scholarly journals A direct estimate of the size of the illusory spots in the Hermann Grid Illusion

2010 ◽  
Vol 3 (9) ◽  
pp. 754-754
Author(s):  
T. Macuda ◽  
K. Johnston ◽  
B. Timney
Keyword(s):  
Direct Estimate ◽  
Hermann Grid Illusion

scholarly journals Direct Estimate of the Mutation Rate and the Distribution of Fitness Effects in the Yeast Saccharomyces cerevisiae

Genetics ◽  
2001 ◽  
Vol 159 (2) ◽  
pp. 441-452
Author(s):  
Dominika M Wloch ◽  
Krzysztof Szafraniec ◽  
Rhona H Borts ◽  
Ryszard Korona
Keyword(s):  
Spontaneous Mutation ◽  
Fruit Fly ◽  
Diploid Cell ◽  
Induced Mutations ◽  
Direct Estimate ◽  
Yeast Saccharomyces Cerevisiae ◽  
Related Trait ◽  
First Time ◽  
Defective Mismatch Repair

Abstract Estimates of the rate and frequency distribution of deleterious effects were obtained for the first time by direct scoring and characterization of individual mutations. This was achieved by applying tetrad analysis to a large number of yeast clones. The genomic rate of spontaneous mutation deleterious to a basic fitness-related trait, that of growth rate, was U = 1.1 × 10−3 per diploid cell division. Extrapolated to the fruit fly and humans, the per generation rate would be 0.074 and 0.92, respectively. This is likely to be an underestimate because single mutations with selection coefficients s < 0.01 could not be detected. The distribution of s ≥ 0.01 was studied both for spontaneous and induced mutations. The latter were induced by ethyl methanesulfonate (EMS) or resulted from defective mismatch repair. Lethal changes accounted for ~30–40% of the scored mutations. The mean s of nonlethal mutations was fairly high, but most frequently its value was between 0.01 and 0.05. Although the rate and distribution of very small effects could not be determined, the joint share of such mutations in decreasing average fitness was probably no larger than ~1%.

scholarly journals Direct estimate of the internal π-donation to the carbene centre within N-heterocyclic carbenes and related molecules

2015 ◽  
Vol 11 ◽  
pp. 2727-2736 ◽  
Author(s):  
Diego M Andrada ◽  
Nicole Holzmann ◽  
Thomas Hamadi ◽  
Gernot Frenking
Keyword(s):  
Density Functional Theory ◽  
Density Functional ◽  
Decomposition Analysis ◽  
Heterocyclic Carbenes ◽  
Energy Decomposition Analysis ◽  
Energy Decomposition ◽  
Direct Estimate ◽  
Functional Theory ◽  
Bonding Analysis

Fifteen cyclic and acylic carbenes have been calculated with density functional theory at the BP86/def2-TZVPP level. The strength of the internal X→p(π) π-donation of heteroatoms and carbon which are bonded to the C(II) atom is estimated with the help of NBO calculations and with an energy decomposition analysis. The investigated molecules include N-heterocyclic carbenes (NHCs), the cyclic alkyl(amino)carbene (cAAC), mesoionic carbenes and ylide-stabilized carbenes. The bonding analysis suggests that the carbene centre in cAAC and in diamidocarbene have the weakest X→p(π) π-donation while mesoionic carbenes possess the strongest π-donation.

scholarly journals A Direct Estimate of Volume, Heat, and Freshwater Exchange Across the Greenland‐Iceland‐Faroe‐Scotland Ridge

2018 ◽  
Vol 123 (10) ◽  
pp. 7139-7153 ◽  
Author(s):  
T. Rossby ◽  
C. Flagg ◽  
Leon Chafik ◽  
Ben Harden ◽  
Henrik Søiland
Keyword(s):  
Direct Estimate ◽  
Volume Heat

scholarly journals Direct estimate of the spontaneous mutation rate uncovers the effects of drift and recombination in theChlamydomonas reinhardtiiplastid genome

2015 ◽  
Author(s):  
Rob W Ness ◽  
Susanne A Kraemer ◽  
Nick Colegrave ◽  
Peter D Keightley
Keyword(s):  
Mutation Rate ◽  
Genetic Drift ◽  
Plastid Genome ◽  
De Novo ◽  
Spontaneous Mutation ◽  
Genome Structure ◽  
Nuclear Genome ◽  
De Novo Mutation ◽  
Direct Estimate ◽  
Plastid Genomes

Plastids perform crucial cellular functions, including photosynthesis, across a wide variety of eukaryotes. Since endosymbiosis, plastids have maintained independent genomes that now display a wide diversity of gene content, genome structure, gene regulation mechanisms, and transmission modes. The evolution of plastid genomes depends on an input ofde novomutation, but our knowledge of mutation in the plastid is limited to indirect inference from patterns of DNA divergence between species. Here, we use a mutation accumulation experiment, where selection acting on mutations is rendered ineffective, combined with whole-plastid genome sequencing to directly characterize de novo mutation inChlamydomonas reinhardtii. We show that the mutation rates of the plastid and nuclear genomes are similar, but that the base spectra of mutations differ significantly. We integrate our measure of the mutation rate with a population genomic dataset of 20 individuals, and show that the plastid genome is subject to substantially stronger genetic drift than the nuclear genome. We also show that high levels of linkage disequilibrium in the plastid genome are not due to restricted recombination, but are instead a consequence of increased genetic drift. One likely explanation for increased drift in the plastid genome is that there are stronger effects of genetic hitchhiking. The presence of recombination in the plastid is consistent with laboratory studies inC. reinhardtiiand demonstrates that although the plastid genome is thought to be uniparentally inherited, it recombines in nature at a rate similar to the nuclear genome.

New estimates for the heat flux across the Polar Front: spatial and temporal variability in recent years

2013 ◽  
Vol 25 (3) ◽  
pp. 433-444 ◽  
Author(s):  
João Marcos Azevedo Correia De Souza ◽  
Afonso De Moraes Paiva ◽  
Karina Von Schuckmann
Keyword(s):  
Heat Flux ◽  
Heat Balance ◽  
Polar Front ◽  
Spatial And Temporal Variability ◽  
Large Contribution ◽  
Direct Estimate ◽  
Atlantic Sector ◽  
Eddy Heat Flux ◽  
Temporal And Spatial Variability ◽  
Eddy Fluxes

AbstractTwo different methodologies are applied in order to quantify the eddy contribution to the heat flux across the Polar Front, between January 2006 and December 2009. First, the eddy fluxes are indirectly estimated through a heat balance based on geostrophic fluxes obtained from the Argo climatological temperature and salinity. Second, a parametric model based on sea level anomaly data from a merged satellite product is used to obtain a direct estimate of the eddy heat flux and its temporal and spatial variability. The results obtained through the heat balance (-80.5 ± 16.45 x 1013 W) and the parameterization (-56.2 ± 4.18 x 1013 W) are within the range established by previous studies. The eddy heat flux is observed to be concentrated in a few narrow regions, with a particularly large contribution from the Atlantic sector. A trend of intensification of the southward heat flux is observed in the study period (-0.44 x 1013 W year-1), compatible with recent modelling and observational studies.

scholarly journals Abundant, hot water toward young stellar objects

1997 ◽  
Vol 178 ◽  
pp. 397-400
Author(s):  
F.P. Helmich ◽  
E.F. Van Dishoeck ◽  
J.H. Black ◽  
Th. De Graauw
Keyword(s):  
Hot Water ◽  
Resolving Power ◽  
Young Stellar Objects ◽  
Small Scale ◽  
Interstellar Space ◽  
Infrared Space Observatory ◽  
Direct Estimate ◽  
Infrared Source ◽  
Stellar Objects ◽  
Star Forming

The large amount of water vapour in the Earth's atmosphere makes it extremely difficult to observe water in interstellar space, except under unusual conditions (e.g., masers). The Short Wavelength Spectrometer (SWS; de Graauw et al. 1996) on board the Infrared Space Observatory (ISO) provides an unique opportunity to study the ro-vibrational fundamental bands of water in absorption against bright infrared continuum sources. Such absorption line data have several advantages over emission observations. For example, only a pencil beam to the infrared source is probed, which minimizes the complications due to the small-scale physical and chemical heterogeneity of star-forming regions. In addition, lines from all rotational levels are present within a vibrational band, so that the complete spectrum yields a direct estimate of the level populations and excitation temperature along the line of sight. Other molecules, such as CO, HCN and C2H2, can be observed with the same technique, leading to accurate relative abundances. The main limitation of the ISO-SWS grating is its low spectral resolving power, λ/Δ λ ≈ 1350 at 6 μm, since the lines are intrinsically much narrower. This limits the sensitivity, so that only high column densities can be detected, and complicates the interpretation because detectable lines are often saturated. The low spectral resolution also blends the lines, making it difficult to determine the equivalent widths unambiguously. The ISO-SWS is therefore particularly sensitive to molecules in warm gas with relatively large line widths (Δ V > 3 km s−1).

Laser-Induced Fluorescence in Mononuclear Cells: Direct Estimate of the NADH Bound/Free Ratio

2010 ◽  
pp. 199-217
Author(s):  
A. Silva-Pérez ◽  
J. R. Godínez-Fernández ◽  
M. Fernández-Guasti ◽  
E. Haro-Poniatowski ◽  
C. Campos-Muñiz ◽  
...  
Keyword(s):  
Mononuclear Cells ◽  
Laser Induced Fluorescence ◽  
Direct Estimate

The relative efficiency of direct and maximum likelihood estimates of mean waiting time in the simple queue, M/M/1

1972 ◽  
Vol 9 (2) ◽  
pp. 396-403 ◽  
Author(s):  
John H. Jenkins
Keyword(s):  
Maximum Likelihood ◽  
Waiting Time ◽  
Continuous Time ◽  
Relative Efficiency ◽  
Asymptotic Variance ◽  
Complete Information ◽  
Maximum Likelihood Estimates ◽  
Time Study ◽  
Direct Estimate ◽  
Mean Waiting Time

A problem of estimating waiting time in the statistical analysis of queues is investigated. The continuous time study of the M/M/1 queue made by Bailey is adapted to obtain the asymptotic variance of a direct estimate of waiting time as obtained under conditions of incomplete information. This is then compared with the asymptotic variance of the maximum likelihood estimate as obtained under conditions of complete information and based on the results of Clarke.

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