190 research outputs found
A hybrid ANN-GA model to prediction of bivariate binary responses: Application to joint prediction of occurrence of heart block and death in patients with myocardial infarction
Background: In medical studies, when the joint prediction about occurrence of two events should be anticipated, a statistical bivariate model is used. Due to the limitations of usual statistical models, other methods such as Artificial Neural Network (ANN) and hybrid models could be used. In this paper, we propose a hybrid Artificial Neural Network-Genetic Algorithm (ANN-GA) model to prediction the occurrence of heart block and death in myocardial infarction (MI) patients simultaneously. Methods: For fitting and comparing the models, 263 new patients with definite diagnosis of MI hospitalized in Cardiology Ward of Hajar Hospital, Shahrekord, Iran, from March, 2014 to March, 2016 were enrolled. Occurrence of heart block and death were employed as bivariate binary outcomes. Bivariate Logistic Regression (BLR), ANN and hybrid ANN-GA models were fitted to data. Prediction accuracy was used to compare the models. The codes were written in Matlab 2013a and Zelig package in R3.2.2. Results: The prediction accuracy of BLR, ANN and hybrid ANN-GA models was obtained 77.7%, 83.69% and 93.85% for the training and 78.48%, 84.81% and 96.2% for the test data, respectively. In both training and test data set, hybrid ANN-GA model had better accuracy. Conclusions: ANN model could be a suitable alternative for modeling and predicting bivariate binary responses when the presuppositions of statistical models are not met in actual data. In addition, using optimization methods, such as hybrid ANN-GA model, could improve precision of ANN model. © 2016, Health Hamadan University of Medical Sciences. All rights reserved
High repetition rate and coherent Free-Electron Laser in the tender X-rays based on the Echo-Enabled Harmonic Generation of an Ultra-Violet Oscillator pulse
Fine time-resolved analysis of matter - i.e. spectroscopy and photon
scattering - in the linear response regime requires a fs-scale pulsed, high
repetition rate, fully coherent X-ray source. A seeded Free-Electron Laser
(FEL) driven by a Super-Conducting Linac, generating -
coherent photons at 2-5 keV with abou 0.5 MHz of repetition rate, can address
this need. The seeding scheme proposed is the Echo-Enabled Harmonic Generation,
alimented by a FEL Oscillator working at 13.6 nm with a cavity based on Mo-Si
mirrors. The whole chain of the X-ray generation is here described by means of
start-to-end simulations. Comparisons with the Self Amplified Spontaneus
Emission and a fresh-bunch harmonic cascade performed with similar electron
beams show the validity of this scheme
Toxicity and sublethal effects of phthalides analogs to Rhyzopertha dominica
Phthalides and their precursors have demonstrated a large variety of biological activities. Eighteen phthalides were synthesized and tested on the stored grain pest Rhyzopertha dominica. In the screening bioassay, compounds rac‐(2R,2aS,4R,4aS,6aR,6bS,7R)‐7‐bromohexahydro‐2,4‐methano‐1,6‐dioxacyclopenta[cd]pentalen‐5(2H)‐one (15) and rac‐(3R,3aR,4R,7S,7aS)‐3‐(propan‐2‐yloxy)hexahydro‐4,7‐methano‐2‐benzofuran‐1(3H)‐one (17) showed mortality similar to the commercial insecticide, Bifenthrin® (≥90 %). The time (LT50) and dose (LD50) necessary to kill 50 % of the R. dominica population were determined for the most efficacious phthalides 15 and 17. Compound 15 presented the lowest LD50 (1.97 μg g−1), being four times more toxic than Bifenthrin® (LD50=9.11 μg g−1). Both compounds presented an LT50 value equal to 24 h. When applied at a sublethal dose, both phthalides (especially compound 15), reduced the emergence of the first progeny of R. dominica. These findings highlight the potential of phthalides 15 and 17 as precursors for the development of insecticides for R. dominica control
Single-shot transverse coherence in seeded and unseeded free-electron lasers: A comparison
The advent of x-ray free-electron lasers (FELs) drastically enhanced the capabilities of several analytical techniques, for which the degree of transverse (spatial) coherence of the source is essential. FELs can be operated in self-amplified spontaneous emission (SASE) or seeded configurations, which rely on a qualitatively different initialization of the amplification process leading to light emission. The degree of transverse coherence of SASE and seeded FELs has been characterized in the past, both experimentally and theoretically. However, a direct experimental comparison between the two regimes in similar operating conditions is missing, as well as an accurate study of the sensitivity of transverse coherence to key working parameters. In this paper, we carry out such a comparison, focusing in particular on the evolution of coherence during the light amplification process
Dynamics of Higher Spin Fields and Tensorial Space
The structure and the dynamics of massless higher spin fields in various
dimensions are reviewed with an emphasis on conformally invariant higher spin
fields. We show that in D=3,4,6 and 10 dimensional space-time the conformal
higher spin fields constitute the quantum spectrum of a twistor-like particle
propagating in tensorial spaces of corresponding dimensions. We give a detailed
analysis of the field equations of the model and establish their relation with
known formulations of free higher spin field theory.Comment: JHEP3 style, 40 pages; v2 typos corrected, comments and references
added; v3 published versio
MÉTODOS PARA CONSERVAÇÃO A LONGO PRAZO DE SEMENTES DE TABEBUIA SPP - BIGNONIACEAE
O objetivo deste trabalho foi determinar a viabilidade de sementes de Tabebuía ímpetígínosa, Tabebuía ochreceee e Tabebuía avellanedae, após secagem e/ou armazenamento sob temperatura subzero, visando à conservação de seu germoplasma a longo prazo. As sementes foram submetidas aos seguintes tratamentos: secagem; secagem e armazenamento a -20°C; e armazenamento a -20°C. Os tratamentos foram aplicados por períodos de 0 a 7 dias, com intervalos de 1 dia entre os períodos. Para avaliar a qualidade das sementes após os tratamentos, foram conduzidos testes de germinação e de grau de umidade. Os resultados obtidos mostraram que as sementes destas espécies foram tolerantes à secagem e ao armazenamento a -20°C, indicando a possibilidade de serem conservadas a longo prazo em bancos de germoplasma
Characterization of soft x-ray echo-enabled harmonic generation free-electron laser pulses in the presence of incoherent electron beam energy modulations
Echo-enabled harmonic generation free-electron lasers (EEHG FELs) are promising candidates to produce fully coherent soft x-ray pulses by virtue of efficient high-harmonic frequency up-conversion from ultraviolet lasers. The ultimate spectral limit of EEHG, however, remains unclear, because of the broadening and distortions induced in the output spectrum by residual broadband energy modulations in the electron beam. We present a mathematical description of the impact of incoherent (broadband) energy modulations on the bunching spectrum produced by the microbunching instability through both the accelerator and the EEHG line. The model is in agreement with a systematic experimental characterization of the FERMI EEHG FEL in the photon energy range 130\u2013210 eV. We find that amplification of electron beam energy distortions primarily in the EEHG dispersive sections explains an observed reduction of the FEL spectral brightness proportional to the EEHG harmonic number. Local maxima of the FEL spectral brightness and of the spectral stability are found for a suitable balance of the dispersive sections\u2019 strength and the first seed laser pulse energy. Such characterization provides a benchmark for user experiments and future EEHG implementations designed to reach shorter wavelengths
Gauge Invariant Lagrangians for Free and Interacting Higher Spin Fields. A Review of the BRST formulation
We give a detailed review of the construction of gauge invariant Lagrangians
for free and interacting higher spin fields using the BRST approach developed
over the past few years.Comment: Extended version of the contribution to the volume dedicated to the
60th birthday of Prof I.L. Buchbinder; 58 pages. v2 References added, some
typos fixed, a couple of clarifications added. v3 To appear in International
journal of Modern Physics A (pubished version), some typos fixed, references
adde
- …