962 resultados para Rational first integral


Relevância:

20.00% 20.00%

Publicador:

Resumo:

This thesis treats Githa Hariharan s first three novels The Thousand Faces of Night (1992), The Ghosts of Vasu Master (1994) and When Dreams Travel (1999) as a trilogy, in which Hariharan studies the effects of storytelling from different perspectives. The thesis examines the relationship between embedded storytelling and the primary narrative level, the impact of character-bound storytelling on personal development and interpersonal relationships. Thus, I assume that an analysis of the instabilities between characters, and tensions between sets of values introduced through storytelling displays the development of the central characters in the novels. My focus is on the tensions between different sets of values and knowledge systems and their impact on the gender negotiations. The tensions are articulated through a resistance and/or adherence to a cultural narrative, that is, a formula, which underlies specific narratives. Conveyed or disputed by embedded storytelling, the cultural narrative circumscribes what it means to be gendered in Hariharan s novels. The analysis centres on how the narratee in The Thousand Faces of Night and the storyteller in The Ghosts of Vasu Master relate to and are affected by the storytelling, and how they perceive their gendered positions. The analysis of the third novel When Dreams Travel focuses on storytelling, and its relationship to power and representation. I argue that Hariharan's use of embedded storytelling is a way to renegotiate and even reconceptualise gender. Hariharan s primary concern in all three novels is the tensions between tradition or repetition, and change, and how they affect gender. Although the novels feature ancient mythical heroes, mice and flies, or are set in a fantasy world of jinnis and ghouls, they are, I argue, deeply concerned with contemporary issues. Whereas the first novel questions the demands set by family and society on the individual, the second strives to articulate an ethical relationship between the self and the other. The third novel examines the relationship between representation and power. These issues could not be more contemporary, and they loom large over both the regional and global arenas.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Fujikawa's method of evaluating the supercurrent and the superconformal current anomalies, using the heat-kernel regularization scheme, is extended to theories with gauge invariance, in particular, to the off-shell N=1 supersymmetric Yang-Mills (SSYM) theory. The Jacobians of supersymmetry and superconformal transformations are finite. Although the gauge-fixing term is not supersymmetric and the regularization scheme is not manifestly supersymmetric, we find that the regularized Jacobians are gauge invariant and finite and they can be expressed in such a way that there is no one-loop supercurrent anomaly for the N=1 SSYM theory. The superconformal anomaly is nonzero and the anomaly agrees with a similar result obtained using other methods.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Fujikawa's method of evaluating the anomalies is extended to the on-shell supersymmetric (SUSY) theories. The supercurrent and the superconformal current anomalies are evaluated for the Wess-Zumino model using the background-field formulation and heat-kernel regularization. We find that the regularized Jacobians for SUSY and superconformal transformations are finite. The results can be expressed in a form such that there is no supercurrent anomaly but a finite nonzero superconformal anomaly, in agreement with similar results obtained using other methods.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Gliomas are the most frequent primary brain tumours. The cardinal features of gliomas are infiltrative growth pattern and progression from low-grade tumours to a more malignant phenotype. These features of gliomas generally prevent their complete surgical excision and cause their inherent tendency to recur after initial treatment and lead to poor long-term prognosis. Increasing knowledge about the molecular biology of gliomas has produced new markers that supplement histopathological diagnostics. Molecular markers are also used to evaluate the prognosis and predict therapeutic response. The purpose of this thesis is to study molecular events involved in the malignant progression of gliomas. Gliomas are highly vascularised tumours. Contrast enhancement in magnetic resonance imaging (MRI) reflects a disrupted blood-brain barrier and is often seen in malignant gliomas. In this thesis, 62 astrocytomas, oligodendrogliomas and oligoastrocytomas were studied by MRI and immunohistochemistry. Contrast enhancement in preoperative MRI was associated with angiogenesis, tumour cell proliferation and histological grade of gliomas. Activation of oncogenes by gene amplification is a common genetic aberration in gliomas. EGFR amplification on chromosome 7p12 occurs in 30-40% of glioblastomas. PDGFRA, KIT and VEGFR2 are receptor tyrosine kinase genes located on chromosome 4q12. Amplification of these genes was studied using in situ hybridisation in the primary and recurrent astrocytomas, oligodendrogliomas and oligoastrocytomas of 87 patients. PDGFRA, KIT or VEGFR2 amplification was found in 22% of primary tumours and 36% of recurrent tumours including low-grade and malignant gliomas. The most frequent aberration was KIT amplification, which occurred in 10% of primary tumours and in 27% of recurrent tumours. The expression of ezrin, cyclooxygenase 2 (COX-2) and HuR was studied immunohistochemically in a series of primary and recurrent gliomas of 113 patients. Ezrin is a cell membrane-cytoskeleton linking-protein involved in the migration of glioma cells. The COX-2 enzyme is implicated in the carcinogenesis of epithelial neoplasms and is overexpressed in gliomas. HuR is an RNA-stabilising protein, which regulates the expression of several proteins including COX-2. Ezrin, COX-2 and HuR were associated with histological grade and the overall survival of glioma patients. However, in multivariate analysis they were not independent prognostic factors. In conclusion, these results suggest that contrast enhancement in MRI can be used as a surrogate marker for the proliferative and angiogenic potential of gliomas. Aberrations of PDGFRA, KIT and VEGFR2 genes, as well as the dysregulated expression of ezrin, COX-2 and HuR proteins, are linked to the progression of gliomas.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The diruthenium(II,III) compound [Ru2Cl(O2CC6H4-p-OMe)4](H2O)0.25 (1) has been prepared and its crystal structure determined by X-ray studies. The crystals belong to the triclinic space group, PImage , and the asymmetric unit consists of one full dimer and two half dimers. The {Ru2(O2CC6H4-p-OMe)4+} units are bridged by chloride ions into an infinite zigzag chain, with an average Ru---Cl distance and Ru---Cl---Ru angle of 2.567(2) Å and 121.0(1)°, respectively. The average Ru---Ru distance of 2.286(1) Å in 1 is comparable with that in analogous tetra-alkylcarboxylates, Ru2Cl(O2CR)4 and tetra-amidates, Ru2Cl(ArCONH)4.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The element-based piecewise smooth functional approximation in the conventional finite element method (FEM) results in discontinuous first and higher order derivatives across element boundaries Despite the significant advantages of the FEM in modelling complicated geometries, a motivation in developing mesh-free methods has been the ease with which higher order globally smooth shape functions can be derived via the reproduction of polynomials There is thus a case for combining these advantages in a so-called hybrid scheme or a `smooth FEM' that, whilst retaining the popular mesh-based discretization, obtains shape functions with uniform C-p (p >= 1) continuity One such recent attempt, a NURBS based parametric bridging method (Shaw et al 2008b), uses polynomial reproducing, tensor-product non-uniform rational B-splines (NURBS) over a typical FE mesh and relies upon a (possibly piecewise) bijective geometric map between the physical domain and a rectangular (cuboidal) parametric domain The present work aims at a significant extension and improvement of this concept by replacing NURBS with DMS-splines (say, of degree n > 0) that are defined over triangles and provide Cn-1 continuity across the triangle edges This relieves the need for a geometric map that could precipitate ill-conditioning of the discretized equations Delaunay triangulation is used to discretize the physical domain and shape functions are constructed via the polynomial reproduction condition, which quite remarkably relieves the solution of its sensitive dependence on the selected knotsets Derivatives of shape functions are also constructed based on the principle of reproduction of derivatives of polynomials (Shaw and Roy 2008a) Within the present scheme, the triangles also serve as background integration cells in weak formulations thereby overcoming non-conformability issues Numerical examples involving the evaluation of derivatives of targeted functions up to the fourth order and applications of the method to a few boundary value problems of general interest in solid mechanics over (non-simply connected) bounded domains in 2D are presented towards the end of the paper

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The purpose of this research project was to understand the steps of the retrotransposon BARE (BArley REtrotransposon) life cycle, from regulation of transcription to Virus-Like Particle (VLP) formation and ultimate integration back into the genome. Our study concentrates mainly on BARE1 transcriptional regulation because transcription is the crucial first step in the retrotransposon life cycle. The BARE element is a Class I LTR (Long Terminal Repeat) retrotransposon belonging to the Copia superfamily and was originally isolated in our research group. The LTR retrotransposons are transcribed from promoters in the LTRs and encode proteins for packaging of their transcripts, the reverse transcription of the transcripts into cDNA, and integration of the cDNA back into the genome. BARE1 is translated as a single polyprotein and cleaved into the capsid protein (GAG), integrase (IN), and reverse transcriptase-RNaseH (RT-RH) by the integral aspartic proteinase (AP). The BARE retrotransposon family comprises more than 104 copies in the barley (Hordeum vulgare) genome. The element is bound by long terminal repeats (LTRs, 1829 bp) containing promoters required for replication, signals for RNA processing, and motifs necessary for the integration of the cDNA. Members of the BARE1 subfamily are transcribed, translated, and form virus-like particles. Several basic questions concerning transcription are explored in the thesis: BARE1 transcription control, promoter choice in different barley tissues, start and termination sites for BARE transcripts, and BARE1 transcript polyadenylation (I). Polyadenylation is an important step during mRNA maturation, and determines its stability and translatability among other characteristics. Our work has found a novel way used by BARE1 to make extra GAG protein, which is critical for VLP formation. The discovery that BARE1 uses one RNA population for protein synthesis and another RNA population for making cDNA has established the most important step of the BARE1 life cycle (III). The relationship between BARE1 and BARE2 has been investigated. Besides BARE, we have examined the retrotransposon Cassandra (II), which uses a very different transcriptional mechanism and a fully parasitic life cycle. In general, this work is focused on BARE1 promoter activity, transcriptional regulation including differential promoter usage and RNA pools, extra GAG protein production and VLP formation. The results of this study give new insights into transcription regulation of LTR retrotransposons.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

A method to obtain a nonnegative integral solution of a system of linear equations, if such a solution exists is given. The method writes linear equations as an integer programming problem and then solves the problem using a combination of artificial basis technique and a method of integer forms.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Various Tb theorems play a key role in the modern harmonic analysis. They provide characterizations for the boundedness of Calderón-Zygmund type singular integral operators. The general philosophy is that to conclude the boundedness of an operator T on some function space, one needs only to test it on some suitable function b. The main object of this dissertation is to prove very general Tb theorems. The dissertation consists of four research articles and an introductory part. The framework is general with respect to the domain (a metric space), the measure (an upper doubling measure) and the range (a UMD Banach space). Moreover, the used testing conditions are weak. In the first article a (global) Tb theorem on non-homogeneous metric spaces is proved. One of the main technical components is the construction of a randomization procedure for the metric dyadic cubes. The difficulty lies in the fact that metric spaces do not, in general, have a translation group. Also, the measures considered are more general than in the existing literature. This generality is genuinely important for some applications, including the result of Volberg and Wick concerning the characterization of measures for which the analytic Besov-Sobolev space embeds continuously into the space of square integrable functions. In the second article a vector-valued extension of the main result of the first article is considered. This theorem is a new contribution to the vector-valued literature, since previously such general domains and measures were not allowed. The third article deals with local Tb theorems both in the homogeneous and non-homogeneous situations. A modified version of the general non-homogeneous proof technique of Nazarov, Treil and Volberg is extended to cover the case of upper doubling measures. This technique is also used in the homogeneous setting to prove local Tb theorems with weak testing conditions introduced by Auscher, Hofmann, Muscalu, Tao and Thiele. This gives a completely new and direct proof of such results utilizing the full force of non-homogeneous analysis. The final article has to do with sharp weighted theory for maximal truncations of Calderón-Zygmund operators. This includes a reduction to certain Sawyer-type testing conditions, which are in the spirit of Tb theorems and thus of the dissertation. The article extends the sharp bounds previously known only for untruncated operators, and also proves sharp weak type results, which are new even for untruncated operators. New techniques are introduced to overcome the difficulties introduced by the non-linearity of maximal truncations.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The present study evaluates the feasibility of undelimbed Scots pine (Pinus sylvestris L.) for integrated production of pulp and energy in a kraft pulp mill from the technical, economic and environmental points of view, focusing on the potential of bundle harvesting. The feasibility of tree sections for pulp production was tested by conducting an industrial wood-handling experiment, laboratory cooking and bleaching trials, using conventional small-diameter Scots pine pulpwood as a reference. These trials showed that undelimbed Scots pine sections can be processed in favourable conditions as a blend with conventional small-diameter pulpwood without reducing the pulp quality. However, fibre losses at various phases of the process may increase when using undelimbed material. In the economic evaluation, both pulp production and wood procurement costs were considered, using the relative wood paying capability of a kraft pulp mill as a determinant. The calculations were made for three Scots pine first-thinning stands with the breast-height diameter of the removal (6 12 cm) as the main distinctive factor. The supply chains included in the comparison were based on cut-to-length harvesting, whole-tree harvesting and bundle harvesting (whole-tree bundling). With the current ratio of pulp and energy prices, the wood paying capability declines with an increase in the proportion of the energy fraction of the raw material. The supply system based on the cut-to-length method was the most efficient option, resulting in the highest residual value at stump in most cases. A decline in the pulp price and an increase in the energy price improved the competitiveness of the whole-tree systems. With short truck transportation distances and low pulp prices, however, the harvesting of loose whole trees can result in higher residual value at stump in small-diameter stands. While savings in transportation costs did not compensate for the high cutting and compaction costs by the second prototype of the bundle harvester, an increase in transportation distances improved its competitiveness. Since harvesting undelimbed assortments increases nutrient export from the site, which can affect soil productivity, the whole-tree alternatives included in the present study cannot be recommended on infertile peatlands and mineral soils. The harvesting of loose whole trees or bundled whole trees implies a reduction in protective logging residues and an increase in site traffic or payloads. These factors increase the risk of soil damage, especially on peat soils with poor bearing capacity. Within the wood procurement parameters which were examined, the CO2 emissions of the supply systems varied from 13 27 kg m3. Compaction of whole trees into bundles reduced emissions from transportation by 30 39%, but these reductions were insufficient to compensate for the increased emissions from cutting and compaction.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Conditions for quantum topological invariance of classically topological field theories in the path integral formulation are discussed. Both the three-dimensional Chern-Simons system and a Witten-type topological field theory are shown to satisfy these conditions.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Potential transients are obtained by using “Padé approximants” (an accurate approximation procedure valid globally — not just perturbatively) for all amplitudes of concentration polarization and current densities. This is done for several mechanistic schemes under constant current conditions. We invert the non-linear current-potential relationship in the form (using the Lagrange or the Ramanujan method) of power series appropriate to the two extremes, namely near reversible and near irreversible. Transforming both into the Pad́e expressions, we construct the potential-time profile by retaining whichever is the more accurate of the two. The effectiveness of this method is demonstrated through illustrations which include couplings of homogeneous chemical reactions to the electron-transfer step.