Slow waves in un modello di crescita tumorale

In questo elaborato ho analizzato un sistema di reazione-diffusione proposto come modello per descrivere un fenomeno di crescita tumorale. In particolare, è stato approfondito il processo in cui l'invasione neoplastica è originata dalla produzione di un eccesso di ioni acidi da parte delle cellule maligne. Il sistema preso in esame descrive l'andamento di tre grandezze: la concentrazione di tessuto sano, la concentrazione di tessuto maligno e l'eccesso di ioni acidi. Ho quindi cercato soluzioni compatibili con il sistema le quali fossero funzioni della tipologia travelling waves, ossia onde che si propagano lungo l'asse reale con un grafico fissato e ad una velocità costante. I risultati ottenuti in questo lavoro sono stati così suddivisi: nel Capitolo 1 viene descritto il processo di invasione tumorale dal punto di vista biologico, nel Capitolo 2 vengono forniti alcuni lemmi e proposizioni preliminari, nel Capitolo 3 viene calcolata un'approssimazione della soluzione del sistema tramite onde del tipo slow waves e infine nel Capitolo 4 sono state studiate la presenza e la larghezza dello spazio interstiziale, ossia di una regione situata tra il tessuto sano e quello neoplastico nella quale si registra una concentrazione di cellule, sia normali sia maligne, praticamente nulla. Infine, sono state rappresentate graficamente le soluzioni in tre possibili situazioni caratterizzate da un diverso parametro di aggressività del tumore.

Slow passage through thresholds in quantum dot lasers

A turn on of a quantum dot (QD) semiconductor laser simultaneously operating at the ground state (GS) and excited state (ES) is investigated both experimentally and theoretically. We find experimentally that the slow passage through the two successive laser thresholds may lead to significant delays in the GS and ES turn ons. The difference between the turn-on times is measured as a function of the pump rate of change and reveals no clear power law. This has motivated a detailed analysis of rate equations appropriate for two-state lasing QD lasers. We find that the effective time of the GS turn on follows an -1/2 power law provided that the rate of change is not too small. The effective time of the ES transition follows an -1 power law, but its first order correction in ln is numerically significant. The two turn ons result from different physical mechanisms. The delay of the GS transition strongly depends on the slow growth of the dot population, whereas the ES transition only depends on the time needed to leave a repellent steady state.

Production et articulation des appartenances au mouvement Slow Fashion sur Twitter

Ce mémoire explore les productions et les articulations des appartenances au mouvement Slow Fashion sur Twitter. En réaction au modèle actuel prédominant du Fast Fashion, basé sur une surproduction et une surconsommation des vêtements, le Slow Fashion sensibilise les différents acteurs du secteur de la mode à avoir une vision plus consciente des impacts de leurs pratiques sur les travailleurs, les communautés et les écosystèmes (Fletcher, 2007) et propose une décélération des cycles de production et de consommation des vêtements. L’enjeu de cette recherche est de montrer que le Slow Fashion se dessine notamment à travers les relations entres les différents acteurs sur Twitter et que l'ensemble de ces interactions prend la forme d'un rhizome, c’est-à-dire d’un système dans lequel les éléments qui le composent ne suivent aucune arborescence, aucune hiérarchie et n’émanent pas d’un seul point d’origine. (Deleuze & Guattari, 1976) Sur Twitter, les appartenances au Slow Fashion font surface, se connectent les unes aux autres par des liens de nature différente. Consommateurs, designers, entreprises, journalistes, etc., ces parties prenantes construisent collectivement le Slow Fashion comme mouvement alternatif à la mode mainstream actuelle. Mon cadre théorique s’est construit grâce à une analyse de la littérature des concepts de mode, d’identité et d’appartenance afin de mieux appréhender le contexte dans lequel le mouvement a émergé. Puis, j’ai également réalisé une étude exploratoire netnographique sur Twitter au cours de laquelle j’ai observé, tout en y participant, les interactions sur la plateforme abordant le Slow Fashion et/ou la mode éthique. Publiée sur ce blogue (http://belongingtoslowfashion.blogspot.ca), cette « creative presentation of research » (Chapman & Sawchuk, 2012) ne constitue pas une histoire présentant les prétendues origines de ce mouvement mais plutôt une photographie partielle à un certain moment du Slow Fashion. Construite tel un rhizome, elle n’a ni début, ni fin, ni hiérarchie. J’invite alors les lectrices/lecteurs à choisir n’importe quelle entrée et à délaisser toute logique linéaire et déductive. Cette exploration sera guidée par des liens hypertextes ou des annotations qui tisseront des connexions avec d’autres parties ou feront émerger d’autres questionnements. Il s’agit d’offrir une introduction aux enjeux que pose le Slow Fashion, d’ouvrir la voie à d’autres recherches et d’autres réflexions, ou encore de sensibiliser sur ce sujet.

Sic transit – la socialité itinérante des centres commerciaux

C’est en supposant l’existence de la richesse interactionnelle des espaces publics que nous analysons, dans cet article, les flux de circulation contemporains des centres commerciaux comme étant l’expression d’une certaine socialité. Bien loin d’être un phénomène propre d’une foule amorphe ou un simple procédé de déplacements individuels, ces marches montrent un besoin de grégarité assumant une forme nomade ou itinérante. Nous soutenons que les centres commerciaux rendent actuels une structure anthropologique faisant de l’agrégation autour de l’espace une base pour la socialité. Ce qui distingue la socialité itinérante est la traversée de l’espace et de la matérialité physique dans le seul but de la transcender. Bien plus que simplement consommer ou se déplacer fonctionnellement, ces flux semblent répondre à l’exigence, face à une austérité urbaine, des formes communautaires du lien social.

Motivating the use of public transit through a mobile glanceable display

With increasing concerns about the impact of global warming on human life, policy makers around the world and researchers have sought for technological solutions that have the potential to attenuate this process. This thesis describes the design and evaluation of an information appliance that aims to increase the use of public transportation. We developed a mobile glanceable display that, being aware of the user’s transportation routines, provides awareness cues about bus arrival time, grounded upon the vision of Ambient Intelligence. We present the design process we followed, from ideation to building a prototype and conducting a field study, and conclude with a set of guidelines for the design of relevant personal information systems. More specifically we seek to test the following hypotheses: 1) That the tangible prototype that provides ambient cues will be used more frequently than a similar purpose mobile app, 2) That the tangible prototype will reduce the waiting time at the bus stop, 3) That the tangible prototype will result to reduced anxiety on passengers, 4) That the tangible prototype will result to an increase in the perceived reliability of the transit service, 5) That the tangible prototype will enhance users’ efficiency in reading the bus schedules and 6) That the tangible prototype will make individuals more likely to use public transit. In a field study, we compare the tangible prototype against the mobile app and a control condition where participants were given no external support in obtaining bus arrival information, other than their existing routines. Using qualitative and quantitative data, we test the aforementioned hypotheses and explore users’ reactions to the prototype we developed.

The development of an algorithm to track blood pressure accurately based on the pulse transit time method

Oscillometric blood pressure (BP) monitors are currently used to diagnose hypertension both in home and clinical settings. These monitors take BP measurements once every 15 minutes over a 24 hour period and provide a reliable and accurate system that is minimally invasive. Although intermittent cuff measurements have proven to be a good indicator of BP, a continuous BP monitor is highly desirable for the diagnosis of hypertension and other cardiac diseases. However, no such devices currently exist. A novel algorithm has been developed based on the Pulse Transit Time (PTT) method, which would allow non-invasive and continuous BP measurement. PTT is defined as the time it takes the BP wave to propagate from the heart to a specified point on the body. After an initial BP measurement, PTT algorithms can track BP over short periods of time, known as calibration intervals. After this time has elapsed, a new BP measurement is required to recalibrate the algorithm. Using the PhysioNet database as a basis, the new algorithm was developed and tested using 15 patients, each tested 3 times over a period of 30 minutes. The predicted BP of the algorithm was compared to the arterial BP of each patient. It has been established that this new algorithm is capable of tracking BP over 12 minutes without the need for recalibration, using the BHS standard, a 100% improvement over what has been previously identified. The algorithm was incorporated into a new system based on its requirements and was tested using three volunteers. The results mirrored those previously observed, providing accurate BP measurements when a 12 minute calibration interval was used. This new system provides a significant improvement to the existing method allowing BP to be monitored continuously and non-invasively, on a beat-to-beat basis over 24 hours, adding major clinical and diagnostic value.

Sic transit – la socialité itinérante des centres commerciaux

C’est en supposant l’existence de la richesse interactionnelle des espaces publics que nous analysons, dans cet article, les flux de circulation contemporains des centres commerciaux comme étant l’expression d’une certaine socialité. Bien loin d’être un phénomène propre d’une foule amorphe ou un simple procédé de déplacements individuels, ces marches montrent un besoin de grégarité assumant une forme nomade ou itinérante. Nous soutenons que les centres commerciaux rendent actuels une structure anthropologique faisant de l’agrégation autour de l’espace une base pour la socialité. Ce qui distingue la socialité itinérante est la traversée de l’espace et de la matérialité physique dans le seul but de la transcender. Bien plus que simplement consommer ou se déplacer fonctionnellement, ces flux semblent répondre à l’exigence, face à une austérité urbaine, des formes communautaires du lien social.

Motivating the use of public transit through a mobile glanceable display

With increasing concerns about the impact of global warming on human life, policy makers around the world and researchers have sought for technological solutions that have the potential to attenuate this process. This thesis describes the design and evaluation of an information appliance that aims to increase the use of public transportation. We developed a mobile glanceable display that, being aware of the user’s transportation routines, provides awareness cues about bus arrival time, grounded upon the vision of Ambient Intelligence. We present the design process we followed, from ideation to building a prototype and conducting a field study, and conclude with a set of guidelines for the design of relevant personal information systems. More specifically we seek to test the following hypotheses: 1) That the tangible prototype that provides ambient cues will be used more frequently than a similar purpose mobile app, 2) That the tangible prototype will reduce the waiting time at the bus stop, 3) That the tangible prototype will result to reduced anxiety on passengers, 4) That the tangible prototype will result to an increase in the perceived reliability of the transit service, 5) That the tangible prototype will enhance users’ efficiency in reading the bus schedules and 6) That the tangible prototype will make individuals more likely to use public transit. In a field study, we compare the tangible prototype against the mobile app and a control condition where participants were given no external support in obtaining bus arrival information, other than their existing routines. Using qualitative and quantitative data, we test the aforementioned hypotheses and explore users’ reactions to the prototype we developed.

Diverticulosis y relación con el consumo de fibra en pacientes del Hospital Universitario de la Samaritana

Introducción: La diverticulosis es la condición más frecuentemente encontrada en la colonoscopia, condición asintomática, con un alto costo para el sistema de salud. Diversos factores han demostrado estar en relación con la aparición de la enfermedad. En nuestra población, esta información se desconoce; el objetivo del estudio es la caracterización de la población con diverticulosis y su relación con la frecuencia de la ingesta de fibra. Materiales y Métodos: Estudio observacional prospectivo de corte transversal con componente analítico. Realizado a todas las personas que asistieron al HUS a realización de colonoscopia entre Noviembre de 2015 y Abril de 2016. Se recolectaron datos de la frecuencia de fibra ingerida a través de entrevistas basadas. Resultados: Se estudiaron 278 personas, 55.7% mujeres. La prevalencia de diverticulosis fue de 21.58%, siendo más frecuente en mujeres ( 66,7%), 31% entre los 71-80 años, 2,16% tenían antecedente familiar de diverticulosis; principal sitio de afectación fue colon sigmoide en las mujeres y el colon descendente en los hombres. En las personas con diverticulosis el consumo de harina de trigo fue mayor (91,67% vs 86,7%), mientras el consumo de frutas fue mayor en las personas que no presentaron diverticulosis (83,49% vs 78,33%). Conclusiones: La prevalencia de diverticulosis es similar a lo reportado en la literatura. Así mismo se encontró un mayor consumo de fibra en la población sin divertículos lo que hace pensar que a pesar de que esta condición es multifactorial , el consumo de mayores cantidades de fibra puede prevenir la aparición de la misma

Soil amendment and slow release fertilizer preparation from castor meal.

2008

Green nanocomposites as carriers for slow-release of tebuconazole.

2016

Near-infrared spectroscopic study of basic aluminum sulfate and nitrate

The tridecameric Al-polymer [AlO4Al12(OH)24(H2O)12]7+ was prepared by forced hydrolysis of Al3+ up to an OH/Al molar ratio of 2.2. Under slow evaporation crystals were formed of Al13-nitrate. Upon addition of sulfate the tridecamer crystallised as the monoclinic Al13-sulfate. These crystals have been studied using near-infrared spectroscopy and compared to Al2(SO4)3.16H2O. Although the near-infrared spectra of the Al13-sulfate and nitrate are very similar indicating similar crystal structures, there are minor differences related to the strength with which the crystal water molecules are bonded to the salt groups. The interaction between crystal water and nitrate is stronger than with the sulfate as reflected by the shift of the crystal water band positions from 6213, 4874 and 4553 cm–1 for the Al13 sulfate towards 5925, 4848 and 4532 cm–1 for the nitrate. A reversed shift from 5079 and 5037 cm–1 for the sulfate towards 5238 and 5040 cm–1 for the nitrate for the water molecules in the Al13 indicate that the nitrate-Al13 bond is weakened due to the influence of the crystal water on the nitrate. The Al-OH bond in the Al13 complex is not influenced by changing the salt group due to the shielding by the water molecules of the Al13 complex.