64 research outputs found
An approach to implementing dynamic adaptation in c
This paper describes TRAP/C++, a software tool that enables new adaptable behavior to be added to existing C++ programs in a transparent fashion. In previous investigations, we used an aspectoriented approach to manually define aspects for adaptation infrastructure, which were woven into the original application code at compile time. In follow-on work, we developed TRAP, a transparent shaping technique for automatically generating adaptation aspects, where TRAP/J is a specific instantiation of TRAP. This paper presents our work into building TRAP/C++, which was intended to be a port of TRAP/J into C++. Designing TRAP/C++ required us to overcome two major hurdles: lack of reflection in C++ and the incompatibility between the management of objects in C++ and the aspect weaving technique used in TRAP/J. We used generative programming methods to produce two tools, TrapGen and TrapCC, that work together to produce the desired TRAP/C++ functionality. Details of the TRAP/C++ architecture and operation are presented, which we illustrate with a description of a case study that adds dynamic auditing capabilities to an existing distributed C++ application
Towards a Stable Numerical Evolution of Strongly Gravitating Systems in General Relativity: The Conformal Treatments
We study the stability of three-dimensional numerical evolutions of the
Einstein equations, comparing the standard ADM formulation to variations on a
family of formulations that separate out the conformal and traceless parts of
the system. We develop an implementation of the conformal-traceless (CT)
approach that has improved stability properties in evolving weak and strong
gravitational fields, and for both vacuum and spacetimes with active coupling
to matter sources. Cases studied include weak and strong gravitational wave
packets, black holes, boson stars and neutron stars. We show under what
conditions the CT approach gives better results in 3D numerical evolutions
compared to the ADM formulation. In particular, we show that our implementation
of the CT approach gives more long term stable evolutions than ADM in all the
cases studied, but is less accurate in the short term for the range of
resolutions used in our 3D simulations.Comment: 17 pages, 15 figures. Small changes in the text, and a change in the
list of authors. One new reference adde
Non-perturbative measurement of low-intensity charged particle beams
Non-perturbative measurements of low-intensity charged particle beams are particularly challenging to beam diagnostics due to the low amplitude of the induced electromagnetic fields. In the low-energy antiproton decelerator (AD) and the future extra low energy antiproton rings at CERN, an absolute measurement of the beam intensity is essential to monitor the operation efficiency. Superconducting quantum interference device (SQUID) based cryogenic current comparators (CCC) have been used for measuring slow charged beams in the nA range, showing a very good current resolution. But these were unable to measure fast bunched beams, due to the slew-rate limitation of SQUID devices and presented a strong susceptibility to external perturbations. Here, we present a CCC system developed for the AD machine, which was optimised in terms of its current resolution, system stability, ability to cope with short bunched beams, and immunity to mechanical vibrations. This paper presents the monitor design and the first results from measurements with a low energy antiproton beam obtained in the AD in 2015. These are the first CCC beam current measurements ever performed in a synchrotron machine with both coasting and short bunched beams. It is shown that the system is able to stably measure the AD beam throughout the entire cycle, with a current resolution of
Auditory network connectivity in tinnitus patients: a resting-state fMRI study
Objective: Resting-state functional magnetic resonance imaging (fMRI) uncovers correlated activity between spatially distinct functionally related brain regions and offers clues about the integrity of functional brain circuits in people with chronic subjective tinnitus. We chose to investigate auditory network connectivity, adopting and extending previously used analyses methods to provide an independent evaluation of replicability. Design: Independent components analysis (ICA) was used to identify coherent patterns arising from spontaneous brain signals within the resting-state data. The auditory network component was extracted and evaluated. Bivariate and partial correlation analyses were performed on pre-defined regions of bilateral auditory cortex to assess functional connectivity. Study sample: Our design carefully matched participant groups for possible confounds, such as hearing status. Twelve patients (seven male, five female; mean age 66 years) all with chronic constant tinnitus and eleven controls (eight male, three female; mean age 68 years) took part. Results: No significant differences were found in auditory network connectivity between groups after correcting for multiple statistical comparisons in the analysis. This contradicts previous findings reporting reduced auditory network connectivity; albeit at a less stringent statistical threshold. Conclusions: Auditory network connectivity does not appear to be reliably altered by the experience of chronic subjective tinnitus
Search for Dark Matter Axions with CAST-CAPP
The CAST-CAPP axion haloscope, operating at CERN inside the CAST dipole
magnet, has searched for axions in the 19.74 eV to 22.47 eV mass
range. The detection concept follows the Sikivie haloscope principle, where
Dark Matter axions convert into photons within a resonator immersed in a
magnetic field. The CAST-CAPP resonator is an array of four individual
rectangular cavities inserted in a strong dipole magnet, phase-matched to
maximize the detection sensitivity. Here we report on the data acquired for
4124 h from 2019 to 2021. Each cavity is equipped with a fast frequency tuning
mechanism of 10 MHz/min between 4.774 GHz and 5.434 GHz. In the present work,
we exclude axion-photon couplings for virialized galactic axions down to
at the 90% confidence
level. The here implemented phase-matching technique also allows for future
large-scale upgrades.Comment: 24 pages, 5 figures, Published version available with Open Access at
https://www.nature.com/articles/s41467-022-33913-
First results of the CAST-RADES haloscope search for axions at 34.67 µeV
We present results of the Relic Axion Dark-Matter Exploratory Setup (RADES), a detector which is part of the CERN Axion Solar Telescope (CAST), searching for axion dark matter in the 34.67 µeV mass range. A radio frequency cavity consisting of 5 sub-cavities coupled by inductive irises took physics data inside the CAST dipole magnet for the first time using this filter-like haloscope geometry. An exclusion limit with a 95% credibility level on the axion-photon coupling constant of ga¿ ¿ 4 × 10-13 GeV-1 over a mass range of 34.6738 µeV < ma< 34.6771 µeV is set. This constitutes a significant improvement over the current strongest limit set by CAST at this mass and is at the same time one of the most sensitive direct searches for an axion dark matter candidate above the mass of 25 µeV. The results also demonstrate the feasibility of exploring a wider mass range around the value probed by CAST-RADES in this work using similar coherent resonant cavities. © 2021, The Author(s)
Safety and tolerability of sitagliptin in clinical studies: a pooled analysis of data from 10,246 patients with type 2 diabetes
<p>Abstract</p> <p>Background</p> <p>In a previous pooled analysis of 12 double-blind clinical studies that included data on 6,139 patients with type 2 diabetes, treatment with sitagliptin, a dipeptidyl peptidase-4 (DPP-4) inhibitor, was shown to be generally well tolerated compared with treatment with control agents. As clinical development of sitagliptin continues, additional studies have been completed, and more patients have been exposed to sitagliptin. The purpose of the present analysis is to update the safety and tolerability assessment of sitagliptin by pooling data from 19 double-blind clinical studies.</p> <p>Methods</p> <p>The present analysis included data from 10,246 patients with type 2 diabetes who received either sitagliptin 100 mg/day (N = 5,429; sitagliptin group) or a comparator agent (placebo or an active comparator) (N = 4,817; non-exposed group). The 19 studies from which this pooled population was drawn represent the double-blind, randomized studies that included patients treated with the usual clinical dose of sitagliptin (100 mg/day) for between 12 weeks and 2 years and for which results were available as of July 2009. These 19 studies assessed sitagliptin taken as monotherapy, initial combination therapy with metformin or pioglitazone, or as add-on combination therapy with other antihyperglycemic agents (metformin, pioglitazone, a sulfonylurea ± metformin, insulin ± metformin, or rosiglitazone + metformin). Patients in the non-exposed group were taking placebo, metformin, pioglitazone, a sulfonylurea ± metformin, insulin ± metformin, or rosiglitazone + metformin. The analysis used patient-level data from each study to evaluate between-group differences in the exposure-adjusted incidence rates of adverse events.</p> <p>Results</p> <p>Summary measures of overall adverse events were similar in the sitagliptin and non-exposed groups, except for an increased incidence of drug-related adverse events in the non-exposed group. Incidence rates of specific adverse events were also generally similar between the two groups, except for increased incidence rates of hypoglycemia, related to the greater use of a sulfonylurea, and diarrhea, related to the greater use of metformin, in the non-exposed group and constipation in the sitagliptin group. Treatment with sitagliptin was not associated with an increased risk of major adverse cardiovascular events.</p> <p>Conclusions</p> <p>In this updated pooled safety analysis of data from 10,246 patients with type 2 diabetes, sitagliptin 100 mg/day was generally well tolerated in clinical trials of up to 2 years in duration.</p
- …