2,084 research outputs found
Increasing biological complexity is positively correlated with the relative genome-wide expansion of non-protein-coding DNA sequences
Background: Prior to the current genomic era it was suggested that the number
of protein-coding genes that an organism made use of was a valid measure of its
complexity. It is now clear, however, that major incongruities exist and that
there is only a weak relationship between biological complexity and the number
of protein coding genes. For example, using the protein-coding gene number as a
basis for evaluating biological complexity would make urochordates and insects
less complex than nematodes, and humans less complex than rice. Results: We
analyzed the ratio of noncoding to total genomic DNA (ncDNA/tgDNA) for 85
sequenced species and found that this ratio correlates well with increasing
biological complexity. The ncDNA/tgDNA ratio is generally contained within the
bandwidth of 0.05-0.24 for prokaryotes, but rises to 0.26-0.52 in unicellular
eukaryotes, and to 0.62-0.985 for developmentally complex multicellular
organisms. Significantly, prokaryotic species display a non-uniform species
distribution approaching the mean of 0.1177 ncDNA/tgDNA (p=1.58 x 10^-13), and
a nonlinear ncDNA/tgDNA relationship to genome size (r=0.15). Importantly, the
ncDNA/tgDNA ratio corrects for ploidy, and is not substantially affected by
variable loads of repetitive sequences. Conclusions: We suggest that the
observed noncoding DNA increases and compositional patterns are primarily a
function of increased information content. It is therefore possible that
introns, intergenic sequences, repeat elements, and genomic DNA previously
regarded as genetically inert may be far more important to the evolution and
functional repertoire of complex organisms than has been previously
appreciated.Comment: 25 pages, 2 figures, 1 tabl
Mechanism facilitates coating of inner surfaces of metal cylinders
Cylinder is rotated about shielded hot filament to vapor deposit thin coatings of aluminum or other metallic substances on the inner surface of a cylinder while avoiding heat-producing high-density current flow which causes outgassing of the coating surface. This method is acceptable for glass or metal
Applications of control theory
Applications of control theory are considered in the areas of decoupling and wake steering control of submersibles, a method of electrohydraulic conversion with no moving parts, and socio-economic system modelling
Mapping the Evolution of Optically-Generated Rotational Wavepackets in a Room Temperature Ensemble of D
A coherent superposition of rotational states in D has been excited by
nonresonant ultrafast (12 femtosecond) intense (2 10
Wcm) 800 nm laser pulses leading to impulsive dynamic alignment.
Field-free evolution of this rotational wavepacket has been mapped to high
temporal resolution by a time-delayed pulse, initiating rapid double
ionization, which is highly sensitive to the angle of orientation of the
molecular axis with respect to the polarization direction, . The
detailed fractional revivals of the neutral D wavepacket as a function of
and evolution time have been observed and modelled theoretically.Comment: 4 pages, 3 figures. Accepted for publication in Phys. Rev. A. Full
reference to follow.
Controlling Silver Nanoparticle Size and Morphology with Photostimulated Synthesis
Photo-induced synthesis and control over the size and shape of colloidal
silver nanoparticles is investigated in contrast to photo-stimulated
aggregation of small nanoparticles into large fractal-type structures. The
feasibility of light-driven nanoengineering which enables manipulation of the
sizes and shapes of the isolated nanoparticles is studied by varying the amount
and type of the stabilizing agent and the type of optical irradiation.Comment: 10 pages, 7 figures, 11 image
The Age of the Inner Halo Globular Cluster NGC 6652
HST (V,I) photometry has been obtained for the inner halo globular cluster
NGC 6652. The photometry reaches approximately 4 mag below the turn-off and
includes a well populated horizontal branch. This cluster is located close to
the Galactic center at a galactocentric distance of approximately 2.0 kpc with
a reddening of E(V-I) = 0.15 +/- 0.02 and has a metallicity of [Fe/H]
approximately -0.85. Based upon Delta(V) between the point on the sub-giant
branch which is 0.05 mag redder than the turn-off and the horizontal branch,
NGC 6652 is 11.7 +/- 1.6 Gyr old. Using this same Delta(V), precise
differential ages for 47 Tuc (a thick disk globular), M107 and NGC 1851 (both
halo clusters) were obtained. NGC 6652 appears to be the same age as 47 Tuc and
NGC 1851 (within +/- 1.2 Gyr), while there is a slight suggestion that M107 is
older than NGC 6652 by 2.3 +/- 1.5 Gyr. As this is a less than 2-sigma result,
this issue needs to be investigated further before a definitive statement
regarding the relative age of M107 and NGC 6652 may be made.Comment: accepted for publication in the Astronomical Journal, December 2000
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New Perspectives in Sinographic Language Processing Through the Use of Character Structure
Chinese characters have a complex and hierarchical graphical structure
carrying both semantic and phonetic information. We use this structure to
enhance the text model and obtain better results in standard NLP operations.
First of all, to tackle the problem of graphical variation we define
allographic classes of characters. Next, the relation of inclusion of a
subcharacter in a characters, provides us with a directed graph of allographic
classes. We provide this graph with two weights: semanticity (semantic relation
between subcharacter and character) and phoneticity (phonetic relation) and
calculate "most semantic subcharacter paths" for each character. Finally,
adding the information contained in these paths to unigrams we claim to
increase the efficiency of text mining methods. We evaluate our method on a
text classification task on two corpora (Chinese and Japanese) of a total of 18
million characters and get an improvement of 3% on an already high baseline of
89.6% precision, obtained by a linear SVM classifier. Other possible
applications and perspectives of the system are discussed.Comment: 17 pages, 5 figures, presented at CICLing 201
The Dwarf Spheroidal Companions to M31: Variable Stars in Andromeda VI
We have surveyed Andromeda VI, a dwarf spheroidal galaxy companion to M31,
for variable stars using F450W and F555W observations obtained with the Hubble
Space Telescope. A total of 118 variables were found, with 111 being RR Lyrae,
6 anomalous Cepheids, and 1 variable we were unable to classify. We find that
the Andromeda VI anomalous Cepheids have properties consistent with those of
anomalous Cepheids in other dwarf spheroidal galaxies. We revise the existing
period-luminosity relations for these variables. Further, using these and other
available data, we show that there is no clear difference between fundamental
and first-overtone anomalous Cepheids in a period-amplitude diagram at shorter
periods, unlike the RR Lyrae. For the Andromeda VI RR Lyrae, we find that they
lie close to the Oosterhoff type I Galactic globular clusters in the
period-amplitude diagram, although the mean period of the RRab stars, =
0.588 d, is slightly longer than the typical Oosterhoff type I cluster. The
mean V magnitude of the RR Lyrae in Andromeda VI is 25.29+/-0.03, resulting in
a distance 815+/-25 kpc on the Lee, Demarque, & Zinn distance scale. This is
consistent with the distance derived from the I magnitude of the tip of the red
giant branch. Similarly, the properties of the RR Lyrae indicate a mean
abundance for Andromeda VI which is consistent with that derived from the mean
red giant branch color.Comment: 23 pages, including 13 figures and 6 tables, emulateapj5/apjfonts
style. Accepted by the Astronomical Journal. We recommend the interested
reader to download the preprint with full-resolution figures, which can be
found at http://www.noao.edu/noao/staff/pritzl/M31dwarfs.htm
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