Role Of Strength Research Articles

Superheroes, monsters, and babies: roles of strength, destruction and vulnerability for emotionally disturbed boys

Superheroes, monsters, and babies: roles of strength, destruction and vulnerability for emotionally disturbed boys

On the role of strength and location of Brønsted acid sites for ethylamine synthesis on mordenite catalysts

The elementary steps of alkylation of ammonia with ethanol and the role of the strength and location of the acid sites of the mordenite catalysts were investigated by means of in situ i.r. spectroscopy, temperature-programmed desorption and kinetic measurements. Ethanol and ammonia have access to all Brønsted acid sites of the mordenites investigated. From the products only monoethylamine reached all acid sites, while di- and triethylamine sorbed only on 60% and 45% of the sites, respectively. The Brønsted acid sites of HNa-mordenites are exclusively located in the main channel up to an hydrogen exchange degree of 60%. Only at higher exchange degrees are the sites in the side pockets also exchanged. These latter acid sites apparently contribute significantly to the overall rate of amination. Mordenite with a high concentration of Na + ions (low H + exchange degree) stabilize ammonium less than those with a low Na + concentration. This leads to more ethene produced during the amination reaction. While some diethyl ether is formed during amination, the alcohol and not the ether is the primary alkylating agent.

Strength Testing Archaeological Ceramics: A New Perspective

The measurement of ceramic strength is an important source of evidence for assessing any pottery technology. However, the adoption of strength testing within comprehensive ceramic analyses in archaeology has been hindered by the absence of a reliable format for testing archaeological specimens. This paper presents results of research undertaken to develop the ball-on-three-ball test, which measures the tensile strength of archaeological, ethnographic, and experimental ceramics in biaxial flexure. Laboratory experiments demonstrate that the test produces reliable and accurate results largely unaffected by the irregularities of sherd-shaped specimens. In an example from the prehistoric Southwest, strength tests are used to investigate technological change in the Cibola White Ware sequence and the role of strength in the formation of archaeological assemblages. It is suggested that the development of a versatile, dependable technique can help to move strength testing out of experimental laboratories and into mainstream ceramic analyses.

Hamstring Muscle Injury: The Influence of Strength, Flexibility, Warm-Up, and Fatigue

Hamstring muscle injury is a complex problem for athletes, physicians, physical therapists, and athletic trainers. This injury tends to recur and to limit participation in athletic competition. The etiology of hamstring muscle injury continues to be confusing and incomplete for clinicians and researchers. The purposes of this paper are: 1) to review briefly hamstring muscle group anatomy and function, 2) to review the clinical and animal research literature concerning the role of strength, flexibility, warm-up, and fatigue in hamstring muscle injury, 3) to present an evaluation and rehabilitation scheme for hamstring muscle injury, 4) to describe a theoretical multiple factor hamstring injury model, and 5) to offer recommendations concerning prevention of hamstring muscle injury. During preseason screening and rehabilitation following hamstring muscle injury, clinicians should consider the influence of hamstring strength, flexibility, warm-up, and fatigue on muscle performance. Additional research concerning these factors is recommended. J Orthop Sports Phys Ther 1992;16(1):12-18.

Acquisition of competence for floral development in Nicotiana buds

Grafting experiments were used to investigate the relative roles of strength of flowering signal(s) and competence of buds to respond to flowering signal(s) in the development of photoperiodic and day-neutral species of Nicotiana. At the time of commitment to floral development, a flowering signal (inhibitory or promotive) could reach a critical level or terminal buds could gain competence to perceive and-or respond to an existing signal. The latter hypothesis appears to be true for day-neutral N. tabacum L. cv. Wisconsin 38, while signal strength appears to be a more critical factor for long-day N. silvestris L. Nicotiana tabacum and N. silvestris differ in terms of signal intensity at anthesis of the terminal flower. Stocks of N. silvestris promote more rapid flowering in seedling scions of both genotypes. Terminal buds of seedlings of both genotypes have the same competence to respond to the signal affecting floral development. The competence of the terminal bud of both species to respond to this signal(s) changes as a function of age.

Role of strength of hypothalamic stimulation in production of an antitumor effect

Role of strength of hypothalamic stimulation in production of an antitumor effect

Factors Involved in Success or Failure of Arterial Grafts

Fig. 1. —This illustration is concerned with the role of the elastica. Besides its normal functions, its strength role and its ultimate fate in implants are discussed. The first series of curves represents a theoretical concept (Burton) of relative tensile properties of elastic tissue and collagen. One notes that there is little limitation to stretch when tension is applied to the elastic fiber short of its breaking point. Collagen, on the other hand, shows limited extension and considerably greater resistance to stress. The next three tracings represent experimental findings on the tensile properties of an untreated artery and on tubes which are predominantly composed of either elastin or collagen. The last two materials mentioned were derived from arteries by chemical and enzymatic treatment. Their tension-elongation curves coincide remarkably well with the theoretical stress curves previously shown. The two photomicrographs, below, deal with the fate of elastic tissue in an initially