Indonesian Institute of Sciences

About: Indonesian Institute of Sciences is a facility organization based out in Jakarta, Indonesia. It is known for research contribution in the topics: Population & Biology. The organization has 4795 authors who have published 10544 publications receiving 76990 citations. The organization is also known as: Indonesian Institute of Sciences Cibinong, Indonesia.

Development of Water Quality Parameter Retrieval Algorithms for Estimating Total Suspended Solids and Chlorophyll-A Concentration Using LANDSAT-8 Imagery at Poteran Island Water

Abstract: The Landsat-8 satellite imagery is now highly developed compares to the former of Landsat projects. Both land and water area are possibly mapped using this satellite sensor. Considerable approaches have been made to obtain a more accurate method for extracting the information of water area from the images. It is difficult to generate an accurate water quality information from Landsat images by using some existing algorithm provided by researchers. Even though, those algorithms have been validated in some water area, but the dynamic changes and the specific characteristics of each area make it necessary to get them evaluated and validated over another water area. This paper aims to make a new algorithm by correlating the measured and estimated TSS and Chla concentration. We collected in-situ remote sensing reflectance, TSS and Chl-a concentration in 9 stations surrounding the Poteran islands as well as Landsat 8 data on the same acquisition time of April 22, 2015. The regression model for estimating TSS produced high accuracy with determination coefficient ( R 2 ), NMAE and RMSE of 0.709; 9.67 % and 1.705 g/m 3 respectively. Whereas, Chla retrieval algorithm produced R 2 of 0.579; NMAE of 10.40% and RMSE of 51.946 mg/m 3 . By implementing these algorithms to Landsat 8 image, the estimated water quality parameters over Poteran island water ranged from 9.480 to 15.801 g/m 3 and 238.546 to 346.627 mg/m 3 for TSS and Chl-a respectively.

Collider constraints on a dark matter interpretation of the XENON1T excess

Abstract: In light of the excess in the low-energy electron recoil events reported by XENON1T, many new physics scenarios have been proposed as a possible origin of the excess. One possible explanation is that the excess is a result of a fast moving dark matter (DM), with velocity $$v\sim $$ 0.05–0.20 and mass between 1 MeV and 10 GeV, scattering off an electron. Assuming the fast moving DM-electron interaction is mediated by a vector particle, we derive collider constraints on the said DM-electron interaction. The bounds on DM-electron coupling is then used to constrain possible production mechanisms of the fast moving DM. We find that the preferred mass of the vector mediator is relatively light ( $$\lesssim $$ 1 GeV) and the coupling of the vector to the electron is much smaller than the coupling to the fast moving DM.

The physical, mechanical and durability properties of sorghum bagasse particleboard by layering surface treatment

Abstract: The decrease of wood supply leads to find out the alternative raw material for particleboard production derived from non-woody cellulose materials, one of the promising material is sorghum bagasse. However, the strength properties of particleboard manufactured from this biomass tend to be low. This research was to evaluate physical, mechanical and durability properties of sorghum bagasse-particleboard (SBP) which was layered by several materials. Previously, sorghum bagasse as particle board core and materials for layers such as woven of bamboo bark, woven of barkless bamboo, bamboo strand, Meranti and Eucalyptus veneer were oven dried at 103 °C to reach 4% moisture content with 10% Urea formaldehyde resin. After particle and adhesive blending step, furnish was used as core with layer materials as surface. Subsequently, mat was pressed at 130 °C for 10 min with 30 kg cm−2. Physical and mechanical properties evaluation refers to JIS A 5908-2003, while their durability properties were evaluated by grave yard test. The results showed that surface layer treatment improved the bending properties presented by increasing of modulus of rupture and modulus of elasticity value of surface layer treatment of SBP compared to untreated ones. However, their thickness swelling has not been met standard of JIS A 5908-2003 yet. Furthermore, surface layer treatment with woven of barkless bamboo showed the best physical, mechanical, and durability properties.

Distribution of total mercury and methylmercury around the small-scale gold mining area along the Cikaniki River, Bogor, Indonesia

Abstract: This study investigates the distribution of total mercury (T-Hg) and methylmercury (MeHg) in the soil and water around the artisanal and small-scale gold mining (ASGM) area along the Cikaniki River, West Java, Indonesia. The concentration of T-Hg and MeHg in the forest soil ranged from 0.07 to 16.7 mg kg−1 and from <0.07 to 2.0 μg kg−1, respectively, whereas it ranged from 0.40 to 24.9 mg kg−1 and from <0.07 to 56.3 μg kg−1, respectively, in the paddy field soil. In the vertical variation of the T-Hg of forest soil, the highest values were observed at the soil surface, and these values were found to decrease with increasing depth. A similar variation was observed for MeHg and total organic carbon content (TOC), and a linear relationship was observed between them. Mercury deposited on the soil surface can be trapped and retained by organic matter and subjected to methylation. The slope of the line obtained for the T-Hg vs. TOC plot became larger near the ASGM villages, implying a higher rate of mercury deposition in these areas. In contrast, the plots of MeHg vs. TOC fell along the same trend line regardless of the distance from the ASGM village. Organic carbon content may be a predominant factor in controlling MeHg formation in forest soils. The T-Hg concentration in the river water ranged from 0.40 to 9.6 μg L−1. River water used for irrigation can prove to be a source of mercury for the paddy fields. The concentrations of Hg0 and Hg2+ in river water showed similar variations as that observed for the T-Hg concentration. The highest Hg0 concentration of 3.2 μg L−1 can be attributed to the waste inflow from work sites. The presence of Hg0 in river water can become a source of mercury present in the atmosphere along the river. MeHg concentration in the river water was found to be 0.004–0.14% of T-Hg concentration, which was considerably lower than the concentrations of other Hg species. However, MeHg comprised approximately 0.2% of the T-Hg in paddy field soil. Mercury deposited from the atmosphere and the river water can be subjected to methylation. Paddy fields are very important ecosystems; therefore, the effect of MeHg on these ecosystems and human beings should be further investigated.