ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your search history is empty.
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
Collection
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 41 (1995), S. 1152-1159 
    ISSN: 1432-1432
    Keywords: Synonymous substitutions ; Nonsynonymous substitutions ; Estimation methods ; Confidence intervals ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A method for estimating the numbers of synonymous (Ks) and nonsynonymous (Ka) substitutions per site is proposed. The method is based on the Li's (J Mol. Evol. 36:96–99, 1993) and Pamilo and Bianchi's (Mol. Biol. Evol. 10:271–281, 1993) method, but a putative source of bias is solved. It is proposed that the number of synonymous substitutions that are actually transitions or transversions should be computed by separating the twofold degenerate sites into two types of sites, 2S-fold and 2V-fold, where only transitional and transversional substitutions are synonymous, respectively. Kimura's (J. Mol. Evol. 16:111–120, 1980) two-parameter correcting method for multiple substitutions at a site is then applied using the overall observed synonymous transversion frequency to estimate both the numbers of synonymous transversional (Bs) and transitional (As) substitutions per site. This approach, therefore, also minimizes stochastic errors. Computer simulations indicate that the method presented gives more accurate Ks and Ka estimates than the aforementioned methods. Furthermore, the obtention of confidence intervals for divergence estimates by computer simulation is proposed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 47 (1998), S. 268-274 
    ISSN: 1432-1432
    Keywords: Key words: Synonymous codon usage bias — Estimation methods — Effective number of codons — Codon bias index — Codon adaptation index — ``Scaled'' χ2— Intrinsic codon bias index
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract. Synonymous codons are not generally used at equal frequencies, and this trend is observed for most genes and organisms. Several methods have been proposed and used to estimate the degree of the nonrandom use of the different synonymous codons. The estimates obtained by these methods, however, show different levels of both precision and dispersion when coding regions of a finite number of codons are under analysis. Here, we present a study, based on computer simulation, of how the different methods proposed to evaluate the nonrandom use of synonymous codons are affected by the length of the coding region analyzed. The results show that some of these methods are heavily influenced by the number of codons and that the comparison of codon usage bias between coding regions of different lengths shows a methodological bias under different conditions of nonrandom use of synonymous codons. The study of the dispersion of the estimates obtained by the different methods gives, on the other hand, an indication of the methods to be applied to compare values of codon usage bias among coding regions of equivalent length.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The brightness of type Ia supernovae, and their homogeneity as a class, makes them powerful tools in cosmology, yet little is known about the progenitor systems of these explosions. They are thought to arise when a white dwarf accretes matter from a companion star, is compressed and undergoes a ...
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 272 (2000), S. 109-112 
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A sample of O- and B-type stars with Hipparcos astrometric data, ages computed from Strömgren photometry and radial velocities, has been used to characterize the structure, age and kinematics of the Gould Belt system. The local spiral structure of our galaxy is determined from this sample, and also from a sample of Hipparcos Cepheid stars. The Gould Belt, with an orientation with respect to the galactic plane ofi G = 16-22° and ΩG =275-295°, extends up to a distance of 600 pc from the Sun. Roughly the 60-65% of the O and B stars younger than 60 Myr in the solar neighbourhood belong to this structure. Our results indicate that the kinematical behaviour of this system is complex, with an expansion motion in the solar neighbourhood (R〈300 pc).In the frame of the Lin's theory, and analysing the O and B stars further than 600 pc and the Cepheids, we found a galactic spiral structure characterized by a 4-arm spiral pattern with the Sun located atψ⊙ = 350-355 ± 30° – near the Sagittarius-Carina arm– and outside the corotation circle. The angular rotation speed of the spiral pattern was found to be Ωp = 31-32 ± 4 kms-1 kpc-1.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 1573-6857
    Keywords: protein evolution ; Drosophila ; synonymous ; nonsynonymous ; Index of Dispersion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rates of synonymous and nonsynonymous substitution were investigated for 24 genes in three Drosophila species, D. pseudoobscura, D. subobscura, and D. melanogaster. D. pseudoobscura and D. subobscura, two distantly related members of the obscura clade, differ on average by 0.29 synonymous nucleotide substitutions per site. D. melanogaster differs from the two obscura species by an average of 0.81 synonymous substitutions per site. Using a method developed by Gillespie, we investigated the variance to mean ratio, or Index of Dispersion, R, of substitutions along the three species' branches to test the fundamental prediction of the neutral theory of molecular evolution, E(R) = 1. For nonsynonymous substitutions, the average R, Ra is 1.6, which is not significantly different from the neutral theory prediction. Only 5 of the 24 genes had significantly large Ra valves, and 12 of the genes had Ra estimates of less than one. In contrast, the Index of Dispersion for synonymous substitutions was significantly large for 12 of the 24 genes, with an average of Rs = 4.4, also statistically significant. These findings contrast with results for mammals, which showed overdispersion of nonsynonymous substitutions, but not of synonymous substitutions. Weak selection acting to maintain codon bias in Drosophila, but not in mammals, may be important in explaining the high variance in the rate of synonymous substitutions in this group of organisms.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Springer
    International journal of infrared and millimeter waves 5 (1984), S. 585-604 
    ISSN: 1572-9559
    Keywords: infrared antennas ; point-contact non-linear devices...
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The electromagnetic coupling between a gaussian beam and whisker structures such as those found in some kinds of non-linear devices used at infrared frequencies is investigated. Calculations show the potential improvement of the electromagnetic coupling coefficient by the proper choice of the focusing angle of the beam and the use of corner reflectors, giving quantitative support to these techniques which have been used for long time.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 170 (1990), S. 263-265 
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Radial velocities of OB stars are utilised in order to determine the values of some galactic structure parameters in the solar neighbourhood.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Astrophysics and space science 187 (1992), S. 187-195 
    ISSN: 1572-946X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Some statistical studies on the nearby early-type stars proposed for observations by HIPPARCOS are presented. Results on spatial orientation and kinematics are in agreement with those found in the literature. An age estimate based on non-kinematical hypothesis is found to be somewhat smaller than expansion ages derives by some authors. Finally, it is suggested that Gould's Belt may have formed as a result of high-velocity cloud impact on the galactic disk, and some estimations are presented.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Publication Date: 2023-08-29
    Description: The data correspond to measurements along a vertical line of sight carried out by the multiwavelength Raman / elastic EARLINET/ACTRIS lidar at Universitat Politècnica de Catalunya (UPC, Barcelona, Spain) on March, 11th 2020 and on March 21th 2020. sensors-20210202T183221Z-001_Input_files are the raw data files in netCDF format generated by the multiwavelength Raman / elastic EARLINET/ACTRIS lidar at Universitat Politècnica de Catalunya (UPC, Barcelona, Spain) submitted as input to the EARLINET Single Calculus Chain (SCC, https://scc.imaa.cnr.it/) centralized software processing the data and retrieving, among other products, range-resolved aerosol extinction and backscatter coefficients. sensors-1074075_Output_ files contain the netCDF files containing the aerosol extinction and backscatter coefficients retrieved by the SCC.
    Keywords: ACTRIS-2; ACTRIS-IMP; Aerosol, Clouds and Trace Gases Research Infrastructure Implementation Project; Aerosols, Clouds, and Trace gases Research InfraStructure; Barcelona, Spain; Binary Object; Binary Object (File Size); Binary Object (Media Type); Development of GRASP radiative transfer code for the retrieval of aerosol microphysics vertical-profiles from space measurements and its impact in ACE mission; experiment; extinction retrieval; GRASP-ACE; Multiwavelength Raman /elastic LiDAR; pure-rotational lines; UPC; vibro-rotational lines
    Type: Dataset
    Format: text/tab-separated-values, 2 data points
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Publication Date: 2002-06-11
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...