76 research outputs found
Cryptography and factorization methods in cryptography
No full textThe Security of the RSA cryptosystem depends on the difficulty of finding the prime factors of large integers. Here we explore some of the factorization techniques currently available in cryptography. After giving an overview of cryptography we discuss some of the factorization techniques like Fermat’s factoring, Pollards p-1 method and continued fraction method. We then explore the theory of binary quadratic forms and its applications to factorization.M.S.Includes bibliographical referencesby Subramanyam Durbh
Transformation of Fusarium
No full textThis Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page
Mechanism of regulation of human RAD51 recombinase through post translational modifications & mediator proteins
No full textRAD51 protein plays an important role in homologous genetic recombination (HR), an essential DNA metabolic process used by cells to faithfully repair the most deleterious forms of DNA damage and maintain genomic integrity. RAD51 along with its bacterial counterpart RecA, bacteriophage UvsX and archaeal RadA have been subjected to genetic and biochemical scrutiny resulting in a plentitude of mechanistic and functional information on formation, regulation and activities of these recombinases. An important disconnect between these two lines of investigation still exists because the recombinase functions of RAD51 are highly regulated through mediator proteins like the BRCA2 recombination mediator, and a host of post translational modifications, namely phosphorylation. The mechanism and biochemical implications of these regulatory processes have not been satisfactorily evaluated in-vitro.
This work characterizes the interaction between RAD51 and the BRCA2 recombination mediator protein using computational methods to generate homology models for this interaction which are validated through experimental data. Using the knowledge gained from our structural model for the RAD51 recombinase, I developed a novel strategy to understand several key mechanisms for the regulation of RAD51 by phosphorylation. RAD51 is phosphorylated by the cABL tyrosine kinase. The mechanistic and functional significance of this event is largely disputed. Using biochemical and single molecule assays reconstituting major activities of RAD51, I have successfully dissected the biochemical mechanism of regulation of RAD51 by the c-Abl kinase. The results of this work strongly correlate with observations made in previous cell based analysis.Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2018-05-01The student, Shyamal Subramanyam, accepted the attached license on 2016-03-28 at 18:02.The student, Shyamal Subramanyam, submitted this Dissertation for approval on 2016-03-28 at 18:14.This Dissertation was approved for publication on 2016-04-15 at 14:23.DSpace SAF Submission Ingestion Package generated from Vireo submission #9125 on 2016-07-07 at 14:16:20Made available in DSpace on 2016-07-07T21:14:30Z (GMT). No. of bitstreams: 18
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Previous issue date: 2016-04-15Embargo set by: Seth Robbins for item 93233
Lift date: 2018-07-07T21:14:52Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemEmbargo set by: Seth Robbins for item 93233
Lift date: 2018-07-07T21:18:16Z
Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemLimited Restriction Lifted for Item 93233 on 2018-07-08T09:15:09Z
Acute effects of maternal immune activation and its interaction with Gabrb3 on mouse fetal development
No full textAutism spectrum disorder (ASD) is a group of neuro-developmental disorders characterized by social communication deficits and repetitive behaviors. ASD is believed to be caused by a number of genetic and environmental risk factors and complex interactions between them. Human clinical studies have shown an association between bacterial and viral infections in pregnant women during the first and second trimesters and ASD in their offspring. In addition, studies using animal models have linked an inflammatory state in the mother to ASD-relevant behaviors in the offspring, but the molecular mechanisms mediating the influence of these prenatal risk factors on behavior are unknown. To understand the acute effects of maternal immune activation (MIA) on embryonic neurobiological abnormalities, we administered bacterial mimetic lipopolysaccharide (LPS) and viral mimetic poly inosinic: cytidilic acid (Poly I:C) during mid-gestation in pregnant mice. In this period, the placenta, though vulnerable to environmental insults, allows for most fetuses to survive to term and for cortical neurogenesis to actively occur in the fetal brain. Twenty four hours after LPS and Poly I:C administration, we observed defects in neocortical neural progenitor proliferation and apical cytoarchitecture, differentiation and lineage specification. We also report variations in responses to LPS and Poly I:C, suggesting a differential vulnerability. Finally, we show a unique gene - environment interaction study with MIA and Gabrb3, one of the genes implicated in ASD, leading to synergistic adverse effects on pregnancy
Concentration in Knowledge Output: A case of Economics Journals
No full textThis paper assesses the degree of author concentration in seven economics journals, which were published in India during 1990-2002. To measure the degree of author concentration, Lotka's Law was used. Moreover, we also make an exploratory analysis of the geographic, economics subfield and institutional concentration in 704 economics journals. An important finding of this paper is that specialized journals in the sample report the highest degree of author concentration. This result is quite similar to the findings by Cox and Chung (1991). Furthermore, there are several instances showing that the journals lean towards certain norms; this may affect the flow of innovative ideas into economics. We conclude that a knowledge activity, involving the high degree of concentration and a biased publication process, may affect the flow of new ideas into the discipline.Concentration, Lotka's Law
Alteration of proteins and pigments influence the function of photosystem I under iron deficiency from Chlamydomonas reinhardtii.
No full textBACKGROUND: Iron is an essential micronutrient for all organisms because it is a component of enzyme cofactors that catalyze redox reactions in fundamental metabolic processes. Even though iron is abundant on earth, it is often present in the insoluble ferric [Fe (III)] state, leaving many surface environments Fe-limited. The haploid green alga Chlamydomonas reinhardtii is used as a model organism for studying eukaryotic photosynthesis. This study explores structural and functional changes in PSI-LHCI supercomplexes under Fe deficiency as the eukaryotic photosynthetic apparatus adapts to Fe deficiency. RESULTS: 77K emission spectra and sucrose density gradient data show that PSI and LHCI subunits are affected under iron deficiency conditions. The visible circular dichroism (CD) spectra associated with strongly-coupled chlorophyll dimers increases in intensity. The change in CD signals of pigments originates from the modification of interactions between pigment molecules. Evidence from sucrose gradients and non-denaturing (green) gels indicates that PSI-LHCI levels were reduced after cells were grown for 72 h in Fe-deficient medium. Ultrafast fluorescence spectroscopy suggests that red-shifted pigments in the PSI-LHCI antenna were lost during Fe stress. Further, denaturing gel electrophoresis and immunoblot analysis reveals that levels of the PSI subunits PsaC and PsaD decreased, while PsaE was completely absent after Fe stress. The light harvesting complexes were also susceptible to iron deficiency, with Lhca1 and Lhca9 showing the most dramatic decreases. These changes in the number and composition of PSI-LHCI supercomplexes may be caused by reactive oxygen species, which increase under Fe deficiency conditions. CONCLUSIONS: Fe deficiency induces rapid reduction of the levels of photosynthetic pigments due to a decrease in chlorophyll synthesis. Chlorophyll is important not only as a light-harvesting pigment, but also has a structural role, particularly in the pigment-rich LHCI subunits. The reduced level of chlorophyll molecules inhibits the formation of large PSI-LHCI supercomplexes, further decreasing the photosynthetic efficiency
Inter frame compression of 3D dynamic point clouds
No full textIn recent years Virtual Reality (VR) and Augmented Reality (AR) applications have seen a drastic increase in commercial popularity. Different representations have been used to create 3D reconstructions for AR and VR. Point clouds are one such representation that are characterized by their simplicity and versatility making them suitable for real time applications. However point clouds are unorganized and identifying redundancies to use for compressing them is challenging. For the compression of time varying or dynamic sequences it is critical to identify temporal redundancies that can be used to describe predictors and further compress streams of point clouds. Most of the previous research into point cloud compression relies on the octree data structure. However this approach was used on relatively sparse datasets. Recently, new dense photorealistic point cloud datasets have become available with the ongoing standardization activities on point cloud compression. To compress them using existing octree based codecs is computationally expensive as the tree depth required to achieve a reasonable level of detail is much higher than what was used previously. We propose a point cloud codec that terminates the octree at a fixed level of detail and encodes additional information in an enhancement layer. We also add inter prediction to the enhancement layer in order to gain further bit rate savings. We validate our codec by evaluating it in the framework set up by standardization organizations such as MPEG. We then demonstrate an improvement over the current MPEG anchor codec
Subjective QoE Evaluation of User-Centered Adaptive Streaming of Dynamic Point Clouds
No full textTechnological advances in head-mounted displays and novel real-time 3D acquisition and reconstruction solutions have fostered the development of 6 Degrees of Freedom (6DoF) teleimmersive systems for social VR applications. Point clouds have emerged as a popular format for such applications, owing to their simplicity and versatility; yet, dense point cloud contents are too large to deliver directly over bandwidth-limited networks. In this context, user-adaptive delivery mechanisms are a promising solution to exploit the increased range of motion offered by 6DoF VR applications to yield gains in perceived quality of 3D point cloud user representations, while reducing their bandwidth requirements. In this paper, we perform a user study in VR to quantify the gains adaptive tile selection strategies can bring with respect to non-adaptive solutions. In particular, we define an auxiliary utility function, we employ established methods from the literature and newly-proposed schemes for distributing the bit budget across the tiles, and we evaluate them together with non-adaptive streaming baselines through subjective QoE assessment. Results confirm that considerable gains can be obtained with user-adaptive streaming, achieving bit rate gains of up to 65% with respect to a non-adaptive approach to deliver comparable quality. Our analysis provides useful insights for the design and development of social VR applications. Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Multimedia ComputingIntelligent System
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