5,190 research outputs found
Torsion free groups with indecomposable holonomy group I
We study the torsion free generalized crystallographic groups with the
indecomposable holonomy group which is isomorphic to either a cyclic group of
order or a direct product of two cyclic groups of order .Comment: 22 pages, AMS-Te
Recommended from our members
Improving Visual Field Examination of the Macula Using Structural Information
Purpose: To investigate a novel approach for structure-function modeling in glaucoma to improve visual field testing in the macula.
Methods: We acquired data from the macular region in 20 healthy eyes and 31 with central glaucomatous damage. Optical coherence tomography (OCT) scans were used to estimate the local macular ganglion cell density. Perimetry was performed with a fundus-tracking device using a 10-2 grid. OCT scans were matched to the retinal image from the fundus perimeter to accurately map the tested locations onto the structural damage. Binary responses from the subjects to all presented stimuli were used to calculate the structure-function model used to generate prior distributions for a ZEST (Zippy Estimation by Sequential Testing) Bayesian strategy. We used simulations based on structural and functional data acquired from an independent dataset of 20 glaucoma patients to compare the performance of this new strategy, structural macular ZEST (MacS-ZEST), with a standard ZEST.
Results: Compared to the standard ZEST, MacS-ZEST reduced the number of presentations by 13% in reliable simulated subjects and 14% with higher rates (≥20%) of false positive or false negative errors. Reduction in mean absolute error was not present for reliable subjects but was gradually more important with unreliable responses (≥10% at 30% error rate).
Conclusions: Binary responses can be modeled to incorporate detailed structural information from macular OCT into visual field testing, improving overall speed and accuracy in poor responders.
Translational Relevance: Structural information can improve speed and reliability for macular testing in glaucoma practice
The cool core state of Planck SZ-selected clusters versus X-ray selected samples: evidence for cool core bias
We characterized the population of galaxy clusters detected with the SZ
effect with Planck, by measuring the cool core state of the objects in a
well-defined subsample of the Planck catalogue. We used as indicator the
concentration parameter Santos et al. (2008). The fraction of cool core
clusters is and does not show significant indications of
evolution in the redshift range covered by our sample. We compare the
distribution of the concentration parameter in the Planck sample with the one
of the X-ray selected sample MACS (Mann & Ebeling, 2011): the distributions are
significantly different and the cool core fraction in MACS is much higher (). Since X-ray selected samples are known to be biased towards cool
cores due to the presence of their prominent surface brightness peak, we
simulated the impact of the "cool core bias" following Eckert et al. (2011). We
found that it plays a large role in the difference between the fractions of
cool cores in the two samples. We examined other selection effects that could
in principle bias SZ-surveys against cool cores but we found that their impact
is not sufficient to explain the difference between Planck and MACS. The
population of X-ray under-luminous objects, which are found in SZ-surveys but
missing in X-ray samples (Planck Collaboration 2016), could possibly contribute
to the difference, as we found most of them to be non cool cores, but this
hypothesis deserves further investigation.Comment: Accepted for publication in MNRA
A new formulation of oral viscous budesonide in treating of paediatric eosinophilic oesophagitis: a pilot study
OBJECTIVES:
Oral viscous budesonide is a recent therapeutic option for eosinophilic oesophagitis (EoE) compared with dietary restriction and inhaled steroids. This single-centre, open-label, not blinded study aims to evaluate the efficacy and safety of a new, preprepared oral viscous budesonide suspension (PVB) in children and adolescents with EoE.
METHODS:
We treated 36 children with PVB (29 boys; median age 12 years) with EoE diagnosed according to European Society for Paediatric Gastroenterology Hepatology and Nutrition guidelines. Patients <150 and >150 cm height received 2 and 4 mg PVB daily, respectively, for 12 weeks. Upper gastrointestinal endoscopy was performed at baseline, after 12 weeks of therapy and 24 weeks after the end of therapy. Baseline and post-treatment scores were calculated for symptoms, endoscopy, and histology. Serum cortisol was performed at baseline, 12, and 36 weeks.
RESULTS:
At the end of PVB trial, endoscopy showed macroscopic remission in 32 patients (88.9%), whereas at histology median pre- and post-treatment peak eosinophil count/high power field (HPF) markedly decreased from 42.2 (range: 15-100) to 2.9 (range: 0-30); moreover, mean symptom and histology scores impressively improved compared with baseline (P < 0.01). At 24 weeks after the end of PVB therapy, endoscopy showed oesophageal relapse in 21 patients (58.3%), whereas 15 (41.7%) were still in remission. Seven children (19.4%) with positive multichannel intraluminal impedance-pH were treated also with proton pump inhibitors. No significant difference between pre-/post-treatment morning cortisol levels occurred.
CONCLUSIONS:
The new PVB suspension presented in the present study is effective and safe for treating children with proven EoE. Larger placebo-controlled clinical trials would provide more information about dosing, efficacy, and long-term safety of this formulation, specifically designed for the oesophagus
Adapting water allocation management to drought scenarios
Climate change dynamics have significant consequences on water resources on a watershed scale. With water becoming scarcer and susceptible to variation, the planning and reallocation decisions in watershed management need to be reviewed. This research focuses on an in-depth understanding of the current allocation balance of water resources among competitors, placed along the course of the Adda River. In particular, during the summer period, the demand for water dramatically increases. This is due to the increase in irrigation activities in the lower part of the basin and to the highest peaks of tourist inflow, in the Como Lake and Valtellina areas. Moreover, during these months, the hydroelectric reservoirs in the upper part of the Adda River basin (the Valtellina) retain most of the volume of water coming from the snow and glacier melt. The existing allocation problem among these different competing users is exacerbated by the decreasing water supplies. The summer of 2003 testified the rise in a number of allocation problems and situations of water scarcity that brought about environmental and economical consequences. The RICLIC project is committed to the understanding of water dynamics on a regional scale, to quantify the volumes involved and offer local communities an instrument to improve a sustainable water management system, within uncertain climate change scenarios
Where does the gas fueling star formation in BCGs originate?
We investigate the relationship between X-ray cooling and star formation in
brightest cluster galaxies (BCGs). We present an X-ray spectral analysis of the
inner regions, 10-40 kpc, of six nearby cool core clusters (z<0.35) observed
with Chandra ACIS. This sample is selected on the basis of the high star
formation rate (SFR) observed in the BCGs. We restrict our search for cooling
gas to regions that are roughly cospatial with the starburst. We fit single-
and multi-temperature mkcflow models to constrain the amount of isobarically
cooling intracluster medium (ICM). We find that in all clusters, below a
threshold temperature ranging between 0.9 and 3 keV, only upper limits can be
obtained. In four out of six objects, the upper limits are significantly below
the SFR and in two, namely A1835 and A1068, they are less than a tenth of the
SFR. Our results suggests that a number of mechanisms conspire to hide the
cooling signature in our spectra. In a few systems the lack of a cooling
signature may be attributed to a relatively long delay time between the X-ray
cooling and the star burst. However, for A1835 and A1068, where the X-ray
cooling time is shorter than the timescale of the starburst, a possible
explanation is that the region where gas cools out of the X-ray phase extends
to very large radii, likely beyond the core of these systems.Comment: to appear in A&
- …