259 research outputs found
Tunable far infrared laser spectrometers
The state of the art in far infrared (FIR) spectroscopy is reviewed. The development of tunable, coherent FIR radiation sources is discussed. Applications of tunable FIR laser spectrometers for measurement of rotational spectra and dipole moments of molecular ions and free radicals, vibration-rotation-tunneling (VRT) spectra of weakly bound complexes, and vibration-rotation spectra of linear carbon clusters are presented. A detailed description of the Berkeley tunable FIR laser spectrometers is presented in the following article
The Berkeley tunable far infrared laser spectrometers
A detailed description is presented for a tunable far infrared laser spectrometer based on frequency mixing of an optically pumped molecular gas laser with tunable microwave radiation in a Schottky point contact diode. The system has been operated on over 30 laser lines in the range 10–100 cm^–1 and exhibits a maximum absorption sensitivity near one part in 10^6. Each laser line can be tuned by ±110 GHz with first-order sidebands. Applications of this instrument are detailed in the preceding paper
The Glueball Spectrum from a Potential Model
The spectrum of two-gluon glueballs below 3 GeV is investigated in a
potential model with dynamical gluon mass using variational method. The short
distance potential is approximated by one-gluon exchange, while the long
distance part is taken as a breakable string. The mass and size of the radial
as well as orbital excitations up to principle quantum number n=3 are
evaluated. The predicted mass ratios are compared with experimental and lattice
results.Comment: Revtex, 6 pages with 1 eps figur
Electronic and structural properties of vacancies on and below the GaP(110) surface
We have performed total-energy density-functional calculations using
first-principles pseudopotentials to determine the atomic and electronic
structure of neutral surface and subsurface vacancies at the GaP(110) surface.
The cation as well as the anion surface vacancy show a pronounced inward
relaxation of the three nearest neighbor atoms towards the vacancy while the
surface point-group symmetry is maintained. For both types of vacancies we find
a singly occupied level at mid gap. Subsurface vacancies below the second layer
display essentially the same properties as bulk defects. Our results for
vacancies in the second layer show features not observed for either surface or
bulk vacancies: Large relaxations occur and both defects are unstable against
the formation of antisite vacancy complexes. Simulating scanning tunneling
microscope pictures of the different vacancies we find excellent agreement with
experimental data for the surface vacancies and predict the signatures of
subsurface vacancies.Comment: 10 pages, 6 figures, Submitted to Phys. Rev. B, Other related
publications can be found at http://www.rz-berlin.mpg.de/th/paper.htm
Secondary somatic mutations restoring RAD51C and RAD51D associated with acquired resistance to the PARP inhibitor rucaparib in high-grade ovarian carcinoma
High-grade epithelial ovarian carcinomas (OC) containing mutated BRCA1 or BRCA2 (BRCA1/2) homologous recombination (HR) genes are sensitive to platinum-based chemotherapy and poly(ADP-ribose) polymerase inhibitors (PARPi), while restoration of HR function due to secondary mutations in BRCA1/2 has been recognized as an important resistance mechanism. We sequenced core HR pathway genes in 12 pairs of pre-treatment and post-progression tumor biopsy samples collected from patients in ARIEL2 Part 1, a phase 2 study of the PARPi rucaparib as treatment for platinum-sensitive, relapsed OC. In six of 12 pre-treatment biopsies, a truncation mutation in BRCA1, RAD51C or RAD51D was identified. In five of six paired post-progression biopsies, one or more secondary mutations restored the open reading frame. Four distinct secondary mutations and spatial heterogeneity were observed for RAD51C. In vitro complementation assays and a patient-derived xenograft (PDX), as well as predictive molecular modeling, confirmed that resistance to rucaparib was associated with secondary mutations
A Multicriteria Analysis on the Strategies to Open Taiwan's Mobile Virtual Network Operators Services
[[abstract]]This study investigates the trends followed by MVNOs (Mobile Virtual Network Operators) in the last three years and analyzes the strategies that can contribute to the success of Taiwan's telecommunications industry and marketing. We apply the method and concept of PATTERN (Planning Assistance Through Technical Evaluation of Relevance Number) to establish relevant systems for searching out the key successful factors of strategies to attract MVNOs. We also use the fuzzy Multi-Criteria Decision Making (MCDM) method for analyzing the different preference of a decision group in the criteria weights and for ranking the alternatives in a fuzzy environment in order to provide a strategy scheme. These results provide a reference to assist telecommunications operators, 3G license owners, potential MVNOs, and equipment manufacturers when working out business plans.[[incitationindex]]SCI[[booktype]]紙
A Characterization of Scale Invariant Responses in Enzymatic Networks
An ubiquitous property of biological sensory systems is adaptation: a step
increase in stimulus triggers an initial change in a biochemical or
physiological response, followed by a more gradual relaxation toward a basal,
pre-stimulus level. Adaptation helps maintain essential variables within
acceptable bounds and allows organisms to readjust themselves to an optimum and
non-saturating sensitivity range when faced with a prolonged change in their
environment. Recently, it was shown theoretically and experimentally that many
adapting systems, both at the organism and single-cell level, enjoy a
remarkable additional feature: scale invariance, meaning that the initial,
transient behavior remains (approximately) the same even when the background
signal level is scaled. In this work, we set out to investigate under what
conditions a broadly used model of biochemical enzymatic networks will exhibit
scale-invariant behavior. An exhaustive computational study led us to discover
a new property of surprising simplicity and generality, uniform linearizations
with fast output (ULFO), whose validity we show is both necessary and
sufficient for scale invariance of enzymatic networks. Based on this study, we
go on to develop a mathematical explanation of how ULFO results in scale
invariance. Our work provides a surprisingly consistent, simple, and general
framework for understanding this phenomenon, and results in concrete
experimental predictions
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