769 research outputs found
Ehrenfest theorem, Galilean invariance and nonlinear Schr\"odinger equations
Galilean invariant Schr\"odinger equations possessing nonlinear terms
coupling the amplitude and the phase of the wave function can violate the
Ehrenfest theorem. An example of this kind is provided. The example leads to
the proof of the theorem: A Galilean invariant Schr\"odinger equation derived
from a lagrangian density obeys the Ehrenfest theorem. The theorem holds for
any linear or nonlinear lagrangian.Comment: Latex format, no figures, submitted to journal of physics
Ultraviolet and thermally stable polymer compositions
A class of polymers is provided, namely, poly(diarylsiloxy) arylazines. These polymers have a basic chemical composition which has the property of stabilizing the optical and physical properties of the polymer against the degradative effect of ultraviolet light and high temperatures. This stabilization occurs at wavelengths including those shorter than found on the surface of the earth and in the absence or presence of oxygen, making the polymers of the present invention useful for high performance coating applications in extraterrestrial space as well as similar applications in terrestrial service. The invention also provides aromatic azines which are useful in the preparation of polymers such as those of the present invention
Ultraviolet and thermally stable polymer compositions
A new class of polymers is provided, namely, poly (diarylsiloxy) arylazines. These novel polymers have a basic chemical composition which has the property of stabilizing the optical and physical properties of the polymer against the degradative effect of ultraviolet light and high temperatures. This stabilization occurs at wavelengths including those shorter than found on the surface of the earth and in the absence or presence of oxygen, making the polymers useful for high performance coating applications in extraterrestrial space as well as similar applications in terrestrial service. The invention also provides novel aromatic azines which are useful in the preparation of polymers such as those described
Ultraviolet and thermally stable polymer compositions
Copolymers, produced from aromatic substituted aromatic azine-siloxane compositions, are thermally stable, solar ultraviolet light non-degradable by wavelengths shorter than those reaching earth surface
Nonlinear interference in a mean-field quantum model
Using similar nonlinear stationary mean-field models for Bose-Einstein
Condensation of cold atoms and interacting electrons in a Quantum Dot, we
propose to describe the original many-particle ground state as a one-particle
statistical mixed state of the nonlinear eigenstates whose weights are provided
by the eigenstate non-orthogonality. We search for physical grounds in the
interpretation of our two main results, namely, quantum-classical nonlinear
transition and interference between nonlinear eigenstates.Comment: RevTeX (pdfLaTeX), 7 pages with 5 png-figures include
New Data on the Topside Electron Density Distribution
The existing uncertainties about the electron density profiles in the topside ionosphere, i.e., in the height region from hmF2 to approx. 2000 km, require the search for new data sources. The ISIS and Alouette topside sounder satellites from the sixties to the eighties recorded millions of ionograms and most were not analyzed in terms of electron density profiles. In recent years an effort started to digitize the analog recordings to prepare the ionograms for computerized analysis. As of November 2001 about 350,000 ionograms have been digitized from the original 7-track analog tapes. These data are available in binary and CDF format from the anonymous ftp site of the National Space Science Data Center. A search site and browse capabilities on CDAWeb assist the scientific usage of these data. All information and access links can be found at http://nssdc.gsfc.nasa.gov/space/isis/isis-status.html. This paper describes the ISIS data restoration effort and shows how the digital ionograms are automatically processed into electron density profiles from satellite orbit altitude (1400 km for ISIS-2) down to the F peak. Because of the large volume of data an automated processing algorithm is imperative. The automatic topside ionogram scaler with true height algorithm TOPIST software developed for this task is successfully scaling approx.70 % of the ionograms. An 'editing process' is available to manually scale the more difficult ionograms. The automated processing of the digitized ISIS ionograms is now underway, producing a much-needed database of topside electron density profiles for ionospheric modeling covering more than one solar cycle. The ISIS data restoration efforts are supported through NASA's Applied Systems and Information Research Program
Electon density profiles of the topside ionosphere
The existing uncertainties about the electron density profiles in the topside ionosphere, i.e., in the height region from h m F 2 to ~ 2000 km, require the search for new data sources. The ISIS and Alouette topside sounder satellites from the sixties to the eighties recorded millions of ionograms but most were not analyzed in terms of electron density profiles. In recent years an effort started to digitize the analog recordings to prepare the ionograms for computerized analysis. As of November 2001 about 350 000 ionograms have been digitized from the original 7-track analog tapes. These data are available in binary and CDF format from the anonymous ftp site of the National Space Science Data Center. A search site and browse capabilities on CDAWeb assist the scientific usage of these data. All information and access links can be found at http://nssdc.gsfc.nasa.gov/space/isis/isis-status. html. This paper describes the ISIS data restoration effort and shows how the digital ionograms are automatically processed into electron density profiles from satellite orbit altitude (1400 km for ISIS-2) down to the F peak. Because of the large volume of data an automated processing algorithm is imperative. The TOPside Ionogram Scaler with True height algorithm TOPIST software developed for this task is successfully scaling ~ 70% of the ionograms. An «editing process» is available to manually scale the more difficult ionograms. The automated processing of the digitized ISIS ionograms is now underway, producing a much-needed database of topside electron density profiles for ionospheric modeling covering more than one solar cycle
Identification of DeltaN isoform and polyadenylation site choice variants in molluscan p63/p73 -like homologues
Author Posting. © The Author(s), 2006. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Marine Biotechnology 9 (2007): 217-230, doi:10.1007/s10126-006-6045-1.The p53 family of transcription factors has been implicated in many vertebrate cancers. Altered p53 and p73 protein expression observed in leukemic cells of mollusks suggests that these transcription factors might be involved in invertebrate cancers as well. Here, we fully characterize the mRNA of four novel p53-like variants in the bivalve mollusks Mytilus trossulus (bay mussel) and Mytilus edulis (blue mussel). These species, widely used for environmental assessment, develop a haemic neoplasia (leukemia) that is frequently fatal. The correlation between expression of p53 and its close relative p73 and onset of molluskan leukemia was documented previously. We report the sequences of two distinct and novel p63/p73-like mRNAs, amplified by polymerase chain reaction (PCR) from both species. One of the p63/p73-like isoforms contains a 360 nt truncation in the 5' coding region. Based on this truncation and concomitant lack of a trans-activation (TA) domain, we designate this variant as a DeltaNp63/p73-like isoform: the first to be reported in an invertebrate species. In mammalian species, DeltaNp73 potently inhibits the tumor-suppressive function of p73 and p53, and its over-expression serves as a robust marker for mammalian cancer.
In addition, we report on the occurrence of alternate polyadenylation sites in the molluskan p63/p73: one proximal and one distal site, which differ by 1260 nt. We hypothesize that differential expression of various molluskan p63/p73-like isoforms, controlled in part by polyadenylation site choice variation, may help to interpret the apparently opposing roles of this gene in the development of cancer. Overall, this research further illustrates the utility of the molluskan model for studies involving the molecular mechanisms of oncogenesis in naturally occurring populations.
The data presented here require a revisiting of hypotheses regarding evolution of the p53 gene family. Current hypotheses indicate that 1) the protostome gene family does not contain an intronic promoter for DeltaN expression and 2) p53 gene duplication did not occur in protostomes. Our characterization of DeltaN p63/73 in mussel suggests that molluskan p53 gene family members have acquired an intronic promoter or splicing mechanism, either by invention that predates the evolutionary split of deuterostoms from protostomes, or by parallel evolution. Our data also show that Mytilus p53, p63/p73 and DeltaNp63/p73 are identical in their core regions with variation limited to their C- and N-terminals. This supports the notion that alternative splicing, intronic promoter usage and polyadenylation site choice may lead to expression of distinct isoforms originating from one common gene.A.F.M. was supported by the Greater Vancouver Regional District, BC, Canada and a Collaborative Research and Development Grant from the Natural Science and Engineering Research Council of Canada (#CRDP J 323120 –05). R.L.C. was supported by Environmental Protection Agency grant # R82935901 and National Institute of Health grant #1R21ES012273-01
Terrestrial Myriametric Radio Burst Observed by IMAGE and Geotail Satellites
We report IMAGE and Geotail simultaneous observations of a terrestrial myriametric radio burst (TMRB) detected on August 19, 2001. The TMRB was confined in time (0830-1006 UT) and frequency (12-50 kHz), suggesting a fan beam-like emission pattern from a single discrete source. Analysis and comparisons with existing TMR radiations strongly suggest that the TMRB is a distinct emission perhaps resulting from dayside magnetic reconnection instigated by northward interplanetary field condition
Systematic evaluation of clinical predictors of aggressive ulcerative colitis
Background: Studies evaluating risk factors associated with an "aggressive" disease course in ulcerative colitis (UC) are scarce. A recent definition of "aggressive" UC incorporated the following
characteristics: 1) high relapse rate, 2) need for surgery, 3) development of colorectal cancer, and 4) presence of extraintestinal manifestations (EIM). The following factors for an aggressive / disabling disease course in UC have been identified so far: age < 40 years at S140 Poster presentations UC diagnosis, pancolitis, concomitant primary sclerosing cholangitis, and deep ulcerations of the colonic mucosa. We aimed to evaluate risk factors for an "aggressive" disease course in UC patients.
Methods: Data from the Swiss IBD cohort study were analyzed. Patients were recruited from university centers (80%), regional hospitals (19%), and private practices (1%). We applied the following definition for "aggressive" UC: 1) patients ever treated with TNFantagonists or calcineurin inhibitors (tacrolimus / cyclosporine), and 2) need for (procto)-colectomy. Non-normal data are presented as median and interquartile range [IQR]
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