Impact of parental weight status on a school-based weight management programme designed for Mexican-American children.

BACKGROUND: While overweight and obese children are more likely to have overweight or obese parents, less is known about the effect of parental weight status on children's success in weight management programmes. OBJECTIVES: This study was a secondary data analysis of a randomized controlled trial and investigated the impact of having zero, one or two obese parents on children's success in a school-based weight management programme. METHODS: Sixty-one Mexican-American children participated in a 24-week school-based weight management intervention which took place in 2005-2006. Children's heights and weights were measured at baseline, 3, 6 and 12 months. Parental weight status was assessed at baseline. Repeated measures anova and ancova were conducted to compare changes in children's weight within and between groups, respectively. RESULTS: Within-group comparisons revealed that the intervention led to significant decreases in standardized body mass index (zBMI) for children with zero (F = 23.16, P < .001) or one obese (F = 4.99, P < .05) parent. Between-group comparisons indicated that children with zero and one obese parents demonstrated greater decreases in zBMI compared to children with two obese parents at every time point. CONCLUSIONS: The school-based weight management programme appears to be most efficacious for children with one or no obese parents compared to children with two obese parents. These results demonstrate the need to consider parental weight status when engaging in childhood weight management efforts.

Method for correcting the wavelength misalignment in measured ultraviolet spectra.

A new method for correcting the wavelength misalignment in measured UV spectra is presented. It is based on a comparison between measured irradiances and irradiances computed from a radiative transfer code for a set of given atmospheric and solar conditions (250 < Dobson units < 450, 30 degrees < solar zenith angle < 75 degrees ). Results of tests run with spectra recorded on a clear-sky day by two spectroradiometers in a French UV spectral network station are analyzed. Applying the method once reduces shift to less than 0.05 nm. The smoothing included in the method enables detection of aberrant irradiance values and then completion of an initial quality control of measured spectra. A technique for assessing the instruments' slit function is also presented. The key algorithms needed to build a computer code based on this method are given.

Influence of the environment reflectance on the ultraviolet zenith radiance for cloudless sky.

A three-dimensional Monte Carlo code is used to compute the ultraviolet zenith sky radiance; the code is validated by comparison with a successive-orders-of-scattering code. The amplifications of global irradiance, diffuse irradiance, and zenith radiance that are due to multiple reflectances between a snow-covered ground surface and the atmosphere are compared. For an inhomogeneous Lambertian surface, the contribution of the site environment is analyzed; it depends slightly on the atmospheric turbidity and on the surface reflectance distribution. However, in most cases one can expect approximately 12-15% of the reflected photon contribution to come from within 1 km about the observation site, 25-30% come from areas from 1 to 5 km from the site, 43-47% from 5 to 30 km, and still 10-15% reflected at larger distances. An average contribution function is proposed and used to compute an effective reflectance, which permits retrieval of the sky radiance within 2-4% with a one-dimensional model.

Methodology for the independent calibration of Raman backscatter water-vapor lidar systems.

We present a method for the independent calibration of Raman backscatter water-vapor lidar systems. Particular attention is given to the resolution of instrumental changes in the short and the long terms. The method reposes on the decomposition of the instrument function, which allows the lidar calibration coefficient to be re-expressed as the product of two terms, one describing the instrumental transmission and detection efficiency and the other describing the wavelength-dependent convolution of the Raman backscatter cross sections with the instrument function. The origins of changes in instrument response necessitate the experimental determination of the system detection efficiency. Two external light sources for calibration are assessed: zenith observation of diffuse sunlight and a xenon arc lamp. The results favor use of the diffuse-sunlight measurement but highlight the need for simultaneous sunphotometer measurements to constrain modeled aerosol optical properties. Quantum mechanical models of the Raman cross sections are described, and errors in determining the cross sections and their convolution with the instrument function are discussed in detail. The calibration coefficients deduced by using the independent method are compared with coefficients deduced from Vaisala H-Humicap radiosonde measurements. These results agree to within current calibration errors (15%, unconstrained aerosol parameters), and a change in calibration coefficient following instrument modification is reproduced satisfactorily. Results from modeling and intercomparison studies are extended to estimate the calibration accuracy and the precision of the diffuse-sunlight method with constrained modeled aerosol parameters. Changes in the calibration coefficient in the short and the long terms should be resolved to 4(6)% and 6(9)%, respectively, which is comparable or better than the precision of existing dependent methods of calibration. The reduction of the absolute calibration error remains an outstanding issue for all calibration methods.

Modeling of the influence of snow reflectance on ultraviolet irradiance for cloudless sky.

The amplification of UV irradiance at the Earth's surface that is due to successive reflections between the snow-covered ground and the scattering atmosphere is analyzed by a method based on decoupling the atmosphere and the surface functions. For a uniform Lambertian surface the amplification factor for the global irradiance depends only on the product of the surface reflectance and the atmospheric backscatter. It varies with wavelength, reaching a maximum near 320 nm; this maximum is close to 50% for clean snow. In UV-B the amplification depends strongly on tropospheric ozone. For non-Lambertian, nonuniform surfaces it is possible, by the same method, to define effective or average reflectances.

Validation of the ORA spatial inversion algorithm with respect to the Stratospheric Aerosol and Gas Experiment II data.

We present the results of a comparison of the total extinction altitude profiles measured at the same time and at same location by the ORA (Occultation Radiometer) and Stratospheric Aerosol and Gas Experiment II solar occultation experiments at three different wavelengths. A series of 25 events for which the grazing points of both experiments lie within a 2 degrees window has been analyzed. The mean relative differences observed over the altitude range 15-45 km are -8.4%, 1.6%, and 3% for the three channels (0.385, 0.6, and 1.02 microm). Some systematic degradation occurs below 20 km (as the result of signal saturation and possible cloud interference) and above 40 km (low absorption). The fair general agreement between the extinction profiles obtained by two different instruments enhances our confidence in the results of the ORA experiment and of the recently developed vertical inversion algorithm applied to real data.

Comparison between measurements and modeling of UV-B irradiance for clear sky: a case study.

We compare the TJV-B global and direct irradiances computed with a radiative transfer model (discrete ordinate method) and measured during a European intercomparison campaign in Greece in July 1991, with clear sky. The agreement between the model and the measurements is within 6%. The sensitivity of the model to the accuracy of the input parameters as well as the potential of modeling for instrument calibration is discussed.

Absorption profile of a planetary atmosphere: a proposal for a scattering independent determination.

The use of scattering theory to infer atmospheric optical parameters requires the separation of absorption and scattering. It is demonstrated that a gradient flux relation exists that would provide the absorption (altitude) profile independently of scattering and irrespective of the state of polarization of the light field. The relation is derived for an atmosphere of plane-parallel or spherical geometry and for broad (continuum) and narrow (spectral line) frequency bands. The results are shown to hold, in particular, for the polarizations induced by both Rayleigh and Mie scattering in the field. Experimental setups are proposed for each of the cases considered of atmospheric geometry and frequency bandwidth. A final discussion considers the relevance of the present determination of the atmospheric absorption profile to the related problems of aerosol relative concentration, interpretation of radiometric and spectrometric data formed in the presence of scattering, clouds morphology, and radiative heat budget of the atmosphere.