On Narrowing the Scientific Knowledge Gap

It is now several years since the scientific knowledge gap was pointed out clearly by C. P. Snow in his Two Cultures

Valuing the Student Voice: Student Observer/Consultant Programs

This article discusses student observer/consultant programs which train impartial students who are invited to give feedback to faculty participants on their teaching. These programs are one way to value the student voice in faculty development. An overview and brief analysis of student observer/consultant programs and evaluations by participants are provided

Valuing the Student Voice: Student Observer/Consultant Programs

This article discusses student observer/consultant programs which train impartial students who are invited to give feedback to faculty participants on their teaching. These programs are one way to value the student voice in faculty development. An overview and brief analysis of student observer/consultant programs and evaluations by participants are provided

Buoyant Venus station feasibility study. Volume IV - Communications and power Final report

Telecommunication and power supply requirements for inflatable buoyant Venus statio

Internal and external axial corner flows

The inviscid, internal, and external axial corner flows generated by two intersecting wedges traveling supersonically are obtained by use of a second-order shock-capturing, finite-difference approach. The governing equations are solved iteratively in conical coordinates to yield the complicated wave structure of the internal corner and the simple peripheral shock of the external corner. The numerical results for the internal flows compare favorably with existing experimental data

A SINGLE ANCIENT ORIGIN OF BROOD PARASITISM IN AFRICAN FINCHES: IMPLICATIONS FOR HOST-PARASITE COEVOLUTION

. Robust phylogenies for brood-parasitic birds, their hosts, and nearest nesting relatives provide the framework to address historical questions about host-parasite coevolution and the origins of parasitic behavior. We tested phylogenetic hypotheses for the two genera of African brood-parasitic finches, Anomalospiza and Vidua , using mitochondrial DNA sequence data from 43 passeriform species. Our analyses strongly support a sister relationship between Vidua and Anomalospiza , leading to the conclusion that obligate brood parasitism evolved only once in African finches rather than twice, as has been the conventional view. In addition, the parasitic finches (Viduidae) are not recently derived from either weavers (Ploceidae) or grassfinches (Estrildidae), but represent a third distinct lineage. Among these three groups, the parasitic finches and estrildids, which includes the hosts of all 19 Vidua species, are sister taxa in all analyses of our full dataset. Many characters shared by Vidua and estrildids, including elaborate mouth markings in nestlings, unusual begging behavior, and immaculate white eggs, can therefore be attributed to common ancestry rather than convergent evolution. The host-specificity of mouth mimicry in Vidua species, however, is clearly the product of subsequent host-parasite coevolution. The lineage leading to Anomalospiza switched to parasitizing more distantly related Old World warblers (Sylviidae) and subsequently lost these characteristics. Substantial sequence divergence between Vidua and Anomalospiza indicates that the origin of parasitic behavior in this clade is ancient (∼20 million years ago), a striking contrast to the recent radiation of extant Vidua . We suggest that the parasitic finch lineage has experienced repeated cycles of host colonization, speciation, and extinction through their long history as brood parasites and that extant Vidua species represent only the latest iterations of this process. This dynamic process may account for a significantly faster rate of DNA sequence evolution in parasitic finches as compared to estrildids and other passerines. Our study reduces by one the tally of avian lineages in which obligate brood parasitism has evolved and suggests an origin of parasitism that involved relatively closely related species likely to accept and provide appropriate care to parasitic young. Given the ancient origin of parasitism in African finches, ancestral estrildids must have been parasitized well before the diversification of extant Vidua , suggesting a long history of coevolution between these lineages preceding more recent interactions between specific hosts and parasites.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72018/1/j.0014-3820.2001.tb00768.x.pd

Environmental Effects on Limit-Fed Feedlot Finishing Diets

Ninety-six crossbred yearling steers were allotted to either ad libitum or 93% of ad libitum intake treatments in a 117-day winter finishing trial. Intake restriction began once the 93% treatment group was started on its finishing diet. Finishing diets were formulated to result in similar absolute intakes of nutrients and feed additives. Restricted treatment dry matter intake was lower than ad libitum as intended (P\u3c.05), but average daily gain was also less, 3.71 and 3.50 Ib per day (P\u3c.05) and resulted in similar feed/gain, 6.01 and 6.07 (P\u3e.82). These results are in contrast to two previous trials conducted during summer and mild winter/spring conditions and suggest that cold stress may affect the response to limit-feeding of feedlot finishing diets

Laser-induced plasma generation of terahertz radiation using three incommensurate wavelengths

We present the generation of THz radiation by focusing ultrafast laser pulses with three incommensurate wavelengths to form a plasma. The three colors include 800 nm and the variable IR signal and idler outputs from an optical parametric amplifier. We observe that stable THz is generated when all three colors are present, with a peak-to-peak field strength of ~200 kV cm^(−1) and a relatively broad, smooth spectrum extending out to 6 THz, without any strong dependence on the selection of signal and idler IR wavelengths (in the range from 1300 to 2000 nm). We confirm that three colors are indeed needed, and we present plasma current modeling that corroborates our observations