734 resultados para Howell, Timothy
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Diplomityössä tehdään perusselvitys olemassaolevista tiedonsiirtotekniikoista, joita voidaan käyttää teollisuusympäristössä. Tiedonsiirtojärjestelmiä tarvitaan teollisuuden prosessien ja laitteiden ohjauksessa monessa eri tasossa. Ylemmän tason tiedonsiirtoväyliin kuuluu esimerkiksi taloushallinnan talousväylä, jota pitkin tapahtuu operatiivista tiedonsiirtoa. Operatiivinen tiedonsiirto koostuu tuotantotiedonsiirrosta ja koneiden toimintaan liittyvien tietojen siirrosta. Tavoitteena on tuotannon tehostaminen sekä logistiikan ja koneiden käytettävyyden parantaminen. Alemman tason väyliin kuuluu käyttöväylä, joka voi koostua useammasta osaväylästä: tehdasväylästä, prosessiväylästä ja kenttäväylästä. Ohjaustiedonsiirto ja laitteiden välinen tiedonsiirto tapahtuu käyttöväylää pitkin. Tiedonsiirtoa tapahtuu myös laitteiden sisäisesti. Työn alkuosassa esitellään laitteita, joiden välillä voidaan tarvita tiedonsiirtoyhteyttä ja vaatimuksia, joita teollisuusympäristö asettaa tiedonsiirtoyhteyksille. Työssä esitellään teollisuusympäristöön soveltuvien tiedonsiirtotekniikoiden ominaisuuksia ja sovelluksia. Eri tiedonsiirtoyhteyksien toteuttamiseen sopivien tiedonsiirtojärjestelmien valintaa käsitellään esimerkkien valossa. Työssä esitellään myös esimerkkilaitteisto, jonka avulla tutkitaan pienjännitteisen sähköverkon soveltuvuutta tiedonsiirtoon. Työssä esitetään yhteenveto siitä, millä tiedonsiirtotekniikoilla eri laitteiden välinen tiedonsiirto on toteutettavissa ja pohditaan uusien tiedonsiirtotekniikoiden tarjoamia mahdollisuuksia ja niiden käyttöön liittyviä vaatimuksia.
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Background: We use an approach based on Factor Analysis to analyze datasets generated for transcriptional profiling. The method groups samples into biologically relevant categories, and enables the identification of genes and pathways most significantly associated to each phenotypic group, while allowing for the participation of a given gene in more than one cluster. Genes assigned to each cluster are used for the detection of pathways predominantly activated in that cluster by finding statistically significant associated GO terms. We tested the approach with a published dataset of microarray experiments in yeast. Upon validation with the yeast dataset, we applied the technique to a prostate cancer dataset. Results: Two major pathways are shown to be activated in organ-confined, non-metastatic prostate cancer: those regulated by the androgen receptor and by receptor tyrosine kinases. A number of gene markers (HER3, IQGAP2 and POR1) highlighted by the software and related to the later pathway have been validated experimentally a posteriori on independent samples. Conclusion: Using a new microarray analysis tool followed by a posteriori experimental validation of the results, we have confirmed several putative markers of malignancy associated with peptide growth factor signalling in prostate cancer and revealed others, most notably ERRB3 (HER3). Our study suggest that, in primary prostate cancer, HER3, together or not with HER4, rather than in receptor complexes involving HER2, could play an important role in the biology of these tumors. These results provide new evidence for the role of receptor tyrosine kinases in the establishment and progression of prostate cancer.
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The immune system has the potential to protect from malignant diseases for extended periods of time. Unfortunately, spontaneous immune responses are often inefficient. Significant effort is required to develop reliable, broadly applicable immunotherapies for cancer patients. A major innovation was transplantation with hematopoietic stem cells from genetically distinct donors for patients with hematologic malignancies. In this setting, donor T cells induce long-term remission by keeping cancer cells in check through powerful allogeneic graft-versus-leukemia effects. More recently, a long awaited breakthrough for patients with solid tissue cancers was achieved, by means of therapeutic blockade of T cell inhibitory receptors. In untreated cancer patients, T cells are dysfunctional and remain in a state of T cell "exhaustion". Nonetheless, they often retain a high potential for successful defense against cancer, indicating that many T cells are not entirely and irreversibly exhausted but can be mobilized to become highly functional. Novel antibody therapies that block inhibitory receptors can lead to strong activation of anti-tumor T cells, mediating clinically significant anti-cancer immunity for many years. Here we review these new treatments and the current knowledge on tumor antigen-specific T cells.
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The post-graduate teaching of chemistry in Brazil over the last years is discussed, including comparisons with some other sciences and also experiences in the United States and the United Kingdom. We have also compared the more recent situation with the previous decade, which leads us to a favourable conclusion as to the results obtained in the teaching of post-graduate students in chemistry. Some conclusions and recommendations are made with respect to the near future.
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A critical evaluation is presented on the use of faecal sterols for the identification of sewage contamination in Guanabara Bay. Sediments were collected from 8 stations in the bay selected as representative of different contamination levels. GC/MS determination of faecal sterols gave: coprostanol, 335 - 40000 ng g-1; coprostanone, 112-4136 ng g-1; cholesterol, 1407-7800 ng g-1; cholestanol, 2011 - 10900 ng g-1 and cholestanone, 655-7954 ng g-1. The observed concentration is in accordance with the presence of known pollution sources, however, concentration ratios of different sterols species produced unclear results evidently influenced by primary production and microbial processes.
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The olefin metathesis reaction allows the exchange of complex alkyl units between two olefins, with the formation of a new olefinic link and a sub-product olefin usually ethylene. This reaction has found extensive application in the last ten years with the development of the Grubbs and Schrock catalysts, in total synthesis of complex organic molecules, as opposed to the very important use in the petrochemical industry with relatively simple molecules. This review intends to trace a historical and mechanistic pathway from industry to academy, before illustrating the more recent advances.
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Mitochondrial genomes (mitogenomes) are useful and relatively accessible sources of molecular data to explore and understand the evolutionary history and relationships of eukaryotic organisms across diverse taxonomic levels. The availability of complete mitogenomes from Platyhelminthes is limited; of the 40 or so published most are from parasitic flatworms (Neodermata). Here, we present the mitogenomes of two free-living flatworms (Tricladida): the complete genome of the freshwater species Crenobia alpina (Planariidae) and a nearly complete genome of the land planarian Obama sp. (Geoplanidae). Moreover, we have reanotated the published mitogenome of the species Dugesia japonica (Dugesiidae). This contribution almost doubles the total number of mtDNAs published for Tricladida, a species-rich group including model organisms and economically important invasive species. We took the opportunity to conduct comparative mitogenomic analyses between available free-living and selected parasitic flatworms in order to gain insights into the putative effect of life cycle on nucleotide composition through mutation and natural selection. Unexpectedly, we did not find any molecular hallmark of a selective relaxation in mitogenomes of parasitic flatworms; on the contrary, three out of the four studied free-living triclad mitogenomes exhibit higher A+T content and selective relaxation levels. Additionally, we provide new and valuable molecular data to develop markers for future phylogenetic studies on planariids and geoplanids.
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The NAS/CNPq programme in Chemistry ran from 1969 to 1974, and brought recent PhD and post-doctoral chemists to the Chemistry Institutes at the University of São Paulo and the Federal University of Rio de Janeiro. The purpose was to create and direct new research topics in selected areas of chemistry, and participate in the post-graduate programmes. As a participant in this programme, I present my personal views, some background information, and an evaluation of this programme for the advance of synthetic organic chemistry in Brazil.
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The bakkenolide group of sesquiterpenes has been a focal point of synthetic efforts amongst several research laboratories all linked to our common origins at the Chemistry Institute at the State University in São Paulo. In this review we would like to present a historical perspective of this research, with unpublished background information, and a definitive retrosynthetic analysis of these molecules. This chemistry spans the time period from 1972 to 2006, and traces the initial steps with Prof. Dr. Helena Ferraz to the present day.
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The Diels-Alder reaction continues to be the premier method for the construction of complex organic molecules. In the last 10 years many developments have been introduced, and have led to increased utility of this reaction. In this review we present some of these novelties, which are of fundamental importance in organic synthesis.
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Kirjallisuusarvostelu
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Kirjallisuusarvostelu
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Kirjallisuusarvostelu
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The overall purpose of this thesis was to increase the knowledge on the biogeochemistry of rural acid sulphate (AS) soil environments and urban forest ecosystems near small towns in Western Finland. In addition, the potential causal relationship between the distribution of AS soils and geographical occurence of multiple sclerosis (MS) disease was assessed based on a review of existing literature and data. Acid sulphate soils, which occupy an area of approximately 17–24 million hectare worldwide, are regarded as the nastiest soils in the world. Independent of the geographical locality of these soils, they pose a great threat to their surrounding environment if disturbed. The abundant metal-rich acid drainage from Finnish AS soils, which is a result of sulphide oxidation due to artificial farmland drainage, has significant but spatially and temporally variable ecotoxicological impacts on biodiversity and community structure of fish, benthic invertebrates and macrophytes. This has resulted in mass fish kills and even eradication of sensitive fish species in affected waters. Moreover, previous investigations demonstrated significantly enriched concentrations of Co, Ni, Mn and Al, metals which are abundantly mobilised in AS soils, in agricultural crops (timothy grass and oats) and approximately 50 times higher concentrations of Al in cow milk originating from AS soils in Western Finland. Nevertheless, the results presented here demonstrate, in general, relatively moderate metal concentrations in oats and cabbage grown on AS soils in Western Finland, although some of the studied fields showed anomalous values of metals (e.g. Co and Ni) in both the soil and target plants (especially oats), similar to that of the previous investigations. The results indicated that the concentrations of Co, Ni, Mn and Zn in oats and Co and Zn in cabbage were governed by soil geochemistry as these metals were correlated with corresponding concentrations extracted from the soil by NH4Ac-EDTA and NH4Ac, respectively. The concentrations of Cu and Fe in oats and cabbage were uncorrelated to that of the easily soluble concentrations in the soils, suggesting that biological processes (e.g. plant-root processes) overshadow geochemical variation. The concentrations of K and Mg in cabbage, which showed a low spread and were strongly correlated to the NH4Ac extractable contents in the soil, were governed by both the bioavailable fractions in the topsoil and plant-uptake mechanisms. The plant´s ability to regulate its uptake of Ca and P (e.g. through root exudates) seemed to be more important than the influence of soil geochemistry. The distribution of P, K, Ca, Mg, Mn and S within humus, moss and needles in and around small towns was to a high degree controlled by biological cycling, which was indicated by the low correlation coefficients for P, K, Ca, Mg and S between humus and moss, and the low spread of these nutrients in moss and needles. The concentration variations of elements in till are mainly due to natural processes (e.g. intrusions, weathering, mineralogical variations in the bedrock). There was a strong spatial pattern for B in humus, moss and needles, which was suggested to be associated with anthropogenic emissions from nearby town centres. Geogenic dust affected the spatial distribution of Fe and Cr in moss, while natural processes governed the Fe anomaly found in the needles. The spatial accumulation patterns of Zn, Cd, Cu, Ni and Pb in humus and moss were strong and diverse, and related to current industry, the former steel industry, coal combustion, and natural geochemical processes. An intriguing Cu anomaly was found in moss. Since it was located close to a main railway line and because the railway line´s electric cables are made of Cu, it was suggested that the reason for the Cu anomaly is corrosion of these cables. In Western Finland, where AS soils are particularly abundant and enrich the metal concentrations of stream waters, cow milk and to some extent crops, an environmental risk assessment would be motivated to elucidate if the metal dispersion affect human health. Within this context, a topic of concern is the distribution of multiple sclerosis as high MS prevalence rates are found in the main area of AS soils. Regionally, the AS soil type in the Seinäjoki area has been demonstrated to be very severe in terms of metal leaching, this area also shows one of the highest MS rates reported worldwide. On a local scale, these severe AS soil types coincide well with the corresponding MS clustering along the Kyrönjoki River in Seinäjoki. There are reasons to suspect that these spatial correlations are causal, as multiple sclerosis has been suggested to result from a combination of genetic and environmental factors.