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Dopplervelocimetria do fluxo normal da valva tricúspide fetal entre 11 e 13 semanas e 6 dias de gestação; Normal fetal tricuspid valve dopplervelocimetry at 11 to 13 weeks and 6 days

Ninno, Milena Almeida Prado
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 14/04/2010 PT
Relevância na Pesquisa
25.57%
Objetivo: Determinar os valores dopplervelocimétricos normais do fluxo através da valva tricúspide em gestações únicas, entre 11 e 13 semanas e seis dias. Examinar a reprodutibilidade dos parâmetros avaliados e sua correlação com variáveis clínicas maternas e obstétricas. Métodos: Estudo prospectivo envolvendo 166 gestações únicas, com desfecho normal, examinadas entre 11 e 13 semanas e seis dias, no período de fevereiro de 2006 a agosto de 2008. Foram aferidas as velocidades máximas das ondas E e A, duração do ciclo cardíaco completo e sua fase diastólica e calculadas as relações onda E/onda A e diástole/ciclo. Os valores normais foram descritos pelas respectivas médias e desvio-padrão. Para análise da reprodutibilidade desses parâmetros foi calculado o coeficiente de correlação intra-classes em 12 casos examinados por dois examinadores. Regressão linear simples e multivariada foram empregadas para examinar a correlação dos parâmetros dopplervelocimétricos entre si e com a idade gestacional, a medida da translucência nucal e variáveis maternas. Resultados: Neste intervalo gestacional, os valores normais encontrados foram: onda E, 25 (± 4,6) cm/s; onda A, 42,9 (± 5,9) cm/s; relação E/A, 0,58 (± 0...

Sobrecargas retangulares em diferentes domínios de intensidade: respostas cardiorrespiratórias, metabólicas e da percepção subjetiva de esforço em instantes relativos ao tempo de exaustão; Constant workload exercises in different intensity domains: cardiorespiratory, metabolic and perceived exertion responses in different moments relative to the time to exhaustion

Pires, Flávio de Oliveira
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 11/02/2010 PT
Relevância na Pesquisa
25.47%
Introdução: Em particular, não se sabe se o exercício físico termina com falha da homeostase metabólica em intensidades pertencentes ao domínio moderado, pesado e severo. Este estudo examinou as respostas fisiológicas durante exercícios de sobrecargas constantes até a exaustão, executadas em diferentes domínios metabólicos. Métodos: Dez homens saudáveis executaram quarto cargas constantes as quais corresponderam aos domínios de intensidade moderada (LL1), pesada (LL50% e LL2) e severa (LW25%). Parâmetros metabólicos e cardiorrespiratórios e a percepção subjetiva de esforço (PSE) foram medidos em intervalos regulares de tempo. Resultados: O tempo de exaustão em cada carga constante foi: 93,8 (± 18,0), 77,0 (± 22,9), 44,5 (± 16,0) e 22,8 (± 10,6) minutos em LL1, LL50%, LL2 e LW25%, respectivamente. Quando os dados foram analisados em relação ao tempo absoluto de exercício, significantes variações temporais foram encontradas na razão de trocas respiratórias (RER) e nas concentrações plasmáticas de potássio em LL1; no VO2, VCO2, RER, freqüência respiratória (FR), concentrações plasmáticas de norepinefrina e potássio em LL50%; na RER e nas concentrações plasmáticas de norepinefrina...

Comparação de alguns parâmetros ecocardiográficos medidos a partir de cortes transversais e longitudinais em cães

Cardoso, Liliana de Jesus Casaca
Fonte: Universidade de Lisboa. Faculdade de Medicina Veterinária Publicador: Universidade de Lisboa. Faculdade de Medicina Veterinária
Tipo: Dissertação de Mestrado
Publicado em 13/01/2015 POR
Relevância na Pesquisa
25.55%
Dissertação de Mestrado Integrado em Medicina Veterinária; Contexto: Apesar da existência de técnicas mais avançadas, em Portugal, a ecocardiografia trans-torácica é hoje em dia a principal ferramenta dos médicos veterinários no diagnóstico e avaliação da evolução da doença cardíaca em cães e gatos. Uma ecocardiografia completa engloba, além de outras fases, a medição de três parâmetros, o EPSS (E point to septal separation), o rácio átrio esquerdo/aorta (AE/Ao) e a fração de encurtamento sistólica (FS), os quais em conjunto com a restante informação colhida permitem avaliar a função cardíaca e as lesões cardíacas, quando presentes, bem como as suas causas e consequências fisiopatológicas. Devido a dificuldades técnicas na realização dos cortes padrão surge muitas vezes a necessidade de optar por cortes ecocardiográficos alternativos. Objetivos: Este trabalho procura esclarecer o grau de equivalência da medição do EPSS, rácio AE/Ao e FS a partir de cortes transversais em comparação com cortes longitudinais do coração em cães Amostra Populacional: 121 cães, de ambos os sexos (56 fêmeas e 65 machos) e de idades compreendidas entre os 4 meses e os 18 anos de idade, sendo 65 deles de raça pura. Em termos clínicos...

Levofloxacin Population Pharmacokinetics and Creation of a Demographic Model for Prediction of Individual Drug Clearance in Patients with Serious Community-Acquired Infection

Preston, Sandra L.; Drusano, George L.; Berman, Adam L.; Fowler, Cynthia L.; Chow, Andrew T.; Dornseif, Bruce; Reichl, Veronica; Natarajan, Jaya; Wong, Frankie A.; Corrado, Michael
Fonte: American Society for Microbiology Publicador: American Society for Microbiology
Tipo: Artigo de Revista Científica
Publicado em /05/1998 EN
Relevância na Pesquisa
25.47%
Population pharmacokinetic modeling is a useful approach to obtaining estimates of both population and individual pharmacokinetic parameter values. The potential for relating pharmacokinetic parameters to pharmacodynamic outcome variables, such as efficacy and toxicity, exists. A logistic regression relationship between the probability of a successful clinical and microbiological outcome and the peak concentration-to-MIC ratio (and also the area under the plasma concentration-time curve [AUC]/MIC ratio) has previously been developed for levofloxacin; however, levofloxacin assays for determination of the concentration in plasma are not readily available. We attempted to derive and validate demographic variable models to allow prediction of the peak concentration in plasma and clearance (CL) from plasma for levofloxacin. Two hundred seventy-two patients received levofloxacin intravenously for the treatment of community-acquired infection of the respiratory tract, skin or soft tissue, or urinary tract, and concentrations in plasma, guided by optimal sampling theory, were obtained. Patient data were analyzed by the Non-Parametric Expectation Maximization approach. Maximum a posteriori probability Bayesian estimation was used to generate individual parameter values...

1-(5-Nitro-2-oxoindolin-3-ylidene)thiosemicarbazide

Bandeira, Katlen Crhistian Tribuzy; Bresolin, Leandro; Beck, Johannes; Daniels, Jorg; Oliveira, Adriano Bof de
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
65.4%
In the title molecule, C9H7N5O3S, there is an intramolecular N-H...O. The molecule is essentially planar, with the maximum deviation from the mean plane of the 18 non-H atoms being 0.135 (2) Å for the amine N atom. In the crystal, the molecules are connected via intermolecular N-H...O and N-H...S hydrogen bonds, forming two-dimensional networks lying parallel to (10overline4). They are separated by an interplanar distance of 3.3214 (9) Å, leading to [pi]-[pi] interactions which stabilize the crystal structure.

Die HLA-DR-Beladung von Monozyten bei Neu- und Frühgeborenen: Referenzwerte, Determinanten und diagnostische Wertigkeit bei der early-onset Infektion; HLA-DR on monocytes of neonates and premature infants: reference values, determinates and diagnostic validity in case of an early onset bacterial infection

Spreemann, Till
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
Relevância na Pesquisa
25.55%
Hintergrund: Eine neonatale bakterielle Infektion ist mit hohem Morbiditäts- und Mortalitätsrisiko behaftet. Bei septischen Erwachsenen gilt die HLA-DR-Rezeptordichte auf Monozyten als Maß der Immunkompetenz. Eine niedrige Beladung geht mit schlechterem sepsisisbedingtem outcome einher. Ziel: Evaluation der diagnostischen Wertigkeit von HLA-DR im Rahmen einer early-onset bacterial infection (EOBI). Hierzu wurden Referenzwerte für reife Neugeborene erstellt. Mit diesen wurde die Beladung bei an einer EOBI erkrankten Neugeborenen verglichen. Methodik: Nach elterlichem Einverständnis erfolgte die quantitative Bestimmung durchflusszytometrisch (FACScan, Becton-Dickinson) mit Hilfe des QuantiBRITE-Assays (Anti-HLA-DR PE/Anti-Monocyte PerCP-Cy5.5, Becton-Dickinson). Die longitudinale Vergleichbarkeit wurde durch die Mitführung eines internen Standards gewährleistet. In die Erstellung der Referenzwerte gingen 186 Messungen von 158 Neugeborenen (57,6 % männlich, Gestationsalter 280 (259 - 298) Tage, Geburtsgewicht 3.400 (2.050 - 5.350) Gramm) ein, bei welchen klinisch und serologisch eine EOBI ausgeschlossen wurde. 55 Messungen von 47 an einer EOBI erkrankten Reifgeborenen (63,8 % männlich, Gestationsalter 278 (262 – 293) Tage...

N' -[3-(Hydroxyimino)butan-2-ylidene]- 4-methylbenzene-1-sulfonohydrazide

Siqueira, Maria Carolina Bulhosa; Gervini, Vanessa Carratu; Oliveira, Leandro; Locatelli, Aline; Oliveira, Adriano Bof de
Fonte: Universidade Federal do Rio Grande Publicador: Universidade Federal do Rio Grande
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
55.42%
In the title compound, C11H15N3O3S, the C-S-N(H)-N linkage is nonplanar, the torsion angle being 75.70 (12)°. The compound has two almost planar fragments linked to the S atom: the hydrazone-derivative fragment [(HONC4H6)N-N(H)-] and the tolyl fragment (C7H7-) have maximum deviations from the mean plane through the non-H atoms of 0.0260 (10) and 0.0148 (14) Å, respectively. The two planar fragments make an interplanar angle of 79.47 (5)°. In the crystal, molecules are connected through inversion centers via pairs of N-H...O and O-H...N hydrogen bonds

Improved cosmological constraints on the curvature and equation of state of dark energy

Pan, Nana; Gong, Yungui; Chen, Yun; Zhu, Zong-Hong
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
25.51%
We apply the Constitution compilation of 397 supernova Ia, the baryon acoustic oscillation measurements including the $A$ parameter, the distance ratio and the radial data, the five-year Wilkinson microwave anisotropy probe and the Hubble parameter data to study the geometry of the universe and the property of dark energy by using the popular Chevallier-Polarski-Linder and Jassal-Bagla-Padmanabhan parameterizations. We compare the simple $\chi^2$ method of joined contour estimation and the Monte Carlo Markov chain method, and find that it is necessary to make the marginalized analysis on the error estimation. The probabilities of $\Omega_k$ and $w_a$ in the Chevallier-Polarski-Linder model are skew distributions, and the marginalized $1\sigma$ errors are $\Omega_m=0.279^{+0.015}_{-0.008}$, $\Omega_k=0.005^{+0.006}_{-0.011}$, $w_0=-1.05^{+0.23}_{-0.06}$, and $w_a=0.5^{+0.3}_{-1.5}$. For the Jassal-Bagla-Padmanabhan model, the marginalized $1\sigma$ errors are $\Omega_m=0.281^{+0.015}_{-0.01}$, $\Omega_k=0.000^{+0.007}_{-0.006}$, $w_0=-0.96^{+0.25}_{-0.18}$, and $w_a=-0.6^{+1.9}_{-1.6}$. The equation of state parameter $w(z)$ of dark energy is negative in the redshift range $0\le z\le 2$ at more than $3\sigma$ level. The flat $\Lambda$CDM model is consistent with the current observational data at the $1\sigma$ level.; Comment: 10 figures...

Leptogenesis in an SU(5) x A5 Golden Ratio Flavour Model

Gehrlein, Julia; Petcov, Serguey T.; Spinrath, Martin; Zhang, Xinyi
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
25.47%
In this paper we discuss a minor modification of a previous SU(5) x A5 flavour model which exhibits at leading order golden ratio mixing and sum rules for the heavy and the light neutrino masses. Although this model could predict all mixing angles well it fails in generating a sufficient large baryon asymmetry via the leptogenesis mechanism. We repair this deficit here, discuss model building aspects and give analytical estimates for the generated baryon asymmetry before we perform a numerical parameter scan. Our setup has only a few parameters in the lepton sector. This leads to specific constraints and correlations between the neutrino observables. For instance, we find that in the model considered only the neutrino mass spectrum with normal mass ordering and values of the lightest neutrino mass in the interval 10-18 meV are compatible with the current data on the neutrino oscillation parameters. With the introduction of only one NLO operator, the model can accommodate successfully simultaneously even at 1$\sigma$ level the current data on neutrino masses, on neutrino mixing and the observed value of the baryon asymmetry.; Comment: 22 pages, 7 figures; version published in Nucl. Phys. B

Rest-Frame Optical Emission Lines in z~3.5 Lyman Break selected Galaxies: The Ubiquity of Unusually High [OIII]/Hbeta Ratios at 2 Gyr

Holden, B. P.; Oesch, P. A.; Gonzalez, V. G.; Illingworth, G. D.; Labbe, I.; Bouwens, R.; Franx, M.; van Dokkum, P.; Spitler, L.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
25.51%
We present K-band spectra of rest-frame optical emission lines for 24 star-forming galaxies at z~3.2-3.7 using MOSFIRE on the Keck 1 telescope. Strong rest-frame optical [O III] and Hbeta emission lines were detected in 18 LBGs. The median flux ratio of [O III]5007 to Hbeta is 5.1+/-0.5, a factor of 5-10x higher than in local galaxies with similar stellar masses. The observed Hbeta luminosities are in good agreement with expectations from the estimated star-formation rates, and none of our sources are detected in deep X-ray stacks, ruling out significant contamination by active galactic nuclei. Combining our sample with a variety of LBGs from the literature, including 49 galaxies selected in a very similar manner, we find a high median ratio of [OIII]/Hbeta = 4.8+0.8-1.7. This high ratio seems to be an ubiquitous feature of z~3-4 LBGs, very different from typical local star-forming galaxies at similar stellar masses. The only comparable systems at z~0 are those with similarly high specific star-formation rates, though ~5x lower stellar masses. High specific star-formation rates either result in a much higher ionization parameter or other unusual conditions for the interstellar medium, which result in a much higher [OIII]/Hbeta line ratio. This implies a strong relation between a global property of a galaxy...

$\alpha $-Attractors: Planck, LHC and Dark Energy

Carrasco, John Joseph M.; Kallosh, Renata; Linde, Andrei
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
25.48%
We develop four-parameter supergravity models of inflation and dark energy, constrained so that ${\delta\rho\over \rho}$, $n_s$ and the cosmological constant $\Lambda $ take their known observable values, but where the mass of gravitino $m_{3/2}$ and the tensor-to-scalar ratio $r$ are free parameters. We focus on generalized cosmological $\alpha$-attractor models, with logarithmic Kahler potentials, a nilpotent goldstino and spontaneously broken supersymmetry at the de Sitter minimum. The future data on B-modes will specify the parameter $\alpha$, measuring the geometry of the Kahler, manifold. The string landscape idea for dark energy is supported in these models via an incomplete cancellation of the universal positive goldstino and negative gravitino contribution. The scale of SUSY breaking M related to the mass of gravitino in our models is a controllable parameter, independent on the scale of inflation, it will be constrained by LHC data and future collider Energy-frontier experiments.; Comment: 18 pages, 5 figures (2 new figures added)

A Measurement of the Cosmic Microwave Background Damping Tail from the 2500-square-degree SPT-SZ survey

Story, K. T.; Reichardt, C. L.; Hou, Z.; Keisler, R.; Aird, K. A.; Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Cho, H-M.; Crawford, T. M.; Crites, A. T.; de Haan, T.; Dobbs, M. A.; Dudley, J.; Follin, B.; George, E. M.; Halverson, N. W.;
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
25.49%
We present a measurement of the cosmic microwave background (CMB) temperature power spectrum using data from the recently completed South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) survey. This measurement is made from observations of 2540 deg$^2$ of sky with arcminute resolution at $150\,$GHz, and improves upon previous measurements using the SPT by tripling the sky area. We report CMB temperature anisotropy power over the multipole range $650<\ell<3000$. We fit the SPT bandpowers, combined with the seven-year Wilkinson Microwave Anisotropy Probe (WMAP7) data, with a six-parameter LCDM cosmological model and find that the two datasets are consistent and well fit by the model. Adding SPT measurements significantly improves LCDM parameter constraints; in particular, the constraint on $\theta_s$ tightens by a factor of 2.7. The impact of gravitational lensing is detected at $8.1\, \sigma$, the most significant detection to date. This sensitivity of the SPT+WMAP7 data to lensing by large-scale structure at low redshifts allows us to constrain the mean curvature of the observable universe with CMB data alone to be $\Omega_k=-0.003^{+0.014}_{-0.018}$. Using the SPT+WMAP7 data, we measure the spectral index of scalar fluctuations to be $n_s=0.9623 \pm 0.0097$ in the LCDM model...

Probing the Mass Distributions in NGC 1407 and Its Associated Group with the X-ray Imaging Spectroscopic and Optical Photometric and Line-strength Indices Data

Zhang, Zhongli; Xu, Haiguang; Wang, Yu; An, Tao; Xu, Yueheng; Wu, Xiang-Ping
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 31/10/2006
Relevância na Pesquisa
35.47%
We present a study of the mass distributions in the bright E0 galaxy NGC 1407 and its associated group by analyzing the high quality Chandra and ROSAT X-ray spectroscopic data. In order to probe the stellar mass distribution we calculated the B-band mass-to-light ratio profile by comparing the observed line-strength indices and multi-color photometric data with different stellar synthesis model predictions. We find that the gas is single-phase with a temperature of ~0.7 keV within 1Re. Outside 1Re the gas temperature increases quickly outwards to >1 keV, indicating its group origin. We reveal that the X-ray surface brightness profile shows a central excess in the innermost region, and on both the total mass and dark matter profiles there is a flattened feature at about <1Re, which coincides with the gas temperature transition from the galactic level to the group level. The total mass and dark matter distributions within 0.85Re are cuspy and can be approximated by power-law profiles with indices of ~2, which are marginally consistent with the generalized NFW profiles with zeta=2. The mass in outer regions can be well fitted by a single NFW profile, with the derived concentration parameter c=18.6\pm1.5. We find that the NGC 1407 group has a baryon-dominated core...

The ILIUM forward modelling algorithm for multivariate parameter estimation and its application to derive stellar parameters from Gaia spectrophotometry

Bailer-Jones, C. A. L.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
35.43%
I introduce an algorithm for estimating parameters from multidimensional data based on forward modelling. In contrast to many machine learning approaches it avoids fitting an inverse model and the problems associated with this. The algorithm makes explicit use of the sensitivities of the data to the parameters, with the goal of better treating parameters which only have a weak impact on the data. The forward modelling approach provides uncertainty (full covariance) estimates in the predicted parameters as well as a goodness-of-fit for observations. I demonstrate the algorithm, ILIUM, with the estimation of stellar astrophysical parameters (APs) from simulations of the low resolution spectrophotometry to be obtained by Gaia. The AP accuracy is competitive with that obtained by a support vector machine. For example, for zero extinction stars covering a wide range of metallicity, surface gravity and temperature, ILIUM can estimate Teff to an accuracy of 0.3% at G=15 and to 4% for (lower signal-to-noise ratio) spectra at G=20. [Fe/H] and logg can be estimated to accuracies of 0.1-0.4dex for stars with G<=18.5. If extinction varies a priori over a wide range (Av=0-10mag), then Teff and Av can be estimated quite accurately (3-4% and 0.1-0.2mag respectively at G=15)...

The enrichment history of the intracluster medium: a Bayesian approach

Andreon, S.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 04/09/2012
Relevância na Pesquisa
35.44%
This work measures the evolution of the iron content in galaxy clusters by a rigorous analysis of the data of 130 clusters at 0.1

Searching for periodic sources with LIGO

Brady, Patrick R.; Creighton, Teviet; Cutler, Curt; Schutz, Bernard F.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 24/02/1997
Relevância na Pesquisa
25.48%
We investigate the computational requirements for all-sky, all-frequency searches for gravitational waves from spinning neutron stars, using archived data from interferometric gravitational wave detectors such as LIGO. These sources are expected to be weak, so the optimal strategy involves coherent accumulaton of signal-to-noise using Fourier transforms of long stretches of data (months to years). Earth-motion-induced Doppler shifts, and intrinsic pulsar spindown, will reduce the narrow-band signal-to-noise by spreading power across many frequency bins; therefore, it is necessary to correct for these effects before performing the Fourier transform. The corrections can be implemented by a parametrized model, in which one does a search over a discrete set of parameter values. We define a metric on this parameter space, which can be used to determine the optimal spacing between points in a search; the metric is used to compute the number of independent parameter-space points Np that must be searched, as a function of observation time T. The number Np(T) depends on the maximum gravitational wave frequency and the minimum spindown age tau=f/(df/dt) that the search can detect. The signal-to-noise ratio required, in order to have 99% confidence of a detection...

Parameter constraints in a near-equipartition model with multi-frequency \emph{NuSTAR}, \emph{Swift} and \emph{Fermi-LAT} data from 3C 279

Yan, Dahai; Zhang, Li; Zhang, Shuang-Nan
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 16/09/2015
Relevância na Pesquisa
25.5%
Precise spectra of 3C 279 in the 0.5-70 keV range, obtained during two epochs of \emph{Swift} and \emph{NuSTAR} observations, are analyzed using a near-equipartition model. We apply a one-zone leptonic model with a three-parameter log-parabola electron energy distribution (EED) to fit the \emph{Swift} and \emph{NuSTAR} X-ray data, as well as simultaneous optical and \emph{Fermi}-LAT $\gamma$-ray data. The Markov Chain Monte Carlo (MCMC) technique is used to search the high-dimensional parameter space and evaluate the uncertainties on model parameters. We show that the two spectra can be successfully fit in near-equipartition conditions, defined by the ratio of the energy density of relativistic electrons to magnetic field $\zeta_{\rm e}$ being close to unity. In both spectra, the observed X-rays are dominated by synchrotron-self Compton photons, and the observed $\gamma$ rays are dominated by Compton scattering of external infrared photons from a surrounding dusty torus. Model parameters are well constrained. From the low state to the high state, both the curvature of the log-parabola width parameter and the synchrotron peak frequency significantly increase. The derived magnetic fields in the two states are nearly identical ($\sim1$\ G)...

A Novel, Fully Automated Pipeline for Period Estimation in the EROS 2 Data Set

Protopapas, Pavlos; Huijse, Pablo; Estevez, Pablo A.; Zegers, Pablo; Principe, Jose C.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 04/12/2014
Relevância na Pesquisa
35.4%
We present a new method to discriminate periodic from non-periodic irregularly sampled lightcurves. We introduce a periodic kernel and maximize a similarity measure derived from information theory to estimate the periods and a discriminator factor. We tested the method on a dataset containing 100,000 synthetic periodic and non-periodic lightcurves with various periods, amplitudes and shapes generated using a multivariate generative model. We correctly identified periodic and non-periodic lightcurves with a completeness of 90% and a precision of 95%, for lightcurves with a signal-to-noise ratio (SNR) larger than 0.5. We characterize the efficiency and reliability of the model using these synthetic lightcurves and applied the method on the EROS-2 dataset. A crucial consideration is the speed at which the method can be executed. Using hierarchical search and some simplification on the parameter search we were able to analyze 32.8 million lightcurves in 18 hours on a cluster of GPGPUs. Using the sensitivity analysis on the synthetic dataset, we infer that 0.42% in the LMC and 0.61% in the SMC of the sources show periodic behavior. The training set, the catalogs and source code are all available in http://timemachine.iic.harvard.edu.

Searching for periodic sources with LIGO

Brady, Patrick R.; Creighton, Teviet; Cutler, Curt; Schutz, Bernard F.
Fonte: American Physical Society Publicador: American Physical Society
Tipo: Article; PeerReviewed Formato: application/pdf
Publicado em 15/02/1998
Relevância na Pesquisa
25.53%
We investigate the computational requirements for all-sky, all-frequency searches for gravitational waves from spinning neutron stars, using archived data from interferometric gravitational wave detectors such as LIGO. These sources are expected to be weak, so the optimal strategy involves coherent accumulation of signal-to-noise using Fourier transforms of long stretches of data (months to years). Earth-motion-induced Doppler shifts, and intrinsic pulsar spindown, will reduce the narrow-band signal-to-noise by spreading power across many frequency bins; therefore, it is necessary to correct for these effects before performing the Fourier transform. The corrections can be implemented by a parametrized model, in which one does a search over a discrete set of parameter values (points in the parameter space of corrections). We define a metric on this parameter space, which can be used to determine the optimal spacing between points in a search; the metric is used to compute the number of independent parameter-space points Np that must be searched, as a function of observation time T. This method accounts automatically for correlations between the spindown and Doppler corrections. The number Np(T) depends on the maximum gravitational wave frequency and the minimum spindown age τ=f/ḟ that the search can detect. The signal-to-noise ratio required...

A Measurement of the Cosmic Microwave Background Damping Tail from the 2500-Square-Degree SPT-SZ Survey

Story, K. T.; Lueker, M.; Padin, S.; Vieira, J. D.
Fonte: American Astronomical Society Publicador: American Astronomical Society
Tipo: Article; PeerReviewed Formato: application/pdf; application/pdf
Publicado em 10/12/2013
Relevância na Pesquisa
25.48%
We present a measurement of the cosmic microwave background (CMB) temperature power spectrum using data from the recently completed South Pole Telescope Sunyaev-Zel'dovich (SPT-SZ) survey. This measurement is made from observations of 2540 deg^2 of sky with arcminute resolution at 150 GHz, and improves upon previous measurements using the SPT by tripling the sky area. We report CMB temperature anisotropy power over the multipole range 650 < ℓ < 3000. We fit the SPT bandpowers, combined with the 7 yr Wilkinson Microwave Anisotropy Probe (WMAP7) data, with a six-parameter ΛCDM cosmological model and find that the two datasets are consistent and well fit by the model. Adding SPT measurements significantly improves ΛCDM parameter constraints; in particular, the constraint on θ_s tightens by a factor of 2.7. The impact of gravitational lensing is detected at 8.1σ, the most significant detection to date. This sensitivity of the SPT+WMAP7 data to lensing by large-scale structure at low redshifts allows us to constrain the mean curvature of the observable universe with CMB data alone to be Ω_k=-0.003^(+0.014)_(-0.018). Using the SPT+WMAP7 data, we measure the spectral index of scalar fluctuations to be n_s = 0.9623 ± 0.0097 in the ΛCDM model...