OBJECTIVE To examine relationships between parenting behaviors, parent-child relationship, and moderating effects of age on youth substance use among a community sample of African-American mothers who use crack cocaine and their children (12-17 years). METHODS Maternal-child dyads (n = 208) were recruited through street outreach and snowball sampling and completed interviews about substance u...

In recent years, there has been a resurgence of activity surrounding biolinguistics along with a parallel, renewed interest in the connections between language and evolution. To be sure, from one standpoint it has often been said, quite correctly, that linguistic science just is biology: the study, however abstract, of a particular, apparently species-specific human trait: knowledge of language...

in this paper, the crack detection and depth ratio estimation method are presented in beamlikestructures using elman networks. for this purpose, by using the frequencies of modes asinput, crack depth ratio of each element was detected as output. performance of the proposedmethod was evaluated by using three numerical scenarios of crack for fixed-simply supportedbeam consisting of a single crack...

An infinite elastic medium with a planar crack is considered. The crack is subjected to the pressure of fluid injected at a point on the crack surface. Description of the crack growth is based on the lubrication equation (balance of the injected fluid and the crack volume), the equation for crack opening caused by fluid pressure on the crack surface, the Poiseuille equation related local fluid ...

An assessment of the plasticity-induced crack-closure concept is made, in light of some of the questions that have been raised on the validity of the concept, and the assumptions that have been made concerning crack-tip damage below the crack-opening stress. The impact of using other crack-tip parameters, such as the cyclic crack-tip displacement, to model crack-growth rate behavior was studied...

poor stand establishment of canola (brassica napus l.) under flatland mechanized planting and crust-forming soil is a major problem for farmers in central iran. previous research there showed that irrigated cotton emergence on crust-forming soils under flatland planting can be significantly improved using a double-disk planter with zero-pressure press wheel tires and no crust-breaking. in that ...

Fatigue crack growth can be strongly influenced by crack closure, i. e., the contacting of the opposing faces of a fatigue crack above the minimum load in a loading cycle. This crack closure shields the crack tip from the full stress field, but different views are held regarding the extent of this shielding. The type of closure, whether it be plasticity-induced, or roughness-induced may also pl...

Organism is a multi-level and modularized complex system that is composed of numerous interwoven metabolic and regulatory networks. Functional associations and random evolutionary events in evolution result in elusive molecular, physiological, metabolic, and evolutionary relationships. It is a daunting challenge for biological studies to decipher the complex biological mechanisms and crack the ...

our ancestors without fear, worry and anxiety are not our ancestors, as organisms without defense systems were extinct. therefore, while behavior such as fear and anxiety are useful to prevent harm, the exaggerated form, that is, anxiety disorders, has more costs than benefits. likewise, while a panic attack is a normal and useful response in the face of life-threatening danger, a panic disorde...