94 research outputs found
Mitochondrial Import Of tRNA: Mechanistic Studies Of Post- Receptor Translocation
No full textMitochondrial Import Of tRNA: Mechanistic Studies Of Post Receptor Translocation
Import of tRNA from the cytosol into the mitochondria of the kinetoplastid protozoon
Leishmania is a multistep process consisting of the binding of tRNA to specific receptors, its
transfer to an intermediate factor and translocation through the membrane. A functional RNA
import complex (RIC) isolated from Leishmania mitochondria or reconstituted by cloned and
expressed protein subunits are being employed in our laboratory to determine molecular basis of
these steps. The RIC from mitochondria of the kinetoplastid protozoon Leishmania tropica
induces translocation of tRNAs across artificial or natural membranes. tRNA import consists of a
number of discrete steps beginning with the binding of the substrate to a receptor subunit RIC1 or
RIC8A, followed by its transfer to a third subunit RIC9. Subsequently the tRNA passes into the
vesicle interior presumably through a membrane embedded translocation channel, the
composition and properties of which are largely unknown. Although the receptor binding and
transfer steps have been characterized in terms of role of specific subunits, little is known about
the final translocation step.
Specifically the objective of my research was to reconstitute functional import pore
complex on lipid bilayers and determine the permeability of such membrane vesicles by RIC
channel under different biochemical and biophysical conditions with tRNA and other different
small molecules, to carry out structural and functional studies of translocation by site directed
mutagenesis of important subunit gene. These experiments provided detailed insights into the
interaction of RIC with mitochondrial and other membranes.
I have shown that subunits RIC6 and RiC9 polymerize on the membrane to form the
hexamer (RIC6)3-(RIC9)3 in presence of RIC4A formed a R3 complex. The resultant complex R3
induced translocation of tRNA when the pH of the medium was lowered to ~6. This process was
independent of ATP and sensitive to the protonophore m-chlorocarbonylcyanide phenylhydrazone
(CCCP), and to the K+ ionophore valinomycin, but resistant to k+/h+ exchanger nigericin,
indicating the requirement of a membrane potrential Δψm generated by transmembrane proton
gradient. Indeed R3 mediated tRNA translocation could be induced at neutral pH by K+ diffusion
potential of 60-90mV (negative inside). However, translocation was independent of tRNA
sequence, and small molecules such as ATP, oligonucleotides, labeled amino acids could be taken
up by R3 liposomes at pH6.0 in contrast to large molecules such as linearized plasmid DNA
which fails the internalization process and shows the size specificity of R3 complex. My results
indicated that the (RIC6)3-(RIC9)3 complex forms a voltage gated pore similar to mitochondrial
protein import channels. To understand the critical residues involves in proton sensing points
mutants of RIC6 subunits were generated in all the 6 cysteines and 6 histidine residues as some of
those residues are involved in proton sensing in a homologous protein rieske fe-s protein of RIC6.
I have found out the critical cysteine and histidines along the protein chain are responsible for
proton sensing. Atomic force microscopy has been used to find out the nature of the reconstituted
channel in vitro. Atomic Force Microscopy of R3 revealed particles with an asymmetric surface
groove of ~20 nm rim diameter and ~1 nm depth
Recent advances in the use of acoustics across the frequency spectrum in the oil and gas industry
No full textOrchestration and governance in digital platform ecosystems: a literature review and trends
No full textPurpose: Because of the attention increasingly being focused on digital transformation, interest in business models of platform-enabled ecosystems is rising rapidly. Although there are different theoretical views on the role of ecosystems, a synthesis of research, with a focus on governance and orchestration in dynamic, multi-industry eco-systems, is lacking. Design/methodology/approach: A systematic literature review was conducted by following a rigorous search protocol in the scholarly databases covering both journal articles and conference papers These papers were subsequently filtered, and finally, 48 relevant papers were selected for analysis. Findings: The review identifies five key aspects of platform governance design that need close consideration: the meta-organisation or ecosystem design, coordination mechanisms, mechanisms for value co-creation, value appropriation mechanisms and architectural principles. To achieve balance among a set of competing demands, platform leaders need to devote adequate attention to these aspects. Practical implications: Based on a literature review, the authors provide an overview of underlying theoretical views, research methods and key trends to develop a sound theoretical grounding for research on platform governance design. The paper also suggests research gaps in the existing literature and sets directions for researchers to strengthen the understanding of effective platform governance design. The paper also provides valuable information to managers in developing or leading a successful platform ecosystem. Originality/value: The paper uses existing literature published in this topic and original in nature.</p
The Theme of Betrayal in Tagore’s Home and The World
No full textRabindranath Tagore was a prolific author who earned name and fame worldwide for his contribution in literature. Tagore depicts the different shades of man’s life through the characters of his novels. Tagore touches the different issues like : the struggle for freedom, the existence of good and evil of the world. Tagore’s The Home and the World deals with the theme of betrayal and the relationship of husband and wife and how the wife realizes her mistake at the end of the novel This paper is a sincere effort to display how the betrayal of Bimala effects Nikhil’s life and how she is deceived by her idol Sandip
An approach based on Hierarchical Bayesian Graphical Models for measurement interpretation under uncertainty
No full textIt is not uncommon in the field of non-destructive evaluation that multiple measurements encompassing a variety of modalities are available for analysis and interpretation for determining the underlying states of nature of the materials or parts being tested. Despite and sometimes due to the richness of data, significant challenges arise in the interpretation manifested as ambiguities and inconsistencies due to various uncertain factors in the physical properties (inputs), environment, measurement device properties, human errors, and the measurement data (outputs). Most of these uncertainties cannot be described by any rigorous mathematical means, and modeling of all possibilities is usually infeasible for many real time applications.In this work, we will discuss an approach based on Hierarchical Bayesian Graphical Models (HBGM) for the improved interpretation of complex (multi-dimensional) problems with parametric uncertainties that lack usable physical models. In this setting, the input space of the physical properties is specified through prior distributions based on domain knowledge and expertise, which are represented as Gaussian mixtures to model the various possible scenarios of interest for non-destructive testing applications. Forward models are then used offline to generate the expected distribution of the proposed measurements which are used to train a hierarchical Bayesian network. In Bayesian analysis, all model parameters are treated as random variables, and inference of the parameters is made on the basis of posterior distribution given the observed data. Learned parameters of the posterior distribution obtained after the training can therefore be used to build an efficient classifier for differentiating new observed data in real time on the basis of pre-trained models. We will illustrate the implementation of the HBGM approach to ultrasonic measurements used for cement evaluation of cased wells in the oil industry.</p
An open platform centric approach for scalable government service delivery to the poor: The Aadhaar case
No full textThe efficient delivery of government services to the poor, or Bottom of the Pyramid (BOP), faces many challenges. While a core problem is the lack of scalability, that could be solved by the rapid proliferation of platforms and associated ecosystems. Existing research involving platforms focus on modularity, openness, ecosystem leadership and governance, as well as on their impact on innovation, scale and agility. However, existing studies fail to explore the role of platform in scalable e-government services delivery on an empirical level. Based on an in-depth case study of the world's largest biometric identity platform, used by millions of the poor in India, we develop a set of propositions connecting the attributes of a digital platform ecosystem to different indicators for the scalability of government service delivery. We found that modular architecture, combined with limited functionality in core modules, and open standards combined with controlled access and ecosystem governance enabled by keystone behaviour, have a positive impact on scalability. The research provides insights to policy-makers and government officials alike, particularly those in nations struggling to provide basic services to poor and marginalised. This is also one of the few studies to apply platform theory empirically to the e-government domain.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.Information and Communication Technolog
Impact of Time-dependent Annealing on TiO2 Films for CMOS application
No full textPost-deposition annealing (PDA) is the inherent part of sol-gel fabrication process to achieve the optimum device performance, especially in CMOS applications. The annealing removes the oxygen vacancies and improves the structural order of dielectric films. The process also reduces the interface related defects and improves the interfacial properties. In this work, we have integrated the sol-gel spin-coating deposited high-TiO2 films in MOS. The films are fired at 400 degrees C for the duration of 20, 40, 60 and 80 min. The thicknesses of the films were found to be of similar to 30 nm using ellipsometry. The (Al/TiO2/p-Si) devices were examined with current-voltage (I-V) and capacitance-voltage (C-V) at room temperature to understand the influence of firing time. The C-V and I-V characteristic showed a significant dependence on annealing time such as variation in dielectric constant and leakage current. The accumulation capacitance (Cox), dielectric constant (kappa) and the equivalent oxide thickness (EOT) of the film fired for 60 min were found to be 458 pF, 33, and 4.25nm, respectively with a low leakage current density (1.09 10(-6) A/cm(2)) fired for 80 min at + 1 V
Book Review: Fundamentals of Operative Surgery, 2nd edition
No full textBook Title: Fundamentals of Operative SurgeryBook Author: Vipul YagnikPublisher: Wolters Kluwer, Year 2019, 435 pages Format: PDF and EPUB, Hardcover ISBN 9789387506817
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