Departure Dates Research Articles

Epidemiology and Clinical Outcomes of COVID-19 Patients in Northwestern China Who Had a History of Exposure in Wuhan City: Departure Time-Originated Pinpoint Surveillance.

Background: Most COVID-19 patients cannot provide a clear exposure time; therefore, this study was designed to predict the progression of COVID-19 by using the definite departure time from Wuhan.Methods: In this retrospective study, all cases were selected from Northwestern China, which has the lowest population density. As our study endpoints, the incubation period was defined as the date of departure from Wuhan City to the date of symptom onset; we defined the confirmed time as the interval from symptom onset to positive results (samples from the respiratory tract). Both of them were estimated by fitting a Weibull distribution on the departure date and symptom onset. The differences among the variables were analyzed.Results: A total of 139 patients were ultimately enrolled, and ~10.1% of patients (14 patients) had no symptoms during their disease course. We estimated the median incubation period to be 4.0 days (interquartile intervals, 2.0–8.0), and the 95th percentile of the distribution was 15.0 days. Moreover, ~5.6% of patients (7 patients) experienced symptoms 2 weeks after leaving. Furthermore, the estimation median interval from symptom onset to final diagnosis was 4.0 days (interquartile intervals, 2.0–6.0), and the 95th percentile of the distribution was 12.0 days. Finally, the median hospitalization time was 16.0 days, ranging from 3.0 to 45.0 days. Univariate analysis showed that age (P = 0.021) and severity status (P = 0.001) were correlated significantly with hospitalization time.Conclusions: We provide evidence that departure time can be used to estimate the incubation and confirmed times of patients infected with COVID-19 when they leave an epidemic area.

해방 이후 상해를 통해 한국으로 돌아온 한인

After the Liberation, the population of East Asia was newly formed. At this time, the People's Party of China's government implemented a policy called “collective return to concentration,” and designated Shanghai Port as the main channel for the return of Koreans. The return of Koreans to Shanghai is largely divided into “return preparation stage,” “group return stage,” and “individual return stage,” depending on the size and policy. In the return preparation stage, 29 key figures from the Provisional Government of the Republic of Korea will return. During the group return stage, 1,500 to 5,000 people will move to Korea about 10 times. Afterwards, the number of employees will be reduced to 100 to 500 during the individual return stage. In connection with the news of the return of Koreans from Shanghai to Korea, the Korean media informed Korea of various facts, including the route, ship name, departure date and arrival date, number of people aboard and key figures. It also issues the poor lives of Koreans in Shanghai and the difficulties they face after returning to Korea. It also reports in detail on the outbreak of cholera, an infectious disease spread to Korea as the population moves. Such an article by the Korean media is the basis for a clearer picture of the entire return of Koreans in Shanghai, which is difficult to reveal with only the currently excavated feed.

Insights into migratory connectivity and conservation concerns of Red Knots Calidris canutus in the austral Pacific coast of the Americas

SummaryMigratory species rely on several distant sites during the annual cycle which makes their conservation more complex than that of non-migratory species. Even one of the most extensively studied migratory shorebirds - the Red Knot Calidris canutus - is currently ‘Near Threatened’ at the global level. Conflicting observations of migratory routes cast uncertainty on the subspecies classification and migratory connectivity of Red Knots in the Pacific coasts of the Americas. To fill essential information gaps, we present the first detailed population morphometrics of Red Knots during the non-breeding season in the southern Pacific coast, along with resightings of these birds throughout the Americas. We also estimated daily rate of weight gain during fuelling based on body mass at captures and known departure dates. Resightings demonstrate reliance on staging areas in both the Mid-continental and Atlantic flyways during the northward migration, and additionally in the Pacific Flyway during southward migration. In addition to the strong connection with several areas also used by C. c. rufa on the North American Atlantic coast, our results show morphometric differences within the ranges of both C. c. rufa and C. c. roselaari. Given the threats faced by Red Knots, the population in Chiloé Archipelago should be treated as a separate conservation unit within interhemispheric conservation programmes for endangered shorebirds within the Americas.

New Data on Migration Time, Breeding Phenology, and Breeding Success of European Turtle Doves in Their Highest Breeding Habitats in North Africa

The migration dates, breeding phenology, and reproductive success of the European turtle doves were studied in the highest breeding habitats at Midelt (1400 to 1600 m), Morocco. Data were recorded from March to October between 2015 and 2018, using the Common Bird Census methodology. Results showed that, at high-altitude breeding sites (n = 20), turtle doves arrived on 28.25 ± 2.05 March, while departure dates were on 28.00 ± 1.47 September. On the other hand, nesting activity began on 26.5 ± 0.64 April, and laying dates were only two days after the nest construction date on 28.00 ± 0.7 April. First fledged chicks were 17.50 ± 2.72 May, and chicks started flying on 3.50 ± 2.33 June. In addition, breeding chronology, including nesting and chick’s flight, was influenced by altitude and rainfall and more particularly controlled by temperature. For breeding success, among the 467 monitored nests, 73.87% survived during the nesting period and 71.16% of eggs have survived during incubation. Chicks' survival rate was higher with 79.56%. Failure factors during breeding success were diverse. Predation caused the loss of 18.89% of eggs during incubation periods and 10.54% of chicks during the nestling phase. A few portions, including 4.41% of eggs and 4.39% of chicks, were deserted by their dove parents. Finally, our study highlights that the turtle dove breeds in high-altitude habitats with late and shorter breeding periods, which might allow this bird to avoid the vigorous climate conditions at mountains and their effect on reproductive success.

Multiple environmental factors and prey depletion determine declines in abundance and timing of departure in migratory shorebirds in the west coast of India

Shorebirds around the world have been undergoing significant declines as well as alterations in patterns of migratory phenology due to major changes in the environment. Many of these changes have been linked with anthropogenic factors such as urbanization, environmental degradation, habitat loss and global climate change. We studied the abundance of 15 migratory shorebird species in a coastal wetland in western India that serves as an important stopover and wintering area by many shorebirds in the Central Asian Flyway. The study site was visited once a week during low tide (from 06:00–12:00 h) for 15 years (2005–2019). Shorebird abundance data was collected following direct count and block count methods. To study the departure of shorebirds we monitored shorebird numbers daily and collected benthic organisms three times a month from the shoreline habitats during low tide. Samples were collected from depths of 15 cm using a metal cylinder from areas that typically had the highest densities of foraging shorebirds. Daily rainfall, relative humidity, temperature of air and water and salinity were measured once a week. Generalized Linear Models GLMs (Gaussian family) was used to determine the variation in shorebird abundance in relation to environmental variables (relative humidity, water salinity, rainfall, water temperature, air temperature), and invertebrate prey abundance. We ran two GLMs with Poisson distribution of error to investigate if departure date varied with environmental variables and the abundance of invertebrate prey. Of the environmental variables, mean air temperature, water temperature and salinity increased significantly during the 15 years while invertebrate prey underwent steep declines. Ten of the 15 species’ declines were predicted by the changes in relative humidity, rainfall, water temperature, air temperature, salinity and invertebrate prey abundance. Departure dates also advanced in several species and were affected by relative humidity, air temperature, water temperature, salinity and invertebrate prey abundance. Our models suggest that salinity and invertebrate prey abundance were driving overall changes in shorebird abundance and departure dates. These two variables were negatively related (invertebrate prey abundance declined with increasing salinity). This was evident throughout the study period, during which salinity increased while invertebrate prey abundance declined. Species declines could be due to poor habitat quality and food availability resulting from environmental degradation. Delays in migration could be linked with inability to find enough high quality food to build up food reserves prior to departure. Better habitat management in key wintering wetlands and stopover sites along the flyway are needed help to restore populations of shorebirds.

Avian migrants encounter higher temperatures but continue to add mass at an inland stopover site in the Great Lakes region

As the climate changes, mismatches in phenology between predator and prey species may become more common. For example, many songbirds rely on short peaks in insect and fruit production at stopover sites during migration. Previous research indicates that migratory songbirds are able to modify their departure and arrival dates to some extent despite their reliance on more stable cues such as photoperiod and more stable endogenous factors. However, insect and plant phenology may shift more rapidly with changing climate, reducing foraging opportunities along migratory routes. To quantify changes in songbird arrival patterns at stopover sites during fall migration we analyzed forty years of banding data in nine passerine species commonly captured at banding stations in southwestern Michigan. Weather data revealed that the region has warmed by nearly 2° (C) over this timeframe. For each species, we assessed annual trends in arrival date and temperature at arrival. To determine whether arrival trends impacted stopover site function we also quantified trends in site use and morning mass gain. Arrival dates advanced significantly in three species, and were delayed significantly in three other species. However, air temperature at arrival increased significantly over time for all nine study species. Over the same time period, site use and the pattern of morning mass gain remained stable or increased for all species. Despite the changing climate and the resulting increase in temperature at arrival for migrants, our data indicate that these stopover locations continue to function as a refueling sites. Nonetheless, we must be wary of thresholds and ecological mismatches that may occur if warming trends continue.

Solving an integrated scheduling and routing problem with inventory, routing and penalty costs

This paper considers an integrated routing and scheduling problem where the routing part takes into account routing costs and tardiness penalties and the scheduling part is modelled by a permutation flow shop with inventory costs. We assume that each batch is served by a dedicated vehicle, and that the number of batches and their compositions (the number of jobs and the parameters of those jobs) are known in advance. The problem is to determine the starting times of the jobs on each machine in the flow shop, the departure dates of the batches and their delivery route, such that the total cost (sum of inventory, routing and penalty costs) is minimised. A two-step approach is proposed. In a first step, the optimal delivery routes for each batch and each possible departure date are calculated. This is possible as determining the min cost route for a particular delivery batch and a particular departure date is easy. In a second step, we use the delivery cost function for each batch, depending on the departure date, from the first step, to find a schedule that minimises the total cost. Computational experiments are performed on randomly generated instances.

A production and distribution framework: Manufacturer dominates

This paper presents a two-stage supply chain problem at the operational level involving a manufacturer and a third-party logistics provider (3PL provider). The integrated problem consists of two subproblems: An m-machine permutation flow shop with inventory considerations for the manufacturer and a routing problem for the 3PL provider. Both agents face tardiness penalty costs in case of late delivery to the customer locations. Assuming imperfect information sharing between the two agents and independence in their own decisions, we investigate the scenario in which the manufacturer dominates the negotiation.In this scenario, the manufacturer imposes the number and composition of vehicles as well as the vehicle departure dates on the 3PL provider. However, lacking the information regarding the actual delivery times he is forced to estimate delivery times at the customer locations in the context of his planning. Following the planning of the manufacturer, the 3PL provider decides on the optimal routing of the vehicles. Both agents aim to minimise their total costs. After formulating the problems as a mixed integer linear program, two metaheuristic algorithms are proposed to solve the scenario. The performance of the heuristics is evaluated on a set of randomly generated instances. The results show that the genetic algorithm is the best performing method.

Interspecific competition between resident and wintering birds: experimental evidence and consequences of coexistence.

The contribution of interspecific competition to structuring population and community dynamics remains controversial and poorly tested. Interspecific competition has long been thought to influence the structure of migrant-resident bird communities in winter, yet experimental evidence remains elusive. The arrival of billions of songbirds into Neotropical habitats, where they co-exist with residents, provides a unique opportunity to assess interspecific competition and its consequences. Working in 15ha of Jamaican black mangrove forest, we used removal experiments to test whether dominant resident Yellow Warblers compete interspecifically with subordinate wintering American Redstarts; we also used observational evidence (interspecific territorial overlap) to understand whether this coexistence influences physical condition, spring departure dates or annual return rates. Consistent with interspecific competition, after experimental removal of the resident, yearling male Redstarts (but not females or adult males) immediately moved into vacated Yellow Warbler territories, increasing their overlap with the space by 7.3%. Yearling Redstarts also appeared to adjust their territorial space use by actively avoiding Yellow Warblers; for example, Redstarts departing the wintering grounds as yearlings and returning the following winter shifted such that their territories overlapped 32% less with those of Yellow Warblers. Adult Redstarts showed no such territorial flexibility. Adult male Redstarts also showed evidence supporting the consequences of coexistence: territorial overlap with Yellow Warblers was negatively correlated with body condition and annual return rates. Adult male Redstarts with <25% territorial overlap with Yellow Warblers were more than three times as likely to return between seasons than those with 100% overlap. We propose that the territorial inflexibility of adult male Redstarts produces these consequences, which may be due to their years-long investment in that particular territory. More generally, the temporary nature of migrant-resident interspecific competition is likely what allows coexistence during winter, the most resource-poor time of year. Interspecific competition and the consequences of coexistence are likely age- and sex-specific and the product of intraspecific dominance hierarchy in Redstarts. Our observations suggest that interspecific coexistence has measurable consequences, and our experiments support the long-held, but previously untested belief that resident birds compete interspecifically with wintering migrants.

Post-COVID-19 behavior change in purchase of air tickets

• We analyze the intentions to buy air tickets in advance once back to normal. • 28% of air travelers will buy their tickets closer to their departure date. • 5% will not fly in the next years, even if they have in the past few years. • 4% will buy earlier, mainly due to economic reasons.

Application of machine learning techniques in railway demand forecasting

Demand forecasting lies at the heart of any revenue management system. It aims to estimate the quantity of a product or service that will be purchased in the future. In this paper, we perform railway demand forecasting for a major European railroad company by taking various contributing parameters into account. To have multipurpose results, the current problem is explored in two different aggregation levels. At the high level, the problem is defined as prediction of the total number of bookings for all trains departing on a specific departure date and within a certain time range. Moreover, in a more disaggregated level, the prediction models aim to compute the total number of bookings within each booking period for all trains leaving in a specific time range of a certain departure date. Using state-of-the-art machine learning methods and various heuristic feature construction techniques, remarkable results with high forecast accuracy and reasonable computational complexity are achieved in both aggregation levels. This paper aims to contribute to the application of ML techniques in RM by introducing new heuristic feature engineering techniques, exploring the importance of accurate clustering, and implementing state-of-the-art machine learning methods in the context of railway industry.

Application of Machine Learning Techniques in Railway Demand Forecasting

Demand forecasting lies at the heart of any revenue management system. It aims to estimate the quantity of a product or service that will be purchased in the future. In this paper, we perform railway demand forecasting for a major European railroad company by taking various contributing parameters into account. To have multipurpose results, the current problem is explored in two different aggregation levels. At the high level, the problem is defined as prediction of the total number of bookings for all trains departing on a specific departure date and within a certain time range. Moreover, in a more disaggregated level, the prediction models aim to compute the total number of bookings within each booking period for all trains leaving in a specific time range of a certain departure date. Using state-of-the-art machine learning methods and various heuristic feature construction techniques, remarkable results with high forecast accuracy and reasonable computational complexity are achieved in both aggregation levels. This paper aims to contribute to the application of ML techniques in RM by introducing new heuristic feature engineering techniques, exploring the importance of accurate clustering, and implementing state-of-the-art machine learning methods in the context of railway industry.

Foraging efforts and behaviour of the European Turtle doves (Streptopelia turtur) during the breeding season

During the breeding season, many avian species face spatial and seasonal variation in the availability of food resources required to rear chicks. Reduction of food abundance is often identified as the most important factor determining population trends and breeding success in bird species, such as the vulnerable European Turtle dove Streptopelia turtur. During the breeding periods, the increase of food requirements in chicks should increase foraging effort to maintain the amount of food required for optimal chick development. To investigate the feeding effort of Turtle doves during the breeding season, we monitored foraging and drinking rates, in different wild habitats and farmlands, from March to September 2016-2017 in Midelt, Morocco. Similarly, breeding chronology, including nesting, laying, and chicks' fledging, were monitored in the same habitats to evaluate the correlation between breeding efforts and foraging rates. We found that Turtle doves feed actively from the arrival to departure dates. Foraging activities were intense during breeding phases, mainly laying and chicks' growth periods. Equally, Doves feed intensively during the end of the breeding season before migration departures. Besides, Doves feed actively during the morning and evening to avoid the hottest periods as a strategy to save metabolic water.

Considering EU External Relations after Brexit: Introduction

This special issue of Europe and the World: A law review consists of selected articles that were presented at a workshop on External Relations in the post-Brexit EU, University of Strathclyde, Glasgow in October 2018. The workshop was generously funded by the James Madison Charitable Trust and the New Professors Fund of the University of Strathclyde. The purpose of the workshop was to consider the multifaceted dimensions of Brexit on the European Union’s external relations, and in particular to consider how interdisciplinary perspectives can enrich our understanding of the law underpinning the subject. This includes the EU’s externally facing institutional frameworks; law and policy on foreign, security and defence policies; trade and the Common Commercial Policy; and bilateral agreements with third countries or regions. The workshop was held around the mid-point in time from the referendum of June 2016 until the eventual departure of the UK on 31 January 2020 (although the final departure date and exit arrangements were unknown at the time). As such, the workshop contributors based their analyses on what the future impact of Brexit might be. Drawing on the extensive scholarship on EU external relations that has blossomed over previous decades, the authors of this special issue have been able to comprehensively analyse what future EU external relations might look like.

Snapshot Models of Undocumented Immigration

Accurately estimating the size of the undocumented immigrant population is a critical component of assessing the health and security risks of undocumented immigration to the United States. To provide one such estimate, we use data from the Mexican Migration Project (MMP), a study that includes samples of undocumented Mexican immigrants to the United States after their return to Mexico. Of particular interest are the departure and return dates of a sampled migrant's most recent sojourn in the United States, and the total number of such journeys undertaken by that migrant household, for these data enable the construction of data-driven undocumented immigration models. However, such data are subject to an extreme physical bias, for to be included in such a sample, a migrant must have returned to Mexico by the time of the survey, excluding those undocumented immigrants still in the United States. In our analysis, we account for this bias by jointly modeling trip timing and duration to produce the likelihood of observing the data in such a "snapshot" sample. Our analysis characterizes undocumented migration flows including single-visit migrants, repeat visitors, and "retirement" from circular migration. Starting with 1987, we apply our models to 30 annual random snapshot surveys of returned undocumented Mexican migrants accounting for undocumented Mexican migration from 1980 to 2016. Scaling to population quantities and supplementing our analysis of southern border crossings with estimates of visa overstays, we produce lower bounds on the total number of undocumented immigrants that are much larger than conventional estimates based on U.S.-based census-linked surveys, and broadly consistent with the more recent estimates reported by Fazel-Zarandi, Feinstein, and Kaplan.

Increased Stopover Duration and Low Body Condition of the Pied Flycatcher (Ficedula hypoleuca) at an Autumn Stopover Site.

Simple SummaryMany bird species that migrate long distances are in decline partly because of environmental changes, such as climate change or land-use changes. Although much is already known on the effects of environmental change on birds that are on their spring migration or on their breeding grounds, little is known with regard to possible negative effects on birds that are on their autumn migration and visiting so-called stopover sites on their way to their wintering grounds. These stopover sites are vital for birds to refuel, and a potential deteriorating quality of the stopover sites may lead to individuals dying during migration. We investigated the impacts of local environmental conditions on the migration strategy and body condition of the Pied Flycatcher at an autumn migration stopover site using long-term ringing data and local environmental conditions. We found that although birds arrived and departed the stopover site around the same time over the years, the body condition of the individuals caught decreased, and the length of their stay at the stopover site increased. This suggests that conditions at the stopover site during the autumn migration period have deteriorated over time which may lead to the death of more birds during autumn migration.Many long-distance migratory bird species are in decline, of which environmental changes, such as climate change and land-use changes, are thought to be important drivers. The effects of environmental change on the migration of these birds have often been studied during spring migration. Fewer studies have explored the impacts of environmental change on autumn migration, especially at stopover sites. However, stopover sites are important, as the quality of these sites is expected to change over time. We investigated impacts of local environmental conditions on the migration strategy and body condition of the Pied Flycatcher (Ficedula hypoleuca) at an autumn migration stopover site using long-term ringing data (1996–2018) and local environmental conditions. We found that although the arrival and departure dates of birds at the stopover site remained unchanged, the body condition (fat score) of the individuals caught decreased, and the stopover duration increased. This suggests that conditions at the stopover site during the autumn migration period have deteriorated over time. This study emphasizes the importance of suitable stopover sites for migratory birds and stresses that changes in environmental conditions during the autumn migration period may be contributing to the current decline in long-distance migratory passerines.

Migratory Dates, Breeding Phenology, and Reproductive Success of European Turtle Doves between Lowlands and Highest Breeding Habitats in North Africa

The migratory time, breeding chronology, and reproductive success of the European turtle doves (Streptopelia turtur) were studied in Midelt as a high-altitude breeding habitat and Beni Mellal as a low-altitude breeding site from 2015 to 2018 in Morocco. Migration dates, breeding phenology, and breeding success were recorded from March to October for each season. As a result, during four years, arrival dates were earlier at the low breeding site, while departure dates were earlier at the high breeding site. Similarly, breeding phenology from nest building to fledging was early at low-altitude site. On the other hand, with four breeding seasons and 893 nests (467 at Midelt and 426 at Beni Mellal), average breeding success was 57% of chicks at Midelt compared to 60.15% at Beni Mellal. Moreover, at Midelt, 18.89% of eggs and 10.54% of chicks were predated, while at Beni Mellal 21.80% of eggs and 4.65% of chicks were deserted due to human disturbance. As a response, at Midelt breeding period was shorter and shifted to hot periods to ensure better reproductive success. Finally, our results highlight that the turtle dove breeding season is later and shorter at breeding highlands, which might allow this bird to avoid the vigorous climate conditions at mountains and their effect on reproductive success.

Population‐specific adjustment of the annual cycle in a super‐swift trans‐Saharan migrant

For migratory birds optimal timing of the onset of reproduction is vital, especially when suitable conditions for reproduction occur only for a short while during the year. With increasing latitude the suitable period becomes shorter and we expect the organization of annual cycle to be more synchronized to the local conditions across individuals of same population. This should result in low variation of arrival and departure date in breeding sites at higher latitudes. We quantify the temporal and geographical variation in pre‐ and post‐breeding migration between individuals from four different populations of alpine swifts Tachymarptis melba along a latitudinal gradient. We tracked 215 individuals in three years with geolocators. The two western and two eastern populations showed separate migratory flyways and places of residence in Africa. Length of stay at the breeding sites was negatively correlated with latitude and differed by more than a month between populations. Duration of migration was similarly short in all populations (median 6.2 days in autumn and 8.7 days in spring). However, variation in timing of migration was unrelated to latitude and individuals everywhere arrived in the same asynchrony at the breeding site.

Earlier and slower or later and faster: Spring migration pace linked to departure time in a Neotropical migrant songbird.

Migratory birds travel vast distances and the timing of migratory flights can affect survival and the ability to reproduce. For Neotropical migrant songbirds, early spring departure from wintering sites, early arrival to the breeding grounds and higher reproductive success have been related to the use of suitable habitats and environmental conditions during the non-breeding season. However, how migratory strategies are shaped by winter habitat choice is largely unknown due to the general inability to track birds from specific wintering habitats to stopovers or breeding destinations. We assessed how winter habitat (native forest vs. shade-grown coffee plantations) relates to spring departure date and migration pace in Swainson's Thrush Catharus ustulatus. We also determined the effect of departure date and total migration duration on the arrival date of birds detected near or within their breeding range. We used a novel application of Motus radiotelemetry arrays to track individuals from their wintering grounds in the Andes of South America along their migratory journey to North America. We found variation in migratory strategies between habitats, with birds wintering in native forest departing later than birds in coffee. We present isotopic evidence for native forest being of higher quality than shade-coffee for Swainson's Thrush and hypothesize that moister conditions in forest, as shown by stable isotope (δ13 C) analysis of thrush whole blood, provides favourable pre-migratory conditions allowing birds to delay departure from wintering grounds. Habitat, between-site and -year variation in departure date, suggests that birds made facultative adjustments to winter habitat quality and environmental conditions. Independent of habitat, birds that departed later migrated faster and this pattern was maintained along the migration route (n=44). Migrating earlier and slower or later and faster was unlikely to result in significant differences in arrival time to breeding destinations. Our findings reveal underappreciated complexity in migratory decisions by long-distance migrants that contrast with the current paradigm of earlier departures and arrival from optimal habitats. The next step is to understand the relative fitness benefits of early versus late schedules or whether each strategy is an equally good response to experienced conditions.

Chasing the sun: When to migrate, when to breed

Chasing the sun: When to migrate, when to breed