Model for reflection and transmission matrices of nanowire end facets

Nanowires show a large potential for various electrooptical devices, such as light emitting diodes, solar cells and nanowire lasers. We present a direct method developed to calculate the modal reflection and transmission matrix at the end facets of a waveguide of arbitrary cross section, resulting in a generalized version of the Fresnel equations. The reflection can be conveniently computed using Fast Fourier Transforms. We demonstrate that the reflection is qualitatively described by two main parameters, the modal field confinement and the average Fresnel reflection of the plane waves constituting the waveguide mode.Comment: 11 pages,14 figure

Patients with ALS show highly correlated progression rates in left and right limb muscles.

ObjectiveAmyotrophic lateral sclerosis (ALS) progresses at different rates between patients, making clinical trial design difficult and dependent on large cohorts of patients. Currently, there are few data showing whether the left and right limbs progress at the same or different rates. This study addresses rates of decline in specific muscle groups of patients with ALS and assesses whether there is a relationship between left and right muscles in the same patient, regardless of overall progression.MethodsA large cohort of patients was used to assess decline in muscle strength in right and left limbs over time using 2 different methods: The Tufts Quantitative Neuromuscular Exam and Accurate Test of Limb Isometric Strength protocol. Then advanced linear regression statistical methods were applied to assess progression rates in each limb.ResultsThis report shows that linearized progression models can predict general slopes of decline with good accuracy. Critically, the data demonstrate that while overall decline is variable, there is a high degree of correlation between left and right muscle decline in ALS. This implies that irrespective of which muscle starts declining soonest or latest, their rates of decline following onset are more consistent.ConclusionsFirst, this study demonstrates a high degree of power when using unilateral treatment approaches to detect a slowing in disease progression in smaller groups of patients, thus allowing for paired statistical tests. These findings will be useful in transplantation trials that use muscle decline to track disease progression in ALS. Second, these findings discuss methods, such as tactical selection of muscle groups, which can improve the power efficiency of all ALS clinical trials

Silvopasture principles and potential in Saskatchewan

Non-Peer ReviewedSilvopasture is a concept in which woody species are intentionally combined with forage crops and livestock in a production system that optimizes the productivity or the economic benefits of the trees and the animals in a sustainable way. A review is presented of silvopasture research relevant to Saskatchewan conditions. In particular, silvopasture principles, as they apply to the co-management of animals with planted or natural forest stands will be explored. Silvopasture practices that are more or less commonly found in Canada include: the use of livestock to control weeds in new plantations; the planting or management of trees and shrubs as livestock windbreaks or for shade; and livestock grazing in natural deciduous, conifer or mixed forests

The N=8 Supergravity Hamiltonian as a Quadratic Form

We conjecture that the light-cone Hamiltonian of N=8 Supergravity can be expressed as a quadratic form. We explain why this rewriting is unique to maximally supersymmetric theories. The N=8 quartic interaction vertex is constructed and used to verify that this conjecture holds to second order in the coupling constant

Working together: the roles of geographic proximity, homophilic organizational characteristics, and neighborhood context in civic stewardship collaboration networks in Philadelphia and New York City

This is the final version. Available from Resilience Alliance via the DOI in this record. We examine networks of collaboration among civic environmental stewardship organizations in Philadelphia and New York City to understand which factors shape collaborative ties between organizations. Environmental issues in cities are increasingly complicated and often involve many actors, including citizens, governments, and organizations. Organizations frequently collaborate to tackle collective action problems related to environmental management. Here, we study two such networks collected as part of the U.S. Forest Service’s Stewardship Mapping and Assessment (STEW-MAP) project that monitors and maps the organizational characteristics of local environmental groups. We apply Exponential Random Graph models to demonstrate that network motifs, spatial proximity, organizational attributes, neighborhood context, and main issue focus all play different roles in explaining organizational collaboration among civic groups, but in very different ways across the two cities. Our findings reveal that civic networks are more correlated with homophily by social issues in Philadelphia, whereas civic networks in New York City are often correlated with geography proximity and homophily in land use. The comparative framework, still relatively rare in studies of environmental stewardship organizations, shows that different types of homophily, corresponding to different theoretical motivations, are at work in these cities. We conclude with some speculation as to the causes of these differences and their implications.US Forest Agenc

Trace Properties from Separation Logic Specifications

We propose a formal approach for relating abstract separation logic library specifications with the trace properties they enforce on interactions between a client and a library. Separation logic with abstract predicates enforces a resource discipline that constrains when and how calls may be made between a client and a library. Intuitively, this can enforce a protocol on the interaction trace. This intuition is broadly used in the separation logic community but has not previously been formalised. We provide just such a formalisation. Our approach is based on using wrappers which instrument library code to induce execution traces for the properties under examination. By considering a separation logic extended with trace resources, we prove that when a library satisfies its separation logic specification then its wrapped version satisfies the same specification and, moreover, maintains the trace properties as an invariant. Consequently, any client and library implementation that are correct with respect to the separation logic specification will satisfy the trace properties

On the effect of current pulses on the material behavior during electromagnetic metal forming

Electromagnetic sheet metal forming (EMF) is an example of a high-speed forming process driven by the dynamics of a coupled electromagnetic-mechanical system. Basic physical processes involved in EMF, such as e.g. inelastic and hardening behavior or inertia, have been considered in previous works [1, 2]. The purpose of the current work is the investigation of temperature development during EMF and a possible reduction in the yield stress due to electric currents. While thermoelastic and viscoplastic effects are well-understood in this context [3], the possible influence of electric currents on dislocation motion, generally referred to as the electro-plastic effect [4, 5], is still an unresolved issue. In agreement with previous works [e.g., 6], it is concluded here that such an effect is at most of second-order and can most likely be safely neglected in the modeling and simulation of industrial EMF