278 research outputs found
Multi-criteria assessment of household preferences for reducing greenhouse gas emissions: an analysis of household survey data from four European cities
In a study of households living in mid-size cities in France, Germany, Norway and Sweden we assessed preferences (among 65 possible actions) for reducing greenhouse gas (GHG) emissions. Each GHG reduction action was compared in terms of three objective criteria â CO2e emissions, health impact and cost â using scores which gave alternative priority weightings to each. The multi-criteria scores were then compared with the proportion of respondents declaring their willingness to implement each action. Actions that respondents were often willing to implement and scored highly on the three assessment criteria included measures with likely ancillary benefits for health such as eating 30% more vegetarian food, walking and cycling instead of using public transport, and improvements of roof and window insulation. Although most householders appeared willing to make appreciable changes to their lifestyle and home in order to help achieve GHG emissions reductions, relatively few signaled their willingness to adopt major changes, such as becoming entirely vegetarian or giving up use of the car, even if there were appreciable health benefits. The evidence of these analyses provides insights into household preferences for actions that may help achieve important mitigation and health benefits
Electric-field-induced coherent coupling of the exciton states in a single quantum dot
The signature of coherent coupling between two quantum states is an
anticrossing in their energies as one is swept through the other. In single
semiconductor quantum dots containing an electron-hole pair the eigenstates
form a two-level system that can be used to demonstrate quantum effects in the
solid state, but in all previous work these states were independent. Here we
describe a technique to control the energetic splitting of these states using a
vertical electric field, facilitating the observation of coherent coupling
between them. Near the minimum splitting the eigenstates rotate in the plane of
the sample, being orientated at 45{\deg} when the splitting is smallest. Using
this system we show direct control over the exciton states in one quantum dot,
leading to the generation of entangled photon pairs
Effect of the GaAsP shell on optical properties of self-catalyzed GaAs nanowires grown on silicon
We realize growth of self-catalyzed core-shell GaAs/GaAsP nanowires (NWs) on
Si substrates using molecular-beam epitaxy. Transmission electron microscopy
(TEM) of single GaAs/GaAsP NWs confirms their high crystal quality and shows
domination of the zinc-blende phase. This is further confirmed in optics of
single NWs, studied using cw and time-resolved photoluminescence (PL). A
detailed comparison with uncapped GaAs NWs emphasizes the effect of the GaAsP
capping in suppressing the non-radiative surface states: significant PL
enhancement in the core-shell structures exceeding 2000 times at 10K is
observed; in uncapped NWs PL is quenched at 60K whereas single core-shell
GaAs/GaAsP NWs exhibit bright emission even at room temperature. From analysis
of the PL temperature dependence in both types of NW we are able to determine
the main carrier escape mechanisms leading to the PL quench
Temporal deconvolution of vascular plant-derived fatty acids exported from terrestrial watersheds
Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 244 (2019): 502-521, doi:10.1016/j.gca.2018.09.034.Relatively little is known about the amount of time that lapses between the
photosynthetic fixation of carbon by vascular land plants and its incorporation into the
marine sedimentary record, yet the dynamics of terrestrial carbon sequestration have
important implications for the carbon cycle. Vascular plant carbon may encounter
multiple potential intermediate storage pools and transport trajectories, and the age of
vascular plant carbon accumulating in marine sediments will reflect these different predepositional
histories. Here, we examine down-core 14C profiles of higher plant leaf waxderived
fatty acids isolated from high fidelity sedimentary sequences spanning the socalled
âbomb-spikeâ, and encompassing a ca. 60-degree latitudinal gradient from tropical
(Cariaco Basin), temperate (Saanich Inlet), and polar (Mackenzie Delta) watersheds to
constrain integrated vascular plant carbon storage/transport times (âresidence timesâ).
Using a modeling framework, we find that, in addition to a "young" (conditionally
defined as < 50 y) carbon pool, an old pool of compounds comprises 49 to 78 % of the
fractional contribution of organic carbon (OC) and exhibits variable ages reflective of the
environmental setting. For the Mackenzie Delta sediments, we find a mean age of the old
pool of 28 ky (±9.4, standard deviation), indicating extensive pre-aging in permafrost
soils, whereas the old pools in Saanich Inlet and Cariaco Basin sediments are younger,
7.9 (±5.0) and 2.4 (±0.50) to 3.2 (±0.54) ky, respectively, indicating less protracted
storage in terrestrial reservoirs. The "young" pool showed clear annual contributions for
Saanich Inlet and Mackenzie Delta sediments (comprising 24% and 16% of this pool,
respectively), likely reflecting episodic transport of OC from steep hillside slopes
surrounding Saanich Inlet and annual spring flood deposition in the Mackenzie Delta,
respectively. Contributions of 5-10 year old OC to the Cariaco Basin show a short delay
of OC inflow, potentially related to transport time to the offshore basin. Modeling results
also indicate that the Mackenzie Delta has an influx of young but decadal material (20-30
years of age), pointing to the presence of an intermediate reservoir.
Overall, these results show that a significant fraction of vascular plant C
undergoes pre-aging in terrestrial reservoirs prior to accumulation in deltaic and marine
sediments. The age distribution, reflecting both storage and transport times, likely
depends on landscape-specific factors such as local topography, hydrographic characteristics, and mean annual temperature of the catchment, all of which affect the
degree of soil buildup and preservation. We show that catchment-specific carbon
residence times across landscapes can vary by an order of magnitude, with important
implications both for carbon cycle studies and for the interpretation of molecular
terrestrial paleoclimate records preserved in sedimentary sequences.Financial support was provided by a Schlanger Ocean
Drilling Graduate Fellowship (NJD), an EPA STAR Graduate Fellowship (NJD), a Dutch
NWO Veni grant #825.10.022 (JEV), US NSF grants #OCE-0137005 (TIE and KAH),
#OCE-052626800 (TIE), #OCE-0961980 (ERMD), and #EAR-0447323 (ERMD and
JRS), a Swiss SNF grant #200021_140850 (TIE), a Swedish Research Council grant
#2013-05204 (MS), as well as the Stanley Watson Chair for Excellence in Oceanography
at WHOI (TIE) and the WHOI Arctic Research Initiative (TIE and LG)
Temporal deconvolution of vascular plant-derived fatty acids exported from terrestrial watersheds
Relatively little is known about the amount of time that lapses between the photosynthetic fixation of carbon by vascular land plants and its incorporation into the marine sedimentary record, yet the dynamics of terrestrial carbon sequestration have important implications for the carbon cycle. Vascular plant carbon may encounter multiple potential intermediate storage pools and transport trajectories, and the age of vascular plant carbon accumulating in marine sediments will reflect these different pre-depositional histories. Here, we examine down-core 14C profiles of higher plant leaf wax-derived fatty acids isolated from high fidelity sedimentary sequences spanning the so-called âbomb-spikeâ, and encompassing a ca. 60-degree latitudinal gradient from tropical (Cariaco Basin), temperate (Saanich Inlet), and polar (Mackenzie Delta) watersheds to constrain integrated vascular plant carbon storage/transport times (âresidence timesâ).
Using a modeling framework, we find that, in addition to a "young" (conditionally defined as < 50 y) carbon pool, an old pool of compounds comprises 49 to 78 % of the fractional contribution of organic carbon (OC) and exhibits variable ages reflective of the environmental setting. For the Mackenzie Delta sediments, we find a mean age of the old pool of 28 ky (±9.4, standard deviation), indicating extensive pre-aging in permafrost soils, whereas the old pools in Saanich Inlet and Cariaco Basin sediments are younger, 7.9 (±5.0) and 2.4 (±0.50) to 3.2 (±0.54) ky, respectively, indicating less protracted storage in terrestrial reservoirs. The "young" pool showed clear annual contributions for Saanich Inlet and Mackenzie Delta sediments (comprising 24% and 16% of this pool, respectively), likely reflecting episodic transport of OC from steep hillside slopes surrounding Saanich Inlet and annual spring flood deposition in the Mackenzie Delta, respectively. Contributions of 5-10 year old OC to the Cariaco Basin show a short delay of OC inflow, potentially related to transport time to the offshore basin. Modeling results also indicate that the Mackenzie Delta has an influx of young but decadal material (20-30 years of age), pointing to the presence of an intermediate reservoir.
Overall, these results show that a significant fraction of vascular plant C undergoes pre-aging in terrestrial reservoirs prior to accumulation in deltaic and marine sediments. The age distribution, reflecting both storage and transport times, likely depends on landscape-specific factors such as local topography, hydrographic characteristics, and mean annual temperature of the catchment, all of which affect the degree of soil buildup and preservation. We show that catchment-specific carbon residence times across landscapes can vary by an order of magnitude, with important implications both for carbon cycle studies and for the interpretation of molecular terrestrial paleoclimate records preserved in sedimentary sequences
Long telomeres are associated with clonality in wild populations of the fissiparous starfish Coscinasterias tenuispina
7 pĂĄginas, 4 figuras, 3 tablasTelomeres usually shorten during an organismâs lifespan and have thus been used as an aging and health marker. When
telomeres become sufficiently short, senescence is induced. The most common method of restoring telomere length is via
telomerase reverse transcriptase activity, highly expressed during embryogenesis. However, although asexual reproduction from
adult tissues has an important role in the life cycles of certain species, its effect on the aging and fitness of wild populations,
as well as its implications for the long-term survival of populations with limited genetic variation, is largely unknown. Here we
compare relative telomere length of 58 individuals from four populations of the asexually reproducing starfish Coscinasterias
tenuispina. Additionally, 12 individuals were used to compare telomere lengths in regenerating and non-regenerating arms, in
two different tissues (tube feet and pyloric cecum). The level of clonality was assessed by genotyping the populations based on
12 specific microsatellite loci and relative telomere length was measured via quantitative PCR. The results revealed significantly
longer telomeres in Mediterranean populations than Atlantic ones as demonstrated by the KruskalâWallis test (K=24.17,
significant value: P-valueo0.001), with the former also characterized by higher levels of clonality derived from asexual
reproduction. Telomeres were furthermore significantly longer in regenerating arms than in non-regenerating arms within
individuals (pyloric cecum tissue: MannâWhitney test, V=299, P-valueo10â 6; and tube feet tissue Student's t= 2.28,
P-value =0.029). Our study suggests that one of the mechanisms responsible for the long-term somatic maintenance and
persistence of clonal populations is telomere elongation.This research was financially supported by a
PhD fellowship FPI-MICINN (BES-2011-044154) (ACG), the European
ASSEMBLY project (227799), the Swedish Royal Academy of Sciences (ACG)
and the Spanish Government project CTM2010-22218-C02. The research was
also supported by a âJuan de la Ciervaâ contract from the Spanish Government
(RPP) and by the Adlerbertska Research Foundation (HNS).Peer reviewe
Household Preferences to Reduce Their Greenhouse Gas Footprint: A Comparative Study from Four European Cities
This paper investigates householdsâ preferences to reduce their carbon footprint (CF) measured in carbon dioxide equivalents (COâe). It assumes that a substantial CF reduction of households is essential to reach the 1.5 °C goal under the Paris Agreement. Data was collected in four mid-size cities in France, Germany, Norway, and Sweden. Quantitative data was obtained from 308 households using a CF calculator based on a questionnaire, and a simulation game. The latter investigated householdsâ preferences when being confronted with the objective to reduce their CF by 50 percent by 2030 in a voluntary and forced scenario. Our results show that the greater the COâe-reduction potential of a mitigation action, the less willing a household was to implement that action. Households preferred actions with moderate lifestyle changes foremost in the food sector. Voluntarily, households reached a 25% footprint reduction by 2030. To reach a substantial reduction of 50 percent, households needed to choose actions that meant considerable lifestyle changes, mainly related to mobility. Given our results, the 1.5 °C goal is unlikely to be realizable currently, unless households receive major policy support. Lastly, the strikingly similar preferences of households in the four European cities investigated seem to justify strong EU and international policies
Rational design of HIV vaccine and microbicides: report of the EUROPRISE annual conference
EUROPRISE is a Network of Excellence sponsored from 2007 to 2011 by the European Commission within the 6th Framework Program. The Network encompasses a wide portfolio of activities ranging from an integrated research program in the field of HIV vaccines and microbicides to training, dissemination and advocacy. The research program covers the whole pipeline of vaccine and microbicide development from discovery to early clinical trials. The Network is composed of 58 partners representing more than 65 institutions from 13 European countries; it also includes three major pharmaceutical companies (GlaxoSmithKline, Novartis and Sanofi-Pasteur) involved in HIV microbicide and vaccine research. The Network displays a dedicated and informative web page: http://www.europrise.org. Finally, a distinguishing trait of EUROPRISE is its PhD School of students from across Europe, a unique example in the world of science aimed at spreading excellence through training
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