Alliant Techsystems (United States)

The capsid (CA) protein of the human immunodeficiency virus type 1 (HIV-1) is an essential structural component of a virion and facilitates many crucial life cycle steps through interactions with host cell factors. Capsid shields the reverse transcription complex from restriction factors while it enables trafficking to the nucleus by hijacking various adaptor proteins, such as FEZ1 and BICD2. In addition, the capsid facilitates the import and localization of the viral complex in the nucleus through interaction with NUP153, NUP358, TNPO3, and CPSF-6. In the later stages of the HIV-1 life cycle, CA plays an essential role in the maturation step as a constituent of the Gag polyprotein. In the final phase of maturation, Gag is cleaved, and CA is released, allowing for the assembly of CA into a fullerene cone, known as the capsid core. The fullerene cone consists of ~250 CA hexamers and 12 CA pentamers and encloses the viral genome and other essential viral proteins for the next round of infection. As research continues to elucidate the role of CA in the HIV-1 life cycle and the importance of the capsid protein becomes more apparent, CA displays potential as a therapeutic target for the development of HIV-1 inhibitors.

Dr. Walton's research efforts focus on impacting technology-sensitive industries by creating sustainable, lean

Testing of identical dual-mode scramjet flowpath geometries in the freejet and direct-connect configurations was conducted in two separate facilities. These tests enabled a comparison study between the two configurations, which was directed toward the determination of the effects of inlet distortion and backpressure on the performance and operability of a dual-mode scramjet. Bulk flow conditions were matched between the two facilities at the isolator entrance plane to simulate Mach 4.8 flight, and a series of metrics were established to quantify similarities and differences. The effects of flowpath backpressure in the direct-connect case were seen to be isolated to regions close to the exhaust. An approximate 10% decrease in combustor pressure rise and consequently integrated pressure force were observed in the freejet configuration; shock train length, however, remained the same. Mode transition was delayed from an equivalence ratio of in the direct-connect case to in the freejet configuration. Further, ignition difficulties were experienced in the freejet tests which were not encountered in those of direct-connect tests, limiting the scope of comparable test points. This work represents the first attempt at a quantitative comparison in the literature of an identical direct-connect and freejet dual-mode scramjet.

Fifty years ago, America was in the middle of the space race to the Moon. The Surveyor program was planned to investigate potential landing sites for the Apollo missions that would follow before the end of the decade. ATK’s Elkton Division (formerly Thiokol) was under contract to Hughes Aircraft to develop and qualify the main retro motor for the soft landing mission. The year 1964 would see the completion of the development of the Surveyor retro motor followed by qualification and flight deliveries. The development of the motor had many challenges such as a consumable igniter, an all-composite nozzle, a high energy propellant for the times, a high strength steel case, and a safe-and-arm device all contributing to a high propellant mass fraction assembly. A summary of the Surveyor program, the function of the propulsion elements in the soft landing mission, and the development and qualification of the retro motor is provided. The propulsion development for the Surveyor program will be highlighted; in particular, the challenges faced in scaling the Elkton high-performance nozzle assemblies. The paper further covers the legacy from the Surveyor motor into other high-performance STARTM motor designs and flight experience into the present day.

The general electromagnetic properties and design methodology for serpentine/folded-waveguide (FW) amplifiers are presented. In addition, hybrid-waveguide circuit topologies, which permit greater design flexibility than the basic serpentine/FW topologies, are also introduced, and their dispersion characteristics are discussed. Experimental validation of design methodology and tools is provided via test results of the recently demonstrated wideband 220-GHz serpentine amplifier, which embodies the design methodology described herein. Particular attention will be paid to the comparison between code prediction and experimental data, which are in excellent agreement.

Designs and simulated performance for W-band traveling wave tubes are presented for three slow wave structure types (dielectric, serpentine waveguide, and cavity-loaded helix). Output powers are 120 and 245 W at 94 GHz for dielectric and serpentine, respectively, with 5–6 GHz bandwidth (9 GHz in serpentine with equalization).

We develop and evaluate methods to separate seismic source, attenuation (Q), spreading, and site effects, to improve corrections for regional amplitudes. We use relative spectra for nearby, similar event pairs, to cancel path and site effects, and estimate reliable corner frequencies and relative moments. We process a large dataset for Eurasia. We compare source terms estimated from direct phases and L g coda to verify the results or flag discrepancies. We then fit source-corrected spectra to estimate Q, spreading, and site terms, and obtain a consistent set of absolute moments. At every stage, we compare our results to existing calibration terms, showing good agreement in many cases, but also serious errors that impact P/S discrimination, as shown for Iran. Our delivered results can be used as constraints in amplitude tomography analyses to improve calibration.