2,713 research outputs found
Evolutionary ecology of host-symbiont interactions
Imperial Users onl
Long Term Evolution of the Size Distribution of Portuguese Cities
In this paper we study the evolution of the Portuguese urban system from 1864 to 2001. We apply the rank-size model and use rank-size estimates to describe the evolution of city-size hierarchy. Non paretian behaviour of the distribution is examined by adding a quadratic term to the basic equation of the model. Our results enhance two different processes in the evolution of urban system: until the middle of the twentieth century urban growth was accompanied by population concentration in the largest cities and proliferation of small cities; afterwards growth benefits middle size cities, reinforced in the last decades by heavy population losses in the two largest cities. From the association between the characteristics and evolving pattern of city size distribution and the spatial pattern of urban growth, it appears that the non paretian behaviour of city size distribution in the last decades can be linked to the particular growth process of cities located in the proximity of the central cities of the two metropolitan areas of Portugalâs mainland. In order to obtain a better understanding of the dynamics of the Portuguese urban system we examine the movements in the ranking of cities. We also analyse the existence of spatial correlation in the process of urban hierarchy restructuring.
The evolution of city size distribution in Portugal: 1864-2001
The rank-size model - which states that the size distribution of cities in a country follows a Pareto distribution - has been recognized as one of those stylised facts or amazing empirical regularities, in spatial economics. A common problem in city size distribution studies concerns the definition of âcitiesâ, namely the consistency of those definitions over time. In this paper we use a city-proper data base which uses a consistent definition of cities from 1864 to 1991. Portugal is a country with long established national borders and whose mainland urban system shows a constant number of cities over that period. In Portugal, empirical evidence on city size distribution based on census data shows that two large cities dominate the urban system, associated with a large number of very small cities and a clear deficit of medium-size cities. In this paper we analyse the evolution of the rank size exponent and examine the effect of varying city size cut-offs on the estimated value of that exponent. Then, we study the deviations of the rank-size distribution from linearity. Finally, we explore the dynamics underlying the evolution of the urban system by examining the relationship between city growth rates and city size. Keywords: city size distribution, Zipfâs law, rank-size, urban hierarchy, urban primacy
The evolution of city size distribution in Portugal: 1864-2001
The rank-size model - which states that the size distribution of cities in a country follows a Pareto distribution - has been recognized as one of those stylized facts or amazing empirical regularities, in spatial economics. A common problem in city size distribution studies concerns the definition of âcitiesâ, namely the consistency of those definitions over time. In this paper we use a city-proper data base which uses a consistent definition of cities from 1864 to 1991. Portugal is a country with long established national borders and whose mainland urban system shows a constant number of cities over that period. In Portugal, empirical evidence on city size distribution based on census data shows that two large cities dominate the urban system, associated with a large number of very small cities and a clear deficit of medium-size cities. In this paper we analyse the evolution of the rank size exponent and examine the effect of varying city size cut-offs on the estimate value of that exponent. Then, we study the deviations of the rank-size distribution from linearity. Finally, we explore the dynamics underlying the evolution of the urban system by examining the relationship between city growth rates and city size.city size distribution, Zipfâs law, urban hierarchy, urban primacy
Long term evolution of the size distribution of Portuguese cities
In this paper we study the evolution of the Portuguese urban system from 1864 to 2001. We apply the rank-size model and use rank-size estimates to describe the evolution of city-size hierarchy. NonParetian behavior of the distribution is examined by adding a quadratic term to the basic equation of the model. Our results enhance two different processes in the evolution of urban system: until the middle of the twentieth century urban growth was accompanied by population concentration in the largest cities; afterwards growth benefits middle size cities, reinforced in the last decades by heavy population losses in the two largest cities. From the association between the characteristics and evolving pattern of city size distribution and the spatial pattern of urban growth, it appears that the nonParetian behavior of city size distribution in the last decades can be linked to the particular growth process of cities located in the proximity of the central cities of the two metropolitan areas of mainland Portugal. In order to obtain a better understanding of the dynamics of the Portuguese urban system we examine the movements in the ranking of cities, through a Markov chain process. We also analyse the existence of spatial correlation in the process of urban hierarchy restructuring.Urban hierarchy, rank-size distribution, urban growth, Markov processes
Antibacterial scaffolds constituted by trilayers of microfibers based on polylactide and poly (3-hydroxybutyrate-co-3-hydroxyvalerate)
Lâobjectiu dâaquest treball final de mĂ ster va ser la fabricaciĂł de fibres poroses uniaxials i amb
tricapa que presentĂ©sfuncions antibacterianesi potencialment dâaltresfuncionalitats (antitumoral,
antioxidant, antibaterial...). Les fibres es van fabricar mitjançant la tĂšcnica de lâelectrospinning a
partir dâuna dissoluciĂł de polĂmers i sempre treballant amb un polĂmer comercial, el PHB. El disseny
de les matrius va consistir en una capa de mescla PLA/PEG als extrems i PHBV al mig, amb
configuració similar a un tipus sandvitx. La droga antibacterial es va incorporar també a la capa
intermitja, mesclada amb el PHBV. A mĂ©s, van afegir tambĂ© partĂcules dâhidroxiapatita per formar
complexes Matriu-Hidroxiapatita i aixĂ poder estudiar la alliberaciĂł de droga.
Per tal dâobtenir les matrius amb les condicions ĂČptimes, es van modificar els parĂ metres durant
lâelectrospinning de fibres amb una sola capa i es van provar diferents concentracions i diferents
dissolvents. Un cop obtinguts els valors ĂČptims dels parĂ metres i el dissolvent adequat, es va
procedir a crear diferent matrius amb diferents caracterĂstiques i components per el seu posterior
estudi. En el desenvolupament del projecte es van dur a terme diferents caracteritzacions, tant
fĂsiques com quĂmiques de les matrius creades.
Primer es va estudiar els angles de contacte, en funciĂł del comportament de lâaigua al estar en
contacte amb la superfĂcie de les matrius. Tots els resultats obtinguts van ser superiors a 120Âș per
tant, es va considerar el polĂmer estudiat era de tipus hidrofĂČbic, ja que presentava valors superiors
al 90Âș. Posteriorment, es van analitzar els diĂ metres de les fibres que sâobtenien a les matrius
mitjançant microscĂČpia electrĂČnica de rastreig (SEM) i tambĂ© es va obtenir lâespectre de cadascuna
dels components que es van utilitzar per muntar les matrius (per espectroscĂČpia infraroig) per tal
dâobtenir les absorcions dels components que formaven part dâelles.
Per Ășltim es va realitzar un estudi de lâalliberaciĂł de la droga, dissolent una mostra de les matrius
que contenien la droga (per triplicat) amb un medi utilitzat per creixement biolĂČgic (PBS). Lâestudi
es va realitzar en un temps total de 48h, realitzant mostreigs periĂČdics i finalment, analitzant les
absorbĂ ncies obtingudes mitjançant lâespectrometria UV-Vis per obtenir concentracions finals i
amb les seves regressions, obtenir dades sobre lâalliberaciĂł en el temps de la droga.
El treball realitzat al laboratori inclou el muntatge experimental, la preparaciĂł de les dissolucions
de polĂmers per dur a terme cadascuna de les tĂšcniquesi la realitzaciĂł dels experiments mitjançant
cadascuna de les tĂšcniques mencionades. Finalment, a partir de les diferents proves realitzades es
va poder determinar la naturalesa del polĂmer emprat, la seva morfologia, el seu comportament
quĂmic aixĂ com la capacitat dâalliberament de droga que presenta vers el temps.El objetivo de este trabajo final de mĂĄster fue la fabricaciĂłn de fibras porosas uniaxiales y con
tricapa que presentase funciones antibacterianas y potencialmente otras funcionalidades
(antitumoral, antioxidante, antibacterianas...). Las fibras se fabricaron mediante la técnica de la
electrospinning a partir de una disoluciĂłn de polĂmeros y siempre trabajando con un polĂmero
comercial, el PHB. El diseño de las matrices consistió en una capa de mezcla PLA/PEG en los
extremos y PHBV en medio, con configuraciĂłn similar a un tipo sĂĄndwich. La droga antibacteriana
se incorporó también a la capa intermedia, mezclada con el PHBV. Ademås, se añadieron también
partĂculas de hidroxiapatita para formar complejos Matriz-Hidroxiapatita y asĂ poder estudiar la
liberaciĂłn de droga.
Para obtener las matrices con las condiciones Ăłptimas, se modificaron los parĂĄmetros durante el
electrospinning de fibras con una sola capa y se probaron diferentes concentraciones y diferentes
disolventes. Una vez obtenidos los valores Ăłptimos de los parĂĄmetros y el disolvente adecuado, se
procediĂł a crear diferentes matrices con diferentes caracterĂsticas y componentes para su posterior
estudio. En el desarrollo del proyecto se llevaron a cabo diferentes caracterizaciones, tanto fĂsicas
como quĂmicas de las matrices creadas.
Primero se estudiĂł los ĂĄngulos de contacto, en funciĂłn del comportamiento del agua al estar en
contacto con la superficie de las matrices. Todos los resultados obtenidos fueron superiores a 120°
por lo tanto, se considerĂł que el polĂmero estudiado era de tipo hidrofĂłbico, puesto que presentaba
valores superiores al 90°. Posteriormente, se analizaron los diĂĄmetros de las fibras que se obtenĂan
mediante microscopia electrónica de rastreo (SEM) y también se obtuvo el espectro de cada uno
de los componentes que se utilizaron para montar las matrices (por espectroscopia infrarrojo) para
obtener las absorciones de los componentes que formaban parte de ellas.
Por Ășltimo, se realizĂł un estudio de la liberaciĂłn de la droga, disolviendo una muestra de las
matrices que contenĂan la droga (por triplicado) con un medio utilizado para crecimiento biolĂłgico
(PBS). El estudio se realizĂł durante un tiempo total de 48h, realizando muestreos periĂłdicos y
finalmente, analizando las absorbancias obtenidas mediante la espectrometrĂa UV-Vis, para
obtener concentraciones finales y con susregresiones, obtener datos sobre la liberaciĂłn de la droga
en el tiempo.
El trabajo realizado en el laboratorio incluye el montaje experimental, la preparaciĂłn de las
disoluciones de polĂmeros para llevar a cabo cada una de las tĂ©cnicas y la realizaciĂłn de los
experimentos mediante cada una de las técnicas mencionadas. Finalmente, a partir de las
diferentes pruebas realizadas se pudo determinar la naturaleza del polĂmero empleado, su
morfologĂa, su comportamiento quĂmico, asĂ como la capacidad de liberaciĂłn de droga presentaba
respecto al tiempo.The objective of this final master thesis was the fabrication of porous uniaxial trilayer fibers that
present antibacterial functions and other potential functionalities (antitumoral, antioxidant,
antibacterial...). Fibers were made by means of electrospinning technique, from a polymer solution
and aways working with a commercial polymer type, PHB. Scaffolds design consists of a mixture
PLA/PEG applied in a layer on extremes and PHBV at the middle, with a sandwich seems
configuration. Antibacterial drug was added to intermediate layer, mixed with PHBV. Additionally,
it was added particles of hydroxyapatite to form Scaffold-Hydroxyapatite complexes and allow to
study drug liberation.
To obtain scaffolds in optimum conditions, it was modified the parameters during electrospinning
process with unilayer scaffolds and there were tested different concentrations and solvents. Once
optimal parameters were obtained and the suitable solvent, different scaffolds were created with
different characteristics and components for its posterior study. During the development of the
project, different physical and chemical characterizations were made on the created polymer
scaffolds.
Firstly, contact angle of the scaffolds was evaluated in function of water behavior been in contact
with surface scaffold. All angles obtained were higher than 120Âș and, for so, it was considered that
the polymer analyzed was hydrophobic, as it has values higher than 90Âș. Subsequently, it was
analyzed the diameters of fibers by means ofscanning electron microscopy (SEM) and spectra were
obtained for each of the components that were used to make the scaffolds (by FTIR spectroscopy)
and obtain the absorbances of the components that be part of them.
Finally, it was made a liberation of the drug study, dissolving a sample of the scaffold that contains
the drug per triplicated, with a biological grown media (PBS). The study was done during a total
time of 48h, making periodical samplings and, finally, analyzing obtained absorbances by means of
UV-Vis spectroscopy, to obtain the final concentrations and its regressions, obtaining data about
drug release pending time.
The laboratory tasks made, include experimental setup, preparation of polymer solutions to carry
out each of the techniques and the perform of the experiments by means of all the mentioned
techniques.
Finally, from the different tests performed, it was possible to stablish the nature of the polymer
used, its morphology, chemical behavior, and its capacity to drug release in time
Diseño del proceso de elaboración
El presente trabajo trata sobre el diseño del proceso para la elaboraciĂłn de un subproducto que permita diversificar la producciĂłn de banano deshidratado, cumpliendo con los estĂĄndares de calidad exigidos. Para ello se aprovecharon los desperdicios propios de la lĂnea, con el fin de obtener un producto uniforme, de calidad y precio competitivo.
Se propusieron diferentes productos para ser desarrollados, y se eligió aquel se adaptaba de una mejor manera a los requerimientos establecidos. Luego de elegir las materias primas adecuadas, se diseñó el proceso de elaboración del producto y se establecieron métodos para el control del peso por unidad.
Por otro lado, se determinaron los parĂĄmetros fĂsicos, tales como peso y tamaño por unidad, y se establecieron las caracterĂsticas organolĂ©pticas, microbiolĂłgicas y nutricionales del producto. Finalmente, se determinĂł la vida Ăștil del producto obtenido a diferentes temperaturas
"Pan precocido suave con especies"
During the past years, peopleâs life styles have been changing due to the new
trends adopted around the world.
Nowadays, people live faster and dedicated more time to work and the families are
smaller.
The Ecuadorians are adopting this XXI lifestyle and this provokes the consuming
habits change, and in a specific way the feeding habits.
The traditional elaboration of meals in the kitchen that requires of long time and
dedication has left behind. For that reason, food markets require of nutritious
products of quick preparation and ready to be consumed.
The present Project consist in the development of a product designed for a market
as the one mentioned before, in which details its technical development,
formulation, manufacturing, sensing test and quality control .
The project also includes the market research realized before the development of
the product. The marketplace is focused in Quitoâs high class institutional market.
In addition, the financial study and the legal aspect are also shown in this project.Durante los Ășltimos años la forma de vida de las personas ha ido cambiando
debido a las nuevas tendencias que se adoptan en el mundo.
Hoy en dĂa se vive mĂĄs rĂĄpido y cada vez se le dedica mĂĄs tiempo al trabajo;
ademås las familias son cada vez mås pequeñas.
Los ecuatorianos poco a poco van adoptando este tipo de vida del siglo XXI y esto
provoca que los hĂĄbitos de consumo vayan cambiando, y el consumo de los
alimentos especĂficamente.
La elaboraciĂłn tradicional de los alimentos en la cocina, que requiere de largos
tiempos y dedicaciĂłn, ha ido quedando atrĂĄs. Por lo tanto los nuevos mercados
requieren de productos alimenticios de fåcil y råpida preparación y que estén
listos para consumir.
El presente proyecto consiste en el desarrollo de un producto diseñado para un
mercado como el mencionado, en el cual se detalla su desarrollo técnico:
formulaciĂłn, manufactura, pruebas sensoriales y control de calidad.
El proyecto también incluye el estudio de mercado realizado previo al desarrollo
del producto, que se enfoca en el mercado institucional de clase alta de la ciudad
de Quito. AdemĂĄs se incluye un estudio financiero y los aspectos legales que
envuelven el desarrollo del proyecto
MĂșsica e inspiração em The Lady Vanishes de Alfred Hitchcock
Tendo como base The Lady Vanishes (1938), o presente ensaio trata o conceito de conspiração no filme em causa e noutros do mesmo realizador, relacionando-o com a importĂąncia tambĂ©m da mĂșsica em Alfred Hitchcock, ao mesmo tempo que se demonstra o carĂĄcter revolucionĂĄrio da sua obra. No thriller, enquanto gĂ©nero inaugurado por Hitchcock, a conspiração figura como um pano de fundo da intriga que nĂŁo chega, afinal, a ser nada em concreto. A mĂșsica deixa de ser apenas coadjuvante das imagens para, refletindo sobre elas, deter um papel decisivo nos filmes deste cineasta. As tĂ©cnicas da conspiração no plano estĂ©tico sĂŁo ainda comparadas Ă s do plano sociolĂłgico, aqui ilustradas pelas tĂ©cnicas efetivas da ideologia do Nacional Socialismo, de alguma forma perscrutadas por Hitchcock jĂĄ em 1938.Based on The Lady Vanishes (1938), this paper covers the concept of conspiracy in that movie and in others of the same director, comparing it with the importance of music in Alfred Hitchcock and showing at the same time the revolutionary features of his work. In the thriller, film genre initiated by Hitchcock, conspiracy figures as a background of the plot, but it isnât, actually, nothing in concrete. Music is no longer a mere support for images but it reflects about them, playing a crucial role in this filmmakerâs movies. The conspiracy techniques in the aesthetic field are also compared with the effective techniques in the sociologic field, here illustrated by the National Socialismâs ideology, which techniques were somehow foreseen by Hitchcock in 1938.info:eu-repo/semantics/publishedVersio
Aragons "La Mise Ă mort" und die Rezeption romantischer Motive
"La Mise Ă mort" gehört der dritten Schaffensperiode Louis Aragons an. Sie folgt der surrealistischen Phase und der "wirklichen Welt"- Periode nach. Dieser Roman aus dem Jahr 1965 ist die Bilanz seines bisherigen Werkes. Aragon konzentriert sich auf Probleme seines Schaffens und entwirft eine Synthese seiner eigenen Entwicklung in fiktiver Gestalt. Er greift dabei auf die Hegelsche Dialektik zurĂŒck, die er in seiner Jugend intensiv studiert hat. Die WidersprĂŒchlichkeit seiner Entwicklung stellt er in La Mise Ă mort durch die DoppelgĂ€nger Alfred (der ErzĂ€hler des Romans) und Anthoine (Autor der "Drei ErzĂ€hlungen aus der roten Mappe"), und auch Christian, einen dritten DoppelgĂ€nger, dar. Das Grundthema des Romans ist die Suche nach der Wahrheit auf drei Ebenen: Nach der historischen Wahrheit in "Murmure", nach der Wahrheit des einzelnen Menschen in "Le Carnaval" und nach der Wahrheit in der Kunst in "Oedipe". Die drei ErzĂ€hlungen aus der roten Mappe bringen die Vergangenheit Aragons ans Licht. Die Wiederentdeckung der surrealistischen Vergangenheit ist die Hauptantriebskraft fĂŒr das Schreiben der drei ErzĂ€hlungen. Das surrealistische Erbe muss dabei im Kontext der Romantik-Rezeption betrachtet werden (vor allem der deutschen Romantik). Von besonderer Brisanz fĂŒr die Realismusdiskussion in La Mise Ă mort ist die Rezeption der im Roman behandelten romantischen Motive des Spiegels, des Schattens und des DoppelgĂ€ngers. Sie tragen zu einer Ăffnung des sozialistischen Realismusbegriffs bei, indem sie Werte der Phantasie und der SubjektivitĂ€t darstellen und damit die Freiheit in der Wahl der Gestaltungsmethode erweitern."La Mise Ă mort" belongs to the third phase of Louis Aragon's literary creation after the Surrealist period and the "Monde rĂ©el" phase; this 1965 novel appears as a balance of his work. Aragon concentrates on the problems of his creative work and sketches a synthesis of its evolution in fictional form using the philosophical method that he had studied in his youth and applied in his early writings: the Hegelian dialectic. It is through the personae of Alfred, narrator of the novel, Anthoine, author of the "Trois contes de la chemise rouge", and also Christian, that he presents the contradictions of this evolution. The main theme chosen for this presentation is the search for truth, trying to show the complexity of the various aspects of reality: the search for historical truth in "Murmure"; the search for individual truth in "Le Carnaval"; and the search for truth in art in "Oedipe". The rediscovery of the surrealist past is the main driving force behind the writing of the three stories, and the surrealist heritage appears in the context of the reception of Romanticism, especially German Romanticism. Particularly important for the reception of German Romanticism will be the three motifs of the mirror, the shadow, and the double (DoppelgĂ€nger), illustrating a broad conception of socialist realism at this stage, distancing itself from dogmatic conceptions of realism and extending the concept to values of fantasy and subjectivity
- âŠ