The size-principle: a deterministic output emerges from a set of probabilistic connections

1985 ◽  
Vol 115 (1) ◽  
pp. 105-112 ◽  
Author(s):  
E. Henneman
Keyword(s):  
Large Population ◽  
Single Fibre ◽  
Cell Level ◽  
Size Principle ◽  
Transmission Failure ◽  
Fibre Size ◽  
Spike Triggered Averaging ◽  
A Cell ◽  
The Mean ◽  
Ia Fibres

Orderly, size-related recruitment of motoneurones (MNs) illustrates how hundreds of cells operate as a functional entity to produce a highly deterministic output. The coherent action of the pool depends largely on the distribution of input to its members through the connections of afferent fibres. Three types of spike-triggered averaging have been utilized to study these connections. Impulses in individual Ia afferents elicit excitatory postsynaptic potentials (‘single-fibre’ EPSPs) in about 80% of homonymous MNs. After spinal transection 100% may respond, suggesting that Ia fibres project anatomically to all homonymous MNs. Functionally absent Ia connections are due to transmission failure. The sum of all the EPSPs elicited in a large population of MNs was recorded electrotonically from ventral roots. The mean amplitudes of these ‘postsynaptic population potentials’ (PSPPs) were correlated with the conduction velocities (CVs) of the Ia or spindle group II fibres. The greater the distance between the spinal entry point of a Ia fibre and the ventral root, the smaller was the PSPP. Tape recording of multiple afferents and the responses of up to 24 MNs permitted study of as many as 264 possible connections in a single, acute experiment. Construction of wiring diagrams and connectivity matrices from the data showed that functional connectivity is influenced by afferent fibre size, the effect of branching on fibre size, MN size and probably transmission failure, but that on a cell-to-cell level, connectivity does not follow strict, deterministic rules. The results raise the question of how probabilistic connections between afferent fibres and MNs give rise to deterministic outputs from the whole pool.

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 Limit theorems for some branching measure-valued processes

2017 ◽  
Vol 49 (2) ◽  
pp. 549-580 ◽  
Author(s):  
Bertrand Cloez
Keyword(s):  
Continuous Time ◽  
Limit Theorems ◽  
Particle System ◽  
Large Population ◽  
Empirical Measure ◽  
Spatial Motion ◽  
Auxiliary Process ◽  
Discrete Population ◽  
A Cell ◽  
Fragmentation Equation

AbstractWe consider a particle system in continuous time, a discrete population, with spatial motion, and nonlocal branching. The offspring's positions and their number may depend on the mother's position. Our setting captures, for instance, the processes indexed by a Galton–Watson tree. Using a size-biased auxiliary process for the empirical measure, we determine the asymptotic behaviour of the particle system. We also obtain a large population approximation as a weak solution of a growth-fragmentation equation. Several examples illustrate our results. The main one describes the behaviour of a mitosis model; the population is size structured. In this example, the sizes of the cells grow linearly and if a cell dies then it divides into two descendants.

scholarly journals Effects of cell cycle variability on lineage and population measurements of mRNA abundance

2020 ◽  
Author(s):  
Ruben Perez-Carrasco ◽  
Casper Beentjes ◽  
Ramon Grima
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Negative Binomial ◽  
Eukaryotic Cell ◽  
Cycle Duration ◽  
Cell Cycle Duration ◽  
Monotonically Decreasing Function ◽  
Binomial Mixture ◽  
A Cell ◽  
The Mean

AbstractMany models of gene expression do not explicitly incorporate a cell cycle description. Here we derive a theory describing how mRNA fluctuations for constitutive and bursty gene expression are influenced by stochasticity in the duration of the cell cycle and the timing of DNA replication. Analytical expressions for the moments show that omitting cell cycle duration introduces an error in the predicted mean number of mRNAs that is a monotonically decreasing function of η, which is proportional to the ratio of the mean cell cycle duration and the mRNA lifetime. By contrast, the error in the variance of the mRNA distribution is highest for intermediate values of η consistent with genome-wide measurements in many organisms. Using eukaryotic cell data, we estimate the errors in the mean and variance to be at most 3% and 25%, respectively. Furthermore, we derive an accurate negative binomial mixture approximation to the mRNA distribution. This indicates that stochasticity in the cell cycle can introduce fluctuations in mRNA numbers that are similar to the effect of bursty transcription. Finally, we show that for real experimental data, disregarding cell cycle stochasticity can introduce errors in the inference of transcription rates larger than 10%.

A single cell approach to problems of cell lineage and commitment during embryogenesis of Drosophila melanogaster

Development ◽  
1987 ◽  
Vol 100 (1) ◽  
pp. 1-12 ◽  
Author(s):  
G.M. Technau
Keyword(s):  
Drosophila Melanogaster ◽  
Single Cell ◽  
Cell Lineage ◽  
Cellular Level ◽  
Central Importance ◽  
Cell Level ◽  
Combined Application ◽  
A Cell ◽  
Pole Cells ◽  
Drosophila Embryos

The mechanisms leading to the commitment of a cell to a particular fate or to restrictions in its developmental potencies represent a problem of central importance in developmental biology. Both at the genetic and at the molecular level, studies addressing this topic using the fruitfly Drosophila melanogaster have advanced substantially, whereas, at the cellular level, experimental techniques have been most successfully applied to organisms composed of relatively large and accessible cells. The combined application of the different approaches to one system should improve our understanding of the process of commitment as a whole. Recently, a method has been devised to study cell lineage in Drosophila embryos at the single cell level. This method has been used to analyse the lineages, as well as the state of commitment of single cell progenitors from various ectodermal, mesodermal and endodermal anlagen and of the pole cells. The results obtained from a clonal analysis of wild-type larval structures are discussed in this review.

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 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

scholarly journals A Cell-Level Mechanobiological Model of Drosophila Dorsal Closure

2013 ◽  
Vol 104 (2) ◽  
pp. 477a
Author(s):  
Qiming Wang ◽  
James J. Feng ◽  
Len Pismen
Keyword(s):  
Dorsal Closure ◽  
Cell Level ◽  
A Cell
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