Autonomic correlates of attention-deficit/hyperactivity disorder and oppositional defiant disorder in preschool children.

Numerous studies have revealed autonomic underarousal in conduct-disordered adolescents and antisocial adults. It is unknown, however, whether similar autonomic markers are present in at-risk preschoolers. In this study, the authors compared autonomic profiles of 4- to 6-year-old children with attention-deficit/hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD; n = 18) with those of age-matched controls (n = 20). Children with ADHD and ODD exhibited fewer electrodermal responses and lengthened cardiac preejection periods at baseline and during reward. Although group differences were not found in baseline respiratory sinus arrhythmia, heart rate changes among ADHD and ODD participants were mediated exclusively by parasympathetic withdrawal, with no independent sympathetic contribution. Heart rate changes among controls were mediated by both autonomic branches. These results suggest that at-risk preschoolers are autonomically similar to older externalizing children. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Field Evaluation of Crushed Glass–Dredged Material Blends

Based on the laboratory results reported in a companion paper, three crushed glass–dredged material (CG–DM) blends were prepared and evaluated in the field to explore the feasibility of using CG–DM blends in general, embankment and structural fill applications. A trailer-mounted pugmill successfully prepared 20/80, 50/50, and 80/20 CG–DM blends (dry weight percent CG content reported first) within a tolerance of ±5 dry % by weight of the targeted percentages. Blending criteria were routinely met at pugmill throughputs up to 1,500?m3/day. The constructed 20/80 CG–DM embankment was compacted to a minimum of 90% modified Proctor compaction, whereas the 50/50 and 80/20 CG–DM embankments were constructed to a minimum of 95% modified Proctor compaction. Twenty to 80% CG addition to DM resulted in 1.5–5.5?kN/m3 increases in field dry densities above 100% DM, densities not achievable with other DM stabilization techniques such as Portland cement, fly ash, and/or lime (PC/FA/lime) addition. CG substantially improved the workability of DM allowing construction with conventional equipment and three person crew while achieving very consistent and reproducible results during a timeline of frequent and heavy precipitation events. The 20/80, 50/50, and 80/20 CG–DM embankments were characterized by average cone tip resistances on the order of 1.0, 1.5, and 2.0?MPa, respectively. An environmental evaluation of 100% CG, DM and 50/50 CG–DM blend samples coupled with an economic analysis of a scaled-up commercial application illustrated that the CG–DM blending approach is potentially more cost effective than PC/FA/lime stabilization approaches. These features of CG–DM blending make the process attractive for use in urban and industrial settings.     

A general-purpose tunable landscape generator

The research literature on metaheuristic and evolutionary computation has proposed a large number of algorithms for the solution of challenging real-world optimization problems. It is often not possible to study theoretically the performance of these algorithms unless significant assumptions are made on either the algorithm itself or the problems to which it is applied, or both. As a consequence, metaheuristics are typically evaluated empirically using a set of test problems. Unfortunately, relatively little attention has been given to the development of methodologies and tools for the large-scale empirical evaluation and/or comparison of metaheuristics. In this paper, we propose a landscape (test-problem) generator that can be used to generate optimization problem instances for continuous, bound-constrained optimization problems. The landscape generator is parameterized by a small number of parameters, and the values of these parameters have a direct and intuitive interpretation in terms of the geometric features of the landscapes that they produce. An experimental space is defined over algorithms and problems, via a tuple of parameters for any specified algorithm and problem class (here determined by the landscape generator). An experiment is then clearly specified as a point in this space, in a way that is analogous to other areas of experimental algorithmics, and more generally in experimental design. Experimental results are presented, demonstrating the use of the landscape generator. In particular, we analyze some simple, continuous estimation of distribution algorithms, and gain new insights into the behavior of these algorithms using the landscape generator.     

Thermal Expansion of Y2SiO5 Single Crystals

The thermal expansion of Y₂SiO₅ crystals has been measured for the principal crystallographic directions and two orthogonal directions in the (010) plane in the temperature range 25° to 200°C. This monoclinic crystal has strongly anisotropic expansions with coefficients which range from 0.6 × 10⁻⁶/°C for [100] to 11.4 × 10⁻⁶/°C for [001]. Third-order polynomials have been calculated from the expansion curves. Data for the β angle and cell volume as a function of temperature are also given. The thermal expansion of Y₂SiO₅ crystals is not affected by doping with 5% Tb.     

Ionic requirements for the active ileal bile salt transport system

A new system of surface-induced profound hypothermia for infant cardiac operations has been developed in order to overcome problems inherent in the current techniques using crushed ice, water baths, and similar methods. The hypothermic chamber consists of two parts: a lower part, containing a refrigeration unit and a blower fan capable of lowering the air temperature in the chamber to -6 degrees C, and an upper part made of Plexiglas that has a completely detachable end to allow easy access to cannulas, the anesthesia hose, and the infant. A temperature panel recorder to monitor the infant's esophageal and rectal temperatures and the ambient chamber temperature is incorporated into the unit. Following evaluation in the animal laboratory, the hypothermic chamber has been successfully used in 10 infants without any complications attributable to the technique. This method provides a rapid and uniform drop of the body temperature and even skin cooling, eliminates the possibility of contact skin lesions, saves medical and paramedical personnel time in preparation of the infant and equipment, and allows observation of the child during the cooling phase. This hypothermic chamber has facilitated infant hypothermic operations.     

Preparation of III–V compounds by reduction of precursors

Stoichiometric polycrystalline InP, GaAs and (InGa)As were prepared by hydrogen reduction of phosphate and arsenate precursors precipitated from aqueous solution. These ill-defined phosphate and arsenate precipitates were dried and heated at elevated temperatures in a stream of pure hydrogen to produce the phosphides and arsenides. It was found necessary to introduce elemental phosphorus or arsenic in a heated region upstream of the reaction to establish the necessary pressure of P or As in the H₂ stream to inhibit the dissociation of the newly formed InP or GaAs.     

Estimating the statistical properties of crack growth for small cracks

A series of statistical studies were conducted on two sets of fatigue crack growth data which were generated under variable amplitude loading from cracks that initiated in 7475-T7351 Aluminum down in the bore of typical aircraft quality prepared holes. The study considered fatigue crack growth (life) behavior and fatigue crack growth rate behavior. Generally, the study showed that small crack growth behavior was similar to that observed for larger cracks and that a stress intensity factor parameter could be used to describe the mean trend of the fatigue crack growth rate behavior via a power law relationship.