Maria Cecilia Galvez

Three-wavelength backscatter measurement of clouds and aerosols using a white light Lidar system

A white light continuum was generated by a self-trapped intense femtosecond laser pulse in atmospheric-pressure rare gas, krypton. The measured broad spectrum of the generated white light ranged from 300 nm to more than 950 nm. This new light source was utilized for the first time to perform three-wavelength backscatter measurement of aerosols and clouds. The time-resolved backscattered light was separated into three channels, 350 nm, 550 nm and 700 nm. Each channel showed strong backscattering from aerosols and clouds up to 2.5 km. Experimental measurement indicates that this novel light source can be used for multiwavelength lidar studies.

Simultaneous three-wavelength depolarization measurements of clouds and aerosols using a coherent white light continuum

Lidar (light detection and ranging) depolarization measurements were performed simultaneously at three wavelengths using a coherent white light continuum. The white light continuum ranging from the ultraviolet to the infrared region was generated by a focused 0.5 TW/100 fs pulse in a krypton gas cell at the atmospheric pressure. The lidar system consisted of three depolarization channels at 450, 550, and 800 nm. The observed depolarization ratios for each wavelength showed differences for clouds. These depolarization features in wavelength are discussed in terms of particle size and shape using T-matrix computations. The depolarization ratios at three wavelengths can be used to infer information on the size of the particles in clouds, assuming an ice crystal shape a priori. Also, the obtained size distributions from the three-wavelength depolarization ratios correspond with the changes in particle size indicated by changes in the Angstrom coefficient obtained by multiwavelength lidar techniques. This stud...

Observation of Asian Dust Aerosols with Depolarization Lidar Using a Coherent White Light Continuum

We performed a lidar observation of Asian dust aerosols for the first time using a white light lidar system. The lidar used in the observation utilized a coherent white light continuum generated in Kr gas as a light source and was used as a three-wavelength Mie-scattering lidar having a depolarization measurement capability at 450, 550, and 800 nm. Lidar depolarization ratios of 0.30?0.70 at 800 nm were measured. These data reveal a higher depolarization ratio than usual (normally almost zero) in the lower troposphere. Thus, the white light lidar can identify Asian dust particles that pose a threat to cross-border pollution in Japan.

Primary education in Vietnam and pupil online engagement

This paper focuses on exploring the disparities in social awareness and use of the Internet between urban and rural school children in the North of Vietnam. Design/methodology/approach: A total of 525 pupils, aged 9 to 11 years old, randomly selected from 7 urban and rural schools, who are Internet users, participated in the study and consented to responding to a questionnaire adapted from an equivalent European Union (EU) study. A comparative statistical analysis of the responses was then carried out, using IBM SPSS v21, which consisted of a descriptive analysis, an identification of personal self-development opportunities, as well as issues related to pupils’ digital prowess and knowledge of Internet use, and Internet safety, including parental engagement in their offspring’s online activities. Findings: The study highlights the fact that children from both the urban and rural regions of the North of Vietnam mostly access to the Internet from home, but with more children in the urbanized areas accessing it at school than their rural counterparts. Although children from the rural areas scored lower on all the Internet indicators, such as digital access and online personal experience and awareness, there was no disparity in awareness of Internet risks between the two sub-samples. It is noteworthy that there was no statistically significant gender difference towards online activities that support self-development. In relation to safe Internet usage, children are likely to seek advice from their parents, rather than through teachers or friends. However, they are not yet provided with an effective safety net while exposing themselves to the digital world. Originality/value: Although the Vietnamese national curriculum on the Computer Science subject does not explicitly cover the use of the Internet and its related aspects, the majority of children who took part in this study claimed to have used the Internet in their learning activities. This emphasises the urgent need for the MoE and educators in the country to not only improve ICT facilities in schools, but also to revise the Computer Science curriculum in order to (a) provide a supportive environment for learning development and (b) collectively advocate the dynamics of Internet use in order to ensure safe access and use by the children.

Air pollution in Bangalore, India: an eight-year trend analysis.

Bangalore is one of Indias fastest growing metropolises and, although benefiting economically due to its fast development, has a rapidly deteriorating environment. This paper provides a critical analysis of the air pollution trend in the city over the period 2006-2013 at six specific locations where measurements have been consistently recorded. It also discusses the potential health implications pertaining to exceeding levels of pollutants where these are applicable. In order to attain informed decisions on the protection of the health of populations from elevated levels of air pollution, an understanding of spatial-temporal variance of air pollutant patterns is necessary. The study highlights the fact that Bangalore and other similar developing cities do not have an adequate number of fixed monitoring stations that could provide a complete coverage of the air pollution levels for the entire city. It is suggested that this can be overcome by using geospatial interpolation techniques that provide a complete coverage of the levels of pollutants, as well as assist in mapping health characteristics of the population, in order to reach evidence-based decisions and target effective interventions.

Data quality issues in the GIS modelling of air pollution and cardiovascular mortality in Bangalore

Cardiovascular disease (CVD) is the worlds number one cause of mortality. Research in recent years has begun to illustrate a significant association between CVD and air pollution. As most of these studies employed traditional statistics, cross-sectional or meta-analysis methods, a study undertaken by the authors was designed to investigate how a geographical information system (GIS) could be used to develop a more efficient spatio-temporal method of analysis than the currently existing methods mainly based on statistical inference. Using Bangalore, India, as a case study, demographic, environmental and CVD mortality data was sought from the city. However, critical deficiencies in the quality of the environmental data and mortality records were identified and quantified. This paper discusses the shortcomings in the quality of mortality data, together with the development of a framework based on WHO guidelines to improve the defects, henceforth considerably improving data quality.

Simultaneous Three-wavelength Depolarization Lidar Using a Coherent White Light Continuum

In this paper, application of white light lidar system for the multi-wavelength depolarization measurement of clouds and aerosols will be presented. The new lidar system consisted of three depolarization channels at 450, 550 and 800 nm. The linear depolarization ratio (delta = S/P) at 450 nm can be seen to increase with increasing cloud depth due to the multiple scattering.