Modeling the human as a controller in a multitask environment

Modeling the human as a controller of slowly responding systems with preview is considered. Along with control tasks, discrete noncontrol tasks occur at irregular intervals. In multitask situations such as these, it has been observed that humans tend to apply piecewise constant controls. It is believed that the magnitude of controls and the durations for which they remain constant are dependent directly on the system bandwidth, preview distance, complexity of the trajectory to be followed, and nature of the noncontrol tasks. A simple heuristic model of human control behavior in this situation is presented. The results of a simulation study, whose purpose was determination of the sensitivity of the model to its parameters, are discussed

Supervisory sampling and control: Sources of suboptimality in a prediction task

A process supervisor is defined as a person who decides when to sample the process input and what values of a control variable to specify in order to maximize (minimize) a given value function of input sampling period, control setting, and process state. Presented experimental data in such a process where the value function is a time-averaged sampling cost plus mean squared difference between input and control variable. The task was unpaced prediction of the output of a second order filter driven by white noise. Experimental results, when compared to the optical strategy, reveal several consistently suboptimal behaviors. One is a tendency not to choose a long prediction interval even though the optimal strategy dictates that one should. Some results are also interpreted in terms of those input parameters according to which each subjects' behavior would have been nearest optimal. Differences of those parameters from actual input parameters served to quantify how subjects' prediction behavior differed from optimal

INFLUENCE OF P FERTILITY ON SWEETPOTATO ROOTING DURING CONTAINERIZED TRANSPLANT PRODUCTION

A market for edible landscape transplants continues to increase for vegetable production in the home landscape. A method for extending the salability of sweetpotato transplants in retail outlets is needed because containerized transplants can develop spiraling roots and deformed storage roots. Implementing traditional techniques to ameliorate container-bound roots before planting in the landscape is not advisable. Altering P fertility is a non-chemical and non-mechanical method for slowing sweetpotato rooting. Therefore, sweetpotato cuttings were planted in 100% sand-filled containers and fertilized at 0, 5, 10, 15, 20, and 31 mg L-1 using a modified Hoagland solution over a 6-week period. Each week transplant shoots were measured for shoot length, quality, and biomass and roots were analyzed for total root length (TRL), root surface area (RSA), root volume (RV), average root diameter (ARD), and biomass. All sweetpotato transplants fertilized at ≥ 5 mg P L-1 increased in plant length, quality, and biomass for the first four weeks after planting (WAP) followed by declines in transplant quality. Rooting followed a similar pattern for all architectural parameters but continued to increase throughout the duration of the experiments with the exception of the control. Reducing P fertility from 15 to 5 mg L-1 slowed root growth, it was not sufficient to extend the salable period beyond 4 WAP. Therefore, sweetpotato transplants ideally would be established in the landscape within 4 WAP to minimize effects from root spiraling and reduce storage root deformation

Plate Pouring III

This project, Plate Pouring III, is an automated device that fills petri dishes with a liquid solution called Agar. This is done in a sterile environment, not needing any human interaction for the mechanism to function. It safely removes the lid individually from petri dishes, injects the solution, reinserts the lid, and stacks the filled petri dishes

Estimating Heritability of Percentage of Intramuscular Fat and Ribeye Area Measures By Scan Session in Angus Bulls and Heifers

The present study included 3,066 ultrasound-predicted percentage of intramuscular fat (UPFAT) and 4,502 ultrasound ribeye area (UREA) measures of bulls and heifers from the Iowa State University beef cattle breeding project. Data were collected over a four-year period between 1998 and 2001. The objective of the current study was to estimate variance components and heritability of UPFAT and UREA. Data were analyzed based on single- and multiple-trait animal models. Heritability of UPFAT increased from a minimum of 0.36 at a mean age of 37 weeks to a maximum of 0.54 at a mean age of 54 weeks. Heritability of UREA ranged from 0.30 at a mean age of 35 weeks to a maximum of 0.48 at a mean age of 50 weeks. Heritability of yearling UPFAT and UREA were 0.50 and 0.45, respectively. For the range of ages included in the present study the results suggest optimum heritability of UPFAT and UREA starting at about one year of age

Estimation of Heritability and Repeatability of Ultrasound Ribeye Area Measures Using Random Regression Models

The present study included 4,653 observations from 882 Angus bulls and heifers born during the spring of 1998 to 2001. Each year cattle were scanned four to eight times for ribeye area (UREA) and other ultrasound traits, starting at a minimum age of 27 weeks. The objective of the current study was to estimate variance components, heritability, and repeatability of UREA. Direct additive genetic variance increased from 7.11 to 19.4 cm4 as measurement age increased from 27 to 62 weeks. For the same time period direct permanent environmental variance increased from 14.7 to 26.6 cm4. When averaged by four weeks intervals, heritability of UREA ranged from 0.29 to 0.39. Mean repeatability values ranged from 0.80 to 0.86. Yearling heritability and repeatability were estimated at 0.39 and 0.80, respectively. For the range of ages considered, the present results showed an optimum heritability and repeatability of UREA measures around 52 weeks through at least 62 weeks of age

Combinatorial Proofs of Fermat\u27s, Lucas\u27s, and Wilson\u27s Theorems

No abstract provided in this article

Torsion of Noncircular Composite Cylinders

The paper presents a brief overview of the predicted deformation and failure characteristics of noncircular composite cylinders subjected to torsion. Using a numerical analysis, elliptical cylinders with a minor-to-major diameter ratio of 0.7 are considered. Counterpart circular cylinders with the same circumference as the elliptical cylinders are included for comparison. The cylinders are constructed of a medium-modulus graphite-epoxy material in a quasi-isotropic lay-up. Imperfections generated from the buckling mode shapes are included in the initial cross-sectional geometry of the cylinders. Deformations until first fiber failure, as predicted using the maximum stress failure criterion and a material degradation scheme, are presented. For increasing levels of torsion, the deformations of the elliptical cylinders, in the form of wrinkling of the cylinder wall, occur primarily in the flatter regions of the cross section. By comparison the wrinkling deformations of the circular cylinders are more uniformly distributed around the circumference. Differences in the initial failure and damage progression and the overall torque vs. twist relationship between the elliptical and circular cylinders are presented. Despite differences in the response as the cylinders are being loaded, at first fiber failure the torque and twist for the elliptical and circular cylinders nearly coincide

Lentiviral vector design using alternative RNA export elements

<p>Abstract</p> <p>Background</p> <p>Lentiviral vectors have been designed with complex RNA export sequences in both the integrating and packaging plasmids in order to co-ordinate efficient vector production. Recent studies have attempted to replace the existing complex rev/RRE system with a more simplistic RNA export system from simple retroviruses to make these vectors in a rev-independent manner.</p> <p>Results</p> <p>Towards this end, lentiviral transfer plasmids were modified with various cis-acting DNA elements that co-ordinate RNA export during viral production to determine their ability to affect the efficiency of vector titer and transduction in different immortalized cell lines in vitro. It was found that multiple copies of the constitutive transport element (CTE) originating from different simian retroviruses, including simian retrovirus type 1 (SRV-1) and type-2 (SRV-2) and Mason-Pfizer (MPV) could be used to eliminate the requirement for the rev responsive element (RRE) in the transfer and packaging plasmids with titers >10⁶T.U./mL (n = 4–8 preparations). The addition of multiple copies of the murine intracisternal type A particle, the woodchuck post-regulatory element (WPRE), or single and dual copies of the simian CTE had minimal effect on viral titer. Immortalized cell lines from different species were found to be readily transduced by VSV-G pseudotyped lentiviral vectors containing the multiple copies of the CTE similar to the findings in HeLa cells, although the simian-derived CTE were found to have a lower infectivity into murine cell lines compared to the other species.</p> <p>Conclusion</p> <p>These studies demonstrated that the rev-responsive element (RRE) could be replaced with other constitutive transport elements to produce equivalent titers using lentivectors containing the RRE sequence <it>in vitro</it>, but that concatemerization of the CTE or the close proximity of RNA export sequences was needed to enhance vector production.</p