Search Results (311)

One of the main obstacles to producing natural rubber-modified asphalt is the difficulty of mixing Technical Specification Natural Rubber (TSNR) or its compounds with asphalt, leading to long mixing times and high costs. This study aims to evaluate the use of 60/70 penetration asphalt as a plasticizer to accelerate the mixing process and improve the rheological properties of modified asphalt using Technical Specification Natural Rubber (TSNR). The production process for technical specification natural rubber-modified asphalt involves two stages: the production of the technical specification natural rubber compound (CTSNR) and the production of CTSNR-based modified asphalt (CTSNRMA). The CTSNR production process begins with mastication of technical specification natural rubber (TSNR), followed by the addition of activators (zinc oxide, stearic acid), accelerators (Mercaptobenzothiazole sulfenamide (MBTS)), antioxidants (2,2,4-Trimethyl-1,2-dihydroquinoline (TMQ)), and 60/70 penetration asphalt as a plasticizer (at concentrations of 30%, 40%, and 50%). After homogeneous mixing for 30–60 min, the CTSNR is diluted 5–10 mm for the next mixing stage with hot asphalt at 160–170 °C. The best results of this study showed that CTSNR-modified asphalt with 4% rubber content and 50% plasticizer (CTSNRM-450) successfully reduced the mixing time to 16 min, making it more efficient than the traditional method, which takes up to 180 min. The addition of asphalt plasticizer decreased penetration to 35.6 dmm and increased the softening point to 55.4 °C. The CTSNRMA-440 formula, with 4% rubber content and 40% plasticizer, produced the best results in terms of storage stability, meeting the ASTM D5892 standard with a softening-point difference of 0.95 °C, which is well below the threshold of 2.2 °C. The CTSNRMA-440 sample achieved a Performance Grade (PG) of 76, suitable for hot-climate conditions, with a significant reduction in mixing time, greater stability, and increased resistance to high temperatures. Full article

Peatlands provide essential ecological services but are highly vulnerable to degradation from drainage, leading to greenhouse gas emissions, land subsidence, and increased fire susceptibility. This study investigates peat hydrology and its relationship to fire risk in a fire-prone area in South Sumatra, Indonesia. Groundwater levels and soil moisture were continuously monitored using automated loggers, and recession analysis quantified their rates of decline. Multispectral drone imagery (NDVI, NDWI) over a 44.1-ha area assessed vegetation and surface wetness, while fire occurrences (2019–2024) were analyzed using the Fire Information for Resource Management System (FIRMS). During a 58-day dry period, groundwater depth reached 78.5 cm with a recession rate of 9.68 mm day⁻¹, while soil moisture decreased by 0.00291 m³ m⁻³ per day over 27 consecutive dry days. Drone imagery revealed that unhealthy and dead grass covered nearly 90% of the site, although wetness remained moderate (NDWI = 0.02–0.58). FIRMS data indicated that rainfall below 2000 mm year⁻¹ and prolonged dry spells (>30 days) strongly trigger peat fires. These findings correspond with early-warning model outputs based on soil moisture recession and ignition thresholds. Maintaining a high groundwater level is, therefore, crucial for reducing peat fire vulnerability under extended dry conditions. Full article

This study examines how socialization costs, inspection costs, collection costs, motor vehicle tax rates (Pajak Kendaraan Bermotor, PKB), vehicle ownership transfer tax rates (Bea Balik Nama Kendaraan Bermotor, BBNKB), the Corruption Perception Index (CPI), and the Indonesian Digital Society Index (Indeks Masyarakat Digital Indonesia, IMDI) influence regional tax compliance across 34 provinces in Indonesia, using secondary data from 2020 to 2024. Guided by Fiscal Federalism, Tax Optimization Theory, and the Fischer Tax Compliance Model, the analysis integrates spatial regression and SWOT to capture both structural and spatial dynamics in provincial tax administration. The spatial error model reveals that socialization costs, PKB, and BBNKB significantly shape provincial tax compliance. At the same time, the other variables show no measurable effect. Spatial clustering indicates High–High compliance in Central Java, Low–Low compliance in South Sumatra and Lampung, and Low–High compliance in North Sumatra. The SWOT assessment places Indonesia’s provincial tax compliance strategy in Quadrant I, suggesting strong institutional capacity and substantial external opportunities to support aggressive improvement strategies. This study contributes by providing province-wide empirical evidence on the fiscal and administrative determinants of compliance and by incorporating collection costs and spatial relationships into the analysis. Policy implications include strengthening targeted socialization, improving rate-setting mechanisms, and expanding digital reporting systems to enhance taxpayer understanding and administrative transparency. Full article

BU–MIT whistler wave injection experiments, which were conducted at Arecibo Observatory, started with the joint US–USSR Active Space Plasma Program Experiment on 24 December 1989. In this experiment, a satellite-borne VLF transmitter injected radio waves at the frequency and power of 10 kHz and 10 kW. A series of controlled whistler wave experiments with the Arecibo HF heater were subsequently carried out during 1990–1998 until the HF heater was damaged by Hurricane Georges in 1998. In these ionospheric HF heating experiments, 28.5 kHz whistler waves were launched from the nearby naval transmitter (code-named NAU) located at Aguadilla, Puerto Rico. HF heater waves were used to create ionospheric ducts (in the form of parallel-plate waveguides) to facilitate the entry of NAU whistler waves from the neutral atmosphere into the ionosphere. Conjugate whistler wave propagation experiments were conducted between Arecibo, Puerto Rico and Trelew, Argentina in 1997. After 1999, whistler wave experiments in the absence of an HF heater had been conducted. Naturally-occurring large-scale ionospheric irregularities due to spread F or Traveling Ionospheric Disturbances (TIDs) were relied on to guide NAU launched 40.75 kHz whistler waves to propagate from the ionosphere further into the radiation belts, to cause 390 keV charged-particle precipitation. A train of TIDs, resulting from the 9.2 Mw earthquake off the west coast of Sumatra, Indonesia, was observed in our 26 December 2004 Arecibo experiments, about a day after the earthquake-launched tsunami waves traveled across the Indian Ocean, then into remote parts of the Atlantic Ocean. The author’s recent research efforts, motivated by Arecibo experiments, focus on Solar Powered Microwave Transmitting Systems, to simulate Solar Energy Harvesting via Solar Power Satellite (SPS) (also known as Space Based Solar Power (SBSP)) These experiments involved a large number of the author’s BU and MIT students working on theses and participating in the Undergraduate Research Opportunities Program (UROP), in collaboration with other colleagues at several universities and national laboratories. Full article

This paper examines community resilience in addressing clean water scarcity in Salaon Toba Village, Ronggur Nihuta Subdistrict, Samosir District, North Sumatra, Indonesia. Although the Lake Toba region is abundant in water resources, many surrounding settlements continue to face difficulties in accessing safe and reliable water. Using a descriptive qualitative method, the study engaged 20 informants through in-depth interviews and direct observations to explore the challenges and strategies adopted by local residents. The findings reveal that, despite the village’s proximity to Lake Toba, geographical and geological conditions—such as rocky highland terrain—significantly limit water availability, especially during the rainy season. To cope with these constraints, communities employ diverse adaptive strategies, including purchasing water transported from Lake Toba, harvesting rainwater from rooftops, constructing large storage tanks inside and outside homes, implementing strict water-saving routines, and organizing water-related responsibilities along gender lines. While Salaon Toba has access to multiple water sources—springs, rainwater, Lake Toba, and Lake Pea Porohan—their full utilization remains constrained by technical limitations, cultural restrictions, and inadequate infrastructure. These strategies highlight the community’s agency in sustaining daily needs, yet also underline the urgent need for government intervention to ensure equitable and sustainable access to clean water. The study emphasizes the importance of inclusive policies aligned with Sustainable Development Goal 6 [Clean Water and Sanitation] to strengthen both infrastructure and community resilience in facing climate-induced water challenges. Full article

Peatlands store approximately 30% of global terrestrial carbon, and tropical peatlands contribute 10%–30% of the total peatland carbon storage. Indonesia holds approximately 15% of this resource. Given the rapid degradation of these ecosystems, the Indonesian government has promoted revegetation, identifying Calophyllum inophyllum L. (Tamanu) as a promising restoration species. However, long-term studies on Tamanu performance and optimal environmental conditions in actual peatland settings are lacking. This study aimed to identify the environmental characteristics conducive to Tamanu growth. We planted Tamanu at Perigi in South Sumatra and Buntoi in Central Kalimantan and monitored its growth over a five-year period. We assessed the soil properties and hydrological conditions at both sites. Results revealed that Tamanu trees at the Perigi site, with higher soil nutrient levels, initially exhibited greater root collar diameter, height, and stem volume compared to those at Buntoi. However, prolonged flooding in Perigi caused complete mortality at 60 months. In contrast, despite lower soil nutrient levels, the Buntoi site maintained a survival rate of 52% because of the more stable water levels. These findings suggest that hydrological management is more critical than soil nutrient conditions for the long-term survival of Tamanu in tropical peatlands, informing effective peatland restoration strategies. Full article

This study introduces an IoT-enabled smart greenhouse system tailored for rice cultivation and designed as a controlled experimental platform to evaluate fertilizer application methods. Traditional greenhouse farming often struggles with unpredictable weather, pest infestations, and inefficient resource use. To overcome these challenges, the proposed system optimizes environmental conditions and enables precise monitoring and control through the Thingsboard IoT platform, which tracks temperature, humidity, and sunlight intensity in real time. The cultivation process involved Inceptisol soil preparation, slurrying, fertilization, seeding, transplantation, and continuous monitoring. The novelty lies in its dual-purpose design, enabling both cultivation and structured agronomic experimentation under identical environmental conditions. The system enables both rice cultivation and comparative testing of nano-silica fertilizer applied via root (soil) and foliar (leaf) methods. Automated temperature control (maintaining 20–36.5 °C) and humidity regulation (10–85% RH) with a mist blower response time under 5 s ensured consistent conditions. Sensor accuracy was validated with deviations of 0.4% (±0.11 °C) and 0.77% (±0.5% RH). Compared to conventional setups, this system achieved superior environmental stability and control precision, improving experimental reproducibility. Its integration potential with machine learning models opens new possibilities for forecasting plant responses based on historical data. Overall, the study demonstrates how advanced technology can enhance agricultural precision, sustainability, and research reliability. Full article

The Ultra-Micro (UMi) financing program represents a significant public sector innovation in Indonesia’s approach to poverty alleviation and financial inclusion. Initially conceived as a social assistance initiative, UMi has evolved into a strategic government intervention designed to transform impoverished individuals into entrepreneurs. This shift reflects a policy innovation that redefines the role of the state from passive welfare provider to active enabler of economic participation. Despite ambitious goals, its implementation and impact face scrutiny. This study employed an exploratory qualitative approach through individual interviews with elite participants and debtors of UMi. The data used triangulation from documentation, observation, and in-depth interviews with key informants, selected through purposive sampling. Findings indicate that the program’s implementation—anchored in government regulations and executed through non-bank financial institutions (NBFIs)—demonstrates innovative service delivery. In this study, UMi exemplifies how public sector innovation—through policy reform, institutional collaboration, and community engagement—can drive inclusive economic growth. The study provides valuable insights for policymakers, practitioners, and scholars seeking to advance financial inclusion and sustainable economic development. Full article

Palm oil is a significant product, predominantly from Indonesia and Malaysia, and is included in many products. However, oil palm (OP) plantations have been associated with deforestation and destruction of peat soil, tending to increase CO₂ in the atmosphere and contribute to climate change. The growth of OP may be affected detrimentally by climate change. Also, OP is susceptible to basal stem rot (BSR) caused by the fungus Ganoderma boninense. Previous CLIMEX-modelled scenarios have indicated decreases in suitable climate for growing OP in the future, and narrative models suggest increases in BSR. However, the climate maps show regions in Malaysia and Indonesia that were previously unsuitable, which have become highly suitable climate (HSC) areas and were previously unreported. These areas include the higher altitudes of (a) the west coast of Sumatra, (b) areas between Sarawak, Sabah, and Kalimantan, (c) the central region of Sulawesi, (d) northern West Papua, (e) and the Titiwangsa Mountains of Peninsular Malaysia. These trends are remarkable per se. The incidence of BSR will likely be low because the palms would experience HSC, making them more resistant to infection. For example, HSC is projected to increase from 0% at present to 95% by 2100, while BSR is projected to increase from 0% at present to 30% over the same time period in Sumatra. In Borneo, HSC is projected to increase from 0% at present to 95% by 2100, while BSR is projected to increase from 0% to 7% over the same time period. Higher CO₂ fertilisation may occur which would increase OP vigour again leading to greater resistance to BSR. However, many of the regions may be biodiverse and it would be unreasonable to replace them with plantations and whether these areas would be suitable for growing OP requires careful consideration. This report of increasing areas of HSC for growing OP is unique. Full article

This study aims to examine the determinants of tourist continuance intention in halal tourism in Indonesia and extend the Theory of Planned Behavior (TPB) model by incorporating sustainable tourist citizenship behavior (STCB) and tourists’ emotional events and past halal experiences to provide a rounded understanding of Muslim tourists’ revisit intentions. This quantitative study employed partial least squares structural equation modeling (PLS-SEM) to analyze the data collected from 500 Muslim tourists who visited halal destinations in West Sumatra. The findings reveal that their STCB, attitudes, subjective norms, and perceived behavioral control significantly influence their continuance intention. Moreover, the empirical findings indicate that tourists’ emotional events and past halal experiences positively affect the TPB constructs, further strengthening the behavioral outcomes. All the proposed hypotheses were supported by the model and highlight the critical roles of psychological, experiential, and behavioral factors in shaping tourist loyalty. The results of this study contribute to the theoretical advancement of halal tourism behavior and offer practical suggestions for destination management to enhance sustainable engagement and repeat visitation among Muslim travelers. Full article

Fungi in tropical ecosystems remain an understudied yet critical component of climate change mitigation, particularly within the Land Use, Land-Use Change, and Forestry (LULUCF) sector. This review highlights their dual role in reducing greenhouse gas (GHG) emissions by regulating carbon dioxide (CO₂), methane (CH₄), and nitrous oxides (N₂O) while enhancing long-term carbon sequestration. Mycorrhizal fungi are pivotal in maintaining soil integrity, facilitating nutrient cycling, and amplifying carbon storage capacity through symbiotic mechanisms. We synthesize how fungal symbiotic systems under LULUCF shape ecosystem networks and note that, in pristine ecosystems, these networks are resilient. We introduce the concept of Nature-based Culture (NbC) to describe symbiotic self-cultures sustaining ecosystem stability, biodiversity, and carbon sequestration. Case studies demonstrate how the NbC concept is applied in reforestation strategies such as AeroHydro Culture (AHC), the Integrated Mangrove Sowing System (IMSS), and the 4N approach (No Plastic, No Burning, No Chemical Fertilizer, Native Species). These approaches leverage mycorrhizal networks to improve restoration outcomes in peatlands, mangroves, and semi-arid regions while minimizing land disturbance and chemical inputs. Therefore, by bridging fungal ecology with LULUCF policy, this review advocates for a paradigm shift in forest management that integrates fungal symbioses to strengthen carbon storage, ecosystem resilience, and human well-being. Full article

This study evaluates occupational exposure to respirable particulate matter (PM2.5) and crystalline silica (c-silica) among workers in five ceramic industries in Indonesia. Personal sampling revealed that 55.3% of workers were exposed to c-silica levels exceeding the Threshold Limit Value (TLV) of 50 µg/m³, with concentrations ranging from 1.5 to 1395.3 µg/m³. PM2.5 levels reached as high as 4152.4 µg/m³ in certain production zones. Health surveys identified frequent respiratory symptoms such as shortness of breath (27.1%) and chronic cough (14.6%), with 6.4% of workers showing lung abnormalities on chest X-rays. Risk assessments based on chronic daily intake (CDI), hazard quotient (HQ), and risk quotient (RQ) revealed that 63.8% of workers faced unsafe exposure, particularly those with longer job tenures, older age, and poor compliance with personal protective equipment (PPE). To mitigate risks, the study recommends engineering controls such as more local exhaust ventilation, improved PPE usage, and administrative measures including job rotation and regular health monitoring. These findings highlight the urgent need for improved occupational health strategies in silica-intensive industries and call for further research on long-term health impacts and effective intervention programs. Full article

Indoor air pollution remains a critical health issue in the rural areas of low- and middle-income countries like Indonesia, where solid fuels are commonly used for cooking. This study assessed real-time indoor particulate matter (PM) concentrations in three rural households in Jorong V Botung, West Sumatra, using PurpleAir low-cost sensors (PurpleAir Inc., Draper, UT, USA). Mass concentrations of PM₁, PM_2.5, and PM₁₀, along with size-segregated number concentrations (0.3–10 µm), were monitored continuously over six days (30 March–4 April 2024) during the Eid al-Fitr holiday, which involves extensive cooking activities. PM_2.5 concentrations frequently exceeded 200 µg/m³, with a peak of 249.9 µg/m³ recorded during morning cooking hours. The smallest particle size (0.3–0.5 µm) dominated number concentrations, reaching up to 17,098 particles/dL, while larger particle levels were significantly lower. Strong positive correlations (r > 0.95) were observed among PM₁, PM_2.5, PM₁₀ and AQI, indicating that cooking emissions substantially contributed to indoor PM levels. The findings highlight the need for targeted interventions, including clean fuel subsidies, improved ventilation, and public awareness efforts. This study contributes critical data on indoor air quality in rural Indonesia and supports broader initiatives to reduce exposure to household air pollution in Southeast Asia. Full article

Food price volatility is a persistent challenge in Indonesia, where agriculture is central to food security and rural livelihoods. While price transmission has been studied, little is known about how volatility spreads sub-nationally in archipelagic economies with fragmented infrastructure. This study applies a Dynamic Conditional Correlation GARCH (DCC-GARCH) model to monthly rural producer price data from 2009 to 2022 for six commodities: rice, chicken, eggs, chili, cayenne, and shallots. Results show that Java functions as the core volatility transmitter, with long-run conditional correlations exceeding 0.92 in Sumatra, 0.91 in Kalimantan, and 0.90 in Papua, reflecting strong and persistent co-movements. Even in low-production regions such as Maluku, significant volatility linkages reveal structural dependence on Java. Volatility clustering is particularly intense for perishables like chili and shallots. The findings highlight the need for spatially differentiated stabilization policies, including upstream interventions in Java and cooperative-based storage systems in outer islands. This study is the first to apply a DCC-GARCH framework to rural producer price data in an archipelagic context, capturing volatility transmission across regions. Its novelty lies in linking these spillovers with regional market dependence, offering new empirical evidence and actionable insights for designing inclusive and geographically responsive food security strategies. Full article

Background: Indonesia launched a nationwide school-based HPV immunization program in August 2023. Despite this, regional disparities in vaccine uptake persist. Therefore, we undertook a study in North Sumatra Province to assess HPV vaccination coverage and analyze the main factors affecting the uptake of HPV vaccination. Methods: This study employed a mixed-methods approach and was carried out in Medan and Deli Serdang of North Sumatra Province. Quantitative data were used to examine HPV coverage rates among school-aged girls in 2024, while qualitative interviews with parents, teachers, and health officers explored administrative, social, and behavioral barriers and facilitators. Results: In 2024, HPV vaccine coverage in Deli Serdang reached 62.09%, while Kota Medan lagged behind at just 27.20%. High-coverage schools in the Galang subdistrict benefited from proactive engagement between Puskesmas (community health clinics) and parents. In contrast, lower-coverage areas experienced logistical and communication challenges. Parents expressed a preference for face-to-face communication over written consent forms and emphasized the importance of clear, empathetic messaging. Conclusions: The stark contrast in coverage—particularly the low uptake in urban Kota Medan—highlights the need for more responsive and localized implementation strategies. Strengthening direct communication, addressing administrative inefficiencies, and fostering trust through tailored community engagement are critical. These findings suggest a need for targeted improvements in urban settings and further research across diverse regions to inform policy development and strategies for improved coverage of HPV vaccinations. Full article