scholarly journals Long seed dispersal distances by an inquisitive flightless rail ( Gallirallus australis ) are reduced by interaction with humans

2019 ◽  
Vol 6 (8) ◽  
pp. 190397
Author(s):  
Joanna K. Carpenter ◽  
Colin F. J. O'Donnell ◽  
Elena Moltchanova ◽  
Dave Kelly
Keyword(s):  
Seed Dispersal ◽  
Mechanistic Model ◽  
Human Interaction ◽  
Time Data ◽  
Seed Retention ◽  
Function Loss ◽  
The Mean ◽  
Human Use ◽  
Dispersal Distances ◽  
Seed Retention Time

Human presence is becoming increasingly ubiquitous, but the influence this has on the seed dispersal services performed by frugivorous animals is largely unknown. The New Zealand weka ( Gallirallus australis ) is an inquisitive flightless rail that frequently congregates in areas of high human use. Weka are important seed dispersers, yet the seed dispersal services they provide are still poorly understood. We estimated seed dispersal distances of weka for two plant species ( Prumnopitys ferruginea and Elaeocarpus dentatus ) and tested how human interaction affected these dispersal distances. We estimated weka seed dispersal distances by combining GPS data from 39 weka over three sites with weka seed retention time data in a mechanistic model. The mean seed retention times were extremely long (38–125 h). Weka were highly effective dispersers, dispersing 93–96% of seeds away from parent canopies, and 1% of seeds over 1 km. However, we found evidence of a significant human impact on the seed dispersal distances of weka, with birds occupying areas of high human use performing 34.8–40.9% shorter distances than their more remote counterparts. This represents an example of cryptic function loss, where although weka are still present in the ecosystem, their seed dispersal services are impaired by human interaction.

scholarly journals Extremely long-distance seed dispersal by an overfished Amazonian frugivore

2011 ◽  
Vol 278 (1723) ◽  
pp. 3329-3335 ◽  
Author(s):  
Jill T. Anderson ◽  
Tim Nuttle ◽  
Joe S. Saldaña Rojas ◽  
Thomas H. Pendergast ◽  
Alexander S. Flecker
Keyword(s):  
Seed Dispersal ◽  
Mechanistic Model ◽  
Long Distance ◽  
Seed Dispersal Effectiveness ◽  
Colossoma Macropomum ◽  
Seed Retention ◽  
Dispersal Distances ◽  
Viable Seeds ◽  
Almost All ◽  
Dispersal Effectiveness

Throughout Amazonia, overfishing has decimated populations of fruit-eating fishes, especially the large-bodied characid, Colossoma macropomum . During lengthy annual floods, frugivorous fishes enter vast Amazonian floodplains, consume massive quantities of fallen fruits and egest viable seeds. Many tree and liana species are clearly specialized for icthyochory, and seed dispersal by fish may be crucial for the maintenance of Amazonian wetland forests. Unlike frugivorous mammals and birds, little is known about seed dispersal effectiveness of fishes. Extensive mobility of frugivorous fish could result in extremely effective, multi-directional, long-distance seed dispersal. Over three annual flood seasons, we tracked fine-scale movement patterns and habitat use of wild Colossoma , and seed retention in the digestive tracts of captive individuals. Our mechanistic model predicts that Colossoma disperses seeds extremely long distances to favourable habitats. Modelled mean dispersal distances of 337–552 m and maximum of 5495 m are among the longest ever reported. At least 5 per cent of seeds are predicted to disperse 1700–2110 m, farther than dispersal by almost all other frugivores reported in the literature. Additionally, seed dispersal distances increased with fish size, but overfishing has biased Colossoma populations to smaller individuals. Thus, overexploitation probably disrupts an ancient coevolutionary relationship between Colossoma and Amazonian plants.

scholarly journals How far might plant-eating dinosaurs have moved seeds?

2021 ◽  
Vol 17 (1) ◽  
pp. 20200689
Author(s):  
George L. W. Perry
Keyword(s):  
Seed Dispersal ◽  
Body Mass ◽  
Dispersal Distance ◽  
Movement Speed ◽  
Gut Contents ◽  
Allometric Relationship ◽  
Seed Retention ◽  
Dispersal Distances ◽  
Seed Retention Time ◽  
Seed Dispersal Distance

Fossilized gut contents suggest that seeds consumed by dinosaurs may have remained intact in their stomachs, and since seed dispersal distance increases with body-mass in extant vertebrates, dinosaurs may have moved seeds long distances. I simulated seed dispersal by dinosaurs across body-masses from 1 × 10 1 to 8 × 10 4 kg using allometric random walk models, informed by relationships between (i) body-mass and movement speed, and (ii) body-mass and seed retention time. Seed dispersal distances showed a hump-shaped relationship with body-mass, reflecting the allometric relationship between maximum movement speed and body-mass. Across a range of assumptions and parameterizations, the simulations suggest that plant-eating dinosaurs could have dispersed seeds long distances.

Modeling Within-Person Variance in Reaction Time Data of Older Adults

GeroPsych ◽  
2011 ◽  
Vol 24 (4) ◽  
pp. 169-176 ◽  
Author(s):  
Philippe Rast ◽  
Daniel Zimprich
Keyword(s):  
Reaction Time ◽  
Cognitive Aging ◽  
Reaction Times ◽  
Reaction Time Task ◽  
Reaction Time Data ◽  
Scale Model ◽  
Time Data ◽  
Time Task ◽  
The Mean ◽  
Second Wave

In order to model within-person (WP) variance in a reaction time task, we applied a mixed location scale model using 335 participants from the second wave of the Zurich Longitudinal Study on Cognitive Aging. The age of the respondents and the performance in another reaction time task were used to explain individual differences in the WP variance. To account for larger variances due to slower reaction times, we also used the average of the predicted individual reaction time (RT) as a predictor for the WP variability. Here, the WP variability was a function of the mean. At the same time, older participants were more variable and those with better performance in another RT task were more consistent in their responses.

scholarly journals A mechanistic model for secondary seed dispersal by wind and its experimental validation

2005 ◽  
Vol 93 (5) ◽  
pp. 1017-1028 ◽  
Author(s):  
FRANK M. SCHURR ◽  
WILLIAM J. BOND ◽  
GUY F. MIDGLEY ◽  
STEVEN I. HIGGINS
Keyword(s):  
Seed Dispersal ◽  
Experimental Validation ◽  
Mechanistic Model ◽  
Secondary Seed Dispersal

Crustal structure in the Transvaal*

1956 ◽  
Vol 46 (4) ◽  
pp. 293-316
Author(s):  
P. G. Gane ◽  
A. R. Atkins ◽  
J. P. F. Sellschop ◽  
P. Seligman
Keyword(s):  
Travel Time ◽  
Crustal Structure ◽  
Time Data ◽  
Lower Velocity ◽  
Travel Time Data ◽  
The Mean

abstract Travel-time data are given at 25 km. intervals between 50 and 500 km. for traverses west, south, east, and north of Johannesburg. These derive from numerous seismograms of Witwatersrand earth tremors taken by means of a triggering technique. The only phases considered to be consistent are those mentioned below, and few signs of a change of velocity with depth were discovered. There were no great differences in the results for the various directions, and the mean results were: P 1 = + 0.24 + Δ / 6.18 sec . S 1 = + 0.37 + Δ / 3.66 sec . P n = + 7.61 + Δ / 8.27 sec . S n = + 11.4 + Δ / 4.73 sec . which give crustal depths of 35.1 and 33.3 km. from P and S data respectively. These depths include about 1.3 km. of superficial material of lower velocity.

scholarly journals DEVELOPMENT AND VALIDATION OF BIOANALYTICAL HPLC METHOD FOR SIMULTANEOUS ESTIMATION OF CILNIDIPINE AND NEBIVOLOL IN HUMAN PLASMA

2017 ◽  
Vol 9 (10) ◽  
pp. 253
Author(s):  
Aruna G. ◽  
Bharathi K ◽  
Kvsrg Prasad
Keyword(s):  
Human Plasma ◽  
Analytical Method ◽  
Internal Standard ◽  
Hplc Method ◽  
Pharmacokinetic Parameters ◽  
Simultaneous Estimation ◽  
Time Data ◽  
Bioanalytical Method Validation ◽  
Limit Of Quantitation ◽  
The Mean

Objective: To develop and validate a modified isocratic reversed-phase high performance liquid chromatographic (RP-HPLC) method for determination of cilnidipine and nebivolol in human plasma to be used for pharmacokinetic studies.Methods: The drug was extracted from plasma samples by direct protein precipitation technique using acetonitrile. Amlodipine was used as internal standard (IS). Samples were analyzed on BDS C18 column (250 x 4.6 mm, 5 µm), applying ortho phosphoric acid (0.1%): Acetonitrile, at a ratio of 45:55 v/v in isocratic mode as a mobile phase at a flow rate of 1 ml/min to attain adequate resolution. Separations were performed at room temperature and monitored at a wavelength of 260 nm after injection of 50μl samples into the HPLC system. The analytical method was validated according to FDA bioanalytical method validation guidance. The method was applied for pharmacokinetic study of cilnidipine and nebivolol tablets-10 mg and 5 mg were administered as a single dose to 6 healthy male rabbits under fasting condition. Twelve blood samples were withdrawn from each rabbit over 24 h periods. From the plasma concentration-time data of each individual, the pharmacokinetic parameters; Cmax, Tmax, AUC0-t and AUC0-∞ were calculated.Results: A peak area was obtained for cilnidipine and nebivolol at 3.943 and 4.719 min retention time respectively. Linearity was established at a concentration range of 0.20-20 μg/ml (r2=0.999, n=8) for cilnidipine and 0.02-2 μg/ml (r2=0.999, n=8) for nebivolol. The lower limit of quantitation (LLOQ) was identifiable and reproducible at 0.2μg/ml for cilnidipine and 0.02 μg/ml for nebivolol. The coefficients of variation (%cv) of the intra-day and inter-day precision of cilnidipine at 600, 1000 and 1600ng/ml levels were found to be 6.90%, 6.19%, 5.22%; and 7.74%, 6.54%, 5.77%, respectively, which are lower than the accepted criteria limits (15-20 %). The mean recovery (%) cilnidipine at 600, 1000, and 1600ng/ml was found to be 101.03%, 99.27% and 104.87%, and for nebivolol 60, 100, and 160 ng/ml was found to be 106.13%, 107.03% and 98.06% respectively. Stability at different conditions and in autosampler was also established. The mean pharmacokinetic parameters; Cmax, Tmax, AUC0-t and AUC0-∞ were 6 ng/ml, 2 hr, 96.76 mg. hr/ml, 63.45 mg. hr/ml for cilnidipine and 5.8ng/ml, 2hr, 74.78 mg. hr/ml, 100.25 mg. hr/ml for nebivolol respectively.Conclusion: The present analytical method was found to be specific, sensitive, accurate and precise for quantification of cilnidipine and nebivolol in human plasma. It can be successively applied for pharmacokinetics, bioavailability and bioequivalence studies.

Crashworthiness of Aluminum Extrusion Under Simulated Service Life Heat Exposure

2004 ◽  
Author(s):  
Ridha Baccouche ◽  
Andy Sherman ◽  
Susan Ward ◽  
David Wagner ◽  
Craig Miller ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Service Life ◽  
Energy Management ◽  
Heat Exposure ◽  
Thermal Exposure ◽  
Heat Treatments ◽  
Aluminum Extrusion ◽  
Time Data ◽  
The Mean ◽  
Alloy Properties

An investigation of the service life aging and heat exposure effects on extruded aluminum alloy properties and structural crashworthiness has been conducted. This research, part of a broader program, consists of investigating five aluminum alloy extrusions each of which is subjected to two heat treatments. The aluminum extrusion investigated are 6063T6, 6061T6, 6260T6, 6014T6, and 7129T6. The two heat treatments are 177°C for 30 minutes and 200°C for 24 hours. The 200°C/24 hours treatment represents an upper limit thermal exposure i.e. components adjacent to exhaust pipes and manifolds. The 200°C heat treatment was applied in addition to the 177°C for 30 minutes. All specimens were subjected to the reference 177°C for 30 minutes treatment. These ten crash members were subjected to dynamic axial crashing at a target speed of 40 kph (25 mph). Force-time data was collected and responses were plotted for all tests. Force-displacement responses were then integrated for the crash energy management and mean axial crash load for each of the aluminum extruded crash members. Bar charts were then generated to describe the crash loads and energy management behaviors of the various aluminum alloys and associated heat treatments. Service life simulated heat exposure was found to effect the mean crash load and crash energy management of the aluminum structural crash members. The heat exposure effects on the crashworthiness of the extruded aluminum members ranged from a reduction of 10% to over 20% in the mean crash load and crash energy management with highest variation observed with the 6260T6 aluminum extrusion.

Lung water measurements with the mean transit time approach

1985 ◽  
Vol 59 (3) ◽  
pp. 673-683 ◽  
Author(s):  
R. M. Effros
Keyword(s):  
Transit Time ◽  
Mean Transit Time ◽  
Tissue Perfusion ◽  
Time Data ◽  
Lung Water ◽  
Thermal Signal ◽  
The Mean ◽  
Points Of View ◽  
Vascular Obstruction ◽  
Pulmonary Vascular Obstruction

The potential usefulness and limitations of the double-indicator mean transit time approach for measuring lung water are evaluated from both theoretical and empirical points of view. It is concluded that poor tissue perfusion is the most serious factor that can compromise the reliability of this approach. Replacement of the conventional water isotopes with a thermal signal enhances indicator delivery to ischemic areas but the diffusion of heat is not sufficiently rapid to permit measurements of water in macroscopic collections of fluid which remain unperfused. The frequency of pulmonary vascular obstruction in patients with pulmonary edema related to lung injury suggests that interpretation of transit time data will be complicated by uncertainties concerning perfusion. Thermal-dye measurements of lung water may prove more helpful in situations where pulmonary blood flow remains relatively uniform.

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