Paramecium--a model system for studying cellular graviperception.

Experiments under varied gravitational accelerations as well as in density-adjusted media showed that sensation of gravity in protists may be linked to the known principles of mechanosensation. Paramecium, a ciliate with clear graviresponses (gravitaxis and gravikinesis) is an ideal model system to prove this hypothesis since the ciliary activity and thus the swimming behaviour is controlled by the membrane potential. It has also been assumed that the cytoplasmic mass causes a distinct stimulation of the bipolarly distributed mechano-sensitive K+ and Ca2+ ion channels in the plasma membrane in dependence of the spatial orientation of the cell. In order to prove this hypothesis, different channel blockers are currently under investigation. Gadolinium did not inhibit gravitaxis in Paramecium, showing that it does not specifically block gravireceptors. Further studies concentrated on the question of whether second messengers are involved in the gravity signal transduction chain. Exposure to 5 g for up to 10 min led to a significant increase in cAMP.     

High Dynamic GPS Receiver Using Maximum Likelihood Estimationand Frequency Tracking

A new high dynamic global positioning system (GPS) receiver ispresented and its performance characterized by analysis,simulation, and demonstration. The demonstration receiver is abreadboard model capable of tracking a single simulated satellitesignal in pseudorange and range rate. Pseudorange and range rateestimates are made once every 20 ms, using a maximum likelihoodestimator, and are tracked by means of a third-order fadingmemory filter in a feedback configuration. The receiver trackspseudorange with rms errors of under 1 m when subjected tosimulated 50 g, 40 g/s circular trajectories. The tracking thresholdis approximately 28 dB·Hz, which provides 12 dB margin relativethe the minimum specified signal strength, assuming 3.5 dB systemnoise figure and 0 dB antenna gain.     

Century scale solar variability imprinted in the 44Ti activity in meteorites.

The measurements of gamma-activity of the 44Ti (T1/2 = 66.6 years) produced by spallation reaction of galactic cosmic rays (GCR) in Alfianello, Olivenza, Rio Negro, Dhajala and Torino meteorites, which fell in the time interval 1883 AD (Alfianello)-1988 AD (Torino), show a century scale modulation, connected to long-term solar-wind flux variations in the interplanetary space. The variation of the 44Ti activity with the time of fall of meteorites is qualitatively consistent with the Gleissberg solar cycle, but the amplitude is three-four times higher than expected (about 5%) for GCR flux modulated by solar activity, as determined solely by the sunspot number. The cosmogenic 44Ti is a suitable radioisotope for this investigation, but its activity in meteorites is very low. We performed these measurements in the underground low level counting station of Monte dei Cappuccini in Torino, by means of a big hyperpure Ge crystal (approximately 2 kg) in selective coincidence with a heavy NaI (T1) scintillation detector (approximately 28 kg). This system allows a reliable and non destructive measurement of 44Ti (44Sc) in meteorites of 200-1200 g in weight. The background is about 1 count per day in the gamma-peak at 1157 keV of 44Sc in equilibrium with its parent 44Ti. The high stability of the performance allows long-lasting runs (approximately 10(7) s) in order to attain results with a standard deviation up to about 10%.     

Nanotechnology-based molecular test equipment (MTE)

This paper describes original research efforts in the design, simulation, and development of nanotechnology-based molecular test equipment (MTE). This is a research effort for testing printed circuit boards independent of traditional automatic test equipment (ATE) through the fabrication of MTE within integrated circuits (ICs). The MTE is embedded within the IC substrate and encapsulated within nanoprobes that connect between the surface and the substrate of the IC at various functional areas. A process is followed whereby IC device simulation is performed to assess the electrical, chemical, and structural properties of integrated and adjacent substrate devices. Through this approach the nominal and failed device performance parameters of interest to substrate-based MTE are found. Discussion of the development and application of MTE within IC architectures is provided, including such topics as the effect of substrate composition on the design and realization of MTE, interfaces between MTE and IC devices, and reporting of MTE results to the IC surface and technician. Potential application areas within different device functions will also be identified. A chemical structure diagram is also provided to illustrate the implementation of MTE using discrete device configurations with MTE-augmented logic     

Molecular alterations in tumorigenic human bronchial and breast epithelial cells induced by high LET radiation.

Carcinogenesis is a multi-stage process with sequence of genetic events governing the phenotypic expression of a series of transformation steps leading to the development of metastatic cancer. In the present study, immortalized human bronchial (BEP2D) and breast (MCF-10F) cells were irradiated with graded doses of either 150 keV/micrometer alpha particles or 1 GeV/nucleon 56Fe ions. Transformed cells developed through a series of successive steps before becoming tumorigenic in nude mice. Cell fusion studies indicated that radiation-induced tumorigenic phenotype in BEP2D cells could be completely suppressed by fusion with non-tumorigenic BEP2D cells. The differential expressions of known genes between tumorigenic bronchial and breast cells induced by alpha particles and their respective control cultures were compared using cDNA expression array. Among the 11 genes identified to be differentially expressed in BEP2D cells, three (DCC, DNA-PK and p21(CIP1)) were shown to be consistently down-regulated by 2 to 4 fold in all the 5 tumor cell lines examined. In contrast, their expressions in the fusion cell lines were comparable to control BEP2D cells. Similarly, expression levels of a series of genes were found to be altered in a step-wise manner among tumorigenic MCF-10F cells. The results are highly suggestive that functional alterations of these genes may be causally related to the carcinogenic process.     

Safety testing of lithium ion batteries for navy devices

Lithium ion battery technology is being introduced into power supplies used by our armed forces for a variety of applications. In many cases, the same cells and design parameters that support commercial battery packs are being used in military battery packs. This approach is expected to result in a major decrease in the total life cycle cost of the equipment these batteries support. On June 13, 1991, NAVSEA issued INST9310.1B1, which states that all lithium battery powered equipment must undergo safety evaluation and approval prior to fleet use. This safety program governs a process whereby approvals are issued for lithium batteries to be used in specific equipment on ground facilities, surface combatants, air combatants, and/or submarines. The Naval Ordnance Safety and Security Activity (NOSSA) manages the program. The chief technical advisors are Code 644 at NSWC Carderock Division and Code 609A at NSWC Crane Division. This paper describes three battery designs that incorporate lithium ion technology, and the results of battery safety tests conducted in accordance with navy requirements.     

Commercial technology & avionics architecture

As commercial technology has become more embedded in the military community, there have been attendant effects caused by the rapid progress in technology and by obsolescence. Industry has generated many solutions to mitigate these effects, but their limitations are emerging with time. This is a discussion of higher-level approaches to obsolescence solutions and technology insertion problems that have not hitherto been addressed.     

Adaptive Forward Error Control for Digital Satellite Systems

Two hybrid schemes of time-frequency resource sharing to increase the rain margin of Ku-and Ka-band satellite systems are proposed. Scheme 1 requires sharing a small pool of bandwidth for adaptive forward error control coding, sharing a small pool of time frame for rate reduction, and sharing a portion of low frequency time-division multiple access (TDMA) back-up frame for downlink transmission to the rain affected stations. Scheme 2 utilizes variable rate modulation and forward error correction, shares a small pool of time frame for rate reduction, and shares a portion of low frequency TDMA back-up frame. Effective usable capacities of the system using these schemes are calculated. Distribution of resources in order to maximize the effective usable capacity is also analyzed. The results obtained are compared with other adaptive schemes. Preliminary analysis shows that the utilized capacity of scheme 1 exceeds 99 percent of the effective usable capacity possible if it never rains for an outage of 0.05 percent and fade margin of 2.5 dB. For scheme 2 similar performance is achievable at a fade margin of 1.5 dB. For higher outage objectives the loss of effective utilized capacity is higher for scheme 2.