A role for TASK-1 (KCNK3) channels in the chemosensory control of breathing

Acid-sensitive K+ channels of the tandem P-domain K+-channel family (TASK-1 and TASK-3) have been implicated in peripheral and central respiratory chemosensitivity; however, because of the lack of decisive pharmacological agents, the final proof of the role of the TASK channel in the chemosensory control of breathing has been missing. In the mouse, TASK-1 and TASK-3 channels are dispensable for central respiratory chemosensitivity (Mulkey et al., 2007Go). Here, we have used knock-out animals to determine whether TASK-1 and TASK-3 channels play a role in the carotid body function and chemosensory control of breathing exerted by the carotid body chemoreceptors. Ventilatory responses to hypoxia (10% O2 in inspired air) and moderate normoxic hypercapnia (3–6% CO2 in inspired air) were significantly reduced in TASK-1 knock-out mice. In contrast, TASK-3-deficient mice showed responses to both stimuli that were similar to those developed by their wild-type counterparts. TASK-1 channel deficiency resulted in a marked reduction of the hypoxia (by 49%)- and CO2 (by 68%)-evoked increases in the carotid sinus nerve chemoafferent discharge recorded in the in vitro superfused carotid body/carotid sinus nerve preparations. Deficiency in both TASK-1 and TASK-3 channels increased baseline chemoafferent activity but did not cause a further reduction of the carotid body chemosensory responses. These observations provide direct evidence that TASK-1 channels contribute significantly to the increases in the carotid body chemoafferent discharge in response to a decrease in arterial PO2 or an increase in PCO2/[H+]. TASK-1 channels therefore play a key role in the control of ventilation by peripheral chemoreceptors

Evaluation and Mission-Specific Optimization of Satellite Packet Telemetry Protocol for Use on DoD Flight Test Ranges

The DoD test range community has come to the realization that its telemetry abilities are obsolete. Efforts are therefore underway to improve telemetry systems at DoD test ranges. The overall objective of this project was to evaluate the practical use of the CCSDS packet telemetry protocol in DoD test ranges and determine the configuration that would maximize performance based on mission requirements. A secondary objective was to compare the CCSDS and ATM protocols in order to substantiate further exploration of using ATM in future DoD telemetry systems. Modeling and simulation of the CCSDS protocol showed a correlation between three CCSDS parameters and the resulting throughput and data quality performance. Flight tests confirmed the correlation between the CCSDS parameters and the resulting protocol performance, and narrowed in on the CCSDS configurations that would maximize data throughput, data quality, or provide a combined \u27best of both worlds\u27 solution. In general, flight test results matched those of the modeling and simulation work. Data collected also indicated that performance of the ATM protocol is sufficiently close to that of CCSDS to warrant further investigation of using ATM on test ranges. ATM offers the military user straightforward interoperability with civilian systems/networks

ESTIMATED IMPACT OF NON-PRICE COORDINATION OF FED CATTLE PURCHASES ON MEAT PACKER PROCESSING COSTS

Stochastic simulation of daily slaughter level was used in conjunction with an estimated packing plant cost curve to assess potential reductions in processing costs due to improved vertical coordination between feedlots and packing plants. Results indicate that processing cost reductions of $1 to$5 per head may be possible. Savings result from ensuring a more stable processing volume that is near the plant's cost-minimizing level of production.cattle, cost curve, meat packing, vertical coordination, Industrial Organization, Livestock Production/Industries,

Evaluation of beryllium for space shuttle components

Application of beryllium to specific full-scale space shuttle structural components and assemblies was studied. Material evaluations were conducted to check the mechanical properties of as-received material to gain design information on characteristics needed for the material in the space shuttle environment, and to obtain data needed for evaluating component and panel tests. Four beryllium structural assemblies were analyzed and designed. Selected components of these assemblies, representing areas of critical loading or design/process uncertainty, were designed and tested, and two panel assemblies were fabricated. Trends in cost and weight factors were determined by progressive estimation at key points of preliminary design, final design, and fabrication to aid in a cost/weight evaluation of the use of beryllium