Whole-stream metabolism: strategies for measuring and modeling diel trends of dissolved oxygen

Stream metabolism is used to characterize the allochthonous and autochthonous basis of stream foodweb production. The metabolic rates of respiration and gross primary production often are estimated from changes in dissolved O2 concentration in the stream over time. An upstream–downstream O2 accounting method (2-station) is used commonly to estimate metabolic rates in a defined length of stream channel. Various approaches to measuring and analyzing diel O2 trends have been used, but a detailed comparison of different approaches (e.g., required reach length, method of measuring aeration rate [k], and use of temperature-corrected metabolic rates) is needed. We measured O2 upstream and downstream of various reaches in Kings Creek, Kansas. We found that 20 m was the approximate minimum reach length required to detect a significant change in O2, a result that matched the prediction of a calculation method to determine minimum reach length. We assessed the ability of models based on 2-station diel O2 data and k measurements in various streams around Manhattan, Kansas, to predict k accurately, and we tested the importance of accounting for temperature effects on metabolic rates. We measured gas exchange directly with an inert gas and used a tracer dye to account for dilution and to measure velocity and discharge. Modeled k was significantly correlated with measured k (Kendall's τ, p < 0.001; regression adjusted R²  =  0.70), but 19 published equations for estimating k generally provided poor estimates of measured k (only 6 of 19 equations were significantly correlated). Temperature correction of metabolic rates allowed us to account for increases in nighttime O2, and temperature-corrected metabolic rates fit the data somewhat better than uncorrected estimates. Use of temperature-correction estimates could facilitate cross-site comparisons of metabolism

Shuttle orbiter Ku-band radar/communications system design evaluation. Ku band bent-pipe channel performance evaluation

Because of difficulties with the bit detector of the SPA mode 1 channel 3 input port, a new bit synchronizer was required. The two prime candidate designs are described and analyzed. The selected design is a modification of one which utilizes a phase frequency detector to track the received data clock frequency and a mid-bit transition point sample detector to generate a bit timing error (phase error) signal to control the relative phase between the local clock and the local data stream. The model used to calculate the effects of cable attenuation and rise time degradation is discussed

Accuracy of urinary human papillomavirus testing for presence of cervical HPV: systematic review and meta-analysis

This is an Open Access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 3.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/3.0/.Funding: This study did not receive any fundin

URINARY TESTING FOR HPV Authors' reply to Vorsters and colleagues

This is the peer reviewed published version of the following article: URINARY TESTING FOR HPV Authors' reply to Vorsters and colleagues, which has been published in final form at 10.1136/bmj.g6253. This article may be used for non-commercial purposes in accordance with BMJ's Terms and Conditions for Self-Archiving. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/ by/4.0

Engineering evaluations and studies. Report for Ku-band studies, exhibit A

System performance aspects of the Ku band radar communication hardware and investigations into the Ku band/payload interfaces are discussed. The communications track problem caused by the excessive signal dynamic range at the servo input was investigated. The management/handover logic is discussed and a simplified description of the transmitter enable logic function is presented. Output noise produced by a voltage-controlled oscillator chip used in the SPA return-link channel 3 mid-bit detector is discussed. The deployed assembly (DA) and EA-2 critical design review data are evaluated. Cross coupling effects on antenna servo stability were examined. A series of meetings on the acceptance test specification for the deployed assembly is summarized

What does the Iowa farmer want from radio market news?

Most of the results in this report are based on a personal interview survey of Iowa open-country farmers. Ninety-six percent (178,000) of the operators of Iowa open-country farms sold one or more of Iowa\u27s six top cash farm income products in 1948. About 92 percent of the open-country zone farm operators listened to day-to-day broadcasts of market reports* before making their last sales of butcher hogs, cattle, corn, soybeans, cream or whole milk and eggs

Shuttle Ku-band and S-band communications implementation study

Various aspects of the shuttle orbiter S-band network communication system, the S-band payload communication system, and the Ku-band communication system are considered. A method is proposed for obtaining more accurate S-band antenna patterns of the actual shuttle orbiter vehicle during flight because the preliminary antenna patterns using mock-ups are not realistic that they do not include the effects of additional appendages such as wings and tail structures. The Ku-band communication system is discussed especially the TDRS antenna pointing accuracy with respect to the orbiter and the modifications required and resulting performance characteristics of the convolutionally encoded high data rate return link to maintain bit synchronizer lock on the ground. The TDRS user constraints on data bit clock jitter and data asymmetry on unbalanced QPSK with noisy phase references are included. The S-band payload communication system study is outlined including the advantages and experimental results of a peak regulator design built and evaluated by Axiomatrix for the bent-pipe link versus the existing RMS-type regulator. The nominal sweep rate for the deep-space transponder of 250 Hz/s, and effects of phase noise on the performance of a communication system are analyzed

Shuttle orbiter Ku-band radar/communications system design evaluation

Tasks performed in an examination and critique of a Ku-band radar communications system for the shuttle orbiter are reported. Topics cover: (1) Ku-band high gain antenna/widebeam horn design evaluation; (2) evaluation of the Ku-band SPA and EA-1 LRU software; (3) system test evaluation; (4) critical design review and development test evaluation; (5) Ku-band bent pipe channel performance evaluation; (6) Ku-band LRU interchangeability analysis; and (7) deliverable test equipment evaluation. Where discrepancies were found, modifications and improvements to the Ku-band system and the associated test procedures are suggested

Space Shuttle program communication and tracking systems interface analysis

The Space Shuttle Program Communications and Tracking Systems Interface Analysis began April 18, 1983. During this time, the shuttle communication and tracking systems began flight testing. Two areas of analysis documented were a result of observations made during flight tests. These analyses involved the Ku-band communication system. First, there was a detailed analysis of the interface between the solar max data format and the Ku-band communication system including the TDRSS ground station. The second analysis involving the Ku-band communication system was an analysis of the frequency lock loop of the Gunn oscillator used to generate the transmit frequency. The stability of the frequency lock loop was investigated and changes to the design were reviewed to alleviate the potential loss of data due the loop losing lock and entering the reacquisition mode. Other areas of investigation were the S-band antenna analysis and RF coverage analysis