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Sample records for dar es salaam

  1. CHALLENGES OF TOUR OPERATORS : DAR-ES-SALAAM, TANZANIA

    OpenAIRE

    Nkonoki, Symon

    2012-01-01

    This research is commissioned by Development research organization (DROrg). This is a non-governmental organization based in Dar-es-Salaam, Tanzania which is dealing with conducting various scientific researches with an emphasis on promoting economic development in the country. The aim of this research is to study the challenges of tour operators and suggesting the appropriate measures to eradicate such challenges. Quantitative research method is the method which is applied in this thesis...

  2. A Browning process : The case of Dar es Salaam city

    OpenAIRE

    Mng Ong O, Othmar Simtali

    2005-01-01

    The study is about how green spaces and structures of Dar es Salaam city, quantitatively and qualitatively, are browning out. It also tries to explore the different reasons behind the browning tendency, and what it means to the function of the city and to the daily form of life of the inhabitants. Finally there is a discussion about how to counteract the tendency by involving the inhabitants in planning procedures following the communicative approach to planning. The main investigations have ...

  3. Urban agriculture and Anopheles habitats in Dar es Salaam, Tanzania.

    Science.gov (United States)

    Dongus, Stefan; Nyika, Dickson; Kannady, Khadija; Mtasiwa, Deo; Mshinda, Hassan; Gosoniu, Laura; Drescher, Axel W; Fillinger, Ulrike; Tanner, Marcel; Killeen, Gerry F; Castro, Marcia C

    2009-05-01

    A cross-sectional survey of agricultural areas, combined with routinely monitored mosquito larval information, was conducted in urban Dar es Salaam, Tanzania, to investigate how agricultural and geographical features may influence the presence of Anopheles larvae. Data were integrated into a geographical information systems framework, and predictors of the presence of Anopheles larvae in farming areas were assessed using multivariate logistic regression with independent random effects. It was found that more than 5% of the study area (total size 16.8 km2) was used for farming in backyard gardens and larger open spaces. The proportion of habitats containing Anopheles larvae was 1.7 times higher in agricultural areas compared to other areas (95% confidence interval = 1.56-1.92). Significant geographic predictors of the presence of Anopheles larvae in gardens included location in lowland areas, proximity to river, and relatively impermeable soils. Agriculture-related predictors comprised specific seedbed types, mid-sized gardens, irrigation by wells, as well as cultivation of sugar cane or leafy vegetables. Negative predictors included small garden size, irrigation by tap water, rainfed production and cultivation of leguminous crops or fruit trees. Although there was an increased chance of finding Anopheles larvae in agricultural sites, it was found that breeding sites originated by urban agriculture account for less than a fifth of all breeding sites of malaria vectors in Dar es Salaam. It is suggested that strategies comprising an integrated malaria control effort in malaria-endemic African cities include participatory involvement of farmers by planting shade trees near larval habitats. PMID:19440962

  4. Prospective study of incidence of juvenile diabetes mellitus over 10 years in Dar es Salaam, Tanzania.

    OpenAIRE

    Swai, A. B.; Lutale, J. L.; Mclarty, D. G.

    1993-01-01

    OBJECTIVE--To ascertain the annual incidence of diabetes requiring treatment with insulin in children and adolescents aged 0-19 years in Dar es Salaam, Tanzania, during a 10 year period from 1 January 1982 to 31 December 1991. DESIGN--Prospective registration at a major urban hospital of all patients with newly diagnosed diabetes who were resident in Dar es Salaam. SETTING--Muhimbili Medical Centre, Dar es Salaam, Tanzania. PATIENTS--86 patients: 45 male, 41 female. RESULTS--The annual incide...

  5. Epidemiological Studies on Bovine Mastitis in Smallholder Dairy Herds in the Dar es Salaam Region, Tanzania

    OpenAIRE

    Kivaria, F. M.

    2006-01-01

    Recently the number of milking cows has increased substantially in the Dar es Salaam region due to an increasing demand for fresh milk in this densely populated urban centre. It is estimated that there are 1,765 smallholder dairy herds with 8,233 improved dairy animals in and around the Dar es Salaam region. Urban and peri-urban smallholder dairying is viewed as an agricultural activity that provides a regular and stable income to the household and is considered to be a forerunner of further...

  6. Child Labour in Urban Agriculture: The Case of Dar es Salaam, Tanzania.

    Science.gov (United States)

    Mlozi, Malongo R. S.

    1995-01-01

    Urban agriculture in Dar es Salaam was found to use child labor of both children with parents of higher and lower socioeconomic status (SES). Discusses policy implications and calls for the education of parents of lower SES not to expect an economic contribution from their children's labor, and the education of children about their rights. (LZ)

  7. Towards sustainable ground water management in Dar Es Salaam city, Tanzania

    International Nuclear Information System (INIS)

    Groundwater pollution in urban areas is a worldwide growing environmental problem in this millennium. Many major cities in the world depend on groundwater for water supplies. However, urbanization processes threaten its quality. The problem is more pronounced in urban areas in developing countries like Tanzania, which are characterized with inadequate infrastructure for waste management. In Tanzania, the situation is more threatening in Dar Es Salaam City, which experiences acute deficiency in infrastructure provision: housing, water supply, sanitation, transportation and energy. The existing challenge is to protect groundwater resources amidst rapid growing Dar Es Salaam city, of which failure can lead to escalating costs for provision of drinking water with overall results of decreased public health conditions. A research conducted from 1997 to 2002, revealed that almost 50% of the water supply in Dar Es Salaam city comes from groundwater and that groundwater is being threatened by indiscriminate disposal practices of both domestic and industrial wastes. For example about 88% of the urban population use on-site sanitation systems, which discharge partially treated sewage to the groundwater. About 60 tonnes/day of chemical oxygen demand (COD) are transported to the groundwater through domestic sewage. Analysis of groundwater quality in the city indicated that the unconfined aquifer is starting to degrade. For instance, more than 40% of groundwater samples analysed fohan 40% of groundwater samples analysed for nitrate, chloride and faecal coliform bacteria, did not comply with the national standards for drinking water. Recognising the fact that demand for groundwater is on the increase in the city and that the aquifers have shown signs of degradation, a groundwater management plan is required to ensure sustainable utilization of the resource. This paper discusses the groundwater situation in Dar Es Salaam city and finally puts forward measures towards establishment of a management strategy. (author)

  8. A Review of Traffic Congestion in Dar es Salaam City from the Physical Planning Perspective

    OpenAIRE

    Kiunsi, Robert B.

    2013-01-01

    Traffic congestion is one of the major problems facing Dar es Salaam City and is attributed by a number of factors including rapid population increase, inadequate and poor road infrastructure, city structure, rapid increase in number of cars and lack of physical plan to control city development. The city is already implementing a number of strategies in order to minimize traffic congestion. However, many of the strategies are focusing on improving the capacity of roads in terms of increasing ...

  9. IINFORMAL LABOUR MARKET IN TANZANIA : A case of Kinondoni district in Dar es Salaam

    OpenAIRE

    Setebe, Juliet

    2011-01-01

    ABSTRACT Juliet Manzala Setebe. Informal Labor Market in Tanzania: A case of Kinondoni District in Dar es Salaam. Jarvenpaa Autumn 2011, 48p., 2 appendices . Diaconia University of Applied Sciences, Diak South, Jarvenpaa Unit, Degree Program in Social Services (DSS). Informal Labor Market is a concept that has been researched for more than twenty years, but no one has come up with a concrete definition. Many researchers referred to it as activities which are done outside the governm...

  10. Assessing urban fire risk in the central business district of Dar es Salaam, Tanzania

    OpenAIRE

    Yohannes Kachenje; Jacob Kihila; Huba Nguluma

    2010-01-01

    Buildings as infrastructure along with people’s lives need protection against fire outbreaks. Knowledge on the use of installed facilities is essential in tackling There emergencies, otherwise their installation becomes meaningless. Lack of such knowledge could hamper escape from There hazards and thwart attempts to contain there outbreaks at their preliminary stage. THis study, carried out in the Central Business District of Dar es Salaam City, assessed urban there risk with respect to pub...

  11. Storage, Collection and Disposal of Kariakoo Market Wastes in Dar Es Salaam, Tanzania

    OpenAIRE

    Yhdego, Michael

    2011-01-01

    In many developing countries, the market is still the most important source of commerce for traders and provisions for the general public. The transmission of disease in the market place involves factors relating to the host, the agent and the environment. This study examines the quality of solid waste management in Kariakoo market, Dar es Salaam. The main problems identified were poor market design and lack of a well organized waste storage, collection and disposal systems. Two-thirds of the...

  12. A Review of Traffic Congestion in Dar es Salaam City from the Physical Planning Perspective

    Directory of Open Access Journals (Sweden)

    Robert B. Kiunsi

    2013-01-01

    Full Text Available Traffic congestion is one of the major problems facing Dar es Salaam City and is attributed by a number of factors including rapid population increase, inadequate and poor road infrastructure, city structure, rapid increase in number of cars and lack of physical plan to control city development. The city is already implementing a number of strategies in order to minimize traffic congestion. However, many of the strategies are focusing on improving the capacity of roads in terms of increasing number of lanes, proposing new overpasses and underpasses at the main road intersections and improving public transport. These strategies cannot fully overcome the congestion problems in Dar es Salaam on their own unless efforts are made to redistribute services and community infrastructure. The latter can be achieved through physical planning, which has the potential of influencing trip generation and travel patterns and traffic volume in specific roads. Therefore to minimize traffic congestion in the Dar es Salaam both strategies for improving road capacity, public transport and physical planning solutions ought to be applied together.

  13. Residents’ perceptions of institutional performance in water supply in Dar es Salaam

    Science.gov (United States)

    Mwakalila, Shadrack

    This paper addresses the performance of institutions in water supply systems for improving social and economic benefits of people living in Dar es Salaam city. The methods employed in field data and information collection included interviews, questionnaire, focus group discussions and participatory observation. Kinondoni and Ilala Districts were used as case study. The study revealed that, the main water sources in the study areas are boreholes, shallow wells, rain water and water vendors. Other minor sources are piped water and natural water sources, such as rivers and streams. The supply of piped water by Dar es Salaam Water Sewerage and Sanitation Company (DAWASA/DAWASCO) meets only 45% of the total water demands. Individuals own and sell water from boreholes, shallow wells, piped water connected to their individual houses and natural wells located in their individual plots. The price of one 20 l bucket of water from a water vendor depends on the availability of water and the distance walked from the water source to the customer. Majority of the respondents (77.5%) indicated that individual water delivery systems provide sufficient water as compared to five years ago in the study areas. Few of the respondents (6.3%) said individual water delivery systems have no capacity to provide sufficient water while 16.3% indicate that individual water delivery systems provide moderate water supply but are important in supplementing other water providers in the study areas. The study reveals that a majority of the local population are satisfied with the capacity of individual water delivery systems in providing water for household uses. This paper recommends some improvements to be done to water supply systems in the Dar es Salaam city.

  14. Land for the Dead : Access to and Evolvement of Necral Land in Dar es Salaam, Tanzania

    OpenAIRE

    Eriksson, Pontus

    2010-01-01

    This thesis is aiming to describe and understand the access to and evolvement of necral land (burial and crematory grounds) in Dar es Salaam, the largest city in Tanzania and one of the most rapid growing cities in Africa. The study is based on field work conducted in Kinondoni District during the spring of 2010. It could partly be described as intensive research, because it is done like a pioneer study, trying to describe and understand a phenomena; not so much trying to find out how widespr...

  15. BUS BAY PERFORMANCE AND ITS INFLUENCE ON THE CAPACITY OF ROAD NETWORK IN DAR ES SALAAM

    OpenAIRE

    Mushule, Nurdin K.

    2012-01-01

    One of major problems facing motorists in Dar es Salaam city today is congestion. Bus bays have a significant influence on the capacity of a roadway because they interfere with passing vehicles primarily when buses maneuver to pull into and out of bus bays. Bus bay stops will also interfere with vehicles movement if bus demand exceeds the bus bay capacity resulting in some buses waiting in the travel lane until the buses occupying the bay exit the bay. This paper presents the results of a stu...

  16. Basic analysis of climate and urban bioclimate of Dar es Salaam, Tanzania

    Science.gov (United States)

    Ndetto, Emmanuel L.; Matzarakis, Andreas

    2013-10-01

    Better understanding of urban microclimate and bioclimate of any city is imperative today when the world is constrained by both urbanisation and global climate change. Urbanisation generally triggers changes in land cover and hence influencing the urban local climate. Dar es Salaam city in Tanzania is one of the fast growing cities. Assessment of its urban climate and the human biometeorological conditions was done using the easily available synoptic meteorological data covering the period 2001-2011. In particular, the physiologically equivalent temperature (PET) was calculated using the RayMan software and results reveal that the afternoon period from December to February (DJF season) is relatively the most thermal stressful period to human beings in Dar es Salaam where PET values of above 35 °C were found. Additionally, the diurnal cycle of the individual meteorological elements that influence the PET index were analysed and found that air temperature of 30-35 °C dominate the afternoon period from 12:00 to 15:00 hours local standard time at about 60 % of occurrence. The current results, though considered as preliminary to the ongoing urban climate study in the city, provide an insight on how urban climate research is of significant importance in providing useful climatic information for ensuring quality of life and wellbeing of city dwellers.

  17. Body-Art Practices Among Undergraduate Medical University Students in Dar Es Salaam, Tanzania, 2014

    Science.gov (United States)

    Chacha, Chacha Emmanuel; Kazaura, Method R.

    2015-01-01

    Background: Body-art practices are increasing among adolescents and young adults. Although substantial data are available in developed countries, little has been documented about body-art practices in developing countries. Objective: To determine the magnitude, types and reasons for practicing body-art practices among undergraduate medical University students in Dar es Salaam, Tanzania. Materials and Methods: A cross-sectional descriptive study was conducteed among undergraduate University students in Dar es Salaam involving 536 respondents from two Universities. We used a self-administered questionnaire to collect data. Analyses were based on summary measures and bivariate analyses. Results: While 7.5% of undergraduate students reported having tattoos, 20% reported having body puncturing or piercing. Body piercing is reported more among female university undergraduate students than their male counterparts. Reported main reasons for undergoing body-art include “a mark of beauty,” 24%, “just wanted one,” 18% and “a mark of femininity or masculinity,” 17%. The majority (98%) of students were aware that unsafe body-art practices may lead to contracting HIV and more than half (52%) reported awareness of the risk of Hepatitis B infection. Conclusions: Despite high awareness of the potential risks involved in unsafe body arts that include tattoo and piercing, these practices are increasing among adolescents and young adults. There is need to have educational and counseling efforts so as to minimize associated health risks.

  18. Modeling Urban Growth Spatial Dynamics: Case studies of Addis Ababa and Dar es Salaam

    Science.gov (United States)

    Buchta, Katja; Abo El Wafa, Hany; Printz, Andreas; Pauleit, Stephan

    2013-04-01

    Rapid urbanization, and consequently, the dramatic spatial expansion of mostly informal urban areas increases the vulnerability of African cities to the effects of climate change such as sea level rise, more frequent flooding, droughts and heat waves. The EU FP 7 funded project CLUVA (Climate Change and Urban Vulnerability in Africa, www.cluva.eu) aims to develop strategies for minimizing the risks of natural hazards caused by climate change and to improve the coping capacity of African cities. Green infrastructure may play a particular role in climate change adaptation by providing ecosystem services for flood protection, stormwater retention, heat island moderation and provision of food and fuel wood. In this context, a major challenge is to gain a better understanding of the spatial and temporal dynamics of the cities and how these impact on green infrastructure and hence their vulnerability. Urban growth scenarios for two African cities, namely Addis Ababa, Ethiopia and Dar es Salaam, Tanzania, were developed based on a characterization of their urban morphology. A population growth driven - GIS based - disaggregation modeling approach was applied. Major impact factors influencing the urban dynamics were identified both from literature and interviews with local experts. Location based factors including proximity to road infrastructure and accessibility, and environmental factors including slope, surface and flood risk areas showed a particular impact on urban growth patterns. In Addis Ababa and Dar es Salaam, population density scenarios were modeled comparing two housing development strategies. Results showed that a densification scenario significantly decreases the loss of agricultural and green areas such as forests, bushland and sports grounds. In Dar es Salaam, the scenario of planned new settlements with a population density of max. 350 persons per hectare would lead until 2025 to a loss of agricultural land (-10.1%) and green areas (-6.6%). On the other hand, 12.4% of agricultural land and 16.1% of green areas would be lost in the low density development scenario of unplanned settlements of max. 150 persons per hectare. Relocating the population living in flood prone areas in the case of Addis Ababa and keeping those areas free from further settlements in the case of Dar es Salaam would result in even lower losses (agricultural land: -10.0%, green areas: -5.6%) as some flood prone areas overlap with agricultural/ green areas. The scenario models introduced in this research can be used by planners as tools to understand and manage the different outcomes of distinctive urban development strategies on growth patterns and how they interact with different climate change drivers such as loss of green infrastructure and effects such as frequent flooding hazards. Due to the relative simplicity of their structure and the single modeling environment, the models can be transferred to similar cities with minor modifications accommodating the different conditions of each city. Already, in Addis Ababa the results of the model will be used in the current revision of the Master plan of the city. Keywords: GIS, modeling, Urban Dynamics, Dar es Salaam, Addis Ababa, urbanization

  19. Pit latrine emptying behavior and demand for sanitation services in dar es salaam, Tanzania.

    Science.gov (United States)

    Jenkins, Marion W; Cumming, Oliver; Cairncross, Sandy

    2015-01-01

    Pit latrines are the main form of sanitation in unplanned areas in many rapidly growing developing cities. Understanding demand for pit latrine fecal sludge management (FSM) services in these communities is important for designing demand-responsive sanitation services and policies to improve public health. We examine latrine emptying knowledge, attitudes, behavior, trends and rates of safe/unsafe emptying, and measure demand for a new hygienic latrine emptying service in unplanned communities in Dar Es Salaam (Dar), Tanzania, using data from a cross-sectional survey at 662 residential properties in 35 unplanned sub-wards across Dar, where 97% had pit latrines. A picture emerges of expensive and poor FSM service options for latrine owners, resulting in widespread fecal sludge exposure that is likely to increase unless addressed. Households delay emptying as long as possible, use full pits beyond what is safe, face high costs even for unhygienic emptying, and resort to unsafe practices like 'flooding out'. We measured strong interest in and willingness to pay (WTP) for the new pit emptying service at 96% of residences; 57% were WTP ?U.S. $17 to remove ?200 L of sludge. Emerging policy recommendations for safe FSM in unplanned urban communities in Dar and elsewhere are discussed. PMID:25734790

  20. Planning the unplanned : incorporating agriculture as an urban land use into the Dar es Salaam master plan and beyond

    DEFF Research Database (Denmark)

    Halloran, Afton Marian Szasz; Magid, Jakob

    2013-01-01

    Despite significant contributions to human health, livelihoods and food security, urban agriculture in Dar es Salaam has received relatively little political support from central and local government due to its informal state. As a result, many urban farmers' experience insecurity of land access and ownership, and are unable to invest in the improvement of their land, inputs and infrastructure. Although there have been several attempts by various international and foreign organizations to legitimize and institutionalize urban agriculture in Dar es Salaam, very little has changed politically over the past 30 years. This study focuses on the current incorporation of urban agriculture into the Dar es Salaam 2012-2032 Master Plan (still unapproved as of June 2013), and examines how local and central governments legitimize the practice of urban agriculture. It also looks at how greater acceptance, or institutionalization, can take place through formalized processes. The past and present legitimization processes for urban agriculture in Dar es Salaam, and their intended and unintended outcomes, provide an in-depth analysis for this case study. It argues that the sustainability of urban agriculture is largely dependent on political commitment from both local and central government. Legitimization of the practice through policy and rules and regulations can facilitate the further institutionalization of urban agriculture, especially in land use planning. However, it can also further marginalize urban farmers who cultivate open spaces within the city. Nonetheless, urban agriculture will continue to persist, adapting and innovating under the pressures of urbanization. © 2013 International Institute for Environment and Development (IIED).

  1. Climate change induced risk analysis of Dar es Salaam city (Tanzania)

    Science.gov (United States)

    Topa, Maria Elena; Herslund, Lise; Cavan, Gina; Printz, Andreas; Simonis, Ingo; Bucchignani, Edoardo; Jean-Baptiste, Nathalie; Hellevik, Siri; Johns, Regina; Kibassa, Deusdedit; Kweka, Clara; Magina, Fredrick; Mangula, Alpha; Mbuya, Elinorata; Uhinga, Guido; Kassenga, Gabriel; Kyessi, Alphonce; Shemdoe, Riziki; Kombe, Wilbard

    2013-04-01

    CLUVA (CLimate change and Urban Vulnerability in Africa; http://www.cluva.eu/) is a 3 years project, funded by the European Commission in 2010. The main objective of CLUVA is to develop context-centered methods and knowledge to be applied to African cities to assess vulnerabilities and increase knowledge on managing climate related risks. The project estimates the impacts of climate changes in the next 40 years at urban scale and downscales IPCC climate projections to evaluate specific threats to selected African test cities. These are mainly from floods, sea-level rise, droughts, heat waves, and desertification. The project evaluates and links: social vulnerability; urban green structures and ecosystem services; urban-rural interfaces; vulnerability of urban built environment and lifelines; and related institutional and governance dimensions of adaptation. The multi-scale and multi-disciplinary qualitative, quantitative and probabilistic approach of CLUVA is currently being applied to selected African test cities (Addis Ababa - Ethiopia; Dar es Salaam - Tanzania; Douala - Cameroun; Ouagadougou - Burkina Faso; St. Louis - Senegal). In particular, the poster will present preliminary findings for the Dar es Salaam case study. Dar es Salaam, which is Tanzania's largest coastal city, is exposed to floods, coastal erosion, droughts and heat waves, and highly vulnerable to impacts as a result of ineffective urban planning (about 70% unplanned settlements), poverty and lack of basic infrastructure (e.g. lack of or poor quality storm water drainage systems). Climate change could exacerbate the current situation increasing hazard-exposure alongside the impacts of development pressures which act to increase urban vulnerability for example because of informal (unregulated) urbanization. The CLUVA research team - composed of climate and environmental scientists, risk management experts, urban planners and social scientists from both European and African institutions - has started to produce research outputs suitable for use in evidence-based planning activities in the case study cities through interdisciplinary methods and analysis. Climate change projections at 8 km resolution are ready for regions containing each of the case study cities; a preliminary hazard assessment for floods, droughts and heat waves has been performed, based on historical data; urban morphology and related green structures have been characterized; preliminary findings in social vulnerability provide insights how communities and households can resist and cope with, as well as recover from climate induced hazards; vulnerability of informal settlements to floods has been assessed for a case study area (Suna sub ward) and a GIS based identification of urban residential hotspots to flooding is completed. Furthermore, a set of indicators has been identified and the most relevant for Dar es Salaam has been selected by local stakeholders to identify particular vulnerable high risk areas and communities. An investigation of the existing urban planning and governance system and its interface with climate risks and vulnerability has inter-alia suggested severe institutional deficits including over-centralized institutions for disaster risk management and climate change adaptation. A multi-risk framework considering climate-related hazards, and physical and social fragilities has been set up.

  2. Storage, Collection and Disposal of Kariakoo Market Wastes in Dar Es Salaam, Tanzania

    DEFF Research Database (Denmark)

    Yhdego, Michael

    1992-01-01

    In many developing countries, the market is still the most important source of commerce for traders and provisions for the general public. The transmission of disease in the market place involves factors relating to the host, the agent and the environment. This study examines the quality of solid waste management in Kariakoo market, Dar es Salaam. The main problems identified were poor market design and lack of a well organized waste storage, collection and disposal systems. Two-thirds of the waste consists of vegetable matter. Proposals for improved design of storage and collection facilities are described. Experiments revealed wastes from the market are readily decomposable by composting. A change in the design of covered markets and improvements in waste handling are essential to reduce the potential health hazards in developing countries.

  3. Understanding household behavioral risk factors for diarrheal disease in Dar es Salaam: a photovoice community assessment.

    Science.gov (United States)

    Badowski, Natalie; Castro, Cynthia M; Montgomery, Maggie; Pickering, Amy J; Mamuya, Simon; Davis, Jennifer

    2011-01-01

    Whereas Tanzania has seen considerable improvements in water and sanitation infrastructure over the past 20 years, the country still faces high rates of childhood morbidity from diarrheal diseases. This study utilized a qualitative, cross-sectional, modified Photovoice method to capture daily activities of Dar es Salaam mothers. A total of 127 photographs from 13 households were examined, and 13 interviews were conducted with household mothers. The photographs and interviews revealed insufficient hand washing procedures, unsafe disposal of wastewater, uncovered household drinking water containers, a lack of water treatment prior to consumption, and inappropriate toilets for use by small children. The interviews revealed that mothers were aware and knowledgeable of the risks of certain household practices and understood safer alternatives, yet were restricted by the perceived impracticality and financial constraints to make changes. The results draw attention to the real economic and behavioral challenges faced in reducing the spread of disease. PMID:21969836

  4. Identification of diarrheagenic Escherichia coli isolated from infants and children in Dar es Salaam, Tanzania

    Directory of Open Access Journals (Sweden)

    Matee Mecky I

    2007-08-01

    Full Text Available Abstract Background Relatively few studies have been done in Tanzania to detect and classify diarrheagenic Escherichia coli (DEC strains among children with diarrhea. This study aimed at investigating DEC among children in Dar es Salaam aged less than five years hospitalized due to acute/persistent diarrhea. Methods DEC were isolated from stool samples collected from two hundred and eighty children with acute/persistent diarrhea at Muhimbili National Hospital and Ilala and Mwananyamala Municipal Hospitals in Dar es Salaam. A multiplex PCR system method was used to detect a species specific gene for E.coli and ten different virulence genes for detection of five pathogroups of DEC namely enteroaggregative- (EAEC, enteropathogenic- (EPEC, enterotoxigenic- (ETEC, enteroinvasive- (EIEC and enterohemorghagic- Escherichia coli (EHEC. Results Sixty-four patients (22.9% harbored DEC. Forty-one of them (14.6% were categorized as EAEC. Most of the EAEC (82.9% were classified as typical EAEC possessing the aggR gene, and 92.6% carried the aat gene. Isolates from thirteen patients were EPEC (4.6% and most of these (92.3% were typical EPEC with both eae and bfpA genes. Ten isolates were identified as ETEC (3.6% with only the heat stable toxin; either st1a or st1b but not both. Age wise, EAEC and EPEC were significantly more prevalent among the age group 0–6 months (p stx1 and stx2 and EIEC (ial were not detected in this study group. Conclusion The results show a high proportion of DEC among Tanzanian children with diarrhea, with typical EAEC and typical EPEC predominating. The use of primers for both variants of ST1 (st1a and st1b increased the sensitivity for detection of ETEC strains.

  5. BUS BAY PERFORMANCE AND ITS INFLUENCE ON THE CAPACITY OF ROAD NETWORK IN DAR ES SALAAM

    Directory of Open Access Journals (Sweden)

    Nurdin K. Mushule

    2012-01-01

    Full Text Available One of major problems facing motorists in Dar es Salaam city today is congestion. Bus bays have a significant influence on the capacity of a roadway because they interfere with passing vehicles primarily when buses maneuver to pull into and out of bus bays. Bus bay stops will also interfere with vehicles movement if bus demand exceeds the bus bay capacity resulting in some buses waiting in the travel lane until the buses occupying the bay exit the bay. This paper presents the results of a study which was carried out to evaluate the bus bay performance and its influence on the capacity of the roadway network in the city of Dar es Salaam. The case study area covered 11 bus stops along Morogoro road from Ubungo to Magomeni Mapipa. Capacity of bus bays was studied using procedure outlined in the Transit Capacity and Quality of Service Manual of 2003. This enabled the researcher to determine parameters such as dwell times and clearance times which are major determinants of bus stop capacity. The results indicate that only 18% of the bus bay stops studied did not have adequate capacity to cater for the available demand. 9% did not have adequate capacity during peak hours but the capacity was adequate during off-peak hours. The remaining 73% of bus bay stops possess adequate capacity all the time. Although most bus bay stops studied possess adequate capacity, severe congestion was observed at these locations. This is due to erratic behavior of bus drivers who do not utilize the provided space for them to drop off and pick up passengers. Clearly, this is an area that requires more strict enforcement in order to ease the congestion problem in the city by operating the existing capacity more efficiently."

  6. Rapid Urban Malaria Appraisal (RUMA II: Epidemiology of urban malaria in Dar es Salaam (Tanzania

    Directory of Open Access Journals (Sweden)

    Manane Lusinge

    2006-04-01

    Full Text Available Abstract Background The thinking behind malaria research and control strategies stems largely from experience gained in rural areas and needs to be adapted to the urban environment. Methods A rapid assessment of urban malaria was conducted in Dar es Salaam in June-August, 2003 using a standard Rapid Urban Malaria Appraisal (RUMA methodology. This study was part of a multi-site study in sub-Saharan Africa supported by the Roll Back Malaria Partnership. Results Overall, around one million cases of malaria are reported every year by health facilities. However, school surveys in Dar es Salaam during a dry spell in 2003 showed that the prevalence of malaria parasites was low: 0.8%, 1.4%, 2.7% and 3.7% in the centre, intermediate, periphery and surrounding rural areas, respectively. Health facilities surveys showed that only 37/717 (5.2% of presenting fever cases and 22/781 (2.8% of non-fever cases were positive by blood slide. As a result, malaria-attributable fractions for fever episodes were low in all age groups and there was an important over-reporting of malaria cases. Increased malarial infection rates were seen in persons who travelled to rural areas within the past three months. A remarkably high coverage of insecticide-treated nets and a corresponding reduction in malarial infection risk were found. Conclusion The number of clinical malaria cases was much lower than routine reporting suggested. Improved malaria diagnosis and re-defined clinical guidelines are urgently required to avoid over-treatment with antimalarials.

  7. Risk factors for sexually transmitted diseases among women attending family planning clinics in Dar-es-Salaam, Tanzania.

    OpenAIRE

    Gertig, D. M.; Kapiga, S. H.; Shao, J. F.; Hunter, D. J.

    1997-01-01

    BACKGROUND: Identification of risk factors for sexually transmitted diseases (STDs) assists in development of treatment algorithms, which are potentially important components of STD control when microbiologic facilities are limited. METHODS: A cross-sectional study was performed to assess STD and HIV risk factors of 2285 women attending three family planning clinics in Dar-es-Salaam, Tanzania during 1991-92. Women were interviewed and examined for signs of STDs. Specimens were taken for labor...

  8. Efficacy of Waterless Hand Hygiene Compared with Handwashing with Soap: A Field Study in Dar es Salaam, Tanzania

    OpenAIRE

    Pickering, Amy J.; Boehm, Alexandria B.; Mwanjali, Mathew; Davis, Jennifer

    2010-01-01

    Effective handwashing with soap requires reliable access to water supplies. However, more than three billion persons do not have household-level access to piped water. This research addresses the challenge of improving hand hygiene within water-constrained environments. The antimicrobial efficacy of alcohol-based hand sanitizer, a waterless hand hygiene product, was evaluated and compared with handwashing with soap and water in field conditions in Dar es Salaam, Tanzania. Hand sanitizer use b...

  9. Air pollution by motor traffic in Dar-es-Salaam. Measurements and state of the art description

    Energy Technology Data Exchange (ETDEWEB)

    Henricson, Daniel

    1999-06-01

    Dar-es-Salaam was the capital of Tanzania until 1973, when it was moved to Dodoma. The city is still the largest and holds about 1.6 million inhabitants. The aim of the project is to measure air pollution from traffic close to people and set a foundation for future studies. Besides that finding ways to reduce air pollution and improve traffic situation in Dar-es-Salaam with an emphasis on the central city parts. Previous studies on air pollution in Dar-es-Salaam have all been rather rushed and mostly with old and not very precise equipment. For that reason you could say this project is like a pilot study. Measurements were made on NO, NO{sub 2}, SO{sub 2}, O{sub 3}, and VOC (hydrocarbons) during two different measuring weeks. Average temperature, wind velocity and traffic flow was measured on both weeks. Traffic flow was 12 000 vehicles/day. The percentage of accelerating/retarding vehicles and average speed was also studied. Average speed was 20 km/h. The result above show levels somewhat exceeding the guidelines. The levels can not be said to be alarmingly high, but bearing the rapid increase in the number of vehicles in mind, air pollution will soon be a major problem. It would have been preferred to also measure lead, particles and carbon monoxide, especially particles since previous reports indicates very high levels. To create a better air quality in Dar-es-Salaam there has to be an improvement of public transport and at the same time increased parking fees and fuel prices. Finally, fuel quality has to improve and unleaded petrol has to be introduced as soon as possible 10 refs, 4 figs, 15 tabs

  10. Exploring social-cultural explanations for residential location choices : the case of an African City - Dar es Salaam

    OpenAIRE

    Limbumba, Tatu Mtwangi

    2010-01-01

    This study explores the factors urban residents consider when making residential location decisions. The context of the study is informal residential areas in a rapidly urbanising African city – the city of Dar es Salaam in Tanzania. A central concern in the study is how the urban poor make their residential location decisions; the assumption is that with income limitations the urban poor rely on other non-economic resources to enable their residential location decisions in the context of r...

  11. Obesity, Overweight, and Perceptions about Body Weight among Middle-Aged Adults in Dar es Salaam, Tanzania

    OpenAIRE

    Muhihi, Alfa J.; Njelekela, Marina A.; Rose Mpembeni; Mwiru, Ramadhani S.; Nuru Mligiliche; Jacob Mtabaji

    2012-01-01

    Background. Prevalence of obesity is increasing throughout the world at an alarming rate. Appropriate perception of one's own body weight is important for improved weight control behavior. This study was conducted to determine the prevalence of overweight and obesity and assess perception of body weight among middle aged adults in Dar es Salaam, Tanzania. Methods. Structured questionnaire was used to collect sociodemographic and lifestyle information including perception about body weight. An...

  12. Resettling Displaced Residents from Regularized Settlements in Dar es Salaam City, Tanzania : The case of Community Infrastructure Upgrading Program (CIUP)

    OpenAIRE

    Magembe-mushi, Dawah Lulu

    2011-01-01

    This research seeks to examine the process of displacement and resettlement of residents who had been affected by regularization process within Manzese and Buguruni wards in Dar es Salaam City, Tanzania. It aimed at analyzing the issues and opportunities faced by the affected residents during regularization. The regularization which involves two processes, tenure and physical upgrading has been extensively used in solving problems associated with unplanned and informal settlements within deve...

  13. The changing nature of the Peri-Urban Zone in Africa: evidence from Dar-es-Salaam,Tanzania

    OpenAIRE

    Briggs, J. A.; Mwamfupe, D.

    1999-01-01

    Research on the peri-urban zones of African cities since the mid-1980s has focused around three main themes, these being peri-urban agriculture as a survival strategy, debates about the relative efficiencies of peri-urban agriculture, and the question of production priorities. Drawing on recent evidence from Dar-es-Salaam in Tanzania, this paper suggest that a combination of structural adjustment measures and the eased economic crisis in Tanzania has changed conditions, the result of which ha...

  14. Acceptance of contraceptives among women who had an unsafe abortion in Dar es Salaam

    DEFF Research Database (Denmark)

    Rasch, Vibeke; Massawe, Siriel

    2004-01-01

    OBJECTIVE: To assess the need for post-abortion contraception and to determine if women who had an unsafe abortion will use a contraceptive method to avoid repeated unwanted pregnancies and STDs/HIV. METHOD: Women attending Temeke Municipal Hospital, Dar es Salaam, after an unsafe abortion or an induced abortion performed at the hospital (n=788) were counselled about contraception and the risk of contracting STDs/HIV. A free ward-based contraceptive service was offered and the women were asked to return for follow-up. RESULTS: Participants (90%) accepted the post-abortion contraceptive service. Of these, 86% stated they were still using contraception 1-6 months after discharge. Initially, 55% of the women accepted to use condoms either alone or as part of double protection. After 1-6 months this proportion had dropped to 18%. Single women were significantly more likely to use condoms. CONCLUSION: High-quality contraceptive service counselling can induce women to use contraception after having had an unsafe abortion. The results of our study are encouraging and should be used to convince policy makers of the need to implement such services at municipal level to reduce the number of repeated unsafe abortions.

  15. The role of local government in promoting sustainable urban agriculture in Dar es Salaam and Copenhagen

    DEFF Research Database (Denmark)

    Halloran, Afton Marian Szasz; Magid, Jakob

    2013-01-01

    As a multifunctional activity and land use, urban agriculture supports a range of objectives, from urban greening to food security. However, it is often left out of urban policy. As a result of the highly contextual and cross-cutting nature of urban agriculture, there are relatively few comprehensive and formalized regulatory tools to draw from. Different cities around the world are now deciding how to fit urban agriculture into the urban agenda; however, in many places urban agriculture continues to operate in the absence of legitimization due to its relatively mobile and dynamic nature. This article looks at the importance of local and central governments in promoting sustainable urban agriculture. Through participatory action research, it examines the cases of Dar es Salaam, Tanzania and Copenhagen, Denmark to understand stakeholder interactions, as well as present and future barriers to the conservation of existing urban agriculture and future initiatives. The findings suggest that municipal recognition and institutional support for urban agriculture is an important component in increasing the sustainability of related initiatives. Local and central government plays a role in the legitimization and institutionalization of urban agriculture through the facilitation of multi-stakeholder processes, policy development and the conservation and allocation of land. © 2013 Taylor & Francis.

  16. Assessing urban fire risk in the central business district of Dar es Salaam, Tanzania

    Directory of Open Access Journals (Sweden)

    Yohannes Kachenje

    2010-04-01

    Full Text Available Buildings as infrastructure along with people’s lives need protection against fire outbreaks. Knowledge on the use of installed facilities is essential in tackling There emergencies, otherwise their installation becomes meaningless. Lack of such knowledge could hamper escape from There hazards and thwart attempts to contain there outbreaks at their preliminary stage. THis study, carried out in the Central Business District of Dar es Salaam City, assessed urban there risk with respect to public awareness on the use of #re #ghting facilities and preparedness in the event of #re outbreaks. Public buildings with at least four storeys or 2000m2 floor space were surveyed. According to the Fire and Rescue Act of 2007, such buildings have to be provided with adequate means of escape and #re #ghting facilities. Data was collected through observation and interviews with building managers, users and key informants. The study revealed high there disaster risk in most buildings of the study area, as 60% of the buildings’ users do not know how to operate the facilities, and 41% are not aware of the available escape means in case of there outbreak. Worse still, only 29% had received training within the past five years, and 68% had never been trained.

  17. Patient satisfaction with HIV/AIDS care at private clinics in Dar es Salaam, Tanzania.

    Science.gov (United States)

    Miller, James S; Mhalu, Aisa; Chalamilla, Guerino; Siril, Hellen; Kaaya, Silvia; Tito, Justina; Aris, Eric; Hirschhorn, Lisa R

    2014-01-01

    Health system responsiveness (HSR) measures quality of care from the patient's perspective, an important component of ensuring adherence to medication and care among HIV patients. We examined HSR in private clinics serving HIV patients in Dar es Salaam, Tanzania. We surveyed 640 patients, 18 or older receiving care at one of 10 participating clinics, examining socioeconomic factors, HIV regimen, and self-reported experience with access and care at the clinic. Ordered logistic regression, adjusted for clustering of the clinic sites, was used to measure the relationships between age, gender, education, site size, and overall quality of care rating, as well as between the different HSR domains and overall rating. Overall, patients reported high levels of satisfaction with care received. Confidentiality, communication, and respect were particularly highly rated, while timeliness received lower ratings despite relatively short wait times, perhaps indicating high expectations when receiving care at a private clinic. Respect, confidentiality, and promptness were significantly associated with overall rating of health care, while provider skills and communication were not significantly associated. Patients reported that quality of service and confidentiality, rather than convenience of location, were the most important factors in their choice of a clinic. Site size (patient volume) was also positively correlated with patient satisfaction. Our findings suggest that, in the setting of urban private-sector clinics, flexible clinics hours, prompt services, and efforts to improve respect, privacy and confidentiality may prove more helpful in increasing visit adherence than geographic accessibility. While a responsive health system is valuable in its own right, more work is needed to confirm that improvements in HSR in fact lead to improved adherence to care. PMID:24499337

  18. CHARACTERIZATION OF SALMONELLA SPECIES FROM WATER BODIES IN DAR-ES-SALAAM CITY, TANZANIA

    Directory of Open Access Journals (Sweden)

    Eliningaya Kweka

    2013-03-01

    Full Text Available Background: Water-borne diseases are the most common cause of illness and death among the poor population from developing countries. The majority of the people are inadequately aware that aquatic environment is a major source of salmonellosis. Dar es Salaam city is among the cities with most of its population live in squatter. Typhoid fever ranks second with 14.3% of all notifiable disease cases in the city. The city experience water scarcity which forces water wells and rivers to become the main sources of water for domestic use and livestock. This study therefore, characterized Salmonella strains from different water bodies of city as possible sources for enteric diseases endemicity. Methods: The Salmonella Chromogenic Agar (SC Agar and Kligler Iron Agar (KIA media were used for isolation and enumeration of the strains. The inoculated cultures were incubated at 370C for 24 hours. Salmonella colonies were confirmed by magenta colorations and hydrogen sulfide production on SC Agar and KIA Agar, respectively. The Analytical Profile Index 20 Enterobacteriaceae kit (API 20E kit was used to identify Salmonella species. Results: Based on the API 20E kit, the identified Salmonella species from different water bodies were Salmonella ser. paratyphi A (96.9%, Salmonella cholelaesuis spp choleraesuis (99.5% and Salmonella typhi (99.9%. Conclusion: This study shows that shallow wells and rivers which are mainly used by the city dwellers were highly contaminated with Salmonella and were more contaminated than deep wells and marine water bodies. This warrants further investigation on the disease mapping in the urban and peri-urban areas.

  19. Factors for change in maternal and perinatal audit systems in Dar es Salaam hospitals, Tanzania

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    Kisanga Felix

    2010-06-01

    Full Text Available Abstract Background Effective maternal and perinatal audits are associated with improved quality of care and reduction of severe adverse outcome. Although audits at the level of care were formally introduced in Tanzania around 25 years ago, little information is available about their existence, performance, and practical barriers to their implementation. This study assessed the structure, process and impacts of maternal and perinatal death audit systems in clinical practice and presents a detailed account on how they could be improved. Methods A cross sectional descriptive study was conducted in eight major hospitals in Dar es Salaam in January 2009. An in-depth interview guide was used for 29 health managers and members of the audit committees to investigate the existence, structure, process and outcome of such audits in clinical practice. A semi-structured questionnaire was used to interview 30 health care providers in the maternity wards to assess their awareness, attitude and practice towards audit systems. The 2007 institutional pregnancy outcome records were reviewed. Results Overall hospital based maternal mortality ratio was 218/100,000 live births (range: 0 - 385 and perinatal mortality rate was 44/1000 births (range: 17 - 147. Maternal and perinatal audit systems existed only in 4 and 3 hospitals respectively, and key decision makers did not take part in audit committees. Sixty percent of care providers were not aware of even a single action which had ever been implemented in their hospitals because of audit recommendations. There were neither records of the key decision points, action plan, nor regular analysis of the audit reports in any of the facilities where such audit systems existed. Conclusions Maternal and perinatal audit systems in these institutions are poorly established in structure and process; and are less effective to improve the quality of care. Fundamental changes are urgently needed for successful audit systems in these institutions.

  20. Environmental Burden of Charcoal Production and Use in Dar es Salaam, Tanzania

    Directory of Open Access Journals (Sweden)

    Neema Msuya

    2011-12-01

    Full Text Available Tanzanian forests are excessively threatened by increased charcoal production fuelled by increased demand crucially in Dar es Salaam city which consumes nearly 70% of all the charcoal produced in the country. Through use of ecological modeling software STELLA® the environmental burden of charcoal production and use in Tanzania has been established. The study has revealed that the country losses 150,433 ha of forest per year. Due to increase in population by year 2030 almost 2.8 million ha of forests will have been lost. This is equivalent to 8.5% of the total forest cover the country had in 2009. The environmental burden includes air pollution characterized by a total emission of 49, 1.0, and 9.0, 12 million tonnes of CO2, SO2, NOx, and CH4, respectively by 2030. Other adverse impacts include loss of forest cover which ultimately causes degradation of soil quality by increased soil erosion, degradation of water sources and disruption of rainfall pattern including inducing draught. Taking into account that the agriculture in Tanzania is primarily rain fed, this has an adverse impact in agricultural production. In the current exploitation of this important natural resource, its sustainability is severely challenged and the whole concept of the forest being renewable is put into question. From these findings, it is recommended that concrete and deliberate efforts be made to reduce and eventually prohibit the use of charcoal in cities and towns.

  1. Window screening, ceilings and closed eaves as sustainable ways to control malaria in Dar es Salaam, Tanzania

    Directory of Open Access Journals (Sweden)

    Chaki Prosper P

    2009-09-01

    Full Text Available Abstract Background Malaria transmission in Africa occurs predominantly inside houses where the primary vectors prefer to feed. Human preference and investment in blocking of specific entry points for mosquitoes into houses was evaluated and compared with known entry point preferences of the mosquitoes themselves. Methods Cross-sectional household surveys were conducted in urban Dar es Salaam, Tanzania to estimate usage levels of available options for house proofing against mosquito entry, namely window screens, ceilings and blocking of eaves. These surveys also enabled evaluation of household expenditure on screens and ceilings and the motivation behind their installation. Results Over three quarters (82.8% of the 579 houses surveyed in Dar es Salaam had window screens, while almost half (48.9% had ceilings. Prevention of mosquito entry was cited as a reason for installation of window screens and ceilings by 91.4% (394/431 and 55.7% (127/228 of respondents, respectively, but prevention of malaria was rarely cited (4.3%, 22/508. The median cost of window screens was between US $ 21-30 while that of ceilings was between US $301-400. The market value of insecticide-treated nets, window screening and ceilings currently in use in the city was estimated as 2, 5 and 42 million US$. More than three quarters of the respondents that lacked them said it was too expensive to install ceilings (82.2% or window screens (75.5%. Conclusion High coverage and spending on screens and ceilings implies that these techniques are highly acceptable and excellent uptake can be achieved in urban settings like Dar es Salaam. Effective models for promotion and subsidization should be developed and evaluated, particularly for installation of ceilings that prevent entry via the eaves, which are the most important entry point for mosquitoes that cause malaria, a variety of neglected tropical diseases and the nuisance which motivates uptake.

  2. Interdependence of domestic malaria prevention measures and mosquito-human interactions in urban Dar es Salaam, Tanzania

    Directory of Open Access Journals (Sweden)

    Mshinda Hassan

    2007-09-01

    Full Text Available Abstract Background Successful malaria vector control depends on understanding behavioural interactions between mosquitoes and humans, which are highly setting-specific and may have characteristic features in urban environments. Here mosquito biting patterns in Dar es Salaam, Tanzania are examined and the protection against exposure to malaria transmission that is afforded to residents by using an insecticide-treated net (ITN is estimated. Methods Mosquito biting activity over the course of the night was estimated by human landing catch in 216 houses and 1,064 residents were interviewed to determine usage of protection measures and the proportion of each hour of the night spent sleeping indoors, awake indoors, and outdoors. Results Hourly variations in biting activity by members of the Anopheles gambiae complex were consistent with classical reports but the proportion of these vectors caught outdoors in Dar es Salaam was almost double that of rural Tanzania. Overall, ITNs confer less protection against exophagic vectors in Dar es Salaam than in rural southern Tanzania (59% versus 70%. More alarmingly, a biting activity maximum that precedes 10 pm and much lower levels of ITN protection against exposure (38% were observed for Anopheles arabiensis, a vector of modest importance locally, but which predominates transmission in large parts of Africa. Conclusion In a situation of changing mosquito and human behaviour, ITNs may confer lower, but still useful, levels of personal protection which can be complemented by communal transmission suppression at high coverage. Mosquito-proofing houses appeared to be the intervention of choice amongst residents and further options for preventing outdoor transmission include larviciding and environmental management.

  3. Gender differences in diet and nutrition among adults initiating antiretroviral therapy in Dar es Salaam, Tanzania.

    Science.gov (United States)

    Abioye, Ajibola I; Isanaka, Sheila; Liu, Enju; Mwiru, Ramadhani S; Noor, Ramadhani A; Spiegelman, Donna; Mugusi, Ferdinand; Fawzi, Wafaie

    2015-06-01

    Human immunodeficiency virus (HIV)-infected males have poor treatment outcomes after initiation of antiretroviral therapy (ART) compared to HIV-infected women. Dietary factors might mediate the association between sex and disease progression. However, the gender difference in diet among HIV-infected individuals in sub-Saharan Africa is largely unknown. The objective of this study was to examine differences in dietary intake among HIV-infected men and women. We conducted a cross-sectional analysis of dietary questionnaire data from 2038 adults initiating ART in Dar es Salaam, Tanzania to assess whether nutrient adequacy differed by sex. We dichotomized participants' nutrient intakes by whether recommended dietary allowances (RDAs) were met and estimated the relative risk (RR) of meeting RDAs in males using binomial regression models. We also estimated the mean difference in intake of foods and food groups by gender. We found poorer dietary practices among men compared to women. Males were less likely to meet the RDAs for micronutrients critical for slowing disease progression among HIV patients: niacin (RR = 0.39, 95% confidence interval [CI]: 0.27 to 0.55), riboflavin (RR = 0.81, 95% CI: 0.73 to 0.91), vitamin C (RR = 0.94, 95% CI: 0.89 to 1.00), and zinc (RR = 0.06, 95% CI: 0.01 to 0.24). Intake of thiamine, pantothenate, vitamins B6, B12, and E did not vary by gender. Males were less likely to eat cereals (mean difference [servings per day] = -0.21, 95% CI: -0.44 to 0.001) and vegetables (mean difference = -0.47, 95% CI: -0.86 to -0.07) in their diet, but more likely to have meat (mean difference = 0.14, 95% CI: 0.06 to 0.21). We conclude that male HIV patients have poorer dietary practices than females, and this may contribute to faster progression of the disease in males. PMID:25562355

  4. The spectrum of dermatological disorders among primary school children in Dar es Salaam

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    Mgonda Yassin M

    2010-12-01

    Full Text Available Abstract Background Dermatologic disorders are common in many countries but the spectrum varies greatly. Many studies have reported a significant burden of skin diseases in school children. The objective of this study was to determine the current spectrum of dermatological disorders in primary school children in Dar es Salaam city. Methods Primary school children were recruited by multistage sampling. Detailed interview, dermatological examination and appropriate laboratory investigations were performed. Data was analyzed using the 'Statistical Package for Social Sciences' (SPSS program version 10.0 and EPI6. A p-value of Results A total of 420 children were recruited (51% males; mean age 11.4 ± 2.8 years; range 6-19 years. The overall point prevalence of any skin disorder was 57.3% and it was 61.9% and 52.6% in males and females respectively (p = 0.05. Infectious dermatoses accounted for 30.4% with superficial fungal infections (dermatophytoses and pityriasis versicolor being the commonest (20%. Dermatophytoses were diagnosed in 11.4% (48/420; the prevalence in males and females being 12.6% and 10.1% respectively (p = 0.41 and higher (21.8% in the age-group 6-10 years (p = 0.045. Fungal cultures were positive in 42/48 children (88%. All three dermatophyte genera were isolated. Tinea capitis was the commonest disease among culture-positive dermatophytoses (30/42; 71.4% with an overall prevalence of 7.1% (30/420 followed by tinea pedis (11/42; 26.1% whose overall prevalence was 2.6%. Microsporum canis was common in tinea capitis (14/30; 46.7% followed by Trichophyton violaceum (6/30; 20%. Trichophyton rubrum was common in tinea pedis (5/11; 45.5%. Thirty six children (8.6% had pityriasis versicolor which was more prevalent (6/27; 22.l2% in the age group 16-19 years (p = 0.0004. The other common infectious dermatoses were pyodermas (4% and pediculosis capitis (3.6%. Common non-infectious dermatoses were: acne vulgaris (36.4%, non-specific dermatoses (10.7%, non-specific ulcers (5% and atopic eczema (2.6%. Rare conditions (prevalence Conclusions Skin disorders are common in primary school children; infectious dermatoses are still rampant and many children do not seek medical assistance.

  5. Masculine attitudes of superiority deter men from accessing antiretroviral therapy in Dar es Salaam, Tanzania

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    Tumaini M. Nyamhanga

    2013-10-01

    Full Text Available Background: This article presents part of the findings from a larger study that sought to assess the role that gender relations play in influencing equity regarding access and adherence to antiretroviral therapy (ART. Review of the literature has indicated that, in Southern and Eastern Africa, fewer men than women have been accessing ART, and the former start using ART late, after HIV has already been allowed to advance. The main causes for this gender gap have not yet been fully explained. Objective: To explore how masculinity norms limit men's access to ART in Dar es Salaam. Design: This article is based on a qualitative study that involved the use of focus group discussions (FGDs. The study employed a stratified purposive sampling technique to recruit respondents. The study also employed a thematic analysis approach. Results: Overall, the study's findings revealed that men's hesitation to visit the care and treatment clinics signifies the superiority norm of masculinity that requires men to avoid displaying weakness. Since men are the heads of families and have higher social status, they reported feeling embarrassed at having to visit the care and treatment clinics. Specifically, male respondents indicated that going to a care and treatment clinic may raise suspicion about their status of living with HIV, which in turn may compromise their leadership position and cause family instability. Because of this tendency towards ‘hiding’, the few men who register at the public care and treatment clinics do so late, when HIV-related signs and symptoms are already far advanced. Conclusion: This study suggests that the superiority norm of masculinity affects men's access to ART. Societal expectations of a ‘real man’ to be fearless, resilient, and emotionally stable are in direct conflict with expectations of the treatment programme that one has to demonstrate health-promoting behaviour, such as promptness in attending the care and treatment clinic, agreeing to take HIV tests, and disclosing one's status of living with HIV to at least one's spouse or partner. Hence, there is a need for HIV control agencies to design community-based programmes that will stimulate dialogue on the deconstruction of masculinity notions.

  6. Green infrastructure for flood risk management in Dar es Salaam and Copenhagen : exploring the potential for transition towards sustainable urban water management

    DEFF Research Database (Denmark)

    Mguni, Patience; Herslund, Lise Byskov

    2015-01-01

    The risk of flooding in urban areas could be better approached by complementing conventional sewer systems with sustainable urban drainage systems (SUDS) for stormwater management. This may be the case for developing world cities like Dar es Salaam with incomplete sewer services, as well as cities like Copenhagen with fully developed sewer systems. This paper explores some theories relevant to understanding how the implementation of SUDS may be one option for supporting a transition towards sustainable urban water management (SUWM). Using interviews, document analysis and observation, a comparison of the opportunities and barriers for the implementation of SUDS in Dar es Salaam and Copenhagen is presented. The results indicate that a bottom-up approach in Dar es Salaam is important, with the community level taking the lead, while in Copenhagen the top-down approach currently employed is promising. The ability of the institutional frameworks of both cities to support the implementation of SUDS is also discussed.

  7. Urbanization and Its Impacts to Food Systems and Environmental Sustainability in Urban Space: Evidence from Urban Agriculture Livelihoods in Dar es Salaam, Tanzania

    OpenAIRE

    Wakuru Magigi

    2013-01-01

    Urbanisation is the key factor underpinning and catalysing changes in food systems, environmental quality, climate change and agriculture livelihoods in the overall urban ecosystem setting and its sustainability. The paper explores Dar es Salaam, a rapidly expanding city in Sub-Saharan Africa, and shows that urban agriculture provides urban ecosystem services and contributes to environmental sustainability. The interconnections of environmental justice, urban ecosystem ...

  8. Experiences of informal female caregivers providing care for people living with HIV in Dar es Salaam, Tanzania.

    Science.gov (United States)

    Pallangyo, Eunice; Mayers, Pat

    2009-01-01

    This study explored and described the experiences of informal female caregivers providing home-based care to people living with HIV (PLWH) in the Dar es Salaam region, Tanzania. The research design was qualitative, descriptive, and exploratory, and was based on the interpretive paradigm. Study participants provided care at home for family members who were living with HIV at World Health Organization-defined HIV clinical stages III or IV. Semistructured interviews were conducted with eight participants. Transcripts were analyzed using thematic analysis. Themes that emerged were the costs of caring, HIV-related stigma and discrimination, stress and burnout, care burden, and the challenges and support for caregivers. Caregivers of PLWH fulfill an important component of care in developing countries. They provide care that enables PLWH to have some hope, if not of survival, of being cared for with love and dignity. PMID:19887289

  9. Air pollution in southern Africa: The case of motor vehicle exhaust contribution in Dar Es Salaam city

    International Nuclear Information System (INIS)

    The aim of this study was to review air pollution problems in the Southern Africa region and establish the quality of ambient air in Dar Es Salaam city in Tanzania with respect to three vehicular pollutants which are sulphur dioxide (SO2), nitrogen dioxide (NO2) and suspended particulate matters (SPM). These pollutants were measured in eight different locations in Dar-Es Salaam city which are Fire, Morocco, Tazara, Kariakoo, Ubungo, Posta, UCLAS, and Akiba. With the exception of South Africa and Botswana, other countries in the Southern Africa Region which include Tanzania, Mozambique, Malawi. Zambia, Zimbabwe. Angola and Namibia do not have air pollution standards, and regular air pollution monitoring is not carried out in these countries. Diesel fueled vehicles in South Africa are responsible for one third of all smog-forming nitrogen dioxides and almost two-thirds of all particulate pollution emitted by all vehicles. The measurement methods used in Dar Es Salaam study were pararosaniline method for SO2, Saltzman for measuring nitrogen dioxide, and filtration method for suspended particulate matters. The following was observed from the analysis: Hourly sulphur dioxide concentration ranged from 558 -1385 ?g/m3. These measured values were above the recommended WHO guidelines with an hourly objective value of 350 ?g/m3. Hourly nitrogen dioxide concentration was found to range from 18 to 53 ?g/m3. The ge from 18 to 53 ?g/m3. The maximum hourly nitrogen dioxide concentration at 53 ?g/m3 was below the recommended WHO guidelines with a value of 200 ?g/m3. The hourly suspended particulate matter (SPM) was found to range from 744 to 1161 ?g/m3. The measured suspended particulate matter concentrations were above the recommended hourly maximum value by WHO guidelines which is 230?g/m3. The correlation coefficient of pollutants and the number of vehicles counted for different sampling points was determined and found to be fair reasonable with a value of 0.906 for suspended particulate matter (SPM), 0.64 for nitrogen dioxide (NO2) and 0.74 for sulphur dioxide (SO2). Gaussian , model NO2 predictions were comparable to the measured NO2 concentration. The average ratio of model calculated and measured concentrations is 0.60. The correlation coefficient between the measured concentrations and those predicted by the model was found to be 0.6. Remedial measures recommended include development of exhaust pipe emission standards and enforcing them in all countries in the Southern Africa Region. Annual check up of emission levels of SO2 and SPM for motor vehicles is recommended. It is further recommended that imported used vehicles should be tested for emission level prior to their registration, and regular ambient air pollutants levels monitoring activities be introduced in cities and municipalities within the Southern Africa Region for selected gaseous pollutants which should include SO2, NO2, and SPM. (author)

  10. Does Personalized Water and Hand Quality Information Affect Attitudes, Behavior, and Health in Dar es Salaam, Tanzania?

    Science.gov (United States)

    Davis, J.; Pickering, A.; Horak, H.; Boehm, A.

    2008-12-01

    Tanzania (TZ) has one of the highest rates of child mortality due to enteric disease in the world. NGOs and local agencies have introduced numerous technologies (e.g., chlorine tablets, borewells) to increase the quantity and quality of water in Dar es Salaam, the capital of Tanzania, in hopes of reducing morbidity and mortality of waterborne disease. The objective of the present study is to determine if providing personalized information about water quality and hand surface quality, as determined by concentrations of enterococci and E. coli, results in improved health and water quality in households. A cohort study was completed in June-September 2008 in 3 communities ranging from urban to per-urban in Dar es Salaam, Tanzania to achieve our objective. The study consisted of 4 cohorts that were visited 4 times over the 3 month study. One cohort received no information about water and hand quality until the end of the summer, while the other groups received either just information on hand surface quality, just information on water quality, and information on both hand surface and water quality after the first (baseline) household visit. We report concentrations of enterococci and E. coli in water sources (surface waters and bore wells), water stored in households, and environmental waters were children and adults swim and bathe. In addition, we report concentrations of enterococci and E. coli on hands of caregivers and children in households. Preliminary results of surveys on health and perceptions of water quality and illness from the households are provided. Ongoing work will integrate the microbiological and sociological data sets to determine if personalized information interventions resulted in changes in health, water quality in the household, or perceptions of water quality, quantity and relation to human health. Future work will analyze DNA samples from hands and water for human-specific Bacteroides bacteria which are only present in human feces. Our study has the potential to provide empirical evidence to promote large scale monitoring and education campaigns in Africa to improve health and reduce the burden of waterborne disease.

  11. Prevalence of enteropathogenic viruses and molecular characterization of group A rotavirus among children with diarrhea in Dar es Salaam Tanzania

    Directory of Open Access Journals (Sweden)

    Maselle Samwel Y

    2007-12-01

    Full Text Available Abstract Background Different groups of viruses have been shown to be responsible for acute diarrhea among children during their first few years of life. Epidemiological knowledge of viral agents is critical for the development of effective preventive measures, including vaccines. Methods In this study we determined the prevalence of the four major enteropathogenic viruses – rotavirus, norovirus, adenovirus and astrovirus – was determined in 270 stool samples collected from children aged 0 – 60 months who were admitted with diarrhea in four hospitals in Dar es Salaam, Tanzania, using commercially available ELISA kits. In addition, the molecular epidemiology of group A rotavirus was investigated using reverse transcriptase multiplex polymerase chain reaction (RT-PCR. Results At least one viral agent was detected in 87/270 (32.2% of the children. The prevalence of rotavirus, norovirus, adenovirus and astrovirus was 18.1%, 13.7%, 2.6% and 0.4%, respectively. In most cases (62.1% of viruses were detected in children aged 7–12 months. The G and P types (VP7 and VP4 genotypes respectively were further investigated in 49 rotavirus ELISA positive samples. G9 was the predominant G type (81.6%, followed by G1 (10.2% and G3 (0.2%. P[8] was the predominant P type (83.7%, followed by P[6] (0.4% and P[4] (0.2%. The following G and P types were not detected in this study population; G2, G4, G8 G10, P[9], P[10] and P[11]. The dominating G/P combination was G9P[8], accounting for 39 (90.7% of the 43 fully characterized strains. Three (6.1% of the 49 rotavirus strains could not be typed. Conclusion Nearly one third of children with diarrhea admitted to hospitals in Dar es Salaam had one of the four viral agents. The predominance of rotavirus serotype G9 may have implication for rotavirus vaccination in Tanzania.

  12. Current clinical efficacy of chloroquine for the treatment of Plasmodium falciparum infections in urban Dar es Salaam, United Republic of Tanzania.

    OpenAIRE

    Premji, Z.; Makwaya, C.; Minjas, J. N.

    1999-01-01

    Reported is the use of a 14-day WHO protocol, which takes into account the clinical, parasitological and haematological responses to antimalarial drugs, to determine the efficacy of chloroquine in the treatment of uncomplicated malaria in young children (n = 200) in urban Dar es Salaam. Chloroquine failure was found in 43% of the children. Of these, 12.5% were considered to be early treatment failures and were given a single dose of sulfadoxine-pyrimethamine. Fever subsided in all children tr...

  13. INVESTIGATION OF HEAVY METAL POLLUTION AND HEALTH RISKS DUE TO FARMING ACTIVITIES ON A FORMER DUMPSITE IN DAR ES SALAAM, TANZANIA

    OpenAIRE

    Hansson, Caroline; Heiskala, Linnea

    2014-01-01

    The heavy metal pollution from a former solid waste disposal site in Dar es Salaam, Tanzania, that is currently used for urban farming was investigated. The pollution was assessed by measuring the content of copper, lead, zinc and chromium in soil, plants and leachate from the site as well as in the adjacent river. The safe daily intake of onsite cultivated vegetables, in regard to the heavy metal content, was calculated. The analysis showed that there is a health risk connected to consuming ...

  14. Anemia at the Initiation of Tuberculosis Therapy Is Associated with Delayed Sputum Conversion among Pulmonary Tuberculosis Patients in Dar-es-Salaam, Tanzania

    OpenAIRE

    Nagu, Tumaini J.; Spiegelman, Donna; Hertzmark, Ellen; Aboud, Said; Makani, Julie; Matee, Mecky I.; Fawzi, Wafaie; Mugusi, Ferdinand

    2014-01-01

    Background: Pulmonary tuberculosis and anemia are both prevalent in Tanzania. There is limited and inconsistent literature on the association between anemia and sputum conversion following tuberculosis treatment. Methods: Newly diagnosed sputum smear positive pulmonary tuberculosis patients aged ?15 years initiating on standard anti tuberculosis therapy were recruited from 14 of 54 tuberculosis clinics in Dar es Salaam. Patients were receiving medication according to the recommended short c...

  15. Adolescent girls, illegal abortions and "sugar-daddies" in Dar es Salaam: vulnerable victims and active social agents

    DEFF Research Database (Denmark)

    Silberschmidt, Margrethe; Rasch, V

    2001-01-01

    Adolescent girls' early sexual activity, early pregnancy, induced abortions and the increase in HIV infections have become major concerns in Sub-Saharan Africa. Efforts, though, to understand their sexual behaviour and to prevent reproductive health problems are almost non-existent. Adolescent girls are normally seen as victims and easy preys of (often older and married) men's sexual exploitation. This article, which is based on a qualitative study of 51 adolescent girls who had just had an illegal abortion in Dar es Salaam, Tanzania, reveals that these girls are not only victims but also willing preys and active social agents engaging in high-risk sexual behaviour. In order to get material benefits they expose themselves to serious health risks, including induced abortion - without realising their own vulnerability. In our study, one out of four girls had more than one partner at the time they became pregnant, and many counted on an illegally induced abortion if they got pregnant. Even if adolescents are nowallowed free access to family planning information, education and services, our study shows that this remains in the realm of theory rather than practice. Moreover, most adolescent girls are not aware about their right to such services. The paper concludes that the vulnerability of adolescent girls increases without the recognition that sexuality education and contraceptive services do not constitute a licence to practice illicit sex - but rather a means to create more mature and responsible attitudes and to increase sexual and reproductive health.

  16. Capture-recapture analysis of East Coast fever in smallholder dairy herds in the Dar es Salaam region of Tanzania.

    Science.gov (United States)

    Kivaria, F M; Noordhuizen, J P T M

    2010-05-01

    The prevalence of and case fatality rate due to East Coast fever (ECF) were estimated in 1402 dairy cattle in 87 small herds in the Dar es Salaam region of Tanzania, from January 2003 to January 2005 using a capture-recapture method. Information on clinical cases and deaths due to ECF were obtained from farm records and from a questionnaire-based cross-sectional survey conducted between July 2003 and March 2005 as part of longitudinal studies of bovine mastitis in these herds. The number of clinical cases identified was 567 (from farm records) and 496 (from the questionnaire), and the number of deaths recorded were 305 (from farm records) and 251 (from the questionnaire). In all, 450 clinical cases and 191 deaths due to ECF were identified from the two sources, giving an observed prevalence of 32% (CI(95%) 30-35%) and observed case fatality rate of 42% (CI(95%) 38-47%). Following application of the capture-recapture method, the estimated number of clinical cases and deaths was 625 (CI(95%) 617-633) and 401 (CI(95%) 384-418), respectively. The respective prevalence and case fatality rates were 45% (CI(95%) 41-48%) and 64% (CI(95%) 60-68%). The estimates obtained using the capture-recapture method are higher than those identified by traditional cross-sectional studies conducted in the same study area, and probably provide a more accurate epidemiological picture of ECF in this region of Tanzania. PMID:19269202

  17. Urban schistosomiasis and soil transmitted helminthiases in young school children in Dar es Salaam and Tanga, Tanzania, after a decade of anthelminthic intervention

    DEFF Research Database (Denmark)

    Mwakitalu, Mbutolwe E.; Malecela, Mwele N.

    2014-01-01

    Rapid urbanization in resource poor countries often results in expansion of unplanned settlements with overcrowding and inadequate sanitation. These conditions potentially support transmission of schistosomiasis and soil transmitted helminths (STH), but knowledge on the occurrence, transmission and control of these infections in urban settings is limited. The present study assessed the status of urinary schistosomiasis and STH across two different-sized cities in Tanzania - Dar es Salaam and Tanga - after a decade of anthelminthic intervention. Primary school children were examined for parasite eggs in urine and stool. Questionnaires were administered to the children, and observations were made on the urban environments. The burden of urinary schistosomiasis and STH was found to be low in both cities (overall 1.2% in Dar es Salaam and 0.3% in Tanga for urinary schistosomiasis; overall <1% in Dar es Salaam and 1-2% in Tanga for each STH infection), and the identified cases showed no clear pattern of spatial distribution. The findings indicated that a marked decrease in prevalence of these infections had occurred in the two cities during recent years. The observed promising developments appeared to have been accomplished by implementation of drug based intervention programs, in combination with environmental change (fewer snail habitats) and generally improved levels of hygiene. Continued efforts, including anthelminthic treatment and health education, are important to maintain these positive achievements.

  18. Predictors of poor glycemic control in type 2 diabetic patients attending public hospitals in Dar es Salaam

    Directory of Open Access Journals (Sweden)

    Kamuhabwa AR

    2014-10-01

    Full Text Available Appolinary R Kamuhabwa, Emmanuel CharlesUnit of Pharmacology and Therapeutics, School of Pharmacy, Muhimbili University of Health and Allied Sciences, Dar es Salaam, TanzaniaBackground: Tanzania has recently experienced a significant rise in the burden of diabetes, and it is estimated that more than 400,000 people are living with diabetes. A major concern in the management of diabetes is the occurrence of diabetic complications that occur as a result of poor glycemic control. Identification of the factors associated with poor glycemic control is important in order to institute appropriate interventions for the purpose of improving glycemic control and prevention of chronic complications.Aim: The aim of this study was to determine the level of glycemic control and explore the factors associated with poor glycemic control among patients with type 2 diabetes mellitus (T2DM.Methodology: A cross-sectional study was carried out at the diabetic clinics for T2DM patients at the national and municipal hospitals in Dar es Salaam. A total of 469 patients were enrolled over a period of 8 weeks from March 2013 to May 2013. Patients' information such as sociodemographic characteristics, self-care management behaviors, and medication adherence were obtained through interviews. Blood pressure, weight, and height were measured during the day of the interview. All available last readings for fasting blood glucose (FBG measurements, lipid profile, and other clinical characteristics were obtained from patients' records.Results: The mean age of patients was 54.93 years. The majority (63.5% of patients were females and only eight patients had records of lipid profile measurements. Out of 469 patients, 69.7% had FBG of ?7.2 mmol/L, indicating poor glycemic control. Females aged between 40 years and 59 years had significantly higher poor glycemic control (76.1% as compared with their male counterparts. Thirty-eight percent of patients had poor medication adherence, which was associated with poor glycemic control. The proportion of poor glycemic control increased with age. A significantly high proportion of poor glycemic control was observed in patients who had had the disease for more than 20 years since diagnosis. Factors associated with poor glycemic control included lack of health insurance, using more than one oral hypoglycemic agent, normal body mass index, obesity, and nonadherence to diabetic medications.Conclusion: Patients in this study had generally poor glycemic control. From these findings it is recommended that diabetic patients should be routinely screened for lipid profile to determine levels of cholesterol, triglycerides, and low-density lipoproteins, which are risk factors for cardiovascular events. An education program should be developed to educate patients on the importance of medication adherence and weight management for better glycemic control.Keywords: type 2 diabetes, lipid profile, self-management behaviors

  19. Urban biowaste for solid fuel production: waste suitability assessment and experimental carbonization in Dar es Salaam, Tanzania.

    Science.gov (United States)

    Lohri, Christian Riuji; Faraji, Adam; Ephata, Elia; Rajabu, Hassan Mtoro; Zurbrügg, Christian

    2015-02-01

    The poor state of solid waste management in Dar es Salaam (DSM), Tanzania, the large fraction of organic waste generated and a high charcoal consumption by city residents has triggered this research on carbonization of municipal biowaste. Char produced by the thermochemical conversion method of slow pyrolysis can be briquetted and used as cooking fuel alternative to wood-based charcoal. To explore the potential of biowaste carbonization in DSM, the most suitable organic wastes were selected and pyrolyzed in a simple, externally heated carbonization system developed as part of this study. A Multi-Criteria Analysis framework allowed to assess prevailing biowaste types regarding availability and accessibility, and respective suitability in terms of physical-chemical properties. The assessment, using data from a survey and lab analysis, revealed the following biowaste types with highest overall potential for char production in DSM: packaging grass/leaves (PG) used for transportation of fruit and vegetables to the markets, wood waste (WW) from wood workshops, and cardboard (CB) waste. Best practice carbonization of these biowastes in the pyrolyzer showed satisfactory char yields (PG: 38.7%; WW: 36.2%; CB: 35.7% on dry basis). Proximate composition (including volatile, fixed carbon and ash content) and heating value (PG: 20.1 MJ kg(-1); WW: 29.4 MJ kg(-1); CB: 26.7 MJ kg(-1)) of the produced char also compare well with literature data. The energy and emission-related aspects of the system still require further research and optimizations to allow financially viable and safe operation. PMID:25649406

  20. Bacteria isolated from bloodstream infections at a tertiary hospital in Dar es Salaam, Tanzania: antimicrobial resistance of isolates

    Scientific Electronic Library Online (English)

    S, Moyo; S, Aboud; M, Kasubi; S Y, Maselle.

    2010-12-01

    Full Text Available OBJECTIVES: A bloodstream infection (BSI) is a life-threatening condition. We studied the causative agents of BSIs and antimicrobial susceptibility patterns of bacterial isolates at Muhimbili National Hospital (MNH) in Dar es Salaam, Tanzania. METHODS: A retrospective analysis of blood culture resul [...] ts obtained at MNH from January 2005 to December 2009 was done. Blood culture isolates judged to be clinically significant and antimicrobial susceptibility results of the bacteria were included. The frequencies and proportions of bacteria isolated and antimicrobial susceptibility results were analysed and compared using Pearson's chi-square test and Fisher's exact test where applicable, or the Mann-Whitney U-test. RESULTS: A total of 13 833 blood cultures were performed. Bacterial pathogens were detected in 1 855 (13.4%), Gram-positive bacteria (1 523; 82.1%) being significantly more prevalent than Gramnegative bacteria (332; 17.9%) (p=0.008). The most common bacterial pathogens isolated were coagulase-negative staphylococci (CoNS) (1 250; 67.4%), S. aureus (245; 13.2%), Escherichia coli (131; 7%) and Klebsiella spp. (130; 7.0%). All bacteria isolated showed high resistance to penicillin G (70.6%), tetracycline (63.8%), cefotaxime (62.5%) and ampicillin (62.3%). Moderate to high resistance was seen against chloramphenicol (45.2%), erythromycin (35.0%), ciprofloxacin (29.3%), co-trimoxazole (25.0%) and gentamicin (23.5%). Of S. aureus isolates, 23.3% were resistant to methicillin. CONCLUSION: CoNS accounted for two-thirds of the bacterial pathogens isolated. High-level resistance was seen to first-line and inexpensive antimicrobial agents. Routine screening for extendedspectrum beta-lactamase production and methicillin resistance among Gram-negative rods and S. aureus from blood cultures should be instituted to monitor spread of multidrug-resistant isolates.

  1. Community-based environmental management for malaria control: evidence from a small-scale intervention in Dar es Salaam, Tanzania

    Directory of Open Access Journals (Sweden)

    Kannady Khadija

    2009-04-01

    Full Text Available Abstract Background Historically, environmental management has brought important achievements in malaria control and overall improvements of health conditions. Currently, however, implementation is often considered not to be cost-effective. A community-based environmental management for malaria control was conducted in Dar es Salaam between 2005 and 2007. After community sensitization, two drains were cleaned followed by maintenance. This paper assessed the impact of the intervention on community awareness, prevalence of malaria infection, and Anopheles larval presence in drains. Methods A survey was conducted in neighbourhoods adjacent to cleaned drains; for comparison, neighbourhoods adjacent to two drains treated with larvicides and two drains under no intervention were also surveyed. Data routinely collected by the Urban Malaria Control Programme were also used. Diverse impacts were evaluated through comparison of means, odds ratios (OR, logistic regression, and time trends calculated by moving averages. Results Individual awareness of health risks and intervention goals were significantly higher among sensitized neighbourhoods. A reduction in the odds of malaria infection during the post-cleaning period in intervention neighbourhoods was observed when compared to the pre-cleaning period (OR = 0.12, 95% CI 0.05–0.3, p Anopheles larvae indicated a decline in larval density. In the other drain, lack of proper resources and local commitment limited success. Conclusion Although environmental management was historically coordinated by authoritarian/colonial regimes or by industries/corporations, its successful implementation as part of an integrated vector management framework for malaria control under democratic governments can be possible if four conditions are observed: political will and commitment, community sensitization and participation, provision of financial resources for initial cleaning and structural repairs, and inter-sectoral collaboration. Such effort not only is expected to reduce malaria transmission, but has the potential to empower communities, improve health and environmental conditions, and ultimately contribute to poverty alleviation and sustainable development.

  2. Trace metal pollution and its influence on the community structure of soft bottom molluscs in intertidal areas of the Dar es Salaam coast, Tanzania

    International Nuclear Information System (INIS)

    The influence of trace metal pollution on the community structure of soft bottom molluscs was investigated in intertidal areas of the Dar es Salaam coast. Significant enrichment of As, Mn, Mo, Sb, and Zn in sediments was recorded. Redundancy analysis indicated that trace metal pollution contributed 68% of the variation in community structure. Monte Carlo permutation test showed that As and Sb contributed significantly to variation in species composition. T-value biplots and van Dobben circles showed that the gastropods Acteon fortis, Assiminea ovata, and Littoraria aberrans, were negatively affected by As and Sb, while the bivalve Semele radiata and the gastropod Conus litteratus were only negatively affected by As. Bioaccumulation of As, Cd, Cu, Mo and Zn occurred in the bivalve Mactra ovalina and the gastropod Polinices mammilla. This calls for regular monitoring and management measures.

  3. High HIV seroprevalence, rectal STIs and risky sexual behaviour in men who have sex with men in Dar es Salaam and Tanga, Tanzania

    Science.gov (United States)

    Ross, Michael W; Nyoni, Joyce; Ahaneku, Hycienth O; Mbwambo, Jessie; McClelland, R Scott; McCurdy, Sheryl A

    2014-01-01

    Objectives To assess HIV and sexually transmitted infection (STI) prevalence and associated risk factors in men who have sex with men (MSM) in two cities in mainland Tanzania. Methods We conducted respondent-driven sampling of 300 MSM in Dar es Salaam and Tanga. Results In Dar es Salaam, 172 (86%) men (median age 23, IQR 21–28) consented to HIV/STI testing, and 30.2% were HIV seropositive. Only five reported a previous positive HIV test: >90% were new HIV detections. 2.5% were syphilis-exposed and none hepatitis B positive, but 21.4% had a curable STI. Over 90% of the gonorrhoea and chlamydia was rectal. In Tanga, 11.1% of MSM were HIV seropositive, 8% hepatitis B positive and 0% were syphilis-exposed, with 4.4% having a curable STI. Predictors of HIV infection were number of MSM known, city, identifying as gay and having first sex with a man. Predictors for STIs were recent unprotected receptive anal intercourse, and number of MSM seen in the last month. 30% of the sample reported that they sold sex. There was no significant association between HIV and STI infection. Conclusions HIV and STI rates were substantially lower in MSM in a provincial city than in a large metropolis and rates appear to depend on larger numbers of MSM known. Most HIV detected were new cases, and there was a high burden of asymptomatic curable rectal STIs (>1 in 5 MSM). Owing to stigma, MSM may not report homosexuality and thus not have rectal STIs treated. High need for tailored HIV testing and STI screening and treatment of MSM in Tanzania is apparent. PMID:25168042

  4. Adolescent girls with illegally induced abortion in Dar es Salaam: the discrepancy between sexual behaviour and lack of access to contraception

    DEFF Research Database (Denmark)

    Rasch, V; Silberschmidt, Margrethe

    2000-01-01

    This article reports on a study of induced abortion among adolescent girls in Dar es Salaam, Tanzania, who were admitted to a district hospital in Dar es Salaam because of an illegally induced abortion in 1997. In the quantitative part of the study, 197 teenage girls (aged 14-19) were asked for socio-economic details, contraceptive knowledge/use, age at first intercourse and number of sexual partners. In the qualitative part, 51 teenage girls were interviewed in-depth about their relationships with their partners, sexual behaviour, contraceptive use and reasons for non-use, and why they became pregnant. The girls were sexually active at an early age and having sex mainly with men older than themselves. Although most of the girls were in love with and enjoyed sex with their partners, they also entered these relationships to obtain money or gifts in exchange for sex. Most were not using contraception or condoms though they were also at risk of STDs and HIV. These girls were getting pregnant expecting their boyfriends to marry them, or because they did not think they could become pregnant or failed to use contraception correctly. Most adolescent girls are not aware of the 1994 Tanzanian policy that gave them the right to seek family planning services and in practice these services are not being provided. There is a need for youth-friendly family planning services and to make abortion safe and legal, in order to reduce unwanted pregnancies and abortion-related complications and deaths among adolescent girls.

  5. Participatory mapping of target areas to enable operational larval source management to suppress malaria vector mosquitoes in Dar es Salaam, Tanzania

    Directory of Open Access Journals (Sweden)

    Dongus Stefan

    2007-09-01

    Full Text Available Abstract Background Half of the population of Africa will soon live in towns and cities where it can be protected from malaria by controlling aquatic stages of mosquitoes. Rigorous but affordable and scaleable methods for mapping and managing mosquito habitats are required to enable effective larval control in urban Africa. Methods A simple community-based mapping procedure that requires no electronic devices in the field was developed to facilitate routine larval surveillance in Dar es Salaam, Tanzania. The mapping procedure included (1 community-based development of sketch maps and (2 verification of sketch maps through technical teams using laminated aerial photographs in the field which were later digitized and analysed using Geographical Information Systems (GIS. Results Three urban wards of Dar es Salaam were comprehensively mapped, covering an area of 16.8 km2. Over thirty percent of this area were not included in preliminary community-based sketch mapping, mostly because they were areas that do not appear on local government residential lists. The use of aerial photographs and basic GIS allowed rapid identification and inclusion of these key areas, as well as more equal distribution of the workload of malaria control field staff. Conclusion The procedure developed enables complete coverage of targeted areas with larval control through comprehensive spatial coverage with community-derived sketch maps. The procedure is practical, affordable, and requires minimal technical skills. This approach can be readily integrated into malaria vector control programmes, scaled up to towns and cities all over Tanzania and adapted to urban settings elsewhere in Africa.

  6. Organic liquids storage tanks volatile organic compounds (VOCS) emissions dispersion and risk assessment in developing countries: the case of Dar-es-Salaam City, Tanzania.

    Science.gov (United States)

    Jackson, Msafiri M

    2006-05-01

    The emission estimation of nine volatile organic compounds (VOCs) from eight organic liquids storage tanks companies in Dar-es-Salaam City Tanzania has been done by using US EPA standard regulatory storage tanks emission model (TANKS 4.9b). Total VOCs atmospheric emission has been established to be 853.20 metric tones/yr. It has been established further that petrol storage tanks contribute about 87% of total VOCs emitted, while tanks for other refined products and crude oil were emitting 10% and 3% of VOCs respectively. Of the eight sources (companies), the highest emission value from a single source was 233,222.94 kg/yr and the lowest single source emission value was 6881.87 kg/yr. The total VOCs emissions estimated for each of the eight sources were found to be higher than the standard level of 40,000 kg/yr per source for minor source according to US EPA except for two sources, which were emitting VOCs below the standard level. The annual emissions per single source for each of the VOCs were found to be below the US EPA emissions standard which is 2,000 kg/yr in all companies except the emission of hexane from company F1 which was slightly higher than the standard. The type of tanks used seems to significantly influence the emission rate. Vertical fixed roof tanks (VFRT) emit a lot more than externally floating roof tanks (EFRT) and internally floating roof tanks (IFRT). The use of IFRT and EFRT should be encouraged especially for storage of petrol which had highest atmospheric emission contribution. Model predicted atmospheric emissions are less than annual losses measured by companies in all the eight sources. It is possible that there are other routes for losses beside atmospheric emissions. It is therefore important that waste reduction efforts in these companies are directed not only to reducing atmospheric emissions, but also prevention of the spillage and leakage of stored liquid and curbing of the frequently reported illegal siphoning of stored products. Emission rates for benzene, toluene, and xylene were used as input to CALPUFF air dispersion model for the calculation of spatial downwind concentrations from area sources. By using global positioning system (GPS) and geographical information system (GIS) the spatial benzene concentration contributed by organic liquid storage tanks has been mapped for Dar-es-Salaam City. Highest concentrations for all the three toxic pollutants were observed at Kigamboni area, possibly because the area is located at the wind prevailing direction from the locations of the storage tanks. The model predicted concentrations downwind from the sources were below tolerable concentrations by WHO and US-OSHA. The highest 24 hrs averaging time benzene concentration was used for risk assessment in order to determine maximum carcinogenic risk amongst the population exposed at downwind. Established risk for adult and children at 2.9x10(-3) and 1.9x10(-3) respectively, are higher than the acceptable US-EPA risk of 1x10(-6). It is very likely that the actual VOCs concentrations in some urban areas in Tanzania including Dar-es-Salaam City are much higher than the levels reported in this study when other sources such as petrol stations and motor vehicles on the roads are considered. Tanzania Government therefore need to put in place: an air quality policy and legislation, establish air quality guidelines and acquire facilities which will enable the implementation of air quality monitoring and management programmes. PMID:16779602

  7. Towards a holistic perspective on city-level vulnerability assessment : A multidimensional approach to a spatial MCE using GIS in Dar es Salaam

    DEFF Research Database (Denmark)

    Karlsson Nyed, Patrik; Herslund, Lise Byskov

    2014-01-01

    The deliverable introduces a map of the vulnerability to flooding in Dar es Salaam at the resolution of the finest administrative level (the subward/mtaa; comprising approx. 5-15 000 residents). Overlaying a hydrological model, representing the areas of the city most likely to become flooded, the high-risk areas may be identified. That is, where the flood-prone areas coincide with the highly vulnerable subwards. The deliverable explores in a step-by-step manner how to capture, measure and process spatial data of multiple dimensions and integrating them into a Geographical Information System (GIS). The overall approach is a spatial multiple criteria evaluation (S-MCE) process, following a series of steps, whereby the most important multi-dimensional indicators of vulnerability to flooding are selected, measured and analyzed. Eventually the output is presented as a product in one, aggregated dimension, easy to comprehend for policy- and decision-makers. The deliverable also presents how the stakeholders of acity are introduced to this process at an early stage, and how they as an expertise group, are providing with vital information and insight, that give the study relevance and are facilitating the subsequent steps of the methodology. The preceding Deliverable 3.3 compiled a comprehensive list of relevant indicators of vulnerability to flooding. This deliverable (D3.4) takes off from there with the selection and weighting of indicators by the stakeholders. Subsequently the stakeholders provide valuable input to (proxy) variables to the indicators and how they may be measured. An important conclusion from these participatory processes is that the selected set of most important vulnerability indicators is highly distinct in space (site-specific). The stakeholder interactions in Dar es Salaam and Addis Ababa show that the selected indicators are only partially overlapping, which would discourage from generating a common subset of indicators for all flood-prone cities. Taking the standpoint in the multi-dimensional setup (a conceptual framework developed by CLUVA Task 2.3), the deliverable presents ample examples of how to work with indicators spatially. Detailed introductions are given to how the more GIS-related indicators, like mobility and low-lying areas, as well as the more intangible indicators, like institutional capacity and trust, may be measured and mapped. However, taking on the task of an S-MCE approach in a developing country also reveals its limitations. The methodology here was developed with the comprehension that the data availability and accessibility might be limited. Consequently, there was a hope that the bulk of the input data would be already available at project start – generated from conventional GIS procedures and originated from routine data collection techniques. However, later in the project it turned out that some parts of the data supply was insufficient, and that alternative sources had to be consulted, which initiated a lengthy and difficult process of data accessibility. The finalvulnerability map for Dar es Salaam is indicating that vulnerability is strongly associated with the informal residential areas (characteristically the unplanned settlements), but the relationship is not fully conclusive. Thus, there are examples of densely populated low-income residential areas where the vulnerability not necessarily is high. Taking the flood-prone areas into account shows that the main high-risk areas (subwards) are located to the west of the city center. Yet again, looking at the individual vulnerability indicators, they reveal that there is no common subset of indicators explaining the vulnerability of the subwards in the high-risk areas. Consequently, the indicators relating to high vulnerability of one subward in the high-risk area, may not be the same in a nearby subward in the same flood-prone area. Furthermore, there is a distinction between the vulnerable subwards in the peripheral areas compared to them closer to the city center. Among the subwards in the outskirts of the city the vulne

  8. Ready to Use Therapeutic Foods (RUTF improves undernutrition among ART-treated, HIV-positive children in Dar es Salaam, Tanzania

    Directory of Open Access Journals (Sweden)

    Sunguya Bruno F

    2012-08-01

    Full Text Available Abstract Background HIV/AIDS is associated with an increased burden of undernutrition among children even under antiretroviral therapy (ART. To treat undernutrition, WHO endorsed the use of Ready to Use Therapeutic Foods (RUTF that can reduce case fatality and undernutrition among ART-naïve HIV-positive children. However, its effects are not studied among ART-treated, HIV-positive children. Therefore, we examined the association between RUTF use with underweight, wasting, and stunting statuses among ART-treated HIV-positive children in Dar es Salaam, Tanzania. Methods This cross-sectional study was conducted from September-October 2010. The target population was 219 ART-treated, HIV-positive children and the same number of their caregivers. We used questionnaires to measure socio-economic factors, food security, RUTF-use, and ART-duration. Our outcome variables were underweight, wasting, and stunting statuses. Results Of 219 ART-treated, HIV-positive children, 140 (63.9% had received RUTF intervention prior to the interview. The percentages of underweight and wasting among non-RUTF-receivers were 12.4% and 16.5%; whereas those of RUTF-receivers were 3.0% (P?=?0.006 and 2.8% (P?=?0.001, respectively. RUTF-receivers were less likely to have underweight (Adjusted Odd Ratio (AOR =0.19, CI: 0.04, 0.78, and wasting (AOR?=?0.24, CI: 0.07, 0.81, compared to non RUTF-receivers. Among RUTF receivers, children treated for at least four months (n?=?84 were less likely to have underweight (P?=?0.049, wasting (P?=?0.049 and stunting (P? Conclusions Among HIV-positive children under ART, the provision of RUTF for at least four months was associated with low proportions of undernutrition status. RUTF has a potential to improve undernutrition among HIV-positive children under ART in the clinical settings in Dar es Salaam, Tanzania.

  9. Improved quality of management of eclampsia patients through criteria based audit at Muhimbili National Hospital, Dar es Salaam, Tanzania. Bridging the quality gap

    Directory of Open Access Journals (Sweden)

    Kidanto Hussein

    2012-11-01

    Full Text Available Abstract Background Criteria-based audits (CBA have been used to improve clinical management in developed countries, but have only recently been introduced in the developing world. This study discusses the use of a CBA to improve quality of care among eclampsia patients admitted at a University teaching hospital in Dar es Salaam Tanzania. Objective The prevalence of eclampsia in MNH is high (?6% with the majority of cases arriving after start of convulsions. In 2004–2005 the case-fatality rate in eclampsia was 5.1% of all pregnant women admitted for delivery (MNH obstetric data base. A criteria-based audit (CBA was used to evaluate the quality of care for eclamptic mothers admitted at Muhimbili National Hospital (MNH, Dar es Salaam, Tanzania after implementation of recommendations of a previous audit. Methods A CBA of eclampsia cases was conducted at MNH. Management practices were evaluated using evidence-based criteria for appropriate care. The Ministry of Health (MOH guidelines, local management guidelines, the WHO manual supplemented by the WHO Reproductive Health Library, standard textbooks, the Cochrane database and reviews in peer reviewed journals were adopted. At the initial audit in 2006, 389 case notes were assessed and compared with the standards, gaps were identified, recommendations made followed by implementation. A re-audit of 88 cases was conducted in 2009 and compared with the initial audit. Results There was significant improvement in quality of patient management and outcome between the initial and re-audit: Review of management plan by senior staff (76% vs. 99%; P=0.001, urine for albumin test (61% vs. 99%; P=0.001, proper use of partogram to monitor labour (75% vs. 95%; P=0.003, treatment with steroids for lung maturity (2.0% vs. 24%; P=0.001, Caesarean section within 2 hours of decision (33% vs. 61%; P=0.005, full blood count (28% vs. 93%; P=0.001, serum urea and creatinine (44% vs. 86%; P=0.001, liver enzymes (4.0% vs. 86%; P=0.001, and specialist review within 2 hours of admission (25% vs. 39%; P=0.018. However, there was no significant change in terms of delivery within 24 hours of admission (69% vs. 63%; P=0.33. There was significant reduction of maternal deaths (7.7% vs. 0%; P=0.001. Conclusion CBA is applicable in low resource setting and can help to improve quality of care in obstetrics including management of pre-eclampsia and eclampsia.

  10. Red blood cell indices and prevalence of hemoglobinopathies and glucose 6 phosphate dehydrogenase deficiencies in male Tanzanian residents of Dar es Salaam.

    Science.gov (United States)

    Mwakasungula, Solomon; Schindler, Tobias; Jongo, Said; Moreno, Elena; Kamaka, Kasimu; Mohammed, Mgeni; Joseph, Selina; Rashid, Ramla; Athuman, Thabit; Tumbo, Anneth Mwasi; Hamad, Ali; Lweno, Omar; Tanner, Marcel; Shekalaghe, Seif; Daubenberger, Claudia A

    2014-01-01

    Hemoglobinopathies, disorders of hemoglobin structure and production, are one of the most common monogenic disorders in humans. Glucose 6 phosphate dehydrogenase deficiency (G6PD) is an inherited enzymopathy resulting in increased oxygen stress susceptibility of red blood cells. The distributions of these genetic traits in populations living in tropical and subtropical regions where malaria has been or is still present are thought to result from survival advantage against severe life threatening malaria disease. 384 male Tanzanian volunteers residing in Dar es Salaam were typed for G6PD, sickle cell disease and ?-thalassemia. The most prominent red blood cell polymorphism was heterozygous ?(+)-thalassemia (37.8%), followed by the G6PD(A) deficiency (16.4%), heterozygous sickle cell trait (15.9%), G6PD(A-) deficiency (13.5%) and homozygous ?(+)-thalassemia (5.2%). 35%, 45%, 17% and 3% of these volunteers were carriers of wild type gene loci, one, two or three of these hemoglobinopathies, respectively. We find that using a cut off value of 28.6 pg. for mean corpuscular hemoglobin (MCH), heterozygous ?(+)-thalassemia can be predicted with a sensitivity of 84% and specificity of 72% in this male population. All subjects carrying homozygous ?(+)-thalassemia were identified based on their MCH value < 28.6 pg. PMID:25755846

  11. A retrospective study of the aetiology and temporal distribution of bovine clinical mastitis in smallholder dairy herds in the Dar es Salaam region of Tanzania.

    Science.gov (United States)

    Kivaria, F M; Noordhuizen, J P T M

    2007-05-01

    A 31-year record-based retrospective study was carried out to determine the aetiology and temporal distribution of bovine clinical mastitis in smallholder dairy herds in the Dar es Salaam region of Tanzania over the period November 1971-December 2002. Laboratory information on 1964 quarter samples from 1365 cows in 281 smallholder dairy herds were retrieved, compiled and studied. Eighty-eight percent of the quarter samples were culture-positive and the predominant mastitis pathogens isolated were Staphylococcus aureus (25.7%), Streptococcus agalactiae (15.4%), Klebsiella pneumoniae (14.3%) and Escherichia coli (14.1%). Other isolates included Pseudomonas aeruginosa (7.5%), Streptococcus dysgalactiae (5.2%) and Streptococcus uberis (4.2%). Contagious mastitis pathogens were isolated from 45.6% of the culture-positive samples, whereas environmental and miscellaneous pathogens were isolated from 48.2% and 5.7%, respectively. Thirty percent of the miscellaneous mastitis pathogens were Candida species. The results demonstrate a steady increase in clinical Candida albicans mastitis. The prevalence of Candida albicans has increased from 1% in 1971 to 17.0% in November 2002. Conversely, despite some fluctuations, the prevalence of Staphylococcus aureus, Streptococcus agalactiae, E. coli and K. pneumoniae remain above 10%. The possible risk factors for these observations are discussed. PMID:16516507

  12. Detection of pulmonary tuberculosis among patients with cough attending outpatient departments in Dar Es Salaam, Tanzania: does duration of cough matter?

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    Wandwalo Eliud R

    2009-07-01

    Full Text Available Abstract Background According to WHO estimates, tuberculosis case detection rate in Tanzania is less than 50% and this poses a major challenge to control tuberculosis in the country. Currently, one of the defining criteria for suspecting tuberculosis is cough for two weeks or more. We wanted to find out whether the prevalence of tuberculosis was different in patients who reported cough for two weeks or more, compared to patients with cough for less than two weeks. Methods We conducted a cross sectional study in six health facilities in Dar es Salaam, between September and October 2007. All patients aged five years and above with cough were screened for pulmonary tuberculosis (PTB by smear microscopy. Patients were divided into two groups, those who coughed for less than two weeks ( Results A total of 65,530 patients attended outpatients department (OPD. Out of these, 2274 (3.5% patients reported cough. Among patients who reported cough, 2214 (97.4% remembered their cough duration. One thousand nine hundred and seventy three patients (89.1% coughed for ? 2 wks as compared to 241 (10.9% patients who coughed for Conclusion Detection of smear positive PTB among patients who coughed for less than two weeks was as high as for those who coughed for two weeks or more.

  13. Role of traditional healers in psychosocial support in caring for the orphans: A case of Dar-es Salaam City, Tanzania

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    Massila Mariam

    2005-07-01

    Full Text Available Abstract Orphans are an increasing problem in developing countries particularly in Africa; due to the HIV/AIDS pandemic; and needs collective effort in intervention processes by including all stakeholders right from the grass roots level. This paper attempts to present the role of traditional healers in psychosocial support for orphan children in Dar-es-Salaam City with special focus on those whose parents have died because of HIV/AIDS. Six traditional healers who were involved in taking care of orphans were visited at their "vilinge" (traditional clinics. In total they had 72 orphans, 31 being boys and 41 being girls with age range from 3 years to 19. It was learned that traditional healers, besides providing remedies for illnesses/diseases of orphans, they also provided other basic needs. Further, they even provided psychosocial support allowing children to cope with orphan hood life with ease. Traditional healers are living within communities at the grass roots level; and appear unnoticed hidden forces, which are involved in taking care of orphans. This role of traditional healers in taking care of orphans needs to be recognised and even scaling it up by empowering them both in financial terms and training in basic skills of psychosocial techniques in how to handle orphans, in order to reduce discrimination and stigmatisation in the communities where they live.

  14. Slow progression of HIV-1 infection in a cohort of antiretroviral naïve hotel workers in Dar es Salaam, Tanzania as defined by their CD4 cell slopes.

    Science.gov (United States)

    Bakari, Muhammad; Urassa, Willy; Mhalu, Fred; Biberfeld, Gunnel; Pallangyo, Kisali; Sandström, Eric

    2008-01-01

    Data on slow progression following HIV-1 infection in Africa are sparse. From a study on the natural history of HIV-1 infection in Dar es Salaam, Tanzania, an analysis of immunological and clinical data from 237 HIV-1 seropositive individuals was performed. Annual CD4 cell determinations were carried out by flow cytometry. None was on antiretroviral treatment. CD4+ cell slopes were obtained by fitting a linear regression model. A study population of 50 individuals with >3 CD4 cell determinations and followed for >5 y had a mean follow-up of 72.7 months, and mean 5.7 CD4+ cell determinations. With a criterion of maintaining a CD4 cell count >or=500 cells/ml, 8 of the 50 (16.0%) were long-term non-progressors (LTNP). With a definition of maintaining a CD4+ cell slope selection bias introduced during slope determination is presented. With no selection, 24 (23.3%) would have documented slow CD4 progression among those enrolled for 5 or more y regardless of CD4 determinations. PMID:17943637

  15. Polycyclic aromatic hydrocarbon (PAH) contamination of surface sediments and oysters from the inter-tidal areas of Dar es Salaam, Tanzania

    International Nuclear Information System (INIS)

    Surface sediment and oyster samples from the inter-tidal areas of Dar es Salaam were analyzed for 23 polycyclic aromatic hydrocarbons (PAHs) including the 16 compounds prioritized by US-EPA using GC/MS. The total concentration of PAHs in the sediment ranged from 78 to 25,000 ng/g dry weight, while oyster concentrations ranged from 170 to 650 ng/g dry weight. Hazards due to sediment contamination were assessed using Equilibrium Partitioning Sediment Benchmarks and Threshold Effect Levels. Diagnostic indices and principle component analysis were used to identify possible sources. Interestingly, no correlation between sediment and oyster concentrations at the same sites was found. This is supported by completely different contamination patterns, suggesting different sources for both matrices. Hazard assessment revealed possible effects at six out of eight sites on the benthic communities and oyster populations. The contribution of PAH intake via oyster consumption to carcinogenic risks in humans seems to be low. - PAH contamination may pose hazards to benthos but limited risks to humans

  16. Red blood cell indices and prevalence of hemoglobinopathies and glucose 6 phosphate dehydrogenase deficiencies in male Tanzanian residents of Dar es Salaam

    Science.gov (United States)

    Mwakasungula, Solomon; Schindler, Tobias; Jongo, Said; Moreno, Elena; Kamaka, Kasimu; Mohammed, Mgeni; Joseph, Selina; Rashid, Ramla; Athuman, Thabit; Tumbo, Anneth Mwasi; Hamad, Ali; Lweno, Omar; Tanner, Marcel; Shekalaghe, Seif; Daubenberger, Claudia A

    2014-01-01

    Hemoglobinopathies, disorders of hemoglobin structure and production, are one of the most common monogenic disorders in humans. Glucose 6 phosphate dehydrogenase deficiency (G6PD) is an inherited enzymopathy resulting in increased oxygen stress susceptibility of red blood cells. The distributions of these genetic traits in populations living in tropical and subtropical regions where malaria has been or is still present are thought to result from survival advantage against severe life threatening malaria disease. 384 male Tanzanian volunteers residing in Dar es Salaam were typed for G6PD, sickle cell disease and ?-thalassemia. The most prominent red blood cell polymorphism was heterozygous ?+-thalassemia (37.8%), followed by the G6PD(A) deficiency (16.4%), heterozygous sickle cell trait (15.9%), G6PD(A-) deficiency (13.5%) and homozygous ?+-thalassemia (5.2%). 35%, 45%, 17% and 3% of these volunteers were carriers of wild type gene loci, one, two or three of these hemoglobinopathies, respectively. We find that using a cut off value of 28.6 pg. for mean corpuscular hemoglobin (MCH), heterozygous ?+-thalassemia can be predicted with a sensitivity of 84% and specificity of 72% in this male population. All subjects carrying homozygous ?+-thalassemia were identified based on their MCH value < 28.6 pg.

  17. Putting the genie back in the bottle? Availability and presentation of oral artemisinin compounds at retail pharmacies in urban Dar-es-Salaam

    Directory of Open Access Journals (Sweden)

    Black Carolyn

    2006-03-01

    Full Text Available Abstract Background Recently global health advocates have called for the introduction of artemisinin-containing antimalarial combination therapies to help curb the impact of drug-resistant malaria in Africa. Retail trade in artemisinin monotherapies could undermine efforts to restrict this class of medicines to more theoretically sound combination treatments. Methods This paper describes a systematic search for artemisinin-containing products at a random sample of licensed pharmacies in Dar-es-Salaam, Tanzania in July 2005. Results Nineteen different artemisinin-containing oral pharmaceutical products, including one co-formulated product, one co-packaged product, and 17 monotherapies were identified. All but one of the products were legally registered and samples of each product were obtained without a prescription. Packaging and labeling of the products seldom included local language or illustrated instructions for low-literate clients. Packaging and inserts compared reasonably well with standards recommended by the national regulatory authority with some important exceptions. Dosing instructions were inconsistent, and most recommended inadequate doses based on international standards. None of the monotherapy products mentioned potential benefits of combining the treatment with another antimalarial drug. Conclusion The findings confirm the widespread availability of artemisinin monotherapies that led the World Health Organization to call for the voluntary withdrawal of these drugs in malaria-endemic countries. As the global public health community gathers resources to deploy artemisinin-containing combination therapies in Africa, planners should be mindful that these drugs will coexist with artemisinin monotherapies in an already well-established market place. In particular, regulatory authorities should be incorporated urgently into the process of planning for rational deployment of artemisinin-containing antimalarial combination therapies.

  18. A tool box for operational mosquito larval control: preliminary results and early lessons from the Urban Malaria Control Programme in Dar es Salaam, Tanzania

    Directory of Open Access Journals (Sweden)

    Govella Nico J

    2008-01-01

    Full Text Available Abstract Background As the population of Africa rapidly urbanizes, large populations could be protected from malaria by controlling aquatic stages of mosquitoes if cost-effective and scalable implementation systems can be designed. Methods A recently initiated Urban Malaria Control Programme in Dar es Salaam delegates responsibility for routine mosquito control and surveillance to modestly-paid community members, known as Community-Owned Resource Persons (CORPs. New vector surveillance, larviciding and management systems were designed and evaluated in 15 city wards to allow timely collection, interpretation and reaction to entomologic monitoring data using practical procedures that rely on minimal technology. After one year of baseline data collection, operational larviciding with Bacillus thuringiensis var. israelensis commenced in March 2006 in three selected wards. Results The procedures and staff management systems described greatly improved standards of larval surveillance relative to that reported at the outset of this programme. In the first year of the programme, over 65,000 potential Anopheles habitats were surveyed by 90 CORPs on a weekly basis. Reaction times to vector surveillance at observations were one day, week and month at ward, municipal and city levels, respectively. One year of community-based larviciding reduced transmission by the primary malaria vector, Anopheles gambiae s.l., by 31% (95% C.I. = 21.6–37.6%; p = 0.04. Conclusion This novel management, monitoring and evaluation system for implementing routine larviciding of malaria vectors in African cities has shown considerable potential for sustained, rapidly responsive, data-driven and affordable application. Nevertheless, the true programmatic value of larviciding in urban Africa can only be established through longer-term programmes which are stably financed and allow the operational teams and management infrastructures to mature by learning from experience.

  19. Evaluation of HIV antibody and antigen/antibody combination ELISAs for use in an alternative confirmatory HIV testing strategy in Dar es Salaam, Tanzania.

    Science.gov (United States)

    Aboud, Said; Urassa, Willy; Lyamuya, Eligius; Mhalu, Fred; Biberfeld, Gunnel

    2006-08-01

    The aim of this study was to evaluate the performance of two antibody enzyme-linked immunosorbent assays (ELISAs) [Vironostika Uni-Form II plus O and Enzygnost anti-HIV-1/2 Plus], and two antigen/antibody combination ELISAs [Murex and Vironostika HIV Uni-Form II] for use in an alternative confirmatory HIV diagnostic testing strategy in Dar es Salaam, Tanzania. Altogether, 1380 serum samples were included. All ELISA reactive samples were tested using the Inno-Lia antibody assay and discrepant samples were tested on the Innotest p24 antigen assay. Three hundred and one (21.8%) samples were confirmed HIV-1 antibody positive by Inno-Lia including 27/508 (5.3%) from blood donors, 65/511 (12.7%) from pregnant women and 209/361 (57.9%) from hospital patients. The sensitivity at initial testing was 100% (95% CI; 98.8-100%) for all assays except Vironostika Uni-Form II plus O (99.7%; 95% CI; 98.2-99.9%) which showed one false negative sample at initial testing but 100% sensitivity after repeat testing. The final specificity at repeat testing was 100% (95% CI; 99.7-100%) for Enzygnost anti-HIV-1/2 Plus, 99.4% (95% CI; 98.8-99.8%) for each of the antigen/antibody combination ELISAs and 97.9% (95% CI; 96.8-98.6%) for Vironostika plus O ELISA. An alternative confirmatory HIV testing strategy based on initial testing on any of the two antigen/antibody assays followed by testing of reactive samples on the Enzygnost anti-HIV-1/2 Plus assay gave 100% specificity (95% CI; 99.7-100%). PMID:16647764

  20. Informal support to first-parents after childbirth: a qualitative study in low-income suburbs of Dar es Salaam, Tanzania

    Directory of Open Access Journals (Sweden)

    Mbekenga Columba K

    2011-11-01

    Full Text Available Abstract Background In Tanzania, and many sub-Saharan African countries, postpartum health programs have received less attention compared to other maternity care programs and therefore new parents rely on informal support. Knowledge on how informal support is understood by its stakeholders to be able to improve the health in families after childbirth is required. This study aimed to explore discourses on health related informal support to first-time parents after childbirth in low-income suburbs of Dar es Salaam, Tanzania. Methods Thirteen focus group discussions with first-time parents and female and male informal supporters were analysed by discourse analysis. Results The dominant discourse was that after childbirth a first time mother needed and should be provided with support for care of the infant, herself and the household work by the maternal or paternal mother or other close and extended family members. In their absence, neighbours and friends were described as reconstructing informal support. Informal support was provided conditionally, where poor socio-economic status and non-adherence to social norms risked poor support. Support to new fathers was constructed as less prominent, provided mainly by older men and focused on economy and sexual matters. The discourse conveyed stereotypic gender roles with women described as family caretakers and men as final decision-makers and financial providers. The informal supporters regulated the first-time parents' contacts with other sources of support. Conclusions Strong and authoritative informal support networks appear to persist. However, poverty and non-adherence to social norms was understood as resulting in less support. Family health in this context would be improved by capitalising on existing informal support networks while discouraging norms promoting harmful practices and attending to the poorest. Upholding stereotypic notions of femininity and masculinity implies great burden of care for the women and delimited male involvement. Men's involvement in reproductive and child health programmes has the potential for improving family health after childbirth. The discourses conveyed contradicting messages that may be a source of worry and confusion for the new parents. Recognition, respect and raising awareness for different social actors' competencies and limitations can potentially create a health-promoting environment among families after childbirth.

  1. Seroprevalence of human immunodeficiency virus, hepatitis B and C viruses and syphilis infections among blood donors at the Muhimbili National Hospital in Dar Es Salaam, Tanzania

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    Lyamuya Eligius F

    2006-01-01

    Full Text Available Abstract Background According to the latest Tanzanian National AIDS Control Programme (NACP report a total of 147,271 individuals donated blood during the year 2002. However, blood safety remains an issue of major concern in transfusion medicine in Tanzania where national blood transfusion services and policies, appropriate infrastructure, trained personnel and financial resources are inadequate. Most of the donated blood is screened for HIV alone. Methods We determined among blood donors at Muhimbili National Hospital (MNH, the seroprevalence of human immunodeficiency virus (HIV, hepatitis C virus (HCV, hepatitis B surface antigen (HBsAg and syphilis by donor type, sex and age and to determine association, if any, in the occurrence of the pathogens. The sample included 1599 consecutive donors, 1424(89.1% males and 175 (10.9% females, who donated blood between April 2004 and May, 2005. Most of them 1125 (70.4% were replacement donors and a few 474 (29.6% voluntary donors. Their age (in years ranged from 16 to 69, and most (72.2% were between 20–39 years. Results Two hundred and fifty four (15.9% of the donated blood had serological evidence of infection with at least one pathogen and 28 (1.8% had multiple infections. The current seroprevalence of HIV, HBsAg, HCV and syphilis among blood donors at MNH in Dar es Salaam was found to be 3.8%, 8.8%, 1.5% and 4.7%, respectively. Respective seroprevalences among HIV seronegative blood donors were 8.7% for HBV, 1.6% for HCV and 4.6% for syphilis. The differences in the prevalence of HIV and syphilis infections between replacement and voluntary donors were statistically significant (P 2 = 58.5 df = 5, P Conclusion The high (15.9% seroprevalence of blood-borne infections in blood donated at MNH calls for routine screening of blood donors for HBV, HCV, HIV and syphilis and for strict selection criteria of donors, with emphasis on getting young voluntary donors and for establishment of strict guidelines for blood transfusions.

  2. Low utilization of health care services following screening for hypertension in Dar es Salaam (Tanzania: a prospective population-based study

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    Lengeler Christian

    2008-12-01

    Full Text Available Abstract Background Drug therapy in high-risk individuals has been advocated as an important strategy to reduce cardiovascular disease in low income countries. We determined, in a low-income urban population, the proportion of persons who utilized health services after having been diagnosed as hypertensive and advised to seek health care for further hypertension management. Methods A population-based survey of 9254 persons aged 25–64 years was conducted in Dar es Salaam. Among the 540 persons with high blood pressure (defined here as BP ? 160/95 mmHg at the initial contact, 253 (47% had high BP on a 4th visit 45 days later. Among them, 208 were untreated and advised to attend health care in a health center of their choice for further management of their hypertension. One year later, 161 were seen again and asked about their use of health services during the interval. Results Among the 161 hypertensive persons advised to seek health care, 34% reported to have attended a formal health care provider during the 12-month interval (63% public facility; 30% private; 7% both. Antihypertensive treatment was taken by 34% at some point of time (suggesting poor uptake of health services and 3% at the end of the 12-month follow-up (suggesting poor long-term compliance. Health services utilization tended to be associated with older age, previous history of high BP, being overweight and non-smoking, but not with education or wealth. Lack of symptoms and cost of treatment were the reasons reported most often for not attending health care. Conclusion Low utilization of health services after hypertension screening suggests a small impact of a patient-centered screen-and-treat strategy in this low-income population. These findings emphasize the need to identify and address barriers to health care utilization for non-communicable diseases in this setting and, indirectly, the importance of public health measures for primary prevention of these diseases.

  3. ‘For someone who’s rich, it’s not a problem’ : Insights from Tanzania on diabetes health-seeking and medical pluralism among Dar es Salaam’s urban poor

    DEFF Research Database (Denmark)

    Kolling, Marie; Winkley, Kirsty

    2010-01-01

    The prevalence of chronic non-communicable disease, such as type 2 diabetes mellitus (T2DM), is rising worldwide. In Africa, T2DM is primarily affecting those living in urban areas and increasingly affecting the poor. Diabetes management among urban poor is an area of research that has received little attention. Based on ethnographic fieldwork in Dar es Salam, the causes and conditions for diabetes management in Tanzania have been examined. In this paper, we focus on the structural context of diabetes services in Tanzania; the current status of biomedical and ethnomedical health care; and health-seeking among people with T2DM. We demonstrate that although Tanzania is actively developing its diabetes services, many people with diabetes and low socioeconomic status are unable to engage continuously in treatment. There are many challenges to be addressed to support people accessing diabetes health care services and improve diabetes management.

  4. Putting the genie back in the bottle? Availability and presentation of oral artemisinin compounds at retail pharmacies in urban Dar-es-Salaam

    OpenAIRE

    Black Carolyn; Patrick, Kachur S.; Abdulla Salim; Goodman Catherine

    2006-01-01

    Abstract Background Recently global health advocates have called for the introduction of artemisinin-containing antimalarial combination therapies to help curb the impact of drug-resistant malaria in Africa. Retail trade in artemisinin monotherapies could undermine efforts to restrict this class of medicines to more theoretically sound combination treatments. Methods This paper describes a systematic search for artemisinin-containing products at a random sample of licensed pharmacies in Dar-e...

  5. Management of neonatal sepsis at Muhimbili National Hospital in Dar es Salaam: diagnostic accuracy of C ¿ reactive protein and newborn scale of sepsis and antimicrobial resistance pattern of etiological bacteria.

    Science.gov (United States)

    Mkony, Martha; Mizinduko, Mucho; Massawe, Augustine; Matee, Mecky

    2014-12-01

    BackgroundWe determined the accuracy of Rubarth¿s newborn scale of sepsis and C- reactive protein in diagnosing neonatal sepsis and assessed antimicrobial susceptibility pattern of etiological bacteria.MethodsThis cross sectional study was conducted at Muhimbili National Hospital in Dar es Salaam, Tanzania between July 2012 and March 2013. Neonates suspected to have sepsis underwent physical examination using Rubarth¿s newborn scale of sepsis (RNSOS). Blood was taken for culture and antimicrobial sensitivity testing, full blood picture and C ¿ reactive protein (CRP) performed 12 hours apart. The efficacy of RNSOS and serial CRP was assessed by calculating sensitivity, specificity, negative and positive predictive values, receiver operating characteristics(ROC) analysis as well as likelihood ratios (LHR) with blood culture result used as a gold standard.ResultsOut of 208 blood samples, 19.2% had a positive blood culture. Single CRP had sensitivity and specificity of 87.5% and 70.9% respectively, while RNSOS had sensitivity of 65% and specificity of 79.7%. Serial CRP had sensitivity of 69.0% and specificity of 92.9%. Combination of CRP and RNSOS increased sensitivity to 95.6%and specificity of 56.4%. Combination of two CRP and RNSOS decreased sensitivity to 89.1% but increased specificity to 74%.ROC for CRP was 0.86; and for RNSOS was 0.81.For CRP the LHR for positive test was 3 while for negative test was 0.18, while for RNSOS the corresponding values were 3.24 and for negative test was 0.43.Isolated bacteria were Klebsiella spp 14 (35%), Escherichia coli 12 (22.5%), Coagulase negative staphlococci 9(30%), Staphylococcus aureus4 (10%), and Pseudomonas spp 1(2.5%). The overall resistance to the WHO recommended first line antibiotics was 100%, 92% and 42% for cloxacillin, ampicillin and gentamicin, respectively. For the second line drugs resistance was 45%, 40%, and 7% for ceftriaxone, vancomycin and amikacin respectively.ConclusionsSingle CRP in combination with RNSOS can be used for rapid identification of neonates with sepsis due to high sensitivity (95.6%) but cannot exclude those without sepsis due to low specificity (56.4%). Serial CRP done 12hrs apart can be used to exclude non-cases. This study demonstrated very high levels of resistance to the first-line antibiotics. PMID:25475836

  6. Child trafficking in Tanzania:Experiences of Trafficked Girls in Dar es Salaam

    OpenAIRE

    Kavishe, Angela

    2011-01-01

    This study focuses on the experiences of trafficked children in Tanzania. Trafficking of children deprives them of human rights and freedoms; it may also pose a public health risk. Migration of children who are fostered by extended family is a long-standing customary practice in Tanzania, but while the circumstances of fostering have changed, given increasing rural poverty and the impact of the HIV/AIDS, this has not been recognized in Tanzanian society. The government enacted the Anti-Traffi...

  7. Drug use in pregnancy: Knowledge of drug dispensers and pregnant women in Dar es Salaam, Tanzania

    OpenAIRE

    Kamuhabwa, Appolinary; Jalal, Rashida

    2011-01-01

    More than 90% of pregnant women take prescription or non-prescription drugs at some time during pregnancy. In general, unless absolutely necessary, drugs should not be used during pregnancy because many of them are harmful to the fetus. Appropriate dispensing is one of the steps for rational drug use; so, it is necessary that drug dispensers should have relevant and updated knowledge and skills regarding drug use in pregnancy. To assess the knowledge of drug dispensers and pregnant women rega...

  8. Informal Urban Settlements and Cholera Risk in Dar es Salaam, Tanzania

    OpenAIRE

    Penrose, Katherine; Castro, Marcia C.; Werema, Japhet; Ryan, Edward Thomas

    2010-01-01

    Background: As a result of poor economic opportunities and an increasing shortage of affordable housing, much of the spatial growth in many of the world's fastest-growing cities is a result of the expansion of informal settlements where residents live without security of tenure and with limited access to basic infrastructure. Although inadequate water and sanitation facilities, crowding and other poor living conditions can have a significant impact on the spread of infectious diseases, analys...

  9. Introduction of a qualitative perinatal audit at Muhimbili National Hospital, Dar es Salaam, Tanzania

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    Thomas Angela N

    2009-09-01

    Full Text Available Abstract Background Perinatal death is a devastating experience for the mother and of concern in clinical practice. Regular perinatal audit may identify suboptimal care related to perinatal deaths and thus appropriate measures for its reduction. The aim of this study was to perform a qualitative perinatal audit of intrapartum and early neonatal deaths and propose means of reducing the perinatal mortality rate (PMR. Methods From 1st August, 2007 to 31st December, 2007 we conducted an audit of perinatal deaths (n = 133 with birth weight 1500 g or more at Muhimbili National Hospital (MNH. The audit was done by three obstetricians, two external and one internal auditors. Each auditor independently evaluated the cases narratives. Suboptimal factors were identified in the antepartum, intrapartum and early neonatal period and classified into three levels of delay (community, infrastructure and health care. The contribution of each suboptimal factor to adverse perinatal outcome was identified and the case graded according to possible avoidability. Degree of agreement between auditors was assessed by the kappa coefficient. Results The PMR was 92 per 1000 total births. Suboptimal factors were identified in 80% of audited cases and half of suboptimal factors were found to be the likely cause of adverse perinatal outcome and were preventable. Poor foetal heart monitoring during labour was indirectly associated with over 40% of perinatal death. There was a poor to fair agreement between external and internal auditors. Conclusion There are significant areas of care that need improvement. Poor monitoring during labour was a major cause of avoidable perinatal mortality. This type of audit was a good starting point for quality assurance at MNH. Regular perinatal audits to identify avoidable causes of perinatal deaths with feed back to the staff may be a useful strategy to reduce perinatal mortality.

  10. Formal and Informal Practices for Affordable Urban housing : Case study: Dar es Salaam, Tanzania

    OpenAIRE

    Mushumbusi, Medard Zephyrin

    2011-01-01

    This thesis attempts to ascertain the magnitude of the urban housingproblem in Tanzania and endeavours to evaluate the strategies that thegovernment has been employing to address this problem. Informal andformal practices in urban housing are compared. The role of networksand power relations are explored and discussed in relation to how theymay facilitate the provision of urban housing. By looking at urbanhousing from a governance perspective, the thesis explores thepotentials for delivery of...

  11. Travel behaviour in Cape Town, Dar Es Salaam and Nairobi cities.

    OpenAIRE

    Masaoe, Estomihi N.; Del Mistro, Romano F.; Makajuma, George

    2011-01-01

    Public and non-motorised transport facilities in urban centres in Africa are less than what is justified by the demand. This may be due to the way the urban transportation problem has been formulated and travel surveys carried out with a focus on establishing demand for travel by car. The aim of this study was to document travel behaviour in the three cities without bias to any of the modes so that Issues hindering the sustainable modes may be identifies and investigated. Household interviews...

  12. Factors for change in maternal and perinatal audit systems in Dar es Salaam hospitals, Tanzania

    OpenAIRE

    Kisanga Felix; Pembe Andrea B; Urassa David P; Nyamtema Angelo S; van Roosmalen Jos

    2010-01-01

    Abstract Background Effective maternal and perinatal audits are associated with improved quality of care and reduction of severe adverse outcome. Although audits at the level of care were formally introduced in Tanzania around 25 years ago, little information is available about their existence, performance, and practical barriers to their implementation. This study assessed the structure, process and impacts of maternal and perinatal death audit systems in clinical practice and presents a det...

  13. Housing Themselves : Transformations, Modernisation and Spatial qualities in Informal Settlements in Dar es Salaam, Tanzania

    OpenAIRE

    Nguluma, Huba

    2003-01-01

    This thesis is an attempt to address issues of housingtransformation in informal settlements. Transformation ofhouses is seen to be associated with modernisation forceswhereby people adapt their houses to suit their needs anddesires. On one hand the desire to own a?modernhouse?may lead to deterioration of spatial qualities, onthe other hand fulfilment of the desire may contribute to themodernisation of urban settlements. The informal settlement ofHanna Nassif was chosen as a case study to i...

  14. Managing Informal Settlements : A Study Using Geo-Information in Dar es Salaam, Tanzania

    OpenAIRE

    S?liuz?as, Ric?ardas Vytautas

    2004-01-01

    Urbanization in Sub-Saharan Africa (SSA) is often associated with the urbanization of poverty, and with the extensive development of informal settlements. This thesis examines how Geographic Information Technology (GIT) could be used to improve the ability of local governments in SSA manage such settlements. Three themes are at the core of this research: the evolution of thinking in the field of urban planning and management and the role of GIT as a planning support tool are discussed togethe...

  15. New tools for public participation in urban planning - a case from Dar es Salaam

    Directory of Open Access Journals (Sweden)

    Juma R Kiduanga

    2012-04-01

    Full Text Available

    Public Participation GIS har i efterhånden en del år været foreslået som et relevant redskab for bedre byplanlægning også i de hastigt voksende storbyer i udviklingslandene. Der synes dog ikke at være så mange eksempler på, at PPGIS er velintegreret i planprocessen. Denne artikel handler om nye tekniske muligheder for fælles kortlægning, registrering og deling af geografiske informationer gennem web-baserede services som f.eks. ArcGIS-Online. Vil sådanne kunne tages i anvendelse af berørte borgere og medvirke til en bedre byplanprocess og en forbedret retslig stilling for storbyens marginaliserede grupper, sådan som det har været foreslået?

  16. Evaluation of simple rapid HIV assays and development of national rapid HIV test algorithms in Dar es Salaam, Tanzania

    OpenAIRE

    Mbwana Judica; Sufi Jaffer; Urassa Willy K; Aboud Said; Lyamuya Eligius F; Ndugulile Faustin; Massambu Charles

    2009-01-01

    Abstract Background Suitable algorithms based on a combination of two or more simple rapid HIV assays have been shown to have a diagnostic accuracy comparable to double enzyme-linked immunosorbent assay (ELISA) or double ELISA with Western Blot strategies. The aims of this study were to evaluate the performance of five simple rapid HIV assays using whole blood samples from HIV-infected patients, pregnant women, voluntary counseling and testing attendees and blood donors, and to formulate an a...

  17. Medium and long-term adherence to postabortion contraception among women having experienced unsafe abortion in Dar es Salaam, Tanzania

    DEFF Research Database (Denmark)

    Rasch, Vibeke; Yambesi, Fortunata

    2008-01-01

    BACKGROUND: Postabortion contraceptive service is considered an effective means in addressing the problem of unsafe abortion; in spite this fact this component remains one of the weakest parts of postabortion care. In this context, the paper aims to describe the impact of a postabortion contraceptive service intervention among women admitted with complications from unsafe abortions and to explore the women's long-term contraceptive adherence. METHODS: 392 women having experienced unsafe abortion were identified by an empathetic approach and offered postabortion contraceptive service, which included counselling on HIV and condom use. Questionnaire interviews about contraceptive use were conducted at the time of inclusion and 12 months after the abortion. Additionally, in-depth interviews were performed 6-12 months after the abortion. RESULTS: Eighty-nine percent of the women accepted postabortion contraception. Follow-up information was obtained 12 months after the abortion among 59 percent of the women. Amongthese, 79 percent of the married women and 84 percent of the single women stated they were using contraception at 12 months. Condom use among the single women increased significantly during the 12 months follow up. CONCLUSION: Postabortion contraceptive services appear to be well accepted by women who are admitted with complications after an unsafe abortion and should thus be recognized as an important means in addressing the problem of unsafe abortion. In addition, counselling about HIV and condom use should be considered an essential aspect of postabortion care.

  18. Empowerment on microfinance entrepreneurs: social, economic and institutional power among small scale: entrepreneurs in Dar-Es-Salaam

    OpenAIRE

    Machado, Bruno

    2010-01-01

    Tanzania is one of the world’s poorest countries. Issues relating to poverty have largely been related with different forms of lack of power and, as such, this thesis presents itself with the goal of better understanding the relations between empowerment and poverty alleviation. It is assumed an empowerment model that, recognizes macroeconomic issues that underlie this problematic, but focuses on the concept of individual empowerment, and distinguishes three basic forms of power: social, in...

  19. The extension of Ubungo power plant in Dar es Salaam, Tanzania, to a combined cycle - A prestudy

    Energy Technology Data Exchange (ETDEWEB)

    Grinneland, L.; Oehrstroem, K.

    1996-05-01

    The report deals with the consequences concerning a future extension of Ubungo Power Plant. Today the power plant consists of four gas turbines, two of model General Electric LM6000 and two of model ABB Stal GT10 of which the latter were the ones focused on. In the report four different applications are presented; Simple two pressure system, Two pressure system with reheat, Two pressure system with heat exchange between feedwater and condensate, and single pressure system with an additional evaporating loop. The calculations are divided into three sections; thermodynamic calculations, calculations of the heat exchanger surface areas, and economic calculations. From the thermodynamic calculations the applications with the highest thermal efficiency was selected. The power output increased with about 55% and the thermal efficiency of the complete combined cycle is 48.2%. This is, of course, a theoretical value calculated without consideration to a number of losses that will decrease both the power output and the thermal efficiency. At part load (50% load assumed, i.e. one gas turbine is operating) the thermal efficiency is 46.7%. The economic calculations indicated that the extension is highly worthwhile in an economic point of view; both cases studied have a payback time of less than six years for full load operation, provided that the charging system which is to be imposed by the World Bank has come into force. 18 refs, 33 figs

  20. Medium and long-term adherence to postabortion contraception among women having experienced unsafe abortion in Dar es Salaam, Tanzania

    Directory of Open Access Journals (Sweden)

    Rasch Vibeke

    2008-07-01

    Full Text Available Abstract Background Postabortion contraceptive service is considered an effective means in addressing the problem of unsafe abortion; in spite this fact this component remains one of the weakest parts of postabortion care. In this context, the paper aims to describe the impact of a postabortion contraceptive service intervention among women admitted with complications from unsafe abortions and to explore the women's long-term contraceptive adherence. Methods 392 women having experienced unsafe abortion were identified by an empathetic approach and offered postabortion contraceptive service, which included counselling on HIV and condom use. Questionnaire interviews about contraceptive use were conducted at the time of inclusion and 12 months after the abortion. Additionally, in-depth interviews were performed 6–12 months after the abortion. Results Eighty-nine percent of the women accepted postabortion contraception. Follow-up information was obtained 12 months after the abortion among 59 percent of the women. Among these, 79 percent of the married women and 84 percent of the single women stated they were using contraception at 12 months. Condom use among the single women increased significantly during the 12 months follow up. Conclusion Postabortion contraceptive services appear to be well accepted by women who are admitted with complications after an unsafe abortion and should thus be recognized as an important means in addressing the problem of unsafe abortion. In addition, counselling about HIV and condom use should be considered an essential aspect of postabortion care.

  1. Community response to artemisinin-based combination therapy for childhood malaria: a case study from Dar es Salaam, Tanzania

    OpenAIRE

    Nyato Daniel J; Kamat Vinay R

    2010-01-01

    Abstract Background New malaria treatment guidelines in Tanzania have led to the large-scale deployment of artemether-lumefantrine (Coartem®), popularly known as ALu or dawa mseto. Very little is known about how people in malaria endemic areas interpret policy makers' decision to replace existing anti-malarials, such as sulphadoxine-pyrimethamine (SP) with "new" treatment regimens, such as ALu or other formulations of ACT. This study was conducted to examine community level understandings an...

  2. Primary antimicrobial resistance among Mycobacterium tuberculosis isolates from HIV seropositive and HIV seronegative patients in Dar es Salaam Tanzania

    OpenAIRE

    Bosch Ronald; Moshiro Candida; Msamanga Gernard; Villamor Eduardo; Mugusi Ferdinand; Urassa Willy; Saathoff Elmar; Fawzi Wafaie

    2008-01-01

    Abstract Background The United Republic of Tanzania is one of the 22 high M. tuberculosis burden countries. Data collected between 2002 and 2007 indicate that the global prevalence of drug-resistant M. tuberculosis including MDR vary greatly. The varied drug-resistance patterns make continuous surveillance of drug resistance an essential component of tuberculosis control program. Findings M. tuberculosis isolates were obtained from consenting adult tuberculosis patients involved in a placebo-...

  3. Critical Analysis of the Challenges of Solid Waste Management Initiatives in Keko Machungwa Informal Settlement, Dar es Salaam

    OpenAIRE

    Samson Elisha Kasala

    2014-01-01

    Solid waste is inevitable because by nature every human activity generates a certain amount of solid waste. The rate of solid waste generated tends to increase with the increase in population. Despite existence of various efforts on solid waste collection, still the quantity of solid waste collected is small compared to the solid waste generated. The situation is even worse in unplanned settlements of developing countries, where, ineffective solid waste collection is contributed to by haphaza...

  4. Community response to artemisinin-based combination therapy for childhood malaria: a case study from Dar es Salaam, Tanzania

    Directory of Open Access Journals (Sweden)

    Nyato Daniel J

    2010-02-01

    Full Text Available Abstract Background New malaria treatment guidelines in Tanzania have led to the large-scale deployment of artemether-lumefantrine (Coartem®, popularly known as ALu or dawa mseto. Very little is known about how people in malaria endemic areas interpret policy makers' decision to replace existing anti-malarials, such as sulphadoxine-pyrimethamine (SP with "new" treatment regimens, such as ALu or other formulations of ACT. This study was conducted to examine community level understandings and interpretations of ALu's efficacy and side-effects. The paper specifically examines the perceived efficacy of ALu as articulated by the mothers of young children diagnosed with malaria and prescribed ALu. Methods Participant observation, six focus group discussions in two large villages, followed by interviews with a random sample of 110 mothers of children less than five years of age, who were diagnosed with malaria and prescribed ALu. Additionally, observations were conducted in two village dispensaries involving interactions between mothers/caretakers and health care providers. Results While more than two-thirds of the mothers had an overall negative disposition toward SP, 97.5% of them spoke favourably about ALu, emphasizing it's ability to help their children to rapidly recover from malaria, without undesirable side-effects. 62.5% of the mothers reported that they were spending less money dealing with malaria than previously when their child was treated with SP. 88% of the mothers had waited for 48 hours or more after the onset of fever before taking their child to the dispensary. Mothers' knowledge and reporting of ALu's dosage was, in many cases, inconsistent with the recommended dosage schedule for children. Conclusion Deployment of ALu has significantly changed community level perceptions of anti-malarial treatment. However, mothers continue to delay seeking care before accessing ALu, limiting the impact of highly subsidized rollout of the drug. Implementation of ACT-based treatment guidelines must be complemented with educational campaigns to insure that mothers seek prompt help for their children within 24 hours of the onset of fever. Improved communication between health care providers and mothers of sick children can facilitate better adherence to ALu's recommended dosage. Community level interpretations of anti-malarials are multifaceted; integrating knowledge of local beliefs and practices surrounding consumption of anti-malarials into programmatic goals can help to significantly improve malaria control interventions.

  5. Implementation of the National Environment Policy: A case of the Local Government Authorities in Dar Es Salaam City- Tanzania

    OpenAIRE

    Mruma, Rosemary Oswald

    2005-01-01

    The government of Tanzania, with the support of a wide range of donors is implementing Local Government Reform Programmes. The three municipal councils of Ilala, Temeke and Kinondoni are among the Local government institutions in the 1st phase of the programme. The programme is one of the decentralized measures to improve service delivery at the local level, which includes management of the environment. The programmes are aimed at replacing the former control and command system of central gov...

  6. Oral manifestations of HIV infection in children and adults receiving highly active anti-retroviral therapy [HAART] in Dar es Salaam, Tanzania

    Directory of Open Access Journals (Sweden)

    Mikx Frans HM

    2006-08-01

    Full Text Available Abstract Background The aim of the study was to compare the prevalence and types of HIV-related oral lesions between children and adult Tanzanian patients on HAART with those not on HAART and to relate the occurrence of the lesions with anti-HIV drug regimen, clinical stage of HIV disease and CD4+ cell count. Methods Participants were 532 HIV infected patients, 51 children and 481 adults, 165 males and 367 females. Children were aged 2–17 years and adults 18 and 67 years. Participants were recruited consecutively at the Muhimbili National Hospital (MNH HIV clinic from October 2004 to September 2005. Investigations included; interviews, physical examinations, HIV testing and enumeration of CD4+ T cells. Results A total of 237 HIV-associated oral lesions were observed in 210 (39.5% patients. Oral candidiasis was the commonest (23.5%, followed by mucosal hyperpigmentation (4.7%. There was a significant difference in the occurrence of oral candidiasis (?2 = 4.31; df = 1; p = 0.03 and parotid enlargement (?2 = 36.5; df = 1; p = 0.04 between children and adults. Adult patients who were on HAART had a significantly lower risk of; oral lesions (OR = 0.32; 95% CI = 0.22 – 0.47; p = 0.005, oral candidiasis (OR = 0.28; 95% CI = 0.18 – 0.44; p = 0.003 and oral hairy leukoplakia (OR = 0.18; 95% CI = 0.04 – 0.85; p = 0.03. There was no significant reduction in occurrence of oral lesions in children on HAART (OR = 0.35; 95% CI = 0.11–1.14; p = 0.15. There was also a significant association between the presence of oral lesions and CD4+ cell count 3 (?2 = 52.4; df = 2; p = 0.006 and with WHO clinical stage (?2 = 121; df = 3; p = 0.008. Oral lesions were also associated with tobacco smoking (?2 = 8.17; df = 2; p = 0.04. Conclusion Adult patients receiving HAART had a significantly lower prevalence of oral lesions, particularly oral candidiasis and oral hairy leukoplakia. There was no significant change in occurrence of oral lesions in children receiving HAART. The occurrence of oral lesions, in both HAART and non-HAART patients, correlated with WHO clinical staging and CD4+ less than 200 cells/mm3.

  7. Challenges of caring for children with mental disorders: Experiences and views of caregivers attending the outpatient clinic at Muhimbili National Hospital, Dar es Salaam - Tanzania

    Directory of Open Access Journals (Sweden)

    Ambikile Joel

    2012-07-01

    Full Text Available Abstract Background It is estimated that world-wide up to 20?% of children suffer from debilitating mental illness. Mental disorders that pose a significant concern include learning disorders, hyperkinetic disorders (ADHD, depression, psychosis, pervasive development disorders, attachment disorders, anxiety disorders, conduct disorder, substance abuse and eating disorders. Living with such children can be very stressful for caregivers in the family. Therefore, determination of challenges of living with these children is important in the process of finding ways to help or support caregivers to provide proper care for their children. The purpose of this study was to explore the psychological and emotional, social, and economic challenges that parents or guardians experience when caring for mentally ill children and what they do to address or deal with them. Methodology A qualitative study design using in-depth interviews and focus group discussions was applied. The study was conducted at the psychiatric unit of Muhimbili National Hospital in Tanzania. Two focus groups discussions (FGDs and 8 in-depth interviews were conducted with caregivers who attended the psychiatric clinic with their children. Data analysis was done using content analysis. Results The study revealed psychological and emotional, social, and economic challenges caregivers endure while living with mentally ill children. Psychological and emotional challenges included being stressed by caring tasks and having worries about the present and future life of their children. They had feelings of sadness, and inner pain or bitterness due to the disturbing behaviour of the children. They also experienced some communication problems with their children due to their inability to talk. Social challenges were inadequate social services for their children, stigma, burden of caring task, lack of public awareness of mental illness, lack of social support, and problems with social life. The economic challenges were poverty, child care interfering with various income generating activities in the family, and extra expenses associated with the child’s illness. Conclusion Caregivers of mentally ill children experience various psychological and emotional, social, and economic challenges. Professional assistance, public awareness of mental illnesses in children, social support by the government, private sector, and non-governmental organizations (NGOs are important in addressing these challenges.

  8. THE EFFECT OF ENVIRONMENTAL REGULATIONS ON FINANCIAL PERFORMANCE IN TANZANIA: A SURVEY OF MANUFACTURING COMPANIES QUOTED ON THE DAR ES SALAAM STOCK EXCHANGE

    OpenAIRE

    Daniel Linus Naila

    2013-01-01

    There has been environmental pollution across the globe. Environmental activists are condemning manufacturing companies of environmental pollution. This has led to the establishment of environmental regulations and standards by government authorities across the globe. In complying with environmental regulations companies have found themselves incurring additional cost when compared to those companies which do not comply. However, the effect of compliance to environmental regulations on the fi...

  9. The use of an African language as language of instruction at university level:the example of Kiswahili department at the University of Dar-es-Salaam in Tanzania

    OpenAIRE

    Peterson, Rhoda

    2006-01-01

    ABSTRACT The issue of language of instruction in Tanzania has had a front seat for more than thirty years now. It seems the debate is generating more heat than light (Rubagumya, 2003; Kadeghe, 2003). Most of the research reports and publications show that English can no longer serve as the language of instruction at post primary level. Some researchers, basing on their findings, suggest that Kiswahili which is a well known language to almost every Tanzanian should replace English in order to...

  10. Considering the enabling goal of microfinance services in alleviating poverty in Tanzania, what are the poor people doing to make it work for them? The case of Ilala municipality, Dar es Salaam Region

    OpenAIRE

    Kawamala, Patience Nelson

    2012-01-01

    Tanzania is one of the poorest countries which have implemented microfinance services as one of the most effective methods of alleviating poverty. As a result several microfinance institutions have been established and people are involving themselves in these schemes to make use of this enabling goal. So, this study had a general objective of exploring people’s actions as they make use of the available microfinance services so as to alleviate poverty. The specific objectives were to explore...

  11. The social impact of microfinance: what changes in well-being are perceived by women group borrowers after obtaining a group loan? : A participatory rural appraisal in Dar es Salaam Region, Tanzania

    OpenAIRE

    Goey, Heleen

    2012-01-01

    Worldwide, poverty remains to be an obstacle to achieve sustainable development and improve the well-being of people. Microfinance has become a popular tool for poverty alleviation and it can now be found in poor countries across the world. Microfinance is based on the principle that poor people can initiate their own development out of poverty, given they have the starting capital to do so. The capital can be invested in income-generating activities and it is assumed that this will lead to a...

  12. Urbanisation and its discontents: urban refugees in Tanzania

    Directory of Open Access Journals (Sweden)

    Marc Sommers

    1999-04-01

    Full Text Available This article explores the different labels under which refugees in Dar es Salaam may be categorised. It identifies and profiles differentgroups of urban refugee in Dar es Salaam and considers some common assumptions about urban refugees.

  13. Urbanisation and its discontents: urban refugees in Tanzania

    OpenAIRE

    Marc Sommers

    1999-01-01

    This article explores the different labels under which refugees in Dar es Salaam may be categorised. It identifies and profiles differentgroups of urban refugee in Dar es Salaam and considers some common assumptions about urban refugees.

  14. Self-initiation of antiretroviral therapy in the developing world: the involvement of private pharmacies in an HIV program

    OpenAIRE

    Om, Minzi; Buma D; Ga, Kagashe

    2012-01-01

    Omary Mashiku Minzi1, Deus Buma2, Godeliver A Kagashe3 1Unit of Pharmacology and Therapeutics, School of Pharmacy, Muhimbili University of Health and Allied Sciences, Dar Es Salaam, Tanzania; 2Department of Pharmaceutics, School of Pharmacy, Muhimbili University of Health and Allied Sciences, Dar Es Salaam, Tanzania; 3Department of Pharmacy, Muhimbili National Hospital, Dar Es Salaam, TanzaniaBackground: Self-initiation to antiretroviral treatment (ART) exposes the patient to the risk of drug...

  15. Acute haemorrhagic conjunctivitis epidemics and outbreaks of Paederus spp. keratoconjunctivitis ('Nairobi red eyes') and dermatitis.

    Science.gov (United States)

    Mbonile, L

    2011-08-01

    An epidemic of acute conjunctivitis in Dar es Salaam in 2010 demonstrated the importance of a strong infectious diseases epidemiological surveillance network to minimise disease outbreaks. Misunderstanding of the causes and management of diseases explains the repetitive nature of acute haemorrhagic conjunctivitis (AHC) in Dar es Salaam. This paper discusses AHC and Paederus spp. keratoconjunctivitis and periorbital oedema ('Nairobi red eyes') that are confused as being associated with recurrent epidemics of conjunctivitis in Dar es Salaam. PMID:21920128

  16. Software packaging with DAR

    CERN Document Server

    Ratnikova, Natalia; Graham, Greg; Lefébure, V; Wildish, Tony

    2004-01-01

    One of the important tasks in distributed computing is to deliver software applications to the computing resources. Distribution after Release (DAR) tool, is being used to package software applications for the world-wide event production by the CMS Collaboration. This presentation will focus on the concept of packaging applications based on the runtime environment. We discuss solutions for more effective software distribution based on two years experience with DAR. Finally, we will give an overview of the application distribution process and the interfaces to the CMS production tools.

  17. Dar olhando a quem: estudo sobre o Projecto "Todo Homem é Meu Irmão" / Donner en regardant à qui on donne: Étude sur le projet "Tout homme est mon frère" / Do give looking at whom: Study on the project "Every man is my brother" / Dar mirando a quién: estudio acerca del Proyecto "Todo hombre es mi hermano"

    Scientific Electronic Library Online (English)

    Paulo, Reis Mourão.

    2013-07-01

    Full Text Available SciELO Colombia | Language: Portuguese Abstract in portuguese Este documento analisa o fenómeno da dádiva, através de um estudo de caso observado num diário português - o Jornal de Notícias. Este jornal acolhe, há várias décadas, o Projecto "Todo Homem é Meu Irmão". Este trabalho avalia quais os factores responsáveis pelos diferentes valores atribuídos aos dif [...] erentes beneficiários desse projecto. Conclui que são factores positivos a duração do pedido nas edições do jornal e o número de dependentes a cargo dos beneficiários. Conclui que são factores negativos a presença do beneficiário em categorias de rendimento superior assim como a autonomia de mobilidade. Os resultados mostram que o fenómeno da dádiva é complexo onde entram também, com influência, as características endógenas do beneficiário, para lá das dimensões que a literatura apontou previamente. Abstract in spanish Este documento analiza el fenómeno de la dádiva a través de un estudio de caso observado en un periódico portugués - el Jornal de Notícias. Ese periódico contiene, hace varias décadas, el Proyecto "Todo hombre es mi hermano". Este trabajo evalúa cuáles son los factores responsables por los diferente [...] s valores atribuidos a los distintos beneficiarios de ese proyecto. Se concluye que son factores positivos la duración del pedido en las ediciones del periódico y el número de dependientes a cargo de los beneficiarios. Además se concluye que son factores negativos la presencia del beneficiario en categorías de rendimiento superior así como la autonomía de movilidad. Los resultados muestran que el fenómeno de la dádiva es complejo donde entran también, con influencia, las características endógenas del beneficiario para más allá de las dimensiones que la literatura señaló previamente. Abstract in english This paper analyzes the gift phenomenon observing data from the Project "Every Man is my brother" (or Todo Homem é Meu Irmão). This Project has been supported by the Portuguese newspaper Jornal de Notícias for more than 30 years. This work evaluates which determinants influence the values given to e [...] ach case. This work concluded that the number of weeks for exposing each case in the pages of the newspaper and the number of children supported by each beneficiary positively influence the values that were given to this beneficiary. Higher individual incomes and self-mobility negatively influence the values that were given. These results show that the gift phenomenon is rather complex and it is also influenced by the endogenous characteristics of each receiver.

  18. Understanding of acute hemorrhagic conjunctivitis (AHC) epidemics and outbreaks of Paederus spp keratoconjuctivitis, periorbital oedema ("Nairobi red eyes") and dermatitis.

    Science.gov (United States)

    Mbonile, L

    2010-09-01

    A recent epidemic of acute conjunctivitis in Dar es Salaam showed again the importance of developing a strong infectious diseases epidemiological surveillance network which is effective in minimising disease outbreaks. The current misunderstanding of diseases causation and management explains the repetitive nature of acute hemorrhagic conjunctivitis (AHC) in Dar es Salaam. This article aims at increasing public awareness by elaborating two diseases (Acute Hemorrhagic Conjunctivitis and Paederus spp keratoconjuctivitis, periorbital oedema-"Nairobi red eyes") confused by many as being associated with recurrent epidemics of conjunctivitis Dar es Salaam. PMID:21516962

  19. Acute haemorrhagic conjunctivitis epidemics and outbreaks of Paederus spp. keratoconjunctivitis ('Nairobi red eyes') and dermatitis

    Scientific Electronic Library Online (English)

    L, Mbonile.

    2011-08-01

    Full Text Available SciELO South Africa | Language: English Abstract in english An epidemic of acute conjunctivitis in Dar es Salaam in 2010 demonstrated the importance of a strong infectious diseases epidemiological surveillance network to minimise disease outbreaks. Misunderstanding of the causes and management of diseases explains the repetitive nature of acute haemorrhagic [...] conjunctivitis (AHC) in Dar es Salaam. This paper discusses AHC and Paederus spp. keratoconjunctivitis and periorbital oedema ('Nairobi red eyes') that are confused as being associated with recurrent epidemics of conjunctivitis in Dar es Salaam.

  20. Oral health behavior patterns among Tanzanian university students: a repeat cross-sectional survey

    OpenAIRE

    Åstrøm Anne; Masalu Joyce

    2001-01-01

    Abstract Purpose This study examines oral health behavioral trends and the development of sociodemographic differences in oral health behaviors among Tanzanian students between 1999 and 2000. Methods The population targeted was students attending the Muhimbili University College of Health Sciences (MUCHS) at the University of Dar es Salaam (UDSM), Dar es Salaam, Tanzania. Cross-sectional surveys were conducted and a total of 635 and 981 students, respectively, completed questionnaires in 1999...

  1. Application of basic pharmacology and dispensing practice of antibiotics in accredited drug-dispensing outlets in Tanzania

    OpenAIRE

    Om, Minzi; Vs, Manyilizu

    2013-01-01

    OM Minzi,1 VS Manyilizu21Unit of Pharmacology and Therapeutics, School of Pharmacy, Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania, 2Logistics System Strengthening Unit, John Snow Inc, Dar es Salaam, TanzaniaBackground: Provision of pharmaceutical services in accredited drug-dispensing outlets (ADDOs) in Tanzania has not been reported. This study compared the antibiotics dispensing practice between ADDOs and part II shops, or duka la dawa baridi (DLDBs), in Tanzan...

  2. Fytoremediering av tungmetall förorenade jordar genom användning av lokala växter i Msimbazi flodens avrinningsområde, Tanzania.

    OpenAIRE

    O?sterling, Eskil

    2011-01-01

    This master thesis is a study of the feasibility of in situ soil remediation techniques in Dar es Salaam, Tanzania. It first looks at the existing on site remediation techniques and assesses how feasible they appear in the conditions of Dar es Salaam. Two methods were interpreted as more feasible than others, namely reactive zone remediation and phytoremediation. The feasibility of phytoremediation was assessed by sampling locally occurring plants and comparing their content of Cu, Pb and Zn ...

  3. Tri-Lateral Noor al Salaam High Concentration Solar Central Receiver Program

    Energy Technology Data Exchange (ETDEWEB)

    Blackmon, James B

    2008-03-31

    This report documents the efforts conducted primarily under the Noor al Salaam (“Light of Peace”) program under DOE GRANT NUMBER DE-FC36-02GO12030, together with relevant technical results from a closely related technology development effort, the U.S./Israel Science and Technology Foundation (USISTF) High Concentration Solar Central Receiver program. These efforts involved preliminary design, development, and test of selected prototype power production subsystems and documentation of an initial version of the system definition for a high concentration solar hybrid/gas electrical power plant to be built in Zaafarana, Egypt as a first step in planned commercialization. A major part of the planned work was halted in 2007 with an amendment in October 2007 requiring that we complete the technical effort by December 31, 2007 and provide a final report to DOE within the following 90 days. This document summarizes the work conducted. The USISTF program was a 50/50 cost-shared program supported by the Department of Commerce through the U.S./Israel Science and Technology Commission (USISTC). The USISTC was cooperatively developed by President Clinton and the late Prime Minister Rabin of Israel "to encourage technological collaboration" and "support peace in the Middle East through economic development". The program was conducted as a follow-on effort to Israel's Magnet/CONSOLAR Program, which was an advanced development effort to design, fabricate, and test a solar central receiver and secondary optics for a "beam down" central receiver concept. The status of these hardware development programs is reviewed, since they form the basis for the Noor al Salaam program. Descriptions are provided of the integrated system and the major subsystems, including the heliostat, the high temperature air receiver, the power conversion unit, tower and tower reflector, compound parabolic concentrator, and the master control system. One objective of the USISTF program was to conduct marketing research, identify opportunities for use of this technology, and to the extent possible, secure an agreement leading to a pre-commercialization demonstration or prototype plant. This was accomplished with the agreement to conduct the Noor al Salaam program as a tri-lateral project between Egypt, Israel, and the U.S. The tri-lateral project was led by the University of Alabama in Huntsville (UAH); this included the Egyptian New and Renewable Energy Authority and the Israeli USISTC participants. This project, known was Noor al Salaam, was funded by the U.S. Agency for International Development (USAID) through the Department of Energy (DOE). The Egyptian activity was under the auspices of the Egyptian Ministry of Energy and Electricity, New and Renewable Energy Authority (NREA) as part of Egypt's plans for renewable energy development. The objective of the Noor al Salaam project was to develop the conditions necessary to obtain funding and construct and operate an approximately 10 to 20 Megawatt hybrid solar/natural gas demonstration power plant in Zaafarana, Egypt that could serve both as a test bed for advanced solar technology evaluations, and as a forerunner to commercial plant designs. This plant, termed Noor Al Salaam, or “Light of Peace”, reached the initial phase of system definition before being curtailed, in part by changes in USAID objectives, coupled with various delays that were beyond the scope of the program to resolve. The background of the USISTF technology development and pre-commercialization effort is provided in this report, together with documentation of the technology developments conducted under the Noor al Salaam program. It should be noted that only a relatively small part of the Noor al Salaam funding was expended over the approximately five years for which UAH was prime contractor before the program was ordered closed (Reference 1) so that the remaining funds could be returned to USAID.

  4. APLICACIÓN DE DATOS LiDAR EN LA ESTIMACIÓN DEL VOLUMEN FORESTAL EN EL PARQUE METROPOLITANO BOSQUE SAN CARLOS / APPLICATION LiDAR DATA IN ESTIMATING FOREST VOLUME IN THE METROPOLITAN PARK SAN CARLOS

    Scientific Electronic Library Online (English)

    Cristian Danilo, Martínez Tobón; Jhon Eric, Aunta Duarte; Jorge Alberto, Valero Fandiño.

    2013-01-01

    Full Text Available RESUMEN La tecnología LiDAR es una de las fuentes de información geográfica que permite obtener puntos de coordenadas incluyendo la altura con mayor precisión. Una de las principales aplicaciones que tiene LiDAR es en el sector forestal, pero que en Colombia el poco desarrollo de este sector limita [...] explorar la conveniencia del uso de datos LiDAR para estimar recursos forestales. El presente trabajo explora el uso de datos LiDAR para la estimación del Volumen Forestal en el Parque Metropolitano Bosque San Carlos en Bogotá D.C. Se establece un marco de antecedentes con estudios similares, se analiza un grupo de herramientas informáticas para el manejo de los datos LiDAR y posteriormente, se establece un procedimiento metodológico para obtener un modelo de regresión que relacione los datos de altura normalizados, con la variable de campo de Volumen Forestal. Se realizan análisis de regresión apoyado en criterios de decisión estadísticos probando varios modelos para seleccionar las variables que mejor representen el fenómeno, se establece la prueba de bondad de ajuste tanto del modelo como de sus parámetros. Aunque el modelo que se obtiene no arrojo los resultados esperados en términos de la estimación del Volumen Forestal se analizan las causas de que eso ocurra. Finalmente, se valida el modelo aplicándolo para la totalidad de la zona de estudio y se representa geográficamente a través de un mapa temático. Abstract in english ABSTRACT LiDAR technology is a source of geographic information for obtaining coordinate points including height, with more accurately, one of the main applications is having LiDAR in forestry, but in Colombia the underdevelopment of this sector limits explore the convenience of using LiDAR data to [...] estimate forest resources. This paper explores the use of LiDAR data for estimating forest volume in Metropolitan Park Forest San Carlos in Bogota DC Establishing a framework for background with similar studies; analyze a group of tools to manage LiDAR data and subsequently establishing a methodological procedure for a regression model relating the standard height data, with variable field, forest volume. Regression analysis was performed on decision criteria supported statistical testing various models to select the variables that best represent the phenomenon, establishing the goodness of fit test of the model and its parameters. Although the model is obtained did not produce the expected results in terms of estimating forest volume examines the causes of that happening. Finally the model is validated by applying it to the entire study area and represented geographically through a thematic map.

  5. Aplicación del LiDAR aerotransportado a la determinación de la altura de grandes estructuras. Caso de estudio: Presas / Application of Airborne LiDAR to the Determination of the Height of Large Structures. Case Study: Dams

    Scientific Electronic Library Online (English)

    Rubén, Martínez Marín; Juan Gregorio, Rejas Ayuga; Miguel, Marchamalo Sacristán.

    2014-03-01

    Full Text Available La mejor forma de calcular la altura de una presa es realizar una nivelación geométrica de precisión. No obstante, este método es demandante y costoso. La precisión de los datos obtenidos ha mejorado sustancialmente, esta tecnología puede proveer precisiones de 2 a 3 centímetros, más que suficiente [...] para determinar la altura de presa y utilizar ésta como dato de partida para cualquier actividad posterior que así lo requiera. La densidad de adquisición de los datos LiDAR (Light Detection and Ranging) es importante para establecer la bondad de los resultados. Finalmente, como los sistemas LiDAR aerotransportados están basados en alturas elipsoidales, es necesario transformarlas a ortométricas. Este trabajo muestra los resultados obtenidos usando un LiDAR de baja densidad (0.5 pts/m²) y su validación con observaciones GPS (Global Positioning System) en postproceso. Los resultados demuestran que se puede obtener una precisión del orden de 10-25 cm, suficiente para la mayoría de las actividades relacionadas con la ingeniería civil. Abstract in english The best way to determine the height of dams is to level the top of the dam applying a geometric leveling. Nevertheless this task is very demanding and expensive. The accuracy potential of LiDAR (Light Detection and Ranging) data has significantly improved. These systems can provide accuracy of 2-3 [...] cm level, which could be enough to be applied in the determination of the height of dams. The point acquisition density is an important factor involved in the process of determining the height using LiDAR technique. Finally, since the LiDAR technique is based on ellipsoidal heights, the coordinates must be transformed to the official orthometric system. This paper shows the results obtained using low density airborne LiDAR data (0.5 pts/m²) and their validation with post-processed GPS (Global Positioning System) observations. Test results have shown LiDAR can be accurate enough (10-25 cm) to determine the height and to be applied in many civil engineering activities.

  6. Direct Georeferencing of Stationary LiDAR

    Directory of Open Access Journals (Sweden)

    Ahmed Mohamed

    2009-12-01

    Full Text Available Unlike mobile survey systems, stationary survey systems are given very little direct georeferencing attention. Direct Georeferencing is currently being used in several mobile applications, especially in terrestrial and airborne LiDAR systems. Georeferencing of stationary terrestrial LiDAR scanning data, however, is currently performed indirectly through using control points in the scanning site. The indirect georeferencing procedure is often troublesome; the availability of control stations within the scanning range is not always possible. Also, field procedure can be laborious and involve extra equipment and target setups. In addition, the conventional method allows for possible human error due to target information bookkeeping. Additionally, the accuracy of this procedure varies according to the quality of the control used. By adding a dual GPS antenna apparatus to the scanner setup, thereby supplanting the use of multiple ground control points scattered throughout the scanning site, we mitigate not only the problems associated with indirect georeferencing but also induce a more efficient set up procedure while maintaining sufficient precision. In this paper, we describe a new method for determining the 3D absolute orientation of LiDAR point cloud using GPS measurements from two antennae firmly mounted on the optical head of a stationary LiDAR system. In this paper, the general case is derived where the orientation angles are not small; this case completes the theory of stationary LiDAR direct georeferencing. Simulation and real world field experimentation of the prototype implementation suggest a precision of about 0.05 degrees (~1 milli-radian for the three orientation angles.

  7. ¿Es la psiquiatría una ciencia?.

    Directory of Open Access Journals (Sweden)

    Francesc Roca i Sebastià

    1999-01-01

    Full Text Available No es habitual la elección de una pregunta como título, y menos una pregunta que entra en conflicto con una verdad tenida por obvia y comúnmente aceptada. No obstante la he elegido para introducir un artículo en el que trataré de dar cuenta de una hipótesis con la que pretendo cuestionarme justamente lo obvio de esta verdad de aceptación común, especialmente en lo que a la práctica clínica de la psiquiatría se refiere, y sus consecuencias: considero que, en la época de la técnica en la que vivimos, la clínica médica, y por tanto también la práctica clínica de la psiquiatría, está comprometida en sí misma, presa de la contradicción en la que nace como modo de practicar la medicina, la exclusión en dicha práctica del enfermo en tanto que sujeto capaz de narrar su propia historia, capaz de darse a sí mismo un tiempo subjetivo distinto de la mera cronología, lo que hace que su existencia tenga un valor distinto al del fenómeno.

  8. Decay of 248Es

    International Nuclear Information System (INIS)

    The electron capture and alpha decays of 248Es was studied. Previous experiments have identified 248Es by means of the 6.87 MeV alpha particles from its 0.25% alpha decay branch, but because of a lack of target material or an inappropriate choice of reaction, detailed studies of the decay properties of 248Es were not possible. In the present experiments, a much larger and cleaner source of 248Es was made available. Many gamma rays have been found to accompany the electron capture decay of 248Es. The gamma ray and alpha decay data from the present experiments support the existence of two isomers of 248Es

  9. Application of LiDAR technology for hydroelectric operations

    Energy Technology Data Exchange (ETDEWEB)

    McArdle, Steven; Grover, Patrick; Hellas, Neil [4DM Inc., Toronto, (Canada); Bryan, Nick; Kirkham, Allan; Lim, Sony [Ontario Power Generation, Toronto, (Canada)

    2010-07-01

    Airborne LiDAR technology that uses On the Fly GPS techniques with portable IMU systems has shown strong growth in the last five years. In 2007, Ontario Power Generation (OPG) developed a pilot project to introduce the concept of airborne LiDAR technology for mapping and hydrotechnical studies as a viable option for acquiring accurate elevation data in forested areas of Northern Ontario. LiDAR data have been collected on over 12,000 sq km for 19 river systems since 2008. This paper reported the review of the acquisition and data processing methodology for the application of LiDAR technology to hydroelectric operations. It focused on providing insight into using the technology for hydropower planning and operations and illustrated the benefits of LiDAR over case studies for hydroelectric applications. The LiDAR data sets illustrated the significant advantages for detail terrain mapping for OPG. This technology is still evolving. Data collection and review is ongoing.

  10. Akkuraatheidseffek van LiDAR-datavermindering op digitale hoogtemodelle

    Directory of Open Access Journals (Sweden)

    Jaco Immelman

    2011-09-01

    Full Text Available The effects of data reduction on remotely sensed LiDAR-based DEMs
    LiDAR-derived DEMs can take weeks to process, thus minimising the effectiveness of timely solutions. In order to reach realistic processing times, data sets need to be reduced. However, data reduction needs to be conducted with the minimum loss of accuracy. This study investigates the effects of data reduction on LiDAR-derived DEMs.

  11. Extraction of Mangrove Biophysical Parameters Using Airborne LiDAR

    OpenAIRE

    Poonsak Miphokasap; Phisan Santitamnont; Kiyoshi Honda; Wasinee Wannasiri; Masahiko Nagai

    2013-01-01

    Tree parameter determinations using airborne Light Detection and Ranging (LiDAR) have been conducted in many forest types, including coniferous, boreal, and deciduous. However, there are only a few scientific articles discussing the application of LiDAR to mangrove biophysical parameter extraction at an individual tree level. The main objective of this study was to investigate the potential of using LiDAR data to estimate the biophysical parameters of mangrove trees at an individual tree scal...

  12. LiDAR Utility for Natural Resource Managers

    OpenAIRE

    Alistair Matthew Stuart Smith; Andrew Thomas Hudak; Jeffrey Scott Evans

    2009-01-01

    Applications of LiDAR remote sensing are exploding, while moving from the research to the operational realm. Increasingly, natural resource managers are recognizing the tremendous utility of LiDAR-derived information to make improved decisions. This review provides a cross-section of studies, many recent, that demonstrate the relevance of LiDAR across a suite of terrestrial natural resource disciplines including forestry, fire and fuels, ecology, wildlife, geology, geomorphology, and surface ...

  13. Trapped in decline: a sociological analysis of economic life in Mgeta, Uluguru mountains Tanzania.

    OpenAIRE

    Donge, J. K.

    1993-01-01

    The research for this thesis was carried out in Tanzania during the period 1985- 89 and focuses on the Mgeta division in the Uluguru mountains, Morogoro rural district. Research was also undertaken among migrants from the area living in Dar es Salaam where they traded in foodstuffs. I made a return visit to the area in November 1991 to look again at questions which arose during writing up. The research also reflects seven years' employment at the University of Dar es Salaam (1982-89). The Tan...

  14. LiDAR Elevation and DEM Errors in Forested Settings

    Directory of Open Access Journals (Sweden)

    Curtis Edson

    2014-11-01

    Full Text Available igital elevation models (DEMs form the basis of LiDAR derived tree height measurements and other topographic modeling needs within natural resource applications. We compared 2873 digital total station elevations to the closest discrete LiDAR elevation point and DEM raster cell across several forest and topographic settings. We also examined limiting comparisons to points within 0.5 m and within one meter. Using all nearest LiDAR points, average total station plot elevation differences ranged from -0.06 m (SD 0.40 to -0.59 m (SD 0.23 indicating that LiDAR elevations are higher than actual elevations. LiDAR DEM differences ranged from -0.09 (SD 0.41 to -0.56 m (SD 0.70. We also compared mapping-grade GPS receiver measurements to LiDAR point elevation and DEMs. Average plot GPS elevation differences ranged from 0.24 (SD 1.55 to 2.82 m (SD 4.58 for the nearest LiDAR point, and from 0.27 (SD 2.33 to 2.69 m (SD 5.06 for LiDAR DEMs. We believe that our efforts represent one of the most robust studies of LiDAR measurement errors available in published literature. The relatively small measurement differences that we found between LiDAR elevations and our most reliable field-based method of elevations, the digital total station, demonstrate the potential for LiDAR in forestry and natural resource applications.

  15. ¿Es posible matizar el individualismo de John Locke?

    Directory of Open Access Journals (Sweden)

    Diego A. Fernández Peychaux

    2011-12-01

    Full Text Available El interrogante del que este artículo pretende dar cuenta es si el individualismo de John Locke responde a la radicalidad con la que la corriente de interpretación más difundida intenta caracterizarlo. La conclusión que se alcanza luego de una amplia presentación de pruebas textuales, es que la necesaria matización del individualismo se deriva de la insistencia del autor en justificar el origen divino de los derechos y deberes. De este modo, en la medida en que se niegue que los hombres disponen de un derecho irrefrenable a seguir su deseo de autopreservación, es posible concluir que el Estado no existe para resguardar esos presuntos derechos individuales, sino para restaurar la ley de naturaleza que ya no sirve, como debería, para determinar los derechos y deberes de los hombres.

  16. Processing LiDAR Data to Predict Natural Hazards

    Science.gov (United States)

    Fairweather, Ian; Crabtree, Robert; Hager, Stacey

    2008-01-01

    ELF-Base and ELF-Hazards (wherein 'ELF' signifies 'Extract LiDAR Features' and 'LiDAR' signifies 'light detection and ranging') are developmental software modules for processing remote-sensing LiDAR data to identify past natural hazards (principally, landslides) and predict future ones. ELF-Base processes raw LiDAR data, including LiDAR intensity data that are often ignored in other software, to create digital terrain models (DTMs) and digital feature models (DFMs) with sub-meter accuracy. ELF-Hazards fuses raw LiDAR data, data from multispectral and hyperspectral optical images, and DTMs and DFMs generated by ELF-Base to generate hazard risk maps. Advanced algorithms in these software modules include line-enhancement and edge-detection algorithms, surface-characterization algorithms, and algorithms that implement innovative data-fusion techniques. The line-extraction and edge-detection algorithms enable users to locate such features as faults and landslide headwall scarps. Also implemented in this software are improved methodologies for identification and mapping of past landslide events by use of (1) accurate, ELF-derived surface characterizations and (2) three LiDAR/optical-data-fusion techniques: post-classification data fusion, maximum-likelihood estimation modeling, and hierarchical within-class discrimination. This software is expected to enable faster, more accurate forecasting of natural hazards than has previously been possible.

  17. An Interactive Segmentation Method of LiDAR Data

    OpenAIRE

    Wen-Hui Li; Hong-Yin Ni; Hui-Ying Li; Ying Wang; Bo Fu; Yi-Feng Lin; Pei-Xun Liu

    2013-01-01

    In order to alleviate the problems inherent of automatic segmentation of LiDAR data, an interactive graph-cut segmentation method of LiDAR data is proposed. Firstly, the research background and the basic conceptions of the interactive graph-cut algorithm are introduced. Secondly, by analyzing the characteristics of LiDAR data, four-dimensional feature vectors are extracted, which as the graph-cut algorithm's input. Thirdly, the optimal parameter is estimated according to a new Sample-fitting ...

  18. Georeferenced LiDAR 3D Vine Plantation Map Generation

    OpenAIRE

    Meritxell Queraltó; Jordi Llop; Emilio Gil; Jordi Llorens

    2011-01-01

    The use of electronic devices for canopy characterization has recently been widely discussed. Among such devices, LiDAR sensors appear to be the most accurate and precise. Information obtained with LiDAR sensors during reading while driving a tractor along a crop row can be managed and transformed into canopy density maps by evaluating the frequency of LiDAR returns. This paper describes a proposed methodology to obtain a georeferenced canopy map by combining the information obtained with LiD...

  19. Mapping tree genera using discrete LiDAR and geometric tree metrics / Mapeo del género de árboles usando LiDAR y métricas geométricas para árboles

    Scientific Electronic Library Online (English)

    Connie, Ko; Tarmo K, Remmel; Gunho, Sohn.

    Full Text Available SciELO Chile | Language: English Abstract in spanish Los mapas de géneros de árboles son útiles para el inventario forestal, planificación urbana y el mantenimiento de la infraestructura de líneas de transmisión. Se presenta un estudio de caso de uso de datos LiDAR de alta densidad para el mapeo de géneros de árboles a lo largo del derecho de paso (RO [...] W) de un corredor de línea de transmisión. El objetivo de la investigación fue identificar árboles individuales que mostraban o poseían una amenaza potencial a la infraestructura de la línea de transmisión. Mediante el uso de mapas tridimensionales de LiDAR se derivaron métricas de árboles que están relacionadas con la geometría de éstos (formas del árbol). Por ejemplo, la dirección del crecimiento dominante de los árboles es útil para identificar árboles que crecen inclinados hacia las líneas de transmisión. También se derivaron otras métricas geométricas que son útiles para determinar los géneros de los árboles, tales como altura, forma de la copa, tamaño y estructura de ramas. El área de estudio se ubicó al norte de Thessalon, Ontario, Canadá, a lo largo de los principales corredores de ROW y en los bosques aledaños. Los atributos geométricos usados para la clasificación de los géneros fueron categorizados en cinco amplias clases: 1) líneas, 2) agrupamiento, 3) volúmenes, 4) amortiguamiento en 3D de puntos, y 5) forma general del árbol que provee parámetros como una entrada para el clasificador forestal aleatorio. Abstract in english Maps of tree genera are useful in applications including forest inventory, urban planning, and the maintenance of utility transmission line infrastructure. We present a case study of using high density airborne LiDAR data for tree genera mapping along the right of way (ROW) of a utility transmission [...] line corridor. Our goal was to identify single trees that showed or posed potential threats to transmission line infrastructure. Using the three dimensional mapping capability of LiDAR, we derived tree metrics that are related to the geometry of the trees (tree forms). For example, the dominant growth direction of trees is useful in identifying trees that are leaning towards transmission lines. We also derived other geometric indices that are useful in determining tree genera; these metrics included their height, crown shape, size, and branching structures. Our pilot study was situated north of Thessalon, Ontario, Canada along a major utility corridor ROW and surrounding woodlots. The geometric features used for general classification could be categorized into five broad categories related to: 1) lines, 2) clusters, 3) volumes, 4) 3D buffers of points, and 5) overall tree shape that provide parameters as an input for the Random Forest classifier.

  20. Mapping tree genera using discrete LiDAR and geometric tree metrics Mapeo del género de árboles usando LiDAR y métricas geométricas para árboles

    Directory of Open Access Journals (Sweden)

    Connie Ko

    2012-01-01

    Full Text Available Maps of tree genera are useful in applications including forest inventory, urban planning, and the maintenance of utility transmission line infrastructure. We present a case study of using high density airborne LiDAR data for tree genera mapping along the right of way (ROW of a utility transmission line corridor. Our goal was to identify single trees that showed or posed potential threats to transmission line infrastructure. Using the three dimensional mapping capability of LiDAR, we derived tree metrics that are related to the geometry of the trees (tree forms. For example, the dominant growth direction of trees is useful in identifying trees that are leaning towards transmission lines. We also derived other geometric indices that are useful in determining tree genera; these metrics included their height, crown shape, size, and branching structures. Our pilot study was situated north of Thessalon, Ontario, Canada along a major utility corridor ROW and surrounding woodlots. The geometric features used for general classification could be categorized into five broad categories related to: 1 lines, 2 clusters, 3 volumes, 4 3D buffers of points, and 5 overall tree shape that provide parameters as an input for the Random Forest classifier.Los mapas de géneros de árboles son útiles para el inventario forestal, planificación urbana y el mantenimiento de la infraestructura de líneas de transmisión. Se presenta un estudio de caso de uso de datos LiDAR de alta densidad para el mapeo de géneros de árboles a lo largo del derecho de paso (ROW de un corredor de línea de transmisión. El objetivo de la investigación fue identificar árboles individuales que mostraban o poseían una amenaza potencial a la infraestructura de la línea de transmisión. Mediante el uso de mapas tridimensionales de LiDAR se derivaron métricas de árboles que están relacionadas con la geometría de éstos (formas del árbol. Por ejemplo, la dirección del crecimiento dominante de los árboles es útil para identificar árboles que crecen inclinados hacia las líneas de transmisión. También se derivaron otras métricas geométricas que son útiles para determinar los géneros de los árboles, tales como altura, forma de la copa, tamaño y estructura de ramas. El área de estudio se ubicó al norte de Thessalon, Ontario, Canadá, a lo largo de los principales corredores de ROW y en los bosques aledaños. Los atributos geométricos usados para la clasificación de los géneros fueron categorizados en cinco amplias clases: 1 líneas, 2 agrupamiento, 3 volúmenes, 4 amortiguamiento en 3D de puntos, y 5 forma general del árbol que provee parámetros como una entrada para el clasificador forestal aleatorio.

  1. Alternative Methodologies for LiDAR System Calibration

    OpenAIRE

    Jacky Chow; Ana Paula Kersting; Ki In Bang; Ayman Habib

    2010-01-01

    Over the last few years, LiDAR has become a popular technology for the direct acquisition of topographic information. In spite of the increasing utilization of this technology in several applications, its accuracy potential has not been fully explored. Most of current LiDAR calibration techniques are based on empirical and proprietary procedures that demand the system’s raw measurements, which may not be always available to the end-user. As a result, we can still observe systematic discrepa...

  2. High Fidelity DEM Generation Based on LiDAR Data

    OpenAIRE

    Xudong Lai; Zujie Han

    2012-01-01

    With favorable penetrability to vegetation, LiDAR data is an important data source to generate high precision DEM for reconnaissance and design of railway. To avoid the limitation of the LiDAR data-processing in keeping terrain feature and to satisfy the demand of the reconnaissance and design, this paper presents a high fidelity DEM production method, which successively uses the specialized software and the variety photogrammetry technology. The large scale results of production have proved ...

  3. Assessing understory development in forest plantations using laser imaging detection and ranging (LiDAR) / Evaluación del desarrollo del sotobosque en plantaciones forestales mediante LiDAR

    Scientific Electronic Library Online (English)

    JAIME, HERNÁNDEZ; M. PAZ, ACUÑA; PATRICIO, CORVALÁN; JAVIER A, SIMONETTI.

    2013-12-01

    Full Text Available SciELO Chile | Language: English Abstract in spanish Las plantaciones forestales deberían ser manejadas de forma que conserven biodiversidad al tiempo que provean bienes y servicios. Este es un desafío significativo pues las plantaciones tienden a reducir la riqueza de especies nativas. La presencia de un sotobosque desarrollado incrementa el valor de [...] las plantaciones como hábitat para la fauna nativa. En este trabajo desarrollamos un método sencillo para evaluar la disponibilidad de sotobosque en plantaciones forestales empleando imágenes LiDAR y RGB de alta resolución. En base a datos de campo, LiDAR e imágenes aéreas para rodales de Pinus radiata en Chile central, el modelo digital de copa (DCM), obtenido de sustraer el modelo digital de terreno (DTM) del modelo digital de superficie (DSM) es un predictor más confiable del desarrollo del sotobosque que variables como la pendiente del terreno, la exposición, la edad de la plantación y la altura del dosel de la plantación en situaciones en las cuales en dosel superior no está completamente cerrado. La correlación entre DCM y el sotobosque sin embargo decrece con la altura del dosel de la plantación, lo que hace de DCM un estimador conservador del desarrollo del sotobosque. El uso de DCM permitirá una evaluación rápida y costo/efectiva de la disponibilidad de hábitat para fauna nativa en plantaciones forestales. Abstract in english Forestry plantations are expected to be managed in ways to conserve biodiversity while producing goods and services. This goal implies a significant challenge as plantations tend to reduce species richness. The presence of well developed understory enhances the value of plantations as habitat for na [...] tive fauna. Here, we develop a straightforward method to assess the availability of understory in forestry stands using laser imaging detection and ranging (LiDAR) data and aerial RGB high resolution images. Based on field and airborne acquired data for Pinus radiata stands in central Chile, the digital crown model (DCM), derived from the subtraction of the digital terrain model (DTM) from the digital surface model (DSM) is a more reliable predictor of understory height that variables like terrain slope, aspect, plantation age and canopy height in forests and plantations which have not complete closed canopy. The correlation between DCM and understory though decreases while the actual height of the plantation canopy increases, rendering DCM a conservative estimate of understory development. The use of DCM will allow a fast and cost/effective estimate of habitat suitability in forestry plantations.

  4. Addressing Climate-Related Challenges and Information Needs in Africa

    Science.gov (United States)

    Shongwe, M. E.; Pirani, Anna; Bekele, Seleshi

    2014-06-01

    The Africa Climate Conference 2013 (ACC-2013), which was organized by the World Climate Research Programme, the African Climate Policy Center of the United Nations Economic Commission for Africa, and the University of Dar es Salaam, brought together more than 300 participants, including decision makers, representatives of research funding agencies, scientists from various disciplines, and practitioners from Africa and around the globe.

  5. Access, Use and Perceptions of Teachers and Students towards Mobile Phones as a Tool for Teaching and Learning in Tanzania

    Science.gov (United States)

    Kafyulilo, Ayoub

    2014-01-01

    This study explored the access, use and perceptions of teachers and students towards mobile phones as a tool for facilitating teaching and learning beyond the classroom walls. A total of 29 pre-service teachers and four college instructors from Dar es salaam University College of Education (DUCE) as well as 12 in-service teachers and 40 students…

  6. Codeswitching and the Exclusivity of Social Identities: Some Data from Campus Kiswahili.

    Science.gov (United States)

    Blommaert, Jan

    1992-01-01

    The macro-dimension of code switching is examined as observed in a sociolect of Swahili used by academic staff from the University of Dar es Salaam. It is argued that the specific sociohistoric background of Tanzanian society accounts for the social valency of Campus Kiswahili. (Author/LB)

  7. An HIV/AIDS Knowledge Scale for Adolescents: Item Response Theory Analyses Based on Data from a Study in South Africa and Tanzania

    Science.gov (United States)

    Aaro, Leif E.; Breivik, Kyrre; Klepp, Knut-Inge; Kaaya, Sylvia; Onya, Hans E.; Wubs, Annegreet; Helleve, Arnfinn; Flisher, Alan J.

    2011-01-01

    A 14-item human immunodeficiency virus/acquired immunodeficiency syndrome knowledge scale was used among school students in 80 schools in 3 sites in Sub-Saharan Africa (Cape Town and Mankweng, South Africa, and Dar es Salaam, Tanzania). For each item, an incorrect or don't know response was coded as 0 and correct response as 1. Exploratory factor…

  8. Extraction of Mangrove Biophysical Parameters Using Airborne LiDAR

    Directory of Open Access Journals (Sweden)

    Poonsak Miphokasap

    2013-04-01

    Full Text Available Tree parameter determinations using airborne Light Detection and Ranging (LiDAR have been conducted in many forest types, including coniferous, boreal, and deciduous. However, there are only a few scientific articles discussing the application of LiDAR to mangrove biophysical parameter extraction at an individual tree level. The main objective of this study was to investigate the potential of using LiDAR data to estimate the biophysical parameters of mangrove trees at an individual tree scale. The Variable Window Filtering (VWF and Inverse Watershed Segmentation (IWS methods were investigated by comparing their performance in individual tree detection and in deriving tree position, crown diameter, and tree height using the LiDAR-derived Canopy Height Model (CHM. The results demonstrated that each method performed well in mangrove forests with a low percentage of crown overlap conditions. The VWF method yielded a slightly higher accuracy for mangrove parameter extractions from LiDAR data compared with the IWS method. This is because the VWF method uses an adaptive circular filtering window size based on an allometric relationship. As a result of the VWF method, the position measurements of individual tree indicated a mean distance error value of 1.10 m. The individual tree detection showed a kappa coefficient of agreement (K value of 0.78. The estimation of crown diameter produced a coefficient of determination (R2 value of 0.75, a Root Mean Square Error of the Estimate (RMSE value of 1.65 m, and a Relative Error (RE value of 19.7%. Tree height determination from LiDAR yielded an R2 value of 0.80, an RMSE value of 1.42 m, and an RE value of 19.2%. However, there are some limitations in the mangrove parameters derived from LiDAR. The results indicated that an increase in the percentage of crown overlap (COL results in an accuracy decrease of the mangrove parameters extracted from the LiDAR-derived CHM, particularly for crown measurements. In this study, the accuracy of LiDAR-derived biophysical parameters in mangrove forests using the VWF and IWS methods is lower than in coniferous, boreal, pine, and deciduous forests. An adaptive allometric equation that is specific for the level of tree density and percentage of crown overlap is a solution for improving the predictive accuracy of the VWF method.

  9. LiDAR error estimation with WAsP engineering

    International Nuclear Information System (INIS)

    The LiDAR measurements, vertical wind profile in any height between 10 to 150m, are based on assumption that the measured wind is a product of a homogenous wind. In reality there are many factors affecting the wind on each measurement point which the terrain plays the main role. To model LiDAR measurements and predict possible error in different wind directions for a certain terrain we have analyzed two experiment data sets from Greece. In both sites LiDAR and met, mast data have been collected and the same conditions are simulated with RisOe/DTU software, WAsP Engineering 2.0. Finally measurement data is compared with the model results. The model results are acceptable and very close for one site while the more complex one is returning higher errors at higher positions and in some wind directions

  10. Raster Vs. Point Cloud LiDAR Data Classification

    Science.gov (United States)

    El-Ashmawy, N.; Shaker, A.

    2014-09-01

    Airborne Laser Scanning systems with light detection and ranging (LiDAR) technology is one of the fast and accurate 3D point data acquisition techniques. Generating accurate digital terrain and/or surface models (DTM/DSM) is the main application of collecting LiDAR range data. Recently, LiDAR range and intensity data have been used for land cover classification applications. Data range and Intensity, (strength of the backscattered signals measured by the LiDAR systems), are affected by the flying height, the ground elevation, scanning angle and the physical characteristics of the objects surface. These effects may lead to uneven distribution of point cloud or some gaps that may affect the classification process. Researchers have investigated the conversion of LiDAR range point data to raster image for terrain modelling. Interpolation techniques have been used to achieve the best representation of surfaces, and to fill the gaps between the LiDAR footprints. Interpolation methods are also investigated to generate LiDAR range and intensity image data for land cover classification applications. In this paper, different approach has been followed to classifying the LiDAR data (range and intensity) for land cover mapping. The methodology relies on the classification of the point cloud data based on their range and intensity and then converted the classified points into raster image. The gaps in the data are filled based on the classes of the nearest neighbour. Land cover maps are produced using two approaches using: (a) the conventional raster image data based on point interpolation; and (b) the proposed point data classification. A study area covering an urban district in Burnaby, British Colombia, Canada, is selected to compare the results of the two approaches. Five different land cover classes can be distinguished in that area: buildings, roads and parking areas, trees, low vegetation (grass), and bare soil. The results show that an improvement of around 10 % in the classification results can be achieved by using the proposed approach.

  11. Forest Structural Parameter Extraction Using Terrestrial LiDAR

    Science.gov (United States)

    Huang, H.; Gong, P.; Cheng, X.; Wang, J.

    2008-12-01

    Accurate forest structural parameters are crucial to forest inventory, carbon cycling and wildlife habit modeling. LiDAR (Light Detection and Ranging) is a novel technique to measure forest structural parameters. In this paper we describe a pilot research to extract forest structural parameters, such as tree height, DBH (diameter at breast height), and the position of each individual tree using a terrestrial LiDAR. The raw data were acquired using a terrestrial LiDAR (Riegel, LMS-Z360i), and vertical and horizontal scanning were done to obtain point cloud of the whole scene. An ICP (Iterative Closet Point) algorithm was introduced to get the transformation matrix of each range image and to mosaic multiple range images together. Based on the whole data sets, a variable scale and threshold filtering method was used to classify ground from forest. Meanwhile, a DEM (Digital Elevation Model) and a CHM (Canopy Height Model) were generated from the classified point cloud. A stem detection algorithm was used to extract the location of individual trees. A slice above 1.3 m from the ground was extracted and rasterized. A circle fitting algorithm was used to retrieve the DBH based on the rasterized grid. Tree heights were calculated using the height difference between the vertex and nadir. Our methods and results confirm that terrestrial LiDAR can provide nondestructive, high- resolution and automatic determination of parameters required in forest inventory.

  12. Modeling low-height vegetation with airborne LiDAR

    Science.gov (United States)

    Low-height vegetation, common in semiarid regions, is difficult to characterize with LiDAR (Light Detection and Ranging) due to similarities, in time and space, of the point returns of vegetation and ground. Other complications may occur due to the low-height vegetation structural characteristics a...

  13. Los vínculos de los que la familia es capaz

    Directory of Open Access Journals (Sweden)

    Gisela Daza Navarrete

    1999-10-01

    Full Text Available La familia es sujeto y objeto de transformaciones entretejidas en el curso de los acontecimientos que se suceden en la producción económica y social en el capitalismo occidental. Sin embargo, la posición periférica que ocupamos en él produce expresiones susceptibles de ser consideradas como constitutivas de nuestra singularidad, bien sea por el matiz específico de su manifestación, bien sea por su capacidad para ejercer resistencia al curso impuesto por la tendencia general. Este texto, prosiguiendo el acontecer de los cambios de lo social, describe la afectación de los vínculos familiares en la propagación de la normalización, en la generación de los padres y de sus hijos, para dar paso, más tarde, a una serie de prácticas afianzadas en una nueva expresión del poder, el control, cuya manifestaciones más densas tienen lugar con la generación de los nietos.

  14. Extraction of Urban Power Lines from Vehicle-Borne LiDAR Data

    OpenAIRE

    Liang Cheng; Lihua Tong; Yu Wang,; Manchun Li

    2014-01-01

    Airborne LiDAR has been traditionally used for power line cruising. Nevertheless, data acquisition with airborne LiDAR is constrained by the complex environments in urban areas as well as the multiple parallel line structures on the same power line tower, which means it is not directly applicable to the extraction of urban power lines. Vehicle-borne LiDAR system has its advantages upon airborne LiDAR and this paper tries to utilize vehicle-borne LiDAR data for the extraction of urban power li...

  15. Portadores de VIH/SIDA e HCC: dar voz a relatos de sofrimento

    Scientific Electronic Library Online (English)

    Sofia Santanna, Gandra; Zélia, Teixeira.

    Full Text Available SciELO Portugal | Language: Portuguese Abstract in portuguese É inquestionável que o diagnóstico de se ser portador de uma doença crónica alberga muitas implicações. Contudo, o diagnóstico de Vírus da Imunodeficiência Humana (VIH)/ Síndrome da Imunodeficiência Adquirida (SIDA) tem um impacto particular na vida do portador, e nas relações com as pessoas para si [...] significativas, nomeadamente quando consideramos o estigma a ele associado. O contacto com estes sujeitos fez-nos perceber que mesmo quando estes são internados por complicações relacionadas com a hepatite, culpabilizam o VIH e não a Hepatite C Crónica (HCC). A principal implicação psicológica é a ansiedade, encontrada em todos os sujeitos, o que nos surpreendeu dado que a literatura coloca a depressão como sintoma psicológico mais frequentemente associado à infecção pelo VIH/SIDA, não se tendo encontrado idên­tica constatação em relação à HCC. A metodologia qualitativa utilizada visou dar a este trabalho um contorno exploratório, descritivo e analítico das experiências e vivências de 17 indivíduos portadores de VIH/SIDA e de HCC, a quem tentamos dar voz, na expressão do seu sofrimento físico, psicológico e social. Abstract in spanish Es incuestionable que serse portador de una enfermedad crónica engloba muchas implicaciones. Sin embargo, el diagnóstico del virus de la inmunodeficiencia humana (VIH) / Síndrome de inmunodeficiencia adquirida (SIDA) tiene un impacto particular en la vida del portador y en las relaciones con las per [...] sonas significativas, sobre todo considerando el estigma que está asociado a él. El contacto con estos sujetos permitió que entendiéramos que mismo cuando estos son internados debido a complicaciones relacionadas con la hepatitis, culpabilizan el VIH e no la hepatitis C Crónica (HCC). La principal implicación psicológica es la ansiedad, percibida en todos los sujetos, facto que nos sorprendió ya que la literatura coloca la depresión como síntoma psicológico más frecuentemente asociado a la infección por vía VIH/SIDA, no se verificando idéntica constatación relativamente a la HCC. La metodología cualitativa utilizada se fijó en dar a este trabajo un carácter exploratorio, descriptivo y analítico de las experiencias y vivencias de 17 sujetos portadores de VIH/SIDA y de HCC, a los cuales intentamos dar voz, en la expresión de su sufrimiento físico, psicológico y social. Abstract in english It is undeniable that being diagnosed with a chronic disease sets numerous implications. However, the diagnosis of Human Immunodeficiency Virus (HIV)/ Acquired Immune Deficiency Syndrome (AIDS) seems to have a particular impact on the person’s life and relationships, especially if considering the st [...] igma associated to it. Being in touch with these individuals made us realize that, even when hospitalized due to complications related to hepatitis, they tend to blame the HIV instead of the Chronic Hepatitis C (CHC). The main psychological condition found in all patients was, unexpec­tedly, anxiety, given the fact that literature places depression as the most frequent psychological symptom associated to HIV/AIDS, not having found any similar information relating to CHC. The qualitative methodology we applied meant to give this article an exploratory, descriptive and analytical outline of the experiences of 17 HIV/AIDS and CHC infected, to whom we gave voice to express their physical, psychological and social anguish.

  16. LiDAR-Derived DEM and Raw Height Comparisons along Profile Corridor Gradients within a Forest

    Directory of Open Access Journals (Sweden)

    Michael G. Wing

    2013-04-01

    Full Text Available We compared field based and airborne LiDAR-derived profile corridor measurements across forest canopy types and terrain ranging from 37% to 49% slope. Both LiDAR-derived DEM and raw LiDAR point elevations were compared to field data. Primary objectives included examining whether canopy type or terrain slope influenced LiDAR-derived profile measurements. A secondary objective included comparing cable logging payloads based on field measured profile elevations to payloads based on LiDAR-derived elevations. Average RMSE elevation errors were slightly lower for profile point to LiDAR DEM values (0.43 m than profile point to nearest LiDAR elevation point (0.49 m with differences being larger when sites within forest clearings were removed from analysis. No statistically significant relationship existed between field measured ground slopes and associated profile point and LiDAR DEM elevation differences but a mild correlation existed when LiDAR raw point elevation differences were compared. Our payload analysis determined the limiting payload distance and had consistent results across study sites. The DEM-based profile outperformed the nearest point profile by 5% on average. Results suggest that forest analysts should consider using the nearest LiDAR DEM value rather than the nearest LiDAR point elevation for terrain heights at discrete locations, particularly when forest canopy occludes locations of interest.

  17. Estatinas en insuficiencia cardíaca: "dar o no dar" / Statins in heart failure: "to give or not to give" / Estatinas na insuficiência cardíaca: "dar ou não dar"

    Scientific Electronic Library Online (English)

    Carlos Andrés, León; Silvia, Moro.

    2007-12-01

    Full Text Available SciELO Argentina | Language: Spanish Abstract in portuguese Pacientes com níveis de colesterol aumentados representam uma população em risco de sofrer eventos cardiovasculares e morte por doença vascular. As estatinas demonstraram ser efetivas em reduzir o colesterol e, portanto diminuir os eventos cardiovasculares em pacientes com doença arterial coronária [...] ou com alto risco de desenvolvêlas. Na insuficiência cardíaca crônica (ICC), baixos níveis de colesterol estão associados com o aumento da mortalidade. Este fenômeno, conhecido como epidemiologia inversa não se apresenta somente em IC, senão também em doenças críticas dos idoso. Uma possível explicação é a hipótese da endotoxina, a qual se refere que o colesterol cumpre uma função de "purificador" das endotoxinas.As estatinas não só diminuem o colesterol, mas também têm efeitos pleiotrópicos, como antiinflamatórios e melhoria da função endotelial. Faz-se necessário uma revisão nos mecanismos farmacológicos dos efeitos do tratamento com estatinas, para tratar de conciliar estes efeitos contraditórios. Neste trabalho revisaremos os efeitos prejudiciais e benéficos do tratamento com estatinas em modelos animais e em humanos com ICC. Faz-se necessário uma maior investigação no modelo de ICC em humanos. Abstract in spanish Pacientes con niveles de colesterol aumentados representan una población en riesgo de sufrir eventos cardiovasculares y muerte por enfermedad vascular. Las estatinas han demostrado ser efectivas en reducir el colesterol y por lo tanto disminuir los eventos cardiovasculares en pacientes con enfermeda [...] d arterial coronaria o con alto riesgo de desarrollarla. En insuficiencia cardíaca crónica (ICC), bajos niveles de colesterol están asociados con aumento de la mortalidad. Este fenómeno, conocido como epidemiología reversa no se presenta sólo en ICC, sino también en enfermedades críticas del anciano. Una posible explicación es la hipótesis de la endotoxina, la cual refiere que el colesterol cumple una función de"purificador" de las endotoxinas. Las estatinas no sólo disminuyen el colesterol, también tienen efectos pleiotrópicos, como antiinflamatorios y mejoría de la función endotelial. Se hace necesario revisar los mecanismos farmacológicos de los efectos del tratamiento con estatinas, para tratar de conciliar estos efectos contradictorios. En este trabajo revisaremos los efectos dañinos y beneficiosos del tratamiento con estatinas en modelos animales y en humanos con ICC. Se hace necesaria una mayor investigación en el modelo de ICC en humanos. Abstract in english Patients with increased cholesterol levels are at increased risk to experience cardiovascular events and to die from vascular disease. Statins have been proven to effectively reduce cholesterol levels and subsequently reduce cardiovascular events in patients with coronary artery disease or at increa [...] sed risk to develop coronary artery disease. However, in patients with chronic heart failure (CHF), low levels of cholesterol are related to increased mortality. This phenomenon of reverse epidemiology is not unique to CHF, but also exists in other critical disease and in the elderly in general as well. An important rationale has been provided by the endotoxin hypothesis, which suggests that cholesterol has an important scavenger function regarding harmful en dotoxins. Indeed, these lines of evidence predict a harmful effect of statin treatment in patients with CHF. However, statins not only lower cholesterol, but also have been reported to exhibit pleiotropic effects, including reduction of inflammation and improvement of endothelial function. In order to reconcile these contradictory lines of evidence, it is necessary to examine the pharmacological mechanisms of effects of statin treatment. In this review, we provide the available lines of evidence in animal models and humans predicting both harmful and beneficial effects of statin treatment in CHF. We emphasize the importance of additional research spe

  18. Graph-based filtering of urban LiDAR data

    Science.gov (United States)

    Belkhouche, Yassine; Buckles, Bill; Duraisamy, Prakash; Alam, Mohammad S.

    2014-04-01

    A graph-based approach for modeling and solving the LiDAR filtering problem in urban areas is established. Our method consists of three steps. In the first step we construct a graph-based representation of the LiDAR data, Delaunay triangulation or the KNN graph can be used in this step. An algorithm is introduced to label the edges of this graph. In this second step, we defined criteria to eliminate some of the graph edges, then we used a connected components algorithm to separate the graph representation into different components. Finally, these components are classified into terrain or objects. Different datasets with different characteristics have been used to analyze the performance of our method.

  19. Monitoring coastal change using terrestrial LiDAR

    OpenAIRE

    Hobbs, P.; Gibson, A.; Jones, L.; Poulton, C.; Jenkins, G.; Pearson, S.; Freeborough, K.

    2010-01-01

    The paper describes recent applications by the British Geological Survey (BGS) of the technique of mobile terrestrial Light Detection And Ranging (LiDAR) surveying to monitor various geomorphological changes on English coasts and estuaries. These include cliff recession, landslides and flood defences, and are usually sited at remote locations undergoing dynamic processes with no fixed reference points. Advantages, disadvantages and some practical problems are discussed. The role of GPS in las...

  20. Rapid topographic and bathymetric reconnaissance using airborne LiDAR

    Science.gov (United States)

    Axelsson, Andreas

    2010-10-01

    Today airborne LiDAR (Light Detection And Ranging) systems has gained acceptance as a powerful tool to rapidly collect invaluable information to assess the impact from either natural disasters, such as hurricanes, earthquakes and flooding, or human inflicted disasters such as terrorist/enemy activities. Where satellite based imagery provides an excellent tool to remotely detect changes in the environment, the LiDAR systems, being active remote sensors, provide an unsurpassed method to quantify these changes. The strength of the active laser based systems is especially evident in areas covered by occluding vegetation or in the shallow coastal zone as the laser can penetrate the vegetation or water body to unveil what is below. The purpose of this paper is to address the task to survey complex areas with help of the state-of-the-art airborne LiDAR systems and also discuss scenarios where the method is used today and where it may be used tomorrow. Regardless if it is a post-hurricane survey or a preparation stage for a landing operation in unchartered waters, it is today possible to collect, process and present a dense 3D model of the area of interest within just a few hours from deployment. By utilizing the advancement in processing power and wireless network capabilities real-time presentation would be feasible.

  1. Quantifying Ladder Fuels: A New Approach Using LiDAR

    Directory of Open Access Journals (Sweden)

    Heather A. Kramer

    2014-06-01

    Full Text Available We investigated the relationship between LiDAR and ladder fuels in the northern Sierra Nevada, California USA. Ladder fuels are often targeted in hazardous fuel reduction treatments due to their role in propagating fire from the forest floor to tree crowns. Despite their importance, ladder fuels are difficult to quantify. One common approach is to calculate canopy base height, but this has many potential sources of error. LiDAR may be a way forward to better characterize ladder fuels, but has only been used to address this question peripherally and in only a few instances. After establishing that landscape fuel treatments reduced canopy and ladder fuels at our site, we tested which LiDAR-derived metrics best differentiated treated from untreated areas. The percent cover between 2 and 4 m had the most explanatory power to distinguish treated from untreated pixels across a range of spatial scales. When compared to independent plot-based measures of ladder fuel classes, this metric differentiated between high and low levels of ladder fuels. These findings point to several immediate applications for land managers and suggest new avenues of study that could lead to possible improvements in the way that we model wildfire behavior across forested landscapes in the US.

  2. Measurement procedures for characterization of wind turbine wakes with scanning Doppler wind LiDARs

    OpenAIRE

    Iungo, G. V.; Porte?-agel, F.

    2013-01-01

    The wake flow produced from an Enercon E-70 wind turbine is investigated through three scanning Doppler wind LiDARs. One LiDAR is deployed upwind to characterize the incoming wind, while the other two LiDARs are located downstream to carry out wake measurements. The main challenge in performing measurements of wind turbine wakes is represented by the varying wind conditions, and by the consequent adjustments of the turbine yaw angle needed to maximize power production. Co...

  3. Using Satellite and Airborne LiDAR to Model Woodpecker Habitat Occupancy at the Landscape Scale

    OpenAIRE

    Vierling, Lee A.; Vierling, Kerri T.; Adam, Patrick; Hudak, Andrew T.

    2013-01-01

    Incorporating vertical vegetation structure into models of animal distributions can improve understanding of the patterns and processes governing habitat selection. LiDAR can provide such structural information, but these data are typically collected via aircraft and thus are limited in spatial extent. Our objective was to explore the utility of satellite-based LiDAR data from the Geoscience Laser Altimeter System (GLAS) relative to airborne-based LiDAR to model the north Idaho breeding distr...

  4. Multipath Estimation in Urban Environments from Joint GNSS Receivers and LiDAR Sensors

    OpenAIRE

    Ferna?ndez, Antonio J.; Fabio Dovis; David de Castro; Xin Chen; Khurram Ali

    2012-01-01

    In this paper, multipath error on Global Navigation Satellite System (GNSS) signals in urban environments is characterized with the help of Light Detection and Ranging (LiDAR) measurements. For this purpose, LiDAR equipment and Global Positioning System (GPS) receiver implementing a multipath estimating architecture were used to collect data in an urban environment. This paper demonstrates how GPS and LiDAR measurements can be jointly used to model the environment and obtain robust receivers....

  5. LA DIETA MEDITERRÁNEA: ES CARDIOPROTECTIVA?

    Directory of Open Access Journals (Sweden)

    Alfredo Arredondo Bruce

    2007-01-01

    Full Text Available La enfermedad coronaria es una de las principales causas de morbilidad y mortalidad en USA, la intervención de la dieta es una línea primaria en el tratamiento y prevención de la misma. El aumento de la evidencia científica muestra que la tradicional dieta mediterránea puede reducir los riesgos de una enfermedad cardiovascular, los beneficios cardiovasculares de esta dieta superan lo de las dietas de baja grasa prescriptas clásicamente, la carga de las enfermedades cardiovasculares es enorme, y los aportes nutricionales que puedan optimizar la salida cardiovascular son esenciales. Las evidencias clínicas apoyan el role de la dieta mediterránea en la salud cardiovascular, presentándose con mucho énfasis los efectos fisiológicos de los ácidos grasos omega -3. Se discuten las implicaciones en la práctica clínica y se enfocan futuras investigaciones.

  6. ¿Es moderno el urbanismo latinoamericano?

    Directory of Open Access Journals (Sweden)

    Elizabeth Valencia

    2013-01-01

    Full Text Available El urbanismo latinoamericano no es moderno funda­ mentalmente porque la noción de teoría con la cual piensa y construye la ciudad no es el concepto moderno de teoría. En el modelo de la economía neoliberal capitalista como marco para la reflexión urbana sobre América Latina, lo que predomina es el desinterés por la teoría y el combate a su concepción moderna desde el pragmatismo, el posmodernismo y los estudios cul­turales. Por lo tanto, del urbanismo antimoderno no debemos esperar el interés por el pasado, el futuro, la construcción de comunidad o la inclusión de los pobres, sino una urbanización acorde con los intereses de una minoría en detrimento de los intereses de la mayoría.

  7. Airborne Dual-Wavelength LiDAR Data for Classifying Land Cover

    OpenAIRE

    Cheng-Kai Wang; Yi-Hsing Tseng; Hone-Jay Chu

    2014-01-01

    This study demonstrated the potential of using dual-wavelength airborne light detection and ranging (LiDAR) data to classify land cover. Dual-wavelength LiDAR data were acquired from two airborne LiDAR systems that emitted pulses of light in near-infrared (NIR) and middle-infrared (MIR) lasers. The major features of the LiDAR data, such as surface height, echo width, and dual-wavelength amplitude, were used to represent the characteristics of land cover. Based on the major features of land co...

  8. Applications and benefits of airborne LiDAR technology for transmission line asset management

    Energy Technology Data Exchange (ETDEWEB)

    Ussyshkin, R.V.; Sitar, M. [Optech, Inc., Downsview, ON (Canada)

    2009-07-01

    This presentation discussed applications and benefits of airborne LiDAR technology for transmission line asset management. There are many challenges to satisfy the growing energy demands, such as acquiring rights-of-way for new power lines; maximizing capacity and up-rating of existing lines; and changing detection and monitoring. One option is to use airborne LiDAR technology for power line asset management. Optech's airborne laser terrain mapper (ALTM) is a solution for power line corridor surveys. LiDAR technology for surveying applications include ground-based or airborne laser scanning. The specific topics that were discussed in this presentation were ALTM applications; airborne LiDAR for corridor surveys; advantages of airborne LiDAR; LiDAR workflow; engineering and profile sheets; sag analysis; clearance analysis; vegetation encroachment; and LiDAR data accuracy. The benefits of ALTM for power line surveys were also presented, with particular reference to compactness; installation flexibility; data collection efficiency; and high density of points. Field data for ALTM-Orion was illustrated. It was concluded that Optech's ALTM airborne LiDAR system provides the best solution for power line survey applications. tabs., figs.

  9. Remote sensing of Sonoran Desert vegetation structure and phenology with ground-based LiDAR

    Science.gov (United States)

    Sankey, Joel B.; Munson, Seth M.; Webb, Robert H.; Wallace, Cynthia S.A.; Duran, Cesar M.

    2015-01-01

    Long-term vegetation monitoring efforts have become increasingly important for understanding ecosystem response to global change. Many traditional methods for monitoring can be infrequent and limited in scope. Ground-based LiDAR is one remote sensing method that offers a clear advancement to monitor vegetation dynamics at high spatial and temporal resolution. We determined the effectiveness of LiDAR to detect intra-annual variability in vegetation structure at a long-term Sonoran Desert monitoring plot dominated by cacti, deciduous and evergreen shrubs. Monthly repeat LiDAR scans of perennial plant canopies over the course of one year had high precision. LiDAR measurements of canopy height and area were accurate with respect to total station survey measurements of individual plants. We found an increase in the number of LiDAR vegetation returns following the wet North American Monsoon season. This intra-annual variability in vegetation structure detected by LiDAR was attributable to a drought deciduous shrub Ambrosia deltoidea, whereas the evergreen shrub Larrea tridentata and cactus Opuntia engelmannii had low variability. Benefits of using LiDAR over traditional methods to census desert plants are more rapid, consistent, and cost-effective data acquisition in a high-resolution, 3-dimensional context. We conclude that repeat LiDAR measurements can be an effective method for documenting ecosystem response to desert climatology and drought over short time intervals and at detailed-local spatial scale.

  10. Multipath estimation in urban environments from joint GNSS receivers and LiDAR sensors.

    Science.gov (United States)

    Ali, Khurram; Chen, Xin; Dovis, Fabio; De Castro, David; Fernández, Antonio J

    2012-01-01

    In this paper, multipath error on Global Navigation Satellite System (GNSS) signals in urban environments is characterized with the help of Light Detection and Ranging (LiDAR) measurements. For this purpose, LiDAR equipment and Global Positioning System (GPS) receiver implementing a multipath estimating architecture were used to collect data in an urban environment. This paper demonstrates how GPS and LiDAR measurements can be jointly used to model the environment and obtain robust receivers. Multipath amplitude and delay are estimated by means of LiDAR feature extraction and multipath mitigation architecture. The results show the feasibility of integrating the information provided by LiDAR sensors and GNSS receivers for multipath mitigation. PMID:23202177

  11. Registration of vehicle based panoramic image and LiDAR point cloud

    Science.gov (United States)

    Chen, Changjun; Cao, Liang; Xie, Hong; Zhuo, Xiangyu

    2013-10-01

    Higher quality surface information would be got when data from optical images and LiDAR were integrated, owing to the fact that optical images and LiDAR point cloud have unique characteristics that make them preferable in many applications. While most previous works focus on registration of pinhole perspective cameras to 2D or 3D LiDAR data. In this paper, a method for the registration of vehicle based panoramic image and LiDAR point cloud is proposed. Using the translation among panoramic image, single CCD image, laser scanner and Position and Orientation System (POS) along with the GPS/IMU data, precise co-registration between the panoramic image and the LiDAR point cloud in the world system is achieved. Results are presented under a real world data set collected by a new developed Mobile Mapping System (MMS) integrated with a high resolution panoramic camera, two laser scanners and a POS.

  12. Demonstration of a virtual active hyperspectral LiDAR in automated point cloud classification

    Science.gov (United States)

    Suomalainen, Juha; Hakala, Teemu; Kaartinen, Harri; Räikkönen, Esa; Kaasalainen, Sanna

    2011-09-01

    In this paper, a measurement system for the acquisition of a virtual hyperspectral LiDAR dataset is presented. As commercial hyperspectral LiDARs are not yet available, the system provides a novel type of data for the testing and developing of future hyperspectral LiDAR algorithms. The measurement system consists of two parts: first, backscattered reflectance spectra are collected using a spectrometer and a cutting-edge technology, white-light supercontinuum laser source; second, a commercial monochromatic LiDAR system is used for ranging. A virtual hyperspectral LiDAR dataset is produced by data fusion. Such a dataset was collected on a Norway spruce ( Picea abies) sample. The performance of classification was tested using an experimental hyperspectral algorithm based on a novel combination of the Spectral Correlation Mapper and a region growing algorithm. The classifier was able to automatically distinguish between needles, branches and background, in other words, perform a difficult task using only traditional TLS data.

  13. Canopy wake measurements using multiple scanning wind LiDARs

    Science.gov (United States)

    Markfort, Corey D.; Carbajo Fuertes, Fernando; Valerio Iungo, Giacomo; Stefan, Heinz; Porté-Agel, Fernando

    2014-05-01

    Canopy wakes have been shown, in controlled wind tunnel experiments, to significantly affect the fluxes of momentum, heat and other scalars at the land and water surface over distances of ~O(1 km), see Markfort et al. (EFM, 2013). However, there are currently no measurements of the velocity field downwind of a full-scale forest canopy. Point-based anemometer measurements of wake turbulence provide limited insight into the extent and details of the wake structure, whereas scanning Doppler wind LiDARs can provide information on how the wake evolves in space and varies over time. For the first time, we present measurements of the velocity field in the wake of a tall patch of forest canopy. The patch consists of two uniform rows of 35-meter tall deciduous, plane trees, which border either side of the Allée de Dorigny, near the EPFL campus. The canopy is approximately 250 m long, and it is 35 m wide, along the direction of the wind. A challenge faced while making field measurements is that the wind rarely intersects a canopy normal to the edge. The resulting wake flow may be deflected relative to the mean inflow. Using multiple LiDARs, we measure the evolution of the wake due to an oblique wind blowing over the canopy. One LiDAR is positioned directly downwind of the canopy to measure the flow along the mean wind direction and the other is positioned near the canopy to evaluate the transversal component of the wind and how it varies with downwind distance from the canopy. Preliminary results show that the open trunk space near the base of the canopy results in a surface jet that can be detected just downwind of the canopy and farther downwind dissipates as it mixes with the wake flow above. A time-varying recirculation zone can be detected by the periodic reversal of the velocity vector near the surface, downwind of the canopy. The implications of canopy wakes for measurement and modeling of surface fluxes will be discussed.

  14. Towards a LiDAR based geomorphological database of Sweden

    Science.gov (United States)

    Peterson, Gustaf; Smith, Colby A.

    2013-04-01

    Geomorphological maps can be important for both societal development and scientific research especially with the use of new technology and consideration for the end user's needs. Since 2009, the Swedish mapping agency (Lantmäteriet) has been using airborne light detection and ranging (LiDAR) to create a detailed "bare earth" digital elevation model (DEM) of Sweden. Presently, a LiDAR derived DEM with 2 m horizontal and 0.25 m vertical resolution exist for about half of the country. This data set enables viewing of the landscape in a new more detailed way; landforms never before seen can now be delineated easily in a desktop environment. We are using this DEM to map the geomorphology, bringing into existence a highly detailed, digitial, geomorphologic database and map. While prior geomorphological maps exist for Sweden, the new map being compiled by the Geological Survey of Sweden (SGU) will be the first one to be derived from and presented in an entirely digital format. With the use of GIS technology, it is possible to present a map with different layers and symbology depending on the scale of the area of interest. For example, when looking at a map at a small scale, every moraine within a moraine complex is visible, but when viewed at a larger scale the moraine complex is presented as a single object. The digital presentation allows users to select scale-appropriate geomorphological data to their needs. By coupling other SGU or external databases with the geomorphological database it is possible to produce a wide range of products suitable for a wide range of uses. For example, by adding bedrock or geochemical data to landforms indicative of ice flow direction, a product useful for mineral prospecting is created. Other derivative applications may include groundwater studies or evaluation of geoheritage areas. Regarding scientific applications, the new LiDAR data have enabled mapping of geomorphic landforms in greater detail than previous Swedish maps. In addition to refining the locations and dimensions of previously mapped landforms, features never described before have been brought to light. These features include terminal moraines and cross-cutting glacial lineations. At small scales, these newly mapped landforms show signs of a complex glacial history. On a larger scale, landforms indicative of ice flow direction can be used to create a gridded map of ice flow directions useful for glaciological modelling.

  15. The use of airborne LiDAR data for the analysis of debris flow events in Switzerland

    OpenAIRE

    Scheidl, C.; Rickenmann, D.; Chiari, M.

    2008-01-01

    A methodology of magnitude estimates for debris flow events is described using airborne LiDAR data. Light Detection And Ranging (LiDAR) is a widely used technology to generate digital elevation information. LiDAR data in alpine regions can be obtained by several commercial companies where the automated filtering process is proprietary and varies from companies to companies. This study describes the analysis of geomorphologic changes using digital terrain models derived from commercial LiDAR d...

  16. Toward aerosols LiDAR scattering plots clustering and analysis

    Science.gov (United States)

    Yousef, Amr H.; Iftekharuddin, Khan; Karim, Mohammad

    2013-05-01

    A compact light detection and ranging (LiDAR) system is used for the purpose of aerosols profile measurements by identifying the aerosol scattering ratio as function of the altitude. These color plots can be treated as images with high intensities referring to high scattering ratios and low intensities referring to low scattering ratios. In this paper, we explore the clustering of these plots into homogeneous regions via unsupervised clustering techniques such as fuzzy techniques and evaluate their performance on this type of data. We introduce a new clustering technique to work efficiently on this type of images and compare its results against the regular techniques. By capturing different aerosols profiles at different times, we are able to describe the aerosol existence structure in the area of our interest.

  17. Soft seabed classification using Airborne LiDAR Bathymetry data

    Science.gov (United States)

    Narayanan, Ramasamy

    2011-12-01

    Coastal seabed mapping is essential for a variety of environmental management activities. Recently-introduced Airborne LiDAR Bathymetry (ALB) sensors allow, under favourable conditions, time and cost-efficient collection of shallow coastal seabed data in comparison to acoustics. One important application here, given seabed footprint size on the order to several meters in diameter for shallow waters, is the development of classification maps. The coastal seabed is typically a complex environment consisting of diversity and thus necessitates classification accounting for heterogeneity. Recent ALB classification studies have used techniques that assign each ALB shot to a single seabed class (i.e. hard classification) instead of assignment to multiple classes (i.e. soft classification). In this study, a Soft Seabed Classification (SSC) algorithm is developed with fuzzy clustering accounting for diversity. Both simulation and an ALB dataset of area approximately 20,000 m2 were used. Cross validation of the SSC approach yield favourable soft and hard classification accuracies.

  18. S-DARS broadcast from inclined, elliptical orbits

    Science.gov (United States)

    Briskman, Robert D.; Prevaux, Robert J.

    2004-04-01

    The first Sirius spacecraft was launched on July 1, 2000. Exactly 5 months later, on December 1, the third spacecraft was launched, completing the three satellite S-DARS (Satellite Digital Audio Radio Service) constellation. The three satellites are deployed in inclined, elliptical, geosynchronous orbits, which allow seamless broadcast coverage to mobile users in the contiguous US. Terrestrial broadcast repeaters provide service in urban cores. The system is in operation, providing the first ever S-DARS service. The constellation design results in satellite ground tracks over North America with two satellites always above the equator. High elevation look angles from the mobile ground terminals to the satellites minimize performance degradation due to blockage, foliage attenuation and multi-path. The spacecraft were built by Space Systems/Loral using the 1300 bus modified for operation in high inclination orbits. Each spacecraft was launched using a dedicated Russian Proton booster. The satellite payload is a bent pipe repeater using 7.1 GHz for the uplink and 2.3 GHz for the broadcast transmission. The repeater high-power amplification stage consists of 32 Traveling Wave Tube Amplifiers phase combined to yield a total radio frequency output power of nearly 4 kW at saturated operation. The satellite antennas are mechanically steered to maintain the transmit beam centered on the Contiguous United States and the receive beam centered on the uplink earth station located in Vernon Valley, New Jersey. The satellite payload design and performance are described. The principal spacecraft bus systems are described with emphasis on improvements made for operation in the inclined, elliptical geosynchronous orbits.

  19. Does participatory forest management promote sustainable forest utilisation in Tanzania?

    DEFF Research Database (Denmark)

    Treue, Thorsten; Ngaga, Y.M.

    2014-01-01

    Over the past 20 years, Participatory Forest Management (PFM) has become a dominant forest management strategy in Tanzania, covering more than 4.1 million hectares. Sustainable forest use and supply of wood products to local people are major aims of PFM. This paper assesses the sustainability of forest utilisation under PFM, using estimates of forest condition and extraction rates based on forest inventories and 480 household surveys from 12 forests; seven under Community Based Forest Management (CBFM), three under Joint Forest Management (JFM) and two under government management (non-PFM). Extraction of products is intense in forests close to Dar es Salaam, regardless of management regime. Further from Dar es Salaam, harvesting levels in forests under PFM are, with one prominent exception, broadly sustainable. Using GIS data from 116 wards, it is shown that half of the PFM forests in Tanzania are likely to be too small to satisfy current local wood demand.

  20. LiDAR Forest Inventory with Single-Tree, Double-, and Single-Phase Procedures

    Directory of Open Access Journals (Sweden)

    Robert C. Parker

    2009-01-01

    Full Text Available Light Detection and Ranging (LiDAR data at 0.5–2?m postings were used with double-sample, stratified procedures involving single-tree relationships in mixed, and single species stands to yield sampling errors ranging from ±2.1% to ±11.5%. LiDAR samples were selected with focal filter procedures and heights computed from interpolated canopy and DEM surfaces. Tree dbh and height data were obtained at various ratios of LiDAR, ground samples for DGPS located ground plots. Dbh-height and ground-LiDAR height models were used to predict dbh and compute Phase 2 estimates of basal area and volume. Phase 1 estimates were computed using the species probability distribution from ground plots in each strata. Phase 2 estimates were computed by randomly assigning LiDAR heights to species groups using a Monte Carlo simulation for each ground plot. There was no statistical difference between volume estimates from 0.5?m and 1?m LiDAR densities. Volume estimates from single-phase LiDAR procedures utilizing existing tree attributes and height bias relationships were obtained with sampling errors of 1.8% to 5.5%.

  1. LiDAR Forest Inventory with Single-Tree, Double-, and Single-Phase Procedures

    International Nuclear Information System (INIS)

    Light Detection and Ranging (LiDAR) data at 0.5-2 m postings were used with double-sample, stratified procedures involving single-tree relationships in mixed, and single species stands to yield sampling errors ranging from ±2.1% to ±11.5%. LiDAR samples were selected with focal filter procedures and heights computed from interpolated canopy and DEM surfaces. Tree dbh and height data were obtained at various ratios of LiDAR, ground samples for DGPS located ground plots. Dbh-height and ground-LiDAR height models were used to predict dbh and compute Phase 2 estimates of basal area and volume. Phase 1 estimates were computed using the species probability distribution from ground plots in each strata. Phase 2 estimates were computed by randomly assigning LiDAR heights to species groups using a Monte Carlo simulation for each ground plot. There was no statistical difference between volume estimates from 0.5 m and 1 m LiDAR densities. Volume estimates from single-phase LiDAR procedures utilizing existing tree attributes and height bias relationships were obtained with sampling errors of 1.8% to 5.5%.

  2. Hydrogeological Investigations of Deep Coastal Aquifers, Tanzania

    OpenAIRE

    James, Apolkarpi Peter

    2007-01-01

    ABSTRACT Borehole geophysical logging is viable method of determining the water quality and hydrogeological parameters of aquifers. A recent study was conducted to delineate the distribution of formation water salinity profile down to 600 meters below land surface of the Kimbiji coastal aquifer located 40 km south of the commercial capital, Dar es Salaam coastal plain in Tanzania. A hydrogeologic seismic cross section was also constructed. The borehole geophysical methods included short and l...

  3. Waste is a resource:A study on the opportunities in a new solid waste management in Iringa municipality

    OpenAIRE

    Solberg, Eirin

    2012-01-01

    Municipal solid waste refers to waste in a solid form, produced in the daily day life of a society such as packaging, food scrapes, grass clippings, clothing, furniture, paper, electronics and so on. It is called municipal solid waste because it is in the responsibility of the local government and comes from our homes, schools, hospitals and businesses. It is produced 108 tons municipal solid waste in Iringa each day. Iringa district is located approximately 500km from Dar Es Salaam and 263...

  4. TUKI 2004. Kamusi ya Kiswahili Sanifu. Toleo la Pili. [A standard Swahili dictionary. Second edition]. Nairobi: Oxford University Press. xviii, 477 pp. ISBN 0195732227. (ca. 15000 ThS/ 15.- €)

    OpenAIRE

    Herms, Irmtraud

    2012-01-01

    Book review: In 2004 the long awaited second edition of the Standard Swahili - Swahili Dictionary, edited by the Insitute of Kiswahili Research (TUKI) at the University of Dar es Salaam, appeared. With this publication TUKI has once again confirmed its leading role in the field of Swahili lexicography in East Africa. it is up to date, containing new words and phrases which are in use in East Africa in order to cope with the development in science and technology, society, economics and globali...

  5. Middle class construction: domestic architecture, aesthetics and anxieties in Tanzania

    OpenAIRE

    Mercer, Claire

    2014-01-01

    This paper examines the new styles of houses under construction in contemporary Tanzania and suggests that they can be understood as the material manifestation of middle class growth. Through an examination of the architecture, interior decor and compound space in a sample of these new houses in urban Dar es Salaam and rural Kilimanjaro, the paper identifies four domestic aesthetics: the respectable house, the locally aspirant house, the globally aspirant house and the minimalist house, each ...

  6. Prevention of intimate partner violence : community and healthcare workers´ perceptions in urban Tanzania

    OpenAIRE

    Laisser, Rose Mjawa

    2011-01-01

    Background: Intimate partner violence (IPV) against women is public health and human rights concern. The studies forming this thesis seek to understand healthcare worker and community attitudes and perceptions about IPV; their role in support, care and prevention of IPV, and the feasibility of introducing routine screening for IPV among women attending healthcare. Methods: Four interrelated studies were conducted in Temeke District, Dar es Salaam, Tanzania: 1) a content analysis of 16 in-dept...

  7. The Afya Bora Consortium: an African-U.S. partnership to Train Leaders in Global Health

    OpenAIRE

    Farquhar, Carey; Nathanson, Neal

    2011-01-01

    The Afya Bora Consortium is a partnership of eight academic health institutions, four in Africa and four in the United States. The Consortium members have a history of collaboration in four African-U.S. pairs: Makerere University, Kampala, Uganda, and Johns Hopkins University, Baltimore, Maryland, USA; Muhimbili University of Health and Allied Sciences, Dar es Salaam, Tanzania, and the University of California in San Francisco, California, USA; the University of Botswana, Gaborone, Botswana, ...

  8. Malaria in patients with sickle cell anemia: burden, risk factors, and outcome at the outpatient clinic and during hospitalization

    OpenAIRE

    Makani, J.; Komba, An; Cox, Se; Oruo, J.; Mwamtemi, K.; Kitundu, J.; Magesa, P.; Rwezaula, S.; Meda, E.; Mgaya, J.; Pallangyo, K.; Okiro, E.; Muturi, D.; Newton, CR; Fegan, G.

    2009-01-01

    Approximately 280,000 children are born with sickle cell anemia (SCA) in Africa annually, yet few survive beyond childhood. Falciparum malaria is considered a significant cause of this mortality. We conducted a 5-year prospective surveillance study for malaria parasitemia, clinical malaria, and severe malarial anemia (SMA) in Dar-es-Salaam, Tanzania, between 2004 and 2009. We recorded 10,491 visits to the outpatient clinic among 1808 patients with SCA and 773 visits among 679 patients without...

  9. Human bite injuries in the oro-facial region at the Muhimbili National Hospital, Tanzania

    OpenAIRE

    Nm, Simon Elison; Kalyanyama Boniphace M; Jm, Hamza Omar; Shubi Farrid M

    2008-01-01

    Abstract Background Human bites in the maxillofacial region compromise function and aesthetics, resulting in social and psychological effects. There is paucity of information regarding human bite injuries in Tanzania. The aim of the study was to assess the occurrence, treatment modalities and prognosis of human bite injuries in the oro-facial region at the Muhimbili National Hospital Dar es Salaam, Tanzania. Methods In a prospective study the details of patients with human bite injuries in th...

  10. Comparative analysis of public transport systems in African cities

    OpenAIRE

    Roux, Y. E.; Mfinanga, D.; Del Mistro, Romano F.

    2012-01-01

    This paper discusses the application of an assessment methodology on three African cities; Cape Town, Nairobi and Dar es Salaam. The purpose of the methodology is to do a comprehensive study on the performance of public transport systems in these cities. The methodology is used to describe, discuss and evaluate the public transport systems. A set of components and characteristics are needed to describe a public transport system of a city. The public transport goals and objectives of the citie...

  11. Challenges and approaches to the integration of HIS:case studies from Tanzania

    OpenAIRE

    Shidende, Nima H.

    2005-01-01

    This research falls under the area of design and implementation of information systems in developing countries. I have studied the health information systems in Tanzania using case studies in Ilala Municipal, situated in Dar es Salaam city, and Tabora Municipal in the Tabora region. The purpose of the research was to study the challenges encountered by the health workers at the local level with regard to information collection, use and reporting. The focus of this thesis is on problems of fra...

  12. Evaluation the Impact of a NGDO Social Entrepreneurship Course

    OpenAIRE

    Larsen, Tanja Lærke

    2013-01-01

    This is an evaluative study of students participating in the social entrepreneurship courses recently launched at the NDGO Action Aid Denmark’s training centre in Dar es Salaam, Tanzania. As proposed by the theory of planned behaviour, attitudes and intentions were used as predictors of future social entrepreneurial venture creation among the students. Data was collected through a survey distributed immediately after the courses and a follow-up survey distributed 2½-3 months later. The fol...

  13. Perceived University Students’ Attributions of Their Academic Success and Failure

    OpenAIRE

    Mkumbo, Kitila A. K.; Jacqueline Amani

    2012-01-01

    This study examined the applicability of the attribution theory in understanding how students attribute their academic success and failure. Participants involved a sample of 260 undergraduate students at the University of Dar es Salaam, Tanzania. They completed an attitude questionnaire scale with items on locus of control, stability and controllability dimensions. The results show that the majority of students attributed their academic performance to internal, stable and controllable factors...

  14. Psychological effects of business trainings in Tanzania

    OpenAIRE

    ?yniewska, Agnieszka Anna; Selezneva, Olga

    2009-01-01

    This master thesis, as a part of a project on business trainings in Tanzania, investigates the effects of these trainings on change in mindset and soft skills of microentrepreneurs in Dar es Salaam. It focuses on following dimensions: Creativity, Individualism, Locus of Control, Need for Achievement, Dispositional Optimism and Trust/Relationship. The significant differences are found on the number of dimensions. Entrepreneurs who took part in the training have more internal locus of control, ...

  15. LiDAR-derived snowpack data sets from mixed conifer forests across the Western United States

    Science.gov (United States)

    Harpold, A. A.; Guo, Q.; Molotch, N.; Brooks, P. D.; Bales, R.; Fernandez-Diaz, J. C.; Musselman, K. N.; Swetnam, T. L.; Kirchner, P.; Meadows, M. W.; Flanagan, J.; Lucas, R.

    2014-03-01

    Airborne-based Light Detection and Ranging (LiDAR) offers the potential to measure snow depth and vegetation structure at high spatial resolution over large extents and thereby increase our ability to quantify snow water resources. Here we present airborne LiDAR data products at four Critical Zone Observatories (CZO) in the Western United States: Jemez River Basin, NM, Boulder Creek Watershed, CO, Kings River Experimental Watershed, CA, and Wolverton Basin, CA. We make publicly available snow depth data products (1 m2 resolution) derived from LiDAR with an estimated accuracy of observations.

  16. Forest Roads Mapped Using LiDAR in Steep Forested Terrain

    OpenAIRE

    White, Russell A.; Dietterick, Brian C.; Thomas Mastin; Rollin Strohman

    2010-01-01

    LiDAR-derived digital elevation models can reveal road networks located beneath dense forest canopy. This study tests the accuracy of forest road characteristics mapped using LiDAR in the Santa Cruz Mountains, CA. The position, gradient, and total length of a forest haul road were accurately extracted using a 1 m DEM. In comparison to a field-surveyed centerline, the LiDAR-derived road exhibited a positional accuracy of 1.5 m, road grade measurements within 0.53% mean absolute difference, and...

  17. LiDAR Forest Inventory with Single-Tree, Double-, and Single-Phase Procedures

    OpenAIRE

    Parker, Robert C.; Evans, David L.

    2009-01-01

    Light Detection and Ranging (LiDAR) data at 0.5–2?m postings were used with double-sample, stratified procedures involving single-tree relationships in mixed, and single species stands to yield sampling errors ranging from ±2.1% to ±11.5%. LiDAR samples were selected with focal filter procedures and heights computed from interpolated canopy and DEM surfaces. Tree dbh and height data were obtained at various ratios of LiDAR, ground samples for DGPS located gr...

  18. ASTER GDEM validation using LiDAR data over coastal regions of Greenland

    OpenAIRE

    Hvidegaard, Sine Munk; Sørensen, Louise Sandberg; Forsberg, Rene?

    2011-01-01

    Elevation data from airborne Light Detection and Ranging (LiDAR) campaigns are used in an attempt to evaluate the accuracy of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) global digital elevation model (GDEM) in Greenland. The LiDAR elevation data set is characterized by a high spatial resolution of about 1 m and elevation accuracy of 20–30 cm root mean square error (RMSE). The LiDAR data sets used were acquired during ice-monitoring campaigns carried out f...

  19. Flood Modeling Using a Synthesis of Multi-Platform LiDAR Data

    OpenAIRE

    Csontos, Ryan M.; Colby, Jeffrey D.; Turner, Ashleigh B.; Michael Batten

    2013-01-01

    This study examined the utility of a high resolution ground-based (mobile and terrestrial) Light Detection and Ranging (LiDAR) dataset (0.2 m point-spacing) supplemented with a coarser resolution airborne LiDAR dataset (5 m point-spacing) for use in a flood inundation analysis. The techniques for combining multi-platform LiDAR data into a composite dataset in the form of a triangulated irregular network (TIN) are described, and quantitative comparisons were made to a TIN generated solely from...

  20. Compression strategies for LiDAR waveform cube

    Science.gov (United States)

    Jó?ków, Grzegorz; Toth, Charles; Quirk, Mihaela; Grejner-Brzezinska, Dorota

    2015-01-01

    Full-waveform LiDAR data (FWD) provide a wealth of information about the shape and materials of the surveyed areas. Unlike discrete data that retains only a few strong returns, FWD generally keeps the whole signal, at all times, regardless of the signal intensity. Hence, FWD will have an increasingly well-deserved role in mapping and beyond, in the much desired classification in the raw data format. Full-waveform systems currently perform only the recording of the waveform data at the acquisition stage; the return extraction is mostly deferred to post-processing. Although the full waveform preserves most of the details of the real data, it presents a serious practical challenge for a wide use: much larger datasets compared to those from the classical discrete return systems. Atop the need for more storage space, the acquisition speed of the FWD may also limit the pulse rate on most systems that cannot store data fast enough, and thus, reduces the perceived system performance. This work introduces a waveform cube model to compress waveforms in selected subsets of the cube, aimed at achieving decreased storage while maintaining the maximum pulse rate of FWD systems. In our experiments, the waveform cube is compressed using classical methods for 2D imagery that are further tested to assess the feasibility of the proposed solution. The spatial distribution of airborne waveform data is irregular; however, the manner of the FWD acquisition allows the organization of the waveforms in a regular 3D structure similar to familiar multi-component imagery, as those of hyper-spectral cubes or 3D volumetric tomography scans. This study presents the performance analysis of several lossy compression methods applied to the LiDAR waveform cube, including JPEG-1, JPEG-2000, and PCA-based techniques. Wide ranges of tests performed on real airborne datasets have demonstrated the benefits of the JPEG-2000 Standard where high compression rates incur fairly small data degradation. In addition, the JPEG-2000 Standard-compliant compression implementation can be fast and, thus, used in real-time systems, as compressed data sequences can be formed progressively during the waveform data collection. We conclude from our experiments that 2D image compression strategies are feasible and efficient approaches, thus they might be applied during the acquisition of the FWD sensors.

  1. Joint spatial Bayesian modeling for studies combining longitudinal and cross-sectional data.

    Science.gov (United States)

    Lawson, Andrew B; Carroll, Rachel; Castro, Marcia

    2014-12-01

    Design for intervention studies may combine longitudinal data collected from sampled locations over several survey rounds and cross-sectional data from other locations in the study area. In this case, modeling the impact of the intervention requires an approach that can accommodate both types of data, accounting for the dependence between individuals followed up over time. Inadequate modeling can mask intervention effects, with serious implications for policy making. In this paper we use data from a large-scale larviciding intervention for malaria control implemented in Dar es Salaam, United Republic of Tanzania, collected over a period of almost 5 years. We apply a longitudinal Bayesian spatial model to the Dar es Salaam data, combining follow-up and cross-sectional data, treating the correlation in longitudinal observations separately, and controlling for potential confounders. An innovative feature of this modeling is the use of Ornstein-Uhlenbeck process to model random time effects. We contrast the results with other Bayesian modeling formulations, including cross-sectional approaches that consider individual-level random effects to account for subjects followed up in two or more surveys. The longitudinal modeling approach indicates that the intervention significantly reduced the prevalence of malaria infection in Dar es Salaam by 20% whereas the joint model did not suggest significance within the results. Our results suggest that the longitudinal model is to be preferred when longitudinal information is available at the individual level. PMID:24713159

  2. Forest Roads Mapped Using LiDAR in Steep Forested Terrain

    Directory of Open Access Journals (Sweden)

    Russell A. White

    2010-04-01

    Full Text Available LiDAR-derived digital elevation models can reveal road networks located beneath dense forest canopy. This study tests the accuracy of forest road characteristics mapped using LiDAR in the Santa Cruz Mountains, CA. The position, gradient, and total length of a forest haul road were accurately extracted using a 1 m DEM. In comparison to a field-surveyed centerline, the LiDAR-derived road exhibited a positional accuracy of 1.5 m, road grade measurements within 0.53% mean absolute difference, and total road length within 0.2% of the field-surveyed length. Airborne LiDAR can provide thorough and accurate road inventory data to support forest management and watershed assessment activities.

  3. Detection of large above ground biomass variability in lowland forest ecosystems by airborne LiDAR

    OpenAIRE

    Jubanski, J.; Ballhorn, U.; Kronseder, K.; Franke, J.; Siegert, F.

    2012-01-01

    Quantification of tropical forest Above Ground Biomass (AGB) over large areas as input for Reduced Emissions from Deforestation and forest Degradation (REDD+) projects and climate change models is challenging. This is the first study which attempts to estimate AGB and its variability across large areas of tropical lowland forests in Central Kalimantan (Indonesia) through correlating airborne Light Detection and Ranging (LiDAR) to forest inventory data. Two LiDAR height metrics were ana...

  4. Improving Species Diversity and Biomass Estimates of Tropical Dry Forests Using Airborne LiDAR

    OpenAIRE

    José Luis Hernández-Stefanoni; Juan Manuel Dupuy; Johnson, Kristofer D.; Richard Birdsey; Fernando Tun-Dzul; Alicia Peduzzi; Juan Pablo Caamal-Sosa; Gonzalo Sánchez-Santos; David López-Merlín

    2014-01-01

    The spatial distribution of plant diversity and biomass informs management decisions to maintain biodiversity and carbon stocks in tropical forests. Optical remotely sensed data is often used for supporting such activities; however, it is difficult to estimate these variables in areas of high biomass. New technologies, such as airborne LiDAR, have been used to overcome such limitations. LiDAR has been increasingly used to map carbon stocks in tropical forests, but has rarely been used to esti...

  5. Characterisation of the surface morphology of an alpine alluvial fan using airborne LiDAR

    OpenAIRE

    Cavalli, M.; Marchi, L.

    2008-01-01

    Alluvial fans of alpine torrents are both natural deposition areas for sediment discharged by floods and debris flows, and preferred sites for agriculture and settlements. Hazard assessment on alluvial fans depends on proper identification of flow processes and their potential intensity. This study used LiDAR data to examine the morphology of the alluvial fan of a small alpine stream (Moscardo Torrent, Eastern Italian Alps). A high-resolution DTM from LiDAR data was used to calculate a shaded...

  6. Habitat Classification of Temperate Marine Macroalgal Communities Using Bathymetric LiDAR

    OpenAIRE

    Richard Zavalas; Daniel Ierodiaconou; David Ryan; Alex Rattray; Jacquomo Monk

    2014-01-01

    Here, we evaluated the potential of using bathymetric Light Detection and Ranging (LiDAR) to characterise shallow water (<30 m) benthic habitats of high energy subtidal coastal environments. Habitat classification, quantifying benthic substrata and macroalgal communities, was achieved in this study with the application of LiDAR and underwater video groundtruth data using automated classification techniques. Bathymetry and reflectance datasets were used to produce secondary terrain derivati...

  7. Engineering monitoring of rockfall hazards along transportation corridors: using mobile terrestrial LiDAR

    OpenAIRE

    Lato, M.; Hutchinson, J.; Diederichs, M.; Ball, D.; Harrap, R.

    2009-01-01

    Geotechnical hazards along linear transportation corridors are challenging to identify and often require constant monitoring. Inspecting corridors using traditional, manual methods requires the engineer to be unnecessarily exposed to the hazard. It also requires closure of the corridor to ensure safety of the worker from passing vehicles. This paper identifies the use of mobile terrestrial LiDAR data as a compliment to traditional field methods. Mobile terrestrial LiDAR is an emerging remote ...

  8. Airborne Dual-Wavelength LiDAR Data for Classifying Land Cover

    Directory of Open Access Journals (Sweden)

    Cheng-Kai Wang

    2014-01-01

    Full Text Available This study demonstrated the potential of using dual-wavelength airborne light detection and ranging (LiDAR data to classify land cover. Dual-wavelength LiDAR data were acquired from two airborne LiDAR systems that emitted pulses of light in near-infrared (NIR and middle-infrared (MIR lasers. The major features of the LiDAR data, such as surface height, echo width, and dual-wavelength amplitude, were used to represent the characteristics of land cover. Based on the major features of land cover, a support vector machine was used to classify six types of suburban land cover: road and gravel, bare soil, low vegetation, high vegetation, roofs, and water bodies. Results show that using dual-wavelength LiDAR-derived information (e.g., amplitudes at NIR and MIR wavelengths could compensate for the limitations of using single-wavelength LiDAR information (i.e., poor discrimination of low vegetation when classifying land cover.

  9. Area-Based Mapping of Defoliation of Scots Pine Stands Using Airborne Scanning LiDAR

    Directory of Open Access Journals (Sweden)

    Hannu Hyyppä

    2013-03-01

    Full Text Available The mapping of changes in the distribution of insect-caused forest damage remains an important forest monitoring application and challenge. Efficient and accurate methods are required for mapping and monitoring changes in insect defoliation to inform forest management and reporting activities. In this research, we develop and evaluate a LiDAR-driven (Light Detection And Ranging approach for mapping defoliation caused by the Common pine sawfly (Diprion pini L.. Our method requires plot-level training data and airborne scanning LiDAR data. The approach is predicated on a forest canopy mask created by detecting forest canopy cover using LiDAR. The LiDAR returns that are reflected from the canopy (that is, returns > half of maximum plot tree height are used in the prediction of the defoliation. Predictions of defoliation are made at plot-level, which enables a direct integration of the method to operational forest management planning while also providing additional value-added from inventory-focused LiDAR datasets. In addition to the method development, we evaluated the prediction accuracy and investigated the required pulse density for operational LiDAR-based mapping of defoliation. Our method proved to be suitable for the mapping of defoliated stands, resulting in an overall mapping accuracy of 84.3% and a Cohen’s kappa coefficient of 0.68.

  10. Adaptive Covariance Estimation Method for LiDAR-Aided Multi-Sensor Integrated Navigation Systems

    Directory of Open Access Journals (Sweden)

    Shifei Liu

    2015-01-01

    Full Text Available The accurate estimation of measurements covariance is a fundamental problem in sensors fusion algorithms and is crucial for the proper operation of filtering algorithms. This paper provides an innovative solution for this problem and realizes the proposed solution on a 2D indoor navigation system for unmanned ground vehicles (UGVs that fuses measurements from a MEMS-grade gyroscope, speed measurements and a light detection and ranging (LiDAR sensor. A computationally efficient weighted line extraction method is introduced, where the LiDAR intensity measurements are used, such that the random range errors and systematic errors due to surface reflectivity in LiDAR measurements are considered. The vehicle pose change is obtained from LiDAR line feature matching, and the corresponding pose change covariance is also estimated by a weighted least squares-based technique. The estimated LiDAR-based pose changes are applied as periodic updates to the Inertial Navigation System (INS in an innovative extended Kalman filter (EKF design. Besides, the influences of the environment geometry layout and line estimation error are discussed. Real experiments in indoor environment are performed to evaluate the proposed algorithm. The results showed the great consistency between the LiDAR-estimated pose change covariance and the true accuracy. Therefore, this leads to a significant improvement in the vehicle’s integrated navigation accuracy.

  11. A Cyberinfrastructure Platform for Distribution of GeoEarthScope LiDAR Topography Data

    Science.gov (United States)

    Crosby, C. J.; Nandigam, V.; Arrowsmith, J. R.; Balakrishnan, S.; Alex, N.; Baru, C.

    2008-12-01

    The recently completed GeoEarthScope airborne LiDAR (Light Detection And Ranging) topography acquisition will provide unprecedented data adjacent to active faults throughout the plate boundary region of western North America. Totaling more than 5000 square kilometers, these community-oriented data offer an high-resolution representation of fault zone topography and should be a revolutionary resource for researchers studying earthquake hazards, active faulting, landscape processes, and ground deformation. Since spring of 2007, the NSF-funded GeoEarthScope LiDAR project has acquired data for the San Andreas fault system in northern California, faults in southern California, the Yakima Fold and Thrust Belt in Washington, Yellowstone National Park, the Tetons, the Wasatch Front, and Alaska. These data will be made available via the OpenTopography Portal (www.opentopography.org), a domain-specific component of the GEON project, as they are processed and delivered by the National Center for Airborne Laser Mapping. The OpenTopography Portal (OpenToPo) provides access to a variety of GeoEarthScope LiDAR data products and uses several cyberinfrastructure components developed by the GEON project. These products range from simple Google Earth visualizations of LiDAR hillshades to standard digital elevation model (DEM) products as well as LiDAR point cloud data. The wide spectrum of LiDAR users have variable scientific applications, computing resources and technical experience and thus require a data distribution system that provides various levels of access to the data. Standard DEM products in OpenToPo are accessed via a Google Map and/or Google Earth-based interface that allow users to browse and download the data products. For users who wish to explore the full potential of the LiDAR data, we provide access to the raw LiDAR point data and a suite of DEM generation tools to enable users to create custom DEMs to best fit their science applications. Storage and management of these multi-billion point LiDAR datasets is done via a partitioned spatial database that is deployed across a multi node cluster. The innovative database architecture allows for high performance as well as high scalability. Once a subset of data is defined in the Google Map interface, users are able to define their processing parameters and submit jobs to run on OpenToPo computing resources. By using cyberinfrastructure-based resources to provide access to the large volumes of GeoEarthScope LiDAR topography, OpenToPo democratizes access to these exciting but often challenging datasets.

  12. Independent evaluation of the SNODAS snow depth product using regional scale LiDAR-derived measurements

    Directory of Open Access Journals (Sweden)

    A. Hedrick

    2014-06-01

    Full Text Available Repeated Light Detection and Ranging (LiDAR surveys are quickly becoming the de facto method for measuring spatial variability of montane snowpacks at high resolution. This study examines the potential of a 750 km2 LiDAR-derived dataset of snow depths, collected during the 2007 northern Colorado Cold Lands Processes Experiment (CLPX-2, as a validation source for an operational hydrologic snow model. The SNOw Data Assimilation System (SNODAS model framework, operated by the US National Weather Service, combines a physically-based energy-and-mass-balance snow model with satellite, airborne and automated ground-based observations to provide daily estimates of snowpack properties at nominally 1 km resolution over the coterminous United States. Independent validation data is scarce due to the assimilating nature of SNODAS, compelling the need for an independent validation dataset with substantial geographic coverage. Within twelve distinctive 500 m × 500 m study areas located throughout the survey swath, ground crews performed approximately 600 manual snow depth measurements during each of the CLPX-2 LiDAR acquisitions. This supplied a dataset for constraining the uncertainty of upscaled LiDAR estimates of snow depth at the 1 km SNODAS resolution, resulting in a root-mean-square difference of 13 cm. Upscaled LiDAR snow depths were then compared to the SNODAS-estimates over the entire study area for the dates of the LiDAR flights. The remotely-sensed snow depths provided a more spatially continuous comparison dataset and agreed more closely to the model estimates than that of the in situ measurements alone. Finally, the results revealed three distinct areas where the differences between LiDAR observations and SNODAS estimates were most drastic, suggesting natural processes specific to these regions as causal influences on model uncertainty.

  13. LiDAR Applications in Resource Geology and Benefits for Land Management

    Science.gov (United States)

    Mikulovsky, R. P.; De La Fuente, J. A.

    2013-12-01

    The US Forest Service (US Department of Agriculture) manages a broad range of geologic resources and hazards on National Forests and Grass Lands throughout the United States. Resources include rock and earth materials, groundwater, caves and paleontological resources, minerals, energy resources, and unique geologic areas. Hazards include landslides, floods, earthquakes, volcanic eruptions, and naturally hazardous materials (e.g., asbestos, radon). Forest Service Geologists who address these issues are Resource Geologists. They have been exploring LiDAR as a revolutionary tool to efficiently manage all of these hazards and resources. However, most LiDAR applications for management have focused on timber and fuels management, rather than landforms. This study shows the applications and preliminary results of using LiDAR for managing geologic resources and hazards on public lands. Applications shown include calculating sediment budgets, mapping and monitoring landslides, mapping and characterizing borrow pits or mines, determining landslide potential, mapping faults, and characterizing groundwater dependent ecosystems. LiDAR can be used to model potential locations of groundwater dependent ecosystems with threatened or endangered plant species such as Howellia aquatilis. This difficult to locate species typically exists on the Mendocino National Forest within sag ponds on landslide benches. LiDAR metrics of known sites are used to model potential habitat. Thus LiDAR can link the disciplines of geology, hydrology, botany, archaeology and others for enhanced land management. As LiDAR acquisition costs decrease and it becomes more accessible, land management organizations will find a wealth of applications with potential far-reaching benefits for managing geologic resources and hazards.

  14. Independent evaluation of the SNODAS snow depth product using regional scale LiDAR-derived measurements

    Science.gov (United States)

    Hedrick, A.; Marshall, H.-P.; Winstral, A.; Elder, K.; Yueh, S.; Cline, D.

    2014-06-01

    Repeated Light Detection and Ranging (LiDAR) surveys are quickly becoming the de facto method for measuring spatial variability of montane snowpacks at high resolution. This study examines the potential of a 750 km2 LiDAR-derived dataset of snow depths, collected during the 2007 northern Colorado Cold Lands Processes Experiment (CLPX-2), as a validation source for an operational hydrologic snow model. The SNOw Data Assimilation System (SNODAS) model framework, operated by the US National Weather Service, combines a physically-based energy-and-mass-balance snow model with satellite, airborne and automated ground-based observations to provide daily estimates of snowpack properties at nominally 1 km resolution over the coterminous United States. Independent validation data is scarce due to the assimilating nature of SNODAS, compelling the need for an independent validation dataset with substantial geographic coverage. Within twelve distinctive 500 m × 500 m study areas located throughout the survey swath, ground crews performed approximately 600 manual snow depth measurements during each of the CLPX-2 LiDAR acquisitions. This supplied a dataset for constraining the uncertainty of upscaled LiDAR estimates of snow depth at the 1 km SNODAS resolution, resulting in a root-mean-square difference of 13 cm. Upscaled LiDAR snow depths were then compared to the SNODAS-estimates over the entire study area for the dates of the LiDAR flights. The remotely-sensed snow depths provided a more spatially continuous comparison dataset and agreed more closely to the model estimates than that of the in situ measurements alone. Finally, the results revealed three distinct areas where the differences between LiDAR observations and SNODAS estimates were most drastic, suggesting natural processes specific to these regions as causal influences on model uncertainty.

  15. Estimation of effective plant area index for South Korean forests using LiDAR system.

    Science.gov (United States)

    Kwak, Doo-Ahn; Lee, Woo-Kyun; Kafatos, Menas; Son, Yowhan; Cho, Hyun-Kook; Lee, Seung-Ho

    2010-07-01

    Light Detection and Ranging (LiDAR) systems can be used to estimate both vertical and horizontal forest structure. Woody components, the leaves of trees and the understory can be described with high precision, using geo-registered 3D-points. Based on this concept, the Effective Plant Area Indices (PAI(e)) for areas of Korean Pine (Pinus koraiensis), Japanese Larch (Larix leptolepis) and Oak (Quercus spp.) were estimated by calculating the ratio of intercepted and incident LIDAR laser rays for the canopies of the three forest types. Initially, the canopy gap fraction (G ( LiDAR )) was generated by extracting the LiDAR data reflected from the canopy surface, or inner canopy area, using k-means statistics. The LiDAR-derived PAI(e) was then estimated by using G ( LIDAR ) with the Beer-Lambert law. A comparison of the LiDAR-derived and field-derived PAI(e) revealed the coefficients of determination for Korean Pine, Japanese Larch and Oak to be 0.82, 0.64 and 0.59, respectively. These differences between field-based and LIDAR-based PAI(e) for the different forest types were attributed to the amount of leaves and branches in the forest stands. The absence of leaves, in the case of both Larch and Oak, meant that the LiDAR pulses were only reflected from branches. The probability that the LiDAR pulses are reflected from bare branches is low as compared to the reflection from branches with a high leaf density. This is because the size of the branch is smaller than the resolution across and along the 1 meter LIDAR laser track. Therefore, a better predictive accuracy would be expected for the model if the study would be repeated in late spring when the shoots and leaves of the deciduous trees begin to appear. PMID:20697878

  16. Estimating snow volume in mountain catchments using Aerial LiDAR

    Science.gov (United States)

    Shallcross, A. T.; McNamara, J. P.; Marshall, H.; Marks, D. G.; Link, T. E.; Winstral, A. H.

    2009-12-01

    Numerous hydrologic problems would benefit from knowing the true volume of snow in a mountainous catchment. Unfortunately, field based techniques commonly fall short due to their inability to adequately capture the spatial variability of snow in complex terrain. LiDAR has been used to map snow cover by differencing digital elevation models of snow free and snow covered ground. Although this technique has shown promise, the accuracy of the method depends on the reliability and accuracy of the snow-free LiDAR-derived ground elevations used to generate the DEM. Uncertainties have been detected in shrub-dominated areas where LiDAR-processing algorithms seem unable to separate shrub canopy from ground. Misclassification of ground elevation can lead to errors in LiDAR-derived snow depth, including negative depth estimates in locations where shrubs are matted down and completely buried during snow deposition. LiDAR-derived snow depth estimates are also subject to other errors including overestimates in areas with dense shrubs, missing data around tree bowls, and misclassification of terrain features by processing algorithms. Inaccuracies in the x, y, and z directions can translate into significant errors in snow volume estimates, especially on steep slopes. To assess the reliability of LiDAR derived snow estimates, associated errors need to be quantified. This study attempts to identify and quantify the errors associated with LiDAR derived snow volume estimates for the mountainous terrain of the Dry Creek Experimental Watershed, ID. Preliminary results indicate that the errors can be on the order of magnitude equal to the snow depth.

  17. ¿Qué es la justicia global?

    Directory of Open Access Journals (Sweden)

    Thomas Pogge

    2007-11-01

    Full Text Available Ya existen más libros y ensayos sobre "justicia global" en este milenio que en el anterior, al menos según lo que indican las computadoras. Algunos de los temas más amplios que se discuten hoy bajo el título "justicia global" se vienen tratando desde hace siglos, inclusive desde el principio de la civilización, pero se los discutía bajo distintos rótulos, tales como "justicia internacional", "ética internacional" y "la ley de las naciones". Este ensayo explora el significado de tal desplazamiento en la terminología. Un rasgo distintivo del marco filosófico asociado con la expresión "justicia global" es el hecho de destacar el análisis causal y moral del orden institucional global contra el trasfondo de sus alternativas viables y alcanzables. Dentro de este enfoque general de la justicia global, las diferentes concepciones de la justicia global diferirán en los criterios específicos de justicia global que proponen. No obstante ello, esos criterios coincidirán en enfatizar la cuestión sobre cómo funciona nuestro orden institucional global en comparación con sus alternativas viables y alcanzables, en lo que respecta a los intereses humanos fundamentales que resultan relevantes desde un punto de vista moral. Al extender el análisis institucional moral más allá del estado, esta pregunta centra la atención sobre de qué manera la incidencia masiva actual de la violencia y la pobreza extrema, y los profundos excesos de mortalidad y morbilidad que provocan, se pueden evitar -no sencillamente a través de una mejor conducta por parte de los gobiernos, en el plano interno y el internacional sino también, y de manera mucho más efectiva, a través de reformas institucionales globales que, entre otras cosas, mejorarían esa conducta gubernamental al modificar las opciones a disposición de los gobiernos y los incentivos que enfrentan.There are more books and essays on 'global justice' in this millennium already than in the preceding one, at least as far as computers can tell. Some of the broad topics currently debated under the heading of "global justice" have been discussed for centuries, back to the beginnings of civilization. But they were discussed under different labels, such as "international justice", "international ethics," and "the law of nations." This essay explores the significance of this shift in terminology. Distinctive of the philosophical framework associated with the increasingly prominent expression "global justice." is the focus on the causal and moral analysis of the global institutional order against the background of its feasible and reachable alternatives. Within this general global-justice approach, distinct conceptions of global justice will differ in the specific criteria of global justice they propose. But such criteria will coincide in their emphasis on the question of how well our global institutional order is doing, compared to its feasible and reachable alternatives, in regard to the fundamental human interests that matter from a moral point of view. Extending institutional moral analysis beyond the state, this question focuses attention on how today's massive incidence of violence and severe poverty, and the huge excesses of mortality and morbidity they cause might be avoided not merely through better government behavior, internally and internationally, but also, and much more effectively, through global institutional reforms that would, among other things, elevate such government behavior by modifying the options governments have and the incentives they face.

  18. ¿Qué es la justicia global?

    Scientific Electronic Library Online (English)

    Thomas, Pogge.

    2007-11-01

    Full Text Available Ya existen más libros y ensayos sobre "justicia global" en este milenio que en el anterior, al menos según lo que indican las computadoras. Algunos de los temas más amplios que se discuten hoy bajo el título "justicia global" se vienen tratando desde hace siglos, inclusive desde el principio de la c [...] ivilización, pero se los discutía bajo distintos rótulos, tales como "justicia internacional", "ética internacional" y "la ley de las naciones". Este ensayo explora el significado de tal desplazamiento en la terminología. Un rasgo distintivo del marco filosófico asociado con la expresión "justicia global" es el hecho de destacar el análisis causal y moral del orden institucional global contra el trasfondo de sus alternativas viables y alcanzables. Dentro de este enfoque general de la justicia global, las diferentes concepciones de la justicia global diferirán en los criterios específicos de justicia global que proponen. No obstante ello, esos criterios coincidirán en enfatizar la cuestión sobre cómo funciona nuestro orden institucional global en comparación con sus alternativas viables y alcanzables, en lo que respecta a los intereses humanos fundamentales que resultan relevantes desde un punto de vista moral. Al extender el análisis institucional moral más allá del estado, esta pregunta centra la atención sobre de qué manera la incidencia masiva actual de la violencia y la pobreza extrema, y los profundos excesos de mortalidad y morbilidad que provocan, se pueden evitar -no sencillamente a través de una mejor conducta por parte de los gobiernos, en el plano interno y el internacional sino también, y de manera mucho más efectiva, a través de reformas institucionales globales que, entre otras cosas, mejorarían esa conducta gubernamental al modificar las opciones a disposición de los gobiernos y los incentivos que enfrentan. Abstract in english There are more books and essays on 'global justice' in this millennium already than in the preceding one, at least as far as computers can tell. Some of the broad topics currently debated under the heading of "global justice" have been discussed for centuries, back to the beginnings of civilization. [...] But they were discussed under different labels, such as "international justice", "international ethics," and "the law of nations." This essay explores the significance of this shift in terminology. Distinctive of the philosophical framework associated with the increasingly prominent expression "global justice." is the focus on the causal and moral analysis of the global institutional order against the background of its feasible and reachable alternatives. Within this general global-justice approach, distinct conceptions of global justice will differ in the specific criteria of global justice they propose. But such criteria will coincide in their emphasis on the question of how well our global institutional order is doing, compared to its feasible and reachable alternatives, in regard to the fundamental human interests that matter from a moral point of view. Extending institutional moral analysis beyond the state, this question focuses attention on how today's massive incidence of violence and severe poverty, and the huge excesses of mortality and morbidity they cause might be avoided not merely through better government behavior, internally and internationally, but also, and much more effectively, through global institutional reforms that would, among other things, elevate such government behavior by modifying the options governments have and the incentives they face.

  19. LDL-Cholesterin: Wie stark soll es gesenkt werden?

    Directory of Open Access Journals (Sweden)

    Paulweber B

    2002-01-01

    Full Text Available Der klinische Nutzen einer LDL-C-Senkung mittels Statinen wurde in zahlreichen Studien zweifelsfrei nachgewiesen. Die im letzten Jahr veröffentlichten ATP III-Richtlinien stellen eine gute und praxisnahe Hilfestellung für die Entscheidung dar, ob eine Statintherapie eingeleitet und welche Zielwerte angestrebt werden sollen. Die wichtige Frage, ob eine noch aggressivere LDL-C-Senkung zu niedrigeren Zielwerten, als sie in diesen Richtlinien empfohlen werden (unter 80 mg/dl, einen zusätzlichen Nutzen bringt, ist noch nicht beantwortet. Wenn ein solcher Zusatznutzen erzielbar ist, so muß er jedenfalls gegen das möglicherweise erhöhte Nebenwirkungsrisiko einer dazu erforderlichen hochdosierten Statintherapie abgewogen werden. Es ist zu erwarten, daß die Ergebnisse laufender randomisierter Doppelblindstudien zur Klärung dieser Frage in den nächsten Jahren wesentlich beitragen werden. Die kürzlich veröffentlichten Ergebnisse der Heart Protection Study legen den Schluß nahe, daß bei Hochrisikopatienten eine LDL-Senkung im Ausmaß von 30-40 % in jedem Fall erfolgen sollte, auch wenn ein niedriger Ausgangswert des LDL-C vorliegt. Aufgrund von Daten der SAPHIR-Studie (Salzburger Atherosklerose-Präventionsprogramm bei Personen mit hohem Infarkt-Risiko kann abgeschätzt werden, daß gemäß ATP III etwa 20 % der Männer zwischen 40 und 55 Jahren und etwa 8 % der Frauen zwischen 50 und 65 Jahren mit einem Statin behandelt werden sollten. Ein neues hochpotentes Statin (Rosuvastatin, mit dem die empfohlenen Zielwerte noch besser als mit bisher verfügbaren Statinen erreicht werden können, steht kurz vor der Markteinführung. Ezetimibe ist ein Vertreter einer neuen Medikamentenklasse, der selektiven Cholesterinresorptionshemmer. Die Kombination einer niedrigen Statindosis mit Ezetimibe führt zu einer sehr effektiven LDL-C-Senkung, die in derselben Größenordnung liegt, wie sie durch Maximaldosen hochpotenter Statine erzielt werden kann.

  20. LiDAR: principles and forestry applications LiDAR: princípios e aplicações florestais

    Directory of Open Access Journals (Sweden)

    Marcos Giongo

    2010-12-01

    Full Text Available One of the first areas investigated for commercial applications of LiDAR was for forest applications. Topography and forest coverage are of extreme importance for forest resources managers. Accurate information on trees height and density, besides being fundamental for planning, are hard to obtain by conventional methods. Laser scanning technology, as opposed to satellite images and aerial photographs, can concurrently map the ground and obtain estimates of trees height. The use of modeling associated with LiDAR data allows to obtain estimates of several other forest variables such as basal area, diameter, volume,�  biomass and fuel material. Besides these applications, LiDAR technology presents a great potential for planning forest harvesting activities, road construction and maintenance. However, there are great challenges to be overcome in developing technologies and computational applications more robust and reliable for modeling data from this type of sensor.

    doi: 10.4336/2010.pfb.30.63.231

  1. Geometric Calibration and Radiometric Correction of LiDAR Data and Their Impact on the Quality of Derived Products

    OpenAIRE

    Wai-Yeung Yan; Ahmed Shaker; Habib, Ayman F.; Kersting, Ana P.

    2011-01-01

    LiDAR (Light Detection And Ranging) systems are capable of providing 3D positional and spectral information (in the utilized spectrum range) of the mapped surface. Due to systematic errors in the system parameters and measurements, LiDAR systems require geometric calibration and radiometric correction of the intensity data in order to maximize the benefit from the collected positional and spectral information. This paper presents a practical approach for the geometric calibration of LiDAR sys...

  2. Nos fios de Ariádne: cartografia da relação saúdetrabalho numa escola pública de Vitória-ES

    Directory of Open Access Journals (Sweden)

    Marinete Rosa Pereira Mascarello

    2007-01-01

    Full Text Available En los hilos de Ariadna: cartografía de la relación salud-trabajo en una escuela pública de Vitória-ES Se trata del estudio cualitativo abordando las relaciones entre salud y trabajo de los profesores de una escuela pública en la ciudad de Vitória, capital del estado de Espíritu Santo. Su objetivo fue cartografiar las vivencias de placer y sufrimiento de los docentes, principalmente las estrategias creadas para defenderse de las nocividades del ambiente de trabajo y producir salud. Afirma la insociabilidad entre modos de trabajar y modos de subjetivar, y constata que la deteriorización del sistema público de enseñanza ha producido sus efectos en el trabajo del profesorado, comprometiendo la salud de esos profesionales y causando, muchas veces, su alejamiento de las funciones por medio de licencias médicas o mismo abandono de la profesión. Busca dar visibilidades a las acciones que apuntan para la recreación del trabajo, mismo dentro de condiciones adversas.

  3. Kai kuriose daržov?se aptikti nematod? pernešami virusini? lig? suk?l?jai

    OpenAIRE

    Zitikaite?, Irena

    2008-01-01

    Vizualiai tyrin?jant ?vairi? daržovi? virusini? lig? pob?d? buvo pasteb?ta agurk?, pomidor? ir cukinij?, kuri? lapuose ar vaisiuose buvo žiediškoji d?m?tlig?, chlorotinis margumas ir ?vairios lap? ir augal? virš?ni? deformacijos. Užsikr?tusi? daržovi? pavyzdžiai tyrimams buvo paimti priva?iuose daržuose, lauke ir šiltnamiuose Vilniaus, Kauno, K?daini? rajonuose. Tiriant min?t? daržovi? lap? ekstraktus, peršvie?iamosios elektronin?s mikroskopijos met...

  4. Analysis of full-waveform LiDAR data for forestry applications: a review of investigations and methods

    OpenAIRE

    Pirotti F

    2011-01-01

    The goal of this review is to present leading examples of current methodologies for extracting forest characteristics from full-waveform LiDAR data. Four key questions are addressed: (i) does full-waveform LiDAR provide advantages over discrete-return laser sensors; (ii) will full-waveform LiDAR provide valid results in support of forest inventory operations and allow for a decrease in ground sampling efforts; (iii) is the use of full-waveform LiDAR data cost effective; and (iv) what is the s...

  5. Comprehensive Utilization of Temporal and Spatial Domain Outlier Detection Methods for Mobile Terrestrial LiDAR Data

    OpenAIRE

    Baoxin Hu; Jian-guo Wang; Michael Leslar

    2011-01-01

    Terrestrial LiDAR provides many disciplines with an effective and efficient means of producing realistic three-dimensional models of real world objects. With the advent of mobile terrestrial LiDAR, this ability has been expanded to include the rapid collection of three-dimensional models of large urban scenes. For all its usefulness, it does have drawbacks. One of the major problems faced by the LiDAR industry today is the automatic removal of outlying data points from LiDAR point clouds. Thi...

  6. Geotechnical applications of LiDAR pertaining to geomechanical evaluation and hazard identification

    Science.gov (United States)

    Lato, Matthew J.

    Natural hazards related to ground movement that directly affect the safety of motorists and highway infrastructure include, but are not limited to, rockfalls, rockslides, debris flows, and landslides. This thesis specifically deals with the evaluation of rockfall hazards through the evaluation of LiDAR data. Light Detection And Ranging (LiDAR) is an imaging technology that can be used to delineate and evaluate geomechanically-controlled hazards. LiDAR has been adopted to conduct hazard evaluations pertaining to rockfall, rock-avalanches, debris flows, and landslides. Characteristics of LiDAR surveying, such as rapid data acquisition rates, mobile data collection, and high data densities, pose problems to traditional CAD or GIS-based mapping methods. New analyses methods, including tools specifically oriented to geomechanical analyses, are needed. The research completed in this thesis supports development of new methods, including improved survey techniques, innovative software workflows, and processing algorithms to aid in the detection and evaluation of geomechanically controlled rockfall hazards. The scientific research conducted between the years of 2006-2010, as presented in this thesis, are divided into five chapters, each of which has been published by or is under review by an international journal. The five research foci are: (i) geomechanical feature extraction and analysis using LiDAR data in active mining environments; (ii) engineered monitoring of rockfall hazards along transportation corridors: using mobile terrestrial LiDAR; (iii) optimization of LiDAR scanning and processing for automated structural evaluation of discontinuities in rockmasses; (iv) location orientation bias when using static LiDAR data for geomechanical analysis; and (v) evaluating roadside rockmasses for rockfall hazards from LiDAR data: optimizing data collection and processing protocols. The research conducted pertaining to this thesis has direct and significant implications with respect to numerous engineering projects that are affected by geomechanical stability issues. The ability to efficiently and accurately map discontinuities, detect changes, and standardize roadside geomechanical stability analyses from remote locations will fundamentally change the state-of-practice of geotechnical investigation workflows and repeatable monitoring. This, in turn, will lead to earlier detection and definition of potential zones of instability, will allow for progressive monitoring and risk analysis, and will indicate the need for pro-active slope improvement and stabilization.

  7. Maternal delays in utilizing institutional delivery services, Bahir Dar, Ethiopia

    Directory of Open Access Journals (Sweden)

    Worku Awoke

    2013-06-01

    Full Text Available Introduction: Timely referrals and access to appropriate health care had a great impact on reduction to maternal deaths and disabilities. Maternal delay is one of the contributing factors for high maternal mortality in developing countries. Maternal delays were categorized into three levels: delay in making the decision for seeking care, delay in arrival at a health facility, and delay in receiving adequate treatment. They have been named first, second, and third delay maternal delays; respectively. This study was aimed at assessing maternal delays in utilizing institutional delivery service sin Bahir Dar, North-Western Ethiopia. Methods: A cross sectional facility based study was conducted on a sample of 422 women attending at a public health facility for delivery services. The sample size was determined by using single population proportion formula and the study participants were selected by using a systematic random sampling method. Data were collected by means of a pre-tested, standardized questionnaire; analysis was carried out using SPSS version 16. Results: Data was collected from 410 laboring mothers. First delay, 155 (37.8% of mothers was delayed in decision making for seeking care from the public health facility and the mean delay was 8 hours. Delay in seeking emergency obstetric care [EOC] was about seven fold among illiterate mothers (AOR, 6.71; 95%CI, 3.66 -12.29 than literate mothers; the odds of delay for EOC were three times more likely among mother were unable to make decisions by their own (AOR, 3.30; 95%CI, 1.25 -7.20 than those mothers who made the decisions of their own. Unemployed mothers were 4 times more likely to have the maternal delay in seeking EOC (AOR, 3.94; 95%CI, 2.36 -6.57 than employed mothers. Second delay, 130 (31.7% of mothers had transportation problems in reaching health care facilities. Predictors in the first maternal delay were also the major contributing factors for this delay. The third delay, after their arrival at health facilities, 126 (30.7% mothers reported that they did not get the services on time; the mean waiting time for getting the service was 4 hours. Conclusions: Many mothers were not getting institutional delivery care services in a timely manner, due to the “three maternal delays”. Mothers’ literacy, decision making power and employment status were the main predictors for delivery service utilization. Hence, emphasis should be given for awareness creation on the risks of maternal delays, designing income generating mechanism, women empowering for in decision making and ambulance services should be strengthened.

  8. Agrotóxico: que nome dar? Pesticide: how can it named?

    Directory of Open Access Journals (Sweden)

    Márcia Gomide

    2005-12-01

    Full Text Available Os trabalhadores, de um modo geral, estão sempre expostos a maiores ou menores intensidades de risco. Os agricultores, em particular, também estão expostos e de forma bastante estabelecida. Contudo, trabalhos têm mostrado que existe um código coletivo de proteção para lhes permitir dar continuidade às suas atividades, uma vez que, em sua maioria, os próprios donos do cultivo fazem parte do processo produtivo e, portanto, precisam garantir a sua safra aplicando os agrotóxicos. Este trabalho apresenta uma pesquisa desenvolvida com agricultores de dois municípios do sudeste do Piauí, utilizando uma abordagem qualitativa, com o intuito de compreender os mecanismos de proteção destes agricultores com a sua atividade. Os resultados apontaram para práticas defensivas tais como consumo de bebida alcoólica, a sublocação do serviço aos mais jovens e a existência de um certo grau de compreensão do risco à saúde com a utilização dos agrotóxicos. A partir daí, se discute a importância da denominação dada ao agrotóxico, como um fator de proteção que deveria ser mais valorizado para maximizar a proteção do agricultor, em vez de se manter a estratégia de aumento de informação e controle de EPI (Equipamento de Proteção Individual.Workers, generally speaking, are always exposed to higher or lower risk degrees. Farmers are particularly exposed, which is demonstrated in the specialized literature. Nevertheless, papers have stated that there are, in fact, some sort of common protection law that permit them carry on their activities. This is because the majority of the employers take part in the production process to guarantee their harvests using pesticide. This paper presents a research carried out in two cities in the Southwest Piauí State using a qualitative approach in order to understand the protection mechanisms farmers perform against their occupational hazards. The outcomes reveal defensive strategies such as alcohol consumption and subletting work to younger workers. There is also the existence of some level of awareness about the risks of pesticide use to health. Considering that, the importance of the designation given to pesticides as a protection factor must be discussed and that should be more valorized in order to maximize farmers self-protection instead of insisting on the information increase or the personal protection equipaments control strategies.

  9. Evolutionary feature selection to estimate forest stand variables using LiDAR

    Science.gov (United States)

    Garcia-Gutierrez, Jorge; Gonzalez-Ferreiro, Eduardo; Riquelme-Santos, Jose C.; Miranda, David; Dieguez-Aranda, Ulises; Navarro-Cerrillo, Rafael M.

    2014-02-01

    Light detection and ranging (LiDAR) has become an important tool in forestry. LiDAR-derived models are mostly developed by means of multiple linear regression (MLR) after stepwise selection of predictors. An increasing interest in machine learning and evolutionary computation has recently arisen to improve regression use in LiDAR data processing. Although evolutionary machine learning has already proven to be suitable for regression, evolutionary computation may also be applied to improve parametric models such as MLR. This paper provides a hybrid approach based on joint use of MLR and a novel genetic algorithm for the estimation of the main forest stand variables. We show a comparison between our genetic approach and other common methods of selecting predictors. The results obtained from several LiDAR datasets with different pulse densities in two areas of the Iberian Peninsula indicate that genetic algorithms perform better than the other methods statistically. Preliminary studies suggest that a lack of parametric conditions in field data and possible misuse of parametric tests may be the main reasons for the better performance of the genetic algorithm. This research confirms the findings of previous studies that outline the importance of evolutionary computation in the context of LiDAR analisys of forest data, especially when the size of fieldwork datatasets is reduced.

  10. Specular and diffuse object extraction from a LiDAR derived Digital Surface Model (DSM)

    Science.gov (United States)

    Saraf, N. M.; Hamid, J. R. A.; Kamaruddin, M. H.

    2014-02-01

    This paper intents to investigate the indifferent behaviour quantitatively of target objects of interest due to specular and diffuse reflectivity based on generated LiDAR DSM of the study site in Ampang, Kuala Lumpur. The LiDAR data to be used was initially checked for its reliability and accuracy. The point cloud LiDAR data was converted to raster to allow grid analysis of the next process of generating the DSM and DTM. Filtering and masking were made removing the features of interest (i.e. building and tree) and other unwanted above surface features. A normalised DSM and object segmentation approach were conducted on the trees and buildings separately. Error assessment and findings attained were highlighted and documented. The result of LiDAR verification certified that the data is reliable and useable. The RMSE obtained is within the tolerance value of horizontal and vertical accuracy (x, y, z) i.e. 0.159 m, 0.211 m 0.091 m respectively. Building extraction inclusive of roof top based on slope and contour analysis undertaken indicate the capability of the approach while single tree extraction through aspect analysis appears to preserve the accuracy of the extraction accordingly. The paper has evaluated the suitable methods of extracting non-ground features and the effective segmentation of the LiDAR data.

  11. Development of LiDAR measurements for the German offshore test site

    International Nuclear Information System (INIS)

    The paper introduces the content of the recently started joint research project 'Development of LiDAR measurements for the German Offshore Test Site' which has the objective to support other research projects at the German offshore test site 'alpha ventus'. The project has started before the erection of the offshore wind farm and one aim is to give recommendations concerning LiDAR technology useable for offshore measurement campaigns and data analysis. The work is organized in four work packages. The work package LiDAR technology deals with the specification, acquisition and calibration of a commercial LiDAR system for the measurement campaigns. Power curve measurements are dedicated to power curve assessment with ground-based LiDAR using standard statistical methods. Additionally, it deals with the development of new methods for the measurement of non-steady short-term power curves. Wind field research aims at the development of wake loading simulation methods of wind turbines and the exploration of loading control strategies and nacelle-based wind field measurement techniques. Finally, dissemination of results to the industry takes place in work package Technology transfer

  12. ¿ES LA FAMILIA UNA INSTITUCIÓN NATURAL?

    Directory of Open Access Journals (Sweden)

    Juan Manuel Burgos Velasco

    2005-01-01

    Full Text Available El presente artículo analiza la descripción de la familia como institución natural. Para ello se establecen tres signifi cados del término naturaleza en la tradición aristotélica: 1 cosmológico; 2 fi losófi co restringido y 3 fi losófi co extendido o metafísico. El análisis muestra que los dos primeros signifi cados son reduccionistas y que, por lo tanto, también es reduccionista decir que la familia es una institución natural. Es, correcto, sin embargo, afi rmar que la familia es conforme a la naturaleza humana (significado 3 siempre que no se extraiga arbitrariamente de este término la dimensión cultural. Se señala, por fi n, que conceder importancia a este último aspecto es trascendental si se quiere estar en condiciones de infl uir en la batalla ideológica y sociológica que está teniendo lugar en torno al concepto de familia.

  13. High-precision DEM reconstruction based on airborne LiDAR point clouds

    Science.gov (United States)

    Xu, Jingzhong; Kou, Yuan; Wang, Jun

    2014-05-01

    Airborne LiDAR point clouds have become important data sources for DEM generation recently; however the problem of low precision and low efficiency in DEM production still exists. This paper proposes a new technical scheme for high-precision DEM production based on airborne LiDAR point clouds systematically. Firstly, an elevation and density analysis method is applied to filter out outliers. Secondly, ground points are detected by an improved filter algorithm based on the hierarchical smoothing method. Finally, feature lines are extracted by the planar surface fitting and intersecting method, and a simple data structure of feature lines preserved DEM is proposed to achieve reconstructing high accuracy DEM, combing feature lines with ground points. Experimental results show that the proposed scheme is able to compensate for deficiencies of existing DEM reconstruction techniques and can meet the needs of high precision DEM production based on LiDAR data.

  14. Classification of LiDAR data based on region segmentation and decision tree

    Science.gov (United States)

    Liu, Kai-si; Wang, Yan-bing; Gong, Hui-li

    2014-11-01

    Aiming at spatial characteristics and echo information of the LiDAR point cloud data, design a regional segmentation and decision tree combined lidar point data classification method. First, based on the continuity of the LiDAR point cloud to finish the experiment area's region segmentation. Then, statistics each area boundaries and internal the number of dihedral angle cosine, to draw a line chart. Using the intersection's cosine of line chart , and region segmentation's minimum height as threshold to determine the ground point and the non-ground points. Finally, statistics separately all LiDAR point data set's dihedral angle, echo times, echo intensity, mean elevation, four constraint information to build a decision tree to determine which type of feature vesting each divided region. Using classification confusion matrix to assess the classification's accuracy, overall accuracy is higher than 94%. Experimental results show that this method can effectively separate roads, trees, buildings and terrain.

  15. European LiDAR Mapping Forum Un report dal futuro del 3D intelligente

    Directory of Open Access Journals (Sweden)

    Redazione GEOmedia

    2013-03-01

    Full Text Available Circa 450 delegati provenienti da 45 paesi si sono riuniti per lo European LiDAR Mapping Forum (ELMFal Congress Palace nel centro di Salisburgo in Austria, dove si sono succedute presentazioni da parte diesperti leader a livello mondiale.Abstract About 450 delegates from 45 countries gathered for the European LiDAR Mapping Forum (ELMF at the Congress Palace in the center of Salzburg in Austria, with presentations by leading experts in the world. The topics on the use of LiDAR to support transport, urban modeling, coastal zone mapping, asset management, 3D visualization and GIS applications, have contributed to the success of the third ELMF (the first took place in 2012 from 4 to 5 December 2012. 

  16. Genetic linkage mapping in an F2 perennial ryegrass population using DArT markers

    DEFF Research Database (Denmark)

    Tomaszewski, Céline; Byrne, Stephen

    2012-01-01

    Perennial ryegrass is the principal forage grass species used in temperate agriculture. In recent years, significant efforts have been made to develop molecular marker strategies to allow cost-effective characterization of a large number of loci simultaneously. One such strategy involves using DArT markers, and a DArT array has recently been developed for the Lolium-Festuca complex. In this study, we report the first use of the DArTFest array to generate a genetic linkage map based on 326 markers in a Lolium perenne F2 population, consisting of 325 genotypes. For proof of concept, the map was used to identify QTL associated with differences in crown rust susceptibility, caused by the fungal biotroph, Puccinia coronata.

  17. Improving Species Diversity and Biomass Estimates of Tropical Dry Forests Using Airborne LiDAR

    Directory of Open Access Journals (Sweden)

    José Luis Hernández-Stefanoni

    2014-05-01

    Full Text Available The spatial distribution of plant diversity and biomass informs management decisions to maintain biodiversity and carbon stocks in tropical forests. Optical remotely sensed data is often used for supporting such activities; however, it is difficult to estimate these variables in areas of high biomass. New technologies, such as airborne LiDAR, have been used to overcome such limitations. LiDAR has been increasingly used to map carbon stocks in tropical forests, but has rarely been used to estimate plant species diversity. In this study, we first evaluated the effect of using different plot sizes and plot designs on improving the prediction accuracy of species richness and biomass from LiDAR metrics using multiple linear regression. Second, we developed a general model to predict species richness and biomass from LiDAR metrics for two different types of tropical dry forest using regression analysis. Third, we evaluated the relative roles of vegetation structure and habitat heterogeneity in explaining the observed patterns of biodiversity and biomass, using variation partition analysis and LiDAR metrics. The results showed that with increasing plot size, there is an increase of the accuracy of biomass estimations. In contrast, for species richness, the inclusion of different habitat conditions (cluster of four plots over an area of 1.0 ha provides better estimations. We also show that models of plant diversity and biomass can be derived from small footprint LiDAR at both local and regional scales. Finally, we found that a large portion of the variation in species richness can be exclusively attributed to habitat heterogeneity, while biomass was mainly explained by vegetation structure.

  18. Estimating stem volume and biomass of Pinus koraiensis using LiDAR data.

    Science.gov (United States)

    Kwak, Doo-Ahn; Lee, Woo-Kyun; Cho, Hyun-Kook; Lee, Seung-Ho; Son, Yowhan; Kafatos, Menas; Kim, So-Ra

    2010-07-01

    The objective of this study was to estimate the stem volume and biomass of individual trees using the crown geometric volume (CGV), which was extracted from small-footprint light detection and ranging (LiDAR) data. Attempts were made to analyze the stem volume and biomass of Korean Pine stands (Pinus koraiensis Sieb. et Zucc.) for three classes of tree density: low (240 N/ha), medium (370 N/ha), and high (1,340 N/ha). To delineate individual trees, extended maxima transformation and watershed segmentation of image processing methods were applied, as in one of our previous studies. As the next step, the crown base height (CBH) of individual trees has to be determined; information for this was found in the LiDAR point cloud data using k-means clustering. The LiDAR-derived CGV and stem volume can be estimated on the basis of the proportional relationship between the CGV and stem volume. As a result, low tree-density plots had the best performance for LiDAR-derived CBH, CGV, and stem volume (R (2) = 0.67, 0.57, and 0.68, respectively) and accuracy was lowest for high tree-density plots (R (2) = 0.48, 0.36, and 0.44, respectively). In the case of medium tree-density plots accuracy was R (2) = 0.51, 0.52, and 0.62, respectively. The LiDAR-derived stem biomass can be predicted from the stem volume using the wood basic density of coniferous trees (0.48 g/cm(3)), and the LiDAR-derived above-ground biomass can then be estimated from the stem volume using the biomass conversion and expansion factors (BCEF, 1.29) proposed by the Korea Forest Research Institute (KFRI). PMID:20182905

  19. Detection of large above ground biomass variability in lowland forest ecosystems by airborne LiDAR

    Directory of Open Access Journals (Sweden)

    J. Jubanski

    2012-08-01

    Full Text Available Quantification of tropical forest Above Ground Biomass (AGB over large areas as input for Reduced Emissions from Deforestation and forest Degradation (REDD+ projects and climate change models is challenging. This is the first study which attempts to estimate AGB and its variability across large areas of tropical lowland forests in Central Kalimantan (Indonesia through correlating airborne Light Detection and Ranging (LiDAR to forest inventory data. Two LiDAR height metrics were analysed and regression models could be improved through the use of LiDAR point densities as input (R2 = 0.88; n = 52. Surveying with a LiDAR point density per square meter of 2–4 resulted in the best cost-benefit ratio. We estimated AGB for 600 km of LiDAR tracks and showed that there exists a considerable variability of up to 140% within the same forest type due to varying environmental conditions. Impact from logging operations and the associated AGB losses dating back more than 10 yr could be assessed by LiDAR but not by multispectral satellite imagery. Comparison with a Landsat classification for a 1 million ha study area where AGB values were based on site specific field inventory data, regional literature estimates, and default values by the Intergovernmental Panel on Climate Change (IPCC showed an overestimation of 46%, 102%, and 137%, respectively. The results show that AGB overestimation may lead to wrong GHG emission estimates due to deforestation in climate models. For REDD+ projects this leads to inaccurate carbon stock estimates and consequently to significantly wrong REDD+ based compensation payments.

  20. Detailed Hydrographic Feature Extraction from High-Resolution LiDAR Data

    Energy Technology Data Exchange (ETDEWEB)

    Danny L. Anderson

    2012-05-01

    Detailed hydrographic feature extraction from high-resolution light detection and ranging (LiDAR) data is investigated. Methods for quantitatively evaluating and comparing such extractions are presented, including the use of sinuosity and longitudinal root-mean-square-error (LRMSE). These metrics are then used to quantitatively compare stream networks in two studies. The first study examines the effect of raster cell size on watershed boundaries and stream networks delineated from LiDAR-derived digital elevation models (DEMs). The study confirmed that, with the greatly increased resolution of LiDAR data, smaller cell sizes generally yielded better stream network delineations, based on sinuosity and LRMSE. The second study demonstrates a new method of delineating a stream directly from LiDAR point clouds, without the intermediate step of deriving a DEM. Direct use of LiDAR point clouds could improve efficiency and accuracy of hydrographic feature extractions. The direct delineation method developed herein and termed “mDn”, is an extension of the D8 method that has been used for several decades with gridded raster data. The method divides the region around a starting point into sectors, using the LiDAR data points within each sector to determine an average slope, and selecting the sector with the greatest downward slope to determine the direction of flow. An mDn delineation was compared with a traditional grid-based delineation, using TauDEM, and other readily available, common stream data sets. Although, the TauDEM delineation yielded a sinuosity that more closely matches the reference, the mDn delineation yielded a sinuosity that was higher than either the TauDEM method or the existing published stream delineations. Furthermore, stream delineation using the mDn method yielded the smallest LRMSE.

  1. Tree crown delineation from high resolution airborne LiDAR based on densities of high points :

    OpenAIRE

    Rahman, M. Z. A.; Gorte, B. G. H.

    2009-01-01

    Tree detection and tree crown delineation from Airborne LiDAR has been focusing mostly on utilizing the canopy height model (CHM). This paper presents a method for individual tree crown delineation based on densities of high points (DHP) from the high resolution Airborne LiDAR. The DHP method relies on the fact that the density of received laser pulses above a certain height is high at the centre of a tree crown and decreases towards the edge of the crown. In this study, the performance of th...

  2. MKENO-DAR: a direct angular representation Monte Carlo code for criticality safety analysis

    International Nuclear Information System (INIS)

    Improving the Monte Carlo code MULTI-KENO, the MKENO-DAR (Direct Angular Representation) code has been developed for criticality safety analysis in detail. A function was added to MULTI-KENO for representing anisotropic scattering strictly. With this function, the scattering angle of neutron is determined not by the average scattering angle ?-bar of the Pl Legendre polynomial but by the random work operation using probability distribution function produced with the higher order Legendre polynomials. This code is avilable for the FACOM-M380 computer. This report is a computer code manual for MKENO-DAR. (author)

  3. Automatic detection of gravel bars in a river channel from airborne LiDAR-derived DTM

    OpenAIRE

    Pe?nard, L.; Morel, M.

    2012-01-01

    Airborne Laser Scanning or LiDAR data are widely used nowadays in river valleys for topography and hydro-morphology. However, the large data sets of unprocessed 3D point clouds require some challenging treatment and end-users may prefer to deal with DTMs (Digital Terrain Models) derived from LiDAR surveys. Without any complementary data (such as field survey or photographs) detecting position and shape of gravel bars in a river is a demanding task, especially if done manually. This paper ...

  4. Using airborne LiDAR and USGS DEM data for assessing rock glaciers and glaciers

    Science.gov (United States)

    Janke, Jason R.

    2013-08-01

    Varying topographic and geologic conditions affect the location of rock glaciers. Despite being found worldwide, rock glaciers are often confused with glacier counterparts or other periglacial landforms. Light detection and ranging (LiDAR) data, because of its accuracy and resolution, may help the assessment of topographic variables needed to form rock glaciers or help reveal unique characteristics to enhance regional, automatic mapping. The objectives of this paper are to compare the elevation, slope, aspect, hillshade, and curvature for 1 m LiDAR and 10 m US Geological Survey (USGS) Digital Elevation Models (DEMs) from the Andrews and Taylor Glaciers with the Taylor Rock Glacier in Colorado. The utility of these data sources will be assessed for landform discrimination and to evaluate the uncertainty between the DEMs. According to the LiDAR data, the Taylor Rock Glacier exists at a lower elevation and has a gentler slope compared to the glaciers. Each landform has steep areas from which snow and debris are delivered. The Andrews Glacier has the most northern aspect, which helps maintain it through snow accumulation and reduced insolation. Glaciers exhibit a concave mean curvature, whereas the Taylor Rock Glacier has a convex mean curvature. The fine resolution of the LiDAR data clearly identifies some distinct characteristics. On the Taylor Rock Glacier, ridges, furrows, and a pronounced front slope were easily identifiable on the LiDAR DEM, whereas crevasses, the boundary between snow and debris covered surfaces, and a lateral moraine were detectable near the Andrews Glacier. The accuracy assessment revealed that at a common 10 m resolution, the USGS DEM estimated a maximum elevation about 150 m greater compared to the LiDAR data in areas of rugged topography surrounding the landforms. A comparison of root mean squared errors (RMSE) between the LiDAR and USGS DEMs showed that the Taylor Rock Glacier has the lowest RMSE for the elevation and the curvature variables. As a result, readily available USGS DEMs may better for analysis to characterize the topographic setting of landforms at the regional scale. At the fine scale, however, the micro-topography of rock glaciers is illuminated much more clearly on the LiDAR data, making it an ideal, yet costly source, for feature extraction.

  5. Wa-LiD: A new LiDAR simulator for waters

    OpenAIRE

    Abdallah, H.; Baghdadi, N.; Bailly, J. S.; Pastol, Y.; Fabre, F.

    2012-01-01

    A simulator (Wa-LiD) was developed to simulate the reflection of LiDAR waveforms from water across visible wavelengths. The specific features of the simulator include (i) a geometrical representation of the water surface properties, (ii) the use of laws of radiative transfer in water adjusted for wavelength and the water’s physical properties, and (iii) modelling of detection noise and signal level due to solar radiation. A set of simulated waveforms was compared with observed LiDAR wav...

  6. The use of airborne LiDAR data for the analysis of debris flow events in Switzerland

    Directory of Open Access Journals (Sweden)

    C. Scheidl

    2008-10-01

    Full Text Available A methodology of magnitude estimates for debris flow events is described using airborne LiDAR data. Light Detection And Ranging (LiDAR is a widely used technology to generate digital elevation information. LiDAR data in alpine regions can be obtained by several commercial companies where the automated filtering process is proprietary and varies from companies to companies. This study describes the analysis of geomorphologic changes using digital terrain models derived from commercial LiDAR data. The estimation of the deposition volumes is based on two digital terrain models covering the same area but differing in their time of survey. In this study two surveyed deposition areas of debris flows, located in the canton of Berne, Switzerland, were chosen as test cases. We discuss different grid interpolating techniques, other preliminary work and the accuracy of the used LiDAR data and volume estimates.

  7. Semi-Supervised Methods to Identify Individual Crowns of Lowland Tropical Canopy Species Using Imaging Spectroscopy and LiDAR

    Directory of Open Access Journals (Sweden)

    Gregory P. Asner

    2012-08-01

    Full Text Available Our objective is to identify and map individuals of nine tree species in a Hawaiian lowland tropical forest by comparing the performance of a variety of semi-supervised classifiers. A method was adapted to process hyperspectral imagery, LiDAR intensity variables, and LiDAR-derived canopy height and use them to assess the identification accuracy. We found that semi-supervised Support Vector Machine classification using tensor summation kernel was superior to supervised classification, with demonstrable accuracy for at least eight out of nine species, and for all combinations of data types tested. We also found that the combination of hyperspectral imagery and LiDAR data usually improved species classification. Both LiDAR intensity and LiDAR canopy height proved useful for classification of certain species, but the improvements varied depending upon the species in question. Our results pave the way for target-species identification in tropical forests and other ecosystems.

  8. Was bedeutet es, Rechte zu haben?

    Directory of Open Access Journals (Sweden)

    Birnbacher, Dieter

    2012-12-01

    Full Text Available Dieser Artikel bietet eine Einführung in die Sprache der Rechte und in die Rolle, die Rechte in Ethik und Recht spielen, unter besondererBezugnahme auf die Rechte von Kindern. Es zeichnet sich ab, dass es eine ganze Reihe von Funktionen gibt, die für die Sprache der Rechtecharakteristisch sind, sowohl in der Ethik als auch in der Rechtswissenschaft. Viele davon bieten die Möglichkeit, den Appell an moralische und juridische Prinzipien zu stärken, während andere Fallen stellen, die es zu vermeiden gilt. Zum Schluss werden zwei theoretische Fragen, die Rechte aufwerfen, behandelt: Zum einen, ob das Konzept der Rechte ohne Verlust durch das Konzept der Pflichten ersetzt werden kann; zum anderen, ob Rechte als soziale Konstrukte, die von Verpflichtungen abgeleitet sind, gesehen werden sollten, oder ob es plausibler ist, die Prioritätenfolge umzudrehen.

  9. ¿Es la muerte importante para la vida?

    OpenAIRE

    Rez, Fernando Iv U. E. N. Flores P. U. E.

    2002-01-01

    El fenómeno de muerte celular programada, o apoptosis, es actualmente uno de los más estudiados en el campo de la biomedicina; su importancia radica en que varias enfermedades, que afectan tanto al hombre como a los animales, son causadas por una alteración en este mecanismo fisiológico tan relevante, a tal grado que sin la existencia de este fenómeno fisiológico, la vida, como actualmente se conoce no sería posible. El propósito del presente trabajo es definir el fenómen...

  10. Genetics and Human Agency: Comment on Dar-Nimrod and Heine (2011)

    Science.gov (United States)

    Turkheimer, Eric

    2011-01-01

    Dar-Nimrod and Heine (2011) decried genetic essentialism without denying the importance of genetics in the genesis of human behavior, and although I agree on both counts, a deeper issue remains unaddressed: how should we adjust our cognitions about our own behavior in light of genetic influence, or is it perhaps not necessary to take genetics into…

  11. Habitat Classification of Temperate Marine Macroalgal Communities Using Bathymetric LiDAR

    Directory of Open Access Journals (Sweden)

    Richard Zavalas

    2014-03-01

    Full Text Available Here, we evaluated the potential of using bathymetric Light Detection and Ranging (LiDAR to characterise shallow water (<30 m benthic habitats of high energy subtidal coastal environments. Habitat classification, quantifying benthic substrata and macroalgal communities, was achieved in this study with the application of LiDAR and underwater video groundtruth data using automated classification techniques. Bathymetry and reflectance datasets were used to produce secondary terrain derivative surfaces (e.g., rugosity, aspect that were assumed to influence benthic patterns observed. An automated decision tree classification approach using the Quick Unbiased Efficient Statistical Tree (QUEST was applied to produce substrata, biological and canopy structure habitat maps of the study area. Error assessment indicated that habitat maps produced were primarily accurate (>70%, with varying results for the classification of individual habitat classes; for instance, producer accuracy for mixed brown algae and sediment substrata, was 74% and 93%, respectively. LiDAR was also successful for differentiating canopy structure of macroalgae communities (i.e., canopy structure classification, such as canopy forming kelp versus erect fine branching algae. In conclusion, habitat characterisation using bathymetric LiDAR provides a unique potential to collect baseline information about biological assemblages and, hence, potential reef connectivity over large areas beyond the range of direct observation. This research contributes a new perspective for assessing the structure of subtidal coastal ecosystems, providing a novel tool for the research and management of such highly dynamic marine environments.

  12. Airborne hyperspectral and LiDAR data integration for weed detection

    Science.gov (United States)

    Tamás, János; Lehoczky, Éva; Fehér, János; Fórián, Tünde; Nagy, Attila; Bozsik, Éva; Gálya, Bernadett; Riczu, Péter

    2014-05-01

    Agriculture uses 70% of global available fresh water. However, ca. 50-70% of water used by cultivated plants, the rest of water transpirated by the weeds. Thus, to define the distribution of weeds is very important in precision agriculture and horticulture as well. To survey weeds on larger fields by traditional methods is often time consuming. Remote sensing instruments are useful to detect weeds in larger area. In our investigation a 3D airborne laser scanner (RIEGL LMS-Q680i) was used in agricultural field near Sopron to scouting weeds. Beside the airborne LiDAR, hyperspectral imaging system (AISA DUAL) and air photos helped to investigate weed coverage. The LiDAR survey was carried out at early April, 2012, before sprouting of cultivated plants. Thus, there could be detected emerging of weeds and direction of cultivation. However airborne LiDAR system was ideal to detect weeds, identification of weeds at species level was infeasible. Higher point density LiDAR - Terrestrial laser scanning - systems are appropriate to distinguish weed species. Based on the results, laser scanner is an effective tool to scouting of weeds. Appropriate weed detection and mapping systems could contribute to elaborate water and herbicide saving management technique. This publication was supported by the OTKA project K 105789.

  13. Draft Genome Sequence of Bacillus thuringiensis Strain DAR 81934, Which Exhibits Molluscicidal Activity

    OpenAIRE

    Wang, Aisuo; Pattemore, Julie; Ash, Gavin; Williams, Angela; Hane, James

    2013-01-01

    Bacillus thuringiensis has been widely used as a biopesticide for a long time. Its molluscicidal activity, however, is rarely realized. Here, we report the genome sequence of B. thuringiensis strain DAR 81934, a strain with molluscicidal activity against the pest snail Cernuella virgata.

  14. Genetic Essentialism, Neuroessentialism, and Stigma: Commentary on Dar-Nimrod and Heine (2011)

    Science.gov (United States)

    Haslam, Nick

    2011-01-01

    Dar-Nimrod and Heine (2011) presented a masterfully broad review of the implications of genetic essentialism for understandings of human diversity. This commentary clarifies the reasons that essentialist thinking has problematic social consequences and links genetic forms of essentialism to those invoking neural essences. The mounting evidence…

  15. A comparison of two open source LiDAR surface classification algorithms

    Science.gov (United States)

    With the progression of LiDAR (Light Detection and Ranging) towards a mainstream resource management tool, it has become necessary to understand how best to process and analyze the data. While most ground surface identification algorithms remain proprietary and have high purchase costs; a few are op...

  16. a Data Driven Method for Building Reconstruction from LiDAR Point Clouds

    Science.gov (United States)

    Sajadian, M.; Arefi, H.

    2014-10-01

    Airborne laser scanning, commonly referred to as LiDAR, is a superior technology for three-dimensional data acquisition from Earth's surface with high speed and density. Building reconstruction is one of the main applications of LiDAR system which is considered in this study. For a 3D reconstruction of the buildings, the buildings points should be first separated from the other points such as; ground and vegetation. In this paper, a multi-agent strategy has been proposed for simultaneous extraction and segmentation of buildings from LiDAR point clouds. Height values, number of returned pulse, length of triangles, direction of normal vectors, and area are five criteria which have been utilized in this step. Next, the building edge points are detected using a new method named "Grid Erosion". A RANSAC based technique has been employed for edge line extraction. Regularization constraints are performed to achieve the final lines. Finally, by modelling of the roofs and walls, 3D building model is reconstructed. The results indicate that the proposed method could successfully extract the building from LiDAR data and generate the building models automatically. A qualitative and quantitative assessment of the proposed method is then provided.

  17. Engineering monitoring of rockfall hazards along transportation corridors: using mobile terrestrial LiDAR

    Directory of Open Access Journals (Sweden)

    M. Lato

    2009-06-01

    Full Text Available Geotechnical hazards along linear transportation corridors are challenging to identify and often require constant monitoring. Inspecting corridors using traditional, manual methods requires the engineer to be unnecessarily exposed to the hazard. It also requires closure of the corridor to ensure safety of the worker from passing vehicles. This paper identifies the use of mobile terrestrial LiDAR data as a compliment to traditional field methods. Mobile terrestrial LiDAR is an emerging remote data collection technique capable of generating accurate fully three-dimensional virtual models while driving at speeds up to 100 km/h. Data is collected from a truck that causes no delays to active traffic nor does it impede corridor use. These resultant georeferenced data can be used for geomechanical structural feature identification and kinematic analysis, rockfall path identification and differential monitoring of rock movement or failure over time. Comparisons between mobile terrestrial and static LiDAR data collection and analysis are presented. As well, detailed discussions on workflow procedures for possible implementation are discussed. Future use of mobile terrestrial LiDAR data for corridor analysis will focus on repeated surveys and developing dynamic four-dimensional models, higher resolution data collection. As well, computationally advanced, spatially accurate, geomechanically controlled three-dimensional rockfall simulations should be investigated.

  18. Registration of optical imagery and LiDAR data using an inherent geometrical constraint.

    Science.gov (United States)

    Zhang, Wuming; Zhao, Jing; Chen, Mei; Chen, Yiming; Yan, Kai; Li, Linyuan; Qi, Jianbo; Wang, Xiaoyan; Luo, Jinghui; Chu, Qing

    2015-03-23

    A novel method for registering imagery with Light Detection And Ranging (LiDAR) data is proposed. It is based on the phenomenon that the back-projection of LiDAR point cloud of an object should be located within the object boundary in the image. Using this inherent geometrical constraint, the registration parameters computation of both data sets only requires LiDAR point clouds of several objects and their corresponding boundaries in the image. The proposed registration method comprises of four steps: point clouds extraction, boundary extraction, back-projection computation and registration parameters computation. There are not any limitations on the geometrical and spectral properties of the object. So it is suitable not only for structured scenes with man-made objects but also for natural scenes. Moreover, the proposed method based on the inherent geometrical constraint can register two data sets derived from different parts of an object. It can be used to co-register TLS (Terrestrial Laser Scanning) LiDAR point cloud and UAV (Unmanned aerial vehicle) image, which are obtaining more attention in the forest survey application. Using initial registration parameters comparable to POS (position and orientation system) accuracy, the performed experiments validated the feasibility of the proposed registration method. PMID:25837107

  19. Sensitivity analysis of simulated bathymetric LiDAR waveforms according to sensor and river parameters variability

    Science.gov (United States)

    Bailly, J.; Abdallah, H.; Baghdadi, N.; Saint-Geours, N.

    2010-12-01

    LiDAR (Light Detection and Ranging) can be used as a ranging system using electromagnetic waves in the optical domain. LiDAR airborne or satellite sensors are promising techniques for river bathymetry and water surface altimetry considering its potential accuracy, its high spatial density and resolution. When considering physics of LiDAR, many factors coming from sensor characteristics and optical phenomena interacting during the signal transfer at media interfaces are conditioning LiDAR signals, i.e. waveforms. Waveforms are the registered signals in LiDAR from which, hydrological variables, as surface water altimetry, bathymetry, are retrieved. To move forward in the LIDAR airborne and satellite sensors capabilities for river monitoring, a modelling tool extending different existing radiative transfer models has been developed. This model allows the simulation of LiDAR data from a set of instrumental parameters and a representative collection of fluvial target for laser beam (water turbidity, river bottom reflectivity, etc). Due to the large numbers of parameters in the modelling and their natural range of variation, one of the questions is which of those parameters have the most impact, and those who have a negligible effect on returned waveform? And consequently, which of them most impact the accuracy of the retrieved hydrological variables from waveforms? In order to assess the robustness of the proposed model, to look for parsimony and to identify the key sensor parameters, a study of the model sensitivity to different media characteristics (surface reflection, absorption, scattering, bottom Albedo, etc) and sensor parameters (wavelength, pulse width, transmitted power, etc) is performed. Due to the complexity of the LiDAR waveform modelling, we used a sensitivity analysis method based on variance decomposition (Sobol) and Latin hypercube random sampling design in factor variation domains. As output model are waveforms, i.e. temporal signal, we used the specific Sobol framework proposed by Lamboni (2010). Results are the synthetic Sobol indices showing which factors are highly conditioning waveforms and others that can be neglected in the modelling. By pursuing the sensitivity analysis up to the waveform inversion (Gaussian fitting) to retrieve bathymetry, sensor and river parameters which are the more impacting bathymetry accuracy can also been hierarchically identified in this framework.

  20. Effects of atmospheric stability on the evolution of wind turbine wakes: Volumetric LiDAR scans

    Science.gov (United States)

    Valerio Iungo, Giacomo; Porté-Agel, Fernando

    2014-05-01

    Aerodynamic optimization of wind farm layout is a fundamental task to reduce wake effects on downstream wind turbines, thus to maximize wind power harvesting. However, downstream evolution and recovery of wind turbine wakes are strongly affected by the characteristics of the incoming atmospheric boundary layer (ABL) flow, like the vertical profiles of the mean wind velocity and the turbulence intensity, which are in turn affected by the ABL stability regime. Therefore, the characterization of the variability of wind turbine wakes under different ABL stability regimes becomes fundamental to better predict wind power harvesting and improve wind farm efficiency. To this aim, wind velocity measurements of the wake produced by a 2 MW Enercon E-70 wind turbine were performed with three scanning Doppler wind Light Detection and Ranging (LiDAR) instruments. One LiDAR was typically devoted to the characterization of the incoming wind, in particular wind velocity, shear and turbulence intensity at the height of the rotor disc. The other two LiDARs performed scans in order to characterize the wake velocity field produced by the tested wind turbine. The main challenge in performing field measurements of wind turbine wakes is represented by the varying wind conditions, and by the consequent adjustments of the turbine yaw angle needed to maximize power production. Consequently, taking into account possible variations of the relative position between LiDAR measurement volume and wake location, different LiDAR measurement procedures were carried out in order to perform 2-D and 3-D characterizations of the mean wake velocity field. However, larger measurement volumes and higher spatial resolution require longer sampling periods; thus, to investigate wake turbulence tests were also performed by staring the LiDAR laser beam over fixed directions and with the maximum sampling frequency. Furthermore, volumetric scans of the wind turbine wake were performed under different wind conditions via two simultaneous LiDARs. Through the evaluation of the minimum wake velocity deficit as a function of the downstream distance, it is shown that the stability regime of the ABL has a significant effect on the wake evolution; specifically the wake recovers faster under convective conditions. This result suggests that atmospheric inflow conditions, and particularly thermal stability, should be considered for improved wake models and predictions of wind power harvesting.

  1. Using satellite and airborne LiDAR to model woodpecker habitat occupancy at the landscape scale.

    Science.gov (United States)

    Vierling, Lee A; Vierling, Kerri T; Adam, Patrick; Hudak, Andrew T

    2013-01-01

    Incorporating vertical vegetation structure into models of animal distributions can improve understanding of the patterns and processes governing habitat selection. LiDAR can provide such structural information, but these data are typically collected via aircraft and thus are limited in spatial extent. Our objective was to explore the utility of satellite-based LiDAR data from the Geoscience Laser Altimeter System (GLAS) relative to airborne-based LiDAR to model the north Idaho breeding distribution of a forest-dependent ecosystem engineer, the Red-naped sapsucker (Sphyrapicus nuchalis). GLAS data occurred within ca. 64 m diameter ellipses spaced a minimum of 172 m apart, and all occupancy analyses were confined to this grain scale. Using a hierarchical approach, we modeled Red-naped sapsucker occupancy as a function of LiDAR metrics derived from both platforms. Occupancy models based on satellite data were weak, possibly because the data within the GLAS ellipse did not fully represent habitat characteristics important for this species. The most important structural variables influencing Red-naped Sapsucker breeding site selection based on airborne LiDAR data included foliage height diversity, the distance between major strata in the canopy vertical profile, and the vegetation density near the ground. These characteristics are consistent with the diversity of foraging activities exhibited by this species. To our knowledge, this study represents the first to examine the utility of satellite-based LiDAR to model animal distributions. The large area of each GLAS ellipse and the non-contiguous nature of GLAS data may pose significant challenges for wildlife distribution modeling; nevertheless these data can provide useful information on ecosystem vertical structure, particularly in areas of gentle terrain. Additional work is thus warranted to utilize LiDAR datasets collected from both airborne and past and future satellite platforms (e.g. GLAS, and the planned IceSAT2 mission) with the goal of improving wildlife modeling for more locations across the globe. PMID:24324655

  2. Object-Based Land Use Classification using Airborne LiDAR

    Science.gov (United States)

    Antonarakis, A. S.; Richards, K. S.; Brasington, J.

    2007-12-01

    Better information on roughness of various types of vegetation is needed for use in resistance equations and eventually in flood modelling. These types include woody riparian species with different structural characteristics. Remote Sensing information such as 3D point cloud data from LiDAR can be used as a tool for extracting simple roughness information relevant for the condition of below canopy flow, as well as roughness relevant for more complex tree morphology that affects the flow when it enters the canopy levels. A strategy for extracting roughness parameters from remote sensing techniques is to use a data fusion object classification model. This means that multiple datasets such as LiDAR, digital aerial photography, ground data and satellite data can be combined to produce roughness parameters estimated for different vegetative patches, which can subsequently be mapped spatially using a classification methodology. Airborne LiDAR is used in this study in order to classify forest and ground types quickly and efficiently without the need for manipulating multispectral image files. LiDAR has the advantage of being able to create elevation surfaces that are in 3D, while also having information on LiDAR intensity values, thus it is a spatial and spectral segmentation tool. This classification method also uses point distribution frequency criteria to differentiate between land cover types. The classification of three meanders of the Garonne and Allier rivers in France has demonstrated overall classification accuracies of 95%. Five types of riparian forest were classified with accuracies between 66-98%. These forest types included planted and natural forest stands of different ages. Classifications of short vegetation and bare earth also produced high accuracies averaging above 90%.

  3. A universal airborne LiDAR approach for tropical forest carbon mapping.

    Science.gov (United States)

    Asner, Gregory P; Mascaro, Joseph; Muller-Landau, Helene C; Vieilledent, Ghislain; Vaudry, Romuald; Rasamoelina, Maminiaina; Hall, Jefferson S; van Breugel, Michiel

    2012-04-01

    Airborne light detection and ranging (LiDAR) is fast turning the corner from demonstration technology to a key tool for assessing carbon stocks in tropical forests. With its ability to penetrate tropical forest canopies and detect three-dimensional forest structure, LiDAR may prove to be a major component of international strategies to measure and account for carbon emissions from and uptake by tropical forests. To date, however, basic ecological information such as height-diameter allometry and stand-level wood density have not been mechanistically incorporated into methods for mapping forest carbon at regional and global scales. A better incorporation of these structural patterns in forests may reduce the considerable time needed to calibrate airborne data with ground-based forest inventory plots, which presently necessitate exhaustive measurements of tree diameters and heights, as well as tree identifications for wood density estimation. Here, we develop a new approach that can facilitate rapid LiDAR calibration with minimal field data. Throughout four tropical regions (Panama, Peru, Madagascar, and Hawaii), we were able to predict aboveground carbon density estimated in field inventory plots using a single universal LiDAR model (r ( 2 ) = 0.80, RMSE = 27.6 Mg C ha(-1)). This model is comparable in predictive power to locally calibrated models, but relies on limited inputs of basal area and wood density information for a given region, rather than on traditional plot inventories. With this approach, we propose to radically decrease the time required to calibrate airborne LiDAR data and thus increase the output of high-resolution carbon maps, supporting tropical forest conservation and climate mitigation policy. PMID:22033763

  4. Mapping the Risk of Forest Wind Damage Using Airborne Scanning LiDAR

    Science.gov (United States)

    Saarinen, N.; Vastaranta, M.; Honkavaara, E.; Wulder, M. A.; White, J. C.; Litkey, P.; Holopainen, M.; Hyyppä, J.

    2015-03-01

    Wind damage is known for causing threats to sustainable forest management and yield value in boreal forests. Information about wind damage risk can aid forest managers in understanding and possibly mitigating damage impacts. The objective of this research was to better understand and quantify drivers of wind damage, and to map the probability of wind damage. To accomplish this, we used open-access airborne scanning light detection and ranging (LiDAR) data. The probability of wind-induced forest damage (PDAM) in southern Finland (61°N, 23°E) was modelled for a 173 km2 study area of mainly managed boreal forests (dominated by Norway spruce and Scots pine) and agricultural fields. Wind damage occurred in the study area in December 2011. LiDAR data were acquired prior to the damage in 2008. High spatial resolution aerial imagery, acquired after the damage event (January, 2012) provided a source of model calibration via expert interpretation. A systematic grid (16 m x 16 m) was established and 430 sample grid cells were identified systematically and classified as damaged or undamaged based on visual interpretation using the aerial images. Potential drivers associated with PDAM were examined using a multivariate logistic regression model. Risk model predictors were extracted from the LiDAR-derived surface models. Geographic information systems (GIS) supported spatial mapping and identification of areas of high PDAM across the study area. The risk model based on LiDAR data provided good agreement with detected risk areas (73 % with kappa-value 0,47). The strongest predictors in the risk model were mean canopy height and mean elevation. Our results indicate that open-access LiDAR data sets can be used to map the probability of wind damage risk without field data, providing valuable information for forest management planning.

  5. Capabilities of the bathymetric Hawk Eye LiDAR for coastal habitat mapping: A case study within a Basque estuary

    Science.gov (United States)

    Chust, Guillem; Grande, Maitane; Galparsoro, Ibon; Uriarte, Adolfo; Borja, Ángel

    2010-10-01

    The bathymetric LiDAR system is an airborne laser that detects sea bottom at high vertical and horizontal resolutions in shallow coastal waters. This study assesses the capabilities of the airborne bathymetric LiDAR sensor (Hawk Eye system) for coastal habitat mapping in the Oka estuary (within the Biosphere Reserve of Urdaibai, SE Bay of Biscay, northern Spain), where water conditions are moderately turbid. Three specific objectives were addressed: 1) to assess the data quality of the Hawk Eye LiDAR, both for terrestrial and subtidal zones, in terms of height measurement density, coverage, and vertical accuracy; 2) to compare bathymetric LiDAR with a ship-borne multibeam echosounder (MBES) for different bottom types and depth ranges; and 3) to test the discrimination potential of LiDAR height and reflectance information, together with multi-spectral imagery (three visible and near infrared bands), for the classification of 22 salt marsh and rocky shore habitats, covering supralittoral, intertidal and subtidal zones. The bathymetric LiDAR Hawk Eye data enabled the generation of a digital elevation model (DEM) of the Oka estuary, at 2 m of horizontal spatial resolution in the terrestrial zone (with a vertical accuracy of 0.15 m) and at 4 m within the subtidal, extending a water depth of 21 m. Data gaps occurred in 14.4% of the area surveyed with the LiDAR (13.69 km 2). Comparison of the LiDAR system and the MBES showed no significant mean difference in depth. However, the Root Mean Square error of the former was high (0.84 m), especially concentrated upon rocky (0.55-1.77 m) rather than in sediment bottoms (0.38-0.62 m). The potential of LiDAR topographic variables and reflectance alone for discriminating 15 intertidal and submerged habitats was low (with overall classification accuracy between 52.4 and 65.4%). In particular, reflectance retrieved for this case study has been found to be not particularly useful for classification purposes. The combination of the LiDAR-based DEM and derived topographical features with the near infrared and visible bands has permitted the mapping of 22 supralittoral, intertidal and subtidal habitats of the Oka estuary, with high overall classification accuracies of between 84.5% and 92.1%, using the maximum likelihood algorithm. The airborne bathymetric Hawk Eye LiDAR, although somewhat limited by water turbidity and wave breaking, provides unique height information obscured from topographic LiDAR and acoustic systems, together with an improvement of the habitat mapping reliability in the complex and dynamic coastal fringe.

  6. DArT markers: diversity analyses, genomes comparison, mapping and integration with SSR markers in Triticum monococcum

    Directory of Open Access Journals (Sweden)

    Huttner Eric

    2009-09-01

    Full Text Available Abstract Background Triticum monococcum (2n = 2x = 14 is an ancient diploid wheat with many useful traits and is used as a model for wheat gene discovery. DArT (Diversity Arrays Technology employs a hybridisation-based approach to type thousands of genomic loci in parallel. DArT markers were developed for T. monococcum to assess genetic diversity, compare relationships with hexaploid genomes, and construct a genetic linkage map integrating DArT and microsatellite markers. Results A DArT array, consisting of 2304 hexaploid wheat, 1536 tetraploid wheat, 1536 T. monococcum as well as 1536 T. boeoticum representative genomic clones, was used to fingerprint 16 T. monococcum accessions of diverse geographical origins. In total, 846 polymorphic DArT markers were identified, of which 317 were of T. monococcum origin, 246 of hexaploid, 157 of tetraploid, and 126 of T. boeoticum genomes. The fingerprinting data indicated that the geographic origin of T. monococcum accessions was partially correlated with their genetic variation. DArT markers could also well distinguish the genetic differences amongst a panel of 23 hexaploid wheat and nine T. monococcum genomes. For the first time, 274 DArT markers were integrated with 82 simple sequence repeat (SSR and two morphological trait loci in a genetic map spanning 1062.72 cM in T. monococcum. Six chromosomes were represented by single linkage groups, and chromosome 4Am was formed by three linkage groups. The DArT and SSR genetic loci tended to form independent clusters along the chromosomes. Segregation distortion was observed for one third of the DArT loci. The Ba (black awn locus was refined to a 23.2 cM region between the DArT marker locus wPt-2584 and the microsatellite locus Xgwmd33 on 1Am; and the Hl (hairy leaf locus to a 4.0 cM region between DArT loci 376589 and 469591 on 5Am. Conclusion DArT is a rapid and efficient approach to develop many new molecular markers for genetic studies in T. monococcum. The constructed genetic linkage map will facilitate localisation and map-based cloning of genes of interest, comparative mapping as well as genome organisation and evolution studies between this ancient diploid species and other crops.

  7. A LiDAR-based approach for a multi-purpose characterization of Alpine forests: an Italian case study

    OpenAIRE

    Alberti G; Boscutti F; Pirotti F; Bertacco C; De Simon G; Sigura M; Cazorzi F; Bonfanti P

    2013-01-01

    Several studies have verified the suitability of LiDAR for the estimation of forest metrics over large areas. In the present study we used LiDAR as support for the characterization of structure, volume, biomass and naturalistic value in mixed-coniferous forests of the Alpine region. Stem density, height and structure in the test plots were derived using a mathematical morphology function applied directly on the LiDAR point cloud. From these data, digital maps describing the horizontal and ver...

  8. Analysis of the Influence of Plot Size and LiDAR Density on Forest Structure Attribute Estimates

    OpenAIRE

    Ruiz, Luis A.; Txomin Hermosilla; Francisco Mauro; Miguel Godino

    2014-01-01

    This paper assesses the combined effect of field plot size and LiDAR density on the estimation of four forest structure attributes: volume, total biomass, basal area and canopy cover. A total of 21 different plot sizes were considered, obtained by decreasing the field measured plot radius value from 25 to 5 m with regular intervals of 1 m. LiDAR data densities were simulated by randomly removing LiDAR pulses until reaching nine different density values. In order to avoid influence of the digi...

  9. Quantifying spatial distribution of snow depth errors from LiDAR using Random Forests

    Science.gov (United States)

    Tinkham, W.; Smith, A. M.; Marshall, H.; Link, T. E.; Falkowski, M. J.; Winstral, A. H.

    2013-12-01

    There is increasing need to characterize the distribution of snow in complex terrain using remote sensing approaches, especially in isolated mountainous regions that are often water-limited, the principal source of terrestrial freshwater, and sensitive to climatic shifts and variations. We apply intensive topographic surveys, multi-temporal LiDAR, and Random Forest modeling to quantify snow volume and characterize associated errors across seven land cover types in a semi-arid mountainous catchment at a 1 and 4 m spatial resolution. The LiDAR-based estimates of both snow-off surface topology and snow depths were validated against ground-based measurements across the catchment. Comparison of LiDAR-derived snow depths to manual snow depth surveys revealed that LiDAR based estimates were more accurate in areas of low lying vegetation such as shrubs (RMSE = 0.14 m) as compared to areas consisting of tree cover (RMSE = 0.20-0.35 m). The highest errors were found along the edge of conifer forests (RMSE = 0.35 m), however a second conifer transect outside the catchment had much lower errors (RMSE = 0.21 m). This difference is attributed to the wind exposure of the first site that led to highly variable snow depths at short spatial distances. The Random Forest modeled errors deviated from the field measured errors with a RMSE of 0.09-0.34 m across the different cover types. Results show that snow drifts, which are important for maintaining spring and summer stream flows and establishing and sustaining water-limited plant species, contained 30 × 5-6% of the snow volume while only occupying 10% of the catchment area similar to findings by prior physically-based modeling approaches. This study demonstrates the potential utility of combining multi-temporal LiDAR with Random Forest modeling to quantify the distribution of snow depth with a reasonable degree of accuracy. Future work could explore the utility of Terrestrial LiDAR Scanners to produce validation of snow-on surface elevations.

  10. Development of a pit filling algorithm for LiDAR canopy height models

    Science.gov (United States)

    Ben-Arie, Joshua R.; Hay, Geoffrey J.; Powers, Ryan P.; Castilla, Guillermo; St-Onge, Benoît

    2009-09-01

    LiDAR canopy height models (CHMs) can exhibit unnatural looking holes or pits, i.e., pixels with a much lower digital number than their immediate neighbors. These artifacts may be caused by a combination of factors, from data acquisition to post-processing, that not only result in a noisy appearance to the CHM but may also limit semi-automated tree-crown delineation and lead to errors in biomass estimates. We present a highly effective semi-automated pit filling algorithm that interactively detects data pits based on a simple user-defined threshold, and then fills them with a value derived from their neighborhood. We briefly describe this algorithm and its graphical user interface, and show its result in a LiDAR CHM populated with data pits. This method can be rapidly applied to any CHM with minimal user interaction. Visualization confirms that our method effectively and quickly removes data pits.

  11. Characterization of the OPAL obscurant penetrating LiDAR in various degraded visual environments

    Science.gov (United States)

    Trickey, Evan; Church, Philip; Cao, Xiaoying

    2013-05-01

    The OPAL obscurant penetrating LiDAR was developed by Neptec and characterized in various degraded visual environments (DVE) over the past five years. Quantitative evaluations of obscurant penetration were performed using the Defence RD Canada - Valcartier (DRDC Valcartier) instrumented aerosol chamber for obscurants such as dust and fog. Experiments were done with the sensor both at a standoff distance and totally engulfed in the obscurants. Field trials were also done to characterize the sensor in snow conditions and in smoke. Finally, the OPAL was also mounted on a Bell 412 helicopter to characterize its dust penetration capabilities, in environment such as Yuma Proving Ground. The paper provides a summary of the results of the OPAL evaluations demonstrating it to be a true "see through" obscurant penetrating LiDAR and explores commercial applications of the technology.

  12. Effect of Ground Surface Reflectance on LiDAR Waveforms, Height Metrics and Biomass Estimation

    Science.gov (United States)

    Cook, B. D.; Rosette, J.; North, P. R.; Rubio, J.; Suárez, J.

    2010-12-01

    Forest attributes such as aboveground woody biomass are commonly derived from LiDAR waveforms using empirical relationships with relative height metrics, i.e., percentiles of returned energy relative to the ground elevation. However, LiDAR waveforms and height metrics are strongly influenced by the reflectance properties of vegetation, soils, and litter at or near the ground surface, adding a level of uncertainty to biomass estimates. To estimate this range of uncertainty, we used FLIGHT, a ray tracing radiative transfer model that simulates single and multiple scattering, to simulate the effect of realistic ground cover types in a mixed, intermediate-aged forest near Howland, Maine, USA. Simulated cover types included sphagnum moss, lichen, leaf litter, bare soil, and snow, which were evaluated for forest canopy cover ranging from 27 to 98%. We discuss multiple scattering in feature waveforms (i.e., reflected energy above the ground peak) and attempts to reduce biomass uncertainty by excluding potentially confounding ground returns.

  13. Automated Extraction of 3D Trees from Mobile LiDAR Point Clouds

    Science.gov (United States)

    Yu, Y.; Li, J.; Guan, H.; Zai, D.; Wang, C.

    2014-06-01

    This paper presents an automated algorithm for extracting 3D trees directly from 3D mobile light detection and ranging (LiDAR) data. To reduce both computational and spatial complexities, ground points are first filtered out from a raw 3D point cloud via blockbased elevation filtering. Off-ground points are then grouped into clusters representing individual objects through Euclidean distance clustering and voxel-based normalized cut segmentation. Finally, a model-driven method is proposed to achieve the extraction of 3D trees based on a pairwise 3D shape descriptor. The proposed algorithm is tested using a set of mobile LiDAR point clouds acquired by a RIEGL VMX-450 system. The results demonstrate the feasibility and effectiveness of the proposed algorithm.

  14. Clustering and visualization of non-classified points from LiDAR data for helicopter navigation

    Science.gov (United States)

    Eisenkeil, Ferdinand; Schafhitzel, Tobias; Kühne, Uwe; Deussen, Oliver

    2014-06-01

    In this paper we propose a dynamic DBSCAN-based method to cluster and visualize unclassified and potential dangerous obstacles in data sets recorded by a LiDAR sensor. The sensor delivers data sets in a short time interval, so a spatial superposition of multiple data sets is created. We use this superposition to create clusters incrementally. Knowledge about the position and size of each cluster is used to fuse clusters and the stabilization of clusters within multiple time frames. Cluster stability is a key feature to provide a smooth and un-distracting visualization for the pilot. Only a few lines are indicating the position of threatening unclassified points, where a hazardous situation for the helicopter could happen, if it comes too close. Clustering and visualization form a part of an entire synthetic vision processing chain, in which the LiDAR points support the generation of a real-time synthetic view of the environment.

  15. Automatic segmentation of road overpasses and detection of mortar efflorescence using mobile LiDAR data

    Science.gov (United States)

    González-Jorge, H.; Puente, I.; Riveiro, B.; Martínez-Sánchez, J.; Arias, P.

    2013-12-01

    This manuscript presents a novel method to automatize the efflorescence detection process in road overpasses using the geometric and radiometric informations from mobile LiDAR data. The study is performed over three main groups of algorithms. First, a data reduction algorithm based on the point cloud normalization, radial and vegetation filters is implemented. A second group of segmentation and classification algorithms uses the incidence angle derived by the LiDAR sensors to separate overpasses from pavement data. Finally, an algorithm to classify efflorescence considering its reflectivity lower than the surrounding granite is developed. The experimental results demonstrate the effectiveness of the method, using field data from the New Bridge of Ourense (Spain).

  16. Characterization of Forest Ecosystems by combined Radiative Transfer Modeling for Imaging Spectrometer and LiDAR

    Science.gov (United States)

    Koetz, B.; Sun, G.; Morsdorf, F.; Rubio, J.; Kimes, D.; Ranson, J.

    2009-04-01

    This research was motivated by the increased information dimensionality provided by current Earth Observation systems measuring the complex and dynamic medium of the vegetated surface of the Earth. Advanced and reliable algorithms that fully exploit this enhanced Earth Observation information are needed to deliver consistent data sets of the Earth vegetation condition describing its spatial distribution and change over time. Spectral observation provided by imaging spectrometers and the waveform from large-footprint LiDAR are now available from space for forest ecosystem studies. The imaging spectrometer data contains information about the biochemical composition of the canopy foliage, and is widely used to estimate biophysical canopy parameters such as LAI and fractional cover. LiDAR responds to the vertical distribution of scatters and permits inferences about the plant structures required to supply water and mechanical support to those surfaces. Various canopy height indices derived from LiDAR waveform have been successfully used to infer forest above-ground biomass and the characterization of canopy structure. The structure parameters derived from LiDAR data can improve the accuracy and robustness of canopy parameter retrieval from imaging spectrometer by reducing uncertainties related to the canopy structure. The specific information content, inherent to the observations of imaging spectrometry and LIDAR, assesses thus different but complementary characteristics of the complex vegetation canopy. The combination of these two information dimensions offers a unique and reliable canopy characterization including information relevant to different aspects of the biochemical and biophysical properties and thus understanding of processes within forest ecosystems. A comprehensive canopy characterization of a forest ecosystem is derived from the combined remote sensing signal of imaging spectrometry and large footprint LIDAR. The inversion of two linked physically based Radiative Transfer Models (RTM) provided the platform for synergistically exploiting the specific and independent information dimensions obtained by the two earth observation systems. The proposed research relies on a radiative transfer model adapted to imaging spectrometer data (GeoSAIL) and a LiDAR waveform model based on the same 3D canopy structure. Both the GeoSAIL and LiDAR waveform models have already been employed and validated to retrieve forest properties from Imaging Spectrometer and LiDAR data separately. As these models are based on the same basic physical concept and share common input parameters an interface between these models can be established, which allows for the generation of a Look Up Table (LUT) consisting of the simulated signatures of the Imaging Spectrometer and LiDAR as a function of a common forest stand parameterization. In the presented approach, the specific information content inherent to the observations of the respective sensor was not only able to complement the canopy characterization, but also helped to solve the ill-posed problem of the RTM inversion. A comprehensive data set including EO and field data has been available for the validation of the proposed earth observation concept over a mixed hardwood and softwood forest part of the Northern Experimental Forest (NEF), Howland, Maine (45°15'N, 68°45'W). The Laser Vegetation Imaging Sensor (LVIS) acquired full waveform data over the site in the summer of 2003 as part of a NASA Terrestrial Ecology Program aircraft campaign. Further the Compact High Resolution Imaging Spectrometer (CHRIS) on the ESA platform Proba data acquired imaging spectrometer data in 2006-08. As reference data every tree in a 200m by 150m area was measured for its location, dbh, and species in 1990, and was re-measured in 2003-2004 and 2006. The field data has been complemented by hemispherical photographs characterizing the canopy structure as well as with field spectrometer measurements of the optical properties for relevant scatters and background. The presented approach provides robust estimates

  17. Advances in animal ecology from 3D-LiDAR ecosystem mapping.

    Science.gov (United States)

    Davies, Andrew B; Asner, Gregory P

    2014-12-01

    The advent and recent advances of Light Detection and Ranging (LiDAR) have enabled accurate measurement of 3D ecosystem structure. Here, we review insights gained through the application of LiDAR to animal ecology studies, revealing the fundamental importance of structure for animals. Structural heterogeneity is most conducive to increased animal richness and abundance, and increased complexity of vertical vegetation structure is more positively influential compared with traditionally measured canopy cover, which produces mixed results. However, different taxonomic groups interact with a variety of 3D canopy traits and some groups with 3D topography. To develop a better understanding of animal dynamics, future studies will benefit from considering 3D habitat effects in a wider variety of ecosystems and with more taxa. PMID:25457158

  18. A comparison of waveform processing algorithms for single-wavelength LiDAR bathymetry

    Science.gov (United States)

    Wang, Chisheng; Li, Qingquan; Liu, Yanxiong; Wu, Guofeng; Liu, Peng; Ding, Xiaoli

    2015-03-01

    Due to the low-cost and lightweight units, single-wavelength LiDAR bathymetric systems are an ideal option for shallow-water (LiDAR waveforms captured over land. A simulated dataset and an Optech Aquarius dataset were used to assess the algorithms, with the focus being on their capability of extracting the depth and the bottom response. The influences of a number of water and equipment parameters were also investigated by the use of a Monte Carlo method. The results showed that the RLD method had a superior performance in terms of a high detection rate and low errors in the retrieved depth and magnitude. The attenuation coefficient, noise level, water depth, and bottom reflectance had significant influences on the measurement error of the retrieved depth, while the effects of scan angle and water surface roughness were not so obvious.

  19. DArTFest – A Platform for High-Throughput Genome Profiling Within the Festuca – Lolium Complex.

    Czech Academy of Sciences Publication Activity Database

    Kopecký, David; Bartoš, Jan; Lukaszewski, A.J.; Baird, J. H.; ?ernoch, V.; Kölliker, R.; Sandve, S.R.; Rognli, O.A.; Blois, H.; Caig, V.; Doležel, Jaroslav; Kilian, A.

    Dordrecht : Springer, 2010 - (Huyghe, C.), s. 443-448 ISBN 978-90-481-8705-8 R&D Projects: GA MZe QH71267; GA ?R GP521/07/P479 Institutional research plan: CEZ:AV0Z50380511 Keywords : DArT * Fescue * Hybrids Subject RIV: EB - Genetics ; Molecular Biology www.springerlink.com/content/j776m4/#section=713733&page=1

  20. Estimating Volume, Biomass, and Carbon in Hedmark County, Norway Using a Profiling LiDAR

    Science.gov (United States)

    Nelson, Ross; Naesset, Erik; Gobakken, T.; Gregoire, T.; Stahl, G.

    2009-01-01

    A profiling airborne LiDAR is used to estimate the forest resources of Hedmark County, Norway, a 27390 square kilometer area in southeastern Norway on the Swedish border. One hundred five profiling flight lines totaling 9166 km were flown over the entire county; east-west. The lines, spaced 3 km apart north-south, duplicate the systematic pattern of the Norwegian Forest Inventory (NFI) ground plot arrangement, enabling the profiler to transit 1290 circular, 250 square meter fixed-area NFI ground plots while collecting the systematic LiDAR sample. Seven hundred sixty-three plots of the 1290 plots were overflown within 17.8 m of plot center. Laser measurements of canopy height and crown density are extracted along fixed-length, 17.8 m segments closest to the center of the ground plot and related to basal area, timber volume and above- and belowground dry biomass. Linear, nonstratified equations that estimate ground-measured total aboveground dry biomass report an R(sup 2) = 0.63, with an regression RMSE = 35.2 t/ha. Nonstratified model results for the other biomass components, volume, and basal area are similar, with R(sup 2) values for all models ranging from 0.58 (belowground biomass, RMSE = 8.6 t/ha) to 0.63. Consistently, the most useful single profiling LiDAR variable is quadratic mean canopy height, h (sup bar)(sub qa). Two-variable models typically include h (sup bar)(sub qa) or mean canopy height, h(sup bar)(sub a), with a canopy density or a canopy height standard deviation measure. Stratification by productivity class did not improve the nonstratified models, nor did stratification by pine/spruce/hardwood. County-wide profiling LiDAR estimates are reported, by land cover type, and compared to NFI estimates.

  1. Drainage Structure Datasets and Effects on LiDAR-Derived Surface Flow Modeling

    OpenAIRE

    Ruopu Li; Zhenghong Tang; Xu Li; Jessie Winter

    2013-01-01

    With extraordinary resolution and accuracy, Light Detection and Ranging (LiDAR)-derived digital elevation models (DEMs) have been increasingly used for watershed analyses and modeling by hydrologists, planners and engineers. Such high-accuracy DEMs have demonstrated their effectiveness in delineating watershed and drainage patterns at fine scales in low-relief terrains. However, these high-resolution datasets are usually only available as topographic DEMs rather than hydrologic DEMs, present...

  2. DARS2 mutations in mitochondrial leukoencephalopathy and multiple sclerosis

    OpenAIRE

    2010-01-01

    Abstract Background: Leukoencephalopathy with brain stem and spinal cord involvement and high brain lactate (LBSL) was first defined by characteristic MRI and spectroscopic findings. The clinical features include childhood or juvenile-onset slowly progressive ataxia, spasticity, and dorsal column dysfunction, occasionally accompanied by learning difficulties. Mutations in DARS2, encoding mitochondrial aspartyl-tRNA synthetase, were recently shown to cause LBSL. The signs and sympt...

  3. 3D turbulence measurements in inhomogeneous boundary layers with three wind LiDARs

    Science.gov (United States)

    Carbajo Fuertes, Fernando; Valerio Iungo, Giacomo; Porté-Agel, Fernando

    2014-05-01

    One of the most challenging tasks in atmospheric anemometry is obtaining reliable turbulence measurements of inhomogeneous boundary layers at heights or in locations where is not possible or convenient to install tower-based measurement systems, e.g. mountainous terrain, cities, wind farms, etc. Wind LiDARs are being extensively used for the measurement of averaged vertical wind profiles, but they can only successfully accomplish this task under the limiting conditions of flat terrain and horizontally homogeneous flow. Moreover, it has been shown that common scanning strategies introduce large systematic errors in turbulence measurements, regardless of the characteristics of the flow addressed. From the point of view of research, there exist a variety of techniques and scanning strategies to estimate different turbulence quantities but most of them rely in the combination of raw measurements with atmospheric models. Most of those models are only valid under the assumption of horizontal homogeneity. The limitations stated above can be overcome by a new triple LiDAR technique which uses simultaneous measurements from three intersecting Doppler wind LiDARs. It allows for the reconstruction of the three-dimensional velocity vector in time as well as local velocity gradients without the need of any turbulence model and with minimal assumptions [EGU2013-9670]. The triple LiDAR technique has been applied to the study of the flow over the campus of EPFL in Lausanne (Switzerland). The results show the potential of the technique for the measurement of turbulence in highly complex boundary layer flows. The technique is particularly useful for micrometeorology and wind engineering studies.

  4. New possibilities for damage prediction from tunnel subsidence using aerial LiDAR data

    OpenAIRE

    Laefer, Debra F.; Hinks, Tommy; Carr, Hamish

    2010-01-01

    Computation modelling has not been fully exploited for predicting building damage due to tunnel-induced subsidence, because of the expense and time required to create computational meshes for the vast quantity of buildings that may be impacted along a tunnel’s route. A possible circumvention of such a resource commitment lies in the exploitation of remote sensing data in the form of aerial laser scans (also know as Light Detection and Ranging – LiDAR). This paper presents work accomplish...

  5. Urban 3D GIS From LiDAR and digital aerial images

    Science.gov (United States)

    Zhou, Guoqing; Song, C.; Simmers, J.; Cheng, P.

    2004-05-01

    This paper presents a method, which integrates image knowledge and Light Detection And Ranging (LiDAR) point cloud data for urban digital terrain model (DTM) and digital building model (DBM) generation. The DBM is an Object-Oriented data structure, in which each building is considered as a building object, i.e., an entity of the building class. The attributes of each building include roof types, polygons of the roof surfaces, height, parameters describing the roof surfaces, and the LiDAR point array within the roof surfaces. Each polygon represents a roof surface of building. This type of data structure is flexible for adding other building attributes in future, such as texture information and wall information. Using image knowledge extracted, we developed a new method of interpolating LiDAR raw data into grid digital surface model (DSM) with considering the steep discontinuities of buildings. In this interpolation method, the LiDAR data points, which are located in the polygon of roof surfaces, first are determined, and then interpolation via planar equation is employed for grid DSM generation. The basic steps of our research are: (1) edge detection by digital image processing algorithms; (2) complete extraction of the building roof edges by digital image processing and human-computer interactive operation; (3) establishment of DBM; (4) generation of DTM by removing surface objects. Finally, we implement the above functions by MS VC++ programming. The outcome of urban 3D DSM, DTM and DBM is exported into urban database for urban 3D GIS.

  6. Step by step error assessment in braided river sediment budget using airborne LiDAR data

    Science.gov (United States)

    Lallias-Tacon, S.; Liébault, F.; Piégay, H.

    2014-06-01

    Sequential airborne LiDAR surveys were used to reconstruct the sediment budget of a 7-km-long braided river channel in southeastern France following a 14-year return period flood and to improve its accuracy step by step. Data processing involved (i) surface matching of the sequential point clouds, (ii) spatially distributed propagation of uncertainty based on surface conditions of the channel, and (iii) water depth subtraction from the digital elevation models based on water depths measured in the field. The respective influence of each processing step on sediment budget computation was systematically documented. This showed that surface matching and water depth subtraction both have a considerable effect on the net sediment budget. Although DEM of difference thresholding based on uncertainty analysis on absolute elevation values had a smaller effect on the sediment budget, this step is crucial for the production of a comprehensive map of channel deformations. A large independent data set of RTK-GPS checkpoints was used to control the quality of the LiDAR altimetry. The results showed that high density (7-9 points/m2) airborne LiDAR surveys can provide a very high level of detection of elevation changes on the exposed surfaces of the channel, with a 95% confidence interval level of detection between 19 and 30 cm. Change detection from LiDAR data revealed that 54% of the pre-flood active channel was reworked by the flood. The braided channel pattern was highly disturbed by the flood owing to the occurrence of several channel avulsions.

  7. Combining LiDAR and IKONOS data for eco-hydrological classification of an ombrotrophic peatland.

    Science.gov (United States)

    Anderson, K; Bennie, J J; Milton, E J; Hughes, P D M; Lindsay, R; Meade, R

    2010-01-01

    Remote sensing techniques have potential for peatland monitoring, but most previous work has focused on spectral approaches that often result in poor discrimination of cover types and neglect structural information. Peatlands contain structural "microtopes" (e.g., hummocks and hollows) which are linked to hydrology, biodiversity and carbon sequestration, and information on surface structure is thus a useful proxy for peatland condition. The objective of this work was to develop and test a new eco-hydrological mapping technique for ombrotrophic (rain-fed) peatlands using a combined spectral-structural remote sensing approach. The study site was Wedholme Flow, Cumbria, UK. Airborne light dectection and ranging (LiDAR) data were used with IKONOS data in a combined multispectral-structural approach for mapping peatland condition classes. LiDAR data were preprocessed so that spatial estimates of minimum and maximum land surface height, variance and semi-variance (from semi-variogram analysis) were extracted. These were assimilated alongside IKONOS data into a maximum likelihood classification procedure, and thematic outputs were compared. Ecological survey data were used to validate the results. Considerable improvements in thematic separation of peatland classes were achieved when spatially-distributed measurements of LiDAR variance or semi-variance were included. Specifically, the classification accuracy improved from 71.8% (IKONOS data only) to 88.0% when a LiDAR semi-variance product was used. Of note was the improved delineation of management classes (including Eriophorum bog, active raised bog and degraded raised bog). The application of a combined textural-optical approach can improve land cover mapping in areas where reliance on purely spectral discrimination approaches would otherwise result in considerable thematic uncertainty. PMID:20048314

  8. Mapping and Monitoring Delmarva Fox Squirrel Habitat Using an Airborne LiDAR Profiler

    Science.gov (United States)

    Nelson, Ross; Ratnaswamy, Mary; Keller, Cherry

    2004-01-01

    Twenty five hundred thirty nine kilometers of airborne laser profiling and videography data were acquired over the state of Delaware during the summer of 2000. The laser ranging measurements and video from approximately one-half of that data set (1304 km) were analyzed to identify and locate forested sites that might potentially support populations of Delmarva fox squirrel (DFS, Sciurus niger cinereus). The DFS is an endangered species previously endemic to tall, dense, mature forests with open understories on the Eastern Shore of the Chesapeake Bay. The airborne LiDAR employed in this study can measure forest canopy height and canopy closure, but cannot measure or infer understory canopy conditions. Hence the LiDAR must be viewed as a tool to map potential, not actual, habitat. Fifty-three potentially suitable DFS sites were identified in the 1304 km of flight transect data. Each of the 53 sites met the following criteria according to the LiDAR and video record: (1 ) at least 120m of contiguous forest; (2) an average canopy height greater than 20m; (3) an average canopy closure of >80%; and (4) no roofs, impervious surface (e.g., asphalt, concrete), and/or open water anywhere along the 120m length of the laser segment. Thirty-two of the 53 sites were visited on the ground and measurements taken for a DFS habitat suitability model. Seventy eight percent of the sites (25 of 32) were judged by the model to be suited to supporting a DFS population. Twenty-eight of the 32 sites visited in the field were in forest cover types (hardwood, mixed wood, conifer, wetlands) according to a land cover GIS map. Of these, 23 (82%) were suited to support DFS. The remaining 4 sites were located in nonforest cover types - agricultural or residential areas. Two of the four, or 50% were suited to the DFS. All of the LiDAR flight data, 2539 km, were analyzed to

  9. Extracting More Data from LiDAR in Forested Areas by Analyzing Waveform Shape

    OpenAIRE

    Peter Beets; Christopher Parrish; Thomas Adams

    2012-01-01

    Light Detection And Ranging (LiDAR) in forested areas is used for constructing Digital Terrain Models (DTMs), estimating biomass carbon and timber volume and estimating foliage distribution as an indicator of tree growth and health. All of these purposes are hindered by the inability to distinguish the source of returns as foliage, stems, understorey and the ground except by their relative positions. The ability to separate these returns would improve all analyses significantly. Furthermore, ...

  10. Strategies for minimizing sample size for use in airborne LiDAR-based forest inventory

    Science.gov (United States)

    Junttila, Virpi; Finley, Andrew O.; Bradford, John B.; Kauranne, Tuomo

    2013-01-01

    Recently airborne Light Detection And Ranging (LiDAR) has emerged as a highly accurate remote sensing modality to be used in operational scale forest inventories. Inventories conducted with the help of LiDAR are most often model-based, i.e. they use variables derived from LiDAR point clouds as the predictive variables that are to be calibrated using field plots. The measurement of the necessary field plots is a time-consuming and statistically sensitive process. Because of this, current practice often presumes hundreds of plots to be collected. But since these plots are only used to calibrate regression models, it should be possible to minimize the number of plots needed by carefully selecting the plots to be measured. In the current study, we compare several systematic and random methods for calibration plot selection, with the specific aim that they be used in LiDAR based regression models for forest parameters, especially above-ground biomass. The primary criteria compared are based on both spatial representativity as well as on their coverage of the variability of the forest features measured. In the former case, it is important also to take into account spatial auto-correlation between the plots. The results indicate that choosing the plots in a way that ensures ample coverage of both spatial and feature space variability improves the performance of the corresponding models, and that adequate coverage of the variability in the feature space is the most important condition that should be met by the set of plots collected.

  11. A Comparative Study between Frequency-Modulated Continous Wave LADAR and Linear LiDAR

    Science.gov (United States)

    Massaro, R. D.; Anderson, J. E.; Nelson, J. D.; Edwards, J. D.

    2014-11-01

    Topographic Light Detection and Ranging (LiDAR) technology has advanced greatly in the past decade. Pulse repetition rates of terrestrial and airborne systems havemultiplied thus vastly increasing data acquisition rates. Geiger-mode and FLASH LiDAR have also become far more mature technologies. However, a new and relatively unknown technology is maturing rapidly: Frequency-Modulated Continuous Wave Laser Detection and Ranging (FMCW-LADAR). Possessing attributes more akin to modern radar systems, FMCWLADAR has the ability to more finely resolve objects separated by very small ranges. For tactical military applications (as described here), this can be a real advantage over single frequency, direct-detect systems. In fact, FMCW-LADAR can range resolve objects at 10-7 to 10-6 meter scales. FMCW-LADAR can also detect objects at greater range with less power. In this study, a FMCWLADAR instrument and traditional LiDAR instrument are compared. The co-located terrestrial scanning instruments were set up to perform simultaneous 3-D measurements of the given scene. Several targets were placed in the scene to expose the difference in the range resolution capabilities of the two instruments. The scans were performed at or nearly the same horizontal and vertical angular resolutions. It is demonstrated that the FMCW-LADAR surpasses the perfomance of the linear mode LiDAR scanner in terms of range resolution. Some results showing the maximum range acquisition are discussed but this was not studied in detail as the scanners' laser powers differed by a small amount. Applications and implications of this technology are also discussed.

  12. Biology and management of fish stocks in Bahir Dar Gulf, Lake Tana, Ethiopia.

    OpenAIRE

    Wudneh, T.

    1998-01-01

    The biology of the fish stocks of the major species in the Bahir Dar Gulf of Lake Tana, the largest lake in Ethiopia, has been studied based on data collected during August 1990 to September 1993. The distribution, reproduction patterns, growth and mortality dynamics and gillnet selectivity of these stocks are described.The major fish categories, Barbus spp., Clarias gariepinus, and Oreochromis niloticus contribute equally to the catches. O. niloticus is most abundant in the shallow littoral ...

  13. Area-Based Mapping of Defoliation of Scots Pine Stands Using Airborne Scanning LiDAR

    OpenAIRE

    Hannu Hyyppä; Wulder, Michael A.; Juha Hyyppä; Ville Kankare; Markus Holopainen; Mikko Vastaranta; Päivi Lyytikäinen-Saarenmaa; Tuula Kantola

    2013-01-01

    The mapping of changes in the distribution of insect-caused forest damage remains an important forest monitoring application and challenge. Efficient and accurate methods are required for mapping and monitoring changes in insect defoliation to inform forest management and reporting activities. In this research, we develop and evaluate a LiDAR-driven (Light Detection And Ranging) approach for mapping defoliation caused by the Common pine sawfly (Diprion pini L.). Our method requires plot-level...

  14. LiDAR mapping of tidal marshes for ecogeomorphological modelling in the TIDE project

    OpenAIRE

    Mason, David Cecil; Marani, M.; Belluco, E.; Feola, A.; Ferrari, S.; Katzenbeisser, R.; Lohani, B.; Menenti, M.; Paterson, D. M.; Scott, T. R.; Vardy, S.; Wang, C.; Wang, H-j

    2005-01-01

    The European research project TIDE (Tidal Inlets Dynamics and Environment) is developing and validating coupled models describing the morphological, biological and ecological evolution of tidal environments. The interactions between the physical and biological processes occurring in these regions requires that the system be studied as a whole rather than as separate parts. Extensive use of remote sensing including LiDAR is being made to provide validation data for the modelling. This pape...

  15. A Comparison of Two Open Source LiDAR Surface Classification Algorithms

    Directory of Open Access Journals (Sweden)

    Danny G Marks

    2011-03-01

    Full Text Available With the progression of LiDAR (Light Detection and Ranging towards a mainstream resource management tool, it has become necessary to understand how best to process and analyze the data. While most ground surface identification algorithms remain proprietary and have high purchase costs; a few are openly available, free to use, and are supported by published results. Two of the latter are the multiscale curvature classification and the Boise Center Aerospace Laboratory LiDAR (BCAL algorithms. This study investigated the accuracy of these two algorithms (and a combination of the two to create a digital terrain model from a raw LiDAR point cloud in a semi-arid landscape. Accuracy of each algorithm was assessed via comparison with >7,000 high precision survey points stratified across six different cover types. The overall performance of both algorithms differed by only 2%; however, within specific cover types significant differences were observed in accuracy. The results highlight the accuracy of both algorithms across a variety of vegetation types, and ultimately suggest specific scenarios where one approach may outperform the other. Each algorithm produced similar results except in the ceanothus and conifer cover types where BCAL produced lower errors.

  16. High-Density LiDAR Mapping of the Ancient City of Mayapán

    Directory of Open Access Journals (Sweden)

    Timothy Hare

    2014-09-01

    Full Text Available A 2013 survey of a 40 square kilometer area surrounding Mayapán, Yucatan, Mexico used high-density LiDAR data to map prehispanic architecture and related natural features. Most of the area is covered by low canopy dense forest vegetation over karstic hilly terrain that impedes full coverage archaeological survey. We used LiDAR at 40 laser points per square meter to generate a bare earth digital elevation model (DEM. Results were evaluated with comparisons to previously mapped areas and with traditional archaeological survey methods for 38 settlement clusters outside of the city wall. Ground checking employed full coverage survey of selected 500 m grid squares, as well as documentation of the chronology and detail of new public and domestic settlement features and cenotes. Results identify the full extent of continued, contemporary Postclassic settlement (A.D. 1150–1450 outside of the city wall to at least 500 meters to the east, north, and west. New data also reveal an extensive modified landscape of terraformed residential hills, rejolladas, and dense settlement dating from Preclassic through Classic Periods. The LiDAR data also allow for the identification of rooms, benches, and stone property walls and lanes within the city.

  17. Accuracy and Precision of Terrestrial LiDAR for Ground Deformation Monitoring

    Science.gov (United States)

    Aryal, A.; Brooks, B. A.; Foster, J. H.

    2007-12-01

    With controlled experiments and multiple occupations of a field site at Waimea Bay, Oahu, we are assessing the accuracy and precision for geodetic applications of the Optech ILRIS 3-D, a near-infrared (1.2 micron wavelength) Terrestrial-LiDAR (T-LiDAR) system. For the controlled experiments, we have built a stable table with a grid of peg holes and estimated static offsets and translations of a geodetic target (a Leica GPS antenna and radome). We scan the radome from variable distances (50 -1000 m) and with variable spot spacing. We use the 3D point cloud data to model the phase center of the radome by fitting all data points to a spherical model in a local co-ordinate frame. Preliminary results show that from over 1400 individual scans with spot-spacing ranging from 2 mm to 20 mm and over distances of 100-180 meters, the phase center of the radome derived from T-LiDAR measurements and solid modeling is achieved with better than 2-4 mm standard deviation. At the field site we have conducted more than 30 scans over a period of 3 months of an area with dimensions ranging from ~300 - 1000 m. While the beach face changes significantly during this time period, the area behind the beach does not allowing us to analyze the multiple natural and human-made targets there for their stability at a variety of distances and weather conditions.

  18. Characterisation of the surface morphology of an alpine alluvial fan using airborne LiDAR

    Directory of Open Access Journals (Sweden)

    M. Cavalli

    2008-04-01

    Full Text Available Alluvial fans of alpine torrents are both natural deposition areas for sediment discharged by floods and debris flows, and preferred sites for agriculture and settlements. Hazard assessment on alluvial fans depends on proper identification of flow processes and their potential intensity. This study used LiDAR data to examine the morphology of the alluvial fan of a small alpine stream (Moscardo Torrent, Eastern Italian Alps. A high-resolution DTM from LiDAR data was used to calculate a shaded relief map, plan curvature and an index of topographic roughness based on the standard deviation of elevation within a moving window. The surface complexity of the alluvial fan, also influenced by human activities, clearly arose from the analysis. The surface roughness, defined here as the local topography variability, is compared with a previous classification of the fan surface based on field surveys. The results demonstrate that topographic analysis of ground based LiDAR DTM can be a useful tool to objectively investigate fan morphology and hence alluvial fan hazard assessment.

  19. LiDAR scan and smart piezo layer combined damage detection

    Science.gov (United States)

    Chen, Shenen; Chung, Howard; Park, Youngjin

    2013-04-01

    The motivation of this study is to determine a technique to completely describe the damage state of large deformed structures commonly found during forensic investigations. The combination of Laser Detecting and Ranging (LiDAR) and Piezoelectric (PZT) Sensing Technologies for damage quantification is suggested to generate the full-field description of large deformation of a plate. The test subject is a 16 inch by 16 inch aluminum plate subjected to different damage scenarios. LiDAR is a static scanning laser that provides a 3-dimensional picture of the object. Smart Layer is a commercial PZT actuator/sensor network system that generates stress waves for internal damage evaluation. Both techniques were applied to the test plate after damages are introduced. In order to effectively analyze the results, the images for each test were superimposed. Frequencies that depicted the best interpretation of damage in the direct path images were superimposed with the 3-dimensional LiDAR images. Four damage scenarios were imposed on an aluminum plate including saw cuts at different depths using an electric saw. The final damage is a severe bending of the plate. The bending of the specimen produced an image that located the most severe damage directly under the left hand portion and directly above the right hand portion of the bend.

  20. Geodetic imaging with airborne LiDAR: the Earth's surface revealed.

    Science.gov (United States)

    Glennie, C L; Carter, W E; Shrestha, R L; Dietrich, W E

    2013-08-01

    The past decade has seen an explosive increase in the number of peer reviewed papers reporting new scientific findings in geomorphology (including fans, channels, floodplains and landscape evolution), geologic mapping, tectonics and faulting, coastal processes, lava flows, hydrology (especially snow and runoff routing), glaciers and geo-archaeology. A common genesis of such findings is often newly available decimeter resolution 'bare Earth' geodetic images, derived from airborne laser swath mapping, a.k.a. airborne LiDAR, observations. In this paper we trace nearly a half century of advances in geodetic science made possible by space age technology, such as the invention of short-pulse-length high-pulse-rate lasers, solid state inertial measurement units, chip-based high speed electronics and the GPS satellite navigation system, that today make it possible to map hundreds of square kilometers of terrain in hours, even in areas covered with dense vegetation or shallow water. To illustrate the impact of the LiDAR observations we present examples of geodetic images that are not only stunning to the eye, but help researchers to develop quantitative models explaining how terrain evolved to its present form, and how it will likely change with time. Airborne LiDAR technology continues to develop quickly, promising ever more scientific discoveries in the years ahead. PMID:23828665

  1. Geodetic imaging with airborne LiDAR: the Earth's surface revealed

    International Nuclear Information System (INIS)

    The past decade has seen an explosive increase in the number of peer reviewed papers reporting new scientific findings in geomorphology (including fans, channels, floodplains and landscape evolution), geologic mapping, tectonics and faulting, coastal processes, lava flows, hydrology (especially snow and runoff routing), glaciers and geo-archaeology. A common genesis of such findings is often newly available decimeter resolution ‘bare Earth’ geodetic images, derived from airborne laser swath mapping, a.k.a. airborne LiDAR, observations. In this paper we trace nearly a half century of advances in geodetic science made possible by space age technology, such as the invention of short-pulse-length high-pulse-rate lasers, solid state inertial measurement units, chip-based high speed electronics and the GPS satellite navigation system, that today make it possible to map hundreds of square kilometers of terrain in hours, even in areas covered with dense vegetation or shallow water. To illustrate the impact of the LiDAR observations we present examples of geodetic images that are not only stunning to the eye, but help researchers to develop quantitative models explaining how terrain evolved to its present form, and how it will likely change with time. Airborne LiDAR technology continues to develop quickly, promising ever more scientific discoveries in the years ahead. (review article)

  2. Phylogenetic Relationships between Four Salix L. Species Based on DArT Markers

    Directory of Open Access Journals (Sweden)

    Jerzy A. Przyborowski

    2013-12-01

    Full Text Available The objectives of this study were to evaluate the usefulness of DArT markers in genotypic identification of willow species and describe genetic relationships between four willow species: Salix viminalis, S. purpurea, S. alba and S. triandra. The experimental plant material comprised 53 willow genotypes of these four species, which are popularly grown in Poland. DArT markers seem to identify Salix species with a high degree of accuracy. As a result, the examined species were divided into four distinct groups which corresponded to the four analyzed species. In our study, we observed that S. triandra was very different genetically from the other species, including S. alba which is generally classified into the same subgenus of Salix. The above corroborates the findings of other authors who relied on molecular methods to reveal that the classification of S. triandra to the subgenus Salix was erroneous. The Principal Coordinate Analysis (PCoA and the neighbor-joining dendrogram also confirmed the clear division of the studied willow genotypes into four clusters corresponding to individual species. This confirmed the usefulness of DArT markers in taxonomic analyses and identification of willow species.

  3. Algorithm for Extracting Digital Terrain Models under Forest Canopy from Airborne LiDAR Data

    Directory of Open Access Journals (Sweden)

    Almasi S. Maguya

    2014-07-01

    Full Text Available Extracting digital elevationmodels (DTMs from LiDAR data under forest canopy is a challenging task. This is because the forest canopy tends to block a portion of the LiDAR pulses from reaching the ground, hence introducing gaps in the data. This paper presents an algorithm for DTM extraction from LiDAR data under forest canopy. The algorithm copes with the challenge of low data density by generating a series of coarse DTMs by using the few ground points available and using trend surfaces to interpolate missing elevation values in the vicinity of the available points. This process generates a cloud of ground points from which the final DTM is generated. The algorithm has been compared to two other algorithms proposed in the literature in three different test sites with varying degrees of difficulty. Results show that the algorithm presented in this paper is more tolerant to low data density compared to the other two algorithms. The results further show that with decreasing point density, the differences between the three algorithms dramatically increased from about 0.5m to over 10m.

  4. Motion Field Estimation for a Dynamic Scene Using a 3D LiDAR

    Science.gov (United States)

    Li, Qingquan; Zhang, Liang; Mao, Qingzhou; Zou, Qin; Zhang, Pin; Feng, Shaojun; Ochieng, Washington

    2014-01-01

    This paper proposes a novel motion field estimation method based on a 3D light detection and ranging (LiDAR) sensor for motion sensing for intelligent driverless vehicles and active collision avoidance systems. Unlike multiple target tracking methods, which estimate the motion state of detected targets, such as cars and pedestrians, motion field estimation regards the whole scene as a motion field in which each little element has its own motion state. Compared to multiple target tracking, segmentation errors and data association errors have much less significance in motion field estimation, making it more accurate and robust. This paper presents an intact 3D LiDAR-based motion field estimation method, including pre-processing, a theoretical framework for the motion field estimation problem and practical solutions. The 3D LiDAR measurements are first projected to small-scale polar grids, and then, after data association and Kalman filtering, the motion state of every moving grid is estimated. To reduce computing time, a fast data association algorithm is proposed. Furthermore, considering the spatial correlation of motion among neighboring grids, a novel spatial-smoothing algorithm is also presented to optimize the motion field. The experimental results using several data sets captured in different cities indicate that the proposed motion field estimation is able to run in real-time and performs robustly and effectively. PMID:25207868

  5. Motion Field Estimation for a Dynamic Scene Using a 3D LiDAR

    Directory of Open Access Journals (Sweden)

    Qingquan Li

    2014-09-01

    Full Text Available This paper proposes a novel motion field estimation method based on a 3D light detection and ranging (LiDAR sensor for motion sensing for intelligent driverless vehicles and active collision avoidance systems. Unlike multiple target tracking methods, which estimate the motion state of detected targets, such as cars and pedestrians, motion field estimation regards the whole scene as a motion field in which each little element has its own motion state. Compared to multiple target tracking, segmentation errors and data association errors have much less significance in motion field estimation, making it more accurate and robust. This paper presents an intact 3D LiDAR-based motion field estimation method, including pre-processing, a theoretical framework for the motion field estimation problem and practical solutions. The 3D LiDAR measurements are first projected to small-scale polar grids, and then, after data association and Kalman filtering, the motion state of every moving grid is estimated. To reduce computing time, a fast data association algorithm is proposed. Furthermore, considering the spatial correlation of motion among neighboring grids, a novel spatial-smoothing algorithm is also presented to optimize the motion field. The experimental results using several data sets captured in different cities indicate that the proposed motion field estimation is able to run in real-time and performs robustly and effectively.

  6. LiDAR point cloud comparison: evaluation of denoising techniques using 3D moving windows

    Science.gov (United States)

    Abellán, Antonio; Carrea, Dario; Jaboyedoff, Michel; Royan, Manuel Jesus

    2013-04-01

    Laser scanner techniques (also referred to as LiDAR) have recently allowed the acquisition of high accuracy and high resolution 3D geometry of the terrain. A large set of geomorphological applications currently deal with precise recognition of changes on different environments as riverside erosion, rock cliff deformation, landslide evolution, etc., being the development of new change detection techniques a current challenge. When dealing with small changes on terrain surface quantification, e.g. slow erosion rates and small scale slope deformation, real change could be masked due to instrumental noise (mm to cm order of magnitude), being of capital importance the application of filtering techniques in order to remove Gaussian noise associated to LiDAR data acquisition. We present an evaluation on the application of different linear and nonlinear adaptive spatial filtering techniques (e.g. min, max, mean, median, Wiener..) to a multi-temporal point cloud comparison. Both synthetic datasets and real case study of rock cliff deformation were used. In order to benefit from data redundancy, we considerably reduced results uncertainty by using 3D moving windows along the space and time. Different windows size were tested, both using uniform and non-uniform boxes. The implementation of our findings on new generation ground-based permanent LiDAR devices will lead to a better process understanding of small or relatively slow changes that may act as key actors of future slope evolution, as the early detection of millimetric cliff deformation before million cubic failures.

  7. ASTER GDEM validation using LiDAR data over coastal regions of Greenland

    DEFF Research Database (Denmark)

    Hvidegaard, Sine Munk; SØrensen, Louise Sandberg

    2011-01-01

    Elevation data from airborne Light Detection and Ranging (LiDAR) campaigns are used in an attempt to evaluate the accuracy of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) global digital elevation model (GDEM) in Greenland. The LiDAR elevation data set is characterized by a high spatial resolution of about 1 m and elevation accuracy of 20–30 cm root mean square error (RMSE). The LiDAR data sets used were acquired during ice-monitoring campaigns carried out from 2003 to 2008. The study areas include ice-free regions, local ice caps and the ice sheet margin. A linear error of 15–65 m was derived, which is far greater than the 20-m product specification. This estimation is biased by both the seasonal and the climatic changes in local ice caps because the ASTER GDEM was computed from imagery acquired in the period 2000–2009. High sloping areas along the coastal regions of Greenland and the effect of the number of scenes used to generate the ASTER GDEM as well as relief are associatedwith the GDEM accuracy.

  8. Genetic Structure, Linkage Disequilibrium and Signature of Selection in Sorghum: Lessons from Physically Anchored DArT Markers

    OpenAIRE

    Bouchet, Sophie; Pot, David; Deu, Monique; Rami, Jean-franc?ois; Billot, Claire; Perrier, Xavier; Rivallan, Ronan; Gardes, Lae?titia; Xia, Ling; Wenzl, Peter; Kilian, Andrzej; Glaszmann, Jean-christophe

    2012-01-01

    Population structure, extent of linkage disequilibrium (LD) as well as signatures of selection were investigated in sorghum using a core sample representative of worldwide diversity. A total of 177 accessions were genotyped with 1122 informative physically anchored DArT markers. The properties of DArTs to describe sorghum genetic structure were compared to those of SSRs and of previously published RFLP markers. Model-based (STRUCTURE software) and Neighbor-Joining diversity analyses led to th...

  9. Above-Ground Biomass and Biomass Components Estimation Using LiDAR Data in a Coniferous Forest

    OpenAIRE

    Qisheng He; Erxue Chen; Ru An; Yong Li

    2013-01-01

    This study aims to estimate forest above-ground biomass and biomass components in a stand of Picea crassifolia (a coniferous tree) located on Qilian Mountain, western China via low density small-footprint airborne LiDAR data. LiDAR points were first classified into ground points and vegetation points. After, vegetation statistics, including height quantiles, mean height, and fractional cover were calculated. Stepwise multiple regression models were used to develop equations that relate the ve...

  10. Estimation of biomass and volume of shrub vegetation using LiDAR and spectral data in a Mediterranean environment

    OpenAIRE

    Estornell Cremades, Javier; Ruiz Ferna?ndez, Luis A?ngel; Vela?zquez Marti?, Borja; Hermosilla, T.

    2012-01-01

    Several studies have addressed the biomass and volume of trees using Airborne Light Detection and Ranging (LiDAR) data. However, little research has been conducted into shrub vegetation, which covers a high percentage of Mediterranean forest. We used LiDAR data and an airborne image to estimate biomass and volume of shrub vegetation. Field data were collected in 29 square plots of 100 m2. In each plot, the percentage of the surface covered was measured in the field. Shrub veget...

  11. Object-Based Integration of Photogrammetric and LiDAR Data for Automated Generation of Complex Polyhedral Building Models

    OpenAIRE

    Ayman Habib; Changjae Kim

    2009-01-01

    This research is concerned with a methodology for automated generation of polyhedral building models for complex structures, whose rooftops are bounded by straight lines. The process starts by utilizing LiDAR data for building hypothesis generation and derivation of individual planar patches constituting building rooftops. Initial boundaries of these patches are then refined through the integration of LiDAR and photogrammetric data and hierarchical processing of the planar patches. Building m...

  12. Semi-Supervised Methods to Identify Individual Crowns of Lowland Tropical Canopy Species Using Imaging Spectroscopy and LiDAR

    OpenAIRE

    Asner, Gregory P.; Jean-Baptiste Féret

    2012-01-01

    Our objective is to identify and map individuals of nine tree species in a Hawaiian lowland tropical forest by comparing the performance of a variety of semi-supervised classifiers. A method was adapted to process hyperspectral imagery, LiDAR intensity variables, and LiDAR-derived canopy height and use them to assess the identification accuracy. We found that semi-supervised Support Vector Machine classification using tensor summation kernel was superior to supervised classification, with dem...

  13. A method for parameterising roughness and topographic sub-grid scale effects in hydraulic modelling from LiDAR data

    OpenAIRE

    Casas, A.; Lane, S. N.; Yu, D.; Benito, G.

    2010-01-01

    High resolution airborne laser data provide new ways to explore the role of topographic complexity in hydraulic modelling parameterisation, taking into account the scale-dependency between roughness and topography. In this paper, a complex topography from LiDAR is processed using a spatially and temporally distributed method at a fine resolution. The surface topographic parameterisation considers the sub-grid LiDAR data points above and below a reference DEM, hereafter named as topographic co...

  14. Intensity normalization and automatic gain control correction of airborne LiDAR data for classifying a rangeland ecosystem

    Science.gov (United States)

    Shrestha, R.; Glenn, N. F.; Spaete, L.; Mitchell, J.

    2011-12-01

    Airborne LiDAR not only records elevation but also the intensity, or the amplitude, of the returning light beam. LiDAR intensity information can be useful for many applications, including landcover classification. Intensity is directly associated with the reflectance of the target surface and can be influenced by factors such as flying altitude and sensor settings. LiDAR intensity data must be calibrated before use and this is especially important for multi-temporal studies where differing flight conditions can cause more variations. Some sensors such as the Leica ALS50 Phase II also records automatic gain control (AGC), which controls the gain of the LiDAR signal, allowing information from low-reflectance surfaces. We demonstrate a post-processing method for calibrating intensity using airborne LiDAR data collected over a sage-steppe ecosystem in southeastern Idaho, USA. Range normalization with respect to the sensor-to-object distance is performed by using smoothed best estimated trajectory information collected at an interval of every second. Optimal parameters for calibrating AGC data are determined by collecting spectral reference data at the time of overflights, in test areas with homogenous backscatter properties. Intensity calibration results are compared with vendor corrected intensity data, and used to perform landcover classification using the Random Forests method. We also test this intensity calibration approach using a separate multi-temporal LiDAR data set collected by the same sensor.

  15. ¿El terrorismo global es amorfo o polimorfo?

    Directory of Open Access Journals (Sweden)

    Fernando Reinares

    2009-01-01

    Full Text Available La urdimbre del terrorismo global incluye, siete años después de los atentados del 11 de septiembre, tanto a una al–Qaeda reconstituida y a las extensiones territoriales que ha conseguido establecer, como al heterogéneo conjunto de grupos y organizaciones afines a la misma, al igual que a células locales independientes e informales constituidas de manera espontánea. Sería un error tomar esta última parte por el todo y afirmar que el terrorismo global es un fenómeno amorfo, cuando en realidad es polimorfo. Los riesgos y amenazas que el terrorismo global plantea para un determinado país o región del mundo dependen precisamente del modo en que se combinan sus distintos componentes. Para las sociedades occidentales, esos riesgos y amenazas no son ahora menores, aunque sí más complejos. Los atentados del 11 de marzo en Madrid constituyeron un ejemplo.

  16. Rigorous analysis of some simple adaptive ES

    OpenAIRE

    Auger, Anne; Le Bris, Claude; Schoenauer, Marc

    2003-01-01

    Based on the theory of non-negative supermartingales, convergence results are proven for adaptive (1,)-ES with Gaussian mutations, and geometrical convergence rates are derived. In the d-dimensional case (d > 1), the algorithm studied here uses a different step-size update in each direction. However, the critical value for the step-size, and the resulting convergence rate do not depend on the dimension. Those results are discussed with respect to previous works. Thorough numerical investigati...

  17. Financial sustainability in municipal solid waste management – Costs and revenues in Bahir Dar, Ethiopia

    Energy Technology Data Exchange (ETDEWEB)

    Lohri, Christian Riuji, E-mail: christian.lohri@eawag.ch; Camenzind, Ephraim Joseph, E-mail: ephraimcamenzind@hotmail.com; Zurbrügg, Christian, E-mail: christian.zurbruegg@eawag.ch

    2014-02-15

    Highlights: • Cost-revenue analysis over 2 years revealed insufficient cost-recovery. • Expenses for motorized secondary collection increased by 82% over two years. • Low fee collection rate and reliance on only one revenue stream are problematic. • Different options for cost reduction and enhanced revenue streams are recommended. • Good public–private alliance is crucial to plan and implement improvement measures. - Abstract: Providing good solid waste management (SWM) services while also ensuring financial sustainability of the system continues to be a major challenge in cities of developing countries. Bahir Dar in northwestern Ethiopia outsourced municipal waste services to a private waste company in 2008. While this institutional change has led to substantial improvement in the cleanliness of the city, its financial sustainability remains unclear. Is the private company able to generate sufficient revenues from their activities to offset the costs and generate some profit? This paper presents a cost-revenue analysis, based on data from July 2009 to June 2011. The analysis reveals that overall costs in Bahir Dar’s SWM system increased significantly during this period, mainly due to rising costs related to waste transportation. On the other hand, there is only one major revenue stream in place: the waste collection fee from households, commercial enterprises and institutions. As the efficiency of fee collection from households is only around 50%, the total amount of revenues are not sufficient to cover the running costs. This results in a substantial yearly deficit. The results of the research therefore show that a more detailed cost structure and cost-revenue analysis of this waste management service is important with appropriate measures, either by the privates sector itself or with the support of the local authorities, in order to enhance cost efficiency and balance the cost-revenues towards cost recovery. Delays in mitigating the evident financial deficit could else endanger the public-private partnership (PPP) and lead to failure of this setup in the medium to long term, thus also endangering the now existing improved and currently reliable service. We present four options on how financial sustainability of the SWM system in Bahir Dar might be enhanced: (i) improved fee collection efficiency by linking the fees of solid waste collection to water supply; (ii) increasing the value chain by sales of organic waste recycling products; (iii) diversifying revenue streams and financing mechanisms (polluter-pays-, cross-subsidy- and business-principles); and (iv) cost reduction and improved cost-effectiveness. We argue that in a PPP setup such as in Bahir Dar, a strong alliance between the municipality and private enterprise is important so that appropriate solutions for improved financial sustainability of a SWM system can be sought and implemented.

  18. Multiple-LiDAR measurements of wind turbine wakes: effect of the atmospheric stability

    Science.gov (United States)

    Valerio Iungo, Giacomo; Porté-Agel, Fernando

    2013-04-01

    Aerodynamic design and optimization of a wind farm layout are mainly based on the evaluation of wind turbine wake recovery by moving downstream, and on the characterization of wake interactions within a wind farm. Indeed, the power production of downstream wind turbine rows is strictly affected by the cumulative wake produced by the turbines deployed upstream. Wind turbine wakes are dependent on their aerodynamic features, and being immersed in the atmospheric boundary layer (ABL), they are also affected by surface heterogeneity, e.g. site topography and surface coverage, and atmospheric stability. The ABL stability is typically classified as neutral, convective or stable. In a neutral ABL the mechanical turbulent production is the dominating phenomenon. Conversely, for a convective ABL the turbulent kinetic energy and vertical transport phenomena are enhanced by positive buoyancy. Finally, for a stable ABL, a lower turbulence level is typically observed with an increased wind shear. For the present campaign convective ABL was typically observed during day-time, and neutral ABL for early morning and sunset periods. The aim of the present work is the evaluation of the influence of the ABL stability on downstream evolution of wind turbine wakes, which is mainly controlled by different ABL turbulence characteristics. Field measurements of the wake produced from a 2 MW Enercon E-70 wind turbine were performed with three scanning Doppler wind LiDARs. The wind and atmospheric conditions were characterized through a sonic anemometer deployed in proximity of the wind turbine. One LiDAR was placed at a distance about 12 rotor diameters upstream of the turbine in order to characterize the incoming wind. Two additional LiDARs were typically used to perform wake measurements. Tests were performed over the wake vertical symmetry plane in order to characterize wake recovery. Measurements were also carried out over conical surfaces in order to investigate the wind turbine wake with varying wind direction, thus different turbine yaw angles. Moreover, a 3D characterization of the wind turbine wake was performed by scanning the LiDAR over a 3D measurement volume. However, the large sampling period required for the 3D scans does not allow the investigation of wake dynamics. The LiDAR measurements show that wake evolution is significantly affected by the stability conditions of the ABL, thus by the different turbulence characteristics of the incoming wind. In particular, a faster wake recovery is observed in the presence of an increased turbulence of the incoming wind and for more convective atmospheric flows.

  19. High resolution t-LiDAR scanning of an active bedrock fault scarp for palaeostress analysis

    Science.gov (United States)

    Reicherter, Klaus; Wiatr, Thomas; Papanikolaou, Ioannis; Fernández-Steeger, Tomas

    2013-04-01

    Palaeostress analysis of an active bedrock normal fault scarp based on kinematic indicators is carried applying terrestrial laser scanning (t-LiDAR or TLS). For this purpose three key elements are necessary for a defined region on the fault plane: (i) the orientation of the fault plane, (ii) the orientation of the slickenside lineation or other kinematic indicators and (iii) the sense of motion of the hanging wall. We present a workflow to obtain palaeostress data from point cloud data using terrestrial laser scanning. The entire case-study was performed on a continuous limestone bedrock normal fault scarp on the island of Crete, Greece, at four different locations along the WNW-ESE striking Spili fault. At each location we collected data with a mobile terrestrial light detection and ranging system and validated the calculated three-dimensional palaeostress results by comparison with the conventional palaeostress method with compass at three of the locations. Numerous kinematics indicators for normal faulting were discovered on the fault plane surface using t-LiDAR data and traditional methods, like Riedel shears, extensional break-outs, polished corrugations and many more. However, the kinematic indicators are more or less unidirectional and almost pure dip-slip. No oblique reactivations have been observed. But, towards the tips of the fault, inclination of the striation tends to point towards the centre of the fault. When comparing all reconstructed palaeostress data obtained from t-LiDAR to that obtained through manual compass measurements, the degree of fault plane orientation divergence is around ±005/03 for dip direction and dip. The degree of slickenside lineation variation is around ±003/03 for dip direction and dip. Therefore, the percentage threshold error of the individual vector angle at the different investigation site is lower than 3 % for the dip direction and dip for planes, and lower than 6 % for strike. The maximum mean variation of the complete calculated palaeostress tensors is ±005/03. So, technically t-LiDAR measurements are in the error range of conventional compass measurements. The advantages is that remote palaeostress analysis is possible. Further steps in our research will be studying reactivated faults planes with multiple kinematic indicators or striations with t-LiDAR.

  20. Linking forest snow interception rates with LiDAR derived canopy structure data

    Science.gov (United States)

    moeser, D.; Jonas, T.; Webster, C.

    2013-12-01

    Forest architecture directly influences seasonal snow accumulation patterns creating large variations over small distances as well as on a seasonal basis. Forest snow interception rates can be reasonably estimated under various canopy cover regimes, but only if one assumes uniform canopy densities over space. In most mountain regions, forested areas exhibit a mosaic patterning of canopy coverage and gap fractions which hamper a realistic view of the interplay between forest and snow cover if basic parameterizations of forest structure are utilized. We have directly compared canopy representations traditionally utilized in many forest snowmelt models with new parameters derived from LiDAR data against interception rates. Seven 2500m2 field areas have been precisely geo-located within various canopy density/gap fractionation regimes in three elevation bands within Norwegian Spruce dominated forests in the Swiss Alps. Each grid currently contains 276 accurately geo-referenced and labelled points to +/- 50cm allowing for repeatable snow depth and SWE measurements over time and space to be directly linked to a high resolution aerial LiDAR data set available for the region. We have measured SWE, total snow depth as well as direct measurements of storm based differential depths for the 2012/2013 winter season for a total of 45000 manual measurements at all sites in order to analyze the evolution of the total underlying snow pack during accumulation. The snow storm based measurements allow for indirect measurements of interception. The LiDAR data has been manipulated at a variety of spatial scales to explicitly derive a variety of traditional parameters such as gap fraction area, leaf area index as well as a variety of new parameters such as effective gap fraction area, distance to closest stem, and LiDAR derived hemispherical photos. These canopy parameters were directly compared to the measured interception rates for correlation. The first glimpse shows highest correlations of interception rates are related to an effective gap fraction area as well as parameters gathered from the conversion of LiDAR data to a polar coordinate system.

  1. Financial sustainability in municipal solid waste management – Costs and revenues in Bahir Dar, Ethiopia

    International Nuclear Information System (INIS)

    Highlights: • Cost-revenue analysis over 2 years revealed insufficient cost-recovery. • Expenses for motorized secondary collection increased by 82% over two years. • Low fee collection rate and reliance on only one revenue stream are problematic. • Different options for cost reduction and enhanced revenue streams are recommended. • Good public–private alliance is crucial to plan and implement improvement measures. - Abstract: Providing good solid waste management (SWM) services while also ensuring financial sustainability of the system continues to be a major challenge in cities of developing countries. Bahir Dar in northwestern Ethiopia outsourced municipal waste services to a private waste company in 2008. While this institutional change has led to substantial improvement in the cleanliness of the city, its financial sustainability remains unclear. Is the private company able to generate sufficient revenues from their activities to offset the costs and generate some profit? This paper presents a cost-revenue analysis, based on data from July 2009 to June 2011. The analysis reveals that overall costs in Bahir Dar’s SWM system increased significantly during this period, mainly due to rising costs related to waste transportation. On the other hand, there is only one major revenue stream in place: the waste collection fee from households, commercial enterprises and institutions. As the efficiency of fee collection from households is only around 50%, the total amount of revenues are not sufficient to cover the running costs. This results in a substantial yearly deficit. The results of the research therefore show that a more detailed cost structure and cost-revenue analysis of this waste management service is important with appropriate measures, either by the privates sector itself or with the support of the local authorities, in order to enhance cost efficiency and balance the cost-revenues towards cost recovery. Delays in mitigating the evident financial deficit could else endanger the public-private partnership (PPP) and lead to failure of this setup in the medium to long term, thus also endangering the now existing improved and currently reliable service. We present four options on how financial sustainability of the SWM system in Bahir Dar might be enhanced: (i) improved fee collection efficiency by linking the fees of solid waste collection to water supply; (ii) increasing the value chain by sales of organic waste recycling products; (iii) diversifying revenue streams and financing mechanisms (polluter-pays-, cross-subsidy- and business-principles); and (iv) cost reduction and improved cost-effectiveness. We argue that in a PPP setup such as in Bahir Dar, a strong alliance between the municipality and private enterprise is important so that appropriate solutions for improved financial sustainability of a SWM system can be sought and implemented

  2. Flood Risk Mapping Using LiDAR for Annapolis Royal, Nova Scotia, Canada

    Directory of Open Access Journals (Sweden)

    Tim L. Webster

    2010-09-01

    Full Text Available A significant portion of the Canadian Maritime coastline has been surveyed with airborne Light Detection and Ranging (LiDAR. The purpose of these surveys has been to map the risk of flooding from storm surges and projected long-term sea?level rise from climate change and to include projects in all three Maritime Provinces: Prince Edward Island, New Brunswick, and Nova Scotia. LiDAR provides the required details in order to map the flood inundation from 1 to 2 m storm surge events, which cause coastal flooding in many locations in this region when they occur at high tide levels. The community of Annapolis Royal, Nova Scotia, adjacent to the Bay of Fundy, has been surveyed with LiDAR and a 1 m DEM (Digital Elevation Model was constructed for the flood inundation mapping. Validation of the LiDAR using survey grade GPS indicates a vertical accuracy better than 30 cm. A benchmark storm, known as the Groundhog Day storm (February 1–3, 1976, was used to assess the flood maps and to illustrate the effects of different sea-level rise projections based on climate change scenarios if it were to re-occur in 100 years time. Near shore bathymetry has been merged with the LiDAR and local wind observations used to model the impact of significant waves during this benchmark storm. Long-term (ca. greater than 30 years time series of water level observations from across the Bay of Fundy in Saint John, New Brunswick, have been used to estimate return periods of water levels under present and future sea-level rise conditions. Results indicate that under current sea-level rise conditions this storm has a 66 year return period. With a modest relative sea-level (RSL rise of 80 cm/century this decreases to 44 years and, with a possible upper limit rise of 220 cm/century, this decreases further to 22 years. Due to the uncertainty of climate change scenarios and sea-level rise, flood inundation maps have been constructed at 10 cm increments up to the 9 m contour which represents an upper flood limit estimate in 100 years, based on the highest predicted tide, plus a 2 m storm surge and a RSL of 220 cm/century.

  3. LiDAR Sampling Density for Forest Resource Inventories in Ontario, Canada

    Directory of Open Access Journals (Sweden)

    Dave Etheridge

    2012-03-01

    Full Text Available Over the past two decades there has been an abundance of research demonstrating the utility of airborne light detection and ranging (LiDAR for predicting forest biophysical/inventory variables at the plot and stand levels. However, to date there has been little effort to develop a set of protocols for data acquisition and processing that would move governments or the forest industry towards cost-effective implementation of this technology for strategic and tactical (i.e., operational forest resource inventories. The goal of this paper is to initiate this process by examining the significance of LiDAR data acquisition (i.e., point density for modeling forest inventory variables for the range of species and stand conditions representing much of Ontario, Canada. Field data for approximately 200 plots, sampling a broad range of forest types and conditions across Ontario, were collected for three study sites. Airborne LiDAR data, characterized by a mean density of 3.2 pulses m?2 were systematically decimated to produce additional datasets with densities of approximately 1.6 and 0.5 pulses m?2. Stepwise regression models, incorporating LiDAR height and density metrics, were developed for each of the three LiDAR datasets across a range of forest types to estimate the following forest inventory variables: (1 average height (R2(adj = 0.75–0.95; (2 top height (R2(adj = 0.74–0.98; (3 quadratic mean diameter (R2(adj = 0.55–0.85; (4 basal area (R2(adj = 0.22–0.93; (5 gross total volume (R2(adj = 0.42–0.94; (6 gross merchantable volume (R2(adj = 0.35–0.93; (7 total aboveground biomass (R2(adj = 0.23–0.93; and (8 stem density (R2(adj = 0.17–0.86. Aside from a few cases (i.e., average height and density for some stand types, no decimation effect was observed with respect to the precision of the prediction of the majority of forest variables, which suggests that a mean density of 0.5 pulses m?2 is sufficient for plot and stand level modeling under these diverse forest conditions across Ontario.

  4. 3D turbulence measurements using three intersecting Doppler LiDAR beams: validation against sonic anemometry

    Science.gov (United States)

    Carbajo Fuertes, Fernando; Valerio Iungo, Giacomo; Porté-Agel, Fernando

    2013-04-01

    Nowadays communities of researchers and industry in the wind engineering and meteorology sectors demand extensive and accurate measurements of atmospheric boundary layer turbulence for a better understanding of its role in a wide range of onshore and offshore applications: wind resource evaluation, wind turbine wakes, meteorology forecast, pollution and urban climate studies, etc. Atmospheric turbulence has been traditionally investigated through sonic anemometers installed on meteorological masts. However, the setup and maintenance of instrumented masts is generally very costly and the available location for the measurements is limited by the fixed position and height of the facility. In order to overcome the above-mentioned shortcomings, a measurement technique is proposed, based on the reconstruction of the three-dimensional velocity vector from simultaneous measurements of three intersecting Doppler wind LiDARs. This measuring technique presents the main advantage of being able to measure the wind velocity at any point in space inside a very large volume, which can be set and optimized for each test. Furthermore, it is very flexible regarding its transportation, installation and operation in any type of terrain. On the other hand, LiDAR measurements are strongly affected by the aerosol concentration in the air, precipitation, and the spatial and temporal resolution is poorer than that of a sonic anemometer. All this makes the comparison between these two kinds of measurements a complex task. The accuracy of the technique has been assessed by this study against sonic anemometer measurements carried out at different heights on the KNMI's meteorological mast at Cabauw's experimental site for atmospheric research (CESAR) in the Netherlands. An early uncertainty analysis shows that one of the most important parameters to be taken into account is the relative angles between the intersecting laser beams, i.e., the position of each LiDAR on the terrain and their elevation and azimuth angles. Following this analysis, different LiDAR layouts have been tested, e.g., one vertical beam and the other two almost horizontal, all three equidistant with the same elevation angle, etc. Preliminary results show different degrees of agreement between the proposed technique and the sonic anemometers depending on the LiDARs layout, which is in agreement with the uncertainty analysis carried out. The best configurations show a good agreement for the three components of the velocity and turbulence spectra, thus proving the ability of the technique to measure accurately atmospheric turbulence, consolidating it as a very interesting alternative to meteorological masts for many different applications.

  5. DArT markers for the rye genome - genetic diversity and mapping

    Directory of Open Access Journals (Sweden)

    Kilian Andrzej

    2009-12-01

    Full Text Available Abstract Background Implementation of molecular breeding in rye (Secale cereale L. improvement programs depends on the availability of high-density molecular linkage maps. However, the number of sequence-specific PCR-based markers available for the species is limited. Diversity Arrays Technology (DArT is a microarray-based method allowing for detection of DNA polymorphism at several thousand loci in a single assay without relying on DNA sequence information. The objective of this study was the development and application of Diversity Arrays technology for rye. Results Using the PstI/TaqI method of complexity reduction we created a rye diversity panel from DNA of 16 rye varieties and 15 rye inbred lines, including parents of a mapping population consisting of 82 recombinant inbred lines. The usefulness of a wheat diversity panel for identification of DArT markers for rye was also demonstrated. We identified 1022 clones that were polymorphic in the genotyped ILs and varieties and 1965 clones that differentiated the parental lines L318 and L9 and segregated in the mapping population. Hierarchical clustering and ordination analysis were performed based on the 1022 DArT markers to reveal genetic relationships between the rye varieties and inbred lines included in the study. Chromosomal location of 1872 DArT markers was determined using wheat-rye addition lines and 1818 DArT markers (among them 1181 unique, non-cosegregating were placed on a genetic linkage map of the cross L318 × L9, providing an average density of one unique marker every 2.68 cM. This is the most saturated rye linkage map based solely on transferable markers available at the moment, providing rye breeders and researches with a better choice of markers and a higher probability of finding polymorphic markers in the region of interest. Conclusion The Diversity Arrays Technology can be efficiently and effectively used for rye genome analyses - assessment of genetic similarity and linkage mapping. The 11520-clone rye genotyping panel with several thousand markers with determined chromosomal location and accessible through an inexpensive genotyping service is a valuable resource for studies on rye genome organization and in molecular breeding of the species.

  6. Buildings classification from airborne LiDAR point clouds through OBIA and ontology driven approach

    Science.gov (United States)

    Tomljenovic, Ivan; Belgiu, Mariana; Lampoltshammer, Thomas J.

    2013-04-01

    In the last years, airborne Light Detection and Ranging (LiDAR) data proved to be a valuable information resource for a vast number of applications ranging from land cover mapping to individual surface feature extraction from complex urban environments. To extract information from LiDAR data, users apply prior knowledge. Unfortunately, there is no consistent initiative for structuring this knowledge into data models that can be shared and reused across different applications and domains. The absence of such models poses great challenges to data interpretation, data fusion and integration as well as information transferability. The intention of this work is to describe the design, development and deployment of an ontology-based system to classify buildings from airborne LiDAR data. The novelty of this approach consists of the development of a domain ontology that specifies explicitly the knowledge used to extract features from airborne LiDAR data. The overall goal of this approach is to investigate the possibility for classification of features of interest from LiDAR data by means of domain ontology. The proposed workflow is applied to the building extraction process for the region of "Biberach an der Riss" in South Germany. Strip-adjusted and georeferenced airborne LiDAR data is processed based on geometrical and radiometric signatures stored within the point cloud. Region-growing segmentation algorithms are applied and segmented regions are exported to the GeoJSON format. Subsequently, the data is imported into the ontology-based reasoning process used to automatically classify exported features of interest. Based on the ontology it becomes possible to define domain concepts, associated properties and relations. As a consequence, the resulting specific body of knowledge restricts possible interpretation variants. Moreover, ontologies are machinable and thus it is possible to run reasoning on top of them. Available reasoners (FACT++, JESS, Pellet) are used to check the consistency of the developed ontologies, and logical reasoning is performed to infer implicit relations between defined concepts. The ontology for the definition of building is specified using the Ontology Web Language (OWL). It is the most widely used ontology language that is based on Description Logics (DL). DL allows the description of internal properties of modelled concepts (roof typology, shape, area, height etc.) and relationships between objects (IS_A, MEMBER_OF/INSTANCE_OF). It captures terminological knowledge (TBox) as well as assertional knowledge (ABox) - that represents facts about concept instances, i.e. the buildings in airborne LiDAR data. To assess the classification accuracy, ground truth data generated by visual interpretation and calculated classification results in terms of precision and recall are used. The advantages of this approach are: (i) flexibility, (ii) transferability, and (iii) extendibility - i.e. ontology can be extended with further concepts, data properties and object properties.

  7. Accuracy of Forest Road and Stream Channel Characteristics Derived from LiDAR Terrain Data in Forested Mountain Conditions

    Science.gov (United States)

    White, R. A.; Dietterick, B. C.

    2008-12-01

    Airborne LiDAR data is now commonly used to create digital elevation models with a vertical accuracy and grid resolution that surpasses traditional sources of topographic data. The improved topographic detail of LiDAR-derived DEMs allows for identification and measurement of important topographic features including forest roads, historic landslides and potentially unstable areas. When used conjunction with GIS-based flow accumulation algorithms, high-resolution DEMs can also provide improvements to the positional accuracy, longitudinal profile, stream lengths of topographically-derived stream channels. LiDAR data collected over forested and steep terrain however, requires careful evaluation. The reduced density and variable spacing of LiDAR ground returns, which is often encountered in these settings, reduces the effective resolution of LiDAR DEMs and may limit fine-scale topographic mapping. This study tested the completeness and accuracy forest road and stream channel features mapped using a 1.5 m LiDAR-derived DEM for a 526-hectare watershed in the Santa Cruz mountains in California. Positional accuracy, longitudinal slope and length of LiDAR-derived features were compared to field-survey measurements obtained using total station. LiDAR-derived measurements were also compared to measurements from traditional data sources such as a USGS 10 m DEM and a 1 m orthophoto. The LiDAR- derived road was manually digitized from the LiDAR hillshade and slope layers, with a positional accuracy of 2.2 m normal to the field-surveyed centerline. LiDAR-derived road slope was accurate to within 0.59% of field-surveyed slope at a 95% confidence interval. The entire 4 km road length could be mapped using the LiDAR data. Due to the dense overstory canopy only 18% of that road length could be identified from the orthophoto. Stream channel features derived using Arc Hydro were compared to field-surveyed data at six 100 m study reaches. The average positional accuracy of the derived channel locations was 2.7 m normal to the field- surveyed thalweg. Longitudinal channel slope was measured to within 0.49% compared to the field- surveyed slope while channel length was underestimated by an average of 6 percent. These measurements provided an improvement over the features derived from the USGS 10 m DEM, where channel features had a positional accuracy of 8.7 m, channel length was underestimated by 11% and had a longitudinal slope error was one order of magnitude greater than the LiDAR-derived measurement. These findings indicate that even in densely forested areas, LiDAR has the potential to support accurate, watershed-wide inventories of forest road and stream channel features, which can contribute to our understanding road erosion, sediment transport, and their effects on the stream channel network.

  8. Classification and extraction of trees and buildings from urban scenes using discrete return LiDAR and aerial color imagery

    Science.gov (United States)

    Bandyopadhyay, Madhurima; van Aardt, Jan A. N.; Cawse-Nicholson, Kerry

    2013-05-01

    Airborne Light Detection and Ranging (LiDAR) is used in many 3D applications, such as urban planning, city modeling, facility management, and environmental assessments. LiDAR systems generate dense 3D point clouds, which provide a distinct and comprehensive geometrical description of object surfaces. However, the challenge is that most of the applications require correct identification and extraction of objects from LiDAR point clouds to facilitate quantitative descriptions. This paper presents a feature-level fusion approach between LiDAR and aerial color (RGB) imagery to separate urban vegetation and buildings from other urban classes/cover types. The classification method used structural and spectral features derived from LiDAR and RGB imagery. Features such as flatness and distribution of normal vectors were estimated from LiDAR data, while the non-calibrated normalized difference vegetation index (NDVI) was calculated by combining LiDAR intensity at 1064 nm with the red channel from the RGB imagery. Building roof tops have regular surfaces with smaller variation in surface normal, whereas tree points generate irregular surfaces. Tree points, on the other hand, exhibit higher NDVI values when compared to returns from other classes. To identify vegetation points an NDVI map was used, while a vegetation mask was also derived from the RGB imagery. Accuracy was assessed by comparing the extraction result with manually digitized reference data generated from the high spatial resolution RGB image. Classification results indicated good separation between building and vegetation and exhibited overall accuracies greater than 85%.

  9. O Édipo de Foucault não é o de Freud/El Edipo de Foucault no es de Freud

    Directory of Open Access Journals (Sweden)

    Marcelo Ricardo Pereira

    2010-03-01

    Full Text Available O Édipo, como o homem que sabia demais, era por isso o homem da ignorância. Foucault, diferente de Freud, estabelece um Édipo historicizado no tempo da passagem da forma jurídica do “regime de provas” à do “sistema de inquérito”, culminando no que chamou de o “exame” – nome lacônico que dá às ciências humanas. Porém, não há como mencionar a tragédia sofocliana sem tocar na hermenêutica psicanalítica, e sobre isso Foucault é implacável: a Psicanálise é um dispositivo discursivo de poder, uma ciência disciplinar, contendora do desejo. Mas a Psicanálise não deve ser emparelhada à Psiquiatria, por exemplo. A “razão” freudiana reside justamente numa tensão paradoxal entre dar voz à singularidade e, ao mesmo tempo, reafirmar universais históricos da cultura. Édipo não é uma nosografia, mas o que detém um “saber que não se sabe”: o do inconsciente. Se ele é o homem do inconsciente em Freud, em Foucault ele será o da ignorância. Nisso, ambos se confluem: o homem moderno para sempre está “dissolvido”. Edipo, como el hombre que sabía demasiado, era el hombre de la ignorancia. Foucault, a diferencia de Freud, establece un Edipo historizado en el tiempo de la pasaje de la forma jurídica del "régimen de pruebas" al “sistema de averiguación", que culmina en lo que él llamó la "examem" - nombre lacónico que él da a las humanidades. Sin embargo, no se menciona la tragedia de Sófocles, sin tocar en la hermenéutica del psicoanálisis, y Foucault es implacable: el psicoanálisis es un dispositivo discursivo del poder, una ciencia disciplinar, contendiente del deseo. Pero el psicoanálisis no debería ser emparejados a la psiquiatría, por ejemplo. La "razón" freudiana reside en una tensión paradójica entre dar voz a la singularidad y, al mismo tiempo, reafirmar los universales históricos de la cultura. Edipo no es una nosografia, pero lo que tiene un "saber que no se sabe": el inconsciente. Si él es el hombre del inconsciente en Freud, en Foucault él será de la ignorancia. En este sentido, ambos confluyen: el hombre moderno para siempre está "disuelto".

  10. Correlating the Horizontal and Vertical Distribution of LiDAR Point Clouds with Components of Biomass in a Picea crassifolia Forest

    OpenAIRE

    Wang Li; Zheng Niu; Shuai Gao; Ni Huang; Hanyue Chen

    2014-01-01

    Light detection and ranging (LiDAR) has been widely used to estimate forest biomass. In this study, we aim to further explore this capability by correlating horizontal and vertical distribution of LiDAR data with components of biomass in a Picea crassifolia forest. Airborne small footprint full-waveform data were decomposed to acquire higher density point clouds. We calculated LiDAR metrics at the tree level and subplot level and correlated them to biomass components, including branch biomass...

  11. Improving Measurement of Forest Structural Parameters by Co-Registering of High Resolution Aerial Imagery and Low Density LiDAR Data

    OpenAIRE

    Huang, Huabing; Gong, Peng; Cheng, Xiao; Clinton, Nick; Li, Zengyuan

    2009-01-01

    Forest structural parameters, such as tree height and crown width, are indispensable for evaluating forest biomass or forest volume. LiDAR is a revolutionary technology for measurement of forest structural parameters, however, the accuracy of crown width extraction is not satisfactory when using a low density LiDAR, especially in high canopy cover forest. We used high resolution aerial imagery with a low density LiDAR system to overcome this shortcoming. A morphological filtering was used to ...

  12. ¿Es Paracoccidioides brasiliensis un grupo monofilético?

    Directory of Open Access Journals (Sweden)

    Juan Mcewen

    2001-04-01

    Full Text Available

    Paracoccidioides brasiliensis es un hongo dimórfico térmico
    causante de la paracoccidioidomicosis, micosis de alta prevalencia en América Latina. Colombia ocupa el segundo lugar en endemicidad, después de Brasil. Su presentación clínica es, usualmente, de carácter crónico y en ausencia de una terapia efectiva la paracoccidioidomicosis progresa y puede ser letal en muchos casos (1. Actualmente el Paracoccidioides se ha considerado un grupo homogéneo y se le ha identificado la especie brasiliensis como única. Sin embargo, varios estudios
    han demostrado variaciones genéticas que han permitido agrupar las cepas de acuerdo con su origen geográfico, pero no se conoce si estas variaciones puedan generar o ser el producto de especies aisladas geográficamente (2. Adicionalmente, se ha mostrado una correlación entre patrones de RAPD de los aislamientos clínicos del hongo y su habilidad para causar enfermedad experimental de diferente severidad (3. Estos hallazgos sugieren que P. brasiliensis podría estar distribuido en diferentes grupos monofiléticos.

     

     

  13. La diversidad (in)visible: Identidad(es) entre policías bonaerenses

    Scientific Electronic Library Online (English)

    José, Garriga Zucal; Mariano, Melotto.

    2013-04-01

    Full Text Available En este artículo analizamos cómo se construye el “nosotros” policial, entendiendo que el mismo no responde a una construcción estable y perenne propia de una esencia ontológica invariable del “ser policial”; sino que, por el contrario, es el resultado voluble y mutante de las múltiples relaciones so [...] ciales. Para dar cuenta de esta construcción estudiaremos algunos clivajes internos de la institución policial, exhibiendo la diversidad de vínculos sociales existentes en el interior de una grupalidad que se presenta como homogénea. La imagen del “verdadero policía”, idealización del hacer policial y su representación, nos permitirá rastrear la construcción de una distinción para con la sociedad, al mismo tiempo, que pondrá luz sobre la heterogeneidad opacada. Abstract in english In this article we analyze how the "we" police is built, understanding that it does not respond to a stable and permanent construction, typical of an invariable ontological essence of "being police", but on the contrary, it is the result of fickle and mutant multiple social relations. To account for [...] this construction we will study some police internal cleavages, showing the diversity of existing social ties within a groupality presented as homogeneous. The image of the "real police", idealized representation of police doing, will allow us to track the construction of a distinction to society, at the same time it will light up the obscured heterogeneity.

  14. ¿Es posible ser moralmente responsable? Notas para una nueva definición del concepto de sujeto

    Directory of Open Access Journals (Sweden)

    Raga Rosaleny, Vicente

    2006-04-01

    Full Text Available The Strawson´s Basic Argument is the stronger against moral responsibility in Philosophy of action. One should be responsible of his identity to be moral responsible of his actions, but then nobody could be never responsible. In this article I criticize orthodox solutions to Strawson´s sceptical challenge and show how they share with the Argument the same theological notion of monadical agent. A new solution needs a new conception of agent..Una de las objeciones más fuertes contra la responsabilidad moral en filosofía de la acción sería el Argumento Básico de Galen Strawson, que plantea la necesidad de que uno sea responsable de ser quien es para poder ser responsable moralmente de sus acciones, exigencia ésta harto difícil o imposible de cumplir por lo que, en consecuencia, nadie sería nunca responsable. Los diversas respuestas ortodoxas al reto escéptico de Strawson comparten con el Argumento Básico una misma noción teológica heredada de agente-mónada y, según trato de mostrar en mi artículo, sería necesaria una nueva concepción del sujeto para dar cuenta correctamente de este Argumento.

  15. Slip vector analysis with high resolution t-LiDAR scanning

    Science.gov (United States)

    Wiatr, Thomas; Reicherter, Klaus; Papanikolaou, Ioannis; Fernández-Steeger, Tomás; Mason, Jack

    2013-11-01

    A palaeostress analysis of an active bedrock normal fault scarp based on kinematic indicators is reconstructed using terrestrial laser scanning (TLS). For this purpose, three key elements are necessary for a defined region: (i) the orientation of the fault plane, (ii) the orientation of the slickenside lineation or other kinematic indicators, and (iii) the sense of motion of the hanging wall. The paper specifies a workflow in order to obtain stress data from point cloud data using terrestrial laser scanning (TLS) in an active tectonic environment. The entire analysis was performed on a continuous limestone bedrock normal fault scarp on the island of Crete, Greece, at four different locations along the WNW-ESE striking Spili Fault. At each location we collected data with the terrestrial light detection and ranging system (t-LiDAR). We then validated the calculated three-dimensional stress results at three of the locations by comparison with conventional methods using data obtained manually with a compass clinometer. Numerous kinematic indicators for normal faulting were discovered on the fault plane surface using t-LiDAR data. When comparing all reconstructed stress data obtained from t-LiDAR to that obtained through manual compass measurements, the degree of fault plane orientation divergence is ± 005/03 for dip direction and dip. The degree of slickenside lineation divergence is ± 003/03 for dip direction and dip. Therefore, the percentage threshold error of the individual vector angle at each investigation site is lower than 3% for the dip direction and dip for planes, and lower than 6% for the strike. The maximum mean variation of the complete calculated stress tensors is ± 005/03.

  16. Development of a UAV-LiDAR System with Application to Forest Inventory

    Directory of Open Access Journals (Sweden)

    Darren Turner

    2012-05-01

    Full Text Available We present the development of a low-cost Unmanned Aerial Vehicle-Light Detecting and Ranging (UAV-LiDAR system and an accompanying workflow to produce 3D point clouds. UAV systems provide an unrivalled combination of high temporal and spatial resolution datasets. The TerraLuma UAV-LiDAR system has been developed to take advantage of these properties and in doing so overcome some of the current limitations of the use of this technology within the forestry industry. A modified processing workflow including a novel trajectory determination algorithm fusing observations from a GPS receiver, an Inertial Measurement Unit (IMU and a High Definition (HD video camera is presented. The advantages of this workflow are demonstrated using a rigorous assessment of the spatial accuracy of the final point clouds. It is shown that due to the inclusion of video the horizontal accuracy of the final point cloud improves from 0.61 m to 0.34 m (RMS error assessed against ground control. The effect of the very high density point clouds (up to 62 points per m2 produced by the UAV-LiDAR system on the measurement of tree location, height and crown width are also assessed by performing repeat surveys over individual isolated trees. The standard deviation of tree height is shown to reduce from 0.26 m, when using data with a density of 8 points perm2, to 0.15mwhen the higher density data was used. Improvements in the uncertainty of the measurement of tree location, 0.80 m to 0.53 m, and crown width, 0.69 m to 0.61 m are also shown.

  17. Active Normal Faulting in Northern Taiwan: Evidence from LiDAR-derived DTM and Geologic Observations

    Science.gov (United States)

    Chan, Y.; Chang, K.; Chen, R.; Lee, J.; Hsieh, Y.

    2009-12-01

    Complex tectonic environment occurs in northern Taiwan where the Philippine Sea plate is subducting underneath the Eurasian plate. In contrast to other parts of the contractional Taiwan mountain belt, the northern Taiwan area currently undergoes extensional tectonics which may potentially induce destructive normal fault earthquakes around the Taipei metropolitan area. However, mapped active faults in the region are still under debate due to lack of clear evidence; hence, crucial work is needed to determine reliable evidence and pattern of active normal faulting. In order to uncover decisive topographic evidence, we initiated and applied airborne LiDAR topographic mapping in northern Taiwan to virtually remove trees and buildings. Based on recent LiDAR-derived DTM and geologic observations, we discovered consistent evidence for regional extensional deformation in northern Taiwan. We uncovered fracture patterns and branches of normal faults possibly extending from the Shanchiao normal fault into the Tatun volcanic region. We also discovered clear topographic evidence for normal faulting preserved in densely-covered forests within the hard-to-reach mountainous region. The newly acquired LiDAR-derived DTM indicates a series of topographic offsets of a few meters indicating possibly active normal faulting in the region. Furthermore, the discovered topographic offsets seem distributed in a zone of several kilometers suggesting that the effect of extension is distributed rather than localized in one single fault. Several sag ponds or dammed lakes were present, which further support pervasive normal faulting activities. In addition, lake sediment study indicates regional subsidence in the Lanyang Plain area at a rate comparable or higher to that for the Taipei Basin. As indicated by the well-preserved surface ruptures under forests and the long-term subsidence rates, these geologic findings remind us that the northern Taiwan region may well produce destructive normal fault earthquakes with shallow hypocenters although recent GPS and seismicity observations reveal only modest tectonic activities.

  18. Molecular multi-effect screening of environmental pollutants using the MolDarT.

    Science.gov (United States)

    Liedtke, Anja; Muncke, Jane; Rüfenacht, Karin; Eggen, Rik I L

    2008-02-01

    Molecular effect detection is a useful approach for ecotoxicological screening of chemicals. We show here the application of the molecular DarT (MolDarT), where the expression of selected target genes is detected in short-term (120 h) exposed developing zebrafish (Danio rerio), thus allowing subacute multi-effect compound screening. The genes metallothionein 2 (mt2), cytochrome P450 1A1 (cyp1a1), and recombination activation gene 1 (rag1) are used as endpoints that describe detoxification/metal toxicity (mt2), detoxification/PAH toxicity (cyp1a1), and acquired immune system disruption (rag1). Each gene's developmental expression was studied in unexposed zebrafish during 4 to 120 h past fertilization (hpf), and all three genes were found to be expressed at 120 hpf. Furthermore, mt2 transcripts were present at high levels at 4 hpf, indicating a maternal transfer. For positive toxicity controls, freshly fertilized zebrafish eggs were exposed for 120 hpf to ZnSO(4), 1,5-dimethylnaphthalene (DMN) and CdCl(2). Exposure to 100 and 200 microM ZnSO(4) significantly induced mt2; 10 microM DMN and 20 microM DMN resulted in significantly increased cyp1a1 abundance; and 5 and 10 microM CdCl(2) significantly reduced rag1 expression levels. Furthermore, we analysed these target genes for their expression in zebrafish eggs from a previous exposure study. The eggs were exposed for 120 hpf to the environmental pollutants estradiol (E2), ethinylestradiol (EE2), nonylphenol (NP), atrazine, cyproconazol, and bisphenol A (BPA) and found differential expression of the three genes. Exposure to the (xeno-)estrogenic compound NP (0.75 microM) significantly lowered mt2 expression. This study shows the potential of short-term in vivo multi-effect screenings within one single subacute exposure using the MolDarT. PMID:18214934

  19. Classification of breaklines derived from airborne LiDAR data for geomorphological activity mapping

    Science.gov (United States)

    Rutzinger, Martin; Höfle, Bernhard; Vetter, Michael; Stötter, Johann; Pfeifer, Norbert

    2010-05-01

    Airborne LiDAR surveys provide 3D high-resolution elevation information for area-wide applications. Due to the capability of LiDAR to penetrate vegetation cover highly accurate digital terrain models (DTMs) can be derived also for forested areas. Breaklines derived from LiDAR DTMs mark regions of slope discontinuities, describing the main characteristics of a terrain surface in an efficient manner. Breaklines are often used for DTM enhancement but also for the detection and interpretation of geomorphologically relevant landforms such as landslides, torrents, erosion scraps and tectonic faults. Because of human activities geomorphologic landforms are often disturbed and reshaped i.e. by construction of roads, skiing slopes, drainage channels and surface mining. Therefore, DTMs contain both, anthropogenic and geomorphologic discontinuities. This significantly disturbs morphometric analysis and causes problems for automatic landform mapping algorithms. In this research an automatic breakline detection method is applied in an alpine region with high relief variation containing surface discontinuities such as torrents, creeping slope failure, and landslides, which are reshaped by anthropogenic activities. Regions of high curvature are classified and vectorised in order to derive 3D breaklines. These are further filtered and classified based on object-based properties such as their size, shape and slope to separate natural i.e. geomorphologic relevant and anthropogenic structures. The classification result is compared to reference map data indicating a high reliability of the classification quality. After the removal of anthropogenic breaklines the remaining natural breaklines are used to compute line density maps using a moving window approach. These density maps point out areas of different relief energy and assist to delineate areas of geomorphologic relevance. These areas are also of most interest to identify geomorphological landforms. The methodology presented contributes to enhance automated geomorphological mapping and process interpretation tasks in regions with high relief energy.

  20. Investigation on the contribution of LiDAR data in 3D cadastre

    Science.gov (United States)

    Giannaka, Olga; Dimopoulou, Efi; Georgopoulos, Andreas

    2014-08-01

    The existing 2D cadastral systems worldwide cannot provide a proper registration and representation of the land ownership rights, restrictions and responsibilities in a 3D context, which appear in our complex urban environment. ?n such instances, it may be necessary to consider the development of a 3D Cadastre in which proprietary rights acquire appropriate three-dimensional space both above and below conventional ground level. Such a system should contain the topology and the coordinates of the buildings' outlines and infrastructure. The augmented model can be formed as a full 3D Cadastre, a hybrid Cadastre or a 2D Cadastre with 3D tags. Each country has to contemplate which alternative is appropriate, depending on the specific situation, the legal framework and the available technical means. In order to generate a 3D model for cadastral purposes, a system is required which should be able to exploit and represent 3D data such as LiDAR, a remote sensing technology which acquires three-dimensional point clouds that describe the earth's surface and the objects on it. LiDAR gives a direct representation of objects on the ground surface and measures their coordinates by analyzing the reflecting light. Moreover, it provides very accurate position and height information, although direct information about the objects' geometrical shape is not conveyed. In this study, an experimental implementation of 3D Cadastre using LiDAR data is developed, in order to investigate if this information can satisfy the specifications that are set for the purposes of the Hellenic Cadastre. GIS tools have been used for analyzing DSM and true orthophotos of the study area. The results of this study are presented and evaluated in terms of usability and efficiency.

  1. A LiDAR-based approach for a multi-purpose characterization of Alpine forests: an Italian case study

    Directory of Open Access Journals (Sweden)

    Alberti G

    2013-04-01

    Full Text Available Several studies have verified the suitability of LiDAR for the estimation of forest metrics over large areas. In the present study we used LiDAR as support for the characterization of structure, volume, biomass and naturalistic value in mixed-coniferous forests of the Alpine region. Stem density, height and structure in the test plots were derived using a mathematical morphology function applied directly on the LiDAR point cloud. From these data, digital maps describing the horizontal and vertical forest structure were derived. Volume and biomass were then computed using regression models. A strong agreement (accuracy of the map = 97%, Kappa Cohen = 94% between LiDAR land cover map (i.e., bare soil, forest, shrubs and ground data was found, while a moderate agreement between coniferous/broadleaf map derived from LiDAR data and ground surveys was detected (accuracy = 73%, Kappa Cohen = 60%. An analysis of the forest structure map derived from LiDAR data revealed a prevalence of even-age stands (66% in comparison to the multilayered and uneven-aged forests (20%. In particular, the even-age stands, whether adult or mature, were overwhelming (33%. A moderate agreement was then detected between this map and ground data (accuracy = 68%, Kappa Cohen = 58%. Moreover, strong correlations between LiDAR-estimated and ground-measured volume and aboveground carbon stocks were detected. Related observations also showed that stem density can be rightly estimated for adult and mature forests, but not for younger categories, because of the low LiDAR posting density (2.8 points m-2. Regarding environmental issues, this study allowed us to discriminate the different contribution of LiDAR-derived forest structure to biodiversity and ecological stability. In fact, a significant difference in floristic diversity indexes (species richness - R, Shannon index - H’ was found among structural classes, particularly between pole wood (R=15 and H’=2.8; P <0.01 and multilayer forest (R=31 and H’=3.4 or thicket (R=28 and H’=3.4 where both indexes reached their maximum values.

  2. Interoperable Data Systems for Satellite, Airborne, and Terrestrial LiDAR Data

    Science.gov (United States)

    Meertens, C. M.; Baru, C.; Blair, B.; Crosby, C. J.; Haran, T. M.; Harding, D. J.; Hofton, M. A.; Khalsa, S. S.; McWhirter, J.

    2010-12-01

    LiDAR (Light Detection and Ranging) technology is being widely applied to scientific problems on global to local scales using a range of laser technologies mounted on satellite, low- and high-altitude airborne and terrestrial platforms. Modern laser ranging instruments are increasingly capable of providing full waveform data, multiple detectors, higher sample rates and longer ranges. Accompanying these improvements, however, are rapidly growing data volumes and ever more complex data formats and processing algorithms. This presents significant challenges for existing Earth science data systems serving these data and creates barriers to the efficient use of these data by a growing and diverse community of scientific and other users who are studying deformation of the solid Earth, the cryosphere, vegetation structure, and land form evolution. To address these challenges, a group of data centers is collaborating under a project funded by the NASA ROSES ACCESS Program to develop interoperable LiDAR data access systems to provide integrated access to data and derived products in common data formats via simple-to-navigate web interfaces. The web service-based systems created by this project, called NLAS, will enhance access to existing laser data sources hosted at the National Snow and Ice Data Center DAAC, Goddard Space Flight Center LVIS Data Center, UNAVCO, and the OpenTopography Facility at the San Diego Supercomputer Center (SDSC). Through the OpenTopography portal, NLAS systems will provide access to satellite laser altimetry data from ICESat and high altitude airborne laser scanning data from LVIS, as well as low altitude airborne LiDAR and terrestrial laser scanning data hosted at OpenTopography and UNAVCO. NLAS will develop new web service interfaces for NASA data archives at GSFC/LVIS and NSIDC in an effort to improve and streamline access to these data archives. The OpenTopography portal will act as a client to the NLAS services and will provide integrated access to the GSFC and NSIDC-hosted datasets along with OpenTopography hosted data. This interoperable system will provide access to LiDAR point data as well as on-demand processing capability for user-specified topographic data products. Web service -based access and integration of these distributed data archives via an easy-to-use web portal will increase usability and enhance exposure for these data.

  3. Unsupervised building detection from irregularly spaced LiDAR and aerial imagery

    Science.gov (United States)

    Shorter, Nicholas Sven

    As more data sources containing 3-D information are becoming available, an increased interest in 3-D imaging has emerged. Among these is the 3-D reconstruction of buildings and other man-made structures. A necessary preprocessing step is the detection and isolation of individual buildings that subsequently can be reconstructed in 3-D using various methodologies. Applications for both building detection and reconstruction have commercial use for urban planning, network planning for mobile communication (cell phone tower placement), spatial analysis of air pollution and noise nuisances, microclimate investigations, geographical information systems, security services and change detection from areas affected by natural disasters. Building detection and reconstruction are also used in the military for automatic target recognition and in entertainment for virtual tourism. Previously proposed building detection and reconstruction algorithms solely utilized aerial imagery. With the advent of Light Detection and Ranging (LiDAR) systems providing elevation data, current algorithms explore using captured LiDAR data as an additional feasible source of information. Additional sources of information can lead to automating techniques (alleviating their need for manual user intervention) as well as increasing their capabilities and accuracy. Several building detection approaches surveyed in the open literature have fundamental weaknesses that hinder their use; such as requiring multiple data sets from different sensors, mandating certain operations to be carried out manually, and limited functionality to only being able to detect certain types of buildings. In this work, a building detection system is proposed and implemented which strives to overcome the limitations seen in existing techniques. The developed framework is flexible in that it can perform building detection from just LiDAR data (first or last return), or just nadir, color aerial imagery. If data from both LiDAR and aerial imagery are available, then the algorithm will use them both for improved accuracy. Additionally, the proposed approach does not employ severely limiting assumptions thus enabling the end user to apply the approach to a wider variety of different building types. The proposed approach is extensively tested using real data sets and it is also compared with other existing techniques. Experimental results are presented.

  4. Landslide displacement vectors derived from multi-temporal topographic LiDAR data

    Science.gov (United States)

    Fey, Christine; Rutzinger, Martin; Bremer, Magnus; Prager, Christoph; Zangerl, Christian

    2014-05-01

    Information about slope geometry and kinematics of landslides is essential for hazard assessment, monitoring and planning of protection and mitigation measures. Especially for remote and inaccessible slopes, subsurface data (e.g. boreholes, tunnels, investigation adits) are often not available and thus the deformation characteristics must be derived from surface displacement data. In recent years, multi-temporal topographic LiDAR (Light Detection and Ranging) data became an increasingly improved tool for detecting topographic surface deformations. In this context, LiDAR-based change detection is commonly applied for quantifying surface elevation changes. Advanced change detection methods derive displacement vectors with direction and velocities of slope movements. To extract displacement vectors from LiDAR raster data (i) an approach based on feature tracking by image correlation and (ii) an approach based on feature tracking by vectors breaklines are investigated. The image correlation method is based on the IMCORR software (National Snow and Ice Data Center, University of Colorado, Boulder), implemented in a SAGA GIS module. The image correlation algorithm is based on a normalized cross-covariance method. The algorithm searches tie points in two feature rasters derived from a digital surface model acquired at different time stamps. The method assesses automatically the displacement rates and directions of distinct terrain features e.g. displaced mountain ridges or striking boulders. In contrast the vector-based breakline methods require manual selection of tie points. The breaklines are the product of vectorized curvature raster images and extracting the "upper terrain edges" (topographic ridges) and "lower terrain edges" (topographic depressions). Both methods were tested on simulated terrain with determined displacement rates in order to quantify i) the accuracy ii) the minimum detectable movement rates iii) the influence of terrain characteristics iv) the influence of input raster cell size and v) the influence of method parameter settings. Both methods were applied to investigate the development of an active rockslide in high mountain terrain. As a result, both methods yield reasonable data in order to differentiate between landslide areas and stable terrain as well as document the kinematic development of different sub-slabs within the landslide masses (featuring different movement directions and rates). Limitations are given for areas with large displacements and complex bedrock deformation, where automatic feature-tracking lead to wrong correlation results and tie points do not coincide with real displaced features. For complex deformation mechanism only the analysis method based on breaklines and manual tie point identification is suitable for vector extraction. Automated spatial analyses of topographic LiDAR data are a fundamental support to answer a variety of morphological-geological and monitoring questions.

  5. Financial sustainability in municipal solid waste management--costs and revenues in Bahir Dar, Ethiopia.

    Science.gov (United States)

    Lohri, Christian Riuji; Camenzind, Ephraim Joseph; Zurbrügg, Christian

    2014-02-01

    Providing good solid waste management (SWM) services while also ensuring financial sustainability of the system continues to be a major challenge in cities of developing countries. Bahir Dar in northwestern Ethiopia outsourced municipal waste services to a private waste company in 2008. While this institutional change has led to substantial improvement in the cleanliness of the city, its financial sustainability remains unclear. Is the private company able to generate sufficient revenues from their activities to offset the costs and generate some profit? This paper presents a cost-revenue analysis, based on data from July 2009 to June 2011. The analysis reveals that overall costs in Bahir Dar's SWM system increased significantly during this period, mainly due to rising costs related to waste transportation. On the other hand, there is only one major revenue stream in place: the waste collection fee from households, commercial enterprises and institutions. As the efficiency of fee collection from households is only around 50%, the total amount of revenues are not sufficient to cover the running costs. This results in a substantial yearly deficit. The results of the research therefore show that a more detailed cost structure and cost-revenue analysis of this waste management service is important with appropriate measures, either by the privates sector itself or with the support of the local authorities, in order to enhance cost efficiency and balance the cost-revenues towards cost recovery. Delays in mitigating the evident financial deficit could else endanger the public-private partnership (PPP) and lead to failure of this setup in the medium to long term, thus also endangering the now existing improved and currently reliable service. We present four options on how financial sustainability of the SWM system in Bahir Dar might be enhanced: (i) improved fee collection efficiency by linking the fees of solid waste collection to water supply; (ii) increasing the value chain by sales of organic waste recycling products; (iii) diversifying revenue streams and financing mechanisms (polluter-pays-, cross-subsidy- and business-principles); and (iv) cost reduction and improved cost-effectiveness. We argue that in a PPP setup such as in Bahir Dar, a strong alliance between the municipality and private enterprise is important so that appropriate solutions for improved financial sustainability of a SWM system can be sought and implemented. PMID:24246579

  6. LiDAR measurements of full scale wind turbine wake characteristics

    DEFF Research Database (Denmark)

    Hansen, Kurt Schaldemose; Larsen, Gunner Chr.

    2009-01-01

    Full scale wind speed measurements, recorded inside the wake of an operating 2MW/80m wind turbine,has been performed during the spring 2009, as part of the EU-TOPFARM project. Longitudinal wind speeds in wake cross sections are measured with a LiDAR system mounted in the rear of the nacelle. The experimental setup, the amount of data, preliminary analysis and limitations of using LIDAR measurements to identify the wake dynamics will be presented. Resolving the wake in the meandering frame of reference further allows for identification of the wake characteristics both in terms of wake deficit and wake turbulence.

  7. Rozmary dar?.

    Czech Academy of Sciences Publication Activity Database

    Bydžovská, Lenka

    Praha : Karolinum, 2012 - (Rakušanová, M.), s. 95-107 ISBN 978-80-246-2114-2 Institutional support: RVO:68378033 Keywords : Karel Teige * interwar avant-garde * Marcel Mauss * Jind?ich Štyrský * surrealist object * anthropomorfic book Subject RIV: AL - Art, Architecture, Cultural Heritage

  8. Evaluation of the dimensions of anger reactions-5 (DAR-5) scale in combat veterans with posttraumatic stress disorder.

    Science.gov (United States)

    Forbes, David; Alkemade, Nathan; Hopcraft, Dale; Hawthorne, Graeme; O'Halloran, Paul; Elhai, Jon D; McHugh, Tony; Bates, Glen; Novaco, Raymond W; Bryant, Richard; Lewis, Virginia

    2014-12-01

    After a traumatic event many people experience problems with anger which not only results in significant distress, but can also impede recovery. As such, there is value to include the assessment of anger in routine post-trauma screening procedures. The Dimensions of Anger Reactions-5 (DAR-5), as a concise measure of anger, was designed to meet such a need, its brevity minimizing the burden on client and practitioner. This study examined the psychometric properties of the DAR-5 with a sample of 163 male veterans diagnosed with Posttraumatic Stress Disorder. The DAR-5 demonstrated internal reliability (?=.86), along with convergent, concurrent and discriminant validity against a variety of established measures (e.g., HADS, PCL, STAXI). Support for the clinical cut-point score of 12 suggested by Forbes et al. (2014, Utility of the dimensions of anger reactions-5 (DAR-5) scale as a brief anger measure. Depression and Anxiety, 31, 166-173) was observed. The results support considering the DAR-5 as a preferred screening and assessment measure of problematic anger. PMID:25445072

  9. Development and mapping of DArT markers within the Festuca - Lolium complex

    DEFF Research Database (Denmark)

    Kopecký, David; Bartos, Jan

    2009-01-01

    Background Grasses are among the most important and widely cultivated plants on Earth. They provide high quality fodder for livestock, are used for turf and amenity purposes, and play a fundamental role in environment protection. Among cultivated grasses, species within the Festuca-Lolium complex predominate, especially in temperate regions. To facilitate high-throughput genome profiling and genetic mapping within the complex, we have developed a Diversity Arrays Technology (DArT) array for five grass species: F. pratensis, F. arundinacea, F. glaucescens, L. perenne and L. multiflorum. Results The DArTFest array contains 7680 probes derived from methyl-filtered genomic representations. In a first marker discovery experiment performed on 40 genotypes from each species (with the exception of F. glaucescens for which only 7 genotypes were used), we identified 3884 polymorphic markers. The number of DArT markers identified in every single genotype varied from 821 to 1852. To test the usefulness of DArTFest array for physical mapping, DArT markers were assigned to each of the seven chromosomes of F. pratensis using single chromosome substitution lines while recombinants of F. pratensis chromosome 3 were used to allocate the markers to seven chromosome bins. Conclusion The resources developed in this project will facilitate the development of genetic maps in Festuca and Lolium, the analysis on genetic diversity, and the monitoring of the genomic constitution of the Festuca × Lolium hybrids. They will also enable marker-assisted selection for multiple traits or for specific genome regions.

  10. ¿Es redundante la prueba de selectividad?.

    Directory of Open Access Journals (Sweden)

    Rúa Vieytes, Antonio.

    2003-01-01

    Full Text Available Como consecuencia de la futura reforma en las pruebas de acceso a la universidad española, en donde la principal novedad será la eliminación de la prueba de conjunto o selectividad, cabe reflexionar sobre tan controvertida prueba y preguntarnos si realmente dicha prueba ha servido para algo y su aplicación ha sido efectiva en el rendimiento del alumno una vez dentro de la universidad o, por el contrario, si se trata de una prueba redundante. A partir del expediente académico y de las notas de selectividad de una muestra de 2.500 alumnos durante siete años, se llevará a cabo un análisis econométrico del grado de explicación que estas notas tienen sobre la prueba de conjunto y se constatará si dicha prueba es efectiva o redundante.

  11. INNOVACIÓN: LO SOCIAL LE ES INMANENTE

    Directory of Open Access Journals (Sweden)

    GIOVANNI ARTURO L\\u00D3PEZ ISAZA

    2014-01-01

    Full Text Available En el marco del proyecto de investigación doctoral “Emprenderismo/educación, innovación/edu - cación, empleo/educación: lenguajes que atrapan sentidos”, este documento recoge aportes sobre la innovación social, indagando con una ventana de observación 2000-2013, en las bases de in - formación: Science Direct, Scopus, Springer Link, Google books, Google y otros actores ubicados en América y Europa. Dos conclusiones emergen de este documento: (i El hilo conductor de los discursos sobre innovación social, indica que ella es comprendida como proceso social y como fenómeno emergente, en el contexto de prácticas ciudadanas que enfrentan problemas sociales; pri - vilegiando intereses colectivos sobre individuales, fortaleciendo las capacidades de unos y de otros actores sociales. (ii La educación/comunicación abre, penetra y altera mentes; le otorga sentido a la innovación, como constructo y esperanza social; con la participación/conversación de ciudadanos plurales y totales, favorece fusiones creativas que configuran innovación social.

  12. El Pseudo-Hiepes es Bernardo Polo

    Directory of Open Access Journals (Sweden)

    Jordan, William B.

    2009-12-01

    Full Text Available Nearly fifteen years ago, the author proposed the name Pseudo-Hiepes to refer to a then anonymous painter whom certain Italian art historians had called the Master of the Lombard Fruit Bowl. At the time, he argued for an Aragonese origin in the later part of the century. A signed work has finally been discovered and is published here. The artist was indeed from Zaragoza, and his name is Bernardo Polo.

    Hace unos quince años, el autor propuso el apodo Pseudo-Hiepes para identificar al pintor anónimo a quien algunos entendidos italianos habían bautizado como Maestro del Frutero lombardo. En aquel entonces, argumentó que debía tratarse de un artista aragonés, de la segunda mitad de siglo. Por fin ha aparecido una obra firmada que se presenta aquí. Efectivamente, el artista era zaragozano y su nombre es Bernardo Polo.

  13. Study of TrES-3 Exoplanet

    Science.gov (United States)

    Vodniza, A. Q.; Rojas, M.; Reyes, K.

    2011-10-01

    The first amateur observation of an exoplanet was made from the Nyrola Observatory in September 16, 2000. (Marko Moilanen, Jalo Ojanperä, Jouni Sorvari, Aki Id and Arto Oksanen). The jovian-type planet orbits a star that is 153 light years far away, and was called HD209458b in Pegasus [1]. The equipment used by this Observatory was a 16 inches MEADE LX200, a ST7E CCD SBIG camera with a V photometric filter and an f/6.3 focal distance reducer. At the University of Nariño Observatory we have a similar equipment. The equipment we employed is: 14"LX200 GPS MEADE telescope and STL-1001 SBIG. The camera we used in our search is much more sensible than the one used by the Nyrola Observatory [2]. From the Astronomical Observatory at the University of Nariño-COLOMBIA, we begun a systematic search for exoplanets. We have already confirmed the transit of the exoplanet TrES-3. This exoplanet was discovered by O'Donovan and other investigators, and turns around the GSC 03089- 00929, with an orbital period of 1.30619 days (31.34856 hours) and inclination of 82.15 deg [3]. The TrES-3 is quite interesting because it has one of the smallest periods found on exoplanets. Jessie L. Christiansen, et.al. observed seven transits and they found that the duration of transit is 81.9+/-1.1 minutes and inclination of 81.99+/-0.30 deg [4], [5]. We have captured a lot of data to elaborate the lightcurves so we can estimate the physical parameters of the exoplanet.

  14. Geometrical parameters of E+S pairs

    International Nuclear Information System (INIS)

    Local environmental conditions (i.e., density and angular momentum properties of protogalactic clouds) are thought to be factors affecting the ultimate morphology of a galaxy. The existence of significant numbers of mixed morphology (E/SO+S) pairs of galaxies would represent a direct challenge to this idea. The authors have observed 22 pairs of mixed morphology galaxies selected from a catalog of Sulentic (1988: unpublished) based upon the ESO sky survey. The observed sample and relevant morphological and interaction characteristics are summarized in tabular form. The authors list the maximum values measured for the ellipticity and the a(4)/a shape parameter together with the total measured twisting along the profile beyond the seeing disk (they set an inner limit of 3 arcsed). An asterisk indicates objects in which a(4)/a is neither predominantly boxy nor disky. They found a large number of true mixed pairs with 13/22 E+S pairs in the present sample. The remaining objects include 5 disk pairs (composed of SO and S members) and 3 early-type pairs comprising E and SO members. They estimate that between 25 and 50 percent of the pairs in any complete sample will be of the E+S type. This suggests that 100 to 200 such pairs exist on the sky brighter than m sub pg = 16.0. They found no global evidence for a difference between E members of this sample and those in more general samples (e.g., Bender et al. 1989). In particular, they found that about 30 percent of the early-tyound that about 30 percent of the early-type galaxies cannot be classified either predominantly boxy or disky

  15. Arrangements for enhanced measurements of a large turbine near-wake using LiDAR from the nacelle

    International Nuclear Information System (INIS)

    New LiDAR techniques are being tested and developed to support the development of large offshore wind turbines. Our interest in this paper is concentrated in wake measurements; therefore, a pulsed standard LiDAR is adapted for fullscale wind field measurements from the nacelle of a large wind turbine. We show the conceptual framework for planned adaptations to a Windcube (registered) LiDAR for operation at the nacelle of a 5 MW wind turbine. The standard scanning mode is to be modified to properly obtain downstream and also upstream wind speeds. The wind field measurements are intended for verification of models for near-wake wind speed, wake meandering and new predictive control estrategies

  16. SVM-Based Classification of Segmented Airborne LiDAR Point Clouds in Urban Areas

    Directory of Open Access Journals (Sweden)

    Xiaogang Ning

    2013-07-01

    Full Text Available Object-based point cloud analysis (OBPA is useful for information extraction from airborne LiDAR point clouds. An object-based classification method is proposed for classifying the airborne LiDAR point clouds in urban areas herein. In the process of classification, the surface growing algorithm is employed to make clustering of the point clouds without outliers, thirteen features of the geometry, radiometry, topology and echo characteristics are calculated, a support vector machine (SVM is utilized to classify the segments, and connected component analysis for 3D point clouds is proposed to optimize the original classification results. Three datasets with different point densities and complexities are employed to test our method. Experiments suggest that the proposed method is capable of making a classification of the urban point clouds with the overall classification accuracy larger than 92.34% and the Kappa coefficient larger than 0.8638, and the classification accuracy is promoted with the increasing of the point density, which is meaningful for various types of applications.

  17. Method of flight planning for airborne LiDAR using genetic algorithms

    Science.gov (United States)

    Dashora, Ajay; Lohani, Bharat; Deb, Kalyanmoy

    2014-01-01

    Conventional methods of flight planning for airborne LiDAR are heuristic in nature and use an iterative trial and error approach. A new system-based approach of flight planning is presented in this paper. The presented approach automatically derives flight planning parameters by minimizing the cost of data acquisition, which is represented by flight duration. The flight duration, which is the sum of the strip time and turning time, is minimized using genetic algorithms under the constraints of mapping requirements, hardware limitations, user-defined preferences, and various other requirements. The proposed approach is first validated for conventionally known test cases of regular shapes (rectangular and triangular). Thereafter, it is implemented for an arbitrarily shaped simulated test site with two commercially available airborne LiDAR sensors. Statistical results are presented for the above. Further, flight planning is performed for two real test sites. The demonstrated approach not only produces optimal results, but also avoids the assumptions of conventional methods. Furthermore, the approach requires the least amount of human intervention and, thus, eliminates the subjectivity that is imposed by individual flight planners for determining the flight planning parameters. Encouraged by these results, the authors suggest that the proposed approach can be further developed to include all possible components of flight planning in a future work.

  18. Numerical modeling of the airflow around a forest edge using LiDAR-derived forest heigths

    DEFF Research Database (Denmark)

    Boudreault, Louis-Etienne; Dellwik, Ebba

    A 3D methodology to quantify the effect of forests on the mean wind flow field is presented. The methodology is based on the treatment of forest raw data of light detection and ranging (LiDAR) scans, and a computational fluid dynamics (CFD) method based on a Reynolds-averaged Navier-Stokes (RaNS) approach using the k?e turbulence model with a corresponding canopy model. The example site investigated is a forest edge located on the Falster island in Denmark, where a measurement campaign was conducted. The LiDAR scans are used in order to obtain the forest heights, which served as input to the numerical CFD model. A sensitivity analysis with regards to the resolution of the structured forest height grid obtained from the implemented digital elevation model (DEM) was carried out. CFD calculations were conducted with the forest height grid taken as input and the complete methodology results are finally briefly compared to the wind measurements of the site with regards to the calculated wind field prediction accuracy.

  19. Quantifying landscape change in an arctic coastal lowland using repeat airborne LiDAR

    Science.gov (United States)

    Jones, Benjamin M.; Stoker, Jason M.; Gibbs, Ann E.; Grosse, Guido; Romanovsky, Vladimir E.; Douglas, Thomas A.; Kinsman, Nichole E.M.; Richmond, Bruce M.

    2013-01-01

    Increases in air, permafrost, and sea surface temperature, loss of sea ice, the potential for increased wave energy, and higher river discharge may all be interacting to escalate erosion of arctic coastal lowland landscapes. Here we use airborne light detection and ranging (LiDAR) data acquired in 2006 and 2010 to detect landscape change in a 100 km2 study area on the Beaufort Sea coastal plain of northern Alaska. We detected statistically significant change (99% confidence interval), defined as contiguous areas (>10 m2) that had changed in height by at least 0.55 m, in 0.3% of the study region. Erosional features indicative of ice-rich permafrost degradation were associated with ice-bonded coastal, river, and lake bluffs, frost mounds, ice wedges, and thermo-erosional gullies. These features accounted for about half of the area where vertical change was detected. Inferred thermo-denudation and thermo-abrasion of coastal and river bluffs likely accounted for the dominant permafrost-related degradational processes with respect to area (42%) and volume (51%). More than 300 thermokarst pits significantly subsided during the study period, likely as a result of storm surge flooding of low-lying tundra (repeat airborne LiDAR can be used to detect landscape change in arctic coastal lowland regions at large spatial scales over sub-decadal time periods.

  20. Optical turbulence profiling with SloDAR in the Canadian High Arctic

    Science.gov (United States)

    Maire, Jérôme; Mieda, Etsuko; Steinbring, Eric; Murowinski, Richard; Graham, James R.; Carlberg, Raymond; Wright, Shelley A.; Law, Nicholas M.; Sivanandam, Suresh

    2014-07-01

    The Earth's polar regions offer unique advantages for ground-based astronomical observations with its cold and dry climate, long periods of darkness, and the potential for exquisite image quality. We present preliminary results from a site-testing campaign during nighttime from October to November 2012 at the Polar Environment Atmospheric Research Laboratory (PEARL), on a 610-m high ridge near the Eureka weatherstation on Ellesmere Island, Canada. A Shack-Hartmann wavefront sensor was employed, using the Slope Detection and Ranging (SloDAR) method. This instrument (Mieda et al, this conference) was designed to measure the altitude, strength and variability of atmospheric turbulence, in particular for operation under Arctic conditions. First SloDAR optical turbulence profiles above PEARL show roughly half of the optical turbulence confined to the boundary layer, below about 1 km, with the majority of the remainder in one or two thin layers between 2 km and 5 km, or above. The median seeing during this campaign was measured to be 0.65 arcsec.

  1. Genetic diversity of carotenoid-rich bananas evaluated by Diversity Arrays Technology (DArT)

    Scientific Electronic Library Online (English)

    Edson P., Amorim; Alberto D., Vilarinhos; Kelly O., Cohen; Vanusia B.O., Amorim; Janay A. dos, Santos-Serejo; Sebastião Oliveira e, Silva; Kátia N., Pestana; Vânia J. dos, Santos; Norma S., Paes; Damares C., Monte; Ronaldo V. dos, Reis.

    Full Text Available The aim of this work was to evaluate the carotenoid content and genetic variability of banana accessions from the Musa germplasm collection held at Embrapa Cassava and Tropical Fruits, Brazil. Forty-two samples were analyzed, including 21 diploids, 19 triploids and two tetraploids. The carotenoid co [...] ntent was analyzed spectrophotometrically and genetic variability was estimated using 653 DArT markers. The average carotenoid content was 4.73 µg.g-1, and ranged from 1.06 µg.g-1 for the triploid Nanica (Cavendish group) to 19.24 µg.g-1 for the triploid Saney. The diploids Modok Gier and NBA-14 and the triploid Saney had a carotenoid content that was, respectively, 7-fold, 6-fold and 9-fold greater than that of cultivars from the Cavendish group (2.19 µg.g-1). The mean similarity among the 42 accessions was 0.63 (range: 0.24 to 1.00). DArT analysis revealed extensive genetic variability in accessions from the Embrapa Musa germplasm bank.

  2. Retrieval of Forest Aboveground Biomass and Stem Volume with Airborne Scanning LiDAR

    Directory of Open Access Journals (Sweden)

    Petteri Alho

    2013-05-01

    Full Text Available Airborne scanning LiDAR is a promising technique for efficient and accuratebiomass mapping due to its capacity for direct measurement of the three-dimensionalstructure of vegetation. A combination of individual tree detection (ITD and an area-basedapproach (ABA introduced in Vastaranta et al. [1] to map forest aboveground biomass(AGB and stem volume (VOL was investigated. The main objective of this study was totest the usability and accuracy of LiDAR in biomass mapping. The nearest neighbourmethod was used in the ABA imputations and the accuracy of the biomass estimation wasevaluated in the Finland, where single tree-level biomass models are available. The relativeroot-mean-squared errors (RMSEs in plot-level AGB and VOL imputation were 24.9%and 26.4% when field measurements were used in training the ABA. When ITDmeasurements were used in training, the respective accuracies ranged between 28.5%–34.9%and 29.2%–34.0%. Overall, the results show that accurate plot-level AGB estimates can beachieved with the ABA. The reduction of bias in ABA estimates in AGB and VOL wasencouraging when visually corrected ITD (ITDvisual was used in training. We conclude that itis not feasible to use ITDvisual in wall-to-wall forest biomass inventory, but it could provide acost-efficient application for acquiring training data for ABA in forest biomass mapping.

  3. A new method for building roof segmentation from airborne LiDAR point cloud data

    Science.gov (United States)

    Kong, Deming; Xu, Lijun; Li, Xiaolu

    2013-09-01

    A new method based on the combination of two kinds of clustering algorithms for building roof segmentation from airborne LiDAR (light detection and ranging) point cloud data is proposed. The K-plane algorithm is introduced to classify the laser footprints that cannot be correctly classified by the traditional K-means algorithm. High-precision classification can be obtained by combining the two aforementioned clustering algorithms. Furthermore, to improve the performance of the new segmentation method, a new initialization method is proposed to acquire the number and coordinates of the initial cluster centers for the K-means algorithm. In the proposed initialization method, the geometrical planes of a building roof are estimated from the elevation image of the building roof by using the mathematical morphology and Hough transform techniques. By calculating the number and normal vectors of the estimated geometrical planes, the number and coordinates of the initial cluster centers for the K-means algorithm are obtained. With the aid of the proposed initialization and segmentation methods, the point cloud of the building roof can be rapidly and appropriately classified. The proposed methods are validated by using both simulated and real LiDAR data.

  4. Genetic diversity of carotenoid-rich bananas evaluated by Diversity Arrays Technology (DArT

    Directory of Open Access Journals (Sweden)

    Edson P. Amorim

    2009-01-01

    Full Text Available The aim of this work was to evaluate the carotenoid content and genetic variability of banana accessions from the Musa germplasm collection held at Embrapa Cassava and Tropical Fruits, Brazil. Forty-two samples were analyzed, including 21 diploids, 19 triploids and two tetraploids. The carotenoid content was analyzed spectrophotometrically and genetic variability was estimated using 653 DArT markers. The average carotenoid content was 4.73 µg.g-1, and ranged from 1.06 µg.g-1 for the triploid Nanica (Cavendish group to 19.24 µg.g-1 for the triploid Saney. The diploids Modok Gier and NBA-14 and the triploid Saney had a carotenoid content that was, respectively, 7-fold, 6-fold and 9-fold greater than that of cultivars from the Cavendish group (2.19 µg.g-1. The mean similarity among the 42 accessions was 0.63 (range: 0.24 to 1.00. DArT analysis revealed extensive genetic variability in accessions from the Embrapa Musa germplasm bank.

  5. Processing Large LiDAR datasets for Forest Canopy Metrics Using 64-bit GRASS GIS (Invited)

    Science.gov (United States)

    Newcomb, D.; Mitasova, H.

    2009-12-01

    The flooding impacts of tropical storm events in 1999 inspired the statewide collection of LiDAR data in the State of North Carolina, USA, in three phases between 2001 and 2006, for the purpose of floodplain mapping. This data collection effort generated more than 800 GB of multiple return LiDAR data. Using native 64-bit GRASS on 64-bit Centos Linux, forest canopy heights and other structural metrics were generated on a 18.2 m (60 foot) grid for the entire State of North Carolina from ASCII x,y,z datasets ranging in size from 9GB to 379 GB using binning techniques to calculate max, min, and standard deviation statistical measures for each grid cell using tools available in GRASS 6.3-6.4 to derive initial canopy heights. Data processing time for each file ranged from less than 1 hour hr ( 9 GB) to 15 hrs (379 GB). Data from the 6.1m (20ft) elevation grid generated for the floodplain mapping project was analyzed using neighborhood analysis to correct for the effects of land surface change within each 18.2m (60 ft) cell. Canopy heights up to 76.2m (249 ft) were calculated and the raster data sets were aggregated to a grid with 17237 Rows and 45102 columns . Histograms of canopy height data were derived from buffered known locations of bird nesting habitat for birds with differing canopy requirements.

  6. LiDAR-Assisted identification of an active fault near Truckee, California

    Science.gov (United States)

    Hunter, L.E.; Howle, J.F.; Rose, R.S.; Bawden, G.W.

    2011-01-01

    We use high-resolution (1.5-2.4 points/m2) bare-earth airborne Light Detection and Ranging (LiDAR) imagery to identify, map, constrain, and visualize fault-related geomorphology in densely vegetated terrain surrounding Martis Creek Dam near Truckee, California. Bare-earth LiDAR imagery reveals a previously unrecognized and apparently youthful right-lateral strike-slip fault that exhibits laterally continuous tectonic geomorphic features over a 35-km-long zone. If these interpretations are correct, the fault, herein named the Polaris fault, may represent a significant seismic hazard to the greater Truckee-Lake Tahoe and Reno-Carson City regions. Three-dimensional modeling of an offset late Quaternary terrace riser indicates a minimum tectonic slip rate of 0.4 ?? 0.1 mm/yr.Mapped fault patterns are fairly typical of regional patterns elsewhere in the northern Walker Lane and are in strong coherence with moderate magnitude historical seismicity of the immediate area, as well as the current regional stress regime. Based on a range of surface-rupture lengths and depths to the base of the seismogenic zone, we estimate a maximum earthquake magnitude (M) for the Polaris fault to be between 6.4 and 6.9.

  7. ¿Qué es la CIE y por qué es importante en la psicología?

    Directory of Open Access Journals (Sweden)

    Geoffrey M. Reed

    2012-01-01

    Full Text Available La Clasificación Internacional de las Enfermedades (CIE de la Organización Mundial de Salud (OMS es muy poco conocida en el ámbito de la psicología en España, y existe la falsa percepción de que su importancia es escasa en el campo de la salud mental. El propósito de este artículo es familiarizar a los psicólogos y otros profesionales en salud mental con el sistema de clasificación CIE, algo especialmente relevante al encontrarse actualmente en proceso de revisión. La OMS está haciendo un gran esfuerzo para crear una clasificación de trastornos mentales global, multicultural y multidisciplinar, centrándose en mejorar su utilidad clínica. Además, en la actual revisión de la CIE, la OMS ha adoptado el español como segunda lengua de trabajo, lo que da una gran oportunidad a los profesionales de la salud mental de España y otros países hispanohablantes de implicarse activamente en el desarrollo de la próxima versión de la clasificación. Es importante que los psicólogos de países hispanohablantes conozcan la CIE y entiendan los grandes beneficios que pueden aportarles su conocimiento y utilización para integrarse plenamente como profesión sanitaria oficial, así como para equipararse en la práctica de la psicología al resto de Europa y de todo el mundo en términos de diagnóstico y clasificación de los trastornos mentales.

  8. Integrated LiDAR, geophysical and geotechnical monitoring of an active inland landslide, UK

    Science.gov (United States)

    Chambers, Jonathan; Hobbs, Peter; Pennington, Catherine; Jones, Lee; Dixon, Neil; Spriggs, Mathew; Haslam, Edward; Meldrum, Philip; Foster, Claire; Jenkins, Gareth

    2010-05-01

    The British Geological Survey have established a long-term landslide field observatory with Loughborough University in the north of England. At this site an integrated approach of surface and subsurface geophysics, terrestrial and aerial LiDAR, GPS surveys, borehole inclinometers and surface tiltmeters combined with conventional ground investigation methods is being used to monitor the active landslide at Hollin Hill, North Yorkshire. The combination of repeated terrestrial LiDAR surveys and continuous subsurface geophysics allows the monitoring of large scale changes in the morphology of the slope in conjunction with subsurface movements. The Hollin Hill landslide has been surveyed with both aerial and terrestrial LiDAR surveys providing a unique opportunity to appraise the relative merits of the different technologies and their application in monitoring an active natural landslide site under typical UK conditions. High resolution repeat terrestrial LiDAR surveys and field differential GPS measurements are used to provide an accurate baseline geomorphological map data on the rate of movement and relative areas of activity on the landslide. Borehole inclinometers and novel down-hole acoustic emission slope displacement rate sensors attached to active waveguides allow depth of movement to be determined. To understand the subsurface processes time lapse Electrical Resistivity Tomography (ERT) and Self Potential (SP) have been utilised in order to characterise the subsurface structure, monitor hydrogeological changes (i.e. water table, moisture content, seepage pathways) and investigate the link between these changes and the movement of the landslide. These geophysical techniques provide spatial/volumetric information at a site scale, whilst being sensitive to hydraulic changes in the subsurface and augmenting the study of movement of the landslide in three dimensions. The aim of this work is to characterise the subsurface structure of the landslide and reveal the hydraulic precursors to movement which can eventually be used to develop a true 4-D landslide monitoring system. The landslide is being remotely monitored through the installation of an automated time-lapse electrical resistivity tomography (ALERT) system which is permanently installed on the site. The ALERT system uses wireless telemetry (in this case GPRS) to communicate with a PC. Once installed and configured, the system operates autonomously without manual intervention. Environmental and geotechnical sensors have also been installed to monitor rainfall, ground movement and pore pressure changes within the landslide. Early results from the geophysical monitoring have allowed an accurate subsurface geometry of the landslide to be defined coupled with a highly accurate surface model from the LiDAR data. The combined systems are now capable of relating ground water conditions and ground deformations, each with at least two independent methods, and relate these to changing environmental factors at Hollin Hill and hence contribute to our knowledge of the changing climate.

  9. Modelling stand biomass fractions in Galician Eucalyptus globulus plantations by use of different LiDAR pulse densities

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Ferreiro, E.; Miranda, D.; Barreiro-Fernandez, L.; Bujan, S.; Garcia-Gutierrez, J.; Dieguez-Aranda, U.

    2013-07-01

    Aims of study: To evaluate the potential use of canopy height and intensity distributions, determined by airborne LiDAR, for the estimation of crown, stem and aboveground biomass fractions. To assess the effects of a reduction in LiDAR pulse densities on model precision. Area of study: The study area is located in Galicia, NW Spain. The forests are representative of Eucalyptus globulus stands in NW Spain, characterized by low-intensity silvicultural treatments and by the presence of tall shrub. Material and methods: Linear, multiplicative power and exponential models were used to establish empirical relationships between field measurements and LiDAR metrics. A random selection of LiDAR returns and a comparison of the prediction errors by LiDAR pulse density factor were performed to study a possible loss of fit in these models. Main results: Models showed similar goodness-of-fit statistics to those reported in the international literature. R2 ranged from 0.52 to 0.75 for stand crown biomass, from 0.64 to 0.87 for stand stem biomass, and from 0.63 to 0.86 for stand aboveground biomass. The RMSE/MEAN 100 of the set of fitted models ranged from 17.4% to 28.4%. Models precision was essentially maintained when 87.5% of the original point cloud was reduced, i.e. a reduction from 4 pulses m{sup 2} to 0.5 pulses m{sup 2}. Research highlights: Considering the results of this study, the low-density LiDAR data that are released by the Spanish National Geographic Institute will be an excellent source of information for reducing the cost of forest inventories. (Author)

  10. Using LiDAR to Estimate Total Aboveground Biomass of Redwood Stands in the Jackson Demonstration State Forest, Mendocino, California

    Science.gov (United States)

    Rao, M.; Vuong, H.

    2013-12-01

    The overall objective of this study is to develop a method for estimating total aboveground biomass of redwood stands in Jackson Demonstration State Forest, Mendocino, California using airborne LiDAR data. LiDAR data owing to its vertical and horizontal accuracy are increasingly being used to characterize landscape features including ground surface elevation and canopy height. These LiDAR-derived metrics involving structural signatures at higher precision and accuracy can help better understand ecological processes at various spatial scales. Our study is focused on two major species of the forest: redwood (Sequoia semperirens [D.Don] Engl.) and Douglas-fir (Pseudotsuga mensiezii [Mirb.] Franco). Specifically, the objectives included linear regression models fitting tree diameter at breast height (dbh) to LiDAR derived height for each species. From 23 random points on the study area, field measurement (dbh and tree coordinate) were collected for more than 500 trees of Redwood and Douglas-fir over 0.2 ha- plots. The USFS-FUSION application software along with its LiDAR Data Viewer (LDV) were used to to extract Canopy Height Model (CHM) from which tree heights would be derived. Based on the LiDAR derived height and ground based dbh, a linear regression model was developed to predict dbh. The predicted dbh was used to estimate the biomass at the single tree level using Jenkin's formula (Jenkin et al 2003). The linear regression models were able to explain 65% of the variability associated with Redwood's dbh and 80% of that associated with Douglas-fir's dbh.

  11. Detection of large above-ground biomass variability in lowland forest ecosystems by airborne LiDAR

    Directory of Open Access Journals (Sweden)

    J. Jubanski

    2013-06-01

    Full Text Available Quantification of tropical forest above-ground biomass (AGB over large areas as input for Reduced Emissions from Deforestation and forest Degradation (REDD+ projects and climate change models is challenging. This is the first study which attempts to estimate AGB and its variability across large areas of tropical lowland forests in Central Kalimantan (Indonesia through correlating airborne light detection and ranging (LiDAR to forest inventory data. Two LiDAR height metrics were analysed, and regression models could be improved through the use of LiDAR point densities as input (R2 = 0.88; n = 52. Surveying with a LiDAR point density per square metre of about 4 resulted in the best cost / benefit ratio. We estimated AGB for 600 km of LiDAR tracks and showed that there exists a considerable variability of up to 140% within the same forest type due to varying environmental conditions. Impact from logging operations and the associated AGB losses dating back more than 10 yr could be assessed by LiDAR but not by multispectral satellite imagery. Comparison with a Landsat classification for a 1 million ha study area where AGB values were based on site-specific field inventory data, regional literature estimates, and default values by the Intergovernmental Panel on Climate Change (IPCC showed an overestimation of 43%, 102%, and 137%, respectively. The results show that AGB overestimation may lead to wrong greenhouse gas (GHG emission estimates due to deforestation in climate models. For REDD+ projects this leads to inaccurate carbon stock estimates and consequently to significantly wrong REDD+ based compensation payments.

  12. Coronary heart disease risk factors in sub-Saharan Africa: studies in Tanzanian adolescents.

    OpenAIRE

    Kitange, H. M.; Swai, A. B.; Masuki, G.; Kilima, P. M.; Alberti, K. G.; Mclarty, D. G.

    1993-01-01

    STUDY OBJECTIVE--To assess the level of cardiovascular risk factors in young people in sub-Saharan Africa living in rural and urban settings. DESIGN--Cross sectional survey of the population aged 15 to 19 years. SETTING--Eight rural Tanzanian villages in three regions, and two districts in Dar es Salaam. PARTICIPANTS--664 males and 803 females in rural villages and 85 males and 121 females in the city. Response rates for total population were 74% to 94% in the rural areas and 60% in the city....

  13. HIV SEROPREVALENCE IN A SAMPLE OF TANZANIAN INTRAVENOUS DRUG USERS

    OpenAIRE

    Williams, Mark L.; Mccurdy, Sheryl A.; Bowen, Anne M.; Kilonzo, Gad P.; Atkinson, John S.; Ross, Michael W.; Leshabari, M. T.

    2009-01-01

    Injection drug use has recently emerged in sub-Saharan Africa. The purpose of this study was to assess the factors associated with increased risk of testing HIV-positive in a sample of injection drug users (IDUs) in Dar es Salaam, Tanzania. Participants were recruited by a trained outreach worker or were referred by IDUs who had completed the study. Blood specimens and self-reported socioeconomic and behavioral data were collected from 315 male and 219 female IDUs. Data were analyzed using un...

  14. Self-initiation of antiretroviral therapy in the developing world: the involvement of private pharmacies in an HIV program

    Directory of Open Access Journals (Sweden)

    Minzi OM

    2012-03-01

    Full Text Available Omary Mashiku Minzi1, Deus Buma2, Godeliver A Kagashe3 1Unit of Pharmacology and Therapeutics, School of Pharmacy, Muhimbili University of Health and Allied Sciences, Dar Es Salaam, Tanzania; 2Department of Pharmaceutics, School of Pharmacy, Muhimbili University of Health and Allied Sciences, Dar Es Salaam, Tanzania; 3Department of Pharmacy, Muhimbili National Hospital, Dar Es Salaam, TanzaniaBackground: Self-initiation to antiretroviral treatment (ART exposes the patient to the risk of drug toxicity, poor adherence to treatment, and escalates the development of drug resistance.Objectives: To determine the sources of antiretroviral (ARV drugs by unregistered human immunodeficiency virus (HIV-infected patients and the extent of ARV self-medication.Methods: Simulated clients were used to investigate availability and ARV dispensing practice in the private pharmacies in Dar Es Salaam, Tanzania. A total of 480 HIV-infected patients qualifying to start ART were interviewed to find out their previous use of ARV drugs prior to visiting the HIV clinics. Venous blood (2 mL was collected from each patient who indicated not to have used ARVs in the past (n = 450. Blood samples were analyzed for the presence and levels of nevirapine (NVP.Results: Only 5.1% (23/451 of pharmacies were found stocking ARVs drugs, among which 4.0% were retail. Drug dispensers in nearly all (15/18 retail pharmacies which stocked ARVs were willing to sell ARVs without prescription. Out of 450 enrolled patients, only 2.7% (12 stated that they had been receiving ARV drugs from HIV clinics but interrupted the ART treatment due to various reasons. From 450 patients, only 10% had quantifiable NVP concentrations in the blood, despite stating in an interview that they had not recently used ARVs.Conclusion: Prior use of ARV drugs outside HIV clinics was rare among patients attending those centers. However, the results show that some patients could access and use ARV drugs from private pharmacies without undergoing ART eligibility assessment in HIV clinics.Keywords: ART naïve patients, antiretroviral drugs, dispensing practices

  15. Beyond the Utenzi: narrative poems by Theobald Mvungi

    OpenAIRE

    Bertoncini-zu?bkova?, Elena

    2012-01-01

    Some time ago I came across a tiny collection of poems called Chungu tamu by Theobald Mvungi. The author was born in Mwanga province (Kilimanjaro) probably in the Fifties, as he graduated from the University of Dar es Salaam in 1975 and gained his M.Ed. degree in Nigeria (Ibadan) in 1978. He published his first collection of poems, Raha karaha, in 1982 and his third one, Mashairiya Chekacheka, in 1995. All Mwangi`s poems deal with social problems, but only those of the second collection are f...

  16. Assessing vulnerability of urban African communities using multi-dimensional indicators selected by stakeholders

    DEFF Research Database (Denmark)

    Karlsson Nyed, Patrik; Herslund, Lise Byskov

    East African cities are in the process of assessing their vulnerabilities to climate change, but face difficulties in capturing the complexity of the various facets of vulnerability. This holistic approach, captures four different dimensions of vulnerability to flooding - Assets, Institutions, Attitudes and the Physical environment, with Dar es Salaam, Tanzania, as a case city. The methodology is actively involving the expertise of the stakeholders, and uses GIS to analyze and compile the data. The final output is presented as a comprehensible map, delineating the varying vulnerability to flooding across the city, at the finest administrative level.

  17. Psychometric properties and the prevalence, intensity and causes of oral impacts on daily performance (OIDP) in a population of older Tanzanians

    OpenAIRE

    Ia, Kida; An, A?strøm; Gv, Strand; Jr, Masalu; Tsakos G

    2006-01-01

    Abstract Background The objective was to study whether a Kiswahili version of the OIDP (Oral Impacts on Daily Performance) inventory was valid and reliable for use in a population of older adults in urban and rural areas of Tanzania; and to assess the area specific prevalence, intensity and perceived causes of OIDP. Method A cross-sectional survey was conducted in Pwani region and in Dar es Salaam in 2004/2005. A two-stage stratified cluster sample design was utilized. Information became ava...

  18. Analysis of Ozone (O3) and Erythemal UV (EUV) measured by TOMS in the equatorial African belt

    Scientific Electronic Library Online (English)

    Taddeo, Ssenyonga; Jakob J, Stamnes; Arne, Dahlback; Andreas, Steigen; Willy, Okullo; Øyvind, Frette.

    2010-02-01

    Full Text Available SciELO South Africa | Language: English Abstract in english We presented time series of total ozone column amounts (TOCAs) and erythemal UV (EUV) doses derived from measurements by TOMS (Total Ozone Mapping Spectrometer) instruments on board the Nimbus-7 (N7) and the Earth Probe (EP) satellites for three locations within the equatorial African belt for the p [...] eriod 1979 to 2000. The locations were Dar-es-Salaam (6.8º S, 39.26º E) in Tanzania, Kampala (0.19º N, 32.34º E) in Uganda, and Serrekunda (13.28º N, 16.34º W) in Gambia. Equatorial Africa has high levels of UV radiation, and because ozone shields UV radiation from reaching the Earth's surface, there is a need to monitor TOCAs and EUV doses. In this paper we investigated the trend of TOCAs and EUV doses, the effects of annual and solar cycles on TOCAs, as well as the link between lightning and ozone production in the equatorial African belt. We also compared clear-sky simulated EUV doses with the corresponding EUV doses derived from TOMS measurements. The TOCAs were found to vary in the ranges 243 DU - 289 DU, 231 DU - 286 DU, and 236 DU - 296 DU, with mean values of 266.9 DU, 260.9 DU, and 267.8 DU for Dar-es-Salaam, Kampala and Serrekunda, respectively. Daily TOCA time series indicated that Kampala had the lowest TOCA values, which we attributed to the altitude effect. There were two annual ozone peaks in Dar-es-Salaam and Kampala, and one annual ozone peak in Serrekunda. The yearly TOCA averages showed an oscillation within a five-year period. We also found that the EUV doses were stable at all three locations for the period 1979-2000, and that Kampala and Dar-es-Salaam were mostly cloudy throughout the year, whereas Serrekunda was mostly free from clouds. It was also found that clouds were among the major factors determining the level of EUV reaching the Earth´s surface. Finally, we noted that during rainy seasons, horizontal advection effects augmented by lightning activity may be responsible for enhanced ozone production in the tropics.

  19. Social context of disclosing HIV test results in Tanzania.

    Science.gov (United States)

    Lugalla, Joe; Yoder, Stanley; Sigalla, Huruma; Madihi, Charles

    2012-01-01

    This study sought to understand how individuals reveal their HIV test results to others and the ways in which social relations affect the disclosure process. The data were collected through open-ended interviews administered in Swahili to informants who had just been tested for HIV and to those who were living with HIV in Dar es Salaam and Iringa regions. Analysis shows that social relations influence the decisions individuals make about disclosure. Most people preferred to reveal their HIV status to close family members. Most also mentioned the fear of being rejected and discriminated against as major reasons for not disclosing their test results to others. PMID:21936654

  20. Three-dimensional building roof boundary extraction using high-resolution aerial image and LiDAR data

    Science.gov (United States)

    Dal Poz, A. P.; Fazan, Antonio J.

    2014-10-01

    This paper presents a semiautomatic method for rectilinear building roof boundary extraction, based on the integration of high-resolution aerial image and LiDAR (Light Detection and Ranging) data. The proposed method is formulated as an optimization problem, in which a snakes-based objective function is developed to represent the building roof boundaries in an object-space coordinate system. Three-dimensional polylines representing building roof boundaries are obtained by optimizing the objective function using the dynamic programming optimization technique. The results of our experiments showed that the proposed method satisfactorily performed the task of extracting different building roof boundaries from aerial image and LiDAR data.

  1. Object-Based Integration of Photogrammetric and LiDAR Data for Automated Generation of Complex Polyhedral Building Models

    Directory of Open Access Journals (Sweden)

    Ayman Habib

    2009-07-01

    Full Text Available This research is concerned with a methodology for automated generation of polyhedral building models for complex structures, whose rooftops are bounded by straight lines. The process starts by utilizing LiDAR data for building hypothesis generation and derivation of individual planar patches constituting building rooftops. Initial boundaries of these patches are then refined through the integration of LiDAR and photogrammetric data and hierarchical processing of the planar patches. Building models for complex structures are finally produced using the refined boundaries. The performance of the developed methodology is evaluated through qualitative and quantitative analysis of the generated building models from real data.

  2. Quantification of LiDAR measurement uncertainty through propagation of errors due to sensor sub-systems and terrain morphology

    Science.gov (United States)

    Goulden, T.; Hopkinson, C.

    2013-12-01

    The quantification of LiDAR sensor measurement uncertainty is important for evaluating the quality of derived DEM products, compiling risk assessment of management decisions based from LiDAR information, and enhancing LiDAR mission planning capabilities. Current quality assurance estimates of LiDAR measurement uncertainty are limited to post-survey empirical assessments or vendor estimates from commercial literature. Empirical evidence can provide valuable information for the performance of the sensor in validated areas; however, it cannot characterize the spatial distribution of measurement uncertainty throughout the extensive coverage of typical LiDAR surveys. Vendor advertised error estimates are often restricted to strict and optimal survey conditions, resulting in idealized values. Numerical modeling of individual pulse uncertainty provides an alternative method for estimating LiDAR measurement uncertainty. LiDAR measurement uncertainty is theoretically assumed to fall into three distinct categories, 1) sensor sub-system errors, 2) terrain influences, and 3) vegetative influences. This research details the procedures for numerical modeling of measurement uncertainty from the sensor sub-system (GPS, IMU, laser scanner, laser ranger) and terrain influences. Results show that errors tend to increase as the laser scan angle, altitude or laser beam incidence angle increase. An experimental survey over a flat and paved runway site, performed with an Optech ALTM 3100 sensor, showed an increase in modeled vertical errors of 5 cm, at a nadir scan orientation, to 8 cm at scan edges; for an aircraft altitude of 1200 m and half scan angle of 15°. In a survey with the same sensor, at a highly sloped glacial basin site absent of vegetation, modeled vertical errors reached over 2 m. Validation of error models within the glacial environment, over three separate flight lines, respectively showed 100%, 85%, and 75% of elevation residuals fell below error predictions. Future work in LiDAR sensor measurement uncertainty must focus on the development of vegetative error models to create more robust error prediction algorithms. To achieve this objective, comprehensive empirical exploratory analysis is recommended to relate vegetative parameters to observed errors.

  3. Mapping Above- and Below-Ground Biomass Components in Subtropical Forests Using Small-Footprint LiDAR

    OpenAIRE

    Lin Cao; Coops, Nicholas C.; John Innes; Jinsong Dai; Guanghui She

    2014-01-01

    In order to better assess the spatial variability in subtropical forest biomass, the goal of our study was to use small-footprint, discrete-return Light Detection and Ranging (LiDAR) data to accurately estimate and map above- and below-ground biomass components of subtropical forests. Foliage, branch, trunk, root, above-ground and total biomass of 53 plots (30 × 30 m) were modeled using a range of LiDAR-derived metrics, with individual models built for each of the three dominant forest type...

  4. Knowledge-Based Modeling of Buildings in Dense Urban Areas by Combining Airborne LiDAR Data and Aerial Images

    OpenAIRE

    Junichi Susaki

    2013-01-01

    In this paper, a knowledge-based algorithm is proposed for automatically generating three-dimensional (3D) building models in dense urban areas by using airborne light detection and ranging (LiDAR) data and aerial images. Automatic 3D building modeling using LiDAR is challenging in dense urban areas, in which houses are typically located close to each other and their heights are similar. This makes it difficult to separate point clouds into individual buildings. A combination of airborne LiDA...

  5. Monitoring Depth of Shallow Atmospheric Boundary Layer to Complement LiDAR Measurements Affected by Partial Overlap

    OpenAIRE

    Sandip Pal

    2014-01-01

    There is compelling evidence that the incomplete laser beam receiver field-of-view overlap (i.e., partial overlap) of ground-based vertically-pointing aerosol LiDAR restricts the observational range for detecting aerosol layer boundaries to a certain height above the LiDAR. This height varies from one to few hundreds of meters, depending on the transceiver geometry. The range, or height of full overlap, is defined as the minimum distance at which the laser beam is completely imaged onto the ...

  6. ES FUNDAMENTAL LA HERMENÉUTICA / Is Hermeneutics Fundamental

    Scientific Electronic Library Online (English)

    EMMANUEL, FALQUE.

    2013-08-01

    Full Text Available RESUMEN Se interroga el fundamento de la hermenéutica del texto y lo que significa retomarla a la letra en filosofía y en teología. Una hermenéutica es fundamental si se afinca en un modo de existencia adecuado a su propósito, de modo que se diferencie mejor y sea identificada claramente. La hermené [...] utica protestante del sentido del texto y la hermenéutica judía del cuerpo de la letra serán sustituidas aquí por una hermenéutica católica del texto del cuerpo, en una tentativa al menos programática. Abstract in english ABSTRACT The article inquires into the basis of textual hermeneutics and what it means to apply it literally in philosophy and theology. Hermeneutics is fundamental if it is grounded in a mode of existence that is adequate to its purpose, so that it is better differentiated and clearly identified. T [...] he Protestant hermeneutics of the meaning of the text and the Jewish hermeneutics of the body of the letter are here replaced by a Catholic hermeneutics of the text of the body, in an attempt that is at least programmatic.

  7. Fusion of LiDAR and aerial imagery for the estimation of downed tree volume using Support Vector Machines classification and region based object fitting

    Science.gov (United States)

    Selvarajan, Sowmya

    The study classifies 3D small footprint full waveform digitized LiDAR fused with aerial imagery to downed trees using Support Vector Machines (SVM) algorithm. Using small footprint waveform LiDAR, airborne LiDAR systems can provide better canopy penetration and very high spatial resolution. The small footprint waveform scanner system Riegl LMS-Q680 is addition with an UltraCamX aerial camera are used to measure and map downed trees in a forest. The various data preprocessing steps helped in the identification of ground points from the dense LiDAR dataset and segment the LiDAR data to help reduce the complexity of the algorithm. The haze filtering process helped to differentiate the spectral signatures of the various classes within the aerial image. Such processes, helped to better select the features from both sensor data. The six features: LiDAR height, LiDAR intensity, LiDAR echo, and three image intensities are utilized. To do so, LiDAR derived, aerial image derived and fused LiDAR-aerial image derived features are used to organize the data for the SVM hypothesis formulation. Several variations of the SVM algorithm with different kernels and soft margin parameter C are experimented. The algorithm is implemented to classify downed trees over a pine trees zone. The LiDAR derived features provided an overall accuracy of 98% of downed trees but with no classification error of 86%. The image derived features provided an overall accuracy of 65% and fusion derived features resulted in an overall accuracy of 88%. The results are observed to be stable and robust. The SVM accuracies were accompanied by high false alarm rates, with the LiDAR classification producing 58.45%, image classification producing 95.74% and finally the fused classification producing 93% false alarm rates The Canny edge correction filter helped control the LiDAR false alarm to 35.99%, image false alarm to 48.56% and fused false alarm to 37.69% The implemented classifiers provided a powerful tool for downed tree classification with fused LiDAR and aerial image. The classified tree pixels are utilized in the object based region fitting technique to compute the diameter and height of the downed trees and the volume of the trees are estimated. (Full text of this dissertation may be available via the University of Florida Libraries web site. Please check http://www.uflib.ufl.edu/etd.html)

  8. Large Footprint LiDAR Data Processing for Ground Detection and Biomass Estimation

    Science.gov (United States)

    Zhuang, Wei

    Ground detection in large footprint waveform Light Detection And Ranging (LiDAR) data is important in calculating and estimating downstream products, especially in forestry applications. For example, tree heights are calculated as the difference between the ground peak and first returned signal in a waveform. Forest attributes, such as aboveground biomass, are estimated based on the tree heights. This dissertation investigated new metrics and algorithms for estimating aboveground biomass and extracting ground peak location in large footprint waveform LiDAR data. In the first manuscript, an accurate and computationally efficient algorithm, named Filtering and Clustering Algorithm (FICA), was developed based on a set of multiscale second derivative filters for automatically detecting the ground peak in an waveform from Land, Vegetation and Ice Sensor. Compared to existing ground peak identification algorithms, FICA was tested in different land cover type plots and showed improved accuracy in ground detections of the vegetation plots and similar accuracy in developed area plots. Also, FICA adopted a peak identification strategy rather than following a curve-fitting process, and therefore, exhibited improved efficiency. In the second manuscript, an algorithm was developed specifically for shrub waveforms. The algorithm only partially fitted the shrub canopy reflection and detected the ground peak by investigating the residual signal, which was generated by deducting a Gaussian fitting function from the raw waveform. After the deduction, the overlapping ground peak was identified as the local maximum of the residual signal. In addition, an applicability model was built for determining waveforms where the proposed PCF algorithm should be applied. In the third manuscript, a new set of metrics was developed to increase accuracy in biomass estimation models. The metrics were based on the results of Gaussian decomposition. They incorporated both waveform intensity represented by the area covered by a Gaussian function and its associated heights, which was the centroid of the Gaussian function. By considering signal reflection of different vegetation layers, the developed metrics obtained better estimation accuracy in aboveground biomass when compared to existing metrics. In addition, the new developed metrics showed strong correlation with other forest structural attributes, such as mean Diameter at Breast Height (DBH) and stem density. In sum, the dissertation investigated the various techniques for large footprint waveform LiDAR processing for detecting the ground peak and estimating biomass. The novel techniques developed in this dissertation showed better performance than existing methods or metrics.

  9. Building a LiDAR point cloud simulator: Testing algorithms for high resolution topographic change

    Science.gov (United States)

    Carrea, Dario; Abellán, Antonio; Derron, Marc-Henri; Jaboyedoff, Michel

    2014-05-01

    Terrestrial laser technique (TLS) is becoming a common tool in Geosciences, with clear applications ranging from the generation of a high resolution 3D models to the monitoring of unstable slopes and the quantification of morphological changes. Nevertheless, like every measurement techniques, TLS still has some limitations that are not clearly understood and affect the accuracy of the dataset (point cloud). A challenge in LiDAR research is to understand the influence of instrumental parameters on measurement errors during LiDAR acquisition. Indeed, different critical parameters interact with the scans quality at different ranges: the existence of shadow areas, the spatial resolution (point density), and the diameter of the laser beam, the incidence angle and the single point accuracy. The objective of this study is to test the main limitations of different algorithms usually applied on point cloud data treatment, from alignment to monitoring. To this end, we built in MATLAB(c) environment a LiDAR point cloud simulator able to recreate the multiple sources of errors related to instrumental settings that we normally observe in real datasets. In a first step we characterized the error from single laser pulse by modelling the influence of range and incidence angle on single point data accuracy. In a second step, we simulated the scanning part of the system in order to analyze the shifting and angular error effects. Other parameters have been added to the point cloud simulator, such as point spacing, acquisition window, etc., in order to create point clouds of simple and/or complex geometries. We tested the influence of point density and vitiating point of view on the Iterative Closest Point (ICP) alignment and also in some deformation tracking algorithm with same point cloud geometry, in order to determine alignment and deformation detection threshold. We also generated a series of high resolution point clouds in order to model small changes on different environments (erosion, landslide monitoring, etc) and we then tested the use of filtering techniques using 3D moving windows along the space and time, which considerably reduces data scattering due to the benefits of data redundancy. In conclusion, the simulator allowed us to improve our different algorithms and to understand how instrumental error affects final results. And also, improve the methodology of scans acquisition to find the best compromise between point density, positioning and acquisition time with the best accuracy possible to characterize the topographic change.

  10. Hydrodynamic Aspects at Vitória Bay Mouth, ES

    Scientific Electronic Library Online (English)

    FLÁVIA A.A., GARONCE; VALÉRIA S., QUARESMA.

    2014-06-01

    Full Text Available SciELO Brazil | Language: English Abstract in portuguese Entender o comportamento hidrodinâmico e o transporte de MPS é de grande importância em regiões portuárias como o Porto de Vitória, localizado na Baía de Vitória, Vitória-ES, Brasil. A Baía de Vitória, é um estuário que nunca foi alvo de pesquisas sistemáticas de análise temporal com objetivo de ide [...] ntificar suas características hidrodinâmicas e de troca de MPS. Assim, esse estudo visa investigar os fluxos de sal e MPS na desembocadura do estuário da baía de Vitória, através da compreensão da variação temporal da salinidade, temperatura e correntes ao longo da coluna d'água e na seção transversal do canal. Os resultados mostraram que a desembocadura estuarina tendeu a apresentar uma estratificação parcial nos períodos de quadratura e pouca estratificação no período de sizígia. O padrão de circulação neste trecho do estuário é influenciado principalmente pela maré, com pequena influência da descarga fluvial. Em relação ao MPS, a desembocadura do estuário mostrou uma tendência de baixa concentração, com os maiores valores ocorrendo durante a estação seca. Uma forte relação momentânea foi observada entre os fluxos de MPS e sal. Apesar de todos os dados terem sido coletados na desembocadura do estuário, o sistema mostrou uma importação de sal em todos os ciclos e importação de MPS em três dos quatro ciclos de maré estudados. Assim a Baía de Vitória não está exportando MPS para a plataforma adjacente. Abstract in english Understading the hydrodynamic behavior and suspended particulated matter (SPM) transport are of great importance in port regions such as Vitória Harbor, which is located at Vitória Bay, Vitória – ES, Brazil. Vitória Bay is an estuary that has not been systematically assessed through a temporal analy [...] sis in order to identify its hydrodynamics characteristics and SPM exchange. This study aims to investigate salt and suspended particulate matter flux at the estuarine mouth of Vitória Bay by understanding the temporal variation of salinity, temperature and tidal currents within the water column and at the channel crosssection. Results showed that the estuarine mouth tended to present partial stratification periods during neap tides and little stratification in spring tides. The circulation pattern was mainly influenced by the tide, with little influence from river discharge. With regard to the SPM, the mouth of the estuary tended to show low concentrations, with the highest values occurring during the dry season. A close relationship between momentary discharge, SPM and salt fluxes was observed. Despite all the data was collected at the mouth of the estuary, the system showed an importation trend of salt in all cycles and SPM importation for three of the four studied tidal cycles. Thus, Vitoria Bay is not exporting SPM to the adjacent inner shelf.

  11. Belleza, sí, pero ¿qué es eso?

    Scientific Electronic Library Online (English)

    Jorge Ariel, Madrazo.

    Full Text Available El concepto de belleza es relativo al imaginario colectivo y los dictados culturales de las diversas épocas, si bien admite casi tantas miradas como individuos. Un contrapeso a tal relativismo: aun hoy suele hablarse de la supuesta "belleza eterna" del arte griego. En épocas de cambio y al amparo de [...] rupturas estéticas-filosóficas, artistas y pensadores se han rebelado contra los modelos canónicos. Así, la revolución romántica proclamó que lo bello no sólo podría no depender de la equidad y armonía pregonadas desde Aristóteles, sino que consistiría en la total subversión de dicha armonía. En lo que va del placer al goce lacaniano, irrumpe la belleza de lo feo, o de su representación. La revolución copernicana y el yo escindido de Freud trastornaron las ideas de eje único y de verdad. ¿El arte ya no existe? Las visiones estéticas enfrentadas dan paso a emergentes capaces de cuestionar los dogmas pre-establecidos Abstract in english The concept of beauty is related to the collective imaginary and the cultural dictates of diverse eras, as well as admitting almost as many visions as individuals. A counterweight to such relativism: even today we often hear of the supposed "eternal beauty" of Greek art. In periods of change and und [...] er the shelter of aesthetic-philosophical ruptures, artists and thinkers have rebelled against those canonical models. The romantic revolution proclaimed that the beautiful could not only not depend on the equality and harmony proffered since Aristotle, but that it would consist of the total subversion of that harmony. In respect to the pleasure of Lacanian joy, it is the beauty of ugliness that emerges, or its representation. The Copernican Revolution and Freud’s divided ego upset the ideas of one axis and of truth. Does art no longer exist? The confrontation of aesthetic visions gives way to emergent ones that are capable of questioning pre-established dogmas

  12. GIS-Based Roughness Derivation for Flood Simulations: A Comparison of Orthophotos, LiDAR and Crowdsourced Geodata

    Directory of Open Access Journals (Sweden)

    Helen Dorn

    2014-02-01

    Full Text Available Natural disasters like floods are a worldwide phenomenon and a serious threat to mankind. Flood simulations are applications of disaster control, which are used for the development of appropriate flood protection. Adequate simulations require not only the geometry but also the roughness of the Earth’s surface, as well as the roughness of the objects hereon. Usually, the floodplain roughness is based on land use/land cover maps derived from orthophotos. This study analyses the applicability of roughness map derivation approaches for flood simulations based on different datasets: orthophotos, LiDAR data, official land use data, OpenStreetMap data and CORINE Land Cover data. Object-based image analysis is applied to orthophotos and LiDAR raster data in order to generate land cover maps, which enable a roughness parameterization. The vertical vegetation structure within the LiDAR point cloud is used to derive an additional floodplain roughness map. Further roughness maps are derived from official land use data, OpenStreetMap and CORINE Land Cover datasets. Six different flood simulations are applied based on one elevation data but with the different roughness maps. The results of the hydrodynamic–numerical models include information on flow velocity and water depth from which the additional attribute flood intensity is calculated of. The results based on roughness maps derived from LiDAR data and OpenStreetMap data are comparable, whereas the results of the other datasets differ significantly.

  13. DEM Development from Ground-Based LiDAR Data: A Method to Remove Non-Surface Objects

    Directory of Open Access Journals (Sweden)

    Maneesh Sharma

    2010-11-01

    Full Text Available Topography and land cover characteristics can have significant effects on infiltration, runoff, and erosion processes on watersheds. The ability to model the timing and routing of surface water and erosion is affected by the resolution of the digital elevation model (DEM. High resolution ground-based Light Detecting and Ranging (LiDAR technology can be used to collect detailed topographic and land cover characteristic data. In this study, a method was developed to remove vegetation from ground-based LiDAR data to create high resolution DEMs. Research was conducted on intensively studied rainfall–runoff plots on the USDA-ARS Walnut Gulch Experimental Watershed in Southeast Arizona. LiDAR data were used to generate 1 cm resolution digital surface models (DSM for 5 plots. DSMs created directly from LiDAR data contain non-surface objects such as vegetation cover. A vegetation removal method was developed which used a slope threshold and a focal mean filter method to remove vegetation and create bare earth DEMs. The method was validated on a synthetic plot, where rocks and vegetation were added incrementally. Results of the validation showed a vertical error of ±7.5 mm in the final DEM.

  14. Fine-spatial scale predictions of understory species using climate- and LiDAR-derived terrain and canopy metrics

    Science.gov (United States)

    Nijland, Wiebe; Nielsen, Scott E.; Coops, Nicholas C.; Wulder, Michael A.; Stenhouse, Gordon B.

    2014-01-01

    Food and habitat resources are critical components of wildlife management and conservation efforts. The grizzly bear (Ursus arctos) has diverse diets and habitat requirements particularly for understory plant species, which are impacted by human developments and forest management activities. We use light detection and ranging (LiDAR) data to predict the occurrence of 14 understory plant species relevant to bear forage and compare our predictions with more conventional climate- and land cover-based models. We use boosted regression trees to model each of the 14 understory species across 4435 km2 using occurrence (presence-absence) data from 1941 field plots. Three sets of models were fitted: climate only, climate and basic land and forest covers from Landsat 30-m imagery, and a climate- and LiDAR-derived model describing both the terrain and forest canopy. Resulting model accuracies varied widely among species. Overall, 8 of 14 species models were improved by including the LiDAR-derived variables. For climate-only models, mean annual precipitation and frost-free periods were the most important variables. With inclusion of LiDAR-derived attributes, depth-to-water table, terrain-intercepted annual radiation, and elevation were most often selected. This suggests that fine-scale terrain conditions affect the distribution of the studied species more than canopy conditions.

  15. Exposure Histories of Shergottites Dar Al Gani 476/489/670/735 and Sayh Al Uhaymir 005

    Science.gov (United States)

    Nishiizumi, K.; Caffee, M. W.; Jull, A. J. T.; Klandrud, S. E.

    2001-03-01

    We measured cosmogenic nuclides, ^14C, ^36Cl, ^26Al, and ^10Be in Dar al Gani 476, 489, 670, and 735 and Sayh al Uhaymir 005 basaltic shergottites. The exposure ages and terrestrial ages of these Martian meteorites were investigated.

  16. Exposure History of Shergottites Dar Al Gani 476/489/670/735 and Sayh Al Uhaymir 005

    Science.gov (United States)

    Nishiizumi, K.; Caffee, M. W.; Jull, A. J. T.; Klandrud, S. E.

    2001-01-01

    We measured cosmogenic nuclides, C-14, Cl-36, Al-26, and Be-10 in Dar al Gani 476, 489, 670, and 735 and Sayh al Uhaymir 005 basaltic shergottites. The exposure ages and terrestrial ages of these martian meteorites were investigated. Additional information is contained in the original extended abstract.

  17. Ancient Maya Regional Settlement and Inter-Site Analysis: The 2013 West-Central Belize LiDAR Survey

    Directory of Open Access Journals (Sweden)

    Arlen F. Chase

    2014-09-01

    Full Text Available During April and May 2013, a total of 1057 km2 of LiDAR was flown by NCALM for a consortium of archaeologists working in West-central Belize, making this the largest surveyed area within the Mayan lowlands. Encompassing the Belize Valley and the Vaca Plateau, West-central Belize is one of the most actively researched parts of the Maya lowlands; however, until this effort, no comprehensive survey connecting all settlement had been conducted. Archaeological projects have investigated at least 18 different sites within this region. Thus, a large body of archaeological research provides both the temporal and spatial parameters for the varied ancient Maya centers that once occupied this area; importantly, these data can be used to help interpret the collected LiDAR data. The goal of the 2013 LiDAR campaign was to gain information on the distribution of ancient Maya settlement and sites on the landscape and, particularly, to determine how the landscape was used between known centers. The data that were acquired through the 2013 LiDAR campaign have significance for interpreting both the composition and limits of ancient Maya political units. This paper presents the initial results of these new data and suggests a developmental model for ancient Maya polities.

  18. Fusion of terrestrial LiDAR and tomographic mapping data for 3D karst landform investigation

    Science.gov (United States)

    Höfle, B.; Forbriger, M.; Siart, C.; Nowaczinski, E.

    2012-04-01

    Highly detailed topographic information has gained in importance for studying Earth surface landforms and processes. LiDAR has evolved into the state-of-the-art technology for 3D data acquisition on various scales. This multi-sensor system can be operated on several platforms such as airborne LS (ALS), mobile LS (MLS) from moving vehicles or stationary on ground (terrestrial LS, TLS). In karst research the integral investigation of surface and subsurface components of solution depressions (e.g. sediment-filled dolines) is required to gather and quantify the linked geomorphic processes such as sediment flux and limestone dissolution. To acquire the depth of the different subsurface layers, a combination of seismic refraction tomography (SRT) and electrical resistivity tomography (ERT) is increasingly applied. This multi-method approach allows modeling the extension of different subsurface media (i.e. colluvial fill, epikarst zone and underlying basal bedrock). Subsequent fusion of the complementary techniques - LiDAR surface and tomographic subsurface data - first-time enables 3D prospection and visualization as well as quantification of geomorphometric parameters (e.g. depth, volume, slope and aspect). This study introduces a novel GIS-based method for semi-automated fusion of TLS and geophysical data. The study area is located in the Dikti Mountains of East Crete and covers two adjacent dolines. The TLS data was acquired with a Riegl VZ-400 scanner from 12 scan positions located mainly at the doline divide. The scan positions were co-registered using the iterative closest point (ICP) algorithm of RiSCAN PRO. For the digital elevation rasters a resolution of 0.5 m was defined. The digital surface model (DSM) of the study was derived by moving plane interpolation of all laser points (including objects) using the OPALS software. The digital terrain model (DTM) was generated by iteratively "eroding" objects in the DSM by minimum filter, which additionally accounts for thresholds on slope and object size in order to avoid erosion of the doline slopes. Three SRT cross-sections (Geometrics, 48 channels) and three ERT profiles (Geotom, 100 electrodes) were measured. After post processing with RAYFRACT and RES2DINV software packages, subsurface media were identified taking advantage of different sensitivities of each geophysical technique by cross-checking and matching all outcomes. To join the LiDAR DTM and the subsurface profiles, symmetry of the subsurface bedrock zone is assumed. This allows extrapolation from seismic and resistivity data to the entire doline bottom. The extrapolated point cloud data is then joined with the surface LiDAR data by spline interpolation of the transition zone between surface and subsurface bedrock. The entire fusion procedure of the DTM and the tomographic cross-sections is implemented in the GRASS GIS environment. Finally, the derived digital terrain and subsurface model (DTSM) is used to extract the geomorphological parameters of the landforms (e.g. total volume, sediment volume). Tests using different input datasets (e.g. DSM, DTM, DTSM) for parameter derivation at varying cell resolutions clearly indicate the need for high-resolution terrain and subsurface data for obtaining the geometry and function of karst landforms.

  19. Analysis of airborne LiDAR as a basis for digital soil mapping in Alpine areas

    Science.gov (United States)

    Kringer, K.; Tusch, M.; Geitner, C.; Meißl, G.; Rutzinger, M.

    2009-04-01

    Especially in mountainous regions like the Alps the formation of soil is highly influenced by relief characteristics. Among all factors included in Jenny's (1941) model for soil development, relief is the one most commonly used in approaches to create digital soil maps and to derive soil properties from secondary data sources (McBratney et al. 2003). Elevation data, first order (slope, aspect) and second order derivates (plan, profile and cross-sectional curvature) as well as complex morphometric parameters (various landform classifications, e.g., Wood 1996) and compound indices (e.g., topographic wetness indices, vertical distance to drainage network, insolation) can be calculated from digital elevation models (DEM). However, while being an important source of information for digital soil mapping on small map scales, "conventional" DEMs are of limited use for the design of large scale conceptual soil maps for small areas due to rather coarse raster resolutions with cell sizes ranging from 20 to 100 meters. Slight variations in elevation and small landform features might not be discernible even though they might have a significant effect to soil formation, e.g., regarding the influence of groundwater in alluvial soils or the extent of alluvial fans. Nowadays, Airborne LiDAR (Light Detection And Ranging) provides highly accurate data for the elaboration of high-resolution digital terrain models (DTM) even in forested areas. In the project LASBO (Laserscanning in der Bodenkartierung) the applicability of digital terrain models derived from LiDAR for the identification of soil-relevant geomorphometric parameter is investigated. Various algorithms which were initially designed for coarser raster data are applied on high-resolution DTMs. Test areas for LASBO are located in the region of Bruneck (Italy) and near the municipality of Kramsach in the Inn Valley (Austria). The freely available DTM for Bruneck has a raster resolution of 2.5 meters while in Kramsach a DTM with a cell size of 1 meter is used. Firstly, morphometric analyses are carried out using the open-source GIS-software packages SAGA (System for Automated Geoscientific Analyses) and GRASS (Geographic Resources Analysis Support System). In a next step, an object-based image analysis with the commercial software Definiens Professional is used to classify the different terrain parameters based on fuzzy membership functions. Further information on geology and land use are also integrated to optimize the results of the classification. Besides the distribution of soil units, basic soil parameters like horizon or solum depth and groundwater influence ("gleysation") will be modelled to reassess the full potential of DTMs derived from LiDAR for digital soil mapping of mountainous regions. First attempts show that a very high raster resolution makes it difficult to differentiate between actual changes of elevation and minor differences between raster cells which mainly remained after DTM filtering, or are caused by the interpolation of point data. Eliminating errors in the DTM is difficult and needs manual interaction to avoid a general loss of significant information. Various concepts are combined to achieve an optimised balance between the highest possible accuracy and a minimal loss of information. Different resampling methods and filter techniques are used to modify the original data in order to capture relief features and soil properties at different scales. The results finally are verified using aerial photographs, existing soil maps and field mapping of soil and geomorphologic features. DTMs with a coarser resolution of 10 meters (Kramsach) and 20 meters (Bruneck) respectively generated with photogrammetric methods are also used to compare the results and estimate the chances and limitations of DTMs derived from LiDAR for digital soil mapping.

  20. A LiDAR method of canopy structure retrieval for wind modeling of heterogeneous forests

    DEFF Research Database (Denmark)

    Boudreault, Louis-Etienne; Bechmann, Andreas

    2015-01-01

    The difficulty of obtaining accurate information about the canopy structure is a current limitation towards higher accuracy in numerical predictions of the wind field in forested terrain. The canopy structure in computational fluid dynamics is specified through the frontal area density and this information is required for each grid point in the three-dimensional computational domain. By using raw data from aerial LiDAR scans together with the Beer-Lambert law, we propose and test a method to calculate and grid highly variable and realistic frontal area density input. An extensive comparison with ground-based measurements of the vertically summed frontal area density (or plant area index) and tree height was used to optimize the method, both in terms of plant area index magnitude and spatial variability. The resolution of the scans was in general low (

  1. G-LiHT: Goddard's LiDAR, Hyperspectral and Thermal Airborne Imager

    Science.gov (United States)

    Cook, Bruce; Corp, Lawrence; Nelson, Ross; Morton, Douglas; Ranson, Kenneth J.; Masek, Jeffrey; Middleton, Elizabeth

    2012-01-01

    Scientists at NASA's Goddard Space Flight Center have developed an ultra-portable, low-cost, multi-sensor remote sensing system for studying the form and function of terrestrial ecosystems. G-LiHT integrates two LIDARs, a 905 nanometer single beam profiler and 1550 nm scanner, with a narrowband (1.5 nanometers) VNIR imaging spectrometer and a broadband (8-14 micrometers) thermal imager. The small footprint (approximately 12 centimeters) LIDAR data and approximately 1 meter ground resolution imagery are advantageous for high resolution applications such as the delineation of canopy crowns, characterization of canopy gaps, and the identification of sparse, low-stature vegetation, which is difficult to detect from space-based instruments and large-footprint LiDAR. The hyperspectral and thermal imagery can be used to characterize species composition, variations in biophysical variables (e.g., photosynthetic pigments), surface temperature, and responses to environmental stressors (e.g., heat, moisture loss). Additionally, the combination of LIDAR optical, and thermal data from G-LiHT is being used to assess forest health by sensing differences in foliage density, photosynthetic pigments, and transpiration. Low operating costs (approximately $1 ha) have allowed us to evaluate seasonal differences in LiDAR, passive optical and thermal data, which provides insight into year-round observations from space. Canopy characteristics and tree allometry (e.g., crown height:width, canopy:ground reflectance) derived from G-LiHT data are being used to generate realistic scenes for radiative transfer models, which in turn are being used to improve instrument design and ensure continuity between LiDAR instruments. G-LiHT has been installed and tested in aircraft with fuselage viewports and in a custom wing-mounted pod that allows G-LiHT to be flown on any Cessna 206, a common aircraft in use throughout the world. G-LiHT is currently being used for forest biomass and growth estimation in the CONUS and Mexico in support of NASA's Carbon Monitoring System (CMS) and AMIGA-Carb (AMerican Icesat Glas Assessment of Carbon). For NASA's CMS, wall-to-wall G-LiHT data have been acquired over intensive study sites with historic LiDAR datasets, dense inventory data, stem maps and flux tower observations. For AMIGA-Carb, G-LiHT transects have been acquired over ICESat tracks and USDA-FS inventory plots throughout the CONUS, and similar data will be acquired in Mexico during 2013. This talk will highlight recent science results from continental-scale transects landscape-scale deployments of G-LiHT, as well as seasonal forest dynamics from repeat pass G-LiHT acquisitions.

  2. Estimation of aquifer transmissivity from Dar-Zarrouk parameters in porous media

    Science.gov (United States)

    Niwas, Sri; Singhal, D. C.

    The aim of this paper is to establish an analytical relationship between the aquifer parameters for porous media and the so-called Dar-Zarrouk parameters so that the former can best be estimated from the surface resistivity measurements. Taking the two fundamental laws, viz. Darcy's law of fluid flow and Ohm's law of current flow, analytical relationships between transmissivity and transverse resistance, as well as transmissivity and longitudinal conductance have been established. It was found that the relationship between transverse resistance and transmissivity is more meaningful, as the product of hydraulic conductivity and electrical conductivity of an aquifer may be assumed to be constant for an area with a particular geological setting and range of water quality. This is verified by analysing the data given by Kelly.

  3. Fine-scale ignimbrite morphology revealed in LiDAR at Crater Lake, OR

    Science.gov (United States)

    Robinson, J. E.; Bacon, C. R.; Wright, H. M.

    2011-12-01

    Mount Mazama erupted ~7,700 years ago resulting in the collapse of Crater Lake caldera, ash fall across the Pacific Northwest, and emplacement of compositionally zoned ignimbrite. Early climactic ignimbrite contains uniform rhyodacitic pumice and traveled far from the vent, whereas late, less mobile ignimbrite is dominated by crystal-rich andesitic scoria and mafic crystal mush. Funded by the USGS, NPS, and FHWA, the DOGAMI-led Oregon LiDAR Consortium contracted with Watershed Services to collect ~800 km2 of LiDAR over Crater Lake National Park from Aug 2010 to Sept 2010. Ground laser returns have an average density of 1.63 returns/m2 over the heavily forested area of interest. The data have a lateral RMSE and vertical accuracy of 0.05 m. A bare earth terrain model allows a virtual removal of the forest, revealing fine-scale surface morphology, notably in the climactic ignimbrite. Secondary pyroclastic flows, explosion craters, erosion by water, and compaction-related deformation modified the originally smooth ignimbrite surface. Distinct pyroclastic flow fronts are evident in the LiDAR in Annie Creek valley. Leveed flows stand approximately 5 m above the lower ignimbrite surface, and individual toes are about 1-2 m high. Preliminary field checking indicates that rhyodacitic pumice dominates the lower ignimbrite surface, but the leveed flows are a subequal mix of locally oxidized rhyodacitic pumice and andesitic scoria. We hypothesize that these deposits were secondary pyroclastic flows formed by gravitational failure of late ignimbrite. In the Castle Creek valley, is a 2-meter collapse scarp that may have spawned a small secondary pyroclastic flow; several such headwall scarps are present in Sand Creek valley. Differential compaction features are common in many thick ignimbrites. We suggest this caused the deformation of the ignimbrite apparent in the LiDAR. In Annie Creek valley are a series of flow parallel asymmetric ridges, with shallower slopes toward the valley center, in the surface of the rhyodacitic ignimbrite. The ridges are 1-2 m high, and have a variable wavelength averaging 60 m. We hypothesize that this terrain is a series of antithetic faults due to downbending towards the thickest part of the ignimbrite. The ignimbrite near the Pumice Desert is likely over 100 m thick. Here, cracks positioned on topographic highs or at breaks in slope are 50 m to 800 m long and up to 30 m wide. The cracks open towards the thickest part of the ignimbrite in the downslope direction. They appear to be tension fractures that opened because of differential compaction of the ignimbrite. Breakaway fractures mark where ignimbrite thickness abruptly decreases laterally, such as north-northeast of the caldera and at valley margins. Some fractures show evidence of water erosion during formation of fractures. On the lee side of Timber Crater, north of Crater Lake, is a series of N-S trending ribs composed of pumice fall from the climactic eruption deposited on glaciated andesite lava. Timber Crater lies on the main dispersal axis of the pumice fall. We suggest that high-energy pyroclastic flows encountered topographic bumps on the flanks of Timber Crater. This affected flow turbulence causing linear troughs to erode into the fall deposit and leaving pumice-fall ribs.

  4. Byssinosis and other respiratory disorders among textile mill workers in Bahr Dar northwest Ethiopia.

    Science.gov (United States)

    Abebe, Y; Seboxa, T

    1995-01-01

    The prevalence of byssinosis and other respiratory symptoms were studied among 433 workers who were occupationally exposed to cotton dust in Bahr Dar Textile Mill. One-hundred-one nonexposed workers living in the same geographical area were included as controls. All of the subjects completed the British Medical Research Council Questionnaire. Pulmonary function tests were administered on a vitalograph spirometer before starting the shift for all subjects, and after at least four hours of exposure for exposed subjects. Among the cotton dust exposed workers, byssinotics behaved distinctly and showed the maximum acute and chronic changes in pulmonary functions. The overall prevalence of byssinosis was 45.5%. The highest prevalence was found in carding (57.9%) and in ring frame (57.1%) operatives and the lowest in weaving preparatory section (32.1%). Unlike bronchial asthma, chronic cough and chronic bronchitis were significantly higher (p importance in minimizing the prevalence of byssinosis and other respiratory disorders. PMID:7895745

  5. How integrating 3D LiDAR data in the dike surveillance protocol: The French case

    Science.gov (United States)

    Bretar, F.; Mériaux, P.; Fauchard, C.

    2012-04-01

    The recent and dramatic floods of the last years in Europe (e.g. Rhône river major flood, December 2003, Windstorm Xynthia, February 2010, in France) and in the United-States (Hurricane Katrina, August 2005) showed the vulnerability of flood or coastal defence systems. The first key point for avoiding these dramatic damages and the high cost of a failure and its consequences lies in the appropriate conception and construction of the dikes, but above all in the relevance of the surveillance protocol. Many factors introduce weaknesses in the fluvial or maritime dikes. Most of them are old embankment structures. For instance, some of the French Loire River dikes were built several centuries ago. They may have been rebuilt, modified, heightened several times, with some materials that do not necessarily match the original conception of the structure. In other respects, tree roots or animal burrows could modify the structure of the dike and reduce the watertightness or mechanical properties. The French government has built a national database, "BarDigues", since 1999 to inventory and characterize dikes. Today, there are approx. 9000 km of dikes protecting 1.5 to 2 millions of people. In the meantime, a GIS application, called « Dike SIRS » [Maurel P., 2004] , provides an operational and accurate tool to several great stakeholders in charge of managing more than 100 km of dikes. Today, the dike surveillance and diagnosis protocol consists in identifying the weaknesses of the structure and providing the degree of safety by making a preliminary study (historical research, geological and morphodynamic study, topography), geophysical study (e.g. electromagnetic methods and electrical resistivity tomography) and at last geotechnical study (e.g. drillings and stability modelling) at the very local scale when necessary [Mériaux P. & Royet P, 2007] . Considering the stretch of hundreds of kilometres, rapid, cost-effective and reliable techniques for surveying the dike must be carried out. A LiDAR system is able to acquire data on a dike structure of up to 80 km per day, which makes the use of this technique also valuable in case of emergency situations. It provides additional valuable products like precious information on dike slopes and crest or their near environment (river banks, etc.). Moreover, in case of vegetation, LiDAR data makes possible to study hidden structures or defaults from images like the erosion of riverbanks under forestry vegetation. The possibility of studying the vegetation is also of high importance: the development of woody vegetation near or onto the dike is a major risk factor. Surface singularities are often signs of disorder or suspected disorder in the dike itself: for example a subsidence or a sinkhole on a ridge may result from internal erosion collapse. Finally, high resolution topographic data contribute to build specific geomechanical model of the dike that, after incorporating data provided by geophysical and geotechnical surveys, are integrated in the calculations of the structure stability. Integrating the regular use of LiDAR data in the dike surveillance protocol is not yet operational in France. However, the high number of French stakeholders at the national level (on average, there is one stakeholder for only 8-9km of dike !) and the real added value of LiDAR data makes a spatial data infrastructure valuable (webservices for processing the data, consulting and filling the database on the field when performing the local diagnosis)

  6. Guild-specific responses of avian species richness to LiDAR-derived habitat heterogeneity

    Science.gov (United States)

    Weisberg, Peter J.; Dilts, Thomas E.; Becker, Miles E.; Young, Jock S.; Wong-Kone, Diane C.; Newton, Wesley E.; Ammon, Elisabeth M.

    2014-08-01

    Ecological niche theory implies that more heterogeneous habitats have the potential to support greater biodiversity. Positive heterogeneity-diversity relationships have been found for most studies investigating animal taxa, although negative relationships also occur and the scale dependence of heterogeneity-diversity relationships is little known. We investigated multi-scale, heterogeneity-diversity relationships for bird communities in a semi-arid riparian landscape, using airborne LiDAR data to derive key measures of structural habitat complexity. Habitat heterogeneity-diversity relationships were generally positive, although the overall strength of relationships varied across avian life history guilds (R2 range: 0.03-0.41). Best predicted were the species richness indices of cavity nesters, habitat generalists, woodland specialists, and foliage foragers. Heterogeneity-diversity relationships were also strongly scale-dependent, with strongest associations at the 200-m scale (4 ha) and weakest associations at the 50-m scale (0.25 ha). Our results underscore the value of LiDAR data for fine-grained quantification of habitat structure, as well as the need for biodiversity studies to incorporate variation among life-history guilds and to simultaneously consider multiple guild functional types (e.g. nesting, foraging, habitat). Results suggest that certain life-history guilds (foliage foragers, cavity nesters, woodland specialists) are more susceptible than others (ground foragers, ground nesters, low nesters) to experiencing declines in local species richness if functional elements of habitat heterogeneity are lost. Positive heterogeneity-diversity relationships imply that riparian conservation efforts need to not only provide high-quality riparian habitat locally, but also to provide habitat heterogeneity across multiple scales.

  7. A saturated SSR/DArT linkage map of Musa acuminata addressing genome rearrangements among bananas

    Directory of Open Access Journals (Sweden)

    Matsumoto Takashi

    2010-04-01

    Full Text Available Abstract Background The genus Musa is a large species complex which includes cultivars at diploid and triploid levels. These sterile and vegetatively propagated cultivars are based on the A genome from Musa acuminata, exclusively for sweet bananas such as Cavendish, or associated with the B genome (Musa balbisiana in cooking bananas such as Plantain varieties. In M. acuminata cultivars, structural heterozygosity is thought to be one of the main causes of sterility, which is essential for obtaining seedless fruits but hampers breeding. Only partial genetic maps are presently available due to chromosomal rearrangements within the parents of the mapping populations. This causes large segregation distortions inducing pseudo-linkages and difficulties in ordering markers in the linkage groups. The present study aims at producing a saturated linkage map of M. acuminata, taking into account hypotheses on the structural heterozygosity of the parents. Results An F1 progeny of 180 individuals was obtained from a cross between two genetically distant accessions of M. acuminata, 'Borneo' and 'Pisang Lilin' (P. Lilin. Based on the gametic recombination of each parent, two parental maps composed of SSR and DArT markers were established. A significant proportion of the markers (21.7% deviated (p Conclusions We propose a synthetic map with 11 linkage groups containing 489 markers (167 SSRs and 322 DArTs covering 1197 cM. This first saturated map is proposed as a "reference Musa map" for further analyses. We also propose two complete parental maps with interpretations of structural rearrangements localized on the linkage groups. The structural heterozygosity in P. Lilin is hypothesized to result from a duplication likely accompanied by an inversion on another chromosome. This paper also illustrates a methodological approach, transferable to other species, to investigate the mapping of structural rearrangements and determine their consequences on marker segregation.

  8. Coastal change analysis of Lovells Island using high resolution ground based LiDAR imagery

    Science.gov (United States)

    Ly, Jennifer K.

    Many methods have been employed to study coastline change. These methods range from historical map analysis to GPS surveys to modern airborne LiDAR and satellite imagery. These previously used methods can be time consuming, labor intensive, and expensive and have varying degrees of accuracy and temporal coverage. Additionally, it is often difficult to apply such techniques in direct response to an isolated event within an appropriate temporal framework. Here we utilize a new ground based Canopy Biomass LiDAR (CBL) system built at The University of Massachusetts Boston (in collaboration with the Rochester Institute of Technology) in order to identify and analyze coastal change on Lovells Island, Boston Harbor. Surveys of a bluff developing in an eroding drumlin and beach cusps on a high-energy cobble beach on Lovells Island were conducted in June, September and December of 2013. At each site for each survey, the CBL was set up and multiple scans of each feature were taken on a predetermined transect that was established parallel to the high-water mark at distances relative to the scale of the bluff and cusps. The scans from each feature were compiled, integrated and visualized using Meshlab. Results from our surveys indicate that the highly portable and easy to deploy CBL system produces images of exceptional clarity, with the capacity to resolve small-scale changes to coastal features and systems. The CBL, while still under development (and coastal surveying protocols with it are just being established), appears to be an ideal tool for analyzing coastal geological features and is anticipated to prove to be a useful tool for the observation and analysis of coastal change. Furthermore, there is significant potential for utilizing the low cost ultra-portable CBL in frequent deployments to develop small-scale erosion rate and sediment budget analyses.

  9. Underwater monitoring experiment using hyperspectral sensor, LiDAR and high resolution satellite imagery

    Science.gov (United States)

    Yang, Chan-Su; Kim, Sun-Hwa

    2014-10-01

    In general, hyper-spectral sensor, LiDAR and high spatial resolution satellite imagery for underwater monitoring are dependent on water clarity or water transparency that can be measured using a Secchi disk or satellite ocean color data. Optical properties in the sea waters of South Korea are influenced mainly by a strong tide and oceanic currents, diurnal, daily and seasonal variations of water transparency. The satellite-based Secchi depth (ZSD) analysis showed the applicability of hyper-spectral sensor, LiDAR and optical satellite, determined by the location connected with the local distribution of Case 1 and 2 waters. The southeast coastal areas of Jeju Island are selected as test sites for a combined underwater experiment, because those areas represent Case 1 water. Study area is a small port (Airborne Hyperspectral VNIR Imager (0.38-1.05 microns), the Coastal Zone Mapping and Imaging Lidar (CZMIL) and Korean Multi-purpose Satellite-3 (KOMPSAT-3) with 2.8 meter multi-spectral resolution. The experimental results were affected by water clarity and surface condition, and the bathymetric results of three sensors show some differences caused by sensor-itself, bathymetric algorithm and tide level. It is shown that CASI-1500 was applicable for bathymetry and underwater target detection in this area, but KOMPSAT-3 should be improved for Case 1 water. Although this experiment was designed to compare underwater monitoring ability of LIDAR, CASI-1500, KOMPSAT-3 data, this paper was based on initial results and suggested only results about the bathymetry and underwater target detection.

  10. Comparison of Morphometry of Active Landslides in Differing Geological Settings Using LiDAR-derived DEMs

    Science.gov (United States)

    Kasai, M.; Kuda, T.; Okuda, S.; Fujisawa, K.; Asahina, T.; Matsuda, M.

    2008-12-01

    Deep seated landslides develop fine-scale geomorphic forms such as cracks and internal scars, forming rough surfaces as they move. Because the data density of LiDAR measurement is of sufficient detail to extract these forms, DEM-derived surface fabric filters can be used to estimate their recent activity. To utilize LiDAR data for this purpose, it is first necessary to establish the relationships that exist between filter values and actual surface features, and slide activities. These relationships are expected to differ between sites, reflecting the local geological and topographic characteristics, and the resolution and grid size of DEMs. In this presentation, these relationships are investigated at three study sites in Japan. The major geologies were Tertiary Tuff at two sites and sheared Mesozoic sedimentary rocks at the other. DEM cell sizes ranged from 1 to 5 m. The eigenvalue ratio, which represents the 3-dimensional surface roughness, was calculated from the DEMs. The spatial pattern of cell values within landslide blocks was compared with local surface features and slide conditions observed in the field. Results suggest that similar surface features were likely to be expressed in a higher and wider range of eigenvalue ratios as DEM grid size increased. Change in grid size, however, did not greatly alter their spatial distribution patterns. Consequently, the different major hillslope processes could be highlighted by comparing the patterns of recently active blocks from each site. In the Mesozoic sedimentary rock site, active slides contained steep slope parts which were characterized by a higher proportion of cells with an eigenvalue ratio < 2.5, when compared with surrounding areas. These low values mostly represent cracks in bedrock outcrops and scars. In contrast, the softer underlying rocks at the Tuff sites, has allowed landslides to evolve with gentle slopes, while maintaining a slow but consistent downslope motion. Here, there were a high proportion of eigenvalue ratios from 4 to 5, representing the undulating surface form.

  11. Multispectral, hyperspectral, and LiDAR remote sensing and geographic information fusion for improved earthquake response

    Science.gov (United States)

    Kruse, F. A.; Kim, A. M.; Runyon, S. C.; Carlisle, Sarah C.; Clasen, C. C.; Esterline, C. H.; Jalobeanu, A.; Metcalf, J. P.; Basgall, P. L.; Trask, D. M.; Olsen, R. C.

    2014-06-01

    The Naval Postgraduate School (NPS) Remote Sensing Center (RSC) and research partners have completed a remote sensing pilot project in support of California post-earthquake-event emergency response. The project goals were to dovetail emergency management requirements with remote sensing capabilities to develop prototype map products for improved earthquake response. NPS coordinated with emergency management services and first responders to compile information about essential elements of information (EEI) requirements. A wide variety of remote sensing datasets including multispectral imagery (MSI), hyperspectral imagery (HSI), and LiDAR were assembled by NPS for the purpose of building imagery baseline data; and to demonstrate the use of remote sensing to derive ground surface information for use in planning, conducting, and monitoring post-earthquake emergency response. Worldview-2 data were converted to reflectance, orthorectified, and mosaicked for most of Monterey County; CA. Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data acquired at two spatial resolutions were atmospherically corrected and analyzed in conjunction with the MSI data. LiDAR data at point densities from 1.4 pts/m2 to over 40 points/ m2 were analyzed to determine digital surface models. The multimodal data were then used to develop change detection approaches and products and other supporting information. Analysis results from these data along with other geographic information were used to identify and generate multi-tiered products tied to the level of post-event communications infrastructure (internet access + cell, cell only, no internet/cell). Technology transfer of these capabilities to local and state emergency response organizations gives emergency responders new tools in support of post-disaster operational scenarios.

  12. Tracking geomorphic signatures of watershed suburbanization with multitemporal LiDAR

    Science.gov (United States)

    Jones, Daniel K.; Baker, Matthew E.; Miller, Andrew J.; Jarnagin, S. Taylor; Hogan, Dianna M.

    2014-08-01

    Urban development practices redistribute surface materials through filling, grading, and terracing, causing drastic changes to the geomorphic organization of the landscape. Many studies document the hydrologic, biologic, or geomorphic consequences of urbanization using space-for-time comparisons of disparate urban and rural landscapes. However, no previous studies have documented geomorphic changes from development using multiple dates of high-resolution topographic data at the watershed scale. This study utilized a time series of five sequential light detection and ranging (LiDAR) derived digital elevation models (DEMs) to track watershed geomorphic changes within two watersheds throughout development (2002-2008) and across multiple spatial scales (0.01-1 km2). Development-induced changes were compared against an undeveloped forested watershed during the same time period. Changes in elevations, slopes, hypsometry, and surface flow pathways were tracked throughout the development process to assess watershed geomorphic alterations. Results suggest that development produced an increase in sharp topographic breaks between relatively flat surfaces and steep slopes, replacing smoothly varying hillslopes and leading to greater variation in slopes. Examinations of flowpath distributions highlight systematic modifications that favor rapid convergence in unchanneled upland areas. Evidence of channel additions in the form of engineered surface conduits is apparent in comparisons of pre- and post-development stream maps. These results suggest that topographic modification, in addition to impervious surfaces, contributes to altered hydrologic dynamics observed in urban systems. This work highlights important considerations for the use of repeat LiDAR flights in analyzing watershed change through time. Novel methods introduced here may allow improved understanding and targeted mitigation of the processes driving geomorphic changes during development and help guide future research directions for development-based watershed studies.

  13. Urban flood modelling combining top-view LiDAR data with ground-view SfM observations

    Science.gov (United States)

    Meesuk, Vorawit; Vojinovic, Zoran; Mynett, Arthur E.; Abdullah, Ahmad F.

    2015-01-01

    Remote Sensing technologies are capable of providing high-resolution spatial data needed to set up advanced flood simulation models. Amongst them, aerial Light Detection and Ranging (LiDAR) surveys or Airborne Laser Scanner (ALS) systems have long been used to provide digital topographic maps. Nowadays, Remote Sensing data are commonly used to create Digital Terrain Models (DTMs) for detailed urban-flood modelling. However, the difficulty of relying on top-view LiDAR data only is that it cannot detect whether passages for floodwaters are hidden underneath vegetated areas or beneath overarching structures such as roads, railroads, and bridges. Such (hidden) small urban features can play an important role in urban flood propagation. In this paper, a complex urban area of Kuala Lumpur, Malaysia was chosen as a study area to simulate the extreme flooding event that occurred in 2003. Three different DTMs were generated and used as input for a two-dimensional (2D) urban flood model. A top-view LiDAR approach was used to create two DTMs: (i) a standard LiDAR-DTM and (ii) a Filtered LiDAR-DTM taking into account specific ground-view features. In addition, a Structure from Motion (SfM) approach was used to detect hidden urban features from a sequence of ground-view images; these ground-view SfM data were then combined with top-view Filtered LiDAR data to create (iii) a novel Multidimensional Fusion of Views-Digital Terrain Model (MFV-DTM). These DTMs were then used as a basis for the 2D urban flood model. The resulting dynamic flood maps are compared with observations at six measurement locations. It was found that when applying only top-view DTMs as input data, the flood simulation results appear to have mismatches in both floodwater depths and flood propagation patterns. In contrast, when employing the top-ground-view fusion approach (MFV-DTM), the results not only show a good agreement in floodwater depth, but also simulate more correctly the floodwater dynamics around small urban feature. Overall, the new multi-view approach of combining top-view LiDAR data with ground-view SfM observations shows a good potential for creating an accurate digital terrain map which can be then used as an input for a numerical urban flood model.

  14. Above ground biomass estimation across forest types at different degradation levels in Central Kalimantan using LiDAR data

    Science.gov (United States)

    Kronseder, Karin; Ballhorn, Uwe; Böhm, Viktor; Siegert, Florian

    2012-08-01

    The quantification of tropical forest carbon stocks is a key challenge in creating a basic methodology for REDD (reducing emissions from deforestation and degradation in developing countries) projects. Small-footprint LiDAR (light detection and ranging) systems have proven to successfully correlate to above ground biomass (AGB) estimates in boreal and temperate forests. Their applicability to two different tropical rainforest types (lowland dipterocarp and peat swamp forest) in Central Kalimantan, Indonesia, was tested by developing multiple regression models at plot level using full waveform LiDAR point cloud characteristics. Forest inventory data is barely available for Central Kalimantan's forests. In order to sample a high number of field plots the angle count method was applied which allows fast sampling. More laborious fixed-area plots (three nests of circular shape) were used as a control and approved the use of the angle count method. AGB values, calculated by using existing allometric models, were in the range of 15-547 Mg ha-1 depending on forest type, degradation level and the model used for calculation. As expected, logging resulted in significant AGB losses in all forest types. AGB-prediction models were established for each forest type using statistical values of the LiDAR point clouds and the forest inventory plots. These regression models were then applied to six LiDAR tracks (altogether with a size of 5241 ha) covering unlogged, logged and burned lowland dipterocarp and peat swamp forest. The regression analysis showed that the 45th and 65th percentiles and the standard error of the mean explain 83% of the variation in lowland dipterocarp forest plots (RMSE = 21.37%). The best model for peat swamp forest could only explain 32% of the AGB variation (RMSE = 41.02%). Taking both forest types together explained 71% (RMSE = 33.85%). Calculating AGB for whole LiDAR tracks demonstrated the ability of this approach to quantify not only deforestation but also especially forest degradation and its spatial variability in terms of biomass change in different forest ecosystems using LiDAR transects. Concluding it can be stated that the combined approach of extensive field sampling and LiDAR point cloud analysis have high potential to significantly improve current estimates of carbon stocks across different forest types and degradation levels and its spatial variation in highly inaccessible tropical rainforests in the framework of REDD.

  15. ¿Quién es el dueño de la pantalla?

    Directory of Open Access Journals (Sweden)

    Juan Carlos Gómez Jaramillo

    2006-05-01

    Full Text Available A partir de 1990 la legislación colombiana ha tenido significativos avances para permitir que todas las personas puedan acceder a los servicios de telecomunicaciones, tal como corresponde en ejercicio del derecho fundamental del acceso a la información. Gracias al desarrollo de la tecnología, la limitación que generaba la necesidad de utilizar frecuencias radioeléctricas ya no es una razón válida desde el punto de vista constitucional para restringir el establecimiento de nuevos servicios y la difusión de información. Esta realidad técnica debe ser reconocida por el ordenamiento jurídico respecto de todos los servicios de telecomunicaciones. Dentro del actual marco constitucional no existe ningún fundamento para que los servicios que no utilicen frecuencias radioeléctricas sean objeto de reserva estatal. Este reconocimiento ya lo hizo el legislador al establecer que el servicio de telefonía pública básica conmutada local no sea objeto de concesión. En el mismo sentido, los medios masivos de comunicación, incluida la televisión, que no requieran el uso de frecuencias radioeléctricas y que puedan ser trasmitidos a través de redes de cable, gozan del derecho constitucional de establecerse libremente, aunque deben someterse a los reglamentos del servicio que establezca la autoridad competente. Las disposiciones legales que actualmente no permiten el ejercicio de tal derecho, son inconstitucionales. / Since 1990 Colombian telecommunication law has had significant advances allowing everybody access to telecommunication services in exercise of the fundamental right of information. Technology development permit that the limitation which generated the need of use frequencies, know days is not a valid reason -from a constitutional point of view- to restrict the operation of new telecommunication services and the information diffusion. This technical reality, have to be recognize in the legal order among all the telecommunication services. Colombian constitutional framework, does not has any rule that allow the restriction of telecom services which do not use frequencies under a "state reserve regime". Legal recognition in this sense, has been made by the legislator, when he established that the local telephony service does not required concession for its operation. In the same sense, massive media operators -including television operators- which do not use frequencies and which can be transmitted by wires, can be freely established observing only the specific service regulation dictated by the telecommunication authority. Legal dispositions that today do not allow the exercise of this constitutional right are illegal.

  16. LA EUTANASIA NO ES UN ACTO MÉDICO

    Scientific Electronic Library Online (English)

    Jorge, Merchán-Price.

    2008-06-01

    Full Text Available Neste artigo expõem-se os argumentos pelos quais o médico está juridicamente impedido de matar os seus pacientes. Dentre outras razões, os médicos não matam seus pacientes porque "matar" não é um ato médico terapêutico. Não restabelece a saúde nem preserva a vida. Se o Estado deseja a eutanásia e o [...] suicídio assistido, não existe nenhuma razão que impeça os familiares dos pacientes os levem ao cabo. Eles, não o médico, devem responder pelo ato ante a sociedade e as suas próprias consciências. Além disso, o artigo revisa de modo claro e conciso a sentencia C-239/97 da Corte Constitucional e explica porquê alguns artigos do projeto da lei 05/07 do Senado não se ajustam a ela e, portanto, são inconstitucionais. Abstract in spanish En este artículo se exponen los argumentos por los cuales el médico está jurídica y éticamente impedido para matar a sus pacientes. Entre otras razones, los médicos no matan a sus pacientes porque "matar" no es un acto médico terapéutico. No restablece la salud y tampoco preserva la vida. Si el Esta [...] do quiere la eutanasia y el suicidio asistido, no hay ninguna razón constitucional que impida realizar el acto eutanásico a los familiares de los pacientes enfermos. Son ellos, y no el médico, quienes deben responder ante la sociedad y ante sus propias conciencias por ello. El artículo, además, revisa de manera clara y precisa la sentencia C-239/97 de la Corte Constitucional, y explica por qué algunos artículos del proyecto de Ley 05/07 del Senado no se ajustan a ella y son, por tanto, inconstitucionales. Abstract in english This paper deals with the legal and moral reasons that prevent the physician from taking a patient's life. Among other reasons, medical doctors do not "kill" their patients because "killing" is not a therapeutic medical act. It does not reestablish the patient's previous state of health, nor does it [...] preserve life. If the state wants to allow euthanasia or assisted suicide, there is no constitutional reason why the relatives of a patient who is ill cannot euthanize or assist the patient in committing suicide. It is they, not the physician, who must answer to society and their own consciences for doing so. The article also offers a clear and precise look at Sentence C-239/97 issued by the Constitutional Court of Colombia and analyses the reasons why some of the articles in Senate Bill 05/07 are inconsistent with that sentence and, therefore, are unconstitutional.

  17. A methodology for quantifying volumetric changes at the Overlook pit of Kilauea Volcano using ground-based LiDAR

    Science.gov (United States)

    LeWinter, A. L.; Anderson, S. W.; Finnegan, D. C.; Patrick, M. R.; Orr, T. R.

    2013-12-01

    The shape of the Overlook pit, at the southeast edge of Kilauea Volcano's Halema'uma'u Crater, has evolved dramatically due to wall collapse and accretion of lava and tephra since its formation in March 2008. Contained within the pit is an active lava lake whose level fluctuates with changes in the summit magma reservoir and associated plumbing system. Quantifying the pit's topographical changes has been difficult due to the technical limitations of previous sensors and data processing, and the presence of a thick gas and ash plume that interferes with the emitted pulse and hampers the use of single-return LiDAR systems. In recent years, advancements in ground-based LiDAR scanners have enhanced our ability to capture topographic data in a diversity of volcanic settings at the highest spatial and temporal resolutions possible. Moreover, advancements in waveform digitization have significantly improved the acquisition of dense topographic data in environments where gas emissions have historically hampered efforts. Using LiDAR scanning, we developed a methodology that allows for the rapid and accurate measurement of the geometry of the Overlook pit and its lava lake during biannual LiDAR surveys throughout 2012 and 2013. Our research focuses on developing a methodology for quantifying volumetric changes between survey dates that is capable of differentiating between areas of fresh rock and tephra accretion and volume loss from the pit walls. Previously available methods for change detection capture only the net volume difference, whereas our approach allows us to successfully delineate both loss and gain. Though this study focuses on a cylindrical pit, our methodology may be applied in a variety of complex landscapes for rapid acquisition and processing of LiDAR data to monitor hazardous areas and identify topographical change.

  18. Improving the efficiency and accuracy of individual tree crown delineation from high-density LiDAR data

    Science.gov (United States)

    Hu, Baoxin; Li, Jili; Jing, Linhai; Judah, Aaron

    2014-02-01

    Canopy height model (CHM) derived from LiDAR (Light Detection And Ranging) data has been commonly used to generate segments of individual tree crowns for forest inventory and sustainable management. However, branches, tree crowns, and tree clusters usually have similar shapes and overlapping sizes, which cause current individual tree crown delineation methods to work less effectively on closed canopy, deciduous or mixedwood forests. In addition, the potential of 3-dimentional (3-D) LiDAR data is not fully realized by CHM-oriented methods. In this study, a framework was proposed to take advantage of the simplicity of a CHM-oriented method, detailed vertical structures of tree crowns represented in high-density LiDAR data, and any prior knowledge of tree crowns. The efficiency and accuracy of ITC delineation can be improved. This framework consists of five steps: (1) determination of dominant crown sizes; (2) generation of initial tree segments using a multi-scale segmentation method; (3) identification of “problematic” segments; (4) determination of the number of trees based on the 3-D LiDAR points in each of the identified segments; and (5) refinement of the “problematic” segments by splitting and merging operations. The proposed framework was efficient, since the detailed examination of 3-D LiDAR points was not applied to all initial segments, but only to those needed further evaluations based on prior knowledge. It was also demonstrated to be effective based on an experiment on natural forests in Ontario, Canada. The proposed framework and specific methods yielded crown maps having a good consistency with manual and visual interpretation. The automated method correctly delineated about 74% and 72% of the tree crowns in two plots with mixedwood and deciduous trees, respectively.

  19. Airborne LiDAR DEMs as a tool for deriving information on past glacier extent and ice flow

    Science.gov (United States)

    Seiser, Bernd; Fischer, Andrea

    2014-05-01

    The quantification of ice volumes and the identification of ice flow regimes within historical glacier systems are important steps towards understanding historical phases of glacier advance and disintegration in the context of Holocene climate fluctuation. Topographic LiDAR DEMs provide an excellent tool for gaining various kinds of spatially distributed information. Several case studies have been performed in the Austrian Alps, where LiDAR DEMs are available for almost the entire glacier area. LiDAR DEMs achieve vertical accuracies of few decimetres and can be used to calculate hillshade images with flat incidence angles, so that the surface structures of moraines and other glacial deposits can be identified. These hillshade images were used together with aerial photographs to identify the LIA (Little Ice Age) moraines and the elevation of the lateral moraines, so that, together with information on today's ice volume, a lower limit for the LIA ice volume could be calculated. The resulting LIA glacier areas showed good coincidence with former reconstructions based on field mapping and airborne photogrammetry. In addition to that, historical ice flow directions could be derived from the structure of basal moraines. These data allow an interpretation of the changing contribution of specific tributary glaciers to a joint glacier tongue, which may result in an important switch in ice dynamics leading to fast glacier advances recorded by frontal moraines. The combination of terrestrial long-term observations and LiDAR data documents the genesis of specific geomorphological features in the periglacial area by recording the processes occurring during the disintegration of glacier tongues. For example, the deposition of the material from former medial moraines in the newly formed periglacial area can be identified and quantified from the LiDAR data as well as debris flows or rock falls from the LIA moraines.

  20. Low-Density LiDAR and Optical Imagery for Biomass Estimation over Boreal Forest in Sweden

    Directory of Open Access Journals (Sweden)

    Iurii Shendryk

    2014-05-01

    Full Text Available Knowledge of the forest biomass and its change in time is crucial to understanding the carbon cycle and its interactions with climate change. LiDAR (Light Detection and Ranging technology, in this respect, has proven to be a valuable tool, providing reliable estimates of aboveground biomass (AGB. The overall goal of this study was to develop a method for assessing AGB using a synergy of low point density LiDAR-derived point cloud data and multi-spectral imagery in conifer-dominated forest in the southwest of Sweden. Different treetop detection algorithms were applied for forest inventory parameter extraction from a LiDAR-derived canopy height model. Estimation of AGB was based on the power functions derived from tree parameters measured in the field, while vegetation classification of a multi-spectral image (SPOT-5 was performed in order to account for dependences of AGB estimates on vegetation types. Linear regression confirmed good performance of a newly developed grid-based approach for biomass estimation (R2 = 0.80. Results showed AGB to vary from below 1 kg/m2 in very young forests to 94 kg/m2 in mature spruce forests, with RMSE of 4.7 kg/m2. These AGB estimates build a basis for further studies on carbon stocks as well as for monitoring this forest ecosystem in respect of disturbance and change in time. The methodology developed in this study can be easily adopted for assessing biomass of other conifer-dominated forests on the basis of low-density LiDAR and multispectral imagery. This methodology is hence of much wider applicability than biomass derivation based on expensive and currently still scarce high-density LiDAR data.

  1. ¿Qué es leer? ¿Qué es la lectura? What is to read? What is reading?

    Directory of Open Access Journals (Sweden)

    Elsa M. Ramírez Leyva

    2009-04-01

    Full Text Available El artículo se propone explorar lo que sostienen algunos pensadores de los campos de las humanidades y las ciencias sociales de la segunda mitad del siglo XX, en torno a interrogantes referentes a qué es leer y qué es la lectura. Paulo Freire, Roland Barthes, Michel de Certeau, Robert Escarpit, Noé Jitrik, Roger Chartier y Jorge Larrosa son autores en los que encontramos propuestas innovadoras fundadas en aparatos teóricos interdisciplinarios. Las coincidencias y divergencias, que sobre tan complejo tema encontramos en los autores citados, nos llevan a formular una propuesta conceptual desde la perspectiva bibliotecológica separada del discurso pedagógico, y se orienta a formar al ciudadano de la sociedad de la información y al de la industria editorial, ambos inmersos en nuevos modelos de consumo de la cultura escrita, e involucrados en la tecnología digital. En el contexto actual, la bibliotecología debe renovar su función social y uno de los aspectos fundamentales de dicha función es la problemática de la lectura, por lo que es indispensable abrir y explorar las teorías y métodos sobre ésta, en los que se basa el discurso y la práctica de la bibliotecología.The paper explores what is held by some authors of the second half of the 20th Century in the fields of humanities and social sciences, such as Paulo Freire, Roland Barthes, Michel de Certeau, Robert Escarpit, Noé Jitrik, Roger Chartier and Jorge Larrosa, among which we find innovative proposals based in theoretical interdisciplinary apparatuses. Coincidences and disagreements of these authors on such a complex matter lead us to formulate a conceptual answer from the library science perspective, which differs from the pedagogical discourse and points towards the education of the citizen of the information society and that of the publishing industry, both involved in digital technology. In today's context, library science must renew its social function and one of the fundamental aspects of this are the problematics of reading. Thus, reading methods and theories in which the discourse and practice of library science have been based up to now, must be opened and explored.

  2. ¿Qué es leer? ¿Qué es la lectura? / What is to read? What is reading?

    Scientific Electronic Library Online (English)

    Elsa M., Ramírez Leyva.

    2009-04-01

    Full Text Available SciELO Mexico | Language: Spanish Abstract in spanish El artículo se propone explorar lo que sostienen algunos pensadores de los campos de las humanidades y las ciencias sociales de la segunda mitad del siglo XX, en torno a interrogantes referentes a qué es leer y qué es la lectura. Paulo Freire, Roland Barthes, Michel de Certeau, Robert Escarpit, Noé [...] Jitrik, Roger Chartier y Jorge Larrosa son autores en los que encontramos propuestas innovadoras fundadas en aparatos teóricos interdisciplinarios. Las coincidencias y divergencias, que sobre tan complejo tema encontramos en los autores citados, nos llevan a formular una propuesta conceptual desde la perspectiva bibliotecológica separada del discurso pedagógico, y se orienta a formar al ciudadano de la sociedad de la información y al de la industria editorial, ambos inmersos en nuevos modelos de consumo de la cultura escrita, e involucrados en la tecnología digital. En el contexto actual, la bibliotecología debe renovar su función social y uno de los aspectos fundamentales de dicha función es la problemática de la lectura, por lo que es indispensable abrir y explorar las teorías y métodos sobre ésta, en los que se basa el discurso y la práctica de la bibliotecología. Abstract in english The paper explores what is held by some authors of the second half of the 20th Century in the fields of humanities and social sciences, such as Paulo Freire, Roland Barthes, Michel de Certeau, Robert Escarpit, Noé Jitrik, Roger Chartier and Jorge Larrosa, among which we find innovative proposals bas [...] ed in theoretical interdisciplinary apparatuses. Coincidences and disagreements of these authors on such a complex matter lead us to formulate a conceptual answer from the library science perspective, which differs from the pedagogical discourse and points towards the education of the citizen of the information society and that of the publishing industry, both involved in digital technology. In today's context, library science must renew its social function and one of the fundamental aspects of this are the problematics of reading. Thus, reading methods and theories in which the discourse and practice of library science have been based up to now, must be opened and explored.

  3. New late gene, dar, involved in the replication of bacteriophage T4 DNA. II. Overproduction of DNA binding protein (gene 32 protein) and further characterization

    International Nuclear Information System (INIS)

    We have previously shown that the arrested DNA synthesis of mutants defective in T4 phage gene 59 can be reversed by a mutation in dar. In this paper, we have examined the effect of the dar mutation on the kinetics of gene 32 protein (DNA binding protein) synthesis, DNA packaging, progeny formation, and several other processes. Several lines of evidence are presented showing that the regulation of synthesis of gene 32 protein is abnormal in dar1-infected cells. In these cells, gene 32 protein, an early protein, is also expressed late in the infectious cycle. Our data also indicate that the packaging of DNA into T4 phase heads is delayed in dar mutant-infected cells, and this in turn results in a 6- to 8-min delay in intracellular progeny formation, although the synthesis of late proteins appears to be normal, as shown by gel electrophoresis. We have also studied the phenotypes of the double mutant dar-amC5 (gene 59). The increased sensitivity to hydroxyurea caused by a mutation in the dar gene can be alleviated by a second mutation in gene 59, but an increased sensitivity to uv irradiation caused by a mutation in gene 59 cannot be alleviated by a second mutation in the dar gene. Therefore, the double mutant still exhibits abnormalities in the repair of uv lesions

  4. Genetic mapping of DArT markers in the Festuca-Lolium complex and their use in freezing tolerance association analysis.

    Science.gov (United States)

    Bartoš, Jan; Sandve, Simen Rød; Kölliker, Roland; Kopecký, David; Christelová, Pavla; Sto?es, St?pán; Ostrem, Liv; Larsen, Arild; Kilian, Andrzej; Rognli, Odd-Arne; Doležel, Jaroslav

    2011-04-01

    Species belonging to the Festuca-Lolium complex are important forage and turf species and as such, have been studied intensively. However, their out-crossing nature and limited availability of molecular markers make genetic studies difficult. Here, we report on saturation of F. pratensis and L. multiflorum genetic maps using Diversity Array Technology (DArT) markers and the DArTFest array.The 530 and 149 DArT markers were placed on genetic maps of L. multiflorum and F. pratensis, respectively, with overlap of 20 markers, which mapped in both species. The markers were sequenced and comparative sequence analysis was performed between L. multiflorum, rice and Brachypodium. The utility of the DArTFest array was then tested on a Festulolium population FuRs0357 in an integrated analysis using the DArT marker map positions to study associations between markers and freezing tolerance. Ninety six markers were significantly associated with freezing tolerance and five of these markers were genetically mapped to chromosomes 2, 4 and 7. Three genomic loci associated with freezing tolerance in the FuRs0357 population co-localized with chromosome segments and QTLs previously identified to be associated with freezing tolerance. The present work clearly confirms the potential of the DArTFest array in genetic studies of the Festuca-Lolium complex. The annotated DArTFest array resources could accelerate further studies and improvement of desired traits in Festuca-Lolium species. PMID:21212931

  5. Achieving Accuracy Requirements for Forest Biomass Mapping: A Data Fusion Method for Estimating Forest Biomass and LiDAR Sampling Error with Spaceborne Data

    Science.gov (United States)

    Montesano, P. M.; Cook, B. D.; Sun, G.; Simard, M.; Zhang, Z.; Nelson, R. F.; Ranson, K. J.; Lutchke, S.; Blair, J. B.

    2012-01-01

    The synergistic use of active and passive remote sensing (i.e., data fusion) demonstrates the ability of spaceborne light detection and ranging (LiDAR), synthetic aperture radar (SAR) and multispectral imagery for achieving the accuracy requirements of a global forest biomass mapping mission. This data fusion approach also provides a means to extend 3D information from discrete spaceborne LiDAR measurements of forest structure across scales much larger than that of the LiDAR footprint. For estimating biomass, these measurements mix a number of errors including those associated with LiDAR footprint sampling over regional - global extents. A general framework for mapping above ground live forest biomass (AGB) with a data fusion approach is presented and verified using data from NASA field campaigns near Howland, ME, USA, to assess AGB and LiDAR sampling errors across a regionally representative landscape. We combined SAR and Landsat-derived optical (passive optical) image data to identify forest patches, and used image and simulated spaceborne LiDAR data to compute AGB and estimate LiDAR sampling error for forest patches and 100m, 250m, 500m, and 1km grid cells. Forest patches were delineated with Landsat-derived data and airborne SAR imagery, and simulated spaceborne LiDAR (SSL) data were derived from orbit and cloud cover simulations and airborne data from NASA's Laser Vegetation Imaging Sensor (L VIS). At both the patch and grid scales, we evaluated differences in AGB estimation and sampling error from the combined use of LiDAR with both SAR and passive optical and with either SAR or passive optical alone. This data fusion approach demonstrates that incorporating forest patches into the AGB mapping framework can provide sub-grid forest information for coarser grid-level AGB reporting, and that combining simulated spaceborne LiDAR with SAR and passive optical data are most useful for estimating AGB when measurements from LiDAR are limited because they minimized forest AGB sampling errors by 15 - 38%. Furthermore, spaceborne global scale accuracy requirements were achieved. At least 80% of the grid cells at 100m, 250m, 500m, and 1km grid levels met AGB density accuracy requirements using a combination of passive optical and SAR along with machine learning methods to predict vegetation structure metrics for forested areas without LiDAR samples. Finally, using either passive optical or SAR, accuracy requirements were met at the 500m and 250m grid level, respectively.

  6. Genomic characterization of DArT markers based on high-density linkage analysis and physical mapping to the Eucalyptus genome

    OpenAIRE

    Petroli, Cesar D.; Sansaloni, Carolina P.; Carling, Jason; Steane, Dorothy A.; Vaillancourt, Rene E.; Myburg, Alexander Andrew; Da Silva Jr, Orzenil Bonfim; Pappas Jr, Georgios Joannis; Kilian, Andrzej; Grattapaglia, Dario

    2012-01-01

    Diversity Arrays Technology (DArT) provides a robust, high throughput, cost-effective method to query thousands of sequence polymorphisms in a single assay. Despite the extensive use of this genotyping platform for numerous plant species, little is known regarding the sequence attributes and genome-wide distribution of DArT markers. We investigated the genomic properties of the 7,680 DArT marker probes of a Eucalyptus array, by sequencing them, constructing a high density linkage map and carr...

  7. Object-Based Crop Species Classification Based on the Combination of Airborne Hyperspectral Images and LiDAR Data

    Directory of Open Access Journals (Sweden)

    Xiaolong Liu

    2015-01-01

    Full Text Available Identification of crop species is an important issue in agricultural management. In recent years, many studies have explored this topic using multi-spectral and hyperspectral remote sensing data. In this study, we perform dedicated research to propose a framework for mapping crop species by combining hyperspectral and Light Detection and Ranging (LiDAR data in an object-based image analysis (OBIA paradigm. The aims of this work were the following: (i to understand the performances of different spectral dimension-reduced features from hyperspectral data and their combination with LiDAR derived height information in image segmentation; (ii to understand what classification accuracies of crop species can be achieved by combining hyperspectral and LiDAR data in an OBIA paradigm, especially in regions that have fragmented agricultural landscape and complicated crop planting structure; and (iii to understand the contributions of the crop height that is derived from LiDAR data, as well as the geometric and textural features of image objects, to the crop species’ separabilities. The study region was an irrigated agricultural area in the central Heihe river basin, which is characterized by many crop species, complicated crop planting structures, and fragmented landscape. The airborne hyperspectral data acquired by the Compact Airborne Spectrographic Imager (CASI with a 1 m spatial resolution and the Canopy Height Model (CHM data derived from the LiDAR data acquired by the airborne Leica ALS70 LiDAR system were used for this study. The image segmentation accuracies of different feature combination schemes (very high-resolution imagery (VHR, VHR/CHM, and minimum noise fractional transformed data (MNF/CHM were evaluated and analyzed. The results showed that VHR/CHM outperformed the other two combination schemes with a segmentation accuracy of 84.8%. The object-based crop species classification results of different feature integrations indicated that incorporating the crop height information into the hyperspectral extracted features provided a substantial increase in the classification accuracy. The combination of MNF and CHM produced higher classification accuracy than the combination of VHR and CHM, and the solely MNF-based classification results. The textural and geometric features in the object-based classification could significantly improve the accuracy of the crop species classification. By using the proposed object-based classification framework, a crop species classification result with an overall accuracy of 90.33% and a kappa of 0.89 was achieved in our study area.

  8. Effects of the D1 dopamine receptor agonist dihydrexidine (DAR-0100A) on working memory in schizotypal personality disorder.

    Science.gov (United States)

    Rosell, Daniel R; Zaluda, Lauren C; McClure, Margaret M; Perez-Rodriguez, M Mercedes; Strike, K Sloan; Barch, Deanna M; Harvey, Philip D; Girgis, Ragy R; Hazlett, Erin A; Mailman, Richard B; Abi-Dargham, Anissa; Lieberman, Jeffrey A; Siever, Larry J

    2015-01-01

    Pharmacological enhancement of prefrontal D1 dopamine receptor function remains a promising therapeutic approach to ameliorate schizophrenia-spectrum working memory deficits, but has yet to be rigorously evaluated clinically. This proof-of-principle study sought to determine whether the active enantiomer of the selective and full D1 receptor agonist dihydrexidine (DAR-0100A) could attenuate working memory impairments in unmedicated patients with schizotypal personality disorder (SPD). We performed a randomized, double-blind, placebo-controlled trial of DAR-0100A (15?mg/150?ml of normal saline administered intravenously over 30?min) in medication-free patients with SPD (n=16) who met the criteria for cognitive impairment (ie, scoring below the 25th percentile on tests of working memory). We employed two measures of verbal working memory that are salient to schizophrenia-spectrum cognitive deficits, and that clinical data implicate as being associated with prefrontal D1 availability: (1) the Paced Auditory Serial Addition Test (PASAT); and (2) the N-back test (ratio of 2-back:0-back scores). Study procedures occurred over four consecutive days, with working memory testing on Days 1 and 4, and DAR-0100A/placebo administration on Days 2-4. Treatment with DAR-0100A was associated with significantly improved PASAT performance relative to placebo, with a very large effect size (Cohen's d=1.14). Performance on the N-back ratio was also significantly improved; however, this effect rested on both a non-significant enhancement and diminution of 2-back and 0-back performance, respectively; therefore interpretation of this finding is more complicated. DAR-0100A was generally well tolerated, with no serious medical or psychiatric adverse events; common side effects were mild to moderate and transient, consisting mainly of sedation, lightheadedness, tachycardia, and hypotension; however, we were able to minimize these effects, without altering the dose, with supportive measures, eg, co-administered normal saline. Although preliminary, these findings lend further clinical support to the potential of D1 receptor agonists to treat schizophrenia-spectrum working memory impairments. These data suggest a need for further studies with larger group sizes, serum DAR-0100A levels, and a more comprehensive neuropsychological battery. PMID:25074637

  9. Modelling Forest ?-Diversity and Floristic Composition — On the Added Value of LiDAR plus Hyperspectral Remote Sensing

    Directory of Open Access Journals (Sweden)

    Martin Wegmann

    2012-09-01

    Full Text Available The decline of biodiversity is one of the major current global issues. Still, there is a widespread lack of information about the spatial distribution of individual species and biodiversity as a whole. Remote sensing techniques are increasingly used for biodiversity monitoring and especially the combination of LiDAR and hyperspectral data is expected to deliver valuable information. In this study spatial patterns of vascular plant community composition and alpha-diversity of a temperate montane forest in Germany were analysed for different forest strata. The predictive power of LiDAR (LiD and hyperspectral (MNF datasets alone and combined (MNF+LiD was compared using random forest regression in a ten-fold cross-validation scheme that included feature selection and model tuning. The final models were used for spatial predictions. Species richness could be predicted with varying accuracy (R2 = 0.26 to 0.55 depending on the forest layer. In contrast, community composition of the different layers, obtained by multivariate ordination, could in part be modelled with high accuracies for the first ordination axis (R2 = 0.39 to 0.78, but poor accuracies for the second axis (R2 ? 0.3. LiDAR variables were the best predictors for total species richness across all forest layers (R2 LiD = 0.3, R2 MNF = 0.08, R2 MNF+LiD = 0.2, while for community composition across all forest layers both hyperspectral and LiDAR predictors achieved similar performances (R2 LiD = 0.75, R2 MNF = 0.76, R2 MNF+LiD = 0.78. The improvement in R2 was small (?0.07—if any—when using both LiDAR and hyperspectral data as compared to using only the best single predictor set. This study shows the high potential of LiDAR and hyperspectral data for plant biodiversity modelling, but also calls for a critical evaluation of the added value of combining both with respect to acquisition costs.

  10. Estimation Of Landslide Processes And Slope Evolution From LiDAR-Derived DEMs

    Science.gov (United States)

    Kasai, M.; Ikeda, M.; Asahina, T.; Fujisawa, K.

    2007-12-01

    LiDAR-derived DEMs are making an increasing contribution towards landslide hazard mitigation owing to their increasing availability. They not only produce detailed contour maps and visualized images to create more accurate and complete landslide inventories, but also can be analyzed to understand the surface process of landslides with the notion that their activity relates to fine-scale surface roughness. At present, surface fabric filtering of these DEMs has been used to examine individual landslides, although landslide processes can be better understood when they are considered as a part of hillslope evolution of the area of interest. This presentation introduces the work that the eigenvalue ratio, which represents the 3-dimensional surface roughness, can be used to analyze landslide processes and their influence on hillslope evolution. A case study is presented from a 5 km2 steep (average slope = 36 %) area of Kii Peninsula, Japan, where a 1-m grid LiDAR-derived DEM was used to derive eigenvalue ratios and related terrain attributes. The slopes of the v- shaped valleys are particularly landslide-prone and there is little valley margin except for occasional terraces along the river. Based on a combination of the eigenvalue ratio and field survey, the slopes of the study area were categorized into 4 principal types. Slopes with a filter value of less than 2.50 (roughest) are bedrock-dominant, while those between 2.50 and 2.75 partly represent surface collapses and loosened bedrock, and those between 2.75 and 3.00 are colluvial slopes with large rock materials. Where the value exceeds 3.00 the slopes are inactive or covered with fine colluvial materials. The results imply that more attention should be paid to landslide blocks with a filter value of between 2.50 and 2.75, e.g. by continuous monitoring, as they are at higher risk of entire slope collapse in the near future. The eigenvalue ratio tends to increase and the terrain becomes smoother uphill, indicating that slopes evolve by losing stability from the valley floor. The blocks with a value between 2.75 and 3.00 may in future gain similar slope features to those with a value between 2.50 and 2.75, although how long this transition takes is uncertain. The process has probably been driven by the river eroding the base of hillslopes and striping away earth at high flows. The results suggest that, not only can the current activity of landslides be evaluated, but also their future behavior can be estimated by applying surface fabric filters to an area of interest and considering their spatial distribution. Together with creating detailed landslide inventories, utilizing LiDAR-derived DEMs in this manner will in future contribute to the planning of landslide hazard mitigation programs.

  11. LiDAR-based characterization of the Mt Shasta debris avalanche deposit

    Science.gov (United States)

    Tortini, R.; Carn, S. A.; van Wyk de Vries, B.

    2013-12-01

    The failure of destabilized volcano flanks, due either to tectonic activity on basement structures underlying the volcanic edifice, magmatic intrusion or external forcing (e.g. weather events), is a likely occurrence during the lifetime of a stratovolcano. Flank failure can generate large debris avalanches, and the significant hazards associated with volcanic debris avalanches in the Cascade range were demonstrated by the collapse of Mt St Helens (WA, USA), which triggered its devastating explosive eruption in May 1980. Mt Shasta is a 4,317 m high, snow-capped, steep-sloped stratovolcano located in Northern California. The most voluminous of the Cascade volcanoes, the current edifice began forming on the remnants of an ancestral Mt Shasta that collapsed approximately 300,000 to 380,000 years ago producing one of the largest debris avalanches known on Earth. The debris avalanche deposit (DAD) covers a surface of 450 km2 across the Shasta valley, for a total volume of approximately 26 km3. A LiDAR point cloud and orthophoto of the Shasta DAD surveyed by the NCALM consortium provides a new topographic dataset of the area with unprecedented resolution. This will permit the identification of subtle topographic features of the Shasta DAD not apparent in the field or in coarser resolution datasets. Statistical measures of the LiDAR-derived digital elevation model, such as surface texture, will be used to detect and characterize the hummock topography, differentiate between various DAD facies and geomorphic units, and extract the morphological parameters for subsequent analogue and numerical modeling of the debris avalanche. This work aims to improve our understanding of the Mt Shasta DAD morphology and its dynamics, and provide insight into the cause, timing of events and mode of emplacement of the DAD. The Cascade range includes numerous large extinct, dormant or active stratovolcanoes, and knowledge of the link between basement structures and the Mt Shasta DAD will elucidate the causes of edifice instability and may be used to target priority areas for volcanic hazard mapping.

  12. Geomorphic mapping of the southern Maacama fault based on LiDAR data

    Science.gov (United States)

    Hoeft, J. S.; Sowers, J. M.; Kelsey, H. M.; Prentice, C. S.; Frankel, K. L.

    2008-12-01

    The Maacama fault is an active strike slip fault, and a potentially significant seismic source, within the San Andreas transform system. The fault is located east of and parallel to the San Andreas fault in Sonoma and Mendocino counties, California and is divided into a northern and southern section based on a NW to NNW change in strike. The southern segment comprises 54 km of the fault's 144 km total length and is primarily located in an upland area traversing mountainous terrain. Strain is thought to transfer northward from the East Bay fault zone along the Rodgers Creek fault and, through a right step, to the Maacama fault. LiDAR data collected in a 1-km-wide swath along the southern Maacama fault, as part of the GeoEarthscope project, were used to produce a bare-earth digital elevation model, from which hillshade, topographic contour, slope, and curvature maps with 0.5- to 1-m-resolution were derived. Mapping was primarily conducted digitally in a GIS environment, and interpretation of LiDAR data was supplemented with aerial photograph interpretation and field inspection. Primary, Holocene-age fault-related geomorphic features, consisting of scarps and dextrally offset drainages, define the southern Maacama. These features are sparsely distributed and comprise less than 20% of the fault length. The fault scarps define a sequence of left-stepping, en echelon fault segments with an average segment length of 230 m. By contrast, the northern Maacama fault is better defined geomorphically. The poor expression of the southern Maacama is likely due to the presence of active hillslope processes and low levels of seismicity. Seismicity along the southern segment is lower than that of the northern segment. The Coast Range uplands, primarily composed of Franciscan Complex, is characterized by numerous landslides and experiences annual precipitation of 75 to 180 cm. There is approximately 30 km of overlap between the northern end of the Rodgers Creek fault and the southern extent of the Maacama fault, and in this region the Rodgers Creek fault is better expressed geomorphically. Because climate and lithology are similar across this region, we attribute the stark differences in geomorphic appearance to tectonic activity. This difference suggests that over Holocene and late Pleistocene timescales, strain has been preferentially accommodated along the Rodgers Creek fault and is gradually transferred northward to the Maacama fault.

  13. A Decade Remote Sensing River Bathymetry with the Experimental Advanced Airborne Research LiDAR

    Science.gov (United States)

    Kinzel, P. J.; Legleiter, C. J.; Nelson, J. M.; Skinner, K.

    2012-12-01

    Since 2002, the first generation of the Experimental Advanced Airborne Research LiDAR (EAARL-A) sensor has been deployed for mapping rivers and streams. We present and summarize the results of comparisons between ground truth surveys and bathymetry collected by the EAARL-A sensor in a suite of rivers across the United States. These comparisons include reaches on the Platte River (NE), Boise and Deadwood Rivers (ID), Blue and Colorado Rivers (CO), Klamath and Trinity Rivers (CA), and the Shenandoah River (VA). In addition to diverse channel morphologies (braided, single thread, and meandering) these rivers possess a variety of substrates (sand, gravel, and bedrock) and a wide range of optical characteristics which influence the attenuation and scattering of laser energy through the water column. Root mean square errors between ground truth elevations and those measured by the EAARL-A ranged from 0.15-m in rivers with relatively low turbidity and highly reflective sandy bottoms to over 0.5-m in turbid rivers with less reflective substrates. Mapping accuracy with the EAARL-A has proved challenging in pools where bottom returns are either absent in waveforms or are of such low intensity that they are treated as noise by waveform processing algorithms. Resolving bathymetry in shallow depths where near surface and bottom returns are typically convolved also presents difficulties for waveform processing routines. The results of these evaluations provide an empirical framework to discuss the capabilities and limitations of the EAARL-A sensor as well as previous generations of post-processing software for extracting bathymetry from complex waveforms. These experiences and field studies not only provide benchmarks for the evaluation of the next generation of bathymetric LiDARs for use in river mapping, but also highlight the importance of developing and standardizing more rigorous methods to characterize substrate reflectance and in-situ optical properties at study sites. They also point out the continued necessity of ground truth data for algorithm refinement and survey verification.

  14. Reduction of DTM obtained from LiDAR data for flood modeling

    Science.gov (United States)

    Baku?a, K.

    2011-12-01

    Recent years the cataclysm of flood has occurred in many regions around the world. For this reason, so much attention is focused on prediction of this cataclysm by creating flood risk maps and hydrodynamic - numerical simulation of flood water which are based on Digital Terrain Model (DTM). The modern techniques for automatic data acquisition provide very abundant amount of points. Actually, Light Detection and Ranging (LiDAR) is the most effective data source for DTM creation with density of one to few points per square meter and good height accuracy of less than 15 cm. This high redundancy of data is essential problem for algorithms used in programs for flood modeling. Many software generating such models are restricted with respect to the maximum number of points in DTM. Hundreds of thousands of points are too large number for complex calculations which describe fluid model of the flood water. In order to obtain reliable and accurate results, it is necessary to have DTM with an appropriate accuracy. The flood disaster also occurs in large areas what usually is associated with large data sets. However, it is possible to provide suitable DTM for flood modeling by its generalization without losing its accuracy, which could still ensure sufficient precision for hydrodynamic - numerical calculations. In this paper six reduction algorithms were tested to obtain DTM with small number of points and with accuracy comparable to the original model created from LiDAR data. The main criteria for this comparison was the relation between accuracy and reduction coefficient of final result. Methods used in this research were based on different DTM structures. GRID, TIN and hierarchical structures were compared in various approaches to obtain the most reduced and the most accurate terrain model of two study areas. As the result of the experiment the best methods for data reduction were chosen. Over 90% reduction rate and less than 20 cm root mean standard error were achieved in practice for different types of terrain with respect to input DTM. It was noted that hybrid and quad-tree grid based models can be even more efficient than a typical uniform GRID or TIN one.

  15. Urban Vegetation Mapping from Fused Hyperspectral Image and LiDAR Data with Application to Monitor Urban Tree Heights

    Directory of Open Access Journals (Sweden)

    Fatwa Ramdani

    2013-07-01

    Full Text Available Urban vegetations have infinite proven benefits for urban inhabitants including providing shade, improving air quality, and enhancing the look and feel of communities. But creating a complete inventory is a time consuming and resource intensive process. The extraction of urban vegetation is a challenging task, especially to monitor the urban tree heights. In this study we present an efficient extraction method for mapping and monitoring urban tree heights using fused hyperspectral image and LiDAR data. Endmember distribution mapping using the spectral angle mapper technique is employed in this study. High convenience results achieved using fused hyperspectral and LiDAR data from this semiautomatics technique. This method could enable urban community organizations or local governments to map and monitor urban’s tree height and its spatial distribution.

  16. Quantification, analysis and modelling of soil erosion on steep slopes using LiDAR and UAV photographs

    Science.gov (United States)

    Neugirg, F.; Kaiser, A.; Schmidt, J.; Becht, M.; Haas, F.

    2015-03-01

    Steep hill slopes in the Bavarian Alps and at an artificial waste dump on the Island of Elba are subject to soil erosion through geomorphological processes. Long-term high-resolution terrestrial LiDAR data are available and have been analysed for both areas. The analysis indicated different erosion patterns on the slopes that could be the result of different geomorphological processes. Additionally, both study sites show a good agreement between the annual erosion rates and the size of the hydrological catchment as a proxy for the sediment contributing area. The results presented in this study represent the first analysis of hill slope erosion measured with LiDAR and UAV systems. The hill slope erosion will be subject to measurements using a higher temporal resolution during future years in order to identify different erosion processes throughout the annual time step.

  17. Evaluations of Three-Dimensional Building Model Reconstruction from LiDAR Point Clouds and Single-View Perspective Imagery

    Science.gov (United States)

    Tsai, F.; Chang, H.

    2014-06-01

    This paper briefly presents two approaches for effective three-dimensional (3D) building model reconstruction from terrestrial laser scanning (TLS) data and single perspective view imagery and assesses their applicability to the reconstruction of 3D models of landmark or historical buildings. The collected LiDAR point clouds are registered based on conjugate points identified using a seven-parameter transformation system. Three dimensional models are generated using plan and surface fitting algorithms. The proposed single-view reconstruction (SVR) method is based on vanishing points and single-view metrology. More detailed models can also be generated according to semantic analysis of the façade images. Experimental results presented in this paper demonstrate that both TLS and SVR approaches can successfully produce accurate and detailed 3D building models from LiDAR point clouds or different types of single-view perspective images.

  18. What is the effect of LiDAR-derived DEM resolution on large-scale watershed model results?

    Energy Technology Data Exchange (ETDEWEB)

    Ping Yang; Daniel B. Ames; Andre Fonseca; Danny Anderson; Rupesh Shrestha; Nancy F. Glenn; Yang Cao

    2014-08-01

    This paper examines the effect of raster cell size on hydrographic feature extraction and hydrological modeling using LiDAR derived DEMs. LiDAR datasets for three experimental watersheds were converted to DEMs at various cell sizes. Watershed boundaries and stream networks were delineated from each DEM and were compared to reference data. Hydrological simulations were conducted and the outputs were compared. Smaller cell size DEMs consistently resulted in less difference between DEM-delineated features and reference data. However, minor differences been found between streamflow simulations resulted for a lumped watershed model run at daily simulations aggregated at an annual average. These findings indicate that while higher resolution DEM grids may result in more accurate representation of terrain characteristics, such variations do not necessarily improve watershed scale simulation modeling. Hence the additional expense of generating high resolution DEM's for the purpose of watershed modeling at daily or longer time steps may not be warranted.

  19. Fusion of High Resolution Aerial Multispectral and LiDAR Data: Land Cover in the Context of Urban Mosquito Habitat

    OpenAIRE

    Leeuwen, Willem J. D.; Hartfield, Kyle A.; Landau, Katheryn I.

    2011-01-01

    Remotely sensed multi-spectral and -spatial data facilitates the study of mosquito-borne disease vectors and their response to land use and cover composition in the urban environment. In this study we assess the feasibility of integrating remotely sensed multispectral reflectance data and LiDAR (Light Detection and Ranging)-derived height information to improve land use and land cover classification. Classification and Regression Tree (CART) analyses were used to compare and contrast the enha...

  20. Genetic structure, linkage disequilibrium and signature of selection in Sorghum: lessons from physically anchored DArT markers.

    Science.gov (United States)

    Bouchet, Sophie; Pot, David; Deu, Monique; Rami, Jean-François; Billot, Claire; Perrier, Xavier; Rivallan, Ronan; Gardes, Laëtitia; Xia, Ling; Wenzl, Peter; Kilian, Andrzej; Glaszmann, Jean-Christophe

    2012-01-01

    Population structure, extent of linkage disequilibrium (LD) as well as signatures of selection were investigated in sorghum using a core sample representative of worldwide diversity. A total of 177 accessions were genotyped with 1122 informative physically anchored DArT markers. The properties of DArTs to describe sorghum genetic structure were compared to those of SSRs and of previously published RFLP markers. Model-based (STRUCTURE software) and Neighbor-Joining diversity analyses led to the identification of 6 groups and confirmed previous evolutionary hypotheses. Results were globally consistent between the different marker systems. However, DArTs appeared more robust in terms of data resolution and bayesian group assignment. Whole genome linkage disequilibrium as measured by mean r(2) decreased from 0.18 (between 0 to 10 kb) to 0.03 (between 100 kb to 1 Mb), stabilizing at 0.03 after 1 Mb. Effects on LD estimations of sample size and genetic structure were tested using i. random sampling, ii. the Maximum Length SubTree algorithm (MLST), and iii. structure groups. Optimizing population composition by the MLST reduced the biases in small samples and seemed to be an efficient way of selecting samples to make the best use of LD as a genome mapping approach in structured populations. These results also suggested that more than 100,000 markers may be required to perform genome-wide association studies in collections covering worldwide sorghum diversity. Analysis of DArT markers differentiation between the identified genetic groups pointed out outlier loci potentially linked to genes controlling traits of interest, including disease resistance genes for which evidence of selection had already been reported. In addition, evidence of selection near a homologous locus of FAR1 concurred with sorghum phenotypic diversity for sensitivity to photoperiod. PMID:22428056

  1. Sensitivity Analysis of 3D Individual Tree Detection from LiDAR Point Clouds of Temperate Forests

    Directory of Open Access Journals (Sweden)

    Wei Yao

    2014-05-01

    Full Text Available Light detection and ranging (LiDAR sampling or full-area coverage is deemed as favorable means to achieve timely and robust characterizations of forests. Recently, a 3D segmentation approach was developed for extracting single trees from LiDAR data. However, key parameters for modules used in the strategy had to be empirically determined. This paper highlights a comprehensive study for the sensitivity analysis of 3D single tree detection from airborne LiDAR data. By varying key parameters, their influences on results are to be quantified. The aim of the study is to enlighten the optimal combination of parameter values towards new applications. For the experiment, a number of sample plots from two temperate forest sites in Europe were selected. LiDAR data with a point density of 25 pts/m2 over the first site in the Bavarian forest national park were captured with under both leaf-on and leaf-off conditions. Moreover, a Riegl scanner was used to acquire data over the Austrian Alps forest with four-fold point densities of 5 pts/m2, 10 pts/m2, 15 pts/m2 and 20 pts/m2, respectively, under leaf-off conditions. The study results proved the robustness and efficiency of the 3D segmentation approach. Point densities larger than 10 pts/m2 did not seem to significantly contribute to the improvement in the performance of 3D tree detection. The performance of the approach can be further examined and improved by optimizing the parameter settings with respect to different data properties and forest structures.

  2. The Application of LiDAR to Assessment of Rooftop Solar Photovoltaic Deployment Potential in a Municipal District Unit

    OpenAIRE

    Gerald Barber; Rob Harrap; Nguyen, Ha T.; Pearce, Joshua M.

    2012-01-01

    A methodology is provided for the application of Light Detection and Ranging (LiDAR) to automated solar photovoltaic (PV) deployment analysis on the regional scale. Challenges in urban information extraction and management for solar PV deployment assessment are determined and quantitative solutions are offered. This paper provides the following contributions: (i) a methodology that is consistent with recommendations from existing literature advocating the integration of cross-disciplinary com...

  3. Integrating airborne LiDAR dataset and photographic images towards the construction of 3D building model

    Science.gov (United States)

    Idris, R.; Latif, Z. A.; Hamid, J. R. A.; Jaafar, J.; Ahmad, M. Y.

    2014-02-01

    A 3D building model of man-made objects is an important tool for various applications such as urban planning, flood mapping and telecommunication. The reconstruction of 3D building models remains difficult. No universal algorithms exist that can extract all objects in an image successfully. At present, advances in remote sensing such as airborne LiDAR (Light Detection and Ranging) technology have changed the conventional method of topographic mapping and increased the interest of these valued datasets towards 3D building model construction. Airborne LiDAR has proven accordingly that it can provide three dimensional (3D) information of the Earth surface with high accuracy. In this study, with the availability of open source software such as Sketch Up, LiDAR datasets and photographic images could be integrated towards the construction of a 3D building model. In order to realize the work an area comprising residential areas situated at Putrajaya in the Klang Valley region, Malaysia, covering an area of two square kilometer was chosen. The accuracy of the derived 3D building model is assessed quantitatively. It is found that the difference between the vertical height (z) of the 3D building models derived from LiDAR dataset and ground survey is approximately ± 0.09 centimeter (cm). For the horizontal component (RMSExy), the accuracy estimates derived for the 3D building models were ± 0.31m. The result also shows that the qualitative assessment of the 3D building models constructed seems feasible for the depiction in the standard of LOD 3 (Level of details).

  4. LiDAR observations of an Earth magmatic plumbing system as an analog for Venus and Mars distributed volcanism

    Science.gov (United States)

    Richardson, Jacob; Connor, Charles; Malservisi, Rocco; Bleacher, Jacob; Connor, Laura

    2014-05-01

    Clusters of tens to thousands of small volcanoes (diameters generally LiDAR) can identify volcanic units (sills, dikes, and conduits) at high resolution, both geomorphologically and with near infrared return intensity values. Two Terrestrial LiDAR Surveys and an Airborne LiDAR Survey have been carried out over the San Rafael volcanic swarm, producing a three dimensional point cloud over approximately 36 sq. km. From the point clouds of these surveys, 1-meter DEMs are produced and volcanic intrusions have been mapped. Here we present reconstructions of the volcanic instrusions of the San Rafael Swarm. We create this reconstruction by extrapolating mapped intrustions from the LiDAR surveys into a 3D space around the current surface. We compare the estimated intrusive volume to the estimated conduit density and estimates of extrusive volume at volcano clusters of similar density. The extrapolated reconstruction and conduit mapping provide a first-order estimate of the final intrustive/extrusive volume ratio for the now eroded volcanic field. Earth, Venus and Mars clusters are compared using Kernel Density Estimation (KDE) , which objectively compares cluster area, complexity, and vent density per sq. km. We show that Martian clusters are less dense than Venus clusters, which in turn are less dense than those on Earth. KDE and previous models of intrusive morphology for Mars and Venus are here used to calibrate the San Rafael plumbing system model to clusters on the two planets. The results from the calibrated Mars and Venus plumbing system models can be compared to previous estimates of magma budget and intrusive/extrusive ratios on Venus and Mars.

  5. Genetic Diversity and Population Structure of Tetraploid Wheats (Triticum turgidum L.) Estimated by SSR, DArT and Pedigree Data

    OpenAIRE

    Laido?, Giovanni; Mangini, Giacomo; Taranto, Francesca; Gadaleta, Agata; Blanco, Antonio; Cattivelli, Luigi; Marone, Daniela; Mastrangelo, Anna M.; Papa, Roberto; Vita, Pasquale

    2013-01-01

    Levels of genetic diversity and population genetic structure of a collection of 230 accessions of seven tetraploid Triticum turgidum L. subspecies were investigated using six morphological, nine seed storage protein loci, 26 SSRs and 970 DArT markers. The genetic diversity of the morphological traits and seed storage proteins was always lower in the durum wheat compared to the wild and domesticated emmer. Using Bayesian clustering (K?=?2), both of the sets of molecular markers distinguish...

  6. An energy minimization approach to automated extraction of regular building footprints from airborne LiDAR data

    Science.gov (United States)

    He, Y.; Zhang, C.; Fraser, C. S.

    2014-08-01

    This paper presents an automated approach to the extraction of building footprints from airborne LiDAR data based on energy minimization. Automated 3D building reconstruction in complex urban scenes has been a long-standing challenge in photogrammetry and computer vision. Building footprints constitute a fundamental component of a 3D building model and they are useful for a variety of applications. Airborne LiDAR provides large-scale elevation representation of urban scene and as such is an important data source for object reconstruction in spatial information systems. However, LiDAR points on building edges often exhibit a jagged pattern, partially due to either occlusion from neighbouring objects, such as overhanging trees, or to the nature of the data itself, including unavoidable noise and irregular point distributions. The explicit 3D reconstruction may thus result in irregular or incomplete building polygons. In the presented work, a vertex-driven Douglas-Peucker method is developed to generate polygonal hypotheses from points forming initial building outlines. The energy function is adopted to examine and evaluate each hypothesis and the optimal polygon is determined through energy minimization. The energy minimization also plays a key role in bridging gaps, where the building outlines are ambiguous due to insufficient LiDAR points. In formulating the energy function, hard constraints such as parallelism and perpendicularity of building edges are imposed, and local and global adjustments are applied. The developed approach has been extensively tested and evaluated on datasets with varying point cloud density over different terrain types. Results are presented and analysed. The successful reconstruction of building footprints, of varying structural complexity, along with a quantitative assessment employing accurate reference data, demonstrate the practical potential of the proposed approach.

  7. Light Detection and Ranging (LiDAR) and Multispectral Scanner (MSS) Studies Examine Coastal Environments Influenced by Mining

    OpenAIRE

    Charles Kerfoot, W.; Hobmeier, Martin M.; Foad Yousef; Green, Sarah A.; Robert Regis; Brooks, Colin N.; Robert Shuchman; Jamey Anderson; Molly Reif

    2014-01-01

    There are numerous examples of past and present mine disposal into freshwater and marine coastal bays and riverine environments. Due to its high spatial resolution and extended water penetration, coastal light detection and ranging (LiDAR), coupled with multispectral scanning (MSS), has great promise for resolving disturbed shoreline features in low turbidity environments. Migrating mine tailings present serious issues for Lake Superior and coastal marine environments. Previous investigations...

  8. Monitoring changes in the Platte River riparian corridor with serial LiDAR surveys

    Science.gov (United States)

    Kinzel, Paul J.; Nelson, Jonathan M.; Wright, C. Wayne

    2006-01-01

    The Platte River in central Nebraska is a wide, sand-bedded river that provides habitat for migratory water birds along the North American flyway. The central Platte River functions as critical habitat for the endangered whooping crane (Grus americana) and also is an important habitat for the endangered least tern (Sterna antillarum) and the threatened piping plover (Charadrius melodus). Upstream water-resource development over the last century has decreased the water and sediment supplied to the central Platte River. This has resulted in vegetation encroachment and narrowing of Platte River channels. The National Academy of Sciences' National Research Council, in a recent review of these critical habitat designations, concluded that the current morphology of Platte River channels is limiting the recovery of the endangered and threatened avian species. Habitat-enhancement efforts along the Platte River currently (2006) are focused on the clearing of vegetation from in-channel and riparian areas, whereas future plans propose the release of water from upstream dams as a means to prevent vegetation from encroaching on the active river channel. For this reason, monitoring the physical response of the river channel to these management treatments is an important component of a proposed habitat recovery program. Understanding the effects of management strategies on Platte River riparian habitat also is a key objective of the U.S. Geological Survey's Platte River Priority Ecosystem Program (http://mcmcweb.er.usgs.gov/platte/). This fact sheet describes applications of LiDAR to monitor changes in the Platte River riparian corridor.

  9. Using airborne LiDAR to investigated the bedrock incision in the Tsaoling Landslide surface, Taiwan

    Science.gov (United States)

    Hou, Chin-Shyong; Chen, Yi-Zhong; Hsieh, Yu-Chung; Chen, Rou-Fei; Wu, Ruo-Ying

    2014-05-01

    In recent decades, a great number of studies have investigated the tectonic topographic evolution and development of active orogenic belts that cause the dynamics related to a variety of terrain features. In particular, the incision of bedrock via erosion by rivers plays a crucial research role. Erosion gullies reflect the incision of bedrock by rivers during the tectonic and topographic evolution of active orogenic zones; however, a limited amount of measurement data is currently available. Therefore, this study explored the incision erosion rate of different lithologies in the collapsed surface of a landslide induced by the 1999 Chi-chi earthquake in the Tsaoling area. This study uses the 1 m high-resolution DEM established by the Central Geological Survey via airborne LiDAR, organized by the Ministry of Economic Affairs (MOEA. In this study, we investigated the distribution of erosion gullies produced in different rock formations by the Tsaoling landslide based on an openness analysis using a red relief image map (RRIM) and calculated the bedrock incision rate for the Cholan Formation and Chishui Shale for 1999, 2011 and 2012, which was 30-40 cm/yr and 54-90 cm/yr on average, respectively. These results indicated that the Cholan Formation has a higher resistance to erosion than the Chishui Shale, where the erosion was more serious.

  10. Modeling spatiotemporal patterns of understory light intensity using airborne laser scanner (LiDAR)

    Science.gov (United States)

    Peng, Shouzhang; Zhao, Chuanyan; Xu, Zhonglin

    2014-11-01

    This study described a spatiotemporally explicit 3D raytrace model to provide spatiotemporal patterns of understory light (light intensity in the forest floor and along the vertical gradient). The model was built based on voxels derived from LiDAR and field investigation data, geographical information (elevation and location), and solar position (azimuth and altitude angles). We calculated the distance (L, in meters) traveled by solar ray in the crowns based on the model, and then calibrated and verified the light attenuation function using L based on Beer's law. L and the ratio of below canopy light intensity to above canopy light intensity showed obviously exponential relationship, with R2 = 0.94 and P mapped with the respect to the solar position, and these patterns represented the variations in the forest-shaded area. The spatial patterns of the light intensity along vertical gradient were also mapped, and they showed strong variations. We concluded that L could account for the complex patterns of understory light environment with respect to the geographical and solar position variations. The 3D raytrace model can be integrated with ecological or hydrological models to resolve several issues, such as plant succession and competition, soil evaporation, plant transpiration, and snowmelt in the forest.

  11. Taking Stock of Circumboreal Forest Carbon With Ground Measurements, Airborne and Spaceborne LiDAR

    Science.gov (United States)

    Neigh, Christopher S. R.; Nelson, Ross F.; Ranson, K. Jon; Margolis, Hank A.; Montesano, Paul M.; Sun, Guoqing; Kharuk, Viacheslav; Naesset, Erik; Wulder, Michael A.; Andersen, Hans-Erik

    2013-01-01

    The boreal forest accounts for one-third of global forests, but remains largely inaccessible to ground-based measurements and monitoring. It contains large quantities of carbon in its vegetation and soils, and research suggests that it will be subject to increasingly severe climate-driven disturbance. We employ a suite of ground-, airborne- and space-based measurement techniques to derive the first satellite LiDAR-based estimates of aboveground carbon for the entire circumboreal forest biome. Incorporating these inventory techniques with uncertainty analysis, we estimate total aboveground carbon of 38 +/- 3.1 Pg. This boreal forest carbon is mostly concentrated from 50 to 55degN in eastern Canada and from 55 to 60degN in eastern Eurasia. Both of these regions are expected to warm >3 C by 2100, and monitoring the effects of warming on these stocks is important to understanding its future carbon balance. Our maps establish a baseline for future quantification of circumboreal carbon and the described technique should provide a robust method for future monitoring of the spatial and temporal changes of the aboveground carbon content.

  12. Recovery of Forest Canopy Parameters by Inversion of Multispectral LiDAR Data

    Directory of Open Access Journals (Sweden)

    Andrew Wallace

    2012-02-01

    Full Text Available We describe the use of Bayesian inference techniques, notably Markov chain Monte Carlo (MCMC and reversible jump MCMC (RJMCMC methods, to recover forest structural and biochemical parameters from multispectral LiDAR (Light Detection and Ranging data. We use a variable dimension, multi-layered model to represent a forest canopy or tree, and discuss the recovery of structure and depth profiles that relate to photochemical properties. We first demonstrate how simple vegetation indices such as the Normalized Differential Vegetation Index (NDVI, which relates to canopy biomass and light absorption, and Photochemical Reflectance Index (PRI which is a measure of vegetation light use efficiency, can be measured from multispectral data. We further describe and demonstrate our layered approach on single wavelength real data, and on simulated multispectral data derived from real, rather than simulated, data sets. This evaluation shows successful recovery of a subset of parameters, as the complete recovery problem is ill-posed with the available data. We conclude that the approach has promise, and suggest future developments to address the current difficulties in parameter inversion.

  13. Spatial Estimates of GPP Using LiDAR- and Quickbird-Derived fPAR

    Science.gov (United States)

    Cook, B. D.; Bolstad, P. V.; Naesset, E.; Heinsch, F. A.; Anderson, R. S.; Garrigues, S.; Morisette, J. T.; Nickeson, J. E.; Hilton, T. W.; Davis, K. J.; Roman, M. O.

    2007-12-01

    Regional- to global-scale gross primary production (GPP) is commonly estimated with light-use efficiency models, which are largely dependent on remotely sensed estimates of the fraction of photosynthetically active radiation absorbed by vegetation (fPAR). Methodologies to quantify spatial variability of fPAR and improve GPP estimates have not been established for mixed forests and heterogeneous landscapes in the Great Lakes Region, and are needed to estimate photosynthetic sinks for the Mid-Continent Regional Intensive Campaign. In this study, hemispheric photos were collected during the 2006 growing season to estimate fPAR, plant area index (PAI), leaf inclination angle, and clumping factors in >130 lowland and upland stands within the footprint of a 400 m eddy covariance flux tower near Park Falls, Wisconsin, USA. Airborne LiDAR and Quickbird imagery were acquired during leaf-on and leaf-off periods to make predictions of canopy structure, and resulting PAI/fPAR estimates were compared with litterfall measurements and products derived from the Moderate Resolution Spectroradiometer (MODIS). GPP was modeled with the MODIS MOD17A2 algorithm, using fine-resolution land cover and fPAR inputs that were spatially aggregated into units ranging from 30 m to 1 km square. Uncertainties and errors associated with fPAR methods and spatial resolutions are discussed based on agreement with flux tower observations.

  14. Interpretations of GLAS LiDAR for the Tapajos National Forest, Brazil

    Science.gov (United States)

    Hunter, M. O.; Keller, M.; Lefsky, M.; Espà­Rito-Santo, F.

    2007-12-01

    LiDAR remote sensing has proven to be a valuable source of information for characterization of forest structure. We conducted a study at the Tapajós National Forest (TNF) in the state of Pará, Brazil (centered at 3.56S 55.06W) to understand how forest structural properties interpreted from GLAS derived forest heights compared to a more traditional forest classification. The vegetation classification map was based on forest surveys, topography, soils, and interpretation of Landsat data. The original map groups TNF into 16 vegetation classifications. Using approximately 1500 GLAS waveform height predictions (Lefsky, ICESat Vegetation Product, heights ver.0.2) we calculated the 10th and 90th percentile values of distributions. These were interpreted as signals of disturbance and potential forest stand height respectively. We found no clear agreement on an area by area basis though general coherent patterns were observed. Areas close to human populations and those with high water-table depths showed a lower 10th percentile signal indicative of frequent recent disturbance. High plateau areas on clay soils had the greatest 90th percentile values. Our data suggests that statistical interpretation of GLAS may be valuable for comprehensive analyses of forest structure.

  15. A temperature inversion-induced air pollution process as analyzed from Mie LiDAR data.

    Science.gov (United States)

    Wu, Wanning; Zha, Yong; Zhang, Jiahua; Gao, Jay; He, Junliang

    2014-05-01

    A severe air pollution event in the Xianlin District of Nanjing City, China during 23-24 December 2012 was analyzed in terms of aerosol extinction coefficient and AOT retrieved from Mie scattering LiDAR data, in conjunction with in situ particulate concentrations measured near the Earth's surface, and the Weather Research Forecast-derived meteorological conditions. Comprehensive analyses of temperature, humidity, wind direction and velocity, and barometric pressure led to the conclusion that this pollution event was caused by advection inversion. In the absence of temperature inversion, the atmosphere at a height of 0.15 km has a relatively large extinction coefficient. In situ measured particulates exhibited a very large diurnal range. However, under the influence of turbulences, AOT was rather stable with a value <0.2 at an altitude below 0.8 km. Advection inversion appeared at 9:00 AM on 24 December, and did not dissipate until 22:00 PM. This temperature inversion, to some degree, inhibited the dispersion of near-surface particulates. Affected by this temperature inversion, the atmospheric extinction coefficient near the surface became noticeably larger. Near-surface particulates hardly varied at a concentration around 0.2mg/m(3). AOT at an altitude below 0.8 km rose to 0.31. PMID:24556291

  16. Estimates of Sediment Loading from Streambank Erosion Using Terrestrial LiDAR

    Science.gov (United States)

    Rizzo, D.; Hamshaw, S. D.; Anderson, H.; Underwood, K. L.; Dewoolkar, M. M.

    2013-12-01

    Channel and streambank erosion are common yet poorly quantified sources of sediment to streams and waterways worldwide. It is estimated that streambank erosion accounts for about one-third of the total sediment loading into Vermont lakes and waterways, contributing to water quality degradation, loss of agricultural lands, damaged infrastructure, sediment-bound nutrient loading and decreased habitat health. Therefore, an understanding of streambank stability and erosion is a prerequisite to developing accurate sediment budgets and reliably predicting geomorphic response of channels and resulting impacts on the health of streams and lakes. The motivation for this study came from rising concerns of eutrophication of Lake Champlain, Vermont. In the study presented here, periodic aerial photography and 3D scans of streambanks, using a handheld terrestrial LiDAR with sub-centimeter accuracy, were used to quantify erosion rates and sediment loadings at select streambank sites in the Mad River watershed (Winooski River basin) in Vermont over time periods that capture both single and multiple storm events. Estimates were compared to the predictions made using the USDA streambank stability model (BSTEM), parameterized via extensive fieldwork (i.e., borehole shear tests, jet erosion tests, and soil sampling and analysis for determining their index properties, soil matric suctions, and stream and bank water levels).

  17. New DArT markers for oat provide enhanced map coverage and global germplasm characterization

    Directory of Open Access Journals (Sweden)

    Ohm Herbert W

    2009-01-01

    Full Text Available Abstract Background Genomic discovery in oat and its application to oat improvement have been hindered by a lack of genetic markers common to different genetic maps, and by the difficulty of conducting whole-genome analysis using high-throughput markers. This study was intended to develop, characterize, and apply a large set of oat genetic markers based on Diversity Array Technology (DArT. Results Approximately 19,000 genomic clones were isolated from complexity-reduced genomic representations of pooled DNA samples from 60 oat varieties of global origin. These were screened on three discovery arrays, with more than 2000 polymorphic markers being identified for use in this study, and approximately 2700 potentially polymorphic markers being identified for use in future studies. DNA sequence was obtained for 2573 clones and assembled into a non-redundant set of 1770 contigs and singletons. Of these, 705 showed highly significant (Expectation vs. winter type, and to the presence of major breeding programs within geographical regions. Secondary clusters revealed groups that were often related to known pedigree structure. Conclusion These markers will provide a solid basis for future efforts in genomic discovery, comparative mapping, and the generation of an oat consensus map. They will also provide new opportunities for directed breeding of superior oat varieties, and guidance in the maintenance of oat genetic diversity.

  18. Mapping and monitoring coal mine subsidence using LiDAR and InSAR

    Energy Technology Data Exchange (ETDEWEB)

    Froese, C.R.; Mei, S. [Alberta Geological Survey, Edmonton, AB (Canada). Energy Resources Conservation Board

    2008-07-01

    In the early 1900s, the abandonment of coal mines in Alberta was not regulated and closure documentation was poor. Although the general locations of mines are known, the locations of the specific adits and shafts are not. As such, there are many cases in southwestern Alberta where infrastructure was built on top of old coal mine workings without any detailed records of the abandoned mine or displacement monitoring. The crowns of these workings have been subject to ongoing strain that is reflected at the surface. The rate at which the strain is progressing prior to collapse is not well understood. Mitigation of collapse events is site specific and reactive. This paper demonstrated that airborne LiDAR and spaceborne InSAR technologies can provide valuable information on the distribution of abandoned underground coal mine workings. Both remote sensing techniques were used on Turtle Mountain in the Crowsnest Pass to obtain quantitative information on landslide mechanics, including the patterns and rate of ground movement and subsidence. These techniques can be used to map the location of surface collapse and delineate the location of the coal mine workings that were not previously documented. It was concluded that these technologies will likely become more readily available in the future and incorporated into geo-engineering practices for use in ground hazard detection, monitoring and management. 8 refs., 6 figs.

  19. Hydrography change detection: the usefulness of surface channels derived From LiDAR DEMs for updating mapped hydrography

    Science.gov (United States)

    Poppenga, Sandra K.; Gesch, Dean B.; Worstell, Bruce B.

    2013-01-01

    The 1:24,000-scale high-resolution National Hydrography Dataset (NHD) mapped hydrography flow lines require regular updating because land surface conditions that affect surface channel drainage change over time. Historically, NHD flow lines were created by digitizing surface water information from aerial photography and paper maps. Using these same methods to update nationwide NHD flow lines is costly and inefficient; furthermore, these methods result in hydrography that lacks the horizontal and vertical accuracy needed for fully integrated datasets useful for mapping and scientific investigations. Effective methods for improving mapped hydrography employ change detection analysis of surface channels derived from light detection and ranging (LiDAR) digital elevation models (DEMs) and NHD flow lines. In this article, we describe the usefulness of surface channels derived from LiDAR DEMs for hydrography change detection to derive spatially accurate and time-relevant mapped hydrography. The methods employ analyses of horizontal and vertical differences between LiDAR-derived surface channels and NHD flow lines to define candidate locations of hydrography change. These methods alleviate the need to analyze and update the nationwide NHD for time relevant hydrography, and provide an avenue for updating the dataset where change has occurred.

  20. An Integrated Method for Mapping Impervious and Pervious Areas in Urban Environments Using Hyperspectral and LiDAR Data

    Science.gov (United States)

    Hashemi Beni, L.; McArdle, S.; Khayer, Y.

    2014-11-01

    As urbanization continues to increase and extreme climatic events become more prevalent, urban planners and engineers are actively implementing adaptive measures to protect urban assets and communities. To support the urban planning adaptation process, mapping of impervious and pervious areas is essential to understanding the hydrodynamic environment within urban areas for flood risk planning. The application of advance geospatial data and analytical techniques using remote sensing and GIS can improve land surface characterization to better quantify surface run-off and infiltration. This study presents a method to combine airborne hyperspectral and LiDAR data for classifying pervious (e.g. vegetation, gravel, and soil) and impervious (e.g. asphalt and concrete) areas within road allowance areas for the City of Surrey, British Columbia, Canada. Hyperspectral data was acquired using the Compact Airborne Spectrographic Imager (CASI) at 1 m ground spatial resolution, consisting of 72 spectral bands, and LiDAR data acquired from Leica Airborne LiDAR system at a density of 20 points/m2. A spectral library was established using 10 cm orthophotography and GIS data to identify surface features. In addition to spectral functions such as mean and standard deviation, several spectral indices were developed to discriminate between asphalt, concrete, gravel, vegetation, and shadows respectively. A spectral analysis of selected endmembers was conducted and an initial classification technique was applied using Spectral Angle Mapper (SAM). The classification results (i.e. shadows) were improved by integrating LIDAR data with the hyperspectral data.

  1. Mapping Above- and Below-Ground Biomass Components in Subtropical Forests Using Small-Footprint LiDAR

    Directory of Open Access Journals (Sweden)

    Lin Cao

    2014-06-01

    Full Text Available In order to better assess the spatial variability in subtropical forest biomass, the goal of our study was to use small-footprint, discrete-return Light Detection and Ranging (LiDAR data to accurately estimate and map above- and below-ground biomass components of subtropical forests. Foliage, branch, trunk, root, above-ground and total biomass of 53 plots (30 × 30 m were modeled using a range of LiDAR-derived metrics, with individual models built for each of the three dominant forest types using stepwise multi-regression analysis. A regular grid covered the entire study site with cell size 30 × 30 m corresponding to the same size of the plots; it was generated for mapping each biomass component. Overall, results indicate that biomass estimation was more accurate in coniferous forests, compared with the mixed and broadleaved plots. The coefficient of determination (R2 for individual models was significantly enhanced compared with an overall generic, or common, model. Using independent stand-level data from ground inventory, our results indicated that overall the model fit was significant for most of the biomass components, with relationships close to a 1:1 line, thereby indicating no significant bias. This research illustrates the potential for LiDAR as a technology to assess subtropical forest carbon accurately and to provide a better understanding of how forest ecosystems function in this region.

  2. Comparison of four methods of aerodynamic roughness length parameterization in semi-arid shrublands with airborne LiDAR, hyperspectral, and meteorological data

    Science.gov (United States)

    Li, A.; Mitchell, J. J.; Glenn, N. F.; Zhao, W.; Germino, M. J.; Allen, R.; Sankey, J. B.

    2013-12-01

    The aerodynamic roughness length (z0) plays an important role in the flux exchange between the land surface and atmosphere. Especially in semiarid shrublands, z0 is a key parameter for physical models of aeolian transport. z0 is influenced by the height, geometry, density and pattern of roughness elements. Light detection and ranging (LiDAR) is well suited to measure the vegetation height and has been used to estimate z0 across large areas. In this study, we combined airborne LiDAR, hyperspectral imagery and meteorological measurements to estimate z0, and assessed the ability of airborne LiDAR to estimate z0 over semi-arid shrublands. Airborne LiDAR data was used to derive the height of Wyoming big sagebrush (Artemisia tridentate subsp. wyomingensis) over a study area in the Great Basin, Idaho. Roughness density was related with percent vegetation cover which was estimated by integrating LiDAR and hyperspectral data, both collected in August 2011. Four methods of parameterization of z0 were applied and compared with the vegetation height from LiDAR; roughness from LiDAR and hyperspectral; NDVI and LAI from HyMap; and a geometric approach using meteorological data (e.g. wind speed). Micrometeorological measurements at two eddy covariance sites in the study area were used for validation of parameterized z0. The spatial variability of z0 was analyzed and the relationship with vegetation density was explored. The results demonstrated the potential of using airborne LiDAR data to estimate z0 at a regional scale in semi-arid shrublands. Furthermore, z0 showed a tight relationship with local variance of vegetation height and vegetation density.

  3. Diversity, genetic mapping, and signatures of domestication in the carrot (Daucus carota L.) genome, as revealed by Diversity Arrays Technology (DArT) markers

    OpenAIRE

    Grzebelus, Dariusz; Iorizzo, Massimo; Senalik, Douglas; Ellison, Shelby; Cavagnaro, Pablo; Macko-podgorni, Alicja; Heller-uszynska, Kasia; Kilian, Andrzej; Nothnagel, Thomas; Allender, Charlotte; Simon, Philipp W.; Baranski, Rafal

    2013-01-01

    Carrot is one of the most economically important vegetables worldwide, but genetic and genomic resources supporting carrot breeding remain limited. We developed a Diversity Arrays Technology (DArT) platform for wild and cultivated carrot and used it to investigate genetic diversity and to develop a saturated genetic linkage map of carrot. We analyzed a set of 900 DArT markers in a collection of plant materials comprising 94 cultivated and 65 wild carrot accessions. The accessions were attribu...

  4. Classification of Plot-Level Fire-Caused Tree Mortality in a Redwood Forest Using Digital Orthophotography and LiDAR

    OpenAIRE

    Bishop, Brian D.; Dietterick, Brian C.; White, Russell A.; Mastin, Tom B.

    2014-01-01

    Aerial and satellite imagery are widely used to assess the severity and impact of wildfires. Light detection and ranging (LiDAR) is a newer remote sensing technology that has demonstrated utility in measuring vegetation structure. Combined use of imagery and LiDAR may improve the assessment of wildfire impacts compared to imagery alone. Estimation of tree mortality at the plot scale could serve for more rapid, broad-scale, and lower cost post-fire assessments than feasible through field asses...

  5. Using Small-Footprint Discrete and Full-Waveform Airborne LiDAR Metrics to Estimate Total Biomass and Biomass Components in Subtropical Forests

    OpenAIRE

    Lin Cao; Coops, Nicholas C.; Txomin Hermosilla; John Innes; Jinsong Dai; Guanghui She

    2014-01-01

    An accurate estimation of total biomass and its components is critical for understanding the carbon cycle in forest ecosystems. The objectives of this study were to explore the performances of forest canopy structure characterization from a single small-footprint Light Detection and Ranging (LiDAR) dataset using two different techniques focusing on (i) 3-D canopy structural information by discrete (XYZ) LiDAR metrics (DR-metrics), and (ii) the detailed geometric and radiometric information...

  6. The impact of surface reflectance variability on total column differential absorption LiDAR measurements of atmospheric CO2

    OpenAIRE

    Monks, P. S.; Leigh, R. J.; Lawrence, J. P.

    2010-01-01

    The remote sensing technique, total column differential absorption LiDAR (TC-DIAL) has been proposed in a number of feasibility studies as a suitable method for making total column measurements of atmospheric CO2 from space. Among the sources of error associated with TC-DIAL retrievals from space is an undefined modulation of the received signals resulting from the variability in the Earth's surface reflectance between the LiDAR pulses. This source of uncertainty is investigated from a...

  7. Oral health behavior patterns among Tanzanian university students: a repeat cross-sectional survey

    Directory of Open Access Journals (Sweden)

    Åstrøm Anne

    2001-12-01

    Full Text Available Abstract Purpose This study examines oral health behavioral trends and the development of sociodemographic differences in oral health behaviors among Tanzanian students between 1999 and 2000. Methods The population targeted was students attending the Muhimbili University College of Health Sciences (MUCHS at the University of Dar es Salaam (UDSM, Dar es Salaam, Tanzania. Cross-sectional surveys were conducted and a total of 635 and 981 students, respectively, completed questionnaires in 1999 and 2001. Results Cross-tabulation analyses revealed that in 1999, the rates of abstinence from tobacco use, and of soft drink consumption, regular dental checkups, and intake of chocolate/candy were 84%, 51%, 48%, and 12%, respectively, among students of urban origin and 83%, 29%, 37%, and 5% among their rural counterparts. The corresponding rates in 2001 were 87%, 56%, 50%, and 9% among urban students and 84%, 44%, 38%, and 4% among rural ones. Multiple logistic regression analyses controlling for sex, age, place of origin, educational level, year of survey, and their interaction terms revealed a significant increase in the rate of soft drink consumption, implementation of oral hygiene measures, and abstinence from tobacco use between 1999 and 2001. Social inequalities observed in 1999, with urban students being more likely than their rural counterparts to take soft drinks and go for regular dental checkups, had leveled off by 2001. Conclusion This study provides initial evidence of oral health behavioral trends, that may be utilized in the planning of preventive programs among university students in Tanzania.

  8. Patterns, Characteristics, and Correlates of Adolescent Bully-Victims in Urban Tanzania

    Directory of Open Access Journals (Sweden)

    Benjamin A. Kamala

    2013-10-01

    Full Text Available Bullying is an understudied issue of public health importance in low-income countries. In the present study, we aimed to explore social and demographic factors associated with bullying among adolescents in a low-income country urban setting. We divided a sample of 2,154 school-attending adolescents into two groups, those who had been bullied during a 30-day period and those who were not. We considered age, sex, mental health, parent-relationship, hunger and social deprivation and truancy in our comparison of these two groups using logistic regression. Multinomial regression was also used to determine if there was a dose response relationship between bullying frequency and the aforementioned selected variables. We found that school-attending adolescents in Dar es Salaam were more likely to be truant, suffer from mental health problems and have experienced hunger. Adolescents who had parents which were more aware of their free time activities, were less likely to report being bullied. There were also significant differences in bullying frequency and certain variables, most notably with truancy, economic and social deprivation, and signs of depression. School settings in Dar es Salaam offer a potential for intervening in what are potentially harmful effects of bullying behavior among bully victims.

  9. IMMUNE REGULATING ES-PRODUCTS IN PARASITIC NEMATODES

    DEFF Research Database (Denmark)

    Bahlool, Qusay Zuhair Mohammad; Buchmann, Kurt

    Excretory/secretory (ES) products are molecules including various proteins produced by parasitic nematodes including larval A. simplex which is occurring in numerous marine fish hosts. The function of these substances and their effect on host physiology has not been fully described. The present work elucidates the effect of ES substances on the fish immune system by measuring immune gene expression in spleen and liver of rainbow trout (Oncorhynchus mykiss) injected intraperitoneally with ES products isolated from A. simplex third stage larvae. The overall gene expression profile of exposed fish showed a generalized down-regulation of the immune genes tested, suggesting a role of ES proteins in minimizing the immune reaction of rainbow trout against invading nematodes. We also tested the enzymatic activity of the ES proteins and found that lipase, esterase lipase, valine and cysteine arylamidases, naphthol-AS-BI-phosphohydrolase and a-galactosidase activities were present in the ES solution. This type of hydrolytic enzyme activity may play a role in nematode penetration of host tissue. Based on the notion that A. simplex ES-proteins may have an immune-depressive effect, it could also be suggested that worm enzymes directly target host immune effector molecules which would add to the decreased host immune responses and increased worm survival.

  10. Exact scattering solutions in an energy sudden (ES) representation

    International Nuclear Information System (INIS)

    In this paper, we lay down the theoretical foundations for computing exact scattering wave functions in a reference frame which moves in unison with the system internal coordinates. In this frame the (internal) coordinates appear to be fixed and its adoption leads very naturally (in zeroth order) to the energy sudden (ES) approximation [and the related infinite order sudden (IOS) method]. For this reason we call the new representation for describing the exact dynamics of a many channel scattering problem, the ES representation. Exact scattering solutions are derived in both time dependent and time independent frameworks for the representation and many interesting results in these frames are established. It is shown, e.g., that in a time dependent frame the usual