Eta invariants for flat manifolds

Using H. Donnelly result from the article "Eta Invariants for G-Spaces" we calculate the eta invariants of the signature operator for almost all 7-dimensional flat manifolds with cyclic holonomy group. In all cases this eta invariants are an integer numbers. The article was motivated by D. D. Long and A. Reid article "On the geometric boundaries of hyperbolic 4-manifolds, Geom. Topology 4, 2000, 171-178Comment: 18 pages, a new version with referees comment

Optical lock-in camera for gravitational wave detectors

Knowledge of the intensity and phase profiles of spectral components in a coherent optical field is critical for a wide range of high-precision optical applications. One of these is interferometric gravitational wave detectors, which rely on the optical beats between these fields for precise control of the experiment. Here we describe an optical lock-in camera and show that it can be used to record optical beats at MHz or greater frequencies with higher spatial and temporal resolution than previously possible. This improvement is achieved using a Pockels cell as a fast optical switch to transform each pixel on a sCMOS array into an optical lock-in amplifier. We demonstrate that the optical lock-in camera can record fields with 2 Mpx resolution at 10 Hz with a sensitivity of -62 dBc when averaged over 2s.Huy Tuong Cao, Daniel D. Brown, Peter J. Veitch, and David J. Ottawa

Irrigated small-grain residue management effects on soil chemical and physical properties and nutrient cycling

The effects of straw removal from irrigated wheat and barley fields cropped to wheat and barley on soil properties and nutrient cycling is a concern due to its potential impact on the sustainability of agricultural production. Increasing demand of straw for animal bedding and the potential development of cellulosic ethanol production will likely increase the demand in the future. Previous reviews addressing changes in soil properties when crop residues are removed focused primarily on rain-fed systems. This paper reviews published research assessing the effects of wheat and barley straw removal on soil organic carbon (SOC), and analyzes changes in nutrient cycling within irrigated wheat and barley production systems. The effects of straw removal on bulk density (BD), saturated hydraulic conductivity, and other properties are reported from selected studies. Six studies compared SOC changes with time in irrigated systems in which wheat straw was removed or retained. These studies indicated that SOC either increased with time or remained constant when residues were removed. It is possible that belowground biomass is supplying C to soils at a rate sufficient to maintain or in some cases, slowly increase SOC with time. A separate research review calculated the minimum aboveground residue required to maintain SOC levels (MCS) from nine wheat system studies. Calculations of the MCS values were from rain-fed systems and are some of the best information available presently for use in evaluating residue removal effects in irrigated systems. However, long-term studies are needed to obtain reliable data for diverse irrigated systems. Nutrients removed from the soil/plant system with straw can be worth $7 to$20 per Mg of straw removed. Producers will need to determine the cost of the nutrient removal from their systems to determine the value of the straw

Impact of removing straw from wheat and barley fields: A literature review

The sustainability of straw removal from wheat and barley fields from the standpoint of its effects on soil properties and nutrient cycling is a concern. A recent literature review reveals that there is no negative effect of small grain straw removal on soil organic carbon (SOC) content with irrigated conditions. With rainfed conditions, the results could be more variable and depend on site productivity. Large amounts of nutrients are removed when straw is removed, accelerating the rate of nutrient depletion and cost of replacing these nutrients

Small Grain Residue Management Effects on Soil Organic Carbon: A Literature Review

Impact of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) straw removal from fields on soil organic C (SOC) is a concern. Increased animal populations and potential development of cellulosic ethanol production could increase the removal of straw from fields. This paper focuses on the effects of wheat and barley straw removal on SOC in irrigated production systems, and related the results to estimates of the minimum straw C inputs required to maintain SOC (MSC) from rain-fed systems. Six studies compared SOC changes with time in irrigated systems in which wheat straw was removed or retained. These studies indicated that SOC did not decline when residues were removed. Apparently belowground biomass is supplying C to irrigated soils at a rate sufficient to maintain SOC with time. However, under rain-fed systems, returning residue to the soil was required to maintain SOC. Estimates of MSC were obtained from nine rain-fed wheat system studies. Averaged across all rain-fed MSC values, 4.14 Mg more straw per ha was required to maintain SOC in rain-fed than in irrigated systems. Presently, the rain-fed based MSC values are the best information available to evaluating residue removal effects but caution should be used in applying these in irrigated systems. The results from this limited number of irrigated studies suggest that rain-fed estimates of MSC will overestimate the MSC in irrigated systems and underestimate the available irrigated straw resources. There is need to evaluate the effect of residue removal on SOC for diverse irrigated systems

Irrigation small grain residue management effects on soil properties

The effects of straw removal from fields under irrigated wheat and barley on soil properties has become a potential concern in Idaho. The demand of straw for animal bedding and feed, and the potential development of cellulosic ethanol production will likely increase in the future. This paper reviews published research assessing the effects of wheat and barley straw removal on soil organic carbon (SOC), and analyzes changes in nutrient cycling within wheat and barley production systems. Six studies compared SOC changes with time in irrigated systems in which wheat was removed or retained. These studies indicate that reductions in SOC due to removal may not be a concern. Soil OC either increased with time or remained constant when residues were removed. It is possible that belowground biomass is supplying C to soils at a rate sufficient to maintain or in some cases, slowly increase SOC with time. A separate research review calculated the minimum aboveground residue required to maintain SOC levels from nine wheat system studies. Eight of the studies were dryland production systems. The grain yields required to produce sufficient above ground biomass to maintain SOC levels ranged from 9 to 122 bu acre-1 for wheat and 14 to 185 bu acre-1 for barley. Wheat straw contains approximately 15, 3.4, and 33 lbs nitrogen (N), phosphorus (P2O5), and potassium (K2O) ton-1, respectively. Barley straw contains approximately 12, 3.9, and 38 lbs N, P2O5, and K2O ton-1, respectively. The calculated total economic value of the N, P2O5, and K2O in one ton of wheat and barley straw is $17.91 and$18.18, respectively, based on average nutrient costs in the Pacific Northwest in 2007. Rotations including wheat and barley in the irrigated agriculture of Idaho and many other states in the Pacific Northwest are much different than what was reported in the reported studies. There is very little reported data that can be directly related the irrigated rotations in Idaho that include wheat or barley. To fully understand the impacts of crop residue removal from soils in Idaho, research projects need to be conducted on crop rotations that include wheat and barley under irrigated conditions in Idaho. Otherwise the best data available for dissemination is from research conducted in different environments and systems

Providing the Context for Intentional Learning

This article is written in response to Sharon Derry's article “Remediating Academic Difficulties Through Strategy Training: The Acquisition of Useful Knowledge.” The features of effective strategy instruction, to which Derry refers, are illustrated by examining the nature of the decisions the teacher confronts; specifically, determining the purposes of instruction, the context in which instruction occurs, and the roles of the teacher and students in instruction.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69150/2/10.1177_074193259001100608.pd