The Impact of Contact Geometry on Sea Ice Stress and Fracture at the Scale of Ice Floes

Observations of stress and strain at the scale of ice floes are necessary to fill a gap in our understanding of sea ice mechanical behavior. Current climate and ice dynamics models represent ice mechanical properties using stress-strain relationships largely determined at laboratory-scale (\u3c1m) or from regional-scale (10+km) deformation observations. The former scale does not include all mechanisms of deformation operating in the ice pack; the latter aggregates multiple modes of deformation into non-physical fluid analogies. The Sea Ice Dynamics Experiment (SIDEx) was run in Feb-Mar 2021 to fill this gap, observing stress and strain at the scale of sea ice failure processes. Here we present stress sensor observations. Stress gages (N=31) were deployed over a 4.5km2 area in the southern Beaufort Sea to observe in-situ stress. These data were analyzed in the context of deformation observations from satellite imagery and local laser and radar interferometers to explain the drivers of sea ice stress variations before and after fracture. Three case studies between 14 March and 24 March, during which fractures propagated through the stress observing array, are presented here. We find that the contact geometry between floes, along with the regional motion that is driving the floes to interact, is consistent with the observed stress state, fracture, and orientation of stress post-fracture at local scale. When the floe is contiguous and fractures are far away, stress magnitude and orientation is similar across the entire domain and changes are highly correlated. As the floe fractures, spatial variability in stress increases and high stresses are found along the floe contacts. Peak stresses occur on or near contacting asperities, reaching up to 600 kPa, and along paths connecting contact points. The interrelation between stress state and geometry suggests that high fidelity models, initialized with realistic floe geometry, may have deterministic predictive capability for further ice fracture

A Policy Analysis of the Federal Growth Model Pilot Program\u27s Measures of School Performance: The Florida Case

As test-based educational accountability has moved to the forefront of national and state education policy, so has the desire for better measures of school performance. No Child Left Behind\u27s (NCLB) status and safe harbor measures have been criticized for being unfair and unreliable, respectively. In response to such criticism, in 2005 the federal government announced the Growth Model Pilot Program, which permits states to use projection models (a type of growth model) in their accountability systems. This article uses historical longitudinal data from a large school district to empirically show the inaccuracy of one state\u27s projection model, to demonstrate how projection models are very similar to NCLB\u27s original status measure, and to contrast projection models with value-added models. As policy makers debate the reauthorization of NCLB, this research can provide guidance on ways to improve the current measurement of school performance

INFLUENCE OF LAND TENURE ARRANGEMENTS ON GRAZING MANAGEMENT INCENTIVES

Land Economics/Use, Livestock Production/Industries,

FACTORS INFLUENCING OPTIMAL STOCKING RATES FROM A TENANT PERSPECTIVE

The terms of grazing lease contracts potentially influence the tenants incentive to preserve the vegetation resource. Annual stocking rate decisions dictate the degree of overgrazing, which can be cumulative over long periods of time. The objective of this study is to identify the impact the tenants planning horizon and cost structure specified in the lease contract has on his/her profit-maximizing stocking rate. A multi-period nonlinear programming model was developed to identify economically optimal stocking rates each year over a 24-year period. The model was solved under 1-, 4-, 8-, and 12-year leases on a per acre and per head basis. The relative importance of each lease alternative and input variable on the tenants optimal stocking rate was ranked based on standardized ordinary least squares coefficient estimates between input values and optimal stocking rates. Planning horizon and cost structure had a minor impact on optimal stocking rates relative to non-lease factors such as livestock prices and production costs. Holding other factors constant, per acre leases generated a 2% higher average stocking rate than per head leases. Optimal stocking rates were inversely related to the length of the lease. Twelve-year lease agreements generated 18 and 13% lower optimal stocking rater than the 1-year per acre and per head lease agreements, respectively. The optimal stocking rate difference between an 8-year and a 12-year lease was negligible, suggesting the 8-year lease would provide a similar incentive to protect vegetation as a lease with a longer planning horizon.Environmental Economics and Policy, Land Economics/Use,

Transfer Printing of Photonic Nanostructures to Silicon Integrated Circuits

Optical systems require the integration of technologies fabricated on different materials. We use a transfer printing technique to integrate pre-processed III-V, polymer and silicon membrane devices onto passive optical circuits with nano-metric positional accuracy

PROFITABILITY OF ESTABLISHING BASIN WILDRYE FOR WINTER GRAZING

This study examined the economic viability of establishing basin wildrye for winter grazing. Mixed integer-programming models were developed that minimized cow feed costs. Estimated basin wildrye establishment costs were $154 per acre. Break-even basin wildrye yields were approximately 2.6 and 2.3 AUMs/acre for March and May calving scenarios, respectively.Livestock Production/Industries,

OPTIMAL FEED COST STRATEGIES ASSOCIATED WITH EARLY AND LATE CALVING SEASONS

Integer programming models were used to examine optimal monthly feeding strategies and costs for March and May calving alternatives. Body condition scores were allowed to fluctuate throughout the year except for calving and breeding periods. The May calving strategy decreased annual feeding costs by $20 per cow.Livestock Production/Industries, Research Methods/ Statistical Methods,

AMPHIBIAN AND REPTILE COLONIZATION OF RECLAIMED COAL SPOIL GRASSLANDS

While habitat loss is a major driver of amphibian and reptile declines globally, a subset of post-industrial landscapes, reclaimed and restored, are creating habitat for these animals. In a previous work, we showed that amphibians and reptiles use reclaimed and restored grasslands. In the present work we quantify captures at drift-fence/pitfall trap arrays over two consecutive years and show that several species of amphibians are not only successfully reproducing but that juveniles are being recruited into the population. In particular, 15,844 amphibians and 334 reptiles representing 25 species (14 amphibians, 11 reptiles) were captured at drift fences in 2009 and 2010. Nine additional reptile species were found opportunistically while conducting other research activities at the study site. Out of a total of 8,064 metamorphosing juveniles we detected 126 malformations, a 1.6% rate. The major malformation types were limbs missing (amelia) or foreshortened (ectromely), eye discolorations, and digits foreshortened (ectrodactyly) or small (brachydactyly). Our data show that reclaimed, restored, and properly managed landscapes can support reproducing populations of amphibians and reptiles with low malformation rates, including species in decline across other portions of their range