Exponentiation Bias in Production and Reserves Estimates Made by Use of Exponential-Decline Models

The present paper reports on three sets of experiments exploring the persistence of seeds of oilseed rape (Brassica napus). The first, where known numbers of seeds were buried in September 1991 in two field experiments, demonstrated substantial initial losses of seeds, such that only 0·2 and 3·8% of seeds were still present after 4 months. In these experiments, which were not disturbed by mechanical cultivation, there was little evidence of further decline over the following 13 months. In the second of the two experiments, seeds were then left undisturbed for a further 136 months. A mean of 1·8% of seeds were still present after this period, providing further confirmation of the lack of decline in seed numbers in these undisturbed conditions. In the second pair of experiments, known numbers of seeds of three rape cultivars were broadcast onto plots and then either ploughed into the soil immediately after the start of the experiments, or were exposed to weekly shallow tine cultivation followed by ploughing after 4 weeks. The former created a larger seedbank than the latter. The experiments were then ploughed, annually (Expt 1) or at less frequent intervals (Expt 2); appreciable numbers of seeds survived for 65 months in both. Calculations based on exponential decline curves indicated that 95% seed loss would take 15–39 months, depending on the site, cultivar and initial post-harvest stubble treatment. The third part of the paper is based on more detailed studies of persistence of seeds of six cultivars in Petri dishes and buried in 25 cm pots. This work confirmed that cultivars differed in their persistence, as Apex was confirmed as highly persistent, whereas Rebel was short-lived. There were inconsistencies in the response of cultivar Synergy between the Petri-dish and pot experiment, which need further study. This experiment also reinforced the conclusion of the initial field experiments that little seed loss occurs in the absence of cultivations. Appreciable numbers of rape seeds will persist up to 4 years, in normal cropping conditions and in the absence of cultivation one experiment has confirmed persistence for over 11 years.

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Evaluating the use of ram and suction during prey capture by cichlid fishes

Journal of Experimental Biology ◽

10.1242/jeb.204.17.3039 ◽

2001 ◽

Vol 204 (17) ◽

pp. 3039-3051 ◽

Cited By ~ 26

Author(s):

Peter C. Wainwright ◽

Lara A. Ferry-Graham ◽

Thomas B. Waltzek ◽

Andrew M. Carroll ◽

C. Darrin Hulsey ◽

...

Keyword(s):

Poecilia Reticulata ◽

Prey Capture ◽

Suction Feeding ◽

Predator Species ◽

Cichlid Fishes ◽

Major Constraint ◽

Exponential Decline ◽

Astronotus Ocellatus ◽

Limited Variation ◽

Jaw Protrusion

SUMMARYWe characterized prey-capture strategies in seven species of cichlid fishes representing diverse trophic habits and anticipated feeding abilities. The species examined were Petenia splendida, Cichla ocellaris, Cichlasoma minckleyi, Astronotus ocellatus, Crenicichla geayi, Heros severus (formerly Cichlasoma severum) and Cyprichromis leptosoma. Three individuals per species were filmed with video at 500Hz as they captured live adult Artemia sp. and Poecilia reticulata. For each feeding sequence, we measured the contribution of predator movement towards the prey (i.e. ram) and the movement of prey towards the predator due to suction. The use of ram differed significantly among prey types and predator species, varying as much as sixfold across predator species. High values of ram resulted in high attack velocities. Jaw protrusion contributed as much as 50% to overall ram values in some species, verifying its role in enhancing attack velocity. Suction distance did not vary significantly among species. Diversity in prey-capture behavior was therefore found to reflect differences among species in the strategy used to approach prey. Limited variation in the distance from which prey were sucked into the mouth is interpreted as the result of an expected exponential decline in water velocity with distance from the mouth of the suction-feeding predator. We propose that this relationship represents a major constraint on the distance over which suction feeding is effective for all aquatic-feeding predators.

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Influence of Water Temperature on the Growth Rate of the Landlocked Sea Lamprey (Petromyzon marinus) and the Associated Rate of Host Mortality

Journal of the Fisheries Research Board of Canada ◽

10.1139/f77-197 ◽

1977 ◽

Vol 34 (9) ◽

pp. 1373-1378 ◽

Cited By ~ 24

Author(s):

G. J. Farmer ◽

F. W. H. Beamish ◽

P. F. Lett

Keyword(s):

Growth Rate ◽

Great Lakes ◽

Water Temperature ◽

Growth Rates ◽

Petromyzon Marinus ◽

Sea Lamprey ◽

Instantaneous Growth ◽

Exponential Decline ◽

Influence Of Water ◽

Host Mortality

Groups of sea lampreys (Petromyzon marinus) of 10–90 g initial weight were held at temperatures of 1–20 °C for 30 days and allowed to feed ad lib. on white suckers (Catostomus commersoni). Increases in water temperature and in lamprey size caused the rate of host mortality to increase in agreement with observations that mortality in the Great Lakes is seasonal. Instantaneous growth rates were maximal at 20 °C for lampreys of 10–30 g, the optimal temperature for growth shifting to 15 °C for larger lampreys of 30–90 g. Growth rates were intermediate at 10 °C and lowest at 4 °C for lampreys of all size. Accordingly, host mortality increased with temperature over the 4–20 °C range. At all experimental temperatures, increases in lamprey weight were accompanied by an exponential decline in instantaneous growth rates, a phenomenon also observed for teleosts. Laboratory growth rates at temperatures of 5–15 °C were comparable to rates observed for lampreys in Lake Huron between April and November and agree with the observation that lampreys feed in deeper waters between April and June before moving to warmer, shallower waters during the summer when growth rate increases. Key words: sea lamprey, white sucker, host, temperature, growth, Great Lakes, mortality

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An Age-Related Exponential Decline in the Risk of Multiple Islet Autoantibody Seroconversion During Childhood

10.2337/figshare.13643756 ◽

2021 ◽

Author(s):

Ezio Bonifacio ◽

Andreas Weiß ◽

Christiane Winkler ◽

Markus Hippich ◽

Marian J. Rewers ◽

...

Keyword(s):

Type 1 Diabetes ◽

Confidence Interval ◽

Islet Autoantibodies ◽

Islet Autoimmunity ◽

Islet Autoantibody ◽

Age Related ◽

At Risk Children ◽

Exponential Decline ◽

Design And Methods

Objective. Islet autoimmunity develops prior to clinical type 1 diabetes and includes multiple and single autoantibody phenotypes. The objective was to determine age-related risks of islet autoantibodies that reflect etiology and improve screening for pre-symptomatic type 1 diabetes. Research Design and Methods. The Environmental Determinants of Diabetes in the Young study prospectively followed 8,556 genetically at-risk children at 3–6-month intervals from birth for the development of islet autoantibodies and type 1 diabetes. The age-related change in the risk of developing islet autoantibodies was determined using landmark and regression models. Results. The 5-year risk of developing multiple islet autoantibodies was 4.3% (95% confidence interval, 3.8–4.7) at 7.5 months of age and declined to 1.1% (95% confidence interval, 0.8–1.3) at a landmark age of 6.25 years (P<0.0001). Risk decline was slight or absent in single insulin- and GAD-autoantibody phenotypes. The influence of sex, HLA and other susceptibility genes on risk subsided with increasing age and was abrogated by age six years. Highest sensitivity and positive predictive value of multiple islet autoantibody phenotypes for type 1 diabetes was achieved by autoantibody screening at 2 years and again at 5–7 years of age. Conclusions. The risk of developing islet autoimmunity declines exponentially with age and the influence of major genetic factors on this risk is limited to the first few years of life.

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Importance of the Submerged Zone during Dry Periods to Nitrogen Removal in a Bioretention System

10.20944/preprints202001.0383.v1 ◽

2020 ◽

Author(s):

Kangmao He ◽

Huapeng Qin ◽

Fan Wang ◽

Wei Ding ◽

Yixiang Yin

Keyword(s):

Removal Efficiency ◽

Nitrogen Removal ◽

Early Stage ◽

Nitrogen Concentration ◽

Rainfall Amount ◽

Dry Period ◽

Upward Trend ◽

Bioretention System ◽

N Removal ◽

Exponential Decline

Adding a submerged zone (SZ) is deemed to promote denitrification during dry periods and thus improve NO3--N removal efficiency of a bioretention system. However, few studies had investigated the variation of nitrogen concentration in the SZ during dry periods and evaluated the effect of the variation on nitrogen removal of the bioretention system. Based on the experiment in a mesocosm bioretetion system with SZ, this study investigated the variation of nitrogen concentration of the system under 17 consecutive cycles of wet and dry alternation with varied rainfall amount, influent nitrogen concentration and antecedent dry periods (ADP). The results indicated that (1) during the dry periods, NH4+-N concentrations in SZ showed an exponential decline trend, decreasing by 50% in 12.9 ± 7.3 hours; while NO3--N concentrations showed an inverse S-shape decline trend, decreasing by 50% in 18.8 ± 6.4 hours; (2) during the wet periods, NO3--N concentration in the effluent showed an S-shape upward trend; and at the early stage of the wet periods, the concentration was relatively low and significantly correlated with ADP, while the corresponding volume of the effluent was significantly correlated with the SZ depth; (3) in the whole experiment, the contribution of nitrogen decrease in SZ during dry periods to NH4+-N and NO3--N removal accounted for 12% and 92%, respectively; and the decrease of NO3--N in SZ during the dry period was correlated with the influent concentration in the wet period and the length of the dry period.

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Pi inhibits the SR Ca2+ pump and stimulates pump-mediated Ca2+ leak in rabbit cardiac myocytes

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.2000.279.2.h577 ◽

2000 ◽

Vol 279 (2) ◽

pp. H577-H585 ◽

Cited By ~ 9

Author(s):

G. L. Smith ◽

A. M. Duncan ◽

P. Neary ◽

L. Bruce ◽

F. L. Burton

Keyword(s):

Steady State ◽

Inorganic Phosphate ◽

Time Course ◽

Ventricular Myocytes ◽

Cyclopiazonic Acid ◽

Ruthenium Red ◽

Uptake Capacity ◽

Exponential Decline ◽

Pump Rate ◽

Uptake Process

Measurements of sarcoplasmic reticulum (SR) Ca2+ uptake were made from aliquots of dissociated permeabilized ventricular myocytes using fura 2. Equilibration with 10 mM oxalate ensured a reproducible exponential decline of [Ca2+] from 600 nM to a steady state of 100–200 nM after addition of Ca2+. In the presence of 5 μM ruthenium red, which blocks the ryanodine receptor, the time course of the decline of [Ca2+] can be modeled by a Ca2+-dependent uptake process and a fixed Ca2+leak. Partial inhibition of the Ca2+ pump with 1 μM cyclopiazonic acid or 50 nM thapsigargin reduced the time constant for Ca2+ uptake but did not affect the SR Ca2+leak. Addition of 10 mM inorganic phosphate (Pi) decreased the rate of Ca2+ accumulation by the SR and increased the Ca2+ leak rate. This effect was reversed on addition of 10 mM phosphocreatine. 10 mM Pi had no effect on Ca2+ leak from the SR after complete inhibition of the Ca2+ pump. In conclusion, Pi decreases the Ca2+ uptake capacity of cardiac SR via a decrease in pump rate and an increase in Ca2+ pump-dependent Ca2+ leak.

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Energy Transport, Overshoot, and Mixing in the Atmospheres of Very Cool Stars

Symposium - International Astronomical Union ◽

10.1017/s0074180900133303 ◽

2003 ◽

Vol 210 ◽

pp. 113-125

Author(s):

Hans-Günter Ludwig

Keyword(s):

Energy Transport ◽

Thermal Structure ◽

Stability Boundary ◽

Convective Transport ◽

Gravitational Acceleration ◽

Transport Efficiency ◽

Exponential Decline ◽

Pressure Scale ◽

Complex Chemistry ◽

Convective Overshoot

We constructed hydrodynamical model atmospheres for mid M-type main-, as well as pre-main-sequence objects. Despite the complex chemistry encountered in such cool atmospheres a reasonably accurate representation of the radiative transfer is possible. The detailed treatment of the interplay between radiation and convection in the hydrodynamical models allows to study processes usually not accessible within the framework of conventional model atmospheres. In particular, we determined the efficiency of the convective energy transport, and the efficiency of mixing by convective overshoot. The convective transport efficiency expressed in terms of an equivalent mixing-length parameter amounts to values around ≈ 2 in the optically thick, and ≈ 2.8 in the optically thin regime. The thermal structure of the formally convectively stable layers is little affected by convective overshoot and wave heating, i.e. stays close to radiative equilibrium. Mixing by convective overshoot shows an exponential decline with geometrical distance from the Schwarzschild stability boundary. The scale height of the decline varies with gravitational acceleration roughly as g–1/2, with 0.5 pressure scale heights at log g=5.0.

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Exponential Decline in the Dispersal of Stone Artefacts in Roman Britain: Further Expressions of Trade

Oxford Journal of Archaeology ◽

10.1111/ojoa.12050 ◽

2015 ◽

Vol 34 (1) ◽

pp. 97-108 ◽

Cited By ~ 1

Author(s):

J.R.L. Allen

Keyword(s):

Roman Britain ◽

Exponential Decline

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Thymic involution and rising disease incidence with age

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1714478115 ◽

2018 ◽

Vol 115 (8) ◽

pp. 1883-1888 ◽

Cited By ~ 90

Author(s):

Sam Palmer ◽

Luca Albergante ◽

Clare C. Blackburn ◽

T. J. Newman

Keyword(s):

T Cell ◽

Power Law ◽

Wide Spectrum ◽

Disease Incidence ◽

Thymic Involution ◽

Incidence Data ◽

Age Related ◽

Exponential Decline ◽

Combining Data ◽

Cancer Types

For many cancer types, incidence rises rapidly with age as an apparent power law, supporting the idea that cancer is caused by a gradual accumulation of genetic mutations. Similarly, the incidence of many infectious diseases strongly increases with age. Here, combining data from immunology and epidemiology, we show that many of these dramatic age-related increases in incidence can be modeled based on immune system decline, rather than mutation accumulation. In humans, the thymus atrophies from infancy, resulting in an exponential decline in T cell production with a half-life of ∼16 years, which we use as the basis for a minimal mathematical model of disease incidence. Our model outperforms the power law model with the same number of fitting parameters in describing cancer incidence data across a wide spectrum of different cancers, and provides excellent fits to infectious disease data. This framework provides mechanistic insight into cancer emergence, suggesting that age-related decline in T cell output is a major risk factor.

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