9,868 research outputs found
The Mr 28,000 gap junction proteins from rat heart and liver are different but related
The sequence of the amino-terminal 32 residues of the rat heart Mr 28,000 gap junction protein presented here allows, for the first time, a sequence comparison of gap junctional proteins from different tissues (heart and liver). Comparison of the rat heart gap junction protein sequence and that available from rat liver reveals 43% sequence identity and conservative changes at an additional 25% of the positions. Both proteins exhibit a hydrophobic domain which could represent a transmembrane span of the junction. This result unequivocally demonstrates the existence of at least two forms of the gap junction protein. As yet, no homology is evident between the gap junctional proteins of either heart or liver and main intrinsic protein from rat eye lens
Titan's atmosphere as observed by Cassini/VIMS solar occultations: CH, CO and evidence for CH absorption
We present an analysis of the VIMS solar occultations dataset, which allows
us to extract vertically resolved information on the characteristics of Titan's
atmosphere between 100-700 km with a characteristic vertical resolution of 10
km. After a series of data treatment procedures, 4 occultations out of 10 are
retained. This sample covers different seasons and latitudes of Titan. The
transmittances show clearly the evolution of the haze and detect the detached
layer at 310 km in Sept. 2011 at mid-northern latitudes. Through the inversion
of the transmission spectra with a line-by-line radiative transfer code we
retrieve the vertical distribution of CH and CO mixing ratio. The two
methane bands at 1.4 and 1.7 {\mu}m are always in good agreement and yield an
average stratospheric abundance of %. This is significantly less
than the value of 1.48% obtained by the GCMS/Huygens instrument. The analysis
of the residual spectra after the inversion shows that there are additional
absorptions which affect a great part of the VIMS wavelength range. We
attribute many of these additional bands to gaseous ethane, whose near-infrared
spectrum is not well modeled yet. Ethane contributes significantly to the
strong absorption between 3.2-3.5 {\mu}m that was previously attributed only to
C-H stretching bands from aerosols. Ethane bands may affect the surface windows
too, especially at 2.7 {\mu}m. Other residual bands are generated by stretching
modes of C-H, C-C and C-N bonds. In addition to the C-H stretch from aliphatic
hydrocarbons at 3.4 {\mu}m, we detect a strong and narrow absorption at 3.28
{\mu}m which we tentatively attribute to the presence of PAHs in the
stratosphere. C-C and C-N stretching bands are possibly present between 4.3-4.5
{\mu}m. Finally, we obtain the CO mixing ratio between 70-170 km. The average
result of ppm is in good agreement with previous studies.Comment: 51 pages, 28 figure
Investigating household recycling behaviour through the interactions between personal and situational factors
In recent years household recycling behaviour (HRB) has become a focal point in social science research to understand the concept of household waste recycling management. Household recycling systems involve two main actors: households and municipalities. This paper reports on an empirical study of the interaction between HRB and household waste recycling systems provided by municipalities. A convenience sample of 412 households was selected to complete a survey on recycling initiatives with personal and situational factors and also their interaction. Results showed that personal factors have a significant relation with situational factors (availability, accessibility, awareness and convenience) (p < 0.01) and vice versa; with a positive correlation (r (412) = +0.41). In addition, personal factors correlated positively to availability, accessibility, awareness and convenience at a p-value below 0.01. Furthermore, situational factors interact with demographical factors such that personal factors may be predicted (overall HRB). This study uses both an interdisciplinary and multi-methods approach to answer its research questions and is also accessible to both practitioner and academic domains. © 2014 WIT Press
Constraints on small-scale cosmological perturbations from gamma-ray searches for dark matter
Events like inflation or phase transitions can produce large density
perturbations on very small scales in the early Universe. Probes of small
scales are therefore useful for e.g. discriminating between inflationary
models. Until recently, the only such constraint came from non-observation of
primordial black holes (PBHs), associated with the largest perturbations.
Moderate-amplitude perturbations can collapse shortly after matter-radiation
equality to form ultracompact minihalos (UCMHs) of dark matter, in far greater
abundance than PBHs. If dark matter self-annihilates, UCMHs become excellent
targets for indirect detection. Here we discuss the gamma-ray fluxes expected
from UCMHs, the prospects of observing them with gamma-ray telescopes, and
limits upon the primordial power spectrum derived from their non-observation by
the Fermi Large Area Space Telescope.Comment: 4 pages, 3 figures. To appear in J Phys Conf Series (Proceedings of
TAUP 2011, Munich
Taking the measure of change: Predictive models of biodiversity change are required to inform conservation policy decisions
Over the past decade, numerous metrics for biodiversity—including species abundance, extinction risk, distribution, genetic variability, species turnover, and trait diversity—have been used to create indicators to track how biodiversity has changed (1–3). These indicators have made it clear that biodiversity loss, however it is measured, is showing little sign of abatement (1, 4) and that humans must respond to safeguard the provision of natural services on which we all rely (5, 6). But which metrics provide the most informative indicators under which circumstances? And how can the growing list of indicators best serve conservation policy decisions
Adaptation, Speciation, and Convergence: A Hierarchical Analysis of Adaptive Radiation in Caribbean Anolis Lizards
This is the publisher's version, also available electronically from http://www.bioone.org/doi/abs/10.3417/0026-6493%282006%2993%5B24%3AASACAH%5D2.0.CO%3B2.Caribbean Anolis lizards are a classic case of adaptive radiation, repeated four times across islands of the Greater Antilles. On each island, very similar patterns of evolutionary divergence have occurred, resulting in the evolution of the same set of ecological specialists—termed ecomorphs—on each island. However, this is only part of the story of the Caribbean anole radiations. Indeed, much of the species diversity of Caribbean Anolis occurs within clades of ecomorphs, which contain as many as 14 ecologically-similar species on a single island. We ask to what extent the classic model of ecological interactions as the driving force in adaptive radiation can account for this aspect of anole evolutionary diversity. Our answer is that it can in part, but not entirely. More generally, the most complete understanding of evolutionary diversification and radiation is achieved by studying multiple hierarchical evolutionary levels from clades to populations
Global biodiversity indicators reflect the modeled impacts of protected area policy change
Global biodiversity indicators can be used to measure the status and trends of biodiversity relating to Convention on Biological Diversity (CBD) targets. Whether such indicators can support decision makers by distinguishing among policy options remains poorly evaluated. We tested the ability of two CBD indicators, the Living Planet Index and the Red List Index, to reflect projected changes in mammalian populations in sub-Saharan Africa in response to potential policies related to CBD targets for protected areas (PAs). We compared policy scenarios to expand the PA network, improve management effectiveness of the existing network, and combinations of the two, against business as usual. Both indicators showed that more effective management would provide greater benefits to biodiversity than expanding PAs alone. The indicators were able to communicate outcomes of modeled scenarios in a simple quantitative manner, but behaved differently. This work highlights both the considerable potential of indicators in supporting decisions, and the need to understand how indicators will respond as biodiversity changes
Soil, Plant and Cattle Nutrient Dynamics on Pastures of the Western Amazon of Brazil
Cattle production on Brachiaria pastures is a primary use of cleared forestland in the western Brazilian Amazon. About 6.8 million hectares in the States of Acre and Rondônia have been deforested, where 75% of land is now grazed (IBGE, 1998). The principal pasture species are B. brizantha and B. decumbens with the latter in decline from spittlebug susceptibility (Deois incompleta; Gonçalves et al., 1996). The general pattern of pasture establishment in the Amazon basin includes felling and burning forest biomass, planting annual crops for one to three years (especially on small farms), and then seeding to grasses. The conversion of tropical forest to pasture, the effects of that process on soil properties, and pasture degradation outcomes have been studied in the eastern Amazon region ( Serrao et al., 1978; Reiners et al., 1994; Sanchez and Salinas, 1981; Buschbacher et al., 1987; Moraes et al., 1996) but not in the remote western region. Most findings showed an initial increase in soil cation concentrations with pasture establishment, except P, which declined to nearly undetectable amounts; and losses in pasture productivity after about five years with little management and poorly matched grasses (Serrao et al., 1978). The extent to which this outcome is due to poor management practices (e.g., inappropriate grass species) is unknown, and few studies in the region have examined the impacts of stocking rates, soil-plant nutrient relationships and burning frequencies on pasture degradation. Strategies that account for the cycling of major nutrients are needed to improve management of grasses and grass-legume associations. The objective of this study was to evaluate the hypothesis that low-input pasture use of land with Brachiaria spp. effectively sustains cattle production in the western Brazilian Amazon without deteriorating soil nutrient stocks . Three pasture land cover types (B. decumbens, B. brizantha and a grass association with Pueraria phaseoloides) were compared to primary forest and crops (maize and rice). Temporal (i.e., time post-deforestation) effects on the physical and chemical properties of soils and forages were evaluated. The nutrient pools in soil, plants and cattle herds and nutrients extracted in animal products were approximated to help understand the essential management to enhance cattle productivity and to avoid land degradation
- …