Land degradation and desertification are among the major environmental problems, resulting in red... more Land degradation and desertification are among the major environmental problems, resulting in reduced productivity and development of bare surfaces in arid and semi-arid areas of the world. One important factor that acts to increase soil stability and nutrient content, and thus to prevent water and wind erosion and enhance soil productivity of arid environment, is the presence of biological soil
Journal of Cardiovascular Pharmacology and Therapeutics, 2013
Contrast-induced nephropathy (CIN) is a significant cause of morbidity and mortality and effectiv... more Contrast-induced nephropathy (CIN) is a significant cause of morbidity and mortality and effective strategies for its prevention are greatly needed. The purpose of this retrospective, single-center study was to investigate whether nitrate use during percutaneous coronary artery intervention reduces the incidence of CIN. Chart review of all individuals who underwent percutaneous coronary intervention (PCI) from April 2010 to March 2011 was done. Included in the study were patients who were admitted to the hospital after percutaneous coronary artery intervention and had baseline and follow-up creatinine measured. Patients with end-stage renal disease requiring dialysis and those patients with insufficient information to calculate Mehran score were excluded. There were 199 patients who met the eligibility criteria for inclusion in this study. In the identified population, postprocedure renal function was compared between 112 patients who received nitrates prior to coronary intervention and 87 who did not. Baseline characteristics were similar between the 2 groups. Contrast-induced nephropathy was defined as either a 25% or a 0.5 mg/dL, or greater, increase in serum creatinine during the first 48 to 72 hours after contrast exposure. Overall, 43 (21.6%) patients developed CIN post-PCI. Of the patients who received nitrates, 15.2% developed renal impairment when compared to 29.9% in those who did not (odds ratio [OR] = 0.42, 95% confidence interval [CI] 0.21-0.84, P = .014). Multivariate logistic regression analysis demonstrated that nitrate use was independently correlated with a reduction in the development of contrast nephropathy (OR = 0.334, 95% CI 0.157-0.709, P = .004). Additionally, of the various methods of nitrate administration, intravenous infusion was shown to be the most efficacious route in preventing renal impairment (OR = 0.42, 95% CI 0.20-0.90, P = .03). In conclusion, the use of nitrates prior to PCI, particularly intravenous nitroglycerin infusion, may be associated with a decreased incidence of CIN.
The IEEE Conference on Local Computer Networks 30th Anniversary (LCN'05)l, 2005
Third generation (3G) technologies are becoming more widely deployed. However, a prerequisite for... more Third generation (3G) technologies are becoming more widely deployed. However, a prerequisite for the successful deployment of such services is the measurement of practical performance characteristics offered by the underlying wireless network (eg 3G). This paper presents ...
Journal of Cardiovascular Pharmacology and Therapeutics, 2013
Contrast-induced nephropathy (CIN) is a significant cause of morbidity and mortality and effectiv... more Contrast-induced nephropathy (CIN) is a significant cause of morbidity and mortality and effective strategies for its prevention are greatly needed. The purpose of this retrospective, single-center study was to investigate whether nitrate use during percutaneous coronary artery intervention reduces the incidence of CIN. Chart review of all individuals who underwent percutaneous coronary intervention (PCI) from April 2010 to March 2011 was done. Included in the study were patients who were admitted to the hospital after percutaneous coronary artery intervention and had baseline and follow-up creatinine measured. Patients with end-stage renal disease requiring dialysis and those patients with insufficient information to calculate Mehran score were excluded. There were 199 patients who met the eligibility criteria for inclusion in this study. In the identified population, postprocedure renal function was compared between 112 patients who received nitrates prior to coronary intervention and 87 who did not. Baseline characteristics were similar between the 2 groups. Contrast-induced nephropathy was defined as either a 25% or a 0.5 mg/dL, or greater, increase in serum creatinine during the first 48 to 72 hours after contrast exposure. Overall, 43 (21.6%) patients developed CIN post-PCI. Of the patients who received nitrates, 15.2% developed renal impairment when compared to 29.9% in those who did not (odds ratio [OR] = 0.42, 95% confidence interval [CI] 0.21-0.84, P = .014). Multivariate logistic regression analysis demonstrated that nitrate use was independently correlated with a reduction in the development of contrast nephropathy (OR = 0.334, 95% CI 0.157-0.709, P = .004). Additionally, of the various methods of nitrate administration, intravenous infusion was shown to be the most efficacious route in preventing renal impairment (OR = 0.42, 95% CI 0.20-0.90, P = .03). In conclusion, the use of nitrates prior to PCI, particularly intravenous nitroglycerin infusion, may be associated with a decreased incidence of CIN.
ABSTRACT Most areas where biological soil crusts (BSC) develop undergo a climate with heavy but s... more ABSTRACT Most areas where biological soil crusts (BSC) develop undergo a climate with heavy but sparse rainfall events. The hydrological response of the BSC, namely the amount of runoff, is highly variable. Rainfall simulation experiments were conducted in Sadoré, south-western Niger. The aim was to estimate the influence of the BSC coverage on the quantity and quality of water, particles and solutes exported during simulated rainfall events. Ten 1 m2 plots were selected based on their various degree of BSC cover (4-89%) and type of underlying physical crust (structural or erosion crusts). The plots are located on similar sandy soil with moderate slope (3-6%). The experiments consisted of two rainfall events, spaced at 22-hours interval: 60 mm/h for 20 min, and 120 mm/h for 10 min. During each experiments particles dectached and runoff water were collected and filtered in the laboratory. C and N content were determined both in water and sediments samples.. These analyses were completed by measurements of phospholipid fatty acids and chlorophyll a contents in sediments and BSC samples collected before and after the rainfall. Mineral N and microbial biomass carbon of BSC samples were also analysed. The results confirmed that BSC reduce the loss of particles and exert a protective effect on soils with regard to particle detachment by raindrop. However there is no general relationship between the BSC coverage and the loss of C and N due to runoff. Contrarily, the C and N content in the sediments is negatively correlated to their mass. The type of physical crust on which the BSC develop also has to be taken into account. These results will contribute to the region-wide modeling of the role of BSC in biogeochemical cycles.
ABSTRACT In Sahelian region, concentrated overland flow often leads to the formation of gullies. ... more ABSTRACT In Sahelian region, concentrated overland flow often leads to the formation of gullies. Although this phenomenon is widespread in those regions, research efforts are still needed to be able to model their spatial distribution and the role of the different parameters involved in this process. In this context, the objectives of this study are twofold. The first step is to investigate to what extent the role of Sahelian soil surface crusts (biological and/or physical) on soil surface infiltrability and detachment affect the formation and development of gullies. The second step is to integrate the results of these investigations in a simple geomorphological model to predict gully location at the watershed scale. The evaluation of the resulting model on two test catchments demonstrated that the integration of soil crusting is a key parameter to insure the quality and relevance of gully prediction. The model is able to distinguish between two types of gullies, those whose width range between 0.5m and 4m and those whose width exceeds 4m. The application of the model at the regional scale is however limited by the resolution of available regional digital elevation model (i.e. the 90m resolution SRTM DEM) which only permits the prediction of large gullies (width > 4m).
ABSTRACT Land degradation and desertification are among the major environmental problems, resulti... more ABSTRACT Land degradation and desertification are among the major environmental problems, resulting in reduced productivity and development of bare surfaces in arid and semi-arid areas of the world. One important factor that acts to increase soil stability and nutrient content, and thus to prevent water and wind erosion and enhance soil productivity of arid environment, is the presence of biological soil crusts (BSCs). They are the dominant ground cover and a key component of arid environments built up mainly by cyanobacteria. They enhance degraded soil quality by providing a stable and water-retaining substratum and increasing fertility by N and C fixations. The BioCrust project, funded by ANR (VMCS 2008), focuses on BSCs in the Sahelian zone of West Africa (Niger), a highly vulnerable zone facing soil degradation due to the harsh climatic conditions, with variable rainfall, and high anthropic pressure on land use. Unlike arid areas of developed countries (USA, Australia and Israel) or China where BSCs have been extensively studied, studies from Sahelian zone (Africa) are limited (neither the inventory of their different form nor the estimation of their spatial extension has been carried out). The form, structure and composition of BSCs vary depending on characteristics related to soils and biological composition. This study focuses on the soils characterisation using ground-based spectroradiometry. An extensive database was built included spectral measurements on BSCs, bare soils and vegetation that occur in the same area, visual criteria, in situ and laboratory measurements on the physical, chemical and biological characteristics of BSCs and their substratum. The work is carried out on geo-statistical processing of data acquired in sites along a north-south climatic gradient and three types of representative land uses. The investigated areas are highly vulnerable zone facing soil degradation due to the harsh climatic conditions, with variable rainfall, and high anthropic pressure on land use Soil surface disturbances due to the intensification of human activities. Spectral field and laboratory data were acquired in 2009, 2010 and 2011 with the FieldSpec Pro®. The spectra of soils with respect to different parameters are studied in details and their separability from BSCs, vegetation and vegetation residue as well are be analysed. First, the effect of the mineralogy and the geochemical variables on the soil reflectance properties is studied and then the feasibility to resolve some of these effects with satellite imagery (e. g., ASTER) will be tested in order to define the potential capability for identifying the locations of sensitive areas affected by soil degradation and appearance of BSCs.
ABSTRACT Biological soil crusts occur extensively in semi-arid regions; in western Niger, they ar... more ABSTRACT Biological soil crusts occur extensively in semi-arid regions; in western Niger, they are associated with various types of physical soil crusts. The objective of this study is to elaborate and calibrate a dynamic erosion model coupling the Shallow Water equations with the Hairsine-Rose model for different sediment size classes. The study is based on runoff measurements performed in situ on ten 1-m2 plots under simulated rainfalls. Biological soil crusts capped pre-existing physical soil crusts with a percentage cover between 39 and 80% on structural crusts compared to 4 and 29% on erosion crusts. Calibration is firstly performed on the saturated infiltration capacity of the different crust types using a minimising algorithm where the distance is based on the Nash-Sutcliffe coefficient. The result is that whatever the suction values we find a power relation between the infiltration of BSC and the infiltration of BSC overlying physical soil crusts. The erosion model is also calibrated to take the different types of crust into account. These results will contribute to evaluate the potential role of biological soil crusts in soil and water redistribution modelling in arid environment of western Niger.
Quality-of-Experience (QoE) is a human centric notion that produces the blue print of human perce... more Quality-of-Experience (QoE) is a human centric notion that produces the blue print of human perception, feelings, needs and intentions while Quality-of-Service (QoS) is a technology centric metric used to assess the performance of a multimedia application and/or network. To ensure superior video QoE, it is important to understand the relationship between QoE and QoS. To achieve this goal, we conducted a pilot subjective user study simulating a video streaming service over a broadband network with varying distortion scenarios, namely packet losses (0, 0.5, 1, 3,7, and 15%), packet reorder (0, 1, 5, 10, 20, and 30%), and coding bit rates (100, 400, 600, and 800 Kbps). Users were asked to rate their experience using a subjective quantitative metric (termed Perceived Video Quality, PVQ) and qualitative indicators of “experience.” Simulation results suggest a) an exponential relationship between PVQ and packet loss and between PVQ and packet reorder, and b) a logarithmic relationship between PVQ and video bit rate. Similar trends were observed with the qualitative indicators. Exploratory analysis with two objective video quality metrics suggests that trends similar to those obtained with the subjective ratings were obtained, particularly with a full-reference metric.
ABSTRACT This study was conducted in Champagne vineyards in France, and the objectives were to co... more ABSTRACT This study was conducted in Champagne vineyards in France, and the objectives were to compare the main cultivation practices in Champagne vineyards and to specify the conditions required for the optimum effect of inter-row grass cover on runoff and erosion in experimental plots of 0.25 m² under simulated rainfall. Three types of ground cover were studied. In the bark-and-vine-prunings plots, the runoff coefficient (RC) ranged from 1.3 to 4.0% and soil losses were <1 g/m2/h. In the bare soil (BS) plot, the highest RC of the study was found (80.0%) and soil losses reached 7.4 g/m2/h. In the grass cover plots, the RC and amount of eroded soil were highly variable: the RCs ranged from 0.4 to 77.0%, and soil losses were between less than 1 and 13.4 g/m2/h. Soil type, soil moisture, slope and agricultural practices did not account for the variability. In fact, the density of grass cover in the wheel tracks explained a portion of this variability. The lack of grass in the centre of the inter-row allowed for a preferential flow and created an erosion line in the wheel tracks where the soil was compacted. This study showed that grass cover in a vineyard was not necessarily sufficient to reduce surface runoff and prevent soil erosion. To be effective, the grass cover must be dense enough in the wheel tracks of agricultural machinery to avoid RCs close to the RC achieved with BS.
2010 IEEE International Symposium on Broadband Multimedia Systems and Broadcasting (BMSB), 2010
Abstract-The delivery of High Definition Television (HDTV) over IP networks, namely the HD IPTV, ... more Abstract-The delivery of High Definition Television (HDTV) over IP networks, namely the HD IPTV, has emerged as one of the major distribution and access techniques for broadband multimedia services. IPTV adopts H.264/AVC as its coding standard due to its high video ...
2009 IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, 2009
Abstract High Definition (HD) content delivery over IP networks has become a reality in the mark... more Abstract High Definition (HD) content delivery over IP networks has become a reality in the market of entertainment technologies. This paper presents a professional testbed deployed to emulate a real use case of delivering high definition TV material over an IPTV network. ...
2012 IEEE Consumer Communications and Networking Conference (CCNC), 2012
High Definition (HD) content delivery over IP networks is now a reality in the entertainment mark... more High Definition (HD) content delivery over IP networks is now a reality in the entertainment marketplace. Such networks can suffer packet loss, especially on the last mile link. This results in time-variant video quality. In this paper we first present an analysis of the human perception of network impairment on HD IPTV quality. Second, we propose a method, based on
IEEE international Symposium on Broadband Multimedia Systems and Broadcasting, 2012
ABSTRACT TV delivery over IP networks (i.e. IPTV) has emerged as one of the major distribution an... more ABSTRACT TV delivery over IP networks (i.e. IPTV) has emerged as one of the major distribution and access techniques for broadband multimedia services. IPTV adopts H.264 as its coding standard due to its high video compression efficiency as well as powerful error resilience features. This paper presents studies on some of the H.264/AVC error resilience features applied to IPTV applications, namely, high definition (i.e., HD IPTV) and wireless/handheld extension. Test systems are deployed to simulate: (1) The delivery of lower resolution TV programs over wireless channels; (2) The delivery of HD video over an xDSL based IPTV network. Flexible Macroblock Ordering (FMO) slice grouping is assessed in handheld IPTV applications. Optimal slice size is obtained for HD video transmission over impaired channels. The quality of experience related to the Instantaneous Decoding Refreshing (IDR) interval is characterized for HD IPTV.
2009 11th IEEE International Symposium on Multimedia, 2009
AbstractIn the last few years, Internet Protocol Television (IPTV) has emerged as one of the maj... more AbstractIn the last few years, Internet Protocol Television (IPTV) has emerged as one of the major distribution technologies for broadband multimedia services. However, the delivery of High Definition Television (HDTV) services over IP networks still faces many challenges. ...
Cellular networks offer mobility to users; however performance is often subject to bandwidth fluc... more Cellular networks offer mobility to users; however performance is often subject to bandwidth fluctuation. This phenomenon becomes more critical in the case of applications based on video analysis, such as remote diagnostic in ambulances or remote security control. A number ...
Omneya Issa 1, Jean-Charles Gregoire , Yacine Belala 1 and James Wong 1 International Institute o... more Omneya Issa 1, Jean-Charles Gregoire , Yacine Belala 1 and James Wong 1 International Institute of Telecommunications (IIT) {omneya.issa, yacine.belala, james.wong} @iitelecom.com 2 INRS-EMT, University of Quebec { gregoire@emt.inrs.ca} Montreal, Quebec, Canada
Many soils in South Africa have low nutrient supply, poor structural stability and are prone to s... more Many soils in South Africa have low nutrient supply, poor structural stability and are prone to soil erosion due to susceptibility to surface sealing and crusting. Two crusting soils from the Eastern Cape Province, South Africa were used to evaluate the effects of inoculation with a strain of Nostoc on soil structure, fertility and maize growth. The Nostoc suspension was
Land degradation and desertification are among the major environmental problems, resulting in red... more Land degradation and desertification are among the major environmental problems, resulting in reduced productivity and development of bare surfaces in arid and semi-arid areas of the world. One important factor that acts to increase soil stability and nutrient content, and thus to prevent water and wind erosion and enhance soil productivity of arid environment, is the presence of biological soil
Journal of Cardiovascular Pharmacology and Therapeutics, 2013
Contrast-induced nephropathy (CIN) is a significant cause of morbidity and mortality and effectiv... more Contrast-induced nephropathy (CIN) is a significant cause of morbidity and mortality and effective strategies for its prevention are greatly needed. The purpose of this retrospective, single-center study was to investigate whether nitrate use during percutaneous coronary artery intervention reduces the incidence of CIN. Chart review of all individuals who underwent percutaneous coronary intervention (PCI) from April 2010 to March 2011 was done. Included in the study were patients who were admitted to the hospital after percutaneous coronary artery intervention and had baseline and follow-up creatinine measured. Patients with end-stage renal disease requiring dialysis and those patients with insufficient information to calculate Mehran score were excluded. There were 199 patients who met the eligibility criteria for inclusion in this study. In the identified population, postprocedure renal function was compared between 112 patients who received nitrates prior to coronary intervention and 87 who did not. Baseline characteristics were similar between the 2 groups. Contrast-induced nephropathy was defined as either a 25% or a 0.5 mg/dL, or greater, increase in serum creatinine during the first 48 to 72 hours after contrast exposure. Overall, 43 (21.6%) patients developed CIN post-PCI. Of the patients who received nitrates, 15.2% developed renal impairment when compared to 29.9% in those who did not (odds ratio [OR] = 0.42, 95% confidence interval [CI] 0.21-0.84, P = .014). Multivariate logistic regression analysis demonstrated that nitrate use was independently correlated with a reduction in the development of contrast nephropathy (OR = 0.334, 95% CI 0.157-0.709, P = .004). Additionally, of the various methods of nitrate administration, intravenous infusion was shown to be the most efficacious route in preventing renal impairment (OR = 0.42, 95% CI 0.20-0.90, P = .03). In conclusion, the use of nitrates prior to PCI, particularly intravenous nitroglycerin infusion, may be associated with a decreased incidence of CIN.
The IEEE Conference on Local Computer Networks 30th Anniversary (LCN'05)l, 2005
Third generation (3G) technologies are becoming more widely deployed. However, a prerequisite for... more Third generation (3G) technologies are becoming more widely deployed. However, a prerequisite for the successful deployment of such services is the measurement of practical performance characteristics offered by the underlying wireless network (eg 3G). This paper presents ...
Journal of Cardiovascular Pharmacology and Therapeutics, 2013
Contrast-induced nephropathy (CIN) is a significant cause of morbidity and mortality and effectiv... more Contrast-induced nephropathy (CIN) is a significant cause of morbidity and mortality and effective strategies for its prevention are greatly needed. The purpose of this retrospective, single-center study was to investigate whether nitrate use during percutaneous coronary artery intervention reduces the incidence of CIN. Chart review of all individuals who underwent percutaneous coronary intervention (PCI) from April 2010 to March 2011 was done. Included in the study were patients who were admitted to the hospital after percutaneous coronary artery intervention and had baseline and follow-up creatinine measured. Patients with end-stage renal disease requiring dialysis and those patients with insufficient information to calculate Mehran score were excluded. There were 199 patients who met the eligibility criteria for inclusion in this study. In the identified population, postprocedure renal function was compared between 112 patients who received nitrates prior to coronary intervention and 87 who did not. Baseline characteristics were similar between the 2 groups. Contrast-induced nephropathy was defined as either a 25% or a 0.5 mg/dL, or greater, increase in serum creatinine during the first 48 to 72 hours after contrast exposure. Overall, 43 (21.6%) patients developed CIN post-PCI. Of the patients who received nitrates, 15.2% developed renal impairment when compared to 29.9% in those who did not (odds ratio [OR] = 0.42, 95% confidence interval [CI] 0.21-0.84, P = .014). Multivariate logistic regression analysis demonstrated that nitrate use was independently correlated with a reduction in the development of contrast nephropathy (OR = 0.334, 95% CI 0.157-0.709, P = .004). Additionally, of the various methods of nitrate administration, intravenous infusion was shown to be the most efficacious route in preventing renal impairment (OR = 0.42, 95% CI 0.20-0.90, P = .03). In conclusion, the use of nitrates prior to PCI, particularly intravenous nitroglycerin infusion, may be associated with a decreased incidence of CIN.
ABSTRACT Most areas where biological soil crusts (BSC) develop undergo a climate with heavy but s... more ABSTRACT Most areas where biological soil crusts (BSC) develop undergo a climate with heavy but sparse rainfall events. The hydrological response of the BSC, namely the amount of runoff, is highly variable. Rainfall simulation experiments were conducted in Sadoré, south-western Niger. The aim was to estimate the influence of the BSC coverage on the quantity and quality of water, particles and solutes exported during simulated rainfall events. Ten 1 m2 plots were selected based on their various degree of BSC cover (4-89%) and type of underlying physical crust (structural or erosion crusts). The plots are located on similar sandy soil with moderate slope (3-6%). The experiments consisted of two rainfall events, spaced at 22-hours interval: 60 mm/h for 20 min, and 120 mm/h for 10 min. During each experiments particles dectached and runoff water were collected and filtered in the laboratory. C and N content were determined both in water and sediments samples.. These analyses were completed by measurements of phospholipid fatty acids and chlorophyll a contents in sediments and BSC samples collected before and after the rainfall. Mineral N and microbial biomass carbon of BSC samples were also analysed. The results confirmed that BSC reduce the loss of particles and exert a protective effect on soils with regard to particle detachment by raindrop. However there is no general relationship between the BSC coverage and the loss of C and N due to runoff. Contrarily, the C and N content in the sediments is negatively correlated to their mass. The type of physical crust on which the BSC develop also has to be taken into account. These results will contribute to the region-wide modeling of the role of BSC in biogeochemical cycles.
ABSTRACT In Sahelian region, concentrated overland flow often leads to the formation of gullies. ... more ABSTRACT In Sahelian region, concentrated overland flow often leads to the formation of gullies. Although this phenomenon is widespread in those regions, research efforts are still needed to be able to model their spatial distribution and the role of the different parameters involved in this process. In this context, the objectives of this study are twofold. The first step is to investigate to what extent the role of Sahelian soil surface crusts (biological and/or physical) on soil surface infiltrability and detachment affect the formation and development of gullies. The second step is to integrate the results of these investigations in a simple geomorphological model to predict gully location at the watershed scale. The evaluation of the resulting model on two test catchments demonstrated that the integration of soil crusting is a key parameter to insure the quality and relevance of gully prediction. The model is able to distinguish between two types of gullies, those whose width range between 0.5m and 4m and those whose width exceeds 4m. The application of the model at the regional scale is however limited by the resolution of available regional digital elevation model (i.e. the 90m resolution SRTM DEM) which only permits the prediction of large gullies (width > 4m).
ABSTRACT Land degradation and desertification are among the major environmental problems, resulti... more ABSTRACT Land degradation and desertification are among the major environmental problems, resulting in reduced productivity and development of bare surfaces in arid and semi-arid areas of the world. One important factor that acts to increase soil stability and nutrient content, and thus to prevent water and wind erosion and enhance soil productivity of arid environment, is the presence of biological soil crusts (BSCs). They are the dominant ground cover and a key component of arid environments built up mainly by cyanobacteria. They enhance degraded soil quality by providing a stable and water-retaining substratum and increasing fertility by N and C fixations. The BioCrust project, funded by ANR (VMCS 2008), focuses on BSCs in the Sahelian zone of West Africa (Niger), a highly vulnerable zone facing soil degradation due to the harsh climatic conditions, with variable rainfall, and high anthropic pressure on land use. Unlike arid areas of developed countries (USA, Australia and Israel) or China where BSCs have been extensively studied, studies from Sahelian zone (Africa) are limited (neither the inventory of their different form nor the estimation of their spatial extension has been carried out). The form, structure and composition of BSCs vary depending on characteristics related to soils and biological composition. This study focuses on the soils characterisation using ground-based spectroradiometry. An extensive database was built included spectral measurements on BSCs, bare soils and vegetation that occur in the same area, visual criteria, in situ and laboratory measurements on the physical, chemical and biological characteristics of BSCs and their substratum. The work is carried out on geo-statistical processing of data acquired in sites along a north-south climatic gradient and three types of representative land uses. The investigated areas are highly vulnerable zone facing soil degradation due to the harsh climatic conditions, with variable rainfall, and high anthropic pressure on land use Soil surface disturbances due to the intensification of human activities. Spectral field and laboratory data were acquired in 2009, 2010 and 2011 with the FieldSpec Pro®. The spectra of soils with respect to different parameters are studied in details and their separability from BSCs, vegetation and vegetation residue as well are be analysed. First, the effect of the mineralogy and the geochemical variables on the soil reflectance properties is studied and then the feasibility to resolve some of these effects with satellite imagery (e. g., ASTER) will be tested in order to define the potential capability for identifying the locations of sensitive areas affected by soil degradation and appearance of BSCs.
ABSTRACT Biological soil crusts occur extensively in semi-arid regions; in western Niger, they ar... more ABSTRACT Biological soil crusts occur extensively in semi-arid regions; in western Niger, they are associated with various types of physical soil crusts. The objective of this study is to elaborate and calibrate a dynamic erosion model coupling the Shallow Water equations with the Hairsine-Rose model for different sediment size classes. The study is based on runoff measurements performed in situ on ten 1-m2 plots under simulated rainfalls. Biological soil crusts capped pre-existing physical soil crusts with a percentage cover between 39 and 80% on structural crusts compared to 4 and 29% on erosion crusts. Calibration is firstly performed on the saturated infiltration capacity of the different crust types using a minimising algorithm where the distance is based on the Nash-Sutcliffe coefficient. The result is that whatever the suction values we find a power relation between the infiltration of BSC and the infiltration of BSC overlying physical soil crusts. The erosion model is also calibrated to take the different types of crust into account. These results will contribute to evaluate the potential role of biological soil crusts in soil and water redistribution modelling in arid environment of western Niger.
Quality-of-Experience (QoE) is a human centric notion that produces the blue print of human perce... more Quality-of-Experience (QoE) is a human centric notion that produces the blue print of human perception, feelings, needs and intentions while Quality-of-Service (QoS) is a technology centric metric used to assess the performance of a multimedia application and/or network. To ensure superior video QoE, it is important to understand the relationship between QoE and QoS. To achieve this goal, we conducted a pilot subjective user study simulating a video streaming service over a broadband network with varying distortion scenarios, namely packet losses (0, 0.5, 1, 3,7, and 15%), packet reorder (0, 1, 5, 10, 20, and 30%), and coding bit rates (100, 400, 600, and 800 Kbps). Users were asked to rate their experience using a subjective quantitative metric (termed Perceived Video Quality, PVQ) and qualitative indicators of “experience.” Simulation results suggest a) an exponential relationship between PVQ and packet loss and between PVQ and packet reorder, and b) a logarithmic relationship between PVQ and video bit rate. Similar trends were observed with the qualitative indicators. Exploratory analysis with two objective video quality metrics suggests that trends similar to those obtained with the subjective ratings were obtained, particularly with a full-reference metric.
ABSTRACT This study was conducted in Champagne vineyards in France, and the objectives were to co... more ABSTRACT This study was conducted in Champagne vineyards in France, and the objectives were to compare the main cultivation practices in Champagne vineyards and to specify the conditions required for the optimum effect of inter-row grass cover on runoff and erosion in experimental plots of 0.25 m² under simulated rainfall. Three types of ground cover were studied. In the bark-and-vine-prunings plots, the runoff coefficient (RC) ranged from 1.3 to 4.0% and soil losses were <1 g/m2/h. In the bare soil (BS) plot, the highest RC of the study was found (80.0%) and soil losses reached 7.4 g/m2/h. In the grass cover plots, the RC and amount of eroded soil were highly variable: the RCs ranged from 0.4 to 77.0%, and soil losses were between less than 1 and 13.4 g/m2/h. Soil type, soil moisture, slope and agricultural practices did not account for the variability. In fact, the density of grass cover in the wheel tracks explained a portion of this variability. The lack of grass in the centre of the inter-row allowed for a preferential flow and created an erosion line in the wheel tracks where the soil was compacted. This study showed that grass cover in a vineyard was not necessarily sufficient to reduce surface runoff and prevent soil erosion. To be effective, the grass cover must be dense enough in the wheel tracks of agricultural machinery to avoid RCs close to the RC achieved with BS.
2010 IEEE International Symposium on Broadband Multimedia Systems and Broadcasting (BMSB), 2010
Abstract-The delivery of High Definition Television (HDTV) over IP networks, namely the HD IPTV, ... more Abstract-The delivery of High Definition Television (HDTV) over IP networks, namely the HD IPTV, has emerged as one of the major distribution and access techniques for broadband multimedia services. IPTV adopts H.264/AVC as its coding standard due to its high video ...
2009 IEEE International Symposium on Broadband Multimedia Systems and Broadcasting, 2009
Abstract High Definition (HD) content delivery over IP networks has become a reality in the mark... more Abstract High Definition (HD) content delivery over IP networks has become a reality in the market of entertainment technologies. This paper presents a professional testbed deployed to emulate a real use case of delivering high definition TV material over an IPTV network. ...
2012 IEEE Consumer Communications and Networking Conference (CCNC), 2012
High Definition (HD) content delivery over IP networks is now a reality in the entertainment mark... more High Definition (HD) content delivery over IP networks is now a reality in the entertainment marketplace. Such networks can suffer packet loss, especially on the last mile link. This results in time-variant video quality. In this paper we first present an analysis of the human perception of network impairment on HD IPTV quality. Second, we propose a method, based on
IEEE international Symposium on Broadband Multimedia Systems and Broadcasting, 2012
ABSTRACT TV delivery over IP networks (i.e. IPTV) has emerged as one of the major distribution an... more ABSTRACT TV delivery over IP networks (i.e. IPTV) has emerged as one of the major distribution and access techniques for broadband multimedia services. IPTV adopts H.264 as its coding standard due to its high video compression efficiency as well as powerful error resilience features. This paper presents studies on some of the H.264/AVC error resilience features applied to IPTV applications, namely, high definition (i.e., HD IPTV) and wireless/handheld extension. Test systems are deployed to simulate: (1) The delivery of lower resolution TV programs over wireless channels; (2) The delivery of HD video over an xDSL based IPTV network. Flexible Macroblock Ordering (FMO) slice grouping is assessed in handheld IPTV applications. Optimal slice size is obtained for HD video transmission over impaired channels. The quality of experience related to the Instantaneous Decoding Refreshing (IDR) interval is characterized for HD IPTV.
2009 11th IEEE International Symposium on Multimedia, 2009
AbstractIn the last few years, Internet Protocol Television (IPTV) has emerged as one of the maj... more AbstractIn the last few years, Internet Protocol Television (IPTV) has emerged as one of the major distribution technologies for broadband multimedia services. However, the delivery of High Definition Television (HDTV) services over IP networks still faces many challenges. ...
Cellular networks offer mobility to users; however performance is often subject to bandwidth fluc... more Cellular networks offer mobility to users; however performance is often subject to bandwidth fluctuation. This phenomenon becomes more critical in the case of applications based on video analysis, such as remote diagnostic in ambulances or remote security control. A number ...
Omneya Issa 1, Jean-Charles Gregoire , Yacine Belala 1 and James Wong 1 International Institute o... more Omneya Issa 1, Jean-Charles Gregoire , Yacine Belala 1 and James Wong 1 International Institute of Telecommunications (IIT) {omneya.issa, yacine.belala, james.wong} @iitelecom.com 2 INRS-EMT, University of Quebec { gregoire@emt.inrs.ca} Montreal, Quebec, Canada
Many soils in South Africa have low nutrient supply, poor structural stability and are prone to s... more Many soils in South Africa have low nutrient supply, poor structural stability and are prone to soil erosion due to susceptibility to surface sealing and crusting. Two crusting soils from the Eastern Cape Province, South Africa were used to evaluate the effects of inoculation with a strain of Nostoc on soil structure, fertility and maize growth. The Nostoc suspension was
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