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Cover: Cirrus uncinus cloud [1]
[1] Gobato, M. R.R. (2025). Cirrus uncinus cloud. MS040, Anhanduí, MS, 12 (UTC), Coordinates: -21.015148, -54.001036. Nov 10, 2025.
Cover: Electronic circuit [2]
[2] Lütfi Ulusoy, Meltem Apaydın Üstün and Reşat Mutlu. (2025). “Design of an Adjustable Warburg Inductor Using an Op-Amp-Based Gyrator and Fractional-Order Capacitor Implementation”, Parana Journal of Science and Education. 11(6)40-48. https://sites.google.com/site/pjsciencea/v-11-n-1-6-2025/v-11-n-6-december
Cirrus uncinus is a species of cirrus cloud. The name cirrus uncinus is Latin for "curly hooks". Commonly called "mare's tail", this cloud species is very thin and generally sparse in the sky. The clouds occur at high altitudes, at a temperature of about −50 to −40 °C (−58 to −40 °F). They are generally seen when a warm or occluded front is approaching. They are very high in the troposphere and generally mean that precipitation, usually rain, is approaching. Abbreviation Ci unc; Genus Cirrus ("curl"); Species uncinus ("hook"); Altitude above 7,000 m(23,000 ft); ClassificationFamily A (High-level); Appearance curly, hooked; Precipitation: No, but may indicate precipitation approach. [3]
[3] Creative Commons 4.0. Cirrus uncinus cloud. URL: https://en.wikipedia.org/wiki/Cirrus_uncinus_cloud
Energy Conservation in General Relativity
Stefan Bernhard Rüster and Antonino Del Popolo
Parana J. Sci. Educ., v.11, n.6, (1-10), December 1, 2025.
Abstract
This article shows that the vanishing covariant divergence of the energy-momentum tensor of the matter is a conservation law. Furthermore, it is explained why energy-momentum pseudotensors of the gravitational field cannot represent its energy density, but this is described up to a factor by the Einstein tensor. The necessarily existing conservation law of total energy, momentum, and stress in general relativity is derived, thereby explaining the phenomena of dark energy and dark matter and solving the cosmological constant problem and the cuspy halo problem. In Newton’s theory of gravity, it is the modified Poisson equation that fulfills the requirement of conservation of total energy. Using a model that solves the modified Poisson equation, it turns out that dark matter in modified Newtonian cosmology is nothing other than a central point-like mass, probably a supermassive primordial black hole, thus refuting the cosmological principle and explaining both the Hubble and S_8 tensions. A simple but fairly accurate model is presented that solves the modified Poisson equation to fit the calculated rotation curves to the observed speeds in spiral galaxies, which consist of several components: the central black hole, the bulge, the disk, and the dark matter.
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Impacts of Climate Change on Food Production in the Context of Population Growth: A Case Study of East Timor
Nelson Moniz da Costa
Parana J. Sci. Educ., v.11, n.6, (11-16), December 1, 2025.
Abstract
Climate change is recognized as a global challenge; however, for developing countries such as Timor-Leste, its impacts are particularly severe relative to their limited economic capacity to adapt. The continuous growth of the population, coupled with a decline in food production, further exacerbates the country’s vulnerability. Therefore, this study aims to examine the impact of climate change on food production in the context of a steadily increasing population, using a comprehensive review of existing literature. Ultimately, the study seeks to develop a model that illustrates the interrelationships between climate change, the decline in food production, emigration trends, rising food insecurity, and increasing dependence on imports.
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Investigation of the Water Detection Performance of the Water-In-Fuel (WIF) Sensor in Diesel Fuel
Erdal Kılıç, Ertuğrul Karakulak, Ersoy Mevsim and Reşat Mutlu
Parana J. Sci. Educ., v.11, n.6, (17-22), December 1, 2025.
Abstract
In diesel engine systems, water in the fuel is one of the main pollutants that adversely affect the performance of the engine and the life of its components. In this study, the sensing performance of Water-in-Fuel (WIF) sensors for diesel fuel engines was investigated in solutions of water with different ratios of ethylene glycol and water mixtures and at varying water hardness levels. As the water hardness increased, the sensor output voltage decreased; at hardnesses above 3°F, no water warning was obtained from the sensor. WIF sensors lose sensitivity at high glycol ratios (70% and above) due to low conductivity, and at mixtures above 80%, the water warning from the sensor is either very short or does not occur at all. This indicates that the sensor can only detect soft water. The results showed that the efficiency of the sensor varies depending on the conductivity of the water and the mixing properties.
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Revolutionizing Environmental HRM through Artificial Intelligence: Toward a Smarter, Sustainable Workforce
Noor Mohammad, Nahida Nargis and Prabal Barua
Parana J. Sci. Educ., v.11, n.6, (23-34), December 1, 2025.
Abstract
The present paper marks a literature review and offers an integrative critique of the role of Artificial Intelligence (AI) in Environmental or Green Human Resource Management (HRM), inspired by 40 full coverage of scholarly journals, serving to provide cogent answers against the backdrop of Technology as a sustainable technology dilemma related to effective management of the workforce. Based on an examination of existing AI uses, ethical issues, corporate preparedness, and behaviour mediators, the review develops a conceptual model of how AI can facilitate more innovative workforce analytics, tailored green engagement, intelligent automation, and the ethical governance of the enterprise, thereby attentively motivating the creation of sustainable organizational cultures. Concrete implications in reaching the responsible adoption of AI in accordance with the current sustainability goals of companies and views on the future of technologies, and the professional adherence to corporate social responsibility emphasize the fact that there are critical gaps in empirical validation, ethical issues, the development of technologies, and their adaptation to the industry. It represents the transformative role of AI as an impetus toward achieving a sustainable competitive advantage, as this review highlights that consistent interdisciplinary studies and creative practice are necessary to fully realize the potential of AI-enhanced Environmental HRM and promote international sustainability goals.
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Economic costs of antiretroviral treatment (ART) in Costa Rica as a low-middle-income country: trends, challenges, and sustainability prospects
Erick Calvo and Claudia Nelly Orozco González
Parana J. Sci. Educ., v.11, n.6, (35-39), December 1, 2025.
Abstract
Over the past decade, the cost of antiretroviral therapy (ART) has become an increasingly complex challenge for health systems in low- and middle-income countries (LMICs). This article offers a comprehensive review of the literature and key documents to explore both the direct and indirect costs associated with ART. It places particular emphasis on comparing generic versus brand-name medications, the impact of international aid programs—such as the U.S. President’s Emergency Plan for AIDS Relief (PEPFAR) and the Global Fund— and the role of public policies in shaping access and equity in healthcare. To conduct this analysis, we conducted a narrative review of studies published between 2010 and 2023, drawing from indexed databases like PubMed, Scielo, and LILACS, as well as reports from leading global health organizations including the WHO, PAHO, and UNAIDS. The findings reveal a gradual reduction in drug costs, largely driven by the introduction of generics. However, significant barriers remain, particularly in terms of out-of-pocket expenses and unequal access to coverage. In Costa Rica, pilot initiatives involving pre-exposure prophylaxis (PrEP) have provided valuable insights into the financial sustainability of HIV prevention efforts within the framework of the Costa Rican Social Security Fund (CCSS), the country’s sole public healthcare provider. This review contributes meaningful evidence to inform public health decision-making, highlighting the importance of sustainable financing for comprehensive HIV prevention strategies and long-term ART access in resource-constrained settings.
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Design of an Adjustable Warburg Inductor Using an Op-Amp-Based Gyrator and Fractional-Order Capacitor Implementation
Lütfi Ulusoy, Meltem Apaydın Üstün and Reşat Mutlu
Parana J. Sci. Educ., v.11, n.6, (40-48), December 1, 2025.
Abstract
Warburg capacitors can be implemented using RC ladder networks, allowing the realization of elements with impedance behavior of the form Z_{c}(s)=1/C_ {α} s^{0.5} . These elements are widely used in modeling diffusion processes in electrochemical systems. On the other hand, gyrator circuits—particularly those based on operational amplifiers—are commonly used to simulate inductors using active components and capacitors. In this study, we propose a method for constructing an adjustable Warburg inductor whose impedance is Z_{L}(s)=L_{β} s^{0.5} by integrating a Warburg capacitor into an opamp-based gyrator circuit. The resulting system exhibits a fractional-order inductive behavior with tunable parameters, providing a versatile tool for simulating diffusion-controlled inductive elements in analog circuits. Potential applications include bioimpedance modeling, electrochemical systems, and the design of fractional-order filters. Moreover, the circuit can be effectively used as an educational tool in analog electronics or electrochemistry laboratories to demonstrate the behavior of fractional-order elements and active inductor simulations.
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