11,788,531 research outputs found
Optimization of MMX relative quasi-satellite transfer trajectories using primer vector theory
No full textQuasi-satellite orbits (QSO) are stable retrograde parking orbits around Phobos that are currently being considered for JAXA’s upcoming robotic sample return mission Maritan Moons Exploration (MMX). During the proximity operations of MMX, the spacecraft inserted in a high altitude QSO will gradually descend to lower altitude QSOs with suitable transfer and station-keeping techniques between different relative QSOs. Preliminary analysis of two-impulsive planar transfers between relative retrograde orbits utilizing the bifurcated QSOs families is studied to estimate the Δ V costs and time of flights of the transfers. In this paper, differently from previous works, we utilize the initial guesses found through the preliminary results that provide two-impulsive transfer Δ V execution points and optimize the transfers between relative QSOs around Phobos. Primer vector theory is applied to investigate the primer vector of the MMX transfer trajectories to evaluate whether intermediate maneuver or initial/final coasting times along the trajectories can minimize the total Δ V cost between the transfers. Based on the primer vector analysis of the impulse transfer trajectories, it is found that departing and arriving at the same periphobian sides with an additional mid-course impulse results in the optimal impulse solution
Monolithic Carbide-Derived Carbon Films for Micro-Supercapacitors
No full textMicrobatteries with dimensions of tens to hundreds of micrometers that are produced by common microfabrication techniques are poised to provide integration of power sources onto electronic devices, but they still suffer from poor cycle lifetime, as well as power and temperature range of operation issues that are alleviated with the use of supercapacitors. There have been a few reports on thin-film and other micro-supercapacitors, but they are either too thin to provide sufficient energy or the technology is not scalable. By etching supercapacitor electrodes into conductive titanium carbide substrates, we demonstrate that monolithic carbon films lead to a volumetric capacity exceeding that of micro- and macroscale supercapacitors reported thus far, by a factor of 2. This study also provides the framework for integration of high-performance micro-supercapacitors onto a variety of devices
Immunoglobulin Germline Gene Polymorphisms Influence the Function of SARS-CoV-2 Neutralizing Antibodies. Pushparaj et al.
No full textSupplemental tables of "Immunoglobulin Germline Gene Polymorphisms Influence the Function of SARS-CoV-2 Neutralizing Antibodies" by Pushparaj et al.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV
Modern Approaches in IOT and Machine Learning for Cyber Security
No full textDr. Vijay Anand. R, Dr. Jayalakshmi. P, Dr. Spoorthi Pushparaj Shetty, Dr. Mohammed Shahbaz Kha
Immunoglobulin gene usage and affinity maturation in antiviral antibodies
No full textThe ability of antibodies to block infections makes them highly relevant for successful vaccine development. Through the papers described in this thesis, I attempt to characterize the functional and genetic aspects of antiviral antibodies induced by infection and vaccination.In Paper I, we characterized the distribution and maturation of HIV-1 envelope glycoproteins (Env)-specific antibody lineages post-vaccination in different immune compartments of rhesus macaques. Vaccine-induced Env-specific antibody lineages were disseminated across the periphery, lymph node, spleen, and bone marrow (BM) but not in gut tissue. We observed a consistent increase in the somatic hypermutation (SHM) levels of Env-specific antibody sequences after each boost and the SHM levels strongly correlated with the affinity of members from a potent neutralizing antibody lineage.In Paper II, we set out to understand the role of SHM in a broad, potent, public class of antibodies isolated from a healthcare worker who was previously infected with SARS-CoV2. I selected a potent neutralizing antibody and reverted the heavy chain (HC) to the germline sequence. I then sequentially introduced individual or combinations of SHM so that we could test the functional impact of this. We found a substantial gain of antibody potency and breadth when certain SHM mutations were reintroduced, and we identified two key mutations that largely contributed to the breadth of this lineage. Furthermore, we showed that the mature antibody retained neutralizing activity against potential future viral variants by deep mutational scanning (DMS) experiments. A high-resolution structure of this antibody obtained by cryo-electron microscopy (cryo-EM) confirmed important interactions made by the identified SHMs with the SARS-CoV-2 spike (S).In Papers III and IV, we investigated the effect of immunoglobulin heavy chain variable (IGHV) gene polymorphisms on the function of human SARS-CoV-2 antibodies isolated post-infection. We genotyped a cohort of previously infected healthcare workers and evaluated the neutralization activity of germline-reverted and allele-swapped S-specific IGHV1-69*20-using antibodies from two independent donors carrying this allele. Neutralization was retained when reverting the IGHV region to the germline IGHV1- 69∗20 allele but lost when reverting to other IGHV1-69 alleles demonstrating a strong allele-dependence in these antibodies. A high resolution cryo-EM structure of one of the antibodies revealed significant contacts made by two IGHV1-69*20-germline encoded amino acid residues with the S, illustrating the impact of IGHV polymorphisms on antibody functions. We next focused on the IGHV3-30 group of genes, which are frequently used by S-specific antibodies. By IGHV genotype and haplotype analysis we observed that IGHV3-30-3 gene was deleted in many individuals, and the IGHV3-30 alleles were heterogeneously distributed in our cohort. When the IGHV region of an IGHV3-30-3*01 neutralizing antibody was swapped with IGHV3-30 alleles, the neutralization remained unaffected demonstrating functional redundancy within this gene group, at least for this antibody lineage.The results from my doctoral research provide insight into functional and genetic properties of antibodies induced by viral antigens, which have important clinical relevance both for guided-vaccine design and monoclonal antibody therapeutics, and for our general understanding of antibody responses in the population.List of scientific papersI. Phad GE, Pushparaj P, Tran K, Dubrovskaya V, Àdori M, Martinez Murillo P, Vázquez Bernat N, Singh S, Dionne G, O'Dell S, Bhullar K, Narang S, Sorini C, Villablanca EJ, Sundling C, Murrell B, Mascola JR, Shapiro L, Pancera M, Martin M, Corcoran M, Wyatt RT, Karlsson Hedestam GB. Extensive dissemination and intraclonal maturation of HIV Env vaccine-induced B cell responses. Journal of Experimental Medicine. February 2020; 217(2):e20191155. https://doi.org/10.1084/jem.20191155 II. Sheward DJ*, Pushparaj P*, Das H*, Greaney AJ, Kim C, Kim S, Hanke L, Dyrdak R, Lee J, Peacock TP, McInerney G, Albert J, Corcoran M, Bloom JD, Murrell B#, Karlsson Hedestam GB#, Hällberg BM.# Structural basis of broad SARS-CoV-2 cross-neutralization by affinity-matured public antibodies. *These authors contributed equally. [Submitted]III. Pushparaj P, Nicoletto A*, Sheward DJ*, Das H, Castro Dopico X, Perez Vidakovics L, Hanke L, Chernyshev M, Narang S, Kim S, Fischbach J, Ekström S, McInerney G, Hällberg BM, Murrell B, Corcoran M, Karlsson Hedestam GB. Immunoglobulin germline gene polymorphisms influence the function of SARS-CoV-2 neutralizing antibodies. Immunity. January 2023; 56(1):193-206. *These authors contributed equally. https://doi.org/10.1016/j.immuni.2022.12.005 IV. Pushparaj P, Nicoletto A, Castro Dopico X, Sheward DJ, Sungyong Kim, Ekström S, Murrell B, Corcoran M and Karlsson Hedestam GB. Frequent usage of IGHV3-30-3 in SARS-CoV-2 neutralizing antibody responses. Frontiers in Virology. March 2023, Vol 3. https://doi.org/10.3389/fviro.2023.1128253</p
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
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