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Coincidências em codimensão um e bordismo / Coincidences in codimension one and bordismGustavo de Lima Prado 11 February 2015 (has links)
Neste trabalho, estudamos coincidências entre duas aplicações contínuas f e g, de X em Y, onde X e Y são variedades diferenciáveis, conexas, sendo X fechada (n+1)-dimensional e Y sem bordo n-dimensional. Quando o domínio é a esfera e g é constante, consideramos homomorfismos w\' e w\'\' que juntos determinam o invariante de bordismo normal do par (f,g). Calculamos w\'\' para vários espaços e, em particular, para fibrados esféricos sobre esferas, obtemos que w\'\' é identicamente nulo se, e somente se, Y é trivial ou Y não é um S²-fibrado sobre S⁴. Finalmente, obtemos resultados tipo Wecken quando X é a esfera, e quando X é o espaço projetivo real de dimensão 3 e Y é a esfera de dimensão 2. / In this work, we study coincidences between two maps f and g, from X to Y, where X and Y are smooth manifolds, connected, being X closed (n+1)-dimensional and Y without boundary n-dimensional. When the domain is the sphere and g is constant, we consider homomorphisms w\' and w\'\' which together determine the normal bordism invariant of the pair (f,g). We calculate w\'\' for several spaces and, in particular, for sphere bundles over spheres, we obtain that w\'\' is identically null if and only if Y is trivial or Y is not an S²-bundle over S⁴. Finally, we obtain Wecken type results when X is the sphere, and when X is the 3-dimensional real projective space and Y is the 2-dimensional sphere.
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Role of Jmjd6 in normal and malignant haematopoiesisSepúlveda, Catarina January 2017 (has links)
The finely tuned regulation of haematopoietic stem and progenitor cells (HSPCs) is crucial to sustain normal haematopoiesis. The disruption of the balance between the quiescence state of haematopoietic stem cells (HSCs) and the proliferation/differentiation programs that are necessary to meet daily haematopoietic demands and respond to external insults, can lead to malignant transformation, such as acute myeloid leukaemia (AML). Therefore, it is essential to investigate the players that are responsible to maintain haematopoietic homeostasis, so that novel therapeutic targets can be identified. HSCs reside in a hypoxic environment that is crucial for their maintenance, as it protects them from over-proliferation and exhaustion. The response to a limited availability of oxygen is critically mediated by a transcription factor - hypoxia inducible factor (HIF). HIF is predominantly regulated by prolyl hydroxylases (PHDs) that are 2-oxoglutarate (2OG) dependent oxygenases. This superfamily of oxygen-sensing enzymes has been assigned important roles ranging from hypoxia signaling, DNA repair, chromatin modifications and oncogenesis Following the data published by our group attesting that HIF is dispensable for HSC survival and maintenance, we focused our investigation on HIF-independent pathways. This manuscript describes the study of the role of an oxygen-sensor enzyme, member of the 2OG oxygenases and HIF negative regulator, jumonji domain-containing protein 6 (Jmjd6), in normal and malignant haematopoiesis. Our knockout studies deleting Jmjd6 specifically within the haematopoietic system (Jmjd6fl/fl;Vav-iCre) demonstrate that the homeostasis of HSPC pool was compromised and lymphopoiesis was attenuated in Jmjd6-deficient cohorts. Upon transplantation, HSCs lacking Jmjd6 exhibited a defective chimerism and impaired capacity to fully reconstitute haematopoiesis of recipient mice. Thus, Jmjd6 is essential for HSC self-renewal and maintenance. Our assessment of the impact of Jmjd6 deletion in the context of inflammatory response and recovery from treatment with a myelotoxic agent treatment revealed that Jmjd6 is a positive regulator of HSC homeostasis and recovery from cytotoxic stress. There are accumulating data on the importance of epigenetics in the development of haematological malignancies. Being an epigenetic regulator, clearly involved in RNA splicing, we investigated Jmjd6 as possible player in leukaemogenesis. The results from our leukaemic studies unravelled a new biological function for Jmjd6 as a tumour suppressor in Meis1/Hoxa9 murine model. Altogether, our findings offer important novel insights into the biological functions of Jmjd6 and pave the way for further studies to discover on the mechanism of action of this complex enzyme. Our observations add value to the idea that Jmjd6 might constitute a good candidate for cancer diagnosis, that can be use to ameliorate patient’s prognosis and that it can be used to help patient prognosis in the future.
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Action Research In Waste Management : Application to construction and demolition waste in the Stockholm regionAid, Graham, Brandt, Nils January 2010 (has links)
The action research methodology and several of its methods have previously been highlighted and described by the authors as a fitting and rigorous framework approach for complex waste management systems. This was in response to criticism of the ex ante selection of traditional empiric systems analysis tools to provide decision support and ‘sustainable improvement’ in such complex systems which often involve strong human and political factors. Several of the action research methods described have recently been utilized in a case study around mineral (aggregate) construction and demolition waste in the Stockholm region. These methods were integrated through a series of workshops and work areas undergone together with project members from several private and public sectors. Leaving the problem fuzzy (loosely defined) in the beginning; utilizing convergent interviewing, rich pictures and focus groups allowed the researchers and partner stakeholders to identify not one but several problem areas within the system of focus. Indicator creation and a dialectic processes were then used to identify qualitative and quantitative aspects of salience around these problem areas. These resulting indicators were strengthened through a process of verification. Each indicator was then analyzed by what was deemed to be appropriate and transparent means. It is argued that this approach may create better communication, transparency, and understanding by the stakeholders. These factors in turn allowing stronger stakeholder ownership of the process and assisting in more informed decisions and help to provide stability for desired change. However the process was not without its drawbacks such as intense communication and time requirements. / QC 20120110 / Project BRA
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Prevention av stora perinealbristningar vid Sveriges förlossningsavdelningar : En kartläggningsstudieBröms, Anna, Låås, Mia January 2011 (has links)
Bakgrund: I Sverige ökade prevalensen av rupturer grad IV från 2,6% till 4,2% mellan åren 1994-2004. Årligen är det cirka tretusen kvinnor som drabbas av bristningar av grad III och IV i Sverige. Det är en stor spridning mellan Sveriges olika förlossningsavdelningar.Syfte: Syftet var att beskriva åtgärder för prevention av perinealbristningar av grad III och grad IV vid normal förlossning på samtliga förlossningsavdelningar i Sverige.Metod: Deskriptiv kartläggningsstudie med induktiv ansats. Det är en nationell studie som riktar sig till Sveriges alla förlossningsavdelningar. Endast perinealbristning av grad III och grad IV berördes.Resultat: Totalt deltog 38 av 47 (81%) av Sveriges förlossningsavdelningar i studien. Respondenterna var chefsbarnmorskor, avdelningschefer och enhetschefer. Av deltagande förlossningsavdelningar var det 12 (32%) som har någon form av vårdprogram för perinealskydd, många svarar att barnmorskorna utför perinealskydd på rutin. Dock var det inte vedertaget att alltid hålla perinealskydd vid 8% av avdelningarna. 18 avdelningar svarade JA på frågan om särskilda handgrepp användes och då uppgavs Ritgens handgrepp, det norska handgreppet och det finska handgreppet. 74 % använder sig av även andra metoder än handgrepp, framför allt värme (varma handdukar, dukar, handskar, kompresser) som hålls över perineum. Många tog upp vikten av god kommunikation och att hjälpa kvinnan att krysta i rätt tid. Förlossningsställningar som många använde sig av var sidoläge och knästående, medan andra hävdade att knästående ej användes pågrund av den ökande risken för bristningar. 71% av deltagande avdelningar får kontinuerlig utbildning och då nämndes främst workshops och utbildningsdagar.Slutsats: Metoder för att skydda perineum varierar mellan förlossningsavdelningarna i Sverige. På flera av Sveriges förlossningsavdelningar är det inte vedertaget att alltid använda perinealskydd vid normal förlossning. Vad som orsakar detta tros vara att en del barnmorskor, under utbildningen, fått lära sig att inte hålla perinealskydd.Klinisk implikation: Nationella rikitlinjer angående perinealskydd skulle vara av värde för att kunna erbjuda kvinnan vård på samma villkor landet över. Det är av stor vikt att den förlösande barnmorskan är uppmärksam på riskfaktorerna.
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Volatility Forecasting of Crude Oil Future¡ÐUnder Normal Mixture Model and NIG Mixture ModelWu, Chia-ying 30 May 2012 (has links)
This study attempts to capture the behavior of volatility in the commodity futures market by importing the normal mixture GARCH Model and the NIG mixture GARCH model (Normal-inverse Gaussian Mixture GARCH Model). Normal mixture GARCH Model (what follows called NM-GARCH Model) is a model mixed by two to several normal distributions with a specific weight portfolio, and its variance abide by GAECH process. The ability of capturing the financial data with leptokurtosis and fat-tail of NM-GARCH Model is better than Normal GARCH Model and Student¡¦s t GARCH Model.¡CAlso¡AThe Variance of the factor with lower weight in NM-GARCH Model usually higher, and the volatility of the factor with higher weight is lower, which explains the situation happens in the real market that the probability of large fluctuations (shocks) is small, and the probability of small fluctuations are higher. Generally, the volatilities which keeping occurring in common cases are respectively flat, and the shocks usually bring large impacts but less frequent.
NIG Mixture Distribution is a distribution mixed by two to several weighted distributions, and the distribution of every factor abides by NIG Distribution. Compare to Normal Mixture Distribution, NIG Mixture Distribution takes the advantages of NIG Distribution into account, which can not only explain leptokurtosis and the deviation of data, but describe the fat-tail phenomenon more complete as well, because of the both tails of NIG Distribution decreasing slowly.
This study will apply the NM GARCH Model and NIG GARCH Model to the Volatility forecasting of the return rates in the crude oil futures market, and infer the predictive abilities of this two kinds of models are significantly better than other volatility model by implementing parameter estimation, forecasting, loss function and statistic significant test.
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A study of sand-asphalt mixtures: a constitutive model based on a thermomechanical framework and experimental corroborationRavindran, Parag 02 June 2009 (has links)
Asphalt bound mixtures have been put to diverse uses. The complicated nature of
the material and the demanding conditions under which it is used preclude complete
solutions to questions on load bearing capability under field conditions. In proportion
to the quantity of its usage and in acknowledgment of modeling complexity, the
material has been interrogated by many researchers using a variety of mechanical
tests, and a plethora of linear viscoelastic models have been developed. Most models
are intended to account for specific classes of problems.
This work addresses the conspicuous absence of systematic documentation of
normal forces generated as a result of shear. The normal force generated during simple
shear is a clear indication of the nonlinear nature of the material. The effect of fillers
(hydrated lime and limestone), air voids, aggregate gradation, asphalt source and step
loading on normal force generation during torsion is experimentally investigated.
Based on experimental evidence, a non-linear thermomechanical model for sandasphalt
mixtures based on the idea of multiple natural configurations is developed.
The model accounts for the fact that the mixture has a natural configuration (stressfree
configuration) which evolves as it is subjected to loads. Assumptions are made
regarding the manner in which the material stores and dissipates energy. A key assumption is that among the various constitutive relations possible, the one that is
chosen is the one that maximizes the rate of entropy production. The model that is
developed accounts for the anisotropic nature of the response.
The experimental results show that asphalt bound mixtures generate significant
normal forces even at low rotation rates. The source of asphalt, aggregate gradation,
fillers and air voids have a pronounced effect on normal stress generation. The model
is corroborated against data from torsion experiments.
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Advances in the Normal-Normal Hierarchical ModelKelly, Joseph 06 June 2014 (has links)
This thesis consists of results relating to the theoretical and computational advances in modeling the Normal-Normal hierarchical model. / Statistics
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Generalizing the multivariate normality assumption in the simulation of dependencies in transportation systemsNg, Man Wo 22 November 2010 (has links)
By far the most popular method to account for dependencies in the transportation
network analysis literature is the use of the multivariate normal (MVN) distribution.
While in certain cases there is some theoretical underpinning for the MVN assumption, in
others there is none. This can lead to misleading results: results do not only depend on
whether dependence is modeled, but also how dependence is modeled. When assuming
the MVN distribution, one is limiting oneself to a specific set of dependency structures,
which can substantially limit validity of results. In this report an existing, more flexible,
correlation-based approach (where just marginal distributions and their correlations are
specified) is proposed, and it is demonstrated that, in simulation studies, such an
approach is a generalization of the MVN assumption. The need for such generalization is
particularly critical in the transportation network modeling literature, where oftentimes there exists no or insufficient data to estimate probability distributions, so that sensitivity
analyses assuming different dependence structures could be extremely valuable.
However, the proposed method has its own drawbacks. For example, it is again not able
to exhaust all possible dependence forms and it relies on some not-so-known properties
of the correlation coefficient. / text
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Polynomial-Normal extension of Black-Scholes modelLi, Hao Unknown Date
No description available.
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Lärarna och strålning : Gymnasielärarnas inställningar, arbetsförutsättningar och handlingar när det gäller joniserande strålningLindgren, Malin January 2013 (has links)
Detta är en studie som undersöker lärares inställningar kring området joniserande strålning samt hur de upplever arbetsförutsättningarna inom detta område. Studien tar även upp skillnader mellan nya och gamla kursplaner (Lpf94 och Gy11) och läromedel i fysik och biologi analyseras. I studien intervjuades sju gymnasielärare och sex läroböcker analyserades. Som teori har Post normal science (PNS) använts, vilket är en vetenskapsteori som förespråkar att man erkänner och tillåter utomstående aktörer och andra discipliner än sin egna komma in i diskussionen. PNS kräver att man ser på saker från flera olika synvinklar och ämnesområden för att få en helhet. PNS brukar tillämpas när fakta är osäkra, värdena omtvistade och insatserna höga samt när problemet innehåller lika mycket politik och värdering som vetenskap. Resultatet av studien visade att lärarna hade en ganska avspänd inställning till joniserande strålning, ofta med en vetenskaplig grund för sina argument och åsikter. Studien visade också på att undervisningens utformning inte gav eleverna en mångfacetterad bild av strålningsområdet. Detta eftersom lärarna arbetade isolerat i sitt ämne utan något samarbete med lärare i andra ämnen. Till sist visade studien att det inte fanns några tydigt uttryckta skillnader mellan den gamla och nya kursplanen och läromedel kring fältet joniserande strålning, trots att lärarna upplevde vissa skillnader. För att eleverna ska kunna få en helhetsbild kring ett område tror jag att det krävs att lärarna och skolan arbetar med att ge eleverna verktyg för att koppla samman olika ämnessynsätt.
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