Made available in DSpace on 2016-04-26T18:17:29Z (GMT). No. of bitstreams: 1 Barbara Conceicao de Oliveira Barbosa.pdf: 453357 bytes, checksum: d90d23e758ee4e0da96fd7c7ed36d91f (MD5) Previous issue date: 2008-10-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The present Master s Degree Dissertation is intended to analyze the technological dependence its origins, its state-of-the-art and its consequences in the sphere of the relationship between human being and interactive media. The research contexts, of an exclusively theoretical nature, is the cyberculture, understood as a social organization of epoch, originated from the technological development that followed the Second World War. The main objective is to analyze the dependence phenomenon to which the cybercultural civilization is subject. The research problem lies in the following questionings: how a relationship so presented is configured? Which factors favor it? In the social-historic sphere, does dependence provides the preservation of technological lifestyles? Would it be present both in the collective plan and in the individual plan? As a main hypothesis, the study redefines and overvalues as dependence the strict social subjects bond to interactive technologies and networks, a bond whose analysis should consider the civilizatory and anthropological aspects involved, as it implies, simultaneously, recent history, society and individual. The research fundamentation privileges theoretical proposals articulated by the criticism category and consolidated in the last twenty years, based on the following authors: David Harvey, Fredric Jameson, Krishan Kumar and Jean-François Lyotard (post modernity); Paul Virilio (the concept of dromology); Eugênio Trivinho (cyberculture, cybercultural dromocracy and glocal phenomenon); Francisco Rüdiger and David Le Breton (cybercultural imaginary), Philippe Breton (communication as an utopian value); Pierre Bourdieu (concept of habitus); Vilém Flusser (technical image); Jean Baudrillard (the concept of excess). The reflection also incorporates references to researches who study the pathological use of Internet, such as Rosa Maria Farah and Denise Razzouk, among other authors and theoretical-epistemological perspectives. In relation to the achieved results, we can highlight, as favoring dependence, the context of cybercultural dromocracy (the velocity regime in the digital era), the glocal context (real-time living) and the inherent characteristics to interactive glocal, such as velocity, virtuality, deterritorialization, personalization, etc. This panorama gives cause to practices that, incorporated by the subject, are objectified in the glocalized habitus and affect it in body and in subjectivity. Such transformations and their consequences require gradual deepening in researches about the factors that endanger them, which justifies the present work. The research is inserted in the Culture and mediatic environments Research Line of PEPGCOS-PUC-SP, as it deals with the interactive technologies impact on the social-historic and cultural spheres; and finds support in the Communication area in Brazil, beside researches more and more concerned about cyberculture and its communicational practices / A presente Dissertação de Mestrado se destina à análise da dependência tecnológica suas origens, seu estado da arte e suas conseqüências no âmbito da relação entre ser humano e media interativos. O contexto da pesquisa, de natureza exclusivamente teórica, é o da cibercultura, entendida como organização social de época, originada do desenvolvimento tecnológico posterior à Segunda Guerra Mundial. O principal objetivo é analisar o fenômeno da dependência à qual está sujeita a civilização cibercultural. O problema de pesquisa reside nos seguintes questionamentos: como se configura uma relação assim posta? Quais fatores a favorecem? No âmbito social-histórico, a dependência propicia a conservação de estilos de vida tecnológicos? Estaria presente tanto no plano coletivo quanto no individual? Como hipótese principal, o estudo redefine e sobrevalora como dependência , o vínculo estrito dos sujeitos sociais às tecnologias e redes interativas, vínculo cuja análise deve considerar os aspectos civilizatórios e antropológicos envolvidos, pois implica, a um só tempo, história recente, sociedade e indivíduo. A fundamentação da pesquisa privilegia propostas teóricas articuladas pela categoria da crítica e consolidadas nos últimos vinte anos, com base nos seguintes autores: David Harvey, Fredric Jameson, Krishan Kumar e Jean-François Lyotard (pós-modernidade); Paul Virilio (conceito de dromologia); Eugênio Trivinho (cibercultura, dromocracia cibercultural e fenômeno glocal); Francisco Rüdiger e David Le Breton (imaginário cibercultural), Philippe Breton (comunicação como valor utópico); Pierre Bourdieu (conceito de habitus); Vilém Flusser (imagem técnica); Jean Baudrillard (conceito de excesso). A reflexão incorpora, também, referências a pesquisadores que estudam o uso patológico da internet, como Rosa Maria Farah e Denise Razzouk, entre outros autores e perspectivas teórico-epistemológicas. Em relação aos resultados alcançados, destacam-se, como favorecedores da dependência, o contexto da dromocracia cibercultural (regime da velocidade na era digital), o contexto glocal (vivência em tempo real) e as características inerentes ao glocal interativo, como a velocidade, a virtualidade, a desterritorialização, a personalização etc. Esse panorama enseja práticas, que, incorporadas pelo sujeito, são objetivadas no habitus glocalizado e o afetam no corpo e na subjetividade. Tais transformações e suas conseqüências requerem gradual aprofundamento nas pesquisas dos fatores que as engendram, o que justifica o presente trabalho. A pesquisa se insere na Linha de Pesquisa Cultura e ambientes midiáticos do PEPGCOS-PUC-SP por versar sobre o impacto das tecnologias interativas nos âmbitos social-histórico e cultural; e encontra guarida na área da Comunicação no Brasil, ao lado de pesquisas cada vez mais preocupadas com a cibercultura e suas práticas comunicacionais

台灣地區在2010年的行政區域調整中，有三個區域進行縣市合併，合併後的縣市其選區必須重新劃分，而進行劃分時有三個因素可以做為縣市合併後衍生之選區劃分原則，分別是縣市融合、大市效應與優勢現象。這三個因素在以往的選區劃分中甚少被提及，因此本論文特別討論考慮這三個因素的選區劃分。 由於大市效應或優勢現象產生的原因是單一選區中有太多的選舉人口來自縣市合併前的同一行政區，因此我們在劃分前處理中，先對人口過多的行政區進行分割，然後進行選區劃分。為促進縣市融合，我們優先考慮將原縣市交界區域的行政區域劃分至選區，然後才考慮非交界區的行政區域。劃分的過程中，我們參考最多限制優先的原則，透過貪婪演算法進行劃分，劃分結束後再進行選區調整，以求能滿足中選會對選區人口數等相關的規定。 我們在論文中提出了選區評估的指標，可以對縣市融合、大市效應與優勢現象進行衡量與評估，以便作為劃分結果的比較與參考。 最後我們透過對合併後的高雄縣市進行選區劃分，以說明我們整體的概念與方法。根據我們的劃分原則與方法，我們的劃分結果產生6個縣市融合的選區，而中選會所公布的選區劃分結果，沒有任何符合縣市融合精神的選區。同時，相較於中選會的結果，我們的劃分方式有較好的大市效應指標與優勢現象指標。 / During the administrative district adjustment of Taiwan in 2010, three regions conducted the city and county merges. The electoral districts must be redistricted after these merges. There are new issues, related to the merge of city and county, which have seldom being discussed before, namely, the city-county integration, the overpopulation-region effect, and the dominance phenomenon. In this thesis, we will consider these issues as the new principles to be included in electoral districting. The reason that causes overpopulation-region effect or dominance phenomenon is due to too much of population comes from the same administrative district in the city of county prior to the merge. One could avoid these by dividing the overpopulation borough before carrying out the electoral districting. In order to promote the city and county integration, we give priority to these administrative districts on the junction regions of the original city and county configurations before considering the administrative districts on the non-junction regions. The most constraint principles and greedy algorithms are employed in the actual electoral districting processes. After the first districting, we conduct a region adjustment to comply with the regulations of the Central Election Commission (CEC). We also proposed the assessment indices that can be used to evaluate the possible effects due to the city-county integration, the overpopulation-region effect, and the dominance phenomenon. Using these indices, one can compare the results of various districting outcomes. Finally, we illustrated our idea and methods by actually districting the merged region of Kaohsiung city and county. According to our mechanism, we produced six city-county integrated electoral districts where no city-county integrated electoral district was found in the CEC’s districting results. In addition, the districting results produced by our method have better overpopulation-region effect index and better dominance phenomenon index than that announced by CEC.

Esta tesis doctoral se centra en la prospección de lo fantástico en la narrativa breve del escritor francés Honoré de Balzac (1799-1850). La investigación se estructura en cinco capítulos, más el dedicado a las referencias bibliográficas. Tras los aspectos de tipo teórico e histórico ligados a lo fantástico, se analizan las circunstancias culturales, ideológicas y personales que intervinieron en la gestación de lo fantástico balzaquiano. A continuación se estudia la articulación formal de lo fantástico en los once textos balzaquianos seleccionados. Siguiendo el modelo de análisis propuesto por Joël Malrieu se han estudiado cuatro categorías: personaje, fenómeno irracional, espacio-tiempo y narrador.Del estudio se desprende que los relatos fantásticos balzaquianos se ajustan a la caracterización estética del género que establece Malrieu. Balzac conoce y domina la técnica compositiva inherente a lo fantástico en el relato breve, pudiendo afirmar que esta faceta creativa va más allá de una simple concesión a la moda pasajera del momento. / This doctoral thesis focuses on the search for the fantastic ingredient in the short stories by the French writer Honoré de Balzac (1799-1850). The research is organized in five chapters, plus the bibliography.After examining the theoretical and historical aspects linked to the fantastic component, we analyze the cultural, ideological and personal circumstances which took part in the gestation of the fantastic elements in Honoré de Balzac. Afterwards, we study the formal articulation of this in the eleven texts by Balzac that we have selected. Following the analysis scheme proposed by Joël Malrieu, we have studied four categories: character, irrational phenomenon, space-time and narrator. From this research, we can conclude that Honoré de Balzac short stories come into the aesthetic characterization of the genre established by Malrieu. Balzac knows very well the writing technique inherent to the fantastic ingredient in the short story. Definitely, we can state that this creative facet is more than a simple concession to the temporary fashion of his time.

In this thesis, the design and implementation of a Portable Feedback Active Noise Controller Headphone System, which is based on Texas Instruments TMS320VC5416PGE120 Fixed Point DSP, is described. Problems resulted from fixed-point implementation of LMS algorithm and delays existing in digital ANC implementation are determined. Effective solutions to overcome the aforementioned problems are proposed based on the literature survey. Design of the DSP based control card is explained and crucial points about analog-digital-mixed board design for noise sensitive applications are explained. Filtered input LMS algorithm, filtered input normalized LMS algorithm and filtered input sign-sign LMS algorithm are implemented as adaptation algorithms. The advantages and disadvantages of using modified LMS algorithms are indicated. The selection of the parameters of these algorithms is based on theoretical results and experiments. The real time performances of different adaptation algorithms are compared with each other as well as with a commercial analog ANC headphone under different types of artificial and natural noise signals. Moreover, practical conditions such as put on - put off case and dynamic range overflow case are handled with additional software implementations. It is shown that adaptive ANC systems improve the noise reduction significantly when the noise is within a narrow frequency range and this reduction can be applied to a wider frequency range. It is also shown that the problems of digitally implemented adaptive filters which are based on tracking capability, stability, dynamic range and portability can be fixed to challenge with the analog commercial ANC systems.

Nanostructured materials play a vital role in almost all aspects of science and technology in the 21st century. The materials include nanoparticles, nanofilms, biological membranes etc. whose physicochemical properties are size-dependent. Thin films have wide range of applications in various branches of science. One of the efficient methods to form miniaturized structures for device applications is to fabricate nanostructured films on different substrates. Surfactant assembly on metallic and non-metallic surfaces based on self assembly and Langmuir-Blodgett technique offers a unique way to form thin films at molecular levels. The process of formation of unimolecular assemblies gives the flexibility of tuning the properties of underlying substrates for various applications including wetting characteristics, lubrication, passivation, mimicking biological phenomena etc. Towards this direction, self assembled monolayers (SAMs) of alkanethiols on gold and silver surfaces have been studied comprehensively for the past two decades. The reported literature on short chain length thiol-based monolayers is however, limited since the formation using conventional methods yield poor quality monolayers. The short chain length monolayers are useful in various applications like tribology, layer-by-layer assemblies, biosensors etc. Hence, it is essential to reproducibly form SAMs of various chain lengths and understand their properties. The present study is related to the formation of SAMs of alkanethiols and diselenides on gold and silver surfaces to form ordered and well-oriented monolayers. Monolayers of varying chain lengths (CH3(CH2)nSH where n = 3, 5, 7, 9, 11, 15) have been formed on gold and silver surfaces using different methods, (1) adsorption from neat thiols; (2) adsorption under electrochemical control and (3) adsorption from alcoholic solutions of the thiols. The characteristics features of the SAMs have been followed based on three different aspects, (i) structure and stability of the methylene groups (ii) interfacial characteristics involving the end group and the solvent and (iii) metal-head group interactions. The structure and stability of the monolayers have been followed based on vibrational spectroscopy and electrochemistry under different environment including thermal perturbations. The stability of the SAMs at different temperatures and subsequent changes associated with the orientation / packing has been monitored both in the dry state using reflection absorption infrared spectroscopy (RAIRS) and under electrochemical conditions using cyclic voltammetry and impedance analysis. Monolayers adsorbed from neat thiols show superior quality in terms of stability and structural arrangement. Short chain thiols with n = 3, 5, 7 show substantial stability when the adsorption is carried out from neat thiols. Figure 1 shows the RAIR spectra of hexanethiol SAM on gold adsorbed by three different procedures. Monolayers adsorbed under potential control behave very similar to the monolayers adsorbed from neat thiol as for as stability and structural orientation are concerned. Monolayers prepared using conventional methods of adsorption from alcoholic solutions are of inferior quality in terms of stability and arrangement especially for the short chain lengths. This is likely to be due to the fact that monolayers prepared using conventional methods may have intercalated solvent molecules within the monolayer assembly that degrade the integrity of the SAM leading to poor quality. The blocking characteristics of the monolayers for diffusing redox couple have been followed by determining the heterogeneous electron transfer rate constant using electrochemical techniques. The spectroscopic data and the electrochemical data follow similar trend indicating the superior quality of monolayer adsorbed from neat thiol in terms of stability as compared to conventionally prepared monolayers. Figure 1. RAIR spectra of hexanethiol-SAMs on Au(111) surface at 25C. The monolayers are formed by adsorption (A) from neat thiol (B) under potential control and (C) from alcoholic solution of the thiol. Wavenumber (cm-1) The interfacial characteristics of the monolayers (effect of end group functionality on the solvent properties) have been monitored on the basis of capacitance, contact angle and atomic force microscopy- measurements. Well-organized monolayers behave like good capacitors with relatively low values of double layer capacitance in presence of a liquid electrolyte as compared to the expected values based on known thickness and dielectric constant of the SAMs. This behavior can be explained by invoking the depletion of water density at the methyl terminated SAM-water interface where the solvent properties are different from that of bulk. Variation of one such property, dielectric constant, has been mapped using force measurement based on AFM. Dielectric constant of water changes from the bulk value of 78 to a low value as given in figure 2. This cross-over occurs within a span of 1-3 nm depending on the chain length of the thiol. Of the three procedures used, the ones based on the use of neat thiol and electrochemical adsorption result in well-oriented alkyl chains followed by highly oriented methyl terminal groups. This is responsible for the high hydrophobic nature of the interface and the subsequent observation of interfacial water properties. The SAMs prepared from ethanol fail to show the hydrophobic effects. Hydrophilic monolayers (NH2 terminated monolayers) fail to show depletion of water density at the interface indicating the importance of end group functionality in altering the interfacial characteristics of the monolayer. Figure 2. Spatial variation of dielectric permittivity of water at the hexanethiol SAM - water interface. The SAM is formed on gold (111) surface; (a) from ethanolic solution of the thiol (b) under electrochemical control (c) from neat thiol. The origin on the x-axis is the position of the methyl groups of SAM and the direction towards right side is in to the bulk water. The well-oriented SAMs have been used to follow the adsorption of a biopolymer. Zein protein is a prolamine of maize and is projected to be a biocompatible coating for food products and food containers. Hence, it is essential to prepare impermeable coatings of zein with different surface wetting properties. The adsorption of zein on highly ordered SAMs with hydrophobic or hydrophilic end group functionality has been studied and the orientation of the protein followed using spectroscopy, microscopy and electrochemistry. It is observed that zein shows higher affinity towards hydrophilic than hydrophobic surfaces with small foot print size on the Figure 3. Orientation of zein protein on hydrophilic and hydrophobic SAM as deciphered from the experimental data. hydrophilic surface resulting in large surface coverage. Figure 3 shows the schematics of zein deposits on hydrophilic and hydrophobic SAM surfaces determined based on spectroscopy, quartz crystal microbalance and electrochemical studies. The AFM shows cylindrical, rod-like and disc-like features of zein on hydrophilic surfaces that form the base units for the growth of cylindrical structures of zein. The published literature on the studies on SAMs on silver surfaces reveals that there is no consensus on the structure of the monolayers on silver. This may be due to the difficulty in getting pristine oxide-free surfaces in the case of silver and this is likely to affect the monolayer quality. Hence, it is decided to prepare SAMs of alkanethiols on silver and study their characteristics. Subtle differences between the monolayers adsorbed from neat thiol and from alcoholic solutions of thiols have been observed in terms of stability and permeability. Atomic force microscopic studies illustrate the presence of depletion of water at the SAM-aqueous interface. Diselenide-based monolayers have been formed on gold to understand the head group-substrate interactions on the monolayer properties. The disorder observed on short chain diselenide-based monolayers formed from alcoholic solutions can be eliminated by adsorption from neat compounds as described for the thiols. A preliminary account on the stability of SAMs under hydrodynamic conditions has been given based on rotating disc electrode voltammetry. It is observed that the SAMs get well-ordered when the electrode is rotated at a fast rate leading to the hypothesis that the monolayer assembly gets annealed as a function of the rotation rate. The thesis is planned as follows: Chapter 1 gives general introduction about organic thin films with particular emphasis on self-assembled monolayers on gold and silver, their characteristics in terms of stability, interfacial properties and adsorption behaviour. Chapter 2 deals with the experimental methodologies and schematics used for the preparation and characterization of the monolayers. Chapter 3 is on the contribution of alkyl spacer to the stability of the monolayers studied using spectroscopy and electrochemistry. Chapter 4 deals with the interfacial properties of the SAMs in presence of aqueous medium. In order to emphasize the importance of the terminal functional groups, adsorption of zein has been demonstrated on surfaces of controlled wettablity. Chapter 5 explains the formation and stability of monolayers of short and long chain alkyl diselenides on gold surfaces. Chapter 6 gives the structural and interfacial characteristics of alkanethiol monolayers on silver surfaces. The stability and subsequent changes of alkanethiol monolayers under hydrodynamic conditions has been discussed in the appendix section.(For fig pl refer pdf file.)

The intention behind this research was to reveal through two interpretive, inter-related studies the perceived needs of differently-labelled youth, collectively addressed in this thesis as ‘the New Generations’, exploring potentially viable ways of working with them in education. The first study focused on youth labelled Indigos, and the second study focused on exploring a possible way of working with the New Generations according to experienced teachers. Both studies drew on lived experience and opinions of educators who have acquired extensive experience respectively with the Indigo phenomenon and with the psychosynthetic educational model. The first study’s results revealed not only Indigos’ self-actualising and self-transcending characteristics and needs, but also indicated that holistic approaches to education appeared to have been successful with them. A further analysis of characteristics observed by special education experts indicated that differently-labelled youth also appear to be motivated by self-actualising and self-transcending tendencies, which highlighted the relevance of investigating holistic models for potential integration in mainstream education. Psychosynthesis was chosen for investigation in the second study, in that besides addressing self-actualising/transcending needs, it also integrates them within the psyche. The study explored how recent psychosynthesis-based educational projects might inform, and contribute to, holistic and mainstream education. Some innovative potential contributions to both holistic and mainstream education were found. Recent research on current tendencies, educational futures and global trends affecting a changing world would appear to emphasise the relevance of the contributions offered by the psychosynthesis model, hence to suggest the potential appropriateness of their fuller integration in mainstream education. However, an examination of study results and of the relevant literature on practices seems to indicate a tendency to transmit knowledge from past to future generations, irrespective of possibly changed needs, in both mainstream and holistic education. It is suggested that this potentially biased way of educating youth might need to be addressed on both fronts.

Βασισμένη στην «κοινωνικό- πολιτισμική, ιστορική προσέγγιση» η παρούσα έρευνα συνιστά μια προσπάθεια αξιοποίησης θεωρητικών εργαλείων και μεθοδολογικών αρχών από το συγκεκριμένο θεωρητικό πλαίσιο κατά την ερευνητική διαδικασία της ανίχνευσης παραστάσεων παιδιών νηπιαγωγείου σε σχέση με τα σύννεφα. Τα επιμέρους ερευνητικά ερωτήματα που τίθενται αφορούν στο πώς αντιλαμβάνονται τα παιδιά του νηπιαγωγείου τα σύννεφα, πώς συγκροτούν τις σχετικές νοητικές τους παραστάσεις και πώς διαχειρίζονται, αναδομούν, μετασχηματίζουν τις παραστάσεις αυτές σε διαφορετικές κοινωνικές περιστάσεις. Δείγμα της έρευνας αποτέλεσαν δέκα έξι (16) μαθητές δημόσιου νηπιαγωγείου αστικής περιοχής της περιφέρειας Δυτικής Ελλάδας. Η συλλογή των δεδομένων έγινε μέσω διευρυμένων ανοικτού τύπου συζητήσεων ανά δύο παιδιών του δείγματος και της ερευνήτριας. Η παρατήρηση, ανάλυση και παρουσίαση των αποτελεσμάτων έγινε με άξονα τη «μέθοδο τριπλής εστίασης» της Rogoff (προσωπική εστίαση, διαπροσωπική, πλαισίου). Τα αποτελέσματα που προκύπτουν αφήνουν να διαφανεί, πέραν από τις νοητικές παραστάσεις των παιδιών, ο τρόπος με τον οποίο κοινωνικά- πολιτισμικά και ιστορικά στοιχεία και εργαλεία διαμεσολαβούν στη σκέψη τους και στις διαδικασίες συγκρότησής της. Συμπεραίνεται επομένως πως, μέσω της οπτικής που μελετάται, οδηγούμαστε σε μια διευρυμένη και ολιστική προσέγγιση της παιδικής σκέψης αποκεντρωμένη από την αυστηρά εννοιολογική προοπτική του πιαζετικού προτύπου. Η έρευνα καταλήγει με την ανάδειξη σημαντικών ερευνητικών προοπτικών σε θεωρητικό, εμπειρικό και διδακτικό επίπεδο. / This Master Thesis, based on the “sociocultural-historical” approach on child thought development, constitutes an attempt of exploiting the theoretical tools and methodology principles from this particular theoretical field during research procedures of tracing kinder-garden children views on clouds. The various raised research questions are related to how kinder-garden children comprehend clouds, how they construct cloud-related conceptual schemes and how they manage, restructure and transform these schemes in different social circumstances. The research sample consisted of sixteen (16) public urban-area kinder-garden students in the vicinity of Western Greece. The data collection has been done using expanded, open type, conversations between the sample’s children in pairs and the researcher. The observation, analysis and presentation of results has been done using Rogoff’s “three foci approach” (personal, interpersonal, contextual or cultural-institutional focus of analysis). Through those results, beyond conceptual schemes, the way that socio-cultural and historical elements and tools intercede in children thinking and the process of structuring it, is highlighted. It can be concluded that, through the studied perspective, we are led to an expanded and holistic approach of the sample’s children thinking, which is detached from the strictly conceptual viewpoint. The outcome of the Master Thesis research results has highlighted the important research potentials of the sociocultural approach in theoretical, empirical and didactic level.

No description available.

Icicles are a ubiquitous and picturesque feature of cold winter weather. Their familiar form emerges from a subtle interplay between the solidification dynamics of ice and the gravity-driven flow of the thin water film flowing over their evolving surface. The latent heat released by freezing is advected by the water film and ultimately carried away by the surrounding sub-zero air, which is also flowing. Like many processes far from equilibrium, icicle growth can exhibit nonlinear pattern formation. While scaling theory predicts that icicles converge to `platonic', self-similar shapes, natural icicles often exhibit regular ripple patterns about their circumference, which are due to a morphological instability. This thesis presents a comprehensive experimental study of icicles that sheds new light on the dynamics of their growth and the origin of their form. A table-top apparatus was designed and built for the controlled growth of icicles, under different conditions of temperature, water supply rate, ambient air motion, and water purity. Image analysis and Fourier methods were used to examine their morphology. Contrary to theoretical expectations, ripples do not appear on icicles made from pure water. Instead, ripples grow and travel on icicles made from salt solutions, even at very low concentrations. The addition of non-ionic surfactant or dissolved gases does not produce ripples, unless ionic impurities are also present. The ripple wavelength is independent of time and growth conditions. The ripple amplification rate and traveling velocity vary weakly with the ionic concentration, as do the tip and radial growth speeds of the icicle. While the tip and radial growth also depend on the ambient temperature and input mass flux, the ripple dynamics is not correlated with extrinsic conditions. If the ambient temperature or input mass flux is sufficiently low, the tip growth only advances for a short period of time before it ceases. After cessation, the shape of the icicle deviates increasingly from self-similarity. The most self-similar icicles are made from pure water with the surrounding air gently stirred, whereas icicles made from impure water in still air tend to grow multiple tips.

La circulation extracorporelle (CEC) déclenche une réaction inflammatoire systémique, un dommage d’ischémie-reperfusion (I-R) et une dysfonction de l’endothélium dans la circulation pulmonaire. L’hypertension pulmonaire (HTP) est la conséquence de cette cascade de réactions. Cette HTP augmente le travail du ventricule droit et peut causer sa dysfonction, un sevrage difficile de la CEC et une augmentation des besoins de vasopresseurs après la chirurgie cardiaque. L’administration de milrinone et d’époprosténol inhalés a démontré une réduction de la dysfonction endothéliale dans l’artère pulmonaire. Le but de ce travail est d’évaluer différents types de nébulisateur pour l’administration de la milrinone et d’évaluer l’effet du traitement préventif de la combinaison de milrinone et époprosténol inhalés sur les résultats postopératoires en chirurgie cardiaque. Deux études ont été conduites. Dans la première, trois groupes de porcelets ont été comparés : (1) groupe milrinone avec nébulisateur ultrasonique ; CEC et reperfusion précédées par 2,5 mg de milrinone inhalée, (2) goupe milrinone avec nébulisateur à simple jet ; CEC et reperfusion précédées par 2,5 mg de milrinone inhalée et (3) groupe contrôle ; CEC et reperfusion sans traitement. Durant la procédure, les paramètres hémodynamiques, biochimiques et hématologiques ont été mesurés. Après sacrifice, la relaxation endothélium dépendante de l’artère pulmonaire à l’acétylcholine et à la bradykinine a été étudiée en chambres d’organe. Nous avons noté une amélioration de la relaxation de l’endothélium à la bradykinine et à l’acétylcholine dans le groupe avec inhalation de milrinone avec le nébulisateur ultrasonique. Dans la deuxième étude, une analyse rétrospective de 60 patients à haut risque chirurgical atteints d’HTP et opérés à l’Institut de Cardiologie de Montréal à été effectuée. Deux groupes ont été comparés : (1) 40 patients ayant reçu la combinaison de milrinone et d’époprosténol inhalés avant la CEC (groupe traitement) et (2) 20 patients avec des caractéristiques préopératoires n’ayant reçu aucun traitement inhalé avant la CEC (groupe contrôle). Nous avons observé que les besoins en support pharmacologique vasoactif était réduit à 12 heures et à 24 heures postopératoires dans le groupe traitement. L’utilisation de la nébulisation ultrasonique a un impact favorable sur l’endothélium de l’artère pulmonaire après la CEC lorsque comparée à la nébulisation standard à simple jet. Le traitement préventif des patients atteints d’HTP avec la combinaison de milrinone et d’époprosténol inhalés avant la CEC est associé avec une diminution importante des besoins de support vasoactif aux soins intensifs dans les 24 premières heures après la chirurgie. / Cardiopulmonary bypass (CPB) triggers a systemic inflammatory response, an ischemia-reperfusion (I-R) injury and endothelial dysfunction in the pulmonary circulation. Pulmonary hypertension (PH) is a consequence of this insult. The latter increases right ventricle work and may cause difficult separation from cardiopulmonary bypass (CPB) and increased vasoactive requirements after cardiac surgery. Administration of inhaled milrinone or epoprostenol has been shown to reduce endothelial dysfunction in the pulmonary artery. The aim of this work is to evaluate different nebulisators for the administration of milrinone and to evaluate the effect of pre-emptive treatment with inhaled milrinone and epoprostenol on postoperative outcome in cardiac surgery. Two different studies were done. In the first, three groups of swine were compared: (1) ultrasonic nebulisator inhaled milrinone group; CPB and reperfusion preceded by 2.5 mg inhaled milrinone, (2) simple jet nebulisator inhaled milrinone group; CPB and reperfusion preceded by 2.5 mg inhaled milrinone, and (3) control group; CBP 90 minutes followed by 60 minutes of reperfusion without treatment. During the procedure, hemodynamic, biochemical and hematologic parameters were measured. After sacrifice, pulmonary arterial endothelium-dependent relaxations to acetylcholine and bradykinin were studied in organ chamber experiments. There was a greater improvement in endothelium-dependent relaxations to bradykinin and acetylcholine in the ultrasonic nebuliser inhaled milrinone group compared with the control group and the simple jet nebulisator inhaled milrinone group. In the second study, a retrospective analysis of 60 high-risk surgical patients with PH operated at the Montreal Heart Institute was conducted. Two groups were compared: (1) 40 patients received both inhaled milrinone and inhaled epoprostenol before CPB (treatment group); (2) 20 patients with equivalent preoperative data did not receive any inhaled medication before CPB during the same period (control group). Post-operative vasoactive requirement was reduced at 12 hours and 24 hours post-operatively in the treatment group. Use of ultrasonic nebulisation has a favourable impact on the pulmonary endothelial dysfunction induced by CPB when compared to the simple jet nebulisation traditionally used. Pre-emptive treatment of PH with a combination of inhaled milrinone and epoprostenol prior to CPB was associated with a significant reduction in vasoactive support in the intensive care unit during the first 24 hours after cardiac surgery.