2,964 research outputs found

    Effect of sampling rate and record length on the determination of stability and control derivatives

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    Flight data from five aircraft were used to assess the effects of sampling rate and record length reductions on estimates of stability and control derivatives produced by a maximum likelihood estimation method. Derivatives could be extracted from flight data with the maximum likelihood estimation method even if there were considerable reductions in sampling rate and/or record length. Small amplitude pulse maneuvers showed greater degradation of the derivative maneuvers than large amplitude pulse maneuvers when these reductions were made. Reducing the sampling rate was found to be more desirable than reducing the record length as a method of lessening the total computation time required without greatly degrading the quantity of the estimates

    The new HiVIS spectropolarimeter and spectropolarimetric calibration of the AEOS telescope

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    We designed, built, and calibrated a new spectropolarimeter for the HiVIS spectrograph (R 12000-49000) on the AEOS telescope. We also did a polarization calibration of the telescope and instrument. We will introduce the design and use of the spectropolarimeter as well as a new data reduction package we have developed, then discuss the polarization calibration of the spectropolarimeter and the AEOS telescope. We used observations of unpolarized standard stars at many pointings to measure the telescope induced polarization and compare it with a Zemax model. The telescope induces polarization of 1-6% with a strong variation with wavelength and pointing, consistent with the altitude and azimuth variation expected. We then used scattered sunlight as a linearly polarized source to measure the telescopes spectropolarimetric response to linearly polarized light. We then made an all-sky map of the telescope's polarization response to calibrate future spectropolarimetry.Comment: PASP 118, June 200

    Optical Astronomy from Orbiting Observatories

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    Atmospheric extinction, seeing, and light pollution £re the most significant factors affecting the quality of observations obtained from ground-based optical telescopes, degrading resolution and limiting reach. In addition, the earth\u27s atmosphere is opaque to radiation shorter than 0.3 microns preventing the ultraviolet from being observed in detail from the ground. The solution to these problems has been to move astronomical telescopes into earth orbit. Initially these orbiting observatories carried instruments sensitive to ultraviolet and higher energy radiation since it was otherwise unobservable. The success of the first series of these orbiting observatories, the Orbiting Astronomical Observatories (OAO), established these satellites as one of a new generation of tools for exploring the universe. Another orbiting observatory, the International Ultraviolet Explorer (IUE), is unique among the current orbiting observatories in that it is in a geosynchronous orbit and provides a guest observer facility serving the international community. IUE has had a significant impact on observational astronomy. Nearly 10 percent of all observational papers published JLi the Astrophysical Journal in 1980 reported or used observations made by IUE. The figure for all astronomical satellites is about 3 times higher and continues to rise. With the orbiting of the Space Telescope in the mid 1980s by the Space Shuttle, observational astronomy will enter a new era. For the first time, astronomers will have access to a large (2.4 meter) high-resolution telescope unhindered by the earth f s atmosphere. With the potential such an instrument offers, there is little doubt that the near future will see a large fraction of observational astronomy performed from orbiting observatories

    Non-destructive techniques to assess body composition of birds: a review and validation

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    Abstract Body composition of birds is often used to assess in part the ''condition'' of individuals in the context of their life history and ecology. We describe contemporary non-destructive (non-lethal) techniques that are available for estimating the body composition of free-living birds. We critically evaluate the strengths and weaknesses of these techniques in the context of bird studies. Although most contemporary techniques are based on theory and first principles, assessing their accuracy and precision requires empirical calibrations. We summarize the results of recent validation studies on songbirds and discuss their implications. Deuterium dilution was the best single technique among those compared for measuring lean and fat dynamics in small songbird species that averaged 9-29 g, although we advocate technique(s) that independently estimate each body component. Interspecific models that estimated lean mass using total body electrical conductivity and structural measure(s), and estimated fat mass using deuterium dilution were as accurate (within 0.3-1.1 g of actual lean mass and 0.2-0.9 g of actual fat mass, respectively, depending on bird species) as intraspecific models for songbirds that averaged 13-29 g in body mass. Thus, separate models for each bird species may not be necessary, and the development and testing of interspecific models for estimating body composition is warranted. Several factors, including body size and physiological state, required accuracy and precision, and the scope of predictions must be carefully considered when any of these non-destructive techniques are used to measure the body composition of birds. Keywords Songbird body composition Á Non-destructive techniques Á Total body electrical conductivity Á Deuterium Á Fat score Á DEXA Á QM

    Compliance with surgical care improvement project blood glucose--a marker for euglycemia, but does it put our patients at risk?

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    To improve outcomes in open heart surgery (OHS) patients, the Surgical Care Improvement Project (SCIP) requires 6 am postoperative day (POD) 1 and 2 blood glucose (BG) to be ≤200mg/dL. This study examined risk factors for SCIP noncompliance when using an insulin infusion protocol (IIP) and evaluated this SCIP metric as a surrogate for glycemic control. The authors divided 99 consecutive OHS patients, all subjected to 1 uniform IIP, into 2 groups: Group 1-SCIP compliant (n=79) and Group 2-SCIP noncompliant (n=20). They determined mean BG for the first 48 postoperative hours, percent of total time with hyperglycemia (% time BG \u3e200mg/dL) for each group, and assessed risk of SCIP noncompliance as relates to multiple risk factors including intensity of IIP application, and switching to subcutaneous (SQ) insulin prior to 6 am on POD 2. Group 1 had lower mean BG than Group 2 and percent of total time with hyperglycemia,

    A Cross-National Examination of Expected Correlation of Computer Ethical Perceptions and User Computer Attitudes

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    This study examined computer ethical perceptions and computer use attitudes among three differing groups consisting of nationalities from the United States, Singapore and Hong Kong. The purpose of the study was to determine if computer attitudes have a moderating effect on the perceptions of computer ethical use across multiple cultural backgrounds. Evidence supporting this claim would add additional insight into previously discovered differences. This study found limited support for the suggested hypotheses, but confirmed fundamental cultural differences. Future research should examine other variables to determine if significant effects can be determined from unexamined variable

    PROCESS-CONTROL EFFECTS FOR TEAM-BASEDCOMPUTER-MEDIATED DECISION ANALYSES

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    As the evolution of research in Group Support Systems (GSS) continues, focus must begin to shift away from the concentration of GSS groups versus non-GSS groups, and begin to direct scrutiny toward the examination of the group dynamics that influence the experience of the teams that use GSS. The literature has clearly established that GSS improves the quality of certain decisions. The new challenge is to discover what processes within GSS are responsible for decision improvement and how they interact with other group processes extant in work situation
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