Probing singularities in quantum cosmology with curvature scalars

We provide further evidence that the canonical quantization of cosmological models eliminates the classical Big Bang singularity, using the {\it DeBroglie-Bohm} interpretation of quantum mechanics. The usual criterion for absence of the Big Bang singularity in Friedmann-Robertson-Walker quantum cosmological models is the non-vanishing of the expectation value of the scale factor. We compute the `local expectation value' of the Ricci and Kretschmann scalars, for some quantum FRW models. We show that they are finite for all time. Since these scalars are elements of general scalar polynomials in the metric and the Riemann tensor, this result indicates that, for the quantum models treated here, the `local expectation value' of these general scalar polynomials should be finite everywhere. Therefore, we have further evidence that the quantization of the models treated here eliminates the classical Big Bang singularity. PACS: 04.40.Nr, 04.60.Ds, 98.80.Qc.Comment: 9 pages, 6 figure

A Combination Of The -α3.7 And -medii Alleles Causing Hemoglobin H Disease In A Brazilian Patient

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)39180832014/00984-3, FAPESP, Fundação de Amparo à Pesquisa do Estado de São PauloFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Explorando sistemas hamiltonianos II: pontos de equilíbrio degenerados

Neste segundo artigo sobre sistemas hamiltonianos, apresentamos o método da explosão (blow-up) para a determinação da natureza de pontos fixos (pontos de equilíbrio) degenerados. Aplicamos o método a dois modelos hamiltonianos com um e dois graus de liberdade, respectivamente. Primeiramente, analisamos um sistema formado por um pêndulo simples submetido a um torque externo constante. Em seguida, consideramos um sistema formado por um pêndulo duplo com segmentos de comprimentos e massas iguais, também submetidos a torques externos constantes e não nulos. A presença de pontos de equilíbrio degenerados nos casos dos pêndulos simples e duplo ocorre para certos valores dos torques externos

The Heumann-Hotzel model for aging revisited

Since its proposition in 1995, the Heumann-Hotzel model has remained as an obscure model of biological aging. The main arguments used against it were its apparent inability to describe populations with many age intervals and its failure to prevent a population extinction when only deleterious mutations are present. We find that with a simple and minor change in the model these difficulties can be surmounted. Our numerical simulations show a plethora of interesting features: the catastrophic senescence, the Gompertz law and that postponing the reproduction increases the survival probability, as has already been experimentally confirmed for the Drosophila fly.Comment: 11 pages, 5 figures, to be published in Phys. Rev.

Modelling of Optical Detection of Spin-Polarized Carrier Injection into Light-Emitting Devices

We investigate the emission of multimodal polarized light from Light Emitting Devices due to spin-aligned carriers injection. The results are derived through operator Langevin equations, which include thermal and carrier-injection fluctuations, as well as non-radiative recombination and electronic g-factor temperature dependence. We study the dynamics of the optoelectronic processes and show how the temperature-dependent g-factor and magnetic field affect the polarization degree of the emitted light. In addition, at high temperatures, thermal fluctuation reduces the efficiency of the optoelectronic detection method for measuring spin-polarization degree of carrier injection into non-magnetic semicondutors.Comment: 15 pages, 7 figures, replaced by revised version. To appear in Phys. Rev.

Evaluation Of Pspl Plate Erasing Time Of A Digital Dental Radiology System

Denoptix (CEDH Gendex Dental System, Milan, Italy) dental imaging system uses photo-stimulable phosphor luminescence (PSPL) plates to store energy during X-ray exposure, being later processed by a laser reader and digitizer. Afterwards the plate is erased and re-used. The cleaning process described by the manufacturer consists of exposing the PSPL plates to negatoscope light for 5 minutes. Proper light intensity and exact erasing time must be considered in order to guarantee good quality procedures in its re-utilization. X-ray exposed plates were submitted to four negatoscopes with different measured light intensities for several periods of light exposure, until the Denoptix system was unable to process the latent image in the plates, and we considered then that the plates were cleaned. We have found the relationships between erasing time, exposed dose and negatoscope light intensity. We have also measured the relative plate image fading with negatoscope light exposure time. We have concluded that a Poisson process governs plate erasing. Considering clinical situations, we have shown that it was possible to largely reduce erasing time and increase plate re-utilization. The exponential decay of image data also suggested a still smaller erasing time, representative of a partial cleaning status assuming that residual noise presence in the erased plate is clinically acceptable.4320227235Janhom, A., Effect of noise on the compressibility and diagnostic accuracy for caries detection of digital bitewing radiographs (1999) Dentomaxillofacial Radiology, 28, pp. 6-12Huda, W., Comparison of a photo-stimulable phosphor system with film for dental radiology (1997) Oral Surgery Oral Medicine Oral Pathology, 84, pp. 725-731Brettle, D.S., The imaging performance of a storage phosphor system for dental radiography (1996) The British Journal of Radiology, 69, pp. 256-261Yoshiura, K., Physical evaluation of a system for direct digital intra-oral radiography based on a charged-coupled device (1999) Dentomaxillofacial Radiology, 28, pp. 277-283Xinhua, A novel algorithm for measuring the MTF of a digital radiographic system with a CCD array detector (2000) SPIE, 3977, pp. 580-587Hildebold, C.F., Dental photostimulable phosphor radiology (2000) Dental Clinics of North America, 44 (2), pp. 273-297(1998) Denoptix System User Manual, , CEDH Gendex Dental System, Milan, ItalyBethea, R.M., Duran, B.S., Benllion, T.L., (1995) Statistical Methods for Engineers and Scientists, , Mc Hill Reckker, New York, NYWebb, S., (1995) The Physics of Medical Imaging, , Institute of Physis Publishing, Bristol, UK(1996) Mathematics and Physics of Emerging Biomedical Imaging, , National Research Council, Institute of Medicine, National Academy Press, Washington D.CBarret, H., Harrison, H., Swindell, W., (1981) Radiological Imaging: The Theory of Image Formation, Detection and Processing, 1-2. , Academic Press, London, UKDaint, J.C., Shaw, R., (1976) Image Science - Principles, Analyses and Evaluation of Photographic-Type Imaging Process, , Academic Press, London, U

Environment Influence On Pspl-based Digital Dental Radiology Systems

Photo-stimulable phosphor luminescence technology (PSPL) has been used in Digora (Soredex, Finland) and Denoptix (CEDH Gendex, Italy) digital dental radiology imaging systems. PSPL plates store X-ray energy during exposition, being later processed by a laser reader and digitizer. Afterward they are erased and re-used. The large band of energy absorption provides PSPL systems with an extensive dynamic scale but at the same time a high sensibility to the incoming noise of environmental radiations. We have measured environment influences (electromagnetic radiation) for Digora and Denoptix plates after X-ray exposure and before digital processing. We have first compared the processing of PSPL plates "in dark" against "in light" environments. In another experiment, the exposed plates were also processed after being positioned 10 cm away from a 17 inches video monitor screen and to its laterals for 5, 10, 15, 20, 25 and 30 minutes (plates protected against light). The acquired images were used to calculate the noise power spectra (NPS) in each case. We have noticed that there was an increase in the noise spectra energy of "in light" processing compared to "in dark" processing. There was also an increment in the NPS energy when the images were processed after the exposition of the plates to the radiation emanated from video monitor.4320219226Huda, W., Comparison of a photostimulable phosphor system with film for dental radiology (1997) Oral Surgery Oral Medicine Oral Pathology, 84, pp. 725-731Brettle, D.S., The imaging performance of a storage phosphor system for dental radiography (1996) The British Journal of Radiology, 69, pp. 256-261Xinhua, A novel algorithm for measuring the MTF of a digital radiographic system with a CCD array detector (2000) SPIE, 3977, pp. 580-587Knüpfer, W., Novel X-ray detectors for medical imaging (1999) Nuclear Physics, 78, pp. 610-615Hildebold, C.F., Dental photostimulable phosphor radiology (2000) Dental Clinics of North America, 44 (2), pp. 273-297Stamatakis, Dose response of a storage phosphor system for intraoral radiography (1999) Dentomaxillofacial Radiology, 28, pp. 272-276Yoshiura, K., Physical evaluation of a system for direct digital intra-oral radiography based on a charged-coupled device (1999) Dentomaxillofacial Radiology, 28, pp. 277-283Workman, A., Brettle, D.S., Physical performance measures of radiographic imaging systems (1997) Dentomaxillofacial Radiology, 26, pp. 139-146Granfors, P.R., Performance characteristics of an amorphous silicon flat panel X-ray imaging detector (1999) SPIE, 3659, pp. 480-490Yoshiura, K., Physical evaluation of a system for direct digital intra-oral radiography based on a charged-coupled device (1999) Dentomaxillofacial Radiology, 28, pp. 277-283Kengyelics, S.M., Image quality evaluation of a direct digital radiology detector operating in a UK radiology department (1999) SPIE, 3659, pp. 24-35Granfords, P.R., Aufrichtig, P.R.R., DQE(f) of an amorphous silicon flat panel X-ray detector: Detector parameter influences and measurement methodology (2000) SPIE, 3977, pp. 2-13Dobbins III, J.T., DQE(f) of four generations of computed radiography devices (1995) Medical Physics, 22, pp. 1581-1593Cowen, A.R., Workman, A., A physical image quality evaluation of a digital spot flurography system (1992) Phys. Med. Biol., 37, pp. 325-342Daint, J.C., Shaw, R., (1976) Image Science - Principles, Analyses and Evaluation of Photographic-Type Imaging Process, , Academic Press, London, UKBethea, R.M., Duran, B.S., Benllion, T.L., (1995) Statistical Methods for Engineers and Scientists, , Mc Hill Reckker, New York, NYZanella, G., Zannoni, R., DQE of imaging detectors in terms of spatial frequency (1999) Nuclear Instruments and Methods Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 437, pp. 163-167Zanella, G., Zannoni, R., The role of the quantum efficiency on the DQE of an imaging detector (1996) Nuclear Instruments and Methods in Physics Research A, 381, pp. 157-160Costa, S., DQE measurement in a scintillating glass optical fiber detector for X-ray imaging (1996) Nuclear Instruments and Methods in Physics Research A, 380, pp. 568-571Meyer, R.R., Experimental characterization of CCD cameras for HREM at 300kV (2000) Ultramicroscopy, 85, pp. 9-13Onttonello, P., MTF and DQE measurement in imaging detectors by their single-event response (1998) Nuclear Instruments and Methods in Physics Research Section A, 419, pp. 731-735Kandarakis, I., An experimental method for the determination of spatial-frequency-dependent detective quantum efficiency (DQE) of scintillators used in X-ray imaging detectors (1997) Nuclear Instruments and Methods in Physics Research Section A, 399, pp. 335-34

On the energy growth of some periodically driven quantum systems with shrinking gaps in the spectrum

We consider quantum Hamiltonians of the form H(t)=H+V(t) where the spectrum of H is semibounded and discrete, and the eigenvalues behave as E_n~n^\alpha, with 0<\alpha<1. In particular, the gaps between successive eigenvalues decay as n^{\alpha-1}. V(t) is supposed to be periodic, bounded, continuously differentiable in the strong sense and such that the matrix entries with respect to the spectral decomposition of H obey the estimate |V(t)_{m,n}|0, p>=1 and \gamma=(1-\alpha)/2. We show that the energy diffusion exponent can be arbitrarily small provided p is sufficiently large and \epsilon is small enough. More precisely, for any initial condition \Psi\in Dom(H^{1/2}), the diffusion of energy is bounded from above as _\Psi(t)=O(t^\sigma) where \sigma=\alpha/(2\ceil{p-1}\gamma-1/2). As an application we consider the Hamiltonian H(t)=|p|^\alpha+\epsilon*v(\theta,t) on L^2(S^1,d\theta) which was discussed earlier in the literature by Howland

Bootstrapping a Portuguese WordNet from Galician, Spanish and English wordnets

Series: Lecture notes in computer science, ISSN 0302-9743, vol. 8854In this article we exploit the possibility on bootstrapping an European Portuguese WordNet from the English, Spanish and Galician wordnets using Probabilistic Translation Dictionaries automatically created from parallel corpora. The process generated a total of 56~770 synsets and 97~058 variants. An evaluation of the results using the Brazilian OpenWordNet-PT as a gold standard resulted on a precision varying from 53\% to 75\% percent, depending on the cut-line. The results were satisfying and comparable to similar experiments using the WN-Toolkit.PEst-OE/EEI/UI0752/2014, TIN2012-38584-C06-01, TIN2012-38584-C06-0