1,026 research outputs found
Constraining fundamental constants of physics with quasar absorption line systems
We summarize the attempts by our group and others to derive constraints on
variations of fundamental constants over cosmic time using quasar absorption
lines. Most upper limits reside in the range 0.5-1.5x10-5 at the 3sigma level
over a redshift range of approximately 0.5-2.5 for the fine-structure constant,
alpha, the proton-to-electron mass ratio, mu, and a combination of the proton
gyromagnetic factor and the two previous constants, gp(alpha^2/mu)^nu, for only
one claimed variation of alpha. It is therefore very important to perform new
measurements to improve the sensitivity of the numerous methods to at least
<0.1x10-5 which should be possible in the next few years. Future
instrumentations on ELTs in the optical and/or ALMA, EVLA and SKA pathfinders
in the radio will undoutedly boost this field by allowing to reach much better
signal-to-noise ratios at higher spectral resolution and to perform
measurements on molecules in the ISM of high redshift galaxies.Comment: 11 pages, 3 figure
Modelling the habitat of the endangered Carpentarian Grasswren (Amytornis dorotheae): The importance of spatio-temporal habitat availability in a fire prone landscape
Species distribution modelling (SDM), a tool increasingly adopted to quantify geographic range size, often predicts species’ distributions as static. However, habitat availability may exhibit spatial and temporal variation when dynamic processes, such as fire, determine suitability. Static SDM approaches may not satisfactorily represent this dynamic process. We investigated the potential use of SDM to quantify dynamic habitat availability by applying the MaxEnt SDM technique to model the habitat of the Carpentarian Grasswren (Amytornis dorotheae), an endangered Australian passerine dependent on long unburnt vegetation in a fire prone system. By adjusting a typical SDM approach to incorporate the dynamic nature of fire, we modelled the spatio-temporal variation of suitable habitat over 12 years and compared it to a static modelling approach. Incorporating fire as a dynamic process increased the importance of the fire variable to models (from 35% permutation importance) and improved model performance, as evaluated by the AUC using cross-validation. Our dynamic model revealed sizeable temporal variation in the area and spatial arrangement of suitable habitat that was not apparent in the static model. This result may partly solve the mystery of why the species occurs as widely separated populations despite the presence of seemingly suitable intervening habitat. In areas where the species is no longer found, habitat availability was less consistent due to frequent fire, and fire refugia was more limited and isolated, when compared to sites with recent records. These results demonstrate that, when compared to a static approach, a dynamic SDM approach can lead to improved understanding of dynamic ecological processes, and their impact on a species
Stringent bounds to spatial variations of the electron-to-proton mass ratio in the Milky Way
The ammonia method to probe variations of the electron-to-proton mass ratio,
Delta_mu/mu, is applied for the first time to dense prestellar molecular clouds
in the Milky Way. Carefully selected sample of 21 NH_3/CCS pairs observed in
the Perseus molecular cloud provide the offset Delta V (CCS-NH_3)=
36+/-7_{stat}+/-13.5_{sys} m/s . A similar offset of Delta V = 40.8 +/-
12.9_{stat} m/s between NH_3 (J,K) = (1,1) and N_2H+ J = 1-0 has been found in
an isolated dense core L183 by Pagani et al. (2009). Overall these observations
provide a safe bound of a maximum offset between ammonia and the other
molecules at the level of Delta V < 100 m/s. This bound corresponds to
Delta_mu/mu < 1E-7, which is an order of magnitude more sensitive than
available extragalactic constraints. Taken at face value the measured Delta V
shows positive shifts between the line centers of NH_3 and these two other
molecules and suggest a real offset, which would imply a Delta_mu/mu about
4E-8. If Delta_mu/mu follows the gradient of the local gravitational potential,
then the obtained results are in conflict with laboratory atomic clock
experiments in the solar system by 5 orders of magnitude, thus requiring a
chameleon-type scalar field model. New measurements involving other molecules
and a wider range of objects along with verification of molecular rest
frequencies are currently planned to confirm these first indications.Comment: 7 pages +2 figures. Galileo Galilei Institute Conferences on Dark
Matter and Dark Energ
Aneusomy of chromosomes 7 and 17 predicts the recurrence of transitional cell carcinoma of the urinary bladder
Objective To determine if changes in chromosome 7 and 17 copy number can be used to predict recurrence in patients with primary noninvasive (pTa) or superficially invasive (pT1) transitional cell carcinoma (TCC) of the urinary bladder. Patients and methods Tissue specimens for 129 tumours from 52 patients (38 men and 14 women) with pTa/pT1 TCC at first diagnosis were retrieved from pathology archives. All patient notes were accessed and disease outcome documented for superficial (pTa/ pT1) recurrence or progression to detrusor muscle invasion (greater than or equal to pT2). The rumours were examined for chromosomal copy number of chromosomes 7 and 17 using fluorescence in situ hybridization (PISH) with chromosome-specific probes. The copy number of chromosomes 7 and 17 was determined in interphase nuclei on intact 6 mu m tissue sections. Results Aneusomy of chromosomes 7 and 17 was detected in the index primary tumours of 10 of 32 (31%) patients with subsequent recurrent disease. No aneusomy for these chromosomes was detected in primary tumours from 20 patients with no detectable recurrence (P = 0.0082). The relative risk of recurrence was 3.62 times greater (95% confidence interval 1.6-8.1, Cox's multiple regression P = 0.0019) for patients with chromosomal aneusomy in primary TCC. Neither stage nor grade of the primary tumours was associated with recurrence in these patients, nor was there a significant association with increased grade (G2/3) or stage (greater than or equal to pT2) at recurrence. Conclusion These results suggest that the measurement of aneusomy by FISH, using markers for chromosomes 7 and 17, predict recurrence in a subgroup of patients with pTa/pT1 tumours at presentation. This finding may offer a new objective and quantitative test for patients destined to recur
Isotope shift calculations for atoms with one valence electron
This work presents a method for the ab initio calculation of isotope shift in
atoms and ions with one valence electron above closed shells. As a zero
approximation we use relativistic Hartree-Fock and then calculate correlation
corrections. The main motivation for developing the method comes from the need
to analyse whether different isotope abundances in early universe can
contribute to the observed anomalies in quasar absorption spectra. The current
best explanation for these anomalies is the assumption that the fine structure
constant, alpha, was smaller at early epoch. We test the isotope shift method
by comparing the calculated and experimental isotope shift for the alkali and
alkali-like atoms Na, MgII, K, CaII and BaII. The agreement is found to be
good. We then calculate the isotope shift for some astronomically relevant
transitions in SiII and SiIV, MgII, ZnII and GeII.Comment: 11 page
High Bone Mass is associated with bone-forming features of osteoarthritis in non-weight bearing joints independent of body mass index
Objectives: High Bone Mass (HBM) is associated with (a) radiographic knee osteoarthritis (OA), partly mediated by increased BMI, and (b) pelvic enthesophytes and hip osteophytes, suggestive of a bone-forming phenotype. We aimed to establish whether HBM is associated with radiographic features of OA in non weight-bearing (hand) joints, and whether such OA demonstrates a bone-forming phenotype. Methods: HBM cases (BMD Z-scores ≥+3.2) were compared with family controls. A blinded assessor graded all PA hand radiographs for: osteophytes (0-3), joint space narrowing (JSN)(0-3), subchondral sclerosis (0-1), at the index Distal Interphalangeal Joint (DIPJ) and 1st Carpometacarpal Joint (CMCJ), using an established atlas. Analyses used a random effects logistic regression model, adjusting a priori for age and gender. Mediating roles of BMI and bone turnover markers (BTMs) were explored by further adjustment. Results: 314 HBM cases (mean age 61.1years, 74% female) and 183 controls (54.3years, 46% female) were included. Osteophytes (grade≥1) were more common in HBM (DIPJ: 67% vs. 45%, CMCJ: 69% vs. 50%), with adjusted OR [95% CI] 1.82 [1.11, 2.97], p=0.017 and 1.89 [1.19, 3.01], p=0.007 respectively; no differences were seen in JSN. Further adjustment for BMI failed to attenuate ORs for osteophytes in HBM cases vs. controls; DIPJ 1.72 [1.05, 2.83], p=0.032, CMCJ 1.76 [1.00, 3.06], p=0.049. Adjustment for BTMs (concentrations lower amongst HBM cases) did not attenuate ORs. Conclusions: HBM is positively associated with OA in non weight-bearing joints, independent of BMI. HBMassociated OA is characterised by osteophytes, consistent with a bone-forming phenotype, rather than JSN reflecting cartilage loss. Systemic factors (e.g. genetic architecture) which govern HBM may also increase bone-forming OA risk
How emergency managers (mis?)interpret forecasts
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146849/1/disa12293.pd
Edoxaban vs. warfarin in patients with atrial fibrillation on amiodarone: a subgroup analysis of the ENGAGE AF-TIMI 48 trial
Background In the ENGAGE AF-TIMI 48 trial, the higher-dose edoxaban (HDE) regimen had a similar incidence of ischaemic stroke compared with warfarin, whereas a higher incidence was observed with the lower-dose regimen (LDE). Amiodarone increases edoxaban plasma levels via P-glycoprotein inhibition. The current pre-specified exploratory analysis was performed to determine the effect of amiodarone on the relative efficacy and safety profile of edoxaban. Methods and results At randomization, 2492 patients (11.8%) were receiving amiodarone. The primary efficacy endpoint of stroke or systemic embolic event was significantly lower with LDE compared with warfarin in amiodarone treated patients vs. patients not on amiodarone (hazard ratio [HR] 0.60, 95% confidence intervals [CIs] 0.36-0.99 and HR 1.20, 95% CI 1.03-1.40, respectively; P interaction <0.01). In patients randomized to HDE, no such interaction for efficacy was observed (HR 0.73, 95% CI 0.46-1.17 vs. HR 0.89, 95% CI 0.75-1.05, P interaction = 0.446). Major bleeding was similar in patients on LDE (HR 0.35, 95% CI 0.21-0.59 vs. HR 0.53, 95% CI 0.46-0.61, P interaction = 0.131) and HDE (HR 0.94, 95% CI 0.65-1.38 vs. HR 0.79, 95% CI 0.69-0.90, P interaction = 0.392) when compared with warfarin, independent of amiodarone use. Conclusions Patients randomized to the LDE treated with amiodarone at the time of randomization demonstrated a significant reduction in ischaemic events vs. warfarin when compared with those not on amiodarone, while preserving a favourable bleeding profile. In contrast, amiodarone had no effect on the relative efficacy and safety of HD
The IL-1RI co-receptor TILRR (FREM1 isoform 2) controls aberrant inflammatory responses and development of vascular disease
Summary
Expression of the interleukin-1 receptor type I (IL-1RI) co-receptor Toll-like and interleukin-1 receptor regulator (TILRR) is significantly increased in blood monocytes following myocardial infarction and in the atherosclerotic plaque, whereas levels in healthy tissue are low. TILRR association with IL-1RI at these sites causes aberrant activation of inflammatory genes, which underlie progression of cardiovascular disease. The authors show that genetic deletion of TILRR or antibody blocking of TILRR function reduces development of atherosclerotic plaques. Lesions exhibit decreased levels of monocytes, with increases in collagen and smooth muscle cells, characteristic features of stable plaques. The results suggest that TILRR may constitute a rational target for site- and signal-specific inhibition of vascular disease
and formfactors determined from a microscopic model for scattering
We determine the and formfactors from the
resp. partial wave of scattering by dressing corresponding
bare vertices with the help of non--pole contributions. The underlying
model is based on meson exchange, and involves nucleon and delta--isobar pole
and crossed--pole terms together with correlated --exchange in the
() and () channel. The results are very similar
for and and can be roughly parametrized by a monopole
with cutoff mass 500 MeV, with some variation due to model dependencies.
Thus the formfactors are much less soft than derived before for the
case by Saito and Afnan using the same procedure but different
interaction models.Comment: 7 pages, 4 postscript figure
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