Morphological Variation, Karyology, and Systematic Relationships of \u3ci\u3eHeteromys gaumeri\u3c/i\u3e (Rodentia: Heteromyidae)

Morphological variation was assessed within and among populations of Heteromys gaumeri using univariate and multivariate statistical analyses of external and cranial measurements. Although patterns and amount of nongeographic variation in H. gaumeri were similar to other heteromyines, geographic variation was relatively conservative. Mean values of most characters were statistically homogeneous among localities and spatially unpatterned. Consequently, no association was found between levels of within- and among-sample variation for individual characters (the Kluge-Kerfoot phenomenon ). Populations of H. gaumeri were chromosomally monomorphic. The lack of morphological and chromosomal variation in H. gaumeri contrasts sharply with patterns in other heteromyines. Heteromys gaumeri is morphologically and chromosomally distinct from the H. desmarestianus species group (to which it is currently assigned) and appears to share some primitive characters with Liomys (the sister group of Heteromys). We recommend that H. gaumeri be removed from the H. desmarestianus group. Spanish abstract: La variación morfológica intra e interpoblacional de Heteromys gaumeri fue evaluada usando análisis estadísticos univariados y multivariados de medidas externas y craneales. A pesar de que los patrones y cantidad de variación intrapoblacional en H. gaumeri fue similar a la de otros heterominos, la variación geográfica fue relativamente conservadora. Los valores promedio de la mayoría de los caracteres fueron estadisticamente homogeneos entre las localidades, sin mostrar ningún patrón de variación espacial. En conservencia, no se encontró asociación alguna entre los niveles de variación intra e interpoblacional para caracteres individuates ( fenómena Kluge-Kerfoot ), Las poblaciones de H. gaumeri fueron monomórficas cromosómicamente. La falta de variacion tanto morfológica como cronosómica en H. gaumeri contrasta marcadamente con los patrones encontrados anteriormente para otros heteróminos. Heteromys gaumeri es morfológica y cromosómicamente distinguible del grupo H. desmarestianus (al cual se asigna actualmente) y aparentemente comparte algunos caracteres primitives con Liomys (el grupo hermano de Heteromys). Nosotros recomendamos que se remueva a H. gaumeri del grupo H. desmarestianus. Portuguese abstract: Avalia-se a variação morfológica intra- e interpopulacional de Heteromys gaumeri, através de análises estatisticas uni- e multivariadas de medidas externas e craniais. Apesar dos padrões, e da quantidade de variação intrapopulacional em H. gaumeri serem similares aos de outros heteromídeos, a variação geográfica é relativamente conservadora. Os valores médios da maior parte dos caráteres examinados são estatìsticamente homogeneos entre as localidades, e não surgiu nenhum padrão de variações locais. Consequentemente, não foram encontradas assoçiacões entre os níveis de varaiações intra- e interpopulacionais para caráteres individuais (o “fenômeno Kluge-Kerfoot”). Populações de H. gaumeri mostraram-se cromossômicamente monomórficas. A falta de variação morfológica ou cromossômica em H. gaumeri é altamente contrastante aos padrões encontrados em outros heteromídeos. Heteromys gaumeri distinguese tanto morfológica quanto cromossômicamente do grupo H. desmarestianus, ao qual está atualmente designado, e aparentemente possue caráteres primitivos em comum com Liomys—grupo irmão de Heteromys. Recomendamos que H. gaumeri seja removido do grupo H. desmarestianus

Effects of Dissipation on Quantum Phase Slippage in Charge Density Wave Systems

We study the effect of the dissipation on the quantum phase slippage via the creation of ``vortex ring'' in charge density wave (CDW) systems. The dissipation is assumed to come from the interaction with the normal electron near and inside of the vortex core. We describe the CDW by extracted macroscopic degrees of freedom, that is, the CDW phase and the radius of the ``vortex ring'', assume the ohmic dissipation, and investigate the effect in the context of semiclassical approximation. The obtained results are discussed in comparison with experiments. It turns out that the effect of such a dissipation can be neglected in experiments.Comment: 9 pages (revtex), 2 figures, using epsf.st

Study of filtration mechanics and sampling techniques, phase II Technical summary report, 1 Jan. - 31 Dec. 1965

Contaminant capacity at constant flow rate of pleated wire cloth filter element for testing wide range of silica impuritie

Study of filtration mechanics and sampling techniques technical summary report, 1 sep. 1963 - 30 nov. 1964

Filtration mechanics and sampling technique

Pressure of thermal excitations in superfluid helium

We find the pressure, due to the thermal excitations of superfluid helium, at the interface with a solid. The separate contributions of phonons, $R^-$ rotons and $R^+$ rotons are derived. The pressure due to $R^-$ rotons is shown to be negative and partially compensates the positive contribution of $R^+$ rotons, so the total roton pressure is positive but several times less than the separate $R^-$ and $R^+$ roton contributions. The pressure of the quasiparticle gas is shown to account for the fountain effect in $HeI I$. An experiment is proposed to observe the negative pressure due to $R^-$ rotons.Comment: 14 pages, 4 figure

Patterns of differential introgression in a salamander hybrid zone: inferences from genetic data and ecological niche modelling

Hybrid zones have yielded considerable insight into many evolutionary processes, including speciation and the maintenance of species boundaries. Presented here are analyses from a hybrid zone that occurs among three salamanders – Plethodon jordani , Plethodon metcalfi and Plethodon teyahalee – from the southern Appalachian Mountains. Using a novel statistical approach for analysis of non-clinal, multispecies hybrid zones, we examined spatial patterns of variation at four markers: single-nucleotide polymorphisms (SNPs) located in the mtDNA ND2 gene and the nuclear DNA ILF3 gene, and the morphological markers of red cheek pigmentation and white flecks. Concordance of the ILF3 marker and both morphological markers across four transects is observed. In three of the four transects, however, the pattern of mtDNA is discordant from all other markers, with a higher representation of P. metcalfi mtDNA in the northern and lower elevation localities than is expected given the ILF3 marker and morphology. To explore whether climate plays a role in the position of the hybrid zone, we created ecological niche models for P. jordani and P. metcalfi . Modelling results suggest that hybrid zone position is not determined by steep gradients in climatic suitability for either species. Instead, the hybrid zone lies in a climatically homogenous region that is broadly suitable for both P. jordani and P. metcalfi . We discuss various selective (natural selection associated with climate) and behavioural processes (sex-biased dispersal, asymmetric reproductive isolation) that might explain the discordance in the extent to which mtDNA and nuclear DNA and colour-pattern traits have moved across this hybrid zone.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/79135/1/j.1365-294X.2010.04796.x.pd

A Systematic Search for High Surface Brightness Giant Arcs in a Sloan Digital Sky Survey Cluster Sample

We present the results of a search for gravitationally-lensed giant arcs conducted on a sample of 825 SDSS galaxy clusters. Both a visual inspection of the images and an automated search were performed and no arcs were found. This result is used to set an upper limit on the arc probability per cluster. We present selection functions for our survey, in the form of arc detection efficiency curves plotted as functions of arc parameters, both for the visual inspection and the automated search. The selection function is such that we are sensitive only to long, high surface brightness arcs with g-band surface brightness mu_g 10. Our upper limits on the arc probability are compatible with previous arc searches. Lastly, we report on a serendipitous discovery of a giant arc in the SDSS data, known inside the SDSS Collaboration as Hall's arc.Comment: 34 pages,8 Fig. Accepted ApJ:Jan-200

Horizontal transfer of methoprene in Tribolium castaneum

Aerosol applications of reduced risk insecticides such as pyrethrins, pyrethroids, and insect growth regulators are becoming more commonly used to manage stored-product insects in food facilities. However, these applications have a limited ability to penetrate into hidden refugia, where the majority of the pest population is located. Horizontal transfer of insecticides could occur as individuals directly treated or exposed to treated surfaces move into hidden refugia and encounter untreated individuals. In this series of studies, the potential for horizontal transfer of methoprene from treated Tribolium castaneum , the red flour beetle, to untreated individuals was evaluated. Adding larvae, pupae, or adults treated with methoprene to flour patches with untreated T. castaneum larvae, resulted in increased pupa and adult deformities and higher numbers of dead focal individuals, which suggests the potential for this mechanism. The transfer mechanism might be flour substrate contamination, transfer during contact of individuals, and/or cannibalism of individuals exposed to insecticides. Experiments focused on isolating the impact of contact and cannibalism on horizontal transfer did not detect a significant increase in mortality. Experiments focused on flour substrate contamination resulted in decreased adult emergence as well as lower survival, and higher rates of deformities. These findings suggest that substrate contamination is the more likely mechanism for horizontal transfer, and although horizontal transfer can occur, the impact of this process on populations needs further evaluation. Keywords: Red flour beetle, Tribolium castaneum, Methoprene, Horizontal transfe