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A Differential Model Of The Spatial Spread Of Information

A Differential Model Of The Spatial Spread Of Information

They presented a probabilistic viral marketing model and apply the model on a knowledge sharing website. [8] studied the problem of [13] further and presented a greedy heuristics-based approximation algorithm with performance guarantee of 63% out of the optimal. [11] modeled rumor spreading where the population has been divided in three categories: Ignorant, spreaders and Stiflers using a model similar to an epidemiological one. Contact between an ignorant and a spreader could increase the number of spreaders and contact between a spread and a stifler increases the number of stifler, with some probabilities. They performed a systematic study of threshold properties of the diffusion process on different classes of static network. [12] presented a systematic analyses of all the processes related to the diffusion of information ( or innovations) in a social network. He distinguishes the particular roles played by agents in the network according to their positions, elucidated the roles of homophily and heterophily and shows imitation as the principal mechanism for adoption [1] considered time-evolving networks and rumor spreading. In their model, the agents are in a square lattice (grid) and interact with each other through their random movements within the region. They showed that, starting from a single informed agent, the time it takes for information to reach the entire population has a power law distribution with respect to the size of the population and the size of the grid and that the average degree of information depends on the size of the grid. [4] studied the feedback effect of social ties and similarity and their interactions using data from two online communities. They also examined prediction of an individual’s behavior using similarity and the social network formed base on previous interactions and observed that people encounter each other due to over-lap in their interests (similarity) they found that the consequences of these encounters can lead to further similar interests that are visible many months later. In this paper, we examine the spatial spread of an information wave from a population of informed to a population of uninformed individuals and determine a coupled threshold conditions which determine whether information will flow or not and conditions for the existence of such travelling information wave and the speed of propagation. The specific problem we investigate in this paper, is how the population of the uninform class can be reduced when initial homogeneous informed class 𝐼 𝑜 is introduced into the
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The role of geospatial hotspots in the spatial spread of tuberculosis in rural Ethiopia: a mathematical model

The role of geospatial hotspots in the spatial spread of tuberculosis in rural Ethiopia: a mathematical model

Several spatial analyses of TB have identified localized transmission hotspots associated with areas of overcrowding and poverty [14 – 17]. However, the extent to which these geospatial hotspots drive the spatial spread of tuberculosis has not been documented, especially in settings with dispersed population settlements. Although considerable advancements in the methods used to investigate the spatial diffusion of infectious diseases have been made in the last decades [12,18,19], only a few modelling studies were able to apply such methods in the investigation of spatial transmission of TB by incorporating spatial structure. In addition, these studies were limited to overcrowded urban areas [20], and specific cross-border settings [21]. In this study, we aimed to understand the geographical spread of TB from hotspots to regions located at different distances in a remote region of Ethiopia.
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A Model of Spatial Spread of an Infection with Applications to HIV/AIDS in Mali

A Model of Spatial Spread of an Infection with Applications to HIV/AIDS in Mali

In this paper we introduce a classical SI model to capture the spread of an infectious disease within a population. More precisely, the spatial diffusion of HIV/AIDS in a population is modeled. For that, we assume that the spread is due to the anarchical comportment of infected individuals along a road, especially, “lorry drivers”. The question which con- sists of the control of the infection is also addressed. Infected individuals moving from a town to another one, the diffu- sion is then anisotropic with a main direction of propagation, namely the road direction. Using a semi-group argument and a maximum principle, the uniqueness of a solution to the problem is established. This solution is also estimated. We end this paper by considering some numerical experiments in the case of HIV/AIDS spread in Mali along a road con- necting two towns.
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Age specific contacts and travel patterns in the spatial spread of 2009 H1N1 influenza pandemic

Age specific contacts and travel patterns in the spatial spread of 2009 H1N1 influenza pandemic

Though based on simplifying assumption, the model is able to account for the heterogeneities in the spatial distribution of the population, in the mixing patterns and in the travel behavior, and provide a solution to as- sess the risk of a major epidemic. We considered a def- inition for the children age class up to 15 or 18 years old, justified by the available data and statistics, however the approach is transparent to this choice and analo- gous results to the ones presented can be reached by informing the model with a different definition of clas- ses, as long as statistics informing the groups-specific parameters α, ε, η, and r are available. The approach represents a general framework that can be applicable to other case studies and host population partitions that do not depend on age, such as for instance mixing pat- terns and travel behaviors depending on socio- economic aspects, or contact profiles and mobility within specific settings where classes correspond to pro- fessional roles or conditions of individuals (e.g. health- care workers and patients in hospitals).
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A Preliminary Study on Spatial Spread Risk of Epidemics by Analyzing the Urban  Subway Mobility Data

A Preliminary Study on Spatial Spread Risk of Epidemics by Analyzing the Urban Subway Mobility Data

In the history, epidemic has always been a serious threat to human health. The prevention and treatment of epi- demic is always an urgent problem faced by the human being. As the MERS is spreading nowadays, the preven- tion and suppression of similar epidemic is a significant responsibility of the government and the medical de- partment. In the view of system science, the outbreak of epidemic can be understood as a complex diffusion process in the crowd. The modeling and assessment of this process can help us to understand the mechanism of the spread of epidemic and provide corresponding basis of epidemic analysis, simulation and interference [1].
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Temporal and Spatial Spread of an Intersegmental Reflex in Crayfish

Temporal and Spatial Spread of an Intersegmental Reflex in Crayfish

Three observations contradict the hypothesis that some reflex responses are initiated by excitation of receptors located outside the stimulated leg: 1 interruption of all neural connecti[r]

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Causes and Consequences of Spatial Within-Host Viral Spread

Causes and Consequences of Spatial Within-Host Viral Spread

Figure 3. Patterns and dynamics of spatial spread from the ecological literature. (a) Populations expand as a “traveling wave” in a single spatial dimension. (b) Populations expand as a “traveling wave” in two-dimensional space. Figures (a) and (b) reproduced from [63]. (c) When populations expand in two spatial dimensions, the square root of the area that is inhabited is expected to grow linearly in time. Figure reproduced from [64]. (d) Types of density-dependence. Negative density-dependence occurs when per capita growth rates decrease with increases in local population densities. Allee effects occurs when per capita growth rates first increase, and then decrease, with increases in local population densities. Figure reproduced from [65].
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Optimizing the density of Stark decelerated radicals at low final velocities: a tutorial review

Optimizing the density of Stark decelerated radicals at low final velocities: a tutorial review

As Stark decelerators rely on conservative forces, the phase-space volume of the molecule packets cannot be compressed and the decelerator can only preserve the phase-space den- sity of the initial molecular beam. This underlines the necessity to optimize conditions at the source as much as possible to maximize the number density of molecules decelerated to the target velocity. The first step in class I optimization is to optimize the radical source. There are several parameters relating to the initial molecular beam which are relevant for Stark deceleration experiments, primarily its mean velocity v, its velocity spread v (expressed as the full-width-at-half-maximum (FWHM) of the velocity distribution), its longitudinal spatial spread x and its initial radical density n after exiting the valve. These parameters are strongly correlated with each other. It is often difficult or even impossi- ble to tune only one parameter without changing one or all of the others. This imposes challenges to experimentalists, and compromises have to be made to maximize the beam density after deceleration.
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A time series of infectious-like events in Australia between 2000 and 2013 leading to extended periods of increased deaths (all-cause mortality) with possible links to increased hospital medical admissions

A time series of infectious-like events in Australia between 2000 and 2013 leading to extended periods of increased deaths (all-cause mortality) with possible links to increased hospital medical admissions

The increase in deaths is of such a magnitude as to induce a temporary reversal in ongoing reduction in age-standardized mortality. 21,22 Both deaths and medical admissions appear to cluster around a common range of conditions, which could best be described as the exacerbation of existing conditions which are immune sensitive, via infection, inflammation and autoimmunity. 15,20,22-26 The agent appears to show strain specific characteristics, 26-27 and exhibits very small area spread consistent with an infectious etiology. 28-33 Increased hospital bed occupancy also shows spatial spread, 31 and a sudden and unexpected increase in medical bed occupancy is a characteristic feature of these events. 21,34
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Urban Flood Scaling Using Hydrologic and Hydraulic Models with Inception for Early Warning

Urban Flood Scaling Using Hydrologic and Hydraulic Models with Inception for Early Warning

The theme of the study is to establish flood runoff thresholds in the intricate urban catchment, simulate the spatial spread of floodwater using adaptive hydraulic flood propagation models, and develop flood runoff thresholds using modelled flood hydrographs of actual flood events along with simulated flood inundation layers. The next target is to formulate a block for an operational flood forecasting mechanism with ample lead time to assist administrators in flood disaster preparedness using a coupling of hydro-meteorological modelling aided by real- time Doppler Weather Radar (DWR) observations. The application of the USACE Hydrologic Engineering Centre (HEC) models for urban hydrologic analysis [4] has initiated to the development of urban flood models. Water Management Model of United States Environmental Protection Agency (EPA-SWMM) and traditional flood simulation model (FLDSIM) developed by National Institute for Land and Infrastructure Management (NILIM), Japan comprising of (i) MESHSIM to simulate the 2D overland flow using mesh-network and (ii) RIVSIM to simulate the 1D flow through river-network have been used to as an integrated modelling approach to predict flooding on urban basin [5]. Studies have been done on developing an urban flood inundation model by coupling a one- dimensional (1D) model with a two-dimensional (2D) model to overcome the drawbacks of each individual modelling approach, with an additional module to simulate the rainfall-runoff process in urban areas [6]. 2D modelling of floodplain dynamics and rainfall–runoff processes involving urbanized areas are generally hampered by the strong geometrical variability of the urban network cell, inducing an important hydraulic variability. The shallow- water model equations with porosity can be effectively used to account for the reduction in storage and in the exchange sections due to presence of buildings and other structures on the urban floodplains. The introduction of the porosity in the shallow-water equations modifies the expressions for the
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Spatial analysis of falls in an urban community of Hong Kong

Spatial analysis of falls in an urban community of Hong Kong

and 3 points indicates that the result expects 14 clusters to be "real" and one cluster (i.e. 15 observed clusters minus 14 significant clusters) to occur just on the basis of ran- domness. In a real cluster, fall cases occur in temporal and spatial proximity at a higher frequency than by chance. The simulation did not show which clusters were real but it provided a statistical basis to evaluate the number of clusters that did not occur purely by chance. Table 2 also shows that the minimum number of points per cluster must not be too few. The combination of 50 meters and a minimum of 4 or more points, in this case, yields a signif- icantly stable number of 11 real clusters. The same obser- vation applies for those using 100 meter as the threshold distance although all but one of the clusters is real. The Nnh cluster analysis, using a threshold distance of 50 meters and 4 minimum points per cluster, can be taken to the next level to examine the spatial spread of falls by non- spatial characteristics (e.g. age, gender, floor condition, footwear, etc.). Figure 4b shows that six of the eleven clus- ters involved elderly falls. Figure 4c shows that more females than males were involved in the fall hot spots while Figure 4d and Figure 4e show the multi-factorial nature of falls involving a combination of uneven, wet/
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Bluetongue virus spread in Europe is a consequence of climatic, landscape and vertebrate host factors as revealed by phylogeographic inference

Bluetongue virus spread in Europe is a consequence of climatic, landscape and vertebrate host factors as revealed by phylogeographic inference

Our results suggested that BTV spread is facilitated by terres- trial habitat, particularly at low elevation (up to 300 m). These observations are congruent with a barrier effect associated with open ocean and mountains areas, limiting the dispersal of Culicoides vectors. While seas and oceans are hostile habitats for the vector, large populations of species in the Obsoletus com- plex can be found in Europe up to 1000 m [35]. However, areas above 300 m failed to be significantly associated with faster viral diffusion in most of our analyses. This suggests that vector populations at these altitudes either have a lower ability to support virus infection and replication (i.e. a lower compe- tence) and/or exhibit a lower ability to transmit BTV in these environments (i.e. a lower capacity) for example due to lower temperatures or higher wind speeds. Further studies on the competence of the Obsoletus complex are needed to elucidate the change in vector competence and capacity in relation with landscape features. Conflicting results, suggesting a negative
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Comparing the Extend of the Spread Effects: Rural Urban Commuting in Finnish Working Regions

Comparing the Extend of the Spread Effects: Rural Urban Commuting in Finnish Working Regions

As our results show, the development is likely to bring even narrower geographic spread effects if the com- muting costs increase, or if the community structure is controlled, for example, with taxes, to be more stringent. At the moment, the tax deduction of the travel expenses extends about 40 kilometres from the centre and the areas located outside this limit experience higher distance costs than areas located within 40 km from the centre. The high sum of the housing and commuting costs encourage especially low-income households to migrate from remote locations closer to the centre because housing costs are not declined in relation to increased commuting costs. Therefore, it seems that potential spread effects actualize as potential backwash effects in the remote rural areas, and the potential spread effect can work only in the limited rural areas next to the urban core [23] [25]. Thus, remote rural areas have been exposed to negative net migration as earlier studies have shown [12] [26] [27]. This article has focused on Finland but the results can be applied to other similar sparsely-populated re- gions as well with similar physical and institutional settings.
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EIS coordination manuscript-REE revision 6-17

EIS coordination manuscript-REE revision 6-17

Invasive species also impact large spatial areas requiring control actions by multiple affected individuals, e.g., land owners, regional governments, countries (Wilen, 2007). While invasive species control suffers from well-known problems of public good provision (Perrings et al., 2002), the problem is novel in that the supply of the public good (benefits of control that spillover to other individuals) is determined by 1) spatial-dynamic processes unique to each species and 2) the spatial configuration of decision makers. This paper integrates ecological and economic processes to study a spatial externality common in invasive species control decisions made by spatially-connected individuals.
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A novel entomological index, Aedes aegypti Breeding Percentage, reveals the geographical spread of the dengue vector in Singapore and serves as a spatial risk indicator for dengue

A novel entomological index, Aedes aegypti Breeding Percentage, reveals the geographical spread of the dengue vector in Singapore and serves as a spatial risk indicator for dengue

Aedes aegypti BP, reported in the present study was de- veloped using the existing Aedes breeding data obtained through the routine vector surveillance programme in Singapore. As routine larval collection efforts are not uni- form spatially as well as temporally, using the absolute data for risk assessment would be biased. The develop- ment of Ae. aegypti BP takes into consideration the ubi- quitous presence of Ae. albopictus and normalizes the data with the total Aedes breeding sites, which comprises of Ae. aegypti and Ae. albopictus breeding sites. When compared with the traditional Aedes HI, which is reported only on a national level, the main strength of BP is its higher resolution and usefulness for spatial analyses of dengue transmission. We have shown that on a yearly basis, areas with higher BP tend to have higher case count based on historical data. Therefore, BP can be used as a
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Socio Spatial Inequality in Education Facilities in the Concepción Metropolitan Area (Chile)

Socio Spatial Inequality in Education Facilities in the Concepción Metropolitan Area (Chile)

It is possible to make a distinction between arithmetic and proportional equality. Arithmetic equality is referred to a per- fect equality, equality of treatment, where exactly the same amount of benefits is destined to everyone, regardless of the circumstances. Justice assumes an unequal distribution, so its aim is to improve the situation of the most disadvantaged. As postulated by Harvey (1977): “The geographic problem con- sists in elaborating a spatial organization mechanism that maximizes the perspectives of the most disadvantaged region”. For Moreno, the terms of spatial equity and equality are almost synonyms, being differentiated from the justice, because ideal justice consists in the suppression of all disadvantages. In other words, justice encompasses both equality and equity. For this reason, justice mixes both social and spatial features. In other words, involves public authorities to attenuate inequalities and the notion of equality would be mixed with the scope of equity. A similar version was presented by Pitarch Garrido (2000) for the elaboration of planning models of educational services, where five fundamental aspects must be considered, such as social equity, indicating that all public activity must be ad- dressed to whole of the society excluding any discrimination on the basis of social differences. On this basis, education as pub- lic service must look for social equity as a right for every citi- zen. On the other hand, locational equity takes into account that the space always introduces inequalities and therefore, is a con- figurative factor, closely related to social equity.
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A cloud feedback emulator (CFE, version 1.0) for an intermediate complexity model

A cloud feedback emulator (CFE, version 1.0) for an intermediate complexity model

3.3 Radiative balance in CFE LGM simulations For the CFE LGM simulations, we calculate TOA short- wave and longwave radiative-temperature response at equi- librium conditions, averaged over the last 100 years of the LGM and ctlLGM experiments. Note that in this case the shortwave fluxes include forcing from prescribed ice sheets and therefore are not strictly speaking feedbacks. CFE gen- erally captures the spread of the shortwave and longwave radiative-temperature response from the GCMs although it is slightly reduced (Fig. 6). The total imbalance seems to be smaller in CFE compared with most GCMs indicating that CFE is closer to equilibrium, perhaps because it was inte- grated longer. Thus, a larger remaining imbalance could con- tribute to the larger spread in the GCMs compared with CFE. The absolute magnitude of the radiative-temperature re- sponse is mostly reduced in the CFE relative to the GCM simulations. Similar to the 4×CO 2 results, the IPSL-based
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Uncertainty in Lagrangian pollutant transport simulations due to meteorological uncertainty from a mesoscale WRF ensemble

Uncertainty in Lagrangian pollutant transport simulations due to meteorological uncertainty from a mesoscale WRF ensemble

Hegarty et al. (2013) showed that differences between LPDMs are much smaller than differences between mete- orological models, pointing out the fact that uncertainties most likely arise from the meteorological models when La- grangian models are used. The propagation of uncertainty from meteorological fields through an LPDM was addressed by Lin and Gerbig (2005) for horizontal wind uncertainty, and by Gerbig et al. (2008) for uncertainty in vertical mix- ing. In both cases, they found that failing to account for meteorological uncertainty produced backward simulations with insufficient dispersion. They pointed out the impor- tance of spatial correlation in the random errors. All errors were assumed to be random; that is, biases were not ad- dressed. Numerical uncertainties, especially those due to ter- rain, were addressed by Brioude et al. (2012). Meteorolog- ical performance of a group of regional air quality models was evaluated by Vautard et al. (2012). Ensemble forecasts were used to evaluate ozone predictability in Texas by Zhang et al. (2007). Locatelli et al. (2013) used several different global meteorological and transport model pairs to evalu- ate uncertainty in methane inversions, finding large uncer- tainties at regional and smaller scales. Several recent studies (Chevallier et al., 2010; Houweling et al., 2010; Kretschmer et al., 2012; Lauvaux and Davis, 2014) used small numbers of models or configurations of one model to evaluate un- certainties in carbon dioxide (CO 2 ) simulations. Of these,
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Quantifying the spatial dimension of dengue virus epidemic spread within a tropical urban environment

Quantifying the spatial dimension of dengue virus epidemic spread within a tropical urban environment

Sequential transmission (i.e., the progressive occurrence of human cases in neighboring houses), likely attributable to mosquito-driven spread and/or short-distance mobility of viremic humans, as well as long distance propagation of infection (likely generated by human mobility) have been documented in many urban dengue epidemics [21,22,42]. Neff et al [21] elegantly showed how, after the introduction of dengue in a Puerto Rican village, subsequent cases occurred ‘‘sequentially’’ within the same block and also in distant parts of the village. Similarly, phylogenetic analysis of a DENV-3 epidemic affecting the city of Sao Paulo (Brazil) allowed Mondini et al. [25] to estimate the most likely route of viral dispersal, showing that a same lineage was ‘‘dispersed’’ within the city both at short and long distances compatible with mosquito- and human-mediated virus spread, Figure 4. Significant space-time clustering (assessed by the Knox test) of dengue cases in the city of Cairns, Australia, during January–August 2003. Red circles and numbers identify each individual space-time cluster. Detailed information about each cluster can be found in Table 2.
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A Space/Fast-Time Adaptive Monopulse Technique

A Space/Fast-Time Adaptive Monopulse Technique

Both employ a tap-centered configuration with three sets of range constraints about the look direction. STDAE is plotted versus the number of taps in the processor. The solid and dash-dotted line curves indicate performance for the fully constrained and unity gain SFT processors, respectively. A horizontal dashed line indicates the performance of the spa- tially adaptive processor. The plot suggests that a 22-tap fully constrained SFT processor is necessary to achieve the same level of angle estimation performance as the spatially adap- tive processor. As noted before, this is a necessary cost in- curred for maintaining the spatial response at tap T 0 of the
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