Signal Design for Improved Ranging Among Multiple Transceivers

"Ultra-BOC" (where "BOC" signifies "binary offset carrier") is the name of an improved generic design of microwave signals to be used by a group of spacecraft flying in formation to measure ranges and bearings among themselves and to exchange telemetry needed for these measurements. Ultra-BOC could also be applied on Earth for diverse purposes -- for example, measuring relative positions of vehicles on highways for traffic-control purposes and determining the relative alignments of machines operating in mines and of construction machines and structures at construction sites. Ultra-BOC provides for rapid and robust acquisition of signals, even when signal-to-noise ratios are low. The design further provides that each spacecraft or other platform constantly strives to acquire and track the signals from the other platforms while simultaneously transmitting signals that provide full range, bearing, and telemetry service to the other platforms. In Ultra-BOC, unlike in other signal designs that have been considered for the same purposes, it is not necessary to maneuver the spacecraft or other platforms to obtain the data needed for resolving integer-carrier-cycle phase ambiguities

Activated Gα Subunits Can Inhibit Multiple Signal Transduction Pathways during Dictyostelium Development

AbstractMutations impairing the GTPase activity of G protein Gα subunits can result in activated Gα subunits that affect signal transduction and cellular responses and, in some cases, promote tumor formation. An analogous mutation in the Dictyostelium Gα4 subunit gene (Q200L substitution) was constructed and found to inhibit Gα4-mediated responses to folic acid, including the accumulation of cyclic nucleotides and chemotactic cell movement. The Gα4-Q200L subunit also severely inhibited responses to cAMP, including cyclic nucleotide accumulation, cAMP chemotaxis, and cellular aggregation. An analogous mutation in the Gα2 subunit (Q208L substitution), previously reported to inhibit cAMP responses (K. Okaichi et al., 1992, Mol. Biol. Cell 3, 735–747), was also found to partially inhibit folic acid chemotaxis. Chemotactic responses to folic acid and cAMP and developmental aggregation were also inhibited by a mutant Gα5 subunit with the analogous alteration (Q199L substitution). All aggregation-defective Gα mutants were capable of multicellular development after a temporary incubation at 4°C and this development was found to be dependent on wild-type Gα4 function. This study indicates that mutant Gα subunits can inhibit signal transduction pathways mediated by other Gα subunits

Inconspicuous Penis

Inconspicous penis refers to a constellation of conditions that make the penis look diminutive and small. This could be secondary to short penile shaft often termed as micropenis. But more commonly, this inconspicuous appearance is secondary to other causes ranging from congenital conditions such as penoscrotal webbing or megaprepuce, developmental conditions like prepubic adiposity that overhang the penis, and iatrogenic causes like trapped penis after adhesions secondary to circumcision. In this paper, we propose to define these entities and provide their descriptions and then to describe their management including surgical correction

The Validity of Peer Review in a General Medicine Journal

All the opinions in this article are those of the authors and should not be construed to reflect, in any way, those of the Department of Veterans Affairs

Software-Reconfigurable Processors for Spacecraft

A report presents an overview of an architecture for a software-reconfigurable network data processor for a spacecraft engaged in scientific exploration. When executed on suitable electronic hardware, the software performs the functions of a physical layer (in effect, acts as a software radio in that it performs modulation, demodulation, pulse-shaping, error correction, coding, and decoding), a data-link layer, a network layer, a transport layer, and application-layer processing of scientific data. The software-reconfigurable network processor is undergoing development to enable rapid prototyping and rapid implementation of communication, navigation, and scientific signal-processing functions; to provide a long-lived communication infrastructure; and to provide greatly improved scientific-instrumentation and scientific-data-processing functions by enabling science-driven in-flight reconfiguration of computing resources devoted to these functions. This development is an extension of terrestrial radio and network developments (e.g., in the cellular-telephone industry) implemented in software running on such hardware as field-programmable gate arrays, digital signal processors, traditional digital circuits, and mixed-signal application-specific integrated circuits (ASICs)

Improved simulation of river water and groundwater exchange in an alluvial plain using the SWAT model

Hydrological interaction between surface and subsurface water systems has a significant impact on water quality, ecosystems and biogeochemistry cycling of both systems. Distributed models have been developed to simulate this function, but they require detailed spatial inputs and extensive computation time. The soil and water assessment tool (SWAT) model is a semi-distributed model that has been successfully applied around the world. However, it has not been able to simulate the two-way exchanges between surface water and groundwater. In this study, the SWAT-landscape unit (LU) model – based on a catena method that routes flow across three LUs (the divide, the hillslope and the valley) – was modified and applied in the floodplain of the Garonne River. The modified model was called SWAT-LUD. Darcy's equation was applied to simulate groundwater flow. The algorithm for surface water-level simulation during flooding periods was modified, and the influence of flooding on groundwater levels was added to the model. Chloride was chosen as a conservative tracer to test simulated water exchanges. The simulated water exchange quantity from SWAT-LUD was compared with the output of a two-dimensional distributed model, surface–subsurface water exchange model. The results showed that simulated groundwater levels in the LU adjoining the river matched the observed data very well. Additionally, SWAT-LUD model was able to reflect the actual water exchange between the river and the aquifer. It showed that river water discharge has a significant influence on the surface–groundwater exchanges. The main water flow direction in the river/groundwater interface was from groundwater to river; water that flowed in this direction accounted for 65% of the total exchanged water volume. The water mixing occurs mainly during high hydraulic periods. Flooded water was important for the surface–subsurface water exchange process; it accounted for 69% of total water that flowed from the river to the aquifer. The new module also provides the option of simulating pollution transfer occurring at the river/groundwater interface at the catchment scale