3,924 research outputs found
Supersymmetry Searches in GUT Models with Non-Universal Scalar Masses
We study SO(10), SU(5) and flipped SU(5) GUT models with non-universal soft
supersymmetry-breaking scalar masses, exploring how they are constrained by LHC
supersymmetry searches and cold dark matter experiments, and how they can be
probed and distinguished in future experiments. We find characteristic
differences between the various GUT scenarios, particularly in the
coannihilation region, which is very sensitive to changes of parameters. For
example, the flipped SU(5) GUT predict the possibility of
coannihilation, which is absent in the regions of the SO(10) and SU(5) GUT
parameter spaces that we study. We use the relic density predictions in
different models to determine upper bounds for the neutralino masses, and we
find large differences between different GUT models in the sparticle spectra
for the same LSP mass, leading to direct connections of distinctive possible
experimental measurements with the structure of the GUT group. We find that
future LHC searches for generic missing , charginos and stops will be able
to constrain the different GUT models in complementary ways, as will the Xenon
1 ton and Darwin dark matter scattering experiments and future FERMI or CTA
-ray searches.Comment: 21 pages, 10 Figures. V3: some comments and 1 reference added,
published version. JCAP03(2016)04
The double-Kerr equilibrium configurations involving one extreme object
We demonstrate the existence of equilibrium states in the limiting cases of
the double-Kerr solution when one of the constituents is an extreme object. In
the `extreme-subextreme' case the negative mass of one of the constituents is
required for the balance, whereas in the `extreme-superextreme' equilibrium
configurations both Kerr particles may have positive masses. We also show that
the well-known relation |J|=M^2 between the mass and angular momentum in the
extreme single Kerr solution ceases to be a characteristic property of the
extreme Kerr particle in a binary system.Comment: 12 pages, 3 figures, submitted to Class. Quantum Gra
Evidence of ongoing radial migration in NGC 6754: Azimuthal variations of the gas properties
Understanding the nature of spiral structure in disk galaxies is one of the
main, and still unsolved questions in galactic astronomy. However, theoretical
works are proposing new testable predictions whose detection is becoming
feasible with recent development in instrumentation. In particular, streaming
motions along spiral arms are expected to induce azimuthal variations in the
chemical composition of a galaxy at a given galactic radius. In this letter we
analyse the gas content in NGC 6754 with VLT/MUSE data to characterise its 2D
chemical composition and H line-of-sight velocity distribution. We find
that the trailing (leading) edge of the NGC 6754 spiral arms show signatures of
tangentially-slower, radially-outward (tangentially-faster, radially-inward)
streaming motions of metal-rich (poor) gas over a large range of radii. These
results show direct evidence of gas radial migration for the first time. We
compare our results with the gas behaviour in a -body disk simulation
showing spiral morphological features rotating with a similar speed as the gas
at every radius, in good agreement with the observed trend. This indicates that
the spiral arm features in NGC 6754 may be transient and rotate similarly as
the gas does at a large range of radii.Comment: 8 pages, 4 figures, accepted for publication in ApJL 2016 September
2
Surgical treatment of congenital pseudoarthrosis of the clavicle: Our 22-year, single-center experience
Objectives: This study reports the surgical outcomes in a patient cohort with congenital pseudarthrosis of the clavicle (CPC).
Patients and methods: A total of nine pediatric patients (5 males, 4 females; mean age: 4.43 years; range, 2 to 12 years) who were diagnosed with CPC and treated surgically with a minimum one-year follow-up between January 1996 and December 2018 were retrospectively analyzed. The patients were divided into two groups according to the fixation method as the Kirschner wire (K-wire; Group A, n=2) or stabilization with a plate (Group B, n=7). The physical function and symptoms were evaluated using the Quick Disabilities of the Arm, Shoulder and Hand (QuickDASH) scale.
Results: The mean age at the time of diagnosis was 2.95 (range, 0 to 12) years. Six cases were atrophic pseudarthrosis and three cases were hypertrophic. Radiographic consolidation occurred in all cases with a mean duration of 103.8±39.1 days, indicating no significant difference between the groups (p>0.05). Complications registered were a K-wire breakage in a patient in Group A and an internal fixation plate loosening in a patient in Group B. The mean postoperative follow-up was 2.98±1.82 years. The QuickDASH score was 0 points in all patients.
Conclusion: The early surgical indication based on refreshment of the pseudarthrosis focus, with bone autograft interposition when a failure exists to restore adequate clavicular length, and fixation are reliable alternatives with favorable clinical and radiological results in the mid- and long-term with fewer complications
Gaseous time projection chambers for rare event detection: Results from the T-REX project. II. Dark matter
As part of the T-REX project, a number of R&D and prototyping activities have
been carried out during the last years to explore the applicability of
Micromegas-read gaseous TPCs in rare event searches like double beta decay
(DBD), axion research and low-mass WIMP searches. While in the companion paper
we focus on DBD, in this paper we focus on the results regarding the search for
dark matter candidates, both axions and WIMPs. Small ultra-low background
Micromegas detectors are used to image the x-ray signal expected in axion
helioscopes like CAST at CERN. Background levels as low as
c keVcms have already been achieved in CAST while values
down to c keVcms have been obtained in a
test bench placed underground in the Laboratorio Subterr\'aneo de Canfranc.
Prospects to consolidate and further reduce these values down to
c keVcmswill be described. Such detectors, placed at the
focal point of x-ray telescopes in the future IAXO experiment, would allow for
10 better signal-to-noise ratio than CAST, and search for solar axions with
down to few 10 GeV, well into unexplored axion
parameter space. In addition, a scaled-up version of these TPCs, properly
shielded and placed underground, can be competitive in the search for low-mass
WIMPs. The TREX-DM prototype, with 0.300 kg of Ar at 10 bar, or
alternatively 0.160 kg of Ne at 10 bar, and energy threshold well below 1
keV, has been built to test this concept. We will describe the main technical
solutions developed, as well as the results from the commissioning phase on
surface. The anticipated sensitivity of this technique might reach
cm for low mass ( GeV) WIMPs, well beyond current
experimental limits in this mass range.Comment: Published in JCAP. New version with erratum incorporated (new figure
14
Origin of slow magnetic relaxation in Kramers ions with non-uniaxial anisotropy
Transition metal ions with long-lived spin states represent minimum size magnetic bits. Magnetic memory has often been associated with the combination of high spin and strong uniaxial magnetic anisotropy. Yet, slow magnetic relaxation has also been observed in some Kramers ions with dominant easy-plane magnetic anisotropy, albeit only under an external magnetic field. Here we study the spin dynamics of cobalt(II) ions in a model molecular complex. We show, by means of quantitative first-principles calculations, that the slow relaxation in this and other similar systems is a general consequence of time-reversal symmetry that hinders direct spin–phonon processes regardless of the sign of the magnetic anisotropy. Its magnetic field dependence is a subtle manifestation of electronuclear spin entanglement, which opens relaxation channels that would otherwise be forbidden but, at the same time, masks the relaxation phenomenon at zero field. These results provide a promising strategy to synthesize atom-size magnetic memories
Secondary use of data extracted from a clinical information system to assess the adherence of tidal volume and its impact on outcomes.
Objectives
To extract data from clinical information systems to automatically calculate high-resolution quality indicators to assess adherence to recommendations for low tidal volume.
Design
We devised two indicators: the percentage of time under mechanical ventilation with excessive tidal volume (>8 mL/kg predicted body weight) and the percentage of patients who received appropriate tidal volume (≤8 mL/kg PBW) at least 80% of the time under mechanical ventilation. We developed an algorithm to automatically calculate these indicators from clinical information system data and analyzed associations between them and patients’ characteristics and outcomes.
Settings
This study has been carried out in our 30-bed polyvalent intensive care unit between January 1, 2014 and November 30, 2019.
Patients
All patients admitted to intensive care unit ventilated >72 h were included.
Intervention
Use data collected automatically from the clinical information systems to assess adherence to tidal volume recommendations and its outcomes.
Main variables of interest
Mechanical ventilation days, ICU length of stay and mortality.
Results
Of all admitted patients, 340 met the inclusion criteria. Median percentage of time under mechanical ventilation with excessive tidal volume was 70% (23%–93%); only 22.3% of patients received appropriate tidal volume at least 80% of the time. Receiving appropriate tidal volume was associated with shorter duration of mechanical ventilation and intensive care unit stay. Patients receiving appropriate tidal volume were mostly male, younger, taller, and less severely ill. Adjusted intensive care unit mortality did not differ according to percentage of time with excessive tidal volume or to receiving appropriate tidal volume at least 80% of the time.
Conclusions
Automatic calculation of process-of-care indicators from clinical information systems high-resolution data can provide an accurate and continuous measure of adherence to recommendations. Adherence to tidal volume recommendations was associated with shorter duration of mechanical ventilation and intensive care unit stay.pre-print1126 K
- …