521 research outputs found
Protein futures for Western Europe: potential land use and climate impacts in 2050
Multiple production and demand side measures are needed to improve food system sustainability. This study quantified the theoretical minimum agricultural land requirements to supply Western Europe with food in 2050 from its own land base, together with GHG emissions arising. Assuming that crop yield gaps in agriculture are closed, livestock production efficiencies increased and waste at all stages reduced, a range of food consumption scenarios were modelled each based on different ‘protein futures’. The scenarios were as follows: intensive and efficient livestock production using today’s species mix; intensive efficient poultry–dairy production; intensive efficient aquaculture–dairy; artificial meat and dairy; livestock on ‘ecological leftovers’ (livestock reared only on land unsuited to cropping, agricultural residues and food waste, with consumption capped at that level of availability); and a ‘plant-based eating’ scenario. For each scenario, ‘projected diet’ and ‘healthy diet’ variants were modelled. Finally, we quantified the theoretical maximum carbon sequestration potential from afforestation of spared agricultural land. Results indicate that land use could be cut by 14–86 % and GHG emissions reduced by up to approximately 90 %. The yearly carbon storage potential arising from spared agricultural land ranged from 90 to 700 Mt CO2 in 2050. The artificial meat and plant-based scenarios achieved the greatest land use and GHG reductions and the greatest carbon sequestration potential. The ‘ecological leftover’ scenario required the least cropland as compared with the other meat-containing scenarios, but all available pasture was used, and GHG emissions were higher if meat consumption was not capped at healthy levels. 
First-principles calculations of the structural, electronic, vibrational and magnetic properties of C_{60} and C_{48}N_{12}: a comparative study
In this work, we perform first-principles calculations of the structural,
electronic, vibrational and magnetic properties of a novel azafullerene. Full geometrical optimization shows that is characterized by several distinguishing features: only
one nitrogen atom per pentagon, two nitrogen atoms preferentially sitting in
one hexagon, symmetry, 6 unique nitrogen-carbon and 9 unique
carbon-carbon bond lengths. The highest occupied molecular orbital of is a doubly degenerate level of symmetry and its
lowest unoccupied molecular orbital is a nondegenerate level of
symmetry. Vibrational frequency analysis predicts that has in total 116 vibrational modes: 58 infrared-active and 58
Raman-active modes. is also characterized by 8
and 2 NMR spectral signals. Compared to , shows an enhanced third-order optical
nonlinearities which implies potential applications in optical limiting and
photonics.Comment: a long version of our manuscript submitted to J.Chem.Phy
Terrestrial organic carbon storage in a British moorland
Accurate estimates for the size of terrestrial organic carbon (C) stores are needed to determine their importance in regulating atmospheric CO2 concentrations. The C stored in vegetation and soil components of a British moorland was evaluated in order to: (i) investigate the importance of these ecosystems for C storage and (ii) test the accuracy of the United Kingdom's terrestrial C inventory. The area of vegetation and soil types was determined using existing digitized maps and a Geographical Information System (GIS). The importance of evaluating C storage using 2D area projections, as opposed to true surface areas, was investigated and found to be largely insignificant. Vegetation C storage was estimated from published results of productivity studies at the site supplemented by field sampling to evaluate soil C storage. Vegetation was found to be much less important for C storage than soil, with peat soils, particularly Blanket bog, containing the greatest amounts of C. Whilst the total amount of C in vegetation was similar to the UK national C inventory's estimate for the same area, the national inventory estimate for soil C was over three times higher than the value derived in the current study. Because the UK's C inventory can be considered relatively accurate compared to many others, the results imply that current estimates for soil C storage, at national and global scales, should be treated with caution
Speciesistic Veganism: An Anthropocentric Argument
The paper proposes an anthropocentric argument for veganism based on a speciesistic premise that most carnists likely affirm: human flourishing should be promoted. I highlight four areas of human suffering promoted by a carnistic diet: (1) health dangers to workers (both physical and psychological), (2) economic dangers to workers, (3) physical dangers to communities around slaughterhouses, and (4) environmental dangers to communities-at-large. Consequently, one could ignore the well-being of non-human animals and nevertheless recognize significant moral failings in the current standard system of meat production
Gemini GMOS spectroscopy of HeII nebulae in M33
We have carried out a narrow-band survey of the Local Group galaxy, M33, in
the HeII4686 emission line, to identify HeII nebulae in this galaxy. With
spectroscopic follow-up observations, we confirm three of seven candidate
objects, including identification of two new HeII nebulae, BCLMP651, HBW673. We
also obtain spectra of associated ionizing stars for all the HII regions,
identifying two new WN stars. We demonstrate that the ionizing source for the
known HeII nebula, MA 1, is consistent with being the early-type WN star MC8
(M33-WR14), by carrying out a combined stellar and nebular analysis of MC8 and
MA1. We were unable to identify the helium ionizing sources for HBW 673 and
BCLMP 651, which do not appear to be Wolf-Rayet stars. According to the
[OIII]5007/Hbeta vs [NII]6584/Halpha diagnostic diagram, excitation mechanisms
apart from hot stellar continuum are needed to account for the nebular emission
in HBW 673, which appears to have no stellar source at all.Comment: Accepted for publication in Astronomy and Astrophysics. 22 pages, 10
figure
Physical Structure of Small Wolf-Rayet Ring Nebulae
We have selected the seven most well-defined WR ring nebulae in the LMC (Br
2, Br 10, Br 13, Br 40a, Br 48, Br 52, and Br 100) to study their physical
nature and evolutionary stages. New CCD imaging and echelle observations have
been obtained for five of these nebulae; previous photographic imaging and
echelle observations are available for the remaining two nebulae. Using the
nebular dynamics and abundances, we find that the Br 13 nebula is a
circumstellar bubble, and that the Br 2 nebula may represent a circumstellar
bubble merging with a fossil main-sequence interstellar bubble. The nebulae
around Br 10, Br 52, and Br 100 all show influence of the ambient interstellar
medium. Their regular expansion patterns suggest that they still contain
significant amounts of circumstellar material. Their nebular abundances would
be extremely interesting, as their central stars are WC5 and WN3-4 stars whose
nebular abundances have not been derived previously. Intriguing and tantalizing
implications are obtained from comparisons of the LMC WR ring nebulae with ring
nebulae around Galactic WR stars, Galactic LBVs, LMC LBVs, and LMC BSGs;
however, these implications may be limited by small-number statistics. A SNR
candidate close to Br 2 is diagnosed by its large expansion velocity and
nonthermal radio emission. There is no indication that Br 2's ring nebula
interacts dynamically with this SNR candidate.Comment: 20 pages, Latex (aaspp4.sty), 2 figures, accepted by the Astronomical
Journal (March 99 issue
Search for blue compact dwarf galaxies during quiescence II: metallicities of gas and stars, ages, and star-formation rates
We examine the metallicity and age of a large set of SDSS/DR6 galaxies that
may be Blue Compact Dwarf (BCD) galaxies during quiescence (QBCDs).The
individual spectra are first classified and then averaged to reduce noise. The
metallicity inferred from emission lines (tracing ionized gas) exceeds by ~0.35
dex the metallicity inferred from absorption lines (tracing stars). Such a
small difference is significant according to our error budget estimate. The
same procedure was applied to a reference sample of BCDs, and in this case the
two metallicities agree, being also consistent with the stellar metallicity in
QBCDs. Chemical evolution models indicate that the gas metallicity of QBCDs is
too high to be representative of the galaxy as a whole, but it can represent a
small fraction of the galactic gas, self enriched by previous starbursts. The
luminosity weighted stellar age of QBCDs spans the whole range between 1 and 10
Gyr, whereas it is always smaller than 1 Gyr for BCDs. Our stellar ages and
metallicities rely on a single stellar population spectrum fitting procedure,
which we have specifically developed for this work using the stellar library
MILES.Comment: Accepted for publication in ApJ. 20 pages. 16 figures (corrected
typos
Dapagliflozin-lowered blood glucose reduces respiratory Pseudomonas aeruginosa infection in diabetic mice.
BACKGROUND AND PURPOSE: Hyperglycaemia increases glucose concentrations in airway surface liquid and increases the risk of pulmonary Pseudomonas aeruginosa infection. We determined whether reduction of blood and airway glucose concentrations by the anti-diabetic drug dapagliflozin could reduce P. aeruginosa growth/survival in the lungs of diabetic mice. EXPERIMENTAL APPROACH: The effect of dapagliflozin on blood and airway glucose concentration, the inflammatory response and infection were investigated in C57BL/6J (wild type, WT) or leptin receptor-deficient (db/db) mice, treated orally with dapagliflozin prior to intranasal dosing with LPS or inoculation with P. aeruginosa. Pulmonary glucose transport and fluid absorption were investigated in Wistar rats using the perfused fluid-filled lung technique. KEY RESULTS: Fasting blood, airway glucose and lactate concentrations were elevated in the db/db mouse lung. LPS challenge increased inflammatory cells in bronchoalveolar lavage fluid from WT and db/db mice with and without dapagliflozin treatment. P. aeruginosa colony-forming units (CFU) were increased in db/db lungs. Pretreatment with dapagliflozin reduced blood and bronchoalveolar lavage glucose concentrations and P. aeruginosa CFU in db/db mice towards those seen in WT. Dapagliflozin had no adverse effects on the inflammatory response in the mouse or pulmonary glucose transport or fluid absorption in the rat lung. CONCLUSION AND IMPLICATIONS: Pharmacological lowering of blood glucose with dapagliflozin effectively reduced P. aeruginosa infection in the lungs of diabetic mice and had no adverse pulmonary effects in the rat. Dapagliflozin has potential to reduce the use, or augment the effect, of antimicrobials in the prevention or treatment of pulmonary infection
Using geographically weighted regression to explore the spatially heterogeneous spread of bovine tuberculosis in England and Wales
An understanding of the factors that affect the spread of endemic bovine tuberculosis (bTB) is critical for the development of measures to stop and reverse this spread. Analyses of spatial data need to account for the inherent spatial heterogeneity within the data, or else spatial autocorrelation can lead to an overestimate of the significance of variables. This study used three methods of analysis—least-squares linear regression with a spatial autocorrelation term, geographically weighted regression (GWR) and boosted regression tree (BRT) analysis—to identify the factors that influence the spread of endemic bTB at a local level in England and Wales. The linear regression and GWR methods demonstrated the importance of accounting for spatial differences in risk factors for bTB, and showed some consistency in the identification of certain factors related to flooding, disease history and the presence of multiple genotypes of bTB. This is the first attempt to explore the factors associated with the spread of endemic bTB in England and Wales using GWR. This technique improves on least-squares linear regression approaches by identifying regional differences in the factors associated with bTB spread. However, interpretation of these complex regional differences is difficult and the approach does not lend itself to predictive models which are likely to be of more value to policy makers. Methods such as BRT may be more suited to such a task. Here we have demonstrated that GWR and BRT can produce comparable outputs
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