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A Longitudinal U.S. State-Level Analysis of Organic Food Production and Greenhouse Gas Emissions
The question of whether organic farming is environmentally beneficial is not only contentious but also not well understood. Organic farming, which has been centered on the idea that increased soil health and vitality would result in more nutritious food and pest resistant crops, can also represent a significant means to tackle climate change. My research addresses the following question: Controlling for other sources of greenhouse gas (GHG) emissions, how do GHG emissions vary across U.S. states and over time with the proportion of total farmland devoted to organic cropland? This research question leads to three testable hypotheses. The first hypothesis, denoted as the Neutrality Hypothesis, posits that there exists no statistically significant relationship between organic cropland acreage and GHG emissions. The second hypothesis, denoted as the Mitigating Effect Hypothesis, is that increased organic cropland acreage is associated with lower GHG emissions. The final hypothesis, denoted as the Polluting Hypothesis, is that more organic cropland acreage is associated with higher GHG emissions. Most previous research has relied on lifecycle analysis (LCA) and has yielded estimation results that varied across products, product groups, locations, methodology, data, and even across studies assessing the same products. On the other hand, a recent study using multiple regression analysis presented questionable evidence contending a negative environmental impact for organic farming.
My research deviates from LCA by making use of U.S. state-level data over the 1997-2010 period excluding the years 1998, 1999, and 2009, multiple regression analysis, and a model consistent with the Stochastic Impacts by Regression on Population, Affluence, and Technology approach. Overall, there is evidence supporting the Mitigating Effect Hypothesis. Indeed, after controlling for other sources of GHG emissions, a one percent growth in organic farming is estimated to lower GHG emissions by 0.06% across U.S. states. This suggests that at the current rate of growth in organic farming, GHG emissions could decrease by about 7.7% by 2030 and by 12.8% by 2050 relative to the current level of emissions. In addition, in an assessment of the interaction between organic farming and the transportation sector, I find that the effect of organic farming on CH4 and N2O emissions depends on a state’s transportation output share (% of total state GDP). More specifically, at the current levels of transportation output, growth in organic farming is expected to mitigate CH4 and N2O emissions across most U.S. states. This would suggest that the environmental harm that transportation output contributes to organic food production might be too negligible to outweigh the environmental benefits of organic farming practices. A cluster analysis confirms these findings by showing that the environmental impact of organic farming is below the country average for most U.S. states and across three measures of emissions.
Although organic farming practices are already environmentally beneficial, further improvements can be achieved through the adoption of regenerative organic farming and by replacing the current competitive environment between conventional and organic farming with a more symbiotic coexistence. The current study reveals GHG mitigation benefits associated with organic food production. Policymakers and scientists can build on these results to further develop the evidence base and policies needed to maximize the benefits of adopting organic farming practices
Multifragmentation of a very heavy nuclear system (I): Selection of single-source events
A sample of `single-source' events, compatible with the multifragmentation of
very heavy fused systems, are isolated among well-measured 155Gd+natU 36AMeV
reactions by examining the evolution of the kinematics of fragments with Z>=5
as a function of the dissipated energy and loss of memory of the entrance
channel. Single-source events are found to be the result of very central
collisions. Such central collisions may also lead to multiple fragment emission
due to the decay of excited projectile- and target-like nuclei and so-called
`neck' emission, and for this reason the isolation of single-source events is
very difficult. Event-selection criteria based on centrality of collisions, or
on the isotropy of the emitted fragments in each event, are found to be
inefficient to separate the two mechanisms, unless they take into account the
redistribution of fragments' kinetic energies into directions perpendicular to
the beam axis. The selected events are good candidates to look for bulk effects
in the multifragmentation process.Comment: 39 pages including 15 figures; submitted to Nucl. Phys.
Multifragmentation of a very heavy nuclear system (II): bulk properties and spinodal decomposition
The properties of fragments and light charged particles emitted in
multifragmentation of single sources formed in central 36AMeV Gd+U collisions
are reviewed. Most of the products are isotropically distributed in the
reaction c.m. Fragment kinetic energies reveal the onset of radial collective
energy. A bulk effect is experimentally evidenced from the similarity of the
charge distribution with that from the lighter 32AMeV Xe+Sn system. Spinodal
decomposition of finite nuclear matter exhibits the same property in simulated
central collisions for the two systems, and appears therefore as a possible
mechanism at the origin of multifragmentation in this incident energy domain.Comment: 28 pages including 14 figures; submitted to Nucl. Phys.
Schedule-dependent activity of 5-fluorouracil and irinotecan combination in the treatment of human colorectal cancer: in vitro evidence and a phase I dose-escalating clinical trial
Several schedules of 5-fluorouracil (FU) and irinotecan (IRI) have been shown to improve overall survival in advanced colorectal cancer (CRC). Preclinical evidence suggests that the sequential administration of IRI and FU produces synergistic activity, although their clinical use has not been fully optimised. We investigated the interaction between short-term exposure to SN-38, the active metabolite of IRI, and prolonged exposure to FU in human CRC HT-29 cells and observed that the synergism of action between the two agents can be increased by extending the time of cell exposure to FU and reducing the interval between administration of the two agents. Based on these findings, we performed a phase I trial in 25 advanced CRC patients using a modified IRI/FU regimen as first-line therapy and evaluated three dose levels of IRI (150–300 mg/m2) and two of continuous infusion of FU (800–1000 mg/m2) in a 3-weekly schedule. The most severe grade III–IV toxicities were neutropoenia in four cycles and diarrhoea in three. One patient achieved complete response (4%), 12 a partial response (48%), the overall response rate was 52% (±20, 95% CI); seven of 25 patients had stable disease (28%), the overall disease control was 80% (±16, 95% CI). This modified IRI/FU schedule is feasible and exhibits potentially interesting clinical activity
Emission time scale of light particles in the system Xe+Sn at 50 AMeV. A probe for dynamical emission ?
Proton and deuteron correlation functions have been investigated with both
impact parameter and emission source selections. The correlations of the system
(129Xe + natSn) at 50 AMeV have been measured with the 4 pi INDRA which
provides a complete kinematical description of each event. The emission time
scale analyzed with a quantum model reveals the time sequence of the light
particles emitted by the projectile-like fragment. The short and constant
emission time of the proton, independent of the impact parameter, can be
attributed to a preequilibrium process.Comment: 20 pages, with 11 included figures; Accepted by European Physics
Journal
Climate-smart agriculture practices for mitigating greenhouse gas emissions
Agricultural lands make up approximately 37% of the global land surface, and agriculture is a significant source of greenhouse gas (GHG) emissions, including carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Those GHGs are responsible for the majority of the anthropogenic globalwarming effect.Agricultural GHG emissions are associated with agricultural soil management (e.g. tillage), use of both synthetic and organic fertilisers, livestock management, burning of fossil fuel for agricultural operations, and burning of agricultural residues and land use change. When natural ecosystems such as grasslands are converted to agricultural production, 20-40% of the soil organic carbon (SOC) is lost over time, following cultivation.We thus need to develop management practices that can maintain or even increase SOC storage in and reduce GHG emissions from agricultural ecosystems. We need to design systematic approaches and agricultural strategies that can ensure sustainable food production under predicted climate change scenarios, approaches that are being called climate-smart agriculture (CSA). Climate-smart agricultural management practices, including conservation tillage, use of cover crops and biochar application to agricultural fields, and strategic application of synthetic and organic fertilisers have been considered a way to reduce GHG emission from agriculture. Agricultural management practices can be improved to decreasing disturbance to the soil by decreasing the frequency and extent of cultivation as a way to minimise soil C loss and/or to increase soil C storage. Fertiliser nitrogen (N) use efficiency can be improved to reduce fertilizer N application and N loss. Management measures can also be taken to minimise agricultural biomass burning. This chapter reviews the current literature on CSA practices that are available to reduce GHG emissions and increase soil C sequestration and develops a guideline on best management practices to reduce GHG emissions, increase C sequestration, and enhance crop productivity in agricultural production systems
CUBES: a UV spectrograph for the future
In spite of the advent of extremely large telescopes in the UV/optical/NIR range, the current generation of 8-10m facilities is likely to remain competitive at ground-UV wavelengths for the foreseeable future. The Cassegrain U-Band Efficient Spectrograph (CUBES) has been designed to provide high-efficiency (>40%) observations in the near UV (305-400 nm requirement, 300-420 nm goal) at a spectral resolving power of R>20,000, although a lower-resolution, sky-limited mode of R ~ 7,000 is also planned. CUBES will offer new possibilities in many fields of astrophysics, providing access to key lines of stellar spectra: a tremendous diversity of iron-peak and heavy elements, lighter elements (in particular Beryllium) and light-element molecules (CO, CN, OH), as well as Balmer lines and the Balmer jump (particularly important for young stellar objects). The UV range is also critical in extragalactic studies: the circumgalactic medium of distant galaxies, the contribution of different types of sources to the cosmic UV background, the measurement of H2 and primordial Deuterium in a regime of relatively transparent intergalactic medium, and follow-up of explosive transients. The CUBES project completed a Phase A conceptual design in June 2021 and has now entered the Phase B dedicated to detailed design and construction. First science operations are planned for 2028. In this paper, we briefly describe the CUBES project development and goals, the main science cases, the instrument design and the project organization and management
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