FARMERS' DECISION PROCESSES AND ADOPTION OF CONSERVATION TILLAGE

In a transect survey of crop residue levels in 1995 and 1996, two Minnesota counties had very different percentages of cropland with desired residue cover even though the soil types were similar. To gain a better understanding of the reasons behind this difference, the farmers in these two counties were surveyed about their use or lack of use of conservation tillage practices. A statistical logit analysis of survey responses showed farmers are more apt to adopt conservation tillage if they are larger; are more concerned about erosion on their land; have made a recent major investment in the farm; use other producers for tillage information; have the management skill for conservation tillage; and believe conservation tillage will fit with their production goals and the physical setting of their farm. Two counterintuitive findings are the negative effects of the ease of finding information and the degree of control of the adoption decision. The costs and labor requirements of conservation tillage were important but not as statistically significant as those factors just listed. Some variables, that are often listed as potentially important factors, were not found to be important in this survey. These included the long-term viability of the farm; the age, education, and experience of the farmer; the debt level of the farm; whether a family member wanted to continue farming; the proportion of land rented; the use of other sources for tillage information; the complexity of conservation tillage practices; the producer's planning horizon; the risk of negative returns; the availability of support for conservation tillage systems; and the quality of conservation tillage information.Crop Production/Industries,

ENVIRO-ECONOMIC ANALYSIS OF PHOSPHORUS NONPOINT POLLUTION

The state of Minnesota seeks to reduce phosphorus loading to the Minnesota River by 40% from current levels. The state agency charged with achieving this reduction has indicated each watershed should reduce its current phosphorus loading by 40%. We hypothesized that policies targeting specific practices or regions would have a smaller negative impact on farm income than policies requiring every nonpoint polluter to reduce its contribution by 40%. Using a stylized version of one major watershed in the river basin as an example, we analyzed the cost-effectiveness of various nonpoint pollution reduction policies. We simulated current and alternative farming systems (designed to reduce phosphorus loading by changing tillage or fertilizer practices) in distinct regions within the watershed using a biophysical process model. For each system, estimates of phosphorus loading from biophysical simulation were combined with production cost and return estimates to create an enviro-economic model of the watershed. Additionally, risk premiums were estimated and included with cost estimates for each alternative system. We used a positive math-programming (PMP) version of the enviro-economic model to analyze nonpoint pollution reduction policies (pollution standard, phosphorus effluent tax, conventional tillage tax, and phosphorus fertilizer tax). When regions and practices within the watershed could be targeted for achieving the pollution reduction standard, 13,500 fewer hectares (6% reduction from the baseline cropland level) were farmed. When the same standard was uniformly applied to all regions (not targeted), cropland decline by 40,500 hectares (20%). Under either scenario, cropland was removed from production, implying some producers may exit farming. Cropland reductions resulted in farmers losing $2.8 million (5$11.4 million (21%). This finding illustrates how difficulty it is to reduce nonpoint pollution if one does not focus on specific regions. An effluent tax of $74 per kilogram of phosphorus reaching the river was needed to reduce phosphorus loading by 40$14 million (25% reduction from the baseline income level), $11 million of which were revenues from the effluent tax. Neither the conventional tillage tax nor the phosphorus fertilizer tax achieved a 40% reduction in phosphorus loading. This finding illustrates the difficulty of reducing nonpoint pollution by focusing only on one practice. Under a pollution-reduction standard, our results indicated it is more cost effective to reduce nonpoint pollution by targeting particular regions or practices in a watershed compared to not targeting. Specifically, producers farming on cropland susceptible to erosion in close proximity to water who switch from conventional tillage to conservation tillage and reduce phosphorus fertilization levels to those recommended by the state extension service will appreciably reduce phosphorus nonpoint pollution loading potential. Efforts to target those producers could minimize potential losses in farm income in the watersheds and the river basin.Environmental Economics and Policy,

Nonequilibrium Approach to Bloch-Peierls-Berry Dynamics

We examine the Bloch-Peierls-Berry dynamics under a classical nonequilibrium dynamical formulation. In this formulation all coordinates in phase space formed by the position and crystal momentum space are treated on equal footing. Explicitly demonstrations of the no (naive) Liouville theorem and of the validity of Darboux theorem are given. The explicit equilibrium distribution function is obtained. The similarities and differences to previous approaches are discussed. Our results confirm the richness of the Bloch-Peierls-Berry dynamics

Different Ways of Reading, or Just Making the Right Noises?

What does reading look like? Can learning to read be reduced to the acquisition of a set of isolable skills, or proficiency in reading be equated with the independence of the solitary, silent reader of prose fiction? These conceptions of reading and reading development, which figure strongly in educational policy, may appear to be simple common sense. But both ethnographic data and evidence from literary texts suggest that such paradigms offer, at most, a partial and ahistorical picture of reading. An important dimension, neglected in the dominant paradigms, is the irreducibly social quality of reading practices

Large Scale Flame Spread Environmental Characterization Testing

Under the Advanced Exploration Systems (AES) Spacecraft Fire Safety Demonstration Project (SFSDP), as a risk mitigation activity in support of the development of a large-scale fire demonstration experiment in microgravity, flame-spread tests were conducted in normal gravity on thin, cellulose-based fuels in a sealed chamber. The primary objective of the tests was to measure pressure rise in a chamber as sample material, burning direction (upward/downward), total heat release, heat release rate, and heat loss mechanisms were varied between tests. A Design of Experiments (DOE) method was imposed to produce an array of tests from a fixed set of constraints and a coupled response model was developed. Supplementary tests were run without experimental design to additionally vary select parameters such as initial chamber pressure. The starting chamber pressure for each test was set below atmospheric to prevent chamber overpressure. Bottom ignition, or upward propagating burns, produced rapid acceleratory turbulent flame spread. Pressure rise in the chamber increases as the amount of fuel burned increases mainly because of the larger amount of heat generation and, to a much smaller extent, due to the increase in gaseous number of moles. Top ignition, or downward propagating burns, produced a steady flame spread with a very small flat flame across the burning edge. Steady-state pressure is achieved during downward flame spread as the pressure rises and plateaus. This indicates that the heat generation by the flame matches the heat loss to surroundings during the longer, slower downward burns. One heat loss mechanism included mounting a heat exchanger directly above the burning sample in the path of the plume to act as a heat sink and more efficiently dissipate the heat due to the combustion event. This proved an effective means for chamber overpressure mitigation for those tests producing the most total heat release and thusly was determined to be a feasible mitigation strategy to incorporate into the microgravity experiment

Altered progesterone concentrations by hormonal manipulations before a fixed-time artificial insemination CO-Synch + CIDR program in suckled beef cows

We hypothesized that pregnancy outcomes may be improved by inducing luteal regression, ovulation, or both (i.e., altering progesterone status) before initiating a timed–artificial insemination (TAI) program in suckled beef cows. This hypothesis was tested in two experiments in which cows were treated with either PGF[subscript 2α] (PG) or PG + GnRH before initiating a TAI program to increase the proportion of cows starting the program in a theoretical marginal (<1 ng/mL; experiment 1) or elevated (≥1 ng/mL; experiment 2) progesterone environment, respectively. The control was a standard CO-Synch + controlled internal drug release (CIDR) program employed in suckled beef cows (100 μg GnRH intramuscularly [IM] [GnRH-1] and insertion of a progesterone-impregnated intravaginal CIDR insert on study Day −10, 25 mg PG and CIDR insert removal on study Day −3, and 100 μg GnRH IM [GnRH-2] and TAI on study Day 0). In both experiments, blood was collected before each injection for later progesterone analyses. In experiment 1, cows at nine locations (n = 1537) were assigned to either: (1) control or (2) PrePG (same as control with a PG injection on study Day −13). The PrePG cows had larger (P < 0.05) follicles on study Day −10 and more (P < 0.05) ovulated after GnRH-1 compared with control cows (60.6% vs. 36.5%), but pregnancy per TAI was not altered (55.5% vs. 52.2%, respectively). In experiment 2, cows (n = 803) at four locations were assigned to: (1) control or (2) PrePGG (same as control with PG injection on study Day −20 and GnRH injection on study Day −17). Although pregnancy per TAI did not differ between control and PrePGG cows (44.0% vs. 44.4%, respectively), cows with body condition score greater than 5.0 or 77 or more days postpartum at TAI were more (P < 0.05) likely to become pregnant than thinner cows or those with fewer days postpartum. Presynchronized cows in both experiments were more (P < 0.05) likely than controls to have luteolysis after initial PG injections and reduced (P < 0.05) serum progesterone; moreover, treatments altered the proportion of cows and pregnancy per TAI of cows in various progesterone categories before the onset of the TAI protocol. In combined data from both experiments, cows classified as anestrous before the study but with elevated progesterone on Day −10 had increased (P < 0.05) pregnancy outcomes compared with anestrous cows with low progesterone concentrations. Progesterone concentration had no effect on pregnancy outcome of cycling cows. In summary, luteal regression and ovulation were enhanced and progesterone concentrations were altered by presynchronization treatments before the 7-day CO-Synch + CIDR program, but pregnancy per TAI was not improved

Crystal Structure of a Nonsymbiotic Plant Hemoglobin

Background: Nonsymbiotic hemoglobins (nsHbs) form a new class of plant proteins that is distinct genetically and structurally from leghemoglobins. They are found ubiquitously in plants and are expressed in low concentrations in a variety of tissues including roots and leaves. Their function involves a biochemical response to growth under limited O2 conditions. Results: The first X-ray crystal structure of a member of this class of proteins, riceHb1, has been determined to 2.4 Å resolution using a combination of phasing techniques. The active site of ferric riceHb1 differs significantly from those of traditional hemoglobins and myoglobins. The proximal and distal histidine sidechains coordinate directly to the heme iron, forming a hemichrome with spectral properties similar to those of cytochrome b5. The crystal structure also shows that riceHb1 is a dimer with a novel interface formed by close contacts between the G helix and the region between the B and C helices of the partner subunit. Conclusions: The bis-histidyl heme coordination found in riceHb1 is unusual for a protein that binds O2 reversibly. However, the distal His73 is rapidly displaced by ferrous ligands, and the overall O2 affinity is ultra-high (KD ≈ 1 nM). Our crystallographic model suggests that ligand binding occurs by an upward and outward movement of the E helix, concomitant dissociation of the distal histidine, possible repacking of the CD corner and folding of the D helix. Although the functional relevance of quaternary structure in nsHbs is unclear, the role of two conserved residues in stabilizing the dimer interface has been identified

Psychedelics Promote Structural and Functional Neural Plasticity.

Atrophy of neurons in the prefrontal cortex (PFC) plays a key role in the pathophysiology of depression and related disorders. The ability to promote both&nbsp;structural and functional plasticity in the PFC has been hypothesized to underlie the fast-acting antidepressant properties of the dissociative anesthetic ketamine. Here, we report that, like ketamine, serotonergic psychedelics are capable of robustly increasing neuritogenesis and/or spinogenesis both in&nbsp;vitro and in&nbsp;vivo. These changes in neuronal structure are accompanied by increased synapse number and function, as measured by fluorescence microscopy and electrophysiology. The structural changes induced by psychedelics appear to result from stimulation of the TrkB, mTOR, and 5-HT2A signaling pathways and could possibly explain the clinical effectiveness of these compounds. Our results underscore the therapeutic potential of psychedelics and, importantly, identify several lead scaffolds for medicinal chemistry efforts focused on developing plasticity-promoting compounds as safe, effective, and fast-acting treatments for depression and related disorders