scholarly journals Schrödinger’s ants: a continuous description of Kirman’s recruitment model

2020 ◽  
Vol 1 (3) ◽  
pp. 035002
Author(s):  
José Moran ◽  
Antoine Fosset ◽  
Michael Benzaquen ◽  
Jean-Philippe Bouchaud
2020 ◽  
Author(s):  
José Moran ◽  
Antoine Fosset ◽  
Michael Benzaquen ◽  
Jean-Philippe Bouchaud

1995 ◽  
Vol 79 (5) ◽  
pp. 1449-1460 ◽  
Author(s):  
S. D. Caruthers ◽  
T. R. Harris ◽  
K. A. Overholser ◽  
N. A. Pou ◽  
R. E. Parker

The effects of flow heterogeneity on the measurement of transcapillary escape of small molecules for perfused in situ sheep lungs were evaluated. Lungs were studied at five flows (1.5–5.0 l/min) ranging from zone 1 to zone 3 conditions. At each flow, multiple indicator-dilution curves were collected using 14C-labeled urea (U) or butanediol (B) as the diffusing tracer, and radiolabeled 15-microns microspheres were injected. The lungs were removed, dried, sectioned, weighed, and counted for microsphere radioactivity. Flow heterogeneity expressed as relative dispersion, decreased with increasing flow, from 0.838 +/- 0.179 (mean +/- SD, n = 8) to 0.447 +/- 0.119 (n = 6). We applied homogeneous flow models of capillary exchange to compute permeability-surface area product (PS) and a related parameter, D1/2S, for diffusing tracers. (D is effective diffusivity of capillary exchange.) PS and D1/2S increased to a maximum with increasing flow, but the ratio of D1/2SU to D1/2SB remained constant. A new model incorporating flow heterogeneity and recruitment (the variable recruitment model) was used. The variable recruitment model described the effects of flow on capillary recruitment, but incorporating heterogeneity into the computation did not alter D1/2S values from those computed assuming homogeneous flow.


2014 ◽  
Vol 72 (1) ◽  
pp. 111-116 ◽  
Author(s):  
M. Dickey-Collas ◽  
N. T. Hintzen ◽  
R. D. M. Nash ◽  
P-J. Schön ◽  
M. R. Payne

Abstract The accessibility of databases of global or regional stock assessment outputs is leading to an increase in meta-analysis of the dynamics of fish stocks. In most of these analyses, each of the time-series is generally assumed to be directly comparable. However, the approach to stock assessment employed, and the associated modelling assumptions, can have an important influence on the characteristics of each time-series. We explore this idea by investigating recruitment time-series with three different recruitment parameterizations: a stock–recruitment model, a random-walk time-series model, and non-parametric “free” estimation of recruitment. We show that the recruitment time-series is sensitive to model assumptions and this can impact reference points in management, the perception of variability in recruitment and thus undermine meta-analyses. The assumption of the direct comparability of recruitment time-series in databases is therefore not consistent across or within species and stocks. Caution is therefore required as perhaps the characteristics of the time-series of stock dynamics may be determined by the model used to generate them, rather than underlying ecological phenomena. This is especially true when information about cohort abundance is noisy or lacking.


2019 ◽  
Vol 29 (03) ◽  
pp. 1850049 ◽  
Author(s):  
Magdalena Zieleniewska ◽  
Anna Duszyk ◽  
Piotr Różański ◽  
Marcin Pietrzak ◽  
Marta Bogotko ◽  
...  

We propose a fully parametric approach to the assessment of sleep architecture, based upon the classical electroencephalographic criteria, applicable also to the recordings of patients with disorders of consciousness (DOC). Sleep spindles and slow waves are automatically detected from the matching pursuit decomposition of overnight EEG recordings. Their evolution can be presented in the form of EEG profiles, yielding a continuous description of sleep architecture, compatible with the classical criteria used in sleep staging. We propose assessment of these EEG profiles by five parameters, which can be combined by a linear classifier, assessing the quality of sleep architecture. Proposed methodology is evaluated on 59 overnight EEG recordings from 19 patients from a hospital for children with severe brain damage, in relation to their behavioral diagnosis according to the Coma Recovery Scale-Revised. Presented results indicate robustness of the proposed approach, which may serve as a valuable aid in diagnosis of DOC patients. Complete software environment for computing and presentation of EEG profiles is freely available from http://svarog.pl .


2020 ◽  
pp. 463-466
Author(s):  
D. Bonamy ◽  
B. Faucherand ◽  
M. Planelle ◽  
F. Daviaud ◽  
L. Laurent

2019 ◽  
Vol 17 (03) ◽  
pp. 393-423 ◽  
Author(s):  
J. A. Carrillo ◽  
M. G. Delgadino ◽  
F. S. Patacchini

We analyze free energy functionals for macroscopic models of multi-agent systems interacting via pairwise attractive forces and localized repulsion. The repulsion at the level of the continuous description is modeled by pressure-related terms in the functional making it energetically favorable to spread, while the attraction is modeled through nonlocal forces. We give conditions on general entropies and interaction potentials for which neither ground states nor local minimizers exist. We show that these results are sharp for homogeneous functionals with entropies leading to degenerate diffusions while they are not sharp for fast diffusions. The particular relevant case of linear diffusion is totally clarified giving a sharp condition on the interaction potential under which the corresponding free energy functional has ground states or not.


2021 ◽  
Vol 39 (15_suppl) ◽  
pp. e18574-e18574
Author(s):  
Rosa Nouvini ◽  
Patricia A. Parker ◽  
Charlotte Malling ◽  
Kendra Godwin ◽  
Rosario Costas-Muñiz

e18574 Background: Minorities continue to be underrepresented in clinical trials despite the National Institute of Health’s Revitalization Act, passed in 1993, mandating the representation of women and underrepresented minority groups in clinical trials. Studies have shown that although Blacks represent 15% and Hispanics 13% of the cancer population, their clinical trial enrollment rates in are disproportionately low at 4-6% and 3-6% respectively. We conducted a systematic review exploring interventions aimed at improving clinical trial enrollment for racial and ethnic minorities. Methods: A systematic search of PubMed, Cochrane CENTRAL, and Ovid PsycINFO was conducted for English-language studies of humans since 1993. Inclusion criteria included peer-reviewed, U.S.-based studies with interventions aimed to recruit underrepresented minority adult cancer patients into cancer clinical trials. We defined underrepresented minority groups as Black, Hispanic/Latino, Asian, American Indian/Alaska Native and Native Hawaiian/other Pacific Islander. Results: A total of 2471 titles and abstracts were identified and 2324 were excluded based on the eligibility criteria. A full text review was conducted of the remaining 147 articles, of which only 9 met criteria for our review. The interventions included patient navigation/coaching (n = 4), a clinical trial educational video (n = 2), institutional research infrastructure changes (n = 1), a relationship building and social marketing recruitment model (n = 1) and cultural competency training for providers (n = 1). Studies were conducted in a variety of practice settings including national cancer institutes and community practices. The quality of evidence was limited by the heterogeneity of study methods, patient representation and bias. Several studies had a homogeneous population of Black patients. Most studies (n = 7) were single arm trials that compared results to either historical controls or those cited in the existing literature; two studies were randomized controlled trials. A statistically significant improvement in accrual was shown in three of the patient navigation interventions, one of the clinical trial educational videos, the institutional research infrastructure change and the relationship building and social marketing recruitment model. The common threads to many of these successful interventions were support through the cancer care continuum, cultural congruency of research staff and culturally catered clinical trial educational materials. Conclusions: This systematic review illustrates several mechanisms by which to increase cancer clinical trial recruitment for cancer patients of underrepresented minority backgrounds in a variety of clinical settings. Randomized controlled trials with representation of multiple races/ethnicities are needed to further explore the benefits of these interventions.


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