scholarly journals Modelling cholera epidemics: the role of waterways, human mobility and sanitation

2011 ◽  
Vol 9 (67) ◽  
pp. 376-388 ◽  
Author(s):  
L. Mari ◽  
E. Bertuzzo ◽  
L. Righetto ◽  
R. Casagrandi ◽  
M. Gatto ◽  
...  
Keyword(s):  
Long Range ◽  
Large Scale ◽  
Human Mobility ◽  
Human Movement ◽  
Epidemiological Data ◽  
Long Distance ◽  
Regional Patterns ◽  
Spatially Explicit Model ◽  
Kwazulu Natal

We investigate the role of human mobility as a driver for long-range spreading of cholera infections, which primarily propagate through hydrologically controlled ecological corridors. Our aim is to build a spatially explicit model of a disease epidemic, which is relevant to both social and scientific issues. We present a two-layer network model that accounts for the interplay between epidemiological dynamics, hydrological transport and long-distance dissemination of the pathogen Vibrio cholerae owing to host movement, described here by means of a gravity-model approach. We test our model against epidemiological data recorded during the extensive cholera outbreak occurred in the KwaZulu-Natal province of South Africa during 2000–2001. We show that long-range human movement is fundamental in quantifying otherwise unexplained inter-catchment transport of V. cholerae , thus playing a key role in the formation of regional patterns of cholera epidemics. We also show quantitatively how heterogeneously distributed drinking water supplies and sanitation conditions may affect large-scale cholera transmission, and analyse the effects of different sanitation policies.

Role of LHCII-containing macrodomains in the structure, function and dynamics of grana

2000 ◽  
Vol 27 (3) ◽  
pp. 279 ◽  
Author(s):  
G. Garab ◽  
L. Mustárdy
Keyword(s):  
Excitation Energy ◽  
Long Range ◽  
Structural Changes ◽  
Higher Plants ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Lateral Heterogeneity ◽  
Long Distance ◽  
3D Network

In higher plants and green algae two types of thylakoids are distinguished, granum (stacked) and stroma (unstacked) thylakoids. They form a three-dimensional (3D) network with large lateral heterogeneity: photosystem II (PSII) and the associated main chlorophyll a/b light-harvesting complex (LHCII) are found predominantly in the stacked region, while PSI and LHCI are located mainly in the unstacked region of the membrane. This picture emerged from the discovery of the physical separation of the two photosystems (Boardman and Anderson 1964). Granal chloroplasts possess significant flexibility, which is essential for optimizing the photosynthetic machinery under various environmental conditions. However, our understanding concerning the assembly, structural dynamics and regulatory functions of grana is far from being complete. In this paper we overview the significance of the three-dimensional structure of grana in the absorption properties, ionic equilibrations, and in the diffusion of membrane components between the stacked and unstacked regions. Further, we discuss the role of chiral macrodomains in the grana. Lateral heterogeneity of thylakoid membranes is proposed to be a consequence of the formation of macrodomains constituted of LHCII and PSII; their long range order permits long distance migration of excitation energy, which explains the energetic connectivity of PSII particles. The ability of macrodomains to undergo light-induced reversible structural changes lends structural flexibility to the granum. In purified LHCII, which has also been shown to form stacked lamellar aggregates with long range chiral order, excitation energy migrates for large distances; these macroaggregates are also capable of undergoing light-induced reversible structural changes and fluorescence quenching. Hence, some basic properties of grana appear to originate from its main constituent, the LHCII.

scholarly journals A picture of medically assisted reproduction activities during the COVID-19 pandemic in Europe

2020 ◽  
Vol 2020 (3) ◽  
Author(s):  
Nathalie Vermeulen ◽  
◽  
Eduard Hambartsoumian ◽  
Kazem Nouri ◽  
Thomas Ebner ◽  
...  
Keyword(s):  
Assisted Reproduction ◽  
Large Scale ◽  
Health Resources ◽  
Epidemiological Data ◽  
Medically Assisted Reproduction ◽  
Large Scale Data ◽  
Health Authorities ◽  
Current Article ◽  
Competing Interest

Abstract STUDY QUESTION How did coronavirus disease 2019 (COVID-19) impact on medically assisted reproduction (MAR) services in Europe during the COVID-19 pandemic (March to May 2020)? SUMMARY ANSWER MAR services, and hence treatments for infertile couples, were stopped in most European countries for a mean of 7 weeks. WHAT IS KNOWN ALREADY With the outbreak of COVID-19 in Europe, non-urgent medical care was reduced by local authorities to preserve health resources and maintain social distancing. Furthermore, ESHRE and other societies recommended to postpone ART pregnancies as of 14 March 2020. STUDY DESIGN, SIZE, DURATION A structured questionnaire was distributed in April among the ESHRE Committee of National Representatives, followed by further information collection through email. PARTICIPANTS/MATERIALS, SETTING, METHODS The information was collected through the questionnaire and afterwards summarised and aligned with data from the European Centre for Disease Control on the number of COVID-19 cases per country. MAIN RESULTS AND THE ROLE OF CHANCE By aligning the data for each country with respective epidemiological data, we show a large variation in the time and the phase in the epidemic in the curve when MAR/ART treatments were suspended and restarted. Similarly, the duration of interruption varied. Fertility preservation treatments and patient supportive care for patients remained available during the pandemic. LARGE SCALE DATA N/A LIMITATIONS, REASONS FOR CAUTION Data collection was prone to misinterpretation of the questions and replies, and required further follow-up to check the accuracy. Some representatives reported that they, themselves, were not always aware of the situation throughout the country or reported difficulties with providing single generalised replies, for instance when there were regional differences within their country. WIDER IMPLICATIONS OF THE FINDINGS The current article provides a basis for further research of the different strategies developed in response to the COVID-19 crisis. Such conclusions will be invaluable for health authorities and healthcare professionals with respect to future similar situations. STUDY FUNDING/COMPETING INTEREST(S) There was no funding for the study, apart from technical support from ESHRE. The authors had no COI to disclose.

Role of LHCII-containing macrodomains in the structure, function and dynamics of grana

2000 ◽  
Vol 27 (7) ◽  
pp. 723 ◽  
Author(s):  
G. Garab ◽  
L. Mustárdy
Keyword(s):  
Excitation Energy ◽  
Long Range ◽  
Structural Changes ◽  
Higher Plants ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Lateral Heterogeneity ◽  
Long Distance ◽  
3D Network

In higher plants and green algae two types of thylakoids are distinguished, granum (stacked) and stroma (unstacked) thylakoids. They form a three-dimensional (3D) network with large lateral heterogeneity: photosystem II (PSII) and the associated main chlorophyll a/b light-harvesting complex (LHCII) are found predominantly in the stacked region, while PSI and LHCI are located mainly in the unstacked region of the membrane. This picture emerged from the discovery of the physical separation of the two photosystems (Boardman and Anderson 1964). Granal chloroplasts possess significant flexibility, which is essential for optimizing the photosynthetic machinery under various environmental conditions. However, our understanding concerning the assembly, structural dynamics and regulatory functions of grana is far from being complete. In this paper we overview the significance of the three-dimensional structure of grana in the absorption properties, ionic equilibrations, and in the diffusion of membrane components between the stacked and unstacked regions. Further, we discuss the role of chiral macrodomains in the grana. Lateral heterogeneity of thylakoid membranes is proposed to be a consequence of the formation of macrodomains constituted of LHCII and PSII; their long range order permits long distance migration of excitation energy, which explains the energetic connectivity of PSII particles. The ability of macrodomains to undergo light-induced reversible structural changes lends structural flexibility to the granum. In purified LHCII, which has also been shown to form stacked lamellar aggregates with long range chiral order, excitation energy migrates for large distances; these macroaggregates are also capable of undergoing light-induced reversible structural changes and fluorescence quenching. Hence, some basic properties of grana appear to originate from its main constituent, the LHCII.

scholarly journals Exploring the Roles of Local Mobility Patterns, Socioeconomic Conditions, and Lockdown Policies in Shaping the Patterns of COVID-19 Spread

2021 ◽  
Vol 13 (5) ◽  
pp. 112
Author(s):  
Mauricio Herrera ◽  
Alex Godoy-Faúndez
Keyword(s):  
Latin American ◽  
Low Income ◽  
Large Scale ◽  
Human Mobility ◽  
Epidemiological Data ◽  
High Income ◽  
Metropolitan Region ◽  
Mobility Patterns ◽  
Large Cities

The COVID-19 crisis has shown that we can only prevent the risk of mass contagion through timely, large-scale, coordinated, and decisive actions. This pandemic has also highlighted the critical importance of generating rigorous evidence for decision-making, and actionable insights from data, considering further the intricate web of causes and drivers behind observed patterns of contagion diffusion. Using mobility, socioeconomic, and epidemiological data recorded throughout the pandemic development in the Santiago Metropolitan Region, we seek to understand the observed patterns of contagion. We characterize human mobility patterns during the pandemic through different mobility indices and correlate such patterns with the observed contagion diffusion, providing data-driven models for insights, analysis, and inferences. Through these models, we examine some effects of the late application of mobility restrictions in high-income urban regions that were affected by high contagion rates at the beginning of the pandemic. Using augmented synthesis control methods, we study the consequences of the early lifting of mobility restrictions in low-income sectors connected by public transport to high-risk and high-income communes. The Santiago Metropolitan Region is one of the largest Latin American metropolises with features that are common to large cities. Therefore, it can be used as a relevant case study to unravel complex patterns of the spread of COVID-19.

scholarly journals Emergence of Urban Growth Patterns from Human Movements

2020 ◽  
Author(s):  
Fengli Xu ◽  
Yong Li ◽  
Chaoming Song
Keyword(s):  
Urban Growth ◽  
Large Scale ◽  
Scaling Laws ◽  
Human Mobility ◽  
Human Movement ◽  
Urban Morphology ◽  
Growth Patterns ◽  
Spatial Correlations ◽  
Movement Model ◽  
Human Movements

Abstract Cities grow in a bottom-up manner, leading to fractal-like urban morphology characterized by scaling laws. Correlated percolation has succeeded in modeling urban geometries by imposing strong spatial correlations. However, the origin of such correlations remains largely unknown. Very recently, our understanding of human movements has been revolutionized thanks to the increasing availability of large-scale human mobility data. This paper proposes a novel human movement model that offers a micro-foundation for the dynamics of urban growth. We compare the proposed model with three empirical datasets, which evidences that strong social couplings and long-memory effects are two fundamental principles responsible for the mystical spatial correlations. The model accounts for the empirically observed scaling laws, but also allows us to understand the city evolution dynamically.

scholarly journals Megacities as drivers of national outbreaks: the role of holiday travel in the spread of infectious diseases

2019 ◽  
Author(s):  
Ayesha S. Mahmud ◽  
Md. Iqbal Kabir ◽  
Kenth Engø-Monsen ◽  
Sania Tahmina ◽  
Baizid Khoorshid Riaz ◽  
...  
Keyword(s):  
Infectious Diseases ◽  
Large Scale ◽  
Disease Risk ◽  
Human Mobility ◽  
Mobile Phone Data ◽  
Dhaka City ◽  
Population Mobility ◽  
Time Data ◽  
The Impact

AbstractHuman mobility connects populations and can lead to large fluctuations in population density, both of which are important drivers of epidemics. Measuring population mobility during infectious disease outbreaks is challenging, but is a particularly important goal in the context of rapidly growing and highly connected urban centers in low and middle income countries, which can act to amplify and spread local epidemics nationally and internationally. Here, we combine estimates of population movement from mobile phone data for over 4 million subscribers in the megacity of Dhaka, Bangladesh, one of the most densely populated cities globally. We combine mobility data with epidemiological data from a household survey, to understand the role of population mobility on the spatial spread of the mosquito-borne virus chikungunya within and outside Dhaka city during a large outbreak in 2017. The peak of the 2017 chikungunya outbreak in Dhaka coincided with the annual Eid holidays, during which large numbers of people traveled from Dhaka to their native region in other parts of the country. We show that regular population fluxes around Dhaka city played a significant role in determining disease risk, and that travel during Eid was crucial to the spread of the infection to the rest of the country. Our results highlight the impact of large-scale population movements, for example during holidays, on the spread of infectious diseases. These dynamics are difficult to capture using traditional approaches, and we compare our results to a standard diffusion model, to highlight the value of real-time data from mobile phones for outbreak analysis, forecasting, and surveillance.

The Bioarchaeology of Migration in the Ancient Mediterranean

2021 ◽  
Vol 33 (2) ◽  
pp. 211-241
Author(s):  
Thomas P. Leppard ◽  
Carmen Esposito ◽  
Massimiliano Esposito
Keyword(s):  
Behavioral Change ◽  
Large Scale ◽  
Human Mobility ◽  
Meta Analysis ◽  
Human Movement ◽  
Cultural Effects ◽  
The Mean ◽  
The Mediterranean ◽  
Late Roman Period ◽  
And Migration

The Mediterranean is often regarded as characterized by high levels of human mobility and migration, which are in turn considered to have driven large-scale cultural effects. However, this supposition is problematic, in that it relies on various types of proxy for human movement, rather than on direct bioarchaeological evidence. Accordingly, in this study we attempt to quantify diachronic Mediterranean mobility and migration by undertaking the first meta-analysis of the burgeoning radiogenic isotope datasets now available from the Mediterranean. We gathered 87Sr/ 86Sr data derived from funerary populations from the Neolithic to the late Roman period. We imposed a data-hygiene regime, discarding low-quality, methodologically idiosyncratic, or other potentially erroneous data; this resulted in a cleansed and trimmed dataset (n = 899). Within this dataset, we find that mean rates of post-juvenile migration are relatively low. Utilizing the methodologies specific to individual studies, the mean nonlocal rate is 9.57%. Imposing a standard methodology on the most statistically robust data (resulting in n = 702) allows us to recompute a mean nonlocal rate of 5.84%. In both the data as originally reported and as recomputed, we detect comparatively higher levels of migration in the period 7000–3500 BC, followed by decreasing levels of migration in the later Holocene. We discuss the implications of these results for how we understand longterm cultural and behavioral change in the Mediterranean.

Effective dispersal of large seeds by Baird's tapir: a large-scale field experiment

2011 ◽  
Vol 28 (1) ◽  
pp. 119-122 ◽  
Author(s):  
Georgina O'Farrill ◽  
Sophie Calmé ◽  
Raja Sengupta ◽  
Andrew Gonzalez
Keyword(s):  
Field Experiment ◽  
Large Scale ◽  
Digestive System ◽  
Home Range Size ◽  
Long Distance ◽  
Terrestrial Mammals ◽  
Scale Field ◽  
Large Scale Field ◽  
Viable Seeds

Even though the full process of seed dispersal is the combination of movement mode and distance, deposition, successful germination and survival (Nathan 2006, Westcott et al. 2005), relatively few studies have documented the role of mammals as facilitators of germination and survival (Paine & Harms 2009). In particular, the effectiveness of large terrestrial mammals (>50 kg) as effective dispersers of large seeds is poorly known, but has been linked to the treatment of the seeds in their digestive system, the deposition of viable seeds in nutrient-rich environments (faeces) and favourable sites. Other aspects related to long-distance movements, defecation patterns and home-range size are frequently cited as factors that favour the deposition of seeds far from parent trees, which is expected to reduce predation and intraspecific competition, and enhance fitness (Schupp et al. 2002). We addressed these issues through a large-scale field experiment.

scholarly journals Examining the Limits of Predictability of Human Mobility

Entropy ◽  
2019 ◽  
Vol 21 (4) ◽  
pp. 432 ◽  
Author(s):  
Vaibhav Kulkarni ◽  
Abhijit Mahalunkar ◽  
Benoit Garbinato ◽  
John Kelleher
Keyword(s):  
Long Range ◽  
Upper Bound ◽  
Prediction Models ◽  
Statistical Tests ◽  
Human Mobility ◽  
Network Architectures ◽  
Systematic Bias ◽  
Scale Invariant ◽  
Long Distance ◽  
Shed Light

We challenge the upper bound of human-mobility predictability that is widely used to corroborate the accuracy of mobility prediction models. We observe that extensions of recurrent-neural network architectures achieve significantly higher prediction accuracy, surpassing this upper bound. Given this discrepancy, the central objective of our work is to show that the methodology behind the estimation of the predictability upper bound is erroneous and identify the reasons behind this discrepancy. In order to explain this anomaly, we shed light on several underlying assumptions that have contributed to this bias. In particular, we highlight the consequences of the assumed Markovian nature of human-mobility on deriving this upper bound on maximum mobility predictability. By using several statistical tests on three real-world mobility datasets, we show that human mobility exhibits scale-invariant long-distance dependencies, contrasting with the initial Markovian assumption. We show that this assumption of exponential decay of information in mobility trajectories, coupled with the inadequate usage of encoding techniques results in entropy inflation, consequently lowering the upper bound on predictability. We highlight that the current upper bound computation methodology based on Fano’s inequality tends to overlook the presence of long-range structural correlations inherent to mobility behaviors and we demonstrate its significance using an alternate encoding scheme. We further show the manifestation of not accounting for these dependencies by probing the mutual information decay in mobility trajectories. We expose the systematic bias that culminates into an inaccurate upper bound and further explain as to why the recurrent-neural architectures, designed to handle long-range structural correlations, surpass this upper limit on human mobility predictability.

scholarly journals Human mobility networks and persistence of rapidly mutating pathogens

2017 ◽  
Vol 4 (3) ◽  
pp. 160914 ◽  
Author(s):  
Alberto Aleta ◽  
Andreia N. S. Hisi ◽  
Sandro Meloni ◽  
Chiara Poletto ◽  
Vittoria Colizza ◽  
...  
Keyword(s):  
Phase Space ◽  
Disease Ecology ◽  
Large Scale ◽  
Human Mobility ◽  
Population Level ◽  
Infectious Period ◽  
Acquired Immunity ◽  
Heterogeneous Environment ◽  
Dynamical Regimes

Rapidly mutating pathogens may be able to persist in the population and reach an endemic equilibrium by escaping hosts’ acquired immunity. For such diseases, multiple biological, environmental and population-level mechanisms determine the dynamics of the outbreak, including pathogen's epidemiological traits (e.g. transmissibility, infectious period and duration of immunity), seasonality, interaction with other circulating strains and hosts’ mixing and spatial fragmentation. Here, we study a susceptible-infected-recovered-susceptible model on a metapopulation where individuals are distributed in sub-populations connected via a network of mobility flows. Through extensive numerical simulations, we explore the phase space of pathogen's persistence and map the dynamical regimes of the pathogen following emergence. Our results show that spatial fragmentation and mobility play a key role in the persistence of the disease whose maximum is reached at intermediate mobility values. We describe the occurrence of different phenomena including local extinction and emergence of epidemic waves, and assess the conditions for large-scale spreading. Findings are highlighted in reference to previous studies and to real scenarios. Our work uncovers the crucial role of hosts’ mobility on the ecological dynamics of rapidly mutating pathogens, opening the path for further studies on disease ecology in the presence of a complex and heterogeneous environment.

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