Academic literature on the topic 'Continuum de soin'

Médecin Sans Frontière (MSF) intervient depuis les années 1980 à Ndhiwa, un sous-comté du Sud-Ouest du Kenya, où sévit une épidémie généralisée de VIH, avec une prévalence à 24% et une incidence à 2,2/100 personnes année (PA). Conformément aux objectifs de l’ONUSIDA 90-90-90, puis 95-95-95, MSF a décidé de mettre en place différentes interventions pour diminuer l’incidence de l’infection par le VIH. Dans un premier temps, nous avons développé un modèle mathématique de la transmission et de l’histoire naturelle de l’infection par le VIH à Ndhiwa afin d’étudier l’efficacité et le coût efficacité de trois niveaux d’interventions sur le continuum de soin. Nous avons ainsi estimé qu’en maintenant l’offre de soins à son niveau actuel, sans intervention, l’incidence de l’infection par le VIH diminuerait à 1,51/100 PA en 2032, tandis que seules les interventions de rétention et la combinaison de toutes les stratégies faisaient baisser l’incidence respectivement à 1,03/100 PA et 0,75/100 PA. Comparé au standard de soins, la stratégie de rétention avait un rapport incrémental de coût-efficacité de 130€/année de vie gagnée (AVG) tandis que La combinaison des interventions atteint un ICER de 370€/AVG. Dans un deuxième temps, nous avons modélisé l’efficacité d’une intervention qui améliorerait le continuum de soin de 90-90-90 à 95-95-95, comparée à une intervention qui implémenterait une prophylaxie pré-exposition (PrEP) sur une population à haut risque avec un taux de couverture de 10%. Nous estimons que dans une épidémie généralisée où le continuum de soin atteint 90-90-90, l’amélioration du continuum de soin à 95-95-95 est plus efficace que la PrEP pour diminuer l’incidence de l’infection par le VIH En conclusion, les résultats de notre travail soulignent les effets synergiques e très coût-efficace d’interventions multimodales sur le continuum de soin, et leur rôle important aussi important que la PrEP pour diminuer l’incidence de l’infection par le VIH<br>Médecin Sans Frontière (MSF) have been working since the early 1980’s on HIV care delivery in Ndhiwa, a rural sub-county in Southwest Kenya. This area suffers from a generalized HIV epidemic, with 24% prevalence and 2.2/100 person years (PY) incidence. In line with the UNAIDS 90-90-90 and 95-95-95 targets, MSF has implemented interventions to decrease HIV incidence. In the first part of this work, we have developped a mathematical model of HIV natural history and transmission in Ndhiwa to evaluate the effectiveness and cost-effectiveness of three different interventions on HIV continuum of care. We estimated than current standard of care would decrease HIV incidence to 1.51/100 PY in 2032, whereas only retention intervention and combined interventions would further decrease HIV incidence to 1.03/100 PY and 0,75/100 PY, respectively. Compared to standard of care, retention to care intervention has an incremental cost-effectiveness ratio (ICER) of 130€/years of live saved (YLS) whereas combined intervention has an ICER of 370€/YLS. In the second part, we modeled the effectiveness of the improvement of continuum of care from 90-90-90 to 95-95-95, compared with a Pre-exposure Prophylaxis (PrEP) intervention with 10% coverage in high-risk group. We found that in the context of generalized epidemic where continuum of care reach 90-90-90, an improvement to 95-95-95 would be more effective than PrEP to decrease incidence. To conclude, combined interventions on HIV continuum of care have synergic effects and are very cost-effective. We also underlined the importance of maintaining a high level continuum of care to decrease HIV incidence, which is as important as PrEP to fight the HIV pandemic

Vascular plants comprise 20-30% lignin, constituting a considerable organic input to soils. Lignin is not necessarily preserved in soils, but the fate of its decomposition products in the wider environment is not well understood. Therefore, the overarching hypothesis tested herein was that a significant proportion of lignin is solubilised and lost from soils by transport in water. Solid phase extraction was used to extract lignin phenols from dissolved organic matter (DOM) from water outlets adjacent to major land use types (grazed grassland, deciduous woodland, and moorland) and compared to the lignin phenols from representative vegetation types, animal dungs and soils from each land use type. The phenols were identified and quantified using thermally assisted hydrolysis and methylation using tetramethylammonium hydroxide. Leachates from lysimeters treated with four vegetation types (grass, buttercup, ash, and oak) were sampled in a 22 month chronosequence, showing that some of the dominant phenols detected in the vegetation were also dominant in the respective DOM. A proportional relationship between increasing temperature and loss of representative lignin phenols in DOM was observed. Comparison of the dominant phenols in vegetation, soil and water sampled from field sites suggested specific lignin phenols could be used as biomarkers for different land uses. The concentrations of organic carbon-normalised total lignin phenols in the soils were similar to those in water, indicating that a considerable proportion of lignin in soils is lost via leaching. There was no significant difference in losses of lignin phenols between each land use type. Application of different rates of dissolved lignin to lysimeters indicated that the amount of water added was a dominant driver of transport through soil over 16 days, and that molecular structure also influenced transport rates of individual phenols. The impact of this research is that climate change (increased precipitation and warming) may significantly affect the loss of lignin by increased solubilisation and leaching from soils.

The Earth’s critical zone (ECZ) is the near-surface domain that regulates the availability of most life-sustaining resources. Among all the subdomains of the ECZ, a crucial role is played by the Soil-Plant continuum (SP), as it is a major performer of the exchanges of mass and energy between soil and plants (and then atmosphere). However, despite its importance and its strong interconnection with human activity, the characterization of this subdomain is still in an early stage, mainly because of the lack of spatial and temporal information regarding the occurring processes. To overcome this issue, we present the combination of geophysical measurements and hydrological modeling in the framework of a hydrogeophysical approach, with the aim of characterizing the active root zone, i.e. the portion of the root system involved in the water uptake. In fact, the water uptake is performed by root hair, the microscopic cell outgrowths whose location is difficult (if not impossible) also after the removal of the root system from the soil. Nevertheless, determining its position is fundamental not only for merely scientific purposes, but most of all for practical applications, as it affects the performing of precision irrigation. Therefore, in this work I propose the identification of the active root zone on the basis of its main effect, i.e. the reduction of soil water content over time. This is achieved by means of 3-D small-scale electrical resistivity tomography (ERT) carried out combining superficial and borehole electrodes. We monitored the processes occur-ring in the root zone of three orange trees located in south-eastern Sicily. These trees are drip irrigated according to different deficit irrigation techniques to improve the exploitation of the water resource, while the plants’ transpiration is monitored thanks to sap flow and eddy covariance measurements. More in detail, in the first case study ERT measurements before and after the cut of the tree are compared, while in the second case study the ERT monitoring is focused on two orange trees drip irrigated with different treatments (i.e. full irrigation and partial root drying). The datasets thus obtained provide interesting insights into the root system activity, given their abundance of information regarding both atmospheric and underground phenomena (i.e. transpiration and root water uptake, respectively). In particular, the ERT time-lapse approach well highlights the portions subject to a decrease in water content, which can be related to the water uptake put in place by the plants. Nevertheless, the interpretation of the resistivity patterns, although combined with agronomic information, can be rather intricate. A proper hydrological modeling provides a solution to this problem, even if choosing the most suitable approach requires a specific mathematical analysis. To do this, we developed a synthetic case study with two identical hydrological models, one of which describing also the activity of an orange tree. These models resemble the real datasets provided by the ERT measurements, without all the uncertainties introduced by the geophysical acquisition and the model calibration. The location of the active root zone is reconstructed from the combination of these two models by means of Taylor series expansion, with particular reference to the effects of the approximation thus introduced. The final aim is to evaluate the proposed numerical procedure for a future application on one of real case study presented in this work.<br>La Earth's critical zone (ECZ) rappresenta la porzione più esterna del pianeta Terra ed è sede di numerosi processi che regolano la disponibilità della maggior parte delle sostanze necessarie alla vita. Tra i vari sottodomini in cui essa può essere suddivisa, il continuum Suolo-Pianta (SP) svolge un ruolo cruciale, in quanto è uno dei maggiori regolatori degli scambi di massa ed energia tra suolo e piante (e quindi atmosfera). Nonostante la forte interconnessione con l'attività umana, la caratterizzazione del SP è ancora in una fase embrionale, principalmente legata alla mancanza di informazioni sia spaziali che temporali riguardo ai processi che lo caratterizzano. In questo lavoro presentiamo quindi una combinazione di tomografia di resistività elettrica (ERT) e modellazione idrologica secondo l'approccio idrogeofisico, con l'obiettivo di caratterizzare la "active root zone", ossia la porzione del sistema radicale coinvolta nel processo di assorbimento di acqua dal suolo. Più nel dettaglio, questo processo è messo in atto dai peli radicali, delle microscopiche estroflessioni la cui localizzazione è difficile (se non impossibile) anche in seguito alla rimozione del sistema radicale dal suolo. Ciononostante, la sua localizzazione è fondamentale soprattutto da un punto di vista agronomico, poiché necessaria per una corretta applicazione delle tecniche di irrigazione di precisione. In questo lavoro presento quindi due casi studio in cui l'active root zone è identificata sulla base del suo effetto principale, ossia la diminuzione di contenuto idrico del suolo. I casi studio presentati comprendono tre alberi d’arancio situati nel sud-est della Sicilia ed irrigati mediante diverse tecniche di microirrigazione (nota anche come "irrigazione a goccia"). In particolare, nel primo caso studio sono comparate misure ERT acquisite prima e dopo il taglio della pianta, mentre nel secondo caso studio il monitoraggio ERT è focalizzato su due aranci irrigati con diverse tecniche (piena irrigazione e disseccamento parziale delle radici). Il monitoraggio ERT dei processi in atto è effettuato sulla piccola scala (cioè sulla singola pianta) grazie alla combinazione di elettrodi superficiali ed in pozzo, permettendo così una acquisizione ed una rappresentazione tridimensionale del dato geofisico. Parallelamente ha luogo anche il monitoraggio agronomico, grazie al quale la traspirazione è determinata mediante misure di sap flow e di eddy covariance. I dati così ottenuti forniscono molte informazioni rispetto ai diversi processi in atto, sia atmosferici (traspirazione), che nel sottosuolo (assorbimento di acqua dal suolo). In particolare, il monitoraggio ERT in time-lapse è in grado di mostrare quali porzioni del dominio investigato siano soggette ad una diminuzione del contenuto idrico, la quale può essere collegata all’attività radicale. Nonostante la quantità e qualità dei dati a disposizione, l'interpretazione dei risultati (specialmente in termini quantitativi) risulta comunque piuttosto complessa. Una soluzione può essere fornita da un'appropriata modellazione idrologica, sebbene la scelta dell’approccio migliore richieda una specifica analisi matematica. Sotto quest’ottica abbiamo sviluppato un caso sintetico costituito da due modelli idrologici identici, dove uno quali descrive anche l'attività di una pianta d'arancio. Questi modelli hanno lo scopo di ricreare dei dataset riconducibili all'output delle misure ERT, senza però tutte le incertezze introdotte dall’acquisizione geofisica e dalla calibrazione del modello. La ricostruzione della "active root zone" è quindi ottenuta dalla combinazione di questi due modelli mediante l'espansione in serie di Taylor, con particolare attenzione alle approssimazioni così introdotte. L'obiettivo finale è quello di valutare questa procedura numerica per una futura applicazione ad uno dei casi studio reali presentati in questo lavoro.

Alle interazioni tra le diverse componenti del sistema suolo-pianta-atmosfera (SPA) è attribuito un ruolo critico nel ciclo idrologico e della biosfera terrestre. La comunità scientifica specializzata è sempre più consapevole della necessità di portare avanti studi a carattere interdisciplinare per la comprensione delle interazioni funzionali tra le risorse naturali ed i relativi problemi di sostenibilità del sistema SPA. All interno di tali studi interdisciplinari, l analisi delle interazioni suolo-radice risulta rilevante anche per la gestione ottimale dell'irrigazione, in particolare nelle zone caratterizzate da scarsa disponibilità idrica, come le aree mediterranee. A tal fine nasce l esigenza di valutare, ad alta risoluzione sia spaziale che temporale, le dinamiche idrologiche del sistema SPA, sino alla scala dell apparato radicale. Il contributo della tesi di dottorato consiste nell applicazione di tecniche di monitoraggio avanzate e minimamente invasive, per valutare gli scambi di massa ed energia all'interno del sistema SPA. L aspetto innovativo del lavoro di tesi consiste nell integrazione di tecniche geofisiche con misure micrometeorologiche e dati di traspirazione, al fine di interpretare alcuni dei principali processi di trasferimento di flussi nel sistema SPA (evapotraspirazione ed assorbimento radicale) in ambiente semi-arido. Tale approccio, è stato applicato a due Casi studio con l obiettivo di monitorare le complesse interazioni del sistema suolo-pianta, con particolare riferimento al processo di assorbimento radicale di alberi di agrume. Nel primo Caso studio, la tecnica della tomografia di resistività elettrica (ERT) tridimensionale è stata integrata con dati di traspirazione, misure micrometeorologiche e modellistica idrologica al fine di delineare la porzione di suolo non satura interessata dalle radici attive di un aranceto adulto. Nel secondo Caso studio, il monitoraggio ERT è stato integrato con misure di traspirazione al fine di delineare i pattern di RWU di alberi di arancio irrigati in regime di deficit. I risultati del lavoro di tesi dimostrano l abilità della tecnica di monitoraggio geofisico ERT nello spiegare le dinamiche idriche del suolo e la risposta fisiologica della pianta, in termini di attività delle radici nel processo di uptake, contribuendo, in tal senso, a migliorare la conoscenza dei processi di assorbimento radicale.

Cette recherche est issue d’une expérience qui s’est déroulée sur une période de cinq ans (2003-2008) dans un service de gastro-entérologie. L’auteur de cette thèse a éprouvé le besoin de solliciter quelques soignants ayant volontairement participé à un groupe de réflexion qui les réunissait régulièrement dans leur service ; ces instants leur permettaient d’évoquer leurs difficultés, leurs interrogations, leurs doutes, voire leurs souffrances. Bien des années plus tard, l’infirmier-doctorant qui a participé activement à cette initiative a voulu comprendre pourquoi cette expérience avait mobilisé certains soignants. Il importait de les rencontrer dix ans plus tard pour identifier avec le recul les bénéfices qu’ils avaient éventuellement retirés de ces temps d’éducation informelle. A la faveur des récits recueillis, une thèse s’est progressivement imposée : pour prendre soin des autres, le soignant n’a d’autres recours que de se raconter, entouré par ses pairs. C’est la figure du sujet apprenant qui émerge à travers ces récits d’apprentissage réalisés au sein d’un groupe. En faisant ces choix, ces professionnels accèdent aux quatre dimensions qui caractérisent le sujet : il est capable, sensible, situé socialement et en mesure de conduire une réflexion. C’est à la faveur de l’émergence de cette figure énigmatique d’un sujet apprenant au sein de ce groupe de réflexion que ces soignants construisent un rapport critique au savoir, se remettent en question et participent ainsi à un processus de développement professionnel et personnel tant pour eux-mêmes que pour les autres<br>This research is based on a five-year experience (2003-2008) in a gastroenterology department. The author of this thesis has felt the need to request some caregivers having voluntarily participated in a think tank which gathered them regularly in the department; these moments allowed them to express their hardships, their questioning, their doubts, even their suffering. Many years later, the nurse and PhD student who actively participated wanted to know why this experience had motivated some of the caregivers. It was important to meet them ten years later to identify with hindsight the benefits which they had possibly gained from these educational informal times. Thanks to the collected narratives, a hypothesis became obvious: to take care of others, the caregivers has no recourse but to talk, surrounded by his peers. This is the position of the learner which emerges through these learning narratives realized into group practice. By making their choice, these learners have access to four dimensions that characterize the subject : he is capable, sensitive, socially situated and able to lead a reflexion. By the emergence of this enigmatic learning subject within think tank, these caregivers make a criticism of their own knowledge, question themselves and so participate in a process of professional and personal self-growth both for themselves and others

The notion that agriculturally productive land may be treated as a relatively homogeneous resource at thewithin-field scale is not sound. This assumption and the subsequent uniform application of planting material,chemicals and/or tillage effort may result in zones within a field being under- or over-treated. Arising fromthese are problems associated with the inefficient use of input resources, economically significant yield losses,excessive energy costs, gaseous or percolatory release of chemicals into the environment, unacceptable long-term retention of chemicals and a less-than-optimal growing environment. The environmental impact of cropproduction systems is substantial. In this millennium, three important issues for scientists and agrariancommunities to address are the need to efficiently manage agricultural land for sustainable production, the maintenance of soil and water resources and the environmental quality of agricultural land.Precision agriculture (PA) aims to identify soil and crop attribute variability, and manage it in an accurate and timely manner for near-optimal crop production. Unlike conventional agricultural management where an averaged whole-field analytical result is employed for decision-making, management in PA is based on site-specific soil and crop information. That is, resource application and agronomic practices are matched with variation in soil attributes and crop requirements across a field or management unit. Conceptually PA makes economic and environmental sense, optimising gross margins and minimising the environmental impact of crop production systems. Although the economic justification for PA can be readily calculated, concepts such as environmental containment and the safety of agrochemicals in soil are more difficult to estimate. However,it may be argued that if PA lessens the overall agrochemical load in agricultural and non-agricultural environments, then its value as a management system for agriculture increases substantially.Management using PA requires detailed information of the spatial and temporal variation in crop yield components, weeds, soil-borne pests and attributes of physical, chemical and biological soil fertility. However,detailed descriptions of fine scale variation in soil properties have always been difficult and costly to perform.Sensing and scanning technologies need to be developed to more efficiently and economically obtain accurate information on the extent and variability of soil attributes that affect crop growth and yield. The primary aim of this work is to conduct research towards the development of an 'on-the-go' proximal soil pH and lime requirement sensing system for real-time continuous management of acid soil. It is divided into four sections.Section one consists of two chapters; the first describes global and historical events that converged into the development of precision agriculture, while chapter two provides reviews of statistical and geostatistical techniques that are used for the quantification of soil spatial variability and of topics that are integral to the concept of precision agriculture. The review then focuses on technologies that are used for the complete enumeration of soil, namely remote and proximal sensing.Section two comprises three chapters that deal with sampling and mapping methods. Chapter three provides a general description of the environment in the experimental field. It provides descriptions of the field site,topography, soil condition at the time of sampling, and the spatial variability of surface soil chemical properties. It also described the methods of sampling and laboratory analyses. Chapter four discusses some of the implications of soil sampling on analytical results and presents a review that quantifies the accuracy,precision and cost of current laboratory techniques. The chapter also presents analytical results that show theloss of information in kriged maps of lime requirement resulting from decreases in sample size. The messageof chapter four is that the evolution of precision agriculture calls for the development of 'on-the-go' proximal soil sensing systems to characterise soil spatial variability rapidly, economically, accurately and in a timely manner. Chapter five suggests that for sparsely sampled data the choice of spatial modelling and mapping techniques is important for reliable results and accurate representations of field soil variability. It assesses a number of geostatistical methodologies that may be used to model and map non-stationary soil data, in this instance soil pH and organic carbon. Intrinsic random functions of order k produced the most accurate and parsimonious predictions of all of the methods tested.Section three consists of two chapters whose theme pertains to sustainable and efficient management of acid agricultural soil. Chapter six discusses soil acidity, its causes, consequences and current management practices.It also reports the global extent of soil acidity and that which occurs in Australia. The chapter closes by proposing a real-time continuous management system for the management of acid soil. Chapter seven reports results from experiments conducted towards the development of an 'on-the-go' proximal soil pH and lime requirement sensing system that may be used for the real-time continuous management of acid soil. Assessment of four potentiometric sensors showed that the pH Ion Sensitive Field Effect Transistor (ISFET)was most suitable for inclusion in the proposed sensing system. It is accurate and precise, drift and hysteresis are low, and most importantly it's response time is small. A design for the analytical system was presented based on flow injection analysis (FIA) and sequential injection analysis (SIA) concepts. Two different modes of operation were described. Kinetic experiments were conducted to characterise soil:0.01M CaCl2 pH(pHCaCl2) and soil:lime requirement buffer (pH buffer) reactions. Modelling of the pH buffer reactions described their sequential, biphasic nature. A statistical methodology was devised to predict pH buffer measurements using only initial reaction measurements at 0.5s, 1s, 2s and 3s measurements. The accuracy of the technique was 0.1pH buffer units and the bias was low. Finally, the chapter describes a framework for the development of a prototype soil pH and lime requirement sensing system and the creative design of the system.The final section relates to the management of acid soil by liming. Chapter eight describes the development of empirical deterministic models for rapid predictions of lime requirement. The response surface models are based on soil:lime incubations, pH buffer measurements and the selection of target pH values. These models are more accurate and more practical than more conventional techniques, and may be more suitably incorporated into the spatial decision-support system of the proposed real-time continuous system for the management of acid soil. Chapter nine presents a glasshouse liming experiment that was used to authenticate the lime requirement model derived in the previous chapter. It also presents soil property interactions and soil-plant relationships in acid and ameliorated soil, to compare the effects of no lime applications, single-rate and variable-rate liming. Chapter X presents a methodology for modelling crop yields in the presence of uncertainty. The local uncertainty about soil properties and the uncertainty about model parameters were accounted for by using indicator kriging and Latin Hypercube Sampling for the propagation of uncertainties through two regression functions; a yield response function and one that equates resultant pH after the application of lime. Under the assumptions and constraints of the analysis, single-rate liming was found to be the best management option.