scholarly journals Evolution of bacterial transformation: is sex with dead cells ever better than no sex at all?

Genetics ◽  
1988 ◽  
Vol 119 (1) ◽  
pp. 213-221
Author(s):  
R J Redfield
Keyword(s):  
Deleterious Mutation ◽  
Fitness Function ◽  
Bacterial Transformation ◽  
Wide Range ◽  
Mean Fitness ◽  
The Mean ◽  
Transforming Cell ◽  
Asexual Populations ◽  
The Relationship ◽  
Better Than

Abstract Computer simulations of bacterial transformation are used to show that, under a wide range of biologically reasonable assumptions, transforming populations undergoing deleterious mutation and selection have a higher mean fitness at equilibrium than asexual populations. The source of transforming DNA, the amount of DNA taken up by each transforming cell, and the relationship between number of mutations and cell viability (the fitness function) are important factors. When the DNA source is living cells, transformation resembles meiotic sex. When the DNA source is cells killed by selection against mutations, transformation increases the average number of mutations per genome but can nevertheless increase the mean fitness of the population at equilibrium. In a model of regulated transformation, in which the most fit cells of a transforming population do not transform, transforming populations are always fitter at equilibrium than asexual populations. These results show that transformation can reduce mutation load.

scholarly journals The mutation load under tetrasomic inheritance and its consequences for the evolution of the selfing rate in autotetraploid species

1999 ◽  
Vol 74 (1) ◽  
pp. 31-42 ◽  
Author(s):  
J. RONFORT
Keyword(s):  
Inbreeding Depression ◽  
Deleterious Mutation ◽  
Stable State ◽  
Approximate Solutions ◽  
Balance Model ◽  
Deleterious Mutations ◽  
Selfing Rate ◽  
Mutation Load ◽  
Mean Fitness ◽  
The Mean

Single-locus equilibrium frequencies of a partially recessive deleterious mutation under the mutation–selection balance model are derived for partially selfing autotetraploid populations. Assuming multiplicative fitness interactions among loci, approximate solutions for the mean fitness and inbreeding depression values are also derived for the multiple locus case and compared with expectations for the diploid model. As in diploids, purging of deleterious mutations through consanguineous matings occurs in autotetraploid populations, i.e. the equilibrium mutation load is a decreasing function of the selfing rate. However, the variation of inbreeding depression with the selfing rate depends strongly on the dominance coefficients associated with the three heterozygous genotypes. Inbreeding depression can either increase or decrease with the selfing rate, and does not always vary monotonically. Expected issues for the evolution of the selfing rate consequently differ depending on the dominance coefficients. In some cases, expectations for the evolution of the selfing rate resemble expectations in diploids; but particular sets of dominance coefficients can be found that lead to either complete selfing or intermediate selfing rates as unique evolutionary stable state.

scholarly journals Study on Tribological Properties and Mechanisms of Different Morphology WS2 as Lubricant Additives

Materials ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1522 ◽  
Author(s):  
Ningning Hu ◽  
Xiuheng Zhang ◽  
Xianghui Wang ◽  
Na Wu ◽  
Songquan Wang
Keyword(s):  
Wear Resistance ◽  
Optimum Condition ◽  
Lubricating Oil ◽  
Stribeck Curve ◽  
Extreme Pressure ◽  
Friction Process ◽  
Wide Range ◽  
The Coefficient Of Friction ◽  
The Relationship ◽  
Better Than

In the present work, the relationship curve of the coefficient of friction (COF) with varying loads of different morphology WS2 lubricating additives in the friction process at various sliding speeds was studied. On this basis, wear marks and elements on the wear surfaces after friction were analyzed, and then the anti-wear and mechanism effects of WS2 of different forms in the lubrication process were discussed. Meanwhile, the Stribeck curve was used to study the lubrication state of the lubricating oil in the friction process. It was revealed that the COF of lubricating oil containing lamellar WS2 decreased by 29.35% at optimum condition and the minimum COF was concentrated at around 100 N. The COF of lubricating oil containing spherical WS2 decreased by 30.24% and the minimum coefficient was concentrated at 120 N. The extreme pressure property of spherical WS2 was better than that of lamellar WS2, and the wear resistance of spherical WS2 was more stable when the load was over 80 N. The different morphology of WS2 additives can play anti-wear and anti-friction roles within a wide range of sliding speeds.

Cell structure and mechanical properties of microcellular PLA foams prepared via autoclave constrained foaming

2020 ◽  
pp. 026248932093032
Author(s):  
Jinwei Chen ◽  
Ling Yang ◽  
Dahua Chen ◽  
Qunshan Mai ◽  
Meigui Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cell Size ◽  
Cell Structure ◽  
Saturation Pressure ◽  
Tensile Modulus ◽  
Cell Structures ◽  
Wide Range ◽  
The Mean ◽  
Constrained Foaming ◽  
The Relationship

Microcellular polylactic acid (PLA) foams with various cell size and cell morphologies were prepared using supercritical carbon dioxide (sc-CO2) solid-state foaming to investigate the relationship between the cell structure and mechanical properties. Constrained foaming was used and a wide range of cell structures with a constant porosity of ∼75% by tuning saturation pressure (8–24 MPa) was developed. Experiments varying the saturation pressure while holding other variables’ constant show that the mean cell size and the mean cell wall thickness decreased, while the cell density and the open porosity increased with increase of pressure. Tensile modulus of PLA foams decreased with increasing the saturation pressure, but the specific tensile modulus of PLA foams was still 15–80% higher than that of solid PLA. Tensile strength and elongation at break first increased with increasing saturation pressure up to 16 MPa and then decreased with further increasing saturation pressure (20 MPa and 24 MPa) at which opened-cell structure produced. Compressive modulus, compressive strength, and compressive yield stress also followed the same variation trend. The results indicated that not only cell size plays an important role in properties of PLA foams but also cell morphology can influence these properties significantly.

Taxonomic status of Clematis acerifolia var. elobata, based on molecular evidence

Phytotaxa ◽  
2016 ◽  
Vol 268 (3) ◽  
pp. 209 ◽  
Author(s):  
SHUANG-XI YAN ◽  
HUI-JIE LIU ◽  
LE-LE LIN ◽  
SHUAI LIAO ◽  
JIN-YU LI ◽  
...  
Keyword(s):  
Taxonomic Status ◽  
Species Level ◽  
Distribution Area ◽  
Molecular Evidence ◽  
Discrimination Power ◽  
Nuclear Its ◽  
The Mean ◽  
Morphological Differences ◽  
The Relationship ◽  
Better Than

The morphologically based taxonomic status of Clematis acerifolia var. elobata has been controversial. This study used two nuclear (ITS and ETS) and six plastid (rps16, rpl16, accD, trnS-trnG, atpB-rbcL, and trnV-atpE) molecular markers, and a DNA barcoding analysis to address the taxonomic status of C. acerifolia var. elobata and the relationship among other Clematis species. Our results showed that the discrimination power of ITS, ETS, and atpB-rbcL was better than that of the other tested DNA regions. When all tested sequences combined, most of the sampled taxa were resolved. Though the two taxa are closely related, they have differentiated clearly and formed two clades respectively. The mean divergence of the two taxa was 0.78%, which was higher than closely related Clematis species such as C. heracleifolia and C. pinnata (0.50 %). Considering molecular divergence, morphological differences, and distribution area, we raised C. acerifolia var. elobata to species level.

Relationship between Rated Degree of Familiarity with Individual Sentences and the Extent of Recall of Connected Discourse

1966 ◽  
Vol 19 (3_suppl) ◽  
pp. 1195-1202 ◽  
Author(s):  
John A. Mills ◽  
Alan Nicolas-Fanourakis
Keyword(s):  
Rating Scale ◽  
Interference Theory ◽  
Connected Discourse ◽  
Wide Range ◽  
The Mean ◽  
The Individual ◽  
The Relationship

An assessment was made of the strength and direction of the relationship between rated degree of familiarity for connected discourse and the extent of recall of such material. The experimental material consisted of two short passages of prose (a narrative and an argument) and of a rating scale containing all the sentences from these passages inserted randomly among other individual sentences selected from a wide range of sources. 20 Ss provided both recall scores for the passages (which were presented whole) and familiarity ratings for the sentences in the rating scale. When recall scores for the individual sentences were correlated with the mean ratings, a positive and significant value was found. The bearing of this finding on (he expectations of interference theory is discussed.

Onset to reperfusion time as a determinant of outcomes across a wide range of ASPECTS in endovascular thrombectomy: pooled analysis of the SWIFT, SWIFT PRIME, and STAR studies

2019 ◽  
Vol 12 (3) ◽  
pp. 240-245 ◽  
Author(s):  
Joon-Tae Kim ◽  
Mayank Goyal ◽  
Elad I Levy ◽  
David Liebeskind ◽  
Reza Jahan ◽  
...  
Keyword(s):  
Pooled Analysis ◽  
Infarct Core ◽  
Endovascular Thrombectomy ◽  
Wide Range ◽  
Star Studies ◽  
The Mean ◽  
Treat All ◽  
Relationship Of ◽  
The Relationship ◽  
Core Infarct

BackgroundThe time–benefit relationship of endovascular thrombectomy (EVT) according to the size of the core infarct has been incompletely explored in prior studies. We investigated whether established infarct core size on baseline imaging modifies the relationship between onset-to-reperfusion time (OTR) and functional outcomes in patients with acute ischemic stroke treated with EVT.MethodsWe analyzed a database containing individual patient data pooled from three prospective Solitaire stent retriever studies. The inclusion criteria were treatment with a Solitaire device and achievement of substantial reperfusion (modified Thrombolysis in Cerebral Infarction 2b–3). Main analyses were performed in patients with baseline Alberta Stroke Program Early CT Scores (ASPECTSs) of 7–10.ResultsAmong the 305 patients (mean age 67±13 years, 58% women), the proportions of patients in different categories of pretreatment infarct extent were: small (ASPECTS 9–10) 52.0%, moderate (ASPECTS 7–8) 37.1%, and large (ASPECTS 0–6) 7.6%. The mean OTR was 297±95 min. At 3 months, 60.1% of the patients achieved a good outcome. For OTRs of 2–8 hours, the rates of good outcomes at all time points were higher with higher baseline ASPECTS but declined with similar steepness. Both baseline ASPECTS (OR 1.23 (95% CI 1.04 to 1.45)) and OTR (every 30 min delay, OR 0.80 (95% CI 0.73 to 0.88)) were independently associated with a good 3-month outcome. No interaction between OTR and baseline ASPECTS was observed.ConclusionsAlthough patients with higher baseline ASPECTS are more likely to have good clinical outcomes at all OTR intervals after 2 hours, this benefit consistently declines with time, even in patients with a small infarct core, reinforcing the need to treat all patients as quickly as possible.

The appraisal of fineness in greasy wool sale lots

1975 ◽  
Vol 85 (1) ◽  
pp. 45-52 ◽  
Author(s):  
K. J. Whiteley ◽  
D. Charlton
Keyword(s):  
Confidence Interval ◽  
Fibre Diameter ◽  
Mean Value ◽  
Wide Range ◽  
The Mean ◽  
The Relationship

SUMMARYRelationships among quality number, crimp frequency and. fibre diameter of sale lots are reported for a wide range of Australian wools, the quality number appraisals being those of the selling broker and the successful bidder at auction.Results show that sale lots classified as having the same quality number exhibit a 95% confidence interval of ± 2·5 μm about the mean value. This variation is attributed first to the dependence of quality number on staple crimp frequency and secondly to the strength of the relationship between crimp frequency and fibre diameter.

scholarly journals Usefulness of a real-time PCR platform for G+C content and DNA–DNA hybridization estimations in vibrios

2011 ◽  
Vol 61 (10) ◽  
pp. 2379-2383 ◽  
Author(s):  
Ana Paula B. Moreira ◽  
Nei Pereira ◽  
Fabiano L. Thompson
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Dna Hybridization ◽  
Sister Species ◽  
Wide Range ◽  
Significant Difference ◽  
The Mean ◽  
Vibrio Campbellii ◽  
The Relationship ◽  
Linear Regression Curve

The aim of this study was to evaluate the utility of a real-time PCR platform to estimate the DNA G+C content (mol%) and DNA–DNA hybridization (DDH) values in the genus Vibrio. In total, nine vibrio strains were used to determine the relationship between genomic DNA G+C content and T m (°C). The T m and HPLC datasets fit a linear regression curve with a significant correlation coefficient, corroborating that this methodology has a high correlation with the standard methodology based on HPLC (R2 = 0.94). Analysis of 31 pairs of vibrios provided a wide range of ΔT m values, varying between 0.72 and 12.5 °C. Pairs corresponding to strains of the same species or strains from sister species showed the lowest ΔT m values. For instance, the ΔT m of the sister species Vibrio harveyi LMG 4044T and Vibrio campbellii LMG 11216T was 5.2 °C, whereas the ΔT m of Vibrio coralliilyticus LMG 20984T and Vibrio neptunius LMG 20536T was 8.75 °C. The mean ΔT m values corresponding to pairs of strains with DDH values lower than 60 % or higher than 80 % were, respectively, 8.29 and 2.21 °C (significant difference, P<0.01). The high correlation between DDH values obtained in previous studies and the ΔT m values (R2 = 0.7344) indicates that the fluorimetric methodology is a reliable alternative for the estimation of both DNA G+C content and ΔT m in vibrios. We suggest that strains of the same Vibrio species will have less than 4 °C ΔT m. The use of a real-time PCR platform represents a valuable alternative for the development of the taxonomy of vibrios.

scholarly journals THE RATE OF OXYGEN UTILIZATION BY YEAST AS RELATED TO TEMPERATURE

1933 ◽  
Vol 16 (5) ◽  
pp. 815-840 ◽  
Author(s):  
T. J. B. Stier
Keyword(s):  
Oxygen Utilization ◽  
Critical Temperatures ◽  
Average Deviation ◽  
Yeast Saccharomyces Cerevisiae ◽  
Common System ◽  
Wide Range ◽  
Series Of Experiments ◽  
Single Determination ◽  
The Mean ◽  
The Relationship

Suspensions of the yeast Saccharomyces cerevisiae gave reproducible rates of O2 uptake over a period of 6 months. The relation of rate of consumption of O2 to temperature was tested over a wide range of temperatures, and the constant in the formulation of the relationship is found to be reproducible. The values of this constant (µ) have been obtained for five separate series of experiments by three methods of estimation. The variability of µ has the following magnitudes: the average deviation of a single determination expressed as per cent of the mean is ±2 per cent in the range 30–15°, and ±0.8 per cent in the range 15–3°C. This constancy of metabolic activity measured as a function of temperature can then be utilized for more precise investigations of processes controlling the velocity of oxidations of substrates, and of respiratory systems controlled by intracellular respiratory pigments. The data plotted according to the Arrhemus equation give average values of the constant µ as follows: for the range 35–30°, µ = 8,290; 30–15°, µ = 12,440 ±290; 15–3°, µ = 19,530 ±154. The critical temperatures are at 29.0° and 15.7°C. A close similarity exists between these temperature characteristics (µ) and values in the series usually obtained for respiratory activities in other organisms. This fact supports the view that a common system of processes controls the velocities of physiological activities in yeast and in other organisms.

scholarly journals Relationship between Perception of Maxillary Midline Diastema and Personality Profiles

2016 ◽  
Vol 7 (2) ◽  
pp. 59-63
Author(s):  
Abdullah A Al Nazeh
Keyword(s):  
Cross Sectional Study ◽  
Personality Profiles ◽  
Analog Scale ◽  
Cross Sectional ◽  
Psychological Profiles ◽  
Negative Perceptions ◽  
Vas Scores ◽  
The Mean ◽  
The Relationship ◽  
Better Than

ABSTRACT Aims The aim of this study was to investigate the relationship between personality profiles and perception of maxillary midline diastema (MMD) among laypeople. Materials and methods Hundred total of 200 laypeople (100 females and 100 males, mean age = 28.8 ± 5.5 years) were recruited in this cross-sectional study. They were asked to rate the attractiveness of two digital photographs of ideal smile with 1 and 2 mm MMD on a visual analog scale (VAS) from 0 to 10. Participants' personality and psychological profiles were assessed via neuroticism.extraversion.openness five-factor inventory. The statistically significant levels were set at p ≤ 0.05. Results The mean VAS scores were 5.7 (± 2.1) and 4.3 (± 2.0) for 1 and 2 mm MMD respectively. The participants rated the attractiveness of 1 mm diastema better than the attractiveness of 2 mm diastema (p < 0.001). Females showed no difference in rating diastema attractiveness in comparison with males (p > 0.05). Participants (from both genders) with higher neuroticism scores rated 1 and 2 mm diastemas as less attractive than those with lower neuroticism scores (p ≤ 0.001). Conclusion Psychological profiles (high neuroticism) might be associated with negative perceptions of attractiveness of MMD. How to cite this article Al Nazeh AA. Relationship between Perception of Maxillary Midline Diastema and Personality Profiles. World J Dent 2016;7(2):59-63.

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