DSN advanced receiver: Breadboard description and test results

A breadboard Advanced Receiver for use in the Deep Space Network was designed, built, and tested in the laboratory. Field testing was also performed during Voyager Uranus encounter at DSS-13. The development of the breadboard is intended to lead towards implementation of the new receiver throughout the network. The receiver is described on a functional level and then in terms of more specific hardware and software architecture. The results of performance tests in the laboratory and in the field are given. Finally, there is a discussion of suggested improvements for the next phase of development

Determination of the wind response of Saturn 5 by statistical methods, volume 1

Statistical analysis of Saturn 5 launch vehicle wind response - Vol.

Optimized tracking of RF carriers with phase noise, including Pioneer 10 results

The ability to track very weak signals from distant spacecraft is limited by the phase instabilities of the received signal and of the local oscillator employed by the receiver. These instabilities ultimately limit the minimum loop bandwidth that can be used in a phase-coherent receiver, and hence limit the ratio of received carrier power to noise spectral density which can be tracked phase coherently. A method is presented for near real time estimation of the received carrier phase and additive noise spectrum, and optimization of the phase locked loop bandwidth. The method was used with the breadboard Deep Space Network (DSN) Advanced Receiver to optimize tracking of very weak signals from the Pioneer 10 spacecraft, which is now more distant that the edge of the solar system. Tracking with bandwidths of 0.1 Hz to 1.0 Hz reduces tracking signal threshold and increases carrier loop signal to noise ratio (SNR) by 5 dB to 15 dB compared to the 3 Hz bandwidth of the receivers now used operationally in the DSN. This will enable the DSN to track Pioneer 10 until its power sources fails near the end of the century

Salmonella enterica prevalence and serotype distribution in swine at slaughter

The objective of this cross-sectional study was to analyze data available from multiple studies conducted by our research team estimating the prevalence of S. enterica, and the serotype d1stribution in swine at slaughter, based on different sample types A total of 1,110 pigs from three large capacity abattoirs located in the Midwestern U S. were individually sampled at slaughter. Individually paired samples collected mcluded. cecal contents and ileocecal lymph nodes. Samples were collected on multiple occasions in all three abattoirs, transported to the laboratory, and processed for the isolation and identification of S. enterica. The overall prevalence of S. enterica, based on cecal contents, mesentenc lymph nodes, and any of the samples (i.e., cecal contents and/or mesenteric lymph nodes) was 54.7%, 27.9%, and 62.6%, respectively. There was a Significant difference (P\u3c0.05) between prevalence estimates based on cecal contents and mesenteric lymph node samples in all three abattoirs, and overall. A variety of S. enterica serotypes was isolated m all abattoirs The average number of serotypes isolated per group was 3.48. This study confirms that the S. entenca prevalence at slaughter in swine is high, requiring attention due to the associated risk of contamination of the abattoir environment. Moreover, our results demonstrate the common occurrence of a high diversity of serotypes in swine at slaughter. This study also shows that both cecal contents and mesenteric lymph nodes should be considered for a better estimate of S. enterica prevalence at slaughter

Resting on transport trailer reduces Salmonella at harvest

A potential intervention strategy to reduce the prevalence of Salmonella enterica at harvest was evaluated, which consisted of resting pigs prior to harvest on their transport vehicle, instead of in the abattoir holding pen. Individual fecal samples were collected at the farm and at the abattoir (n= 120 pigs), where half of the pigs were unloaded, and moved to a holding pen, whereas the other half stayed in the transport trailer

Salmonella prevalence in first pull versus close out market pigs

Identifying potential risk factors to direct intervention strategies is fundamental to reduce the risk of pork contamination with Salmonella. This study was designed to compare the Salmonella prevalence in the first group of pigs selected for slaughter (uFirst pull ) versus the last group of pigs selected for slaughter ( Close out ) from typical commercial finishing barns containing 800 - 1,000 animals. Nine finishing barns from two production sites were included in the study {4 paired samplings from site A, and 5 paired samplings from site B). Each paired sampling consisted in matched groups of pigs from the same barn as the first pair and the close out with a 4-week interval between groups. From each group, individual fecal samples (n = 45) and meat samples (n = 50) were collected, on-farm and at slaughter, respectively. In the laboratory, fecal samples were selectively enriched, and analyzed for the presence of Salmonella by a commercially available antigen-capture ELISA. Meat samples were kept frozen, and thawed for processing. The resulting liquid ( meat juice ) was collected and analyzed for the presence of antibodies against Salmonella by a commercially available ELISA. All lots of pigs housed in the finishing barns studied were Salmonella-positive, based on sampling from first pull and close out . In 7/9 (77.8%) of the studied barns, an increase in Salmonella prevalence was observed, based on both bacteriologic and serologic analysis. Overall, there was an increase of 9.3% (P\u3c0.05) in bacteriologic prevalence, and 25.1% (P\u3c0.05) in serologic prevalence from first pull to close out groups. This study demonstrates that a significant increase of Salmonella prevalence occurs between the first and the last group of pigs from a finishing barn shipped to slaughter. In conclusion, close out groups of finishing pigs constitute a higher risk for Salmonella contamination of pork products

Superconducting d-wave junctions: The disappearance of the odd ac components

We study voltage-biased superconducting planar d-wave junctions for arbitrary transmission and arbitrary orientation of the order parameters of the superconductors. For a certain orientation of the superconductors the odd ac components disappear, resulting in a doubling of the Josephson frequency. We study the sensitivity of this disappearance to orientation and compare with experiments on grain boundary junctions. We also discuss the possibility of a current flow parallel to the junction.Comment: 5 pages, 3 figure

Sampling cecal contents or ileocecal lymph nodes: is it different?

The objective of this study was to compare the prevalence of Salmonella enterica in swine populations estimated by sampling cecal contents versus ileocecal lymph nodes. In each of two abattoirs, four groups of pigs (n=30 pigs per group) were studied. Cecal contents and ileocecal lymph nodes were individually collected and processed for isolation and identification of S. enterica. The overall prevalence found by cecal contents was 40%, whereas by ileocecal lymph nodes it was 22.9% (p\u3c0.05). Combining results from both samples, the prevalence found was 50.8%. The relative sensitivity of cecal content sampling was 79.3%, whereas for ileocecal lymph node sampling it was 45.5%. The agreement (Kappa statistic) between both sample types was 13.1%. This study demonstrates that sampling either cecal contents or ileocecal lymph nodes affects results of S. enterica epidemiological studies. It is recommended that both samples be used

Eliminating the Abattoir Pen Lairages to Decrease the Prevalence of Salmonella in Cull Sows

The study objective, to determine the role of abattoir antemortem pens in preharvest Salmonella enterica contamination, was conducted over 4 sampling periods, February-April 2002. A total of 40 sows were selected for each period at the same collection point and transported to the abattoir. Twenty (20) were unloaded and sent directly to harvest and 20 held in antemortem pen for 2 h before harvest. Samples collected included ileocecal and subiliac lymph nodes, cecal and transverse colon contents, pre-rinse carcass sponge swabs for the right and left carcass sections and chopped meat blocks composited from these carcasses. The percentage of positive samples (all tissues) and cecal content from sows held in the antemortem pens (59%, 55 %, respectively) were significantly higher (P \u3c 0.05) compared to direct delivered (44%, 39 % respectively). This study demonstrates that normal antemortem holding practices contributed to increased Salmonella enterica contamination of the digestive tract