Effects of simulated employment and recreation on drug taking: A behavioral economic analysis.

With a within-subject design, this study examined the effects of varying response requirement (price) to obtain puffs on a cigarette in the presence and the absence of an opportunity (a) to make money in Experiment 1 (a simulation of employment) and (b) to engage in recreational activities (a simulation of recreation) in Experiment 2. The results indicated that cigarette smoking (number of puffs) decreased and response output increased as price increased. Also, cigarette smoking and response output decreased with the introduction of competing reinforcers at all prices. Lastly, the greatest reduction in cigarette smoking resulted from the combined effects of these two factors. Overall, these data suggest that drug use can be reduced by increasing price or enriching the environment and that maximal reductions result from the simultaneous application of both factors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The ability of low doses of caffeine to serve as reinforcers in humans: A replication.

Eleven coffee drinkers were given concurrent access to placebo coffee versus coffee to which 25 or 50 mg of caffeine had been added. The 25-mg dose reliably served as a reinforcer in 2 participants and the 50-mg dose served as a reinforcer in 5 participants. When only placebo coffee was available, participants reported more headaches and drowsiness and less stimulation, alertness, and relaxation. The occurrence of headache and drowsiness with placebo coffees predicted subsequent caffeine reinforcement. These results replicate our prior findings that low doses of caffeine can reliably serve as a reinforcer in a subsample of caffeine users and that caffeine withdrawal predicts caffeine reinforcement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Optimal expansion of a hydrodesulfurization process

The problem solved is: Given deterministic sales forecasts and production requirements over a future time horizon, and a finite set of possible plant expansions to an existing process, when and how should the chemical plant be expanded in order to satisfy the production requirements and maximize the present worth of net profit? A branch and bound procedure combined with nonlinear programming was developed, and applied to a hydrodesulfurization plant to illustrate the technique, its advantages, and its limitations.     

Recent Advances in Facial Appearance Capture

Facial appearance capture is now firmly established within academic research and used extensively across various application domains, perhaps most prominently in the entertainment industry through the design of virtual characters in video games and films. While significant progress has occurred over the last two decades, no single survey currently exists that discusses the similarities, differences, and practical considerations of the available appearance capture techniques as applied to human faces. A central difficulty of facial appearance capture is the way light interacts with skin—which has a complex multi‐layered structure—and the interactions that occur below the skin surface can, by definition, only be observed indirectly. In this report, we distinguish between two broad strategies for dealing with this complexity. “Image‐based methods” try to exhaustively capture the exact face appearance under different lighting and viewing conditions, and then render the face through weighted image combinations. “Parametric methods” instead fit the captured reflectance data to some parametric appearance model used during rendering, allowing for a more lightweight and flexible representation but at the cost of potentially increased rendering complexity or inexact reproduction. The goal of this report is to provide an overview that can guide practitioners and researchers in assessing the tradeoffs between current approaches and identifying directions for future advances in facial appearance capture.     

State of the Art on Stylized Fabrication

Digital fabrication devices are powerful tools for creating tangible reproductions of 3D digital models. Most available printing technologies aim at producing an accurate copy of a tridimensional shape. However, fabrication technologies can also be used to create a stylistic representation of a digital shape. We refer to this class of methods as ‘stylized fabrication methods’. These methods abstract geometric and physical features of a given shape to create an unconventional representation, to produce an optical illusion or to devise a particular interaction with the fabricated model. In this state‐of‐the‐art report, we classify and overview this broad and emerging class of approaches and also propose possible directions for future research.     

Angular distribution of fluorescence from dye-filled capillaries

We studied the angular distribution of fluorescence from a small, lossy capillary filled with a laser-dye solution. We found that the fluorescence is isotropic for the liquid core and that, far from the liquid-solid phase transition, this isotropy shows no temperature dependence. This result, an extension of studies with solid cylinders, is at variance with theoretical expectations for solids as well as with previous reports by other investigators but is explained by the motion of the molecules in the liquid. Therefore the optimal viewing angle for capillary zone electrophoresis experiments is near 90° because the elastic scattering of the incident laser light is at or near a minimum for these small capillaries. This reduces contamination of the fluorescence signal as a result of stray laser light in the optical system.     

An algorithm for identifying nonsystematic delay-discounting data.

[Correction Notice: An erratum for this article was reported in Vol 16(4) of Experimental and Clinical Psychopharmacology (see record 2008-10619-006). Several misprints occurred and should read as follows: 1) Warren K. Bickel is with the University of Arkansas for Medical Sciences. 2) The first sentence in the abstract should read "Several discounting studies have used the R2 measure to identify data with poor fits to a mathematical discounting model as nonsystematic data to be eliminated." 3) In Table 2, the last row of column one should read "Madden opioid." 4) In the last line of the caption of Figure 2, "though" should read "through."] Several previous discounting studies have use the R2 measure to identify data sets with poor fits to a mathematical discounting model as nonsystematic data to be eliminated before further analyses are conducted. Data from three previous delay-discounting studies (six separate groups, with a total of 161 individuals) were used to demonstrate why using R2 to assess the fits of discounting data is problematic. A significant, positive correlation between discounting rate parameter and R2 was found in most groups, showing that R2 is more stringent as a measure of fit for low discounting rates than for high discounting rates. Furthermore, it is suggested that identifying nonsystematic data based on any measure of fit to a mathematical discounting model may be problematic because it confounds discounting rate comparison with the issue of discounting model assessment. Therefore, a model-free method to identify nonsystematic data is needed. An algorithm for identifying nonsystematic data is presented that is based on the expectation of a monotonically decreasing discounting function. This algorithm identified 13 cases out of the 161 reanalyzed data sets as nonsystematic. These nonsystematic data are presented, along with examples of data not identified as nonsystematic. This algorithm, or modifications of it, may be useful in a variety of human and nonhuman animal discounting studies (e.g., delay discounting, probability discounting) as an alternative to the R2 measure for identifying nonsystematic data. The algorithm may be used in empirical investigations to improve discounting methodology, and may be used to identify outliers to be removed from analyses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Messtechnische Überwachung extern vorgespannter Betonbrücken

Monitoring of reinforced concrete bridges retrofitted by external tendons An established retrofitting method for bridges with deficits in their load bearing capacity is the installation of external tendons to increase the lifespan of the structure. A critical detail of the retrofitting is the anchorage block, where significant forces have to be introduced into the existing superstructure. Therefore, the anchorage blocks of three bridges in Hessen were monitored. They were fitted with extensometers, strain gauges were installed on prestressing rods and the temperature was recorded. Furthermore alert protocols were established, to detect potentially critical situations. The effects of different construction stages were tracked. The influence of short‐ and long‐term temperature changes on the readings was assessed. In summary, the monitoring provided valuable insights into the structural interaction between the existing superstructure and the elements of the retrofitting.     

Querkraftwiderstand betonstabbewehrter Bauteile ohne Querkraftbewehrung

Shear Strength of Concrete Elements reinforced by prestressed Concrete Bars The shear strength of commonly reinforced concrete elements without shear reinforcement has been extensively studied and several semi‐empirical approaches for the determination of ultimate shear loads have been published. It seems to be necessary to prove the validity of these approaches for concrete elements reinforced with materials with a bi‐linear stress‐strain diagram in the elastic range. Prestressed Concrete Bars (PCB) show a distinct non‐linear behavior after decompression. Thus, they are especially suitable for a comparison with common reinforcement. The present article describes tests on the shear strength of concrete elements reinforced with PCBs. The results obtained are compared with the code DIN 1045‐1.