Waller Creek Rapid Visual Litter Assessment Method and Baseline Results

This short report surveyed 10 different Waller Creek sites using a litter index field sheet that they designed. These scores were then assigned to each survey site.The Watershed Protection Department has developed a method to assess litter in creeks and provide a way to evaluate the success of litter management efforts in the lower Waller Creek watershed over time. A rapid visual litter assessment method was applied at ten sites on Waller Creek in downtown Austin, Texas, to describe the abundance and type of litter present at each site in addition to identification of possible sources of litter. Surveys were timed to provide an estimate of staff time necessary to conduct future litter surveys using this method. On average, to complete the survey at one site took between 6.7 and 7.5 minutes. Surveys concluded that there was a significant presence of litter in lower Waller Creek. Beverage containers were identified to be the most prevalent type of litter. Surveys identified a few point sources of litter. Additional data points at each site may be needed to more accurately describe baseline conditions in Waller Creek.Waller Creek Working Grou

Electro-optic network analyzer

The bandwidth of frequency domain measurement methods of electrical signals has usually been far greater than the bandwidth of time domain methods. The primary limits of the time domain approach have been the 20 to 30 GHz bandwidth limit for electronic waveform acquisition instrumentation, and the lack of usable electrical pulse generators for excitation of a test device. The bandwidth of frequency domain network analysis appears to have reached a plateau of between 100 to 200 GHz, while time domain measurement have improved markedly in both bandwidth and sensitivity with the introduction of the pulsed laser based electro-optic sampling approach. Network analysis or the measurement of device scattering parameters provides information necessary to the design of electronic network such as high frequency amplifiers, mixers, and phase shifter. The bandwidth of frequency domain network analysis is currently being exceeded by the next generations of high frequency transistors and devices. Thus the electro-optic approach is a natural means of extending network analysis into the range above 100 GHz by employing time domain methods. In this approach, a suitable electrical excitation pulse is generated and propagated along a transmission line toward a test device. In the picosecond domain, laser driven photoconductive switches provide a unique method of generating electrical transients. Several materials were studied for generating short electrical pulses using photoconductive switches. The various semiconductive materials tested for photoconductive switching, and the electro-optic measurement technique used to characterize the material performance are described

On Maltsev Digraphs

This is an Open Access article, first published by E-CJ on 25 February 2015.We study digraphs preserved by a Maltsev operation: Maltsev digraphs. We show that these digraphs retract either onto a directed path or to the disjoint union of directed cycles, showing in this way that the constraint satisfaction problem for Maltsev digraphs is in logspace, L. We then generalize results from Kazda (2011) to show that a Maltsev digraph is preserved not only by a majority operation, but by a class of other operations (e.g., minority, Pixley) and obtain a O(|VG|4)-time algorithm to recognize Maltsev digraphs. We also prove analogous results for digraphs preserved by conservative Maltsev operations which we use to establish that the list homomorphism problem for Maltsev digraphs is in L. We then give a polynomial time characterisation of Maltsev digraphs admitting a conservative 2-semilattice operation. Finally, we give a simple inductive construction of directed acyclic digraphs preserved by a Maltsev operation, and relate them with series parallel digraphs.Peer reviewedFinal Published versio

Performance Evaluation with Stochastic Discount Factors

We study the use of stochastic discount factor (SDF) models in evaluating the investment performance of portfolio managers. By constructing artificial mutual funds with known levels of investment ability, we evaluate a large set of SDF models. We find that the measures of performance are not highly sensitive to the SDF model, and that most of the models have a mild negative bias when performance is neutral. We use the models to evaluate a sample of U.S. equity mutual funds. Adjusting for the observed bias, we find that the average mutual fund has enough ability to cover its transactions costs. Extreme funds are more likely to have good rather than poor risk adjusted performance. Our analysis also reveals a number of implementation issues relevant to other applications of SDF models.

Supplemental Monitoring of Selected Water Bodies with Contact Recreation Impairments

This report contains data regarding E.coli, ammonia and nitrate levels in a variety of Waller Creek locations There are pictures of monitoring sites where the data was collectedNutrient and indicator bacteria data were collected at seven sites in five Austin creeks that are on the draft 2010 Clean Water Act section 303(d) list of impaired water bodies proposed by the TCEQ. The supplemental data was collected to verify the TCEQ assessment that the creeks are not supporting designated uses of primary contact recreation in the Texas Surface Water Quality Standards due to elevated bacteria levels (30 TAC 307.7(b)(1)(A)(i)). These streams may also be “of concern” under Clean Water Act section 305(b) due to nutrient enrichment. Flow monitoring indicated that Eanes Creek below the Barton Springs Edwards Aquifer recharge zone is ephemeral; therefore, the bacteria impairment for this site is not appropriate according to TCEQ assessment methodology. Bacteria levels are low enough at the Westlake-Davenport Tributary site to fully support primary contact recreation uses. Primary contact recreation is not supported at the Waller Creek, Taylor Slough South or Spicewood Tributary to Shoal Creek sites. Elevated nutrients at Waller Creek appear to be from and indeterminate source of sewage contamination and those at Westlake-Davenport are most likely from nearby residential fertilizer application.Waller Creek Working Grou

Diversity Within the Wildlife Profession in Alaska

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