The ears of butterflyfishes (Chaetodontidae): 'hearing generalists' on noisy coral reefs?

Analysis of the morphology of all three otolithic organs (sacculus, lagena and utriculus), including macula shape, hair cell morphology, density, orientation pattern, otolith morphology and the spatial relationships of the swimbladder and ear, reveals that butterflyfishes in the genera Chaetodon (which has anterior swimbladder horns) and Forcipiger (which lacks anterior swimbladder horns) both demonstrate the ear morphology typical of teleosts that lack otophysic connections, fishes that have traditionally been considered to be 'hearing generalists'.

Calculation of electromagnetic field components for a fundamental Gaussian beam.

Using a perturbative method, we carefully calculate seventh- and ninth-order expressions for electromagnetic field components for a fundamental Gaussian beam (i.e., a focused TEM00 mode laser beam) propagating in the medium analogous to vacuum. The interaction of a single electron and a focused laser pulse in vacuum has a promising application in the design of a powerful electron accelerator which could compete with the traditional ones. For this, ninth-order accuracy in the expansion describing the focused laser beam is required. When the vector potential corresponds to polarization along the direction of propagation, the number of electromagnetic field components can be reduced from 5 or 6 to 3. Furthermore, we find two rules obeyed by all orders of the vector potential, which greatly simplify the calculation procedure of the vector potential order by order, and make it possible to investigate the behavior of high orders.

The value of combining single photon emission computerised tomography and computerised tomography in the investigation of spondylolysis.

The aim of this study was to assess the diagnostic value of combining single photon emission computerised tomography (SPECT) with reverse gantry computerised tomography (rg-CT) in the investigation of spondylolysis. Patient characteristics and imaging results in 118 patients, aged 8-44 years, with low back pain (LBP) were analysed. SPECT showed increased scintigraphic uptake in 80 patients, and spondylolysis was identified on rg-CT in 53. The Cohen Kappa ratio of 0.362 (95% CI: 0.198-0.526) suggests only fair agreement for the result of increased scintigraphic activity with the finding of spondylolysis on rg-CT. We conclude that these investigations give mutually exclusive information, which leads to four diagnostic categories. When there was increased scintigraphic activity on SPECT, 58.8% (95% CI: 48.0-69.5%) of patients had spondylolysis on rg-CT. With rest from provoking activities, these lesions may heal. We interpret the findings of increased scintigraphic activity, but no spondylolysis demonstrated on rg-CT as indicating a bone stress response. These also require rest from provoking activity to prevent a stress fracture developing. In this study, 84.2% (95% CI: 72.67-95.8%) of those patients without increased activity on SPECT had no spondylolysis identified on rg-CT. These patients may need further investigations such as magnetic resonance imaging (MRI) to diagnose pathology, which typically does not involve the posterior elements--but rest from sport may not be so important. There were five patients in our study, without increased scintigraphic activity, but in whom bilateral chronic-appearing (wide separation, smooth sclerotic bone margins) spondylolyses were identified at L5. These all were anticipated from previous plain radiographs or MRI. This group will almost certainly not heal, and if the spondylolyses are the cause of pain these vertebrae will need stabilisation by surgery if physiotherapy fails.

The cusp of evolution and development: a model of cichlid tooth shape diversity.

Tooth shape is a hallmark of repeated evolutionary radiations among cichlid fishes from East Africa. Cusp shape and number vary both within populations and among closely related species with different feeding behaviors and ecologies. Here, we use histology and scanning electron microscopy to chart the developmental trajectory of tooth shape differences in fishes from Lake Malawi. We demonstrate that species with bi- or tricuspid adult (replacement) teeth initially possess a first-generation unicuspid dentition. Notably, the timing of turnover from first-generation to replacement teeth differs among species and is correlated with feeding ecology. Next, we use field data for cichlid species with adult unicuspid, bicuspid, and tricuspid teeth to demonstrate a strong and positive relationship between the number of teeth in a row and tooth shape. We discuss cichlid tooth ontogeny in the context of morphogenetic models designed to explain the developmental basis of tooth shape variation in mammals. We suggest that the dramatic differences in cichlid dentitions can be explained by variation in the expression of common activators and inhibitors acting at multiple stages of odontogenesis.

On the physics of ferroelectrics.

The main physical properties of ferroelectric crystals are described, and the macroscopic and microscopic viewpoints are discussed along with some applications, such as in capacitors and nonlinear optics. The emphasis is on physical understanding, while the mathematical level is kept to a minimum or supplemented by graphical representations to make the article more accessible.

The laterophysic connection in chaetodontid butterflyfish: morphological variation and speculations on sensory function.

The laterophysic connection is a novel specialization in chaetodontid butterflyfish, in which paired diverticula of the swim-bladder ('horns') extend anteriorly and approach or directly contact a medial fossa in the lateral line canal contained within the supracleithrum. This study examined the morphology of the laterophysic connection in eight ecologically diverse species belonging to five subgenera within Chaetodon. Two types of laterophysic connections, indirect and direct, were found among Chaetodon species. Intraspecific variation (including sexual dimorphism) in the morphology of the laterophysic connection was not found. The type of laterophysic connection is not correlated with ecological characteristics among Chaetodon species, but appears to be correlated with subgeneric affinities of Chaetodon species. The presence of swim-bladder horns probably increases pressure sensitivity to the inner ear. It is suggested that the presence of a direct laterophysic connection, and possibly an indirect laterophysic connection, imparts pressure sensitivity to the lateral line canal system as well.

Morphology and distribution of pit organs and canal neuromasts in non-teleost bony fishes.

The morphology of the pit organs and canal neuromasts of the actinopterygian Polypterus and the lungfishes Lepidosiren, Neoceratodus and Protopterus are described using light microscopy, scanning electron microscopy and transmission electron microscopy. Pit organs resemble canal neuromasts in their hair cell polarization, but they differ in size, shape, hair cell density and in the length of the kinocilia. Pit line neuromasts in Lepidosiren, Polypterus and Protopterus are arranged in dense lines, with numerous neuromasts between pores in the canal, and are an order of magnitude smaller than canal neuromasts in Polypterus. We suggest that the evolutionary transformation of canal neuromasts into superficial neuromasts occurred through the evolutionary reduction of the lateral line canals, either as the result of selection for changes in neuromast function, or as the result of non-adaptive reduction of dermal bone around the lateral line canals and their neuromasts. Protopterus (a lepidosirenid lungfish) is apparently unique among bony fishes in that it has multiple neuromasts between adjacent pores in lateral line canals on the head. An analysis of the distribution of this character among major gnathostome clades indicates that multiple canal neuromasts between pore positions is a primitive gnathostome character. Latimeria, Neoceratodus and actinopterygian fishes are characterized by an alternative character state, the presence of one canal neuromast between adjacent pores.

Neuromast morphology and lateral line trunk canal ontogeny in two species of cichlids: an SEM study.

A study of neuromast ontogeny and lateral line canal formation in Oreochromis aureus and Cichlasoma nigrofasciatum reveals the existence of two classes of neuromasts: those that arise just before hatching (presumptive canal neuromasts, dorsal superficial neuromasts, gap neuromasts, and caudal fin neuromasts) and pairs of neuromasts that arise on each lateral line scale lateral to each canal segment at the same time as canal formation. In the anterior trunk canal segment, each presumptive canal neuromast is accompanied by a dorsoventrally oriented superficial neuromast forming an orthogonal neuromast pair. It is suggested that each of these dorsoventrally oriented superficial neuromasts is homologous to the transverse superficial neuromast row described by Münz (Zoomorphology 93:73-86, '79) in other cichlids. It is further suggested that the longitudinal lines described by Münz (Zoomorphology 93:73-86, '79) are derived from the pair of superficial neuromasts that arise during canal formation. Distinct changes in neuromast topography are documented. Neuromast formation, scale formation, and lateral line canal formation are three distinct and sequential processes. The distribution of neuromasts is correlated with myomere configuration; there is always one presumptive canal neuromast on each myomere. A single scale forms beneath each presumptive canal neuromast. Canal segment formation is initiated with the enclosure of each presumptive canal neuromast by an epithelial bridge which later ossifies. The distinction of these three processes raises questions as to the causal relationships among them.

Gross morphology and evolution of the mechanoreceptive lateral-line system in teleost fishes.

The morphology and development of the mechanoreceptive lateral-line system in teleost fishes is reviewed, and the systematic distribution of defined types of lateral-line systems is summarized. The importance of an understanding of ontogeny is stressed and the roles of phylogenetic and developmental constraints in the evolution of the lateral-line system are discussed. Four types of head canal systems are identified on the basis of the relative development of the canals and the orientation of the neuromast receptors contained within them. The distribution of these patterns in the four major teleost clades is analyzed. It is suggested that a branched tubule system associated with the head canals is a primitive teleost character, while widened and reduced head canal patterns are convergent functional specializations in many taxa. The trunk canals are contained in a continuous series of lateral-line scales, and eight trunk canal patterns are described in teleosts. Given the correlation of the systematic distribution of the different trunk canal patterns, ecological habit and body shape, it appears that the trunk canals may function as a hydrodynamic monitor in swimming fishes.

Some effects of a food supplement in elderly hospital patients: a longitudinal study.

The effect of giving a food supplement for 12 weeks to 12 elderly, clinically stable, patients was investigated longitudinally. During the period of supplementation, the mean grip strength, whole blood and plasma ascorbic acid concentration, serum and red cell folic acid and plasma vitamin D concentrations increased, and decreased when the supplement was stopped. Thiamin status, as indicated by the red cell 'TPP value', also increased in response to the supplement and decreased when the supplement was stopped. It is concluded that a food supplement of the type given in this study could be useful in preventing nutrient deficiencies in old people.

Observations on gastric acid output by a three-hour histamine infusion test using maximal doses on patients with duodenal ulcer and in normal controls.

The results of a series of histamine infusion tests extended over a period of three hours in 100 patients with duodenal ulcer and in 30 normal controls showed that while in the former group acid secretion continued to rise hourly both quantitatively and qualitatively throughout each of the three-hour periods of the tests, this did not occur in the normal controls in whom acid secretion levelled off during the second hour. Assay of 30-minute aspirates in the duodenal ulcer group showed that the 90-120 minute specimen (doubled) gave a close approximation to the values obtained during the third hour and represents maximal acid secretion of the gastric mucosa.