Behavioural responses of the cercariae of Cryptocotyle lingua (Digenea: Heterophyidae) to computer-controlled shadow sequences

Parasitology ◽  
1991 ◽  
Vol 103 (3) ◽  
pp. 471-477 ◽  
Author(s):  
J. G. Rea ◽  
S. W. B. Irwin
Keyword(s):  
Laboratory Experiments ◽  
Muscular Activity ◽  
Finite Energy ◽  
Fish Host ◽  
Activity Levels ◽  
Energy Reserves ◽  
Population Activity ◽  
Behavioural Responses ◽  
Active Life ◽  
Computer Controlled

The cercariae of Cryptocotyle lingua have a brief but active life during which they do not feed. In order to maximize the probability of infection they must respond to a variety of host-related stimuli yet conserve their finite energy reserves by minimizing unnecessary muscular activity. In laboratory experiments, simulated shadows representing the passage of a fish host were found to increase population activity levels. Evidence was also found for a relationship between shadow duration and the duration of subsequent bursts of swimming activity. Adaptation to continuous shadowing was recorded, its onset and magnitude being dependent on both the frequency and duration of shadows delivered. As cercariae aged they became less responsive to shadow stimuli, especially those of short duration.

The effects of age, temperature, light quantity and wavelength on the swimming behaviour of the cercariae of Cryptocotyle lingua (Digenea: Heterophyidae)

Parasitology ◽  
1992 ◽  
Vol 105 (1) ◽  
pp. 131-137 ◽  
Author(s):  
J. G. Rea ◽  
S. W. B. Irwin
Keyword(s):  
Life Span ◽  
Water Temperature ◽  
Light Source ◽  
Laboratory Experiments ◽  
Temperature Dependent ◽  
Release Point ◽  
Successful Transmission ◽  
Active Life ◽  
Light Quantity ◽  
Precipitous Decline

Laboratory experiments indicated that the active life-span of the cercariae of Cryptocotyle lingua was temperature-dependent. An increase in water temperature and population age both correlated with a tendency for the organisms to become decaudate. The larvae were strongly photoresponsive to lateral light but with time, horizontal swimming rates (HSRs) from release point to light source progressively declined. When measured over a range of light quantities, HSRs peaked at 30 μM/m2/s. HSRs were also influenced by water temperature. A rapid increase occurred up to 15 °C after which there was a precipitous decline. HSRs to coloured light were negatively correlated with increasing wavelength. When offered a choice between colours, cercariae favoured the shorter wavelengths. The implications of these responses for successful transmission are discussed.

Bone Elastometric Measurements by Ultrasound Reflectometry: Observations on Physiology and Functional Organization of Bone

2000 ◽  
Author(s):  
Shreefal S. Mehta ◽  
Peter P. Antich ◽  
Billy Smith ◽  
Matthew A. Lewis ◽  
Edmond Richer
Keyword(s):  
Mechanical Properties ◽  
Functional Organization ◽  
Muscular Activity ◽  
Diagnostic Techniques ◽  
Rate Of Change ◽  
Activity Levels ◽  
Bone Material ◽  
Clinical Observations ◽  
First Time

Abstract Bone mechanical properties are strongly dependent on orientation and optimally adapted to the directional stresses induced by load bearing and muscular activity. Spatial and directional homogeneity and a slow rate of change of material mechanical properties are commonly assumed in the literature. The assumptions are based on limitations of widespread diagnostic techniques but are contradicted by results from several established techniques, including ultrasound reflectometry. A device based on the ultrasound reflectometry technique measures the mechanical elasticity of bone noninvasively at multiple sites and orientations, making it possible to carry out longitudinal studies at any chosen location in vivo. In vivo elastometric measurements over the length of a tibia were obtained with this device, demonstrating quantitatively for the first time the spatial and directional heterogeneity of bone material properties in vivo. Clinical observations made on two subjects also suggest that bone does exhibit rapid changes in response to altered activity levels.

Head Movements and Neck Muscle Activity During Air Combat Maneuvering

2020 ◽  
Vol 91 (1) ◽  
pp. 26-31 ◽  
Author(s):  
Roope Sovelius ◽  
Maunu Mäntylä ◽  
Heini Huhtala ◽  
Juha Oksa ◽  
Rasmus Valtonen ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Muscular Activity ◽  
Head Movements ◽  
Neck Muscle ◽  
Activity Levels ◽  
Sitting Posture ◽  
Field Of Vision ◽  
Air Combat ◽  
The Difference ◽  
Neutral Posture

BACKGROUND: The aim of the study was to determine the characteristics of cervical muscle activity in different head movements when using helmet mounted display in air combat maneuvering.METHODS: Cervical EMG was measured with eight F/A-18 pilots using the Joint Helmet Mounted Cueing System (JHMCS) during air combat maneuvering. In-flight Gz acceleration and continuous head position were recorded. Muscular activity was compared between head movements in isolation and combined with torso movement. In addition, the effect of the direction of head movements and the use of head support of the ejection seat on muscle activity was determined.RESULTS: Muscular loading increased in the cervical flexors and extensors when using the torso during targeting beyond the field of vision in the neutral sitting posture; the difference was significant in the flexors, but activity levels were higher in the extensors. Cervical muscles are loaded to a lesser extent if the head is kept in a stable position during Gz loading. Muscular activity in the neck muscles was higher when the pilot was moving the head out of neutral posture rather than toward neutral posture. The use of the headrest as a support decreased muscle activity in the extensors, but resulted in higher activity in the flexor muscles.DISCUSSION: All analyzed conditions were significantly affected by an increase in Gz. An increase of muscle activity with torso movements is considered as a positive factor as it reflects maintained muscular support for the cervical spine. Presented results may be helpful when specific conditioning programs and cockpit ergonomics are developed for fighter pilots.Sovelius R, Mäntylä M, Huhtala H, Oksa J, Valtonen R, Tiitola L, Leino T. Head movements and neck muscle activity during air combat maneuvering. Aerosp Med Hum Perform. 2020; 91(1):26–31.

Desiccation tolerance of dauers of entomopathogenic nematodes of the genus Steinernema

Nematology ◽  
2013 ◽  
Vol 15 (4) ◽  
pp. 451-458 ◽  
Author(s):  
Prakaijan Nimkingrat ◽  
Felix Uhlmann ◽  
Olaf Strauch ◽  
Ralf-Udo Ehlers
Keyword(s):  
Water Activity ◽  
Desiccation Tolerance ◽  
Entomopathogenic Nematodes ◽  
Fungal Growth ◽  
Stress Conditions ◽  
Activity Levels ◽  
Energy Reserves ◽  
Poly Ethylene Glycol ◽  
Tolerant Species ◽  
Poly Ethylene

For transport of entomopathogenic nematodes to the user, developmentally arrested dauer juveniles (DJ) are mixed with inert carriers at high density. If quiescence is not induced, DJ will quickly lose energy reserves and die. To induce quiescence DJ can be moderately desiccated. This study investigated the desiccation tolerance by measurement of water activity (-value) tolerated by 50% of populations (WA50) of different Steinernema species and strains. DJ were tested with or without prior adaptation to desiccation stress. Stress conditions were produced by exposure to various concentrations of poly(ethylene glycol) 600. Significant differences in desiccation tolerance were recorded between strains and species, but, except for Steinernema abbasi, not within strains of one species. Without adaptation to stress conditions, the most tolerant species was S. carpocapsae (WA50 = 0.836) followed by S. abbasi (0.86). Adaption to stress by exposure to an -value of 0.95 for 48 h increased tolerance to 0.68 and 0.66, respectively. The least tolerant species were S. kraussei, S. glaseri and S. ethiopiense. Tolerance recorded would allow storage at a water activity that would inhibit growth of bacteria but not of fungi. Analysis of water activity tolerated by only 10% of the population indicated potential for genetic improvement by selective breeding for S. carpocapsae, S. abbasi and S. arenarium to reach water activity levels that would also inhibit fungal growth.

1309 Mechanical Properties of Muscular Activity levels at the Heel Contact

2011 ◽  
Vol 2011.48 (0) ◽  
pp. 423-424
Author(s):  
Masanobu MANNO ◽  
Jyun MATSUI ◽  
Tomokazu ABE ◽  
Toshihide MURAOKA ◽  
Tomohiko FUJIKAWA
Keyword(s):  
Mechanical Properties ◽  
Muscular Activity ◽  
Activity Levels ◽  
Heel Contact

scholarly journals Activation of individual extrinsic thumb muscles and compartments of extrinsic finger muscles

2013 ◽  
Vol 110 (6) ◽  
pp. 1385-1392 ◽  
Author(s):  
J. Alexander Birdwell ◽  
Levi J. Hargrove ◽  
Todd A. Kuiken ◽  
Richard F. ff. Weir
Keyword(s):  
Neural Control ◽  
Muscular Activity ◽  
Middle Finger ◽  
The Other ◽  
Flexor Digitorum Profundus ◽  
Human Hand ◽  
Activity Levels ◽  
Extensor Pollicis Longus ◽  
Flexor Digitorum ◽  
Different Levels

Mechanical and neurological couplings exist between musculotendon units of the human hand and digits. Studies have begun to understand how these muscles interact when accomplishing everyday tasks, but there are still unanswered questions regarding the control limitations of individual muscles. Using intramuscular electromyographic (EMG) electrodes, this study examined subjects' ability to individually initiate and sustain three levels of normalized muscular activity in the index and middle finger muscle compartments of extensor digitorum communis (EDC), flexor digitorum profundus (FDP), and flexor digitorum superficialis (FDS), as well as the extrinsic thumb muscles abductor pollicis longus (APL), extensor pollicis brevis (EPB), extensor pollicis longus (EPL), and flexor pollicis longus (FPL). The index and middle finger compartments each sustained activations with significantly different levels of coactivity from the other finger muscle compartments. The middle finger compartment of EDC was the exception. Only two extrinsic thumb muscles, EPL and FPL, were capable of sustaining individual activations from the other thumb muscles, at all tested activity levels. Activation of APL was achieved at 20 and 30% MVC activity levels with significantly different levels of coactivity. Activation of EPB elicited coactivity levels from EPL and APL that were not significantly different. These results suggest that most finger muscle compartments receive unique motor commands, but of the four thumb muscles, only EPL and FPL were capable of individually activating. This work is encouraging for the neural control of prosthetic limbs because these muscles and compartments may potentially serve as additional user inputs to command prostheses.

scholarly journals Similar prevalence and magnitude of auditory-evoked and visually evoked activity in the frontal eye fields: implications for multisensory motor control

2016 ◽  
Vol 115 (6) ◽  
pp. 3162-3173 ◽  
Author(s):  
Valeria C. Caruso ◽  
Daniel S. Pages ◽  
Marc A. Sommer ◽  
Jennifer M. Groh
Keyword(s):  
Target Location ◽  
Saccadic Eye Movements ◽  
Motor Output ◽  
Visual Signals ◽  
Frontal Eye Fields ◽  
Activity Levels ◽  
Population Activity ◽  
Movement Vector ◽  
Saccade Onset ◽  
Evoked Activity

Saccadic eye movements can be elicited by more than one type of sensory stimulus. This implies substantial transformations of signals originating in different sense organs as they reach a common motor output pathway. In this study, we compared the prevalence and magnitude of auditory- and visually evoked activity in a structure implicated in oculomotor processing, the primate frontal eye fields (FEF). We recorded from 324 single neurons while 2 monkeys performed delayed saccades to visual or auditory targets. We found that 64% of FEF neurons were active on presentation of auditory targets and 87% were active during auditory-guided saccades, compared with 75 and 84% for visual targets and saccades. As saccade onset approached, the average level of population activity in the FEF became indistinguishable on visual and auditory trials. FEF activity was better correlated with the movement vector than with the target location for both modalities. In summary, the large proportion of auditory-responsive neurons in the FEF, the similarity between visual and auditory activity levels at the time of the saccade, and the strong correlation between the activity and the saccade vector suggest that auditory signals undergo tailoring to match roughly the strength of visual signals present in the FEF, facilitating accessing of a common motor output pathway.

scholarly journals Impact of honey-enriched mulberry diet on the energy metabolism of the silkworm, Bombyx mori

2020 ◽  
Vol 12 (2) ◽  
pp. 133-145
Author(s):  
S. Siva Prasad ◽  
R. Madhavi
Keyword(s):  
Energy Metabolism ◽  
Oxidative Phosphorylation ◽  
Bombyx Mori ◽  
Larval Stage ◽  
Fat Body ◽  
Activity Levels ◽  
Energy Reserves ◽  
Related Energy ◽  
Energy Needs ◽  
Utilization Patterns

The present study was taken-up with a view to clearly define the role of oxidative phosphorylation vis-a-vis transdeamination in Bombyx mori metamorphosis, under the influence of honey-enriched mulberry diet. Therefore, the study examined the accumulation and utilization patterns of carbohydrate (glycogen, trehalose, glucose) and non-carbohydrate energy reserves (proteins, amino acids) in its fat body during larval, pupal and adult stages. In accordance with Hutchinson’s investment principle, the energy reserves invested during larval stage are partly used in pupal stage and those invested during larval and pupal stages are used in adult stage. Their utilization patterns are correlated with the activity levels of succinate (SDH) and glutamate (GDH) dehydrogenases and aspartate (AAT) and alanine (ALAT) aminotransferases and changes thereof were interpreted in terms of glycolytic oxidative phosphorylation and non-glycolytic transdeamination.  The trends in mass incorporation rates vis-à-vis enzyme activities indicated that the metabolism-related energy needs of all metamorphic events are majorly met through a gluconeogenetic mechanism called transdeamination, while the behavioural-related energy demands of larval and pupal stages are fulfilled through glycolytic-based oxidative phosphorylation. The activity trends further indicated that AAT plays major role in meeting the energy needs of larva and pupa, while GDH predominantly meets the energy requirements of reproduction in adults. The honey-enriched mulberry diet showed stage-specific and pathway-specific impacts on energy metabolism. It positively reinforced the energy metabolism in larval stage, but showed no significant effect in pupal and adult stages. Similarly, it showed more promising effect on glycolytic-oxidative phosphorylation and null or neutral effect on transdeamination.

scholarly journals Increasing physical activity by Gamification among Brazilian high school students: a pilot study

2021 ◽  
Vol 26 ◽  
pp. 1-7
Author(s):  
Eduardo Lucia Caputo ◽  
Natan Feter ◽  
Ricardo Alt ◽  
Jayne Santos Leite ◽  
Alysson Nogueira Rodrigues ◽  
...  
Keyword(s):  
Physical Activity ◽  
High School ◽  
High School Students ◽  
Pilot Study ◽  
Activity Levels ◽  
School Students ◽  
Active Life ◽  
Steps Per Day ◽  
Quasi Experimental ◽  
Experiment Duration

This pilot study aimed to evaluate the effectiveness of a Gamification-based intervention on physical activity levels of High School students. This quasi experimental study was conducted in two federal high schools in Southern Brazil. One class from each school was selected to be either intervention (INT) or control (CON) group. Experiment duration was two weeks, and both groups downloaded My Active Life app. INT group (n = 69) participants received daily app alerts with messages of encouragement to practice physical activity. They also received a score based on the percentage of goal achieved. CON group (n = 35) only had access to total number of steps per day. INT group showed a lower decrease in physical activity at school compared to CON group (p = 0.024). No effect of intervention was observed in physical activity out of school (p = 0.911). Gamification-based intervention prevented a decrease in physical activity at school among male (F = 10.680; p = 0.004), students at first half of high school (F = 12.668; p = 0.002), and adequate body mass index (F = 4.640; p = 0.037), and with lower perception of barriers to physical activity (F = 5.437; p = 0.024). Although we did not observe an increase in physical activity at school, gamification-based intervention may mitigate its decrease among adolescents.

scholarly journals Experiments on the Influence of Light on the Behaviour of Polyzoan Larvae

1960 ◽  
Vol 37 (4) ◽  
pp. 783-800
Author(s):  
J. S. RYLAND
Keyword(s):  
Light Beam ◽  
Small Proportion ◽  
Laboratory Experiments ◽  
Water Bath ◽  
Bugula Neritina ◽  
Parallel Beam ◽  
Algal Cover ◽  
Behavioural Responses ◽  
Fucus Serratus ◽  
Marine Larvae

1. An apparatus is described for investigating the photic responses of marine larvae. A parallel beam of light is projected along horizontal Perspex troughs containing the larvae, while the use of a water bath prevents their being subjected to a rise in temperature. 2. Using a light beam of 5000 lux at normal summer sea temperatures, plotting the positions of the larvae in the troughs at regular intervals has revealed four types of behaviour: I. Larvae at first all photopositive, later all becoming photonegative; for example, Celleporella hyalina. II. Larvae at first all photopositive, only a small proportion of them later becoming photonegative; for example, Bugula neritina. III. Larvae photopositive throughout the length of their natant phase; for example, Flustrellidra hispida. IV. Larvae showing no response at all to directional illumination; for example, Alcyonidium polyoum. 3. It has been shown that the reversal of the sign of reaction to light in Celleporella hyalina larvae is dependent on the passage of time; it does not require their exposure to a certain amount of light for its inception. 4. When disks cut from Fucus serratus fronds were placed in the troughs as a substrate for settlement, the majority of Celleporella hyalina larvae developed a photonegative reaction before they metamorphosed. 5. Horizontally and vertically placed panels in the Menai Straits received settlement of polyzoans on all surfaces free from sediment and dense algal cover. These adverse factors would have masked any selection based on the behavioural responses of the larvae. 6. Laboratory experiments with opaque panels suspended vertically, obliquely and horizontally have shown that Celleporella hyalina larvae settle on the side away from the light. Thus they normally settle on the undersurfaces of horizontal and oblique panels, but this pattern is reversed if the panels are lit from below. Settlement on panels in the sea would therefore seem to depend on the reactions of larvae to light as well as on the unfavourability of upward-facing surfaces. 7. The nature of the larval responses is discussed.

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