R-factors affecting host generation time: Their influence on sensitivity testing

Animals are associated with a microbiome that can affect their reproductive success. It is, therefore, important to understand how a host and its microbiome coevolve. According to the hologenome concept, hosts and their microbiome form an integrated evolutionary entity, a holobiont, on which selection can potentially act directly. However, this view is controversial, and there is an active debate on whether the association between hosts and their microbiomes is strong enough to allow for selection at the holobiont level. Much of this debate is based on verbal arguments, but a quantitative framework is needed to investigate the conditions under which selection can act at the holobiont level. Here, we use multilevel selection theory to develop such a framework. We found that selection at the holobiont level can in principle favor a trait that is costly to the microbes but that provides a benefit to the host. However, such scenarios require rather stringent conditions. The degree to which microbiome composition is heritable decays with time, and selection can only act at the holobiont level when this decay is slow enough, which occurs when vertical transmission is stronger than horizontal transmission. Moreover, the host generation time has to be short enough compared with the timescale of the evolutionary dynamics at the microbe level. Our framework thus allows us to quantitatively predict for what kind of systems selection could act at the holobiont level.

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Variation in noninvasive ventilation use in amyotrophic lateral sclerosis

Neurology ◽

10.1212/wnl.0000000000007776 ◽

2019 ◽

Vol 93 (3) ◽

pp. e306-e316 ◽

Cited By ~ 3

Author(s):

Nimish J. Thakore ◽

Brittany R. Lapin ◽

Erik P. Pioro ◽

Loutfi S. Aboussouan

Keyword(s):

Clinical Trials ◽

Amyotrophic Lateral Sclerosis ◽

Noninvasive Ventilation ◽

Rating Scale ◽

Factors Affecting ◽

Cox Proportional Hazard ◽

Bulbar Onset ◽

Cox Proportional Hazard Models ◽

R Factors ◽

Lateral Sclerosis

ObjectiveWe sought to examine prevalence and predictors of noninvasive ventilation (NIV) in a composite cohort of patients with amyotrophic lateral sclerosis (ALS) followed in a clinical trials setting (Pooled Resource Open-Access ALS Clinical Trials database).MethodsNIV initiation and status were ascertained from response to question 12 of the revised ALS Functional Rating Scale (ALSFRS-R). Factors affecting NIV use in patients with forced vital capacity (FVC) ≤50% of predicted were examined. Predictors of NIV were evaluated by Cox proportional hazard models and generalized linear mixed models.ResultsAmong 1,784 patients with 8,417 simultaneous ALSFRS-R and FVC% measures, NIV was used by 604 (33.9%). Of 918 encounters when FVC% ≤50%, NIV was reported in 482 (52.5%). Independent predictors of NIV initiation were lower FVC% (hazard ratio [HR] 1.27, 95% confidence interval [CI] 1.17–1.37 for 10% drop), dyspnea (HR 2.62, 95% CI 1.87–3.69), orthopnea (HR 4.09, 95% CI 3.02–5.55), lower bulbar and gross motor subscores of ALSFRS-R (HRs 1.09 [95% CI 1.03–1.14] and 1.13 [95% CI 1.07–1.20], respectively, per point), and male sex (HR 1.73, 95% CI 1.31–2.28). Adjusted for other variables, bulbar onset did not significantly influence time to NIV (HR 0.72, 95% CI 0.47–1.08). Considerable unexplained variability in NIV use was found.ConclusionNIV use was lower than expected in this ALS cohort that was likely to be optimally managed. Absence of respiratory symptoms and female sex may be barriers to NIV use. Prospective exploration of factors affecting adoption of NIV may help bridge this gap and improve care in ALS.

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The role of multilevel selection in host microbiome evolution

10.1101/663351 ◽

2019 ◽

Author(s):

Simon van Vliet ◽

Michael Doebeli

Keyword(s):

Generation Time ◽

Evolutionary Dynamics ◽

Horizontal Transmission ◽

Multilevel Selection ◽

Microbiome Composition ◽

Active Debate ◽

Multilevel Selection Theory ◽

Verbal Arguments ◽

Host Generation

Animals are associated with a microbiome that can affect their reproductive success. It is therefore important to understand how a host and its microbiome coevolve. According to the hologenome concept, hosts and their microbiome form an integrated evolutionary entity, a holobiont, on which selection can potentially act directly. However, this view is controversial and there is an active debate on whether the association between hosts and their microbiomes is strong enough to allow for selection at the holobiont level. Much of this debate is based on verbal arguments, but a quantitative framework is needed to investigate the conditions under which selection can act at the holobiont level. Here we use multilevel selection theory to develop such a framework. We found that selection at the holobiont level can in principle favor a trait that is costly to the microbes but that provides a benefit to the host. However, such scenarios require rather stringent conditions. The degree to which microbiome composition is heritable decays with time, and selection can only act at the holobiont level when this decay is slow enough, which occurs when vertical transmission is stronger than horizontal transmission. Moreover, the host generation time has to be short enough compared to the timescale of the evolutionary dynamics at the microbe level. Our framework thus allows us to quantitatively predict for what kind of systems selection could act at the holobiont level.

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Media factors affecting Augmentin disc sensitivity testing results

Journal of Antimicrobial Chemotherapy ◽

10.1093/jac/10.1.75 ◽

1982 ◽

Vol 10 (1) ◽

pp. 75-77 ◽

Cited By ~ 3

Author(s):

E. M. BROWN ◽

C. D. RIBEIRO

Keyword(s):

Sensitivity Testing ◽

Factors Affecting

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Resource Turnover Time and Consumer Generation Time as Factors Affecting the Stability of Coexistence: An Experiment with Drosophila

Journal of Animal Ecology ◽

10.2307/5162 ◽

1990 ◽

Vol 59 (1) ◽

pp. 121 ◽

Cited By ~ 3

Author(s):

Paul Mitchell ◽

Wallace Arthur

Keyword(s):

Generation Time ◽

Turnover Time ◽

Factors Affecting ◽

The Stability

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Some Factors affecting the Generation Time of Erysiphe graminis f. sp. hordei on Leaves of Three Barley Varieties

Journal of Phytopathology ◽

10.1111/j.1439-0434.1976.tb01708.x ◽

1976 ◽

Vol 86 (4) ◽

pp. 345-352 ◽

Cited By ~ 2

Author(s):

G. E. Russell ◽

S. Muszanskyj

Keyword(s):

Generation Time ◽

Erysiphe Graminis ◽

Factors Affecting

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Progress In The Practical Application Of Automated Image Analysis To Tem Negatives

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100078614 ◽

1977 ◽

Vol 35 ◽

pp. 214-217

Author(s):

F. A. Heckman ◽

E. Redman ◽

J.E. Connolly

Keyword(s):

Image Analysis ◽

Image Quality ◽

Exposure Time ◽

Image Contrast ◽

Automated Image Analysis ◽

Practical Application ◽

Factors Affecting ◽

High Image Quality ◽

Qualitative Evidence ◽

Comprehensive Study

In our initial publication on this subject1) we reported results demonstrating that contrast is the most important factor in producing the high image quality required for reliable image analysis. We also listed the factors which enhance contrast in order of the experimentally determined magnitude of their effect. The two most powerful factors affecting image contrast attainable with sheet film are beam intensity and KV. At that time we had only qualitative evidence for the ranking of enhancing factors. Later we carried out the densitometric measurements which led to the results outlined below.Meaningful evaluations of the cause-effect relationships among the considerable number of variables in preparing EM negatives depend on doing things in a systematic way, varying only one parameter at a time. Unless otherwise noted, we adhered to the following procedure evolved during our comprehensive study:Philips EM-300; 30μ objective aperature; magnification 7000- 12000X, exposure time 1 second, anti-contamination device operating.

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Factors affecting microstructural scale in liquid crystalline polymers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100174230 ◽

1990 ◽

Vol 48 (4) ◽

pp. 220-221

Author(s):

Christine M. Dannels ◽

Christopher Viney

Keyword(s):

Liquid Crystalline ◽

Liquid Crystalline Polymers ◽

Factors Affecting ◽

Crystalline Polymers ◽

Thermal Expansion Coefficients ◽

Low Thermal Expansion ◽

Lower Viscosity ◽

Fine Microstructure ◽

Planar Orientation ◽

Strength And Stiffness

Processing polymers from the liquid crystalline state offers several advantages compared to processing from conventional fluids. These include: better axial strength and stiffness in fibers, better planar orientation in films, lower viscosity during processing, low solidification shrinkage of injection moldings (thermotropic processing), and low thermal expansion coefficients. However, the compressive strength of the solid is disappointing. Previous efforts to improve this property have focussed on synthesizing stiffer molecules. The effect of microstructural scale has been overlooked, even though its relevance to the mechanical and physical properties of more traditional materials is well established. By analogy with the behavior of metals and ceramics, one would expect a fine microstructure (i..e. a high density of orientational defects) to be desirable.Also, because much microstructural detail in liquid crystalline polymers occurs on a scale close to the wavelength of light, light is scattered on passing through these materials.

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