Showing papers by "Rajnikant Sharma published in 2016"

Polymyxin B in Combination with Rifampin and Meropenem against Polymyxin B-Resistant KPC-Producing Klebsiella pneumoniae.

Abstract: Safe and effective therapies are urgently needed to treat polymyxin-resistant KPC-producing Klebsiella pneumoniae infections and suppress the emergence of resistance. We investigated the pharmacodynamics of polymyxin B, rifampin, and meropenem alone and as polymyxin B-based double and triple combinations against KPC-producing K. pneumoniae isolates. The rates and extents of killing with polymyxin B (1 to 128 mg/liter), rifampin (2 to 16 mg/liter), and meropenem (10 to 120 mg/liter) were evaluated against polymyxin B-susceptible (PBs) and polymyxin B-resistant (PBr) clinical isolates using 48-h static time-kill studies. Additionally, humanized triple-drug regimens of polymyxin B (concentration at steady state [Css] values of 0.5, 1, and 2 mg/liter), 600 mg rifampin every 12 or 8 h, and 1 or 2 g meropenem every 8 h dosed as an extended 3-h infusion were simulated over 48 h by using a one-compartment in vitro dynamic infection model. Serial bacterial counts were performed to quantify the pharmacodynamic effect. Population analysis profiles (PAPs) were used to assess the emergence of polymyxin B resistance. Monotherapy was ineffective against both isolates. Polymyxin B with rifampin demonstrated early bactericidal activity against the PBs isolate, followed by regrowth by 48 h. Bactericidal activity was sustained at all polymyxin B concentrations of ≥2 mg/liter in combination with meropenem. No two-drug combinations were effective against the PBr isolate, but all simulated triple-drug regimens showed early bactericidal activity against both strains by 8 h that was sustained over 48 h. PAPs did not reveal the emergence of resistant subpopulations. The triple-drug combination of polymyxin B, rifampin, and meropenem may be a viable consideration for the treatment of PBr KPC-producing K. pneumoniae infections. Further investigation is warranted to optimize triple-combination therapy.

Cooperative localization for fixed wing unmanned aerial vehicles

Abstract: In this paper, we investigate how relative measurements between fixed wing unmanned aerial vehicles (UAVs) and known landmarks can be used to cooperatively localize UAVs when GPS signals are not available. A centralized Extended Kalman Filter (EKF) is used to combine local sensor information from all the UAVs to estimate the required states of all the UAVs. We compare the localization accuracy of the cooperative localization algorithm for different relative measurements such as range, bearing, range rate, and line-of-sight rate. The dynamics, IMU, airspeed, and altimeter data used in the algorithm were collected from flight tests by Naval Postgraduate School [1]. However, the relative measurements are simulated using the flight data. The results are then compared against the GPS data available from the flight test.

Application of virtual target based guidance laws to path following of a quadrotor UAV

Abstract: Two missile guidance laws viz. Pursuit Guidance (PG) and Trajectory Shaping (TS), have been adopted to aggressively follow curved, compact trajectories using a quadrotor. The concept of virtual target navigation has been utilized to generate the required curved trajectories. Simulations and flight tests have been performed using a quadrotor and the performance characteristics obtained have been compared with those obtained from Differential Flatness (DF) approach. The various simulation and flight results prove that TS generates smaller position errors and requires lower control effort in comparison to PG and DF.