University of Wisconsin–Milwaukee

About: University of Wisconsin–Milwaukee is a education organization based out in Milwaukee, Wisconsin, United States. It is known for research contribution in the topics: Population & Gravitational wave. The organization has 11839 authors who have published 28034 publications receiving 936438 citations. The organization is also known as: UWM & University of Wisconsin-Milwaukee.

Dynamical mass ejection from binary neutron star mergers: Radiation-hydrodynamics study in general relativity

Abstract: We perform radiation-hydrodynamics simulations of binary neutron-star mergers in numerical relativity on the Japanese ``K'' supercomputer, taking into account neutrino cooling and heating by an updated leakage-plus-transfer scheme for the first time. Neutron stars are modeled by three modern finite-temperature equations of state (EOS) developed by Hempel and his collaborators. We find that the properties of the dynamical ejecta of the merger such as total mass, average electron fraction, and thermal energy depend strongly on the EOS. Only for a soft EOS (the so-called SFHo), the ejecta mass exceeds $0.01{M}_{\ensuremath{\bigodot}}$. In this case, the distribution of the electron fraction of the ejecta becomes broad due to the shock heating during the merger. These properties are well-suited for the production of the solar-like $r$-process abundance. For the other stiff EOS (DD2 and TM1), for which a long-lived massive neutron star is formed after the merger, the ejecta mass is smaller than $0.01{M}_{\ensuremath{\bigodot}}$, although broad electron-fraction distributions are achieved by the positron capture and the neutrino heating.

Colour polymorphism in birds: causes and functions

Abstract: We studied polymorphism in all species of birds that are presently known to show intraspecific variation in plumage colour. At least three main mechanisms have been put forward to explain the maintenance of polymorphism: apostatic, disruptive and sexual selection. All of them make partly different predictions. Our aims were to investigate evolutionary causes and adaptive functions of colour polymorphism by taking into account a number of ecological and morphological features of polymorphic species. Overall, we found 334 species showing colour polymorphism, which is 3.5% of all bird species. The occurrence of colour polymorphism was very high in Strigiformes, Ciconiiformes, Cuculiformes and Galliformes. Phylogenetically corrected analysis using independent contrasts revealed that colour polymorphism was maximally expressed in species showing a daily activity rhythm extended to day/night, living in both open and closed habitats. All these findings support the hypothesis that colour polymorphism probably evolved under selective pressures linked to bird detectability as affected by variable light conditions during activity period. Thus, we conclude that selective agents may be prey, predators and competitors, and that colour polymorphism in birds may be maintained by disruptive selection.

Evaluating the Effectiveness of Distance Learning: A Comparison Using Meta-Analysis

Abstract: This article uses meta-analysis to summarize the quantitative literature comparing the performance of students in distance education versus traditional classes. The average effect (average r = .048, k = 39, N = 71,731) demonstrates that distance education course students slightly outperformed traditional students on exams and course grades. The average effect was heterogeneous, and the examination of several moderating features (presence or absence of simultaneous interaction, type of channel used in distance education, and course substance) failed to produce a homogeneous solution. The results demonstrate, however, no clear decline in educational effectiveness when using distance education technology. The profound impact that technological innovations are having in all facets of education focuses attention on assessing relationships between changing modes and practices of instruction and their outcomes. The emergence of new technologies does not change the goals of education. The new technologies change the process of communication within an educational setting to accomplish those goals. Research by communication scholars is needed to examine how changes in means of communicating content impacts the goals of those engaged in a communication activity. Understanding potential impacts of technologically driven differences between traditional classrooms and distance learning contexts is clearly appropriate (Althaus, 1997; Boettcher, 1996; Greene & Meek, 1998; McHenry & Bozik, 1995; Verduin &