Wireless recording of the calls of Rousettus aegyptiacus and their reproduction using electrostatic transducers.

Bats are capable of imaging their surroundings in great detail using echolocation. To apply similar methods to human engineering systems requires the capability to measure and recreate the signals used, and to understand the processing applied to returning echoes. In this work, the emitted and reflected echolocation signals of Rousettus aegyptiacus are recorded while the bat is in flight, using a wireless sensor mounted on the bat. The sensor is designed to replicate the acoustic gain control which bats are known to use, applying a gain to returning echoes that is dependent on the incurred time delay. Employing this technique allows emitted and reflected echolocation calls, which have a wide dynamic range, to be recorded. The recorded echoes demonstrate the complexity of environment reconstruction using echolocation. The sensor is also used to make accurate recordings of the emitted calls, and these calls are recreated in the laboratory using custom-built wideband electrostatic transducers, allied with a spectral equalization technique. This technique is further demonstrated by recreating multi-harmonic bioinspired FM chirps. The ability to record and accurately synthesize echolocation calls enables the exploitation of biological signals in human engineering systems for sonar, materials characterization and imaging.

Phragmoplast-mediated cytokinesis in Trentepohlia: results of TEM and immunofluorescence cytochemistry.

This paper reports transmission electron microscopy (TEM) and immunofluorescence evidence for phragmoplast-mediated cytokinesis in the green alga, Trentepohlia (Ulvophyceae, Chlorophyta). This type of cytokinesis is normally found only in land plants and some charophycean green algae. Earlier TEM work documented a phragmoplast in another trentepohlialean alga, Cephaleuros. Numerous molecular studies have shown that both Trentepohlia and Cephaleuros are clearly not in the charophycean (streptophyte) lineage of green algae. Also, details of vegetative cytokinesis in Trentepohlia and Cephaleuros indicate differences from the processes and structures observed in the streptophytes. Parallel evolution could be the explanation for a phragmoplast-mediated cytokinesis in both the chlorophycean Trentepohliales and the streptophyte lineage of charophycean green algae and land plants.

The synchronisation of signal emission with wingbeat during the approach phase in soprano pipistrelles (Pipistrellus pygmaeus).

Previous studies have shown that, during search flight in bats, wingbeat, respiration and echolocation are synchronised in a 1:1 relationship. An efficiently integrated locomotor-respiratory system enables bats to produce intense echolocation signals at little or no cost above that required for flight. In this study, we investigated the coupling of wingbeat with echolocation in the laboratory during approach flight in soprano pipistrelles (Pipistrellus pygmaeus) using high-speed digital video at 250 and 500 frames s(-)(1). We found that soprano pipistrelles most commonly produce single or double pulses per wingbeat. Single pulses per wingbeat occurred in two alternative positions: immediately before the end of the upstroke or after the start of the downstroke. Double pulses per wingbeat were emitted in the same wingbeat positions on the upstroke and the downstroke, as in single pulses per wingbeat. We suggest that, during approach flight, the coupling of more than one echolocation signal with a single wingbeat and expiratory cycle allows echolocation to remain energetically economic. When soprano pipistrelles approached a Perspex disc target, an increase in mean repetition rate was achieved by producing an extra pulse per wingbeat. Finally, we hypothesise that the bat's approach to potentially interesting targets in the same horizontal plane as it's flight path, i.e. during flapping flight, may be characterised by the production of double pulses per wingbeat, resulting in a unique pattern of echolocation pulse intervals.

Moth hearing in response to bat echolocation calls manipulated independently in time and frequency.

We measured the auditory responses of the noctuid moth Noctua pronuba to bat echolocation calls which were manipulated independently in time and frequency. Such manipulations are important in understanding how insect hearing influences the evolution of echolocation call characteristics. We manipulated the calls of three bat species (Rhinolophus hipposideros, Myotis nattereri and Pipistrellus pipistrellus) that use different echolocation call features by doubling their duration or reducing their frequency, and measured the auditory thresholds from the A1 cells of the moths. Knowing the auditory responses of the moth we tested three predictions. (i) The ranking of the audibility of unmanipulated calls to the moths should be predictable from their temporal and/or frequency structure. This was supported. (ii) Doubling the duration of the calls should increase their audibility by ca. 3 dB for all species. Their audibility did indeed increase by 2.1-3.5 dB. (iii) Reducing the frequency of the calls would increase their audibility for all species. Reducing the frequency had small effects for the two bat species which used short duration (2.7-3.6 ms) calls. However, the relatively long-duration (50 ms), largely constant-frequency calls of R. hipposideros increased in audibility by 21.6 dB when their frequency was halved. Time and frequency changes influence the audibility of calls to tympanate moths in different ways according to call design. Large changes in frequency and time had relatively small changes on the audibility of calls for short, largely broadband calls. Channelling energy into the second harmonic of the call substantially decreased the audibility of calls for bats which use long-duration, constant-frequency components in echolocation calls. We discuss our findings in the contexts of the evolution of both bat echolocation call design and the potential responses of insects which hear ultrasound.

Echolocation call structure and intensity in five species of insectivorous bats.

Echolocation call intensity was measured in the laboratory for five species of British insectivorous bats in free flight and in the hand. All species showed similar call intensities of between 80 and 90 dB peSPL (peak equivalent SPL) at 1 m during flight except Plecotus auritus, whose call intensity was between 68 and 77 dB peSPL at 1 m. Calls from stationary bats were about 13 dB less intense than calls during flight. A method is proposed to measure the root mean square (rms) amplitude of echolocation calls and, hence, to calculate the energy flux density of the call. The constant-frequency calls of Rhinolophus hipposideros have energy flux densities approximately ten times higher than those of bats using frequency-modulated calls as a result of their longer durations and lower crest factors. It is argued that the low-intensity calls of P. auritus allow it to approach tympanate moths more closely before triggering their escape response.

Locked intramedullary nailing of humeral shaft fractures. Implant design, surgical technique, and clinical results.

We report our experience with a modified implant and a new technique for locked intramedullary nailing of the humerus in 41 patients. Locking was by cross-screws placed from lateral to medial in the proximal humerus, and anteroposteriorly in the distal humerus. Early in the series, 11 nails were inserted at the shoulder, but we found that rehabilitation was faster after retrograde nailing through the olecranon fossa, which was used for the other 30. We used a closed technique for 29 of the nailings. Of the 41 patients treated, 21 had acute fractures, five had nonunion, and 15 had pathological fractures. Secure fixation was obtained for comminuted and osteoporotic fractures in any part of the humeral shaft, which allowed the early use of crutches and walking frames. Two nails were locked at only one end, and one of these became the only failure of union after an acute fracture.

Regulation of the Bacillus subtilis acetate kinase gene by CcpA.

The Bacillus subtilis gene encoding acetate kinase was identified on the basis of sequence similarity to the Escherichia coli ackA gene and to a second E. coli gene closely related to ackA. Insertional inactivation of this region of the B. subtilis chromosome resulted in the disappearance of acetate kinase enzyme activity in cell extracts. The ackA gene was mapped to a site close to the ccpA gene, at 263 degrees. The transcriptional start site for B. subtilis ackA was located 90 bp upstream from the start of the coding region, and expression was increased by growth in the presence of excess glucose. Growth of the AckA- mutant was inhibited by glucose, suggesting that acetate kinase is important for excretion of excess carbohydrate. The stimulation of ackA expression by glucose was blocked in a CcpA- mutant, indicating that CcpA, which is required for glucose repression of certain carbon source utilization genes, including amyE, may also be involved in activation of carbon excretion pathways. Two sequences resembling the amyO operator site were identified upstream of the ackA promoter; removal of this region resulted in loss of glucose activation of ackA expression.

Identification of genes involved in utilization of acetate and acetoin in Bacillus subtilis.

The Bacillus subtilis ccpA gene has previously been shown to be involved in repression of amyE expression when cells are grown in excess glucose. The region of the B. subtilis chromosome downstream from ccpA was characterized to determine if additional genes involved in carbohydrate metabolism were present. Two open reading frames that exhibited sequence similarity to the Escherichia coli and B. subtilis motA and motB motility genes were found immediately downstream from ccpA; disruption of this region had no effect on growth, sporulation or motility. Two divergent transcriptional units containing the acsA and acuABC genes were also found in this region. The acsA gene encodes acetyl-CoA synthetase, and inactivation of this gene resulted in loss of the ability to utilize acetate as a carbon source for growth or sporulation. Disruption of the acuABC genes resulted in poor growth or sporulation on acetoin or butanediol. The acsA and acuABC promoter sequences were identified by primer extension, and are in close proximity. Two sequences resembling the amyO regulatory target site necessary for glucose repression of amyE were identified in the acsA-acuABC promoter regions.

Evaluation of the Hemalog D differential leucocyte counter.

The main objectives of the evaluation were to (1) establish 'normal values' for the Hemalog D, (2) compare the Hemalog D with existing manual procedures, and (3) assess the machine's reliability. It proved to be a practical machine in a routine haematology laboratory. Comparison with established techniques showed systematic differences in the total white blood cell count and percentages of lymphocytes. An existing laboratory computer system was used to collect and file the data.

Diaphragmatic hernia caused by trauma: experience with 35 cases.

Traumatic diaphragmatic hernia often is not recognized after the initial injury. Early recognition of this entity is of utmost importance since obstruction, strangulation, hemorrhage, viscus perforation, pleural fistula and empyema may occur at any time following the diaphragmatic disruption. A high index of suspicion, history of previous thoracoabdominal trauma, physical examination of the chest and roentgenographic evidence should aid in early and definitive diagnosis. Right-sided herniation should be considered in the differential diagnosis of masses about the right lower lung or diaphragm. Bilateral ruptures may also be encountered. Operation should be performed as soon as the diagnosis is made. In general, transabdominal route should be used in acute ruptures while chronic herniation should be approached through the chest.