scholarly journals Comparison principles and applications to mathematical modelling of vegetal meta-communities

2021 ◽  
Vol 4 (5) ◽  
pp. 1-17
Author(s):  
Gauthier Delvoye ◽  
◽  
Olivier Goubet ◽  
Frédéric Paccaut ◽  
Keyword(s):  
Hydrodynamic Limit ◽  
Exchange Process ◽  
Large Population ◽  
Extinction Time ◽  
Step Method ◽  
Forest Patches ◽  
Comparison Principles ◽  
Reproduction Process ◽  
The Mean ◽  
Large Population Limit

<abstract><p>This article partakes of the PEGASE project the goal of which is a better understanding of the mechanisms explaining the behaviour of species living in a network of forest patches linked by ecological corridors (hedges for instance). Actually we plan to study the effect of the <italic>fragmentation</italic> of the habitat on biodiversity. A simple neutral model for the evolution of abundances in a vegetal metacommunity is introduced. Migration between the communities is explicitely modelized in a deterministic way, while the reproduction process is dealt with using Wright-Fisher models, independently within each community. The large population limit of the model is considered. The hydrodynamic limit of this split-step method is proved to be the solution of a partial differential equation with a deterministic part coming from the migration process and a diffusion part due to the Wright-Fisher process. Finally, the diversity of the metacommunity is adressed through one of its indicators, the mean extinction time of a species. At the limit, using classical comparison principles, the exchange process between the communities is proved to slow down extinction. This shows that the existence of corridors seems to be good for the biodiversity.</p></abstract>

scholarly journals Planetary Nebulae in M31: Abundances, and comparison with bright Planetary Nebulae in the LMC

1997 ◽  
Vol 180 ◽  
pp. 475-476
Author(s):  
M. G. Richer ◽  
G. Stasińska ◽  
M. L. McCall
Keyword(s):  
Planetary Nebula ◽  
Luminosity Function ◽  
Large Population ◽  
Wavelength Region ◽  
Planetary Nebulae ◽  
Surprising Result ◽  
Population Synthesis ◽  
Abundance Distribution ◽  
Wide Range ◽  
The Mean

We have obtained spectra of 28 planetary nebulae in the bulge of M31 using the MOS spectrograph at the Canada-France-Hawaii Telescope. Typically, we observed the [O II] λ3727 to He I λ5876 wavelength region at a resolution of approximately 1.6 å/pixel. For 19 of the 21 planetary nebulae whose [OIII]λ5007 luminosities are within 1 mag of the peak of the planetary nebula luminosity function, our oxygen abundances are based upon a measured [OIII]λ4363 intensity, so they are based upon a measured electron temperature. The oxygen abundances cover a wide range, 7.85 dex < 12 + log(O/H) < 9.09 dex, but the mean abundance is surprisingly low, 12 + log(O/H)–8.64 ± 0.32 dex, i.e., roughly half the solar value (Anders & Grevesse 1989). The distribution of oxygen abundances is shown in Figure 1, where the ordinate indicates the number of planetary nebulae with abundances within ±0.1 dex of any point on the x-axis. The dashed line indicates the mean abundance, and the dotted lines indicate the ±1 σ points. The shape of this abundance distribution seems to indicate that the bulge of M31 does not contain a large population of bright, oxygen-rich planetary nebulae. This is a surprising result, for various population synthesis studies (e.g., Bica et al. 1990) have found a mean stellar metallicity approximately 0.2 dex above solar. This 0.5 dex discrepancy leads one to question whether the mean stellar metallicity is as high as the population synthesis results indicate or if such metal-rich stars produce bright planetary nebulae at all. This could be a clue concerning the mechanism responsible for the variation in the number of bright planetary nebulae observed per unit luminosity in different galaxies (e.g., Hui et al. 1993).

scholarly journals No correlation was observed between vitamin D levels and disability of patients with multiple sclerosis between latitudes 18° and 30° South

2017 ◽  
Vol 75 (1) ◽  
pp. 3-8 ◽  
Author(s):  
Yara Dadalti Fragoso ◽  
Tarso Adoni ◽  
Soniza Vieira Alves-Leon ◽  
Samira L. Apostolos-Pereira ◽  
Walter Oleschko Arruda ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Vitamin D ◽  
Large Population ◽  
Serum Vitamin ◽  
Serum Levels ◽  
Serum Vitamin D ◽  
Control Subjects ◽  
Vitamin D Levels ◽  
The Mean ◽  
25 Oh Vitamin D

ABSTRACT Objective: Vitamin D has taken center stage in research and treatment of multiple sclerosis (MS). The objective of the present study was to assess the serum vitamin D levels of a large population of patients with MS and controls living in a restricted tropical area. Methods: Data from 535 patients with MS and 350 control subjects were obtained from 14 cities around the Tropic of Capricorn. Results: The mean serum 25-OH vitamin D level was 26.07 ± 10.27 ng/mL for the control subjects, and 28.03 ± 12.19 ng/mL for patients with MS. No correlation was observed between vitamin D levels and the disability of patients over the disease duration. Conclusion: At least for the region around the Tropic of Capricorn, serum levels of vitamin D typically are within the range of 20 to 30 ng/mL for controls and patients with MS.

scholarly journals Protein Intake Estimated from Brief-Type Self-Administered Diet History Questionnaire and Urinary Urea Nitrogen Level in Adolescents

Nutrients ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 319 ◽  
Author(s):  
Masayuki Okuda ◽  
Keiko Asakura ◽  
Satoshi Sasaki
Keyword(s):  
Protein Intake ◽  
Low Cost ◽  
Large Population ◽  
Urinary Biomarkers ◽  
School Students ◽  
Urea Nitrogen ◽  
Diet History Questionnaire ◽  
Diet History ◽  
The Mean ◽  
Urine Specimens

Our aim was to assess the validity of the brief-type self-administered diet history questionnaire (BDHQ15y) to estimate the protein intake in 248 Japanese secondary school students (mean age = 14.2 years), using urinary biomarkers as references. Participants provided three samples of overnight urine for measurement of urea nitrogen and creatinine levels, underwent anthropometric measurements, and answered the questionnaires. Additionally, 58 students provided 24-h urine specimens. A significant correlation was observed between excretion of urea nitrogen in overnight and 24-h urine specimens (ρ = 0.527; p < 0.001), with biases ≤5.8%. The mean daily protein intake estimated from urinary biomarkers was 76.4 ± 20.4 g/d in males and 65.4 ± 16.9 g/d in females, and the mean protein intake estimated from the BDHQ15y (PRTbdhq) was 89.3 ± 33.7 g/d in males and 79.6 ± 24.6 g/d in females. Crude and energy-adjusted coefficients of correlation between PRTbdhq and protein intake estimated from urinary biomarkers were 0.205 (p = 0.001; 0.247 for males and 0.124 for females), and 0.204 (p = 0.001; 0.302 for males and 0.109 for females), respectively. The BDHQ15y is a low-cost tool to assess protein intake of a large population, instead of a weakness of overestimation.

scholarly journals Use of Alternative Carrier Materials in AOAC Official MethodSM 2008.05, Efficacy of Liquid Sporicides Against Spores of Bacillus subtilis on a Hard, Nonporous Surface, Quantitative Three-Step Method

2010 ◽  
Vol 93 (1) ◽  
pp. 259-276 ◽  
Author(s):  
Stephen F Tomasino ◽  
Vipin K Rastogi ◽  
Lalena Wallace ◽  
Lisa S Smith ◽  
Martin A Hamilton ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Ceramic Tile ◽  
Step Method ◽  
Porous Carrier ◽  
Pine Wood ◽  
Log Reduction ◽  
Microcentrifuge Tube ◽  
Carrier Materials ◽  
Aoac Official ◽  
The Mean

Abstract The quantitative Three-Step Method (TSM) for testing the efficacy of liquid sporicides against spores of Bacillus subtilis on a hard, nonporous surface (glass) was adopted as AOAC Official MethodSM 2008.05 in May 2008. The TSM uses 5 5 1 mm coupons (carriers) upon which spores have been inoculated and which are introduced into liquid sporicidal agent contained in a microcentrifuge tube. Following exposure of inoculated carriers and neutralization, spores are removed from carriers in three fractions (gentle washing, fraction A; sonication, fraction B; and gentle agitation, fraction C). Liquid from each fraction is serially diluted and plated on a recovery medium for spore enumeration. The counts are summed over the three fractions to provide the density (viable spores per carrier), which is log10-transformed to arrive at the log density. The log reduction is calculated by subtracting the mean log density for treated carriers from the mean log density for control carriers. This paper presents a single-laboratory investigation conducted to evaluate the applicability of using two porous carrier materials (ceramic tile and untreated pine wood) and one alternative nonporous material (stainless steel). Glass carriers were included in the study as the reference material. Inoculated carriers were evaluated against three commercially available liquid sporicides (sodium hypochlorite, a combination of peracetic acid and hydrogen peroxide, and glutaraldehyde), each at two levels of presumed efficacy (medium and high) to provide data for assessing the responsiveness of the TSM. Three coupons of each material were evaluated across three replications at each level; three replications of a control were required. Even though all carriers were inoculated with approximately the same number of spores, the observed counts of recovered spores were consistently higher for the nonporous carriers. For control carriers, the mean log densities for the four materials ranged from 6.63 for wood to 7.14 for steel. The pairwise differences between mean log densities, except for glass minus steel, were statistically significant (P &lt; 0.001). The repeatability standard deviations (Sr) for the mean control log density per test were similar for the four materials, ranging from 0.08 for wood to 0.13 for tile. Spore recovery from the carrier materials ranged from approximately 20 to 70: 20 (pine wood), 40 (ceramic tile), 55 (glass), and 70 (steel). Although the percent spore recovery from pine wood was significantly lower than that from other materials, the performance data indicate that the TSM provides a repeatable and responsive test for determining the efficacy of liquid sporicides on both porous and nonporous materials.

scholarly journals Reproductive biology of the Ilex species (Aquifoliaceae) in Hong Kong, China

2005 ◽  
Vol 83 (12) ◽  
pp. 1645-1654 ◽  
Author(s):  
Anita C.W. Tsang ◽  
Richard T. Corlett
Keyword(s):  
Hong Kong ◽  
Sugar Content ◽  
Large Population ◽  
Apis Cerana ◽  
Reproductive Investment ◽  
Female Mortality ◽  
Fruit Removal ◽  
Fruit Maturity ◽  
The Mean ◽  
Immature Heart

Fourteen wild species of shrubs and trees in the dioecious genus Ilex occur in Hong Kong (22°N, 114°E). All species flowered and formed fruits once each year. Sex ratios at flowering were male biased in all but one large population studied and, in most cases, this bias could not be explained by earlier flowering in males or higher female mortality. Apis cerana accounted for >87% of flower visits in all species and there was a significant positive relationship across species between the number of visits per flower per hour and the estimated mean number of flowers on a plant. The large green fruits of Ilex chapaensis Merr. were consumed only by masked palm civets, Paguma larvata, while the red or black fruits of other species were consumed by birds. The rate of fruit removal across species was positively related to sugar content and negatively related to phenolic and saponin contents. The mean number of pyrenes per fruit was 4.0–6.2 and the mean percentage of pyrenes containing seeds was 49%–90%. Most embryos were immature (heart shaped) at fruit maturity, but <50% of embryos developed further in some species. Floral investment was 0.93–5.84 times higher in male plants, but total reproductive investment was 0.62–8.3 higher in females.

scholarly journals A Special Report on 2019 International Planning Competition and a Comprehensive Analysis of Its Results

2020 ◽  
Vol 10 ◽  
Author(s):  
Jiayun Chen ◽  
Jianrong Dai ◽  
Ahmad Nobah ◽  
Sen Bai ◽  
Nan Bi ◽  
...  
Keyword(s):  
Work Experience ◽  
Medical Physics ◽  
Large Population ◽  
Locally Advanced ◽  
Planning System ◽  
Treatment Planning System ◽  
Plan Quality ◽  
Wide Range ◽  
The Mean ◽  
International Planning

PurposeThe aim of this work is to introduce the 2019 International Planning Competition and to analyze its results.Methods and materialsA locally advanced non-small cell lung cancer (LA-NSCLC) case using the simultaneous integrated boost approach was selected. The plan quality was evaluated by using a ranking system in accordance with practice guidelines. Planners used their clinical Treatment Planning System (TPS) to generate the best possible plan along with a survey, designed to obtain medical physics aspects information. We investigated the quality of the large population of plans designed by worldwide planners using different planning and delivery systems. The correlations of plan quality with relevant planner characteristics (work experience, department scale, and competition experience) and with technological parameters (TPS and modality) were examined.ResultsThe number of the qualified plans was 287 with a wide range of scores (38.61–97.99). The scores showed statistically significant differences by the following factors: 1) department scale: the mean score (89.76 ± 8.36) for planners from the departments treating &gt;2,000 patients annually was the highest of all; 2) competition experience: the mean score for the 107 planners with previous competition experience was 88.92 ± 9.59, statistically significantly from first-time participants (p = .001); 3) techniques: the mean scores for planners using VMAT (89.18 ± 6.43) and TOMO (90.62 ± 7.60) were higher than those using IMRT (82.28 ± 12.47), with statistical differences (p &lt;.001). The plan scores were negligibly correlated with the planner’s years of work experience or the type of TPS used. Regression analysis demonstrated that plan score was associated with dosimetric objectives that were difficult to achieve, which is generally consistent with a clinical practice evaluation. However, 51.2% of the planners abandoned the difficult component of total lung receiving a dose of 5 Gy in their plan design to achieve the optimal plan.ConclusionThe 2019 international planning competition was carried out successfully, and its results were analyzed. Plan quality was not correlated with work experiences or the TPS used, but it was correlated with department scale, modality, and competition experience. These findings differed from those reported in previous studies.

scholarly journals 1180 2D and 3D assessment of the left ventricle volume and ejection fraction in a general population

2020 ◽  
Vol 21 (Supplement_1) ◽  
Author(s):  
F Ericsson ◽  
B Tayal ◽  
K Hay Kragholm ◽  
T Zaremba ◽  
N Holmark Andersen ◽  
...  
Keyword(s):  
General Population ◽  
Left Ventricle ◽  
Ejection Fraction ◽  
Large Population ◽  
Systolic Volume ◽  
End Diastolic Volume ◽  
Significant Difference ◽  
End Systolic Volume ◽  
The Mean ◽  
2D And 3D

Abstract Introduction In standard practice, LV volumes and EF are estimated by 2D technique. 3D echocardiographic assessment seems more reliable; however, this method has not yet been validated in the general population. Purpose To validate 3D echocardiography in a large population sample and investigate differences between 2D and 3D LVEF and volumes Methods In The Copenhagen City Heart Study, 4466 echocardiograms were available for analysis. The echocardiograms were obtained during four consecutive heartbeats in both 2D and 3D with GE Vivid E9. Offline analysis was performed on EchoPac v. 201. LVEF was calculated by the modified Simpsons Biplane Auto EF for 2D and by the 4LVQ method for 3D. Results The study included 2090 echocardiograms. The mean 2D LVEF was 57.3 ± 6.1% (IQR 54 - 61%) and 51.7 ± 7.9% (IQR 47 - 57%) by 3D. The mean end-diastolic volume (EDV) and end-systolic volume (ESV) by 2D and 3D techniques were: EDV 2D 106.1 ± 29.6 ml vs EDV 3D 128.2 ± 32.3 ml , ESV 2D 45.7 ± 15.6 ml vs. ESV 3D 45.7 ± 20.7 , p &lt; 0.05 among all variables. The average difference of means between 2D and 3D LVEF was 5.6 ± 11.2%, -22.1 ± 56.8 ml for EDV, and -16.9 ± 32.9 ml for ESV. The correlation coefficient for LVEF was 0.42, EDV 0.76 and for ESV 0.70. Conclusion In our study, we found a significant difference in both LVEF and ventricular volumes when comparing 2D echocardiograms with 3D. 3DE had, in general, lower LVEF, higher EDV and ESV compared to 2D. Table 1: Summary of results Table 1 - Summary of results n = 2090 Variable Min Max Mean IQR (25-75) p-value LVEF, 2D (%) 18 76 57.3 ± 6.1 54-61 &lt; 0.05 LVEF, 3d (%) 13 77 51.7 ± 7.9 47-57 &lt; 0.05 EDV, 2D (ml) 13 275 106.1 ± 29.6 85-123.8 &lt; 0.05 EDV, 3D (ml) 50 270 128.2 ± 32.3 106-148 &lt; 0.05 ESV, 2D (ml) 15 150 45.7 ± 15.6 35-54 &lt; 0.05 ESV, 3D (ml) 13 185 45.7 ± 20.7 48-74 &lt; 0.05 LVEF: left ventricle ejection fraction, EDV: end-diastolic volume, ESV: end systolic volume, IQR: Inter-quartile range Abstract 1180 Figure 1: Correlation and BA-plot

Growth, Mortality and Movements of a Sanctuary Population of Maskinonge (Esox masquinongy Mitchill)

1956 ◽  
Vol 13 (5) ◽  
pp. 599-612 ◽  
Author(s):  
E. J. Crossman
Keyword(s):  
Large Population ◽  
Age Groups ◽  
Population Estimate ◽  
First Year ◽  
Esox Masquinongy ◽  
The Third ◽  
Hatchery Fish ◽  
The Mean ◽  
Age Limits ◽  
Annual Mortality

A Schumacher population estimate based on 995 maskinonge taken by trap nets, between the months of May and October in the years 1951–1953, set the number of maskinonge in Nogies Creek at between 769 and 1,122 in July 1953. The mean standard length of these fish was 53.0 cm. The rate of growth (26.3 cm. S.L. in the first year) compared favourably with that for maskinonge in other waters. Fish of age-groups II, III and IV predominated. The small number of fish over four years of age was apparently due to a 70% annual mortality rate at least after the third year of life and perhaps before age III.Recaptures of tagged maskinonge demonstrated that there was little movement of maskinonge in summer, and what movement there was, was mainly upstream. In the fall there was far more movement of fish, and this was mainly in a downstream direction.The area supports a fairly large population of maskinonge but the high mortality after three years of age limits its value for raising maskinonge to legal size. The potential for rearing fish to three years of age is such that it may be very advantageous to move hatchery fish here for one or two years before liberation.

Brechung und Reflexion schneller Elektronen durch dünne Folien

1968 ◽  
Vol 23 (12) ◽  
pp. 1988-1994
Author(s):  
H. Zeidl ◽  
H. Baier
Keyword(s):  
Energy Loss ◽  
Secondary Electron Emission ◽  
Experimental Methods ◽  
Relativistic Electrons ◽  
Angle Of Incidence ◽  
Step Method ◽  
Computational Program ◽  
Thin Foils ◽  
The Monte Carlo Method ◽  
The Mean

The Monte Carlo method is applied to investigate the penetration of fast electron through thin foils of matter. The “step by step method” is used. Energy loss and secondary electron emission are taken into account. As an example for the possible application of the computational program we calculated “refraction” and “reflection” of relativistic electrons on thin Al-foils. Scattering and reflection depends significantly on the energy loss of the electrons in the foil. The “mean scattering angle” of the electron beam (with respect to the foil normal) has been shown to be smaller than the angle of incidence (with respect to the foil normal). Possible experimental methods to test the predictions on mean scattering and reflection angles (as defined in this paper) are discussed.

A bivariate birth-death process which approximates to the spread of a disease involving a vector

1972 ◽  
Vol 9 (01) ◽  
pp. 65-75 ◽  
Author(s):  
D. A. Griffiths
Keyword(s):  
Simple Model ◽  
Probability Distribution ◽  
General Class ◽  
Large Population ◽  
Vector Model ◽  
Death Process ◽  
The Mean ◽  
Probability Of Extinction ◽  
Over Time ◽  
Birth Death

A simple model for a bivariate birth-death process is proposed. This model approximates to the host-vector epidemic situation. An investigation of the transient process is made and the mean behaviour over time is explicitly found. The probability of extinction and the behaviour of the process conditional upon extinction are examined and the probability distribution of the cumulative population size to extinction is found. Appropriate circumstances are suggested under which the model might possibly be applied to malaria. The host-vector model is classified within a general class of models which represent large population approximations to epidemics involving two types of infectives.

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