583 research outputs found
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Balancing competing policy demands: the case of sustainable public sector food procurement.
A focus on market-based green growth strategies to pursue sustainability goals neglects the pursuit of understanding how human health is interwoven with the health of eco-systems to deliver sustainability goals. The article argues that clarifying the difference between green and sustainable public sector food procurement, with political continuity that supports and enables policymakers and practitioners to take an incremental approach to change, makes an important contribution to delivering more sustainable food systems and better public health nutrition. Five European case studies demonstrate the reality of devising and implementing innovative approaches to sustainable public sector food procurement and the effects of cultural and political framings. How legislation is enacted at the national level and interpreted at the local level is a key driver for sustainable procurement. Transition is dependent on political will and leadership and an infrastructure that can balance the economic, environmental and social drivers to effect change. The development of systems and indicators to measure change, reforms to EU directives on procurement, and the relationship between green growth strategies and sustainable diets are also discussed. The findings show the need to explore how consistent definitions for green public procurement and sustainable public procurement can be refined and standardized in order to support governments at all levels in reviewing and analyzing their current food procurement strategies and practices to improve sustainability
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U.S. Department of Energy -- Advanced Vehicle Testing Activity: Plug-in Hybrid Electric Vehicle Testing and Demonstration Activities
The U.S. Department of Energyâs (DOE) Advanced Vehicle Testing Activity (AVTA) tests plug-in hybrid electric vehicles (PHEV) in closed track, dynamometer and onroad testing environments. The onroad testing includes the use of dedicated drivers on repeated urban and highway driving cycles that range from 10 to 200 miles, with recharging between each loop. Fleet demonstrations with onboard data collectors are also ongoing with PHEVs operating in several dozen states and Canadian Provinces, during which trips- and miles-per-charge, charging demand and energy profiles, and miles-per-gallon and miles-per-kilowatt-hour fuel use results are all documented, allowing an understanding of fuel use when vehicles are operated in charge depleting, charge sustaining, and mixed charge modes. The intent of the PHEV testing includes documenting the petroleum reduction potential of the PHEV concept, the infrastructure requirements, and operator recharging influences and profiles. As of May 2008, the AVTA has conducted track and dynamometer testing on six PHEV conversion models and fleet testing on 70 PHEVs representing nine PHEV conversion models. A total of 150 PHEVs will be in fleet testing by the end of 2008, all with onboard data loggers. The onroad testing to date has demonstrated 100+ miles per gallon results in mostly urban applications for approximately the first 40 miles of PHEV operations. The primary goal of the AVTA is to provide advanced technology vehicle performance benchmark data for technology modelers, research and development programs, and technology goal setters. The AVTA testing results also assist fleet managers in making informed vehicle purchase, deployment and operating decisions. The AVTA is part of DOEâs Vehicle Technologies Program. These AVTA testing activities are conducted by the Idaho National Laboratory and Electric Transportation Engineering Corporation, with Argonne National Laboratory providing dynamometer testing support. The proposed paper and presentation will discuss PHEV testing activities and results. INL/CON-08-1433
Logarithmic rate dependence in deforming granular materials
Rate-independence for stresses within a granular material is a basic tenet of
many models for slow dense granular flows. By contrast, logarithmic rate
dependence of stresses is found in solid-on-solid friction, in geological
settings, and elsewhere. In this work, we show that logarithmic rate-dependence
occurs in granular materials for plastic (irreversible) deformations that occur
during shearing but not for elastic (reversible) deformations, such as those
that occur under moderate repetitive compression. Increasing the shearing rate,
\Omega, leads to an increase in the stress and the stress fluctuations that at
least qualitatively resemble what occurs due to an increase in the density.
Increases in \Omega also lead to qualitative changes in the distributions of
stress build-up and relaxation events. If shearing is stopped at t=0, stress
relaxations occur with \sigma(t)/ \sigma(t=0) \simeq A \log(t/t_0). This
collective relaxation of the stress network over logarithmically long times
provides a mechanism for rate-dependent strengthening.Comment: 4 pages, 5 figures. RevTeX
Fault healing inferred from time dependent variations in source properties of repeating earthquakes
We analyze two sets of repeating earthquakes on the Calaveras fault to estimate in-situ rates of fault strengthening (healing). Earthquake recurrence intervals t, range from 3 to 803 days. Variations in relative moment and duration are combined to study changes in stress drop, rupture dimension, rupture velocity, and particle velocity as a function of tr. Healing rates and source variations are compared with predictions of laboratory derived friction laws. Two interpretations of event duration Ï are used: one in which Ï: is given by the ratio of slip to particle velocity and one in which it scales as rupture dimension divided by rupture velocity. Our data indicate that faults strengthen during the interseismic period. We infer that source dimension decreases with tr due to aseismic creep within the region surrounding the repeatinge vents. Stress drop increases 1-3MPa per decade increase in tr, which represents an increase of a factor of 2-3 relative to events with tr between 10 and 100 days. This rate of fault healing is consistent with extrapolations of laboratory measurements of healing rates if fault strength is high, on order of 60MPa, ands tress drop is roughly 10% of this value
The barium isotopic mixture for the metal-poor subgiant star HD140283
Current theory regarding heavy element nucleosynthesis in metal-poor
environments states that the r-process would be dominant. The star HD140283 has
been the subject of debate after it appeared in some studies to be dominated by
the s-process. We provide an independent measure of the Ba isotope mixture in
HD140283 using an extremely high quality spectrum and an extensive chi^2
analysis. We exploit hyperfine splitting of the BaII 4554 \AA\ and 4934 \AA\
resonance lines in an effort to constrain the isotope ratio in 1D LTE. Using
the code ATLAS in conjunction with KURUCZ06 model atmospheres we analyse 93 Fe
lines to determine the star's macroturbulence. With this information we
construct a grid of Ba synthetic spectra and, using a \chi^2 code, fit these to
our observed data to determine the isotopic ratio, fodd, which represents the
ratio of odd to even isotopes. We also analyse the Eu lines. We set a new upper
limit of the rotation of HD140283 at vsin{i}\leq3.9\kms, a new upper limit on
[Eu/H] < -2.80 and abundances [Fe/H] = -2.59\pm0.09, [Ba/H] = -3.46\pm0.11.
This leads to a new lower limit on [Ba/Eu] > -0.66. We find that, in the
framework of a 1D LTE analysis, the isotopic ratios of Ba in HD140283 indicate
fodd=0.02\pm0.06, a purely s-process signature. This implies that observations
and analysis do not validate currently accepted theory. We speculate that a 1D
code, due to simplifying assumptions, is not adequate when dealing with
observations with high levels of resolution and S/N because of the turbulent
motions associated with a 3D stellar atmosphere. New approaches to analysing
isotopic ratios, in particular 3D hydrodynamics, need to be considered when
dealing with the levels of detail required to properly determine them. However
published 3D results exacerbate the disagreement between theory and
observation.Comment: 16 pages, 10 figures, 7 tables, 1 online appendix Accepted by A&
Mechanisms for slow strengthening in granular materials
Several mechanisms cause a granular material to strengthen over time at low
applied stress. The strength is determined from the maximum frictional force
F_max experienced by a shearing plate in contact with wet or dry granular
material after the layer has been at rest for a waiting time \tau. The layer
strength increases roughly logarithmically with \tau -only- if a shear stress
is applied during the waiting time. The mechanisms of strengthening are
investigated by sensitive displacement measurements and by imaging of particle
motion in the shear zone. Granular matter can strengthen due to a slow shift in
the particle arrangement under shear stress. Humidity also leads to
strengthening, but is found not to be its sole cause. In addition to these time
dependent effects, the static friction coefficient can also be increased by
compaction of the granular material under some circumstances, and by cycling of
the applied shear stress.Comment: 21 pages, 11 figures, submitted to Phys. Rev.
Food security monitoring via mobile data collection and remote sensing: results from the Central African Republic
The Central African Republic is one of the world's most vulnerable countries, suffering from chronic poverty, violent conflicts and weak disaster resilience. In collaboration with Doctors without Borders/Midecins Sans Frontieres (MSF), this study presents a novel approach to collect information about socio-economic vulnerabilities related to malnutrition, access to resources and coping capacities. The first technical test was carried out in the North of the country (sub-prefecture Kabo) in May 2015. All activities were aimed at the investigation of technical feasibility, not at operational data collection, which requires a random sampling strategy. At the core of the study is an open-source Android application named SATIDA COLLECT that facilitates rapid and simple data collection. All assessments were carried out by local MSF staff after they had been trained for one day. Once a mobile network is available, all assessments can easily be uploaded to a database for further processing and trend analysis via MSF in-house software. On one hand, regularly updated food security assessments can complement traditional large-scale surveys, whose completion can take up to eight months. Ideally, this leads to a gain in time for disaster logistics. On the other hand, recording the location of every assessment via the smart phones. GPS receiver helps to analyze and display the coupling between drought risk and impacts over many years. Although the current situation in the Central African Republic is mostly related to violent conflict it is necessary to consider information about drought risk, because climatic shocks can further disrupt the already vulnerable system. SATIDA COLLECT can easily be adapted to local conditions or other applications, such as the evaluation of vaccination campaigns. Most importantly, it facilitates the standardized collection of information without pen and paper, as well as straightforward sharing of collected data with the MSF headquarters or other aid organizations
(New) Bulgarian Enlighteners and Ambassadors? The Reinvention of National Identity in Times of Crisis
Drawing on empirical data from 37 Bulgarian students and young professionals in the UK, this article explores the intersection of the discourses produced by the European crises and migrants' national identity. In Bulgaria, the crisis narrative is embedded in the arguably neverâending democratic transition, manifested in socioâeconomic instability and political volatility. Simultaneously, âBrexit Britainâ is enveloped in strong Eurosceptic sentiments, propelled by a combination of austerity measures and intensified Eastern European migratory flows. Both contexts subject Bulgarian migrants to stigmatizing representations. Looking at migrants' everyday practices, the data reveals that young Bulgarians draw on the related ideas of the ânewâ Enlightener and Ambassador to counterbalance negative discourses. Thus, the article explores the meanings and significance attributed to the Enlighteners and the Ambassadors, arguing that the participants engage in âsocial creativityâ and âindividual mobilityâ strategies that lead to reinvention of national identity
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