792 research outputs found
Sharing responsibility for trade-related emissions based on economic benefits
Industrial Ecolog
The Tallest in the World: Native Americans of the Great Plains in the Nineteenth Century
Historians often portray Native Americans as merely unfortunate victims of European disease and aggression, with lives in disarray that followed the arrival of Columbus and other explorers or conquerors. The data we analyze on human stature show, in contrast, that some Native Americans such as the equestrian Plains nomads, were remarkably ingenious and adaptive in the face of exceptional demographic stress. Using anthropometric data originally collected by Franz Boas, we show that the Plains nomads were tallest in the world during the mid-nineteenth century. We link this extraordinary achievement to a rich and varied diet, modest disease loads other than epidemics, a remarkable facility at reorganization following demographic disasters, and egalitarian principles of operation. The analysis provides a useful mirror for understanding the health of Euro-Americans.
Evidence for the existence of powder sub-populations in micronized materials : Aerodynamic size-fractions of aerosolized powders possess distinct physicochemical properties
This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited.Purpose: To investigate the agglomeration behaviour of the fine ( 12.8 µm) particle fractions of salmeterol xinafoate (SX) and fluticasone propionate (FP) by isolating aerodynamic size fractions and characterising their physicochemical and re-dispersal properties. Methods: Aerodynamic fractionation was conducted using the Next Generation Impactor (NGI). Re-crystallized control particles, unfractionated and fractionated materials were characterized for particle size, morphology, crystallinity and surface energy. Re-dispersal of the particles was assessed using dry dispersion laser diffraction and NGI analysis. Results: Aerosolized SX and FP particles deposited in the NGI as agglomerates of consistent particle/agglomerate morphology. SX particles depositing on Stages 3 and 5 had higher total surface energy than unfractionated SX, with Stage 5 particles showing the greatest surface energy heterogeneity. FP fractions had comparable surface energy distributions and bulk crystallinity but differences in surface chemistry. SX fractions demonstrated higher bulk disorder than unfractionated and re-crystallized particles. Upon aerosolization, the fractions differed in their intrinsic emission and dispersion into a fine particle fraction (< 5.0 µm). Conclusions: Micronized powders consisted of sub-populations of particles displaying distinct physicochemical and powder dispersal properties compared to the unfractionated bulk material. This may have implications for the efficiency of inhaled drug deliveryPeer reviewe
Carbon supported CdSe nanocrystals
Insights to the mechanism of CdSe nanoparticle attachment to carbon nanotubes
following the hot injection method are discussed. It was observed that the
presence of water improves the nanotube coverage while Cl containing media are
responsible for the shape transformation of the nanoparticles and further
attachment to the carbon lattice. The experiments also show that the mechanism
taking place involves the right balance of several factors, namely, low
passivated nanoparticle surface, particles with well-defined crystallographic
facets, and interaction with an organics-free sp2 carbon lattice. Furthermore,
this procedure can be extended to cover graphene by quantum dots.Comment: 5 pages, 5 figure
Structural analysis of Pt(1 1 1)c(√3 × 5)rect.–CO using photoelectron diffraction
Core level shift scanned-energy mode photoelectron diffraction using the two distinct components of the C 1s emission has been used to determine the structure of the Pt(1 1 1)c(√3 × 5)rect.–CO phase formed by 0.6 ML of adsorbed CO. The results confirm earlier assignments of these components to CO in atop and bridging sites, further confirm that the best structural model involves a 2:1 occupation ratio of these two sites, and provides quantitative structural parameter values. In particular the Pt–C chemisorption bondlengths for the atop and bridging sites are, respectively, 1.86 ± 0.02 Å and 2.02 ± 0.04 Å. These values are closely similar to those found in the 0.5 ML coverage c(4 × 2) phase, involving an atop:bridge occupation ratio of 1:1, obtained in earlier quantitative low energy electron diffraction studies. The results also indicate a clear tilt of the molecular axis of atop CO species in this compression phase, consistent with the finding of an earlier electron-stimulated desorption ion angular distribution investigatio
On the Dynamics of the Evolution of the HIV Infection
We use a cellular automata model to study the evolution of HIV infection and
the onset of AIDS. The model takes into account the global features of the
immune response to any pathogen, the fast mutation rate of the HIV and a fair
amount of spatial localization. Our results reproduce quite well the
three-phase pattern observed in T cell and virus counts of infected patients,
namely, the primary response, the clinical latency period and the onset of
AIDS. We have also found that the infected cells may organize themselves into
special spatial structures since the primary infection, leading to a decrease
on the concentration of uninfected cells. Our results suggest that these cell
aggregations, which can be associated to syncytia, leads to AIDS.Comment: 4 pages, 3 postscript figure
The geographic mosaic of herbicide resistance evolution in the common morning glory, Ipomoea purpurea: Evidence for resistance hotspots and low genetic differentiation across the landscape
Strong human‐mediated selection via herbicide application in agroecosystems has repeatedly led to the evolution of resistance in weedy plants. Although resistance can occur among separate populations of a species across the landscape, the spatial scale of resistance in many weeds is often left unexamined. We assessed the potential that resistance to the herbicide glyphosate in the agricultural weed Ipomoea purpurea has evolved independently multiple times across its North American range. We examined both adaptive and neutral genetic variations in 44 populations of I. purpurea by pairing a replicated dose–response greenhouse experiment with SSR genotyping of experimental individuals. We uncovered a mosaic pattern of resistance across the landscape, with some populations exhibiting high‐survival postherbicide and other populations showing high death. SSR genotyping revealed little evidence of isolation by distance and very little neutral genetic structure associated with geography. An approximate Bayesian computation (ABC) analysis uncovered evidence for migration and admixture among populations before the widespread use of glyphosate rather than the very recent contemporary gene flow. The pattern of adaptive and neutral genetic variations indicates that resistance in this mixed‐mating weed species appears to have evolved in independent hotspots rather than through transmission of resistance alleles across the landscape.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/113156/1/eva12290_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/113156/2/eva12290.pd
Distributional impacts of carbon pricing in developing Asia
Understanding who would be affected in which way by carbon pricing is pivotal for effective and socially equitable policy design, addressing climate change and reducing inequality. This paper focuses on eight key countries in developing Asia (Bangladesh, India, Indonesia, Pakistan, Philippines, Thailand, Turkey and Vietnam). By combining national household surveys with input-output data, we compare the distributional effects of four carbon pricing design options, including a globally harmonized carbon price, a national carbon price and sectoral carbon prices in the power and transport sectors, respectively. Our analysis reveals a substantial degree of variation regarding who would be affected across policy designs and countries. Looking into national carbon pricing as the most favourable policy option from an economic point of view, we find that differences in distributional outcomes are generally more pronounced within income groups than across income groups. These differences are mainly driven by households' energy use patterns, which vary across countries. Equally recycling revenues back to all citizens would overcompensate the burden of a carbon price for the poorest households in all countries. Carbon pricing can alter income distribution. With a focus on Bangladesh, India, Indonesia, Pakistan, Philippines, Thailand, Turkey and Vietnam, this study compares four types of carbon pricing schemes and finds substantial variation in distributional effects across policy designs and countries.Industrial Ecolog
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