Knowledge of the critical temperature, T(*), the temperature at which a phase change occurs, grea... more Knowledge of the critical temperature, T(*), the temperature at which a phase change occurs, greatly improves the efficiency of simulated annealing when used for optimization or inversion. A numerical method of accurately determining T(*) in a relatively short computation time has been developed. This method is used to recover the seismic soundspeed profile from wavefield data, a problem in which cycle skipping causes many local minima of the energy function and the averaging of the medium by finite length waves results in many states with similar energies. Computations indicate that it is cost-effective to spend about 80 percent of the computing budget looking for T(*) instead of annealing, and that in the course of finding T(*) many states with energies near the global minimum will also be found. The a posteriori probability distribution of the solution has been constructed from trial solutions generated at T(*).
The Journal of the Acoustical Society of America, 1989
The problem here is finding the profile m̄ that minimizes E(m̄) = ‖d̄ − ḡ(m̄)‖ − ε‖m̄ − m̄0‖ in w... more The problem here is finding the profile m̄ that minimizes E(m̄) = ‖d̄ − ḡ(m̄)‖ − ε‖m̄ − m̄0‖ in which d̄ is a data set, m̄0 is the bias, and ḡ is a Green's function. If ḡ is nonlinear and the dimension of m̄ is large, then finding Emin is difficult. Simulated annealing (SA) seeks Emin by sampling from the probability distribution p(m̄) = exp[− E(m̄)/T]/Z in which T is so small that p spikes at Emin. This would be silly if one had to generate Z numerically, but SA does not need to know Z. The physical analogy for SA is that each component of m̄ is an atom in a melt having temperature T and free energy E. Rapid cooling of the melt gives a glass (high E) but slow cooling gives a single crystal (low E). Problems with SA are that slow cooling consumes the computer budget faster than it finds Emin and that the freezing temperature Tc is difficult to determine. Accordingly, much research on SA concerns cooling schedules that do not require Tc. In wave field inversion problems, it was f...
ABSTRACTWe report the development and evaluation of safety and immunogenicity of a whole virion i... more ABSTRACTWe report the development and evaluation of safety and immunogenicity of a whole virion inactivated SARS-COV-2 vaccine (BBV152), adjuvanted with aluminium hydroxide gel (Algel), or a novel TLR7/8 agonist adsorbed Algel. We used a well-characterized SARS-CoV-2 strain and an established vero cell platform to produce large-scale GMP grade highly purified inactivated antigen, BBV152. Product development and manufacturing were carried out in a BSL-3 facility. Immunogenicity was determined at two antigen concentrations (3μg and 6μg), with two different adjuvants, in mice, rats, and rabbits. Our results show that BBV152 vaccine formulations generated significantly high antigen-binding and neutralizing antibody titers, at both concentrations, in all three species with excellent safety profiles. The inactivated vaccine formulation containing TLR7/8 agonist adjuvant-induced Th1 biased antibody responses with elevated IgG2a/IgG1 ratio and increased levels of SARS-CoV-2 specific IFN-γ+ ...
The unprecedented severity of the COVID-19 pandemic caused by a novel human coronavirus SARS-CoV-... more The unprecedented severity of the COVID-19 pandemic caused by a novel human coronavirus SARS-CoV-2 has posed one of the most gigantic multidimensional challenges to the public health systems globally1. One major challenge has been the urgent need to find easily executable and economical means of deactivating the virus in the environment such as surface decontamination, commonly used and shared public utility items and non-disposable personnel protective gear. Several techniques ranging from radiation exposure, chemical inactivation, electrostatic and heat treatment have been experimented with and reported for other coronaviruses2. While the detailed structural organization of the SARS-CoV-2 remains incompletely understood, identifying the sensitivity of the virus to environmental factors such as heat and relative humidity has emerged as a key research focus in the context of virus inactivation. This is not only from an economic feasibility viewpoint for developing lowcost mass-scale thermal-based inactivation application but also the fact that climatologic parameters such as temperature and humidity may be important factors in the pandemic dynamics and geographical variations, if any, as suggested by others3.
Knowledge of the critical temperature, T(*), the temperature at which a phase change occurs, grea... more Knowledge of the critical temperature, T(*), the temperature at which a phase change occurs, greatly improves the efficiency of simulated annealing when used for optimization or inversion. A numerical method of accurately determining T(*) in a relatively short computation time has been developed. This method is used to recover the seismic soundspeed profile from wavefield data, a problem in which cycle skipping causes many local minima of the energy function and the averaging of the medium by finite length waves results in many states with similar energies. Computations indicate that it is cost-effective to spend about 80 percent of the computing budget looking for T(*) instead of annealing, and that in the course of finding T(*) many states with energies near the global minimum will also be found. The a posteriori probability distribution of the solution has been constructed from trial solutions generated at T(*).
The Journal of the Acoustical Society of America, 1989
The problem here is finding the profile m̄ that minimizes E(m̄) = ‖d̄ − ḡ(m̄)‖ − ε‖m̄ − m̄0‖ in w... more The problem here is finding the profile m̄ that minimizes E(m̄) = ‖d̄ − ḡ(m̄)‖ − ε‖m̄ − m̄0‖ in which d̄ is a data set, m̄0 is the bias, and ḡ is a Green's function. If ḡ is nonlinear and the dimension of m̄ is large, then finding Emin is difficult. Simulated annealing (SA) seeks Emin by sampling from the probability distribution p(m̄) = exp[− E(m̄)/T]/Z in which T is so small that p spikes at Emin. This would be silly if one had to generate Z numerically, but SA does not need to know Z. The physical analogy for SA is that each component of m̄ is an atom in a melt having temperature T and free energy E. Rapid cooling of the melt gives a glass (high E) but slow cooling gives a single crystal (low E). Problems with SA are that slow cooling consumes the computer budget faster than it finds Emin and that the freezing temperature Tc is difficult to determine. Accordingly, much research on SA concerns cooling schedules that do not require Tc. In wave field inversion problems, it was f...
ABSTRACTWe report the development and evaluation of safety and immunogenicity of a whole virion i... more ABSTRACTWe report the development and evaluation of safety and immunogenicity of a whole virion inactivated SARS-COV-2 vaccine (BBV152), adjuvanted with aluminium hydroxide gel (Algel), or a novel TLR7/8 agonist adsorbed Algel. We used a well-characterized SARS-CoV-2 strain and an established vero cell platform to produce large-scale GMP grade highly purified inactivated antigen, BBV152. Product development and manufacturing were carried out in a BSL-3 facility. Immunogenicity was determined at two antigen concentrations (3μg and 6μg), with two different adjuvants, in mice, rats, and rabbits. Our results show that BBV152 vaccine formulations generated significantly high antigen-binding and neutralizing antibody titers, at both concentrations, in all three species with excellent safety profiles. The inactivated vaccine formulation containing TLR7/8 agonist adjuvant-induced Th1 biased antibody responses with elevated IgG2a/IgG1 ratio and increased levels of SARS-CoV-2 specific IFN-γ+ ...
The unprecedented severity of the COVID-19 pandemic caused by a novel human coronavirus SARS-CoV-... more The unprecedented severity of the COVID-19 pandemic caused by a novel human coronavirus SARS-CoV-2 has posed one of the most gigantic multidimensional challenges to the public health systems globally1. One major challenge has been the urgent need to find easily executable and economical means of deactivating the virus in the environment such as surface decontamination, commonly used and shared public utility items and non-disposable personnel protective gear. Several techniques ranging from radiation exposure, chemical inactivation, electrostatic and heat treatment have been experimented with and reported for other coronaviruses2. While the detailed structural organization of the SARS-CoV-2 remains incompletely understood, identifying the sensitivity of the virus to environmental factors such as heat and relative humidity has emerged as a key research focus in the context of virus inactivation. This is not only from an economic feasibility viewpoint for developing lowcost mass-scale thermal-based inactivation application but also the fact that climatologic parameters such as temperature and humidity may be important factors in the pandemic dynamics and geographical variations, if any, as suggested by others3.
Uploads
Papers by Atanu Basu