A globally stable attractor that is locally unstable everywhere

We construct two examples of invariant manifolds that despite being locally unstable at every point in the transverse direction are globally stable. Using numerical simulations we show that these invariant manifolds temporarily repel nearby trajectories but act as global attractors. We formulate an explanation for such global stability in terms of the `rate of rotation' of the stable and unstable eigenvectors spanning the normal subspace associated with each point of the invariant manifold. We discuss the role of this rate of rotation on the transitions between the stable and unstable regimes

INERTIAL PARTICLE DYNAMICS IN SIMPLE VORTEX FLOW CONFIGURATIONS

Dynamics of inertial particles differ significantly from that of the underlying fluid flow. This difference in the dynamics of Inertial particles from that of fluid tracers can be exploited to segregate particles by size. While external forces can be used to manipulate the dynamics of such particles, using hydrodynamic forces which are always present in the flows of interest to manipulate inertial particle dynamics offers several advantages. Vorticity is one such phenomenon that is frequently encountered in natural and industrial flows. Thus, the dynamics of inertial particles have been studied in the presence of simple vortex flow configurations in this work, with the aim of gaining better insight into the problem of achieving size based segregation in the presence of vortex flow fields. In the first problem that has been investigated, the dynamics of inertial particles with varying stokes numbers have been studied in a four vortex flow configuration. After stating criteria to ensure that the particles have non-trivial dynamics, the criteria has been used to separate heavy particles from light particles using an array of vortices. The second problem studied is that of particle focusing in microfluidic channels. It is well known that inertial particles in the presence of hydrodynamic forces in microfluidic channel flows, focus into thin bands which can be used to achieve size based separation of such particles. One such force is the force exerted by dean vortices that form in flows through curved micro channels. In this study, we seek to computationally demonstrate that at low Reynolds numbers, particles with higher stokes number tend to cluster around the dean vortices, and thus leading to focused bands in the flow, while lighter particles are dispersed in the channel. While there exists two well established criteria to identify regions in phase space which permit inertial particles to lose their relative velocities and settle down, we introduce a third criteria to identify regions of the four dimensional phase space comprising of two dimensional space and the components of relative velocity in each of the two dimensions, within which the relative velocity of inertial particles may decay with time

Altered regulation of mitogen-activated protein kinases and GLUT4 expression in skeletal muscle, liver, heart and kidney of obese Zucker rat

Metabolic syndrome is characterized by insulin resistance and hyperglycemia. The molecular mechanism(s) underlying this alteration in skeletal muscle, liver, kidneys and heart in metabolic syndrome patients are presently unclear. Recent data have demonstrated that the p38and extracellular-signal-regulated kinases (ERK 1/2) - mitogen-activated protein kinase (MAPK) proteins may be involved in the regulation of (Glucose transporter type 4) GLUT4 expression levels. Other data have suggested that miRNA may also play a role. Purpose: The purpose of this study is to compare the tissue content, phosphorylation of protein kinases (AKT), p38, c-JUN Nterminal kinase(JNK), ERK1/2, GLUT4 and transcriptional factor Myocyte enhancer factor-2 (MEF2) in the skeletal muscle, heart, liver and kidney of insulin resistant obese (fa/fa) and lean Zucker rats. Methods: Skeletal muscle, heart, liver and kidney were obtained from obese (n=6) and lean (n=6) Zucker rats. The amount and phosphorylation status of AKT, p38, JNK, ERK 1/2, GLUT4 and MEF2 were evaluated by immunoblotting. Results: Decreased GLUT4 expression levels were observed in the skeletal muscle, liver and heart of obese Zucker rats compared to lean zucker rats and are associated with alterations in the phosphorylation of MAPK family members.Levels of mir-1and 133a were altered in skeletal and cardiac muscles of obese Zucker rats when compared with their lean counterparts. Conclusions: These results suggest that MAPK members regulate GLUT4 expression differently in various insulin resistant tissues compared to lean counterparts and that these changes may play a key role in insulin resistance associated with glucose dysregulation

A view-based deformation tool-kit, Master\u27s Thesis, August 2006

Camera manipulation is a hard problem since a graphics camera is defined by specifying 11 independent parameters. Manipulating such a high-dimensional space to accomplish specific tasks is difficult and requires a certain amount of expertise. We present an intuitive interface that allows novice users to perform camera operations in terms of the change they want see in the image. In addition to developing a natural means for camera interaction, our system also includes a novel interface for viewing and organizing previously saved views. When exploring complex 3D data-sets a single view is not sufficient. Instead, a composite view built from multiple views may be more useful. While changing a single camera is hard enough, manipulating several cameras in a single scene is still harder. In this thesis, we also present a framework for creating composite views and an interface that allows users to manipulate such views in real-time

FREE RADICAL SCREENING ACTIVITY OF MARINE SPONGE AURORA GLOBOSTELLATA

ABSTRACTObjective: Marine sponges are sessile organisms which produce chemicals to prevent themselves from the predators; these chemicals are thesecondary metabolites. These metabolites are said to contain various biological activities. A research has been made for analyzing the antioxidantactivity of crude extracts of sponges using hexane, ethyl acetate, ethanol, water as solvents and compared using gallic acid as standard antioxidant.Methods: The free radical scavenging activity was analyzed using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical.Results: The significant radical scavenging activity shown by hexane extract with inhibitory concentration IC as 30.62 µg/ml which is nearby theactivity of gallic acid with IC50 5018.93 µg/ml. The method is based on the spectrophotometric measurement of the DPPH concentration change resultingfrom the reaction with an antioxidant.Conclusion: Therefore, based on the analysis the hexane extract of the sponge has shown to have more antioxidants may be due to the presence ofphenols and flavonoids. The research can be further done by the isolation of the antioxidant compound through chromatographic techniques, whichcould come up with the isolation of novel compound for various therapeutics.Keywords: 1,1-diphenyl-2-picryl-hydrazyl, Chemo preventive, Absorbance, Cytotoxic, Antioxidant, Aurora globostellata.Â

Urbanization and urban transport in india: the search for a policy

Urban population in India has increased significantly from 62 million in 1951 to 285 million in 2001 and is estimated to be around 540 million by the year 2021. In terms of percentage of total population, the urban population has gone up from 17% in 1951 to 29% in 2001 and is expected to increase up to around 37% by the year 2021. Consequently, the number and size of cities have also increased significantly. Although circumstances differ considerably across cities in India, certain basic trends which determine transport demand (such as substantial increase in urban population, household incomes, and industrial and commercial activities) are the same. These changes have placed heavy demands on urban transport systems, demand that many Indian cities have been unable to meet. This paper attempts to highlight the need for a cogent urban transport policy without which there will be ad hoc interventions. Such interventions, apart from not adding up to a comprehensive approach, will result in greater confusion. Furthermore, it emphasizes that if there is no worthwhile public transport, it will still need to be reinvented to promote a better quality of life. The need of the hour is formulation of an urban transport strategy that is both pragmatic and holistic in its approach

'Hedge Funds: Stock Pickers or Managers?

For decades, corporate managers have criticised analysts, fund managers, hedge fund managers and private equity professionals for telling them how to run their business, wihout having had the necessary experience. Now hedge fund activists are regularly suggesting operational decisions, and in some cases even in areas traditionally reserved for management. ‘Activism has gone from being frowned upon, something that marks you out as a rogue or maverick, to almost socially responsible.’1 These hedge funds may have become an accepted part of the governance universe but are they actually adding value? Recent studies have answered this question in the affirmative, but what if those companies picked out by hedge funds for their attention were already on their way to outperformance? The observed outperformance may not be due to a hedge fund’s ability to contribute to value creation but a mere reflection of their stock picking abilities. The difficulty is in identifying those companies that would have made typical hedge fund targets but which were not actually targeted, i.e. build an appropriate group of comparable companies. We have developed a statistical model to identify just these companies