bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental studies of the material properties of the forewing of cicada(Homóptera, Cicàdidae)
Authors: Song F. , Lee K. L. , Soh A. K. , Zhu F. , Bai Y. L. 
Published: July 2004

SUMMARYDetailed investigations on the structural and mechanical properties of the forewing of the cicada were carried out. Measurement of the structures of the wings showed that the thickness of the membrane of each cell and the diameter of each vein were non-uniform in both the longitudinal and transverse directions, and their means were approximately 12.2 and 133.3 μm,respectively. However, the aspect ratios of the wings and the bodies were quite uniform and were approximately equal to 2.98 and 2.13, respectively. Based on the measured thickness, mass and area of the membranes of the cells,the mean density and the mean area density of the wing were approximately 2.3 g cm-3 and 2.8×10-3 g cm-2,respectively. In addition, the diameters of the veins of the wings, including the diameters of the holes in the vein of the leading edge, were examined. The mechanical properties of the wing were investigated separately by nanoindentation and tensile testing. The results indicated that the mean Young's modulus, hardness and yield stress of the membranes of the wings were approximately 3.7 GPa, 0.2 GPa and 29 MPa, respectively, and the mean Young's modulus and strength of the veins along the direction of the venation of wings were approximately 1.9 GPa and 52 MPa, respectively. Finally, the relevant results were briefly analyzed and discussed, providing a guideline to the biomimetic design of the aerofoil materials of micro air vehicles.
To freeze or not to freeze: adaptations for overwintering by hatchlings of the North American painted turtle
Authors: Packard Gary C. , Packard Mary J. 
Published: July 2004

SUMMARYMany physiologists believe that hatchling painted turtles (Chrysemys picta) provide a remarkable, and possibly unique, example of `natural freeze-tolerance' in an amniotic vertebrate. However, the concept of natural freeze-tolerance in neonatal painted turtles is based on results from laboratory studies that were not placed in an appropriate ecological context,so the concept is suspect. Indeed, the weight of current evidence indicates that hatchlings overwintering in the field typically withstand exposure to ice and cold by avoiding freezing altogether and that they do so without benefit of an antifreeze to depress the equilibrium freezing point for bodily fluids. As autumn turns to winter, turtles remove active nucleating agents from bodily fluids (including bladder and gut), and their integument becomes a highly efficient barrier to the penetration of ice into body compartments from frozen soil. In the absence of a nucleating agent or a crystal of ice to `catalyze'the transformation of water from liquid to solid, the bodily fluids remain in a supercooled, liquid state. The supercooled animals nonetheless face physiological challenges, most notably an increased reliance on anaerobic metabolism as the circulatory system first is inhibited and then caused to shut down by declining temperature. Alterations in acid/base status resulting from the accumulation of lactic acid may limit survival by supercooled turtles, and sublethal accumulations of lactate may affect behavior of turtles after the ground thaws in the spring. The interactions among temperature,circulatory function, metabolism (both aerobic and anaerobic), acid/base balance and behavior are fertile areas for future research on hatchlings of this model species.
The electric fish Brachyhypopomus pinnicaudatus produces jamming avoidance responses to signals that are harmonically related to its own discharges
Authors: Capurro Alberto , Pakdaman Khashayar 
Published: July 2004

SUMMARY
Jamming avoidance responses (JARs) are exhibited by pairs of pulse type electric fish that discharge with similar frequencies whenever their individual pulses are about to coincide: responses consist of the transient shortenings in inter-discharge intervals in the fish with the higher frequency. This study describes and models novel forms of JARs observed in sexually mature male or female Brachyhypopomus pinnicaudatus.
One novel JAR was observed in male-female pairs in their natural habitat. It happened when the baseline frequencies were not similar but, rather, when one was almost twice that of the other; moreover, the transient interval shortenings occurred not in the fish with the higher frequency but in the slower one.
Transient interval shortenings similar to those in all natural JARs were observed in individual fish in tanks and submitted to periodic electrical pulse trains. They happened not only when pulse frequencies were slightly lower than the unperturbed frequency emitted by the fish but also when slightly lower than the frequency's sub- or higher harmonics (e.g. one half or twice).
The proposed model satisfactorily reproduces all experimental observations. In it, forthcoming inter-pulse intervals reflect the differences between the cophases of pulses that arrive within the `sensitive windows' belonging to either consecutive (i.e. one and the next) or alternating (e.g. every other,every three) intervals.
Paired pulse fish embody interacting oscillators, and, in particular, JARs embody either quasiperiodic phase walk-throughs and intermittencies or periodic and locked forms. Hence, their study would profit by the powerful theories and approaches advanced by nonlinear dynamics.
Ontogenesis of the attachment ability in the bugCoreus marginatus(Heteroptera, Insecta)
Authors: Gorb Stanislav N. , Gorb Elena V. 
Published: July 2004

SUMMARYEach tarsus of Coreus marginatus L. (Coreidae) bears a pair of smooth flexible pulvilli adapted for attachment to relatively smooth surfaces,such as their host plant Rumex crispus L. (Polygonaceae). This account quantifies insect attachment abilities on smooth surfaces at various stages of ontogenesis. Friction (shear) force (FF) of adults and juvenile insects was measured by the use of a computer controlled centrifugal force tester equipped with a fibre optical sensor. Pad area, body size and body mass were determined individually for each experimental insect. Light microscopy revealed no difference in pulvilli area between different leg pairs. Pulvilli area demonstrated a stronger increase with increasing linear dimensions, as predicted by scaling laws. Since friction coefficient (relationship between FF and body weight) (FC) was always higher than 1, it was concluded that adhesion has strongly contributed to the measured friction. The frictional properties of pulvilli do not change during ontogenesis. Thus, only the growth of pulvilli and, therefore, the increased contact area, contribute to the increasing attachment ability in insects at later larval stages. Due to different scaling of the body mass and area of attachment organs, smaller insects attach relatively more strongly. Both FF and FC were higher in experiments in which higher angular acceleration (AC) was applied. Lateral tenacity determined individually for experimental insects and pooled for all animals and accelerations is 0.097 N m-2. These data led us to suggest that viscosity of the pad secretion and/or visco-elastic properties of the foam-like material of pulvilli play an important role in the attachment ability of insects.
Structure and properties of the glandular surface in the digestive zone of the pitcher in the carnivorous plantNepenthes ventrataand its role in insect trapping and retention
Authors: Gorb Elena , Kastner Victoria , Peressadko Andrei , Arzt Eduard , Gaume Laurence , Rowe Nick , Gorb Stanislav 
Published: July 2004

SUMMARYCarnivorous plants of the genus Nepenthes grow in nutrient-poor habitats and have evolved specialised trapping organs, known as pitchers. These are composed of different surface zones serving the functions of attraction, capture and digestion of insects, which represent a main source of nitrogen. To investigate the role of the glandular digestive zone in the trapping mechanism of the pitcher, structural, mechanical and physico-chemical studies were applied to N. ventrata and combined with insect behavioural experiments. It was found that the glandular surface is microscopically rough since it is regularly structured with multicellular glands situated in epidermal depressions. The presence of downward-directed`hoods' over the upper part of glands and sloped depressions in the proximal direction of the pitcher causes a marked anisotropy of the surface. The glandular zone surface is composed of relatively stiff material (Young's modulus, 637.19±213.44 kPa). It is not homogeneous, in terms of adhesive properties, and contains numerous areas without adhesion as well as adhesive areas differing greatly in tenacity values (range, 1.39-28.24 kPa). The surface is readily wettable with water (contact angle, 31.9-36.0°C)and has a high surface free energy (56.84-61.93 mN m-1) with a relatively high polar component (33.09-52.70 mN m-1). To examine the effect of the glandular secretion on attachment systems of insects having hairy and smooth adhesive pads, forces generated on different surfaces by Calliphora vicina flies and Pyrrhocoris apterus bugs,respectively, were measured. Flies attached equally well to both fresh and air-dried glandular surfaces whereas bugs generated a significantly lower force on the fresh glandular surface compared with the air-dried one. It is assumed that the contribution of the glandular surface to insect retention,due to its effect on insect attachment, differs depending on insect weight and the type of insect attachment system. Surface anisotropy does not facilitate effective claw interlocking so that insects possessing only claws are probably not able to cling to the glandular surface. However, stiffness of the pitcher wall material in the digestive zone can provide claw clinging viapunching of the pitcher wall by claws. Small insects lacking pads may use adhesive areas on the plant surface to attach themselves, but such solitary points with very strong adhesion possibly impede their overall locomotion and chance of escape. Pad-bearing insects are presumably able to attach to smooth parts of the glandular surface located between glands. High free surface energy of the plant substrate may promote adhesion. Gland secretion may decrease attachment ability in insects with smooth adhesive pads but not influence attachment of insects with hairy attachment systems.
The importance of the lateral line in nocturnal predation of piscivorous catfish
Authors: Pohlmann Kirsten , Atema Jelle , Breithaupt Thomas 
Published: July 2004

SUMMARY
In a previous study we showed that nocturnal piscivorous catfish track the wake left by a swimming prey fish to locate it, following past locations to detect the present location of the prey. In a wake there are hydrodynamic as well as chemical signatures that both contain information on location and suitability of the prey. In order to determine how these two wake stimuli are utilised in prey tracking, we conducted experiments in catfish in which either the lateral line or the external gustation was ablated. We found that a functional lateral line is indispensable for following the wake of swimming prey. The frequency of attack and capture was greatly diminished and the attacks that did occur were considerably delayed when the lateral line was ablated. In contrast, catfish with ablated external taste still followed the wakes of their prey prior to attacking, albeit their attacks were delayed. The external taste sense, which was reported earlier to be necessary for finding stationary (dead) food, seems to play a minor role in the localisation of moving prey. Our finding suggests that an important function of the lateral line is to mediate wake-tracking in predatory fish.
Magnetic sense in the Japanese eel, Anguilla japonica, as determined by conditioning and electrocardiography
Authors: Nishi Takaaki , Kawamura Gunzo , Matsumoto Keisuke 
Published: July 2004

SUMMARY
Magnetosensitivity of the Japanese eel, Anguilla japonica, was examined by conditioning and electrocardiography. Marine eels, river eels and farmed eels were conditioned to an imposed magnetic field ranging from 12 663 nT to 192 473 nT parallel to the fish body, which was placed along the earth's west-east axis. Electrocardiograms were recorded with electrodes placed close to the fish body inside a PVC pipe shelter. After 10-40 conditioning runs, all the eels exhibited a significant conditioned response (i.e. slowing of the heart beat) to a 192 473 nT magnetic field and even to a 12 663 nT magnetic field, respectively equivalent to 5.92× and 0.38× the horizontal geomagnetic field (32 524 nT) at our laboratory. The west-east vector of the imposed magnetic field (12 663 nT) combined with that of the geomagnetic field and produced a horizontal resultant magnetic field of 21° easterly. Therefore, Japanese eel are magnetosensitive whether they are at sea, in the river or in the farm. Results of the present study were compared with those of past studies that showed no magnetic sense in the American eel, Anguilla rostrata, and the European eel, Anguilla anguilla.
The biomechanical and neural control of hydrostatic limb movements in Manduca sexta
Authors: Mezoff Sheri , Papastathis Nicole , Takesian Anne , Trimmer Barry A. 
Published: July 2004

SUMMARY
Caterpillars are ecologically successful soft-bodied climbers. They are able to grip tightly to foliage using cuticular hooks at the tips of specialized abdominal limbs called prolegs. The neural control of proleg retraction has been examined in some detail but little is known about how prolegs extend and adduct. This is of particular interest because there are no extensor muscles or any obvious mechanisms for directing hydraulic flow into the proleg. In restrained tobacco hornworms (Manduca sexta),adduction can be evoked by stimulating mechanosensory hairs on the medial surface of the proleg. 3-D kinematics show that extension and adduction occur simultaneously through an unfolding of membrane between the pseudo segments. Hemolymph pressure pulses are not necessary to extend the proleg; instead, the pressure at the base of the proleg decreases before adduction and increases before retraction. It is proposed that these pressure changes are caused by muscles that stiffen and relax the body wall during cycles of retraction and adduction. Electromyographic recordings show that relaxation of the principal planta retractor muscle is essential for normal adduction. Extracellular nerve and muscle recordings in reduced preparations show that medial hair stimulation of one proleg can strongly and bilaterally excite motoneurons controlling the ventral internal lateral muscles of all the proleg-bearing segments. Ablation, nerve section and electromyographic experiments show that this muscle is not essential for adduction in restrained larvae but that it is coactive with the retractors and may be responsible for stiffening the body wall during proleg movements.
Postprandial increases in nitrogenous excretion and urea synthesis in the giant mudskipperPeriophthalmodon schlosseri
Authors: Ip Yuen K. , Lim Chiat K. , Lee Serene L. M. , Wong Wai P. , Chew Shit F. 
Published: July 2004

SUMMARYThe objective of this study was to determine the effects of feeding on the excretory nitrogen (N) metabolism of the giant mudskipper, Periophthalmodon schlosseri, with special emphasis on the role of urea synthesis in ammonia detoxification. The ammonia and urea excretion rates of P. schlosseri increased 1.70- and 1.92-fold, respectively, within the first 3 h after feeding on guppies. Simultaneously, there were significant decreases in ammonia levels in the plasma and the brain, and in urea contents in the muscle and liver, of P. schlosseri at 3 h post-feeding. Thus,it can be concluded that P. schlosseri was capable of unloading ammonia originally present in some of its tissues in anticipation of ammonia released from the catabolism of excess amino acids after feeding. Subsequently, there were significant increases in urea content in the muscle,liver and plasma (1.39-, 2.17- and 1.62-fold, respectively) at 6 h post-feeding, and the rate of urea synthesis apparently increased 5.8-fold between 3 h and 6 h. Increased urea synthesis might have occurred in the liver of P. schlosseri because the greatest increase in urea content was observed therein. The excess urea accumulated in the body at 6 h was completely excreted between 6 and 12 h, and the percentage of waste-N excreted as urea-N increased significantly to 26% during this period, but never exceeded 50%, the criterion for ureotely, meaning that P. schlosseriremained ammonotelic after feeding. By 24 h, 62.7% of the N ingested by P. schlosseri was excreted, out of which 22.6% was excreted as urea-N. This is the first report on the involvement of increased urea synthesis and excretion in defense against ammonia toxicity in the giant mudskipper, and our results suggest that an ample supply of energy resources, e.g. after feeding,is a prerequisite for the induction of urea synthesis. Together, increases in nitrogenous excretion and urea synthesis after feeding effectively prevented a postprandial surge of ammonia in the plasma of P. schlosseri as reported previously for other fish species. Consequently, contrary to previous reports, there were significant decreases in the ammonia content of the brain of P. schlosseri throughout the 24 h period post-feeding, accompanied by a significant decrease in brain glutamine content between 12 h and 24 h.
When vortices stick: an aerodynamic transition in tiny insect flight
Authors: Miller Laura A. , Peskin Charles S. 
Published: July 2004

SUMMARYWe have used computational fluid dynamics to study changes in lift generation and vortex dynamics for Reynolds numbers (Re) between 8 and 128. The immersed boundary method was used to model a two-dimensional wing through one stroke cycle. We calculated lift and drag coefficients as a function of time and related changes in lift to the shedding or attachment of the leading and trailing edge vortices.We find that the fluid dynamics around the wing fall into two distinct patterns. For Re≥64, leading and trailing edge vortices are alternately shed behind the wing, forming the von Karman vortex street. For Re≤32, the leading and trailing edge vortices remain attached to the wing during each `half stroke'. In three-dimensional studies, large lift forces are produced by `vortical asymmetry' when the leading edge vortex remains attached to the wing for the duration of each half stroke and the trailing edge vortex is shed. Our two-dimensional study suggests that this asymmetry is lost for Re below some critical value (between 32 and 64), resulting in lower lift forces. We suggest that this transition in fluid dynamics is significant for lift generation in tiny insects.
Functional roles of the transverse and longitudinal flagella in the swimming motility ofProrocentrum minimum(Dinophyceae)
Authors: Miyasaka Iku , Nanba Kenji , Furuya Ken , Nimura Yoshihachiro , Azuma Akira 
Published: July 2004

SUMMARYEquations describing the motion of the dinoflagellate Prorocentrum minimum, which has both a longitudinal and a transverse flagellum, were formulated and examined using numerical calculations based on hydrodynamic resistive force theory. The calculations revealed that each flagellum has its own function in cell locomotion. The transverse flagellum works as a propelling device that provides the main driving force or thrust to move the cell along the longitudinal axis of its helical swimming path. The longitudinal flagellum works as a rudder, giving a lateral force to the cell in a direction perpendicular to the longitudinal axis of the helix. Combining these functions results a helical swimming motion similar to the observed motion. Flagellar hairs present on the transverse flagellum are necessary to make the calculated cell motion agree with the observed cell motion.
Does condition of Atlantic cod (Gadus morhua) have a greater impact upon swimming performance atUcrit or sprint speeds?
Authors: Martínez M. , Bédard M. , Dutil J.-D. , Guderley H. 
Published: July 2004

SUMMARYTo compare the sensitivity of sprint and critical(Ucrit) swimming speeds to the condition of Atlantic cod(Gadus morhua) and to identify the best anatomic, behavioural and biochemical correlates of these types of swimming, we established two groups of cod that were fed or starved for 12 weeks. We evaluated sprint swimming and Ucrit performance as well as the speed at which repeated burst-coast movements began in the Ucrit test before measuring the metabolic capacities of red and white muscle sampled caudally,centrally and rostrally and the anatomic characteristics of the cod. White muscle lactate was measured directly after the Ucrit test. As expected, the twofold difference in Fulton's condition factor(0.5±0.04 for starved and 1.0±0.1 for fed cod) was accompanied by large differences in the anatomic and biochemical parameters measured. Despite the relative sparing of muscle aerobic capacity during starvation and despite the greater use of oxidative fibres during Ucritcompared with sprint swimming, these types of swimming differed by much the same extent between starved and fed cod. In the Ucrittests, white muscle lactate levels and lactate accumulation per burst-coast movement were considerably higher in fed than starved cod, suggesting more intensive use of fast muscle fibres in cod in good condition. Multiple regression analysis indicated strong correlations between Ucrit, the speed at which regular burst-coasting began and the activity of pyruvate dehydrogenase (PDH) in red muscle (both caudal and central positions). PDH activity may limit the rate of oxidative ATP production by red muscle. The activity of cytochrome c oxidase in rostral white muscle was the strongest correlate of sprint swimming,suggesting that aerobic preparation of white muscle facilitates rapid contraction. The correlation between Ucrit and sprint swimming was weak, perhaps due to inter-individual differences in sensitivity during sprint tests.
Peripheral innervation patterns and central distribution of fin chromatophore motoneurons in the cuttlefishSepia officinalis
Authors: Gaston Michelle R. , Tublitz Nathan J. 
Published: July 2004

SUMMARYBody patterning behavior in unshelled cephalopod molluscs such as squid,octopuses, and cuttlefish is the ability of these animals to create complex patterns on their skin. This behavior is generated primarily by chromatophores, pigment-containing organs that are directly innervated by central motoneurons. The present study focuses on innervation patterns and location of chromatophore motoneurons in the European cuttlefish Sepia officinalis, specifically those motoneurons that control chromatophores of the fin. The fin is known to be innervated by the large, branching fin nerve. This study further characterizes the innervation of fin chromatophores by the fin nerve, generates a reference system for the location of fin nerve branches across individuals, and localizes the neurons whose axons innervate fin chromatophores through the fin nerve. Data from extracellular stimulation of fin nerve branches in intact animals demonstrate topographic innervation of fin chromatophores, while retrograde labeling data reveal the posterior subesophageal mass of the brain as the primary location of fin chromatophore motoneurons.