Spelling suggestions: "subject:"anda gravity model"" "subject:"anda gravity godel""
171 |
The economic effects of ASEAN integration : three empirical contributions from the perspective of the new economic geography / Les effets économiques de l'intégration de l'ASEAN : trois contributions empiriques de la perspective de la nouvelle économie géographiquePremchit, Walliya 20 September 2013 (has links)
Cette thèse comprend trois études sur l’impact de l’intégration commerciale et de la libéralisation des investissements de l’ASEAN suivant les recherches empiriques de la Nouvelle Économie Géographique (NEG). Les stratégies empiriques consistent à mesurer des coûts de commerce, l’accès au marché ainsi qu’à estimer les modèles de gravité théorique. La première étude examine le progrès de l’intégration commerciale et leur impact sur la performance exportatrice. La deuxième étude voit comment la libéralisation commerciale croissante affecte les inégalités régionales. La troisième étude examine l’impact des accords d’investissement sur l’attractivité des IDE des pays de l’ASEAN. Ces résultats mettent en lumière les avantages et défis de la Communauté Économique de l’ASEAN qui aura lieu à la fin de 2015. / This thesis concerns three studies on the impact of ASEAN trade integration and investment liberalization following empirical research agenda of the new economic geography (NEG). Empirical strategies deal with measuring trade costs, market access and the estimation of modern gravity models. The first study evaluates trade integration progress in ASEAN and its impact on export performance with help of trade costs and market access indicators. The second study examines how improved market access, though deepening trade liberalization, can impact regional inequality. The third study investigates the impact of investment agreement on FDI attractiveness of the ASEAN countries. The results help shed light on potential benefits and challenges ahead of the upcoming ASEAN Economic Community at the end of 2015.
|
172 |
Análisis del impacto de medidas no arancelarias en las exportaciones de uvas frescas peruanas hacia Estados Unidos en el marco del APC Perú-EE. UU, durante los años 2008-2020Felix Limas, Maria Del Pilar, Leon Espino, Pedro Franco 18 August 2021 (has links)
El comercio internacional actualmente es uno de los pilares de la economía mundial brindando ventajas a los países permitiendo que tengan una mayor oferta exportable lo cual se refleja en la mejora de sus ingresos. En el caso Perú y Estados con la implementación y firma del Tratado de Libre Comercio se logro un mayor acceso de productos entre estos lo agrícolas, los que principalmente destacan frente a la competencia.
El trabajo de investigación busca determinar el impacto de las medidas no arancelarias en las exportaciones de uvas frescas peruanas hacia Estados Unidos en el marco del APC Perú-EE. UU, durante los años 2008-2020. En los últimos doce años las exportaciones de uvas frescas han crecido de manera constante, por lo cual existen algunos factores que han sido determinantes para este desarrollo. La investigación tiene como fin conocer como las medidas no arancelarias como las MSF, las OTC y los certificados de calidad han influido en estas exportaciones. Para esto se realizará análisis de tipo mixto, estudiando las tres variables mencionadas con dos tipos de enfoque. En primer lugar, el enfoque cualitativo, para el cual se realizaron entrevistas semi estructuradas con expertos en el sector agroexportador, empresas exportadoras de uvas frescas e instituciones gubernamentales. En segundo lugar, para el enfoque cuantitativo se desarrolló un modelo de gravedad utilizando datos obtenidos de BCRP, PROMPERU, entre otros. El resultado de ambos análisis dio como resultado que las medidas no arancelarias en cuestión influyen de manera positiva a las exportaciones de uvas frescas. / International trade is currently one of the pillars of the world economy, providing advantages to countries allowing them to have a greater exportable supply, which is reflected in the improvement of their income. In the case of Peru and the States, with the implementation and signing of the Free Trade Agreement, greater access to products was achieved, including agricultural products, which mainly stand out against the competition. The research work seeks to determine the impact of non-tariff measures on exports of fresh Peruvian grapes to the United States within the framework of the Peru-US APC. UU, during the years 2008-2020. In the last twelve years, exports of fresh grapes have grown steadily, which is why there are some factors that have been determining factors for this development. The purpose of the investigation is to know how non-tariff measures such as SPS, OTC and quality certificates have influenced these exports. For this, a mixed type of analysis will be carried out, studying the three variables mentioned with two types of approach. First, the qualitative approach, for which semi-structured interviews were conducted with experts in the agro-export sector, fresh grape export companies and government institutions. Second, for the quantitative approach, a gravity model was developed using data obtained from BCRP, PROMPERU, among others. The result of both analyzes showed that the non-tariff measures in question positively influence exports of fresh grapes. / Tesis
|
173 |
Essays on regional trade agreements and international trade / Essais sur les accords commerciaux régionaux et le commerce internationalNguyen, Duc Bao 08 November 2019 (has links)
Cette thèse s’inscrit dans le contexte de prolifération des accords commerciaux régionaux (ACR) et traite des effets des ACR sur le commerce international. Nous visons à mieux comprendre et à apporter des points de vue nouveaux sur le rôle des ACR et du régionalisme en général en tant qu’élément important de la politique commerciale international aujourd’hui. Dans le premier chapitre, nous revisitons les effets ex post des ACR sur le commerce des pays membres et le commerce extrabloc en adoptant une approche empirique. Nous cherchons à déterminer la manière dont les blocs commerciaux régionaux affectent le commerce non seulement entre pays membres mais aussi entre pays membres et pays extérieurs à l’accord. Notre analyse confirme que les ACR augmentent de manière significative le commerce intra-bloc ; néanmoins, dans de nombreux cas, les ACR impliquent des effets de détournement d’échanges qui sont préjudiciables au reste du monde. Le chapitre deux examine de quelle manière la période de mise en œuvre de l’accord et les niveaux de développement des pays membres déterminent, en dynamique, l’effet des ACR sur le commerce international. Nous obtenons des tendances distinctes des effets ex post de l’ACR sur le commerce entre les accords Nord-Nord, Sud-Sud et Nord-Sud. Nous vérifions empiriquement que les ACR conclus par des partenaires commerciaux ayant un statut de développement économique analogue (les accords Nord-Nord ou Sud-Sud) sont susceptibles d’engendrer une augmentation plus forte du commerce des membres pendant une période de mise en œuvre plus courte. Le chapitre trois porte sur la manière dont les interactions entre ACR et développement financier influencent les flux d'échanges entre partenaires commerciaux. Dans ce travail conjoint avec Anne-Gaël Vaubourg, nous montrons que le développement financier (particulièrement sous sa forme intermédiée) encourage les échanges commerciaux mais que cet effet est atténué dès lors que les partenaires commerciaux ont signé un ACR. / The subject of this dissertation focuses on the analysis of different aspects of the relationship between regional trade agreements (RTAs) and the multilateral trading system. We aim to provide a fresh understanding and views of the role of RTAs and regionalism in general as an important feature of international trade policy today. In chapter one we revisit the ex post effects of RTAs on member countries’ trade and extrabloc trade by adopting an empirical approach. We explore how regional trading blocs have influenced trade among members as well as trade with nonmembers. Our analysis confirms the widespread trade-enhancing effects of RTAs on member countries’ trade; however, in many cases, they lead to trade diversion effects that are detrimental to the rest of the world. Chapter two takes a closer look at how the implementation period of trade liberalization and partners’ levels of development affect the RTA dynamic effects on trade over time. We obtain distinct patterns of ex post RTA effects on trade across North-North RTAs, South-South RTAs and North-South RTAs. We empirically validate that RTAs formed by trading partners experiencing similar economic development status (North-North RTAs or South-South RTAs) are likely to lead to a larger increase in members’ trade during a shorter implementation period. Chapter three studies the mechanism through which RTAs impact the effect of financial development on trade flows between exporting and importing countries. In this joint work with Anne-Gaël Vaubourg, we show that the trade-enhancing role of financial development in the exporting country—especially through intermediated finance—is mitigated when there is an RTA between this country and its trading partner.
|
174 |
Home is where the heart is? How regional identity hinders internal migration in GermanyKremer, Anna 18 September 2020 (has links)
People are emotional about places. I study the effect of regional identity (“at home”) on internal migration flows in Germany between 1995 and 2017. Regional identity is proxied by measuring how NUTS3 regions were historically affiliated in the former patchwork of Germany.
When controlling for the influence of distance, culture (measured by dialects) and regional characteristics, I confirm that regional identity drives migration patterns additionally. Employing the separation effect by the German wall affirms that not only earlier migration or family bonds determine movements instead of regional identity.
|
175 |
Konceptuellt ramverk för lagerlokalisering : – En kvalitativ studie om lagerlokalisering / Conceptual Framework for choosing Warehouse Location : -An qualitative study about warehouse locationMalmerberg, Jacob January 2012 (has links)
Bakgrund: Globalisering har gjort försörjningskedjan till ett komplicerat nätverk med många påverkande faktorer. I försörjningskedjan är valet av anläggningars position viktigt för att företag ska behålla sin konkurrenskraft. Valet av lagerlokalisering har stor påverkan på ett företags framgång. Problem: Lagerlokalisering är en komplex process med många faktorer som påverkar, att praktiskt tillämpa existerande modeller är komplicerat. Det saknas ett konceptuellt ramverk för lagerlokalisering. Syfte: Syfte med examensarbetet är att skapa en konceptuell modell för beslutsfattandet för lagerlokalisering för mindre företag, att finna relevanta faktorer samt att praktiskt göra en förstudie för ett företag med verksamhet i Norra Europa. Beräkningar i rapporten är på transportkostnad, lagerkostnad, personalkostnad. Transporttid och kultur är två inre faktorer som tas hänsyn till. Metod: Metodiken i arbetet sker genom en omfattande litteraturstudie, kvalitativa intervjuer med företaget och externa företag för förståelse och beräkningar. Beräkningar grundas i tyngdpunktsmodellen. Avgränsningar: Casestudien är en förstudie med jämförelse mellan Sverige, Polen och Holland. Fokus ligger på lagerlokalisering, således är inte lagereffektivitet inkluderad. Resultat: Ett konceptuellt ramverk presenteras med 3 huvudfaktorer; Strategi, Ekonomi och Miljö som leder till att beslut kan tas kring lagerlokalisering och flera inre faktorer. Huvudfaktorerna visar generella faktorer som lagerlokalisering måste ta hänsyn till. De inre faktorerna är faktorer som ett företag måste prioritera vilka som ska analyseras. Resultatet av casestudien visar att transportkostnad är den största kostnadsposten samt att personalkostnad och lagerkostnad är stora poster i Sverige men relativt sett små vid lagerlokalisering i Polen. Optimala platsen för Hydroscand att placera ett centrallager är i nuläget, enligt tyngdpunktsmetoden, i Örebro men med hänsyn till omsättningstillväxt i Östeuropa förflyttas tyngdpunkten mot Stockholm. Det är stor skillnad i kulturen mellan Polen och Sverige vilket visar på att det krävs annat ledarskap i Polen. Slutsats: Ett konceptuellt ramverk har gjorts som är applicerbar även praktiskt. Ramverket står inte för sig själv utan kräver kompetens inom lagerlokalisering samt övriga modeller. Den ger en bra grund för lagerlokalisering. Casestudien resulterar i material som ger grund till beslut om fortsatta analyser med lagerlokalisering. Praktisk påföljd: Studien resulterar i ett ramverk som är praktiskt användbart för personer och företag som ska se över lagerlokalisering samt redovisar en jämförelse mellan tre olika länder. Ramverket och studien ger en bra grund för fortsatta analyser. Fortsatta studier: Fortsatt forskning bör ske inom praktiskt tillämpbara metoder för valet av lagerlokalisering. Att reda i vilka modeller som lämpas i olika stadier för företag? Vilka modeller används praktiskt av företag?. / Background: Globalization has made the supply chain into a complex network with many different factors involved. The design of the supply chain and warehouse location is important for the competitiveness of a business. Choosing warehouse location has a major impact on a company’s success. Problem: The decision-making of the warehouse location is a complex process with many influential factors which implicates that effectively applying existing models is complicated. There is lack of a conceptual framework for the decision-making of choosing warehouse location. Objective: The aim for this study is to create a conceptual model for decision-making of choosing warehouse location, finding the key factors and to do a real-life feasibility study for a company with operations in Northern Europe. Calculations are made on the transportation cost, inventory cost, personnel cost. Transportation and culture are two internal factors also taken into account. Methodology: The methodology of the study is through a literature review, qualitative interviews with the case company, and other companies for understanding and calculations. Calculations are based on the gravity model. Boundaries: The case study is a feasibility study with comparisons between Sweden, Poland and Holland. The focus is on warehouse location, thus warehouse efficiency is not included. Results: A conceptual framework is presented with three main factors: Strategy, Economics and Environment. The main factors are general factors whereas the internal factors are more specific. The main factors are always taken into consideration while the internal factors must be prioritized, since there are too many. The further a company is to making the decision; more internal factors must be taken into account. The outcome of the feasibility study shows that the transportation costs are the largest cost unit for all of the countries. Personnel and inventory cost are major cost units in Sweden, but relatively small in Poland. The Optimal location for a central warehouse to the case company is currently Örebro, according to the gravity model. As sales grow in Eastern Europe, the optimal location is moved towards Stockholm. There are differences in culture between Poland and Sweden, which indicates the need for different leadership style in Poland. Conclusion: A conceptual framework has been made that can be applied to a real case. The framework requires some understanding of the process of choosing location for a warehouse since it does not stand on its own. There are other models to be use by combining this framework with others. The framework gives a good basis in the decision-making process of choosing warehouse location. The case study results in material that provides the basis for decisions on further analysis of warehouse location. Practical implications: The study results in a framework that is practical for individuals and companies to review warehouse location, and presents a comparison of three different countries. The framework and the study provide a good basis for further analysis. Further research: Further research should be done within practically applicable methods for the selection of warehouse location. To find out which models apply at different stages of business? What models are used in practice by companies?
|
176 |
MARITIME SHIPPING IN INTERNATIONAL TRADEManuel Ignacio I Jimenez Useche (16378074) 15 June 2023 (has links)
<p>Maritime shipping is the most important mode of transportation for international trade. About 70 to 80 percent of the value traded worldwide moves by sea [1]. An inherent problem in global shipping markets is that non-competitive pricing behavior among carriers is widely believed to raise the cost of freight [2]–[5]. It is also likely that the effects of this problem on international trade flows and welfare are magnified by restricted cabotage reservation schemes. Historically, countries have implemented such policies to prohibit foreign competition in domestic shipping markets. The effects of protection on international goods trade are reasonably well understood. The effects of protection on service trade are less straight-forward. Issues of quality become more important, but they are challenging to measure. Moreover, most of these cabotage reservation schemes ban service imports. Therefore, this makes it complicated to compare domestic and foreign services in the same market, given that service activities are place-specific. </p>
<p><br></p>
<p>In order to better understand the effect of non-competitive pricing behavior in global shipping markets on international trade flows and the incidence of cabotage reservation schemes in shipping markets, I develop three essays. In the first Essay I focus on quantifying the economic effects of non-competitive pricing behavior in the maritime shipping industry on (1) freight costs, (2) international trade flows, and (3) economic welfare. The research question that I answer is: what share of observed shipping freight charges is attributable to non-competitive pricing behavior in maritime shipping markets? I estimate the maritime shipping mark-ups applying the method of Atkin and Donaldson [6] to U.S. Census import data of shipments moved by sea during the period 2002-2017. I find that freight mark-ups account for approximately one-third of total freight charges in U.S. imports. Carriers’ mark-ups thus represent an equivalent ad valorem tariff of 1.4-2.6 percent. U.S. imports of differentiated products would be 4.2 to 11.6 percent higher if these mark-ups were eliminated. The cost of these mark-ups in terms of economic welfare for U.S. consumers represents an annual reduction of 0.1-0.2 percent of their real income. Carriers also charge higher maritime shipping mark-ups (per kg.) to high-value products, products with a lower elasticity of substitution, and products with higher import tariffs. Imported products from developing countries or from distant countries to the U.S. are also charged with larger tariff equivalent mark-ups. </p>
<p><br></p>
<p>In the second Essay I estimate the economic burden placed on Puerto Rico by the Jones Act. Using Lloyd’s List Intelligence (LLI) data to document the supply of shipping services in the U.S. -Puerto Rico shipping market, I find that the Jones Act fleet serving Puerto Rico contains no ships designed for the purpose of moving general cargo or bulk commodities. I then evaluate how this lack of supply of shipping services is a burden on imports of goods that would normally travel by ships of those kinds, modelling Puerto Rico’s import demand in a gravity framework. This exercise indicates that Puerto Rico’s demand for final goods exhibits a greater substitution towards non-U.S. sources among products that tend a) to be shipped by sea, b) to be physically heavy, and c) not to be moved in containers. I then estimate a structural gravity model to quantify the tariff-equivalent trade costs the Jones Act imposes on U.S. shipments. This model yields that the Jones Act represents a tariff equivalent of 30.6 percent on average across products. Finally, I use these estimates to calculate the compensating variation of Jones Act removal. I find that the cost of final expenditure in Puerto Rico would be $1.4 billion (about 1.3 percent) lower per year without the Jones Act. </p>
<p><br></p>
<p>Finally, in the third Essay I investigate what specifically explains the estimated change in Puerto Rico’s import demand for U.S. products due to the Jones Act. I use detailed data of vessels’ ports-of-call in the Caribbean from LLI to document issues of service quality and availability in maritime shipping services between the U.S. and Puerto Rico during the period 2004-2020, calculating metrics for some quality dimensions (e.g., vessels age, shipping capacity, shipping frequency and more). I also evaluate market conditions such as the concentration level in the market of carriers and shipyard building companies in order to examine the presumed incidence in shipping freight costs. Additionally, I use Puerto Rico’s import data from the Instituto de Estadísticas de Puerto Rico (IEPR) to evaluate how much the Jones Act restrictions affect the mode choice decisions for shipping products between U.S. mainland and Puerto Rico. The research question that I try to answer is: what is the level and evolution of the quality of shipping services provided by Jones Act-compliant vessels in the U.S.-Puerto Rico shipping market? </p>
|
177 |
How to make the most of open data? A travel demand and supply model for regional bicycle paths / Hur får man ut det mesta av öppna data? En modell för utbud och efterfrågan för planering av regionala cykelvägarCazor, Laurent January 2021 (has links)
Detta examensarbete syftar till att svara på ett av Trafikverket fastställt problem: en gemensam regional cykelplanerings process skulle göra dem billigare och mer jämförbara. De erbjuder för närvarande planerarna en modell som utvecklades av Kågeson 2007. Denna modell har formen av en rapport som ger råd om när man ska bygga en cykelväg mellan städer eller platser i en region. Ändå används den bara i endast 6 av de 21 svenska länen. Trafikverket kräver ett nytt planeringsstödverktyg, mer interaktivt och komplett än Kågeson-modellen. Några nya önskade funktioner är separationen av efterfrågan per syfte, införandet av e-cyklar, olika resesyfte och en prioritering av investeringarna. Examensarbetet är att designa och implementera det här verktyget, även kallat Planning Support System (PSS), som syftar till att jämföra utbud och efterfrågan på cykelväg till prioritering av infrastrukturförbättringar. En huvudbegränsning för modellen är att den måste vara billig datavis, men så komplett och exakt som möjligt. Det baseras på flera öppna dataleverantörer, till exempel OpenStreetMap, den svenska nationella vägdatabasen (NVDB) eller reseundersökningar från Sverige och Nederländerna. Resultatet är en modell, uppdelad efter turändamål och typ av cykel. Del för efterfrågeuppskattning anpassar en klassisk fyrsteg transportmodell till cykelplanering och begränsad data. För olika resändamål genereras och distribueras resor tack vare en ursprungs begränsad gravitationsmodell. Valet av cykelläge är anpassat till det faktiska resebeteendet genom logistisk regression med en binär logit-modell. Resorna tilldelas sedan nätverket med tilldelnings metoden "allt-eller-ingenting" genom Dijkstras algoritm. För att utvärdera cykelförsörjningen använde vi ett mått som heter Level of Traffic Stress (LTS), som uppskattar den potentiella användningen av en nätverkslänk för olika delar av befolkningen som en funktion av vägnätvariablerna. Prioriteringsrankningen är då förhållandet mellan mått på efterfrågan och utbud. Detta nya verktyg implementeras med opensource Geographic Information System (GIS) som heter QGIS och med Python 3 och testas i Södermanlands län / This Master Thesis main objective is to answer a problem set by the Swedish Transport Administration: a common regional bicycle planning process would them cheaper and more comparable. They currently offer the planners a model developed by Kågeson in 2007. This model takes the form of a report which advises on when to build a bicycle path between cities or places of a region. Still, it is only used in only 6 of the 21 Swedish counties. Trafikverket requires a new planning support tool, more interactive and complete than the Kågeson model. Some new desired features are the separation of demand per purpose, the inclusion of e-bikes, different trip purposes, and a prioritization of the investments. The Degree Project work is to design and implement this tool, also called Planning Support System (PSS), which compares supply and demand for bicycle path to prioritizing infrastructure improvements. A main constraint for the model is that it needs to be cheap data-wise, but as complete and precise as possible. It bases on several open data providers, such as OpenStreetMap, the Swedish National Road Database (NVDB), or Travel Surveys from Sweden and the Netherlands. The result is a model, disaggregated by trip purpose and type of bicycle. The demand estimation part adapts a classic four-step transportation model to bicycle planning and limited data. For different trip purposes, trips are generated and distributed thanks to an origin-constrained gravity model. Bicycle mode choice is fit to actual travel behaviour through logistic regression with a binary logit model. The trips are then assigned to the network using the "all-or-nothing" assignment method through the Dijkstra algorithm. To evaluate bicycle supply, we used a metric called Level of Traffic Stress (LTS), which estimates the potential use of a network link by different parts of the population as a function of the road network variables. The prioritization ranking is then the ratio between demand and supply metrics. This new tool is implemented with the opensource Geographic Information System (GIS) called QGIS and with Python 3, and it is tested on Södermanland County.
|
178 |
Assessment of the Potential of Proposed Stations of the California High-Speed Rail As Major Hubs for Physical and Economic DevelopmentColeman, Seitu Akira 01 June 2018 (has links) (PDF)
This study investigated the potential for development of station catchment areas around the proposed California High-Speed Rail System. The study was prompted by a review of practices of Japanese railway company groups that engage not only in train operations, but also in business diversification and property development within the station areas of their lines. These actions allow the company groups to diversify their revenues streams, increase ridership on their lines, and operate as a whole with net profits. This is in contrast to transit agencies in the United States, which only focus on transporting passengers along their lines and do not engage in other commercial activities. This situation limits the potential for transit in the United States to play a larger role in urban transportation.
With the implementation of the California High-Speed Rail System, an opportunity exists to introduce the commercial transit model seen in Japan to the United States. Since the California High-Speed Rail System is a brand-new system with few entrenched interests to impede change, it has the potential to lead as an example of transit operating with net profits and providing additional benefits to the station areas it serves.
However, since planning for station areas to turn into commercially successful activity centers is still a new concept and practice in the United States, a methodology has to be developed to assess the potential for development of station areas. This study set out to answer the two questions: 1) To what extent are the locations of the California High-Speed Rail System’s planned stations currently attractive to development within their respective contexts? 2) Given the information gathered from the study, what policies should be taken to enhance the future development potential of the California High-Speed Rail System’s planned stations as activity centers within their respective station areas?
The potential for development was quantified by calculating accessibility indices for each station catchment area using the inputs of number of jobs, population size, and number of housing units within a gravity model.
The results of the analysis indicate that the station areas at the ends of the alignment in the San Francisco Bay Area and the Los Angeles Metropolitan Area will benefit the most. The next biggest beneficiaries are the major population centers in the San Joaquin Valley, which are Fresno and Bakersfield. Other stations that are not likely enjoy the benefits of a high-speed rail connection as much as other stations are those that have very little development around them currently, such as Kings Tulare and Madera.
However, the potential exists for all stations to enjoy substantial development opportunities if the proper plans, policies, and business strategies are implemented early on and at the corridor level to make the station areas attractive for development. The study makes the following recommendations: Promote the commercialization of train operations and station areas to capitalize on their long-term economic value; Integrate the planning, construction, ownership, and management of train operations and station area development and services to reduce transaction costs; Develop plans or business strategies for each station area to create roadmaps and timelines for their development; And plan for land use activities at station areas on a corridor level to capitalize on specific synergies between station origin-destination pairs (e.g., land use activities that accommodate long-distance travelers between the San Francisco Bay Area and the Los Angeles Metropolitan Area, or those that accommodate commuter needs between up-and-coming station areas in the San Joaquin Valley with major job centers).
|
179 |
Identification of spatiotemporal nutrient patterns and associated ecohydrological trends in the tampa bay coastal regionWimberly, Brent 01 May 2012 (has links)
Improvements for environmental monitoring and assessment were achieved to advance our understanding of sea-land interactions and nutrient cycling in a coastal bay.; The comprehensive assessment techniques for monitoring of water quality of a coastal bay can be diversified via an extensive investigation of the spatiotemporal nutrient patterns and the associated eco-hydrological trends in a coastal urban region. With this work, it is intended to thoroughly investigate the spatiotemporal nutrient patterns and associated eco-hydrological trends via a two part inquiry of the watershed and its adjacent coastal bay. The findings show that the onset of drought lags the crest of the evapotranspiration and precipitation curve during each year of drought. During the transition year, ET and precipitation appears to start to shift back into the analogous temporal pattern as the 2005 wet year. NDVI shows a flat receding tail for the September crest in 2005 due to the hurricane impact signifying that the hurricane event in October dampening the severity of the winter dry season in which alludes to relative system memory. The k-means model with 8 clusters is the optimal choice, in which cluster 2 at Lower Tampa Bay had the minimum values of total nitrogen (TN) concentrations, chlorophyll a (Chl-a) concentrations, and ocean color values in every season as well as the minimum concentration of total phosphorus (TP) in three consecutive seasons in 2008. Cluster 5, located in Middle Tampa Bay, displayed elevated TN concentrations, ocean color values, and Chl-a concentrations, suggesting that high colored dissolved organic matter values are linked with some nutrient sources. The data presented by the gravity modeling analysis indicate that the Alafia River Basin is the major contributor of nutrients in terms of both TP and TN values in all seasons. Such ecohydrological evaluation can be applied for supporting the LULC management of climatic vulnerable regions as well as further enrich the comprehensive assessment techniques for estimating and examining the multi-temporal impacts and dynamic influence of urban land use and land cover.
|
180 |
Novel Applications of Geospatial Analysis in the Modeling of Infectious DiseasesTelionis, Pyrros A. 08 May 2019 (has links)
At the intersection of geography and public health, the field of spatial epidemiology seeks to use the tools of geospatial analysis to answer questions about disease. In this work we explore two areas: the use of geostatistical modeling as an extension of niche modeling, and the use of mobility metrics to augment modeling for epidemic responses.
Niche modeling refers to the practice of using statistical methods to relate the underlying spatially distributed environmental variables to an outcome, typically presence or absence of a species. Such work is common in disease ecology, and often focuses on exploring the range of a disease vector or pathogen. The technique also allows one to explore the importance of each underlying regressor, and the effect it has on the outcome. We demonstrate that this concept can be extended, through geostatistical modeling, to explore non-logistic phenomena such as incidence. When combined with weather forecasts, such efforts can even predict incidence of an upcoming season, allowing us to estimate the total number of expected cases, and where we would expect to find them. We demonstrate this in Chapter 2, by forecasting the incidence of melioidosis in Australia given weather forecasts a year prior. We also evaluate the efficacy of this technique and explore the impact of environmental variables such as elevation on melioidosis.
But these techniques are not limited to free-living and vector-borne pathogens. We theorize that they can also be applied to diseases that spread exclusively by person-to-person contact. Exploring this allows us to find areas of underreporting, as well as areas with unusual local forcing which might merit further investigation by the health department. We also explore this in Chapter 4, by relating the incidence of hepatitis C in rural Virginia to demographic data.
The West African Ebola Outbreak of 2014 demonstrated the need to include mobility in predictive disease modeling. One can no longer assume that neglected tropical diseases will remain contained and immobile, and the assumption of random mixing across large areas is unwise. Our efforts with modeling mobility are twofold. In Chapter 3, we demonstrate the creation of mobility metrics from open source road and river network data. We then demonstrate the usefulness of such data in a meta-population patch model meant to forecast the spread of Ebola in the Democratic Republic of Congo. In Chapter 4, we also demonstrate that mobility data can be used to strengthen outbreak detection via hotspot analysis, and to augment incidence models by factoring in the incidence rates of neighboring areas. These efforts will allow health departments to more accurately forecast incidence, and more readily identify disease hotspots of atypical size and shape. / Doctor of Philosophy / The focus of this work is called “spatial epidemiology”, which combines geography with public health, to answer the where, and why, of disease. This is a growing field, and you’ve likely seen it in the news and media. Have you ever seen a map of the United States turning red in some virus disaster movie? The real thing looks a lot like that. After the Ebola outbreak of 2014, public health agencies wanted to know where the next one might hit. Now that there is another outbreak, we need to ask where and how will it spread? What areas are hardest hit, and how bad is it going to get? We can answer all these questions with spatial epidemiology. Our work adds to two aspects of spatial epidemiology: niche modeling, and mobility. We use niche modeling to determine where we could find certain diseases, usually those that are spread by insects or animals. Consider Lyme disease, you get it from the bite of a tick, and the tick gets it from a white-footed mouse. But both the mice and ticks only live in certain parts of the country. With niche modeling we can determine where those are, and we can also guess at what makes those areas attractive to the mice and ticks. Is it winter harshness, summer temperatures, rainfall, and/or elevation? Is it something else? In Chapter 2, we show that you can extend this idea. Instead of just looking at where the disease is, what if we could guess how many people will get infected? What if we could do so, a year in advance? We show that this can be done, but we need a good idea of what the weather will be like next year. In Chapter 4, we show that you can do the same thing with hepatitis C. Instead of Lyme’s ticks and mice, hepatitis C depends on drug-use, unregulated tattooing, and unsafe sex. And like with Lyme, these things are only found in certain places. Instead of temperature or rainfall, we now need to find areas with drug-problems and poverty. But we can get an idea of this from the Census Bureau, and we can make a map of hepatitis C as easily as we did for Lyme. But hepatitis C spreads person-to-person. So, we need some idea of how people move around the area. This is where mobility comes in. Mobility is important for most public health work, from detecting outbreaks to estimating where the disease will spread next. In Chapter 3, we show how one could create a mobility model for a rural area where few maps exist. We also show how to use that model to guess where the next cases of Ebola will show up. In Chapter 4, we show how you could use mobility to improve outbreak and hotspot detection. We also show how it’s used to help estimate the number of cases in an area. Because that number depends on how many cases are imported from the surrounding areas. And the only way to estimate that is with mobility.
|
Page generated in 0.0765 seconds