Ocean wave power

The wave energy arriving on the west coast of the United Kingdom represents a very substantial energy resource, amounting on average to more than twice the present installed capacity of the Central Electricity Generating Board. Recent comprehensive studies by the CEGB^1,2 and the National Engineering Laboratory³ suggest that although there is no obvious technical reason for being unable ultimately to harness much of this energy, and many methods have been proposed, there are still considerable uncertainties over the choice of wave power system and its economics. Wave power does show sufficient promise however to have been made the subject of serious studies supported by the CEGB and the Department of Energy.⁴In this paper the potential of wave power and some of the more promising methods of harnessing it are discussed, together with an appreciation of some of the many technical and engineering problems which still need to be examined, and a discussion of the impact of wave power on the environment. By considering the results of recent research and their impact on wave power economics it is argued that wave power could be exploited to conserve fossil fuels, but is unlikely to be competitive with nuclear power.     

Dose equivalence and bronchoprotective effects of salmeterol and salbutamol in asthma

BACKGROUND: Salbutamol is the most widely prescribed short acting beta 2 agonist and salmeterol is the first long acting inhaled beta 2 agonist. The dose equivalence of salmeterol and salbutamol is disputed. Estimates of weight-for-weight dose ratio have ranged from 1:2 to 1:16. A study was undertaken to clarify the true dose ratio. METHODS: The bronchoprotection afforded against repeated methacholine challenge by inhaled salmeterol 25 micrograms and 100 micrograms and salbutamol 100 micrograms and 400 micrograms was compared in a randomised, double blind, placebo controlled, crossover trial. Subjects were 16 stable asthmatics with a baseline forced expiratory volume in one second (FEV1) of > or = 65% predicted, screening concentration provoking a fall in FEV1 of 20% (PC20FEV1) of < or = 8mg/ml, and a shift in PC20FEV1 of more than two doubling concentration steps following inhalation of salbutamol 400 micrograms. On five separate occasions subjects underwent methacholine challenge before and 30 and 120 minutes after drug administration. PD20FEV1 was calculated for each challenge. FEV1 at 90 minutes after drug administration was also recorded. RESULTS: Bronchoprotection afforded by salmeterol was increased at 120 minutes compared with 30 minutes and protection by salbutamol was decreased. Protection by both doses of salmeterol was similar to salbutamol 100 micrograms at 30 minutes but significantly greater at 120 minutes. FEV1 at 90 minutes was significantly greater after salmeterol 100 micrograms than after placebo, but there were no other significant differences between treatments. Maximal observed protection was equivalent for salmeterol 100 micrograms and salbutamol 400 micrograms. CONCLUSIONS: The data are compatible with a weight-for-weight dose ratio for salmeterol:salbutamol of < or = 1:4.     

Role of acoustic striae in hearing: discrimination of sound-source elevation

After years of systematic experimentation, we finally uncovered one thing the dorsal system contributes to hearing which the ventral system may not -- the mechanism for orienting to an elevated sound source [Sutherland, D.P., Masterton, R.B., Glendenning, K.K. (1998) Behav. Brain Res. in press]. This paper follows up this one positive result on a historical background of uniformly negative results. The focus of this report is on the fusiform cells of the dorsal cochlear nucleus whose axons course through the dorsal acoustic stria (DAS). Because electrophysiological studies have shown that the cues for sensing the elevation of a sound source would seem to be best analyzed by the dorsal cochlear nucleus, we tested, behaviorally, normal cats and cats deprived of their DAS or intermediate acoustic stria, bilaterally or ipsilaterally (with or without their contralateral ear deafened), for their ability to orient to elevated sources of broad-band noise. For behavioral testing, we made use of a conventional shock-avoidance procedure. The results lead to the conclusion that DCN and DAS may play no role in learned elevation discriminations. This result builds on that of another of our papers which suggests that a deficit in reflexive discrimination of elevation is strictly auditory in nature [Sutherland, D.P., Masterton, R.B., Glendenning, K.K. (1998) Behav. Brain Res. in press].     

Behavior of cats with lesions of the septal forebrain or anterior sigmoid neocortex.

Tested 22 spayed female cats preoperatively on a BLACK-WHITE discrimination, placing responses, visual-cliff preferences, and open-field activity. Subsequently, Ss received lesions in the septum or anterior sigmoid gyrus or remained as normal controls. Postoperatively, Ss were retested on all preoperative tasks and also on passive-avoidance, serial reversal, delayed-alternation, and searching tasks. The anterior sigmoid group was impaired in relearning a BLACK-WHITE discrimination. Both the frontal and septal groups were more active than controls in the open field and also were impaired on the last 100 trials of delayed alternation. No differences were observed among the groups in the remainder of the tasks. (46 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Microstructural Development on Crystallizing Hot-Pressed Pellets of Cordierite Melt-derived Glass Containing B2O3 and P2O5

Comparing the crystallization mechanism of stoichiometric and B₂O₃ and P₂O₅ containing glass reveals that the additives extend the gap between the glass transition and crystallization temperatures and suppress formation of μ, cordierite while promoting direct crystallization of α cordierite. Detailed TEM analysis of nucleation and growth of crystals in hot-pressed pellets of B₂O₃/P₂O₅-containing glass particles shows that nucleation occurs on unidentified heterogeneous nuclei at the sites of the previous particle surfaces. Growth of α cordierite with a cellular morphology or μ cordierite with a dendritic morphology is most likely controlled by the glass composition directly ahead of the growth front.     

Effects of training between two unilateral lesions of visual cortex upon ultimate retention of black-white discrimination habits by rats.

Examined the effects of training between 2 successive unilateral posterior neocortical ablations upon retentions of black-white discrimination habits by 158 male Long-Evans rats. Such practice, but not extra practice, given prior to either a single-stage bilateral ablation or prior to the lst of 2 successive unilateral ablations, partially protected the habit from impairment by a later operation. 2nd unilateral posterior, but not anterior ablations, always yielded a further loss of the habit regardless of the level of interoperative performance of the habit. The habit was well retained after having been relearned after having been impaired as a consequence of single-stage bilateral posterior ablations. Results suggest that the visual neocortex normally suppresses the formation of subcortical black-white engrams or routes of access to such engrams. (25 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)