Evaluation of forward-modelled attenuated backscatter using an urban ceilometer network in London under clear-sky conditions

Numerical weather prediction (NWP) of urban aerosols is increasingly sophisticated and accurate. In the absence of large particles (e.g. rain, cloud droplets), information on atmospheric aerosols can be obtained from single wavelength automatic lidars and ceilometers (ALC) that measure profiles of attenuated backscatter (βo). To assess the suitability of ALC profile observations for forecast evaluation and data assimilation, a forward operator is required to convert model variables into the measured quantity. Here, an aerosol forward operator (aerFO) is developed and tested with Met Office NWP data (UKV 1.5 km) to obtain synthetic attenuated backscatter profiles (βm). aerFO requires as input the profiles of bulk aerosol mass mixing ratio and relative humidity to compute βm, plus air temperature and pressure to calculate the effect of water vapour absorption. Bulk aerosol characteristics (e.g. mean radius and number concentration) are used to estimate optical properties. ALC profile observations in London are used to assess βm. A wavelength-dependent extinction enhancement factor accounts for the change in optical properties due to aerosol swelling. Sensitivity studies show the aerFO unattenuated backscatter is very sensitive to the aerosol mass and relative humidity above ~60-80 %. The extinction efficiency is sensitive to the choice of aerosol constituents and to ALC wavelength.Given aerosol is a tracer for boundary layer dynamics, application of the aerFO has proven very useful to evaluate the performance of urban surface parameterisation schemes and their ability to drive growth of the mixing layer. Implications of changing the urban surface scheme within the UKV is explored using two spring cases. For the original scheme, morning βm is too high probably because of delayed vertical mixing. The new scheme reduced this persistence of high morning βm, demonstrating the importance of surface heating processes. Analysis of profiles at five sites on 12 clear-sky days shows a positive, statistically significant relation between the differences of modelled and measured near-surface attenuated backscatter [βm - βo] and near-surface aerosol mass. This suggests errors in near-surface attenuated backscatter can be attributed to errors in the amount of aerosol estimated by the NWP scheme. Correlation increases when cases of high relative humidity in the NWP model are excluded. Given the impact on aerosol optical properties demonstrated, results suggest the use of a fixed, bulk aerosol for urban areas in the UKV should be revisited and the lidar ratio should be constrained. As quality of the observed attenuated backscatter is demonstrated to be critical for performing model evaluation, careful sensor operation and data processing is vital to avoid false conclusions to be drawn about model performance

Helping patients discuss CINV management : development of a patient charter

In April 2012, an Expert Group of specialist cancer nurses working in a variety of settings (e.g. chemotherapy delivery, chemotherapy service design, research, nurse leadership and patient information/advocacy) participated in telephone/web-based meetings, with the aim of sharing current experience of chemotherapy-induced nausea and vomiting (CINV) management, and reaching a consensus on the development of a Patient Charter, designed to help patients understand CINV management, and setting out key questions they may wish to ask their healthcare professionals

Integrating HIV/AIDS and TB Efforts: The Challenge for the President's AIDS Initiative

Surveys the current state of HIV/TB co-infection in each of the 14 countries targeted for significant U.S. government assistance. Outlines the benefits of better integrating TB and HIV/AIDS efforts, and calls for a strong response to both epidemics

A robust automated technique for operational calibration of ceilometers using the integrated backscatter from totally attenuating liquid clouds

A simple and robust method for calibrating ceilometers has been tested in an operational environment demonstrating that the calibrations are stable to better than ± 5 % over a period of a year. The method relies on using the integrated backscatter (B) from liquid clouds that totally extinguish the ceilometer signal; B is inversely proportional to the lidar ratio (S) of the backscatter to the extinction for cloud droplets. The calibration technique involves scaling the observed backscatter so that B matches the predicted value for S of 18.8 ± 0.8 sr for cloud droplets, at ceilometer wavelengths. For accurate calibration, care must be taken to exclude any profiles having targets with different values of S, such as drizzle drops and aerosol particles, profiles that do not totally extinguish the ceilometer signal, profiles with low cloud bases that saturate the receiver, and any profiles where the window transmission or the lidar pulse energy is low. A range dependent multiple scattering correction that depends on the ceilometer optics should be applied to the profile. A simple correction for water vapour attenuation for ceilometers operating at around 910 nm wavelength is applied to the signal using the vapour profiles from a forecast analysis. For a generic ceilometer in the UK the 90-day running mean of the calibration coefficient over a period of 20 months is constant to within 3 % with no detectable annual cycle, thus confirming the validity of the humidity and multiple scattering correction. For Gibraltar, where cloud cover is less prevalent than in the UK, the 90-day running mean calibration coefficient was constant to within 4 %. The more sensitive ceilometer model operating at 1064 nm is unaffected by water vapour attenuation but is more prone to saturation in liquid clouds. We show that reliable calibration is still possible, provided the clouds used are above a certain altitude. The threshold is instrument dependent but is typically around 2 km. We also identify a characteristic signature of saturation, and remove any profiles with this signature. Despite the more restricted sample of cloud profiles, a robust calibration is readily achieved, and, in the UK, the running mean 90-day calibration coefficients varied by about 4 % over a period of one year. The consistency of profiles observed by nine pairs of co-located ceilometers in the UK Met Office network operating at around 910 nm and 1064 nm provided independent validation of the calibration technique. EUMETNET is currently networking 700 European ceilometers so they can provide ceilometer profiles in near real time to European weather forecast centres and has adopted the cloud calibration technique described in this paper for ceilometers with a wavelength of around 910 nm

Film extrusion of sunflower protein isolate

Film extrusion of sunflower protein isolate (SFPI) was studied. The influence of die temperature (85 to 160°C), water and glycerol contents were investigated through appearance, mechanical and thermo-mechanical properties and swelling behavior in water of films. It was demonstrated that highest temperature, well above SFPI denaturation temperature in the compound, highest glycerol content (70 parts for 100 parts of SFPI) and medium water content (20 parts for 100 parts of SFPI) gave the most regular and smoothest film (as seen on SEM micrographs). Its ultimate tensile strength, Young’s modulus and strain at break were respectively: 3.2 MPa, 17.7 MPa and 73%. Soaked in water, its swelling was about 186% w/w but the film was quiet insoluble. Effect of temperature and plasticizer content were discussed in relation to the kinetic of SFPI denaturation. These first results are very promising for the development of biodegradable protein-based films

Recommendations for processing atmospheric attenuated backscatter profiles from Vaisala CL31 ceilometers

Ceilometer lidars are used for cloud base height detection, to probe aerosol layers in the atmosphere (e.g. detection of elevated layers of Saharan dust or volcanic ash), and to examine boundary layer dynamics. Sensor optics and acquisition algorithms can strongly influence the observed attenuated backscatter profiles; therefore, physical interpretation of the profiles requires careful application of corrections. This study addresses the widely deployed Vaisala CL31 ceilometer. Attenuated backscatter profiles are studied to evaluate the impact of both the hardware generation and firmware version. In response to this work and discussion within the CL31/TOPROF user community (TOPROF, European COST Action aiming to harmonise ground-based remote sensing networks across Europe), Vaisala released new firmware (versions 1.72 and 2.03) for the CL31 sensors. These firmware versions are tested against previous versions, showing that several artificial features introduced by the data processing have been removed. Hence, it is recommended to use this recent firmware for analysing attenuated backscatter profiles. To allow for consistent processing of historic data, correction procedures have been developed that account for artefacts detected in data collected with older firmware. Furthermore, a procedure is proposed to determine and account for the instrument-related background signal from electronic and optical components. This is necessary for using attenuated backscatter observations from any CL31 ceilometer. Recommendations are made for the processing of attenuated backscatter observed with Vaisala CL31 sensors, including the estimation of noise which is not provided in the standard CL31 output. After taking these aspects into account, attenuated backscatter profiles from Vaisala CL31 ceilometers are considered capable of providing valuable information for a range of applications including atmospheric boundary layer studies, detection of elevated aerosol layers, and model verification

Mexican-Origin Youth\u27s Risk Behavior from Adolescence to Young Adulthood: The Role of Familism Values

Engagement in risk behavior has implications for individuals\u27 academic achievement, health, and well-being, yet there is a paucity of developmental research on the role of culturally-relevant strengths in individual and family differences in risk behavior involvement among ethnic minority youth. In this study, we used a longitudinal cohort-sequential design to chart intraindividual trajectories of risk behavior and test variation by gender and familism values in 492 youth from 12 to 22 years of age. Participants were older and younger siblings from 246 Mexican-origin families who reported on their risk behaviors in interviews spaced over eight years. Multilevel cohort-sequential growth models revealed that youth reported an increase in risk behavior from 12 to 18 years of age, and then a decline to age 22. Male youth reported greater overall levels and a steeper increase in risk behavior from ages 12 to 18, compared to female youth. For familism values, on occasions when youth reported higher levels, they also reported lower levels of risk behavior (i.e., within-person effect). For sibling dyads characterized by higher average levels of familism values, youth reported lower average levels of risk behavior (i.e., between-family effect). Findings provide unique insights into risk behavior from adolescence to young adulthood among Mexican-origin youth

Mexican-origin Youths’ Trajectories of Depressive Symptoms: The Role of Familism Values

Purpose—To describe Mexican-origin youths’ trajectories of depressive symptoms from early to late adolescence and examine the role of three aspects of familism values: supportive, obligation, and referent familism. Methods—Mexican-origin adolescents (N = 492) participated in home interviews and provided self-reports of depressive symptoms and cultural values at four assessments across an 8-year span. Using a cohort sequential design and accounting for the nesting within the 246 families (2 youth per family), we examined depressive symptoms from ages 12 to 22 years and the within-person, between-sibling, and between-family effects of familism values. Results—Mexican-origin males’ depressive symptoms decreased across adolescence, while females’ symptoms exhibited a cubic pattern of change. Results revealed that increases in supportive and referent familism values within individuals and across families related to lower levels of depressive symptoms. Findings were most pronounced for referent familism values, as a between-sibling effect also emerged. Obligation familism values were not associated with depressive symptoms. Conclusions—Our findings provide important descriptive information about Mexican-origin youths’ depressive symptoms and highlight the promotive role of familism values

Spatial variability of forward modelled attenuated backscatter in clear‐sky conditions over a megacity: implications for observation network design

Sensors that measure the attenuated backscatter coefficient (e.g. automatic lidars and ceilometers, ALC) provide information on aerosols which can impact urban climate and citizen health. To design an observational network of ALC sensors for supporting data assimilation, and improve prediction of urban weather and air quality, a methodology is needed. In this study, spatio-temporal patterns of aerosol attenuated backscatter coefficient are modelled using Met Office numerical weather prediction (NWP) models at two resolutions, 1.5 km (UKV) and 300 m (London Model, LM), for 28 clear-sky days and nights. Initially, attenuated backscatter coefficient data are analysed using S-mode principal component analysis with VARIMAX rotation. Four to seven empirical orthogonal functions (EOFs) are produced for each model level with common EOFs found across different heights (day and night) for both NWP models. EOFs relate strongly to orography, wind and location of aerosol emissions sources highlighting these as critical controls of attenuated backscatter coefficient spatial variability across the megacity. Urban-rural differences are largest when wind speeds are low and vertical boundary layer dynamics can more effectively distribute near-surface aerosol emissions vertically. In several night-time EOFs, gravity wave features are found for both NWP models. Increasing the horizontal resolution of native ancillaries (model input parameters) and improving the urban surface scheme in the LM may enhance the urban signal in the EOFs. Principal component analysis (PCA) output, with agglomerative Ward cluster analysis (CA), minimises intra-group variance. The UKV and LM CA shape and size results are similar and strongly related to orography. PCA-CA is a simple, but adaptable methodology, allowing close alignment with observation network design goals. Here the CA is used with wind roses to suggest the optimised placement of ALC deployment is one in the city to observe the urban plume, and others surrounding the city, with priority given to cluster size and frequency of upwind advection