Quantification of different effects occurring during fatigue tests on bituminous mixtures

Quantification of different effects (nonlinearity, heating, thixotropy, and fatigue) occurring during fatigue tests on bituminous mixtures is presented in this paper. A focus is given on the nonlinearity phenomenon. Continuous fatigue tests and a test with specific protocol (called fatigue tests to estimate biasing effects) were performed in tension/compression mode on cylindrical samples of the same material. The analysis of results reveals that reversible effects (nonlinearity, heating, and thixotropy) are important (more than 90% decrease at 100,000 cycles for a strain amplitude of 100 μm/m at 10 Hz) and cannot be ignored when interpreting classical fatigue tests. The nonlinearity effects respect the time‐temperature superposition principle, and they are more pronounced at “high” temperature (at the same frequency). Direction of nonlinearity curve in the Cole‐Cole axes is shown to be independent of temperature and frequency for the considered range.     

Precisely Controlled Microsphere Design via Visible‐Light Cross‐Linking of Functional Prepolymers

A new strategy for particle synthesis is enabled by utilizing modern synthetic, polymer, and photochemical techniques to facilitate the synthesis of highly narrow–disperse multifunctional microspheres from visible‐light induced crosslinking of prepolymers in both a single and dual polymer system. The approach requires no stabilizers, bases, or initiators, and proceeds at ambient temperature to yield microspheres with a tunable size range (0.25–5 µm) in less than 4 h, depending largely on solvent composition, but also polymer concentration (2–10 mg mL^?1), ratio, and irradiation intensity (3–20 W). Critically, the visible‐light induced dimerization reaction exploited herein enables simple functional particle syntheses via a single polymer system. Underpinned by an in‐depth kinetic analysis of the particle formation as well as a detailed small molecule study, the mechanism for particle formation is also elucidated. Importantly, inherent advantages of the system are exploited for surface functionalization of residual acrylate and hydroxyl groups (generating inherently fluorescent particles).     

Effects of club size in the provision of public goods. Network and congestion effects in the case of the French municipalities

The article formalizes and measures the impact of club size on the quality of the public good provided to its members. Under a general framework we describe various functional forms that allow either network or crowding effects. Mechanisms of provision are that of a political process in which both the demand and the supply sides are considered. Estimations use the whole set of French municipalities. The supply model performs better than the demand model in the case of small municipalities, while for large cities the demand model has higher explanatory power. In so far as impact of city size on the quality of club goods is concerned, crowding does appear, but it does so in different patterns. For small towns marginal congestion first decreases then increases with population. Marginal congestion is decreasing for cities of intermediate size. For larger cities no significant effects are observed. Received: 27 June 2000 / Accepted: 20 August 2001 RID="*" ID="*" We have received particularly helpful comments from the editor-in-chief and two anonymous referees. We also thank Danièle Moret-Bailly for her friendly computational assistance.     

An embedded strong discontinuity model for cracking of plain concrete

A numerical model formulated within the framework of a nonsymmetric strong discontinuity approach for fracture simulations of plain concrete is presented. The model is based on the fixed crack concept and makes use of the concept of the elements with embedded discontinuities. Discontinuity segments of individual elements are considered to form a C⁰-continuous path. Enforcement of continuity of the crack path across adjacent elements is established by a partial domain crack tracking algorithm. Orientation of individual crack segments is derived from a nonlocal strain field. The capabilities of the model are shown by means of numerical examples.     

Stearic acid oxidation in the Alaskan red-backed vole: effects of cold and norepinephrine

Amphibian populations appear to be declining around the world. Although there is no single cause, one factor may be pollution from heavy metals. As a result of mining in the Silver Valley of Idaho, heavy metals have been released into habitats containing many species of sensitive organisms, including spotted frogs (Rana luteiventris). While the gross extent of pollution has been well documented, the more subtle behavioral effects of heavy metals such as lead, zinc, and cadmium are less well studied. We tested the effects of heavy metals on the short-term survival (LC50) of spotted frog tadpoles. Compared to single metals, metals presented together were toxic at lower doses. We also raised the tadpoles in outdoor mini-ecosystems containing either a single heavy metal or soil from an EPA Superfund site in the Silver Valley known to be composed of numerous heavy metals. Exposure to Silver Valley soil resulted in delayed metamorphosis. We tested the ability of metal-exposed tadpoles to detect and respond to chemical cues emanating from predacious rainbow trout. We found that high levels of Silver Valley soil, medium levels of zinc, and medium and high levels of lead resulted in a decreased fright response. Low levels of cadmium, zinc, and lead did not cause a significant effect, but low levels of soil did result in a decreased fright response. Heavy metals may alter interactions between tadpoles and their predators.     

The recovery of potassium chloride from Dead Sea brines by precipitation and solvent extraction

A process is proposed for the recovery of potassium from brines by precipitation as potassium perchlorate, followed by conversion to potassium chloride by liquid anion exchange with a tertiary amine in the form of its hydrochloride. Regeneration of the amine salt is effected by means of lime and hydrochloric acid. The process was tested on Dead Sea brine, containing 13 g/l KCl. Precipitation at 30 °C gave a 40% yield of potassium, cooling to 0 °C increased the yield to over 80%. The anion exchanger used was the hydrochloride of trioctylamine dissolved in toluene; this performed satisfactorily and phase separation was easy. A separation factor of 130 was obtained for the ClO₄^?/Cl^? separation. Regeneration of the amine was tested with various bases.     

Evaluation of several finishes on severely weathered wood

Alkyd-, oil-modified-latex-, and latex-based finishes were applied to severely weathered western redcedar and redwood boards that did not have any surface treatment to ameliorate the weathered surface prior to painting. Six finishes were evaluated annually for 11 years for cracking, flaking, erosion, mildew growth, discoloration, and general appearance. Lowsolids-content latex finishes that contained about 10% raw linseed oil and 11% acrylic resin (i.e., the oil-modified latex finishes) performed better on badly weathered wood than did the alkyd and the other latex finish, even after 11 years. Latex finishes that contained raw linseed oil probably stabilized the weathered surface and plasticized the finish. The stabilization of the wood surface and the flexibility of the finish throughout its service life are the important factors in finish performance on these weathered substrates. Forest Products Laboratory, One Gifford Pinchot Drive, Madison, WI 53705-2398. The use of trade or firm names in this publication is for reader information and does not imply endorsement by the U.S. Department of Agriculture of any product or service. The Forest Products Laboratory is maintained in cooperation with the University of Wisconsin. This article was written and prepared by U.S. Government employees on official time, and it is therefore in the public domain and not subject to copyright.     

Relation between self- and other-acceptance and its moderation by identification.

Although psychologists and lay people share a common belief that positive self-regard is associated directly with positive regard for others, the influence of parameters such as the nature of the others and their perceived similarity to the self rarely is considered. To investigate the influence of the degree of identification with the others who are rated on self–other correlations, we examined the relation of self-ratings to ratings of same- and opposite-sex others in 60 preadolescent boys and 69 preadolescent girls. Each subject rated himself or herself and 8–20 classmates on 7 personality variables. Favorable self-ratings and ratings of same- and opposite-sex others were significantly positively associated in both groups: Girls exhibited similar self–other relations when rating same- and opposite-sex others; boys identified more strongly with their sex roles than girls and exhibited a stronger relation between self- and other-ratings when the others were of the same sex. We concluded that a positive relation between self- and other-acceptance is fairly robust, but the magnitude of the relation is moderated by the degree of identification with those rated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)