Anthropogenic sources of arsenic and copper to sediments in a suburban lake,Northern Virginia

Mass balances of total arsenic and copper for a suburban lake in densely populated northern Virginia were calculated using date collected during 1998. Mass-balance terms were precipitation; stream inflow, including road runoff; stream outflow; and contributions from leaching of pressure-treated lumber. More mass of arsenic and copper was input to the lake than was output the 1998 lake-retention rates were 70% for arsenic and 20% for copper. The arsenic mass balance compared well with a calculated annual mass accumulation in the top 1 cm of the lake sediments; however, the calculated contribution of copper to the lake was insufficient to account for the amount of copper in this zone. Leaching experiments were conducted on lumber treated with chromated copper arsenate (CCA) to quantify approximate amounts of arsenic and copper contributed by this source. Sources to lake sediments included leaching of CCA-treated lumber (arsenic, 50%; copper, 4%), streamwater (arsenic, 50%; copper, 90%), and atmospheric deposition (arsenic, 1%; copper, 3%). Results of this study suggest that CCA-treated lumber and road runoff could be significant nonpoint sources of arsenic and copper, respectively, in suburban catchments.     

The use of predictive microbiology by the Australian meat industry

In Australia, the key regulatory body, the Meat Standards Committee (MSC) of the Agricultural and Resource Management Council of Australia and New Zealand (ARMCANZ) and the Export Meat Industry Advisory Council (EMIAC) have accepted in principle the usefulness of predictive microbiology for science-based regulation. The predictive microbiology approach is being used in a range of areas including hot-boning, distribution of meat, retailing of meat, fermentation, plant breakdowns and extended chilling regimes.     

A hub-and-spoke model of care: providing specialty care in patients' own communities

The authors describe how they used lessons learned in increasing office efficiency to improve primary care providers' ability to arrange for many specialty consultations and care within a reasonable driving distance for patients.     

Covalent attachment of gold nanoparticles to DNA templates

Functionalized gold nanoparticles have been covalently bound to internal, modified sites on double-stranded DNA. Gold nanoparticles coated with mercaptosuccinic acid or thioctic acid were bound to amino-modified thymine bases on double-stranded DNA. Visible absorption spectra, gel electrophoresis, and atomic force microscopy were used to analyze the products. Thiol groups were added to one end of the gold/nanoparticle product, which was then attached to a gold surface. This method has the potential to allow controlled placement of particles with subnanometer precision and to allow attachment of the product to fixed contacts for nanodevice fabrication.     

Use of a fixed-base driving simulator to evaluate the effects of experience and PC-based risk awareness training on drivers' decisions

Driver education classes were once seen as a remedy for young drivers' overinvolvement in crashes, but research results from the early 1970s were disappointing. Few changes in the content or methods of instruction occurred until recently, but this could change rapidly. Personal computers (PCs) can now present videos or photorealistic simulations of risky, cognitively demanding traffic scenarios that require quick responses without putting the participant at risk. As such programs proliferate, evaluating their effectiveness poses a major challenge. We report the use of a fixed-base driving simulator to study the effects of both experience on the road and PC-based risk awareness training on younger drivers' part-task simulator driving performance in risky traffic scenarios. We ran three groups of drivers on the simulator: one group first trained on the PC (younger, inexperienced drivers) and two groups who received no PC training (younger, inexperienced and experienced drivers). Overall, the younger, inexperienced drivers who were trained on a PC operated their vehicles in risky scenarios in ways that differed measurably from those of the untrained younger, inexperienced drivers and, more important, in ways that we believe would decrease their exposure to risk considering that, on average, their behavior was more similar to the behavior of the untrained, experienced drivers. More research is needed to demonstrate whether these findings apply on the open road to the larger population of younger drivers. However, at least initially, the research suggests that PC-based risk awareness training programs have the potential to reduce the high crash rate among younger, inexperienced drivers.     

Surveyance of disease frequency in a population by linkage to diagnostic laboratory databases. A system for monitoring the incidences of hyper- and hypothyroidism as part of the Danish iodine supplementation program

In Denmark an increase in iodine intake through salt iodization has been introduced in 1998. In parallel a program for surveyance of thyroid diseases in the population was developed as recommended by UNICEF and WHO. OBJECTIVE: To develop and evaluate a computer based system to identify and register new cases of hyper- and hypothyroidism in a well defined cohort, by linkage to diagnostic laboratory databases. DESIGN AND RESULTS: (1) Two sub cohorts for monitoring were defined (n=535,859), and evaluated to minimize loss of new cases. Collaboration was established with laboratories covering thyroid hormone analyses in the cohort; (2) a diagnostic algorithm was defined and evaluated against clinical practice; (3) evaluation of the laboratory methods employed by the four participating laboratories, to ensure they would reach the same diagnosis in a patient; (4) a register database was developed which used data imported from the laboratory databases to automatically identify previously unknown cases of hyper- and hypothyroidism and record diagnostic activity in the area. All parts of the registration were carefully evaluated. CONCLUSION: We describe for the first time a computer based system for prospective measuring the incidence rate of hyper- and hypothyroidism. The system is particularly useful for monitoring of iodine supplementation programmes.     

Development of a shortened center for epidemiological studies depression scale for assessment of depression in rheumatoid arthritis.

Objective: The purpose was to develop a short-form version of the Center for Epidemiologic Studies Depression Scale (CES-D) for the identification of persons with major depressive disorder (MDD) within a population with rheumatoid arthritis (RA). Study Design: Data were analyzed from 337 persons with RA. Forty-six participants met the diagnostic criteria for MDD; 291 participants were classified in the non-MDD category (including 21 participants with dysthymia and 18 participants with minor depressive disorder). A short-form version of the CES-D was developed, and multiple cutoff scores were examined. Results: A cutoff score of ≥5 from a 9-item, short-form CES-D was found to be generally as efficient as the more commonly used full-scale cutoff score of ≥16 for classifying participants with MDD within an RA population. Although the shortened CES-D scale (cutoff score ≥5) was slightly more sensitive, it also exhibited slightly less specificity than the full-scale cutoff score of ≥16. Conclusion: The results suggest that a short-form CES-D can be used to screen for MDD within an RA sample with a degree of efficiency that is generally comparable to that of the full-scale instrument. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Symmetry Definitions for Constraint Satisfaction Problems

We review the many different definitions of symmetry for constraint satisfaction problems (CSPs) that have appeared in the literature, and show that a symmetry can be defined in two fundamentally different ways: as an operation preserving the solutions of a CSP instance, or else as an operation preserving the constraints. We refer to these as solution symmetries and constraint symmetries. We define a constraint symmetry more precisely as an automorphism of a hypergraph associated with a CSP instance, the microstructure complement. We show that the solution symmetries of a CSP instance can also be obtained as the automorphisms of a related hypergraph, the k-ary nogood hypergraph and give examples to show that some instances have many more solution symmetries than constraint symmetries. Finally, we discuss the practical implications of these different notions of symmetry.     

Translational Covering of Closed Planar Cubic B-Spline Curves

Spline curves are useful in a variety of geometric modeling and graphics applications and covering problems abound in practical settings. This work defines a class of covering decision problems for shapes bounded by spline curves. As a first step in addressing these problems, this paper treats translational spline covering for planar, uniform, cubic B‐splines. Inner and outer polygonal approximations to the spline regions are generated using enclosures that are inside two different types of piecewise‐linear envelopes. Our recent polygonal covering technique is then applied to seek translations of the covering shapes that allow them to fully cover the target shape. A feasible solution to the polygonal instance provides a feasible solution to the spline instance. We use our recent proof that 2D translational polygonal covering is NP‐hard to establish NP‐hardness of our planar translational spline covering problem. Our polygonal approximation strategy creates approximations that are tight, yet the number of vertices is only a linear function of the number of control points. Using recent results on B‐spline curve envelopes, we bound the distance from the spline curve to its approximation. We balance the two competing objectives of tightness vs. number of points in the approximation, which is crucial given the NP‐hardness of the spline problem. Examples of the results of our spline covering work are provided for instances containing as many as six covering shapes, including both convex and nonconvex regions. Our implementation uses the LEDA and CGAL C++ libraries of geometric data structures and algorithms.     

Visualizing “typical” and “exotic” Internet traffic data

The threat of cyber attacks motivates the need to monitor Internet traffic data for potentially abnormal behavior. Due to the enormous volumes of such data, statistical process monitoring tools, such as those traditionally used on data in the product manufacturing arena, are inadequate. “Exotic” data may indicate a potential attack; detecting such data requires a characterization of “typical” data. We devise some new graphical displays, including a “skyline plot,” that permit ready visual identification of unusual Internet traffic patterns in “streaming” data, and use appropriate statistical measures to help identify potential cyberattacks. These methods are illustrated on a moderate-sized data set (135,605 records) collected at George Mason University.