CELSS and regenerative life support for manned missions to MARS

In the mid 1990's, the space station will become a point from which inter-planetary vehicles can be launched. The practicalities of a manned Mars mission are now being studied, along with some newer concepts for human life support. Specifically, the use of organisms such as plants and algae as the basis for life support systems is now being actively considered. A Controlled Ecological Life Support System (CELSS) is composed of several facilities: (1) to grow photosynthetic plants or algae which will produce food, oxygen and potable water, and remove carbon dioxide exhaled by a crew; (2) to process biomass into food; (3) to oxidize organic wastes into CO2; and (4) to maintain system operation and stability. Such a system, when compared to using materials stored at launch, may have distinct weight and cost advantages, depending upon crew size and mission duration, as well as psychological benefits for the crew. The use of the system during transit, as well as in establishing a re-visitable surface camp, will increase the attractiveness of the CELSS concept for life support on interplanetary missions

Lightweight composite reflector panels

The Hexel Corp. has produced additional composite panels, based on JPL designs, that: (1) have increased the panel size from 0.15 to 0.40 meters, (2) have improved the as-manufactured surface precision 3.0 to approx. 1.0 micron RMS, (3) have utilized different numbers of face sheet plys, (4) have improved face sheet fiber orientation, (5) have variations of aluminum honeycomb core cell size, (6) have combined graphite/epoxy (Gr/Ep) face sheets with E-glass honeycomb cores, and (7) have used standard aluminum core with face sheets composed of combinations of glass, Kevlar, and carbon fibers. Additionally, JPL has identified candidate alternate materials for the facesheets and core, modified the baseline polymer panel matrix material, and developed new concepts for panel composite cores. Dornier designed and fabricated three 0.6 meter Gr/Ep panels, that were evaluated by JPL. Results of both the Hexel and Dornier panel work were used to characterize the state-of-the-art for Gr/Ep mirrors

The earth's trapped radiation belts

The near-earth charged particle environment is discussed in terms of spacecraft design criteria. Models are presented of the trapped radiation belts and based on in-situ data obtained from spacecraft

Muscarinic Acetylcholine Receptor M1’s Impact on Fear Extinction Learning

Post-Traumatic Stress Disorder (PTSD) is a mental health disorder that can occur following a traumatic event like combat, assault, or disaster. Individuals with PTSD are unable to extinguish fear memories which can become chronic and disabling. However, it remains unclear why some individuals exposed to a traumatic event develop PTSD while others are resilient. Acetylcholine plays a critical role in fear learning, but its role in fear extinction is less well understood. In this investigation, we used a rat model of fear extinction to determine if individual differences in extinction learning are correlated with markers of cholinergic signaling. Cholinergic markers included the M1 muscarinic acetylcholine receptor (M1 m-AChR) and the vesicular acetylcholine transporter (vAChT). These cholinergic markers are strongly expressed in brain regions, such as the amygdala and prefrontal cortex that contribute to the fear extinction circuit. The goal of the present study was to determine whether individual differences in cholinergic signaling in these brain regions could underlie differences in fear extinction. Expression levels of cholinergic markers were measured in amygdala and prefrontal cortex from male Long-Evans rats (N = 13) that had undergone a Pavlovian fear conditioning and extinction paradigm. We found that rats exhibited individual differences in extinction of freezing behavior following twenty presentations of a conditioned auditory stimulus. Six of 13 rats tested failed to extinguish cue-conditioned freezing behavior as defined by a median split in freezing during the last 10 tone presentations. When M1 m-AChR expression in these animals was assessed by Western blot analysis, a significant correlation was evident between expression level of M1 m-AChR in the amygdala and the freezing behavior during the extinction trials. Expression of M1 m-AChRs in amygdala of animals showing good extinction learning was significantly higher than that in animals resistant to extinction. In contrast, there was no significant correlation between vAChT expression and freezing in either amygdala or prefrontal cortex. These results suggest that low expression of M1 m-AChRs in the amygdala is correlated with deficits in fear extinction, and suggest that therapeutic strategies aimed at enhancing muscarinic signaling in amygdala may enhance fear extinction in animals and perhaps patients with PTSD

Paramagnon-induced dispersion anomalies in the cuprates

We report the self-energy associated with RPA magnetic susceptibility in the hole-doped Bi_2Sr_2CuO_6 (Bi2201) and the electron-doped Nd_{2-x}Ce_xCuO_4 (NCCO) in the overdoped regime within the framework of a one-band Hubbard model. Strong weight is found in the magnetic spectrum around (pi, 0) at about 360 meV in Bi2201 and 640 meV in NCCO, which yields dispersion anomalies in accord with the recently observed `waterfall' effects in the cuprates.Comment: Submitted to PRL, Dec. 21, 2006; 4 eps figures, revte

The chemistry of Antarctic ozone 1960-1987

The factors that influence Antarctic ozone are examined with a view to understanding the observed historical trend. Researchers show that reduced ambient temperatures can dramatically enhance the efficiency of chemical removal processes. Attention is focused on positive feedback between levels of ozone, temperature, and rates of heterogeneous chemical reactions. ClO and its dimer, and high levels of these gases are maintained until the clouds evaporate, on 15 September for the simulation shown here

Acute Patella Subluxation in Crossfit Athlete

Please refer to the pdf version of the abstract located adjacent to the title