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Abstract The quantitative study of traffic dynamics is crucial to ensure the efficiency of urban transportation networks. The current work investigates the spatial properties of congestion, that is, we aim to characterize the city areas where traffic bottlenecks occur. The analysis of a large amount of real road networks in previous works showed that congestion points experience spatial abrupt transitions, namely they shift away from the city center as larger urban areas are incorporated. The fundamental ingredient behind this effect is the entanglement of central and arterial roads, embedded in separated geographical regions. In this paper we extend the analysis of the conditions yielding abrupt transitions of congestion location. First, we look into the more realistic situation in which arterial and central roads, rather than lying on sharply separated regions, present spatial overlap. It results that this affects the position of bottlenecks and introduces new possible congestion areas. Secondly, we pay particular attention to the role played by the edge distribution, proving that it allows to smooth the transitions profile, and so to control the congestion displacement. Finally, we show that the aforementioned phenomenology may be recovered also as a consequence of a discontinuity in the node’s density, in a domain with uniform connectivity. Our results provide useful insights for the design and optimization of urban road networks, and the management of the daily traffic.

Introduction: Older adults use the emergency department (ED) at high rates, including for illnesses that could be managed by their primary care providers (PCP). Policymakers have implemented barriers and incentives, often financial, to try to modify use patterns but with limited success. This study aims to understand the factors that influence older adults’ decision to obtain acute illness care from the ED rather than from their PCPs. Methods: We performed a qualitative study using a directed content analysis approach from February to October 2013. Fifteen community-dwelling older adults age≥65 years who presented to the ED of an academic medical center hospital for care and who were discharged home were enrolled. Semi-structured interviews were conducted initially in the ED and subsequently in patients’ homes over the following six weeks. All interviews were audio-recorded, transcribed, verified, and coded. The study team jointly analyzed the data and identified themes that emerged from the interviews. Results: The average age of study participants was 74 years (standard deviation ±7.2 years); 53% were female; 80% were white. We found five themes that influenced participants’ decisions to obtain acute illness care from the ED: limited availability of PCP-based care, variable interactions with healthcare providers and systems, limited availability of transportation for illness care, desire to avoid burdening friends and family, and previous experiences with illnesses.  Conclusion: Community-dwelling older adults integrate multiple factors when deciding to obtain care from an ED rather than their PCPs. These factors relate to personal and social considerations, practical issues, and individual perceptions based on previous experiences. If these findings are validated in confirmatory studies, policymakers wishing to modify where older adults receive care should consider person-centered interventions at the system and individual level, such as decision support, telemedicine, improved transport services, enhancing PCPs’ capabilities, and enhancing EDs’ resources to care for older patients.

Streaming students in secondary mathematics classrooms is a common practice in the province of Ontario, although there is conflicting evidence of its benefits. In this province, three streams of mathematics are available in grade 9. One of these streams, termed "locally developed," is based on the idea that school boards and teachers would have some flexibility in the curriculum, based on differing student needs. As such, these courses fall outside the realm of the standardized provincial tests, and hence less is known about these courses, and their students' and teachers' needs. Teachers in one school were interviewed in order to provide a baseline case study, in order to examine their perceived challenges, needs, and views about the courses and the students in them. Recommendations for further study are included.

Chytridiomycosis, a disease caused by the fungus Batrachochytrium dendrobatidis (Bd), has been linked with the disappearance of amphibian populations worldwide. Harlequin toads (Atelopus) are among the most severely impacted genera. Two species are already considered extinct and most of the others are at high risk of extinction. The recent rediscovery of harlequin toad populations coexisting with Bd suggest that the pathogen can maintain enzootic cycles at some locations. The mechanisms promoting coexistence, however, are not well understood. We explore the dynamics of Bd infection in harlequin toads by modeling a two-stage host population with transmission through environmental reservoirs. Simulations showed that variations in the recruitment of adults and the persistence of zoospores in the environment were more likely to drive shifts between extinction and coexistence than changes in the vulnerability of toads to infection with Bd. These findings highlight the need to identify mechanisms for assuring adult recruitment or minimizing transmission from potential reservoirs, biotic or abiotic, in recovering populations.

Testing and isolation have been crucial for controlling the COVID-19 pandemic. Venezuela has one of the weakest testing infrastructures in Latin America and the low number of reported cases in the country has been attributed to substantial underreporting. However, the Venezuelan epidemic seems to have lagged behind other countries in the region, with most cases occurring within the capital region and four border states. Here, we describe the spatial epidemiology of COVID-19 in Venezuela and its relation to the population mobility, migration patterns, non-pharmaceutical interventions and fuel availability that impact population movement. Using a metapopulation model of SARS-CoV-2 transmission dynamics, we explore how movement patterns could have driven the observed distribution of cases. Low within-country connectivity most likely delayed the onset of the epidemic in most states, except for those bordering Colombia and Brazil, where high immigration seeded outbreaks. NPIs slowed early epidemic growth and subsequent fuel shortages appeared to be responsible for limiting the spread of COVID-19 across the country.

Providing high quality light to users in a consistent and reliable manner is one of the main goals of the accelerator physics group at the Advanced Light source (ALS). To meet this goal considerable time is spent monitoring the performance of the machine. At the Group's weekly meeting the performance of the accelerator over the previous week's run is reviewed. This paper describes the parameters that are monitored to optimize the performance of the ALS.

BackgroundFlubendazole, originally developed to treat infections with intestinal nematodes, has been shown to be efficacious in animal models of filarial infections. For treatment of filarial nematodes, systemic exposure is needed. For this purpose, an orally bioavailable amorphous solid dispersion (ASD) formulation of flubendazole was developed. As this formulation results in improved systemic absorption, the pharmacokinetic and toxicological profile of the flubendazole ASD formulation have been assessed to ensure human safety before clinical trials could be initiated.Methods & findingsSafety pharmacology, toxicity and genotoxicity studies have been conducted with the flubendazole ASD formulation. In animals, flubendazole has good oral bioavailability from an ASD formulation ranging from 15% in dogs, 27% in rats to more than 100% in jirds. In in vivo toxicity studies with the ASD formulation, high systemic exposure to flubendazole and its main metabolites was reached. Flubendazole, up to high peak plasma concentrations, does not induce Cmax related effects in CNS or cardiovascular system. In repeated dose toxicity studies in rats and dogs, flubendazole-induced changes were observed in haematological, lymphoid and gastrointestinal systems and in testes. In dogs, the liver was an additional target organ. Upon treatment cessation, at least partial recovery was observed for these changes in dogs. In rats, the No Observed Adverse Effect Level (NOAEL) was 5 mg (as base)/kg body weight/day (mg eq./kg/day) in males and 2.5 mg eq./kg/day in females. In dogs, the NOAEL was lower than 20 mg eq./kg/day. Regarding genotoxicity, flubendazole was negative in the Ames test, but positive in the in vivo micronucleus test.ConclusionsBased on these results, in combination with previously described genotoxicity and reproductive toxicity data and the outcome of the preclinical efficacy studies, it was concluded that no flubendazole treatment regimen can be selected that would provide efficacy in humans at safe exposure.

During the last decades, the study of cities has been transformed by new approaches combining engineering and complexity sciences. Network theory is playing a central role, facilitating the quantitative analysis of crucial urban dynamics, such as mobility, city growth, or urban planning. In this work we focus on the spatial aspects of congestion. Analyzing a large amount of real city networks, we show that the location of the onset of congestion changes according to the considered urban area, defining, in turn, a set of congestion regimes separated by abrupt transitions. To help unveiling this spatial dependencies of congestion (in terms of network betweenness analysis), we introduce a family of planar road network models composed by a dense urban center connected to an arboreal periphery. These models, coined as GT and DT-MST models, allow us to analytically, numerically, and experimentally describe how and why congestion emerges in particular geographical areas of monocentric cities and, subsequently, to describe the congestion regimes and the factors that promote the appearance of their abrupt transitions. We show that the fundamental ingredient behind the observed abrupt transitions is the spatial separation between the urban center and the periphery, and the number of separated areas that form the periphery. Elaborating on the implications of our results, we show that they may have influence in the design and optimization of road networks regarding urban growth and the management of daily traffic dynamics.

Harlequin Toads (Bufonidae: Atelopus) are among the most diverse Neotropical amphibians, but 84% of the known species are threatened with extinction mainly due to the fungal disease chytridiomycosis. With no effective tools to mitigate chytridiomycosis in the wild being available, captive breeding is currently the only option to ensure the long-term survival of many Harlequin Toad species. However, the life history and ecology of most species is still largely unknown. Using spatially explicit capture-recapture data from 2005-2013, we studied breeding habitat use and reproductive phenology of the critically endangered Rancho Grande Harlequin Toad, Atelopus cruciger. This species is a seasonal breeder that reproduces exclusively during the dry season. Adult males and females, but also juveniles, migrate from the forest to the river at the beginning of the dry season and return to the forest as soon as the rainy season begins, although a few adult males may remain on the riverbank throughout the year. Despite these seasonal displacements, the toads return to the same locations on the riverbank every year. Both female and male adult toads exhibit a strong breeding site fidelity, occupying small areas (= 5 m2) along the river margins. Adults were mainly active on rocky substrate and vegetation during the day, with males occupying significantly more elevated spots closer to the stream than females. Male territories tend to overlap, but we observed no aggressive or territorial defence behaviour. We discuss the implications of habitat use and high site fidelity for in situ and ex situ conservation measures of this critically endangered toad. [ABSTRACT FROM AUTHOR]

Long-term demographic data are valuable for assessing the effect of anthropogenic impacts on endangered species and evaluating recovery programs. Using a 2-state open robust design model, we analyzed mark-recapture data from green turtles Chelonia mydas sighted between 1979 and 2009 on Aves Island, Venezuela, a rookery heavily impacted by human activities before it was declared a wildlife refuge in 1972. Based on the encounter histories of 7689 nesting females, we estimated the abundance, annual survival, and remigration intervals for this population. Female survival varied from 0.14-0.91, with a mean of 0.79, which is low compared to survival of other populations from the Caribbean (mean = 0.84) and Australia (mean = 0.95), even though we partially corrected for tag loss, which is known to negatively bias survival estimates. This supports prior suggestions that Caribbean populations in general, and the Aves Island population in particular, may be more strongly impacted than populations elsewhere. It is likely that nesters from this rookery are extracted while foraging in remote feeding grounds where hunting still occurs. Despite its relatively low survival, the nesting population at Aves Island increased during the past 30 years from approx. 500 to >1000 nesting females in 2009. Thus, this population, like others in the Caribbean and the Atlantic, seems to be slowly recovering following protective management. Although these findings support the importance of long-term conservation programs aimed at protecting nesting grounds, they also highlight the need to extend management actions to foraging grounds where human activities may still impact green turtle populations.