scholarly journals A general model of locomotion of brittle stars with a variable number of arms

2020 ◽  
Vol 17 (162) ◽  
pp. 20190374 ◽  
Author(s):  
Daiki Wakita ◽  
Katsushi Kagaya ◽  
Hitoshi Aonuma
Keyword(s):  
Arm Movement ◽  
Single Species ◽  
Statistical Modelling ◽  
Variable Number ◽  
Fixed Number ◽  
The Body ◽  
Brittle Stars ◽  
Decentralized System ◽  
Symmetrical Body ◽  
Left And Right

Typical brittle stars have five radially symmetrical arms that coordinate to move the body in a certain direction. However, some species have a variable number of arms, which is a unique trait since intact animals normally have a fixed number of limbs. How does a single species manage different numbers of appendages for adaptive locomotion? We herein describe locomotion in Ophiactis brachyaspis with four, five, six and seven arms to propose a common rule for the movement of brittle stars with different numbers of arms. For this, we mechanically stimulated one arm of individuals to analyse escape direction and arm movement. By gathering quantitative indices and employing Bayesian statistical modelling, we noted a pattern: regardless of the total number of arms, an anterior position emerges at one of the second neighbouring arms to a mechanically stimulated arm, while arms adjacent to the anterior one synchronously work as left and right rowers. We propose a model in which an afferent signal runs clockwise or anticlockwise along the nerve ring while linearly counting how many arms it passes through. With this model, the question on how ‘left and right’ emerges in a radially symmetrical body via a decentralized system is answered.

scholarly journals Generalized locomotion of brittle stars with a flexible number of arms

2019 ◽  
Author(s):  
Daiki Wakita ◽  
Katsushi Kagaya ◽  
Hitoshi Aonuma
Keyword(s):  
Single Species ◽  
Fixed Number ◽  
Nerve Ring ◽  
Brittle Stars ◽  
Decentralized System ◽  
Quantitative Indices ◽  
Front Position ◽  
Symmetrical Body ◽  
Left And Right ◽  
Bayesian Statistical Modeling

AbstractTypical brittle stars have five radially symmetrical arms, which coordinate to move their body in a certain direction. However, some species of them show individual difference in the number of arms. We found this trait unique since intact legged animals each own a fixed number of limbs in general. How does a single species manage such different numbers of motile organs to realize adaptive locomotion? We here described four-, five-, six-, and seven-armed locomotion with the aim to generalize a common rule which is flexible with arm numbers in brittle stars. We mechanically stimulated an arm inOphiactis brachyaspisto analyze escape direction and arm movements. Gathering quantitative indices and employing Bayesian statistical modeling, we figured out an average locomotion: regardless of the total number of arms, a front position emerges at one of the second neighboring arms to a mechanically stimulated arm, while side arms adjacent to the front synchronously work as left and right rowers. We suggest a model where some afferent signal runs either clockwise or anticlockwise along the nerve ring while linearly counting how many arms it passes. This idea would explain how ‘left and right’ emerges in a radially symmetrical body via a decentralized system.

Electromyographic Evaluation of Arm and Torso Muscles for Different Postures in Windsurfing

1988 ◽  
Vol 4 (2) ◽  
pp. 156-165 ◽  
Author(s):  
Bart Van Gheluwe ◽  
Paul Huybrechts ◽  
Erik Deporte
Keyword(s):  
Muscle Activation ◽  
Muscular Activity ◽  
The Body ◽  
Erector Spinae ◽  
Electromyographic Activity ◽  
Skill Levels ◽  
Flexor Carpi Radialis ◽  
Symmetrical Body ◽  
Left And Right ◽  
Low Activity

This study evaluates the action of 20 selected arm and torso muscles. The subjects were 19 windsurfers of different skill levels. Muscular activity was recorded electromyographically, using surface electrodes. The subjects were standing on a specially devised windsurf simulator in order to keep the different surf postures as standardized as possible. Through two-way ANOVA techniques, the electromyographic activity relative to its maximal isometric value was compared for different muscles, surf postures, and skill levels. Also, differences between the left and right sides of the body were investigated. From the results, the following may be concluded: (a) As all muscles display rather low activity (an average of less than 20% of their maximal isometric values), windsurfing does not seem very demanding of muscular force. (b) The M. flexor carpi radialis, together with the M. erector spinae, tend to exhibit higher levels of activity for beginners, which suggests, respectively, a more rigid grip on the wishbone and stronger low back muscle activation in order to keep a correct posture, (c) Left–right asymmetries mainly occur for symmetrical body postures, especially for the M. flexor carpi radialis and the M. erector spinae. As for the M. trapezius (pars superior), experienced surfers tend to display a dominant right asymmetry, (d) Muscle activity does not exhibit significantly different values for various surf postures. However, typical deviating postures, as observed in beginners, may induce higher levels of muscle activation.

Concluding remarks

1956 ◽  
Vol 146 (922) ◽  
pp. 90-92 ◽  
Keyword(s):  
Guinea Pigs ◽  
Current Trend ◽  
Distinct Type ◽  
Single Species ◽  
Immunological Tolerance ◽  
The Body ◽  
Immunological Reaction ◽  
Picryl Chloride ◽  
Purified Antigen ◽  
Circulating Antibody

In many ways immunological tolerance is an ideal subject for discussion at the present time. Experimental work has gone far enough to allow us to claim that the principle of immunological tolerance is soundly established and that we can see more or less clearly some of its implications. But obviously very much remains to be learnt of the part played by tolerance in the various fields that have been discussed. It is by no means certain that we are dealing with a single topic when we compare tolerance to homografts with inhibition of antibody production against soluble protein in a rabbit. Such a situation provides much for discussion but does not make it easy to condense or interpret that discussion. One might begin by reiterating that immunology is concerned with much more than the production and properties of typical circulating antibody. There are at least four different types of immunological reaction and there are hints of many minor differences within the main types. Pappenheimer’s recent work on the variety of responses given by a single species, man, to a single purified antigen, diphtheria toxoid, offers a characteristic example of the current trend. Chase’s experiments on the response of guinea pigs to simple allergens like picryl chloride, have been only incidentally mentioned in today’s discussion, but their importance is obvious. A form of tolerance very similar to that produced by prenatal treatment of mice can be produced by administering the allergen to adult guinea-pigs by mouth. The animals are resistant to sensitization by skin treatment and the inhibition is general and unrelated to any persistence of allergen in the body. The question immediately arises whether all forms of tolerance are basically similar or whether for each of the qualitatively distinct types of positive immunological reaction, a correspondingly distinct type of inhibition or tolerance must be sought.

XIX. On the structure and development of myriothela

1875 ◽  
Vol 165 ◽  
pp. 549-575 ◽  
Keyword(s):  
Single Species ◽  
The Body ◽  
Entire Length ◽  
Species Being

Mykiothela, of which we have as yet no satisfactory evidence of more than a single species being known, consists of a solitary attached hydranth, carrying near its proximal or attached end the blastostyles or appendages which give origin and support to the gonophores (Plate 55). Full-sized specimens (fig. 1) measure, when extended, nearly 2 inches in length. They are then cylindrical in form, with the mouth occupying the summit of a short conical hypostome, behind which the tentacles commence, and thence extend over somewhat more than one half the entire length of the body; while the proximal end of the body is bent at right angles to the rest, is invested with a chitinous perisarc, and gives origin to short sucker-like processes of attachment.

scholarly journals Study of Second and Fourth Digit Lengths and Their Ratios With Physical Attributes in Nepali Population

2018 ◽  
Vol 16 (2) ◽  
pp. 78-81
Author(s):  
Biswas Satyal ◽  
Abhishek Satyal
Keyword(s):  
Ring Finger ◽  
The Body ◽  
Behavioral Traits ◽  
Digit Ratios ◽  
Hand Deformities ◽  
Significant Difference ◽  
Physical Attributes ◽  
Physical Traits ◽  
Left And Right ◽  
Males And Females

Introduction: The ratio of the lengths of the index and the ring finger (2D:4D ratio) is generally different between men and women. A number of studies have shown a correlation between the 2D:4D digit ratio and various physical and behavioral traits. The aim of the present study is to investigate the association of the index (2nd) and ring (4th) digit ratios with some physical traits in Nepal population. Material & Method: 200 students (100 males and 100 females) between ages of 18 years and above were randomly selected with exclusion of those with hand deformities. The digit lengths were measured from the basal crease to the tips usingvernier calipers. The 2D:4D ratios were determined for each subject while height and weight were used to calculate the body mass index and data analyzed. The study was conducted between January 2018 to November 2018. Result: The result of the anthropometric study of the differences in index (2D) and ring (4D) and their ratios shows that there was a significant difference between the length of index finger (2D), ring finger (4D) and the ratios of right hand's 2D:4D in both males and females. There was appositive correlation between the second digit length and Height and weight in males and females both on right and left sides. The 2D:4D ratio for both left and right hand did not show any positive correlation with height, weight or BMI of an individual.

scholarly journals Standard reference values of weight and maximum pressure distribution in healthy adults aged 18–65 years in Germany

2020 ◽  
Vol 39 (1) ◽  
Author(s):  
D. Ohlendorf ◽  
K. Kerth ◽  
W. Osiander ◽  
F. Holzgreve ◽  
L. Fraeulin ◽  
...  
Keyword(s):  
Body Weight ◽  
Pressure Distribution ◽  
Reference Values ◽  
Effect Size ◽  
Weight Distribution ◽  
Age Groups ◽  
Healthy Adults ◽  
The Body ◽  
Maximum Pressure ◽  
Left And Right

Abstract Background The aim of this study was to collect standard reference values of the weight and the maximum pressure distribution in healthy adults aged 18–65 years and to investigate the influence of constitutional parameters on it. Methods A total of 416 healthy subjects (208 male / 208 female) aged between 18 and 65 years (Ø 38.3 ± 14.1 years) participated in this study, conducted 2015–2019 in Heidelberg. The age-specific evaluation is based on 4 age groups (G1, 18–30 years; G2, 31–40 years; G3, 41–50 years; G4, 51–65 years). A pressure measuring plate FDM-S (Zebris/Isny/Germany) was used to collect body weight distribution and maximum pressure distribution of the right and left foot and left and right forefoot/rearfoot, respectively. Results Body weight distribution of the left (50.07%) and right (50.12%) foot was balanced. There was higher load on the rearfoot (left 54.14%; right 55.09%) than on the forefoot (left 45.49%; right 44.26%). The pressure in the rearfoot was higher than in the forefoot (rearfoot left 9.60 N/cm2, rearfoot right 9.51 N/cm2/forefoot left 8.23 N/cm2, forefoot right 8.59 N/cm2). With increasing age, the load in the left foot shifted from the rearfoot to the forefoot as well as the maximum pressure (p ≤ 0.02 and 0.03; poor effect size). With increasing BMI, the body weight shifted to the left and right rearfoot (p ≤ 0.001, poor effect size). As BMI increased, so did the maximum pressure in all areas (p ≤ 0.001 and 0.03, weak to moderate effect size). There were significant differences in weight and maximum pressure distribution in the forefoot and rearfoot in the different age groups, especially between younger (18–40 years) and older (41–65 years) subjects. Discussion Healthy individuals aged from 18 to 65 years were found to have a balanced weight distribution in an aspect ratio, with a 20% greater load of the rearfoot. Age and BMI were found to be influencing factors of the weight and maximum pressure distribution, especially between younger and elder subjects. The collected standard reference values allow comparisons with other studies and can serve as a guideline in clinical practice and scientific studies.

scholarly journals Morphology and sexual dimorphism of living mature adults of Amphiduros fuscescens (Marenzeller, 1875) (Annelida, Hesionidae, Amphidurine), first reported for the Iberian Peninsula

2021 ◽  
Vol 9 ◽  
Author(s):  
Daniel Martin ◽  
Chiara Romano
Keyword(s):  
Sexual Dimorphism ◽  
Iberian Peninsula ◽  
Taxonomic Status ◽  
Single Species ◽  
First Record ◽  
The Body ◽  
Valid Species ◽  
Mature Adults ◽  
Nw Mediterranean ◽  
Cryptic Species Complex

To date, the genus Amphiduros (Annelida: Hesionidae: Amphidurine) is considered as monotypic. Its single species, Amphiduros fuscescens (Marenzeller, 1875), is well characterised by lacking proboscideal papillae and emerging acicular chaetae, as well as by having three antennae, eight pairs of tentacular cirri and inflated dorsal cirri with characteristic alternating length and colour (transparent, with median orange band and white tips) in live animals. Three specimens, one male and two females, were found below boulders at 5–7 m depth in Punta Santa Anna, Blanes and Cala Maset, Sant Feliu de Guixols (Catalan Sea, NW Mediterranean, Iberian Peninsula). Our finding allowed us to describe different, unreported morphological traits and lead us to support the existence of sexual dimorphism (in terms of colouring, cirri morphology and distribution of sexual products along the body). Despite A. fuscescens having been previously reported from the Atlantic and the Mediterranean (particularly in SE French coasts), the specimens from Blanes represent the first record of the species from the Iberian Peninsula. In addition, our molecular results strongly support that Amphiduros pacificus Hartman, 1961 from California (currently synonymised with A. fuscescens) requires to be re-described and reinstalled as a valid species. In turn, our morphological observations support suggesting all other non-Mediterranean reports of A. fuscescens, including the species still under synonymy (i.e. Amphidrornus izukai Hessle, 1925 and Amphidromus setosus Hessle, 1925) as likely being a cryptic species complex whose the taxonomic status requires further assessment.

Coordination of locomotor and cardiorespiratory networks of Lymnaea stagnalis by a pair of identified interneurones

1991 ◽  
Vol 158 (1) ◽  
pp. 37-62 ◽  
Author(s):  
N. I. Syed ◽  
W. Winlow
Keyword(s):  
Body Wall ◽  
Lymnaea Stagnalis ◽  
The Body ◽  
Whole Body ◽  
Pond Snail ◽  
Selective Ablation ◽  
The Central Nervous System ◽  
Body Wall Muscles ◽  
Bilateral Pair ◽  
Left And Right

1. The morphology and electrophysiology of a newly identified bilateral pair of interneurones in the central nervous system of the pulmonate pond snail Lymnaea stagnalis is described. 2. These interneurones, identified as left and right pedal dorsal 11 (L/RPeD11), are electrically coupled to each other as well as to a large number of foot and body wall motoneurones, forming a fast-acting neural network which coordinates the activities of foot and body wall muscles. 3. The left and right sides of the body wall of Lymnaea are innervated by left and right cerebral A cluster neurones. Although these motoneurones have only ipsilateral projections, they are indirectly electrically coupled to their contralateral homologues via their connections with L/RPeD11. Similarly, the activities of left and right pedal G cluster neurones, which are known to be involved in locomotion, are also coordinated by L/RPeD11. 4. Selective ablation of both neurones PeD11 results in the loss of coordination between the bilateral cerebral A clusters. 5. Interneurones L/RPeD11 are multifunctional. In addition to coordinating motoneuronal activity, they make chemical excitatory connections with heart motoneurones. They also synapse upon respiratory motoneurones, hyperpolarizing those involved in pneumostome opening (expiration) and depolarizing those involved in pneumostome closure (inspiration). 6. An identified respiratory interneurone involved in pneumostome closure (visceral dorsal 4) inhibits L/RPeD11 together with all their electrically coupled follower cells. 7. Both L/RPeD11 have strong excitatory effects on another pair of electrically coupled neurones, visceral dorsal 1 and right parietal dorsal 2, which have previously been shown to be sensitive to changes in the partial pressure of environmental oxygen (PO2). 8. Although L/RPeD11 participate in whole-body withdrawal responses, electrical stimulation applied directly to these neurones was not sufficient to induce this behaviour.

Coding Body Language in Sports: The Nonverbal Behavior Coding System for Soccer Penalties

2020 ◽  
pp. 1-15
Author(s):  
Philip Furley ◽  
Alexander Roth
Keyword(s):  
Nonverbal Behavior ◽  
Arm Movement ◽  
Emotional Valence ◽  
The Body ◽  
Emotional States ◽  
Coding System ◽  
Temporal Precision ◽  
Intercoder Reliability ◽  
Coding Schemes ◽  
Behavior Coding

Nonverbal behavior (NVB) plays an important role in sports. However, it has been difficult to measure, as no coding schemes exist to objectively measure NVB in sports. Therefore, the authors adapted the Body Action and Posture Coding System to the context of soccer penalties, validated it, and initially used this system (Nonverbal Behavior Coding System for Soccer Penalties [NBCSP]) to explore NVB in penalties. Study 1 demonstrated that the NBCSP had good to excellent intercoder reliability regarding the occurrence and temporal precision of NVBs. It also showed that the coding system could differentiate certain postures and behaviors as a function of emotional valence (i.e., positive vs. negative emotional states). Study 2 identified differences in NVB for successful and missed shots in a sample of penalties (time spent looking toward the goal, toward the ground, right arm movement, and how upright the body posture was). The authors discuss the utility of the coding system for different sport contexts.

scholarly journals Acoustic information about upper limb movement in voicing

2020 ◽  
Vol 117 (21) ◽  
pp. 11364-11367 ◽  
Author(s):  
Wim Pouw ◽  
Alexandra Paxton ◽  
Steven J. Harrison ◽  
James A. Dixon
Keyword(s):  
Steady State ◽  
Upper Limb ◽  
Arm Movement ◽  
Limb Movement ◽  
Interpersonal Perception ◽  
The Body ◽  
Acoustic Information ◽  
Human Voice ◽  
Vocal System ◽  
The Voice

We show that the human voice has complex acoustic qualities that are directly coupled to peripheral musculoskeletal tensioning of the body, such as subtle wrist movements. In this study, human vocalizers produced a steady-state vocalization while rhythmically moving the wrist or the arm at different tempos. Although listeners could only hear and not see the vocalizer, they were able to completely synchronize their own rhythmic wrist or arm movement with the movement of the vocalizer which they perceived in the voice acoustics. This study corroborates recent evidence suggesting that the human voice is constrained by bodily tensioning affecting the respiratory–vocal system. The current results show that the human voice contains a bodily imprint that is directly informative for the interpersonal perception of another’s dynamic physical states.

Sign in / Sign up

Export Citation Format

Share Document