The detailed structure of delamination fracture surfaces in graphite/epoxy laminates

Delamination fracture surfaces of angle-ply graphite/epoxy specimens failed in tension were studied in the SEM. The fracture surfaces contain resin-rich and resin-poor areas, with the former showing imprints from fibres while the latter show debonded fibres. A delamination crack propagates in the outer parts of the plies adjacent to the resin-rich interlaminar region and alternates from one ply to the adjacent ply and back as it propagates. The serrations formed in between fibres in the outermost parts of plies are tilted. The sense of the tilt is in agreement with the direction of the major tensile principal stress. The delamination is suggested to proceed in steps including debonding of fibres, crack opening by the major principal tensile stress and linking together of these fractures.     

Kringle 2 mediates high affinity binding of plasminogen to an internal sequence in streptococcal surface protein PAM

Many cells express receptors for plasminogen (Pg), although the responsible molecules in most cases are poorly defined. In contrast, the group A streptococcal surface protein PAM contains a domain with two 13-amino acid residue long repeated sequences (a1 and a2) responsible for Pg binding. Here we identify the region in Pg that interacts with PAM. A radiolabeled proteolytic plasminogen fragment containing the first three kringles (K1-K3) interacted with streptococci expressing PAM or a chimeric surface protein harboring the a1a2 sequence. In contrast, plasminogen fragments containing kringle 4 or kringle 5 and the activable serine proteinase domain failed to bind to PAM-expressing group A streptococci. A synthetic and a recombinant polypeptide containing the a1a2 sequence both bound to immobilized recombinant K2 (rK2) but not to rK1 or rK3. The interaction between the a repeat region and rK2 was reversible, and rK2 completely blocked the binding of Pg to the a1a2 region. The binding of the a repeat containing polypeptide to K2 occurred with an equilibrium association constant of 4.5 x 10(7) M-1, as determined by surface plasmon resonance, a value close to that (1.6 x 10(7) M-1) calculated for the a1a2-Pg interaction. Inhibition experiments suggested involvement of the lysine-binding site of K2 in the interaction. These data demonstrate that K2 contains the major Pg-binding site for PAM, providing the first well defined example of an interaction between an internal Pg-binding region in a protein and a single kringle domain.     

Contribution of prostaglandins to the adenosine triphosphate-induced contraction of rabbit urinary bladder

1 Adenosine 5'-triphosphate (ATP) produced an initial rapid, phasic contraction and a later, slowly developing tonic contraction in the isolated detrusor of the rabbit but mainly a rapid, phasic response in the guinea-pig bladder. 2 Electrical field stimulation elicited only a rapid, phasic contraction in both rabbit and guinea-pig bladders. 3 Prostaglandin synthesis inhibition by means of indomethacin and suprofen abolished the tonic response to ATP in the rabbit detrusor, leaving the phasic part of the contraction almost unaffected. The ATP-induced contraction in guinea-pig bladder was not influenced by indomethacin. 4 The contractile response of rabbit urinary bladder to prostaglandins F2 alpha and E2 and to carbachol were not significantly influenced by indomethacin. The contractions induced by the prostaglandins were similar to the tonic response to ATP. 5 Tetrodotoxin, atropine, phentolamine, and theophylline did not alter the ATP-induced contraction. However, the calcium antagonists, nifedipine and nimodipine, abolished the phasic ATP response and greatly reduced the tonic part of the contraction. 6 Tachyphylaxis occurred on repeated addition of ATP; the response to field stimulation was progressively reduced only after indomethacin pretreatment. 7 ATP and prostaglandins may contribute to the non-adrenergic, non-cholinergic component of the excitation of rabbit and guinea-pig bladder.     

Creativity and aggression.

We studied problems of identification in an experiment using a meta-contrast design. The first stimulus in the pair (A) was the word I shown subliminally. The second stimulus (B) depicted an aggressor and a victim facing each other. To manipulate the subject's identification, the subliminal A was flashed either on the victim or on the aggressor, or was completely withheld. Subjects were 28 16-year-olds of both sexes. They also took a perceptgenetic (PG) test measuring creativity and a test on anxiety and defensive strategies as revealed in the perceptual process (the meta-contrast technique or MCT). It was predicted that creative subjects would identify more openly with the aggressor than noncreative ones, when I was presented on the aggressor. Differences in the use of defenses were also expected. The results supported the predictions. It was concluded that creative subjects are more self-reliant than noncreative ones, more inclined to believe in the value of private impressions and ideas. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibition of phosphatases and increased Ca2+ channel activity by inositol hexakisphosphate

Inositol hexakisphosphate (InsP6), the dominant inositol phosphate in insulin-secreting pancreatic beta cells, inhibited the serine-threonine protein phosphatases type 1, type 2A, and type 3 in a concentration-dependent manner. The activity of voltage-gated L-type calcium channels is increased in cells treated with inhibitors of serine-threonine protein phosphatases. Thus, the increased calcium channel activity obtained in the presence of InsP6 might result from the inhibition of phosphatase activity. Glucose elicited a transient increase in InsP6 concentration, which indicates that this inositol polyphosphate may modulate calcium influx over the plasma membrane and serve as a signal in the pancreatic beta cell stimulus-secretion coupling.     

Stillbirth is no longer managed as a nonevent: a nationwide study in Sweden

BACKGROUND: Giving birth to a stillborn child is a tragedy. The aim of this study is to investigate the meeting of mothers with their stillborn children and the women's experiences of support during and after the delivery. METHODS: In a nationwide study in Sweden, data from 636 women who gave birth to a stillborn or live baby were collected by means of an anonymous postal questionnaire in 1994. RESULTS: Among the 314 women who gave birth to a stillborn child, nearly every mother had seen her child, and 80 percent had carressed her baby. More than 90 percent of the mothers stated that the medical staff showed respect, and about 80 percent of the mothers stated that staff exhibited tenderness toward their dead children. The mother's assessment of respect and tenderness to her child by medical staff was almost identical between stillbirths and live births. Nearly 70 percent of the women reported that the hospital had good routines to support mothers of stillborn children. Feelings of sadness and having been deeply hurt or angered by the medical staff's behavior were reported by 37 percent of the women. A difficult balance is still to be achieved between women being forced to encounter the baby when not yet ready versus others who wish the staff had given more encouragement. The value of properly taken photographs is described. CONCLUSIONS: Treating stillbirth as a nonevent has been largely, if not entirely, abandoned in Sweden. Most mothers of a stillborn child experience that the medical staff treat their dead children appropriately.     

Muscle injury in repetitive motion disorders

Documentation of causality between repetitive motions and musculoskeletal disorders calls for detailed understanding of the exposure variables and the corresponding physiologic responses in the biologic tissues. Quantification of the kinetics in some jobs characterized by repetitive motions is summarized with the physiologic responses in the muscles. Muscle activity pattern was studied in different shoulder muscles or muscle parts, and in elbow and wrist flexor muscles. Activity pattern was dependent on the kinetics of the work requirements. This holds true for the compound electromyographic signal and for single motor units. Low threshold motor units have been identified that are recruited continuously, the so called Cinderella fibers. The physiologic consequences of prolonged muscle fiber activity are reviewed, revealing mechanisms for the development of necrotic changes in the muscle, which support the likelihood of work relatedness for musculoskeletal disorders.     

The determination of optimum accelerating factors for successive overrelaxation on an equidistant and non-equidistant rectangular net

A modification to the successive overrelaxation iterative procedure for solving elliptic partial differential equations is presented. The modified method is based on an extension of Brazier's nodal overrelaxation method in one dimension, characterised by the use of a different overrelaxation factor for each point in the net. The extension to several dimensions make use of the separability of the variables for the error distribution. Thus the optimum one dimensional results are directly used in the several dimensional problem.The present method has been examined in one and two dimensions, for equidistant and non-equidistant nets. The computational time required to obtain a given accuracy for a solution was found for all two dimensional cases to be half (or less) of that required by conventional methods.