Walking Legs Research Articles

Walking Behavior Observed inPhoxichilidium femoratum(Rathke, 1799) andNymphon brevirostreHodge 1863 Collected from Kandalaksha Bay of the White Sea, Russia

In this study, the walking behavior ofPhoxichilidium femoratumandNymphon brevirostrewas investigated using video recordings. The walking behavior ofP. femoratumwhile walking over the colonial hydroids that they normally feed on and on relatively smooth glass surfaces was observed. In the case ofN. brevirostre, only walking on smooth glass was observed. The movement of the legs while waking does not display a metachronal pattern like that observed in the true spiders. As the animals move, the walking legs on the leading side of the animal are used to pull the animal forward while those on the trailing side make little or no contribution to the motion of the animal. The promoter/remoter motions of the coxa 1-coxa 2 joint of the walking legs are involved in azimuthal changes in the body’s orientation, but not in paraxial locomotion. The extension of the tarsus and propodus segments appears to occur as a result of hydrodynamic drag when the legs are being flexed and/or pressed against a solid substrate.

Spider joint hair sensilla: adaptation to proprioreceptive stimulation.

Adding to previous efforts towards a better understanding of the remarkable diversity of spider mechanosensitive hair sensilla, this study examines hairs of Cupiennius salei most likely serving a proprioreceptive function. At the tibia-metatarsus joint of all walking legs, there are two opposing groups of hairs ventrally on the tibia (20 hairs) and metatarsus (75 hairs), respectively. These hairs deflect each other when the joint flexes during locomotion, reversibly interlocking by microtrichs on their hair shafts. The torque resisting the hair deflection into the direction of natural stimulation is smaller by up to two powers of ten than that for the other directions. The torsional restoring constant S of the hair suspension is about 10(-10)Nmrad(-1) in the preferred direction, up to a hair deflection angle of 30° (mean of natural deflection angles). Joint movements were imposed in ranges and at rates measured in walking spiders and sensory action potentials recorded. Within the natural step frequencies (0.3-3Hz) the rate of action potentials follows the velocity of hair deflection. All findings point to the morphological, mechanical, and physiological adaptedness of the joint hair sensilla to their proprioreceptive stimulation during locomotion.

Novel Solution for Leg Motion with 5-Link Belt Mechanism

From the analysis of Theo Jansen walking mechanism and of the path curve that it describes the reduced capability for crossing over obstacles of the Jansen leg (1 DOF) is pointed out. By using a 5 link belt mechanism with 2 DOF can be adapted for generating similar Jansen mechanism path curve, where the step height of this path can be increased. For this purpose a mathematical model is conceived in order to analyse and determine the parameters for driving and control of the operation of the novel walking leg solution.

A new species of Naxia Latreille, 1825 (Brachyura: Majidae) from deep water off Brazil.

A new species of spider crab, Naxia atlantica n. sp., is described and illustrated from deep waters off São Paulo (southeastern Brazil). The new species can be separated from its congeners by a suite of characters including shapes of the propodi of the walking legs, rostrum and basal antennal article. This is the first record of the genus outside southern Australia and New Zealand.

The utility of wax replicas as a measure of crab attack frequency in the rocky intertidal

Crabs are thought to play a vital role in structuring gastropod populations. Studies quantifying the frequencies with which crabs attack gastropods in natural settings are, however, scarce. Although a wide variety of techniques exist with which predator–prey interactions can be investigated (e.g. laboratory experiments, exclusion caging, tethering and population surveys), there is a need for methods that can provide large amounts of quantitative data, particularly documenting the frequency with which crabs attack gastropods. This study examines the utility of using wax replicas of gastropods to determine crab attack frequencies. Replicas ofChlorostoma funebralis, Nucella ostrinaandNucella lamellosawere bolted to mesh screens and deployed in the rocky intertidal. Crabs attacked wax replicas of gastropods, leaving characteristic marks in the wax. In most cases, the appendage used in the attack could be identified from the marks (i.e. chelae vs walking legs). The effectiveness of this technique was verified using surveys of repair scar frequencies of the gastropod populations; patterns in attack frequency, determined from the number of marked wax replicas, were consistent with those of repair frequency, in that both were greater at the wave protected, quiet water locality. This study confirms the value of wax replicas in investigations of crab predation to determine the frequency and type of attack, and illustrates the potential of this method for quantifying predation intensity. The development of techniques that quantify the magnitude and exact nature of the effects of crab predation on intertidal communities is pivotal, given the intensity of commercial fishing of some species of crabs.

Rationale and Design for PACE: Patients with Intermittent Claudication Injected with ALDH Bright Cells

Peripheral artery disease (PAD) is recognized as a public health issue because of its prevalence, functional limitations, and increased risk of systemic ischemic events. Current treatments for claudication, the primary symptom in patients with PAD, have limitations. Cells identified using cytosolic enzyme aldehyde dehydrogenase (ALDH) may benefit patients with severe PAD but has not been studied in patients with claudication. PACE is a randomized, double-blind, placebo-controlled clinical trial conducted by the Cardiovascular Cell Therapy Research Network to assess the safety and efficacy of autologous bone marrow-derived ALDH(br) cells delivered by direct intramuscular injections in 80 patients with symptom-limiting intermittent claudication. Eligible patients will have a significant stenosis or occlusion of infrainguinal arteries and a resting ankle-brachial index less than 0.90 and will be randomized 1:1 to cell or placebo treatment with a 1-year follow-up. The primary end points are the change in peak walking time and leg collateral arterial anatomy, calf muscle blood flow, and tissue perfusion as determined by magnetic resonance imaging at 6 months compared with baseline. The latter 3 measurements are new physiologic lower extremity tissue perfusion and PAD imaging-based end points that may help to quantify the biologic and mechanistic effects of cell therapy. This trial will collect important mechanistic and clinical information on the safety and efficacy of ALDH(br) cells in patients with claudication and provide valuable insight into the utility of advanced magnetic resonance imaging end points.

DEVELOPMENT OF AN AMPHIBIOUS ROBOT FOR VISUAL INSPECTION OF APR1400 NPP IRWST STRAINER ASSEMBLY

An amphibious inspection robot system (hereafter AIROS) is being developed to visually inspect the in-containment refueling storage water tank (hereafter IRWST) strainer in APR1400 instead of a human diver. Four IRWST strainers are located in the IRWST, which is filled with boric acid water. Each strainer has 108 sub-assembly strainer fin modules that should be inspected with the VT-3 method according to Reg. guide 1.82 and the operation manual. AIROS has 6 thrusters for submarine voyage and 4 legs for walking on the top of the strainer. An inverse kinematic algorithm was implemented in the robot controller for exact walking on the top of the IRWST strainer. The IRWST strainer has several top cross braces that are extruded on the top of the strainer, which can be obstacles of walking on the strainer, to maintain the frame of the strainer. Therefore, a robot leg should arrive at the position beside the top cross brace. For this reason, we used an image processing technique to find the top cross brace in the sole camera image. The sole camera image is processed to find the existence of the top cross brace using the cross edge detection algorithm in real time. A 5-DOF robot arm that has multiple camera modules for simultaneous inspection of both sides can penetrate narrow gaps. For intuitive presentation of inspection results and for management of inspection data, inspection images are stored in the control PC with camera angles and positions to synthesize and merge the images. The synthesized images are then mapped in a 3D CAD model of the IRWST strainer with the location information. An IRWST strainer mock-up was fabricated to teach the robot arm scanning and gaiting. It is important to arrive at the designated position for inserting the robot arm into all of the gaps. Exact position control without anchor under the water is not easy. Therefore, we designed the multi leg robot for the role of anchoring and positioning. Quadruped robot design of installing sole cameras was a new approach for the exact and stable position control on the IRWST strainer, unlike a traditional robot for underwater facility inspection. The developed robot will be practically used to enhance the efficiency and reliability of the inspection of nuclear power plant components.

Analysis of Kinematics and Design of Structure Parameters for a Bionic Parallel Leg

This paper proposed a novel bionic walking leg which has three branches of 6-DOF, using 3-UPS parallel mechanism as the prototype, it has good advantage of compact structure and strong bearing capacity. Kinematics research of mechanism is very important, the dynamic analysis and the design are based on kinematics analysis. And the kinematics performance of the bionic walking leg is analyzed and the structure parameters are optimized. First, the kinematics transmission equation of the bionic walking leg is established, and using the norm theory the kinematics performance evaluation indexes are defined, and kinematics characteristics are analyzed. Then, application space model theory the structure parameters of the bionic walking leg are designed, and using of the Monte Carlo parameters selecting method based on the global kinematics performance atlas, the optimal structural parameters are given. Analysis results show that kinematics transmission performance indexes display the symmetric distribution of the bionic walking leg, the static platform radius is 120mm, moving platform radius is 50mm, and the height of the static platform and moving platform initial posture is 700mm. Finally, using the optimal structural size parameters, the virtual prototype of the bionic walking leg is designed. So,it has very important significances of theory and engineering to study and open out parallel mechanisms as the leg mechanisms of bionic walking legs.

Analysis of the Influence of Structure Parameters of Six Degree of Freedom Parallel Robot Workspace

The structure parameters of the robot directly affects its workspace, in order to get the relationship between the structure parameters of the robot and the size of workspace, an evaluation standards of the size of workspace is presented based on the mechanism of the center height. This paper proposes an novel 2URS&UPS parallel robot, it has Six degree of freedom. By using the sphere coordinate searching method, through the MTLAB programming calculated the influence of structural parameters on the workspace. Analysis results show that the parallel robot has the maximum workspace, when the static platform radius is 140mm and the moving platform radius is 120 mm, the rod length is 160mm. The study showed the parallel robot has advantage of a large workspace and symmetry. The parallel robot can be used for walking leg, mechanism arm, etc. The paper provide a theoretical basis for design of the parallel robot.

Ovoviviparous reproduction in Australian specimens of the intertidal isopod Cirolana harfordi

Cirolana harfordi is an intertidal isopod found in the SW Pacific (Eastern Australia: New South Wales and Victoria), NW Pacific (Japan and Russia) and the Pacific coast of North America. C. harfordi from North America has been reported to reproduce by depositing eggs into a marsupial pouch formed by oostegite plates that grow from the base of the 3rd to 6th pereopods (walking legs), so as to incubate embryos and mancas (young that resemble the adult except the seventh pair of pereopods are absent) external to the ventral cuticle of the mother. In this study, however, C. harfordi individuals from New South Wales, Australia were found to incubate embryos and mancas inside the pereon (thorax) cavity. C. harfordi in Australia is, therefore, displaying ovoviviparous reproduction and not incubation in a marsupial pouch external to the pereon as previously thought. Embryos have a direct development pathway to the internal manca stage that is held within the mother’s body cavity until the time of live birth. Additionally, internal mancas show some morphological differences to adults, such as a lack of cusps on the mandibles.

Egg mass ventilation by caridean shrimp: similarities to other decapods and insight into pheromone receptor location

Egg clutch brooding and larval release behaviour are common among decapods and involve pheromone communication between the developing embryos and the brooding female. We tested caridean shrimps to determine whether their behaviour was similar to other decapods. In tests with aqueous extracts of crushed eggs and peptide pheromone mimic shrimps responded similarly to brachyurans and lobsters. The elongate body form of shrimps enabled us to focally stimulate body locations with the goal of determining the location of pheromone receptors. The receptors for the pheromones are likely located on the bases of the walking legs or on the gills, not on the pleopods, first walking legs, antennae or antennules. Shrimps are another example of organisms that use peptides generated by trypsin-like serine proteases as pheromones and signal molecules.

The Red Sea species of Cymo de Haan, 1833 (Decapoda, Brachyura, Xanthidae), associates of scleractinian corals.

Four species of Cymo, associates of scleractinian corals, from the Red Sea were studied using scanning electron and light microscopy. Characters based on the morphologies of the carapace, gonopods and digestive tract (gastric teeth) were investigated and described in detail. All Red Sea species are redescribed, distinguishing characters are identified and an identification key is provided. Cymo quadrilobatus is the most distinctive species, with prominent granules on the carapace and most of the surfaces of the chelipeds and walking legs, and four red spots on the dorsal surface of the carapace in contrast to the smooth or finely granular surfaces in the other three species. Cymo deplanatus is listed as new record for the Red Sea.

Objective measurement of lower extremity function and quality of life after surgical revascularization for critical lower extremity ischemia

Outcomes of revascularization for critical limb ischemia (CLI) have historically been patency, limb salvage, and survival. Functional status and quality of life have not been well described. This study used functional and quality of life assessments to measure patient-centered outcomes after revascularization for CLI. The study observed 18 patients (age, 65± 11years) prospectively before and after lower extremity bypass for CLI. Patients completed the Short Physical Performance Battery, which measures walking speed, leg strength, and balance, as well as performed a 6-minute walk, and calorie expenditure was measured by an accelerometer. Isometric muscle strength was assessed with the Muscle Function Evaluation chair (Metitur, Helsinki, Finland). Quality of life instruments included the 36-Item Short Form Health Survey and the Vascular Quality of Life questionnaire. Patients' preoperative status was compared with 4-month postoperative status. Muscle Function Evaluation chair measurements of ipsilateral leg strength demonstrated a significant increase in knee flexion from 64± 62N to 135± 133N (P= .038) and nearly significant increase in knee extension from 120± 110N to 186± 85N (P= .062) and ankle plantar flexion from 178± 126N to 267± 252N (P= .078). In the contralateral leg, knee flexion increased from 71± 96N to 149± 162N (P= .028) and knee extension from 162± 112N to 239± 158N (P= .036). Absolute improvements were noted in 6-minute walk distance, daily calorie expenditure, and individual domains and overall Short Physical Performance Battery scores, and upper extremity strength decreased, although none were significant. The Vascular Quality of Life questionnaire captured significant improvement in all individual domains and overall score (P< .015). Significant improvement was noted only for bodily pain (P= .011) on the 36-Item Short Form Health Survey. Despite lack of statistical improvement in most functional test results, revascularization for CLI results in improved patient-perceived leg function. Significant improvements in isometric muscle strength may explain the measured improvement in quality of life after revascularization for CLI.

Energetic and Peak Power Advantages of Series Elastic Actuators in an Actuated Prosthetic Leg for Walking and Running

A monoarticular series elastic actuator (SEA) reduces energetic and peak power requirements compared to a direct drive (DD) in active prosthetic ankle-foot design. Simulation studies have shown that similar advantages are possible for the knee joint. The aims of this paper were to investigate the advantages of a monoarticular SEA-driven hip joint and to quantify the energetic benefit of an SEA-driven leg (with monoarticular hip, knee and ankle SEAs), assuming that damping (negative power) is passively achieved. The hip SEA provided minor energetic advantages in walking (up to 29%) compared to the knee and the ankle SEA. Reductions in required peak power were observed only for speeds close to preferred walking speed (18% to 27%). No energetic advantages were found in running, where a DD achieved the best performance when optimizing for energy. Using an SEA at each leg joint in the sagittal plane reduced the positive work by 14% to 39% for walking and by 37% to 75% for running. When using an SEA instead of a DD, the contribution of the three leg joints to doing positive work changed: the knee contributed less and the hip more positive work. For monoarticular SEAs, the ankle joint motor did most of the positive work.

Squat lobsters (Crustacea: Anomura) from Mauritanian waters (West Africa), with the description of a new species of Munidopsis.

This paper is the result of the study of a squat lobsters collection obtained along the Mauritanian coast, between 91 and 1867 m depth, during the 'MAURIT' surveys carried out in the period from 2007 to 2010. Eumunida bella de Saint Laurent & Macpherson, 1990 (Chirostyloidea) and six species of Munida and Munidopsis (Galatheoidea) are reported in the present work.A new species, Munidopsis anaramosae n. sp. collected off northwestern Banc d'Arguin at 1000-1012 m depth, is described and illustrated. The presence of an eyespine that arises distally from the middle end of the cornea, walking legs merus spinose on dorsal and ventral margins and cheliped merus ventrally unarmed distinguish it from related species. Munida chunii Balss, 1913 is redescribed here and the new records of Munida guineae Miyake & Baba, 1970, M. speciosa von Martens, 1878 and Munidopsis chunii Balss, 1913 extend their geographical distribution northwards, and in the case of the last species, increase its bathymetric range.

Mortality and deformities in European lobster (Homarus gammarus) juveniles exposed to the anti-parasitic drug teflubenzuron

This study describes experiments carried out to examine effects of the antiparasitic drug teflubenzuron, used in delousing farmed salmon, on a non-target species, the European lobster (Homarus gammarus). Juvenile lobsters were fed two doses of teflubenzuron, 10 and 20mg/kg successively for 7 days corresponding to a standard medication of the fish (10mg/kg day) and twice the standard dose (20mg/kg day). Monitoring lasted 3 months to include at least one moulting period for all individuals. Cumulative mortality was higher in all replicates given medicated feed compared with the control group. Mean cumulative mortality for each dosing was 41±13% for 10mg/kg and 38±8% for 20mg/kg, i.e. no difference. Drug residue was analysed in all juveniles that died, in addition to 12 juveniles at day 8 and the first 12 surviving lobsters. A decline in concentration of teflubenzuron from over 8000ng/g (day 5) to 14ng/g (day 70) was observed in the juveniles that died during the experiment. Twelve individuals that died contained 82ng/g or less whereas the mean concentration in the first 12 lobsters that survived moulting was 152ng/g. Following a single oral administration, the half-life of teflubenzuron in lobster was estimated to 3.4 days and the initial concentration (C0) to 515ng/g at time t0. At the end of the study a considerable number of juvenile lobsters were observed with deformities in various organs; carapace, walking legs, cheliped, tail fan, abdomen and antenna. The occurrence of observed deformities varied from 0 to 15% in treated replicates and will most likely affect ability to locate and consume food (antenna, claw and walking legs), respiration (carapace) and ability to move/swim (walking legs, tail fan and abdomen). In total, the mortality and senescent damages were close to 50% in all replicates. Juveniles that survived medication without deformities however, moulted and increased in size at each moult equally well as the unmedicated controls.

Proximate Composition and Mineral Contents of Freshwater Crab Spiralothelphusa hydrodroma (Herbst, 1794) from Parangipettai, South East Coast of India

The role of aquatic rice field species in rural diets has been underestimated. These aquatic animals potentially supply most of the protein, carbohydrate and other nutrients that are needed by the villagers. The information on nutritional composition of aquatic animal resources from rice fields is scarce since they are not common in the food baskets of most other countries. Generally marine crabs are widely used as food and feed supplements throughout the world, but people do not consider paddy fields for freshwater crabs. Although large numbers of freshwater crabs are suitable for human consumption, these aquatic animals are not consumed in large quantities elsewhere. National and regional food composition data bases contain very limited info on nutritional composition of these species. In the present study an attempt has been made to evaluate the nutritional status of the edible potamid crab The result showed that the parameters like protein, carbohydrate, lipid, moisture and ash and minerals of calcium, magnesium, potassium, sodium, iron, copper and zinc were maximum in cephalothorax and minimum in swimming and walking legs.

Segmentation of the millipede trunk as suggested by a homeotic mutant with six extra pairs of gonopods

BackgroundThe mismatch between dorsal and ventral trunk features along the millipede trunk was long a subject of controversy, largely resting on alternative interpretations of segmentation. Most models of arthropod segmentation presuppose a strict sequential antero-posterior specification of trunk segments, whereas alternative models involve the early delineation of a limited number of ‘primary segments’ followed by their sequential stereotypic subdivision into 2n definitive segments. The ‘primary segments’ should be intended as units identified by molecular markers, rather than as overt morphological entities. Two predictions were suggested to test the plausibility of multiple-duplication models of segmentation: first, a specific pattern of evolvability of segment number in those arthropod clades in which segment number is not fixed (e.g., epimorphic centipedes and millipedes); second, the occurrence of discrete multisegmental patterns due to early, initially contiguous positional markers.ResultsWe describe a unique case of a homeotic millipede with 6 extra pairs of ectopic gonopods replacing walking legs on rings 8 (leg-pairs 10-11), 15 (leg-pairs 24-25) and 16 (leg-pairs 26-27); we discuss the segmental distribution of these appendages in the framework of alternative models of segmentation and present an interpretation of the origin of the distribution of the additional gonopods.The anterior set of contiguous gonopods (those normally occurring on ring 7 plus the first set of ectopic ones on ring 8) is reiterated by the posterior set (on rings 15-16) after exactly 16 leg positions along the AP body axis. This suggests that a body section including 16 leg pairs could be a module deriving from 4 cycles of regular binary splitting of an embryonic ‘primary segment’.ConclusionsA very likely early determination of the sites of the future metamorphosis of walking legs into gonopods and a segmentation process according to the multiplicative model may provide a detailed explanation for the distribution of the extra gonopods in the homeotic specimen. The hypothesized steps of segmentation are similar in both a normal and the studied homeotic specimen. The difference between them would consist in the size of the embryonic trunk region endowed with a positional marker whose presence will later determine the replacement of walking legs by gonopods.

Nonparetic knee extensor strength is the determinant of exercise capacity of community-dwelling stroke survivors.

Objective. To investigate the relationship among walking speed, exercise capacity, and leg strength in community dwelling stroke subjects and to evaluate which one was the leading determinant factor of them. Design. This is a descriptive, cross-sectional study. Thirty-five chronic stroke patients who were able to walk independently in their community were enrolled. Walking speed was evaluated by using the 12-meter walking test. A maximal exercise test was used to determine the stroke subjects' exercise capacity. Knee extensor strength, measured as isokinetic torque, was assessed by isokinetic dynamometer. Results. The main walking speed of our subjects was 0.52 m/s. Peak oxygen uptake (VO2 peak) was 1.21 ± 0.43 L/min. Knee extensor strength, no matter whether paretic or nonparetic side, was significantly correlated to 12-meter walking speed and exercise capacity. Linear regression also showed the strength of the affected knee extensor was the determinant of walking speed and that of the nonparetic knee extensor was the determinant of exercise capacity in community dwelling stroke subjects. Conclusions. Walking speed and peak oxygen uptake were markedly decreased after stroke. Knee extensor strength of nonparetic leg was the most important determinant of exercise capacity of the community-dwelling stroke subjects. Knee extensor strengthening should be emphasized to help stroke patient to achieve optimal community living.

The Hox genes Ultrabithorax and abdominal-A specify three different types of abdominalappendage in the springtail Orchesella cincta (Collembola)

BackgroundIn Drosophila and many other insects, the Hox genes Ultrabithorax (Ubx) and abdominal-A (abd-A) suppress limb formation on most or all segments of the abdomen. However, a number of basal hexapod lineages retain multiple appendages on the abdomen. In the collembolans or springtails, three abdominal segments develop specialized organs that originate from paired appendage primordia which fuse at the midline: the first abdominal segment bears the collophore (ventral tube), involved in osmoregulation; the fourth segment bears the furca, the leaping organ, and the third segment bears the retinaculum, which retains the furca at rest. Ubx and abd-A are known to be expressed in the springtail abdomen, but what role they play in specifying these distinct abdominal appendages is not known. This is largely because no genetic model has been established in collembolans or any other non-insect hexapod.ResultsWe have developed a convenient method for laboratory culture of the collembolan Orchesella cincta on defined media, a method for in-situ hybridization to embryos and a procedure for gene knockdown by parental injection of double-stranded RNA (RNAi). We show that Orchesella Ubx transcripts are detectable in the first to third abdominal segments, and abd-A transcripts in the second to fourth segments. Knockdown of Oc-Ubx leads to the homeotic transformation of the collophore into a pair of walking legs (a more anterior identity) but the retinaculum into a furca (a more posterior identity). Knockdown of Oc-abd-A leads to the transformation of the retinaculum into a collophore and of the furca into legs (both anterior transformations). Simultaneous silencing of both Oc-Ubx and Oc-abd-A transformed all three of these appendages into paired legs, but did not cause appendages to develop on the second, or on the most posterior abdominal segments.ConclusionsWe conclude that, in Orchesella, Oc-Ubx alone specifies the collophore on the first and Oc-abd-A alone specifies the furca on the fourth abdominal segment. Oc-Ubx and Oc-abd-A function together, apparently combinatorially, to specify the retinaculum on the third segment. The efficiency of RNAi in Orchesella makes this an attractive model for further genetic studies of development and physiology in basal hexapods.Electronic supplementary materialThe online version of this article (doi:10.1186/2041-9139-5-2) contains supplementary material, which is available to authorized users.