525 research outputs found
Calidad de los diagnósticos en urgencias de las lesiones por causas externas que requieren ingreso hospitalario
SummaryObjectiveTo establish the quality of emergency department diagnoses for those patients whose injuries required hospital admission.MethodsEmergency and hospital discharge diagnostics were retrieved for 339 injured patients. Severity scores (ISS) were calculated using an automatic conversion procedure (ICDMAP). Emergency diagnoses for each patient (grouped into categories) were compared with the hospital discharge ones. Quality was analyzed based on accuracy (Percy groups) and reliability (percentage of concordance) measurements. Severity scores were evaluated using reliability measures (percentage of concordance and intraclass correlation coefficient -ICC-).ResultsMean diagnoses per patient were 1.1 at the emergency department and 1.4 at hospital discharge. In the latter, there were diagnoses in each category except for those more unspecific, where there was a reduction. Overall,emergency information showed under notification. Severity scores were higher with hospital discharge data. There was a 63% percentage of concordance. When grouped into categories, severity scores had an ICC of 0.61 (moderate-good).ConclusionEmergency departments are a potential good source of information about injury severity even for those patients who require hospital admission. Emergency department injury surveillance can be very useful in assessing the magnitude and distribution of injury severity at the population level. Nevertheless for individual severity assessment, use of hospital discharge information is recommended
On F-theory Quiver Models and Kac-Moody Algebras
We discuss quiver gauge models with bi-fundamental and fundamental matter
obtained from F-theory compactified on ALE spaces over a four dimensional base
space. We focus on the base geometry which consists of intersecting F0=CP1xCP1
Hirzebruch complex surfaces arranged as Dynkin graphs classified by three kinds
of Kac-Moody (KM) algebras: ordinary, i.e finite dimensional, affine and
indefinite, in particular hyperbolic. We interpret the equations defining these
three classes of generalized Lie algebras as the anomaly cancelation condition
of the corresponding N =1 F-theory quivers in four dimensions. We analyze in
some detail hyperbolic geometries obtained from the affine A base geometry by
adding a node, and we find that it can be used to incorporate fundamental
fields to a product of SU-type gauge groups and fields.Comment: 13 pages; new equations added in section 3, one reference added and
typos correcte
On Brane Inflation Potentials and Black Hole Attractors
We propose a new potential in brane inflation theory, which is given by the
arctangent of the square of the scalar field. Then we perform an explicit
computation for inflationary quantities. This potential has many nice features.
In the small field approximation, it reproduces the chaotic and MSSM
potentials. It allows one, in the large field approximation, to implement the
attractor mechanism for bulk black holes where the geometry on the brane is de
Sitter. In particular, we show, up to some assumptions, that the Friedman
equation can be reinterpreted as a Schwarzschild black hole attractor equation
for its mass parameter.Comment: 12 pages. Reference updated and minor changes added. Version to
appear in Int. J. Mod. Phys.
Motion and Trajectories of Particles Around Three-Dimensional Black Holes
The motion of relativistic particles around three dimensional black holes
following the Hamilton-Jacobi formalism is studied. It follows that the
Hamilton-Jacobi equation can be separated and reduced to quadratures in analogy
with the four dimensional case. It is shown that: a) particles are trapped by
the black hole independently of their energy and angular momentum, b) matter
alway falls to the centre of the black hole and cannot understake a motion with
stables orbits as in four dimensions. For the extreme values of the angular
momentum of the black hole, we were able to find exact solutions of the
equations of motion and trajectories of a test particle.Comment: Plain TeX, 9pp, IPNO-TH 93/06, DFTUZ 93/0
Embedding Fractional Quantum Hall Solitons in M-theory Compactifications
We engineer U(1)^n Chern-Simons type theories describing fractional quantum
Hall solitons (QHS) in 1+2 dimensions from M-theory compactified on eight
dimensional hyper-K\"{a}hler manifolds as target space of N=4 sigma model.
Based on M-theory/Type IIA duality, the systems can be modeled by considering
D6-branes wrapping intersecting Hirzebruch surfaces F_0's arranged as ADE
Dynkin Diagrams and interacting with higher dimensional R-R gauge fields. In
the case of finite Dynkin quivers, we recover well known values of the filling
factor observed experimentally including Laughlin, Haldane and Jain series.Comment: Latex, 14 pages. Modified version, to appear in IJGMM
On Hexagonal Structures in Higher Dimensional Theories
We analyze the geometrical background under which many Lie groups relevant to
particle physics are endowed with a (possibly multiple) hexagonal structure.
There are several groups appearing, either as special holonomy groups on the
compactification process from higher dimensions, or as dynamical string gauge
groups; this includes groups like SU(2),SU(3), G_2, Spin(7), SO(8) as well as
E_8 and SO(32). We emphasize also the relation of these hexagonal structures
with the octonion division algebra, as we expect as well eventually some role
for octonions in the interpretation of symmetries in High Energy Physics.Comment: 9 pages, Latex, 3 figures. Accepted for publication in International
Journal of Theoretical Physic
A technical evaluation, performance analysis and risk assessment of multiple novel oxy-turbine power cycles with complete CO2 capture
In recent years there has been growing concern about greenhouse gas emissions (particularly CO2 emissions) and global warming. Oxyfuel combustion is one of the key technologies for tackling CO2 emissions in the power industry and reducing their contribution to global warming. The technology involves burning fuel with high-purity oxygen to generate mainly CO2 and steam, enabling easy CO2 separation from the flue gases by steam condensation. In fact, 100% CO2 capture and near-zero NOx emissions can be achieved with this technology.
This study examines nineteen different oxy-turbine cycles, identifying the main parameters regarding their operation and development. It also analyses the use of advanced natural gas (NG) combustion cycles from the point of view of the carbon capture and storage (CCS) and considering political, legislative and social aspects of deploying this technology. Six oxy-turbine cycles which are at the most advanced stages of development (NetPower, Clean Energy Systems CES), Modified Graz, E-MATIANT, Advanced Zero Emission Power AZEP 100% and Semi-Closed Oxy-fuel Combustion Combined Cycle (SCOC-CC)), were chosen to conduct a Political, Environmental, Social, Technological, Legislative and Economic (PESTLE) risk analysis. This compares each technology with a conventional combined cycle gas turbine (CCGT) power plant without carbon capture as the base-case scenario. Overall, the net efficiency of the different oxy-turbine cycles ranges between 43.6% and 65%, comparable to a CCGT power plant, while providing the extra benefits of CO2 capture and lower emissions.
A multi-criteria analysis carried out using DECERNS (Decision Evaluation in Complex Risk Network Systems) software determined that, depending on the specific criterion considered, one can draw different conclusions. However, in terms of technology, environment and social opinion, the most promising cycles are the NetPower and CES cycles, whereas from an economic point of view, E-MATIANT is more competitive in the energy market. Giving each factor equal importance, the NetPower cycle must be considered to be the best oxy-turbine cycle based on our analysis.
Most of the oxy-turbine cycles are still under development and only a few cycles (e.g., CES and NetPower) are progressing to the demonstration phase. In consequence, political measures such as CO2 tax and emission allowances need to be implemented for oxy-turbine technologies to become the preferred option for fossil fuel power plants burning natural gas
- …