scholarly journals Vision does not impact walking performance in Argentine ants

2020 ◽  
Vol 223 (20) ◽  
pp. jeb228460
Author(s):  
Glenna T. Clifton ◽  
David Holway ◽  
Nicholas Gravish
Keyword(s):  
Vision Loss ◽  
Obstacle Detection ◽  
Argentine Ant ◽  
Tactile Sensing ◽  
Long Distance ◽  
Uneven Terrain ◽  
Approach Speed ◽  
Close Range ◽  
Walking Performance ◽  
Walking Speeds

ABSTRACTMany walking insects use vision for long-distance navigation, but the influence of vision on rapid walking performance that requires close-range obstacle detection and directing the limbs towards stable footholds remains largely untested. We compared Argentine ant (Linepithema humile) workers in light versus darkness while traversing flat and uneven terrain. In darkness, ants reduced flat-ground walking speeds by only 5%. Similarly, the approach speed and time to cross a step obstacle were not significantly affected by lack of lighting. To determine whether tactile sensing might compensate for vision loss, we tracked antennal motion and observed shifts in spatiotemporal activity as a result of terrain structure but not illumination. Together, these findings suggest that vision does not impact walking performance in Argentine ant workers. Our results help contextualize eye variation across ants, including subterranean, nocturnal and eyeless species that walk in complete darkness. More broadly, our findings highlight the importance of integrating vision, proprioception and tactile sensing for robust locomotion in unstructured environments.

scholarly journals Vision does not impact walking performance in Argentine ants

2020 ◽  
Author(s):  
G.T. Clifton ◽  
D. Holway ◽  
N. Gravish
Keyword(s):  
Vision Loss ◽  
Argentine Ant ◽  
Tactile Sensing ◽  
Long Distance ◽  
Argentine Ants ◽  
Uneven Terrain ◽  
Approach Speed ◽  
Close Range ◽  
Walking Performance ◽  
Walking Speeds

AbstractMany walking insects use vision for long-distance navigation, but the influence of vision in detecting close-range obstacles and directing the limbs to maintain stability remains largely untested. We compared Argentine ant workers in light versus darkness while traversing flat and uneven terrain. In darkness, ants reduced flat-ground walking speeds by only 5%. Similarly, neither the approach speed nor the time to cross a step obstacle was affected by lighting. To determine if tactile sensing might compensate for vision loss, we tracked antennal motion and observed shifts in spatiotemporal activity due to terrain structure but not illumination. Together, these findings suggest that vision does not impact walking performance in Argentine ant workers. Our results help contextualize eye variation across ants, including subterranean, nocturnal, and eyeless species that walk in complete darkness. More broadly, our findings highlight the importance of integrating vision, proprioception, and tactile sensing for robust locomotion in unstructured environments.

scholarly journals Uneven substrates constrain walking speed in ants through modulation of stride frequency more than stride length

2020 ◽  
Vol 7 (3) ◽  
pp. 192068 ◽  
Author(s):  
G. T. Clifton ◽  
D. Holway ◽  
N. Gravish
Keyword(s):  
Stride Length ◽  
Field Experiments ◽  
Walking Speed ◽  
Stride Frequency ◽  
Mixed Effect ◽  
Uneven Terrain ◽  
Flat Substrate ◽  
Walking Performance ◽  
Kinematic Mechanisms ◽  
Walking Speeds

Natural terrain is rarely flat. Substrate irregularities challenge walking animals to maintain stability, yet we lack quantitative assessments of walking performance and limb kinematics on naturally uneven ground. We measured how continually uneven 3D-printed substrates influence walking performance of Argentine ants by measuring walking speeds of workers from laboratory colonies and by testing colony-wide substrate preference in field experiments. Tracking limb motion in over 8000 videos, we used statistical models that associate walking speed with limb kinematic parameters to compare movement over flat versus uneven ground of controlled dimensions. We found that uneven substrates reduced preferred and peak walking speeds by up to 42% and that ants actively avoided uneven terrain in the field. Observed speed reductions were modulated primarily by shifts in stride frequency instead of stride length (flat R 2 : 0.91 versus 0.50), a pattern consistent across flat and uneven substrates. Mixed effect modelling revealed that walking speeds on uneven substrates were accurately predicted based on flat walking data for over 89% of strides. Those strides that were not well modelled primarily involved limb perturbations, including missteps, active foot repositioning and slipping. Together these findings relate kinematic mechanisms underlying walking performance on uneven terrain to ecologically relevant measures under field conditions.

scholarly journals Extracellular Vesicles and MicroRNA: Putative Role in Diagnosis and Treatment of Diabetic Retinopathy

Antioxidants ◽  
2020 ◽  
Vol 9 (8) ◽  
pp. 705 ◽  
Author(s):  
Beatriz Martins ◽  
Madania Amorim ◽  
Flávio Reis ◽  
António Francisco Ambrósio ◽  
Rosa Fernandes
Keyword(s):  
Diabetic Retinopathy ◽  
Extracellular Vesicles ◽  
Vision Loss ◽  
Current Knowledge ◽  
Critical Role ◽  
Cell Communication ◽  
Cell Junctions ◽  
Low Grade ◽  
Long Distance ◽  
Advanced Stages

Diabetic retinopathy (DR) is a complex, progressive, and heterogenous retinal degenerative disease associated with diabetes duration. It is characterized by glial, neural, and microvascular dysfunction, being the blood-retinal barrier (BRB) breakdown a hallmark of the early stages. In advanced stages, there is formation of new blood vessels, which are fragile and prone to leaking. This disease, if left untreated, may result in severe vision loss and eventually legal blindness. Although there are some available treatment options for DR, most of them are targeted to the advanced stages of the disease, have some adverse effects, and many patients do not adequately respond to the treatment, which demands further research. Oxidative stress and low-grade inflammation are closely associated processes that play a critical role in the development of DR. Retinal cells communicate with each other or with another one, using cell junctions, adhesion contacts, and secreted soluble factors that can act in neighboring or long-distance cells. Another mechanism of cell communication is via secreted extracellular vesicles (EVs), through exchange of material. Here, we review the current knowledge on deregulation of cell-to-cell communication through EVs, discussing the changes in miRNA expression profiling in body fluids and their role in the development of DR. Thereafter, current and promising therapeutic agents for preventing the progression of DR will be discussed.

Quantifying conspicuousness and sexual dimorphism of the plumage in birds: a new approach

1997 ◽  
Vol 75 (12) ◽  
pp. 1972-1981 ◽  
Author(s):  
Yves de Repentigny ◽  
Henri Ouellet ◽  
Raymond McNeil
Keyword(s):  
Sexual Dimorphism ◽  
The Body ◽  
Human Vision ◽  
Long Distance ◽  
New Approach ◽  
Field Guides ◽  
Close Range ◽  
Colour System ◽  
High Degree ◽  
Munsell System

In studies of sexual selection in birds, it is necessary to quantify the conspicuousness and sexual dimorphism of the plumage. We present a method, based on the Munsell colour system, that is easier to use than spectroradiometric techniques. It is based on measurable and repeatable data, although it is dependent on human vision. It provides indices of sexual dimorphism and incorporates aspects of close-range and long-distance conspicuousness. Ten species of Emberezidae were chosen to illustrate the procedure, and it was tested using naive observers. It consists of dividing the body of a bird into regions and matching the colour of each region to chips in a colour guide. The following indices based on the parameters of the Munsell system were selected: value (V), chroma (C), and Munsell power (V∙C), which measure conspicuousness independently of the background; Wv, Wc, and Wv∙c, which measure the contrast between the colours in the plumage; Bv, Bc, and Bv∙c, which measure the contrast between the bird and its background; and Dv, Dc, and Dv∙c, which are the indices of sexual dimorphism of the plumage. There was a high degree of agreement among the naive observers, and the scores obtained using field guides did not differ significantly from those recorded on museum specimens. One of the dimorphism indices (Dv∙c) was found to give more information than the others. However, our results indicate that conspicuousness and dimorphism indices should not be used individually because they are interdependent, and that they should be used in conjunction with multivariate analyses. Also, the proposed method incorporates long-distance conspicuousness into the results.

Cues Used in Searching for Food By Red-Winged Blackbirds (Agelaius Phoeniceus)

Behaviour ◽  
1973 ◽  
Vol 46 (1-2) ◽  
pp. 174-187 ◽  
Author(s):  
John Alcock
Keyword(s):  
Sunflower Seed ◽  
Visual Cues ◽  
Previous Experience ◽  
Agelaius Phoeniceus ◽  
Foraging Efficiency ◽  
Scanning Strategy ◽  
Long Distance ◽  
The Third ◽  
Close Range ◽  
Initial Tendency

AbstractSixteen red-winged blackbirds (Agelaius phoeniceus) were given an opportunity on each of four consecutive days to search for food items partly hidden in a wooden "food maze". The birds were divided equally into four groups. Each group on Days 1 and 2 of the experiment hunted for one of two baits placed on one of two separate rows of holes in the food maze (either sunflower seed bits in the lower row or seeds in the upper row or mealworm halves in the lower row or mealworms in the upper row). On the second day of the experiment the birds' foraging efficiency had usually improved with the redwings requiring less time to find ten baits. This improvement was linked to the adoption of a long distance scanning strategy which replaced the birds' initial tendency to inspect each hole at close range. On the third day of the experiment the birds were offered the same food item as on Days 1 and 2 but this time equally distributed in the upper and lower rows instead of entirely in one or the other. The redwings' previous experience affected their searching pattern. Birds that had been hunting and finding food only in the upper row continued to concentrate their efforts there. Birds that had been offered food in the lower row of holes initially took several baits there before switching to the upper row baits. On the fourth day of the experiment birds were offered two baits instead of just one. Again previous experience biased the searching behavior of the birds. Redwings that had on earlier days been hunting solely for mealworms usually removed many larvae before finding their first sunflower seed bit. Birds that had been searching for seeds quickly took several before switching to mealworms. It appears likely that redwings are sensitive to both locational and visual cues associated with prey and learn to use them while foraging. These results were discussed in the context of L. TINBERGENS search image hypothesis.

scholarly journals Rough substrates constrain walking speed in ants through modulation of stride frequency and not stride length

2019 ◽  
Author(s):  
G.T. Clifton ◽  
D. Holway ◽  
N. Gravish
Keyword(s):  
Stride Length ◽  
Field Experiments ◽  
Walking Speed ◽  
Stride Frequency ◽  
Rough Terrain ◽  
Flat Substrate ◽  
Walking Performance ◽  
Natural Terrain ◽  
Kinematic Mechanisms ◽  
Walking Speeds

AbstractNatural terrain is rarely flat. Substrate irregularities challenge walking animals to maintain stability, yet we lack quantitative assessments of walking performance and limb kinematics on naturally rough ground. We measured how continually rough 3D-printed substrates influence walking performance of Argentine ants by measuring walking speeds of workers from lab colonies and by testing colony-wide substrate preference in field experiments. Tracking limb motion in over 8,000 videos, we used statistical models that associate walking speed with limb kinematic parameters to compare movement over flat versus rough ground. We found that rough substrates reduced preferred and peak walking speeds by up to 42% and that ants actively avoided rough terrain in the field. Observed speed reductions were modulated primarily by shifts in stride frequency and not stride length, a pattern consistent across flat and rough substrates. Modeling revealed that walking speeds on rough substrates were accurately predicted based on flat walking data for over 89% of strides. Those strides that were not well modeled primarily involved limb perturbations, including missteps, active foot repositioning, and slipping. Together these findings relate kinematic mechanisms underlying walking performance on rough terrain to ecologically-relevant measures under field conditions.

An Experimental Study of Driver and Pedestrian Interaction during the Crossing Conflict

1975 ◽  
Vol 17 (5) ◽  
pp. 514-527 ◽  
Author(s):  
A. Katz ◽  
D. Zaidel ◽  
A. Elgrishi
Keyword(s):  
Situational Factors ◽  
Relative Importance ◽  
Long Distance ◽  
The Road ◽  
Point Of Entry ◽  
Road Design ◽  
Approach Speed ◽  
Oncoming Vehicle ◽  
Vehicle Velocity ◽  
Approach Velocity

A controlled experiment was conducted to determine the relative importance of pedestrian, vehicle, and situational factors in influencing drivers to give way to crossing pedestrians. The following variables were combined in a complete factorial design: (1) type of crossing; (2) distance between oncoming vehicle and pedestrian; (3) orientation of pedestrian; (4) number of pedestrians; and (5) approach velocity of vehicle. Trained pedestrians performed the start of an ordinary street crossing attempt and interacted with regular drivers whose response was measured in terms of changes in vehicle velocity. The experiment was replicated at two sites for a total of 960 crossing trials. The results show that drivers slowed down, or stopped more, for crossing pedestrians when: (1) the approach speed of the vehicle was low; (2) the crossing took place on a marked crosswalk; (3) there was a relatively long distance between the vehicle and the pedestrian's point of entry into the road; (4) a group of pedestrians, rather than an individual, attempted to cross; and, (5) the pedestrian did not look at the approaching vehicle. Additionally, female drivers and older drivers slowed down more than other drivers. Implications of the results for pedestrian safety, road design, and further research are discussed.

PARAMETER ANALYSIS OF A REMOTELY CONTROLLED HOME MONITORING SYSTEM USING MOBILE ROBOT VIA CAMERA

2017 ◽  
Vol 79 (2) ◽  
Author(s):  
Mariam Md Ghazaly ◽  
Ho Carl Choon ◽  
Mohd Amran Md Ali ◽  
Zulkeflee Abdullah ◽  
Soo Kok Yew ◽  
...  
Keyword(s):  
Mobile Robot ◽  
Monitoring System ◽  
Robot Control ◽  
Pulse Width Modulation ◽  
Detection System ◽  
Home Monitoring ◽  
Obstacle Detection ◽  
Parameter Analysis ◽  
Experimental Result ◽  
Long Distance

In this paper, the performance and prototype of a remotely-controlled home monitoring mobile robot for security and surveillance purposes were discussed. Home monitoring system has been one of the basic infrastructures that is being used in most of the residential compound. However, traditional CCTV system, which requires supporting surfaces and high equipment cost, has forced human to search for an alternative. Thus, this project provided a more flexibility and mobility to the home monitoring system, which consisted of an obstacle detection system and a camera. After discussing the conception of the project, as part of the experiment aspect method, experiment setup and result were presented. In this paper, the objectives also looked into the sensitivity of the obstacle avoidance system, to design and develop a remotely-controlled home monitoring robot, to design and develop a networking system for long distance robot control and to analyze the performance of the motor in terms of pulse width modulation (PWM). In conclusion, the experimental result proved that the proposed project was successfully developed with detailed supporting data.

Effects of Auditory Stimuli on Beat-Synchronized Long Distance Walking: Part A - Energize on Country Music

2021 ◽  
Author(s):  
Gregory Shay
Keyword(s):  
Step Length ◽  
Country Music ◽  
Test Subject ◽  
Auditory Stimuli ◽  
Human Response ◽  
Long Distance ◽  
Outdoor Setting ◽  
Walking Performance ◽  
Velocity Effect ◽  
Rudimentary Form

In well documented studies, walking and music have independently shown substantial medical, health, productivity, and other human benefits. When music is combined with walking, and especially when the walking is done in synchrony to the beat, the music can stimulate faster walking without apparent awareness, the “velocity effect”. Some studies have reported that music that is either familiar, more enjoyable, and/or has higher “groove” tends to be more stimulating, and that some music can actually be sedating resulting in a slower speed relative to that of walking to a metronome at the same cadence. Research illuminating the velocity effect has mostly been conducted over relatively short stepping distances in a laboratory or similar outdoor setting. The current study examines walking on a real-world long distance outdoor track with a single genre of music that was at least somewhat familiar and somewhat enjoyable to the test subject. In this study, the test subject stepped in self-instructed synchrony with confirmed high accuracy to two types of auditory stimuli – either to the beat of a metronome (a presumed neutral source or what might be considered a most rudimentary form of music), or to the beat of a broad-spectrum of country music continuously over a 2-mile course. Nine metronome tempos and twenty-one country music tempos were examined in a walkable range of 90 to 130 beats per minute (BPM), and the effects of the music and metronome on walking performance were examined and quantified. Overall, the mix of country music was significantly more energizing than the metronome providing a relatively consistent 10% increase in step length and a resulting 10% increase in speed over the entire tempo/cadence range. Speed as a function of tempo was essentially linear in the beat range for both auditory stimuli with an apparent increase in speed relative to the trendlines occurring near 120 BPM, a preferred human response frequency reported in some prior investigations.

About the traumatic ring around the entrance hole of the gunshot wounds

1927 ◽  
Vol 23 (1) ◽  
pp. 132-133
Author(s):  
A. D. Grigoriev
Keyword(s):  
Centrifugal Force ◽  
Gunshot Wounds ◽  
Long Distance ◽  
Entrance Wound ◽  
Close Range ◽  
Entrance Hole

The author points out that when shots are fired at a long distance, the bullet, having traveled a long distance, loses its centrifugal force and acts only percussively, more slowly passing through the thickness of tissues and injuring them much more than when fired at close range, so that a traumatic ring is formed in the circumference of the entrance wound.

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