The influence of population density on the number of eggs laid by females of Cardiaspina albitextura (Psyllidae)

1963 ◽  
Vol 11 (2) ◽  
pp. 190 ◽  
Author(s):  
LR Clark
Keyword(s):  
Egg Production ◽  
Adult Stage ◽  
Limiting Factor ◽  
Severe Damage ◽  
Population Densities ◽  
Experimental Conditions ◽  
Nymphal Development ◽  
The Mean ◽  
Peak Abundance ◽  
Oviposition Sites

Field observations and experiments suggest that crowding during the period of nymphal development does not greatly affect the mean number of eggs laid by Cardiaspina albitextura females. Under experimental conditions, crowding in the adult stage on foliage undamaged by nymphs resulted in reduction of the mean number of eggs laid, the supply of favourable food being probably the limiting factor. In association with increase in the number of adults per shoot, mean egg production declined at a progressively decreasing rate. At the highest population densities tested, the mean number of eggs laid per female was approximately one-third to one-fifth of the number laid by uncrowded females. Both at low and high population densities, the mean number of eggs laid per female on previously unoccupied foliage was about twice as high as on foliage which had been occupied previously by numerous other adults of the same psyllid generation. At times of peak abundance in areas of outbreak, the foliage damage caused during the period of nymphal development greatly limits both the quantity of favourable food and the number of oviposition sites available when C. albitextura reaches the adult stage. The experimental results suggest that the crowding of adults which occurs on the small amount of foliage that escapes very severe damage by nymphs contributes towards the observed limitation of egg production. However, the scattered distribution of such foliage and the poor dispersal powers of C. albitextura females probably play a more important part in determining the very low mean number of eggs laid per female reaching the adult stage. It appears that many females fail to find favourable foliage and consequently lay scarcely any eggs.

scholarly journals The Effect of Crowding Upon the Oviposition of Grain-Infesting Insects

1942 ◽  
Vol 19 (3) ◽  
pp. 311-340
Author(s):  
A. C. CROMBIE
Keyword(s):  
Conditioned Medium ◽  
Egg Production ◽  
Mutual Effect ◽  
Conditioned Media ◽  
Depressing Effect ◽  
Experimental Conditions ◽  
Oviposition Sites ◽  
Complete Starvation ◽  
Egg Fertility

The crowding of adults invariably had a depressing effect upon the rate of oviposition in the insects studied here, while egg-fertility was not affected. In unconditioned media, at densities possible in actual populations, the reduction of fecundity was, it appears, entirely a result of competition for the oviposition sites usually for two purposes, viz. oviposition and feeding. That is to say, at such densities the effect of crowding upon oviposition was of a behaviouristic nature. When two species were living in the same environment their mutual effect upon each other's fecundity was more or less dependent upon the degree of identity of the niches for which they were competing. The reduction of fecundity of Rhizopertha by homotypically and heterotypically conditioned media was at first roughly proportional to the degree of conditioning, but after a time the effect of all media was the same. Homo- and hetero-typical conditioning were not radically different in effect. It is believed that conditioned medium operates upon fecundity through ‘poisoning’, and that the effect is upon oviposition rather than, as that of starvation, upon egg-production. When returned to an optimum environment the insects recovered from all the experimental conditions mentioned here: immediately from conditions of overcrowding, more slowly from conditioned media, and more slowly still from complete starvation.

scholarly journals Impact of different pineapple mealybug densities in a peanut crop

2018 ◽  
Vol 44 (1) ◽  
pp. 8
Author(s):  
Carlos Alberto Domingues da Silva ◽  
Eduardo Domingos Vasconcelos ◽  
Raul Porfirio De Almeida
Keyword(s):  
Severe Damage ◽  
Population Densities ◽  
Peanut Crop ◽  
Randomized Design ◽  
The World ◽  
Dysmicoccus Brevipes ◽  
The Mean ◽  
Peanut Cultivars ◽  
Completely Randomized Design ◽  
Pineapple Mealybug

The pineapple mealybug Dysmicoccus brevipes (Hemiptera: Pseudococcidae) is a cosmopolitan and polyphagous species that causes severe damage to peanut crops in many countries around the world. This work was conducted in Campina Grande, Paraíba Sate, Brazil, aiming to assess losses in productivity caused by D. brevipes in a peanut crop. A completely randomized design with five treatments and four replicates was used. Treatments consisted of five mealybug population densities (nymphs and adults) on peanut roots and pods, described as follows: T1 = 0 mealybugs per plant; T2 = 1 to 20 mealybugs per plant; T3 = 21 to 40 mealybugs per plant; T4 = 41 to 80 mealybugs per plant and T5 = more than 80 mealybugs per plant. Roots and pods infested with the pest were observed on 84 % of the peanut plants sampled, ranging from zero to 147.1 individuals per plant. The higher the number of mealybugs per plant, the lower the weight of pod. The mean pod productivities of BR1 peanut cultivars, with the highest and lowest densities of mealybugs per plant were 1,695 and 3,290 kg per ha, respectively. Fields heavily infested with D. brevipes risk significant losses due to the enormous capacity of this organism for causing damage.

The effect of mild inbreeding in two lines of White Leghorn

1962 ◽  
Vol 13 (2) ◽  
pp. 362 ◽  
Author(s):  
JA Morris
Keyword(s):  
Egg Production ◽  
Adult Stage ◽  
Random Mating ◽  
Continuous Selection ◽  
Differential Sensitivity ◽  
Time Of Death ◽  
White Leghorn ◽  
The Mean ◽  
Selection For ◽  
June July

The reaction of two flocks of White Leghorn to slow inbreeding has been examined. One flock, the M line, has been subject to continuous selection for egg production or an associated character since 1947, and the other, the C line, has been propagated by means of random mating without artificial selection for a corresponding period. Mean inbreeding, as measured by Wright's coefficient (F), increased steadily in both flocks to reach a maximum of 25.1% in the M line and 16.2% in the C line. Significant intra-year regressions of survivors' production (72 weeks), hatchability of fertile eggs, and egg production during the winter months of June–July, on computed F values, were observed for both lines. In addition, significant regressions for the 72-week production index, age at first egg, and pauses during June–July were observed for the M line. Viability of chickens, both during early rearing (hatching date to 3½ weeks of age) and during adult stage (approximately 20 weeks to 72 weeks of age), was not affected by small changes in degree of inbreeding. Intra-year regressions on F of age at death and production up to time of death were non-significant for both lines. Highly significant differences between yearly regressions of egg production, and pauses during the two winter months, on F values were observed. These differences could indicate a differential sensitivity of response to inbreeding associated with seasonal adversity. It was not possible to substantiate the existence of a differential response to a stress factor when mortality during a severe heat wave was examined, as the mean computed F value of birds dying was not significantly greater than the corresponding F value of survivors. The stress was reasonably severe, as 15.4% of all birds died within a couple of days.

Articulatory Behavior Pre and Post Full-Mouth Tooth Extraction and Alveoloplasty

1980 ◽  
Vol 23 (3) ◽  
pp. 630-645 ◽  
Author(s):  
Gerald Zimmermann ◽  
J.A. Scott Kelso ◽  
Larry Lander
Keyword(s):  
Control Subject ◽  
High Speed ◽  
Tooth Extraction ◽  
Kinematic Parameters ◽  
Experimental Conditions ◽  
Mean Values ◽  
Articulatory Movements ◽  
The Mean ◽  
Experimental Subjects ◽  
Normal Speech

High speed cinefluorography was used to track articulatory movements preceding and following full-mouth tooth extraction and alveoloplasty in two subjects. Films also were made of a control subject on two separate days. The purpose of the study was to determine the effects of dramatically altering the structural dimensions of the oral cavity on the kinematic parameters of speech. The results showed that the experimental subjects performed differently pre and postoperatively though the changes were in different directions for the two subjects. Differences in both means and variabilities of kinematic parameters were larger between days for the experimental (operated) subjects than for the control subject. The results for the Control subject also showed significant differences in the mean values of kinematic variables between days though these day-to-day differences could not account for the effects found pre- and postoperatively. The results of the kinematic analysis, particularly the finding that transition time was most stable over the experimental conditions for the operated subjects, are used to speculate about the coordination of normal speech.

scholarly journals O15 Using a smartphone app to characterise and quantify skin colour changes in Raynaud's attacks

Rheumatology ◽  
2021 ◽  
Vol 60 (Supplement_1) ◽  
Author(s):  
Graham Dinsdale ◽  
Joanne Manning ◽  
Ariane Herrick ◽  
Mark Dickinson ◽  
Christopher Taylor
Keyword(s):  
Mobile Phone ◽  
Strong Association ◽  
Colour Change ◽  
Objective Measure ◽  
Skin Colour ◽  
Smartphone App ◽  
Limiting Factor ◽  
Bhattacharyya Distance ◽  
Automated Method ◽  
The Mean

Abstract Background/Aims  The lack of objective outcome measures for Raynaud's phenomenon (RP) has been a major limiting factor in development of effective treatments. At present, the Raynaud's Condition Score (RCS) is the only validated outcome measure, and is highly subjective. Mobile phone technology could provide a way forward. We have developed a smartphone app for RP monitoring that guides the patient through the process of capturing images of their hands during RP episodes, as well as capturing other data through post-attack and daily questionnaires. One of the objectives of our research programme (reported here) was to compare digital image (photographic) parameters to the RCS. Methods  40 patients with RP (8 with primary RP, 32 with RP secondary to systemic sclerosis) were recruited (40 female, median age (range): 57 years (25-74), median (range) duration of RP symptoms: 17 (0-53) years). Patients were given a smartphone handset with a pre-installed Raynaud’s Monitoring app and were trained on how to use it/take usable photographs. They were then asked to take photographs of RP attacks over a 14 day period and also to record the RCS for each episode. The app specifically prompts the patient to take a picture of their hand every minute during an attack, until confirmation is given that the attack is complete. At a 2nd visit, the handsets, images, and data were collected for analysis. The mean colour change during each RP attack was quantified (semi-automated method) by the Bhattacharyya distance (BD) in colour space between a region of interest (e.g. a section of a digit) and a control region (dorsal hand). BD was then compared to the RCS using ANOVA, after controlling for patient variability in the range of RCS values used by each patient. Results  A total of 3,030 images were collected, describing 229 RP attacks. The median RCS reported was 6 (inter-quartile range [IQR]: 4), while the median for BD was 5.6 (IQR 3.2). ANOVA showed that measured values of the mean image BD were significantly different when different values of RCS were recorded by the patient (p < 0.001), i.e. attacks where patients selected different values of RCS had significantly different values of BD. Across all attacks/patients the F-value from ANOVA for RCS was 76.2, suggesting that the variation in BD for different values of RCS is much greater than the variation in BD for any one value of RCS. Conclusion  Patients successfully used a smartphone app to collect photographs and data during episodes of RP. A strong association was found between skin colour change (via BD) and the gold-standard RCS. Mobile phone-documented colour change therefore has potential as an objective measure of RP. Further validation work is now required, as well as studies examining sensitivity to change. Disclosure  G. Dinsdale: None. J. Manning: None. A. Herrick: None. M. Dickinson: None. C. Taylor: None.

scholarly journals Comparative investigation of lasing and amplification performance in cryogenic Yb:YLF systems

2021 ◽  
Vol 127 (3) ◽  
Author(s):  
Umit Demirbas ◽  
Martin Kellert ◽  
Jelto Thesinga ◽  
Yi Hua ◽  
Simon Reuter ◽  
...  
Keyword(s):  
Continuous Wave ◽  
Estimation Method ◽  
Laser Cavity ◽  
Comparative Investigation ◽  
Limiting Factor ◽  
Experimental Conditions ◽  
Temperature Estimation ◽  
Transverse Temperature ◽  
First Time

AbstractWe present detailed experimental results with cryogenic Yb:YLF gain media in rod-geometry. We have comparatively investigated continuous-wave (cw) lasing and regenerative amplification performance under different experimental conditions. In the cw lasing experiments effect of crystal doping, cw laser cavity geometry and pump wavelength on lasing performance were explored. Regenerative amplification behavior was analyzed and the role of depolarization losses on performance was investigated. A recently developed temperature estimation method was also employed for the first time in estimating average crystal temperature under lasing conditions. It is shown that the thermal lens induced by transverse temperature gradients is the main limiting factor and strategies for future improvements are discussed. To the best of our knowledge, the achieved results in this study (375 W in cw, and 90 W in regenerative amplification) are the highest average powers ever obtained from this system via employing the broadband E//a axis.

scholarly journals Comparison of Bite Force in Patients After Treatment of Mandibular Fractures With 3-Dimensional Locking Miniplate and Standard Miniplates

2019 ◽  
Vol 1 (1) ◽  
pp. 7-10
Author(s):  
Gaurav Singh ◽  
Madan Mishra ◽  
Amit Gaur ◽  
Dhritiman Pathak
Keyword(s):  
Treatment Strategies ◽  
Bite Force ◽  
Mandibular Fractures ◽  
Time Intervals ◽  
Experimental Conditions ◽  
3 Dimensional ◽  
The Mean ◽  
Group 2 ◽  
Drilling Conditions ◽  
Group 1

Background: Fractures of the mandible can be studied and described in anatomic terms, functional considerations, treatment strategies, and outcome measures. The performance of any fixation system depends on multiple factors including plate adaptation, screw placement, bone quality, drilling conditions, and postoperative patient compliance. Bite force assesses masticatory muscle function under clinical and experimental conditions. Method: 30 patients with isolated, noncomminuted mandibular fractures were randomly divided into two equal groups. Group 1 patients were treated using 3-dimensional locking miniplates and group 2 patients were treated with standard miniplates. The bite forces were recorded at definite time intervals: preoperatively, and second week, sixth week, third month, and sixth month postoperatively. Result: At 6 weeks postoperative, 3 month postoperative, and 6 month postoperative, the mean bite force was found to be significantly higher among group 1 patients as compared to those in group 2 in all the sites. While at 2 week postoperative, the mean bite force was found to be significantly higher in Group 2 as compared to Group 1 at incisor region. Conclusion: The overall results of the present study show better performance in bite force for the 3-dimensional locking miniplate when compared with standard miniplates.

An Examination of Language Samples Obtained under Three Experimental Conditions

1982 ◽  
Vol 13 (2) ◽  
pp. 121-128 ◽  
Author(s):  
Louise D. Stalnaker ◽  
Nancy A. Creaghead
Keyword(s):  
Preschool Children ◽  
Head Start ◽  
Experimental Conditions ◽  
Semantic Relationships ◽  
Three Samples ◽  
The Mean ◽  
Mean Length Of Utterance ◽  
Language Sample

Language samples were obtained from 12 Head Start preschool children under the following three experimental conditions: Condition I, Retelling a Story with Toys; Condition II, Playing with Toys; Condition III, Toys with Questions. The quantity and quality of the three samples gathered from each child were compared by analyzing the total number of utterances, the proportion of the total utterances which were sentence fragments, the number of transformations and adverbial expansions, the number of different semantic relationships, and the mean length of utterance (MLU). Results indicated that retelling a story produced the largest MLU, but toys and questions produced more utterances. These findings indicated that questioning children does not inhibit their language and asking them to retell a story may be a fruitful approach to use when gathering a language sample.

Biosorption of uranium(VI) from aqueous solution by biomass of brown algae Laminaria japonica

2014 ◽  
Vol 70 (1) ◽  
pp. 136-143 ◽  
Author(s):  
K. Y. Lee ◽  
K. W. Kim ◽  
Y. J. Baek ◽  
D. Y. Chung ◽  
E. H. Lee ◽  
...  
Keyword(s):  
Particle Size ◽  
Brown Algae ◽  
Activated Carbons ◽  
Laminaria Japonica ◽  
Limiting Factor ◽  
Stable Operation ◽  
Experimental Conditions ◽  
Wastewater Treatment Process ◽  
Radioactive Wastewater ◽  
Ionic Diffusivity

The uranium(VI) adsorption efficiency of non-living biomass of brown algae was evaluated in various adsorption experimental conditions. Several different sizes of biomass were prepared using pretreatment and surface-modification steps. The kinetics of uranium uptake were mainly dependent on the particle size of the prepared Laminaria japonica biosorbent. The optimal particle size, contact time, and injection amount for the stable operation of the wastewater treatment process were determined. Spectroscopic analyses showed that uranium was adsorbed in the porous inside structure of the biosorbent. The ionic diffusivity in the biomass was the dominant rate-limiting factor; therefore, the adsorption rate was significantly increased with decrease of particle size. From the results of comparative experiments using the biosorbents and other chemical adsorbents/precipitants, such as activated carbons, zeolites, and limes, it was demonstrated that the brown algae biosorbent could replace the conventional chemicals for uranium removal. As a post-treatment for the final solid waste reduction, the ignition treatment could significantly reduce the weight of waste biosorbents. In conclusion, the brown algae biosorbent is shown to be a favorable adsorbent for uranium(VI) removal from radioactive wastewater.

THE IMMATURE STAGES OF PTYCHOPTERA LENIS LENIS (DIPTERA: PTYCHOPTERIDAE) WITH NOTES ON THEIR BIOLOGY

1973 ◽  
Vol 105 (8) ◽  
pp. 1091-1099 ◽  
Author(s):  
I. D. Hodkinson
Keyword(s):  
Life Cycle ◽  
Water Depth ◽  
Adult Stage ◽  
Atmospheric Oxygen ◽  
Adult Emergence ◽  
Fourth Instar ◽  
Immature Stages ◽  
Experimental Conditions ◽  
Marginal Areas ◽  
Pharate Adult

AbstractThe four larval instars and the pupa of Ptychoptera lenis lenis Osten Sacken are described. Instars 2 to 4 are very similar morphologically but instar 1 is markedly different. Both a pharate pupal and a pharate adult stage were observed. Larvae are found in stagnant marginal areas of ponds where water depth does not exceed 4 cm and where benthic deposits of plant detritus exceed 8 cm. Fourth instar larvae, under experimental conditions, survived up to 45 days without contact with atmospheric oxygen but development was arrested. P. lenis has a 1 year life cycle with an extended adult emergence season from late May to the end of July.

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