Fish Tail Research Articles

Multidetachment analogue models of fold reactivation in transpression: The NW Persian Gulf

Two deformation events have been documented in the NW Persian Gulf during the Late Cretaceous and the Late Cenozoic. The most distinctive feature in this part of the Persian Gulf is the reactivation of the Late Cretaceous NNE-SSW Arabian trending folds by NE-SW shortening during the Late Cenozoic Zagros orogeny. In general, if a set of folds with horizontal axes is shortened roughly parallel to its fold axis, a dome-basin fold interference pattern is produced. In the NW Persian Gulf, reactivation of some old folds occurred instead of a fold interference pattern. Reactivation may be influenced by the following factors: i) the presence of incompetent layers (i.e. evaporites), ii) a variable overburden, iii) basement faults, and iv) obliquity between the younger deformation shortening axis and fold axis. It is this last factor that we investigated by means of analogue modelling. The experimental apparatus is similar to that commonly used for experiments with brittle-ductile systems at the Laboratory of Experimental Tectonics of Geosciences Rennes. The model consisted of an alternation of ductile and brittle horizontal layers with a stratigraphy similar to the one found in the NW Persian Gulf. The model was deformed by two deformation events with an angle α between the two directions of shortening. After deformation, the resulting structure resembled a fold facing the static wall with internal thrust faults and detachment faults arranged into a geometry similar to a fish tail. In the second shortening event, the fold was reactivated without formation of an interference pattern. Moreover, the displacement on both the reactivated and newly formed faults varied between almost pure thrust faults for low α and oblique thrust faults with a strike-slip component for high α. The models suggest that the presence of incompetent layers plays an important role in fold reactivation and confirm that basement faults are not necessary.

Energy harvesting from the tail beating of a carangiform swimmer using ionic polymer–metal composites

In this paper, we study energy harvesting from the beating of a biomimetic fish tail using ionic polymer–metal composites. The design of the biomimetic tail is based on carangiform swimmers and is specifically inspired by the morphology of the heterocercal tail of thresher sharks. The tail is constituted of a soft silicone matrix molded in the form of the heterocercal tail and reinforced by a steel beam of rectangular cross section. We propose a modeling framework for the underwater vibration of the biomimetic tail, wherein the tail is assimilated to a cantilever beam with rectangular cross section and heterogeneous physical properties. We focus on base excitation in the form of a superimposed rotation about a fixed axis and we consider the regime of moderately large-amplitude vibrations. In this context, the effect of the encompassing fluid is described through a hydrodynamic function, which accounts for inertial, viscous and convective phenomena. The model is validated through experiments in which the base excitation is systematically varied and the motion of selected points on the biomimetic tail tracked in time. The feasibility of harvesting energy from an ionic polymer–metal composite attached to the vibrating structure is experimentally and theoretically assessed. The response of the transducer is described using a black-box model, where the voltage output is controlled by the rate of change of the mean curvature. Experiments are performed to elucidate the impact of the shunting resistance, the frequency of the base excitation and the placement of the ionic polymer–metal composite on energy harvesting from the considered biomimetic tail.

The dependence of propulsive performance on the slip number in an undulatory swimming fish

To investigate the dependence of propulsive performance on the slip number (signifying the ratio of swimming velocity to the phase velocity of body wave undulation) in an undulatory swimming fish, we performed two-dimensional numerical simulations for a fish swimming at various slip numbers, addressing the hydrodynamic correlation between slip number and propulsive performance. The amounts of power consumption evaluated from the numerical simulation increases for a decreasing slip number. The simulated flow fields reveal that vortex shedding has a substantial impact on the force and power consumption of a fish swimming at various slip numbers. A detouring proto-vortex shed around the fish tail produces a low- pressure kernel that beneficially results in decreased power consumption but also detrimentally causes an increased anterior–posterior pressure drag. A decreased slip number strengthens the effect of the low-pressure kernel, consequently causing an increased power consumption.

The fish tail motion forms an attached leading edge vortex.

The tail (caudal fin) is one of the most prominent characteristics of fishes, and the analysis of the flow pattern it creates is fundamental to understanding how its motion generates locomotor forces. A mechanism that is known to greatly enhance locomotor forces in insect and bird flight is the leading edge vortex (LEV) reattachment, i.e. a vortex (separation bubble) that stays attached at the leading edge of a wing. However, this mechanism has not been reported in fish-like swimming probably owing to the overemphasis on the trailing wake, and the fact that the flow does not separate along the body of undulating swimmers. We provide, to our knowledge, the first evidence of the vortex reattachment at the leading edge of the fish tail using three-dimensional high-resolution numerical simulations of self-propelled virtual swimmers with different tail shapes. We show that at Strouhal numbers (a measure of lateral velocity to the axial velocity) at which most fish swim in nature (approx. 0.25) an attached LEV is formed, whereas at a higher Strouhal number of approximately 0.6 the LEV does not reattach. We show that the evolution of the LEV drastically alters the pressure distribution on the tail and the force it generates. We also show that the tail's delta shape is not necessary for the LEV reattachment and fish-like kinematics is capable of stabilising the LEV. Our results suggest the need for a paradigm shift in fish-like swimming research to turn the focus from the trailing edge to the leading edge of the tail.

Robot Fish with Novel Wire-Driven Continuum Flapping Propulsor

This paper presents a robot fish with a novel continuum flapping propulsor. It is actuated by the biomimetic wire-driven mechanism. The fish tail is made from a continuous elastic plate. One pair of wire is used to control the tail flapping. Compared with the traditional multi-joint design, in this design the flapping motion could better fit the fish swimming curve, as a result improving the propulsion efficiency. Results show that the propulsion efficiency of the robot could reach 64.4%.

Teeth by Hannah Moskowitz (review)

Reviewed by: Teeth by Hannah Moskowitz Deborah Stevenson, Editor Moskowitz, Hannah. Teeth. Simon Pulse, 2013. [288p]. Trade ed. ISBN 978-1-4424-6532-9 $17.99 Paper ed. ISBN 978-1-4424-4946-6 $9.99 E-book ed. ISBN 978-1-4424-4947-3 $9.99 Reviewed from galleys R* Gr. 9–12. A boy lies in bed at night on an isolated rocky island, listening as the waves crash loudly against the shore—but not loudly enough to drown out the screaming that rings out across the sea every night. A mysterious girl lives in a secluded mansion that she almost never leaves, fascinating the boy. A monstrous secret from the past is enfleshed as a being that threatens the heart of the island. Those are some old-school gothic elements, but Moskowitz brings them into arresting modernity in this breathtaking, heartbreaking, wholly original tale. Sixteen-year-old Rudy, our narrator, isn’t a particularly gothic kid; he was mostly a thoughtless young guy with a fondness for mild bullying and getting laid until his five-year-old brother, Dylan, became horribly, incurably ill with cystic fibrosis. Now he and his family have come to this distant place in hope that the island’s silver Enki fish, reported to be curative, can heal Dylan, and it actually seems to be working. Diana, the daughter of the island matriarch, is the only other teenager on the island, and Rudy strikes up a flirtation with her out of lust, out of boredom, and out of interest in her vast library. But the relationship that really changes Rudy’s life is another one. The swiftly swimming guy who Rudy occasionally spots in the distance turns out to be someone—something very different up close: “webbed fingers, the scrawny torso patched with silver scales, and a twisted fish tail starting where his hips should be, curling into a dirty fin. A fish. A boy. The ugliest thing I have ever seen.” Despite being a fish-human hybrid, profane, prankish Teeth (as he calls himself for his pointy fish teeth) proves to be excellent company for a lonely human guy, and he and Rudy gradually become friends. Teeth, however, has a mission: he wants to free the Enki fish, and his attempts at sabotage make him the target of the fishermen, who beat him nightly with cruel and lethal intent. A horrified Rudi initially throws his lot in with his friend, but then the fish scarcity sends his beloved little brother back into a literally suffocating downspiral. The friends realize they’re at an impasse: the fishing that Teeth aims to prevent is the only thing keeping Rudy’s brother alive. That’s not even plumbing the full depths of this lacerating story about love and caretaking, guilt and complicity, liberation and isolation. Moskowitz writes Rudy’s narration with authentically conversational roughness and subtle craft, and characters are interestingly faceted. Rudy is deeply devoted to his family and especially to Dylan, but he also fears that the miracle of the fish means he’ll be exiled to this island for the rest of his life. Diana, the girl who knows about life only from books, is coolly intriguing. Teeth himself is fascinatingly depicted: no [End Page 281] lithe silver mermaid, he’s a doomed chimera; the result of bizarre human/fish sexual congress, he struggles on land or at sea. Under his brash insouciance, he’s innocent and longing and desperately in need, and his friendship for Rudy evolves into truly moving involvement with Dylan’s fate as well. But the ethical quandary the two friends face is utterly implacable: since Teeth is half-Enki fish, they’re weighing the value of Teeth’s brothers against Rudy’s. While Moskowitz clearly knows her literary context (even Diana’s library adds resonance), she’s never enslaved by it. This is an ungothic gothic, a harshly unmagical work of magical realism, with more in common with Chris Lynch than “The Little Mermaid,” and no matter what readers are expecting, they’re certain to find surprises. They’ll also find poignant exploration of some of life’s hardest questions, like what you sacrifice for those...

Mechanical and Thermo-Physical Properties of Fish Tail Palm Tree Natural Fiber–Reinforced Polyester Composites

The main objective of this article is to introduce a newly identified fish tail palm tree natural fiber as reinforcement in the development of partially biodegradable green composites. The tensile strength, tensile modulus, and impact strength of the composite are 1.54, 1.83, and 9.8 times greater than those of pure resin, respectively. The thermal conductivity of the composite decreased with increase in fiber content and the opposite trend was observed for temperature. The effect of temperature on specific heat capacity and thermal diffusivity of the composite was also considered and discussed.

1D07 魚の尾鰭形状と推進力に関する研究(OS10-2:生物の遊泳と飛翔(2))

1D07 魚の尾鰭形状と推進力に関する研究(OS10-2:生物の遊泳と飛翔(2))

Extraction of Oil from Mackerel Fish Processing Waste using Alcalase Enzyme

After removing the flesh during fish processing operations, all other parts are considered waste which is not properly utilized. Fish and fish waste can be used to produce oil for further production of omega-3 fatty acids, and/or biodiesel. Fish oil is found in the flesh, head, frames, fin, tail, skin and guts of fish in varying quantities. In this study, enzymatic extraction of fish oil was carried out using alcalase enzyme at three enzyme concentrations (0.5, 1 and 2%) and four time intervals (1, 2, 3 and 4 h). The highest oil yield was obtained from the head and the lowest oil yield was obtained from the frame. The oil obtained after enzymatic hydrolysis was dark in color due to the formation of brown pigments from the reaction of carbonyls produced from oxidation of polyunsaturated fatty acids with amino acids and proteins. The addition of buffer during the hydrolysis played an important role, as it increased the formation of emulsion, decreased the production of free oil and increased the recovery of soluble proteins. The initial heating of raw material played an important role as it helped to increase the oil yield, but it would have been more effective if no water or buffer was added to the system. The highest oil yield (76.26% from head and 75.71% from the whole fish) was obtained using 2.0% enzyme concentration after 4 h of hydrolysis. The results showed that increasing the enzyme concentration by from 0.5 to 2% (400%) increased the oil yield by 0.10-63.71%, depending upon the fish part and reaction time used. Increasing the enzyme concentration for a small increase in oil yield may appear unjustified. Therefore, the concentration of 0.5% should be used for the oil extraction, unless the enzyme is recycled or an immobilized reactor is used in order to reduce the cost associated with the enzyme. The results also showed that increasing the reaction time by from 1 to 4 h (400%) increased the oil yield by 26.62-59.29%, depending upon the fish part and enzyme concentration used. Increasing the time for a small increase in oil yield will increase the capital and operating costs of production. A shorter reaction time will allow more throughputs, and/or reduce the volume of the reactor, thereby reducing the cost of oil extraction. Therefore, a 1 h reaction time for oil extraction is recommended.

Trailing edge shock modulation by pulsating coolant ejection

In transonic and supersonic turbomachinery, shock waves appear at the trailing edge, generating substantial losses due to the interaction with the boundary layer. A novel proposal to control the resulting fish tail shock waves consists on, pulsating coolant blowing through the trailing edge of the airfoils. This paper presents an unprecedented experimental and numerical research. A linear cascade representative of modern turbine bladings was specifically designed and constructed. The test matrix comprised four Mach numbers, from subsonic to supersonic regimes (0.8, 0.95, 1.1 and 1.2) together with two engine representative Reynolds numbers (4 and 6 × 106) at various blowing rates. The blade loading and the downstream pressure distributions allowed understanding the effects on each leg of the shock structure. Minimum shock intensities were achieved using pulsating cooling. A substantial increase in base pressure was observed for low coolant blowing rate. Analysis of the high-frequency Schlieren pictures revealed the modulation of the shock waves with the coolant pulsation. The Strouhal number of the vortex shedding was analyzed for all of the conditions.

Diet and scavenging habits of the smooth skate Dipturus innominatus

The diet of smooth skate Dipturus innominatus was determined from examination of stomach contents of 321 specimens of 29·3-152·0 cm pelvic length, sampled from research and commercial trawlers at depths of 231-789 m on Chatham Rise, New Zealand. The diet was dominated by the benthic decapods Metanephrops challengeri and Munida gracilis, the natant decapod Campylonotus rathbunae and fishes from 17 families, of which hoki Macruronus novaezelandiae, sea perch Helicolenus barathri, various Macrouridae and a variety of discarded fishes were the most important. Multivariate analyses indicated the best predictors of diet variability were D. innominatus length and a spatial model. The diet of small D. innominatus was predominantly small crustaceans, with larger crustaceans, fishes and then scavenged discarded fishes increasing in importance as D. innominatus got larger. Scavenged discards were obvious as fish heads or tails only, or skeletal remains after filleting, often from pelagic species. Demersal fish prey were most frequent on the south and west Chatham Rise, in areas where commercial fishing was most active. Dipturus innominatus are highly vulnerable to overfishing, but discarding practices by commercial fishing vessels may provide a positive feedback to populations through improved scavenging opportunities.

Management of neglected lateral condyle fractures of humerus in children: A retrospective study

Background:Late presentation of humeral lateral condylar fracture in children is a surgical dilemma. Osteosynthesis of the fracture fragment or correction of elbow deformity with osteotomies and ulnar nerve transposition or sometimes both procedures combined is a controversial topic. We retrospectively evaluated open reduction and fixation cases in late presentation of lateral humeral condyle fracture in pediatric cases with regards to union and functional results.Materials and Methods:Twenty two pediatric (≤12 years) patients with fractures of lateral condyle presenting 4 weeks or more post injury between the study period of 2006 and 2010 were included. Multiple K-wires / with or without screws along with bone grafting were used. At final evaluation, union (radiologically) and elbow function (Liverpool Elbow Score, LES) was assessed.Results:There were 19 boys and 3 girls. Followup averaged 33 months. Pain (n=9), swelling (n=6), restriction of elbow motion (n=6), prominence of lateral condylar region (n=4), valgus deformity (n=4) were the main presenting symptoms. Ulnar nerve function was normal in all patients. There were nine Milch type I and 13 type II fractures. Union occurred in 20 cases. One case had malunion and in another case there was resorption of condyle following postoperative infection and avascular necrosis. Prominent lateral condyles (4/12), fish tail appearance (n=7), premature epiphyseal closure (n=2) were other observations. LES averaged 8.12 (range, 6.66-9.54) at final followup.Conclusions:There is high rate of union and satisfactory elbow function in late presenting lateral condyle fractures in children following osteosynthesis attempt. Our study showed poor correlation between patient's age, duration of late presentation or Milch type I or II and final elbow function as determined by LES.

Fish tail resection for treating congenital entropion in Asians

PrefaceThe Asian race has a high prevalence of congenital entropion. It was reported that over 20% of Japanese children have congenital entropion at the age of 1 year. One of the structural causes of this condition is the development of epiblepharon, which attaches the lower eyelid to the upper eyelid, and is also common among Asians. However, designing a procedure for modifying an epicanthus flap is relatively difficult, and epicanthoplasty is not a popular procedure in Japan. In the present study, we developed an easy method of designing the surgery, and we describe both the surgical procedure and the outcome.CasesBetween January 2010 and August 2011, one surgeon performed surgery to correct congenital entropion in 28 patients. We analyzed this series of 28 cases retrospectively. The patients consisted of 17 females and eleven males with an average age of 7.6 years. Ten patients with a thick epicanthal fold required epicanthoplasties in addition to lower lid procedures, and 18 patients with a thin epicanthal fold required only lower lid procedures.Surgical methodOn the epicanthus, a small, triangular “fish-tail” flap that was 2 mm wide was designed and was located adjacent to a “fish-body” marking on the subciliary lower eyelid. After fish-tail resection, the residual medial edge was sutured to the corner of the epicanthus. A C-shaped epicanthus was changed into an L-shape by means of this procedure.ResultThe fish-tail resection diminished the tension of the orbicularis in the superior direction. After a minimum of 6 months, the shape of the medial canthus remained L-shaped, and the cilia had stable orientations.ConclusionThis plasty is easy to design in conjunction with a Hotz procedure, and it is an effective means of correcting Asian congenital entropion. Recognizing the shape of a congenital entropion that is accompanied by epiblepharon is important for its radical treatment.

입자영상유속계를 이용한 은어 (Plecoglossus altivelis)의 유영능력 측정

As a fish way is a structure for fish migrating well toward upper stream due to breaking river flow by a dam or dammed pool, the specific fish's swimming ability is one of the main factors in making a plan and managing it. In addition, it also needs to understand the current field in fish road to evaluate its performance. This study is aimed to analyze the swimming patterns with current velocity changes using a Particle Imaging Velocimetry (PIV) in order to understand the swimming ability of silver fish (Plecoglossus altivelis) that is one of the fishes migrating through the fish way of Nakdong River, and to analyze the 2 dimensional current field near to silver fish at swimming momentum. The results showed that average values of tail beat frequencies for continuous swimming with current velocity were 2.8 Hz at 0.3 m/s, 3.2 Hz at 0.4 m/s, 3.8 Hz at 0.5 m/s, respectively. The wake would be produced by direction turning of fish's tail fin and its magnitude would be verified by the difference of pressure. The pressure turbulent flow produced by its tail beat would be made in both sides, and then, the magnitude of wake should be the source of moving direction. The swimming momentum will help to support the primary factor in making a suitable design for specific fish species migrating toward the district river.

A New Skin Excision Pattern To Correct Protruding Earlobe Deformity in Prominent Ears

IntroductIon: Correction of the earlobe protrusion is challenging problem in prominent ear cases because of the dependence of only skin excision procedures instead of cartilage reshaping methods. Fish tail skin excision is usually performed, but the results don’t always satisfactory. We excised extra triangle shape skin islands to deal with this problem MethodS: We use this method in five prominent ear cases. We drew one or more triangle after planned of the skin excision line at the posterior aspect of the ear. The base of the triangle placed to the outer line of the elliptical excision or fish tail excision. We excised of this triangle shaped skin islands besides of the elliptical skin excision. reSultS: Results of the operations were satisfactory. We could obtain better earlobe position in the prominent ear cases. concluSIon: Surgical techniques for the correction of prominent ears can be grouped into operations that involve excision of cartilage, molding the ear with sutures, molding the ear with sculpting of cartilage, or a combination of any of the above. Anyone or combination of these methods usually correct the deformity of prominent ear. In most of the cases, elliptical skin excision is carried out at the postauricular region, thus excess skin is removed, and it helps to maintain the new position of the ear. However, fish tail skin excision is performed same time to correct of the earlobe protrusion. But, fish tail skin excision usually provides inadequate correction in protruding earlobes. Because there is plenty skin at the posterior aspect of the earlobe, and almost in all skin must be removed to successful set back. However we added one or more triangle shape skin excision which its apex to the helical margin with the fish tail excision, and we could obtain better earlobe position.

Visual Comparability of 3D Regular Sampling and Reconstruction

The Body-Centered Cubic (BCC) and Face-Centered Cubic (FCC) lattices have been analytically shown to be more efficient sampling lattices than the traditional Cartesian Cubic (CC) lattice, but there has been no estimate of their visual comparability. Two perceptual studies (each with N = 12 participants) compared the visual quality of images rendered from BCC and FCC lattices to images rendered from the CC lattice. Images were generated from two signals: the commonly used Marschner-Lobb synthetic function and a computed tomography scan of a fish tail. Observers found that BCC and FCC could produce images of comparable visual quality to CC, using 30-35 percent fewer samples. For the images used in our studies, the L(2) error metric shows high correlation with the judgement of human observers. Using the L(2) metric as a proxy, the results of the experiments appear to extend across a wide range of images and parameter choices.

A New Skin Excision Pattern to Correct Protruding Earlobe Deformity in Prominent Ears

IntroductIon: Correction of the earlobe protrusion is challenging problem in prominent ear cases because of the dependence of only skin excision procedures instead of cartilage reshaping methods. Fish tail skin excision is usually performed, but the results don’t always satisfactory. We excised extra triangle shape skin islands to deal with this problem MethodS: We use this method in five prominent ear cases. We drew one or more triangle after planned of the skin excision line at the posterior aspect of the ear. The base of the triangle placed to the outer line of the elliptical excision or fish tail excision. We excised of this triangle shaped skin islands besides of the elliptical skin excision. reSultS: Results of the operations were satisfactory. We could obtain better earlobe position in the prominent ear cases. concluSIon: Surgical techniques for the correction of prominent ears can be grouped into operations that involve excision of cartilage, molding the ear with sutures, molding the ear with sculpting of cartilage, or a combination of any of the above. Anyone or combination of these methods usually correct the deformity of prominent ear. In most of the cases, elliptical skin excision is carried out at the postauricular region, thus excess skin is removed, and it helps to maintain the new position of the ear. However, fish tail skin excision is performed same time to correct of the earlobe protrusion. But, fish tail skin excision usually provides inadequate correction in protruding earlobes. Because there is plenty skin at the posterior aspect of the earlobe, and almost in all skin must be removed to successful set back. However we added one or more triangle shape skin excision which its apex to the helical margin with the fish tail excision, and we could obtain better earlobe position.

Salmonid influences on rivers: A geomorphic fish tail

Studies of the effects of salmonids on the environment have focused primarily on the biological linkages between salmon runs and stream ecology. Less effort has focused on geomorphic effects. A review of the literature indicates potential (i) direct effects in response to mass spawning of salmonids, including changes in streambed and bank morphology and annual volumes of bedload transported; and (ii) indirect effects including supply of nutrients to the riparian zone, which may influence the in-channel dynamics of large woody debris and bank stability, and effects on population density of net-spinning caddisfly larvae which may influence streambed stability in finer gravel substrates. More research is needed over long time frames, however, to ascertain whether such effects are geomorphically significant at larger spatial and longer temporal scales, and to estimate the sizes of populations required to cause geomorphically significant responses. Some possible studies are suggested.

Use of multifocal ERG and OCT for diagnosing Stargardt's disease

Stargardt’s disease (Stargardt’s macular dystrophy, juvenile macular degeneration) was originally described by Stargardt in the early 1900s and is known as the most common congenital macular dystrophy, with an incidence of one in every 10,000. Stargardt’s disease (STGD) is characterised as a widespread lipofusin storage disease of the retinal pigment epithelium (RPE). Typically, it presents between the first to third decades of life and is associated with a progressive, bilateral decrease in visual acuity leading to legal blindness and central visual acuity of 6/60 to 6/120. Though it is typically associated with an autosomal recessive (AR) inheritance pattern, autosomal dominant (AD) cases have been reported with later onset and less severe acuity loss. Classic findings include bilateral macular changes that begin as granular mottling with progression toward a ‘beaten bronze’ maculopathy. The late stage of the disease is associated with macular atrophic degeneration. Yellow-white flecks in the posterior pole may be noted; they are described as tri-radiating ‘fish tail’ (pisciform) flecks. Traditionally, Stargardt’s disease has been diagnosed through clinical evaluation and fluorescein angiography (IVFA), which demonstrates a dark or ‘silent’ choroid due to the blockage of the fluorescein by the lipofusin deposition in the RPE. Though fluorescein angiography has been considered the ‘gold standard’ in verifying the presence of the disease, the characteristic dark choroid pattern is seen in only 85 per cent of patients with Stargardt’s disease. There have been reports of patients with autosomal dominant inheritance pattern who fail to demonstrate this classic fluorescein angiography finding. Newer and minimally invasive procedures, such as the multifocal electroretinogram (mfERG) and optical coherence tomography (OCT), may aid in diagnosing and managing patients with the disease. These ancillary tests may be used in the event that fluorescein angiography cannot be performed or used in conjunction with traditional fluorescein angiography as a complementary procedure. Multifocal electroretinography (mfERG) is a minimally invasive procedure that has been shown to be helpful in the diagnosis of Stargardt’s disease. Unlike traditional flash electroretinography (fERG), this technology has proved extremely reliable in diagnosing and monitoring various forms of macular dystrophy. In the case of Stargardt’s disease, the patient presents with significant variation in presentation; from normal to reduced acuity, minimal to significant fundus findings and normal to slightly reduced full field flash electrophysiological findings. Regardless of the presentation, Stargardt’s patients typically have a significant reduction of the foveal response and central approximately 10 degrees in both eyes on mfERG, even early in the disease process with relatively good visual acuity and minimal fundus findings. In addition to electrophysiology, retinal imaging technology such as OCT has proved effective in correlating structural damage with functional visual loss. The OCT findings of patients with Stargardt’s disease include decreased thickness of the retina, most notably in the foveola. The OCT also reveals photoreceptor loss and external nuclear layer changes, as well as abnormalities in the retinal pigment epithelium.

Volumetric imaging of fish locomotion

Fishes use multiple flexible fins in order to move and maintain stability in a complex fluid environment. We used a new approach, a volumetric velocimetry imaging system, to provide the first instantaneous three-dimensional views of wake structures as they are produced by freely swimming fishes. This new technology allowed us to demonstrate conclusively the linked ring vortex wake pattern that is produced by the symmetrical (homocercal) tail of fishes, and to visualize for the first time the three-dimensional vortex wake interaction between the dorsal and anal fins and the tail. We found that the dorsal and anal fin wakes were rapidly (within one tail beat) assimilated into the caudal fin vortex wake. These results show that volumetric imaging of biologically generated flow patterns can reveal new features of locomotor dynamics, and provides an avenue for future investigations of the diversity of fish swimming patterns and their hydrodynamic consequences.