579 research outputs found
Realization of the Three-dimensional Quantum Euclidean Space by Differential Operators
The three-dimensional quantum Euclidean space is an example of a
non-commutative space that is obtained from Euclidean space by -deformation.
Simultaneously, angular momentum is deformed to , it acts on the
-Euclidean space that becomes a -module algebra this way. In this
paper it is shown, that this algebra can be realized by differential operators
acting on functions on . On a factorspace of
a scalar product can be defined that leads to a
Hilbert space, such that the action of the differential operators is defined on
a dense set in this Hilbert space and algebraically self-adjoint becomes
self-adjoint for the linear operator in the Hilbert space. The self-adjoint
coordinates have discrete eigenvalues, the spectrum can be considered as a
-lattice.Comment: 13 pages, late
Structure of the Three-dimensional Quantum Euclidean Space
As an example of a noncommutative space we discuss the quantum 3-dimensional
Euclidean space together with its symmetry structure in great detail.
The algebraic structure and the representation theory are clarified and
discrete spectra for the coordinates are found. The q-deformed Legendre
functions play a special role. A completeness relation is derived for these
functions.Comment: 22 pages, late
IRAS 18511+0146: a proto Herbig Ae/Be cluster?
Context: The evolution of a young protocluster depends on the relative
spatial distributions and dynamics of both stars and gas. Aims: We study the
distribution and properties of the gas and stars surrounding the luminous (10^4
L_sun) protocluster IRAS 18511+0146. Methods: IRAS 18511+0146 and the cluster
associated with it has been investigated using the sub-millimetre (JCMT-SCUBA),
infrared (Spitzer-MIPSGAL, Spitzer-GLIMPSE, Palomar) and radio (VLA) continuum
data. Cluster simulations have been carried out in order to understand the
properties of clusters as well as to compare with the observations. Results:
The central most obscured part of the protocluster coincident with the compact
sub-millimetre source found with SCUBA is responsible for at least 2/3 of the
total luminosity. A number of cluster members have been identified which are
bright in mid infrared and show rising (near to mid infrared) spectral energy
distributions suggesting that these are very young stellar sources. In the mid
infrared 8.0 micron image, a number of filamentary structures and clumps are
detected in the vicinity of IRAS 18511+0146. Conclusions: Based on the
luminosity and cluster size as well as on the evolutionary stages of the
cluster members, IRAS 18511+0146 is likely to be protocluster with the most
massive object being a precursor to a Herbig type star.Comment: Accepted by the Astronomy and Astrophysics (23 Pages, 5 Tables, 12
Figures
Clec9a-mediated ablation of conventional dendritic cells suggests a lymphoid path to generating dendritic cells In Vivo
Conventional dendritic cells (cDCs) are versatile activators of immune responses that develop as part of the myeloid lineage downstream of hematopoietic stem cells. We have recently shown that in mice precursors of cDCs, but not of other leukocytes, are marked by expression of DNGR-1/CLEC9A. To genetically deplete DNGR-1-expressing cDC precursors and their progeny, we crossed Clec9a-Cre mice to Rosa-lox-STOP-lox-diphtheria toxin (DTA) mice. These mice develop signs of age-dependent myeloproliferative disease, as has been observed in other DC-deficient mouse models. However, despite efficient depletion of cDC progenitors in these mice, cells with phenotypic characteristics of cDCs populate the spleen. These cells are functionally and transcriptionally similar to cDCs in wild type control mice but show somatic rearrangements of Ig-heavy chain genes, characteristic of lymphoid origin cells. Our studies reveal a previously unappreciated developmental heterogeneity of cDCs and suggest that the lymphoid lineage can generate cells with features of cDCs when myeloid cDC progenitors are impaired
The host galaxies of three radio-loud quasars: 3C 48, 3C 345, and B2 1425+267
Observations with the Wide-Field/Planetary Camera-2 of the Hubble Space
Telescope (HST) are presented for three radio-loud quasars: 3C 48 (z=0.367), B2
1425+267 (z=0.366), and 3C 345 (z=0.594). All three quasars have luminous (~4
L^*) galaxies as hosts, which are either elliptical (B2 1425+267 and 3C 345) or
interacting (3C 48), and all hosts are 0.5 - 1.0 mag bluer in (V-I) than other
galaxies with the same overall morphology at similar redshifts to the quasars.
The host of 3C 48 has many H II regions and a very extended tidal tail.
All nine of the radio-loud quasars studied here and in Bahcall et al. (1997)
either have bright elliptical hosts or occur in interacting systems. There is a
robust correlation between the radio emission of the quasar and the luminosity
of host galaxy; the radio-loud quasars reside in galaxies that are on average
about 1 mag brighter than hosts of the radio-quiet quasars.Comment: Accepted for publication in ApJ. 3 postscript and 3 jpeg figures.
Original figures may be found in ftp://eku.sns.ias.edu/pub/sofia/RadioLoud
Reduction of time-resolved space-based CCD photometry developed for MOST Fabry Imaging data
The MOST (Microvariability & Oscillations of STars) satellite obtains
ultraprecise photometry from space with high sampling rates and duty cycles.
Astronomical photometry or imaging missions in low Earth orbits, like MOST, are
especially sensitive to scattered light from Earthshine, and all these missions
have a common need to extract target information from voluminous data cubes.
They consist of upwards of hundreds of thousands of two-dimensional CCD frames
(or sub-rasters) containing from hundreds to millions of pixels each, where the
target information, superposed on background and instrumental effects, is
contained only in a subset of pixels (Fabry Images, defocussed images,
mini-spectra). We describe a novel reduction technique for such data cubes:
resolving linear correlations of target and background pixel intensities. This
stepwise multiple linear regression removes only those target variations which
are also detected in the background. The advantage of regression analysis
versus background subtraction is the appropriate scaling, taking into account
that the amount of contamination may differ from pixel to pixel. The
multivariate solution for all pairs of target/background pixels is minimally
invasive of the raw photometry while being very effective in reducing
contamination due to, e.g., stray light. The technique is tested and
demonstrated with both simulated oscillation signals and real MOST photometry.Comment: 16 pages, 23 figure
A Broadband Study of Galactic Dust Emission
We have combined infrared data with HI, H2 and HII surveys in order to
spatially decompose the observed dust emission into components associated with
different phases of the gas. An inversion technique is applied. For the
decomposition, we use the IRAS 60 and 100 micron bands, the DIRBE 140 and 240
micron bands, as well as Archeops 850 and 2096 micron wavelengths. In addition,
we apply the decomposition to all five WMAP bands. We obtain longitude and
latitude profiles for each wavelength and for each gas component in carefully
selected Galactic radius bins.We also derive emissivity coefficients for dust
in atomic, molecular and ionized gas in each of the bins.The HI emissivity
appears to decrease with increasing Galactic radius indicating that dust
associated with atomic gas is heated by the ambient interstellar radiation
field (ISRF). By contrast, we find evidence that dust mixed with molecular
clouds is significantly heated by O/B stars still embedded in their progenitor
clouds. By assuming a modified black-body with emissivity law lambda^(-1.5), we
also derive the radial distribution of temperature for each phase of the gas.
All of the WMAP bands except W appear to be dominated by emission from
something other than normal dust, most likely a mixture of thermal
bremstrahlung from diffuse ionized gas, synchrotron emission and spinning dust.
Furthermore, we find indications of an emissivity excess at long wavelengths
(lambda > 850 micron) in the outer Galaxy (R > 8.9 kpc). This suggests either
the existence of a very cold dust component in the outer Galaxy or a
temperature dependence of the spectral emissivity index. Finally, it is shown
that ~ 80% of the total FIR luminosity is produced by dust associated with
atomic hydrogen, in agreement with earlier findings by Sodroski et al. (1997).Comment: accepted for publication by A&
First-line temozolomide combined with bevacizumab in metastatic melanoma: a multicentre phase II trial (SAKK 50/07)
Background: Oral temozolomide has shown similar efficacy to dacarbazine in phase III trials with median progression-free survival (PFS) of 2.1 months. Bevacizumab has an inhibitory effect on the proliferation of melanoma and sprouting endothelial cells. We evaluated the addition of bevacizumab to temozolomide to improve efficacy in stage IV melanoma. Patients and methods: Previously untreated metastatic melanoma patients with Eastern Cooperative Oncology Group performance status of two or more were treated with temozolomide 150 mg/m2 days 1-7 orally and bevacizumab 10 mg/kg body weight i.v. day 1 every 2 weeks until disease progression or unacceptable toxicity. The primary end point was disease stabilisation rate [complete response (CR), partial response (PR) or stable disease (SD)] at week 12 (DSR12); secondary end points were best overall response, PFS, overall survival (OS) and adverse events. Results: Sixty-two patients (median age 59 years) enrolled at nine Swiss centres. DSR12 was 52% (PR: 10 patients and SD: 22 patients). Confirmed overall response rate was 16.1% (CR: 1 patient and PR: 9 patients). Median PFS and OS were 4.2 and 9.6 months. OS (12.0 versus 9.2 months; P = 0.014) was higher in BRAF V600E wild-type patients. Conclusions: The primary end point was surpassed showing promising activity of this bevacizumab/temozolomide combination with a favourable toxicity profile. Response and OS were significantly higher in BRAF wild-type patient
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