Boyle's Law ignores dynamic processes in governing barotrauma in fish.

The expansion and potential rupture of the swim bladder due to rapid decompression, a major cause of barotrauma injury in fish that pass through turbines and pumps, is generally assumed to be governed by Boyle's Law. In this study, two swim bladder expansion models are presented and tested in silico. One based on the quasi-static Boyle's Law, and a Modified Rayleigh Plesset Model (MRPM), which includes both inertial and pressure functions and was parametrised to be representative of a fish swim bladder. The two models were tested using a range of: (1) simulated and (2) empirically derived pressure profiles. Our results highlight a range of conditions where the Boyle's Law model (BLM) is inappropriate for predicting swim bladder size in response to pressure change and that these conditions occur in situ, indicating that this is an applied and not just theoretical issue. Specifically, these conditions include any one, or any combination, of the following factors: (1) when rate of pressure change is anything but very slow compared to the resonant frequency of the swim bladder; (2) when the nadir pressure is near or at absolute zero; and (3) when a fish experiences liquid tensions (i.e. negative absolute pressures). Under each of these conditions, the MRPM is more appropriate tool for predicting swim bladder size in response to pressure change and hence it is a better model for quantifying barotrauma in fish.

Applying appropriate frequency criteria to advance acoustic behavioural guidance systems for fish.

Deterrents that use acoustics to guide fish away from dangerous areas depend on the elicitation of avoidance in the target species. Acoustic deterrents select the optimum frequency based on an assumption that highest avoidance is likely to occur at the greatest sensitivity. However, such an assumption may be unfounded. Using goldfish (Carassius auratus) as a suitable experimental model, this study tested this as a null hypothesis. Under laboratory conditions, the deterrence thresholds of individual goldfish exposed to 120 ms tones at six frequencies (250-2000 Hz) and four Sound Pressure Levels (SPL 115-145 dB) were quantified. The deterrence threshold defined as the SPL at which 25% of the tested population startled was calculated and compared to the hearing threshold obtained using Auditory Evoked Potential and particle acceleration threshold data. The optimum frequency to elicit a startle response was 250 Hz; different from the published hearing and particle acceleration sensitivities based on audiograms. The difference between the deterrence threshold and published hearing threshold data varied from 47.1 dB at 250 Hz to 76 dB at 600 Hz. This study demonstrates that information obtained from audiograms may poorly predict the most suitable frequencies at which avoidance behaviours are elicited in fish.

Extraterrestrial sound for planetaria: A pedagogical study.

The purpose of this project was to supply an acoustical simulation device to a local planetarium for use in live shows aimed at engaging and inspiring children in science and engineering. The device plays audio simulations of estimates of the sounds produced by natural phenomena to accompany audio-visual presentations and live shows about Venus, Mars, and Titan. Amongst the simulated noise are the sounds of thunder, wind, and cryo-volcanoes. The device can also modify the speech of the presenter (or audience member) in accordance with the underlying physics to reproduce those vocalizations as if they had been produced on the world under discussion. Given that no time series recordings exist of sounds from other worlds, these sounds had to be simulated. The goal was to ensure that the audio simulations were delivered in time for a planetarium's launch show to enable the requested outreach to children. The exercise has also allowed an explanation of the science and engineering behind the creation of the sounds. This has been achieved for young children, and also for older students and undergraduates, who could then debate the limitations of that method.

Modelling acoustic scattering, sound speed, and attenuation in gassy soft marine sediments.

A model for nonlinear gas bubble pulsation in marine sediments is presented. This model is then linearized to determine the resonance frequency and the damping terms for linear radial oscillations. The linear model is then used to predict the effects that such bubble pulsations will have on the sound speed and attenuation of acoustic waves propagating in gassy marine sediment. The results are compared for monodisperse populations against the predictions of a model of Anderson and Hampton and, furthermore, the additional abilities of the model introduced in this paper are discussed. These features include the removal of the sign ambiguities in the expressions, the straightforward implementation for acoustic propagation through polydisperse bubble populations, the capability to estimate bubble size distributions through a full acoustic inversion, and the capability to predict nonlinear effects.

Clutter suppression and classification using twin inverted pulse sonar in ship wakes.

Twin inverted pulse sonar (TWIPS) is here deployed in the wake of a moored rigid inflatable boat (RIB) with propeller turning, and then in the wake of a moving tanker of 4580 dry weight tonnage (the Whitchallenger). This is done first to test its ability to distinguish between scatter from the wake and scatter from the seabed, and second to test its ability to improve detectability of the seabed through the wake, compared to conventional sonar processing techniques. TWIPS does this by distinguishing between linear and nonlinear scatterers and has the further property of distinguishing those nonlinear targets which scatter energy at the even-powered harmonics from those which scatter in the odd-powered harmonics. TWIPS can also, in some manifestations, require no range correction (and therefore does not require the a priori environment knowledge necessary for most remote detection technologies).

A passive acoustic device for real-time monitoring of the efficacy of shockwave lithotripsy treatment.

Extracorporeal shockwave lithotripsy (ESWL) is the preferred modality for the treatment of renal and ureteric stone disease. Currently X-ray or ultrasound B-scan imaging are used to locate the stone and to check that it remains targeted at the focus of the lithotripter during treatment. Neither imaging modality is particularly effective in allowing the efficacy of treatment to be judged during the treatment session. A new device is described that, when placed on the patient's skin, can passively monitor the acoustic signals that propagate through the body after each lithotripter shock, and which can provide useful information on the effectiveness of targeting. These acoustic time histories are analyzed in real time to extract the two main characteristic peak amplitudes (m(1) and m(2)) and the time between these peaks (t(c)). A set of rules based on the acoustic parameters was developed during a clinical study in which a complete set of acoustic and clinical data was obtained for 30 of the 118 subjects recruited. The rules, which complied with earlier computational fluid dynamics (CFD) modeling and in vitro tests, allow each shock to be classified as "effective" or "ineffective." These clinically-derived rules were then applied in a second clinical study in which complete datasets were obtained for 49 of the 85 subjects recruited. This second clinical study demonstrated almost perfect agreement (kappa = 0.94) between the number of successful treatments, defined as >50% fragmentation as determined by X-ray at the follow-up appointment, and a device-derived global treatment score, TS(0), a figure derived from the total number of effective shocks in any treatment. The acoustic system is shown to provide a test of the success of the treatment that has a sensitivity of 91.7% and a specificity of 100%. In addition to the predictive capability, the device provides valuable real-time feedback to the lithotripter operator by indicating the effectiveness of each shock, plus an indication TS(t) of the cumulative effectiveness of the shocks given so far in any treatment, and trends in key parameters. This feedback would allow targeting adjustments to be made during treatment. An example is given of its application to mistargeting because of respiration.

Noise reduction in spine videofluoroscopic images using the undecimated wavelet transform.

Videofluoroscopy permits using sequences of low quality images to study the spine movement. In this work the problem of enhancing the quality of these images is considered in order to facilitate the extraction of kinematic parameters. The method is based on the undecimated wavelet transform and on a preliminary training of a sub-set of images. The anatomical features are preserved using a mask. Key element of the method is its fast and automated implementation. The concept of improving the extraction of kinematic parameters by improving the image representation instead of the technique to extract these is also innovative. The technique has been tested on two sequences of images and the results demonstrates that the method enhances images not related with training sub-set.

Ultrasonic propagation in cancellous bone: a new stratified model.

The theoretical modeling of ultrasonic propagation in cancellous bone is pertinent to improving the ultrasonic diagnosis of osteoporosis. First, this paper reviews applications of Biot's theory to this problem. Next, a new approach is presented, based on an idealization of cancellous bone as a periodic array of bone-marrow layers. Schoenberg's theory is applied to this model to predict wave properties. Bovine bone samples were tested in vitro using pulses centered at 1 MHz over various angles relative to the orientated cancellous structure. Two longitudinal modes (fast and slow waves) were observed for propagation parallel to the structure, but only one was observed for propagation normal to the structure. Angular-dependence of velocities was examined, and the fast wave was found to be strongly anisotropic. These results gave qualitative agreement with predictions of Schoenberg's theory. Although this new model is a simplification of the cancellous architecture, it has potential for future research.

Grain weevil,Sitophilus granarius (L.): Antennal and behavioral responses to male-produced volatiles.

Coupled GC-EAG techniques have been applied to the study of volatiles from the grain weevil,Sitophilus granarius. for the first time. The size of EAG response was independent of the sex of the responding insect but was consistently larger to extracts of males than those of females. This difference was reflected in a behavioral preference for the male extracts by mated adults of both sexes tested together and virgin adults of both sexes tested separately. The GC-EAG results provide evidence for two materials that are released specifically by the males. Using circular dichroism. one has been found to be identical stereochemically with the (2S,3R)-sitophilate reported by others as the aggregation pheromone in a different strain. This enhances the prospects for the development of a single pheromone lure that would be generally applicable whatever the origin of the strain. The small amount of sitophilate found in the males suggests that it is not stored in large amounts. The other material, present in such a small amount that it has yet to be fully characterized, elicits a higher antennal activity than sitophilate and may have a significant role to play in enhancing the trap catch of this economically important pest.

Fluoroscopy-assisted plantar fasciotomy and calcaneal exostectomy: a retrospective study and comparison of surgical techniques.

A retrospective analysis of fluoroscopy-assisted plantar fasciotomy/calcaneal exostectomy is presented. The study included 34 patients whose symptoms were all improved to some degree by the procedure. On a five-point scale, the average improvement of preoperative symptoms was 3.2. There were a total of eight complications. The time it took to return to normal activities and until the pain became less than preoperatively was found to be decreased when compared with traditional methods. This technique, using a single, plantar medial, small incision should be considered as an option in the treatment of recalcitrant plantar fasciitis/heel spur syndrome.

Stereospecific antennal response by red turpentine beetle,Dendroctonus valens to chiral monoterpenes from ponderosa pine resin.

The antennal response ofDendroctonus valens to host monoterpenes from the resin of ponderosa pine was studied using the electroantennogram (EAG) technique. Male and female beetles were given a single dose of each of 11 different monoterpenes. Response amplitude to the different compounds did not vary between sexes and was generally well correlated with results from field attraction studies. Response to (S)-(-)-ß-pinene was greatest. The relative amplitude of the responses to the (R)-(+) and (S)-(-) enantiomers of a-pinene, however, were reversed from their relative attractiveness in the field. A dose-response study was conducted for the (R)-(+) and (S) -(-) enantiomers of a-pinene, plus a reciprocal differential saturation test with successive doses of first one enantiomer ofα-pinene and then the other. Comparison of EAG traces suggests different receptors for the two stereoisomers ofα-pinene. Differential saturation curves suggest that while one set of receptors may respond to both enantiomers, some receptors respond only to the (S)-(-) enantiomer.

Chiral specificity in responses by the bark beetleDendroctonus valens to host kairomones.

The attraction of the red turpentine beetle,Dendroctonus valens, to the resin volatiles of its host,Pinus ponderosa, is elicited by three chiral monoterpenes. In field assays response was greatest to (S)-(-)-ß-pinene; 92% (S)-(-)-α-pinene found inP ponderosa resin was not attractive. However, 75% (R)-(+)-α-pinene, which occurs inPinus lambertiana, a sympatric host ofD. valens, was attractive. (S)-(-)-α-Pinene interrupted response to (R)-(+)-α-pinene. (S)-(+)-3-Carene from both hosts was attractive at the (R)-(+)-α-pinene level. Three sympatric coniferous nonhosts each have the same attractive monoterpenes but produce less resin. These studies demonstrate the importance of chirality of host compounds in the host finding behavior of this bark beetle.

Rust-red grain beetle,Cryptolestes ferrugineus, and flat grain beetle,Cryptolestes pusillus: Antennal and behavioral responses to synthetic components of their aggregation pheromones.

Antennal and behavioral responses of the rust-red grain beetle,Cryptolestes ferrugineus, and the flat grain beetle,C. pusillus, to synthetic samples of the macrocyclic lactones reported to comprise their aggregation pheromones were investigated. Electroantennogram (EAG) recordings were obtained successfully from both species for the first time. Females of both species showed larger EAGs than males. The EAGs ofC. ferrugineus showed a high degree of specificity for conspecific aggregation pheromone components;C. pusillus showed much less specificity. Behavioral tests were conducted using two-choice pitfall bioassays. Separation of the results into the two effects of activity stimulation and direction finding showed that both effects contributed to the overall response, although sometimes to different extents. The strain ofC. pusillus studied responded equally well to both components of its pheromone, whereas it had been reported previously that only one was active, the other acting as a Synergist and eliciting no response when tested alone. With both species, behavioral response was elicited with a single lactone, suggesting that it might not be necessary to use both components for field use. Particularly surprising was thatC. pusillus showed a greater response to the pheromone components ofC. ferrugineus than to its own. Aeration of the two species and thermal desorption of the collected volatiles confirmed production of the expected lactones, and aeration of authentic lactones showed that the response was not due to the C.ferrugineus pheromone components being markedly more volatile. This response, which seems to be an actual preference, is the first to be discovered among the cucujid beetles and encourages optimism that a practical lure for various species may not need to be as complex as originally feared.

Saw-toothed grain beetleOryzaephilus surinamensis (L.) (Coleoptera: Silvanidae) : Collection, identification, and bioassay of attractive volatiles from beetles and oats.

Over 200 beetle- and food-produced volatiles were collected from cultures of the saw-toothed grain beetleOryzaephilus surinamensis (L.) on oats. It proved possible to develop the electroantennogram recording technique for these beetles, despite their small size, allowing volatiles causing antennal responses to be identified by coupled GC-EAG and subsequent GCMS techniques. Three beetle-produced macrolide lactones were identified as (Z,Z)-3,6-dodecadien-11-olide, (Z,Z)-3,6-dodecadienolide, and (Z,Z)-5,8-tetradecadien-13-olide in an average ratio of 4.4∶1∶2. These have been reported as components of the aggregation pheromone from a different population of this species, although the ratio of the components produced was different. Three food volatiles with EAG activity were also identified: 1-octen-3-ol, 3-octanone, and nonanal. A mixture of the six identified volatiles produced similar levels of attraction, in a behavioral assay, to the entire mixture of collected volatiles.

Saw-toothed grain beetleOryzaephilus surinamensis (L.) (Coleoptera: Silvanidae) : Antennal and behavioral responses to individual components and blends of aggregation pheromone.

The antennal and behavioral responses of the saw-toothed grain beetle,Oryzaephilus surinamensis, to the three components of its male-produced aggregation pheromone were investigated. EAG recordings showed no differences between the responses of the two sexes to the synthetic pheromone components. In contrast, laboratory behavioral assays demonstrated marked differences between the sexes. More females than males were consistently attracted to mixtures of the synthetic components, and this bias appeared to be caused by one component in the blend. Altering the blend ratio resulted in changes in the ratio of the sexes attracted. Thus, if, as suggested by preliminary work, males vary the blend produced, this should alter the relative response of the sexes to the aggregation pheromone.

Female sex pheromone of the common furniture beetleAnobium punctatum (Coleoptera: Anobiidae): Extraction, identification, and bioassays.

Observations and reports on the common furniture beetleAnobium punctatum suggested that, on emergence, females use a sex pheromone to attract males. GLC analysis of ovipositor extracts showed the presence of a single component, which was found to be active by EAG and coupled GLC-EAG techniques, and to attract males in both walking and flying assays. The pheromone was identified by GC-MS as 2,3-dihydro-2,3,5-trimethyl-6-(1-methyl-2-oxobutyl)-4H-pyran-4-one (stegobinone), which is the sex pheromone of another anobiid, the drugstore beetle,Stegobium paniceum. MaleA. punctatum responded equally to ovipositor extracts of either species, at both the sensory (EAG) and behavioral levels, which poses the question as to how species specificity in mate attraction is achieved.

A modification of pyriform fossa wiring.

The disadvantages of pyriform fossa wiring in the event of emergency release of fixation are well known. A simple modification of the technique using a Williams' Modified Eyelet Wire which overcomes these difficulties is described.

Eye protection for patients undergoing oral surgery.

The risk to the eyes during oral surgical procedures is pointed out, and a simple method of protection is described.