SALESMAN PROBLEM DENGAN ALGORITMA GENETIKA

    Directory of Open Access Journals (Sweden)

    NI KADEK MAYULIANA

    2017-01-01

    Full Text Available Genetic algorithm is a part of heuristic algorithm which can be applied to solve various computational problems. This work is directed to study the performance of the genetic algorithm (GA to solve Multi Traveling Salesmen Problem (multi-TSP. GA is simulated to determine the shortest route for 5 to 10 salesmen who travelled 10 to 30 cities. The performance of this algorithm is studied based on the minimum distance and the processing time required for 10 repetitions for each of cities-salesmen combination. The result showed that the minimum distance and the processing time of the GA increase consistently whenever the number of cities to visit increase. In addition, different number of sales who visited certain number of cities proved significantly affect the running time of GA, but did not prove significantly affect the minimum distance.

  14. The modification of hybrid method of ant colony optimization, particle swarm optimization and 3-OPT algorithm in traveling salesman problem

    Science.gov (United States)

    Hertono, G. F.; Ubadah; Handari, B. D.

    2018-03-01

    The traveling salesman problem (TSP) is a famous problem in finding the shortest tour to visit every vertex exactly once, except the first vertex, given a set of vertices. This paper discusses three modification methods to solve TSP by combining Ant Colony Optimization (ACO), Particle Swarm Optimization (PSO) and 3-Opt Algorithm. The ACO is used to find the solution of TSP, in which the PSO is implemented to find the best value of parameters α and β that are used in ACO.In order to reduce the total of tour length from the feasible solution obtained by ACO, then the 3-Opt will be used. In the first modification, the 3-Opt is used to reduce the total tour length from the feasible solutions obtained at each iteration, meanwhile, as the second modification, 3-Opt is used to reduce the total tour length from the entire solution obtained at every iteration. In the third modification, 3-Opt is used to reduce the total tour length from different solutions obtained at each iteration. Results are tested using 6 benchmark problems taken from TSPLIB by calculating the relative error to the best known solution as well as the running time. Among those modifications, only the second and third modification give satisfactory results except the second one needs more execution time compare to the third modifications.

  15. The A-priori Traveling Salesman Problem with Time Windows

    DEFF Research Database (Denmark)

    Larsen, Allan; Madsen, Oli B.G.; Solomon, Marius M.

    2004-01-01

    seek to minimize lateness and examine the impact of this criterion choice on the distance traveled. Our focus on lateness is motivated by the problem faced by overnight mail service providers. We propose a real-time solution method that requires the vehicle, when idle, to wait at the current customer......In this paper we examine the traveling saleman problem with time windows for various degrees of dynamism. In contrast to the static problem, where the dispatcher can plan ahead, in the dynamic version, part or all of the necessary information becomes available only during the day of operation. We...... randomly generated data and on a real-world case study indicate that all policies proved capable of significantly reducing lateness. Our results also show that this can be accomplished with only small distance increases. The basic policy outperformed the other methods primarily when lateness and distance...

  16. On the Core of Routing Games with Revenues

    NARCIS (Netherlands)

    A. Estévez-Fernandéz (Arantza); P. Borm; M. Meertens; H. Reijnierse

    2006-01-01

    htmlabstract Traveling salesman problems with revenues form a generalization of traveling salesman problems. Here, next to travel costs an explicit revenue is generated by visiting a city. We analyze routing problems with revenues, where a predetermined route on all cities determines the tours

  17. On the Core of Routing Games with Revenues

    NARCIS (Netherlands)

    Estevez Fernandez, M.A.; Borm, P.E.M.; Meertens, M.; Reijnierse, J.H.

    2006-01-01

    Traveling salesman problems with revenues form a generalization of traveling salesman problems.Here, next to travel costs an explicit revenue is generated by visiting a city.We analyze routing problems with revenues, where a predetermined route on all cities determines the tours along

  18. Heuristics methods for the flow shop scheduling problem with separated setup times

    Directory of Open Access Journals (Sweden)

    Marcelo Seido Nagano

    2012-06-01

    Full Text Available This paper deals with the permutation flow shop scheduling problem with separated machine setup times. As a result of an investigation on the problem characteristics, four heuristics methods are proposed with procedures of the construction sequencing solution by an analogy with the asymmetric traveling salesman problem with the objective of minimizing makespan. Experimental results show that one of the new heuristics methods proposed provide high quality solutions in comparisons with the evaluated methods considered in the literature.

  19. On the core of routing games with revenues

    NARCIS (Netherlands)

    Estevez Fernandez, M.A.; Borm, P.; Meertens, M.; Reijnierse, H.

    2009-01-01

    Traveling salesman problems with revenues form a generalization of traveling salesman problems. Here, next to travel costs an explicit revenue is generated by visiting a city. We analyze routing problems with revenues, where a predetermined route on all cities determines the tours along subgroups.

  20. Arthur Miller's Death of a Salesman

    OpenAIRE

    Apolinário, Valdemar dos Passos

    2001-01-01

    Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão. Programa de Pós-Graduação em Letras/Inglês e Literatura Correspondente Investiga como as questões político-sociais atingiram as personagens de Arthur Miller na peça Death of a Salesman, contribuindo para moldar suas personalidades e determinando o seu destino. Mostra que, para Arthur Miller, Benjamin Franklin foi a principal fonte de inspiração no seu retrato das preocupações políticas, da c...

  1. Aplicación de un algoritmo ACO al problema de taller de flujo de permutación con tiempos de preparación dependientes de la secuencia y minimización de makespan An ant colony algorithm for the permutation flowshop with sequence dependent setup times and makespan minimization

    Directory of Open Access Journals (Sweden)

    Eduardo Salazar Hornig

    2011-08-01

    Full Text Available En este trabajo se estudió el problema de secuenciamiento de trabajos en el taller de flujo de permutación con tiempos de preparación dependientes de la secuencia y minimización de makespan. Para ello se propuso un algoritmo de optimización mediante colonia de hormigas (ACO, llevando el problema original a una estructura semejante al problema del vendedor viajero TSP (Traveling Salesman Problem asimétrico, utilizado para su evaluación problemas propuestos en la literatura y se compara con una adaptación de la heurística NEH (Nawaz-Enscore-Ham. Posteriormente se aplica una búsqueda en vecindad a la solución obtenida tanto por ACO como NEH.This paper studied the permutation flowshop with sequence dependent setup times and makespan minimization. An ant colony algorithm which turns the original problem into an asymmetric TSP (Traveling Salesman Problem structure is presented, and applied to problems proposed in the literature and is compared with an adaptation of the NEH heuristic. Subsequently a neighborhood search was applied to the solution obtained by the ACO algorithm and the NEH heuristic.

  2. An Adaptive Evolutionary Algorithm for Traveling Salesman Problem with Precedence Constraints

    Directory of Open Access Journals (Sweden)

    Jinmo Sung

    2014-01-01

    Full Text Available Traveling sales man problem with precedence constraints is one of the most notorious problems in terms of the efficiency of its solution approach, even though it has very wide range of industrial applications. We propose a new evolutionary algorithm to efficiently obtain good solutions by improving the search process. Our genetic operators guarantee the feasibility of solutions over the generations of population, which significantly improves the computational efficiency even when it is combined with our flexible adaptive searching strategy. The efficiency of the algorithm is investigated by computational experiments.

  3. A Cost Assessment of the Dayton Public Schools Vehicle Routing Problem

    Science.gov (United States)

    2009-03-01

    known problems: the Traveling Salesman Problem (TSP) and the Bin Packing Problem ( BPP ) (Ralphs, 2003). The VRP has a plethora of real world...well known problems: the Traveling Salesman Problem (TSP) and the Bin Packing Problem ( BPP ) (Ralphs, 2003). The VRP has a plethora of real world

  4. An Investigation of Starting Point Preferences in Human Performance on Traveling Salesman Problems

    Science.gov (United States)

    MacGregor, James N.

    2014-01-01

    Previous studies have shown that people start traveling sales problem tours significantly more often from boundary than from interior nodes. There are a number of possible reasons for such a tendency: first, it may arise as a direct result of the processes involved in tour construction; second, boundary points may be perceptually more salient than…

  5. Focusing on the Golden Ball Metaheuristic: An Extended Study on a Wider Set of Problems

    Directory of Open Access Journals (Sweden)

    E. Osaba

    2014-01-01

    Full Text Available Nowadays, the development of new metaheuristics for solving optimization problems is a topic of interest in the scientific community. In the literature, a large number of techniques of this kind can be found. Anyway, there are many recently proposed techniques, such as the artificial bee colony and imperialist competitive algorithm. This paper is focused on one recently published technique, the one called Golden Ball (GB. The GB is a multiple-population metaheuristic based on soccer concepts. Although it was designed to solve combinatorial optimization problems, until now, it has only been tested with two simple routing problems: the traveling salesman problem and the capacitated vehicle routing problem. In this paper, the GB is applied to four different combinatorial optimization problems. Two of them are routing problems, which are more complex than the previously used ones: the asymmetric traveling salesman problem and the vehicle routing problem with backhauls. Additionally, one constraint satisfaction problem (the n-queen problem and one combinatorial design problem (the one-dimensional bin packing problem have also been used. The outcomes obtained by GB are compared with the ones got by two different genetic algorithms and two distributed genetic algorithms. Additionally, two statistical tests are conducted to compare these results.

  6. Focusing on the Golden Ball Metaheuristic: An Extended Study on a Wider Set of Problems

    Science.gov (United States)

    Osaba, E.; Diaz, F.; Carballedo, R.; Onieva, E.; Perallos, A.

    2014-01-01

    Nowadays, the development of new metaheuristics for solving optimization problems is a topic of interest in the scientific community. In the literature, a large number of techniques of this kind can be found. Anyway, there are many recently proposed techniques, such as the artificial bee colony and imperialist competitive algorithm. This paper is focused on one recently published technique, the one called Golden Ball (GB). The GB is a multiple-population metaheuristic based on soccer concepts. Although it was designed to solve combinatorial optimization problems, until now, it has only been tested with two simple routing problems: the traveling salesman problem and the capacitated vehicle routing problem. In this paper, the GB is applied to four different combinatorial optimization problems. Two of them are routing problems, which are more complex than the previously used ones: the asymmetric traveling salesman problem and the vehicle routing problem with backhauls. Additionally, one constraint satisfaction problem (the n-queen problem) and one combinatorial design problem (the one-dimensional bin packing problem) have also been used. The outcomes obtained by GB are compared with the ones got by two different genetic algorithms and two distributed genetic algorithms. Additionally, two statistical tests are conducted to compare these results. PMID:25165742

  7. Theoretical analysis of two ACO approaches for the traveling salesman problem

    DEFF Research Database (Denmark)

    Kötzing, Timo; Neumann, Frank; Röglin, Heiko

    2012-01-01

    Bioinspired algorithms, such as evolutionary algorithms and ant colony optimization, are widely used for different combinatorial optimization problems. These algorithms rely heavily on the use of randomness and are hard to understand from a theoretical point of view. This paper contributes...... to the theoretical analysis of ant colony optimization and studies this type of algorithm on one of the most prominent combinatorial optimization problems, namely the traveling salesperson problem (TSP). We present a new construction graph and show that it has a stronger local property than one commonly used...... for constructing solutions of the TSP. The rigorous runtime analysis for two ant colony optimization algorithms, based on these two construction procedures, shows that they lead to good approximation in expected polynomial time on random instances. Furthermore, we point out in which situations our algorithms get...

  8. Heuristic Solution Approaches to the Double TSP with Multiple Stacks

    DEFF Research Database (Denmark)

    Petersen, Hanne Løhmann

    This paper introduces the Double Travelling Salesman Problem with Multiple Stacks and presents a three different metaheuristic approaches to its solution. The Double Travelling Salesman Problem with Multiple Stacks is concerned with finding the shortest route performing pickups and deliveries in ...... are developed for the problem and used with each of the heuristics. Finally some computational results are given along with lower bounds on the objective value....

  9. Heuristic Solution Approaches to the Double TSP with Multiple Stacks

    DEFF Research Database (Denmark)

    Petersen, Hanne Løhmann

    2006-01-01

    This paper introduces the Double Travelling Salesman Problem with Multiple Stacks and presents a three different metaheuristic approaches to its solution. The Double Travelling Salesman Problem with Multiple Stacks is concerned with finding the shortest route performing pickups and deliveries in ...... are developed for the problem and used with each of the heuristics. Finally some computational results are given along with lower bounds on the objective value....

  10. Motion Planning and Task Assignment for Unmanned Aerial Vehicles Cooperating with Unattended Ground Sensors

    Science.gov (United States)

    2014-10-24

    constraints on its motion. This problem was formalized as the Dubins travelling salesman problem (TSP). In the second phase of the research we have...given constraints on its motion. This problem was formalized as the Dubins travelling salesman problem (TSP). The contributions of the study in the...assumptions were made on the magnitude of the intercity distances. The two algorithms complement each other in terms of their range of applicability

  11. Certification of an optimal TSP tour through 85,900 cities

    DEFF Research Database (Denmark)

    Applegate, David L.; Bixby, Robert E.; Chvatal, Vasek

    2009-01-01

    We describe a computer code and data that together certify the optimality of a solution to the 85,900-city traveling salesman problem pla85900, the largest instance in the TSPLIB collection of challenge problems......We describe a computer code and data that together certify the optimality of a solution to the 85,900-city traveling salesman problem pla85900, the largest instance in the TSPLIB collection of challenge problems...

  12. Advances in bio-inspired computing for combinatorial optimization problems

    CERN Document Server

    Pintea, Camelia-Mihaela

    2013-01-01

    Advances in Bio-inspired Combinatorial Optimization Problems' illustrates several recent bio-inspired efficient algorithms for solving NP-hard problems.Theoretical bio-inspired concepts and models, in particular for agents, ants and virtual robots are described. Large-scale optimization problems, for example: the Generalized Traveling Salesman Problem and the Railway Traveling Salesman Problem, are solved and their results are discussed.Some of the main concepts and models described in this book are: inner rule to guide ant search - a recent model in ant optimization, heterogeneous sensitive a

  13. An Adaptive Clustering Approach Based on Minimum Travel Route Planning for Wireless Sensor Networks with a Mobile Sink.

    Science.gov (United States)

    Tang, Jiqiang; Yang, Wu; Zhu, Lingyun; Wang, Dong; Feng, Xin

    2017-04-26

    In recent years, Wireless Sensor Networks with a Mobile Sink (WSN-MS) have been an active research topic due to the widespread use of mobile devices. However, how to get the balance between data delivery latency and energy consumption becomes a key issue of WSN-MS. In this paper, we study the clustering approach by jointly considering the Route planning for mobile sink and Clustering Problem (RCP) for static sensor nodes. We solve the RCP problem by using the minimum travel route clustering approach, which applies the minimum travel route of the mobile sink to guide the clustering process. We formulate the RCP problem as an Integer Non-Linear Programming (INLP) problem to shorten the travel route of the mobile sink under three constraints: the communication hops constraint, the travel route constraint and the loop avoidance constraint. We then propose an Imprecise Induction Algorithm (IIA) based on the property that the solution with a small hop count is more feasible than that with a large hop count. The IIA algorithm includes three processes: initializing travel route planning with a Traveling Salesman Problem (TSP) algorithm, transforming the cluster head to a cluster member and transforming the cluster member to a cluster head. Extensive experimental results show that the IIA algorithm could automatically adjust cluster heads according to the maximum hops parameter and plan a shorter travel route for the mobile sink. Compared with the Shortest Path Tree-based Data-Gathering Algorithm (SPT-DGA), the IIA algorithm has the characteristics of shorter route length, smaller cluster head count and faster convergence rate.

  14. Improving the efficiency of spatially selective operations for agricultural robotics in cropping field

    Directory of Open Access Journals (Sweden)

    Y. L. Li

    2013-01-01

    Full Text Available Cropping fields often have well-defined poor-performing patches due to spatial and temporal variability. In an attempt to increase crop performance on poor patches, spatially selective field operations may be performed by agricultural robotics to apply additional inputs with targeted requirements. This paper addresses the route planning problem for an agricultural robot that has to treat some poor-patches in a field with row crops, with respect to the minimization of the total non-working distance travelled during headland turnings and in-field travel distance. The traversal of patches in the field is expressed as the traversal of a mixed weighted graph, and then the problem of finding an optimal patch sequence is formulated as an asymmetric traveling salesman problem and solved by the partheno-genetic algorithm. The proposed method is applied on a cropping field located in Northwestern China. Research results show that by using optimum patch sequences, the total non-working distance travelled during headland turnings and in-field travel distance can be reduced. But the savings on the non-working distance inside the field interior depend on the size and location of patches in the field, and the introduction of agricultural robotics is beneficial to increase field efficiency.

  15. Improving the efficiency of spatially selective operations for agricultural robotics in cropping field

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y. L.; Yi, S. P.

    2013-05-01

    Cropping fields often have well-defined poor-performing patches due to spatial and temporal variability. In an attempt to increase crop performance on poor patches, spatially selective field operations may be performed by agricultural robotics to apply additional inputs with targeted requirements. This paper addresses the route planning problem for an agricultural robot that has to treat some poor-patches in a field with row crops, with respect to the minimization of the total non-working distance travelled during headland turnings and in-field travel distance. The traversal of patches in the field is expressed as the traversal of a mixed weighted graph, and then the problem of finding an optimal patch sequence is formulated as an asymmetric traveling salesman problem and solved by the parthenogenetic algorithm. The proposed method is applied on a cropping field located in Northwestern China. Research results show that by using optimum patch sequences, the total non-working distance travelled during headland turnings and in-field travel distance can be reduced. But the savings on the non-working distance inside the field interior depend on the size and location of patches in the field, and the introduction of agricultural robotics is beneficial to increase field efficiency. (Author) 21 refs.

  16. [Viral hepatitis in travellers].

    Science.gov (United States)

    Abreu, Cândida

    2007-01-01

    Considering the geographical asymmetric distribution of viral hepatitis A, B and E, having a much higher prevalence in the less developed world, travellers from developed countries are exposed to a considerable and often underestimated risk of hepatitis infection. In fact a significant percentage of viral hepatitis occurring in developed countries is travel related. This results from globalization and increased mobility from tourism, international work, humanitarian and religious missions or other travel related activities. Several studies published in Europe and North America shown that more than 50% of reported cases of hepatitis A are travel related. On the other hand frequent outbreaks of hepatitis A and E in specific geographic areas raise the risk of infection in these restricted zones and that should be clearly identified. Selected aspects related with the distribution of hepatitis A, B and E are reviewed, particularly the situation in Portugal according to the published studies, as well as relevant clinical manifestations and differential diagnosis of viral hepatitis. Basic prevention rules considering enteric transmitted hepatitis (hepatitis A and hepatitis E) and parenteral transmitted (hepatitis B) are reviewed as well as hepatitis A and B immunoprophylaxis. Common clinical situations and daily practice "pre travel" advice issues are discussed according to WHO/CDC recommendations and the Portuguese National Vaccination Program. Implications from near future availability of a hepatitis E vaccine, a currently in phase 2 trial, are highlighted. Potential indications for travellers to endemic countries like India, Nepal and some regions of China, where up to 30% of sporadic cases of acute viral hepatitis are caused by hepatitis E virus, are considered. Continued epidemiological surveillance for viral hepatitis is essential to recognize and control possible outbreaks, but also to identify new viral hepatitis agents that may emerge as important global health

  17. OPTIMAL TOUR CONSTRUCTIONS FOR MULTIPLE MOBILE ROBOTS

    Directory of Open Access Journals (Sweden)

    AMIR A. SHAFIE

    2011-04-01

    Full Text Available The attempts to use mobile robots in a variety of environments are currently being limited by their navigational capability, thus a set of robots must be configured for one specific environment. The problem of navigating an environment is the fundamental problem in mobile robotic where various methods including exact and heuristic approaches have been proposed to solve the problem. This paper proposed a solution to the navigation problem via the use of multiple robots to explore the environment employing heuristic methods to navigate the environment using a variant of a Traveling Salesman Problem (TSP known as Multiple Traveling Salesman Problem (M-TSP.

  18. 26 CFR 31.3402(j)-1 - Remuneration other than in cash for service performed by retail commission salesman.

    Science.gov (United States)

    2010-04-01

    ... performed by retail commission salesman. 31.3402(j)-1 Section 31.3402(j)-1 Internal Revenue INTERNAL REVENUE... EMPLOYMENT TAXES AND COLLECTION OF INCOME TAX AT SOURCE Collection of Income Tax at Source § 31.3402(j)-1.... (2) Section 3402(j) and this section are not applicable with respect to wages paid to the employee...

  19. Solución al Problema de Secuenciación de Trabajos mediante el Problema del Agente Viajero

    Directory of Open Access Journals (Sweden)

    G.E. Anaya Fuentes

    2016-10-01

    Full Text Available Resumen: En este trabajo se estudia el Problema de Secuenciación de Trabajos codificado como un Problema de Agente Viajero y resuelto mediante Algoritmos Genéticos. Se propone un Algoritmo Genético en donde se comparan dos tipos de selección: por torneo y por ruleta. Se realizan diferentes pruebas para la solución del Problema del Agente Viajero con los dos tipos de selección bajo diferentes parámetros: número de individuos, número de iteraciones, probabilidad de cruce y probabilidad de mutación; a partir de estos se seleccionan los parámetros y el tipo de selección. Posteriormente se codifica al Problema de Secuenciación como un Problema del Agente Viajero. La propuesta se presenta mediante la aplicación a diferentes ejemplos del Problema de Secuenciación de Trabajos y la comparación con los resultados obtenidos en la literatura. Abstract: In this paper we proposed a solution to the Job-Shop Scheduling Problem using the Traveling Salesman Problem solved by Genetic Algorithms. We proposed a genetic algorithm where we compare two types of selection: tournament and roulette. Different tests are performed to solve the Traveling Salesman Problem with the two types of selection under different parameters: number of individuals, number of iterations, crossover probability and mutation probability. Then the best type of selection and the best parameters are used to solve the Job-Shop Scheduling Problem with Genetic Algorithms for the Traveling Salesman Problem. The proposal is presented solving different examples of Job Sequencing Problem and compare them with the results obtained in the literature. Palabras clave: algoritmos eficientes, sistemas industriales de producción, problemas de optimización, problema de agente viajero, Keywords: Efficient algorithms, industrial production systems, optimization problem, traveling salesman problem

  20. Optimization processing of the elementary surfaces of the composite body parts on machines such as «machining center»

    Directory of Open Access Journals (Sweden)

    Євген Іванович Іванов

    2015-11-01

    Full Text Available This article describes the processing optimization and minimizing the number of tool changes. Two versions for setting the processing scheme, according to the rules for processing scheme setting for the «processing center» machines were offered. In the first version, according to the classical technology processing of each hole is carried out over all the passes, providing for the required accuracy of sizes and shapes. In the second version the number of tool changes is minimized. This method consists of dividing all the holes into groups according to their diameters. All the holes of the same diameter are processed over one pass; then the tools are changed and the holes of some other diameter are processed and so on. Let us consider the optimization problem. The traveling salesman problem - is one of the most famous problems in the theory of combinatorics. The problem is as follows: a travelling salesman (hawker must find the most advantageous route coming out of a town and visiting all other towns from 2,3,…to...n just once in an unknown order and come back to the first town. The distances between all the towns are known. It is necessary to determine in what order the Salesman must visit the towns so that the route should be the shortest. There exists just one absolutely precise algorithm - sorting options. This option is the longest, so the most inefficient. There are also simpler methods to solve the traveling salesman problem: the branch and bound algorithm and ant colony method and method of genetic algorithms

  1. GEZGİN SATICI PROBLEMİNİ ÇÖZMEK İÇİN YENİ BİR HİBRİD SEZGİSEL ALGORİTMA

    Directory of Open Access Journals (Sweden)

    Gözde KIZILATEŞ

    2015-05-01

    Full Text Available The Traveling Salesman Problem (TS P is an important and well known combinatoriyal opti- mization problem. The goal of the problem is to find the shortest tour that visits each city in a given list exactly once and then returns to the starting city. Although the definition of the travelling salesman problem is easy, it belongs to NP-Hard class. In this paper, a new hybrid heurist ic algorithm based on Nearest Neighbour (NN and Greedy heur istic algorithms is proposed for s olving the TSP. This proposed hybrid heuristic algorithm is compared with NN and Greedy heuristi cs. The experimental results show that the proposed algorithm is efficient

  2. A United Framework for Solving Multiagent Task Assignment Problems

    National Research Council Canada - National Science Library

    Cousin, Kevin

    2007-01-01

    .... The CMTS descriptor represents a wide range of classical and modern problems, such as job shop scheduling, the traveling salesman problem, vehicle routing, and cooperative multi-object tracking...

  3. Ant Systems for a Dynamic TSP - Ants Caught in a Traffic Jam

    NARCIS (Netherlands)

    Eyckelhof, C.J.; Dorigo, M.; Caro Di, G.; Snoek, M.; Sampels, M.

    2002-01-01

    In this paper we present a new Ants System approach to a dynamic Travelling Salesman Problem. Here the travel times between the cities are subject to change. To handle this dynamism several ways of adapting the pheromone matrix both locally and globally are considered. We show that the strategy of

  4. Determination of optimal self-drive tourism route using the orienteering problem method

    Science.gov (United States)

    Hashim, Zakiah; Ismail, Wan Rosmanira; Ahmad, Norfaieqah

    2013-04-01

    This paper was conducted to determine the optimal travel routes for self-drive tourism based on the allocation of time and expense by maximizing the amount of attraction scores assigned to each city involved. Self-drive tourism represents a type of tourism where tourists hire or travel by their own vehicle. It only involves a tourist destination which can be linked with a network of roads. Normally, the traveling salesman problem (TSP) and multiple traveling salesman problems (MTSP) method were used in the minimization problem such as determination the shortest time or distance traveled. This paper involved an alternative approach for maximization method which is maximize the attraction scores and tested on tourism data for ten cities in Kedah. A set of priority scores are used to set the attraction score at each city. The classical approach of the orienteering problem was used to determine the optimal travel route. This approach is extended to the team orienteering problem and the two methods were compared. These two models have been solved by using LINGO12.0 software. The results indicate that the model involving the team orienteering problem provides a more appropriate solution compared to the orienteering problem model.

  5. Development of Traveling Wave Actuators Using Waveguides of Different Geometrical Forms

    Directory of Open Access Journals (Sweden)

    Ramutis Bansevicius

    2016-01-01

    Full Text Available The paper covers the research and development of piezoelectric traveling wave actuators using different types of the waveguides. The introduced piezoelectric actuators can be characterized by specific areas of application, different resolution, and torque. All presented actuators are ultrasonic resonant devices and they were developed to increase amplitudes of the traveling wave oscillations of the contact surface. Three different waveguides are introduced, that is, symmetrical, asymmetrical, and cone type waveguide. A piezoelectric ring with the sectioned electrodes is used to excite traveling wave oscillations for all actuators. Operating principle, electrode pattern, and excitation regimes of piezoelectric actuators are described. A numerical modelling of the actuators was performed to validate the operating principle and to calculate trajectories of the contact points motion. Prototype actuators were made and experimental study was performed. The results of numerical and experimental analysis are discussed.

  6. Algorithms for Collecting Data from Cooperating Sensor Motes using Unmanned Vehicles

    DEFF Research Database (Denmark)

    Sundar, Kaarthik; Sujit, PB; Rathinam, Sivakumar

    2015-01-01

    of communication costs involved in transmitting the data from the motes to the cluster-heads and the travel costs of the UV is a minimum. This problem is a generalization of a single Traveling Salesman Problem (TSP) and is NP-Hard. This article presents a rounding algorithm and heuristics to solve the problem...

  7. Browse Title Index

    African Journals Online (AJOL)

    Items 701 - 750 of 985 ... Vol 16 (2010), On Typical Elastic Problem of Green's Function For Rectangular ... of Transfer Function Models using Genetic Algorithms, Abstract ... the Traveling Salesman And the Nearest Neighbors Algorithms, Abstract.

  8. Decision Support for Planning of Multimodal Transportation with Multiple Objectives

    DEFF Research Database (Denmark)

    Petersen, Hanne Løhmann

    phase, and considers passenger inconvenience at transfers at the same time. The paper presents a mathematical model of the problem, and the implementation of a large neighbourhood search solution procedure. The problem is solved for a real-life based problem instance, containing eight bus lines......-known issues. They both originate in the world of multimodality, and deal with problems that arise as a consequence of the combined use of several modes. The thesis introduces the Double Travelling Salesman Problem with Multiple Stacks (DTSPMS), which is a problem that combines routing and last...... compare to solutions of the regular Travelling Salesman Problem. Next, two papers are presented, introducing respectively heuristic and exact solution procedures for the problem. The heuristic approach tests a variety of metaheuristic solution approaches, of which a large neighbourhood search obtains...

  9. Photo-induced travelling waves in condensed Langmuir monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Tabe, Y [Yokoyama Nano-Structured Liquid Crystal Project, ERATO, Japan Science and Technology Corporation, 5-9-9 Tokodai, Tsukuba, Ibaraki 300-2635, Japan (Japan); Yamamoto, T [Yokoyama Nano-Structured Liquid Crystal Project, ERATO, Japan Science and Technology Corporation, 5-9-9 Tokodai, Tsukuba, Ibaraki 300-2635, Japan (Japan); Yokoyama, H [Yokoyama Nano-Structured Liquid Crystal Project, ERATO, Japan Science and Technology Corporation, 5-9-9 Tokodai, Tsukuba, Ibaraki 300-2635, Japan (Japan)

    2003-06-01

    We report the detailed properties of photo-induced travelling waves in liquid crystalline Langmuir monolayers composed of azobenzene derivatives. When the monolayer, in which the constituent rodlike molecules are coherently tilted from the layer normal, is weakly illuminated to undergo the trans-cis photo-isomerization, spatio-temporal periodic oscillations of the molecular azimuth begin over the entire excited area and propagate as a two-dimensional orientational wave. The wave formation takes place only when the film is formed at an asymmetric interface with broken up-down symmetry and when the chromophores are continuously excited near the long-wavelength edge of absorption to induce repeated photo-isomerizations between the trans and cis forms. Under proper illumination conditions, Langmuir monolayers composed of a wide variety of azobenzene derivatives have been confirmed to exhibit similar travelling waves with velocity proportional to the excitation power irrespective of the degree of amphiphilicity. The dynamics can be qualitatively explained by the modified reaction-diffusion model proposed by Reigada, Sagues and Mikhailov.

  10. Cost allocation in distribution planning

    International Nuclear Information System (INIS)

    Engevall, S.

    1996-01-01

    This thesis concerns cost allocation problems in distribution planning. The cost allocation problems we study are illustrated using the distribution planning situation at the Logistics department of Norsk Hydro Olje AB. The planning situation is modeled as a Traveling Salesman Problem and a Vehicle Routing Problem with an inhomogeneous fleet. The cost allocation problems are the problems of how to divide the transportation costs among the customers served in each problem. The cost allocation problems are formulated as cooperative games, in characteristic function form, where the customers are defined to be the players. The games contain five and 21 players respectively. Game theoretical solution concepts such as the core, the nucleolus, the Shapley value and the τ-value are discussed. From the empirical results we can, among other things, conclude that the core of the Traveling Salesman Game is large, and that the core of the Vehicle Routing Game is empty. In the accounting of Norsk Hydro the cost per m 3 can be found for each tour. We conclude that for a certain definition of the characteristic function, a cost allocation according to this principle will not be included in the core of the Traveling Salesman Game. The models and methods presented in this thesis can be applied to transportation problems similar to that of Norsk Hydro, independent of the type of products that are delivered. 96 refs, 11 figs, 26 tabs

  11. Cost allocation in distribution planning

    Energy Technology Data Exchange (ETDEWEB)

    Engevall, S.

    1996-12-31

    This thesis concerns cost allocation problems in distribution planning. The cost allocation problems we study are illustrated using the distribution planning situation at the Logistics department of Norsk Hydro Olje AB. The planning situation is modeled as a Traveling Salesman Problem and a Vehicle Routing Problem with an inhomogeneous fleet. The cost allocation problems are the problems of how to divide the transportation costs among the customers served in each problem. The cost allocation problems are formulated as cooperative games, in characteristic function form, where the customers are defined to be the players. The games contain five and 21 players respectively. Game theoretical solution concepts such as the core, the nucleolus, the Shapley value and the {tau}-value are discussed. From the empirical results we can, among other things, conclude that the core of the Traveling Salesman Game is large, and that the core of the Vehicle Routing Game is empty. In the accounting of Norsk Hydro the cost per m{sup 3} can be found for each tour. We conclude that for a certain definition of the characteristic function, a cost allocation according to this principle will not be included in the core of the Traveling Salesman Game. The models and methods presented in this thesis can be applied to transportation problems similar to that of Norsk Hydro, independent of the type of products that are delivered. 96 refs, 11 figs, 26 tabs

  12. Cost allocation in distribution planning

    Energy Technology Data Exchange (ETDEWEB)

    Engevall, S

    1997-12-31

    This thesis concerns cost allocation problems in distribution planning. The cost allocation problems we study are illustrated using the distribution planning situation at the Logistics department of Norsk Hydro Olje AB. The planning situation is modeled as a Traveling Salesman Problem and a Vehicle Routing Problem with an inhomogeneous fleet. The cost allocation problems are the problems of how to divide the transportation costs among the customers served in each problem. The cost allocation problems are formulated as cooperative games, in characteristic function form, where the customers are defined to be the players. The games contain five and 21 players respectively. Game theoretical solution concepts such as the core, the nucleolus, the Shapley value and the {tau}-value are discussed. From the empirical results we can, among other things, conclude that the core of the Traveling Salesman Game is large, and that the core of the Vehicle Routing Game is empty. In the accounting of Norsk Hydro the cost per m{sup 3} can be found for each tour. We conclude that for a certain definition of the characteristic function, a cost allocation according to this principle will not be included in the core of the Traveling Salesman Game. The models and methods presented in this thesis can be applied to transportation problems similar to that of Norsk Hydro, independent of the type of products that are delivered. 96 refs, 11 figs, 26 tabs

  13. Hamiltonian cycle problem and Markov chains

    CERN Document Server

    Borkar, Vivek S; Filar, Jerzy A; Nguyen, Giang T

    2014-01-01

    This book summarizes a line of research that maps certain classical problems of discrete mathematics and operations research - such as the Hamiltonian cycle and the Travelling Salesman problems - into convex domains where continuum analysis can be carried out.

  14. A novel method to design S-box based on chaotic map and genetic algorithm

    International Nuclear Information System (INIS)

    Wang, Yong; Wong, Kwok-Wo; Li, Changbing; Li, Yang

    2012-01-01

    The substitution box (S-box) is an important component in block encryption algorithms. In this Letter, the problem of constructing S-box is transformed to a Traveling Salesman Problem and a method for designing S-box based on chaos and genetic algorithm is proposed. Since the proposed method makes full use of the traits of chaotic map and evolution process, stronger S-box is obtained. The results of performance test show that the presented S-box has good cryptographic properties, which justify that the proposed algorithm is effective in generating strong S-boxes. -- Highlights: ► The problem of constructing S-box is transformed to a Traveling Salesman Problem. ► We present a new method for designing S-box based on chaos and genetic algorithm. ► The proposed algorithm is effective in generating strong S-boxes.

  15. A novel method to design S-box based on chaotic map and genetic algorithm

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yong, E-mail: wangyong_cqupt@163.com [State Key Laboratory of Power Transmission Equipment and System Security and New Technology, Chongqing University, Chongqing 400044 (China); Key Laboratory of Electronic Commerce and Logistics, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Wong, Kwok-Wo [Department of Electronic Engineering, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon Tong (Hong Kong); Li, Changbing [Key Laboratory of Electronic Commerce and Logistics, Chongqing University of Posts and Telecommunications, Chongqing 400065 (China); Li, Yang [Department of Automatic Control and Systems Engineering, The University of Sheffield, Mapping Street, S1 3DJ (United Kingdom)

    2012-01-30

    The substitution box (S-box) is an important component in block encryption algorithms. In this Letter, the problem of constructing S-box is transformed to a Traveling Salesman Problem and a method for designing S-box based on chaos and genetic algorithm is proposed. Since the proposed method makes full use of the traits of chaotic map and evolution process, stronger S-box is obtained. The results of performance test show that the presented S-box has good cryptographic properties, which justify that the proposed algorithm is effective in generating strong S-boxes. -- Highlights: ► The problem of constructing S-box is transformed to a Traveling Salesman Problem. ► We present a new method for designing S-box based on chaos and genetic algorithm. ► The proposed algorithm is effective in generating strong S-boxes.

  16. in-town tour optimization town tour optimization town tour

    African Journals Online (AJOL)

    eobe

    operation was formulated as a Traveling Salesman Problem on Excel spreadsheet. The results ... 19.27 %, tour time by 0.33-22.80 %, and fuel consumption. 22.80 %, and fuel ..... solving TSPs and reports a real world in-town tour improvement ...

  17. Robustness of mission plans for unmanned aircraft

    Science.gov (United States)

    Niendorf, Moritz

    This thesis studies the robustness of optimal mission plans for unmanned aircraft. Mission planning typically involves tactical planning and path planning. Tactical planning refers to task scheduling and in multi aircraft scenarios also includes establishing a communication topology. Path planning refers to computing a feasible and collision-free trajectory. For a prototypical mission planning problem, the traveling salesman problem on a weighted graph, the robustness of an optimal tour is analyzed with respect to changes to the edge costs. Specifically, the stability region of an optimal tour is obtained, i.e., the set of all edge cost perturbations for which that tour is optimal. The exact stability region of solutions to variants of the traveling salesman problems is obtained from a linear programming relaxation of an auxiliary problem. Edge cost tolerances and edge criticalities are derived from the stability region. For Euclidean traveling salesman problems, robustness with respect to perturbations to vertex locations is considered and safe radii and vertex criticalities are introduced. For weighted-sum multi-objective problems, stability regions with respect to changes in the objectives, weights, and simultaneous changes are given. Most critical weight perturbations are derived. Computing exact stability regions is intractable for large instances. Therefore, tractable approximations are desirable. The stability region of solutions to relaxations of the traveling salesman problem give under approximations and sets of tours give over approximations. The application of these results to the two-neighborhood and the minimum 1-tree relaxation are discussed. Bounds on edge cost tolerances and approximate criticalities are obtainable likewise. A minimum spanning tree is an optimal communication topology for minimizing the cumulative transmission power in multi aircraft missions. The stability region of a minimum spanning tree is given and tolerances, stability balls

  18. Asymmetric Invisibility Cloaking Theory Based on the Concept of Effective Electromagnetic Fields for Photons

    Science.gov (United States)

    Amemiya, Tomo; Taki, Masato; Kanazawa, Toru; Arai, Shigehisa

    2014-03-01

    The asymmetric invisibility cloak is a special cloak with unidirectional transparency; that is, a person in the cloak should not be seen from the outside but should be able to see the outside. Existing theories of designing invisibility cloaks cannot be used for asymmetric cloaking because they are based on the transformation optics that uses Riemannian metric tensor independent of direction. To overcome this problem, we propose introducing directionality into invisibility cloaking. Our theory is based on ``the theory of effective magnetic field for photons'' proposed by Stanford University.[2] To realize asymmetric cloaking, we have extended the Stanford's theory to add the concept of ``effective electric field for photons.'' The effective electric and the magnetic field can be generated using a photonc resonator lattice, which is a kind of metamaterial. The Hamiltonian for photons in these fields has a similar form to that of the Hamiltonian for a charged particle in an electromagnetic field. An incident photon therefore experiences a ``Lorentz-like'' and a ``Coulomb-like'' force and shows asymmetric movement depending of its travelling direction.We show the procedure of designing actual invisibility cloaks using the photonc resonator lattice and confirm their operation with the aid of computer simulation. This work was supported in part by the MEXT; JSPS KAKENHI Grant Numbers #24246061, #24656046, #25420321, #25420322.

  19. LP formulation of asymmetric zero-sum stochastic games

    KAUST Repository

    Li, Lichun

    2014-12-15

    This paper provides an efficient linear programming (LP) formulation of asymmetric two player zero-sum stochastic games with finite horizon. In these stochastic games, only one player is informed of the state at each stage, and the transition law is only controlled by the informed player. Compared with the LP formulation of extensive stochastic games whose size grows polynomially with respect to the size of the state and the size of the uninformed player\\'s actions, our proposed LP formulation has its size to be linear with respect to the size of the state and the size of the uninformed player, and hence greatly reduces the computational complexity. A travelling inspector problem is used to demonstrate the efficiency of the proposed LP formulation.

  20. LP formulation of asymmetric zero-sum stochastic games

    KAUST Repository

    Li, Lichun; Shamma, Jeff S.

    2014-01-01

    This paper provides an efficient linear programming (LP) formulation of asymmetric two player zero-sum stochastic games with finite horizon. In these stochastic games, only one player is informed of the state at each stage, and the transition law is only controlled by the informed player. Compared with the LP formulation of extensive stochastic games whose size grows polynomially with respect to the size of the state and the size of the uninformed player's actions, our proposed LP formulation has its size to be linear with respect to the size of the state and the size of the uninformed player, and hence greatly reduces the computational complexity. A travelling inspector problem is used to demonstrate the efficiency of the proposed LP formulation.

  1. A rescheduling heuristic for the single machine total tardiness problem

    African Journals Online (AJOL)

    In this paper, we propose a rescheduling heuristic for scheduling N jobs on a .... the schedules which start both jobs i and j after time T, there is an optimal ..... [14] Picard J & Queyranne M, 1978, The time-dependent traveling salesman problem.

  2. The bane of low-dimensionality clustering

    DEFF Research Database (Denmark)

    Cohen-Addad, Vincent; de Mesmay, Arnaud; Rotenberg, Eva

    2018-01-01

    geometric problems such as the traveling salesman problem, or computing an independent set of unit spheres. While these problems benefit from the so-called (limited) blessing of dimensionality, as they can be solved in time nO(k1--1/d) or 2

  3. Reliable Radiation Hybrid Maps: An Efficient Scalable Clustering-based Approach

    Science.gov (United States)

    The process of mapping markers from radiation hybrid mapping (RHM) experiments is equivalent to the traveling salesman problem and, thereby, has combinatorial complexity. As an additional problem, experiments typically result in some unreliable markers that reduce the overall quality of the map. We ...

  4. The Orienteering Problem under Uncertainty Stochastic Programming and Robust Optimization compared

    NARCIS (Netherlands)

    L. Evers (Lanah); K.M. Glorie (Kristiaan); S. van der Ster (Suzanne); A.I. Barros (Ana); H. Monsuur (Herman)

    2012-01-01

    textabstractThe Orienteering Problem (OP) is a generalization of the well-known traveling salesman problem and has many interesting applications in logistics, tourism and defense. To reflect real-life situations, we focus on an uncertain variant of the OP. Two main approaches that deal with

  5. An Effective Implementation of K-opt Moves for the Lin-Kernighan TSP Heuristic

    DEFF Research Database (Denmark)

    Helsgaun, Keld

    Local search with k-change neighborhoods, k-opt, is the most widely used heuristic method for the traveling salesman problem (TSP). This report presents an effective implementation of k-opt for the Lin- Kernighan TSP heuristic. The effectiveness of the implementation is demonstrated with extensive...

  6. The Pyramidal Capacitated Vehicle Routing Problem

    DEFF Research Database (Denmark)

    Lysgaard, Jens

    This paper introduces the Pyramidal Capacitated Vehicle Routing Problem (PCVRP) as a restricted version of the Capacitated Vehicle Routing Problem (CVRP). In the PCVRP each route is required to be pyramidal in a sense generalized from the Pyramidal Traveling Salesman Problem (PTSP). A pyramidal...

  7. The pyramidal capacitated vehicle routing problem

    DEFF Research Database (Denmark)

    Lysgaard, Jens

    2010-01-01

    This paper introduces the pyramidal capacitated vehicle routing problem (PCVRP) as a restricted version of the capacitated vehicle routing problem (CVRP). In the PCVRP each route is required to be pyramidal in a sense generalized from the pyramidal traveling salesman problem (PTSP). A pyramidal...

  8. Conference on Stochastic Processes and their Applications (16th) Held in Stanford, California on 16-21 August 1987.

    Science.gov (United States)

    1987-08-21

    examples of so-called self-similar processes. 522 -°- °.. 0 * - -= uu~.~w- - v , LOCAL BEHAVIOUR OF SIMPLE STOCHASTIC MODELS by Rudolf Grfibel...theorem en- tails results on the growth of matchings, Steiner trees, traveling-salesman processes as well as triangulations in large areas. These

  9. Travel Health Advisory Group: a joint travel industry and travel health Special Interest Group promoting healthy travel in Australia.

    Science.gov (United States)

    Leggat, Peter A; Zwar, Nicholas; Hudson, Bernie

    2012-09-01

    The Travel Health Advisory Group (THAG), established in 1997, is a joint initiative between the travel industry and travel health professionals in Australia that aims to promote healthy travel. THAG seeks to promote cooperation in improving the health of travellers between the travel industry and travel medicine professionals and to raise public awareness of the importance of travel health. From 2011, THAG has been a Special Interest Group of The Australasian College of Tropical Medicine and its membership has been active in several areas, including web-based travel health information, travel health promotion, media releases, research and education in Australia. Information is given on the objectives, membership and an overview of the various activities of the group. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Travel-related health problems in Japanese travelers.

    Science.gov (United States)

    Mizuno, Yasutaka; Kudo, Koichiro

    2009-09-01

    Although the number of Japanese individuals traveling abroad has increased steadily, reaching approximately 17.3 million in 2007, the incidence of various travel-related health problems in Japan remains unknown. The travel-related health problems of Japanese travelers returning to Japan from abroad are analyzed by assessing the records. Data were collected retrospectively on returning travelers who visited the authors' travel clinic during the period from January 2005 through to December 2006 with any health problem acquired overseas. A total of 345 patients were included in this study (200 male, 145 female; average age, 34+/-12.3 years). Reasons for travel included leisure (45.8%); business (39.1%); visiting friends and relatives or accompanying other travelers (8.7%); volunteering (3.8%); and long stays in order to study or live (2.6%). The most visited destination was Asia (n=260), followed by Africa (n=105). The most commonly reported health problems were gastro-intestinal infections (39.1%), followed by respiratory tract infections (16.2%), animal bites (8.1%), and skin problems (5.8%). Together, malaria and dengue accounted for 10% of diagnoses in 125 febrile patients (36.2%). Although the profile of travel-related health problems in Japanese travelers is similar to that of Western travelers, the characteristics of travel were quite different. Therefore Japanese travel advice should be tailored to suit the Japanese traveler.

  11. Efficiency of equilibria in uniform matroid congestion games

    NARCIS (Netherlands)

    de Jong, Jasper; Klimm, Max; Uetz, Marc Jochen

    2016-01-01

    Network routing games, and more generally congestion games play a central role in algorithmic game theory, comparable to the role of the traveling salesman problem in combinatorial optimization. It is known that the price of anarchy is independent of the network topology for non-atomic congestion

  12. An optimization approach for communal home meal delivery service : A case study

    NARCIS (Netherlands)

    Bräysy, Olli; Nakari, Pentti; Dullaert, Wout; Neittaanmäki, Pekka

    2009-01-01

    This paper is the first to discuss the communal home meal delivery problem. The problem can be modelled as a multiple travelling salesman problem with time windows, that is closely related to the well-studied vehicle routing problem with time windows. Experimental results are reported for a

  13. The Orienteering Problem under Uncertainty Stochastic Programming and Robust Optimization compared

    NARCIS (Netherlands)

    Evers, L.; Glorie, K.; Ster, S. van der; Barros, A.I.; Monsuur, H.

    2012-01-01

    The Orienteering Problem (OP) is a generalization of the well-known traveling salesman problem and has many interesting applications in logistics, tourism and defense. To reflect real-life situations, we focus on an uncertain variant of the OP. Two main approaches that deal with optimization under

  14. Investigation and study on each technique and example of intelligent planning; Intelligent planning no kakushu shuho to jirei ni kansuru chosa kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-11

    Various problems on intelligent planning (IP) and the tendency of basic technology were investigated. For each technique of IP, a Petri net and mark graph have been widely used as the modeling and analysis methods of a discrete event system. Moreover, various planning problems were modeled by a traveling salesman problem, and the efficient solution of the traveling salesman problem has been studied simultaneously. The tendency of the basic technology and application system viewed from an example of intelligent plant planning was investigated as an applied field of planning technology, with importance attached to the production system and robot planning. In the scheduling technology of the production system, the activation of an AI study and a new theory (i.e., architecture study) based on natural science information was investigated with the transition in the world as a trigger. A robot system has been planned in a wide range such as the environmental information acquisition planning of a robot. 202 refs., 69 figs., 4 tabs.

  15. Travel characteristics and health practices among travellers at the travellers' health and vaccination clinic in Singapore.

    Science.gov (United States)

    Lee, Vernon J; Wilder-Smith, Annelies

    2006-10-01

    Singapore has a fast-growing travel industry, but few studies have been done on travel characteristics and travel health practices. This study describes the profile and healthseeking behaviour of travellers attending a travel health clinic in Singapore. A cross-sectional survey was conducted on travellers attending the Traveller's Health and Vaccination Centre (THVC) between September and November 2002 using a standardised questionnaire. Information obtained included individual demographic and medical information, travel patterns, vaccination status and travel health practices. Four hundred and ninetyfive (74%) eligible travellers seen at THVC responded to the questionnaire. Their mean age was 36 years; 77% were professionals, managers, executives, and businessmen, students, and white collar workers. Asia was the main travel destination, and most travelled for leisure and resided in hotels or hostels. The median duration of travel was 16 days. Although >90% had previously travelled overseas, only 20% had previously sought pre-travel advice. Malays were significantly underrepresented (P travel advice compared with Chinese, Indians and Malays. Factors associated with seeking pre-travel advice included travel outside of Asia, especially Africa and South America. Singaporean travellers travel more often to cities rather than rural areas, compared with non-Asian travellers. Asia is the preferred destination, and travel outside of Asia is perceived as more risky and is associated with seeking pre-travel advice and vaccinations. Travel patterns and behaviours need to be taken into account when developing evidence-based travel medicine in Asia.

  16. Adewole, ES

    African Journals Online (AJOL)

    ... IV: Normal and Inverted Letter 'h' and 'H' Architecture Abstract · Vol 19 (2011) - Articles Comparison Between Laminar and Turbulent Flow in a Single Phase Horizontal Pipe Gas Flow Abstract · Vol 19 (2011) - Articles Optimization of Gas Flow Network using the Traveling Salesman And the Nearest Neighbors Algorithms

  17. General k-opt submoves for the Lin-Kernighan TSP heuristic

    DEFF Research Database (Denmark)

    Helsgaun, Keld

    2009-01-01

    Local search with k-exchange neighborhoods, k-opt, is the most widely used heuristic method for the traveling salesman problem (TSP). This paper presents an effective implementation of k-opt in LKH-2, a variant of the Lin–Kernighan TSP heuristic. The effectiveness of the implementation...

  18. The Design of a Polymorphous Cognitive Agent Architecture (PCAA)

    Science.gov (United States)

    2008-05-01

    this scenario is very similar to the classic Traveling Salesman Problem (TSP). However, this problem has a strong cognitive aspect , and the goal was to...strong cognitive aspect , and the goal was to focus on this aspect rather than to find a possibly quicker non-cognitive solution. Additionally

  19. A tabu search algorithm for scheduling a single robot in a job-shop environment

    NARCIS (Netherlands)

    Hurink, Johann L.; Knust, S.

    1999-01-01

    We consider a single-machine scheduling problem which arises as a subproblem in a job-shop environment where the jobs have to be transported between the machines by a single transport robot. The robot scheduling problem may be regarded as a generalization of the travelling-salesman problem with time

  20. A tabu search algorithm for scheduling a single robot in a job-shop environment

    NARCIS (Netherlands)

    Hurink, Johann L.; Knust, Sigrid

    2002-01-01

    We consider a single-machine scheduling problem which arises as a subproblem in a job-shop environment where the jobs have to be transported between the machines by a single transport robot. The robot scheduling problem may be regarded as a generalization of the travelling-salesman problem with time

  1. Pre-travel advice seeking from GPs by travellers with chronic illness seen at a travel clinic.

    Science.gov (United States)

    Gagneux-Brunon, Amandine; Andrillat, Carole; Fouilloux, Pascale; Daoud, Fatiha; Defontaine, Christiane; Charles, Rodolphe; Lucht, Frédéric; Botelho-Nevers, Elisabeth

    2016-03-01

    Travellers are ageing and frequently report chronic illness. Pre-travel health advice is crucial, particularly in this subgroup, and general practitioners (GPs) are first in line for treatment adjustment before departure. Our aim is to evaluate pre-travel health advice seeking from GPs by travellers with chronic illness seen at a travel clinic. A cross-sectional observational survey using a questionnaire was conducted between August 2013 and July 2014 in travellers attending the travel medicine clinic of a tertiary university hospital in France. During the study, 2019 travellers were included. Mean age was 39.4 years (±18.8). Three hundred and ninety-one (19.4%) travellers reported a history of a chronic illness. Arterial hypertension and diabetes mellitus were the most frequently reported illnesses, affecting, respectively, 168 (8.3%) travellers and 102 (5.1%). Hajj pilgrims were more likely to report a history of chronic illness than other travellers. Only 810 (40.1%) travellers sought pre-travel advice from their GP. Six hundred and fifty-two (40.1%) healthy travellers and 158 (40.5%) travellers reporting chronic illness sought pre-travel advice from their GP (P = 0.96). Travellers with a history of chronic illness do not seek pre-travel health advice from their GP more frequently than healthy travellers. Travel health specialists are generally not the best practitioners to manage the care of underlying medical conditions presenting risks during travel. However, GPs offer continuity and disease management expertise to improve the specificity of pre-travel planning. Thus, ongoing collaboration between the traveller, GP and travel health specialist is likely to yield the best outcomes. © International Society of Travel Medicine, 2016. All rights reserved. Published by Oxford University Press. For permissions, please e-mail: journals.permissions@oup.com.

  2. Pre-Travel Medical Preparation of Business and Occupational Travelers

    Science.gov (United States)

    Khan, Nomana M.; Jentes, Emily S.; Brown, Clive; Han, Pauline; Rao, Sowmya R.; Kozarsky, Phyllis; Hagmann, Stefan H.F.; LaRocque, Regina C.; Ryan, Edward T.

    2016-01-01

    Objectives: The aim of the study was to understand more about pre-travel preparations and itineraries of business and occupational travelers. Methods: De-identified data from 18 Global TravEpiNet clinics from January 2009 to December 2012 were analyzed. Results: Of 23,534 travelers, 61% were non-occupational and 39% occupational. Business travelers were more likely to be men, had short times to departure and shorter trip durations, and commonly refused influenza, meningococcal, and hepatitis B vaccines. Most business travelers indicated that employers suggested the pre-travel health consultation, whereas non-occupational travelers sought consultations because of travel health concerns. Conclusions: Sub-groups of occupational travelers have characteristic profiles, with business travelers being particularly distinct. Employers play a role in encouraging business travelers to seek pre-travel consultations. Such consultations, even if scheduled immediately before travel, can identify vaccination gaps and increase coverage. PMID:26479857

  3. Heuristics for Comparing the Lengths of Completed E-TSP Tours: Crossings and Areas

    Science.gov (United States)

    MacGregor, James N.

    2017-01-01

    The article reports three experiments designed to explore heuristics used in comparing the lengths of completed Euclidean Traveling Salesman Problem (E-TSP) tours. The experiments used paired comparisons in which participants judged which of two completed tours of the same point set was shorter. The first experiment manipulated two factors, the…

  4. Exponential lower bounds for polytopes in combinatorial optimization

    NARCIS (Netherlands)

    Fiorini, S. (Samuel); Massar, S. (Serge); Pokutta, S. (Sebastian); Tiwary, H.R. (Hans Raj); De Wolf, R. (Ronald)

    2015-01-01

    textabstractWe solve a 20-year old problem posed by Yannakakis and prove that no polynomial-size linear program (LP) exists whose associated polytope projects to the traveling salesman polytope, even if the LP is not required to be symmetric. Moreover, we prove that this holds also for the cut

  5. Efficient heuristics for the Rural Postman Problem | Groves | ORiON

    African Journals Online (AJOL)

    A local search framework for the (undirected) Rural Postman Problem (RPP) is presented in this paper. The framework allows local search approaches that have been applied successfully to the well–known Travelling Salesman Problem also to be applied to the RPP. New heuristics for the RPP, based on this framework, ...

  6. An Exact Method for the Double TSP with Multiple Stacks

    DEFF Research Database (Denmark)

    Lusby, Richard Martin; Larsen, Jesper; Ehrgott, Matthias

    2010-01-01

    The double travelling salesman problem with multiple stacks (DTSPMS) is a pickup and delivery problem in which all pickups must be completed before any deliveries can be made. The problem originates from a real-life application where a 40 foot container (configured as 3 columns of 11 rows) is used...

  7. Formulations and exact algorithms for the vehicle routing problem with time windows

    DEFF Research Database (Denmark)

    Kallehauge, Brian

    2008-01-01

    In this paper we review the exact algorithms proposed in the last three decades for the solution of the vehicle routing problem with time windows (VRPTW). The exact algorithms for the VRPTW are in many aspects inherited from work on the traveling salesman problem (TSP). In recognition of this fact...

  8. Computer aided discovery of families of valid inequalities

    DEFF Research Database (Denmark)

    Røpke, Stefan

    that are violated by a fractional solution supplied by the user. It is up to the user to generalize these examples further. We will present examples of new families of inequalities for the capacitated vehicle routing problem and the traveling salesman problem with pickup and deliveries found using the program....

  9. An Exact Method for the Double TSP with Multiple Stacks

    DEFF Research Database (Denmark)

    Larsen, Jesper; Lusby, Richard Martin; Ehrgott, Matthias

    The double travelling salesman problem with multiple stacks (DTSPMS) is a pickup and delivery problem in which all pickups must be completed before any deliveries can be made. The problem originates from a real-life application where a 40 foot container (configured as 3 columns of 11 rows) is used...

  10. Travel medicine

    Science.gov (United States)

    Aw, Brian; Boraston, Suni; Botten, David; Cherniwchan, Darin; Fazal, Hyder; Kelton, Timothy; Libman, Michael; Saldanha, Colin; Scappatura, Philip; Stowe, Brian

    2014-01-01

    Abstract Objective To define the practice of travel medicine, provide the basics of a comprehensive pretravel consultation for international travelers, and assist in identifying patients who might require referral to travel medicine professionals. Sources of information Guidelines and recommendations on travel medicine and travel-related illnesses by national and international travel health authorities were reviewed. MEDLINE and EMBASE searches for related literature were also performed. Main message Travel medicine is a highly dynamic specialty that focuses on pretravel preventive care. A comprehensive risk assessment for each individual traveler is essential in order to accurately evaluate traveler-, itinerary-, and destination-specific risks, and to advise on the most appropriate risk management interventions to promote health and prevent adverse health outcomes during travel. Vaccinations might also be required and should be personalized according to the individual traveler’s immunization history, travel itinerary, and the amount of time available before departure. Conclusion A traveler’s health and safety depends on a practitioner’s level of expertise in providing pretravel counseling and vaccinations, if required. Those who advise travelers are encouraged to be aware of the extent of this responsibility and to refer all high-risk travelers to travel medicine professionals whenever possible. PMID:25500599

  11. International business travel: impact on families and travellers.

    Science.gov (United States)

    Espino, C M; Sundstrom, S M; Frick, H L; Jacobs, M; Peters, M

    2002-05-01

    Spouses and staff of the World Bank Group (WBG) were questioned about the impact of international business travel on families and travellers. Dependent variables were self reported stress, concern about the health of the traveller, and negative impact on the family. We hypothesised that several travel factors (independent variables) would be associated with these impacts. These travel factors had to do with the frequency, duration, and predictability of travel and its interference with family activities. Survey forms were developed and distributed to all spouses of travelling staff as well as a small sample of operational staff. Kendall's tau b correlation coefficients of response frequencies were computed with the data from scaled items. Written responses to open ended questions were categorised. Response rates for spouses and staff were 24% and 36%, respectively. Half the spouse sample (n=533) and almost 75% of the staff sample (n=102) reported high or very high stress due to business travel. Self reported spouse stress was associated with six out of eight travel factors. Female spouses, those with children, and younger spouses reported greater stress. Self reported staff stress was significantly associated with four out of nine travel factors. Further insight into how business travel affects families and staff (including children's behavioural changes) and how families cope was gained through responses to written questions. The findings support the notion that lengthy and frequent travel and frequent changes in travel dates which affect family plans, all characteristic of WBG missions, negatively affects many spouses and children (particularly young children) and that the strain on families contributes significantly to the stress staff feel about their travel. Policies or management practices that take into consideration family activities and give staff greater leeway in controlling and refusing travel may help relieve stress.

  12. Does asymmetric correlation affect portfolio optimization?

    Science.gov (United States)

    Fryd, Lukas

    2017-07-01

    The classical portfolio optimization problem does not assume asymmetric behavior of relationship among asset returns. The existence of asymmetric response in correlation on the bad news could be important information in portfolio optimization. The paper applies Dynamic conditional correlation model (DCC) and his asymmetric version (ADCC) to propose asymmetric behavior of conditional correlation. We analyse asymmetric correlation among S&P index, bonds index and spot gold price before mortgage crisis in 2008. We evaluate forecast ability of the models during and after mortgage crisis and demonstrate the impact of asymmetric correlation on the reduction of portfolio variance.

  13. [Pre-travel advice and patient education of Hungarian travellers].

    Science.gov (United States)

    Lengyel, Ingrid; Felkai, Péter

    2018-03-01

    According to international surveys, over half of the travellers face some kind of health issue when travelling. The overwhelming majority of travel-related illnesses can be prevented with pre-travel medical consultations, but the syllabus and content of the consultation have to match the travel habits and culture of the given society. This publication explores the specificities and travel habits of Hungarian travellers. One hundred participants of a travel exhibition completed a survey about their international travel. As the survey was not representative, the data could only be processed through simple statistical methods. However, since the exhibition was presumably attended by those wishing to travel, the conclusions drawn from the results are worth publishing, since no similar survey in Hungary has been published before. Based on the suitable classification of age groups in travel medicine, 11% of the participants were adolescents / young adults (aged 15-24), 81% adults (25-59) and 8% elderly (60-74). Twenty-eight percent of the participants travel multiple times a year, 40% yearly and 32% of them less frequently; 16% of the adults, 8% of the adolescents and 4% of the elderly age group travel multiple times a year. The travel destinations of Hungarian travellers have remained practically unchanged since a study was conducted 13 years ago: the vast majority (95%) travelled within Europe, 2% to the United States, and 11% of them elsewhere. Since Hungarians do not travel to endemic areas, only 5% consulted their general practitioners (GPs) prior to travelling, and 29% did when they had to be vaccinated. Forty-two percent of those wishing to travel never consult their GPs, even though 29% of them are aware of some chronic illness. Instead, 51% gather their health information from the internet and only 6% from their doctors. By the contradiction between the poor health status of the majority of Hungarian travellers and the negligence of seeking pre-travel advice

  14. On approximately fair cost allocation in Euclidean TSP games

    NARCIS (Netherlands)

    Faigle, U.; Fekete, Sándor P.; Hochstättler, Winfried; Kern, Walter

    1998-01-01

    We consider the problem of allocating the cost of an optimal traveling salesman tour in a fair way among the nodes visited; in particular, we focus on the case where the distance matrix of the underlying TSP problem satisfies the triangle inequality. We thereby use the model of TSP games in the

  15. Computing nonsimple polygons of minimum perimeter

    NARCIS (Netherlands)

    Fekete, S.P.; Haas, A.; Hemmer, M.; Hoffmann, M.; Kostitsyna, I.; Krupke, D.; Maurer, F.; Mitchell, J.S.B.; Schmidt, A.; Schmidt, C.; Troegel, J.

    2018-01-01

    We consider the Minimum Perimeter Polygon Problem (MP3): for a given set V of points in the plane, find a polygon P with holes that has vertex set V , such that the total boundary length is smallest possible. The MP3 can be considered a natural geometric generalization of the Traveling Salesman

  16. Exponential Lower Bounds for Polytopes in Combinatorial Optimization

    NARCIS (Netherlands)

    Fiorini, S.; Massar, S.; Pokutta, S.; Tiwary, H.R.; de Wolf, R.

    2015-01-01

    We solve a 20-year old problem posed by Yannakakis and prove that no polynomial-size linear program (LP) exists whose associated polytope projects to the traveling salesman polytope, even if the LP is not required to be symmetric. Moreover, we prove that this holds also for the cut polytope and the

  17. On the Complexity of Numerical Analysis

    DEFF Research Database (Denmark)

    Miltersen, Peter Bro; Kjeldgaard-Pedersen, Johan; Burgisser, Peter

    2006-01-01

    an integer N, decide whether N is greater than 0. We show that PosSLP lies in the counting hierarchy, and combining our results with work of Tiwari, we show that the Euclidean Traveling Salesman Problem lies in the counting hierarchy - the previous best upper bound for this important problem (in terms...

  18. Fulltext PDF

    Indian Academy of Sciences (India)

    mapffrom a given domain D to the real line and the problem is to find the point in ... number equal to the total distance the salesman would travel ifhe were to visit the ... If the proba- bility of the chain being in i at a given time is 1t Ci), the proba-.

  19. Asymmetric cation-binding catalysis

    DEFF Research Database (Denmark)

    Oliveira, Maria Teresa; Lee, Jiwoong

    2017-01-01

    The employment of metal salts is quite limited in asymmetric catalysis, although it would provide an additional arsenal of safe and inexpensive reagents to create molecular functions with high optical purity. Cation chelation by polyethers increases the salts' solubility in conventional organic...... solvents, thus increasing their applicability in synthesis. The expansion of this concept to chiral polyethers led to the emergence of asymmetric cation-binding catalysis, where chiral counter anions are generated from metal salts, particularly using BINOL-based polyethers. Alkali metal salts, namely KF...... highly enantioselective silylation reactions in polyether-generated chiral environments, and leading to a record-high turnover in asymmetric organocatalysis. This can lead to further applications by the asymmetric use of other inorganic salts in various organic transformations....

  20. NADIM-Travel: A Multiagent Platform for Travel Services Aggregation

    OpenAIRE

    Ben Ameur, Houssein; Bédard, François; Vaucher, Stéphane; Kropf, Peter; Chaib-draaa, Brahim; Gérin-Lajoie, Robert

    2010-01-01

    With the Internet as a growing channel for travel services distribution, sophisticated travel services aggregators are increasingly in demand. A travel services aggregation platform should be able to manage the heterogeneous characteristics of the many existing travel services. It should also be as scalable, robust, and flexible as possible. Using multiagent technology, we designed and implemented a multiagent platform for travel services aggregation called NADIM-Travel. In this platform, a p...

  1. Travel health attitudes among Turkish business travellers to African countries.

    Science.gov (United States)

    Selcuk, Engin Burak; Kayabas, Uner; Binbasioglu, Hulisi; Otlu, Baris; Bayindir, Yasar; Bozdogan, Bulent; Karatas, Mehmet

    The number of international travellers is increasing worldwide. Although health risks related to international travel are important and generally well-understood, the perception of these risks was unclear among Turkish travellers. We aimed to evaluate the attitudes and health risk awareness of Turkish travellers travelling to African countries. A survey was performed of Turkish travellers bound for Africa from Istanbul International Ataturk Airport in July 2013. A total of 124 travellers were enrolled in the study. Among them, 62.9% had information about their destination but only 11.3% had looked for information on health problems related to travel and their destination. Of all travellers, 53.2% had at least one vaccination before travelling. The most commonly administered vaccine was for typhoid. Among the travellers, 69.3% and 80.6% had "no idea" about yellow fever vaccination and malaria prophylaxis, respectively. A positive correlation was found between a higher level of travellers' education and receiving the recommended vaccination for the destination. Our study revealed significant gaps in the vaccination and chemoprophylaxis uptake of Turkish travellers departing to Africa. An awareness and training program should be developed for travellers, as well as public health workers, to address health risks related to travel. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Characteristics and pre-travel preparation of travelers at a Canadian pediatric tertiary care travel clinic: A retrospective analysis.

    Science.gov (United States)

    Ma, Xiao Wei; Pell, Lisa G; Akseer, Nadia; Khan, Sarah; Lam, Ray E; Louch, Debra; Science, Michelle; Morris, Shaun K

    2016-01-01

    International travelers are susceptible to a wide spectrum of travel related morbidities. Despite rising number of international travelers in Canada, the demographics, risk profiles, and preventative strategies of high-risk traveler groups, including pediatric travelers visiting friends and relatives (VFRs) are not well described. A descriptive analysis was conducted on pre-travel consultations completed between January 2013 and August 2014 at a large pediatric tertiary care center in Toronto, Canada. Data on demographics, travel characteristics, and pre-travel interventions were extracted from 370 pre-travel consultations. Results were compared between all VFR and non-VFR travelers, as well as between children traveling to visit friends and relatives, for vacation, and for education and/or volunteer purposes. Forty-eight percent of consultations were for children travel to visit friends and/or relatives than for other purposes (29% vs 9%, p travel for >28 days than children traveling for vacation (43% vs 1%, p traveling for education/volunteer purposes (43% vs 21%, p = 0.03). Around half of cVFRs traveled to destinations in Asia (51%). The majority stayed with locals, friends and/or relatives (85%), and nearly all traveled to urban destinations (98%). The most prescribed interventions for children were azithromycin (84%), Dukoral (66%), and the hepatitis A vaccine (60%). Atovaquone/proguanil was the most commonly prescribed antimalarial for children. Children that travel to visit friends and relatives represent a unique travel group and may require specific considerations during pre-travel preparations. Our findings can help develop targeted pre-travel strategies for children VFRs. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Travellers' profile, travel patterns and vaccine practices--a 10-year prospective study in a Swiss Travel Clinic.

    Science.gov (United States)

    Boubaker, Rim; Meige, Pierrette; Mialet, Catherine; Buffat, Chantal Ngarambe; Uwanyiligira, Mediatrice; Widmer, Francine; Rochat, Jacynthe; Fossati, Annie Hérard; Souvannaraj-Blanchant, Manisinh; Payot, Sylvie; Rochat, Laurence; de Vallière, Serge; Genton, Blaise; D'Acremont, Valérie

    2016-01-01

    The travel clinic in Lausanne serves a catchment area of 700 000 of inhabitants and provides pre- and post-travel consultations. This study describes the profile of attendees before departure, their travel patterns and the travel clinic practices in terms of vaccination over time. We included all pre-travel first consultation data recorded between November 2002 and December 2012 by a custom-made program DIAMM/G. We analysed client profiles, travel characteristics and vaccinations prescribed over time. Sixty-five thousand and forty-six client-trips were recorded. Fifty-one percent clients were female. Mean age was 32 years. In total, 0.1% were aged travellers had pre-existing medical conditions. Forty-six percent were travelling to Africa, 35% to Asia, 20% to Latin America and 1% (each) to Oceania and Europe; 19% visited more than one country. India was the most common destination (9.6% of travellers) followed by Thailand (8.6%) and Kenya (6.4%). Seventy-three percent of travellers were planning to travel for ≤ 4 weeks. The main reasons for travel were tourism (75%) and visiting friends and relatives (18%). Sixteen percent were backpackers. Pre-travel advice were sought a median of 29 days before departure. Ninety-nine percent received vaccine(s). The most frequently administered vaccines were hepatitis A (53%), tetanus-diphtheria (46%), yellow fever (39%), poliomyelitis (38%) and typhoid fever (30%). The profile of travel clinic attendees was younger than the general Swiss population. A significant proportion of travellers received vaccinations that are recommended in the routine national programme. These findings highlight the important role of travel clinics to (i) take care of an age group that has little contact with general practitioners and (ii) update vaccination status. The most commonly prescribed travel-related vaccines were for hepatitis A and yellow fever. The question remains to know whether clients do attend travel clinics because of compulsory

  4. Danish long distance travel A study of Danish travel behaviour and the role of infrequent travel activities

    DEFF Research Database (Denmark)

    Knudsen, Mette Aagaard

    2014-01-01

    , this is problematic. The average travel distance has steadily increased during the latest decades together with the increasing motorisation of daily travel and international aviation. Previously most focus has been on domestic daily travel activities, but globalisation has, together with changes in price structures......), the TU overnight survey, and the Danish Tourism Statistics from the Business and Holiday Survey (HBS). This has enabled focus on infrequent travel activities segmented relative to travel purpose, distance threshold, or travelling with overnight stays. At an overall level the thesis has three main.......g. socio-economic variables. The analysis of Danish travel activities described in the three different travel surveys has outlined detailed information on Danish travel behaviour at an aggregated level during the past two decades. It has above all revealed the significant role of leisure travel. Private...

  5. Charge Asymmetric Cosmic Rays as a probe of Flavor Violating Asymmetric Dark Matter

    DEFF Research Database (Denmark)

    Masina, Isabella; Sannino, Francesco

    2011-01-01

    The recently introduced cosmic sum rules combine the data from PAMELA and Fermi-LAT cosmic ray experiments in a way that permits to neatly investigate whether the experimentally observed lepton excesses violate charge symmetry. One can in a simple way determine universal properties of the unknown...... component of the cosmic rays. Here we attribute a potential charge asymmetry to the dark sector. In particular we provide models of asymmetric dark matter able to produce charge asymmetric cosmic rays. We consider spin zero, spin one and spin one-half decaying dark matter candidates. We show that lepton...... flavor violation and asymmetric dark matter are both required to have a charge asymmetry in the cosmic ray lepton excesses. Therefore, an experimental evidence of charge asymmetry in the cosmic ray lepton excesses implies that dark matter is asymmetric....

  6. Demographics, health and travel characteristics of international travellers at a pre-travel clinic in Marseille, France.

    Science.gov (United States)

    Aubry, Camille; Gaudart, Jean; Gaillard, Catherine; Delmont, Jean; Parola, Philippe; Brouqui, Philippe; Gautret, Philippe

    2012-09-01

    With the aim to identify at-risk individuals among a cohort of international travellers, 3442 individuals who sought advice at Marseille travel health centre in 2009 were prospectively included. Demographics, travel characteristics, chronic medical conditions, vaccinations and antimalarial chemoprophylaxis were documented. Chronic medical conditions were reported by 11% of individuals, including hypertension (39%), asthma (20%), thyroid disease (15%) and depression (13%). 4% reported taking a daily medication, and psychotropic and cardiovascular medications were the most commonly used. Older travellers (≥60 years) accounted for 10% of the travellers and the prevalence of chronic medical conditions was 27% in this group. Individuals aged 15 years or less accounted for 13% of the travellers. Age, last minute travel (17%) and neurological and psychiatric diseases were the most frequent factors that influenced Yellow fever vaccination and malaria chemoprophylaxis, with more than one tenth of the travellers reporting at least one risk factor for which adjusted advice may be necessary. Migrants visiting their relatives in their origin country accounted for 14% of travellers and 73% of this group travelled with their family including young children. We demonstrate that a significant proportion of travellers are at-risk (43%) because of their travel conditions (VFR), their age, or their health status, and should be targeted for risk reduction strategies. Copyright © 2012 Elsevier Ltd. All rights reserved.

  7. Optimization Approaches for the Traveling Salesman Problem with Drone

    NARCIS (Netherlands)

    N.A.H. Agatz (Niels); P.C. Bouman (Paul); M.E. Schmidt (Marie)

    2016-01-01

    textabstractThe fast and cost-efficient home delivery of goods ordered online is logistically challenging. Many companies are looking for new ways to cross the last-mile to their customers. One technology-enabled opportunity that recently has received much at- tention is the use of a drone to

  8. Individual traveller health priorities and the pre-travel health consultation.

    Science.gov (United States)

    Flaherty, Gerard T; Chen, Bingling; Avalos, Gloria

    2017-09-01

    The purpose of this study was to examine the principal travel health priorities of travellers. The most frequently selected travel health concerns were accessing medical care abroad, dying abroad, insect bites, malaria, personal safety and travel security threats. The travel health risks of least concern were culture shock, fear of flying, jet lag and sexually transmitted infections. This study is the first to develop a hierarchy of self-declared travel health risk priorities among travellers. © International Society of Travel Medicine, 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  9. Connected Traveler

    Energy Technology Data Exchange (ETDEWEB)

    2016-06-01

    The Connected Traveler framework seeks to boost the energy efficiency of personal travel and the overall transportation system by maximizing the accuracy of predicted traveler behavior in response to real-time feedback and incentives. It is anticipated that this approach will establish a feedback loop that 'learns' traveler preferences and customizes incentives to meet or exceed energy efficiency targets by empowering individual travelers with information needed to make energy-efficient choices and reducing the complexity required to validate transportation system energy savings. This handout provides an overview of NREL's Connected Traveler project, including graphics, milestones, and contact information.

  10. Cyclodextrins in Asymmetric and Stereospecific Synthesis

    Directory of Open Access Journals (Sweden)

    Fliur Macaev

    2015-09-01

    Full Text Available Since their discovery, cyclodextrins have widely been used as green and easily available alternatives to promoters or catalysts of different chemical reactions in water. This review covers the research and application of cyclodextrins and their derivatives in asymmetric and stereospecific syntheses, with their division into three main groups: (1 cyclodextrins promoting asymmetric and stereospecific catalysis in water; (2 cyclodextrins’ complexes with transition metals as asymmetric and stereospecific catalysts; and (3 cyclodextrins’ non-metallic derivatives as asymmetric and stereospecific catalysts. The scope of this review is to systematize existing information on the contribution of cyclodextrins to asymmetric and stereospecific synthesis and, thus, to facilitate further development in this direction.

  11. Principles of asymmetric synthesis

    CERN Document Server

    Gawley, Robert E; Aube, Jeffrey

    2012-01-01

    The world is chiral. Most of the molecules in it are chiral, and asymmetric synthesis is an important means by which enantiopure chiral molecules may be obtained for study and sale. Using examples from the literature of asymmetric synthesis, this book presents a detailed analysis of the factors that govern stereoselectivity in organic reactions. After an explanation of the basic physical-organic principles governing stereoselective reactions, the authors provide a detailed, annotated glossary of stereochemical terms. A chapter on "Practical Aspects of Asymmetric Synthesis" provides a critical overview of the most common methods for the preparation of enantiomerically pure compounds, techniques for analysis of stereoisomers using chromatographic, spectroscopic, and chiroptical methods. The authors then present an overview of the most important methods in contemporary asymmetric synthesis organized by reaction type. Thus, there are four chapters on carbon-carbon bond forming reactions, one chapter on reductions...

  12. Risk factors and pre-travel healthcare of international travellers attending a Dutch travel clinic: a cross-sectional analysis.

    Science.gov (United States)

    Wieten, Rosanne W; van der Schalie, Maurice; Visser, Benjamin J; Grobusch, Martin P; van Vugt, Michèle

    2014-01-01

    The number of international travellers is currently estimated to exceed one billion annually. To address travel related health risks and facilitate risk reduction strategies, detailed knowledge of travellers' characteristics is important. In this cross-sectional study, data of a 20% sample of travellers visiting the Academic Medical Center (AMC) travel clinic Amsterdam from July 2011 to July 2012 was collected. Itineraries and protection versus exposure rates of preventable infectious diseases were mapped and reported according to STROBE guidelines. 1749 travellers were included. South-Eastern Asia, South-America and West-Africa were most frequently visited. 26.2% of the population had pre-existing medical conditions (often cardiovascular). Young and VFR travellers had a longer median travel time (28 and 30 days) compared to the overall population (21 days). Young adult travellers were relatively often vaccinated against hepatitis B (43.9% vs. 20.5%, p travellers. Pre-travel guidelines were well adhered to. Young adult travellers had high-risk itineraries but were adequately protected. Improvement of hepatitis B and rabies protection would be desirable, specifically for VFRs. Copyright © 2014 Elsevier Ltd. All rights reserved.

  13. Virtual Travel Agencies - Tourist Value through Travel Information Systems

    OpenAIRE

    Anckar, Bill

    1999-01-01

    Anckar, B. (1999), ?Virtual Travel Agencies - Tourist Value through Travel Information Systems?. IAMSR Research Report 5/99. Institute for Advanced Management Systems Research, ?bo Akademi University. As electronic commerce enables the tourist service providers to sell their products directly to the consumer, travel agencies are faced with the imminent threat of being by-passed in the travel industry chain in the information age. This paper suggests that virtual travel agencies can compete su...

  14. Travel expenses

    OpenAIRE

    Pištěková, Petra

    2014-01-01

    The thesis "Travel expenses" is dedicated to the travel expenses according to Czech legislation. The aim is to describe the travel reimbursement and to analyze the providing of compensation travel expenses on example of the elementary art school Zruč nad Sázavou. The purpose of this analysis is primarily to find an optimal solution to the problem of determining the place of regular workplace for the travel expenses. The theoretical part focuses on the identification and definition of all prin...

  15. Synthesis method of asymmetric gold particles.

    Science.gov (United States)

    Jun, Bong-Hyun; Murata, Michael; Hahm, Eunil; Lee, Luke P

    2017-06-07

    Asymmetric particles can exhibit unique properties. However, reported synthesis methods for asymmetric particles hinder their application because these methods have a limited scale and lack the ability to afford particles of varied shapes. Herein, we report a novel synthetic method which has the potential to produce large quantities of asymmetric particles. Asymmetric rose-shaped gold particles were fabricated as a proof of concept experiment. First, silica nanoparticles (NPs) were bound to a hydrophobic micro-sized polymer containing 2-chlorotritylchloride linkers (2-CTC resin). Then, half-planar gold particles with rose-shaped and polyhedral structures were prepared on the silica particles on the 2-CTC resin. Particle size was controlled by the concentration of the gold source. The asymmetric particles were easily cleaved from the resin without aggregation. We confirmed that gold was grown on the silica NPs. This facile method for synthesizing asymmetric particles has great potential for materials science.

  16. Travelers' Health: Rubella

    Science.gov (United States)

    ... Stamaril clinics Disease Directory Resources Resources for Travelers Adventure Travel Animal Safety Blood Clots Bug Bites Evite ... Minute Travel Long-Term Travel Mass Gatherings Medical Tourism Mental Health Motion Sickness Natural Disasters Pregnant Travelers ...

  17. STUDI PERBANDINGAN ANTARA ALGORITMA BIVARIATE MARGINAL DISTRIBUTION DENGAN ALGORITMA GENETIKA

    Directory of Open Access Journals (Sweden)

    Chastine Fatichah

    2006-01-01

    Full Text Available Bivariate Marginal Distribution Algorithm is extended from Estimation of Distribution Algorithm. This heuristic algorithm proposes the new approach for recombination of generate new individual that without crossover and mutation process such as genetic algorithm. Bivariate Marginal Distribution Algorithm uses connectivity variable the pair gene for recombination of generate new individual. Connectivity between variable is doing along optimization process. In this research, genetic algorithm performance with one point crossover is compared with Bivariate Marginal Distribution Algorithm performance in case Onemax, De Jong F2 function, and Traveling Salesman Problem. In this research, experimental results have shown performance the both algorithm is dependence of parameter respectively and also population size that used. For Onemax case with size small problem, Genetic Algorithm perform better with small number of iteration and more fast for get optimum result. However, Bivariate Marginal Distribution Algorithm perform better of result optimization for case Onemax with huge size problem. For De Jong F2 function, Genetic Algorithm perform better from Bivariate Marginal Distribution Algorithm of a number of iteration and time. For case Traveling Salesman Problem, Bivariate Marginal Distribution Algorithm have shown perform better from Genetic Algorithm of optimization result. Abstract in Bahasa Indonesia : Bivariate Marginal Distribution Algorithm merupakan perkembangan lebih lanjut dari Estimation of Distribution Algorithm. Algoritma heuristik ini mengenalkan pendekatan baru dalam melakukan rekombinasi untuk membentuk individu baru, yaitu tidak menggunakan proses crossover dan mutasi seperti pada Genetic Algorithm. Bivariate Marginal Distribution Algorithm menggunakan keterkaitan pasangan variabel dalam melakukan rekombinasi untuk membentuk individu baru. Keterkaitan antar variabel tersebut ditemukan selama proses optimasi berlangsung. Aplikasi yang

  18. 77 FR 5252 - Federal Travel Regulation; GSA E-Gov Travel Service (ETS) Transition to E-Gov Travel Service 2...

    Science.gov (United States)

    2012-02-02

    ... Travel Regulation; GSA E-Gov Travel Service (ETS) Transition to E-Gov Travel Service 2 (ETS2) AGENCY..., ETS Program Manager Center for Travel Management (QMCD), Office of Travel and Transportation Services (QMC), at [email protected] or (703) 605-2151. SUPPLEMENTARY INFORMATION: The Federal Travel...

  19. Vaccination knowledge, attitude and practice among Chinese travelers who visit travel clinics in Preparation for international travel.

    Science.gov (United States)

    Zhang, Min; Zhang, Jianming; Hao, Yutong; Fan, ZhengXing; Li, Lei; Li, Yiguang; Ju, Wendong; Zhang, Hong; Liu, Wei; Zhang, Mengzhang; Wu, Di; He, Hongtao

    2016-06-01

    Although international travel has become increasingly more common in main land China, few data are available on vaccination knowledge, attitude and practice (KAP) among Chinese travelers. In each of 14 International Travel Healthcare Centers (ITHCs) situated in mainland China 200 volunteers were recruited for a cross-sectional investigation by questionnaire on KAP related to travel vaccinations. For the evaluation the study subjects were grouped by demographic data, past travel experience, travel destination, duration of stay abroad, purpose of travel. Among the 2,800 Chinese travelers who participated in the study, 67.1% were aware of national and travel vaccination recommendations. The knowledge about vaccine preventable diseases was low. The most common sources (73.4%) of information were requirements by destination countries obtained in connection with the visa application, Chinese companies employing workers/laborers for assignments overseas, and foreign schools. The overall acceptance rate of recommended vaccines was 68.7%, but yellow fever was accepted by 99.8% of the participants when recommended. Among 81.1% respondents who recalled to have received vaccinations in the past, only 25.9% of them brought the old vaccination records with them to their ITHC consultations. The results indicate that increased awareness of the importance of pre-travel vaccination is needed among the travellers in order to improve their KAP. © International Society of Travel Medicine, 2016. All rights reserved. Published by Oxford University Press. For permissions, please e-mail: journals.permissions@oup.com.

  20. Valuation of Travel Time and TravelIer Information

    NARCIS (Netherlands)

    Rietveld, Piet

    2003-01-01

    The value of travel time plays an important role in cost benefit analysis of infrastructureprojects. However, the issue of uncertainty on travel times and the implications this has forestimations of travel time values has received much less attention in the literature. In thispaper we compare

  1. International travel patterns and travel risks for stem cell transplant recipients.

    Science.gov (United States)

    Mikati, Tarek; Griffin, Kenneth; Lane, Dakotah; Matasar, Matthew; Shah, Monika K

    2015-01-01

    Stem cell transplantation (SCT) is being increasingly utilized for multiple medical illnesses. However, there is limited knowledge about international travel patterns and travel-related illnesses of stem cell transplant recipients (SCTRs). An observational cross-sectional study was conducted among 979 SCTRs at Memorial Sloan Kettering Cancer Center using a previously standardized and validated questionnaire. International travel post SCT, pre-travel health advice, exposure risks, and travel-related illnesses were queried. A total of 516 SCTRs completed the survey (55% response rate); of these, 40% were allogeneic SCTRs. A total of 229 (44.3%) respondents reported international travel outside the United States and Canada post SCT. The international travel incidence was 32% [95% confidence interval CI 28-36] within 2 years after SCT. Using multivariable Cox regression analysis, variables significantly associated with international travel within first 2 years after SCT were history of international travel prior to SCT [hazard ratio (HR) = 5.3, 95% CI 2.3-12.0], autologous SCT (HR = 2.6, 95% CI 1.6-2.8), foreign birth (HR = 2.3, 95% CI 1.5-3.3), and high income (HR = 2.0, 95% CI 1.8-3.7). During their first trip, 64 travelers (28%) had traveled to destinations that may have required vaccination or malaria chemoprophylaxis. Only 56% reported seeking pre-travel health advice. Of those who traveled, 16 travelers (7%) became ill enough to require medical attention during their first trip after SCT. Ill travelers were more likely to have visited high-risk areas (60 vs 26%, p = 0.005), to have had a longer mean trip duration (24 vs 12 days, p = 0.0002), and to have visited friends and relatives (69 vs 21%, p travel was common among SCTRs within 2 years after SCT and was mainly to low-risk destinations. Although the overall incidence of travel-related illnesses was low, certain subgroups of travelers were at a significantly higher risk. Pre-travel

  2. Danish long distance travel A study of Danish travel behaviour and the role of infrequent travel activities

    OpenAIRE

    Knudsen, Mette Aagaard; Rich, Jeppe; Nielsen, Otto Anker

    2014-01-01

    Historically there has been a lack of knowledge with respect to long distance travel. Due to the considerable contribution of long distance travel to total travelled kilometres and the related energy consumption from the transport sector and derived impacts on greenhouse emissions, this is problematic. The average travel distance has steadily increased during the latest decades together with the increasing motorisation of daily travel and international aviation. Previously most focus has been...

  3. Travel personae of American pleasure travelers

    DEFF Research Database (Denmark)

    Park, S.; Tussyadiah, Iis; Mazanec, J.A.

    2010-01-01

    Travel style has been shown to be a useful concept for understanding travelers. In this study it is argued that the portfolio of trips (specifically, the portfolio of various trip styles) one takes can be used to describe his/her overall travel persona. Network analysis was used to examine...... personae which, in turn, are related to their choices of places visited and their response to advertising materials. It was concluded that the framework provided by these findings along with new tools on the Internet offer the potential to develop highly personalized communications with existing...

  4. Travel itinerary uncertainty and the pre-travel consultation--a pilot study.

    Science.gov (United States)

    Flaherty, Gerard; Md Nor, Muhammad Najmi

    2016-01-01

    Risk assessment relies on the accuracy of the information provided by the traveller. A questionnaire was administered to 83 consecutive travellers attending a travel medicine clinic. The majority of travellers was uncertain about destinations within countries, transportation or type of accommodation. Most travellers were uncertain if they would be visiting malaria regions. The degree of uncertainty about itinerary potentially impacts on the ability of the travel medicine specialist to perform an adequate risk assessment, select appropriate vaccinations and prescribe malaria prophylaxis. This study reveals high levels of traveller uncertainty about their itinerary which may potentially reduce the effectiveness of their pre-travel consultation. © The Author 2016. Published by Oxford University Press on behalf of International society of travel medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  5. Support for the Annual Meeting (30th) of the Cognitive Science Society

    Science.gov (United States)

    2008-10-01

    2006) Contents Zygmunt Pizlo (2006) Editor’s Introduction Nicholas R. Burns. Michael I). Lee. and Douglas Viekers (2006) Are Individual Differences...Zheng Li, VII I laxhimiisa. and \\\\ alter G. Kropatsch (2006) Traveling Salesman Problem: A Foveating Pyramid Model Volume 1 Issue 2 (2007) Contents ...Backward Counterfactuals Morteza Dehghani, Rumen Iliev, Stefan Kaufmann 1169 Concepts and Categories Thursday, July 24,2008

  6. Increasing referral of at-risk travelers to travel health clinics: evaluation of a health promotion intervention targeted to travel agents.

    Science.gov (United States)

    MacDougall, L A; Gyorkos, T W; Leffondré, K; Abrahamowicz, M; Tessier, D; Ward, B J; MacLean, J D

    2001-01-01

    Increases in travel-related illness require new partnerships to ensure travelers are prepared for health risks abroad. The travel agent is one such partner and efforts to encourage travel agents to refer at-risk travelers to travel health clinics may help in reducing travel-attributable morbidity. A health promotion intervention encouraging travel agents to refer at-risk travelers to travel health clinics was evaluated. Information on the knowledge, attitudes, and behaviors of travel agents before and after the intervention was compared using two self-administered questionnaires. The Wilcoxon signed rank test was used to compare the mean difference in overall scores to evaluate the overall impact of the intervention and also subscores for each of the behavioral construct groupings (attitudes, barriers, intent, and subjective norms). Multiple regression techniques were used to evaluate which travel agent characteristics were independently associated with a stronger effect of the intervention. A small improvement in travel agents overall attitudes and beliefs (p =.03) was found, in particular their intention to refer (p =.01). Sixty-five percent of travel agents self-reported an increase in referral behavior; owners or managers of the agency were significantly more likely to do so than other travel agents (OR = 7.25; 95% CI: 1.64 32.06). Older travel agents, those that worked longer hours and those with some past referral experience, had significantly higher post-intervention scores. Travel agents can be willing partners in referral, and agencies should be encouraged to develop specific referral policies. Future research may be directed toward investigating the role of health education in certification curricula, the effectiveness of different types of health promotion interventions, including Internet-facilitated interventions, and the direct impact that such interventions would have on travelers attending travel health clinics.

  7. Human travel and traveling bedbugs.

    Science.gov (United States)

    Delaunay, Pascal

    2012-12-01

    A dramatic increase of reported bedbug (Cimex lectularius and Cimex hemipterus) infestations has been observed worldwide over the past decade. Bedbug infestations have also been detected across a wide range of travel accommodations, regardless of their comfort and hygiene levels. Travelers are increasingly exposed to the risks of bedbug bites, infestation of personal belongings, and subsequent contamination of newly visited accommodations and their homes. We searched Medline publications via the PubMed database. National bedbug recommendations, textbooks, newspapers, and Centers for Disease Control websites were also searched manually. To detect infested sites, avoid or limit bedbug bites, and reduce the risk of contaminating one's belongings and home, bedbug biology and ecology must be understood. A detailed search of their most classic hiding niches is a key to finding adult bedbugs, nymphs, eggs, and feces or traces of blood from crushed bedbugs. Locally, bedbugs move by active displacement to feed (bite) during the night. Bed, mattress, sofa, and/or curtains are the most frequently infested places. If you find bedbugs, change your room or, even better, the hotel. Otherwise, travelers should follow recommendations for avoiding bedbugs and their bites during the night and apply certain simple rules to avoid infesting other sites or their home. Travelers exposed to bedbugs can minimize the risks of bites and infestation of their belongings, and must also do their civic duty to avoid contributing to the subsequent contamination of other hotels and, finally, home. © 2012 International Society of Travel Medicine.

  8. Asymmetric Evolutionary Games

    Science.gov (United States)

    McAvoy, Alex; Hauert, Christoph

    2015-01-01

    Evolutionary game theory is a powerful framework for studying evolution in populations of interacting individuals. A common assumption in evolutionary game theory is that interactions are symmetric, which means that the players are distinguished by only their strategies. In nature, however, the microscopic interactions between players are nearly always asymmetric due to environmental effects, differing baseline characteristics, and other possible sources of heterogeneity. To model these phenomena, we introduce into evolutionary game theory two broad classes of asymmetric interactions: ecological and genotypic. Ecological asymmetry results from variation in the environments of the players, while genotypic asymmetry is a consequence of the players having differing baseline genotypes. We develop a theory of these forms of asymmetry for games in structured populations and use the classical social dilemmas, the Prisoner’s Dilemma and the Snowdrift Game, for illustrations. Interestingly, asymmetric games reveal essential differences between models of genetic evolution based on reproduction and models of cultural evolution based on imitation that are not apparent in symmetric games. PMID:26308326

  9. Asymmetrical field emitter

    Science.gov (United States)

    Fleming, J.G.; Smith, B.K.

    1995-10-10

    A method is disclosed for providing a field emitter with an asymmetrical emitter structure having a very sharp tip in close proximity to its gate. One preferred embodiment of the present invention includes an asymmetrical emitter and a gate. The emitter having a tip and a side is coupled to a substrate. The gate is connected to a step in the substrate. The step has a top surface and a side wall that is substantially parallel to the side of the emitter. The tip of the emitter is in close proximity to the gate. The emitter is at an emitter potential, and the gate is at a gate potential such that with the two potentials at appropriate values, electrons are emitted from the emitter. In one embodiment, the gate is separated from the emitter by an oxide layer, and the emitter is etched anisotropically to form its tip and its asymmetrical structure. 17 figs.

  10. HIV and travel.

    Science.gov (United States)

    Schuhwerk, M A; Richens, J; Zuckerman, Jane N

    2006-01-01

    There is a high demand for travel among HIV-positive individual. This demand arises partly from those who have benefited from advances in antiretroviral therapy as well as those with disease progression. The key to a successful and uneventful holiday lies in careful pre-trip planning, yet many patients fail to obtain advice before travelling. Travel advice for HIV patients is becoming increasingly specialized. In addition to advice on common travel-related infectious diseases, HIV-positive travellers are strongly advised to carry information with them and they need specific advice regarding country entry restrictions, HIV inclusive travel insurance, safety of travel vaccinations and highly active antiretroviral therapy-related issues. A wide range of relevant issues for the HIV-positive traveller are discussed in this review and useful websites can be found at the end.

  11. Essential travel medicine

    CERN Document Server

    Zuckerman, Jane N; Leggat, Peter

    2015-01-01

    This 1st edition of Essential Travel Medicine provides an excellent concise introduction to the specialty of Travel Medicine. This core text will enable health care practitioners particularly those new to the clinical practice of Travel Medicine, to gain a fundamental understanding of the diverse and complex issues which can potentially affect the health of the many millions of people who undertake international travel. Jane N Zuckerman is joined by Gary W Brunette from CDC and Peter A Leggat from Australia as Editors. Leading international specialists in their fields have contributed authoritative chapters reflecting current knowledge to facilitate best clinical practice in the different aspects of travel medicine. The aim of Essential Travel Medicine is to provide a comprehensive guide to Travel Medicine as well as a fundamental knowledge base to support international undergraduate and postgraduate specialty training programmes in the discipline of Travel Medicine. The 1st edition of Essential Travel ...

  12. A profile of travelers--an analysis from a large swiss travel clinic.

    Science.gov (United States)

    Bühler, Silja; Rüegg, Rolanda; Steffen, Robert; Hatz, Christoph; Jaeger, Veronika K

    2014-01-01

    Globally, the Swiss have one of the highest proportions of the population traveling to tropical and subtropical countries. Large travel clinics serve an increasing number of customers with specific pre-travel needs including uncommon destinations and preexisting medical conditions. This study aims to identify health characteristics and travel patterns of travelers seeking advice in the largest Swiss travel clinic so that tailored advice can be delivered. A descriptive analysis was performed on pre-travel visits between July 2010 and August 2012 at the Travel Clinic of the Institute of Social and Preventive Medicine, University of Zurich, Switzerland. A total of 22,584 travelers sought pre-travel advice. Tourism was the main reason for travel (17,875, 81.5%), followed by visiting friends and relatives (VFRs; 1,715, 7.8%), traveling for business (1,223, 5.6%), and "other reasons" (ie, volunteer work, pilgrimage, study abroad, and emigration; 1,112, 5.1%). The main travel destination was Thailand. In the VFR group, the highest proportions of traveling children (258, 15.1%) and of pregnant or breastfeeding women (23, 3.9%) were observed. Mental disorders were more prominent in VFRs (93, 5.4%) and in travel for "other reasons" (63, 5.7%). The latter stayed for the longest periods abroad; 272 (24.9%) stayed longer than 6 months. VFR travelers received the highest percentage of yellow fever vaccinations (523, 30.5%); in contrast, rabies (269, 24.2%) and typhoid vaccinations (279, 25.1%) were given more often to the "other travel reasons" group. New insights into the characteristics of a selected and large population of Swiss international travelers results in improved understanding of the special needs of an increasingly diverse population and, thus, in targeted preventive advice and interventions. © 2014 International Society of Travel Medicine.

  13. Travelling with HIV

    DEFF Research Database (Denmark)

    Nielsen, Ulla S; Jensen-Fangel, Søren; Pedersen, Gitte

    2014-01-01

    BACKGROUND: We aimed to describe travel patterns, extent of professional pre-travel advice and health problems encountered during travel among HIV-infected individuals. METHODS: During a six-month period a questionnaire was handed out to 2821 adult HIV-infected individuals attending any...... of the eight Danish medical HIV care centers. RESULTS: A total of 763 individuals responded. During the previous two years 49% had travelled outside Europe; 18% had travelled less and 30% were more cautious when choosing travel destination than before the HIV diagnosis. Pre-travel advice was sought by only 38......%, and travel insurance was taken out by 86%. However, 29%/74% did not inform the advisor/the insurance company about their HIV status. Nearly all patients on highly active antiretroviral therapy (HAART) were adherent, but 58% worried about carrying HIV-medicine and 19% tried to hide it. Only 19% experienced...

  14. Asymmetric Propagation Delay-Aware TDMA MAC Protocol for Mobile Underwater Acoustic Sensor Networks

    Directory of Open Access Journals (Sweden)

    A-Ra Cho

    2018-06-01

    Full Text Available The propagation delay in mobile underwater acoustic sensor network (MUASN is asymmetric because of its low sound propagation speed, and this asymmetry grows with the increase in packet travel time, which damages the collision avoidance mechanism of the spatial reuse medium access control (MAC protocols for MUASN. We propose an asymmetric propagation delay-aware time division multiple access (APD-TDMA for a MUASN in which periodic data packet transmission is required for a sink node (SN. Collisions at the SN are avoided by deferring data packet transmission after reception of a beacon packet from the SN, and data packets are arrived at the SN in a packet-train manner. The time-offset, which is the time for a node to wait before the transmission of a data packet after reception of a beacon packet, is determined by estimating the propagation delay over two consecutive cycles such that the idle interval at the SN is minimized, and this time-offset is announced by the beacon packet. Simulation results demonstrate that the APD-TDMA improves the channel access delay and the channel utilization by approximately 20% and 30%, respectively, compared with those of the block time bounded TDMA under the given network conditions.

  15. Cinchona alkaloids in asymmetric organocatalysis

    NARCIS (Netherlands)

    Marcelli, T.; Hiemstra, H.

    2010-01-01

    This article reviews the applications of cinchona alkaloids as asymmetric catalysts. In the last few years, characterized by the resurgence of interest in asymmetric organocatalysis, cinchona derivatives have been shown to catalyze an outstanding array of chemical reactions, often with remarkable

  16. The New England travel market: changes in generational travel patterns

    Science.gov (United States)

    Rodney B. Warnick

    1995-01-01

    The purpose of this study was to examine and explore the New England domestic travel market trends, from 1979 through 1991 within the context of generations. The existing travel markets, who travel to New England, are changing by age cohorts and specifically within different generations. The New England changes in generational travel patterns do not reflect national...

  17. ON PEDIGREE POLYTOPE AND ITS PROPERTIES

    Directory of Open Access Journals (Sweden)

    Tiru S. Arthanari

    2013-07-01

    Full Text Available The fact that linear optimization over a polytope can be done in polynomial time in the input size of the instance, has created renewed interest in studying 0-1 polytopes corresponding to combinatorial optimization problems. Studying their polyhedral structure has resulted in new algorithms to solve very large instances of some difficult problems like the symmetric traveling salesman problem. The multistage insertion formulation (MI given by the author, in 1982, for the symmetric traveling salesman problem (STSP, gives rise to a combinatorial object called the pedigree. The pedigrees are in one-to-one correspondence with Hamiltonian cycles. Given n, the convex hull of all the pedigrees is called the corresponding pedigree polytope. In this article we bring together the research done a little over a decade by the author and his doctoral students, on the pedigree polytope, its structure, membership problem and properties of the MI formulation for the STSP. In addition we summarise some of the computational and other peripheral results relating to pedigree approach to solve the STSP. The pedigree polytope possesses properties not shared by the STSP (tour polytope, which makes it interesting to study the pedigrees, both from theoretical and algorithmic perspectives.

  18. Alternative Asymmetric Stochastic Volatility Models

    NARCIS (Netherlands)

    M. Asai (Manabu); M.J. McAleer (Michael)

    2010-01-01

    textabstractThe stochastic volatility model usually incorporates asymmetric effects by introducing the negative correlation between the innovations in returns and volatility. In this paper, we propose a new asymmetric stochastic volatility model, based on the leverage and size effects. The model is

  19. Asymmetric ion trap

    Science.gov (United States)

    Barlow, Stephan E.; Alexander, Michael L.; Follansbee, James C.

    1997-01-01

    An ion trap having two end cap electrodes disposed asymmetrically about a center of a ring electrode. The inner surface of the end cap electrodes are conformed to an asymmetric pair of equipotential lines of the harmonic formed by the application of voltages to the electrodes. The asymmetry of the end cap electrodes allows ejection of charged species through the closer of the two electrodes which in turn allows for simultaneously detecting anions and cations expelled from the ion trap through the use of two detectors charged with opposite polarity.

  20. On the relationship between travel time and travel distance of commuters

    NARCIS (Netherlands)

    Rietveld, P.; Zwart, A.P.; Wee, van G.P.; Hoorn, van der T.

    1999-01-01

    This paper gives a detailed empirical analysis of the relationships between different indicators of costs of commuting trips by car: difference as the crow flies, shortest travel time according to route planner, corresponding travel distance, and reported travel time. Reported travel times are

  1. The impact of injection anxiety on education of travelers about common travel risks.

    Science.gov (United States)

    Noble, Lorraine M; Farquharson, Lorna; O'Dwyer, Niamh A; Behrens, Ron H

    2014-01-01

    Despite many travelers receiving at least one vaccination during the pre-travel consultation, little is known about travelers' fear of injections and the impact this may have on educating travelers about health risks associated with their trip. This study aimed to investigate: (1) the prevalence of injection anxiety in travelers attending a pre-travel consultation, (2) whether anxiety due to anticipating a vaccination adversely affects recall of information and advice, and (3) whether clinicians can recognize travelers' anxiety, and how they respond to anxious travelers. Consecutive adult travelers (N = 105) attending one of two inner-city travel clinics completed self-report measures of state anxiety, injection anxiety, and symptoms of needle phobia immediately before and after their pre-travel consultation. Clinicians were also asked to rate travelers' anxiety and report any anxiety management strategies. Standardized information was presented during the consultation and recall of information and advice was assessed immediately post-consultation. Delayed recall (24 hours) was assessed for a subsample (20%) of participants. More than one third of travelers reported feeling nervous or afraid when having an injection (39%). Travelers' state anxiety was related to their psychological and physiological reactions to needles, and reduced significantly post-consultation. Recall of information and advice varied, with failure of recall ranging from 2 to 70% across 15 items, and delayed recall being significantly lower. No relationship was found between recall and anxiety. Clinician-rated anxiety moderately correlated with travelers' self-reported anxiety. A significant proportion of travelers experienced injection anxiety when attending the pre-travel consultation, with some travelers reporting symptoms consistent with criteria for Blood Injection Injury phobia. There were important gaps in recall of information and advice about common travel risks. Although no

  2. [The profile of Israeli travelers to developing countries: perspectives of a travel clinic].

    Science.gov (United States)

    Stienlauf, Shmuel; Meltzer, Eyal; Leshem, Eyal; Rendi-Wagner, Pamela; Schwartz, Eli

    2010-09-01

    The number of Israeli travelers is increasing, including the number of travelers to developing countries. This study aimed to characterize the profile of Israeli travelers to developing countries. Data regarding demographics, travel destinations, trip duration and the purpose of travel were collected on travelers attending the pre-travel clinic at the Sheba Medical Center during a period of 9 years. Between the dates 1/1/1999 and 31/12/2007, 42,771 travelers presented for consultation at the Sheba Medical Center pre-travel clinic. The average age was 30.8 +/- 13.4 years and 54% of the travelers were males. The female proportion increased from 42% in 1999 to 49% in 2006. There was a steady increase in the number of travelers attending our clinic, except in 2003 (coinciding with the SARS epidemic). Post-army backpackers (20-25 year-old age group) were only 43% of the travelers. Children (60 years) comprised 4.4% and 4.6% of the travelers, respectively. The favorite destinations were Asia (55%), followed by Latin America (27%) and Africa (13%). The distribution of travel destinations varied significantly during the study period. Of note is the sharp decline in travel to Africa following the terrorist attack in Mombassa, Kenya (November 2002). The median trip duration changed during the study period, from 30 to 45 days, between 1999-2004 and 2005-2007 respectively. The majority (87%) of voyagers traveled for pleasure, 6% went for business, and 7% were representatives of governmental organizations. This study found an increasing diversity in the traveler population (more women, more children and older travelers) and more diversity in travel destinations. Disease outbreaks and terrorist attacks had transient negative impacts on the number of travelers.

  3. Contact Frequency, Travel Time, and Travel Costs for Patients with Rheumatoid Arthritis

    OpenAIRE

    Sørensen, Jan; Linde, Louise; Hetland, Merete Lund

    2014-01-01

    Objectives. To investigate travel time, and travel cost related to contacts with health care providers for patients with rheumatoid arthritis (RA) during a three-month period. Methods. Patient-reported travel time and travel cost were obtained from 2847 patients with RA. Eleven outpatient clinics across Denmark recruited patients to the study. Data collected included frequency, travel time and travel costs for contacts at rheumatology outpatient clinics, other outpatient clinics, general prac...

  4. Challenges to providing pre-travel care for travellers visiting friends and relatives: an audit of a specialist travel medicine clinic.

    Science.gov (United States)

    Rowe, Kate; Chaves, Nadia; Leder, Karin

    2017-09-01

    Travellers visiting friends and relatives (VFRs) often have complex pre-travel needs. We identified the characteristics, destinations, vaccinations and pre-travel advice provided to VFRs and compared these with non-VFR travellers. The significant differences we found suggest that future research should focus on improving the uptake of recommended interventions in VFR travellers. © International Society of Travel Medicine, 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  5. Worst Asymmetrical Short-Circuit Current

    DEFF Research Database (Denmark)

    Arana Aristi, Iván; Holmstrøm, O; Grastrup, L

    2010-01-01

    In a typical power plant, the production scenario and the short-circuit time were found for the worst asymmetrical short-circuit current. Then, a sensitivity analysis on the missing generator values was realized in order to minimize the uncertainty of the results. Afterward the worst asymmetrical...

  6. Travel characteristics and risk-taking attitudes in youths traveling to nonindustrialized countries.

    Science.gov (United States)

    Han, Pauline; Balaban, Victor; Marano, Cinzia

    2010-01-01

    International travel to developing countries is increasing with rising levels of disposable income; this trend is seen in both adults and children. Risk-taking attitude is fundamental to research on the prevention of risky health behaviors, which can be an indicator of the likelihood of experiencing illness or injury during travel. The aim of this study is to investigate whether risk-taking attitudes of youths are associated with travel characteristics and likelihood of experiencing illness or injury while traveling to nonindustrialized countries. Data were analyzed from the 2008 YouthStyles survey, an annual mail survey gathering demographics and health knowledge, attitudes, and practices of individuals from 9 through 18 years of age. Travelers were defined as respondents who reported traveling in the last 12 months to a destination other than the United States, Canada, Europe, Japan, Australia, or New Zealand. Risk-taking attitude was measured by using a four-item Brief Sensation-Seeking Scale. All p values ≤ 0.05 were considered significant. Of 1,704 respondents, 131 (7.7%) traveled in the last 12 months. Females and those with higher household income were more likely to travel (odds ratio = 1.6,1.1). Of those who traveled, 16.7% reported seeking pretravel medical care, with most visiting a family doctor for that care (84.0%). However, one-fifth of respondents reported illness and injury during travel; of these, 83.3% traveled with their parents. Males and older youths had higher mean sensation-seeking scores. Further, travelers had a higher mean sensation-seeking score than nontravelers. Those who did not seek pretravel medical care also had higher mean sensation-seeking scores (p = 0.1, not significant). Our results show an association between risk-taking attitudes and youth travel behavior. However, adult supervision during travel and parental directives prior to travel should be taken into consideration. Communication messages should emphasize the

  7. Process time optimization of robotic remote laser cutting by utilizing customized beam patterns and redundancy space task sequencing

    DEFF Research Database (Denmark)

    Villumsen, Sigurd

    This dissertation is written as a part of the ROBOCUT project which concerns the development of a new laser cutting technology that seeks to increase the performance of traditional and remote laser cutting by using beam shaping technologies. The resulting customized beam patterns are obtained by ...... axes of the laser cutting system and transforming the sequencing problem into a generalized traveling salesman problem (GTSP)....

  8. Inclined asymmetric librations in exterior resonances

    Science.gov (United States)

    Voyatzis, G.; Tsiganis, K.; Antoniadou, K. I.

    2018-04-01

    Librational motion in Celestial Mechanics is generally associated with the existence of stable resonant configurations and signified by the existence of stable periodic solutions and oscillation of critical (resonant) angles. When such an oscillation takes place around a value different than 0 or π , the libration is called asymmetric. In the context of the planar circular restricted three-body problem, asymmetric librations have been identified for the exterior mean motion resonances (MMRs) 1:2, 1:3, etc., as well as for co-orbital motion (1:1). In exterior MMRs the massless body is the outer one. In this paper, we study asymmetric librations in the three-dimensional space. We employ the computational approach of Markellos (Mon Not R Astron Soc 184:273-281, https://doi.org/10.1093/mnras/184.2.273, 1978) and compute families of asymmetric periodic orbits and their stability. Stable asymmetric periodic orbits are surrounded in phase space by domains of initial conditions which correspond to stable evolution and librating resonant angles. Our computations were focused on the spatial circular restricted three-body model of the Sun-Neptune-TNO system (TNO = trans-Neptunian object). We compare our results with numerical integrations of observed TNOs, which reveal that some of them perform 1:2 resonant, inclined asymmetric librations. For the stable 1:2 TNO librators, we find that their libration seems to be related to the vertically stable planar asymmetric orbits of our model, rather than the three-dimensional ones found in the present study.

  9. A branch-and-cut algorithm for the capacitated profitable tour problem

    DEFF Research Database (Denmark)

    Jepsen, Mads Kehlet; Petersen, Bjørn; Spoorendonk, Simon

    2014-01-01

    This paper considers the Capacitated Profitable Tour Problem (CPTP) which is a special case of the Elementary Shortest Path Problem with Resource Constraints (ESPPRC). The CPTP belongs to the group of problems known as traveling salesman problems with profits. In CPTP each customer is associated...... with a profit and a demand and the objective is to find a capacitated tour (rooted in a depot node) that minimizes the total travel distance minus the profit of the visited customers. The CPTP can be recognized as the sub-problem in many column generation applications, where it is traditionally solved through...

  10. Fellow travellers: Working memory and mental time travel in rodents.

    Science.gov (United States)

    Dere, Ekrem; Dere, Dorothea; de Souza Silva, Maria Angelica; Huston, Joseph P; Zlomuzica, Armin

    2017-03-19

    The impairment of mental time travel is a severe cognitive symptom in patients with brain lesions and a number of neuropsychiatric disorders. Whether animals are also able to mentally travel in time both forward and backward is still a matter of debate. In this regard, we have proposed a continuum of mental time travel abilities across different animal species, with humans being the species with the ability to perform most sophisticated forms of mental time travel. In this review and perspective article, we delineate a novel approach to understand the evolution, characteristics and function of human and animal mental time travel. Furthermore, we propose a novel approach to measure mental time travel in rodents in a comprehensive manner using a test battery composed of well-validated and easy applicable tests. Copyright © 2017. Published by Elsevier B.V.

  11. The Concept of Travel Medicine and the Actual Situation of Travel-Related Illnesses.

    Science.gov (United States)

    Tunalı, Varol; Turgay, Nevin

    2017-06-01

    Travel medicine defines all diseases and medical situations that are related to travel. Travel medicine comprises infectious diseases, traumas, altitude sickness, sun burns, embolisms, jet lag, and many more travel-related situations. With the increasing possibility and ease of travel, the number of people who have travelled internationally has exceeded 1.13 billion in 2014, and the revenues of international travel have exceeded 1.25 trillion dollars. With every passing day, international travels are shifting toward the developing countries and to more exotic regions of the world, and travelers tend to be more adventurous and daring, thereby increasing risky behaviors during travels. Traveling plays an important role in transmitting infections such as Zika virus infection, Ebola, avian flu, severe acute respiratory syndrome, Chikungunya, and dengue fever and is the principal reason for the epidemics of these types of infections on a global scale. With this background, we suggest that travel medicine is an important but "neglected" medical discipline as the discipline of Parasitology itself like most parasitic diseases.

  12. Contact frequency, travel time, and travel costs for patients with rheumatoid arthritis

    DEFF Research Database (Denmark)

    Sørensen, Jan; Linde, Louise; Hetland, Merete Lund

    2014-01-01

    Objectives. To investigate travel time, and travel cost related to contacts with health care providers for patients with rheumatoid arthritis (RA) during a three-month period. Methods. Patient-reported travel time and travel cost were obtained from 2847 patients with RA. Eleven outpatient clinics...... across Denmark recruited patients to the study. Data collected included frequency, travel time and travel costs for contacts at rheumatology outpatient clinics, other outpatient clinics, general practitioners, privately practicing medical specialists, inpatient hospitals and accident and emergency...... and 13 € on travelling per contact, corresponding to a total of 4.6 hours and 56 € during the 3-month period. There was great variation in patient travel time and costs, but no statistically significant associations were found with clinical and sociodemographic characteristics. Conclusion. The results...

  13. Reversal modes in asymmetric Ni nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Leighton, B.; Pereira, A. [Departamento de Fisica, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Escrig, J., E-mail: jescrigm@gmail.com [Departamento de Fisica, Universidad de Santiago de Chile (USACH), Avda. Ecuador 3493, 917-0124 Santiago (Chile); Center for the Development of Nanoscience and Nanotechnology (CEDENNA), Avda. Ecuador 3493, 917-0124 Santiago (Chile)

    2012-11-15

    We have investigated the evolution of the magnetization reversal mechanism in asymmetric Ni nanowires as a function of their geometry. Circular nanowires are found to reverse their magnetization by the propagation of a vortex domain wall, while in very asymmetric nanowires the reversal is driven by the propagation of a transverse domain wall. The effect of shape asymmetry of the wire on coercivity and remanence is also studied. Angular dependence of the remanence and coercivity is also addressed. Tailoring the magnetization reversal mechanism in asymmetric nanowires can be useful for magnetic logic and race-track memory, both of which are based on the displacement of magnetic domain walls. Finally, an alternative method to detect the presence of magnetic drops is proposed. - Highlights: Black-Right-Pointing-Pointer Asymmetry strongly modifies the magnetic behavior of a wire. Black-Right-Pointing-Pointer Very asymmetric nanowires reverse their magnetization by a transverse domain wall. Black-Right-Pointing-Pointer An alternative method to detect the presence of magnetic drops is proposed. Black-Right-Pointing-Pointer Tailoring the reversal mode in asymmetric nanowires can be useful for potential applications.

  14. Contact frequency, travel time, and travel costs for patients with rheumatoid arthritis.

    Science.gov (United States)

    Sørensen, Jan; Linde, Louise; Hetland, Merete Lund

    2014-01-01

    Objectives. To investigate travel time, and travel cost related to contacts with health care providers for patients with rheumatoid arthritis (RA) during a three-month period. Methods. Patient-reported travel time and travel cost were obtained from 2847 patients with RA. Eleven outpatient clinics across Denmark recruited patients to the study. Data collected included frequency, travel time and travel costs for contacts at rheumatology outpatient clinics, other outpatient clinics, general practitioners, privately practicing medical specialists, inpatient hospitals and accident and emergency departments. Results. Over a 3-month period, patients with RA had on average 4.4 (sd 5.7) contacts with health care providers, of which 2.8 (sd 4.0) contacts were with rheumatology outpatient clinics. Private car and public travel were the most frequent modes of travel. The average patient spent 63 minutes and 13 € on travelling per contact, corresponding to a total of 4.6 hours and 56 € during the 3-month period. There was great variation in patient travel time and costs, but no statistically significant associations were found with clinical and sociodemographic characteristics. Conclusion. The results show that patients with RA spend private time and costs on travelling when they seek treatment. These findings are particularly important when analyzing social costs associated with RA.

  15. Validation of a multimodal travel simulator with travel information provision

    NARCIS (Netherlands)

    Chorus, C.G.; Molin, E.J.E.; Arentze, T.A.; Hoogendoorn, S.P.; Timmermans, H.J.P.; Wee, van G.P.

    2007-01-01

    This paper presents a computer based travel simulator for collecting data concerning the use of next-generation ATIS and their effects on traveler decision making in a multimodal travel environment. The tool distinguishes itself by presenting a completely abstract multimodal transport network, where

  16. Do British travel agents provide adequate health advice for travellers?

    Science.gov (United States)

    Lawlor, D A; Burke, J; Bouskill, E; Conn, G; Edwards, P; Gillespie, D

    2000-01-01

    Travel-related illness is a burden for primary care, with more than two million travellers consulting a general practitioner each year. The annual cost of travel-related illness in the United Kingdom is 11 million Pounds. Travel agents are in a unique position to influence this burden as the most common and most serious problems are preventable with simple advice and/or immunisation. This study, using covert researchers, suggests this potential is not being fully utilised. PMID:10954940

  17. International Travelers' Sociodemographic, Health, and Travel Characteristics: An Italian Study.

    Science.gov (United States)

    Troiano, Gianmarco; Mercone, Astrid; Bagnoli, Alessandra; Nante, Nicola

    Approximately the 8% of travelers requires medical care, with the diagnosis of a vaccine-preventable disease. The aim of our study was to analyze the socio-demographic, health and travel characteristics of the Italian international travelers. We conducted a cross sectional study from January 2015 to June 2016, at the Travel Medicine Clinic of Siena, asking the doctor to interview patients who attended the Clinic, recording socio-demographic and travel information, malaria prophylaxis, vaccinations. The data were organized in a database and processed by software Stata®. We collected 419 questionnaires. Patients chose 71 countries for their travels; the favorite destinations were: India (6.31%), Thailand (6.31%), and Brazil (5.10%). The mean length of stay was 36.17 days. Italians, students, and freelancers tended to stay abroad for a longer time (mean: 36.4 days, 59.87 days and 64.16 days respectively). 33.17% of our sample used drugs for malaria chemoprophylaxis: 71.9% of them used Atovaquone/Proguanil (Malarone®), 26.6% used Mefloquine (Lariam®), 1.5% other drugs. The vaccinations that travelers mostly got in our study were to prevent hepatitis A (n = 264), the typhoid fever (n = 187), the Tetanus + Diphtheria + Pertussis (n = 165), the Yellow fever (n = 118) and the cholera (n = 78). Twenty-eight (6.68%) refused some recommended vaccinations. The vaccines mostly refused were for Typhoid fever (n = 20), hepatitis a (n = 9), and cholera (n = 9). Our results demonstrated that Italian international travelers are at-risk because of their poor vaccinations adherence. This implies that pre-travel counseling is fundamental to increase the knowledge of the risks and the compliance of future travelers. Copyright © 2016 Icahn School of Medicine at Mount Sinai. Published by Elsevier Inc. All rights reserved.

  18. Comparison of neural networks for solving the travelling salesman problem

    NARCIS (Netherlands)

    Maire, La B.F.J.; Mladenov, V.M.

    2012-01-01

    The TSP deals with finding a shortest path through a number of cities. This seemingly simple problem is hard to solve because of the amount of possible solutions. Which is why methods that give a good suboptimal solution in a reasonable time are generally used. In this paper three methods were

  19. Travellers' diarrhoea.

    Science.gov (United States)

    Ericsson, Charles D

    2003-02-01

    Risk of travellers' diarrhoea is about 7% in developed countries and 20-50% in the developing world. Options for prevention include education and chemoprophylaxis. Vaccination is a promising but incomplete option. Achieving behaviour modification of food and water choices among tourists is difficult. Bismuth subsalicylate (BSS)-containing compounds are about 62% effective in the prevention of travellers' diarrhoea. Antibiotics are about 84% effective in preventing travellers' diarrhoea. Routine prophylaxis of travellers' diarrhoea, especially with antibiotics, should be discouraged. Oral rehydration is generally important in the treatment of diarrhoea, but travellers' diarrhoea is only infrequently dehydrating in adults. The addition of oral rehydration solutions confers no additional benefit to loperamide in the treatment of travellers' diarrhoea in adults. Presently, the most active of the antibiotics routinely available for treatment are members of the fluoroquinolone group. Antibiotics that are not absorbed such as aztreonam and a rifampicin-like agent, rifaximin, are both effective. The latter might become a therapy of choice once it is routinely available, due to predictably less adverse reactions with a non-absorbed antibiotic. Preliminary results with azithromycin look very promising. Less severe disease can be treated with a variety of non-antibiotic agents (e.g. BSS-containing compounds, loperamide and a calmodulin inhibitor, zaldaride). The combination of an antibiotic and loperamide is superior to treatment with either agent alone in a several studies and is arguably the treatment of choice for distressing travellers' diarrhoea.

  20. Asymmetric cryptography based on wavefront sensing.

    Science.gov (United States)

    Peng, Xiang; Wei, Hengzheng; Zhang, Peng

    2006-12-15

    A system of asymmetric cryptography based on wavefront sensing (ACWS) is proposed for the first time to our knowledge. One of the most significant features of the asymmetric cryptography is that a trapdoor one-way function is required and constructed by analogy to wavefront sensing, in which the public key may be derived from optical parameters, such as the wavelength or the focal length, while the private key may be obtained from a kind of regular point array. The ciphertext is generated by the encoded wavefront and represented with an irregular array. In such an ACWS system, the encryption key is not identical to the decryption key, which is another important feature of an asymmetric cryptographic system. The processes of asymmetric encryption and decryption are formulized mathematically and demonstrated with a set of numerical experiments.

  1. THE DECISION MAKING OF BUSINESS TRAVELLERS IN SELECTING ONLINE TRAVEL PORTALS FOR TRAVEL BOOKING: AN EMPIRICAL STUDY OF DELHI NATIONAL CAPITAL REGION, INDIA

    Directory of Open Access Journals (Sweden)

    Bivek DATTA

    2018-05-01

    Full Text Available The purpose of this paper is to understand the decision making pattern of the Business Travellers in Delhi National Capital Region in India while booking their trips through Online Travel Portals. The study revolves around purchase decision pattern of Business Travellers by investigating their travel decision making style in selecting online travel portals for their trip booking. The authors have adopted the quantitative methodology to achieve the objective of the study. The study is confined purely to the Business Travellers who book their travel through online travel portals. The data was collected through a structured questionnaire. 300 Business Travellers were interviewed at the departure lounge of Indira Gandhi International Airport, New Delhi, India out of which 150 questionnaires were incomplete in many respects and could not be used and only 150 questionnaires were usable resulting in the response rate of 50%. The Analytical Hierarchy process method was adopted to analyze the relative weights assigned by Business Travellers. The present study identifies through literature review the nine fundamental values of internet purchase i.e. product quality, cost, time to receive the product, convenience, time spent, confidentiality, shopping enjoyment, security and environmental impact. The research findings indicate that business travellers value confidentiality, security and product quality the most while choosing the Online Travel Portal to book their trip. The study is primarily centered on the consumer typology approach to study the decision making patterns of business travellers whereas there are other variables such as lifestyle, personality, attitude which can also be investigated. The study is only restricted to Business Travellers decision making pattern pertaining to their travel booking whereas a study can also be undertaken on leisure travellers decision making pattern. The study is restricted to only Delhi National Capital Region

  2. The Tourist Itinerary Travel Loop: historical and contemporary travel characteristics

    OpenAIRE

    Lundgren, Jan O.

    2012-01-01

    In today’s tourist travel, the travel loop represents a very popular itinerary design, although the circumstances under which it is applied, as well as its geographic scale, often differ from the grandiose loop designs of centuries past. During the past couple of decades, a popular kind of new travel has emerged, the cruise-ship travel phenomenon, which often is arranged as quite an extensive itinerary loop. . However, the cruises can also be transoceanic, even global, with the tourist flying...

  3. Contact Frequency, Travel Time, and Travel Costs for Patients with Rheumatoid Arthritis

    Directory of Open Access Journals (Sweden)

    Jan Sørensen

    2014-01-01

    Full Text Available Objectives. To investigate travel time, and travel cost related to contacts with health care providers for patients with rheumatoid arthritis (RA during a three-month period. Methods. Patient-reported travel time and travel cost were obtained from 2847 patients with RA. Eleven outpatient clinics across Denmark recruited patients to the study. Data collected included frequency, travel time and travel costs for contacts at rheumatology outpatient clinics, other outpatient clinics, general practitioners, privately practicing medical specialists, inpatient hospitals and accident and emergency departments. Results. Over a 3-month period, patients with RA had on average 4.4 (sd 5.7 contacts with health care providers, of which 2.8 (sd 4.0 contacts were with rheumatology outpatient clinics. Private car and public travel were the most frequent modes of travel. The average patient spent 63 minutes and 13 € on travelling per contact, corresponding to a total of 4.6 hours and 56 € during the 3-month period. There was great variation in patient travel time and costs, but no statistically significant associations were found with clinical and sociodemographic characteristics. Conclusion. The results show that patients with RA spend private time and costs on travelling when they seek treatment. These findings are particularly important when analyzing social costs associated with RA.

  4. Quantifying social asymmetric structures.

    Science.gov (United States)

    Solanas, Antonio; Salafranca, Lluís; Riba, Carles; Sierra, Vicenta; Leiva, David

    2006-08-01

    Many social phenomena involve a set of dyadic relations among agents whose actions may be dependent. Although individualistic approaches have frequently been applied to analyze social processes, these are not generally concerned with dyadic relations, nor do they deal with dependency. This article describes a mathematical procedure for analyzing dyadic interactions in a social system. The proposed method consists mainly of decomposing asymmetric data into their symmetric and skew-symmetric parts. A quantification of skew symmetry for a social system can be obtained by dividing the norm of the skew-symmetric matrix by the norm of the asymmetric matrix. This calculation makes available to researchers a quantity related to the amount of dyadic reciprocity. With regard to agents, the procedure enables researchers to identify those whose behavior is asymmetric with respect to all agents. It is also possible to derive symmetric measurements among agents and to use multivariate statistical techniques.

  5. On the relationship between travel time and travel distance in the Netherlands

    NARCIS (Netherlands)

    Rietveld, P.; Zwart, B.; van Wee, B.; van der Hoorn, A.I.J.M.

    1999-01-01

    This paper gives a detailed empirical analysis of the relationships between different indicators of costs of commuting trips by car: difference as the crow flies, shortest travel time according to route planner, corresponding travel distance, and reported travel time. Reported travel times are

  6. Trends and characteristics among HIV-infected and diabetic travelers seeking pre-travel advice.

    Science.gov (United States)

    Elfrink, Floor; van den Hoek, Anneke; Sonder, Gerard J B

    2014-01-01

    The number of individuals with a chronic disease increases. Better treatment options have improved chronic patients' quality of life, likely increasing their motivation for travel. This may have resulted in a change in the number of HIV-infected travelers and/or travelers with Diabetes Mellitus (DM) visiting our travel clinic. We retrospectively analyzed the database of the travel clinic of the Public Health Service Amsterdam, between January 2001 and December 2011 and examined the records for patients with these conditions. Of the 25,000 travelers who consult our clinic annually, the proportion of travelers with HIV or DM has increased significantly. A total of 564 HIV-infected travelers visited our clinic. The mean age was 41 years, 86% were male, 43% visited a yellow fever endemic country and 46.5% had a CD4 count Travelers with low CD4 counts traveled significantly more often to visit friends or relatives. A total of 3704 diabetics visited our clinic. The mean age was 55 years, 52% were male, 27% visited a yellow fever endemic country and 36% were insulin-dependent. Insulin-dependent diabetics traveled more often for work than non-insulin-dependent diabetics. Adequately trained and qualified travel health professionals and up-to-date guidelines for travelers with chronic diseases are of increasing importance. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Travelers' health problems and behavior: prospective study with post-travel follow-up.

    Science.gov (United States)

    Vilkman, Katri; Pakkanen, Sari H; Lääveri, Tinja; Siikamäki, Heli; Kantele, Anu

    2016-07-13

    The annual number of international tourist arrivals has recently exceeded one billion, yet surprisingly few studies have characterized travelers' behavior, illness, and risk factors in a prospective setting. Particularly scarce are surveys of data spanning travel, return, and follow-up of the same cohort. This study examines behavior and illness among travelers while abroad, after return home, and at follow-up. Patterns of behavior connected to type of travel and illness are characterized so as to identify risk factors and provide background data for pre-travel advice. Volunteers to this prospective cohort study were recruited at visits to a travel clinic prior to departure. Data on the subjects' health and behavior were collected by questionnaires before and after journeys and over a three-week follow-up. In addition, the subjects were asked to fill in health diaries while traveling. The final study population consisted of 460 subjects, 79 % of whom reported illness during travel or on arrival: 69 % had travelers' diarrhea (TD), 17 % skin problems, 17 % fever, 12 % vomiting, 8 % respiratory tract infection, 4 % urinary tract infection, 2 % ear infection, 4 % gastrointestinal complaints other than TD or vomiting, and 4 % other symptoms. Of all subjects, 10 % consulted a doctor and 0.7 % were hospitalized; 18 % took antimicrobials, with TD as the most common indication (64 %). Ongoing symptoms were reported by 25 % of all travelers upon return home. During the three-week follow-up (return rate 51 %), 32 % of respondents developed new-onset symptoms, 20 % visited a doctor and 1.7 % were hospitalized. Factors predisposing to health problems were identified by multivariable analysis: certain regions (Southern Asia, South-Eastern Asia, and Eastern Africa), female gender, young age, and long travel duration. Despite proper preventive measures like vaccinations, malaria prophylaxis, and travel advice, the majority of our subjects fell ill during or

  8. 78 FR 73702 - Federal Travel Regulation (FTR); Telework Travel Expenses Test Programs

    Science.gov (United States)

    2013-12-09

    ...; Docket Number 2013-0012, Sequence 1] RIN 3090-AJ23 Federal Travel Regulation (FTR); Telework Travel...). ACTION: Final rule. SUMMARY: GSA is amending the Federal Travel Regulation (FTR) to incorporate the Telework Enhancement Act of 2010, which establishes and authorizes telework travel expenses test programs...

  9. International travel and vaccinations.

    OpenAIRE

    Rizvon, M K; Qazi, S; Ward, L A

    1999-01-01

    With the increase in global travel, no disease is beyond the reach of any population. Traveling patients should be advised to follow food and water precautions and encouraged to receive the recommended immunizations. Travel medicine plays a vital role not only in limiting the morbidity of travel-related illnesses but also in limiting the spread of diseases. This article addresses the common issues related to travel, reviews the care of the immunocompromised traveler, and updates the available...

  10. Risk factors and pre-travel healthcare of international travellers attending a Dutch travel clinic: a cross-sectional analysis

    NARCIS (Netherlands)

    Wieten, Rosanne W.; van der Schalie, Maurice; Visser, Benjamin J.; Grobusch, Martin P.; van Vugt, Michèle

    2014-01-01

    The number of international travellers is currently estimated to exceed one billion annually. To address travel related health risks and facilitate risk reduction strategies, detailed knowledge of travellers' characteristics is important. In this cross-sectional study, data of a 20% sample of

  11. Danish travel activities: do we travel more and longer – and to what extent?

    DEFF Research Database (Denmark)

    Knudsen, Mette Aagaard

    Two separate Danish National travel surveys are analysed to outline the amount and extent of national and international travelling during the latest 15-20 years; the national travel survey (TU) describes mainly national daily travel activities, whereas the holiday and business travel survey...... describes national and international travel activities including overnight stay(s). When sampling only respondents with trips above 100 kilometres, they only accounts for around 2% of all daily travel activities, however, this share appears to increase and suggest in general that we do travel longer....... But due to this limited share of trips, the overall impacts of longer distance travelling vanish when considering all daily travel activities. Especially as about 95% of all daily travel destinations range less than 50 kilometres away and in total induce an average trip length of 20 kilometres. If focus...

  12. Travel agents and the prevention of health problems among travelers in Québec.

    Science.gov (United States)

    Provost, Sylvie; Gaulin, Colette; Piquet-Gauthier, Blandine; Emmanuelli, Julien; Venne, Sylvie; Dion, Réjean; Grenier, Jean-Luc; Dessau, Jean-Claude; Dubuc, Martine

    2002-01-01

    Among the factors influencing travelers to seek preventive health advice before departure, the travel agent's recommendation plays an important role. The objective of our study was to document the practices and needs of travel agents in Québec (Canada) in relation to the prevention of health problems among travelers. In June 2000, a cross-sectional descriptive survey was carried out among travel agents from all travel agencies in Québec. One agent per agency was asked to answer our questions. Data were collected using a 32-item telephone questionnaire. Altogether, 708 travel agents from the 948 agencies contacted answered our questionnaire (participation rate: 75%). Most respondents (81%) believed that the travel agent has a role to play in the prevention of health problems among travelers, especially to recommend that travelers consult a travel clinic before departure. Although over 80% of the agents interviewed mentioned recommending a visit to a travel clinic before an organized tour to Thailand or a backpacking trip in Mexico, less than half said they make the same recommendation for a stay in a seaside resort in Mexico. The majority of respondents were acquainted with the services offered in travel health clinics, and these clinics were the source of travel health information most often mentioned by travel agents. However, nearly 60% of the agents questioned had never personally consulted a travel clinic. When asked about the best way to receive information about travelers' health, more than 40% of respondents favoured receiving information newsletters from public health departments regularly whereas 28% preferred the Internet. Despite the limits of this study, our results should help the public health network better target its interventions aimed to inform travel agents on prevention of health problems among travelers.

  13. German travelers' preferences for travel vaccines assessed by a discrete choice experiment.

    Science.gov (United States)

    Poulos, Christine; Curran, Desmond; Anastassopoulou, Anastassia; De Moerlooze, Laurence

    2018-02-08

    Many travelers to regions with endemic infectious diseases do not follow health authorities' recommendations regarding vaccination against vaccine-preventable infectious diseases, before traveling. The determinants of individual travelers' decisions to vaccinate before traveling are largely unknown. This study aimed to provide this information using a discrete choice experiment (DCE) administered to four types of German travelers: (1) business travelers; (2) travelers visiting friends and relatives (VFR); (3) leisure travelers; and (4) backpackers. A DCE survey was developed, pretested and administered online. It included a series of choice questions in which respondents chose between two hypothetical vaccines, each characterized by four disease attributes with varying levels describing the of risk, health impact, curability and transmissibility of the disease they would prevent (described with four disease attributes with varying levels of risk, health impact, curability and transmissibility), and varying levels of four vaccine attributes (duration of protection, number of doses required, time required for vaccination, and vaccine cost). A random-parameters logit model was used to estimate the importance weights each traveler type placed on the various attribute levels. These weights were used to calculate mean monetary equivalents (MMEs) of changes in each attribute (holding all others constant) and of hypothetical disease-vaccine combinations. All traveler types' choices indicated that they attached the greatest importance to the risk and health impact of disease and to the vaccine cost whereas the other disease and vaccine attributes were less important for their decisions about travel vaccines. An option of not choosing any of the vaccine-pairs presented was rarely selected indicating that travelers' generally prefer to be vaccinated rather than not. The MMEs of changes in vaccine attributes indicated a very high variability between the individual travelers

  14. Designing asymmetric multiferroics with strong magnetoelectric coupling

    Science.gov (United States)

    Lu, Xuezeng; Xiang, Hongjun; Rondinelli, James; Materials Theory; Design Group Team

    2015-03-01

    Multiferroics offer exciting opportunities for electric-field control of magnetism. Single-phase multiferroics suitable for such applications at room temperature need much more study. Here, we propose the concept of an alternative type of multiferroics, namely, the ``asymmetric multiferroic.'' In asymmetric multiferroics, two locally stable ferroelectric states are not symmetrically equivalent, leading to different magnetic properties between these two states. Furthermore, we predict from first principles that a Fe-Cr-Mo superlattice with the LiNbO3-type structure is such an asymmetric multiferroic. The strong ferrimagnetism, high ferroelectric polarization, and significant dependence of the magnetic transition temperature on polarization make this asymmetric multiferroic an ideal candidate for realizing electric-field control of magnetism at room temperature. Our study suggests that the asymmetric multiferroic may provide an alternative playground for voltage control of magnetism and find its applications in spintronics and quantum computing.

  15. Chaos of several typical asymmetric systems

    International Nuclear Information System (INIS)

    Feng Jingjing; Zhang Qichang; Wang Wei

    2012-01-01

    The threshold for the onset of chaos in asymmetric nonlinear dynamic systems can be determined using an extended Padé method. In this paper, a double-well asymmetric potential system with damping under external periodic excitation is investigated, as well as an asymmetric triple-well potential system under external and parametric excitation. The integrals of Melnikov functions are established to demonstrate that the motion is chaotic. Threshold values are acquired when homoclinic and heteroclinic bifurcations occur. The results of analytical and numerical integration are compared to verify the effectiveness and feasibility of the analytical method.

  16. Warehouse order-picking process. Order-picker routing problem

    Directory of Open Access Journals (Sweden)

    E. V. Korobkov

    2015-01-01

    Full Text Available This article continues “Warehouse order-picking process” cycle and describes order-picker routing sub-problem of a warehouse order-picking process. It draws analogies between the orderpickers’ routing problem and traveling salesman’s problem, shows differences between the standard problem statement of a traveling salesman and routing problem of warehouse orderpickers, and gives the particular Steiner’s problem statement of a traveling salesman.Warehouse layout with a typical order is represented by a graph, with some its vertices corresponding to mandatory order-picker’s visits and some other ones being noncompulsory. The paper describes an optimal Ratliff-Rosenthal algorithm to solve order-picker’s routing problem for the single-block warehouses, i.e. warehouses with only two crossing aisles, defines seven equivalent classes of partial routing sub-graphs and five transitions used to have an optimal routing sub-graph of a order-picker. An extension of optimal Ratliff-Rosenthal order-picker routing algorithm for multi-block warehouses is presented and also reasons for using the routing heuristics instead of exact optimal algorithms are given. The paper offers algorithmic description of the following seven routing heuristics: S-shaped, return, midpoint, largest gap, aisle-by-aisle, composite, and combined as well as modification of combined heuristics. The comparison of orderpicker routing heuristics for one- and two-block warehouses is to be described in the next article of the “Warehouse order-picking process” cycle.

  17. What proportion of international travellers acquire a travel-related illness? A review of the literature.

    Science.gov (United States)

    Angelo, Kristina M; Kozarsky, Phyllis E; Ryan, Edward T; Chen, Lin H; Sotir, Mark J

    2017-09-01

    As international travel increases, travellers may be at increased risk of acquiring infectious diseases not endemic in their home countries. Many journal articles and reference books related to travel medicine cite that between 22-64% of international travellers become ill during or after travel; however, this information is minimal, outdated and limited by poor generalizability. We aim to provide a current and more accurate estimate of the proportion of international travellers who acquire a travel-related illness. We identified studies via PubMed or travel medicine experts, published between January 1, 1976-December 31, 2016 that included the number of international travellers acquiring a travel-related illness. We excluded studies that focused on a single disease or did not determine a rate based on the total number of travellers. We abstracted information on traveller demographics, trip specifics, study enrollment and follow-up and number of ill travellers and their illnesses. Of 743 studies, nine met the inclusion criteria. The data sources were from North America (four studies) and Europe (five studies). Most travellers were tourists, the most frequent destination regions were Asia and Africa, and the median trip duration ranged from 8-21 days. Six studies enrolled participants at the travellers' pre-travel consultation. All studies collected data through either extraction from the medical record, weekly diaries, or pre- and post-travel questionnaires. Data collection timeframes varied by study. Between 6-87% of travellers became ill across all studies. Four studies provided the best estimate: between 43-79% of travellers who frequently visited developing nations (e.g. India, Tanzania, and Kenya) became ill; travellers most frequently reported diarrhoea. This is the most comprehensive assessment available on the proportion of international travellers that develop a travel-related illness. Additional cohort studies would provide needed data to more precisely

  18. Inter-temporal variation in the travel time and travel cost parameters of transport models

    OpenAIRE

    Börjesson, Maria

    2012-01-01

    The parameters for travel time and travel cost are central in travel demand forecasting models. Since valuation of infrastructure investments requires prediction of travel demand for future evaluation years, inter-temporal variation of the travel time and travel cost parameters is a key issue in forecasting. Using two identical stated choice experiments conducted among Swedish drivers with an interval of 13 years, 1994 and 2007, this paper estimates the inter-temporal variation in travel time...

  19. Two-phase framework for optimal multi-target Lambert rendezvous

    OpenAIRE

    Bang, Jun; Ahn, Jaemyung

    2017-01-01

    This paper proposes a two-phase framework to solve an optimal multi-target Lambert rendezvous problem. The first phase solves a series of single-target rendezvous problems for all departure-arrival object pairs to generate the elementary solutions, which provides candidate rendezvous trajectories (elementary solutions). The second phase formulates a variant of traveling salesman problem (TSP) using the elementary solutions prepared in the first phase and determines the best rendezvous sequenc...

  20. Apprenticeship Learning: Learning to Schedule from Human Experts

    Science.gov (United States)

    2016-06-09

    identified by the heuristic . A spectrum of problems (i.e. traveling salesman, job-shop scheduling, multi-vehicle routing) was represented , as task locations...caus- ing the codification of this knowledge to become labori- ous. We propose a new approach for capturing domain- expert heuristics through a...demonstrate that this approach accu- rately learns multi-faceted heuristics on both a synthetic data set incorporating job-shop scheduling and vehicle

  1. The quantified self during travel: mapping health in a prospective cohort of travellers.

    Science.gov (United States)

    Farnham, Andrea; Furrer, Reinhard; Blanke, Ulf; Stone, Emily; Hatz, Christoph; Puhan, Milo A

    2017-09-01

    Travel medicine research has remained relatively unchanged in the face of rapid expansion of international travel and is unlikely to meet health challenges beyond infectious diseases. Our aim was to identify the range of health outcomes during travel using real-time monitoring and daily reporting of health behaviours and outcomes and identify traveller subgroups who may benefit from more targeted advice before and during travel. We recruited a prospective cohort of travellers ≥ 18 years and planning travel to Thailand for travel clinics in Zurich and Basel (Switzerland). Participants answered demographic, clinical and risk behaviour questionnaires pre-travel and a daily health questionnaire each day during travel using a smartphone application. Environmental and location data were collected passively by GPS. Classification trees were used to identify predictors of health behaviour and outcomes during travel. Non-infectious disease events were relatively common, with 22.7% (17 out of 75 travellers) experiencing an accident, 40.0% ( n  = 30) a wound or cut and 14.7% ( n  = 11) a bite or lick from an animal. Mental health associated events were widely reported, with 80.0% ( n  = 60) reporting lethargy, 34.7% ( n  = 26) anxiety and 34.7% ( n  = 26) feeling tense or irritable. Classification trees identified age, trip length, previous travel experience and having experienced a sports injury in the past year as the most important discriminatory variables for health threats. Our study offers a revolutionary look at an almost real-time timeline of health events and behaviours during travel using mHealth technology. Non-infectious disease related health issues were common in this cohort, despite being largely unaddressed in traditional travel medicine research and suggest a substantial potential for improving evidence-based travel medicine advice. © International Society of Travel Medicine, 2017. Published by Oxford University Press. All rights

  2. Travel health prevention.

    Science.gov (United States)

    Korzeniewski, Krzysztof

    All around the world there has been a rapid growth in the number of international travels. According to the World Tourism Organisation the number of international tourist arrivals reached 1,235 billion in 2016 and continues to grow at a high rate. This has been much due to the development of air transport (including low-cost airlines), increasingly common economic migration, a growing number of travellers visiting friends and relatives, and an increase in medical tourism. With tropical destinations becoming increasingly popular among travellers, doctors have seen a rising number of patients who seek medical advice on health risks prevalent in hot countries and health prevention measures to be taken in tropical destinations, especially where sanitation is poor. The risk for developing a medical condition while staying abroad depends on a variety of factors, including the traveller's general health condition, health prevention measures taken before or during travel (vaccinations, antimalarial chemoprophylaxis, health precautions during air, road and sea travel, proper acclimatisation, prevention of heat injuries, protection against local flora and fauna, personal hygiene, water, food and feeding hygiene), as well as the prevalence of health risk factors in a given location. Health prevention is a precondition for safe travel and maintaining good physical health; in the era of a rapid growth in international tourism it has become of key importance for all travellers.

  3. Towards More Responsible Business Travel : Green Travel Guide for Business Travellers

    OpenAIRE

    Aila, Anu

    2010-01-01

    The purpose of this research type thesis is to find ways how to develop sustainability in business travel. The target is increase the level of understanding and knowledge to respect natural environment and local cultures and find the right channels and ways to raise the knowledge. The study has been done to raise the awareness how business travel can be more sustainable. This thesis analyzes sustainable tourism based on the economic, environmental, and socio-cultural considerations. Green...

  4. Travel risk behaviors as a determinants of receiving pre-travel health consultation and prevention.

    Science.gov (United States)

    Shady, Ibrahim; Gaafer, Mohammed; Bassiony, Lamiaa

    2015-01-01

    An estimated 30-60 % of travelers experience an illness while traveling. The incidence of travel-related illness can be reduced by preventive measures such as those provided by the Traveler Health Clinic (THC) in Kuwait. The present study is an analytical comparative study between groups of travelers visiting the THC during the study period (May 2009 - December 2010) and an age- and gender-matched control group of non-visitors (800 people). Both groups completed a modified pre-departure questionnaire. Bivariate analysis revealed that Kuwaitis (68.2 %), those traveling for work (25.3 %) or leisure (59.5 %), those living in camps (20.4 %) or hotels (64.0 %), and those with knowledge of the THC from the media (28.1 %) or other sources (57.3 %), were more likely to be associated with a high frequency of visits to the THC ( p  travelers heading to Africa (47 %) and South America (10 %) visited the THC more than did others ( P  travel, duration of stay, and choice of travel destination are independent predictors of receiving pre-travel consultation from the THC. Nationality, purpose of travel, length of stay, and travel destination are predictors for receiving a pre-travel consultation from the THC.

  5. Congenital asymmetric crying face: a case report

    Directory of Open Access Journals (Sweden)

    Semra Kara

    2011-12-01

    Full Text Available Congenital asymmetric crying face is an anomalia caused by unilateral absence or weakness of depressor anguli oris muscle The major finding of the disease is the absence or weakness in the outer and lower movement of the commissure during crying. The other expression muscles are normal and the face is symmetric at rest. The asymmetry in congenital asymmetric crying face is most evident during infancy but decreases by age. Congenital asymmetric crying face can be associated with cervicofacial, musclebone, respiratory, genitourinary and central nervous system anomalia. It is diagnosed by physical examination. This paper presents a six days old infant with Congenital asymmetric crying face and discusses the case in terms of diagnosis and disease features.

  6. Pre-travel care for immunocompromised and chronically ill travellers: A retrospective study.

    Science.gov (United States)

    van Aalst, Mariëlle; Verhoeven, Roos; Omar, Freshta; Stijnis, Cornelis; van Vugt, Michèle; de Bree, Godelieve J; Goorhuis, Abraham; Grobusch, Martin P

    2017-09-01

    Immunocompromised and chronically ill travellers (ICCITs) are susceptible to travel related diseases. In ICCITs, pre-travel care regarding vaccinations and prophylactics is complex. We evaluated the protection level by preventive measures in ICCITs by analysing rates of vaccination protection, antibody titres, and the prescription of standby antibiotics. We analysed, and reported according to STROBE guidelines, pre-travel care data for ICCITs visiting the medical pre-travel clinic at the Academic Medical Centre, The Netherlands from 2011 to 2016. We analysed 2104 visits of 1826 ICCITs. Mean age was 46.6 years and mean travel duration 34.5 days. ICCITs on immunosuppressive treatment (29.7%), HIV (17.2%) or diabetes mellitus (10.2%) comprised the largest groups. Most frequently visited countries were Suriname, Indonesia, and Ghana. Most vaccination rates were >90%. Of travellers in high need of hepatitis A and B protection, 56.6 and 75.7%, underwent titre assessments, respectively. Of ICCITs with a respective indication, 50.6% received a prescription for standby antibiotics. Vaccination rates in our study population were overall comparable to those of healthy travellers studied previously in our centre. However, regarding antibody titre assessments and prescription of standby antibiotics, this study demonstrates that uniform pre-travel guidelines for ICCITs are highly needed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. 25 CFR 700.533 - Restrictions affecting travel and travel expense reimbursement.

    Science.gov (United States)

    2010-04-01

    ... having or seeking business with the Commission. (d) Commission employees traveling on official business, as well as employees traveling on personal business, may not accept the use of private airplanes... official business, provided administrative procedures have been followed in making the travel arrangements. ...

  8. Travelling or not?

    DEFF Research Database (Denmark)

    Helles, Rasmus; Lai, Signe Sophus

    2017-01-01

    -12) travelling to multiple countries on several continents. The article shows that there are systematic differences in terms of formal characteristics, themes, and characters’ communicative style between the series that travel and the series that do not. Especially, the analysis finds that the presence of strong...... female lead characters is systematically linked to the positive travel patterns of the series, and that this cuts across different genres of series. The analysis also finds that series, which have explicitly low production values and simple narrative structure, systematically travels poorer....

  9. Dynamic JUNQ inclusion bodies are asymmetrically inherited in mammalian cell lines through the asymmetric partitioning of vimentin.

    Science.gov (United States)

    Ogrodnik, Mikołaj; Salmonowicz, Hanna; Brown, Rachel; Turkowska, Joanna; Średniawa, Władysław; Pattabiraman, Sundararaghavan; Amen, Triana; Abraham, Ayelet-chen; Eichler, Noam; Lyakhovetsky, Roman; Kaganovich, Daniel

    2014-06-03

    Aging is associated with the accumulation of several types of damage: in particular, damage to the proteome. Recent work points to a conserved replicative rejuvenation mechanism that works by preventing the inheritance of damaged and misfolded proteins by specific cells during division. Asymmetric inheritance of misfolded and aggregated proteins has been shown in bacteria and yeast, but relatively little evidence exists for a similar mechanism in mammalian cells. Here, we demonstrate, using long-term 4D imaging, that the vimentin intermediate filament establishes mitotic polarity in mammalian cell lines and mediates the asymmetric partitioning of damaged proteins. We show that mammalian JUNQ inclusion bodies containing soluble misfolded proteins are inherited asymmetrically, similarly to JUNQ quality-control inclusions observed in yeast. Mammalian IPOD-like inclusion bodies, meanwhile, are not always inherited by the same cell as the JUNQ. Our study suggests that the mammalian cytoskeleton and intermediate filaments provide the physical scaffold for asymmetric inheritance of dynamic quality-control JUNQ inclusions. Mammalian IPOD inclusions containing amyloidogenic proteins are not partitioned as effectively during mitosis as their counterparts in yeast. These findings provide a valuable mechanistic basis for studying the process of asymmetric inheritance in mammalian cells, including cells potentially undergoing polar divisions, such as differentiating stem cells and cancer cells.

  10. Health risks, travel preparation, and illness among public health professionals during international travel.

    Science.gov (United States)

    Balaban, Victor; Warnock, Eli; Ramana Dhara, V; Jean-Louis, Lee Ann; Sotir, Mark J; Kozarsky, Phyllis

    2014-01-01

    Few data currently exist on health risks faced by public health professionals (PHP) during international travel. We conducted pre- and post-travel health surveys to assess knowledge, attitudes, and practices (KAP), and illnesses among PHP international travelers. Anonymous surveys were completed by PHP from a large American public health agency who sought a pre-travel medical consult from September 1, 2009, to September 30, 2010. Surveys were completed by 122 participants; travelers went to 163 countries. Of the 122 respondents, 97 (80%) reported at least one planned health risk activity (visiting rural areas, handling animals, contact with blood or body fluids, visiting malarious areas), and 50 (41%) reported exposure to unanticipated health risks. Of the 62 travelers who visited malarious areas, 14 (23%) reported inconsistent or no use of malaria prophylaxis. Illness during travel was reported by 33 (27%) respondents. Most of the PHP travelers in our study reported at least one planned health risk activity, and almost half reported exposure to unanticipated health risks, and one-quarter of travelers to malarious areas reported inconsistent or no use of malaria chemoprophylaxis. Our findings highlight that communication and education outreach for PHP to prevent travel-associated illnesses can be improved. Published by Elsevier Ltd.

  11. Effect of Rainfall on Travel Time and Accuracy of Travel Time prediction with rainfall

    OpenAIRE

    CHUNG, E; EL-FAOUZI, NE; KUWAHARA, M

    2007-01-01

    Travel time is an important parameter to report to travelers. From the user's perspective, accurate predictions and an estimate of their precision are more beneficial than the current travel time since conditions may change significantly before a traveler completes the journey. Past researches have developed travel time prediction models without considering accidents and rain. Normally accident and Rain may cause to increase travel time. Therefore, it may be interesting to consider Rain and a...

  12. Business Model Development for travel agency : Case company - Goh Travel Korea

    OpenAIRE

    Manuilova, Mariia

    2016-01-01

    Millions of tourists visit South Korea every year to experience the culture and a different life style. Moreover, due to economic development, the country has become popular as a study and work destination. As the tourism market is growing, there are many opportunities for travel agencies to find niches in the market. The purpose of this study is to develop a business model for Goh travel Korea – a travel agency for foreign low budget travelers around Korea, to make it more efficient and incr...

  13. Topic Map for Authentic Travel

    OpenAIRE

    Wandsvik, Atle; Zare, Mehdi

    2007-01-01

    E-business is a new trend in Internet use. Authentic travel is an approach to travel and travel business which helps the traveler experience what is authentic in the travel destination. But how can the traveler find those small authentic spots and organize them together to compose a vacation? E-business techniques, combined withTopic Maps, can help.

  14. Long distance travel ‘today’

    DEFF Research Database (Denmark)

    Christensen, Linda

    2014-01-01

    This paper presents an overview of the Dane’s long distance travel. It is a part of the Drivers and Limits project about long distance travel. Long distance travel is in the project defined as infrequent travel with overnight stay. Danes 15-85 years-old travel in average 5.5 long distance travel...... per year og which a third is for international destinations, a third is for domestic second homes and a third are other domestic trips. However, 87% of the kilometres are for international destinations and only 4% are for domestic second homes. Travel activity is very uneven distributed with only half...... of the population having had a journey during the last three month. At the other hand 60% have travelled internationally during the last year and only 2% have never travelled abroad. The paper presents among other things how the travel activity is distributed on travel purpose and mode and how the mode choice...

  15. Multicatalyst system in asymmetric catalysis

    CERN Document Server

    Zhou, Jian

    2014-01-01

    This book introduces multi-catalyst systems by describing their mechanism and advantages in asymmetric catalysis.  Helps organic chemists perform more efficient catalysis with step-by-step methods  Overviews new concepts and progress for greener and economic catalytic reactions  Covers topics of interest in asymmetric catalysis including bifunctional catalysis, cooperative catalysis, multimetallic catalysis, and novel tandem reactions   Has applications for pharmaceuticals, agrochemicals, materials, and flavour and fragrance

  16. Pre-Travel Health Preparation of Pediatric International Travelers: Analysis From the Global TravEpiNet Consortium.

    Science.gov (United States)

    Hagmann, Stefan; LaRocque, Regina C; Rao, Sowmya R; Jentes, Emily S; Sotir, Mark J; Brunette, Gary; Ryan, Edward T

    2013-12-01

    Children frequently travel internationally. Health-related data on such children are limited. We sought to investigate the demographics, health characteristics, and preventive interventions of outbound US international pediatric travelers. We analyzed data from 32 099 travelers presenting for pre-travel healthcare at the Global TravEpiNet (GTEN), a national consortium of 19 travel clinics, from January 1, 2009 to June 6, 2012. A total of 3332 (10%) of all GTEN travelers were children (traveled mostly for leisure (36%) or to visit friends or relatives (VFR) (36%). Most popular destination regions were Africa (41%), Southeast Asia (16%), Central America (16%), and the Caribbean (16%). Compared with children traveling for leisure, VFR children were more likely to present travel consultation (44% vs 28%), intended to travel for 28 days or longer (70% vs 22%), and to travel to Africa (62% vs 32%). Nearly half of the pediatric travelers (46%) received at least 1 routine vaccine, and most (83%) received at least 1 travel-related vaccine. Parents or guardians of one third of the children (30%) refused at least 1 recommended travel-related vaccine. Most pediatric travelers visiting a malaria-endemic country (72%) received a prescription for malaria chemoprophylaxis. Ten percent of travelers seeking pre-travel healthcare at GTEN sites are children. VFR-travel, pre-travel consultation close to time of departure, and refusal of recommended vaccines may place children at risk for travel-associated illness. Strategies to engage pediatric travelers in timely, pre-travel care and improve acceptance of pre-travel healthcare interventions are needed. © The Author 2013. Published by Oxford University Press on behalf of the Pediatric Infectious Diseases Society. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  17. Travel Overview

    Science.gov (United States)

    Search the Division of Finance site DOF State of Alaska Finance Home Content Area Accounting Charge Cards Top Department of Administration logo Alaska Department of Administration Division of Finance Search You are here Administration / Finance / Travel Travel The Department of Administration administers the

  18. Pre-travel care for immunocompromised and chronically ill travellers: A retrospective study

    NARCIS (Netherlands)

    van Aalst, Mariëlle; Verhoeven, Roos; Omar, Freshta; Stijnis, Cornelis; van Vugt, Michèle; de Bree, Godelieve J.; Goorhuis, Abraham; Grobusch, Martin P.

    2017-01-01

    Background: Immunocompromised and chronically ill travellers (ICCITs) are susceptible to travel related diseases. In ICCITs, pre-travel care regarding vaccinations and prophylactics is complex. We evaluated the protection level by preventive measures in ICCITs by analysing rates of vaccination

  19. Use of Gray code in PBIL algorithm for application in recharge of nuclear fuels; Utilização do código Gray no algoritmo PBIL para aplicação na recarga de combustíveis nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Nast, Fernando N.; Silva, Patrick V.; Meneses, Anderson A. M., E-mail: anderson.meneses@pq.cnpq.br [Universidade Federal do Oeste do Para (UNIOESTE), Santarem, PA (Brazil). Lab. de Inteligencia Computacional; Schirru, Roberto, E-mail: schirru@lmp.ufrj.br [Coordenacao de Pos-Graduacao e Pesquisa de Engenharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil). Lab. de Monitoracao de Processos

    2017-07-01

    The In-Core Fuel Management Optimization (OGCIN) problem, or design optimization of Load Patterns (PCs) are denominations for the optimization problem associated with the refueling operation in a reactor nuclear. The OCGIN is considered a problem of difficult resolution, considering aspects of combinatorial optimization and calculations of analysis and physics of reactors. In order to validate algorithms for the OGCIN solution, we use benchmark problems such as the Travelling Salesman Problem (TSP), because it is considered, like OGCIN, an NP-difficult problem. In the present work, we implemented the Population-Based Incremental Learning (PBIL) algorithm with binary coding and Gray coding and applied them to the optimization of the symmetric PCV Oliver30 and Rykel48 asymmetric PCV and implemented only the Gray coding in the OGCIN application of the cycle 7 of the Angra-1 Nuclear Plant, where we compared its performance with binary coding in. The results on average were 1311 and 1327 ppm of Boron for the binary and Gray codifications respectively, emphasizing that the binary codification obtained a maximum value of 1330 ppm, while the Gray code obtained a value of 1401 ppm, showing superiority, since the Boron concentration is an indicator of the PC cycle extension.

  20. Use of Gray code in PBIL algorithm for application in recharge of nuclear fuels

    International Nuclear Information System (INIS)

    Nast, Fernando N.; Silva, Patrick V.; Meneses, Anderson A. M.; Schirru, Roberto

    2017-01-01

    The In-Core Fuel Management Optimization (OGCIN) problem, or design optimization of Load Patterns (PCs) are denominations for the optimization problem associated with the refueling operation in a reactor nuclear. The OCGIN is considered a problem of difficult resolution, considering aspects of combinatorial optimization and calculations of analysis and physics of reactors. In order to validate algorithms for the OGCIN solution, we use benchmark problems such as the Travelling Salesman Problem (TSP), because it is considered, like OGCIN, an NP-difficult problem. In the present work, we implemented the Population-Based Incremental Learning (PBIL) algorithm with binary coding and Gray coding and applied them to the optimization of the symmetric PCV Oliver30 and Rykel48 asymmetric PCV and implemented only the Gray coding in the OGCIN application of the cycle 7 of the Angra-1 Nuclear Plant, where we compared its performance with binary coding in. The results on average were 1311 and 1327 ppm of Boron for the binary and Gray codifications respectively, emphasizing that the binary codification obtained a maximum value of 1330 ppm, while the Gray code obtained a value of 1401 ppm, showing superiority, since the Boron concentration is an indicator of the PC cycle extension

  1. Travel-associated disease among US residents visiting US GeoSentinel clinics after return from international travel.

    Science.gov (United States)

    Hagmann, Stefan H F; Han, Pauline V; Stauffer, William M; Miller, Andy O; Connor, Bradley A; Hale, DeVon C; Coyle, Christina M; Cahill, John D; Marano, Cinzia; Esposito, Douglas H; Kozarsky, Phyllis E

    2014-12-01

    US residents make 60 million international trips annually. Family practice providers need to be aware of travel-associated diseases affecting this growing mobile population. To describe demographics, travel characteristics and clinical diagnoses of US residents who present ill after international travel. Descriptive analysis of travel-associated morbidity and mortality among US travellers seeking care at 1 of the 22 US practices and clinics participating in the GeoSentinel Global Surveillance Network from January 2000 to December 2012. Of the 9624 ill US travellers included in the analysis, 3656 (38%) were tourist travellers, 2379 (25%) missionary/volunteer/research/aid workers (MVRA), 1580 (16%) travellers visiting friends and relatives (VFRs), 1394 (15%) business travellers and 593 (6%) student travellers. Median (interquartile range) travel duration was 20 days (10-60 days). Pre-travel advice was sought by 45%. Hospitalization was required by 7%. Compared with other groups of travellers, ill MVRA travellers returned from longer trips (median duration 61 days), while VFR travellers disproportionately required higher rates of inpatient care (24%) and less frequently had received pre-travel medical advice (20%). Illnesses of the gastrointestinal tract were the most common (58%), followed by systemic febrile illnesses (18%) and dermatologic disorders (17%). Three deaths were reported. Diagnoses varied according to the purpose of travel and region of exposure. Returning ill US international travellers present with a broad spectrum of travel-associated diseases. Destination and reason for travel may help primary health care providers to generate an accurate differential diagnosis for the most common disorders and for those that may be life-threatening. © The Author 2014. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. Parallel patterns determination in solving cyclic flow shop problem with setups

    Directory of Open Access Journals (Sweden)

    Bożejko Wojciech

    2017-06-01

    Full Text Available The subject of this work is the new idea of blocks for the cyclic flow shop problem with setup times, using multiple patterns with different sizes determined for each machine constituting optimal schedule of cities for the traveling salesman problem (TSP. We propose to take advantage of the Intel Xeon Phi parallel computing environment during so-called ’blocks’ determination basing on patterns, in effect significantly improving the quality of obtained results.

  3. Exact Solutions to the Double TSP with Multiple Stacks

    DEFF Research Database (Denmark)

    Petersen, Hanne Løhmann; Archetti, Claudia; Madsen, Oli B.G.

    In the Double Travelling Salesman Problem with Multiple Stacks (DTSPMS) a set of orders is given, each one requiring transportation of one item from a customer in a pickup region to a customer in a delivery region. The vehicle available for the transportation in each region carries a container....... We present different modelling approaches to solving the DTSPMS to optimality and use the solutions obtained to evaluate the quality of previously obtained heuristic solutions....

  4. Heuristics for NP-hard optimization problems - simpler is better!?

    Directory of Open Access Journals (Sweden)

    Žerovnik Janez

    2015-11-01

    Full Text Available We provide several examples showing that local search, the most basic metaheuristics, may be a very competitive choice for solving computationally hard optimization problems. In addition, generation of starting solutions by greedy heuristics should be at least considered as one of very natural possibilities. In this critical survey, selected examples discussed include the traveling salesman, the resource-constrained project scheduling, the channel assignment, and computation of bounds for the Shannon capacity.

  5. Clausewitzian Friction and Future War Revised Edition

    Science.gov (United States)

    2004-01-01

    Hanoverian general Rudolf von Hammerstein was ordered to occupy the town of Menin in southern Belgium, Scharnhorst served as his principal staff offi...their own files. 100 ENDNOTES FOR PAGES 38–41 156 The intractability of the traveling salesman, or Steiner shortest network, problem is as fol- lows...the class of “hard” problems epitomized by the Steiner problem remains “the preeminent problem in theoretical computer science” (Marshall W. Bern and

  6. The New England travel market: generational travel patterns, 1979 to 1996

    Science.gov (United States)

    Rod Warnick

    2002-01-01

    Generations of travelers who select New England as a primary destination are examined over time from the years of 1979 through 1996 and the analysis serves to update an earlier review of generational travel patterns of the region (Warnick, 1994). Changes in travel patterns are noted by overall adjusted annual change rates by demographic and geographic regions of...

  7. Travel Daily China Travel Innovation Summit to Be Held in Beijing

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Guangzhou,China,April 7th- TravelDaily (www.traveldaily.cn), China’s leading online publisher and event organizer with emphasis on trends in the distribution,marketing and technology of the travel and tourism industries,today announced it will partner with PhoCusWright to host the 2009 China Travel Innovation Summit in Beijing from May 12 to 13,2009.

  8. Travel Behavior Change in Older Travelers: Understanding Critical Reactions to Incidents Encountered in Public Transport.

    Science.gov (United States)

    Sundling, Catherine

    2015-11-18

    Accessibility of travel may be better understood if psychological factors underlying change in travel behavior are known. This paper examines older (65+) travelers' motives for changing their travel behavior. These changes are grounded in critical incidents earlier encountered in public-transport travel. A scientific framework is developed based on cognitive and behavioral theory. In 29 individual interviews, travelers' critical reactions (i.e., cognitive, emotional, and/or behavioral) to 77 critical incidents were examined. By applying critical incident technique (CIT), five reaction themes were identified that had generated travel-behavior change: firm restrictions, unpredictability, unfair treatment, complicated trips, and earlier adverse experiences. To improve older travelers' access to public transport, key findings were: (a) service must be designed so as to strengthen the feeling of being in control throughout the journey; (b) extended personal service would increase predictability in the travel chain and decrease travel complexity; consequently, (c) when designing new services and making effective accessibility interventions, policy makers should consider and utilize underlying psychological factors that could direct traveler behavior.

  9. Vortex Dynamics of Asymmetric Heave Plates

    Science.gov (United States)

    Rusch, Curtis; Maurer, Benjamin; Polagye, Brian

    2017-11-01

    Heave plates can be used to provide reaction forces for wave energy converters, which harness the power in ocean surface waves to produce electricity. Heave plate inertia includes both the static mass of the heave plate, as well as the ``added mass'' of surrounding water accelerated with the object. Heave plate geometries may be symmetric or asymmetric, with interest in asymmetric designs driven by the resulting hydrodynamic asymmetry. Limited flow visualization has been previously conducted on symmetric heave plates, but flow visualization of asymmetric designs is needed to understand the origin of observed hydrodynamic asymmetries and their dependence on the Keulegan-Carpenter number. For example, it is hypothesized that the time-varying added mass of asymmetric heave plates is caused by vortex shedding, which is related to oscillation amplitude. Here, using direct flow visualization, we explore the relationship between vortex dynamics and time-varying added mass and drag. These results suggest potential pathways for more advanced heave plate designs that can exploit vortex formation and shedding to achieve more favorable hydrodynamic properties for wave energy converters.

  10. Renewable resource management under asymmetric information

    DEFF Research Database (Denmark)

    Jensen, Frank; Andersen, Peder; Nielsen, Max

    2013-01-01

    Asymmetric information between fishermen and the regulator is important within fisheries. The regulator may have less information about stock sizes, prices, costs, effort, productivity and catches than fishermen. With asymmetric information, a strong analytical tool is principal-agent analysis....... In this paper, we study asymmetric information about productivity within a principal-agent framework and a tax on fishing effort is considered. It is shown that a second best optimum can be achieved if the effort tax is designed such that low-productivity agents rent is exhausted, while high-productivity agents...... receive an information rent. The information rent is equivalent to the total incentive cost. The incentive costs arise as we want to reveal the agent's type....

  11. THE DECISION MAKING OF BUSINESS TRAVELLERS IN SELECTING ONLINE TRAVEL PORTALS FOR TRAVEL BOOKING: AN EMPIRICAL STUDY OF DELHI NATIONAL CAPITAL REGION, INDIA

    OpenAIRE

    Bivek DATTA; Manohar SAJNANI; Joby THOMAS

    2018-01-01

    The purpose of this paper is to understand the decision making pattern of the Business Travellers in Delhi National Capital Region in India while booking their trips through Online Travel Portals. The study revolves around purchase decision pattern of Business Travellers by investigating their travel decision making style in selecting online travel portals for their trip booking. The authors have adopted the quantitative methodology to achieve the objective of the study. The study is confi...

  12. Travel Behavior Change in Older Travelers: Understanding Critical Reactions to Incidents Encountered in Public Transport

    OpenAIRE

    Sundling, Catherine

    2015-01-01

    Accessibility of travel may be better understood if psychological factors underlying change in travel behavior are known. This paper examines older (65+) travelers? motives for changing their travel behavior. These changes are grounded in critical incidents earlier encountered in public-transport travel. A scientific framework is developed based on cognitive and behavioral theory. In 29 individual interviews, travelers? critical reactions (i.e., cognitive, emotional, and/or behavioral) to 77 ...

  13. You, too, can be an international medical traveler: Reading medical travel guidebooks

    NARCIS (Netherlands)

    Ormond, M.E.; Sothern, M.

    2012-01-01

    Drawing on literature on self-help and travel guide writing, this paper interrogates five international medical travel guidebooks aimed at encouraging American and British audiences to travel abroad to purchase medical care. These guidebooks articulate a three-step self-help “program” to produce a

  14. Subcopula-based measure of asymmetric association for contingency tables.

    Science.gov (United States)

    Wei, Zheng; Kim, Daeyoung

    2017-10-30

    For the analysis of a two-way contingency table, a new asymmetric association measure is developed. The proposed method uses the subcopula-based regression between the discrete variables to measure the asymmetric predictive powers of the variables of interest. Unlike the existing measures of asymmetric association, the subcopula-based measure is insensitive to the number of categories in a variable, and thus, the magnitude of the proposed measure can be interpreted as the degree of asymmetric association in the contingency table. The theoretical properties of the proposed subcopula-based asymmetric association measure are investigated. We illustrate the performance and advantages of the proposed measure using simulation studies and real data examples. Copyright © 2017 John Wiley & Sons, Ltd.

  15. Valuing travel time variability: Characteristics of the travel time distribution on an urban road

    DEFF Research Database (Denmark)

    Fosgerau, Mogens; Fukuda, Daisuke

    2012-01-01

    This paper provides a detailed empirical investigation of the distribution of travel times on an urban road for valuation of travel time variability. Our investigation is premised on the use of a theoretical model with a number of desirable properties. The definition of the value of travel time...... variability depends on certain properties of the distribution of random travel times that require empirical verification. Applying a range of nonparametric statistical techniques to data giving minute-by-minute travel times for a congested urban road over a period of five months, we show that the standardized...... travel time is roughly independent of the time of day as required by the theory. Except for the extreme right tail, a stable distribution seems to fit the data well. The travel time distributions on consecutive links seem to share a common stability parameter such that the travel time distribution...

  16. Travel intermediaries and responsibility for compliance with EU travel law : A scattered legal picture

    NARCIS (Netherlands)

    de Vries, Anne

    Travel intermediaries, commonly known as travel agencies, are important and well-known actors in the travel sector and online travel agencies such as Expedia, Booking.com and AirBnB are booming. Although intermediaries obviously bring clear benefits for contracting parties, they also complicate the

  17. Modelling asymmetric growth in crowded plant communities

    DEFF Research Database (Denmark)

    Damgaard, Christian

    2010-01-01

    A class of models that may be used to quantify the effect of size-asymmetric competition in crowded plant communities by estimating a community specific degree of size-asymmetric growth for each species in the community is suggested. The model consists of two parts: an individual size......-asymmetric growth part, where growth is assumed to be proportional to a power function of the size of the individual, and a term that reduces the relative growth rate as a decreasing function of the individual plant size and the competitive interactions from other plants in the neighbourhood....

  18. Representation of Central Asia and Traveling Self in Vambery’s Travels in Central Asia

    Directory of Open Access Journals (Sweden)

    Ahmad Gholi

    2016-03-01

    Full Text Available In the course of the nineteenth century Arminius Vambery, an anglophile travel writer, in the guise of a mendicant dervish with a group of Tartar pilgrims departs to secluded and sealed Central Asia. After six months travel in the Khanates of Central Asia, he undertakes a journey to England where he offers his observations to the Royal Geographical Society and publishes his travelogue, Travel in Central Asia. Despite its literary merits and connection with British imperialism, the travelogue has not been scrutinized separately by the scholars of travel writing. To fill the gap, this article by drawing on the theories of post-structuralism: Orientalism and Postcolonialism, endeavors to unveil the political agenda behind the travel writer’s representation of his travelees, destination, and his own traveling self. Additionally, it argues that the travel writer in dialogue with other Western travel writers to deterritorialize his traversed region or justify the prospective presence of Britain in Central Asia, represents his journey destination as the locus of barbarity, a region under the grip of despotic rulers, as well as an area with frozen time, while to exhibit his Eurocentrism, he portrays his traveling subject as the a suffering hero and a benign traveler.

  19. Travelers' Health: HIV Infection

    Science.gov (United States)

    ... Last-Minute Travel Long-Term Travel Mass Gatherings Medical Tourism Mental Health Motion Sickness Natural Disasters Pregnant Travelers ... for purposes of medical treatment (see Chapter 2, Medical Tourism ), the blood and blood products used in the ...

  20. Intercity Travel Demand Analysis Model

    OpenAIRE

    Ming Lu; Hai Zhu; Xia Luo; Lei Lei

    2014-01-01

    It is well known that intercity travel is an important component of travel demand which belongs to short distance corridor travel. The conventional four-step method is no longer suitable for short distance corridor travel demand analysis for the time spent on urban traffic has a great impact on traveler's main mode choice. To solve this problem, the author studied the existing intercity travel demand analysis model, then improved it based on the study, and finally established a combined model...

  1. Asymmetric Frontal Brain Activity and Parental Rejection

    NARCIS (Netherlands)

    Huffmeijer, R.; Alink, L.R.A.; Tops, M.; Bakermans-Kranenburg, M.J.; van IJzendoorn, M.H.

    2013-01-01

    Asymmetric frontal brain activity has been widely implicated in reactions to emotional stimuli and is thought to reflect individual differences in approach-withdrawal motivation. Here, we investigate whether asymmetric frontal activity, as a measure of approach-withdrawal motivation, also predicts

  2. Travel opinion leaders and seekers

    DEFF Research Database (Denmark)

    Yoo, Kyung-Hyan; Gretzel, Ulrike; Zach, Florian

    2011-01-01

    While opinion leadership has been recognized as important in tourism, there has been very little empirical research investigating the phenomenon. Given new developments in social media technologies, it is especially important to understand whether travel opinion leadership and seeking are drivers...... of specific social media perceptions and behaviours. Based on an online survey of US online travellers, this paper seeks to identify travel opinion leaders and seekers and their characteristics. Further, the research conducted investigated linkages between travel opinion leadership/seeking and travel social...... media use. The findings suggest that travel opinion leadership and seeking are distinct but connected. Both opinion leaders and seekers are technology savvy, young, educated, involved in travel planning and engaged in social media use for travel. What distinguishes opinion leaders is their greater...

  3. Travel experience ecosystem model : building travel agencies’ business resilience in Portugal

    OpenAIRE

    Salvado, Josefina

    2011-01-01

    The Portuguese tourism distribution recognizes in the digital economy drivers - based on e-business, collaborative networks and information exchange - an incentive to productivity and rendibility, leading to sustainable competitive advantages. Travel agencies live currently in a Darwinian business-oriented environment, where only resilient entrepreneurs are able to survive. This framing allows the genesis of a new theoretical archetype of travel agencies, the “TEEM - Travel Exp...

  4. The Connected Traveler

    Energy Technology Data Exchange (ETDEWEB)

    Young, Stanley

    2017-04-24

    The Connected Traveler project is a multi-disciplinary undertaking that seeks to validate potential for transformative transportation system energy savings by incentivizing energy efficient travel behavior.

  5. Asymmetric dominance and asymmetric mate choice oppose premating isolation after allopatric divergence.

    Science.gov (United States)

    Sefc, Kristina M; Hermann, Caroline M; Steinwender, Bernd; Brindl, Hanna; Zimmermann, Holger; Mattersdorfer, Karin; Postl, Lisbeth; Makasa, Lawrence; Sturmbauer, Christian; Koblmüller, Stephan

    2015-04-01

    Assortative mating promotes reproductive isolation and allows allopatric speciation processes to continue in secondary contact. As mating patterns are determined by mate preferences and intrasexual competition, we investigated male-male competition and behavioral isolation in simulated secondary contact among allopatric populations. Three allopatric color morphs of the cichlid fish Tropheus were tested against each other. Dyadic male-male contests revealed dominance of red males over bluish and yellow-blotch males. Reproductive isolation in the presence of male-male competition was assessed from genetic parentage in experimental ponds and was highly asymmetric among pairs of color morphs. Red females mated only with red males, whereas the other females performed variable degrees of heteromorphic mating. Discrepancies between mating patterns in ponds and female preferences in a competition-free, two-way choice paradigm suggested that the dominance of red males interfered with positive assortative mating of females of the subordinate morphs and provoked asymmetric hybridization. Between the nonred morphs, a significant excess of negative assortative mating by yellow-blotch females with bluish males did not coincide with asymmetric dominance among males. Hence, both negative assortative mating preferences and interference of male-male competition with positive assortative preferences forestall premating isolation, the latter especially in environments unsupportive of competition-driven spatial segregation.

  6. Method development of damage detection in asymmetric buildings

    Science.gov (United States)

    Wang, Yi; Thambiratnam, David P.; Chan, Tommy H. T.; Nguyen, Andy

    2018-01-01

    Aesthetics and functionality requirements have caused most buildings to be asymmetric in recent times. Such buildings exhibit complex vibration characteristics under dynamic loads as there is coupling between the lateral and torsional components of vibration, and are referred to as torsionally coupled buildings. These buildings require three dimensional modelling and analysis. In spite of much recent research and some successful applications of vibration based damage detection methods to civil structures in recent years, the applications to asymmetric buildings has been a challenging task for structural engineers. There has been relatively little research on detecting and locating damage specific to torsionally coupled asymmetric buildings. This paper aims to compare the difference in vibration behaviour between symmetric and asymmetric buildings and then use the vibration characteristics for predicting damage in them. The need for developing a special method to detect damage in asymmetric buildings thus becomes evident. Towards this end, this paper modifies the traditional modal strain energy based damage index by decomposing the mode shapes into their lateral and vertical components and to form component specific damage indices. The improved approach is then developed by combining the modified strain energy based damage indices with the modal flexibility method which was modified to suit three dimensional structures to form a new damage indicator. The procedure is illustrated through numerical studies conducted on three dimensional five-story symmetric and asymmetric frame structures with the same layout, after validating the modelling techniques through experimental testing of a laboratory scale asymmetric building model. Vibration parameters obtained from finite element analysis of the intact and damaged building models are then applied into the proposed algorithms for detecting and locating the single and multiple damages in these buildings. The results

  7. Traveling-wave photodetector

    Science.gov (United States)

    Hietala, V.M.; Vawter, G.A.

    1993-12-14

    The traveling-wave photodetector of the present invention combines an absorptive optical waveguide and an electrical transmission line, in which optical absorption in the waveguide results in a photocurrent at the electrodes of the electrical transmission line. The optical waveguide and electrical transmission line of the electrically distributed traveling-wave photodetector are designed to achieve matched velocities between the light in the optical waveguide and electrical signal generated on the transmission line. This velocity synchronization provides the traveling-wave photodetector with a large electrical bandwidth and a high quantum efficiency, because of the effective extended volume for optical absorption. The traveling-wave photodetector also provides large power dissipation, because of its large physical size. 4 figures.

  8. A cross-sectional study of pre-travel health-seeking practices among travelers departing Sydney and Bangkok airports.

    Science.gov (United States)

    Heywood, Anita E; Watkins, Rochelle E; Iamsirithaworn, Sopon; Nilvarangkul, Kessarawan; MacIntyre, C Raina

    2012-05-02

    Pre-travel health assessments aim to promote risk reduction through preventive measures and safe behavior, including ensuring travelers are up-to-date with their immunizations. However, studies assessing pre-travel health-seeking practices from a variety of medical and non-medical sources and vaccine uptake prior to travel to both developing and developed countries within the Asia-Pacific region are scarce. Cross-sectional surveys were conducted between July and December 2007 to assess pre-travel health seeking practices, including advice from health professionals, health information from other sources and vaccine uptake, in a sample of travelers departing Sydney and Bangkok airports. A two-stage cluster sampling technique was used to ensure representativeness of travelers and travel destinations. Pre-travel health seeking practices were assessed using a self-administered questionnaire distributed at the check-in queues of departing flights. Logistic regression models were used to identify significant factors associated with seeking pre-travel health advice from a health professional, reported separately for Australian residents, residents of other Western countries and residents of countries in Asia. A total of 843 surveys were included in the final sample (Sydney 729, response rate 56%; Bangkok 114, response rate 60%). Overall, pre-travel health information from any source was sought by 415 (49%) respondents with 298 (35%) seeking pre-travel advice from a health professional, the majority through general practice. Receipt of a pre-travel vaccine was reported by 100 (12%) respondents. Significant factors associated with seeking pre-travel health advice from a health professional differed by region of residence. Asian travelers were less likely to report seeking pre-travel health advice and uptake of pre-travel vaccines than Australian or other Western travelers. Migrant Australians were less likely to report seeking pre-travel health advice than Australian

  9. A cross-sectional study of pre-travel health-seeking practices among travelers departing Sydney and Bangkok airports

    Science.gov (United States)

    2012-01-01

    Background Pre-travel health assessments aim to promote risk reduction through preventive measures and safe behavior, including ensuring travelers are up-to-date with their immunizations. However, studies assessing pre-travel health-seeking practices from a variety of medical and non-medical sources and vaccine uptake prior to travel to both developing and developed countries within the Asia-Pacific region are scarce. Methods Cross-sectional surveys were conducted between July and December 2007 to assess pre-travel health seeking practices, including advice from health professionals, health information from other sources and vaccine uptake, in a sample of travelers departing Sydney and Bangkok airports. A two-stage cluster sampling technique was used to ensure representativeness of travelers and travel destinations. Pre-travel health seeking practices were assessed using a self-administered questionnaire distributed at the check-in queues of departing flights. Logistic regression models were used to identify significant factors associated with seeking pre-travel health advice from a health professional, reported separately for Australian residents, residents of other Western countries and residents of countries in Asia. Results A total of 843 surveys were included in the final sample (Sydney 729, response rate 56%; Bangkok 114, response rate 60%). Overall, pre-travel health information from any source was sought by 415 (49%) respondents with 298 (35%) seeking pre-travel advice from a health professional, the majority through general practice. Receipt of a pre-travel vaccine was reported by 100 (12%) respondents. Significant factors associated with seeking pre-travel health advice from a health professional differed by region of residence. Asian travelers were less likely to report seeking pre-travel health advice and uptake of pre-travel vaccines than Australian or other Western travelers. Migrant Australians were less likely to report seeking pre-travel health

  10. Traveling wave laser system

    International Nuclear Information System (INIS)

    Gregg, D.W.; Kidder, R.E.; Biehl, A.T.

    1975-01-01

    The invention broadly involves a method and means for generating a traveling wave laser pulse and is basically analogous to a single pass light amplifier system. However, the invention provides a traveling wave laser pulse of almost unlimited energy content, wherein a gain medium is pumped in a traveling wave mode, the traveling wave moving at essentially the velocity of light to generate an amplifying region or zone which moves through the medium at the velocity of light in the presence of directed stimulating radiation, thereby generating a traveling coherent, directed radiation pulse moving with the amplification zone through the gain medium. (U.S.)

  11. Asymmetric Synthesis via Chiral Aziridines

    DEFF Research Database (Denmark)

    Tanner, David Ackland; Harden, Adrian; Wyatt, Paul

    1996-01-01

    A series of chiral bis(aziridines) has been synthesised and evaluated as chelating ligands for a variety of asymmetric transformations mediated by metals [Os (dihydroxylation), Pd (allylic alkylation) Cu (cyclopropanation and aziridination, Li (1,2-addition of organolithiums to imines)]. In the b......A series of chiral bis(aziridines) has been synthesised and evaluated as chelating ligands for a variety of asymmetric transformations mediated by metals [Os (dihydroxylation), Pd (allylic alkylation) Cu (cyclopropanation and aziridination, Li (1,2-addition of organolithiums to imines...

  12. Optimal multicopy asymmetric Gaussian cloning of coherent states

    International Nuclear Information System (INIS)

    Fiurasek, Jaromir; Cerf, Nicolas J.

    2007-01-01

    We investigate the asymmetric Gaussian cloning of coherent states which produces M copies from N input replicas in such a way that the fidelity of each copy may be different. We show that the optimal asymmetric Gaussian cloning can be performed with a single phase-insensitive amplifier and an array of beam splitters. We obtain a simple analytical expression characterizing the set of optimal asymmetric Gaussian cloning machines and prove the optimality of these cloners using the formalism of Gaussian completely positive maps and semidefinite programming techniques. We also present an alternative implementation of the asymmetric cloning machine where the phase-insensitive amplifier is replaced with a beam splitter, heterodyne detector, and feedforward

  13. Optimal multicopy asymmetric Gaussian cloning of coherent states

    Science.gov (United States)

    Fiurášek, Jaromír; Cerf, Nicolas J.

    2007-05-01

    We investigate the asymmetric Gaussian cloning of coherent states which produces M copies from N input replicas in such a way that the fidelity of each copy may be different. We show that the optimal asymmetric Gaussian cloning can be performed with a single phase-insensitive amplifier and an array of beam splitters. We obtain a simple analytical expression characterizing the set of optimal asymmetric Gaussian cloning machines and prove the optimality of these cloners using the formalism of Gaussian completely positive maps and semidefinite programming techniques. We also present an alternative implementation of the asymmetric cloning machine where the phase-insensitive amplifier is replaced with a beam splitter, heterodyne detector, and feedforward.

  14. Mind your travel ! Motivation, time use, and intent : Three factors of travel to be investigated

    OpenAIRE

    PAPON , Francis; Meissonnier , Joël

    2013-01-01

    The objective is to investigate the drivers of travel demand beyond the need to travel to destination; travellers may engage a trip for the sake of it, at least to some extent: travel includes a share of 'primary utility'. The paper focuses on two types of data and analysis: the primary utility of travel questions passed in the last French national travel survey, and eight dimensions of a trip proposed from a sociological analysis. The paper mixes these approaches and correlate survey answ...

  15. A travel clinic in your office: grow your practice and protect international travelers.

    Science.gov (United States)

    Kirsch, Michael

    2009-01-01

    Medical practices today face economic challenges from declining reimbursements and rising overhead costs. Physicians need to develop new income sources to invigorate their practices and remain viable. Travel medicine-advising and immunizing international travelers-is a rapidly growing specialty in the United States that generates substantial cash reimbursements and professional satisfaction. Travel Clinics of America, a physician-operated company, specializes in helping physicians to incorporate travel medicine into their existing practices.

  16. Health hazards of international travel.

    Science.gov (United States)

    Cossar, J H; Reid, D

    1989-01-01

    The growth of travel and the increasing numbers of those affected by travel-related illnesses, some of a serious nature, will cause this subject to demand the attention of the medical profession, the travel trade, travellers themselves and the health authorities of countries receiving tourists. Provision of appropriate advice for the traveller is a shared responsibility, best channelled mainly through travel agencies; it can moreover be shown to be cost-beneficial. Continued monitoring of illness in travellers and provision of information systems geared to this problem and its prevention are fully justified. They should be based on traditional channels of communication and currently-available modern technology, and be readily accessible to medical and related workers. Increased collaboration between medical workers, health educators and those involved in the travel trade would be a positive and useful contribution towards the reduction of illness and discomfort among travellers and the associated expense incurred by the various national health services concerned. There are clearly economic benefits from the development of international tourism, but these have to be balanced in countries accepting tourists by attention to the prevention of illnesses associated with travel.

  17. Travel medicine and mHealth technology: a study using smartphones to collect health data during travel.

    Science.gov (United States)

    Farnham, Andrea; Blanke, Ulf; Stone, Emily; Puhan, Milo A; Hatz, Christoph

    2016-06-01

    mHealth methodology such as smartphone applications offers new opportunities to capture the full range of health risks during travel in real time. Our study aims to widen the scope of travel health research in tropical and subtropical destinations by using a smartphone application to collect detailed information on health behaviours, clinical symptoms, accidents and environmental factors during travel. We enrolled travel clinic clients in Zurich and Basel ≥18 years of age travelling to Thailand for travel. Participants were equipped with a smartphone and an application that (1) actively administers a daily self-report questionnaire on the health risks, behaviours and symptoms the traveller encountered, and (2) passively collects information on the traveller's location and environmental conditions by transformation of raw GPS data. A prospective cohort of 101 travellers planning travel to Thailand between January and June 2015 was recruited. Of the 101 enrolled travellers, 75 (74.3%) answered at least one questionnaire during travel, 10 (9.9%) had technical difficulties and 16 (15.8%) dropped out. Those who completed questionnaires were a median of 27.0 years old (range 18-57). Travellers filled out a median of 12.0 questionnaires during their trip (range 1-30), corresponding to a median completion rate of 85.0% days of travel. The typical example of a healthy female traveller shows that many and diverse health issues arise during a trip that clusters on certain days. The rich data on behaviour and local environment may be used to explain the occurrence and clustering of health issues. Use of a smartphone app to collect health information is technically feasible and acceptable amongst a traveller population, minimizes recall bias and greatly increases the quality and quantity of data collected during travel. mHealth technology shows great potential for innovation in travel medicine. © International Society of Travel Medicine, 2016. All rights reserved

  18. Knowledge Representation in Travelling Texts

    DEFF Research Database (Denmark)

    Mousten, Birthe; Locmele, Gunta

    2014-01-01

    Today, information travels fast. Texts travel, too. In a corporate context, the question is how to manage which knowledge elements should travel to a new language area or market and in which form? The decision to let knowledge elements travel or not travel highly depends on the limitation...... and the purpose of the text in a new context as well as on predefined parameters for text travel. For texts used in marketing and in technology, the question is whether culture-bound knowledge representation should be domesticated or kept as foreign elements, or should be mirrored or moulded—or should not travel...... at all! When should semantic and pragmatic elements in a text be replaced and by which other elements? The empirical basis of our work is marketing and technical texts in English, which travel into the Latvian and Danish markets, respectively....

  19. 76 FR 43236 - Federal Travel Regulation (FTR): Temporary Duty (TDY) Travel Allowances: Notice of Public Meeting

    Science.gov (United States)

    2011-07-20

    ...; Sequence 5] Federal Travel Regulation (FTR): Temporary Duty (TDY) Travel Allowances: Notice of Public... public meeting. SUMMARY: The General Services Administration (GSA) is revising the Federal Travel Regulation (FTR) in an effort to streamline travel policies, increase travel efficiency and effectiveness...

  20. Travel, infection and immunity

    OpenAIRE

    Soonawala, Darius

    2016-01-01

    Preface: The content of this thesis is based on research that was conducted at the travel and vaccination clinic at Leiden University Medical Centre (LUMC). This clinic provides pre-travel care to the general population, and to special groups of travellers, such as patients who use immunosuppressants or who have chronic diseases. The clinic is closely connected to the department of Infectious Diseases at LUMC. The setting of a travel clinic within an academic medical hospital, provides unique...

  1. Survey of beta-particle interaction experiments with asymmetric matter

    Science.gov (United States)

    Van Horn, J. David; Wu, Fei

    2018-05-01

    Asymmetry is a basic property found at multiple scales in the universe. Asymmetric molecular interactions are fundamental to the operation of biological systems in both signaling and structural roles. Other aspects of asymmetry are observed and useful in many areas of science and engineering, and have been studied since the discovery of chirality in tartrate salts. The observation of parity violation in beta decay provided some impetus for later experiments using asymmetric particles. Here we survey historical work and experiments related to electron (e-) or positron (e+) polarimetry and their interactions with asymmetric materials in gas, liquid and solid forms. Asymmetric interactions may be classified as: 1) stereorecognition, 2) stereoselection and 3) stereoinduction. These three facets of physical stereochemistry are unique but interrelated; and examples from chemistry and materials science illustrate these aspects. Experimental positron and electron interactions with asymmetric materials may be classified in like manner. Thus, a qualitative assessment of helical and polarized positron experiments with different forms of asymmetric matter from the past 40 years is presented, as well as recent experiments with left-hand and right-hand single crystal quartz and organic compounds. The purpose of this classification and review is to evaluate the field for potential new experiments and directions for positron (or electron) studies with asymmetric materials.

  2. Exploring disagreement prevention and resolution in travel decision-making of young Chinese travellers

    OpenAIRE

    Song, Hanqun; Sparks, Beverley; Wang, Ying

    2017-01-01

    The young Chinese travel market is becoming increasingly significant in domestic and international tourism. However, there is limited research on the market. This study examines the decision-making processes of young Chinese travellers, with a particular interest in disagreement prevention and resolution. On the basis of interviews with 25 young Chinese travellers, this study found that while a small number of travellers did not perceive any disagreement, or did not voice their disagreement, ...

  3. Travel advice for the immunocompromised traveler: prophylaxis, vaccination, and other preventive measures

    Directory of Open Access Journals (Sweden)

    Patel RR

    2015-02-01

    Full Text Available Rupa R Patel,1 Stephen Y Liang,1 Pooja Koolwal,2 Frederick Matthew Kuhlmann1 1Division of Infectious Diseases, 2Division of Medical Education, Washington University School of Medicine, St Louis, MO, USA Abstract: Immunocompromised patients are traveling at increasing rates. Physicians caring for these complex patients must be knowledgeable in pretravel consultation and recognize when referral to an infectious disease specialist is warranted. This article outlines disease prevention associated with international travel for adults with human immunodeficiency virus, asplenia, solid organ and hematopoietic transplantation, and other immunosuppressed states. While rates of infection may not differ significantly between healthy and immunocompromised travelers, the latter are at greater risk for severe disease. A thorough assessment of these risks can ensure safe and healthy travel. The travel practitioners’ goal should be to provide comprehensive risk information and recommend appropriate vaccinations or prevention measures tailored to each patient’s condition. In some instances, live vaccines and prophylactic medications may be contraindicated. Keywords: immunocompromised, vaccines, travel, malaria, diarrhea

  4. Travel Characteristics and Pretravel Health Care Among Pregnant or Breastfeeding U.S. Women Preparing for International Travel.

    Science.gov (United States)

    Hagmann, Stefan H F; Rao, Sowmya R; LaRocque, Regina C; Erskine, Stefanie; Jentes, Emily S; Walker, Allison T; Barnett, Elizabeth D; Chen, Lin H; Hamer, Davidson H; Ryan, Edward T

    2017-12-01

    To study characteristics and preventive interventions of adult pregnant and breastfeeding travelers seeking pretravel health care in the United States. This cross-sectional study analyzed data (2009-2014) of pregnant and breastfeeding travelers seen at U.S. travel clinics participating in Global TravEpiNet. Nonpregnant, nonbreastfeeding adult female travelers of childbearing age were used for comparison. We evaluated the prescription of malaria chemoprophylaxis and antibiotics for this population as well as the administration of three travel-related vaccines: hepatitis A, typhoid, and yellow fever. We also evaluated use of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis and influenza vaccines, because these are widely recommended in pregnancy. Of 21,138 female travelers of childbearing age in Global TravEpiNet, 170 (0.8%) were pregnant and 139 (0.7%) were breastfeeding. Many traveled to destinations endemic for mosquito-borne illnesses, including malaria (pregnant: 95%; breastfeeding: 94%), dengue (pregnant: 87%; breastfeeding: 81%), or yellow fever (pregnant: 35%; breastfeeding: 50%). Compared with nonpregnant, nonbreastfeeding adult female travelers, eligible pregnant travelers were less likely to be vaccinated against hepatitis A (28% compared with 51%, Ptravelers did not receive influenza vaccination. Yellow fever vaccine was occasionally provided to pregnant and breastfeeding travelers traveling to countries entirely endemic for yellow fever (6 [20%] of 30 pregnant travelers and 18 [46%] of 39 breastfeeding travelers). Half of pregnant travelers and two thirds of breastfeeding travelers preparing to travel to malaria-holoendemic countries received a prescription for malaria prophylaxis. Most pregnant and breastfeeding travelers seen for pretravel health consultations traveled to destinations with high risk for vector-borne or other travel-related diseases. Destination-specific preventive interventions were frequently underused.

  5. The value of travel time variance

    DEFF Research Database (Denmark)

    Fosgerau, Mogens; Engelson, Leonid

    2011-01-01

    This paper considers the value of travel time variability under scheduling preferences that are defined in terms of linearly time varying utility rates associated with being at the origin and at the destination. The main result is a simple expression for the value of travel time variability...... that does not depend on the shape of the travel time distribution. The related measure of travel time variability is the variance of travel time. These conclusions apply equally to travellers who can freely choose departure time and to travellers who use a scheduled service with fixed headway. Depending...... on parameters, travellers may be risk averse or risk seeking and the value of travel time may increase or decrease in the mean travel time....

  6. 76 FR 46216 - Federal Travel Regulation (FTR): Temporary Duty (TDY) Travel Allowances: Notice of Public Meeting...

    Science.gov (United States)

    2011-08-02

    ...; Sequence 5] Federal Travel Regulation (FTR): Temporary Duty (TDY) Travel Allowances: Notice of Public... and the general public in an effort to streamline travel policies, incorporated travel efficiency and.... Flynn, Deputy Director, Office of Travel, Transportation & Asset Management. [FR Doc. 2011-19482 Filed 8...

  7. Costs of travel time uncertainty and benefits of travel time information: Conceptual model and numerical examples

    NARCIS (Netherlands)

    Ettema, D.F.; Timmermans, H.J.P.

    2006-01-01

    A negative effect of congestion that tends to be overlooked is travel time uncertainty. Travel time uncertainty causes scheduling costs due to early or late arrival. The negative effects of travel time uncertainty can be reduced by providing travellers with travel time information, which improves

  8. Traveling wave laser system

    International Nuclear Information System (INIS)

    Gregg, D.W.; Kidder, R.E.; Biehl, A.T.

    1975-01-01

    A method is described for generating a traveling wave laser pulse of almost unlimited energy content wherein a gain medium is pumped into a traveling wave mode, the traveling wave moving at essentially the velocity of light to generate an amplifying region or zone which moves through the medium at the velocity of light in the presence of directed stimulating radiation, thereby generating a traveling coherent, directed radiation pulse moving with the amplification zone through the gain medium. (U.S.)

  9. Evaluation of Edge Assembly Crossover for Hybrid GA

    OpenAIRE

    Yoshihara, Ikuo; Sato, Masakazu; Nguyen, Hung Dinh; Yamanori, Kunihito

    2004-01-01

    Abstract ###Traveling Salesman Problem (TSP) is one of the representative combinatorial optimization prob-###lems. The promising approach to solve TSP is Genetic Algorithm (GA). GA has global search ability, ###and heuristic is used in order to compensate local search ability, because GA is lack of local search abil-###ity. Hybrid (GA (HGA) combined with heuristics can be expected to obtain high quality solutions.We ###employ Lin-Kernighan heuristics which is very effective in TSP. Because cr...

  10. An integrated TSP-GA with EOL cost model for selecting the best EOL option

    OpenAIRE

    Zakri Ghazalli; Atsuo Murata

    2011-01-01

    This paper presents our research works on integrating design for disassembly with cost model for end-of-life (EOL) product. This paper has two objectives. The first objective is to optimize disassembly sequence of the EOL product. We integrate a traveling salesman problem approach with genetic algorithm in finding the optimal disassembly sequence for disassembling the EOL product. Based on this optimal sequence, the second objective is to identify the best EOL option. We employ EOL profits an...

  11. PALNS - A software framework for parallel large neighborhood search

    DEFF Research Database (Denmark)

    Røpke, Stefan

    2009-01-01

    This paper propose a simple, parallel, portable software framework for the metaheuristic named large neighborhood search (LNS). The aim is to provide a framework where the user has to set up a few data structures and implement a few functions and then the framework provides a metaheuristic where ...... parallelization "comes for free". We apply the parallel LNS heuristic to two different problems: the traveling salesman problem with pickup and delivery (TSPPD) and the capacitated vehicle routing problem (CVRP)....

  12. Effect of self-deflection on a totally asymmetric simple exclusion process with functions of site assignments

    Science.gov (United States)

    Tsuzuki, Satori; Yanagisawa, Daichi; Nishinari, Katsuhiro

    2018-04-01

    This study proposes a model of a totally asymmetric simple exclusion process on a single-channel lane with functions of site assignments along the pit lane. The system model attempts to insert a new particle to the leftmost site at a certain probability by randomly selecting one of the empty sites in the pit lane, and reserving it for the particle. Thereafter, the particle is directed to stop at the site only once during its travel. Recently, the system was determined to show a self-deflection effect, in which the site usage distribution biases spontaneously toward the leftmost site, and the throughput becomes maximum when the site usage distribution is slightly biased to the rightmost site. Our exact analysis describes this deflection effect and show a good agreement with simulations.

  13. Travel, infection and immunity

    NARCIS (Netherlands)

    Soonawala, Darius

    2016-01-01

    Preface: The content of this thesis is based on research that was conducted at the travel and vaccination clinic at Leiden University Medical Centre (LUMC). This clinic provides pre-travel care to the general population, and to special groups of travellers, such as patients who use

  14. Modelling urban travel times

    NARCIS (Netherlands)

    Zheng, F.

    2011-01-01

    Urban travel times are intrinsically uncertain due to a lot of stochastic characteristics of traffic, especially at signalized intersections. A single travel time does not have much meaning and is not informative to drivers or traffic managers. The range of travel times is large such that certain

  15. Travelers' Health: Trypanosomiasis, American (Chagas Disease)

    Science.gov (United States)

    ... Stamaril clinics Disease Directory Resources Resources for Travelers Adventure Travel Animal Safety Blood Clots Bug Bites Evite ... Minute Travel Long-Term Travel Mass Gatherings Medical Tourism Mental Health Motion Sickness Natural Disasters Pregnant Travelers ...

  16. TRAVEL AND HOME LEAVE

    CERN Multimedia

    Human Resources Division

    2002-01-01

    Administrative procedures for : Travel to the home station and home leave (hl) Additional travel to the home station (at) Travel to the home station and home leave for family reasons (hlf) As part of the process of simplifying administrative procedures, HR and AS Divisions have devised a new, virtually automatic procedure for payment of travel expenses to the home station. The changes are aimed at rationalising administrative procedures and not at reducing benefits. The conditions of eligibility are unchanged. The new procedure, which will be operational with effect from 1st June 2002, will greatly simplify the administrative processing of claims for travel expenses and the recording of home leaves. Currently, requests for payment are introduced manually into the Advances and Claims system (AVCL) by divisional secretariats. All travel to the home station starting prior to 1st June 2002 will be processed according to the existing system whereas that starting on 1st June and after will be processed accordi...

  17. Residential self-selection and travel : The relationship between travel-related attitudes, built environment characteristics and travel behaviour

    NARCIS (Netherlands)

    Bohte, W.

    2010-01-01

    Most Western national governments aim to influence individual travel patterns – at least to some degree – through spatial planning in residential areas. Nevertheless, the extent to which the characteristics of the built environment influence travel behaviour remains the subject of some debate among

  18. Writing Travel in the Anthropocene

    DEFF Research Database (Denmark)

    Graulund, Rune

    2016-01-01

    the Anthropocene - which is to say an age in which nowhere, not the furthest reachest of the stratosphere nor the lowest point in the marine abyss, are untouched by the activities and detritus of humankind. The essay will give a short overview of the manner in which the notion of 'travel' has been contested......Travel writing critics have proclaimed the end of travel since at least the beginning of the 20th Century. Yet the global age of the 21st century presents us with a range a problems that challenge the notion of travel in manners that neither travellers, travel writers, nor travel writing critics...... could have imagined just a century ago. Globalisation and increased mobility, whether it is that of the privileged few who can travel on holiday on jet airplanes, or that of the immigrant labourer seeking employment by crossing borders on foot, have meant millions (if not indeed billions) are constantly...

  19. Time-Dependent-Asymmetric-Linear-Parsimonious Ancestral State Reconstruction.

    Science.gov (United States)

    Didier, Gilles

    2017-10-01

    The time-dependent-asymmetric-linear parsimony is an ancestral state reconstruction method which extends the standard linear parsimony (a.k.a. Wagner parsimony) approach by taking into account both branch lengths and asymmetric evolutionary costs for reconstructing quantitative characters (asymmetric costs amount to assuming an evolutionary trend toward the direction with the lowest cost). A formal study of the influence of the asymmetry parameter shows that the time-dependent-asymmetric-linear parsimony infers states which are all taken among the known states, except for some degenerate cases corresponding to special values of the asymmetry parameter. This remarkable property holds in particular for the Wagner parsimony. This study leads to a polynomial algorithm which determines, and provides a compact representation of, the parametric reconstruction of a phylogenetic tree, that is for all the unknown nodes, the set of all the possible reconstructed states associated with the asymmetry parameters leading to them. The time-dependent-asymmetric-linear parsimony is finally illustrated with the parametric reconstruction of the body size of cetaceans.

  20. Information impact on quality of travel choices: analysis of data from a multimodal travel simulator

    NARCIS (Netherlands)

    Chorus, C.G.; Arentze, T.A.; Timmermans, H.J.P.; Silva, da A.N.R.; Souza, de L.C.L.

    2007-01-01

    This paper investigates the impact of travel information on the quality of travel choices. It distinguishes itself from earlier studies on this topic by empirically investigating the impact of a variety of travel information types on the quality of observed multimodal travel choices. Choice quality

  1. Drug use, travel and HIV risk.

    Science.gov (United States)

    Lee, D; Bell, D C; Hinojosa, M

    2002-08-01

    A study was conducted to examine the travel experiences of a community sample of 160 drug users and 44 non-users recruited as part of a study of HIV risk. Of the sample, 47% (96/204) reported intercity travel in the previous ten years. Results showed that men were more likely to travel than women, Anglos more than minorities, and young persons more than old. When travellers testing HIV-seropositive (n = 13) were compared with seronegative travellers, HIV-positive travellers reported more sex while travelling than HIV-negative persons, but virtually all of the difference reported involved sex with condoms. There were no significant differences in sex risk behaviours while travelling between drug users and non-drug users, or in sex risk behaviors between drug injectors and non-injectors. Travellers had fewer injection partners while travelling than they had while at home. There was also a significant difference in number of sex partners with whom a condom was not used, with fewer sex partners while travelling.

  2. Mechanochemistry assisted asymmetric organocatalysis: A sustainable approach

    Directory of Open Access Journals (Sweden)

    Pankaj Chauhan

    2012-12-01

    Full Text Available Ball-milling and pestle and mortar grinding have emerged as powerful methods for the development of environmentally benign chemical transformations. Recently, the use of these mechanochemical techniques in asymmetric organocatalysis has increased. This review highlights the progress in asymmetric organocatalytic reactions assisted by mechanochemical techniques.

  3. Asymmetric strand segregation: epigenetic costs of genetic fidelity?

    Directory of Open Access Journals (Sweden)

    Diane P Genereux

    2009-06-01

    Full Text Available Asymmetric strand segregation has been proposed as a mechanism to minimize effective mutation rates in epithelial tissues. Under asymmetric strand segregation, the double-stranded molecule that contains the oldest DNA strand is preferentially targeted to the somatic stem cell after each round of DNA replication. This oldest DNA strand is expected to have fewer errors than younger strands because some of the errors that arise on daughter strands during their synthesis fail to be repaired. Empirical findings suggest the possibility of asymmetric strand segregation in a subset of mammalian cell lineages, indicating that it may indeed function to increase genetic fidelity. However, the implications of asymmetric strand segregation for the fidelity of epigenetic information remain unexplored. Here, I explore the impact of strand-segregation dynamics on epigenetic fidelity using a mathematical-modelling approach that draws on the known molecular mechanisms of DNA methylation and existing rate estimates from empirical methylation data. I find that, for a wide range of starting methylation densities, asymmetric -- but not symmetric -- strand segregation leads to systematic increases in methylation levels if parent strands are subject to de novo methylation events. I found that epigenetic fidelity can be compromised when enhanced genetic fidelity is achieved through asymmetric strand segregation. Strand segregation dynamics could thus explain the increased DNA methylation densities that are observed in structured cellular populations during aging and in disease.

  4. Ideal 3D asymmetric concentrator

    Energy Technology Data Exchange (ETDEWEB)

    Garcia-Botella, Angel [Departamento Fisica Aplicada a los Recursos Naturales, Universidad Politecnica de Madrid, E.T.S.I. de Montes, Ciudad Universitaria s/n, 28040 Madrid (Spain); Fernandez-Balbuena, Antonio Alvarez; Vazquez, Daniel; Bernabeu, Eusebio [Departamento de Optica, Universidad Complutense de Madrid, Fac. CC. Fisicas, Ciudad Universitaria s/n, 28040 Madrid (Spain)

    2009-01-15

    Nonimaging optics is a field devoted to the design of optical components for applications such as solar concentration or illumination. In this field, many different techniques have been used for producing reflective and refractive optical devices, including reverse engineering techniques. In this paper we apply photometric field theory and elliptic ray bundles method to study 3D asymmetric - without rotational or translational symmetry - concentrators, which can be useful components for nontracking solar applications. We study the one-sheet hyperbolic concentrator and we demonstrate its behaviour as ideal 3D asymmetric concentrator. (author)

  5. Carlson Wagonlit Travel

    CERN Multimedia

    Carlson Wagonlit Travel

    2005-01-01

    Dear customers, On 3 January we informed you that the airlines had decided to cease paying commission to travel agencies in Switzerland. This measure has since been progressively introduced, with rare exceptions. Consequently, in agreement with CERN, we are obliged to apply new transaction fees for private travel, with immediate effect. Carlson Wagonlit Travel (CWT) offers: A personalized, professional and competent consultancy service To seek the most economical and best solution adapted to your needs Neutrality in comparing prices and benefits Additional information concerning e.g. visa regulations, insurance, vaccinations, etc. Support in the event of problems We draw your attention to the fact that, in spite of the increase, these prices remain very competitive on today's market. Thank you for your trust and understanding. Yours truly, Carlson Wagonlit Travel CERN agency

  6. Hepatitis B vaccination in travelers

    NARCIS (Netherlands)

    Sonder, Gerard J. B.

    2008-01-01

    An increasing number of travelers travel to hepatitis B-endemic countries. In travel medicine, vaccinations should be advised according to risks. The actual incidence of hepatitis B infection in short-term tourists is very low and probably not higher than it is for people who do not travel. There is

  7. Trends and characteristics among HIV-infected and diabetic travelers seeking pre-travel advice

    NARCIS (Netherlands)

    Elfrink, Floor; van den Hoek, Anneke; Sonder, Gerard J. B.

    2014-01-01

    The number of individuals with a chronic disease increases. Better treatment options have improved chronic patients' quality of life, likely increasing their motivation for travel. This may have resulted in a change in the number of HIV-infected travelers and/or travelers with Diabetes Mellitus (DM)

  8. Effectiveness of pre-travel consultation in the prevention of travel-related diseases: a retrospective cohort study.

    Science.gov (United States)

    Tafuri, Silvio; Guerra, Rocco; Gallone, Maria Serena; Cappelli, Maria Giovanna; Lanotte, Serafina; Quarto, Michele; Germinario, Cinzia

    2014-01-01

    This study aims to evaluate the effectiveness of pre-travel counselling carried out in Travel Clinics. This is a retrospective cohort. Three hundred international travellers were enrolled; 150 people were from users of Bari Travel Clinic, 150 were users of a travel agency. Enrolled subjects were interviewed using a questionnaire. The average age of the enrolled subjects was 37.5 ± 13.9, without statistically significant differences between the two groups. 86% of cases and 19.3% of the controls reported the use of anti-malaria prophylaxis (p Travel Clinic users, 6% reported diarrhoea and these figures were 27% in the control group (p study demonstrated the effectiveness of pre-travel counselling; in the future, new studies must investigate the cost-effectiveness of pre-travel prevention measures.

  9. Risk factors for infections in international travelers: an analysis of travel-related notifiable communicable diseases.

    Science.gov (United States)

    Baer, Atar; Libassi, Lisa; Lloyd, Jennifer K; Benoliel, Eileen; Brucker, Rachel; Jones, Megan Q; Kwan-Gett, Tao Sheng; McKeirnan, Shelly; Pecha, Monica; Rietberg, Krista; Serafin, Lauri; Walkinshaw, Lina P; Duchin, Jeffrey S

    2014-01-01

    We sought to describe travel-related illness among our residents and gain insight into targeting pre-travel health advice to prevent travel-related illness. A supplemental travel questionnaire was developed and administered for cases with a legally notifiable communicable disease reported in 2011-2012, who spent at least part of their exposure period outside the United States. Among 451 cases meeting the eligibility criteria, 259 were interviewed. Forty four percent reported receiving pre-travel advice. Two-thirds adhered fully with risk behavior recommendations; 94% followed immunization recommendations partially or fully; and 84% adhered fully with malaria prophylaxis recommendations. The primary reasons for not obtaining pre-travel advice were being unaware of the need (47.5%), or believing they already knew what to do (34.5%). Adults (OR = 2.8, 95% CI = 1.4-5.5), males (OR = 1.8, 95% CI = 1.1-3.0), those born outside the United States (OR = 2.0, 95% CI = 1.1-3.7), and those with planning time under two weeks (OR = 4.8, 95% CI = 1.5-15.9) or travel duration less than 7 days (OR = 7.9, 95% CI = 3.0-20.9) were more likely to travel without seeking pre-travel advice. The majority of cases reported not receiving pre-travel advice. Understanding the predictors of failure to receive pre-travel advice may help target public health prevention efforts. Copyright © 2014 Elsevier Ltd. All rights reserved.

  10. Health challenges of young travelers visiting friends and relatives compared with those traveling for other purposes.

    Science.gov (United States)

    Han, Pauline; Yanni, Emad; Jentes, Emily S; Hamer, Davidson H; Chen, Lin H; Wilson, Mary E; Macleod, William B; Ooi, Winnie W; Kogelman, Laura; Karchmer, Adolf W; Barnett, Elizabeth D

    2012-09-01

    The study objective was to assess differences in demographics and travel health challenges between youths ≤18 years old traveling internationally to visit friends and relatives (VFRs) compared with those traveling for other purposes (non-VFR). The Boston Area Travel Medicine Network consists of 5 clinics collecting anonymous data from international pretravel consultations. Data on all travelers ≤18 years of age seen between January 2008 and July 2010 were used. VFRs were compared with non-VFRs on demographics, primary language, trip characteristics, travel vaccinations administered, malaria prophylaxis and antidiarrheal medications prescribed. Thirty-five percent (610/1731) listed VFR as their purpose of travel. Almost half of VFRs were travel to countries that were yellow fever holoendemic, had malaria risk and were high-risk for typhoid (44% versus 20%, 39% versus 12%, 25% versus 15%, P travel-related morbidity, healthcare providers should be prepared to give travel advice to parents of VFR infants and children, particularly those US-born VFRs with foreign-born parents, regarding antimalarial and antidiarrheal medications and preventing yellow fever, malaria and typhoid.

  11. Travel Time Reliability in Indiana

    OpenAIRE

    Martchouk, Maria; Mannering, Fred L.; Singh, Lakhwinder

    2010-01-01

    Travel time and travel time reliability are important performance measures for assessing traffic condition and extent of congestion on a roadway. This study first uses a floating car technique to assess travel time and travel time reliability on a number of Indiana highways. Then the study goes on to describe the use of Bluetooth technology to collect real travel time data on a freeway and applies it to obtain two weeks of data on Interstate 69 in Indianapolis. An autoregressive model, estima...

  12. Travel risk behaviours and uptake of pre-travel health preventions by university students in Australia.

    Science.gov (United States)

    Heywood, Anita E; Zhang, Meng; MacIntyre, C Raina; Seale, Holly

    2012-02-17

    Forward planning and preventative measures before travelling can significantly reduce the risk of many vaccine preventable travel-related infectious diseases. Higher education students may be at an increased risk of importing infectious disease as many undertake multiple visits to regions with higher infectious disease endemicity. Little is known about the health behaviours of domestic or international university students, particularly students from low resource countries who travel to high-resource countries for education. This study aimed to assess travel-associated health risks and preventative behaviours in a sample of both domestic and international university students in Australia. In 2010, a 28 item self-administered online survey was distributed to students enrolled at the University of New South Wales, Sydney, Australia. Multiple methods of distributing links to the online survey were utilised. The survey examined the international travel history, travel intentions, infection control behaviours and self-reported vaccination history. A total of 1663 respondents completed the online survey, 22.1% were international students and 83.9% were enrolled at an undergraduate level. Half had travelled internationally in the previous 12 months, with 69% of those travelling only once during that time with no difference in travel from Australia between domestic and international students (p = 0.8). Uptake of pre-travel health advice was low overall with 68% of respondents reporting they had not sought any advice from a health professional prior to their last international trip. Domestic students were more likely to report uptake of a range of preventative travel health measures compared to international students, including diarrhoeal medication, insect repellent, food avoidance and condoms (P students reported low risk perception of travel threats and a low corresponding concern for these threats. Our study highlights the need to educate students about the risk

  13. Knowledge, attitudes, and practices evaluation about travel medicine in international travelers and medical students in Chile.

    Science.gov (United States)

    Guerrero-Lillo, Lisette; Medrano-Díaz, Jorge; Pérez, Carmen; Chacón, Rodrigo; Silva-Urra, Juan; Rodriguez-Morales, Alfonso J

    2009-01-01

    Because information about travel medicine in Chile is lacking, a knowledge, attitudes, and practices evaluation in international travelers and medical students was done. The travelers and medical students did not know the travel medicine and sanitary conditions of their destinations, although they perceived travel-associated health risks, but <10% had any vaccination and 5% got sick during international trips.

  14. Traveling and Asthma

    Science.gov (United States)

    ... Videos for Educators Search English Español Traveling and Asthma KidsHealth / For Kids / Traveling and Asthma Print en ... pack it, too. How Can I Avoid My Asthma Triggers? Staying at a hotel Ask for a ...

  15. Asymmetric hindwing foldings in rove beetles.

    Science.gov (United States)

    Saito, Kazuya; Yamamoto, Shuhei; Maruyama, Munetoshi; Okabe, Yoji

    2014-11-18

    Foldable wings of insects are the ultimate deployable structures and have attracted the interest of aerospace engineering scientists as well as entomologists. Rove beetles are known to fold their wings in the most sophisticated ways that have right-left asymmetric patterns. However, the specific folding process and the reason for this asymmetry remain unclear. This study reveals how these asymmetric patterns emerge as a result of the folding process of rove beetles. A high-speed camera was used to reveal the details of the wing-folding movement. The results show that these characteristic asymmetrical patterns emerge as a result of simultaneous folding of overlapped wings. The revealed folding mechanisms can achieve not only highly compact wing storage but also immediate deployment. In addition, the right and left crease patterns are interchangeable, and thus each wing internalizes two crease patterns and can be folded in two different ways. This two-way folding gives freedom of choice for the folding direction to a rove beetle. The use of asymmetric patterns and the capability of two-way folding are unique features not found in artificial structures. These features have great potential to extend the design possibilities for all deployable structures, from space structures to articles of daily use.

  16. Travelling Concepts

    DEFF Research Database (Denmark)

    Simonsen, Karen-Margrethe

    2013-01-01

    Review of "Travelling Concepts, Metaphors, and Narratives: Literary and Cultural Studies in an Age of Interdisciplinary Research" ed. by Sibylle Baumgarten, Beatrice Michaelis and Ansagar Nünning, Trier; Wissenschaftlicher Verlag Trier, 2012......Review of "Travelling Concepts, Metaphors, and Narratives: Literary and Cultural Studies in an Age of Interdisciplinary Research" ed. by Sibylle Baumgarten, Beatrice Michaelis and Ansagar Nünning, Trier; Wissenschaftlicher Verlag Trier, 2012...

  17. Impact of advice given to travelers concerning the main infectious risks associated with traveling in the tropics.

    Science.gov (United States)

    Lestelle, C; Aymeric, S; Maakaroun-Vermesse, Z; Pouliquen, A; Bernard, L; Chandenier, J; Grammatico-Guillon, L

    2015-06-01

    The prevention of sanitary risks related to traveling in the tropics implies delivering a large amount of information to travelers. The objective of our study was to assess the knowledge acquired by travelers during a pre-travel consultation. A before and after study was conducted among 202 travelers having consulted at the Tours international vaccine center. We used self-administrated questionnaires (score out of 100 marks) concerning diet, hygiene, anti-vectorial prevention (AVP), and sexual-transmitted infections (STI). The scores obtained before and after consultation were compared globally and for each topic. The travelers' global knowledge had improved after consultation (66.1 vs. 75.5%; P traveling compared to humanitarian mission prepared ahead of departure time). The recommendations for diet were less well acquired in travelers > 50 years of age than in those travel consultation improves the travelers' knowledge for the main prevention measures but does not allow them to acquire all required knowledge. Taking into account the travelers' initial knowledge and their ability to learn could improve the impact of the pre-travel consultation. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  18. 41 CFR 301-71.105 - Must we issue a written or electronic travel authorization in advance of travel?

    Science.gov (United States)

    2010-07-01

    ... or electronic travel authorization in advance of travel? 301-71.105 Section 301-71.105 Public Contracts and Property Management Federal Travel Regulation System TEMPORARY DUTY (TDY) TRAVEL ALLOWANCES AGENCY RESPONSIBILITIES 71-AGENCY TRAVEL ACCOUNTABILITY REQUIREMENTS Travel Authorization § 301-71.105...

  19. Examining the Relationship between Online Travel Agency Information and Traveler Destination Transaction Decisions

    Science.gov (United States)

    Yerby, Dennis

    2012-01-01

    The purpose of this quantitative study was to examine the role that available Online Travel Agency (OTA) destination information may have on a traveler's perceptions and intent in transaction decisions with that respective OTA. Specifically, this research examined a pleasure traveler's transaction perceptions and intentions with an OTA…

  20. Travel Agent Course Outline.

    Science.gov (United States)

    British Columbia Dept. of Education, Victoria.

    Written for college entry-level travel agent training courses, this course outline can also be used for inservice training programs offered by travel agencies. The outline provides information on the work of a travel agent and gives clear statements on what learners must be able to do by the end of their training. Material is divided into eight…

  1. Travel time variability and rational inattention

    DEFF Research Database (Denmark)

    Fosgerau, Mogens; Jiang, Gege

    2017-01-01

    This paper sets up a rational inattention model for the choice of departure time for a traveler facing random travel time. The traveler chooses how much information to acquire about the travel time out-come before choosing departure time. This reduces the cost of travel time variability compared...

  2. Monitoring Travel Time Reliability on Freeways

    NARCIS (Netherlands)

    Tu, Huizhao

    2008-01-01

    Travel time and travel time reliability are important attributes of a trip. The current measures of reliability have in common that in general they all relate to the variability of travel times. However, travel time reliability does not only rely on variability but also on the stability of travel

  3. Search Problems in Mission Planning and Navigation of Autonomous Aircraft. M.S. Thesis

    Science.gov (United States)

    Krozel, James A.

    1988-01-01

    An architecture for the control of an autonomous aircraft is presented. The architecture is a hierarchical system representing an anthropomorphic breakdown of the control problem into planner, navigator, and pilot systems. The planner system determines high level global plans from overall mission objectives. This abstract mission planning is investigated by focusing on the Traveling Salesman Problem with variations on local and global constraints. Tree search techniques are applied including the breadth first, depth first, and best first algorithms. The minimum-column and row entries for the Traveling Salesman Problem cost matrix provides a powerful heuristic to guide these search techniques. Mission planning subgoals are directed from the planner to the navigator for planning routes in mountainous terrain with threats. Terrain/threat information is abstracted into a graph of possible paths for which graph searches are performed. It is shown that paths can be well represented by a search graph based on the Voronoi diagram of points representing the vertices of mountain boundaries. A comparison of Dijkstra's dynamic programming algorithm and the A* graph search algorithm from artificial intelligence/operations research is performed for several navigation path planning examples. These examples illustrate paths that minimize a combination of distance and exposure to threats. Finally, the pilot system synthesizes the flight trajectory by creating the control commands to fly the aircraft.

  4. Enquiries to the United Kingdom National Travel Advice Line by healthcare professionals regarding immunocompromised travellers.

    Science.gov (United States)

    Allen, Joanna E; Patel, Dipti

    2016-03-01

    People who travel while immunocompromised are more at risk of serious travel-related infection. Their condition, medications or treatments can contraindicate, decrease the effectiveness of or increase the toxicity of vaccinations or malaria chemoprophylaxis. Therefore, immunocompromised travellers require careful assessment and specialized pre-travel advice. The aims of this study were to investigate enquiries by healthcare professionals (HCPs) to the UK National Travel Health Network and Centre (NaTHNaC) advice line regarding travellers with immunocompromise and to identify their most common concerns. Documentation for all calls taken by advisers at the London office during 2013 was reviewed. Of the 4910 enquiries to the London NaTHNaC advice line, 397 calls concerned immunocompromised travellers (8.1%). The majority of immunocompromised travellers were planning to visit Sub-Saharan Africa (53%) for the purpose of tourism (43%). Sixty-seven percent of enquiries concerned vaccine use, 11% were about malaria chemoprophylaxis, 20% were about both and 2% were for other reasons. Causes of immunocompromise included inflammatory or autoimmune conditions (43%), cancer (18%), splenic dysfunction (13%), immunosuppressive drugs (12%), human immunodeficiency virus (11%), primary immunodeficiency (1%), neutropenia (0.5%) and thymus abnormalities (0.5%). There were frequent enquires to the advice line by UK HCPs regarding immunocompromised travellers. The travellers in this study had a wide range of underlying medical conditions and varying levels of immunocompromise. These enquiries may reflect a lack of clarity in current national guidelines, difficulties in interpreting them or both. Establishing the reasons for these deficiencies as well as the reasons behind UK HCP concerns and lack of confidence requires further investigation. This research has highlighted potential knowledge gaps and will help inform future guidance and educational activities for UK HCPs advising

  5. Travel Behavior Change in Older Travelers: Understanding Critical Reactions to Incidents Encountered in Public Transport

    Directory of Open Access Journals (Sweden)

    Catherine Sundling

    2015-11-01

    Full Text Available Accessibility of travel may be better understood if psychological factors underlying change in travel behavior are known. This paper examines older (65+ travelers’ motives for changing their travel behavior. These changes are grounded in critical incidents earlier encountered in public-transport travel. A scientific framework is developed based on cognitive and behavioral theory. In 29 individual interviews, travelers’ critical reactions (i.e., cognitive, emotional, and/or behavioral to 77 critical incidents were examined. By applying critical incident technique (CIT, five reaction themes were identified that had generated travel-behavior change: firm restrictions, unpredictability, unfair treatment, complicated trips, and earlier adverse experiences. To improve older travelers’ access to public transport, key findings were: (a service must be designed so as to strengthen the feeling of being in control throughout the journey; (b extended personal service would increase predictability in the travel chain and decrease travel complexity; consequently, (c when designing new services and making effective accessibility interventions, policy makers should consider and utilize underlying psychological factors that could direct traveler behavior.

  6. Travel Behavior Change in Older Travelers: Understanding Critical Reactions to Incidents Encountered in Public Transport

    Science.gov (United States)

    Sundling, Catherine

    2015-01-01

    Accessibility of travel may be better understood if psychological factors underlying change in travel behavior are known. This paper examines older (65+) travelers’ motives for changing their travel behavior. These changes are grounded in critical incidents earlier encountered in public-transport travel. A scientific framework is developed based on cognitive and behavioral theory. In 29 individual interviews, travelers’ critical reactions (i.e., cognitive, emotional, and/or behavioral) to 77 critical incidents were examined. By applying critical incident technique (CIT), five reaction themes were identified that had generated travel-behavior change: firm restrictions, unpredictability, unfair treatment, complicated trips, and earlier adverse experiences. To improve older travelers’ access to public transport, key findings were: (a) service must be designed so as to strengthen the feeling of being in control throughout the journey; (b) extended personal service would increase predictability in the travel chain and decrease travel complexity; consequently, (c) when designing new services and making effective accessibility interventions, policy makers should consider and utilize underlying psychological factors that could direct traveler behavior. PMID:26593935

  7. Asymmetric Aldol Additions: A Guided-Inquiry Laboratory Activity on Catalysis

    Science.gov (United States)

    King, Jorge H. Torres; Wang, Hong; Yezierski, Ellen J.

    2018-01-01

    Despite the importance of asymmetric catalysis in both the pharmaceutical and commodity chemicals industries, asymmetric catalysis is under-represented in undergraduate chemistry laboratory curricula. A novel guided-inquiry experiment based on the asymmetric aldol addition was developed. Students conduct lab work to compare the effectiveness of…

  8. Parallel coupling of symmetric and asymmetric exclusion processes

    International Nuclear Information System (INIS)

    Tsekouras, K; Kolomeisky, A B

    2008-01-01

    A system consisting of two parallel coupled channels where particles in one of them follow the rules of totally asymmetric exclusion processes (TASEP) and in another one move as in symmetric simple exclusion processes (SSEP) is investigated theoretically. Particles interact with each other via hard-core exclusion potential, and in the asymmetric channel they can only hop in one direction, while on the symmetric lattice particles jump in both directions with equal probabilities. Inter-channel transitions are also allowed at every site of both lattices. Stationary state properties of the system are solved exactly in the limit of strong couplings between the channels. It is shown that strong symmetric couplings between totally asymmetric and symmetric channels lead to an effective partially asymmetric simple exclusion process (PASEP) and properties of both channels become almost identical. However, strong asymmetric couplings between symmetric and asymmetric channels yield an effective TASEP with nonzero particle flux in the asymmetric channel and zero flux on the symmetric lattice. For intermediate strength of couplings between the lattices a vertical-cluster mean-field method is developed. This approximate approach treats exactly particle dynamics during the vertical transitions between the channels and it neglects the correlations along the channels. Our calculations show that in all cases there are three stationary phases defined by particle dynamics at entrances, at exits or in the bulk of the system, while phase boundaries depend on the strength and symmetry of couplings between the channels. Extensive Monte Carlo computer simulations strongly support our theoretical predictions. Theoretical calculations and computer simulations predict that inter-channel couplings have a strong effect on stationary properties. It is also argued that our results might be relevant for understanding multi-particle dynamics of motor proteins

  9. Multipartite asymmetric quantum cloning

    International Nuclear Information System (INIS)

    Iblisdir, S.; Gisin, N.; Acin, A.; Cerf, N.J.; Filip, R.; Fiurasek, J.

    2005-01-01

    We investigate the optimal distribution of quantum information over multipartite systems in asymmetric settings. We introduce cloning transformations that take N identical replicas of a pure state in any dimension as input and yield a collection of clones with nonidentical fidelities. As an example, if the clones are partitioned into a set of M A clones with fidelity F A and another set of M B clones with fidelity F B , the trade-off between these fidelities is analyzed, and particular cases of optimal N→M A +M B cloning machines are exhibited. We also present an optimal 1→1+1+1 cloning machine, which is an example of a tripartite fully asymmetric cloner. Finally, it is shown how these cloning machines can be optically realized

  10. Time-use and well-being impacts of travel-to-work and travel-for-work

    OpenAIRE

    Wheatley, D; Bickerton, C

    2016-01-01

    This article contributes to understanding of the complex patterns of travel-to-work and travel-for-work which \\ud increasingly characterize highly skilled employment, using 2015 data from a UK Midlands study comprising an online survey and follow-up interviews. Travel-to-work essentially lengthens the working day, and is difficult to use productively, especially when commuting by car. Travel-for-work, by contrast, results in intense schedules \\ud especially when requiring overnight stays. Own...

  11. 49 CFR 229.55 - Piston travel.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Piston travel. 229.55 Section 229.55... Piston travel. (a) Brake cylinder piston travel shall be sufficient to provide brake shoe clearance when... piston travel may not exceed 11/2 inches less than the total possible piston travel. The total possible...

  12. Seasonally asymmetric enhancement of northern vegetation productivity

    Science.gov (United States)

    Park, T.; Myneni, R.

    2017-12-01

    Multiple evidences of widespread greening and increasing terrestrial carbon uptake have been documented. In particular, enhanced gross productivity of northern vegetation has been a critical role leading to observed carbon uptake trend. However, seasonal photosynthetic activity and its contribution to observed annual carbon uptake trend and interannual variability are not well understood. Here, we introduce a multiple-source of datasets including ground, atmospheric and satellite observations, and multiple process-based global vegetation models to understand how seasonal variation of land surface vegetation controls a large-scale carbon exchange. Our analysis clearly shows a seasonally asymmetric enhancement of northern vegetation productivity in growing season during last decades. Particularly, increasing gross productivity in late spring and early summer is obvious and dominant driver explaining observed trend and variability. We observe more asymmetric productivity enhancement in warmer region and this spatially varying asymmetricity in northern vegetation are likely explained by canopy development rate, thermal and light availability. These results imply that continued warming may facilitate amplifying asymmetric vegetation activity and cause these trends to become more pervasive, in turn warming induced regime shift in northern land.

  13. Travel risk behaviours and uptake of pre-travel health preventions by university students in Australia

    Directory of Open Access Journals (Sweden)

    Heywood Anita E

    2012-02-01

    Full Text Available Abstract Background Forward planning and preventative measures before travelling can significantly reduce the risk of many vaccine preventable travel-related infectious diseases. Higher education students may be at an increased risk of importing infectious disease as many undertake multiple visits to regions with higher infectious disease endemicity. Little is known about the health behaviours of domestic or international university students, particularly students from low resource countries who travel to high-resource countries for education. This study aimed to assess travel-associated health risks and preventative behaviours in a sample of both domestic and international university students in Australia. Methods In 2010, a 28 item self-administered online survey was distributed to students enrolled at the University of New South Wales, Sydney, Australia. Multiple methods of distributing links to the online survey were utilised. The survey examined the international travel history, travel intentions, infection control behaviours and self-reported vaccination history. Results A total of 1663 respondents completed the online survey, 22.1% were international students and 83.9% were enrolled at an undergraduate level. Half had travelled internationally in the previous 12 months, with 69% of those travelling only once during that time with no difference in travel from Australia between domestic and international students (p = 0.8. Uptake of pre-travel health advice was low overall with 68% of respondents reporting they had not sought any advice from a health professional prior to their last international trip. Domestic students were more likely to report uptake of a range of preventative travel health measures compared to international students, including diarrhoeal medication, insect repellent, food avoidance and condoms (P Conclusions Our study highlights the need to educate students about the risk associated with travel and improve preventative

  14. Asymmetric Price Responses of Gasoline Stations. Evidence for Heterogeneity of Retailers

    Energy Technology Data Exchange (ETDEWEB)

    Faber, R.P. [Erasmus University Rotterdam, Rotterdam (Netherlands)

    2009-11-15

    This paper studies asymmetric price responses of individual firms, via daily retail prices of almost all gasoline stations in the Netherlands and suggested prices of the five largest oil companies over more than two years. I find that 38% of the stations respond asymmetrically to changes in the spot market price. Hence, asymmetric pricing is not a feature of the market as a whole, but of individual firms. For asymmetrically pricing stations, the asymmetry is substantial directly after a change but disappears after one or two days. I study station-specific characteristics and conclude that asymmetric pricing seems to be a phenomenon that is randomly distributed across stations. I also find that none of the five largest oil companies adjust their suggested prices asymmetrically.

  15. Asymmetric Price Responses of Gasoline Stations. Evidence for Heterogeneity of Retailers

    International Nuclear Information System (INIS)

    Faber, R.P.

    2009-11-01

    This paper studies asymmetric price responses of individual firms, via daily retail prices of almost all gasoline stations in the Netherlands and suggested prices of the five largest oil companies over more than two years. I find that 38% of the stations respond asymmetrically to changes in the spot market price. Hence, asymmetric pricing is not a feature of the market as a whole, but of individual firms. For asymmetrically pricing stations, the asymmetry is substantial directly after a change but disappears after one or two days. I study station-specific characteristics and conclude that asymmetric pricing seems to be a phenomenon that is randomly distributed across stations. I also find that none of the five largest oil companies adjust their suggested prices asymmetrically.

  16. Observation of asymmetric electromagnetic field profiles in chiral metamaterials

    Science.gov (United States)

    Hisamoto, Nobuyuki; Ueda, Tetsuya; Sawada, Kei; Tomita, Satoshi

    2018-02-01

    We experimentally observe asymmetric electromagnetic field profiles along two-dimensional chiral metamaterials. The asymmetric field profiles depending on the chirality and the operation frequency have been reproduced well by the numerical simulation. Around a chiral meta-atom, distribution of a Poynting vector is found to be shifted asymmetrically. These results are explained in terms of an analogy with the side-jump mechanism in the electronic anomalous Hall systems.

  17. Travel and biologic therapy: travel-related infection risk, vaccine response and recommendations.

    Science.gov (United States)

    Hall, Victoria; Johnson, Douglas; Torresi, Joseph

    2018-01-01

    Biologic therapy has revolutionized the management of refractory chronic autoimmune and auto-inflammatory disease, as well as several malignancies, providing rapid symptomatic relief and/or disease remission. Patients receiving biologic therapies have an improved quality of life, facilitating travel to exotic destinations and potentially placing them at risk of a range of infections. For each biologic agent, we review associated travel-related infection risk and expected travel vaccine response and effectiveness. A PUBMED search [vaccination OR vaccine] AND/OR ['specific vaccine'] AND/OR [immunology OR immune response OR response] AND [biologic OR biological OR biologic agent] was performed. A review of the literature was performed in order to develop recommendations on vaccination for patients in receipt of biologic therapy travelling to high-risk travel destinations. There is a paucity of literature in this area, however, it is apparent that travel-related infection risk is increased in patients on biologic therapy and when illness occurs they are at a higher risk of complication and hospitalization. Patients in receipt of biologic agents are deemed as having a high level of immunosuppression-live vaccines, including the yellow fever vaccine, are contraindicated. Inactivated vaccines are considered safe; however, vaccine response can be attenuated by the patient's biologic therapy, thereby resulting in reduced vaccine effectiveness and protection. Best practice requires a collaborative approach between the patient's primary healthcare physician, relevant specialist and travel medicine expert, who should all be familiar with the immunosuppressive and immunomodulatory effects resulting from the biologic therapies. Timing of vaccines should be carefully planned, and if possible, vaccination provided well before established immunosuppression.

  18. Large-Scale Traveling Weather Systems in Mars’ Southern Extratropics

    Science.gov (United States)

    Hollingsworth, Jeffery L.; Kahre, Melinda A.

    2017-10-01

    Between late fall and early spring, Mars’ middle- and high-latitude atmosphere supports strong mean equator-to-pole temperature contrasts and an accompanying mean westerly polar vortex. Observations from both the MGS Thermal Emission Spectrometer (TES) and the MRO Mars Climate Sounder (MCS) indicate that a mean baroclinicity-barotropicity supports intense, large-scale eastward traveling weather systems (i.e., transient synoptic-period waves). Such extratropical weather disturbances are critical components of the global circulation as they serve as agents in the transport of heat and momentum, and generalized scalar/tracer quantities (e.g., atmospheric dust, water-vapor and ice clouds). The character of such traveling extratropical synoptic disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a moderately high-resolution Mars global climate model (Mars GCM). This Mars GCM imposes interactively-lifted and radiatively-active dust based on a threshold value of the surface stress. The model exhibits a reasonable "dust cycle" (i.e., globally averaged, a dustier atmosphere during southern spring and summer occurs). Compared to the northern-hemisphere counterparts, the southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense. Influences of the zonally asymmetric (i.e., east-west varying) topography on southern large-scale weather are investigated, in addition to large-scale up-slope/down-slope flows and the diurnal cycle. A southern storm zone in late winter and early spring presents in the western hemisphere via orographic influences from the Tharsis highlands, and the Argyre and Hellas impact basins. Geographically localized transient-wave activity diagnostics are constructed that illuminate dynamical differences amongst the simulations and these are presented.

  19. Large-Scale Traveling Weather Systems in Mars Southern Extratropics

    Science.gov (United States)

    Hollingsworth, Jeffery L.; Kahre, Melinda A.

    2017-01-01

    Between late fall and early spring, Mars' middle- and high-latitude atmosphere supports strong mean equator-to-pole temperature contrasts and an accompanying mean westerly polar vortex. Observations from both the MGS Thermal Emission Spectrometer (TES) and the MRO Mars Climate Sounder (MCS) indicate that a mean baroclinicity-barotropicity supports intense, large-scale eastward traveling weather systems (i.e., transient synoptic-period waves). Such extratropical weather disturbances are critical components of the global circulation as they serve as agents in the transport of heat and momentum, and generalized scalar/tracer quantities (e.g., atmospheric dust, water-vapor and ice clouds). The character of such traveling extratropical synoptic disturbances in Mars' southern hemisphere during late winter through early spring is investigated using a moderately high-resolution Mars global climate model (Mars GCM). This Mars GCM imposes interactively-lifted and radiatively-active dust based on a threshold value of the surface stress. The model exhibits a reasonable "dust cycle" (i.e., globally averaged, a dustier atmosphere during southern spring and summer occurs). Compared to the northern-hemisphere counterparts, the southern synoptic-period weather disturbances and accompanying frontal waves have smaller meridional and zonal scales, and are far less intense. Influences of the zonally asymmetric (i.e., east-west varying) topography on southern large-scale weather are investigated, in addition to large-scale up-slope/down-slope flows and the diurnal cycle. A southern storm zone in late winter and early spring presents in the western hemisphere via orographic influences from the Tharsis highlands, and the Argyre and Hellas impact basins. Geographically localized transient-wave activity diagnostics are constructed that illuminate dynamical differences amongst the simulations and these are presented.

  20. Travel time data collection handbook

    Science.gov (United States)

    1998-03-01

    This Travel Time Data Collection Handbook provides guidance to transportation : professionals and practitioners for the collection, reduction, and presentation : of travel time data. The handbook should be a useful reference for designing : travel ti...

  1. The value of travel time variance

    OpenAIRE

    Fosgerau, Mogens; Engelson, Leonid

    2010-01-01

    This paper considers the value of travel time variability under scheduling preferences that are de�fined in terms of linearly time-varying utility rates associated with being at the origin and at the destination. The main result is a simple expression for the value of travel time variability that does not depend on the shape of the travel time distribution. The related measure of travel time variability is the variance of travel time. These conclusions apply equally to travellers who can free...

  2. Approaches to groundwater travel time

    International Nuclear Information System (INIS)

    Kaplan, P.; Klavetter, E.; Peters, R.

    1989-01-01

    One of the objectives of performance assessment for the Yucca Mountain Project is to estimate the groundwater travel time at Yucca Mountain, Nevada, to determine whether the site complies with the criteria specified in the Code of Federal Regulations, Title 10 CFR 60.113 (a). The numerical standard for performance in these criteria is based on the groundwater travel time along the fastest path of likely radionuclide transport from the disturbed zone to the accessible environment. The concept of groundwater travel time as proposed in the regulations, does not have a unique mathematical statement. The purpose of this paper is to discuss the ambiguities associated with the regulatory specification of groundwater travel time, two different interpretations of groundwater travel time, and the effect of the two interpretations on estimates of the groundwater travel time

  3. A Solution Approach from an Analytic Model to Heuristic Algorithm for Special Case of Vehicle Routing Problem with Stochastic Demands

    Directory of Open Access Journals (Sweden)

    2009-03-01

    Full Text Available We define a special case for the vehicle routing problem with stochastic demands (SC-VRPSD where customer demands are normally distributed. We propose a new linear model for computing the expected length of a tour in SC-VRPSD. The proposed model is based on the integration of the “Traveling Salesman Problem” (TSP and the Assignment Problem. For large-scale problems, we also use an Iterated Local Search (ILS algorithm in order to reach an effective solution.

  4. The Expanded Invasive Weed Optimization Metaheuristic for Solving Continuous and Discrete Optimization Problems

    Directory of Open Access Journals (Sweden)

    Henryk Josiński

    2014-01-01

    Full Text Available This paper introduces an expanded version of the Invasive Weed Optimization algorithm (exIWO distinguished by the hybrid strategy of the search space exploration proposed by the authors. The algorithm is evaluated by solving three well-known optimization problems: minimization of numerical functions, feature selection, and the Mona Lisa TSP Challenge as one of the instances of the traveling salesman problem. The achieved results are compared with analogous outcomes produced by other optimization methods reported in the literature.

  5. Adolescent school travel: Is online mapping a practical alternative to GPS-assessed travel routes?

    DEFF Research Database (Denmark)

    Stewart, Tom; Schipperijn, Jasper; Snizek, Bernhard

    2017-01-01

    AbstractBackground Geographically accurate travel routes are necessary to estimate exposure to the environment and its potential influence on travel behaviour. Although assessing travel behaviours with Global Positioning System (GPS) receivers is increasingly common, these protocols place......-reporting error seems more pronounced for longer routes, and when multiple travel modes are used. Researchers should consider the advantages (e.g., ease of collection) and disadvantages (e.g., lack of temporal information) when deciding if the data obtainable are sufficient to answer their research questions....

  6. A new convenient asymmetric approach to herbarumin Ⅲ

    Institute of Scientific and Technical Information of China (English)

    Xue Song Chen; Shi Jun Da; Li Hong Yang; Bo Yan Xu; Zhi Xiang Xie; Ying Li

    2007-01-01

    The asymmetric total synthesis of herbarumin Ⅲ 3, a naturally occurred phytotoxin, along with 8-epi-herbarumin Ⅲ 22, was succeeded in 12 steps from n-butyraldehyde based on Brown's asymmetric allylation, taking modified Julia olefination and Yamaguchi's macro-lactonization as key steps.

  7. Fourier synthesis of asymmetrical optical potentials for atoms

    International Nuclear Information System (INIS)

    Ritt, G.

    2007-01-01

    In this work a dissipationless asymmetrical optical potential for cold atoms was produced. In a first step a new type of optical lattice was generated, whose spatial periodicity only corresponds to a quarter of the wavelength of the light used for the generation. This corresponds to the half of the periodicity of a conventional optical lattice, which is formed by the light of the same wavelength. The generation of this new type of optical lattice was reached by the use of two degenerated raman transitions. Virtual processes occur, in which four photons are involved. In conventional optical lattices however virtual two-photon processes occur. By spatially superimposing this optical lattice with a conventional optical lattice an asymmetrical optical potential could be formed. By diffraction of a Bose Einstein condensate of rubidium atoms at the transient activated asymmetrical potential the asymmetrical structure was proven. (orig.)

  8. Business travel and sustainability. Part III. In: Handbook of Sustainable Travel: People, Society, and Transportation Systems

    OpenAIRE

    AGUILERA, Anne

    2013-01-01

    Business travel has been relatively neglected in strategies to promote sustainable travel. A two-stage approach is taken beginning by showing how sustainability of business travel is relevant not only environmentally, but also from an economic and social perspective. On the one hand, this form of travel helps to generate jobs in numerous business sectors, not only in transportation. On the other hand, the social dimension cannot be ignored either, since business travel is often a source of fa...

  9. Travellers and influenza: risks and prevention.

    Science.gov (United States)

    Goeijenbier, M; van Genderen, P; Ward, B J; Wilder-Smith, A; Steffen, R; Osterhaus, A D M E

    2017-01-01

    Influenza viruses are among the major causes of serious human respiratory tract infection worldwide. In line with the high disease burden attributable to influenza, these viruses play an important, but often neglected, role in travel medicine. Guidelines and recommendations regarding prevention and management of influenza in travellers are scarce. Of special interest for travel medicine are risk populations and also circumstances that facilitate influenza virus transmission and spread, like travel by airplane or cruise ship and mass gatherings. We conducted a PUBMED/MEDLINE search for a combination of the MeSH terms Influenza virus, travel, mass gathering, large scale events and cruise ship. In addition we gathered guidelines and recommendations from selected countries and regarding influenza prevention and management in travellers. By reviewing these search results in the light of published knowledge in the fields of influenza prevention and management, we present best practice advice for the prevention and management of influenza in travel medicine. Seasonal influenza is among the most prevalent infectious diseases in travellers. Known host-associated risk factors include extremes of age and being immune-compromised, while the most relevant environmental factors are associated with holiday cruises and mass gatherings. Pre-travel advice should address influenza and its prevention for travellers, whenever appropriate on the basis of the epidemiological situation concerned. Preventative measures should be strongly recommended for travellers at high-risk for developing complications. In addition, seasonal influenza vaccination should be considered for any traveller wishing to reduce the risk of incapacitation, particularly cruise ship crew and passengers, as well as those participating in mass gatherings. Besides advice concerning preventive measures and vaccination, advice on the use of antivirals may be considered for some travellers. © International Society of

  10. Engineered Asymmetric Composite Membranes with Rectifying Properties.

    Science.gov (United States)

    Wen, Liping; Xiao, Kai; Sainath, Annadanam V Sesha; Komura, Motonori; Kong, Xiang-Yu; Xie, Ganhua; Zhang, Zhen; Tian, Ye; Iyoda, Tomokazu; Jiang, Lei

    2016-01-27

    Asymmetric composite membranes with rectifying properties are developed by grafting pH-stimulus-responsive materials onto the top layer of the composite structure, which is prepared by two novel block copolymers using a phase-separation technique. This engineered asymmetric composite membrane shows potential applications in sensors, filtration, and nanofluidic devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. A stated adaptation approach to assess changes in individuals’ activity-travel behavior in presence of personalized travel information

    NARCIS (Netherlands)

    Parvaneh, Zahra; Arentze, Theo; Timmermans, Harry

    2014-01-01

    The rapid and inevitable growth of availability of travel information for travellers has increased expectations among policy makers about the benefits of travel information. It is increasingly expected that providing advanced travel information can trigger particular travel behaviors that would

  12. Post-travel screening of asymptomatic long-term travelers to the tropics for intestinal parasites using molecular diagnostics.

    Science.gov (United States)

    Soonawala, Darius; van Lieshout, Lisette; den Boer, Marion A M; Claas, Eric C J; Verweij, Jaco J; Godkewitsch, André; Ratering, Marchel; Visser, Leo G

    2014-05-01

    The incidence of asymptomatic travel-related parasitic infection is uncertain. Previous studies did not distinguish new incident infections, from past infections. Regardless of symptoms, we performed multiplex real-time polymerase chain reaction on pre- and post-travel stool samples of Dutch long-term travelers to the (sub)tropics. Serological screening for Schistosoma spp. was only performed in travelers to sub-Saharan Africa. In total, 679 travelers were included in the study. The follow-up rate was 82% (556 of 679). Participants' median travel duration was 12 weeks. There was one incident infection with Strongyloides stercoralis; there were none with Entamoeba histolytica, 4 with Cryptosporidium spp. (1%), and 22 with Giardia lamblia (4%). Nine of 146 travelers (6%) seroconverted for Schistosoma spp. Routine screening of stool samples for parasitic infection is not indicated for asymptomatic people, who travel to the (sub)tropics for up to 3 months. Screening for Schistosoma spp. should be offered to travelers with fresh-water contact in endemic regions.

  13. Approaches to groundwater travel time

    International Nuclear Information System (INIS)

    Kaplan, P.; Klavetter, E.; Peters, R.

    1989-01-01

    One of the objectives of performance assessment for the Yucca Mountain Project is to estimate the groundwater travel time at Yucca Mountain, Nevada, to determine whether the site complies with the criteria specified in the Code of Federal Regulations. The numerical standard for performance in these criteria is based on the groundwater travel time along the fastest path of likely radionuclide transport from the disturbed zone to the accessible environment. The concept of groundwater travel time, as proposed in the regulations, does not have a unique mathematical statement. The purpose of this paper is to discuss (1) the ambiguities associated with the regulatory specification of groundwater travel time, (2) two different interpretations of groundwater travel time, and (3) the effect of the two interpretations on estimates of the groundwater travel time. 3 refs., 2 figs., 2 tabs

  14. Variable angle asymmetric cut monochromator

    International Nuclear Information System (INIS)

    Smither, R.K.; Fernandez, P.B.

    1993-09-01

    A variable incident angle, asymmetric cut, double crystal monochromator was tested for use on beamlines at the Advanced Photon Source (APS). For both undulator and wiggler beams the monochromator can expand area of footprint of beam on surface of the crystals to 50 times the area of incident beam; this will reduce the slope errors by a factor of 2500. The asymmetric cut allows one to increase the acceptance angle for incident radiation and obtain a better match to the opening angle of the incident beam. This can increase intensity of the diffracted beam by a factor of 2 to 5 and can make the beam more monochromatic, as well. The monochromator consists of two matched, asymmetric cut (18 degrees), silicon crystals mounted so that they can be rotated about three independent axes. Rotation around the first axis controls the Bragg angle. The second rotation axis is perpendicular to the diffraction planes and controls the increase of the area of the footprint of the beam on the crystal surface. Rotation around the third axis controls the angle between the surface of the crystal and the wider, horizontal axis for the beam and can make the footprint a rectangle with a minimum. length for this area. The asymmetric cut is 18 degrees for the matched pair of crystals, which allows one to expand the footprint area by a factor of 50 for Bragg angles up to 19.15 degrees (6 keV for Si[111] planes). This monochromator, with proper cooling, will be useful for analyzing the high intensity x-ray beams produced by both undulators and wigglers at the APS

  15. Fecal-orally transmitted diseases among travelers are decreasing due to better hygienic standards at travel destination.

    Science.gov (United States)

    Baaten, Gijs G; Sonder, Gerard J B; Van Der Loeff, Maarten F Schim; Coutinho, Roel A; Van Den Hoek, Anneke

    2010-01-01

    To evaluate whether changes in attack rates of fecal-orally transmitted diseases among travelers are related to changes in pretravel vaccination practices or better hygienic standards at travel destination. National surveillance data on all laboratory-confirmed cases of travel-related hepatitis A, shigellosis, and typhoid fever diagnosed in the Netherlands from 1995 to 2006 were matched with the number of Dutch travelers to developing countries to calculate region-specific annual attack rates. Trends in attack rates of non-vaccine-preventable shigellosis were compared with those of vaccine-preventable hepatitis A and typhoid fever. Trends were also compared with three markers for hygienic standards of the local population at travel destinations, drawn from the United Nations Development Programme database: the human development index, the sanitation index, and the water source index. Attack rates among Dutch travelers to developing regions declined for hepatitis A, shigellosis, and typhoid fever. Region-specific trends in attack rates of shigellosis resembled trends of hepatitis A and typhoid fever. Declining attack rates of the three fecal-orally transmitted diseases correlated with improvements in socioeconomic, sanitary, and water supply conditions of the local population at travel destination. These findings suggest that improved hygienic standards at travel destination strongly contributed to the overall decline in attack rates of fecal-orally transmitted diseases among visiting travelers. © 2010 International Society of Travel Medicine.

  16. 41 CFR 301-75.204 - May we use Government contractor-issued travelers checks to pay for the interviewee's travel...

    Science.gov (United States)

    2010-07-01

    ... contractor-issued travelers checks to pay for the interviewee's travel expenses? 301-75.204 Section 301-75.204 Public Contracts and Property Management Federal Travel Regulation System TEMPORARY DUTY (TDY) TRAVEL ALLOWANCES AGENCY RESPONSIBILITIES 75-PRE-EMPLOYMENT INTERVIEW TRAVEL Obtaining Travel Services...

  17. Travel-related acquisition of diarrhoeagenic bacteria, enteral viruses and parasites in a prospective cohort of 98 Dutch travellers.

    Science.gov (United States)

    van Hattem, Jarne M; Arcilla, Maris S; Grobusch, Martin P; Bart, Aldert; Bootsma, Martin C; van Genderen, Perry J; van Gool, Tom; Goorhuis, Abraham; van Hellemond, Jaap J; Molenkamp, Richard; Molhoek, Nicky; Oude Lashof, Astrid M; Stobberingh, Ellen E; de Wever, Bob; Verbrugh, Henri A; Melles, Damian C; Penders, John; Schultsz, Constance; de Jong, Menno D

    2017-09-01

    Limited prospective data are available on the acquisition of viral, bacterial and parasitic diarrhoeagenic agents by healthy individuals during travel. To determine the frequency of travel associated acquisition of 19 pathogens in 98 intercontinental travellers, qPCR was used to detect 8 viral pathogens, 6 bacterial enteric pathogens and 5 parasite species in faecal samples collected immediately before and after travel. We found high pre-travel carriage rates of Blastocystis spp. and Dientamoeba fragilis of 32% and 19% respectively. Pre-travel prevalences of all other tested pathogens were below 3%. Blastocystis spp. (10%), Plesiomonas shigelloides (7%), D. fragilis (6%) and Shigella spp. (5%) were the most frequently acquired pathogens and acquisition of enteral viruses and hepatitis E virus in this relatively small group of travellers was rare or non-existent. Our findings suggest that the role of viruses as the cause of persisting traveller's diarrhoea is limited and bacterial pathogens are more likely as a cause of traveller's diarrhoea. The substantial proportion of travellers carrying Blastocystis spp. and D. fragilis before travel warrants cautious interpretation of positive samples in returning travellers with gastrointestinal complaints. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. The Development of Independent Travel in China in the Future and Travel Agents’ Coping Strategies

    OpenAIRE

    Pan, Yulu

    2010-01-01

    Abstract The purpose of this research is to understand the general trend of independent travel in China from tourists’ perspectives and what strategies travel agents should adopt to cope with the increased independent travel. This project is based on both primary research and secondary research. Quantitative and qualitative data are collected and analyzed for deeply exploration about independent travel in order to understand tourists’ attitudes, expectations and perspectives. By this w...

  19. Safe travels? HIV transmission among Britons travelling abroad.

    Science.gov (United States)

    Rice, B; Gilbart, V L; Lawrence, J; Smith, R; Kall, M; Delpech, V

    2012-05-01

    The aim of the study was to identify and describe the characteristics of persons born in the UK who acquire HIV infection abroad. Analyses using case reports and follow-up data from the national HIV database held at the Health Protection Agency were performed. Fifteen per cent (2066 of 13 891) of UK-born adults diagnosed in England, Wales and Northern Ireland between 2002 and 2010 acquired HIV infection abroad. Thailand (534), the USA (117) and South Africa (108) were the countries most commonly reported. As compared with UK-born adults acquiring HIV infection in the UK, those acquiring HIV infection abroad were significantly (P sex with a commercial sex worker (5.6% vs. 1%, respectively). Among men infected in Thailand, 11% reported sex with a commercial sex worker. A substantial number of UK-born adults are acquiring HIV infection in countries with generalized HIV epidemics, and in common holiday destinations. Of particular concern is the high proportion of men infected reporting sex with a commercial sex worker. We recommend HIV prevention and testing efforts be extended to include travellers abroad, and that sexual health advice be provided routinely in travel health consultations and in occupational health travel advice packs, particularly to those travelling to high HIV prevalence areas and destinations for sex tourism. Safer sex messages should include an awareness of the potential detrimental health and social impacts of the sex industry. © 2012 British HIV Association.

  20. Pre-travel advice at a crossroad: Medical preparedness of travellers to South and Southeast-Asia - The Hamburg Airport Survey.

    Science.gov (United States)

    Rolling, Thierry; Mühlenpfordt, Melina; Addo, Marylyn M; Cramer, Jakob P; Vinnemeier, Christof D

    Specific travel-related recommendations exist for the prevention or self-treatment of infectious diseases contracted by travellers to the tropics. In the current study, we assessed the medical preparedness per these recommendations, focusing on whether travellers carried antidiarrheal and antimalarial medication with them stratified by type of pre-travel advice. We surveyed travellers departing from Hamburg International Airport to South or Southeast Asia, using a questionnaire on demographic, medical and travel characteristics. 975 travellers were analysed - the majority (817, 83%) being tourists. A large proportion packed any antidiarrheal medication (612, 63%) - most frequently loperamide (440, 72%). Only 176 of 928 (19%) travellers to destinations with low-to medium risk for malaria packed a recommended antimalarial medication. The majority (162, 17%) of them carried antimalarials as stand-by emergency treatment (SBET). 468 (48%) travellers had a pre-travel medical consultation. This lead to higher odds of carrying SBET- with the highest odds associated with a consultation at a travel medicine specialist (OR 7.83 compared to no consultation). Attending a travel medicine specialist was associated with better adherence to current recommendations concerning the carriage of stand-by emergency treatment of malaria. However, the proportion of travellers seeking pre-travel health advice was overall low in our population. Promoting pre-travel consultations may, therefore, lead to higher adherence to the current recommendations in travel medicine. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Common Health Risks, Required Precautions of Travelers and their Customs Towards the Use of Travel Medicine Services.

    Science.gov (United States)

    Roupa, Zoe; Zikos, Dimitrios; Vasilopoulos, Aristides; Diomidous, Marianna

    2012-01-01

    There is an increasing number of people who travel around the world. Every traveler is exposed to nearly all infectious risks which may occur during his travel time. Some of the main risk factors can be water quality, temperature and high humidity and the exposure to multi-resistant microorganisms. To tackle the upcoming problem there is an imperative need to develop a new branch of medicine with the name of travel medicine. A consultation prior to departure for an upcoming trip is required, focusing to a personalized healthcare plan, based on international scientific protocols and epidemiological studies.Travelers must acquire essential information about the prevailing hygiene conditions and climatic differentiations that occur in the region. Additionally there are several health risks upon the arrival at destination. A scheduled visit to a health professional is necessary, especially in the case of travelers suffering from chronic diseases or those taking medication, while vaccination is considered essential for specific destination countries. Healthcare professionals should be able to inform travelers and evaluate their needs. According to research studies on notion and attitudes travelers' specific risks, only few of them are well-informed during a trip. While most studies indicate that travelers have some kind of pre travel medical consultation, not all of them proceed to the required vaccinations and medications. Travelling for business or leisure around the world may be unhealthy. The importance of proper preparation prior to the travel requires to be adequately informed by specialized healthcare professionals, and to receive appropriate vaccinations and medications, when required. The results of the review of notions and attitudes of travelers during the trip indicate not only the need for further development of the branch of travel medicine but especially the need for the expansion and the availability of health services.

  2. International travel in the immunocompromised patient: a cross-sectional survey of travel advice in 254 consecutive patients.

    Science.gov (United States)

    Bialy, C; Horne, K; Dendle, C; Kanellis, J; Littlejohn, G; Ratnam, I; Woolley, I

    2015-06-01

    Our primary aim was to determine the rate of overseas travel in immunocompromised individuals attending appropriate clinics at an Australian tertiary care hospital. We also aimed to characterise health-seeking behaviour prior to travel and investigated sources of pre-travel advice, compared travel patterns and activities between three specific immunosuppressed groups, and examined pre-immunosuppression patient serology. We implemented a cross-sectional survey of patients between February and August 2012. This survey was implemented among three outpatient populations at Monash Medical Centre, an Australian tertiary care hospital. We recruited 254 immunosuppressed adults from three patient populations: human immunodeficiency virus-positive individuals, renal transplant patients and rheumatology patients requiring immunosuppressive therapy. No clinical intervention was performed. In the 10 years preceding the survey, 153 (60.2%) participants reported international travel. Of these, 105 (68.6%) were immunosuppressed at the time of travel. These patients were 47.6% male and 60% Australian born. Forty per cent were visiting friends and relatives as part of their travel. Fifty-four per cent of those immunocompromised at the time of travel were going to high-risk destinations. Pathology files indicated that serological screening was frequently not performed prior to immunosuppression in the renal transplant and rheumatology groups. Immunocompromised patients often travel to high-risk destinations with limited or inadequate pre-travel preparations. Doctors caring for the immunocompromised should be aware of travel risks, suitable vaccination protocols and when to refer to specialist travel clinics. © 2015 Royal Australasian College of Physicians.

  3. Season and weather effects on travel-related mood and travel satisfaction

    NARCIS (Netherlands)

    Ettema, Dick; Friman, Margareta; Olsson, Lars E.; Gärling, Tommy

    2017-01-01

    This study examines the effects of season and weather on mood (valence and activation) and travel satisfaction (measured by the Satisfaction with Travel Scale). Analyses are presented of 562 time-sampled morning commutes to work made by 363 randomly sampled people in three different Swedish cities

  4. Pre-travel advice concerning vector-borne diseases received by travelers prior to visiting Cuzco, Peru.

    Science.gov (United States)

    Mejia, Christian R; Centeno, Emperatriz; Cruz, Briggitte; Cvetkovic-Vega, Aleksandar; Delgado, Edison; Rodriguez-Morales, Alfonso J

    2016-01-01

    Peru is an increasingly popular tourist destination that poses a risk to travelers due to endemic vector-borne diseases (VBDs). The objective of our study was to determine which factors are associated with receiving pre-travel advice (PTA) for VBDs among travelers visiting Cuzco, Peru. A cross-sectional secondary analysis based on data from a survey among travelers departing Cuzco at Alejandro Velazco Astete International Airport during the period January-March 2012 was conducted. From the 1819 travelers included in the original study, 1717 were included in secondary data analysis. Of these participants, 42.2% received PTA and 2.9% were informed about vector-borne diseases, including yellow fever (1.8%), malaria (1.6%) and dengue fever (0.1%). Receiving information on VBDs was associated with visiting areas endemic to yellow fever and dengue fever in Peru. The only disease travelers received specific recommendations for before visiting an endemic area for was yellow fever. Only 1 in 30 tourists received information on VBD prevention; few of those who traveled to an endemic area were warned about specific risks for infectious diseases prior to their trip. These important findings show that most tourists who travel to Peru do not receive PTA for the prevention of infectious and VBD, which can affect not only the travelers but their countries of origin as well. Copyright © 2015 King Saud Bin Abdulaziz University for Health Sciences. Published by Elsevier Ltd. All rights reserved.

  5. Immunocompromised Travelers: Demographic Characteristics, Travel Destinations, and Pretravel Health Care from the U.S. Global TravEpiNet Consortium.

    Science.gov (United States)

    Schwartz, Brian S; Rosen, Jessica; Han, Pauline V; Hynes, Noreen A; Hagmann, Stefan H; Rao, Sowmya R; Jentes, Emily S; Ryan, Edward T; LaRocque, Regina C

    2015-11-01

    An increasing number of immunocompromised individuals are pursuing international travel, and a better understanding of their international travel patterns and pretravel health care is needed. We evaluated the clinical features, itineraries, and pretravel health care of 486 immunocompromised international travelers seen at Global TravEpiNet sites from January 2009 to June 2012. We used bivariate analyses and logistic regressions using random intercept models to compare demographic and travel characteristics, vaccines administered, and medications prescribed for immunocompromised travelers versus 30,702 immunocompetent travelers. Immunocompromised travelers pursued itineraries that were largely similar to those of immunocompetent travelers, with nearly one-third of such travelers visiting countries with low human development indices. Biological agents, including tumor necrosis factor blockers, were commonly used immunosuppressive medications among immunocompromised travelers. A strong collaboration between travel-medicine specialists, primary care doctors, and specialist physicians is needed to prepare immunocompromised people for international travel. Incorporating routine questioning and planning regarding travel into the primary care visits of immunocompromised people may be useful. © The American Society of Tropical Medicine and Hygiene.

  6. Network structure and travel time perception.

    Science.gov (United States)

    Parthasarathi, Pavithra; Levinson, David; Hochmair, Hartwig

    2013-01-01

    The purpose of this research is to test the systematic variation in the perception of travel time among travelers and relate the variation to the underlying street network structure. Travel survey data from the Twin Cities metropolitan area (which includes the cities of Minneapolis and St. Paul) is used for the analysis. Travelers are classified into two groups based on the ratio of perceived and estimated commute travel time. The measures of network structure are estimated using the street network along the identified commute route. T-test comparisons are conducted to identify statistically significant differences in estimated network measures between the two traveler groups. The combined effect of these estimated network measures on travel time is then analyzed using regression models. The results from the t-test and regression analyses confirm the influence of the underlying network structure on the perception of travel time.

  7. Travels in Architectural History

    Directory of Open Access Journals (Sweden)

    Davide Deriu

    2016-11-01

    Full Text Available Travel is a powerful force in shaping the perception of the modern world and plays an ever-growing role within architectural and urban cultures. Inextricably linked to political and ideological issues, travel redefines places and landscapes through new transport infrastructures and buildings. Architecture, in turn, is reconstructed through visual and textual narratives produced by scores of modern travellers — including writers and artists along with architects themselves. In the age of the camera, travel is bound up with new kinds of imaginaries; private records and recollections often mingle with official, stereotyped views, as the value of architectural heritage increasingly rests on the mechanical reproduction of its images. Whilst students often learn about architectural history through image collections, the place of the journey in the formation of the architect itself shifts. No longer a lone and passionate antiquarian or an itinerant designer, the modern architect eagerly hops on buses, trains, and planes in pursuit of personal as well as professional interests. Increasingly built on a presumption of mobility, architectural culture integrates travel into cultural debates and design experiments. By addressing such issues from a variety of perspectives, this collection, a special 'Architectural Histories' issue on travel, prompts us to rethink the mobile conditions in which architecture has historically been produced and received.

  8. Prevention of influenza among travellers attending at a UK travel clinic: beliefs and perceptions. A cross-sectional study.

    Science.gov (United States)

    Masuet-Aumatell, Cristina; Toovey, Stephen; Zuckerman, Jane N

    2013-07-01

    Travellers' compliance with measures to prevent influenza through the use of antivirals and influenza vaccine remains very poor despite influenza being one of the commonest travel and vaccine-preventable diseases. A study was undertaken to assess travellers' beliefs, perceptions and intentions to take antivirals for the treatment and prevention of influenza during the H1N1 pandemic. A cross-sectional survey (n = 96) of travellers who attended the Royal Free Travel Health Centre, London, UK was undertaken in September 2009. A self-administered questionnaire was completed by a traveller in advance of their pre-travel health consultation. Logistic regression identified variables independently associated with compliance. Influenza vaccination uptake for the 5 years preceding the study was found to be 20·8%. This was statistically significantly higher for older travellers and those with underlying health conditions (P study identifies some beliefs and perceptions travellers consider with regard to the therapeutic and preventive influenza use of antivirals during the H1N1 pandemic; it underscores the importance of travellers receiving hemisphere appropriate influenza vaccination. The external validity of these study findings requires further corroboration involving other travel clinics and different cohorts of travellers during seasonal activity or outbreaks of influenza. These findings could guide the development of future strategies for the prevention of influenza in travellers. © 2012 John Wiley & Sons Ltd.

  9. Morbidity among Israeli paediatric travellers.

    Science.gov (United States)

    Rabinowicz, Shira; Schwartz, Eli

    2017-09-01

    International travel, particularly to developing countries, is becoming increasingly common among the Israeli population, including an increase in the number of travelling children. Since children are a distinct travellers' population, data about their post-travel morbidity are needed. A retrospective study which examined all children (0-19 years old) who presented to our centre after international travel from 1999 to 2015. About 314 children were seen. The mean age was 10 years (SD ± 5.8). Most of the patients (80.6%) were tourists, and the rest were expatriates. The main destinations visited were South-Asia (46.5%), Sub-Saharan Africa (33.4%), Latin-America (7%) and Europe (6.4%). Overall, the most common diagnoses were gastrointestinal (GI) (mainly chronic) disorders (30.6%), followed by febrile diseases (26.4%), among which 18.1% of patients were diagnosed with dengue fever and 12% with malaria. Dermatologic conditions accounted for 25.2%. Additional diagnoses were schistosomiasis (6.4%) and neuropsychiatric symptoms (2.2%). A substantial part, 10.8%, had eosinophilia, either symptomatic or asymptomatic. Travellers to Asia, compared to travellers to Africa, presented more commonly with GI illness (OR 2.02, 95% confidence interval 1.13-3.61), and dermatologic conditions (OR 1.94, 95% confidence interval 1.05-3.61). Morbidity was associated with a variety of transmission modes, such as food-borne illnesses (30.9%), bite and sting wounds (10.2%), mosquito-borne infections (8%), freshwater contact (6.7%) and tick-borne infections (2.2%). The main conditions seen in paediatric returning travellers were GI, febrile and dermatologic illnesses, some may be rare in their country of origin. Targeting care for the suspected pathogens based on updated knowledge of epidemiology and thorough travel history is essential. © International Society of Travel Medicine, 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com

  10. Travel mode choice and travel satisfaction : bridging the gap between decision utility and experienced utility

    OpenAIRE

    De Vos, Jonas; Mokhtarian, Patricia L; Schwanen, Tim; Van Acker, Veronique; Witlox, Frank

    2016-01-01

    Over the past decades research on travel mode choice has evolved from work that is informed by utility theory, examining the effects of objective determinants, to studies incorporating more subjective variables such as habits and attitudes. Recently, the way people perceive their travel has been analyzed with transportation-oriented scales of subjective wellbeing, and particularly the satisfaction with travel scale. However, studies analyzing the link between travel mode choice (i.e., decisio...

  11. Reduction of travellers' diarrhoea by WC/rBS oral cholera vaccine in young, high-risk travellers.

    Science.gov (United States)

    Torrell, Josep Ma Ramon; Aumatell, Cristina Masuet; Ramos, Sergi Morchon; Mestre, Laura Gavaldà; Salas, Carme Micheo

    2009-06-19

    A bidirectional cohort study investigates whether pre-travel vaccination with whole cell/recombinant B subunit inactivated, killed oral cholera vaccine reduces the incidence of diarrhoea in young adult travellers to high-risk areas. Risk of travellers' diarrhoea was assessed according to destination and reason for travel in high-risk travellers of a travel clinic in Barcelona, Spain. Those at high-risk between January and December 2005 were advised on water/food safety and hygiene. High-risk travellers between January and December 2006 were additionally vaccinated with WC/rBS oral cholera vaccine. Data regarding diarrhoea were gathered by structured telephone interview or e-mailed questionnaire following the travellers' return. The incidence of diarrhoea in the group vaccinated with WC/rBS oral cholera vaccine (n=321) was 17.4%, compared with 39.7% in the non-vaccinated group (n=337) (adjusted risk ratio 0.40). The first episode was significantly shorter in the vaccinated group (mean 2.3 days) than in the non-vaccinated group (mean 3.8 days) (pyoung, high-risk travellers. Vaccination with the WC/rBS oral cholera vaccine as well as food safety and hygiene advice could offer effective means of reducing the risk of diarrhoea while abroad.

  12. Travel/Travelers and Parasitic Diseases

    Science.gov (United States)

    ... of the world and specific country. Many infectious diseases transmitted in food and water can also be acquired directly through the fecal-oral route. Parasitic Illnesses That Can Be Acquired During Travel* From Contaminated Food and Water More ... filariasis African sleeping sickness Onchoceriasis *This list ...

  13. Decrease in back strength in asymmetric trunk postures

    NARCIS (Netherlands)

    Vink, P.; Daanen, H. A M; Meijst, W. J.; Ligteringen, J.

    1992-01-01

    The extension force against resistance was recorded in 23 postures for 12 subjects to find explanations for the decrease in back strength in asymmetric postures. A reduction in muscle force in asymmetric postures was found up to 40%, but was strongly dependent on the plane in which asymmetry

  14. Calculation of groundwater travel time

    International Nuclear Information System (INIS)

    Arnett, R.C.; Sagar, B.; Baca, R.G.

    1984-12-01

    Pre-waste-emplacement groundwater travel time is one indicator of the isolation capability of the geologic system surrounding a repository. Two distinct modeling approaches exist for prediction of groundwater flow paths and travel times from the repository location to the designated accessible environment boundary. These two approaches are: (1) the deterministic approach which calculates a single value prediction of groundwater travel time based on average values for input parameters and (2) the stochastic approach which yields a distribution of possible groundwater travel times as a function of the nature and magnitude of uncertainties in the model inputs. The purposes of this report are to (1) document the theoretical (i.e., mathematical) basis used to calculate groundwater pathlines and travel times in a basalt system, (2) outline limitations and ranges of applicability of the deterministic modeling approach, and (3) explain the motivation for the use of the stochastic modeling approach currently being used to predict groundwater pathlines and travel times for the Hanford Site. Example calculations of groundwater travel times are presented to highlight and compare the differences between the deterministic and stochastic modeling approaches. 28 refs

  15. Future Trends in Business Travel Decision Making

    Science.gov (United States)

    Mason, Keith J.

    2002-01-01

    This research surveys twenty large companies and their travellers to identify and evaluate the effects of pressures on the business travel market in the future. The influence of the following areas on the decision making process are addressed: (1) Corporate travel policies and increasing professionalism in corporate purchasing; (2) The development of global strategic airline alliances; (3) The emergence of low cost airlines on short haul markets; and (4) The development of internet based booking tools and travel agency IT. The survey shows differences in views between travel managers, and travellers with regard to corporate travel policies. While travel managers see policy rules, travellers interpret these as guidelines, indicating travel managers will need to take further actions to exercise true control of travel budgets. The data shows that companies are more likely to prescribe a class of airline ticket, than the choice of airline itself. Corporate hierarchical bias in travel policies is still common both for short and particularly long haul flying. Other findings show that while travel managers believe that their companies are likely to sign global deals with strategic airline groups within a five year period in a bid to consolidating spending, they also believe that nearly a third of short haul flying will be taken with low cost carriers, indicating further penetration in this business travel market by these carriers. The paper also provides other predictions about the business travel market, based on the survey findings.

  16. Travelers' Health: Water Disinfection for Travelers

    Science.gov (United States)

    ... Safety Road Safety - 8 Steps MERS Health Advisory poster MERS Pictogram CDC Guide for Healthy Travel Website ... compressed carbon, or large-pore hollow-fiber filter elements are sufficient to remove bacteria and protozoan cysts ...

  17. 75 FR 24434 - Federal Travel Regulation (FTR); Transportation in Conjunction With Official Travel and Relocation

    Science.gov (United States)

    2010-05-05

    ...-0010, sequence 1] RIN 3090-AJ02 Federal Travel Regulation (FTR); Transportation in Conjunction With Official Travel and Relocation AGENCY: Office of Governmentwide Policy, General Services Administration (GSA). ACTION: Final rule. SUMMARY: This final rule amends the Federal Travel Regulation (FTR), by...

  18. A process model of voluntary travel behavior modification and effects of Travel Feedback Programs (TFPs)

    OpenAIRE

    Taniguchi, Ayako

    2007-01-01

    This study tested an integrated process model of travel behavior modification. We used a model that combined the theory of planned behavior (TPB), norm activation theory (NAT), a theory of implementation intention, and theories of habit. To test the integrated model, we used panel data (n = 208) obtained before and after travel feedback programs (TFPs); the TFP is a communication program aimed at voluntary travel behavior modification, from automobile use to non-auto means of travel such as p...

  19. End to End Travel

    Data.gov (United States)

    US Agency for International Development — E2 Solutions is a web based end-to-end travel management tool that includes paperless travel authorization and voucher document submissions, document approval...

  20. Subglottic cysts and asymmetrical subglottic narrowing on neck radiograph

    International Nuclear Information System (INIS)

    Holinger, L.D.; Torium, D.M.; Anandappa, E.C.

    1988-01-01

    The congenital subglottic hemangioma typically appears as an asymmetric subglottic narrowing or mass on frontal neck radiograph. Therefore, soft tissue neck radiography has been advocated as a definitive non-operative approach for diagnosing these lesions. However, we have noted similar asymmetric subglottic narrowing in patients with acquired subglottic cysts. These retention cysts occur following long-term intubation in the neonate. The mechanism probably involves subglottic fibrosis which obstructs glands with subsequent cyst formation. Acquired subglottic cysts typically appear as an asymmetric narrowing on frontal or lateral soft tissue neck radiographs. These lesions may produce airway compromise but are effectively treated by forceps or laser removal. Acquired subglottic cysts must be included in the differential diagnosis of asymmetric subglottic narrowing. The definitive diagnosis is made by direct laryngoscopy, not soft tissue neck radiograph. (orig.)

  1. Valuation of travel time savings for intercity travel: The Madrid-Barcelona corridor

    DEFF Research Database (Denmark)

    Roman, Concepcion; Carlos Martin, Juan; Espino, Raquel

    2014-01-01

    We derive values of travel time savings (VOT) for the Madrid-Barcelona corridor, linking the two largest cities in Spain, based on the estimation of discrete choice models among the main public transport services in the corridor: air transport, high speed rail (HSR) and bus. The new HSR alternative...... (which started to operate in February 2008) competes directly with one of the densest airline domestic markets in the world, and its introduction produced substantial improvements in level of service, achieving reductions in travel time of more than 50% over the conventional train. A specifically...... to provide useful information to quantify users' benefits during the lifespan of a given project. We found, as expected, that HSR and air transport users exhibit substantially higher values for saving travel time than bus travellers. Also as expected, savings of waiting time are more valued than savings...

  2. Intercity Travel Demand Analysis Model

    Directory of Open Access Journals (Sweden)

    Ming Lu

    2014-01-01

    Full Text Available It is well known that intercity travel is an important component of travel demand which belongs to short distance corridor travel. The conventional four-step method is no longer suitable for short distance corridor travel demand analysis for the time spent on urban traffic has a great impact on traveler's main mode choice. To solve this problem, the author studied the existing intercity travel demand analysis model, then improved it based on the study, and finally established a combined model of main mode choice and access mode choice. At last, an integrated multilevel nested logit model structure system was built. The model system includes trip generation, destination choice, and mode-route choice based on multinomial logit model, and it achieved linkage and feedback of each part through logsum variable. This model was applied in Shenzhen intercity railway passenger demand forecast in 2010 as a case study. As a result, the forecast results were consistent with the actuality. The model's correctness and feasibility were verified.

  3. Lower Bounds in the Asymmetric External Memory Model

    DEFF Research Database (Denmark)

    Jacob, Riko; Sitchinava, Nodari

    2017-01-01

    Motivated by the asymmetric read and write costs of emerging non-volatile memory technologies, we study lower bounds for the problems of sorting, permuting and multiplying a sparse matrix by a dense vector in the asymmetric external memory model (AEM). Given an AEM with internal (symmetric) memory...... of size M, transfers between symmetric and asymmetric memory in blocks of size B and the ratio ω between write and read costs, we show Ω(min (N, ωN/B logω M/B N/B) lower bound for the cost of permuting N input elements. This lower bound also applies to the problem of sorting N elements. This proves...

  4. FORMS OF YOUTH TRAVEL

    OpenAIRE

    Moisã Claudia Olimpia; Moisã Claudia Olimpia

    2011-01-01

    Taking into account the suite of motivation that youth has when practicing tourism, it can be said that the youth travel takes highly diverse forms. These forms are educational tourism, volunteer programs and “work and travel”, cultural exchanges or sports tourism and adventure travel. In this article, we identified and analyzed in detail the main forms of youth travel both internationally and in Romania. We also illustrated for each form of tourism the specific tourism products targeting you...

  5. Travel and transport

    DEFF Research Database (Denmark)

    Bill, Jan; Roesdahl, Else

    2007-01-01

    On the interrelationship between travel, transport and society; on land transport, sea and river transport, and on winter transport;  on the related technologies and their developments......On the interrelationship between travel, transport and society; on land transport, sea and river transport, and on winter transport;  on the related technologies and their developments...

  6. 41 CFR 301-70.904 - Must travelers whom we carry on Government aircraft be authorized to travel?

    Science.gov (United States)

    2010-07-01

    ... flight in which they are also traveling (i.e., being transported from point to point) are considered... carry on Government aircraft be authorized to travel? 301-70.904 Section 301-70.904 Public Contracts and Property Management Federal Travel Regulation System TEMPORARY DUTY (TDY) TRAVEL ALLOWANCES AGENCY...

  7. Travelers' diarrhea.

    Science.gov (United States)

    Barrett-Connor, E

    1973-03-01

    On the average, one-fourth of North Americans visiting developing countries experience a self-limited diarrheal illness that interferes with holiday or business activities. Recent work suggests that these episodes are caused by a small inoculum of enteropathogenic Escherichia coli which are common in the country visited and rare in the country of origin. Neither antimicrobial treatment nor anti-diarrheal agents have proven benefit once the illness has begun. Despite its frequent use, iodochlorhydroxyquin has not been shown in double blind studies to be effective as a preventive agent, and may be dangerous. The status of furazolidone for prevention of tourist diarrhea is questionable. Both neomycin sulfate and phythalylsulfathiazole have demonstrated efficacy as chemoprophylactics in Mexico. However, their use should be restricted to limited types of travel and travelers. General admonitions concerning avoidance of certain ingestibles are recommended; despite questionable value in preventing travelers' diarrhea such precautions may prevent more serious gastrointestinal illness.

  8. 8 CFR 1244.15 - Travel abroad.

    Science.gov (United States)

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Travel abroad. 1244.15 Section 1244.15... REGULATIONS TEMPORARY PROTECTED STATUS FOR NATIONALS OF DESIGNATED STATES § 1244.15 Travel abroad. (a) After... Status shall not constitute permission to travel abroad. Permission to travel may be granted by the...

  9. 49 CFR 230.76 - Piston travel.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Piston travel. 230.76 Section 230.76... Tenders Brake and Signal Equipment § 230.76 Piston travel. (a) Minimum piston travel. The minimum piston travel shall be sufficient to provide proper brake shoe clearance when the brakes are released. (b...

  10. Vehicle Routing Problem Using Genetic Algorithm with Multi Compartment on Vegetable Distribution

    Science.gov (United States)

    Kurnia, Hari; Gustri Wahyuni, Elyza; Cergas Pembrani, Elang; Gardini, Syifa Tri; Kurnia Aditya, Silfa

    2018-03-01

    The problem that is often gained by the industries of managing and distributing vegetables is how to distribute vegetables so that the quality of the vegetables can be maintained properly. The problems encountered include optimal route selection and little travel time or so-called TSP (Traveling Salesman Problem). These problems can be modeled using the Vehicle Routing Problem (VRP) algorithm with rating ranking, a cross order based crossing, and also order based mutation mutations on selected chromosomes. This study uses limitations using only 20 market points, 2 point warehouse (multi compartment) and 5 vehicles. It is determined that for one distribution, one vehicle can only distribute to 4 market points only from 1 particular warehouse, and also one such vehicle can only accommodate 100 kg capacity.

  11. Uma propriedade estrutural do problema de programação da produção flow shop permutacional com tempos de setup

    Directory of Open Access Journals (Sweden)

    João Vitor Moccellin

    2007-01-01

    Full Text Available Neste artigo apresenta-se uma propriedade estrutural do problema de programação da produção flow shop permutacional com tempos de setup das máquinas separados dos tempos de processamento das tarefas, a qual foi identificada a partir de investigações que foram realizadas sobre as características do problema. Tal propriedade fornece um limitante superior do tempo de máquina parada entre a sua preparação e o início de execução das tarefas. Utilizando a propriedade, o problema original de programação da produção com minimização do makespan pode ser resolvido de maneira heurística por meio de uma analogia com o problema assimétrico do caixeiro-viajante.This paper deals with the permutation flow shop scheduling problem with separated machine setup times. As a result of an investigation on the problem characteristics a structural property is introduced. Such a property provides an upper bound on the idle time of the machines between the setup task and the job processing. As an application of this property, the original scheduling problem with the makespan criterion can be heuristically solved by an analogy with the asymmetric traveling salesman problem.

  12. 8 CFR 244.15 - Travel abroad.

    Science.gov (United States)

    2010-01-01

    ... 8 Aliens and Nationality 1 2010-01-01 2010-01-01 false Travel abroad. 244.15 Section 244.15 Aliens... NATIONALS OF DESIGNATED STATES § 244.15 Travel abroad. (a) After the grant of Temporary Protected Status... to travel abroad. Permission to travel may be granted by the director pursuant to the Service's...

  13. Schistosomiasis in european travelers and migrants

    DEFF Research Database (Denmark)

    Lingscheid, Tilman; Kurth, Florian; Clerinx, Jan

    2017-01-01

    Schistosomiasis remains one of the most prevalent parasitic diseases worldwide and the infection is frequently found in travelers and migrants. The European Network for Tropical Medicine and Travel Health conducted a sentinel surveillance study on imported schistosomiasis between 1997 and 2010...... or antigen testing. Schistosomiasis remains a frequent infection in travelers and migrants to Europe. Travelers should be made aware of the risk of schistosomiasis infection when traveling to sub-Saharan Africa. Posttravel consultations particularly for returning expatriates are useful given the high...

  14. Accurate estimation of indoor travel times

    DEFF Research Database (Denmark)

    Prentow, Thor Siiger; Blunck, Henrik; Stisen, Allan

    2014-01-01

    The ability to accurately estimate indoor travel times is crucial for enabling improvements within application areas such as indoor navigation, logistics for mobile workers, and facility management. In this paper, we study the challenges inherent in indoor travel time estimation, and we propose...... the InTraTime method for accurately estimating indoor travel times via mining of historical and real-time indoor position traces. The method learns during operation both travel routes, travel times and their respective likelihood---both for routes traveled as well as for sub-routes thereof. InTraTime...... allows to specify temporal and other query parameters, such as time-of-day, day-of-week or the identity of the traveling individual. As input the method is designed to take generic position traces and is thus interoperable with a variety of indoor positioning systems. The method's advantages include...

  15. Pre-travel advice: an overview.

    Science.gov (United States)

    Sanford, Christopher

    2002-12-01

    The message of the pre-travel provider is necessarily paradoxic. First the provider lists a score of causes of illness and premature demise, and then states, "But it sounds like a great trip and I think you'll have fun." Pre-travel providers need to walk a fine line: they must encourage patients to be cautious but not paranoid, optimistic but realistic. This discussion is complicated further by the fact that risk reduction is not the only consideration; if it were, practitioners would advise patients to remain in the developed world and foray from their homes only to visit health clubs and the fruit-and-vegetable section of grocery stores. A tacit assumption in travel medicine is that some degree of acceptance of heightened risk is tolerated for the benefit of improved quality of life offered by travel abroad. The amount of risk that is reasonable to accept for a given benefit in quality of life yielded by travel cannot be quantified, however. Providers must render judgments on what is "reasonable" and what is not, and this complex decision is based on equal parts medical knowledge and intuition. At one extreme, mountaineers in Nepal have been found to have a 2.4% mortality rate per expedition [83,84]. The travel provider might make the reasonable decision to counsel these travelers to avoid that activity. These travelers most likely will ignore that advice, at which point the provider must endeavor to reduce risk to the extent possible. Other situations in which the provider should advise a change in itinerary or activities include counseling parents who plan to take an infant to high altitude or a pregnant woman who plans to scuba dive. If travelers remain cloistered in their hotel rooms, eating all meals from room service and watching CNN, then it could be suggested that they are overly risk-adverse and might consider foraying out of the hotel, despite the potential associated increased risks to health. Conversely, if travelers find themselves on motorcycles

  16. CARLSON WAGONLIT TRAVEL

    CERN Document Server

    CARLSON WAGONLIT TRAVEL

    2004-01-01

    CARLSON WAGONLIT TRAVEL informs you that our agency will be closed from 17 December 2004 at 16:30 until 3 January 2005 at 8:30. For all URGENT MATTERS you can contact our CARLSON WAGONLIT TRAVEL branch at WHO (Mr Pierre Plumettaz), phone: 022 788 10 65 We wish you already a Merry Christmas and a Happy New Year!

  17. Traveling with Food Allergies

    Science.gov (United States)

    ... on traveling and dining out at restaurants with food allergies. Travel Tips for the U.S. and Other Countries Get information about medications and food labeling practices in select countries. Spam Control Text: ...

  18. Ultrathin-skinned asymmetric membranes by immiscible solvents treatment

    Science.gov (United States)

    Friesen, Dwayne T.; Babcock, Walter C.

    1989-01-01

    Improved semipermeable asymmetric fluid separation membranes useful in gas, vapor and liquid separations are disclosed. The membranes are prepared by substantially filling the pores of asymmetric cellulosic semipermeable membranes having a finely porous layer on one side thereof with a water immiscible organic liquid, followed by contacting the finely porous layer with water.

  19. UNderstanding uptake of Immunisations in TravellIng aNd Gypsy communities (UNITING): a qualitative interview study.

    Science.gov (United States)

    Jackson, Cath; Dyson, Lisa; Bedford, Helen; Cheater, Francine M; Condon, Louise; Crocker, Annie; Emslie, Carol; Ireland, Lana; Kemsley, Philippa; Kerr, Susan; Lewis, Helen J; Mytton, Julie; Overend, Karen; Redsell, Sarah; Richardson, Zoe; Shepherd, Christine; Smith, Lesley

    2016-09-01

    Gypsies, Travellers and Roma (referred to as Travellers) are less likely to access health services, including immunisation. To improve immunisation rates, we need to understand what helps and hinders individuals in these communities in taking up immunisations. (1) Investigate the barriers to and facilitators of acceptability and uptake of immunisations among six Traveller communities across four UK cities; and (2) identify possible interventions to increase uptake of immunisations in these Traveller communities that could be tested in a subsequent feasibility study. Three-phase qualitative study underpinned by the social ecological model. Phase 1: interviews with 174 Travellers from six communities: Romanian Roma (Bristol); English Gypsy/Irish Traveller (Bristol); English Gypsy (York); Romanian/Slovakian Roma (Glasgow); Scottish Showpeople (Glasgow); and Irish Traveller (London). Focus on childhood and adult vaccines. Phase 2: interviews with 39 service providers. Data were analysed using the framework approach. Interventions were identified using a modified intervention mapping approach. Phase 3: 51 Travellers and 25 service providers attended workshops and produced a prioritised list of potentially acceptable and feasible interventions. There were many common accounts of barriers and facilitators across communities, particularly across the English-speaking communities. Scottish Showpeople were the most similar to the general population. Roma communities experienced additional barriers of language and being in a new country. Men, women and service providers described similar barriers and facilitators. There was widespread acceptance of childhood and adult immunisation, with current parents perceived as more positive than their elders. A minority of English-speaking Travellers worried about multiple/combined childhood vaccines, adult flu and whooping cough. Cultural concerns about vaccines offered during pregnancy and about human papillomavirus were most evident in

  20. Genetic algorithm for the optimization of the loading pattern for reactor core fuel management

    International Nuclear Information System (INIS)

    Zhou Sheng; Hu Yongming; zheng Wenxiang

    2000-01-01

    The paper discusses the application of a genetic algorithm to the optimization of the loading pattern for in-core fuel management with the NP characteristics. The algorithm develops a matrix model for the fuel assembly loading pattern. The burnable poisons matrix was assigned randomly considering the distributed nature of the poisons. A method based on the traveling salesman problem was used to solve the problem. A integrated code for in-core fuel management was formed by combining this code with a reactor physics code

  1. On One Approach to TSP Structural Stability

    Directory of Open Access Journals (Sweden)

    Evgeny Ivanko

    2014-01-01

    Full Text Available In this paper we study an inverse approach to the traveling salesman reoptimization problem. Namely, we consider the case of the addition of a new vertex to the initial TSP data and fix the simple “adaptation” algorithm: the new vertex is inserted into an edge of the optimal tour. In the paper we consider the conditions describing the vertexes that can be inserted by this algorithm without loss of optimality, study the properties of stability areas, and address several model applications.

  2. Travelers' Health: Leishmaniasis, Visceral

    Science.gov (United States)

    ... such as the United States reflects travel and immigration patterns. VL is uncommon in US travelers and ... whqlibdoc.who.int/trs/WHO_TRS_949_eng.pdf . Chapter 3 - Leishmaniasis, Cutaneous Chapter 3 - Leptospirosis File ...

  3. Asymmetric conditional volatility in international stock markets

    Science.gov (United States)

    Ferreira, Nuno B.; Menezes, Rui; Mendes, Diana A.

    2007-08-01

    Recent studies show that a negative shock in stock prices will generate more volatility than a positive shock of similar magnitude. The aim of this paper is to appraise the hypothesis under which the conditional mean and the conditional variance of stock returns are asymmetric functions of past information. We compare the results for the Portuguese Stock Market Index PSI 20 with six other Stock Market Indices, namely the SP 500, FTSE 100, DAX 30, CAC 40, ASE 20, and IBEX 35. In order to assess asymmetric volatility we use autoregressive conditional heteroskedasticity specifications known as TARCH and EGARCH. We also test for asymmetry after controlling for the effect of macroeconomic factors on stock market returns using TAR and M-TAR specifications within a VAR framework. Our results show that the conditional variance is an asymmetric function of past innovations raising proportionately more during market declines, a phenomenon known as the leverage effect. However, when we control for the effect of changes in macroeconomic variables, we find no significant evidence of asymmetric behaviour of the stock market returns. There are some signs that the Portuguese Stock Market tends to show somewhat less market efficiency than other markets since the effect of the shocks appear to take a longer time to dissipate.

  4. Additive measures of travel time variability

    DEFF Research Database (Denmark)

    Engelson, Leonid; Fosgerau, Mogens

    2011-01-01

    This paper derives a measure of travel time variability for travellers equipped with scheduling preferences defined in terms of time-varying utility rates, and who choose departure time optimally. The corresponding value of travel time variability is a constant that depends only on preference...... parameters. The measure is unique in being additive with respect to independent parts of a trip. It has the variance of travel time as a special case. Extension is provided to the case of travellers who use a scheduled service with fixed headway....

  5. Salt supply to and significance of asymmetric salt diapirs

    DEFF Research Database (Denmark)

    Koyi, H.; Burliga, S.; Chemia, Zurab

    2012-01-01

    Salt diapirs can be asymmetric both internally and externally reflecting their evolution history. As such, this asymmetry bear a significant amount of information about the differential loading (± lateral forces) and in turn the salt supply that have shaped the diapir. In two dimensions......, In this study we compare results of analogue and numerical models of diapirs with two natural salt diapris (Klodawa and Gorleben diapirs) to explain their salt supply and asymmetric evolution. In a NW-SE section, the Gorleben salt diapir possesses an asymmetric external geometry represented by a large...... southeastern overhang due to salt extrusion during Middle Cretaceous followed by its burial in Tertiary. This external asymmetry is also reflected in the internal configuration of the diapir which shows different rates of salt flow on the two halves of the structure. The asymmetric external and internal...

  6. Two-channel totally asymmetric simple exclusion processes

    International Nuclear Information System (INIS)

    Pronina, Ekaterina; Kolomeisky, Anatoly B

    2004-01-01

    Totally asymmetric simple exclusion processes, consisting of two coupled parallel lattice chains with particles interacting with hard-core exclusion and moving along the channels and between them, are considered. In the limit of strong coupling between the channels, the particle currents, density profiles and a phase diagram are calculated exactly by mapping the system into an effective one-channel totally asymmetric exclusion model. For intermediate couplings, a simple approximate theory, that describes the particle dynamics in vertical clusters of two corresponding parallel sites exactly and neglects the correlations between different vertical clusters, is developed. It is found that, similarly to the case of one-channel totally asymmetric simple exclusion processes, there are three stationary state phases, although the phase boundaries and stationary properties strongly depend on inter-channel coupling. Extensive computer Monte Carlo simulations fully support the theoretical predictions

  7. Valuation of travel time for international long-distance travel - results from the Fehmarn Belt stated choice experiment

    DEFF Research Database (Denmark)

    Mabit, Stefan Lindhard; Rich, Jeppe; Burge, Peter

    2013-01-01

    of travel time savings (VTTS). The final model, which was formulated as a nested logit model and included Box–Cox transformed travel time and cost attributes, revealed several interesting findings. Firstly, we found damping effects in both cost and time – most strongly in cost. Secondly, we found...... significant interactions among travel cost and time, and journey characteristics, such as distance and duration. This had direct impact on the VTTS, which was shown to decrease with distance and duration. Thirdly, we found that air travel implies a higher average VTTS, which is to be expected but rarely......The geographical scope of travel varies from short distances in urban areas to long distances across cities and countries. While urban travel has been widely analysed in the literature, travel over longer distances and particularly across countries, has received much less attention. While this may...

  8. Traveling Safely with Medicines

    Science.gov (United States)

    ... Medications Safely My Medicine List How to Administer Traveling Safely with Medicines Planes, trains, cars – even boats ... your trip, ask your pharmacist about how to travel safely with your medicines. Make sure that you ...

  9. Appropriate quantization of asymmetric games with continuous strategies

    International Nuclear Information System (INIS)

    Qin Gan; Chen Xi; Sun Min; Zhou Xianyi; Du Jiangfeng

    2005-01-01

    We establish a new quantization scheme to study the asymmetric Bertrand duopoly with differentiated products. This scheme is more efficient than the previous symmetric one because it can exactly make the optimal cooperative payoffs at quantum Nash equilibrium. It is also a necessary condition for general asymmetric games with continuous strategies to reach such payoffs

  10. Estimating Household Travel Energy Consumption in Conjunction with a Travel Demand Forecasting Model

    Energy Technology Data Exchange (ETDEWEB)

    Garikapati, Venu M. [Systems Analysis and Integration Section, National Renewable Energy Laboratory, 15013 Denver West Parkway, Golden, CO 80401; You, Daehyun [Maricopa Association of Governments, 302 North First Avenue, Suite 300, Phoenix, AZ 85003; Zhang, Wenwen [School of City and Regional Planning, Center for Geographic Information Systems, Georgia Institute of Technology, 760 Spring Street, Suite 230, Atlanta, GA 30308; Pendyala, Ram M. [School of Sustainable Engineering and the Built Environment, Arizona State University, 660 South College Avenue, Tempe, AZ 85281; Guhathakurta, Subhrajit [School of City and Regional Planning, Center for Geographic Information Systems, Georgia Institute of Technology, 760 Spring Street, Suite 230, Atlanta, GA 30308; Brown, Marilyn A. [School of Public Policy, 685 Cherry Street, Georgia Institute of Technology, Atlanta, GA 30332; Dilkina, Bistra [School of Computational Science and Engineering, 266 Ferst Drive, Georgia Institute of Technology, Atlanta, GA 30332

    2017-01-01

    This paper presents a methodology for the calculation of the consumption of household travel energy at the level of the traffic analysis zone (TAZ) in conjunction with information that is readily available from a standard four-step travel demand model system. This methodology embeds two algorithms. The first provides a means of allocating non-home-based trips to residential zones that are the source of such trips, whereas the second provides a mechanism for incorporating the effects of household vehicle fleet composition on fuel consumption. The methodology is applied to the greater Atlanta, Georgia, metropolitan region in the United States and is found to offer a robust mechanism for calculating the footprint of household travel energy at the level of the individual TAZ; this mechanism makes possible the study of variations in the energy footprint across space. The travel energy footprint is strongly correlated with the density of the built environment, although socioeconomic differences across TAZs also likely contribute to differences in travel energy footprints. The TAZ-level calculator of the footprint of household travel energy can be used to analyze alternative futures and relate differences in the energy footprint to differences in a number of contributing factors and thus enables the design of urban form, formulation of policy interventions, and implementation of awareness campaigns that may produce more-sustainable patterns of energy consumption.

  11. [Travel medicine for HIV-infected patients].

    Science.gov (United States)

    Rossi, M; Furrer, H

    2001-06-01

    Many HIV-infected persons travel from temperate zones to (sub)tropical destinations. HIV-specific immigration issues, medical resources abroad and problems regarding travelling with multiple medications have to be anticipated. When prescribing immunizations and specific chemoprophylaxis, the stage of immunodeficiency as well as drug interactions with antiretrovirals and medicaments against opportunistic infections have to be taken into account. Live vaccines may be contraindicated. Immunocompromised HIV-infected travellers have a higher risk for serious courses of diseases by enteropathogens. Therefore a good information about food hygiene is important and a prescription of an antibiotic to take in case of severe diarrhea may be indicated. A new antiretroviral combination therapy should not be started immediately before travelling to the tropics. The possibility to continue an established HIV treatment during travel has to be evaluated cautiously. With good pre-travel advice the risk of severe health problems is low for most HIV-infected travellers.

  12. Asymmetric forecasting and commitment policy in a robust control problem

    OpenAIRE

    Taro Ikeda

    2013-01-01

    This paper provides a piece of results regarding asymmetric forecasting and commitment monetary policy with a robust control algorithm. Previous studies provide no clarification of the connection between asymmetric preference and robust commitment policy. Three results emerge from general equilibrium modeling with asymmetric preference: (i) the condition for system stability implies an average inflation bias with respect to asymmetry (ii) the effect of asymmetry can be mitigated if policy mak...

  13. Experienced travel time prediction for congested freeways

    OpenAIRE

    Yildirimoglu, Mehmet; Geroliminis, Nikolaos

    2013-01-01

    Travel time is an important performance measure for transportation systems, and dissemination of travel time information can help travelers make reliable travel decisions such as route choice or departure time. Since the traffic data collected in real time reflects the past or current conditions on the roadway, a predictive travel time methodology should be used to obtain the information to be disseminated. However, an important part of the literature either uses instantaneous travel time ass...

  14. Impact of Secondary Interactions in Asymmetric Catalysis

    OpenAIRE

    Frölander, Anders

    2007-01-01

    This thesis deals with secondary interactions in asymmetric catalysis and their impact on the outcome of catalytic reactions. The first part revolves around the metal-catalyzed asymmetric allylic alkylation reaction and how interactions within the catalyst affect the stereochemistry. An OH–Pd hydrogen bond in Pd(0)–π-olefin complexes of hydroxy-containing oxazoline ligands was identified by density functional theory computations and helped to rationalize the contrasting results obtained emplo...

  15. How Is Nature Asymmetric?

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 7; Issue 6. How Is Nature Asymmetric? - Discrete Symmetries in Particle Physics and their Violation ... Indian Institute of Technology, Chennai. Aligarh Muslim University. University of Rajasthan, Jaipur. Indian Institute of Science, Bangalore 560012, India.

  16. Exploring asymmetric catalytic transformations

    NARCIS (Netherlands)

    Guduguntla, Sureshbabu

    2017-01-01

    In Chapter 2, we report a highly enantioselective synthesis of β-alkyl-substituted alcohols through a one-pot Cu- catalyzed asymmetric allylic alkylation with organolithium reagents followed by reductive ozonolysis. The synthesis of γ-alkyl-substituted alcohols was also achieved through Cu-catalyzed

  17. Simulation of Phenix EOL Asymmetric Test

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Kwi Seok; Lee, Kwi Lim; Choi, Chi Woong; Kang, Seok Hun; Chang, Won Pyo; Jeong, Hae Yong [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2012-05-15

    The asymmetric test of End-Of-Life (EOL) tests on the Phenix plant was used for the evaluation of the MARS-LMR in the Generation IV frame as a part of the code validation. The purpose of the test is to evaluate the ability of the system code to describe asymmetric situations and to identify important phenomena during asymmetrical transient such as a three dimensional effect, buoyancy influence, and thermal stratification in the hot and cold pools. 3-dimensional sodium coolant mixing in the pools has different characteristics from the one dimensional full instantaneous mixing. The velocities and temperatures at the core outlet level differ at each sub-assembly and the temperature in the center of the hot pool may be high because the driver fuels are located at the center region. The temperatures in the hot pool are not the same in the radial and axial locations due to the buoyancy effect. The temperatures in the cold pool also differ along with the elevations and azimuthal directions due to the outlet location of IHX and the thermal stratification

  18. Flatfish: an asymmetric perspective on metamorphosis.

    Science.gov (United States)

    Schreiber, Alexander M

    2013-01-01

    The most asymmetrically shaped and behaviorally lateralized of all the vertebrates, the flatfishes are an endless source of fascination to all fortunate enough to study them. Although all vertebrates undergo left-right asymmetric internal organ placement during embryogenesis, flatfish are unusual in that they experience an additional period of postembryonic asymmetric remodeling during metamorphosis, and thus deviate from a bilaterally symmetrical body plan more than other vertebrates. As with amphibian metamorphosis, all the developmental programs of flatfish metamorphosis are ultimately under the control of thyroid hormone. At least one gene pathway involved in embryonic organ lateralization (nodal-lefty-pitx2) is re-expressed in the larval stage during flatfish metamorphosis. Aspects of modern flatfish ontogeny, such as the gradual translocation of one eye to the opposite side of the head and the appearance of key neurocranial elements during metamorphosis, seem to elegantly recapitulate flatfish phylogeny. This chapter highlights the current state of knowledge of the developmental biology of flatfish metamorphosis with emphases on the genetic, morphological, behavioral, and evolutionary origins of flatfish asymmetry. Copyright © 2013 Elsevier Inc. All rights reserved.

  19. Skin disorders among travellers returning from tropical and non-tropical countries consulting a travel medicine clinic.

    Science.gov (United States)

    Herbinger, K-H; Siess, C; Nothdurft, H D; von Sonnenburg, F; Löscher, T

    2011-11-01

    To evaluate the causes and risks for imported skin disorders among travellers. Data of 34,162 travellers returning from tropical and non-tropical countries and presenting at the outpatient travel medicine clinic of the University of Munich, Germany, between 1999 and 2009 were analyzed for this study. Of these, 12.2% were diagnosed with skin disorders. Main destinations visited were Asia (40%), Africa (27%) and Latin America (21%). Tourism in the form of adventure travel/backpacking (47%) and package holidays (23%) was the most common purpose of travel. The leading causes of skin disorders were arthropodal (23%), bacterial (22%), helminthic (11%), protozoan (6%), viral (6%), allergic (5%) and fungal (4%). The 10 most frequently diagnosed specific skin diseases associated with specific destinations were insect bites (17%, Southern Europe), cutaneous larva migrans (8%, Asia and Latin America), cutaneous leishmaniasis (2.4%, Mediterranean Region/Middle East), dengue fever (1.5%, Asia), rickettsioses (1.3%, Southern Africa), myiasis (0.8%, Central America), filarioses (0.7%, Africa), tick bites (0.6%, Central/Eastern Europe), schistosomiasis (0.6%, Africa) and tungiasis (0.6%, Africa). Travellers in sub-Saharan Africa had the highest relative risk of acquiring skin disorders. As more than 20% of all skin disorders among returned travellers were caused by arthropods and about 50% by infectious pathogens, pre-travel consultations should include specific prophylaxis and consider the most important risk factor for the travel destination. © 2011 Blackwell Publishing Ltd.

  20. Self-reported infections during international travel and notifiable infections among returning international travellers, Sweden, 2009-2013.

    Directory of Open Access Journals (Sweden)

    Viktor Dahl

    Full Text Available We studied food and water-borne diseases (FWDs, sexually transmitted diseases (STDs, vector-borne diseases (VBDs and diseases vaccinated against in the Swedish childhood vaccination programme among Swedish international travellers, in order to identify countries associated with a high number of infections. We used the national database for notifiable infections to estimate the number of FWDs (campylobacteriosis, salmonellosis, giardiasis, shigellosis, EHEC, Entamoeba histolytica, yersinosis, hepatitis A, paratyphoid fever, typhoid fever, hepatitis E, listeriosis, cholera, STIs (chlamydia, gonorrhoea and acute hepatitis B, VBDs (dengue fever, malaria, West Nile fever, Japanese encephalitis and yellow fever and diseases vaccinated against in the Swedish childhood vaccination programme (pertussis, measles, mumps, rubella, diphtheria acquired abroad 2009-2013. We obtained number and duration of trips to each country from a database that monthly collects travel data from a randomly selected proportion of the Swedish population. We calculated number of infections per country 2009-2013 and incidence/million travel days for the five countries with the highest number of infections. Thailand had the highest number of FWDs (7,697, incidence 191/million travel days, STIs (1,388, incidence 34/million travel days and VBDs (358, incidence 9/million travel days. France had the highest number of cases of diseases vaccinated against in the Swedish childhood vaccination programme (8, 0.4/million travel days. Swedish travellers contracted most infections in Thailand. Special focus should be placed on giving advice to travellers to this destination.

  1. Infectious Risks of Traveling Abroad.

    Science.gov (United States)

    Chen, Lin H; Blair, Barbra M

    2015-08-01

    A popular leisure activity, international travel can be associated with some infections. The most common travel-related illnesses appear to be gastrointestinal, dermatologic, respiratory, and systemic febrile syndromes. The pretravel medical consultation includes immunizations, malaria chemoprophylaxis, self-treatment for traveler's diarrhea, and advice on the prevention of a myriad of other infectious causes including dengue, chikungunya, rickettsiosis, leptospirosis, schistosomiasis, and strongyloidiasis. Travel to locations experiencing outbreaks such as Ebola virus disease, Middle East respiratory syndrome, avian influenza, and chikungunya call for specific alerts on preventive strategies. After travel, evaluation of an ill traveler must explore details of exposure, including destinations visited; activities; ingestion of contaminated food or drinks; contact with vectors, animals, fresh water, or blood and body fluids; and other potential exposures. Knowledge of the geographic distribution of infectious diseases is important in generating the differential diagnoses and testing accordingly. Empiric treatment is sometimes necessary when suspicion of a certain diagnosis is strong and confirmatory tests are delayed or lacking, particularly for infections that are rapidly progressive (for example, malaria) or for which timing of testing is prolonged (such as leptospirosis).

  2. Post-harmonised European National Travel Surveys

    DEFF Research Database (Denmark)

    Christensen, Linda; Sobrino Vázquez, Natalia

    Look-up tables are collected and analysed for 12 European National Travel Surveys (NTS) in a harmonized way covering the age group 13-84 year. Travel behaviour measured as kilometres, time use and trips per traveller is compared. Trips per traveller are very similar over the countries whereas...... of walking trips rather similar with a higher level of cycling in the Netherlands, more public transport in Switzerland, and more air traffic in Sweden. Normally kilometres per respondent / inhabitant is used for national planning purpose and this is very affected by the share of mobile travellers...

  3. Pre-Travel Medical Preparation of Business and Occupational Travelers: An Analysis of the Global TravEpiNet Consortium, 2009 to 2012.

    Science.gov (United States)

    Khan, Nomana M; Jentes, Emily S; Brown, Clive; Han, Pauline; Rao, Sowmya R; Kozarsky, Phyllis; Hagmann, Stefan H F; LaRocque, Regina C; Ryan, Edward T

    2016-01-01

    The aim of the study was to understand more about pre-travel preparations and itineraries of business and occupational travelers. De-identified data from 18 Global TravEpiNet clinics from January 2009 to December 2012 were analyzed. Of 23,534 travelers, 61% were non-occupational and 39% occupational. Business travelers were more likely to be men, had short times to departure and shorter trip durations, and commonly refused influenza, meningococcal, and hepatitis B vaccines. Most business travelers indicated that employers suggested the pre-travel health consultation, whereas non-occupational travelers sought consultations because of travel health concerns. Sub-groups of occupational travelers have characteristic profiles, with business travelers being particularly distinct. Employers play a role in encouraging business travelers to seek pre-travel consultations. Such consultations, even if scheduled immediately before travel, can identify vaccination gaps and increase coverage.

  4. Standards vs. labels with imperfect competition and asymmetric information

    DEFF Research Database (Denmark)

    Baltzer, Kenneth Thomas

    2012-01-01

    I demonstrate that providing information about product quality is not necessarily the best way to address asymmetric information problems when markets are imperfectly competitive. In a vertical differentiation model I show that a Minimum Quality Standard, which retains asymmetric information...

  5. Standards vs. labels with imperfect competition and asymmetric information

    DEFF Research Database (Denmark)

    Baltzer, Kenneth Thomas

    I demonstrate that providing information about product quality is not necessarily the best way to address asymmetric information problems when markets are imperfectly competitive. In a vertical dierentiation model I show that a Minimum Quality Standard, which retains asymmetric information...

  6. 5 CFR 550.1404 - Creditable travel time.

    Science.gov (United States)

    2010-01-01

    ... 5 Administrative Personnel 1 2010-01-01 2010-01-01 false Creditable travel time. 550.1404 Section... ADMINISTRATION (GENERAL) Compensatory Time Off for Travel § 550.1404 Creditable travel time. (a) General. Subject... off for time in a travel status if— (1) The employee is required to travel away from the official duty...

  7. CARLSON WAGONLIT TRAVEL

    CERN Multimedia

    2006-01-01

    CARLSON WAGONLIT TRAVEL informs you that our agency will be closed from 22 December 2006 at 16:30 until 8 January 2007 at 8:30. For all URGENT MATTERS you can contact our CARLSON WAGONLIT TRAVEL branch at W.H.O. (Mr Pierre Plumettaz), phone: 022 791 55 95. We wish you already a Merry Christmas and a Happy New Year!

  8. Recommended vaccines for international travelers to India.

    Science.gov (United States)

    Verma, Ramesh; Khanna, Pardeep; Chawla, Suraj

    2015-01-01

    India's tourism industry generated 6.6% of the nation's Gross Domestic Product (GDP) during 2012. International travel to India is predicted to grow at an average annual rate of ∼ 8% over the next decade. The number of foreign tourists has increased by 9% to 5.8 million. Approximately 8% of travelers to developing countries require medical care during or after travel; the main diagnoses are vaccine-preventable diseases. Travelers to India can be exposed to various infectious diseases; water-borne, water-related, and zoonotic diseases may be imported to India where the disease is not endemic. The World Health Organization (WHO) emphasizes that all international travelers should be up to date with routine vaccinations. The recommended vaccinations for travelers to India vary according to the traveler's age, immunization history, existing medical conditions, duration, legal requirements for entry into countries being visited, travelers preferences, and values. Travelers should consult with a doctor so that there is sufficient time for completion of optimal vaccination schedules. No matter where traveling, one should be aware of potential exposure to certain organisms that can cause severely illnesses, even death. There is no doubt that vaccines have reduced or virtually eliminated many diseases that killed or severely disabled children and adults just a few generations ago. Thus, travelers must take recommended vaccines per schedule before traveling to India.

  9. U.S. business travel

    Science.gov (United States)

    2003-10-01

    Americans make more than 405 million long-distance business trips per year, : accounting for 16% of all long-distance travel, according to a : preliminary analysis of the National Household Travel Survey (NHTS). : Conducted from 2001 to 2002, the NHT...

  10. Asymmetrical Polymer Vesicles for Drug delivery and Other Applications

    Directory of Open Access Journals (Sweden)

    Yi Zhao

    2017-06-01

    Full Text Available Scientists have been attracted by polymersomes as versatile drug delivery systems since the last two decades. Polymersomes have the potential to be versatile drug delivery systems because of their tunable membrane formulations, stabilities in vivo, various physicochemical properties, controlled release mechanisms, targeting abilities, and capacities to encapsulate a wide range of drugs and other molecules. Asymmetrical polymersomes are nano- to micro-sized polymeric capsules with asymmetrical membranes, which means, they have different outer and inner coronas so that they can exhibit better endocytosis rate and endosomal escape ability than other polymeric systems with symmetrical membranes. Hence, asymmetrical polymersomes are highly promising as self-assembled nano-delivery systems in the future for in vivo therapeutics delivery and diagnostic imaging applications. In this review, we prepared a summary about recent research progresses of asymmetrical polymersomes in the following aspects: synthesis, preparation, applications in drug delivery and others.

  11. Periodic travelling and non-travelling wave solutions of the nonlinear Klein-Gordon equation with imaginary mass

    International Nuclear Information System (INIS)

    Tang Xiaoyan; Shukla, Padma Kant

    2008-01-01

    Exact solutions, including the periodic travelling and non-travelling wave solutions, are presented for the nonlinear Klein-Gordon equation with imaginary mass. Some arbitrary functions are permitted in the periodic non-travelling wave solutions, which contribute to various high dimensional nonlinear structures

  12. Travel Mode Use, Travel Mode Shift and Subjective Well-Being: Overview of Theories, Empirical Findings and Policy Implications

    NARCIS (Netherlands)

    Ettema, D.F.; Friman, M.; Gärling, Tommy; Olsson, Lars

    2016-01-01

    This chapter discusses how travel by different travel modes is related to primarily subjective well-being but also to health or physical well-being. Studies carried out in different geographic contexts consistently show that satisfaction with active travel modes is higher than travel by car and

  13. 38 CFR 60.5 - Travel.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 2 2010-07-01 2010-07-01 false Travel. 60.5 Section 60.5... TEMPORARY LODGING § 60.5 Travel. As a condition for receiving temporary lodging under this part, a veteran must be required to travel either 50 or more miles, or at least two hours from his or her home to the...

  14. Dynamic analysis of holiday travel behavior with integrated multimodal travel information usage : a life-oriented approach

    NARCIS (Netherlands)

    Wang, B.; Shao, C.; Ji, X.

    2017-01-01

    The Integrated Multimodal Travel Information (IMTI) plays an important role in the evolution process of holiday travel behaviour, which is seldom investigated. To fill this gap, this study analyses holiday travel behaviour dynamics with IMTI usage, based on the life-oriented approach. IMTI usage is

  15. Pre-travel preparation practices among business travellers to tropical and subtropical destinations: results from the Athens International Airport Survey.

    Science.gov (United States)

    Pavli, Androula; Silvestros, Chrysovalantis; Patrinos, Stavros; Lymperi, Ioanna; Maltezou, Helena C

    2014-01-01

    The number of business travellers from Greece to tropical and subtropical areas has recently increased. The study aimed to assess travel health preparation practices of business travellers departing to Africa, the Middle East and Asia. A questionnaire-based survey was conducted at Athens International Airport, from 1st of November 2011 to 30th of April 2013. A total of 684 business travellers participated in the study; the majority were men (86.1%), of Greek nationality (95.3%), with tertiary education (90.8%) and employed (98%). Their mean age was 40 years; 62% and 26% of them were 35-49 and 19-34 years of age respectively. 84.8% were travelling alone. Most frequent destinations were the Middle East (46.8%) and sub-Saharan Africa (16%). For 23.5% of the travellers it was their first trip to a tropical or subtropical country. Only 58.8% pursued pre-travel health consultation; vaccination and malaria chemoprophylaxis were administered to 24.7% and 25.7% of the travellers, respectively. Hepatitis A and typhoid vaccination rates were lower than expected (70% and 35%, respectively). Nearly half of the travellers who visited malaria endemic areas did not receive any chemoprophylaxis. Having elementary education level, travelling to the Middle East or North Africa, travelling for less than 1 month duration, and staying in a house or a hotel were associated with a higher probability of not pursuing health consultation. Significant gaps were found in pre-travel health practices of business travellers departing to Africa, the Middle East and Asia. Strategies should be developed in order to improve awareness of business travellers. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. ADAPTIVE SELECTION OF AUXILIARY OBJECTIVES IN MULTIOBJECTIVE EVOLUTIONARY ALGORITHMS

    Directory of Open Access Journals (Sweden)

    I. A. Petrova

    2016-05-01

    Full Text Available Subject of Research.We propose to modify the EA+RL method, which increases efficiency of evolutionary algorithms by means of auxiliary objectives. The proposed modification is compared to the existing objective selection methods on the example of travelling salesman problem. Method. In the EA+RL method a reinforcement learning algorithm is used to select an objective – the target objective or one of the auxiliary objectives – at each iteration of the single-objective evolutionary algorithm.The proposed modification of the EA+RL method adopts this approach for the usage with a multiobjective evolutionary algorithm. As opposed to theEA+RL method, in this modification one of the auxiliary objectives is selected by reinforcement learning and optimized together with the target objective at each step of the multiobjective evolutionary algorithm. Main Results.The proposed modification of the EA+RL method was compared to the existing objective selection methods on the example of travelling salesman problem. In the EA+RL method and its proposed modification reinforcement learning algorithms for stationary and non-stationary environment were used. The proposed modification of the EA+RL method applied with reinforcement learning for non-stationary environment outperformed the considered objective selection algorithms on the most problem instances. Practical Significance. The proposed approach increases efficiency of evolutionary algorithms, which may be used for solving discrete NP-hard optimization problems. They are, in particular, combinatorial path search problems and scheduling problems.

  17. How urban environment affects travel behavior? Integrated Choice and Latent Variable Model for Travel Schedules

    DEFF Research Database (Denmark)

    La Paix, Lissy; Bierlaire, Michel; Cherchi, Elisabetta

    2013-01-01

    The relationship between urban environment and travel behaviour is not a new problem. Neighbourhood characteristics may affect mobility of dwellers in different ways, such as frequency of trips, mode used, structure of the tours, and so on. At the same time, qualitative issues related...... to the individual attitude towards specific behaviour have recently become important in transport modelling contributing to a better understanding of travel demand. Following this research line, in this paper we study the effect of neighbourhood characteristics in the choice of the type of tours performed, but we...... assume that neighbourhood characteristics can also affect the individual propensity to travel and hence the choice of the tours throughout the propensity to travel. Since the propensity to travel is not observed, we employ hybrid choice models to estimate jointly the discrete choice of tours...

  18. Vaccination for the expatriate and long-term traveler.

    Science.gov (United States)

    Shepherd, Suzanne M; Shoff, William H

    2014-06-01

    Duration of travel is an important factor in addressing travel health safety due to cumulative risk of exposure to illness and injury. The diverse group of expatriate and long-term business and leisure travelers present a different spectrum of issues for the travel medicine practitioner to address during consultation than does the short-term traveler, due to changes in travel patterns and activities, lifestyle alterations, and increased interaction with local populations. Immunization provides one safe and reliable method of preventing infectious illness in this group. We review travel patterns and available data on illnesses that they may be exposed to, including the increased risk of certain vaccine-preventable illnesses. We review the pre-travel management of these travelers, particularly the increased risk of certain vaccine-preventable illnesses as it applies to routine vaccines, recommended travel vaccines and required travel vaccines.

  19. Solving the Traveling Salesman’s Problem Using the African Buffalo Optimization

    Directory of Open Access Journals (Sweden)

    Julius Beneoluchi Odili

    2016-01-01

    Full Text Available This paper proposes the African Buffalo Optimization (ABO which is a new metaheuristic algorithm that is derived from careful observation of the African buffalos, a species of wild cows, in the African forests and savannahs. This animal displays uncommon intelligence, strategic organizational skills, and exceptional navigational ingenuity in its traversal of the African landscape in search for food. The African Buffalo Optimization builds a mathematical model from the behavior of this animal and uses the model to solve 33 benchmark symmetric Traveling Salesman’s Problem and six difficult asymmetric instances from the TSPLIB. This study shows that buffalos are able to ensure excellent exploration and exploitation of the search space through regular communication, cooperation, and good memory of its previous personal exploits as well as tapping from the herd’s collective exploits. The results obtained by using the ABO to solve these TSP cases were benchmarked against the results obtained by using other popular algorithms. The results obtained using the African Buffalo Optimization algorithm are very competitive.

  20. Value of travel time.

    Science.gov (United States)

    2016-08-01

    Knowingly or not, people generally place economic value on their time. Wage workers are paid a rate per hour, and service providers may charge per hour of their time. In the transportation realm, travelers place a value on their travel time and have ...