171 research outputs found
Low-dimensional Singularities with Free Divisors as Discriminants
We present versal complex analytic families, over a smooth base and of fibre
dimension zero, one, or two, where the discriminant constitutes a free divisor.
These families include finite flat maps, versal deformations of reduced curve
singularities, and versal deformations of Gorenstein surface singularities in
C^5. It is shown that such free divisors often admit a "fast normalization",
obtained by a single application of the Grauert-Remmert normalization
algorithm. For a particular Gorenstein surface singularity in C^5, namely the
simple elliptic singularity of type \tilde A_4, we exhibit an explicit
discriminant matrix and show that the slice of the discriminant for a fixed
j-invariant is the cone over the dual variety of an elliptic curve.Comment: 29 pages, misprints and references correcte
SYSTOMONAS — an integrated database for systems biology analysis of Pseudomonas
To provide an integrated bioinformatics platform for a systems biology approach to the biology of pseudomonads in infection and biotechnology the database SYSTOMONAS (SYSTems biology of pseudOMONAS) was established. Besides our own experimental metabolome, proteome and transcriptome data, various additional predictions of cellular processes, such as gene-regulatory networks were stored. Reconstruction of metabolic networks in SYSTOMONAS was achieved via comparative genomics. Broad data integration is realized using SOAP interfaces for the well established databases BRENDA, KEGG and PRODORIC. Several tools for the analysis of stored data and for the visualization of the corresponding results are provided, enabling a quick understanding of metabolic pathways, genomic arrangements or promoter structures of interest. The focus of SYSTOMONAS is on pseudomonads and in particular Pseudomonas aeruginosa, an opportunistic human pathogen. With this database we would like to encourage the Pseudomonas community to elucidate cellular processes of interest using an integrated systems biology strategy. The database is accessible at
STAGES: the Space Telescope A901/2 Galaxy Evolution Survey
We present an overview of the Space Telescope A901/2 Galaxy Evolution Survey
(STAGES). STAGES is a multiwavelength project designed to probe physical
drivers of galaxy evolution across a wide range of environments and luminosity.
A complex multi-cluster system at z~0.165 has been the subject of an 80-orbit
F606W HST/ACS mosaic covering the full 0.5x0.5 (~5x5 Mpc^2) span of the
supercluster. Extensive multiwavelength observations with XMM-Newton, GALEX,
Spitzer, 2dF, GMRT, and the 17-band COMBO-17 photometric redshift survey
complement the HST imaging. Our survey goals include simultaneously linking
galaxy morphology with other observables such as age, star-formation rate,
nuclear activity, and stellar mass. In addition, with the multiwavelength
dataset and new high resolution mass maps from gravitational lensing, we are
able to disentangle the large-scale structure of the system. By examining all
aspects of environment we will be able to evaluate the relative importance of
the dark matter halos, the local galaxy density, and the hot X-ray gas in
driving galaxy transformation. This paper describes the HST imaging, data
reduction, and creation of a master catalogue. We perform Sersic fitting on the
HST images and conduct associated simulations to quantify completeness. In
addition, we present the COMBO-17 photometric redshift catalogue and estimates
of stellar masses and star-formation rates for this field. We define galaxy and
cluster sample selection criteria which will be the basis for forthcoming
science analyses, and present a compilation of notable objects in the field.
Finally, we describe the further multiwavelength observations and announce
public access to the data and catalogues.Comment: 29 pages, 22 figures; accepted to MNRAS. Full data release available
at http://www.nottingham.ac.uk/astronomy/stage
Five-year results of cervical disc prostheses in the SWISSspine registry
Background: The Swiss Federal Office of Public Health demanded a nationwide HTA-registry for cervical total disc arthroplasty (TDA), to decide about its reimbursement. The goal of the SWISSspine registry is to generate evidence about the safety and efficiency of cervical TDA. Materials and methods: Three hundred thirty-two cases treated between 3.2005 and 6.2006 who were eligible for 5years follow-ups were included in the study. Follow-up rates for 3-6months, 1, 2 and 5years were 84.6, 74.4, 50.6 and 64.8%, respectively. Outcome measures were neck and arm pain, medication, quality of life, intraoperative and postoperative complication and revision rates. In addition, segmental mobility, ossification, adjacent and distant segment degeneration were analyzed at the 5-year follow-up. Results: There was significant, clinically relevant and lasting reduction of neck (preop/postop 60/21 VAS points) and arm pain (preop/postop VAS 67/17) and a consequently decreased analgesics consumption and quality of life improvement (preop/postop 0.39/0.82 EQ-5D points) until the 5-year follow-up. The rates for intraoperative and early postoperative complications were 0.6 and 7.2%, respectively. In 0.6% an early and in 3.9% a late revision surgery was performed. At the 5-year follow-up, the average range of motion of the mobile segments (88.2%) was 10.2°. In 40.7% of the patients osteophytes at least potentially affecting range of motion were seen. Conclusions: Cervical TDA appeared as safe and efficient in long-term pain alleviation, consequent reduction of pain killer consumption and in improvement of quality of life. The improvement is stable over the 5years postoperative period. The vast majority of treated segments remained mobile after 5years, although 40.7% of patients showed osteophyte
Upper limits on the strength of periodic gravitational waves from PSR J1939+2134
The first science run of the LIGO and GEO gravitational wave detectors
presented the opportunity to test methods of searching for gravitational waves
from known pulsars. Here we present new direct upper limits on the strength of
waves from the pulsar PSR J1939+2134 using two independent analysis methods,
one in the frequency domain using frequentist statistics and one in the time
domain using Bayesian inference. Both methods show that the strain amplitude at
Earth from this pulsar is less than a few times .Comment: 7 pages, 1 figure, to appear in the Proceedings of the 5th Edoardo
Amaldi Conference on Gravitational Waves, Tirrenia, Pisa, Italy, 6-11 July
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Improving the sensitivity to gravitational-wave sources by modifying the input-output optics of advanced interferometers
We study frequency dependent (FD) input-output schemes for signal-recycling
interferometers, the baseline design of Advanced LIGO and the current
configuration of GEO 600. Complementary to a recent proposal by Harms et al. to
use FD input squeezing and ordinary homodyne detection, we explore a scheme
which uses ordinary squeezed vacuum, but FD readout. Both schemes, which are
sub-optimal among all possible input-output schemes, provide a global noise
suppression by the power squeeze factor, while being realizable by using
detuned Fabry-Perot cavities as input/output filters. At high frequencies, the
two schemes are shown to be equivalent, while at low frequencies our scheme
gives better performance than that of Harms et al., and is nearly fully
optimal. We then study the sensitivity improvement achievable by these schemes
in Advanced LIGO era (with 30-m filter cavities and current estimates of
filter-mirror losses and thermal noise), for neutron star binary inspirals, and
for narrowband GW sources such as low-mass X-ray binaries and known radio
pulsars. Optical losses are shown to be a major obstacle for the actual
implementation of these techniques in Advanced LIGO. On time scales of
third-generation interferometers, like EURO/LIGO-III (~2012), with
kilometer-scale filter cavities, a signal-recycling interferometer with the FD
readout scheme explored in this paper can have performances comparable to
existing proposals. [abridged]Comment: Figs. 9 and 12 corrected; Appendix added for narrowband data analysi
Comparison of Skeletal Effects of Ovariectomy Versus Chemically Induced Ovarian Failure in Mice
Bone loss associated with menopause leads to an increase in skeletal fragility and fracture risk. Relevant animal models can be useful for evaluating the impact of ovarian failure on bone loss. A chemically induced model of menopause in which mice gradually undergo ovarian failure yet retain residual ovarian tissue has been developed using the chemical 4-vinylcyclohexene diepoxide (VCD). This study was designed to compare skeletal effects of VCD-induced ovarian failure to those associated with ovariectomy (OVX). Young (28 day) C57Bl/6Hsd female mice were dosed daily with vehicle or VCD (160 mg/kg/d, IP) for 15 days (n = 6–7/group) and monitored by vaginal cytology for ovarian failure. At the mean age of VCD-induced ovarian failure (∼6 wk after onset of dosing), a different group of mice was ovariectomized (OVX, n = 8). Spine BMD (SpBMD) was measured by DXA for 3 mo after ovarian failure and OVX. Mice were killed ∼5 mo after ovarian failure or OVX, and bone architecture was evaluated by μCT ex vivo. In OVX mice, SpBMD was lower than controls 1 mo after OVX, whereas in VCD-treated mice, SpBMD was not lower than controls until 2.9 mo after ovarian failure (p < 0.05). Both VCD-induced ovarian failure and OVX led to pronounced deterioration of trabecular bone architecture, with slightly greater effects in OVX mice. At the femoral diaphysis, cortical bone area and thickness did not differ between VCD mice and controls but were decreased in OVX compared with both groups (p < 0.05). Circulating androstenedione levels were preserved in VCD-treated mice but reduced in OVX mice relative to controls (p < 0.001). These findings support that (1) VCD-induced ovarian failure leads to trabecular bone deterioration, (2) bone loss is attenuated by residual ovarian tissue, particularly in diaphyseal cortical bone, and (3) the VCD mouse model can be a relevant model for natural menopause in the study of associated bone disorders
A comparison of the strength of biodiversity effects across multiple functions
In order to predict which ecosystem functions are most at risk from biodiversity loss, meta-analyses have generalised results from biodiversity experiments over different sites and ecosystem types. In contrast, comparing the strength of biodiversity effects across a large number of ecosystem processes measured in a single experiment permits more direct comparisons. Here, we present an analysis of 418 separate measures of 38 ecosystem processes. Overall, 45% of processes were significantly affected by plant species richness, suggesting that, while diversity affects a large number of processes not all respond to biodiversity. We therefore compared the strength of plant diversity effects between different categories of ecosystem processes, grouping processes according to the year of measurement, their biogeochemical cycle, trophic level and compartment (above- or belowground) and according to whether they were measures of biodiversity or other ecosystem processes, biotic or abiotic and static or dynamic. Overall, and for several individual processes, we found that biodiversity effects became stronger over time. Measures of the carbon cycle were also affected more strongly by plant species richness than were the measures associated with the nitrogen cycle. Further, we found greater plant species richness effects on measures of biodiversity than on other processes. The differential effects of plant diversity on the various types of ecosystem processes indicate that future research and political effort should shift from a general debate about whether biodiversity loss impairs ecosystem functions to focussing on the specific functions of interest and ways to preserve them individually or in combinatio
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