THE PETROLOGY OF THE MIDDLE JURASSIC SANDSTONES FROM THE MURCHISON FIELD, NORTH SEA

A petrographical investigation of the sandstones of the Brent Group (Middle Jurassic) from the Murchison field has produced evidence for the existence of two transgressive events within the sequence, one occurring immediately above the Etive Fm., the other within the upper part of the Ness Fm. These transgressions have not been previously recorded in Murchison and their discovery demands that some modification be made to the existing depositional model for the Brent Group of this area. A volcanic ash horizon has been found in a similar stratigraphic position to that recorded from Statfjord, and if this, and the two transgressive horizons noted above, are of more than local extent they could prove to be useful stratigraphic markers.
Although the diagenesis of the Brent Group sandstones in Murchison differs little from that recorded elsewhere in the Brent province, the interpretation of the timing of the development of certain phases differs somewhat from those of other authors. In particular, kaolinite development appears to have taken place soon after burial in response to periods of emergence and weathering during Brent Group deposition, rather than through groundwater circulation during the Kimmerian tectonic phase.     

The effect of an infusion of low molecular weight dextran on peripheral resistance in patients with arteriosclerosis

Low molecular weight dextran is frequently given to improve the flow of blood to the periphery, but its mode of action is uncertain. We measured the effect of an infusion of 500 ml of Dextran 40 on the peripheral resistance in 12 patients undergoing reconstructive surgery for atherosclerotic occlusion of the superficial femoral artery. After the infusion, values of packed cell volume and blood viscosity indicated haemodilution. There was a consistent increase in mean flow and a fall in peripheral resistance. There was no correlation between change in viscosity and change in peripheral resistance, but there was a good correlation between the percentage change in resistance and the initial resistance. This suggests that the increase in flow of blood was due to reflex vasodilatation rather than to any reduction in viscosity.     

A context noise model of episodic word recognition.

Item noise models of recognition assert that interference at retrieval is generated by the words from the study list. Context noise models of recognition assert that interference at retrieval is generated by the contexts in which the test word has appeared. The authors introduce the bind cue decide model of episodic memory, a Bayesian context noise model, and demonstrate how it can account for data from the item noise and dual-processing approaches to recognition memory. From the item noise perspective, list strength and list length effects, the mirror effect for word frequency and concreteness, and the effects of the similarity of other words in a list are considered. From the dual-processing perspective, process dissociation data on the effects of length. temporal separation of lists, strength, and diagnosticity of context are examined. The authors conclude that the context noise approach to recognition is a viable alternative to existing approaches. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of dynamic recrystallization on the importance of grain-boundary sliding during creep

During creep of polycrystalline materials at elevated temperatures, a certain amount of the strain is accommodated by grain-boundary sliding (GBS). The relative importance of GBS depends on the stress and grain size and sometimes temperature. During high-strain deformation, dynamic recrystallization often occurs with the resultant grain size only related to the stress. In this situation the importance of GBS is then dependent only upon stress and sometimes temperature. In dynamically recrystallized Magnox Al80 deformed atT>0.8T _m, 16 to 23% of the imposed strain is accommodated by GBS. A comparison has been made between the experimental results and some theoretical models for the importance of GBS during creep, modified to take account of recrystallization. The best fit to the data is obtained with the modified form of Langdons model. Deformation mechanism maps constructed with this model suggest that dynamic recrystallization can cause a switch of mechanism from dislocation creep to dominant GBS at intermediate temperature (T<673 K) and low stress. Deformation mechanism maps have also been constructed for calcite based on the data of Schmidet al. These suggest that GBS is an important mechanism in calcite deformed under geological conditions.     

Generation currents, noise and auger suppression in intrinsic diodes

The total diffusion-limited current and shot noise in intrinsic diodes do not depend explicitly on the detailed forms of the individual generation processes, but only on the current and noise of each process acting in isolation. Auger-like processes are relatively suppressed in high reverse bias.     

Testing of total hip replacements: endurance tests and stress measurements. Part 2: Stress measurements

Brittle lacquer techniques and electric resistance strain gauge rosettes were used to measure strains on the stems of total hip replacements while loaded according to three standards. The stresses in these locations were also calculated and good agreement was found between the measured and calculated values. The Sines equation was used to calculate the endurance limit stress. Again good agreement was found with observed results. Suggestions are made regarding the endurance testing of hip prostheses.     

Monoamine synaptic structure and localization in the central nervous system

The monoamines dopamine, noradrenaline, adrenaline, and serotonin as well as the diamine histamine have a widespread distribution in the central nervous system within synaptic terminals and nonsynaptic varicosities. In certain regions of the central nervous system the monoamines are contained in varicosities that have no synaptic specialization associated with them, suggesting a possible neuromodulatory role for some of the monoamines. The majority of monoamine labelled structures are synaptic terminals which are characterized by the presence of small, clear vesicles (40–60 nm) and large, granular vesicles (70–120 nm) within the terminal. A third population of vesicles—small, granular vesicles—which are visible only after histochemical staining, are probably the equivalent of the small, clear vesicles present after either autoradiographic or immunohistochemical labelling. Most monoamine containing terminals contact dendrites and dendritic spines and, less frequently, neuronal somata and other axons. Both asymmetrical and symmetrical membrane specializations are associated with monoaminergic terminals; however, asymmetrical contacts are the most frequent type found. These ultrastructural results indicate that monoamine containing terminals and varicosities in general share many common morphological features, but still have diverse functions.     

Object-based inhibition of return in patients with posterior parietal damage.

Recent evidence has shown that inhibition of return, IOR, is impaired in patients with parietal damage with or without clinical signs of neglect (Bartolomeo, Sieroff, Decaix, & Chokron, 2001; Vivas, Humphreys, & Fuentes, 2003, respectively). In addition to environment-based IOR, Tipper et al. (1991) showed that IOR could be also associated with dynamic, object-based representations. In our study, we examined four patients with unilateral lesions to the parietal lobe, and a group of healthy controls, in an IOR procedure with moving objects where a pre-cued object could move, clockwise or counterclockwise, 90° in polar coordinates. The group of control participants showed a small but significant object-based IOR effect. In contrast, the patients showed an object-based IOR effect when the objects moved from the contralesional field toward the ipsilesional field, whereas there was no IOR effect when they moved from the ipsilesional to the contralesional field. These findings are discussed in terms of the role of the parietal cortex in implementing attentional biases in both environment-based (Vivas et al., 2003) and object-based frames of reference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)