Large-scale spatial network models: An application to modeling information diffusion through the homeless population of San Francisco

2018 ◽  
Vol 47 (3) ◽  
pp. 523-540 ◽  
Author(s):  
Zack W Almquist
Keyword(s):  
San Francisco ◽  
Information Diffusion ◽  
Large Scale ◽  
Homeless Youth ◽  
Network Models ◽  
Cost Effective ◽  
Homeless Population ◽  
Small Scale ◽  
Government Organizations ◽  
Available Information

To address the effects of increasing homeless populations, planners must understand the size and distribution of their homeless populations, as well as how information and resources are diffused throughout homeless communities. Currently, there is limited publicly available information on the homeless population, e.g. the estimates of the homeless, gathered annually by the US Housing & Urban Development point in time survey. While it is theorized in the literature that the networks of homeless individuals provide access to important information for planners in areas such as health (e.g. needle exchanges) or access (e.g. information diffusion about the location of new shelters), it is almost never measured, and if measured, only at a very small scale. This research addresses the question of how planners can leverage publicly available data on the homeless to better understand their own homeless networks (e.g. relations among the homeless themselves) in a cost-effective and reliable way. To this end, we provide a method for simulating realistic networks of a social relation among the homeless population and perform a diffusion analysis over the resultant homeless-to-homeless networks, and also over a simulated homeless youth Facebook network. We validate the former through novel use of historical data, while the latter is based on recent work that demonstrated that the homeless youth have similar size Facebook networks and usage. We see much stronger spatial hopping and quicker diffusion over the youth network, i.e. we expect information to pass among the youth network much faster than the homeless-to-homeless network. This finding implies that non-government organizations and public health efforts that seek to provide information, goods or services to the homeless should start with the homeless youth, given the potential for faster diffusion when homeless youth are the initial transmitters. Overall, these methods and analysis provide a unique opportunity for visualizing, characterizing and inferring information for large-scale and hard to measure social networks.

scholarly journals Cost-effective composite methods for large-scale solid-state calculations

2020 ◽  
Vol 224 ◽  
pp. 292-308
Author(s):  
L. Donà ◽  
J. G. Brandenburg ◽  
I. J. Bush ◽  
B. Civalleri
Keyword(s):  
Solid State ◽  
Large Scale ◽  
Cost Effective ◽  
Small Scale ◽  
Composite Methods

Cost-effective hybrid DFT composite methods allow for large-scale solid-state calculations with small-scale computing resources.

scholarly journals Upstream to downstream: a multiple-assessment-point approach for targeting non-point-source priority management areas at large watershed scale

2013 ◽  
Vol 10 (11) ◽  
pp. 14535-14555
Author(s):  
L. Chen ◽  
Y. Zhong ◽  
G. Wei ◽  
Z. Shen
Keyword(s):  
Point Source ◽  
Large Scale ◽  
Cost Effective ◽  
Small Scale ◽  
Watershed Scale ◽  
Nps Pollution ◽  
Specific Assessment ◽  
High Level ◽  
Multiple Assessment

Abstract. The identification of priority management areas (PMAs) is essential for the control of non-point source (NPS) pollution, especially for a large-scale watershed. However, previous studies have typically focused on small-scale catchments adjacent to specific assessment points; thus, the interactions between multiple river points remain poorly understood. In this study, a multiple-assessment-point PMA (MAP-PMA) framework was proposed by integrating the upstream sources and the downstream transport aspects of NPS pollution. Based on the results, the integration of the upstream input changes was vital for the final PMAs map, especially for downstream areas. Contrary to conventional wisdom, this research recommended that the NPS pollutants could be best controlled among the upstream high-level PMAs when protecting the water quality of the entire watershed. The MAP-PMA framework provided a more cost-effective tool for the establishment of conservation practices, especially for a large-scale watershed.

scholarly journals Community detection in large scale congested urban road networks

PLoS ONE ◽  
2021 ◽  
Vol 16 (11) ◽  
pp. e0260201
Author(s):  
Seyed Arman Haghbayan ◽  
Nikolas Geroliminis ◽  
Meisam Akbarzadeh
Keyword(s):  
San Francisco ◽  
Community Detection ◽  
Traffic Congestion ◽  
Traffic Management ◽  
Large Scale ◽  
Cost Effective ◽  
Computational Time ◽  
Management Tools ◽  
Traffic Condition ◽  
Urban Networks

Traffic congestion in large urban networks may take different shapes and propagates non-uniformly variations from day to day. Given the fact that congestion on a road segment is spatially correlated to adjacent roads and propagates spatiotemporally with finite speed, it is essential to describe the main pockets of congestion in a city with a small number of clusters. For example, the perimeter control with macroscopic fundamental diagrams is one of the effective traffic management tools. Perimeter control adjusts the inflow to pre-specified regions of a city through signal timing on the border of a region in order to optimize the traffic condition within the region. The precision of macroscopic fundamental diagrams depends on the homogeneity of traffic condition on road segments of the region. Hence, previous studies have defined the boundaries of the region under perimeter control subjected to the regional homogeneity. In this study, a cost-effective method is proposed for the mentioned problem that simultaneously considers homogeneity, contiguity and compactness of clusters and has a shorter computational time. Since it is necessary to control the cost and complexity of perimeter control in terms of the number of traffic signals, sparse parts of the network could be potential candidates for boundaries. Therefore, a community detection method (Infomap) is initially adopted and then those clusters are improved by refining the communities in relation to roads with the highest heterogeneity. The proposed method is applied to Shenzhen, China and San Francisco, USA and the outcomes are compared to previous studies. The results of comparison reveal that the proposed method is as effective as the best previous methods in detecting homogenous communities, but it outperforms them in contiguity. It is worth noting that this is the first method that guarantees the connectedness of clusters, which is a prerequisite of perimeter control.

scholarly journals Measuring coral reef decline through meta-analyses

2005 ◽  
Vol 360 (1454) ◽  
pp. 385-395 ◽  
Author(s):  
I.M Côté ◽  
J.A Gill ◽  
T.A Gardner ◽  
A.R Watkinson
Keyword(s):  
Coral Reef ◽  
Large Scale ◽  
Coral Cover ◽  
Meta Analysis ◽  
Cost Effective ◽  
Data Availability ◽  
Small Scale ◽  
Ecological Change ◽  
Live Coral ◽  
Scale Estimate

Coral reef ecosystems are in decline worldwide, owing to a variety of anthropogenic and natural causes. One of the most obvious signals of reef degradation is a reduction in live coral cover. Past and current rates of loss of coral are known for many individual reefs; however, until recently, no large-scale estimate was available. In this paper, we show how meta-analysis can be used to integrate existing small-scale estimates of change in coral and macroalgal cover, derived from in situ surveys of reefs, to generate a robust assessment of long-term patterns of large-scale ecological change. Using a large dataset from Caribbean reefs, we examine the possible biases inherent in meta-analytical studies and the sensitivity of the method to patchiness in data availability. Despite the fact that our meta-analysis included studies that used a variety of sampling methods, the regional estimate of change in coral cover we obtained is similar to that generated by a standardized survey programme that was implemented in 1991 in the Caribbean. We argue that for habitat types that are regularly and reasonably well surveyed in the course of ecological or conservation research, meta-analysis offers a cost-effective and rapid method for generating robust estimates of past and current states.

Facilitating recruitment of Amphibolis as a novel approach to seagrass rehabilitation in hydrodynamically active waters

2010 ◽  
Vol 61 (10) ◽  
pp. 1123 ◽  
Author(s):  
Rachel J. Wear ◽  
Jason E. Tanner ◽  
Sonja L. Hoare
Keyword(s):  
Large Scale ◽  
Spatial Scales ◽  
South Australia ◽  
Cost Effective ◽  
Belowground Biomass ◽  
Small Scale ◽  
Past Century ◽  
Wastewater Management ◽  
Novel Approach ◽  
High Wave Energy

Worldwide, 29% of seagrass habitats have been lost over the past century. Compared with large-scale losses, successful restoration programs are usually only small scale (a few hectares). One area of significant seagrass loss (>5200 ha) is Adelaide, South Australia. Improvements to wastewater management have raised the possibility of rehabilitation in this area. Traditional methods of seagrass restoration are expensive and have had limited success owing to high wave energy. We investigated a range of biodegradable substrates, mostly made of hessian (burlap), to enhance Amphibolis recruitment as an alternative. After 5 weeks, 16 514 seedlings, or 157 seedlings m–2, had recruited. Survival declined over the following 12 months to 31.4%, and down to 7.2% after 3 years, in part as a result of breakdown of the hessian, and the wave-exposed nature of the sites. During the initial 12 months, above- and belowground biomass increased 2.6- and 6.4-fold, respectively. The technique may represent a non-destructive, cost-effective (<AU$10 000 ha–1) method to restore Amphibolis over large spatial scales and in areas that are hydrodynamically too active for traditional techniques, thus helping ameliorate some of the large-scale losses of seagrasses that have occurred globally.

scholarly journals Upstream to downstream: a multiple-assessment-point approach for targeting non-point-source priority management areas at large watershed scale

2014 ◽  
Vol 18 (4) ◽  
pp. 1265-1272 ◽  
Author(s):  
L. Chen ◽  
Y. Zhong ◽  
G. Wei ◽  
Z. Shen
Keyword(s):  
Point Source ◽  
Large Scale ◽  
Cost Effective ◽  
Small Scale ◽  
Nps Pollution ◽  
Specific Assessment ◽  
High Level ◽  
Multiple Assessment

Abstract. The identification of priority management areas (PMAs) is essential for the control of non-point-source (NPS) pollution, especially for a large-scale watershed. However, previous studies have typically focused on small-scale catchments adjacent to specific assessment points; thus, the interactions between multiple river points remain poorly understood. In this study, a multiple-assessment-point PMA (MAP-PMA) framework was proposed by integrating the upstream sources and the downstream transport aspects of NPS pollution. Daning River watershed was taken as a case study in this paper, which has demonstrated that the integration of the upstream input changes was vital for the final PMAs map, especially for downstream areas. Contrary to conventional wisdom, this research recommended that the NPS pollutants could be best controlled among the upstream high-level PMAs when protecting the water quality of the entire watershed. The MAP-PMA framework provided a more cost-effective tool for the establishment of conservation practices, especially for a large-scale watershed.

scholarly journals Sustainable Water Resources Using Corner Pivot Lateral, A Novel Sprinkler Irrigation System Layout for Small Scale Farms

2018 ◽  
Vol 8 (12) ◽  
pp. 2601 ◽  
Author(s):  
Saeed Rad ◽  
Lei Gan ◽  
Xiaobing Chen ◽  
Shaohong You ◽  
Liangliang Huang ◽  
...  
Keyword(s):  
Water Distribution ◽  
Large Scale ◽  
Irrigation System ◽  
Sprinkler Irrigation ◽  
Cost Effective ◽  
System Component ◽  
Small Scale ◽  
Can Technique ◽  
Distribution Uniformity ◽  
And Control

Sprinkler irrigation systems are widely used in medium and large scale farms in different forms. However less types are available to apply in small farms due to their high costs. The current study was done according to a novel cost effective design for a semi-permanent sprinkler irrigation system for small farm owners. The new layout known as Corner Pivot Lateral (CPL) was examined in irrigation test center at Lijian Scientific and Technological Demonstration Park, at Nanning city, China. CPL was implemented without a main/sub mainline pipe, by applying a single pivoting lateral at the corner of the plot that directly connected to the resource to convey water from the pump. The lateral moves around the corner using a rotating elbow in a quadrant pattern manually to cover the entire farm. A conventional semi-permanent system was applied for the same farm as reference. A cost analysis on the required components as well as annual operational costs was carried out for comparison and control. Results showed that a lower system component would be needed for the CPL method. Overall, more than a 15% capital cost reduction with 7% annual cost decrement was achieved for CPL in this experiment comparatively. The Catch can technique was applied to examine the CPL system’s efficiency and 79% water distribution uniformity around the sprinkler was obtained. This new method can encourage small estate holders to switch from traditional to pressurized systems which optimizes water application costs.

scholarly journals Influence network design via multi-level optimization considering boundedly rational user behaviours in social media networks

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Guanxiang Yun ◽  
Qipeng P. Zheng ◽  
Vladimir Boginski ◽  
Eduardo L. Pasiliao
Keyword(s):  
Social Media ◽  
Theoretical Model ◽  
Information Diffusion ◽  
Large Scale ◽  
Heuristic Algorithms ◽  
User Equilibrium ◽  
Propagation Model ◽  
Small Scale ◽  
Social Media Networks ◽  
Game Theoretical Model

AbstractSocial media networks have been playing an increasingly more important role for both socialization and information diffusion. Political campaign can gain more supporters by attracting more mass attention and influencing them directly, while commercial campaigns can increase their companies’ profits by expanding social media connection with new users. To build the optimal network structure to influence the whole, this paper studies mathematical models to simulate the users’ behaviours interacting with others in the information provider’s network. The behaviours of concerns include information re-posting and following/unfollowing other users. Linear threshold propagation model is used to determine the re-posting actions, Boundedly Rational User Equilibrium (BRUE) models are used to determine the following or unfollowing actions. Hence, the topology of the network changes and depends on the information provider’s plan to post various kinds of information. A three-level optimization model is proposed to maximize total number of connections, the goal of the top level. The second level simulates user behaviours under BRUE. The third level maximizes the each user’s utility defined in the second level. This paper solves this problem using exact algorithms for a small-scale synthetic network. For a large-scale problem, this paper uses heuristic algorithms based on large neighbourhood search. This paper also discusses possible reasons why the BRUE model may be a more accurate simulation of users’ actions compared to game theory. Comparisons from the BRUE model to game theoretical model show that the BRUE model performs significantly better than game theoretical model.

scholarly journals SARS-CoV-2-Specific Memory T Lymphocytes From COVID-19 Convalescent Donors: Identification, Biobanking, and Large-Scale Production for Adoptive Cell Therapy

2021 ◽  
Vol 9 ◽  
Author(s):  
C. Ferreras ◽  
B. Pascual-Miguel ◽  
C. Mestre-Durán ◽  
A. Navarro-Zapata ◽  
L. Clares-Villa ◽  
...  
Keyword(s):  
T Cells ◽  
Large Scale ◽  
Memory T Cells ◽  
Adoptive Cell Therapy ◽  
Cost Effective ◽  
Effector Memory ◽  
Small Scale ◽  
Scale Production ◽  
Specific Memory ◽  
Large Scale Production

Syndrome coronavirus 2 (SARS-CoV-2) pandemic is causing a second outbreak significantly delaying the hope for the virus’ complete eradication. In the absence of effective vaccines, we need effective treatments with low adverse effects that can treat hospitalized patients with COVID-19 disease. In this study, we determined the existence of SARS-CoV-2-specific T cells within CD45RA– memory T cells in the blood of convalescent donors. Memory T cells can respond quickly to infection and provide long-term immune protection to reduce the severity of COVID-19 symptoms. Also, CD45RA– memory T cells confer protection from other pathogens encountered by the donors throughout their life. It is of vital importance to resolve other secondary infections that usually develop in patients hospitalized with COVID-19. We found SARS-CoV-2-specific memory T cells in all of the CD45RA– subsets (CD3+, CD4+, and CD8+) and in the central memory and effector memory subpopulations. The procedure for obtaining these cells is feasible, easy to implement for small-scale manufacture, quick and cost-effective, involves minimal manipulation, and has no GMP requirements. This biobank of specific SARS-CoV-2 memory T cells would be immediately available “off-the-shelf” to treat moderate/severe cases of COVID-19, thereby increasing the therapeutic options available for these patients.

scholarly journals Synthesis, Characterization, and Applications of Silver Nano Fibers in Humidity, Ammonia, and Temperature Sensing

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 682
Author(s):  
Haroon-Ur Rashid ◽  
Muhammad Ali ◽  
Mahidur R. Sarker ◽  
Sawal Hamid Md Ali ◽  
Naseem Akhtar ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Large Scale ◽  
Cost Effective ◽  
Device Fabrication ◽  
Temperature Sensing ◽  
Small Scale ◽  
Scale Production ◽  
Sensing Applications ◽  
Large Scale Production ◽  
Response And Recovery

The promising chemical, mechanical, and electrical properties of silver from nano scale to bulk level make it useful to be used in a variety of applications in the biomedical and electronic fields. Recently, several methods have been proposed and applied for the small-scale and mass production of silver in the form of nanoparticles, nanowires, and nanofibers. In this research, we have proposed a novel method for the fabrication of silver nano fibers (AgNFs) that is environmentally friendly and can be easily deployed for large-scale production. Moreover, the proposed technique is easy for device fabrication in different applications. To validate the properties, the synthesized silver nanofibers have been examined through Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-Ray diffraction (XRD). Further, the synthesized silver nanofibers have been deposited over sensors for Relative humidity (RH), Ammonia (NH3), and temperature sensing applications. The sensor was of a resistive type, and found 4.3 kΩ for relative humidity (RH %) 30–90%, 400 kΩ for NH3 (40000 ppm), and 5 MΩ for temperature sensing (69 °C). The durability and speed of the sensor verified through repetitive, response, and recovery tests of the sensor in a humidity and gas chamber. It was observed that the sensor took 13 s to respond, 27 s to measure the maximum value, and took 33 s to regain its minimum value. Furthermore, it was observed that at lower frequencies and higher concentration of NH3, the response of the device was excellent. Furthermore, the device has linear and repetitive responses, is cost-effective, and is easy to fabricate.

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