Linear rational finite differences from derivatives of barycentric rational interpolants

Derivatives of polynomial interpolants lead in a natural way to approximations of derivatives of the interpolated function, e.g., through finite differences. We extend a study of the approximation of derivatives of linear barycentric rational interpolants and present improved finite difference formulas arising from these interpolants. The formulas contain the classical finite differences as a special case and are more stable for calculating one-sided derivatives as well as derivatives close to boundaries

Linear barycentric rational quadrature

Linear interpolation schemes very naturally lead to quadrature rules. Introduced in the eighties, linear barycentric rational interpolation has recently experienced a boost with the presentation of new weights by Floater and Hormann. The corresponding interpolants converge in principle with arbitrary high order of precision. In the present paper we employ them to construct two linear rational quadrature rules. The weights of the first are obtained through the direct numerical integration of the Lagrange fundamental rational functions; the other rule, based on the solution of a simple boundary value problem, yields an approximation of an antiderivative of the integrand. The convergence order in the first case is shown to be one unit larger than that of the interpolation, under some restrictions. We demonstrate the efficiency of both approaches with numerical test

VIRAL ONCOLYSIS: INCREASED IMMUNOGENICITY OF HOST CELL ANTIGEN ASSOCIATED WITH INFLUENZA VIRUS

A2G mice could be solidly immunized against the Ehrlich ascites tumor by single intraperitoneal injections of homogenized and lyophilized tumor cells which had been infected with oncolytic strains of influenza A virus. Similar homogenates from noninfected tumor cells were not immunogenic, even when mixed with egg-grown virus. The immunizing principle in viral oncolysates could not be separated from the oncolytic virus by differential centrifugation or adsorption to and elution from red cells. It could be inhibited by antibody raised in rabbits against the egg-grown oncolytic virus. This reaction showed serologic specificity. Thus, the immunogenicity of an oncolysate produced with the WSA strain of neurotropic influenza virus could be inhibited by rabbit anti-WSA, but not by rabbit antibody to the TUR strain of fowl plague virus. Conversely, the immunogenicity of an oncolysate prepared with the TUR strain could be inhibited by rabbit anti-TUR, but not by anti-WSA. When mice were preimmunized (primed) with egg-grown WSA virus, their antitumor response to a later injection of WSA oncolysate was of the anamnestic type. Priming with egg-grown influenza B virus had no such effect. It was concluded that the immunogenicity of certain host cell components was greatly increased by incorporation into the makeup of the oncolytic virus

Modeling of Responses and Response Times with the Package cirt

In computerized testing, the test takers' responses as well as their response times on the items are recorded. The relationship between response times and response accuracies is complex and varies over levels of observation. For example, it takes the form of a tradeoff between speed and accuracy at the level of a fixed person but may become a positive correlation for a population of test takers. In order to explore such relationships and test hypotheses about them, a conjoint model is proposed. Item responses are modeled by a two-parameter normal-ogive IRT model and response times by a lognormal model. The two models are combined using a hierarchical framework based on the fact that response times and responses are nested within individuals. All parameters can be estimated simultaneously using an MCMC estimation approach. A R-package for the MCMC algorithm is presented and explained.

The Joint Multivariate Modeling of Multiple Mixed Response Sources: Relating Student Performances with Feedback Behavior

The present study concerns a Dutch computer-based assessment, which includes an assessment process about information literacy and a feedback process for students. The assessment is concerned with the measurement of skills in information literacy and the feedback process with item-based support to improve student learning. To analyze students’ feedback behavior (i.e. feedback use and attention time), test performance, and speed of working, a multivariate hierarchical latent variable model is proposed. The model can handle multivariate mixed responses from multiple sources related to different processes and comprehends multiple measurement components for responses and response times. A flexible within-subject latent variable structure is defined to explore multiple individual latent characteristics related to students’ test performance and feedback behavior. Main results of the computer-based assessment showed that feedback-information pages were less visited by well-performing students when they relate to easy items. Students’ attention paid to feedback was positively related to working speed but not to the propensity to use feedbac

The linear barycentric rational quadrature method for Volterra integral equations

We introduce two direct quadrature methods based on linear rational interpolation for solving general Volterra integral equations of the second kind. The first, deduced by a direct application of linear barycentric rational quadrature given in former work, is shown to converge at the same rate as the rational quadrature rule but is costly on long integration intervals. The second, based on a composite version of this quadrature rule, loses one order of convergence but is much cheaper. Both require only a sample of the involved functions at equispaced nodes and yield an infinitely smooth solution of most classical examples with machine precision

Modeling of Responses and Response Times with the Package cirt

In computerized testing, the test takers' responses as well as their response times on the items are recorded. The relationship between response times and response accuracies is complex and varies over levels of observation. For example, it takes the form of a tradeoff between speed and accuracy at the level of a fixed person but may become a positive correlation for a population of test takers. In order to explore such relationships and test hypotheses about them, a conjoint model is proposed. Item responses are modeled by a two-parameter normal-ogive IRT model and response times by a lognormal model. The two models are combined using a hierarchical framework based on the fact that response times and responses are nested within individuals. All parameters can be estimated simultaneously using an MCMC estimation approach. A R-package for the MCMC algorithm is presented and explained

Can wild boar be surveyed using GPS?

The Global Positioning System (GPS) is an important new technology for spatial behaviour studies of terrestrial vertebrates. Although VHF telemetry has been substantially used, our study is the first report, to our knowledge, on GPS technology used to track free-ranging wild boars. Although the need for collars larger than those used for VHF tracking, the crowded vegetation of habitat and the particular features of social group behaviour of wild boars led to some technical difficulties, three adult sows were successfully fitted with two GPS collars and one dummy GPS. The collars remained on the wild boars for over 283 days without causing any injury to the animals. Forty-one daily cycles (24 hours), as well as daily locations over 142 days, could be recorded for a single animal. Detection efficiency and fixes were better during the night than during the day. In the light of these results, the GPS technique appears to be an efficient tool to study wild boar movements. Progress in the survey of animal movements at a fine scale is of prime interest for animal management programs in order to obtain and maintain a sustainable level of animal population regarding damage problems

The Ursinus Weekly, March 12, 1951

Curtain Club groups to give plays on April 3 • Edna Millay\u27s poetry read at lit meeting • Ursinus on TV Saturday • Club to visit Seminary • Pageant planned • Forum to feature newspaper writer at March 14 session • Physiotherapist, dental school head to address Pre-med society • Speak Easy hailed as milestone in Ursinus theater work • Fraternities, sororities send out bids as Spring rushing period begins today • MSGA discusses election system • Final tryouts for Spring play to be held Wednesday, Thursday • Livingston gives illustrated talk to large crowd • Dr. Yost at Princeton on busman\u27s holiday • Bloodmobile to re-visit • Chess Club ties • Lantern selects material • Editorial: Story of a letter • Book reviewed • Organ was installed in 1916 as memoriam to C. H. Clark • Smokers warned of moocher\u27s smooth line; Inveterate victim lists defense tactics • IRC-PAC poll gives student views on foreign policy • Mr. Morrison invents zipped turkey; Facilitates the filling of the fowl • Library adds books by American authors • Major Bowen advocates aid to Chiang, says nationalists now ready and able • Dave Reice elected basketball captain • Christensen ends managerial career; Fisher carries on • Garnet downs Delaware to capture league title • Belles gain fifth victory as Vadner scores twenty • Ursinus swimmers beat Beaver mermaids, 34-23 • Fischer and Lintner elected to guide Bruins on grid during \u2751-\u2752 campaign • Baseball squad enters 2nd week of practice • Brodbeck teams lead men\u27s intramural loop • Schedules listed for track, tennis • Seven wrestlers lost by graduation; Basketball squad loses four regulars • Badminton team splits with Drexel, Bryn Mawrhttps://digitalcommons.ursinus.edu/weekly/1562/thumbnail.jp