Danladi Yusuf Gumel | UPM - Universiti Putra Malaysia (original) (raw)

Papers by Danladi Yusuf Gumel

The transportation sector has greatly contributed to the socio-economic development with inherent... more The transportation sector has greatly contributed to the socio-economic development with inherent environmental impacts. This study estimated the emission of CO2 from transportation sector, particularly from the use of passenger cars in Selangor Malaysia. The total CO2 emission from the region was calculated based on total fuel consumption (Kg) and Emission Factor of CO2 (gr/kg fuel). Lorries and cars were responsible for the highest CO2 emission and the emissions rate were directly related to the type and amount of fuel used and emission factor of fuel. High amount of CO2 emission was due to increase in vehicles on the road thereby increasing pollution on the environment. GIS is one of the most suitable methods to estimate the total CO2 emission and the split between different vehicle types as it determined by the kilometre covered for each vehicle category

Sensitivity of paddy rice to climatic perturbation makes paddy farmers to be vulnerable to climat... more Sensitivity of paddy rice to climatic perturbation makes paddy farmers to be vulnerable to climate change and variability, this resulted to the decline in paddy productivity and reduction in farmers' income, thereby exacerbating the socioeconomic wellbeing and poverty level of the farmers in Malaysia. Tackling vulnerability to climate change through effective policy action requires understanding of farmers' adaptive capacity. This study analysed adaptive capacity of the paddy farmers and factors that causes differences in the farmers' adaptive capacity in the study areas. Paddy farmers' adaptive capacity levels were determined using a composite index score by linearly aggregating the farmers' five capital indicators (human, physical, financial, social, and management capitals). The study showed that adaptive capacity index scores of the entire respondents' ranges from-0.289 to 0.392 with Mean of-0.003 and standard deviation 0.174. About 200 (44.4%) of the respondent have low adaptive capacity, 144 (32.0%) have moderate adaptive capacity, while 106 (23.6%) have high adaptive capacity. Moreover, adaptive capacity as a component of vulnerability has immediate policy implications, in that its improvement reduces the sensitivity levels of the paddy farmers to climate change variability. As such, it is important to evolve national climate change adaptation policy that will guide policy makers to address region specific needs of the paddy farmers. The policy options should involve educating young workforce to embrace paddy farming. More extension services to enhance the skill of the oldaged farmers. Provide access to more financial capital for investment in education etc.

IOP Conference Series: Earth and Environmental Science, 2014

In this study, Aerosol Optical Depth (AOD) at 550nm from the MODIS sensor on board the Terra/Aqua... more In this study, Aerosol Optical Depth (AOD) at 550nm from the MODIS sensor on board the Terra/Aqua satellites were compared with sun photometer (CE-318) measurements from 11 AERONET stations in China. The average correlation coefficient (R) value from the AOD product, using the Aqua-MODIS Deep Blue algorithm, in the Hexi Corridor was 0.67. The MODIS Dark Target algorithm AOD product is superior to Deep Blue algorithm AOD products in SACOL of the Semi-arid regions of the Loess Plateau. These two kinds of algorithm are not applicable to sites in Lanzhou city. The average R value of Dark Target algorithm AOD MODIS products is 0.91 for Terra and 0.88 for Aqua in the eastern part of China. According to the analysis of spatial and temporal characteristics of the two MODIS AOD products in China, high value areas are mainly distributed in the southern part of Xinjiang (0.5~0.8), Sichuan Basin (0.8~0.9), North China (0.6~0.8) and the middle and lower reaches of the Changjiang River (0.8~1.0). The Deep Blue algorithm for Aqua-MODIS is a good supplement for the retrieval of AOD above bright surfaces of deserts in Northwest China.

Malaysian Journal of Analytical Science, 2016

The urbanization in Klang Valley, Peninsular Malaysia over the last decades has induce the atmosp... more The urbanization in Klang Valley, Peninsular Malaysia over the last decades has induce the atmospheric pollution’s risk resulted to negative impact on the environment. The aims of this paper are to identify the spatial-temporal relationship of particulate matter (PM10), to determine the characteristic of each location and to classify hierarchical of the location in relation to their impact on PM10 concentration in Klang Valley. The Spearman correlation test indicate that there was strong significant relationship between all the locations (> 0.7; p < 0.001) and moderate relationship between Petaling Jaya-Kajang and Kajang-Shah Alam (< 0.7; p < 0.001). The principal component analysis (PCA) identifies all four locations have been affected by PM10 which were determined as one of the pollutant that deteriorated the air quality. Cluster analysis (CA) has classified the PM10 pattern into three (3) different classes; Class 1 (Klang), Class 2 (Petaling Jaya and Kajang) and Class...

Irregularities in rainfall behaviour has been characteristically visible in semi-arid climate par... more Irregularities in rainfall behaviour has been characteristically visible in semi-arid climate particularly in the tropics. Trends and variations have been used as proxies in detecting the presence of irregularities in climatic variables such as rainfall. Thirty six years (1980-2015) of data obtained from Nigerian Meteorological Agency (NIMET) were used for the present study. Multivariate statistics such as ANOVA and Cluster Analysis were used for assessing variations between and within the data mean. However, Mann-Kendall trend test was applied for trend detection. The ANOVA results showed significant variation in rainfall [F (3, 140) = 67.012, P < .05], between the stations. The cluster analysis produces two classes for rainfall indicating that rainfall is less variable spatially. Mann-Kendall trend test result shows an insignificant annual increasing trend in rainfall. However, the monthly series showed varied trend results consisting of significantand insignificant increasing ...

This study was initiated to determine the heavy metals in particulate matter (PM10) in three samp... more This study was initiated to determine the heavy metals in particulate matter (PM10) in three sampling sites with different traffic density: high (CH), medium (CM) and low density (CL) density traffic, PM10 Samples were collected from June to July 2014 during the southwest monsoon using a high volume sampler. The results showed that the PM10 mean levels were significantly higher in CH and CM (207.63 and 164.92 μg/m3) than the CL (90.09 μg/m3). The mean quantity of heavy metals in PM10 was in the order Ba>Zn>Pb>Mn > Cr > As. The highest level of these heavy metals was recorded at CH followed by CM and CL except the mean level of As, which was recorded as being higher compared to CH. Based on the correlation and enrichment analyses, the heavy metals could be divided into two source emissions in the study area – Crustal and non-crustal. Among the heavy metals, As, Pb, Zn and Ba were found to be highly enriched in the atmospheric particulate matter, Cr showed a high EF in ...

The spatiotemporal dynamics of temperature as well as rainfall have received greater attention fr... more The spatiotemporal dynamics of temperature as well as rainfall have received greater attention from the scientific communities. This study analysed temperature variability in the three granary areas of Peninsular Malaysia using descriptive statistics, parametric (least square regression) and non-parametric (MannKendall and Sen’s slope estimator). The study identified significant warming trend in the annual mean maximum temperature in two of the study areas, i.e. Subang Jaya and Kota Bharu. Also significant warming trend was detected in the annual minimum temperature and significant increasing trend in some of the monthly maximum and minimum temperatures for all the three stations. Also the result reveals spatial and temporal variation in both the maximum and minimum temperature at annual, monthly and seasonal scales. For the annual scale maximum temperature, this study identified a warming trend for the two stations with about 0.014oC per year (1.4oC per 100 years).

Traffic has greatly contributed to the socio-economic development as well as its inherent environ... more Traffic has greatly contributed to the socio-economic development as well as its inherent environmental impacts. This study estimated the emission of PM10 from the exhaust and nonexhaust, particularly from the use different type of vehicles in Klang valley region. The total PM10 emission from the region was calculated based on US-EPA and the EEA methodologies. Arc GIS is one of the most suitable methods to estimate the total PM10 emission and split between different vehicle types as it is determined by the kilometer covered for each vehicle category. The inventory is further used for traffic account, activity data and a domain size of 50 km×50 km, with cell resolution of 1km × 1km to spatially disaggregate these emissions. The results show that nearly 54% of the PM10 emitted in the region emitted from cars. The results also revealed that nearly 61% of the PM emissions emitted from exhaust. Exhaust and Non-exhaust PM10 emissions are higher in the central part of the Klang Valley, an ...

The study assessed the seasonal potential effect of temperature and rainfall variability on MR219... more The study assessed the seasonal potential effect of temperature and rainfall variability on MR219 using Ceres rice model v4.6.1.0 of the DSSAT modelling system. The model simulated sensibly rice yield with RMSPE OF 8.9%, with D- Index for grain yield of 0.99. However, the simulated yield positively correlates with observed yield (r = 0.715; p < .05), while the coefficient of determination (r2 = 0.511). The model predicted changes in rice yield in all the three granary areas with varying degrees of gains and losses in the two seasons. The result from sensitivity analysis showed that during the main season +10C rise in the maximum temperature caused decrease in yield from -0.2 to -4.5% for MADA and KADA.A rise in maximum temperature up to +50C caused decrease in the yield ranging from -3.3 to -14.3 % for all the areas. Minimum temperature increase of +10C resulted in decrease in the yield ranging from -1.3 to -3.5%. During the off season, +10C increase in temperature caused decreas...

Natural and anthropogenic aerosols varied extremely within space and time and affect the global r... more Natural and anthropogenic aerosols varied extremely within space and time and affect the global radiation balance, and influence climatic changes. The objectives of this paper are to evaluate and characterize the dispersion of aerosols in the tropical region of Peninsular Malaysia using MODerate Resolution Imaging Spectro-radiometer (MODIS) measurements. The MODIS sensors on board the Terra satellite which enables remote sensing of aerosols at high special resolution and daily global coverage of data. This paper demonstrates the capability of MODIS to show the distribution of aerosol optical thickness (AOT) over the study area. Spectral characterizers of AOT measured over Peninsular Malaysia for the period 2005 – 2007 are analyzed to understand the variability of the AOT in different seasons and location. The result showed low values on wet season and high values during the dry season for case some days. For the Correlations of the MODIS-AOT with the ground-based particulate matter ...

Climate changes greatly affect agricultural crop production and the associated farming community.... more Climate changes greatly affect agricultural crop production and the associated farming community. The magnitude of the climatic stressor, the sensitivity and capacity of the affected communities to adapt with such stressors affect farmer vulnerability. This study assessed the vulnerability of paddy farmers to climate change variability in Peninsular Malaysia. The study employed an integrated vulnerability assessment approach using three component of vulnerability i.e. exposure, sensitivity and adaptive capacity. Trend analysis was conducted using Mann – Kendall to detect temperature and rainfall variability from 1981- 2014. DSSAT Ceres- rice model was used to predict rice yield for the study areas from 2016 until 2035 and determine the sensitivity of rice yield to temperature and rainfall changes. Household survey was conducted using multi- stage systematic random sampling on 450 sampled respondents to measure their adaptive capacity. Trend analysis shows that annual maximum tempera...

It is no longer contentious that climate change has a serious impact on agriculture for the past ... more It is no longer contentious that climate change has a serious impact on agriculture for the past decades with varying consequences across the globe. These consequences are beneficial to some areas while others the story is disastrous. Therefore, estimating the impact of climate change variability has been the onus of many academic and professional researchers using various methods and approaches such as the partial equilibrium models or the economy-wide models. This review paper therefore, highlights on the various methods and approaches use to estimate the impact of climate change variability on crop production and further reviewed past empirical studies with a view to, (a) understanding the merits and demerits of each method and approach; (b) understanding the regional spread of the past research directions and current knowledge across the globe including Malaysia. The paper concluded by drawing attention to the need in paradigm shift. Refocusing future research efforts toward int...

IJOABS, 2021

Sensitivity of paddy rice to climatic perturbation makes paddy farmers to be vulnerable to climat... more Sensitivity of paddy rice to climatic perturbation makes paddy farmers to be vulnerable to climate change and variability, this resulted to the decline in paddy productivity and reduction in farmers’ income, thereby exacerbating the socio- economic wellbeing and poverty level of the farmers in Malaysia. Tackling vulnerability to climate change through effective policy action requires understanding of farmers’ adaptive capacity. This study analysed adaptive capacity of the paddy farmers and factors that causes differences in the farmers’ adaptive capacity in the study areas. Paddy farmers’ adaptive capacity levels were determined using a composite index score by linearly aggregating the farmers’ five capital indicators (human, physical, financial, social, and management capitals). The study showed that adaptive capacity index scores of the entire respondents’ ranges from -0.289 to 0.392 with Mean of -0.003 and standard deviation 0.174. About 200 (44.4%) of the respondent have low adaptive capacity, 144 (32.0%) have moderate adaptive capacity, while 106 (23.6%) have high adaptive capacity. Moreover, adaptive capacity as a component of vulnerability has immediate policy implications, in that its improvement reduces the sensitivity levels of the paddy farmers to climate change variability. As such, it is important to evolve national climate change adaptation policy that will guide policy makers to address region specific needs of the paddy farmers. The policy options should involve educating young workforce to embrace paddy farming. More extension services to enhance the skill of the old-aged farmers. Provide access to more financial capital for investment in education etc.

Polish Journal of Environmental Studies

This study was conducted to determine heavy metal concentrations in particulate matter (pM 10) an... more This study was conducted to determine heavy metal concentrations in particulate matter (pM 10) and the source identification in the areas affected by traffic during the southwest monsoon from June to July 2014. Collection of the particulate samples was done at three sampling sites that have varying traffic densities (high, medium, and low). Samples were collected using a high-volume air sampler. Heavy metals in the particulate matter (pM 10) were assessed with inductively coupled plasma mass spectrometry. The results show that the mean concentrations of pM 10 for high-, medium-, and low-density traffic were found to be 207.63±7.82, 164.92±10.68, and 90.09±20.70 µg m-3 , respectively. The concentrations in high-and mediumdensity areas were found to be significantly higher than 150 µg m-3 for 24 hrs as per Recommended Malaysian Air Quality Guidelines (RMAQG). The heavy metals found were dominated by Ba and Fe, followed by Cu > V> Zn > pb > Mn > Cr> As > Ni >Cd > Co. A comparison of the concentrations of heavy metals with the United State Environmental protection Agency (USEpA) and World Health Organization (WHO) guidelines revealed that As was higher than the standards in high-and medium-density areas. Cluster analysis (CA) and principal component analysis (pCA) were employed in the identification of the sources of metals for high-, medium-, and low-traffic densities. The CA identified three clusters for high-, medium-, and low-traffic densities, while pCA extracted four sources for high-, medium-, and low-traffic densities and the major pollution sources identified were vehicle exhaust emission, non-exhaust emission (brake and tire wear), and re-suspension dust.

Polish Journal of Environmental Studies

Global Journal of HUMAN-SOCIAL SCIENCE: B Geography, Geo-Sciences, Environmental Science & Disaster Management, 2020

The spatiotemporal dynamics of temperature as well as rainfall have received greater attention fr... more The spatiotemporal dynamics of temperature as well as rainfall have received greater attention
from the scientific communities. This study analysed temperature variability in the three granary areas of
Peninsular Malaysia using descriptive statistics, parametric (least square regression) and non-parametric
(Mann- Kendall and Sen’s slope estimator). The study identified significant warming trend in the annual
mean maximum temperature in two of the study areas, i.e. Subang Jaya and Kota Bharu. Also significant
warming trend was detected in the annual minimum temperature and significant increasing trend in some
of the monthly maximum and minimum temperatures for all the three stations. Also the result reveals
spatial and temporal variation in both the maximum and minimum temperature at annual, monthly and
seasonal scales. For the annual scale maximum temperature, this study identified a warming trend for the
two stations with about 0.014oC per year (1.4oC per 100 years).
Keywords: temperature trends, mann- kendall, sen’s slope estimator, peninsular malaysia.

This study was conducted to determine heavy metal concentrations in particulate matter (PM10) and... more This study was conducted to determine heavy metal concentrations in particulate matter (PM10) and the source identification in the areas affected by traffic during the southwest monsoon from June to July 2014. Collection of the particulate samples was done at three sampling sites that have varying traffic densities (high, medium, and low). Samples were collected using a high-volume air sampler. Heavy metals in the
particulate matter (PM10) were assessed with inductively coupled plasma mass spectrometry. The results show that the mean concentrations of PM10 for high-, medium-, and low-density traffic were found to be 207.63±7.82, 164.92±10.68, and 90.09±20.70 μg m-3, respectively. The concentrations in high- and medium density areas were found to be significantly higher than 150 μg m-3 for 24 hrs as per Recommended Malaysian Air Quality Guidelines (RMAQG). The heavy metals found were dominated by Ba and Fe, followed by Cu > V> Zn > Pb > Mn > Cr> As > Ni >Cd > Co. A comparison of the concentrations of heavy metals with the United State Environmental Protection Agency (USEPA) and World Health Organization (WHO) guidelines revealed that As was higher than the standards in high- and medium-density areas. Cluster analysis (CA) and principal component analysis (PCA) were employed in the identification of the sources of metals for high-, medium-, and low-traffic densities. The CA identified three clusters for high-, medium-, and low-traffic densities, while PCA extracted four sources for high-, medium-, and low-traffic densities and the major pollution sources identified were vehicle exhaust emission, non-exhaust emission (brake and tire wear), and re-suspension dust.

Keywords: particulate matter, PM10, heavy metals, multivariate techniques, source apportionment

Irregularities in rainfall behavior has been characteristically visible in semi-arid climate part... more Irregularities in rainfall behavior has been characteristically visible in semi-arid climate particularly in the tropics. Trends and variations have been used as proxies in detecting the presence of irregularities in climatic variables such as rainfall. Thirty six years (1980-2015) of data obtained from Nigerian Meteorological Agency (NIMET) were used for the present study. Multivariate statistics such as ANOVA and Cluster Analysis were used for assessing variations between and within the data mean. However, Mann-Kendall trend test was applied for trend detection. The ANOVA results showed significant variation in rainfall [F (3, 140) = 67.012, P < .05], between the stations. The cluster analysis produces two classes for rainfall indicating that rainfall is less variable spatially. Mann-Kendall trend test result shows an insignificant annual increasing trend in rainfall. However, the monthly series showed varied trend results consisting of significant and insignificant increasing and decreasing trends.

International Journal of Applied Environmental Sciences, 2017

The study assessed the seasonal potential effect of temperature and rainfall variability on MR219... more The study assessed the seasonal potential effect of temperature and rainfall variability on MR219 using Ceres rice model v4.6.1.0 of the DSSAT modelling system. The model simulated sensibly rice yield with RMSPE OF 8.9%, with D-Index for grain yield of 0.99. However, the simulated yield positively correlates with observed yield (r = 0.715; p < .05), while the coefficient of determination (r 2 = 0.511). The model predicted changes in rice yield in all the three granary areas with varying degrees of gains and losses in the two seasons. The result from sensitivity analysis showed that during the main season +1 0 C rise in the maximum temperature caused decrease in yield from-0.2 to-4.5% for MADA and KADA.A rise in maximum temperature up to +5 0 C caused decrease in the yield ranging from-3.3 to-14.3 % for all the areas. Minimum temperature increase of +1 0 C resulted in decrease in the yield ranging from-1.3 to-3.5%. During the off season, +1 0 C increase in temperature caused decrease in yield from-0.5 to-2.3% for MADA and IADA. A rise in +3 0 C maximum temperature caused decrease in the yield ranging from-2.5 to-7.5% for all the areas. While +1 0 C rise in minimum

IOP Conference Series: Earth and Environmental Science, 2014

Malaysian Journal of Analytical Science, 2016

IJOABS, 2021

Sensitivity of paddy rice to climatic perturbation makes paddy farmers to be vulnerable to climat... more Sensitivity of paddy rice to climatic perturbation makes paddy farmers to be vulnerable to climate change and variability, this resulted to the decline in paddy productivity and reduction in farmers’ income, thereby exacerbating the socio- economic wellbeing and poverty level of the farmers in Malaysia. Tackling vulnerability to climate change through effective policy action requires understanding of farmers’ adaptive capacity. This study analysed adaptive capacity of the paddy farmers and factors that causes differences in the farmers’ adaptive capacity in the study areas. Paddy farmers’ adaptive capacity levels were determined using a composite index score by linearly aggregating the farmers’ five capital indicators (human, physical, financial, social, and management capitals). The study showed that adaptive capacity index scores of the entire respondents’ ranges from -0.289 to 0.392 with Mean of -0.003 and standard deviation 0.174. About 200 (44.4%) of the respondent have low adaptive capacity, 144 (32.0%) have moderate adaptive capacity, while 106 (23.6%) have high adaptive capacity. Moreover, adaptive capacity as a component of vulnerability has immediate policy implications, in that its improvement reduces the sensitivity levels of the paddy farmers to climate change variability. As such, it is important to evolve national climate change adaptation policy that will guide policy makers to address region specific needs of the paddy farmers. The policy options should involve educating young workforce to embrace paddy farming. More extension services to enhance the skill of the old-aged farmers. Provide access to more financial capital for investment in education etc.

Polish Journal of Environmental Studies

Global Journal of HUMAN-SOCIAL SCIENCE: B Geography, Geo-Sciences, Environmental Science & Disaster Management, 2020

The spatiotemporal dynamics of temperature as well as rainfall have received greater attention fr... more The spatiotemporal dynamics of temperature as well as rainfall have received greater attention
from the scientific communities. This study analysed temperature variability in the three granary areas of
Peninsular Malaysia using descriptive statistics, parametric (least square regression) and non-parametric
(Mann- Kendall and Sen’s slope estimator). The study identified significant warming trend in the annual
mean maximum temperature in two of the study areas, i.e. Subang Jaya and Kota Bharu. Also significant
warming trend was detected in the annual minimum temperature and significant increasing trend in some
of the monthly maximum and minimum temperatures for all the three stations. Also the result reveals
spatial and temporal variation in both the maximum and minimum temperature at annual, monthly and
seasonal scales. For the annual scale maximum temperature, this study identified a warming trend for the
two stations with about 0.014oC per year (1.4oC per 100 years).
Keywords: temperature trends, mann- kendall, sen’s slope estimator, peninsular malaysia.

Keywords: particulate matter, PM10, heavy metals, multivariate techniques, source apportionment

International Journal of Applied Environmental Sciences, 2017

The study assessed the seasonal potential effect of temperature and rainfall variability on MR219... more The study assessed the seasonal potential effect of temperature and rainfall variability on MR219 using Ceres rice model v4.6.1.0 of the DSSAT modelling system. The model simulated sensibly rice yield with RMSPE OF 8.9%, with D-Index for grain yield of 0.99. However, the simulated yield positively correlates with observed yield (r = 0.715; p < .05), while the coefficient of determination (r 2 = 0.511). The model predicted changes in rice yield in all the three granary areas with varying degrees of gains and losses in the two seasons. The result from sensitivity analysis showed that during the main season +1 0 C rise in the maximum temperature caused decrease in yield from-0.2 to-4.5% for MADA and KADA.A rise in maximum temperature up to +5 0 C caused decrease in the yield ranging from-3.3 to-14.3 % for all the areas. Minimum temperature increase of +1 0 C resulted in decrease in the yield ranging from-1.3 to-3.5%. During the off season, +1 0 C increase in temperature caused decrease in yield from-0.5 to-2.3% for MADA and IADA. A rise in +3 0 C maximum temperature caused decrease in the yield ranging from-2.5 to-7.5% for all the areas. While +1 0 C rise in minimum

Agricultural crop production is vulnerable to the effects of changing temperature and rainfall. T... more Agricultural crop production is vulnerable to the effects of changing temperature and rainfall. This study assess the spatio-temporal vulnerability of rice MR219 to the effect of temperature and rainfall changes in MADA, IADA, BLS and KADA granary areas of Peninsular Malaysia. The study predicted changes in yield between 2016 up to 2035 using DSSAT CERES-rice model v4.6.1.0. Genetic coefficients of the rice cultivar used in the model was determined iteratively. To validate the model, daily observatory weather data including both minimum and maximum temperature, solar radiation, rainfall and relative humidity spanning for the period 2001 to 2014 for Subang Jaya meteorological station were obtained from Malaysia Meteorological Department and used in the model to simulate yield for the Main season at IADA, Barat Laut Selangor. The study shows marked seasonal and spatial variation in the predicted rice yield. An analysis of variance shows a significant difference between granary areas during both main and off seasons with F (2, 57) = 71.976, p = .000 and F (2, 57) = 43.995, p = .000 respectively. However, multiple comparison using Turkey HSD reveals a significant difference between granary areas for both seasons, with exception of IADA and MADA which shows no significant difference in predicted yield during off season.

This study identifies the major methods used by farmers to adapt to climate change in the semiari... more This study identifies the major methods used by farmers to adapt to climate change in the semiarid zone of northeastern Nigeria, and the factors that affect their choice of method. The methods identified include soil conservation, change in planting date, tree planting, irrigation, and the use of different crop varieties. Results from the Multivariate probit choice model employed indicate that the level of education, farming experience, household size, farm income, non-farm income, access to extension and credit; information on climate, social capital, and livestock ownership all influence farmers' choices of adaptation methods.