Population Responses of Microtus pennsylvanicus across a Chronological Sequence of Habitat Alteration

Author Institution: Dept of Biology, Muskingum College, New Concord, OHUnderstanding the effects of habitat alteration on population demography and persistence is emerging as one of the most important and challenging areas facing ecologists and conservation biologists today. Here we compare the population demography of a common but important consumer species in eastern and mid-western grassland communities (Microtus pennsylvanicus) across three habitats that differ in the amount of time since reclamation following strip-mining (30, 25, and 15 years). We established two 40 × 40 m plots at each of the three sites and used traditional capture-recapture techniques to monitor population size, survival, and recruitment through a nine-month period during 1999-2000. We predicted that populations of M. pennsylvanicus would exhibit higher population numbers, better survival rates, and higher rates of recruitment in habitat patches that had been recovering for longer periods of time. In contrast to our predictions, results indicated higher peak population numbers at the most recently disturbed site ( χ = 81.18 ± 9.59 individuals) and higher numbers of reproductive females ( χ = 3.38 ± 0.85) relative to sites recovering for 25 and 30 years ( χ peak population size = 28.08 ± 23.09 and 31.16 ± 1.75 individuals, respectively; χ number of reproductive females = 0.57 ± 0.32 and 1.13 ± 0.13, respectively). Thus it would appear that time since disturbance was not an important predictor of population performance for this species in this altered system. Alternative hypotheses such as the influence of local habitat attributes and population fluctuations are discussed

Parametrization of Electron-Impact Ionization Cross Sections from Laser-Excited and Aligned Atoms

A set of parameters describing electron-impact ionization from laser-aligned atoms are reported, which define the “length”, “width”, and “direction” of the quadruple differential cross section (QDCS) as a function of target alignment kB for fixed ingoing electron momentum k0 and outgoing momenta k1, k2. 24Mg was used, with k0, k1, k2, and kB in the same plane. The parameters are derived for a range of k2 angles, with k1 set at 30° to k0. The QDCS is then determined for all kB. The parameters are very angle sensitive, the QDCS direction varying more than 90° as the length to width ratio varied more than an order of magnitude

Responding to Foreign Competition: Overcoming Government Barriers

For a variety of reasons, governments erect barriers to international trade. In order to survive in the global marketplace, companies, therefore, need to overcome these barriers, whether by exporting, acquiring other firms, or entering strategic alliances with other businesses.https://openscholarship.wustl.edu/mlw_papers/1161/thumbnail.jp

Reconnaissance of infrared emission from the lunar nighttime surface

The reconnaissance described in this paper was performed in 1964 and is an extension and refinement of the first observations (1962), in the 8- to 14-μ wavelength region, of the thermal emission from the lunar nighttime surface [Murray and Wildey, 1964]. The present investigation was intended to sample representatively enough of the lunar surface to determine the general character of the lunar nighttime emission and the relative abundance of nighttime infrared anomalies. More complete studies of the infrared emission with higher spatial resolution during eclipse were made at about the same time [Saari and Shorthill, 1965]

Thermal infrared emission of the Jovian disk

The 8–14 micron infrared emission of Jupiter has been observed on six nights in December 1963 using the 200-inch Hale telescope. The new observations possess twice the resolution of those obtained in 1962. The brightness temperature at the center of the disk appears to be nearly constant at 129°K. With some slight ambiguity, the light bands are about 0.5° cooler in appearance than the dark bands. There is some suggestion of morning-evening asymmetry in one of the bands. The Great Red Spot is found to be from 1.5° to 2.0° cooler than the surrounding disk at the newer resolution