978 resultados para Lawrence
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Heterozygous germline mutations in the zinc finger transcription factor GATA2 have recently been shown to underlie a range of clinical phenotypes, including Emberger syndrome, a disorder characterized by lymphedema and predisposition to myelodysplastic syndrome/acute myeloid leukemia (MDS/AML). Despite well-defined roles in hematopoiesis, the functions of GATA2 in the lymphatic vasculature and the mechanisms by which GATA2 mutations result in lymphedema have not been characterized. Here, we have provided a molecular explanation for lymphedema predisposition in a subset of patients with germline GATA2 mutations. Specifically, we demonstrated that Emberger-associated GATA2 missense mutations result in complete loss of GATA2 function, with respect to the capacity to regulate the transcription of genes that are important for lymphatic vessel valve development. We identified a putative enhancer element upstream of the key lymphatic transcriptional regulator PROX1 that is bound by GATA2, and the transcription factors FOXC2 and NFATC1. Emberger GATA2 missense mutants had a profoundly reduced capacity to bind this element. Conditional Gata2 deletion in mice revealed that GATA2 is required for both development and maintenance of lymphovenous and lymphatic vessel valves. Together, our data unveil essential roles for GATA2 in the lymphatic vasculature and explain why a select catalogue of human GATA2 mutations results in lymphedema.
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Freshwater species worldwide are experiencing dramatic declines partly attributable to ongoing climate change. It is expected that the future effects of climate change could be particularly severe in mediterranean climate (med-) regions, which host many endemic species already under great stress from the high level of human development. In this article, we review the climate and climate-induced changes in streams of med-regions and the responses of stream biota, focusing on both observed and anticipated ecological responses. We also discuss current knowledge gaps and conservation challenges. Expected climate alterations have already been observed in the last decades, and include: increased annual average air temperatures; decreased annual average precipitation; hydrologic alterations; and an increase in frequency, intensity and duration of extreme events, such as floods, droughts and fires. Recent observations, which are concordant with forecasts built, show stream biota of med-regions when facing climate changes tend to be displaced towards higher elevations and upper latitudes, communities tend to change their composition and homogenize, while some life-history traits seem to provide biota with resilience and resistance to adapt to the new conditions (as being short-lived, small, and resistant to low streamflow and desiccation). Nevertheless, such responses may be insufficient to cope with current and future environmental changes. Accurate forecasts of biotic changes and possible adaptations are difficult to obtain in med-regions mainly because of the difficulty of distinguishing disturbances due to natural variability from the effects of climate change, particularly regarding hydrology. Long-term studies are needed to disentangle such variability and improve knowledge regarding the ecological responses and the detection of early warning signals to climate change. Investments should focus on taxa beyond fish and macroinvertebrates, and in covering the less studied regions of Chile and South Africa. Scientists, policy makers and water managers must be involved in the climate change dialogue because the freshwater conservation concerns are huge.
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The preparation of [FeIV(O)(MePy2tacn)]2+ (2, MePy2tacn = N-methyl-N,N-bis(2-picolyl)-1,4,7-triazacyclononane) by reaction of [FeII(MePy2tacn)(solvent)]2+ (1) and PhIO in CH3CN and its full characterization are described. This compound can also be prepared photochemically from its iron(II) precursor by irradiation at 447 nm in the presence of catalytic amounts of [Ru II(bpy)3]2+ as photosensitizer and a sacrificial electron acceptor (Na2S2O8). Remarkably, the rate of the reaction of the photochemically prepared compound 2 toward sulfides increases 150-fold under irradiation, and 2 is partially regenerated after the sulfide has been consumed; hence, the process can be repeated several times. The origin of this rate enhancement has been established by studying the reaction of chemically generated compound 2 with sulfides under different conditions, which demonstrated that both light and [Ru II(bpy)3]2+ are necessary for the observed increase in the reaction rate. A combination of nanosecond time-resolved absorption spectroscopy with laser pulse excitation and other mechanistic studies has led to the conclusion that an electron transfer mechanism is the most plausible explanation for the observed rate enhancement. According to this mechanism, the in-situ-generated [RuIII(bpy)3] 3+ oxidizes the sulfide to form the corresponding radical cation, which is eventually oxidized by 2 to the corresponding sulfoxide
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Kirjallisuusarvostelu
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The element silicon (Si) is not considered an essential nutrient for plant function. Nevertheless, Si is absorbed from soil in large amounts that are several fold higher than those of other essential macronutrients in certain plant species. Its beneficial effects have been reported in various situations, especially under biotic and abiotic stress conditions. The most significant effect of Si on plants, besides improving their fitness in nature and increasing agricultural productivity, is the restriction of parasitism. There has been a considerable amount of research showing the positive effect of Si in controlling diseases in important crops. Rice (Oryza sativa), in particular, is affected by the presence of Si, with diseases such as blast, brown spot and sheath blight becoming more severe on rice plants grown in Si-depleted soils. The hypothesis underlying the control of some diseases in both mono- and di-cots by Si has been confined to that of a mechanical barrier resulting from its polymerization in planta. However, some studies show that Si-mediated resistance against pathogens is associated with the accumulation of phenolics and phytoalexins as well as with the activation of some PR-genes. These findings strongly suggest that Si plays an active role in the resistance of some plants to diseases rather than forming a physical barrier that impedes penetration by fungal pathogens.
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This research is a phenomenological-hermeneutic case-study based on the methods of action research in which narrative methods are used to examine a process drama carried out in a day-care centre, focusing on its dialogicality and possibilities of offering children and adults ethical problems to examine and solve. A process drama built around a story was carried out in a Finnish day-care centre in 1999 with the aim of bringing ethical education to the level of conscious consideration and action. The research consists of two case-studies. The first focuses on Risto, one of the children who participated in the process, his actions in group situations, his commitment to the rules set by the leaders, his attitude towards the group and its members as well as the common agreements concerning the group, and his solutions to fictive dilemmas in relation to Lawrence Kohlberg’s and Carol Gilligan’s concepts of justice and care. On this basis conclusions are made on how drama can be applied to dealing with ethical dilemmas with children aged four to seven. The second case-study searches for ethical themes and signs of dialogicality in the story that was created together by the children and leaders, and in the action that took place in the drama sessions. The subjects of this study consist of two groups participating in the process drama, both consisting of seven children aged four to seven. Narratives were written on each child based on his/her participation in four drama sessions selected to be used in this study. The narratives include the writer’s interpretations of the dialogicality of the drama and the ethical themes observed and recognised in the videos and in the transcriptions of the video recordings. The description and interpretation of the dialogicality and the ethical themes observed in the drama sessions is based on the researcher’s dialogue with the writings of Georg Henrik von Wright, Martin Buber and Mihail Bahtin, as well as Nicholas C. Burbules’ definitions of the basic conditions for dialogical teaching. As a result of the study, drama activity proved to be a means by which dialogically abstract ethical questions and conflicts could be dealt with even with young children and which revealed the zone of proximal development of both children and adults. Drama became a stage for ethical growth and dialogicality, and the common play of children and adults could be seen as an indicator of deep dialogicality. On the basis of this study, it can be said that drama is a very suitable way of establishing a shape and form of ethical education in which it is possible to make planned, target-oriented progress and which can be consciously observed by following the development of both the child and the educator.
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Kirjallisuusarvostelu
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The authors report a case of an one-year-old girl with growth retardation, vomiting, aspiration pneumonias and malnutrition presenting gastroesopheal reflux and microgastria. The child was underwent a double lumen Roux-en-Y jejunal reservoir (Hunt-Lawrence pouch). This treatment improved nutritional status and growth. No others anomalies were detected. Congenital microgastria is a rare anomaly which is usually associated with other malformations. The authors reviewed the literature and recommend the gastric augmentation for the treatment for microgastria.
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Pro gradu -tutkielmani tavoitteena on analysoida ympäristön merkityksiä yhdysvaltalaiskirjailija Don DeLillon (1936-) romaanissa White Noise (1985). Lähestyn romaania ekokriittisen kirjallisuudentutkimuksen näkökulmasta ja kytken sen ekokriitikko Lawrence Buellin ajatukseen nk. ympäristöalitajunnasta. Analysoin DeLillon romaania myös yhteydessä filosofi Jean Baudrillardin ajatukseen postmodernin ajan länsimaisessa ja erityisesti amerikkalaisessa yhteiskunnassa vallalla olevasta simulaatioiden järjestelmästä. White Noise -romaanin todellisuus vastaa Baudrillardin ajatusta yhteiskunnasta, jossa representaatiot ja simulaatiot ovat korvanneet todellisuuden. Media, erityisesti televisio, tuottaa jatkuvasti kuvia ja simulaatioita, joiden kyllästämässä todellisuudessa aineellinen maailma ja luonto jäävät tavoittamattomiin. White Noise -romaanin henkilöiden yhteys aineelliseen ympäristöönsä ja luonnonilmiöihin on katkennut, sillä heidän arkensa pyörii pitkälti kuluttamisen ja televisionkatselun ympärillä. Romaanin todellisuudessa myös identiteetistä on tullut eräänlainen tuote, jonka jokainen voi rakentaa mieleisekseen kulutusvalinnoillaan. Identiteettiproblematiikan ohella myös kuolemalla on keskeinen asema tutkielmassani. White Noise -romaanin päähenkilö Jack Gladney kärsii paniikinomaisesta kuolemanpelosta, jota pyrkii torjumaan erilaisin keinoin siinä kuitenkaan onnistumatta. Tavoitteenani on osoittaa, että tämä piinaava pelko kuolemaa kohtaan on syntynyt simulaatioyhteiskunnan tuloksena. Vieraantuminen aineellisesta maailmasta ja luonnon prosesseista on johtanut vieraantumiseen ruumiista ja kuolemasta. Analysoin kuolemaa romaanissa eräänlaisena simulaatioiden maailman äärirajana, viimeisenä luonnollisena tapahtumana. White Noise -romaanin päähenkilö Jack Gladney ahdistuu kulutuskeskeisessä, simulaatioiden kyllästämässä elinympäristössään. Tulkitsen tämän ahdistuksen tarpeena tunnistaa tärkeä vuorovaikutussuhde yksilön ja hänen aineellisen ympäristönsä välillä. Jack ei ole vielä täysin sulautunut osaksi simulaatioiden maailmaa, vaan hän tiedostaa kytköksen itsensä ja aineellisen maailman välillä. Tämä romaanista implisiittisesti esiin nouseva tiedostamisen tunne korostaa ihmisen ja ympäristön sekä laajemmin kulttuurin ja luonnon välttämätöntä yhteyttä. DeLillon romaanista on löydettävissä ajatus ympäristöalitajunnasta, joka alleviivaa ympäristön ja luonnon merkitystä ihmiselle.
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9 x 12 cm