Resource defense and priority of access to food by the mate in pigeons

1986 ◽  
Vol 64 (9) ◽  
pp. 1889-1892 ◽  
Author(s):  
Louis Lefebvre ◽  
Derin Henderson
Keyword(s):  
Food Source ◽  
Resource Defense ◽  
Pair Bonds ◽  
Highly Correlated ◽  
Time Required ◽  
Access To Food ◽  
Competition For Resources

When pigeons in a group compete for access to a spatially restricted food source, feeding by one bird may coincide with defense of the area around the source by that bird's mate. Defense while the mate is feeding varies between individuals, between trials, and between sexes, males defending more than females. Priority of access to food, as measured by the time required for 5 min of feeding, is highly correlated with the amount of defense performed by the mate. Satiation reduces but does not abolish defense. Birds within a mated pair have similar positions in the priority of access hierarchy. Pair bonds in pigeons may partially function as reciprocal coalition systems used in competition for resources.

Seasonal differences in habitat use and fat reserves in an arctic muskrat population

1989 ◽  
Vol 67 (2) ◽  
pp. 305-313 ◽  
Author(s):  
Dennis E. Jelinski
Keyword(s):  
Habitat Use ◽  
Breeding Season ◽  
Discriminant Function ◽  
Function Analysis ◽  
Good Condition ◽  
Food Habit ◽  
Winter Habitat ◽  
Resource Defense ◽  
Fat Reserves ◽  
Access To Food

Differences in summer and winter habitat use by muskrats (Ondatra zibethicus) were studied in the Mackenzie River Delta, Northwest Territories, Canada. Quantitative data consisting of 11 habitat variables were obtained from 73 winter and 119 summer burrow sites. The single discriminant function derived from a discriminant function analysis of summer and winter burrow sites was strongly correlated with variables interpreted as describing food, cover, and overwinter survival of muskrats. During summer, muskrat burrows were closer to shallow water, on gentler slopes with greater cover, and occurred closer to stands of horsetail (Equisetum fluviatile) than in winter. Food habit analyses revealed that high-protein E. fluviatile was the most frequently consumed species in summer. Muskrats of both sexes were found to enter the breeding season in extremely good condition when judged on the basis of body fat; the costs of breeding, lactation, and resource defense are hypothesized to account for the low-fat condition noted at the onset of winter. Prior to winter, muskrats relocated to deep-water sites, possibly to maintain access to food and (or) forage on the energy-rich roots and rhizomes of submerged macrophytes. The change in habitat use, coupled with physiological adaptations to cold, is suggested to account for the winter recovery in fat reserves. These same reserves can be mobilized in spring at the onset of the metabolically demanding breeding season.

Death in the Distance: Mortality Risk as Information for Foraging Ants

Behaviour ◽  
1990 ◽  
Vol 112 (1-2) ◽  
pp. 23-35 ◽  
Author(s):  
Peter Nonacs
Keyword(s):  
Food Quality ◽  
Mortality Risk ◽  
Food Source ◽  
Critical Factor ◽  
High Rate ◽  
Food Patch ◽  
Lasius Pallitarsis ◽  
Access To Food ◽  
The Way

AbstractAnt foragers are known to communicate food presence in distant patches, but do they also communicate information about distant mortality risk? Recruitment to a food source in a laboratory Lasius pallitarsis colony depended upon whether the initial returning foragers had encountered mortality risk (a larger Formica subnuda) and the quality of the food they found. When food quality was high, risk appeared to not affect recruitment; when quality was low, risk inhibited foraging. In a second experiment, L. pallitarsis colonies had access to food of several qualities through a divided trail, which forced foragers to take different routes to and from the food patch. Danger was either entirely absent, present only on the way to the patch, present only on the way from the patch, or along both routes. When food quality was poor colonies recruited to food when risk was absent, but risk anywhere significantly reduced the level of foraging. This included the situation where only returning foragers could encounter danger, which strongly suggests that their behaviour was a critical factor in whether nestmates would continue foraging. When food quality was moderate, only treatments with risk on the way to the food significantly inhibited foraging. When food quality was good, colonies continued to forage at a high rate, irrespective of presence or location or risk. In total, L. pallitarsis foragers appear to communicate and use information about both food and mortality risk in deciding whether to exploit patches.

The inhibition of photosynthesis under water deficit conditions is more severe in flecked than uniform irradiance in rice (Oryza sativa) plants

2017 ◽  
Vol 44 (4) ◽  
pp. 464 ◽  
Author(s):  
Jiali Sun ◽  
Qiangqiang Zhang ◽  
Muhammad Adnan Tabassum ◽  
Miao Ye ◽  
Shaobing Peng ◽  
...  
Keyword(s):  
Water Deficit ◽  
Photosynthetic Rate ◽  
Light Level ◽  
Light Period ◽  
Low Light ◽  
Physiological Basis ◽  
Variable Light ◽  
Highly Correlated ◽  
Time Required ◽  
Hydroponically Grown

Water deficit is considered the major environmental factor limiting leaf photosynthesis, and the physiological basis for decreased photosynthesis under water deficit has been intensively studied with steady irradiance. Leaves within a canopy experience a highly variable light environment in magnitude and time, but the effect of water deficit on photosynthesis in fluctuating irradiance is not well understood. Two rice cultivars with different drought tolerance, Champa and Yangliangyou 6 (YLY6), were hydroponically grown under well-watered, 15% (m/v) and 20% PEG (polyethylene glycol, 6000 Da) induced water deficit conditions. The inhibition of steady-state photosynthesis in Champa is more severe than YLY6. The maximum Rubisco carboxylation capacity (Vcmax) and maximum electron transport capacity (Jmax) were decreased under 20% PEG treatment in Champa, whereas less or no effect was observed in YLY6. The induction state (IS%, which indicates photosynthesis capacity after exposure of low-light period) of both leaf photosynthetic rate (A) and stomatal conductance (gs) was highly correlated, and was significantly decreased under water deficit conditions in both cultivars. Water deficit had no significant effect on the time required to reach 50 or 90% of the maximum photosynthetic rate (T50%,A and T90%,A) after exposure to high-light level, but significantly led to a greater decrease in photosynthetic rate in the low-light period under flecked irradiance (Amin-fleck) relative to photosynthetic rate in the same light intensity of continuously low-light period (Ainitial). The lower IS% of A and more severe decrease in Amin-fleck relative to Ainitial will lead to a more severe decrease in integrated CO2 fixation under water deficit in flecked compared with uniform irradiance.

Dominance affects resource partitioning in pigeons, but pair bonds do not

1996 ◽  
Vol 74 (5) ◽  
pp. 833-840 ◽  
Author(s):  
David Robichaud ◽  
Louis Lefebvre ◽  
Lucie Robidoux
Keyword(s):  
Resource Partitioning ◽  
Dominance Rank ◽  
Columba Livia ◽  
Pair Bonds ◽  
In Captivity ◽  
Lower Ranking ◽  
Opposite Sex ◽  
Feeding Trials ◽  
Access To Food ◽  
Diet Shifts

Pigeons (Columba livia) show individual feeding specializations both in the field and in captivity. In competitive feeding conditions, these specializations change in a way that decreases dietary overlap between birds. We examine two potential status determinants of feeding competition, dominance and pair bonds. In pigeons, pair bonds are used in aggressive feeding coalitions at defendable patches, while dominance affects both feeding rate and priority of access to food. We compared the seed choices of pigeons feeding alone and in competitive conditions with those of a conspecific. In experiment 1, the competitor was either the mate or a familiar nonmate of the opposite sex; in experiment 2, the dominance rank of the competitors was known from a round-robin series of dyadic encounters in the presence of a defendable feeder. Pair bonds had no effect on competitive diet shifts, but dominance did: in competition, lower ranking pigeons ate less of the seed type they specialized on when feeding alone, while higher ranking pigeons ate more. Confirming previous results on resource partitioning, food choice showed less overlap between individuals in competition than in solitary feeding trials, but the magnitude of the change was not proportional to initial overlap.

scholarly journals Automated identification of piglet brain tissue from MRI images using Region-Based Convolutional Neural Networks

2021 ◽  
Author(s):  
Kayla L. Stanke ◽  
Ryan Larsen ◽  
Laurie Rund ◽  
Brian J Leyshon ◽  
Allison Louie ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Neural Networks ◽  
Brain Tissue ◽  
Convolutional Neural Networks ◽  
Visual Inspection ◽  
Resonance Imaging ◽  
Automated Identification ◽  
Acceptable Accuracy ◽  
Highly Correlated ◽  
Time Required

Magnetic Resonance Imaging is an important tool for characterizing volumetric changes of the piglet brain during development. These analyses have been aided by the development of piglet brain atlases which are based on averages drawn from multiple piglets. Because these atlases typically contain only brain tissue, their use is limited to “brain extracted” images from which the surrounding tissues have been removed. Brain extractions, or segmentations, are typically performed manually. This approach is time-intensive and can lead to variation between segmentations when multiple raters are used. Automated segmentations processes are important for reducing the time required for analyses and improving the uniformity of the segmentations. Here we demonstrate the use of region-based recurrent convolutional neural networks (RCNNs) on a dataset consisting of 32 piglet brains. The RCNNs are trained from manual segmentations of sets of 27 piglets and then applied to sets of the remaining 5 piglets. The volumes of the machine-generated brain masks are highly correlated with those of the manually generated masks, and visual inspection of the segmentations show acceptable accuracy. These results demonstrate that neural networks provide a viable tool for the segmentation of piglet brains.

Mentally Simulated Reaches for Visual Objects: Effects of Stimulus Orientation and Biomechanical Constraints

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 199-199
Author(s):  
S H Johnson
Keyword(s):  
Picture Plane ◽  
Response Hand ◽  
Left Hand ◽  
Visual Objects ◽  
Series Of Experiments ◽  
Biomechanical Constraints ◽  
Highly Correlated ◽  
Time Required ◽  
The Right ◽  
Biomechanical Factors

Recent evidence suggests that mentally simulating an action involves many of the same neuropsychological mechanisms as overt performance. A series of experiments were conducted to evaluate whether representations involved in mentally simulated reaches are constrained by the same biomechanical factors that limit actual movements. Subjects were asked to use either the right or the left hand to acquire a dowel presented visually in one of 24 different orientations within the picture plane. In reaching studies, subjects responded by grasping the target using either an overhand or underhand grip; in the mentally simulated studies, subjects responded by vocally indicating whether they would prefer an overhand or underhand grip if they were to actually grasp the object. Results indicate substantial correspondence between actual and mentally simulated reaching. Grip preferences in both situations are highly correlated, and reflect biomechanical constraints on rotation of the forearm. In both actual and mentally simulated tasks, subjects show clear preferences for grips that minimise perceived awkwardness. In contrast to related work, the time required to perform mentally simulated reaches for visual objects was found not to increase linearly with distance from the resting posture of the response hand. Findings are discussed with respect to the hypothesis that actual and mentally simulated actions involve the same internal representations.

scholarly journals Scoring divergent thinking tests by computer with a semantics-based algorithm

2016 ◽  
Vol 12 (2) ◽  
pp. 210-220 ◽  
Author(s):  
Kenes Beketayev ◽  
Mark A. Runco
Keyword(s):  
Large Scale ◽  
Divergent Thinking ◽  
Computation Time ◽  
Semantic Networks ◽  
Future Research ◽  
Scoring Methods ◽  
Conceptual Structures ◽  
Highly Correlated ◽  
The Many ◽  
Time Required

Divergent thinking (DT) tests are useful for the assessment of creative potentials. This article reports the semantics-based algorithmic (SBA) method for assessing DT. This algorithm is fully automated: Examinees receive DT questions on a computer or mobile device and their ideas are immediately compared with norms and semantic networks. This investigation compared the scores generated by the SBA method with the traditional methods of scoring DT (i.e., fluency, originality, and flexibility). Data were collected from 250 examinees using the “Many Uses Test” of DT. The most important finding involved the flexibility scores from both scoring methods. This was critical because semantic networks are based on conceptual structures, and thus a high SBA score should be highly correlated with the traditional flexibility score from DT tests. Results confirmed this correlation (r = .74). This supports the use of algorithmic scoring of DT. The nearly-immediate computation time required by SBA method may make it the method of choice, especially when it comes to moderate- and large-scale DT assessment investigations. Correlations between SBA scores and GPA were insignificant, providing evidence of the discriminant and construct validity of SBA scores. Limitations of the present study and directions for future research are offered.

Red blood cells are superior to plasma for predicting subcutaneous trans fatty acid composition in beef heifers

2020 ◽  
Vol 100 (3) ◽  
pp. 570-576
Author(s):  
P. Vahmani ◽  
D.C. Rolland ◽  
H.C. Block ◽  
M.E.R. Dugan
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Vaccenic Acid ◽  
Subcutaneous Fat ◽  
Barley Grain ◽  
Blood Component ◽  
Beef Heifers ◽  
Hydrogenated Vegetable Oils ◽  
Highly Correlated ◽  
Time Required

The trans (t)-18:1 content in beef has become more of interest as partially hydrogenated vegetable oils are removed from foods. Predicting t-18:1 early in the feeding period would be useful if limitations are put on t-18:1 in beef. To determine which blood component is better related to backfat, proportions of t10-18:1 and t11-18:1 (vaccenic acid) were measured in heifer red blood cells (RBC) and plasma (N = 14) after 0, 28, 56, and 76 d on a barley-grain-based diet, and correlated with post-slaughter subcutaneous fat (SCF). Total t-18:1 declined in both RBC and plasma during late finishing (P < 0.05). At 28 d, t11-18:1 decreased and t10-18:1 increased in RBC and plasma (P < 0.05). By 76 d, t10-18:1 declined to 0 d levels. RBC and plasma t-18:1 compositions were highly correlated (t10-18:1, r ≥ 0.7, P ≤ 0.02; t11-18:1, r ≥ 0.51, P ≤ 0.06). Correlations with post-slaughter backfat were, however, consistently greater for RBC compared with plasma. The use of RBC t-18:1 composition may, therefore, be superior to plasma for predicting t-18:1 in SCF, and the length of finishing could be useful for manipulating t-18:1 in beef. The time required for changes in t18:1 in RBC to reflect in changes in SCF still, however, needs to be determined to establish optimal durations for beneficial modification.

The Critical Point Drying Method Applied to Scanning Electron Microscopy of L-929 Cells

1970 ◽  
Vol 28 ◽  
pp. 278-279
Author(s):  
Charles TurnbiLL ◽  
Delbert E. Philpott
Keyword(s):  
Electron Microscopy ◽  
Carbon Dioxide ◽  
Surface Tension ◽  
Critical Point ◽  
Freeze Drying ◽  
Attractive Alternative ◽  
Crystal Formation ◽  
Critical Point Drying ◽  
Time Required ◽  
Scanning Electron

The advent of the scanning electron microscope (SCEM) has renewed interest in preparing specimens by avoiding the forces of surface tension. The present method of freeze drying by Boyde and Barger (1969) and Small and Marszalek (1969) does prevent surface tension but ice crystal formation and time required for pumping out the specimen to dryness has discouraged us. We believe an attractive alternative to freeze drying is the critical point method originated by Anderson (1951; for electron microscopy. He avoided surface tension effects during drying by first exchanging the specimen water with alcohol, amy L acetate and then with carbon dioxide. He then selected a specific temperature (36.5°C) and pressure (72 Atm.) at which carbon dioxide would pass from the liquid to the gaseous phase without the effect of surface tension This combination of temperature and, pressure is known as the "critical point" of the Liquid.

Search mode for rapid detection of virus particles

1991 ◽  
Vol 49 ◽  
pp. 286-287
Author(s):  
O. E. Bradfute
Keyword(s):  
Electron Microscopy ◽  
Rapid Detection ◽  
Plant Virus ◽  
Low Dose ◽  
Search Mode ◽  
Virus Diseases ◽  
Virus Particles ◽  
Focus Image ◽  
Time Required ◽  
Rapid Switching

Electron microscopy is frequently used in preliminary diagnosis of plant virus diseases by surveying negatively stained preparations of crude extracts of leaf samples. A major limitation of this method is the time required to survey grids when the concentration of virus particles (VPs) is low. A rapid survey of grids for VPs is reported here; the method employs a low magnification, out-of-focus Search Mode similar to that used for low dose electron microscopy of radiation sensitive specimens. A higher magnification, in-focus Confirm Mode is used to photograph or confirm the detection of VPs. Setting up the Search Mode by obtaining an out-of-focus image of the specimen in diffraction (K. H. Downing and W. Chiu, private communications) and pre-aligning the image in Search Mode with the image in Confirm Mode facilitates rapid switching between Modes.

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