Microgrid polarimeters, also known as division of focal plane (DoFP) polarimeters, are composed o... more Microgrid polarimeters, also known as division of focal plane (DoFP) polarimeters, are composed of an integrated array of micropolarizing elements that immediately precedes the FPA. The result of the DoFP device is that neighboring pixels sense different polarization states. The measurements made at each pixel can be combined to estimate the Stokes vector at every reconstruction point in a scene. DoFP devices have the advantage that they are mechanically rugged and inherently optically aligned. However, they suffer from the severe disadvantage that the neighboring pixels that make up the Stokes vector estimates have different instantaneous fields of view (IFOV). This IFOV error leads to spatial differencing that causes false polarization signatures, especially in regions of the image where the scene changes rapidly in space. Furthermore, when the polarimeter is operating in the LWIR, the FPA has inherent response problems such as nonuniformity and dead pixels that make the false polarization problem that much worse. In this paper, we present methods that use spatial information from the scene to mitigate two of the biggest problems that confront DoFP devices. The first is a polarimetric dead pixel replacement (DPR) scheme, and the second is a reconstruction method that chooses the most appropriate polarimetric interpolation scheme for each particular pixel in the image based on the scene properties. We have found that these two methods can greatly improve both the visual appearance of polarization products as well as the accuracy of the polarization estimates, and can be implemented with minimal computational cost.
DESIDOC Bulletin of Information Technology, Mar 1, 2005
The volume of world wide web (WWW) is increasing enormously due to a world wide move to migrate i... more The volume of world wide web (WWW) is increasing enormously due to a world wide move to migrate information to online sources. To search some information on WWW, search engines are used, which when presented with queries, return a list of web pages ranked on the basis of estimation of relevance. Generally the search engines due to the abundance of information available on the web return millions of pages. But user studies indicate that a common user browses through top 10 or 20 documents only. So it's all-important to get into those top 10 documents. To achieve this web authors are increasingly beginning to rely on underhand techniques to ensure their sites get seen, in turn affecting the performance of search engines. The existing measures to evaluate these systems' performance are not adequate in the current world of highly interactive end-user systems. In this study a metric 'Ranked Precision' is proposed to evaluate the performance of search engines.
Proceedings of the National Academy of Sciences, 2006
Estrogen receptor α (ERα) functions as both a transcription factor and a mediator of rapid estrog... more Estrogen receptor α (ERα) functions as both a transcription factor and a mediator of rapid estrogen signaling. Recent studies have shown a role for ERα-interacting membranous and cytosolic proteins in ERα action, but our understanding of the role of the microtubule network in the modulation of ERα signaling remains unclear. Here we found that endogenous ERα associates with microtubules through the microtubule-binding protein hematopoietic PBX-interaction protein (HPIP). Biochemical and RNA-interference studies demonstrated that HPIP influences ERα-dependent rapid estrogen signaling by acting as a scaffold protein and recruits Src kinase and the p85 subunit of phosphatidylinositol 3-kinase to a complex with ERα, which in turn stimulates AKT and MAPK. We also found that ERα interacts with β-tubulin through HPIP. Destabilization of microtubules activated ERα signaling, whereas stabilization of microtubules repressed ERα transcriptional activity in a HPIP-dependent manner. These finding...
Microgrid polarimeters, also known as division of focal plane (DoFP) polarimeters, are composed o... more Microgrid polarimeters, also known as division of focal plane (DoFP) polarimeters, are composed of an integrated array of micropolarizing elements that immediately precedes the FPA. The result of the DoFP device is that neighboring pixels sense different polarization states. The measurements made at each pixel can be combined to estimate the Stokes vector at every reconstruction point in a scene. DoFP devices have the advantage that they are mechanically rugged and inherently optically aligned. However, they suffer from the severe disadvantage that the neighboring pixels that make up the Stokes vector estimates have different instantaneous fields of view (IFOV). This IFOV error leads to spatial differencing that causes false polarization signatures, especially in regions of the image where the scene changes rapidly in space. Furthermore, when the polarimeter is operating in the LWIR, the FPA has inherent response problems such as nonuniformity and dead pixels that make the false polarization problem that much worse. In this paper, we present methods that use spatial information from the scene to mitigate two of the biggest problems that confront DoFP devices. The first is a polarimetric dead pixel replacement (DPR) scheme, and the second is a reconstruction method that chooses the most appropriate polarimetric interpolation scheme for each particular pixel in the image based on the scene properties. We have found that these two methods can greatly improve both the visual appearance of polarization products as well as the accuracy of the polarization estimates, and can be implemented with minimal computational cost.
DESIDOC Bulletin of Information Technology, Mar 1, 2005
The volume of world wide web (WWW) is increasing enormously due to a world wide move to migrate i... more The volume of world wide web (WWW) is increasing enormously due to a world wide move to migrate information to online sources. To search some information on WWW, search engines are used, which when presented with queries, return a list of web pages ranked on the basis of estimation of relevance. Generally the search engines due to the abundance of information available on the web return millions of pages. But user studies indicate that a common user browses through top 10 or 20 documents only. So it's all-important to get into those top 10 documents. To achieve this web authors are increasingly beginning to rely on underhand techniques to ensure their sites get seen, in turn affecting the performance of search engines. The existing measures to evaluate these systems' performance are not adequate in the current world of highly interactive end-user systems. In this study a metric 'Ranked Precision' is proposed to evaluate the performance of search engines.
Proceedings of the National Academy of Sciences, 2006
Estrogen receptor α (ERα) functions as both a transcription factor and a mediator of rapid estrog... more Estrogen receptor α (ERα) functions as both a transcription factor and a mediator of rapid estrogen signaling. Recent studies have shown a role for ERα-interacting membranous and cytosolic proteins in ERα action, but our understanding of the role of the microtubule network in the modulation of ERα signaling remains unclear. Here we found that endogenous ERα associates with microtubules through the microtubule-binding protein hematopoietic PBX-interaction protein (HPIP). Biochemical and RNA-interference studies demonstrated that HPIP influences ERα-dependent rapid estrogen signaling by acting as a scaffold protein and recruits Src kinase and the p85 subunit of phosphatidylinositol 3-kinase to a complex with ERα, which in turn stimulates AKT and MAPK. We also found that ERα interacts with β-tubulin through HPIP. Destabilization of microtubules activated ERα signaling, whereas stabilization of microtubules repressed ERα transcriptional activity in a HPIP-dependent manner. These finding...
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Papers by Rakesh kumar