446494 research outputs found
Sort by
Probing neutral outflows in
No full textUsing deep JWST/NIRSpec spectra from the Blue Jay survey, we performed the first systematic investigation of neutral gas content in massive galaxies at Cosmic Noon based on the Ca II H, K absorption lines. We analyzed a sample of nine galaxies at 1.8 10.6, for which we detected neutral gas absorption both in Ca II and in Na I. After removing the stellar continuum using the best-fit model obtained with Prospecto
Chronology of our Galaxy from
No full textThe Milky Way’s inner region is dominated by a stellar bar and a boxy-peanut-shaped bulge. However, which stellar populations inhabit the inner Galaxy or how star formation proceeded there is still unknown. The difficulty in studying these stars stems from their location in dense regions that are strongly impacted by extinction and crowding effects. In this work we used star formation histories computed in the solar neighbourhood via Gaia colour-magnitude diagram fitting to shed light on the evolution of the central regions of our Galaxy. For that, we obtained precise age distributions for the non-negligible amount of super-metal-rich stars ([M/H] ∼ 0.5) in the solar neighbourhood (more than 5% of the total stars within 400 pc of the plane). Assuming that these stars were born in the inner Galaxy and migrated outwards, those distributions should be indicative of the true stellar age distribution in the inner Galaxy. Surprisingly, we find that these age distributions are not continuous but show clear signs of episodic star formation (∼13.5, 10.0, 7.0, 4.0, 2.0, and less than 1 Gyr ago). Interestingly, with the exception of the 4 Gyr event, the timings of the detected events coincide with the formation of the primitive Milky Way and with known merging events or satellite encounters (Gaia-Enceladus-Sausage, Sagittarius dwarf galaxy, and the Magellanic Clouds), suggesting that these events could have triggered global star-forming episodes. These results are compatible with a scenario in which Gaia-Enceladus-Sausage is responsible for the formation of the bar 10 Gyr ago. However, we cannot associate any accretion counterpart with the event that occurred 4 Gyr ago, leaving open the possibility of a late formation of the bar, as previously proposed. The Auriga Superstars simulations also indicate that metal-rich stars in the solar neighbourhood-like regions formed at discrete times and migrated from the inner parts of barred galaxies, suggesting a possible link to bar dynamics and satellite accretion. This novel analysis allows us to indirectly witness the evolution of the inner Milky Way and constrain dynamical models of the Milky Way bar
Ecotourism and environmental conservation in the small island of Gaspar, Marinduque, Philippines: A baseline for responsible tourism
No full textThis study assesses the ecotourism potential, environmental challenges, and management gaps of Gaspar Island using focus group discussions (FGDs) with local stakeholders and the Tourism Rapid Assessment (TRA) manual. Gaspar Island, part of the Tres Reyes Islands in Barangay Pinggan, Gasan, Marinduque, served as the focal site. The TRA revealed a diverse economic base including fishing, agriculture, seaweed farming, and handicrafts, alongside natural and cultural assets such as coral reefs, caves, and the Kwebungo burial site. These resources offer potential for marine tours, agri-tourism, and cultural workshops. However, the FGDs identified issues, including seasonal tourism dependency, inadequate infrastructure, and unregulated visitor flows. Environmental threats such as waste mismanagement, reef degradation, and overfishing are exacerbated by weak enforcement and fragmented planning. Community engagement is hindered by elite dominance and minimal participation. Current management practices are perceived as reactive and underfunded, prompting calls for stronger policy implementation, environmental stewardship, and inclusive governance. The integration of TRA data and stakeholder input underscores the need to balance development with conservation. Key recommendations include the establishment of marine protected areas, improved waste management systems, and community-led initiatives. Achieving sustainable ecotourism on Gaspar Island will require reforms that promote environmental resilience, cultural preservation, and participatory management
Ex-post damage impact assessment of the marcopper mining disaster in Marinduque, Philippines
No full textThe 1996 Marcopper Mine Disaster remains the most significant event in the Philippines. There is various impact assessments had been conducted about the disaster but none of them consider full public participation, consideration of biodiversity, and analysis of cumulative effects. This research aims to quantify economic and environmental losses from the disaster using multi-dimensional impact assessment framework involving integration of economic valuation methods and primary stakeholder consultations. This would be assessing the impact of the disaster human health, livelihood, and sediment deposition. Heavy metal exposure drives public health concerns such as toxicity, skin lesions, and disease costing the government to allocate Php 3.3 million for toxicology programs and treatment of affected individuals. The disaster tainted community livelihood with a 99% decline in fishery and aquaculture production exacerbated by contamination perceptions that also reduces other livelihood activities — producing total foregone income of Php 50,131,795. Presence of heavy metals in the mine tailings are being deposited in Boac and Mogpog River, and Calancan Bay which continue to distress water ecosystems, initiate flooding, and acidif pore waters. Interventions used to mitigate the disaster impacts found to be short-term solutions, encouraging the government to revisit strategies and policies related to Marcopper Disaster
Co-production of resilient green infrastructure in urban river management through community participation and partnerships in Payakumbuh City, Indonesia
No full textRiver infrastructure is vital in maintaining ecological and social resilience, particularly in urban areas vulnerable to environmental degradation and flooding. This study focuses on the Batang Agam River in Payakumbuh City, analyzing collaborative arrangements among local government, city administration, and communities in river management. A qualitative approach was employed with purposive sampling techniques. Data were collected through observation, documentation review, and in-depth interviews with local government officials, river care communities, and local business actors. Analysis was conducted using the Manual Data Analysis Procedure (MDAP). The findings reveal the critical role of the River Care Community Forum as a mediator, activity facilitator, and supervisor of cleanliness, order, and security across river segments. Government support was evident through participation in cleanup campaigns, facility provision, and program oversight, involving subdistrict offices, the Environmental Agency, and the Civil Service Police Unit. Beyond its ecological function, the river area has become a space for community economic empowerment through small-scale enterprises such as culinary businesses, parking services, and other micro-businesses, all managed environmentally sustainably. Overall, this collaboration revitalized the river ecosystem and contributed to achieving the Sustainable Development Goals, particularly Goal 17 on partnerships, while serving as a model for community participation-based sustainable solutions
Evaluating the effectiveness of PCA-based indicator reduction on ANN performance for hotel maintenance classification in Yogyakarta
No full textThe hospitality industry in Yogyakarta faces challenges in maintaining hotel facilities efficiently, prompting the need for data-driven maintenance classification systems. This study evaluates the effectiveness of reducing eleven hotel maintenance indicators using Principal Component Analysis (PCA) and analyzing its impact on Artificial Neural Network (ANN) performance. PCA reduced the indicators to nine principal components while retaining 93% of the data variance, and these components were used to train a multilayer perceptron ANN model. The PCA-based model achieved 90.57% accuracy and a macro-F1 score of 0.9106, slightly lower than the original model using all indicators, which attained 94.34% accuracy with fewer misclassifications. This research provides the first empirical assessment of PCA-based dimensionality reduction in the hotel maintenance context, revealing that although PCA enhances computational efficiency, it can remove subtle yet important information crucial for precise classification. The results highlight that PCA alone may be insufficient for high-precision maintenance prediction and should be complemented with alternative or hybrid feature-selection methods. For hotel managers, the findings emphasize the importance of complete and informative input variables in AI-based maintenance systems, which may be further strengthened through real-time IoT data integration
Consideration of cultural ecosystem service indicators in determining spatial zoning in urban spatial plans
No full textCultural Ecosystem Services (CES) refer to the intangible advantages that individuals derive from ecosystems, which play a crucial role in enhancing both human well-being and the sustainability of urban areas. Although these services are vital, they are frequently difficult to measure and incorporate into conventional zoning practices within urban planning. This research explores a framework designed to systematically embed CES indicators—such as access to recreational opportunities, scores for aesthetic value, and density of cultural heritage—into the urban zoning decision-making process. Through a case study method, we present a technique for mapping and assessing the supply and demand of important CES categories, converting this information into spatial constraints and opportunities relevant to zoning regulations. The findings reveal that the integration of CES indicators leads to more multifunctional and equitable spatial plans, particularly concerning the distribution of green infrastructure and protected cultural areas. This research provides practical guidance for urban planners to move beyond traditional land-use criteria and embrace a holistic, ecosystem-based approach to spatial zoning
Effect of fly ash on shear strength of a volcanic soil as embankment material based on direct shear test
No full textFly ash is a non-hazardous by-product of high-temperature coal combustion and is commonly found in large quantities in coal mining areas. This condition creates an opportunity to reuse fly ash as an alternative material, particularly when blended with volcanic soil for embankment construction on mining haul roads. In haul road design, the shear strength of embankment materials is an essential geotechnical parameter. This study evaluates the influence of fly ash on the shear strength of a fly ash (FA) + volcanic soil (Soil-C) mixture. Shear strength parameters were obtained through laboratory direct shear testing in accordance with ASTM D3080. The fly ash was sourced from a stockpile in the Tanjung Selor coal mining area, North Kalimantan, while the volcanic soil originated from Lagadar, West Java. Two mixture proportions were tested: 35% FA + 65% Soil-C and 50% FA + 50% Soil-C. The results indicate that increasing the fly ash content from 35% to 50% enhances the internal friction angle by approximately 10°, while reducing cohesion by about 6 kPa. These findings demonstrate that higher fly ash content can improve frictional resistance but decreases the cohesive bonding within the FA-volcanic soil embankment material
Evaluation of The Building Evacuation Facility System Based on Health Meter Regulation No. 43 of 2019 and Government Regulation No. 16 of 2021
No full textGetting health services is one of the rights owned by the people of Indonesia. In its implementation, the government also provides facilities in the form of community health centers to support the Indonesian people in getting the right to health services. The procurement of the community health center itself, of course, also pays attention to the aspects that have been determined. One of these aspects is the evacuation facility system, which prioritizes security and safety for its users. By optimizing the evacuation facility system in the community health center building, it will certainly be able to support comfort for all users without exception. Through this research, it is hoped that awareness will be raised to build the buildings that can not only function according to their roles, but also can be a safe place for all users
Characteristic of short-range exposure to cough-produced vortex rings under different mouth shapes and velocities using large eddy simulation
No full textCoughing is one of the major routes for the transmission of respiratory diseases in indoor environments. Previous studies have shown that coughing can form vortex ring structures. However, the conditions under which cough-generated vortex rings form, as well as the influence of boundary condition on the formation and flow characteristics of these vortex rings, remain inadequately understood. This study investigates the effects of three velocity profiles (real-cough, sinusoidal, and pulsation) and five outlet shapes (real-mouth, circular, square, rectangular, and elliptical) on the flow dynamics of cough jets. The results show that the penetration distance of cough-generated vortex rings ranges from 0.56 to 0.68m in 0.5s. Separated (or deviated) vortex rings show a power-law distribution in the cough jets:
s~ t2/3 (or s ~ t1/2) during the initial stage and s ~ t1/3 (or s ~ t1/5) during the interrupted stage. Due to the differences between the power-law and existing studies, short-distance infection risk assessment models require further revision. Furthermore, the real-mouth, circular, and square have a relatively minor effect on the formation of saturated vortex ring compared to velocity profiles. The formation conditions for saturated vortex rings can be determined by a dimensionless energy αlim= 0.2±0.06