Global oceanic emission of ammonia: Constraints from seawater and atmospheric observations

Current global inventories of ammonia emissions identify the ocean as the largest natural source. This source depends on seawater pH, temperature, and the concentration of total seawater ammonia (NHx(sw)), which reflects a balance between remineralization of organic matter, uptake by plankton, and nitrification. Here we compare [NHx(sw)] from two global ocean biogeochemical models (BEC and COBALT) against extensive ocean observations. Simulated [NHx(sw)] are generally biased high. Improved simulation can be achieved in COBALT by increasing the plankton affinity for NHx within observed ranges. The resulting global ocean emissions is 2.5 TgN a−1, much lower than current literature values (7–23 TgN a−1), including the widely used Global Emissions InitiAtive (GEIA) inventory (8 TgN a−1). Such a weak ocean source implies that continental sources contribute more than half of atmospheric NHx over most of the ocean in the Northern Hemisphere. Ammonia emitted from oceanic sources is insufficient to neutralize sulfate aerosol acidity, consistent with observations. There is evidence over the Equatorial Pacific for a missing source of atmospheric ammonia that could be due to photolysis of marine organic nitrogen at the ocean surface or in the atmosphere. Accommodating this possible missing source yields a global ocean emission of ammonia in the range 2–5 TgN a−1, comparable in magnitude to other natural sources from open fires and soils.

O currículo das ciências físicas e naturais na perspetiva docente: saberes profissionais e possibilidades de ação

O atual contexto social de aceleração exponencial, resultante de alterações políticas, económicas e do acesso imediato a um extenso conjunto de informações e a um manancial de desenvolvimentos científicos e tecnológicos, cujas implicações são imprevisíveis e transversais a diferentes setores, está em dissonância com as características do modelo escolar dominante e a naturalizada ‘gramática da escola’ (Formosinho & Machado, 2008; Nóvoa, 2009a; Tyack & Tobin, 1994). Este desfasamento, amplificado em países com sistemas de ensino de matriz centralizada, resvala entre uma ação docente acrítica e executora e, em oposição, uma ação docente de natureza profissional, caracterizada por um alinhamento entre o desenvolvimento profissional e a afirmação da especificidade do conhecimento profissional docente, enquanto saber que se constrói na interação com os outros, com o próprio, nos e sobre os contextos de prática. A implementação do processo de reorganização curricular do ensino básico (Decreto-Lei n.º 6/2001, de 18 de janeiro) redefiniu o currículo nacional segundo duas perspetivas: a nacional e a local, veiculando uma conceção curricular flexível e emancipatória, isto é, uma proposta curricular que confere aos professores autonomia no desenvolvimento e gestão do currículo, instigando-os à realização de práticas curriculares com intencionalidade pedagógica estratégica. Neste sentido, a pretensão desta investigação situou-se ao nível da problematização de saberes profissionais e da concetualização de algumas possibilidades de ação tangenciais à capacidade de autotransformação de cada profissional docente e da escola. As opções metodológicas consideradas visaram, sobretudo, compreender quais os possíveis conhecimentos profissionais mobilizados por professores de Ciências Físicas e Naturais, em particular ao nível do desenvolvimento e gestão do currículo desta área curricular. Assim, perspetivado sob a forma de questão enquadradora, o problema que esteve na génese desta investigação assume a seguinte formulação: Que conhecimento mobilizam professores do ensino básico no desenvolvimento e na gestão do currículo das Ciências Físicas e Naturais? De que forma e com que ações poderá ser potenciado esse conhecimento nos processos de ensino e aprendizagem? O estudo empírico que sustentou este projeto de investigação organizou-se em dois momentos distintos. O primeiro, de natureza predominantemente quantitativa e dimensão de análise extensiva, envolveu a administração de um inquérito por questionário a professores de Ciências Físicas e Naturais que, no ano letivo de 2006/2007, se encontravam a lecionar em escolas públicas com 2.º e 3.º ciclos afetas à Direção Regional de Educação do Norte e ao, anteriormente, designado Centro de Área Educativa de Aveiro. Com um enfoque preponderantemente qualitativo, o segundo momento do estudo decorreu ao longo do ano letivo de 2007/2008 num agrupamento de escolas da região norte do país e consistiu na realização de entrevistas a oito professores de Ciências Físicas e Naturais, à coordenadora do departamento de Matemática e Ciências Experimentais e aos presidentes do Conselho Pedagógico e do Conselho Executivo. Ao longo do ano letivo, os professores de Ciências Físicas e Naturais desenvolveram, igualmente, um percurso formativo cuja ênfase se situava ao nível da adequação do desenvolvimento e gestão do currículo desta área disciplinar. As técnicas de tratamento de dados privilegiadas foram a análise estatística e a análise de conteúdo. Os resultados deste estudo apontam para a prevalência de uma ação docente desprovida de intencionalidades pedagógica e curricular ou de integração na construção do corpo geral do saber, designadamente ao nível dos processos de desenvolvimento e gestão do currículo. Não obstante alguma familiarização com conceitos inerentes à dimensão do conhecimento do currículo, os indicadores de reapropriação ao nível da ação docente foram escassos, denunciando a presença de constrangimentos no domínio teórico das orientações curriculares nacionais e locais, bem como no desenvolvimento de práticas curriculares articuladas e estrategicamente definidas. Por outro lado, o predomínio de uma ação docente tendencialmente acrítica, de matriz executora, associada ao cumprimento de normativos legais e de rotinas e burocracias instituídas, indiciou fragilidades ao nível do conhecimento profissional configurado como mobilização complexa, organizada e coerente de conhecimentos científicos, curriculares, pedagógicos e metodológicos, em função da especificidade de cada situação educativa e cuja finalidade é a otimização da aprendizagem do aluno. O percurso formativo afigurou-se como um espaço de partilha e de reflexão colegial, propício ao desenvolvimento de ações que se inserem numa perspetiva de ‘action learning’, possibilitando a reflexão e a aprendizagem através de ações empreendidas em função de práticas educativas. As possibilidades de ação remetem para a integração da formação contínua em contexto, com intencionalidades pedagógicas e curriculares estrategicamente definidas, e a problematização da formação inicial e contínua dos professores, envolvendo as perspetivas de diferentes atores educativos e de investigadores educacionais.

O questionamento como elemento integrador do blogue nas aulas de ciências

A investigação sobre a promoção do questionamento na relação pedagógica revela ser uma estratégia que valoriza o papel do aluno enquanto aquele que aprende, alterando a forma como as aulas são vividas por alunos e professores. Perante a inexistência de estudos que ensaiem o estímulo ao questionamento e, simultaneamente, integrem a Web 2.0 no processo de ensino e de aprendizagem no Ensino Básico, delineou-se a presente investigação. O estudo situa-se, assim, na interseção de dois campos: por um lado, as potencialidades do incentivo ao questionamento no processo pedagógico e, por outro, a integração educativa das TIC. A questão de Investigação que orientou este estudo foi a de avaliar de que forma é que o incentivo ao questionamento poderia contribuir para integrar o blogue de disciplina no trabalho em sala de aula de Ciências Naturais. Assim, concebemos, implementámos e avaliámos uma intervenção didática centrada na promoção da competência de questionamento, dando voz aos alunos, estimulando-os a formularem perguntas sobre os conteúdos, tanto presencialmente como no blogue da disciplina, denominado por “Mentes Curiosas”, utilizando essas perguntas como elementos integradores dos dois espaços. O estudo seguiu uma metodologia de investigação-ação e envolveu 36 alunos do 9.º ano de escolaridade, divididos em duas turmas, na disciplina de Ciências Naturais. Os instrumentos e métodos de recolha de dados foram diversificados, tendo todos os dados sido submetidos a uma análise de conteúdo. O estudo revela que os alunos utilizaram o blogue respondendo aos desafios colocados escrevendo comentários, respostas e, sobretudo, fazendo perguntas para as quais gostariam de obter respostas. O docente integrou essas perguntas na prática letiva dando continuidade às discussões de um ambiente para o outro, utilizando, desta forma, as perguntas dos alunos para a integração dos dois ambientes. A análise do questionamento registado revela que as perguntas online estão mais centradas nos conteúdos científicos e apresentam maior qualidade cognitiva quando comparadas com as formuladas em sala de aula. Por sua vez, no contexto presencial, as perguntas escritas são de maior nível de complexidade do que as perguntas orais. Através das diversas estratégias implementadas, quer para a promoção da capacidade de escrever perguntas, quer no trabalho realizado com o blogue, transformou-se a dinâmica do trabalho em sala de aula, melhorando-se o empenhamento dos alunos na aprendizagem. A estratégia de incentivo ao questionamento pelos alunos revelou-se, assim, como um fator que permite integrar de forma profícua o ambiente online no ambiente presencial neste nível de ensino. Por fim, a reflexão que fomos fazendo sobre as potencialidades do questionamento na relação professor-alunos-conteúdos, tanto no ambiente presencial como no virtual, levou-nos a perspetivar as perguntas segundo duas dimensões: Competência Cognitiva e Estratégia Didática. Enquanto Competência, o questionamento assume a função de ferramenta cognitiva e de regulador do processo de ensino e de aprendizagem. Enquanto Estratégia, a pergunta pode ser encarada como uma ferramenta didática na relação dialógica que se estabelece entre professor e alunos.

A moral, mural! : as ideias nos mapas e quadros parietais

Tese de doutoramento, Educação (História da Educação), Universidade de Lisboa, Instituto de Educação, 2014

Os textos de ciências na disciplina de PLNM : uma abordagem baseada em género

Tese de doutoramento, Linguística (Linguística Aplicada), Universidade de Lisboa, Faculdade de Letras, 2016

Compreensão de modelos didáticos pelos alunos do 5.º ano de escolaridade em ciências naturais

Relatório de Estágio apresentado à Escola Superior de Educação de Lisboa para obtenção de grau de mestre em Ensino do 1.º e 2.º Ciclo do Ensino Básico

The backwoods of our backyards : Ontario pioneers and the crisis of ecology /

Early in his landmark ecocritical book The Comedy of Survival, Joseph Meeker develops an intriguing hypothesis about human behaviour. He remarks the species Homo sapiens tend to behave like an invasive or pioneering organism, entering a bio-geographical region and aggressively outcompeting all other species for space and resources. Moreover, he suggests, human cultural traditions, at least in the West, have reinforced such behaviour, continually insisting that the impulses he describes are both necessary and right. While Meeker's work goes on to assess a number of literary works in both the tragic and comic modes, his work never fully explores this hypothesis in the context of human pioneers; that is, there is no ~xploration o( how these themes manifest themselves within our culture and what role they might play in the culture of specific pioneering groups. This project is an attempt at just such an analysis, examining the validity of Meeker's hypothesis through a case study of settler literature in Upper Canada/Ontario between the . years 1800-1867. It explores Meeker's work within three main areas: first, Chapter Two situates his book historically within the field of ecocriticism, showing what came before and the explosion of ecocritical inquiry that followed its release. This chapter also delves into the rift between the natural sciences and humanities, arguing that a move towards deeper interdisciplinarity is r:tecessary for the future. Chapter Three examines the biological and ecological ground on which Meeker rests his hypothesis through exploring evolutionary biology as well as invasive and pioneer species behaviour. Lastly, Chapter Four examines how these ecological principles are manifested in the writings of early Canadian settlers, suggesting that Meeker's hypothesis indeed finds itself on stable footing.

Husserl's approach to transcendental intersubjectivity

It is our intention in the course of the development of this thesis to give an account of how intersubjectivity is "eidetically" constituted by means of the application of the phenomenological reduction to our experience in the context of the thought of Edmund Husserl; contrasted with various representative thinkers in what H. Spiegelberg refers to as "the wider scene" of phenomenology. That is to say, we intend to show those structures of both consciousness and the relation which man has to the world which present themselves as the generic conditions for the possibility of overcoming our "radical sol itude" in order that we may gain access to the mental 1 ife of an Other as other human subject. It is clear that in order for us to give expression to these accounts in a coherent manner, along with their relative merits, it will be necessary to develop the common features of any phenomenological theory of consdousness whatever. Therefore, our preliminary inquiry, subordinate to the larger theme, shall be into some of the epistemological results of the application of the phenomenological method used to develop a transcendental theory of consciousness. Inherent in this will be the deliniation of the exigency for making this an lIintentional ll theory. We will then be able to see how itis possible to overcome transcendentally the Other as an object merely given among other merely given objects, and further, how this other is constituted specifically as other ego. The problem of transcendental intersubjectivity and its constitution in experience can be viewed as one of the most compelling, if not the most polemical of issues in phenomenology. To be sure, right from the beginning we are forced to ask a number of questions regarding Husserl's responses to the problem within the context of the methodological genesis of the Cartesian Meditations, and The Crisis of European Sciences and Transcendental Phenomenology. This we do in order to set the stage for amplification. First, we ask, has Husserl lived up to his goal, in this connexion, of an apodictic result? We recall that in his Logos article of 1911 he adminished that previous philosophy does not have at its disposal a merely incomplete and, in particular instances, imperfect doctrinal system; it simply has none whatever. Each and every question is herein controverted, each position is a matter of individual conviction, of the interpretation given byaschool, of a "point of view". 1. Moreover in the same article he writes that his goal is a philosophical system of doctrine that, after the gigantic preparatory work. of generations, really be- . gins from the ground up with a foundation free from doubt and rises up like any skilful construction, wherein stone is set upon store, each as solid as the other, in accord with directive insights. 2. Reflecting upon the fact that he foresaw "preparatory work of generations", we perhaps should not expect that he would claim that his was the last word on the matter of intersubjectivity. Indeed, with 2. 'Edmund Husserl, lIPhilosophy as a Rigorous Science" in Phenomenology and theCrisis6fPhilosophy, trans". with an introduction by Quentin Lauer (New York.: Harper & Row, 1965) pp. 74 .. 5. 2Ibid . pp. 75 .. 6. 3. the relatively small amount of published material by Husserl on the subject we can assume that he himself was not entirely satisfied with his solution. The second question we have is that if the transcendental reduction is to yield the generic and apodictic structures of the relationship of consciousness to its various possible objects, how far can we extend this particular constitutive synthetic function to intersubjectivity where the objects must of necessity always remain delitescent? To be sure, the type of 'object' here to be considered is unlike any other which might appear in the perceptual field. What kind of indubitable evidence will convince us that the characteristic which we label "alter-ego" and which we attribute to an object which appears to resemble another body which we have never, and can never see the whole of (namely, our own bodies), is nothing more than a cleverly contrived automaton? What;s the nature of this peculiar intentional function which enables us to say "you think just as I do"? If phenomenology is to take such great pains to reduce the takenfor- granted, lived, everyday world to an immanent world of pure presentation, we must ask the mode of presentation for transcendent sub .. jectivities. And in the end, we must ask if Husserl's argument is not reducible to a case (however special) of reasoning by analogy, and if so, tf this type of reasoning is not so removed from that from whtch the analogy is made that it would render all transcendental intersubjective understandtng impos'sible? 2. HistoticalandEidetic Priority: The Necessity of Abstraction 4. The problem is not a simple one. What is being sought are the conditions for the poss ibili:ty of experi encing other subjects. More precisely, the question of the possibility of intersubjectivity is the question of the essence of intersubjectivity. What we are seeking is the absolute route from one solitude to another. Inherent in this programme is the ultimate discovery of the meaning of community. That this route needs be lIabstract" requires some explanation. It requires little explanation that we agree with Husserl in the aim of fixing the goal of philosophy on apodictic, unquestionable results. This means that we seek a philosophical approach which is, though, not necessarily free from assumptions, one which examines and makes explicit all assumptions in a thorough manner. It would be helpful at this point to distinguish between lIeidetic ll priority, and JlhistoricallJpriority in order to shed some light on the value, in this context, of an abstraction.3 It is true that intersubjectivity is mundanely an accomplished fact, there havi.ng been so many mi.llions of years for humans to beIt eve in the exi s tence of one another I s abili ty to think as they do. But what we seek is not to study how this proceeded historically, but 3Cf• Maurice Natanson;·TheJburne in 'Self, a Stud in Philoso h and Social Role (Santa Cruz, U. of California Press, 1970 . rather the logical, nay, "psychological" conditions under which this is possible at all. It is therefore irrelevant to the exigesis of this monograph whether or not anyone should shrug his shoulders and mumble IIwhy worry about it, it is always already engaged". By way of an explanation of the value of logical priority, we can find an analogy in the case of language. Certainly the language 5. in a spoken or written form predates the formulation of the appropriate grammar. However, this grammar has a logical priority insofar as it lays out the conditions from which that language exhibits coherence. The act of formulating the grammar is a case of abstraction. The abstraction towards the discovery of the conditions for the poss; bi 1 ity of any experiencing whatever, for which intersubjective experience is a definite case, manifests itself as a sort of "grammar". This "grammar" is like the basic grammar of a language in the sense that these "rulesil are the ~ priori conditions for the possibility of that experience. There is, we shall say, an "eidetic priority", or a generic condition which is the logical antecedent to the taken-forgranted object of experience. In the case of intersubjectivity we readily grant that one may mundanely be aware of fellow-men as fellowmen, but in order to discover how that awareness is possible it is necessary to abstract from the mundane, believed-in experience. This process of abstraction is the paramount issue; the first step, in the search for an apodictic basis for social relations. How then is this abstraction to be accomplished? What is the nature of an abstraction which would permit us an Archimedean point, absolutely grounded, from which we may proceed? The answer can be discovered in an examination of Descartes in the light of Husserl's criticism. 3. The Impulse for Scientific Philosophy. The Method to which it Gives Rise. 6. Foremost in our inquiry is the discovery of a method appropriate to the discovery of our grounding point. For the purposes of our investigations, i.e., that of attempting to give a phenomenological view of the problem of intersubjectivity, it would appear to be of cardinal importance to trace the attempt of philosophy predating Husserl, particularly in the philosophy of Descartes, at founding a truly IIscientific ll philosophy. Paramount in this connexion would be the impulse in the Modern period, as the result of more or less recent discoveries in the natural sciences, to found philosophy upon scientific and mathematical principles. This impulse was intended to culminate in an all-encompassing knowledge which might extend to every realm of possible thought, viz., the universal science ot IIMathexis Universalis ll •4 This was a central issue for Descartes, whose conception of a universal science would include all the possible sciences of man. This inclination towards a science upon which all other sciences might be based waS not to be belittled by Husserl, who would appropriate 4This term, according to Jacab Klein, was first used by Barocius, the translator of Proclus into Latin, to designate the highest mathematical discipline. . 7. it himself in hopes of establishing, for the very first time, philosophy as a "rigorous science". It bears emphasizing that this in fact was the drive for the hardening of the foundations of philosophy, the link between the philosophical projects of Husserl and those of the philosophers of the modern period. Indeed, Husserl owes Descartes quite a debt for indicating the starting place from which to attempt a radical, presupositionless, and therefore scientific philosophy, in order not to begin philosophy anew, but rather for the first time.5 The aim of philosophy for Husserl is the search for apodictic, radical certitude. However while he attempted to locate in experience the type of necessity which is found in mathematics, he wished this necessity to be a function of our life in the world, as opposed to the definition and postulation of an axiomatic method as might be found in the unexpurgated attempts to found philosophy in Descartes. Beyond the necessity which is involved in experiencing the world, Husserl was searching for the certainty of roots, of the conditi'ons which underl ie experience and render it pOssible. Descartes believed that hi~ MeditatiOns had uncovered an absolute ground for knowledge, one founded upon the ineluctable givenness of thinking which is present even when one doubts thinking. Husserl, in acknowledging this procedure is certainly Cartesian, but moves, despite this debt to Descartes, far beyond Cartesian philosophy i.n his phenomenology (and in many respects, closer to home). 5Cf. Husserl, Philosophy as a Rigorous Science, pp. 74ff. 8 But wherein lies this Cartesian jumping off point by which we may vivify our theme? Descartes, through inner reflection, saw that all of his convictions and beliefs about the world were coloured in one way or another by prejudice: ... at the end I feel constrained to reply that there is nothing in a all that I formerly believed to be true, of which I cannot in some measure doubt, and that not merely through want of thought or through levity, but for reasons which are very powerful and maturely considered; so that henceforth I ought not the less carefully to refrain from giving credence to these opinions than to that which is manifestly false, if I desire to arrive at any certainty (in the sciences). 6 Doubts arise regardless of the nature of belief - one can never completely believe what one believes. Therefore, in order to establish absolutely grounded knowledge, which may serve as the basis fora "universal Science", one must use a method by which one may purge oneself of all doubts and thereby gain some radically indubitable insight into knowledge. Such a method, gescartes found, was that, as indicated above by hi,s own words, of II radical doubt" which "forbids in advance any judgemental use of (previous convictions and) which forbids taking any position with regard to their val idi'ty. ,,7 This is the method of the "sceptical epoche ll , the method of doubting all which had heretofor 6Descartes,Meditations on First Philosophy, first Med., (Libera 1 Arts Press, New York, 1954) trans. by L. LaFl eur. pp. 10. 7Husserl ,CrisiS of Eliroeari SCiences and Trariscendental Phenomenology, (Northwestern U. Press, Evanston, 1 7 ,p. 76. 9. been considered as belonging to the world, including the world itself. What then is left over? Via the process of a thorough and all-inclusive doubting, Descartes discovers that the ego which performs the epoche, or "reduction", is excluded from these things which can be doubted, and, in principle provides something which is beyond doubt. Consequently this ego provides an absolute and apodictic starting point for founding scientific philosophy. By way of this abstention. of bel ief, Desca'rtes managed to reduce the worl d of everyday 1 ife as bel ieved in, to mere 'phenomena', components of the rescogitans:. Thus:, having discovered his Archimedean point, the existence of the ego without question, he proceeds to deduce the 'rest' of the world with the aid of innate ideas and the veracity of God. In both Husserl and Descartes the compelling problem is that of establ ishing a scientific, apodictic phi'losophy based upon presuppos itionless groundwork .. Husserl, in thi.s regard, levels the charge at Descartes that the engagement of his method was not complete, such that hi.S: starting place was not indeed presupositionless, and that the validity of both causality and deductive methods were not called into question i.'n the performance of theepoche. In this way it is easy for an absolute evidence to make sure of the ego as: a first, "absolute, indubitablyexisting tag~end of the worldll , and it is then only a matter of inferring the absolute subs.tance and the other substances which belon.g to the world, along with my own mental substance, using a logically val i d deductive procedure. 8 8Husserl, E.;' Cartesian 'Meditation;, trans. Dorion Cairns (Martinus Nijhoff, The Hague, 1970), p. 24 ff.

The falls of Niagara and their retrograde movement /

"From the proceedings of the Academy of Natural Sciences of Newchatel, 1854."

Perceptions of Adolescent Males and Their Parents as to Factors That Influence the Young Men's Academic Performance

Postsecondary enrolments of young males has been declining since the mid-1980s. The decline can be attributed, at least in part, to boys and young men being unable to compete for a fixed number of available places in institutions of higher learning, whether in community college or university. This inability to compete stems from their academic performance in secondary school. This study interviewed adolescent males and their parents as to their perceptions of a number of factors that may contribute to their academic performance. Those factors included noncognitive skills, dimensions of character, perceptions of teachers, general attitudes towards school, and likes and dislikes on a range of course subjects. One of the most important findings was that only one of the seven adolescent male participants was considering a future career that would require a university degree. Other findings showed the young men's noncognitive skills were weak, particularly in relation to time management skills and their unwillingness to ask for help with schoolwork and homework. Most of the young men expressed a dislike for mathematics beyond high school, a subject key to the study, of the natural sciences, engineering, technology, and business. Recommendations include school reforms both inside the classroom and beyond. Additionally, a framework using project management theory and practice has been proposed to improve noncognitive skills, dimensions of character, and executive function.

Variability in the Insect and Plant Adhesins, Mad1 and Mad2, within the Fungal Genus Metarhizium Suggest Plant Adaptation as an Evolutionary Force

Several species of the insect pathogenic fungus Metarhizium are associated with certain plant types and genome analyses suggested a bifunctional lifestyle; as an insect pathogen and as a plant symbiont. Here we wanted to explore whether there was more variation in genes devoted to plant association (Mad2) or to insect association (Mad1) overall in the genus Metarhizium. Greater divergence within the genus Metarhizium in one of these genes may provide evidence for whether host insect or plant is a driving force in adaptation and evolution in the genus Metarhizium. We compared differences in variation in the insect adhesin gene, Mad1, which enables attachment to insect cuticle, and the plant adhesin gene, Mad2, which enables attachment to plants. Overall variation for the Mad1 promoter region (7.1%), Mad1 open reading frame (6.7%), and Mad2 open reading frame (7.4%) were similar, while it was higher in the Mad2 promoter region (9.9%). Analysis of the transcriptional elements within the Mad2 promoter region revealed variable STRE, PDS, degenerative TATA box, and TATA box-like regions, while this level of variation was not found for Mad1. Sequences were also phylogenetically compared to EF-1a, which is used for species identification, in 14 isolates representing 7 different species in the genus Metarhizium. Phylogenetic analysis demonstrated that the Mad2 phylogeny is more congruent with 59 EF-1a than Mad1. This would suggest that Mad2 has diverged among Metarhizium lineages, contributing to clade- and species-specific variation, while it appears that Mad1 has been largely conserved. While other abiotic and biotic factors cannot be excluded in contributing to divergence, these results suggest that plant relationships, rather than insect host, have been a major driving factor in the divergence of the genus Metarhizium.

Natural air conditioning, traditions and trends : high performance of sustainable indoor ventilation in a hot and dry climate

De nos jours, l'utilisation accrue de combustibles à base de fossiles et l'électricité met en péril l'environnement naturel à cause des niveaux élevés de pollution. Il est donc plausible de prévoir des économies d'énergie significatives grâce à la climatisation dite «naturelle»». En accord avec les objectifs acceptés à l'échelle internationale d'une architecture «verte» et durable, l'utilisation de cours intérieures associées aux capteurs de vent, aux murs-Trombe et à d'autres systèmes de climatisation naturelle (aussi bien traditionnels que nouveaux), paraît prometteuse. Ce mémoire propose une analyse de nouvelles approches à la climatisation naturelle et à la production d'air frais avec une consommation minimale d'énergie, eu égard aux traditions et aux tendances, en particulier dans les zones climatiques chaudes et sèches comme l'Iran. Dans ce contexte, regarder l'architecture de l'Islam et la discipline du Qur'an paraissent offrir un guide pour comprendre l'approche musulmane aux processus de décision en design. Nous regardons donc les traditions et les tendances en ce qui concerne la climatisation naturelle à travers l'élément le plus important du contexte islamique, à savoir le Qur'an. C'est pourquoi, à l'intérieur du thème de la tradition, nous avons pris en compte quelques considérations concernant l'influence de l'Islam, et en particulier le respect de la nature associé à un équilibre entre l'harmonie et l'individualité. Ce sont autant de facteurs qui influencent la prise de décisions visant à résoudre des problèmes scientifiques majeurs selon la philosophie et les méthodes islamiques ; ils nous permettent de faire quelques recommandations. La description des principes sous-jacents aux capteurs à vent et des antécédents trouvés dans la nature tels que les colonies de termites, est présentée également. Sous la rubrique tendances, nous avons introduit l'utilisation de matériaux et de principes de design nouveaux. Regarder simultanément ces matériaux nouveaux et l'analogie des colonies de termites suggère de bonnes approches à la conception d'abris pour les victimes de tremblements de terre dans les régions sisimques. Bam, une ville iranienne, peut être considérée comme un exemple spécifique illustrant où les principes exposés dans ce mémoire peuvent s'appliquer le plus adéquatement.

Immobilization of Diastase α-amylase on to synthetic and natural polymers

Several natural and synthetic supports have been assessed for their efficiency for enzyme immobilization. Synthetic polymer materials are prepared by chemical polymerization using various monomers. As a kind of important carrier, synthetic polymer materials exhibit the advantages of good mechanical rigidity, high specific surface area, inertness to microbial attack, easy to change their surface characteristics, and their potential for bringing specific functional group according to actual needs. Hence, they have been widely investigated and used for enzyme immobilization. When it comes to the natural polymer materials, much attention has been paid to cellulose and other natural polymer materials owing to their wide range of sources, easy modification, nontoxic, and pollution-free, with a possibility of introducing wide variety of functional groups and good biocompatible properties. In this work report the use of synthetic polymer, polypyrrole and its derivatives and natural polymers coconut fiber and sugarcane bagasse as supports for Diastase α- amylase immobilization. An attempt was also made to functionalize both synthetic and natural polymers using Amino-propyl triethoxysilane. Supports and their immobilized forms were characterized via FT-IR, TG, SEM, XRD, BET and EDS techniques. Immobilization parameters were also optimized so as to prepare stable immobilized biocatalyst for starch hydrolysis.

HelF, a suppressor of RNAi mediated gene silencing in Dictyostelium discoideum

RNA interference (RNAi) is a recently discovered process, in which double stranded RNA (dsRNA) triggers the homology-dependant degradation of cognate messenger RNA (mRNA). In a search for new components of the RNAi machinery in Dictyostelium, a new gene was identified, which was called helF. HelF is a putative RNA helicase, which shows a high homology to the helicase domain of Dicer, to the helicase domain of Dictyostelium RdRP and to the C. elegans gene drh-1, that codes for a dicer related DExH-box RNA helicase, which is required for RNAi. The aim of the present Ph.D. work was to investigate the role of HelF in PTGS, either induced by RNAi or asRNA. A genomic disruption of the helF gene was performed, which resulted in a distinct mutant morphology in late development. The cellular localization of the protein was elucidated by creating a HelF-GFP fusion protein, which was found to be localized in speckles in the nucleus. The involvement of HelF in the RNAi mechanism was studied. For this purpose, RNAi was induced by transformation of RNAi hairpin constructs against four endogenous genes in wild type and HelF- cells. The silencing efficiency was strongly enhanced in the HelF K.O. strain in comparison with the wild type. One gene, which could not be silenced in the wild type background, was successfully silenced in HelF-. When the helF gene was disrupted in a secondary transformation in a non-silenced strain, the silencing efficiency was strongly improved, a phenomenon named here “retrosilencing”. Transcriptional run-on experiments revealed that the enhanced gene silencing in HelF- was a posttranscriptional event, and that the silencing efficiency depended on the transcription levels of hairpin RNAs. In HelF-, the threshold level of hairpin transcription required for efficient silencing was dramatically lowered. The RNAi-mediated silencing was accompanied by the production of siRNAs; however, their amount did not depend on the level of hairpin transcription. These results indicated that HelF is a natural suppressor of RNAi in Dictyostelium. In contrast, asRNA mediated gene silencing was not enhanced in the HelF K.O, as shown for three tested genes. These results confirmed previous observations (H. Martens and W. Nellen, unpublished) that although similar, RNAi and asRNA mediated gene silencing mechanisms differ in their requirements for specific proteins. In order to characterize the function of the HelF protein on a molecular level and to study its interactions with other RNAi components, in vitro experiments were performed. Besides the DEAH-helicase domain, HelF contains a double-stranded RNA binding domain (dsRBD) at its N-terminus, which showed high similarity to the dsRBD domain of Dicer A from Dictyostelium. The ability of the recombinant dsRBDs from HelF and Dicer A to bind dsRNA was examined and compared. It was shown by gel-shift assays that both HelF-dsRBD and Dicer-dsRBD could bind directly to long dsRNAs. However, HelF-dsRBD bound more efficiently to dsRNA with imperfect matches than to perfect dsRNA. Both dsRBDs bound specifically to a pre-miRNA substrate (pre-let-7). The results suggested that most probably there were two binding sites for the proteins on the pre-miRNA substrate. Moreover, it was shown that HelF-dsRBD and Dicer-dsRBD have siRNA-binding activity. The affinities of the two dsRBDs to the pre-let-7 substrate were also examined by plasmon surface resonance analyses, which revealed a 9-fold higher binding affinity of the Dicer-dsRBD to pre-let-7 compared to that of the HelF-dsRBD. The binding of HelF-dsRBD to the pre-let-7 was impaired in the presence of Mg2+, while the Dicer-dsRBD interaction with pre-let-7 was not influenced by the presence of Mg2+. The results obtained in this thesis can be used to postulate a model for HelF function. In this, HelF acts as a nuclear suppressor of RNAi in wild type cells by recognition and binding of dsRNA substrates. The protein might act as a surveillance system to avoid RNAi initiation by fortuitous dsRNA formation or low abundance of dsRNA trigger. If the protein acts as an RNA helicase, it could unwind fold-back structures in the nucleus and thus lead to decreased RNAi efficiency. A knock-out of HelF would result in initiation of the RNAi pathway even by low levels of dsRNA. The exact molecular function of the protein in the RNAi mechanism still has to be elucidated. RNA interferenz (RNAi) ist ein in jüngster Zeit entdeckter Mechanismus, bei dem doppelsträngige RNA Moleküle (dsRNA) eine Homologie-abhängige Degradation einer verwandten messenger-RNA (mRNA) auslösen. Auf der Suche nach neuen Komponenten der RNAi-Maschinerie in Dictyostelium konnte ein neues Gen (helF) identifiziert werden. HelF ist eine putative RNA-Helikase mit einer hohen Homologie zur Helikasedomäne der bekannten Dicerproteine, der Helikasedomäne der Dictyostelium RdRP und zu dem C. elegans Gen drh-1, welches für eine Dicer-bezogene DExH-box RNA Helikase codiert, die am RNAi-Mechanismus beteiligt ist. Das Ziel dieser Arbeit war es, die Funktion von HelF im Zusammenhang des RNAi oder asRNA induzierten PTGS zu untersuchen. Es wurde eine Unterbrechung des helF-Gens auf genomischer Ebene (K.O.) vorgenommen, was bei den Mutanten zu einer veränderten Morphologie in der späten Entwicklung führte. Die Lokalisation des Proteins in der Zelle konnte mit Hilfe einer GFP-Fusion analysiert werden und kleinen Bereichen innerhalb des Nukleus zugewiesen werden. Im Weiteren wurde der Einfluss von HelF auf den RNAi-Mechanismus untersucht. Zu diesem Zweck wurde RNAi durch Einbringen von RNAi Hairpin-Konstrukten gegen vier endogene Gene im Wiltypstamm und der HelF--Mutante induziert. Im Vergleich zum Wildtypstamm konnte im HelF--Mutantenstamm eine stark erhöhte „Silencing“-Effizienz nachgewiesen werden. Ein Gen, welches nach RNAi Initiation im Wildtypstamm unverändert blieb, konnte im HelF--Mutantenstamm erfolgreich stillgelegt werden. Durch sekundäres Einführen einer Gendisruption im helF-Locus in einen Stamm, in welchem ein Gen nicht stillgelegt werden konnte, wurde die Effizienz des Stilllegens deutlich erhöht. Dieses Phänomen wurde hier erstmals als „Retrosilencing“ beschrieben. Mit Hilfe von transkriptionellen run-on Experimenten konnte belegt werden, dass es sich bei dieser erhöhten Stilllegungseffizienz um ein posttranskriptionelles Ereignis handelte, wobei die Stillegungseffizienz von der Transkriptionsstärke der Hairpin RNAs abhängt. Für die HelF--Mutanten konnte gezeigt werden, dass der Schwellenwert zum Auslösen eines effizienten Stillegens dramatisch abgesenkt war. Obwohl die RNAi-vermittelte Genstilllegung immer mit der Produktion von siRNAs einhergeht, war die Menge der siRNAs nicht abhängig von dem Expressionsniveau des Hairpin-Konstruktes. Diese Ergebnisse legen nahe, dass es sich bei der HelF um einen natürlichen Suppressor des RNAi-Mechanismus in Dictyostelium handelt. Im Gegensatz hierzu war die as-vermittelte Stilllegung von drei untersuchten Genen im HelF-K.O. im Vergleich zum Wildyp unverändert. Diese Ergebnisse bestätigten frühere Beobachtungen (H. Martens und W. Nellen, unveröffentlicht), wonach die Mechanismen für RNAi und asRNA-vermittelte Genstilllegung unterschiedliche spezifische Proteine benötigen. Um die Funktion des HelF-Proteins auf der molekularen Ebene genauer zu charakterisieren und die Interaktion mit anderen RNAi-Komponenten zu untersuchen, wurden in vitro Versuche durchgeführt. Das HelF-Protein enthält, neben der DEAH-Helikase-Domäne eine N-terminale Doppelstrang RNA bindende Domäne (dsRBD) mit einer hohen Ähnlichkeit zu der dsRBD des Dicer A aus Dictyostelium. Die dsRNA-Bindungsaktivität der beiden dsRBDs aus HelF und Dicer A wurde analysiert und verglichen. Es konnte mithilfe von Gel-Retardationsanalysen gezeigt werden, dass sowohl HelF-dsRBD als auch Dicer-dsRBD direkt an lange dsRNAs binden können. Hierbei zeigte sich, dass die HelF-dsRBD eine höhere Affinität zu einem imperfekten RNA-Doppelstrang besitzt, als zu einer perfekt gepaarten dsRNA. Für beide dsRBDs konnte eine spezifische Bindung an ein pre-miRNA Substrat nachgewiesen werden (pre-let-7). Dieses Ergebnis legt nah, dass es zwei Bindestellen für die Proteine auf dem pre-miRNA Substrat gibt. Überdies hinaus konnte gezeigt werden, dass die dsRBDs beider Proteine eine siRNA bindende Aktivität besitzen. Die Affinität beider dsRBDs an das pre-let-7 Substrat wurde weiterhin mit Hilfe der Plasmon Oberflächen Resonanz untersucht. Hierbei konnte eine 9-fach höhere Bindeaffinität der Dicer-dsRBD im Vergleich zur HelF-dsRBD nachgewiesen werden. Während die Bindung der HelF-dsRBD an das pre-let-7 durch die Anwesenheit von Mg2+ beeinträchtigt war, zeigte sich kein Einfluß von Mg2+ auf das Bindeverhalten der Dicer-dsRBD. Mit Hilfe der in dieser Arbeit gewonnen Ergebnisse lässt sich ein Model für die Funktion von HelF postulieren. In diesem Model wirkt HelF durch Erkennen und Binden von dsRNA Substraten als Suppressor von der RNAi im Kern. Das Protein kann als Überwachungsystem gegen eine irrtümliche Auslösung von RNAi wirken, die durch zufällige dsRNA Faltungen oder eine zu geringe Häufigkeit der siRNAs hervorgerufen sein könnte. Falls das Protein eine Helikase-Aktivität besitzt, könnte es rückgefaltete RNA Strukturen im Kern auflösen, was sich in einer verringerten RNAi-Effizienz wiederspiegelt. Durch Ausschalten des helF-Gens würde nach diesem Modell eine erfolgreiche Auslösung von RNAi schon bei sehr geringer Mengen an dsRNA möglich werden. Das Modell erlaubt, die exakte molekulare Funktion des HelF-Proteins im RNAi-Mechanismus weiter zu untersuchen.

VUV-Laserablation von Spinnenseide

Spinnenseide gehört zu den stabilsten bekannten Polymerverbindungen. Spinnfäden können bis auf das Dreifache ihrer ursprünglichen Länge gedehnt werden, bevor sie reißen, und dabei mit rund 160 MJ/m³ mehr als dreimal soviel Energie absorbieren wie die stärkste synthetisch hergestellte Faser Kevlar (50 MJ/m³). Dabei weisen Spinnfäden mit 2 bis 5 Mikrometer nur ein Zehntel des Durchmessers eines menschlichen Haares auf. Das präzise, berührungslose Bearbeiten von Spinnenseide ist für verschiedene technische Anwendungen interessant, insbesondere wenn dabei ihre außergewöhnlichen Eigenschaften erhalten bleiben. Könnten die von Natur aus dünnen Seidenfäden gezielt in ihrem Durchmesser verringert werden, so wären sie unter anderem in der Mikroelektronik einzusetzen. Hier könnten sie als Trägermaterial für eine dünne, elektrisch leitfähige Schicht fungieren. Man erhielte Nanodrähte, die auch in mechanisch besonders belasteten Mikroelektronikbauteilen (MEMS) Verwendung finden könnten. In dieser Arbeit wird die Verwendung der laserinduzierten Ablation zur gezielten Bearbeitung von Haltefäden der Schwarzen Witwe (Latrodectus hesperus) beschrieben. Eingesetzt wurde ein VUV-Excimerlaser vom Typ LPF 205 (Lambda-Physik, Göttingen) mit einer Wellenlänge von 157 nm und einer Pulsdauer von 18 ns. Eine berührungslose Laserbearbeitung bei 157 nm erlaubt einen effizienten und präzisen Abtrag von Material durch Ablation aufgrund der geringen optischen Eindringtiefe von unter 100 nm oberhalb einer Schwellenfluenz (Energie/Fläche) von Φth=29 mJ/cm², ohne dabei das umgebende Material thermisch zu beeinträchtigen. Parallel zur Ablation setzt allerdings eine wellenförmige Oberflächenstrukturierung auf der Faseroberfläche ein, wodurch die mechanische Belastbarkeit der Faser entscheidend geschwächt wird. Die Ursache hierfür liegt im Abbau materialbedingter Spannungsfelder („stress release“) innerhalb einer durch das Laserlicht induzierten dünnen Schmelzschicht. Im Rahmen dieser Arbeit ist es nun gelungen, diese Strukturen durch einen anschließenden Glättungsprozeß zu entfernen. Dabei wird auf der bestrahlten Oberfläche mittels Laserlichts eine glatte Ablation erzielt. Mit feinerer Abstufung dieser Prozeßschritte konnte der Durchmesser des verwendeten Spinnenseidefadens zum Teil um 70 Prozent bis auf ca. 750 nm verringert werden. Durch Zugfestigkeitsexperimente wurde belegt, daß die mechanischen Eigenschaften der so bearbeiteten Spinnenseide weitgehend erhalten bleiben. Die im Rahmen dieser Arbeit angewandte Methode erlaubt somit eine präzise Laserablation von Spinnenseide und ähnlichen hochabsorbierenden Materialien, ohne deren Kernsubstanz in ihrer Beschaffenheit zu verändern.