Distributional Impact of U.S. Farm Commodity Programs: Accounting for Alternative Farm Household Typologies

Agricultural households adjust to policy changes through market mechanisms by altering: their production mix, labor input, and on- and off-farm investments. Because of the significant heterogeneity among farms in the US agricultural sector, various types of farm households respond to the same policy change in significantly different ways. The parameters used to classify farm households into different typologies may also play a significant role in the interpretation of observed effects of policy changes. This paper, using a highly disaggregated U.S. Computable General Equilibrium (CGE) model, analyzes the distributional impacts of policy changes involving price-contingent government payments on alternative U.S. farm household typologies. We find that farm households do vary their responses to an elimination of price-contingent support based on location, production specialty, and farm categorization.Agricultural and Food Policy,

Displacement Damage and Self-Healing in High-Entropy Alloys: a TEM with in situ ion irradiation study

Recent developments in the field of materials for future nuclear fusion reactors have led to the design of innovative metallic alloys that can sustain their mechanical and structural properties under a wide variety of extreme conditions, such as fast neutrons (E <= 14 MeV) and alpha particle bombardment (4He with E up to ~ 3.5 MeV). High-Entropy Alloys (HEAs) are promising candidates for new concepts of nuclear reactors as they have mechanical properties and thermodynamic stability that is believed to be superior to conventional metallic alloys, although their radiation resistance is still a subject of intense research. The efforts to understand the behavior of HEAs under particle irradiation indicated a possible “self-healing” effect of radiation induced defects. In this report, a preliminary study using Transmission Electron Microscopy (TEM) with in situ ion irradiation was performed to investigate the formation and evolution of displacement damage in the microstructure of a FeCrMnNi HEA

Accessible and sustainable Cu(0)-mediated radical polymerisation for the functionalisation of surfaces

Polymer brushes have great potential for use in functionalising surfaces due to their chemical and mechanical robustness, and wide variety of useful properties including antibacterial and antifouling behaviour. One such grafted polymer of interest is poly[2-(methacryloyloxy)ethyl]trimethylammonium chloride (PMETAC), shown to have excellent antibacterial behaviour due to the presence of quaternary ammonium chloride groups (QACs). Previous studies have shown that increasing the density of QACs increases the efficacy of these surfaces, therefore the production of thick PMETAC brushes is highly desirable. Cu(0)-mediated radical polymerisation (CuRP) offers a simple route to the production of these surfaces. A movement towards more sustainable chemistry has led to research into polymerisations in environmentally benign solvent, with focus placed on recycled and easily accessible catalysts. In this study, the growth of PMETAC brushes up to 300 nm dry thickness (∼ 425 nm water-swollen thickness) is demonstrated, thicker than any previous report we have found for this polymer brush. Furthermore, tap water is used as a cheap and readily available solvent, with a catalyst derived from copper wire. The use of copper wire, compared to the commonly used CuBr2 catalyst, leads to thicker coatings which also display a lower swelling ratio, implying an increased grafting density. The protocol can be continuously cycled over a 7-day period without changing the monomer solution or catalyst, with numerous wafers being functionalised over the time period with no significant reduction in grafted amount. In addition, the polymerisation can be carried out in ambient (non-inert) conditions with no degassing steps, again without with significant detriment to grafting

When Do People Trust Their Social Groups?

Trust facilitates cooperation and supports positive outcomes in social groups, including member satisfaction, information sharing, and task performance. Extensive prior research has examined individuals' general propensity to trust, as well as the factors that contribute to their trust in specific groups. Here, we build on past work to present a comprehensive framework for predicting trust in groups. By surveying 6,383 Facebook Groups users about their trust attitudes and examining aggregated behavioral and demographic data for these individuals, we show that (1) an individual's propensity to trust is associated with how they trust their groups, (2) smaller, closed, older, more exclusive, or more homogeneous groups are trusted more, and (3) a group's overall friendship-network structure and an individual's position within that structure can also predict trust. Last, we demonstrate how group trust predicts outcomes at both individual and group level such as the formation of new friendship ties.Comment: CHI 201

Preliminary assessment of the irradiation behaviour of the FeCrMnNi High-Entropy Alloy for nuclear applications

In the search for new nuclear materials with improved radiation tolerance and behavior, the high-entropy alloys (HEAs) have arisen as new candidates for structural components in nuclear reactors due to their suspected superior stability under irradiation. The metallurgical definition of HEAs is any alloy with multiple elements, five or more all in equiatomic compositions. The basic principle is the high mixing entropy of its solid solution lowers the Gibbs free energy giving a strong enhancement of the microstructural stability at low and high temperatures. The objective of this project is to assess the irradiation behaviour of the FeCrMnNi HEA system in order to investigate whether the high entropy effect is responsible for a microstructure with better radiation resistance compared to conventional alloys. In this work transmission electron microscopy (TEM) with in-situ ion irradiation has been used at the MIAMI-1 facility at the University of Huddersfield, UK: a 100 kV ion accelerator coupled with a JEOL JEM-2000FX TEM. This methodology allows the evolution of the HEA microstructure to be studied on the nanoscale during the ion irradiation

Preliminary assessment of the irradiation behaviour of the FeCrMnNi High-Entropy Alloy for nuclear applications

In the search for new nuclear materials with improved radiation tolerance and behavior, the high-entropy alloys (HEAs) have arisen as new candidates for structural components in nuclear reactors due to their suspected superior stability under irradiation. The metallurgical definition of HEAs is any alloy with multiple elements, five or more all in equiatomic compositions. The basic principle is the high mixing entropy of its solid solution lowers the Gibbs free energy giving a strong enhancement of the microstructural stability at low and high temperatures. The objective of this project is to assess the irradiation behaviour of the FeCrMnNi HEA system in order to investigate whether the high entropy effect is responsible for a microstructure with better radiation resistance compared to conventional alloys. In this work transmission electron microscopy (TEM) with in-situ ion irradiation has been used at the MIAMI-1 facility at the University of Huddersfield, UK: a 100 kV ion accelerator coupled with a JEOL JEM-2000FX TEM. This methodology allows the evolution of the HEA microstructure to be studied on the nanoscale during the ion irradiation

Switching the Interpenetration of Confined Asymmetric Polymer Brushes

The interpenetration of two polymer brushes on approaching flat surfaces has been investigated. When compacting polymer brushes with an asymmetric charge on each surface, one neutral and the other weakly charged, we find that the brush interpenetration becomes a parameter that can be controlled by the pH of the hydrating solution. The switching between high and low degrees of brush interpenetration was investigated with numerical self-consistent field theory (nSCF) and experimentally using a sample environment which combines neutron reflectometry with a surface force type apparatus. Initially, a pair of uncharged poly(ethylene oxide), PEO, brushes are examined, where one of the brushes is deuterated to distinguish it from a hydrogenous counterpart. We find in both nSCF and these experiments that there is no significant overlap between the brushes as both compact into polymer blocks with little hydration. However, when a weak polyelectrolyte poly(2-(dimethylamino)ethyl methacrylate), PDMAEMA, brush is confined against a deuterated neutral PEO brush and the pH of the hydrating solution is below the polycation’s pKa of 7.5, then the presence of charged groups on the PDMAEMA allows significant interpenetration to occur between the two polymer brushes on contact. This interpenetration remains once the polymer brushes dehydrate due to the confining pressure that is applied. Raising the pH to a value above the pKa, removes the charges from the polyelectrolyte brush resulting in little to no interpenetration between the two brushes. Therefore, by simply adjusting the pH of the hydrating solution the interpenetration state between polymer brush pairs can be switched when one brush is a weak polyelectrolyte. Since polymer brushes are widely investigated and used to reduce friction between solid surfaces, this effect may have significant implications in the design and operation of polymer brushes with controllable friction properties