Testing for Serial Correlation in Least Squares Regression. Ii

Durbin, J.; Watson, G. S.

doi:10.1093/biomet/38.1-2.159

Cited by 2,235 publications

(532 citation statements)

References 25 publications

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“…This method is designed to find a spline representation for noisy data without allowing the spline to follow every noise feature. This is achieved by starting with an interpolating spline (one knot at every observed data point) and iteratively removing knots to optimize the Durbin-Watson statistic (Durbin & Watson 1950, 1951, which tests for serial correlation in the least squares regression. When applying SNPy we defined a separate spline curve for the F160W, F125W, and F105W bands.…”

Section: Time Delay Measurements With Flexible Light Curve Modelsmentioning

confidence: 99%

Sn Refsdal: Photometry and Time Delay Measurements of the First Einstein Cross Supernova

Rodney

Strolger

Kelly

et al. 2016

ApJ

102

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We present the first year of Hubble Space Telescope imaging of the unique supernova (SN) "Refsdal," a gravitationally lensed SN at z=1.488±0.001 with multiple images behind the galaxy cluster MACS J1149.6 +2223. The first four observed images of SN Refsdal (images S1-S4) exhibited a slow rise (over ∼150 days) to reach a broad peak brightness around 2015 April 20. Using a set of light curve templates constructed from SN 1987A-like peculiar Type II SNe, we measure time delays for the four images relative to S1 of 4±4 (for S2), 2±5 (S3), and 24±7 days (S4). The measured magnification ratios relative to S1 are 1.15±0.05 (S2), 1.01±0.04 (S3), and 0.34±0.02 (S4). None of the template light curves fully captures the photometric behavior of SN Refsdal, so we also derive complementary measurements for these parameters using polynomials to represent the intrinsic light curve shape. These more flexible fits deliver fully consistent time delays of 7±2 (S2), 0.6±3 (S3), and 27±8 days (S4). The lensing magnification ratios are similarly consistent, measured as 1.17±0.02 (S2), 1.00±0.01 (S3), and 0.38±0.02 (S4). We compare these measurements against published predictions from lens models, and find that the majority of model predictions are in very good agreement with our measurements. Finally, we discuss avenues for future improvement of time delay measurements-both for SN Refsdal and for other strongly lensed SNe yet to come.

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Section: Time Delay Measurements With Flexible Light Curve Modelsmentioning

confidence: 99%

Sn Refsdal: Photometry and Time Delay Measurements of the First Einstein Cross Supernova

Rodney

Strolger

Kelly

et al. 2016

ApJ

102

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“…Intensity decay curves were fitted as a sum of exponential terms: also includes statistical and plotting subroutine packages (OConnor & Phillips, 1984). The goodness of the fit of a given set of observed data and the chosen function was evaluated by the reduced x2 ratio, the weighted residuals (Lampert et al, 1983), the autocorrelation function of the weighted residuals (Grinvald & Steinberg, 1974), the runs test (Hamburg, 1989, and the Durbin-Watson parameters (Durbin & Watson, 1950, 1951. A fit was considered acceptable when plots of the weighted residuals and the autocorrelation function showed random deviation about zero with a x2 value not more than 1.5.…”

Section: 'Vv Crlvhmentioning

confidence: 99%

Fluorophore environments in membrane-bound probes: A red edge excitation shift study

Chattopadhyay

Mukherjee²

1993

Biochemistry

142

158

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A shift in the wavelength of maximum fluorescence emission toward higher wavelengths, caused by a shift in the excitation wavelength toward the red edge of the absorption band, is termed the Red Edge Excitation Shift (REES). This effect is mostly observed with polar fluorophores in motionally restricted media such as very viscous solutions or condensed phases. In this paper, we report the red edge excitation shift of a membrane-bound phospholipid molecule whose headgroup is covalently labeled with a 7-nitrobenz-2-oxa-1,3-diazol-4-y1 (NBD) moiety. When incorporated into model membranes of dioleoyl-sn-glycero-3-phosphocholine (DOPC), the NBD-labeled phospholipid (NBD-PE), exhibits a red edge excitation shift of 10 nm. In addition, fluorescence polarization of NBD-PE in membranes shows both excitation and emission wavelength dependence. The nonpolar membrane probe 1,6-diphenyl-1,3,5-hexatriene (DPH) does not show red edge excitation shift in model membranes. The lifetime of NBD-PE in DOPC vesicles was found to be dependent on both excitation and emission wavelengths. These wavelength-dependent lifetimes are correlated to the reorientation of solvent dipoles around the excited-state dipole of the NBD moiety in the membrane. The magnitude of the red shift in the emission maximum for NBD-PE was found to be independent of temperature, between 12 and 54 O C , and of the physical state (gel or fluid) of the membrane. Taken together, these observations are indicative of the motional restriction experienced by this fluorophore in the membrane. Red edge excitation shift promises to be a powerful tool in probing membrane organization and dynamics.Organized molecular assemblies such as membranes can be considered as large cooperative units with characteristics very different from the individual structural units which constitute them. Fluorescence spectroscopy has been one of the principal techniques to study organization and dynamics of biological and model membranes because of its suitable time scale, noninvasive nature, and intrinsic sensitivity (Radda, 1975;Lakowicz, 1980Lakowicz, , 1981. For a fluorophore in a bulk nonviscous solvent, the dipolar relaxation of the solvent molecules around the fluorophore in the excited state is much faster than the fluorescence lifetime. The fluorescence decay rates and the wavelength of maximum emission, in such a case, are therefore usually independent of the excitation wavelength. However, these parameters do show excitation wavelength dependence if the dipolar relaxation of the solvent molecules is slow in the excited state, such that the relaxation time is comparable to or longer than the fluorescence lifetime (Chen, 1967;Fletcher, 1968;Galley & Purkey, 1970;Rubinov & Tomin, 1970;Castelli & Forster, 1973;Itoh & Azumi, 1975;Demchenko, 1982; Lakowicz & Keating-Nakamoto, 1984). Such a shift in the wavelength of maximum emission toward higher wavelengths, caused by a shift in the excitation wavelength toward the red edge of the absorption band, is termed the red edge excitatio...

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“…88,89 Violation of the premises related to regression analysis were analyzed: normality by the Ryan and Joiner test, 90 homoscedasticity by the modified Levene test 91 and the Brown and Watson test 92 and independence of the regression residues by the Durbin and Watson test. 93 An F-test was conducted to verify the fit to the linear model by means of the significance evaluation of the regression and deviation from linearity. 94 …”

Section: Validation Of the Methodsmentioning

confidence: 99%

“…The results of the Levene test were not significant (p > 0.05) in all curves examined. The independence of the regression residues was evidenced by the Durbin-Watson test 93 since the distribution of the points did not show positive or negative tendencies. Therefore, the use of the OLSM was adequate for estimation of the regression parameters.…”

Section: Limit Of Detection Limit Of Quantification and Linearitymentioning

confidence: 99%

Determination of carbamates in beverages by liquid-liquid extraction with low temperature partitioning and liquid chromatography

Goulart¹,

Alves²,

Paula³

et al. 2012

J. Braz. Chem. Soc.

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Carbamatos são os pesticidas mais frequentemente encontrados em alimentos e bebidas de coloração escura em casos de intoxicação acidental ou intencional. Neste trabalho, extração líquido-líquido com partição em baixa temperatura (LLE-LTP) foi otimizada e validada para determinação dos carbamatos aldicarb, carbofuran e carbaril em bebidas de sucos de uva e leite achocolatado. Este método envolve a extração com acetonitrila, partição líquido-líquido em baixa temperatura e análise por cromatografia líquida de alta eficiência com detecção ultravioleta (HPLC-UV). O método é rápido, eficiente e de baixo custo, emprega pequenos volumes de solvente por amostra e não necessita de limpeza dos extratos. O método de extração foi seletivo e apresentou porcentagens de extração acima de 90%. As premissas relacionadas com os testes estatísticos de linearidade foram verificadas e confirmadas. O método de extração e análise foi validado com resultados satisfatórios e pode ser aplicado em análises de rotina e forenses.Carbamates are the pesticides most commonly found in dark colored foods and beverages in cases of accidental or intentional poisoning. In this work, the liquid-liquid extraction with low temperature partitioning (LLE-LTP) was optimized and validated for determination of the carbamates aldicarb, carbofuran and carbaryl in grape juice and chocolate milk beverages. This method involved extraction with acetonitrile, liquid-liquid partition at low temperature and the analysis by high performance liquid chromatography with ultraviolet detection (HPLC-UV). The method is rapid, efficient and of low-cost, employing small volumes of solvent per sample and requiring no cleanup of the extracts. The extraction methodology was selective and presented recovery percentages above 90%. The premises related to the statistical linearity tests were checked and confirmed. The method of extraction and analysis was validated with satisfactory results, and may be applied in forensic and routine analysis Keywords: carbamates, low temperature partitioning, high performance liquid chromatography, sample preparation, validation IntroductionCarbamate insecticides are widely used in gardening and agriculture due to their broad spectrum of activity and relatively short environmental persistence. However, they are potentially toxic to humans, particularly in the context of intentional self-poisoning. 1,2 Carbamates are found as commercialized products for agricultural practices and some compounds of this group, with their respective commercial names are: carbaryl (Sevin ® ), aldicarb (Temik ® ) and carbofuran (Furadan ® ). From these, aldicarb stands out as the main target on the list of controlled pesticides of the United States Environmental Protection Agency (EPA) due to its elevated toxicity to mammals. 3,4 The maximum residue level (MRL) of aldicarb 5,6 and carbofuran 6 in water is 10 and 7 μg L -1 , respectively. In Goulart et al. 1155 Vol. 23, No. 6, 2012 milk, the MRLs established for aldicarb, 7,8 Exposures may occur accidentally, with ...

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Testing for Serial Correlation in Least Squares Regression. Ii

Cited by 2,235 publications

References 25 publications

Sn Refsdal: Photometry and Time Delay Measurements of the First Einstein Cross Supernova

Sn Refsdal: Photometry and Time Delay Measurements of the First Einstein Cross Supernova

Fluorophore environments in membrane-bound probes: A red edge excitation shift study

Determination of carbamates in beverages by liquid-liquid extraction with low temperature partitioning and liquid chromatography

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