Managing Resistant and Other Difficult to Control Weeds

Currently, weed control is practiced to a very intensive level of management in the Midwest. Most all acres of com and soybean production are treated with one or more herbicides, and often with multiple applications of herbicides. And yet weed problems remain that cause concern to the grower, in some instances because of potential losses due to competition and harvest losses, and in other instances because of grower, landlord, and neighbor expectations for near perfect control of all weedy species in growing crops. Some of these greater expectations come as a result of product guarantees and respray programs, which are sometimes implemented when no significant problem really exists

Deaf Community Leaders as Liaisons Between Mental Health and Deaf Cultures

Providing mental health services to deaf people is usually a formidable task. Given the movement to more ecological perspective on mental health issues in deaf people, it seems that two important features of successful mental health service delivery to deaf people would include in-depth understanding of experiential and cultural differences among people in the deaf community and development of a sturdy bridge between the mental health service provider community and the deaf community. This paper will describe the evolution of attempts in Washington State, from 1984 to 1987, to provide more adequate mental health services for deaf people. On the basis of these efforts, a deaf leader liaison model was developed and is being proposed here as a cost-effective means of meeting the mental health needs of a deaf community

Book Review

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Pigweeds of the Midwest- Distribution, Importance and Management

A number of pigweed species can be found throughout the Midwest, but we are most concerned about those species that are commonly found in cropping situations. The most common weedy pigweeds can be separated into three distinct groups according to their taxonomic characteristics and overall appearance. The first group includes some of the most common pigweeds in the Midwest: redroot pigweed (Amaranthus retroflexus), smooth pigweed (Amaranthus hybridus) and Powell amaranth (Amaranthus powellii)

Physical limitations of travel time based shallow water tomography

Travel-time-based tomography is a classical method for inverting sound-speed perturbations in an arbitrary environment. A linearization procedure enables relating travel-time perturbations to sound-speed perturbations through a kernel matrix. Thus travel-time-based tomography essentially relies on the inversion of the kernel matrix and is commonly called ‘linear inversion. In practice, its spatial resolution is limited by the number of resolved and independent arrivals, which is a basic linear algebra requirement for linear inversion performance. Physically, arrival independency is much more difficult to determine since it is closely related to the sound propagating channel characteristics. This paper presents a brief review of linear inversion and shows that, in deep water, the number of resolved arrivals is equal to the number of independent arrivals, while in shallow water the number of independent arrivals can be much smaller than the number of resolved arrivals. This implies that in shallow water there are physical limitations to the number of independent travel times. Furthermore, those limitations are explained through the analysis of an equivalent environment with a constant sound speed. The results of this paper are of central importance for the understanding of travel-time-based shallow water tomography

Research Notes: U.S. Regional Soybean Laboratory and University of Illinois, Urbana-Champaign

Chief\u27, a very tall Maturity Group IV variety, was used as a donor parent in backcrossing to \u27Clark\u27 to transfer Np (a gene for high phosphorus tolerance). In the field in 1963, I grew progenies from 40 selected Np F2 plants from Clark BC5 and was surprised to see 2 of the progenies uniformly very tall and 3 of them segregating approximately 1/4 tall plants. The Np gene appears to have no effect on field-grown plants in normal soils

Penetration depth of low-coherence enhanced backscattered light in sub-diffusion regime

The mechanisms of photon propagation in random media in the diffusive multiple scattering regime have been previously studied using diffusion approximation. However, similar understanding in the low-order (sub-diffusion) scattering regime is not complete due to difficulties in tracking photons that undergo very few scatterings events. Recent developments in low-coherence enhanced backscattering (LEBS) overcome these difficulties and enable probing photons that travel very short distances and undergo only a few scattering events. In LEBS, enhanced backscattering is observed under illumination with spatial coherence length L_sc less than the scattering mean free path l_s. In order to understand the mechanisms of photon propagation in LEBS in the subdiffusion regime, it is imperative to develop analytical and numerical models that describe the statistical properties of photon trajectories. Here we derive the probability distribution of penetration depth of LEBS photons and report Monte Carlo numerical simulations to support our analytical results. Our results demonstrate that, surprisingly, the transport of photons that undergo low-order scattering events has only weak dependence on the optical properties of the medium (l_s and anisotropy factor g) and strong dependence on the spatial coherence length of illumination, L_sc, relative to those in the diffusion regime. More importantly, these low order scattering photons typically penetrate less than l_s into the medium due to low spatial coherence length of illumination and their penetration depth is proportional to the one-third power of the coherence volume (i.e. [l_s \pi L_sc^2 ]^1/3).Comment: 32 pages(including 7 figures), modified version to appear in Phys. Rev.

Inpatient Psychiatric Services for Deaf and Hard-of-Hearing People: Where Are We Now?

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Characterization of a periodically driven chaotic dynamical system

We discuss how to characterize the behavior of a chaotic dynamical system depending on a parameter that varies periodically in time. In particular, we study the predictability time, the correlations and the mean responses, by defining a local--in--time version of these quantities. In systems where the time scale related to the time periodic variation of the parameter is much larger than the ``internal'' time scale, one has that the local quantities strongly depend on the phase of the cycle. In this case, the standard global quantities can give misleading information.Comment: 15 pages, Revtex 2.0, 8 figures, included. All files packed with uufile