890 research outputs found
Mock Catalogs for UHECR Studies
We provide realistic mock-catalogs of cosmic rays above 40 EeV, for a pure
proton composition, assuming their sources are a random subset of ordinary
galaxies in a simulated, volume-limited survey, for various choices of source
density: 10^-3.5 Mpc^-3, 10^-4.0 Mpc^-3 and 10^-4.5 Mpc^-3. The spectrum at the
source is taken to be E^-2.3 and the effects of cosmological redshifting as
well as photo-pion and e^+ e^- energy losses are included.Comment: 7 pages, 4 figure
Principal eigenvalues and an anti-maximum principle for homogeneous fully nonlinear elliptic equations
We study the fully nonlinear elliptic equation in a
smooth bounded domain , under the assumption the nonlinearity is
uniformly elliptic and positively homogeneous. Recently, it has been shown that
such operators have two principal "half" eigenvalues, and that the
corresponding Dirichlet problem possesses solutions, if both of the principal
eigenvalues are positive. In this paper, we prove the existence of solutions of
the Dirichlet problem if both principal eigenvalues are negative, provided the
"second" eigenvalue is positive, and generalize the anti-maximum principle of
Cl\'{e}ment and Peletier to homogeneous, fully nonlinear operators.Comment: 32 page
Cost-utility of transcatheter aortic valve implantation for inoperable patients with severe aortic stenosis treated by medical management: a UK cost-utility analysis based on patient-level data from the ADVANCE study.
OBJECTIVE: To use patient-level data from the ADVANCE study to evaluate the cost-effectiveness of transcatheter aortic valve implantation (TAVI) compared to medical management (MM) in patients with severe aortic stenosis from the perspective of the UK NHS.
METHODS: A published decision-analytic model was adapted to include information on TAVI from the ADVANCE study. Patient-level data informed the choice as well as the form of mathematical functions that were used to model all-cause mortality, health-related quality of life and hospitalisations. TAVI-related resource use protocols were based on the ADVANCE study. MM was modelled on publicly available information from the PARTNER-B study. The outcome measures were incremental cost-effectiveness ratios (ICERs) estimated at a range of time horizons with benefits expressed as quality-adjusted life-years (QALY). Extensive sensitivity/subgroup analyses were undertaken to explore the impact of uncertainty in key clinical areas.
RESULTS: Using a 5-year time horizon, the ICER for the comparison of all ADVANCE to all PARTNER-B patients was £13 943 per QALY gained. For the subset of ADVANCE patients classified as high risk (Logistic EuroSCORE >20%) the ICER was £17 718 per QALY gained). The ICER was below £30 000 per QALY gained in all sensitivity analyses relating to choice of MM data source and alternative modelling approaches for key parameters. When the time horizon was extended to 10 years, all ICERs generated in all analyses were below £20 000 per QALY gained.
CONCLUSION: TAVI is highly likely to be a cost-effective treatment for patients with severe aortic stenosis
Electronic neuron within a ganglion of a leech (Hirudo medicinalis)
Fil:Aliaga, J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Busca, N. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Salles, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Experimental evaluation of environmental effects on a polymer-coated aluminium structure: a time-series analysis and pattern recognition approach
Temperature variation is an important issue that needs to be considered when trying to develop a reliable
Structural Health Monitoring (SHM) strategy. In the case that a data-based approach is chosen for damage
detection, environmental fluctuations could be erroneously regarded as an abnormal condition of the
structure and could mask the presence of damage. One of the objectives of the current work is to examine
a statistical pattern recognition approach for novelty detection under different temperature conditions. A
second important issue that could hinder the reliability of a SHM strategy is any kind of nonlinear
behaviour, not associated with damage, in a system. For the purposes of this paper, the dynamic behaviour
of a polymer-coated aluminium structure with ribs fixed with bolts is examined. The autoregressive
parameters are the damage sensitive features and later, it is performed Principal Component Analysis
(PCA) for robust novelty detection that takes into account the temperature variation
Observing muon decays in water Cherenkov detectors at the Pierre Auger Observatory
Muons decaying in the water volume of a Cherenkov detector of the Pierre
Auger Observatory provide a useful calibration point at low energy. Using the
digitized waveform continuously recorded by the electronics of each tank, we
have devised a simple method to extract the charge spectrum of the Michel
electrons, whose typical signal is about 1/8 of a crossing vertical muon. This
procedure, moreover, allows continuous monitoring of the detector operation and
of its water level. We have checked the procedure with high statistics on a
test tank at the Observatory base and applied with success on the whole array.Comment: 4 pages, 2 figures, proceedings of the 29th ICRC Pune, Indi
Kaolinite-based zeolites synthesis and their application in CO2 capture processes
In light of the urgent need of reducing the atmospheric CO2 emissions, the use of low-cost adsorbents, that exhibit a high affinity and CO2 adsorption capacity, is a promising method from the economic and environmental point of view to separate CO2 from the flue gas emitted from large sources of emissions like power-fueled plants. Clay minerals are low-cost raw materials with high availability all over planet and great versatility in the fields of adsorption and catalysis processes. The present study pretends to elucidate the link between the reaction conditions during the synthesis of the zeolite from kaolinite and its CO2 adsorption capacity. For that purpose, the type A zeolite was synthesized via hydrothermal process in alkaline solution using metakaolinite as a starting material. The metakaolinite was obtained by calcination of kaolinite at 600 degrees C and some parameters such as temperature and synthesis time were modified to optimize the synthesis aiming for a high CO2 adsorption capacity adsorbent. Synthesized materials were characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), N-2 adsorption-desorption at -196 degrees C and CO2 adsorption at 0 degrees C (up to 10 bars) isotherms and Nuclear Magnetic Resonance of solids (NMR). In addition, the adsorption capacity of CO2 was evaluated by means of CO2 adsorption-desorption isotherms at 25 degrees C up to atmospheric pressure. The obtained results indicated that synthesized zeolite 4A can be successfully prepared from natural kaolinite (via metakaolinization) at 100 degrees C for 48 h under alkaline conditions, showing chemical and physical properties similar to that of the commercial 4A zeolite
TeV Particle Astrophysics II: Summary comments
A unifying theme of this conference was the use of different approaches to
understand astrophysical sources of energetic particles in the TeV range and
above. In this summary I review how gamma-ray astronomy, neutrino astronomy and
(to some extent) gravitational wave astronomy provide complementary avenues to
understanding the origin and role of high-energy particles in energetic
astrophysical sources.Comment: 6 pages, 4 figures; Conference summary talk for "TeV Particle
Astrophysics II" at University of Wisconsin, Madison, 28-31 August 200
- …