The complex characteristics of crystallization of the Fe75Si15B10 glassy ribbon

The Fe₇₅Si₁₅B₁₀ glassy ribbon was examined in the course of various isothermal and dynamic heat treatments. The number, type and mechanism of formation of the crystallization products formed during two crystallization stages in this alloy were determined by differential scanning calorimetry (DSC), thermomagnetometry, transmission electron microscopy and X-ray diffraction measurements. It is concluded that the first DSC peak is due to the crystallization of α-Fe(Si) or Fe₃Si and the composite microcrystals containing Fe₃B cores with α-Fe(Si) envelopes. The metastable Fe₃B subsequently transforms into the stable Fe₂B in the second DSC peak. The remaining amorphous matrix crystallizes by the eutectic reaction also in the second DSC peak forming the Fe₃Si and Fe₂B eutectic structures. The apparent activation energy E ₁ ^⊛ decreases during the first crystallization stage from 480 kJ (g atom^-1), characteristic of the Johnson–Mehl–Avrami (JMA) nucleation-and-growth kinetics of the as-quenched sample, to 350 kJ (g atom)^-1 implying a dominance of the diffusion-controlled growth of iron in the already pre-nucleated sample. Simultaneously, the JMA exponent n ₁ decreases from 2.5 to 1.5. The apparent activation energy E ₂ ^⊛ depends on the temperature of the first crystallization stage. It decreases with increasing T _a from 384 to 282 kJ (g atom)^-1. This phenomenon was attributed to modification of the chemical composition of the remaining eutectic after the temperature dependent primary crystallization of Fe₃B within the composites. The value of n ₂ is 3. This revised version was published online in November 2006 with corrections to the Cover Date.     

A driving-simulator test of Wilde's risk homeostasis theory.

Previous experimental tests of risk homeostasis theory (RHT) have failed to manipulate both motivational and nonmotivational variables in an ecologically valid within-subject design. In this study, 24 Ss operated an interactive driving simulator under varying levels of a within-subject motivational factor (monetary accident cost), a within-subject nonmotivational factor (speed limit), and a between-subjects nonmotivational factor (speeding fine). Consistent with RHT, increased speed limit and reduced speeding fine significantly increased driving speed but had no effect on accident frequency. Moreover, increased accident cost caused large and significant reductions in accident frequency but no change in speed choice. Results suggest that in contrast to motivationally based accident countermeasures, regulation of specific risky behaviors such as speed choice may have little influence on accident rates. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of Tempering on the Texture and Polymorphic Behaviour of Margarine Fats

Separated fats from commercial soft (soft fat) and stick (stick fat) margarines and mixtures of hydrogenated super olein (H-olein) and canola oil, were temperature cycled between 4°C and 15,20 and 25°C. The polymorphic form, SFC and texture of the fats were evaluated. Temperature cycling of soft fats between 4 and 20°C resulted in the crystals being either in the β polymorphic form or mixtures of β′ and β. When temperature cycled between 4 and 15°C the presence of β′ crystals was improved, but there were soft fats that after the fourth cycle contained only β crystals. When stick fats were temperature cycled between 4 and 20°C, the crystals after the fourth cycle were either in the β′ form or contained mixtures of β′ and β. Mixtures of H-olein-canola showed superior β′ stability throughout. A mixture of 20% H-olein/canola oil compared well with the SFC and texture of soft margarines while a mixture of 40% H-olein/canola oil with those of stick margarines. Texture was evaluated by constant speed penetration. Texture of fats is very dependent on temperature history. DSC-crystallization curves of the fats showed a variety of patterns.     

Anesthetic management in epidermolysis bullosa: review of 129 anesthetic episodes in 32 patients

Non-adrenergic non-cholinergic (NANC) inhibitory nerves have been described in all regions of the gastrointestinal tract, but have not been shown previously in the human gall bladder. Electrical field stimulation was used in the presence of various agonists and antagonists to show NANC inhibitory innervation in strips of human gall bladder muscle. Gall bladder strips were set up isometrically in an organ bath containing oxygenated Krebs's solution. Electrical field stimulation was applied at 10 Hz, pulse width 0.3 ms and supramaximal voltage at intervals of 3 to 5 minutes. Of 60 strips that contracted in response to electrical field stimulation, 30 showed relaxation on electrical field stimulation in the presence of either carbachol (5-10 microM) or else atropine (0.5-2 microM) plus cholecystokinin octapeptide (0.01-0.1 microM) or caerulein (0.1 nM) or histamine (5-10 microM). In 22 strips this relaxation was not abolished by guanethidine (2-5 microM) showing the NANC nature of this response. The NANC relaxation was abolished by L-nitroarginine (100 microM) and this effect was partly reversible by L arginine (200 microM). All responses to electrical field stimulation were abolished by tetrodotoxin (0.2-2 microM). These results show for the first time a NANC inhibitory innervation in human gall bladder muscle. The probable neurotransmitter is nitric oxide.     

INTENT: a method for estimating human error probabilities for decisionbased errors

The development of a method, INTENT, for estimating probabilities associated with decisionbased errors is presented. These errors are not ordinarily incorporated into probabilistic risk assessments (PRAs) due to both the difficulty in postulating such errors and to the lack of a method for estimating their probabilities from existing data. By failing to include decisionbased errors in their analyses, most PRA practitioners seriously underestimate the true contribution of human actions to systems failure. This paper attempts to extend the identification of such errors and to quantify them. Two sources, Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) and licensee event reports (LERs) were reviewed and two methods, HSYS and SNEAK, were used to identify a generic list of twenty potential errors which may be manifest as erroneous acts. Four categories of influence emerged from the data: consequence, attitudes, response set, and dependency. Corresponding human error probabilities (HEPs) for each error were generated by expert judgment methods. Lower and upper bounds for the HEPs for each error were determined by positing a situation reflecting optimized and degraded performance shaping factors, respectively. To allow analysts the opportunity to refine these extreme HEP values when evaluating a particular scenario of interest, normalization procedures were conducted and generic importance weights were computed for each of 11 performance shaping factors (PSFs) believed to affect the 20 decisionbased errors. It is believed by the authors that PSFs constitute a performance influence which, in some cases, such as in that for training, can serve to either augment or reduce the intellectual resources used by people to successfully accomplish tasks. These derived importance weights are used in conjunction with situation specific PSF ratings to compute a composite PSF score which, in turn, is mapped onto an HEP distribution. Distribution assumptions are presented and a function defining the relationship between composite PSF scores and HEPs is presented for use by the analyst.