ALBERT

Notes: The distribution of Trachinus vipera, worldwide and around the British coast, is summarised. Field observations indicate that the fish occurs throughout the intertidal zone; is more active at low light intensities, and can survive the low tide period buried in the intertidal sand; can tolerate salinities as low as 19%0, for short periods; exhibits a tidal periodicity, is more active on the flood tide than the ebb tide; moves into deeper warmer water in winter, the extent.of the movement being temperature dependent. The critical temperature initiating this movement is probably 5deg; C. The fish is not available for capture in cold weather, because it may be hibernating, buried in the sand.

Notes: [Auszug] Cellulolytic activity has been recorded previously in several polychaete worms, including Loimia medusa and Sabellastarte indica, whereas reputedly carnivorous forms, such as Glycera chioni, do not seem to possess a cellulase. We have investigated cellulase activity in N. virens by a technique ...

Notes: [Auszug] While engaged on an ecological study of this annelid the opportunity was taken to investigate its breeding. Rasmussen has been quoted by Thorson1 to have expressed the opinion that the reproduction of this species is non-pelagic. A study of the Northumberland population has shown that not only is ...

Notes: Résumé Les réponses du nerf tympanique des Tettigonides sont conformes à la structure actuelle des transmetteurs du chant naturel mais non pas si le chant est reproduit par enregistrement magnétique ordinaire. On a montré que les constituants ultrasoniques sont essentiels et que les réponses parfaites ne sont obtenues que lorsqu'on a pu produire des fréquences très hautes.

Notes: Abstract The songs of six species of bush cricket are shown to have a high-intensity spectral component at low frequencies. These low frequencies may occur as sweeps, and are the expression of the tooth-impact rate; corresponding pulses are seen in high-frequency sonagrams. It is suggested that the intermediate organ is particularly sensitive to this frequency representing the tooth impacts. Hence, as a possibly important segment of the total message, this low-frequency information must be properly conserved, particularly in playback from high-speed tape recordings, which tend to cut it out. In this context, the relevance of recent work on receptors to the problem of carrier-frequency discrimination is reviewed, and it is argued that this is normally by an averaging process analogous to that of human colour vision, as first suggested by Pumphrey (1940).

Notes: Summary Analyses of natural songs from the cricketTeleogryllus oceanicus confirm (after Hutchings and Lewis 1984) that the songs are rich in harmonics which extend up to around 55 kHz. A series of synthetic song models with a varying harmonic content were used to determine the relevance of these harmonics to the orientation behaviour of the insects. In two-choice experiments in which song models were presented simultaneously, crickets showed a clear discrimination between a song with harmonics and a song without. Female insects orientated preferentially to a song with harmonics. Interestingly, males preferred a song model without harmonics in the two-choice situation. Two experimental regimes were used to test orientation accuracy, a forced-choice (Y maze) phonotactic experiment and a study of free phonotaxis in the behavioural arena. The results of both experimental approaches confirm that crickets orientate more accurately to a song with harmonics and can discriminate smaller angles to sound sources ahead and lateral to the insect. Presentations of song models in which the fundamental (5 kHz) was attenuated relative to the 2nd harmonic have given results that imply a process of neural integration (two-tone or side band suppression) of the fundamental and the high-frequency harmonics.

Notes: Summary 1. Response/intensity curves for the 50 ms periods following the onset of stimulation are given, for the anterior membrane ofPlatycleis intermedia, in Fig. 2A and for the posterior membrane ofHomorocoryphus nitidulus vicinus in Fig. 2B. These curves are frequency-dependent, varying in threshold intensity, intensity band and maximum amplitude criteria. 2. Similar curves are given for the 50 ms following the termination of the stimulus, in Fig. 3A-B. Attention is drawn to the significance of these ‘off’ responses. 3. The response/intensity curves are critically analysed by three different methods; for threshold; for a constant intensity level (CI); and for a constant response level (CR). The differences in the values obtained by these methods are shown in Fig. 4A-H. 4. The CR (sensitivity) curves for the anterior membrane ‘on’ response ofP. intermedia are given in Fig. 5 and for the ‘off’ response in Fig. 6. The threshold curves show the typical ‘narrow-band’ spectrum, with peak sensitivity at the main carrier frequency of the song, and smaller peaks at 0.8 kHz and 30 kHz. At higher response amplitudes however, these peaks disappear, or are greatly diminished relative to other frequencies except for the low-frequency ‘off’ response. 5. The CI (efficiency) curves for the anterior membrane ‘on’ response are shown for seven intensity values in Fig. 7. Increasing the intensity of stimulation emphasizes the broadband nature of the receptor and demonstrates an important high-frequency peak (70 kHz), not apparent at lower intensities. The ‘off’ responses (Fig. 8) show similar effects. 6. For the posterior membrane, curves were drawn of the maximum response, and of the stimulus required to give the maximum response, against frequency. These are given for the ‘on’ response (Fig. 9) and for the ‘off’ response (Fig. 10). The posterior membrane is insensitive to the termination of the stimulus. 7. No responses were obtained from the central membrane for frequencies between 200 Hz and 250 kHz. 8. The response activity during each 5 ms period of the stimulus and stimulus interval is shown for the anterior and posterior membranes in Figs. 11, 12. This steady-state activity is membrane- and frequency-dependent, and clearly demonstrates the nature of the ‘off’ responses. 9. The effects of varying the stimulus duration and the stimulus-interval duration, on the amplitudes of response and latencies of response, are shown in Figs. 13A and B. Consideration of these figures indicates that neither the ‘on’ nor ‘off’ responses are due to any inhibitory release or ‘rebound’ phenomena. 10. The effect of environmental attenuation of sound frequencies (0.8 kHz-20 kHz) (Fig. 14) on the song spectrum (Fig. 15) suggests that distance is perceived as a variation in the intensity-response at low frequencies. 11. The excess sound pressure at the spiracle, due to the diffraction of sound by the body surface, as a function of the angle of incidence (Fig. 16A-B), shows that directionality becomes possible only at frequencies above 7 kHz. The effect of this excess pressure on the song spectrum is demonstrated (Fig. 17) and suggests that directionality is a feature of higher frequencies, and can be coded as an intensity function. 12. When the pronotal shield is removed, this high-frequency directionality is eliminated (Fig. 16B). Thus, the pronotum is important for the effectiveness of the sound stimulus entering the spiracle. 13. The implications of these results for the mode of functioning of the ear and for acoustic behaviour are discussed. The way is now clear for the critical determination of the role of the acoustic trachea.

Notes: Abstract Pure titanium and Ti-6Al-4V were exposed at 750°C in an H2/H2O/H2S PO 2≈10−18 Pa and PS 2≈10−1 Pa), H2/H2O (PO 2≈10−18 Pa) and air environments for up to 240 hr. The corrosion kinetics, obtained by the discontinuous gravimetric method, showed that the sulfidation/oxidation kinetics were linear for Ti and linear-parabolic for Ti-6Al-4V in the H2/H2O/H2S environment. Both materials obeyed parabolic rate laws in the H2/H2O atmosphere after a transient period, and linear-parabolic rate laws in air. After exposure to the H2/H2O/H2S atmosphere, the titanium specimen displayed a double scale of TiO2 with an intervening TiS2 film between the double-layered scale of TiO2 and the substrate. Ti-6Al-4V also contained a double layer of TiO2 together with a stratum consisting of Al2S3, TiS2 and vanadium sulfide at the junction of the inner TiO2 layer and substrate. Some Al2O3 precipitated in the external portion of the outer TiO2 layer. Following oxidation in the low-PO 2 atmosphere a double-layered oxide of TiO2 scale formed on both Ti and Ti-6Al-4V. The scale on Ti-6Al-4V also contained an α-Al2O3 film situated between the outer and inner (TiO2) layers. For both materials, multilayered-scale formation characterized air oxidation. In detail a multilayered oxide scale of TiO2 formed on the air-oxidized Ti, while a multilayered oxide scale with alternating layers of Al2O3/TiO2 developed on Ti-6Al-4V oxidized in air.

Notes: Abstract Multilayer coatings have been produced using unbalanced magnetron physical vapour deposition in which discrete layers of TiN and ZrN were co-deposited. It has been shown that the multilayers exhibited two-fold periodicity having values of 13 and 2.8 nm. This periodicity, measured both by cross-sectional transmission electron microscopy and low-angle X-ray diffraction, has been precisely related to the process parameters used. Analysis has shown that a third, previously unreported, phase existed within the coating having a lattice parameter comparable to that of TiN and a well-defined orientation relationship with the primary phases. The existence of this phase has been explained in terms of variations in the stoichometry of the coating due to non-uniform metal to nitrogen deposition rates within the chamber. Textural studies revealed that preferred orientation existed in the coating; the degree of which was greater in the ZrN layers than the TiN layers.