Dendrite morphology of several steady state unidirectionally solidified iron base alloys

The experimental data are presented of the dendrite morphology of steady state unidirectionally solidified steels. The dendrite arm spacings were correlated with the equation A =KR ^mG^mwhereR is the growth rate and G the temperature gradient. The exponentsm andn for the primary arms are fairly close to the theoretical values (m = -0.25,n = -0.5). For the secondary arms they are about the same (-0.4). The primary arm spacings do not depend much on composition. The secondary arm spacings, however, decrease at fixed carbon content with increasing content of substitutional elements, and they were found to be smaller in a steel freezing as ferrite compared to steels freezing as austenite. All the authors were with Max-Planck Institut für Eisenforschung, 4 Düsseldorf 1, Max-Planck-Str. 1, Germany, at the time this investigation was carried out.     

Pharmacokinetics and pharmacodynamic effects of the angiotensin II antagonist valsartan at steady state in healthy, normotensive subjects

The Salford static knee instrument (SSKI) was developed to determine the quantitative assessment of the human knee joint in vivo by utilizing the technique of applied displacement and measurement of resistive load as proposed by Butler et al. (1). The instrument was used in parallel with the device developed by Al-Turaiki (2) which utilized the opposite method of assessment. The objective of the research was to examine which of the two techniques provided the more reliable and accurate method of knee assessment. Fourteen patients with suspected isolated rupture of the anterior cruciate ligament (ACL) were subjected to anterior-posterior drawer testing on both devices. The results showed that each instrument produced results which confirmed the clinical diagnosis by indicating a significant decrease in anterior stiffness when comparing the injured and uninjured knees. [SSKI device (p = 0.000) and Al-Turaiki (2) device (p = 0.002) statistical significant difference testing with Bonferonni Alpha correction p = 0.0125]. The results showed the Salford static knee instrument indicated a 58 per cent decrease in anterior stiffness and the Al-Turaiki (2) device a 35 per cent decrease when comparing the injured and uninjured knees. In conclusion it is suggested that the application of displacement and measurement of load as proposed by Butler et al. (1) may be the most appropriate technique for precise clinical diagnosis of pathological human knee joint instability.     

The effects of high intensity intermittent sound on performance, feeling and physiology.

There has been in recent literature some evidence indicating that intermittent sound as opposed to steady sound sources has a more disturbing effect on Ss. This paper includes those studies which have appeared since 1950 and indicates that high intensity or intermittent sound generally produces symptoms of discomfort, instability, and distraction. In addition decrements in performance may be related to the level of the sound as well as its intermittency. Changes in blood pressure, respiration, EEG, pulse rate, etc., as a result of sound have been reported in some studies. Some theoretical issues are included in the discussion. 80 refs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparing the effects of aging and background noise of short-term memory performance.

Paired associate recall was tested as a function of serial position for younger and older adults for five word pairs presented aurally in quiet and in noise. In Experiment 1, the addition of noise adversely affected recall in young adults, but only in the early serial positions. Experiments 2 and 3 suggested that the recall of older adults listening to the words in quiet was nearly equivalent to that of younger adults listening in noise. In Experiment 4, we determined the signal-to-noise ratio (S/N) such that, on average, younger and older adults were able to correctly hear the same percentage of words when words were presented one at a time in noise. In Experiment 5, younger adults were tested under this S/N. Compared with older adults from Experiment 3, younger adults in this experiment recalled more words at all serial positions. The results are interpreted as showing that encoding in secondary memory is impaired by aging and noise either as a function of degraded sensory representations, or as a function of reduced processing resources. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Time of peak drug concentration after a single dose and a dose at steady state

The time of peak concentration after administration of oral drug is an often quoted and used pharmacokinetic parameter. It is not well appreciated, however, that the peak times after a single dose and a dose at steady state during a multiple administration regimen can differ significantly. This article derives the mathematical relationships that determine how a peak time at steady state differs from that after a single or first dose. These relationships are then evaluated using three different approaches: 1) graphic simulations of time courses of drug concentration for three hypothetical drugs; 2) comparisons of predicted and observed peak times using examples from the literature; and 3) comparisons of predicted and simulated peak times based on different sampling schedules for three hypothetical drugs. The key finding is that peak times after a dose at steady state can occur considerably earlier after administration than after a single dose. However, the manner by which peak times are usually determined, that is, the sampling time corresponding to the highest measured drug concentration, imposes significant limitations on the usefulness of this parameter.     

Hemodynamic effects of thiothixene and chlorpromazine in schizophrenic patients at rest and during exercise

The hemodynamic effects and plasma levels of noradrenaline were studied in schizophrenic patients at rest and during exercise after long-term treatment with chlorpromazine (150-600 mg daily) and thiothixene (60-80 mg daily). The results are compared with those from previous studies in untreated patients and patients receiving very large doses of chlorpromazine. The effects of thiothixene on the different hemodynamic variables were very moderate, and the observed differences between this group and the control group may be due to the different patient materials. In the two groups of patients receiving chlorpromazine, the heart rate at rest and durng exercise tended to be higher than in the control group. There was also a tendency towards a lower stroke volume after this drug and thiothixene during exercise. The noradrenaline levels in plasma were highest after the high dose of chlorpromazine both at rest and during exercise, while they were lower after the moderate chlorpromazine dose. After thiothixene, the values were between those of the group on the low chlorpromazine dose and those of the control group.     

The pharmacokinetics and steady state pharmacodynamics of mivacurium in children

BACKGROUND: The main causes of allograft failure after cardiac transplantation are primary graft dysfunction, intractable acute rejection, and coronary graft disease. Despite the important progress in the last several years in graft preservation, surgical techniques, immunosuppression, and treatment of coronary graft disease, retransplantation in selected cases is the only way to achieve long-term recipient survival. METHODS: We compare here in a case-control study 24 retransplantations with 47 first transplants in patients matched for date of transplantation. RESULTS: Between 1973 and 1996, 1,063 patients underwent cardiac transplantation in our institution. In this cohort, 22 patients had a total of 24 retransplantations (2 second-time retransplantations). The causes of retransplantations were primary graft failure (n=4), acute rejection (n=7), coronary graft disease (n=11), and miscellaneous (n=2). Survival at 1 and 5 years of patients with retransplantations is 45.5% and 31.2%, and survival of control patients is 59.4% and 38.8% (p=0.07). An interval between first transplantation and retransplantation shorter (n=11) or longer (n=13) than 1 year is associated with a 1-year survival of 27.3% and 61.5% and a 4-year survival of 27.3% and 46%, respectively (not significant). Intervals shorter than 1 year between first transplantation and retransplantation were exclusively secondary to primary graft failure or intractable acute rejection. CONCLUSIONS: In the face of lack of donor grafts, these and other data indicate that retransplantation should be considered cautiously, especially when the interval between the first transplantation and retransplantation is short.     

Comparison of plasma and saliva concentrations of the active monohydroxy metabolite of oxcarbazepine in patients at steady state

A study was performed in ten patients, stabilized with oxcarbazepine monotherapy (450-750 mg bid) for two weeks minimum, to investigate the possibility of using saliva to monitor the oxcarbazepine therapy. Thirteen paired blood and saliva samples were taken over 24 h. The saliva samples were obtained after stimulation. The analysis performed on the data suggests a dose dependence for the relationship between plasma and saliva concentrations of the main active metabolite, 10, 11-dihydro-10-hydroxycarbamazepine (MHD), and the importance of the type of stimulation for the saliva's production. Therefore it would be preferable to use plasma concentrations to monitor oxcarbazepine therapy, if necessary.     

Marked intra- and inter-patient variability of itraconazole steady state plasma concentrations

Prospective clinical studies about photocoagulation of extrafoveolar choroidal neovascularizations in focal hemorrhagic chorioretinopathy (CR) have demonstrated that the risk of visual loss years after successful treatment is related to the development of retinal pigment epithelium (RPE) atrophy around the laser scar. The reason for this event was thought to be late damage of RPE cells due to the laser treatment. However, because RPE atrophy can also be seen in untreated patients, a prospective study was started to test this pathogenetic hypothesis and to analyze the pathogenetic factors and prognostic importance of RPE atrophy in focal hemorrhagic CR. Eighty-eight patients (52 women, 36 men, 15-45 years old; mean follow-up 62 months; 26 patients treated by photocoagulation) with focal hemorrhagic CR were reexamined. Fifty-two patients (15 treated by photocoagulation and 37 untreated) showed clinically visible RPE atrophy. In these 52 patients the initial and final visual acuity, the amount of initial subretinal fluid (34.6% < 500 microns, 50% 500-750 microns, 15.4% > 750 microns) and the amount RPE atrophy (23.2% < 500 microns, 53.6% 500-750 microns, 23.2% > 750 microns) were analyzed. The development of RPE atrophy was dependent on the time of follow-up (36 patients without RPE atrophy, mean follow-up 29 months; 52 patients with RPE atrophy, mean 84 months, P < 0.001). Of the 52 patients with RPE atrophy, 15 were treated by photocoagulation. The distribution of RPE atrophy was similar to what was found in the 37 untreated patients (P = 0.4). With pronounced RPE atrophy, a decrease in final visual acuity was seen (RPE atrophy < 500 microns, mean visual acuity 0.5; 500-750 microns mean visual acuity 0.3; > 750 microns, mean visual acuity 0.1; P = 0.005). Increased RPE atrophy was also associated with a higher incidence of visual loss (p = 0.009). The amount of RPE atrophy was not dependent on the time of follow-up (P = 0.3), but only correlated with the initial amount of subretinal fluid (atrophy < 500 microns: subretinal fluid < 500 microns 15.4%, 500-750 microns 7.7%, > 750 microns 0%; atrophy 500-750 microns: subretinal fluid < 500 microns 19.2%, 500-750 microns 32.7%, < 750 microns 1.9%; atrophy > 750 microns: subretinal fluid < 500 microns 0%, 500-750 microns 9.6%, > 750 microns 13.5%; P < 0.0001). Because RPE atrophy in focal hemorrhagic CR was seen in patients both with and without photocoagulation therapy, laser treatment cannot be the causative factor. With increased follow-up the risk of the development of RPE atrophy increases in all patients. The resulting amount of RPE atrophy was only dependent on the initial amount of subretinal fluid. If the fovea is included in the exudative detachment, there is a higher risk of long-term visual loss.     

A new look at the effects of noise: A rejoinder.

Outlines a composite theory to account for the effects of noise upon performance. The 4 main determinants are (a) masking, both of acoustic cues and of inner speech; (b) distraction; (c) a beneficial increase in arousal when the noise begins, which gradually lessens and falls below normal to produce a decrement in performance when the noise stops; and (d) positive and negative transfer from noise to quiet. Positive transfer results from the more effective learning of the task in noise under the influence of the increase in arousal. Negative transfer results from the techniques of performance used in noise to counteract the masking or distraction, when they are not appropriate in quiet. (49 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dynamic recovery during and after steady state deformation of Al-11wt%Zn

Cylindrical specimens of Al-11wt%Zn were deformed at constant stress and at 523 K in tensile creep tests. The stress dependence of the steady state deformation rate ge_s, was determined from stress change tests, ge_s shows an exponential stress dependence in the stress range above 10 MPa. The steady state values of the dislocation density in the subgrain interior (ρ_i) and of the subgrain size were determined by means of transmission electron microscopy. The fundamental equation of steady state deformation ge_s = (bM)Agr⁻ was tested by independent measurement of ge_s and gr⁻. A is of the order of the subgrain size. gr⁻ was determined from the recovery behavior of the dislocation density immediately after steady state deformation. The shape of the recovery curves did not depend on type and amount of stress reduction but was strongly dependent on ge_s. These results were confirmed by measurements of the transient creep behavior after reloading the specimens with the initial load. For the exact determination of gr⁻ an interpolation method was used, which is based on the decrease ofρ_i during stress relaxation. The shape of the recovery curves and the stress dependence of ge_s.A and gr⁻ suggest that recovery during and immediately after steady state deformation is of dynamic nature.     

Hemodynamic effects of amlodipine and benazeprilat in spontaneously hypertensive rats

We wished to assess the hemodynamic effects of administration of the combination of the calcium channel blocking agent amlodipine and the angiotensin-converting enzyme (ACE) inhibitor benazeprilat in conscious spontaneously hypertensive rats (SHR). In SHR previously instrumented for measurement of mean arterial blood pressure (MAP) and heart rate (HR), intravenous (i.v.) injection of amlodipine (0.25-4 mg/kg) produced dose-dependent decreases in blood pressure (BP). Administration of benazeprilat (0.1-10 mg/kg i.v.) decreased arterial MAP, and benazeprilat (10 mg/kg) effectively blocked the effects of exogenously administered angiotensin I (AI). In animals surgically prepared for measurement of BP, HR, and hindquarter, renal, and mesenteric blood flows, administration (i.v.) of the combination of amlodipine (0.5 mg/kg) with benazeprilat (10 mg/kg) evoked a decrease in BP that was greater than that elicited by monotherapy. The tachycardic response observed after administration of the combination was no different from that observed after monotherapy with amlodipine. Simultaneous administration of amlodipine and benazeprilat produced reductions in vascular resistance in the hindquarter, renal and mesenteric beds that were greater than the responses evoked by injection of either agent. The major finding of these studies was that dual therapy with amlodipine and benazeprilat produced an additive hypotensive effect in conscious SHR. Regional vasodilation accompanied the large degree of hypotension evoked by the combination.     

Approximations of open quotient and speed quotient from glottal airflow and EGG waveforms: effects of measurement criteria and sound pressure level

A sample of speech acts in everyday discourse referring to persons or events having to do with the term mental retardation was analyzed in order to investigate the belief that language use both constructs and reflects cultural norms that define the social roles of persons reduced to object status through categorical membership. Speech acts gathered suggest four emergent themes: the discourse of category membership, the dichotomy of normal and abnormal, issues of place and space, and fear. These themes were explicated from a social constructionist perspective, displaying the way speech acts construct mental retardation and subvert individuals with the label into demeaned and ridiculed objects of cultural fear.