Probable Culprit Research Articles

An investigation into the failure of API 5L X-46 grade ERW linepipes

The genesis of failure of 6.1 mm thick electric resistance welded (ERW) API 5L X-46 pipes during pretesting at a pressure equivalent to 90% of specified minimum yield strength (SMYS) was investigated. Cracks were found to initiate on the outer surface of the pipes in the fusion zone and propagate along the through-thickness direction. The presence of extensive decarburization and formation of a soft ferrite band within the fusion zone may have contributed to the nucleation of the cracks. Crack propagation was aided by the presence of exogenous inclusions entrapped within the fusion zone. Analysis of these inclusions confirmed the presence of Fe, Si, Ca, and O, indicating slag entrapment to be the most probable culprit.

Microemboli and Neurologic Dysfunction After Cardiovascular Surgery

Several recent studies have shown that cardiac surgery poses significant risks for negative neurologic and neu ropsychological outcome. Death and major stroke have become uncommon consequences of cardiac surgery, but more than two-thirds of the patients show evidence of neuropsychological dysfunction postoperatively. The mechanisms contributing to postcardiopulmonary bypass neuropsychological deficits are uncertain, and potentially there are many possible causative factors that may play a significant role in perioperative neuro logic injury. However, two major interrelated factors, hypoperfusion and emboli, are suggested as probable culprits. Perfusion is important because the level of global and focal cerebral blood flow during periods of high embolic risk will determine the amount of brain embolization as well as the localization of the lesions. Ultrasonically detected macroemboli have been re ported to be the best predictor of neurobehavioral outcome. Microemboli found in autopsy specimens may also be important predictors of negative outcome. The relationship between microemboli and changes in brain function, as detected by magnetic resonance spectroscopy, may provide further insight into the prob ability of the clinical expression of a neurobehavioral dysfunction after cardiac surgery. The incidence and severity of neuropsychological defi cits after cardiac surgery appear to be related to the delivery of macroemboli. The composition of the embo lus may be the most important determinant of the level and volume of focal injury, but the time of occurrence (ie, rewarming) of macroemboli during cardiopulmo nary bypass may also be important in determining the effect of emboli on neuropsychological outcome. How ever, the key variable in the manifestation of neurobe havioral dysfunction remains the location of the lesion site.

Boreholes in Mississippian spiriferide brachiopods and their implications for Paleozoic gastropod drilling

Bored specimens of the spiriferide brachiopod genera Brachythyris and Spirifer from several localities of the Mississippian Fort Payne Formation (Kentucky, USA) represent 7.0% of the total sampled population. The boreholes are typically single, complete, circular in plan view, and with their long axes perpendicular to the valve. These traits and stereotypy with respect to the pedicle valve and the fold and sulcus are consistent with a predatory/parasitic origin of the holes. The presence of platyceratid gastropods in the Fort Payne localities with bored brachiopods, the previously documented drilling abilities of these gastropods, and the occurrence of a platyceratid snail attached to specimen of a bored Devonian brachiopod, Atrypa, argue for platyceratids as the most probable culprits.

Antiphospholipid antibodies and infertility: fact or fallacy.

Some clinicians are convinced that antiphospholipid antibodies, including antibodies to any one of five-to-seven phospholipid antigens, are associated with infertility. Additionally, some clinicians recommend that infertile women who have antiphospholipid antibodies and are undergoing in-vitro fertilization should be treated with heparin to improve the rate of pregnancy. However, experts disagree regarding the relationship between antiphospholipid antibodies and infertility. There is also substantial evidence that treatment with heparin does not alter the rate of pregnancy following in-vitro fertilization. Why the confusion? Probable culprits include variation in study design and the selection of infertile patients. Another important problem is that assays for antiphospholipid antibodies other than anticardiolipin are not standardized. Before the real relationship between antiphospholipid antibodies and infertility is discovered, assays for antiphospholipid antibodies other than anticardiolipin must be standardized and properly designed studies conducted. Randomized, controlled trials must be done to determine if heparin should be recommended as an adjunctive treatment for in-vitro fertilization in women with antiphospholipid antibodies.

Emboli and Neuropsychological Outcome Following Cardiopulmonary Bypass.

The dramatic decline in mortality related to cardiac surgery has resulted in over 330,000 surgeries involving cardiopulmonary bypass (CPB) being performed yearly in the United States. Although few patients die as a result of cardiac surgery, over two thirds of the patients demonstrate evidence of acute neuropsychological dysfunction postoperatively. The potential mechanisms contributing to post-CPB neuropsychological deficits are many, but two major inter-related etiologic factors, hypo-perfusion and emboli, are suggested as the probable culprits. If embolism is the cause of the deficits, increasing cerebral perfusion would deliver more emboli and increase the amount and severity of injury. Conversely, if hypoperfusion is the cause of the injury, then decreasing brain blood flow to minimize embolic delivery would increase the likelihood of perfusion injury. By monitoring the carotid arteries of patients undergoing coronary artery bypass graft surgery, we have determined the frequency and quantity of embolic signals that occur during CPB. Although we have not been able to determine the nature of the embolus, gaseous or solid, we have demonstrated a relationship between the overall embolic load and the probability of having NP dysfunction. (ECHOCARDIOGRAPHY, Volume 13, September 1996)

Cerebral emboli and cognitive outcome after cardiac surgery

There have been major advancements in cardiac surgery over the past two decades, with a concomitant decrease in mortality and major morbidity. However, several recent studies have demonstrated that cardiac surgery poses significant risk for negative neurologic and neuropsychologic outcome. Although very few patients die as a result of cardiac surgery, more than two thirds of the patients demonstrate evidence of neuropsychologic dysfunction postoperatively. The mechanisms contributing to post-cardiopulmonary bypass neuropsychologic deficits are uncertain. However, two major interrelated etiologic factors, hypoperfusion and emboli, are suggested as probable culprits. It is important to define the relationship between these two putative mechanisms and postoperative neuropsychologic outcome in order to either prevent the problem or treat the effects of emboli or hypoperfusion. For example, if embolism is the cause of the deficits, increasing cerebral perfusion would deliver more emboli and increase the amount and severity of injury. Conversely, if hypoperfusion is the cause of the injury, then decreasing brain blood flow would increase the likelihood of injury. If both are important, their relative significance must be established, then one prevented and the effects of the other treated. This report discusses the methodology for detecting cerebral emboli during cardiac surgery. The incidence and severity of neuropsychologic deficits after cardiac surgery are discussed, as well as emboli in relation to composition and time of occurrence and their effect on neuropsychologic outcome.

Cyanobacteria and eukaryotic algae in sports turf and amenity grasslands: a review

A review is presented on the occurrence and role of cyanobacteria and eukaryotic algae in sports turf, especially golf curses, and on the problems arising when these organisms become abundant. The literature depends largely on observations in only a few countries, mainly Canada, New Zealand, U.K. and U.S.A., but problem growths are probably widespread. The genera reported to be conspicuous at times include Nostoc, Phormidium, Coccomyxa, Cosmarium, Cylindrocystis, Klebsormidium, Mesotaenium and Zygogonium. Conspicuous surface growths are probably most often related to unsatisfactory drainage or irrigation practices, but other factors such as fertilizer treatment (especially excess ammonium sulphate) have been implicated. These surface growths sometimes incorporate copious mucilaginous ‘slime’, which can be a serious hazard by causing people to slip. U.K. observations suggest that this is especially likely under acidic conditions, where Coccomyxa, Cylindrocystis and Mesotaenium are among the probable culprits.

The Merry Wives of Windsor, Q1: Provincial Touring and Adapted Texts

RECENT STUDIES OF SOME OF SHAKESPEARE'S bad or dubious quartos have renewed interest in their authority in transmission of text. Gary Taylor, example, in his edition of Henry V, sees quarto version of that play as the result of a reconstruction by memory of play as performed-as performed, moreover, in a severely abridged and adapted text, such as might have been used by a troupe of actors touring provinces. The probable theatrical origin of this text, though transmitted by memory, makes Q an historical document of far more authority than hypotheses of any twentieth-century scholar. This view of Quarto causes Taylor to introduce some significant variants into his edition of play. Like quarto version of Henry V, quarto of The Merry Wives of Windsor (1602) has also been thought to be an abridged and adapted play.2 It is about half as long as folio text (1,624 lines to 2,729),3 and it contains several intriguing omissions and transpositions. W. W. Greg, whose examination of this text in his 1910 edition established theory of memorial reconstruction, with actor who played Host as probable culprit, some years later noticed signs of abridgment and concluded that heavy cutting and excision of two boys' parts suggest deliberate adaptation.4 Still later he surmised that Quarto, though a reported text, was intended for acting, presumably in country. .. .5 William Green, too, argues that this text represents an unauthorized version of play reconstructed by memory a provincial acting troupe.6 And William Bracy and Robert Burkhart maintain that text has been deliberately adapted, probably from an authoritative manuscript.7 The provincial acting hypothesis is, of course, not new. In 1919 Pollard and

An explanation of hypertension produced by narrowing the renal artery.

In 1934 Goldblatt described a simple method ofproducing hypertension by bilateral narrowing of the renal arteries. The condition resembled human hypertensive disease in many ways. It seemed likely that understanding the mechanism involved would contribute to an explanation of the human disease. Groups headed by Page, Braun-Menendez, Pickering, and others seized upon a probable culprit, renin. This enzyme is found only in the kidney and acts upon a plasma protein to release a potent hypertensive agent, angiotensin. The results of infusing angiotensin mimic in most respects the hemodynamic changes of renal hypertension. Constricting the renal artery is followed by increased renin in the kidney. The work of Skeggs, Peart, Bumpus and Page, and Schweyzer which culminated in isolation, chemical description, and synthesis of angiotensin intensified study of this mechanism, and for a time it seemed likely that renal hypertension would seen be explained. Only the final step remained —finding increased renin or angiotensin in the blood ofrenal hypertensive animals.