Unified dark energy thermodynamics: varying w and the -1-crossing

We investigate, in a unified and general way, the thermodynamic properties of dark energy with an arbitrary, varying equation-of-state parameter w(a). We find that all quantities are well defined and regular for every w(a), including at the -1-crossing, with the temperature being negative in the phantom regime (w(a)-1). The density and entropy are always positive while the chemical potential can be arbitrary. At the -1-crossing, both temperature and chemical potential are zero. The temperature negativity can only be interpreted in the quantum framework. The regular behavior of all quantities at the -1-crossing, leads to the conclusion that such a crossing does not correspond to a phase transition, but rather to a smooth cross-over.Comment: 5 pages, version published in Class. Quant. Gra

Influenza A Viruses from Wild Birds in Guatemala Belong to the North American Lineage

The role wild bird species play in the transmission and ecology of avian influenza virus (AIV) is well established; however, there are significant gaps in our understanding of the worldwide distribution of these viruses, specifically about the prevalence and/or significance of AIV in Central and South America. As part of an assessment of the ecology of AIV in Guatemala, we conducted active surveillance in wild birds on the Pacific and Atlantic coasts. Cloacal and tracheal swab samples taken from resident and migratory wild birds were collected from February 2007 to January 2010.1913 samples were collected and virus was detected by real time RT-PCR (rRT-PCR) in 28 swab samples from ducks (Anas discors). Virus isolation was attempted for these positive samples, and 15 isolates were obtained from the migratory duck species Blue-winged teal. The subtypes identified included H7N9, H11N2, H3N8, H5N3, H8N4, and H5N4. Phylogenetic analysis of the viral sequences revealed that AIV isolates are highly similar to viruses from the North American lineage suggesting that bird migration dictates the ecology of these viruses in the Guatemalan bird population

Avifauna de Campo Morado, Guerrero, México Avifauna of Campo Morado, Guerrero, Mexico

Se presenta una lista de 124 especies de aves para la región de Campo Morado, Guerrero, México, con información sobre el estatus estacional, categoría de riesgo y endemismo. Se resaltan 15 registros sobresalientes, ya sea porque son nuevos para el estado, o porque amplían su distribución geográfica y/o modifican su distribución estacional conocida. Además se discute la importancia de la localidad dentro de la cuenca del río Balsas.We report a list of 124 bird species from Campo Morado, Guerrero, Mexico, with information on seasonality, risk categories, and endemism. Fifteen records are noteworthy, as they are new state records, expand significantly their known geographical distribution, and/or modify their seasonal status within the area. We also highlight the importance of the study area within the Balsas River Basin

Infrared laser-induced chemistry of chlorodifluoromethane-silane mixtures at two irradiating wavelengths

Chemical reactions induced by single- and two-wavelength CO2 laser radiation in a mixture of silane and chlorodifluoromethane are initiated by the reaction between: CF2 and SiH4 and afford volatile carbonaceous products with C-H bonds, together with a solid deposit consisting of silicon carbide and highly reactive Si/C/H/F polymeric material. The results are in line with the reduction of the strong C-F bond of difluorocarbene and with the production of H2Si=CF2 silene as intermediate which undergoes dehydrofluorination and polymerization.Peer Reviewe

Abundance and habitat relationships of breeding birds in the Sky Islands and adjacent Sierra Madre Occidental of northwest Mexico

The Sierra Madre Occidental and neighboring Madrean Sky Islands span a large and biologically diverse region of northwest Mexico and portions of the southwestern United States. Little is known about the abundance and habitat use of breeding birds in this region of Mexico, but such information is important for guiding conservation and management. We assessed densities and habitat relationships of breeding birds across Sky Island mountain ranges in Mexico and adjacent portions of the Sierra Madre from 2009 to 2012. We estimated densities at multiple spatial scales, assessed variation in densities among all major montane vegetation communities, and identified and estimated the effects of important habitat attributes on local densities. Regional density estimates of 65% of 72 focal species varied significantly among eight montane vegetation communities that ranged from oak savannah and woodland at low elevations to pine and mixed-conifer forest at high elevations. Greater proportions of species occurred at peak densities or were relatively restricted to mixed-conifer forest and montane riparian vegetation likely because of higher levels of structural or floristic diversity in those communities, but those species were typically rare or uncommon in the Sky Islands. Fewer species had peak densities in oak and pine-oak woodland, and species associated with those communities were often more abundant across the region. Habitat models often included the effects of broadleaf deciduous vegetation cover (30% of species), which, together with tree density and fire severity, had positive effects on densities and suggest ways for managers to augment and conserve populations. Such patterns combined with greater threats to high-elevation conifer forest and riparian areas underscore their value for conservation. Significant populations of many breeding bird species, including some that are of concern or were not known to occur regionally or in mountain ranges we surveyed, highlight the importance of conservation efforts in this area of Mexico.National Park Service; Desert Southwest Cooperative Ecosystem Studies Unit; U.S. Fish and Wildlife Service; Sky Island Alliance; Veolia Environment Foundation; University of Montana Graduate School12 month embargoThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]