A Study of Driver’s Route Choice Behavior Based on Evolutionary Game Theory

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Xiaowei Jiang

2014-01-01

Full Text Available This paper proposes a route choice analytic method that embeds cumulative prospect theory in evolutionary game theory to analyze how the drivers adjust their route choice behaviors under the influence of the traffic information. A simulated network with two alternative routes and one variable message sign is built to illustrate the analytic method. We assume that the drivers in the transportation system are bounded rational, and the traffic information they receive is incomplete. An evolutionary game model is constructed to describe the evolutionary process of the drivers’ route choice decision-making behaviors. Here we conclude that the traffic information plays an important role in the route choice behavior. The driver’s route decision-making process develops towards different evolutionary stable states in accordance with different transportation situations. The analysis results also demonstrate that employing cumulative prospect theory and evolutionary game theory to study the driver’s route choice behavior is effective. This analytic method provides an academic support and suggestion for the traffic guidance system, and may optimize the travel efficiency to a certain extent.

Meta-analysis of choice set generation effects on route choice model estimates and predictions

DEFF Research Database (Denmark)

Prato, Carlo Giacomo

2012-01-01

are applied for model estimation and results are compared to the ‘true model estimates’. Last, predictions from the simulation of models estimated with objective choice sets are compared to the ‘postulated predicted routes’. A meta-analytical approach allows synthesizing the effect of judgments......Large scale applications of behaviorally realistic transport models pose several challenges to transport modelers on both the demand and the supply sides. On the supply side, path-based solutions to the user assignment equilibrium problem help modelers in enhancing the route choice behavior...... modeling, but require them to generate choice sets by selecting a path generation technique and its parameters according to personal judgments. This paper proposes a methodology and an experimental setting to provide general indications about objective judgments for an effective route choice set generation...

Husbands' return migration and wives' occupational choices

NARCIS (Netherlands)

Mahe, Clotilde

2017-01-01

Exploiting the documented effect of migration on occupational choice upon return to their origin country with data from Egypt, we establish a link between return migration of men and their wives' time use through within-couple occupational interdependence. Seemingly Unrelated Regression model

Air Cargo Transportation Route Choice Analysis

Science.gov (United States)

Obashi, Hiroshi; Kim, Tae-Seung; Oum, Tae Hoon

2003-01-01

Using a unique feature of air cargo transshipment data in the Northeast Asian region, this paper identifies the critical factors that determine the transshipment route choice. Taking advantage of the variations in the transport characteristics in each origin-destination airports pair, the paper uses a discrete choice model to describe the transshipping route choice decision made by an agent (i.e., freight forwarder, consolidator, and large shipper). The analysis incorporates two major factors, monetary cost (such as line-haul cost and landing fee) and time cost (i.e., aircraft turnaround time, including loading and unloading time, custom clearance time, and expected scheduled delay), along with other controls. The estimation method considers the presence of unobserved attributes, and corrects for resulting endogeneity by use of appropriate instrumental variables. Estimation results find that transshipment volumes are more sensitive to time cost, and that the reduction in aircraft turnaround time by 1 hour would be worth the increase in airport charges by more than $1000. Simulation exercises measures the impacts of alternative policy scenarios for a Korean airport, which has recently declared their intention to be a future regional hub in the Northeast Asian region. The results suggest that reducing aircraft turnaround time at the airport be an effective strategy, rather than subsidizing to reduce airport charges.

La 72: an oasis along the migration routes in Mexico

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Alejandro Olayo-Méndez

2017-10-01

Full Text Available Locally run shelters along the migration routes in Mexico provide sorely needed respite and support. In the face of violence, stricter migration policies and daily obstacles, those working at the La 72 shelter strive to respect people’s sense of dignity while caring for their safety.

Analysis of inertial choice behaviour based expected and experienced savings from a real-world route choice experiment

NARCIS (Netherlands)

Vreeswijk, J.D.; Rakha, H.; Van Berkum, E.; Van Arem, B.

2014-01-01

In the context of route choice, inertial behaviour shows that drivers make choices that are satisfactory rather than optimal. Consequently, drivers may not necessarily alter their choice when confronted with a travel time increase on the current choice or a travel time decrease of a choice

Modeling route choice criteria from home to major streets: A discrete choice approach

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Jose Osiris Vidana-Bencomo

2018-03-01

Full Text Available A discrete choice model that consists of three sub-models was developed to investigates the route choice criteria of drivers who travel from their homes in the morning to the access point along the major streets that bound the Traffic Analysis Zones (TAZs. The first sub-model is a Nested Logit Model (NLM that estimates the probability of a driver has or has no multiple routes, and if the driver has multiple routes, the route selection criteria are based on the access point’s intersection control type or other factors. The second sub-model is a Mixed Logit (MXL model. It estimates the probabilities of the type of intersection control preferred by a driver. The third sub-model is a NLM that estimates the probabilities of a driver selecting his/her route for its shortest travel time or to avoid pedestrian, and if the aim is to take the fastest route, the decision criteria is based on the shortest distance or minimum stops and turns. Data gathered in a questionnaire survey were used to estimate the sub-models. The attributes of the utility functions of the sub-models are the driver’s demographic and trip characteristics. The model provides a means for transportation planners to distribute the total number of home-based trips generated within a TAZ to the access points along the major streets that bound the TAZ.

Analysis of inertia thresholds based on real-world route choice data

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Vreeswijk, Jacob Dirk; van Berkum, Eric C.; van Arem, Bart

2014-01-01

In the context of route choice, inertial behaviour shows that drivers make choices that are satisfactory rather than optimal. Consequently, drivers may not necessarily alter their choice when confronted with a travel time increase on the current choice or a travel time decrease of a choice

Converging migration routes of Eurasian hobbies Falco subbuteo crossing the African equatorial rain forest.

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Strandberg, Roine; Klaassen, Raymond H G; Hake, Mikael; Olofsson, Patrik; Alerstam, Thomas

2009-02-22

Autumn migration of adult Eurasian hobbies Falco subbuteo from Europe to southern Africa was recorded by satellite telemetry and observed routes were compared with randomly simulated routes. Two non-random features of observed routes were revealed: (i) shifts to more westerly longitudes than straight paths to destinations and (ii) strong route convergence towards a restricted area close to the equator (1 degree S, 15 degrees E). The birds migrated south or southwest to approximately 10 degrees N, where they changed to south-easterly courses. The maximal spread between routes at 10 degrees N (2134 km) rapidly decreased to a minimum (67 km) close to the equator. We found a striking relationship between the route convergence and the distribution of continuous rainforest, suggesting that hobbies minimize flight distance across the forest, concentrating in a corridor where habitat may be more suitable for travelling and foraging. With rainforest forming a possible ecological barrier, many migrants may cross the equator either at 15 degrees E, similar to the hobbies, or at 30-40 degrees E, east of the rainforest where large-scale migration is well documented. Much remains to be understood about the role of the rainforest for the evolution and future of the trans-equatorial Palaearctic-African bird migration systems.

Generation and quality assessment of route choice sets in public transport networks by means of RP data analysis

DEFF Research Database (Denmark)

Larsen, Marie Karen; Nielsen, Otto Anker; Prato, Carlo Giacomo

2010-01-01

Literature in route choice modelling shows that a lot of attention has been devoted to route choices of car drivers, but much less attention has been dedicated to route choices of public transport users. As modelling route choice behaviour consists of generating relevant routes and estimating...... discrete choice models, this paper focuses on the issue of choice set generation in public transport networks. Specifically, this paper describes the generation of choice sets for users of the Greater Copenhagen public transport system by applying a doubly stochastic path generation algorithm...

An advanced traveler navigation system adapted to route choice preferences of the individual users

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Mahyar Amirgholy

2017-12-01

Full Text Available The majority of existing navigation systems only account for a single aspect of the route choice, like travel time or distance, in finding the optimal route for the trips in the network. In this research, we first identify a range of diverse factors that travelers take into account in their route choice decision in the network. A stated preference survey is conducted to show the heterogeneity in the preferences of users and its dependence to the purpose of the trips over the weekdays and weekends. Interestingly, results of the survey show that road safety is the most influential factor in the route choice decision of the average participants over weekends, exceeding even the travel time, and participants give more importance to the scenic quality of the routes for their weekend trips in comparison to their weekday trips. The results of the second part of the survey also indicate that in 27% of the cases participants choose routes other than the ones suggested by navigation systems, and 33% of the times that they take the suggested routes, they modify these routes according to their own preferences. The partial inability of existing navigation systems to suggest the routes that match the preferences of users can be attributed to ignoring (1 the diversity in influential factors and (2 the heterogeneity in preferences of the users by these systems. We propose a dynamic mixed logit route choice model to include the effects of information and learning to estimate parameters of a multivariable utility function for individual users based on their own historical route choice data over time. Finally, we present the concept of a smart navigation system that can gather the required information from real-time and online sources to suggest the routes that best match the users’ own preferences.

A constrained multinomial Probit route choice model in the metro network: Formulation, estimation and application

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Zhang, Yongsheng; Wei, Heng; Zheng, Kangning

2017-01-01

Considering that metro network expansion brings us with more alternative routes, it is attractive to integrate the impacts of routes set and the interdependency among alternative routes on route choice probability into route choice modeling. Therefore, the formulation, estimation and application of a constrained multinomial probit (CMNP) route choice model in the metro network are carried out in this paper. The utility function is formulated as three components: the compensatory component is a function of influencing factors; the non-compensatory component measures the impacts of routes set on utility; following a multivariate normal distribution, the covariance of error component is structured into three parts, representing the correlation among routes, the transfer variance of route, and the unobserved variance respectively. Considering multidimensional integrals of the multivariate normal probability density function, the CMNP model is rewritten as Hierarchical Bayes formula and M-H sampling algorithm based Monte Carlo Markov Chain approach is constructed to estimate all parameters. Based on Guangzhou Metro data, reliable estimation results are gained. Furthermore, the proposed CMNP model also shows a good forecasting performance for the route choice probabilities calculation and a good application performance for transfer flow volume prediction. PMID:28591188

Blockage of migration routes by dam construction: can migratory fish find alternative routes?

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Rosimeire Ribeiro Antonio

Full Text Available The present study explored the interaction between the upriver migration of fish and the blockage of their migration routes by dam construction. Specifically, we studied (i the capacity of migratory fish to locate alternative routes in the presence of an obstacle, and (ii the behavior of the fish after they were artificially transferred to the reservoir. With the use of the mark-recapture technique (tagging, the study was carried out near Porto Primavera Dam (UHE Engenheiro Sérgio Motta between 1994 and 1999, a period prior to the closure of the floodgates and the installation and operation of the fish pass facilities. The fish were caught in the dam forebay downstream, marked with LEA type tags, and released upstream (5113 individuals; 14 species and downstream (1491; 12 from the dam. The recaptures were carried out by local professional and amateur fishermen. A total of 188 individuals (2.8% were recaptured, mostly the curimba Prochilodus lineatus. Nearly half of the recaptures downstream occurred in tributaries, especially in the Paranapanema River, indicating that in the presence of an obstacle the fish are able to locate alternative migration routes. The remainder stayed in the main channel of the Paraná River, at a mean distance of less than 50 km from the release point. Of the fish released upriver from the dam, approximately half were recaptured downriver. Although the river was only partly dammed, the movement of the fish downriver suggests that they became disoriented after being transferred. Those that remained upriver avoided the reservoir and moved, rather rapidly, toward the lotic stretches farther upstream. From these results it is clear that, in the course of the decision process in installing fish passes, it is necessary to take into account the existence of spawning and nursery areas downriver and upriver from the reservoir.

Many routes leading to Rome: Potential causes for the multi-route migration system of Red Knots Calidris canutus islandica

NARCIS (Netherlands)

Bauer, S.; Ens, B.J.; Klaassen, M.R.J.

2010-01-01

Migrants, such as birds or representatives of other taxa, usually make use of several stopover sites to cover the distance between their site of origin and destination. Potentially, multiple routes exist, but often little is known about the causes and consequences of alternative migration routes.

Glacial refugia and migration routes of the Neotropical genus Trizeuxis (Orchidaceae

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Marta Kolanowska

2013-09-01

Full Text Available The morphology and anatomy of the monotypic genus Trizeuxis make this taxon almost impossible to recognize in fossil material and hereby difficult object of historical geographic studies. To estimate the distribution of potential refugia during the last glacial maximum and migration routes for Trizeuxis the ecological niche modeling was performed. The potential niche modeling was done using maximum entropy method implemented in Maxent application based on the species presence-only observations. As input data climatic variables and the digital elevation model were used. Two models of suitable glacial habitats distribution were prepared – for the studied species and for its host. The compiled map of the suitable habitats distribution of T. falcata and P. guajava during the last glacial maximum (LGM indicate two possible refugia for the studied orchid genus. The first one was located in the Madre de Dios region and the other one in the Mosquito Coast. The models suggest the existence of two migration routes of Trizeuxis species. The results indicate that the ecological niche modeling (ENM is a useful tool for analyzing not only the possible past distribution of the species, but may be also applied to determine the migration routes of the organisms not found in the fossil material.

Teaching migration routes to canada geese and trumpeter swans using ultralight aircraft, 1990-2001

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Sladen, William J. L.; Lishman, W.A.; Ellis, D.H.; Shire, G.G.; Rininger, D.L.; Rees, Eileen C.; Earnst, Susan L.; Coulson, John C.

2002-01-01

This paper summarizes eleven years (1990-2001) of experiments to teach Canada Geese (Branta canadensis) and Trumpeter Swans (Cygnus buccinator) pre-selected migration routes using ultralight aircraft. When Canada Geese were trained to follow an ultralight aircraft for southward autumn migrations of 680 or 1,320 km, 81% (83/103) returned on their own in the next spring to near their place of training. In contrast, none returned of 21 similarly raised geese that were transported south in a closed truck over a route of 680 km. Trumpeter Swans have proven more difficult to train. However, in two experiments in which Trumpeter Swans followed an ultralight for the entire pre-selected route, one of three and two of four returned close to their training area. A stage-by-stage method, in which swans were transported in trucks between stops, flown in the vicinity and penned with a view of the night sky, has shown some promise. So far an established migration route (north and south twice) has been confirmed in only two geese

The Effects of the Emission Cost on Route Choices of International Container Ships

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Hyangsook Lee

2016-01-01

Full Text Available Maritime freight shipping has increased significantly and air pollution from international ships has grown accordingly, having serious environmental effects all over the world. This paper analyzes the effects of the emission cost on ocean route choices, focusing on international container ships. First, the paper formulates a freight network model that captures decisions and interactions of ocean carriers and port terminal operators in the maritime freight transport system. Then, the emission cost is calculated based on an activity-based approach as a component of the ocean transportation cost function. A case study is examined to find if the emission cost affects ocean route choices. The results indicate that the optimal ocean route and transportation cost are changed distinctively due to the emission cost. The research discusses how the emission cost plays a role in route changes and why ocean carriers have to consider these costs in their routing decisions.

Risk Route Choice Analysis and the Equilibrium Model under Anticipated Regret Theory

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pengcheng yuan

2014-02-01

Full Text Available The assumption about travellers’ route choice behaviour has major influence on the traffic flow equilibrium analysis. Previous studies about the travellers’ route choice were mainly based on the expected utility maximization theory. However, with the gradually increasing knowledge about the uncertainty of the transportation system, the researchers have realized that there is much constraint in expected util­ity maximization theory, because expected utility maximiza­tion requires travellers to be ‘absolutely rational’; but in fact, travellers are not truly ‘absolutely rational’. The anticipated regret theory proposes an alternative framework to the tra­ditional risk-taking in route choice behaviour which might be more scientific and reasonable. We have applied the antici­pated regret theory to the analysis of the risk route choosing process, and constructed an anticipated regret utility func­tion. By a simple case which includes two parallel routes, the route choosing results influenced by the risk aversion degree, regret degree and the environment risk degree have been analyzed. Moreover, the user equilibrium model based on the anticipated regret theory has been established. The equivalence and the uniqueness of the model are proved; an efficacious algorithm is also proposed to solve the model. Both the model and the algorithm are demonstrated in a real network. By an experiment, the model results and the real data have been compared. It was found that the model re­sults can be similar to the real data if a proper regret degree parameter is selected. This illustrates that the model can better explain the risk route choosing behaviour. Moreover, it was also found that the traveller’ regret degree increases when the environment becomes more and more risky.

A nested recursive logit model for route choice analysis

DEFF Research Database (Denmark)

Mai, Tien; Frejinger, Emma; Fosgerau, Mogens

2015-01-01

choices and the model does not require any sampling of choice sets. Furthermore, the model can be consistently estimated and efficiently used for prediction.A key challenge lies in the computation of the value functions, i.e. the expected maximum utility from any position in the network to a destination....... The value functions are the solution to a system of non-linear equations. We propose an iterative method with dynamic accuracy that allows to efficiently solve these systems.We report estimation results and a cross-validation study for a real network. The results show that the NRL model yields sensible......We propose a route choice model that relaxes the independence from irrelevant alternatives property of the logit model by allowing scale parameters to be link specific. Similar to the recursive logit (RL) model proposed by Fosgerau et al. (2013), the choice of path is modeled as a sequence of link...

A Day-to-Day Route Choice Model Based on Reinforcement Learning

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Fangfang Wei

2014-01-01

Full Text Available Day-to-day traffic dynamics are generated by individual traveler’s route choice and route adjustment behaviors, which are appropriate to be researched by using agent-based model and learning theory. In this paper, we propose a day-to-day route choice model based on reinforcement learning and multiagent simulation. Travelers’ memory, learning rate, and experience cognition are taken into account. Then the model is verified and analyzed. Results show that the network flow can converge to user equilibrium (UE if travelers can remember all the travel time they have experienced, but which is not necessarily the case under limited memory; learning rate can strengthen the flow fluctuation, but memory leads to the contrary side; moreover, high learning rate results in the cyclical oscillation during the process of flow evolution. Finally, both the scenarios of link capacity degradation and random link capacity are used to illustrate the model’s applications. Analyses and applications of our model demonstrate the model is reasonable and useful for studying the day-to-day traffic dynamics.

Avian migrants adjust migration in response to environmental conditions en route

DEFF Research Database (Denmark)

Tøttrup, Anders P; Thorup, Kasper; Rainio, Kalle

2008-01-01

The onset of migration in birds is assumed to be primarily under endogenous control in long-distance migrants. Recently, climate changes appear to have been driving a rapid change in breeding area arrival. However, little is known about the climatic factors affecting migratory birds during...... covering the entire migration period every year from observatories located in the Middle East and northern Europe, we show that passage of the Sahara Desert is delayed and correlated with improved conditions in the wintering areas. By contrast, migrants travel more rapidly through Europe, and adjust...... the migration cycle, or whether recently reported phenological changes are caused by plastic behavioural responses or evolutionary change. Here, we investigate how environmental conditions in the wintering areas as well as en route towards breeding areas affect timing of migration. Using data from 1984 to 2004...

Variability in Migration Routes Influences Early Marine Survival of Juvenile Salmon Smolts.

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Nathan B Furey

Full Text Available Variability in animal migratory behavior is expected to influence fitness, but few empirical examples demonstrating this relationship exist. The initial marine phase in the migration of juvenile salmon smolts has been identified as a potentially critical life history stage to overall population productivity, yet how fine-scale migration routes may influence survival are unknown. Large-scale acoustic telemetry studies have estimated survival rates of outmigrant Pacific salmon smolts through the Strait of Georgia (SOG along the British Columbian coastline to the Pacific Ocean, but these data have not been used to identify and characterize fine-scale movements. Data collected on over 850 sockeye salmon (Oncorhynchus nerka and steelhead (Oncorhynchus mykiss smolts detected at an array in the Strait of Georgia in 2004-2008 and 2010-2013 were analyzed to characterize migration routes and link movements to subsequent survival at an array 250 km further along the marine migration pathway. Both species exhibited disproportionate use of the most eastern route in the Strait of Georgia (Malaspina Strait. While many smolts moved across the northern Strait of Georgia acoustic array with no indication of long-term milling or large-scale east-to-west movements, large proportions (20-40% of sockeye and 30-50% of steelhead exhibited a different behavior, apparently moving in a westward or counterclockwise pattern. Variability in migratory behavior for both species was linked to subsequent survival through the Strait of Georgia. Survival for both species was influenced by initial east-to-west location, and sockeye were further influenced by migration timing and duration of time spent near the northern Strait of Georgia array. Westward movements result in a net transport of smolts from Malaspina Strait to the Strait of Georgia, particularly for steelhead. Counterclockwise movements may be due to the currents in this area during the time of outmigration, and the

Modelling Stochastic Route Choice Behaviours with a Closed-Form Mixed Logit Model

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Xinjun Lai

2015-01-01

Full Text Available A closed-form mixed Logit approach is proposed to model the stochastic route choice behaviours. It combines both the advantages of Probit and Logit to provide a flexible form in alternatives correlation and a tractable form in expression; besides, the heterogeneity in alternative variance can also be addressed. Paths are compared by pairs where the superiority of the binary Probit can be fully used. The Probit-based aggregation is also used for a nested Logit structure. Case studies on both numerical and empirical examples demonstrate that the new method is valid and practical. This paper thus provides an operational solution to incorporate the normal distribution in route choice with an analytical expression.

Multimodal route choice models of public transport passengers in the Greater Copenhagen Area

DEFF Research Database (Denmark)

Anderson, Marie Karen; Nielsen, Otto Anker; Prato, Carlo Giacomo

2014-01-01

Understanding route choice behavior is crucial to explain travelers’ preferences and to predict traffic flows under different scenarios. A growing body of literature has concentrated on public transport users without, however, concentrating on multimodal public transport networks because......,641 public transport users in the Greater Copenhagen Area.A two-stage approach consisting of choice set generation and route choice model estimation allowed uncovering the preferences of the users of this multimodal large-scale public transport network. The results illustrate the rates of substitution...... not only of the in-vehicle times for different public transport modes, but also of the other time components (e.g., access, walking, waiting, transfer) composing the door-to-door experience of using a multimodal public transport network, differentiating by trip length and purpose, and accounting...

Migration routes and stopover sites of the Eurasian Spoonbill (Platalea leucorodia between the Carpathian Basin and wintering areas

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Pigniczki Csaba

2016-06-01

Full Text Available Understanding the migration routes of the Central European Spoonbill population is important for their conservation. Here we analysed movements of 3186 individuals of Eurasian Spoonbills marked with colour rings in the Carpathian Basin (Hungary, Croatia and Serbia between 2003 and 2015, and a satellite tagged individual, which was equipped in Italy in 2013, and later moved to the Carpathian Basin. Migration routes of these Spoonbills predominantly followed the Adriatic Flyway, however, some birds were also found to both east and west from this flyway. We identified 59 stopover sites, 55 of which were located along the Adriatic Flyway. Colourringed juveniles (1cy, on average, spent 4.0±0.9 (SE days on the stopover sites along the Adriatic Flyway during autumn migration, while non-juveniles (> 1cy spent 2.6±1.0 (SE days during autumn and 2.1±0.4 (SE days during spring migration there. These durations were not significantly different. Duration of stops of the satellite tracked individual was between 7 and 15 days during autumn and between 1 and 12 days during spring migration. Our results indicate the existence of two alternative routes of the Adriatic Flyway between the Carpathian Basin and the wintering areas in southern Italy and the central part of coastal North-Africa. The North-Adriatic Flyway includes stopover sites in north-eastern Italy at the river mouth of River Isonzo, Lagunes of Venice and wetlands around River Po. The South Adriatic Flyway leads through the Balkan Peninsula, with stopover sites at the karst lakes of Bosnia and Herzegovina, mouth of the river Neretva (Croatia, Ulcinj Salinas (Montenegro and wetlands in Gulf of Manfredonia (Italy. This hypothesis was also supported by the migration of the satellite tagged individual, the paths of which was described here in detail. The average coordinates of spring and autumn stopover sites were located at different parts of the flyway: it was in south-western Italy during autumn

A Joint Route Choice Model for Electric and Conventional Car Users

DEFF Research Database (Denmark)

Jensen, Anders Fjendbo; Rasmussen, Thomas Kjær; Prato, Carlo Giacomo

Introduction Worldwide, governments have committed to reducing air pollution and carbon emissions. With a higher share of renewable sources in the electricity production, battery electric cars (EVs) could play a significant role in maintaining these commitments. Growing literature shows...... an increasing interest in EVs and their market, but current EV travel demand studies are usually based on data collected from users of conventional gasoline or diesel engine cars (CVs) (see e.g. (Golob and Gould 1998; Pearre et al. 2011; Greaves et al. 2014). EVs are however different from CVs in a number...... effects, such as effects on the electricity network and the transport network. The objective of this study is to use revealed preferences (RP) data to investigate differences in route choice behaviour between CV and EV users. To our knowledge, this is the first time that a state-of-the-art route choice...

Migration routes and strategies in a highly aerial migrant, the common swift Apus apus, revealed by light-level geolocators.

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Susanne Åkesson

Full Text Available The tracking of small avian migrants has only recently become possible by the use of small light-level geolocators, allowing the reconstruction of whole migration routes, as well as timing and speed of migration and identification of wintering areas. Such information is crucial for evaluating theories about migration strategies and pinpointing critical areas for migrants of potential conservation value. Here we report data about migration in the common swift, a highly aerial and long-distance migrating species for which only limited information based on ringing recoveries about migration routes and wintering areas is available. Six individuals were successfully tracked throughout a complete migration cycle from Sweden to Africa and back. The autumn migration followed a similar route in all individuals, with an initial southward movement through Europe followed by a more southwest-bound course through Western Sahara to Sub-Saharan stopovers, before a south-eastward approach to the final wintering areas in the Congo basin. After approximately six months at wintering sites, which shifted in three of the individuals, spring migration commenced in late April towards a restricted stopover area in West Africa in all but one individual that migrated directly towards north from the wintering area. The first part of spring migration involved a crossing of the Gulf of Guinea in those individuals that visited West Africa. Spring migration was generally wind assisted within Africa, while through Europe variable or head winds were encountered. The average detour at about 50% could be explained by the existence of key feeding sites and wind patterns. The common swift adopts a mixed fly-and-forage strategy, facilitated by its favourable aerodynamic design allowing for efficient use of fuel. This strategy allowed swifts to reach average migration speeds well above 300 km/day in spring, which is higher than possible for similar sized passerines. This study

Elementary students' evacuation route choice in a classroom: A questionnaire-based method

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Chen, Liang; Tang, Tie-Qiao; Huang, Hai-Jun; Song, Ziqi

2018-02-01

Children evacuation is a critical but challenging issue. Unfortunately, existing researches fail to effectively describe children evacuation, which is likely due to the lack of experimental and empirical data. In this paper, a questionnaire-based experiment was conducted with children aged 8-12 years to study children route choice behavior during evacuation from in a classroom with two exits. 173 effective questionnaires were collected and the corresponding data were analyzed. From the statistical results, we obtained the following findings: (1) position, congestion, group behavior, and backtracking behavior have significant effects on children route choice during evacuation; (2) age only affects children backtracking behavior, and (3) no prominent effects based on gender and guidance were observed. The above findings may help engineers design some effective evacuation strategies for children.

A Stochastic Route Choice Model for Car Travellers in the Copenhagen Region

DEFF Research Database (Denmark)

Nielsen, Otto Anker; Frederiksen, Rasmus Dyhr; Daly, A.

2002-01-01

The paper presents a large-scale stochastic road traffic assignment model for the Copenhagen Region. The model considers several classes of passenger cars (different trip purposes), vans and trucks, each with its own utility function on which route choices are based. The utility functions include...

An aggregate method to calibrate the reference point of cumulative prospect theory-based route choice model for urban transit network

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Zhang, Yufeng; Long, Man; Luo, Sida; Bao, Yu; Shen, Hanxia

2015-12-01

Transit route choice model is the key technology of public transit systems planning and management. Traditional route choice models are mostly based on expected utility theory which has an evident shortcoming that it cannot accurately portray travelers' subjective route choice behavior for their risk preferences are not taken into consideration. Cumulative prospect theory (CPT), a brand new theory, can be used to describe travelers' decision-making process under the condition of uncertainty of transit supply and risk preferences of multi-type travelers. The method to calibrate the reference point, a key parameter to CPT-based transit route choice model, determines the precision of the model to a great extent. In this paper, a new method is put forward to obtain the value of reference point which combines theoretical calculation and field investigation results. Comparing the proposed method with traditional method, it shows that the new method can promote the quality of CPT-based model by improving the accuracy in simulating travelers' route choice behaviors based on transit trip investigation from Nanjing City, China. The proposed method is of great significance to logical transit planning and management, and to some extent makes up the defect that obtaining the reference point is solely based on qualitative analysis.

DATA-ORIENTED ALGORITHM FOR ROUTE CHOICE SET GENERATION IN A METROPOLITAN AREA WITH MOBILE PHONE GPS DATA

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T. Nakamura

2012-07-01

Full Text Available Nowadays, for the estimation of traffic demand or people flow, modelling route choice activity in road networks is an important task and many algorithms have been developed to generate route choice sets. However, developing an algorithm based on a small amount of data that can be applied generally within a metropolitan area is difficult. This is because the characteristics of road networks vary widely. On the other hand, recently, the collection of people movement data has lately become much easier, especially through mobile phones. Lately, most mobile phones include GPS functionality. Given this background, we propose a data-oriented algorithm to generate route choice sets using mobile phone GPS data. GPS data contain a number of measurement errors; hence, they must be adjusted to account for these errors before use in advanced people movement analysis. However, this is time-consuming and expensive, because an enormous amount of daily data can be obtained. Hence, the objective of this study is to develop an algorithm that can easily manage GPS data. Specifically, at first movement data from all GPS data are selected by calculating the speed. Next, the nearest roads in the road network are selected from the GPS location and count such data for each road. Then An algorithm based on the GSP (Gateway Shortest Path algorithm is proposed, which searches the shortest path through a given gateway. In the proposed algorithm, the road for which the utilization volume calculated by GPS data is large is selected as the gateway. Thus, route choice sets that are based on trends in real GPS data are generated. To evaluate the proposed method, GPS data from 0.7 million people a year in Japan and DRM (Digital Road Map as the road network are used. DRM is one of the most detailed road networks in Japan. Route choice sets using the proposed algorithm are generated and the cover rate of the utilization volume of each road under evaluation is calculated. As a

Insight into the Migration Routes of Plutella xylostella in China Using mtCOI and ISSR Markers

Science.gov (United States)

Tian, Lixia; Xu, Baoyun; Xie, Wen; Wang, Shaoli; Zhang, Youjun; Wang, Xiangjing; Wu, Qingjun

2015-01-01

The larvae of the diamondback moth, Plutella xylostella, cause major economic losses to cruciferous crops, including cabbage, which is an important vegetable crop in China. In this study, we used the mitochondrial COI gene and 11 ISSR markers to characterize the genetic structure and seasonal migration routes of 23 P. xylostella populations in China. Both the mitochondrial and nuclear markers revealed high haplotype diversity and gene flow among the populations, although some degree of genetic isolation was evident between the populations of Hainan Island and other sampling sites. The dominant haplotypes, LX1 and LX2, differed significantly from all other haplotypes both in terms of the number of individuals with those haplotypes and their distributions. Haplotypes that were shared among populations revealed that P. xylostella migrates from the lower reaches of the Yangtze River to northern China and then to northeastern China. Our results also revealed another potential migration route for P. xylostella, i.e., from southwestern China to both northwestern and southern China. PMID:26098353

Youth Migration in Indonesia: Decision to Move and Choice of Destination Areas

Directory of Open Access Journals (Sweden)

Meirina Ayumi Malamassam

2016-08-01

Full Text Available Using intercensal population survey data, this paper examines migration behavior of youth in Indonesia aged 15 to 24 years old. Logistic regressions are employed to understand factors influencing youth’s decision to migrate as well as their choice of destination areas. The study findings suggest that migration preferences are determined by both the individual characteristics as well as the development level in both areas of origin and destination. It is also shown that education plays an important role in youth migration in Indonesia, not only in improving individual’s capacity to migrate, but also in prompting migration to big cities. In addition, youth migrants tend to move to areas with similar characteristics or similar cultural background to their areas of origin. For most of young people, migration is considered as an attempt for gaining upward social mobility, thus the prevalence of youth migration to less developed areas is low.

Route Choice in Subway Station during Morning Peak Hours: A Case of Guangzhou Subway

Directory of Open Access Journals (Sweden)

Jie Xu

2015-01-01

Full Text Available This paper is aimed at crowding phenomenon in the subway. As passengers are inclined to choose the route with minimum disutility, we put forward a route choice model which is constructed to achieve minimum objective function of feasibility for the optimal solution. Meanwhile we set passenger volume threshold values according to capacity of facilities. In the case of actual capacity exceeding the threshold, the decision node of constrained route will be selected; computing procedure about searching decision points will be presented. Then we should set rational restrictions at the decision node of the minimum utility function route to prevent too many passengers’ access to platform. Through certification, this series of methods can effectively ensure the safety of the station efficient operation.

Dynamic Route Choice Modelling of the Effects of Travel Information using RP Data

NARCIS (Netherlands)

De Moraes Ramos, G.

2015-01-01

Traffic congestion is experienced by a great number of travellers during peak hours and is directly influenced by travel-related decisions, such as route choice decisions. In order to minimize problems that arise from congestion, such as delays, uncertainty and environmental effects, there has been

Insight into the Migration Routes of Plutella xylostella in China Using mtCOI and ISSR Markers.

Directory of Open Access Journals (Sweden)

Jiaqiang Yang

Full Text Available The larvae of the diamondback moth, Plutella xylostella, cause major economic losses to cruciferous crops, including cabbage, which is an important vegetable crop in China. In this study, we used the mitochondrial COI gene and 11 ISSR markers to characterize the genetic structure and seasonal migration routes of 23 P. xylostella populations in China. Both the mitochondrial and nuclear markers revealed high haplotype diversity and gene flow among the populations, although some degree of genetic isolation was evident between the populations of Hainan Island and other sampling sites. The dominant haplotypes, LX1 and LX2, differed significantly from all other haplotypes both in terms of the number of individuals with those haplotypes and their distributions. Haplotypes that were shared among populations revealed that P. xylostella migrates from the lower reaches of the Yangtze River to northern China and then to northeastern China. Our results also revealed another potential migration route for P. xylostella, i.e., from southwestern China to both northwestern and southern China.

Long-term changes in migration timing of Song Thrush Turdus philomelos at the southern Baltic coast in response to temperatures on route and at breeding grounds.

Science.gov (United States)

Redlisiak, Michał; Remisiewicz, Magdalena; Nowakowski, Jarosław K

2018-05-26

Climate warming causes the advancement of spring arrival of many migrant birds breeding in Europe, but the effects on their autumn migration are less known. We aimed to determine any changes in the timing of Song Thrush captured during spring and autumn migrations at the Polish Baltic coast from 1975 to 2014, and if these were related to long-term changes of temperature at their breeding grounds and migration routes. The timing of spring migration at Hel ringing station in 1975-2014 did not show long-term advance, but they had responded to environmental conditions on the year-to-year basis. The warmer the temperatures were in April on their migration route, the earlier were the dates of the median and the end of spring migration at Hel. The beginning of autumn migration at the Mierzeja Wiślana ringing station advanced by 5 days between 1975 and 2014. The warmer the April on route, and the July at the Song Thrushes' breeding grounds, the earlier young birds began autumn migration across the Baltic coast. We suggest this was a combined effect of adults' migration and breeding early during warm springs and young birds getting ready faster for autumn migration during warm summers. The average time span of 90% of the autumn migration was extended by 5 days, probably because of early migration of young birds from first broods and late of those from second broods enabled by warm springs and summers. The response of Song Thrushes' migration timing to temperatures on route and at the breeding grounds indicated high plasticity in the species and suggested it might adapt well to climate changes.

Buffer Management and Hybrid Probability Choice Routing for Packet Delivery in Opportunistic Networks

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Daru Pan

2012-01-01

Full Text Available Due to the features of long connection delays, frequent network partitions, and topology unsteadiness, the design of opportunistic networks faces the challenge of how to effectively deliver data based only on occasional encountering of nodes, where the conventional routing schemes do not work properly. This paper proposes a hybrid probability choice routing protocol with buffer management for opportunistic networks. A delivery probability function is set up based on continuous encounter duration time, which is used for selecting a better node to relay packets. By combining the buffer management utility and the delivery probability, a total utility is used to decide whether the packet should be kept in the buffer or be directly transmitted to the encountering node. Simulation results show that the proposed routing outperforms the existing one in terms of the delivery rate and the average delay.

Migration routes and staging areas of trans-Saharan Turtle Doves appraised from light-level geolocators.

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Cyril Eraud

Full Text Available The identification of migration routes, wintering grounds and stopover sites are crucial issues for the understanding of the Palearctic-African bird migration system as well as for the development of relevant conservation strategies for trans-Saharan migrants. Using miniaturized light-level geolocators we report a comprehensive and detailed year round track of a granivorous trans-Saharan migrant, the European Turtle Dove (Streptopelia turtur. From five recovered loggers, our data provide new insights on migratory journeys and winter destinations of Turtle Doves originating from a breeding population in Western France. Data confirm that Turtle Doves wintered in West Africa. The main wintering area encompassed Western Mali, the Inner Delta Niger and the Malian/Mauritanian border. Some individuals also extended their wintering ranges over North Guinea, North-West of Burkina Faso and the Ivory-Coast. Our results reveal that all individuals did not spend the winter period at a single location; some of them experienced a clear eastward shift of several hundred kilometres. We also found evidence for a loop migration pattern, with a post-breeding migration flyway lying west of the spring route. Finally, we found that on their way back to breeding grounds Turtle Doves needed to refuel after crossing the Sahara desert. Contrary to previous suggestions, our data reveal that birds used stopover sites for several weeks, presumably in Morocco and North Algeria. This later finding is a crucial issue for future conservation strategies because environmental conditions on these staging areas might play a pivotal role in population dynamics of this declining species.

Route optimisation and solving Zermelo’s navigation problem during long distance migration in cross flows

DEFF Research Database (Denmark)

Hays, Graeme C.; Christensen, Asbjørn; Fossette, Sabrina

2014-01-01

The optimum path to follow when subjected to cross flows was first considered over 80 years ago by the German mathematician Ernst Zermelo, in the context of a boat being displaced by ocean currents, and has become known as the ‘Zermelo navigation problem’. However, the ability of migrating animals...... to solve this problem has received limited consideration, even though wind and ocean currents cause the lateral displacement of flyers and swimmers, respectively, particularly during long-distance journeys of 1000s of kilometres. Here, we examine this problem by combining long-distance, open-ocean marine...... not follow the optimum (Zermelo's) route. Even though adult marine turtles regularly complete incredible long-distance migrations, these vertebrates primarily rely on course corrections when entering neritic waters during the final stages of migration. Our work introduces a new perspective in the analysis...

Route-external and route-internal landmarks in route descriptions : Effects of route length and map design

NARCIS (Netherlands)

Westerbeek, Hans; Maes, Alfons

2013-01-01

Landmarks are basic ingredients in route descriptions. They often mark choice points: locations where travellers choose from different options how to continue the route. This study focuses on one of the loose ends in the taxonomy of landmarks. In a memory-based production experiment in which

Fall migration routes, timing, and wintering sites of North American ospreys as determined by satellite telemetry

Science.gov (United States)

Martell, M.S.; Henny, Charles J.; Nye, P.; Solensky, Matthew J.

2001-01-01

Satellite telemetry was used to determine fall migratory movements of Ospreys (Pandion haliaetus) breeding in the United States. Study areas were established along the lower Columbia River between Oregon and Washington; in north-central Minnesota; on Shelter Island, New York; and in southern New Jersey. Seventy-four adults (25 males, 49 females) were tracked from 1995 through 1999. Migration routes differed among populations but not by sex. Western Ospreys migrated through California and to a lesser degree other western states and wintered in Mexico (88%), El Salvador (6%), and Honduras (6%) (25.9A?N to 13.0A?N and 108.3A?W to 87.3A?W). Minnesota Ospreys migrated along three routes: (1) through the Central U.S. and then along the east coast of Mexico, (2) along the Mississippi River Valley, then across the Gulf of Mexico, or (3) through the southeastern U.S., then across the Caribbean. East Coast birds migrated along the eastern seaboard of the U.S., through Florida, and across the Caribbean. Midwestern birds wintered from Mexico south to Bolivia (22.35A?N to 13.64A?S, and 91.75A?W to 61.76A?W), while East Coast birds wintered from Florida to as far south as Brazil (27.48A?N to 18.5A?S and 80.4A?W to 57.29A?W). Dates of departure from breeding areas differed significantly between sexes and geographic regions, with females leaving earlier than males. Western birds traveled a shorter distance than either midwestern or eastern Ospreys. Females traveled farther than males from the same population, which resulted in females typically wintering south of males.

Understanding individual routing behaviour.

Science.gov (United States)

Lima, Antonio; Stanojevic, Rade; Papagiannaki, Dina; Rodriguez, Pablo; González, Marta C

2016-03-01

Knowing how individuals move between places is fundamental to advance our understanding of human mobility (González et al. 2008 Nature 453, 779-782. (doi:10.1038/nature06958)), improve our urban infrastructure (Prato 2009 J. Choice Model. 2, 65-100. (doi:10.1016/S1755-5345(13)70005-8)) and drive the development of transportation systems. Current route-choice models that are used in transportation planning are based on the widely accepted assumption that people follow the minimum cost path (Wardrop 1952 Proc. Inst. Civ. Eng. 1, 325-362. (doi:10.1680/ipeds.1952.11362)), despite little empirical support. Fine-grained location traces collected by smart devices give us today an unprecedented opportunity to learn how citizens organize their travel plans into a set of routes, and how similar behaviour patterns emerge among distinct individual choices. Here we study 92 419 anonymized GPS trajectories describing the movement of personal cars over an 18-month period. We group user trips by origin-destination and we find that most drivers use a small number of routes for their routine journeys, and tend to have a preferred route for frequent trips. In contrast to the cost minimization assumption, we also find that a significant fraction of drivers' routes are not optimal. We present a spatial probability distribution that bounds the route selection space within an ellipse, having the origin and the destination as focal points, characterized by high eccentricity independent of the scale. While individual routing choices are not captured by path optimization, their spatial bounds are similar, even for trips performed by distinct individuals and at various scales. These basic discoveries can inform realistic route-choice models that are not based on optimization, having an impact on several applications, such as infrastructure planning, routing recommendation systems and new mobility solutions. © 2016 The Author(s).

Route Fidelity during Marine Megafauna Migration

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Travis W. Horton

2017-12-01

Full Text Available The conservation and protection of marine megafauna require robust knowledge of where and when animals are located. Yet, our ability to predict animal distributions in space and time remains limited due to difficulties associated with studying elusive animals with large home ranges. The widespread deployment of satellite telemetry technology creates unprecedented opportunities to remotely monitor animal movements and to analyse the spatial and temporal trajectories of these movements from a variety of geophysical perspectives. Reproducible patterns in movement trajectories can help elucidate the potential mechanisms by which marine megafauna navigate across vast expanses of open-ocean. Here, we present an empirical analysis of humpback whale (Megaptera novaeangliae, great white shark (Carcharodon carcharias, and northern elephant seal (Mirounga angustirostris satellite telemetry-derived route fidelity movements in magnetic and gravitational coordinates. Our analyses demonstrate that: (1 humpback whales, great white sharks and northern elephant seals are capable of performing route fidelity movements across millions of square kilometers of open ocean with a spatial accuracy of better than 150 km despite temporal separations as long as 7 years between individual movements; (2 route fidelity movements include significant (p < 0.05 periodicities that are comparable in duration to the lunar cycles and semi-cycles; (3 latitude and bedrock-dependent gravitational cues are stronger predictors of route fidelity movements than spherical magnetic coordinate cues when analyzed with respect to the temporally dependent moon illumination cycle. We further show that both route fidelity and non-route fidelity movement trajectories, for all three species, describe overlapping in-phase or antiphase sinusoids when individual movements are normalized to the gravitational acceleration present at migratory departure sites. Although these empirical results provide an

Wind effects on the migration routes of trans-Saharan soaring raptors: geographical, seasonal, and interspecific variation

Science.gov (United States)

Vidal-Mateo, Javier; Mellone, Ugo; López-López, Pascual; La Puente, Javier De; García-Ripollés, Clara; Bermejo, Ana; Urios, Vicente

2016-01-01

Abstract Wind is among the most important environmental factors shaping birds’ migration patterns. Birds must deal with the displacement caused by crosswinds and their behavior can vary according to different factors such as flight mode, migratory season, experience, and distance to goal areas. Here we analyze the relationship between wind and migratory movements of three raptor species which migrate by soaring–gliding flight: Egyptian vulture Neophron percnopterus, booted eagle Aquila pennata, and short-toed snake eagle Circaetus gallicus. We analyzed daily migratory segments (i.e., the path joining consecutive roosting locations) using data recorded by GPS satellite telemetry. Daily movements of Egyptian vultures and booted eagles were significantly affected by tailwinds during both autumn and spring migrations. In contrast, daily movements of short-toed eagles were only significantly affected by tailwinds during autumn migration. The effect of crosswinds was significant in all cases. Interestingly, Egyptian vultures and booted eagles showed latitudinal differences in their behavior: both species compensated more frequently at the onset of autumn migration and, at the end of the season when reaching their wintering areas, the proportion of drift segments was higher. In contrast, there was a higher drift at the onset of spring migration and a higher compensation at the end. Our results highlight the effect of wind patterns on the migratory routes of soaring raptors, with different outcomes in relation to species, season, and latitude, ultimately shaping the loop migration patterns that current tracking techniques are showing to be widespread in many long distance migrants. PMID:29491895

A user equilibrium, traffic assignment model of network route and parking lot choice, with search circuits and cruising flows

OpenAIRE

LEURENT, Fabien; BOUJNAH, Houda

2014-01-01

The paper provides a novel network model of parking and route choice. Parking supply is represented by parking type, management strategy including the fare, capacity and occupancy rate of parking lot, and network location, in relation to access routes along the roadway network. Trip demand is segmented according to origin-destination pair, the disposal of private parking facilities and the individual preferences for parking quality of service. Each traveller is assumed to make a two stage cho...

Distinctive and selective route of PI3K/PKCα-PKCδ/RhoA-Rac1 signaling in osteoclastic cell migration.

Science.gov (United States)

Kim, Jin-Man; Kim, Mi Yeong; Lee, Kyunghee; Jeong, Daewon

2016-12-05

Cell migration during specialized stages of osteoclast precursors, mononuclear preosteoclasts, and multinucleated mature osteoclasts remain uncertain. M-CSF- and osteopontin-induced osteoclastic cell migration was inhibited by function-blocking monoclonal antibodies specific to the integrin αv and β3 subunits, suggesting that integrin αvβ3 mediates migratory signaling induced by M-CSF and osteopontin. M-CSF and osteopontin stimulation was shown to regulate two branched signaling processes, PI3K/PKCα/RhoA axis and PI3K/PKCδ/Rac1 axis. Interestingly, inactivation of RhoA or Rac1 blocked preosteoclast and mature osteoclast migration but not osteoclast precursor migration in a transwell-based cell migration assay. Moreover, the inhibitory effect on preosteoclast and mature osteoclast migration induced by Rac1 inactivation was more effective than that by RhoA inactivation. Collectively, our findings suggest that osteoclast precursor migration depends on PI3K/PKCα-PKCδ signaling mediated via integrin αvβ3 bypassing RhoA and Rac1, whereas preosteoclast and mature osteoclast migration relies on PI3K/PKCα-PKCδ/RhoA-Rac1 axis signaling mediated via integrin αvβ3 with increased dependency on PKCδ/Rac1 signaling route as differentiation progresses. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Integrating meteorology into research on migration

NARCIS (Netherlands)

Shamoun-Baranes, J.; Bouten, W.; van Loon, E.E.

2010-01-01

Atmospheric dynamics strongly influence the migration of flying organisms. They affect, among others, the onset, duration and cost of migration, migratory routes, stop-over decisions, and flight speeds en-route. Animals move through a heterogeneous environment and have to react to atmospheric

A Two-Phase Heuristic Algorithm for the Common Frequency Routing Problem with Vehicle Type Choice in the Milk Run

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Yu Lin

2015-01-01

Full Text Available High frequency and small lot size are characteristics of milk runs and are often used to implement the just-in-time (JIT strategy in logistical systems. The common frequency problem, which simultaneously involves planning of the route and frequency, has been extensively researched in milk run systems. In addition, vehicle type choice in the milk run system also has a significant influence on the operating cost. Therefore, in this paper, we simultaneously consider vehicle routing planning, frequency planning, and vehicle type choice in order to optimize the sum of the cost of transportation, inventory, and dispatch. To this end, we develop a mathematical model to describe the common frequency problem with vehicle type choice. Since the problem is NP hard, we develop a two-phase heuristic algorithm to solve the model. More specifically, an initial satisfactory solution is first generated through a greedy heuristic algorithm to maximize the ratio of the superior arc frequency to the inferior arc frequency. Following this, a tabu search (TS with limited search scope is used to improve the initial satisfactory solution. Numerical examples with different sizes establish the efficacy of our model and our proposed algorithm.

Return Migration and Working Choices

OpenAIRE

TANI, Massimiliano; MAHUTEAU, Stéphane

2008-01-01

Collective Action to Support the Reintegration of Return Migrants in their Country of Origin (MIREM) This paper uses the recent survey carried out in the framework of the MIREM project on returnees to Algeria, Morocco and Tunisia and studies the duration of emigration and the labour force status upon returning. The results suggest that age and the year of emigration play a central role in the migration decision, but they do not support the hypothesis that the duration of migration is deter...

Diversity in destinations, routes and timing of small adult and sub-adult striped bass Morone saxatilis on their southward autumn migration

Science.gov (United States)

Mather, Martha E.; Finn, John T.; Pautzke, Sarah M.; Fox, Dewayne A.; Savoy, Tom; Brundage, Harold M.; Deegan, Linda A.; Muth, Robert M.

2010-01-01

Almost three-quarters of the 46 young adult and sub-adult striped bass Morone saxatilis that were acoustically tagged in Plum Island Estuary, Massachusetts, U.S.A., in the summer of 2006 were detected in one or more southern coastal arrays during their autumn migration. On the basis of the trajectories along which these M. saxatilis moved from feeding to overwintering areas, three migratory groups emerged. After leaving Plum Island Estuary, about half of the fish were detected only in a mid-latitude array, Long Island Sound. The other half of the tagged fish were detected during autumn and winter in a more southern array, the Delaware Estuary. This latter group of fish may have used two routes. Some travelled to the Delaware Estuary through Long Island Sound while other fish may have taken a second, more direct, coastal route that did not include Long Island Sound. Consequently, a seemingly homogeneous group of fish tagged at the same time in the same non-natal feeding location exhibited a diversity of southward movement patterns that could affect population-level processes. These three groups that differed in overwintering location and migration route could be movement contingents with migratory connectivity.

Use of electrical tomography methods to determinate the extension and main migration routes of uncontrolled landfill leachates in fractured areas

Energy Technology Data Exchange (ETDEWEB)

Casado, Ismael, E-mail: iscaferr@gmail.com [Department of Petrology, Geochemistry and Geological Prospectio, Universitat de Barcelona, Martí i Franquès s/n, 08030 Barcelona (Spain); Department of Geology and Environmental Earth Science, Miami University, 501 East High Street, 45056 Oxford, OH (United States); Mahjoub, Himi [Department of Petrology, Geochemistry and Geological Prospectio, Universitat de Barcelona, Martí i Franquès s/n, 08030 Barcelona (Spain); Ecole Nationale des Sciences Appliquées d' Al Hoceima (ENSAH), University Mohammed Premier, Ajdir, Al Hoceima (Morocco); Lovera, Raul [Department of Petrology, Geochemistry and Geological Prospectio, Universitat de Barcelona, Martí i Franquès s/n, 08030 Barcelona (Spain); Fernández, Jesús, E-mail: jfernandezc@aragon.es [Department of Agriculture, Ranching and Environment, Diputación General de Aragon (DGA), Plaza de San Pedro Nolasco, 7, 50071 Zaragoza (Spain); Casas, Albert [Department of Petrology, Geochemistry and Geological Prospectio, Universitat de Barcelona, Martí i Franquès s/n, 08030 Barcelona (Spain)

2015-02-15

This study focuses on the uses of the electrical tomography and its relationship with hydrochemical data in order to characterize contaminated groundwater flows in fractured aquifers. The studied area is contaminated with different hazardous substances like lyndanes, organochlorinated compounds and benzenes coming from the old non-controlled Sardas landfill. The enormous volumes of wastes filling the landfill have generated a convoluted mixture of leachates. Due to the lack of a landfill liner, the leachates have migrated through the fractured Eocene marls towards the Gallego River. The striking correlation between high concentrations of polluted groundwater and low electrical resistivity of the subsurface (< 8 Ω·m) allows defining the principal contaminant migration route thanks to the distribution of these conductive anomalies. This mapping verifies that there is intense tectonical–structural control of the leachate migration, because the deep migration presents the same direction as the geological axis fold. - Highlights: • The outcrop topographic reconstruction is done using cores and aerial photographs. • Hydrochemical and geophysical data allow defining two leachate migration paths. • Conductive anomalies in ERT are linked to high contaminant concentration. • The distribution of conductive anomalies defines the fractured basement migration. • The plume direction reflects important tectonic control in the migration process.

An Institutional Approach to Bordering in Islands: The Canary Islands on the African-European Migration Routes

Directory of Open Access Journals (Sweden)

Dirk Godenau

2012-05-01

Full Text Available Islands play a significant role in international irregular maritime migration. Frequently they are part of maritime interstitial spaces between states, and their location, combined with institutional membership, makes them part of international migration routes and subject to border management strategies. In this paper borders are analysed as social institutions used for regulating relative permeability through rules of entry and exit for persons, goods and capital. Borders institutionalize territoriality and are politically implemented by states. They are selective, also in migration, and irregular border transit is not always indicative of an inability to control. The Canary Islands are used as an illustrative example of how border management at the southern edge of the European Union has evolved towards more coercive deterrence and tighter surveillance. The Canary Islands experienced irregular maritime immigration from the west African coasts during the first decade of the 21st century and most of these migrants intended to use the islands as transit space towards the European continent. Increasing surveillance in countries of origin, enforcement of border controls and stricter return policies were used to stop flows. The so-called “cayuco crisis” in 2006 induced institutional change in border management and forced the active involvement of the EU through FRONTEX.

Dispersal and migration

Directory of Open Access Journals (Sweden)

Schwarz, C.

2004-06-01

philopatric movement of geese using a classic multi–state design. Previous studies of philopaty often rely upon simple return rates —however, good mark–recapture studies do not need to assume equal detection probabilities in space and time. This is likely the most important contribution of multi–state modelling to the study of movement. As with many of these studies, the most pressing problem in the analysis is the explosion in the number of parameters and the need to choose parsimonious modelss to get good precision. Drake and Alisauska demonstrate that model choice still remains an art with a great deal of biological insight being very helpful in the task. There is still plenty of scope for novel methods to study migration. Traditionally, there has been a clear cut distinction between birds being labelled as “migrant” or “resident” on the basis of field observations and qualitative interpretations of patterns of ring–recoveries. However, there are intermediate species where only part of the population migrates (partial migrants or where different components of the population migrate to different extents (differential migrants. Siriwardena, Wernham and Baillie (Siriwardena et al., 2004 develop a novel method that produces a quantitative index of migratory tendency. The method uses distributions of ringing–to–recovery distances to classify individual species’ patterns of movement relative to those of other species. The areas between species’ cumulative distance distributions are used with multi–dimensional scaling to produce a similarity map among species. This map can be used to investigate the factors that affect the migratory strategies that species adopt, such as body size, territoriality and distribution, and in studies of their consequences for demographic parameters such as annual survival and the timing of breeding. The key assumption of the method is the similar recovery effort of species over space and time. It would be interesting to

WLCI researchers employ new approaches to help managers conserve deer migrations

Science.gov (United States)

Allen, Leslie A.; Kauffman, Matthew J.

2012-01-01

Elk, mule deer, pronghorn antelope, moose, and bighorn sheep are iconic animals of the American West. These hooved animals, known as ungulates, commonly travel 30–60 miles between seasonal ranges. These migrations between winter and summer ranges are vital for survival and reproduction. As habitat fragmentation continues, the conservation of ungulate migration routes has received considerable attention in the West and across the globe. For example, it is estimated that many ungulate migration routes in the Greater Yellowstone Ecosystem have already been lost. The traditional migration routes of Wyoming ungulates are threatened by unprecedented levels of energy development and by increasing levels of rural ranchette development (including fences, structures, and roads). In the past, migration corridors have been mapped based primarily on the expert opinions of state game managers, but long-term conservation of Wyoming's ungulate migration routes requires a better understanding of migration ecology and more sophisticated management tools. Wyoming Landscape Conservation Initiative (WLCI) researchers investigated the migration of a large mule deer herd across the Dad and Wild Horse winter ranges in southwest Wyoming, where 2,000 gas wells and 1,609 kilometers of pipelines and roads have been proposed for development.

New Insights on Water Buffalo Genomic Diversity and Post-Domestication Migration Routes From Medium Density SNP Chip Data

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Licia Colli

2018-03-01

Full Text Available The domestic water buffalo is native to the Asian continent but through historical migrations and recent importations, nowadays has a worldwide distribution. The two types of water buffalo, i.e., river and swamp, display distinct morphological and behavioral traits, different karyotypes and also have different purposes and geographical distributions. River buffaloes from Pakistan, Iran, Turkey, Egypt, Romania, Bulgaria, Italy, Mozambique, Brazil and Colombia, and swamp buffaloes from China, Thailand, Philippines, Indonesia and Brazil were genotyped with a species-specific medium-density 90K SNP panel. We estimated the levels of molecular diversity and described population structure, which revealed historical relationships between populations and migration events. Three distinct gene pools were identified in pure river as well as in pure swamp buffalo populations. Genomic admixture was seen in the Philippines and in Brazil, resulting from importations of animals for breed improvement. Our results were largely consistent with previous archeological, historical and molecular-based evidence for two independent domestication events for river- and swamp-type buffaloes, which occurred in the Indo-Pakistani region and close to the China/Indochina border, respectively. Based on a geographical analysis of the distribution of diversity, our evidence also indicated that the water buffalo spread out of the domestication centers followed two major divergent migration directions: river buffaloes migrated west from the Indian sub-continent while swamp buffaloes migrated from northern Indochina via an east-south-eastern route. These data suggest that the current distribution of water buffalo diversity has been shaped by the combined effects of multiple migration events occurred at different stages of the post-domestication history of the species.

Inferring the rules of social interaction in migrating caribou.

Science.gov (United States)

Torney, Colin J; Lamont, Myles; Debell, Leon; Angohiatok, Ryan J; Leclerc, Lisa-Marie; Berdahl, Andrew M

2018-05-19

Social interactions are a significant factor that influence the decision-making of species ranging from humans to bacteria. In the context of animal migration, social interactions may lead to improved decision-making, greater ability to respond to environmental cues, and the cultural transmission of optimal routes. Despite their significance, the precise nature of social interactions in migrating species remains largely unknown. Here we deploy unmanned aerial systems to collect aerial footage of caribou as they undertake their migration from Victoria Island to mainland Canada. Through a Bayesian analysis of trajectories we reveal the fine-scale interaction rules of migrating caribou and show they are attracted to one another and copy directional choices of neighbours, but do not interact through clearly defined metric or topological interaction ranges. By explicitly considering the role of social information on movement decisions we construct a map of near neighbour influence that quantifies the nature of information flow in these herds. These results will inform more realistic, mechanism-based models of migration in caribou and other social ungulates, leading to better predictions of spatial use patterns and responses to changing environmental conditions. Moreover, we anticipate that the protocol we developed here will be broadly applicable to study social behaviour in a wide range of migratory and non-migratory taxa.This article is part of the theme issue 'Collective movement ecology'. © 2018 The Authors.

Biodistribution of radiolabelled human dendritic cells injected by various routes

International Nuclear Information System (INIS)

Quillien, Veronique; Moisan, Annick; Carsin, Andre; Lesimple, Thierry; Lefeuvre, Claudia; Bertho, Nicolas; Devillers, Anne; Toujas, Louis; Adamski, Henri; Leberre, Claudine

2005-01-01

The purpose of this study was to investigate the biodistribution of mature dendritic cells (DCs) injected by various routes, during a cell therapy protocol. In the context of a vaccine therapy protocol for melanoma, DCs matured with Ribomunyl and interferon-gamma were labelled with 111 In-oxine and injected into eight patients along various routes: afferent lymphatic vessel (IL) (4 times), lymph node (IN) (5 times) and intradermally (ID) (6 times). Scintigraphic investigations showed that the IL route allowed localisation of 80% of injected radioactivity in eight to ten nodes. In three cases of IN injection, the entire radioactivity stagnated in the injected nodes, while in two cases, migration to adjacent nodes was observed. This migration was detected rapidly after injection, as with IL injections, suggesting that passive transport occurred along the physiological lymphatic pathways. In two of the six ID injections, 1-2% of injected radioactivity reached a proximal lymph node. Migration was detectable in the first hour, but increased considerably after 24 h, suggesting an active migration mechanism. In both of the aforementioned cases, DCs were strongly CCR7-positive, but this feature was not a sufficient condition for effective migration. In comparison with DCs matured with TNF-α, IL-1β, IL-6 and PGE2, our DCs showed a weaker in vitro migratory response to CCL21, despite comparable CCR7 expression, and higher allostimulatory and TH1 polarisation capacities. The IL route allowed reproducible administration of specified numbers of DCs. The IN route sometimes yielded fairly similar results, but not reproducibly. Lastly, we showed that DCs matured without PGE2 that have in vitro TH1 polarisation capacities can migrate to lymph nodes after ID injection. (orig.)

Integrating meteorology into research on migration.

Science.gov (United States)

Shamoun-Baranes, Judy; Bouten, Willem; van Loon, E Emiel

2010-09-01

Atmospheric dynamics strongly influence the migration of flying organisms. They affect, among others, the onset, duration and cost of migration, migratory routes, stop-over decisions, and flight speeds en-route. Animals move through a heterogeneous environment and have to react to atmospheric dynamics at different spatial and temporal scales. Integrating meteorology into research on migration is not only challenging but it is also important, especially when trying to understand the variability of the various aspects of migratory behavior observed in nature. In this article, we give an overview of some different modeling approaches and we show how these have been incorporated into migration research. We provide a more detailed description of the development and application of two dynamic, individual-based models, one for waders and one for soaring migrants, as examples of how and why to integrate meteorology into research on migration. We use these models to help understand underlying mechanisms of individual response to atmospheric conditions en-route and to explain emergent patterns. This type of models can be used to study the impact of variability in atmospheric dynamics on migration along a migratory trajectory, between seasons and between years. We conclude by providing some basic guidelines to help researchers towards finding the right modeling approach and the meteorological data needed to integrate meteorology into their own research. © The Author 2010. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved.

Effects of competing environmental variables and signage on route-choices in simulated everyday and emergency wayfinding situations.

Science.gov (United States)

Vilar, Elisângela; Rebelo, Francisco; Noriega, Paulo; Duarte, Emília; Mayhorn, Christopher B

2014-01-01

This study examined the relative influence of environmental variables (corridor width and brightness) and signage (directional and exit signs), when presented in competition, on participants' route-choices in two situational variables (everyday vs. emergency), during indoor wayfinding in virtual environments. A virtual reality-based methodology was used. Thus, participants attempted to find a room (everyday situation) in a virtual hotel, followed by a fire-related emergency egress (emergency situation). Different behaviours were observed. In the everyday situation, for no-signs condition, participants choose mostly the wider and brighter corridors, suggesting a heavy reliance on the environmental affordances. Conversely, for signs condition, participants mostly complied with signage, suggesting a greater reliance on the signs rather than on the environmental cues. During emergency, without signage, reliance on environmental affordances seems to be affected by the intersection type. In the sign condition, the reliance on environmental affordances that started strong decreases along the egress route.

The Moravian Gate as route of migration of thermophilous bee species to Poland: fact or myth? A case study in the “Góra Gipsowa” steppe reserve and other habitats near Kietrz

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Banaszak Józef

2017-06-01

Full Text Available This study complements earlier research on wild bees (Apiformes in the “Góra Gipsowa” steppe reserve and other habitats near the town of Kietrz (SW Poland, close to the Czech border. It also attempts to reassess the opinion of some researchers about the Moravian Gate as a migration route of southern species to Poland. 109 bee species were recorded at the study sites, including 10 red-listed ones; southern species accounted for 16.5% of this number. The hypothetical route of migration of thermophilous bees through the Moravian Gate to Poland was analysed and the species composition of southern species at either side of the Moravian Gate compared. The results of this study indicate that at present the Moravian Gate plays no part in the migration of southern bee species to Poland.

The optimal choice of medication administration route regarding intravenous, intramuscular, and subcutaneous injection

Directory of Open Access Journals (Sweden)

Jin JF

2015-07-01

governing the choice of injection route. Safety and efficacy must be the preferred principles to be considered (eg, epinephrine should be given intramuscularly during an episode of systemic anaphylaxis. If the safety and efficacy of two injection routes are equivalent, clinicians should consider more about patient preference and pharmacoeconomics because patient preference will ensure optimal treatment adherence and ultimately improve patient experience or satisfaction, while pharmacoeconomic concern will help alleviate nurse shortages and reduce overall health care costs. Besides the principles, the following detailed factors might affect the decision: patient characteristics-related factors (body mass index, age, sex, medical status [eg, renal impairment, comorbidities], personal attitudes toward safety and convenience, past experience, perception of current disease status, health literacy, and socioeconomic status, medication administration-related factors (anatomical site of injection, dose, frequency, formulation characteristics, administration time, indication, flexibility in the route of administration, and health care staff/institution-related factors (knowledge, human resources.Conclusion: This updated review of findings of comparative studies of different injection routes will enrich the knowledge of safe, efficacious, economic, and patient preference-oriented medication administration as well as catching research opportunities in clinical nursing practice.Keywords: administration route, dosage and administration, efficacy, medication safety, patient preference, pharmacoeconomic

Detours in long-distance migration across the Qinghai-Tibetan Plateau: individual consistency and habitat associations.

Science.gov (United States)

Liu, Dongping; Zhang, Guogang; Jiang, Hongxing; Lu, Jun

2018-01-01

Migratory birds often follow detours when confronted with ecological barriers, and understanding the extent and the underlying drivers of such detours can provide important insights into the associated cost to the annual energy budget and the migration strategies. The Qinghai-Tibetan Plateau is the most daunting geographical barrier for migratory birds because the partial pressure of oxygen is dramatically reduced and flight costs greatly increase. We analyzed the repeated migration detours and habitat associations of four Pallas's Gulls Larus ichthyaetus across the Qinghai-Tibetan Plateau over 22 migration seasons. Gulls exhibited notable detours, with the maximum distance being more than double that of the expected shortest route, that extended rather than reduced the passage across the plateau. The extent of longitudinal detours significantly increased with latitude, and detours were longer in autumn than in spring. Compared with the expected shortest routes, proximity to water bodies increased along autumn migration routes, but detour-habitat associations were weak along spring migration routes. Thus, habitat availability was likely one, but not the only, factor shaping the extent of detours, and migration routes were determined by different mechanisms between seasons. Significant between-individual variation but high individual consistency in migration timing and routes were revealed in both seasons, indicating a stronger influence of endogenous schedules than local environmental conditions. Gulls may benefit from repeated use of familiar routes and stopover sites, which may be particularly significant in the challenging environment of the Qinghai-Tibetan Plateau.

Model complexity and choice of model approaches for practical simulations of CO₂ injection, migration, leakage and long-term fate

Energy Technology Data Exchange (ETDEWEB)

Celia, Michael A. [Princeton Univ., NJ (United States)

2016-12-30

This report documents the accomplishments achieved during the project titled “Model complexity and choice of model approaches for practical simulations of CO₂ injection,migration, leakage and long-term fate” funded by the US Department of Energy, Office of Fossil Energy. The objective of the project was to investigate modeling approaches of various levels of complexity relevant to geologic carbon storage (GCS) modeling with the goal to establish guidelines on choice of modeling approach.

Oceanic migration and spawning of anguillid eels.

Science.gov (United States)

Tsukamoto, K

2009-06-01

Many aspects of the life histories of anguillid eels have been revealed in recent decades, but the spawning migrations of their silver eels in the open ocean still remains poorly understood. This paper overviews what is known about the migration and spawning of anguillid species in the ocean. The factors that determine exactly when anguillid eels will begin their migrations are not known, although environmental influences such as lunar cycle, rainfall and river discharge seem to affect their patterns of movement as they migrate towards the ocean. Once in the ocean on their way to the spawning area, silver eels probably migrate in the upper few hundred metres, while reproductive maturation continues. Although involvement of a magnetic sense or olfactory cues seems probable, how they navigate or what routes they take are still a matter of speculation. There are few landmarks in the open ocean to define their spawning areas, other than oceanographic or geological features such as oceanic fronts or seamounts in some cases. Spawning of silver eels in the ocean has never been observed, but artificially matured eels of several species have exhibited similar spawning behaviours in the laboratory. Recent collections of mature adults and newly spawned preleptocephali in the spawning area of the Japanese eel Anguilla japonica have shown that spawning occurs during new moon periods in the North Equatorial Current region near the West Mariana Ridge. These data, however, show that the latitude of the spawning events can change among months and years depending on oceanographic conditions. Changes in spawning location of this and other anguillid species may affect their larval transport and survival, and appear to have the potential to influence recruitment success. A greater understanding of the spawning migration and the choice of spawning locations by silver eels is needed to help conserve declining anguillid species.

Deadlock Avoidance Policy in Mobile Wireless Sensor Networks with Free Choice Resource Routing

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Prasanna Ballal

2008-09-01

Full Text Available Efficient control schemes are required for effective cooperation of robot teams in a mobile wireless sensor network. If the robots (resources are also in charge of executing multiple simultaneous missions, then risks of deadlocks due to the presence of shared resources among different missions increase and have to be tackled. Discrete event control with deadlock avoidance has been used in the past for robot team coordination for the case of multi reentrant flowline models with shared resources. In this paper we present an analysis of deadlock avoidance for a generalized case of multi reentrant flow line systems (MRF called the Free Choice Multi Reentrant Flow Line systems (FMRF. In FMRF, some tasks have multiple resource choices; hence routing decisions have to be made and current results in deadlock avoidance for MRF do not hold. This analysis is based on the so-called Circular Waits (CW of the resources in the system. For FMRF, the well known notions of Critical Siphons and Critical Subsystems must be generalized and we redefine these objects for such systems. Our second contribution provides a matrix formulation that efficiently computes the objects required for deadlock avoidance in FMRF systems. A MAXWIP dispatching policy is formulated for deadlock avoidance in FMRF systems. According to this policy, deadlock in FMRF is avoided by limiting the work in progress (WIP in the critical subsystems of each CW. Implemented results of the proposed scheme in a WSN test-bed is presented in the paper.

Does Choice of Head Size and Neck Geometry Affect Stem Migration in Modular Large-Diameter Metal-on-Metal Total Hip Arthroplasty? A Preliminary Analysis.

Science.gov (United States)

Georgiou, Cs; Evangelou, Kg; Theodorou, Eg; Provatidis, Cg; Megas, Pd

2012-01-01

Due to their theoretical advantages, hip systems combining modular necks and large diameter femoral heads have gradually gained popularity. However, among others, concerns regarding changes in the load transfer patterns were raised. Recent stress analyses have indeed shown that the use of modular necks and big femoral heads causes significant changes in the strain distribution along the femur. Our original hypothesis was that these changes may affect early distal migration of a modular stem. We examined the effect of head diameter and neck geometry on migration at two years of follow-up in a case series of 116 patients (125 hips), who have undergone primary Metal-on-Metal total hip arthroplasty with the modular grit-blasted Profemur®E stem combined with large-diameter heads (>36 mm). We found that choice of neck geometry and head diameter has no effect on stem migration. A multivariate regression analysis including the potential confounding variables of the body mass index, bone quality, canal fill and stem positioning revealed only a negative correlation between subsidence and canal fill in midstem area. Statistical analysis, despite its limitations, did not confirm our hypothesis that choice of neck geometry and/or head diameter affects early distal migration of a modular stem. However, the importance of correct stem sizing was revealed.

The European Crisis and Migration to Germany: Expectations and the Diversion of Migration Flows

OpenAIRE

Brücker, Herbert; Bertoli, Simone; Fernández-Huertas Moraga, Jesús

2013-01-01

The European crisis has diverted migration flows away from countries affected by the recession towards Germany. The diversion process creates a challenge for traditional discrete-choice models that assume that only bilateral factors account for dyadic migration rates. This paper shows how taking into account the sequential nature of migration decisions leads to write the bilateral migration rate as a function of expectations about the evolution of economic conditions in alternative destinatio...

Petroleum migration pathways and charge concentration: A three-dimensional model

Energy Technology Data Exchange (ETDEWEB)

Hindle, A.D. [Anadarko Algeria Corp., Middlesex (United Kingdom)

1997-09-01

Petroleum migration pathways through a basin are determined by the three-dimensional distribution of discontinuous sealing surfaces, which are usually parallel to bedding. The petroleum migrates below the sealing surface, taking the structurally most advantageous route. The three-dimensional distribution of migration pathways within the petroleum system can be modeled on a personal computer using a program based on the parameters discussed in this paper. Application of the model to the Paris and Williston basins demonstrates that a good correlation between predicted pathways and discovered accumulations can be made using simple models. Pathways form a dense network overlying generating areas in the central parts of basins. Toward the basin margins these routes commonly become increasingly focused into discrete pathways by the sealing-surface morphologies. Eventually, these pathways may reach the surface as seepages. It is important to integrate surface outcrops of migration routes (surface seepages) into migration modeling. Deflection of the pathways from the structurally most advantageous route below the sealing surface may be caused by lateral sealing barriers due to faces variation in the carrier rock below the seal, fault juxtaposition, or cross-formational seals such as salt intrusions. Deflection of pathways also occurs where there are hydrodynamic conditions in response to topography-driven groundwater flow. Zones of vertical migration are associated with facies changes along the horizon of the sealing surface into a nonsealing facies, or juxtaposition to nonsealing strata by faults. Vertical migration from either normally or abnormally pressured strata is most likely to occur into normally or lesser pressured strata at intrabasinal highs where hydrocarbons can be stored and transferred at times of temporary seal rupture.

Strategic Choice Analysis by Expert Panels for Migration Impact Assessment

NARCIS (Netherlands)

Kourtit, K.; Nijkamp, P.

2011-01-01

International migration is a source of policy and research interest in many countries. This paper provides a review of experiences and findings from migration impact assessment worldwide. Various findings are briefly summarised in the context of a systematic migration SWOT analysis for five distinct

Map Sensitivity vs. Map Dependency: A Case Study of Subway Maps’ Impact on Passenger Route Choices in Washington DC

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John Xu

2017-10-01

Full Text Available This paper addresses the key assumption in behavioral and transportation planning literature that, when people use a transit system more frequently, they become less dependent on and less sensitive to transit maps in their decision-making. Therefore, according to this assumption, map changes are much less impactful to travel decisions of frequent riders than to that of first-time or new passengers. This assumption—though never empirically validated—has been the major hurdle for transit maps to becoming a planning tool to change passengers’ behavior. This paper examines this assumption using the Washington DC metro map as a case study by conducting a route choice experiment between 30 Origin-Destination (O-D pairs on seven metro map designs. The experiment targets two types of passengers: frequent metro riders through advertisements on a free daily newspaper available at DC metro stations, and general residents in the Washington metropolitan area through Amazon Mechanical Turk, an online crowdsourcing platform. A total of 255 and 371 participants made 2024 and 2960 route choices in the respective experiments. The results show that frequent passengers are in fact more sensitive to subtle changes in map design than general residents who are less likely to be familiar with the metro map and therefore unaffected by map changes presented in the alternative designs. The work disproves the aforementioned assumption and further validates metro maps as an effective planning tool in transit systems.

The metrics and correlates of physician migration from Africa

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Arah Onyebuchi A

2007-05-01

Full Text Available Abstract Background Physician migration from poor to rich countries is considered an important contributor to the growing health workforce crisis in the developing world. This is particularly true for Africa. The perceived magnitude of such migration for each source country might, however, depend on the choice of metrics used in the analysis. This study examined the influence of choice of migration metrics on the rankings of African countries that suffered the most physician migration, and investigated the correlates of physician migration. Methods Ranking and correlational analyses were conducted on African physician migration data adjusted for bilateral net flows, and supplemented with developmental, economic and health system data. The setting was the 53 African birth countries of African-born physicians working in nine wealthier destination countries. Three metrics of physician migration were used: total number of physician émigrés; emigration fraction defined as the proportion of the potential physician pool working in destination countries; and physician migration density defined as the number of physician émigrés per 1000 population of the African source country. Results Rankings based on any of the migration metrics differed substantially from those based on the other two metrics. Although the emigration fraction and physician migration density metrics gave proportionality to the migration crisis, only the latter was consistently associated with source countries' workforce capacity, health, health spending, economic and development characteristics. As such, higher physician migration density was seen among African countries with relatively higher health workforce capacity (0.401 ≤ r ≤ 0.694, p ≤ 0.011, health status, health spending, and development. Conclusion The perceived magnitude of physician migration is sensitive to the choice of metrics. Complementing the emigration fraction, the physician migration density is a metric

Solving a bi-objective vehicle routing problem under uncertainty by a revised multi-choice goal programming approach

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Hossein Yousefi

2017-06-01

Full Text Available A vehicle routing problem with time windows (VRPTW is an important problem with many real applications in a transportation problem. The optimum set of routes with the minimum distance and vehicles used is determined to deliver goods from a central depot, using a vehicle with capacity constraint. In the real cases, there are other objective functions that should be considered. This paper considers not only the minimum distance and the number of vehicles used as the objective function, the customer’s satisfaction with the priority of customers is also considered. Additionally, it presents a new model for a bi-objective VRPTW solved by a revised multi-choice goal programming approach, in which the decision maker determines optimistic aspiration levels for each objective function. Two meta-heuristic methods, namely simulated annealing (SA and genetic algorithm (GA, are proposed to solve large-sized problems. Moreover, the experimental design is used to tune the parameters of the proposed algorithms. The presented model is verified by a real-world case study and a number of test problems. The computational results verify the efficiency of the proposed SA and GA.

Implantable central venous chemoport: camparision of results according to approach routes and methods

International Nuclear Information System (INIS)

Shin, Byung Suck; Ahn, Moon Sang

2003-01-01

To evaluate the results and complications of placement of implantable port according to approach routes and methods. Between April 2001 and October 2002, a total of 103 implantable chemoport was placed in 95 patients for chemotherapy using preconnected type (n=39) and attachable type (n=64). Puncture sites were left subclavian vein (n=35), right subclavian vein (n=5), left internal jugular vein (n=9), right internal jugular vein (n=54). We evaluated duration of catheterization days, complications according to approach routes and methods. Implantable chemoport was placed successfully in all cases. Duration of catheterization ranged from 8 to 554 days(mean 159, total 17,872 catheter days). Procedure related complications occurred transient pulmonary air embolism (n=1), small hematoma (n=1) and malposition in using preconnected type (n=2). Late complications occurred catheter migration (n=5), catheter malfunction (n=3), occlusion (n=1) and infection (n=11). Among them 15 chemoport was removed (14.5%). Catheter migration was occured via subclavian vein in all cases (13%, p=.008). Infection developed in 10.7% of patients(0.61 per 1000 catheter days). There were no catheter-related central vein thrombosis. Implantation of chemoport is a safe procedure. Choice of right internal jugular vein than subclavian vain vein for puncture site has less complications. And selection of attachable type of chemoport is convenient than preconnected type. Adequate care of chemoport is essential for long patency

Channel Choice: A Literature Review

DEFF Research Database (Denmark)

Østergaard Madsen, Christian; Kræmmergaard, Pernille

2015-01-01

The channel choice branch of e-government studies citizens’ and businesses’ choice of channels for interacting with government, and how government organizations can integrate channels and migrate users towards the most cost-efficient channels. In spite of the valuable contributions offered...

Mean Velocity Prediction Information Feedback Strategy in Two-Route Systems under ATIS

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Jianqiang Wang

2015-02-01

Full Text Available Feedback contents of previous information feedback strategies in advanced traveler information systems are almost real-time traffic information. Compared with real-time information, prediction traffic information obtained by a reliable and effective prediction algorithm has many undisputable advantages. In prediction information environment, a traveler is prone to making a more rational route-choice. For these considerations, a mean velocity prediction information feedback strategy (MVPFS is presented. The approach adopts the autoregressive-integrated moving average model (ARIMA to forecast short-term traffic flow. Furthermore, prediction results of mean velocity are taken as feedback contents and displayed on a variable message sign to guide travelers' route-choice. Meanwhile, discrete choice model (Logit model is selected to imitate more appropriately travelers' route-choice behavior. In order to investigate the performance of MVPFS, a cellular automaton model with ARIMA is adopted to simulate a two-route scenario. The simulation shows that such innovative prediction feedback strategy is feasible and efficient. Even more importantly, this study demonstrates the excellence of prediction feedback ideology.

Revealed Preference Methods for Studying Bicycle Route Choice—A Systematic Review

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Ray Pritchard

2018-03-01

Full Text Available One fundamental aspect of promoting utilitarian bicycle use involves making modifications to the built environment to improve the safety, efficiency and enjoyability of cycling. Revealed preference data on bicycle route choice can assist greatly in understanding the actual behaviour of a highly heterogeneous group of users, which in turn assists the prioritisation of infrastructure or other built environment initiatives. This systematic review seeks to compare the relative strengths and weaknesses of the empirical approaches for evaluating whole journey route choices of bicyclists. Two electronic databases were systematically searched for a selection of keywords pertaining to bicycle and route choice. In total seven families of methods are identified: GPS devices, smartphone applications, crowdsourcing, participant-recalled routes, accompanied journeys, egocentric cameras and virtual reality. The study illustrates a trade-off in the quality of data obtainable and the average number of participants. Future additional methods could include dockless bikeshare, multiple camera solutions using computer vision and immersive bicycle simulator environments.

Migration patterns and movements of sandhill cranes wintering in central and southwestern Louisiana

Science.gov (United States)

King, Sammy L.; Pierce, Aaron R.; Hersey, Kent R.; Winstead, Nicholas; Hartup, Barry K.

2010-01-01

In this study we trapped wintering sandhill cranes (Grus canadensis) in Louisiana and fitted them with satellite transmitters to determine their migration routes. Four of the 6 sandhill cranes with validated locations and a terminus point used the Central Flyway for spring migration; 2 of these 4 (the only 2 for which we have data) also used the Central Flyway for fall migration. Two of the 6 birds used the Mississippi Flyway for spring migration. The results of this study suggest that reintroduced whooping cranes (G. americana) that intermix and migrate with sandhill cranes that winter in Louisiana may enter the Central Flyway. In addition, the Mississippi Flyway is a viable option to use as a migration route for whooping cranes if they are reintroduced in Louisiana.

Flexible navigation response in common cuckoos Cuculus canorus displaced experimentally during migration

DEFF Research Database (Denmark)

Willemoes, Mikkel; Blas, Julio; Wikelski, Martin

2015-01-01

Migrating birds follow innate species-specific migration programs capable of guiding them along complex spatio-temporal routes, which may include several separate staging areas. Indeed, migration routes of common cuckoos Cuculus canorus show little variation between individuals; yet, satellite...... tracks of 11 experimentally displaced adults revealed an unexpected flexibility in individual navigation responses. The birds compensated for the translocation to unfamiliar areas by travelling toward population-specific staging areas, demonstrating true navigation capabilities. Individual responses...

Channels to West: Exploring the Migration Routes between Romania and France

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Marius Lupșa Matichescu

2017-10-01

Full Text Available The integration of East European Countries in European Union has long-term consequences, with migration being one of the main social effects of this process. From an economic perspective, the research on migration has attracted considerable attention, whereas the analyses focused on the social networks are more scarce. The importance of these social networks becomes more substantial due to their quality and ability to reduce costs, risks of movement and uncertainty. Although the migratory networks are known at national levels, there are very few data related to the territorial distribution of migration network between origin and destination areas. In this context, Romania registered the highest level of emigration toward Western European countries, and this case study offers illustrative insights for the broader literature. In order to illustrate the territorial distribution of migrants’ network between Romania and France, we used an exhaustive analysis of the trajectories of all clients who used one of the largest transport companies operating between Romania and France (8094 cases. Using the benefits of this evidence-based approach, we identified the regions and the Romanian towns most affected by the migration phenomenon. Complementary, we illustrated the territorial distribution and the preferred destination regions in France for the Romanian immigrants. We present the migration networks that exist between the towns of the two countries and identify the intensity of each migration circuit.

Narrow-front loop migration in a population of the common cuckoo Cuculus canorus, as revealed by satellite telemetry.

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Mikkel Willemoes

Full Text Available Narrow migration corridors known in diurnal, social migrants such as raptors, storks and geese are thought to be caused by topographical leading line effects in combination with learning detailed routes across generations. Here, we document narrow-front migration in a nocturnal, solitary migrant, the common cuckoo Cuculus canorus, using satellite telemetry. We tracked the migration of adult cuckoos from the breeding grounds in southern Scandinavia (n = 8, to wintering sites in south-western Central Africa (n = 6 and back to the breeding grounds (n = 3. Migration patterns were very complex; in addition to the breeding and wintering sites, six different stopover sites were identified during the 16,000 km annual route that formed a large-scale clockwise loop. Despite this complexity, individuals showed surprisingly similar migration patterns, with very little variation between routes. We compared observed tracks with simulated routes based on vector orientation (with and without effects of barriers on orientation and survival. Observed distances between routes were often significantly smaller than expected if the routes were established on the basis of an innate vector orientation programme. Average distance between individuals in eastern Sahel after having migrated more than 5,000 km for example, was merely 164 km. This implies that more sophisticated inherent guiding mechanisms, possibly involving elements of intermediate goal area navigation or more elaborate external cues, are necessary to explain the complex narrow-front migration pattern observed for the cuckoos in this study.

Motorized Migrations: the Future or Mere Fantasy?

Science.gov (United States)

Ellis, D.H.; Sladen, William J. L.; Lishman, W.A.; Clegg, K.R.; Duff, J.W.; Gee, G.F.; Lewis, J.C.

2003-01-01

In 15 experiments from 1993-2002, we led cranes, geese, or swans on their first southward migration with either ultralight aircraft or vehicles on the ground. These experiments reveal that large birds can be readily trained to follow and most will return north (and south) in subsequent migrations unassisted. These techniques can now be used to teach birds new (or forgotten) migration paths. Although we are constantly improving our training techniques, we now have an operational program that can be broadly applied to those species where juveniles learn migration routes from their parents.

Tracking from the tropics reveals behaviour of juvenile songbirds on their first spring migration.

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Emily A McKinnon

Full Text Available Juvenile songbirds on spring migration travel from tropical wintering sites to temperate breeding destinations thousands of kilometres away with no prior experience to guide them. We provide a first glimpse at the migration timing, routes, and stopover behaviour of juvenile wood thrushes (Hylocichla mustelina on their inaugural spring migration by using miniaturized archival geolocators to track them from Central America to the U.S. and Canada. We found significant differences between the timing of juvenile migration and that of more experienced adults: juveniles not only departed later from tropical wintering sites relative to adults, they also became progressively later as they moved northward. The increasing delay was driven by more frequent short stops by juveniles along their migration route, particularly in the U.S. as they got closer to breeding sites. Surprisingly, juveniles were just as likely as adults to cross the Gulf of Mexico, an open-water crossing of 800-1000 km, and migration route at the Gulf was not significantly different for juveniles relative to adults. To determine if the later departure of juveniles was related to poor body condition in winter relative to adults, we examined percent lean body mass, fat scores, and pectoral muscle scores of juvenile versus adult birds at a wintering site in Belize. We found no age-related differences in body condition. Later migration timing of juveniles relative to adults could be an adaptive strategy (as opposed to condition-dependent to avoid the high costs of fast migration and competition for breeding territories with experienced and larger adults. We did find significant differences in wing size between adults and juveniles, which could contribute to lower flight efficiency of juveniles and thus slower overall migration speed. We provide the first step toward understanding the "black box" of juvenile songbird migration by documenting their migration timing and en route performance.

In-Migration and Housing Choice in Ho Chi Minh City: Toward Sustainable Housing Development in Vietnam

Directory of Open Access Journals (Sweden)

Ducksu Seo

2017-09-01

Full Text Available Since the initiation of Vietnam’s Doi Moi policy in 1986, the rate of urbanization has rapidly increased with a great influx of immigrants from rural areas. With such migration becoming a large acceleration factor for urban growth, the shortage of housing has become a critical problem in the cities. The Vietnamese government encouraged self-built housing and public–private partnerships to produce different types of housing stock. There are few available academic studies about housing choice in Vietnam to help understand movement dynamics and to foster sustainable housing development. The purpose of this study is to analyze housing choice and moving determinants in Ho Chi Minh City, and thereby establish recommendations for sustainable housing development in Vietnam. For an empirical study, a citizen questionnaire survey was conducted in HCMC and an in-depth analysis was carried out. The results indicate that the row house type for single-family housing is strongly preferred, but a preference for apartments is also observed for future planning. The factors influencing housing choice and movement are family income, housing ownership, housing typology, and commuting environment. These phenomena suggest that the government should prudently consider affordable housing development in many districts. The results of this study will help to establish policies for sustainable housing development in Ho Chi Minh City, Vietnam.

Roosts and migrations of swallows

OpenAIRE

Winkler, David W.

2006-01-01

Swallows of the north temperate zone display a wide variety of territorial behaviour during the breeding season, but as soon as breeding is over, they all appear to adopt a pattern of independent diurnal foraging interleaved with aggregation every night in dense roosts. Swallows generally migrate during the day, feeding on the wing. On many stretches of their annual journeys, their migrations can thus be seen as the simple spatial translation of nocturnal roost sites with foraging routes stra...

Selection of highway routes for the shipment of radioactive materials within the Commonwealth of Virginia

International Nuclear Information System (INIS)

Hobeika, A.G.; Jamei, B.; Santoso, I.B.

1986-01-01

In this study Virginia Electric and Power Company proposed to ship limited quantities of irradiated nuclear fuel from Surry to North Anna in Virginia. Eight routes were considered as candidate routes for shipment. The objectives of this study are: To minimize the accidental-release radiation risk to people and property; and to maximize the community preparedness in terms of emergency response and evacuation capability. To determine the ''Preferred'' route and the alternative route for highway shipments of radioactive material, a conceptual approach was developed, based on the following three principles: Feasibility; Evaluation; and Choice. The feasibility of a candidate route is first established. Then all feasible routes are evaluated under the same criteria, which would lead to the choice of the best feasible route

Fish ladder of Lajeado Dam: migrations on one-way routes?

Directory of Open Access Journals (Sweden)

Angelo Antônio Agostinho

Full Text Available Fish ladders are generally conceived to reestablish connectivity among critical habitats for migratory species, thus mitigating the impacts of the blockage of migration routes by dams. If this management tool is to be meaningful for conserving fish species, it must provide a fully permeable connection and assure both upward and downward movements. However, because reservoirs have very different hydrodynamics than the original river, it is expected that, at least in the inner area, they may constitute an additional barrier to this movement, especially for descending fish. Thus, the present study sought to determine if migratory fish and their offspring disperse downstream from the dam after ascending a ladder and spawning in the upper reaches of a basin. To achieve this purpose, we evaluated the limitation imposed by lentic areas to the descent of eggs, larvae and adults of migratory species; we also determined the abundance and composition of larvae present in the plankton near the dam, and compared the intensity of the upward and downward movements of adult fish. Samples of ichthyoplankton were taken upriver, inside the reservoir, in the river downstream from the dam, and in the forebay of the Lajeado Dam on the Tocantins River (Luis Eduardo Magalhães Hydroelectric Plant, from October, 1999 through September, 2004. The densities of fish ascending and descending the ladder were determined experimentally on eight occasions, from June, 2004 to March, 2005. Due to difficulties in identifying the true fish origin (up or down in the environments connected by the fish passage system, the evaluation of the distribution of migratory fish in reservoirs was based on the landings of the commercial fishery conducted along the Itaipu Reservoir during the four years preceding (2001 through 2003 the construction of the lateral channel (fish-passage mechanism. Fish eggs and larvae drifting down the Tocantins River did not appear in samples taken in the lower

[Identification and sampling of people with migration background for epidemiological studies in Germany].

Science.gov (United States)

Reiss, K; Makarova, N; Spallek, J; Zeeb, H; Razum, O

2013-06-01

In 2009, 19.6% of the population of Germany either had migrated themselves or were the offspring of people with migration experience. Migrants differ from the autochthonous German population in terms of health status, health awareness and health behaviour. To further investigate the health situation of migrants in Germany, epidemiological studies are needed. Such studies can employ existing databases which provide detailed information on migration status. Otherwise, onomastic or toponomastic procedures can be applied to identify people with migration background. If migrants have to be recruited into an epidemiological study, this can be done register-based (e. g., data from registration offices or telephone lists), based on residential location (random-route or random-walk procedure), via snowball sampling (e. g., through key persons) or via settings (e. g., school entry examination). An oversampling of people with migration background is not sufficient to avoid systematic bias in the sample due to non-participation. Additional measures have to be taken to increase access and raise participation rates. Personal contacting, multilingual instruments, multilingual interviewers and extensive public relations increase access and willingness to participate. Empirical evidence on 'successful' recruitment strategies for studies with migrants is still lacking in epidemiology and health sciences in Germany. The choice of the recruitment strategy as well as the measures to raise accessibility and willingness to participate depend on the available resources, the research question and the specific migrant target group. © Georg Thieme Verlag KG Stuttgart · New York.

Radionuclide-migration model for buried waste at the Savannah River Plant

International Nuclear Information System (INIS)

King, C.M.; Root, R.W. Jr.

1982-01-01

Solid waste has been buried at the Savannah River Plant burial ground since 1953. The solid waste is contaminated with alpha-emitting transuranium (TRU) nuclides, with beta-gamma-emitting activation and fission products, and with tritium. To provide guidance for the current use and eventual permanent retirement of the burial site from active service, a radionuclide environmental transport model has been used to project the potential influence on man if the burial site were occupied after decommissioning. The model used to simulate nuclide migration includes the various hydrological, animal, vegetative, atmospheric, and terrestrial pathways in estimating dose to man as a function of time. Specific scenarios include a four-person home farm on the 195-acre burial ground. Key input to the model includes site-specific nuclide migration rates through soil, nuclide distribution coefficients, and site topography. Coupled with literature data on plant and animal concentration factors, transfer coefficients reflecting migration routes are input to a set of linear differential equations for subsequent matrix solution. Output from the model is the nuclide-specific decayed curie intake by man. To discern principal migration routes, model-compartment inventories with time can also be displayed. Dose projections subsequently account for organ concentrations in man for the nuclide of interest. Radionuclide migration has been examined in depth with the dose-to-man model. Movement by vegetative pathways is the primary route for potential dose to man for short-lived isotopes. Hydrological routes provide a secondary scheme for long-lived nuclides. Details of model methodology are reviewed

Empirical analyses of a choice model that captures ordering among attribute values

DEFF Research Database (Denmark)

Mabit, Stefan Lindhard

2017-01-01

an alternative additionally because it has the highest price. In this paper, we specify a discrete choice model that takes into account the ordering of attribute values across alternatives. This model is used to investigate the effect of attribute value ordering in three case studies related to alternative-fuel...... vehicles, mode choice, and route choice. In our application to choices among alternative-fuel vehicles, we see that especially the price coefficient is sensitive to changes in ordering. The ordering effect is also found in the applications to mode and route choice data where both travel time and cost...

Feminization of Migration Routes and Integration Aspects in Trieste Area and Friuli-Venezia Giulia Region

Directory of Open Access Journals (Sweden)

Melita Richter Malabotta

2002-12-01

Full Text Available Italian society is going through deep structural demographic and cultural changes whereby its emigration pattern has been reversed to the extent that the country is now experiencing intensive immigration. Pre-supposing the two basic characteristics of the migration routes which have become visible in the last decade – namely feminization and internal diversification of universal migrant, this article has tried to show the market typology (a characteristic not only of Italy but other Mediterranean countries of the EU which contributes to the gender differentiation of the foreigners' work, paying special attention to the position of an immigrant woman in the integration process into the native community. In that context, the analysis is directed towards the Friuli-Venezia Giulia Region and the town of Trieste which have proved themselves to be unique in their acceptance of newcomers, among whom the most numerous being the ex-Yugoslavian (mainly Serbian population. Issues which have been touched include the recent history of dynamic Italian-Yugoslav relationships, the importance of the border, the daily cross-border migration mostly performed by the female workforce and the multiculturalism of Trieste as a border town. The so-called stable migration going through “family unification” has also been observed, a process responsible for the constant rise in the numbers of immigrant women and their underage children. In the way of their harmonic integration into the new society stand numerous obstacles: the language barrier, prejudice, the social invisibility of foreign women, their domestication, professional disqualification and coerced collective identity enforced by national or monoethnic associations. In school – an institution that forms a relationship with the foreign students’ mothers – attempts are being made to break free from this state of social invisibility. Similarly, in multicultural associations and societies, immigrant women

Tracking the Autumn Migration of the Bar-Headed Goose (Anser indicus with Satellite Telemetry and Relationship to Environmental Conditions

Directory of Open Access Journals (Sweden)

Yaonan Zhang

2011-01-01

Full Text Available The autumn migration routes of bar-headed geese captured before the 2008 breeding season at Qinghai Lake, China, were documented using satellite tracking data. To assess how the migration strategies of bar-headed geese are influenced by environmental conditions, the relationship between migratory routes, temperatures, and vegetation coverage at stopovers sites estimated with the Normalized Difference Vegetation Index (NDVI were analyzed. Our results showed that there were four typical migration routes in autumn with variation in timing among individuals in start and end times and in total migration and stopover duration. The observed variation may be related to habitat type and other environmental conditions along the routes. On average, these birds traveled about 1300 to 1500 km, refueled at three to six stopover sites and migrated for 73 to 83 days. The majority of the habitat types at stopover sites were lake, marsh, and shoal wetlands, with use of some mountainous regions, and farmland areas.

Inclusive growth?: Labour migration and poverty in India

OpenAIRE

Haan, Arjan

2011-01-01

textabstractThis paper discusses the relationship between labour migration and poverty in India. This is placed against the on-going debates on changes in patterns of employment and job creation in India, during the periods of economic liberalization, under the Inclusive Growth policies since 2004, and under the impact of the global financial crisis, and growing inequalities. The paper focuses on the migration patterns of deprived social groups, analyse whether migration form a routes out of ...

Fish Species in a Changing World: The Route and Timing of Species Migration between Tropical and Temperate Ecosystems in Eastern Atlantic.

Directory of Open Access Journals (Sweden)

Awaluddin Halirin Kaimuddin

2016-09-01

Full Text Available The presence of tropical species has been reported in Atlantic-European waters with increasing frequency in recent years. Unfortunately, the history of their migrations is not well understood. In this study, we examined the routes and timing of fish migrations in several ecosystems of the East Atlantic Ocean, combining several publicly available and unpublicized datasets on species occurrences. The species studied were those noted as exotic or rare outside their previous known area of distribution. We used sea surface temperature (SST data obtained from 30 years of satellite observation to define three distinct time periods. Within these periods, temperature trends were studied in six ecosystems: the North Sea, the Celtic Sea, the South European Atlantic Waters, the Mediterranean Sea, the Canary Current and the Guinea Current. We also incorporated bathymetry data to describe the distribution of species. Measurement across a relatively large spatial extent was made possible by incorporating the capabilities of GIS.While SST increased consistently over time in all of the ecosystems observed, the change in number of species differed among ecosystems. The number of species in the middle regions, such as the South European Atlantic Shelf and the Western Mediterranean Sea, tended to increase over time. These regions received numbers of species from the lower or the upper latitudes according to season. Of all of the species observed in the recent period, 7 species from the Canary Current tended to be found in the Western Mediterranean Sea, and 6 species from these two regions extended their distributions to the South European Atlantic Shelf. Twelve species from the Canary Current moved seasonally to the Guinea Current. In the northern regions, 13 species moved seasonally in the North Sea and the Celtic Seas, and 12 of these species reached the South European Atlantic Shelf.This study presents a picture of routes and timing of species migration at the

One year of migration data for a western yellow-billed cuckoo

Science.gov (United States)

Sechrist, Juddson D.; Paxton, Eben H.; Ahlers, Darrell D.; Doster, Robert H.; Ryan, Vicky M.

2012-01-01

In 2009, we studied the migration of the Western Yellow-billed Cuckoo by capturing 13 breeding birds on the middle Rio Grande, New Mexico, and attaching a 1.5-g Mk 14-S British Antarctic Survey geolocator to each bird. In 2010, we recaptured one of the cuckoos, enabling us to download its geolocation data. The cuckoo had flown approximately 9500 km during its southward migration, traveling through Central America to winter in portions of Bolivia, Brazil, Paraguay, and Argentina. The spring migration route differed somewhat from the fall route, with the cuckoo bypassing Central America to migrate through the Caribbean. Additionally, it moved between New Mexico and Mexico at the end of summer in 2009 and again in 2010 before being recaptured at its breeding site. Our results, albeit from one individual, hint at a dynamic migration strategy and have broad implications for the ecology and conservation of the Western Yellow-billed Cuckoo, a species of conservation concern.

Efficiency of choice set generation methods for bicycle routes

DEFF Research Database (Denmark)

Halldórsdóttir, Katrín; Rieser-Schussler, Nadine; Axhausen, Kay W.

2014-01-01

for scenic routes, dedicated cycle lanes, and road type. Data consisted of 778 bicycle trips traced by GPS and carried out by 139 persons living in the Greater Copenhagen Area, in Denmark. Results suggest that both the breadth first search on link elimination and the doubly stochastic generation function...

Were rivers flowing across the Sahara during the last interglacial? Implications for human migration through Africa.

Directory of Open Access Journals (Sweden)

Tom J Coulthard

Full Text Available Human migration north through Africa is contentious. This paper uses a novel palaeohydrological and hydraulic modelling approach to test the hypothesis that under wetter climates c.100,000 years ago major river systems ran north across the Sahara to the Mediterranean, creating viable migration routes. We confirm that three of these now buried palaeo river systems could have been active at the key time of human migration across the Sahara. Unexpectedly, it is the most western of these three rivers, the Irharhar river, that represents the most likely route for human migration. The Irharhar river flows directly south to north, uniquely linking the mountain areas experiencing monsoon climates at these times to temperate Mediterranean environments where food and resources would have been abundant. The findings have major implications for our understanding of how humans migrated north through Africa, for the first time providing a quantitative perspective on the probabilities that these routes were viable for human habitation at these times.

The dynamics of user perception, decision making and route choice

NARCIS (Netherlands)

Vreeswijk, Jacob Dirk

2015-01-01

Travellers’ response to performance changes in the traffic system is a decisive factor in the effectiveness of traffic management measures. This thesis provides an empirical and quantitative assessment of choice behaviour and the effects of perception error on choice outcomes. It considers users’

Route selection issues for NWPA shipments

International Nuclear Information System (INIS)

Hill, C.V.; Harrison, I.G.

1993-01-01

Questions surrounding the designation of routes for the movement of spent nuclear fuel (SNF) and high-level radioactive waste (HLW) by the Office of Civilian Radioactive Waste Management (OCRWM) have broad implications. Federal regulations prescribe rules to be applied in the selection of highway routes. In most cases, these rules will lead to a clear selection of one route between an origin and destination point. However, in other cases, strict application of the regulations does not result in a clear choice of a preferred route. The regulations also provide discretion to State governments and carriers to select alternative routes to enhance the safety of the shipment. Railroad shipments of radioactive materials are not subject to Federal routing regulations. Since the railroads operate on private property, it has been assumed that they know the best way to move freight on their system. This discretion, while desirable for addressing unique local safety concerns or for responding to temporary safety concerns such as road problems, weather conditions, or construction areas, leads to significant opportunity for misunderstandings and uneasiness on the part of local residents

Quantum chemistry-assisted synthesis route development

International Nuclear Information System (INIS)

Hori, Kenji; Sumimoto, Michinori; Murafuji, Toshihiro

2015-01-01

We have been investigating “quantum chemistry-assisted synthesis route development” using in silico screenings and applied the method to several targets. Another example was conducted to develop synthesis routes for a urea derivative, namely 1-(4-(trifluoromethyl)-2-oxo-2H-chromen-7-yl)urea. While five synthesis routes were examined, only three routes passed the second in silico screening. Among them, the reaction of 7-amino-4-(trifluoromethyl)-2H-chromen-2-one and O-methyl carbamate with BF 3 as an additive was ranked as the first choice for synthetic work. We were able to experimentally obtain the target compound even though its yield was as low as 21 %. The theoretical result was thus consistent with that observed. The summary of transition state data base (TSDB) is also provided. TSDB is the key to reducing time of in silico screenings

Human risk assessment of dermal and inhalation exposures to chemicals assessed by route-to-route extrapolation: the necessity of kinetic data.

Science.gov (United States)

Geraets, Liesbeth; Bessems, Jos G M; Zeilmaker, Marco J; Bos, Peter M J

2014-10-01

In toxicity testing the oral route is in general the first choice. Often, appropriate inhalation and dermal toxicity data are absent. Risk assessment for these latter routes usually has to rely on route-to-route extrapolation starting from oral toxicity data. Although it is generally recognized that the uncertainties involved are (too) large, route-to-route extrapolation is applied in many cases because of a strong need of an assessment of risks linked to a given exposure scenario. For an adequate route-to-route extrapolation the availability of at least some basic toxicokinetic data is a pre-requisite. These toxicokinetic data include all phases of kinetics, from absorption (both absorbed fraction and absorption rate for both the starting route and route of interest) via distribution and biotransformation to excretion. However, in practice only differences in absorption between the different routes are accounted for. The present paper demonstrates the necessity of route-specific absorption data by showing the impact of its absence on the uncertainty of the human health risk assessment using route-to-route extrapolation. Quantification of the absorption (by in vivo, in vitro or in silico methods), particularly for the starting route, is considered essential. Copyright © 2014 Elsevier Inc. All rights reserved.

Tour Route Multiobjective Optimization Design Based on the Tourist Satisfaction

OpenAIRE

Yan Han; Hongzhi Guan; Jiaying Duan

2014-01-01

The question prompted is how to design the tour route to make the tourists get the maximum satisfactions considering the tourists’ demand. The influence factors of the tour route choices of tourists were analyzed and tourists’ behavior characteristics and psychological preferences were regarded as the important influence factors based on the tourist behavioral theories. A questionnaire of tourists’ tour route information and satisfaction degree was carried out. Some information about the scen...

The QKD network: model and routing scheme

Science.gov (United States)

Yang, Chao; Zhang, Hongqi; Su, Jinhai

2017-11-01

Quantum key distribution (QKD) technology can establish unconditional secure keys between two communicating parties. Although this technology has some inherent constraints, such as the distance and point-to-point mode limits, building a QKD network with multiple point-to-point QKD devices can overcome these constraints. Considering the development level of current technology, the trust relaying QKD network is the first choice to build a practical QKD network. However, the previous research didn't address a routing method on the trust relaying QKD network in detail. This paper focuses on the routing issues, builds a model of the trust relaying QKD network for easily analysing and understanding this network, and proposes a dynamical routing scheme for this network. From the viewpoint of designing a dynamical routing scheme in classical network, the proposed scheme consists of three components: a Hello protocol helping share the network topology information, a routing algorithm to select a set of suitable paths and establish the routing table and a link state update mechanism helping keep the routing table newly. Experiments and evaluation demonstrates the validity and effectiveness of the proposed routing scheme.

Migration routes and staging areas of Abdim's Storks Ciconia ...

African Journals Online (AJOL)

This paper presents the results of a satellite tracking study of seven adult Abdim's Storks Ciconia abdimii that were followed from the nesting areas in southern Niger across the equator to the non-breeding range and back. Post-breeding migration started between early November and early December when all birds ...

Migrations to Ankara by Railway and Settlement Policy (1890-1910

Directory of Open Access Journals (Sweden)

İhsan Seddar Kaynar

2016-06-01

Full Text Available The Anatolian Railway began running between Ankara and Haydarpaşa in Istanbul via İzmit and Eskişehir in early 1893, making transportation from Istanbul to the interior of Anatolia very easy. In late 1892, before the railroad was opened, policymakers prepared official reports on the resettlement of migrants along the rail route from Eskişehir to Ankara; and made regulations accordingly. This studyexamines the route of this migration, which first run to the port of İzmit by sea and then reached Ankara by rail. This article discusses the politics of resettlement and the conditions of migrants settled on the railway route during the twenty-year period between 1890 and 1910, when the Balkan Wars provoked mass migration to Anatolia from the Balkans. It analyzes the locations of the new settlements, the conditions in newly founded villages, and the habitability of the wasteland along the railway route. Daily rations, state aid for housing, types of production, agricultural styles, and the position of artisans will also be considered.

Truck Route Choice Modeling using Large Streams of GPS Data

Science.gov (United States)

2017-07-31

The primary goal of this research was to use large streams of truck-GPS data to analyze travel routes (or paths) chosen by freight trucks to travel between different origin and destination (OD) location pairs in metropolitan regions of Florida. Two s...

Influence of queue propagation and dissipation on route travel times

DEFF Research Database (Denmark)

Raovic, Nevena

into account (Bliemer, 2008). Yperman (2007) indicates that there is a significant difference in queue-propagation and queue-dissipation between the LTM and DQM. This results in different route travel times, and can further affect route choice. In this paper, different approaches to represent queue propagation...... and dissipation through the CTM, LTM and DQM are studied. A simple network allows to show how these approaches influence route travel time. Furthermore, the possibility of changing the existing DQM is considered in order to more realistically represent queue propagation and dissipation, which would lead to more...... accurate route travel times....

Direct observations of American eels migrating across the continental shelf to the Sargasso Sea.

Science.gov (United States)

Béguer-Pon, Mélanie; Castonguay, Martin; Shan, Shiliang; Benchetrit, José; Dodson, Julian J

2015-10-27

Since inferring spawning areas from larval distributions in the Sargasso Sea a century ago, the oceanic migration of adult American eels has remained a mystery. No adult eel has ever been observed migrating in the open ocean or in the spawning area. Here, we track movements of maturing eels equipped with pop-up satellite archival tags from the Scotian Shelf (Canada) into the open ocean, with one individual migrating 2,400 km to the northern limit of the spawning site in the Sargasso Sea. The reconstructed routes suggest a migration in two phases: one over the continental shelf and along its edge in shallow waters; the second in deeper waters straight south towards the spawning area. This study is the first direct evidence of adult Anguilla migrating to the Sargasso Sea and represents an important step forward in the understanding of routes and migratory cues.

Bicriterion a priori route choice in stochastic time-dependent networks

DEFF Research Database (Denmark)

Nielsen, Lars Relund; Andersen, Kim Allan; Pretolani, Daniele

In recent years there has been a growing interest in using stochastic time-dependent (STD) networks as a modelling tool for a number of applications within such areas as transportation and telecommunications. It is known that an optimal routing policy does not necessarily correspond to a path...

Bicriterion a priori route choice in stochastic time-dependent networks

DEFF Research Database (Denmark)

Nielsen, Lars Relund; Pretolani, D; Andersen, K A

2006-01-01

In recent years there has been a growing interest in using stochastic time-dependent (STD) networks as a modelling tool for a number of applications within such areas as transportation and telecommunications. It is known that an optimal routing policy does not necessarily correspond to a path...

MR imaging of neuronal migration anomaly

International Nuclear Information System (INIS)

Hong, Hyun Sook; Choi, Eun Wan; Kim, Dae Ho; Chung, Moo Chan; Kwon, Kuy Hyang; Kim, Ki Jung

1991-01-01

Abnormalities of neuronal migration are characterized by anectopic location of neurons in the cerebral cortex. This broad group of anomalies includes agyria, pachygyria, schizencephaly, unilateral megalencephaly, and gray matter heterotopia. Patients with this anomaly present clinically with a variety of symptoms which are proportional to the extent of the brain involved. These abnormalities have characterized pathologically in vivo by sonography and CT scan. MR appears to be an imaging technique of choice in evaluating these anomalies because it is capable of exceptionally good differentiation between gray and white matter, high contrast resolution, multiplanar display of the anatomy, and lack of overlying bone artifac. The purpose of this paper is to describe the MR findings of neuronal migration anomaly. The results of our study support that MR appears to be the imaging method of choice for diagnosing migration anomalies and the primary screening method for infants or children who have seisure/and delayed development

Integrating routing decisions in public transportation problems

CERN Document Server

Schmidt, Marie E

2014-01-01

This book treats three planning problems arising in public railway transportation planning: line planning, timetabling, and delay management, with the objective to minimize passengers’ travel time. While many optimization approaches simplify these problems by assuming that passengers’ route choice is independent of the solution, this book focuses on models which take into account that passengers will adapt their travel route to the implemented planning solution. That is, a planning solution and passengers’ routes are determined and evaluated simultaneously. This work is technically deep, with insightful findings regarding complexity and algorithmic approaches to public transportation problems with integrated passenger routing. It is intended for researchers in the fields of mathematics, computer science, or operations research, working in the field of public transportation from an optimization standpoint. It is also ideal for students who want to gain intuition and experience in doing complexity proofs ...

Modeling the Equilibrium Bus Line Choice Behavior and Transit System Design with Oblivious Users

Directory of Open Access Journals (Sweden)

Chuan-Lin Zhao

2014-01-01

Full Text Available In most of transportation literature, users are assumed to be perfectly rational in minimizing their own travel costs or perceived travel costs. However, users may not be perfectly rational in implementing their choices in reality. There exists a kind of boundedly rational users, that is, oblivious users. These oblivious users make their route choices by simple criteria, for example, selecting the shortest (or the most direct route only based on physical distance or simply following routes recommended by a GPS system. This paper investigates how the existence of oblivious users affects the equilibrium bus line choice behavior in a public transit system. And we propose a method to design a more realistic system.

Choice of Professional and Educational Route in High School Students with Disabilities: University Education in the Context of Motivation and Needs

Directory of Open Access Journals (Sweden)

Kantor V.Z.

2018-05-01

Full Text Available The article presents the results of a questionnaire survey in the context of the idea of continuity of school and university education of persons with disabilities. 90 senior students with visual, hearing and motor impairments were the respondents of the survey. The purpose of the survey was to study the motives, preferences and needs of school graduates among disabled people, which determine the choice of their vocational and educational route. The survey reveals features of motivation for professional choice of various categories of enrollees with disabilities and its informational support; assesses the level of these enrollees needs in helping by career counselors; identifies the preferred forms of higher education by persons with disabilities; characterizes the needs of people with disabilities in special equipment and services in obtaining higher education, as well as in adaptation of educational programs in the university. The resulting practical-oriented conclusions concern both purpose and content of the work with disabled enrollees from among school graduates as well as approaches to the organization of higher education for persons with disabilities.

Age ratios and their possible use in determining autumn routes of passerine migrants

Science.gov (United States)

C. John Ralph

1981-01-01

Age ratios and abundance of 61 migrant passerine species comprising more than 42,000 birds were analyzed in an attempt to determine patterns of migration. The data were collected at 10 stations from coastal Massachusetts to inland Pennsylvania. Age ratios are thought to be useful in determining routes of migration. The principal criteria for the edge of a species...

Routes of human trafficking in Europe and the position of Serbia on them

Directory of Open Access Journals (Sweden)

Ćopić Sanja

2008-01-01

Full Text Available Human trafficking as a form of organized crime is showing its increase today, changing at the same time its structure and characteristics. Some factors that contribute to such a situation are global trends that result in huge social and economic inequalities in the world, but also turbulences and problems that are affecting certain regions (wars, political instability, ethnic conflicts, militarization etc.. Human trafficking, as a complex social phenomenon that encompasses different forms of acting, subjects and aims, can be analyzed within different concepts. One of them refers to the issue of broader migration flows and migration control policy. Namely, from the global perspective, trafficking in human beings can be mostly considered as a form of 'organized illegal migration'. Due to that, it seems important to consider the issue of routes through which this form of migration is realized today. Discovering human trafficking routes, as well as other forms of illegal movement of people and illegal forms of trade are very important from the point of view of implementing adequate measures and relocation of resources in order to suppress these forms of socially unacceptable phenomena. Creating adequate anti-trafficking activities is important on national, regional and international levels. Keeping that in mind, the aim of this paper is to look into the contemporary routes of human trafficking within Europe and find out what is the position of Serbia on these routes, as well to examine possible changes that happened in this field during past several years. This will be done on the basis of the analysis of relevant literature, as well as on some preliminary findings of the survey on male victims of human trafficking in Serbia, which is currently conducted by the Victimology Society of Serbia.

Out of Africa: the importance of rivers as human migration corridors

Science.gov (United States)

Ramirez, J. A.; Coulthard, T. J.; Rogerson, M.; Barton, N.; Bruecher, T.

2013-12-01

The route and timing of Homo sapiens exiting Africa remains uncertain. Corridors leading out of Africa through the Sahara, the Nile Valley, and the Red Sea coast have been proposed as migration routes for anatomically modern humans 80,000-130,000 years ago. During this time climate conditions in the Sahara were wetter than present day, and monsoon rainfall fed rivers that flowed across the desert landscape. The location and timing of these rivers may have supported human migration northward from central Africa to the Mediterranean coast, and onwards to Europe or Asia. Here, we use palaeoclimate rainfall and a hydrological model to spatially simulate and quantitatively test the existence of three major rivers crossing the Sahara from south to north during the time of human migration. We provide evidence that, given realistic underlying climatology, the well-known Sahabi and Kufrah rivers very likely flowed across modern day Libya and reached the coast. More unexpectedly an additional river crossed the core of the Sahara through Algeria (Irharhar river) and flowed into the Chotts basin. The Irharhar river is unique, because it links locations in central Africa experiencing monsoon climates with temperate coastal Mediterranean environments where food and resources were likely abundant. From an ecological perspective, this little-known corridor may prove to be the most parsimonious migration route. Support for the Irharar as a viable migration corridor is provided by its geographic proximity to middle Stone Age archaeological artefacts found in North Africa. Our new, highly novel approach provides the first quantitative analysis of the likelihood that rivers occurred during the critical period of human migration out of Africa. Simulated probability of surface water in North Africa during the last interglacial and the location of tools and ornaments from the Middle Stone Age.

Behavioral lateralization and optimal route choice in flying budgerigars.

OpenAIRE

Partha S Bhagavatula; Charles Claudianos; Michael R Ibbotson; Mandyam V Srinivasan

2014-01-01

Birds flying through a cluttered environment require the ability to choose routes that will take them through the environment safely and quickly. We have investigated some of the strategies by which they achieve this. We trained budgerigars to fly through a tunnel in which they encountered a barrier that offered two passages, positioned side by side, at the halfway point. When one of the passages was substantially wider than the other, the birds tended to fly through the wider passage to cont...

Indonesia's migration transition.

Science.gov (United States)

Hugo, G

1995-01-01

This article describes population movements in Indonesia in the context of rapid and marked social and economic change. Foreign investment in Indonesia is increasing, and global mass media is available to many households. Agriculture is being commercialized, and structural shifts are occurring in the economy. Educational levels are increasing, and women's role and status are shifting. Population migration has increased over the decades, both short and long distance, permanent and temporary, legal and illegal, and migration to and between urban areas. This article focuses specifically on rural-to-urban migration and international migration. Population settlements are dense in the agriculturally rich inner areas of Java, Bali, and Madura. Although the rate of growth of the gross domestic product was 6.8% annually during 1969-94, the World Bank ranked Indonesia as a low-income economy in 1992 because of the large population size. Income per capita is US $670. Indonesia is becoming a large exporter of labor to the Middle East, particularly women. The predominance of women as overseas contract workers is changing women's role and status in the family and is controversial due to the cases of mistreatment. Malaysia's high economic growth rate of over 8% per year means an additional 1.3 million foreign workers and technicians are needed. During the 1980s urban growth increased at a very rapid rate. Urban growth tended to occur along corridors and major transportation routes around urban areas. It is posited that most of the urban growth is due to rural-to-urban migration. Data limitations prevent an exact determination of the extent of rural-to-urban migration. More women are estimated to be involved in movements to cities during the 1980s compared to the 1970s. Recruiters and middlemen have played an important role in rural-to-urban migration and international migration.

Materials Processing Routes to Trap-Free Halide Perovskites

KAUST Repository

Buin, Andrei; Pietsch, Patrick; Xu, Jixian; Voznyy, Oleksandr; Ip, Alexander H.; Comin, Riccardo; Sargent, Edward H.

2014-01-01

that the specific choice of growth conditions and chemical precursors is central to achieving superior performance from these materials; yet the roles and mechanisms underlying the selection of materials processing route is poorly understood. Here we show that films

Tour Route Multiobjective Optimization Design Based on the Tourist Satisfaction

Directory of Open Access Journals (Sweden)

Yan Han

2014-01-01

Full Text Available The question prompted is how to design the tour route to make the tourists get the maximum satisfactions considering the tourists’ demand. The influence factors of the tour route choices of tourists were analyzed and tourists’ behavior characteristics and psychological preferences were regarded as the important influence factors based on the tourist behavioral theories. A questionnaire of tourists’ tour route information and satisfaction degree was carried out. Some information about the scene spot and tourists demand and tour behaviors characteristic such as visit frequency, number of attractions visited was obtained and analyzed. Based on the convey datum, tour routes multiobjective optimization functions were prompted for the tour route design regarding the maximum satisfaction and the minimum tour distance as the optimal objective. The available routes are listed and categorized. Based on the particle swarm optimization model, the priorities of the tour route are calculated and finally the suggestion depth tour route and quick route tour routes are given considering the different tour demands of tourists. The results can offer constructive suggestions on how to design tour routes on the part of tourism enterprises and how to choose a proper tour route on the part of tourists.

Cyclist route choice, traffic-related air pollution, and lung function: a scripted exposure study.

Science.gov (United States)

Jarjour, Sarah; Jerrett, Michael; Westerdahl, Dane; de Nazelle, Audrey; Hanning, Cooper; Daly, Laura; Lipsitt, Jonah; Balmes, John

2013-02-07

A travel mode shift to active transportation such as bicycling would help reduce traffic volume and related air pollution emissions as well as promote increased physical activity level. Cyclists, however, are at risk for exposure to vehicle-related air pollutants due to their proximity to vehicle traffic and elevated respiratory rates. To promote safe bicycle commuting, the City of Berkeley, California, has designated a network of residential streets as "Bicycle Boulevards." We hypothesized that cyclist exposure to air pollution would be lower on these Bicycle Boulevards when compared to busier roads and this elevated exposure may result in reduced lung function. We recruited 15 healthy adults to cycle on two routes - a low-traffic Bicycle Boulevard route and a high-traffic route. Each participant cycled on the low-traffic route once and the high-traffic route once. We mounted pollutant monitors and a global positioning system (GPS) on the bicycles. The monitors were all synced to GPS time so pollutant measurements could be spatially plotted. We measured lung function using spirometry before and after each bike ride. We found that fine and ultrafine particulate matter, carbon monoxide, and black carbon were all elevated on the high-traffic route compared to the low-traffic route. There were no corresponding changes in the lung function of healthy non-asthmatic study subjects. We also found that wind-speed affected pollution concentrations. These results suggest that by selecting low-traffic Bicycle Boulevards instead of heavily trafficked roads, cyclists can reduce their exposure to vehicle-related air pollution. The lung function results indicate that elevated pollutant exposure may not have acute negative effects on healthy cyclists, but further research is necessary to determine long-term effects on a more diverse population. This study and broader field of research have the potential to encourage policy-makers and city planners to expand infrastructure to

Satellite tracking of two Montagu's Harriers (Circus pygargus) : Dual pathways during autumn migration

NARCIS (Netherlands)

Trierweiler, Christiane; Koks, Ben J.; Drent, Rudi H.; Exo, Klaus-Michael; Komdeur, Jan; Dijkstra, Cor; Bairlein, Franz

2007-01-01

Autumn migration routes of two Dutch female Montagu's Harriers (Circus pygargus) were documented for the first time using satellite telemetry. Both migrated to their African wintering area-one via the Straits of Gibraltar through the Mediterranean and the other via Italy/Tunisia. The rate of travel

An Improved 6LoWPAN Hierarchical Routing Protocol

Directory of Open Access Journals (Sweden)

Xue Li

2015-10-01

Full Text Available IETF 6LoWPAN working group is engaged in the IPv6 protocol stack research work based on IEEE802.15.4 standard. In this working group, the routing protocol is one of the important research contents. In the 6LoWPAN, HiLow is a well-known layered routing protocol. This paper puts forward an improved hierarchical routing protocol GHiLow by improving HiLow parent node selection and path restoration strategy. GHiLow improves the parent node selection by increasing the choice of parameters. Simutaneously, it also improves path recovery by analysing different situations to recovery path. Therefore, GHiLow contributes to the ehancement of network performance and the decrease of network energy consumption.

Heading south or north: novel insights on European silver eel Anguilla anguilla migration in the North Sea

NARCIS (Netherlands)

Huisman, Jeroen; Verhelst, Pieterjan; Verhelst, Pieterjan; Deneudt, K.; Goethals, Peter; Moens, Tom; Nagelkerke, Leopold A.J.; Nolting, Carsten; Reubens, Jan; Schollema, Peter Paul; Winter, Hendrik V.; Mouton, Ans

2016-01-01

The European eel Anguilla anguilla L. is a critically endangered fish species that migrates from coastal and freshwater habitats to the Sargasso Sea to spawn. However, the exact migration routes and destination of European eel are still unknown. We are the first to observe southward migrating

Modelling the adaptive behaviour of migrating white storks

NARCIS (Netherlands)

Shamoun-Baranes, J.; van Loon, E.E.; Bouten, W.

2006-01-01

White storks (Ciconia ciconia) are soaring migrants whose western Palearctic populations use several migration routes, concentrating mainly over Gibraltar and Israel to cross between their Palearctic breeding grounds and wintering grounds in Africa. A wealth of data has been collected during the

Geomagnetic imprinting predicts spatio-temporal variation in homing migration of pink and sockeye salmon

Science.gov (United States)

Putman, Nathan F.; Jenkins, Erica S.; Michielsens, Catherine G. J.; Noakes, David L. G.

2014-01-01

Animals navigate using a variety of sensory cues, but how each is weighted during different phases of movement (e.g. dispersal, foraging, homing) is controversial. Here, we examine the geomagnetic and olfactory imprinting hypotheses of natal homing with datasets that recorded variation in the migratory routes of sockeye (Oncorhynchus nerka) and pink (Oncorhynchus gorbuscha) salmon returning from the Pacific Ocean to the Fraser River, British Columbia. Drift of the magnetic field (i.e. geomagnetic imprinting) uniquely accounted for 23.2% and 44.0% of the variation in migration routes for sockeye and pink salmon, respectively. Ocean circulation (i.e. olfactory imprinting) predicted 6.1% and 0.1% of the variation in sockeye and pink migration routes, respectively. Sea surface temperature (a variable influencing salmon distribution but not navigation, directly) accounted for 13.0% of the variation in sockeye migration but was unrelated to pink migration. These findings suggest that geomagnetic navigation plays an important role in long-distance homing in salmon and that consideration of navigation mechanisms can aid in the management of migratory fishes by better predicting movement patterns. Finally, given the diversity of animals that use the Earth's magnetic field for navigation, geomagnetic drift may provide a unifying explanation for spatio-temporal variation in the movement patterns of many species. PMID:25056214

Analysis of genomic data as an approach to understanding migration in song birds

OpenAIRE

Boss, John

2015-01-01

Many species of birds migrate every year thousands of kilometers, relying on sight, memory, magnetic sensors and instincts to find their way across continents. Many juvenile birds travel complicated migration routes without the guidance of more experienced adults. To successfully accomplish this they need instincts that utilizes multiple navigational senses together with a time dependent schedule. Little is known of the genetics behind migration behavior and which cellular processes are invol...

Political motivations for intra-European migration.

Science.gov (United States)

Bygnes, Susanne; Flipo, Aurore

2017-08-01

Motivations for migrating within the European Union have mainly been attributed to economic, career and lifestyle choices. This article suggests that political dissatisfaction is also an important motivator of recent intra-European migration. In our analysis of in-depth interviews with Romanian migrants in Spain and with Spanish migrants in Norway, we found a common emphasis on the political dimensions of their decision to migrate. In the interviews, the economic component of migration was often related to bad governance and negative perceptions of the state. The similarities of Spanish and Romanian migration narratives are especially striking because Spain and Romania represent substantially different migratory, political and economic contexts. However, migration is more obviously intertwined with conventional acts of political protest in the Spanish case. We suggest that differences in democratic contexts are pivotal in people's reactions to and framing of their deep dissatisfaction with domestic politics, as found in many European countries today.

Simulating the Oceanic Migration of Silver Japanese Eels.

Directory of Open Access Journals (Sweden)

Yu-Lin Chang

Full Text Available The oceanic migration of silver Japanese eels starts from their continental growth habitats in East Asia and ends at the spawning area near the West Mariana Ridge seamount chain. However, the actual migration routes remain unknown. In this study, we examined the possible oceanic migration routes and strategies of silver Japanese eels using a particle tracking method in which virtual eels (v-eels were programmed to move vertically and horizontally in an ocean circulation model (Japan Coastal Ocean Predictability Experiment 2, JCOPE2. Four horizontal swimming strategies were tested: random heading, true navigation (readjusted heading, orientation toward the spawning area (fixed heading, and swimming against the Kuroshio. We found that all strategies, except random swimming, allowed v-eels swimming at 0.65 m s-1 to reach the spawning area within eight months after their departure from the south coast of Japan (end of the spawning season. The estimated minimum swimming speed required to reach the area spawning within eight months was 0.1 m s-1 for true navigation, 0.12 m s-1 for constant compass heading, and 0.35 m s-1 for swimming against the Kuroshio. The lowest swimming speed estimated from tracked Japanese eels at sea was 0.03 m.s-1, which would not allow them to reach the spawning area within eight months, through any of the tested orientation strategies. Our numerical experiments also showed that ocean circulation significantly affected the migration of Japanese v-eels. A strong Kuroshio could advect v-eels further eastward. In addition, western Pacific ocean currents accelerated the migration of navigating v-eels. The migration duration was shortened in years with a stronger southward flow, contributed by a stronger recirculation south of Japan, an enhanced subtropical gyre, or a higher southward Kuroshio velocity.

Simulating the Oceanic Migration of Silver Japanese Eels.

Science.gov (United States)

Chang, Yu-Lin; Miyazawa, Yasumasa; Béguer-Pon, Mélanie

2016-01-01

The oceanic migration of silver Japanese eels starts from their continental growth habitats in East Asia and ends at the spawning area near the West Mariana Ridge seamount chain. However, the actual migration routes remain unknown. In this study, we examined the possible oceanic migration routes and strategies of silver Japanese eels using a particle tracking method in which virtual eels (v-eels) were programmed to move vertically and horizontally in an ocean circulation model (Japan Coastal Ocean Predictability Experiment 2, JCOPE2). Four horizontal swimming strategies were tested: random heading, true navigation (readjusted heading), orientation toward the spawning area (fixed heading), and swimming against the Kuroshio. We found that all strategies, except random swimming, allowed v-eels swimming at 0.65 m s-1 to reach the spawning area within eight months after their departure from the south coast of Japan (end of the spawning season). The estimated minimum swimming speed required to reach the area spawning within eight months was 0.1 m s-1 for true navigation, 0.12 m s-1 for constant compass heading, and 0.35 m s-1 for swimming against the Kuroshio. The lowest swimming speed estimated from tracked Japanese eels at sea was 0.03 m.s-1, which would not allow them to reach the spawning area within eight months, through any of the tested orientation strategies. Our numerical experiments also showed that ocean circulation significantly affected the migration of Japanese v-eels. A strong Kuroshio could advect v-eels further eastward. In addition, western Pacific ocean currents accelerated the migration of navigating v-eels. The migration duration was shortened in years with a stronger southward flow, contributed by a stronger recirculation south of Japan, an enhanced subtropical gyre, or a higher southward Kuroshio velocity.

Geomagnetic imprinting predicts spatio-temporal variation in homing migration of pink and sockeye salmon.

Science.gov (United States)

Putman, Nathan F; Jenkins, Erica S; Michielsens, Catherine G J; Noakes, David L G

2014-10-06

Animals navigate using a variety of sensory cues, but how each is weighted during different phases of movement (e.g. dispersal, foraging, homing) is controversial. Here, we examine the geomagnetic and olfactory imprinting hypotheses of natal homing with datasets that recorded variation in the migratory routes of sockeye (Oncorhynchus nerka) and pink (Oncorhynchus gorbuscha) salmon returning from the Pacific Ocean to the Fraser River, British Columbia. Drift of the magnetic field (i.e. geomagnetic imprinting) uniquely accounted for 23.2% and 44.0% of the variation in migration routes for sockeye and pink salmon, respectively. Ocean circulation (i.e. olfactory imprinting) predicted 6.1% and 0.1% of the variation in sockeye and pink migration routes, respectively. Sea surface temperature (a variable influencing salmon distribution but not navigation, directly) accounted for 13.0% of the variation in sockeye migration but was unrelated to pink migration. These findings suggest that geomagnetic navigation plays an important role in long-distance homing in salmon and that consideration of navigation mechanisms can aid in the management of migratory fishes by better predicting movement patterns. Finally, given the diversity of animals that use the Earth's magnetic field for navigation, geomagnetic drift may provide a unifying explanation for spatio-temporal variation in the movement patterns of many species. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

A pilgrim's progress: Seeking meaning in primordial germ cell migration.

Science.gov (United States)

Cantú, Andrea V; Laird, Diana J

2017-10-01

Comparative studies of primordial germ cell (PGC) development across organisms in many phyla reveal surprising diversity in the route of migration, timing and underlying molecular mechanisms, suggesting that the process of migration itself is conserved. However, beyond the perfunctory transport of cellular precursors to their later arising home of the gonads, does PGC migration serve a function? Here we propose that the process of migration plays an additional role in quality control, by eliminating PGCs incapable of completing migration as well as through mechanisms that favor PGCs capable of responding appropriately to migration cues. Focusing on PGCs in mice, we explore evidence for a selective capacity of migration, considering the tandem regulation of proliferation and migration, cell-intrinsic and extrinsic control, the potential for tumors derived from failed PGC migrants, the potential mechanisms by which migratory PGCs vary in their cellular behaviors, and corresponding effects on development. We discuss the implications of a selective role of PGC migration for in vitro gametogenesis. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Geography, Islands and Migration in an Era of Global Mobility

Directory of Open Access Journals (Sweden)

Russell King

2009-05-01

Full Text Available This paper examines the changing role of islands in the age of globalization and in an era of enhanced and diversified mobility. There are many types of islands, many metaphors of insularity, and many types of migration, so the interactions are far from simple. The ‘mobilities turn’ in migration studies recognizes the diversification in motivations and time-space regimes of human migration. After brief reviews of island studies and of migration studies, and the power of geography to capture and distil the interdisciplinarity and relationality of these two study domains, the paper explores various facets of the generally intense engagement that islands have with migration. Two particular scenarios are identified for islands and migration in the global era: the heuristic role of islands as ‘spatial laboratories’ for the study of diverse migration processes in microcosm; and the way in which, especially in the Mediterranean and near-Atlantic regions, islands have become critical locations in the geopolitics of irregular migration routes. The case of Malta is taken to illustrate some of these new insular migration dynamics.

Satellite tracking of the migration of Whooper Swans Cygnus cygnus wintering in Japan

Science.gov (United States)

Shimada, Tetsuo; Yamaguchi, Noriyuki M.; Hijikata, N.; Hiraoka, Emiko N.; Hupp, Jerry; Flint, Paul L.; Tokita, Ken-ichi; Fujita, Go; Uchida, Kiyoshi; Sato, F.; Kurechi, Masayuki; Pearce, John M.; Ramey, Andy M.; Higuchi, Hiroyoshi

2014-01-01

We satellite-tracked Whooper Swans Cygnus cygnus wintering in northern Japan to document their migration routes and timing, and to identify breeding areas. From 47 swans that we marked at Lake Izunuma-Uchinuma, Miyagi Prefecture, northeast Honshu, and at Lake Kussharo, east Hokkaido, we observed 57 spring and 33 autumn migrations from 2009-2012. In spring, swans migrated north along Sakhalin Island from eastern Hokkaido using stopovers in Sakhalin, at the mouth of the Amur River and in northern coastal areas of the Sea of Okhotsk. They ultimately reached molting/breedmg areas along the Indigirka River and the lower Kolyma River in northern Russia. In autumn, the swans basically reversed the spring migration routes. We identified northern Honshu, eastern Hokkaido, coastal areas in Sakhalin, the lower Amur River and northern coastal areas of the Sea of Okhotsk as the most frequent stopover sites, and the middle reaches of the Indigirka and the lower Kolyma River as presumed breeding sites. Our results are helpful in understanding the distribution of the breeding and stopover sites of Whooper Swans wintering in Japan and in identifying their major migration habitats. Our findings contribute to understanding the potential transmission process of avian influenza viruses potentially carried by swans, and provide information necessary to conserve Whooper Swans in East Asia.

Can a foreign body migrate against natural body barriers?

African Journals Online (AJOL)

Amr A. Arafat, Abdel-Hady M. Taha, Ahmed G. Elkhouly and Abdelmotagaly A. Elgalad. Pericardial foreign bodies (FBs) are a rare cause of chest pain in children. They can reach the pericardium through several routes including direct or iatrogenic implantation, transbronchial or transesophageal migration of inhaled or.

Energy Reserves, Information Need and a Pinch of Personality Determine Decision-Making on Route in Partially Migratory Blue Tits.

Directory of Open Access Journals (Sweden)

Anna L K Nilsson

Full Text Available In facultative partial migrants some individuals in a population are migratory and others are resident and individuals decide each year anew which strategy to choose. While the proportion of birds migrating is in part determined by environmental conditions and competitive abilities, the timing of individual departure and behaviours on route are little understood. Individuals encounter different environmental conditions when migrating earlier or later. Based on cost/ benefit considerations we tested whether behaviours on route were affected by time constraints, personality and/or age in a partially migrating population of Blue tits (Cyanistes caeruleus. We captured female Blue tits on migration at the Southern tip of Sweden during early, peak and late migration and measured latency to feed in an unfamiliar environment, exploration of a novel object and hesitation to feed beside a novel object (neophobia. Lean birds and birds with long wings started feeding earlier when released into the cage indicating that foraging decisions were mainly determined by energetic needs (lean and large birds. However, juveniles commenced feeding later with progression of the migratory season in concordance with predictions about personality effects. Furthermore, lean birds started to explore earlier than birds with larger fat reserves again indicating an effect of maintaining threshold energy reserves. Moreover, late migrating juveniles, started to explore earlier than early migrating juveniles possibly due to time constraints to find high-quality foraging patches or a suitable winter home. Finally, neophobia did not change over the migratory season indicating that this behaviour is not compromised by time constraints. The results overall indicate that decisions on route are mainly governed by energetic requirements and current needs to learn about the environment and only to a small extent by differences in personality.

Energy Reserves, Information Need and a Pinch of Personality Determine Decision-Making on Route in Partially Migratory Blue Tits.

Science.gov (United States)

Nilsson, Anna L K; Nilsson, Jan-Åke; Mettke-Hofmann, Claudia

2016-01-01

In facultative partial migrants some individuals in a population are migratory and others are resident and individuals decide each year anew which strategy to choose. While the proportion of birds migrating is in part determined by environmental conditions and competitive abilities, the timing of individual departure and behaviours on route are little understood. Individuals encounter different environmental conditions when migrating earlier or later. Based on cost/ benefit considerations we tested whether behaviours on route were affected by time constraints, personality and/or age in a partially migrating population of Blue tits (Cyanistes caeruleus). We captured female Blue tits on migration at the Southern tip of Sweden during early, peak and late migration and measured latency to feed in an unfamiliar environment, exploration of a novel object and hesitation to feed beside a novel object (neophobia). Lean birds and birds with long wings started feeding earlier when released into the cage indicating that foraging decisions were mainly determined by energetic needs (lean and large birds). However, juveniles commenced feeding later with progression of the migratory season in concordance with predictions about personality effects. Furthermore, lean birds started to explore earlier than birds with larger fat reserves again indicating an effect of maintaining threshold energy reserves. Moreover, late migrating juveniles, started to explore earlier than early migrating juveniles possibly due to time constraints to find high-quality foraging patches or a suitable winter home. Finally, neophobia did not change over the migratory season indicating that this behaviour is not compromised by time constraints. The results overall indicate that decisions on route are mainly governed by energetic requirements and current needs to learn about the environment and only to a small extent by differences in personality.

Effect of simplicity and attractiveness on route selection for different journey types

OpenAIRE

Cook, S; Ruddle, RA

2014-01-01

This study investigated the effects of six attributes, associated with simplicity or attractiveness, on route preference for three pedestrian journey types (everyday, leisure and tourist). Using stated choice preference experiments with computer generated scenes, participants were asked to choose one of a pair of routes showing either two levels of the same attribute (experiment 1) or different attributes (experiment 2). Contrary to predictions, vegetation was the most influential for both ev...

"Choice of Air Cargo Transshipment Airport: An Application to Air Cargo Traffic to/from Northeast Asia"

OpenAIRE

Hiroshi Ohashi; Tae-Seung Kim; Tae Hoon Oum; Chunyan Yu

2004-01-01

Based on a unique data set of 760 air cargo transshipment routings to/from the Northeast Asian region in 2000, this paper applies an aggregate form of multinomial logit model to identify the critical factors influencing air cargo transshipment route choice decisions. The analysis focuses on the trade-off between monetary cost and time cost while considering other variables relevant for choice of transshipment airport. The estimation method considers the presence of unobserved attributes, and ...

Choosing the safest route: frog orientation in an agricultural landscape

NARCIS (Netherlands)

Mazerolle, M.J.; Vos, C.C.

2006-01-01

Orientation is a key component to successful movements between habitats. We hypothesized that barren agricultural landscapes hinder the ability of frogs to orient and move between habitats. Specifically, we predicted that when presented with a choice between a short route through a hostile

Hemispheric-scale wind selection facilitates bar-tailed godwit circum-migration of the Pacific

Science.gov (United States)

Gill, Robert E.; Douglas, David C.; Handel, Colleen M.; Tibbitts, T. Lee; Hufford, Gary; Piersma, Theunis

2014-01-01

The annual 29 000 km long migration of the bar-tailed godwit, Limosa lapponica baueri, around the Pacific Ocean traverses what is arguably the most complex and seasonally structured atmospheric setting on Earth. Faced with marked variation in wind regimes and storm conditions across oceanic migration corridors, individuals must make critical decisions about when and where to fly during nonstop flights of a week's duration or longer. At a minimum, their decisions will affect wind profitability and thus reduce energetic costs of migration; in the extreme, poor decisions or unpredictable weather events will risk survival. We used satellite telemetry to track the annual migration of 24 bar-tailed godwits and analysed their flight performance relative to wind conditions during three major migration legs between nonbreeding grounds in New Zealand and breeding grounds in Alaska. Because flight altitudes of birds en route were unknown, we modelled flight efficiency at six geopotential heights across each migratory segment. Birds selected departure dates when atmospheric conditions conferred the greatest wind assistance both at departure and throughout their flights. This behaviour suggests that there exists a cognitive mechanism, heretofore unknown among migratory birds, that allows godwits to assess changes in weather conditions that are linked (i.e. teleconnected) across widely separated atmospheric regions. Godwits also showed adaptive flexibility in their response not only to cues related to seasonal changes in macrometeorology, such as spatial shifting of storm tracks and temporal periods of cyclogenesis, but also to cues associated with stochastic events, especially at departure sites. Godwits showed limits to their response behaviours, however, especially relative to rapidly developing stochastic events while en route. We found that flight efficiency depended significantly upon altitude and hypothesize that godwits exhibit further adaptive flexibility by varying

Plasmodium spp. in raptors on the Eurasian-African migration route.

Science.gov (United States)

Paperna, I; Yosef, R; Landau, I

2007-12-01

Examination of blood smears obtained from raptors trapped while on migration at Eilat, Israel, demonstrated Plasmodium infection in Accipiter brevipes and Buteo buteo. The following species are described, from A. brevipes: Plasmodium alloelongatum n. sp., P. accipiteris n. sp. and from B. buteo: P. buteonis n. sp. and Plasmodium sp. for which we lack sufficient data for adequate species description. Overall prevalence of infection with Plasmodium spp. was very low: among 38 examined A. brevipes 5% and among 56 B. buteo 3.6%.

Narrow-front loop migration in a population of the common cuckoo Cuculus canorus, as revealed by satellite telemetry

NARCIS (Netherlands)

Willemoes, Mikkel; Strandberg, Roine; Klaassen, Raymond H. G.; Tottrup, Anders P.; Vardanis, Yannis; Howey, Paul W.; Thorup, Kasper; Wikelski, Martin; Alerstam, Thomas

2014-01-01

Narrow migration corridors known in diurnal, social migrants such as raptors, storks and geese are thought to be caused by topographical leading line effects in combination with learning detailed routes across generations. Here, we document narrow-front migration in a nocturnal, solitary migrant,

International Student Migration: Outcomes and Implications

Science.gov (United States)

McGill, Jenny

2013-01-01

The present study examined the possible correlation between six life circumstances of international students (N = 124) admitted entry into the United States for the purpose of academic study and their geographic choice of location upon graduation. This paper improves upon the current literature by offering actual migration outcomes (rather than…

Planning Routes Across Economic Terrains: Maximizing Utility, Following Heuristics

Science.gov (United States)

Zhang, Hang; Maddula, Soumya V.; Maloney, Laurence T.

2010-01-01

We designed an economic task to investigate human planning of routes in landscapes where travel in different kinds of terrain incurs different costs. Participants moved their finger across a touch screen from a starting point to a destination. The screen was divided into distinct kinds of terrain and travel within each kind of terrain imposed a cost proportional to distance traveled. We varied costs and spatial configurations of terrains and participants received fixed bonuses minus the total cost of the routes they chose. We first compared performance to a model maximizing gain. All but one of 12 participants failed to adopt least-cost routes and their failure to do so reduced their winnings by about 30% (median value). We tested in detail whether participants’ choices of routes satisfied three necessary conditions (heuristics) for a route to maximize gain. We report failures of one heuristic for 7 out of 12 participants. Last of all, we modeled human performance with the assumption that participants assign subjective utilities to costs and maximize utility. For 7 out 12 participants, the fitted utility function was an accelerating power function of actual cost and for the remaining 5, a decelerating power function. We discuss connections between utility aggregation in route planning and decision under risk. Our task could be adapted to investigate human strategy and optimality of route planning in full-scale landscapes. PMID:21833269

PLANNING ROUTES ACROSS ECONOMIC TERRAINS: MAXIMIZING UTILITY, FOLLOWING HEURISTICS

Directory of Open Access Journals (Sweden)

Hang eZhang

2010-12-01

Full Text Available We designed an economic task to investigate human planning of routes in landscapes where travel in different kinds of terrain incurs different costs. Participants moved their finger across a touch screen from a starting point to a destination. The screen was divided into distinct kinds of terrain and travel within each kind of terrain imposed a cost proportional to distance traveled. We varied costs and spatial configurations of terrains and participants received fixed bonuses minus the total cost of the routes they chose. We first compared performance to a model maximizing gain. All but one of 12 participants failed to adopt least-cost routes and their failure to do so reduced their winnings by about 30% (median value. We tested in detail whether participants’ choices of routes satisfied three necessary conditions (heuristics for a route to maximize gain. We report failures of one heuristic for 7 out of 12 participants. Last of all, we modeled human performance with the assumption that participants assign subjective utilities to costs and maximize utility. For 7 out 12 participants, the fitted utility function was an accelerating power function of actual cost and for the remaining 5, a decelerating power function. We discuss connections between utility aggregation in route planning and decision under risk. Our task could be adapted to investigate human strategy and optimality of route planning in full-scale landscapes.

A Subpath-based Logit Model to Capture the Correlation of Routes

Directory of Open Access Journals (Sweden)

Xinjun Lai

2016-06-01

Full Text Available A subpath-based methodology is proposed to capture the travellers’ route choice behaviours and their perceptual correlation of routes, because the original link-based style may not be suitable in application: (1 travellers do not process road network information and construct the chosen route by a link-by-link style; (2 observations from questionnaires and GPS data, however, are not always link-specific. Subpaths are defined as important portions of the route, such as major roads and landmarks. The cross-nested Logit (CNL structure is used for its tractable closed-form and its capability to explicitly capture the routes correlation. Nests represent subpaths other than links so that the number of nests is significantly reduced. Moreover, the proposed method simplifies the original link-based CNL model; therefore, it alleviates the estimation and computation difficulties. The estimation and forecast validation with real data are presented, and the results suggest that the new method is practical.

A Monarch Butterfly Optimization for the Dynamic Vehicle Routing Problem

Directory of Open Access Journals (Sweden)

Shifeng Chen

2017-09-01

Full Text Available The dynamic vehicle routing problem (DVRP is a variant of the Vehicle Routing Problem (VRP in which customers appear dynamically. The objective is to determine a set of routes that minimizes the total travel distance. In this paper, we propose a monarch butterfly optimization (MBO algorithm to solve DVRPs, utilizing a greedy strategy. Both migration operation and the butterfly adjusting operator only accept the offspring of butterfly individuals that have better fitness than their parents. To improve performance, a later perturbation procedure is implemented, to maintain a balance between global diversification and local intensification. The computational results indicate that the proposed technique outperforms the existing approaches in the literature for average performance by at least 9.38%. In addition, 12 new best solutions were found. This shows that this proposed technique consistently produces high-quality solutions and outperforms other published heuristics for the DVRP.

Distribution and Joint Fish-Tag Survival of Juvenile Chinook Salmon Migrating through the Sacramento-San Joaquin River Delta, California, 2008

Science.gov (United States)

Holbrook, Christopher M.; Perry, Russell W.; Adams, Noah S.

2009-01-01

Acoustic telemetry was used to obtain the movement histories of 915 juvenile fall-run Chinook salmon (Oncorhynchus tshawytscha) through the lower San Joaquin River and Sacramento-San Joaquin Delta, California, in 2008. Data were analyzed within a release-recapture framework to estimate survival, route distribution, and detection probabilities among three migration pathways through the Delta. The pathways included the primary route through the San Joaquin River and two less direct routes (Old River and Turner Cut). Strong inferences about survival were limited by premature tag failure, but estimates of fish distribution among migration routes should be unaffected by tag failure. Based on tag failure tests (N = 66 tags), we estimated that only 55-78 percent of the tags used in this study were still functioning when the last fish was detected exiting the study area 15 days after release. Due to premature tag failure, our 'survival' estimates represent the joint probability that both the tag and fish survived, not just survival of fish. Low estimates of fish-tag survival could have been caused by fish mortality or fish travel times that exceeded the life of the tag, but we were unable to differentiate between the two. Fish-tag survival through the Delta (from Durham Ferry to Chipps Island by all routes) ranged from 0.05 +or- 0.01 (SE) to 0.06 +or- 0.01 between the two weekly release groups. Among the three migration routes, fish that remained in the San Joaquin River exhibited the highest joint fish-tag survival (0.09 +or- 0.02) in both weeks, but only 22-33 percent of tagged fish used this route, depending on the week of release. Only 4-10 percent (depending on week) of tagged fish traveled through Turner Cut, but no tagged fish that used this route were detected exiting the Delta. Most fish (63-68 percent, depending on week of release) migrated through Old River, but fish-tag survival through this route (0.05 +or- 0.01) was only about one-half that of fish that

Esophageal stent migration can lead to intestinal obstruction

Science.gov (United States)

Karatepe, Oguzhan; Acet, Ersin; Altiok, Merih; Battal, Muharrem; Adas, Gokhan; Karahan, Servet

2009-01-01

Background: Self-expanding metallic stents are the devices of choice in the treatment of malign or benign strictures of the esophagus. Stent migration is a well-known complication of this procedure. Aims: We report a case of intestinal obstruction caused by esophageal stent migration, in which surgical intervention was used. Methods: A 65-year-old woman, who had a medical history of gastric cancer operations and esophageal stent applications, was admitted to our emergency department with a 48-hour history of abdominal pain, nausea and vomiting. An emergency laparotomy was performed and the migrated stent causing intestinal obstruction was removed. Results: The patient recovered without incident and was discharged on postoperative day 3. Conclusion: This case illustrates that esophageal stent migration has to be considered as a potential life-threatening complication. PMID:22666672

Turning to Teaching: Gender and Career Choice

Science.gov (United States)

Raggl, Andrea; Troman, Geoff

2008-01-01

As the largest public sector institution in the United Kingdom, education is a key site for studying the context of "choice" and changes in the identities of professional workers in contemporary society. Recruitment and retention problems in education have led to the creation of new routes into teaching to attract career changers from…

Subgenotype A1 of HBV--tracing human migrations in and out of Africa.

Science.gov (United States)

Kramvis, Anna; Paraskevis, Dimitrios

2013-01-01

HBV subgenotype A1 is the dominant genotype A strain in Africa, with molecular characteristics differentiating it from A2, which prevails elsewhere. Outside Africa, A1 is confined to areas with migration history from Africa, including India and Latin America. The aim of this study was to reconstruct A1 phylogeny on a spatial scale in order to determine whether A1 can be used to track human migrations. A phylogenetic comparison of A1 was established using neighbour-joining analysis of complete genomes, and the Bayesian method, implemented in BEAST, was performed on the S region of isolates from 22 countries. Migration events were estimated by ancestral state reconstruction using the criterion of parsimony. From the tree reconstruction, nucleotide divergence calculations and migration analysis, it was evident that Africa was the source of dispersal of A1 globally, and its dispersal to Asia and Latin America occurred at a similar time period. Strains from South Africa were the most divergent, clustering in both the African and Asian/American clades and a South African subclade was the origin of A1. The effect of the 9th to 19th century trade and slave routes on the dispersal of A1 was evident and certain unexpected findings, such as the co-clustering of Somalian and Latin American strains, and the dispersal of A1 from India to Haiti, correlated with historical evidence. Phylogeographic analyses of subgenotype A1 can be used to trace human migrations in and out of Africa and the plausible sites of origin and migration routes are presented.

Depth migration and de-migration for 3-D migration velocity analysis; Migration profondeur et demigration pour l'analyse de vitesse de migration 3D

Energy Technology Data Exchange (ETDEWEB)

Assouline, F.

2001-07-01

3-D seismic imaging of complex geologic structures requires the use of pre-stack imaging techniques, the post-stack ones being unsuitable in that case. Indeed, pre-stack depth migration is a technique which allows to image accurately complex structures provided that we have at our disposal a subsurface velocity model accurate enough. The determination of this velocity model is thus a key element for seismic imaging, and to this end, migration velocity analysis methods have met considerable interest. The SMART method is a specific migration velocity analysis method: the singularity of this method is that it does not rely on any restrictive assumptions on the complexity of the velocity model to determine. The SMART method uses a detour through the pre-stack depth migrated domain for extracting multi-offset kinematic information hardly accessible in the time domain. Once achieved the interpretation of the pre-stack depth migrated seismic data, a kinematic de-migration technique of the interpreted events enables to obtain a consistent kinematic database (i.e. reflection travel-times). Then, the inversion of these travel-times, by means of reflection tomography, allows the determination of an accurate velocity model. To be able to really image geologic structures for which the 3-D feature is predominant, we have studied the implementation of migration velocity analysis in 3-D in the context of the SMART method, and more generally, we have developed techniques allowing to overcome the intrinsic difficulties in the 3-D aspects of seismic imaging. Indeed, although formally the SMART method can be directly applied to the case of 3-D complex structures, the feasibility of its implementation requires to choose well the imaging domain. Once this choice done, it is also necessary to conceive a method allowing, via the associated de-migration, to obtain the reflection travel-times. We first consider the offset domain which constitutes, still today, the strategy most usually used

Migration: a concept analysis from a nursing perspective.

Science.gov (United States)

Freeman, Michelle; Baumann, Andrea; Blythe, Jennifer; Fisher, Anita; Akhtar-Danesh, Noori

2012-05-01

  This article is a report of a concept analysis of nurse migration.   International migration is increasing and nurse migrants are active participants in this movement. Migration is a complex term and can be examined from a range of perspectives. Analysis of nurse migration is needed to guide policy, practice and research.   A literature search was undertaken using electronic literature indexes, specific journals and websites, internet search engines and hand searches. No timeframe was placed on the search. Most literature found was published between 2001 and 2009. A sample of 80 documents met the inclusion criteria.   Walker and Avant's approach guided the analysis.   Nurse migration can be defined by five attributes: the motivation and decisions of individuals; external barriers and facilitators; freedom of choice to migrate; freedom to migrate as a human right, and dynamic movement. Antecedents of migration include the political, social, economic, legal, historical and educational forces that comprise the push and pull framework. The consequences of migration are positive or negative depending on the viewpoint and its affect on the individual and other stakeholders such as the source country, destination country, healthcare systems and the nursing profession.   This concept analysis clarified the complexities surrounding nurse migration. A nursing-specific middle-range theory was proposed to guide the understanding and study of nurse migration. © 2011 Blackwell Publishing Ltd.

Can a foreign body migrate against natural body barriers? | Arafat ...

African Journals Online (AJOL)

Pericardial foreign bodies (FBs) are a rare cause of chest pain in children. They can reach the pericardium through several routes including direct or iatrogenic implantation, transbronchial or transesophageal migration of inhaled or swallowed FBs. We reported a case of a 4-year-old girl presenting with persistent chest pain ...

Comments in reply: new directions in migration research.

Science.gov (United States)

Shaw, R P

1986-01-01

The author comments on a review of his recent book NEW DIRECTIONS IN MIGRATION RESEARCH and reflects on theory and model specification, problems of estimation and statistical inference, realities of temporal and spatial heterogeneity, choices of explanatory variables, and the importance of broader political issues in migration studies. A core hypothesis is that market forces have declined as influences on internal migration in Canada over the last 30 years. Theoretical underpinnings include declining relevance of wage considerations in the decision to migrate on the assumption that marginal utility of money diminishes and marginal utility of leisure increases as society becomes wealthier. The author perceives the human capital model to have limitations and is especially troubled by the "as if" clause--that all migrants behave "as if" they calculate benefits and risks with equal rigor. The author has "shadowed" and not quantified the costs involved. He implies that normative frameworks for future migration research and planning should be established.

Spatio-temporal migration patterns of Pacific salmon smolts in rivers and coastal marine waters.

Directory of Open Access Journals (Sweden)

Michael C Melnychuk

Full Text Available BACKGROUND: Migrations allow animals to find food resources, rearing habitats, or mates, but often impose considerable predation risk. Several behavioural strategies may reduce this risk, including faster travel speed and taking routes with shorter total distance. Descriptions of the natural range of variation in migration strategies among individuals and populations is necessary before the ecological consequences of such variation can be established. METHODOLOGY/PRINCIPAL FINDINGS: Movements of tagged juvenile coho, steelhead, sockeye, and Chinook salmon were quantified using a large-scale acoustic tracking array in southern British Columbia, Canada. Smolts from 13 watersheds (49 watershed/species/year combinations were tagged between 2004-2008 and combined into a mixed-effects model analysis of travel speed. During the downstream migration, steelhead were slower on average than other species, possibly related to freshwater residualization. During the migration through the Strait of Georgia, coho were slower than steelhead and sockeye, likely related to some degree of inshore summer residency. Hatchery-reared smolts were slower than wild smolts during the downstream migration, but after ocean entry, average speeds were similar. In small rivers, downstream travel speed increased with body length, but in the larger Fraser River and during the coastal migration, average speed was independent of body length. Smolts leaving rivers located towards the northern end of the Strait of Georgia ecosystem migrated strictly northwards after ocean entry, but those from rivers towards the southern end displayed split-route migration patterns within populations, with some moving southward. CONCLUSIONS/SIGNIFICANCE: Our results reveal a tremendous diversity of behavioural migration strategies used by juvenile salmon, across species, rearing histories, and habitats, as well as within individual populations. During the downstream migration, factors that had strong

Laparoscopic redo fundoplication for intrathoracic migration of wrap

Directory of Open Access Journals (Sweden)

Maheshkumar G

2007-01-01

Full Text Available Laparoscopic fundoplication is fast emerging as the treatment of choice of gastro-esophageal reflux disease. However, a complication peculiar to laparoscopic surgery for this disease is the intrathoracic migration of the wrap. This article describes a case of a male patient who developed this particular complication after laparoscopic total fundoplication. Following a trauma, wrap migration occurred. The typical history and symptomatology is described. The classical Barium swallow picture is enclosed. Laparoscopic redo fundoplication was carried out. The difficulties encountered are described. Postoperative wrap migration can be suspected clinically by the presence of a precipitating event and typical symptomatology. Confirmation is by a Barium swallow. Treatment is by redo surgery.

Migration of Tundra Swans (Cygnus columbianus) Wintering in Japan Using Satellite Tracking: Identification of the Eastern Palearctic Flyway.

Science.gov (United States)

Chen, Wenbo; Doko, Tomoko; Fujita, Go; Hijikata, Naoya; Tokita, Ken-Ichi; Uchida, Kiyoshi; Konishi, Kan; Hiraoka, Emiko; Higuchi, Hiroyoshi

2016-02-01

Migration through the Eastern Palearctic (EP) flyway by tundra swans (Cygnus columbianus) has not been thoroughly documented. We satellite-tracked the migration of 16 tundra swans that winter in Japan. The objectives of this study were 1) to show the migration pattern of the EP flyway of tundra swans; 2) to compare this pattern with the migration pattern of whooper swans; and 3) to identify stopover sites that are important for these swans' conservation. Tundra swans were captured at Kutcharo Lake, Hokkaido, in 2009-2012 and satellite-tracked. A new method called the "MATCHED (Migratory Analytical Time Change Easy Detection) method" was developed. Based on median, the spring migration began on 18 April and ended on 27 May. Autumn migration began on 9 September and ended on 2 November. The median duration of the spring and autumn migrations were 48 and 50 days, respectively. The mean duration at one stopover site was 5.5 days and 6.8 days for the spring and autumn migrations, respectively. The number of stopover sites was 3.0 and 2.5 for the spring and autumn migrations, respectively. The mean travel distances for the spring and autumn migrations were 6471 and 6331 km, respectively. Seven migration routes passing Sakhalin, the Amur River, and/or Kamchatka were identified. There were 15, 32, and eight wintering, stopover, and breeding sites, respectively. The migration routes and staging areas of tundra swans partially overlap with those of whooper swans, whose migration patterns have been previously documented. The migration patterns of these two swan species that winter in Japan confirm the importance of the Amur River, Udyl' Lake, Shchastya Bay, Aniva Bay, zaliv Chayvo Lake, zal Piltun Lake, zaliv Baykal Lake, Kolyma River, Buyunda River, Sen-kyuyel' Lake, and northern coastal areas of the Sea of Okhotsk.

Performance analysis of routing protocols for IoT

Science.gov (United States)

Manda, Sridhar; Nalini, N.

2018-04-01

Internet of Things (IoT) is an arrangement of advancements that are between disciplinary. It is utilized to have compelling combination of both physical and computerized things. With IoT physical things can have personal virtual identities and participate in distributed computing. Realization of IoT needs the usage of sensors based on the sector for which IoT is integrated. For instance, in healthcare domain, IoT needs to have integration with wearable sensors used by patients. As sensor devices produce huge amount of data, often called big data, there should be efficient routing protocols in place. To the extent remote systems is worried there are some current protocols, for example, OLSR, DSR and AODV. It additionally tosses light into Trust based routing protocol for low-power and lossy systems (TRPL) for IoT. These are broadly utilized remote directing protocols. As IoT is developing round the corner, it is basic to investigate routing protocols that and evaluate their execution regarding throughput, end to end delay, and directing overhead. The execution experiences can help in settling on very much educated choices while incorporating remote systems with IoT. In this paper, we analyzed different routing protocols and their performance is compared. It is found that AODV showed better performance than other routing protocols aforementioned.

An Evolutionary Mobility Aware Multi-Objective Hybrid Routing Algorithm for Heterogeneous Wireless Sensor Networks

DEFF Research Database (Denmark)

Kulkarni, Nandkumar P.; Prasad, Neeli R.; Prasad, Ramjee

deliberation. To tackle these two problems, Mobile Wireless Sensor Networks (MWSNs) is a better choice. In MWSN, Sensor nodes move freely to a target area without the need for any special infrastructure. Due to mobility, the routing process in MWSN has become more complicated as connections in the network can...... such as Average Energy consumption, Control Overhead, Reaction Time, LQI, and HOP Count. The authors study the influence of energy heterogeneity and mobility of sensor nodes on the performance of EMRP. The Performance of EMRP compared with Simple Hybrid Routing Protocol (SHRP) and Dynamic Multi-Objective Routing...

Decision-Making in Agent-Based Models of Migration: State of the Art and Challenges.

Science.gov (United States)

Klabunde, Anna; Willekens, Frans

We review agent-based models (ABM) of human migration with respect to their decision-making rules. The most prominent behavioural theories used as decision rules are the random utility theory, as implemented in the discrete choice model, and the theory of planned behaviour. We identify the critical choices that must be made in developing an ABM, namely the modelling of decision processes and social networks. We also discuss two challenges that hamper the widespread use of ABM in the study of migration and, more broadly, demography and the social sciences: (a) the choice and the operationalisation of a behavioural theory (decision-making and social interaction) and (b) the selection of empirical evidence to validate the model. We offer advice on how these challenges might be overcome.

First description of autumn migration of Sooty Falcon Falco concolor from the United Arab Emirates to Madagascar using satellite telemetry

Science.gov (United States)

Javed, Sàlim; Douglas, David C.; Khan, Shahid Noor; Nazeer Shah, Junid; Ali Al Hammadi, Abdullah

2012-01-01

The movement and migration pattern of the 'Near Threatened' Sooty Falcon Falco concolor is poorly known. Sooty Falcons breed on the islands of the Arabian Gulf after arriving from their non-breeding areas that are mainly in Madagascar. In the first satellite tracking of the species we fitted a 9.5 g Argos solar powered transmitter on an adult breeding Sooty Falcon off the western coast of Abu Dhabi in the United Arab Emirates. The bird successfully undertook autumn migration to Madagascar, a known wintering area for the species. We document the Sooty Falcon's autumn migration route and stop-over sites. The adult Sooty Falcon initiated its migration at night and with tailwinds, and travelled mainly during daytime hours for 13 days over an inland route of more than 5,656 km. The three stop-over sites in East Africa were characterised by moderate to sparse shrub cover associated with potential sources of water. We discuss the migration pattern of the tracked bird in relation to importance of non-breeding areas for Sooty Falcons and recent declines in numbers in their breeding range.

Global crisis and the Europe-Latin America migration system

Directory of Open Access Journals (Sweden)

Susana M. Sassone

2014-09-01

Full Text Available This article discusses some of the changes in the connections of the European-Latin American migration system over the past decades. First, we analyse the changing trends and re-routing of the flows between the two ends of the system. Then, we address the complex rearrangements of immigration policies, which in both spaces are again beginning to turn inwards. Lastly, we briefly review the partnerships that are being established between Europe and Latin America via Spain. Within this framework, we wonder whether we are entering a new phase of the globalisation of migration, the dynamic of which is a pendulum with global and regional effects.

Behaviour of stocked and naturally recruited European eels during migration

DEFF Research Database (Denmark)

Westerberg, Håkan; Sjöberg, Niklas; Lagenfelt, Ingvar

2014-01-01

An objection to the stocking of translocated eels as a management measure for the European eel (Anguilla anguilla L.) is that these eels may lack the ability to find their way back to the spawning area in the Sargasso Sea because the translocation will confuse their imprinted navigation. We...... behaviour could be monitored by acoustic tagging, in addition to using archival and satellite tags to track the subsequent marine migration. In the second year, the eels were released on the open coast and only their marine migration was investigated. Eels were tracked more than 2000 km along a route that...

Spring Bird Migration Phenology in Eilat, Israel

Directory of Open Access Journals (Sweden)

Reuven Yosef

2009-12-01

Full Text Available Analysis of the mean date of first captures and median arrival dates of spring migration for 34 species of birds at Eilat, Israel, revealed that the earlier a species migrates through Eilat, the greater is the inter-annual variation in the total time of its passage. Birds arrive during spring migration in Eilat in four structured and independent waves. The annual fluctuation in the initial arrival dates (initial capture dates and median dates (median date of all captures, not including recaptures, did not depend on the length of the migratory route. This implies that migrants crossing the Sahara desert depart from their winter quarters on different Julian days in different years. We suggest that negative correlations between the median date of the spring migration of early and late migrants depends upon the easterly (Hamsin wind period. Moreover, we believe that the phenology of all birds during spring migration in Eilat is possibly also determined by external factors such as weather conditions on the African continent or global climatic processes in the Northern hemisphere. Orphean Warblers (Sylvia hortensis show a strong positive correlation (rs=-0.502 of initial capture date with calendar years, whereas other species such as Barred Warbler (S. nisoria; rs = -0.391 and Spotted Flycatcher (Muscicapa striata; rs = -0.398 display an insignificant trend. The Dead Sea Sparrow (Passer moabiticus and Red-Backed Shrike (Lanius collurio are positively correlated regarding initial arrival date and medians of spring migration.

A proper choice of route significantly reduces air pollution exposure--a study on bicycle and bus trips in urban streets.

Science.gov (United States)

Hertel, Ole; Hvidberg, Martin; Ketzel, Matthias; Storm, Lars; Stausgaard, Lizzi

2008-01-15

A proper selection of route through the urban area may significantly reduce the air pollution exposure. This is the main conclusion from the presented study. Air pollution exposure is determined for two selected cohorts along the route going from home to working place, and back from working place to home. Exposure is determined with a street pollution model for three scenarios: bicycling along the shortest possible route, bicycling along the low exposure route along less trafficked streets, and finally taking the shortest trip using public transport. Furthermore, calculations are performed for the cases the trip takes place inside as well as outside the traffic rush hours. The results show that the accumulated air pollution exposure for the low exposure route is between 10% and 30% lower for the primary pollutants (NO(x) and CO). However, the difference is insignificant and in some cases even negative for the secondary pollutants (NO(2) and PM(10)/PM(2.5)). Considering only the contribution from traffic in the travelled streets, the accumulated air pollution exposure is between 54% and 67% lower for the low exposure route. The bus is generally following highly trafficked streets, and the accumulated exposure along the bus route is therefore between 79% and 115% higher than the high exposure bicycle route (the short bicycle route). Travelling outside the rush hour time periods reduces the accumulated exposure between 10% and 30% for the primary pollutants, and between 5% and 20% for the secondary pollutants. The study indicates that a web based route planner for selecting the low exposure route through the city might be a good service for the public. In addition the public may be advised to travel outside rush hour time periods.

INDIVIDUAL BASED MODELLING APPROACH TO THERMAL REFUGE USE BY MIGRATING ADULT SALMON AND STEELHEAD

Science.gov (United States)

Diadromous fish populations in the Pacific Northwest face challenges along their migratory routes from declining habitat quality, harvest, and barriers to longitudinal connectivity. Changes in river temperature regimes are producing an additional challenge for upstream migrating ...

Migrating mule deer: effects of anthropogenically altered landscapes.

Directory of Open Access Journals (Sweden)

Patrick E Lendrum

Full Text Available Migration is an adaptive strategy that enables animals to enhance resource availability and reduce risk of predation at a broad geographic scale. Ungulate migrations generally occur along traditional routes, many of which have been disrupted by anthropogenic disturbances. Spring migration in ungulates is of particular importance for conservation planning, because it is closely coupled with timing of parturition. The degree to which oil and gas development affects migratory patterns, and whether ungulate migration is sufficiently plastic to compensate for such changes, warrants additional study to better understand this critical conservation issue.We studied timing and synchrony of departure from winter range and arrival to summer range of female mule deer (Odocoileus hemionus in northwestern Colorado, USA, which has one of the largest natural-gas reserves currently under development in North America. We hypothesized that in addition to local weather, plant phenology, and individual life-history characteristics, patterns of spring migration would be modified by disturbances associated with natural-gas extraction. We captured 205 adult female mule deer, equipped them with GPS collars, and observed patterns of spring migration during 2008-2010.Timing of spring migration was related to winter weather (particularly snow depth and access to emerging vegetation, which varied among years, but was highly synchronous across study areas within years. Additionally, timing of migration was influenced by the collective effects of anthropogenic disturbance, rate of travel, distance traveled, and body condition of adult females. Rates of travel were more rapid over shorter migration distances in areas of high natural-gas development resulting in the delayed departure, but early arrival for females migrating in areas with high development compared with less-developed areas. Such shifts in behavior could have consequences for timing of arrival on birthing areas

A cost effective topology migration path towards fibre

OpenAIRE

Phillipson, F.

2013-01-01

If an operator has as starting position a Full Copper topology in which ADSL or VDSL is offered from the Central Office, the next choice he has to make is to provide Full FttH or use an other topology option, e.g. FttCab, first as intermediate step to provide a next generation service package. In this paper we present a gradual topology migration path from Full Copper via FttCab and Hybrid FttH towards Full FttH. We look at the planning issues of this topology migration and the financial impa...

Prediction Schemes to Enhance the Routing Process in Geographical GPSR Ad Hoc Protocol

Directory of Open Access Journals (Sweden)

Raed Saqour

2007-01-01

Full Text Available Geographical routing protocols have received a serious attention due to more advantages they have in comparison to the conventional routing protocols. They require information about the physical position of nodes needed to be available. Commonly, each node determines its own position through the use of Global Positioning System (GPS or some other type of positioning service. Greedy Perimeter Stateless Routing (GPSR protocol, which is one of geographical routing protocols, limits the forwarding decision of the packet based on the node's own position, the destination's position and the position of the forwarding node's neighbors. Location information has some inaccuracy depending on the localization system and the environment exists in. This paper aims to study the impact of mobility metrics (beacon interval, and node speed on introducing location information error in GPSR protocol using different mobility models. The effect of these metrics is identified in GPSR as Neighbor Break Link (NBL problem. Based on simulation analysis, mobility prediction schemes are proposed to migrate the observed problem.

Migration intentions among Portuguese junior doctors: Results from a survey.

Science.gov (United States)

Ramos, Pedro; Alves, Hélio

2017-12-01

Migration of health personnel during periods of economic crisis represents a challenge for policymakers in origin and destination countries. Portugal is going through a period of economic hardship and much has been speculated about an increase in junior doctors' migration during this period. Using a questionnaire administered to a sample of Portuguese junior doctors who were still in the general residency (1st-year after medical school), we aim at determining the prevalence of migration intentions among Portuguese junior doctors and to identify the most important drivers of career choice for those who are considering emigrating in the near future. In our sample, 55% of Portuguese junior doctors are considering working abroad in the coming 10 years. Several variables were associated with an intention to work abroad: female sex (odds ratio [OR] 0.559; 95% confidence interval [CI] 0.488-0.640), the National Medical Exam score (OR 0.978; 95% CI 0.961-0.996;), having studied abroad (OR 1.756; 95% CI 1.086-2.867) and considering income and research opportunities as key factors for future specialty choice (OR 1.356; 95% CI 1.132-1.626; OR 2.626; 95% CI 1.228-4.172). Our study warns of the shortages the country may face due to doctors' migration and the main factors behind migration intentions in Portugal. Developing physician retention strategies is a priority to appropriately address these factors. Copyright © 2017 Elsevier B.V. All rights reserved.

Migration strategies of Swan Geese Anser cygnoides from northeast Mongolia

Science.gov (United States)

Batbayar, Nyambayar; Takekawa, John Y.; Newman, Scott H.; Prosser, Diann J.; Natsagdorj, Tseveenmyadag; Xiao, Xiangming

2011-01-01

In 2006–2008, 25 Swan Geese Anser cygnoides were marked with solar-powered GPS satellite transmitters in northeast Mongolia to examine the timing and pathways of their migration. Most geese began their autumn migration in August, flying southeast toward a staging area at the Yalu River Estuary on the China-North Korea border. After staging for several weeks, the Swan Geese continued to their wintering grounds at wetlands along the Yangtze River Basin of eastern China in December. Spring migration commenced in late February, and the birds following either a same-route or loop migration to arrive at the breeding grounds in mid April. Swan Geese used a larger number of staging areas for a longer duration when they were north of 42°N latitude; they seemed to avoid staging for extended periods in the highly urbanised areas of eastern China. Further research should examine threats and disturbances to the geese in relation to human population growth and increasing urbanisation.

Nationwide genetic surveillance of Plasmodium vivax in Papua New Guinea reveals heterogeneous transmission dynamics and routes of migration amongst subdivided populations.

Science.gov (United States)

Fola, Abebe A; Nate, Elma; Abby Harrison, G L; Barnadas, Céline; Hetzel, Manuel W; Iga, Jonah; Siba, Peter; Mueller, Ivo; Barry, Alyssa E

2018-03-01

The Asia Pacific Leaders in Malaria Alliance (APLMA) have committed to eliminate malaria from the region by 2030. Papua New Guinea (PNG) has the highest malaria burden in the Asia-Pacific region but with the intensification of control efforts since 2005, transmission has been dramatically reduced and Plasmodium vivax is now the dominant malaria infection in some parts of the country. To gain a better understanding of the transmission dynamics and migration patterns of P. vivax in PNG, here we investigate population structure in eight geographically and ecologically distinct regions of the country. A total of 219 P. vivax isolates (16-30 per population) were successfully haplotyped using 10 microsatellite markers. A wide range of genetic diversity (H e =0.37-0.87, R s =3.60-7.58) and significant multilocus linkage disequilibrium (LD) was observed in six of the eight populations (I A S =0.08-0.15 p-value<0.05) reflecting a spectrum of transmission intensities across the country. Genetic differentiation between regions was evident (Jost's D=0.07-0.72), with increasing divergence of populations with geographic distance. Overall, P. vivax isolates clustered into three major genetic populations subdividing the Mainland lowland and coastal regions, the Islands and the Highlands. P. vivax gene flow follows major human migration routes, and there was higher gene flow amongst Mainland parasite populations than among Island populations. The Central Province (samples collected in villages close to the capital city, Port Moresby), acts as a sink for imported infections from the three major endemic areas. These insights into P. vivax transmission dynamics and population networks will inform targeted strategies to contain malaria infections and to prevent the spread of drug resistance in PNG. Copyright © 2017 Elsevier B.V. All rights reserved.

Trans-equatorial migration routes, staging sites and wintering areas of a high-Arctic avian predator: the long-tailed Skua (Stercorarius longicaudus).

Science.gov (United States)

Gilg, Olivier; Moe, Børge; Hanssen, Sveinn Are; Schmidt, Niels Martin; Sittler, Benoît; Hansen, Jannik; Reneerkens, Jeroen; Sabard, Brigitte; Chastel, Olivier; Moreau, Jérôme; Phillips, Richard A; Oudman, Thomas; Biersma, Elisabeth M; Fenstad, Anette A; Lang, Johannes; Bollache, Loïc

2013-01-01

The Long-tailed Skua, a small (summer, but little is known about its migration and winter distribution. We used light-level geolocators to track the annual movements of eight adult birds breeding in north-east Greenland (n = 3) and Svalbard (n = 5). All birds wintered in the Southern Hemisphere (mean arrival-departure dates on wintering grounds: 24 October-21 March): five along the south-west coast of Africa (0-40°S, 0-15°E), in the productive Benguela upwelling, and three further south (30-40°S, 0-50°E), in an area extending into the south-west Indian Ocean. Different migratory routes and rates of travel were documented during post-breeding (345 km d(-1) in late August-early September) and spring migrations (235 km d(-1) in late April) when most birds used a more westerly flyway. Among the different staging areas, a large region off the Grand Banks of Newfoundland appears to be the most important. It was used in autumn by all but one of the tracked birds (from a few days to three weeks) and in spring by five out of eight birds (from one to more than six weeks). Two other staging sites, off the Iberian coast and near the Azores, were used by two birds in spring for five to six weeks. Over one year, individuals travelled between 43,900 and 54,200 km (36,600-45,700 when excluding staging periods) and went as far as 10,500-13,700 km (mean 12,800 km) from their breeding sites. This study has revealed important marine areas in both the south and north Atlantic Ocean. Sustainable management of these ocean basins will benefit Long-tailed Skuas as well as other trans-equatorial migrants from the Arctic.

Street Choice Logit Model for Visitors in Shopping Districts

Science.gov (United States)

Kawada, Ko; Yamada, Takashi; Kishimoto, Tatsuya

2014-01-01

In this study, we propose two models for predicting people’s activity. The first model is the pedestrian distribution prediction (or postdiction) model by multiple regression analysis using space syntax indices of urban fabric and people distribution data obtained from a field survey. The second model is a street choice model for visitors using multinomial logit model. We performed a questionnaire survey on the field to investigate the strolling routes of 46 visitors and obtained a total of 1211 street choices in their routes. We proposed a utility function, sum of weighted space syntax indices, and other indices, and estimated the parameters for weights on the basis of maximum likelihood. These models consider both street networks, distance from destination, direction of the street choice and other spatial compositions (numbers of pedestrians, cars, shops, and elevation). The first model explains the characteristics of the street where many people tend to walk or stay. The second model explains the mechanism underlying the street choice of visitors and clarifies the differences in the weights of street choice parameters among the various attributes, such as gender, existence of destinations, number of people, etc. For all the attributes considered, the influences of DISTANCE and DIRECTION are strong. On the other hand, the influences of Int.V, SHOPS, CARS, ELEVATION, and WIDTH are different for each attribute. People with defined destinations tend to choose streets that “have more shops, and are wider and lower”. In contrast, people with undefined destinations tend to choose streets of high Int.V. The choice of males is affected by Int.V, SHOPS, WIDTH (positive) and CARS (negative). Females prefer streets that have many shops, and couples tend to choose downhill streets. The behavior of individual persons is affected by all variables. The behavior of people visiting in groups is affected by SHOP and WIDTH (positive). PMID:25379274

Street Choice Logit Model for Visitors in Shopping Districts

Directory of Open Access Journals (Sweden)

Ko Kawada

2014-07-01

Full Text Available In this study, we propose two models for predicting people’s activity. The first model is the pedestrian distribution prediction (or postdiction model by multiple regression analysis using space syntax indices of urban fabric and people distribution data obtained from a field survey. The second model is a street choice model for visitors using multinomial logit model. We performed a questionnaire survey on the field to investigate the strolling routes of 46 visitors and obtained a total of 1211 street choices in their routes. We proposed a utility function, sum of weighted space syntax indices, and other indices, and estimated the parameters for weights on the basis of maximum likelihood. These models consider both street networks, distance from destination, direction of the street choice and other spatial compositions (numbers of pedestrians, cars, shops, and elevation. The first model explains the characteristics of the street where many people tend to walk or stay. The second model explains the mechanism underlying the street choice of visitors and clarifies the differences in the weights of street choice parameters among the various attributes, such as gender, existence of destinations, number of people, etc. For all the attributes considered, the influences of DISTANCE and DIRECTION are strong. On the other hand, the influences of Int.V, SHOPS, CARS, ELEVATION, and WIDTH are different for each attribute. People with defined destinations tend to choose streets that “have more shops, and are wider and lower”. In contrast, people with undefined destinations tend to choose streets of high Int.V. The choice of males is affected by Int.V, SHOPS, WIDTH (positive and CARS (negative. Females prefer streets that have many shops, and couples tend to choose downhill streets. The behavior of individual persons is affected by all variables. The behavior of people visiting in groups is affected by SHOP and WIDTH (positive.

Eco-routing: More green drivers means more benefits?

Energy Technology Data Exchange (ETDEWEB)

Valdes Serrano, C.; Perez Prada, F.; Monzon de Caceres, A.

2016-07-01

Information and Communications Technology (ICT)/Information and Technology Services (ITS) can play an important role in the transport sector, helping in maintaining accessibility and contemporarily optimizing the use of the vehicles. Among these ICT measures, eco-routing seems a promising one. Drivers normally follow the route which minimizes their generalized costs, normally time and money. But environmental concern is increasing, and drivers are starting to think about the effects of their driving. This means including CO2 emissions or fuel consumption in their route choice. But is this always positive, independently of the traffic situation and the penetration level of green drivers? This articles aims to analyze what happens in terms of fuel consumption, CO2 emissions and travel time, when different penetration levels of drivers, and with different traffic situations, follow the route of minimum fuel consumption instead of the conventional generalized costs. The analysis is based on a modelling process using a transport model of the whole region of Madrid. A total of 18 scenarios are considered: 3 reference scenarios (for congested, medium and low flow traffic situations), and 5 different penetration levels of green drivers for each traffic situation. Results show how impact varies substantially with the level of traffic and, also, that the more the best is not always true. (Author)

Migration waves to the Baltic Sea region.

Science.gov (United States)

Lappalainen, T; Laitinen, V; Salmela, E; Andersen, P; Huoponen, K; Savontaus, M-L; Lahermo, P

2008-05-01

In this study, the population history of the Baltic Sea region, known to be affected by a variety of migrations and genetic barriers, was analyzed using both mitochondrial DNA and Y-chromosomal data. Over 1200 samples from Finland, Sweden, Karelia, Estonia, Setoland, Latvia and Lithuania were genotyped for 18 Y-chromosomal biallelic polymorphisms and 9 STRs, in addition to analyzing 17 coding region polymorphisms and the HVS1 region from the mtDNA. It was shown that the populations surrounding the Baltic Sea are genetically similar, which suggests that it has been an important route not only for cultural transmission but also for population migration. However, many of the migrations affecting the area from Central Europe, the Volga-Ural region and from Slavic populations have had a quantitatively different impact on the populations, and, furthermore, the effects of genetic drift have increased the differences between populations especially in the north. The possible explanations for the high frequencies of several haplogroups with an origin in the Iberian refugia (H1, U5b, I1a) are also discussed.

Wind conditions and geography shape the first outbound migration of juvenile honey buzzards and their distribution across sub-Saharan Africa.

Science.gov (United States)

Vansteelant, W M G; Kekkonen, J; Byholm, P

2017-05-31

Contemporary tracking studies reveal that low migratory connectivity between breeding and non-breeding ranges is common in migrant landbirds. It is unclear, however, how internal factors and early-life experiences of individual migrants shape the development of their migration routes and concomitant population-level non-breeding distributions. Stochastic wind conditions and geography may determine whether and where migrants end up by the end of their journey. We tested this hypothesis by satellite-tagging 31 fledgling honey buzzards Pernis apivorus from southern Finland and used a global atmospheric reanalysis model to estimate the wind conditions they encountered on their first outbound migration. Migration routes diverged rapidly upon departure and the birds eventually spread out across 3340 km of longitude. Using linear regression models, we show that the birds' longitudinal speeds were strongly affected by zonal wind speed, and negatively affected by latitudinal wind, with significant but minor differences between individuals. Eventually, 49% of variability in the birds' total longitudinal displacements was accounted for by wind conditions on migration. Some birds circumvented the Baltic Sea via Scandinavia or engaged in unusual downwind movements over the Mediterranean, which also affected the longitude at which these individuals arrived in sub-Saharan Africa. To understand why adult migrants use the migration routes and non-breeding sites they use, we must take into account the way in which wind conditions moulded their very first journeys. Our results present some of the first evidence into the mechanisms through which low migratory connectivity emerges. © 2017 The Authors.

Wind conditions and geography shape the first outbound migration of juvenile honey buzzards and their distribution across sub-Saharan Africa

Science.gov (United States)

Kekkonen, J.; Byholm, P.

2017-01-01

Contemporary tracking studies reveal that low migratory connectivity between breeding and non-breeding ranges is common in migrant landbirds. It is unclear, however, how internal factors and early-life experiences of individual migrants shape the development of their migration routes and concomitant population-level non-breeding distributions. Stochastic wind conditions and geography may determine whether and where migrants end up by the end of their journey. We tested this hypothesis by satellite-tagging 31 fledgling honey buzzards Pernis apivorus from southern Finland and used a global atmospheric reanalysis model to estimate the wind conditions they encountered on their first outbound migration. Migration routes diverged rapidly upon departure and the birds eventually spread out across 3340 km of longitude. Using linear regression models, we show that the birds' longitudinal speeds were strongly affected by zonal wind speed, and negatively affected by latitudinal wind, with significant but minor differences between individuals. Eventually, 49% of variability in the birds' total longitudinal displacements was accounted for by wind conditions on migration. Some birds circumvented the Baltic Sea via Scandinavia or engaged in unusual downwind movements over the Mediterranean, which also affected the longitude at which these individuals arrived in sub-Saharan Africa. To understand why adult migrants use the migration routes and non-breeding sites they use, we must take into account the way in which wind conditions moulded their very first journeys. Our results present some of the first evidence into the mechanisms through which low migratory connectivity emerges. PMID:28539514

The differential role of social networks. Strategies and routes in Brazilian migration to Portugal and the Netherlands

NARCIS (Netherlands)

M.J. van Meeteren (Masja); S. Pereira (Sonia)

2013-01-01

textabstractAbstract This paper draws on qualitative and quantitative data on the migration experiences of Brazilians living in Portugal and the Netherlands to reflect and expand upon the existing knowledge on the role of social networks in migration processes. We consider different migrant profiles

Predicted impact of barriers to migration on the Serengeti wildebeest population.

Directory of Open Access Journals (Sweden)

Ricardo M Holdo

Full Text Available The Serengeti wildebeest migration is a rare and spectacular example of a once-common biological phenomenon. A proposed road project threatens to bisect the Serengeti ecosystem and its integrity. The precautionary principle dictates that we consider the possible consequences of a road completely disrupting the migration. We used an existing spatially-explicit simulation model of wildebeest movement and population dynamics to explore how placing a barrier to migration across the proposed route (thus creating two disjoint but mobile subpopulations might affect the long-term size of the wildebeest population. Our simulation results suggest that a barrier to migration--even without causing habitat loss--could cause the wildebeest population to decline by about a third. The driver of this decline is the effect of habitat fragmentation (even without habitat loss on the ability of wildebeest to effectively track temporal shifts in high-quality forage resources across the landscape. Given the important role of the wildebeest migration for a number of key ecological processes, these findings have potentially important ramifications for ecosystem biodiversity, structure, and function in the Serengeti.

Landbird migration in the American West: Recent progress and future research directions

Science.gov (United States)

Carlisle, J.D.; Skagen, S.K.; Kus, B.E.; van Riper, Charles; Paxton, K.L.; Kelly, J.F.

2009-01-01

Our knowledge of avian behaviors during the nonbreeding period still lags behind that of the breeding season, but the last decade has witnessed a proliferation in research that has yielded significant progress in understanding migration patterns of North American birds. And, although historically the great majority of migration research has been conducted in the eastern half of the continent, there has been much recent progress on aspects of avian migration in the West. In particular, expanded use of techniques such as radar, plasma metabolites, mist-netting, count surveys, stable isotopes, genetic data, and animal tracking, coupled with an increase in multi-investigator collaborations, have all contributed to this growth of knowledge. There is increasing recognition that migration is likely the most limiting time of year for migratory birds, increasing the importance of continuing to decipher patterns of stopover ecology, identifying critical stopover habitats, and documenting migration routes in the diverse and changing landscapes of the American West. Here, we review and briefly synthesize the latest findings and advances in avian migration and consider research needs to guide future research on migration in the West. ?? 2009 by The Cooper Ornithological Society. All rights reserved.

Intermingling and seasonal migrations of Greenland halibut ( Reinhardtius hippoglossoides ) populations determined from tagging studies

DEFF Research Database (Denmark)

Boje, Jesper

2002-01-01

A total of 7244 Greenland halibut (Reinhardtius hippoglossoides' Walbaum) were tagged in Greenland waters between 1986 and 1998 to increase information on stock delineations, to clarify migration routes, and to describe the seasonal movements of cord populations. At present 517 recaptured Greenla...

Why sub-Saharan African health workers migrate to European countries that do not actively recruit: a qualitative study post-migration.

Science.gov (United States)

Poppe, Annelien; Jirovsky, Elena; Blacklock, Claire; Laxmikanth, Pallavi; Moosa, Shabir; De Maeseneer, Jan; Kutalek, Ruth; Peersman, Wim

2014-01-01

Many studies have investigated the migration intentions of sub-Saharan African medical students and health professionals within the context of a legacy of active international recruitment by receiving countries. However, many health workers migrate outside of this recruitment paradigm. This paper aims to explore the reasons for migration of health workers from sub-Saharan Africa to Belgium and Austria; European countries without a history of active recruitment in sub-Saharan Africa. Data were collected using semistructured interviews. Twenty-seven health workers were interviewed about their migration experiences. Included participants were born in sub-Saharan Africa, had trained as health workers in sub-Saharan Africa, and were currently living in Belgium or Austria, though not necessarily currently working as a health professional. Both Austria and Belgium were shown not to be target countries for the health workers, who instead moved there by circumstance, rather than choice. Three principal reasons for migration were reported: 1) educational purposes; 2) political instability or insecurity in their country of origin; and 3) family reunification. In addition, two respondents mentioned medical reasons and, although less explicit, economic factors were also involved in several of the respondents' decision to migrate. These results highlight the importance of the broader economic, social, and political context within which migration decisions are made. Training opportunities proved to be an important factor for migration. A further development and upgrade of primary care might help to counter the common desire to specialize and improve domestic training opportunities.

Differential regulation of microtubule severing by APC underlies distinct patterns of projection neuron and interneuron migration

Science.gov (United States)

Eom, Tae-Yeon; Stanco, Amelia; Guo, Jiami; Wilkins, Gary; Deslauriers, Danielle; Yan, Jessica; Monckton, Chase; Blair, Josh; Oon, Eesim; Perez, Abby; Salas, Eduardo; Oh, Adrianna; Ghukasyan, Vladimir; Snider, William D.; Rubenstein, John L. R.; Anton, E. S.

2014-01-01

Coordinated migration of distinct classes of neurons to appropriate positions leads to the formation of functional neuronal circuitry in the cerebral cortex. Two major classes of cortical neurons, interneurons and projection neurons, utilize distinctly different modes (radial vs. tangential) and routes of migration to arrive at their final positions in the cerebral cortex. Here, we show that adenomatous polyposis coli (APC) modulates microtubule (MT) severing in interneurons to facilitate tangential mode of interneuron migration, but not the glial-guided, radial migration of projection neurons. APC regulates the stability and activity of the MT severing protein p60-katanin in interneurons to promote the rapid remodeling of neuronal processes necessary for interneuron migration. These findings reveal how severing and restructuring of MTs facilitate distinct modes of neuronal migration necessary for laminar organization of neurons in the developing cerebral cortex. PMID:25535916

The migration of 111Indium-labelled polymorphonuclear leucocytes into the oral cavity in the rhesus monkey

International Nuclear Information System (INIS)

Scully, C.; Challacombe, S.J.

1979-01-01

The route of migration of polymorphonuclear leucocytes (PMNL) from blood to the oral cavity was examined in rhesus monkeys. PMNL were isolated from the peripheral blood of eleven rhesus monkeys by dextran sedimentation, radiolabelled with 111 Indium and administered intravenously. Sequential samples of crevicular fluid washings (CFW), mixed and parotid saliva and mucosal washings were taken after injection of the labelled PMNL and harvested on glass fibre discs. Highest numbers of labelled PMNL were detected in CFW. CEll-associated radioactivity was detected in CFW within 20 min of injection of labelled PMNL and reached a maximal level 1 hour after injection. PMNL were found in CFW from monkeys with clinically normal gingiva but the number of labelled PMNL in CFW increased with increasing gingival index. Significant number of PMNL migrated into mixed saliva within 30 min, and low numbers of PMNL were detected in mucosal washings and in parotid saliva after 30 min. The results indicate that the migration time of the PMNL from blood to the oral cavity is less than 30 min, irrespective of the gingival index, that the gingival crevice is the main route of entry of PMNL to the oral cavity and that the numbers of PMNL migrating to the crevice increase as the gingival index rises. (author)

Interdependence of macrophage migration and ventral nerve cord development in Drosophila embryos.

Science.gov (United States)

Evans, Iwan R; Hu, Nan; Skaer, Helen; Wood, Will

2010-05-01

During embryonic development, Drosophila macrophages (haemocytes) undergo a series of stereotypical migrations to disperse throughout the embryo. One major migratory route is along the ventral nerve cord (VNC), where haemocytes are required for the correct development of this tissue. We show, for the first time, that a reciprocal relationship exists between haemocytes and the VNC and that defects in nerve cord development prevent haemocyte migration along this structure. Using live imaging, we demonstrate that the axonal guidance cue Slit and its receptor Robo are both required for haemocyte migration, but signalling is not autonomously required in haemocytes. We show that the failure of haemocyte migration along the VNC in slit mutants is not due to a lack of chemotactic signals within this structure, but rather to a failure in its detachment from the overlying epithelium, creating a physical barrier to haemocyte migration. This block of haemocyte migration in turn disrupts the formation of the dorsoventral channels within the VNC, further highlighting the importance of haemocyte migration for correct neural development. This study illustrates the important role played by the three-dimensional environment in directing cell migration in vivo and reveals an intriguing interplay between the developing nervous system and the blood cells within the fly, demonstrating that their development is both closely coupled and interdependent.

Least-squares migration of multisource data with a deblurring filter

KAUST Repository

Dai, Wei; Wang, Xin; Schuster, Gerard T.

2011-01-01

Least-squares migration (LSM) has been shown to be able to produce high-quality migration images, but its computational cost is considered to be too high for practical imaging. We have developed a multisource least-squares migration algorithm (MLSM) to increase the computational efficiency by using the blended sources processing technique. To expedite convergence, a multisource deblurring filter is used as a preconditioner to reduce the data residual. This MLSM algorithm is applicable with Kirchhoff migration, wave-equation migration, or reverse time migration, and the gain in computational efficiency depends on the choice of migration method. Numerical results with Kirchhoff LSM on the 2D SEG/EAGE salt model show that an accurate image is obtained by migrating a supergather of 320 phase-encoded shots. When the encoding functions are the same for every iteration, the input/output cost of MLSM is reduced by 320 times. Empirical results show that the crosstalk noise introduced by blended sources is more effectively reduced when the encoding functions are changed at every iteration. The analysis of signal-to-noise ratio (S/N) suggests that not too many iterations are needed to enhance the S/N to an acceptable level. Therefore, when implemented with wave-equation migration or reverse time migration methods, the MLSM algorithm can be more efficient than the conventional migration method. © 2011 Society of Exploration Geophysicists.

Least-squares migration of multisource data with a deblurring filter

KAUST Repository

Dai, Wei

2011-09-01

Least-squares migration (LSM) has been shown to be able to produce high-quality migration images, but its computational cost is considered to be too high for practical imaging. We have developed a multisource least-squares migration algorithm (MLSM) to increase the computational efficiency by using the blended sources processing technique. To expedite convergence, a multisource deblurring filter is used as a preconditioner to reduce the data residual. This MLSM algorithm is applicable with Kirchhoff migration, wave-equation migration, or reverse time migration, and the gain in computational efficiency depends on the choice of migration method. Numerical results with Kirchhoff LSM on the 2D SEG/EAGE salt model show that an accurate image is obtained by migrating a supergather of 320 phase-encoded shots. When the encoding functions are the same for every iteration, the input/output cost of MLSM is reduced by 320 times. Empirical results show that the crosstalk noise introduced by blended sources is more effectively reduced when the encoding functions are changed at every iteration. The analysis of signal-to-noise ratio (S/N) suggests that not too many iterations are needed to enhance the S/N to an acceptable level. Therefore, when implemented with wave-equation migration or reverse time migration methods, the MLSM algorithm can be more efficient than the conventional migration method. © 2011 Society of Exploration Geophysicists.

Migration and winter distribution of the Chestnutcollared Longspur

Directory of Open Access Journals (Sweden)

Ellison Kevin

2017-12-01

Full Text Available The Chestnut-collared Longspur (Calcarius ornatus is one of five grassland songbirds, endemic within North America, with populations that have declined >65% since the 1960s. These species breed and winter in the northern and southern Great Plains, respectively. Identifying migration routes, wintering sites, and the timing of their habitat use is key for understanding the relative magnitude of threats across the annual cycle and effectively targeting habitats for conservation. We tracked migratory movements of seven Chestnut-collared Longspurs with light-level geolocators deployed in Canada. Individuals wintered up to 112-1,200km apart. All followed the Central Flyway, circumvented high-elevation terrain, and traveled east of the breeding location. Unlike most songbirds, the durations of spring and fall migrations were similar; on average 42 ± 7d and 41 ± 5d during fall and spring migrations, respectively, for an approximately 2,000km migration; this highlights the need to better understand habitat requirements during migration for grassland songbirds. Using geospatial habitat data, we assessed winter distribution overlap with four other endemic grassland songbirds; wintering range overlapped 63-99%. Future studies should use more precise devices (e.g., archival GPS units, programmed for data collection dates from this study, to identify specific migratory sites for better conserving this and associated grassland species.

Evaluation of connected vehicle impact on mobility and mode choice

Directory of Open Access Journals (Sweden)

Simon Minelli

2015-10-01

Full Text Available Connected vehicle is emerging as a solution to exacerbating congestion problems in urban areas. It is important to understand the impacts of connected vehicle on network and travel behavior of road users. The main objective of this paper is to evaluate the impact of connected vehicle on the mode choice and mobility of transportation networks. An iterative methodology was used in this paper where demands for various modes were modified based on the changes in travel time between each origin-destination (OD pair caused by introduction of connected vehicle. Then a traffic assignment was performed in a micro-simulation model, which was able to accurately simulate vehicle-to-vehicle communication. It is assumed that vehicles are equipped with a dynamic route guidance technology to choose their own route using real-time traffic information obtained through communication. The travel times obtained from the micro-simulation model were compared with a base scenario with no connected vehicle. The methodology was tested for a portion of Downtown Toronto, Ontario, Canada. In order to quantify changes in mode share with changes in travel time associated with each OD pair, mode choice models were developed for auto, transit, cycling and pedestrians using data mainly from the Transportation Tomorrow Survey. The impact of connected vehicle on mode choice was evaluated for different market penetrations of connected vehicle. The results of this study show that average travel times for the whole auto mode will generally increase, with the largest increase from connected vehicles. This causes an overall move away from the auto mode for high market penetrations if a dynamic route guidance algorithm is implemented.

Research on Strategy Control of Taxi Carpooling Detour Route under Uncertain Environment

Directory of Open Access Journals (Sweden)

Wei Zhang

2016-01-01

Full Text Available For the problem of route choice in taxi carpooling detour, considering the uncertainty of traffic and the characteristic of passengers’ noncomplete rationality, an evolutionary game model of taxi carpooling detour route is built, in which prospect theory is introduced and revenue of strategy is replaced by prospect value. The model reflects more really decision-making psychology of passengers. Then the stable strategies of the model are studied, and the influences of detour distance and traffic congestion on detour carpooling success are analyzed, respectively. The results show that when at least one route of which prospect values for two passenger sides are both positive exists, carpooling route can reach an agreement. The route is stable strategy of evolutionary game, and the passengers requiring short travel time tend to select the nondetour route. With the increase of detour distance and traffic congestion rate, the possibility of reaching an agreement decreases gradually; that is, possibility of carpooling failure increases. So taxi carpooling detour is possible under the certain condition, but some measures must be carried out such as constraints of detour distance and mitigation of traffic congestion to improve carpooling success probability. These conclusions have a certain guiding significance to the formulation of taxi carpooling policy.

Sex in the City: Prostitution in the Age of Global Migrations

Directory of Open Access Journals (Sweden)

Lillian S. Robinson

2012-06-01

Full Text Available The article traces the history and current role of gendered migration and sexual labor through an exploration of the contradictions inherent in gendered migration in which rural youth are migrating to the cities of the developing world while sex-customers migrate to “hot” tourism destinations. The author focuses on the economic nature of this migration within the context of the two main concepts used to understand women’s migration: refugees and trafficking. Case studies, particularly from Asia, reveal that a blanket application of the trafficking label misinterprets the agency, daily life, and even the oppression of sex workers. By examining the factors that influence women’s migration for work and the conditions that perpetuate their entrance into the sex industry, the author concludes that there is need to take into account the limited choices in today’s global economy that compel women to engage in sex work. She questions therefore the utility, in developed countries, of criminalizing these activities, suggesting instead that they be protected by extending their rights.

Local ecological knowledge of fishers about the life cycle and temporal patterns in the migration of mullet (Mugil liza in Southern Brazil

Directory of Open Access Journals (Sweden)

Dannieli Firme Herbst

Full Text Available This research investigates local ecological knowledge of fishers in communities along a latitudinal gradient in the coast of the Santa Catarina State, regarding the life cycle of mullets Mugil liza (migration, feeding, and reproductive behavior. Our sampling encompassed eight Santa Catarina coastal cities (nine artisanal fishing sites and engaged 45 key informants (28- 86 years of age through semi-structured interviews from August/2011 to March/2012. This fish species feeds and grows in lagoon and estuarine systems, migrating to the sea for reproduction, and spawning. Fishers acknowledged the Patos Lagoon and the Plata River as the main source of mullet schools. Migration occurs from South to North and the routes vary according to climatic and oceanographic conditions (e.g., low temperatures, south winds, rainfall, currents, salinity. These conditions influence the abundance of mullets (and therefore fisheries success, their migration and stops in locations such as beaches, rocky shores, and islands. According to fishers, mullet spawning occurs throughout the coast of the Santa Catarina State and they feed in lagoons and riverine systems but also out at sea during migration. In conclusion, fishers possess a detailed knowledge about mullet life cycle and they identify intra and interannual variations in migration routes, a pattern that should be considered in managing the fishery.

The Great Migration and African-American Genomic Diversity.

Directory of Open Access Journals (Sweden)

Soheil Baharian

2016-05-01

Full Text Available We present a comprehensive assessment of genomic diversity in the African-American population by studying three genotyped cohorts comprising 3,726 African-Americans from across the United States that provide a representative description of the population across all US states and socioeconomic status. An estimated 82.1% of ancestors to African-Americans lived in Africa prior to the advent of transatlantic travel, 16.7% in Europe, and 1.2% in the Americas, with increased African ancestry in the southern United States compared to the North and West. Combining demographic models of ancestry and those of relatedness suggests that admixture occurred predominantly in the South prior to the Civil War and that ancestry-biased migration is responsible for regional differences in ancestry. We find that recent migrations also caused a strong increase in genetic relatedness among geographically distant African-Americans. Long-range relatedness among African-Americans and between African-Americans and European-Americans thus track north- and west-bound migration routes followed during the Great Migration of the twentieth century. By contrast, short-range relatedness patterns suggest comparable mobility of ∼15-16km per generation for African-Americans and European-Americans, as estimated using a novel analytical model of isolation-by-distance.

The European Refugee Crisis from the Perspective of International Migration Governance

Directory of Open Access Journals (Sweden)

Xie Tingting

2015-11-01

Full Text Available The influx of refugees in Europe in 2015 has greatly increased, which not only affects the stability and unity of European society, but also exerts certain pressure on its economic development. In the face of the refugee crisis, it is a dilemma for the European countries to choose either humanitarian or national interests. Starting from the impact and challenge that international migration has had on effective governance within national boundaries, this paper uses the theories of international migration to analyze the three basic choices. Further, the authors provide a new way of thinking about the European refugee crisis from the perspective of international migration governance mechanisms. Of course, China should seize the opportunity to become an advocate of the international migration governance mechanism and rule maker of the global governance.

The European Refugee Crisis from the Perspective of International Migration Governance

Directory of Open Access Journals (Sweden)

Xie Tingting

2015-12-01

Full Text Available The influx of refugees in Europe in 2015 has greatly increased, which not only affects the stability and unity of European society, but also exerts certain pressure on its economic development. In the face of the refugee crisis, it is a dilemma for the European countries to choose either humanitarian or national interests. Starting from the impact and challenge that international migration has had on effective governance within national boundaries, this paper uses the theories of international migration to analyze the three basic choices. Further, the authors provide a new way of thinking about the European refugee crisis from the perspective of international migration governance mechanisms. Of course, China should seize the opportunity to become an advocate of the international migration governance mechanism and rule maker of the global governance.

Uniform Page Migration Problem in Euclidean Space

Directory of Open Access Journals (Sweden)

Amanj Khorramian

2016-08-01

Full Text Available The page migration problem in Euclidean space is revisited. In this problem, online requests occur at any location to access a single page located at a server. Every request must be served, and the server has the choice to migrate from its current location to a new location in space. Each service costs the Euclidean distance between the server and request. A migration costs the distance between the former and the new server location, multiplied by the page size. We study the problem in the uniform model, in which the page has size D = 1 . All request locations are not known in advance; however, they are sequentially presented in an online fashion. We design a 2.75 -competitive online algorithm that improves the current best upper bound for the problem with the unit page size. We also provide a lower bound of 2.732 for our algorithm. It was already known that 2.5 is a lower bound for this problem.

Global spatio-temporal patterns in human migration: a complex network perspective.

Science.gov (United States)

Davis, Kyle F; D'Odorico, Paolo; Laio, Francesco; Ridolfi, Luca

2013-01-01

Migration is a powerful adaptive strategy for humans to navigate hardship and pursue a better quality of life. As a universal vehicle facilitating exchanges of ideas, culture, money and goods, international migration is a major contributor to globalization. Consisting of countries linked by multiple connections of human movements, global migration constitutes a network. Despite the important role of human migration in connecting various communities in different parts of the world, the topology and behavior of the international migration network and its changes through time remain poorly understood. Here we show that the global human migration network became more interconnected during the latter half of the twentieth century and that migrant destination choice partly reflects colonial and postcolonial histories, language, religion, and distances. From 1960 to 2000 we found a steady increase in network transitivity (i.e. connectivity between nodes connected to the same node), a decrease in average path length and an upward shift in degree distribution, all of which strengthened the 'small-world' behavior of the migration network. Furthermore, we found that distinct groups of countries preferentially interact to form migration communities based largely on historical, cultural and economic factors.

Global spatio-temporal patterns in human migration: a complex network perspective.

Directory of Open Access Journals (Sweden)

Kyle F Davis

Full Text Available Migration is a powerful adaptive strategy for humans to navigate hardship and pursue a better quality of life. As a universal vehicle facilitating exchanges of ideas, culture, money and goods, international migration is a major contributor to globalization. Consisting of countries linked by multiple connections of human movements, global migration constitutes a network. Despite the important role of human migration in connecting various communities in different parts of the world, the topology and behavior of the international migration network and its changes through time remain poorly understood. Here we show that the global human migration network became more interconnected during the latter half of the twentieth century and that migrant destination choice partly reflects colonial and postcolonial histories, language, religion, and distances. From 1960 to 2000 we found a steady increase in network transitivity (i.e. connectivity between nodes connected to the same node, a decrease in average path length and an upward shift in degree distribution, all of which strengthened the 'small-world' behavior of the migration network. Furthermore, we found that distinct groups of countries preferentially interact to form migration communities based largely on historical, cultural and economic factors.

Route Monopolie and Optimal Nonlinear Pricing

Science.gov (United States)

Tournut, Jacques

2003-01-01

To cope with air traffic growth and congested airports, two solutions are apparent on the supply side: 1) use larger aircraft in the hub and spoke system; or 2) develop new routes through secondary airports. An enlarged route system through secondary airports may increase the proportion of route monopolies in the air transport market.The monopoly optimal non linear pricing policy is well known in the case of one dimension (one instrument, one characteristic) but not in the case of several dimensions. This paper explores the robustness of the one dimensional screening model with respect to increasing the number of instruments and the number of characteristics. The objective of this paper is then to link and fill the gap in both literatures. One of the merits of the screening model has been to show that a great varieD" of economic questions (non linear pricing, product line choice, auction design, income taxation, regulation...) could be handled within the same framework.VCe study a case of non linear pricing (2 instruments (2 routes on which the airline pro_ddes customers with services), 2 characteristics (demand of services on these routes) and two values per characteristic (low and high demand of services on these routes)) and we show that none of the conclusions of the one dimensional analysis remain valid. In particular, upward incentive compatibility constraint may be binding at the optimum. As a consequence, they may be distortion at the top of the distribution. In addition to this, we show that the optimal solution often requires a kind of form of bundling, we explain explicitly distortions and show that it is sometimes optimal for the monopolist to only produce one good (instead of two) or to exclude some buyers from the market. Actually, this means that the monopolist cannot fully apply his monopoly power and is better off selling both goods independently.We then define all the possible solutions in the case of a quadratic cost function for a uniform

Subsidy policy and the enlargement of choice

International Nuclear Information System (INIS)

Srinivasan, Sunderasan

2009-01-01

Development is the enlargement of people's choices. Optimal subsidy policy is intended to create the right incentives for each of the value chain participants. This paper contends that the interest subsidy offered by the Indian federal Ministry of New and Renewable Energy for solar thermal systems, through mainstream banking channels is superior in intent and outcome compared to the capital subsidy as currently offered for solar PV systems, routed through government controlled delivery channels. The interest subsidy enhances innovation, improves service delivery and expands the range of product available to consumers enjoying a wide range of endowments, thus leading to more inclusive development. The simple monopoly model developed by Atkinson [Atkinson AB. Capabilities, exclusion and the supply of goods. In: Basu K, Pattanaik P, Suzumura K, editor, Choice, Welfare and Development. Oxford University Press; 1995] is applied to the context of solar home systems to demonstrate price reduction and choice expansion in a liberalized market, facilitated by an interest subsidy scheme. (author)

Distribution and migration chronology of Eastern population sandhill cranes

Science.gov (United States)

Fronczak, David L.; Andersen, David; Hanna, Everett E.; Cooper, Thomas R.

2017-01-01

The Eastern Population (EP) of greater sandhill cranes (Antigone canadensis tabida; cranes) is expanding in size and geographic range. Little information exists regarding the geographic extent of breeding, migration, and wintering ranges, migration chronology, or use of staging areas for cranes in the EP. To obtain these data, we attached solar global positioning system (GPS) platform transmitting terminals (PTTs) to 42 sandhill cranes and monitored daily locations from December 2009 through August 2014. On average, tagged cranes settled in summer areas during late‐March in Minnesota (7%), Wisconsin (29%), Michigan, USA (21%), and Ontario, Canada (38%) and arrived at their winter terminus beginning mid‐December in Indiana (15%), Kentucky (3%), Tennessee (45%), Georgia (5%), and Florida (32%). Cranes initiated spring migration beginning mid‐February to their respective summer areas on routes similar to those used during fall migration. Twenty‐five marked cranes returned to the same summer area after a second spring migration, of which 19 (76%) settled cranes in the EP, we estimated that approximately 29–31% of cranes that summered in both Wisconsin and the Lower Peninsula of Michigan were not in areas included in the survey. The information we collected on crane movements provides insight into distribution and migration chronology that will aid in assessment of the current USFWS fall survey. In addition, information on specific use sites can assist state and federal managers to identify and protect key staging and winter areas particularly during current and future recreational harvest seasons.

Migration of northern yellowstone elk: Implications of spatial structuring

Science.gov (United States)

White, P.J.; Proffitt, K.M.; Mech, L.D.; Evans, S.B.; Cunningham, J.A.; Hamlin, K.L.

2010-01-01

Migration can enhance survival and recruitment of mammals by increasing access to higher-quality forage or reducing predation risk, or both. We used telemetry locations collected from 140 adult female elk during 20002003 and 20072008 to identify factors influencing the migration of northern Yellowstone elk. Elk wintered in 2 semidistinct herd segments and migrated 10140 km to at least 12 summer areas in Yellowstone National Park (YNP) and nearby areas of Montana. Spring migrations were delayed after winters with increased snow pack, with earlier migration in years with earlier vegetation green-up. Elk wintering at lower elevations outside YNP migrated an average of 13 days earlier than elk at higher elevations. The timing of autumn migrations varied annually, but elk left their summer ranges at about the same time regardless of elevation, wolf numbers, or distance to their wintering areas. Elk monitored for multiple years typically returned to the same summer (96 fidelity, n 52) and winter (61 fidelity, n 41) ranges. Elk that wintered at lower elevations in or near the northwestern portion of the park tended to summer in the western part of YNP (56), and elk that wintered at higher elevations spent summer primarily in the eastern and northern parts of the park (82). Elk did not grossly modify their migration timing, routes, or use areas after wolf restoration. Elk mortality was low during summer and migration (8 of 225 elk-summers). However, spatial segregation and differential mortality and recruitment between herd segments on the northern winter range apparently contributed to a higher proportion of the elk population wintering outside the northwestern portion of YNP and summering in the western portion of the park. This change could shift wolf spatial dynamics more outside YNP and increase the risk of transmission of brucellosis from elk to cattle north of the park. ?? 2010 American Society of Mammalogists.

Physicians' Migration: Perceptions of Pakistani Medical Students.

Science.gov (United States)

Hossain, Nazli; Shah, Nusrat; Shah, Tahira; Lateef, Sidra Binte

2016-08-01

To study the perceptions of medical students about factors responsible for physicians'migration. Cross-sectional survey. Dow Medical College and Civil Hospital, Karachi, from April to May 2015. Aself-administered structured questionnaire was used including demographic details, attitudes about push and pull factors of migration, and reasons for migrating or not migrating abroad. Final year students and interns were included. Likert scale from 1 to 4 (1=strongly disagree to 4=strongly agree) was used to assess attitudes. Data was analyzed by SPSS version 16. Atotal of 240 medical students, mostly females (n=181, 75%) (60% final year and 40% interns), participated in the study. Majority wished to go abroad (n=127; 54%) with United States being the favourite destination (n=80; 66.1%) and internal medicine fields being the preferred choice for specialization (n=126; 54%). The major pull factors were better quality of postgraduate education abroad (n=110; 48.2%) and economic prospects (80; 35.2%); while the push factors were a weak healthcare system (n=219; 94.3%), inadequate salary structure (n=205; 88.3%), insecurity (n=219; 93.9%) and increasing religious intolerance in Pakistan (n=183; 78.5%). This survey highlights the continuing trend of physician migration from Pakistan owing to an interplay of various push and pull factors. Majority of our medical students wish to migrate, mainly due to low salaries, poor job structure, and insecurity. Urgent interventions are required to reverse this trend of medical brain-drain.

Playful Mobility Choices: Motivating informed mobility decision making by applying game mechanics

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A. Millonig

2014-10-01

Full Text Available Motivating people to change their mobility behaviour patterns towards more sustainable forms of mobility is one of the major challenges regarding climate change and quality of life. Recently, an increasing amount of attempts to use gamification for triggering such behavioural changes can be observed. However, little is known about the actual impact of using game elements. This contribution describes a concept for systematically analysing the group-specific effects of different game mechanics on mobility decision processes (e.g. mode and route choice. Based on theoretical findings concerning player types and mobility styles we developed a framework for identifying effective game mechanics motivating users to explore mobility alternatives and take more informed and more sustainable mode or route choice decisions. The results will form the basis for implementing game mechanics in mobility information services motivating users to explore unfamiliar but more sustainable mobility options.

Weather conditions associated with autumn migration by mule deer in Wyoming

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Chadwick D. Rittenhouse

2015-06-01

Full Text Available Maintaining ecological integrity necessitates a proactive approach of identifying and acquiring lands to conserve unfragmented landscapes, as well as evaluating existing mitigation strategies to increase connectivity in fragmented landscapes. The increased use of highway underpasses and overpasses to restore connectivity for wildlife species offers clear conservation benefits, yet also presents a unique opportunity to understand how weather conditions may impact movement of wildlife species. We used remote camera observations (19,480 from an existing wildlife highway underpass in Wyoming and daily meteorological observations to quantify weather conditions associated with autumn migration of mule deer in 2009 and 2010. We identified minimal daily temperature and snow depth as proximate cues associated with mule deer migration to winter range. These weather cues were consistent across does and bucks, but differed slightly by year. Additionally, extreme early season snow depth or cold temperature events appear to be associated with onset of migration. This information will assist wildlife managers and transportation officials as they plan future projects to maintain and enhance migration routes for mule deer.

Bird migration patterns in the arid southwest-Final report

Science.gov (United States)

Ruth, Janet M.; Felix, Rodney K.; Dieh, Robert H.

2010-01-01

To ensure full life-cycle conservation, we need to understand migrant behavior en route and how migrating species use stopover and migration aerohabitats. In the Southwest, birds traverse arid and mountainous landscapes in migration. Migrants are known to use riparian stopover habitats; we know less about how migrant density varies across the Southwest seasonally and annually, and how migrants use other habitat types during migratory stopover. Furthermore, we lack information about migrant flight altitudes, speeds, and directions of travel, and how these patterns vary seasonally and annually across the Southwest. Using weather surveillance radar data, we identified targets likely dominated by nocturnally migrating birds and determined their flight altitudes, speeds, directions over ground, and variations in abundance. Migrating or foraging bats likely are present across the region in some of these data, particularly in central Texas. We found that migrants flew at significantly lower altitudes and significantly higher speeds in spring than in fall. In all seasons migrants maintained seasonally appropriate directions of movement. We detected significant differences in vertical structure of migrant densities that varied both geographically within seasons and seasonally within sites. We also found that in fall there was a greater and more variable passage of migrants through the central part of the borderlands (New Mexico and west Texas); in spring there was some suggestion of greater and more variable passage of migrants in the eastern borderlands (central and south Texas). Such patterns are consistent with the existence of at least two migration systems through western North America and the use of different migration routes in spring and fall for at least some species. Using radar data and satellite land cover data, we determined the habitats with which migrants are associated during migration stopover. There were significant differences in bird densities among

Timetable-based simulation method for choice set generation in large-scale public transport networks

DEFF Research Database (Denmark)

Rasmussen, Thomas Kjær; Anderson, Marie Karen; Nielsen, Otto Anker

2016-01-01

The composition and size of the choice sets are a key for the correct estimation of and prediction by route choice models. While existing literature has posed a great deal of attention towards the generation of path choice sets for private transport problems, the same does not apply to public...... transport problems. This study proposes a timetable-based simulation method for generating path choice sets in a multimodal public transport network. Moreover, this study illustrates the feasibility of its implementation by applying the method to reproduce 5131 real-life trips in the Greater Copenhagen Area...... and to assess the choice set quality in a complex multimodal transport network. Results illustrate the applicability of the algorithm and the relevance of the utility specification chosen for the reproduction of real-life path choices. Moreover, results show that the level of stochasticity used in choice set...

Records of Migration in the Exoplanet Configurations

Science.gov (United States)

Michtchenko, Tatiana A.; Rodriguez Colucci, A.; Tadeu Dos Santos, M.

2013-05-01

Abstract (2,250 Maximum Characters): When compared to our Solar System, many exoplanet systems exhibit quite unusual planet configurations; some of these are hot Jupiters, which orbit their central stars with periods of a few days, others are resonant systems composed of two or more planets with commensurable orbital periods. It has been suggested that these configurations can be the result of a migration processes originated by tidal interactions of the planets with disks and central stars. The process known as planet migration occurs due to dissipative forces which affect the planetary semi-major axes and cause the planets to move towards to, or away from, the central star. In this talk, we present possible signatures of planet migration in the distribution of the hot Jupiters and resonant exoplanet pairs. For this task, we develop a semi-analytical model to describe the evolution of the migrating planetary pair, based on the fundamental concepts of conservative and dissipative dynamics of the three-body problem. Our approach is based on an analysis of the energy and the orbital angular momentum exchange between the two-planet system and an external medium; thus no specific kind of dissipative forces needs to be invoked. We show that, under assumption that dissipation is weak and slow, the evolutionary routes of the migrating planets are traced by the stationary solutions of the conservative problem (Birkhoff, Dynamical systems, 1966). The ultimate convergence and the evolution of the system along one of these modes of motion are determined uniquely by the condition that the dissipation rate is sufficiently smaller than the roper frequencies of the system. We show that it is possible to reassemble the starting configurations and migration history of the systems on the basis of their final states, and consequently to constrain the parameters of the physical processes involved.

ON PROBABILITY FUNCTION OF TRIP ROUTE CHOICE IN PASSENGER TRANSPORT SYSTEM OF CITIES

Directory of Open Access Journals (Sweden)

N. Nefedof

2014-02-01

Full Text Available The results of statistical processing of experimental research data in Kharkiv, aimed at determining the relation between the passenger trip choice probability and the actual vehicles waiting time at bus terminals are presented.

Customer Responses to Channel Migration Strategies Toward the E-channel

NARCIS (Netherlands)

Trampe, Debra; Konus, Umut; Verhoef, Peter C.

2014-01-01

Many firms stimulate customers to use the E-channel for services, which provokes various consumer responses to such limits on their freedom of choice. In a study on bank customers, we examine the extent of customer reactance in response to various E-channel migration strategies, the potential of

The critical role of the routing scheme in simulating peak river discharge in global hydrological models

Science.gov (United States)

Zhao, F.; Veldkamp, T.; Frieler, K.; Schewe, J.; Ostberg, S.; Willner, S. N.; Schauberger, B.; Gosling, S.; Mueller Schmied, H.; Portmann, F. T.; Leng, G.; Huang, M.; Liu, X.; Tang, Q.; Hanasaki, N.; Biemans, H.; Gerten, D.; Satoh, Y.; Pokhrel, Y. N.; Stacke, T.; Ciais, P.; Chang, J.; Ducharne, A.; Guimberteau, M.; Wada, Y.; Kim, H.; Yamazaki, D.

2017-12-01

Global hydrological models (GHMs) have been applied to assess global flood hazards, but their capacity to capture the timing and amplitude of peak river discharge—which is crucial in flood simulations—has traditionally not been the focus of examination. Here we evaluate to what degree the choice of river routing scheme affects simulations of peak discharge and may help to provide better agreement with observations. To this end we use runoff and discharge simulations of nine GHMs forced by observational climate data (1971-2010) within the ISIMIP2a project. The runoff simulations were used as input for the global river routing model CaMa-Flood. The simulated daily discharge was compared to the discharge generated by each GHM using its native river routing scheme. For each GHM both versions of simulated discharge were compared to monthly and daily discharge observations from 1701 GRDC stations as a benchmark. CaMa-Flood routing shows a general reduction of peak river discharge and a delay of about two to three weeks in its occurrence, likely induced by the buffering capacity of floodplain reservoirs. For a majority of river basins, discharge produced by CaMa-Flood resulted in a better agreement with observations. In particular, maximum daily discharge was adjusted, with a multi-model averaged reduction in bias over about 2/3 of the analysed basin area. The increase in agreement was obtained in both managed and near-natural basins. Overall, this study demonstrates the importance of routing scheme choice in peak discharge simulation, where CaMa-Flood routing accounts for floodplain storage and backwater effects that are not represented in most GHMs. Our study provides important hints that an explicit parameterisation of these processes may be essential in future impact studies.

Migration from the CIS Countries to Amur Oblast in the Context of the Synthetic Theory

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Tatiana Nikolaevna Zhuravskaya

2016-09-01

Full Text Available The article considers international migration from the CIS countries to the Amur region in 2010- 2014 in the context of the synthetic theory of international migration by D. Massey. It is shown that separate economic theories of migration cannot explain the CIS migrants’ choice of the Amur region as a destination. In particular, socio-economic indicators characterize the region as unattractive both for permanent (high mortality, low life expectancy, relatively low standard of living and labor (low GRP, specialization in primary industries, high transport costs and pay for a patent migration. The attractiveness factors of the region fit the theory of a dual labor market: the Amur region has higher wages than the countries of origin and the growing shortage of personnel. However, it is also insufficient to explain increasing migration flows from the CIS countries, which were identified on the basis of statistical data of the Federal Migration Service of the Amur region. Based on the analysis of qualitative data the author reveals the motives (economic, educational, cultural, forced, non-self-moving and channels (social networks, intermediaries, enterprises, government programs of migration. In general, the motivation and channels of migration in the case of the Amur region look quite traditional within the framework of economic theories. However, only a comprehensive consideration of all the issues allows determining regional specificity and answering the question about the destination choice. Sources of empirical data include following: series of keynote expert and biographical interviews carried out in 2014-2015, official statistical data of FSSS and FMS, as well as data from Amurstat, the FMS of the Amur region and the insurance company ‘Kolymskaya’

Larval migration in PERL chambers as an in vitro model for percutaneous infection stimulates feeding in the canine hookworm Ancylostoma caninum

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Welz Claudia

2011-01-01

Full Text Available Abstract Background Ancylostoma caninum third-stage larvae are the non-feeding infective stage of this parasite and are able to infect potential hosts via different infection routes. Since percutaneous infection is one of the most important routes and skin penetration is the first step into parasitic life, an existing in vitro model for percutaneous migration was modified and evaluated. The main parameter used to evaluate migration was the migration ratio (migrated larvae as a percentage of total number of larvae recovered. Additionally, the skin lag was calculated, expressing the percentage of larvae remaining in the skin and therefore not being recovered. Since initiation of feeding is proposed to be an important step in the transition from free-living to parasitic A. caninum larvae, feeding assays were performed with in vitro percutaneously migrated larvae. Additionally, infective larvae of A. caninum were activated via serum-stimulation and feeding behaviour was analysed and compared between percutaneously migrated and serum-stimulated larvae. Results Maximum skin migration levels of infective larvae were observed at temperatures above 32°C when larvae were placed on the epidermal side of skin for more than 12 hours. The medium beneath the skin had no effect on migration ratio, and no significant difference between the migration ratios through fresh and frozen/thawed skin was observed. Maximum feeding levels of 93.2% were observed for percutaneously migrated larvae after 48 h incubation, whereas serum-stimulated larvae reached the maximum of 91.0% feeding larvae after 24 h. Conclusions The PERL chamber system was optimised and standardised as an in vitro model for percutaneous migration. The larvae recovered after percutaneous migration showed characteristic signs of activation similar to that of serum-stimulated larvae. The observed difference in time course of resumption of feeding indicates that percutaneously migrated larvae are not

Рassenger survey on public transport in Zhitomir and evaluation of the main technical and operational parameters for the choice of city buses

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Rudzynskyi V.V.

2016-08-01

Full Text Available The parameters of the passenger movements in the direction of public transport in Zhitomir are defined and conformity assessment of technical and operational parameters of urban shuttle buses is folded. Firstly, the amount of passenger traffic affects the optimal choice of passenger vehicles and secondly, the intensity of road traffic on the streets of areas where passengers pass routes. It should also be kept in mind that passenger traffic can fluctuate significantly depending on the time of day and days of the week. But virtually all carriers can be replaced within days with rolling at a large passenger capacity, and vice versa. Therefore, the choice of one type of rolling stock, the capacity of which is set taking into account the data on hourly passenger capacity on the most loaded part of the route up to an hour "peak", or its capacity per day on the route as a whole. Thus the research work on inspection of passenger-route passenger transport, and public electric transport in Zhitomir is conducted. Primary data was estimated to select the main criteria for urban passenger bus. It was found that the buses in the "peak" hours move on passenger congestion. Preliminary conclusions and recommendations on the criteria of optimal rolling of choice for the city bus route network are provided.

Measuring Strategic Firm Interaction in Product-Quality Choices: The Case of Airline Flight Frequency

OpenAIRE

Jan K. Brueckner; Dan Luo

2013-01-01

This paper investigates strategic interaction among airlines in product-quality choices. Using an instrumental variables approach, the paper estimates flight-frequency reaction functions, which relate an airline’s frequency on a route to its own characteristics and to the frequencies of competing airlines. A positive reaction function slope is found in some cases, indicating the presence of strategic interaction in the choice of frequencies. The paper also asks whether multimarket contact g...

Modelling the secular evolution of migrating planet pairs

Science.gov (United States)

Michtchenko, T. A.; Rodríguez, A.

2011-08-01

The subject of this paper is the secular behaviour of a pair of planets evolving under dissipative forces. In particular, we investigate the case when dissipative forces affect the planetary semimajor axes and the planets move inwards/outwards the central star, in a process known as planet migration. To perform this investigation, we introduce fundamental concepts of conservative and dissipative dynamics of the three-body problem. Based on these concepts, we develop a qualitative model of the secular evolution of the migrating planetary pair. Our approach is based on the analysis of the energy and the orbital angular momentum exchange between the two-planet system and an external medium; thus no specific kind of dissipative forces is invoked. We show that, under the assumption that dissipation is weak and slow, the evolutionary routes of the migrating planets are traced by the Mode I and Mode II stationary solutions of the conservative secular problem. The ultimate convergence and the evolution of the system along one of these secular modes of motion are determined uniquely by the condition that the dissipation rate is sufficiently smaller than the proper secular frequency of the system. We show that it is possible to reassemble the starting configurations and the migration history of the systems on the basis of their final states and consequently to constrain the parameters of the physical processes involved.

Posterior migration of lumbar disc herniation - imaging dilemma due to contrast contraindication: a case report

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Fabrício Guimarães Gonçalves

2012-06-01

Full Text Available Disc herniation with posterior epidural migration is a rare and often symptomatic entity. Multiple are the natural barriers that prevent this pattern of migration. Enhanced magnetic resonance imaging is the diagnostic modality of choice in these cases. The diagnostic dilemma in this case was the contraindication to the use of contrast since the patient was known to have chronic renal failure.

Place characteristics and residential location choice among the retirement-age population.

Science.gov (United States)

Duncombe, William; Robbins, Mark; Wolf, Douglas A

2003-07-01

We investigate the association between an extensive set of location-specific factors and the propensity of retirement-age individuals to remain in, or relocate to, those locations. In particular we investigate whether state and local fiscal factors influence the migration decisions of retirees, and we study the relative importance of fiscal and other factors in these decisions. We place decisions regarding whether to move and where to locate in a single discrete-choice framework. We estimate an individual-level location-choice model by using a combination of place-characteristics data and Census county-to-county migration data for the period 1985-1990. We find that levels of tax burdens and public services can affect location decisions. Of the fiscal variables, income taxes have the largest relative effects. However, other factors, including climate, economic conditions, and population characteristics, appear to play much larger roles in migration and location decisions. Although income tax reductions might influence the location decisions of recent retirees, whether or not the economic benefits associated with these population gains outweigh the accompanying revenue losses is an important area for further research. A more cost-effective strategy may be for states to focus on marketing their amenities rather than using fiscal policy to recruit retirees.

Risk factors for venous port migration in a single institute in Taiwan.

Science.gov (United States)

Fan, Wen-Chieh; Wu, Cheng-Han; Tsai, Ming-Ju; Tsai, Ying-Ming; Chang, Hsu-Liang; Hung, Jen-Yu; Chen, Pei-Huan; Yang, Chih-Jen

2014-01-14

An implantable port device provides an easily accessible central route for long-term chemotherapy. Venous catheter migration is one of the rare complications of venous port implantation. It can lead to side effects such as pain in the neck, shoulder, or ear, venous thrombosis, and even life-threatening neurologic problems. To date, there are few published studies that discuss such complications. This retrospective study of venous port implantation in a single center, a Taiwan hospital, was conducted from January 2011 to March 2013. Venous port migration was recorded along with demographic and characteristics of the patients. Of 298 patients with an implantable import device, venous port migration had occurred in seven, an incidence rate of 2.3%. All seven were male and had received the Bard port Fr 6.6 which had smaller size than TYCO port Fr 7.5 and is made of silicon. Significantly, migration occurred in male patients (P = 0.0006) and in those with lung cancer (P = 0.004). Multivariable logistic regression analysis revealed that lung cancer was a significant risk factor for port migration (odds ratio: 11.59; P = 0.0059). The migration rate of the Bard port Fr 6.6 was 6.7%. The median time between initial venous port implantation and port migration was 35.4 days (range, 7 to 135 days) and 71.4% (5/7) of patients had port migration within 30 days after initial port implantation. Male sex and lung cancer are risk factors for venous port migration. The type of venous port is also an important risk factor.

Dealing with the white death: avalanche risk management for traffic routes.

Science.gov (United States)

Rheinberger, Christoph M; Bründl, Michael; Rhyner, Jakob

2009-01-01

This article discusses mitigation strategies to protect traffic routes from snow avalanches. Up to now, mitigation of snow avalanches on many roads and railways in the Alps has relied on avalanche sheds, which require large initial investments resulting in high opportunity costs. Therefore, avalanche risk managers have increasingly adopted organizational mitigation measures such as warning systems and closure policies instead. The effectiveness of these measures is, however, greatly dependent on human decisions. In this article, we present a method for optimizing avalanche mitigation for traffic routes in terms of both their risk reduction impact and their net benefit to society. First, we introduce a generic framework for assessing avalanche risk and for quantifying the impact of mitigation. This allows for sound cost-benefit comparisons between alternative mitigation strategies. Second, we illustrate the framework with a case study from Switzerland. Our findings suggest that site-specific characteristics of avalanche paths, as well as the economic importance of a traffic route, are decisive for the choice of optimal mitigation strategies. On routes endangered by few avalanche paths with frequent avalanche occurrences, structural measures are most efficient, whereas reliance on organizational mitigation is often the most appropriate strategy on routes endangered by many paths with infrequent or fuzzy avalanche risk. Finally, keeping a traffic route open may be very important for tourism or the transport industry. Hence, local economic value may promote the use of a hybrid strategy that combines organizational and structural measures to optimize the resource allocation of avalanche risk mitigation.

Joint modeling of constrained path enumeration and path choice behavior: a semi-compensatory approach

DEFF Research Database (Denmark)

Kaplan, Sigal; Prato, Carlo Giacomo

2010-01-01

A behavioural and a modelling framework are proposed for representing route choice from a path set that satisfies travellers’ spatiotemporal constraints. Within the proposed framework, travellers’ master sets are constructed by path generation, consideration sets are delimited according to spatio...

Geolocator Data Reveal the Migration Route and Wintering Location of a Caribbean Martin (Progne dominicensis)

NARCIS (Netherlands)

Perlut, N.G.; Klak, T.C.; Rakhimberdiev, E.

2017-01-01

Caribbean Martins (Progne dominicensis)are common breeders on most Caribbean islands, where theyregularly roost and nest in urban areas from Februarythrough August. However, from September through January,the basic ecology of this species—its migration andwintering locations—are largely unknown. In

Routing Service Quality—Local Driver Behavior Versus Routing Services

DEFF Research Database (Denmark)

Ceikute, Vaida; Jensen, Christian S.

2013-01-01

of the quality of one kind of location-based service, namely routing services. Specifically, the paper presents a framework that enables the comparison of the routes provided by routing services with the actual driving behaviors of local drivers. Comparisons include route length, travel time, and also route...... popularity, which are enabled by common driving behaviors found in available trajectory data. The ability to evaluate the quality of routing services enables service providers to improve the quality of their services and enables users to identify the services that best serve their needs. The paper covers......Mobile location-based services is a very successful class of services that are being used frequently by users with GPS-enabled mobile devices such as smartphones. This paper presents a study of how to exploit GPS trajectory data, which is available in increasing volumes, for the assessment...

Quantitative elastic migration. Applications to 3D borehole seismic surveys; Migration elastique quantitative. Applications a la sismique de puits 3D

Energy Technology Data Exchange (ETDEWEB)

Clochard, V.

1998-12-02

3D VSP imaging is nowadays a strategic requirement by petroleum companies. It is used to precise in details the geology close to the well. Because of the lack of redundancy and limited coverage in the data. this kind of technology is more restrictive than surface seismic which allows an investigation at a higher scale. Our contribution was to develop an elastic quantitative imagine (GRT migration) which can be applied to 3 components borehole dataset. The method is similar to the Kirchhoff migration using sophistical weighting of the seismic amplitudes. In reality. GRT migration uses pre-calculated Green functions (travel time. amplitude. polarization). The maps are obtained by 3D ray tracing (wavefront construction) in the velocity model. The migration algorithm works with elementary and independent tasks. which is useful to process different kind of dataset (fixed or moving geophone antenna). The study has been followed with validations using asymptotic analytical solution. The ability of reconstruction in 3D borehole survey has been tested in the Overthrust synthetic model. The application to a real circular 3D VSP shows various problems like velocity model building, anisotropy factor and the preprocessing (deconvolution. wave mode separation) which can destroy seismic amplitudes. An isotropic 3 components preprocessing of the whole dataset allows a better lateral reconstruction. The choice of a big migration aperture can help the reconstruction of strong geological dip in spite of migration smiles. Finally, the methodology can be applied to PS converted waves. (author)

The commercialization of migration.

Science.gov (United States)

Abrera-mangahas, M A

1989-01-01

International migration is not new to the Philippines. In the recent outflow of contract workers to the Middle East, there is a shift from individual and family initiated migrations to the more organized, highly commercial variety. While profit-taking intermediaries have played some role in the past, the increase in the number and influence of these intermediaries has altered the story of migration decision-making. In 1975, the signing of the bilateral labor agreement between the governments of Iran and the Philippines signalled the rising demand for Filipino contract workers. From 1970 to 1975, the number of Asian migrant workers in the Gulf countries rose from about 120,000 to 370,000. These figures rose dramatically to 3.3 million in 1985. The growing share of organized and commercialized migration has altered migration decision making. Primarily, intermediaries are able to broaden access to foreign job and high wage opportunities. Commercialization effectively raises the transaction costs for contract migration. Studies on recruitment costs and fees show that self-solicited foreign employment costs less than employment obtained through recruitment agents and intermediaries. The difference in the 2 prices is due, not only to overhead costs of intermediation, but more importantly to the rent exacted by agents from having job information and placement rights. In the Philippines in October 1987 the average placement fee was P8000, greatly exceeding the mandated maximum fee level of P5000. This average is understated because the computation includes the 17% who do not pay any fees. The widespread and popular view of recruitment intermediaries is negative, dominated by images of abuses and victims. Private intermediaries and the government bureaucracy need each other. Intermediaries need government; their consistent demand for incentives and protection is indicative. On the other hand, government expands its supervision of control of overseas employment via the

Design and Analysis of Schemes for Adapting Migration Intervals in Parallel Evolutionary Algorithms.

Science.gov (United States)

Mambrini, Andrea; Sudholt, Dirk

2015-01-01

The migration interval is one of the fundamental parameters governing the dynamic behaviour of island models. Yet, there is little understanding on how this parameter affects performance, and how to optimally set it given a problem in hand. We propose schemes for adapting the migration interval according to whether fitness improvements have been found. As long as no improvement is found, the migration interval is increased to minimise communication. Once the best fitness has improved, the migration interval is decreased to spread new best solutions more quickly. We provide a method for obtaining upper bounds on the expected running time and the communication effort, defined as the expected number of migrants sent. Example applications of this method to common example functions show that our adaptive schemes are able to compete with, or even outperform, the optimal fixed choice of the migration interval, with regard to running time and communication effort.

The Far East taiga forest: unrecognized inhospitable terrain for migrating Arctic-nesting waterbirds?

Directory of Open Access Journals (Sweden)

Xin Wang

2018-02-01

Full Text Available The degree of inhospitable terrain encountered by migrating birds can dramatically affect migration strategies and their evolution as well as influence the way we develop our contemporary flyway conservation responses to protect them. We used telemetry data from 44 tagged individuals of four large-bodied, Arctic breeding waterbird species (two geese, a swan and one crane species to show for the first time that these birds fly non-stop over the Far East taiga forest, despite their differing ecologies and migration routes. This implies a lack of suitable taiga refuelling habitats for these long-distance migrants. These results underline the extreme importance of northeast China spring staging habitats and of Arctic areas prior to departure in autumn to enable birds to clear this inhospitable biome, confirming the need for adequate site safeguard to protect these populations throughout their annual cycle.

The Electric Fleet Size and Mix Vehicle Routing Problem with Time Windows and Recharging Stations

DEFF Research Database (Denmark)

Hiermann, Gerhard; Puchinger, Jakob; Røpke, Stefan

2016-01-01

Due to new regulations and further technological progress in the field of electric vehicles, the research community faces the new challenge of incorporating the electric energy based restrictions into vehicle routing problems. One of these restrictions is the limited battery capacity which makes...... detours to recharging stations necessary, thus requiring efficient tour planning mechanisms in order to sustain the competitiveness of electric vehicles compared to conventional vehicles. We introduce the Electric Fleet Size and Mix Vehicle Routing Problem with Time Windows and Recharging Stations (E......-FSMFTW) to model decisions to be made with regards to fleet composition and the actual vehicle routes including the choice of recharging times and locations. The available vehicle types differ in their transport capacity, battery size and acquisition cost. Furthermore, we consider time windows at customer...

First insights into the migration route and migratory connectivity of the Paddyfield Warbler using geolocator tagging and stable isotope analysis

Czech Academy of Sciences Publication Activity Database

Brlík, Vojtěch; Ilieva, M.; Lisovski, S.; Voigt, C. C.; Procházka, Petr

(2018) ISSN 0021-8375 R&D Projects: GA ČR GA13-06451S Institutional support: RVO:68081766 Keywords : Bird migration * Indo-European flyway * Light-level geolocation * Migration direction Impact factor: 1.468, year: 2016

Pre-spawning migration of adult Pacific lamprey, Entosphenus tridentatus, in the Willamette River, Oregon, U.S.A.

Science.gov (United States)

Clemens, Benjamin J.; Mesa, Matthew G.; Magie, Robert J.; Young, Douglas A.; Schreck, Carl B.

2012-01-01

We describe the migration distances and timing of the adult Pacific lamprey, Entosphenus tridentatus, in the Willamette River Basin (Oregon, U.S.A.). We conducted aerial surveys to track radio-tagged fish upstream of a major waterfall and hydropower complex en route to spawning areas. We detected 24 out of the 43 fish that passed the waterfall-hydropower complex. Of the detected fish, 17 were detected multiple times. Their maximum migration distance upstream in the mainstem Willamette approximated a normal distribution. The maximum distance migrated upstream did not significantly correlate with total body length (r = −0.186, P = 0.385) or date that the fish passed Willamette Falls (r = −0.118, P = 0.582). Fish migrated primarily during the spring to early summer period before stopping during the summer, when peak river temperatures (≥20°C). However, at least three fish continued to migrate upstream after September. Behavior ranged from relatively slow migration, followed by holding; to rapid migration, followed by slow migration further up in the basin. This study provides a basis for informing more detailed research on Pacific lamprey in the future.

Memory, not just perception, plays an important role in terrestrial mammalian migration.

Science.gov (United States)

Bracis, Chloe; Mueller, Thomas

2017-05-31

One of the key questions regarding the underlying mechanisms of mammalian land migrations is how animals select where to go. Most studies assume perception of resources as the navigational mechanism. The possible role of memory that would allow forecasting conditions at distant locations and times based on information about environmental conditions from previous years has been little studied. We study migrating zebra in Botswana using an individual-based simulation model, where perceptually guided individuals use currently sensed resources at different perceptual ranges, while memory-guided individuals use long-term averages of past resources to forecast future conditions. We compare simulated individuals guided by perception or memory on resource landscapes of remotely sensed vegetation data to trajectories of GPS-tagged zebras. Our results show that memory provides a clear signal that best directs migrants to their destination compared to perception at even the largest perceptual ranges. Zebras modelled with memory arrived two to four times, or up to 100 km, closer to the migration destination than those using perception. We suggest that memory in addition to perception is important for directing ungulate migration. Furthermore, our findings are important for the conservation of migratory mammals, as memory informing direction suggests migration routes could be relatively inflexible. © 2017 The Author(s).

Competition, predation, and migration : Individual choice patterns of Serengeti migrants captured by hierarchical models

NARCIS (Netherlands)

Hopcraft, J. Grant C.; Morales, J. M.; Beyer, H. L.; Borner, Markus; Mwangomo, Ephraim; Sinclair, A. R. E.; Olff, Han; Haydon, Daniel T.

Large-herbivore migrations occur across gradients of food quality or food abundance that are generally determined by underlying geographic patterns in rainfall, elevation, or latitude, in turn causing variation in the degree of interspecific competition and the exposure to predators. However, the

E-cadherin is required for cranial neural crest migration in Xenopus laevis.

Science.gov (United States)

Huang, Chaolie; Kratzer, Marie-Claire; Wedlich, Doris; Kashef, Jubin

2016-03-15

The cranial neural crest (CNC) is a highly motile and multipotent embryonic cell population, which migrates directionally on defined routes throughout the embryo, contributing to facial structures including cartilage, bone and ganglia. Cadherin-mediated cell-cell adhesion is known to play a crucial role in the directional migration of CNC cells. However, migrating CNC co-express different cadherin subtypes, and their individual roles have yet to be fully explored. In previous studies, the expression of individual cadherin subtypes has been analysed using different methods with varying sensitivities, preventing the direct comparison of expression levels. Here, we provide the first comprehensive and comparative analysis of the expression of six cadherin superfamily members during different phases of CNC cell migration in Xenopus. By applying a quantitative RT-qPCR approach, we can determine the copy number and abundance of each expressed cadherin through different phases of CNC migration. Using this approach, we show for the first time expression of E-cadherin and XB/C-cadherin in CNC cells, adding them as two new members of cadherins co-expressed during CNC migration. Cadherin co-expression during CNC migration in Xenopus, in particular the constant expression of E-cadherin, contradicts the classical epithelial-mesenchymal transition (EMT) model postulating a switch in cadherin expression. Loss-of-function experiments further show that E-cadherin is required for proper CNC cell migration in vivo and also for cell protrusion formation in vitro. Knockdown of E-cadherin is not rescued by co-injection of other classical cadherins, pointing to a specific function of E-cadherin in mediating CNC cell migration. Finally, through reconstitution experiments with different E-cadherin deletion mutants in E-cadherin morphant embryos, we demonstrate that the extracellular domain, but not the cytoplasmic domain, of E-cadherin is sufficient to rescue CNC cell migration in vivo

State alternative route designations

International Nuclear Information System (INIS)

1989-07-01

Pursuant to the Hazardous Materials Transportation Act (HMTA), the Department of Transportation (DOT) has promulgated a comprehensive set of regulations regarding the highway transportation of high-level radioactive materials. These regulations, under HM-164 and HM-164A, establish interstate highways as the preferred routes for the transportation of radioactive materials within and through the states. The regulations also provide a methodology by which a state may select alternative routes. First,the state must establish a ''state routing agency,'' defined as an entity authorized to use the state legal process to impose routing requirements on carriers of radioactive material (49 CFR 171.8). Once identified, the state routing agency must select routes in accordance with Large Quantity Shipments of Radioactive Materials or an equivalent routing analysis. Adjoining states and localities should be consulted on the impact of proposed alternative routes as a prerequisite of final route selection. Lastly, the states must provide written notice of DOT of any alternative route designation before the routes are deemed effective

Evaluation of the Safe Routes to Transit Program in CaliforniaÂ

OpenAIRE

Weinzimmer, David; Sanders, Rebecca L.; Dittrich, Heidi; Cooper, Jill F.

2014-01-01

This paper elaborates on findings from an evaluation of the San Francisco Bay Area’s Safe Routes to Transit (SR2T) program, which funded enhancements to increase walking and cycling to regional transit stations. To understand how the program influenced travel choices, behavior, and perceptions of safety and local air quality, researchers surveyed transit users and observed driver, pedestrian, and bicyclist behavior in the periods before and after the enhancements were made at multiple trans...

Hurricane Evacuation Routes

Data.gov (United States)

Department of Homeland Security — Hurricane Evacuation Routes in the United States A hurricane evacuation route is a designated route used to direct traffic inland in case of a hurricane threat. This...

Will They Stay? Foreign-Born Out-Migration from New U.S. Destinations

Science.gov (United States)

Gurak, Douglas T.; Lee, Min-Ah

2012-01-01

Immigrants living in new destinations in 1995 were 2.5 times more likely to have migrated to another labor market by 2000 as immigrants living in traditional places. The researchers look at two competing explanations for immigrants’ differential internal migration patterns, namely that immigrants prefer areas with relatively large nativity concentrations which provide them with social support versus immigrants are target earners who prefer robust labor markets with strong employment growth and high wages. Utilizing confidential Census data for 1990 and 2000, the authors develop new destination classifications for 741 labor markets that take into account the differential growth and composition characteristics of 24 Asian, Latin American and Caribbean immigrant groups living in those markets. The empirical analysis of labor market out-migration indicates that immigrants do not see internal migration as an either/or choice between economics and social support but prefer residence places that allow them to maximize both conditions. PMID:22923857

Relations between information and communication technologies and international migration

Directory of Open Access Journals (Sweden)

Lukić Vesna

2017-01-01

asylum seekers have recently started. That can also be said for the research, where ICTs serve for gaining knowledge on migrants and attitudes towards immigrants. Although not voluminous, academic literature on the use and implications of ICTs use in the migration process in Serbia points to greater use of ICTs by certain groups of migrants (long-term settled refugees from former Yugoslavia in relation to the local population. There are also generational and gender differences in the use of ICTs by migrants. When it comes to transit asylum seekers in Serbia, the use of ICTs at various stages of migration and for various purposes (among them are the selection of the country of destination, the route of movement, but also contact with other migrants and smugglers is observed. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III47006

Migratory routes and at-sea threats to Pink-footed Shearwaters

Science.gov (United States)

Adams, Josh; Felis, Jonathan J.; Hodum, Peter; Colodro, Valentina; Carle, Ryan; López, Verónica

2016-01-01

The Pink-footed Shearwater (Ardenna creatopus) is a seabird with a breeding range restricted to three islands in Chile and an estimated world population of approximately 56,000 breeding individuals (Muñoz 2011, Oikonos unpublished data). Due to multiple threats on breeding colonies and at-sea, Pink-footed Shearwaters are listed as Endangered by the government of Chile (Reglamento de Clasificación de Especies, 2011), Threatened by the government of Canada (Environment Canada 2008), and are listed under Appendix 1 of the Agreement on the Conservation of Albatrosses and Petrels (ACAP 2013). A principal conservation concern for the species is mortality from fisheries bycatch during the breeding and non-breeding seasons; thus, identification of areas of overlap between at-sea use by Pink-footed Shearwaters and fisheries is a high priority conservation objective (Hinojosa Sáez and Hodum 1997, Mangel et al. 2013, ACAP 2013). During the non-breeding period, Pink-footed Shearwaters range as far north as Canada, although little was known until recently about migration routes and important wintering areas where fisheries bycatch could be a risk. Additionally, Pink-footed Shearwaters face at-sea threats during the non-breeding season off the west coast of North America. Recently, areas used by wintering Pink-footed Shearwaters have been identified as areas of interest for developing alternative energy offshore in North America (e.g., floating wind generators; Trident Winds 2016). The goal of our study was to track Pink-footed Shearwater post-breeding movements with satellite tags to identify timing and routes of migration, locate important non-breeding foraging habitats, and determine population distribution among different wintering regions.

The Last Adventure: Retirement Migration, Climate and "Amenities"

Directory of Open Access Journals (Sweden)

Saša Božić

2001-12-01

concept is "tested" in other scales. One is e.g. the force − choice continuum considering the fact that in many cases frail health, housing and daily life costs play an important role in the decision making of the retirement migrants. Another one is the production − consumption "continuum". In both cases variations stretch the concept along the scale, proving that the retirement migration cannot be treated as a clearly bounded concept. Health, climate, amenities and other factors interfere whenever an explanation is expected to emerge from the retirement migration concept. Finally, the author admits that other concepts are not completely coherent as well, they are, however, more firmly bounded. An alternative solution would be to concentrate on characteristics that are shared by all retirement migrants: retirement (as a social position, the last phase in a (post-modem biography and common Mediterranean destinations. He suggests that researchers should focus on the actors and their endeavours to fulfil their personal utopian goals and that such a proceeding would probably give good results at this stage of the retirement migration research.

The Hem protein mediates neuronal migration by inhibiting WAVE degradation and functions opposite of Abelson tyrosine kinase

Science.gov (United States)

Zhu, Zengrong; Bhat, Krishna Moorthi

2011-01-01

In the nervous system, neurons form in different regions, then they migrate and occupy specific positions. We have previously shown that RP2/sib, a well-studied neuronal pair in the Drosophila ventral nerve cord (VNC), has a complex migration route. Here, we show that the Hem protein, via the WAVE complex, regulates migration of GMC-1 and its progeny RP2 neuron. In Hem or WAVE mutants, RP2 neuron either abnormally migrates, crossing the midline from one hemisegment to the contralateral hemisegment, or does not migrate at al and fail to send out its axon projection. We report that Hem regulates neuronal migration through stabilizing WAVE. Since Hem and WAVE normally form a complex, our data argues that in the absence of Hem, WAVE, which is presumably no longer in a complex, becomes susceptible to degradation. We also find that Abelson Tyrosine kinase affects RP2 migration in a similar manner as Hem and WAVE, and appears to operate via WAVE. However, while Abl negatively regulates the levels of WAVE, it regulates migration via regulating the activity of WAVE. Our results also show that during the degradation of WAVE, Hem function is opposite to that of and downstream of Abl. PMID:21726548

Pseudo-Cycle-Based Multicast Routing in Wormhole-Routed Networks

Institute of Scientific and Technical Information of China (English)

SONG JianPing (宋建平); HOU ZiFeng (侯紫峰); XU Ming (许铭)

2003-01-01

This paper addresses the problem of fault-tolerant multicast routing in wormholerouted multicomputers. A new pseudo-cycle-based routing method is presented for constructing deadlock-free multicast routing algorithms. With at most two virtual channels this technique can be applied to any connected networks with arbitrary topologies. Simulation results show that this technique results in negligible performance degradation even in the presence of a large number of faulty nodes.

Impact of rural urban migration on physical and social environment: The case of Dhaka city

Directory of Open Access Journals (Sweden)

Momtaz Jahan

2012-09-01

Full Text Available Rural urban migration is the principle component of rapid and unplanned growth of towns and cities in the developing countries. Gross disparities in socio-economic opportunity between urban and rural areas and frequent natural disasters in some regions encourage large flow of migrants from rural Bangladesh to the large cities. For various reasons Dhaka is an attractive destination for the rural migrants. Migration to Dhaka, the capital city of Bangladesh, is the focus of this article which identifies the factors contributing to the migration process. The impact of migration is diverse both at the urban destination and at the rural origin. At both ends there are economic, demographic, environmental and socio-cultural impacts. This paper focuses on the urban end. It examines the overall conditions of the underprivileged, poor migrants and the consequences of migration on the physical and social environment on their choice of destination.

Routing in opportunistic networks

CERN Document Server

Dhurandher, Sanjay; Anpalagan, Alagan; Vasilakos, Athanasios

2013-01-01

This book provides a comprehensive guide to selected topics, both ongoing and emerging, in routing in OppNets. The book is edited by worldwide technical leaders, prolific researchers and outstanding academics, Dr. Isaac Woungang and co-editors, Dr. Sanjay Kumar Dhurandher, Prof. Alagan Anpalagan and Prof. Athanasios Vasilakos. Consisting of contributions from well known and high profile researchers and scientists in their respective specialties, the main topics that are covered in this book include mobility and routing, social-aware routing, context-based routing, energy-aware routing, incentive-aware routing, stochastic routing, modeling of intermittent connectivity, in both infrastructure and infrastructure-less OppNets. Key Features: Discusses existing and emerging techniques for routing in infrastructure and infrastructure-less OppNets. Provides a unified covering of otherwise disperse selected topics on routing in infrastructure and infrastructure-less OppNets.  Includes a set of PowerPoint slides and g...

Radionuclide therapy: regional and systemic routes of administration

International Nuclear Information System (INIS)

Shapiro, B.

1991-01-01

The optimal sequencing and integration of radiopharmaceutical therapy with respect to the multiple and competing therapeutic modalities is examined. It is estimated that the central goal of therapeutic nuclear medicine is to increase radiopharmaceutical delivery to tumour targets while sparing sensitive normal tissues. Among the factors to be considered in the choice of therapeutic radionuclides are: the decay mode, gamma-ray yield, half-lives and chemical reactivity. Several routes of administration are discussed and a number of manipulations which may be used to further improve radioparmaceutical delivery are outlined. The difficulty to perform accurate radiation dosimetry is also briefly examined. 14 refs., 1 tab

An Examination of Visitors’ Interest in Tourist Cards and Cultural Routes in the Case of a Romanian Destination

Directory of Open Access Journals (Sweden)

Ana ISPAS

2015-10-01

Full Text Available Although tourist cards and cultural routes have been interesting innovations when they were launched on the international tourism market, they are rarely implemented in Romanian tourism destinations, especially in an integrated manner. This paper presents a theoretical model regarding the integration of tourist cards in cultural routes, based on the assumption that tourists who are interested in both products have similar demographic and travel characteristics. The research results outline only the infl uence of tourists’ travel characteristics on their interest to buy cultural routes and tourist cards. Leisure travelers should be the main targeted segment, as their probability to buy such products is higher than in the case of business or VFR (visit friends and relatives tourists. These results can assist the Destination Management Organizations (DMOs regarding the choice of marketing strategies aimed at integrating cultural routes in a tourist card.

A family of spatial interaction models incorporating information flows and choice set constraints applied to U.S. interstate labor flows.

Science.gov (United States)

Smith, T R; Slater, P B

1981-01-01

"A new family of migration models belonging to the elimination by aspects family is examined, with the spatial interaction model shown to be a special case. The models have simple forms; they incorporate information flow processes and choice set constraints; they are free of problems raised by the Luce Choice Axiom; and are capable of generating intransitive flows. Preliminary calibrations using the Continuous Work History Sample [time] series data indicate that the model fits the migration data well, while providing estimates of interstate job message flows. The preliminary calculations also indicate that care is needed in assuming that destination [attraction] are independent of origins." excerpt

Modeling the secular evolution of migrating planet pairs

Science.gov (United States)

Michtchenko, T. A.; Rodríguez, A.

2011-10-01

The secular regime of motion of multi-planetary systems is universal; in contrast with the 'accidental' resonant motion, characteristic only for specific configurations of the planets, secular motion is present everywhere in phase space, even inside the resonant region. The secular behavior of a pair of planets evolving under dissipative forces is the principal subject of this study, particularly, the case when the dissipative forces affect the planetary semi-major axes and the planets move inward/outward the central star, the process known as planet migration. Based on the fundamental concepts of conservative and dissipative dynamics of the three-body problem, we develop a qualitative model of the secular evolution of the migrating planetary pair. Our approach is based on analysis of the energy and the orbital angular momentum exchange between the two-planet system and an external medium; thus no specific kind of dissipative forces is invoked. We show that, under assumption that dissipation is weak and slow, the evolutionary routes of the migrating planets are traced by the Mode I and Mode II stationary solutions of the conservative secular problem. The ultimate convergence and the evolution of the system along one of these secular modes of motion is determined uniquely by the condition that the dissipation rate is sufficiently smaller than the proper secular frequency of the system. We show that it is possible to reassemble the starting configurations and migration history of the systems on the basis of their final states and consequently to constrain the parameters of the physical processes involved.

Effect of Migration Pathway on Travel Time and Survival of Acoustic-Tagged Juvenile Salmonids in the Columbia River Estuary

Energy Technology Data Exchange (ETDEWEB)

Harnish, Ryan A.; Johnson, Gary E.; McMichael, Geoffrey A.; Hughes, Michael S.; Ebberts, Blaine D.

2012-02-01

Off-channel areas (side channels, tidal flats, sand bars, and shallow-water bays) may serve as important migration corridors through estuarine environments for salmon and steelhead smolts. Relatively large percentages (21-33%) of acoustic-tagged yearling and subyearling Chinook salmon and steelhead smolts were detected migrating through off-channel areas of the Columbia River estuary in 2008. The probability of survival for off-channel migrants (0.78-0.94) was similar to or greater than the survival probability of main channel migrants (0.67-0.93). Median travel times were similar for all species or run types and migration pathways we examined, ranging from 1-2 d. The route used by smolts to migrate through the estuary may affect their vulnerability to predation. Acoustic-tagged steelhead that migrated nearest to avian predator nesting colonies experienced higher predation rates (24%) than those that migrated farthest from the colonies (10%). The use of multiple migration pathways may be advantageous to out-migrating smolts because it helps to buffer against high rates of mortality, which may occur in localized areas, and helps to minimize inter- and intraspecific competition.

Factors Affecting Route Selection and Survival of Steelhead Kelts at Snake River Dams in 2012 and 2013

Energy Technology Data Exchange (ETDEWEB)

Harnish, Ryan A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Colotelo, Alison HA [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Li, Xinya [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ham, Kenneth D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Deng, Zhiqun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2014-12-01

In 2012 and 2013, Pacific Northwest National Laboratory conducted a study that summarized the passage proportions and route-specific survival rates of steelhead kelts that passed through Federal Columbia River Power System (FCRPS) dams. To accomplish this, a total of 811 steelhead kelts were tagged with Juvenile Salmon Acoustic Telemetry System (JSATS) transmitters. Acoustic receivers, both autonomous and cabled, were deployed throughout the FCRPS to monitor the downstream movements of tagged-kelts. Kelts were also tagged with Passive Integrated Transponder tags to monitor passage through juvenile bypass systems and detect returning fish. The current study evaluated data collected in 2012 and 2013 to identify individual, behavioral, environmental and dam operation variables that were related to passage and survival of steelhead kelts that passed through FCRPS dams. Bayesian model averaging of multivariable logistic regression models was used to identify the environmental, temporal, operational, individual, and behavioral variables that had the highest probability of influencing the route of passage and the route-specific survival probabilities for kelts that passed Lower Granite (LGR), Little Goose (LGS), and Lower Monumental (LMN) dams in 2012 and 2013. The posterior probabilities of the best models for predicting route of passage ranged from 0.106 for traditional spill at LMN to 0.720 for turbine passage at LGS. Generally, the behavior (depth and near-dam searching activity) of kelts in the forebay appeared to have the greatest influence on their route of passage. Shallower-migrating kelts had a higher probability of passing via the weir and deeper-migrating kelts had a higher probability of passing via the JBS and turbines than other routes. Kelts that displayed a higher level of near-dam searching activity had a higher probability of passing via the spillway weir and those that did less near-dam searching had a higher probability of passing via the JBS and

Role of Travel Time Information on Day-to-Day Route Choice Behavior Based on Real-World Experiments

NARCIS (Netherlands)

van Essen, Mariska; Thomas, Tom; Chorus, Caspar; van Berkum, Eric C.

2016-01-01

It is widely believed that travel time information leads to reductions in traffic congestion and thereby improves network efficiency. An important research topic within travel behavior research is therefore how car drivers choose their routes, specifically when they receive travel time information.

Planning routes around the world: International evidence for southern route preferences

NARCIS (Netherlands)

Brunyé, Tad T.; Andonova, Elena; Meneghetti, Chiara; Noordzij, Matthijs Leendert; Pazzaglia, Francesca; Wienemann, Rasmus; Mahoney, Caroline R.; Taylor, Holly A.

2012-01-01

Three studies test whether the southern route preference, which describes the tendency for route planners to disproportionately select south- rather than north-going routes, can be attributed to regional elevation patterns; specifically, we ask whether this effect replicates in three topographically

A preliminary study of international migration of the Chinese people.

Science.gov (United States)

Zhu, G

1994-01-01

International Chinese migration has spanned five periods: 1) an initial period of random and short-term migration dating back to the Qing and Han dynasties; 2) a spontaneous period since the Sui and Tang dynasties along trade routes; 3) a transition period during the Ming dynasty and the early Qing dynasty with war, poverty, and population growth as push factors; 4) peak migration during the Opium War period due to economic depression, population pressure, and the "coolie" trade; and 5) continuous development between the 1920s and 1949. Migration tended to occur between Guangdong and Fujian provinces and other southeast Asian countries. Four factors were identified as necessary for international migration to occur: the origin of migration, the destination factor, the middle link factor, and the immigrant characteristics. The origins of early Chinese migration appeared in a country of political corruption, population pressure, a backward economy, and social chaos. The pull factors at destination end were demand for labor. The middle link was the short distance between Guangdong and Fujian provinces and southeast Asian countries and longstanding nongovernmental exchanges. Other links were the similarity of climate, similar racial features, cultural lifestyle similarities, and convenient transportation. The people in these two provinces had a history of migration and a personality suitable for the spirit of adventure. Peak migration occurred during the late Qing dynasty and during the continuous development period. Between 1840 and 1911 there were about 10 million Chinese immigrants and during 1911 and 1949 there were about 6 million. In general, over 20 million immigrated prior to 1949, of which about 50% migrated during the peak period, 33% during the continuous period, and 20% before 1840. This amounted to about 33% of European migration and two times African migration. 60% were from Guangdong, and 30% were from Fujian province, of whom most were from counties

Routes into the Mainstream: Career Choices of Women and Minorities. Occasional Paper No. 124.

Science.gov (United States)

Berryman, Sue E.

Joint implications from five recent studies on occupational choice indicate that a more in-depth concentration on the occupational consistency or discontinuity of women and minorities will provide direction for future academic discipline and policy for this population. The discipline and policy process is potentially one of the most important…

Risk factors for venous port migration in a single institute in Taiwan

OpenAIRE

Fan, Wen-Chieh; Wu, Cheng-Han; Tsai, Ming-Ju; Tsai, Ying-Ming; Chang, Hsu-Liang; Hung, Jen-Yu; Chen, Pei-Huan; Yang, Chih-Jen

2014-01-01

Background An implantable port device provides an easily accessible central route for long-term chemotherapy. Venous catheter migration is one of the rare complications of venous port implantation. It can lead to side effects such as pain in the neck, shoulder, or ear, venous thrombosis, and even life-threatening neurologic problems. To date, there are few published studies that discuss such complications. Methods This retrospective study of venous port implantation in a single center, a Taiw...

Proposals for the Negotiation Process on the United Nations Global Compact for Migration

Directory of Open Access Journals (Sweden)

Victor Genina

2017-09-01

• builds a cooperation-oriented, peer-review mechanism to review migration policies.    The paper has been conceived as an input for those who will take part in the negotiation of the global compact for migration, as well as those who will closely follow those negotiations. Thus, the paper assumes a level of knowledge on how international migration has been addressed within the United Nations during the last several years and of the complexities of these negotiation processes. The author took part in different UN negotiation processes on international migration from 2004 to 2013. The paper is primarily based on this experience.[4] [1] G.A. Res. 71/1, ¶ 21 (Sept. 19, 2016. [2] G.A. Res. 68/4 (Oct. 3, 2013. [3] A mixed flow, according to UNHCR (n.d., is the migratory flow comprised by both asylum seekers and migrants: “Migrants and refugees increasingly make use of the same routes and means of transport to get to an overseas destination.” [4] During that period, the author was a staff member of the Mexican delegation to the United Nations, both in Geneva and New York.

Lifestyle mobilities: The crossroads of travel, leisure and migration

OpenAIRE

Cohen, Scott; Duncan, T; Thulemark, M

2013-01-01

This article examines how the mobilities paradigm intersects with physically moving as an on-going lifestyle choice. We conceptualise a lens of ‘lifestyle mobilities’ that challenges discrete notions of, and allows for a wider grasp of the increasing fluidity between travel, leisure and migration. We demonstrate how contemporary lifestyle-led mobility patterns contribute to and illustrate a breakdown in conventional binary divides between work and leisure, and a destabilisation of concepts of...

Migration modelling in the New Economic Geography

OpenAIRE

Camacho Pérez, Maria del Carmen

2010-01-01

The benchmark of this paper is the Fujita and Thisse (2002) core-periphery model, which adds a R&D sector with skilled labor to create new varieties for the modern sector. The number of R&D firms increases not only with the number of existing patents and knowledge spillovers but also with the number of skilled workers who can migrate and choose theregion offering the better lifetime salary.The main objective of the present work is to analyse the long-term consequences of the choice of the mig...

Signature of charge migration in modulations of double ionization

Science.gov (United States)

Mauger, François; Abanador, Paul M.; Bruner, Adam; Sissay, Adonay; Gaarde, Mette B.; Lopata, Kenneth; Schafer, Kenneth J.

2018-04-01

We present a theoretical investigation of charge migration following strong-field ionization in a multielectron system. We study a model homonuclear molecule with two electrons, each restricted to one dimension (1 +1 D ), interacting with a strong, static electric field. We show that in this system charge migration results from the interplay between multiple ionization channels that overlap in space, creating a coherent electron-hole wave packet in the cation. We also find that, in our case, charge migration following the first ionization manifests as a modulation of the subsequent double-ionization signal. We derive a parametrized semiclassical model from the full multielectron system and we discuss the importance of the choice of cation electronic-structure basis for the efficacy of the semiclassical representation. We use the ab initio solution of the full 1 +1 D system as a reference for the qualitative and quantitative results of the parametrized semiclassical model. We discuss the extension of our model to long-wavelength time-dependent fields with full-dimension, many-electron targets.

Disentangling migratory routes and wintering grounds of Iberian near-threatened European Rollers Coracias garrulus.

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Juan Rodríguez-Ruiz

Full Text Available Long-distance migrants are suffering drastic declines in the last decades. Causes beneath this problem are complex due to the wide spatial and temporal scale involved. We aim to reveal migratory routes, stopover areas, wintering grounds, and migratory strategies for the most southwestern populations of the near-threatened European Roller Coracias garrulus in order to identify conservation key areas for the non-breeding stage of this species. To this end, we used tracking data from seven satellite transmitters fitted to birds breeding in different populations throughout the Iberian Peninsula and four geolocators fitted to individuals in a southeastern Iberian population. Precise satellite data were used to describe daily activity patterns and speed in relation to the main regions crossed during the migration. Individuals from the most southwestern Iberian populations made a detour towards the Atlantic African coast whereas those from northeastern populations followed a straight north-to-south route. We identified important stopover areas in the Sahel belt, mainly in the surroundings of the Lake Chad, and wintering grounds on southwestern Africa farther west than previously reported for the species. Concerning the migratory strategy, satellite data revealed: 1 a mainly nocturnal flying activity, 2 that migration speed depended on the type of crossed habitat, with higher average speed while crossing the desert; and 3 that the migration was slower and lasted longer in autumn than in spring. The studied populations showed weak migratory connectivity, suggesting the confluence of birds from a wide range of breeding grounds in a restricted wintering area. Therefore, we suggest to target on defining precisely key areas for this species and identifying specific threats in them in order to develop an appropriate global conservation programme for the European Roller.

Route-Over Forwarding Techniques in a 6LoWPAN

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Andreas Weigel

2014-12-01

Full Text Available 6LoWPAN plays a major role within the protocol stack for the future Internet of Things. Its fragmentation mechanism enables transport of IPv6 datagrams with the required minimum MTU of 1280 bytes over 802.15.4-based networks. With the goal of a fully standardized WSN protocol stack currently necessitating a route-over approach, i.e., routing at the IP-layer, there are two main choices for any 6LoWPAN implementation with regard to datagram fragmentation: Hop-by-hop assembly or a cross-layered direct mode, which forwards individual 6LoWPAN fragments before the whole datagram has arrived. In addition to these two straightforward approaches, we propose enhancements based on adaptive rate-restriction for the direct forwarding and a retry control for both modes to reduce the number of losses of larger datagrams. An evaluation of these modes in a simulation environment and a hardware testbed indicate that the proposed enhancements can considerably improve PRR and latency within 6LoWPAN networks.

Migration of Gelfoam to the gallbladder after liver biopsy

Energy Technology Data Exchange (ETDEWEB)

Riddle, Chris [The Hospital for Sick Children, Image Guided Therapy, Department of Diagnostic Imaging, Toronto (Canada); Dalhousie University, School of Medicine, Halifax (Canada); Ahmed, Bilal [University of Toronto School of Medicine, Toronto (Canada); Doyle, John [The Hospital for Sick Children, Department of Hematology/Oncology, Toronto (Canada); Connolly, Bairbre L. [The Hospital for Sick Children, Image Guided Therapy, Department of Diagnostic Imaging, Toronto (Canada)

2008-07-15

Liver biopsy is a common procedure, with an inherent risk of bleeding. There are different ways to help avoid hemorrhage, including biopsy through a transjugular venous route or embolization of the tract with liquid or solid materials. We describe an image-guided percutaneous core needle liver biopsy with tract embolization using thick Gelfoam slurry in a pediatric oncology patient. Imaging studies acquired after the biopsy indicated that the Gelfoam mixture had likely migrated to the gallbladder and common bile duct. We report this rare occurrence with its striking imaging in order to make those performing biopsies aware of this possibility. (orig.)

Understanding the Impact of Environmental Variability on Anchovy Overwintering Migration in the Black Sea and its Implications for the Fishing Industry

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Ceren Guraslan

2017-08-01

Full Text Available Black Sea anchovy (Engraulis encrasicolus undertake extensive overwintering migrations every fall from nursery grounds to warmer overwintering areas located on the south-eastern coast of the Black Sea. During migration and particularly upon arrival at the Anatolian coast, they support an important fishery and valuable source of income for the regional community. Black Sea anchovy have undergone significant stock fluctuations partly related to climatic conditions; for example, migrating anchovy schools arrived late or failed to arrive at the Anatolian coast when fall temperatures increased. It is therefore of importance to understand the conditions required for successful overwintering migration and explore different migration routes. This study invokes a Lagrangian modeling approach applied to satellite derived circulation and temperature data as a first attempt to model anchovy migration dynamics in the Black Sea. This modeling approach takes the influence of the physical environment into account, while the quality of overwintering grounds, adaptive, schooling, and homing behavior is neglected. The model is used to investigate the possible influence of interannual and seasonal variability of temperature and surface currents, as well as the influence of migration behavior on the success of anchovy overwintering migration for both the Black Sea and Azov Sea anchovy. The results of the present work show the possibility that overwintering anchovy fished along the Turkish Eastern Anatolian coast may not exclusively originate from the northwestern shelf, but mainly from the eastern Black Sea basin. Migration pathways are identified for both Black Sea and Azov Sea anchovy, which are of importance for the national fisheries efforts of riparian countries. The modeling results are in agreement with general patterns of anchovy migration given in the literature indicating that the physical environment may be a major factor in shaping general migration

Posterior extradural migration of extruded thoracic and lumbar disc fragments: role of MRI

International Nuclear Information System (INIS)

Neugroschl, C.; Dietemann, J.L.; Kehrli, P.; Ragragui, O.; Maitrot, D.; Gigaud, M.; Manelfe, C.

1999-01-01

We report three patients with a sequestrated disc fragment posterior to the thecal sac. The affected disc was lumbar in two cases and thoracic in the third. Disc fragment migration is usually limited to the anterior extra dural space. Migration of a disc fragment behind the dural sac is seldom encountered. MRI appears to be the method of choice to make this diagnosis. The disc fragments gave low signal on T1- and slightly high signal on T2-weighted images and showed rim contrast enhancement. The differential diagnosis includes abscess, metastatic tumour and haematoma. (orig.)

Meeting Air Transportation Demand in 2025 by Using Larger Aircraft and Alternative Routing to Complement NextGen Operational Improvements

Science.gov (United States)

Smith, Jeremy C.; Guerreiro, Nelson M.; Viken, Jeffrey K.; Dollyhigh, Samuel M.; Fenbert, James W.

2010-01-01

A study was performed that investigates the use of larger aircraft and alternative routing to complement the capacity benefits expected from the Next Generation Air Transportation System (NextGen) in 2025. National Airspace System (NAS) delays for the 2025 demand projected by the Transportation Systems Analysis Models (TSAM) were assessed using NASA s Airspace Concept Evaluation System (ACES). The shift in demand from commercial airline to automobile and from one airline route to another was investigated by adding the route delays determined from the ACES simulation to the travel times used in the TSAM and re-generating new flight scenarios. The ACES simulation results from this study determined that NextGen Operational Improvements alone do not provide sufficient airport capacity to meet the projected demand for passenger air travel in 2025 without significant system delays. Using larger aircraft with more seats on high-demand routes and introducing new direct routes, where demand warrants, significantly reduces delays, complementing NextGen improvements. Another significant finding of this study is that the adaptive behavior of passengers to avoid congested airline-routes is an important factor when projecting demand for transportation systems. Passengers will choose an alternative mode of transportation or alternative airline routes to avoid congested routes, thereby reducing delays to acceptable levels for the 2025 scenario; the penalty being that alternative routes and the option to drive increases overall trip time by 0.4% and may be less convenient than the first-choice route.

Transportation routing analysis geographic information system -- TRAGIS, a multimodal transportation routing tool

International Nuclear Information System (INIS)

Johnson, P.E.

1995-01-01

Over 15 years ago, Oak Ridge National Laboratory (ORNL) developed two transportation routing models: HIGHWAY, which predicts truck transportation routes, and INTERLINE, which predicts rail transportation routes. Subsequent modifications have been made to enhance each of these models. Some of these changes include population density information for routes, HM-164 routing regulations for highway route controlled quantities of radioactive materials (RAM) truck shipments, and inclusion of waterway routing into INTERLINE. The AIRPORT model, developed 2 years after the HIGHWAY and INTERLINE models, serves as an emergency response tool. This model identifies the nearest airports from a designated location. Currently, the AIRPORT model is inactive. The Transportation Management Division of the US Department of Energy held a Baseline Requirements Assessment Session on the HIGHWAY, INTERLINE, and AIRPORT models in April 1994 to bring together many users of these models and other experts in the transportation routing field to discuss these models and to decide on the capabilities that needed to be added. Of the many needs discussed, the primary one was to have the network databases within a geographic information system (GIS). As a result of the Baseline Requirements Session, the development of a new GIS model has been initiated. This paper will discuss the development of the new Transportation Routing Analysis GIS (TRAGIS) model at ORNL

VINE ROUTES IN BULGARIA

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Lyuben Hristov

2015-03-01

Full Text Available The article deals with a scheme for the modern vine route in Bulgaria. Five basic vine routes and one international, between Bulgaria, Macedonia and Greece are defined. All routes consider characteristic varieties of grapes and kinds of vine products. Vine tourist products combined with visits of important natural and anthropological object are in the bases of the defined routes. The described routes are an important contribution to development of alternative tourist products in the country.

Robust against route failure using power proficient reliable routing in MANET

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M. Malathi

2018-03-01

Full Text Available The aim of this paper was to propose a novel routing protocol for Mobile Adhoc Network communication which reduces the route failure during transmission. The proposed routing protocol uses 3 salient parameters to discover the path which ensure the reliable communication. The quality of the channel, link quality and energy level of the node are the major reasons for unintentional node failure in mobile Adhoc network. So the proposed routing protocol considers these three parameters to select the best forwarder node in the path. The reliable data communication is achieved by transmitting data via path selected by the proposed routing scheme has been proven using network simulator (NS2. Keywords: Channel quality, Link quality, Mobile Adhoc Network (MANET, Residual energy

Short-term organic carbon migration from polymeric materials in contact with chlorinated drinking water.

Science.gov (United States)

Mao, Guannan; Wang, Yingying; Hammes, Frederik

2018-02-01

Polymeric materials are widely used in drinking water distribution systems. These materials could release organic carbon that supports bacterial growth. To date, the available migration assays for polymeric materials have not included the potential influence of chlorination on organic carbon migration behavior. Hence, we established a migration and growth potential protocol specifically for analysis of carbon migration from materials in contact with chlorinated drinking water. Four different materials were tested, including ethylene propylene dienemethylene (EPDM), poly-ethylene (PEX b and PEX c) and poly-butylene (PB). Chlorine consumption rates decreased gradually over time for EPDM, PEXc and PB. In contrast, no free chlorine was detected for PEXb at any time during the 7 migration cycles. Total organic carbon (TOC) and assimilable organic carbon (AOC) was evaluated in both chlorinated and non-chlorinated migrations. TOC concentrations for EPDM and PEXb in chlorinated migrations were significantly higher than non-chlorinated migrations. The AOC results showed pronounced differences among tested materials. AOC concentrations from chlorinated migration waters of EPDM and PB were higher compared to non-chlorinated migrations, whereas the opposite trend was observed for PEXb and PEXc. There was also a considerable difference between tested materials with regards to bacterial growth potential. The results revealed that the materials exposed to chlorine-influenced migration still exhibited a strong biofilm formation potential. The overall results suggested that the choice in material would make a considerable difference in chlorine consumption and carbon migration behavior in drinking water distribution systems. Copyright © 2017 Elsevier B.V. All rights reserved.

Building sustainable supply chains: consumer choice or direct management?

Energy Technology Data Exchange (ETDEWEB)

Hebditch, David; Blackmore, Emma

2012-06-15

Putting a 'carbon label' on products to show how much carbon dioxide is emitted during their production, transport and disposal has been heralded as a powerful route to sustainability within companies' supply chains. Several leading firms have joined the Carbon Trust carbon labelling scheme over the past five years, including UK-based retail giant Tesco, which as early as 2007 promised to use carbon labels on all its products. But earlier this year, the multinational said it was dropping carbon labels and instead directly managing its supply chains. Many other companies are similarly choosing direct management over consumer choice as the most effective route to emission reductions. In so doing, they are shouldering greater responsibility for the emissions and impacts of their supply chains. But environmental concerns must not be allowed to trump development needs and companies must not unfairly disadvantage smaller-scale producers in developing countries.

Parallel genetic algorithms with migration for the hybrid flow shop scheduling problem

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K. Belkadi

2006-01-01

Full Text Available This paper addresses scheduling problems in hybrid flow shop-like systems with a migration parallel genetic algorithm (PGA_MIG. This parallel genetic algorithm model allows genetic diversity by the application of selection and reproduction mechanisms nearer to nature. The space structure of the population is modified by dividing it into disjoined subpopulations. From time to time, individuals are exchanged between the different subpopulations (migration. Influence of parameters and dedicated strategies are studied. These parameters are the number of independent subpopulations, the interconnection topology between subpopulations, the choice/replacement strategy of the migrant individuals, and the migration frequency. A comparison between the sequential and parallel version of genetic algorithm (GA is provided. This comparison relates to the quality of the solution and the execution time of the two versions. The efficiency of the parallel model highly depends on the parameters and especially on the migration frequency. In the same way this parallel model gives a significant improvement of computational time if it is implemented on a parallel architecture which offers an acceptable number of processors (as many processors as subpopulations.

The paradox of Spoonbill migration : Most birds travel to where survival rates are lowest

NARCIS (Netherlands)

Lok, Tamar; Overdijk, Otto; Tinbergen, Joost M.; Piersma, Theunis

2011-01-01

Migrant birds face a choice where to spend the winter. Presumably there is a trade-off between migration distance (costs) and the quality of the wintering site (benefits). Wintering site fidelity is often high and increases with age. Hypotheses to explain such a pattern assume that wintering site

Post-breeding migration of Dutch-breeding black-tailed godwits: timing, routes, use of stopovers, and nonbreeding destinations

Science.gov (United States)

Hooijmeijer, Jos C. E. W.; Senner, Nathan R.; Tibbitts, T. Lee; Gill, Robert E.; Douglas, David C.; Bruinzeel, Leo W.; Wymenga, Eddy; Piersma, Theunis

2014-01-01

Conservation of long-distance migratory shorebirds is complex because these species use habitats spread across continents and hemispheres, making identification of critical habitats and potential bottlenecks in the annual cycle especially difficult. The population of Black-tailed Godwits that breeds in Western Europe, Limosa limosa limosa, has declined precipitously over the past few decades. Despite significant efforts to identify the root causes of this decline, much remains unclear. To better understand the migratory timing, use of stopover and nonbreeding sites, and the potential impact of breeding success on these parameters, we attached 15 Argos satellite transmitters and 10 geolocation tracking devices to adult godwits nearing completion of incubation at breeding sites in southwest Friesland, The Netherlands during the spring of 2009. We successfully tracked 16 adult godwits for their entire southward migration and two others for part of it. Three migration patterns and four regions of use were apparent. Most godwits left their breeding sites and proceeded south directly to stopover sites in the Mediterranean — e.g. Spain, Portugal, and Morocco — before flying on to non-breeding sites in West Africa. Other individuals spent the entire nonbreeding season in the Mediterranean. A third pattern included a few individuals that flew nonstop from their Dutch breeding sites to nonbreeding sites in West Africa. Tracking data from this study will be immediately useful for conservation efforts focused on preserving the dispersed network of sites used by godwits during their southward migration.

Protected areas as frontiers for human migration.

Science.gov (United States)

Zommers, Zinta; MacDonald, David W

2012-06-01

Causes of human population growth near protected areas have been much debated. We conducted 821 interviews in 16 villages around Budongo Forest Reserve, Masindi district, Uganda, to explore the causes of human migration to protected areas and to identify differences in forest use between migrant and nonmigrant communities. We asked subjects for information about birthplace, migration, household assets, household activities, and forest use. Interview subjects were categorized as nonmigrants (born in one of the interview villages), socioeconomic migrants (chose to emigrate for economic or social reasons) from within Masindi district (i.e., local migrants) and from outside the Masindi district (i.e., regional migrants), or forced migrants (i.e., refugees or internally displaced individuals who emigrated as a result of conflict, human rights abuses, or natural disaster). Only 198 respondents were born in interview villages, indicating high rates of migration between 1998 and 2008. Migrants were drawn to Budongo Forest because they thought land was available (268 individuals) or had family in the area (161 individuals). A greater number of regional migrants settled in villages near Lake Albert than did forced and local migrants. Migration category was also associated with differences in sources of livelihood. Of forced migrants 40.5% earned wages through labor, whereas 25.5% of local and 14.5% of regional migrants engaged in wage labor. Migrant groups appeared to have different effects on the environment. Of respondents that hunted, 72.7% were regional migrants. Principal component analyses indicated households of regional migrants were more likely to be associated with deforestation. Our results revealed gaps in current models of human population growth around protected areas. By highlighting the importance of social networks and livelihood choices, our results contribute to a more nuanced understanding of causes of migration and of the environmental effects of

Barriers of Culture, Networks, and Language in International Migration: A Review

Directory of Open Access Journals (Sweden)

Zhiling Wang

2018-05-01

Full Text Available Along with the increasing pace of globalization, recent decades faced a dramatically increase in international migrant flows as well. Compared to the flows of trade, capital and knowledge, we observe that contemporaneous complex institutional differences, historical backgrounds, and individuals' diverse socio-demographic characteristics make the migrant workers' choice of destination arguably much more uncontrollable. This study shows that migration is in a complex way intertwined with culture, networks and language, (i by reviewing related studies on the barriers of culture, networks and language in international labor mobility, and (ii by exploring missing gaps and prospective avenues for research. Nowadays, the migration pressure on Europe and the United states has created substantial challenges, leading to an urgent need to address the economic assimilation and social integration of migrants. Against this background, we emphasize that these non-economic factors have played an increasingly critical role in shaping international migration and its future socio-economic consequences for destination countries.

The C. elegans tailless/Tlx homolog nhr-67 regulates a stage-specific program of linker cell migration in male gonadogenesis.

Science.gov (United States)

Kato, Mihoko; Sternberg, Paul W

2009-12-01

Cell migration is a common event during organogenesis, yet little is known about how migration is temporally coordinated with organ development. We are investigating stage-specific programs of cell migration using the linker cell (LC), a migratory cell crucial for male gonadogenesis of C. elegans. During the L3 and L4 larval stages of wild-type males, the LC undergoes changes in its position along the migratory route, in transcriptional regulation of the unc-5 netrin receptor and zmp-1 zinc matrix metalloprotease, and in cell morphology. We have identified the tailless homolog nhr-67 as a cell-autonomous, stage-specific regulator of timing in LC migration programs. In nhr-67-deficient animals, each of the L3 and L4 stage changes is either severely delayed or never occurs, yet LC development before the early L3 stage or after the mid-L4 stage occurs with normal timing. We propose that there is a basal migration program utilized throughout LC migration that is modified by stage-specific regulators such as nhr-67.

Dynamic Quantification of Host Schwann Cell Migration into Peripheral Nerve Allografts

Science.gov (United States)

Whitlock, Elizabeth L.; Myckatyn, Terence M.; Tong, Alice Y.; Yee, Andrew; Yan, Ying; Magill, Christina K.; Johnson, Philip J.; Mackinnon, Susan E.

2010-01-01

Host Schwann cell (SC) migration into nerve allografts is the limiting factor in the duration of immunosuppression following peripheral nerve allotransplantation, and may be affected by different immunosuppressive regimens. Our objective was to compare SC migration patterns between clinical and experimental immunosuppression regimens both over time and at the harvest endpoint. Eighty mice that express GFP under the control of the Schwann cell specific S100 promoter were engrafted with allogeneic, nonfluorescent sciatic nerve grafts. Mice received immunosuppression with either tacrolimus (FK506), or experimental T-cell triple costimulation blockade (CSB), consisting of CTLA4-immunoglobulin fusion protein, anti-CD40 monoclonal antibody, and anti-inducible costimulator monoclonal antibody. Migration of GFP-expressing host SCs into wild-type allografts was assessed in vivo every 3 weeks until 15 weeks postoperatively, and explanted allografts were evaluated for immunohistochemical staining patterns to differentiate graft from host SCs. Immunosuppression with tacrolimus exhibited a plateau of SC migration, characterized by significant early migration (< 3 weeks) followed by a constant level of host SCs in the graft (15 weeks). At the endpoint, graft fluorescence was decreased relative to surrounding host nerve, and donor SCs persisted within the graft. CSB-treated mice displayed gradually increasing migration of host SCs into the graft, without the plateau noted in tacrolimus-treated mice, and also maintained a population of donor SCs at the 15-week endpoint. SC migration patterns are affected by immunosuppressant choice, particularly in the immediate postoperative period, and the use of a single treatment of CSB may allow for gradual population of nerve allografts with host SCs. PMID:20633557

AIRLINE ITINERARY CHOICE IN A DYNAMIC SUPPLY ENVIRONMENT: RESULTS FROM A STATED PREFERENCE SURVEY

Directory of Open Access Journals (Sweden)

Uzi Freund-Feinstei

2017-12-01

Full Text Available This paper investigates the choice of airline itineraries in dynamic settings using a tailored stated preference survey. The paper hypothesizes that airline itinerary choice is not a one-time event, but a continuous process during a certain time frame. Consumers can choose either to purchase an itinerary, deferring choice up to the end of the sales period, or completely declining the purchase. Understanding such consumers’ behavior is specifically relevant to the tourism industry, where firms are extensively utilizing internet websites to offer their products (e.g., airline tickets, hotel rooms to consumers. The paper describes the stated preference survey with real itineraries of various airlines on medium and long-haul routes. Choice sets are composed with dynamic and static variables and socio-economic variables. Questionnaires were distributed electronically among various groups of respondents, yielding a sample of 914 persons. Results show that (i itinerary choice deferring takes place, with differences between tourists and business-travelers, (ii the decision whether to defer choice is affected by dynamically changing variables and by the length of each respondent’s allocated choice period, and (iii the proposed methodology is adequate for investigating choice in dynamic settings and thus indicating its potential for further research in transportation planning and in tourism.

Climate change alters the optimal wind-dependent flight routes of an avian migrant.

Science.gov (United States)

Nourani, Elham; Yamaguchi, Noriyuki M; Higuchi, Hiroyoshi

2017-05-17

Migratory birds can be adversely affected by climate change as they encounter its geographically uneven impacts in various stages of their life cycle. While a wealth of research is devoted to the impacts of climate change on distribution range and phenology of migratory birds, the indirect effects of climate change on optimal migratory routes and flyways, through changes in air movements, are poorly understood. Here, we predict the influence of climate change on the migratory route of a long-distant migrant using an ensemble of correlative modelling approaches, and present and future atmospheric data obtained from a regional climate model. We show that changes in wind conditions by mid-century will result in a slight shift and reduction in the suitable areas for migration of the study species, the Oriental honey-buzzard, over a critical section of its autumn journey, followed by a complete loss of this section of the traditional route by late century. Our results highlight the need for investigating the consequences of climate change-induced disturbance in wind support for long-distance migratory birds, particularly species that depend on the wind to cross ecological barriers, and those that will be exposed to longer journeys due to future range shifts. © 2017 The Author(s).

Turbulence investigation and reproduction for assisting downstream migrating juvenile salmonids, Part II of II: Effects of induced turbulence on behavior of juvenile salmon, 2001-2005 final report

Science.gov (United States)

Perry, R.; Farley , M.; Hansen, G.; Morse , J.; Rondorf, D.

2005-01-01

Passage through dams is a major source of mortality of anadromous juvenile salmonids because some populations must negotiate up to eight dams in Columbia and Snake rivers. Dams cause direct mortality when fish pass through turbines, but dams may also cause indirect mortality by altering migration conditions in rivers. Forebays immediately upstream of dams have decreased the water velocity of rivers and may contribute substantially to the total migration delay of juvenile salmonids. Recently, Coutant (2001a) suggested that in addition to low water velocities, lack of natural turbulence may contribute to migration delay by causing fish to lose directional cues. Coutant (2001a) further hypothesized that restoring turbulence in dam forebays may reduce migration delay by providing directional cues that allow fish to find passage routes more quickly (Coutant 2001a). Although field experiments have yielded proof of the concept of using induced turbulence to guide fish to safe passage routes, little is known about mechanisms actually causing behavioral changes. To test hypotheses about how turbulence influences movement and behavior of migrating juvenile salmonids, we conducted two types of controlled experiments at Cowlitz Falls Dam, Washington. A common measure of migration delay is the elapsed time between arrival at, and passage through, a dam. Therefore, for the first set of experiments, we tested the effect of induced turbulence on the elapsed time needed for fish to traverse through a raceway and pass over a weir at its downstream end (time trial experiment). If turbulence helps guide fish to passage routes, then fish should pass through the raceway quicker in the presence of appropriately scaled and directed turbulent cues. Second, little is known about how the physical properties of water movement provide directional cues to migrating juvenile salmonids. To examine the feasibility of guiding fish with turbulence, we tested whether directed turbulence could guide

Route churn: an analysis of low-cost carrier route continuity in Europe

NARCIS (Netherlands)

de Wit, J.G.; Zuidberg, J.

2016-01-01

Discontinuity of air routes is a subject that has been analysed in various ways. For example, the complex network approach focuses on network robustness and resilience due to route interruptions during a relatively short period. Also seasonal interruptions of air routes are a well-documented

The paradox of extreme high-altitude migration in bar-headed geese Anser indicus

Science.gov (United States)

Hawkes, L. A.; Balachandran, S.; Batbayar, N.; Butler, P. J.; Chua, B.; Douglas, D. C.; Frappell, P. B.; Hou, Y.; Milsom, W. K.; Newman, S. H.; Prosser, D. J.; Sathiyaselvam, P.; Scott, G. R.; Takekawa, J. Y.; Natsagdorj, T.; Wikelski, M.; Witt, M. J.; Yan, B.; Bishop, C. M.

2013-01-01

Bar-headed geese are renowned for migratory flights at extremely high altitudes over the world's tallest mountains, the Himalayas, where partial pressure of oxygen is dramatically reduced while flight costs, in terms of rate of oxygen consumption, are greatly increased. Such a mismatch is paradoxical, and it is not clear why geese might fly higher than is absolutely necessary. In addition, direct empirical measurements of high-altitude flight are lacking. We test whether migrating bar-headed geese actually minimize flight altitude and make use of favourable winds to reduce flight costs. By tracking 91 geese, we show that these birds typically travel through the valleys of the Himalayas and not over the summits. We report maximum flight altitudes of 7290 m and 6540 m for southbound and northbound geese, respectively, but with 95 per cent of locations received from less than 5489 m. Geese travelled along a route that was 112 km longer than the great circle (shortest distance) route, with transit ground speeds suggesting that they rarely profited from tailwinds. Bar-headed geese from these eastern populations generally travel only as high as the terrain beneath them dictates and rarely in profitable winds. Nevertheless, their migration represents an enormous challenge in conditions where humans and other mammals are only able to operate at levels well below their sea-level maxima. PMID:23118436

Population growth and rural-urban migration, with special reference to Ghana.

Science.gov (United States)

De Graft-johnson, K T

1974-01-01

but that once people decide to migrate, they base their choice of destination primarily on economic opportunities available at that end. Distance bears little relationship to choice of destination. To stem this tide efforts need to be made to increase rural income, provide employment opportunities for those displaced as agriculture becomes more efficient, and to provide for greater amenities in rural areas. Urban unemployment is an ever-increasing problem, accentuated by population growth and migration. Intensive rural development is needed to reverse this trend.

How do en route events around the Gulf of Mexico influence landbird populations

Science.gov (United States)

Cohen, Emily B.; Barrow, Wylie C.; Buler, Jeffrey J.; Deppe, Jill L.; Farnsworth, Andrew; Marra, Peter P.; McWilliams, Scott R.; Mehlman, David W; Wilson, R. Randy; Woodrey, Mark S; Moore, Frank R.

2017-01-01

Habitats around the Gulf of Mexico (GOM) provide critical resources for Nearctic–Neotropical migratory landbirds, the majority of which travel across or around the GOM every spring and fall as they migrate between temperate breeding grounds in North America and tropical wintering grounds in the Caribbean and Central and South America. At the same time, ecosystems in the GOM are changing rapidly, with unknown consequences for migratory landbird populations, many of which are experiencing population declines. In general, the extent to which events encountered en route limit migratory bird populations is not well understood. At the same time, information from weather surveillance radar, stable isotopes, tracking, eBird, and genetic datasets is increasingly available to address many of the unanswered questions about bird populations that migrate through stopover and airspace habitats in the GOM. We review the state of the science and identify key research needs to understand the impacts of en route events around the GOM region on populations of intercontinental landbird migrants that breed in North America, including: (1) distribution, timing, and habitat associations; (2) habitat characteristics and quality; (3) migratory connectivity; and (4) threats to and current conservation status of airspace and stopover habitats. Finally, we also call for the development of unified and comprehensive long-term monitoring guidelines and international partnerships to advance our understanding of the role of habitats around the GOM in supporting migratory landbird populations moving between temperate breeding grounds and wintering grounds in Mexico, Central and South America, and the Caribbean.

Hazmat Routes (National)

Data.gov (United States)

Department of Transportation — The Federal Motor Carrier Safety Administration (FMCSA) Hazardous Material Routes (NTAD) were developed using the 2004 First Edition TIGER/Line files. The routes are...

The role of simulation in intertemporal choices

Directory of Open Access Journals (Sweden)

Garret eO'Connell

2015-03-01

Full Text Available One route to understanding the thoughts and feelings of others is by mentally putting one’s self in their shoes and seeing the world from their perspective, called simulation. Simulation is potentially used not only for inferring how others feel, but also for predicting how we ourselves will feel in the future. For instance, one might judge the worth of a future reward by simulating how much it will eventually be enjoyed. In intertemporal choices between smaller immediate and larger delayed rewards, it is observed that as the length of delay increases, delayed larger rewards lose subjective value; a phenomenon known as temporal discounting. In this article, we develop a theoretical framework for the proposition that simulation mechanisms involved in empathising with others also underlie intertemporal choices. This framework yields a testable psychological account of temporal discounting based on simulation. Such an account, if experimentally validated, could have important implications for how simulation mechanisms are investigated, and makes predictions about special populations characterised by putative deficits in simulating others.

Dynamics of career choice among students in undergraduate medical courses. A BEME systematic review : BEME Guide No. 33

NARCIS (Netherlands)

Querido, S.; Vergouw, D.; Wigersma, L.; Batenburg, R.; de Rond, M.; ten Cate, TJ

2015-01-01

Introduction: Due to the lack of a theoretically embedded overview of the recent literature on medical career decision-making, this study provides an outline of these dynamics. Since differences in educational routes to the medical degree likely affect career choice dynamics, this study focuses on

Dynamics of career choice among students in undergraduate medical courses. A BEME systematic review: BEME Guide No. 33.

NARCIS (Netherlands)

Querido, S.J.; Vergouw, D.; Wigersma, L.; Batenburg, R.S.; Rond, M.E.J. de; Cate, O.T.J. ten

2016-01-01

Introduction: Due to the lack of a theoretically embedded overview of the recent literature on medical career decision-making, this study provides an outline of these dynamics. Since differences in educational routes to the medical degree likely affect career choice dynamics, this study focuses on

Genomic and cranial phenotype data support multiple modern human dispersals from Africa and a southern route into Asia.

Science.gov (United States)

Reyes-Centeno, Hugo; Ghirotto, Silvia; Détroit, Florent; Grimaud-Hervé, Dominique; Barbujani, Guido; Harvati, Katerina

2014-05-20

Despite broad consensus on Africa as the main place of origin for anatomically modern humans, their dispersal pattern out of the continent continues to be intensely debated. In extant human populations, the observation of decreasing genetic and phenotypic diversity at increasing distances from sub-Saharan Africa has been interpreted as evidence for a single dispersal, accompanied by a series of founder effects. In such a scenario, modern human genetic and phenotypic variation was primarily generated through successive population bottlenecks and drift during a rapid worldwide expansion out of Africa in the Late Pleistocene. However, recent genetic studies, as well as accumulating archaeological and paleoanthropological evidence, challenge this parsimonious model. They suggest instead a "southern route" dispersal into Asia as early as the late Middle Pleistocene, followed by a separate dispersal into northern Eurasia. Here we test these competing out-of-Africa scenarios by modeling hypothetical geographical migration routes and assessing their correlation with neutral population differentiation, as measured by genetic polymorphisms and cranial shape variables of modern human populations from Africa and Asia. We show that both lines of evidence support a multiple-dispersals model in which Australo-Melanesian populations are relatively isolated descendants of an early dispersal, whereas other Asian populations are descended from, or highly admixed with, members of a subsequent migration event.

The demographics of human and malaria movement and migration patterns in East Africa.

Science.gov (United States)

Pindolia, Deepa K; Garcia, Andres J; Huang, Zhuojie; Smith, David L; Alegana, Victor A; Noor, Abdisalan M; Snow, Robert W; Tatem, Andrew J

2013-11-05

The quantification of parasite movements can provide valuable information for control strategy planning across all transmission intensities. Mobile parasite carrying individuals can instigate transmission in receptive areas, spread drug resistant strains and reduce the effectiveness of control strategies. The identification of mobile demographic groups, their routes of travel and how these movements connect differing transmission zones, potentially enables limited resources for interventions to be efficiently targeted over space, time and populations. National population censuses and household surveys provide individual-level migration, travel, and other data relevant for understanding malaria movement patterns. Together with existing spatially referenced malaria data and mathematical models, network analysis techniques were used to quantify the demographics of human and malaria movement patterns in Kenya, Uganda and Tanzania. Movement networks were developed based on connectivity and magnitudes of flow within each country and compared to assess relative differences between regions and demographic groups. Additional malaria-relevant characteristics, such as short-term travel and bed net use, were also examined. Patterns of human and malaria movements varied between demographic groups, within country regions and between countries. Migration rates were highest in 20-30 year olds in all three countries, but when accounting for malaria prevalence, movements in the 10-20 year age group became more important. Different age and sex groups also exhibited substantial variations in terms of the most likely sources, sinks and routes of migration and malaria movement, as well as risk factors for infection, such as short-term travel and bed net use. Census and survey data, together with spatially referenced malaria data, GIS and network analysis tools, can be valuable for identifying, mapping and quantifying regional connectivities and the mobility of different demographic

Post place and route design-technology co-optimization for scaling at single-digit nodes with constant ground rules

Science.gov (United States)

Mattii, Luca; Milojevic, Dragomir; Debacker, Peter; Berekovic, Mladen; Sherazi, Syed Muhammad Yasser; Chava, Bharani; Bardon, Marie Garcia; Schuddinck, Pieter; Rodopoulos, Dimitrios; Baert, Rogier; Gerousis, Vassilios; Ryckaert, Julien; Raghavan, Praveen

2018-01-01

Standard-cell design, technology choices, and place and route (P&R) efficiency are deeply interrelated in CMOS technology nodes below 10 nm, where lower number of tracks cells and higher pin densities pose increasingly challenging problems to the router in terms of congestion and pin accessibility. To evaluate and downselect the best solutions, a holistic design-technology co-optimization approach leveraging state-of-the-art P&R tools is thus necessary. We adopt such an approach using the imec N7 technology platform, with contacted poly pitch of 42 nm and tightest metal pitch of 32 nm, by comparing post P&R area of an IP block for different standard cell configurations, technology options, and cell height. Keeping the technology node and the set of ground rules unchanged, we demonstrate that a careful combination of these solutions can enable area gains of up to 50%, comparable with the area benefits of migrating to another node. We further demonstrate that these area benefits can be achieved at isoperformance with >20% reduced power. As at the end of the CMOS roadmap, conventional scaling enacted through pitch reduction is made more and more challenging by constraints imposed by lithography limits, material resistivity, manufacturability, and ultimately wafer cost, the approach shown herein offers a valid, attractive, and low-cost alternative.

Characterisation of contamination migration in the workplace

International Nuclear Information System (INIS)

Boulaud, D.; Laborde, J.C.; Pourprix, M.

1994-01-01

The Institute for Nuclear Safety and Protection (IPSN) has developed a procedure for characterising airborne contamination between processes and the workplace in nuclear facilities. It was initially intended to use this process to validate operator choices concerning the monitoring of indoor air contamination (personnel monitoring, and environmental detection at fixed locations), but also to optimise the fundamental parameters which have a more or less direct influence on potential exposure of staff in the workplace (at the same time optimising the contamination source, close confinement, process ventilation and general ventilation). In practice, the methods used to obtain these expert appraisals were usually based on experiments carried out in situ: (i) characterisation of aerosol contamination by accurate measurement of the nature, concentration and particle size distribution at various locations; (ii) characterisation of the migration of contamination by precise measurement involving gas and/or particle tracing techniques. In parallel with these experiments, a considerable effort was made to develop and qualify computer codes capable of predicting or estimating the migration of contamination through complex ventilated areas, by means of both fluid mechanics and aerosol science. (Author)

Ocean-wide Drivers of Migration Strategies and Their Influence on Population Breeding Performance in a Declining Seabird.

Science.gov (United States)

Fayet, Annette L; Freeman, Robin; Anker-Nilssen, Tycho; Diamond, Antony; Erikstad, Kjell E; Fifield, Dave; Fitzsimmons, Michelle G; Hansen, Erpur S; Harris, Mike P; Jessopp, Mark; Kouwenberg, Amy-Lee; Kress, Steve; Mowat, Stephen; Perrins, Chris M; Petersen, Aevar; Petersen, Ib K; Reiertsen, Tone K; Robertson, Gregory J; Shannon, Paula; Sigurðsson, Ingvar A; Shoji, Akiko; Wanless, Sarah; Guilford, Tim

2017-12-18

Which factors shape animals' migration movements across large geographical scales, how different migratory strategies emerge between populations, and how these may affect population dynamics are central questions in the field of animal migration [1] that only large-scale studies of migration patterns across a species' range can answer [2]. To address these questions, we track the migration of 270 Atlantic puffins Fratercula arctica, a red-listed, declining seabird, across their entire breeding range. We investigate the role of demographic, geographical, and environmental variables in driving spatial and behavioral differences on an ocean-basin scale by measuring puffins' among-colony differences in migratory routes and day-to-day behavior (estimated with individual daily activity budgets and energy expenditure). We show that competition and local winter resource availability are important drivers of migratory movements, with birds from larger colonies or with poorer local winter conditions migrating further and visiting less-productive waters; this in turn led to differences in flight activity and energy expenditure. Other behavioral differences emerge with latitude, with foraging effort and energy expenditure increasing when birds winter further north in colder waters. Importantly, these ocean-wide migration patterns can ultimately be linked with breeding performance: colony productivity is negatively associated with wintering latitude, population size, and migration distance, which demonstrates the cost of competition and migration on future breeding and the link between non-breeding and breeding periods. Our results help us to understand the drivers of animal migration and have important implications for population dynamics and the conservation of migratory species. Copyright © 2017 Elsevier Ltd. All rights reserved.

Impacts of Interannual Ocean Circulation Variability on Japanese Eel Larval Migration in the Western North Pacific Ocean.

Directory of Open Access Journals (Sweden)

Yu-Lin Chang

Full Text Available The Japanese eel larvae hatch near the West Mariana Ridge seamount chain and travel through the North Equatorial Current (NEC, the Kuroshio, and the Subtropical Countercurrent (STCC region during their shoreward migration toward East Asia. The interannual variability of circulation over the subtropical and tropical regions of the western North Pacific Ocean is affected by the Philippines-Taiwan Oscillation (PTO. This study examines the effect of the PTO on the Japanese eel larval migration routes using a three-dimensional (3D particle tracking method, including vertical and horizontal swimming behavior. The 3D circulation and hydrography used for particle tracking are from the ocean circulation reanalysis produced by the Japan Coastal Ocean Predictability Experiment 2 (JCOPE2. Our results demonstrate that bifurcation of the NEC and the strength and spatial variation of the Kuroshio affect the distribution and migration of eel larvae. During the positive phase of PTO, more virtual eels ("v-eels" can enter the Kuroshio to reach the south coast of Japan and more v-eels reach the South China Sea through the Luzon Strait; the stronger and more offshore swing of the Kuroshio in the East China Sea leads to fewer eels entering the East China Sea and the onshore movement of the Kuroshio to the south of Japan brings the eels closer to the Japanese coast. Significant differences in eel migration routes and distributions regulated by ocean circulation in different PTO phases can also affect the otolith increment. The estimated otolith increment suggests that eel age tends to be underestimated after six months of simulation due to the cooler lower layer temperature. Underestimation is more significant in the positive PTO years due to the wide distribution in higher latitudes than in the negative PTO years.

Impacts of Interannual Ocean Circulation Variability on Japanese Eel Larval Migration in the Western North Pacific Ocean.

Science.gov (United States)

Chang, Yu-Lin; Sheng, Jinyu; Ohashi, Kyoko; Béguer-Pon, Mélanie; Miyazawa, Yasumasa

2015-01-01

The Japanese eel larvae hatch near the West Mariana Ridge seamount chain and travel through the North Equatorial Current (NEC), the Kuroshio, and the Subtropical Countercurrent (STCC) region during their shoreward migration toward East Asia. The interannual variability of circulation over the subtropical and tropical regions of the western North Pacific Ocean is affected by the Philippines-Taiwan Oscillation (PTO). This study examines the effect of the PTO on the Japanese eel larval migration routes using a three-dimensional (3D) particle tracking method, including vertical and horizontal swimming behavior. The 3D circulation and hydrography used for particle tracking are from the ocean circulation reanalysis produced by the Japan Coastal Ocean Predictability Experiment 2 (JCOPE2). Our results demonstrate that bifurcation of the NEC and the strength and spatial variation of the Kuroshio affect the distribution and migration of eel larvae. During the positive phase of PTO, more virtual eels ("v-eels") can enter the Kuroshio to reach the south coast of Japan and more v-eels reach the South China Sea through the Luzon Strait; the stronger and more offshore swing of the Kuroshio in the East China Sea leads to fewer eels entering the East China Sea and the onshore movement of the Kuroshio to the south of Japan brings the eels closer to the Japanese coast. Significant differences in eel migration routes and distributions regulated by ocean circulation in different PTO phases can also affect the otolith increment. The estimated otolith increment suggests that eel age tends to be underestimated after six months of simulation due to the cooler lower layer temperature. Underestimation is more significant in the positive PTO years due to the wide distribution in higher latitudes than in the negative PTO years.

Southward autumn migration of waterfowl facilitates cross-continental transmission of the highly pathogenic avian influenza H5N1 virus

Science.gov (United States)

Xu, Yanjie; Gong, Peng; Wielstra, Ben; Si, Yali

2016-08-01

The highly pathogenic avian influenza subtype H5N1 (HPAI H5N1) is a worldwide zoonotic infectious disease, threatening humans, poultry and wild birds. The role of wild birds in the spread of HPAI H5N1 has previously been investigated by comparing disease spread patterns with bird migration routes. However, the different roles that the southward autumn and northward spring migration might play in virus transmission have hardly been explored. Using direction analysis, we analyze HPAI H5N1 transmission directions and angular concentration of currently circulating viral clades, and compare these with waterfowl seasonal migration directions along major waterfowl flyways. Out of 22 HPAI H5N1 transmission directions, 18 had both a southward direction and a relatively high concentration. Differences between disease transmission and waterfowl migration directions were significantly smaller for autumn than for spring migration. The four northward transmission directions were found along Asian flyways, where the initial epicenter of the virus was located. We suggest waterfowl first picked up the virus from East Asia, then brought it to the north via spring migration, and then spread it to other parts of world mainly by autumn migration. We emphasize waterfowl autumn migration plays a relatively important role in HPAI H5N1 transmission compared to spring migration.

Guidelines to elaborate a migration plan for digital terrestrial television in Venezuela

OpenAIRE

José Rafael Uzcátegui; José Francisco Torres; Nelson Pérez García; Luís Duque; Zeldívar Bruzual

2011-01-01

In October 2009, the Bolivarian Republic of Venezuela adopted the ISDB-Tb (Integrated Services Digital Broadcasting - Terrestrial Built On), released by Japan, with some improvement made by Brazil, as Digital Terrestrial Television (DTT) to be deployment in Venezuela. After standard choice, has been start the route towards the solution of transcendental aspects of legal and technical nature to enable the provision of digital terrestrial television service harmonized with the goals of true soc...

Spring migration of Northern Pintails from Texas and New Mexico, USA

Science.gov (United States)

Haukos, D.A.; Miller, M.R.; Orthmeyer, D.L.; Takekawa, John Y.; Fleskes, J.P.; Casazza, Michael L.; Perry, W.M.; Moon, J.A.

2006-01-01

We used satellite transmitters (platform transmitting terminals or PTTs) during 2002 and 2003 to document spring migration timing, routes, stopover sites, and nesting sites of adult female Northern Pintails (Anas acuta) from major wintering areas of the Gulf Coast (N = 20) and Playa Lakes Regions (PLR, N = 20) in Texas, and the Middle Rio Grande Valley, New Mexico (MRGV, N = 15). Some Pintails tagged in the MRGV continued movements into Mexico. Poor winter survival or PTT failure reduced sample size to 15 for PLR Pintails, 5 for Gulf Coast Pintails, and 11 for MRGV Pintails. Apparent winter survival was 66% lower for Texas Gulf Coast PTT-tagged Pintails than for those from the PLR and MRGV. Pintails from each area used different routes to their respective breeding grounds. PTT-tagged Pintails from the MRGV followed the Rio Grande Valley north to southern Colorado, before traveling on to the Dakotas and Canada or traveled northeast and joined the migration of PLR Pintails in Texas or Kansas. The latter made initial stops in Kansas, Nebraska, Colorado, or the Dakotas. Gulf Coast Pintails traveled through north-central Oklahoma or central Kansas. Pintails that had stopped first in Kansas or Nebraska tended to settle to nest in the United States. Wetland availability in the Prairie Pothole Region of the Northern Great Plains influenced nesting destinations of PTT-tagged Pintails, but individuals settled across a wide swath of northern North America. We did not detect any consistently-used spring staging areas. Therefore, negative impacts to any of the marked populations, or their wetland habitats, may have continental implications.

Indoor Semantic Modelling for Routing: The Two-Level Routing Approach for Indoor Navigation

Directory of Open Access Journals (Sweden)

Liu Liu

2017-11-01

Full Text Available Humans perform many activities indoors and they show a growing need for indoor navigation, especially in unfamiliar buildings such as airports, museums and hospitals. Complexity of such buildings poses many challenges for building managers and visitors. Indoor navigation services play an important role in supporting these indoor activities. Indoor navigation covers extensive topics such as: 1 indoor positioning and localization; 2 indoor space representation for navigation model generation; 3 indoor routing computation; 4 human wayfinding behaviours; and 5 indoor guidance (e.g., textual directories. So far, a large number of studies of pedestrian indoor navigation have presented diverse navigation models and routing algorithms/methods. However, the major challenge is rarely referred to: how to represent the complex indoor environment for pedestrians and conduct routing according to the different roles and sizes of users. Such complex buildings contain irregular shapes, large open spaces, complicated obstacles and different types of passages. A navigation model can be very complicated if the indoors are accurately represented. Although most research demonstrates feasible indoor navigation models and related routing methods in regular buildings, the focus is still on a general navigation model for pedestrians who are simplified as circles. In fact, pedestrians represent different sizes, motion abilities and preferences (e.g., described in user profiles, which should be reflected in navigation models and be considered for indoor routing (e.g., relevant Spaces of Interest and Points of Interest. In order to address this challenge, this thesis proposes an innovative indoor modelling and routing approach – two-level routing. It specially targets the case of routing in complex buildings for distinct users. The conceptual (first level uses general free indoor spaces: this is represented by the logical network whose nodes represent the spaces and edges

Multihop Wireless Networks Opportunistic Routing

CERN Document Server

Zeng, Kai; Li, Ming

2011-01-01

This book provides an introduction to opportunistic routing an emerging technology designed to improve the packet forwarding reliability, network capacity and energy efficiency of multihop wireless networks This book presents a comprehensive background to the technological challenges lying behind opportunistic routing. The authors cover many fundamental research issues for this new concept, including the basic principles, performance limit and performance improvement of opportunistic routing compared to traditional routing, energy efficiency and distributed opportunistic routing protocol desig

Research for annual travel-route changes of reindeer living around the Arctic Circle using satellite remote sensing

Science.gov (United States)

Suzuki, G.; Sakka, T.; Tashiro, T.; Kawamata, H.; Tatsuzawa, S.; Naruse, N.; Takahashi, Y.

2017-12-01

For a long time, nomads living in the Arctic Circle around Siberia have been making a living by hunting reindeer traditionally. Wild reindeer have a recurrent migration every year, however, the travel-route of reindeer has been changing recently, so the nomads cannot expect the route in their traditional experience. To support them, one of authors (Tatsuzawa) investigated the route by installing GPS transmitter to some reindeer. The reason of the changing route, however, remain unclear. Previous works indicated that the reason of changing the route must be a global warming, forest fires, thunders, and floods, but they only discuss only on the basis of measurements in specific area. The purpose of this study is to research why the arctic reindeer alter the travel route annually through 1) the annual change of vegetation (NDVI: normalized difference vegetation index) in reindeer ground, and through 2) the annual change of soil water content (mNDWI: modified normalized difference water index) which can be reflected precipitation near Lena river. First, we analyzed NDVI using MODIS images that can be observed over a wide area, filmed in July and August; the reindeer started to travel. We have compared the seasonal changes of the NDVI images with the trace obtained by GPS data from 2010 to 2012. Although NDVI images in July showed similar numerical values in every year, the satellite images taken at August 29 is annually different; NDVI values become lower (0.5 or less) when the reindeer travel to the north area in winter. This suggests that reindeer move to secure enough food in the end of summer. In contrast, mNDWI becomes high when the reindeer travel to the north area. The annual changes of the route may be related to the amount of rainfall.

Migration of rice planthoppers and their vectored re-emerging and novel rice viruses in East Asia.

Science.gov (United States)

Otuka, Akira

2013-10-28

This review examines recent studies of the migration of three rice planthoppers, Laodelphax striatellus, Sogatella furcifera, and Nilaparvata lugens, in East Asia. Laodelphax striatellus has recently broken out in Jiangsu province, eastern China. The population density in the province started to increase in the early 2000s and peaked in 2004. In 2005, Rice stripe virus (RSV) viruliferous rate of L. striatellus peaked at 31.3%. Since then, rice stripe disease spread severely across the whole province. Due to the migration of the RSV vectors, the rice stripe disease spread to neighboring countries Japan and Korea. An overseas migration of L. striatellus that occurred in 2008 was analyzed, when a slow-moving cold vortex, a type of low pressure system, reached western Japan from Jiangsu, carrying the insects into Japan. Subsequently the rice stripe diseases struck these areas in Japan severely. In Korea, similar situations occurred in 2009, 2011, and 2012. Their migration sources were also estimated to be in Jiangsu by backward trajectory analysis. Rice black-streaked dwarf virus, whose vector is L. striatellus, has recently re-emerged in eastern China, and the evidence for overseas migrations of the virus, just like the RSV's migrations, has been given. A method of predicting the overseas migration of L. striatellus has been developed by Japanese, Chinese, and Korean institutes. An evaluation of the prediction showed that this method properly predicted migration events that occurred in East Asia from 2008 to 2011. Southern rice black-streaked dwarf virus (SRBSDV) was first found in Guangdong province. Its vector is S. furcifera. An outbreak of SRBSDV occurred in southern China in 2009 and spread to Vietnam the same year. This disease and virus were also found in Japan in 2010. The epidemic triggered many migration studies to investigate concrete spring-summer migration routes in China, and the addition of migration sources for early arrivals in Guangdong and Guangxi

Environment, migration and the European demographic deficit

Science.gov (United States)

Harper, Sarah

2012-03-01

Many countries in the more developed world, and some in the less developed, are facing new economic and social pressures associated with the ageing of their populations. Europe, in particular, is forecast to have a demographic deficit, which may be alleviated by in-migration to the region. However, several commentators have proposed that Europe will not be able to successfully compete with other regions, in particular Asia, in the coming years for the skills it will require. This letter explores these themes, arguing that climate change will increase the attractiveness of Europe as a destination of economic choice for future skilled workers, to the detriment of more environmentally challenged regions.

Environment, migration and the European demographic deficit

International Nuclear Information System (INIS)

Harper, Sarah

2012-01-01

Many countries in the more developed world, and some in the less developed, are facing new economic and social pressures associated with the ageing of their populations. Europe, in particular, is forecast to have a demographic deficit, which may be alleviated by in-migration to the region. However, several commentators have proposed that Europe will not be able to successfully compete with other regions, in particular Asia, in the coming years for the skills it will require. This letter explores these themes, arguing that climate change will increase the attractiveness of Europe as a destination of economic choice for future skilled workers, to the detriment of more environmentally challenged regions. (letter)

Quantifying Migration Behaviour Using Net Squared Displacement Approach: Clarifications and Caveats.

Directory of Open Access Journals (Sweden)

Navinder J Singh

Full Text Available Estimating migration parameters of individuals and populations is vital for their conservation and management. Studies on animal movements and migration often depend upon location data from tracked animals and it is important that such data are appropriately analyzed for reliable estimates of migration and effective management of moving animals. The Net Squared Displacement (NSD approach for modelling animal movement is being increasingly used as it can objectively quantify migration characteristics and separate different types of movements from migration. However, the ability of NSD to properly classify the movement patterns of individuals has been criticized and issues related to study design arise with respect to starting locations of the data/animals, data sampling regime and extent of movement of species. We address the issues raised over NSD using tracking data from 319 moose (Alces alces in Sweden. Moose is an ideal species to test this approach, as it can be sedentary, nomadic, dispersing or migratory and individuals vary in their extent, timing and duration of migration. We propose a two-step process of using the NSD approach by first classifying movement modes using mean squared displacement (MSD instead of NSD and then estimating the extent, duration and timing of migration using NSD. We show that the NSD approach is robust to the choice of starting dates except when the start date occurs during the migratory phase. We also show that the starting location of the animal has a marginal influence on the correct quantification of migration characteristics. The number of locations per day (1-48 did not significantly affect the performance of non-linear mixed effects models, which correctly distinguished migration from other movement types, however, high-resolution data had a significant negative influence on estimates for the timing of migrations. The extent of movement, however, had an effect on the classification of movements, and

Metabolic routing of dietary nutrients in birds: effects of diet quality and macronutrient composition revealed using stable isotopes.

Science.gov (United States)

Podlesak, David W; McWilliams, Scott R

2006-01-01

During fall migration many songbirds switch from consuming primarily insects to consuming mostly fruit. Fruits with more carbohydrates and less protein may be sufficient to rebuild expended fat stores, but such fruits may be inadequate to replace catabolized protein. We manipulated the concentrations and isotopic signatures of macronutrients in diets fed to birds to study the effects of diet quality on metabolic routing of dietary nutrients. We estimated that approximately 45% and 75%, respectively, of the carbon in proteinaceous tissue of birds switched to high- or low-protein diets came from nonprotein dietary sources. In contrast, we estimated that approximately 100% and 20%-80%, respectively, of the nitrogen in proteinaceous tissues of birds switched to high- or low-protein diets was attributable to dietary protein. Thus, the routing and assimilation of dietary carbon and nitrogen differed depending on diet composition. As a result, delta (15)N of tissues collected from wild animals that consume high-quality diets may reliably indicate the dietary protein source, whereas delta (13)C of these same tissues is likely the product of metabolic routing of carbon from several macronutrients. These results have implications for how isotopic discrimination is best estimated and how we can study macronutrient routing in wild animals.

Fate of chlorinated fatty acids in migrating sockeye salmon and their transfer to arctic grayling

DEFF Research Database (Denmark)

Mu, Huiling; Ewald, G.; Nilsson, E.

2004-01-01

To investigate whether biotransport constitutes an entry route into pristine ecosystems for nonpersistent, nonvolatile xenobiotic compounds, extractable organically bound halogen in sockeye salmon (Oncorhynchus nerka) from Alaska was determined before and after spawning migration. The major...... organohalogen compounds in the salmon were halogenated fatty acids, predominantly chlorinated species that accounted for up to 35% of the extractable, organically bound chlorine (EOCl) in the fish tissues. The amount of chlorinated fatty acids in the salmon muscle decreased as a result of spawning migration....... The decrease was correlated with that of triacylglycerols in the salmon muscle, indicating the chlorinated fatty acids to be mobilized and metabolized to approximately the same extent as the other fatty acids. Chlorinated fatty acids were also transferred to the maturing roe in a manner similar...

Why Did People Move During the Great Recession? The Role of Economics in Migration Decisions

Directory of Open Access Journals (Sweden)

Brian L. Levy

2017-04-01

Full Text Available Labor migration offers an important mechanism to reallocate workers when there are regional differences in employment conditions. Whereas conventional wisdom suggests migration rates should increase during recessions as workers move out of areas that are hit hardest, initial evidence suggested that overall migration rates declined during the Great Recession, despite large regional differences in unemployment and growth rates. In this paper we use data from the American Community Survey to analyze internal migration trends before and during the economic downturn. First, we find only a modest decline in the odds of adults leaving distressed labor market areas during the Great Recession, which may result in part from challenges related to the housing price crash. Second, we estimate conditional logit models of destination choice for individuals who migrate across labor market areas; we find a substantial effect of economic factors such as labor demand, unemployment, and housing values. We also estimate latent class conditional logit models that test whether there is heterogeneity in preferences for destination characteristics among migrants. Over all, the latent class models suggest that roughly equal percentages of migrants were motivated by economic factors before and during the Great Recession. We conclude that fears of dramatic declines in labor migration seem to be unsubstantiated.

Why Did People Move During the Great Recession?: The Role of Economics in Migration Decisions.

Science.gov (United States)

Levy, Brian L; Mouw, Ted; Daniel Perez, Anthony

2017-04-01

Labor migration offers an important mechanism to reallocate workers when there are regional differences in employment conditions. Whereas conventional wisdom suggests migration rates should increase during recessions as workers move out of areas that are hit hardest, initial evidence suggested that overall migration rates declined during the Great Recession, despite large regional differences in unemployment and growth rates. In this paper, we use data from the American Community Survey to analyze internal migration trends before and during the economic downturn. First, we find only a modest decline in the odds of adults leaving distressed labor market areas during the recession, which may result in part from challenges related to the housing price crash. Second, we estimate conditional logit models of destination choice for individuals who migrate across labor market areas and find a substantial effect of economic factors such as labor demand, unemployment, and housing values. We also estimate latent class conditional logit models that test whether there is heterogeneity in preferences for destination characteristics among migrants. Over all, the latent class models suggest that roughly equal percentages of migrants were motivated by economic factors before and during the recession. We conclude that fears of dramatic declines in labor migration seem to be unsubstantiated.

Modeling Bird Migration under Climate Change: A Mechanistic Approach

Science.gov (United States)

Smith, James A.

2009-01-01

How will migrating birds respond to changes in the environment under climate change? What are the implications for migratory success under the various accelerated climate change scenarios as forecast by the Intergovernmental Panel on Climate Change? How will reductions or increased variability in the number or quality of wetland stop-over sites affect migratory bird species? The answers to these questions have important ramifications for conservation biology and wildlife management. Here, we describe the use of continental scale simulation modeling to explore how spatio-temporal changes along migratory flyways affect en-route migration success. We use an individually based, biophysical, mechanistic, bird migration model to simulate the movement of shorebirds in North America as a tool to study how such factors as drought and wetland loss may impact migratory success and modify migration patterns. Our model is driven by remote sensing and climate data and incorporates important landscape variables. The energy budget components of the model include resting, foraging, and flight, but presently predation is ignored. Results/Conclusions We illustrate our model by studying the spring migration of sandpipers through the Great Plains to their Arctic breeding grounds. Why many species of shorebirds have shown significant declines remains a puzzle. Shorebirds are sensitive to stop-over quality and spacing because of their need for frequent refueling stops and their opportunistic feeding patterns. We predict bird "hydrographs that is, stop-over frequency with latitude, that are in agreement with the literature. Mean stop-over durations predicted from our model for nominal cases also are consistent with the limited, but available data. For the shorebird species simulated, our model predicts that shorebirds exhibit significant plasticity and are able to shift their migration patterns in response to changing drought conditions. However, the question remains as to whether this

Differences in physical environmental characteristics between adolescents' actual and shortest cycling routes: a study using a Google Street View-based audit.

Science.gov (United States)

Verhoeven, Hannah; Van Hecke, Linde; Van Dyck, Delfien; Baert, Tim; Van de Weghe, Nico; Clarys, Peter; Deforche, Benedicte; Van Cauwenberg, Jelle

2018-05-29

The objective evaluation of the physical environmental characteristics (e.g. speed limit, cycling infrastructure) along adolescents' actual cycling routes remains understudied, although it may provide important insights into why adolescents prefer one cycling route over another. The present study aims to gain insight into the physical environmental characteristics determining the route choice of adolescent cyclists by comparing differences in physical environmental characteristics between their actual cycling routes and the shortest possible cycling routes. Adolescents (n = 204; 46.5% boys; 14.4 ± 1.2 years) recruited at secondary schools in and around Ghent (city in Flanders, northern part of Belgium) were instructed to wear a Global Positioning System device in order to identify cycling trips. For all identified cycling trips, the shortest possible route that could have been taken was calculated. Actual cycling routes that were not the shortest possible cycling routes were divided into street segments. Segments were audited with a Google Street View-based tool to assess physical environmental characteristics along actual and shortest cycling routes. Out of 160 actual cycling trips, 73.1% did not differ from the shortest possible cycling route. For actual cycling routes that were not the shortest cycling route, a speed limit of 30 km/h, roads having few buildings with windows on the street side and roads without cycle lane were more frequently present compared to the shortest possible cycling routes. A mixed land use, roads with commercial destinations, arterial roads, cycle lanes separated from traffic by white lines, small cycle lanes and cycle lanes covered by lighting were less frequently present along actual cycling routes compared to the shortest possible cycling routes. Results showed that distance mainly determines the route along which adolescents cycle. In addition, adolescents cycled more along residential streets (even if no cycle lane was

Migration, legality, and fertility regulation: Abortion and contraception among migrants and natives in Russia

Directory of Open Access Journals (Sweden)

Victor Agadjanian

2018-04-01

Full Text Available Background: Migrant-vs.-native differentials in reproductive behavior are typically examined through the prism of socioeconomic and cultural constraints that characterize the migration process and experiences. However, the literature seldom factors in migrant legal status because necessary data is rarely available. Objective: The study seeks to fill this important gap by looking at variations in induced abortion and contraceptive use not only between migrants and nonmigrants but also among migrants of different legal statuses in the Russian Federation. Methods: We use unique survey data collected in urban Russia from Central Asian working migrant women of different legal statuses - regularized vs. irregular - as well as their native counterparts. Binomial and multinomial logistic regressions are fitted to model abortion experience and current contraceptive use and method choice. Results: The results point to higher overall use of abortion among natives, but also to significant differences between migrants with regularized and irregular legal statuses. With respect to contraception, while no variation in overall use between migrants and natives or between migrants of different legal statuses is detected, instructive migrant-vs.-native differences in method choice emerge. Conclusions: The findings underscore the importance of migrants' legal status, along with their other characteristics, for a better understanding of their reproductive behavior and for more effective corresponding policies. Contribution: The study offers pioneering insights into the intersection of migration, legality, and fertility in contemporary Russia and contributes to the cross-national scholarship on migration and reproductive behavior and health.

SAFEBIKE: A Bike-sharing Route Recommender with Availability Prediction and Safe Routing

OpenAIRE

Zhong, Weisheng; Chen, Fanglan; Fu, Kaiqun; Lu, Chang-Tien

2017-01-01

This paper presents SAFEBIKE, a novel route recommendation system for bike-sharing service that utilizes station information to infer the number of available bikes in dock and recommend bike routes according to multiple factors such as distance and safety level. The system consists of a station level availability predictor that predicts bikes and docks amount at each station, and an efficient route recommendation service that considers safety and bike/dock availability factors. It targets use...

Personal continuous route pattern mining

Institute of Scientific and Technical Information of China (English)

Qian YE; Ling CHEN; Gen-cai CHEN

2009-01-01

In the daily life, people often repeat regular routes in certain periods. In this paper, a mining system is developed to find the continuous route patterns of personal past trips. In order to count the diversity of personal moving status, the mining system employs the adaptive GPS data recording and five data filters to guarantee the clean trips data. The mining system uses a client/server architecture to protect personal privacy and to reduce the computational load. The server conducts the main mining procedure but with insufficient information to recover real personal routes. In order to improve the scalability of sequential pattern mining, a novel pattern mining algorithm, continuous route pattern mining (CRPM), is proposed. This algorithm can tolerate the different disturbances in real routes and extract the frequent patterns. Experimental results based on nine persons' trips show that CRPM can extract more than two times longer route patterns than the traditional route pattern mining algorithms.

Optimization of the Fabrication Route of Ferritic/Martensitic ODS Cladding Tubes: Metallurgical Approach and Pilgering Numerical Modeling

International Nuclear Information System (INIS)

Logé, R.E.; Vanegas-Marques, E.; Mocellin, K.; Toualbi, L.; Carlan, Y. de

2013-01-01

Conclusions: • Fabrication route of 9Cr-ODS (martensitic) alloys is well controlled. • Fabrication route of 14Cr-ODS (ferritic) should be further optimized. • The choice between a ferritic or a martensitic grade is not already done, it will depend also on the behaviour under irradiation, the corrosion resistance … • Part of the optimization can rely on numerical simulation of pilgering: • The constitutive behaviour is an essential ingredient for process optimization: appropriate cyclic laws must be used. • The numerical analysis can look at cracking risks, final yield stress, and even residual stress state or surface roughness. • HPTR laboratory approaches can be translated to the (industrial) VMR process provided some additional adjustments in the numerical code

State-Dependent Decisions Cause Apparent Violations of Rationality in Animal Choice

Science.gov (United States)

Schuck-Paim, Cynthia; Pompilio, Lorena

2004-01-01

Normative models of choice in economics and biology usually expect preferences to be consistent across contexts, or “rational” in economic language. Following a large body of literature reporting economically irrational behaviour in humans, breaches of rationality by animals have also been recently described. If proven systematic, these findings would challenge long-standing biological approaches to behavioural theorising, and suggest that cognitive processes similar to those claimed to cause irrationality in humans can also hinder optimality approaches to modelling animal preferences. Critical differences between human and animal experiments have not, however, been sufficiently acknowledged. While humans can be instructed conceptually about the choice problem, animals need to be trained by repeated exposure to all contingencies. This exposure often leads to differences in state between treatments, hence changing choices while preserving rationality. We report experiments with European starlings demonstrating that apparent breaches of rationality can result from state-dependence. We show that adding an inferior alternative to a choice set (a “decoy”) affects choices, an effect previously interpreted as indicating irrationality. However, these effects appear and disappear depending on whether state differences between choice contexts are present or not. These results open the possibility that some expressions of maladaptive behaviour are due to oversights in the migration of ideas between economics and biology, and suggest that key differences between human and nonhuman research must be recognised if ideas are to safely travel between these fields. PMID:15550984

State-dependent decisions cause apparent violations of rationality in animal choice.

Directory of Open Access Journals (Sweden)

Cynthia Schuck-Paim

2004-12-01

Full Text Available Normative models of choice in economics and biology usually expect preferences to be consistent across contexts, or "rational" in economic language. Following a large body of literature reporting economically irrational behaviour in humans, breaches of rationality by animals have also been recently described. If proven systematic, these findings would challenge long-standing biological approaches to behavioural theorising, and suggest that cognitive processes similar to those claimed to cause irrationality in humans can also hinder optimality approaches to modelling animal preferences. Critical differences between human and animal experiments have not, however, been sufficiently acknowledged. While humans can be instructed conceptually about the choice problem, animals need to be trained by repeated exposure to all contingencies. This exposure often leads to differences in state between treatments, hence changing choices while preserving rationality. We report experiments with European starlings demonstrating that apparent breaches of rationality can result from state-dependence. We show that adding an inferior alternative to a choice set (a "decoy" affects choices, an effect previously interpreted as indicating irrationality. However, these effects appear and disappear depending on whether state differences between choice contexts are present or not. These results open the possibility that some expressions of maladaptive behaviour are due to oversights in the migration of ideas between economics and biology, and suggest that key differences between human and nonhuman research must be recognised if ideas are to safely travel between these fields.

State-dependent decisions cause apparent violations of rationality in animal choice.

Science.gov (United States)

Schuck-Paim, Cynthia; Pompilio, Lorena; Kacelnik, Alex

2004-12-01

Normative models of choice in economics and biology usually expect preferences to be consistent across contexts, or "rational" in economic language. Following a large body of literature reporting economically irrational behaviour in humans, breaches of rationality by animals have also been recently described. If proven systematic, these findings would challenge long-standing biological approaches to behavioural theorising, and suggest that cognitive processes similar to those claimed to cause irrationality in humans can also hinder optimality approaches to modelling animal preferences. Critical differences between human and animal experiments have not, however, been sufficiently acknowledged. While humans can be instructed conceptually about the choice problem, animals need to be trained by repeated exposure to all contingencies. This exposure often leads to differences in state between treatments, hence changing choices while preserving rationality. We report experiments with European starlings demonstrating that apparent breaches of rationality can result from state-dependence. We show that adding an inferior alternative to a choice set (a "decoy") affects choices, an effect previously interpreted as indicating irrationality. However, these effects appear and disappear depending on whether state differences between choice contexts are present or not. These results open the possibility that some expressions of maladaptive behaviour are due to oversights in the migration of ideas between economics and biology, and suggest that key differences between human and nonhuman research must be recognised if ideas are to safely travel between these fields.

The Effect of Trail Pheromone and Path Confinement on Learning of Complex Routes in the Ant Lasius niger.

Science.gov (United States)

Czaczkes, Tomer J; Weichselgartner, Tobias; Bernadou, Abel; Heinze, Jürgen

2016-01-01

Route learning is key to the survival of many central place foragers, such as bees and many ants. For ants which lay pheromone trails, the presence of a trail may act as an important source of information about whether an error has been made. The presence of trail pheromone has been demonstrated to support route learning, and the effect of pheromones on route choice have been reported to persist even after the pheromones have been removed. This could be explained in two ways: the pheromone may constrain the ants onto the correct route, thus preventing errors and aiding learning. Alternatively, the pheromones may act as a 'reassurance', signalling that the learner is on the right path and that learning the path is worthwhile. Here, we disentangle pheromone presence from route confinement in order to test these hypotheses, using the ant Lasius niger as a model. Unexpectedly, we did not find any evidence that pheromones support route learning. Indeed, there was no evidence that ants confined to the correct route learned at all. Thus, while we cannot support the 'reassurance' hypothesis, we can rule out the 'confinement' hypothesis. Other findings, such as a reduction in pheromone deposition in the presence of trail pheromones, are remarkably consistent with previous experiments. As previously reported, ants which make errors on their outward journey upregulate pheromone deposition on their return. Surprisingly, ants which would go on to make an error down-regulate pheromone deposition on their outward journey, hinting at a capacity for ants to gauge the quality of their own memories.

The Effect of Trail Pheromone and Path Confinement on Learning of Complex Routes in the Ant Lasius niger.

Directory of Open Access Journals (Sweden)

Tomer J Czaczkes

Full Text Available Route learning is key to the survival of many central place foragers, such as bees and many ants. For ants which lay pheromone trails, the presence of a trail may act as an important source of information about whether an error has been made. The presence of trail pheromone has been demonstrated to support route learning, and the effect of pheromones on route choice have been reported to persist even after the pheromones have been removed. This could be explained in two ways: the pheromone may constrain the ants onto the correct route, thus preventing errors and aiding learning. Alternatively, the pheromones may act as a 'reassurance', signalling that the learner is on the right path and that learning the path is worthwhile. Here, we disentangle pheromone presence from route confinement in order to test these hypotheses, using the ant Lasius niger as a model. Unexpectedly, we did not find any evidence that pheromones support route learning. Indeed, there was no evidence that ants confined to the correct route learned at all. Thus, while we cannot support the 'reassurance' hypothesis, we can rule out the 'confinement' hypothesis. Other findings, such as a reduction in pheromone deposition in the presence of trail pheromones, are remarkably consistent with previous experiments. As previously reported, ants which make errors on their outward journey upregulate pheromone deposition on their return. Surprisingly, ants which would go on to make an error down-regulate pheromone deposition on their outward journey, hinting at a capacity for ants to gauge the quality of their own memories.

New Route Choice Models

DEFF Research Database (Denmark)

Nielsen, Otto Anker

udgave af SUE, der rummer to typer stokastiske faktorer - den ene beskriver trafikanters 'oplevede' rejsemodstande på stræknings-niveauet (som i den traditionelle SUE), mens den anden beskriver forskelle i trafikanternes præferen-cer. Denne model har vist sig at give en mere realistisk beskrivelse af...

MIGRATION PATTERNS, USE OF STOPOVER AREAS, AND AUSTRAL SUMMER MOVEMENTS OF SWAINSON'S HAWKS.

Science.gov (United States)

Kochert, Michael N; Fuller, Mark R; Schueck, Linda S; Bond, Laura; Bechard, Marc J; Woodbridge, Brian; Holroyd, Geoff; Martell, Mark; Banasch, Ursula

From 1995-1998, we tracked movements of adult Swainson's Hawks ( Buteo swainsoni ) using satellite telemetry to characterize migration, important stopover areas, and austral summer movements. We tagged 46 hawks from July - September on their nesting grounds in seven U.S. states and two Canadian provinces. Swainson's Hawks basically followed three routes south on a broad front, converged along the east coast of central Mexico, and followed a concentrated corridor to a communal austral summer area in central Argentina. North of 20° N, southward and northward tracks differed little for individuals from east of the Continental Divide but differed greatly (up to 1700 km) for individuals from west of the Continental Divide. Hawks left the breeding grounds mid-August to mid-October; departure dates did not differ by location, year, or sex. South migration lasted 42 to 98 days, and north migration took 51 to 82 days. On south migration, 36% of the Swainson's Hawks departed the nesting grounds nearly 3 weeks earlier than the other radio marked hawks and made stopovers 9.0 - 26.0 days long in seven separate areas, mainly in the southern Great Plains, southern Arizona and New Mexico, and north-central Mexico. The austral period lasted 76 to 128 days. All Swainson's Hawks used a core area in central Argentina within 23% of the 738800 km 2 austral summer range where they frequently moved long distances (up to 1600 km). Conservation of Swainson's Hawks must be an international effort that considers habitats used during nesting and non-nesting seasons including migration stopovers.

Examining speed versus selection in connectivity models using elk migration as an example

Science.gov (United States)

Brennan, Angela; Hanks, Ephraim M.; Merkle, Jerod A.; Cole, Eric K.; Dewey, Sarah R.; Courtemanch, Alyson B.; Cross, Paul C.

2018-01-01

ContextLandscape resistance is vital to connectivity modeling and frequently derived from resource selection functions (RSFs). RSFs estimate relative probability of use and tend to focus on understanding habitat preferences during slow, routine animal movements (e.g., foraging). Dispersal and migration, however, can produce rarer, faster movements, in which case models of movement speed rather than resource selection may be more realistic for identifying habitats that facilitate connectivity.ObjectiveTo compare two connectivity modeling approaches applied to resistance estimated from models of movement rate and resource selection.MethodsUsing movement data from migrating elk, we evaluated continuous time Markov chain (CTMC) and movement-based RSF models (i.e., step selection functions [SSFs]). We applied circuit theory and shortest random path (SRP) algorithms to CTMC, SSF and null (i.e., flat) resistance surfaces to predict corridors between elk seasonal ranges. We evaluated prediction accuracy by comparing model predictions to empirical elk movements.ResultsAll connectivity models predicted elk movements well, but models applied to CTMC resistance were more accurate than models applied to SSF and null resistance. Circuit theory models were more accurate on average than SRP models.ConclusionsCTMC can be more realistic than SSFs for estimating resistance for fast movements, though SSFs may demonstrate some predictive ability when animals also move slowly through corridors (e.g., stopover use during migration). High null model accuracy suggests seasonal range data may also be critical for predicting direct migration routes. For animals that migrate or disperse across large landscapes, we recommend incorporating CTMC into the connectivity modeling toolkit.

In vivo evaluation of dosage forms: application of gamma scintigraphy to non-enteral routes of administration.

Science.gov (United States)

Meseguer, G; Gurny, R; Buri, P

1994-01-01

The trend to deliver drugs to defined areas of the body involves sophisticated carriers systems. In addition to the in vitro drug release profile one must be aware of the in vivo behaviour of the dosage form and the drug. Gamma scintigraphy is an elegant way to gain insights of the actual in vivo distribution pattern of dosage forms. This technique relies on the use of radioactive tracers included into the medicament and selected so as to enable an optimum detection by a gamma ray camera. The choice of a convenient label enables the in vivo determination of the targeting of the formulation administered through a large number of routes. The present paper reviews applications of gamma scintigraphy for the evaluation of dosage forms administered by the parenteral, rectal, buccal, nasal, pulmonary, and ophthalmic routes.

Class network routing

Science.gov (United States)

Bhanot, Gyan [Princeton, NJ; Blumrich, Matthias A [Ridgefield, CT; Chen, Dong [Croton On Hudson, NY; Coteus, Paul W [Yorktown Heights, NY; Gara, Alan G [Mount Kisco, NY; Giampapa, Mark E [Irvington, NY; Heidelberger, Philip [Cortlandt Manor, NY; Steinmacher-Burow, Burkhard D [Mount Kisco, NY; Takken, Todd E [Mount Kisco, NY; Vranas, Pavlos M [Bedford Hills, NY

2009-09-08

Class network routing is implemented in a network such as a computer network comprising a plurality of parallel compute processors at nodes thereof. Class network routing allows a compute processor to broadcast a message to a range (one or more) of other compute processors in the computer network, such as processors in a column or a row. Normally this type of operation requires a separate message to be sent to each processor. With class network routing pursuant to the invention, a single message is sufficient, which generally reduces the total number of messages in the network as well as the latency to do a broadcast. Class network routing is also applied to dense matrix inversion algorithms on distributed memory parallel supercomputers with hardware class function (multicast) capability. This is achieved by exploiting the fact that the communication patterns of dense matrix inversion can be served by hardware class functions, which results in faster execution times.

mizuRoute version 1: A river network routing tool for a continental domain water resources applications

Science.gov (United States)

Mizukami, Naoki; Clark, Martyn P.; Sampson, Kevin; Nijssen, Bart; Mao, Yixin; McMillan, Hilary; Viger, Roland; Markstrom, Steven; Hay, Lauren E.; Woods, Ross; Arnold, Jeffrey R.; Brekke, Levi D.

2016-01-01

This paper describes the first version of a stand-alone runoff routing tool, mizuRoute. The mizuRoute tool post-processes runoff outputs from any distributed hydrologic model or land surface model to produce spatially distributed streamflow at various spatial scales from headwater basins to continental-wide river systems. The tool can utilize both traditional grid-based river network and vector-based river network data. Both types of river network include river segment lines and the associated drainage basin polygons, but the vector-based river network can represent finer-scale river lines than the grid-based network. Streamflow estimates at any desired location in the river network can be easily extracted from the output of mizuRoute. The routing process is simulated as two separate steps. First, hillslope routing is performed with a gamma-distribution-based unit-hydrograph to transport runoff from a hillslope to a catchment outlet. The second step is river channel routing, which is performed with one of two routing scheme options: (1) a kinematic wave tracking (KWT) routing procedure; and (2) an impulse response function – unit-hydrograph (IRF-UH) routing procedure. The mizuRoute tool also includes scripts (python, NetCDF operators) to pre-process spatial river network data. This paper demonstrates mizuRoute's capabilities to produce spatially distributed streamflow simulations based on river networks from the United States Geological Survey (USGS) Geospatial Fabric (GF) data set in which over 54 000 river segments and their contributing areas are mapped across the contiguous United States (CONUS). A brief analysis of model parameter sensitivity is also provided. The mizuRoute tool can assist model-based water resources assessments including studies of the impacts of climate change on streamflow.

Differences in route-learning performance and correlations among abilities between persons with and without Down syndrome

Directory of Open Access Journals (Sweden)

Megan eDavis

2014-12-01

Full Text Available Two experiments are reported that evaluated route learning of youth with DS, youth with Intellectual Disability and not DS (ID, and typically developing children (TD matched on Mental Age (MA. In both experiments, participants learned routes with eight choice-points presented via computer. Several objects were placed along the route that could be used as landmarks. Participants were shown the correct route once and then were asked retraced the route without assistance. In Experiment 1 we found that the TD children and ID participants performed very similarly. They learned the route in the same number of attempts, committed the same number of errors while learning the route, and recalled approximately the same number of landmarks. The participants with DS performed significantly worse on both measures of navigation (attempts and errors and also recalled significantly fewer landmarks. In Experiment 2, we attempted to reduce TD and ID vs DS differences by focusing participants’ attention on the landmarks. Half of the participants in each group were instructed to identify the landmarks as they passed them the first time. The participants with DS again committed more errors than the participants in the ID and TD groups in the navigation task. In addition, they recalled fewer landmarks. While landmark identification improved landmark memory for both groups, it did not have a significant impact on navigation. Participants with DS still performed more poorly than did the TD and ID participants. Of additional interest, we observed that the performance of persons with DS correlated with different ability measures than did the performance of the other groups. The results the two experiments point to a problem in navigation for persons with DS that exceeds expectations based solely on intellectual level.

Route prediction model of infectious diseases for 2018 Winter Olympics in Korea

International Nuclear Information System (INIS)

Kim, Eungyeong; Lee, Seok; Byun, Young Tae; Kim, Jae Hun; Lee, Taikjin; Lee, Hyuk-jae

2014-01-01

There are many types of respiratory infectious diseases caused by germs, virus, mycetes and parasites. Researchers recently have tried to develop mathematical models to predict the epidemic of infectious diseases. However, with the development of ground transportation system in modern society, the spread of infectious diseases became faster and more complicated in terms of the speed and the pathways. The route of infectious diseases during Vancouver Olympics was predicted based on the Susceptible-Infectious-Recovered (SIR) model. In this model only the air traffic as an essential factor for the intercity migration of infectious diseases was involved. Here, we propose a multi-city transmission model to predict the infection route during 2018 Winter Olympics in Korea based on the pre-existing SIR model. Various types of transportation system such as a train, a car, a bus, and an airplane for the interpersonal contact in both inter- and intra-city are considered. Simulation is performed with assumptions and scenarios based on realistic factors including demographic, transportation and diseases data in Korea. Finally, we analyze an economic profit and loss caused by the variation of the number of tourists during the Olympics

Route prediction model of infectious diseases for 2018 Winter Olympics in Korea

Science.gov (United States)

Kim, Eungyeong; Lee, Seok; Byun, Young Tae; Kim, Jae Hun; Lee, Hyuk-jae; Lee, Taikjin

2014-03-01

There are many types of respiratory infectious diseases caused by germs, virus, mycetes and parasites. Researchers recently have tried to develop mathematical models to predict the epidemic of infectious diseases. However, with the development of ground transportation system in modern society, the spread of infectious diseases became faster and more complicated in terms of the speed and the pathways. The route of infectious diseases during Vancouver Olympics was predicted based on the Susceptible-Infectious-Recovered (SIR) model. In this model only the air traffic as an essential factor for the intercity migration of infectious diseases was involved. Here, we propose a multi-city transmission model to predict the infection route during 2018 Winter Olympics in Korea based on the pre-existing SIR model. Various types of transportation system such as a train, a car, a bus, and an airplane for the interpersonal contact in both inter- and intra-city are considered. Simulation is performed with assumptions and scenarios based on realistic factors including demographic, transportation and diseases data in Korea. Finally, we analyze an economic profit and loss caused by the variation of the number of tourists during the Olympics.

Informed Choice in the German Mammography Screening Program by Education and Migrant Status: Survey among First-Time Invitees.

Directory of Open Access Journals (Sweden)

Eva-Maria Berens

Full Text Available Breast cancer is the most prevalent cancer among women and mammography screening programs are seen as a key strategy to reduce breast cancer mortality. In Germany, women are invited to the population-based mammography screening program between ages 50 to 69. It is still discussed whether the benefits of mammography screening outweigh its harms. Therefore, the concept of informed choice comprising knowledge, attitude and intention has gained importance. The objective of this observational study was to assess the proportion of informed choices among women invited to the German mammography screening program for the first time. A representative sample of 17,349 women aged 50 years from a sub-region of North Rhine Westphalia was invited to participate in a postal survey. Turkish immigrant women were oversampled. The effects of education level and migration status on informed choice and its components were assessed. 5,847 (33.7% women responded to the postal questionnaire of which 4,113 were used for analyses. 31.5% of the women had sufficient knowledge. The proportion of sufficient knowledge was lower among immigrants and among women with low education levels. The proportion of women making informed choices was low (27.1%, with similar associations with education level and migration status. Women of low (OR 2.75; 95% CI 2.18-3.46 and medium education level (OR 1.49; 95% CI 1.27-1.75 were more likely to make an uninformed choice than women of high education level. Turkish immigrant women had the greatest odds for making an uninformed choice (OR 5.30, 95% CI 1.92-14.66 compared to non-immigrant women. Other immigrant women only had slightly greater odds for making an uninformed choice than non-immigrant women. As immigrant populations and women with low education level have been shown to have poor knowledge, they need special attention in measures to increase knowledge and thus informed choices.

Developing an eco-routing application.

Science.gov (United States)

2014-01-01

The study develops eco-routing algorithms and investigates and quantifies the system-wide impacts of implementing an eco-routing system. Two eco-routing algorithms are developed: one based on vehicle sub-populations (ECO-Subpopulation Feedback Assign...

Temporal migration patterns between natal locations of ruby-throated hummingbirds (Archilochus colubris) and their Gulf Coast stopover site.

Science.gov (United States)

Zenzal, Theodore J; Contina, Andrea J; Kelly, Jeffrey F; Moore, Frank R

2018-01-01

Autumn latitudinal migrations generally exhibit one of two different temporal migration patterns: type 1 where southern populations migrate south before northern populations, or type 2 where northern populations overtake southern populations en route . The ruby-throated hummingbird ( Archilochus colubris ) is a species with an expansive breeding range, which allows opportunities to examine variation in the timing of migration. Our objective was to determine a relationship between natal origin of ruby-throated hummingbirds and arrival at a Gulf coast stopover site; and if so, what factors, such as differences in body size across the range as well as the cost of migration, might drive such a pattern. To carry out our objectives, we captured hummingbirds at a coastal stopover site during autumn migration, at which time we collected feathers from juveniles for analysis of hydrogen stable isotopes. Using the hydrogen stable isotope gradient of precipitation across North America and published hydrogen isotope values of feathers from populations of breeding ruby-throated hummingbirds, we assigned migrants to probable natal latitudes. Our results confirm that individuals from across the range (30-50° N) stopover along the Gulf of Mexico and there is a positive relationship between arrival day and latitude, suggesting a type 1 migration pattern. We also found no relationship between fuel load (proxy for migration cost) or fat-free body mass (proxy for body size) and natal latitude. Our results, coupled with previous work on the spatial migration patterns of hummingbirds, show a type 1 chain migration pattern. While the mechanisms we tested do not seem to influence the evolution of migratory patterns, other factors such as resource availability may play a prominent role in the evolution of this migration system.

Tuberculosis, human rights and ethics considerations along the route of a highly vulnerable migrant from sub-Saharan Africa to Europe.

Science.gov (United States)

Wild, V; Jaff, D; Shah, N S; Frick, M

2017-10-01

Migrant health is a critical public health issue, and in many countries attention to this topic has focused on the link between migration and communicable diseases, including tuberculosis (TB). When creating public health policies to address the complex challenges posed by TB and migration, countries should focus these policies on evidence, ethics, and human rights. This paper traces a commonly used migration route from sub-Saharan Africa to Europe, identifying situations at each stage in which human rights and ethical values might be affected in relation to TB care. This illustration provides the basis for discussing TB and migration from the perspective of human rights, with a focus on the right to health. We then highlight three strands of discussion in the ethics and justice literature in an effort to develop more comprehensive ethics of migrant health. These strands include theories of global justice and global health ethics, the creation of 'firewalls' to separate enforcement of immigration law from protection of human rights, and the importance of non-stigmatization to health justice. The paper closes by reflecting briefly on how TB programs can better incorporate human rights and ethical principles and values into public health practice.

The Edge Set Cost of the Vehicle Routing Problem with Time Windows

DEFF Research Database (Denmark)

Reinhardt, Line Blander; Jepsen, Mads Kehlet; Pisinger, David

2016-01-01

. The certifications and investments impose a cost for the company while they also give unlimited usage of a set of roads to all vehicles belonging to the company. This violates the traditional assumption that the path between two destinations is well defined and independent of other choices. Different versions......We consider an important generalization of the vehicle routing problem with time windows in which a fixed cost must be paid for accessing a set of edges. This fixed cost could reflect payment for toll roads, investment in new facilities, the need for certifications, and other costly investments...

Arthropods and associated arthropod-borne diseases transmitted by migrating birds. The case of ticks and tick-borne pathogens.

Science.gov (United States)

Sparagano, Olivier; George, David; Giangaspero, Annunziata; Špitalská, Eva

2015-09-30

Geographic spread of parasites and pathogens poses a constant risk to animal health and welfare, particularly given that climate change is expected to potentially expand appropriate ranges for many key species. The spread of deleterious organisms via trade routes and human travelling is relatively closely controlled, though represents only one possible means of parasite/pathogen distribution. The transmission via natural parasite/pathogen movement between geographic locales, is far harder to manage. Though the extent of such movement may be limited by the relative inability of many parasites and pathogens to actively migrate, passive movement over long distances may still occur via migratory hosts. This paper reviews the potential role of migrating birds in the transfer of ectoparasites and pathogens between geographic locales, focusing primarily on ticks. Bird-tick-pathogen relationships are considered, and evidence provided of long-range parasite/pathogen transfer from one location to another during bird migration events. As shown in this paper not only many different arthropod species are carried by migrating birds but consequently these pests carry many different pathogens species which can be transmitted to the migrating birds or to other animal species when those arthropods are dropping during these migrations. Data available from the literature are provided highlighting the need to understand better dissemination paths and disease epidemiology. Copyright © 2015 Elsevier B.V. All rights reserved.

Migrations and swimming capabilities of endangered pallid sturgeon (Scaphirhynchus albus) to guide passage designs in the fragmented Yellowstone River

Science.gov (United States)

Braaten, P. J.; Elliott, Caroline M.; Rhoten, Jason C.; Fuller, D. B.; McElroy, Brandon J.

2015-01-01

Fragmentation of the Yellowstone River is hypothesized to preclude recruitment of endangered Scaphirhynchus albus (pallid sturgeon) by impeding upstream spawning migrations and access to upstream spawning areas, thereby limiting the length of free-flowing river required for survival of early life stages. Building on this hypothesis, the reach of the Yellowstone River affected by Intake Diversion Dam (IDD) is targeted for modification. Structures including a rock ramp and by-pass channel have been proposed as restoration alternatives to facilitate passage. Limited information on migrations and swimming capabilities of pallid sturgeon is available to guide engineering design specifications for the proposed structures. Migration behavior, pathways (channel routes used during migrations), and swimming capabilities of free-ranging wild adult pallid sturgeon were examined using radiotelemetry, and complemented with hydraulic data obtained along the migration pathways. Migrations of 12–26% of the telemetered pallid sturgeon population persisted to IDD, but upstream passage over the dam was not detected. Observed migration pathways occurred primarily through main channel habitats; however, migrations through side channels up to 3.9 km in length were documented. The majority of pallid sturgeon used depths of 2.2–3.4 m and mean water velocities of 0.89–1.83 m/s while migrating. Results provide inferences on depths, velocities, and habitat heterogeneity of reaches successfully negotiated by pallid sturgeon that may be used to guide designs for structures facilitating passage at IDD. Passage will provide connectivity to potential upstream spawning areas on the Yellowstone River, thereby increasing the likelihood of recruitment for this endangered species.

Migration of rice planthoppers and their vectored re-emerging and novel rice viruses in East Asia

Directory of Open Access Journals (Sweden)

Akira eOtuka

2013-10-01

Full Text Available This review examines recent studies of the migration of three rice planthoppers, Laodelphax striatellus, Sogatella furcifera, and Nilaparvata lugens, in East Asia. Laodelphax striatellus has recently broken out in Jiangsu province, eastern China. The population density in the province started to increase in the early 2000s and peaked in 2004. In 2005, Rice stripe virus (RSV viruliferous rate of L. striatellus peaked at 31.3%. Since then, rice stripe disease spread severely across the whole province. Due to the migration of the RSV vectors, the rice stripe disease spread to neighboring countries Japan and Korea. An overseas migration of L. striatellus that occurred in 2008 was analyzed, when a slow-moving cold vortex, a type of low pressure system, reached western Japan from Jiangsu, carrying the insects into Japan. Subsequently the rice stripe diseases struck these areas in Japan severely. In Korea, similar situations occurred in 2009, 2011, and 2012. Their migration sources were also estimated to be in Jiangsu by backward trajectory analysis. Rice black-streaked dwarf virus, whose vector is L. striatellus, has recently re-emerged in eastern China, and the evidence for overseas migrations of the virus, just like the RSV’s migrations, has been given. A method of predicting the overseas migration of L. striatellus has been developed by Japanese, Chinese, and Korean institutes. An evaluation of the prediction showed that this method properly predicted migration events that occurred in East Asia from 2008 to 2011. Southern rice black-streaked dwarf virus (SRBSDV was first found in Guangdong province. Its vector is S. furcifera. An outbreak of SRBSDV occurred in southern China in 2009 and spread to Vietnam the same year. This disease and virus were also found in Japan in 2010. The epidemic triggered many migration studies to investigate concrete spring-summer migration routes in China, and the addition of migration sources for early arrivals in

Robustness of airline route networks

Science.gov (United States)

Lordan, Oriol; Sallan, Jose M.; Escorihuela, Nuria; Gonzalez-Prieto, David

2016-03-01

Airlines shape their route network by defining their routes through supply and demand considerations, paying little attention to network performance indicators, such as network robustness. However, the collapse of an airline network can produce high financial costs for the airline and all its geographical area of influence. The aim of this study is to analyze the topology and robustness of the network route of airlines following Low Cost Carriers (LCCs) and Full Service Carriers (FSCs) business models. Results show that FSC hubs are more central than LCC bases in their route network. As a result, LCC route networks are more robust than FSC networks.

A multicast tree aggregation algorithm in wavelength-routed WDM networks

Science.gov (United States)

Cheng, Hsu-Chen; Kuo, Chin-Chun; Lin, Frank Y.

2005-02-01

Wavelength division multiplexing (WDM) has been considered a promising transmission technology in optical communication networks. With the continuous advance in optical technology, WDM network will play an important role in wide area backbone networks. Optical wavelength switching, compared with optical packet switching, is a more mature and more cost-effective choice for optical switching technologies. Besides, the technology of time division multiplexing in optical communication networks has been working smoothly for a long time. In the proposed research, the problem of multicast groups aggregation and multicast routing and wavelength assignment in wavelength-routed WDM network is studied. The optical cross connect switches in the problem are assumed to have limited optical multicast/splitting and TDM functionalities. Given the physical network topology and capacity, the objective is to maximize the total revenue by means of utmost merging multicast groups into larger macro-groups. The groups in the same macro-group will share a multicast tree to conduct data transmission. The problem is formulated as an optimization problem, where the objective function is to maximize the total revenue subject to capacity constraints of components in the optical network, wavelength continuity constraints, and tree topology constraints. The decision variables in the formulations include the merging results between groups, multicast tree routing assignment and wavelength assignment. The basic approach to the algorithm development for this model is Lagrangean relaxation in conjunction with a number of optimization techniques. In computational experiments, the proposed algorithms are evaluated on different network topologies and perform efficiently and effectively according to the experiment results.

Migration challenges among Zimbabwean refugees before, during and post arrival in South Africa.

Science.gov (United States)

Idemudia, Erhabor Sunday; Williams, John K; Wyatt, Gail E

2013-01-01

Zimbabweans are immigrating to South Africa with a commonly cited reason being economic opportunities. Prospects of finding employment may be a significant reason to leave behind family, friends, and community, sources that buffer and offer social support against life's challenges. Currently, there is a dearth of research examining the motivators for Zimbabweans immigrating and the experiences encountered along the way and after arrival in South Africa. Such research is essential as large numbers of Zimbabweans may be at risk for emotional and physical trauma during this process. Two gender specific focus group discussions, each lasting 90-minutes and consisting of homeless Zimbabwean refugees, were conducted in the Limpopo Province of South Africa. A semi-structured interview assessed for experiences in and reasons for leaving Zimbabwe, as well as experiences en-route and within South Africa. Discussions were audio-recorded, transcribed, and analyzed using consensual qualitative research and a constant comparison qualitative method. Three temporal themes were identified and included challenges and trauma experienced in Zimbabwe (pre-migration), during the immigration journey (mid-migration), and upon arrival in South Africa (post-migration). While there were some experiential differences, Zimbabwean men and women shared numerous traumatic commonalities. In addition to the themes, three subthemes contributing to reasons for leaving Zimbabwe, two subthemes of negative and traumatic experiences incurred mid-migration, and two post-migration subthemes of challenges were identified. Despite the difficulties encountered in their homeland, newly arrived Zimbabweans in South Africa may be exchanging old struggles for a new array of foreign and traumatic challenges. Reasons to immigrate and the psychological and physical toll of migration exacted at the individual and community levels are discussed. Recommendations advocating for culturally congruent mental health research

The potential of fruit trees to enhance converted habitats for migrating birds in southern Mexico

Science.gov (United States)

Foster, M.S.

2007-01-01

Migration routes used by Nearctic migrant birds can cover great distances; they also differ among species, within species, and between years and seasons. As a result, migration routes for an entire migratory avifauna can encompass broad geographic areas, making it impossible to protect continuous stretches of habitat sufficient to connect the wintering and breeding grounds for most species. Consequently, ways to enhance habitats converted for human use (i.e. for pasture, crop cultivation, human settlement) as stopover sites for migrants are especially important. Shelterbelts around pastures and fields, if planted with species targeted to support migrant (and resident) bird species that naturally occupy mature forest habitats and that are at least partially frugivorous, could be a powerful enhancement tool for such species, if the birds will enter the converted areas to feed. I tested this approach for Nearctic migrant birds during the spring migration through an area in Chiapas, Mexico. Mature forest tree species whose fruits are eaten by birds were surveyed. Based on life form, crop size and fruit characteristics, I selected three tree species for study: Cymbopetalum mayanum (Annonaceae), Bursera simaruba (Burseraceae) and Trophis racemosa (Moraceae). I compared the use of fruits of these species by migrants and residents in forest with their use of the fruits of isolated individuals of the same species in pasture and cropland. All three plant species were useful for enhancing converted habitats for forest-occupying spring migrants, although species differed in the degree to which they entered disturbed areas to feed on the fruits. These tree species could probably enhance habitats for migrants at sites throughout the natural geographic ranges of the plants; in other geographic areas for other target bird groups, other tree species might be more appropriate.

Sex-related dietary changes of Portuguese university students after migration to London, UK

OpenAIRE

Santos, S.; Vilela, S.; Padrão, P.; Caraher, M.

2015-01-01

Aim: To assess the changes in eating habits and food choice motives of Portuguese university students after migration to London, according to sex.\\ud \\ud Methods: Fifty-five Portuguese university students (52.7% female) from 12 randomly selected London universities underwent a face-to-face interview. Trained interviewers administered a structured questionnaire comprising questions on socio-demographic characteristics, the frequency of consumption of selected food and beverage items, and the m...

Factors affecting route selection and survival of steelhead kelts at Snake River dams in 2012 and 2013

Energy Technology Data Exchange (ETDEWEB)

Harnish, Ryan A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Colotelo, Alison H. A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Li, Xinya [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fu, Tao [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Ham, Kenneth D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Deng, Zhiqun [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Green, Ethan D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2015-03-31

In 2012 and 2013, Pacific Northwest National Laboratory (PNNL) conducted a study that summarized the passage route proportions and route-specific survival rates of steelhead kelts that passed through Federal Columbia River Power System (FCRPS) dams. To accomplish this, a total of 811 steelhead kelts were tagged with Juvenile Salmon Acoustic Telemetry System (JSATS) transmitters. Acoustic receivers, both autonomous and cabled, were deployed throughout the FCRPS to monitor the downstream movements of tagged kelts. Kelts were also tagged with passive integrated transponder tags to monitor passage through juvenile bypass systems (JBS) and detect returning fish. The current study evaluated data collected in 2012 and 2013 to identify environmental, temporal, operational, individual, and behavioral variables that were related to forebay residence time, route of passage, and survival of steelhead kelts at FCRPS dams on the Snake River. Multiple approaches, including 3-D tracking, bivariate and multivariable regression modeling, and decision tree analyses were used to identify the environmental, temporal, operational, individual, and behavioral variables that had the greatest effect on forebay residence time, route of passage, and route-specific and overall dam passage survival probabilities for tagged kelts at Lower Granite (LGR), Little Goose (LGS), and Lower Monumental (LMN) dams. In general, kelt behavior and discharge appeared to work independently to affect forebay residence times. Kelt behavior, primarily approach location, migration depth, and “searching” activities in the forebay, was found to have the greatest influence on their route of passage. The condition of kelts was the single most important factor affecting their survival. The information gathered in this study may be used by dam operators and fisheries managers to identify potential management actions to improve in-river survival of kelts or collection methods for kelt reconditioning programs to aid

A floating bridge disrupts seaward migration and increases mortality of steelhead smolts in Hood Canal, Washington state.

Directory of Open Access Journals (Sweden)

Megan Moore

Full Text Available Habitat modifications resulting from human transportation and power-generation infrastructure (e.g., roads, dams, bridges can impede movement and alter natural migration patterns of aquatic animal populations, which may negatively affect survival and population viability. Full or partial barriers are especially problematic for migratory species whose life histories hinge on habitat connectivity.The Hood Canal Bridge, a floating structure spanning the northern outlet of Hood Canal in Puget Sound, Washington, extends 3.6 meters underwater and forms a partial barrier for steelhead migrating from Hood Canal to the Pacific Ocean. We used acoustic telemetry to monitor migration behavior and mortality of steelhead smolts passing four receiver arrays and several single receivers within the Hood Canal, Puget Sound, and Strait of Juan de Fuca. Twenty-seven mortality events were detected within the vicinity of the Hood Canal Bridge, while only one mortality was recorded on the other 325 receivers deployed throughout the study area. Migrating steelhead smolts were detected at the Hood Canal Bridge array with greater frequency, on more receivers, and for longer durations than smolts migrating past three comparably configured arrays. Longer migration times and paths are likely to result in a higher density of smolts near the bridge in relation to other sites along the migration route, possibly inducing an aggregative predator response to steelhead smolts.This study provides strong evidence of substantial migration interference and increased mortality risk associated with the Hood Canal Bridge, and may partially explain low early marine survival rates observed in Hood Canal steelhead populations. Understanding where habitat modifications indirectly increase predation pressures on threatened populations helps inform potential approaches to mitigation.

A floating bridge disrupts seaward migration and increases mortality of steelhead smolts in Hood Canal, Washington state.

Science.gov (United States)

Moore, Megan; Berejikian, Barry A; Tezak, Eugene P

2013-01-01

Habitat modifications resulting from human transportation and power-generation infrastructure (e.g., roads, dams, bridges) can impede movement and alter natural migration patterns of aquatic animal populations, which may negatively affect survival and population viability. Full or partial barriers are especially problematic for migratory species whose life histories hinge on habitat connectivity. The Hood Canal Bridge, a floating structure spanning the northern outlet of Hood Canal in Puget Sound, Washington, extends 3.6 meters underwater and forms a partial barrier for steelhead migrating from Hood Canal to the Pacific Ocean. We used acoustic telemetry to monitor migration behavior and mortality of steelhead smolts passing four receiver arrays and several single receivers within the Hood Canal, Puget Sound, and Strait of Juan de Fuca. Twenty-seven mortality events were detected within the vicinity of the Hood Canal Bridge, while only one mortality was recorded on the other 325 receivers deployed throughout the study area. Migrating steelhead smolts were detected at the Hood Canal Bridge array with greater frequency, on more receivers, and for longer durations than smolts migrating past three comparably configured arrays. Longer migration times and paths are likely to result in a higher density of smolts near the bridge in relation to other sites along the migration route, possibly inducing an aggregative predator response to steelhead smolts. This study provides strong evidence of substantial migration interference and increased mortality risk associated with the Hood Canal Bridge, and may partially explain low early marine survival rates observed in Hood Canal steelhead populations. Understanding where habitat modifications indirectly increase predation pressures on threatened populations helps inform potential approaches to mitigation.

Exposure to Traumatic Experiences Among Asylum Seekers from Eritrea and Sudan During Migration to Israel.

Science.gov (United States)

Nakash, Ora; Langer, Benjamin; Nagar, Maayan; Shoham, Shahar; Lurie, Ido; Davidovitch, Nadav

2015-08-01

Little is known about the experiences of displaced individuals en route to destination countries. We investigated the reported prevalence of exposure to traumatic experiences during migration among a consecutive sample of adult asylum seekers (n = 895 Eritrean, n = 149 Sudanese) who sought health services in the Physicians for Human Rights Open-Clinic in Israel. Percentage of Eritrean and Sudanese men and women who reported witnessing violence (Eritrea: men: 41.3 %, women: 29.3 %; Sudan: men: 16.8 %, women: 22.2 %) and/or being a victim of violence (Eritrea: men: 56.0 %, Women: 34.9 %; Sudan: men: 51.9 % women: 44.4 %) during migration varied by gender and country of origin. Findings highlight the need for a well-coordinated international cooperation to document and prevent these transgressions.

Airport choice model in multiple airport regions

Directory of Open Access Journals (Sweden)

Claudia Muñoz

2017-02-01

Full Text Available Purpose: This study aims to analyze travel choices made by air transportation users in multi airport regions because it is a crucial component when planning passenger redistribution policies. The purpose of this study is to find a utility function which makes it possible to know the variables that influence users’ choice of the airports on routes to the main cities in the Colombian territory. Design/methodology/approach: This research generates a Multinomial Logit Model (MNL, which is based on the theory of maximizing utility, and it is based on the data obtained on revealed and stated preference surveys applied to users who reside in the metropolitan area of Aburrá Valley (Colombia. This zone is the only one in the Colombian territory which has two neighboring airports for domestic flights. The airports included in the modeling process were Enrique Olaya Herrera (EOH Airport and José María Córdova (JMC Airport. Several structure models were tested, and the MNL proved to be the most significant revealing the common variables that affect passenger airport choice include the airfare, the price to travel the airport, and the time to get to the airport. Findings and Originality/value: The airport choice model which was calibrated corresponds to a valid powerful tool used to calculate the probability of each analyzed airport of being chosen for domestic flights in the Colombian territory. This is done bearing in mind specific characteristic of each of the attributes contained in the utility function. In addition, these probabilities will be used to calculate future market shares of the two airports considered in this study, and this will be done generating a support tool for airport and airline marketing policies.

An overview of smart grid routing algorithms

Science.gov (United States)

Wang, Junsheng; OU, Qinghai; Shen, Haijuan

2017-08-01

This paper summarizes the typical routing algorithm in smart grid by analyzing the communication business and communication requirements of intelligent grid. Mainly from the two kinds of routing algorithm is analyzed, namely clustering routing algorithm and routing algorithm, analyzed the advantages and disadvantages of two kinds of typical routing algorithm in routing algorithm and applicability.

Family migration and employment: the importance of migration history and gender.

Science.gov (United States)

Bailey, A J; Cooke, T J

1998-01-01

"This article uses event history data to specify a model of employment returns to initial migration, onward migration, and return migration among newly married persons in the U.S. Husbands are more likely to be full-time employed than wives, and being a parent reduces the employment odds among married women. Employment returns to repeated migration differ by gender, with more husbands full-time employed after onward migration and more wives full-time employed after return migration events. We interpret these empirical findings in the context of family migration theory, segmented labor market theory, and gender-based responsibilities." Data are from the National Longitudinal Survey of Youth from 1979 to 1991. excerpt

A preference for migration

OpenAIRE

Stark, Oded

2007-01-01

At least to some extent migration behavior is the outcome of a preference for migration. The pattern of migration as an outcome of a preference for migration depends on two key factors: imitation technology and migration feasibility. We show that these factors jointly determine the outcome of a preference for migration and we provide examples that illustrate how the prevalence and transmission of a migration-forming preference yield distinct migration patterns. In particular, the imitation of...

Goliath catfish spawning in the far western Amazon confirmed by the distribution of mature adults, drifting larvae and migrating juveniles.

Science.gov (United States)

Barthem, Ronaldo B; Goulding, Michael; Leite, Rosseval G; Cañas, Carlos; Forsberg, Bruce; Venticinque, Eduardo; Petry, Paulo; Ribeiro, Mauro L de B; Chuctaya, Junior; Mercado, Armando

2017-02-06

We mapped the inferred long-distance migrations of four species of Amazonian goliath catfishes (Brachyplatystoma rousseauxii, B. platynemum, B. juruense and B. vaillantii) based on the presence of individuals with mature gonads and conducted statistical analysis of the expected long-distance downstream migrations of their larvae and juveniles. By linking the distribution of larval, juvenile and mature adult size classes across the Amazon, the results showed: (i) that the main spawning regions of these goliath catfish species are in the western Amazon; (ii) at least three species-B. rousseauxii, B. platynemum, and B. juruense-spawn partially or mainly as far upstream as the Andes; (iii) the main spawning area of B. rousseauxii is in or near the Andes; and (iv) the life history migration distances of B. rousseauxii are the longest strictly freshwater fish migrations in the world. These results provide an empirical baseline for tagging experiments, life histories extrapolated from otolith microchemistry interpretations and other methods to establish goliath catfish migratory routes, their seasonal timing and possible return (homing) to western headwater tributaries where they were born.

Southern states' routing agency report

International Nuclear Information System (INIS)

1989-02-01

The Southern states' routing agency report is a compendium of 16-southern states' routing programs relative to the transportation of high-level radioactive materials. The report identifies the state-designated routing agencies as defined under 49 Code of Federal Regulations (CFR) Part 171 and provides a reference to the source ad scope of the agencies' rulemaking authority. Additionally, the state agency and contact designated by the state's governor to receive advance notification and shipment routing information under 10 CFR Parts 71 and 73 are also listed

Southern States' Routing Agency Report

International Nuclear Information System (INIS)

1990-03-01

The Southern States' Routing Agency Report is a compendium of 16-southern states' routing program for the transportation of high-level radioactive materials. The report identifies the state-designated routing agencies as defined under 49 Code of Federal Regulations (CFR) Part 171 and provides a reference to the source and scope of the agencies' rulemaking authority. Additionally, the state agency and contact designated by the state's governor to receive advance notification and shipment routing information under 10 CFR Parts 71 and 73 are also listed

Research on Large-Scale Road Network Partition and Route Search Method Combined with Traveler Preferences

Directory of Open Access Journals (Sweden)

De-Xin Yu

2013-01-01

Full Text Available Combined with improved Pallottino parallel algorithm, this paper proposes a large-scale route search method, which considers travelers’ route choice preferences. And urban road network is decomposed into multilayers effectively. Utilizing generalized travel time as road impedance function, the method builds a new multilayer and multitasking road network data storage structure with object-oriented class definition. Then, the proposed path search algorithm is verified by using the real road network of Guangzhou city as an example. By the sensitive experiments, we make a comparative analysis of the proposed path search method with the current advanced optimal path algorithms. The results demonstrate that the proposed method can increase the road network search efficiency by more than 16% under different search proportion requests, node numbers, and computing process numbers, respectively. Therefore, this method is a great breakthrough in the guidance field of urban road network.

Load Balancing Routing with Bounded Stretch

Directory of Open Access Journals (Sweden)

Chen Siyuan

2010-01-01

Full Text Available Routing in wireless networks has been heavily studied in the last decade. Many routing protocols are based on classic shortest path algorithms. However, shortest path-based routing protocols suffer from uneven load distribution in the network, such as crowed center effect where the center nodes have more load than the nodes in the periphery. Aiming to balance the load, we propose a novel routing method, called Circular Sailing Routing (CSR, which can distribute the traffic more evenly in the network. The proposed method first maps the network onto a sphere via a simple stereographic projection, and then the route decision is made by a newly defined "circular distance" on the sphere instead of the Euclidean distance in the plane. We theoretically prove that for a network, the distance traveled by the packets using CSR is no more than a small constant factor of the minimum (the distance of the shortest path. We also extend CSR to a localized version, Localized CSR, by modifying greedy routing without any additional communication overhead. In addition, we investigate how to design CSR routing for 3D networks. For all proposed methods, we conduct extensive simulations to study their performances and compare them with global shortest path routing or greedy routing in 2D and 3D wireless networks.

Guidelines for selecting preferred highway routes for highway-route-controlled quantity shipments of radioactive materials

International Nuclear Information System (INIS)

1989-01-01

The document presents guidelines for use by State officials in selecting preferred routes for highway route controlled quantity shipments of radioactive materials. A methodology for analyzing and comparing safety factors of alternative routes is described. Technical information on the impacts of radioactive material transportation needed to apply the methodology is also presented. Application of the methodology will identify the route (or set of routes) that minimizes the radiological impacts from shipments of these radioactive materials within a given State. Emphasis in the document is on practical application of the methodology. Some details of the derivation of the methods and data are presented in the appendices. All references in the body of the report can be found listed in the Bibliography (Appendix F)

Choice certainty in Discrete Choice Experiments

DEFF Research Database (Denmark)

Uggeldahl, Kennet Christian; Jacobsen, Catrine; Lundhede, Thomas

2016-01-01

In this study, we conduct a Discrete Choice Experiment (DCE) using eye tracking technology to investigate if eye movements during the completion of choice sets reveal information about respondents’ choice certainty. We hypothesise that the number of times that respondents shift their visual...

When do letter features migrate? A boundary condition for feature-integration theory.

Science.gov (United States)

Butler, B E; Mewhort, D J; Browse, R A

1991-01-01

Feature-integration theory postulates that a lapse of attention will allow letter features to change position and to recombine as illusory conjunctions (Treisman & Paterson, 1984). To study such errors, we used a set of uppercase letters known to yield illusory conjunctions in each of three tasks. The first, a bar-probe task, showed whole-character mislocations but not errors based on feature migration and recombination. The second, a two-alternative forced-choice detection task, allowed subjects to focus on the presence or absence of subletter features and showed illusory conjunctions based on feature migration and recombination. The third was also a two-alternative forced-choice detection task, but we manipulated the subjects' knowledge of the shape of the stimuli: In the case-certain condition, the stimuli were always in uppercase, but in the case-uncertain condition, the stimuli could appear in either upper- or lowercase. Subjects in the case-certain condition produced illusory conjunctions based on feature recombination, whereas subjects in the case-uncertain condition did not. The results suggest that when subjects can view the stimuli as feature groups, letter features regroup as illusory conjunctions; when subjects encode the stimuli as letters, whole items may be mislocated, but subletter features are not. Thus, illusory conjunctions reflect the subject's processing strategy, rather than the architecture of the visual system.

Japanese migration in contemporary Japan: economic segmentation and interprefectural migration.

Science.gov (United States)

Fukurai, H

1991-01-01

This paper examines the economic segmentation model in explaining 1985-86 Japanese interregional migration. The analysis takes advantage of statistical graphic techniques to illustrate the following substantive issues of interregional migration: (1) to examine whether economic segmentation significantly influences Japanese regional migration and (2) to explain socioeconomic characteristics of prefectures for both in- and out-migration. Analytic techniques include a latent structural equation (LISREL) methodology and statistical residual mapping. The residual dispersion patterns, for instance, suggest the extent to which socioeconomic and geopolitical variables explain migration differences by showing unique clusters of unexplained residuals. The analysis further points out that extraneous factors such as high residential land values, significant commuting populations, and regional-specific cultures and traditions need to be incorporated in the economic segmentation model in order to assess the extent of the model's reliability in explaining the pattern of interprefectural migration.

Ways to improve the environmental conditions of their buses in operation on passenger routes of cities

Directory of Open Access Journals (Sweden)

Melnychuk S.V.

2017-04-01

Full Text Available The results of studies on operational and environmental parameters buses used on bus routes Zhitomir city. It uses statistical methods for determining the intensity of traffic, passenger traffic and ecology in traffic. To assess the environmental chosen stop with the greatest intensity of traffic, which is the probability of accumulation of pollution transport emissions that exceed permissible limits. Calculation of environmental pollution emission route for vehicles made stops street «Str. Hundreds of Heaven» «CUM», «vul. Hlibna» on the main trunk street Kievska. Results obtained environmental field experiments compared with the data defined calculation methods, based on the proposed use appropriate operational vehicles. The conclusions that indicate the seriousness of the problem and the urgency to address it. The system of environmental safety and road safety in Zhitomir requires significant improvements due to the increased quantities bus vehicles plying city routes. Recommendations to improve the ecological condition of intersections can be developed through the optimization of traffic using buses with environmentally improved operating parameters. Keywords: environmental and operational parameters; ecological safety; environmental assessment; intensity of traffic; passenger traffic; environmental conditions; operation; bus choice; stop.

Strategies for Selecting Routes through Real-World Environments: Relative Topography, Initial Route Straightness, and Cardinal Direction.

Directory of Open Access Journals (Sweden)

Tad T Brunyé

Full Text Available Previous research has demonstrated that route planners use several reliable strategies for selecting between alternate routes. Strategies include selecting straight rather than winding routes leaving an origin, selecting generally south- rather than north-going routes, and selecting routes that avoid traversal of complex topography. The contribution of this paper is characterizing the relative influence and potential interactions of these strategies. We also examine whether individual differences would predict any strategy reliance. Results showed evidence for independent and additive influences of all three strategies, with a strong influence of topography and initial segment straightness, and relatively weak influence of cardinal direction. Additively, routes were also disproportionately selected when they traversed relatively flat regions, had relatively straight initial segments, and went generally south rather than north. Two individual differences, extraversion and sense of direction, predicted the extent of some effects. Under real-world conditions navigators indeed consider a route's initial straightness, cardinal direction, and topography, but these cues differ in relative influence and vary in their application across individuals.

Impacts of an underwater high voltage DC power cable on fish migration movements in the San Francisco Bay.

Science.gov (United States)

Wyman, M. T.; Kavet, R.; Klimley, A. P.

2016-02-01

There is an increasingly strong interest on a global scale in offshore renewable energy production and transportation. However, there is concern that the electromagnetic fields (EMF) produced by these underwater cables may alter the behavior and physiology of marine species. Despite this concern, few studies have investigated these effects in free-living species. In 2009, a 85 km long high-voltage DC (HVDC) power cable was placed within the San Francisco Bay, running parallel, then perpendicular to, the migration route of anadromous species moving from the inland river system to the oceans. In this study, we assess the impacts of this HVDC cable on the migration behaviors of EMF-sensitive fish, including juvenile salmonids (Chinook salmon, Oncorhynchus tshawytscha, and steelhead trout, Oncorhynchus mykiss) and adult green sturgeon, Acipenser medirostris. Acoustic telemetry techniques were used to track fish migration movements through the San Francisco Bay both before and after the cable was activated; individuals implanted with acoustic transmitters were detected on cross-channel hydrophone arrays at key locations in the system. Magnetic fields were surveyed and mapped at these locations using a transverse gradiometer, and models of the cable's magnetic field were developed that closely matched the empirically measured values. Here, we present our analyses on the relationships between migration-related behavioral metrics (e.g., percent of successful migrations, duration of migration, time spent near vs. far from cable location, etc.) and environmental parameters, such as cable activation and load level, local magnetic field levels, depth, and currents.

Routing and scheduling problems

DEFF Research Database (Denmark)

Reinhardt, Line Blander

couple of decades. To deliver competitive service and price, transportation today needs to be cost effective. A company requiring for things to be shipped will aim at having the freight shipped as cheaply as possible while often satisfying certain time constraints. For the transportation company......, the effectiveness of the network is of importance aiming at satisfying as many costumer demands as possible at a low cost. Routing represent a path between locations such as an origin and destination for the object routed. Sometimes routing has a time dimension as well as the physical paths. This may...... set cost making the cost of the individual vehicle routes inter-dependant. Depending on the problem type, the size of the problems and time available for solving, different solution methods can be applicable. In this thesis both heuristic methods and several exact methods are investigated depending...

Intelligent routing protocol for ad hoc wireless network

Science.gov (United States)

Peng, Chaorong; Chen, Chang Wen

2006-05-01

A novel routing scheme for mobile ad hoc networks (MANETs), which combines hybrid and multi-inter-routing path properties with a distributed topology discovery route mechanism using control agents is proposed in this paper. In recent years, a variety of hybrid routing protocols for Mobile Ad hoc wireless networks (MANETs) have been developed. Which is proactively maintains routing information for a local neighborhood, while reactively acquiring routes to destinations beyond the global. The hybrid protocol reduces routing discovery latency and the end-to-end delay by providing high connectivity without requiring much of the scarce network capacity. On the other side the hybrid routing protocols in MANETs likes Zone Routing Protocol still need route "re-discover" time when a route between zones link break. Sine the topology update information needs to be broadcast routing request on local zone. Due to this delay, the routing protocol may not be applicable for real-time data and multimedia communication. We utilize the advantages of a clustering organization and multi-routing path in routing protocol to achieve several goals at the same time. Firstly, IRP efficiently saves network bandwidth and reduces route reconstruction time when a routing path fails. The IRP protocol does not require global periodic routing advertisements, local control agents will automatically monitor and repair broke links. Secondly, it efficiently reduces congestion and traffic "bottlenecks" for ClusterHeads in clustering network. Thirdly, it reduces significant overheads associated with maintaining clusters. Fourthly, it improves clusters stability due to dynamic topology changing frequently. In this paper, we present the Intelligent Routing Protocol. First, we discuss the problem of routing in ad hoc networks and the motivation of IRP. We describe the hierarchical architecture of IRP. We describe the routing process and illustrate it with an example. Further, we describe the control manage

Risk assessment of alternative proliferation routes

International Nuclear Information System (INIS)

Ahmed, S.; Husseiny, A.A.

1982-01-01

Multi-Attribute Decision Theory is applied to rank II alternative routes to nuclear proliferation in order of difficulty in acquiring nuclear weapons by nonnuclear countries. The method is based on reducing the various variables affecting the decision to a single function providing a measure for the proliferation route. The results indicate that the most difficult route to obtain atomic weapons is through nuclear power reactors, specifically the liquid-metal fast breeder reactor, heavy water Canada deuterium uranium reactor, and light water reactors such as boiling water and pressurized water reactors. The easiest routes are supercritical centrifuge isotope separation, laser isotope separation, and research reactor. However, nonnuclear routes available that result in substantial damage to life and property are easier than any nuclear route

The Globalisation of migration

OpenAIRE

Milan Mesić

2002-01-01

The paper demonstrates that contemporary international migration is a constitutive part of the globalisation process. After defining the concepts of globalisation and the globalisation of migration, the author discusses six key themes, linking globalisation and international migration (“global cities”, the scale of migration; diversification of migration flows; globalisation of science and education; international migration and citizenship; emigrant communities and new identities). First, in ...

The Effect of Tuition Fees on Student Enrollment and Location Choice: Interregional Migration, Border Effects and Gender Differences

DEFF Research Database (Denmark)

Alecke, Bjoern; Burgard, Claudia; Mitze, Timo

This paper investigates the effects of tuition fees on the university enrollment and location decision of high school graduates in Germany. After a Federal Constitutional Court decision in 2005, 7 out of 16 German federal states introduced tuition fees for higher education. In the empirical...... analysis, we use the variation over time and across regions in this institutional change in order to isolate the causal effect of tuition fees on student enrollment and migration. Controlling for a range of regional- and university-specific effects, our results from Difference-in-Differences estimations...... show that there is generally no effect of tuition fees on internal enrollment rates. However, we find a redirecting effect on first-year students' migratory behavior as indicated by a significant drop in the gross in-migration rates in fee-charging states. Further, our results point at a stronger...

Transportation Routing Analysis Geographic Information System -- TRAGIS, progress on improving a routing tool

International Nuclear Information System (INIS)

Johnson, P.E.; Lester, P.B.

1998-05-01

The Transportation Routing Analysis Geographic Information System (TRAGIS) model provides a useful tool to calculate and analyze transportation routes for radioactive materials within the continental US. This paper outlines some of the features available in this model

Collective network routing

Science.gov (United States)

Hoenicke, Dirk

2014-12-02

Disclosed are a unified method and apparatus to classify, route, and process injected data packets into a network so as to belong to a plurality of logical networks, each implementing a specific flow of data on top of a common physical network. The method allows to locally identify collectives of packets for local processing, such as the computation of the sum, difference, maximum, minimum, or other logical operations among the identified packet collective. Packets are injected together with a class-attribute and an opcode attribute. Network routers, employing the described method, use the packet attributes to look-up the class-specific route information from a local route table, which contains the local incoming and outgoing directions as part of the specifically implemented global data flow of the particular virtual network.

Migration and Remittances : Recent Developments and Outlook - Transit Migration

OpenAIRE

World Bank Group

2018-01-01

This Migration and Development Brief reports global trends in migration and remittance flows, as well as developments related to the Global Compact on Migration (GCM), and the Sustainable Development Goal (SDG) indicators for volume of remittances as percentage of gross domestic product (GDP) (SDG indicator 17.3.2), reducing remittance costs (SDG indicator 10.c.1) and recruitment costs (SD...

Fuel load and flight ranges of blackcaps Sylvia atricapilla in northern Iberia during autumn and spring migrations

Directory of Open Access Journals (Sweden)

JUAN ARIZAGA, EMILIO BARBA

2009-12-01

Full Text Available Fuel accumulation, mainly as fatty acids, is one of the main characteristics of migratory birds. Studying to what extent each population or species manages fuel load and how it varies along routes of migration or between seasons (autumn and spring migrations is crucial to our understanding of bird migration strategies. Our aim here was to analyse whether migratory blackcaps Sylvia atricapilla passing through northern Iberia differ in their mean fuel loads, rate of fuel accumulation and 'potential' flight ranges between migration seasons. Blackcaps were mist netted for 4 h-periods beginning at dawn from 16 September to 15 November 2003–2005, and from 1 March to 30 April 2004–2006 in a European Atlantic hedgerow at Loza, northern Iberia. Both fuel load and fuel deposition rate (this latter assessed with difference in body mass of within-season recaptured individuals were higher in autumn than in spring. Possible hypotheses explaining these results could be seasonal-associated variations in food availability (likely lower during spring than during autumn, the fact that a fraction of the migrants captured in spring could breed close to the study area and different selective pressures for breeding and wintering [Current Zoology 55 (6: 401–410, 2009].

Route Scherrer and Route Einstein closed for construction work

CERN Multimedia

2015-01-01

Please note that Route Scherrer will be inaccessible for two and a half months from the beginning of March and that part of Route Einstein will be closed for two weeks from the end of February.   Figure 1. The part of Route Scherrer between Building 510 and Building 53 (see Figure 1) will be closed from the beginning of March until mid-May for civil engineering works.   The superheated water pipes supplying the buildings in this area date back to 1959 and therefore present a significant risk of leakage. In order to ensure the reliable supply of superheated water, and, by extension, heating, to all premises near the Main Building (i.e. Buildings 500, 501, 503, 60, 62, 63 and 64), a new buried service duct will be installed between the basements of Buildings 53 and 61 to house a new superheated water pipe. Figure 2. The following car parks will, however, remain accessible for the duration of the works: the Cèdres car park, the car park for Buildings 4 and 5, and the ca...

Highway route controlled quantity shipment routing reports - An overview

International Nuclear Information System (INIS)

Cashwell, J.W.; Welles, B.W.; Welch, M.J.

1989-01-01

US Department of Transportation (DOT) regulations require a postnotification report from the shipper for all shipments of radioactive materials categorized as a Highway Route Controlled Quantity. These postnotification reports, filed in compliance with 49 CFR 172.203(d), have been compiled by the DOT in a database known as the Radioactive Materials Routing Report (RAMRT) since 1982. The data were sorted by each of its elements to establish historical records and trends of Highway Route Controlled Quantity shipments from 1982 through 1987. Approximately 1520 records in the RAMRT database were compiled for this analysis. Approximately half of the shipments reported for the study period were from the US Department of Energy (DOE) and its contractors, with the others being commercial movements. Two DOE installations, EG and G Idaho and Oak Ridge, accounted for nearly half of the DOE activities. Similarly, almost half of the commercial movements were reported by two vendors, Nuclear Assurance Corporation and Transnuclear, Incorporated. Spent fuel from power and research reactors accounted for approximately half of all shipments

Chieti-Pescara Metropolitan Area: International Migrations, Residential Choices and Economic Deconcentration

Directory of Open Access Journals (Sweden)

Armando Montanari

2006-06-01

Full Text Available The subject of human mobility – with reference to the migratory component – has taken on specific significance during the last decade, particularly with regard to the concept of place. This paper considers the subject in relation to residential and economic deconcentration. The specific point of reference is the metropolitan area of Chieti-Pescara, in the central part of Italy’s Adriatic coast. The research was carried out through quantitative analysis of official data from population censuses and register offices. The results highlight the links between movements of residents and those of firms, in which foreign residents show distinctive behaviour. The residential choices made by foreigners in the area are based on economic reasons and are primarily linked to housing and transport costs. Their communities tend to be concentrated in specific zones of the metropolitan area and in specific districts of the cities, as a consequence of a feeling of belonging and solidarity. Although there are no clear signs of segregation phenomena, the native population tends to avoid mingling with foreigners from marginal countries.

US Hazardous Materials Routes, Geographic WGS84, BTS (2006) [hazardous_material_routes_BTS_2006

Data.gov (United States)

Louisiana Geographic Information Center — The Federal Motor Carrier Safety Administration (FMCSA) Hazardous Material Routes were developed using the 2004 First Edition TIGER/Line files. The routes are...

A MODIFIED ROUTE DISCOVERY APPROACH FOR DYNAMIC SOURCE ROUTING (DSR PROTOCOL IN MOBILE AD-HOC NETWORKS

Directory of Open Access Journals (Sweden)

Alaa Azmi Allahham

2017-02-01

Full Text Available Mobile Ad-hoc networks (MANETs involved in many applications, whether commercial or military because of their characteristics that do not depend on the infrastructure as well as the freedom movement of their elements, but in return has caused this random mobility of the nodes many of the challenges, where the routing is considered one of these challenges. There are many types of routing protocols that operate within MANET networks, which responsible for finding paths between the source and destination nodes with the modernization of these paths which are constantly changing due to the dynamic topology of the network stemming from the constant random movement of the nodes. The DSR (Dynamic Source Routing routing protocol algorithm is one of these routing protocols which consist of two main stages; route discovery and maintenance, where the route discovery algorithm operates based on blind flooding of request messages. blind flooding is considered as the most well known broadcasting mechanism, it is inefficient in terms of communication and resource utilization, which causing increasing the probability of collisions, repeating send several copies of the same message, as well as increasing the delay. Hence, a new mechanism in route discovery stage and in caching the routes in DSR algorithm according to the node's location in the network and the direction of the broadcast is proposed for better performance especially in terms of delay as well as redundant packets rate. The implementation of proposed algorithms showed positive results in terms of delay, overhead, and improve the performance of MANETs in general.

The tyranny of choice: a cross-cultural investigation of maximizing-satisfising effects on well-being

Directory of Open Access Journals (Sweden)

Arne Roets

2012-11-01

Full Text Available The present research investigated the relationship between individual differences in maximizing versus satisficing (i.e., seeking to make the single best choice, rather than a choice that is merely good enough and well-being, in interaction with the society in which an individual lives. Data from three distinct cultural groups (adults, drawn respectively from the U.S. (N=307, Western Europe (N=263, and China (N=218, were analyzed. The results showed that, in societies where choice is abundant (i.e., U.S. and Western Europe, maximizers reported less well-being than satisficers, and this difference was mediated by experienced regret. However, in the non-western society (China, maximizing was unrelated to well-being. Although in China maximizing was associated with more experiences of regret, regret had no substantial relationship to well-being. These patterns also emerged for the individual facets of the maximizing scale, although with a notable difference between the U.S. and Europe for the High Standards facet. It is argued that, in societies where abundant individual choice is highly valued and considered the ultimate route to personal happiness, maximizers' dissatisfaction and regret over imperfect choices is a detrimental factor in well-being, whereas it is a much less crucial determinant of well-being in societies that place less emphasis on choice as the way to happiness.

Route-specific analysis for radioactive materials transportation

International Nuclear Information System (INIS)

1986-01-01

This report addresses a methodology for route-specific analysis, of which route-selection is one aspect. Identification and mitigation of specific hazards along a chosen route is another important facet of route-specific analysis. Route-selection and route-specific mitigation are two tools to be used in minimizing the risk of radioactive materials transportation and promoting public confidence. Other tools exist to improve the safety of transportation under the Nuclear Waste Policy Act. Selection of a transportation mode and other, non-route-specific measures, such as improved driver training and improved cask designs, are additional tools to minimize transportation risk and promote public confidence. This report addresses the route-specific analysis tool and does not attempt to evaluate its relative usefulness as compared to other available tools. This report represents a preliminary attempt to develop a route-specific analysis methodlogy. The Western Interstate Energy Board High-Level Waste Committee has formed a Route-Specific Analysis Task Force which will build upon the methodology proposed in this Staff Report. As western states continue to investigate route-specific analysis issues, it is expected that the methodology will evolve into a more refined product representing the views of a larger group of interested parties in the West

Bellman Ford algorithm - in Routing Information Protocol (RIP)

Science.gov (United States)

Krianto Sulaiman, Oris; Mahmud Siregar, Amir; Nasution, Khairuddin; Haramaini, Tasliyah

2018-04-01

In a large scale network need a routing that can handle a lot number of users, one of the solutions to cope with large scale network is by using a routing protocol, There are 2 types of routing protocol that is static and dynamic, Static routing is manually route input based on network admin, while dynamic routing is automatically route input formed based on existing network. Dynamic routing is efficient used to network extensively because of the input of route automatic formed, Routing Information Protocol (RIP) is one of dynamic routing that uses the bellman-ford algorithm where this algorithm will search for the best path that traversed the network by leveraging the value of each link, so with the bellman-ford algorithm owned by RIP can optimize existing networks.

Irregular Migration flows and human trafficking in the Western Balkan countries: challenges of the covergence of counter-trafficking response

OpenAIRE

Mece, Merita H.

2016-01-01

Irregular migration on the Western Balkan route has marked an unprecedented number during the last five years. Evidence indicates that both, non-European nationals and Western Balkan citizens have been involved in this complex migratory flow being exposed to various risks of human trafficking. But Western Balkan countries are source, transit and destination countries of human trafficking while their states are not well organized to implement a comprehensive and well-coordinated regional respo...

MIGRATION PATTERNS, USE OF STOPOVER AREAS, AND AUSTRAL SUMMER MOVEMENTS OF SWAINSON’S HAWKS

Science.gov (United States)

Kochert, Michael N.; Fuller, Mark R.; Schueck, Linda S.; Bond, Laura; Bechard, Marc J.; Woodbridge, Brian; Holroyd, Geoff; Martell, Mark; Banasch, Ursula

2015-01-01

From 1995–1998, we tracked movements of adult Swainson’s Hawks (Buteo swainsoni) using satellite telemetry to characterize migration, important stopover areas, and austral summer movements. We tagged 46 hawks from July - September on their nesting grounds in seven U.S. states and two Canadian provinces. Swainson’s Hawks basically followed three routes south on a broad front, converged along the east coast of central Mexico, and followed a concentrated corridor to a communal austral summer area in central Argentina. North of 20° N, southward and northward tracks differed little for individuals from east of the Continental Divide but differed greatly (up to 1700 km) for individuals from west of the Continental Divide. Hawks left the breeding grounds mid-August to mid-October; departure dates did not differ by location, year, or sex. South migration lasted 42 to 98 days, and north migration took 51 to 82 days. On south migration, 36% of the Swainson’s Hawks departed the nesting grounds nearly 3 weeks earlier than the other radio marked hawks and made stopovers 9.0 – 26.0 days long in seven separate areas, mainly in the southern Great Plains, southern Arizona and New Mexico, and north-central Mexico. The austral period lasted 76 to 128 days. All Swainson’s Hawks used a core area in central Argentina within 23% of the 738800 km2 austral summer range where they frequently moved long distances (up to 1600 km). Conservation of Swainson’s Hawks must be an international effort that considers habitats used during nesting and non-nesting seasons including migration stopovers. PMID:26380528

Population, migration and urbanization.

Science.gov (United States)

1982-06-01

Despite recent estimates that natural increase is becoming a more important component of urban growth than rural urban transfer (excess of inmigrants over outmigrants), the share of migration in the total population growth has been consistently increasing in both developed and developing countries. From a demographic perspective, the migration process involves 3 elements: an area of origin which the mover leaves and where he or she is considered an outmigrant; the destination or place of inmigration; and the period over which migration is measured. The 2 basic types of migration are internal and international. Internal migration consists of rural to urban migration, urban to urban migration, rural to rural migration, and urban to rural migration. Among these 4 types of migration various patterns or processes are followed. Migration may be direct when the migrant moves directly from the village to the city and stays there permanently. It can be circular migration, meaning that the migrant moves to the city when it is not planting season and returns to the village when he is needed on the farm. In stage migration the migrant makes a series of moves, each to a city closer to the largest or fastest growing city. Temporary migration may be 1 time or cyclical. The most dominant pattern of internal migration is rural urban. The contribution of migration to urbanization is evident. For example, the rapid urbanization and increase in urban growth from 1960-70 in the Republic of Korea can be attributed to net migration. In Asia the largest component of the population movement consists of individuals and groups moving from 1 rural location to another. Recently, because urban centers could no longer absorb the growing number of migrants from other places, there has been increased interest in the urban to rural population redistribution. This reverse migration also has come about due to slower rates of employment growth in the urban centers and improved economic opportunities

Predicting transportation routes for radioactive wastes

International Nuclear Information System (INIS)

Joy, D.S.; Johnson, P.E.; Clarke, D.B.; McGuire, S.C.

1981-01-01

Oak Ridge National Laboratory (ORNL) has been involved in transportation logistics of radioactive wastes as part of the overall waste transportation program. A Spent Fuel Logistics Model (SFLM), was developed to predict overall material balances representing the flow of spent fuel assemblies from reactors to away-from-reactor storage facilities and/or to federal repositories. The transportation requirements to make these shipments are also itemized. The next logical step in the overall transportation project was the development of a set of computer codes which would predict likely transportation routes for waste shipments. Two separate routing models are now operational at ORNL. Routes for truck transport can be estimated with the HIGHWAY program, and rail and barge routes can be predicted with the INTERLINE model. This paper discusses examples of the route estimates and applications of the routing models

Signaling through three chemokine receptors triggers the migration of transplanted neural precursor cells in a model of multiple sclerosis.

Science.gov (United States)

Cohen, Mikhal E; Fainstein, Nina; Lavon, Iris; Ben-Hur, Tamir

2014-09-01

Multiple sclerosis (MS) is a multifocal disease, and precursor cells need to migrate into the multiple lesions in order to exert their therapeutic effects. Therefore, cell migration is a crucial element in regenerative processes in MS, dictating the route of delivery, when cell transplantation is considered. We have previously shown that inflammation triggers migration of multi-potential neural precursor cells (NPCs) into the white matter of experimental autoimmune encephalomyelitis (EAE) rodents, a widely used model of MS. Here we investigated the molecular basis of this attraction. NPCs were grown from E13 embryonic mouse brains and transplanted into the lateral cerebral ventricles of EAE mice. Transplanted NPC migration was directed by three tissue-derived chemokines. Stromal cell-derived factor-1α, monocyte chemo-attractant protein-1 and hepatocyte growth factor were expressed in the EAE brain and specifically in microglia and astrocytes. Their cognate receptors, CXCR4, CCR2 or c-Met were constitutively expressed on NPCs. Selective blockage of CXCR4, CCR2 or c-Met partially inhibited NPC migration in EAE brains. Blocking all three receptors had an additive effect and resulted in profound inhibition of NPC migration, as compared to extensive migration of control NPCs. The inflammation-triggered NPC migration into white matter tracts was dependent on a motile NPC phenotype. Specifically, depriving NPCs from epidermal growth factor (EGF) prevented the induction of glial commitment and a motile phenotype (as indicated by an in vitro motility assay), hampering their response to neuroinflammation. In conclusion, signaling via three chemokine systems accounts for most of the inflammation-induced, tissue-derived attraction of transplanted NPCs into white matter tracts during EAE. Copyright © 2014. Published by Elsevier B.V.

In vivo migration of labeled autologous natural killer cells to liver metastases in patients with colon carcinoma

Directory of Open Access Journals (Sweden)

Satolli Maria A

2006-11-01

Full Text Available Abstract Background Besides being the effectors of native anti-tumor cytotoxicity, NK cells participate in T-lymphocyte responses by promoting the maturation of dendritic cells (DC. Adherent NK (A-NK cells constitute a subset of IL-2-stimulated NK cells which show increased expression of integrins and the ability to adhere to solid surface and to migrate, infiltrate, and destroy cancer. A critical issue in therapy of metastatic disease is the optimization of NK cell migration to tumor tissues and their persistence therein. This study compares localization to liver metastases of autologous A-NK cells administered via the systemic (intravenous, i.v. versus locoregional (intraarterial, i.a. routes. Patients and methods A-NK cells expanded ex-vivo with IL-2 and labeled with 111In-oxine were injected i.a. in the liver of three colon carcinoma patients. After 30 days, each patient had a new preparation of 111In-A-NK cells injected i.v. Migration of these cells to various organs was evaluated by SPET and their differential localization to normal and neoplastic liver was demonstrated after i.v. injection of 99mTc-phytate. Results A-NK cells expressed a donor-dependent CD56+CD16+CD3- (NK or CD56+CD16+CD3+ (NKT phenotype. When injected i.v., these cells localized to the lung before being visible in the spleen and liver. By contrast, localization of i.a. injected A-NK cells was virtually confined to the spleen and liver. Binding of A-NK cells to liver neoplastic tissues was observed only after i.a. injections. Conclusion This unique study design demonstrates that A-NK cells adoptively transferred to the liver via the intraarterial route have preferential access and substantial accumulation to the tumor site.

RSRP: A Robust Secure Routing Protocol in MANET

Directory of Open Access Journals (Sweden)

Sinha Ditipriya

2014-05-01

Full Text Available In this paper, we propose a novel algorithm RSRP to build a robust secure routing protocol in mobile ad-hoc networks (MANETs. This algorithm is based on some basic schemes such as RSA_CRT for encryption and decryption of messages; CRT for safety key generation, Shamir’s secret sharing principle for generation of secure routes. Those routes which are free from any malicious node and which belong to the set of disjoint routes between a source-destination pair are considered as probable routes. Shamir’s secret sharing principle is applied on those probable routes to obtain secure routes. Finally, most trustworthy and stable route is selected among those secure routes. Selection of the final route depends on some criteria of the nodes present in a route e.g.: battery power, mobility and trust value. In addition, complexity of key generation is reduced to a large extent by using RSA-CRT instead of RSA. In turn, the routing becomes less expensive and most secure and robust one. Performance of this routing protocol is then compared with non-secure routing protocols (AODV and DSR, secure routing scheme using secret sharing, security routing protocol using ZRP and SEAD depending on basic characteristics of these protocols. All such comparisons show that RSRP shows better performance in terms of computational cost, end-to-end delay and packet dropping in presence of malicious nodes in the MANET, keeping the overhead in terms of control packets same as other secure routing protocols.

Radon depth migration

International Nuclear Information System (INIS)

Hildebrand, S.T.; Carroll, R.J.

1993-01-01

A depth migration method is presented that used Radon-transformed common-source seismograms as input. It is shown that the Radon depth migration method can be extended to spatially varying velocity depth models by using asymptotic ray theory (ART) to construct wavefield continuation operators. These operators downward continue an incident receiver-array plane wave and an assumed point-source wavefield into the subsurface. The migration velocity model is constrain to have longer characteristic wavelengths than the dominant source wavelength such that the ART approximations for the continuation operators are valid. This method is used successfully to migrate two synthetic data examples: (1) a point diffractor, and (2) a dipping layer and syncline interface model. It is shown that the Radon migration method has a computational advantage over the standard Kirchhoff migration method in that fewer rays are computed in a main memory implementation

Effect of the route of administration on the biodistribution of radioiodinated OV-TL 3 F(ab')2 in experimental ovarian cancer

International Nuclear Information System (INIS)

Tibben, J.G.; Massuger, L.F.A.G.; Boerman, O.C.; Borm, G.F.; Claessens, R.A.M.J.; Corstens, F.H.M.

1994-01-01

The effect of the route administration on the distribution of radioiodinated OV-TL 3 F(ab') 2 was studied in Balb/c female mice with intraperitoneal or subcutaneous ovarian carcinoma xenografts. In the intraperitoneal tumour model in which both ascites and solid tumour deposits were present, intraperitoneal administration resulted in a lower estimated radiation dose to blood as compared with intravenous administration. In this model normalization to equal estimated radiation doses to blood for both routes of administration indicated that a twice as high estimated radiation dose can be guided to solid intraperitoneal tumour deposits following intraperitoneal administration. Evacuation of ascitic tumour cells prior to monoclonal antibody injection further increased the estimated radiation dose to solid intraperitoneal tumour deposits following intraperitoneal delivery. Following simultaneous intravenous and intraperitoneal injection of the monoclonal antibody, tissue uptake showed no relevant differences in the subcutaneous tumour model. Overall, the intraperitoneal route of administration was found to be the best choice for therapeutic delivery of iodine-131 labelled monoclonal antibodies. (orig.)

Vehicle Routing With User Generated Trajectory Data

DEFF Research Database (Denmark)

Ceikute, Vaida; Jensen, Christian S.

Rapidly increasing volumes of GPS data collected from vehicles provide new and increasingly comprehensive insight into the routes that drivers prefer. While routing services generally compute shortest or fastest routes, recent studies suggest that local drivers often prefer routes that are neithe...

A Genetic Algorithm on Inventory Routing Problem

Directory of Open Access Journals (Sweden)

Nevin Aydın

2014-03-01

Full Text Available Inventory routing problem can be defined as forming the routes to serve to the retailers from the manufacturer, deciding on the quantity of the shipment to the retailers and deciding on the timing of the replenishments. The difference of inventory routing problems from vehicle routing problems is the consideration of the inventory positions of retailers and supplier, and making the decision accordingly. Inventory routing problems are complex in nature and they can be solved either theoretically or using a heuristics method. Metaheuristics is an emerging class of heuristics that can be applied to combinatorial optimization problems. In this paper, we provide the relationship between vendor-managed inventory and inventory routing problem. The proposed genetic for solving vehicle routing problem is described in detail.

Theoretical foundations of international migration process studies: analysis of key migration theories development

Directory of Open Access Journals (Sweden)

Shymanska K.V.

2017-03-01

Full Text Available The need for transformation of Ukraine's migration policy based on globalized world development trends and in response to the challenges of European integration transformations causes the need of researching the theoretical and methodological basis of migration studies, and the regulations of existing theories of international migration. The bibliometric analysis of scientific publications on international migration in cites indexes found that the recent researches on these problems acquire interdisciplinary character. It necessitates the transformation of migration study approaches basing on economic, social, institutional theories and concepts synthesis. The article is devoted to the study of theoretical regulations of existing international migration theories in the context of the evolution of scientists’ views on this phenomenon. The author found that the existing theories of international migration should be divided into three categories (microeconomic, macroeconomic, globalizational that contributes to their understanding in the context of implementation possibilities in migrational public administration practice. It allows to determine the theories which should be used for Ukrainian state migration policy constructing and eliminating or reducing the external migration negative effects.

Zone routing in a torus network

Science.gov (United States)

Chen, Dong; Heidelberger, Philip; Kumar, Sameer

2013-01-29

A system for routing data in a network comprising a network logic device at a sending node for determining a path between the sending node and a receiving node, wherein the network logic device sets one or more selection bits and one or more hint bits within the data packet, a control register for storing one or more masks, wherein the network logic device uses the one or more selection bits to select a mask from the control register and the network logic device applies the selected mask to the hint bits to restrict routing of the data packet to one or more routing directions for the data packet within the network and selects one of the restricted routing directions from the one or more routing directions and sends the data packet along a link in the selected routing direction toward the receiving node.

Vertically averaged approaches for CO 2 migration with solubility trapping

KAUST Repository

Gasda, S. E.

2011-05-20

The long-term storage security of injected carbon dioxide (CO2) is an essential component of geological carbon sequestration operations. In the postinjection phase, the mobile CO2 plume migrates in large part because of buoyancy forces, following the natural topography of the geological formation. The primary trapping mechanisms are capillary and solubility trapping, which evolve over hundreds to thousands of years and can immobilize a significant portion of the mobile CO2 plume. However, both the migration and trapping processes are inherently complex, spanning multiple spatial and temporal scales. Using an appropriate model that can capture both large- and small-scale effects is essential for understanding the role of these processes on the long-term storage security of CO2 sequestration operations. Traditional numerical models quickly become prohibitively expensive for the type of large-scale, long-term modeling that is necessary for characterizing the migration and immobilization of CO2 during the postinjection period. We present an alternative modeling option that combines vertically integrated governing equations with an upscaled representation of the dissolution-convection process. With this approach, we demonstrate the effect of different modeling choices for typical large-scale geological systems and show that practical calculations can be performed at the temporal and spatial scales of interest. Copyright 2011 by the American Geophysical Union.

Migration and risk: net migration in marginal ecosystems and hazardous areas

International Nuclear Information System (INIS)

De Sherbinin, Alex; Levy, Marc; Adamo, Susana; MacManus, Kytt; Yetman, Greg; Mara, Valentina; Razafindrazay, Liana; Aichele, Cody; Pistolesi, Linda; Goodrich, Benjamin; Srebotnjak, Tanja

2012-01-01

The potential for altered ecosystems and extreme weather events in the context of climate change has raised questions concerning the role that migration plays in either increasing or reducing risks to society. Using modeled data on net migration over three decades from 1970 to 2000, we identify sensitive ecosystems and regions at high risk of climate hazards that have seen high levels of net in-migration and out-migration over the time period. This paper provides a literature review on migration related to ecosystems, briefly describes the methodology used to develop the estimates of net migration, then uses those data to describe the patterns of net migration for various ecosystems and high risk regions. The study finds that negative net migration generally occurs over large areas, reflecting its largely rural character, whereas areas of positive net migration are typically smaller, reflecting its largely urban character. The countries with largest population such as China and India tend to drive global results for all the ecosystems found in those countries. Results suggest that from 1970 to 2000, migrants in developing countries have tended to move out of marginal dryland and mountain ecosystems and out of drought-prone areas, and have moved towards coastal ecosystems and areas that are prone to floods and cyclones. For North America results are reversed for dryland and mountain ecosystems, which saw large net influxes of population in the period of record. Uncertainties and potential sources of error in these estimates are addressed. (letter)

Capacity Constrained Routing Algorithms for Evacuation Route Planning

National Research Council Canada - National Science Library

Lu, Qingsong; George, Betsy; Shekhar, Shashi

2006-01-01

.... In this paper, we propose a new approach, namely a capacity constrained routing planner which models capacity as a time series and generalizes shortest path algorithms to incorporate capacity constraints...

Migration challenges among Zimbabwean refugees before, during and post arrival in South Africa

Directory of Open Access Journals (Sweden)

Erhabor Sunday Idemudia

2013-01-01

Full Text Available BACKGROUND: Zimbabweans are immigrating to South Africa with a commonly cited reason being economic opportunities. Prospects of finding employment may be a significant reason to leave behind family, friends, and community, sources that buffer and offer social support against life’s challenges. Currently, there is a dearth of research examining the motivators for Zimbabweans immigrating and the experiences encountered along the way and after arrival in South Africa. Such research is essential as large numbers of Zimbabweans may be at risk for emotional and physical trauma during this process. METHODS: Two gender specific focus group discussions, each lasting 90-minutes and consisting of homeless Zimbabwean refugees, were conducted in the Limpopo Province of South Africa. A semi-structured interview assessed for experiences in and reasons for leaving Zimbabwe, as well as experiences en-route and within South Africa. Discussions were audio-recorded, transcribed, and analyzed using consensual qualitative research and a constant comparison qualitative method. RESULTS: Three temporal themes were identified and included challenges and trauma experienced in Zimbabwe (pre-migration, during the immigration journey (mid-migration, and upon arrival in South Africa (post-migration. While there were some experiential differences, Zimbabwean men and women shared numerous traumatic commonalities. In addition to the themes, three subthemes contributing to reasons for leaving Zimbabwe, two subthemes of negative and traumatic experiences incurred mid-migration, and two post-migration subthemes of challenges were identified. CONCLUSIONS: Despite the difficulties encountered in their homeland, newly arrived Zimbabweans in South Africa may be exchanging old struggles for a new array of foreign and traumatic challenges. Reasons to immigrate and the psychological and physical toll of migration exacted at the individual and community levels are discussed

Labour Migrations of Bulgarians from Ukraine to the European Union Today and Tomorrow: Factors and Forecasts

Directory of Open Access Journals (Sweden)

Alexander Ganchev

2011-08-01

Full Text Available Labour migrations from Ukraine to the European Union are closely connected with the issues of interrelations between EU metropolitan countries and their Diasporas in Ukraine. Labour migration developments in independent Ukraine after 1991 have been moving towards their intensification. Migration trends among the Bulgarian Diaspora of South-Western Ukraine gained specific characteristics in the period of the world economic crisis. The enlargement of the EU in 2004 and 2007 led to the transformations in the preferences and choice factors of labour migrants, representatives of the Bulgarian Diaspora, while choosing the destination country in the EU. As a metropolitan country, Bulgaria has focused its policy on attracting its Diaspora groups, seeing them as labour and demographic potential for further development. This point of view is justified in many respects, though metropolitan country efforts must also be directed to the support of the Diaspora and its social, psychological, cultural and linguistic features.

Migratory timing, rate, routes and wintering areas of White-crested Elaenia (Elaenia albiceps chilensis, a key seed disperser for Patagonian forest regeneration.

Directory of Open Access Journals (Sweden)

Susana Patricia Bravo

Full Text Available Migratory animals often play key ecological roles within the communities they visit throughout their annual journeys. As a consequence of the links between biomes mediated by migrants, changes in one biome could affect remote areas in unpredictable ways. Migratory routes and timing of most Neotropical austral migrants, which breed at south temperate latitudes of South America and overwinter closer to or within tropical latitudes of South America, have yet to be described in detail. As a result, our understanding about how these birds provide links between South American biomes is almost non-existent. White-crested Elaenia (Elaenia albiceps chilensis is a long-distance austral migrant that breeds in the Patagonian Forest biome and overwinters in tropical South America. Because this small flycatcher plays a key role in the regeneration of this ecosystem, our objective was to describe the annual cycle of White-crested elaenias to evaluate the degree of migratory connectivity between breeding and wintering areas and therefore to determine if there are specific biomes of northern South America linked by elaenias to Patagonian forests. Fifteen individuals were successfully tracked throughout a complete migration cycle using miniature light-level geolocators. All individuals resided and moved through the same general regions. During fall (March-April-May, elaenias were located in the Caatinga and the Atlantic Forest biomes, from Rio de Janeiro to the region near Salvador da Bahia, Brazil. During winter (June-July-Aug., birds were located further inland, within the Cerrado biome. Birds used three different routes during fall migration. Our results indicate that some individuals use a direct route, flying between 500-600 km/day, crossing desert and grasslands, while others took a detour, flying 100-200 km/day through forested areas with refueling opportunities. All birds used the Yunga forest during spring migration, with ten out of 15 individuals

Neuronal Migration and Neuronal Migration Disorder in Cerebral Cortex

OpenAIRE

SUN, Xue-Zhi; TAKAHASHI, Sentaro; GUI, Chun; ZHANG, Rui; KOGA, Kazuo; NOUYE, Minoru; MURATA, Yoshiharu

2002-01-01

Neuronal cell migration is one of the most significant features during cortical development. After final mitosis, neurons migrate from the ventricular zone into the cortical plate, and then establish neuronal lamina and settle onto the outermost layer, forming an "inside-out" gradient of maturation. Neuronal migration is guided by radial glial fibers and also needs proper receptors, ligands, and other unknown extracellular factors, requests local signaling (e.g. some emitted by the Cajal-Retz...

Entanglement-Gradient Routing for Quantum Networks.

Science.gov (United States)

Gyongyosi, Laszlo; Imre, Sandor

2017-10-27

We define the entanglement-gradient routing scheme for quantum repeater networks. The routing framework fuses the fundamentals of swarm intelligence and quantum Shannon theory. Swarm intelligence provides nature-inspired solutions for problem solving. Motivated by models of social insect behavior, the routing is performed using parallel threads to determine the shortest path via the entanglement gradient coefficient, which describes the feasibility of the entangled links and paths of the network. The routing metrics are derived from the characteristics of entanglement transmission and relevant measures of entanglement distribution in quantum networks. The method allows a moderate complexity decentralized routing in quantum repeater networks. The results can be applied in experimental quantum networking, future quantum Internet, and long-distance quantum communications.

Japanese Migration and the Americas: An Introduction to the Study of Migration.

Science.gov (United States)

Mukai, Gary; Brunette, Rachel

This curriculum module introduces students to the study of migration, including a brief overview of some categories of migration and reasons why people migrate. As a case study, the module uses the Japanese migration experience in the United States, Peru, Brazil, Canada, Mexico, Argentina, Bolivia, and Paraguay. The module introduces students to…

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...

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...

Routed planar networks

Directory of Open Access Journals (Sweden)

David J. Aldous

2016-04-01

Full Text Available Modeling a road network as a planar graph seems very natural. However, in studying continuum limits of such networks it is useful to take {\\em routes} rather than {\\em edges} as primitives. This article is intended to introduce the relevant (discrete setting notion of {\\em routed network} to graph theorists. We give a naive classification of all 71 topologically different such networks on 4 leaves, and pose a variety of challenging research questions.

Augmenting static and dynamic mechanical strength of carbon nanotube/epoxy soft nanocomposites via modulation of purification and functionalization routes.

Science.gov (United States)

Billing, Beant Kaur; Dhar, Purbarun; Singh, Narinder; Agnihotri, Prabhat K

2018-01-03

A detailed experimental investigation was carried out to establish the relationship between CNT purification and functionalization routes and the average response of CNT/epoxy nanocomposites under static and dynamic loading. It was shown that the relative improvement in the mechanical properties of the epoxy matrix due to the addition of CNTs depends on the choice of purification and functionalization steps. A better dispersion of CNTs was recorded for the functionalized CNTs as compared to the oxidized and CVD grown CNTs. Moreover, tensile, 3-point bending and nanoDMA testing performed on nanocomposites processed with CVD-grown, oxidized and functionalized CNTs revealed that COOH functionalization after the oxidation of CNTs at 350 °C is the optimized processing route to harness the excellent properties of CNTs in CNT/epoxy nanocomposites.

[Internal migration studies].

Science.gov (United States)

Stpiczynski, T

1986-10-01

Recent research on internal migration in Poland is reviewed. The basic sources of data, consisting of censuses or surveys, are first described. The author discusses the relationship between migration studies and other sectors of the national economy, and particularly the relationship between migration and income.

The apparent and effective chloride migration coefficients obtained in migration tests

NARCIS (Netherlands)

Spiesz, P.R.; Brouwers, H.J.H.

2013-01-01

The apparent (Dapp) and effective (Deff) migration coefficients obtained in chloride migration tests are investigated in this study. The presented Dapp profiles in concrete show that the apparent migration coefficient is strongly concentration-dependent. As demonstrated, the binding of chlorides is

Road Routes for Waste Disposal - MDC_RecyclingRoute

Data.gov (United States)

NSGIC Local Govt | GIS Inventory — This CURBSIDE RECYCLING ROUTES BOUNDARIES LAYER IS A polygon feature class created for the Miami-Dade Department of Solid Waste Management (DSWM). It contains the...

Porcelain tiles by the dry route

International Nuclear Information System (INIS)

Melchiades, F. G.; Daros, M. T.; Boschi, A. O.

2010-01-01

In Brazil, the second largest tile producer of the world, at present, 70% of the tiles are produced by the dry route. One of the main reasons that lead to this development is the fact that the dry route uses approximately 30% less thermal energy them the traditional wet route. The increasing world concern with the environment and the recognition of the central role played by the water also has pointed towards privileging dry processes. In this context the objective of the present work is to study the feasibility of producing high quality porcelain tiles by the dry route. A brief comparison of the dry and wet route, in standard conditions industrially used today to produce tiles that are not porcelain tiles, shows that there are two major differences: the particle sizes obtained by the wet route are usually considerably finer and the capability of mixing the different minerals, the intimacy of the mixture, is also usually better in the wet route. The present work studied the relative importance of these differences and looked for raw materials and operational conditions that would result in better performance and glazed porcelain tiles of good quality. (Author) 7 refs.

VANET Routing Protocols: Pros and Cons

OpenAIRE

Paul, Bijan; Ibrahim, Md.; Bikas, Md. Abu Naser

2012-01-01